JPH0565540B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a polyester resin composition with excellent moldability. More specifically, the present invention relates to a molding polyester resin composition with improved crystallization rate. BACKGROUND ART Polyester, particularly polyethylene terephthalate, has excellent properties and is useful as a material for fibers, films, and other molded products, and is widely used industrially. However, such polyethylene terephthalate has a slow crystallization rate to be used as non-oriented molded products other than fibers and films, and requires cooling for a long time at a mold temperature of over 140°C, especially when injection molding. There are drawbacks. Various methods have been proposed in the past in order to improve these drawbacks. For example,
-7542 and Japanese Patent Publication No. 48-4097 disclose a method of blending a crystal nucleating agent consisting of inorganic solid particles, of which talc is a typical example, and a method of blending an alkali metal salt of an organic carboxylic acid. ing. In any of these methods, the crystal nucleating agent blended has the effect of increasing the crystallization rate in a high temperature range of around 200°C, but this effect is hardly observed in a low temperature range. Further, Japanese Patent Publication No. 55-47058 discloses a composition in which polyethylene terephthalate is blended with glass fiber, an ionomer, neopentyl glycol benzoate, and the like. Such a composition promotes the crystallization of polyethylene terephthalate at low temperatures, but when a molding material made of this composition is used as an injection material, mold deposits are observed in the mold cavity, and melting occurs. If the temperature exceeds 275℃, resin burn will occur. Furthermore, when drying the molding material with a normal hopper dryer, the components in the composition evaporate at the drying temperature of normal polyethylene terephthalate (110 to 190°C), which impairs the performance and ease of handling of the molded product. At present, further improvements are desired. Problems to be Solved by the Invention The present invention solves the problem that when conventional polyethylene terephthalate is used as a molded product, the crystallization rate is slow, and especially when injection molding, cooling is required for a long time, or molding is difficult. Eliminates the conventional problem of slow crystallization speed in low temperature range,
The object of the present invention is to provide a polyester resin composition for molding that has an improved crystallization rate. Means for Solving the Problems The present inventors have conducted intensive research to solve the problems of polyethylene terephthalate as described above.
The resin composition of the present invention was obtained by the following means. That is, the polyester resin composition according to the present invention contains 100 parts by weight of polyethylene terephthalate or a polyester having at least 80 mol% or more of ethylene terephthalate repeating units (A), and 5 to 75 mol% of an acyloxyaromatic carboxylic acid.
Copolymerized polyethylene terephthalate
This is a polyester resin composition containing 0.5 to 25 parts by weight of component (B). The polyester of component (A) used in the present invention is polyethylene terephthalate or a polyester containing at least 80 mol% or more, preferably 90 mol% or more of ethylene terephthalate repeating units. Other acid components and/or glycol components may be copolymerized. The above-mentioned polyester can be manufactured by a conventional manufacturing method, for example, by performing an esterification reaction with terephthalic acid and ethylene glycol, followed by a polycondensation reaction. The acyloxy aromatic carboxylic acid copolymerized polyester of component (B) used in the present invention is a polyester whose main acid component is aromatic dicarboxylic acid and whose main glycol component is alkylene glycol, and which is copolymerized with acyloxy aromatic carboxylic acid. It is a copolymerized polyester. Examples of acyloxyaromatic carboxylic acids used here include p-acetoxybenzoic acid, m-
Acetoxybenzoic acid, 4-acetoxy-3-methoxybenzoic acid, 4-acetoxy-3-chlorobenzoic acid, 4-acetoxy-3,5-dichlorobenzoic acid, P-(p-acetoxyphenyl)benzoic acid and P- Examples include (p-acetoxyphenylfonyl)benzoic acid, and among these, p-acetoxybenzoic acid is particularly preferred. The copolymerization amount of the above copolymerizable compound is 5 to 75 mol%, preferably 10 to 70 mol%. If it is less than 5 mol %, the effect will be small, and if it exceeds 75 mol %, the melting temperature will be high, making it impossible to flow well and making molding very difficult. Furthermore, any method may be employed to produce copolymerized polyethylene terephthalate obtained by copolymerizing the above copolymerized compound. Usually, the polycondensation reaction may be completed under reduced pressure after acidolysis of the raw material polyester with a predetermined amount of acyloxy aromatic carboxylic acid. The copolymerized polyester thus obtained may further be copolymerized with a small amount (usually 20 mol % or less) of an acid component other than terephthalic acid and ethylene glycol and/or a glycol component, if necessary. In the present invention, the blending amount of the copolymerized polyester as component (B) was determined by taking into account the effects achieved by blending, the loss of the excellent properties inherent to the polyester resin due to excessive blending, and problems in molding (particularly a decrease in fluidity, etc.). 0.5 to 25 per 100 parts by weight of polyester resin
parts by weight, preferably 1.0 to 20 parts by weight. If the blending amount is less than 0.5 part by weight, the effect will not be sufficiently expressed and only unsatisfactory molded products will be obtained. On the other hand, if it exceeds 20 parts by weight, the melt flowability of the resin composition will be poor, making it impossible to obtain a molded product with a good appearance, and furthermore, the effect will reach saturation, unnecessarily impairing the performance of polyethylene terephthalate. That's all. In addition to the above components, the resin composition of the present invention includes:
A crystal nucleating agent and a reinforcing agent may also be blended. Such crystal nucleating agents include, for example, inorganic solids such as talc, kaolin, mica, and monocarboxylic or dicarboxylic acids such as sodium stearate, sodium acetate, and lithium terephthalate. Examples of reinforcing agents include fibrous substances such as glass fibers, carbon fibers, and asbestos fibers. When these crystal nucleating agents and reinforcing agents are used in combination with the above-mentioned resin composition, they have the effect of imparting shape stability to the molded article made of the resin composition according to the present invention, and at the same time improve heat resistance and mechanical properties. This results in improved results. The resin composition of the present invention can be produced by any commonly used method. For example, polyester, a crystal nucleating agent, and a reinforcing agent are mixed in a mixer, dried, and then melt extruded using an extruder.
Component (B) may be dry blended during molding,
Alternatively, all the components may be dry mixed and then melt-extruded using an extruder. The resin composition of the present invention may contain various additives that are conventionally commonly used depending on the purpose and purpose, such as oxidation stabilizers, ultraviolet absorbers, lubricants, mold release agents, flame retardants, antistatic agents, A coloring agent or the like may be added. The polyester resin composition obtained as described above has the advantage of having a high crystallization rate and being able to be molded at low temperatures. Note that JP-A No. 55-106222 discloses a method for producing polyalkylene terephthalate modified with oxyaromatic carboxylic acid, and states that it may be mixed with other polyesters. To achieve this purpose, it is necessary to use an acyloxyaromatic carboxylic acid as a modifier. Additionally, JP-A-49-72393 discloses a method for producing a copolyester using an alkylcarbonyloxyaromatic carboxylic acid as a modifier, but there is no description suggesting the structure and effects of the present invention. . Examples Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but it goes without saying that the technical scope of the present invention is not limited by these Examples. (1) In the examples, [η] is 30% by a mixed solvent solution of phenol/tetrachloroethane (6/4 weight ratio).
It is the intrinsic viscosity of the polymer when measured in °C. (2) The crystallization rate was measured using a differential calorimeter (Model 2 manufactured by PerkinElmer), which is well known in the industry. The measurement method is to weigh out approximately 10 mg of a sample that has been quenched and solidified with cooling water after melt extrusion, and measure it at a heating rate of 16°C/min. The peak temperature (Tc ₁ ) of the crystallization exothermic peak and the dissolution endothermic peak peak temperature (Tm), and after further holding at 300℃ for 10 minutes, 16
The apex temperature (Tc ₂ ) of the crystallization exothermic peak obtained by measuring at a cooling rate of °C/min is also shown.
Further, the ratio between the height b of the exothermic peak of cooling crystallization and the width a of the peak at the baseline is expressed as b/a. The lower the temperature is for Tc ₁ , the higher the temperature is for Tc ₂ ,
It is considered that the larger b/a is, the faster the crystallization rate is. Examples 1 to 7, Comparative Examples 1 to 5 [η] = 0.68 polyethylene terephthalate 100
After dry-blending a predetermined amount of acyloxyaromatic carboxylic acid copolymerized polyethylene terephthalate shown in Table 1 based on the weight part, drying was carried out at 130°C for 5 hours under reduced pressure. The mixture was melt-mixed at a temperature of 270-280-280°C, and the resulting strands were cooled with water and cut into pellets. The crystallization behavior of this pellet was measured using the method described above. Table 1 shows the results.
Shown below. Furthermore, talc ("MS") was added to 100 parts by weight of the polyester resin compositions obtained in Examples and Comparative Examples.
After weighing 1 part by weight of "type" Nippon Talc Co., Ltd. and 45 parts by weight of a 3 mm long glass tip strand ("MA 429S" made by Asahi Fiber Glass Co., Ltd.), they were mixed in a rotary drum blender. Next, this was heated to a cylinder temperature of 270-280° using a 35mmφ vented twin-screw extruder.
The mixture was melted and mixed at 280°C, and the resulting strands were cooled with water and cut into pellets. After drying the obtained pellets under reduced pressure at 130°C for 5 hours, the barrel temperature was 270-280-280°C and the injection pressure was 300-500 using an injection molding machine (PLASTAR S-50 manufactured by Toyo Machinery & Metals Co., Ltd.).
ASTM No. 1 dumbbell test pieces were molded under the following conditions: Kg/cm ² , cooling time 15 seconds, molding cycle 30 seconds, and mold temperature 100°C. The surface gloss was determined by observing the surface of the test piece, and the mold releasability was expressed as the drop rate after ejection from the mold for 50 consecutive shots. Further, bending strength was measured according to ASTM D790. The results are shown in Table 2 (symbols T to X are comparative examples). In Table 1, the acyloxyaromatic carboxylic acid copolyester was synthesized as follows. Polyethylene terephthalate with [η] = 0.85 and acyloxy aromatic carboxylic acid having a predetermined copolymerization amount were heated and stirred under normal pressure at a temperature of 270°C for 2 hours to proceed with acidolysis, and the acetic acid removal reached 97% of the theoretical amount. At that point, it was transferred to a polycondensation reaction tank under nitrogen pressure,
A polycondensation reaction was carried out at a temperature of 280°C and a pressure of 0.1 mmHg for 12 hours to form pellets.

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【table】

[Table] Effects of the Invention The polyester resin composition obtained by the present invention has a higher crystallization rate than conventional polyester resin compositions, can be molded at low temperatures, and has excellent surface gloss. This makes it possible to provide molded products having the following characteristics, and it has extremely high potential as a molding material.

Claims (1)

[Claims] 1 Copolymerized polyethylene terephthalate 0.5 to 25% by copolymerizing 5 to 75 mol% of acyloxy aromatic carboxylic acid to 100 parts by weight of polyethylene terephthalate or a polyester having at least 80 mol% or more of ethylene terephthalate repeating units.
A polyester resin composition formed by blending parts by weight.