CS264919B1 - Process for preparing binders for physically drying paints - Google Patents

Abstract

The problem of preparing a binder for predominantly physically drying coatings is solved, enabling the preparation of varnishes and paints with an increased content of non-volatile components and at the same time very good resistance to weathering, reduced thermoplasticity and improved adhesion to a wide range of base materials. The method of preparing the binder consists in polycondensation of 1 mole of a dicarboxylic aromatic acid with 8 carbon atoms or its anhydride or dimethyl ester or its mixture with a dicarboxylic aliphatic acid with 6 to 10 carbon atoms with 1.02 to 1.2 moles of pentaerythritol and 0.1 to 1.0 moles of a monocarboxylic aliphatic acid with 6 to 20 carbon atoms and an average of no more than 1.5 double bonds in the chain or with the same amount of an aromatic acid with 7 to 11 carbon atoms, at 140 to 240 °C to form a polyester product with a softening point of at least 80 °C. The solution can be used in the production of paints.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for preparing a binder for physically drying coatings and to the problem of a binder which enables the preparation of paints and paints having an increased content of nonvolatile fractions and very good weather resistance, reduced thermoplasticity and improved adhesion to the substrate.

Methods are known for preparing binders for lacquers and other paints based on drying or semi-drying oils or fatty acids derived therefrom, aromatic dicarboxylic acids or their anhydrides and aliphatic polyols, in which the molar ratios of the individual components ensure a high proportion of reactive groups allowing their oxypolymeric drying at normal temperature. However, the disadvantages of these binders are their low drying rate and relatively easy radiation-oxidative degradation of the lacquer film due to residual reactive groups. Products in which the content of these groups is substantially reduced require, according to known methods of preparation, for their curing, a reaction with crosslinking additives, which takes place in one-component systems at a substantially elevated temperature. On the other hand, methods for preparing binders that dry at normal temperature by a physical mechanism are known, by polymerizing suitable monomers into polymer dispersions or by dissolving suitable polymers. A disadvantage of polymer dispersions is that they generally do not provide sufficiently glossy and hard lacquer films. Polymer solutions, on the other hand, do not allow non-volatile contents higher than 30% due to their high viscosity.

The essence of the binder preparation process which removes these drawbacks is that 1 mol of a dicarboxylic aromatic acid of 8 carbon atoms or its anhydride or dimethyl ester or a mixture thereof with a dicarboxylic aliphatic acid of 6 to 10 carbon atoms is heated with 1.02 to 1.2 moles of pentaerythritol and 0.1 to 1.0 moles of monocarboxylic aliphatic acid of 6 to 20 carbon atoms and an average of at most 1.5 double bonds in the chain or with the same amount of monocarboxylic aromatic acid of 7 to 11 carbon atoms, at 140 to 240 ° C until a polyester product with a softening point of at least 80 ° C is formed.

The binders prepared according to the invention are suitable for the preparation of lacquers and paints for a wide range of applications, from protective and decorative coatings of wood, through the treatment of building materials, protective and insulating surface treatment of metals to plastics. They are soluble in alcoholic solvents or in mixtures thereof with aromatic or aliphatic hydrocarbons. If necessary, they can be dissolved in pure alcohol to provide a relatively environmentally friendly paint.

Lacquers based on 50% solutions of these binders in a suitable solvent dry at normal temperature in a thickness of 50 µm on any substrate within two hours. After 3 days after application, they have a surface hardness equivalent to at least 30% of the glass hardness and an electrical strength of at least 100 kV / mm which will not drop by more than half after storage in water for 24 hours. When exposed to elevated temperatures of up to 200 ° C, their films do not show appreciable tackiness and also do not degrade significantly; in particular their mechanical resistance to direct bending is not lost even after 100 hours at 200 ° C.

A significant advantage of the binders of the present invention and their coating films is their adhesion to an unusually wide range of materials including such problematic substrates as polyethylene, polypropylene, PVC, chromium and aluminum. In addition, their increased resistance to weathering makes them suitable for surface protection of all kinds of building materials.

Example 1

80.70 g (0.3 mol) of soybean oil fatty acids, 140.23 g (1.03 mol) of pentaerythritol and 148.13 g (1.0 mol) of phthalic anhydride are heated together to 180 ° C and then stirred with stirring It shall be heated at a rate such that the temperature of the outgoing vapors does not exceed 120 ° C. After reaching 230 ° C, the temperature is maintained until the acid number of the product falls below 10 mg KOH / g. 345 g of a resin product having a softening point of 97 [deg.] C. according to the ring-ball method are obtained. Product obtained

CS 264 919 B1 is unrestrictedly soluble in butanol, in alcohol, as well as in 1: 1 mixtures thereof with xylene. A 50% solution of the product in butanol dries at a thickness of 30 µm for 2 hours to step 2 and after 3 days provides a film of 31% glass hardness according to the pendulum test. After 3 days, the film can withstand heating up to 200 ° C without becoming sticky and a load of 200 ° C for 100 hours without losing its ability to bend without mechanical failure. Its electrical strength is 151 kV / mm, after 24 h storage in water at 20 ° C 79 kV / mm.

Example 2

134.2 g (0.5 mol) of sunflower oil fatty acids, 145.7 g (1.07 mol) of pentaerythritol and 166.14 g (1.0 mol) of isophthalic acid are reacted as described in Example 1. 399 5 g of product having an acid number of 6.1 mg KOH / g and a softening point of 82 ° C. The product is freely soluble in 1: 1 butanol, alcohol and mixtures thereof with xylene. A 50% solution of the product in butanol dries at a thickness of 30 µm for 1.7 hours to stage 2 and after 3 days provides a film with a hardness equivalent to 33% of the glass hardness. The film can withstand temperatures of 200 ° C for 100 hours without losing mechanical bending resistance. Its electrical strength is 158 kV / mm, after 24 h in water 81 kV / mm.

Example 3

143.8 g (0.5 mol) of stearic acid, 140.23 g (1.03 mol) of pentaerythritol, 194.12 g (1.0 mol) of dimethyl terephthalate and 1.0 g of dibutyltin dilaurate are heated together with stirring The temperature is increased by 10 ° C for 30 min up to 240 ° C, at which level the mixture is maintained to an acid value of 4.0 mg KOH / g. 403.5 g of a resin product having a softening point of 81 [deg.] C. and a solubility similar to that of the previous cases are obtained. A 50% solution of the product in butanol dries at a thickness of 30, uin for 2.5 h to step 2 and after 3 days the film provides a hardness of 31.5% glass. The film can withstand temperatures of 200 ° C for 200 h without losing mechanical bending resistance. Its electrical strength is 156 kV / mm, after 24 h in water at 20 ° C it drops to 85 kV / mm.

Example 4

115.2 g (0.728 mol) of pelargonic acid, 29.23 g (0.20 mol) of adipic acid,

155.35 g (0.80 mol) of dimethyl terephthalate, 140.23 g (1.03 mol) of pentaerythritol and 1.0 g of dibutyltin dilaurate were reacted together as described in Example 3 until the acid number of the product was 6.0 mg KOH /G. 366 g of a resin product having a softening point of 91 [deg.] C. are obtained, the solubility of which is similar to that of the previous cases. A 50% solution of the product in butanol dries at a thickness of 30 µm for 2.2 h to step 2 at 20 ° C and after 3 days gives a 33.2% glass hardness. It can withstand a load of 200 ° C for 100 h without mechanical agitation and loss of resistance to direct bending after cooling to normal temperature.

Example 5

61.06 g (0.5 mol) of benzoic acid, 140.23 g (1.03 mol) of pentaerythritol and 194.19 g (1.0 mol) of dimethyl terephthalate are reacted together according to the procedure of Example 1 until the acid number of product 9 is reached. 0 mg KOH / g. 320 g of a product with a softening point of 125 DEG C. are obtained, the solubility of which is similar to the products of the previous cases. A 50% solution of the product in butanol dries at a thickness of 30 µm at 20 ° C for 1.3 h to a drying degree of 2 and after 3 days yields 39.8% glass hardness. It can withstand temperatures of 200 ° C for 200 hours without mechanical agitation and loss of mechanical resistance to direct bending.

Example 6

61.06 g (0.5 mol) of benzoic acid, 145.68 g (1.07 mol) of pentaerythritol and 148.13 g (1.0 mol) of phthalic anhydride were reacted together according to the procedure of Example 1 to reach the number

CS 264 919 B1 acidity of the product 8.0 mg KOH / g. 325 g of a product with a softening point of 111 DEG C. are obtained, the solubility of which is similar to the products of the previous cases. A 50% solution of the product in butanol dries at a thickness of 30 µm at 20 ° C for 1.5 hours to Stage 2 and after 3 days gives 39.6% glass hardness. Its heat resistance is similar to that of the product of Example 4.

Example 7

56.49 g (0.2 mol) of rapeseed oil fatty acids, 138.38 g (1.02 mol) of pentaerythritol and 148.13 g (1.0 mol) of phthalic anhydride were reacted together according to the procedure of Example 1 until the acid number was reached 9.0 mg KOH / g. 321.4 g of product are obtained having a softening point of 102 DEG C. and a solubility similar to that of the previous cases. A 50% solution of the product in butanol dries at 30 [mu] m at 20 [deg.] C. for 2 h to stage 2 and after 3 days yields 33.2% glass hardness.

Example

112.0 g (0.4 mol) of sunflower oil fatty acids, 144.32 g (1.06 mol) of pentaerythritol and 148.13 g (1.0 mol) of phthalic anhydride are reacted together according to the procedure of Example 1 to reach the acid number of product 8.0 mg KOH / g. 377 g of product having a softening point of 85 DEG C. and a solubility analogous to that of the previous cases are obtained. A 50% solution of the product in butanol dries at a thickness of 30 [mu] m at 20 [deg.] C. to stage 2 for 3.2 h and gives 31.2% of glass hardness after 3 days. Its heat resistance is similar to the previous product.

Claims (1)

SUBJECT OF THE INVENTION Process for preparing a binder for physically drying paints, characterized in that 1 mol of aromatic dicarboxylic acid of 8 carbon atoms or its anhydrides or dimethyl ester or a mixture thereof with an aliphatic dicarboxylic acid of 6 to 10 carbon atoms is heated with 1.02 to 1.10 mole of pentaerythritol and 0.1 to 1.0 mol of aliphatic monocarboxylic acid of 6 to 20 carbon atoms and an average of at most 1.5 double bonds in the chain or with the same amount of aromatic monocarboxylic acid of 7 to 11 carbon atoms, at 140 to 240 ° C until a polyester product having a softening point of at least 80 ° C is formed.