WO2010052262A1 - Films with high resistance to styrene - Google Patents

Abstract

The present invention relates to films made of polyamide-based or polyester-based thermoplastic molding materials and an olefin-acrylate copolymer, said films having high resistance to styrene. The invention also relates to uses of said films as separating films for covering cast resins or cast resin products containing styrene.

Description

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Films with increased resistance to styrene

The present invention relates to films of thermoplastic molding compositions based on polyamides or polyesters and an olefin-acrylate copolymer with increased resistance to styrene and their uses as release films for covering styrene-containing casting resins or cast resin products.

Fiberglass mats impregnated with styrene-containing casting resin (Sheet Molding Composites, SMC for short) are a common commercial form of custom-made semi-finished products for use in shipbuilding, in the production of liquid tanks or in the construction of other shaped bodies. The semifinished products impregnated with styrene-containing resin solutions must be externally supported Separating films are covered to prevent the escape of the liquid resin solution, the evaporation of the volatiles contained therein and an entry of impurities. Release films are therefore required for safe handling and processing of casting resins or resin-impregnated fiberglass mats.

EP-A-0 372 866 describes a process for the preparation of SMC composites using films made from an extruded mixture of a C 2 -C 20 alpha olefin copolymer and an aliphatic polyamide, wherein the alpha olefin copolymer is grafted with a grafting monomer Other selected from acrylic acid or methacrylic acid.

US-A-4 444 829 discloses an SMC release film of blends of polyamide 6 and copolymers of ethylene-ethyl acrylate or ethylene-methyl acrylate.

The disadvantage of the materials known from the prior art is not always satisfactory chemical resistance with the associated permeability to volatile components as a result of chemical attack of the release films by constituents of the casting resin and the formation of pores.

Therefore, the object was to produce release foils for semi-finished liquid resin impregnated glass fiber mats, which are characterized by improved chemical resistance, which is characterized by a reduced permeability to volatile constituents of liquid casting resin. For this purpose, the permeability of the films prepared from the compositions according to the invention is to be considered for styrene, since styrene is the main constituent of the volatiles in the casting resin with which the glass fiber mats used in said semifinished products are impregnated. - -

It has now surprisingly been found that films of thermoplastic molding compositions based on polyamides or polyesters and an olefin-acrylate copolymer have improved chemical resistance with an associated improved barrier effect of the films produced therefrom for volatile constituents of casting resin. The use of an olefin-acrylate copolymer of the type according to the invention leads to an improved, i. reduced permeability of the films for styrene. In addition, the increased barrier effect of the release films from the molding compositions according to the invention for atmospheric oxygen leads to an improved curing result of styrene-containing casting resins due to the lack of oxygen-based polymerization inhibition in the outer resin layer. The casting resin molding thus cures completely on the air-facing side to below the release film, whereby a stickiness of the resin surface is avoided after curing.

The invention therefore SMC release films based on thermoplastic molding compositions of polyamides or polyesters, characterized in that the thermoplastic molding compositions contain at least one random copolymer of at least one olefin, preferably α-olefin and at least one acrylic acid ester of an aliphatic alcohol, wherein the MFI ( Melt Flow Index) of the copolymer B) is greater than 300 g / 10 min and the MFI at 190 ⁰ C and a load of 2.16 kg is measured.

The present invention further relates to the use of the SMC release films as release films for semifinished products of liquid glass resin impregnated fiberglass mats.

The content of copolymer in the molding composition can be from 1 to 90% by weight, based on the weight of the overall molding composition. Preference is given to 2 to 50 wt .-%, particularly preferably 5 to 20 wt .-% of copolymer wherein the molding composition contains 10 to 99 wt .-% polyamide or polyester.

However, the invention also relates to the use of molding compositions containing

A) 10 to 99 wt .-% polyamide or polyester and

B) 1 to 90 wt .-%, preferably 2 to 50 wt .-%, particularly preferably 5 to 20 wt .-% of a copolymer of at least one olefin, preferably α-olefin and at least one acrylic acid ester of an aliphatic alcohol wherein the MFI ( Melt Flow Index) of the copolymer B) is greater than 300 g / 10 min and the MFI at 190 ⁰ C and a load of 2.16 kg is determined or measured, for the production of SMC release films.

As component A), the thermoplastic molding compositions according to the invention comprise at least one thermoplastic polyamide. Particularly preferred are both polyamide 6 and polyamide - -

66 with relative solution viscosities in m-cresol of 2.0 to 4.0, more preferably polyamide 6 with a relative solution viscosity in m-cresol of 2.3 to 3.2. It is also possible to use blends of polyamide 6, polyamide 66, polyamide 46, polyamide 12 or copolyamides. In addition, the thermoplastic molding compositions according to the invention may also contain blends of the described polyamides and other thermoplastic polymers such as polyphenylene oxide, polyethylene or polypropylene.

The polyamides contained in the thermoplastic molding compositions according to the invention can be prepared by various processes and synthesized from different building blocks. For the preparation of polyamides, a variety of procedures are known, depending on the desired end product different monomer units, various chain regulators are used to set a desired molecular weight or monomers with reactive groups for later intended aftertreatments.

The industrially relevant processes for the preparation of polyamides preferably to be used according to the invention are usually via the polycondensation in the melt. In this context, the hydrolytic polymerization of lactams is understood as a polycondensation.

Preferred polyamides according to the invention are partially crystalline polyamides which can be prepared starting from diamines and dicarboxylic acids and / or lactams with at least 5 ring members or corresponding aminocarboxylic acids. Suitable starting materials are aliphatic and / or aromatic dicarboxylic acids, particularly preferably adipic acid, 2,2,4-trimethyladipic acid, 2,4,4-trimethyladipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid, aliphatic and / or aromatic diamines, particularly preferably tetramethylenediamine, Hexamethylenediamine, 1,9-nonanediamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine, the isomers diaminodicyclohexylmethane, diaminodicyclohexylpropanes, bis-aminomethyl-cyclohexane, phenylenediamines, xylylenediamines, aminocarboxylic acids, in particular aminocaproic acid, or the corresponding lactams into consideration. Copolyamides of several of the monomers mentioned are included.

Particularly preferred are caprolactams, most preferably ε-caprolactam is used.

According to the invention, most particularly particularly preferred compounds are PA6, PA66 and other compounds based on aliphatic or / and aromatic polyamides or copolyamides, in which 3 to 11 methylene groups are present on a polyamide group in the polymer chain. - -

The thermoplastic polymers to be used according to the invention in a further preferred embodiment as thermoplastic or component A) are selected from the group of polyesters, preferably polyalkylene terephthalates, particularly preferably polybutylene terephthalates and polyethylene terephthalates, very particularly preferably polybutylene terephthalate.

Preferred polyalkylene terephthalates can be prepared from terephthalic acid (or its reactive derivatives) and aliphatic or cycloaliphatic diols having 2 to 10 carbon atoms by known methods (Kunststoff-Handbuch, Vol. VIII, p. 695 ff, Karl Hanser Verlag, Munich 1973).

Preferred polyalkylene terephthalates contain at least 80 mol%, preferably 90 mol%, based on the dicarboxylic acid, terephthalic acid residues and at least 80 mol%, preferably at least 90 mol%, based on the diol component, ethylene glycol and / or 1,3-propanediol - and / or butanediol-l, 4-radicals.

In addition to terephthalic acid residues, the preferred polyalkylene terephthalates may contain up to 20 mol% of radicals of other aromatic dicarboxylic acids having 8 to 14 carbon atoms or aliphatic dicarboxylic acid radicals having 4 to 12 carbon atoms, in particular radicals of phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid , 4,4'-diphenyldicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, cyclohexanediacetic acid, cyclohexanedicarboxylic acid.

The preferred polyalkylene terephthalates, in addition to ethylene or 1,3-propanediol or 4,9-butanediol, up to 20 Mo 1% of other aliphatic diols having 3 to 12 carbon atoms or cycloaliphatic diols having 6 to 21 carbon atoms. Contain atoms, in particular radicals of 1,3-propanediol, 2-ethylpropanediol-1,3-neopentyl glycol, pentanediol-1,5, hexanediol-1,6, cyclohexane-dimethanol-1,4,3-methylpentanediol-2,4, 2-methylpentanediol-2,4, 2,2,4-trimethylpentanediol-1,3 and -1,6,2-ethylhexanediol-1,3-2,2-diethylpropanediol-1,3-hexanediol-2,5, l, 4-di (β-hydroxyethoxy) benzene, 2,2-bis (4-hydroxycyclohexyl) propane, 2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane, 2,2-bis- (3-.beta.-hydroxyethoxyphenyl) -propane and 2,2-bis (4-hydroxypropoxyphenyl) -propane.

Particularly preferred are polyalkylene terephthalates which are prepared solely from terephthalic acid and its reactive derivatives, in particular their dialkyl esters, and ethylene glycol and / or 1,3-propanediol and / or 1,4-butanediol. Particular preference is given to using polyethylene and polybutylene terephthalate or mixtures of these polyalkylene terephthalates.

Preferred polyalkylene terephthalates are also copolyesters which consist of at least two of the abovementioned acid components and / or of at least two of the abovementioned Alcohol components are prepared, particularly preferred copolyesters s P o Iy- (ethylene glycol / butanediol-1, 4) terephthalates.

The polyalkylene terephthalates generally have an intrinsic viscosity of about 0.3 cffiVg to 1.5 cm / g, preferably 0.4 cm / g to 1.3 cm / g, more preferably 0.5 cm / g to 1.0 cm / g each measured in phenol / o-dichlorobenzene (1: 1 parts by wt.) at 25 ° C.

The thermoplastic polyesters to be used according to the invention can also be used in a mixture with other polyesters and / or further polymers.

As component B), the molding compositions to be used according to the invention comprise random copolymers of at least one olefin, preferably α-olefin and at least one acrylic ester of an aliphatic alcohol, the MFI of the copolymer B) being greater than 300 g / 10 min. In a preferred embodiment, the copolymer B) to less than 4 wt .-%, more preferably less than 1.5 wt .-% and most preferably to 0 wt .-% of monomer units, the other reactive functional groups selected from the group comprising epoxides, oxetanes, anhydrides, imides, aziridines, furans, acids, amines, oxazolines.

Suitable olefins, preferably α-olefins, as a constituent of the copolymers B) preferably have between 2 and 10 carbon atoms and may be unsubstituted or substituted by one or more aliphatic, cycloaliphatic or aromatic groups.

Preferred olefins are selected from the group comprising ethene, propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-pentene. Particularly preferred olefins are ethene and propene, most preferably ethene.

Also suitable are mixtures of the olefins described.

In a further preferred embodiment, the further reactive functional groups of the copolymer B), selected from the group comprising epoxides, oxetanes, anhydrides, imides, aziridines, furans, acids, amines, oxazolines, are introduced exclusively via the olefins into the copolymer B).

The content of the olefin in the copolymer B) is between 50 and 90 wt .-%, preferably between 55 and 75 wt .-%.

The copolymer B) is further defined by the second component besides the olefin. The second constituent used are alkyl esters or arylalkyl esters of acrylic acid, the alkyl - - or arylalkyl group of 1-30 carbon atoms is formed. The alkyl or arylalkyl group may be linear or branched and may contain cycloaliphatic or aromatic groups, but may also be substituted by one or more ether or thioether functions. Suitable acrylic esters in this context are also those synthesized from an alcohol component based on oligoethylene glycol or oligopropylene glycol having only one hydroxyl group and at most 30 carbon atoms.

The alkyl group or arylalkyl group of the acrylic ester may preferably be selected from the group comprising methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-pentyl, 1-hexyl, 2-hexyl, 3-hexyl, 1-heptyl, 3-heptyl, 1-octyl, 1- (2-ethyl) -hexyl, 1-nonyl, 1-decyl, 1-dodecyl, 1-lauryl or 1-octadecyl. Preferred are alkyl groups or arylalkyl groups having 6-20 carbon atoms. Branched alkyl groups are particularly preferred which lead to a lower glass transition temperature T _G compared to linear alkyl groups of the same number of carbon atoms.

Particular preference according to the invention is given to copolymers B) in which the olefin is copolymerized with 2-ethylhexyl acrylate. Also suitable are mixtures of the described acrylic acid esters.

Preferred here is the use of more than 60 wt .-%, more preferably more than 90 wt .-% and most preferably the use of 100 wt .-% of acrylic acid (2-ethyl) - hexyl ester based on the total amount of acrylic acid ester in the copolymer B).

In a further preferred embodiment, the further reactive functional groups selected from the group comprising epoxides, oxetanes, anhydrides, imides, aziridines, furans, acids, amines, oxazolines of the copolymer B) are introduced exclusively into the copolymer B) via the acrylic esters.

The content of the acrylic acid ester in the copolymer B) is between 10 and 50 wt .-%, preferably between 25 and 45 wt .-%.

Suitable copolymers B) are characterized in addition to the composition by the low molecular weight. Accordingly, copolymers B) capable of handling the MFI value (melt flow index) measured at 190 ⁰ C and a load of 2.16 kg, of greater than 300 g / 10 min are include for the inventive molding compositions. Preferred copolymers have an MFI of between 300 and 900 g / 10 min, more preferably between 400 and 800 g / 10 min, particularly preferably between 500 and 750 g / 10 min. Particularly preferred copolymers as component B) are selected from the group of the materials offered by the company Arkema under the brand name Lotryl EH, which are usually used as hot melt adhesive. The corresponding product under the trade name Lotryl ^® 37 EH 550 is particularly preferred.

In a preferred embodiment, the molding compositions according to the invention in addition to the components A), B)

C) 0.01 to 10.0 wt.%, Preferably 0.1 to 5.0 wt.% Further additives.

Further additives of component C) are preferably stabilizers, more preferably UV stabilizers, heat stabilizers, gamma ray stabilizers, hydrolysis stabilizers, and

Antistatic agents, emulsifiers, nucleating agents, plasticizers, processing aids,

Impact modifiers, lubricants, mold release agents, antiblocking additives, dyes or

Pigments. The above-mentioned and other suitable additives are described, for example, in Plastics

Additives Handbook, 5th Edition, Hanser Verlag, Munich, 2001, pages 80-84, 546-547, 688, 872-874, 938, 966. The additives can be used alone or in admixture or in the form of masterbatches.

Stabilizers which are preferred according to the invention are sterically hindered phenols and / or phosphites, hydroquinones, aromatic secondary amines such as diphenylamines, substituted resorcinols, salicylates, benzotriazoles and benzophenones, as well as variously substituted representatives of these groups and / or mixtures thereof.

As UV stabilizers, various substituted resorcinols, salicylates, benzotriazoles or benzophenones are preferably used.

In the case of impact modifiers (elastomer modifiers) are generally copolymers which are preferably composed of at least two of the following monomers: ethylene, propylene, butadiene, isobutene, isoprene, chloroprene, vinyl acetate, styrene, acrylonitrile and acrylic or methacrylic acid esters with 1 to 18 C atoms in the alcohol component. The copolymers may contain compatibilizing groups, e.g. Maleic anhydride or epoxide.

Dyes or pigments which are preferred according to the invention can be inorganic pigments, particularly preferably titanium dioxide, ultramarine blue, iron oxide, zinc sulfide or carbon black, and organic compounds - -

Pigments, more preferably phthalocyanines, quinacridones, perylenes and dyes such as nigrosine and anthraquinones as colorants and other colorants.

Nucleating agents which are preferred according to the invention are sodium or calcium phenylphosphinate, aluminum oxide or silicon dioxide or talc, particularly preferably talc.

Inventively preferred sliding and / or mold release agents are long-chain fatty acids (eg stearic acid), their salts (eg Ca or Zn stearate) and their ester derivatives or amide derivatives (eg ethylene-bis-stearylamide), montan waxes (eg esters of montan acids with ethylene glycol) and low molecular weight polyethylene or polypropylene waxes. Inventively particularly preferred lubricants and / or mold release agents are from the group of esters or amides of saturated or unsaturated aliphatic carboxylic acids having 8 to 40 carbon atoms with aliphatic saturated alcohols or amines having 2 to 40 carbon atoms.

Antiblocking additives which are preferred according to the invention are silica, other finely divided mineral powders or waxes.

The invention further relates to the use of olefin-acrylate copolymers for the production of films based on thermoplastic molding compositions of polyamide or polyester having improved chemical resistance to liquid casting resin impregnated glass fiber mats, characterized in that the copolymers measured a MFI value (MeIt Flow Index) at 190 ⁰ C and a load of 2.16 kg of greater than 300 g / 10 min.

In a preferred embodiment, it is films based on polyamide particularly preferably polyamide 6, polyamide 66 or polyester, preferably polybutylene terephthalate and olefin-acrylate copolymer.

The invention further relates to the use of olefin-acrylate copolymers having a MFI value (MeIt Flow Index) measured at 190 ⁰ C and a load of 2.16 kg of greater than 300 g / 10 min, for the production of SMC release films on Basis thermoplastic molding compounds with polyamide or polyester.

In a preferred embodiment, the present invention relates to the use of SMC release films having improved chemical resistance to liquid casting resin impregnated glass fiber mats for covering styrene-containing casting resins or cast resin products.

In a further preferred embodiment, the present invention relates to improving the chemical resistance of SMC release films to liquid cast resin impregnated glass fiber mats, wherein the liquid component is styrene. - -

The molding compositions to be used according to the invention are prepared by known processes by mixing the components in the polymer melt. The mixing of the components takes place in the corresponding proportions by weight. Preferably, the mixing (compounding) of the components at temperatures of 220 to 360 ⁰ C by mixing together, mixing, kneading, extruding or rolling of the components, more preferably by compounding on a co-rotating twin-screw extruder or Buss kneader. It may be advantageous to premix individual components. It may also be advantageous, moldings or films made of a room temperature (preferably 0 to 40 ⁰ C) physical mixture (dry blend) to prepare pre-mixed components and / or individual components directly. The molding compositions prepared as described can be processed by extrusion, blow molding or injection molding.

The films to be produced according to the invention from the molding compositions can serve, for example, as release films for external covering or packaging of semifinished products of glass fiber mats impregnated with liquid casting resin or other unfinished cured resin products, as a lining for molds, molds, work surfaces and tools for processing styrene containing casting resins with or without glass fibers in the production of hollow bodies in shipbuilding, liquid tanks, corrugated sheets or prefabricated synthetic resin blocks for milling shaping, as well as aids in the transport, storage or processing of casting resins in the manufacture of household items, vessels, decorative moldings, buttons, handles, Knobs or in the processing of casting resins for embedding objects for illustrative purposes or for the preparation of microscopic photographs and other handling of casting resins.

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Examples

To demonstrate the improvements according to the invention, appropriate plastic molding compounds were first prepared by compounding. The individual components were mixed in a twin-screw extruder of the type ZSK 32 Compounder from Coperion Werner & Pfleiderer (Stuttgart, Germany) at temperatures between 260 and 290 ⁰ C, discharged as a strand in a water bath, cooled to Granulierfähigkeit and granulated. After drying (usually two days at 70 ⁰ C in a vacuum oven), the processing of the granules was carried out on a film extrusion line to monolayer films of 50 microns thickness. The resistance of the resulting films to styrene was determined by measuring the styrene permeability. To this end, pieces of the film to be checked were tightly fastened in the 4000 mm ² wall cutout of an otherwise tightly closable 50 ml metal vessel. The vessel was filled with styrene (stabilized with tert-butyl pyrocatechol) so high that the foil piece in the cut-out window of the vessel wall was completely covered by the liquid. The vessel was sealed and weighed for 48 hours to determine the amount of styrene pushed out through the film. The weight loss of the entire experimental arrangement relative to the initial weight served as a measure of the permeation of styrene through the release film in the wall section of the metal vessel.

The following compositions were processed and tested as described above.

Table 1: Embodiments of the molding compositions of the invention

The following table shows the amounts of starting materials in% by weight.

Examples 1 and 2 show that the styrene permeability of release films with polyamide or polyester content resulted from the improved chemical resistance and thus lower - -

Pore formation is significantly lower than in a conventional, purely polyethylene-based release film.

used material

Thermoplastic, e.g. Polyamide 6, linear, with a relative solution viscosity of a 1% solution in m-cresol of 3.9 or polybutylene terephthalate from Lanxess Deutschland GmbH

Ethylene-acrylate copolymer, e.g. Lotryl 37 EH 550 from Arkema S.A.

Claims

- Patent claims 1. SMC release films based on thermoplastic molding compositions of polyamides or polyesters, characterized in that the thermoplastic molding compositions contain at least one random copolymer of at least one olefin, preferably α-olefin and at least one acrylic acid ester of an aliphatic alcohol, wherein the MFI (MeIt Flow Index) of the copolymer B) is greater than 300 g / 10 min and the MFI at 190 ⁰ C and a load of 2.16 kg is measured. 2. SMC release films according to claim 1, characterized in that is used as the polyamide polyamide 6 or polyamide 66 or as polyester polybutylene terephthalate. 3. SMC release films according to claims 1 or 2, characterized in that the Polyamide 6 or polyamide 66 has a relative solution viscosity in m-cresol of 2.0 to 4.0. 4. SMC release films according to claims 1 to 3, characterized in that as olefin α- Olefme be used. 5. SMC release films according to claim 4, characterized in that the α-olefin between Has 2 and 10 carbon atoms and may be unsubstituted or substituted with one or more aliphatic, cycloaliphatic or aromatic groups. 6 .. SMC release films according to claims 1 to 5, characterized in that the copolymer B) consists of less than 4 wt .-% of monomer units, the further reactive functional groups selected from the group comprising epoxides, oxetanes, Anhydrides, imides, aziridines, furans, acids, amines, oxazolines. 7. SMC release films according to claims 1 to 6, characterized in that as a further Component used in the copolymer B) alkyl esters or arylalkyl esters of acrylic acid, the alkyl or arylalkyl group of 1-30 carbon atoms is formed. 8. Use of molding compositions containing A) 10 to 99 wt .-% polyamide or polyester and B) 1 to 90 wt .-%, preferably 2 to 50 wt .-%, particularly preferably 5 to 20 wt .-% of a random copolymer of at least one olefin and at least one acrylic acid ester of an aliphatic alcohol, wherein - - The MFI of the copolymer B) is greater than 300 g / 10 min and the MFI at 190 ⁰ C and a load of 2.16 kg is determined or measured, for the production of SMC release films. 9. Use according to claim 8, characterized in that the molding compositions in addition to A) and B) contain C) further additives. 10. Use according to claim 9, characterized in that as additives UV stabilizers, heat stabilizers, gamma ray stabilizers, hydrolysis stabilizers, antistatic agents, emulsifiers, nucleating agents, plasticizers, processing aids, impact modifiers, lubricants, mold release agents, antiblocking agents, dyes and pigments, alone or in Mixture or in the form of masterbatches are used. 11. Use of olefin-acrylate copolymers having a MFI value (MeIt Flow Index) measured at 190 ⁰ C and a load of 2.16 kg of greater than 300 g / 10 min, for the production of SMC release films based on thermoplastic molding compositions made of polyamide or polyester. 12. Use according to claim 11, characterized in that the SMC release films with improved chemical resistance to liquid casting resin impregnated glass fiber mats are used to cover styrene-containing casting resins or cast resin products. 13. Use according to claim 12, characterized in that the resistance of SMC release films to styrene is improved.