EP1789478A1

EP1789478A1 - Inorganically coated synthetic body, method for producing the same and its use

Info

Publication number: EP1789478A1
Application number: EP05768188A
Authority: EP
Inventors: Patrick Becker; Rolf Neeb; Ghirmay Seyoum
Original assignee: Roehm GmbH Darmstadt
Current assignee: Roehm GmbH Darmstadt
Priority date: 2004-09-16
Filing date: 2005-07-09
Publication date: 2007-05-30
Also published as: KR20070064597A; DE102004045295A1; WO2006029667A1; ZA200702186B; MX2007002889A; CN1993407A; US20080032124A1; TW200619284A

Abstract

The invention relates to a method for producing a synthetic body from a synthetic material, obtained by radical polymerization, which is coated on one or several sides with an Si-containing or inorganic substance. According to the inventive method, a substrate is coated with a lacquer composition which contains inorganic particles dissolved in a solvent which may optionally also contain a flow-control agent. One or more substrates that are coated in this manner can be used to construct a polymerization chamber, the coated sides facing the interior of the chamber. After radical polymerization of a monomer mixture in the presence of a polymerization initiator and a separating agent mixture the inward inorganic coating is transferred from the substrate to or onto the surfaces of the radically polymerized synthetic material or the corresponding synthetic body. The invention also relates to the corresponding synthetic bodies and their uses and to the use of the separating agent mixture in the polymerization casting method.

Description

Plastic body with inorganic coating, method of manufacture and uses

The invention relates to plastic bodies with inorganic coating and process for their preparation and their use.

State of the art

EP-A-0 193 269 relates to substrates coated with silica particles. The coating is very uniform with respect to the layer thickness, adheres extremely firmly to the substrate and has good antireflective properties.

US Pat. No. 4,571,361 describes antistatic plastic films. This slides from z. As cellulose acetate or polyethylene terephthalate with polymerizable coating systems, the z. As antimony tin oxide particles may contain coated. This gives films with abrasion-resistant coatings and low surface resistances in the range less than or equal to 10 ⁷ Ω.

EP-B 0 447 603 describes antistatic coating compositions comprising a silicate solution and a conductive solution. Both solutions are mixed to hydrolyze and polycondensate to said coating compositions, which has a chemical bond between the silicate and the conductive material. The coating compositions are suitable for the production of antistatic, non-dazzling anti-glare screens made of glass or plastic panels. The addition of release agents to polymerizable liquids which are polymerized in the Kammerpolymerisationsverfahren is known. US 5,134,210 very generically names a variety of suitable substances, in particular dioctylsulfosuccinate to give acceptable results.

Task and solution

It is known, substrates such. As glass or plastic body with inorganic layers, the z. B. may have antistatic properties to provide. As a rule, the coatings are applied to the substrate surface by means of coating systems which can be cured by drying or polymerization. Coated substrates are obtained with quite satisfactory properties in terms of abrasion resistance and z. B. electrical conductivity.

It was seen as an object to provide a method which makes it possible to provide plastic body with inorganic coatings, with an improved compared to the prior art connection to the plastic surface is to be achieved. In particular, the method according to the invention should be easy to carry out and be applicable in production with the lowest possible scrap.

The task is solved by a

Process for the production of a plastic body from a plastic obtainable by free-radical polymerization with one-sided or multi-sided inorganic coating by the process steps

a) coating of a substrate by means of knife coating, flooding or dipping with a coating composition comprising a silicon-based adhesion promoter and inorganic particles in a weight ratio of 1: 9 to 9: 1 in a solvent, which may optionally contain additional flow control agents, b) C) using one or more such coated substrates for construction, a polymerization chamber, wherein the coated sides are inside the chamber, d) filling a polymerizable liquid of radically polymerizable monomers optionally with polymer fraction into the polymerization chamber, the polymerizable liquid containing 0.16 to 0.28% by weight of a release agent mixture of a Cβ - C ₂₀ alkyl sulfosuccinate and a Cβ - C ₂ 0 alkyl phosphate, e) free radical polymerization of the polymerizable fluid in the presence of a polymerization initiator, wherein the internal inorganic coating passes from the substrate into or onto the surfaces of the free-radically polymerized plastic or of the plastic body, and f) removal of the coated plastic body with one-sided or multi-sided inorganic coating from the polymerization chamber. By means of the method according to the invention, it is possible to obtain plastic bodies having improved properties with respect to the abrasion resistance of the surface. Furthermore, very uniform layer thicknesses of the inorganic coatings and a high uniformity of the surfaces can be achieved. The plastic body can also be easily removed from the polymerization, so that the process can be operated as a whole uncritically and in large series largely without interference.

Embodiment of the invention

The invention relates to a

Process for the production of a plastic body from a plastic obtainable by free-radical polymerization with one-sided or multi-sided inorganic coating.

A plastic body is to be understood as meaning any plastic object in virtually any shape which is accessible in the course of the method according to the invention. Preferred plastic body can, for. B. have the shape of flat plates. However, other plastic bodies such as corrugated sheets, cubes, cuboids, round bars, etc. are conceivable. The plastic body can, for. B. have an E-modulus according to ISO 527-2 of at least 1500 MPa, preferably at least 2000 MPa. Plates can with z. B. have a thickness in the range of 1 mm to 200 mm, in particular 3 to 30 mm. Typical dimensions, for example, for solid panels are in the range of 3 × 500 to 2000 × 2000 to 6000 mm (thickness × width × length). The inorganic coating can be single or multi-sided depending on the application. For flat plates, it will be preferable to coat one or both of the large areas. However, it is also possible to coat the smaller edge surfaces or make an all-round coating of all surfaces.

The method comprises at least the method steps a) to f)

Process step a):

Coating of a substrate by means of knife coating, flooding or dipping with a coating composition comprising a silicon-based adhesion promoter and inorganic particles in a weight ratio of 1: 9 to 9: 1 in a solvent, which may optionally additionally contain flow control agents,

Under a substrate is initially a virtually arbitrary object in terms of shape and material to understand, if this is suitable for the purposes of the invention. In particular, the substrate must be coatable and suitable for the construction of a polymerization chamber. For this purpose, in particular flat plates made of a hard, solid material such. As ceramic, metal or more preferably glass. Sheets of plastic or plastic films may also be suitable. In particular, plastic films of polyethylene terephthalate may be suitable. Films may be suitable for building a polymerization chamber on a hard substrate, e.g. B be placed on a glass plate, glued or mounted. The substrate may be made of a plastic. These include in particular polycarbonates, polystyrenes, polyesters, for example polyethylene terephthalate (PET), which may also be modified with glycol, and polybutylene terephthalate (PBT), cycloolefinic copolymers (COC), acrylonitrile / butadiene / styrene copolymers and / or poly (meth) acrylates ,

Polycarbonates, cycloolefinic polymers and poly (meth) acrylates are preferred, with poly (meth) acrylates being particularly preferred.

Polycarbonates are known in the art. Polycarbonates can be formally considered as polyesters of carbonic acid and aliphatic or aromatic dihydroxy compounds. They are readily accessible by reaction of diglycols or bisphenols with phosgene or carbonic acid diesters by polycondensation or transesterification reactions.

Here, polycarbonates are preferred which are derived from bisphenols. These bisphenols include, in particular, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4-hydroxyphenyl) butane (bisphenol B), 1,1-bis (4-hydroxyphenyl ) cyclohexane (bisphenol C), 2,2'-methylenediphenol (bisphenol F), 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane (tetrabromobisphenol A) and 2,2-bis (3,5-bis) dimethyl-4-hydroxyphenyl) propane (tetramethyl bisphenol A).

Typically, such aromatic polycarbonates are prepared by interfacial polycondensation or transesterification, details of which are set forth in Encycl. Polym. Be. Engng. 11, 648-718 are shown.

In the interfacial polycondensation, the bisphenols are emulsified as an aqueous alkaline solution in inert organic solvents such as methylene chloride, chlorobenzene or tetrahydrofuran, and in one Step reaction reacted with phosgene. Amines are used as catalysts, and in the case of sterically hindered bisphenols also phase transfer catalysts are used. The resulting polymers are soluble in the organic solvents used.

The choice of bisphenols allows the properties of the polymers to be varied widely. With simultaneous use of different bisphenols, block polymers can also be built up in multistage polycondensations.

Cycloolefinic polymers are polymers obtainable using cyclic olefins, especially polycyclic olefins.

Cyclic olefins include, for example, monocyclic olefins, such as cyclopentene, cyclopentadiene, cyclohexene, cycloheptene, cyclooctene and alkyl derivatives of these monocyclic olefins having 1 to 3 carbon atoms, such as methyl, ethyl or propyl, such as methylcyclohexene or dimethylcyclohexene, and acrylate and / or methacrylate derivatives of these monocyclic Links. In addition, cycloalkanes having olefinic side chains can also be used as cyclic olefins, such as cyclopentyl methacrylate.

Preference is given to bridged, polycyclic olefin compounds. These polycyclic olefin compounds may have the double bond both in the ring, which are bridged polycyclic cycloalkenes, as well as in side chains. These are vinyl derivatives, allyloxycarboxy derivatives and (meth) acryloxy derivatives of polycyclic cycloalkane compounds. These compounds may further include alkyl, aryl or aralkyl substituents. Illustrative polycyclic compounds include, but are not limited to, bicyclo [2.2.1] hept-2-ene (norbornene), bicyclo [2.2.1] hept-2,5-diene (2,5-norbornadiene), ethyl -bicyclo [2.2.1] hept-2-ene (ethylnorbomene), ethylidenebicyclo [2.2.1] hept-2-ene (ethylidene-2-norbornene), phenylbicyclo [2.2.1] hept-2-ene, bicyclo [4.3 .0] nona-3,8-diene, tricyclo [4.3.0.1 ² ' ⁵ ] - 3-decene, tricyclo [4.3.0.1 ²ⁱ⁵ ] -3,8-decene- (3,8-dihydro-dicyclopentadiene), tricyclo [4.4 .0.1 ^{2> 5} ] -3-undecene, tetracyclo [4.4.0.1 ² ' ⁵ , 1 ⁷ ' ¹⁰ ] -3-dodecene, ethylidenetetracyclo [4.4.0.1 ²ⁱ⁵ .1 ⁷ⁱ¹⁰ ] -3-dodecene,

Methyloxycarbonyltetracyclo [4.4.0.1 ²ⁱ⁵ , ¹⁷ⁱ¹⁰ ] -3-dodecene, ethylidene-9-ethyltetracyclo [4.4.0.1 ² ' ⁵ , 1 ⁷ - ¹⁰ ] -3-dodecene, pentacyclo [4.7.0.1 ² ' ⁵ , O, O ³ ^'13 , 1 ⁹ ' ¹² ] -3- pentadecene, pentacyclo [6.1.1 ^{3> 6} .0 ²ⁱ⁷ .0 ⁹ ^'13 ] -4-pentadecene, hexacyclo [6.6.1.1 ³ - ⁶ .1 ¹⁰ⁱ¹³ .0 ²ⁱ⁷ .0 ⁹ⁱ¹⁴ ] -4-heptadecene, dimethylhexacyclo [6.6.1.1 ³ - ⁶ .1 ¹⁰ ^'13 .0 ² ' ⁷ .0 ⁹ ^'14 ] -4-heptadecene, bis (allyloxycarboxy) tricyclo [4.3.0.1 ² ' ⁵ ] decane,

Bis (methacryloxy) tricyclo [4.3.0.1 ²ⁱ⁵ ] decane, bis (acryloxy) tricyclo [4.3.0.1 ² - ⁵ ] decane.

The cycloolefinic polymers are prepared using at least one of the cycloolefinic compounds described above, in particular the polycyclic hydrocarbon compounds. In addition, in the preparation of the cycloolefinic polymers further olefins can be used which can be copolymerized with the aforementioned cycloolefinic monomers. These include u.a. Ethylene, propylene, isoprene, butadiene, methyl pentene, styrene and vinyl toluene.

Most of the aforementioned olefins, especially the cycloolefins and polycycloolefins, can be obtained commercially. In addition, many cyclic and polycyclic olefins are available through Diels-Alder addition reactions. The preparation of the cycloolefinic polymers can be carried out in a known manner, as described, inter alia, in Japanese Patent Nos. 11818/1972, 43412/1983, 1442/1986 and 19761/1987 and Japanese Patent Laid-Open Nos. 75700/1975, 129434/1980, 127728 / 1983, 168708/1985, 271308/1986, 221118/1988 and 180976/1990 and in the European patent applications EP-AO 610 851, EP-AO 485 893, EP-AO 407 870 and EP-A-0 688 801.

The cycloolefinic polymers can be polymerized in a solvent using, for example, aluminum compounds, vanadium compounds, tungsten compounds or boron compounds as a catalyst.

It is assumed that the polymerization can be carried out under ring opening or under opening of the double bond, depending on the conditions, in particular the catalyst used.

In addition, it is possible to obtain cycloolefinic polymers by radical polymerization using light or an initiator as a radical generator. This applies in particular to the acryloyl derivatives of cycloolefins and / or cycloalkanes. This type of polymerization can be carried out both in solution and in substance.

Another preferred plastic substrate comprises poly (meth) acrylates. These polymers are generally obtained by radical polymerization of mixtures containing (meth) acrylates. These have been set out above, and depending on the preparation, both monofunctional and polyfunctional (meth) acrylates can be used.

According to a preferred aspect of the present invention, these mixtures contain at least 40% by weight, preferably at least 60% by weight and particularly preferably at least 80% by weight, based on the weight of the monomers, of methyl methacrylate.

In addition to the (meth) acrylates set out above, the compositions to be polymerized may also contain other unsaturated monomers which are copolymerizable with methyl methacrylate and the abovementioned (meth) acrylates. Examples of this were explained in more detail in particular under component E).

In general, these comonomers are used in an amount of 0 to 60 wt .-%, preferably 0 to 40 wt .-% and particularly preferably 0 to 20 wt .-%, based on the weight of the monomers, wherein the compounds individually or can be used as a mixture.

The polymerization is generally started with known free-radical initiators, which are described in particular under component D). These compounds are often used in an amount of 0.01 to 3 wt .-%, preferably from 0.05 to 1 wt .-%, based on the weight of the monomers.

The aforementioned polymers may be used singly or as a mixture. It is also possible to use various polycarbonates, poly (meth) acrylates or cycloolefinic polymers which differ, for example, in molecular weight or in the monomer composition.

Furthermore, the plastic substrates can be produced by Gußkammerverfahren. Here, for example, suitable (meth) acrylic mixtures are added in a mold and polymerized. Such (meth) acrylic mixtures generally have the above-described (meth) acrylates, in particular methyl methacrylate. In addition, the (meth) acrylic mixtures may contain the copolymers described above, and in particular for adjusting the viscosity, polymers, in particular poly (meth) acrylates.

The weight average molecular weight M _{w of} the polymers prepared by cast-chamber processes is generally higher than the molecular weight of polymers used in molding compositions. This results in a number of known advantages. In general, the weight-average molecular weight of polymers prepared by cast-chamber processes is in the range of 500,000 to 10,000,000 g / mol, without limitation.

Preferred plastic substrates produced by the casting chamber method can be obtained commercially from Cyro Inc. USA under the trade name ®Acrylite.

In addition, the substrates may contain conventional additives of all kinds, if they are made of plastic. These include, inter alia, antioxidants, mold release agents, flame retardants, lubricants, dyes, flow improvers, fillers, light stabilizers and organic phosphorus compounds such as phosphoric acid esters, phosphoric acid diesters and phosphoric acid monoesters, phosphites, phosphorinanes, phospholanes or phosphonates, pigments, weathering agents and plasticizers. However, the amount of additives is limited to the purpose of use.

Particularly preferred molding compositions which comprise poly (meth) acrylates are commercially available under the trade name ®Acrylite from the company Cyro Inc. USA. Preferred molding compositions comprising cycloolefinic polymers may be sold under the tradename ®Topas of Ticona and © Zeonex of Nippon Zeon. Polycarbonate molding compositions are available, for example, under the trade name ®Makrolon from Bayer or ®Lexan from General Electric.

The plastic substrate particularly preferably comprises at least 80% by weight, in particular at least 90% by weight, based on the total weight of the substrate, of poly (meth) acrylates, polycarbonates and / or cycloolefinic polymers. Particularly preferably, the plastic substrates are made of polymethyl methacrylate, wherein the polymethyl methacrylate may contain conventional additives.

According to a preferred embodiment, plastic substrates may have an oil absorption coefficient ≥ 1 ISSOO 117799 // 1 of at least 10 kJ / m ² , preferably at least 15 kJ / m ² .

The shape and size of the plastic substrate are not essential to the present invention. In general, plate or tabular substrates are often used which have a thickness in the range of 1 mm to 200 mm, in particular 5 to 30 mm.

The paint composition contains a coupling agent and inorganic particles in a weight ratio of 1 to 9 to 9 to 1.

The adhesion promoter may consist of colloidally dissolved SiO 2 particles or of silane condensates. Preference is given to 1 -2 wt .-% S1O ₂ and 2.5 to 7.5 wt .-% of further inorganic particles in a solvent or solvent mixture, which optionally contain additional flow aid and water. The flow aid can z. B. in a concentration of 0.01 to 2, preferably 0.1 to 1 wt .-%. Other binders or polymerizing organic components are preferably not or if at all contained only in small, non-critical amounts.

In the context of the present invention, the term inorganic means that the carbon content of the inorganic coating is at most 25% by weight, preferably at most 17% by weight and most preferably at most 10% by weight, based on the weight of the inorganic coating (a ). This size can be determined by elemental analysis.

According to a further aspect of the present invention, it is also possible to use silane condensates which contain colloidally dissolved SiO ₂ particles. Such solutions can be obtained by the sol-gel method, wherein in particular tetraalkoxysilanes and / or tetrahalosilanes are condensed.

Conventionally, water-containing coating compositions are prepared from the aforementioned silane compounds by hydrolyzing organosilicon compounds with an amount of water sufficient for hydrolysis, ie> 0.5 mole of water per mole of the groups intended for hydrolysis, such as alkoxy groups, preferably with acid catalysis. As acids, for example, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, etc., or organic acids such as carboxylic acids, organic sulfonic acids, etc., or acidic ion exchangers may be added, wherein the pH of the hydrolysis reaction is usually between 2 and 4.5 , preferably at 3. The coating composition preferably contains inorganic particles in the form of 1 to 2, preferably 1, 2 to 1, 8 wt .-% SiO 2 and 2.5 to 7.5, preferably 3 to 7, particularly preferably 4 to 6 wt .-% antimony Tin oxide particles in water as a solvent. The pH is preferably set to be alkaline so that the particles do not agglomerate. The particle size of these oxide particles is not critical, but the transparency is dependent on the particle size. Preferably, the particles have a size of at most 300 nm, wherein they are in particular in a range of 1 to 200 nm, preferably 1 to 50 nm.

According to a particular aspect of the present invention, the colloidal solution is preferably applied at a pH greater than or equal to 7.5, in particular greater than or equal to 8 and particularly preferably greater than or equal to 9.

Basic colloidal solutions are cheaper than acidic solutions. In addition, basic colloidal solutions of oxide particles are particularly simple and storable for a long time.

The coating compositions described above can be sold commercially under the trade name ®Ludox (Grace, Worms); ® Levasil (Bayer, Leverkusen); © Klebosol, (Clariant).

Preferably, in order to promote a good distribution of the particles, in addition to the mentioned flow aid, for. B. in a concentration of 0.1 to 1, preferably 0.3 to 0.5 wt .-%.

The paint composition may be mixed prior to use of individual components. You can z. B. use a commercially available 10 to 15% antimony tin oxide solution or suspension in water (solution 1) and mix them with a usable silica sol solution (solution 2) and a dilution solution (solution 3).

The silica sol solution can first in concentrated form z. B. SiO ₂ particles in the size range of 10 to 100 nm, preferably 7 to 50 nm and present in the form of a 20 to 30% alkaline, aqueous solution or suspension. The concentrated solution can again be adjusted to about 30% strength in H ₂ O as a ready-to-use solution (solution 2). Preference is given to adding a distribution or a flow aid. Suitable z. As surfactants, preferred is the addition of [fatty alcohol + 3-ethylene oxide, Genapol X 80].

In addition to the flow control agent with anionic groups, the coating composition may comprise further flow control agents, for example nonionic flow control agents. Of these, in particular ethoxylates are preferred, in particular esters and alcohols and phenols can be used with ethoxy groups. These include, inter alia Noπylphenolethoxylate.

The ethoxylates comprise in particular 1 to 20, in particular 2 to 8, ethoxy groups. The hydrophobic radical of the ethoxylated alcohols and esters preferably comprises 1 to 40, preferably 4 to 22, carbon atoms, both linear and branched alcohol and / or ester radicals can be used. Such products can be obtained commercially, for example, under the trade name © Genapol X80.

The addition of nonionic flow control agent is limited to an amount that exhibits substantially no adverse effect on the antistatic coating. In general, the coating composition is admixed with 0.01 to 4% by weight, in particular 0.1 to 2% by weight, of one or more nonionic leveling aids, based on the total weight of the coating composition.

As diluent (solution 3), fully demineralized H ₂ O (deionized water) adjusted to about pH 9.0 with NaOH can be used. Appropriately, a flow aid may also be included here.

Leveling agents having at least one anionic group are known in the art, these leveling agents generally having carboxy, sulfonate and / or sulfate groups. Preferably, these flow control agents comprise at least one sulfonate group. Flow control agents having at least one anionic group include anionic flow control agents and amphoteric flow control agents, which also comprise a cationic group in addition to an anionic group. Of these, anionic flow control agents are preferred. With anionic flow control agents in particular the production of deformable plastic bodies is possible.

Preferably, the flow control agents having at least one anionic group comprise 2 to 20, more preferably 2 to 10 carbon atoms, wherein the organic radical may contain both aliphatic and aromatic groups. According to a particular aspect of the present invention anionic flow control agents are used which comprise an alkyl or a cycloalkyl radical having 2 to 10 carbon atoms.

The flow control agents having at least one anionic group can have further polar groups, for example carboxy, thiocarboxy or imino, carboxylic acid ester, carbonic acid ester, thiocarboxylic acid esters, dithiocarboxylic acid ester thiocarbonic acid ester, dithiocarbonic acid ester and / or dithiocarbonic acid amide groups.

Particularly preferred leveling agents of the formula (I) are used

wherein X is independently an oxygen or a sulfur atom, Y is a group of the formula OR ² , SR ² or NR ² , wherein R ^{2 is} independently an alkyl group of 1 to 5, preferably 1 to 3 carbon atoms and R ^{3 is} an alkylene group of 1 to 10, preferably 2 to 4 carbon atoms and M is a cation, in particular an alkali metal ion, in particular potassium or sodium, or an ammonium ion.

In general, from 0.01 to 1% by weight, in particular from 0.03 to 0.1% by weight, of one or more leveling agents having at least one anionic group, based on the total weight of the coating composition, is added to the coating composition.

Such compounds can be obtained in particular from Raschig AG under the trade name Raschig OPX® or Raschig DPS® and z. B. in a concentration of 0.1 to 1, preferably 0.4 to 0.6 wt .-% may be included. In order to obtain a ready-to-use coating composition, it is preferable to first mix solutions 2 and 3, for example in a ratio of 1: 1 to 1: 2, e.g. B. 1 to 1, 5, and the mixture then with solution 1, in the ratio of about 1 to 1.

Process step b):

Drying the lacquer composition on the substrate to obtain the coated substrate.

After coating a substrate, for. As a glass plate, by knife coating, flooding, dipping the paint composition is dried. This can be z. B. in the temperature range of 50 to 200, preferably from 80 to 120 ⁰ C, wherein the temperature of the temperature resistance of the substrate is to be adjusted. In general, a drying time of 0.1 to 5, preferably 2 to 4 hours is sufficient to obtain a nearly fully cured coating. You can after the dry phase still a stance phase, z. B. 12 to 24 hours at room temperature to ensure complete curing before the coated substrates are reused.

Since the lacquer layer has been formed from a solution which has a solids content of inorganic particles, the layer consists of a continuous three-dimensional network, which is constructed from spherical structures and inevitably has a certain void content. This structure structure is known from EP-A 0 193 269. Process step c):

Use of one or more coated substrates for the construction of a polymerization chamber, wherein coated sides are located in the interior of the chamber.

It is now possible to use one or more of the substrates coated in the preceding process step to build up a polymerization chamber. A polymerization chamber is a sealed space in which a liquid polymerizable mixture can be filled and in which it can be polymerized until a polymerized plastic body is obtained, which can be seen as a solid after opening the chamber. Polymerization chambers are well known z. B. from the production of cast polymethyl methacrylate (see, for example, DE 25 44 245, EP-B 570 782 or EP-A 656 548).

If you have in the previous process step z. As a glass plate coated on one side by flooding, you can now use this, with the coated side inward to build a polymerization chamber, which consists of two spaced apart, plane-parallel glass plates. The other, second glass plate can be a normal, uncoated plate in this case. The distance is ensured by corresponding side parts, or frame. From the production of cast polymethyl methacrylate in particular polymerization chamber of two glass plates with a circumferential elastic cord for sealing are known. The elasticity of the cord serves to compensate for the shrinkage during the polymerization. The chamber is firmly held together by appropriate clips. There are openings for filling and venting. Process step d):

Charging a polymerizable liquid of radically polymerizable monomers, optionally with a polymeric portion, in the polymerization, wherein the polymerizable liquid 0.16 to 0.28 wt .-% of a release agent mixture of a Cβ - C ₂₀ - alkyl sulfosuccinate and a Ce ~ C ₂ o -Alkyl phosphate.

It now fills a polymerizable liquid from radically polymerizable monomers optionally with a polymeric portion in the polymerization. In principle, all liquids which can be polymerized in the chamber process or monomers or monomer / polymer mixtures are suitable. The polymerizable liquid may contain other soluble or insoluble additives such. As pigments, fillers, UV absorbers. It can z. B also impact modifier or light scattering particles of multi-shell constructed and / or crosslinked plastic particles may be included.

Free-radically polymerizable monomers are, for. B. monomers having one or more vinylic group, for. For example, methyl methacrylate, other esters of methacrylic acid, eg. Ethyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, esters of acrylic acid (eg, methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, cyclohexyl acrylate) or styrene and styrene derivatives such as α-methylstyrene or p-methylstyrene. Crosslinking monomers, such as. As triallyl cyanurate, allyl methacrylate or di (meth) acrylates, may also, but preferably only in smaller amounts, for. B. 0.1 to 2 wt .-%, may be included. It may be a homogeneous solution z. B. from 100% methyl methacrylate or a monomer mixture, for. B. predominantly, 80 to 99% by weight of methyl methacrylate and 1 to 20 wt .-% of further copolymerizable monomers such. For example, methyl acrylate. The solution or the monomer mixture may have polymeric components, for example, a mixture of 70 to 95 wt .-% of methyl methacrylate and 5 to 30 wt .-% polymethylmethacrylate be filled.

Release agent mixture

An important aspect of the invention is that the plastic body produced in the polymerization chamber can be easily detached from the previously coated substrates, wherein the electrically conductive coating is transferred to the plastic body. The plastic body should in particular have no turbidity or cracks. During the polymerization, there should be no detachment from the walls of the polymerization chamber and associated deformations. When removing the coated plastic body, the previously coated substrates should not be damaged. Since glass plates are preferably used as coated substrates, glass breakage should be avoided when removing the plastic body. For this reason, according to the claims, a defined release agent mixture is added to the polymerizable liquid. In particular, this measure contributes to a largely trouble-free production process with high throughput rates and a low scrap content.

The polymerizable liquid contains 0.16 to 0.28, preferably 0.18 to 0.25 wt .-% of a release agent mixture of a Cε - C ₂₀ - Alkyl sulfosuccinate, preferably a C ₈ - Cio-alkyl sulfosuccinate and a Ce - C-20-alkyl phosphate, preferably a Cs - Cio-alkyl phosphate. The term C ₆ - C ^ o-alkyl sulfosuccinate and C ₆ - C _2O -AI kylphosphat includes mixtures of the two classes of substances with a.

The proportion of C ₆ - C ₂ o-alkylsulfosuccinate is preferably not more than 0.1, more preferably 0.02 to 0.08 wt .-% in total. The proportion of C ₆ - C ₂ o-alkyl phosphate is preferably not more than 0.2, more preferably 0.12 to 0.18 wt .-% in total.

A suitable C ₆ - C ₂ o-alkylsulfosuccinate is z. B. Diisooctylsulfosuccinat, which may optionally be present as sodium salt, Na Diisooctylsulfosuccinat.

A suitable C ₆ - C20-AI kylphosphat is z. B. (mono) nonyl phosphate or dinonyl phosphate. Particularly preferred is a mixture of (mono) nonyl phosphate or dinonyl phosphate. The proportions of (mono) nonyl phosphate and dinonyl phosphate in the mixture can, for. B. 9 to 1 to 1 to 9, preferably 6 to 4 to 4 to 6.

A release agent mixture of a C ₆ - C ^ o-alkylsulfosuccinate and a C ₆ - C2o-alkyl phosphate in a polymerizable liquid from radically polymerizable monomers, optionally with a polymeric portion, can therefore advantageously for the purpose of improving the replacement of a plastic body produced by the casting process from Polymerization chamber can be used. The use of the release agent mixture in the sense described is therefore not limited to the method according to the invention, although there particularly advantageous use. Process step e):

Radical polymerization of the polymerizable liquid in the presence of a polymerization initiator, wherein the internal inorganic coating from the substrate into or on the surfaces of the radically polymerized plastic or the plastic body passes.

It is the polymerizable solution or the mixture of free-radically pol ymerisi erbaren monomers optionally with a polymeric portion preferably before filling in the polymerization chamber, a polymerization initiator in a uniform distribution. Then you can the polymerizable liquid for plastic z. B. at 40 to 80 ⁰ C polymerize.

Examples of polymerization initiators are: azo compounds such as 2,2'-azobis (isobutyronitrile) or 2.2 ^l -Azobis (2,4-dimethylvaleronitrile), redox systems, such as the combination of tertiary amines with peroxides or preferably peroxides ( See, for example, H. Rauch-Puntigam, Th. Völker, "Acrylic and Methacrylic Compounds", Springer, Heidelberg, 1967 or Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, pp. 386ff, J. Wiley, New York , 1978). Examples of suitable peroxide polymerization initiators are dilauroyl peroxide, tert-butyl peroctoate, tert-butyl perisononanoate, dicyclohexyl peroxydicarbonate, dibenzoyl peroxide or 2,2-bis (tert-butylperoxy) butane. It is also possible to carry out the polymerization preferably with a mixture of different polymerization initiators having a different half-life, for example dilauroyl peroxide and 2,2-bis (tert-butylperoxy) butane, in order to keep the free radical stream constant during the polymerization and at different polymerization temperatures. The amounts of polymerization initiator used are generally from 0.01 to 2 wt .-% based on the monomer mixture.

The polymerization is usually carried out in such an arrangement of the chambers, which ensures a temperature control or heat dissipation, so can - lying horizontally in racks - chambers, for example in hot air ovens at high air velocity, in autoclaves using water spray or in water-filled tanks under polymerization being held. The polymerization is initiated by heating. To dissipate the considerable heat of polymerization, especially in the gel area, targeted cooling is necessary. The polymerization temperatures are usually between 15 and 70 ° C at atmospheric pressure. In the autoclave, they are expediently about 90 to 100 ^° C. The residence time of the polymerization chamber in the temperature control medium varies according to the manner of the polymerization batch and the reaction between a few hours and several days.

In addition to the polymerization initiator further additives such. B. molecular weight regulator, z. As dodecylmercaptan be added. Preferably, however, polymerized without molecular weight regulator to realize high molecular weights.

In the interests of the widest possible reaction (> 99% polymer), the temperature should be increased again for a short time towards the end of the polymerization, for example to about 100 ⁰ C _{1 to} about 120 ⁰ C. It is expedient to cool slowly, with the polymer plates separated from the mold plates and can be removed. When the polymerization chamber is filled with the monomer liquid, it penetrates into the cavities of the coating of the substrate. SiO ₂ and antimony-tin oxide may, for. Example in the form of an interpenetrating network. During the polymerization, therefore, there is a certain penetration of the inorganic layer with the resulting polymer of the plastic body. Thus, a coating structure is formed which differs structurally from post-applied coatings as known in the art.

Optionally, a so-called "tempering" may take place, in which the plastic bodies are preferably left in the polymerization chamber after the polymerization and after cooling are heated again for, eg, 2 to 8 hours to 40 to 120 ^° C. escape and internal stresses in the plastic body can be lowered.

Process step f):

Removal of the coated plastic body with single or multi-sided inorganic coating from the polymerization chamber.

After dismantling or opening the polymerization chamber, the plastic body can be removed with one-sided or multi-sided inorganic coating. Preferably, a polymethyl methacrylate plastic plate is produced with one- or two-sided electrically conductive coating. Plastic body

The plastic body obtainable by the process according to the invention preferably has an electrically conductive coating having a surface resistance of less than or equal to 10 ¹⁰ _1, preferably less than or equal to 10 ⁷ , and contains 0.16 to 0.28, preferably 0.18 to 0.25 Wt .-% of a release agent mixture of a C ₆ - C ₂ o-alkyl sulfosuccinate, preferably a Cs - C-io-alkyl sulfosuccinate and a Ce - C ₂ o-alkyl phosphate, preferably a C ₈ - Cio-alkyl phosphate.

A tyndall effect that indicates a cloudiness is not recognizable. Rainbow interference effects, which indicate an uneven layer distribution, are hardly or not at all visible on the coated surfaces. The determination of the surface resistance of the coating may, for. B. according to DIN EN 613402 / IEC 61340 with an ohmmeter from the company. Wolfgang Warmbier, model SRM-110 be performed.

The plastic body is preferably made of a polymethylmethacrylate, d. H. a polymer which is predominantly composed of methyl methacrylate or a polystyrene. The plastic may contain additives and auxiliaries such as impact modifiers, pigments, fillers, UV absorbers, etc. The plastic body may also be translucent or transparent.

The layer thickness of the electrically conductive coating is in the range from 200 to 5000, preferably 250 to 1000, particularly preferably in the range from 300 to 400 nm. The plastic body has on the inorganic coated surface a rubbing resistance according to DIN 53 778 of at least 10,000, preferably at least 12,000, in particular at least 15,000 cycles. The determination of the adhesion of the coating according to the wet rub test according to DIN 53778 can z. B. with a wet scrub tester from. Gardner, model M 105 / A are performed.

The Kunststofϊkörper can be used for. For enclosures, clean rooms, machine covers, incubators, displays, screens and screen covers, rear projection screens, medical equipment and electrical appliances.

Advantageous Effects of the Invention

The process according to the invention makes it possible to produce plastic bodies having a coating structure which differs structurally from subsequently applied coatings, as known from the prior art.

The coating transferred from the coated substrate to the polymer plastic body during its polymerization is of high quality. A Tyndall effect, which would indicate a cloudiness is not recognizable. Rainbow interference effects, which indicate an uneven layer distribution, are hardly or not at all visible on the coated surfaces. The abrasion resistance is increased compared to conventionally coated Kunststoffkörpem. The plastic body can be easily removed from the polymerization, so that the process can be operated as a whole uncritically and in large series largely without interference. Examples

example 1

25 parts by weight of an anionic silica sol (solids content 30%, © Levasil available from Bayer AG) were mixed with 0.4 parts by weight of an ethoxylated

Fatty acid alcohol (© Genapol X80) with 100% deionized water

Parts by weight and with a solution consisting of 0.5 parts by weight

(O-ethyldithiocarbonic acid (3-sulfopropyl) ester, potassium salt; © Raschig OPX available from Raschig AG) with aqueous NaOH solution at a pH of

9 to 100 parts by weight, in the ratio 1: 1, 5 mixed.

50 parts by weight of this first solution was mixed with 50 parts by weight of

Antimony Tin Oxide Solution (12% in water, available from Phosphor

Breitungen GmbH) mixed.

The coating composition thus prepared was then applied by flooding on a glass plate and dried for 3 h at 100 ⁰ C. The coated ones

Glass panes were used for the construction of a polymerization chamber with a circulating cord.

In the polymerization chamber is a polymerizable solution of methyl methacrylate, the 0.1 wt .-% of a polymerization initiator (2,2'-azobis (2,4-dimezhylvaleronitrile)) and a release agent mixture of 0.05 wt .-% Diisooctylsuccinat and 0 , 15 wt .-% of a mixture of Monononylphosphat and Dinonylphoshat contains filled. The chamber is incubated in a water bath at 50 ⁰ C for 3 hours, then the clamp fixation removed and then annealed for 3.5 h at 115 ⁰ C in a drying oven. In the polymerization of the methyl methacrylate, the coating is transferred from the glass felts to the polymethylmethacrylate (PMMA) surface. The coated polymethyl methacrylate plate is light from the glass sheets removable, can be removed from the chamber without glass breakage or breaking of the polymethylmethacrylate on the edge and shows a good appearance, without turbidity or streaks.

The determination of the layer thickness of the extremely thin layers can be carried out by thin section in a transmission electron microscope. The thickness of the layer was in the range of 350 to 400 nm depending on the flood direction.

The determination of the adhesion of the coating was carried out according to the wet scrub test according to DIN 53778 with a wet scrub tester from Gardner, model M 105 / A. A value of 20,000 cycles at a total layer thickness of 350 nm was determined.

The surface resistance of the coating was determined in accordance with DIN EN 613402 / IEC 61340 using an ohmmeter from Wolfgang Warmbier, Model SRM-110. A value of 10 ⁶ Ω at a total layer thickness of 350 nm was determined.

The plate showed good optical properties.

Comparative Example 1

Example 1 was essentially repeated except that the coating agent was applied directly to the PMMA plate by means of flooding. The thus coated plate was then dried at 80 ° C for 30 minutes.

The adhesion of the coating proved to be non-durable and could be removed by means of a conventional wipe by repeated rubbing of the PMMA plate. Comparative Example 2

Comparative Example 1 was substantially repeated, but the PMMA plate was first equipped with an adhesion-promoting layer (PLEX 9008L, available from Röhm GmbH & Co. KG) and then the coating agent was applied by the flood process. The thus coated plate was then dried for 30 min at 8O ⁰ C.

The adhesion of the coating proved to be non-durable and could be removed by means of a conventional wipe by repeated rubbing of the PMMA plate.

Comparative Example 3

Example 1 is substantially repeated except that the composition of the coating composition is changed so that the antimony-tin-oxide solution (12% in water, available from Leuchtstoffwerk Breitungen GmbH) is applied directly to the glass plate. It is not possible to obtain a uniform course of the coating.

The transfer of the coating to the PMMA plate is uneven. In some cases, there are strong interferences in the form of rainbow colors, which indicates layer thickness variations of the coating. Comparative Example 4

Example 1 is substantially repeated except that the composition of the coating agent is changed to use 95 parts by weight of the first solution and 5 parts by weight of the antimony-tin oxide solution (12% in water, available from Leuchtstoffwerk Breitungen GmbH) ,

After transferring the coating to the PMMA plates, the coated plates show turbidity (Tyndall effect). The surface resistance is> 10 ⁹ Ω.

Comparative Examples 5-16

Example 1 was repeated but with different release agents or other release agents. The results are shown in the table below. Diisooctylsuccinate alone (Ex 5 to 10), mono- and dinonyl phosphate alone (Ex 11), other release agents (Ex 12 - 15) or too low a content of mono- and dinonyl phosphate in the release agent mixture (Ex 16) led to unsatisfactory results. For comparison, Example 1 is given again in the last line. TT o

O

ΪΛ

O O

W H U

O

IΛ

O O

W H U

Claims

1. A process for producing a plastic body from a plastic obtainable by free-radical polymerization with single or multi-sided inorganic coating by the method steps

a) coating of a substrate by means of knife coating, flooding or dipping with a coating composition comprising a silicon-based adhesion promoter and inorganic particles in a weight ratio of 1: 9 to 9: 1 in a solvent, which may optionally contain additional flow control agents, b) C) use of one or more substrates coated in such a manner to build up a polymerization chamber, wherein the coated sides lie inside the chamber, d) filling a polymerizable liquid from radically polymerisable monomers, c) drying the coating composition on the substrate optionally with polymer content in the polymerization chamber, wherein the polymerizable fluid from 0.16 to 0.28 wt .-% of a release agent mixture of a C ₆ - C ₂ o alkyl sulfosuccinate and a Ce - C contains ₂ 0-alkyl phosphate, e) Radical Polymerization of the polymerizable liquid t in the presence of a polymerization initiator, wherein the internal inorganic coating passes from the substrate into or onto the surfaces of the free-radically polymerized plastic or the plastic body, and f) removal of the coated plastic body with one-sided or multi-sided inorganic coating from the polymerization chamber.

2. The method according to claim 1, characterized in that the plastic body has the shape of a flat plate.

3. The method according to claim 1 or 2, characterized in that the plastic obtainable by free-radical polymerization is a polymethyl methacrylate or a polystyrene.

4. The method according to one or more of claims 1 to 3, characterized in that the adhesion promoter consists of colloidally dissolved SiÜ ₂ particles or silane condensates.

5. The method according to one or more of claims 1 to 4, characterized in that the lacquer composition, 1 to 2 wt .-% SiO 2 particles and 2.5 to 7.5 wt .-% antimony tin oxide particles in Contains water as solvent.

6. The method according to claim 5, characterized in that the coating composition additionally contains a surfactant or mixtures of surfactants as leveling agents.

7. The method according to one or more of claims 1 to 6, characterized in that the substrate to be coated is a glass plate, a plastic plate or a plastic film.

8. The method according to claim 7, characterized in that the plastic plate or plastic film consists of polyethylene terephthalate.

9. The method according to one or more of claims 1 to 8, characterized in that the substrate is dried with the paint composition at a temperature in the range of 80 to 120 ⁰ C.

10.Verfahren according to one or more of claims 1 to 9, characterized in that the polymerizable liquid is polymerized at 40 to 8O ⁰ C.

11.Verfahren according to one or more of claims 1 to 10, characterized in that a polymerization chamber, consisting essentially of two plates with circumferential sealing cord is used.

12. The method according to one or more of claims 1 to 11, characterized in that a polymethyl methacrylate plastic plate is produced with one- or two-sided electrically conductive coating.

13. The method according to one or more of claims 1 to 11, characterized in that the polymerizable liquid in process step d) contains a release agent mixture of Na- Diisooctylsulfosuccinat and a mixture of monononyl and dinonyl phosphate.

14. Plastic body, obtainable by a process according to one or more of claims 1 to 13.

15. Plastic body according to claim 14, characterized in that it has an electrically conductive coating having a surface resistance of less than or equal to 10 ¹⁰ Ω and 0.16 to 0.28 wt .-% of a release agent mixture of a C ₆ - Cao alkyl sulfosuccinate and a C ₆ - C _2O- AII kyl phosphate.

16. Plastic body according to claim 14 or 15, characterized in that the layer thickness of the electrically conductive coating in the range of 200 - 5000 nm.

17. Plastic body according to one or more of claims 14 to 16, characterized in that the inorganic coated surface has a rub resistance according to DIN 53 778 of at least 10,000 cycles.

18. Use of the plastic body according to one or more of claims 14 to 17 for enclosures, for the equipment of clean rooms, for machine covers, for incubators, for displays, for screens and screen covers, for rear projection screens, for medical equipment and for electrical appliances.

19. The use of a release agent mixture of a C ₆ - C ₂₀ - alkyl sulfosuccinate and a C ₆ - C ₂ O-AI alkyl phosphate in a polymerizable liquid of radically polymerizable monomers, optionally with polymeric component, for the purpose of improving the detachment of the casting process, in particular according to claims 1 to 13, produced plastic body from the polymerization chamber.