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...
Patent
1994-12-13
1996-06-25
Reddick, Judy M.
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...
156327, 427256, 427223, 427316, 427322, 427536, 427537, 4273935, 524379, 524557, 524503, 525 61, C08K 505
Patent
active
055300464
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for producing an oxidation-treated polymer solution comprising oxidizing a saponified ethylene-vinyl acetate copolymer (hereinafter sometime referred to briefly as EVOH) in a solution form and a method for producing a laminate having an oxygen-barrier property which comprises coating the surface of a substrate, such as a plastic substrate, with the oxidation-treated polymer solution.
BACKGROUND OF THE INVENTION
The film obtainable from EVOH is transparent and excellent in oxygen-barrier property and, therefore, laminates of EVOH film with other plastic film, paper, metal foil, etc. are useful packing materials for foodstuffs, pharmaceutical products, industrial chemicals and so on.
Any desired technique available can be employed for forming an EVOH film on a substrate but the solution coating method comprising coating the surface of a substrate with a solvent solution of EVOH is attracting attention because a comparatively thick film can be formed, the film can be easily formed even on a substrate having a complicated profile, such as a hollow vessel, and the coating can be performed with a comparatively simple apparatus.
However, a solution obtainable by dissolving the ordinary EVOH in a solvent mixture of water and alcohol has a poor storage stability, i.e. a short pot life, and when stored at room temperature, becomes opacified in a few days and ultimately solidifies. Therefore, it is poor in handlability, requiring a field operation, such as redissolving EVOH by heating the solution at 60.degree.-80.degree. C. for a few hours, for instance, immediately before use. Furthermore, this EVOH solution is so high in viscosity that it is inferior in high-speed coatability.
For improving the stability of an EVOH solution, a method comprising adding boric acid to EVOH has been proposed (Kokai Tokkyo Koho H-2-47144) but even with such contrivances the storage stability cannot be said to be sufficient. Moreover, because of the high viscosity, the high-speed coatability is not improved at all.
Thus, the conventional ordinary EVOH solution or the solution prepared by adding boric acid thereto is unsuitable as a coating.
Kokai Tokkyo Koho H-4-500834 describes the use, in a polymer composition for the production of a biodegradable plastic product made up of a modified starch and a synthetic polymer comprising EVOH or polyvinyl alcohol, of a polymer oxidized by reaction with hydrogen peroxide and persulfuric acid as said polymer.
However, when EVOH is dissolved in a solvent and oxidation-modified by the reaction with hydrogen peroxide and persulfuric acid, the problem remains that the resulting oxidation-treated polymer solution becomes colorized, its standing stability is adversely affected, and the gas-barrier property of the coating film is sacrified.
OBJECTS OF THE INVENTION
Under the circumstances the present invention has for its object to provide a method for producing an EVOH solution having good standing stability and high-speed coatabality and capable of forming a film with good gas-barrier property and transparency and a method for producing a laminate comprising coating a substrate with said EVOH solution.
SUMMARY OF THE INVENTION
The method for producing an oxidation-treated polymer solution in accordance with the present invention is characterized by using a saponified ethylene-vinyl acetate copolymer (EVOH) satisfying all the following relations
where Et (mol %) represents the ethylene content of saponified ethylene-vinyl acetate copolymer (EVOH), SV (mol %) represents the degree of saponification of EVOH, and Tm (.degree.C.) represents the melting point of EVOH as found from the peak temperature measured with a differential scanning calorimeter, as the starting polymer and oxidation-treating said starting polymer in solution in a solvent mixture of water and alcohol in the concomitant presence of hydrogen peroxide and a polyvalent metal salt to provide an oxidation-treated polymer satisfying the relation measured with a different
REFERENCES:
patent: 2541478 (1951-02-01), Nadeau et al.
patent: 3053605 (1962-09-01), Tanabe et al.
patent: 3459724 (1969-08-01), Hartel et al.
patent: 3859269 (1975-01-01), Maurer
patent: 4931500 (1990-06-01), Okamoto et al.
patent: 5164438 (1992-11-01), Umeyama et al.
patent: 5258430 (1993-11-01), Bastioli et al.
patent: 5317052 (1994-05-01), Ohba et al.
Fujita Junko
Miyake Shinji
Takida Hiroshi
Nippon Gohsei Kagaku Kogyo Kabushiki Kaisha
Reddick Judy M.
LandOfFree
Method for producing an oxidation-treated polymer solution and a does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing an oxidation-treated polymer solution and a, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing an oxidation-treated polymer solution and a will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2189333