JPS6155536B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyester resin compositions with improved mechanical properties, particularly impact resistance. Since polyethylene terephthalate has excellent physical and chemical properties, it is widely used as a molding material for fibers, films, etc., along with polyamide. However, while polyamide was developed early as an injection molding or extrusion material, the application of polyethylene terephthalate in this field has been significantly delayed due to several drawbacks. This is mainly due to the two reasons mentioned above: polyethylene terephthalate has a higher crystallization onset temperature and a lower crystallization rate during low temperature molding than polyamide, resulting in poor moldability and low impact resistance. Regarding moldability improvement, there is a method using a high-temperature mold of 130 to 150°C as described in Japanese Patent Publication No. 18788, Japanese Patent Publication No. 7542/1973, and Japanese Patent Publication No. 1973.
−15024 Publication, Special Publication No. 47-3026, Special Publication Sho
As described in Japanese Patent No. 47-11668 and the like, methods of blending inorganic or organic crystal nucleating agents or crystallization promoters are known. On the other hand, regarding impact resistance, a method is known in which a large amount of glass fiber is blended, as described in Japanese Patent Publication No. 44-457. However, blending a large amount of glass fiber has disadvantages such as high cost and the occurrence of strength anisotropy and warp deformation in the molded product.Also, impact values such as Izot impact, which have high energy to break but can cause cracks, are disadvantageous. is still insufficient. In order to solve this drawback, a method is known in which the impact resistance is improved by increasing the ductility by adding a rubber-like substance, as disclosed in Japanese Patent Application Laid-open No. 51-144452, but the elastic modulus and bending strength are It has drawbacks such as a decrease in heat resistance such as a decrease in heat distortion temperature, and a decrease in heat resistance such as a heat distortion temperature. The present inventors have solved these drawbacks of the conventional method, that is, the decrease in elastic modulus etc. is small and the amount of warp deformation is small.
Moreover, as a result of intensive research to develop a polyester resin molding material with high toughness, the present invention was achieved.
That is, the present invention relates to polyethylene terephthalate or copolyester resins containing at least 80 mol% ethylene terephthalate repeating units.
0.5 urethane-modified epoxy resin per 100 parts by weight
It is characterized by being blended in a proportion of ~20 parts by weight. Conventionally, it has been known that when a general-purpose epoxy resin is blended with polyethylene terephthalate, toughness is improved by increasing the molecular weight, but even if the optimal composition is selected, crystallized molded products have the disadvantage of exhibiting bending fracture. On the other hand, molded products obtained from compositions containing the urethane-modified epoxy resin of the present invention are extremely strong without causing bending breakage. The increase in toughness is particularly remarkable in reinforced polyester resins containing glass fibers and inorganic fillers. This increase in toughness cannot be explained solely by a normal increase in molecular weight, which is completely surprising. The reason for this is not clear, but it is because the urethane-modified epoxy resin, which has flexibility and intermolecular force due to hydrogen bonds, reacts with the polyester resin by introducing urethane bonds into the epoxy resin, giving it flexibility. considered to be a thing. It is also believed that urethane modification improves the compatibility between the epoxy resin and the polyester resin and allows them to react uniformly, which also contributes to the improvement in toughness. Furthermore, in a composition containing an inorganic filler, the effect becomes even more remarkable, and this is thought to be due to the effect of the urethane segment increasing the adhesive strength between the polyester resin and the inorganic filler. In any case, the idea is different from conventional glass fiber reinforcement or reinforcement using rubber-like materials. The polyester resin used in the present invention is polyethylene terephthalate or at least 80 mol%
As mentioned above, the copolyester resin preferably contains 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,
Examples include sebacic acid, and glycol components include propylene glycol, butylene glycol,
Examples include diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexanedimethanol, and 2,2-bis(4-hydroxyphenyl)propane. Moreover, oxyacids such as P-oxybenzoic acid and P-hydroxyethoxybenzoic acid can also be copolymerized. Furthermore, a trifunctional component may be copolymerized in a small amount within a range that does not impair moldability. The polyester resin preferably has an intrinsic viscosity of 0.5 or more, more preferably 0.55 or more, as determined by measurement at 30° C. with a phenol/tetrachloroethane mixed solvent (6/4 weight ratio) solution. Urethane-modified epoxy resins used in the present invention include polyethylene glycol, polypropylene glycol, polytetramethylene glycol,
Polyethylene glycol/polypropylene glycol block copolymers, polyols or polyether polyols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, polylactone diol, polyethylene adipate, polybutylene adipate, polyethylene sebacate, polypropylene sebacate. In addition to compounds containing at least two terminal hydroxyl groups such as polyester polyols, polyamide diols and polyamide diamines containing at least two terminal OH groups, COOH groups, NH ₂ groups, SH
an active hydrogen-containing compound having a group, etc., preferably an active hydrogen-containing compound having a molecular weight of 200 to 5000, particularly 300 to 3000, and 2,4-toluylene diisocyanate,
2,6-toluylene diisocyanate, 1,4-
Naphthylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-dimethyldiphenylmethane-4,4'-diisocyanate, 3. Aromatic polyisocyanates such as 3'-dichlorodiphenyldimethylmethane-4,4'-diisocyanate, diphenyl-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, isophorone diisocyanate, dicyclohexylmethane- Isocyanate groups and/or hydroxyl groups obtained by reacting polyisocyanates such as alicyclic polyisocyanates such as 4,4'-diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate and tetramethylene diisocyanate, preferably at the terminals. A urethane-modified epoxy resin having a urethane bond in the molecule and an epoxy group at the end, which is produced by further introducing an epoxy group into a urethane prepolymer having the following formula, is preferable. It is preferable to introduce an epoxy group by reacting a polyepoxy compound with the above-mentioned urethane prepolymer containing terminal isocyanate groups. It can also be produced by a method of reacting polyepoxy compounds having different epoxy groups, a method of reacting an isocyanate group-terminated urethane prepolymer with glycidol, glycidamide, glycidyl imide, etc. In addition, as polyepoxy compounds, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, glycerin, pentaerythritol, polyethylene glycol, polypropylene glycol, polyester diol,
Polyhydric alcohols such as neopentyl glycol, cyclohexanedimethanol, resorcinol,
Polyglycidyl ethers such as polyhydric phenols such as bisphenol A, bisphenol S, and tetrabromobisphenol A or their alkylene oxide adducts, terephthalic acid, hexahydrophthalic acid, succinic acid, glutaric acid, adipic acid, Polyglycidyl obtained by singly or copolymerizing ethylenically unsaturated epoxy compounds such as polyglycidyl esters of polyhydric carboxylic acids such as sebacic acid, itaconic acid, trimellitic acid, and polyester dicarboxylic acids, allyl glycidyl ether, and glycidyl methacrylate. Compound,
Esters of unsaturated carboxylic acids and polyhydric alcohols, esters of unsaturated alcohols and polycarboxylic acids, esters of unsaturated alcohols and unsaturated carboxylic acids, and esters obtained by oxidizing polyunsaturated compounds such as butadiene. In addition to polyepoxy compounds etc.
Examples of polyepoxy compounds containing an average of more than one epoxy group in the molecule include polyglycidyl compounds of amine compounds such as vinyl cyclohexene dioxide, triglycidyl isocyanurate, triglycidyl phosphate, hydantoin, and urea compounds. be able to. The urethane-modified epoxy resin preferably has an epoxy equivalent of 200 to 10,000, more preferably 400 to 5,000. Further, the amount of urethane modification (weight % of polyisocyanate residues in the epoxy resin) is usually preferably 2% by weight or more, particularly preferably 5% by weight or more. The upper limit is 70% by weight, preferably 50% by weight, from the standpoint of manufacturing and overall effectiveness. The amount of the urethane-modified epoxy resin blended is usually 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of the polyester resin. If the amount is too small, the improvement in physical properties will be insufficient, while if the amount is too large, problems such as gelation due to the epoxy equivalent and a decrease in thermal properties, elastic modulus and bending strength will occur depending on the composition. When inorganic fillers, glass fibers, etc. are added to polyethylene terephthalate, the rigidity and heat resistance are improved, but the physical properties, particularly elongation and impact strength, are reduced, making it unusable in many applications. However, in the composition containing the urethane-modified epoxy resin of the present invention, the elastic modulus is almost the same even in the reinforced composition, and the strength and elongation can be improved, which is a great advantage in industrialization. A fibrous reinforcing agent and/or an inorganic filler can be effectively incorporated into the composition of the present invention. Examples of inorganic fillers that can be incorporated include talc, clay, kaolin, mica, asbestos, silicates such as calcium silicate, silica, and gypsum, with silicates being particularly preferred. Further, the average particle size of the inorganic filler is usually 30μ or less, preferably 10μ or less. The amount incorporated is 60% by weight or less, preferably 15 to 40% by weight based on the total composition.
It is. Addition of an inorganic filler improves heat resistance, rigidity, and moldability, but if the amount exceeds 60% by weight, the fluidity during molding and the physical properties of the molded product deteriorate. Examples of fibrous reinforcing agents include glass fibers, carbon or graphite fibers, metal carbide or metal nitride fibers such as silicon carbide, silicon nitride, and boron carbide, aramid fibers, and phenolic resin fibers. Glass fiber is preferred. The diameter of the glass fibers is preferably 20μ or less, and may be roving or chopped strands. It is preferable that the glass fibers be surface-treated to improve adhesion such as silane treatment or chromium treatment, or treated 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.
It is. Furthermore, depending on the purpose, the composition of the present invention may contain resin stabilizers such as antioxidants, ultraviolet absorbers, plasticizers, lubricants, flame retardants, antistatic agents, colorants, crystallization promoters, mold release agents, Additives such as molybdenum disulfide may be added. 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 method in which urethane-modified epoxy resin is added in the latter stage of polyester polymerization and kneaded, a method in which pellet-shaped polyester resin is coated with urethane-modified epoxy resin and then melt-kneaded in an extruder or kneader, and pellet-shaped polyester resin A method in which a polyester resin, a urethane-modified epoxy resin, and optionally two of the inorganic fillers are coated with a urethane-modified epoxy resin, then sprinkled with an inorganic filler and a fibrous reinforcing agent, and then melt-kneaded using an extruder or kneader. It can be produced by a method of melt-kneading seeds and then further melt-kneading other components if desired. The resin composition of the present invention does not require any special molding method or molding conditions, and can be molded under normal polyethylene terephthalate molding conditions. In addition, the composition of the present invention can be widely used for molding various molded parts, sheets such as films and plates, fibrous materials, tubes, containers, etc., as well as coatings, adhesives, etc. It can also be used as a modifier for resins. The present invention will be explained below with reference to Examples. In addition,
Parts and percentages in the examples are by weight. In addition, the bending test in the examples was conducted according to ASTM D790, and the falling weight impact value was an energy value at which a crack would occur in a 3 mm thick injection molded product at a tip radius of 6.3 mm using a DuPont type impact tester. Example 1 Polybutylene adipate (average molecular weight 800) 100
2 parts and 32 parts of toluylene diisocyanate at 90°C.
The mixture was stirred for hours to obtain a urethane prepolymer containing terminal isocyanate groups. Next, this was mixed with polyglycidyl ether of bisphenol A (epoxy equivalent: approx.
500) and stirred at 140°C for 3 hours to obtain a urethane-modified epoxy resin. The urethane-modified epoxy resin was a yellow solid with a softening point of about 90°C, an epoxy equivalent of about 1000, and a urethane modification amount of about 8.4%. After premixing polyethylene terephthalate (hereinafter abbreviated as PET, intrinsic viscosity 0.58, melting point 260°C) and pellets of the above urethane-modified epoxy resin,
Pour into the hopper of a 30mmφPCM30 twin-screw extruder (Ikegai Tekko Co., Ltd.), and maintain the cylinder temperature at 280-280-280℃.
The mixture was melt-kneaded to produce pellets. The obtained pellets were dried under reduced pressure at 120°C for 17 hours, and then test pieces were molded 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 30°C. The obtained test piece was heated at 140℃ for 3
Table 1 shows the physical property values after the time heat treatment. As a comparative example, the physical properties were compared with those of test pieces molded and heat-treated from PET alone and from a composition containing PET and a normal epoxy resin.

【table】

[Table] The composition of the present invention containing a urethane-modified epoxy resin showed excellent toughness. On the other hand, in the comparative example in which a normal epoxy resin was blended, there was almost no improvement in both tensile elongation and breaking flexibility. Example 2 PET, the urethane-modified epoxy resin used in Example 1, talc with an average particle size of 10μ (Talcan Powder PK, Hayashi Kasei Co., Ltd.), and glass chopped strands with a length of 3 mm (Glass Ron Chopped Strand 486A) , Asahi Fiberglass Co., Ltd.) Table 2
After premixing in the composition ratio shown in , it is poured into the popper of a 40 mm φ 2 vent extruder, and the cylinder temperature is
Compound chips were obtained by melt-kneading at 250-275°C. After drying this compound chip at 120℃ for 17 hours under reduced pressure, the cylinder temperature was 270-275-275℃.
A test piece was molded using an FS75 injection molding machine with a mold temperature of 130°C. The physical properties of this test piece are shown below.
Shown in 2. In addition, as comparative examples, the physical properties of test pieces molded from compositions containing no urethane-modified epoxy resin and compositions containing ordinary epoxy resin instead of the urethane-modified epoxy resin were also evaluated and are shown in Table 2.

【table】

[Table] The composition of the present invention, in which a urethane-modified epoxy resin is blended with a reinforced PET molding material, has significantly improved toughness when compared not only to an additive-free composition but also to a composition containing a regular epoxy resin. showed that. Example 3 Polypropylene glycol (average molecular weight 400)
100 parts and 130 parts of toluylene diisocyanate at 85℃
The mixture was stirred for 2 hours to obtain a polyurethane prepolymer terminated with isocyanate groups. Add this polyurethane prepolymer to 350 parts of polyglycidyl ether of bisphenol A (epoxy equivalent: approximately 1000) and add 150 parts of
The mixture was stirred and reacted at ℃ for 3 hours. The obtained urethane-modified epoxy resin was a yellow solid with a melting point of about 90°C, an epoxy equivalent of about 2500, and a urethane modification amount of about 22%. Example 2 using the urethane modified epoxy resin
When the physical properties of a test piece molded with the same composition as No. 3 were evaluated, the tensile strength was 8.26 Kg/mm ² and the tensile elongation was
2.1%, bending elasticity modulus 727Kg/mm ² , falling weight impact strength 3.0
Kg·cm, indicating that the present invention significantly improves toughness.

Claims (1)

[Scope of Claims] 1. A polyester resin prepared by blending 0.5 to 20 parts by weight of a urethane-modified epoxy resin with 100 parts by weight of polyethylene terephthalate or a copolyester resin containing at least 80 mol% of ethylene terephthalate repeating units. Composition. 2. The polyester resin composition according to claim 1, wherein the polyester resin composition contains a fibrous reinforcing agent and/or an inorganic filler.