JPH0216699B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite barrier membrane;
More specifically, the present invention relates to a composite barrier film having excellent weather resistance, which is formed by providing a cured coating film of a specific fluorine-containing copolymer on a polyethylene terephthalate film.

Polyethylene terephthalate film has excellent gas barrier properties and has been put to practical use in a wide range of applications such as food packaging materials. However, this film has poor weather resistance and cannot be used as a membrane material in outdoor applications such as balloons and air membrane structures.

The inventors of the present invention have conducted intensive research based on the recognition of the above problems, and have found that by providing a cured coating film of a specific fluorine-containing copolymer on the film, weather resistance is significantly improved. It was discovered that a composite barrier membrane can be obtained which is also applicable to outdoor applications.

Thus, the present invention has been completed based on the above findings, and consists of a polyethylene terephthalate film containing 20 moles of units based on a monomer that mainly consists of units based on tetrafluoroethylene and alkyl vinyl ether and further provides reaction sites. The object of the present invention is to provide a novel composite barrier film characterized by being provided with a cured coating film of a fluorine copolymer containing a fluorine copolymer in a proportion of not more than 5%.

In the present invention, various polyethylene terephthalate films can be used, such as unstretched films, uniaxially stretched films, and biaxially stretched films, but biaxially stretched films are preferably employed from the viewpoint of mechanical strength. The thickness of the film is usually 5 to 100 μm, preferably 10 to 100 μm.
Appropriate selection is made from a range of 60 μm depending on the application.

In the present invention, a fluorine-containing copolymer containing units based on tetrafluoroethylene and alkyl vinyl ether as main components and units based on monomers providing reactive sites in a proportion of 20 mol% or less is provided on the above film. It is important to provide a cured coating. Such a coating film provides a composite film that is not only weather resistant but also has excellent flexibility and durability.

Here, the content ratio of units based on tetrafluoroethylene and alkyl vinyl ether in the fluorine-containing copolymer is preferably in the range of about 70:30 to 30:70 from the viewpoint of weather resistance, solubility, flexibility, etc. Examples of preferable alkyl vinyl ether components that can be employed include those containing a linear, branched or cyclic alkyl group having about 2 to 8 carbon atoms, from the viewpoint of copolymerization properties and coating film properties. The component may contain units based on two or more alkyl vinyl ethers. As a comonomer that provides a reactive site in such a copolymer, functional group-containing vinyl ethers such as hydroxyalkyl vinyl ether or glycidyl vinyl ether can be preferably employed from the viewpoint of copolymerization properties. The content of units based on comonomers that provide reactive sites in the copolymer is 20 mol% or less,
Preferably it is about 1 to 15 mol%. If the ratio is too small, curing will be insufficient, and if it is too large, the flexibility of the coating film will be impaired, both of which are disadvantageous. In addition to these three essential components, other comonomer-based units may be added, e.g.
A modified copolymer containing 15 mol% or less can also be used.

The above copolymers are produced by causing a copolymerization reaction by causing a polymerization initiator or a polymerization initiation source such as ionizing radiation to act on a monomer mixture of a predetermined ratio in the presence or absence of a polymerization medium. Therefore, it can be manufactured.

In the present invention, the fluorine-containing copolymer cured coating film can be formed by various methods, but from the viewpoint of operability, the fluorine-containing copolymer is dissolved in a solution of the fluorine-containing copolymer in an organic solvent. A curing agent such as a polyfunctional compound that is reactive with the reactive site of the polymer is added to the copolymer 100.
About 0.1 to 100 parts by weight, preferably
Preferably, a method can be adopted in which a coating composition is prepared by containing it in a proportion of about 0.5 to 50 parts by weight, and the composition is applied onto the film by various methods to volatilize the solvent and cure the coating film. It is. A curing aid or curing catalyst may be appropriately added to the composition.

In the case of such a method, polyvalent isocyanate or titanium alkoxide can be preferably employed as a curing agent for a fluorine-containing polymer whose reactive site is a hydroxyl group when the composition is to be cured at room temperature. In addition, when the composition is of a heat curing type, a melamine curing agent, a urea resin curing agent, such as those used in ordinary heat curing acrylic paints,
Polybasic acid curing agents and the like are effective as curing agents. Here, examples of the melamine curing agent include butylated melamine, methylated melamine, epoxy-modified melamine, etc., and various degrees of modification from 0 to 6 can be used depending on the application, and the degree of self-condensation can also be selected as appropriate. be able to. Examples of urea resin include methylated urea,
Examples include butylated urea. Useful polybasic acid curing agents include long-chain aliphatic polycarboxylic acids, aromatic polycarboxylic acids or their anhydrides, and blocked polyisocyanates. When using a melamine or urea curing agent, curing can be accelerated by adding an acidic catalyst. As another example, when the reactive site of the fluorine-containing polymer is an epoxy group, amines, carboxylic acids, phenols, alcohols, etc. are effective as curing agents. Aromatic diols are useful as curing aids. The thickness of the cured coating film of the fluorine-containing copolymer thus obtained is usually 5 to 60 μm, preferably 10 to 60 μm.
Appropriately selected from a range of 30 μm.

In the present invention, it is also possible to add various components such as ultraviolet absorbers, colorants, and water repellency imparting components to the cured coating film to improve various properties such as durability, aesthetics, and water repellency. be. Furthermore, it is of course possible to increase the mechanical strength by laminating a fibrous material on the surface opposite to the coating surface.

The composite barrier film of the present invention not only has excellent weather resistance, but also has the advantage of being lightweight because the film and the cured coating film are firmly bonded without using an adhesive. It is extremely useful as an outdoor coating material for objects, etc.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 The following coating composition was prepared using fluorine-containing copolymers containing units based on tetrafluoroethylene, ethyl vinyl ether, and hydroxybutyl vinyl ether in proportions of 50 mol%, 40 mol%, and 10 mol%, respectively. Prepared.

Fluorine-containing copolymer 100 parts by weight Isocyanate curing agent (Sumitomo Bayer Urethane: Dismodyur N) 10 parts by weight Dibutyl tin dilaurylate 0.003 〃 Mixed solvent 200 〃 However, the mixed solvent is methyl isobutyl ketone,
It is a mixture of xylene, ethyl acetate and cellosolve acetate in a weight ratio of 1:1:1:0.5.

The coating composition obtained above was applied to a commercially available polyethylene terephthalate biaxially stretched polyester film (thickness 38 μm; manufactured by Diafoil: Diafoil #
38) A composite barrier film having a cured coating was obtained by spray-coating the coating to a dry film thickness of 20 μm and leaving it at room temperature for 7 days to cure the coating.

The composite barrier film thus obtained has adhesion that does not cause damage even in the Dupont impact test with a steel ball diameter of 1/2", a load of 500 g, and a drop height of 50 cm.
It exhibits excellent gas barrier properties, and even after 400 hours of accelerated weathering tests using a dual-cycle weather meter, it still maintains 100% and 98% of its initial value.
It maintained tensile strength and elongation equivalent to .

On the other hand, in the case of a single polyester film without the above-mentioned cured coating, the tensile strength and elongation of the film remained at their initial values after 200 hours of the same accelerated weathering test using a dual-cycle weather meter. decreased to 67% and 44%.

Example 2 A fluorine-containing copolymer containing units based on tetrafluoroethylene, cyclohexyl vinyl ether, isobutyl vinyl ether, and hydroxybutyl vinyl ether in proportions of 50 mol%, 25 mol%, 20 mol%, and 5 mol%, respectively, was used. , the following coating composition was prepared.

Fluorine-containing copolymer 100 parts by weight Titanium oxide (Ishihara Sangyo: CR-90) 50 Mixed solvent 150 Melamine resin (Mitsui Toatsu: Cymel 325)
8 Same curing catalyst (same as above: Catalyst 6000)
0.05 〃 The mixed solvent is xylene, butanol, ethyl cellosolve, and high boiling point aromatic solvent (manufactured by Tonen:
Sorbetso #150) was mixed in a weight ratio of 1:1:1:3.

The above coating composition was applied onto the same film as in Example 1 using a roll coater so that the dry film thickness was 20 μm, and baked and cured at 120° C. for 40 minutes.

The tensile strength and elongation retention rates of the thus obtained composite barrier membrane after 400 hours of accelerated weathering test using a due-cycle weather meter were as follows:
They were 100% and 70%. Moreover, the composite membrane is 0T
Even after repeating the bending process 10 times, no damage such as cracks was observed.

Claims (1)

[Claims] 1 On the polyethylene terephthalate film,
A cured coating film of a fluorine-containing copolymer containing units based on tetrafluoroethylene and alkyl vinyl ether as main components and further containing units based on a monomer that provides a reactive site in a proportion of 20 mol% or less. Characteristic composite barrier membrane.