JPH0572421B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a filler-reinforced copolyester resin composition suitable for injection molding using an economically low temperature mold of 80° C. or lower. [Prior art and its problems] Polyethylene terephthalate (hereinafter referred to as PET) has excellent heat resistance, chemical resistance, mechanical properties, electrical properties, etc., and is used in many industrial products such as fibers and films. PET sometimes reinforced with inorganic fillers such as glass fiber has significantly improved thermal and mechanical properties compared to polybutylene terephthalate compositions.
Following the lead of polybutylene terephthalate resin compositions, it has recently been widely used in engineering plastics and other applications. However, when filler-reinforced PET is used for injection molding applications, it is known that there are many drawbacks in terms of molding and physical properties due to the crystallization behavior of PET. In other words, since PET has a low crystallization rate at low temperatures, for example 130℃
When injection molding is performed at a mold temperature below, it is difficult to obtain a molded product with good crystallization, and only a molded product with poor surface hardness can be obtained. Moreover, the obtained molded product is
When used at a temperature above the next transition point, crystallization progresses, resulting in poor shape stability. In addition, surface roughness occurs due to non-uniform crystallization within the mold, and this poses many problems as a resin for injection molding. Furthermore, in some cases, molding is performed at a mold temperature of around 50°C to obtain a molded product in which the PET is hardly crystallized, and then heat treatment is performed, but this method is only inefficient. However, it has drawbacks such as crystallization during heat treatment, resulting in volumetric shrinkage and deformation of the molded product. Therefore, PET molding is usually carried out using a special molding machine that can obtain a mold temperature of 130°C or higher, but since such molding machines are not common, the mold temperature commonly used is A PET resin that can be molded well using a molding machine at temperatures below 90-110°C has been desired. Conventionally, various proposals have been made for PET resin compositions having a low-temperature crystallization effect that allows PET crystallization to proceed sufficiently even at a mold temperature of 100° C. or less. For example, Japanese Patent Publication No. 45-26225 proposes a method in which an ionic copolymer consisting of an α-olefin and a salt of an α,β-unsaturated carboxylic acid is added to PET. In addition, the combination of polyalkylene glycol compounds and inorganic fillers such as talc was proposed in 1973.
It is proposed by No. 3027 etc. In addition, combination systems of ionic copolymers, polyalkylene glycol compounds, and inorganic fillers are also available, for example in JP-A-59-22958.
Known by the number. On the other hand, there is also a method to solve the problem by copolymerizing the polyester itself with a branching agent having a trifunctional or higher functional ester forming group and polyalkylene glycol.
Proposed by No. 41222. Furthermore, an attempt to modify PET with a monohydroxy compound containing a polyalkylene glycol and a metal salt of a carboxylic acid has also been disclosed, for example, in JP-A-56-38321.
With such conventional compositions, molded products with good releasability from the mold and good surface appearance may be obtained even at a mold temperature of about 90° C. due to an increase in the crystallization rate. However, when such a composition is used as a mold for molding, the temperature can be adjusted using an economical hot water circulation type temperature control device.
For example, when injection molding is performed using a mold at about 80° C., the molded product has good mold releasability and mechanical strength, but the surface smoothness of the molded product is not necessarily satisfactory. In particular, when compared with reinforced polybutylene terephthalate molded products, the current situation is that there is a significant difference in surface gloss, which poses a problem in that its applications are limited. [Objective of the Invention] The present invention has excellent physical properties such as heat resistance, chemical resistance, mechanical properties, and electrical properties, and is also moldable by injection molding using a mold with an economical temperature of 80°C or less. The object of the present invention is to obtain a polyester resin composition capable of providing a molded article having good surface gloss and good surface gloss. [Structure of the Invention] As a result of extensive research by the present inventors, the best way to solve the above-mentioned problems was achieved by blending a specific substance into a copolyester containing a specific glycol component. That is, the present invention is a copolymer containing (A) a terephthalic acid component, an ethylene glycol component, and a polyalkylene glycol component having an average molecular weight of 400 to 20,000,
100 parts by weight of a copolyester resin containing 1 to 20% by weight of the polyalkylene glycol component based on the copolymer, (B) 10 to 140 parts by weight of a filler reinforcing substance, (C) ethylene and acrylic acid or methacrylic acid. Sodium salt or potassium salt of copolymer of
0.05 to 20 parts by weight (D) General formula R ₁ O (-R ₂ O) - _o R ₁ ′ (However, R ₁ and R ₁ ′ represent H or a lower alkyl group, and R ₂ represents a carbon number of 2 to 4. represents an alkylene group, and n is a number of 5 or more)
This is a copolymerized polyester resin composition containing 0.1 to 10 parts by weight. The copolymerized polyester resin (A) used in the present invention preferably has an intrinsic viscosity of at least 0.4, and the structural units consist of a terephthalic acid component, an ethylene glycol component, and a polyalkylene glycol having an average molecular weight of 400 to 20,000. In the case of filler-reinforced polyester resins, generally when the intrinsic viscosity of the polymer is 0.4 or higher, it exhibits good mechanical properties;
In particular, when the intrinsic viscosity is 0.5 or more, preferably 0.6 or more, a resin with well-balanced mechanical performance can be obtained. The resin composition of the present invention exhibits sufficient effects even when using a polyester resin with a high intrinsic viscosity as described above, and injection molded products with good surface gloss can be obtained at a mold temperature of 80°C or less. . Note that the intrinsic viscosity referred to herein is a value measured at 30° C. in a mixed solvent of phenol/tetrachloroethane at a weight ratio of 1:1. The polyalkylene glycols to be subjected to copolymerization include polyethylene glycol, polypropylene glycol, polybutylene glycol, glycol of a copolymer of ethylene oxide and propylene oxide, or esterification of one end of these with an alkyl group, aryl group, aralyl group, etc. Derivatives bonded by bonds, ether bonds, etc. are used, but polyethylene glycol is best when considering the surface smoothness of the molded product of the resulting polyester resin composition. It is important that the molecular weight of the polyalkylene glycol is in the range of 400 to 20,000. When the average molecular weight of the polyalkylene glycol component is less than 400 or greater than 20,000, not only the surface gloss is not sufficient, but also the heat distortion temperature is lowered, resulting in poor heat resistance.
The preferred average molecular weight is in the range of 400-6000. The proportion of the polyalkylene glycol component in the copolymer is 1 to 20% by weight, preferably 5 to 15% by weight, based on the copolymer. If it is less than 1% by weight, the amount of the polyalkylene glycol compound (D) added later increases, which is undesirable as it causes embossment on the surface of the molded product. If the amount exceeds 20% by weight, the inherent high rigidity of reinforced polyethylene terephthalate will be sacrificed, resulting in a composition that is not suitable for the purpose of the present invention, which is not preferable. Further, the polyester resin used in the present invention may contain components other than the above-mentioned components in an amount of 20 mol% or less. Such copolymerizable components include aromatic dicarboxylic acids such as isophthalic acid and naphthalene dicarboxylic acid, adipic acid,
Aliphatic dicarboxylic acids such as sebacic acid, diols such as diethylene glycol, 1,4-butanediol, neopentyl glycol, 2,2-bis(4-hydroxyphenyl)propane, and oxycarboxylic acids such as p-oxybenzoic acid. etc. can be given. Filler reinforcement material (B) used in the present invention
Examples include talc, clay, kaolin, mica, asbestos, wollastonite, silicates such as calcium silicate, inorganic fillers such as silica, gypsum, and graphite, and glass fibers, carbon fibers, graphite fibers, and metal carbide fibers. , fibrous reinforcing agents such as metal nitride fibers, aramid fibers, and phenolic resin fibers. These filler reinforcing materials may be used alone or in combination of two or more. Further, these may be used as they are, or may be used after surface treatment or sizing agent treatment. The appropriate amount of the filler reinforcing substance (B) to be used is 10 to 140 parts by weight per 100 parts by weight of the polyester resin (A). If it is less than 10 parts by weight, sufficient effects cannot be obtained, and if it exceeds 140 parts by weight, the fluidity of the system becomes poor and molding becomes difficult. Sodium or potassium salts (including both totally and partially neutralized salts) of the copolymers of ethylene and acrylic acid or methacrylic acid used in the present invention (C) Examples include ethylene/acrylic acid copolymer, ethylene/
Examples include sodium salts or potassium salts of methacrylic acid copolymers. Further, the molecular weight of these polymers is preferably 1000 or more, particularly 3000 or more. If the molecular weight is smaller than this range, or if a metal salt of an aliphatic or aromatic carboxylic acid is simply used, the mechanical strength, especially the impact resistance, of the intended resin composition cannot be sufficiently improved. In addition, in the above copolymer, ethylene is 50% of the copolymer.
It is preferable that it accounts for ~98% by weight, and particularly preferably 70-98% by weight. Also, particularly preferred metal salts of polymers are the sodium salts of ethylene/methacrylic acid copolymers and ethylene/acrylic acid copolymers. These compounds may be used alone or in combination of two or more. The amount of component (C) used is 0.05 to 20 parts by weight, preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the polyester resin (A).
10 parts by weight is appropriate. If it exceeds 20 parts by weight, the mechanical properties of the molded product will deteriorate, and if it exceeds 0.05 parts by weight, the effect of improving moldability will be insufficient. The general formula used in the present invention is R ₁ O(-R ₂ O)- _o R ₁ ′ (R ₁ and R ₁ ′ represent H or a lower alkyl group,
R ₂ represents an alkylene group having 2 to 4 carbon atoms. Further, n is a number of 5 or more. ) Polyalkylene glycol compound represented by
Examples of (D) include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and their mono- or dialkyl ethers (for example, monomethyl or dimethyl ether, monoethyl or diethyl ether, monopropyl or dipropyl ether, monobutyl or diptyl ether, etc.) I can do it. In the present invention, it is preferable that the polyalkylene glycol has alkyl ethers at both ends, since the inherent viscosity of the polyester resin during molding is less likely to decrease. If a monoalkyl ether in which only one end is etherified or a polyalkylene glycol in which both ends are hydroxyl groups are used, the intrinsic viscosity of the polyester resin during molding will decrease significantly, so when using these, it is necessary to use a high degree of polymerization. It is necessary to use a polyester resin of The degree of polymerization n of component (D) is preferably 5 or more and 150 or less; if it is less than 5, component (D) tends to stand out on the surface of the molded product, which is not preferred. If it exceeds 150, the surface smoothness and heat resistance of the molded product will not be sufficiently improved. The appropriate amount of component (D) to be used is 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the polyester resin (A). If the amount is more than 10 parts by weight, embossment will occur on the surface of the molded product and the rigidity of the molded product will decrease, and if it is less than 0.1 part by weight, the effect of improving moldability will be insufficient, so it is unsuitable. The composition of the present invention has a high crystallization rate even at relatively low temperatures, so even when molded at an economical mold temperature of 80°C or less, which is usually used for molding general-purpose thermoplastic resins, the composition has a short mold residence time and is uniform throughout the surface layer. Moreover, a molded product that is highly crystallized and has excellent surface gloss can be obtained. The resulting molded product exhibits excellent dimensional stability and shape stability even at high temperatures, minimal warpage, and excellent heat resistance and impact resistance, making it extremely desirable as an engineering plastic material. In the composition of the present invention, in addition to the above-mentioned components, additives commonly used in polyester resins,
For example, it may contain colorants, mold release agents, ultraviolet stabilizers, antioxidants, flame retardants, and the like. Further, other types of polymers may be mixed within a range that does not impair the performance intended by the present invention. In particular, combining PET is preferable because it further increases the utility value of the present invention. The composition of the present invention is produced by mixing each component by any known means. For example, the polyester resin may be mixed with components (B), (C), and (D) in any suitable mixer or rotating machine, and the mixture may be melt extruded or converted into a molten resin in the final stage of polymerization of the polyester resin. Components (B), (C), and (D) can also be mixed and extruded as is. In addition, after melt-kneading components (C) and (D) into polyester resin,
A method of blending component (B) and, conversely, a method of melt-kneading components (C) and (D) with a polyester resin containing component (B) can also be adopted. The composition of the present invention does not require any special molding method or reaction conditions, and can be molded under the same conditions as those used for molding ordinary thermoplastic resins. [Examples of the Invention] The present invention will now be described in more detail with reference to Examples. All parts in the examples are by weight unless otherwise specified. Reference example PET copolymerized with polyalkylene glycol
Production of polyester based polyester 50 kg of dimethyl terephthalate and 35 kg of ethylene glycol were heated in the presence of 22 g of manganese acetate tetrahydrate for 2 hours while stirring at 200°C in a 0.42 m ³ autoclave and distilling off methanol.
After completion of the transesterification reaction, 23 g of Sb ₂ O ₃ , 9 g of phosphoric acid and 4% by weight of polyalkylene glycol and polyalkylene glycol of the type and amount shown in Table 1 (% by weight based on the total copolyester)
An antioxidant (Irukanox 1010, Ciba Geigy sterically hindered phenol) was added. temperature
It was raised to 230°C and kept at this temperature for 30 minutes. The temperature was then further increased to 280°C and the apparatus was then evacuated (10 mmHg). After 30 minutes, reduce the pressure of the device to 0.3mm.
Hg was used to further advance the polycondensation reaction. After 1 hour, the resulting copolyester was stranded through a water bath and granulated. The intrinsic viscosity of this granular material was measured by the method described above. [η] of the obtained granular copolymers was between 0.70 and 0.75. In Table 1, the molecular weight of the polyalkylene glycol was calculated from the terminal hydroxyl value determined based on JIS K 1557. Examples 1 to 6 and Comparative Examples 1 to 3 100 parts of the copolyester obtained in the reference example, a predetermined amount of sodium salt of ethylene/methacrylic acid copolymer (Surlyn 1707, Mitsui Polychem-Kel Co., Ltd.), polyethylene glycol dimethyl ether (of the polyethylene glycol part) average molecular weight 1000), tetrakis[methylene-3(3',
5'-di-t-butyl-4'-hydroxyphenyl)
[Propionate] 0.3 parts of methane (Irganox 1010, Ciba Geigy), 0.7 parts of tri(di-t-butylphenyl) phosphorite (Phosphorite 168, Ciba Geigy), and glass fiber (CS3J-941, Nittobo Co., Ltd., focusing tip) After pre-mixing 50 parts of (cut strand, cut length 3 mm),
40mmφ extruder (8VSE−40−28 manufactured by Osaka Seiki Kozo Co., Ltd.)
The cylinder temperature is 250-
The mixture was melt-kneaded and extruded at 275-275-275°C, an adapter temperature of 265°C, and a die temperature of 265°C to obtain pellets. The extrusion was carried out smoothly and a well-dispersed pellet of glass fibers was obtained. After drying the obtained pellets with hot air at 120°C for 5 hours, the pellets were molded using an injection molding machine (V-15 manufactured by Nippon Steel Ankelberg Co., Ltd.) adjusted to a cylinder temperature of 240-260-280°C, a die temperature of 280°C, and a mold temperature of 80°C. -75 type) to mold the test piece. Table 1 shows the physical properties of the molded product obtained. The surface gloss of the molded piece was measured using an SM color computer model SM-2G manufactured by Suga Test Instruments Co., Ltd.
[Optical conditions: incident angle 60°, acceptance angle 60°, standard plate: flat optically polished glass (black)]. The composition of the present invention exhibited good moldability despite being molded in a mold at a low temperature of 80°C, and had good mold releasability and surface gloss. Furthermore, the heat distortion temperature was higher than that of polybutylene terephthalate resin containing the same amount of glass fiber. The pellets were also used to measure the crystallization temperature (referred to as Tcc) when the pellets were heated from room temperature at 20°C/min using a PerkinElmer DSC-2C differential calorimeter. The lower Tcc means that crystallization progresses more easily even in a lower temperature mold. As shown in Comparative Example 3, when the amount of copolymerized polyalkylene glycol is small, the heat distortion temperature can be considerably high, but there is a drawback that the surface of the molded product has insufficient gloss. Conversely, if the amount of copolymerized polyalkylene glycol exceeds 20% by weight (Comparative Example 2), the surface gloss of the molded product is favorable, but the disadvantage is that the heat distortion temperature becomes lower than that of reinforced polybutylene terephthalate. occurs. If the molecular weight of the polyalkylene glycol to be copolymerized is too small (Comparative Example 1), the desired effects of the present invention will not be achieved. Comparative Example 4 A glass fiber reinforced composition was prepared in the same manner as in Example 2 except that polyethylene glycol dimethyl ether was not added. Table 1 shows the physical properties of the molded product. It can be seen that using polyalkylene glycol copolymerized polyester alone, only molded products with poor surface gloss can be obtained. Comparative Example 5 A glass fiber reinforced composition was prepared in the same manner as in Example 2 except that Surlyn 1707 was not added. Table 1 shows the physical properties of the molded product. It can be seen that only a polyalkylene glycol copolymerized polyester and a polyalkylene glycol compound can yield a molded product with poor surface gloss. Comparative Example 6 Using the same extruder as in the example, 100 parts of polybutylene terephthalate (Novadeur 5010, manufactured by Mitsubishi Chemical Industries, Ltd.) and 43 parts of glass fiber (CS3J-941, manufactured by Nittobo Co., Ltd.), the cylinder temperature was 245-255-255-255°C. ,
The mixture was extruded while melt-kneading at an adapter temperature of 250°C and a die temperature of 250°C to obtain pellets. Furthermore, this pellet
After drying with hot air at 120℃ for 5 hours, the cylinder temperature was 240-250-250℃, the die temperature was 250℃, and the mold temperature was 80℃.
The test specimens were molded with the same molding material as described in Example 1, which was adjusted to . Table 1 shows the physical properties of the molded product obtained. Although glass fiber reinforced polybutylene terephthalate was found to have extremely excellent moldability,
It appears to be inferior to polyethylene terephthalate reinforced with the same glass fiber content in terms of heat distortion temperature.

[Table] Example 7 In Example 3, 14 parts of glass fiber (Nitto Boseki Co., Ltd. CS3J941) and mica (Kuraray Co., Ltd.) were used as fillers.
A composition pellet was prepared and injection molded in the same manner as in Example 3 except that 36 parts of Suzolite 200HK) was used in combination. Table 2 shows the physical properties of the molded product. Comparative Example 7 In Example 3, sodium stearate, which is an aliphatic carboxylic acid metal salt, was used instead of Surlyn 1707.
Pellets of the composition were made and injection molded under the same conditions as in Example 2, except that 0.3 part was used. Table 2 shows the physical properties of the molded product. It can be seen that although the molded product has a preferable surface gloss, its impact resistance is inferior to that of the molded product of Example 3 according to the present invention.

【table】

Claims (1)

[Scope of Claims] 1 (A) A copolymer comprising a terephthalic acid component, an ethylene glycol component, and a polyalkylene glycol component having an average molecular weight of 400 to 20,000, wherein the polyalkylene glycol component is added to the copolymer. (B) 10 to 140 parts by weight of a filler reinforcing substance (C) Sodium salt or potassium salt of a copolymer of ethylene and acrylic acid or methacrylic acid.
0.05 to 20 parts by weight (D) General formula R ₁ O (-R ₂ O) - _o R ₁ ′ (However, R ₁ and R ₁ ′ represent H or a lower alkyl group, and R ₂ represents a carbon number of 2 to 4. A copolymerized polyester resin composition containing 0.1 to 10 parts by weight of a polyalkylene glycol compound represented by the following formula (representing an alkylene group; n is a number of 5 or more).