JPH0223573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to an improved method for producing agricultural vinyl chloride resin films or sheets containing tannins.

"Prior Art" Conventionally, when synthetic resin films or sheets containing tannins (hereinafter abbreviated as T agent) are used as agricultural heat insulators, they protect agricultural crops and fruits,
It is known to be useful for increasing production, accelerating ripening, improving taste, and preventing pests and diseases (see Patent No. 49504 and Patent No. 468324).

Conventionally, methods for using T agent in synthetic resin films or sheets include adding T agent alone or an alcoholic solution of T agent to synthetic resin powder, or adding an alcoholic solution of T agent and a phosphoric acid ester to synthetic resin powder. A method is known in which a liquid mixture is uniformly mixed and then formed into a film or sheet using a conventional method. However, when the T agent is mixed with the resin powder using these methods, it is difficult to mechanically and uniformly mix a small amount of the T agent into a large amount of the resin powder using the T agent alone, resulting in insufficient dispersion of the T agent. Therefore, the obtained film or sheet had the disadvantage that the transparency was poor and the surface was rough. In addition, when an alcoholic solution of agent T or a mixture of an alcoholic solution of agent T and a phosphoric acid ester is mixed with synthetic resin powder (Japanese Patent Publication No. 59-50174), agent T is uniformly dispersed, but the alcohol used During the mixing and film-forming processes, most of the material is emitted into the atmosphere, which is a waste of resources and is also undesirable from a sanitary and safety standpoint.

On the other hand, there is a method of using water instead of alcohol and mixing it as an aqueous solution of the T agent, but the film or sheet may foam during the film forming process, especially when the synthetic resin is polyvinyl chloride resin. This is undesirable because the compounding auxiliaries used may be adversely affected, such as being hydrolyzed.

"Problems to be Solved by the Invention" The present inventors have solved the above-mentioned problems, that is, by uniformly dispersing the T agent in a vinyl chloride resin composition without using alcohol, it is possible to achieve transparency. As a result of intensive research aimed at producing agricultural vinyl chloride resin films or sheets with excellent The present invention was completed based on the discovery that the present invention can be mixed very well and uniformly into a resin composition in which auxiliary agents such as plasticizers and stabilizers are mixed and blended.

"Means for Solving the Problems" Therefore, the gist of the present invention is to produce a film using a resin composition in which a phosphoric acid ester solution obtained by heating and dissolving tannins in a phosphoric acid ester is blended with a vinyl chloride resin. The present invention provides a method for producing an agricultural soft vinyl chloride resin film or sheet, which is formed into a shape or a sheet.

To explain the present invention in more detail, the raw material vinyl chloride resin (hereinafter abbreviated as PVC) used in the method of the present invention includes polyvinyl chloride, vinyl chloride and other monomers such as vinyl acetate, ethylene, propylene, etc. , copolymers with alkyl vinyl ethers, acrylic esters, methacrylic esters, acrylonitrile, etc., and polyvinyl chloride or the above-mentioned polyvinyl chloride copolymers containing chlorine such as chlorinated polyethylene, chlorinated polypropylene, and chlorinated polyisoprene. Polymer blends with polymers or copolymers may be mentioned.

The present invention is not affected in any way by the type and degree of polymerization of the above resin.

In the method of the present invention, a commercially available T agent to be blended into an agricultural film or sheet (hereinafter simply referred to as film) may be used as it is, but it may be purified if necessary. The amount of T agent to be used is preferably 0.01 to 1 part by weight per 100 parts by weight of PVC to achieve the purpose of the present invention.

Examples of phosphoric esters that dissolve the T agent include tricresyl phosphate (hereinafter referred to as TCP).
), tricylenyl phosphate,
Preferred examples include tributyl phosphate, triethyl phosphate, 2-ethylhexyl diphenyl phosphate, cresyl diphenyl phosphate, dixylenyl cresyl phosphate, dicresyl xylenyl phosphate, etc. These can be used alone or in combination of two or more.

The amount of phosphoric acid ester used can be changed as appropriate depending on the amount of T agent used, and taking into consideration the dispersibility and solubility of T agent, it should be at least 10 times the weight of T agent used, especially 10 to 20 It is preferable to use twice as much. The temperature condition for dissolving is preferably 120 to 180°C, particularly preferably 140 to 160°C. Although it depends on the amount of phosphoric acid ester used, if it is less than 120°C, dissolution will be insufficient, and if it exceeds 180°C, oxidative deterioration of the T agent will become severe, which is not preferable.

In addition to the phosphoric acid ester, the resin composition used in the method of the present invention can contain plasticizers that are usually added to PVC, such as di-2-ethylhexyl phthalate (DOP), diisodecyl phthalate, butylbenzyl phthalate. phthalate ester plasticizers such as dioctyl adipate, aliphatic dibasic acid ester plasticizers such as dioctyl sebacate, glycol ester plasticizers such as diethylene glycol dibenzoate, fatty acid ester plasticizers such as butyl oleate. Examples of other plasticizers include trioctyl trimellitate, chlorinated paraffin, and alkylbenzene. These plasticizers may be used alone or in combination.

The blending amount of the plasticizer is preferably about 20 to 70 parts by weight based on 100 parts by weight of the raw material PVC. Plasticizer amount is 20
If it is less than 70 parts by weight, it will be difficult to obtain a film with sufficient flexibility to be used when stretched as an agricultural film, and if it is more than 70 parts by weight, the film will not only become too soft and its mechanical strength will decrease, but also become sticky. This is not desirable because it will look like this.

In addition to the above-mentioned plasticizer, the resin composition used in the method of the present invention further includes an antifogging agent, an antifog agent (an additive that suppresses fog generation), a lubricant, a heat stabilizer, an antioxidant, an antistatic agent, and a stabilizer. Of course, various commonly used additives such as chemical additives, antifungal agents, antialgal agents, and coloring agents may be appropriately blended.

To obtain a flexible PVC film for agricultural use according to the method of the present invention, the T agent is added to phosphoric acid ester in an amount of at least 10 times (parts by weight) to the T agent, and after dissolving by heating and stirring at 140 to 160°C, PVC with plasticizers, stabilizers,
This solution is added to a mixture containing a colorant and other various additives as necessary, and after stirring and mixing using a conventional mixing means such as a ribbon blender or a blender such as a Banbury mixer, the solution is mixed using a calender roll or a mixer. can be easily formed into a film using an ordinary molding machine such as an extrusion molding machine.

"Action" and "Effects of the Invention" Compared to films or sheets obtained by conventional methods, the film obtained by the method of the present invention has better dispersibility and transparency of the T agent without using too much alcohol. Therefore, it is preferable from the viewpoint of resource saving and safety and health, and its industrial value as an agricultural covering material is great.

"Examples" The method of the present invention will be explained in detail based on the following examples, but the present invention will include the following:
It is not limited to the following examples.

Examples and Reference Examples A total of five types of films, Film A as an Example and Films B, C, D, and E as Reference Examples, were prepared by adding and blending the T agent to a formulation having the following composition by the method described below. The transparency and film appearance were compared.

Compound PVC (=1450) 100 parts by weight DOP 45 Epoxy compound 3 Barium-zinc composite liquid stabilizer 2 Barium-zinc composite powder stabilizer 1 Anti-fog agent (sorbitan monostearate)
2 Film A: 0.1 part by weight of T agent to 3 parts by weight of TCP
In addition, the mixture was heated to 150°C and stirred to make a homogeneous solution, which was gradually added to the premixed above-mentioned mixture while stirring, dry-applied, and then formed into a film using a calender to form a film of 0.1 m/m. A thick film was created.

Film B: 0.1 part by weight of T agent was dissolved in 0.1 part by weight of methyl alcohol (same weight as the T agent), this was further added to 3 parts by weight of TCP, and the mixture was premixed by stirring to make a homogeneous solution. The mixture was gradually added to the above-mentioned mixture with stirring, dried up, and then formed into a film using a calender to form a film with a thickness of 0.1 m/m.

Film C: Add 3 parts by weight of TCP to the above formulation and pre-mix the mixture, and add an alcohol solution in which 0.1 part by weight of T agent is dissolved in 2 parts by weight of methyl alcohol (20 times the amount of T agent) while stirring. After drying, a film of 0.1 m/m thickness was produced using a calender.

Film D: A film was produced under exactly the same conditions as in the production of Film C, except that the amount of methyl alcohol used was reduced from 2 parts by weight to 0.1 parts by weight (same weight as the T agent), and Film D was obtained. .

Film E: A film was prepared under the same conditions as in the case of making Film C, except that no methyl alcohol was used and the T agent was used as it was, and Film E was obtained.

FIG. 1 shows the results of measuring the light transmission characteristics according to wavelength for the above five films A to E.

In the figure, the horizontal axis represents wavelength, and the vertical axis represents light transmittance. From FIG. 1, it can be seen that film A (film obtained by the method of the present invention) is similar to film B obtained by dissolving the T agent in alcohol and then adding it to a phosphoric ester, as well as other films C, D, and E. Compared to other films, the absorption in the ultraviolet region is deep (absorbs well), and in the visible region, the transmittance is high, indicating that visible light is transmitted well. It shows that it is evenly distributed. Also, in terms of appearance, film A is as good as film B, while films D and E have rough film surfaces, indicating poor dispersion of the T agent.

Moreover, the method of the present invention can obtain excellent dispersibility and transparency without using alcohol, and can maintain extremely high environmental hygiene compared to conventional methods that use alcohol, making it safe. The top is also preferred.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a light transmission curve for each wavelength of the film. In the figure, the horizontal axis represents wavelength, and the vertical axis represents light transmittance. Film A: Film of Example; Films B, C, D, E: Films of Reference Example.

Claims (1)

[Claims] 1. A soft chloride for agricultural use, characterized in that it is made by molding into a film or sheet a resin composition in which a phosphoric ester solution obtained by heating and dissolving tannins in a phosphoric ester is blended with a vinyl chloride resin. A method for producing vinyl resin films or sheets.