Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
2001-12-04
2004-02-03
Le, H. Thi (Department: 1773)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C427S149000, C427S149000, C427S212000, C427S220000
Reexamination Certificate
active
06686044
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to modified calcium carbonate particles, to a method for producing these particles, and to an adhesive containing these particles.
(2) Description of the Related Art
When calcium carbonate is used as a filler for an adhesive, the calcium carbonate is required to exhibit certain properties, such as (a) being excellent in dispersibility in the resin and other components of the adhesive, (b) improving the adhesion between the adhesive and the adherend(s), and (c) stabilizing the viscosity of the adhesive during storage in the product container.
The reasons why the calcium carbonate particles need to have properties (a) to (c) are as follows.
The resin and other components must be mixed with calcium carbonate at a high shear force and for a long time to uniformly disperse the calcium carbonate particles in the resultant mixture. When the calcium carbonate has excellent dispersibility, less energy and time are needed, which leads to lower production cost.
When the adhesion is poor between an adhesive and its adherend, sliding (slip) occurs between the adherend and the adhesive before curing of the adhesive is complete. Consequently, the targeted bonding precision and sealing function cannot be obtained with the sliding remaining between the adherend and the adhesive.
When the viscosity or the thixotropic properties of an adhesive change while the adhesive is stored in its container, the adhesive becomes difficult to handle and bonding and sealing properties will be impaired, among other problems.
However, the conventional calcium carbonate materials are not satisfactory in the above required properties (a) to (c)
For instance, Japanese Unexamined Patent Publication No. 349846/1999 discloses a calcium carbonate material that has been surface treated with at least one compound selected from the group consisting of saturated fatty acids, unsaturated fatty acids, alicyclic carboxylic acids and resin acids. The Publication states that the treated calcium carbonate is suitable as a filler for resin, and that when the treated calcium carbonate is used as an additive in a curable resin composition, thermal resistance of the composition will be excellent during drying and superior thixotropic properties and slumping resistance and good storage stability can be imparted to the composition.
However, the thixotropic properties of the calcium carbonate are not satisfactory, and, as a result, the performance requirement (c) above is not fully met. Furthermore, the calcium carbonate is not sufficiently improved also in terms of the requirements (a) and (b) above.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide calcium carbonate particles that fulfil the performance requirements (a) to (c) discussed above.
It is another object of the present invention to provide surface-coated calcium carbonate particles capable of easily dispersing in a mixture of resin and other components that constitute an adhesive composition, and imparting excellent viscosity stability and adhesion to the resulting adhesive.
It is a further object of the present invention to provide a method for producing the above-mentioned surface-coated calcium carbonate particles.
It is a further object of the present invention to provide an adhesive containing the above-mentioned surface-coated calcium carbonate particles.
The inventors conducted research aimed at achieving the stated objects. As a result, the inventors found that calcium carbonate particles excellent in properties (a) to (c) above can be obtainable by coating a starting calcium carbonate particles with (1) a mixture of (1A) at least one compound selected from the group consisting of saturated fatty acids and salts thereof and (1B) at least one compound selected from the group consisting of unsaturated fatty acids and salts thereof to form a first coating layer, and then coating the coated calcium carbonate particles with (2) a particular organic compound to form a second coating layer. The present invention was accomplished on the basis of above finding.
The invention provides surface-coated calcium carbonate particles, in which the surface of calcium carbonate particles is coated with a fatty acid mixture and further with an organic compound,
the fatty acid mixture (1) comprising (1A) at least one compound selected from the group consisting of saturated fatty acids and salts thereof and (1B) at least one compound selected from the group consisting of unsaturated fatty acids and salts thereof, the (1A):(1B) weight ratio being in the range of 30:70 to 70:30,
the coating amount of the fatty acid mixture being about 1 to about 3 mg per square meter of BET specific surface area of the surface-coated calcium carbonate particles,
the organic compound being at least one member selected from the group consisting of phthalic esters, phosphoric esters, adipic esters, sebacic esters, azelaic esters, trimellitic esters and metal alkoxides, and
the coating amount of the organic compound being about 0.1 to about 1 mg per square meter of BET specific surface area of the surface-coated calcium carbonate particles.
The present invention also provides the above-mentioned surface-coated calcium carbonate particles, wherein the BET specific surface area of the surface-coated calcium carbonate particles is about 10 to about 40 m
2
/g, the peak for primary pore diameter on a pore diameter distribution curve measured by mercury porosimetry is about 0.03 to about 0.08 &mgr;m, and the primary pore volume is about 0.1 to about 0.5 cm
3
/g.
The present invention also provides a method for producing surface-coated calcium carbonate particles comprising steps of:
coating calcium carbonate particles with (1) a fatty acid mixture comprising (1A) at least one compound selected from the group consisting of saturated fatty acids and salts thereof and (1B) at least one compound selected from the group consisting of unsaturated fatty acids and salts thereof to form a first coating layer, the (1A):(1B) weight ratio being in the range of 30:70 to 70:30, and the amount of coating fatty acid mixture being about 1 to about 3 mg per square meter of BET specific surface area of the surface-coated calcium carbonate particles, and
coating the coated calcium carbonate particles with (2) at least one organic compound selected from the group consisting of phthalic esters, phosphoric esters, adipic esters, sebacic esters, azelaic esters, trimellitic esters and metal alkoxides to form a second coating layer, the amount of coating of the organic compound being in the range of about 0.1 to about 1 mg per square meter of BET specific surface area of surface-coated the calcium carbonate particles.
The present invention also provides an adhesive containing the above-mentioned surface-coated calcium carbonate particles having two coating layers.
The present invention also provides a method for imparting excellent viscosity stability and high adhesion to an adhesive by adding the above-mentioned modified calcium carbonate particles.
Other features of the present invention will become clear from the following description.
DETAILED DESCRIPTION OF THE INVENTION
Surface-coated Calcium Carbonate Particles
In the surface-coated calcium carbonate particles of the present invention, the particle surface has (i) a first coating layer of (1) a fatty acid mixture composed of (1A) at least one compound selected from the group consisting of saturated fatty acids and salts thereof and (1B) at least one compound selected from the group consisting of unsaturated fatty acids and salts thereof and (ii) a second coating layer of (2) at least one organic compound selected from the group consisting of phthalic esters, phosphoric esters, adipic esters, sebacic esters, azelaic esters, trimellitic esters and metal alkoxides.
The starting calcium carbonate particles can be any product produced by a known method. Therefore, the present invention allows the use of both natural calcium carbonate particles (heavy calcium bicarbonate particl
Fukuda Takao
Hosoi Kazuyuki
Nakai Go
Larson & Taylor PLC
Le H. Thi
Shiraishi Kogyo Kaisha, Ltd.
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