JPH052503B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides a base material made of a novel fluorocarbon resin that has elasticity, chemical resistance, stain resistance, light resistance, weather resistance, and non-adhesive properties. Regarding covering materials. (Prior art) Conventional well-known general polyurethane synthetic leather has a texture and appearance that closely resembles natural leather, so it is mainly used for bags, bags, footwear, clothing, etc., which have a relatively short fashion cycle. Furniture, which is often used as a fashionable material and has a long service life.
As an interior material, various proposals have been made to improve surface adhesion, as well as chemical resistance, stain resistance, and weather resistance due to its hydrolyzable property, which causes it to become brittle within a few years. A fluororesin coating has also been proposed. In other words, as a fluororesin film-coated laminate, a method of combining a polyfluorinated vinyl film with a high-strength fabric via a polyurethane layer (Japanese Patent Application Laid-open No.
56-162647), heat-fused polyvinylidene fluoride (Japanese Patent Laid-Open No. 52-69989), or sheets made by heating various resin films above their melting temperature and melting and pasting them onto glass substrates (Japanese Patent Laid-Open No. 61-1999). 61849), and even
Laminations with PVDF, PTFE, PFA, etc. have been proposed. (Problems to be Solved by the Invention) However, although these fluororesins have excellent chemical resistance, weather resistance, and stain resistance, they are inferior in flexibility compared to polyurethane resins, and are also sensitive to organic solvents. Because of its poor solubility, it is difficult to produce a resin solution for molding a casting film in the synthetic leather production process, for example. (Means for Solving the Problems) The present invention has been made to improve the above-mentioned drawbacks, and the fluorine-based coating material coated on the base material through the polyurethane resin contains at least one kind of fluorine-containing material. By copolymerizing a monomer and a monomer having both a double bond and a peroxy bond in the molecule,
A flexible fluorine-containing elastic copolymer (stem polymer) whose glass transition temperature is below room temperature is produced, and 40 to 70 parts by weight of vinylidene fluoride monomer is copolymerized with 100 parts by weight of this backbone polymer. The purpose of the present invention is to provide a coating material made of a fluorocarbon resin. The base materials targeted by the present invention are not particularly limited, but include natural fibers such as cotton, wool, silk, and hemp, recycled fibers such as rayon, viscose, cotton wool, and acetate, or polyester and polyacrylonitrile. , synthetic fibers such as polyvinyl chloride and polyvinylidene chloride alone or mixed fibers, woven fabrics and non-woven fabrics made of inorganic fibers such as glass fibers and asbestos, as well as paper, wood, rubber, plastics, metals, etc. . The urethane resin used as the adhesive layer on the base material in the present invention is a polyester diol obtained by a polycondensation reaction of a polybasic acid such as phthalic acid or adipic acid with a polyhydric hydroxyl compound such as ethylene glycol or diethylene glycol. and −NCO at the terminal obtained from aliphatic diisocyanate.
Polyurethane resin obtained by chain-extending a urethane prepolymer having a group with diamine, or polyether-based polyurethane obtained by reaction with polyoxypropylene glycol, ethylene glycol, tolylene diisocyanate and glycerin,
Any material based on polyurethane resin can be used, such as a crosslinking agent made by reacting ethylene glycol and tolylene diisocyanate with amine-based catalytic diethylethanolamine. Next, the soft fluororesin, which is the most important feature of the present invention, will be explained. The present inventors proposed a method for producing a flexible fluororesin in JP-A-58-206615. From this point of view, new examination and improvement became necessary. The soft fluororesin used is made by copolymerizing one or more monomers including at least one fluorine-containing monomer with a monomer having both a double bond and a peroxy bond in the molecule. A fluorine-containing elastic copolymer (stem polymer) that contains peroxy groups and whose glass transition temperature is below room temperature.
and produce an aqueous emulsion of this stem polymer or
A fluororesin in which 40 to 70 parts by weight of vinylidene fluoride monomer is graft-polymerized to 100 parts by weight of the main polymer in a dispersion solvent, and the resin is N,N-
150g/in organic solvent such as dimethylformamide
The above-mentioned soluble fluororesin, in particular, the backbone polymer in the fluororesin is composed of a fluorine-containing copolymer whose glass transition point temperature is below room temperature. exhibits the properties of an elastic body, and conventional PTFE, PFA, FEP,
It is extremely flexible compared to fluororesins such as ETFE, PCTFE, PVDF, and PVF. The present invention is characterized by the use of such a soft fluororesin, but in order to laminate a thin film (for example, 5 to 25 microns thick) of the resin on the polyurethane synthetic leather surface, a resin solution must be applied. ,
A resin layer obtained by a so-called tearing film molding method, in which a film is formed by evaporating a solvent in a dryer, is applied. The problem with the casting film molding method for fluorine resins is that they have good organic solvent resistance, but the resin solubility is low, and furthermore, the solubility in organic solvents decreases dramatically as the fluorine content in the polymer increases. For this reason, casting film molding is not currently being carried out except for polyvinyl fluoride (PVF). However, PVF is a hard resin and cannot be said to be a good coating material for various base materials that require flexibility. As a concrete example of its application to the base material, the present inventors have improved the stain resistance, chemical resistance, etc., which are problems of polyurethane synthetic leather, while also improving the elastic touch of synthetic leather. As a result of conducting studies on how to maintain the properties of the fluorine resin, it was found that the thin film of the fluorocarbon resin according to the present invention is extremely useful as a synthetic leather coating material. The modification of resins, especially to solvent-soluble resins, has become important. The organic solvents used in the resin solution for forming the casting film are N,N-dimethylformamide (DMF) and methyl ethyl ketone (MEK).
It is common to use mixed solvents such as and toluene (TOL), and among these solvents, DMF was selected as the main compounding solvent for the flexible fluororesin because it has good solubility for the fluororesin. It is desirable that the resin concentration of the solution be at least 150g/, preferably 200g/or more.When forming a film on a casting film forming line, if it is less than 150g/, the amount of solvent evaporated during the film drying process will increase, making it economical. Not on target. As a method for increasing the solubility of soft fluororesins in solvents, the solubility is increased by graft copolymerizing vinylidene fluoride (VDF) monomers with fluorine-containing elastic copolymers (backbone polymers). It has been found. Tetrafluoroethylene monomer, chlorotrifluoroethylene monomer,
With copolymers such as tetrafluoroethylene/ethylene and chlorotrifluoroethylene/ethylene, resin swelling is observed in solvents, but at 150g/ethylene, swelling of the resin is observed.
It was difficult to solubilize any resin having a concentration higher than that. In addition, regarding the influence of the amount of VDF monomer grafted onto the backbone polymer on solubility, the appropriate range is 40 to 70 parts by weight per 100 parts by weight of the backbone polymer, and the solubility test in DMF shows that it is 40 parts by weight or less. If the amount of grafting exceeds 70 parts by weight, it will become gel-like and difficult to dissolve, and if it exceeds 70 parts by weight, the flexibility of the resin's physical properties will decrease and the rubbery properties that are characteristic of soft fluororesins will be lost. It becomes undesirable as a covering material for materials such as synthetic leather. In this way, a soft fluororesin that is soluble in DMF is produced by forming a fluorine-containing elastic copolymer (base polymer) with peroxy bonds in the first stage of the copolymerization reaction.
In the second step reaction, VDF monomers are graft copolymerized in a dispersion solvent of the copolymer obtained in the first step reaction at a temperature below which decomposes peroxy bonds and generates radicals. You can get it. The polymerization conditions of the resin (temperature, stirring number, autoclave capacity, catalyst amount, etc.) affect the degree of polymerization, and the degree of polymerization affects the resin solubility, but since the polymerization reaction is a two-step reaction and is complicated. The range of use of the resin may be selected based on the solubility of the final material, the graft copolymer, in an organic solvent containing DMF as the main ingredient. The unsaturated peroxides used here include t-butyl peroxy methacrylate, t-
Examples include unsaturated peroxyesters such as butylperoxycrotonate, and unsaturated peroxycarbonates such as t-butylperoxyallyl carbonate and P-menthane peroxyallyl carbonate. In addition, as the composition of one or more fluorine-containing monomers, an elastic polymer having a composition of fluorine rubber, a binary system of vinylidene fluoride (VDF) and hexafluoropyropene (HFP), VDF and HFP and tetrafluoroethylene (TFE), and VDF
An example is a monomer composition such as a binary system of and chlorotrifluoroethylene (CTFE). In the present invention, there is no particular restriction on the thickness of the polyurethane resin layer and soft fluororesin applied on the base material, and they are generally used at a thickness of about 0.01 to 1 mm, but they have good weather resistance and antifouling properties. There are no particular restrictions, and the thickness can be made thicker or thinner as long as the objectives of durability and flexibility are achieved. The urethane resin is applied by topping, calendering, coating, or other methods, and necessary plasticizers, stabilizers, colorants, lubricants, etc. may be freely added to the polyurethane resin within the range of customary use. . On the other hand, by adding a coloring agent to the soft fluororesin layer forming the surface layer, and further treating the resin film with surface corona discharge, chemical treatment, etc., it is possible to activate the surface roughness in order to improve adhesive performance. The present invention will be described in detail below with reference to Examples, but is not limited thereto. Examples and Comparative Example 1 Production of backbone polymer 15 kg of pure water, 30 g of potassium persulfate, 40 g of ammonium perfluorooctanoate, and 30 g of t-butylperoxyallyl carbonate were added to a 30-capacity stainless steel autoclave, and after evacuation, the vinylidene fluoride monomer was dissolved. 3.8 kg of chlorotrifluoroethylene monomer and 2.3 kg of chlorotrifluoroethylene monomer were charged, and the polymerization reaction was carried out at a temperature of 51°C for 19 hours with stirring.
At the end of the reaction, the stirring speed 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-butyl peroxyallyl carbonate in the copolymer was determined to be 0.041% by iodometric titration. 2 Production of graft copolymer (Part 1) Stem polymer 144 obtained by the above copolymerization reaction
Put 1,500 g of Freon R113 into a stainless steel autoclave, and after evacuation, add the monomers shown in Table 1, VDF (Example 1), TFE (Comparative Example 1), and ethylene-CTFE (molar ratio of about 1:1). (Comparative Example 2) was charged in an amount of 100 g each, and graft polymerization was carried out at 98° C. for 22 hours. The produced polymer was separated from the solvent, washed with water, and dried to obtain the results shown in Table 1.

[Table] 3 Solubility test (Part 1) 50g of polymer obtained from the above graft copolymerization
Place each in a 300 ml beaker and add 225 ml of N,N-dimethylformamide (DMF, first grade reagent).
was added, stirred for 20 minutes using a laboratory disperser manufactured by Mitamura Riken Kogyo Co., Ltd., and allowed to stand overnight at room temperature, then 25 ml of methyl ethyl ketone was added, stirred again using a laboratory disperser for 5 minutes, and then allowed to stand. The properties of the polymer solution were observed and the viscosity was measured. The results are shown in Table 2.

[Table] According to the above results, the VDF graft copolymer was dissolved, but the TFE and E-CTFE copolymers were not dissolved and were unsuitable as resins for casting film molding. 4 Production of graft copolymer (Part 2) Stem polymer obtained by the above copolymer reaction
144 g and 1500 g of Freon R113 were placed in a stainless steel autoclave, and after evacuation, VDF monomer was charged in varying amounts as shown in Table 3, and graft polymerization was carried out at 98°C for 22 hours. The produced polymer was separated from the solvent, washed with water, and dried to obtain the results shown in the table below.

[Table] Increase in amount 5 Solubility test and shear modulus measurement For the polymer obtained with the VDF graft copolymer, the properties of the solution were observed using the solubility test method described above, and using a B-type viscometer. , the viscosity at 25°C was measured. In addition, after masticating the VDF graft copolymer with a heated roll, a 1 mm thick sheet was formed using a heated press, and a torsional free damping type viscoelasticity measuring device (Model RD-1100AD manufactured by Resca, test piece size, 8 cm ×
The shear modulus at 30°C was measured at 1 cm x 1 mm thick). The results are shown in Table 4.

[Table] Reference values.
From the above results, if the amount of VDF grafted to 100 parts by weight of the main polymer is less than 40 parts by weight, there will be a problem in creating a polymer solution, while if it exceeds 70 parts by weight, the shear modulus of the polymer will increase. Because the film becomes hard, it is not preferable to use it as a surface material for synthetic leather. In addition, as a result of measuring the shear modulus of commercially available PVDF resin (manufactured by Pennwalt) and PTFE resin (manufactured by Daikin), the measured value at 30°C was: PVDF 8 × 10 ⁹ dyne/cm ² PTFE 2 × 10 ⁹ dyne/cm ² , and PVDF and PTFE are harder resins than the soft fluororesin, and are not preferred as synthetic leather covering materials. 6. Preparation of synthetic leather The solution of Example 3 prepared in the above solubility test (54 parts by weight of VDF graft, concentration 200 g/) was applied onto a polypropylene release paper with the composition shown in Table 5 Example. It was dried for 1 minute at °C to form a surface layer (10 μm) with a solid content of 20 g/m ² . Next, an adhesive made of a two-component polyurethane resin having the composition shown in Table 5 was applied and dried at 80°C for 1 minute to form a polyurethane adhesive layer (20 μm) with a solid content coverage of 40 g/m ² . Immediately adhere to a cloth base material (1 mm) and leave at room temperature.
It was aged for 24 hours. Thereafter, the release paper was peeled off to create a fluororesin-coated synthetic leather. In addition, as a comparative example, polyurethane synthetic leather was created using the same processing specifications. The composition specifications are shown in Table 5, and the results of the evaluation test are shown in Table 6. 7 Test method for synthetic leather (1) Light resistance test Tested in accordance with JISA-6921 "Wallpaper". (2) NO _x test Sodium nitrite 0.4g Dilute sulfuric acid 10ml A sample of any size was pasted on the inner wall of a desiccator, the above chemicals were placed in a watch glass, the lid of the desiccator was closed, and after 10 minutes the sample was taken out and evaluated. . The evaluation method is a 5-level scale, with 5 being the highest value. (3) Chemical resistance and stain resistance test Approximately 1.0 to 1.5 ml of each test solution (dropped solution) was dropped onto synthetic leather held horizontally. After 24 hours, wiped with a compress and dried. The operation of dropping the liquid on the same spot was repeated 7 times and visually observed, and the results were evaluated as ○ with no change, △ with faint colored contamination, and × with obvious colored contamination.
And so. (4) Texture was evaluated based on the feel against the skin, and ○ means excellent. (5) No change in washability was rated as ○.

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Claims (1)

[Claims] 1. The fluororesin coated on the substrate material via a polyurethane resin layer contains at least one kind of monomer containing at least one kind of fluorine-containing monomer and a monomer having both a double bond and a peroxy bond in the molecule. A fluorine-containing elastic copolymer (stem polymer) whose glass transition temperature is below room temperature is produced by copolymerizing the vinylidene fluoride monomer with 100 parts by weight of the backbone polymer. A coating material made of a soft fluororesin grafted with 40 to 70 parts by weight.