JPS627949B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a crystalline polyester composition that has a high elastic modulus and excellent hot water resistance. Polyethylene terephthalate and poly-1/4-
Crystalline polyesters such as butylene terephthalate have excellent mechanical properties and hot water resistance, so they are widely used in films, fibers, and various molded products. Molded products are desired;
For this purpose, crystalline polyesters with even higher strength and higher elastic modulus are required. Furthermore, when crystalline polyester is applied to the field of molded products such as bottles and food containers, there is a strong demand for hot water resistance that can withstand hot water injection and hot water sterilization. Conventional methods for improving the above-mentioned patent requirements for crystalline polyester include copolymerizing crystalline polyester with a specific third component and blending crystalline polyester with another polymer having a high glass transition point. However, in the former copolymerization method, it is necessary to increase the copolymerization amount of the third component in order to obtain a sufficiently high glass transition point.
The crystallinity of the polyester itself is lost, and in the latter blending method, the compatibility of the polymers is poor, so uniform mixing is often not achieved, and even if uniform mixing is possible, the crystallinity of the polyester itself is significantly reduced. . On the other hand, methods of adding various organic compounds to crystalline polyester to improve its properties (for example, Japanese Patent Publication No. 47-48894, Japanese Patent Publication No. 52-973, Japanese Patent Application Laid-Open No. 47-23446, 53-101046, etc.), but in these methods, the organic compound added acts as a crystallization promoter and can lower the elevated crystallization temperature (Tcc). However, the elastic modulus and hot water resistance of the polyester itself are not improved. Therefore, the present inventors conducted extensive studies to effectively improve the elastic modulus and hot water resistance of crystalline polyester without impairing its crystallinity, and as a result, it was discovered that the above objectives can be achieved by adding an aromatic ester that can take a liquid crystal state. This discovery led to the present invention. That is, the present invention provides a crystalline polyester which is made by blending 0.1 to 20 parts by weight of a liquid crystalline aromatic ester with a nematic melting point (temperature at which phase transition from solid state to nematic liquid crystal occurs) of 120°C or higher to 100 parts by weight of crystalline polyester. A polyester composition is provided. Liquid crystalline aromatic esters can be blended extremely uniformly into crystalline polyesters, and although they increase the elevated temperature crystallization temperature (Tcc) of polyesters and reduce the crystallization rate to some extent, surprisingly, the crystallization rate of the polyester itself is lowered. It acts effectively on improving the elastic modulus and hot water resistance without any influence on the temperature. The crystalline polyesters used in the present invention include polyethylene terephthalate, poly-1,4-butylene terephthalate, polyethylene 2,6-naphthalate, polycyclohexanedimethanol terephthalate, poly-1,4-butylene diphenyl-
Linear crystalline polyesters such as 4,4'-dicarboxylate, polyethyleneoxybenzoate, poly-1,3-propylene terephthalate, poly-1,6-hexylene terephthalate, polyethylene terephthalate, poly-1,4 -butylene terephthalate and polyethylene-2,6-naphthalate are preferably used. These crystalline polyesters can be copolymerized with other dicarboxylic acids or glycols, usually within 30 mol%, as long as their crystallinity is not significantly disturbed. It may also be a block ester obtained by copolymerizing polyethylene glycol or polytetramethylene glycol in an amount of 50% by weight or less. The liquid crystalline aromatic ester used in the present invention is, for example, MJSDewar, J.Org.Chem., 35, 2711.
(1970) general formula as stated in or (R: alkyl, alkoxy, ester group, etc.)
It is a compound represented by , and exhibits a nematic liquid crystal structure. Other examples include R. Steinstra¨sser Angew.Chem.
The general formula as stated in , internat.Edit, 11 , 633 (1972) Compounds represented by (R: alkyl group, alkoxyl group, R': alkyl group, alkoxyl group, ester group) can also be used. These liquid crystalline aromatic esters must have a nematic melting point of 120°C or higher, especially 140°C or higher, and a liquefaction melting point of 150 to 300°C or higher.
If the nematic melting point is 120° C. or lower, the effect of improving the elasticity of the crystalline polyester is small, and rather it acts as a plasticizer, which is not preferable. Specific examples of particularly preferred liquid crystalline aromatic esters include the following. The amount of liquid crystalline aromatic ester added is 0.1 to 20 parts by weight, particularly, per 100 parts by weight of crystalline polyester.
Selected from the range of 0.5 to 7 parts by weight, and the amount added is 0.1
If it is less than 20 parts by weight, the improvement effect will be small, and if it is more than 20 parts by weight, the properties specific to crystalline polyester will be lost, which is not preferable. The polyester composition of the present invention is generally produced by a known method. For example, a method of melt-mixing crystalline polyester and a liquid crystalline aromatic ester in an extruder or kneader, a method of fixing the liquid crystalline aromatic ester to crystalline polyester particles, a method of adding the liquid crystalline aromatic ester to a polyester polymerization pot immediately after polymerization, etc. Examples include a method of directly adding and mixing a group ester. The composition of the invention contains 100% crystalline polyester
Other thermoplastic resins such as polyethylene, polypropylene, modified polyolefin, polystyrene, polycarbonate, polyamide, polyurethane, etc. may be blended in an amount of 30 parts by weight or less based on the weight part. The polyester composition of the present invention contains 5 to 50 reinforcing materials such as glass fiber, carbon fiber, asbestos, wollastenite, and whiskers in order to improve heat distortion temperature and stiffness within a range that does not impair its practicality.
It can be added in a range of % by weight. A crystallization accelerator can be added to the composition of the present invention, if necessary. As a crystallization accelerator,
Inorganic solids such as talc, barium sulfate, silicon oxide, and alumina, which are generally referred to as nucleating agents, higher fatty acid salts such as sodium stearate, barium stearate, and sodium palmitate, and aromatic carboxylates such as sodium benzoate and dilithium terephthalate. , a copolymer of α-olefin and an α/β-unsaturated carboxylic acid salt, and a high melting point polyester powder are effective. The amount of these crystallization accelerators added is 0.1 to 100 parts by weight of polyester.
Selected from a range of 10 parts by weight. A flame retardant can also be added to the composition of the present invention to impart flame retardancy. Examples of flame retardants include aromatic halogen compounds such as decabromodiphenyl ether, tetrabromobisphenol A, carbonate oligomers of tetrabromobisphenol A, polycarbonates, glycidyl ether of tetrabromobisphenol A, melamine, and melamine cyanurate. preferable. When antimony oxide is used in combination with a halide, the flame retardant effect is further improved. Depending on the purpose, stabilizers (phosphorus compounds, epoxy compounds, etc.), mold release agents (wax, wax, esters, etc.), antistatic agents, etc. can be added to the composition of the present invention. The composition of the present invention is made into molded products by extrusion molding, injection molding, blow molding, etc., and the molded products obtained have excellent mechanical properties represented by elastic modulus and hot water resistance, and can be used as films, tapes, etc. , useful as bottles and tableware containers, etc. The effects of the present invention will be explained below with reference to Examples. In the Examples, the breaking strength, breaking elongation, and elastic modulus were measured in accordance with the method of ASTM D882. Furthermore, the relative viscosity η _r of the polyester mentioned in the examples is based on the value measured at 25° C. of a 0.5% by weight polymer solution using orthochlorophenol as a solvent. Example 1 Synthesis A of liquid crystalline aromatic esters A to D: Bis(p-methoxyphenyl) terephthalate
ester 25 g of hydroquinone monomethyl ether and 16 g of pyridine were dissolved in 300 c.c. of chloroform, and 21 g of terephthaloyl chloride dissolved in 100 c.c. of chloroform was added dropwise to this solution. Dripping was controlled while cooling with water so that the temperature was 50°C. After dripping for 2 hours, the bath was changed to a hot water bath and refluxed for 2 hours to complete the reaction. The precipitate was collected, washed with methanol, and recrystallized from dioxane. Nematic melting point 200-205℃ Yield 30g B: Hydroquinone bis-(P-methoxybenzoic acid) ester 30 g of p-methoxybenzoic acid and 25 g of oxal chloride were reacted in 200 ml of benzene under reflux to synthesize p-methoxybenzoic acid chloride. Separately, dissolve 8 g of hydroquinone in 100 ml of water containing 7 g of caustic soda, and add the above P
- A benzene solution of methoxybenzoic acid chloride was added dropwise. After dropping over 1 hour, the mixture was heated under reflux for 2 hours to complete the reaction. The benzene solution was separated, the solvent was evaporated, and the precipitate was collected and recrystallized from dioxane. Nematic melting point 210−
215℃, yield 28g C: Terephthalic acid bis(P-heptoxyphenyl) ester According to method A, hydroquinone mono
-Synthesized from heptyl ether and terephthaloyl chloride. Nematic melting point 150-153°C D: Hydroquinone bis-(P-octylphenylbenzoic acid) ester (Comparative Example 1) It was synthesized from P-octoxybenzoic acid chloride and hydroquinone according to method B.
Nematic melting point: 115-118°C Example 2 2 parts by weight each of the liquid crystalline aromatic esters A to D synthesized in Example 1 were added to 100 parts by weight of polyethylene terephthalate (hereinafter abbreviated as PET) chips with a relative viscosity of 1.65, Pellets were obtained by kneading at 285°C using an extruder with a screw of 30 mmφ. Table 1 shows the thermal properties of a portion of this pellet determined by the DSC method. For comparison, cases in which no liquid crystalline aromatic ester is used, cases in which low melting point liquid crystalline aromatic ester D is used, and cases in which benzophenone known as a nucleating agent for PET are used are also shown, but the composition of the present invention It is a surprising fact that even though they are uniformly compatible, they hardly lower the elevated crystallization temperature (Tcc), or even increase it in some cases. Tm: Melting point, Tc: Cooling crystallization temperature,
The temperature was measured at a rate of 20°C/min and a temperature drop at 20°C/min.

【table】

[Table] Example 3 0.1% by weight of silicon dioxide (thyroid) was externally added to each sample obtained in Example 2, and the samples were heated at 285°C using an extruder equipped with a T-die and a screw of 40 mmφ.
Extruded onto a casting drum at 50℃, thickness
A 500μ sheet was created. Using this sheet, the film was stretched 3.3 times in the MD direction at 90°C, then TD.
The film was stretched 3.3 times in the same direction and finally heat-treated at 210°C for 15 minutes. Table 2 shows the physical properties of the obtained film. Furthermore, in order to compare the stretchability, the maximum stretching ratio when uniaxially stretched in the MD direction is also shown in Table 2. It is clear that the composition of the present invention has excellent stretchability and provides a film with a high modulus of elasticity.

[Table] Example 4 0.5 parts by weight each of terephthalic acid bis(p-methoxyphenyl) ester (A) synthesized in Example 1 and terephthalic acid bis(p-caproxyphenyl) ester (D) for comparison was externally added to 100 parts by weight of PET chips with a relative viscosity of 1.60. Furthermore, for comparison, PET chips to which nothing was added were also used, and cold parisons of 2 mm thickness were molded for each using a famous SJ-35A injection molding machine. Molding conditions are cylinder temperature 295-290
℃, mold temperature 50℃, injection pressure (instruction) 17Kg/cm ² ,
The cycle was 8 seconds/10 seconds (boost 1 second). Next, a 500 c.c. small beer bottle was preheated to 120°C for 2 minutes using a Nippon Steel V-8 blow molding machine, and blow pressure was applied.
Blow molding was performed at 6.0Kg/cm ² . About the molded bottle Haze (transparency) of the body,
The hot water injectability (bottle shrinkage rate) and the tensile properties of the bottle body were measured. The results are shown in Table 3. It is clear that the composition of the present invention provides molded articles with excellent hot water resistance and strength.

【table】

Claims (1)

[Claims] 1. A crystalline polyester composition comprising 100 parts by weight of crystalline polyester and 0.1 to 20 parts by weight of a liquid crystalline aromatic ester having a nematic melting point of 120°C or higher.