JPS6356266B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic polyester composition that has excellent chemical resistance, particularly resistance to alcohol-mixed gasoline, and good melt moldability. Thermoplastic polyesters, represented by polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexane dimethylene terephthalate, etc., are used in mechanical parts, electrical parts, automobile parts, etc. due to their excellent properties. . On the other hand, due to the deterioration of the crude oil situation in recent years, there is a growing trend to use alcohol such as methanol and ethanol as an energy source, and in particular, research is being carried out around the world on the technology of using alcohol-mixed gasoline, in which alcohol is added to gasoline, as automobile fuel. has been done. However, although thermoplastic polyester has excellent properties, it has poor chemical resistance, especially resistance to alcohol-mixed gasoline, so when it is applied to applications that come into contact with alcohol-mixed gasoline, such as in automobiles, various properties may deteriorate. This tendency is particularly remarkable at high temperatures. In addition, thermoplastic polyester has low melt flowability due to its crystallinity, resulting in poor moldability and problems with dimensional accuracy, surface appearance, warpage, etc. of molded products. Increasing the molecular weight of the thermoplastic polyester may be considered as a method of improving the alcohol-mixed gasoline resistance of this thermoplastic polyester, but simply increasing the molecular weight has a small effect on improving the alcohol-mixed gasoline resistance. Since the melt fluidity during molding is further reduced, a good molded product cannot be obtained. Therefore, the present inventors conducted intensive studies to obtain a thermoplastic polyester that has excellent chemical resistance such as alcohol resistance and mixed gasoline resistance, high melt flowability, and good melt moldability. However, the present invention was accomplished by discovering that the above object can be effectively achieved by incorporating a specific monoglycidyl ester compound. That is, in the present invention, based on 100 parts by weight of a thermoplastic polyester whose acid component is at least one selected from terephthalic acid and isophthalic acid and whose diol component is butylene glycol,
The present invention provides a thermoplastic polyester composition containing 0.01 to 5 parts by weight of a monoglycidyl ester compound represented by the following general formula () and containing no halogenated flame retardant. (In the formula, R represents an organic substituent having 11 to 30 carbon atoms.) The thermoplastic polyester used in the present invention is substantially formed by the condensation of at least one component selected from terephthalic acid and isophthalic acid and butylene glycol. Specific examples include copolymerized polyesters such as polybutylene terephthalate (PBT) and polybutylene terephthalate/isophthalate (PBT/I). In addition, these polyesters further contain other third components within 30 mol%, such as adipic acid, sebacic acid, dodecanedioic acid, hexadecanedicarboxylic acid, octadecanedicarboxylic acid, dimer acid, phthalic acid, 4,4'-
diphenyldicarboxylic acid, sulfoisophthalic acid,
ethylene oxide adduct of bisphenol A,
etc. can be copolymerized. Further, even a blend formed by mixing two or more of these thermoplastic polyesters can be applied to the present invention. Furthermore, the thermoplastic polyester may be other thermoplastic resins (e.g., polyethylene, polypropylene, acrylic resin, fluororesin, polyamide, polyacetal, polycarbonate, polysulfone, polyphenylene oxide, etc.), thermosetting resins (e.g., phenolic resin, melamine resins, polyester resins, silicone resins, epoxy resins, etc.) and soft thermoplastic resins (e.g. ethylene/vinyl acetate copolymers, polyester elastomers,
ethylene/propylene terpolymers, etc.) may also be contained in small proportions. The monoglycidyl ester compound used in the present invention is a compound represented by the above general formula (), and specifically, pelargonic acid glycidyl ester, stearic acid glycidyl ester, lauric acid glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester , versatate glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, linolenic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, etc., and two or more of these can also be used in combination. Furthermore, the organic substituent R in the general formula may contain a halogen such as chlorine or bromine. The amount of these monoglycidyl ester compounds added is 0.01 parts by weight per 100 parts by weight of thermoplastic polyester.
-5 parts by weight, preferably 0.05-3 parts by weight.
If the amount added is more than 5 parts by weight, the appearance of the molded product will deteriorate, leading to a decrease in commercial value, and if it is less than 0.01 part by weight, the effect of improving the alcohol resistance of mixed gasoline cannot be obtained, which is not preferable. The heat resistance, particularly the thermochromic property, of the composition of the present invention is improved by adding a stabilizer. These stabilizers include phosphoric acid, phosphorous acid, hypophosphorous acid, phosphonic acid,
Phosphorus compounds such as phosphinic acid or derivatives such as their metal salt compounds and ester compounds (e.g. phenylphosphonic acid, phenylphosphinic acid,
diphenylphosphinic acid, polyphosphonate, dialkylpentaerythritol diphosphite,
dialkyl bisphenol A diphosphite),
Hindered phenol compounds, thioethers,
Compounds containing sulfur such as dithioate salts, mercaptobenzimidazole, thiocarbanilide and thiodipropionic acid esters, and organic tin compounds such as stanmalate and dibutyltin monoxide can be used. The amount of these stabilizers added is 0.01 to 2 parts by weight per 100 parts by weight of thermoplastic polyester. In order to improve the heat distortion temperature and rigidity of the composition of the present invention, fibrous substances such as glass fiber, asbestos, calcium metasilicate, potassium titanate, and ceramic fiber can be added, and the amount of these additions is usually 100% of the thermoplastic polyester. For parts by weight,
It ranges from 5 to 70 parts by weight. Additionally, fillers such as glass beads, talc, mica, calcium carbonate, titanium oxide, barium sulfate, calcium oxide, aluminum oxide, and the like can be similarly added. In order to improve the moldability of the composition of the present invention, lubricants such as silicone oil, montanic acid wax (ester, half ester, salt), stearic acid ester, ethylene bis stearylamide, etc. can be blended, and the amount of these additions is limited. It is usually 0.05 to 5.0 parts by weight per 100 parts by weight of thermoplastic polyester. In addition, known additives such as dyes, pigments, nucleating agents, plasticizers, ultraviolet absorbers, foaming agents, and thickeners can be added to the composition of the present invention. The method for producing the composition of the present invention is not particularly limited, but preferably the thermoplastic polyester, monoglycidyl ester compound and other desired additives are uniformly melted using an extruder at a temperature equal to or higher than the melting point of the thermoplastic polyester. One method is kneading. The obtained composition can be molded by any commonly known method such as injection molding or extrusion molding. Molded articles obtained from the composition of the present invention have excellent chemical resistance and melt moldability, and can be used for various purposes such as electrical/electronic parts, automobile parts, and precision equipment parts such as watches. However, it is particularly useful for automotive parts applications that take advantage of its alcohol-resistant mixed gasoline properties. The present invention will be explained in detail below with reference to Examples. In the examples, the relative viscosity is a value measured at 25° C. for a 0.5% polymer solution using ortho-chlorophenol as a solvent. The numbers in the examples indicate parts by weight. Example 1 Polybutylene terephthalate with a relative viscosity of 1.55
100 parts of the various monobricidyl ester compounds shown in Table 1 were dry blended, and the mixture was melt mixed and pelletized using an extruder with a 40 mmφ screw set at 250°C. The pellets obtained were then heated to 250℃ for 10 minutes.
An ASTM No. 1 dumbbell test piece was molded at a mold temperature of 80°C using a screw-in-line type injection molding machine with an injection capacity of 1 oz. At this time, the injection pressure (lower limit injection pressure) for obtaining a molded article was measured as a measure of fluidity. Next, this test piece was placed in an autoclave filled with alcohol mixed gasoline (gasoline/ethanol = 85/15, volume ratio), and the temperature was adjusted to 80°C. Remove specimens at various times and perform ASTM
A tensile test was conducted according to the D638 method, and the processing time until the strength reached 50% (strength retention rate 50%) relative to the initial tensile strength was determined. These results are shown in Table 1.

【table】

[Table] As is clear from Table 1, the compositions of the present invention (Nos. 1 to 5), which are made by adding a monoglycidyl ester compound to polybutylene terephthalate, have excellent alcohol resistance and mixed gasoline properties.
The lower limit injection pressure is low and melt moldability is good. On the other hand, when polybutylene terephthalate is simply made to have a high degree of polymerization (No. 7) and when a diglycidyl ester compound is added (No. 8), the effect of improving the alcohol resistance of mixed gasoline is not only insufficient but also poor. Does not exhibit melt moldability. Example 2 Polybutylene terephthalate with a relative viscosity of 1.43
100 parts of glass fiber, 35 parts of glass fiber, and 2.0 parts of versatate glycidyl ester as a monoglycidyl ester compound were mixed in a 50 volume V-blender, and the mixture was melted and pelletized in an extruder having a screw of 65 mmφ. Next, injection molding and alcohol mixed gasoline resistance were evaluated in the same manner as in Example 1, and the lower limit injection pressure during molding was 38 Kg/cm ² -G.
The test piece showed good resistance to alcohol mixed gasoline in 65 days until the strength retention rate reached 50%. On the other hand, when similar measurements were performed on a composition to which no monoglycidyl ester compound was added, the lower limit injection pressure was 46 kg/cm ² -G, and the number of days required to reach a strength retention rate of 50% was 19 days.

Claims (1)

[Scope of Claims] 1 The following general formula () is applied to 100 parts by weight of a thermoplastic polyester whose acid component is at least one selected from terephthalic acid and isophthalic acid and whose diol component is butylene glycol.
Monoglycidyl ester compound represented by 0.01
A thermoplastic polyester composition which does not contain a halogenated flame retardant and contains up to 5 parts by weight of a halogenated flame retardant. (In the formula, R represents an organic substituent having 11 to 30 carbon atoms.)