CH686498A5 - Polymerisatformstuecke with metallic gleaming, optionally colored surfaces. - Google Patents

Description

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description

The invention relates to polymer moldings made from highly filled casting resins with shiny metallic, optionally colored surfaces, the surface effect being produced and fixed by means of painting.

German patent 693 824 already describes that dye-containing layers can be embedded in polymer moldings which are produced in the mold by polymerisation, just below the surface, by using such dye-containing layers which contain a binder which is practically insoluble in the compounds to be polymerized. applies to the mold wall and then carries out the polymerization in a known manner after filling in the liquid compounds to be polymerized.

The dye-containing layers can be uniformly or unevenly distributed and using different dye-containing layers, e.g. be multicolored. Among other things, also the use of (organic) solvents for the binders used. A post-treatment such as the application of a top coat is, however, unnecessary.

DE-A 3 023 964 describes a process for producing colorant-containing zones in acrylic and methacrylic resins near the surface in the course of the polymerization of the monomers and prepolymers forming the resins in shaping polymerization chambers, which is characterized in that firstly, colorants homogeneously distributed in a binder applied to the wall of the shaping polymerization chamber as a layer, the binder being soluble or at least swellable in the liquid resin or its precursors, and that after filling in the monomers and / or prepolymers to be polymerized, polymerization is carried out in a manner known per se to give resins.

EP 061 245 discloses a process for forming a molded article, in which the composition is cured in a mold which has at least two molded parts which define a cavity, and in which at least part of the introduction of the curable composition into the mold cavity the surface forming the mold cavity is provided with a deposit made of a material which provides a color contrast with the curable composition, the deposition being specified on surfaces of the mold which correspond to the surfaces on the hardened molded article on which a color contrast is formed and that is characterized in that the deposition consists 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 less and that the mixture is applied as a suspension in a volatile carrier material.

EP-A 0 217 544 describes a process for the production of moldings from curable compositions with surface areas which have color contrasts, a mold surface before the curable compositions are filled with a colorant, consisting of a) at least 25% by weight of a liquid carrier, the 0-100 parts by weight of a polymerizable liquid and 100-0 parts by weight of a non-polymerizable organ. Liquid b) 0.1-10% by weight of an inorganic pigment or 0.0001-1% by weight of organ. Dyes c) 0-60% by weight of a finely divided filler, d) 0.1-50% of a drying alkyd resin which is soluble in the carrier and e) a polymer which is soluble in the liquid.

EP-A 0 526 818 discloses a process for producing polymer moldings from highly filled casting resins with color-differentiated surface areas, in which a surface of the shaping tool is coated with a curable coating of a colorant-containing composition before being filled with the casting resin in such a way that color Differentiation arises, the coating being applied to the intended surface areas of the tool in at least two painting steps and, after the paint layers have dried, the tool is filled with the casting resin and polymerized with heating and finally removed from the mold.

A special pigment coloring, e.g. Printing inks or varnishes can be achieved with pearlescent pigments, the so-called effect pigments. The pearlescent effect, a metallic sheen, is very popular for decorative purposes.

Acrylic glass with a glossy effect can be added by usual addition, e.g. be prepared by stirring pearlescent pigment into the methyl methacrylate mass to be polymerized. In this usual procedure, however, highly filled systems cannot produce hardened objects with metallic, glossy surfaces caused by pearlescent pigment.

Due to the pearlescent pigment, objects made of hardened, highly filled systems with shiny metallic surfaces had to be provided after finding a suitable manufacturing process. Such cast resin objects are of particular interest in the sanitary area. To do this, they must be provided with a uniformly shiny metallic surface layer of sufficient color or pigment depth in order to be able to effectively counteract the fading under the influence of moisture ("water-whitening").

According to the invention, novel objects made of hardened, highly filled casting resins can be provided which are colored with pearlescent pigment and have metallic shiny surfaces. In terms of their properties, they largely meet the requirements. Surprisingly, it was found that the new, uniformly colored objects lean on each other

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that can be produced for the production of polymer moldings from casting resins with color-differentiated surface areas according to the method known from EP-A 0 526 818.

The invention relates

Polymerization moldings made of highly filled casting resins with shiny metallic surfaces, characterized in that the shiny metallic surface is a coating containing pearlescent pigment. The pearlescent pigment can be colored.

The invention further relates to a method for producing the new polymer moldings from highly filled casting resins with shiny metallic, optionally colored surfaces, which is characterized in that a surface of the shaping tool is coated with a curable pearlescent pigment-containing lacquer composition L before being filled with the casting resin and after the paint layer has dried, the tool is filled with the casting resin and polymerized with heating and finally removed from the mold. Casting resins of the acrylic resin class are preferably used. If necessary, in addition to the pearlescent pigment-containing lacquer L, a further pearlescent pigment-free but filler-containing lacquer L 'is also used for the surface production.

The process according to the invention makes use of at least one one-step or, if necessary, two-step painting to obtain the shiny metallic surfaces. In the main painting step, a paint dispersion L with the pearlescent pigment additive is used. Binder B and liquid carrier components T are also involved in building up the lacquer dispersions L and, if appropriate, L '.

The pearlescent pigments to be used in the process according to the invention for the formation of the shiny metallic surfaces of the new polymer moldings are white and colored pearlescent pigments based on mica or titanium dioxide or iron (III) oxide with grain sizes in the range from 0.1 to about 50 μm. Known pearlescent pigments are used technically, for example, under the brand name Iriodin®. They are used in printing inks, plastic coloring and varnishes, e.g. Car paints, applied. The color effects of these pigments come about through light absorption and interference. Pearlescent pigments of a certain particle thickness meet the interference conditions and show iridescent colors.

According to the invention, Iriodin® 9111 rutile fine satin WR is used to obtain a polymer molding with a very uniform, high-gloss surface and a silver-colored metallic effect. If red Iriodin® 9514 Silkrot WR II is used, after the mold has been removed from the mold, one with a high-gloss, dark red and metal-effect surface is obtained.

In general, pearlescent pigment G or filler F and binder B are used in a ratio of 1: 1 to 20: 1 parts by weight, preferably 2: 1 to 10: 1 parts by weight. In a first approximation, the binders B in question can be divided into polymeric binders (BP) and reactive binder systems (BR) (see H. Wagner & HF Sarx, Lackkunstharze, Carl Hanser Verlag, Munich 1959), which are in the carrier component T are soluble. The polymeric binders B-P can expediently belong to the same polymer class as the cast resins themselves. For example, they are selected from the group of poly (meth) acrylates, in particular polymethyl methacrylate and its copolymers.

In general, the molecular weight Mw of the polymeric binder is in the range 10,000-1,000,000, preferably in the range 100,000-500,000, daltons, the criterion of solubility in the carrier component T being intended to be met. The binder B-P is used in solution in a suitable solvent, preferably in the carrier component T.

The presence of the polymeric binder B-P is not absolutely necessary; on the other hand, at least one reactive binder system B-R is required for curing. These systems can be made from only one reactive binder, e.g. an alkyd resin, e.g. Alkydal® F26, or made up of two or more components that harden under the prevailing conditions. (See H. Wagner, H.F. Sarx, Lackkunstharze loc.cit; Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd. Ed., Vol. 6, pg. 427-445, J. Wiley 1979).

Usable binders can be selected from the class of the polycondensation resins, the polyaddition resins and the polymerization resins. For example, the groups of

- Alkyd resins, in particular oil-modified, for example the oxidized alkyd resins alkyd resins plus diisocyanate alkyd resins plus chlorinated plastics alkyd resins plus polystyrene alkyd resins plus nitrocellulose alkyd resins plus vinyl and epoxy resin alkyd resins plus aminoplasts (plus epoxy resin)

Alkyd resins plus silicone

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Oil modified epoxy resins plus aminoplasts. The oil content can be 20-80% by weight.

- phenoplasts (with or without epoxy, vinyl acetal or aminoplast components)

- Vinyl acetals with or without a phenolic allyl aminoplastic component

- polyester and triazine resins

- Allyl polyester

- Complex amino resins

- Indian and Coumarone resins

For example, Binder B-R formed from e.g. an aromatic polyisocyanate (e.g. commercial products of the DESMODUR® type, products from Bayer AG) and polyesters or polyethers with free hydroxyl groups (for example commercial products of the DESMOPHEN® type from Bayer AG) or those obtained by reacting polyisocyanates with hydroxyl-containing acrylic resins (For example, commercial product JAGOTEX® F232, product from Jäger, factory of chemical raw materials) can be obtained.

For three-dimensional crosslinking, at least one of the reactants must have three or more reactive groups in the molecule.

The lacquers L and optionally L 'can also contain functionalized monomers such as (meth) acrylic acid to improve the adhesive strength in proportions of 0 to 50% by weight, based on the binders BP + BR, and also crosslinking monomers known per se (cf. Rauch- Puntigam, acrylic and methacrylic compounds, Springer-Verlag 1967), for example (meth) acrylic acid esters of polyhydric alcohols (polyols) such as glycol dimethacrylate and others usually in amounts below 15% by weight. Mentioned as binders are e.g. Combinations of binders B-P such as polymethyl methacrylate, optionally with a comonomer fraction - usually <15% by weight - for example methyl acrylate, 2-ethylhexyl (meth) acrylate and the like. with a B-R binder, formed for example from an aromatic polyisocyanate (e.g. commercial product DESMODUR® N 75) and a hydroxyl-containing polyacrylate (commercial product JAGOTEX® F 232). As a guideline for the application, the weight ratio B-P to B-R of (3-1): 1 is given.

The liquid carrier component T in the lacquer L ensures the sprayability in order to evaporate after a certain, appropriately chosen (dry) time. The carrier component T consequently has a boiling point (under normal conditions) in the range 50-220 degrees C, preferably in the range 75-170 degrees C.

(However, the combination of a higher-boiling and a lower-boiling component may also lead to the goal).

The carrier component T can thus advantageously be selected from the group consisting of

- Monomers, especially free-radically polymerizable, for example of the (meth) acrylic acid ester type, in particular with C1-C6-alkyl radicals, very particularly C1 or C2 ester (= T-M)

- Solvents, for example of the (aromatic) hydrocarbon type, the ketones (= T-L)

An additional selection criterion for the carrier component T-L can be an evaporation number (based on ether = 1) of 2-100, especially 2.5-50. The evaporation number (evaporation number) is defined as the time at which a certain amount of solvent (usually 0.3 ml applied to filter paper within 10 seconds from a distance of 10 mm) has evaporated compared to ethyl ether. (See DIN 53 170; Ullmanns Encyclopadie der Techn. Chemie, 4th edition, vol. 1 £, p. 289, V. C. 1978).

Examples of the carrier component T-M are methyl methacrylate, methyl acrylate, ethyl methacrylate, n-butyl methacrylate and the like.

Examples of the carrier component T-L include butyl acetate, ethoxyethyl acetate and the like. and hydrocarbons such as Shellsol®. A combination of T-L + T-M can prove to be advantageous.

The proportion of the carrier component T in the lacquer L is generally in the range 40-90% by weight, the proportion of the polymeric binder B-P is 0-20, preferably 0.5 to 10, in particular 1-10% by weight. The proportion of the pearlescent pigment in the sprayable lacquer L is usually in the range 1-20% by weight, preferably 2-15% by weight.

A typical composition for lacquer L can therefore be:

approx.

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Parts by weight

Methyl methacrylate approx.

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Parts by weight

PMMA

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Pearlescent pigment approx.

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Parts by weight

Alkyd resin, for example Alkydal® F26

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The solvents already mentioned under T, for example butyl acetate, ethyl acetate and / or monomers such as MMA and / or Shellsol® A, are used as solvents for the formulation of the sprayable lacquer Addition of about 1 to 2 parts by weight per 100 parts by weight of sprayable lacquer processes the initiator which triggers the radical polymerization to give the sprayable lacquer.

To produce the lacquer L, for example, one can proceed by dissolving all components except the binder B-R in the carrier component T on the paddle stirrer, then adding the Iriodin® and distributing it intensively with the paddle stirrer. Finally, B-R is added and dissolved.

Casting resins according to the present invention are understood to be liquid, moldable, curable synthetic resins in accordance with the prior art, during the curing of which the polymer moldings are formed. Relevant very well usable casting resins G or corresponding prepolymers can the europ. Patent 218 866 or US-A 4 786 660 or US-A 4 221 697 or US-A 4 251 576. The casting resins G preferably belong to the class of acrylic resins, particularly preferably they are polymers based on methyl methacrylate, a mixture of a prepolymer and the monomers advantageously being used. It is preferably a case of "filled" casting resins containing isto ff, in particular highly filled casting resins, especially those in which the fillers make up a proportion of 50-80% by weight, based on the casting resin.

Suitable fillers F are the finely divided inorganic or organic materials used for casting resins. An average grain size of 100 μm diameter is expediently not exceeded. Granular particles are preferred. Occasionally, it can be advantageous to free the particles from adsorptively bound moisture by heating, for example to 250 degrees C. The fillers F can be natural products or synthetically produced. The mechanical properties such as hardness, elastic shear modulus are based on the intended application of the casting resin. The setting of an elastic shear modulus of at least 5 GNm-2 can be advantageous. Suitable are e.g. Minerals such as aluminum oxides, aluminum hydroxides and derivatives e.g. Alkali and alkaline earth double oxides and alkaline earth hydroxides, clays, silicon dioxide in its various modifications, silicates, aluminosilicates, carbonates, phosphates, sulfates, sulfides, oxides, coal, metals and metal alloys. Synthetic materials such as glass powder, ceramics, porcelain, slag and finely divided synthetic SÌO2 are also suitable. Silica modifications such as quartz (quartz powder), tridymite and cristobalite, as well as kaolin, talc, mica, feldspar, apatite, baryte, gypsum, chalk, limestone, dolomite may be mentioned. If necessary, mixtures of fillers can also be used. The proportion of filler in the casting resins is generally at least 20% by weight. In general, a proportion of 80% by weight is not exceeded. A filling content of the casting resin of 50-80% by weight is given as a guideline. The fillers in the appropriate grain sizes can be produced by the known processes, e.g. by breaking and grinding. Cristobalite and aluminum hydroxide are particularly preferred.

The implementation of the method according to the invention requires the usual molding tools and spraying devices. The modalities of the order can advantageously be demonstrated on a metal plate (for example on a nickel-plated, highly polished brass plate). The temperature of choice for the metal surfaces to be applied is 85 degrees C. We recommend warming up for about 30 minutes beforehand, for example in a drying cabinet at this temperature.

The application can be carried out with a suitable spray gun (e.g. brand SATA Minijet), for example with a 0.8 mm nozzle and a pressure of 2.5 bar. The individual lacquer layers are advantageously produced by spraying lacquers L 'and L twice over the entire surface of the metal plate. The painting time is generally 2-2.5 minutes. Immediately after the last painting, the object is again placed in the heating chamber (drying cabinet) at 85 degrees C. In a short time, for example less than 5 minutes, the casting resin G is then expediently filled. The procedure is based on a filler-containing PMMA / MMA cast resin explained in more detail. For example, a mold is made within approx. 3 minutes from the metal plate provided with the paint, a suitable second, unpainted metal plate (as a stop 350 x 350 x 4 mm) and a sealing cord (e.g. PVC cord with a diameter of 4 mm) Chamber in which the highly filled, optionally colored (degassed) casting resin with, for example, PMMA / MMA as the curable synthetic resin and with at least one initiator which triggers the free-radical polymerization, for example a perester such as bis- (4-tert.butylcyclohexyl) peroxydicarbonate, is customary Quantities (eg 0.5-5 wt .-% based on the monomers) filled in a short time, for example about 1.5 minutes. After the mold chamber has been closed, it is first carried out at elevated temperature - for example at approx. 65 degrees C and in a water bath, with the mold chamber in a horizontal position and advantageously with the lacquered side down - for a period of - as a stop - 20 minutes and then at still higher temperature, for example at 105 degrees C, preferably annealed in a drying cabinet for 15 minutes. The polymer molding is then removed from the molding chamber at about 60 to 70 degrees C.

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Beneficial effects

According to the process of the invention, new polymer moldings made from cast resins with a metallic glossy, optionally colored and very uniform surface metal effect are obtained. They also show long-term storage in water - test: 24 hours in 90 ° C hot water - no superficial whitening, the so-called "water whitening" effect.

The following examples and information on the production of the molded polymer parts serve to illustrate the invention.

EXAMPLES

A) Preparation of the spray paint L Example 1:

5.0 parts by weight of a polymethyl methacrylate with a content of 10% by weight of methyl acrylate (Mw = approx. 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 from BAYER AG) are added to this solution and dissolved. 20 parts by weight of Iriodin® 9111 rutile fine satin WR (Merck) are added to this syrup while stirring with a paddle stirrer. The stirring time is approx. 30 minutes. 12.5 parts by weight of Shellsol® A (Shell), 12.5 parts by weight of n-butyl acetate and 1 part by weight of Interox® BCHPC = bis- (4 -t-butylcyclohexyl) peroxidicarbonate, from Peroxid-Chemie GmbH, added and dissolved.

Example 2:

Procedure as in Example 1, instead of Iriodin® 9111 rutile fine satin WR, the same amount of Iriodin® 9514 Silkrot WRII was used.

B) Production of 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% by weight of methyl acrylate (Mw = approx. 350,000) and 45 parts by weight of silanized cristobalite (product SILBOND® 6000 MST the quartz movement Frechen) dispersed on the dissolver at approx. 10.0 m / sec for 15 minutes. 1 part by weight of glycol dimethacrylate and 3 parts by weight of Alkydal® F26 (60% in xylene, a product from BAYER AG) are added to this suspension and dissolved.

To 50 parts by weight of this cristobalite-containing lacquer are added 12.5 parts by weight of Shellsol® A (Shell), 12.5 parts by weight of n-butyl acetate and 1 part by weight of Interox® BCHPC = bis- (4th -t-butylcyclohexyl) peroxidicarbonate, from Peroxid-Chemie GmbH, added and dissolved.

C) The highly filled casting resin

To a prepolymeric pre-solution, e.g. 40 parts by weight of a solution of NMA / PMMA (weight ratio 35: 5), which also contains crosslinking agents and, if appropriate, a silane with a silanization catalyst, 50-80 parts by weight of an inorganic filler are dispersed. Cristobalite or aluminum hydroxide are preferably used. In addition to mold release agents such as stearic acid, the casting resin also contains a polymerization initiator such as Bis- (4-tert.butylcyclohexyl) peroxydicarbonate or a common redox system.

D) Production of the polymer moldings

The production of the polymer moldings is described in more detail above in the section on carrying out the process.

E) Checking the molded parts for water whitening

Test specimens of 50 x 50 mm are cut from the plate castings. The test specimens are stored in water at a temperature of 90 degrees C for 24 hours. After a further storage period of 24 hours at room temperature in air, the samples are compared with a delivery sample.

Result:

The shaped pieces according to the invention show after the water treatment compared to the delivery 6

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practically no brightening. Hardened cast resins without a pearlescent pigment coating show a noticeable brightening after the “water whitening” test.

Claims (10)

Claims 1. Polymer moldings made of highly filled casting resins with shiny metallic surfaces, characterized in that the shiny metallic surface is a feed containing pearlescent pigment. 2. Polymer moldings according to claim 1, characterized in that the shiny metallic surface is formed with a colored pearlescent pigment. 3. Polymer moldings according to claim 1 or 2, characterized in that the casting resin contains PMMA / MMA as a hardenable synthetic resin. 4. A process for the production of polymer moldings from highly filled casting resins with shiny metallic surfaces, according to one of claims 1 to 3, characterized in that a surface of the shaping tool before filling with the casting resin with a hardenable coating of a pearlescent pigment-containing lacquer composition L is coated, and after the paint layer has dried, the tool is filled with the casting resin and polymerized with heating and finally removed from the mold. 5. The method according to claim 4, characterized in that in a first painting step, a lacquer L 'without pearlescent pigment addition, but containing filler is applied and after drying the lacquer L is applied as in claim 4, the tool is filled with the casting resin and polymerized with heating and finally removed from the mold. 6. The method according to claim 4 or 5, characterized in that the lacquer contains, in addition to the pearlescent pigment, binder B and at least one liquid carrier component T. 7. The method according to claim 6, characterized in that the binders B in addition to the hardening system B-R also consist of a polymeric binder B-P. 8. The method according to claim 7, characterized in that the polymeric binder B-P is a homo- or copolymer of methyl methacrylate. 9. The method according to claim 6, characterized in that the liquid carrier component T has a boiling point under normal conditions in the range 50-200 degrees C. 10. The method according to any one of claims 6 to 9, characterized in that the carrier component T consists entirely or partially of free-radically polymerizable monomers. 7