Thermoplastic polyester resin composition

Stock material or miscellaneous articles – Composite – Of epoxy ether

Reexamination Certificate

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C524S267000, C524S268000, C524S306000, C524S315000, C524S462000, C524S494000, C524S504000, C524S505000, C524S506000, C524S515000, C524S520000, C524S523000, C524S533000, C524S544000, C524S545000, C524S588000, C524S556000, C525S063000, C525S064000, C525S065000, C525S101000, C525S902000, C525S069000, C525S070000, C525S071000, C525S078000, C525S165000, C525S174000, C525S423000, C525S214000, C525S215000, C525S446000, C264S331210, C264S331110, C264S331180, C264S337000, C428S447000, C428S480000

Reexamination Certificate

active

06447913

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermoplastic polyester resin composition. More specifically, it relates to a thermoplastic polyester resin composition and a molded article thereof which have very excellent durability to alkaline solutions over a very long period of time. Furthermore, it relates to a thermoplastic polyester resin composition and a molded article thereof, which have excellent alkali resistance and excellent anti-stress qualities as well, and they are suitably used as materials or molded articles which need to keep good properties over a long period of time under sever environment.
PRIOR ART
Thermoplastic polyester resins, which are excellent in mechanical strength, electrical properties, and various other properties as crystalline thermoplastic resins, are used as engineering plastics for a variety of purposes including cars and electrical/electronic apparatuses. However, since the thermoplastic polyester resins cannot be said to secure durability to alkaline solutions over a long period of time, there has been a limit to the environment or purposes of use of the resins.
For example, some parts may be used in places frequently splashed with toilet detergents, bath detergents, bleachers, and snow-melting agents. These agents contain as components sodium hydroxide, sodium hypochlorite, sodium percarbonate, and calcium chloride and as a result, resin molded articles that may form the parts are exposed to an alkaline atmosphere.
When the resin molded articles are exposed to the alkaline atmosphere for a long period of time in the conditions where an excessive strain is imposed by screwing, press fit of metal, or caulking, the resin molded articles have encountered a problem of suffering both effects of the strain and alkali components that cause so-called environmental stress crack, thereby to develop cracks on the resin molded articles.
Polyester resins are general materials suitable for molding industrial parts. In many cases, an area fusion-bonded by jointing two or more interfaces of top of a flowing resin within a mold cavity on molding, or a weld area, is recognized in the molded articles formed of the resins. In general, the aforesaid environmental stress cracks are often produced in these weld areas of the molded articles, which has presented a problem.
Furthermore, an insert molding process of inserting the resin composition and a metal or an inorganic solid (hereinafter abbreviated as a “metal, etc.”) is a molding process that is applied in a wide variety of fields at present because the process can provide the parts effectively exhibiting both properties of the resin composition and the metal, etc. However, there occurs distortion in the circumference of the metal, etc., because the resin and the metal, etc. are different in shrinkage and linear expansion coefficient. Therefore, when insert molded articles are allowed to stand for a long period of time under the circumstances where the articles are splashed with alkaline solutions, cracks are produced in the circumference of the metal, etc., which has presented a problem.
DISCLOSURE OF THE INVENTION
The present inventors have intensively studied in view of the aforesaid problems to search for a thermoplastic resin excellent in long-term durability to alkaline solutions. As a results, the inventors have found that a composition, mainly containing a thermoplastic polyester resin and blended with impact resistance rendering materials, a silicone compound and/or a fluorine compound, an inorganic filler and a polyfunctional compound, has very excellent resistance against alkaline solutions, thus accomplishing the invention.
That is, the present invention provides a thermoplastic polyester resin composition in which
(A) a thermoplastic polyester resin is compounded with
(B) 1 to 25% by weight (in the total composition) of impact resistance rendering materials,
(C) 0.1 to 15% by weight (in the total composition) of a silicone compound and/or a fluorine compound,
(D) 1 to 50% by weight (in the total composition) of an inorganic filler, and
(E) 0.1 to 10% by weight (in the total composition) of at least one polyfunctional compound selected from the group consisting of epoxy compounds, isocyanate compounds and carboxylic dianhydrides. The thermoplastic polyester resin composition provided by the present invention comprises the aforesaid components (A), (B), (C), (D) and (E). The composition of the present invention has excellent resistance against alkaline solutions.
The present invention provides a molded article prepared by molding the aforesaid composition. The molded article can have a weld part in at least one portion, any one of a metal insert, a press-fitted member and a screwed part, or a press-fitted rigid member. The molded article includes insert molded articles prepared by insert molding of a metal or an inorganic solid.
DETAILED DESCRIPTION OF THE INVENTION
The invention is illustrated in detail below.
First, the thermoplastic polyester resin (A), that is the basic resin of the present invention, is polyesters prepared by polycondensation of dicarboxylic acid compounds and dihydroxy compounds, polycondensation of oxycarboxylic acid compounds, or polycondensation of the compounds consisting of these three components. It may be any of homopolyester and copolyester. Examples of the dicarboxylic acid compounds forming the thermoplastic polyester resin (A) used herein include known dicarboxylic acid compounds such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethanedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid and sebacic acid, and alkyl-, alkoxy- or halogen-substituted products thereof. These dicarboxylic acid compounds can be used in polymerization as ester-formable derivatives, for example, in the form of esters of lower alcohol such as dimethyl esters. Secondly, examples of the dihydroxy compounds forming the thermoplastic polyester resin (A) include dihydroxy compounds and polyoxyalkylene glycols such as ethylene glycol, propylene glycol, butanediol, neopentylglycol, hydroquinone, resorcin, dihydroxyphenyl, naphthalenediol, dihydroxyphenyl ether, cyclohexanediol, 2,2-bis(4-hydroxyphenyl)propane and diethoxybisphenol A, and alkyl-, alkoxy- or halogen-substituted products thereof. These compounds can be used singly or in admixture with two or more thereof. Examples of the oxycarboxylic acid compounds include oxycarboxylic acids such as oxybenzoic acid, oxynaphthoic acid and diphenyleneoxycarboxylic acid, and alkyl-, alkoxy- or halogen-substituted products thereof. Ester-formable derivatives of these compounds also can be used herein. In the present invention, these compounds are used singly or in admixture with two or more thereof. Polyesters having a branched or crosslinked structure that is used with a small amount of a trifunctional monomer such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol and trimethylolpropane also can be cited in addition to these polyesters. In the present invention, any thermoplastic polyester prepared from the aforesaid compounds as monomer components through polycondensation can be used as the component (A) of the present invention. These polyesters are used singly or in admixture with two or more thereof. Among them, polyalkylene terephthalates are preferably used, and polybutylene terephthalates and copolymers principally containing them are more preferably used. In the present invention, the thermoplastic polyesters can be modified by the methods such as a known crosslinking or graft polymerization. of these thermoplastic polyesters, the polybutylene terephthalate resin has a particularly high resistance against alkaline solutions.
Furthermore, the polybutylene terephthalate used in the present invention shows satisfactory resistance against alkaline solutions particularly when the concentration of a carboxyl end group is preferably 50 meq/kg or less, and more preferably 35 meq/kg or less. In order to meas

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