JPH062873B2 - Low shrinkage agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a shrinkage reducing agent used for unsaturated polyester resins.

(Prior Art) An unsaturated polyester resin composition has a high dimensional shrinkage rate (for example, 10%) upon curing, and therefore, a molded product obtained from the resin by mold molding, injection molding, etc., may have distortion, cracks, sink marks, etc. However, there are drawbacks such as the occurrence of defects, lack of smoothness on the surface of the molded product, and embossing of the reinforcing fibers used for molding. In order to eliminate these drawbacks, various studies have been conducted in recent years. For example, as in the invention disclosed in Japanese Patent Application Laid-Open No. 48-34289, unsaturated polyester resins have anti-shrinkage properties such as polystyrene and polymethylmethacrylate. By mixing and curing a thermoplastic polymer, it is possible to produce moldings with substantially no cure shrinkage, and the abovementioned drawbacks are considerably improved.

(Problems to be Solved by the Invention) However, ordinary polystyrene, polymethylmethacrylate, and other anti-shrinkage thermoplastic polymers have low dispersion stability in unsaturated polyester resin compositions, and the mixture is kept for a while (1- When left standing for 5 hours, the polymer has a drawback that it floats on the upper part of the composition, and it has a drawback that it is poorly compatible with fillers and other inorganic fillers and has poor dispersibility.

As a solution of these drawbacks, a shrinkage reducing agent composed of a lactone polymer having various end groups has been proposed, and as one of them, for example, a reaction product of phthalic anhydride and a lactone polymer has been proposed. There is. This has a carboxyl group at both ends, but when it is used as a low-shrinking agent, it has the drawback of poor solubility in the styrene monomer used at the same time. The reaction during synthesis does not proceed further than that. Therefore, a lactone polymer obtained by ring-opening polymerization using a compound having at least one hydroxyl group and at least one carboxyl group as an initiator, and having a low lactone polymer having at least one carboxyl group and at least one hydroxyl group as terminal groups Japanese Patent Application No. 59-59 has excellent solubility in styrene without impairing shrinkage.
It is disclosed in 103206. However, a polymer having carboxyl groups at both ends obtained by transesterification of a polyester having a carboxyl group at the end and a lactone is more excellent in low shrinkage than a lactone polymer having at least one carboxyl group and at least one hydroxyl group. It has been found that the compound has the properties and solubility in styrene, and the present inventors disclosed it in Japanese Patent Application No. 59-174179.

Further progressing this research revealed that when a polymer obtained by reacting a polyester having a carboxyl group at the end with an alcohol or lactone having a valence of 3 or more was used as a shrinkage-reducing agent, an unsaturated polyester having excellent surface smoothness properties was obtained. The inventors have found that a resin can be obtained and have reached the present invention.

(Structure of the Invention) That is, the present invention is "synthesized from a polyester resin having a terminal carboxyl group synthesized from a polyhydric alcohol, a polybasic acid or an acid anhydride thereof, a lactone and a polyhydric alcohol having a valence of 3 or more. It is a low-contraction agent for unsaturated polyesters characterized by comprising a lactone polymer.

The lactones used in the present invention have 4 or more, preferably 6 or more carbon atoms in the ring. A preferred lactone is a 5-membered to 8-membered lactone, and examples thereof include ε-caprolactone, γ-halerolactone, β-butyrolactone and the like. The polyhydric alcohol used in the present invention includes dihydric, trihydric, and tetrahydric or higher alcohols, such as ethylene glycol, propylene glycol, 1,3-butylene glycol, 2-methylpropanediol, 1,4. -Butylene glycol, neopentyl glycol, 1,6-hexanediol, 1,2-
Dodecanediol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, ditaerythritol, hydroxypivalic acid neopentyl glycol ester, 1,4-cyclohexanedimethanol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, And its water additive 4-hydroxyhydroquinone etc. can be used. Alternatively, these can be used in combination. The polybasic acid or its anhydride, which is the second component of the polyester resin having a terminal carboxyl group used in the present invention, includes:
Maleic acid, succinic acid, fumaric acid, adipic acid, sebacic acid, azelaic acid, dodecane diacid, phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid , Trimellitic acid or their anhydrides can be used. Alternatively, these may be used in combination.

In the present invention, lactones are added to the lactone polymer in an amount of 30 to 95
It is necessary to make it contain by weight%.

If the lactone content is less than 30% by weight, the water resistance and low-temperature characteristics of the resin produced will deteriorate. On the other hand, if the amount is more than 95% by weight, the compatibility of the lactone with the solvent is deteriorated or the melting point of the lactone polymer is increased due to the crystallinity of the lactone, which is not preferable.

Now, a method for synthesizing the lactone polymer of the present invention will be described. First, the polyhydric alcohol, the polybasic acid and the reactor are charged. At this time, when the number of moles of polyhydric alcohol is n, the number of moles of polybasic acid is added in a ratio of n + 1. The reaction temperature is 100
React at ℃ ~ 230 ℃.

When a predetermined amount of water is dehydrated, a polyester having a terminal carboxyl group is obtained.

This reaction proceeds even without a catalyst, but a catalyst usually used for an esterification reaction may be used. Examples thereof include titanium compounds such as sulfuric acid, paratoluene sulfonic acid, and tetrabutyl titanate. The molecular weight of the terminal carboxyl group polyester thus obtained is 300 to 20,
It is 000, preferably 1,000 to 7,000. Also, the molecular weight distribution M
Those having W / MN = 2 to 15 are particularly effective as a shrinkage reducing agent.

The lactone is then added to the resin in an amount of 30 to 95% by weight, preferably
A lactone catalyst and a polyhydric alcohol having a valence of 3 or more are added to the polyester resin so that the content of the polyester resin is 60 to 90% by weight, and the polyester resin is reacted. The reaction temperature is 130 ° C to 240 ° C, preferably 160 ° C to 230 ° C.
℃. Also, passing an inert gas such as nitrogen gas during the reaction gives good results on the hue of the resin and the like.

Examples of the catalyst used in this reaction include titanium compounds such as tetrabutyl titanate and tetrapropyl titanate, dibutyltin laurate, tin octylate, dibutyltin oxide, stannous chloride, stannous bromide, stannous iodide, etc. It is preferable to use -50 ppm, preferably 0.1-10 ppm. Further, among these catalysts, particularly titanium compounds show sufficient catalytic activity for transesterification reaction.

Examples of the trihydric or higher polyhydric alcohol used in the present invention include pentaerythritol, dipentaerythritol, diglycerin, polyglycerin, poval, celluloses and sugars.

This polyhydric alcohol having 3 or more valences may be used alone or in combination of two or more. Since these polyhydric alcohols play a role as a polymerization initiator for lactones, the addition amount thereof is preferably the minimum amount necessary for initiating the polymerization of lactones.

If the amount of the polyhydric alcohol having a valence of 3 or more is large, the hydroxyl value and the acid value of the product increase, which is not preferable.

Therefore, the added amount is preferably in the range of 0.1% to 8%.

As a method for synthesizing the shrinking agent for unsaturated polyester of the present invention, a polyester resin having a terminal carboxyl group synthesized from a polyhydric alcohol, a polybasic acid or an acid anhydride thereof, and a high-strength compound previously synthesized. A method of carrying out a transesterification reaction with a polylactone having a degree of polymerization may be used. Polyester polyols with carboxyl groups at both ends, lactones, a catalyst and a polyhydric alcohol with a valence of 3 or more are reacted at a reaction temperature of 160 ° C to 230 ° C. You can Then, a transesterification reaction occurs between the ester chain of the polyester resin having carboxyl groups at both ends and the lactone chain to obtain a polybasic acid / polyhydric alcohol / lactone random copolymerized polyester.

In order to synthesize a lactone-modified polyester polyol having a low melting point and good compatibility with a solvent, it is necessary to sufficiently cause a transesterification reaction to form a random copolymer as described above.

The molecular weight of the lactone polymer thus prepared is usually 50.
It is about 0 to 100,000. The molecular weight can be adjusted by determining the molecular weight of the polyester having carboxyl groups at both ends and the molar ratio of the polymerization initiator and the lactone.

(Effects of the Invention) The shrinkage-reducing agent of the present invention can be extremely advantageously used for unsaturated polyester resins.

Next, the present invention will be described with reference to examples, but the present invention is not limited thereto.

In the examples, all parts are parts by weight.

Synthesis Example 1 1095 parts of adipic acid were added to a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a condenser with a dehydration tube.
6-hexanediol 767 parts, tetrabutyl titanate
Dehydration was started at 140 ° C under a nitrogen atmosphere, the temperature was raised to 220 ° C as the dehydration progressed, and the reaction was continued until the dehydration amount reached 234 parts.
A polyester having an Hmg / g of 70.2 and an average molecular weight (converted to polystyrene) of MN = 2480 was obtained.

Separately, in a similar device, polyester 300 obtained by the above reaction
Part, ε-caprolactone 1677 part, pentaerythritol
23 parts, tetrabutyl titanate 0.02 parts were charged, 210 ℃
When reacted for 10 hours, the acid value (KOHmg / g) was 10.
3, a lactone polymer having a hydroxyl value (KOHmg / g) of 18.6 and an average molecular weight (in terms of polystyrene) of MN = 5760 was obtained.

Synthesis Example 2 1392 parts of adipic acid, 954 parts of diethylene glycol, 0.002 parts of tetrabutyl titanate were placed in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a condenser with a dehydration tube.
Part is charged, dehydration starts at 140 ℃ under nitrogen atmosphere,
As the dehydration progresses, the temperature rises to 220 ° C and the dehydration amount becomes 3
When the reaction was continued until reaching 28 parts, the acid value (KOHmg /
g) 23.8, average molecular weight (polystyrene equivalent) MN = 6900
Of polyester was obtained.

Separately, in a similar device, polyester 825 obtained by the above reaction
Parts, ε-caprolactone 4573 parts, pentaerythritol, 102 parts, tetrabutyl titanate 0.02 parts, and 2
After reacting at 10 ℃ for 10 hours, the acid value (KOHmg /
g), a hydroxyl value (KOH mg / g), and an average molecular weight (in terms of polystyrene) MN = 6240 were obtained.

Example 1 Unsaturated polyester resin obtained from maleic anhydride and isophthalic acid and 1,2-propylene glycol 15
Parts, 25 parts of styrene, 10 parts of the resin obtained in Synthesis Example-1, 1 part of t-butylperbenzoate, 1 part of MgO, 200 parts of calcium carbonate, and 4 parts of zinc stearate, and mixed and further sheet-molded from the paste. A sheet material containing 100 parts of glass fiber having a fiber length of 1 cm was manufactured in a compound machine. After aging this for 1 day at 40, 150 ℃ 1
When press molding was performed for 3 minutes at a pressure of 00 kg / cm 3, a smooth plate having a uniform surface was obtained.

The linear shrinkage rate was 0.11% (expansion), which was a very good result.

Example 2 Unsaturated polyester resin 30 similar to that used in Example 1
Parts, styrene 50 parts, resin 20 parts obtained in Synthesis Example-2, t
-Butyl perbenzoate 1 part, calcium carbonate 180
Parts, 1 part of MgO, 3 parts of zinc stearate are mixed and stirred,
The paste-like material kneaded into a glass fiber mat is made into glass fiber.
It was coated so that it would be 100 parts, pressed by a roll to impregnate the glass fiber, and allowed to stand at 40 ° C for 1 day to obtain a sheet molding compound. When this was press-molded at 140 ° C. and 100 kg / cm ³ for 4 minutes, a plate having a smooth surface and no warpage was obtained. The linear shrinkage was 0.132% (expansion).

Claims (1)

[Claims] 1. A polyester resin having a terminal carboxyl group synthesized from a polyhydric alcohol, a polybasic acid or an acid anhydride thereof, and a lactone polymer synthesized from a lactone and a trihydric or higher polyhydric alcohol. A low-contracting agent for unsaturated polyesters characterized by: