Bonding polypropylene resin composition and multilayered laminated structure

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to adhesive polypropylene resin compositions and multilayer laminated structures. More specifically, an adhesive polypropylene resin composition suitable for adhering a polyolefin layer such as a polypropylene layer and a layer of a polyamide resin and / or an ethylene / vinyl alcohol copolymer and a multilayer laminated structure using the adhesive layer. Regarding.

【0002】

[Conventional technology]

Conventionally, laminated films of polyolefins such as polypropylene and polyamide resins and laminated films of polyolefins such as polypropylene and ethylene / vinyl alcohol copolymers have been known, and various adhesive layer materials for that purpose have been proposed. However, these materials have a significantly reduced adhesive strength in the stretching process when producing a shrink film, and do not always exhibit a sufficiently satisfactory adhesive strength.

【0003】

[Problems to be Solved by the Invention]

An object of the present invention is to provide an adhesive polypropylene resin composition that exhibits excellent adhesive strength to a polyolefin such as polypropylene and a polyamide resin and / or an ethylene / vinyl alcohol copolymer. Another object of the present invention is a multilayer laminated structure having an adhesive layer composed of the above-mentioned adhesive polypropylene resin composition of the present invention between a polyolefin layer and a polyamide resin layer and / or an ethylene / vinyl alcohol copolymer layer. Is to provide.

【0004】

Still another object of the present invention is to provide a multilayer laminated structure having an adhesive layer made of the above-mentioned adhesive polypropylene resin composition of the present invention, which exhibits excellent adhesive strength in both unstretched and stretched. ..

【0005】

[Means for solving problems]

According to the present invention, a modified polypropylene or a modified polypropylene-containing resin composition grafted with at least one monomer selected from (a) unsaturated carboxylic acid or a derivative thereof, 50 to 90 parts by weight and (b) unsaturated. Provided is an adhesive polypropylene resin composition comprising 10 to 50 parts by weight of a modified polyolefin other than the above (a) grafted with at least one monomer selected from a carboxylic acid or a derivative thereof. Further, according to the present invention, there are three layers in which a polyolefin layer, an adhesive layer made of the above-mentioned adhesive polypropylene resin composition, and a layer of a polyamide resin and / or an ethylene / vinyl alcohol copolymer are laminated in this order. The above-mentioned multilayer laminated structure is provided.

【0006】

[Preferable Aspects of the Invention]

In the adhesive polypropylene resin composition of the present invention, the polypropylene which is the material resin of the modified polypropylene of the component (a) has a propylene homopolymer or a propylene content having a melting point of more than 130 ° C and not more than 170 ° C. A copolymer of propylene having a content of 93 mol% or more and another α-olefin is preferably used. When a copolymer is used, examples of other α-olefins that are copolymerization components include ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and the like. .. The melt flow rate of polypropylene or copolymer (measured at 230 ° C according to ASTM D1238) is preferably 0.1 to 100, more preferably 0.5 to 50 g / 10 minutes.

【0007】

An unsaturated carboxylic acid or a derivative thereof is used as the graft monomer (hereinafter referred to as "graft monomer"), and specifically, the unsaturated carboxylic acid includes acrylic acid, methacrylic acid, maleic acid, fumaric acid, and the like. Itaconic acid and the like can be mentioned. Examples of the unsaturated carboxylic acid derivative include acid anhydrides, esters, amides, imides, and metal salts. Specifically, maleic anhydride, hymic anhydride (5-norbornen-2,3-dicarboxylic acid anhydride), itaconic anhydride, citraconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylic acid. Glycidyl, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl ester, itaconic acid monomethyl ester, itaconic acid diethyl ester, acrylamide, methacrylicamide, maleic acid monoamide, maleic acid diamide, maleic acid-N -Monoethylamide, maleic acid-N, N-diethylamide, maleic acid-N-monobutylamide, maleic acid-N, N-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monobutylamide, Examples thereof include fumaric acid-N, N-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate and the like. Of these graft monomers, maleic anhydride or hymic anhydride is most preferred.

【0008】

Polypropylene modified with an unsaturated carboxylic acid or a derivative thereof is preferably graft-modified with 0.05 to 15% by weight, more preferably 0.1 to 10% by weight of an unsaturated carboxylic acid or a derivative thereof based on the polypropylene before modification. .. The component (a) of the present invention may consist only of graft-modified polypropylene, or may be a composition of unmodified polypropylene and graft-modified polypropylene.

【0009】

As the modified polyrefin of (b), polyethylene, polybutene, ethylene / α-olefin copolymer (excluding ethylene / propylene copolymer having an ethylene content of 7 mol% or less) is used as a base resin, and unsaturated carboxylic acid or It is graft-modified with the derivative, preferably (i) having a density of 0.860 to 0.930 g / cm.³ , More preferably 0.860 ~ 0.905g / cm³, (Ii) melt flow rate (MFR) at 190 ° C, 2.16 kg load 0.1-50 g / 10 min, more preferably 0.1-10 g / 10 min, and (iii) graft ratio 0.01-5 wt%, more It is preferably a modified polyethylene or a modified ethylene / α-olefin copolymer having a weight of 0.3 to 3% by weight. More preferably, it is a modified polyolefin using a substantially amorphous or low crystallinity ethylene / α-olefin copolymer or the like as a base resin.

【0010】

The base resin before modification of the graft-modified ethylene / α-olefin copolymer (b) is more preferably a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Of these, as the α-olefin, an α-olefin having 3 to 10 carbon atoms is preferable. As the α-olefin, for example, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and the like can be mentioned as preferable ones. The ethylene / α-olefin copolymer (b) before modification can be produced by a conventionally known method using a catalyst such as titanium (Ti) -based, vanadium (V) -based, or zirconium (Zr) -based catalyst. ..

【0011】

Further, the ethylene / α-olefin copolymer (b) preferably contains a polymerization unit derived from ethylene in an amount of 95 to 70 mol%, more preferably 90 to 75 mol%. The ethylene / α-olefin copolymer (b) is substantially amorphous or low in crystallinity, and preferably has a crystallinity (measured by an X-ray diffraction method) of less than 40%.

【0012】

Various known methods can be adopted for graft-copolymerizing the graft monomer with polyolefin to produce a modified product. For example, there is a melt modification method in which polyolefin is melted using an extruder and a graft monomer is added to carry out graft copolymerization, or a solution modification method in which a polyolefin is dissolved in a solvent and a graft monomer is added to carry out graft copolymerization. In any case, in order to efficiently carry out graft copolymerization of the graft monomer, it is preferable to initiate the reaction in the presence of a radical initiator. The graft reaction is usually carried out at a temperature of 60 to 350 ° C. The ratio of the radical initiator used is usually in the range of 0.001 to 1 part by weight with respect to 100 parts by weight of the polyolefin. Examples of radical initiators include organic peroxides, organic peroxides such as benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (peroxide benzoate) hexin-. 3,1,4-bis (tert-butylperoxyisopropyl) benzene, lauroyl peroxide, tert-butylperacetate, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexin-3,2,5- Dimethyl-2,5-di (tert-butylperoxy) hexane, tert-butylperbenzoate, tert-butylperphenylacetate, tert-butylperisobutyrate, tert-butylper-sec-octate, tert-butylperpivarate , Cumylperpivalate and tert-butylperdiethyl acetate, and other azo compounds such as azoisobutyronitrile and dimethylazoisobutyrate are used. Of these, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (peroxybenzoate) hexyne-3, 2,5-dimethyl-2,5-di (tert-butyl) Peroxy) Hexane, 1, Dialkyl peroxides such as 4-bis (tert-butylperoxyisopropyl) benzene are preferred. Other monomers such as styrene may coexist in the reaction.

【0013】

The amount of the graft monomer grafted onto the polyolefin (hereinafter referred to as the "graft ratio") is such that the graft ratio of the entire composition is 10.^-4It is preferable to adjust it so that it is in the range of ~ 5% by weight. From the viewpoint of industrial manufacturing, the graft rate is 10 in advance.^-2A method of producing ~ 6% by weight of the modified polyolefin and then mixing the modified polyolefin with the unmodified polyolefin to adjust the graft ratio is preferable because the amount of the graft monomer in the composition can be appropriately adjusted. However, a predetermined amount of graft monomer may be added to the polyolefin from the beginning.

【0014】

In the case of polyethylene or an ethylene / α-olefin copolymer, either the melt modification method or the solution modification method can be adopted, but in the case of polypropylene, the solution modification method is preferable from the viewpoint of graft reaction efficiency and suppression of decrease in molecular weight.

【0015】

The components (a) and (b) are based on a total of 100 parts by weight of these components, and the component (a) is 50 to 90 parts by weight, preferably 50 to 80 parts by weight, and the component (b) is 10. It is contained in an amount of to 50 parts by weight, preferably 20 to 50 parts by weight. The composition of the present invention containing the components (a) and (b) preferably has a melt flow rate (ASTM D1238, 230 ° C) of 0.5 to 30 g / 10 minutes, preferably 1 to 10 g / 10 minutes. Is more preferable.

【0016】

The adhesive polypropylene resin composition of the present invention exhibits excellent adhesive strength to polyolefin resins such as polypropylene resin, polyamide resins and ethylene / vinyl alcohol copolymers. Therefore, according to the present invention, secondly, it is a multilayer structure in which a polyolefin layer such as polypropylene, an adhesive layer and a layer of a polyamide resin and / or an ethylene / vinyl alcohol copolymer are laminated in this order. Similarly, a multilayer laminated structure in which the adhesive layer is made of the adhesive polypropylene resin composition of the present invention is provided.

【0017】

The multilayer structure of the present invention has at least three layers, the first layer is a polyolefin layer (A), the second layer is an adhesive layer (B), and the third layer is a polyamide resin and / or ethylene / vinyl alcohol. It is a layer composed of the polymer (C). For example, it is a combination of A / B / C, A / B / C / B, A / B / C / B / A, and the like.

【0018】

A polypropylene resin layer can be typically mentioned as the polyolefin layer of the first layer, and examples of the polypropylene resin constituting the layer include a homopolymer of propylene, propylene having a propylene content of 93 mol% or more, and other polypropylene resins. It may be a copolymer with α-olefin. Examples of other α-olefins include ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and the like.

【0019】

The adhesive layer of the second layer of the multilayer structure of the present invention comprises the above-mentioned adhesive polypropylene resin composition of the present invention.

【0020】

The third layer of the multilayer structure of the present invention comprises a polyamide resin layer and / or an ethylene / vinyl alcohol copolymer. As the polyamide resin, for example, nylon 6, nylon 66, nylon 610, nylon 12, nylon 11, MXD nylon, amorphous nylon, terephthalic acid / adipic acid / hexamethylenediamine copolymer and the like can be preferably used. The ethylene / vinyl alcohol copolymer preferably has an ethylene content of 20 to 50 mol%. The ethylene-vinyl alcohol copolymer can be prepared by saponifying ethylene and vinyl acetate copolymer.

【0021】

The multilayer structure of the present invention can be produced by laminating a polypropylene layer, an adhesive layer, and a layer of a polyamide resin and / or an ethylene / vinyl alcohol copolymer in a molten state. The multilayer laminated structure can be produced, for example, by coextrusion molding, cast film molding, inflation film molding, a tenter method, a tubular biaxial stretching method, or the like. Normally, the stretching conditions for producing a shrink film are a stretching temperature of 70 to 130 ° C, a stretching ratio (length x width) of 2 x 2 to 5 x 5 times, and a obtained film thickness of 10 to 200 μm. ..

【0022】

The multilayer laminated structure of the present invention can be used as it is in an unstretched state after molding, or can be stretched in at least a uniaxial direction, preferably a biaxial direction after molding. When the third layer is a polyamide resin layer, it is preferably stretched and used, and when the third layer is an ethylene / vinyl alcohol copolymer layer, it can be used in either an unstretched state or a stretched state. Since high strength can be obtained by stretching, it is preferable to stretch and use it when high strength is required. However, by stretching, the adhesive strength of the adhesive layer is generally slightly reduced. Even when the multi-layer laminated structure of the present invention is stretched, the adhesive strength is not significantly reduced and a sufficiently practical adhesive strength is maintained. It is desirable to carry out stretching at least in the uniaxial direction at a stretching ratio of 1.5 to 6 times. In biaxial stretching, it is preferable to stretch in each biaxial direction at a stretching ratio of 1.5 to 6 times.

【0023】

When the multilayer laminated structure of the present invention is cast-molded by the T-die method, the stretched product is formed by molding at a relatively high molding speed, for example, 20 m / min or more, preferably 20 to 150 m / min. It is possible to obtain a multi-layer laminated structure exhibiting film strength and adhesive strength having the same tendency as the above. The multi-layer laminated structure of the present invention is excellent in strength, heat resistance, gas barrier property, and can also impart shrinkage, so that it can be suitably used for packaging meat such as ham.

【0024】

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited by these examples. In the present invention, the "graft ratio" of the graft-modified polypropylene (a), the graft-modified polyolefin (b), etc., including the following examples, is 1792 cm by an infrared spectroscopic measuring device.^-1Or 1860 cm^-1Absorbance and 4335 cm^-1Measure the absorbance of (1792 cm)^-1Or 1860 cm^-1Absorbance measurement value) / (4335cm^-1(Measured value of absorbance) was obtained, and the graft ratio was obtained from the value of this ratio using a calibration curve chart prepared in advance.

【0025】

[Example 1] Polypropylene / ethylene random copolymer (r-PP; ethylene content: 3.6 mol%, melting point: 139 ° C, MFR (230 ° C) = 6 g / 10 minutes) 85 parts by weight and maleic anhydride Graft-modified polypropylene (MAH-PP; maleic anhydride graft amount: 3% by weight, extreme viscosity in decalin solvent 135 ° C [η] = 0.4dl / g, melting point 160 ° C) 5 parts by weight and maleic anhydride graft modification Made with ethylene-butene copolymer (MAH-EBR; V-based catalyst, butene content: 10 mol%, maleic anhydride graft amount: 0.5% by weight, MFR (190 ° C) = 5 g / 10 minutes, melting point 70 ° C) 10 parts by weight were mixed with a Henshell mixer and then melt-kneaded with a uniaxial extruder (set temperature: 230 ° C, special darmage screw) to obtain a modified polypropylene resin composition. Then, using this composition, the adhesive strength with the ethylene / vinyl alcohol copolymer and the polyamide resin was measured by the following methods.

【0026】

(I) Method for evaluating adhesive strength with ethylene / vinyl alcohol copolymer Ethylene vinyl alcohol copolymer (EVOH; trade name EVAL EP-E105, manufactured by Kuraray Co., Ltd., MFR: 5.5 g / 10 minutes, ethylene content: 44 mol%), the modified polypropylene resin composition and the above r. -Using PP, a 3-layer cast film was formed under the following conditions. Film layer composition: EVOH (outer layer) / composition (intermediate layer) / r-PP = 40/40 / 160μ (II) Method for evaluating adhesive strength with polyamide resin A three-layer cast film was molded under the following conditions using a polyamide resin (PA; trade name: Amylan, manufactured by Toray Industries, Inc.), the modified polypropylene resin composition, and the r-PP. Film layer composition: PA (outer layer) / composition (intermediate layer) / r-PP = 40/40 / 160μ [0027]

The obtained three-layer films (I) and (II) were heated at 80 ° C for 10 minutes using a biaxial stretching device manufactured by Toyo Seiki Co., Ltd., and then tripled in the vertical direction and in the horizontal direction at that temperature. A three-layer stretched film was prepared by simultaneously biaxially stretching the film three times. Subsequently, after cooling to room temperature, the interfacial adhesive strength between the EVOH layer or polyamide layer of each three-layer stretched film and the composition was determined by T-type peeling at a peeling speed of 300 mm / min. The results are shown in Table 1.

【0028】

[Examples 2 and 3] The blending ratios of the propylene / ethylene random copolymer (r-PP) blended in the modified polypropylene resin composition in Example 1 are 75 parts by weight (Example 2) and 65 parts by weight, respectively. (Example 3), except that the blending amounts of the maleic anhydride graft-modified ethylene / butene copolymer (MAH-EBR) were 20 parts by weight (Example 2) and 30 parts by weight (Example 3), respectively. A modified polypropylene resin composition was prepared by treating in the same manner as in Example 1, and the adhesive strength thereof was evaluated by the same method as in Example 1. The results are shown in Table 1.

【0029】

[Example 4] Maleic anhydride graft-modified ethylene / propylene copolymer (MAH-EPR; produced with V-based catalyst, propylene content: 20 mol%, maleic anhydride instead of MAH-EBR used in Example 2 The same procedure as in Example 2 was carried out except that the amount of graft: 0.5% by weight, MFR (190 ° C) = 3 g / 10 minutes, and melting point 40 ° C) was used. The results are shown in Table 1.

【0030】

[Example 5] Maleic anhydride graft-modified ethylene-octene copolymer (MAH-EOR; produced with Zr-based catalyst) instead of MAH-EBR used in Example 2, octene content: 15 mol%, maleic anhydride The same procedure as in Example 2 was carried out except that the amount of graft: 0.5% by weight, MFR (190 ° C) 3 g / 10 minutes, melting point 55 ° C) was used. The results are shown in Table 2.

【0031】

[Example 6] Examples except that a propylene homopolymer (h-PP; melting point: 165 ° C, MFR (230 ° C) = 6 g / 10 minutes) is used instead of r-PP used in Example 3. It was done in the same way as 3. The results are shown in Table 2.

【0032】

[Example 7] Maleic anhydride graft-modified polyethylene (MAH-PE; 0.92 g / cm) instead of 30 parts by weight of MAH-EBR used in Example 3.³ , Manufactured with Ti-based catalyst, Maleic anhydride Graft amount: 1.0% by weight, MFR (190 ° C) = 0.5g / 10 minutes, melting point 122 ° C) 10 parts by weight and unmodified ethylene-propylene copolymer (EPR; It was produced in the same manner as in Example 3 except that it was produced with a V-based catalyst, propylene content: 20 mol%, MFR (190 ° C) = 3 g / 10 minutes, and 20 parts by weight of melting point 40 ° C). The results are shown in Table 2.

【0033】

[Example 8] The same as in Example 3 except that the MAH-EBR 15 parts by weight used in Example 3 and the EPR 15 parts by weight used in Example 7 were used instead of the MAH-EBR 30 parts by weight used in Example 3. went. The results are shown in Table 2.

【0034】

[table 1]

<img file="JPH09111069A_D0001.tif" />【0035】

[Table 2]

<img file="JPH09111069A_D0002.tif" />【0036】

(Comparative Example 1) The r-PP and MAH-PP used in Example 1 were used in the ratios shown in Table 3, and the same procedure as in Example 1 was carried out except that MAH-EBR was not added. The results are shown in Table 3.

【0037】

(Comparative Examples 2 and 3) The amounts (parts by weight) of r-PP and MAH-PP used in Example 1 were used respectively, and 10 parts by weight of MAH-EBR blended in Example 1 was not blended. Instead, EPR (unmodified ethylene / propylene copolymer) of Example 7 was blended in an amount of 20 parts by weight (Comparative Example 2) and 30 parts by weight (Comparative Example 3), respectively, in the same manner as in Example 1. The results are shown in Table 3.

【0038】

[Table 3]

<img file="JPH09111069A_D0003.tif" />【0039】

[Effect of the invention]

According to the present invention, it is possible to provide an adhesive resin composition exhibiting excellent adhesive strength to a polyolefin resin such as polypropylene resin, a polyamide resin and an ethylene / vinyl alcohol resin, and a multilayer laminated structure using the adhesive layer.