NL9400692A - Colored polymeric moldings and method for their manufacture. - Google Patents

Description

Colored polymeric moldings and method for their manufacture

The invention relates to polymeric shaped parts of highly filled casting resins with metallic shiny, optionally colored surfaces, the surface effect of which is obtained by means of lacquering and fixed.

Already in German patent 693 824 it is described that dye-containing layers in polymer molded parts which are produced in the mold by polymerization are embedded close to the surface by such dye-containing layers which are almost insoluble in the polymerized compounds binder, to be applied to the walls of the mold and then, after filling with the polymerization, liquid compounds to carry out the polymerization in a known manner. The dye-containing layers may be evenly or unevenly distributed and, for example, may be multi-colored using different dye-containing layers. The proposal also includes the use of (organic) solvents for the binders used. On the other hand, after-treatment, such as applying a coating, is unnecessary.

DE-A-30 23 964 describes a process for obtaining colorant-containing zones in acrylic and methacrylic resins near the surface by the polymerization of the resin-forming monomers and prepolymers in molding polymerization chambers, first coatings homogeneously distributed in a binder on the walls of the shaping polymerization chamber, the binder being soluble in the liquid resin or its precursors, or at least swelling, and monomers and / or prepolymers known per se after polymerization to resins.

From EP-A-061 245 a method for the production of a molded article is known, wherein the composition is cured in a mold containing at least two moldings, which define a hollow space, and wherein when the curable composition is introduced into the hollow space of the mold, at least a part of the surface that forms the hollow space of the mold, is provided with a partition consisting of a material which, with the curable composition, provides a color contrast, whereby the partition is applied to surfaces of the mold which correspond to the surfaces on the cured shaped article on which a color contrast is to be formed, and characterized in that the separation of at least one finely divided pigment in a mixture with at least one finely divided filler with an average particle size of 100 µm or smaller and that the mixture is applied as a suspension in a volatile carrier material.

EP-A-0 217 544 describes a method for the production of moldings from curable compositions with surface areas. which have color contrasts, wherein one surface of the mold prior to filling with the curable compositions with a colorant consisting of a) comprises at least 25% by weight of a liquid carrier, with 0-100 parts by weight of a polymerizable liquid and 100% by weight. 0 parts by weight of a non-polymerizable organic liquid, b) 0.1-10% by weight of an inorganic pigment or 0.0001-1% by weight of organic dyes, c) 0-60% by weight of a finely divided filler, d) 0.1-50 # of a carrier a) soluble drying alkyd resin and e) a liquid soluble polymer is coated.

EP-A-0 526 818 discloses a process for the production of polymeric moldings of highly filled casting resins with different surface areas in color, wherein one surface of the mold before filling with the casting resin, such as with a curable coating of a color The composition containing the composition is coated to produce a color difference, the coating being applied in at least two coating steps to the designated surface areas of the mold and, after drying of the lacquer layers, the mold is filled with the casting resin and polymerized under heating and finally released.

A special pigment coloring, for example of printing inks or varnishes, can be achieved with pearlescent pigments, the so-called effect pigments. The effect of the pearl luster, a metallic luster, is very popular for decorative purposes.

Acrylic resin with a gloss effect can be prepared by conventional addition, for example by stirring, of pearl gloss pigment to the methyl methacrylate mass to be polymerized. In this conventional process, however, hardened articles cannot be obtained from highly filled systems with metallic luster surfaces caused by pearl luster pigment.

The object of the invention is to provide articles of hardened filled systems which have metallic glossy surfaces as a result of pearlescent pigment, and to provide a suitable preparation method for this purpose. Such cast resin articles are of particular importance in the sanitary sector. To this end, they must be provided with a uniform metallic glossy-looking surface layer with a sufficient depth of color or pigment to prevent bleaching under the influence of moisture ("water-whitening").

According to the invention, novel planar articles containing pearlescent pigment colored and metallic glossy surfaces can be obtained from cured highly filled casting resins. In terms of properties, they largely meet the requirements. It has surprisingly been found that the novel homogeneously colored articles can be produced by analogy to the process for the production of polymer molded parts casting resins with different surface areas according to EP-A-0 526 818.

The invention relates to polymeric molded parts of highly filled casting resins with metallic glossy surfaces, characterized in that the metallic glossy surface is a pearl luster pigment-containing coating. The pearl luster pigment can be colored.

The invention furthermore relates to a process for the production of the new polymeric molded parts of highly filled casting resins with metallic shiny, optionally colored surfaces, characterized in that one surface of the molding mold is filled with a casting resin before filling with the resin. curable pearlescent pigment containing lacquer composition L is applied and the mold is filled with the casting resin after drying of the lacquer layer and polymerized under heating and finally discharged. The casting resins are preferably those from the class of acrylic resins. In addition to the pearl gloss pigment-containing lacquer L, a further lacquer pigment-free lacquer-free lacquer L 'is optionally used for the production of the surface.

In the method according to the invention, to obtain the metallic shiny surfaces - as already explained - use is made of a varnish in at least one stage, optionally in two stages. In the actual lacquer layer, a lacquer dispersion L with the pearl gloss pigment addition is used. The construction of the lacquer dispersions L and optionally of L 'furthermore involves binders B and liquid carrier constituents T.

The pearlescent pigments to be used in the process according to the invention for the formation of the metallic glossy surfaces of the new polymer-formed parts are white and colored pearlescent pigments based on mica or titanium dioxide or iron (III) oxide with a grain size in the range from 0.1 to about 50 μιη. For example, known pearl gloss pigments are used on an industrial scale under the brand name Iriodir®. They are used in printing inks, plastic inks and paints, such as car paints. The color effects of these pigments are caused by light absorption and interference. Pearlescent pigments with a certain thickness of the particles meet the interference conditions and show iridescent colors.

According to the invention, with Iriodir® 9111 Rutil Feinsatin WR, a polymer-shaped part with a very uniform, highly shiny and silver-colored metal effect surface is obtained. When red Iriodii® 9514 Silkrot WR II is used, a part with a strongly glossy, dark red and metal effect-displaying surface is obtained after the polymer-formed part has been released.

Generally, pearl gloss pigment G or filler F and binder B are used in a ratio of 1: 1 to 20: 1 parts by weight, preferably from 2: 1 to 10: 1 parts by weight. Approximately, the eligible binders B can be incorporated into polymeric binders (B-P) and reactive binder systems (B-R) (compare H. Wagner and H.F. Sarx, Lack-Kunstharze, Carl Hanser Verlag, Munich 1959). which are soluble in the carrier component T. The polymeric binders B-P may suitably belong to the same class of polymers as the casting resins themselves. For example, they are selected from the group of poly (meth) acrylates, especially polymethyl methacrylate and its copolymers.

Generally, the molecular weight Mw of the polymeric binders is in the range of 10,000-1,000,000, preferably in the range of 100,000-500,000 Daltons, with the criterion of solubility in the carrier component T being met. The binder B D is dissolved in a suitable solvent, preferably in the carrier component T. The presence of the polymeric binders B-P is not absolutely necessary, however at least one reactive binder system B-R is required for curing. These systems can consist of only one reactive binder, for example an alkyd resin, such as, for example, Alkydal® F26, or of two or more components, which harden under the prevailing conditions (compare H. Wagner, HFSarx, Lackkunstharze loc.cit; Kirk -Othmer, Encyclopedia of Chemical Technology, 3 * ed., Vol. 6, pp. 427-445, J. Wiley 1979).

Applicable binders can be selected from the class of the polycondensation resins, the polyaddition resins and the polymerization resins. Mentioned, for example, are the groups of the alkyd resins, in particular oil-modified, for example, the oxidized alkyd resins, alkyd resins plus diisocyanate "plus chlorinated plastics" plus polystyrene "plus nitrocellulose vinyl and epoxy resin "plus aminoplasts (plus epoxy resin)" plus siloxane oil-modified epoxy resins plus aminoplasts. The oil content may be 20-80 wt%.

phenoplasts (with or without epoxy, vinyl acetal or aminoplast component) vinyl acetals with or without phenolic allylaminoplastic component polyester and triazine resins allyl polyester complex amino resins indene and coumarone resins.

Mention may be made, for example, of binders BR which are formed from, for example, an aromatic polyisocyanate (e.g. commercial products of the type DESMODUB® from Bayer AG) and polyesters or polyethers with free hydroxyl groups (e.g. commercial products of the type DESMOPHEN® from Bayer AG) or binders produced by reaction of polyisocyanates with acrylic resins containing hydroxyl groups (for example, commercial product JAGOTEX® F232 from Jager, Pabrik chemischer Roh-stoffe) are obtained. For three-dimensional cross-linking, at least one of the reaction components must contain three or more reactive groups in the molecule. Lacquers L and optionally L 'may also contain functionalized monomers, such as (meth) acrylic acid, for improving adhesion in amounts of 0 to 50% by weight, based on the binders B-P + BR, known per se cross-linking monomers (compare Rauch-Puntigam, Acryl- und Methacrylverbindungen,

Springer-Verlag 1967), for example (meth) acrylic acid esters of polyhydric alcohols (polyols) such as glycol dimethacrylate and the like, usually in amounts of less than 15% by weight. As binders are mentioned, for example, combinations of binders BP, such as polymethyl methacrylate, optionally with a comonomer content - usually less than 15% by weight -, for example methyl acrylate, 2-ethylhexyl (meth) acrylate and the like, with a binder BR is formed from, for example, an aromatic polyisocyanate (for example, commercial product DESMODUF® N75) and polyacrylate containing monohydroxyl (commercial product JAG0TE5® F232). As an indication of the use, a weight ratio of BP: B-R of (3-1): 1 is indicated.

The liquid carrier component T in the lacquer L guarantees the sprayability to volatilize after a certain, suitably chosen (drying) time. The carrier component T consequently has as an indication a boiling point (under normal conditions) in the range of 50-220 ° C, preferably in the range of 75-170 ° C. Optionally, the combination of a component with a high and a component with a low boiling point lead to the target The carrier component T may therefore be suitably selected from the group consisting of - monomers, especially under the influence of free radical polymerizable monomers, for example of the type of the (meth) acrylic acid esters, in particular with alkyl radicals, very in particular Cx or C2 ester (= TM), solvents, for example of the type of the (aromatic) hydrocarbons, of the ketones (= TL).

As an additional criterion for the choice of the carrier component T-L, an evaporation number (based on ether = 1) of 2-100, in particular of 2.5-50, can be used. The evaporation number is defined as the time in which a certain amount of solvent (usually 0.3 ml applied in 5 seconds from a distance of 10 mm on filter paper) compared to diethyl ether. (Compare DIN 53 170; Ullmanns Ecyclop & die der Techn. Chemie, 4th edition, part 16, page 289, V.C.

1978).

As examples of the carrier component T-M are mentioned methyl methacrylate, methyl acrylate, ethyl methacrylate, n-butyl methyl acrylate and the like. As examples of the carrier component T-L are listed butyl acetate, ethoxyethyl acetate and the like, and hydrocarbons such as, for example, Shellsol®. A combination of T-L + T-M can be expedient.

The content of the carrier component T in the lacquer is generally in the range of 40-90% by weight, the proportion of the polymeric binder BP is 0-20, preferably 0.5-10, in the especially 1-10 wt. /. The proportion of the pearl luster pigment in the sprayable lacquer L is usually in the range of 1-20 w / w, preferably 2-15 w / w. A typical composition of the lacquer L may therefore be: about 70 parts by weight of methyl methacrylate 5 parts by weight of PMMA20 parts by weight of pearlescent pigment 5 parts by weight of alkyd resin, for example Alkydal® F26

As solvents for formulating the sprayable lacquer, solvents already mentioned at T are used, for example butyl acetate, ethyl acetate and / or monomer, such as MMA and / or Shellsol® A. They are, for example, with the formulation according to the above lacquer recipe in a weight ratio of 1: 2 and, with the addition of about 1 to 2 parts by weight per 100 parts by weight sprayable lacquer, of the polymerization under the influence of a radical initiating initiator, processed into a sprayable lacquer.

For the preparation of the lacquer L, it is possible, for example, to work in such a way that all constituents except the binder B-Rin are dissolved in the carrier component T by means of a paddle stirrer, then add the Iriodir® and intensively distributed with the paddle stirrer . Finally, the binder B-R is added and dissolved.

According to the prior art, casting resins according to the prior art are understood to mean liquid, die-cast, hard-resin resins from which the polymer-formed parts are formed from which are cured. Highly suitable casting resins G and corresponding preper polymers can be obtained from European Patent Specification 218 866 or US-A-4 786 660 or US-A-4 221 697 and US-A-4 251 576 respectively. Preferably the casting resins G up to the class of the acrylic resins, and particularly preferably these are polymers based on methyl methacrylate, whereby a mixture of a prepolymer and the monomers is expediently used. Preferably, the filler containing "filled" casting resins, in particular highly filled casting resins, especially casting resins, the fillers constituting an amount of 50-80% by weight, based on the casting resin. Suitable fillers F are the corresponding fine particulate inorganic or organic materials used for casting resins. An average grain size of 100 µm diameter is expediently not exceeded. Granular particles are preferred. Sometimes it may be expedient to free the particles from adsorptively bound moisture by heating, for example up to 250 ° C. Fillers F can be natural products or prepared synthetically. The mechanical properties, such as hardness, elastic shear modulus, depend on the intended application of the casting resins. In addition, the adjustment of an elastic shear modulus of at least 5 GNm2 may be effective. Suitable, for example, are minerals such as aluminum oxides, aluminum hydroxides and derivatives, for example, alkali metal and alkaline earth metal double oxides and alkaline earth metal hydroxides, clays, silicon dioxide in its various modes, silicates, alumosilicates, carbonates, phosphates, sulfates, sulfides, oxides, carbon, metals and metal alloys. Furthermore, synthetic materials such as ground glass, ceramics, porcelain, slag, finely divided synthetic SiO2 are suitable. Silica modifications such as quartz (quartz powder), tridymite and cristobalite, as well as co-kaolin, talc, mica, feldspar, apatite, barite species, gypsum, chalk, limestone, dolomite are mentioned. Mixtures of fillers may also be used. The filler content in the casting resins is generally at least 20% by weight. In general, a content of 80% by weight is not exceeded. As a guide value, a filler content in the casting resins of 50-80% by weight is indicated. The preparation of the fillers in the effective grain sizes can be carried out according to known methods, for example by crushing and grinding. Particular preference is given to crystallite and aluminum hydroxide.

The implementation of the method according to the invention requires the usual molds and spraying devices. The application details can be effectively determined on a metal plate (for example, on a nickel-plated, highly polished brass plate). 85 ° C can be specified as the preferred temperature for the metal surfaces intended for application. It is recommended to first heat at this temperature for about 30 minutes, for example in a drying cabinet.

Application can be carried out with a suitable spray gun (for example brand SATA Minijet), for example with a nozzle of 0.8mm and a pressure of 2.5 bar. The individual lacquer layers are expediently applied by spraying the lacquers L 'and L twice over the entire surface of the metal plate. The lacquer time is generally 2-2.5 minutes. Immediately after the last painting, the object is put back in the oven (drying cabinet) at 85 ° C. In a short time, for example less than 5 minutes, it is then expediently filled with the casting resin G. The method is further explained by means of a filler containing PHMA / MMA casting resin. For example, in about 3 minutes the metal plate provided with the lacquering, a suitable second non-lacquered metal plate (indication 350 x 350 x 4 mm) and a sealing cord (for example PVC cable with a diameter of 4 mm) are prepared. mold chamber, which is filled with the highly filled, optionally colored (degassed) casting resin with, for example, PMMA / MMA as a curable synthetic resin and with at least one radicalization-initiating polymerization initiator, for example a perester, such as bis- (4- tert-butylcyclohexyl) -peroxydicarbonate, in conventional amounts (e.g., 0.5 * 5 wt.%, based on the monomers) in a short time, e.g., about 1.5 minutes. After the mold chamber has been closed, it is expedient to first use a horizontal position of the mold chamber at an elevated temperature - for example at about 65 ° C and in a water bath and, with the lacquer-coated side down, for approx. 20 minutes and subsequently at an even higher temperature, for example at 105 ° C, preferably tempered in a drying cabinet for 15 minutes. The polymer-formed part is then taken out of the mold chamber at a temperature of about 60 to 70 ° C.

With the method according to the invention, new polymeric molded parts of casting resins with a metallic shiny, optionally colored and very uniform metal effect of the surface are obtained. Seven tones even with long-term storage in water - test: 24 hours in 90 ° C hot water - no white coloring of the surface, the so-called "water-whitening" effect.

The following examples and data for the preparation of the polymer molded parts are intended to illustrate the invention.

Examples A) Preparation of the spray paint L Example I:

5.0 parts by weight of a polymethyl methacrylate with a content of 10% by weight of methyl acrylate (Mw = about 350,000) are dissolved in 71 parts by weight of methyl methacrylate. 1 part by weight of glycol dimethacrylate, 3 parts by weight of Alkydal® F26 (60% in xylene, a product of BAYER AG) are added to this solution and dissolved. To this syrup, 20 parts by weight of Iriodirf® 9111 Rutil FeinsatinWR (Merck company) are added to this syrup while stirring with a paddle stirrer. The stirring time is about 30 minutes. To 50 parts by weight of this Iriodin-containing lacquer, 12.5 parts by weight of Shellsol® A (Shell company), 12.5 parts by weight of n-butyl acetate and 1 part by weight of Interoa® BCHPC = bis- (4-tert-butylcyclohexyl) peroxydicarbonate from Peroxid-Chemie GmbH added and dissolved.

Example II:

The same procedure as in Example II, instead of Iriodir® 9H1Rutil Feinsatin WR, the same amount of Iriodir® 951 * 1 Silkrct WRII was used.

B) Preparation of the spray paint L '

In 75 parts by weight of methyl methacrylate, 5.0 parts by weight of a polymethyl methacrylate with a content of 10 wt. JU of methyl acrylate (Mw * about 350,000) is dissolved and 25 parts of silanized cryobalite (product SILB0ND® 6000 MST from Quarzwerke Frechen) are dispersed with a dissolver at about 10.0 m / s for 15 minutes. 1 part by weight of glycol dimethacrylate and 3 parts by weight of Alkydal® F26 (60 # in xylene, a product of BAYER AG) are added to this suspension and dissolved.

12.5 parts by weight of Shellsol® A (Shell company), 12.5 parts by weight of n-butyl acetate and 1 part by weight of Interoj® BCHPC = bis- (4-tert-butylcyclohexyl) are added to 50 parts by weight of this cristobalite-containing lacquer. peroxydicarbonate from Peroxid-Chemie GmbH added and dissolved.

C) The highly filled casting resin

50-80 parts by weight of an inorganic filler are dispersed in a prepolymer pre-solution, for example 40 parts by weight of a solution of MMA / PMMA (weight ratio 35: 5) which still contains cross-linking agent and optionally a silane with a silanation catalyst. Cristobalite or aluminum hydroxide is preferably used. In addition to release agents, such as stearic acid, the casting resin also contains a polymerization initiator, such as, for example, bis- (4-tert-butylcyclohexyl) -peroxydicarbonate or a conventional redox system.

D) Manufacture of the polymeric shaped parts

The manufacture of the polymeric shaped parts has been described above.

E) Testing the molded parts for "water whitening"

Test objects measuring 50 x 50 mm are cut from cast plates.

The test objects are stored in water at a temperature of 90 eC for 24 hours. After a further storage time of 24 hours at room temperature, in air, the samples are compared with a fresh sample.

Result:

The formed parts according to the invention show virtually no fading after treatment with water compared to fresh samples. Hardened casting resins without a pearlescent pigment coating show significant bleaching after the water whitening test.

Claims (13)

1. Polymeric shaped parts of highly filled casting resins with metallic shiny surfaces, characterized. that the metallic glossy surface is a pearl gloss pigment containing coating. 2. Polymeric shaped parts according to claim 1, characterized in that the metallic glossy surface is formed with a colored pearlescent pigment. Polymer shaped parts according to claims 1 and 2, characterized in that the casting resin contains PMMA / MMA as curable synthetic resin. 4. Method for the production of polymer-shaped parts of a highly filled casting resin with metallic shiny, optionally colored surfaces, characterized in that on one surface of the molding mold, prior to filling with the casting resin, a curable layer of a pearlescent pigment containing lacquer composition L is applied and the mold is filled with the casting resin after drying of the lacquer layer and polymerized under heating and finally discharged. Method according to claim 4, characterized in that, before the lacquer composition L is applied in a first lacquer step, a lacquer L 'without pearl gloss pigment addition, which however contains a filler, is applied and then dried. 6. A method according to claim 4 or 5, characterized in that the lacquer L contains, in addition to the pearlescent pigment, binders B and at least one liquid carrier component T. A method according to any one of claims 4-6, characterized in that the binders B, apart from the curable system B-R, also consist of a polymer binder B-P. 8. Process according to claim 7, characterized in that the polymeric binder B-P is a homo- or copolymer of methyl methacrylate. 9. A method according to any one of claims 4-6, characterized in that the liquid carrier component T has a boiling point under normal conditions in the range of 50-200 ° C. Process according to claim 9 *, characterized in that the liquid carrier component T has a boiling point under normal conditions in the range of 75-170®C. A method according to any one of claims 4, 9 and 10, characterized in that. that the carrier component T consists wholly or partly of radion-polymerizable monomers. Process according to claim 11, characterized in that the carrier component T consists wholly or partly of one or more alkyl esters of (meth) acrylic acid with 1 to 6 carbon atoms in the alkyl radical. 13. Process according to claim 11, characterized in that the carrier component T consists entirely or partly of methyl methacrylate.