DE2650340A1 - PLASTICS SHOWING WHITE IN VISIBILITY - Google Patents

Description

Bayer Aktiengesellschaft

Central area of patents, trademarks and licenses

. "." .- ■ 5090 Leverkusen, Bayerwerk

Hö / bc

12. No *. 1976

Plastics that appear white when viewed from above and through

The invention relates to plastics that appear white when viewed from above and through. In particular, it concerns such Plastics whose optical behavior (such as remission, transmission, cloudiness and color cast) is decisive for the Application is. It is based on translucent polymers such as polyacrylate, Polymethacrylate, polycarbonate, polystyrene, polyester or cellulose ester, which are mixed with white pigments such as titanium phosphate, Lead hydrogen phosphate, zinc oxide, zinc sulfide, magnesium titanate, Calcium titanate, anatase or rutile can be colored.

So far, it has been assumed in the production of white translucent plastic that the particle size of the pigments should be in a narrow distribution around a value d, which was already given by Mie in 1905,

(m ² + 2).

——5— ■ in to

(m ² - 1) '

compare also van de Hülst, "Light scattering by small particles", John Wiley and Sons, New York / London 1957, provided that the maximum of the scattering coefficient at the wavelength j, "." ή 420 mm,

ItIaX

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whereby

η the refractive index of the polymer η the refractive index of the pigment and

m = - is.
η
ο

In the German Offenlegungsschrift 2 314 253 particularly finely divided titanium dioxides claimed to improve opalescence. About the purity and the shine To not impair the opalescent materials, a titanium dioxide pigment should be used that does not contain particles larger than 0.15 µm in diameter. It is also state of the art, rutile crystals with an average volume diameter of about 0.05 to 0.10 μm and with the narrowest possible particle size distribution to use with possibly the addition of further transparent phthalccyanine blue pigments or quinacridone red pigments.

This reference is consistent with the am TiO ^ types on the market for coloring plastics, which are optimized towards the finely divided side.

Disadvantages of these finely divided titanium dioxides, in particular in a Texlchendurchmesser of less than 0.15, to have increased by the high specific surface photoactivity ι their often insufficient dispersibility and their insufficient color neutrality in reflected and transmitted vision ^

Surprisingly, it has been found that coarse-grained white pigments Plastics containing not only a high level of haze, they also have an appearance when viewed from above and through comes very close to the desired neutral white. The subject of the invention are therefore in inspection and review Containing white plastics appearing neutral in color

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a translucent polymer and a white pigment having an average part ohmic diameter d and a refractive index des'Pigmentes η is greater than 1.65, preferably 1.7 to 2.9, and the mean particle diameter d between 1.2 d and 6 d, where

d = <^ 22
° ⁿ o (m ² - 1) /

η = refractive index of the polymer. In a particularly preferred one Range is d between 2 d and 5 d.

The advantage of the plastic according to the invention is when desired Light scattering and light transmission of the white neutral color in front and through.

It has also been shown that it has not been predominantly assumed, as previously, as narrowly as possible Particle size distribution matters, but pigments with a broad particle size distribution also have the desired properties of plastics produce, as far as the refractive index and the mean particle diameter in the invention Area lie.

According to DIN 53206.1, the value d can be the light scattering equivalent diameter are designated. In this application the mean pigment particle diameter is d either Determined by electron microscopy or by the BET method, with particle diameters of more than 1 .mu.m being preferred the BET method is used. It is therefore the projection or surface equivalent diameter. These two values differ little from one another, especially in the case of calcined pigments, so that depending on the mean value Particle diameter and surface properties of the pigment of one of the two methods according to the state of the art the technology is used. According to the invention, the projection or surface equivalent just mentioned should

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Diameter are at least 20%, preferably 50 to 600%, above the light scattering equivalent diameter. A particularly preferred range is between 2 d and 5 d.

Suitable pigments for the purposes of the invention have a refractive index above 1.65. For example: magnesium aluminum oxide, aluminum oxide, lead phosphate, lead hydrogen phosphate, titanium phosphate, aluminum titanate, tin oxide, zinc oxide, antimony oxide, zirconium oxide, zinc sulfide, zinc titanate, magnesium titanate as MgTiO ₃ , Mg ₃ TiO ₄ , MgTi ₃ O ₅ , calcium titanate and titanium dioxide or rutile, each alone or mixed. The decisive factor is the mean particle size, which should be at least 20% above the value d. The pigments are produced by known precipitation and / or calcination processes. By using higher calcination temperatures, the particles become coarser, and in some cases the particle size distribution is broadened as a result, but according to the invention this has no negative influence on the coloring of plastic.

The amount of pigment required in the plastic depends on various parameters. Pigment and polymer are within the meaning of the invention not independent of one another. As can be derived theoretically, falls for the Coarse-particle pigments to be used according to the invention, the scattering power with the particle size, so that the The amount of pigment must be greater for coarser particles,

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265Q340

if the turbidity of the colored polymer should remain constant. The refractive index of the polymer and the pigment goes into the particle size, which Mie has already derived. For example, are approximate for polymers with a refractive index η of about 1.59, the following amounts of pigment are necessary if the same haze is achieved should be the same as with an addition of 0.01% rutile:

Anatase 0.012%, zinc sulfide 0.015-0.02%, zinc oxide 0.04 to 0.06%, lead hydrogen phosphate 0.1 to 0.2%.

In practice, depending on the desired light transmission For example, rutile pigments between 0.001 and 1% by weight are added to the plastic. There have to be larger quantities of the pigments according to the invention are used than comparable ones finely divided pigments, if scattering, turbidity, Light transmission should remain unchanged. The level of pigmentation also depends on the wall thickness of the plastic. Shaped bodies with a wall thickness of several millimeters must be pigmented less than a few micrometers thick Films when remission and transparency should be comparable. The visual effect, especially the neutral one The white color of the pigmented plastics hardly depends on the concentration, but only on the particle diameter the pigments.

Plastics within the meaning of the invention are transparent, transparent as well as translucent thermoplastic and duroplastic Polymers such as polycarbonate, polyethylene, Polystyrene: polyacrylate, polymethacrylate and their copolymers, as well as cellulose esters and polyesters.

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Polycarbonates in the context of the invention come from the reaction of diphenols, in particular dihydroxydiarylalkanes / with phosgene or diesters of carbonic acid available polycondensates into consideration, the unsubstituted Dihydroxydiarylalkanes are also suitable whose aryl radicals are in the o- and / or m-position to the hydroxyl group Carry methyl groups or halogen atoms. Branched polycarbonates are also suitable.

Polycarbonates have average weight average molecular weights Mw between 10 OOQ and 100,000, preferably between 20,000 and 40,000, determined by measurements of the rel. Viscosity in CH ₂ <
concentration of 0.5% by weight.

the rel. Viscosity in CH ₂ Cl ₂ "at 25 ° C and a con-

Suitable diphenols are, for example, hydroquinone, resorcinol _t 4,4 ^t -dihydroxydiphenyl, bis (hydroxyphenyl) alkanes such as C ₁ -C 6 alkylene or C ₂ -Co alkylidenebisphenols, bis (hydroxyphenyl) cycloalkanes such as Cr-C ^ c cycloalkylene or Cc-Cr cycloalkylidene bisphenols, bis (hydroxyphenyl) sulfides, ethers, ketones, sulfoxides or sulfones. Furthermore oi. " jL * "bis (hydroxyphenyl) diisopropylbenzene and the corresponding nucleus alkylated or nucleus halogenated compounds. Preference is given to polycarbonates based on bis (4-hydroxyphenyl) propane-2, 2 (bisphenol A), bis (4-hydroxy-3, 5-dichlorophenyl) -propane-2,2 (tetrachlorobisphenol A \, bis- (4-hydroxy-3,5-dibromophenyl) -propane-2,2 (tetrabromobispfeenol A), bis- (4-hydroxy- 3,5-dimethyl-pheny1) -propane-2,2

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(Tetramethylbisphenol A), bis- (4-hydroxyphenyl) -cyclohexane-1,1 (bisphenol Z) and based on three-ring bisphenols such as jL /, ^ L ¹ -bis- (4-hydroxyphenyl) -p-diisopropylbenzene.

Further diphenols suitable for the production of polycarbonate are described in US Patents 2,970,131, 2,991,273,

2 999 835, 2 999 846, 3 014 891, 3 028 365, 3 062 781,

3 148 172, 3 271 367, 3 271 368 and 3 280 078.

Suitable polystyrenes are homopolymers of styrene or copolymers of styrene with, preferably, acrylonitrile and / or butadiene, and / or maleic acid ester, which e.g. by suspension polymerization in the presence of catalysts from the monomers or the mixture of monomers with Mw of 10,000-600,000 (Mw is measured in DMF at c = 5 g / l and 20 ° C).

(For literature see: Beilstein's Handbook of Organic Chemistry, fourth edition, third supplementary work, volume 5, Pages 1163-1169, Springer Verlag 1964, H. Ohlinger, Polystyrene, part 1, manufacturing process and properties der products, Springer Verlag 1955).

Cellulose esters for the purposes of the invention are conventionally Process by esterification of cellulose with aliphatic monocarboxylic anhydrides, preferably acetic acid and Butyric or acetic and propionic anhydride, won. The hydrolysis to be carried out in the raw solution is controlled by a small excess of water so that

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that a low hydroxyl content (4 to 25) is obtained. The oxidative bleaching of the cellulose ester isolated from the solution must be carried out in such a way that in the end product no more oxidizing agent can be detected; Post-treatment with reducing agents may be necessary take place.

The free hydroxyl groups are used to determine the OH number of the cellulose ester esterified with acetic anhydride in pyridine, the excess anhydride reacted with water and back-titrated / regulation: CJ- Mahn, L.B. Genung and R.F. Williams, Analysis of Cellulose Derivatives, Industrial and Engineering Chemistry, Vol. 14, No. 12, 935-940 (1942) 7.

The viscosity of the cellulose ester should be 0.3 to 0.5 poise, measured as a 20% strength by weight solution in acetone. Cellulose esters to be used preferably have an acetic acid content of 17 in the case of the acetobutyrates up to 23% by weight and a butyric acid content of 45 to% by weight, in the case of the acetopropionates a propionic acid content of 61 to 69% by weight and an acetic acid content of 2 to 7% by weight. The OH numbers are usually between 4 and 25. The weight average molecular weights Mw are between 10,000 and 1,000,000, preferably between 100,000 and 500,000.

Polyalkylene glycol terephthalates in the context of the present invention are, for example, those based on ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and 1,4-

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Bis-hydroxy-methylcyclohexane. The molecular weights (M) of these polyalkylene glycol terephthalates are between 1,000 and 80,000. The polyalkylene glycol terephthalates can be prepared, for example, from dialkyl terephthalate and the corresponding diol by known processes can be obtained by transesterification (see e.g. U.S. Patents 2,647,885, 2,643,989, 2,534,028, 2,578,660, 2,742,494, 2 901 466).

For example, one starts from a lower alkyl ester of terephthalic acid, preferably the dimethyl ester, and esterifies this with an excess of diol in the presence of suitable catalysts to give the bishydroxyalkyl ester of terephthalic acid. The temperature is raised from 14O ⁰ C to 21 & to 220 ⁰ C. The alcohol released is distilled off. The condensation then takes place at temperatures of 210 to 280 ° C., the pressure being reduced in stages to less than 1 torr, the excess diol being distilled off.

Polyacrylates and polymethacrylates which can be colored with the pigments according to the invention are Homo- and copolymers of acrylic acid ester and methacrylic acid ester with molecular weights of 10 to 10 and with 4 to 18 carbon atoms in the monomer unit such as e.g. Isobutyl polyacrylate, methyl polymethacrylate, Ethylhexyl polymethacrylate, ethyl polyacrylate, Copolymers from various acrylic

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acid esters and / or methacrylic acid esters such as methacrylic acid methyl ester-acrylic acid cyclohexyl ester copolymers, also copolymers of acrylic acid esters and / or methacrylic acid esters with crosslinkers such as 1,4-butanediol dimethacrylate, Glycol dimethacrylate, triglycol dimethacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, triallyl cyanurate, also copolymers of acrylic acid esters and / or methacrylic acid esters with styrene and / or ot -Methylstyrene, as well as those from acrylic esters, methacrylic acid esters, Graft polymers and mixed polymers and polymer blends composed of styrene and butanediene.

Olefin homopolymers and copolymers within the meaning of the present Invention are mainly the poly -. ^ .- olefins with 2 to 10 carbon atoms in the monomer unit, such as high and low pressure polyethylene, polypropylene, poly-1-butene, Polyisobutylene, poly-1-pentene or poly-4-methyl-1-pentene, Copolymers of different ^ -olefins, such as ethylene-propylene copolymers or terpolymers, also homo- and copolymers of conjugated aliphatic dienes, such as polybutadiene, polyisoprene, Polychloroprene, styrene-butadiene and acrylonitrile-butadiene copolymers as well as those made from acrylonitrile and butadiene and styrene composite copolymers and graft polymers and polymer blends and copolymers of tf — olefins copolymerizable with others, olefinic unsaturated compounds, such as ethylene vinyl chloride, Ethylene-vinyl acetate or ethylene-acrylic acid copolymers.

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The polyester resin compounds contain * _, ß-ethylenically unsaturated Polyester and vinyl or vinylidene compounds copolymerizable therewith underlying.

Such. <_, Ssäthylenisch unsaturated polyesters are the polycondensation products of at least one customary oC, ßäthylenisch unsaturated dicarboxylic acid having usually 4 or 5 carbon atoms or their derivatives esterbildenden ^ optionally in admixture with up to 90 mol%, based on the unsaturated acid components, at least one aliphatic saturated with 4-10 carbon atoms or a cycloaliphatic dicarboxylic acid with 8-10 carbon atoms or their ester-forming derivatives with at least one polyhydroxy compound, in particular dihydroxy compound, with 2-8 carbon atoms - i.e. polyesters, such as, for example at JR Lawrence, "Polyester Resins", Reinhold Publ. Corp., New York 1960, pp. 18 f., 'and Goerden-Vieweg Kunststoff-Handbuch, Vol. VIII ("Polyester"), Carl Hanser Verlag, Munich 1973, Pp. 247-312.

Examples of unsaturated dicarboxylic acids to be used with preference or their derivatives are maleic acid or maleic anhydride and fumaric acid. Can be used e.g. but also mesaconic acid, citraconic acid, itaconic acid or chloromaleic acid. Examples of the aliphatic to be used saturated and cyclo-aliphatic dicarboxylic acids or their derivatives are phthalic acid or phthalic anhydride, isophthalic acid, terephthalic acid, hexa- or tetrahydrophthalic acid or their anhydrides, endomethylenetetrahydrophthalic acid or their anhydride, succinic acid or succinic anhydride and succinic acid esters and chlorides, adipic acid, Sebacic acid. To make flame retardant resins, e.g. hexachlorendomethylenetetrahydrophthalic acid (hetic acid), tetrachlorophthalic acid or tetrabromophthalic acid be used. Preferred polyesters to be used contain maleic acid residues ranging from 25 mol% to 75 mol%

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be replaced by phthalic or isophthalic esters can. As dihydric alcohols, ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene- glycol, thiodiglycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 2,2-bis (4-hydroxycyclohexyl) propane, bis-oxalkylated bisphenol A, perhydrobisphenol and others are used. Ethylene glycol, 1,2-propanediol, diethylene glycol and dipropylene glycol are preferably used.

Further modifications are possible by incorporating up to mol%, based on the alcohol or acid component, including, tri and tetravalent alcohols with 1-6 carbon atoms, such as methanol, ethanol, butanol, allyl alcohol, benzyl alcohol, Cyclohexanol and Tetrahydrofurfury! Alcohol, trimethylolpropane, Glycerine and pentaerythritol as well as mono-, di- and triallyl ethers and benzyl ethers trivalent and polyvalent Alcohols with 3-6 carbon atoms according to DT-AS 1 024 654, as well as by incorporating monobasic acids such as benzoic acid, or long-chain unsaturated fatty acids such as oleic acid, linseed oil fatty acid and ricinic fatty acid.

The acid numbers of the polyesters should be between 1 and 100, preferably between 20 and 70, the OH numbers between 10 and 150, preferably between 20 and 100, and the as Molecular weights M measured in cash between approx. 500 and 5000, preferably between approx. 1000 and 3000 are Cdampfdruckosmometrisch measured in dioxene and acetone; if the values differ, the lower considered the correct one).

Suitable copolymerizable vinyl and vinylidene compounds in polyester technology are those customary

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unsaturated compounds, which are preferably λ, -substituted Carry vinyl groups or ß-substituted allyl groups, preferably styrene; but also, for example, nuclear chlorinated and -alkylated or -alkenylated styrenes, where the alkyl groups can contain 1-4 carbon atoms, such as vinyl toluene, divinylbenzene c <_- methyl styrene, tert-butyl styrene, Chlorostyrenes; Vinyl esters of carboxylic acids with 2-6 carbon atoms, preferably vinyl acetate; Vinyl pyridine, Vinylnaphthalene, vinylcyclohexane, acrylic acid and methacrylic acid and / or their esters (preferably vinyl, AlIyI- and metalallyl ester) with 1 - 4 carbon atoms in the alcohol component, their amides and nitriles, maleic anhydride, half and diesters with 1-4 carbon atoms in the alcohol component, half and diamines or cyclic imides such as N-methyl maleimide or N-cyclohexyl maleimide; Allyl compounds such as allylbenzene and allyl esters such as allyl acetate, diallyl phthalate, diallyl isophthalate, Diallyl fumarate, allyl carbonates, diallyl carbonates, Triallyl phosphate and triallyl cyanurate.

The polyester casting resins usually contain 30-75 parts by weight Polyester and 70-250 parts by weight of copolymerizable vinyl or vinylidene compounds.

Corrections can be made in the case of color-tinged polymer material may be required by adding known dyes and / or optical brighteners.

The processing of the pigmented plastics and the use of auxiliaries are made according to the invention coarser pigments are not affected. Possible auxiliaries are fillers - such as, for example Calcium carbonate, quartz powder, barium sulfate,

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Kaolins - thermal stabilizers, UV absorbers, optical brighteners, lubricants, waxes, plasticizers, flame retardants or light stabilizers. The plastic can be extruded or injection molded on commercially available machines or rolled.

A measure for the objective optical assessment of the invention Plastics is the yellowness index (ASTM D 1925-70). In the examples described below test specimens with a haze of approx. 80% were produced in each case (ASTM 1003). The determination of the transmission degree for light that was just transmitted (light type C DIN 5033) was carried out with the Zeiss spectrophotometer PM Q II. The amount of the yellowness index should be less than 20 for plastics colored according to the invention be.

Polymers provided with coarse pigments and having a yellowness index of less are preferred than 10, values between +5 and -5 are particularly desirable

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example 1

Polycarbonate granules with a low color number were mixed with 0.013% by weight of a coarse TiO ^ white pigment produced by annealing at high temperatures and extruded. The rutile pigment had a central value of the volume distribution D ". _rr according to DIN 53206 of 0.37 μm and one

uVil /

Particle size distribution width 6 "g of 1.35. The specific

The BET surface area was 4.8 m / g. The colored one With a wall thickness of 4 mm, test specimens had a transparency of about 40-50% and appeared in top view and Color-neutral view. The measurement gave a yellowness index of 6.

Example 2

According to Example 1, a test specimen made of polycarbonate was made produced with the same haze, transparency and wall thickness using 0.03% of a coarse-grained Rutile pigment with a mean value of the volume distribution D of 0.78 μm and a £ g value

of 1.47. The specific surface was 2.7 m / g, the yellowness index of the test specimen was determined to be -16. The test specimen appeared in supervision and Almost neutral in color.

Example 3

In accordance with Example 1, a commercially available rutile pigment was used for plastics that are burned after TiCl ^ combustion procedure was established, used.

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The D ". ₇ value was 0.26 µm, the £ yg value 1.53

"VJj / ^

and the specific surface area at 8.2 m / g. The test specimen pigmented with 0.011% TiO 2 showed at 4 mm Wall thickness had a yellowness index of 88 and the transmitted light appeared clearly yellow to the eye to orange. Example 3, like example 4, is used for comparison.

Example 4

One based on the sulfate process for plastic pigmentation commercially available rutile pigment produced with

2 a specific surface of 7.4 m / g and a D “ _T. -Value of 0.23 µm with an Ög-value of 1.44

Ct VJj /

incorporated into polycarbonate according to Example 1. At a pigmentation level of 0.011% by weight appeared the test specimen had a yellowish tinge when viewed through and resulted in a yellowness index of 99.

Example 5

A TiO ₂ mixed pigment made from rutile and anatase with a

O “ _Trr value of 0.43 µm, a β'g value of 1.49 and

/ 2

With a specific surface area of 4.9 m / g, 0.03% was incorporated into polycarbonate as in Example 1 and measured. The sample was neutral in color when viewed from above and through and had a yellowness index from -3 to.

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Example 6

A pigment mixture of the titanium dioxides used in Examples 1 and 2 was produced according to Example 1 incorporated. The mixture contained 1 part by weight of the pigment from Example 1 and 10 parts by weight of the pigment from Example 2. With a pigmentation level of 0.025%, the result was a yellowness index of Test body from -3. The test specimen appeared neutral in color when viewed from above and through. The pigment mixture had a D value of 0.73 µm and a value of 6 g

/ 2

of 1.68. The specific surface area became 3.6 m / g

certainly.
Example 7

A polycarbonate granulate with a low color number was made with 0.1% by weight of a coarse zinc oxide white pigment mixed and extruded. The ZnO pigment had one

specific surface of 0.8 m / g. According to references (F. Kindervater DFZ. J_3, 312 (1959)) From this, calculate an average particle diameter for spherical particles using the following formula d = ——

BET §

The mean particle diameter d in µm results

2 then from the BET surface area in m / g and the density of ZnO at 5.6 g / cm with d = 1.34 µm.

The test specimen with a wall thickness of 4 mm was examined in accordance with the previous examples. It appeared neutral in color in supervision and review, the yellowness index was determined to be 12.

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Example 8

For comparison, a polycarbonate was colored with 0.3% by weight of a finely divided polycarbonate not according to the invention ZnO pigment with a BET specific surface area of 3.6 m / g, corresponding to an average particle diameter from 0.30 to. With a wall thickness of the test specimen of 1 mm and thus approximately the same turbidity resulted a yellowness index of HO and a clear yellow coloration of the transmitted light.

Example 9

_{O r} 06% by weight of the coarse-particle titanium dioxide pigment used in Example 2 was added to a polyester casting resin, cast to give 4 mm thick test plates and cured at 90 ° C. for 15 hours. The measurement showed a yellowness index of -8 with somewhat higher haze values.

Example 10

The pigmentation of a polyester casting resin according to Example 9 was _{repeated for comparison with the commercially available Ti0 2} ~ pigment from Example 4, 0.03% by weight being added. The yellowness index determined on the 4 mm thick test specimen was measured as 74. The polyester plate mixed with the coarser pigment to be used according to the invention had a considerably more color-neutral appearance

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and the light that passed through appeared significantly less yellowish than when pigmented with the TiO ₂ pigments commercially available for plastics. the
Turbidity values of the test specimens according to Examples 9 and 10
were of roughly the same order of magnitude.

Example IT

Granules of a cellulose ester with a low color number were mixed with 0.013% by weight of a titanium dioxide pigment customary for plastic pigmentation and used in Example 4 , extruded and processed to give 3 mm thick test specimens. When viewed through, the test specimen appeared yellowish and had a yellowness index of 90.

Example 12

Test specimens were used as in Example 1T of 0.027% by weight of the coarse particles used in Example 6 Pigment mixture prepared and tested. The 3 mm thick test specimen appeared from above and through color neutral. The yellowness index of the test specimen was T.

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Claims (8)

Claims 1) Plastic that appears white when viewed from above and through,
Containing a translucent polymer and a white pigment with an average particle diameter d and the refractive index n, characterized in that the refractive index of the pigment η is greater than 1.65, preferably 1.7 to 2.9 and the average particle diameter d is between 1.2 d and 6 d _Q , where 2
_{d =} in _{/ U} m, with m = - and ° ⁿ o On - 1) ' ⁿ o η = refractive index of the polymer. 2) white translucent plastic according to claim 1, characterized in that it contains fillers in addition to the white pigment, Contains optical brighteners, stabilizers, plasticizers and / or other auxiliaries. 3) white translucent plastic according to claim 1, and 2, characterized in that the white pigment in amounts between O, OO1 and 20 wt .-%, preferably between
0.005 and 5% by weight, based on the polymer content,
is used. 4) White translucent plastics according to claim Ibis
3, characterized in that the white pigment is titanium phosphate, lead hydrogen phosphate, zinc oxide, zinc sulfide, magnesium titanate, calcium titanate, anatase or rutile
can be used individually or as a mixture. 5) White translucent plastics according to claim 1 to 4 characterized in that the polymer, polyacrylate, polymethacrylate, polycarbonate, polystyrene, polyethylene, Is polyester or cellulose ester. Le A 17 436 - 20 - 809819/020 6 265034Q 6) white translucent plastic according to claim 1, characterized characterized in that it is based on polycarbonate 0.001 to 1% titanium dioxide with an average particle diameter between 0.40 and 0.80 µm. 7) white translucent plastic according to claim 6, characterized in that the titanium dioxide pigment Anatase modification and a BET specific surface area of less than 5.5, preferably 0.5 to 2
Contains 4.5 m / g. 8) white translucent plastic according to claim 6, characterized in that it has a rutile pigment a specific surface area of less than 5.5, 2
preferably contains 0.5 to 4.5 m / g. Le A 17 436 - 21 - 809819/0206