HU202890B - Process for producing cured polyester resin with improved elasticity - Google Patents

Abstract

Improved polyester resins are prepd. from aliphatic unsubstd. mono:carboxylic-acid anhydrides and satd. di:carboxylic-acids and/or anhydrides of 1:3-1:4 relative molar ratios and of 4C min. individual or mixed linear di:alcohol-ethers, as glycols, ion a glycol to acid, acid and anhydride or to mixed anhydride molar proportion of 1.1:1-1.2:1 range.

Description

FIELD OF THE INVENTION The present invention relates to an improved resilient cured unsaturated polyester resin which can be used alone or mixed with brittle polyester resins.

Unsaturated polyester resins in styrene, composed of maleic anhydride, phthalic anhydride (or other aromatic dicarboxylic acids) and glycols, are inelastic due to the high degree of crosslinking. Soft or flexible resins can be prepared by removing the double bonds of the monomer-free polyester molecular chain by condensation of the longer aliphatic carboxylic acids, i.e., diluting the double bonds. However, impact resistance and elongation at break do not increase as desired. The modifying aliphatic dicarboxylic acids used are primarily adipic acid and sebacic acid, however, which have the problem of altering the porosity conditions, i.e. reducing the solubility in styrene.

The preparation of such polyester resins is disclosed in German Patent No. 923,392 and U.S. Patent 2,423,093.

It is apparent from German Patent Application No. 850,610 that the incorporation of longer-chain saturated glycols into the macromolecule also has an elasticity enhancing effect. With the use of 1,4-butylene glycol, the tensile ratio of the system changes favorably.

However, in this case, problems arise in the esterification reaction during the preparation of the resin because the 1,4-glycols are prone to furan ring formation and thus do not fully participate in the polycondensation process, losing their glycol nature.

German Patent No. 815,542 discloses the partial or total substitution of bivalent alcohols with polyamines to provide highly elastic extensible polyester resins which, in practice, are unacceptable due to their extremely poor solubility in styrene and high commodities.

The possibility of replacing styrene with other monomers capable of copolymerization, in whole or in part, to reduce the brittleness, was sought. By using acrylonitrile instead of styrene, e.g. good results are obtained for reducing brittleness, but in this case the course of copolymerization is not sufficiently reproducible. It also has the disadvantage that acrylonitrile also tends to homopolymerize in the presence of maleate unsaturation, which often results in turbidity and inhomogeneity in the cured product. (Unsoturated Polyesters, Els. Púid. Comp. NY 1964.)

As a consequence, the use of acrylonitrile in the field of polyesters has probably been discouraged and is rarely discussed in the patent literature.

Attempts have been made to produce an unsaturated polyester resin with improved elasticity.

It has been found that when the resin is prepared from a linear dialkyl ether (glycol) having at least four carbon atoms and a mixture thereof and an aromatic saturated dicarboxylic acid, preferably phthalic acid and / or isophthalic acid and an aliphatic unsaturated carboxylic anhydride such as maleic anhydride a molar ratio of 1.1: 1.0 to 1.2: 1.0 and a molar ratio of unsaturated aliphatic acid anhydride-saturated aromatic dicarboxylic acid to anhydride of 1: 3 to 1: 4 to obtain a more flexible end product.

It has been found that if this ratio is kept below that given above, the elastic property (tensile elongation) of the cured polyester resin is much lower than that of the polyester resin of the present invention, while the resin has a relatively high tensile strength. By setting this ratio higher than that of the present invention, the resin may be further elasticized, but its hardness and tensile strength will be degraded to such an extent that the resin cannot be used in practice.

Thus, it has been found that, when a preferred molar ratio of unsaturated acid to saturated acid is observed, the resin has a dramatic increase in elasticity and tensile strength and hardness! values are also at an appropriate level for usability.

However, in our experiments, it has been found that the use of lower glycols or a mixture containing such glycols as starting materials instead of glycols having at least four carbon atoms also significantly reduces the elongation at break of the cured polyester resin.

When isophthalic acid is used in the reaction mixture, the polyester resin is polycondensed in two steps.

In the first step, diester formation of the high melting point isophthalic acid and glycol is carried out by reacting at a temperature of up to 20 ° C, then in the second step, maleic anhydride is added and the polyester resin is prepared at a temperature of up to 190 ° C.

If the starting mixture does not contain isophthalic acid, one-step condensation is carried out at 50-190 ° C since all reactants at this temperature form a homogeneous mixture, i.e. they can be melted.

The product of the present invention is used for the production of moldings, in particular printing molds.

The present invention relates to the preparation of a cured unsaturated polyester resin from an aliphatic unsaturated monocarboxylic anhydride and an aromatic saturated dicarboxylic acid and / or anhydride and glycol by one or two step condensation followed by dissolving the resin in a 30 to 40 weight percent monomer solution. wherein the glycol is a linear dialkyl ester having at least four carbon atoms or a mixture thereof and has a molar ratio of the acid to the acid anhydride or acid anhydride of from 1.1: 1 to 1.2: 1.

HU 202890 Β

The resilient polyester resin of the present invention is cross-linked with 30 to 40% by weight of styrene, based on the weight of the resin solution, in the presence of a known peroxide catalyst and accelerator, preferably cobalt naphthenate.

The resin, alone or mixed with brittle polyester resin, can be used for printing purposes such as printing plates, cracking larger molds or forming a polymer concrete substrate.

The following examples illustrate the process of the invention.

Example 1

In a four-neck resin boiler equipped with a stirrer, thermometer, gas inlet and column with a Rashig ring, 5.25 moles of diethylene glycol are weighed and the heater is switched on simultaneously with the start of the stirrer. When the internal temperature reaches 60-70 ° C, 4.0 moles of isophytic acid are gradually added with constant stirring.

The temperature is raised gradually. At 100 'C, N2 gas is continuously introduced into the reaction space. The condensation reaction starts at about 160 ° C and the water vapor released is continuously removed from the system. After the condensation has slowed down, the temperature of the reaction mixture is gradually raised further so that the maximum temperature does not exceed 200 ° C. The condensation was continued until an acid number of 15-20 was reached. This is the first stage of condensation, which takes 13 hours. The system is then cooled to 150 ° C and 1.0 molar of maleic anhydride is added to the vessel and 0.015% by weight of hydroquinone is added as a heat stabilizer. Continue the reaction with gradual heating until an acid number of 30 is reached. In this second stage of the reaction, the temperature of the system must not exceed 190 ° C.

The second stage of condensation takes 11 hours. The finished polyester condensate (I) is then cooled to 150 ° C and dissolved in styrene monomer (Π) with constant stirring. The weight ratio of I and II is 70:30.

Example 2

The following reactants were weighed into the apparatus of Example 1

1,2-propylene glycol 1.1 mol triethylene glycol 3.3 mol phthalic anhydride 3.0 mol maleic anhydride 1.0 mol

In this case, the resin is cooked in a so-called "one-step" reaction, i.e. all the feedstock is added to the reactor at the beginning of the process.

The condensation is carried out at 170 'C until the acid number is 18. The total resin cooking time is 26 hours.

Example 3

Example 1 is repeated, but using a mixture of 3.0 moles of isophthalic acid and 1.0 mole of phthalic acid instead of 4.0 moles of isophthalic acid.

Example 4 (Comparative)

The resin solution was prepared as in Example 1, but the molar ratio of maleic anhydride to isophthalic acid was changed.

The monomer content, acid number and iodine number of the liquid resin solution are determined according to MSZ 10097-82.

The tensile elongation and tensile strength of the cured resin are measured according to MSZ KGST 1199-78 and hardness according to "Barcol".

The composition of the resin solutions and the test results are as follows:

Mole ratio of raw materials 4/1 4/2 4/3 4/4 4/5 isophthalic 1.0 2.0 3.0 4.0 5.0 phthalic Anhydride - - - - - maleic anhydride 1.0 1.0 1.0 1.0 1.0 diethylene 2.2 3.3 4.4 5.5 6.6 Liquid resin solution styrene, crowd% 35 35 35 35 35 Acid number, mg / KOH / g 12.6 15.8 12.4 16.0 13.6 Viscosity, mPa.s At 25 'C 1210 1100 870 690 550 Hardened resin Hardness, Barcol 42 39 36 35 12 Breaking sil. N / mm2 63.9 60.4 49.0 43.0 8.1. Elongation at break,% 3.5 6.0 75.0 78.0 110.0

- 4/3 and 4/4 are resin solutions according to the invention. The results show that this composition has a dramatic increase in elongation at break, while also having a good tensile strength value.

Example 5 (comparative)

Example 2 is a one-step resin cooking. The composition of the resin solutions and their test results are given in the table. Assays were performed as described in Example 4.

Mole ratio of raw materials: 5/1 5/2 5/3 5/4 isophthalic - - phthalic Anhydride 1.0 2.0 3.0 4.0 maleic anhydride 1.0 1.0 1.0 1.0 diethylene 2.2 3.3 4.4 5.5 Liquid resin solution Styrene. t% 35 35 35 35 Acid number mgKOH / g 22.1 23.8 22.9 21.9 Visc. mPa.s, at 25 'C 998 845 785 710 Hardened Resin Hardness, Barcol 41 40 26 16 Tensile Elm. N / mm 45.5 36.5 30 28 % Elongation at break 2.0 8.6 65.0 69.0

HU 202890 Β

Examples 5/3 and 5/4 according to the invention result in a product having outstanding tensile elongation and at the same time adequate tensile strength.

6 * (comparative) example

Resin solutions of the composition of Example 1 were prepared by addition of propylene glycol in addition to diethylene glycol. The resin cooking is

Example 1.

The quality of glycol in the resin solutions and the value of the elongation at break of the cured resin are as follows:

diethylene glycol % propylene glycol % elongation at break% 100 0 75 (Example # 1) 80 20 26 60 40 6 40 60 3 20 80 2 0 100 2

The test results show that the use of a mixture containing less than or equal to four carbon atoms in glycol reduces the elongation at break.

Claims (1)

Patent Claim Point Process for the preparation of cured saturated polyester resin with improved elasticity from aliphatic unsaturated monocarboxylic anhydride such as maleic anhydride and / or anhydrides thereof, preferably from phthalic acid and / or isophthalic acid and / or its anhydride linear carbon ethers of four carbon atoms are employed in a molar ratio of 1.1: 1 to 1.2: 1 relative to the acid (s) and / or acid anhydride (s) by one or two step condensation followed by 3040% by weight of the resin. dissolving, curing, in a monomer, preferably styrene, characterized in that the starting molar ratio of maleic anhydride to saturated aromatic dicarboxylic acid (s) and / or acid anhydride (s) is between 1: 3 and 1: 4.