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
1999-10-21
2001-10-23
Dawson, Robert (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...
C525S404000, C528S901000, C524S493000
Reexamination Certificate
active
06306966
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a moisture curable composition suitable for use as an adhesive, a sealing material or the like which is required to be transparent.
2. Description of Related Art
Currently, a composition produced by normally blending an inorganic powder such as calcium carbonate or the like into a polymer having reactive silicon groups has been used in practice as an adhesive, a sealing material, or the like. The effect of blending the inorganic powder in this case is to give cohesive power to the polymer mainly having the reactive silicon groups, and to improve the adhesiveness on the interface with an adherend.
In recent years, when a transparent substrate such as glass, polycarbonate, acrylic resin or the like is adhered or sealed with an adhesive or a sealing material, the adhesive or the sealing material is also required to be transparent from the design viewpoint. However, there has been no transparent polymeric composition having reactive silicon groups which satisfies sufficient property of an adhesive or a sealing material.
In order to give the transparency to an adhesive and a sealing material, there are the following two methods: (1) a method without blending a filler; and (2) a method of blending an inorganic filler having a small grain diameter. However, the method (1) implies problems related to the basic properties such as the insufficient adhesiveness. The method (2) has problems that if a blended inorganic filler has a grain diameter of 0.01 &mgr;m or more, the resultant composition can not provide a sufficient transparency, and that if the grain diameter is smaller than 0.01 &mgr;m, it exhibits a viscosity which is abruptly increased with a small amount of the inorganic filler being added, a poor storage stability, and so on.
As a solvent-based adhesive which has excellent transparency without blending a filler, urethane adhesives, polyvinyl chloride adhesives and the like are placed on the market. However, when transparent adherends are adhered each other using the solvent-based adhesive, for its flowability there are formed starved areas due to air between the adherends and the adhesive, unless the adherends are adhered with a fair amount of solvent remaining therein. Such starved joints lead disadvantageously to opaque portions existing at adhering areas. The solvent included in the adhesive may also unfavorably dissolve plastics and bring about some cracks on adherends.
OBJECT AND SUMMARY OF THE INVENTION
The present inventors have devoted themselves to advance investigations so as to obtain a moisture curable composition of sufficient transparency which satisfies the basic properties of an adhesive and a sealing material, and consequently attained the present invention.
It is therefore an object of the present invention to provide a moisture curable composition which is excellent in transparency, operating efficiency and storage stability, and is suitable for use as an adhesive, a sealing material or the like.
To solve the above problem, a moisture curable composition according to the present invention is produced by blending 100 parts by weight of a mixture (A) comprising (1) a copolymer having reactive silicon groups which can be cross-linked by hydrolysis, whose molecular chain has (i) alkylacrylate and/or alkylmethacrylate monomeric units having an alkyl group with 1 to 8 carbon atoms, and (ii) alkylacrylate and/or alkylmethacrylate monomeric units having an alkyl group with 10 or more carbon atoms, and (2) an oxyalkylene polymer including reactive silicon groups which can be cross-linked by hydrolysis, and 2 parts by weight to 300 parts by weight of amorphous powder (B) having a grain diameter ranging from 0.01 &mgr;m to 300 &mgr;m.
DETAILED DESCRIPTION OF THE INVENTION
The reactive silicon group in the mixture (A) of the present invention represents a functional group including silicon which can form cross-linking through siloxane linkage. A preferred example of the reactive silicon group will be expressed by the following general formula (I):
where R
1
represents a substituted or unsubstituted monovalent organic group having 1 to 20 carbon atoms or a triorganosiloxy group; X represents a hydroxyl group or a heterogeneous or homogeneous hydrolyzable group; a is an integer of 0, 1 or 2; b is an integer of 0, 1, 2 or 3, provided that a is not 2 when b is 3; and m is an integer of 0 to 18.
The mixture (A) used in the present invention may include a polymer including silyl groups, or an acrylic polymer including silyl groups.
The amorphous powder (B) used in the present invention may be amorphous polymeric powder or amorphous silica. As for crystal materials such as calcium carbonate which are generally used as additives, they are apt to cause birefringence due to their optical anisotropy and lead to lower transparency due to light scattering so that they are unpreferable as additives in the present invention.
The polymeric powder used in the present invention is produced by emulsion polymerization, suspension polymerization or the like, and is commercially available. While (metha)acrylic acid, (metha)acrylate, vinyl acetate, ethylene and vinyl chloride are known as monomers for wide uses, the above-mentioned polymeric powder is made from a starting material of a polymer obtained by solely polymerizing one of these monomers or as the need arises by copolymerizing these monomers and one or more other monomers in consideration of particularly required properties such as adhesiveness or the like. Among monomers for wide uses as mentioned above, methylmethacrylate is particularly preferable since polymeric powder made therefrom is excellent in transparency, and weather resistance.
As the amorphous polymeric powder, poly(metha)acrylate powder, particularly, polymethylmethacrylate powder is preferably used. The advantages of polymethylmethacrylate powder used as the amorphous polymeric powder in the present invention are as follows: {circle around (1)} It exhibits low birefringence. {circle around (2)} It readily comes to hand because a plurality of makers place it on the market. {circle around (3)} It has a refractive index dose to those of polymers including silyl groups commercially available so that it readily affords transparency to the moisture curable composition of the present invention.
The refractive indexes of the amorphous materials and the polymers including silyl groups commercially available are shown in Table 1.
TABLE 1
Material
Refractive index
Polystyrene (PS)
1.59
Polycarbonate (PC)
1.59
Polyethylene (HDPE)
1.54
Polyvinyl chloride (PVC)
1.53
Polyethylene-vinyl acetate (EVA)
1.49
Polymethylmetacrylate (PMMA)
1.49
Polypropylene (PP)
1.48
SILYL MAX450 *1
1.47
SILYL SAT350 *2
1.45
Fused silica
1.45
*1 SILYL MAX450: a trade name of a mixture of a polymer with a main chain of polyoxypropylene having dimethoxysilyl groups at molecular terminals, and a polymer with a main chain of a copolymer of polymethacrylate having dimetoxysilyl groups in a molecule (manufactured by Kanegafuchi Chemical Industry Co., Ltd.).
*2 SILYL SAT350: a trade name of a polymer with a main chain of polyoxypropylene having dimethoxysilyl groups at molecular terminals (manufactured by Kanegafuchi Chemical Industry Co.).
Here, the blending parts by weight of the blended amorphous powder (B) with respect to 100 parts by weight of the mixture (A) are preferably in a range of 2 parts by weight to 300 parts by weight, more preferably in a range of 5 parts by weight to 150 parts by weight, and most preferably in a range of 10 parts by weight to 75 parts by weight, particularly from viewpoints of adhesiveness and flowability. If the blending parts by weight do not reach 2 parts by weight, sufficient adhesiveness cannot be provided. On the other hand, if it exceeds 300 parts by weight, the viscosity of the resultant composition becomes extremely high to make a cured composition fragile, thus leading to a lower bonding strength.
If the amorphous powder (B) has a grain diameter smaller than 0.01 &mgr;m, it is
Aoki Hiroshi
Egawa Yoshinobu
Hashimukai Hideharu
Horie Yasunobu
Oshima Yuichi
Arent Fox Kintner & Plotkin & Kahn, PLLC
Cemedine Co. Ltd.
Dawson Robert
Peng Kuo-Liang
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