Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-12-08
2002-05-07
Medley, Margaret (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S145000, C524S174000, C524S087000
Reexamination Certificate
active
06384114
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flame-retardant thermoplastic resin composition, more precisely, to a flame-retardant thermoplastic resin composition and its moldings having the advantages of good impact resistance, good oil resistance, good heat stability and good recyclability. The invention also relates to a flame-retardant polycarbonate resin composition, in particular to that having good moldability and good heat stability and therefore suitable to injection molding to give thin-walled or large-sized moldings, and relates to moldings of the resin composition as produced by molding the resin composition through injection molding. Favorably, the polycarbonate resin composition is molded through injection molding in hot runner molds to give moldings having good outward appearances.
2. Description of the Related Art
As having the advantages of impact resistance, heat resistance and good electric properties, polycarbonate resins have many applications in various fields of, for example, office automation appliances, electric and electronic appliances, car parts and building materials. However, there are some problems with polycarbonate resins in that they require high molding and working temperatures and their melt fluidity is low. Therefore, they require relatively high molding temperatures. In particular, when various additives are added thereto, their thermal stability is often lowered, and, in addition, they could not often exhibit their good properties.
As a rule, polycarbonate resins are self-extinguishable. However, some of their applications to office automation appliances, electric and electronic appliances and others require high-level flame retardancy. To meet the requirement, various flame retardants are added to polycarbonate resins.
On the other hand, moldings for parts and housings for office automation appliances such as duplicators and facsimiles and for other electric and electronic appliances such as those mentioned above shall have a complicated shape with local projections or depressions, for example, having ribs or bosses therewith, and are required to be lightweight and thin-walled from the viewpoint of resources saving. Therefore, desired are polycarbonate resin compositions having increased melt fluidity, or that is, having increased injection moldability.
On the other hand, compositions of polycarbonate resins to which are added styrene resins such as acrylonitrile-butadiene-styrene resins (ABS resins), a rubber-modified styrenic resin (HIPS), acrylonitrile-styrene resins (AS resins) and the like are known as polymer alloys, and have many applications in the field of moldings as having good heat resistance and impact resistance.
For improving the flame retardancy of polycarbonate resins, halogen—containing flame retardants such as bisphenol A halides and halogenated polycarbonate oligomers have been used along with a flame retardation promoter such as antimony oxide, as their flame-retarding ability is good. However, with the recent tendency toward safety living and environmental protection, the market requires flame retardation with non-halogen flame retardants. As non-halogen flame retardants, phosphorus—containing organic flame retardants, especially organic phosphate ester compounds may be added to polycarbonate resin compositions, for which various methods have been proposed. Such flame retardants, organic phosphate ester compounds serve also as a plasticizer, and polycarbonate resin compositions containing them exhibit excellent flame retardancy.
To meet the requirements as above, various methods have heretofore been proposed. Concretely, JP-A 61-55145 discloses a thermoplastic resin composition comprising (A) an aromatic polycarbonateresin, (B) an ABS resin, (C) an AS resin, (D) a halogen compound, (E) a phosphate, and (F) a polytetrafluoroethylene component. JP-A 2-32154 discloses a molding polycarbonate composition with high flame retardancy and high impact resistance, comprising (A) an aromatic polycarbonate resin, (B) an ABS resin, (C) an AS resin, (D) a phosphate, and (E) a polytetrafluoroethylene component. JP-A 8-239565 discloses a polycarbonate resin composition comprising (A) an aromatic polycarbonate, (B) an impact-resistant polystyrene resin with rubber-like elasticity, (C) a halogen-free phosphate, (D) a core/shell-type grafted rubber-like elastomer, and (E) talc.
These are all to improve the melt fluidity and therefore the moldability of polycarbonates, and to improve the impact resistance and the flame retardancy of the moldings of polycarbonates. As having such improved properties, the polycarbonate compositions proposed are formed into various practicable moldings.
However, in order to make the compositions comprising a polycarbonate resin and a (rubber-modified) styrenic resin and having good melt fluidity have good flame retardancy by adding thereto a phosphate ester compound, a relatively large amount of the compound must be added to the compositions. Though their flame-retarding ability is good, phosphate ester compounds often cause some problems when added to resin compositions. For example, it is said that phosphate ester compounds will corrode molds used for molding resin compositions containing them, and, in addition, the compounds will lower the impact strength of resin moldings or will yellow them in high-temperature conditions or in high-humidity conditions.
On the other hand, phosphate ester compounds serve not only as a flame retardant but also as a plasticizer for resin compositions, and they could improve the melt moldability, especially the injection moldability of resin compositions containing them. Therefore, phosphate ester compounds could be excellent additives to resin compositions for improving the properties of resin compositions containing them, but are said to be confronted with some problems. For example, polycarbonate or styrenic resin compositions containing phosphate ester compounds could have good melt moldability, especially good injection moldability, but their moldings often have poor heat stability, depending on their shape and on the molds used for producing them. In particular, when the resin compositions are molded in injection molds such as hot runner molds where resin melts being molded therein reside for a while, the resulting moldings will be often yellowed or will have silver marks on their surface. Therefore, it is difficult to stably mold the resin compositions into moldings having good appearances, and some failed moldings will be inevitable. For these reasons, adding phosphate ester compounds to resin compositions is not all the time satisfactory. Moreover, the long-term stability of the resin moldings in high-temperature condition is often poor.
In addition, depending on their type, phosphate ester compounds often bloom resin moldings. To overcome this problem, proposed is using phosphate ester compounds having a high melting point. For this, also proposed is a method of specifically defining the monomer content and the impurity content of resins to be molded. However, polycarbonate resins for molding materials generally require relatively high molding temperatures, and merely selecting the type of phosphate ester compounds for them could not satisfactorily solve the problem of low heat stability of the resin moldings. These days, in particular, hot runner molds for injection molding are much used for producing thin-walled, complicated and large-sized resin moldings, and the resin moldings to be produced in such molds through injection moldings are required to have further higher heat stability.
To meet the requirement, proposed is using high-viscosity, high-melting point phosphate ester compounds, or using different types of phosphate ester compounds as combined. In this connection, for example, known are various methods such as those described in Japanese Patent Laid-Open Nos. 228426/1994, 151493/1996, 225737/1996, 337712/1996, 95610/1997 and 249768/1997. In these laid-open patent specifications, they say that not only using
Idemitsu Petrochemical Co. Ltd.
Medley Margaret
Oblon, Spivak, McClelland, Maier & Nuestadt, P.C.
LandOfFree
Flame-retardant polycarbonate resin composition and its... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flame-retardant polycarbonate resin composition and its..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flame-retardant polycarbonate resin composition and its... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2904170