Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-05-09
2002-08-27
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S128000, C524S506000
Reexamination Certificate
active
06441069
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a styrenic resin composition and a molding product formed of the same. More specifically, it relates to a flame-retardant styrenic resin composition having a high flame retardance without using an organic halogen compound and excellent in mechanical properties, impact resistance and moldability, and a molding product formed of the same.
2. Description of the Related Art
Styrenic resins typified by rubber-reinforced styrenic resins are excellent in mechanical properties, moldability and electric insulation properties, and therefore find wide acceptance in various fields of parts of home electric appliances, office automation equipment and automobiles.
However, since styrenic resins are inherently flammable, various techniques of imparting a flame retardance have been so far proposed in view of safety.
As a technique of imparting a flame retardance to styrenic resins, a method in which a halogen-based flame retarder having a high efficiency of a flame retardance, such as abromine compound, and antimony oxide are incorporated into a resin to impart a frame retardance has been generally employed. A flame-retardant resin composition obtained by this method involves, however, a problem of a large fuming amount in combustion.
Thus, in order to overcome the defect of the halogen-based flame retarder, a completely halogen-free flame-retardant resin has been in high demand in recent years.
As a halogen-free flame retarder, there is a phosphorus-based flame retarder, and a phosphate ester has been so far used well as a typical one. For example, a method in which a polyphosphate is added to a styrenic resin (Japanese Patent Laid-Open No. 24,736/1984), a method in which a phosphate ester having a specific structure is added to a rubber-reinforced styrene (Japanese Patent Laid-Open No. 140,270/1999) and a method in which a liquid phosphate ester is added to a styrenic resin (Japanese Patent Laid-Open No. 5,869/1999) have been already disclosed.
However, since styrenic resins are extremely flammable, the effect of imparting a flame retardance is quite low with a phosphate ester. In the compositions obtained by the methods described in Japanese Patent Laid-Open Nos. 24,736/1984, 140,270/1999 and 5,869/1999, a large amount of a phosphate ester has to be added to styrenic resins for imparting the flame retardance thereto. Consequently, not only are mechanical properties decreased, but also there are problems that a phosphate ester is bled out, contamination of a mold occurs in the molding and a gas is generated in the molding.
In order to solve these problems, a method of using a hydroxyl group-having phosphate ester is disclosed in Japanese Patent Laid-Open No. 247,315/1993.
Nevertheless, the hydroxyl group-having phosphate ester has also quite a low effect of imparting a flame retardance. Thus, it has been difficult to solve the problems.
Since an effect of imparting a flame retardance is low with a phosphate ester, it was found that the flame retardance is improved by using melamine cyanurate as a flame-retardant aid in addition to a phosphate ester. However, this could not solve the problem that mechanical properties, an impact resistance and a moldability inherent in styrenic resins are impaired.
Besides, a method in which a phenolic novolak resin and further a compound having a triazine structure are added as a char layer forming polymer to a hydroxyl group-having phosphate ester for improving a flame retardance is disclosed in Japanese Patent Laid-Open No. 70,448/1995.
This technique cannot solve either the problem that mechanical properties, an impact resistance and a moldability inherent in styrenic resins are impaired. Moreover, since a phenolic resin is a material having quite a poor light resistance, there is a problem that a light resistance of the resulting resin composition is decreased.
A method in which red phosphorus having a high effect of imparting a flame retardance is used as a halogen-free flame retarder and a phenolic resin having a char layer formability is added as a flame-retardant aid is disclosed in Japanese Patent Laid-Open No. 157,866/1994.
Although a flame retardance can be imparted by this technique, mechanical properties, an impact resistance and a moldability inherent in styrenic resins are impaired. In addition, there is a problem that a molding product is colored in red phosphorus tint owing to red phosphorus.
Meanwhile, as a technique of using a phosphite ester having a similar structure to a phosphate ester, a method in which a halogen-based retarder and a phosphate ester are added to a styrenic resin for improving a heat stability (Japanese Patent Laid-Open No. 80,159/1974), a method in which a phosphite ester is added to ABS having a high content of acrylonitrile which tends to yellow for preventing coloration (Japanese Patent Laid-Open No. 94,548/1979), a method in which a phosphite ester having a molecular weight of 1,500 or more is added to modified PPE and a styrenic alloy for preventing coloration (Japanese Patent Laid-Open No. 174,439/1983) and a method in which a specific halogen-having compound and a phosphite ester are added to a styrenic resin for improving a heat stability (Japanese Patent Laid-Open No. 88,050/1992) have been already proposed. These techniques are, however, for improving a heat stability or preventing coloration and not for imparting a flame retardance.
When a phosphite ester was used as a flame retarder in a styrenic resin, a property of preventing coloration or a heat stability of a resin composition was indeed improved, but a flame retardance was rather decreased by incorporating the same into a flammable styrenic resin. Even though it was used in a large amount, a flame retardance was hardly imparted.
SUMMARY OF THE INVENTION
The invention aims to provide a flame-retardant resin composition having a high flame retardance and excellent in mechanical properties, impact resistance and moldability.
The construction of the invention is as follows.
A flame-retardant resin composition of the invention comprises (A) 100 parts by weight of a styrenic resin, (B) 1 to 30 parts by weight of one or more of phosphate ester compounds represented by the following formula (1), and (C) 0.1 to 10 parts by weight of one or more of phosphate ester compounds having a structure represented by the following formula (2) and having a long-chain alkyl group having 9 or more continuous carbon atoms in a molecule,
wherein
R
1
to R
8
, which may be the same or different, each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,
Y
1
represents a direct bond, O , S, SO
2
, C(CH
3
)
2
, CH
2
or CHPh in which Ph represents a phenyl group, Ar
1
to Ar
4
, which may be the same or different, each represent a phenyl group or a phenyl group substituted with a halogen-free organic residue,
n is an integer of at least 0, and
k and m are each an integer of at least 0 and at most 2, provided k+m is at least 0 and at most 2.
Further, a molding product of the invention is formed by molding the flame-retardant resin composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The flame-retardant resin composition and the molding product formed of the same in the invention are specifically described below.
The styrenic resin (A) used in the invention is a polymer polymerizing a monomer or a monomer mixture containing an aromatic vinyl monomer as a main constituting component. Examples of this aromatic vinyl monomer include styrene, &agr;-methylstyrene, p-methylstyrene, vinyl toluene, tert-butylstyrene and o-ethylstyrene. Especially, styrene and &agr;-methylstyrene are preferably used. These may be used either singly or in combination.
For imparting properties such as a chemical resistance and a heat resistance to the styrenic resin, another vinyl monomer copolymerizable with the aromatic vinyl monomer may be copolymerized. Examples of another vinyl monomer include acrylonitrile, methacrylonitrile, ethacrylonitrile, (meth)acrylic acid, methyl (meth)acrylate, eth
Honma Masato
Tamai Akiyoshi
Tamura Shinichi
Rajguru U. K
Schnader Harrison Segal & Lewis LLP
Seidleck James J.
Toray Industries Inc.
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