Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
2002-02-25
2004-08-24
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S421000, C428S036910, C428S036900, C525S330600
Reexamination Certificate
active
06780483
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a laminate comprising a fluorine-containing polymer. In particular, the present invention relates to a laminate comprising a layer of a tetrafluoroethylene copolymer having a carbonate group and a layer of a polyolefin resin.
BACKGROUND ART
Fluorine-containing polymers are used in various applications since they have excellent heat resistance, chemical resistance, surface properties (e.g. low abrasion properties, etc.) and electrical insulating properties. However, the fluorine-containing polymers have generally insufficient mechanical strength or dimensional stability, or they are expensive.
Thus, various attempts such as the adhesion or lamination of the fluorine-containing polymer to other organic material or an inorganic material have been made to make the best use of advantages of the fluorine-containing polymers while minimizing their disadvantages.
However, the fluorine-containing polymers inherently have a low adhesion force so that it is difficult to adhere them directly to other material. Even if fusion bonding is tried, the adhesion strength is insufficient, or when a certain level of adhesion strength is attained, the adhesion force tends to vary with a kind of a substrate. Thus, the reliability of the adhesion is often insufficient.
To adhere the fluorine-containing polymers to other material, the following methods are mainly discussed:
1. Physically roughening the surface of a substrate with sand bluster treatment, etc.;
2. Surface treatment of a fluorine-containing polymer by sodium etching, plasma treatment, photochemical treatment, etc.;
3. Adhesion with an adhesive.
The methods 1 and 2 require the treatment process and the treatment steps are complicated, and thus their productivity is low. In addition, in the methods 1 and 2, the kinds and shapes of the substrates are limited. Anyhow, the adhesion force achieved by the methods 1 and 2 is low, and the appearance of the resulting laminate tends to have some problems (e.g. coloring, flaws, etc.).
Various adhesives to be used in the method 3 are examined. Conventional hydrocarbon base adhesives have insufficient adhesion properties, and their own heat resistance is insufficient. Therefore, such adhesives cannot generally withstand adhering conditions for the fluorine-containing polymers which require molding or processing at high temperature, and they suffer from delamination or coloration due to decomposition. The laminates using such adhesives cannot maintain the adhesion force due to the change of temperature and environment and lack reliability since their adhesive layers have insufficient heat resistance, chemical resistance or water resistance.
Alternatively, adhesion with an adhesive or an adhesive composition comprising a fluorine-containing polymer having a functional group is studied.
Prior arts disclose, as an adhesive, the use of a fluorine-containing polymer to which a hydrocarbon monomer having a carboxyl group, a carboxylic anhydride group, an epoxy group or a hydrolyzable silyl group (e.g., maleic anhydrice, vinyltrimethoxysilane, etc.) is grafted (e.g., JP-A-7-18035, JP-A-7-25952, JP-A-7-25954, JP-A-7-173230, JP-A-7-173446, JP-A-7-173447, etc.), or the use of a cured material of an adhesive composition containing a fluorine-containing copolymer which comprises a hydrocarbon monomer having a functional group such as hydroxyalkyl vinyl ether copolymerized with tetrafluoroethylene, chlorotrifluoroethylene, etc., and a isocyanate curing agent as an adhesive for adhering polyvinyl chloride to ETFE (ethylene-tetrafluoroethylene copolymer) which has been treated with corona discharge (e.g., JP-A-7-228848).
The adhesive or adhesive composition comprising the fluorine-containing polymer to which the functional hydrocarbon monomer is grafted or copolymerized has insufficient heat resistance. Thus, it decomposes and foams so that the adhesion strength decreases, or the layers are delaminated or colored, when it is processed together with the fluororesin or used at a high temperature. The adhesive composition disclosed in JP-A-7-228848 requires the corona discharge treatment of the fluororesin.
Furthermore, it is reported to use a fluorine-containing 25 polymer having a functional group, which is prepared by copolymerizing a perfluorovinyl ether having a carboxylic acid group or its derivative with a fluorine-containing monomer, as an adhesive or an adhesive composition. US Pat. No. 4,916,020 discloses a laminate using a fluorine-containing polymer having a functional group which is introduced in the polymer by copolymerizing a perfluorovinyl ether having a carboxylic acid group or its derivative with tetrafluoroethylene, etc.
In this laminate, the above-described fluorine-containing polymer having a carboxylic acid group, etc. is laminated on other substrate such as a metal substrate through an adhesive resin such as an epoxy resin, a urethane resin, etc. Thus, the epoxy resin or the urethane resin has problems in its heat resistance, chemical resistance or solvent resistance when the laminate is used.
WO98/58973 (published on Dec. 30, 1998) discloses a laminate comprising a layer of a tetrafluoroethylene copolymer having a terminal carbonate group, a layer of other material such as a thermoplastic resin, and an intermediate layer between them. One example described in this WO publication is a laminate comprising an intermediate layer of an epoxy group-containing polyethylene when polyethylene is used as the other material.
When the layer of the tetrafluoroethylene copolymer having a terminal carbonate group and the polyethylene layer are adhered with the epoxy group-containing polyethylene, the initial adhesion force is high, but the adhesion force tends to decrease with time. In addition, the epoxy group-containing polyethylene itself has low resistance to fuel and is dissolved in the fuel. Thus, this laminate cannot be used to fabricate a tube or a tank for storing the fuel.
DISCLOSURE OF THE INVENTION
one object of the present invention is to provide a laminate which comprises a layer of a tetrafluoroethylene copolymer having a carbonate group and a layer of a polyolefine resin strongly adhered to each other, the adhesion strength of which does not decrease with time, and which has high resistance to fuel.
According to the present invention, the above object is achieved by a laminate comprising
(1) a layer of a tetrafluoroethylene copolymer comprising 30 to 81% by mole of tetrafluoroethylene and 70 to 19% by mole of at least one other monomer and having a carbonate group in a polymer chain or at a polymer chain terminal, which has a melt flow rate of 0.1 to 100 g/10 minutes (230° C., 5 kg-load) and a melting point of 90 to 230° C.,
(2) a layer of an ethylene-vinyl acetate copolymer formed on one surface of the layer (1), which satisfies the following relationship:
X×Y
/100≧7.0
wherein X is a vinyl acetate content (% by mole) and Y is a saponification degree of a methyl ester (%), and
(3) a layer of a polyolefin resin formed on the layer (2).
The carbonate group contained in the tetrafluoroethylene copolymer to be used in the present invention is a group having a bond of the formula: —OC(═O)O—, and a specific example of the carbonate group is a group of the formula: —OC(═O)O—R wherein R is a hydrogen atom, an organic group (e.g. a C
1
-C
20
alkyl group, a C
2
-C
20
alkyl group having an ether linkage, etc.), or an element of the I, II or VII Group. Preferable examples of the carbonate group include —OC(═O)O—CH
3
, —OC(═O)O—C
3
H
7
, —OC(═O)O—C
8
H,
17
, —OC(═O)O—CH
2
CH
2
OCH
2
CH
3
, and the like.
The tetrafluoroethylene copolymer having a carbonate group at a polymer chain terminal means a tetrafluoroethylene polymer having a functional group comprising a carbonate group on at least one terminal of the polymer chain. The tetrafluoroethylene copolymer having a carbonate group in a polymer chain means a copolymer prepared by copolymerizing an ethylenically unsaturated monomer having a carbonate group and te
Higuchi Tatsuya
Ishiwari Kazuo
Kitahara Takahiro
Ozaki Hidenori
Birch & Stewart Kolasch & Birch, LLP
Daikin Industries Ltd.
Pyon Harold
Simone Catherine A.
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