Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
2002-06-28
2004-03-16
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036910, C428S035800, C428S461000, C428S462000, C138S137000, C138S140000, C138S145000
Reexamination Certificate
active
06706350
ABSTRACT:
BACKGROUND
The present invention relates to a pipe having its surface covered with a resin protective layer. In particular, the present invention relates to a pipe part material that can be used in any environment such as underground, indoors, or outdoors, has extremely wide application scope, and is appropriate for use as pipes for transportation of gas, petroleum materials, water, etc.
Steel pipes having a corrosion-proof protective layer in which the outer surface of the steel pipe has been covered with a comparatively thick thermoplastic resin film or cover, etc., in order to protect the steel pipe from corrosion have been widely used as pipelines for petroleum (crude oil), city gas supplying pipes, plant pipes, tap water or hot spring water supplying pipes, etc. Also, steel articles other than pipes, such as steel pipe pickets, steel plates, shaped steel, bar steel, etc., have utilized surface coverings of corrosion-proof resin.
As the thermoplastic resin used in the protective layer of these steel materials, polyolefins such as polyethylene, polypropylene, etc., have mainly been used, however, poly(vinyl chloride) resin, different polyamide resins, different fluorinated resins, different saturated polyester resins, etc., have also been used depending on the usage environment and required properties.
For example, a steel pipe having its surface covered with polyolefin resin as well as a pipe coupling has been presented in Japanese Patent Publication No. Sho 52-94519.
However, there existed good and bad points for each of these different thermoplastic resins, and a material having corrosion-proof characteristics that could protect the steel pipe under all types of environment could not be necessarily obtained. For example, the polyolefin variety that is used in most of the cases for a corrosion-proof covering of the steel material has excellent chemical resistance but low heat resistance, poor weatherability, and high combustibility. Also, its adhesion to steel is poor, and as a result a complicated manufacturing process is required in which a modified polyolefin adhesive layer is applied over a coating of epoxy primer.
Also, the poly(vinyl chloride) resin has excellent flame retardance but low stability, and hydrochloric acid is gradually released. Moreover, polyamide and saturated polyester resins have high moisture absorption and thus possess low electric resistance in underground environments, particularly underground in damp soil. There therefore exists a possibility of the main material getting electrically corroded. Fluorinated resin has excellent corrosion resistance, flame retardance, stability, and electrical resistance, but it is extremely expensive and moreover has poor adhesion to steel, which detracts from its corrosion-proofing properties. Furthermore, since it has a high melting point, it requires a high temperature of more than 400° C. for its adhesion.
The formation of a protective layer from polyphenylene ether resin has also been proposed. For example, Japanese Patent Publication No. Hei 8-238717 describes a steel pipe possessing a covering formed from a polyphenylene ether resin composition containing (1) 100 parts by weight of a resin component formed from polyphenylene ether resin (A) contained in a quantity of 10 to 100% by weight and styrene polymer (B) contained in a quantity of 90 to 0% by weight, (2) 0 to 50 parts by weight of a rubber component formed from styrene rubber polymer, and (3) 0 to 40 parts by weight of a flame retardant.
However, the polyphenylene ether resin described in the Japanese Patent Publication No. Hei 8-238717 has low chemical resistance compared to that of polyolefin resin, so excellent corrosion-proofing could not be obtained even by forming a protective layer. Also, use of the polyphenylene ether resin or its composition was associated with problems such as poor adhesion, a complicated manufacturing process, etc.
BRIEF SUMMARY
The present invention aims at offering a resin-covered pipe that has high heat resistance and excellent flame retardance, corrosion-resistance, chemical resistance, insulation properties, and sufficiently high adhesion to steel, as well as low cost.
One embodiment is a corrosion-resistant pipe, comprising:
a pipe; and
a protective layer covering a surface of the pipe, the protective layer comprising
(A) 1 to 98 parts by weight of a polyphenylene ether resin,
(B) 1 to 98 parts by weight of a polystyrene resin,
(C) 1 to 98 parts by weight of a polyolefin resin,
wherein the total of (A), (B), and (C) is 100 parts by weight; and
(D) 0.1 to 100 parts by weight of a compatibility reagent per 100 parts by weight total of (A), (B), and (C).
Another embodiment is a corrosion-resistant pipe, comprising:
a pipe; and
a protective layer covering a surface of the pipe, the protective layer comprising
(A) 1 to 98 parts by weight of a polyphenylene ether,
(B) 1 to 98 parts by weight of a polystyrene resin,
(C) 1 to 98 parts by weight of a polyolefin resin,
wherein the total of (A), (B), and (C) is 100 parts by weight;
(D) 0.1 to 100 parts by weight of a compatibility reagent (D) per 100 parts by weight total of (A), (B), and (C), and
(E) 0 to 100 parts by weight of an impact modifier per 100 parts by weight total of (A), (B), and (C).
The quantity of polystyrene resin (B) present in the resin composition mentioned above is preferably more than 10% by weight with respect to the total of polyphenylene ether resin (A) and polystyrene resin (B).
Also, the compatibility reagent (D) is preferably a hydrogenated styrene.diene block copolymer, which preferably has a styrene content more than 60% by weight.
In the present invention, the protective layer is preferably a film formed from the resin composition or an injection molded product of the resin composition.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A detailed explanation of the corrosion-resistant pipe of the present invention is given below.
The surface of the corrosion-resistant pipe of the present invention is covered with the resin composition containing polyphenylene ether resin (A), polystyrene resin (B), polyolefin resin (C), and compatibility reagent (D).
Polyphenylene ether resin (A)
There is no particular restriction on the material that can be used as polyphenylene ether resin (PPE resin) and well-known materials can be used. Suitable PPE resins include polymers having structural units shown by the general formula (I) below
wherein each of R
1
, R
2
, R
3
, and R
4
is hydrogen atom, halogen atom, hydrocarbon radical, substituted hydrocarbon radical, alkoxy radical, cyano radical, phenoxy radical, or nitro radical; and n is an integer showing the degree of polymerization.
The polyphenylene ether resin used in the present invention can be in form of a homopolymer formed from one type of structural units shown by the general formula given above or can be in the form of a copolymer having two or more than two types combined.
Concrete examples of R
1
, R
2
, R
3
, and R
4
, include radicals such as chlorine, bromine, iodine, methyl, ethyl, propyl, allyl, phenyl, benzyl, methyl benzyl, chloro benzyl, bromomethyl, cyanoethyl, cyano, methoxy, ethoxy, phenoxy, nitro, etc.
Concrete examples of the polyphenylene ether resin include poly (2,6-dimethyl-1,4-phenylene ether), poly (2,6-diethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), poly (2-methyl-6-propyl-1,4-phenylene ether), poly (2,6-dipropyl-1,4-phenylene ether), poly (2-ethyl-6-propyl-1,4-phenylene ether), poly (2,6-dimethoxy-1,4-phenylene ether), poly (2,6-dichloro methyl-1,4-phenylene ether), poly (2,6-dibromo methyl-1,4-phenylene ether), poly (2,6-diphenyl-1,4-phenylene ether), poly (2,6-di toluyl-1,4-phenylene ether), poly (2,6-dichloro-1,4-phenylene ether), poly (2,6-dibenzyl-1,4-phenylene ether), poly (2,5-dimethyl-1,4-phenylene ether), etc.
An especially preferred PPE resin is the polymer having alkyl radicals, particularly, alkyl radicals having 1 to 4 carbon atoms, as the R
1
and R
2
occurring in the formula (I) given above, and n is preferably more than 50. Preferr
Amaya Yoshinori
Sato Sho
Bruenjes Christopher
General Electric Company
Pyon Harold
LandOfFree
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