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
2002-08-14
2003-11-04
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C528S018000, C528S021000, C528S023000
Reexamination Certificate
active
06642309
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a curable resin composition. The object of the invention is to provide a novel acrylic-modified silyl-terminated polyether resin outstanding in fast-curability, storage stability, weatherability, and adhesiveness.
BACKGROUND OF THE INVENTION
Room temperature-curable resin compositions based on a oxyalkylene polymer having at least one reactive silyl group (a silicon-containing group having an silicon atom attached to a hydroxyl or hydrolyzable group and being capable of forming a siloxane bond), particularly methyldimethoxysilyl, can be used as architectural sealants, adhesives, and other artifacts and promise good performances at low cost. Furthermore, the so-called acrylic-modified silyl-terminated polyether resin composition representing a formulation of a reactive silyl group-containing acrylic copolymer with said oxyalkylene polymer is also available commercially and in broad use as the base polymer for high weather-resistant sealants or the base polymer for room temperature-curable adhesives used as one package system.
The acrylic-modified silyl-terminated polyether resin composition referred to above has characteristics distinct from said methyldimethoxysilyl group-containing oxyalkylene polymer, i.e. greater initial tack, firmer adhesiveness to various adherends, and better weatherability, and is in broad use as an adhesive or sealant having an excellent bonding function and a good storage stability. However, it is reported that this composition has some technical drawbacks to be overcome in the aspects of internal curability and cure rate (Japanese Kokai Publication Hei-10-251552).
Referring to the reactive silyl functional group of said acrylic copolymer, the use of a copolymer containing trimethoxysilyl group is proposed in Japanese Kokai Publication Hei-01-236258, for instance. However, in the case of this copolymer, it is not only difficult to control the pot life because of the dramatic increase in cure rate but the adhesiveness to certain adherends such as polycarbonate tend to be poor.
Furthermore, the use of trimethoxysilyl as the reactive silyl functional group of oxypropylene polymers reportedly provides for good internal curability and a characteristically very high cure rate. However, in this case it is not only difficult to control the pot life and assure sufficient storage stability but the adhesive function attainable is inferior to the commercial methyldimethoxysilyl-containing oxypropylene polymers, thus being of no industrial value and, hence, having not been launched onto the market.
Japanese Kokai Publication Hei-10-251552 proposes, as an acrylic-modified silyl-terminated polyether composition having good storage stability, good internal curability, very fast cure rate and good adhesive function, an acrylic-modified silyl-terminated polyether resin composition whose resin component comprises (A) an oxypropylene polymer having a main chain substantially consisting of oxypropylene units and containing trimethoxysilyl as the reactive silyl functional group, (B) an oxypropylene polymer having a main chain substantially consisting of oxypropylene units and containing methyldimethoxysilyl group as the reactive silyl functional group, and (C) an acrylic copolymer containing a reactive silyl group which is obtainable by polymerizing, as a main component, at least one monomer selected from the group consisting of acrylic esters and methacrylic esters containing an alkoxysilyl group within the molecule and having an alkyl group containing 1 to 20 carbon atoms.
However, this technology has the drawback that two kinds of oxypropylene polymers having dissimilar reactive silyl functional groups and, further, an acrylic polymer having silyl functional group must be independently produced and handled. In particular, the trimethoxysilyl group-containing polyoxypropylene has not been commercially available as yet so that the technology appears to be unsatisfactory in terms of availability of raw material, aspect of synthetic reaction, storage stability and so on.
An acrylic-modified silyl-terminated polyether resin composition which is advantageous not only in terms of the availability of raw materials and the ease of synthetic reaction, but also in fast-curing, good storage stability, good weatherability, high adhesiveness, and further is benign on the environment, which is a major social consideration in recent years, if provided, should be of great industrial value.
OBJECT OF THE INVENTION
The object of the present invention is to provide a novel acrylic-modified silyl-terminated polyether resin composition which is advantageous not only in terms of the availability of raw materials and the ease of synthetic reaction, but also in fast-curing, good storage stability, good weatherability, high adhesiveness, thus promising high potentials of industrial utilization. Further, the object of the present invention is also to develop an environment-friendly curable composition which is a major social consideration.
SUMMARY OF THE INVENTION
As the result of their intensive research, the inventors of the present invention discovered that, in the art of curable compositions comprising an oxyalkylene polymer (A) having silyl functional group and a copolymer (B) having a silyl functional group and a molecular chain comprising alkyl acrylate and/or alkyl methacrylate monomer units, the use of a curable composition containing said copolymer (B) having both dialkoxysilyl and trialkoxysilyl groups as the silyl functional group results in a high cure rate without being compromised in the good adhesiveness, high weatherability and good storage stability of the conventional acrylic-modified silyl-terminated polyether resin composition.
It was also found that the acrylic-modified silyl-terminated polyether resin composition of the invention permits not only the use of the conventional organotin catalyst but also the use of those cure-accelerating catalysts other than organotin compounds with which a practically useful cure rate could not be obtained in the past.
The present invention, therefore, is related to a curable composition comprising an oxyalkylene polymer (A) containing silyl functional group capable of crosslinking by forming a siloxane bond and a copolymer (B) having a molecular chain comprising alkyl acrylate and/or alkyl methacrylate monomer units and containing silyl functional group capable of crosslinking by forming a siloxane bond,
said copolymer (B) having both dialkoxysilyl and trialkoxysilyl groups as said silyl functional group.
Furthermore, the above-mentioned copolymer (B) has both dialkoxysilyl and trialkoxysilyl groups within the molecule and/or is a mixture of a copolymer having dialkoxysilyl functional group and a copolymer having trialkoxysilyl functional group.
The present invention is further related to an acrylic-modified silyl-terminated polyether curable composition
which comprises said polymer (A) contains at least one dimethoxysilyl group per molecule and has a number average molecular weight of not less than 6,000,
while said copolymer (B) contains at least an average of 0.2 trimethoxysilyl groups and at least an average of 0.2 dimethoxysilyl groups per molecule, and
which comprises further contains a cure accelerating catalyst (C).
Furthermore, in accordance with the invention, a substantially useful cure rate can be obtained even with a non-organotin catalyst, for example an organic carboxylic acid, an organic carboxylic acid metal salt, an amine compound, an acid phosphate ester or a Group 3B or Group 4A metal as said (C) cure accelerating catalyst.
According to the present invention, an acrylic-modified silyl-terminated polyether curable composition not only showing an improved cure rate but also exhibiting good adhesiveness and storage stability can be obtained.
DETAILED DESCRIPTION OF THE INVENTION
As the oxyalkylene polymer constituting the main chain of the (A) component polymer according to the invention, the polymer which can be represented by the following general formula can be use
Iwakiri Hiroshi
Komitsu Shintaro
Okamoto Toshihiko
Kaneka Corporation
Moore Margaret G.
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