JP3498815B2 - Polyester resin composition for lamp case - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp case for automobiles and a sealed lamp case for lighting, which can be molded into a lamp case with a non-fog glass surface. The present invention relates to a polyester resin composition that can be used. [0002] Conventionally, as a lamp case, a sheet metal or a molded article of an unsaturated polyester resin composition has been used. However, recently, the shape of the lamp case has become complicated with the demand for increased functionality, and deep drawing workability has been required for the case material. Molded products are used. FIG. 1 is a plan view of an automobile lamp unit including an automobile lamp case 1, a glass 2 used in combination with the lamp case 1, and a lamp 3 sealed by the glass 2 and the lamp case 1. FIG. 2 shows an indoor lamp case 11, a glass 12 used in combination with the lamp case 11, a glass 12 and a lamp case 1.
1 shows the front of an indoor lamp unit with a lamp 13 sealed by 1; [0003] Further, since the unsaturated polyester resin composition conventionally used is inferior in moldability, a molded article composed of a polyethylene terephthalate resin composition or a polybutylene terephthalate resin composition having higher productivity is used. It has become. [0004] However, when the heat capacity of the lamp is large or when the lamp and the molded product are close to each other, the temperature of the molded product becomes high, so that decomposed products and compounds are sublimated from the molded product, and the molded product is sublimated. These precipitate on the glass surface combined with, and the problem that the glass surface becomes cloudy occurs. For this reason, applications of the polyethylene terephthalate and polybutylene terephthalate resin compositions have been limited. SUMMARY OF THE INVENTION [0005] The present invention has been made to solve the above problems, and its object is to provide good surface properties and moldability as well as long-term use. Another object of the present invention is to provide a polyester resin composition capable of forming a lamp case without fogging the glass surface. The present inventors have made intensive studies on a lamp case which does not fog the glass surface used in combination, and have finally completed the present invention. That is, the present invention relates to polyethylene terephthalate and / or
Alternatively, the polyester resin composition for a lamp case is characterized by containing 0.1 to 5.0 parts by weight of a carbodiimide compound and 0 to 150 parts by weight of an inorganic reinforcing material with respect to 100 parts by weight of polybutylene terephthalate. The polyethylene terephthalate and polybutylene terephthalate used in the present invention include:
Not only a polymer of ethylene glycol or butylene glycol and terephthalic acid (including a derivative thereof), but also a copolymerized polyester containing at least 80 mol% or more of ethylene terephthalate and / or butylene terephthalate repeating units. As the copolymerization component, a known acid component and / or glycol component can be used. That is, as the copolymerization component, for example, acid components such as isophthalic acid, naphthalene 1,4 or 2,6 dicarboxylic acid, diphenyl ether 4,4 dicarboxylic acid, adipic acid, sebacic acid; ethylene glycol, propylene glycol, butylene glycol, Glycol components such as diethylene glycol, neopentyl glycol, cyclohexane dimethanol, and 2,2-bis (4-hydroxyphenyl) propane; oxy acids such as p-oxybenzoic acid; The polyester resins (polyethylene terephthalate, polybutylene terephthalate) used in the present invention usually have an intrinsic viscosity of 0.3 when measured at 30 ° C. with a phenol / tetrachloroethane mixed solvent (6/4 weight ratio). 4 or more, preferably 0.5 or more. The mixing ratio of polyethylene terephthalate and polybutylene terephthalate is not particularly limited, and is 0 to 100 parts by weight of polyethylene terephthalate and 100 to 0 parts by weight of polybutylene terephthalate. Preferably, 20 to 80 parts by weight of polyethylene terephthalate is 80 to 20 parts by weight of polybutylene terephthalate, and more preferably, 30 to 70 parts by weight of polyethylene terephthalate is 70 to 30 parts by weight of polybutylene terephthalate. The above polyester resin is mainly used,
Aromatic polyesters such as polycyclodimethylene terephthalate and polyethylene naphthalate, polyesters such as polybutylene adipate and polylactone, polycarbonates and other thermoplastic resins may be mixed therein. In that case, the amount is preferably up to 20 parts by weight based on 100 parts by weight of polyethylene terephthalate and / or polybutylene terephthalate. If the amount exceeds 20 parts by weight, the intrinsic properties of the polyethylene terephthalate resin and the polybutylene terephthalate resin are lost, and the requirements of the present invention are not satisfied. The carbodiimide compound used in the present invention is represented by the following general formula (I). RN = C = NR (I) (wherein R represents a monovalent hydrocarbon group having 1 to 20 carbon atoms) A specific example of the carbodiimide compound represented by the general formula (I) is 2 , 2'dimethyldiphenylcarbodiimide, 2,6,2 ', 6'tetradiphenylcarbodiimide, 2,2'diethyldiphenylcarbodiimide, 2,6,2', 6'tetraethyldiphenylcarbodiimide, 2,2'diisopropyldiphenylcarbodiimide, , 6,2 ', 6'tetraisopropyldiphenylcarbodiimide and the like. Such garbodiimide compounds, even when used alone,
Two or more kinds may be used in combination. In the present invention, the compounding amount of the carbodiimide compound is 0.1 to 100 parts by weight of the polyester resin.
５5.0 parts by weight. Preferably it is 0.3 to 4.0 parts by weight, more preferably 0.5 to 3.0 parts by weight. When the amount is less than 0.1 part by weight, the effect of adding the carbodiimide compound is small, and when the amount exceeds 5.0 parts by weight, not only the surface properties and fluidity of the obtained molded article are reduced, but also the effect of reducing the amount of precipitation is not increased. Absent. Examples of the inorganic reinforcing material used as required in the present invention include fiber reinforcing materials such as glass fiber and carbon fiber, whiskers such as potassium titanate, talc, clay, wollastonite, montmorillonite, bentonite, and calcium carbonate. And the like. The inorganic reinforcing material increases the rigidity and heat deformation temperature of the molded product, and increases the dimensional stability. Therefore, depending on the application, 0 to 150 parts by weight is added to 100 parts by weight of the polyester resin. Preferably 5-12
0 parts by weight, more preferably 10 to 100 parts by weight. The blending amount of the inorganic reinforcing material may be determined according to the intended use. However, if it exceeds 150 parts by weight, the appearance of the molded product is unfavorably deteriorated. When a lamp case made of a composition containing ordinary polyethylene terephthalate resin or polybutylene terephthalate resin is used, a low molecular weight substance contained in the composition or a substance generated by thermal decomposition during use, for example, terephthalic acid Sublimates and precipitates on the glass surface, causing fogging on the glass surface. In the lamp case of the present invention, the fogging is considerably suppressed. It is considered that the reason is that the carbodiimide compound acts as a catcher for those low-molecular substances and thermal decomposition substances. Although carbodiimide compounds are conventionally known to be effective in preventing hydrolysis of polyester resins, it is surprising that use of such a carbodiimide compound in a lamp case is very effective in suppressing fogging. The polyester resin composition of the present invention may contain additives such as an antioxidant, an ultraviolet absorber, a plasticizer, a lubricant, a flame retardant, an antistatic agent, a release agent, and a colorant according to the purpose. it can. 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 of premixing all components and then mixing in an extruder or kneader, or melting other components into pellets obtained by kneading and blending any number of optional components in an extruder or kneader in advance A method of mixing is exemplified. The obtained composition does not require a special molding method or molding conditions, and can be molded into a lamp case by ordinary molding conditions of a thermoplastic polyester resin, for example, injection molding. The polyester resin composition for a lamp case of the present invention is molded from a resin composition containing a polyethylene terephthalate or polybutylene terephthalate resin and an inorganic reinforcing material, and therefore has good surface properties and moldability. In addition, by blending the carbodiimide compound in the resin composition, low molecular weight substances and pyrolytic substances generated during use are supplemented by the carbodiimide compound.
It seems that the fogging of the glass can be suppressed. EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. The parts and percentages in the examples are on a weight basis, and the heat distortion temperature of the injection-molded product was measured according to ASTM D648. Further, the amount deposited on the glass surface was evaluated as follows. 42 × 42 × 2 m obtained by injection molding
m was placed on a hot plate adjusted to a surface temperature of 200 ° C., covered with a glass weighing bottle having a diameter of 60 mm and a height of 80 mm, and treated for 420 hours. The upper surface of the glass weighing bottle was at about 50 ° C., and white powder mainly composed of terephthalic acid sublimated from the molded product was precipitated and devitrified on the inner surface. The amount of the sublimated precipitate was evaluated from the haze (permeability) of the glass weighing bottle and the change in weight. Examples 1 to 11, Comparative Examples 1 to 3 Polyethylene terephthalate resin, polybutylene terephthalate resin, glass fiber, talc, carbodiimide compound and montanic acid ester were premixed in the proportions shown in Table 1 and then twin-screw extruder Into a hopper and melt-kneaded to obtain a compound chip. After drying this compound chip at 130 ° C. for 4 hours, the cylinder temperature was 270 ° C.
The test piece was molded using an injection molding machine adjusted to the above conditions, and the amount of sublimated precipitates generated was evaluated by the method described above. As the carbodiimide compound, 2,6,2 ', 6'tetraisopropyldiphenylcarbodiimide (manufactured by Bayer; Stabacol P) was used. Table 1 and Table 2 show the results.
Shown in In Table 1, the sublimate precipitation amount indicates the weight% of the molded product, and the load in the measurement of the heat distortion temperature is:
It was 18.6 kg / cm ² . [Table 1] [Table 2] As is clear from Tables 1 and 2, it can be seen that the composition of the present invention has a reduced sublimation precipitation amount and maintains transparency. The results corresponded well with the results of the practical test of the lamp case. In addition, the composition of the present invention can reduce the amount of sublimate deposited at a high temperature and reduce clouding of the glass surface while maintaining good surface properties and moldability. Therefore, the degree of freedom in design is increased, and the device can be used at a high temperature, and can be applied to a purpose that could not be used conventionally.

[Brief description of the drawings] FIG. 1 is a plan view of an automotive lamp unit. FIG. 2 is a plan view of the indoor lamp unit. [Description of sign] 1: Lamp case for automobile 2: Glass 3: Lamp 11: Indoor lamp case 12: glass 13: Lamp

Claims (1)

(57) [Claim 1] 0.1 to 5.0 parts by weight of a carbodiimide compound and 0 to 150 parts by weight of an inorganic reinforcing material per 100 parts by weight of polyethylene terephthalate and / or polybutylene terephthalate. A polyester resin composition for a lamp case, comprising: