Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-12-27
2004-05-11
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S117000
Reexamination Certificate
active
06734239
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flame retardant for resins containing as a main component a phosphoric ester having a phosphorinane structure, and a flame-retarded resin composition containing the ester.
2. Description of Background Information
Thermoplastic resins such as polypropylene, polystyrene or acrylonitrile-butadiene-styrene (ABS) resin, etc. and thermosetting resins such as polyurethane or phenolic resin, etc. can be produced at relatively low costs and have excellent characteristics such as capability of being easily molded. For this reason, these resins are generally used for a wide variety of everyday articles including electronic components and automobile components.
Since the resins themselves are easy to flame, the resins easily burn out once the resins catch fire. Fires especially at public facilities such as electric or communications cables may have serious effects on social functions. Today, flame-retardation is legally demanded with regard to some fields where resins are used such as fields of electric appliances, automobile interiors, textile products, etc. As such flame-retardation regulations, are known the UL standards for electric appliances in the United State, FMVSS-302 regarding automobiles and the like.
In order to provide flame retardant properties to resins, the process of adding flame retardants for resins (referred to as flame retardants hereinafter) during preparation of resin compositions for molding is generally adopted. Such flame retardants include inorganic compounds, organic phosphorus compounds, organic halogen compounds, halogen-containing organic phosphorus compounds and the like.
Of the above-mentioned compounds, the organic halogen compounds and halogen-containing organic phosphorus compounds exhibit an excellent flame retardant effect. However, these compounds containing halogen generate hydrogen halide by thermal decomposition during the molding of resins. That will cause problems such as corrosion of mold dies, deterioration of resins and coloring of resins. Further, hydrogen halide worsens work environment because of its toxicity. In addition to that, the halogen-containing compounds adversely affect human bodies by generating toxic gases such as hydrogen halide and dioxins during burning, for example, in fires.
It is generally considered that coloring which takes place in the molding of resins is caused by phosphoric acid or hydrogen chloride generated by dehalogenation reaction and an amine-hydrochloride generated in the co-presence of an amine.
Flame retardants not containing halogens include inorganic compounds such as magnesium hydroxide, aluminum hydroxide, calcium hydroxide, etc. However, these inorganic compounds have only significantly poor flame retardant effects. Consequently, it is necessary to add these compounds in a large amount for obtaining a sufficient flame retardant effect. Thereby, intrinsic properties of resins, especially mechanical properties of molded articles of resins may be impaired.
Therefore, is strongly demanded the development of a flame retardant which does not contain any halogen and is free of the above-described drawbacks.
U.S. Pat. No. 5,750,601 discloses 5,5-dimethyl-2-oxo-2-phenoxy-1,3,2-dioxaphosphorinane as a flame retardant not containing a halogen.
However, this compound is solid within the range of room temperature to temperatures at which resins are molded. Therefore, it is difficult to mix the compound with resin materials or to disperse the compound uniformly into the resin materials. For example, a polyurethane foam is obtained by condensation reaction of a diisocyanate with a polyol in which a solid flame retardant is dispersed beforehand. A problem lies in that the flame retardant settles and does not uniformly disperse in the polyol. Also, since the flame retardant is solid, it is difficult to add the flame retardant in a constant amount automatically and handle the flame retardant when the flame retardant is added to a resin material during the preparation of a resin composition for molding.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is to solve the drawbacks of the prior-art techniques as described above, and an object of the present invention is to provide a flame retardant not containing a halogen which, when added to various kinds of resins, gives excellent flame retardancy to the resins without declining the intrinsic properties of the resins and which has a good resistance to hydrolysis, and a flame-retarded resin composition having excellent mechanical properties.
As a result of intensive study to solve the above problems, the inventors have found the blending of a specific phosphoric ester with a resin, and have accomplished the present invention.
Of the phosphoric esters represented by the formula (I) of the present invention, a compound having methyl groups as R
1
and R
2
and a methyl group as R
3
is known, for example, as a lubricating oil component, but has been found to have an unexpectedly excellent effect when used as a flame retardant.
Accordingly, the present invention provides a flame retardant for resins containing a phosphoric ester (referred to as “phosphoric ester (I)” hereinafter) represented by the formula (I):
wherein R
1
and R
2
, the same or different, are an alkyl group having a carbon number of 1 to 6 and R
3
is an alkyl group having a carbon number of 1 to 20.
Also, according to the present invention, there is provided a flame-retarded resin composition (referred to as “a resin composition” hereinafter) containing the above-mentioned flame retardant as a flame retardant in a resin.
DETAILED DESCRIPTION OF THE INVENTION
The phosphoric ester contained in the flame retardant of the present invention is represented by the aforesaid formula (I).
In the formula (I), as alkyl groups of R
1
and R
2
having a carbon number of 1 to 6, straight-chain or branched alkyl groups may be mentioned, examples of which include straight-chain alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, etc., and branched alkyl groups such as iso-propyl, iso-butyl, sec-butyl, tert-butyl, iso-pentyl, tert-pentyl, neo-pentyl, iso-hexyl, etc. Among these groups, straight-chain or branched alkyl groups having a carbon number of 1 to 4 are preferable, and methyl is the most preferable.
As alkyl groups of R
3
having a carbon number of 1 to 20, straight-chain or branched alkyl groups may be mentioned, among which alkyl groups having a carbon number of 1 to 18 are preferable. Examples thereof include straight-chain alkyl groups such as n-heptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, etc., and branched alkyl groups such as methylhexyl, methylheptyl, 2-ethylhexyl, iso-decyl, iso-dodecyl, iso-tetradecyl, iso-hexadecyl, iso-octadecyl, etc., as well as the alkyl groups mentioned above as examples of R
1
and R
2
. Among these groups, straight-chain or branched lower alkyl groups having a carbon number of 1 to 4 are preferable, and n-propyl and n-butyl are the most preferable.
Phosphoric esters (I) wherein R
3
is a lower alkyl group are liquid at ordinary temperature and have a low viscosity (15 to 40 cps/25° C.). They have suitable properties for flame retardants.
As examples of the phosphoric esters (I), the compounds described in Production Examples 1 and 2 may be mentioned.
The phosphoric esters (I) of the present invention might contain impurities derived from by-products and unreacted materials during production, but may be used as flame retardants without being further purified so long as the impurities do not affect the thermal resistance and the flame retardancy of resin compositions.
The flame retardant of the present invention may be a mixture of two or more species of phosphoric esters (I).
The resin composition of the present invention contains a resin and the above-described flame retardant.
As examples of the resin, may be mentioned thermoplastic resins such as chlorinated polyethylene, polyethylene, polypropylene, polybutadiene, styren
Kameda Katumi
Tokuyasu Noriaki
Daihachi Chemical Industry Co. Ltd.
Greenblum & Bernstein P.L.C.
Szekely Peter
LandOfFree
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