JPH0765018B2 - 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, films such as agricultural greenhouse cover materials, transparent sheets such as table top materials, and plasticized PVC film materials reinforced with polyester fibers, such as tent film materials, store eaves material, truck hood material, etc. However, as a common problem with these, the stickiness of the surface increases due to the bleeding phenomenon of the plasticizer contained in the plasticized PVC during long-term use, and the contaminants in the air such as dust and oil are increased. However, there is a drawback that the plasticizer that has been contaminated by the bleeding phenomenon has an adverse effect on other materials that are in contact with it, and the PVC itself has poor weather resistance and deteriorates with long-term exposure. is there.

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 product of fluororesin, a blend of polyvinylidene fluoride (PVDF) and polymethylmethacrylate (PMMA) has been proposed (USP3,253,060). It is commercially available and the film obtained from this blend is used for laminating metal plates, plastic plates and the like.

The present inventors also used a graft copolymer of VDF and VAc on a soft fluororesin as a coating resin solution (JP-A-1-185376). Furthermore, a mixed solution of a soft fluororesin solution and a PMMA-based resin solution (JP-A-2-135269) was proposed.

(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 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),
A solution of a soft fluororesin obtained by graft-polymerizing 20 to 80 parts by weight of a vinylidene fluoride monomer with respect to 100 parts by weight of this trunk polymer in a polar solvent, and its glass transition temperature (Tg) is 40 ° C or lower. By using a mixed solution of a polyurethane resin solution, a flexible fluororesin film such as a desired plasticized PVC can be formed.

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.

The unsaturated peroxides used here include unsaturated peroxyesters such as t-butylperoxymethacrylate and t-butylperoxyclonate, and t.
-Unsaturated peroxycarbonates such as butyl peroxyallyl carbonate and P-menthane peroxyallyl carbonate can be exemplified.

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 higher, the viscosity of the solution increases, making it difficult to develop during coating, and at the time of mixing with the polyurethane resin solution described later, the dissolved soft fluororesin will precipitate. Since it causes inconvenience, it is usually about 100 g / l to 200 g / 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 examining the adhesive between the plasticized PVC and the soft fluororesin, obtained a result that a polyurethane-based one is suitable, and actually a polyurethane resin-based adhesive on the plasticized PVC sheet. We succeeded in forming a film with good adhesion by coating it in advance and then coating it with a soft fluororesin solution.In this method, coating of an adhesive layer, drying, coating of a coating liquid,
The drying process was complicated.

Therefore, as a result of studying a blend of a soft fluororesin and a polyurethane resin, the present inventors have shown that the blending with a polyurethane resin having a glass transition temperature (Tg) of 40 ° C. or lower does not impair the flexibility of the soft fluororesin. The present invention has been completed by finding that the intended strong adhesion to other base materials is improved.

When the Tg of the polyurethane resin is 40 ° C or more, when it is used as a surface coating material on a flexible base material, the adhesion and stretchability are poor, and it is impossible to follow repeated bending of the base material, and whitening and peeling phenomena occur. Present.

Here, NN-dimethylformamide (DMF), NN-dimethylacetamide (DMA), N-methylpyrrolidone, 1.3-dimethyl-2-imidazolidinone and the like can be used as the polar solvent that dissolves the soft fluororesin. Considering economy, it is preferable to use DMF and DMA which are general-purpose organic solvents.

Known organic solvents for dissolving the polyurethane resin include ketones, esters, and aromatic hydrocarbons, but those suitable for the present invention include ketones such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK). , Mainly aromatic solvents such as xylene and toluene, and some of chlorinated hydrocarbon and ester solvents are not suitable because they significantly impair the solubility of the soft fluororesin.

Solid content of polyurethane resin solution to be mixed is 10g / l
It is desirable to select in the range of to 300 g / l. When the concentration becomes too high, a tendency that the polyurethane resin partially precipitates when mixed with the polar solvent solution of the soft fluororesin is seen,
On the other hand, in the case of mixing a solution having a low concentration, it is necessary to mix a large amount of solvent in order to contain a predetermined amount of polyurethane resin, which causes a disadvantage that the stability of the soft fluororesin solution is impaired.

Further, the ratio of the polyurethane resin solution to be mixed with the soft fluororesin solution is determined from the ratio of the soft fluororesin and 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 / polyurethane resin in the solution is preferably in the range of 100/5 to 100/70. If the mixture is less than this range, the film obtained by coating will not adhere sufficiently to the intended material such as plasticized PVC, and if it exceeds this range, the chemical resistance and weather resistance of the fluororesin will increase. However, there arises an inconvenience that properties such as antifouling property are significantly deteriorated.

Polyurethane resins useful in the present invention include resins mainly used for adhesives and thermoplastic polyurethane elastomers used for mixing with other resins. There are a one-pack type and a two-pack type for adhesion, and the one-pack type is a solvent solution of a resin having a molecular weight of tens of thousands of a prepolymer having an OH group terminal obtained by a reaction of a polyol and a diisocyanate. Also included are NCO-group-terminated prepolymers that are moisture-curable.

The two-pack type is a mixture of a polyol and a polyisocyanate at the time of use, and examples of the polyol include polyether, polyester polyol, urethane polyol, and the like. Tolylene diisocyanate (TD
There are triisocyanates modified from I), hexamethylene diisocyanate (HDI) and the like. Coronate L, Coronate HL (manufactured by Nippon Polyurethane Co., Ltd.) and the like are used as trade names.

Also, the flexible substrate to be used is preferably one that is compatible with the polyurethane resin to some extent.
Besides, rubber materials such as nitrile rubber and acrylic rubber, and cloth materials made of polyester fibers and the like are exemplified.

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

Experimental Example 1 (A) Manufacture of trunk polymer In a 30-volume stainless steel autoclave, water 15 kg, potassium persulfate 30 g, ammonium perfluorooctanoate 40 g
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 to react. After the completion, the number of rotations of stirring was increased to precipitate the polymer, and a powdery polymer was obtained. 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 2-volume stainless steel autoclave, and after evacuation, 100 g of vinylidene fluoride monomer was charged and 98 ° C.
Graft polymerization was carried out for 22 hours. The generated polymer is separated from the solvent, washed with water, and dried to give a white powder of soft fluororesin.
224 g was obtained.

(C) Dissolution of soft fluororesin 45 g of soft fluororesin obtained by the above graft polymerization was added to 500
Place in a beaker made of stainless steel of ml, add 255 g of NN-dimethylformamide (DMF) and stir for 1 hour with TK homodisper manufactured by Tokushu Kika 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.

The soft fluororesin solution obtained in the above (C) and a one-component polyurethane adhesive (trade name: Nippon Polyurethane Co., Ltd .: Nipporan 3110 (Tg: -30 ° C); solid concentration 23 wt% dissolved in MEK, viscosity 4,800) ~ 6,200cp 25 ℃) weight ratio 100/0
(Comparative Example), 100/3, 100/5, 100/10, 100/25 (above, Example), to produce a mixed solution consisting of 100/50 (Comparative Example),
It was coated on a plasticized PVC / polyester cloth composite membrane material 0.5 mm thick (E-5 manufactured by Kuraray Co., Ltd.).

As for the coating method, the mixed solution was applied on a base cloth by flow coating, the thickness was adjusted with an applicator, and then dried in an oven at 100 ° C. for 10 minutes to obtain a film having a thickness of about 10 μm.

In addition, as a comparative example, the product name: Nippon Polan 3151 (Tg; 55
C.) Coating was carried out in the same manner as in Experimental Example 1 using a solid content concentration of 23 wt% manufactured by Nippon Polyurethane Co., Ltd.

Table 1 shows the properties of the film material obtained by the coating.

In addition, those not coated are also shown as reference examples.

As can be seen from Table 1, the weight ratio of polyurethane resin is 5
The following materials have poor adhesion, and those with a Tg of 40 ° C or higher have poor adhesion and wrinkle recovery.

Experimental Example 2 The soft fluororesin solution obtained in Experimental Example 1 and a commercially available two-component polyester-based polyurethane adhesive (Hitachi Kakei Polymer Co., Ltd. trade name: Hibon 7031L (Tg: 7 ° C); solid content concentration 20 weight %: Viscosity 100 cp 25 ° C.) and a cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L; solid content concentration 75% by weight, viscosity Gardner W to Y) manufactured by changing the mixing ratio, and a plasticizer. As a transparent soft PVC sheet (1mm containing 45 parts by weight of deoctyl phthalate (DOP))
Thickness). The weight ratio of soft fluororesin solution, polyurethane adhesive and crosslinking agent is 100/0/0 (comparative example), 100/10 / 0.5, 100/15 / 0.75, 100/20 / 1.0, 100/25 /
It was adjusted to 1.25 (or more, Example), 100/50 / 2.5, 100/100 / 5.0 (or more, Comparative Example).

The coating method was such that a mixed solution was cast on a PVC sheet, the thickness was adjusted with an applicator, and the coating 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 the coating are compared with those of the second comparative example.
Shown in the table.

It can be seen from Table 2 that when the mixing ratio of the polyurethane is out of the range, the whitening property at the time of folding and the copy transfer property are bad.

Experimental Example 3 100 parts by weight of the soft fluororesin solution prepared in Experimental Example 1 and a mixed solution of various adhesives shown in Table 3 were used to form a transparent soft PVC sheet (1 mm thick) using the same Coronate L as in Experimental Example 2. Coated.

The coating method is 120 after brushing the mixed solution.
It was dried in an oven at ℃ for 20 minutes to obtain a film having a thickness of about 100μ. 180 sheet adhesion obtained by coating
A peel test and a stain resistance test were performed. The results are shown in Table 3.

Contamination resistance test A coating sheet obtained from a mixed solution of a soft fluororesin and various polyurethane resins was used as a 100 mm square test piece,
After putting into a ball mill together with a dirt substance having the following composition, mixing at room temperature for one week, and taking out and evaluating the degree of dirt after washing with water in 5 levels, the results shown in Table 3 were obtained.
The antifouling property of the coating sheet was clearly recognized.

<Stain substance composition> wt% Peat moss 40 Cement 24 Clay 24 Carbon black 1.5 Iron oxide 0.5 Liquid paraffin 10 As can be seen from Table 3, the coating sheet of the present invention has a strong adhesive force against peeling and has stain resistance. Is recognized.

(Effects of the Invention) The fluororesin solution for coating produced according to the present invention has good adhesion to a flexible substrate and can easily form a film that is useful for improving the properties of the substrate. it can.

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. A soft fluororesin prepared by producing a fluorine-containing elastic copolymer (stem polymer) whose (Tg) is below room temperature and graft-polymerizing 20 to 80 parts by weight of vinylidene fluoride monomer to 100 parts by weight of this backbone polymer. Is a solution prepared by mixing a solution obtained by dissolving a polyurethane resin having a glass transition temperature of 40 ° C. or lower in an organic solvent, and a solution in which a soft fluororesin and a polyurethane resin have a weight ratio of 100 / Fluororesin solution for coating which is 5-100 / 70.