JPH02248460A - Highly crystalline polyester resin composition - Google Patents

Abstract

PURPOSE:To improve the mechanical and thermal properties, chemical resistance, and moldability by compounding a polyester resin, a specific polyalkylene glycol of which both terminals are blocked, and a crystallization accelerator. CONSTITUTION:100 pts.wt. polyester resin having ethylene terephthalate as the main repeating unit, obtd. by (trans)estrifying a dicarboxylic acid (deriv.) component of which at least 90mol% is terephthalic acid with a glycol component of which at least 90mol% is ethylene glycol and by polycondensing the resulting product, is compounded with 0.5-8 pts.wt. polyalkylene glycol having a weight-average MW of 500-4000, of which both terminals are blocked by substituting the hydrogen atoms of both terminal hydroxyl groups each with a group selected from the consisting of alkyl, aryl, and aralkyl groups, and 0.1-5 pts.wt. crystallization accelerator (e.g. sodium laurate).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a highly crystalline polyester resin composition having excellent mechanical properties, thermal properties, chemical resistance and moldability.

[Prior art and problems to be solved by the invention] Due to its excellent heat resistance, mechanical strength, and chemical resistance, polyethylene terephthalate is used in a wide range of fields such as fibers, films, and molded products such as beverage bottles. It is used.

However, the excellent properties of these molded products largely depend on the crystallinity of polyethylene terephthalate.

The crystallization rate of polyethylene terephthalate is nylon,
Compared to other crystalline polymers such as polyacetal, it is quite small (polyethylene terephthalate is molded under molding conditions suitable for practical use in molded products, specifically mold temperatures of 70°C or higher and a short molding cycle of about 30 seconds). In other words, when molding is performed at a high mold temperature, the resulting molded product lacks mechanical strength when taken out of the mold, resulting in poor dimensional stability; When molded with polyethylene terephthalate, although the moldability is good, the crystallinity of the resin constituting the resulting molded product is insufficient, making it impossible to produce a molded product that exhibits the excellent properties inherent to polyethylene terephthalate.

Therefore, various methods have been proposed to improve the crystallization rate of polyethylene terephthalate. These methods can be roughly classified into the following two methods. One of these is to shorten the supercooling time that occurs during the crystallization process from the molten state during normal melt molding of polyethylene terephthalate (in order to promote the generation of crystal nuclei, polyethylene terephthalate is injected with talc, silica, kaolin, aluminium, etc.). A method of adding inorganic additives such as
707, Special Publication No. 47-27142, etc.),
A method of adding a salt of a copolymer of α-olefin and an unsaturated carboxylic acid (Japanese Patent Publication No. 45-26225, etc.) or a method of adding an organic carboxylate such as sodium benzoate (Japanese Patent Publication No. 46-29977) Publication No., Japanese Patent Application Publication No. 1983
-158452, etc.).

Another method is to add polyoxyalkylene, polyalkylene sebacate, or polyalkylene with a low glass transition point to polyethylene terephthalate in order to improve the mobility of polyethylene terephthalate polymer chains at temperatures lower than the crystallization temperature of polyester. This is a method of adding a homopolymer such as adipate or a block copolymer thereof (Japanese Patent Publication No. 57-87543, Japanese Patent Publication No. 57-14)
5145, JP-A-57-179239, JP-A-58-21097, etc.).

The mechanism by which these additives promote crystal nucleation in polyethylene terephthalate is not known in detail, but nucleating agents with basic compounds such as carboxylates partially reduce the molecular weight of polyethylene terephthalate. Molded products obtained from products containing such additives will inevitably have disadvantages in terms of physical properties.Also, polyalkylene sebacate, polyalkylene In polyester resin systems containing adipate, etc., these additives can be expected to have a plasticizing effect that helps the mobility of the polymer chains of polyethylene terephthalate at low temperatures, but they do Since it has little effect on the generation of crystal nuclei, it is necessary to use it in combination with a nucleating agent in order to improve crystal development in these resin systems.

Furthermore, when polyethylene terephthalate is added with the above-mentioned additives, there are problems such as coloring and gas generation during molding, which limits the molding temperature and the amount of these additives.

Furthermore, in our previously filed patent application No. 182,685/1985, we copolymerized polyethylene terephthalate with a polyalkylene glycol of a specific molecular weight and a polyalkylene glycol blocked at one end, resulting in high crystallinity suitable for molding. However, the modified polyester obtained by this method still does not have sufficient crystallinity compared to polybutylene terephthalate.

[Means for Solving the Problems] In view of the current situation, the present inventors have conducted intensive research and found that by blending polyethylene terephthalate with polyalkylene glycol at both ends and a crystallization accelerator, the moldability can be improved. The inventors have discovered that a highly crystalline polyester resin composition with excellent properties can be obtained, and have arrived at the present invention.

That is, the present invention is based on (A) 100 parts by weight of polyester having ethylene terephthalate as a main repeating unit, and (B) the weight of hydrogen in both terminal hydroxyl groups substituted with an alkyl group, an aryl group, or an aralkyl group. A highly crystalline polyester resin composition comprising 0.5 to 8 parts by weight of a double end-capped polyalkylene glycol having an average molecular weight of 500 to 4000 and 0.1 to 5 parts by weight of (C) a crystallization accelerator. be.

The polyester (A) having ethylene terephthalate as the main repeating unit used in the present invention is
It is a polymer obtained by subjecting a dicarboxylic acid or its derivative component consisting of terephthalic acid in mol% and an ethylene glycol component of at least 90 mol% to an esterification reaction or transesterification reaction, and then a polycondensation reaction. Examples of dicarboxylic acid derivatives include dialkyl esters and diaryl esters of terephthalic acid. Examples of dicarboxylic acids that can be used in combination with the terephthalic acid component in an amount of 10 mol% or less include phthalic acid, isophthalic acid, adipic acid, sebacic acid, and naphthalene-1,4- or -2,6 dicarboxylic acid. , diphenyl ether-4,4-dicarboxylic acid, and the like.

Also, as a glycol component, 1% of ethylene glycol
Glycols that can be used together in a range of 0 mol% or less include:
Propylene glycol, butylene glycol, neopentyl glycol, cyclohexane dimetatool, 2,2
-Glycols such as -bis(4-hydroxyphenyl)propane and the like can be mentioned. As other components used in obtaining the polyester of Ikemizu's invention, oxyacids such as p-hydroxybenzoic acid and p-hydroxyethoxybenzoic acid can also be used in combination.

Specific examples of the double-terminated polyalkylene glycol (B) used in the present invention include polyethylene glycol, polypropylene glycol, polytrimethylene glycol,
Examples include polytetramethylene glycol and random or block copolymers of polyethylene glycol and polytetramethylene glycol in which the hydrogens of both terminal hydroxyl groups are substituted with groups selected from alkyl groups, aryl groups, and aralkyl groups. . Examples of the alkyl group, aryl group, and aralkyl group include methyl group, ethyl group, phenyl group, benzyl group, and methylphenyl group. Among these, it is most preferable that the polyalkylene glycol is polyethylene glycol in which the hydrogens of both terminal hydroxyl groups are substituted with methyl groups.

Since such polyalkylene glycol end-blocked at both ends has no reactivity, when it is blended with polyester, it is uniformly dispersed in the polyester. Since polyalkylene glycol has higher mobility of molecular chains than polyester, it is presumed that the so-called plasticizing effect improves the mobility of polyester molecular chains and exerts a crystallization promoting effect.

On the other hand, the double-end-blocked polyalkylene glycol of the present invention is not incorporated into the main chain of the polyester and only acts as a plasticizer, so compared to molded products obtained from polyester resins copolymerized with conventional polyalkylene glycols. Therefore, molded articles obtained from the polyester resin composition of the present invention may suffer from a decrease in mechanical strength, discoloration, and a decrease in thermal stability.

The weight average molecular weight of these both end-capped polyalkylene glycols is preferably in the range of 500 to 4,000. Although compounds with a weight average molecular weight of less than 500 are highly effective as plasticizers, it is necessary to increase the amount of the compound added in the polyester in order to express the crystallization promoting effect, and polyester blended with the polyethylene glycol The mechanical strength of the molded product obtained from the resin composition decreases.

Further, polyalkylene glycols having a weight average molecular weight of more than 4,000 are not preferred because their dispersibility in polyester decreases and the crystallization promoting effect decreases.

The amount of the polyalkylene glycol endblocked at both ends is preferably in the range of 0.5 to 8 parts by weight, more preferably in the range of 0.5 to 8 parts by weight, based on 100 parts by weight of the polyester.

If the amount is less than 0.5 parts by weight, the effect of promoting crystallization is small (unpreferable). If the amount is more than 8 parts by weight, the mechanical properties of the resulting molded product will be extremely reduced.

It is preferable that the polyalkylene glycol endblocked at both ends is incorporated into the polyester while the polyester polycondensation reaction is being carried out.

Adding a double-terminated polyalkylene glycol during the polycondensation reaction under vacuum minimizes the denaturation of the compound without being affected by oxygen, thereby minimizing unnecessary molecular weight reduction of the polyester. Further, even if the degree of polycondensation of the polyester in the pot decreases due to the addition of the compound, by continuing the polycondensation reaction, it is possible to obtain a polyester resin with a predetermined degree of polycondensation. .

Examples of the crystallization promoter used in the present invention include metal salts of Group 1a or Group 1[a of the periodic table of organic carboxylic acids, benzoic acid esters or esters of benzoic acid derivatives, fatty acid esters, ionic co-organic acids, etc. Examples include metal salts of polymers, inorganic particles, polyoxyethylene derivatives, epoxy compounds, sorbitan derivatives, etc. Specifically, sodium laurate,
Potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium stearate, potassium stearate, calcium stearate, sodium octacosanoate, calcium octacosanoate, sodium benzoate, potassium benzoate,
Calcium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, ethylene glycol monobenzoate, ethylene glycol dibenzoate, propylene glycol monobenzoate, propylene glycol dibenzoate, neopentyl glycol monobenzoate, diethylene glycol dibenzoate, triethylene glycol dibenzoate Benzoate, ethylene glycol propylene glycol dibenzoate,
Ethylene-sodium acrylate copolymer, ethylene-
Examples include sodium methacrylate copolymer, talc, titanium oxide, zinc oxide, and the like.

The blending amount of these crystal accelerators is preferably 0.1 to 5 parts by weight, more preferably 0.5 parts by weight, based on 100 parts by weight of polyester.
~3 parts by weight is preferred. The amount of crystallization accelerator is 0.1
If the amount of the polyester resin composition is less than 5 parts by weight, the effect of promoting crystallization will not be sufficient, and a molded article obtained from a polyester resin composition containing more than 5 parts by weight will easily become brittle.

The timing of adding the crystallization promoter is not particularly limited. Therefore, the crystallization accelerator may be added during the polymerization reaction of the polyester, or may be added during the extrusion process with the polyester pellet.

Depending on the purpose, the polyester copolymer of the present invention can be used with fibrous fillers such as glass fiber, alumina fiber, carbon fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, and metal fiber, talc, kaolin, mica, clay, and wollastenite. , silicates such as sericite, bentonite, asbestos, alumina silicate, metal oxides such as alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, carbonates such as calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, sulfuric acid. Particulate fillers such as sulfates such as barium, glass peas, boron nitride, and silicon carbide, lubricants and mold release agents such as silica and stearate, ultraviolet absorbers, colorants including pigments such as carbon black, and halogens. Known additives such as flame retardants such as compounds and phosphorus compounds, flame retardant aids, antioxidants, antistatic agents, and heat stabilizers may be optionally added.

In addition, small amounts of other thermoplastic resins (e.g., polyethylene, polypropylene, olefin resins such as ethylene copolymers, acrylic resins, fluororesins, polyamides, polyacetals, polycarbonates, polysulfones, polyphenylene oxides, polyester elastomers, ABS
resins, graft copolymers such as MBS resins) and thermosetting resins (e.g. phenolic resins, melamine resins, polyester resins, silicone resins, epoxy resins, etc.)
can be blended. Moreover, since the polyester resin composition of the present invention can be made into a highly crystalline molded article, it can be applied to all fields requiring heat resistance, impact resistance, mechanical strength, chemical resistance, etc. The polyester resin composition of the present invention can be easily obtained into a molded body by a molding method such as injection molding or extrusion molding, or can be obtained by obtaining fibers by known spinning and processing techniques, or by a tenter method or an inflation method. It is also possible to obtain a film-like product, and the method of forming it is not particularly limited. Products obtained by these molding methods are
All exhibit excellent properties derived from high crystallinity.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples. In addition,
The molding and evaluation of the test pieces in the examples were carried out in the following manner.

(1) Molding of test piece The resin composition to be evaluated is heated to 140°C under vacuum,
Drying was carried out for 8 hours. Next, this was put into the hopper of a 45 mmφ screw injection molding machine, melted and kneaded at a cylinder temperature of 260°C to 280°C, and molded into 8 oz A37M No. 1 dumbbells and 1/2 inch by a mold set at 80°C.
Four inch wide Izot specimens were molded. The molding cycle at this time was 30 seconds.

(2) Evaluation of crystallization rate The crystallization rate was measured using a differential calorimeter using a sample that had been previously dried at 140°C for 8 hours, melted, and rapidly cooled, and heated at a heating rate of 10°C in a nitrogen stream. /min, 280℃
The temperature was maintained for 3 minutes and the temperature was lowered at a rate of 10° C./min.

was measured. The higher Tmp is, the better the heat resistance is (Tc-
-Tc''), the higher the crystallization rate.

(3) Evaluation of mechanical strength Regarding the dumbbell test piece obtained by the method of (1), ASTM
A tensile test was conducted according to D-638.

(4) Evaluation of heat resistance The heat distortion temperature (HDT) of the A37M1 dumbbell was measured according to ASTM D-648, and was used as an index of heat resistance.

(5) Evaluation of moldability and molded product surface ASTM No. 1 dumbbells were visually judged.

[Moldability] ×: Molding is extremely difficult in a 30 second cycle due to poor mold release and poor shape retention.

Δ: Trial molding is possible, but not practically suitable for production.

O: Good molding operation is possible.

[Surface of molded product] ×: The surface has no gloss, and sink marks, flow marks, avatars, etc. are scattered.

Δ: There are no sink marks, flow marks, avatars, etc., but the surface is not glossy.

○: There are no defective spots on the back surface, and the film has good gloss.

Examples 1 to 5 and Comparative Examples 1 to 7 200 parts by weight of ethylene glycol and 100 parts by weight of terephthalic acid
Charge part by weight into a reaction vessel, pressurize the inside of the vessel, and bring the temperature inside the vessel to 24.
The esterification reaction was carried out at 0°C. When no more water is distilled out and the top temperature of the water distillation column starts to rise, 5bio is added as a polymerization catalyst.

was added to the product in the kettle in an amount of soppm, and while the temperature in the kettle was raised to 280°C, the pressure inside the kettle was reduced to perform a polycondensation reaction. Intrinsic viscosity of the reactant in the pot [η] (dissolved in an equal weight mixture of phenol and tetrachloroethane at 25°C)
After increasing the degree of polymerization until 0.60 (measured in
Polyethylene glycol dimethyl ether and talc (Fuji Talc Co., Ltd. LMS-100) were added in amounts shown in Table 1. After that, the polycondensation reaction is further advanced, [η]
The obtained polyester resin composition was taken out of the pot when the value of 0.85 was reached.

The polyester resin composition thus obtained was prepared in the above (1).
Table 1 shows the results of molding and evaluation using the method described above. on the other hand,
The molded products were obtained and evaluated in exactly the same manner as in Examples 1 to 5, except that the amounts of polyethylene glycol dimethyl ether and talc were outside the range of the present invention (Comparative Examples 1 to 7).
Also listed in the table.

In Examples 1 to 5 according to the present invention, molded products having good appearance were successfully molded. The mechanical properties of these molded products are based on polyethylene terephthalate (
Compared to Comparative Example 1), it has high strength and low elongation, and a decrease in Izot impact strength is observed, but this is due to a significant increase in crystallinity and is at a level that poses no problem in practice.

Furthermore, in Examples 1 to 5, the DSC results show that they all exhibit extremely high crystallinity, and it is found that they have extremely excellent heat resistance (HDT) due to this.

On the other hand, when the additive is only polyethylene glycol dimethyl ether or only talc, the moldability is insufficient.
Heat resistance (HDT) is not sufficiently developed. Moreover, in Comparative Example 4.5, in which the weight average molecular weight of polyethylene glycol dimethyl ether is outside the range of the present invention, good molding cannot be performed, and the mechanical properties and heat resistance are also insufficient.

Comparative Example 6, in which the amount of polyethylene glycol dimethyl ether added exceeds the range of the present invention, had poor moldability, and Comparative Example 7, in which the amount of talc added exceeded the range of the present invention, had good moldability and heat resistance. However, the mechanical properties of the material are extremely deteriorated.

[Effects of the Invention] Since the polyester resin composition obtained by the present invention exhibits unprecedented high crystallinity, the field of application of the resin has been expanded, and particularly in the molding field, the moldability and heat resistance of molded products have been significantly improved. Improve.

Claims (1)

[Claims] (A) Weight average molecular weight of 500 to 100 parts by weight of polyester having ethylene terephthalate as the main repeating unit, and (B) hydrogen of both terminal hydroxyl groups substituted with an alkyl group, an aryl group, or an aralkyl group. 40
00 both end-capped polyalkylene glycol from 0.5 to
A highly crystalline polyester resin composition comprising 8 parts by weight and 0.1 to 5 parts by weight of (C) a crystallization accelerator.