JPH06228254A - Resin composition for coating inner surface of mold - Google Patents

Abstract

PURPOSE:To provide the subject composition comprising a specific unsaturated polyester, a carboxyl group-free ethylenically unsaturated monomer, and a carboxyl group-containing ethylenically unsaturated monomer and excellent in adhesivity, mold release property, etc. CONSTITUTION:The objective composition comprises 50-80 pts.wt. of an unsaturated polyester (preferably using isophthalic acid, etc.), 20-50 pts.wt. of a carboxyl group-free ethylenically unsaturated monomer (preferably using styrene, alpha-methylstyrene, etc.), and 0.5-30 pts.wt., preferably 0.5-10 pts.wt., of a carboxyl group-containing ethylenically unsaturated monomer (preferably using acrylic acid, methacrylic acid, etc.).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition capable of forming a surface coating layer of a molded article in a mold, and more specifically,
The present invention relates to an unsaturated polyester-based resin for in-mold coating which has good adhesion to a sheet molding compound (SMC) or bulk molding compound (BMC) substrate.

[0002]

2. Description of the Related Art Fiber-reinforced composite materials (FRP) are used in a very wide range of fields because they are lighter in weight than metal materials, have excellent corrosion resistance, and have high strength. F
There are many molding methods for molding RP, such as a hand lay-up method, a spray-up method, a press molding method, an injection molding method, a filament winding method, an SMC method, a BMC method, a pultrusion method, and a premix method. In the case of the hand layup method and spray up method, F
For the purpose of forming a protective film by preventing surface defects such as bubbles generated during molding of RP, gel coating is often performed before molding of FRP. On the other hand, in the case of other molding methods, after the FRP is molded, the treatment with the filling agent or the paint undercoat agent is performed before the final paint coating step.

In order to eliminate such a complicated process,
An in-mold coating method has been devised in which a material capable of forming a surface coating film is injected into a mold before demolding the FRP.
It is effectively used in molding methods such as the BMC method. As the resin composition for in-mold coating, a two-pack type urethane composition has been used before, but in recent years, the mainstream has shifted to a one-pack type using a vinyl ester resin or the like, and various inventions have been disclosed. (JP-A-60-23443, JP-A-60-221)
No. 437, No. 60-47016, JP-A-1-1263.
16 publication).

However, the vinyl ester resin contains S
There is a problem that the adhesiveness to MC and BMC is poor, and it has not been possible to obtain satisfactory adhesiveness with conventional resin compositions for in-mold coating. Further, when forming a deep-drawing molded product, there is a problem that the mold releasability from the mold deteriorates and the workability deteriorates.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a SM
It is an object of the present invention to provide a one-component type in-mold coating resin composition which is excellent in adhesion to C and BMC and is also excellent in mold releasability from a mold.

[0006]

The constitution of the present invention for achieving the above object is such that the resin composition for in-mold coating has an acid value of 1 or less.
50 to 80 parts by weight of the following unsaturated polyester is added to the ethylenically unsaturated monomer 20 having no carboxyl group.
The gist of the present invention is to add 50 parts by weight to 0.5 to 30 parts by weight of an ethylenically unsaturated monomer having a carboxyl group.

[0007]

The unsaturated polyester used in the present invention is obtained by polycondensing an unsaturated polybasic acid such as maleic acid or fumaric acid or an acid anhydride thereof with a polyol. And having an acid value of 1 or less. As the polyol, ethylene glycol, diethylene glycol,
Examples include propylene glycol, neopentyl glycol, hydrogenated bisphenol A, butylene glycol, propylene oxide or ethylene oxide adduct of bisphenol A, and the like. If desired, a saturated polybasic acid such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, or het acid, or an acid anhydride thereof may be mixed with the unsaturated polybasic acid.

As a preferred unsaturated polyester, isophthalic acid, terephthalic acid or a mixture of both is used as the saturated polybasic acid, and propylene glycol, neopentyl glycol, hydrogenated bisphenol A, butylene glycol or bisphenol A is used as the polyol. An example is one in which one or more of propylene or ethylene oxide adduct is used and polycondensed in the presence of excess polyol. An epoxy-modified unsaturated polyester obtained by reacting a terminal carboxyl group of the unsaturated polyester with glycidyl (meth) acrylate is also preferably used in the present invention.

When an unsaturated polyester having an acid value of more than 1 is used, the adhesion is relatively good, but when molding a molded product having an upright surface such as a deep-drawn molded product, it is released from the mold. Becomes difficult and the workability deteriorates, which is not preferable.

Examples of the ethylenically unsaturated monomer having no carboxyl group added to the above unsaturated polyester include styrene, α-methylstyrene, chlorostyrene, vinyltoluene, p-methylstyrene, divinylbenzene and (meth) acryl. Examples thereof include acid alkyl esters, which can be used alone or in combination. It is preferable that 20 to 50 parts by weight of the ethylenically unsaturated monomer having no carboxyl group is blended with 80 to 50 parts by weight of the unsaturated polyester. If the amount of the monomer is less than 20 parts by weight, the viscosity becomes high and injection becomes difficult, or the water resistance is deteriorated. If the amount of the monomer is more than 50 parts by weight, cracking occurs during molding, which is not preferable.

Examples of the ethylenically unsaturated monomer having a carboxyl group used in the present invention include acrylic acid, methacrylic acid, and monoesters of maleic acid and fumaric acid, which may be used alone or in combination. it can. The carboxyl group-containing ethylenically unsaturated monomer is preferably added in an amount of 0.5 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, based on 50 to 80 parts by weight of the unsaturated polyester.

The method for adding the ethylenically unsaturated monomer containing a carboxyl group may be such that the ethylenically unsaturated monomer having no carboxyl group is premixed and the unsaturated polyester is dissolved in this mixed monomer. May be added to.

The role of the ethylenically unsaturated monomer having no carboxyl group in the present invention is to adjust the viscosity of the resin composition for in-mold coating before curing and to perform three-dimensional curing reaction by radical polymerization with unsaturated polyester. The carboxyl group-containing monomer is SMC or BM.
It is useful for improving the adhesion with C molded products.

The resin composition for in-mold coating in the present invention is
It is obtained by mixing the above essential components by a known and conventional method,
If necessary, pigments, dyes, fillers, antioxidants,
A general-purpose additive such as a release agent, a polymerization initiator, a polymerization inhibitor, or a polymerization accelerator may be added. The composition of the present invention thus obtained exhibits good adhesion to a substrate used for SMC, BMC and the like and is also excellent in mold releasability from a mold.

As a method for coating the surface of the SMC or BMC molded product, the conventionally used method can be applied as it is. For example, SMC and BMC are heated and compression molded by a conventional method, the press pressure is removed or reduced before the molding material is completely cured, and the resin composition for in-mold coating of the present invention is injected and injected at high pressure, and then, It is possible to employ a method in which the composition is heated and compressed to flow the composition onto the surface of the molded article to cure the composition, and the like. The curing temperature is 90 to 160 ° C., and the curing time is 0.
5 to 10 minutes is preferable. The thickness of the coating layer is appropriately selected according to the application, but is preferably about 20 to 500 μm. Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these.

[0016]

EXAMPLES Reference Example 1 Propylene glycol 810 g and isophthalic acid 664 g
Esterification reaction at 185 ° C in an inert gas stream to give an acid value of 3
After esterification to 0, 585 g of maleic anhydride was added and the esterification was proceeded to 200 ° C. until an acid value of 22 was obtained to obtain unsaturated polyester (1). Hydroquinone (0.5 g) and styrene (1300 g) were mixed and dissolved in 1700 g of this unsaturated polyester (1), 114 g of glycidyl methacrylate and 9.9 g of triethylamine were added, and the mixture was reacted in an air stream at 115 ° C. for 2 hours to give an acid value of 0.
Viscosity 1 at 10 poise (B type viscometer rotor # 3, 60 rpm
) Epoxy-modified unsaturated polyester styrene solution (hereinafter this solution is referred to as unsaturated polyester resin (1))
Got

Reference Example 2 1700 g of unsaturated polyester (1) obtained in Reference Example 1
0.5 g of hydroquinone and 1300 g of styrene were mixed and dissolved in, and a styrene solution of an unsaturated polyester having an acid value of 13 and a viscosity of 9 poise (B type viscometer, rotor # 3, 60 rpm) (hereinafter, this solution is compared with an unsaturated polyester resin ( 1)
I got).

Reference Example 3 1824 g of ethylene oxide adduct of bisphenol A, 456 g of propylene glycol, 664 g of isophthalic acid and 0.8 g of dibutyltin oxide were added to 1 in an inert gas stream.
After the esterification reaction at 85 ° C to an acid value of 30, 585 g of maleic anhydride was added, the esterification reaction proceeded at 200 ° C, and when the acid value became 1, the reaction was stopped, and the unsaturated polyester (2) Got This unsaturated polyester (2) 2
Hydroquinone 1.0g and styrene 23 in 700g
Mix and dissolve 20g, acid value 0.8, viscosity 6 poise (B
A viscometer type rotor, rotor # 3, 60 rpm) was used to obtain a styrene solution of unsaturated polyester (hereinafter this solution is referred to as unsaturated polyester resin (2)).

Reference Example 4 100 parts by weight of an iso type unsaturated polyester (A) (hereinafter,
Parts by weight are omitted), t-butyl perbenzoate 1 part, aluminum hydroxide 300 parts, zinc stearate 4 parts, magnesium oxide 1 part, parabenzoquinone 0.0
BMC was manufactured by kneading 1 part and 45 parts of glass fiber (6 mm length) with a kneader.

Examples 1-5 and Comparative Examples 1-5 Unsaturated polyester resins (1) produced in Reference Examples 1-3
(2) and the comparative unsaturated polyester resin (1) were used as resin compositions for in-mold coating having the compositions shown in Table 1, and BMC produced in Reference Example 4 was molded and in-mold coated under the following conditions. Mold: 400 × 250 × 300 mm box Mold temperature (up / down): 135 ° C./130° C. molding pressure: 75 kg / cm ² BMC thickness: 5 mm coating film thickness: 100 μm primary curing time: 250 seconds (mold Time until injection of resin composition for inner coating) Composition injection pressure; 300 kg / cm ² secondary curing time; 200 seconds (time from completion of composition injection to mold opening)

With respect to the molded article coated in the mold under the above-mentioned conditions, the adhesiveness in the normal state and after immersion in water on one side at 90 ° C. for 500 hours was evaluated by a cross-cut test, and also shown in Table 1. The cross-cut test was performed according to JIS K5400. Also, the releasability of the molded product from the mold is ◯: good. Δ: There was a problem that minute cracks were generated on the coated surface. X: Mold release was difficult, and cracking occurred in the molded product when the mold was forcibly released. It was evaluated in 3 stages according to the standard.

[0022]

[Table 1]

[0023]

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a resin composition for in-mold coating, which has very good adhesion such that it does not peel off from the surface of a BMC molded product at all even under the severe condition of one-sided water immersion at 90 ° C. for 500 hours. I was able to provide it. Also for deep-formed products such as bathtubs, a resin composition for in-mold coating that can provide a molded product having good releasability from a mold while maintaining good adhesion with a BMC molded product is obtained. It was

Claims (1)

[Claims] 1. An unsaturated polyester 50 having an acid value of 1 or less.
.About.80 parts by weight with 20 to 50 parts by weight of an ethylenically unsaturated monomer having no carboxyl group and 0.5 to 30 parts by weight of an ethylenically unsaturated monomer having a carboxyl group. A resin composition for in-mold coating.