JP2001316577A - Thermoplastic polyester resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic polyester resin composition having small resistance to mold release and high productivity in molding process. SOLUTION: This thermoplastic polyester resin composition is characterized in that resistance to mold release of a cylindrical molded product is <=20N at 50-140 deg.C surface temperature of a mold in injection molding. The thermoplastic polyester resin composition comprises (A) 100 pts.wt. polyester resin consisting mainly of recurring units of ethylene terephthalate, (B) 0.1-30 pts.wt. polyalkylene terephthalate resin having <=5,000 molecular weight other than the above polyester resin, (C) 0.01-2 pts.wt. 26-32C aliphatic carboxylic acid or its derivative and (D) 0-150 pts.wt. inorganic reinforcing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thermoplastic polyester resin composition having excellent moldability in injection molding and high productivity in a molding step.

[0002]

2. Description of the Related Art In general, polyethylene terephthalate resin (hereinafter referred to as PET) is widely used for electric / electronic parts and automobile parts because of its excellent mechanical properties, heat resistance, electric properties, and chemical resistance. I have. However, in the molding process, there are problems such as deformation of the product due to the mold temperature depending on the mold temperature at the time of molding, and a long molding cycle, and the moldability is important in terms of productivity and economy. Is a factor.

Hitherto, polyethylene wax, esters of higher fatty acids and metal salts of higher fatty acids have been used to improve the moldability of molding materials. However, since the thermoplastic polyester and these template agents are poor in compatibility, the amount of the thermoplastic polyester added is limited in terms of the appearance of the molded article. Also, depending on the mold temperature during molding, there is a temperature range with poor moldability, so a crystallization accelerator is added to increase the crystallization speed at low temperatures, and the mold temperature which is normally required to be 120 to 150 ° C is lower. Although the moldability at a low temperature is slightly improved by crystallization at a low temperature, there is a limit to the improvement in altitude.

[0004]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a mold having good moldability and little deformation during the mold while maintaining the high physical properties and appearance of the thermoplastic polyester. It is an object to provide a thermoplastic polyester resin composition having a wide range.

[0005]

Means for Solving the Problems The present inventors have intensively studied and studied to achieve the above object, and as a result, have found that a specific polyalkylene terephthalate resin having a molecular weight of 5,000 or less and a carbon number of 26 effective as a template agent. If a combination of ~ 32 aliphatic carboxylic acids or their derivatives is used, the mold resistance during injection molding is small, stable over a wide range of mold temperature range, and the thermoplastic polyester resin can shorten the molding cycle further Was finally obtained, and the present invention was finally completed. That is, the present invention provides a mold surface temperature of 50 to 140 during injection molding, which is measured under measurement conditions described below.
A thermoplastic polyester resin composition characterized in that the cylindrical molded product at 20 ° C has a template low resistance value of 20 N or less.
The molecular weight is 5,000 based on 100 parts by weight of a polyester resin (A) having ethylene terephthalate as a repeating unit.
The following polyalkylene terephthalate resin other than the polyester resin (A) (B) 0.1 to 30 parts by weight, an aliphatic carboxylic acid having 26 to 32 carbon atoms or a derivative thereof (C) 0.01 to 2 parts by weight,
The thermoplastic polyester resin composition as described above, comprising 0 to 150 parts by weight of the inorganic reinforcing material (D).

The polyester resin (A) mainly having ethylene terephthalate as a repeating unit used in the present invention
As polyethylene terephthalate and / or 8
A polyethylene terephthalate copolymer containing 0 mol% or more of ethylene terephthalate is used. Examples of the copolymerized glycol component other than ethylene glycol include propylene glycol, butanediol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol, diethylene glycol, polyethylene glycol, polytetramethylene glycol, polylactone, and the like. As the acid component other than terephthalic acid, a known acid component can be copolymerized. For example, naphthalenedicarboxylic acid, isophthalic acid, adipic acid, sebacic acid and the like are used. When the amount of the copolymer component exceeds 20 mol%, heat resistance and crystallinity are lowered, which is not preferable for this use.

[0007] The polyester resin (A) preferably has a molecular weight of more than 5000, and a mixed solvent of phenol and tetrachloroethane in a weight ratio of 6: 4 is used.
The reduced specific viscosity at a concentration of 0.4 g / d1 at 0.4 ° C is 0.4 or more, preferably
0.5 or more. If the reduced specific viscosity is less than 0.4, the impact resistance is lowered, which is not preferable.

The molecular weight of the composition of the present invention is
5000 or less polyalkylene terephthalate resin (B),
0.1 to 30 parts by weight, preferably 0.2 to 15 parts by weight, particularly preferably 100 parts by weight of the polyester resin (A),
0.5 to 10 parts by weight are blended. If the amount is less than 0.1 part by weight, the effect is small, and if it exceeds 30 parts by weight, the mechanical properties deteriorate, which is not preferable. Although the reason why the specific polyalkylene terephthalate exhibits a high template effect is not clear, it is considered that when the specific polyalkylene terephthalate is blended with the polyethylene terephthalate-based resin, it easily precipitates on the surface of the mold and the molded article due to the difference in viscosity. .

As the polyalkylene terephthalate resin (B) having a molecular weight of 5,000 or less, specifically, polybutylene terephthalate and polypropylene terephthalate are preferable. Further, at least one terminal is preferably a hydrocarbon group having 6 or more carbon atoms. This is done by esterification using monofunctional higher fatty acids or higher alcohols,
It is carried out by a method such as adding 6 or more glycidyl ethers, monooxazoline or monoisocyanate to a carbosyl group or a hydroxyl group. Specifically, it is esterified with 2-ethylhexyl alcohol, lauryl alcohol, stearyl alcohol, lauric acid, stearic acid, montanic acid, or lauryl glycidyl ether, styryl glycidyl ether, 2-ethylhexyl oxazoline, lauryl oxazoline, lauryl isocyanate,
It is obtained by an addition reaction of phenyl isocyanate. The terminal ratio of the hydrocarbon group having 6 or more carbon atoms is required to be 50 mol% or more, and is preferably 75 mol% or more. The hydrocarbon group has 6 carbon atoms
The number is preferably 8 or more. If the number of carbon atoms is less than 6, the effect of improving template properties is undesirably reduced. In addition,
The molecular weight of the polyalkylene terephthalate used in the present invention is 5,000 or less. Exceeding this value is not preferred because the effect of improving the moldability is reduced.

Next, the composition of the present invention contains 26 to 26 carbon atoms.
Examples of the aliphatic carboxylic acid 32 or its derivative (C) include montanic acid, cerotic acid, and melicic acid, and an ester of the carboxylic acid with an aliphatic dihydric alcohol and a partially saponified product thereof. Preferred are those obtained by esterifying montanic acid wax with a dihydric alcohol and esters of montan wax acid partially saponified with calcium. As a compounding amount, 0.01-2
Parts by weight. If it is less than this, it is difficult to form a template at the time of molding, and if it is more than this, the surface appearance of the molded article is undesirably deteriorated.

In the present invention, 150 parts by weight of an inorganic reinforcing material (D) is blended with 100 parts by weight of the polyester resin (A) depending on the use. If it exceeds 150 parts by weight, the fluidity and the appearance of the molded product are undesirably reduced. As inorganic reinforcement,
Fibrous reinforcing materials such as glass fiber, carbon fiber and aramid fiber, needle-like crystals such as potassium titanate and aluminum borate, glass beads, silica, talc, mica, calcium carbonate, wollastonite, kaolin, clay, and oxidation Examples include magnesium and alumina oxide. Among them, glass fiber, talc, wollastonite, mica, calcium carbonate and combinations thereof are preferred. As these reinforcing materials, an epoxy silane coupling agent, an amino silane coupling agent, a titanate coupling agent, or the like may be used in order to improve the adhesion to the polyethylene terephthalate resin, that is, to improve the strength and impact strength.

Further, the thermoplastic polyester resin composition of the present invention may be used in combination with a general template, for example, a metal salt or ester of a higher fatty acid. Further, other conventional additives such as a heat stabilizer, a weathering agent, a hydrolysis stabilizer, and a pigment may be added. Examples of the heat stabilizer include hindered phenol type, thioether type / phosphite type, and combinations thereof. Examples of the weathering agent include carbon black, benzophenone, triazole, and hindered amine. Examples of the hydrolysis resistant agent include carbodiimide, bisoxazoline, epoxy, and isocyanate compounds. As the pigment, a conventional heat-resistant pigment for polyethylene terephthalate can be used.

As described above, the composition of the present invention having such a constitution has a release resistance of 20 N or less, preferably 18 N or less, and particularly preferably 15 N or less, according to a measuring method described later. The resin composition of the present invention is produced by kneading the above-mentioned components using a single-screw extruder, a twin-screw extruder, or a kneader. There is no particular limitation on the type of kneader used and the kneading conditions. The molding method is not particularly limited, but injection molding is generally used.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A molded article obtained from the composition of the present invention may be colored by original coating or coloring in which a pigment is mixed with a molding material, or may be subjected to secondary bonding by a method such as bolting, ultrasonic welding or vibration welding. It is processed and used as various molded articles. Specifically, it can be used for electric and electronic parts such as coil bobbins, switches, relay bases, connectors and the like, and automotive parts such as air flow meters, air pumps, bobbins, coil cases, sensor housings, gear cases and the like.

[0015]

The present invention will be specifically described below with reference to examples. The evaluation of physical properties in the present invention was measured by the following methods. 1) Template resistance: equipped with a pressure sensor that detects low drag when the molded product is ejected from the mold with an ejector pin.
Use a cylindrical molded die with an outer diameter of 40 mm, an inner diameter of 34 mm, a height of 50 mm and a taper of 2 °, and adjust the surface temperature of the die to 50,80,100,120,14
The temperature was adjusted to 0 ° C., and the template resistance value during injection molding was measured. (Molding conditions) Injection molding machine: Niigata NN-75 Cylinder temperature: 270-270-270-265 ℃ Injection pressure: 60Mpa Injection time: 18 seconds Cooling time: 20 seconds 2) Molding cycle time: 2mm thick 100x100x30mm box The shortest cycle time in which a molded product could be modeled with four 5φ protruding pins was measured. (Molding conditions) Injection molding machine: Toshiba IS-100N Cylinder temperature: 265-270-270-265 ℃ Mold temperature: 120 ℃ Injection pressure: 80Mpa Injection time: 8 seconds Cooling time: 20 seconds 3) Molded product appearance: 170x150mm Was injection molded, and the degree of surface unevenness was observed. ○: uniform, △: less than 5% of non-uniform part, ×: more than 5% of non-uniform part (Molding condition) Injection molding machine: Toshiba IS-80EN Cylinder temperature: 265-270-270-265 ℃ Mold temperature: 120 ℃ Injection pressure: 45Mpa Injection time 17 seconds Cooling time: 20 seconds

Examples 1 to 9 and Comparative Examples 1 to 7 A predetermined amount of each of the thermoplastic polyester resin, hydrocarbon group-terminated polyalkylene terephthalate and inorganic reinforcing material shown in Table 1 was measured and premixed. The premix was adjusted to a cylinder temperature of 265-270-270 ° C. from the hopper side.
The mixture was put into a hopper of a 5φ same-direction twin-screw extruder and melt-kneaded at a screw rotation speed of 100 rpm to obtain pellets. The pellets were pre-dried at 130 ° C. for 4 hours, and the moldability, molding cycle, and appearance of the molded product were measured and evaluated. The results are shown in Table 1.

[0017]

[Table 1] As is clear from Table 1, it is understood that the thermoplastic polyester resin composition of the present invention has a small template resistance, a short molding cycle time, and excellent productivity in the molding step.

[0018]

As is clear from Table 1 above, the thermoplastic polyester resin composition of the present invention has a small template resistance of 20 N or less, a molding cycle time of 45 seconds or less, and an excellent appearance of a molded product. You can see that there is. Therefore, the present invention has a small template resistance and a short molding cycle time, so that the productivity is high and the processing cost can be reduced, which greatly contributes to the industry.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a measuring device used to measure a template resistance of resin compositions manufactured in Examples and Comparative Examples.

[Explanation of symbols]

 1: Nozzle 2: Subaru runner 3: Molded product (cylindrical type) 4: Ejector pin 5: Ejector plate 6: Pressure sensor (made by Dainisco) 7: Ejector rod 8: Cavity 9: Core 1O: Model resistance recorder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 67:00 B29K 67:00 F term (Reference) 4F071 AA45 AA46 AB01 AC09 AC10 AE17 AF53 AH07 AH12 BB05 BC04 4F206 AA24 AB07 AB11 AB19 JA07 JF01 JF02 JN41 4J002 CF052 CF061 CF072 CF272 CL063 DA017 DE077 DE147 DE187 DE237 DJ007 DJ017 DJ037 DJ047 DJ057 DK007 DL007 EF056 EH036 FA043 FA047 FD013 FD017 GN00 GQ01

Claims (2)

[Claims] 1. A thermoplastic polyester resin composition characterized in that the cylindrical mold has a low mold resistance of 20 N or less at a mold surface temperature of 50 to 140 ° C. during injection molding. 2. 100 parts by weight of a polyester resin (A) having ethylene terephthalate as a repeating unit,
Polyalkylene terephthalate resin other than the polyester resin (A) having a molecular weight of 5000 or less (B) 0.1 to 30 parts by weight, an aliphatic carboxylic acid having 26 to 32 carbon atoms or a derivative thereof (C) 0.0
2. The thermoplastic polyester resin composition according to claim 1, comprising 1 to 2 parts by weight and 0 to 150 parts by weight of an inorganic reinforcing material (D).