JP2647674B2 - Thermoplastic resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermoplastic resin composition, and more particularly to a thermoplastic resin composition having relatively low rigidity and excellent impact resistance and heat resistance.

Technical background of the invention and its problems In general, thermoplastic polyester resins are excellent in heat resistance, abrasion resistance, mechanical strength and electrical properties, and have favorable properties as engineering plastics, but they have high impact resistance. There is a drawback that the property is poor. Hitherto, in order to improve this drawback, various methods have been proposed in which another type of modifying resin is blended with a thermoplastic polyester resin. For example, a method of blending an ethylene-ethyl acrylate copolymer, an ethylene-vinyl acetate copolymer, or both with polybutylene terephthalate (JP-A-58-4)
No. 5,255), a method of blending a thermoplastic polyester resin with an ethylene-glycidyl methacrylate copolymer, glass beads and glass fiber (JP-A-57-192,
No. 455) has been proposed.

However, the impact resistance of the thermoplastic polyester resin obtained by the above method was not always sufficient.

On the other hand, polyethylene polymers such as polyethylene, ethylene-vinyl acetate copolymer and ethylene-acrylate copolymer are excellent in flexibility and impact resistance, so that lids of closed containers, slippers, artificial grass, Ski boots, cooling boxes, tubes, detergent caps, soles,
Widely used for various sealing materials. Also,
Ethylene-based ionomers are widely used for applications such as golf ball skins, ski boots, and automobile parts because of their excellent toughness, wear resistance, and cold impact resistance.

However, these ethylene copolymers are inferior in heat resistance, and when the molded articles are exposed to high-temperature conditions, they are thermally deformed, so that they cannot be used for applications requiring heat resistance.

Therefore, conventionally, when it is necessary to use such an ethylene copolymer molded article at a relatively high temperature, it is necessary to provide the ethylene copolymer constituting the molded article with a crosslinked structure. Thus, a method of imparting heat resistance to a molded article has been adopted.

The method of the cross-linking is roughly classified into a method of irradiating radiation or ultraviolet rays having high energy, and a chemical method using an organic peroxide. However, the former method has a problem that the source cost is very high, and both methods have a problem that the degree of crosslinking of the ethylene copolymer is low and the effect of improving heat resistance is not yet sufficient. Was. Moreover, the once-crosslinked ethylene copolymer is
Since the molecular network structure is fixed and loses thermal degeneracy, there is also a problem that it cannot be processed by a normal processing method for an ethylene polymer.

By the way, as described in JP-A-61-163956, the present inventors impair the heat resistance of a thermoplastic polyester resin by blending a modified graft with a thermoplastic polyester resin at a specific ratio. It has been found earlier that the impact resistance can be greatly improved without any problem. However, as a result of further study, the present inventors have found that, although the polyester resin composition for molding described in JP-A-61-163,956 has relatively low rigidity,
It has been found that the tensile impact strength, which is a measure of impact resistance evaluation, is not always sufficient depending on the application.

Thus, the present inventors have conducted intensive studies to obtain a thermoplastic resin composition having relatively low rigidity and excellent impact resistance and heat resistance, and found that (A) an aromatic resin containing terephthalic acid as a main component. (B) a thermoplastic polyester resin comprising a carboxylic acid component and a diol component having an aliphatic diol or an alicyclic diol component having 2 to 8 carbon atoms as a main component;
A copolymer containing at least one monomer unit selected from the group consisting of α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester and ethylene unit in a specific ratio is added with an unsaturated carboxylic acid. It has been found that an acid-modified copolymer obtained by graft-polymerizing an anhydride at 0.01 to 8% by weight may be blended at a specific ratio, and the present invention has been completed.

Object of the Invention The present invention aims to solve the problems associated with the prior art as described above, and has a relatively low rigidity, and a thermoplastic resin composition having excellent impact resistance and heat resistance. It is intended to provide.

SUMMARY OF THE INVENTION The thermoplastic resin composition according to the present invention comprises (A) an aromatic carboxylic acid component containing terephthalic acid as a main component and an aliphatic diol or alicyclic diol component having 2 to 8 carbon atoms as a main component. 35-59% by weight of a thermoplastic polyester resin comprising a diol component and (B) 78-98 mol% of ethylene units, and α, β
A copolymer containing from 22 to 2 mol% of at least one monomer unit selected from the group consisting of unsaturated carboxylic acids and α, β-unsaturated carboxylic acid esters; And 65 to 41% by weight of an acid-modified copolymer obtained by graft polymerization and having a flexural rigidity of 1,000 MPa or less.

Specific description of the invention Hereinafter, the thermoplastic resin composition according to the present invention will be specifically described.

The thermoplastic polyester resin (A) used in the present invention comprises a carboxylic acid component and an alcohol component. In the present invention, an aromatic carboxylic acid component containing terephthalic acid as a main component and a fatty acid having 2 to 8 carbon atoms are used. Use is made of a thermoplastic polyester resin comprising a diol component having an aliphatic diol component or an alicyclic diol component as a main component.

As the aromatic dicarboxylic acid component, in addition to terephthalic acid, isophthalic acid, 1,4-naphthalene dicarboxylic acid, 2,6
-Naphthalene dicarboxylic acid or the like may be used as a minor component.

Further, as the diol component, specifically, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like are preferably used, In the present invention, diethylene glycol, triethylene glycol or the like can be used as a small component.

As the thermoplastic polyester resin (A) used in the present invention, specifically, polyethylene terephthalate,
Examples thereof include polypropylene terephthalate and polybutylene terephthalate. Among them, polyethylene terephthalate and polybutylene terephthalate are particularly preferably used. In the present invention, the above-mentioned thermoplastic polyester resins may be used alone or in combination of two or more.

In the present invention, (A) the thermoplastic polyester resin comprises:
It is used in an amount of 35 to 59% by weight, preferably 40 to 55% by weight, based on 100% by weight of the total weight of (A) the thermoplastic polyester resin and (B) the acid-modified copolymer. (A) When the blending amount of the thermoplastic polyester resin exceeds 59% by weight, the rigidity is increased and the tensile impact strength is undesirably reduced. On the other hand, the blending amount of (A) the thermoplastic polyester resin is
If it is less than 35% by weight, heat resistance is remarkably reduced, which is not preferable.

The (B) acid-modified copolymer used in the present invention comprises an ethylene unit and at least one monomer unit selected from the group consisting of α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester. Is a copolymer obtained by graft-polymerizing an anhydride of an unsaturated carboxylic acid to a copolymer consisting of

In the present invention, the term “α, β-unsaturated carboxylic acid” is used in a sense that also includes an anhydride of α, β-unsaturated carboxylic acid. Specific examples of the α, β-unsaturated carboxylic acid used as a monomer unit in the present invention include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylic acid anhydride, methacrylic anhydride, and maleic anhydride. And itaconic anhydride.

In the present invention, α, used as a monomer unit,
As the β-unsaturated carboxylic acid ester, specifically,
Acrylic esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, or methyl methacrylate, ethyl methacrylate, methacrylic acid n-butyl,
Methacrylates such as isobutyl methacrylate are preferably used.

The anhydride of the unsaturated carboxylic acid is not grafted,
That is, a copolymer that has not been acid-modified (hereinafter, may be referred to as an “unmodified copolymer”) has 78 units of ethylene units.
In the present invention, the content of the ethylene α, β-unsaturated carboxylic acid and the α, β-constituent constituting the unmodified copolymer is from 98 to 98 mol% and from 22 to 2 mol% of the monomer unit.
The composition ratio of the unsaturated carboxylic acid ester can be freely changed according to the required rigidity, heat resistance and impact resistance of the resin composition. A preferable unmodified copolymer is represented by the following formula (1). In addition, the copolymer satisfies at least one of the following formulas (2) and (3) at the same time.

78 ≦ a ≦ 98 (1) 0 ≦ b ≦ 12 (2) 0 ≦ c ≦ 22 (3) where a is the molar concentration (mol%) of ethylene in the unmodified copolymer, and b Is the molar concentration (mol%) of the α, β-unsaturated carboxylic acid in the unmodified copolymer, and c is the molar concentration (mol%) of the α, β-unsaturated carboxylic acid ester in the unmodified copolymer. It is.

As the unmodified copolymer, specifically, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylic acid-isobutyl acrylate copolymer, ethylene-acrylic acid-acrylic acid n -Butyl copolymer, ethylene-methacrylic acid-isobutyl acrylate copolymer, ethylene-n-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-
Ethyl acrylate copolymer, ethylene-isobutyl acrylate copolymer, ethylene-n-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-isobutyl methacrylate Copolymer, ethylene-methacrylic acid n-
Butyl copolymer and the like.

Melt flow rate of the above unmodified copolymer (JIS-K
−6760, temperature 190 ° C, load 2,160g, same hereafter)
In the present invention, an unmodified copolymer having a melt flow rate in the range of 0.5 to 200 dg / min is preferable.

Specific examples of the anhydride of the unsaturated carboxylic acid graft-polymerized to the unmodified copolymer include maleic anhydride, itaconic anhydride, and bicyclo (2,2,1) -5-heptene-2,3. -An anhydride of a dibasic acid such as an anhydride of a dicarboxylic acid is used, and among them, maleic anhydride is particularly preferably used.

The amount of the unsaturated carboxylic acid anhydride grafted to the unmodified copolymer is slightly different depending on the type of the unmodified copolymer and the anhydride, but the impact resistance and the color tone of the resin composition are changed. Considering this, the graft amount is 0.01 to 8% by weight, preferably 0.1 to 4% by weight, based on the unmodified copolymer.

In the present invention, an unsaturated carboxylic acid anhydride can be graft-polymerized to the unmodified copolymer by a conventionally known method. For example, graft polymerization can be carried out using a radical initiator such as a peroxide in a suitable solvent or by a melting method using an extruder or the like.

As the radical initiator used in the graft polymerization reaction, compounds that decompose to generate radicals such as peroxyesters, diacyl peroxides, dialkyl peroxides, peroxydicarbonates, and hydroperoxides are used. , Specifically, t
-Butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxy-2-ethylhexanate, t-butylperoxypivalate, t-butylhydroperoxide, 1,1-bis (t- Butylperoxy) 3,3,5-trimethylcyclohexane, 2,5-
Dimethyl-2,5-bis (t-butylperoxy) hexane-3 and the like are used. Among them, t-butyl hydroperoxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane-3 and the like are preferably used. The amount of the radical initiator varies depending on the amount of the anhydride of the unsaturated carboxylic acid used, but is usually 0.01 to 3 parts by weight based on 100 parts by weight of the unmodified copolymer.

In the present invention, among the (B) acid-modified copolymer obtained by the above method, the melt flow rate is 0.01 to 200 dg /
Min is preferred, and the melt flow rate is particularly preferably in the range of 0.1 to 50 dg / min. Melt flow rate is within the above range (B)
In order to obtain the acid-modified copolymer, the reaction conditions in the graft polymerization, for example, the type of the radical initiator, the graft polymerization reaction temperature, the pressure time and the like may be appropriately selected. In the present invention, the graft polymerization reaction temperature is usually in the range of 120 to 300 ° C.

In the present invention, (B) the acid-modified copolymer is the total weight of (A) the thermoplastic polyester resin and (B) the acid-modified copolymer.
It is used in an amount of 65 to 41% by weight, preferably 60 to 45% by weight, based on 100% by weight.

The thermoplastic resin composition according to the present invention is produced by melting (A) the thermoplastic polyester resin and (B) the acid-modified copolymer simultaneously or in an arbitrary order and mixing them. This melt mixing is usually performed in a single screw extruder,
This is performed using a screw extruder, a kneader, or the like. The temperature at the time of melt-kneading is preferably about 235 to 300 ° C.

The thermoplastic resin composition according to the present invention, ethylene-ethyl acrylate copolymer, ethylene-isobutyl acrylate copolymer, ethylene-n-butyl acrylate copolymer, ethylene such as ethylene-methacrylic acid copolymer −
α, β-unsaturated carboxylic acid ester copolymer, or ethylene-methacrylic acid copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid-isobutyl acrylate copolymer, ethylene-methacrylic acid-acrylic acid n -Binary and ternary ethylene such as butyl copolymer-
An α, β-unsaturated carboxylic acid-based copolymer or another olefin-based resin can be blended as a modifier for appearance and fluidity.

Further, the thermoplastic resin composition according to the present invention may be blended with polycarbonate, polyester elastomer, polyamide elastomer, and the like.

Further, an inorganic filler can be arbitrarily added to the thermoplastic resin composition according to the present invention according to required physical properties. Specific examples of the inorganic filler include glass fiber, carbon fiber, aluminum fiber, brass fiber, aluminum powder, zinc powder, silica, alumina, silica-alumina, zinc white, calcium carbonate, barium carbonate, aluminum sulfate, and sulfuric acid. Barium, calcium sulfate, kaolin,
Talc, mica, bentonite, diatomaceous earth, silica sand, quartz powder,
Examples include carbon black and glass powder. Above all, the addition of glass fiber can further improve the heat resistance, dimensional stability, abrasion, and the like of the thermoplastic resin composition according to the present invention. The amount of glass fiber added
The amount is 5 to 100 parts by weight, preferably 10 to 60 parts by weight, based on 100 parts by weight of the total of (A) the thermoplastic polyester resin and (B) the acid-modified copolymer.

In addition, the thermoplastic resin composition according to the present invention, additives such as antioxidants, weather stabilizers, lubricants, antistatic agents, organic or inorganic pigments, flame retardants, flame retardant aids, etc. Can be added in a range that does not impair.

The thermoplastic resin composition according to the present invention can be made into various molded products by various molding methods such as extrusion molding, injection molding, and blow molding.

Effects of the Invention The thermoplastic resin composition according to the present invention comprises (A) 35 to 59% by weight of a thermoplastic polyester resin and (B) an α, β-unsaturated carboxylic acid and an α, β-unsaturated carboxylic acid ester. A copolymer containing at least one monomer unit and ethylene unit selected from the group consisting of a specific ratio,
An acid-modified copolymer obtained by graft-polymerizing an anhydride of an unsaturated carboxylic acid in an amount of 0.01 to 8% by weight is blended with 65 to 41% by weight of a flexural rigidity (ASTM D-747) of 1,000 MPa or less. It has relatively low rigidity and excellent impact resistance and heat resistance. Among them, (A) 40 to 55% by weight of a thermoplastic polyester resin and (B) 60 to 45% by weight of an acid-modified copolymer
Is preferable.

Therefore, the thermoplastic resin composition according to the present invention is widely used for electrical parts such as connectors, computer parts, tuners, and air conditioners, or for automotive parts such as car heater fans, instrument panels, bumpers, and wheel covers. Can be used.

Hereinafter, the present invention will be described with reference to examples, the present invention,
It is not limited to these examples.

First, methods for measuring physical properties in Examples and Comparative Examples are described below.

(I) Mel flow rate (MFR) Measured at a temperature of 190 ° C. and a load of 2,160 g according to JIS K-6760.

(Ii) Flexural rigidity A test piece prepared from an injection-molded square plate having a thickness of 2 mm is measured in accordance with ASTM D-747.

(Iii) Tensile impact strength A test piece made from a 2 mm-thick injection-molded square plate, in accordance with ASTM D-1822, at a measurement temperature of 23 ° C., in the direction in which the resin flows during injection molding (longitudinal direction). , And a direction (lateral direction) perpendicular to the direction.

(Iv) Heat resistance An injection square plate with a thickness of 2 mm, length of 150 mm and width of 80 mm is used as a test piece.
The test piece is heated at 90 ° C. for one hour, and the difference in the heat shrinkage (heat word shrinkage−molding shrinkage) is measured in the vertical and horizontal directions.

Example 1 2 parts by weight of maleic anhydride was added to 100 parts by weight of an ethylene-ethyl acrylate copolymer (ethyl acrylate content: 8.5 mol%, MFR: 5 dg / min) at 260 ° C. using a single screw extruder.
At a temperature of 0.25 parts by weight of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane-3, graft polymerization was carried out to obtain an acid-modified copolymer (hereinafter referred to as MFR 0.8 dg / min). "Acid-modified copolymer [I]" was obtained.

41 parts by weight of the acid-modified copolymer [I] thus obtained was mixed with polybutylene terephthalate (Toray P-1401-).
X06) and 59 parts by weight were melt-kneaded at 260 ° C. using a twin-screw extruder to obtain a resin composition.

For the obtained resin composition, test specimens for measuring physical properties were prepared at a molding temperature of 260 ° C. and a mold temperature of 20 ° C., and the flexural rigidity, tensile impact strength and heat resistance were evaluated according to the above-mentioned methods.

 Table 1 shows the results.

Example 2 In Example 1, except that the compounding ratio of the acid-modified copolymer [I] and polybutylene terephthalate was changed to 50 parts by weight of the acid-modified copolymer [I] and 50 parts by weight of polybutylene terephthalate. A resin composition was obtained in the same manner as in Example 1, and the physical properties were evaluated.

 Table 1 shows the results.

Comparative Example 1 In Example 1, except that the mixing ratio of the acid-modified copolymer [I] and polybutylene terephthalate was 20 parts by weight of the acid-modified copolymer [I] and 80 parts by weight of polybutylene terephthalate. A resin composition was obtained in the same manner as in Example 1, and the physical properties were evaluated.

 Table 1 shows the results.

Comparative Example 2 In Example 1, except that the mixing ratio of the acid-modified copolymer [I] and polybutylene terephthalate was 80 parts by weight of the acid-modified copolymer [I] and 20 parts by weight of polybutylene terephthalate. A resin composition was obtained in the same manner as in Example 1, and the physical properties were evaluated.

 Table 1 shows the results.

Example 3 An MFR was prepared in the same manner as in Example 1 except that the amount of maleic anhydride was changed to 0.3 part by weight.
An acid-modified copolymer at 0.9 dg / min (hereinafter referred to as “acid-modified copolymer [II]”) was obtained.

A resin composition was prepared from 50 parts by weight of the obtained acid-modified copolymer [II] and 50 parts by weight of polybutylene terephthalate in the same manner as in Example 1, and the physical properties were evaluated.

 Table 1 shows the results.

Example 4 In Example 1, instead of the ethylene-ethyl acrylate copolymer having an ethyl acrylate content of 8.5 mol% and MFR of 5 dg / min, an ethyl acrylate content of 15.7 mol% and MF
MFR 0.5 dg in the same manner as in Example 1 except that an ethylene-ethyl acrylate copolymer of R 7.1 dg / min was used.
/ Min of an acid-modified copolymer (hereinafter referred to as “acid-modified copolymer [III])”.

A resin composition was obtained in the same manner as in Example 1 using 50 parts by weight of the obtained acid-modified copolymer [III] and 50 parts by weight of polybutylene terephthalate, and the physical properties were evaluated.

 Table 1 shows the results.

Example 5 In Example 1, instead of the ethylene-ethyl acrylate copolymer, an ethylene-methacrylic acid-isobutyl acrylate copolymer (a methacrylic acid content of 3.8 mol%,
Isobutyl acrylate content 2.6 mol%, MFR 10dg /
MFR) in the same manner as in Example 1 except that
An acid-modified copolymer (hereinafter, referred to as “acid-modified copolymer [IV]) at 1.2 dg / min was obtained.

A resin composition was obtained from 50 parts by weight of the obtained acid-modified copolymer [IV] and 50 parts by weight of polybutylene terephthalate in the same manner as in Example 1, and the physical properties were evaluated.

 Table 1 shows the results.

Comparative Example 3 In Example 1, an unmodified ethylene-ethyl acrylate copolymer (ethyl acrylate content 8.5 mol%, MFR 5 dg / min) was used in place of the acid-modified copolymer [I]. 50 parts by weight of copolymer and polybutylene terephthalate
50 parts by weight to obtain a resin composition in the same manner as in Example 1,
The physical properties were evaluated.

 Table 1 shows the results.

Comparative Example 4 In the same manner as in Example 1, an ethylene-ethyl acrylate copolymer (ethyl acrylate content 8.5 mol%, MFR 5d
g / min).

 Table 1 shows the results.

Claims (1)

(57) [Claims] 1. A thermoplastic polyester comprising: (A) an aromatic carboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of an aliphatic diol or alicyclic diol component having 2 to 8 carbon atoms. 35 to 59% by weight of a resin; (B) 78 to 98 mol% of ethylene units;
A copolymer containing from 22 to 2 mol% of at least one monomer unit selected from the group consisting of unsaturated carboxylic acids and α, β-unsaturated carboxylic acid esters; A thermoplastic resin composition comprising 65% to 41% by weight of an acid-modified copolymer obtained by graft polymerization and having a flexural rigidity of 1,000 MPa or less.