Composite coextruded polymeric material

The present invention relates to a vinylidene polyfluoride based coating and Ta -im process for obtaining it by coextrusion. '

The technique of co-extrusion of thermoplastic materials is well known.

- · - 'For the coextraction of thermopia.stice materials, generally, three processes are known, using' conventional extruders 'in number equal to' the number of polymers to be extruded.

The first process consists in the separate extrusion of polymers and their reunion at the exit of the die. The second choreographic process in feeding a single die I help at least two extruders, the die being equipped with extrusion channels. The flow of polymers s <e ^ meets, at the level 1, the lips of the die, so near the exit of this die. The third process consists of feeding a flow distributor With the help of a desired number of extrusion. In this apportionment, the polymers meet in a single stream, which feeds the chain. In this process, the respective extruding rates allow,> usually, the adjustment; the relative thickness of extruded polymers. mm ,,^;m

With all extruded

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that many polymers can be joined together by other polymers, vinylidene polyfluoride could be combined with other polymers ou this technique. The fact is due to the lack of its compatibility with other polymers, as well as the lack of adhesion of the fluorinated resins. Most of the polymers tend to be moplastic, Thus, for the coating of vinylidene polyfluoride with other thermoplastic polymers, “by removing two films made previously, vinyl emulsion, , the other material ₁₅ thermoplastic of vinylidene, the other of the thermoplastic material, respectively for the adhesion between¹ the two films, the hot press is applied; such tests have been carried out starting from a film of prefabricated vinylidene polyfluoride and other vinyl polychloride, polystyrene, methyl tetracrylate or an aerilonitrile-butadiene-styrene copolymer in a practically melted state. Even in these cones₂₅ you say, after all. cooling, the two films are slightly separated.

c Also, in the present state of the art, :: when it is desired &lt;the association of vinylidene polyfluoride with another one: tere polymer, • 78589. -, ·.

.THE PRICE 12.47

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&lt;, // moplastic, iiecpnipatihily 'it is necessary to' S &lt;T break the binder. ' This process has drawbacks, because it is complex, involving three mandatory phases: preparation of vinylidene polyfluoride film; -_r film preparation of thermoplastic material; -^;'bonding and pressing them.

These operations are slow, generally requiring the use of solvent based binders, which are! difficult to remove_?!and, no, they allow the immediate use of the composition in a timely manner, necessary for drying ^:adhesive. On the other hand, the resulting stratum is devoid of unity, the interfaces still remaining susceptible to detachment. consequently, it can be stated that, by gluing, a horn is not obtained (unitary position, but an overlapping filling;

Polyfluoride based laminate; vinylidene; 'and vun incompatible polymer - with it, chosen from three polyvinyl chloride, acrylonitrile terpolymer' Pbutadiene-styrene, having two or more alternating layers, the two outer surfaces being different, eliminating the mentioned disadvantages, / prip-, water, that, · in, purpose. assurance of compatibility between the 'alternating layers, contains one or more' intermediate layers of polyalkylmethacrylate or its copolymer, with an icopenut.tie ^ ipinRaym ,, .30¾ jn, .greutate 'polialchdmetacrRaP-p Pp9pediaubatuat: steatobat, stentobate , to him, .QQnș.t.a.acea.acea.cif polyfluorpra ^ and yi "pilideu, · the polymer. incompatible · with.poeas »knows, - as well as between them -> -polialLphiln ^ etecrylate, · ... se.extrud. Individual ',. .fpjiile. .the results ·· overlap and '. , then "they are ... cnextindate", at the temperature -de. , 140 ...

• 1.5, here below. Invention of the invention. . . ·, · ·; ^ Example ;. 1.:· Șe ι, uses three-, extru_rFor (,. The term is: provided with a system. 4e .-. dega ^ age,_;It has a diameter of 12 0 mm and the length of the screw is equal to. 33 "/ times: its diameter. Eg - it is used for the extrusion of the copolymer> npriloniprriPbu_Qtadjesd-sțmom- (ABS) and · .. second -.are, _f djâipxețrul dp_: 50., mm and-is used for ^ xțrpdeţpa_ţ the polymethylpyrilate of methyl, (PtylJvțÂ) .- ϋΐ; third,. it has the diode of - 40o mim and ise - uses c. to, - the extrusion of pdlifluoriirii · t) <de 'vini r .țBVEaJe-¹ These three extruders feed a flow-cylinder, which is fixed to itself: 'on a' Qplata 'A / A' for use in manufacturing, and a --flid «feMlrâa ·· 4'uium-thickness, impacted by a calender and an elastic pull train for¹ plate extrusion.

? dd.-The viscosity of the ABS measured 'at tem'peraLura of 2? 0 ° C is 75 χ IO³ poise at a speed gradient of 5.6 s^_1and 10 χ 10 'poise at a gradient of 2^_1.

The measured PMMA viscosity at 200 ° C is -110 χ 10 'poise at a velocity gradient of 5.6 s ~¹ and 14 X 10 ': at a gradient of 2 s ~ A The viscosity measured at ^ OO ^ Î of the vinylidene fluorescence is T4l · jR 10® and 8.8 .X-10? tP, for speed gradients, 3.5 s^-', respectively 354 s "¹.

The heating temperatures of the extruders range from 190 to 210 ° C for ABS, from 180 to 200 ° C for PMMA and, from: to 18O, .: 22O ° C for vinylidene polyfluoride. . ·; '· -M ·' Repair the flow shelf is maintained ....... at 210'C and 'the same is the chain.

The film is passed between ...... the cylinders of one. heated calenderer at 80 ° C. The total flow is about 300 kg / h. By:: the bit '' of these three extrusions t.se: adjusts so-. So that it is obtained in: .final o? composition comprising ABS of thickness 4, mm, PMMA of thickness 30 a and a PVFy of thickness 100 μ. These three layers are perfectly fused balls between the release of .rdin Jiljeră, After cooling, ·: get-_;one layer (P-coated with homogeneous structhra, one of which is made of vinylidene polyfluoride and the other is acryl-nitrile-biitadiene-styrene copolymer.

... Example, 2._; SE. works under the conditions of .example 1,_r used. - a - flow distributor, so Incit. the exit of the drill to obtain a "stratified.

.. five layers. , Șe, - use .ti.aceiașl / pofimeri and the same temperatures - with and in the example li.It results "a. Stratified ,, in-, giving. s features. - <âu The following sequence1 nn layer of .7 5 days. .of vinylidene. (P.VFa),. .a. stratum-de.-50 μ-. of ΡΜΜΙΑ,. / ρη strat. of 3, now of ABS,. .a layer of .50 μ, -de. PMMA and, In Rne, .. a, .strat._:of R75 H of PVF .; The stratified one, porch. five / keep. f mp. perfectly - supplied between them. It breaks everything, wax, resulting in a truncated μη: i construction. homogeneous. · possessing; · external vinylidene polyfluoride double seams. and between ABS and PMMA. '·' ,, Exenipiuln ^ - '; It? ' uses an extruder., with screw, double penton. You spray the vinyl chloride (PVC) chloride, an extruder with a diameter of: 3 / mnm for> 3;^;(PMMA)^; and · an extruder with¹ -10- mm- diameter for tic vinylidene fluoride poly. · Η: Μ: η. ··,; · η '/ l - · ΰ

These extrusion feeds · feed the flow distributor^:And he: fixed himself. Water a head of the extrusion tube. The installation is also provided with an apparatus for measuring the dimensions under vacuum and with a classic drawing system.

All three polymers are coextruded as follows: at the temperature of 100 ... 20 ° C vinyl polychloride, 180 ... 200 ° C methyl polymethacrylate and at 18 O ... 2OO ° C vinylidene polyfluoride. The extruder head is maintained at 195 ... 200 ° C, as is the flow distributor.

A tube with an outer diameter of 50 mm is obtained, consisting successively of a layer of vinyl polychloride of about 3 mm thick, a layer of PMMA of about 50 mm thickness and an intermediate layer of about 75 i. Thick of vinylidene polyfluoride. . The three polymers are in the form of a homogeneous and uniform layer.

Example 4. Use of a set of three extruders, as in example 3, provided with a flow distributor and with an extrusion head of the tube. The installation also includes a classic melting and blowing system, which allows a blown co-extrusion of the three polymers. In the first extruder, vinyl polychloride is introduced, in the second extruder, PMMA is introduced and in the third extruder, vinylidene polyfluoride is introduced. The extrusion temperatures are: 16O ... 18O ° C,

18O ... 19O ° C and 190 ... 200 ° C, respectively. The flow dispenser and the outlet lip have a temperature of 190 ° C.

An extrudate is obtained which is blown in the classical manner to obtain a vial. The three extruders were fixed to the flow distributor in such a way that the vial has an outer coating of about 100 of vinylidene polyfluoride, an intermediate layer of about 80 μm PMMA and finally a layer of polyvinyl chloride. about 8/10 mm thick.

The three layers of the vial obtained are perfectly fused together at the outlet head of the extruder. After cooling, the vial is in the form of a layer with a homogeneous and unitary structure.

Example 5. Three extruders are used, the first provided with a degassing system, with a diameter of 120 mm and a screw length equal to 33 times its diameter. It can be used to extrude the acrylonitrile-butadiene-styrene copolymer, the second with a diameter of 50 mm for the following polymer mix: methyl polymethylacrylate (PMMA): 40 parts, vinylidene polyfluoride (PVF)₂) 30 parts, 30 parts ABS and third with 40 mm diameter for vinylidene polyfluoride (PVF₂).

These three extruders feed a flow-distributing cylinder, which is fixed in 6 sockets to a regular flat die, intended to manufacture a plate approximately mm thick, a calender and a classic pull train for plate extrusion.

The viscosity of the ABS is measured at 220 ° C and is 75 X IO³ poise, at the velocity gradient of 5.6 s^them and 10 X IO³ poise at the gradient of 2 s^—The viscosity of the PMMA, measured at 200 ° C, is 110x10 ', at the gradient of V6 s¹and · 14 χ IO³ at the gradient of 2 s'. The viscosity measured at 200 ° C of vinylidene polyfluoride is 141 X IO³ poise and 8.8 χ IO³ poise for speed gradients of 3.5 respectively 354? / 1

The heating temperatures of the extruders range from 190 to 200 ° C for mixtures containing PMMA and from 180 to 200^GC for mixtures containing vinylidene polyfluoride.

The flow distributor is at a temperature of 210 ° C, as is the chain. The film is passed through the cylinders of a calender heated to 80^ofC.

The total flow is about 300 kg / h. The flow rates of the three extruders are adjusted to obtain, finally, a layer containing ABS in thickness of 4 rpm |, PMMA of about 30 μm and PVF> 100 μm. These three layers are perfectly fused together at the exit of the die. . After cooling, it results in a layer with a homogeneous structure, one side being made of vinylidene polyfluoride and the other one is ABS.

Example 6. Work in the same conditions as in Example 5, however, replacing the mixture containing PMMA with the following mixture: 30 parts by weight PMMA, 40 parts by weight polyacrylic derivative and 30 parts by weight ABS, obtaining a laminate with homogeneous structure, in which the layers are perfectly fused with each other from the exit of the die and to which the faces are made of vinylidene polyfluoride and the other one made of ABS.

The laminate obtained according to the present invention usually has three alloy components of vinylidene alkyl-polyfluoride polymethacrylate and thermoplastic alkyl-polymethacrylate polymer, incompatible with polyvinylidene fluoride, the laminate having at least one outer surface. and a thermoplastic polymer surface incompatible with vinylidene polyfluoride. This stratified, for reasons mainly of economy, generally has only one external face of vinylidene polyfluoride, the other external face being represented by the thermoplastic polymer incompatible with polyvinylidene fluoride. At the same time, the thermoplastic polymer incompatible with vinylidene polyfluoride can serve as a bonding base with another material. It is, therefore, possible that the laminate, according to the present invention, possesses the two outer faces of vinylidene polyfluoride according to the succession of the alloys following the three elements: PVCz-polymethylacrylate of thermoplastic alkylpolymer incompatible with vinylidene-polymethylacrylate of alkyl-polyphenol fluoride.

Such a product, which can be found in all ordinary forms of thermoplastics, such as, for example, tubes, heels, profiles, films, plates, the latter being convertible according to known techniques, such as thermoforming, has a of great interest because it has at least one weatherproof outer face and generally all the own properties of vinylidene polyfluoride and the other side having all the mechanical properties of thermoplastic polymers incompatible with vinylidene polyfluoride and this in the form of a unitary and structurally homogeneous material.

Such material is obtained by co-extrusion and this is even more surprising⁵ as far as the great difficulty of being able to adhere vinylidene polyfluoride to a thermoplastic polymer is known. It was found that, if an alkyl polymethacrylate is coextruded, at the same time as vinylidene polyfluoride and thermoplastic material incompatible with it, in such a way that the polymet,_c the crate to be located between the two poles 10 apples, in time an immediately usable material is obtained, in which all the layers are tightly joined by each other.

Although all vinylidene polyfluorides give more or less satisfactory results, the best results are obtained with vinylidene polyfluoride which is in a viscosity range of²⁵ relative to 200 "C, as the one presented with at least two velocity gradients in the table below, having the apparent viscosities, respectively included, between the two extreme apparent viscosities indicated (table 1).

Table 1

<td rowspan="2">Speed ​​gradient</td><td colspan="2">The value of the apparent viscosity in Poise</td>

<td>minimum</td><td>maximum</td>

<td> 3,54</td><td> 30,10*</td><td> 200 10-'</td>

<td> 11,81</td><td> 18,10^:it</td><td> 93 10ⁱ</td>

<td> 35,4</td><td> 11,10³</td><td> 47 10-</td>

<td> 118</td><td>6.5 IO³</td><td> 21 10ⁱ</td>

<td> 354</td><td> 3,9 10’</td><td> 30 10-</td>

<td> 1181</td><td> 2,3 10-</td><td> 4,5 10ⁱ</td>

The apparent viscosities referred to are measured in the known manner, with the help of the rheometric capillary, taking into account Rabindwitch's correction applied to Newtonian liquids.

Although the thickness of the vinylidene polyfluoride layer is unimportant, it is preferable, for economic reasons, to make the material composition at which the layer thickness is between 10 μ and several tens of mm. equally, it is understood to mean vinylidene polyfluoride not only monopolyrenes, but also copolymers containing at least 70% by weight vinylidene polyfluoride, as well as the mixture of vinylidene polyfluoride with other polymers,

The alkyl polymethacrylate (PMMA), used in accordance with the invention, is preferably a methyl polymethacrylate, wherein the melt viscosity can be chosen in the range of viscosity PMMA technically, possibly increasing the viscosity at will.⁴⁰ the desired amount, being achieved by mixing, for example, with small quantities of batches, provided that at least 75¾ by weight of polymers are kept45 alkyl lacrylate.

On the other hand, it was found that this is in. depending on the viscosity in the · melted state of the material, thermoplastic-incompatible and that function.of it-the quality of the polymethylacrylate of alkyl and, - - possibly, of the polyfluoride of vj, nil.- must be chosen. &lt;Good results were obtained with a viscosity of methyl polymethacrylate within the limits indicated for the velocity gradient presented below and measured at a temperature of 200^cC. At the same time, these values ​​are not limiting and the viscosities will be according to the extrusion temperature (table 2),

Ibeltibelwl 2

<td rowspan="2">'Gradient of, speed, s—¹</td><td colspan="2">The value of the apparent viscosity in Poise</td>

<td>minimum</td><td>maximum</td>

<td>¹ 3,54</td><td>100 X IO³</td><td>500 X IO³</td>

<td> 11,81</td><td>50 X IO³</td><td>200 X IO³</td>

<td> 35,4</td><td>25 X IO³</td><td>150 X IO³</td>

<td> 118,0</td><td>13 X IO³</td><td>80 X IO³</td>

<td> 354</td><td>7 X 10³</td><td>50 X IO³</td>

<td> 1181</td><td>3.5 X 10³</td><td>30 X IO³</td>

Equally, it is possible to associate at least one other thermoplastic polymer by mixing with alkyl polymethacrylate, provided that this mixture contains at least 30% by weight of alkyl polymethacrylate. The polymer that binds to the alkyl polymethacrylate can be chosen from the following products: thermoplastic polymers! fluorinates, chlorinated vinyl polymers, 1 ° styrene polymers, polycarbonate, polyurethanes, polyesters, styrene-acrylonitrile-elastomer copolymers, acrylic graft, acrylonitrile-butadiene-styrene copolymer, polyacrylate or polyacrylate, polyacrylate of butyls, or copolymers of these acrylic esters with, for example, vinyl derivatives, or copolymers of alkyl methacrylate with, for example, vinyl chloride, vinyl acetate, methyl acrylate, styrene, isobutylene, acrylic acid, acrylonitrile and methacrylonitrile. ³⁰

The thickness of the alkyl polymethacrylate is adjusted, as the case may be, between a few microns and 200 μm thick. In general, it is not advisable to operate with greater thicknesses 35, because of the importance taken by alkyl polymethacrylate within the overall mechanical properties.

Thermoplastic polymer incompatible with 4₀vinylidene polyfluoride may be selected from chlorinated vinyl polymer, such as vinylidene or polychloride, from vinylidene, a styrene polymer, such as polystyrene or polystyrene-shock, polycarbonate, polyurethane, styrene copolymer. acrylonitrile-elastomer acrylic grafted, acrylonitrile-butadiene-styrene copolymer. The thickness of the thermoplastic polymer layer can be any and usually from a few tenths of microns to several millimeters. Of course, the thermoplastic polymer may contain adjuvants, such as plasticizers, stabilizers, dyes.

The installation used to obtain the laminate, according to the invention, is composed of extrusion, die-cast and, preferably, a classical flow distributor and commonly used in the extrusion and co-extrusion technique of thermoplastic masses. The thickness of each layer is regulated by the flow rate of each extruder.

To achieve the invention, the temperature of the die is between 180 and 200''C, this temperature displacing the materials subjected to the extrusion process, respectively coextrusion. The temperatures of the extruders are those usually provided for the simple extrusion of each individual polymer.

In order for the final cohesion between the three polymers to be well ensured, it is recommended that the three polymers be coextruded in such a way that the extruding materials are later assembled at the lips of the die. In some cases, the cohesion obtained may leave it to be desired, because it is preferable that the flow of vinylidene polyfluoride, thermoplastic polymer and alkyl polymethylacrylate at the extruder exit to work together, over a certain length, before 5 by entering the lips of the chain. In the latter case, instead of a multichannel channel, a flow distributor is interposed between the extruder output and a single channel channel.¹¹

The present invention has advantages in that, in a simple and easy way, a laminate, based on vinylidene polyfluoride, is obtained and a polymer incompatible with it, layered, with a unitary composition.