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
2001-12-12
2004-05-04
Mulcahy, Peter D. (Department: 1713)
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...
C524S431000, C524S432000, C524S433000, C428S036900
Reexamination Certificate
active
06730727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a colored resin composition for water distribution pipes and a colored resin water distribution pipe comprising said composition, and more particularly to a colored resin composition for water distribution pipes which shows excellent fastness of the coloring component to water containing chlorine and a colored resin water distribution pipe comprising said composition.
2. Description of the Related Arts
Heretofore, water distribution pipes in Japan are pipes made of steel, ductile cast iron, or polyvinyl chloride. However, it was confirmed that water distribution pipes made of these materials showed formation of crazings and cracks by the earthquake which occurred in the HANSHIN-AWAJI area and were vulnerable to seismic deformation.
On the other hand, polyethylene pipes used as gas pipes or water distribution pipes showed little damage by formation of crazings and cracks in recent occurrences of earthquake, such as the earthquake in the sea off KUSHIRO, HOKKAIDO in January, 1993 (M: 7.8), the earthquake in the sea off the southwest coast of HOKKAIDO in July, 1993 (M: 7.8), and the earthquake in the HANSHIN-AWAJI area in January, 1995 (M: 7.2), and it was shown that polyethylene pipes have excellent resistance to seismic deformation. For water feed pipes made of polyethylene, LD polyethylene and LLD polyethylene are used as the material resin. Single layer pipes made of the above resin colored with carbon black and double layer pipes having an outer pipe made of the above resin colored with carbon black and an inner pipe made of the above resin without coloring are actually used. However, single layer pipes colored with a blue pigment are mainly used as water distribution pipes in the United States and Europe, and research and development on single layer pipes are being conducted in Japan with the prospect of using single layer pipes in future. The water distribution pipe refers to a main pipe used for distributing water from a water tower or a water pool to individual houses, and the water feed pipe refers to a pipe used for feeding water from the main pipe to terminals in individual houses.
As the pigment used for providing polyethylene with a blue color, a copper phthalocyanine blue pigment is generally used because of excellent weatherability. When pipes for water are provided with a color, it is essentially required that a used pigment show little discoloration in a test of resistance to water containing chlorine and that the inner face of the pipe do not show deformation, such as deformation caused by blisters. The copper phthalocyanine blue pigment show poor resistance to oxidizing agents and is markedly discolored in a test of resistance to water containing chlorine, resulting in almost white color.
SUMMARY OF THE INVENTION
Accordingly, the objects of the present invention are to provide a colored resin composition for water distribution pipes which is made of a polyolefin and comprises a blue pigment of a composite oxide showing excellent resistance to water containing chlorine as the bactericide so that the coloring component show excellent fastness of color to water containing chlorine and formation of blisters on the inner face of the pipe can be prevented; and to provide a pipe comprising this composition.
As the result of extensive studies by the present inventors to overcome the above problems, it was found that a colored polyolefin resin composition showing little discoloration or formation of blisters by water containing chlorine as the bactericide can be obtained by using, as the blue pigment for coloring a polyolefin resin, a blue fine powder pigment comprising a composite oxide which comprises oxides of two or more metals and has a crystal structure of a spinel type and a particular specific surface area or a blue pigment of a composite oxide treated with a compound. The present invention has been completed on the basis of this knowledge.
Accordingly, the present invention provides:
(1) A colored resin composition for water distribution pipes comprising a resin which comprises a polyolefin resin as a main component and a blue fine powder pigment of a composite oxide which comprises two or more metal oxides and has a spinel type crystal structure and a BET specific surface area of about 30 m
2
/g or more;
(2) A colored resin composition for water distribution pipes comprising a resin which comprises a polyolefin resin as a main component and a blue pigment of a composite oxide which comprises two or more main metal oxides, has a spinel type crystal structure, and contains one or more elements other than metals of the main metal oxides in the crystal structure;
(3) A colored resin composition for water distribution pipes comprising a resin which comprises a polyolefin resin as a main component and a blue pigment of a composite oxide which comprises two or more main metal oxides, has a spinel type crystal structure, and has been treated with one or more compounds of elements other than metals of the main metal oxides mechanochemically by grinding;
(4) A composition described in any of (1), (2), and (3), wherein the blue pigment of a composite oxide is a composite oxide containing cobalt and aluminum as metals of the metal oxides;
(5) A composition described in any of (1), (2), (3), and (4), wherein the blue pigment of a composite oxide is a blue fine powder pigment of one composite oxide or a mixture of two or more composite oxides which are selected from the group consisting of composite oxides containing cobalt and aluminum as metal components, composite oxides containing cobalt, aluminum, and titanium as metal components, composite oxides containing cobalt, aluminum, and chromium as metal components, and composite oxides containing cobalt, aluminum, chromium, and titanium as metal components;
(6) A composition described in any of (1), (2), (3), (4), and (5), wherein the blue pigment of a composite oxide is obtained by dissolving salts of metals constituting the composite oxide in water, forming coprecipitates of compounds comprising oxides, hydroxides, and/or carbonates of the metals from the resultant solution using a precipitating agent, and baking the formed coprecipitates;
(7) A composition described in any of (1), (2), (3), (4), and (5), wherein the blue pigment of a composite oxide is obtained by dissolving salts of metals constituting the composite oxide and urea in water, forming coprecipitates of compounds comprising oxides, hydroxides, and/or carbonates of the metals by heating the resultant solution, and baking the formed coprecipitates;
(8) A composition described in any of (1), (2), (3), (4), (5), (6), and (7), wherein the blue pigment of a composite oxide is covered with a synthetic resin and/or an inorganic compound;
(9) A composition described in any of (1), (2), (3), (4), (5), (6), (7), and (8), wherein the polyolefin resin is a polyethylene resin; and
(10) A colored resin water distribution pipe comprising a colored resin composition described in any of (1), (2), (3), (4), (5), (6), (7), (8), and (9).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The resin used in the present invention which comprises a polyolefin resin as a main component is a conventional polyolefin resin used for extrusion molding or injection molding. Specific examples include homopolymers of ethylene and block copolymers of ethylene and propylene containing 1 to 50% by weight of ethylene and 99 to 50% by weight of propylene, which have a density of 0.91 to 0.980 g/cm
3
, preferably 0.940 to 0.960 g/cm
3
, and an MFR of 0.01 to 10.0 g/10 minutes, preferably 0.05 to 1.0 g/10 minutes. Block copolymers obtained by replacing a portion of ethylene or propylene in the above block copolymer with an olefin having 4 to 6 carbon atoms can also be used.
The present invention is described more specifically with reference to preferable embodiments.
The blue pigment used in the colored resin composition for water distribution pipes of the present invention is a blue pigment of a complex metal oxide, i.e
Abe Yoshio
Kawakami Toru
Momoi Yasutaka
Nakamura Michiei
Noda Mitsuo
Dainichiseika Color & Chemicals Mfg. Co. Ltd.
Frishauf Holtz Goodman & Chick P.C.
Mulcahy Peter D.
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