JPH0689239B2 - Low shrinkage unsaturated polyester resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a low shrinkage unsaturated polyester resin composition. More specifically, the present invention relates to a low-shrinkage unsaturated polyester resin composition which can be used in a sheet molding compound (SMC) and a bulk molding compound (BMC).

(Prior Art) An unsaturated polyester resin composed of an unsaturated polyester obtained by a reaction of a polybasic acid containing an unsaturated polybasic acid with a polyhydric alcohol or an alkylene oxide and a copolymerizable monomer is useful for thermosetting. It is used in a wide range of fields as a functional resin. Especially in recent years, SM that combines glass fiber and filler
C and BMC have been developed for press molding and injection molding and are used in large quantities.

However, the unsaturated polyester resin is accompanied by large shrinkage during curing, and therefore has drawbacks such as poor dimensional accuracy of the molded product, cracking, and poor surface smoothness.

In order to improve these drawbacks, there are many methods, for example, a method in which a highly reactive unsaturated polyester resin is mixed with a thermoplastic resin such as polystyrene, polyalkylmethacrylate, polyvinyl acetate or saturated polyester (for example, Japanese Patent Publication No.
42-8,787, JP-B-46-15,431, JP-A-48-20,888,
The methods described in JP-A-48-79,889 and JP-A-52-996) have been proposed, and the fields of use of unsaturated polyester resins have been expanded.

(Problems to be Solved by the Invention) However, these conventional methods are still unsatisfactory for applications such as automobile outer panel parts in which the surface smoothness of the molded product is particularly demanding. That is, the conventional low shrinkage unsaturated polyester resin composition consisting of unsaturated polyester, copolymerizable monomer, saturated polyester,
Although it is possible to reduce the shrinkage ratio during molding or to expand it, the surface smoothness of the molded product, especially the molded product having ribs or bosses on the back surface, was insufficient.

Further, when a conventional low-shrinkage unsaturated polyester resin composition is kneaded with a filler and further impregnated into glass fiber to form SMC, the viscosity of the kneaded material (paste) with the filler becomes high, There is also a problem that the amount cannot be increased and impregnation into the glass fiber is unsatisfactory, resulting in a decrease in mechanical strength of the obtained molded product. Further, also in the case of BMC in which glass fibers are kneaded by a kneader, if the viscosity of the paste is high, the glass fibers will be more damaged, so that the mechanical strength of the obtained molded article will be reduced.

Furthermore, a fast-curing resin composition prepared by mixing a liquid polybutadiene resin having a polymerizable unsaturated bond introduced at the terminal and a saturated polyester resin into an unsaturated polyester resin composed of an unsaturated polyester and a copolymer monomer is embedded. Has been proposed as a varnish for use in the production (Japanese Patent Application Laid-Open No. 55-43,151
issue). However, when such a resin composition is used as a molded product, it has a drawback that the surface waviness is large and thus the surface smoothness is low and the surface is stained due to separation of polybutadiene. Therefore, the resin composition is SMC or BMC.
It was insufficient as a resin composition for use.

Therefore, an object of the present invention is to provide a novel low shrinkage unsaturated polyester resin composition. Another object of the present invention is to provide a low-shrinkage unsaturated polyester resin composition capable of giving a molded article excellent in flatness and mechanical strength.

(Means and Actions for Solving Problems) As a result of repeated studies in view of the above circumstances, the present inventor has combined an unsaturated polyester resin having a specific unsaturated group concentration with a specific thermoplastic resin and a liquid rubber. As a result, they have found that the above-mentioned object can be achieved, and have completed the present invention.

That is, the present invention has a number average molecular weight per double bond of 30
20 to 50% by weight of unsaturated polyester (a), which is 0 or less,
Copolymerizable monomer (b) 25-65% by weight, number average molecular weight 3,000
0 to 30,000 saturated polyester (c) 5 to 25% by weight and acid group-containing liquid isoprene rubber (d) 2 to 20% by weight (however, the sum of components (a), (b), (c) and (d)) Is 100% by weight). A low shrinkable unsaturated polyester resin composition containing 100% by weight.

The unsaturated polyester (a) used in the present invention is α, β-
It is a reaction product of an acid component consisting of an unsaturated dibasic acid or a derivative thereof, and optionally a saturated dibasic acid, and a polyhydric alcohol or an alkylene oxide.

Examples of the α, β-unsaturated dibasic acid or its derivative include maleic anhydride, maleic acid, fumaric acid, halogenated maleic anhydride, itaconic acid, citraconic anhydride, and the like. Two or more types are used.

Examples of the saturated dibasic acid include phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride and 3,6-endomethylenetetrahydrophthalic acid. Acid, sebacic acid, succinic acid, succinic anhydride, etc. can be mentioned, and 1 type (s) or 2 or more types of these are used.

Examples of the polyhydric alcohol include ethylene glycol,
Diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol-1,3, butanediol-1,4, butanediol-
2,3, neopentyl glycol, pentanediol-1,
5, Hexanediol-1,6,2,2,4-trimethylpentane, diol-1,3, glycerin, trimethylolethane, trimethylolpropane, hydrogenated bisphenol A, addition of bisphenol A and ethylene oxide or propylene oxide And the like, and one or more of these can be used.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, and epichlorohydrin.
One kind or two or more kinds can be used.

The reaction can be carried out by an ordinary method in an inert gas stream at 150 to 250 ° C, preferably 180 to 220 ° C.

The molecular weight of the unsaturated polyester (a) is not particularly limited, but the number average molecular weight is preferably in the range of 800 to 3,000. 800
If it is less than, water resistance, heat resistance, etc. may be insufficient, or SMC
In some cases, thickening due to a reaction with a metal oxide used as a thickening agent in making BMC or BMC becomes insufficient. Also 3,00
When it exceeds 0, the viscosity of the kneading paste with the filler becomes high, which may cause difficulty in forming SMC or BMC.

And the number average molecular weight per double bond of the unsaturated polyester (a) is 300 or less, preferably in the range of 150 to 260, and when it is more than 300, the effect of lowering the shrinkage becomes small and the obtained molded article is obtained. Also has a poor surface smoothness. The amount of unsaturated polyester (a) used is (a), (b),
In the range of 20 to 50% by weight, preferably 25 to 40% by weight in the total of the components (c) and (d), the effect of reducing shrinkage and the obtained molding can be obtained even if the amount is less than 20% by weight or exceeds 50% by weight. The surface smoothness of the product deteriorates.

As the copolymerizable monomer (b) used in the present invention, known ones commonly used in unsaturated polyester resins can be used, and examples thereof include styrene, chlorostyrene, α-methylstyrene, paramethylstyrene and vinyltoluene. Aromatic monomers such as divinylbenzene and diallyl phthalate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl mecrylate, and lauryl methacrylate; methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, lauryl acrylate, etc. Alkyl acrylates and the like can be mentioned, and one or two of these can be mentioned.
More than one species can be used. The usage amount is (a), (b),
The total amount of the components (c) and (d) is in the range of 25 to 65% by weight, preferably 35 to 55% by weight. If it is less than 25% by weight, the viscosity of the paste will be high and it will be difficult to make it into SMC or BMC. If it exceeds 65% by weight, the effect of reducing shrinkage will be small and the surface smoothness of the resulting molded product will be poor. Become.

The saturated polyester (c) used in the present invention is a condensate of a saturated dibasic acid as an acid component and a glycol as a polyhydric alcohol component. Examples of the saturated dibasic acid include isophthalic acid, terephthalic acid, adipic acid, succinic acid, azelaic acid, sebacic acid and the like. One or more of these can be used, and particularly adipic acid and isophthalic acid. Alternatively, it is desirable that terephthalic acid is contained in the acid component in an amount of 50 mol% or more, preferably 70 mol% or more.

Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol-1,3, butanediol-1,4, butanediol-2,
3, neopentyl glycol, pentanediol-1,5,
Pentanediol-1,6 and the like can be mentioned, and one or more of these can be used. Particularly, ethylene glycol, diethylene glycol or dipropylene glycol is 50 mol% in the polyhydric alcohol component, preferably 70 mol.
It is desirable that the content be at least mol%.

Although the molecular weight of the saturated polyester (c) is not particularly limited,
Number average molecular weight of 3,000 to 30,000, preferably 4,000 to 15,0
A value of about 00 is suitable. If it is less than 3,000, the effect of reducing shrinkage may be small, and if it exceeds 30,000, the viscosity of the paste may be high, and it may be difficult to achieve SMC or BMC. The amount of saturated polyester (c) used is
5 out of the total of components (a), (b), (c) and (d)
It is in the range of 25% by weight, preferably 7 to 20% by weight. If it is less than 5% by weight, the effect of lowering the shrinkage and the surface smoothness of the obtained molded product will be poor, and if it exceeds 25% by weight, the paste viscosity will be high and it will be difficult to achieve SMC or BMC.

The acid group-containing liquid isoprene rubber (d) used in the present invention is liquid at room temperature and has a number average molecular weight of 3,000 to 5
It is about 000, preferably about 7,000 to 30,000. Preferably, it contains an acid group having an acid value of 10 to 40, more preferably 15 to 30 in the molecule or at the terminal. By introducing an acid group, compatibility with the unsaturated polyester resin is improved, and problems such as mold fouling due to separation of the liquid isoprene rubber during molding of SMC or BMC can be minimized. Further, as a method of introducing an acid group, a copolymer of isoprene and maleic anhydride is reacted with water or an alcohol such as methanol, ethanol, isopropanol, butanols or the like, and isoprene and maleic acid or maleic acid monoester. And the like. However, it goes without saying that the present invention is not limited by the method of introducing these acid groups. The amount of the acid group-containing liquid isoprene rubber (d) used is in the range of 2 to 20% by weight, preferably 5 to 15% by weight, based on the total amount of the components (a), (b), (c) and (d). Is. 20% by weight even if less than 2% by weight
Even if it exceeds the range, the effect of lowering the shrinkage and the surface smoothness of the obtained molded product deteriorate. Further, rubber becomes solid when the molecular weight becomes large, but when solid rubber is used, the viscosity of the paste becomes high and it becomes very difficult to make it into BMC or SMC.

When converting to SMC or BMC using the resin composition of the present invention,
As the filler, for example, calcium carbonate, aluminum hydroxide, alumina, silica, clay, feldspar powder, river sand, powdered inorganic substances such as water-filling stones 0 to 400 parts by weight, preferably 100 parts by weight with respect to 100 parts by weight of the resin composition. It can be used in the range of up to 300 parts by weight, most preferably 150 to 250 parts by weight. As the reinforcing material, for example, fibers such as glass fiber, carbon fiber, aromatic polyamide fiber, vinylon fiber and the like are 0 to 400 parts by weight, preferably 10 to 300 parts by weight, and most preferably 100 parts by weight of the resin composition. Can be used in the range of 30 to 200 parts by weight.

Further, in the resin composition of the present invention, if necessary, thickening agents such as magnesium oxide and magnesium hydroxide, other known shrinkage reducing agents such as polystyrene, silane coupling agents, release agents such as calcium stearate and paraffin, etc. Agents, thixotropic agents, plasticizers, pigments and colorants, flame retardants, flame retardants and the like can be added.

The thus obtained low-shrinkage unsaturated polyester resin composition of the present invention is blended with a radical polymerization initiator and heated and pressed to be molded. As the radical polymerization initiator, t-butylperoxybenzoate, benzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, t-butyl peracetate, 2,5-dimethylhexyl-2,5-diperoxybenzoate, etc. Yes, the polymerization initiator is 0.1 per the resin composition.
The amount is 2 to 10% by weight, preferably 0.5 to 5% by weight.

In order to produce SMC using the composition, the above-mentioned filler, reinforcing material and / or thickening agent, if necessary, other shrinking agent, silane coupling agent, release agent, and other additives are added to the resin composition. Mix the agent and mold it into a sheet, 20 to 60 ℃, preferably
It can be obtained by aging at 30 to 50 ° C. for 5 to 300 hours, preferably 10 to 100 hours.

BMC is also produced by a known method by blending the resin composition with the above-mentioned additives and reinforcing materials.

(Examples) Hereinafter, examples will be described in more detail. In addition, unless otherwise specified, the parts used in the examples mean parts by weight. The number average molecular weight in the examples is high performance liquid chromatography (Japan Waters Co., Ltd.).
Manufactured by Model 201G).

Example 1 98 parts of maleic anhydride and 80 parts of propylene glycol were subjected to a condensation reaction under a nitrogen stream at 200 ° C. for 8 hours to give an acid value of 25,
The number average molecular weight is 1,500 and the number average molecular weight per double bond is 1
60 unsaturated polyesters were obtained. 60 parts of this unsaturated polyester and 0.01 part of hydroquinone were dissolved in 40 parts of styrene to obtain an unsaturated polyester resin (hereinafter referred to as UP-1).

On the other hand, 146 parts of adipic acid, 37 parts of ethylene glycol and 34 parts of propylene glycol were dehydrated and condensed under a nitrogen stream at a maximum temperature of 220 ° C to obtain a saturated polyester (hereinafter referred to as SP-1). The number average molecular weight of SP-1 was 6,500.

Next, 50 parts of UP-1, 10 parts of SP-1, 30 parts of styrene and 10 parts of liquid isoprene rubber (number average molecular weight 23,000, acid value 24) are mixed to obtain a low shrinkable unsaturated polyester resin of the present invention. A composition (hereinafter referred to as "resin composition (1)") was obtained.

To the obtained resin composition (1), 1 part of t-butylperoxybenzoate, 4 parts of zinc stearate and 200 parts of calcium carbonate were added and stirred to obtain a paste. The viscosity of this paste was 650 poise at 30 ° C. Furthermore, using an impregnating solution obtained by mixing 1.0 part of magnesium oxide with this paste, 100 parts of 25 mm long glass fibers were impregnated to form a sheet between two polyethylene sheets and aged at 40 ° C. for 40 hours, Made into SMC. This SMC was press-molded for 3 minutes in a mold of 300 mm × 300 mm in size at a temperature of 140 ° C. and a pressure of 60 kg / cm ² to obtain a flat plate molded product having a thickness of 2 mm. The waviness of this flat plate was measured and found to be 4 to 5 microns per 10 cm length. In addition, the molding shrinkage ratio of this SMC is JIS K 6911.
The expansion was 0.06% when measured based on.

Example 2 60 parts of unsaturated polyester having an acid value of 26, a number average molecular weight of 2,000, and a number average molecular weight of 240 per double bond are 240 obtained from 98 parts of maleic anhydride, 120 parts of hydrogenated bisphenol A and 40 parts of propylene glycol. , 40 parts of styrene and 0.01 part of hydroquinone are mixed, and unsaturated polyester resin (hereinafter,
This is called UP-2. ) Got.

Next, 50 parts of UP-2, 15 parts of SP-1 obtained in Example 1, 27 parts of styrene and liquid isoprene rubber (number average molecular weight 23.00
0, acid value 24) 8 parts were mixed to obtain the low shrinkable unsaturated polyester resin composition of the present invention (hereinafter referred to as the resin composition (2)
Say. ) Got.

To the obtained resin composition (2), 1 part of t-butylperoxybenzoate, 4 parts of zinc stearate and 200 parts of calcium carbonate were added and stirred to obtain a paste. The viscosity of this paste was 750 poise at 30 ° C. Further, using the impregnating liquid obtained by mixing 0.7 part of magnesium oxide with this paste, SMC was carried out in the same manner as in Example 1.

When this SMC was molded in the same manner as in Example 1, the undulation of the flat plate was 4 to 5 μm, and the molding shrinkage was
The expansion was 0.05%.

Example 3 Example 1 was repeated except that SP-1 in Example 1 was replaced with a saturated polyester (number average molecular weight 7,000) obtained from 166 parts of terephthalic acid and 108 parts of diethylene glycol.
A low-shrinkage unsaturated polyester resin composition of the present invention (hereinafter, referred to as "resin composition (3)") was obtained in the same manner as in. SMC was prepared in the same manner as in Example 1 except that the amount of magnesium oxide was 0.8 parts using this resin composition (3).
Turned into When this SMC was molded in the same manner as in Example 1, the undulation of the flat plate was 3 to 4 microns, and the molding shrinkage was 0.04% expansion.

Example 4 A saturated polyester (number average molecular weight 7,500) obtained from 146 parts of adipic acid and 108 parts of diethylene glycol (hereinafter referred to as SP-2) was used in place of SP-1 in Example 1. A low-shrinkage unsaturated polyester resin composition of the present invention (hereinafter referred to as "resin composition (4)") was obtained in the same manner as in Example 1. Using this resin composition (4), SMC was carried out in the same manner as in Example 1 except that the amount of magnesium oxide was 0.8 parts. When this SMC was molded in the same manner as in Example 1, the undulation of the flat plate was 4 to 5 μm, and the molding shrinkage was an expansion of 0.05%.

Example 5 A low-shrinkage unsaturated polyester resin composition of the present invention (hereinafter, referred to as a resin composition (hereinafter referred to as "resin composition") in the same manner as in Example 2 except that SP-2 was used in place of SP-1 in Example 2. 5).) Was obtained. Using this resin composition (5), SMC was carried out in the same manner as in Example 1 except that the amount of magnesium oxide was 0.8 part. When this SMC was molded in the same manner as in Example 1, the flat plate waviness was 4 to 5 microns,
The molding shrinkage was 0.05%.

Example 6 Example 2 was repeated except that saturated polyester obtained from 146 parts of adipic acid and 140 parts of dipropylene glycol (number average molecular weight 6,300) was used instead of SP-1 in Example 2.
In the same manner as described above, a low-shrinkage unsaturated polyester resin composition of the present invention and a flat plate molded article were obtained. The waviness of this flat plate was 5 to 6 microns, and the molding shrinkage was 0.06% expansion.

Comparative Example 1 A molded article for comparison was obtained in the same manner as in Example 1 except that the liquid isoprene rubber was not used.
The undulation of this molded product was 15 microns, and the molding shrinkage was 0.03%.

Comparative Example 2 SMC and flat plate undulations were performed in the same manner as in Example 1 except that a terminal vinyl polybutadiene having a number average molecular weight of about 2,000 (TE-2000 manufactured by Nippon Soda Co., Ltd.) was used instead of the liquid isoprene rubber in Example 1. Was 10 microns, the molding shrinkage was 0.02%, and the surface of the molded product was found to be contaminated due to the separation of polybutadiene.

Comparative Example 3 An SMC was prepared in the same manner as in Example 1 except that a solid isoprene rubber having a number average molecular weight of about 150,000 was used in place of the liquid isoprene rubber in Example 1, but the viscosity of the paste was about 1. It was 10,000 poise, and impregnation into glass fiber was impossible.

Example 7 50 parts of UP-1 obtained in Example 1 and 15 parts of SP-2 obtained in Example 4
Parts, styrene 30 parts, liquid isoprene rubber (acid value 24) used in Example 2 5 parts, t-butyl peroxybenzoate 1
Parts, calcium carbonate 300 parts, zinc stearate 5 parts, magnesium oxide 0.6 parts and glass fibers (6 mm length) 90 parts were kneaded for 2 minutes with a Banbury type kneader to obtain BMC. This BMC was molded in the same manner as in Example 1. The resulting molded product has a swell of 6 to 7 microns and a molding shrinkage of 0.06.
% Expansion. The impact strength (Izot flatness) was 22 kg · cm / cm ² .

Comparative Example 4 A BMC for comparison was obtained in the same manner as in Example 7 except that the same amount of the solid isoprene rubber used in Comparative Example 3 was used in place of the liquid isoprene rubber in Example 7. At this time, the viscosity at the time of kneading was high, and it was necessary to knead for 15 minutes before the glass fiber was impregnated and then impregnated. The impact strength (Izot flatness) was 12 kg · cm / cm ² .

Comparative Example 5 Liquid isoprene rubber in Example 1 (number average molecular weight 23
000, number 24), but using liquid isoprene rubber (molecular weight: 23000, oxidation 0) instead of using SMC in the same manner, and molding under the same conditions.

Regarding the surface condition of the molded product, a faint pattern along the glass fiber, which is considered to be based on the separation of rubber, occurred on the entire surface. The swell is 9 to 12 microns, and the shrinkage is 0.01%,
The molded article obtained in Example 1 could not be obtained.

(Effect of the Invention) The low-shrinkage unsaturated polyester resin composition of the present invention is a conventionally known low-shrinkage resin composition obtained by using saturated polyester and liquid isoprene rubber or a hydride thereof in a specific unsaturated polyester resin. The molded product has a good surface smoothness compared to the molded product, is easy to be made into SMC or BMC, and has excellent mechanical strength.

Claims (1)

[Claims] 1. An unsaturated polyester (a) having a number average molecular weight of 300 or less per double bond (a) 20 to 50% by weight, a copolymerizable monomer (b) 25 to 65% by weight, a number average molecular weight 3,000 to 30,000 saturated polyester (c)
Liquid isoprene rubber containing 5 to 25% by weight and an acid group (d)
A low shrinkage unsaturated polyester resin composition containing 2 to 20% by weight (however, the total of the components (a), (b), (c) and (d) is 100% by weight).