JPH0244322B2 - - Google Patents

Description

[Detailed description of the invention]

By mixing a thermoplastic resin into an unsaturated polyester resin composition, it is possible to reduce the amount of curing shrinkage of the unsaturated polyester resin composition, and the cracks and deformation caused by curing of the unsaturated polyester resin composition are improved. I started to do that. In addition, molded products such as SMC and BMC using this method have improved dimensional accuracy and surface smoothness. However, this low shrinkage technique, as described in Japanese Patent Publication No. 46-14541, results in an optically inhomogeneous appearance after curing, and on a microscopic scale it actually gives an inhomogeneous structure. For this reason, when the amount of curing shrinkage is reduced to a practically sufficient level, the cured product has the disadvantage of becoming brittle. In addition, thermoplastic resins with a large low shrinkage effect are generally hard at room temperature, and when these thermoplastic resins are mixed, even if they are dissolved in the unsaturated polyester resin composition before curing, the unsaturated polyester resin composition becomes unsaturated after curing. It has a structure in which islands are precipitated in the composition, making it brittle. To compensate for this brittleness, there is a method of selecting a thermoplastic resin such as a resin or rubber that is soft at room temperature, but in this case, it is necessary to mix a large amount of resin or rubber in order to provide sufficient low shrinkage. Although the brittleness of the cured product is improved and it becomes more flexible, it also increases the price and reduces mechanical strength such as bending strength. In addition, in the composition of unsaturated polyester resin, by reducing the amount of unsaturated acid component and lowering the three-dimensional crosslinking density of unsaturated polyester resin, and by appropriately selecting the types of dibasic acid component and glycol component. Although there is a method to improve the brittleness by making the unsaturated polyester resin itself flexible, it has the same disadvantages as the above, such as a decrease in mechanical strength and the low shrinkage effect not being sufficiently exhibited. The present invention aims to reduce the shrinkage of unsaturated polyester resin compositions by incorporating such thermoplastic resins, and to prevent embrittlement by minimizing the amount of thermoplastic resins that cause brittleness. In order to maintain low shrinkage even when the amount of resin mixed in is reduced, and to impart even more flexible mechanical properties, we will try to modify the unsaturated polyester resin itself into a flexible resin with low shrinkage when cured. That is. The present invention is an unsaturated polyester having a molecular weight per double bond (Mw/C=C) of 250 or less and a weight average molecular weight of 1500 to 5000, which is obtained using maleic anhydride and/or fumaric acid and glycol as essential components. The weight average molecular weight obtained by reacting (A) with adipic acid and/or phthalic acid and glycol is
Mass ratio of 2000 to 7000 saturated polyester (B)
Modified unsaturated polyester and styrene obtained by condensation reaction with (B)/{(A)+(B)} set at 0.2 to 0.6 and modified unsaturated polyester:styrene (mass ratio) set at 4:6 to 8:2 A low shrinkage unsaturated polyester resin composition comprising: The unsaturated polyester resin composition of the present invention has less curing shrinkage than conventional unsaturated polyester resin compositions, and has a small elastic modulus and is flexible without reducing the mechanical strength of the cured product. It has characteristics. In the present invention, when the mass ratio of modified unsaturated polyester to styrene is 4:6 to 8:2, the mechanical strength, flexibility, and low shrinkage effect of the cured product are well balanced. This is preferable because it provides the best results. The above unsaturated polyester used in the present invention
(A) is a saturated dibase such as phthalic anhydride, fumaric acid, and optionally phthalic acid, phthalic anhydride, halogenated maleic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, succinic acid, adipic acid, etc. Acid, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butylene glycol, neopentyl glycol, hydrogenated bisphenol A,
It is obtained by reacting glycols such as 1,6-hexanediol, 1,4-butylene glycol, and adducts of bisphenol A and propylene oxide or ethylene oxide. In this case, the double bond 1
If the molecular weight per unit (Mw/C=C) is designed to be 250 or less, the effect of reducing shrinkage is significant, but if it exceeds 250, sufficient low shrinkage cannot be obtained. In the present invention, the molecular weight per double bond (Mw/C=C) is the molecular weight calculated from the molar composition of the acid component and glycol component used in the synthesis of unsaturated polyester, and is the molecular weight of the dibasic acid component. and the glycol component react at a molar ratio of 1:1, and the corresponding amount of water is eliminated,
The model calculation value, which ignores excess acid and glycol components, is obtained by dividing the value by the number of double bonds contained in the molecule. For example, 1.0 mol of maleic acid,
Mw/C=C of an unsaturated polyester with a charging molar composition of 1.1 mol of propylene glycol and 0.1 mol excess of propylene glycol is (98.1 x 1.0 mol x
Calculated as: 76.1 x 1.0 mol - 18.0 x 1.0 mol) ÷ 1.0 = 156. Further, the saturated polyester (B) used in the present invention is obtained by reacting adipic acid and/or phthalic acid with glycol. There are no particular restrictions on the method of synthesizing the unsaturated polyester (A) and saturated polyester (B) used in the present invention.
Manufactured by conventional synthetic methods. If necessary, an esterification promoting catalyst such as dibutyltin oxide, hydroquinone to prevent gelation, etc.
A curing inhibitor such as parabenzoquinone may be added. Unsaturated polyester (A) has a weight average molecular weight of 1500
The weight average molecular weight of the saturated polyester (B) is in the range of 2,000 to 7,000. If both are below the lower limit, the mechanical properties and shrinkage reduction effect of the cured product will be poor, and if the upper limit is exceeded, the resulting unsaturated polyester resin composition will increase in viscosity and the mechanical strength of the cured product will decrease, making it impractical. If the weight average molecular weights of both are within the above range, the mechanical properties of the cured product, the low shrinkage effect of the resin composition, the viscosity, etc. will be well balanced. Low shrinkage and flexibility can be imparted by condensation reaction of unsaturated polyester (A) and saturated polyester (B), but the charge mass ratio (B)/{(A)+( B)} is outside the range of 0.2 to 0.6, the balance between low shrinkage and mechanical strength of the cured product will be lost. The weight average molecular weight in the present invention is measured by the following measuring method. Using a high-performance liquid chromatograph, the solvent (tetrahydrofuran) is flowed at a flow rate of 1.76 ml per minute at a temperature of 38°C, and 50 μ of a tetrahydrofuran sample solution with a concentration of 64 mg/ml is injected for measurement. The column used was Hitachi Chemical Co., Ltd.; trade name Gelco R-420, R.
-430 and R440 connected in series were used. The weight average molecular weight of the sample is calculated from the relationship between the logarithm of the molecular weight and the count number of a calibration curve prepared using several types of monodisperse polystyrene standard samples. The low shrinkage unsaturated polyester resin of the present invention may be made of conventionally known thermoplastic resins such as vinyl acetate resin, acrylic resin, styrene resin, etc.
These solutions may be used in combination. In addition, fillers such as calcium carbonate and aluminum hydroxide, curing agents such as t-butyl peroxybenzoate and benzoyl peroxide, mold release agents such as zinc stearate and calcium stearate, magnesium hydroxide, oxidized It may contain a thickener such as magnesium, a fiber reinforcing agent such as glass fiber or carbon fiber, or a coloring agent such as titanium white or carbon. The resin of the present invention can be used as a resin component of SMC, BMC, etc., a resin component of FRP manufactured by a hand lay-up method, a preform mated metal die method, etc. The present invention will be explained with reference to Examples and Comparative Examples.
The curing shrinkage rate used in the examples was determined by the following measurement method. 50g of benzoyl peroxide to 50g of sample resin liquid
% solution was added, and after stirring, the mixture was poured into a test tube with a diameter of 18 mm. This test tube was immersed in a constant temperature oil bath at 80°C to harden the sample resin liquid. The curing shrinkage rate S was calculated using the following formula from the specific gravity ρ _S of this cured resin and the specific gravity ρ _R of the resin liquid at 80° C. measured using a Harvard pycnometer. S = (1/ρ _R -1/ρ _S ) x ρ _R x 100 (unit %) (1) Production of unsaturated polyester Maleic anhydride 1.0 mol, propylene glycol 1.15 molar ratio (Mw/C=C is 156 ),
Furthermore, after adding hydroquinone in an amount of 0.015% by mass based on the total mass, the mixture was reacted at 210° C. while measuring the viscosity to obtain an unsaturated polyester (A-1) having a weight average molecular weight of 1150. A part of it was reacted at 210℃ while measuring the viscosity to obtain a weight average molecular weight.
3320 unsaturated polyester (A-2) was obtained. Further, a part of the mixture was reacted at 210° C. while measuring the viscosity to obtain an unsaturated polyester (A-3) having a weight average molecular weight of 5,500. Also 0.75 mol of maleic anhydride, 0.25 mol of adipic acid
mol, propylene glycol at a ratio of 1.05 mol (Mw/C=C is 228), and furthermore, 0.015% by mass of hydroquinone was added to the total mass of the mixture and reacted at 210°C to form an unsaturated polyester (A- 4) was obtained. Furthermore, the ratio of 0.6 mol of maleic anhydride, 0.4 mol of phthalic acid, 0.45 mol of propylene glycol, and 0.6 mol of diethylene glycol (Mw/C=C is 312)
Further, hydroquinone was added in an amount of 0.015% by weight based on the total mass of the preparation, and the reaction was carried out at 220°C to obtain an unsaturated polyester (A-5) having a weight average molecular weight of 4225. (2) Production of saturated polyester Adipic acid 1.0 mol, propylene glycol
Prepared at a ratio of 1.05 mol and further added 0.05% by weight of dibutyltin oxide based on the total mass of the prepared material.
The reaction was carried out at 220°C while measuring the viscosity to obtain a saturated polyester (B-1) having a weight average molecular weight of 1108.
A part of it was further reacted at 210°C while measuring the viscosity to obtain a saturated polyester (B-2) having a weight average molecular weight of 2754. Further, a portion of the mixture was reacted at 210°C while measuring the viscosity to obtain a saturated polyester (B-3) having a weight average molecular weight of 6416. In addition, 1.0 mol of phthalic acid, 0.45 mol of propylene glycol, and 0.6 mol of diethylene glycol were charged, and dibutyltin oxide was added in an amount of 0.05% by weight based on the total mass of the ingredients, and the mixture was reacted at 220°C. B-4) was obtained. The following explanation will be made using these unsaturated polyesters and saturated polyesters. The composition of Example 1 is an unsaturated polyester (A-
2) and saturated polyester (B-2) mass ratio
(B) / (A) + (B) = 0.25, and the condensation reaction was carried out at 200°C for about 1 hour. The resulting modified unsaturated polyester styrene solution had a curing shrinkage rate of 4.5%,
The bending strength of the cured product is 8.5Kg/ ^mm2 , and the bending modulus is 160.
Kg/ ^mm2 . In addition, the bending strength and bending elastic modulus are
This is a value measured according to JISK7023. Comparative example 1
The composition used only unsaturated polyester (A-2) and had a large curing shrinkage rate of 8.1%.
The composition of Comparative Example 2 had the same charge mass ratio (B)/
Although {(A)+(B)}=0.25, it was merely mixed without performing a condensation reaction, and the bending strength of the cured product was as low as 6.9 Kg/mm ² , making it unsuitable for practical use. The compositions of Examples 2 and 3 are unsaturated polyesters (A-2) and (A-2) with Mw/C=C of 228 and 156.
A modified unsaturated polyester obtained by reacting B-4) with a saturated polyester (B-4) for about 1 hour is used. The composition of Comparative Example 3 uses a modified unsaturated polyester obtained by similarly reacting an unsaturated polyester (A-6) with Mw/C=C of 312 with a saturated polyester (B-4) for about 1 hour. It is. The compositions of Examples 2 and 3 are superior to the composition of Comparative Example 3 in that they have smaller curing shrinkage rates.

[Table] Stell resin composition.

[Table] Stell resin composition.
The compositions of Comparative Examples 4 and 5 are unsaturated polyesters.
Examples in which the weight average molecular weights of (A) and saturated polyester (B) are less than the lower limit or higher than the upper limit of the range of the present invention are used, and the curing shrinkage rate is large and the bending strength of the cured product is small. On the other hand, the composition of Example 4 having a weight average molecular weight within the range of the present invention has excellent curing shrinkage and bending strength of the cured product. The composition of Comparative Example 6 includes unsaturated polyester (A),
The curing shrinkage rate is large when the charged mass ratio of saturated polyester (B) is less than the lower limit of the present invention, and the composition of Comparative Example 7 has unsaturated polyester (A) and saturated polyester (B).
Since the charged mass ratio exceeds the upper limit of the present invention, the bending strength of the cured product is low, and both are impractical.

【table】

[Table] A resin composition.

【table】

[Table] A resin composition.
The cured product obtained from the low-shrinkage unsaturated polyester resin composition of the present invention has a reduced curing shrinkage rate while maintaining mechanical strength and flexibility equal to or higher than those of conventional unsaturated polyester resin compositions. .

Claims (1)

[Claims] 1 Molecular weight per double bond obtained using maleic anhydride and/or fumaric acid and glycol as essential components is 250 or less, and the weight average molecular weight is 1500 ~
5,000 unsaturated polyester (A) and a saturated polyester (B) with a weight average molecular weight of 2,000 to 7,000 obtained by reacting adipic acid and/or phthalic acid with glycol at a mass ratio (B)/{( A) + (B)} from 0.2 to
A low shrinkage unsaturated polyester resin composition comprising a modified unsaturated polyester obtained by a condensation reaction of 0.6 and styrene in a modified unsaturated polyester:styrene (mass ratio) of 4:6 to 8:2.