JPS5910700B2 - polyester resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyester resin compositions with improved impact resistance and low temperature moldability.

More specifically, the present invention relates to a novel polyester resin composition that exhibits excellent moldability when molded at a low mold temperature of 100° C. or lower and provides molded products with improved toughness. Polyethylene terephthalate has excellent heat resistance, chemical resistance, mechanical properties, electrical properties, etc., and is widely used in many industrial products as fibers and films.

However, when it is intended to be used for various purposes as injection molded products, there are long disadvantages in terms of molding and physical properties. In particular, poor moldability due to a low crystallization rate at low temperatures and brittleness due to the formation of large spherulites significantly limit its use as an injection molding material or an extrusion molding material. In other words, although polyethylene terephthalate is originally a crystalline polymer, it has a high second-order transition point (70°C) and a high minimum temperature required for crystallization.
The crystallization start temperature (exothermic peak temperature) is approximately 125°C when the temperature is raised at 20°C/min using a differential scanning calorimeter). When molding is performed at a mold temperature below ℃, sufficient crystallization does not occur, resulting in poor appearance and physical properties of the molded product.When such a molded product is heated to a temperature above the secondary transition point, dimensional stability and shape deteriorate. Stability is extremely poor and cannot withstand use. On the other hand, if the mold temperature is set to 70° C. or less and the molded product is rapidly cooled, an amorphous and uniformly transparent molded product can be obtained. Although such an amorphous molded article can be crystallized by high-temperature heating, it has the disadvantage of causing significant dimensional changes and warping due to volumetric shrinkage caused by crystallization. Conventionally, in order to promote crystallization of crystalline thermoplastic resins, about 0.05 to 5% by weight of cutting agents, particularly inorganic fillers such as talc and titanium oxide, have been blended.

In polyethylene terephthalate, the crystallization rate during high-temperature molding can be improved by adding a cutting agent, but it is difficult to shift the crystallization initiation temperature to the lower temperature side.
Even when a large amount of % by weight or more is added, the crystallization initiation temperature decreases by at most about 10°C, and the surface crystallization of the molded product in low-temperature mold molding at 100°C or less is completely insufficient. In addition, 0.05 to 3% by weight of inorganic fillers such as talc and clay and 0% of polyepoxide are added to polyethylene terephthalate.
．． It is also known in Japanese Patent Publication No. 47-2193, Japanese Patent Publication No. 47-3
Although it is known from Publication No. 3256, etc., the polyepoxides such as ethylene glycol diglycidyl ether, butanediol diglycidyl ether, and 4-isopropenicyclohexane diepoxide described in the publication still have insufficient crystallization promoting effect. Not only is it impossible to obtain a molded product with excellent surface properties and physical properties using a low-temperature mold of 100°C or less, but blending a large amount of polyepoxide causes problems such as gelation, making it difficult to put it into practical use. is difficult. On the other hand, regarding impact resistance, a method of incorporating glass fiber is known as disclosed in Japanese Patent Publication No. 44-457.

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. Also, U.S. Patent No. 3,466,348
A method of blending amorphous polyester as disclosed in the specification of Japanese Patent Publication No. 46-5224, Japanese Patent Publication No. 46-5224, Japanese Patent Publication No. 46-5224,
6-5225, Japanese Patent Publication No. 46-15227, and Japanese Patent Application Laid-Open No. 51-144452, methods of blending various rubber-like substances are also known, but in all cases the heat distortion temperature It has drawbacks such as a decrease in heat resistance, a decrease in elastic modulus, and a decrease in bending strength. The inventors of the present invention have arrived at the present invention as a result of intensive research aimed at developing a polyester resin composition that exhibits a small decrease in elastic modulus, high toughness, and excellent low-temperature crystallinity and moldability.

That is, the present invention comprises 60 to 98.8 parts by weight of polyethylene terephthalate or a copolyester resin containing at least 80 mol% of ethylene terephthalate repeating units, 1 to 30 parts by weight of polyamide resin, and polyalkylene glycol or its monoether or polyhydric polyester resin. A mono- or polyglycidyl ether of polyoxyalkylene glycol or a derivative thereof selected from the group consisting of alcohol/alkylene oxide adducts, and containing an epoxy compound having a molecular weight of 5000 or less in a proportion of 0.2 to 10 parts by weight. The present invention relates to a polyester resin composition. Since the composition of the present invention effectively lowers the crystallization initiation temperature, the composition has an 80-1
Even by molding in a mold at a low temperature of about 00° C., it is possible to provide an injection molded product that is uniformly and highly crystallized up to the surface layer and has excellent surface gloss with a short residence time in the mold.

Furthermore, in addition to excellent mold releasability and surface properties when molded in low-temperature molds, the resulting molded products have excellent dimensional stability at high temperatures.
It is characterized by excellent shape stability. Furthermore, the molded product exhibits extremely low warp deformation at high temperatures and has excellent heat resistance and toughness. Even if polar polymers such as polyamide resin are blended to increase the bonding strength between the spherulite interfaces and molecules of polyethylene terephthalate and improve its toughness, the compatibility is poor, resulting in a sea-island structure, resulting in poor physical properties such as strength and elongation. decreases.

Further, it is disclosed in a comparative example in JP-A-51-103191 that the physical properties are not improved even if solid phase polymerization is performed after blending. However, in the present invention, by blending a specific epoxy compound, the compatibility of both resins can be improved and the strength and elongation can be significantly increased.
The crystallization promoting effect of a specific epoxy compound is due to the fact that the mobility of the glycol moiety of polyethylene terephthalate is activated by the polyoxyalkylene chain of the specific epoxy compound, which has a low secondary transition point, and the epoxy group and the terminal end of the resin are activated. This is thought to be because the resin reacts at least partially with the group, inducing molecular orientation of the resin within the mold during injection molding.
In any case, it is completely surprising that the crystallization initiation temperature can be lowered to below 100°C. In addition, the toughness improvement effect of a specific epoxy compound has a large affinity between the polyester resin and the specific epoxy compound, and the polyester resin is modified to improve its compatibility with the polyamide resin, and at least a part of the epoxy compound It is thought that the group also reacts with the polyamide end group to improve the adhesion between both resins, and that the intermolecular force due to the hydrogen bonds of the polyamide resin contributes to exhibit improved toughness. It is also believed that this is due to the fact that the adhesiveness between the inorganic filler and the resin increases when the inorganic filler is added to the composition. The polyester resin used in the present invention is polyethylene terephthalate or a copolymerized polyester resin containing at least 80 mol%, 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 1,4- or 2,6-dicarboxylic acid, diphenyl ether 4,4'-dicarboxylic acid, adipic acid, sebacic acid, etc., 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)propane and the like are exemplified. Furthermore, oxyacids such as P-oxybenzoic acid and P-hydroxyethoxybenzoic acid can also be used as copolymerization components. Furthermore, a trifunctional component may be copolymerized in a small amount so as not to impair moldability.
The intrinsic viscosity of the polyester resin is usually 0.4 or more, preferably 0.5 or more, and more preferably 0.5 or more, and the intrinsic viscosity of the polyester resin is determined by measuring it at 30°C with a phenol/tetrachloroethane mixed solvent (6/4 weight ratio) solution. It is particularly preferable that it is .55 or more. Further, the polyamide resin used in the present invention has the general formula NH2 (CH2).

ω-amino acid or NH (CH2) denoted by COOH (n=3-11).

Polyamides obtained from lactams represented by CO (n=3-11) diamines such as hexamethylene diamine, dodecamethylene diamine, m-xylene diamine and adipic acid, sebacic acid, dodecanoic acid, isophthalic acid, terephthalic acid Examples include homopolymer resins or copolymer resins obtained from combinations of dicarboxylic acids such as nylon 6, nylon 6,6, nylon 11.
, nylon 12, nylon 6, 12, etc. Note that the molecular weight of the polyamide resin is preferably 10,000 or more. Furthermore, the epoxy compound used in the present invention is an epoxy compound having a polyoxyalkylene chain and at least one glycidyl group in the molecule, and polyoxyalkylene glycol or its monoether or polyhydric alcohol/alkylene oxide adduct. mono- or polyglycidyl ether of

Preferably, for example, a general formula, where A: a hydrocarbon group, especially a C1-C5 aliphatic hydrocarbon group, hydrogen or a glycidyl group R: a C1-5 aliphatic hydrocarbon group n: a polyalkylene represented by an integer of 2 or more Examples include glycol glycidyl ether.

Specific compounds include mono- or diglycidyl ether of polyethylene glycol, mono- or diglycidyl ether of polypropylene glycol, mono- or diglycidyl ether of polytetramethylene glycol, mono- or diglycidyl ether of polyneopentyl glycol, and polyethylene glycol/polypropylene glycol. Examples include mono- or diglycidyl ether of a copolymer, mono- or diglycidyl ether of a polyethylene glycol/polytetramethylene glycol copolymer, monoglycidyl ether of phenoxypolyethylene glycol, and monoglycidyl ether of ethoxypolypropylene glycol. In addition to the general formula, mono- or polyglycidyl ethers of polyhydric alcohol/alkylene oxide adducts such as glycerin/alkylene oxide adducts, neopentyl glycol/alkylene oxide adducts, and pentaerythritol/alkylene oxide adducts are also listed as preferred compounds. It will be done. However, it is not limited to these. The average molecular weight of the epoxy compound is 5,000 or less, and more preferably about 300 to 1,500 among 200 to 30,001. If the molecular weight is too high, the compatibility with polyester will decrease,
The crystallization promoting effect is lost. The epoxy compound is particularly preferably a polyepoxy compound having an average of 1.2 or more epoxy groups in the molecule. The epoxy compound preferably contains a polyoxyalkylene chain and an epoxy group in the same molecule, but it is not a mixture that reacts with the resin to produce an epoxy compound having a polyoxyalkylene chain. Good too. In the composition of the present invention, 60 to 98.8 parts by weight of polyester resin and 1 part by weight of polyamide resin are used.
30 parts by weight and 0.2 to 10 parts by weight of the epoxy compound having a polyoxyalkylene chain.

If the amount of the polyamide resin is less than 1 part by weight, the improvement in strength and elongation will be insufficient, while if it exceeds 30 parts by weight, the hygroscopicity of the molded product will increase and the electrical properties will deteriorate. Preferably, the ratio is 2 to 20 parts by weight of the polyamide resin to 72 to 97 parts by weight of the polyester resin. Furthermore, if the epoxy compound is less than 0.2 parts by weight, improvements in both moldability and strength and elongation are insufficient, while if it exceeds 10 parts by weight, gelation may occur during kneading or molding, or the physical properties of the molded product may deteriorate. It has disadvantages such as causing The preferred amount of the epoxy compound is 8 to 1 part by weight per 92 to 99 parts by weight of the polyester resin and polyamide resin. When an inorganic filler such as talc or a fibrous reinforcing agent such as glass fiber is added to a polyester resin, rigidity and heat resistance are improved, but elongation and impact strength are reduced, making the product unusable. However, a composition in which an inorganic filler or a fibrous reinforcing agent is blended with the composition of the present invention can similarly improve rigidity and heat resistance, and can provide an excellent molded article with high elongation and impact strength. In particular, it is preferable to incorporate an inorganic filler also from the viewpoint of moldability. Examples of inorganic fillers that can be blended include talc, clay, kaolin, mica, asbestos, wollastonite, silicates such as calcium silicate, silica, gypsum, and graphite, with silicates being particularly preferred. .
The particle size of the inorganic filler is preferably 20 μm or less in view of the appearance and physical properties of the molded product. The amount incorporated is usually 60% by weight or less, preferably 15 to 45% by weight based on the total composition.
It is. If it exceeds 60% by weight, there will be disadvantages such as a decrease in fluidity during molding and a decrease in the physical properties of the molded product.

Examples of fibrous reinforcing agents include glass fibers, carbon fibers, graphite fibers, metal carbide fibers, metal nitride fibers, aramid fibers, phenol resin fibers, etc. Glass fibers are particularly preferred, and their diameter is 15 μm. It is preferable to use the following surface treatment for plastic reinforcement or treatment with a sizing agent.

The amount incorporated is usually 50% by weight or less, preferably 3 to 40% by weight, based on the total composition. Furthermore, depending on the purpose and use, the composition of the present invention may contain stabilizers such as antioxidants and ultraviolet absorbers, and flame retardants such as ethyl carbonate oligomers of tetrapromobisphenol compounds and tetrapromobisphenol compounds. Cyanuric acid ester oligomers, epoxy resin oligomers of tetrapromobisphenol compounds, decabromodiphenyl ether, mold release agents such as higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, plasticizers, lubricants, antistatic agent,
Various additives such as colorants and metal powders can also be blended.

The method for producing the polyester resin composition is not particularly limited, and any method may be used.

For example, a method in which polyamide resin and epoxy compound are mixed and kneaded in the latter stage of polyester polymerization, or a method in which a powder or liquid epoxy compound is premixed with pellet or powder polyester resin and polyamide resin, and then melted in an extruder or seconder. In the case of compositions containing inorganic fillers, the entire composition is premixed and then melt-kneaded using an extruder or second machine, or the inorganic filler is added after melt-kneading both resins and the epoxy compound. There are a method of blending, a method of melt-kneading a polyamide resin and an epoxy resin with a filler-containing polyester resin, and the like. At this time, in order to promote the reaction between the epoxy group and the carboxyl group or hydroxyl group, it is preferable to use a catalyst such as a sodium, potassium, or calcium salt of a fatty acid such as stearic acid or montanic acid. In a composition containing a reaction accelerator, it is particularly preferable to melt-knead the polyester resin and the epoxy compound, and then mix and melt-knead a mixture of the polyamide resin and the reaction accelerator or a polyamide resin coated with the reaction accelerator. The composition of the present invention does not require any special molding method or reshaping conditions, and can be molded under normal thermoplastic resin molding conditions, giving molded products with excellent heat-resistant dimensional accuracy and mechanical properties.

Therefore, in addition to forming various molded parts, films, sheet-like objects such as plates, fibrous objects, tubular objects, containers, etc., it can also be used as a coating material, coating material, adhesive, or as a modifier for other resins. You can also use it. The present invention will be explained below with reference to Examples.

Note that parts and percentages in the examples are based on weight. Also,
Characteristics of the test pieces in the examples were evaluated by the following method. (1) Mold releasability, surface characteristics of molded products Mold releasability is 100cm in diameter and 3m7 in thickness! Judgment was made based on mold separation and spool falling out when molding a No. 1 disc.

In addition, the surface characteristics were judged by the surface gloss and flow pattern of the disk. ◎: Extremely good ○: Good Δ: Fairly good X: Poor ×X: Extremely poor (2) Bending test ASTM D-790 (3) Falling weight impact strength Using a DuPont type tester, an injection molded product with a thickness of 3 mm was tested with a tip radius of This is the energy value at which a crack occurs at 6.3 mu.

(4) Heat shrinkage rate When a disk with a diameter of 100 mm and a thickness of 3 mm is formed, the length at an angle of 453 to the side gate is 101, and the length after processing for 160 C in a gear oven for 1 hour is 2.
It was calculated using the following formula.

(5) Heat deformation amount According to the heat deformation temperature measurement method of ASTM D-648, the test piece was heated to a thickness of 1/8 inch and a load of 18.6 kg/d.
The amount of deformation at 120℃ was measured by pilgrimage.

Example 1 Polyethylene terephthalate (hereinafter abbreviated as PET, intrinsic viscosity 0.58, melting point 260°C), polyamide resin (nylon 6, relative viscosity 2.5 determined at 25°C in a 1% solution of 96% sulfuric acid) and epoxy compound were prepared in advance. After mixing, it was put into the hopper of a 30 mmφ PCM3O twin screw extruder (Ikegai Tekko Co., Ltd.), and the cylinder temperature was 280-280-2.
The mixture was melt-kneaded at 80°C to obtain pellets.

The obtained pellets were dried under reduced pressure at 120°C for 17 hours, and then molded into test pieces using an injection molding machine FS75 (manufactured by Nissei Jushi Kogyo Co., Ltd.) with a cylinder temperature of 270-275-275°C and a mold temperature of 90°C. In addition, as a comparative example, PE
Test pieces were similarly molded from T alone, a blend of PET and nylon 6, and a blend of PET and an epoxy compound.

The physical properties of the obtained test piece were evaluated and the results are shown in Table 1.

The composition of the present invention, which is a blend of a polyamide resin and a specific epoxy compound, showed improved moldability, and when molded in a low-temperature mold, it gave a molded product with good heat-resistant dimensional stability and high toughness.

Moreover, the comparative example in which no polyamide resin was blended showed that the toughness deteriorated on the contrary.

Furthermore, a comparative example in which a compound having no polyoxyalkylene chain was blended as an epoxy compound had insufficient moldability, heat-resistant dimensional stability, and toughness. Example 2 The same PET and nylon 6 as in Example 1 were used, and PE
T and the epoxy compound were melt-kneaded at 275°C to obtain pellets.

Further, nylon 6 and a reaction catalyst are added to this pellet275
Compound chips were obtained by melt-kneading at ℃. Using this chip, a test piece was molded in the same manner as in Example 1, and the moldability and physical properties were evaluated, and the results shown in Table 2 were obtained.

By further blending a catalyst into a composition containing a polyamide resin and an epoxy compound having a polyoxyalkylene chain, moldability was further improved, and a molded article with low heat shrinkage and high toughness was obtained.

On the other hand, epoxy compounds without polyoxyalkylene chains had poor moldability and dimensional stability as well as poor toughness even when used in combination with a catalyst. Example 3 PE used in Example 1
TI nylon 6 was used, and further an epoxy compound was added in the proportions shown in Table 3, talc with an average particle size of 10 μm (Talcan Powder PKl Hayashi Kasei Co., Ltd.), and glass chopped strands with a length of 3 mm (Glass Lon Chopped Strands) were added. 486A1 (Asahi Fiberglass Co., Ltd.), the catalyst was premixed and then put into the hopper of a 40φ2 vent extruder, and the cylinder temperature was 250.
The mixture was melt-kneaded at ~275°C to obtain compound chips.

After drying this compound chip at 120°C for 17 hours under reduced pressure, the cylinder temperature was 270-275-275°C.
A test piece was molded using an injection molding machine FS75 whose mold temperature was adjusted to 95°C. The moldability and physical properties were evaluated and the results shown in Table 3 were obtained.

When a polyamide resin and an epoxy compound having a polyoxyalkylene chain were blended into a reinforced PET composition, excellent moldability was exhibited, and a molded article with a small amount of thermal deformation and improved toughness was obtained. Although not shown, the better the surface characteristics of the molded product, the more the same (glass fiber +
talc) gave a high heat distortion temperature and excellent dimensional accuracy at high temperatures.

Example 4 Using PETI nylon 6 used in Example 1, Table-4
A test piece was molded from a composition containing the epoxy compound shown in Example 1 in the same manner as in Example 1, and the moldability and physical properties of the molded article were evaluated.

As is clear from Table 4, polyethylene glycol monoether monoglycidyl ether and nylon 6
The composition of the present invention containing the above had good moldability and physical properties.

Claims (1)

[Claims] 1. Polyethylene terephthalate or at least 80
selected from the group consisting of 60 to 98.8 parts by weight of a copolyester resin containing mol% of ethylene terephthalate repeating units, 1 to 30 parts by weight of a polyamide resin, and polyalkylene glycol or its monoether or polyhydric alcohol/alkylene oxide adduct A polyester resin composition comprising 0.2 to 10 parts by weight of an epoxy compound which is a mono- or polyglycidyl ether of a polyoxyalkylene glycol or a derivative thereof and has a molecular weight of 5,000 or less. 2. The polyester resin composition according to claim 1, wherein the polyester resin composition contains a fibrous reinforcing agent and/or an inorganic filler.