JPH11315198A - Production of low-shrinkage unsaturated polyester resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a low-shrinkage unsaturated polyester resin composition that can reduce the man-hour for this resin production and can shorten its manufacturing time in the production of low-shrinkage polyester resin composition with excellent low shrinkage, dimensional stability and surface smoothness by using polystyrene beads as a low-shrinkage agent. SOLUTION: When a low-shrinkage unsaturated polyester resin composition is produced by formulating (A) an unsaturated polyester, (B) an α,β-ethylenically unsaturated monomer, and (C) a low shrinkage agent, polystyrene beads having particle sizes of <=1 mm are used as (C) a low-shrinkage agent. The formulation rate of the component (A) is preferably 40-70 wt.% based on the total weight of the component (A) + the component (B), and the formulation rate of the component (C) is preferably 2-20 wt.% based on the whole amount of the components (A), (B) and (C).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a low-shrinkable unsaturated polyester resin composition using polystyrene beads as a low-shrinkage agent.

[0002]

BACKGROUND OF THE INVENTION Generally, unsaturated polyester resins
The so-called low-shrinkage agent-mixed unsaturated polyester resin composition which has a cured volumetric shrinkage of 10% and which is mixed with a thermoplastic resin as a low-shrinkage agent shows an extremely small cured volumetric shrinkage, and shows a conventional unsaturated volume shrinkage. Less occurrence of cracks and deformation due to curing than polyester resin. Also, by using this unsaturated polyester resin mixed with a low shrinkage agent as an unsaturated polyester resin molding material typified by sheet molding compound (SMC) and bulk molding compound (BMC), the dimensional accuracy and surface smoothness of the molded product Etc. came to be improved.

As the thermoplastic resin used in the unsaturated polyester resin composition mixed with a low shrinkage agent, polystyrene which is easily available and inexpensive is widely used.
Polystyrene is generally in the form of pellets having a size of about 2 to 3 mm. If the polystyrene is left as it is, its solubility in SMC and BMC compounds is poor. Therefore, it is blended as a solution of α, β-ethylenic monomer.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a low-shrinkage polyester resin composition using polystyrene beads as a low-shrinkage agent. An object of the present invention is to provide a method capable of producing a low-shrinkable unsaturated polyester resin composition having low shrinkage, dimensional stability and surface smoothness.

[0005]

The present invention relates to a low-shrinkable unsaturated polyester comprising (A) an unsaturated polyester, (B) an α, β-ethylenically unsaturated monomer and (C) a low-shrinkage agent. The present invention also relates to a method for producing a resin composition, wherein (C) polystyrene beads having a particle size of 1 mm or less are used as a low-shrinkage agent.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The unsaturated polyester of the component (A) used in the present invention is not particularly limited, and the unsaturated polyester contains an α, β-unsaturated polybasic acid or an anhydride thereof as an essential component. It is obtained by reacting a polyhydric alcohol with other basic acid components.

[0007] α, which is a raw material for the synthesis of unsaturated polyester,
As the β-unsaturated polybasic acid or its anhydride, for example,
α, β-Unsaturated dibasic acids or anhydrides thereof, for example, maleic acid, fumaric acid, itaconic acid, citraconic acid, anhydrides thereof and the like. These may be used alone or in combination of two or more.

As the polybasic acid component, in addition to α, β-unsaturated polybasic acids or anhydrides thereof, in order to control the concentration of unsaturated groups and to impart properties such as flexibility and heat resistance. ,
It is preferable to use a saturated polybasic acid or its anhydride in combination. At this time, the use ratio of the α, β-unsaturated polybasic acid or its anhydride is preferably at least 40 mol% of the polybasic acid component. When the use ratio of the α, β-unsaturated polybasic acid or its anhydride is less than 40 mol%, the strength of the obtained molded article tends to gradually decrease. From this, the use ratio of the α, β-unsaturated polybasic acid or its anhydride is preferably 45 to 80 mol%, and 50 to 7 mol%.
It is particularly preferred that it is 0 mol%.

The saturated polybasic acids or anhydrides to be used in combination include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, Hexahydrophthalic acid, hexahydrophthalic anhydride, glutaric acid, adipic acid, sebacic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, dimer acid, succinic acid, azelaic acid, rosin-maleic acid adducts, etc. Can be These may be used alone or in combination of two or more.

Polyhydric alcohols, another raw material for the synthesis of unsaturated polyesters, include ethylene glycol,
Diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,6-
Hexanediol, neopentyl glycol, 1,4-
Examples include dihydric alcohols such as cyclohexanediol and hydrogenated bisphenol A; trihydric alcohols such as glycerin and trimethylolpropane; and tetrahydric alcohols such as pentaerythritol. These may be used alone or in combination of two or more.

The polybasic acid component and the polyhydric alcohol are preferably used in an equivalence ratio of 1 to 1.3 when the polybasic acid component is set to 1;
More preferably, it is used in the range of 1.05 to 1.05. When the polyhydric alcohol decreases, the molecular weight of the resulting unsaturated polyester tends to decrease, and when the polyhydric alcohol increases, the acid value decreases and the progress of thickening by the thickener tends to be slow.

The method for producing the unsaturated polyester can be a conventionally known method. For example, the reaction proceeds while a polybasic acid component and a polyhydric alcohol component are subjected to a condensation reaction, and condensed water generated when both components react is removed out of the system. The removal of the condensed water out of the system is preferably carried out by natural distillation or vacuum distillation by passing an inert gas. To promote the distillation of condensed water, toluene,
A solvent such as xylene can be added to the system as an azeotropic component. The progress of the reaction can be generally known by measuring the amount of distillate generated by the reaction, quantifying the functional group at the end, measuring the viscosity of the reaction system, and the like.

The temperature of the reaction is preferably 150 ° C. or higher, and the reaction is preferably carried out while passing an inert gas such as nitrogen or carbon dioxide in order to prevent a side reaction due to oxidation.

For this reason, as the reaction apparatus, those made of glass, stainless steel or the like are selected, and a stirrer, a fractionating apparatus for preventing distillation of the alcohol component due to azeotropic distillation of water and the alcohol component, and a reaction system are used. It is preferable to use a heating device for increasing the temperature, a temperature control device for the heating device, a reaction device provided with a device for blowing an inert gas such as nitrogen, and the like.

The component (B) used in the present invention, α, β-
There is no particular limitation on the ethylenically unsaturated monomer, for example, styrene, chlorostyrene, divinylbenzene, tert-butylstyrene, styrene derivatives such as styrene bromide, methyl methacrylate, ethyl methacrylate, ethyl acrylate, acrylic Examples thereof include alkyl esters of methacrylic acid or acrylic acid such as butyl acrylate, hydroxyalkyl esters of methacrylic acid or acrylic acid such as ethyl β-hydroxymethacrylate and ethyl β-hydroxyacrylate, diallyl phthalate, acrylamide, and phenylmaleimide. Polyfunctional methacrylic acid or acrylic acid esters such as ethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and trimethylolpropane trimethacrylate can also be used.

As the polystyrene beads having a particle diameter of the component (C) of 1 mm or less, for example, polystyrene beads obtained by suspension polymerization of styrene are preferably used. Available as an extraordinary item.

The particle size of the polystyrene beads is 1 mm or less, preferably 0.71 mm or less, that is, beads passing through 22 mesh. When it is 1 mm or less, especially 0.71 mm or less, even when it is used by dissolving it in an α, β-ethylenically unsaturated monomer in advance, it is blended with other components to obtain a low-shrinkable unsaturated polyester resin composition. , It easily dissolves and exerts the function as a low shrinkage agent. If the particle size is too large, it takes a long time to dissolve in the α, β-ethylenically unsaturated monomer in advance, and sufficiently dissolves when blended with other components to form a low-shrinkable unsaturated polyester resin composition. And the function as a low shrinkage agent may not be exhibited. The effect of the present invention is particularly remarkable when a low-shrinkable unsaturated polyester resin composition is prepared by mixing polystyrene beads together with other components without previously dissolving them.

The polystyrene beads are converted to α and β components (B).
-When used as a solution of ethylenically unsaturated monomers,
The blending ratio of (C) to the total amount of the components (B) and (C) is preferably 20 to 50% by weight, and more preferably 25 to 45% by weight. If the amount is less than 20% by weight, the mechanical strength of the obtained molded article decreases. If the amount exceeds 50% by weight, SMC, BMC
The workability at the time of compounding becomes worse.

When polystyrene beads are blended as a solid, they are dissolved by blending together with a filler such as calcium carbonate when blending the compound of SMC and BMC. The preferable mixing ratio of the filler is preferably 100 to 200 with respect to the total amount of the components (A), (B) and (C).
% By weight.

In the present invention, the mixing ratio of the component (A) to the total amount of the unsaturated polyester (A) and the α, β-ethylenically unsaturated monomer (B) is preferably from 40 to 70.
(C) relative to the total amount of (C) of the above components (A) and (B).
The compounding ratio of the components is preferably 2 to 20% by weight, more preferably 5 to 15% by weight. If the amount of the component (A) is less than 40% by weight based on the total amount of the components (A) and (B), the mechanical strength of the obtained molded article tends to decrease.
If it exceeds 0% by weight, poor curing tends to occur. If the blending amount of (C) is less than 2% by weight based on the total amount of the components (A), (B) and (C), the curing shrinkage tends to increase, and if it exceeds 20% by weight, the molded article obtained Tends to decrease in mechanical strength.

The low-shrinkable unsaturated polyester resin composition of the present invention is used by adding a filler, a curing agent, a polymerization inhibitor, a thickener, a release agent, a reinforcing fiber, a colorant, and the like, if necessary. can do.

As the filler, silica sand, calcium carbonate,
Examples include inorganic fillers such as talc and clay, and organic fillers such as wood powder, polyethylene powder, and pulverized products of various FRP molded products.

The amount of the filler used depends on physical properties such as the strength of the molded article,
Determined in consideration of the viscosity and fluidity of the unsaturated polyester resin composition, the unsaturated polyester (A) and α,
10 to the total amount of β-ethylenically unsaturated monomer (B)
The content is preferably 0 to 200% by weight, particularly preferably 105 to 200% by weight.
Preferably, it is 150% by weight. If the amount of the filler is too small, sedimentation may occur, and if the amount of the filler is too large, viscosity tends to be high and stirring tends to be difficult. It is preferable to use 60 to 100% by weight of heavy calcium carbonate having a particle size of 0.08 to 1.0 μm among the fillers.

Examples of the curing agent include ketone peroxides, peroxydicarbonates, hydroperoxides, diacyl peroxides, peroxyketals, dialkyl peroxides, peroxyesters, and alkyl peresters. No. Since the amount of the curing agent affects not only the molding cycle but also the preservability of the material, color unevenness, and the like, it is determined according to each. From the viewpoint of the preservability of the material and the molding cycle, the content is preferably 0.5 to 5% by weight based on the total amount of the unsaturated polyester (A) and the α, β-ethylenically unsaturated monomer (B). More preferably, it is 1 to 3% by weight.

As the polymerization inhibitor, p-benzoquinone,
Naphthoquinone, tolquinone, hydroquinone, mono-t
-Butylhydroquinone, dibutylhydroxytoluene and the like. The polymerization inhibitor is preferably used in an amount of 0.5% by weight or less based on the total amount of the unsaturated polyester (A) and the α, β-ethylenically unsaturated monomer (B). When a curing agent is blended, the content of the curing agent is 0.1% for storage stability.
It is preferred that the content is not less than 05% by weight.

As the thickener, magnesium oxide, magnesium hydroxide, potassium oxide, potassium hydroxide and the like are used, and generally, magnesium oxide is used. The amount of the thickener is determined according to the workability of the molding material, and is 0.5 to the total amount of the unsaturated polyester (A) and the α, β-ethylenically unsaturated monomer (B). ~ 5% by weight
And more preferably 0.7 to 2% by weight. If the amount of the thickener is too small, the viscosity of the resin composition may not increase. On the other hand, if the amount of the thickener is too large, the viscosity may be too high to control.

As the release agent, zinc stearate, calcium stearate and the like are used. The amount of the release agent is preferably 1 to 10% by weight, more preferably 2 to 10% by weight, based on the total amount of the unsaturated polyester (A) and the α, β-ethylenically unsaturated monomer (B). 4% by weight. If the amount of the release agent is too small, the molded product may stick to the mold, making it difficult to remove the molded product, and may cause cracks or the like in the molded product. Also,
If the release agent is too large, the molded article strength tends to decrease.

The unsaturated polyester resin composition of the present invention may further contain a reinforcing fiber to obtain a fiber-reinforced molding material. SMC, BMC as fiber reinforced materials
Etc.

As the reinforcing fibers, glass fibers, carbonate fibers, aramid fibers, polyvinyl alcohol fibers and the like can be used, and glass fibers are generally used. These reinforcing fibers are used in the form of continuous fibers, woven fabrics, non-woven fabrics, etc., and roving-like fibers having an appropriate length (preferably 20 to 30 mm for SMC, BMC
In the case of (1), it is preferable to use one cut to 6 to 15 mm).

In preparing the fiber reinforced material, the amount of the reinforcing fiber used depends on the required strength, but the total amount of the unsaturated polyester (A) and the α, β-ethylenically unsaturated monomer (B) Is preferably 15 to 35% by weight.

The method of molding a fiber-reinforced molded article (FRP molded article) using the unsaturated polyester resin composition is not particularly limited, but examples thereof include an open mold such as a hand lay-up method, a spray-up method, and a centrifugal molding method. Molding,
Injection molding, compression molding, casting molding, transfer molding,
Extrusion molding, back molding, cold press molding, RT
Examples include closed molding such as M molding, resin injection molding, and matched metal die molding, and continuous molding can also be performed.

The above-mentioned fiber-reinforced molding materials, for example, SMC and BMC, are each used in a conventional SMC manufacturing apparatus or BM.
It can be manufactured using a C manufacturing apparatus.

In the case of SMC, the prepared resin composition is applied on a release film so as to have a uniform thickness, and a reinforcing fiber such as a glass fiber cut to a predetermined length is uniformly sprayed thereon. Further, another film coated with the blended resin composition thereon is overlapped so that the dispersed reinforcing fibers are sandwiched by the blended resin composition, and this is wound up in a roll, and ripened as necessary. To form a sheet-shaped molding material. When a thickener is added, it is preferable to heat the mixture to a temperature of room temperature to 60 ° C. for aging.

As the release film, a polyethylene film, a polypropylene film or the like can be used.

In the case of BMC, reinforcing fibers are mixed with the unsaturated polyester resin composition described above, but there is no particular limitation on the mixing order of the components used in these.

The viscosity of the fiber-reinforced molding material is preferably adjusted so as to be 1,000 to 160,000 Pa · s at 40 ° C. If the viscosity is too low, scumming is likely to occur on the surface of the molded article, and if the viscosity is too high, the mold clamping time will be long and the molding cycle will tend to be long. The viscosity of the fiber reinforced molding material is 30
It is more preferably adjusted to be 000 to 150,000 Pa · s, and 60,000 to 120,000 Pa · s.
It is particularly preferred that the adjustment be made so that However,
The optimum viscosity of the fiber-reinforced molding material is determined by the molding. The viscosity of the fiber-reinforced molding material can be adjusted by the amount of the thickener and the aging conditions.

Such a sheet-like molding material is molded by compression molding, transfer molding, or the like, and has a wide range of F
An RP molded product can be obtained. Molding temperature is 70-15
It is preferable that the molding pressure is 0 ° C. and the molding pressure is 0.1 to 10 MPa.

[0038]

EXAMPLES The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Maleic anhydride 98 was placed in a two-liter four-necked flask equipped with a stirrer, a condenser, an N ₂ gas inlet tube and a thermometer.
1 g, 761 g of propylene glycol, 106 g of diethylene glycol, and 0.28 g of hydroquinone were charged and heated to 90 ° C. in an N ₂ gas atmosphere. Thereafter, with stirring, the temperature was raised to 160 ° C. for 2 hours and 190 ° C. for 4 hours.
The temperature was raised to ° C. 210 ° C over 4 hours with further stirring
The reaction was proceeded by keeping the temperature as it was, and the acid value was periodically measured.When the acid value reached 27 mgKOH / g, the mixture was rapidly cooled.
An unsaturated polyester was obtained. 60 parts by weight of the unsaturated polyester was dissolved in 40 parts by weight of the styrene monomer to obtain an unsaturated polyester resin (I). Table 1 shows the unsaturated polyester resin (I) and the polystyrene for polystyrene foam discarded as an extra-fine particle having a particle size of 0.71 mm or less (D) through a 22-mesh standard sieve. By mixing, an SMC having a polyethylene terephthalate film on both sides was prepared by a conventional method, and 40
After standing in the air at a temperature of 3 ° C. for 3 days, a flat plate mold (250 mm × 50
0 mm) at a molding temperature of 140 ° C., a molding time of 10 minutes and a molding pressure of 100 kg / cm ² to form a sheet-like molded product having a thickness of 3 mm. The linear shrinkage, surface smoothness, and flexural strength of the obtained molded product were measured by the following methods, and the results are shown in Table 1.

(1) Linear shrinkage: (l ₀ -l) × 100 /
l ₀ [%] (where l ₀ is the dimension in the length direction of the mold, and l is the dimension in the length direction of the molded product). (2) Surface smoothness: Expressed as an index (6 inch SN value) measured for a length of 6 inches using a surface analyzer manufactured by Budd Corp., USA. The smaller the 6-inch SN value, the better the surface smoothness. (3) Flexural strength: measured according to JIS K-6911.

Example 2 Particle size of polystyrene for polystyrene foam discarded as an extraordinary product and having a particle size of 0.5 mm or less (30 mm or less) passed through a 30-mesh standard sieve was used according to the formulation shown in Table 1. An SMC was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Of polystyrene for polystyrene foam, which is discarded as an extraordinary particle size, 900 g having a particle size of 0.71 mm or less (D) through a 22-mesh standard sieve was stirred into 2,100 g of styrene. The resulting mixture was mixed well to obtain a polystyrene solution (II). It took 30 minutes to completely dissolve. Using the unsaturated polyester resin (I) and the polystyrene solution (II), SMC was prepared according to the formulation shown in Table 1, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 1 Of the polystyrene for polystyrene foam, which was discarded as an extraordinary particle size, passed through a 10-mesh standard sieve, and had a particle size of 0.71 to 0.71 remaining on the 22-mesh standard sieve.
Using a 1.7 mm (F) with the formulation shown in Table 1, S
An MC was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 Polystyrene (F) used in Comparative Example 1 was dissolved in styrene in the same manner as in Example 3 to obtain a polystyrene solution (III). It took 1.5 hours for complete dissolution. Using the unsaturated polyester resin (I) and the polystyrene solution (III), SMC was prepared according to the formulation shown in Table 1, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 3 Polystyrene (G), 2 to 3 mm granules (denkastyrol QP-2-301 (polystyrene, trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.)) were dissolved in styrene in the same manner as in Example 3, and a polystyrene solution ( IV) was obtained. It took 2.5 hours for complete dissolution. An SMC was prepared using the unsaturated polyester resin (I) and the polystyrene solution (IV) according to the formulation shown in Table 1,
The same evaluation as in Example 1 was performed. The results are shown in Table 1.

[0046]

[Table 1]

From the results in Table 1, it can be seen that, in Examples 1, 2 and 3 in which polystyrene for polystyrene foam having a particle size of 0.71 mm or less was discarded as a product having a particle size of extraordinary, As in Comparative Example 3 using a conventional polystyrene solution, the linear shrinkage was low, indicating that excellent surface smoothness and bending strength were obtained. In this case, the same performance can be obtained even when used as a solid or as a solution, and the dissolution time in styrene can be shortened.
If the particle size of the polystyrene exceeds 1 mm, in Comparative Example 1 where the polystyrene was used as it was, there was a bump in the SMC sheet,
The resulting molded article properties are also reduced.

[0048]

According to the process for producing a low shrinkage unsaturated polyester resin composition of the present invention, a low shrinkage unsaturated polyester resin composition having excellent low shrinkage, dimensional stability and surface smoothness can be produced. In the process, particularly in the SMC and BMC manufacturing process, the number of steps or the manufacturing time can be reduced. In addition, the cost can be reduced by using an expanded polystyrene bead having a particle size exceeding the specified value.

Claims (2)

[Claims] 1. An unsaturated polyester (A), (B) α,
In the method for producing a low-shrinkable unsaturated polyester resin composition containing a β-ethylenically unsaturated monomer and (C) a low-shrinkage agent, polystyrene beads having a particle size of 1 mm or less are used as the (C) low-shrinkage agent. A method for producing a low-shrinkable unsaturated polyester resin composition, comprising: 2. The compounding ratio of the component (A) to the total amount of the components (A) and (B) is 40 to 70% by weight,
The compounding ratio of the component (C) to the total amount of the components (A), (B) and (C) is 2 to 20% by weight.
A method for producing the low-shrinkable unsaturated polyester resin composition as described above.