JPH0143781B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic polyester composition that can provide molded articles with excellent mechanical properties, including impact resistance and flexural modulus, thermal properties, anisotropy, and appearance. Polyethylene terephthalate has traditionally been used as a fiber,
It is used in various fields such as films and various molded products, but compared to polybutylene terephthalate, which is the same thermoplastic polyester, it has advantages such as a higher secondary transition point and melting point, but on the other hand, it has a lower crystallization rate. Due to the slowness, there is a problem that, for example, when applied to injection molding, the molding cycle is long and a molded product with sufficiently advanced crystallization and good appearance cannot be obtained. The present inventor added 4 to polyethylene terephthalate.
A copolymerized polyester made by copolymerizing a specific amount of 4'-diphenyl dicarboxylic acid has a heat distortion temperature and appearance comparable to or higher than that of polyethylene terephthalate itself, and has moldability and shape comparable to that of polybutylene terephthalate. It has previously been found that this gives molded articles with stability. However, molded products made of this copolyester not only have lower impact resistance than polybutylene terephthalate, but also are oriented during molding, so for example, the bending elastic modulus in the flow direction of the polymer and the bending elastic modulus in the direction perpendicular to the flow are different. It was found that the difference was significant and that it had the disadvantage of large anisotropy. Furthermore, when additives such as glass fiber are added to this copolyester, there is a problem in that the melt extrusion stability is poor and good stringiness cannot be obtained. Therefore, the present inventors have improved the impact resistance and anisotropy of the copolymerized polyester, and created a polyester composition that can provide excellent molded products with balanced mechanical properties, thermal properties, anisotropy, and appearance. As a result of the study for the purpose of acquisition, we found that by blending a specific amount of a specific olefin copolymer with the above copolymerized polyester, it meets the above purpose and also has excellent extrusion stability when containing additives. It has been found that a thermoplastic polyester composition can be obtained. That is, the present invention uses 100 parts by weight of a copolyester consisting of 30 to 40 mol% of polyethylene terephthalate units and/or polyethylene isophthalate units and 80 to 70 mol% of polyethylene-4,4'-diphenyl dicarboxylate units, α
- Provides a thermoplastic polyester composition comprising 0.5 to 30 parts by weight of an olefin copolymer comprising an olefin and a glycidyl ester of an α,β-unsaturated acid. The copolymerized polyester used in the present invention refers to polyethylene terephthalate units and/or polyethylene isophthalate units and polyethylene-4,
The main skeleton is 4'-diphenyldicarboxylate units. Here, the molar ratio of polyethylene terephthalate and/or polyethylene isophthalate units to polyethylene-4,4'-diphenyldicarboxylate units is 30 to 40 to 70 to 60.
Polyethylene-
70 4,4'-diphenyldicarboxylate units
If the amount is less than mol%, the melting point of the copolyester will be lower than that of polyethylene terephthalate, and the crystallization rate and mechanical properties will also decrease, which is not preferable. Moreover, if the polyethylene-4,4'-diphenyl dicarboxylate unit is 80 mol% or more, the melting point and melt viscosity of the copolymerized polyester will become considerably high, making it difficult to obtain this polymer by ordinary melt polymerization, which is not preferable. . By making the above copolymerization composition of polyethylene terephthalate and/or polyethylene isophthalate units and polyethylene-4,4'-diphenyldicarboxylate units, it is possible to achieve a polyethylene terephthalate and/or polyethylene isophthalate unit with a melting point of 260 to 300°C and a crystallization rate of A copolyester that is larger than terephthalate and has excellent mechanical and thermal properties can be obtained. The above-mentioned copolymerized polyester has 4,4'-diphenyldicarboxylic acid, terephthalic acid and/or isophthalic acid, and ethylene glycol as main components, but it also contains hexahydroterephthalic acid, 1,2-bis(4 -carboxyphenoxy)ethane, 3,3'-diphenyldicarboxylic acid, 3,4'-diphenyldicarboxylic acid, 2,2'-
Other acid components such as diphenyl dicarboxylic acid and 2,6-naphthalene dicarboxylic acid, and 1,4-butanediol, neopentyl glycol, diethylene glycol, 2,2-bis(4-β-hydroxyethoxyphenyl) sulfone, etc. Other glycol components can be included in small amounts as copolymer components. There are no particular restrictions on the polycondensation conditions for the copolymerized polyester, and the polycondensation conditions can be similar to those for ordinary polyethylene terephthalate or polybutylene terephthalate. In addition, the copolyester used should have a solid phase viscosity (measured in orthochlorophenol at 35°C) in the range of 0.5 to 1.8 in terms of mechanical properties and melt viscosity, and in terms of its hydrolysis resistance. It is preferable that the carboxy terminal amount is 45 equivalents/ton or less. The α-olefin in the olefin copolymer comprising α-olefin and glycidyl ester of α,β-unsaturated acid used in the present invention is ethylene, propylene, butene-1, etc., but ethylene is preferably used. . In addition, glycidyl ester of α,β-unsaturated acid has the general formula (In the formula, R is a hydrogen atom or a lower alkyl group.) Specifically, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, etc., with glycidyl methacrylate being preferably used. . The amount of copolymerized glycidyl ester of α,β-unsaturated acid is suitably in the range of 1 to 50% by weight. Furthermore, an unsaturated monomer that can be copolymerized with the above copolymer if it is 40% by weight or less,
For example, vinyl ethers, vinyl esters such as vinyl acetate and vinyl propionate, methyl,
Acrylic acid and methacrylic acid esters such as ethyl and propyl, acrylonitrile, styrene, etc. may be copolymerized. The blending amount of the above olefin copolymer is 0.5 to 30 parts by weight per 100 parts by weight of the copolyester,
In particular, 5 to 20 parts by weight is appropriate; if it is less than 0.5 parts by weight, a molded product with insufficient impact resistance and anisotropy will be obtained, and if it is more than 30 parts by weight, the elastic modulus and thermal properties of the molded product will be poor. This is not preferable because the deformation temperature decreases. There are no particular restrictions on the method of blending the above-mentioned copolyester and olefin copolymer; for example, they may be premixed or separately fed to an extruder,
A method such as melting and mixing can be adopted. When mixing the copolyester and the olefin copolymer, use the usual plastic additives, such as fibrous reinforcing agents such as glass fiber and asbestos fiber, fillers such as glass powder and glass beads, talc, and stearin. Crystallization accelerators such as acid metal salts, mold release agents such as montanic acid glycol esters and bisamides, stabilizers such as hindered phenol compounds, organic phosphites, hexabrombenzene, decabrom diphenyl, decabrom diphenyl ether , antimony trioxide, brominated polystyrene, etc., pigments such as titanium oxide, dyes, etc. can be added in required amounts. In addition, small amounts of other thermoplastic resins (e.g. polyethylene, polypropylene, acrylic resins, fluorine resins, polyamides, polyacetals, polycarbonates, polysulfones, polyphenylene oxides, etc.), thermosetting resins (e.g. phenolic resins,
At least one of melamine resin, polyester resin, silicone resin, epoxy resin, etc.) and soft thermoplastic resin (eg, ethylene/vinyl acetate copolymer, polyester elastomer, ethylene/propylene terpolymer, etc.) can also be added. In particular, when blending fibrous reinforcing agents such as glass fibers and fillers with the copolymerized polyester, the additives are bulky and have poor affinity with the polymer, making it difficult for them to get caught in the extruder or melt. Although the extrusion stability is poor, the addition of the olefin copolymer improves the extrusion stability and has the additional effect of increasing the yield of good guts. The thermoplastic polyester composition of the present invention can be applied to ordinary molding methods such as injection molding, extrusion molding, blow molding, compression molding, etc. In particular, molded products obtained by injection molding have good impact resistance and bending elasticity. It has well-balanced mechanical properties such as modulus, thermal properties typified by heat distortion temperature, anisotropy of mechanical properties, and appearance, making it useful for a variety of applications. The present invention will be further explained below with reference to Examples. Note that the numbers in the examples indicate parts by weight. Example 1 Ethylene-glycidyl methacrylate (90/10 weight ratio) was added to 100 parts of a copolyester consisting of polyethylene terephthalate units and polyethylene-4,4'-diphenyldicarboxylate in the molar ratio shown in Table 1. The copolymers were dry blended in the proportions shown in Table 1, melt-mixed using an extruder, the mixture was extruded in a gut shape, cooled, and then pelletized using a strand cutter. Each pellet was subjected to a 5-ounce screw in-line injection molding machine, and the mold temperature was 140°C.
An 80 mm square plate and a test piece for measuring heat deformation temperature were molded. For each test piece, the Izot impact strength was determined according to ASTM D-256, the flexural modulus was determined according to ASTM D-790, and the flexural modulus was determined according to ASTM D-648 (18.6 kg/
cm ² ), the heat distortion temperature was measured. The anisotropy was evaluated by cutting the square plate to a width of 12 mm in the flow direction and in the direction perpendicular to the flow, and measuring the flexural modulus of both. The appearance of the molded product was observed with the naked eye, A: Very good, B;
Good, C; poor was used as the criterion. These results are shown in Table 1. For comparison, Table 1 also shows the physical property measurement results for test pieces made of polybutylene terephthalate.

[Table] As is clear from the results in Table 1, the molded products (Nos. 1 to 4) obtained from the compositions of the present invention have high impact resistance and heat distortion temperature, and also have extremely high anisotropy and appearance. In good condition. On the other hand, when the olefin copolymer is not blended (No. 5) and when the amount blended is small (No.
6) has low impact resistance and large anisotropy. Furthermore, if the polyethylene-4,4'-dicarboxylate unit content of the copolyester is less than 50 mol% (No. 7), even if an olefin copolymer is blended, the heat distortion temperature will be low and only molded products with poor appearance will be obtained. I can't. Note that the polybutylene terephthalate molded article (No. 8) has inferior mechanical properties and a significantly lower heat distortion temperature than the molded article made of the composition of the present invention. Example 2 Ethylene-glycidyl methacrylate ( 90/10 weight ratio) copolymer and glass fiber tip strands with a length of 3 mm were dry blended in the proportions shown in Table 1,
The mixture was melt-mixed using a screw extruder set at 280 to 290° C., and the mixture was extruded in a gut shape, cooled, and then pelletized using a strand cutter. At this time, the ratio (%) of pelletizable guts to the total guts was determined and used as a measure of melt extrusion stability. Next, each pellet was subjected to a 5-ounce screw in-line injection molding machine set at 280 to 300°C, and a test piece similar to that in Example 1 was molded at a mold temperature of 140°C, and its characteristics were evaluated. . The results are shown in Table 2.

[Table] As is clear from the results in Table 2, blending the olefin copolymer greatly improves the melt extrusion stability when blending glass fibers, and also improves the impact resistance and anisotropy of the molded product. and the appearance can be significantly improved.

Claims (1)

[Claims] 1. α-olefin is added to 100 parts by weight of a copolyester consisting of 30 to 40 mol% of polyethylene terephthalate units and/or polyethylene isophthalate units and 70 to 60 mol% of polyethylene-4,4'-diphenyldicarboxylate units. and 0.5 to 30 parts by weight of an olefinic copolymer consisting of glycidyl ester of an α,β-unsaturated acid.