Multi-layer laminated molding

Technical field

The present invention relates to a multi-layer laminated molded article having a laminate structure of at least three types and three layers, in which a specific adhesive layer is sandwiched therebetween, and in particular a useful multi-layer laminated molded article in the form of a container, a packaging bag, different parts and the like, wherein the presence or absence of the adhesive layer in undamaged condition can be demonstrated using the ultrasonic reflection method, which has excellent barrier shadows and which has properties which are excellent for quality control or process control.

State of the art

As is well known to date, multi-layer laminated molded articles obtained by laminating non-polyolefinic resins such as a polyamide resin (PA), a polyester resin, a saponified product of an ethylene-vinyl acetate copolymer (ethylene-vinyl alcohol copolymer), a halogen-containing resin, e.g. B. a polyvinyl chloride resin (PVC) and polyvinylidene chloride resin (PVDC), a polycarbonate resin (PC) and a polymer mixture of a polyphenylene oxide resin and a polyamide, a foil of a metal such as aluminum, iron, copper, tin and nickel, an alloy, the metal as the main component (e.g. stainless steel), a synthetic resin film with vacuum-deposited aluminum oxide, silicon oxide, functions of gas and vapor barrier properties, an improvement in appearance such as surface gloss and coating properties, and are widely used as various molded parts such as packaging containers, packaging bags and industrial parts.

Many of these multi-layer laminated molded articles use a structure of a high-pressure process polyethylene resin (low-density polyethylene resin), a polyethylene resin produced at moderate or low pressure, as the main material layer from the viewpoints of economy, moldability and machinability, weldability, moisture resistance and water resistance. Linear Low Density to High Density Polyethylene Resin), a polypropylene resin, of an olefin copolymer resin and a composition containing these as main components and, if necessary, various fillers such as calcium carbonate, talc, mica, glass fibers, carbon fibers and organic fibers.

Since these polyolefin resins have a non-polar molecular structure, their adhesive properties, affinity, and compatibility with the aforementioned polyolefin resins and metallic materials are poor, and the imparting of the aforementioned properties by polar monomer modification (graft polymerization) of the polyolefin resin is used a copolymer of an olefin (especially ethylene) and a polar monomer, Compounding (blending) a polar resin or treatment with chemical or physical agents is widely used. Particularly in the case where the molding is carried out by a co-extrusion process, it is well known that with a so-called modified polyolefin resin modified with a polar monomer as an adhesive material, a multilayer laminate is prepared with the aforementioned various materials (e.g. B. Japanese Patent Publication Nos. 12782/1986 and 39448/1980 and "'87 -2 (packaging material report) market trend and development history for coextrusion multilayer films and foils (Sogo Hoso Shuppan Co., Ltd., published on February 27, 1987, pages 285 to 293).

When such multilayer laminates are made, it is believed that disposable containers that have a relatively short useful life and that are not subjected to severe impact during the manufacture of the products or merchandise and during the transportation step have no need for the benefit of an interlayer adhesive. For molded parts such as containers, bags and parts that require a long shelf life and high resistance to vibrations and various types of impact, not only is the adhesive property and durability of the adhesive layer of great importance, it is even more important and It is necessary to determine whether the adhesive layer that contains the molded body is present or absent in the desired position.

If there is a place in the multi-layer laminated molded part, in particular in a container and a bag, where the adhesive layer is missing completely or partially from an unexplained cause, there is a risk that the mechanical properties may be impaired. When evaluating the durability over a long period of time, if the contents are liquid or gaseous, there is a possibility that these contents remain in the unconnected areas and exert influences on the entire multi-layer laminated molded part, which reduce its performance and also reduce its appearance and ultimately its product value. In addition, there is the possibility that water and moisture from the atmosphere remain at the unconnected points and thereby exert the same influences as above.

If such possibilities exist, it is necessary to determine whether the adhesive layer is present in the multi-layer laminated molded body over the entire desired area. A method which allows the presence of an adhesive layer to be detected easily and economically without destroying the multi-layer laminated molded part was not known. Although as a method to detect the presence of the adhesive layer of the multi-layer laminated molded article in advance, a method in which a part of the laminated molded article is cut out and the sectional area of ​​the cut article by various techniques (e.g., examination with a magnifying glass, an optical one Microscope) in general use, a sample used for this detection cannot be used as a molded part. According to this method, it can only be assumed that the adhesive layer could be present in the multi-layer laminated molded part; however, this method is not a sufficiently safe method.

On the other hand, the presence of the adhesive layer can be confirmed in multi-layer laminated moldings with relatively high transparency by using optical analytical techniques, etc. However, this method is limited to relatively thin and is affected by the molecular structure of the non-polyolefin resin. The process is therefore unreliable.

In addition, a method can be considered in which the adhesive layer is colored by using an adhesive mixed with a dye such as a pigment, and the presence of the adhesive is confirmed by viewing or by using a color difference meter, etc. However, this method has serious limitations on product appearance, and when the outer layer is opagne and the layer thickness is large, the method is not applicable.

Consequently, in general, the aforementioned methods of prior detection and a technique in which the presence of the adhesive is checked by examining the amount of the adhesive previously used and that after the molding of the product and comparing the amount of the adhesive used with that the thickness, surface area and density of the adhesive layer in the laminated molded article are calculated or estimated. In addition, a method has been proposed in which a detection medium such as iron powder or glass fiber is inserted into a specific layer in multi-layer extrusion molding and detected using a magnetic sensor or an ultrasonic head (Japanese Patent Application Laid-Open No. 260417/1988). However, this introduction is impractical in terms of reducing the adhesive properties, durability, flexibility and impact resistance

In recent years, it has been proposed to use a laminated molded article as a fuel tank, such as an automobile tank, which has long-term durability and high resistance to vibration and various types of shock.

Metallic tanks have been used to date, but the trend is toward synthetic resin tanks from the standpoint of tank weight reduction, freedom of shape, volume increase, and anti-corrosion properties (e.g., Tsuzuki et al, "Plastics" Vol. 23, No. 8, page 52 (1972), ibid., Vol. 23, No. 5, page 113 (1972), ibid., Vol. 23, No. 11, page 131 (1972), "Nikkei New Materials "published on 29. February 1988, pages 34-35, and Hara et al., "Plastics" Vol. 39, No. 6, page 109 (1988)). In addition, in order to improve the gas-liquid shut-off property of the fuel, a fuel tank has been proposed which comprises a plurality of layers in which the number of layers in the tank is increased, and as a material for each layer, a low-pressure polyethylene resin, a modified one Polyethylene resin and a polyamide resin are used (e.g. Kurihara et al., SAE Technical Document Series No. 870304 (February 23-27, 1987), Fukuhara "Plastics Age", Vol. 35, No. 3, page 129 (1989)). In connection with the structure, there are the three types-three-layer structure, in which a low-pressure polyethylene resin is used as the outer layer, a modified polyethylene layer is used as the intermediate layer, and a polyamide resin is used as the inner layer, and a three-type five-layer structure in which a low pressure polyethylene resin is used as inner and outer layers, a polyamide resin is used as an intermediate layer and an adhesive layer is interposed between each of the inner and outer layers and the intermediate layer; this is considered a promising fuel tank with penetration resistance to fuel.

Similar are e.g. B. multilayer molded articles which have at least one modified polyolefin resin layer with adhesive properties for a polyamide resin / a polyamide resin layer or a modified polyolefin resin layer / a polyamide resin layer / a modified polyolefin resin layer. A polyamide resin such as polyamide 6 (nylon 6) has excellent permeation resistance against fuel, especially gasoline.

On the other hand, with recent developments, so-called alcohol gasoline blends obtained by mixing alcohol such as methyl alcohol or ethyl alcohol with gasoline are already used mainly in areas in South America, and this tendency is gradually spreading to other areas with North America as the center , Studies of materials showing good barrier properties when used on such alcohol gasoline blends confirmed that a saponified product of an ethylene-vinyl acetate copolymer (hereinafter referred to as "EVOH") is excellent.

In addition, in addition to the fact that known polyethylene adhesives are critically inadequate in terms of their adhesion properties to EVOH or PA and in terms of their long-term adhesive durability, it is extremely important, as described hereinafter, that the presence in containers having such a multilayer structure an adhesive layer between the main material layer and the barrier materials such as EVOH or PA is confirmed positive.

The reason for this is that a fuel tank installed in a car is classified as an important safety component and has to meet extremely strict and high performance standards. As a result, this case corresponds to the multi-layer fuel tank equipped with fuel permeation resistance. For a modified polyethylene resin as an adhesive and the barrier layer to be used in such tanks, more stringent performance levels are required as a tank. In view of the adhesive resin used therein, it is necessary that the adhesive properties to the polyethylene resin and EVOH or PA and the long-term durability under various conditions are excellent, excellent mechanical properties, thermal properties and chemical properties are present, and the moldability and processability are good are. In addition, since these properties depend very much on the fact that the adhesive layer is safely present in the molded part, it is more important to create a method with which the presence or absence of the adhesive layer can be verified.

In summary, it can be seen that if there is a location in a multilayer liquid fuel tank where the adhesive layer is not completely or partially absent due to unexplained causes, not only the mechanical properties such as the impact resistance deteriorate but also, in connection with the long-term durability, the fuel remains in the vacant position, which considerably deteriorates various properties of the tank, which causes serious problems. For this reason, the detection of the presence of the adhesive layer in consumer goods such as the aforementioned multi-layer fuel tanks becomes an inevitable important checkpoint. However, an established technique by which the presence of the adhesive layer can be detected without destroying a product having such a multi-layer structure has not been described in any way. Although the detection of the presence of the EVOH layer in the above multi-layer structure can be achieved without destroying the container using the ultrasonic reflection method, it is difficult to confirm the presence of the adhesive layer in the multi-layer laminated molded body having the structure EVOH or PA layer / adhesive layer / Main material layer to detect without destroying the molded body, and no attempts have been made.

Although the invention described in the aforementioned Japanese Patent Application Laid-Open No. 260417/1988 is quite effective, more concrete examples and dates of the various materials are not available, and also. in the present invention, it is believed that there is a problem in the detection of the follow-up properties when the injection speed of the multi-layer blank is high. Furthermore, since it is important, as described above, that the presence of the layer in the container is finally confirmed, it is believed that this invention is insufficient in these points.

In addition, multi-layer laminated molded parts such as containers and bags for use in industrial chemicals or edible oils and water-containing foods, in particular juices, fruits, vegetables, meat, fish, etc., require particularly strong release properties, water resistance and durability in order to prevent deterioration in the quality of the contents and it is important that the adhesive can be detected without destroying the molding.

As described above, molded parts such as containers and bags, which require long-term durability, shut-off or separation properties and high resistance to vibrations, have hitherto been used as multi-layer laminated molded parts, e.g. B. fuel tank and edible oil tank, no satisfactory suggested.

The present inventors therefore made various studies on a method of detection using ultrasonic waves and a combination of a main material layer mainly composed of a polyolefin resin and an adhesive layer to overcome the above-mentioned problems in the prior art, and discovered as a result that non-destructive detection of the adhesive layer using an ultrasound reflection method, that was previously unknown can be achieved using a specific adhesive and adjusting the difference in acoustic impedance between the main material layer and the adhesive layer to a specific value or more.

On the basis of these findings, the present invention has been completed, and the object of the present invention is to provide a multi-layer laminated molded article which has excellent properties such as release properties, allows the detection of the adhesive layer without destruction and is free of spots for whom the adhesive layer is absent or partially absent.

Disclosure of the present invention

That is, the present invention provides a multi-layer laminated molded article having a layer structure having a main material layer containing a polyethylene resin as a main component on the outside and a layer of a saponified product of an ethylene-vinyl acetate copolymer (EVOH) or a layer of a polyamide resin (PA) on the outside, which are laminated with at least one adhesive layer, which is arranged in the form of a sandwich between them, wherein:

the adhesive layer comprises a resin composition containing:

(A) 60 to 95% by weight of a polyethylene resin selected from the group consisting of:

(1) a low pressure polyethylene resin having a density of at least 0.930 g / cm³, a number of short chain branches per 1000 carbon atoms of the main chain of not more than 20 and a flowability of at least 0.01 g / 10 min,

(2) a low density polyethylene resin having a linear structure with a density of 0.910 g / cm³ to less than 0.935 g / cm³ and a flowability of 0.1 to 50 g / 10 min, a melting point determined by a differential scanning calorimeter (im hereinafter abbreviated as "DSC") from 115 to 130 ° C and a number of short-chain branches per 1000 carbon atoms of the main chain from 5 to 30,

(3) a modified low pressure polyethylene resin obtained by grafting an unsaturated carboxylic acid and / or its derivative on the above low pressure polyethylene resin (1); and

(4) a modified low-density polyethylene resin with a linear structure obtained by grafting an unsaturated carboxylic acid and / or its derivative onto the above low-density polyethylene resin with a linear structure (2);

said polyethylene resin contains at least 0.1% by weight of the modified low pressure polyethylene resin (3) and / or the modified low density polyethylene resin with linear structure (4), and

(B) 40 to 5% by weight of an extremely low density polyethylene resin having a linear structure with a density of 0.890 g / cm³ to less than 0.910 g / cm³, a number of short-chain branches per 1000 carbon atoms of the main chain from 18 to 60, a fluidity of 0.1 to 30 g / 10 min and a melting point determined by DSC of 110 to 125 ° C, and

said resin composition has a density of at least 0.925 g / cm³ and a proportion of the grafted unsaturated carboxylic acid and / or its derivative from 0.001 to 5.0% by weight, and

a difference in acoustic impedance between the main material layer and the adhesive layer, determined using ultrasonic waves of 20 to 25 MHz, of at least 8.5 x 10 -3 g / cm 2 µsec.

Brief description of the figure

Fig. 1 shows a model of a pulse waveform obtained when an ultrasonic wave is incident on a three-type-five-layer multi-layer laminated molding from the main material layer side, and the pulse reflected from each of the interfaces of the three occurring layers with an oscilloscope Observation of the waveform is displayed.

The symbols indicate the following:

A: Peak of the surface of the main material layer (incident side);

B: peak of the interface between the main material layer and the adhesive layer;

C: peak of the interface between the adhesive layer and the EVOH or PA layer; and

D: Peak of the interface between the EVOH or PA layer and the adhesive layer (the side opposite to the incident side).

Best mode for carrying out the invention

The multilayer laminated molded article of the present invention will now be described in detail. As described above, the multi-layer laminated molded article of the present invention has the layer structure in which a main material layer containing a polyethylene resin as a main component is laminated on the outside and an EVOH layer or PA layer on the inside by at least one specific adhesive layer.

(1) Main material layer

As the polyethylene resin to be used as the main component of the main material layer in the present invention, ethylene homopolymers and a copolymer of ethylene and another α-olefin can be listed. The α-olefins are generally olefins having 3 to 12 carbon atoms (preferably 3 to 8 carbon atoms). Typical examples of the α-ole-fine are propylene, butene-1, hexene-1, octene-1 and 4-methyl-pentene-1.

In the main material layer, only the aforementioned polyethylene resin or a small amount (up to a maximum of 20% by weight) of an elastomer or other synthetic resin which is evenly compatible with the polyethylene resin can be mixed. As usable elastomers can be polyisobutylene, ethylene-propylene copolymer rubber (EPR), ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR) and block or random styrene-butadiene copolymer -Rubbers (SBR) can be listed. As other synthetic resins, copolymers of ethylene and vinyl acetate, methyl ester, ethyl ester and butyl ester of acrylic acid or methacrylic acid can be listed. In addition, various polymers such as PA, a polyester resin, EVOH and PVC can be mixed in a range that does not seriously deteriorate the basic properties of the polyethylene resin as the main component.

Fillers which are generally added to the aforementioned polyolefin resins can be added to the main material layer. The amount added is preferably set to not more than 30% by weight. Calcium carbonate, talc, mica, glass fibers, carbon fibers, metal fibers, other inorganic fibers and organic polymer fibers (e.g. polyester fibers, polyamide fibers) can be listed as fillers. In the present invention, when the elastomer, the other synthetic resin and the filler are blended into the aforementioned polyethylene resin, the amount of these blended components is such that their total amount is not more than 40% by weight. When the total amount is more than 40% by weight, there arises a problem that the formability and workability, impact resistance, fuel resistance, etc. are reduced.

Although the flowability (measured according to JIS-K 7210 under Condition 4 of Table 1; hereinafter referred to as "MFR") of the polyethylene resin as the main component of the main material layer in the multi-layer laminated molding of the present invention is not critical, it is from the viewpoint of Mouldability and processability in general at least 0.005 g / 10 min, preferably at least 0.01 g / 10 min and particularly preferably at least 0.02 g / 10 min.

Among the polyethylene resins, preference is given to ethylene polymers which are selected from an ethylene homopolymer and a copolymer of ethylene and an α-olefin with a density of at least 0.930 g / cm³, particularly preferably at least 0.935 g / cm³. In addition, an ethylenic polymer composition having a density of at least 0.930 g / cm³ can be used, particularly preferably at least 0.935 g / cm³, which by admixing with these ethylene homopolymers and copolymers of ethylene and α-olefins, of low-pressure polyethylene with a density of less than 0.930 g / cm³ and a copolymer of ethylene and a monomer other than an α-olefin, and a propylene homopolymer and a copolymer of propylene and ethylene or other α-olefins.

Among these ethylenic polymers, medium or high density polyethylenes with a density of at least 0.935 g / cm³ are particularly suitable.

(2) barrier material layer

In the present invention, EVOH or PA is used as the barrier material. EVOH and PA have excellent shut-off properties against fuels such as petrol. EVOH in particular has strong barrier properties against alcohol and water.

(a) Layer of a saponified product of an ethylene-vinyl acetate copolymer (EVOH)

EVOH that can be used can be made e.g. B. by saponification of an ethylene-vinyl acetate copolymer (EVA) with alkali and the like. The proportion of copolymerization of ethylene in the EVA is usually 20 to 80 mol% and particularly preferably 25 to 75 mol%. If the copolymerization ratio of the ethylene is less than 20 mol%, the moldability and processability are poor. On the other hand, the multi-layer laminated molding obtained is unsatisfactory in terms of the barrier properties against the permeation of gas or liquids if it is more than 80 mol%. Although the degree of saponification is not critical, it is usually at least 90%, particularly preferably at least 95% from the point of view of the barrier property. Similarly, when the degree of saponification is less than 90%, the barrier property of the obtained multi-layer laminated molded article is not sufficiently high.

Although the molecular weight of the EVOH is not critical, the melt flow index (MFI) measured according to JIS-K 7210, Condition 4 (190 ° C, 2160 g load) is 0.5 to 20 g / 10 min and preferably 1 to 10 g / 10 min , One type of EVOH can be used, or two or more types of EVOH can be used in combination. In addition, a polyamide resin or a thermoplastic polyvinyl alcohol which is compatible with EVOH can be used in a mixture with EVOH as long as it does not seriously deteriorate the barrier property or melt moldability. In particular, mixing a thermoplastic polyvinyl alcohol with EVOH allows higher gas and liquid barrier properties to be obtained.

(b) polyamide resin layer (PA layer)

As the polyamide resin that can be used, there can be listed nylon 6, a copolymer of nylon 6, modified nylon 6, nylon 11, nylon 12 and nylon 6-6. Among them, preferred are those which have a melting point of not more than 265 ° C when dry, among which those with a melting point of not more than 235 ° C are particularly suitable. These polyamide resins can be used alone or as mixtures of two or more of them. In addition, those obtained by bonding with a metal foil (e.g. aluminum, iron, copper) or an alloy (e.g. stainless steel) with at least one surface of the polyamide resins, and various synthetic films can be used. onto which the above metal or alloy or silicon dioxide is deposited in a vacuum, so-called metal vacuum deposited films are used.

(3) adhesive layer

In the multi-layer laminated molded article of the present invention, the adhesive layer comprises a resin composition which comprises: (A) 60 to 95% by weight of a polyethylene resin selected from the group consisting of (1) a low pressure polyethylene having a density of at least 0.930 g / cm³, a number of short chain branches per 1000 carbon atoms of the main chain of not more than 20 and an MFR of at least 0.01 g / 10 min, (2) a low density polyethylene resin having a linear structure and a density of 0.910 g / cm³ to less than 0.935 g / cm³, an MFR of 0.1 to 50 g / 10 min, a melting point, determined by DSC, from 115 to 130 ° C and a number of short-chain branches per 1000 carbon atoms of the main chain from 5 to 30, (3) a modified low-pressure polyethylene resin obtained by grafting an unsaturated carboxylic acid and / or its derivative onto the above low-pressure polyethylene resin (1) and (4) a modified low density polyethylene resin with a linear structure, obtained by grafting an unsaturated carboxylic acid and / or its derivative onto the low-density polyethylene resin with a linear structure (2), said polyethylene resin comprising at least 0.1% by weight of the modified low-pressure polyethylene resin (3) and / or the modified low-density polyethylene resin with a linear structure (4), and (B) 40 to 5% by weight of an extremely low density, linear structure polyethylene resin having a density of 0.890 g / cm³ to less than 0.910 g / cm³, a number of short chain branches per 1000 carbon atoms in the Backbone from 18 to 60, an MFR from 011 to 30 g / 10 min and a melting point, determined by DSC, from 110 to 125 ° C, said resin composition having a density of at least 0.925 g / cm³ and a proportion of the grafted unsaturated carboxylic acid and / or its derivative from 0.01 to 5.0 wt .-%.

"Modified" hereinafter refers to those to which the unsaturated carboxylic acid and / or its derivative has been grafted, and "unmodified" to those that have not been grafted.

The low-pressure polyethylene resin as low-pressure polyethylene resin (1) and the modified low-pressure polyethylene resin (3) as component (A), which form part of the adhesive layer, is a polyethylene resin with a density of at least 0.930 g / cm³, a number of short-chain branches per 1000 carbon atoms of the main chain of at most 20 and an MFR of at least 0.01 g / 10 min.

The low pressure polyethylene resin is obtained by homopolymerizing or copolymerizing ethylene alone or ethylene and an o-olefin having 3 to 12 carbon atoms (preferably 3 to 8 carbon atoms) in the presence of a so-called Phillips catalyst or Ziegler catalyst and is generally under a pressure of atmospheres -pressure up to 100 kg / cm² (1 kg / cm² = 0.981 bar) (medium to low pressure polymerisation). Preferred examples of the α-olefins are propylene, butene-1, hexene-1,4-methylpentene-1 and octene-1. Their copolymerization ratio is not more than 6.5% by weight and preferably not more than 6.0% by weight. Low pressure polyethylene resins can be used alone or in combination of two or more thereof.

The density of the low pressure polyethylene resin is at least 0.930 g / cm³, preferably at least 0.933 g / cm³ and particularly preferably at least 0.935 g / cm³. The use of low pressure polyethylene is excellent in that the rigidity, heat resistance, fuel resistance, surface hardness, etc. of the product are increased.

In addition, the MER is at least 0.01 g / 10 min, preferably at least 0.015 g / 10 min and particularly preferably at least 0.02 g / 10 min. If the MFR is less than 0.01 g / 10 min, the moldability and processability are poor. Although the upper limit is not critical, it is usually 50 g / 10 min and particularly preferably not more than 35 g / 10 min.

Especially when the MFR is less than 0.01 g / 10 min, the MFR of the obtained low-pressure grafted polyethylene resin will generally be reduced very much below the MFR of the low-pressure polyethylene resin used for the graft modification, which, although depending on the graft modification conditions, not only leads to a reduction in formability and processability, but also leads to a serious decrease in compatibility when preparing a mixture with an unmodified low-pressure polyethylene resin, so that a uniform composition cannot be obtained. The MFR of the modified polyethylene resin is therefore generally at least 0.05 g / 10 min. In particular, it is at least 0.1 g / 10 min.

The linear structure (2) low density polyethylene resin used, like the above low-pressure polyethylene resin, is one that is industrially manufactured and used in many fields because it is particularly excellent in its environmental stress cracking, transparency, heat sealability, resistance to brittleness and its properties at low temperatures (e.g. packaging materials such as foils and industrial materials such as pipes). This linear structure low density polyethylene resin is produced by copolymerizing ethylene and the aforementioned α-olefins using a so-called Ziegler catalyst by the gas phase method, the solution method and the slurry method.

The density of the low density polyethylene resin and linear structure (2) is from 0.910 g / cm³ to less than 0.935 g / cm³, preferably from 0.912 g / cm³ to less than 0.935 g / cm³ and particularly preferably from 0.913 g / cm³ to less than 0.935 g / cm³. The MFR is from 0.1 to 50 g / 10 min, preferably from 0.2 to 40 g / 10 min and particularly preferably from 0.2 to 30 g / 10 min. If the MFR of the low-density polyethylene resin having a linear structure is less than 0.1 g / 10 min, processability and moldability are poor. On the other hand, the composition obtained has low mechanical strength if it is more than 50 g / 10 min.

The melting point of the linear structure low density polyethylene resin determined by DSC is 115 to 130 ° C, preferably 118 to 130 ° C, and particularly preferably 118 to 125 ° C. If the melting point determined by the DSC method is less than 115 ° C, the long-term solvent resistance at high temperatures is poor. On the other hand, the density exceeds the upper limit of the range described above when it is more than 130 ° C.

The number of short-chain branches per 1000 carbon atoms of the main chain of the linear low-density polyethylene resin is from 5 to 30, and particularly preferably from 5 to 25. If the number of short-chain branches per 1000 carbon atoms of the main chain is below or below the lower limit in any case, the uniformity of the composition of the present invention becomes low, which is not desirable. That is, when using a composition using low-density linear structure polyethylene resin having a number of branches per 1000 carbon atoms of the main chain outside the above-mentioned range, it is in the evaluation of long-term solvent resistance (e.g. Fuel resistance), in particular the reduction in elongation at break is large, and in addition, under the conditions requiring heat resistance (more specifically, the durability test in an atmosphere of at least 100 ° C), there is an additional deterioration in physical properties; both of which are considered to result from the non-uniformity of the composition.

The modified polyethylene resins used as component (A) of the present invention (ie, the modified low-pressure polyethylene resin (3) and the modified low-density and linear structure (4) polyethylene resin (4)) are obtained by grafting the unsaturated carboxylic acid and / or its derivative such as described below, on the low pressure polyethylene resin and / or the low density polyethylene resin with a linear structure as described above. This grafting reaction is carried out in the presence of a radical initiator. In this case, synthetic resins and elastomers (rubber), as described in the following, which have an affinity for the low-pressure polyethylene resin to be grafted or for the low-density polyethylene resin with a linear structure , may be present. The reaction can be carried out by known methods, e.g. B. the methods described in Japanese Patent Application Laid-Open Nos. 10107/1987 and 132345/1986.

As the unsaturated carboxylic acid and its derivatives for use in the grafting treatment of the present invention, monovalent unsaturated carboxylic acids and dibasic unsaturated carboxylic acids and their metal salts, amides, imides, esters and anhydrides can be listed. Among them, monovalent unsaturated carboxylic acids and their derivatives having 20 or less carbon atoms are generally preferred, among which those with 15 or less carbon atoms are more preferred. In addition, as the dihydric unsaturated carboxylic acids and their derivatives, those with 30 or less carbon atoms are usually preferred, among which those with 25 or less carbon atoms are more preferred. Typical examples of these unsaturated carboxylic acids and their derivatives are described in Japanese Patent Application Laid-Open No. 10107/1987. Among these unsaturated carboxylic acids and their derivatives, acrylic acid, methacrylic acid, maleic acid and their anhydrides, 5-norbornene-2,3-dicarboxylic acid and their anhydride and glycidyl methacrylate are preferred, with maleic anhydride and 5-norbornene anhydride being particularly preferred.

The amount of the unsaturated carboxylic acid and its derivative used in the graft modification is generally 0.01 to 5.0 parts by weight, preferably 0.01 to 3.0 parts by weight and particularly preferably 0.02 to 2.0 parts by weight per 100 Parts by weight of the polyethylene resin to be grafted. If the proportion of the unsaturated carboxylic acid and its derivative is less than 0.01 part by weight, in total, the graft modification is insufficiently carried out, and there arise problems in affinity or adhesive properties which are intended by the present invention. On the other hand, if it is more than 5.0 parts by weight, there is a risk that the obtained graft-modified low-pressure polyethylene resin and the graft-modified low-density polyethylene resin having a linear structure are subject to gelation, discoloration and deterioration; the improvement in properties intended by the present invention is not observed.

As the radical initiator, those having a decomposition temperature for the one-minute half-life of 100 ° C or more are generally used, among which those at 103 ° C or more are preferred and those at 105 ° C or more are particularly preferred. Suitable radical initiators include organic peroxides such as dicumyl peroxide; benzoyl peroxide; Di-tert-butyl peroxide; 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane; 2,5-dimethyl-2,5-di (tert-butylperoxy) hexin-3; lauroyl peroxide; and tert-butyl peroxybenzoate. The proportion of the radical initiator is usually 0.001 to 1.0 part by weight, preferably 0.005 to 1 part by weight, and particularly preferably 0.005 to 0.5 part by weight, per 100 parts by weight of the polyethylene resin to be grafted. If the proportion of the radical initiator is less than 0.001 part by weight, the effect of the graft modification is insufficient, which means that not only is a long time required for the complete graft modification, but also unreacted materials are present in the mixture , On the other hand, if it is more than 1.0 part by weight, undesirable excessive decomposition or crosslinking reactions occur.

Olefinic resins which may coexist at the time of the above graft reaction include high-pressure low-density polyethylene resin and copolymers of ethylene and other vinyl monomers, such as ethylene-vinyl acetate copolymers, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid - Copolymer, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer and an ethylene-methyl methacrylate copolymer. Synthetic and natural rubbers such as ethylene-α-olefin copolymer rubbers (e.g. ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymer rubber and ethylene-butene-1 copolymer) can be listed as the elastomer Rubber, polyisobutylene rubber, polyurethane rubber, styrene-butadiene copolymer rubber and polybutadiene rubber. These are generally used in an amount of not more than 10% by weight in the polyethylene resin to be grafted, with an amount of not more than 5% by weight being particularly preferred. If the proportion as the total amount of the olefin resin and / or the elastomer in the total amount of the low-pressure polyethylene resin and / or the low-density polyethylene resin having a linear structure is more than 10% by weight, the basic properties of the low-pressure polyethylene and / or the low-density polyethylene resin become sometimes deteriorated with linear structure.

The modified polyethylene resins used as component (A) in the present invention (ie, the modified low-pressure polyethylene resin (3) and the modified low-density polyethylene resin having a linear structure (4)) are obtained by grafting an unsaturated carboxylic acid and / or its derivative as in described below on a low pressure polyethylene and / or a low density polyethylene resin with a linear structure as described above. This grafting reaction is carried out in the presence of a radical initiator. At this time, there may be a resin and an elastomer (rubber) as described below with an affinity for the low-pressure polyethylene resin to be grafted and the low-density polyethylene resin having a linear structure. This method can, for. B. the methods described in Japanese Patent Application Laid-Open Nos. 10107/1987 and 132345/1986.

As a reaction, there can be mentioned a method in which the low-pressure polyethylene resin to be processed is kneaded in the molten state using an extruder, a Banbury mixer, a kneader, a solution method in which the polymers such as the low-pressure polyethylene resin and the polyethylene resin are co-processed low density and linear structure are dissolved in a suitable solvent, a slurry process in which polymer particles, how the low-pressure polyethylene resin is processed in the suspension state, or a gas phase grafting process.

The reaction temperature is appropriately selected taking into account the deterioration of the polymers such as the low-pressure polyethylene resin and the low-density polyethylene resin having a linear structure, the decomposition temperature of the unsaturated carboxylic acid and its derivative and the decomposition temperature of the radical initiator to be used. Taking the above kneading method in a molten state as an example, the reaction temperature is usually 100 to 350 ° C, and preferably 150 to 300 ° C. 180 to 300 ° C is particularly preferred.

In this way, of course, the modified low-pressure polyethylene resin and the modified low-density polyethylene resin having a linear structure of the present invention are manufactured. In order to improve the efficiency, known processing methods such as the method described in Japanese Patent Application Laid-Open No. 10107/1987, e.g. B. a method in which treatment with an epoxy compound or a polyfunctional compound containing, for example, an amino group or a hydroxyl group at the time of graft modification or after graft modification, and further a method in which unreacted monomers (unsaturated carboxylic acid and its derivative) and various by-product components are removed by heating, washing, etc.

In the multi-layer laminated molded article of the present invention, it is necessary that the adhesive layer contain the extremely low density, linear structure polyethylene resin as component (B). A method of manufacturing this extremely low density, linear structure polyethylene resin is well known, and in recent years, e.g. B. industrially manufactured by an improved slurry polymerization process or the gas phase polymerization process and widely used.

It is therefore, unlike conventional known ethylene-α-olefin random copolymers (density 0.86 to 0.91 g / cm³) with low crystallinity with a degree of crystallization from several percent to about 30%, which is obtained by the polymerization using a Vanadium catalyst system can be obtained, a polyethylene resin with extremely low density and linear structure, which is produced according to the slurry method or the gas phase method using a stereoregular catalyst (so-called Ziegler catalyst), as described for. B. is described in Japanese Patent Application Laid-Open Nos. 68306/1982, 23011/1984 and 109805/1986.

The extremely low density, linear structure polyethylene resin of component (B) is an extremely low density, linear structure polyethylene resin having a density of 0.890 g / cm³ to less than 0.910 g / cm³, an MFR of 0.1 to 30 g / 10 minutes, a melting point determined by DSC, from 110 to 125 ° C and a number of short chain branches per 1000 carbon atoms of the main chain from 18 to 60.

In the present invention, when the density of the above resin is less than 0.890 g / cm³, problems in the fuel resistance of the obtained composition arise. On the other hand, if it is more than 0.910 g / cm³, the impact resistance of the composition obtained is insufficient. For this reason, the density is preferably between 0.890 to 0.910 g / cm³. If the MFR of the above resin is less than 0.1 g / 10 min, moldability and processability are not desirable, and if it is more than 30 g / 10 min, an impact problem arises. For these reasons, the MFR is preferably 0.1 to 10 g / 10 min, with 0.2 to 8.0 g / 10 min being particularly preferred.

In addition, the melting point, measured by DSC (approximately 5 mg of a sample is weighed out, placed in the DSC measuring apparatus, the temperature increased from room temperature to 200 ° C at a rate of temperature rise of 10 ° C / min, held at this temperature for 5 minutes, is brought to room temperature with a temperature decrease rate of 10 ° C / min, and further increase in temperature with the above temperature rise rate; the temperature of the peak of the maximum heat absorption area is called the "melting point") is between 110 to 125 ° C. Those at 112 to 125 ° C are particularly preferred. If the melting point is less than 110 ° C, the composition obtained is insufficient in heat resistance, and if it is more than 125 ° C, the effect of improving the impact resistance is poor.

The number of short-chain branches per 1000 carbon atoms of the main chain of the above resin is 18 to 60, preferably 18 to 50 and particularly preferably 20 to 50. If the number of short-chain branches per 1000 carbon atoms of the main chain is less than 18, the multilayered laminate is used Molding has problems with impact resistance, and if it is more than 60, fuel resistance will deteriorate considerably. The short chain as used here essentially refers to an alkyl group having 1 to 10, preferably 1 to 6, carbon atoms.

In addition, from the viewpoint of the effect of improving the impact resistance, the initial tensile modulus of the above polyethylene resin is not more than 2 x 10³ kgf / cm², and preferably not more than 1.5 x 10³ kgf / cm². Such polyethylene resins are obtained by copolymerizing ethylene and the aforementioned α-olefin using a Ziegler catalyst.

It is required for the resin composition constituting the adhesive layer of the present invention that the above component (A) has at least 0.1% by weight of the modified high-density polyethylene resin (low-pressure polyethylene resin) and / or the modified low-density polyethylene resin and contains linear structure. If the content of the entire modified polyethylene resin is less than 0.1% by weight, the adhesive intended by the present invention, which has the affinity or adhesion properties to the aforementioned resin materials and metal materials, etc., cannot be obtained. The content of the modified polyethylene resin is preferably at least 1.0% by weight and particularly preferably at least 2.5% by weight.

The resin composition forming the adhesive layer of the present invention comprises the aforementioned components (A) and (B), and their mixing ratio is as follows: the proportion of component (A) is 60 to 95% by weight and the proportion of component (B) is 40 to 5% by weight, preferably the proportion of component (A) is 62 to 95% by weight and The proportion of component (B) is 38 to 5% by weight, and particularly preferably the proportion of component (A) is 62 to 93% by weight and the proportion of component (B) is 38 to 7% by weight. If the proportion of the extremely low density polyethylene resin having a linear structure in the composition is less than 5.0% by weight, the obtained laminate structure material is deteriorated in impact resistance, and if it is more than 40% by weight fuel resistance (especially fuel resistance at 40 ° C) is significantly reduced, which is not desirable.

The resin composition constituting the adhesive layer in the present invention, like the aforementioned components (A) and (B), may contain an unmodified low-pressure polyethylene resin and / or an unmodified low-density polyethylene resin having a linear structure. That is, in general, it is difficult to graft the polymer (in the present invention, the low-pressure polyethylene resin or the low-density polyethylene resin having a linear structure) with a monomer (in the present invention, the unsaturated carboxylic acid and its derivative) to graft all of the polymers; Parts of the polymers remain ungrafted. In the present invention, the low-pressure polyethylene resins or the low-density, linear-structure polyethylene resins that are not grafted can be used as such without insulation. In addition, non-modified low-pressure polyethylene resins and / or low-density polyethylene resins having a linear structure that have not been subjected to the grafting treatment can be mixed.

In the present invention, when unmodified low pressure polyethylene resin (1) is added, the amount thereof is preferably not more than 99.9% by weight of the component (A), with not more than 99.0% by weight particularly are preferred. If the proportion of the unmodified low-pressure polyethylene resin (1) is more than 99.9% by weight, the adhesive properties are insufficient.

When unmodified low density polyethylene resin having a linear structure (2) is added, the amount thereof is preferably 2.5 to 75% by weight of the component (A), with 5.0 to 60% by weight being particularly preferred. If the proportion of the unmodified linear polyethylene resin (2) is less than 2.5% by weight, the uniformity of the composition in the overall composition deteriorates. On the other hand, if it is more than 75% by weight, the heat resistance and the long-term fuel resistance at high temperatures are deteriorated. In the resin composition constituting the adhesive layer of the present invention, some of the entire components of the composition may be mixed in advance and the remaining components may be mixed, or the entire components of the composition may be mixed together at the same time. In any event, the proportion of the grafted monomer (saturated carboxylic acid and / or its derivative) in the adhesive of the present invention is 0.001 to 5.0% by weight, preferably 0.01 to 2.0% by weight, and the total amount thereof particularly preferably 0.02 to 1.0% by weight. When the proportion of the grafted monomer occupying the adhesive as a total amount thereof is less than 0.001% by weight, various effects of the invention cannot be sufficiently achieved. On the other hand, if it is more than 5.0% by weight, no further improvements in the effects of the present invention can be obtained.

The composition of the resin composition constituting the adhesive layer in the present invention requires that the various conditions mentioned above be met and at the same time selected so that the density of the adhesive is at least 0.925 g / cm³ and the difference in the acoustic impedance between the main material layer and the adhesive layer, determined using ultrasonic waves from 20 to 25 MHz, is at least 8.5 x 10-3 g / cm² µsec. The density of the adhesive must be at least 0.925 g / cm, with at least 0.926 g / cm³ being particularly preferred. If the density of the adhesive is less than 0.925 g / cm³, the long-term solvent resistance is not good.

The acoustic impedance of the adhesive layer (hereinafter referred to as "Z 1") is at least 1,980 x 10 &¹ g / cm² µsec, preferably at least 1,982 x 10¹¹ g / cm² µsec, and particularly preferably at least 1,984 x 10¹¹ g / cm² .mu.sec. If Z & sub1; is less than 1.980 x 10-2 g / cm² µsec, the fuel resistance, heat resistance, etc. are not sufficiently high.

On the other hand, although the acoustic impedance (Zo) of the main material layer is not critical, it is determined using ultrasound waves from 20 to 25 MHz, preferably at least about 2.00 x 10 &¹ g / cm² µsec, preferably at least 2, 10 x 10 &¹ g / cm² µsec and particularly preferably at least 2.20 x 10 &¹ g / cm² µsec.

However, in order to be able to detect the presence or absence of the adhesive layer by a non-destructive method, the acoustic impedance difference is Z 0 - Z 1. between the main material and the adhesive layer at least 8.5 x 10-3 g / cm² µsec, preferably at least 9.0 x 10-3 g / cm² µsec and particularly preferably at least 9.5 xg / cm² µsec. That is, when Z & sub0; Is 2.2 x 10 &¹ g / cm² µsec, Z & sub1; not more than 2.115 x 10 &¹ g / cm² µsec and when Z & Is 2.00 x 10 g / cm² µsec, Z & sub1; not more than 1.915 x 10 &¹ g / cm² µsec. If the difference in acoustic impedance between the main material layer and the adhesive layer is less than 8.5 x 10 -3 g / cm 2 µsec, it will be very difficult to obtain ultrasonic detection for the presence or absence of the adhesive layer in the non-destructive state.

In the preparation of any composition of the present invention, additives such as antioxidants, thermal stabilizers, ultraviolet absorbers, lubricants, antistatic agents and pigments (dyes) commonly used in the field of polyolefin resins can be admixed to an extent that does not have the effects of the composition significantly impaired.

As the mixing method for the preparation of the composition, any of the various mixing methods usually used in the field of synthetic resins can be used, ie a method in which dry mixing is carried out using a mixer such as a free-fall mixer or a Henschel mixer, and a method in which melt kneading is carried out using a kneader such as an extruder, a kneader, a Banbury mixer and a roller. A more uniform composition can be obtained by performing two or more of these mixing processes (e.g. a method in which the dry mixing is carried out in advance and the mixture thus obtained is further kneaded in the melt).

According to the present invention, the multilayer laminated molded article of the present invention can be produced by laminating the main material and the EVOH or the PA through the aforementioned adhesive layer (3) by a method commonly used in the field of synthetic resins, and further, molding into one desired shape. The lamination can be done by a process in which the main material, the adhesive and EVOH or PA are used by using three or more extruders (e.g. multi-layer, blow, coextrusion inflation and T-die film forming) are co-extruded, a method using EVOH or PA as the substrate and the main material and the adhesive thereon are co-extruded and coated (coating or laminating), and the method of hot contact bonding. In addition, a method is available in which the materials are separately formed as films or foils and then subjected to the thermal contact connection.

In the context of the layer structure of the laminate for the multi-layer laminated molding of the present invention, assuming that the main material layer is A, the adhesive layer is B and the EVOH or PA layer is C, the structures are A / B / C, A / B / C / B, A / B / C / B / A or structures in which these structures are repeated and further assuming that the other barrier material layer is D, layer D can be arranged between layer B and layer C, and further, if necessary, layer B can be arranged between layer C and layer D in the form of a sandwich.

In the present invention, depending on the desired physical properties of the target molded article and taking into account the properties of the resins, it suffices to determine which of the EVOH layer and the PA layer is used as the barrier material layer C. If necessary, EVOH and PA layers can be used in combination.

In order to effectively use overflowing molding compositions which are formed at the time of product molding, they are usually finely pulverized, and melt-kneaded if necessary to make the composition uniform, using an extruder, etc. and recycled for use in the main material layer, or it can be a layered structure with a fresh recycled layer E provided on the outside of layer A and between layer A and layer B, such as A / E / B / C or I / O / B / C can be used.

In the present invention, when a container particularly for fuels or cooking oils, etc. is typically a process in which the blow molding is performed using a multi-layer blow molding machine equipped with extruders designed to coextrude the main material, EVOH or PA and the adhesive in such a way that the adhesive, sandwiched between the main material and EVOH or PA, and further with a multi-layer nozzle (in a concentric circular shape). The above blow molding process is detailed in Japanese Patent Application Laid-Open No. 104707/1987, "Polymer Digest" March, 1988 (Vol. 40, No. 3, pages 33 to 42) and "Plastics Age" March, 1989, pages 129 to 136 described.

In the context of the structure in which the molding is a fuel tank, the structures, assuming that the main material layer is A, the adhesive layer is B, the EVOH or PA layer is C, A / B / C, A / B / C / B and A / B / C / B / A or structures that repeat these structures and assuming that the further barrier layer is D, layer D can be between layer B and layer C. can be arranged, and further, if necessary, another layer B may be placed between layer C and layer D, or layer D may be provided on the outside of A and B, as in D / B / A / B / C and A / B / C / B / D. Combinations of these (e.g. D / B / A / D / B / C) can of course be used.

In the molded part of the present invention, the thicknesses of the main material layer, the adhesive layer and the EVOH or PA layer are appropriately determined depending on the behavior required for the desired molded part, the behavior of the molding machine, and the use, shape, type the composition used, etc. In particular in containers for fuels or edible oils, etc. The thicknesses of the adhesive layer and the EVOH or PA layer are each several micrometers to 3 mm, preferably 10 μm to 2 mm and particularly preferably 10 μm to 1 mm. The thickness of the main material layer is 0.3 to 10 mm, with 0.5 to 7 mm being particularly preferred.

It is possible that overflowing plastic masses obtained from the manufacture of the container are ground using a grinder and then finely divided by the use of an extruder, e.g. B. so that the size of the EVOH or PA is not more than about 100 microns, and then they are used in about 5 to 50% admixture with the main material. In this case, however, it must be ensured in advance that, compared with the case where no section is used, the obtained fuel tank is not deteriorated in performance and long-term stability, that is, there are no problems in its practical use.

Whenever the melt kneading for the production of the above-mentioned adhesive is carried out in the present invention, and when the lamination is carried out for the production of the multi-layer laminated molded article, it is necessary to work at temperatures at which the various polyethylene resins, synthetic resins, Melt elastomers, EVOH and PA. However, when working at high temperatures, they are sometimes subject to heat decomposition. For the above reasons, it is generally operated at 170 to 280 ° C and preferably at 190 to 250 ° C.

The present invention will be described in more detail with reference to the examples and comparative examples.

Examples 1 to 12 and Comparative Examples 1 to 9

(1) Production of Modified Polyethylene

Various modified polyethylene resins used as adhesive components in the examples and comparative examples were produced as follows. The polyethylene resin is abbreviated as "PE".

Modified PE (a)

To powdered low-pressure PE (hereinafter referred to as "HDPE") with a density of 0.952 g / cm³ and an MFR of 0.93 g / 10 min, 0.012 part by weight of 2,5-dimethyl-2, 5-tert-butyl-peroxyhexane was given as a radical initiator, which was then dry blended using a Henschel mixer for two minutes, and then 0.375 part by weight of maleic anhydride (hereinafter referred to as "MAH") was added, and the mixture was dry blended for two minutes using the Henschel mixer, melt kneaded at a resin temperature of 257 ° C, and pelletized. The amount of the grafted MAH in the modified PE (a) thus obtained was 0.33% by weight, determined by the infrared spectral method.

Modified PE (b)

To powdered HDPE (2) having a density of 0.945 g / cm³ and an MFR of 0.44 g / 10 min, 0.012 part by weight of 2,5-dimethyl-2,5-tert-butylperoxyhexane was added as a radical initiator, which was then carried out for two minutes were dry blended using a Henschel mixer, and then 0.375 parts by weight of MAH was added, and the mixture was dry blended for an additional 2 minutes using a Henschel mixer, kneaded and pelletized in the melt at a resin temperature of 260 ° C. The amount of the grafted MAH in the modified PE (b) thus obtained was 0.32% by weight as determined by the infrared spectral method.

Modified PE (c)

To low density PE and linear structure (hereinafter referred to as "LLDPE") (LLDPE (3)) with a density of 0.925 g / cm³, an MFR of 0.78 g / 10 min, a melting point of 120.5 ° C and to a number of branches of 9.5 / 1000 C, 0.012 part by weight of 2,5-dimethyl-2,5-tert-butylperoxyhexane was given as a radical initiator, which was then dry mixed for two minutes using a Henschel mixer, after which 0.375 part by weight of MAH was added . and the mixture was dry blended for an additional two minutes using a Henschel mixer, melt kneaded at a resin temperature of 255 ° C and pelletized. The amount of the grafted MAH in the modified PE (c) thus obtained was 0.30% by weight, determined by the infrared spectral method.

Modified PE (d)

To LLDPE (4) with a density of 0.900 g / cm³, an MFR of 4.0 g / 10 min, a melting point of 98 ° C and a number of branches of 72/1000 C, 0.012 part by weight of 2.5- Dimethyl-2,5-tert-butylperoxyhexane was added as a radical initiator, which was then dry mixed for two minutes using a Henschel mixer, and then 0.375 part by weight of MAH was added. and the mixture was dry blended for an additional two minutes using a Henschel mixer, melt kneaded at a resin temperature of 232 ° C and pelletized. The amount of the grafted MAH in the PE (d) thus obtained was 0.26% by weight determined by the infrared spectral method.

The properties of the unmodified extremely low density, linear structure PE (hereinafter referred to as "L-ULDPE"), which was also used, were as follows:

L-ULDPE (5)

Density 0.904 g / cm³, MFR = 1.0 g / 10 min, melting point 120 ° C and number of branches 28/1000 C made by the slurry polymerization process.

L-ULDPE (6)

Density 0.897 g / cm³, MFR 0.7 g / 10 min, melting point = 115 ° C and number of branches 47/1000 C, produced by the slurry polymerization process.

L-ULDPE (7)

Density 0.907 g / cm³, MFR = 6.5 g / 10 min, melting point = 121 ° C and number of branches 21/1000 C made by the slurry polymerization process.

L-ULDPE (8)

Density 0.900 g / cm³, MFR = 4.0 g / 10 min, melting point = 98 ° C and number of branches 72/1000 C, produced by the solution polymerization process.

(2) Manufacture of the adhesive

The aforementioned modified polyethylene resin (modified PE), the unmodified polyethylene resin (unmodified PE) and the unmodified extremely low density and linear structure polyethylene resin (L-ULDPE) were mixed in the proportions shown in Tables 1 and 2 and then at kneading at a temperature of 200 to 220 ° C using a single-screw extruder with a diameter of 50 mm, to produce the adhesives (1) to (16) shown in Tables 1 and 2.

The density () of the adhesive obtained was measured according to the JIS-K7112 method, and an acoustic thickness meter manufactured by Nippon Panametrics Co., Ltd. was measured in terms of acoustic impedance (Z). used, which was equipped with a vertical depth sensor with a piezo element as an oscillation plate, the speed of sound (c) when an ultrasonic wave with a frequency of 20 MHz on a press plate (30 mm x 30 mm) of 2 mm thickness in the thickness direction hit, was measured and the acoustic impedance was calculated by the following equation:

Z = xc (g / cm² µsec) Table 1 Table 2

(3) Production of a multilayer laminate

As shown in Tables 3 and 4, using the above-mentioned adhesives (1) to (16) as the adhesive and as the main material, HDPE (A) having a high-load melt index (measured according to JIS-K7210 under condition 7 of Table 1; hereinafter abbreviated as "HLMFR") = 4.8 g / 10 min, density = 0.945 g / cm³ and an acoustic impedance (Z 0) = 2.23 x 10 g / cm² µsec, or HDPE (B) with an MFR = 0.3 g / 10 min, a density = 0.948 g / cm³ and Z & sub0; = 2.26 x 10 &¹ g / cm² µsec and additionally as EVOH, EVOH with an ethylene content of 29 mol%, a melting point determined by the DSC method, of 189 ° C, an MFR = 4 g / 10 min at 230 ° C and a density of 1.20 g / cm³, the molding of three types - five layers - multilayer laminates (molding temperature 210 ° C, thickness increase: each main material layer 1.5 mm, each adhesive layer 0.10 mm, EVOH layer 0.08 mm ) carried out.

From the flat portion of the above laminate, a multi-layer piece with a width of 10 mm and a length of 150 mm was obtained, which was then regarding its initial adhesive strength P 0. was measured between the adhesive layer and the EVOH layer according to the T-type peeling method using a tensile tester under the conditions of a peeling speed of 50 mm / min, with the results shown in Tables 3 and 4.

The same multilayered piece was left in an oven at 115 ° C for 96 hours and then immersed in a mixed solution consisting of 90% by volume of a commercially available common gasoline and 10% by volume of methanol at 40 ° C for 1000 hours, and after that, after setting the conditions in an atmosphere of 23 ° C and 50% RH for more than 50 hours, the adhesive strength P & sub1; measured under the same conditions. By comparison with P & sub0; For the evaluation of the long-term heat resistance and the fuel resistance, the degree of preservation of the adhesive strength (value of P 1, with P 0 set to 100) was determined, and the evaluation is shown in Tables 3 and 4.

In addition, the determination of the detectability of the adhesive was carried out by the following method. That is, the above-mentioned device used in the acoustic impedance measurement was used, an ultrasonic wave (frequency 20Mhz) was irradiated on each multilayer laminate film, and the pulse waves reflected from the respective interfaces became was output to an oscilloscope for observing the waveform equipped with a polaroid camera for recording, and the pulse waves were recorded using the camera. A model of the record is shown in FIG. 1. Fig. 1 shows a pulse waveform of pulses reflected from the respective interfaces, output to an oscilloscope for observation when an ultrasonic wave is irradiated on a three-type, five-layer, multi-layer laminate film from the main material layer side has been. Explained in more detail, the ordinate axis denotes the intensity of the reflected wave and the abscissa axis means the distance in the direction of the thickness of the multilayer laminate film.

The pulse input from the left side of Fig. 1 shows an intensity peak of the reflected wave denoted by (A). on the surface of the main material layer and then part of the pulse enters the laminate forming the material wall, goes through the thickness of the main material layer, corresponding to the distance between peak A and peak B, and is then on the surface of the adhesive layer (interface between the adhesive layer and the main material layer), denoted by the peak B, is reflected.

In Fig. 1, peaks A and B are in opposite directions, which means that the acoustic impedance (Z 1) of the adhesive layer is lower than (Z 0) of the main material layer (Z 0> Z 1); are natural when Z & sub1; > Z 0, the peaks in the same direction.

Then, further parts of the pulse, after passing through the thickness of the adhesive layer (distance between peak B and peak C), are reflected at the interface between the adhesive layer and the EVOH layer, which is denoted by the peak C. After passing through the EVOH layer (distance between peak C and peak D), it is reflected as indicated by peak D.

When this measurement method is used, assuming that the difference between the intensity peaks of the reflected wave of the main material layer and the intensity peak of the reflected wave of the adhesive layer h & sub1; and the difference between the peak of the main material layer and the peak of the EVOH layer h & sub2; when h & sub1; / h & sub2; is less than 0.08, it is judged to be "undetectable" and when h 1 / h 2 Is 0.095 or more than "detectable". The reason for this is that when h 1 / h 2; is less than 0.095, it becomes difficult to distinguish the peak of the interface between the main material layer and the adhesive layer due to the disturbance of the waveform due to noise.

The symbols behind the figure of h 1 / h 2 shown in Tables 3 and 4 indicate the detectability evaluated by the following criteria:

: Very well detectable

O: Well verifiable

Δ: Verifiable

X: Can only be detected with difficulty Table 3

* means separating the layer comprising the main material layer and the adhesive layer. Table 4

** means that the spread is large.

Examples 13 to 21 and Comparative Examples 10 to 16

(1) Production of Modified Polyethylene

Various modified polyethylene resins used as adhesive components in the examples and comparative examples were produced as follows.

Modified PE (e)

To 100 parts by weight of a powder of HDPE (8) with a density of 0.951 g / cm³ and an MFR of 0.85 g / 10 min, 0.01 part by weight of 2,5-dimethyl-2,5-tert-butylperoxy-hexane was added which were then dry blended for 2 minutes using a Henschel mixer. Then 0.35 part by weight of MAH was added and the mixture was dry blended for an additional two minutes. Pellets were produced while melt-kneading the mixture obtained above at a resin temperature of 255 ° C using an extruder. The amount of the grafted MAH in the modified PE (e) thus obtained was 0.32% by weight.

Modified PE (f)

Modified PE (f) was prepared by performing dry mixing and melt kneading in the same manner as the modified PE (e), except that instead of HDPE (8), which was used in the production of the modified PE (e) HDPE (9) with a density of 0.944 g / cm³ and an MFR of 0.40 g / 10 min was used. The amount of MAH grafted in the modified PE (f) was 0.31% by weight.

Modified PE (g)

Dry blending and melt kneading were carried out in the same manner as for the modified PE (e), except that instead of the HDPE (8) LLDPE (10) used in the production of the modified PE (e) with a density of 0.924 g / cm³ and an MFR of 0.8 g / 10 min was used (melting point 120 ° C, number of ethyl group branches per 1000 carbon atoms of the main chain 10). The amount of the grafted MAH in the modified PE (g) obtained was 0.29% by weight.

Modified PE (h)

Dry mixing and melt kneading were carried out in the same manner as in the modified PE (e), except that instead of the HDPE (8) L-ULDPE (11) used in the production of the modified PE (e) with an MFR of 1.8 g / 10 min (melting point 98 ° C, number of branches 75), and melt kneading was carried out at 230 ° C. The amount of the grafted MAH in the obtained PE (h) was 0.26 g / cm³.

The properties of the unmodified L-ULDPEs that were used similarly are as follows:

L-ULDPE (12)

Unmodified ultra low density polyethylene resin with linear structure having a density of 0.905 g / cm³, an MFR of 1.02 g / 10 min, a melting point of 120 ° C and a number of branches of 30 made by the slurry polymerization process.

L-ULDPE (13)

Unmodified ultra-low density polyethylene resin having a linear structure with a density of 0.899 g / cm³, an MFR of 0.93 g / 10 min, a melting point of 114 ° C and a number of branches of 44 made by the slurry polymerization process.

L-ULDPE (14)

Unmodified ultra-low density polyethylene resin with a linear structure having a density of 0.907 g / cm³, an MFR of 9.0 g / 10 min, a melting point of 121 ° C and a number of branches of 23 made by the slurry polymerization process.

(2) Manufacture of the adhesive

Modified polyethylene resin (modified PE), unmodified polyethylene resin (unmodified PE), and unmodified ultra-low density, linear structure (L-ULDPE) polyethylene resin, the types and blending amounts of which are shown in Table 5, were in advance for 5 minutes mixed using a Henschel mixer. Each of the obtained mixtures was melt-kneaded while pellets (the composition) were produced at a resin temperature of 215 ° C using an extruder (diameter 50 mm). The compositions (adhesives) (17) to (23) thus obtained were measured for their density and acoustic impedance in the same manner as in Example 1. The results are shown in Tables 5 and 6.

(3) Manufacture of a multi-layer fuel tank

As shown in Tables 5 and 6, the aforementioned adhesives (17) to (23) were used as adhesives, a low pressure polyethylene resin (hereinafter referred to as "HDPE (C)) with an HLMFR of 5.0 g / 10 min. A density of 0.945 g / cm³ and an acoustic impedance of 2.23 x 10 &¹ g / cm² µsec was used as the main material and EVOH with an ethylene content of 29 mol%, MFR (210 ° C, 2.16 kg) of 3.1 g / 10 min and a melting point of 191 ° C. A three-type, five-layer, multi-layer fuel tank with an internal volume of 45 L (L = liter) and a total weight of 5.8 kg was made at 220 ° C using a multi-layer blow molding machine with a 3-type, 5-layer nozzle in concentric circular shape, with which the molding machine was equipped, in order to manufacture using the extruders with the respective diameters 90 mm, 40 mm and 30 mm, in such a way, that the average thicknesses of the various layers were such that the inner and outer layers of the main material were 3.0 mm thick, the inner and outer layers of the adhesive were 0.15 mm thick and the EVOH layer was 0.10 mm thick. With regard to the adhesive strength before the treatment of the container obtained, a piece with a width of 10 mm and a length of 150 mm was cut out of the flat portion of the rectangular container and its adhesive strength between the adhesive and the EVOH layer in accordance with the T- Type peeling method examined using a tensile tester at a peeling speed of 50 mm / min. In addition, test pieces were also cut out, and each test piece was left in an oven at 110 ° C for 72 hours and then immersed in a mixed solution consisting of 85% by volume of commercially available common gasoline and 15% by volume of methyl alcohol for 1500 hours at 40 ° C. Then, each test piece was taken out and held for 150 hours under the conditions of the temperature of 23 ° C and the relative humidity of 50%, and then the adhesive strength after the treatment was measured.

In this way, the initial adhesive strength and the degree of maintaining the adhesive strength were measured, and the difference in acoustic impedance and detectability were measured in the same manner as in Example 1 with the results shown in Tables 7 and 8.

Example 22

The multi-layer fuel tank obtained in Example 19 was finely divided using a crusher and pelletized by kneading at a temperature of 250 ° C using a coaxial twin-screw extruder. The particle diameter of the EVOH dispersed in the obtained pellet was examined using an optical microscope , and it was found that the average particle diameter was 30 µm (maximum 55 µm). The dry mixed mixture of 30% by weight of the pellets and 70% by weight of the HDPE (C) was obtained. Using the above mixture instead of the main material of Example 19 and the same adhesive and EVOH as in Example 19, a 3-type, 5-layer fuel tank was made in the same manner.

The physical properties of the obtained fuel tank were measured in the same manner as in Example 13. As a result, it was found that the initial adhesive strength was so strong that it was not possible to peel off, the degree of maintaining the adhesive strength was 100%, the difference in acoustic impedance was 19.8 x 10-2 g / cm2 µsec and h 1 / h 2; = 0.12; both, the properties and traceability were excellent.

Examples 23 to 34 and Comparative Examples 17 to 24

(1) Production of Modified Polyethylene

The various modified polyethylene resins used as adhesive components in the examples and comparative examples were produced as follows.

Modified PE (i)

To 100 parts by weight of a powder of HDPE (15) with a density of 0.950 g / cm³ and an MFR of 0.85 g / 10 min, 0.01 part by weight of 2,5-dimethyl-2,5-tert-butylperoxyhexane was added, the then dry blended for 2 minutes using a Henschel mixer. Then 0.35 part by weight of MAH was added and the mixture was dry blended for an additional two minutes. The mixture thus obtained was pelletized by melt kneading at a resin temperature of 260 ° C using an extruder. The amount of the grafted MAH in the obtained modified PE (1) was 0.32% by weight.

Modified PE (j)

Modified PE (j) was prepared by performing dry blending and melt kneading in the same manner as in the modified PE (i), except that instead of the HDPE (15) HDPE (15) used in the production of the modified PE (i) 16) with a density of 0.943 g / cm³ and an MFR of 0.40 g / 10 min. The amount of the grafted MAR in the modified PE (j) was 0.30% by weight.

Modified PE (k)

Dry mixing and melt kneading were carried out in the same manner as in the modified PE (i), except that instead of the HDPE (15) LLDPE (17) used in the preparation of the modified PES (i), it had a density of 0.924 g / cm³ and an MFR of 0.8 g / 10 min (melting point 120 ° C, number of ethylene group branches per 1000 carbon atoms of the main chain 10) was used. The amount of the grafted MAH in the modified PE (k) obtained was 0.28% by weight.

Modified PE (l)

Dry mixing and melt kneading were carried out in the same manner as in the modified PE (i), except that instead of the HDPE (15) L-ULDPE (18) used in the preparation of the modified PES (i), it had a density of 0.891 g / cm³ and an MFR of 1.8 g / 10 min (melting point 98 ° C, number of branches 70) and melt kneading was carried out at 230 ° C. The amount of the grafted MAH in the obtained modified PE (1) was 0.25% by weight.

In addition, ultra-low density, linear structure unmodified polyethylenes for use in the manufacture of the adhesive L-ULDPE (12), L-ULDPE (13) and L-ULDPE (14) of Example 13 (1) were used.

(2) Production of the adhesive

Modified polyethylene resin (modified PE), unmodified polyethylene resins (unmodified PE), and unmodified ultra-low density, linear structure (L-ULDPE) polyethylene resins whose type and blending amounts are shown in Tables 9 and 10 were dried under for five minutes in advance Mixed using a Henschel mixer. Each of the obtained mixtures was kneaded while being melted at a resin temperature of 210 ° C using an extruder. (Diameter 50 mm) to produce pellets (composition).

The density and acoustic impedance of the composition (adhesives) (33) to (49) were measured in the same manner as in Example 1. The results are shown in Tables 9 and 10.

(3) Manufacture of a multi-layer fuel tank

As shown in Tables 11 and 12, the aforementioned adhesives (33) to (49) were used as adhesives, and as the main materials, low pressure polyethylene resin (HDPE (D)) with an HLMFR of 5.0 g / 10 min, a density of 0.945 g / cm³ and an acoustic impedance (Z 0) of 2.23 x 10 &¹ g / cm² µsec and low pressure polyethylene resins (HDPE (E)) with an MFR of 0.5 g / 10 min, which has a density of 0.948 g / cm³ and Z & sub0; of 2.255 x 10 g / cm² µsec used.

In addition, nylon 6 (hereinafter referred to as "PA 6") with a relative viscosity of 4.2 was used as the polyamide resin.

A car fuel tank with an inner volume of 45 L and a total weight of 6.5 kg was blow-molded at 232 ° C using a multi-layer blow molding machine with a multi-layer die (concentric circular shape) equipped with the molding machine, by coextrusion of the main material and the adhesive thereof Types for each material are shown in Tables 11 and 12, and PA 6 manufactured in such a way that the thicknesses of the main material layer / adhesive layer / polyamide resin (PA 6) layer / adhesive layer / main material layer were 3.0 mm / 0.15 mm / 0.10 mm / 0.15 mm / 3.0 mm. Multilayer pieces with a width of 10 mm and a length of 150 mm were cut out from the flat portion of the obtained tank and their initial adhesive strength Po between the adhesive layer and PA 6 according to the T-type peeling method using a tensile tester under the conditions of a peeling speed of 50 mm / min measured, the results are shown in Tables 11 and 12.

In addition, after the same multilayer piece was left in an oven at 110 ° C for 72 hours, it was immersed at 40 ° C for 1,500 hours in a mixed solution containing 90% by volume of a commercially available common gasoline and 10% by volume of methyl alcohol. Then each piece was taken out and kept for 168 hours under the conditions of the temperature of 23 ° C and the relative humidity of 50%. After these treatments, the adhesive strength P & sub1; measured under the same conditions and the comparison with the previously measured P 1, the degree of retention of the adhesive strength (value of P 1 when P 0 is 100) was determined to evaluate the long-term heat resistance and the fuel resistance; the evaluation is shown in Tables 11 and 12.

In addition, the differences (ΔZ) in acoustic impedances between the main material layer and the adhesive layer were previously measured as h 1 / h 2. was mentioned, and the evaluation of the presence or absence of the detection based thereon was carried out in the same manner as in Example 1 with the results shown in Tables 11 and 12.

Example 35

The multilayer tank obtained in Example 30 was finely divided using a crusher and pelletized by kneading at a temperature of 265 ° C using a coaxial twin screw extruder. Observation of the dispersed particle diameter of PA 6 in the obtained pellet using an optical microscope showed that the average particle diameter was 45 µm (maximum 70 µm). A mixture comprising 30% by weight of the pellets and 70% by weight of a high molecular weight, low pressure polyethylene with a density of 0.94 g / cm³ and an HLMFR of 4.8 g / min was prepared by dry mixing. An automobile fuel tank was manufactured in the same manner as in Example 30, except that the one to which 1 part by weight of the high molecular weight, low pressure polyethylene had been dry blended. The detectability of the obtained tank was determined in the same manner as in Example 23 and h 1 / h 2. was 0.12; it is detectable. Table 11

* means cutting the layer comprising the main material layer and the adhesive layer. Table 12

* means that the spread is large.

Example 36

Using the adhesive (9) used in Example 9, low pressure polyethylene (HDPE (F)) with a density of 0.946 g / cm³ and an MFR of 0.3 g / 10 min as the main material and as the barrier material EVOH with an ethylene content of 30 mol%, a melting point by the DSC method of 188 ° C, an MFR at 230 ° C of 4.8 g / 10 min and a density of 1.19 g / cm³, became a 3-type 5-layer multi-layer blow container with a volume of 20 liters and such average thicknesses, that each of the inner and outer layers of the main material was 1.5 mm, each of the inner and outer layers of the adhesive was 0.10 mm, and the EVOH layer was 0.05 mm using a multi-layer blow molding machine equipped with extruders in each Diameter of 90 mm, 40 mm and 30 mm was equipped, and a 3-type-5-layer nozzle in a concentric circular shape.

An attempt to measure the adhesive strength between EVOH and the adhesive layers was made for the multi-layer piece cut from the flat portion of the obtained container, but without peeling. In addition, the piece was immersed in cooking oil containing linoleic acid as a main component at 40 ° C for 2500 hours and then tries to measure the adhesive strength between the EVOH layer and the adhesive layer in the same way. However, no peeling occurred and the excellent adhesive resistance was shown.

In addition, the above 20 liter multilayer container was upgraded to h 1 / h 2. measured, as a judgment for the detectability as above, using an ultrasonic wave of 20 MHz h 1 / h 2. = 0.12; excellent detectability was shown.

Industrial applicability

The multi-layer laminated molding of the present

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