Use of a plastic dispersion as coating for inorganic and organic particles

Abstract: The invention relates to the use of a plastic dispersion as coating for inorganic and organic particles, such as pigment particles and colourant particles. The plastic dispersion is a dispersion of a polymer based on a. a vinyl monomer, b. (C₁-C₁₂) alkyl(meth)acrylate, (C₁-C₁₂) dialkylitaconate, (C₁-C₁₂) dialkylfumarate and/or (C₁-C₁₂) dialkylmaleate, c. a monomer containing sulphonic acid groups, or a corresponding salt of it, and d. 0-0.3% (wt) organic unsaturated mono- and/or dicarboxylic acid.

Description: The invention relates to the use of a plastic dispersion as coating for inorganic and organic particles, such as pigment particles and colourant particles. The use of plastic dispersions as coatings for inorganic and organic particles, such as pigment particles and colourant particles, is described on page 165 of the Pigment Handbook (Volume III, by Temple C. Patton, 1973). Such pigment particles or colourant particles coated with plastic dispersions can be mixed into various plastics. After mixing with plastics, such coated pigment particles often cause problems owing to the formation of agglomerates. In general the coated pigment particles are suited only for mixing with highly specific plastics. That is why plastic dispersions are sought resulting in a good homogeneous distribution of pigments and colourants in a plurality of plastics without agglomerates being formed. The invention is characterized in that the plastic dispersion is a dispersion of a polymer based on (a) 50-99% (wt) vinyl monomer, (b) 0.50% (wt) (C 1 -C 12 ) alkyl(meth)acrylate, (C 1 -C 12 ) dialkylitaconate, (C 1 -C 12 ) dialkylfumarate and/or (C 1 -C 12 ) dialkylmaleate, (c) 0,1-5% (wt) monomer containing sulphonic acid groups, and/or a corresponding salt of it, and (d) 0-0.3% (wt) organic unsaturated mono and/or dicarboxylic acid. The result is that pigment particles and colourant particles coated with the plastic dispersion are obtained that can be mixed with many different types of plastics without resulting in the formation of agglomerates. According to a preferred embodiment the plastic dispersion is a dispersion of a polymer based on (a) 50-99% (wt) vinylaromatic monomer, (b) 0-50% (wt) (C 1 -C 12 ) alkyl(meth)acrylate, (C 1 -C 12 ) dialkylitaconate, (C 1 -C 12 ) dialkylfumarate and/or (C 1 -C 12 ) dialkylmaleate (c) 0.1-5% (wt) sulpho (C 1 -C 12 ) alkyl(meth)acrylate, or a salt of it, and (d) 0-0.3% (wt) unsaturated mono and/or dicarboxylic acid. The vinyl monomer can, for instance, be a vinylaromatic monomer, vinylacetate, vinylversatate, vinylaurate or vinylcaprate. Preference is given to the use of a vinylaromatic monomer such as, for instance, styrene. Other suitable vinylaromatic monomers include for instance vinyltoluene and methylstyrene. The preferred component (b) is (C 1 -C 12 )alkyl(meth)acrylate. (C 1 -C 12 ) alkyl(meth)acrylate is preferably methyl(meth)acrylate. Other suitable (C 1 -C 12 ) alkyl(meth)acrylates include, for instance, ethyl(meth)acrylate, butyl(meth)acrylate and 2-ethyl-hexyl(meth)acrylate. According to a preferred embodiment of the invention, the percentage by weight of organic unsaturated mono- and/or dicarboxylic acid is substantially 0% (wt). If organic unsaturated mono or dicarboxylic acid is present, it is preferably (meth)acrylic acid. Monomers containing suitable sulphonic acid groups include, for instance, sulpho (C 1 -C 12 ) alkyl(meth)acrylates, sulpho (C 1 -C 12 ) dialkylmaleates, sulpho (C 1 -C 12 ) dialkylfumarates, sulpho (C 1 -C 12 ) alkylitaconates, sodiumvinylsulphonate, styrenesulphonate and/or acrylamidoalkanesulphonic acid. The salts applied are preferably ammonium, potassium, sodium or amine salts. Sulpho(C 1 -C 12 ) alkyl(meth)acrylates are preferably used as component (c). As sulpho (C 1 -C 12 ) alkyl(meth)acrylate, sulphopropyl(meth)acrylate and/or sulphoethyl(meth)acrylate are preferably used. Suitable sulpho(C 1 -C 12 )alkyl(meth)acrylates include, but are not limited 2-sulpho-α-ethylacrylate, 2-sulpho-α-propylacrylate, 2-sulphoethyl-α-butylacrylate, 2-sulphoethyl-α-hexylacrylate, 2-sulphoethyl-α-cyclohexylacrylate, 2-sulpho-α-chloroloroacrylate, 1-sulpho-2-propyl(meth)acrylate, 2-sulpho-1-butyl(meth)acrylate, 1-sulpho-2-butyl(meth)acrylate, 3-sulpho-2-butyl(meth)acrylate, 2-methyl-2-sulpho-1-propyl(meth)acrylate, 2-methyl-1-sulpho-2-propyl(meth)acrylate, 3-bromo-2-sulpho-1-propylacrylate, 3-bromo-1-sulpho-2-propylacrylate, 3-chloro-2-sulpho-1-propylacrylate, 3-chloro-1-sulpho-2-propylacrylate, 1-bromo-3-sulpho-2-butylacrylate, 1-bromo-2-sulpho-3-butylacrylate, 1-chloro-3-sulpho-2-butylacrylate, 1-chloro-2-sulpho-3-butylacrylate, 3-bromo-2-sulpho-1-butylacrylate, 3-bromo-1-sulpho-2-butylacrylate, 3-chloro-2-sulpho-1-butylacrylate, 3-chloro-1-sulpho-2-butylacrylate, 1-chloro-2-methyl-3-sulpho-2-propylacrylate, 1-chloro-2-methyl-2-sulpho-3-propylacrylate, 1-chloro-2(chloromethyl)-3-sulpho-2-propylacrylate, 1-chloro-2-(chloromethyl)-2-sulpho-3-propylacrylate, 3-methoxy-2-sulpho-1-propylacrylate, 3-methoxy-1-sulpho-2-propylacrylate, 2-sulphocyclohexylacrylate, 2-phenyl-2-sulphoethylacrylate, 1-phenyl-2-sulphoethylacrylate, 3-sulpho-1-propylacrylate, 3-sulpho-1-butylacrylate, 4-sulpho-1-butylacrylate, sulphophenylacrylate, sulphophenylmethacrylate and 2-(sulphophenoxy)ethylacrylate. The preparation of such sulpho(C 1 -C 12 )alkyl(meth)acrylates is described in US-A-2,923,734. Suitable acrylamidoalkanesulphonic acids include, for instance, acrylamidopropanesulphonic acid, acrylamido-2-tetradecanesulphonic acid, acrylamido-2-dodecanesulphonic acid and acrylamido-2-decanesulphonic acid. The plastic dispersions may be aqueous or non-aqueous dispersions. Preference is given to the use of aqueous dispersions. The plastic dispersions can be obtained by any suitable means such as by generally known emulsion polymerizations. Dispersions based on sulphoalkylacrylates are described on, for instance, page 535 of 'Functional Monomers', (Volume 1, Ronald H. Yocum and Edwin B. Nyquist, 1973). The molecular weights of the dispersions can be analyzed by means of GPC, in which analysis the polymers are dissolved in tetrahydrofuran and filtered off over an 0.45 micrometre filter. Three linear columns are used with polystyrene as standard. The dispersions usually show a substantially gauss molecular weight distribution, the distribution being asymmetric with a range between 25,000 and 150.000 g/mole for the top of the greatest peak (calibrated with respect to narrow polystyrene standards). If the molecular weight is too high, the miscibility of the dispersion-coated pigment in plastics may be insufficient. In order to obtain the desired molecular weights, chain regulators such as, for instance, dodecyl mercaptan, carbon tetrachloride, n-butyl mercaptan and 2-mercaptoethanol may be necessary. The plastic dispersion can be mixed with a pigment paste in a ball mill or in a high-speed mixer. In such an aqueous paste the pigment is contained in a finely distributed state with the desired particle size which is preferably less han 5µm. The mixture consisting of dispersion and pigment paste can be dried by spray drying to form a pigment powder. The mixture consisting of dispersion and pigment paste can also be heated, causing coagulation. If necessary, the resulting product will be filtered, washed, dried and/or ground. In this manner the particle coated with a plastic dispersion can be obtained. The amount of pigment by weight (based upon the amount of dispersion by weight) may range within wide limits. Preferably the amount of pigment varies between 10 and 90% (wt) calculated based on the total weight of coated pigment by weight. If inorganic pigments are used, the amount is usually 50-75% (wt) pigment and 25-50% (wt) dispersion. If organic pigments are used, the amount is usually 25-35% (wt) pigment and 65-75% (wt) dispersion. If so desired, additives such as, for instance, metallic soaps, low molecular weight polymers, waxes and/or liquid esters of dicarboxylic acids may be used also in order to obtain virtually dust-free, easy-to-use and easy-to-meter products (masterbatches). Examples of suitable metallic soaps are magnesium, calcium and zinc stearate. Examples of suitable liquid esters of dicarboxylic acids are the esters of aromatic dicarboxylic acids such as dioctylphthalate. Other suitable additives are, for instance, stearylamide, ethylenedistearylamide, silica, hydrogenated castor oil and/or esters of pentaerythritol such as a monoester or tetraester of pentaerythritol, for instance an ester of a fatty acid with 12 to 18 carbon atoms. The above additives are described, for instance, in EP-A-290092 and EP-A-379751. The amount of coated pigment particles or colourant particles usually ranges between 0.1 and 20% (wt) calculated on the plastic. Suitable plastics include, for instance, polystyrene, ABS, PVC, polyesters, polyethyleneterephthalate, polyethylene, polypropylene and polycarbonate. The pigments and dispersions coated according to the invention can be used also in powder coatings, rubbers, insecticides, pharmaceutical products, paints, foodstuffs, printing inks, films laminates and the like. The pigment particles and colourant particles may be of an organic as well as an inorganic nature. The particle size is mostly between 0,01 µm and 100µm. Examples of suitable inorganic pigments include TiO 2 , ZnO, Sb 2 O 3 , ZrO, BaSO 4 /ZnS, TiO 2 /CaSO 4 , TiO 2 /BaSO 4 , Pb 3 O 4 , CdS(Se), Sb 2 S 3 , HgS, PbCrO 4 , Pb(OH) 2 , BaCrO 4 , SrCrO 4 , PbCrO 4 , PbO, Cr 2 O 3 , Ca 3 (PO 4 ) 2 , Fe 4 ((Fe(CN) 6 ) 3 , CaO.CuO.4 SiO 2 , CuO.Al 2 O 3 , 'metallic' pigment and carbon black. Suitable organic pigments include, for instance, azo compounds and ultramarine blue. Suitable pigments and colourants are described, for instance, in EP-A-104498. The invention is elucidated by means of the following non-restrictive examples. Example I Preparation of a plastic dispersion A flask (of 2 litres) provided with a cooler, thermocouple and stirrer was filled with 62 parts by weight demineralized water and 0.04 parts by weight sodiumdodecylbenzenesulphonate. This mixture was brought to 80°C. Subsequently were added 0.35 part by weight ammoniumpersulphate as initiator and a pre-emulsion consisting of 99 parts by weight styrene, 0.15 parts by weight dodecyl mercaptan, 3.5 parts by weight sodiumdodecylbenzenesulphonate, 1 part by weight 3-sulphopropylmethacrylate (K salt) and 30 parts by weight demineralized water in a period of three hours. After this addition in the 15 minutes the temperature was raised to 85°C. During a period of one hour a solution of 0.15 gramme ammonium persulphate in 3.1 grammes demineralized water was added. After 2 hours at 85°C the flask was cooled, filtered and drained. Example II The process according to Example I was repeated, with 20 parts by weight methylmethacrylate and 79 parts by weight styrene (instead of 99 parts by weight styrene) being incorporated. Example III The process according to Example I was repeated, with 20 parts by weight butylacrylate and 79 parts by weight styrene (instead of 99 parts by weight styrene) being incorporated. Comparative Experiment A The process according to Example I was repeated, with 2 parts by weight acrylic acid and 97 parts by weight styrene (instead of 99 parts by weight styrene) being incorporated. Comparative Experiment B The process according to Example I was repeated, with 3 parts by weight methacrylic acid and 96 parts by weight (instead of 99 parts by weight styrene) being incorporated. Dispersion according to I II III A B parts by weight demineralized water 62 62 62 62 62 sodiumdodecylbenzenesulphonate 0.04 0.04 0.04 0.04 0.04 styrene 99 79 79 97 96 methylmethacrylate 20 butylacrylate 20 acrylic acid 2 methacrylic acid 3 dodecyl mercaptan 0.15 0.15 0.15 0.15 0.15 sodiumdodecylbenzenesulphonate 3.5 3.5 3.5 3.5 3.5 3-sulphopropylmethacrylate (K salt) 1 1 1 1 1 demineralized water 30 30 30 30 30 Example IV Preparation of a pigment paste 3.85 parts by weight propylene glycol, 1.40 parts by weight water, 0.85 part by weight dispersant (Orotan 731 SD, 25% wt solution, Rohm and Haas), 0.10 part by weight dispersant (Surfynol 104E, Air Products), 0.10 part by weight antifoamer (Agitan 703, Munzing Chemie) and 19.70 parts by weight titanium dioxide (Kronos 2190, Kronos Titan) were mixed and, using a ball mill or pearl mill, ground to a Hegman fineness lower than 5. Example V Preparation of a pigment paste 125 parts by weight water, 20 parts by weight ethylene glycol, 45 parts by weight dispersant (SER AD FA 620, Servo) and 235 parts by weight pigment (Helio Blue 6900) were brought to a particle size of less than 5 µm by means of a ball mill. To the above mixture were subsequently added 200 parts by weight styreneacrylate dispersion (50% wt water), 5 parts by weight calciumstearate dispersion (50% wt water) and 25 parts by weight 2% hydroxyethyl cellulose solution, and the mixture was well stirred. This pigment paste was subjected to spray drying and contained 65% Helio Blue (dry on dry). Example VI 50 parts by weight of 50% aqueous solutions of the plastic dispersions according to Examples I-III and Comparative Experiments A-B were mixed in a high-speed mixer with 83 parts by weight pigment paste according to Example IV. The result was that TiO 2 was coated with the dispersion. Example VII 10 parts by weight of the TiO 2 coated according to Example VI were mixed in an extruder with 20 parts by weight polycarbonate. A visual analysis revealed that TiO 2 coated with dispersions according to any one of Examples I-III showed a good homogeneous distribution of pigment in the polycarbonate. On the other hand, the experiments based on TiO 2 coated with dispersions according to any one of Comparative Experiment A-B resulted in many agglomerates. Example VIII 50 parts by weight of 50% aqueous solutions of plastic dispersions according to Examples I-III and Comparative Experiments A-B were mixed in a high-speed mixer with 106 parts by weight of this pigment paste according to Example V, 1.25 parts by weight calcium stearate 50% and 6.25 parts by weight 2% hydroxyethyl cellulose solution. The result was that the pigment was coated with the dispersions. Subsequently, this mixture was dried by spray drying to form a dust-free powder. Example IX 10 parts by weight of the pigment coated according to Example VIII were mixed in an extruder at 150°C with 200 parts by weight polystyrene. A visual determination revealed that 'helio blue' coated with dispersions according to any one of Examples I-III showed a good homogeneous distribution in the polystyrene. On the other hand, the experiments with 'helio blue' coated with dispersions according to any one of Comparative Experiments A-B resulted in many agglomerates.

Claims: Use of a plastic dispersion as coating for inorganic and organic particles, such as pigment particles and colourant particles, characterized in that the plastic dispersion is a dispersion of a polymer based on a. 50-99% (wt) vinyl monomer, b. 0-50% (wt) (C 1 -C 12 ) alkyl(meth)acrylate, (C 1 -C 12 ) alkylitaconate, (C 1 -C 12 ) dialkylfumarate and/or (C 1 -C 12 ) dialkylmaleate, c. 0.1-5% (wt) monomer containing sulphonic acid groups, or a corresponding salt of it, and d. 0-0.3% (wt) organic unsaturated mono and/or dicarboxylic acid. Use according to claim 1, characterized in that the plastic dispersion Is a dispersion of a polymer based on a. 50-99% (wt) vinylaromatic monomer, b. 0-50% (wt) (C 1 -C 12 ) alkyl(meth)acrylate, c. 0.1-5% (wt) sulpho (C 1 -C 12 ) alkyl(meth)acrylate, or a corresponding salt of it, and d. 0-0.3% (wt) unsaturated mono- and/or dicarboxylic acid. Use according to any one of claims 1-2, characterized in that the % (wt) of organic unsaturated mono- and/or dicarboxylic acid is substantially 0% (wt). Use according to any one of claims 1-3, characterized in that the vinyl monomer is styrene. Use according to any one of claims 1-4, characterized in that the (C 1 -C 12 ) alkyl(meth)acrylate is methyl (meth)acrylate. Use according to any one of claims 1-5, characterized in that the monomer containing sulphonic acid groups is sulphopropyl(meth)acrylate and/or sulphoethyl(meth)acrylate.

Inventors: PONS DICK ADRIAAN, VAN DEN BERG MONIQUE, PONS, DICK ADRIAAN, VAN DEN BERG, MONIQUE
Applicants: DSM NV, DSM N.V.
Application year: 1991
Main classification: C09C3
IPC codes: C09B67, C09C3, C09C1