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Formaldehyde-reduced dispersion of microcapsules made from melamine-formaldehyde resin

A technology of melamine and formaldehyde resin, applied in the field of calcium salt

Active Publication Date: 2008-06-25
BASF AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the resulting dispersion has a low formaldehyde content, the stability of the microcapsules and the viscosity of the microcapsule dispersion are adversely affected by the addition of urea prior to curing

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] 400 g of a 5% strength fluoran reactive dye mixture in a 80:20 ratio mixture of diisopropylnaphthalene and linear alkanes (boiling point 220° C.)  I-2RN, 20 parts of Pergascript I-2GN, 8 parts of Pergascript I-G, 67 parts of Pegascript I-R, from CIBA) solution, 69 g of 70% strength methylated melamine-formaldehyde resin (the molar ratio of melamine: formaldehyde: methanol is 1: 3.9: 2.4) solution, 64g of 20% strength poly-2-acrylamido-2-methylpropanesulfonic acid / sodium salt solution (K value is 123, Brookfield viscosity is 770mPa.s), 350g of tap water and 15 g of 10% strength formic acid were sequentially introduced into a cylindrical 2L stirred vessel having a continuously adjustable disperser installed therein with a commercially available dispersing disc with a diameter of 50 mm, and by adjusting the stirring speed to Processing at a peripheral speed of about 20 m / s results in a capsule dispersion. The temperature was maintained at about 35°C.

[0051] After disp...

Embodiment 2

[0061] The procedure is as described in Example 1, but: After reaching a curing temperature of 80° C., the feed of a 67.2% strength aqueous slurry consisting of melamine / urea in the weight ratio 6.7:3.3 is started and metered in within 90 minutes A total of 37.5 g of slurry. During this time, the pH was kept constant at 4.4 with 25% strength formic acid (HCOOH). Then 5 g of a 50% strength calcium hydroxide slurry was added, followed by 24 g of a 25% strength sodium hydroxide solution. The dispersion has a pH of 11.0. Post curing was carried out at 80°C and pH 11.0 for 30 minutes. After this solidification period of a total of 120 minutes, the dispersion was cooled to room temperature. The measured pH was 11.2.

[0062] Analysis of the free formaldehyde content of the cold water extract gave a value of 20 ppm and of the dispersion gave a value of 0.01%.

Embodiment 3

[0064] The procedure was as described in Example 1, but the addition of 25% strong sodium hydroxide solution was reduced to 16 g. The dispersion has a pH of 10.6. Post curing was carried out at 80°C and pH 10.6 for 30 minutes. After this solidification period of a total of 120 minutes, the dispersion was cooled to room temperature. The measured pH was 9.7.

[0065] Analysis of the free formaldehyde content in the cold water extract gave a value of 40 ppm and in the dispersion gave a value of 0.02%.

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Abstract

The present invention relates to the use of calcium salts for reducing the formaldehyde emission of microcapsule dispersions based on melamine-formaldehyde resins. The invention also relates to a process for the preparation of a dispersion of microcapsules by condensation of partly methylated melamine-formaldehyde resin in water, in which the substantially water-insoluble material forming the capsule core is dispersed, in the presence of an anionic protective colloid, and to the dispersions of microcapsules which are obtained by this process and to the use thereof for the preparation of printing inks and paper coating materials.

Description

technical field [0001] The present invention relates to the use of calcium salts for reducing formaldehyde emissions from microcapsule dispersions based on melamine-formaldehyde resins. The present invention also relates to a process for the preparation of microcapsule dispersions by condensing partially methylated melamine-formaldehyde resins in water in the presence of an anionic protective colloid in which is dispersed a substantially water-insoluble material forming the capsule core , to a dispersion of microcapsules obtained by this process, and to the use of this dispersion for the preparation of printing inks and paper coating materials. Background technique [0002] Microdispersed particles, which may have a diameter of about 0.1-100 μm, have a wide range of applications in various fields. For example, they are used as solid balls in polishes and / or cleaners, as spacers in printing inks, as measuring volumes for medical observation under a microscope, etc. In addit...

Claims

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Application Information

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IPC IPC(8): C08K3/22C08J3/00C08L61/28B01J13/14C09D11/02D21H21/54
CPCC08K3/22C08K2003/2206C08L61/20
Inventor H·艾泽曼J·内尔沃R·比亚斯托驰G·弗兰克
Owner BASF AG