JPH0762121B2 - Fluororesin solution for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a novel fluororesin solution for coating, which has flexibility with stretchability, chemical resistance, stain resistance, weather resistance and tack-free property. The present invention relates to surface modification of flexible materials such as plasticized vinyl chloride resin.

(Prior Art) Conventionally, plasticized vinyl chloride (PVC) has been used for various purposes. For example, in the case of films such as greenhouse cover materials for agriculture, in transparent sheets table top materials, and in the form of plasticized PVC membrane materials reinforced with polyester fibers,
It is used for tent film material, store fart film material, truck hood film material, etc., but as a common problem with these is the adhesion of the surface due to the bleeding phenomenon of the plasticizer contained in plasticized PVC during long-term use. However, there is a drawback that the plasticizer, which is polluted by the bleeding phenomenon, adversely affects other materials that are in contact with it. It also has the drawback of poor weather resistance and deterioration over long-term exposure.

Therefore, coating with a fluororesin has been proposed as one of these measures for improvement. Fluororesin generally has chemical resistance,
Since it is excellent in weather resistance, stain resistance and non-adhesiveness, it is a resin suitable for improving the above defects. As a conventional fluororesin film-coated laminate, a method in which a polyvinyl fluoride film is combined with a high-strength woven fabric via a polyurethane layer (JP-A-56-162647), and polyvinylidene fluoride by heat fusion (JP-A-52-69989). ) Or a sheet obtained by melting and bonding various fluororesin films (Japanese Patent Laid-Open No. 61-61849), and further lamination with PVDF, PTFE, PFA, etc. has been proposed.

As a modified fluororesin, a blend of poly (vinylidene fluoride) (PVDF) and polymethylmethacrylate (PMMA) has been proposed (USP3,253,060), and this blend is dispersed in a solvent and sold as a baking coating. The film obtained from this blend is a metal plate,
It is used for laminating plastic plates.

(Problems to be Solved by the Invention) Although a conventionally proposed coating method using a fluororesin can form a layer excellent in stain resistance, chemical resistance, weather resistance and the like on the surface of a base material. Plasticization as intended by the present invention
It lacks flexibility and flexibility as a surface coating material for flexible substrates such as PVC and various rubbers. For example, when a polyvinyl fluoride film is used as the covering material for the tent film material, the folding wrinkles of the sheet before the tent construction may remain after the construction, so it is a surface material that can follow the bendability of the sheet material. Absent.

One of the problems to be solved by the present invention is to provide a fluororesin wave coating material excellent in such flexibility and flexibility.

Further, as a method for forming the fluororesin surface layer, there is a method by laminating a fluororesin film or a method in which a fluororesin solution or a fluororesin dispersion is directly coated on a substrate and then dried, heat-treated or the like to form a film. However, fluororesins generally have poor adhesion to other materials, and any of these methods require complicated steps such as film surface treatment, substrate primer treatment, use of adhesives, and heat treatment at high temperatures.

The present invention provides a fluororesin coating solution to which a simple method of directly coating a flexible base material and evaporating a solvent at a relatively low temperature can be applied when forming a fluororesin film.

(Means for Solving Problems) The present invention has been made to improve the above problems,
One or more monomers containing at least one or more fluorine-containing monomers and a monomer having a double bond and a peroxy bond at the same time in the molecule are copolymerized, and the glass transition temperature is room temperature or lower. Manufactures a copolymer (trunk polymer),
By using a mixed solution of a solution of a soft fluororesin obtained by graft-polymerizing a vinylidene fluoride monomer with respect to 100 parts by weight of this trunk polymer in a polar solvent in a proportion of 20 to 80 parts by weight, and a methyl methacrylate resin solution. Plasticization
It is capable of forming a highly flexible fluororesin film such as PVC.

Regarding the production method of these soft fluororesins, the present inventors have
As disclosed in Japanese Examined Patent Publication No. 62-34324, as the resin used in the coating solution of the present invention, vinylidene fluoride is used as the trunk polymer in consideration of its solubility, weather resistance, antifouling property, etc. A graft-copolymerized product is suitable, and the proportion thereof is preferably a graft-polymerized product of 20 to 80 parts by weight of vinylidene fluoride monomer with respect to 100 parts by weight of the trunk polymer.

If the amount of vinylidene fluoride is less than this range, the strength of the coating film formed by the coating will be weak and there will be the inconvenience of breaking during bending, and if it is more than this range, the flexibility of the target coating film will be lost.

Examples of unsaturated peroxides used here include unsaturated peroxyesters such as t-butylperoxymethacrylate and t-butylperoxycrotonate, and unsaturated peroxycarbonates such as t-butylperoxyallylcarbonate and P-menthaneperoxyallylcarbonate. Can be illustrated.

Further, as the composition of one or more of the fluorine-containing monomers, an elastic polymer having a composition of fluororubber, a binary system of vinylidene fluoride (VDF) and hexafluoroviropene (HFP), VD
Examples thereof include a ternary system of F, HFP and tetrafluoroethylene (TFE), and a binary system of VDF and chlorotrifluoroethylene (CTFE).

Further, the resin concentration of the solution is at most 300 g / l or less, preferably 200 g / l or less. At 300 g / l or more, the viscosity of the solution increases, making it difficult to develop during coating.In addition, the dissolved soft fluororesin will precipitate during mixing with the methyl methacrylate resin solution described later. In general, 100g / l ~ 200g
It is about / l.

It is possible to form a flexible fluororesin film on a substrate by coating the soft fluororesin solution alone and drying and volatilizing the solvent.
It is difficult to put into practical use because it lacks flexibility such as C and adhesion to other materials.

The present inventors, as a result of studying the adhesive between the plasticized PVC and the soft fluororesin, obtained a result that a methyl methacrylate resin-based one and a urethane-based one are suitable, and actually the methacrylic resin on the plasticized PVC sheet is obtained. Succeeded to form a film having good adhesiveness by pre-applying an acid methyl resin-based adhesive and then coating with a soft fluororesin solution, but with this method, application of an adhesive layer, drying,
Furthermore, not only the process of coating and drying the coating solution becomes complicated, but also the whitening phenomenon occurs due to the adhesive layer being hard when the laminate is bent, and the whitening phenomenon remains even after the bending is released. occured.

Therefore, the present inventors next examined the modification by blending a soft fluororesin and a methyl methacrylate resin, and the pellets obtained by previously hot-melt mixing both resins with an extruder are polar solvents. It was difficult to completely dissolve it in, and some swollen particles remained undissolved.

This is because the soft fluororesin has a limited solubility parameter and is soluble only in highly polar organic solvents,
On the other hand, the methyl methacrylate resin has the contradictory property that it is rather insoluble in these polar solvents, and that the soft fluororesin such as ketone, ester and aromatic is easily soluble in the insoluble solvent. This is presumed to be the cause.

Then, as a result of diligent studies on the solubility of the soft fluororesin in various solvents as shown in Table 1, the present inventors have found that both resins are blended by a method of blending a polar solvent solution of the soft fluororesin with a methyl methacrylate resin solution. The present invention has been completed by finding that a completely dissolved solution can be produced.

As a polar solvent that dissolves this soft fluororesin, NN
-Dimethylformamide (DMF), NN-dimethylacetamide (DMA), N-methylpyrrolidone, 1.3-dimethyl-2-imidazolidinone, etc. can be used, but in view of economy, use of general-purpose organic solvents DMF and DMA Is desirable.

Further, as the organic solvent for dissolving the methyl methacrylate resin, ketones, esters, aromatic hydrocarbons, chlorinated hydrocarbons, etc. are known, but those suitable for the present invention are methyl ethyl ketone, methyl isobutyl ketone, etc. , Mainly aromatic solvents such as ketone type, xylene and toluene, and ether type solvents such as tetrahydrofuran and 1.4-dioxane, and some of the chlorinated hydrocarbon type and ester type solvents dissolve soft fluororesin. It is not suitable because it significantly impairs sex.

The ratio of the methyl methacrylate resin solution to be mixed with these soft fluororesin solutions depends on the ratio of the soft fluororesin to the methyl methacrylate resin in the film finally obtained and the solvent ratio which does not impair the dissolution stability of the soft fluororesin solution. Although it is determined, the weight ratio of soft fluororesin / methyl methacrylate resin in the solution is preferably in the range of 100/5 to 100/50. In the case of a mixture below this range, the film obtained by coating does not sufficiently adhere to the desired material such as plasticized PVC, and when it exceeds this range, the desired flexibility and fluororesin have. There arises a disadvantage that properties such as chemical resistance, weather resistance and antifouling property are remarkably deteriorated.

The solid content concentration of the mixed methyl methacrylate resin solution is 50.
It is desirable to select in the range of g / l to 500 g / l. When the concentration is too high, it tends to partially precipitate the methyl methacrylate resin when mixed with the polar solvent solution of the soft fluororesin, while when mixing the solution with a low concentration, a predetermined amount of methyl methacrylate resin is used. In order to contain it, it is necessary to mix a large amount of solvent, which causes a disadvantage that the stability of the soft fluororesin solution is impaired.

Methyl methacrylate resins useful in the present invention include methyl methacrylate homopolymers and copolymers of methyl methacrylate and other unsaturated monomers (preferably copolymerization ratios of other unsaturated monomers. Is 25 mol% or less), and examples of the copolymerizable monomer include methyl acrylate, methyl (meth) acrylate, (propyl methacrylate, butyl (meth) acrylate, and cyclo (meth) acrylate. Kicil,
Examples thereof include hydroxyethyl (meth) acrylate, (meth) acrylic glycisol, styrene, α-methylstyrene, and methacrylic acid.

The mixed solution obtained by the present invention is coated on a flexible material such as plasticized PVC, and then the solvent is volatilized at a temperature of 50 to 150 ° C. to form a film having a high flexibility and a high adhesion on the substrate. Can be formed.

The target flexible material is preferably one that is compatible with methyl methacrylate to some extent, and examples thereof include rubber materials such as nitrile rubber and acrylic rubber in addition to plasticized PVC, and cloth materials such as polyester fibers.

Hereinafter, examples, comparative examples and reference examples of the present invention will be specifically described.

Experimental Example 1 (A) Production of trunk polymer In a stainless steel autoclave having a volume of 30 l, 15 kg of water, 30 g of potassium persulfate, and 40 g of ammonium perfluorooctanoate.
And 30 g of t-butylperoxyallyl carbonate are added, and after evacuation, 3.8 kg of vinylidene fluoride monomer and 2.3 kg of chlorotrifluoroethylene monomer are charged, and the polymerization reaction is carried out at a temperature of 51 ° C. for 19 hours while stirring. At the end of the process, the number of rotations of stirring was increased to precipitate the polymer to obtain a powdery polymer. The yield after washing with water and drying was 5.0 kg, and the amount of active oxygen based on t-butylheroxyallyl carbonate in the copolymer was determined to be 0.041% by the iodometric titration method.

(B) Production of graft polymer 144 g of the trunk polymer obtained by the above copolymerization reaction and Freon R1
13 1500 g was charged into a stainless steel autoclave with a capacity of 2 liters, and after evacuation, 100 g of vinylidene fluoride monomer was charged and at 98 ° C
Graft polymerization was carried out for 22 hours. After the generated polymer is separated from the solvent, washed with water and dried to give a white powder of soft fluororesin 22
I got 4g.

(C) Dissolution of soft fluororesin 45 g of soft fluororesin obtained by the above graft polymerization was added to 500
Add to a 100 ml beaker made of stainless steel, add 255 g of NN-dimethylformamide (DMF) and stir for 1 hour with TK homodisper manufactured by Tokushu Koka Kogyo Co., Ltd. while heating to 50 ° C.
Then, cool it to room temperature by allowing it to cool, and soft DM of DM
An F solution was obtained.

The viscosity of this solution at 25 ° C. was measured with a B-type viscometer to be 3000 cp.

(D) Methyl methacrylate resin solution Methyl methacrylate resin (PMMA) Mitsubishi Rayon Co., Ltd.
Acrypet MD) pellets (30 g) were placed in a 500 ml stainless beaker, methyl ethyl ketone (MEK) (270 g) was added, and the mixture was stirred to obtain a solution having a viscosity of 400 cp at 25 ° C.

The ratio of the soft fluororesin solution obtained in the above (C) to the PMMA solution obtained in the above (D) was 100/0 by weight ratio. Comparative Examples, 100/10, 100
/ 20, 100/30, 100/70 (hereinafter, examples), 100/100 (comparative examples) to produce a mixed solution, and plasticized PVC / polyester cloth composite membrane material 0.5 mm thick (Kuraray Co., Ltd.) E-5).

The coating method is to cast the mixed solution on the base cloth,
After adjusting the thickness with an applicator, in an oven at 80 ° C
After drying for 20 minutes, a film having a thickness of about 10 μm was obtained. The properties of the film material obtained by coating are shown in Table 2 together with reference examples.

Experimental Example 2 The soft fluororesin solution obtained in Experimental Example 1 and a commercially available methyl methacrylate resin adhesive (manufactured by Sony Chemical Co., Ltd.)
SC-462, solid concentration 29-31% by weight, viscosity 300 cp (25
)) Was prepared by changing the mixing ratio and coated on a transparent PVC sheet (1 mm thick) containing 45 parts by weight of deoctyl phthalate (DOP) as a plasticizer. The ratio of soft fluororesin solution and methyl methacrylate adhesive is
100/0 (Comparative example), 100/10, 100/15, 100/20, 100/25
(Above, example), 100/50, 100/100 (above, comparative example)
Adjusted to. The coating method is to apply the mixed solution on a PVC sheet by coating and adjust the thickness with an applicator,
It was dried in an oven at 100 ° C. for 5 minutes to obtain a film having a thickness of about 20 μm. The properties of the sheet obtained by coating are shown in Table 3 together with a reference example.

Experimental Example 3 100 parts by weight of the soft fluororesin solution prepared in Experimental Example 1 and PMM
A mixed solution of 20 parts by weight of the solution A was coated on a 1 mm thick nitrile rubber (NBR) bleeding sheet having a standard composition defined in JIS K6384. The coating method was applied by brushing the mixed solution and then dried in an oven at 100 ° C. for 5 minutes to obtain a film having a thickness of about 70 μm. The properties of the sheet obtained by coating are shown in Table 4 together with Comparative Examples.

As can be seen from Table 4, the adhesive strength is strong and the corrosion resistance in fuel oil is improved.

(Effect of the invention) The fluororesin solution for coating produced by the present invention has good adhesion to a flexible material and is suitable for easily forming a film useful for improving the properties of the material. is there.

Claims (1)

[Claims] 1. A glass transition temperature obtained by copolymerizing at least one monomer containing at least one fluorine-containing monomer with a monomer having a double bond and a peroxy bond at the same time in the molecule. Is a room temperature or lower, and a fluorine-containing elastic copolymer (stem polymer) is manufactured, and a soft fluororesin obtained by graft-polymerizing 20 to 80 parts by weight of vinylidene fluoride monomer to 100 parts by weight of this trunk polymer is a polar solvent. For coating, which is a solution prepared by mixing a solution in which the methyl methacrylate resin is dissolved in an organic solvent, wherein the weight ratio of the soft fluororesin to the methyl methacrylate resin is 100/5 to 100/50. Fluororesin solution.