JPS59531B2 - polyester resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyester resin composition having excellent moldability and physical properties. The present invention relates to novel polyester resin compositions which provide improved molded articles.

Polyethylene terephthalate has excellent heat resistance, chemical resistance, mechanical properties, electrical properties, etc., and is used in many industrial products as fibers and films. However, when it is intended to be used as an injection molded product for plastic purposes, it is known that there are major drawbacks in terms of molding and physical properties. That is, the drawbacks are poor moldability due to the low crystallization rate at low temperatures and brittleness due to the formation of large spherulites, which significantly limits its use as an injection molding material or an extrusion molding material. Traditionally, nucleating agents, especially talc, have been used to promote the crystallization of polyethylene terephthalate.
Incorporation of inorganic fillers such as clays is also known.

However, although the crystallization rate during high-temperature molding can be improved by adding an inorganic filler, it is difficult to shift the crystallization initiation temperature to a lower temperature, and even if 20% by weight or more of an inorganic filler is added, The crystallization initiation temperature decreases by at most about 10°C, and surface crystallization of the molded product in low-temperature mold molding of 100°C or less is completely insufficient. Also,
An attempt was also made to promote crystallization by using 0.05 to 3% by weight of an inorganic filler such as talc or clay together with 0.01 to 2% by weight of polyepoxide to polyethylene terephthalate, as disclosed in Japanese Patent Publication No. 47-2193. Official Gazette, Special Publication 1977
Although it is known from Publication No. 33256, etc., the effect of promoting crystallization is still insufficient, and it is impossible to obtain a molded product with excellent surface properties and excellent physical properties using a low temperature mold of 100°C or less. be. Furthermore, when a large amount of the polyepoxide described in this publication is blended, gelation occurs during kneading or molding, which impairs moldability. On the other hand, a method of improving the impact resistance of polyethylene terephthalate by blending glass fiber was also proposed in the Japanese Patent Publication No. 44-45.
It is known from Publication No. 7.

However, blending a large amount of glass fiber not only increases costs but also has drawbacks such as causing strength anisotropy in the molded product and warping deformation. Furthermore, a method of improving the impact resistance of polyethylene terephthalate by blending various rubber-like substances is also known from Japanese Patent Publication No. 46-5224, Japanese Patent Publication No. 46-5225, Japanese Patent Publication No. 46-5226, etc. Not only is the improvement in impact resistance insufficient due to poor compatibility between the rubbery substance and polyethylene terephthalate and poor adhesion between the two resins, but also the moldability and surface properties of the molded product are poor. It has its drawbacks. The present inventors have arrived at the present invention as a result of intensive research to develop a polyester resin composition that has excellent low-temperature crystallinity, moldability, and improved toughness.

That is, the present invention comprises (4) 60 to 98.5 parts by weight of polyethylene terephthalate or a copolyester containing 80 mol% or more of ethylene terephthalate repeating units, (B) a polyalkylene glycol compound having a molecular weight of 200 to 5000; .5 to 10 parts by weight, and 1 to 30 parts by weight of an olefinic elastomer having an ethylene component (C) of 30 to 95% by weight and having a glass transition point of 0° C. or lower. It is. The composition of the present invention can be molded even when molded in a low-temperature mold of 100°C or less because the polyalkylene glycol compound effectively shifts the crystallization initiation temperature to a lower temperature side and significantly increases the crystallization rate. It becomes possible to sufficiently promote crystallization up to the surface layer of the article, and the mold releasability and surface characteristics of the molded article can be significantly improved.

Furthermore, the molded product has excellent surface gloss, and even if it is a low-temperature molded product, it has excellent dimensional stability and shape stability at high temperatures. In addition, by using a specific olefin-based elastomer in combination with a polyalkylene glycol-based compound, the dispersibility of the olefin-based elastomer in polyester resin is improved, and the olefin-based elastomer forms a fine dispersed phase in the polyester resin. It has the characteristic of providing excellent toughness due to its excellent interfacial adhesion between the resin and the specific olefin-based elastic body. Furthermore, even in molding at high mold temperatures, the molding cycle time can be significantly reduced.
Furthermore, since the molded product always has a stable and reproducible surface gloss, the fact that the hue of the colored molded product is stable is also a great practical advantage. The polyester resin used in the present invention is polyethylene terephthalate or a copolymerized polyester resin containing at least 80 mol% or more, preferably 90 mol% or more of ethylene terephthalate repeating units. As the copolymerization component, acid components and/or glycol components can be widely used. For example, acid components include isophthalic acid, naphthalene dicarboxylic acid,
Diphenyl ether 4,4' monodicarboxylic acid, adipic acid, sebacic acid, etc. are exemplified, and glycol components include propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexanedimethanol, 2,2 bis( 4-hydroxyphenyl)propane 2,2-bis(4
-hydroxy-2,3,5,6tetrapromophenyl)
Examples include propane. Also, P-oxybenzoic acid, P
An oxyacid such as -hydroxyethoxybenzoic acid can also be used as a copolymerization component. Furthermore, a trifunctional component may be copolymerized in a small amount so as not to impair moldability. Polyester resin is prepared using a mixed solvent of phenol/tetrachloroethane (
6/4 weight ratio) The intrinsic viscosity determined by measuring the solution at 30°C is preferably 0.5 or more, more preferably 0.5
It is particularly preferable that it is 5 or more. In addition, polyalkylene glycol compounds used in the present invention include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide,
Propylene oxide random or block copolymer,
Polyalkylene glycols such as ethylene oxide/butylene oxide random or block copolymers, polyneopentyl glycol, polyhydric alcohol/alkylene oxide adducts, mono- or polyglycidyl ethers of these polyalkylene glycols, ethoxypolypropylene glycol monoglycidyl ethers Examples include glycidyl ethers of polyalkylene glycol derivatives such as phenoxypolyethylene glycol monoglycidyl ether, phenoxypolypropylene glycol monoglycidyl ether, and benzyloxypolyethylene glycol monoglycidyl ether. Molecular weight is 200
A value of 5,000 or more is used. If the molecular weight is too high, it becomes incompatible with polyester, loses its crystallization promoting effect, and deteriorates both moldability and physical properties. On the other hand, if the molecular weight is too low, there will be disadvantages such as a large viscosity difference with polyester during kneading and deterioration of kneading properties, a loss of crystallization promoting effect due to volatilization, and a decrease in toughness if low molecular weight compounds remain. Furthermore, if the molecular weight of a reactive polyalkylene glycol is too low, crosslinking will occur and the viscosity will increase, resulting in a disadvantage that moldability, weld strength, toughness, surface smoothness, etc. will be reduced. However, preferred are polyalkylene glycol glycidyl ethers having a polyoxyalkylene chain and an epoxy group, such as the above-mentioned glycidyl ether, particularly polyalkylene glycol polyglycidyl having an average of 1.2 or more epoxy groups in the molecule. Ether is moldable,
Particularly preferred from the viewpoint of low water absorption, toughness, etc. Also, the molecular weight is 20
0-3000 is preferable, and 300-1500 is particularly preferable. A polyalkylene glycol glycidyl ether may be produced by using a polyalkylene glycol and a polyepoxy compound in combination and reacting the two during kneading or molding. Furthermore, the olefinic elastomer containing 30 to 95% by weight of ethylene component and having a glass transition point of 0°C or lower, preferably -20°C or lower, used in the method of the present invention includes ethylene, propylene, butylene, isobutylene, and benzene. α-olefins such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl esters of monocarboxylic acids preferably having 8 or less carbon atoms such as vinyl benzoate, or saponified products thereof, ethyl acrylate, propyl acrylate, From acrylic esters or methacrylic esters of alcohols preferably having 8 or less carbon atoms, such as butyl acrylate, isopropyl acrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate, and unsaturated acids such as acrylic acid and methacrylic acid. Examples include copolymers comprising at least one selected ethylenically unsaturated monomer.

In addition, in order to further improve the dispersibility and interfacial adhesion to polyester resins, we use olefinic elastomers such as epoxy group-containing ethylenically unsaturated monomers such as glycidyl methacrylate, glycidyl acrylate, vinyl glycidyl ether, allyl glycidyl ether, and glycidyl itaconate. Epoxy-modification can be achieved by copolymerizing or graft polymerizing an olefin-based elastomer during body production, or carboxy-modification can be similarly achieved by graft-polymerizing acrylic acid, maleic anhydride, etc. onto an olefin-based elastomer. You can also do it. The blending ratio of each of the above components in the present invention is 60 to 98.5 parts by weight of the polyester resin, 1 to 30 parts by weight of the olefin elastomer, and 0.5 to 10 parts by weight of the polyalkylene glycol compound.

If the proportion of the polyolefin elastomer is less than the above, the improvement in toughness will be insufficient, while if the proportion exceeds the above, the excellent properties of the polyester resin will be impaired and the rigidity will decrease, making it unsuitable. Also, if the polyalkylene glycol compound is less than the above blending ratio, the temperature will exceed 100°C.
The appearance of the molded product at the following low mold temperatures is poor, while when the above-mentioned mixing ratio is exceeded, the heat resistance and rigidity decrease, making it unsuitable. The composition of the present invention may further contain a fibrous reinforcing agent and/or an inorganic filler depending on the intended use.

Heat resistance, rigidity, etc. can be improved by adding fibrous reinforcing agents and inorganic fillers. The longer the length of fibers such as glass fibers that are usually blended, the greater the reinforcing effect, but they have the disadvantage of causing strength anisotropy in the molded product and increasing the amount of warp deformation.
In order to solve these drawbacks, combinations of glass fibers with short fiber lengths have been considered, but this has the drawback of low reinforcing effects. However, the composition of the present invention exhibits superior toughness as shown by increased elongation, has good toughness even when blended with short fiber length glass fibers and inorganic fillers, and has good toughness when molded. It has the characteristic of reducing the warp deformability of the product. Of course, fibers with different lengths can be used together, and the fiber length can also be adjusted by cutting the fibers by selecting a kneader or setting the mixing conditions.
The blending of inorganic fillers also has the effect of promoting crystallization, especially when using polyoxyalkylene glycol compounds that do not have epoxy groups, which have somewhat inferior crystallization promoting effects as polyoxyalkylene glycol compounds. It is preferable to add 5% by weight or more to the composition. Inorganic fillers to be used include talc, graphite, wollastonite, clay, mica, kaolin, calcium silicate, shirasu balloon, silica, gypsum, molybdenum disulfide, and metal carbides due to their surface properties, thermal stability, and physical properties. For example, talc, mica, and wollastonite are particularly preferred in terms of heat resistance and falling weight impact strength.

The average particle size of the filler is preferably 30 μm or less in terms of appearance and physical properties. Examples of the fibrous reinforcing agent include glass fibers, carbon fibers, graphite fibers, metal carbide fibers, metal nitride fibers, aramid fibers, and phenolic resin fibers, with glass fibers being particularly preferred.
The diameter thereof is usually 15 μm or less, and it is preferably surface-treated to strengthen plastic or treated with a sizing agent. The amount of the inorganic filler blended is 0 to 60% by weight based on the total composition, and the blended amount of the fibrous reinforcing agent is 0 to 50% by weight based on the total composition. The total amount of both is preferably 20 to 60% by weight based on the total composition. Depending on the purpose and use, the composition of the present invention may further include stabilizers such as antioxidants, ultraviolet absorbers, etc., as well as plasticizers, lubricants, flame retardants, antistatic agents, colorants, mold release agents, metal powders, etc. Various additives can be blended. Furthermore, a polyamide resin may be blended in an amount of 50% by weight or less based on the polyester resin. The method for producing the polyester resin composition of the present invention is not particularly limited, and any method may be used. For example, a polyalkylene glycol compound and an olefin elastomer are added in the late stage of polymerization of a polyester resin, and after melt-kneading, other additives such as an inorganic filler and a fibrous reinforcing agent are added to the extruder or two. A method of melt-kneading all the ingredients in an extruder or kneader after pre-mixing all the ingredients, a method of pre-mixing all the ingredients and then melt-kneading them in an extruder or kneader, Examples include a method of melt-kneading other components. In addition, in compositions containing inorganic fillers and/or fibrous reinforcing agents, these are kneaded into a part of the polyester resin or elastic body, and then mixed into the composition consisting of the remaining polyester resin, elastic body, and polyalkylene glycol compound. Any blending method such as blending may be adopted. When using an epoxy group-containing compound, a catalyst such as sodium, potassium, or calcium salts of fatty acids such as stearic acid or montanic acid is used in combination to promote the reaction between the epoxy group and the COOHlOH of the resin and/or elastic body. It is preferable to do so. The composition of the present invention does not require any special molding method or molding conditions, and can be molded under the usual molding conditions for crystalline thermoplastic resins, yielding molded articles with excellent heat-resistant dimensional accuracy and mechanical properties.

Therefore, in addition to molding various molded parts, films, sheets such as plates, fibrous materials, tubular materials, containers, etc., it can also be used as a coating agent, coating agent, adhesive, or as an improving agent for other resins. It can be used as The present invention will be explained below with reference to Examples.

Note that parts and percentages in the examples are based on weight. Further, the characteristics of the test pieces in the examples were evaluated by the following test method. (1) Mold releasability and surface properties of molded products Mold releasability was determined by mold separation and spool slippage when molding a disk with a diameter of 100 mm and a thickness of 3111 mm.

In addition, the surface characteristics were judged by the surface gloss and flow pattern of the disk. ◎: Extremely good 0: Good △: Fairly good ×
：Poor It is expressed as the energy value at which the crack occurs.

(5) Heat shrinkage rate When a disk with a diameter of 100 mm and a thickness of 3 mm is formed, the length at the 4th angle to the side gate is 101, and the length after processing at 160 degrees C for 1 hour in a gear oven is l. , was calculated using the following formula.

(6) Amount of heat distortion According to the heat distortion temperature measurement method of ASTM D648, thickness of test piece % inch, load 18,61<FtA
m. The temperature was raised at 120°C, and the amount of deformation was measured at 120°C.

Example 1 Polyethylene terephthalate (hereinafter abbreviated as PET, intrinsic viscosity 0.58, melting point 260°C), ethylene
Vinyl acetate copolymer (ethylene component 65%, Tg = approx. -
Melt index 60) at 20°C and 230°C,
Polyalkylene glycol compounds and talc (Hayashi Kasei Co., Ltd., Talcan Powder - PKl average particle size 10μ)
After pre-mixing in the ratio shown in 1, it was poured into the hopper of a 40m1φ2 vent extruder, and the cylinder temperature was 250-27.
A compound chip was obtained by melt-kneading at 5°C.

After drying this compound chip under reduced pressure at 120°C for 17 hours, a test piece was molded using an injection molding machine (Nissei Jushi Kogyo Co., Ltd. FS75) adjusted to a cylinder temperature of 270-275-27.5°C and a mold temperature of 90°C. The physical properties of the obtained molded article were evaluated and the results are shown in Table 1. As is clear from Table 1, the composition of the present invention, which uses a specific ethylene copolymer and a specific polyalkylene glycol compound in combination, exhibits improved moldability and is heat-resistant and dimensional stable when molded in a low-temperature mold. A molded product with good properties and high toughness was obtained.

On the other hand, comparative examples that do not contain polyalkylene glycol compounds, comparative examples that use ethylene glycol diglycidyl ether instead of polyalkylene glycol, and comparative examples that use polyalkylene glycol with a large molecular weight all have good moldability and physical properties. Comparative examples in which no ethylene copolymer was blended had insufficient toughness.

Example 2 The same PET as in Example 1 was used, olefin copolymer, polyalkylene glycol, talc with an average particle size of 10μ (Talcan Powder PKl Hayashi Kasei Co., Ltd.), length 3m7! t
After premixing glass chopped strands (Glasron Chopped Strand 486A1 Asahi Fiber Glass Co., Ltd.) and catalyst in the proportions shown in Table 2, they were charged into the hopper of a 40φ2 vented extruder, and the cylinder temperature was 250 to 275°C.
The mixture was melted and kneaded to obtain compound chips.

Using this compound chip, a test piece was molded in the same manner as in Example 1. The moldability and physical properties of the molded article were evaluated and the results shown in Table 2 were obtained. As is clear from Table 2, reinforcement P
When a specific ethylene copolymer and polyalkylene glycol glycidyl ether were used in combination with the ET composition, excellent moldability was exhibited, and a molded article with a small amount of thermal deformation and improved toughness was obtained.

Although not shown, molded products with better surface characteristics had higher heat distortion temperatures and superior dimensional accuracy at high temperatures with the same amount of reinforcing agent (glass fiber and talc). Example 3 Using the same PET as in Example 1, reinforcing compositions in which the amount of olefin copolymer and ethylene content were varied were molded and evaluated for physical properties in the same manner as in Example 2.

The results are shown in Table-3. As is clear from Table 3, the compositions of the present invention using a specific amount of a copolymer with a specific ethylene content in combination with polyalkylene glycol glycidyl ether provided improved moldability and toughness.

Comparative Example An injection molding test was conducted using the same composition as in Example 1 and Taki 5, except that 5 parts of polyethylene glycol (molecular weight 150) or ethylene glycol diglycidyl ether was used as a crystallization accelerator, and moldability and physical properties were evaluated.

The results are shown in Table-4.

Claims (1)

[Scope of Claims] 1 (A) 60 to 98.5 parts by weight of polyethylene terephthalate or a copolyester containing 80 mol% or more of ethylene terephthalate repeating units, (B) a polyalkylene glycol compound with a molecular weight of 200 to 5,000 0.5 to 10 parts by weight, and (C) a polyester resin composition containing 30 to 95 parts by weight of an ethylene component and 1 to 30 parts by weight of an olefinic elastomer having a glass transition point of 0°C or lower. thing. 2. The polyester resin composition according to claim 1, wherein the polyalkylene glycol compound is a polyalkylene glycol glycidyl ether having a polyoxyalkylene chain and an epoxy group. 3. The polyester resin composition according to claim 1 or 2, wherein the polyester resin composition contains a fibrous reinforcing agent and/or an inorganic filler.