JPS6128512B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyvinyl chloride film for agricultural use. Specifically, it relates to surface treatment of agricultural polyvinyl chloride film, and one of its features is that by adding an acid component to the surface treatment agent, it provides a surface treatment technology that has unprecedented strong adhesion to the surface of the film. It is something. More specifically, agricultural polyvinyl chloride film is coated with a surface treatment agent consisting of an acrylic copolymer, cellulose acetate butyrate, acid, and a solvent to form a surface treatment film that has strong adhesion to the film. It is also a long-life agricultural polyester that is durable, with few cracks and scratches caused by bending, stretching, and friction, and prevents dust from adhering to the surface-treated surface, and reduces light transmittance over time. The purpose is to provide vinyl chloride film. Currently, films or plates made of glass and polymeric materials are widely used as agricultural covering materials. The first purpose of using covering materials is to retain heat and to perform forced cultivation of agricultural products. As this type of polymeric material, polyvinyl chloride, polyethylene, ethylene copolymers, acrylic polymers, etc. are used in the form of films or plates. Among these materials, polyvinyl chloride film is most commonly used because of its effect on forced cultivation of agricultural crops and its economic efficiency. The primary purpose of agricultural covering materials is heat retention, but they are also required to have the effect of providing the environmental conditions necessary for the growth of agricultural crops. For example, it is said that the film has a high light transmittance, but for this purpose, there is less dust adhesion and less deterioration of the film. Since agricultural covering materials are exposed outdoors and used under harsh conditions, the film itself deteriorates over time. However, due to economic factors such as the recent rise in the price of materials and the rise in installation costs for greenhouses, etc., there is a strong desire to extend the lifespan of covering materials. Satisfying this demand will not only extend the life of the film, but will also save resources, save energy, and reduce pollution problems associated with film disposal. When agricultural polyvinyl chloride film is used outdoors, it is exposed to harsh conditions such as temperature differences between day and night, humidity differences, temperature differences inside and outside the greenhouse, humidity differences, rainfall, and sunlight, so it becomes plastic over time. agent, stabilizer,
Other additives migrate to the surface, dust adheres to the surface, and resin deterioration progresses, resulting in film deterioration. As the film deteriorates, it becomes opaque and brittle. It is generally known that such deteriorated films have low light transmittance and are prone to accidents such as tearing due to wind and rain. In addition, conventional methods of surface treatment of agricultural polyvinyl chloride film to prevent plasticizers, stabilizers, and other additives from migrating to the surface and prevent deterioration have already been used for some products. However, in this type of technology that has been used conventionally, the surface treatment agent is a solution of an acrylic copolymer containing methyl methacrylate as a main component. Comonomers other than methyl methacrylate include monomers having carboxyl groups, hydroxyl groups, amide groups, etc. for the purpose of improving adhesion or preventing migration of plasticizers, stabilizers, etc., and monomers that soften the resulting film. It is made of acrylic ester monomer. Furthermore, one major field of plasticized polyvinyl chloride products is polyvinyl chloride leather, and most of the polyvinyl chloride leather products are surface-treated. Treatment agents for agricultural polyvinyl chloride film are used to protect the film, while treatment agents for polyvinyl chloride leather have more purposes, such as preventing adhesion, adjusting the texture and texture of the surface, It is used to adjust gloss, etc., and has a strong cosmetic element in addition to protecting the film. Agricultural vinyl chloride film and polyvinyl chloride leather are both made of polyvinyl chloride containing a plasticizer, but there is a big difference in the composition of the surface treatment agent used. Known agricultural polyvinyl chloride film processing agents are basically those in which an acrylic copolymer is dissolved in a solvent, and the solvent composition is mainly composed of a non-solvent for polyvinyl chloride. On the other hand, PVC leather treatment agents cannot obtain sufficient physical properties with acrylic copolymers alone, so acrylic copolymers alone are rarely used, and other polymers and various additives are not used. added,
The solvent composition is mainly methyl ethyl ketone, and tetrahydrofuran, cyclohexanone, methyl isobutyl ketone, toluene which is a non-solvent for polyvinyl chloride, and ester solvents are used. The difference in the solvent used for both surface treatment agents is due to the structural structure of the object to be coated, but polyvinyl chloride leather has a cloth or the like adhered to the back side as a support. Therefore, a large amount of a solvent for polyvinyl chloride can be used as a solvent for the surface treatment agent. In contrast, agricultural polyvinyl chloride film does not have a support and has a film thickness of approximately 0.1 mm. Therefore, if the solvent of the surface treatment agent contains a large amount of polyvinyl chloride solvate, the product will swell and curl, making it difficult to maintain the homogeneity of the product. For this purpose, the solvent must be composed mainly of a non-solvent of so-called polyvinyl chloride. Such a difference in the composition of the two solvents poses a major restriction in terms of the type of resin that can be used for film formation in the surface treatment agent for agricultural polyvinyl chloride films. This is considered to be a major impediment to the improvement in the properties of the surface treated film of agricultural polyvinyl chloride film. Now, when comparing the surface treatment films of commercially available dust-proof agricultural polyvinyl chloride films and vinyl chloride leather, the following can generally be said. A drawback of the surface-treated film of dust-proof agricultural polyvinyl chloride film is that it has poor adhesion. Cracks are likely to occur due to bending and stretching. Poor abrasion resistance. It can be summarized in three points. Regarding adhesion, static initial adhesion tests are good. However, after being subjected to conditions such as those used in actual use, such as bending, stretching, and immersion in water, it is easily peeled off in the Sellotape test. With regard to the occurrence of cracks due to bending and stretching, cracks are likely to occur particularly during bending and stretching under low temperature conditions. Regarding its abrasion resistance, it easily scratches when rubbed against the surface with cotton cloth or the like. The above-mentioned drawbacks occur when agricultural polyvinyl chloride film is applied to greenhouses, etc., or under the conditions in which it is actually used. If the surface-treated protective film peels or cracks, the affected area will become plastic. It is clear that agents, stabilizers, etc. easily migrate to the surface and the deterioration of polyvinyl chloride progresses more easily. As a result of a detailed comparative study of surface treatment agents for agricultural polyvinyl chloride film and surface treatment agents for vinyl chloride leather, the present invention found that the disadvantages of surface treatment agents for agricultural polyvinyl chloride film are poor adhesion. It can be inferred that this is due to the use of an acrylic copolymer alone, and by improving this drawback, a polyvinyl chloride film for agricultural use that can be used as a truly practical product and is highly profitable compared to conventional products has been completed. It is what was done. The stem fat composition of the surface treatment agent of the present invention consists of an acrylic copolymer mainly composed of methyl methacrylate and cellulose acetate butyrate. It has been found that even when cellulose acetate butyrate is mixed and used, the resulting film has very good transparency and has good properties as a surface treatment film. However, even in such a resin composition, sufficient adhesion may not be obtained if the solvent composition is toluene, ethyl acetate, isobrobanol, etc., which are non-solvents for polyvinyl chloride, alone or in combination. This is caused by additives contained in agricultural polyvinyl chloride film. Conventional surface treatment agents for polyvinyl chloride films, including agricultural polyvinyl chloride films, contain ketones,
It was generally considered that polyvinyl chloride solvents such as tetrahydrofuran should not be used. However, it has been found that when these solvents are partially used in combination with non-solvents, adhesion is improved without causing the coating defects that occur when solvents are used. A significant effect was also observed in that the viscosity of the treatment agent solution was reduced and the coating suitability was improved. However, agricultural polyvinyl chloride films are affected by additives such as antifogging agents, and there are cases where the adhesion is still insufficient. For these reasons, various additives were investigated with the aim of improving adhesion. It was discovered that adding a small amount of an acidic substance such as an organic acid or an inorganic acid to a surface treatment agent dramatically improves the adhesion of the surface treatment film. Although the addition of the acid depends on the amount used, it does not reduce the properties required for the surface treatment agent film such as transparency, light resistance, migration prevention effect of various additives, and non-adhesiveness over time. There was little deterioration, and high-frequency adhesion during film processing was also good. Acid, which is one of the essential components of the present invention, greatly improves the adhesion of the surface treatment film. The acid that improves adhesiveness may be either an inorganic acid or an organic acid,
Examples of inorganic acids include hydrochloric acid, sulfuric acid, phosphoric acid, hypophosphorous acid, and nitric acid, but phosphoric acid, hypophosphorous acid, and the like are preferable because they may cause corrosion to containers and coating equipment during storage. Examples of organic acids include para-toluenesulfonic acid, maleic acid, fumaric acid, and phthalic acid. It is preferable that the amount used is as small as possible within a range that satisfies the adhesion to the film. It is usually 0.1 to 1.0 parts by weight per 100 parts by weight of the resin component. If the amount of acid used is below 0.1 parts by weight,
If the heating and drying conditions after coating are insufficient, adhesiveness may be insufficient, so at least 0.1 part by weight is required. Further, even if 1.0 parts by weight or more is used, the adhesiveness will not be further improved. The most preferred range of acid usage is 0.2 to 0.5 parts by weight. It is undesirable to use an extremely large amount of acid because it may accelerate the deterioration of polyvinyl chloride. Furthermore, if a large amount of acid is used, the agricultural polyvinyl chloride film may become cloudy when wetted when actually used in greenhouses, which is also undesirable from this point of view. After the acid added in this manner is applied as an agricultural polyvinyl chloride film, it is washed away by rainwater and moisture adhering to the surface. Furthermore, the amount of ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and tetrahydrofuran used in the mixed solvent component, which is one of the essential components of the present invention, is greater than that of toluene, esters, and alcohols, which are non-solvents for polyvinyl chloride. It is blended in an amount of 5 to 20 parts by weight to 80 to 95 parts by weight of either one or a mixture thereof. If the amount of these solvents used exceeds 20 parts by weight, the agricultural vinyl film will swell and curl due to the solvent during the coating process with the surface treatment agent, making it impossible to finish a good product. Furthermore, if the amount of the solvent is less than 5 parts by weight, it will hardly contribute to improving the adhesiveness. In addition, cellulose acetate butyrate, one of the resin components of the present invention, has poor solubility in toluene, etc., so the surface treatment agent may take on a gel-like state in winter, and the solubility of the resin component It is an essential component to improve coating properties and coatability. Furthermore, the acrylic copolymer, which is one of the essential components of the present invention, has methyl methacrylate as its main component, and contains acrylic esters, long-chain alkyl methacrylic esters, plasticizers, stabilizers, etc. as soft components to adjust hardness. A monomer having a hydroxyl group, an amide group, a carboxyl group, etc. can be used in combination for the purpose of preventing migration of . If the amount of these monomers having polar groups increases, the adhesion and water resistance will deteriorate, so the amount of the monomer used is naturally limited. Acrylic polymers are obtained by solution polymerization using conventional methods. Furthermore, cellulose acetate butyrate, which is one of the essential components of the present invention, has good compatibility with the acrylic copolymer and provides a transparent film. Agricultural polyvinyl chloride films coated with a surface treatment agent consisting of an acrylic copolymer alone are susceptible to cracks and scratches in the surface treatment film due to bending, stretching, or friction. However, the surface treated film containing the cellulose acetate butyrate of the present invention has fewer cracks and scratches caused by bending, stretching and friction. Another effect was that the adhesiveness of the surface was reduced, resulting in less dust adhesion. The amount of cellulose acetate butyrate used is 5 to 50 parts by weight based on 100 parts by weight of the total resin content. The amount of cellulose acetate butyrate used is 5
If the amount is less than 1 part by weight, almost no effect is observed. Moreover, if the amount used is 50 parts by weight or more, the adhesiveness when wet tends to decrease, which is not preferable. In addition, it is currently unfavorable from the economic point of view, such as the cost of raw materials. The preferred range of use of cellulose acetate butyrate is 10 to 40 parts by weight. The surface treatment agent of the present invention is produced by polymerizing an acrylic copolymer using a conventional method, diluting it with a solvent if necessary, and adding cellulose acetate butyrate in the form of a solution or powder to form a uniform solution. is given by inputting . Specific comparative examples of the present invention will be shown below. First, a 15% concentration surface treatment agent was prepared using an acrylic copolymer consisting of 82 parts of methyl methacrylate, 15 parts of ethyl acrylate, and 3 parts of methacrylic acid, cellulose acetate butyrate (CAB), phosphoric acid, and a solvent. Agricultural polyvinyl chloride film is a water-free film that has not been subjected to surface treatment, and is coated with the surface treatment agent of the present invention using a No. 0.2 bar coater, dried at 80°C for 1 minute, and then placed indoors at 24°C. This was left to stand for a period of time to produce the agricultural polyvinyl chloride film of the present invention, which was then used for testing. The test results are shown in Table 1. The contents of the comparative examples in the table are as follows.

【table】

[Table] Comparative Example 1 in Table 1: Agricultural polyvinyl chloride film with untreated surface. Comparative Example 2: The film of Comparative Example 1 (hereinafter referred to as film) was coated with an acrylic copolymer, which has been conventionally known as a surface treatment agent for agricultural and vegetable films. Comparative Example 3: A film was coated with the processing agent of Comparative Example 2 to which methyl ethyl ketone (hereinafter referred to as MEK) was added. Comparative Example 4: A film was coated with the processing agent of Comparative Example 3 to which an acid was added. Comparative Example 5: A film was coated with the processing agent of Comparative Example 2 plus CAB. Comparative Example 6: A film was coated with the processing agent of Comparative Example 5 to which MEK was added. Comparative Example 7: A film was coated with the processing agent of Comparative Example 5 to which an acid was added. Comparative Example 8: A film was coated with the processing agent of Comparative Example 7 in which MEK was added. The evaluation in the table was based on the following criteria. A; Very good B; Good C; Slightly inferior but still usable D; Poor properties and problems in use E; Poor properties and unusable Table 1 To summarize the results, it was shown that the addition of CAB has an excellent effect on improving surface tackiness.
This has been proven to be effective in preventing surface contamination. It has been clearly demonstrated that the addition of acid has the most significant effect on improving adhesion, and it is also found that it is effective in preventing bending/stretching deterioration. It is shown that the addition of a solvent-philic agent contributes to improvements in adhesion, coatability, and transparency. Furthermore, the effect of the combination of the above three components under actually used humid conditions is clearly shown in the adhesion after immersion in water, and the present invention is based on the discovery of the combined effect of the three components of acid, solvent, and CAB. The details of how it was completed will be revealed. Examples will be described below to explain the present invention in detail. Example 1 Methyl methacrylate 160 parts by weight Methyl acrylate 40 Azobisisobutyronitrile 1 Toluene 240 Isopropyl alcohol 60 The above mixture was polymerized at reflux temperature for 6 hours. Add 0.4 parts by weight of azobisisobutyronitrile at the beginning, then add 0.2 parts by weight every hour from the start of polymerization.
0.2 part by weight was added 8 times. Acrylic copolymer solution obtained above 225 parts Cellulose acetate butyrate (Eastman Chemical Company HSB) 60 Ethyl acetate 200 Isopropyl alcohol 220 Methyl ethyl ketone 135 Paratoluenesulfonic acid 0.6 The above mixture was uniformly dissolved to obtain a surface treatment agent. . The obtained surface treatment agent was mixed with 100 parts by weight of polyvinyl chloride resin (average degree of polymerization 1300), 50 parts by weight of dioctyl phthalate, 3 parts by weight of barium and zinc stearate, 2 parts by weight of epoxidized soybean oil, and ethylene bisstearyl. Anhydrous polyvinyl chloride film for agricultural use manufactured to a thickness of 0.1 m/m by a calendar method with a blend of 0.5 parts by weight of amide and ² parts by weight of sorbitan monostearate was coated at a rate of 15 g/m2. A surface-treated agricultural polyvinyl chloride film was obtained. Example 2 Methyl methacrylate 80 parts by weight Hydroxyethyl acrylate 4 Ethyl acrylate 16 Cumene hydroperoxide 0.5 Toluene 85 Butanol 15 The above mixture was polymerized at reflux temperature for 8 hours. Acrylic copolymer solution obtained above 450 parts by weight Cellulose acetate butyrate 20 parts by weight Ethyl acetate 200〃 Isopropyl alcohol 280〃 Methyl isobutyl ketone 50〃 Phosphoric acid (85% concentration) 1.2〃 Dissolve the above mixture uniformly and treat the surface obtained the drug. The obtained surface treatment agent was coated on the film produced in Example 1 to obtain a surface treated agricultural polyvinyl chloride film. Example 3 Acrylic copolymer solution obtained in Example 2 350 parts by weight Cellulose acetate butyrate 60 Ethyl acetate 280 Isopropyl alcohol 300 Tetrahydrofuran 100 Phosphoric acid (85% concentration) 1.0 Dissolve the above mixture uniformly A surface treatment agent was obtained. The obtained surface treatment agent was coated on the agricultural polyvinyl chloride film produced in Example 1 to obtain a surface-treated agricultural polyvinyl chloride film. The test results for the surface-treated agricultural polyvinyl chloride films obtained in Examples 1 to 3 are shown in Table 2. The test was carried out as a practical house covering material, and its contamination properties were determined.

[Table] The first invention is based on 100 parts by weight of a resin component consisting of 50 to 95 parts by weight of an acrylic copolymer mainly composed of methyl methacrylate and 5 to 50 parts by weight of cellulose acetate butyrate, and 0.1 to 1.0 parts of an inorganic or organic acid. Since a surface treatment agent consisting of parts by weight and a solvent is applied to the surface of the polyvinyl chloride film body, a surface treatment layer with strong adhesion is obtained, and the whole is resistant to cracks and scratches due to bending, stretching, and friction. It provides a high-quality surface, and there is little dust adhesion to the surface-treated surface, and there is little decrease in light transmittance over time.In addition, there is no need to add plasticizers, stabilizers, and other additives to the surface-treated surface. This invention is an agricultural polyvinyl chloride film that has the effect of preventing migration of agents and preventing deterioration of the polyvinyl chloride film. The second invention is the first, and the solvent composition is 5 to 20 parts by weight of methyl ethyl ketone, tetrahydrofuran, or cyclohexanone, which are affinity solvents for polyvinyl chloride, alone or as a mixture, and 80 to 80 parts by weight of a non-solvent for polyvinyl chloride.
The first invention was further improved by using a surface treatment agent comprising 95 parts by weight, and in addition to the practical benefits of improved adhesion, it also improved its coatability, benefiting the uniformity and processability of the film. This is a great invention. As shown above, the agricultural vegetable film obtained by the present invention has good adhesion of the processing agent to the film, prevents the migration of plasticizers etc. to the surface, prevents staining on the film surface, and has a long lifespan. It has been shown to withstand use over a period of time.

Claims (1)

[Scope of Claims] 1. 0.1 to 1.0 parts by weight of an inorganic or organic acid per 100 parts by weight of a resin component consisting of 50 to 95 parts by weight of an acrylic copolymer mainly composed of methyl methacrylate and 5 to 50 parts by weight of cellulose acetate butyrate. An agricultural polyvinyl chloride film obtained by coating the surface of the polyvinyl chloride film with a surface treatment agent consisting of a solvent and a solvent. 2. The solvent composition as set forth in claim 1 is 5 to 20 parts by weight of methyl ethyl ketone, tetrahydrofuran, or cyclohexanone, which are affinity solvents for polyvinyl chloride, alone or as a mixture, and a non-solvent for polyvinyl chloride.
A polyvinyl chloride film for agricultural use using a surface treatment agent comprising 80 to 95 parts by weight.