JPH0465103B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a stabilized composition of a polyester resin and a polycarbonate resin, and more particularly to a thermoplastic resin composition that does not cause strand breakage in the production of the composition and provides molded articles with excellent transparency. Polyethylene terephthalate has excellent properties such as transparency, surface gloss, gas barrier properties, fragrance retention, and chemical resistance, and has an appearance very similar to glass, so it is used for food, cosmetics, medical, etc. It is widely used for containers, films, etc. However, due to its structure, it is highly crystalline and has a high crystallization temperature, so when molded into pipes, rods, sheets, etc., it has poor impact resistance, tensile strength, rigidity, heat resistance, etc. It has the disadvantage that satisfactory practical performance cannot be obtained. Therefore, the current situation is to compensate for the lack of these physical properties by stretching at a high magnification such as by blow molding. However, depending on the shape of the molded product, there may be localized areas with low stretching ratios, and the inherent lack of heat resistance may cause significant deformation during use. There were significant restrictions on the conditions. Conventionally, in order to solve the disadvantages of polyethylene terephthalate, a composition blended with polycarbonate resin, an amorphous polymer with excellent transparency, heat resistance, impact resistance, and tensile strength, was also developed.
It is known from the publication No. 111956. however,
Due to the combination of acid anhydride, the molded products obtained from the composition lose the transparency, which is an excellent feature of polyethylene terephthalate and polycarbonate resins, and also have drawbacks such as the tendency to break the strands during production of the composition. There is. The present inventors have arrived at the present invention as a result of intensive research aimed at solving the above-mentioned drawbacks of polyethylene terephthalate while maintaining as much as possible the excellent transparency of polyethylene terephthalate and polycarbonate resins. That is, the present invention provides a thermoplastic resin composition containing as essential components a polyester resin (A) mainly containing ethylene terephthalate repeating units, a polycarbonate resin (B), and a carboxylic acid or its anhydride (C), The ratio of A) and component (B) is (A):(B)=30~
The weight ratio is 95:70 to 5, and component (C) is 0.005 parts by weight or more based on the total of 100 parts by weight of components (A) and (B).
A thermoplastic resin composition characterized in that the amount is less than 0.05 part by weight. The composition according to the present invention has excellent stability in a molten state, and can provide a thermoplastic resin composition for molding that has excellent processability, physical properties, mechanical properties, and the like. In particular, the ability to prevent strand breakage during extrusion molding when chipping the composition and the excellent transparency of the resulting molded products are major advantages in industrialization. Although the effect of the carboxylic acid or its anhydride used in the present invention has not been fully elucidated, it is thought that it suppresses the decomposition of the polyester resin in the molten state. However, it is completely surprising that a very small amount of addition can produce a remarkable effect. The polyester resin used in the present invention is a polyester resin mainly containing ethylene terephthalate repeating units, and includes not only polyethylene terephthalate but also acid components such as isophthalic acid, p-oxybenzoic acid, diphenylmethanedicarboxylic acid, adipic acid, Examples include ethylene terephthalate polyester resins copolymerized with sebacic acid, naphthalene dicarboxylic acid, etc., or propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, bisphenol A, etc. as a glycol component. Specific examples of copolymerized polyesters include polyethylene terephthalate isophthalate, polyethylene terephthalate adipate, polyethylene terephthalate sebacate,
Examples include polyethylene terephthalate and betylene terephthalate. It may also be a copolymer of trifunctional or higher functional ester-forming components within a range that does not impair moldability. However, polyester resins containing ethylene terephthalate repeating units preferably have a content of 70 mol% or more, and particularly preferably 85 mol% or more. Alternatively, it may be a mixture of a plurality of polyester resins, the main component of which is ethylene terephthalate, by blending polyethylene terephthalate with another polyester. The polyester resin usually has an intrinsic viscosity of 0.4 or more when measured at 30°C in phenol/tetrachloroethane (6/4 weight ratio).
Further, it is particularly preferably 0.5 or more, and the melting point is preferably 200°C or more, particularly 240°C or more.
Further, the carboxyl group content of the polyester resin is usually 40 equivalents/ton or less, particularly preferably
30 equivalents/ton or less. In addition, the polycarbonate resin used in the present invention is a 4,4'-dioxydiarylalkane-based polycarbonate resin, particularly 4,4'-dioxydiphenyl-2,2-propane (commonly known as bisphenol A). Polycarbonate is particularly preferred. Although the polycarbonate resin can be produced by any method, it is preferably produced by the phosgene method or the transesterification method. For example, 4,4'-dioxydiphenyl-2,
2-propane polycarbonate resin is 4,4'-
The phosgene method uses dioxydiphenyl-2,2-propane as a dioxy compound and blows phosgene into it in the presence of an aqueous caustic alkali solution and a solvent, or 4,4'-dioxydiphenyl-
It is produced by a transesterification method in which 2,2-propane and diester carbonate are transesterified in the presence of a catalyst. Note that the molecular weight of the polycarbonate resin is usually preferably about 15,000 or more. The mixing ratio of the above polyester resin and polycarbonate resin is 30 to 95% by weight of polyester resin,
The proportion of polycarbonate resin is 70 to 5% by weight. Within this range, it is possible to obtain a molded article with superior thermal stability and dimensional stability as well as excellent mechanical properties compared to a polyester resin alone. If the polycarbonate resin content is less than 5% by weight, the molded product is likely to be thermally deformed and has the disadvantage of poor dimensional stability and impact resistance. On the other hand, if it exceeds 70% by weight, the excellent physical and mechanical properties of the polyester resin will be lost, and in particular, the decrease in rigidity will be significant. Particularly preferred blending ratios are 35 to 80% by weight of polyester resin and 20 to 65% by weight of polycarbonate resin. In the present invention, it is important to blend carboxylic acid or its anhydride in addition to the polyester resin and polycarbonate resin. The carboxylic acid or its anhydride used may be an aliphatic or aromatic carboxylic acid such as stearic acid or terephthalic acid, but acid anhydrides are usually preferred. Specific examples of acid anhydrides include caproic anhydride, lauric anhydride, stearic anhydride, benzoic anhydride, hexahydrophthalic anhydride,
Phthalic anhydride, 1,8-naphthalic anhydride, trimellitic anhydride, pyromellitic anhydride, cyclopentanetetracarboxylic anhydride, glycerol trimellitic anhydride, ethylene glycol bistrimellitic anhydride, benzophenonetetracarboxylic acid anhydride anhydrides, anhydrides of aliphatic or aromatic carboxylic acids such as n-dodecylsuccinic anhydride, maleic anhydride, fumaric anhydride; polycarboxylic anhydrides such as polysebacic anhydride and polyterephthalic anhydride; , an acid anhydride of trimellitic anhydride and an aliphatic monocarboxylic acid, and the like. Particularly preferred acid anhydrides are those of carboxylic acids having at least four carboxylic acid groups in the molecule, such as pyromellitic anhydride. The amount of the carboxylic acid or its anhydride is usually 0.005 to 100 parts by weight in total of the polyester resin and polycarbonate resin.
It is 0.05 part by weight. If the amount is less than 0.005 parts by weight, the effect of suppressing the decomposition of the polyester resin will be insufficient, the transparency of the molded article will be impaired, and the effect of improving impact resistance will not be obtained. On the other hand, if it exceeds 0.05 part by weight, strand breakage occurs frequently during chipping, and transparency also decreases. As a method for mixing the above resins and carboxylic acid or its anhydride, for example, carboxylic acid and/or its anhydride is added to the molten polyester resin before and after the completion of polyester polymerization, mixed uniformly, and then powdered. A method of adding and melt-mixing polycarbonate resin in the form of pellets or melt, or mixing polyester resin and polycarbonate resin in powder or pellet form, adding carboxylic acid and/or acid anhydride to this, and then melting. The method of mixing is appropriate, but
It is not limited to these. No matter which mixing method is used, the temperature at which the polyester resin and the carboxylic acid and/or acid anhydride come into contact is usually 270 to 290°C, preferably 275°C.
~285℃ range. In addition, the melt-kneading time of polyester resin and polycarbonate resin is usually 1
20 minutes, preferably 2 to 10 minutes, and it is preferably immediately extruded from a melt kneader and molded into pellets, or sent directly from the kneader to an injection molding machine or an extrusion molding machine. In addition, the composition of the present invention may further include various fillers as necessary, such as metal powder, diatomaceous earth, calcium carbonate, kaolin, wollastonite, talc, clay, mica, glass powder, hollow silica, foamed silica, Glass beads, carbon black, powder or granular fillers such as wood powder, glass fiber, carbon fiber,
Fibrous reinforcements such as aramid fibers, whiskers, metal carbide fibers, stabilizers such as heat stabilizers and light stabilizers, colorants, flame retardants, crystallization nucleating agents, lubricants,
Mold release agents, polyfunctional crosslinking agents, rubbery reinforcing agents, other thermoplastic resins, etc. can also be added. The present invention will be explained below with reference to Examples, and all parts in the Examples mean parts by weight. Example 1 Polyethylene terephthalate (η = 0.6, carboxyl group content 25 equivalents/ton) (hereinafter abbreviated as PET) and polycarbonate resin (Mitsubishi Gas Chemical Co., Ltd. bisphenol A polycarbonate molecular weight 24000)
(hereinafter abbreviated as PC) at 130℃ and 2mmHg.
It was dried under reduced pressure for 19 hours. PET60 dried in this way
Pyromellitic anhydride (Hani Chemical Co., Ltd., Extra Pure Reagent) was added to 1 part and 40 parts of PC in the proportions shown in Table 1, and the mixture was thoroughly mixed. Thereafter, the mixture was melt-kneaded in an extruder (VSK-40) manufactured by Chuo Kikai Seisakusho using a Dalmage screw at a cylinder temperature of 280°C and an average residence time of about 2 minutes to form a monofilament with a diameter of 3 mm. It was extruded into a shape. The shape of the strand was good, and after quenching in water, it was cut to obtain pellets. After drying the pellets thus obtained at 130°C under a reduced pressure of 2 mmHg for 15 hours, the mold temperature was set to 30°C using a Nissei Jushi Kogyo injection molding machine (FS-75).
Tensile test specimens for ASTM D-638 (1/8 inch thick) were molded. The transparency and haze value of the obtained test piece were measured using HAZEMETER-S manufactured by Toyo Seiki Seisakusho in accordance with JIS K-6714-1977, and the results shown in Table 1 were obtained. In addition, as comparative examples, PET single molded products and
Comparative example dates for a binary molded product of PET and PC and a case where a large amount of pyromethic anhydride is blended are also shown.
If a strand could not be obtained at that time, the lump was crushed and used for molding.

[Table] As a result, the composition according to the present invention had good operability, and a molded article with excellent transparency, which had a transparency of 70% or more and a haze value of 70% or less, was obtained. Example 2 Melt extrusion and injection molding were carried out under the same conditions as in Example 1 except that the molecular weight of PC was changed and the amount of pyromellitic anhydride added was 0.03 PHR, and the impact resistance, transparency, Heat Distortion Temperature (ASTM
D648, load 4.6Kg/cm ² ) was measured, and the results are shown in Table 2.

[Table] As a result, the composition according to the present invention exhibited excellent impact resistance and heat distortion temperature. Example 3 Example 1 except for changing the composition ratio of PET and PC
Melt extrusion and injection molding were carried out under the same conditions as above, and the properties of the obtained molded products were evaluated. The results are shown in Table 3.

[Table] The composition according to the present invention had good operability and gave molded articles with excellent balance of physical properties such as impact resistance, heat distortion temperature, and tensile modulus. If the amount of PC is too small, the impact resistance and heat distortion temperature will be insufficient, and if it is too large, the rigidity will be reduced. Example 4 60/40 weight ratio of PET and PC used in Example 1
0.03 part of pyromellitic anhydride was added to 100 parts, and a flat plate of 3 mm thickness, 100 mm length, and 100 mm width was injection molded using a film gate in the same manner as in Example 1. Also
A flat plate was formed using PET alone in the same manner. A falling ball impact test was conducted on the obtained flat plate at 23°C, and the results shown in Table 4 were obtained.

[Table] Falling ball impact strength test method A sample was placed on a fixed plate with a square shape of 80 mm on a side and a hole 35.5 mm deep, and a 3 mm thick rubber plate with holes of the same shape as the fixed plate and a steel plate. I fixed the whole thing with scissors and 4 bolts. On the other hand, a ball support guide in which a ball of a predetermined weight was placed on a ball support pin whose height could be changed at 5 cm intervals was placed on the sample. When the ball support pin is pulled out, the ball falls and impacts the center of the sample. Change the height at 5cm intervals, such as 5cm, 10cm...
The height at which a crack appeared for the first time in the sample after repeatedly falling the ball was defined as the falling ball impact height. Then, the falling ball impact strength was calculated using the following formula. Falling ball impact strength (Kg·cm) = Weight of ball (Kg) x Falling ball impact height (cm) The measurement was performed 5 times and the average value was expressed. Example 5 The two types of flat plates prepared in Example 4 were subjected to boiling water treatment at 100°C to measure changes in transparency over time, and the results are shown in Table 5.

[Table] Regarding the transparency of the product of the present invention, even when subjected to boiling water treatment at 100°C, the translucency is maintained for a long time, and unlike PET, it does not suddenly devitrify. Example 6 Using PC with a molecular weight of 22,000, melt extrusion and injection molding were carried out under the same conditions as in Example 2 except that 0.03 PHR of pyromellitic anhydride was added, and ASTM D-
A tensile test piece for 638 (1/8 inch thick) was obtained. The obtained tensile test piece was placed in an oven at 100℃ for 2
Measure the dimensional change rate in the longitudinal direction after time heat treatment,
The results shown in Table 6 were obtained. In addition, as a comparative example
Specimens of PET alone were also molded and tested for comparison.

[Table] It is clear that the molded articles obtained from the compositions of the present invention have extremely small post-shrinkage, and therefore are difficult to deform (warp) even when used at around 100°C.

Claims (1)

[Claims] 1. Polyester resin (A) containing ethylene terephthalate repeating units as a main component and polycarbonate resin
A thermoplastic resin composition comprising (B) and a carboxylic acid or its anhydride (C) as essential components, wherein the ratio of component (A) to component (B) is (A):(B) = 30 to A thermoplastic resin having a weight ratio of 95:70 to 5 and containing component (C) in an amount of 0.005 part by weight or more and less than 0.05 part by weight based on a total of 100 parts by weight of components (A) and (B). Composition. 2. The thermoplastic resin composition according to claim 1, wherein the carboxylic acid or its anhydride is a polycarboxylic anhydride.