JPH078946B2 - Low shrinkage agent - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a shrinkage reducing agent 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, and, for example, as shown in the invention disclosed in JP-A-48-34289, unsaturated polyester resin has polystyrene,
By mixing and curing an anti-shrinkable thermoplastic polymer such as polymethylmethacrylate, it is possible to produce a molded article having substantially no cure shrinkage, and the above-mentioned drawbacks are considerably improved. Has become.

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

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 It has been disclosed in Japanese Patent Application No. 59-103206 that it has excellent dissolution properties in styrene without impairing the shrinkability.

However, this carboxyl group and hydroxyl group are both 1
A polymer having carboxyl groups at both ends obtained by transesterification of a polyester having a carboxyl group at the terminal and a lactone is more excellent in low shrinkage and solubility in styrene than a lactone polymer having at least one The inventors of the present invention disclosed in Japanese Patent Application No. 59-174179.

Further research has been promoted. When a polymer obtained by reacting a polyester having a carboxyl group at the terminal with an alcohol or lactone having a valence of 3 or more is used as a body shrinking agent, a cured resin having excellent surface smoothness properties can be obtained. The present inventors disclosed it in Japanese Patent Application No. 60-134788.

However, because it causes so-called scumming, which is a slight separation and floating on the surface of the molded product, when this research was pushed forward this time, the reaction between the polyester having a carboxyl group at the terminal and a trivalent or higher alcohol or lactone By using the polymer obtained by reacting an acid anhydride with the polymer obtained by as a shrinkage reducing agent, in addition to obtaining a cured resin having excellent surface smoothness characteristics, in an unsaturated polyester resin composition It was found that the nuclear polymer having particularly excellent dispersion stability does not float above the composition, and the present invention was completed.

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

The lactones used in the present invention have 4 or more, preferably 6 or more carbon atoms in the ring.

Preferred lactones are 4-membered to 8-membered lactones such as ε-caprolactone, γ-valerolactone and β-butyrolactone.

Further, the polyhydric alcohol used in the present invention includes dihydric and trihydric alcohols.
And alcohols having a valency of 4 or more, for example, 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, dipentaerythritol, hydroxypivalic acid neopentyl glycol ester, 1,4-
Cyclohexanedimethanol, an ethylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A, and a water additive 4-hydroxyhydroquinone thereof can be used, and these can also 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, It is possible to use phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, trimellitic acid or their anhydrides, or to use them in combination. it can.

Further, examples of the aliphatic polybasic acid anhydride to be reacted with the lactone polymer used in the present invention include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride and methylanhydride. There are tetrahydrophthalic acid, etc., and these can be used together.

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, a polyhydric alcohol and a polybasic acid are charged into a reactor.

At this time, when the number of moles of polyhydric alcohol is n, the number of moles of polyvalent basic acid is added in a ratio of n + 1.

The reaction temperature is 100 ° C to 230 ° C.

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, paratoluenesulfonic acid, and tetrabutyltanate.

The polyester molecular weight of the terminal carboxyl group thus obtained is 300 to 20,000, preferably 1,000 to 7,000.

Further, those having a molecular weight distribution of MW / MN = 2 to 15 are particularly effective as a shrinking 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 mixture 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 dilaurate, tin octylate, dibutyltin oxide, stannous chloride, stannous bromide, stannous iodide, etc. It is preferable to use 50 ppm, particularly 0.1 to 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.

The 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 kratons, it is preferable that the addition amount thereof be 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%.

Further, as a method for synthesizing the shrinkage reducing agent for unsaturated polyester resin 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 was previously synthesized. A method in which a transesterification reaction is performed with a polylactone having a high degree of polymerization may be used.

Add polyesters and lactones with carboxyl groups at both ends, add catalyst and polyhydric alcohol with 3 or more valences, and set reaction temperature.
When the reaction is carried out at 160 ° C to 230 ° C, first, ring-opening polymerization of lactones occurs to form polylactone polyol.

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 temperature of the lactone polymer produced in this way is 160 ° C.
The temperature is controlled to ~ 170 ° C, and the powdery aliphatic polybasic acid anhydride is used in a powder form in an amount of 1.8 parts per 1,000 parts of the lactone polymer.
Add ~ 21 copies.

The reason for setting the addition amount of the polybasic acid anhydride in the above range is to maintain the acid value of the low-contraction agent obtained in the range of 4 to 15.

After adding the aliphatic anhydride, adjust the reaction temperature while stirring.
Keep at 160-180 ° C and react for 2 hours.

Aliphatic acid anhydride added to 1000 parts of lactone polymer
If it is less than 1.8 parts, the acid value will be less than 4 and the thickening will be slowed during SMC (sheet molding compound) production.

On the other hand, if the addition amount is more than 21 parts, the acid value exceeds 15 and the thickening during SMC production is too fast, which is not preferable.

The molecular weight of the lactone polymer thus prepared is usually 50.
It is about 0 to 10,000.

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 for unsaturated polyester resin comprising the novel lactone polymer of the present invention thus obtained is not only unsaturated polyester but also a surface modifier for epoxy resin,
It can be used extremely advantageously in many fields such as a plasticizer for thermoplastics, a pigment dispersant, a urethane pigment dispersibility improver, a paint flexibility imparting agent, and a pigment dispersant.

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.

Synthetic Example 1. In a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a condenser with a dehydration tube, 1095 parts of adipic acid, 1,6
-Hexanediol 767 parts, tetrabutyl titanate 0.0
When 02 parts were charged and reacted in a nitrogen atmosphere, dehydration started from 140 ° C, the temperature also increased to 220 ° C as the dehydration progressed, and the reaction was continued until the dehydration amount reached 234 parts. Acid value (KOHmg / g ) 70.2, average molecular weight (polystyrene conversion) MN = 2480 polyester was obtained.

Separately, in a similar device, polyester 300 obtained by the above reaction
Part, ε-caprolactone 1677 part, Ventaerythritol
23 parts, tetrabutyl titanate 0.002 parts were charged, 210 ° C
After reacting for 10 hours at room temperature, 4 parts of maleic anhydride was additionally charged and further reacted at the same temperature for 2 hours. Acid value (KOHmg / g) 14.9, hydroxyl value (KOHmg / g) 18.6, average molecular weight ( A lactone polymer having a polystyrene-converted MN of 5760 was obtained.

Synthesis Example 2. In a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a condenser with a dehydration tube, 1392 parts of adipic acid, 954 parts of diethylene glycol, and 0.002 parts of tetrabutyl titanate.
When parts were charged and reacted in a nitrogen atmosphere, dehydration started from 140 ° C, the temperature also increased to 220 ° C as the dehydration progressed, and the reaction was continued until the dehydrated amount reached 328 parts. Acid value (KOHmg / g ) 23.8, average molecular weight (polystyrene conversion) MN = 6900 polyester was obtained.

Separately, in a similar device, polyester 825 obtained by the above reaction
Part, ε-caprolactone 4573 part, pentaerythritol
Charge 102 parts, 0.02 parts of tetrabutyl titanate, 210 ℃
After reacting for 10 hours at room temperature, 9 parts of succinic anhydride was additionally charged, and further reacted at the same temperature for 2 hours, the acid value (KO
A lactone polymer having a Hmg / g) 6.8, a hydroxyl value (KOHmg / g) of 28.5, and an average molecular weight (in terms of polystyrene, MN = 6240) was obtained.

Example 1. Unsaturated polyester resin obtained from maleic anhydride and isophthalic acid and 1,2-propylene glycol 35
Parts, styrene 50 parts, resin 15 parts obtained in Synthesis Example-1, t-butyl perbenzoate 1 part, MgO 1 part, calcium carbonate 20
0 parts and 4 parts of zinc stearate were mixed and stirred, and a sheet material containing 100 parts of glass fiber having a fiber length of 1 inch was produced from the paste by a sheet mold compound machine. After aging this at 40 ℃ for 1 day, 150 ℃, 100kg / c
After press molding for 3 minutes under a pressure of m ^2, a smooth plate having a uniform surface was obtained.

The linear shrinkage rate was 0.14% (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 obtained in Synthesis Example-2, t-butyl perbenzoate 1 part, calcium carbonate 180 parts, Mg0
1 part and 3 parts of zinc stearate are mixed and stirred, and the paste-like material kneaded into a glass fiber mat is coated so as to be 100 parts of glass fiber, and pressed by a roll to impregnate the glass fiber, and at 40 ° C for 1 day. It was left to stand and a sheet molding compound was obtained.

This was press molded at 140 ℃ 100kg / cm ² for 4 minutes,
A plate with a smooth surface and no warping was obtained.

The linear shrinkage was 0.122% (expansion).

Claims (1)

[Claims] 1. A lactone polymer synthesized from a polyester resin having a terminal carboxyl group synthesized from a polyhydric alcohol, a polybasic acid or an anhydride thereof, and a lactone polymer synthesized from a lactone and a polyhydric alcohol having a valence of 3 or more. A shrinkage-reducing agent for unsaturated polyester resins, characterized by reacting a basic acid anhydride.