JPH07133413A - Polyethylene terephthalate resin composition - Google Patents

Abstract

PURPOSE:To obtain a composition consisting of a polyethylene terephthalate, an inorganic filler, an aromatic compound alkali metal salt and a polyalkylene glycol and capable of reducing gas generation in molding while keeping good mechanical characteristics. CONSTITUTION:This resin composition is obtained by blending (A) 20-80wt.% of polyethylene terephthalate with (B) 0.1-60wt.% of an inorganic filler, (C) 0.05-20wt.% of an alkali metal salt of an aromatic compound having one or more phenolic hydroxyl groups and carboxyl group and (D) 0.5-10wt.% of a polyalkylene glycol expressed by formula I (R1 and R2 are each H, a 10-30C alkyl or aryl; X is a 2-6C alkylene) and having at least one end blocked and having 5000-20000 average molecular weight. As the component B, preferably, talc is used in an amount of 0.1-20wt.%. As the component D, polyethylene glycol is preferably used. As the component C, a salt of an aromatic compound selected from phenols having a carboxyl group, e.g. parahydroxybenzoic acid and a metal, e.g. lithium or sodium is preferably used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition obtained by blending polyethylene terephthalate with an inorganic filler, an alkali metal salt of an aromatic compound and polyalkylene glycol. More specifically, the present invention relates to a polyethylene terephthalate resin composition in which the gas generated during molding is reduced without impairing the mechanical properties of the resin.

[0002]

2. Description of the Related Art Polyethylene terephthalate has been conventionally used as an injection molding material, but a satisfactorily molded product cannot be obtained because of its extremely low crystallization rate. Therefore, as a method of improving moldability, in Japanese Patent Publication No. 45-18768, etc., a mold temperature of 120 to 170 is obtained by adding glass fiber to polyethylene terephthalate.
It can be molded at ℃. However, at a mold temperature of 110 ° C. or lower, which is generally used in ordinary injection molding, crystallization is insufficient and only a non-uniform molded product can be obtained.

[0003]

Therefore, various crystallization nucleating agents and crystallization accelerators have been investigated as further improvements. For example, in JP-A-61-268752 and JP-A-58-187447, an organic ester compound, and in JP-B-2-48584, there are 3 carbon atoms.
0 or less ester, ketone, sulfone, sulfoxide,
Low molecular weight organic compounds of nitriles or amides are disclosed, and the addition of these compounds can accelerate the crystallization of the polyethylene terephthalate resin composition.

However, when these additives are used, the molding stability is lowered, that is, the resin in the molding machine cylinder is deteriorated by the decomposition gas at the time of molding. In addition, the deterioration phenomenon of the resin causes problems such as mold stains and a defective appearance of a molded product.

[0005]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have solved the above problems by blending an alkali metal salt of a specific aromatic compound and polyethylene glycol having a specific structure. They have found what they can do and have reached the present invention. That is, the gist of the present invention is (A) polyethylene terephthalate: 20 to 80% by weight, (B) inorganic filler: 0.1 to 60% by weight, (C).
Alkali metal salt of aromatic compound having one or more phenolic hydroxyl group and one or more carboxyl group in one molecule: 0.0
5 to 20% by weight, and (D) an average molecular weight of 5,000 to 2 represented by the following formula (I) with at least one end blocked.
10,000 polyalkylene glycol: 0.5-10
A polyethylene terephthalate resin composition comprising:

[0006]

[Chemical 2] (R ₁ and R _{2 are} hydrogen or an alkyl group or aryl group having 1 to 30 carbon atoms. X: a linear or branched alkylene group having 2 to 6 carbon atoms, provided that R ₁ and R ₂ are hydrogen at the same time. There is no.)

The present invention will be described in detail below. The polyethylene terephthalate (A) used in the present invention (hereinafter sometimes simply abbreviated as “PET”) is, for example, a dicarboxylic acid having at least 90 mol% terephthalic acid or an ester-forming derivative component thereof, and at least 90 mol. Esterification reaction or transesterification reaction with a glycol component whose% is ethylene glycol,
It is a polymer obtained by subsequent polycondensation reaction.

Preferred examples of the ester-forming derivative of dicarboxylic acid include a dialkyl ester of terephthalic acid. Examples of the dicarboxylic acid that can be used in combination with terephthalic acid in the range of 10 mol% or less as the dicarboxylic acid component include phthalic acid, isophthalic acid, adipic acid, sebacic acid, naphthalene-1,4- or 2,6-dicarboxylic acid. To be Also, 1 as a glycol component
Examples of glycol that can be used in combination with ethylene glycol in the range of 0 mol% or less include propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, and other glycols. .

The degree of polymerization of polyethylene terephthalate used in the present invention is not particularly limited, but it is preferable to use an intrinsic viscosity (phenol / 1,1,2,2-tetrachloroethane = 1/1 (weight ratio) mixed solution). 25
(Measured at ° C) in the range of 0.4 to 1 dl / g is used. In the present invention, as the inorganic filler (B), glass fiber, carbon fiber, mineral fiber, silicon carbide fiber,
Fibrous fillers such as potassium titanate fiber and gypsum fiber,
Powdery and granular fillers such as mica, talc, wollastonite, silica, kaolin and glass beads, 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.

If necessary, a sizing agent or a surface treatment agent may be used in combination. For example, it is a functional compound such as an epoxy compound, an isocyanate compound, and a silane compound. These compounds may be used by subjecting the inorganic filler to a surface treatment or a converging treatment in advance, or may be added at the same time when kneading the materials. In the present invention, the compounding amount of the inorganic filler (B) is 0.1 to 60% by weight, preferably 5 to 50% by weight. When the content of the inorganic filler exceeds 60% by weight, the molding process becomes difficult and the mechanical strength of the molded product also becomes problematic. The amount of the functional surface-treating agent used in combination is 0.1 to 10% by weight, preferably 0.5 to 2 with respect to the inorganic filler.
% By weight.

The alkali metal salt (C) of an aromatic compound used in the present invention is an alkali metal salt of an aromatic compound having at least one phenolic hydroxyl group and at least one carboxyl group in one molecule, and is usually acetone. Insoluble ones are selected. Preferred examples include those represented by the following formula (II). Specifically, para-hydroxybenzoic acid, 4-hydroxy-isophthalic acid, 5-hydroxy-
One or more aromatic compounds selected from phenols having a carboxyl group such as isophthalic acid, lithium,
Examples thereof include metal salts with alkali metals such as sodium and potassium.

[0012]

[Chemical 3] (In the formula (II), M is an alkali metal. M, n = 1 or 2.) The compounding amount of this ionic compound is 0.05 to 20% by weight based on the whole composition. If it is less than 0.05% by weight, the effect as a crystal nucleating agent cannot be obtained, and if it exceeds 20% by weight, the decomposition of polyethylene terephthalate is promoted to lower the mechanical strength of the molded article.

The polyalkylene glycol (D) having one end blocked, which is used in the present invention, has a structure represented by the following formula (I). Since the polyalkylene glycol having such a specific structure has a higher mobility of the molecular chain than polyethylene terephthalate, it is presumed that the mobility of the molecular chain of polyethylene terephthalate is improved by the plasticizing effect and the crystallization promoting effect is also exhibited. .

[0014]

[Chemical 4] (R ₁ and R _{2 are} hydrogen or an alkyl group or an aryl group having 1 to 30 carbon atoms. However, both are not hydrogen at the same time. X: a linear or branched alkylene group having 2 to 6 carbon atoms.) The average molecular weight of the polyalkylene glycol (D) in the present invention is in the range of 5,000 to 20,000, preferably 10,000 to 20,000. If the average molecular weight is less than 5,000, it may cause generation of volatile gas at the time of molding and stains of the mold. On the other hand, when the average molecular weight exceeds 20,000, a sufficient plasticizing effect cannot be obtained and a problem occurs in dimensional stability, which is not preferable.

Blending amount of polyalkylene glycol (D)
Is from 0.5 to 10% by weight, preferably 1
~ 5% by weight. Crystals when the compounding amount is less than 0.5% by weight
The effect of promoting oxidization is small, and when the content exceeds 10% by weight,
The mechanical strength of the shaped product is significantly reduced. In addition, the formula (I)
Medium, R₁And R₂Is hydrogen or an alkyl having 1 to 30 carbon atoms
Represents an aryl group or an aryl group, but both ends are
It cannot be the basis. R₁And R ₂When both are hydrogen
Is not preferable because the thermal stability of the composition decreases. R₁Well
Or R₂Specifically, a methyl group, an ethyl group,
A phenyl group or the like is preferably used, and the most preferable one is phenyl group.
It is a nyl group.

Further, in the formula (I), X represents a linear or branched alkylene group having 2 to 6 carbon atoms, and an ethylene group is preferable. To impart desired properties to the resin composition of the present invention according to its purpose,
Known additives, such as flame retardants other than the above components, flame retardant aids, lubricants, nucleating agents, release agents, antistatic agents, surfactants, colorants, heat stabilizers, UV stabilizers, etc. are added. It is also possible. The polyethylene terephthalate resin composition of the present invention can be easily adjusted by known equipment and methods generally used as a method for adjusting a conventional resin composition,
A method of melt-kneading with an extruder is preferable.

[0017]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples without departing from the gist thereof. The measuring methods for evaluating the physical properties shown in this example are as follows. Physical property measurement method Tensile test: Measured in accordance with ASTM-D-638. Izod impact strength: Measured according to ASTM-D-256.

Method of Evaluating Gas Generated During Molding The resin to be evaluated is dried at 130 ° C. for 5 hours or more and then 265 using a screw type injection molding machine having a diameter of 32 mm.
℃, mold temperature 90 ℃, molding cycle: injection 5 seconds, cooling 1
The mold stain was observed when 50 shots were continuously molded with the gas evaluation mold under the condition of 0 second. Severe mold fouling after molding means that a large amount of gas is generated during molding.

[0019]

[Table 1] Judgment of evolved gas ◎ ---- There is almost no mold contamination and the amount of gas is extremely small. ○ ---- Small mold fouling and small amount of gas. △ ---- Staining on the mold and slightly higher gas amount. × −−− A lot of mold stains and a large amount of gas. ×× −−− The mold is heavily soiled and the amount of gas is very large.

Evaluation Method of Dimensional Stability of Molded Article After drying the resin to be evaluated at 130 ° C. for 5 hours or more, 265 using a screw type injection molding machine having a diameter of 32 mm.
℃, mold temperature 90 ℃, molding cycle: injection 5 seconds, cooling 1
100 mm length, 100 mm width, and 3 mm thickness under the condition of 0 seconds
It was molded into a molded product of t. This is left for 24 hours in a 23 ° C. × 65% RH atmosphere, and then heat-treated at 150 ° C. for 0 to 5 hours,
The dimensional change rate after that was determined.

[0021]

[Table 2] Judgment of dimensional change rate ◎ --- Dimension change rate is extremely small. ○ ---- Small dimensional change rate. △ --- Slightly large dimensional change rate. × −−− Large dimensional change rate. XX ---- Dimension change rate is very large.

[0022]

Examples 1-5, Comparative Examples 1-6 Intrinsic viscosity (phenol / 1,1,2,2-tetrachloroethane = 1/1 (weight ratio) mixed solution, 25 ° C.) 0.55 dl / g polyethylene terephthalate Then, various components shown in Table 1 were added in the amounts shown in Table 1 and mixed, and then a diameter of 30 m set at 270 ° C.
A pelletized composition was prepared by melt-kneading with an extruder equipped with an mφ biaxial vent. This pellet is then
After drying at 5 ° C. for 5 hours or more, a test piece was molded by injection molding and various evaluations were performed. The results are shown in Table 1.

[0023]

[Table 3] PEG (a): m-PEG (average molecular weight = 40
0) PEG (b): m-PEG (average molecular weight = 500
0) PEG (c): m-PEG (average molecular weight = 1500
0) PEG (d): m-PEG (average molecular weight = 2500)
0) PEG (e): ph-PEG (average molecular weight = 1500
0) In addition, m-PEG: polyethylene glycol terminated with a methyl group ph-PEG: polyethylene glycol terminated with a phenyl group

[0024]

According to the present invention, it is possible to obtain a composition which is excellent in mechanical properties and dimensional stability and which produces little gas during molding.

Claims (4)

[Claims] 1. (A) Polyethylene terephthalate: 2
0 to 80% by weight, (B) inorganic filler: 0.1 to 60% by weight, (C) alkali metal salt of aromatic compound having one or more phenolic hydroxyl group and one or more carboxyl group in one molecule: 0. 05-20% by weight, and (D) an average molecular weight of at least one terminal represented by the following formula (I) 5,
000-20,000 polyalkylene glycols:
A polyethylene terephthalate resin composition comprising 0.5 to 10% by weight. [Chemical 1] (R ₁ and R _{2 are} hydrogen or an alkyl group or aryl group having 1 to 30 carbon atoms. X: a linear or branched alkylene group having 2 to 6 carbon atoms, provided that R ₁ and R ₂ are hydrogen at the same time. No.) 2. The polyethylene terephthalate resin composition according to claim 1, wherein the inorganic filler (B) is talc. 3. The inorganic filler (B) is 0.1 to 20% by weight.
The polyethylene terephthalate resin composition according to claim 1 or 2, wherein 4. The polyalkylene glycol is polyethylene glycol, as claimed in any one of claims 1 to 3.
The polyethylene terephthalate resin composition described.