JPH06345945A - Polyethylene terephthalate resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition excellent in melt flow and strengths and reduced in fin formation by mixing a specified polyethylene terephthalate copolymer with a specified amount of an inorganic filler, talc and a metal salt of an aliphatic monocarboxylic acid. CONSTITUTION:A bifunctional carboxylic acid (or its esterifiable derivative) component (A) based on terephthalic acid is copolymerized with a dihydroxy compound (or its esterifiable derivative) component (B) based on ethylene glycol and a polyoxyalkylene glycol derivative (C) of a molecular weight of 400-6000, represented by the formula (wherein R1 is 2-4C alkylene; R2 is H or a monocarboxylic ester group; and (n) is a positive integer) to obtain a polyethylene terephthalate copolymer having a component C content of 0.5-30wt.%. 30-95wt.% obtained copolymer is mixed with 5-60wt.% inorganic filler, 0.1-10wt.% talc of a mean particle diameter of 1-3mum and 0.05-0.5wt.% metal salt of an aliphatic monocarboxylic acid to obtain the objective composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyethylene terephthalate resin composition, and more specifically,
The present invention relates to a resin composition having excellent crystallinity, mechanical strength, fluidity, appearance, and less burr.

[0002]

2. Description of the Related Art Conventionally, polyethylene terephthalate (hereinafter abbreviated as PET) has been used for a wide range of applications such as automobiles, electric and electronic parts as engineering plastics by taking advantage of its excellent heat resistance, mechanical strength and electrical characteristics. ing.

However, compared to the same engineering plastics such as polyamide and polybutylene terephthalate, PET has a large amount of burrs generated during injection molding, and the cause of the burrs is complicated and difficult to elucidate. is there. Although there is a method of adding a large amount of glass fiber as a method for suppressing the burr of PET, there is a problem that the appearance and fluidity are deteriorated. Further, JP-A-3-86775 proposes an improvement method by adding a styrene-based copolymer having a syndiotactic structure.
Although the burr of T is slightly suppressed, the heat resistance of PET is lowered.

Further, PET has a slow crystallization rate and is 120 ° C.
Molding at the following mold temperatures is difficult, and various methods for accelerating the crystallization rate of PET have been proposed.
Examples thereof include inorganic substances, metal salts of inorganic and organic acids, ionic copolymers, plasticizers and the like. However, although they can accelerate the crystallization rate of PET, they cause deterioration of fluidity and deterioration of appearance due to bleed-out. Moreover, it has little effect on burr suppression. In addition, the characteristics required of resins are becoming more severe as electronic parts such as switches, connectors, and relays are becoming smaller and thinner, and not only mechanical and electrical characteristics but also high cycle moldability, high fluidity, In particular, it has been desired to develop a polyethylene terephthalate-based resin composition having a low flash property.

[0005]

The present inventors have arrived at the present invention as a result of repeated studies to obtain a flame-retardant resin composition having excellent crystallinity and fluidity and less burr.

That is, the present invention provides (A) a difunctional carboxylic acid having terephthalic acid as a main component or an ester-forming derivative thereof and a dihydroxy compound having ethylene glycol as a main component or an ester-forming derivative thereof and a general formula HO- ( R ₁ O) _n -R ₂ (alkylene radicals R ₁ are selected from C2-4, R ₂ is H
Alternatively, a monocarboxylic acid ester and n is a positive integer. ), Which is a copolymer obtained by copolymerizing a polyoxyalkylene glycol derivative having a molecular weight of 400 to 6000, wherein the polyoxyalkylene glycol (derivative) component occupying the copolymer is 0.5 to 3
0% by weight polyethylene terephthalate copolymer 30 to 95% by weight (in the whole composition), (B) inorganic filler 5 to 60% by weight (in the whole composition), (C) average particle size 1 to
3 μm talc 0.1 to 10% by weight (in the total composition) and (D) metal salt of aliphatic monocarboxylic acid 0.05 to
It is a polyethylene terephthalate resin composition comprising 0.5% by weight (in the entire composition).

The constituent components of the polyethylene terephthalate resin composition of the present invention will be described in detail below.

First, the "bifunctional carboxylic acid mainly containing terephthalic acid or its ester-forming derivative" constituting the component (A) used in the present invention means terephthalic acid or its lower alkyl ester or phenyl ester. Such an ester-forming derivative may contain a dicarboxylic acid component other than the terephthalic acid component. This acid other than terephthalic acid is used in an amount within a range that does not significantly lower the melting point of the polymer when the terephthalic acid component is used alone. Other dicarboxylic acid components include phthalic acids such as isophthalic acid, phthalic acid, methylterephthalic acid and methylisophthalic acid, naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid and 1,5-naphthalenedicarboxylic acid, 4 , 4'-diphenyldicarboxylic acids such as diphenyldicarboxylic acids, 4,
Aromatic dicarboxylic acids such as dipheninoxyethanedicarboxylic acids such as 4'-diphenoxyethanedicarboxylic acid or lower alkyl esters, phenyl esters thereof,
Examples thereof include aliphatic or alicyclic dicarboxylic acids such as succinic acid, adipic acid, sepacic acid, azelaic acid, decanedicarboxylic acid, and cyclohexanedicarboxylic acid, or lower alkyl esters and phenyl esters thereof.

In the present invention, "a glycol mainly comprising ethylene glycol or an ester-forming derivative thereof" is an ester-forming derivative of ethylene glycol such as ethylene glycol or ethylene oxide, and other than the ethylene glycol component. The glycol component can be used in combination with an amount within a range that does not significantly lower the melting point of the polymer when the ethylene glycol component is used alone. Other glycol components include trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, 1,
Aliphatic or alicyclic glycols such as 4-cyclohexanedimethanol or its ester-forming derivatives, dihydroxybenzenes such as hydroquinone and resorcin, 2,2-bis (4'-hydroxyphenyl) propane, 2,2-bis Examples include aromatic glycols such as bisphenols such as (3 ′, 5′-dibromo-4′-hydroxyphenyl) propane and 2,2-bis (4′-hydroxyphenyl) sulfone, and ester-forming derivatives thereof. .

In the present invention, a base polyester comprising the above-mentioned "bifunctional carboxylic acid mainly containing terephthalic acid or its ester-forming derivative" and "glycol mainly ethylene glycol or its ester-forming derivative" is used. the following general formula _{HO- (R 1 O) n -R} 2 (R 1
The alkylene group selected from C2-4, R ₂ is H or a monocarboxylic acid ester, n is a positive integer. ) Is copolymerized with a polyoxyalkylene glycol derivative. The molecular weight is in the range of 400 to 6000. When the molecular weight is less than 400, the effect of copolymerization does not appear, and when the molecular weight exceeds 6000, the reactivity is significantly reduced.
A preferable copolymer cannot be obtained. Preferred specific examples of the compound applicable to the present invention include polyoxyethylene glycol, polyoxypropylene glycol, and monocarboxylic acid ester derivatives thereof.
Of these, polyoxyethylene glycol is particularly desirable.

The above compounds may be used alone or in combination of two or more.

The content (ratio of the polyalkylene glycol derivative) in the copolymer is 0.5 to 30% by weight. When the amount is less than 0.5% by weight, the effect of improving the burr resistance is not exhibited, and when the amount is more than 30% by weight, the copolymerized polymer is compared with the melting point of the homopolymer not copolymerized with the polyalkylene glycol. The melting point of the product is largely decreased, and the heat resistance of the molded product is decreased.

The polyester copolymer can be prepared by a known method, for example, a method in which the "terephthalic acid component" and the "ethylene gucuroil component" are esterified or transesterified and then melt polycondensed before the transesterification or esterification reaction is started. The polyalkylene glycol derivative may be added during the reaction or after the reaction is completed and during the polycondensation reaction, and the polycondensation reaction may be completed after the addition. It is also possible to solid-phase polymerize this copolymer to increase the molecular weight.

As the inorganic filler (B) used in the present invention, fibrous fillers such as glass fiber, graphite fiber, aramid fiber, silica fiber and alumina fiber, and
Powdery or granular fillers such as carbon black, silica, glass beads, calcium silicate, whiskers, kaolin and wollastonite, and plate-like fillers such as mica and glass flakes can be used. These inorganic fillers can be used alone or in combination of two or more. When using these inorganic fillers, it is desirable to use a sizing agent or a surface treating agent together, if necessary. If this example is shown, an epoxy compound, an isocyanate compound,
It is a functional compound such as a silane compound and a titanate compound. These compounds can be prepared by subjecting an inorganic filler to a surface treatment or a converging treatment in advance, or can be prepared by a method of adding the same at the time of material preparation.

In the present invention, the compounding amount of the inorganic filler (B) is 5 to 60% by weight. If the content of the inorganic filler is less than 5% by weight, the mechanical strength of the obtained molded product will be problematic. Further, if the content of the inorganic filler exceeds 60% by weight, the molding process becomes difficult. The amount of the functional surface treatment agent used together is 0.05 to 10% by weight, preferably 1 to 5% by weight, based on the inorganic filler.

Next, the average particle size of the talc of the component (C) used in the present invention is 1 to 3 μm. Average particle size is 1 μm
If it is less than 3, the mechanical strength of the obtained molded article decreases,
If it exceeds μm, the effect of reducing burrs is reduced. The blending amount of talc is in the range of 0.1 to 10% by weight. If the content is less than 0.1% by weight, crystallization of the obtained molded product is slow, and if it exceeds 10% by weight, mechanical strength is lowered, which is not preferable.

Further, the metal salt of the aliphatic monocarboxylic acid as the component (D) used in the present invention is known as a crystal nucleating agent, but in the present invention, it is incorporated so as to function as a deburring agent. Specific examples thereof include sodium palmitate, calcium stearate, zinc behenate, sodium montanate, and the like, among which sodium palmitate is preferable. Ionic copolymers composed of α-olefins and α, β-unsaturated carboxylates are known as crystal nucleating agents, but their use in the present invention is preferred because they increase melt viscosity and hinder fluidity. Absent. The compounding amount of the metal salt of the aliphatic monocarboxylic acid is in the range of 0.05 to 0.5% by weight. If the content is less than 0.05% by weight, burrs are often generated during molding, and if it exceeds 0.5% by weight, the thermal stability of the obtained resin composition is impaired.

The polyethylene terephthalate resin composition of the present invention further comprises known additives such as lubricants, nucleating agents, flame retardants and flame retardants other than the above-mentioned components in order to impart desired properties depending on the purpose. Of course, it is also possible to blend an auxiliary agent, a release agent, an antistatic agent, a surfactant, a plasticizer, a coloring agent, a heat resistance stabilizer, an ultraviolet absorber and the like.

The polyethylene terephthalate resin composition of the present invention can be easily prepared by known equipment and methods generally used as conventional resin composition preparation methods. For example, 1) a method in which the respective components are mixed, then kneaded and extruded by an extruder to prepare pellets, and then molded, 2)
A method of once preparing pellets having different compositions, mixing the pellets in a predetermined amount and returning to molding, and obtaining a molded article of the target composition after molding, 3) directly charging one or more of each component into a molding machine, etc. Either can be used. In addition, mixing a part of the resin component in the form of fine powder with the other components and adding the powder is a preferable method for uniformly blending these components.

[0020]

EXAMPLES The present invention will be described in more detail below with reference to examples. Moreover, the measuring method of the characteristic evaluation shown in the examples is as follows.

1) Method of measuring physical properties Tensile test According to ASTM D638. Izod impact strength According to ASTM D 256.

2) Method of measuring fluidity A test die for measuring rod flow length (cavity: width 10 mm ×
Molding is performed under the following conditions using a thickness of 0.7 mm), and the fluidity is evaluated from the flow length (molded product length). Molding conditions: Cylinder temperature: 280 ° C Injection pressure: 100 kg / cm ² Mold temperature: 80 ° C

3) Burr Evaluation A molded product having a bar flow length of 0.05 mm is regarded as a burr and compared with a bar flow length of 0.5 mm to obtain a burr index. Molding conditions are cylinder temperature 280 ℃, mold temperature 8
0 ° C, injection pressure 400 kg / cm ² , injection speed 100 m
m / sec. The lower the index, the less burr.

[0024]

[Equation 1]

4) Visual inspection of molded product A disk (100 mm diameter, 3 mm thickness) is molded and observed with reference to the presence or absence of differently colored spots and the degree thereof, and judgment is made according to the following ranks. Spots ○: None △: A little ×: Many

5) Crystallization temperature measurement method The crystallization temperature was measured by a differential calorimeter using a sample obtained by performing melting and quenching operations in advance, in a nitrogen stream,
The temperature is raised at 10 ° C./min, and the crystallization temperature at the time of temperature rise is measured. The smaller the value of the crystallization temperature, the easier the crystallization.

[0027]

Examples 1 to 6 and Comparative Examples 1 to 10 The components shown in Tables 1 and 2 were added in the amounts shown in Tables 1 and 2 and mixed, and then pelletized compositions were prepared using an extruder. . Next, various test pieces were prepared by using the pellets or by injection molding from the pellets, and the above evaluation was performed. The results are shown in Tables 1-2.

[0028]

[Table 1]

[0029]

[Table 2]

As is clear from the above examples, the resin composition of the present invention effectively improves the following characteristics. 1) Excellent mechanical properties such as tensile properties and Izod impact strength. 2) High fluidity. 3) Less burr is generated. 4) No occurrence of differently colored spots on the molded product. 5) Easy crystallinity.

Claims (1)

[Claims] 1. A difunctional carboxylic acid having (A) terephthalic acid as a main component or an ester-forming derivative thereof and a dihydroxy compound having ethylene glycol as a main component or an ester-forming derivative thereof, and a compound represented by the general formula HO- (R ₁ O ) _n -R ₂ (alkylene radicals R ₁ are selected from C2-4, R ₂ is H
Alternatively, monocarboxylic acid ester, n is a positive integer. ) Is a copolymer obtained by copolymerizing a polyoxyalkylene glycol derivative having a molecular weight of 400 to 6000, wherein 0.5 to 30% by weight of the polyoxyalkylene glycol derivative component in the copolymer is present. 30-95% by weight (in the total composition), (B) inorganic filler 5-60% by weight (in the entire composition), (C) talc having an average particle diameter of 1 to 3 μm A polyethylene terephthalate resin composition comprising 1 to 10% by weight (in the whole composition) and (D) a metal salt of an aliphatic monocarboxylic acid 0.05 to 0.5% by weight (in the whole composition).