Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-09-15
2001-10-16
Hoke, Veronica P. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S437000, C174S11000P
Reexamination Certificate
active
06303681
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to a flame-retardant polyolefin-type resin composition, to a method for the preparation thereof, and to flame-retardant cables coated with the composition. More particularly, this invention relates to a highly flame-retardant, highly moldable flame-retardant polyolefin-type resin composition that exhibits excellent mechanical strength, to a method for the preparation of same, and to flame-retardant cables having a coating of the aforesaid flame-retardant polyolefin-type resin composition
One method used to impart flame retardancy to polyolefin-type resins, e.g., polyethylene resins and ethylene-vinyl acetate copolymer resins, comprises blending polyolefin-type resin with a halogen-containing compound (chlorine is a typical example of the halogen). However, halogenated compound-loaded polyolefin-type resin compositions of this type, in addition to evolving large amounts of black smoke during burning, produce gases harmful to humans and corrosive to metals. The addition of the powder of a hydrated metal compound, such as aluminum hydroxide powder or magnesium hydroxide powder, to polyolefin-type resin has already been proposed in order to address the problems described above for halogenated compounds. Unfortunately, this approach has required the addition of large amounts of the hydrated metal compound powder in order to impart flame retardancy to the polyolefin-type resin, and this high loading requirement has prevented the production of anything other than flame-retardant polyolefin-type resins with poor moldabilities and diminished mechanical strength. Japanese Laid Open Patent Application Number Hei 5-339510 (339,510/1993) teaches the production of flame-retardant polyolefin-type resin compositions by the addition of alkoxy-functional branched organosiloxane resin, phosphate ester, and metal hydroxide to thermoplastic resins such as styrenic resins and polyolefin-type resins. One problem with this method is that it affords a flame-retardant polyolefin-type resin composition whose flame retardancy is not entirely satisfactory. Moreover, because it requires the use of phosphate ester, this method, for example, may be unacceptable depending on the particular application and, within the context of disposal, because of the concern of soil pollution by phosphorus compounds.
The inventors achieved this invention as a result of intensive investigations directed to solving the problems described above. In specific terms, an object of this invention is to provide a highly moldable and flame-retardant polyolefin-type resin composition. Additional objects of this invention are to provide a method for producing this flame-retardant polyolefin-type resin composition and to provide flame-retardant cables.
SUMMARY OF INVENTION
The present invention is a flame-retardant polyolefin-type resin composition comprising
(A) 100 weight parts polyolefin-type resin,
(B) 30 to 200 weight parts powder of a hydrated metal compound, and
(C) 0.01 to 50 weight parts branched organopolysiloxane with average unit formula
R
a
SiO
(4−a)/2
where each R is a selected from the group consisting of monovalent organic groups selected from the group consisting of C
1
to C
12
alkyl and C
6
to C
12
aryl and hydroxyl, wherein aryl constitutes from 50 to 100 mole % of the total monovalent organic groups and the hydroxyl content in each molecule is from 1 to 10 weight %, a is a number from 0.75 to 2.5, and the organopolysiloxane contains at least one RSiO
3/2
siloxane unit in each molecule, where R is as previously described.
The invention additionally relates to a method for producing the flame-retardant polyolefin-type resin composition and to flame-retardant cables having a coating of the flame-retardant polyolefin-type resin composition.
DESCRIPTION OF INVENTION
The present invention is a flame-retardant polyolefin-type resin composition comprising
(A) 100 weight parts polyolefin-type resin,
(B) 30 to 200 weight parts powder of a hydrated metal compound, and
(C) 0.01 to 50 weight parts branched organopolysiloxane with average unit formula
R
a
SiO
(4−a)/2
where each R is a selected from the group consisting of monovalent organic groups selected from the group consisting of C
1
to C
12
alkyl and C
6
to C
12
aryl and hydroxyl, wherein aryl constitutes from 50 to 100 mole % of the total monovalent organic groups and the hydroxyl content in each molecule is from 1 to 10 weight %, a is a number from 0.75 to 2.5, and the organopolysiloxane contains at least one RSiO
3/2
siloxane unit in each molecule, where R is as previously described.
The invention additionally relates to a method for producing the flame-retardant polyolefin-type resin composition and to flame-retardant cables having a coating of the flame-retardant polyolefin-type resin composition.
The polyolefin-type resin (A) used in this invention as a general matter encompasses those high molecular weight compounds known as polyolefin-type resins, that is, the high molecular weight polymers whose main backbone derives from ethylene-series hydrocarbon. Such features as the specific type and so forth are not critical. The polyolefin-type resin under consideration can be exemplified by polyethylenes such as high-density polyethylene, medium-density polyethylene, and low-density polyethylene; copolymers of ethylene with C
3
to C
12
&agr;-olefin such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene; polypropylenes; copolymers of propylene with C
2
to C
12
&agr;-olefin such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1 decene; ethylene-propylene copolymer rubbers; ethylene-propylene-iene copolymer rubbers; the copolymers of ethylene with vinylic monomer such as vinyl acetate, ethyl acrylate, methacrylic acid, ethyl methacrylate, maleic acid, and maleic anhydride; the copolymers afforded by the modification of polyethylene or an ethylene &agr;-olefin copolymer with an unsaturated carboxylic acid, such as acrylic acid and maleic acid, or derivative of an unsaturated carboxylic acid; and mixtures of the preceding polyolefin-type resins. Preferred among these examples are the polyethylenes, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, and copolymers of maleic acid or maleic anhydride with ethylene or &agr;-olefin.
The hydrated metal compound powder (B) used in this invention is the essential component for imparting flame retardancy to the composition. Component (B) with a decomposition initiation temperature in the range of from 150 to 450° C. is preferred because such a component (B) has a high flame-retarding activity. Component (B) also preferably has an average particle size in the range from 0.01 to 30 &mgr;m for the good dispersibility in polyolefin-type resins this affords. An average particle size in the range from 0.05 to 10 &mgr;m is even more preferred. Component (B) can be exemplified by magnesium hydroxide powder, aluminum hydroxide powder, and these powders after surface treatment with a surface treatment agent such as a silane coupling agent, titanium coupling agent, or higher aliphatic acid. Magnesium hydroxide is the preferred selection from among the preceding.
Component (B) should be introduced into the present composition at from 30 to 200 weight parts per 100 weight parts component (A) and is preferably introduced at from 50 to 150 weight parts per 100 weight parts component (A). An inability to impart a desirable flame retardancy to the polyolefin-type resin composition can occur when the addition of component (B) falls below 30 weight parts, while additions in excess of 200 weight parts cause the polyolefin-type resin composition to have a reduced mechanical strength.
The branched organopolysiloxane (C) used in the present composition is the component that characterizes this invention. Component (C) functions, in its co-use with component (B), to improve the flame retardancy of the composition of this invention. Component (C) also functions to improve the moldability of the present co
Furukawa Haruhiko
Hatanaka Hidekatsu
Morita Yoshitsugu
Nakanishi Koji
Shiromoto Koji
Dow Corning Toray Silicone Company, Ltd.
Hoke Veronica P.
Weitz Alex
Zombeck Alan
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