Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-07-30
2004-03-02
Wilson, Donald R. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S381000, C525S382000, C525S374000, C525S209000, C525S228000
Reexamination Certificate
active
06699944
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an acrylic rubber composition. More particularly, it relates to an acrylic rubber composition comprising an acrylic polymer having an active halogen serving as a crosslinking group and a crosslinking agent.
BACKGROUND ART
Halogen-containing acrylic rubbers are synthesized by copolymerization of an alkyl acrylate and/or an alkoxyalkyl acrylate as the main component and an active halogen-containing monomer as a crosslinking component. And, the crosslinking products are used as rubbers showing good oil resistance, heat resistance, weathering resistance, ozone resistance and permanent compression set, hence as sealing materials, inclusive of packings and gaskets, and as various molded products.
The conventional halogen-containing acrylic rubbers are produced by the so-called free radical polymerization, such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, bulk-suspension polymerization, using a polymerization initiator. Since they are produced by the free radical polymerization method, an active halogen-containing monomer to serve as a crosslinking site is introduced into the molecular chain substantially at random and, therefore, for obtaining low-modulus, high-elongation rubbers while securing crosslinking sites, one cannot but increase the molecular weight. Thus, in incorporating various compounding additives in acrylic rubbers showing a high viscosity because of their high molecular weight, the compounding must be carried out using an open roll or kneader and spending time and energy. Accordingly, they cannot be said to be easy to handle. In the current state of art, it is very difficult to decrease the molecular weight to thereby reduce the viscosity and improve the handleability.
In the above situation, the present inventors found that an acrylic rubber composition showing good handleability can be obtained by crosslinking an acrylic polymer having an active halogen represented by the following general formula (1) at a main chain terminus using a crosslinking agent. Based on this finding, they have now completed the present invention.
SUMMARY OF THE INVENTION
Thus, the invention is related to an acrylic rubber composition which comprises the following two components:
(A) an acrylic polymer having at least one active halogen represented by the general formula (1) at a main chain terminus:
—CH
2
—C(R
1
)(R
2
)(X) (1)
wherein R
1
and R
2
are the same or different and each represents a hydrogen atom or univalent organic group derived from a group bonded to a vinyl group of a main chain-constituting vinyl monomer and X represents chlorine, bromine or iodine; and
(B) a crosslinking agent.
DETAILED DISCLOSURE OF THE INVENTION
In the following, the acrylic rubber composition of the present invention is described in detail.
[Re: (A) Component Acrylic Polymer]
The acrylic polymer having at least one active halogen represented by the general formula (1) at a main chain terminus according to the present invention is obtained by (co)polymerizing at least one vinyl monomer such as an alkyl acrylate and/or an alkoxyalkyl acrylate, preferably by atom transfer radical polymerization.
—CH
2
—C(R
1
)(R
2
)(X) (1)
(In the formula, R
1
and R
2
are the same or different and each represents a hydrogen atom or univalent organic group derived from a group bonded to a vinyl group of a main chain-constituting vinyl monomer and X represents chlorine, bromine or iodine.)
The above-mentioned acrylic polymer having at least one active halogen represented by the general formula (1) at a main chain terminus reacts with the (B) component crosslinking agent to be thereby crosslinked and give a rubber-like cured product. When the number of the active halogen represented by the general formula (1) occurring in one molecule is less than 1 on an average, any satisfactory curing product can be obtained. For obtaining satisfactory curing products, the polymer should preferably have, on an average, 1.1 to 4, more preferably 1.2 to 2, active halogens represented by the general formula (1).
The (A) component acrylic polymer may be a homopolymer or a copolymer. When it is a homopolymer, it is obtained by using one kind selected from among alkyl acrylates and alkoxyalkyl acrylates. When it is a copolymer, it is obtained by copolymerizing two or more kinds selected from among alkyl acrylates and alkoxyalkyl acrylates or by copolymerizing one or more kinds selected from among alkyl acrylates and alkoxyalkyl acrylates with a monomer or monomers other than those.
In the present invention, the main chain-constituting vinyl monomer includes radical-polymerizable monomers having an ethylenically unsaturated bond, inclusive of alkyl acrylates, alkoxyalkyl acrylates and other monomers.
As the alkyl acrylate in the practice of the invention, there may be mentioned methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, stearyl acrylate and the like and, among them, ethyl acrylate and n-butyl acrylate are particularly preferred. These alkyl acrylates may be used singly or two or more of them may be used in combination.
As the alkoxyalkyl acrylate, there may be mentioned, for example, methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-propoxyethyl acrylate, 2-butoxyethyl acrylate, 3-methoxypropyl acrylate, 4-methoxybutyl (meth)acrylate and the like. In particular, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are preferred. These alkoxyalkyl acrylates may be used singly or two or more of them may be used in combination.
Further, as the vinyl monomer (hereinafter referred to as “other monomer”) other than such alkyl acrylate or alkoxyalkyl acrylate, there may be mentioned esters of halogen-containing saturated carboxylic acids with unsaturated alcohols, such as vinyl chloroacetate and allyl chloroacetate; haloalkyl (meth)acrylates such as chloromethyl (meth)acrylate and 2-chloroethyl (meth)acrylate; halogen-containing unsaturated ethers such as chloromethyl vinyl ether and 3-chloropropyl allyl ether; halogen-containing unsaturated ketones such as 2-chloroethyl vinyl ketone and 3-chloropropyl vinyl ketone; haloacyloxyalkyl (meth) acrylates such as 2-(chloroacetoxy)ethyl (meth)acrylate and 3-(chloroacetoxy)propyl (meth)acrylate; halomethyl-containing aromatic vinyl compounds such as p-chloromethylstyrene and p-chloromethyl-&agr;-methylstyrene; other vinyl monomers having an active halogen capable of participating in crosslinking reactions; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, cyclohexylmethacrylate, n-heptylmethacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, dodecyl methacrylate and stearyl methacrylate; (meth)acrylic monomers other than the alkyl acrylates, alkoxyalkyl acrylates and alkyl methacrylates, for example phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, &ggr;-(methacryloyloxy)propyltrimethoxysilane, (meth)acrylic acid-ethylene oxide adducts, trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate and (meth)acrylic acid; styrenic monomers s
Fujita Masayuki
Nakagawa Yoshiki
Connolly Bove & Lodge & Hutz LLP
Kaneka Corporation
Wilson Donald R.
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