FI82257C - FLUORIDFOERENINGAR INNEHAOLLANDE TI02-PIGMENT. - Google Patents

Description

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The invention relates to a pigment consisting of alumina-coated rutile TiO2 particles, wherein the pigment is associated with 0.05-5% by weight of TiO2.

Na7Ce6F31 10 K7Ce6F31

Li7Ce6F31 or (NH4) 7Ce6F31.

The invention also relates to a paper laminate and a coating composition containing this pigment.

Paper laminates are products widely used in the construction industry for the manufacture of table tops and the like. Laminates generally consist of pa-20 base impregnated with TiO 2 pigment and embedded in a polymer matrix. Such laminates have an unfortunate tendency to cause discoloration when exposed to ultraviolet light, and this reduces their value because in many cases they are exposed to such radiation. The pigment of the present invention is highly resistant to such opaque discoloration when exposed to ultraviolet light, and when used in the manufacture of paper laminate, it provides a product with significantly better lightfastness than a product made using a conventional TiO 2 pigment.

The pigment according to the invention consists of rutile-TiO2 particles which are conventionally coated with alumina. The coating is usually 1 to 8%, preferably 3 to 5% by weight of the pigment. Associated with the moieties are 2,825,257 of the above-mentioned trifluoride compound in a concentration of 0.05 to 5% by weight of TiO 2, preferably 0.2 to 0.6%. The phrase "associated with the moieties" means that some of the fluoride compounds are adsorbed on the surfaces of the 5 TiO 2 moieties and that some are within the coatings themselves.

The concentration of fluoride compounds in the pigment can be determined as follows: (a) Slurry 200 g of the pigment to be analyzed in 10 ml of deionized distilled water twice.

b) Adjust the pH of the slurry to 10.0 with 50% aqueous sodium hydroxide solution.

c) The slurry is stirred for 24 hours in a sealed container.

D) The slurry is filtered and the filtrate is analyzed by ion chromatography to determine the amount present as a percentage of the weight of the pigment.

Of the fluoride compounds (NH4) 7Ce6F31, is preferred.

The TiO 2 used to prepare the pigment of the invention may be of the ordinary rutile species prepared by either the chloride or sulfate method.

The pigment according to the invention can be prepared by first preparing an aqueous slurry containing 200 to 400 g of TiO2 per liter. This slurry is heated to between 45 and 70 ° C and maintained there for the remainder of the manufacturing process. The fluoride compound is then formed in situ in the slurry. This is done according to the illustrative equation as follows 31NaF + 6Ce (SO4) 2 - * Na7Ce6F31 + 12Na2SO4 30

Typical cerium salts that can be used include ammonium cerinitrate, cerinitrate and cerisulfate. Cerium sulfate is preferred.

The amounts of suitable cerium salt and fluoride required to achieve the desired concentration of fluoride compound

II

3,825,257 sex in pigment is added to the slurry in proportions corresponding to the stoichiometric amounts of the equation.

The alumina is then doped on the TiO2 particles by adding enough sodium aluminate to the slurry to give a concentration of 1-8% by weight of TiO2. Acid, usually sulfuric acid or hydrochloric acid, is added simultaneously to maintain the pH of the slurry between 6.5-9 during the precipitation step. After the addition of aluminate is complete, the curing is allowed to proceed in the slurry while stirring for 15-30 minutes.

The resulting pigment is then separated from the liquid by filtration or centrifugation, washed with water and then dried.

The pigments obtained according to the invention can be used for the production of paper laminates in any conventional manner, typically by mixing the pigment with the pulp and then making paper in the usual way, impregnating this paper with a resin, usually melamine-formaldehyde or urea-formaldehyde resin, and then curing the mixture. These methods are described in more detail in U.S. Patent 4,239,548.

Coating compositions can be prepared using the pigments of the invention in any conventional manner, by mixing the pigment with a film-forming component and a liquid carrier.

examples

In the following examples, all parts are based on weight 30.

Example 1 3000 parts of rutile-TiO2 were dispersed in 7500 parts of distilled water to give a slurry pH of 3.85. The slurry was then heated to 50 ° C and maintained at this temperature, followed by the addition of 30 parts of sodium fluoride with stirring. The pH of the slurry at this time was 9.1.

140 parts of a solution containing 85.5 parts of cerisulfate in 1000 parts of water were then added to the slurry within 5 minutes while stirring at 50 ° C. At this time, the pH of the slurry was 2.7.

343 parts of an aqueous solution of sodium aluminate (containing 350 parts equivalent of Al 2 O 3 per 1000 parts of water) were then added to the slurry over 30 minutes while stirring at 50 ° C. During this addition, the pH of the slurry was maintained at approximately 7.5 by the addition of concentrated sulfuric acid.

After the addition of sodium aluminate was complete, the slurry was stirred for 30 minutes at 50 ° C-15 ° C. The TiO 2 was then separated by filtration, washed with water, dried and micronized.

The resulting pigment had Na7Ce6F31 associated with it.

Example 2 3000 parts of rutile-TiO2 were dispersed in 7500 parts of distilled water to give a slurry pH of 3.8. The slurry was then heated to 50 ° C and maintained at this temperature, 175 parts of a solution containing 85.5 parts of cerisulfate in 1000 parts of water were added over 5 minutes. The pH of the slurry at this time was 1.65.

30 parts of ammonium bifluoride were then added to the slurry with stirring at 50 ° C. The slurry was then kept at 50 ° C with stirring for 10 minutes.

30,343 parts of an aqueous solution of sodium aluminate (containing 350 parts of the equivalent of Al 2 O 3 per 1000 parts of water) were then added to the slurry over 30 minutes while stirring at 50 ° C. During this addition, the pH of the slurry was maintained at approximately 7.5 by the addition of 35 concentrated sulfuric acid.

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After the addition of sodium aluminate was complete, the slurry was stirred for 30 minutes at 50 ° C. The TiO 2 was then separated by filtration, washed with water, dried and micronized.

The resulting pigment had (NH4) 7Ce6F31 associated with it.

Claims (5)

1. Pigment consisting of rutile T102 particles, characterized in that the particles are coated with alumina and the pigment contains associated 0.05 - 5% by weight of TiO2 Na7Ce6F31 K7Ce6F3i 10 Li7Ce6F31 or (NH4) 7Ce6F31. 2. A paper laminate containing paper and pigment consisting of rutile-TiO 2 particles in a hardened matrix, characterized in that the particles are coated with alumina and the pigment contains associated 0.05 to 5% by weight of TiO 2. 20 Na7Ce6F31 K7Ce6F3i Li7Ce6F31 or (NH4) 7Ce6F31. Coating composition containing pigment consisting of rutile-TiO 2 particles, layer-forming material and a liquid carrier, characterized in that the particles are coated with alumina and the pigment contains associated with 0.05 to 5% by weight of TiO 2. Na7Ce6F31 K7Ce6F3i 35 Li7Ce6F31 or (NH4) 7Ce6F31.