JPH0415811B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a sheet for agricultural use that is particularly weather resistant and is obtained using a specific vinyl chloride resin. In recent years, in vinyl chloride-based resin molded products in various fields, so-called elongation molded products that have lost the plastic luster have become popular, and various elongation techniques have been developed. Erasing technology that uses resin is attracting particular attention. In other words, the erasing technology that uses partially cross-linked vinyl chloride resin has the following advantages: (1) it does not drastically reduce mechanical properties unlike the erasing technology that uses a large amount of filler; and (2) it does not require acrylic coating. This is because it has advantages such as (3) it does not involve an increase in cost unlike the erasing technique, and (3) it does not require special equipment like the erasing technique using embossing. Therefore, compositions containing various partially crosslinked vinyl chloride resins have recently been studied. For example, a proposal to obtain a partially crosslinked vinyl chloride resin using a crosslinking agent such as diallyl phthalate, diallyl maleate, polyethylene glycol diacrylate, or polyethylene dimethacrylate, and to utilize a composition using it Publication No. 54-80354,
JP-A-56-5843, JP-A-54-152054, JP-A-56-92024, etc.). However, the use of these partially crosslinked vinyl chloride resins has the disadvantage that the weather resistance of the molded products deteriorates significantly, so if we try to apply them to the production of agricultural sheets that are normally used outdoors, large amounts of polyvinyl chloride resins are required. However, it is necessary to use UV absorbers, heat stabilizers, anti-aging agents, etc., resulting in high costs. In view of the above-mentioned circumstances, the present inventors have conducted intensive research to apply partially crosslinked vinyl chloride resin to the production of agricultural sheets. The same applies hereinafter) and a vinyl chloride resin having a gel content of 30% or less, wherein the gel content is vinyl chloride or a monomer mixture (A) containing vinyl chloride as a main component and bisphenol-modified diacrylate or bisphenol-modified dimethacrylate. We have discovered that a sheet for agricultural use containing a partially crosslinked vinyl chloride resin obtained by copolymerizing a monomer mixture (B) consisting of I have completed my invention. In the present invention, the gel fraction (gel fraction) is a value calculated by extracting with tetrahydrofuran for 22 hours using a Soxhlet extractor and calculating the dry weight of the extraction residue remaining on a 350 mesh filter. . In addition, the agricultural sheets used in this specification refer to sheets used in vinyl greenhouses, sheets used in outdoor cultivation, etc., which are used for purposes such as preventing dew condensation, preventing marbling, and retaining heat. . In the present invention, a monomer mixture (A) consisting of vinyl chloride or a monomer mixture mainly composed of vinyl chloride and a bisphenol-modified diacrylate or a bisphenol-modified dimethacrylate (B) is used.
The gel fraction obtained by copolymerizing exceeds 1.0%,
A partially crosslinked vinyl chloride resin having a content of 35% or less or a mixed resin containing a partially crosslinked vinyl chloride resin and a vinyl chloride resin such that the gel fraction exceeds 1.0% and is 35% or less is used. The bisphenol-modified diacrylate or bisphenol-modified dimethacrylate as the crosslinking agent used in the present invention has the general formula (): General formula (): or general formula (): (In the formula, R ₁ is H atom or -CH ₃ group, R ₂ is H
Atom or alkyl group having 1 to 4 carbon atoms, R ₃ , R ₄
is an H atom, -CH ₃ group, -CH ₂ CH ₃ group, -
Atoms or groups selected from CH ₂ CH ₂ COOH groups,
i and j are integers from 1 to 5, m and n are integers from 1 to 10,
1 is 0 or an integer of 1 to 20, and X is a Cl atom, a Br atom, or a hydrogen atom) is preferably used. The amount to be copolymerized with vinyl chloride or monomer mixture (A) is
The above crosslinking agent is preferably used in an amount of 0.35 to 8 parts per 100 parts (parts by weight, hereinafter the same) of (A). The production of the partially crosslinked vinyl chloride resin used in the present invention is disclosed in JP-A-57-195711 and other publications. In the present invention, a partially crosslinked vinyl chloride resin can be used alone, but usually as a dissipating agent, polyvinyl chloride resin, vinyl chloride-ethylene copolymer resin, vinyl chloride-propylene copolymer resin, vinyl chloride- Vinyl acetate copolymer resin, copolymer resin of vinyl chloride and acrylic acid or its derivatives, etc. have a gel fraction of more than 1.0% in the total resin component,
The product is blended to a concentration of 35% or less, and heat stabilizers, lubricants, antioxidants, rubbers, ultraviolet absorbers, processing aids, pigments, plasticizers, etc. are blended as necessary and molded. Semi-rigid or soft agricultural sheets can be obtained. If the gel fraction in the total resin component exceeds 35%, the weather resistance will be insufficient, while if it is less than 1.0%, the wear-out effect will not be significant, and both are unfavorable. As the heat stabilizer added when producing the agricultural sheet of the present invention, known heat stabilizers used for vinyl chloride resins can be used, such as tin stabilizers such as octyltin maleate. Lead-based stabilizers such as tribasic lead sulfate, metal soaps, Ca-Zn-based stabilizers, Ba-based stabilizers, etc. may be used alone or in combination. Further, as the lubricant, known lubricants such as polyethylene wax-based lubricants, stearic acid-based lubricants, and alcohol-based lubricants may be used alone or in combination. Further, thermoplastic resins that can be used in combination include acrylic rubber and EVA. The plasticizers used for further softening include known plasticizers such as phthalic acid plasticizers such as dioctyl phthalate, polyester plasticizers, phosphate ester plasticizers, and epoxy plasticizers, alone or Can be used in combination. Further, as the molding method used for manufacturing the agricultural sheet of the present invention, common methods such as calendar molding and extrusion molding can be used. Moreover, the molding conditions can be the same as those for ordinary vinyl chloride resins. Hereinafter, the agricultural sheet of the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples. Reference Examples 1 to 3 (Manufacture of partially crosslinked vinyl chloride resins (1) to (3)) In a stainless steel polymerization vessel with an internal volume of 300, 200 parts of ion-exchanged water, 0.2 parts of partially saponified polyvinyl acetate, and 0.06 parts of diisopropyl peroxide. 1 part, 0.06 part of lauroyl peroxide, and 0.5 part of bisphenol-modified diacrylate shown in Table 1 were charged, and after degassing, 100 parts of vinyl chloride monomer was charged, and polymerization was carried out at a polymerization temperature of 68° C. for 15 hours. The resulting slurry was dehydrated and dried in a hot air dryer at 55°C for 24 hours to obtain a white powder. Table 1 shows the gel fraction of the powder obtained. Reference Examples 4 to 8 (Production of partially crosslinked vinyl chloride resins (4) to (8)) Ion-exchanged water and partially saponified polyvinyl acetate were prepared in the same manner as in the production of partially crosslinked vinyl chloride resins (1) to (3). ,
1.0 parts of diisopropyl peroxide, lauroyl peroxide, and the crosslinking agent shown in Table 1 were charged, and after degassing, vinyl chloride monomer was charged, and polymerization was carried out at a polymerization temperature of 68°C for 15 hours, followed by the same operations as in Reference Examples 1 to 3. A white powder was obtained. Table 1 shows the gel fraction of the obtained powder. Reference Examples 9 to 10 (Production of partially crosslinked vinyl chloride resins (9) to (10)) Reference Examples 1 to 3 except that the crosslinking agent used in the production of partially crosslinked vinyl chloride resin (2) was 8 parts. Partially crosslinked vinyl chloride resin (9) was obtained in exactly the same manner as above, and partially crosslinked vinyl chloride resin (10) was obtained in exactly the same manner as in Reference Examples 1 to 3 except that the amount of crosslinking agent was changed to 0.3 parts. Gel fraction is 38% and 0.8 respectively
It was %. Examples 1 to 8 Partially crosslinked vinyl chloride resins (1) to (3) and (9) were used and blended in a super mixer at 130°C for 5 minutes based on the formulation shown in Table 2. The compound was kneaded for 15 minutes using a mixing roll controlled at 165°C, and the resulting sheet was gradually fed into an inverted L-shaped calender to form a 0.3mm sheet.
I got a thick calendar sheet. Various properties of the obtained calendar sheet were measured and evaluated by the methods shown below. The results are shown in Table 2, and it can be seen that the sheet of the present invention has excellent wearability and significantly improved weather resistance. Erasing property: Visually observe the surface condition of a 0.3 mm thick sheet obtained by calendar molding as shown in the above example: ◎: Very good, ○: Good, △: Slightly elongated and ×: Evaluation was made on a four-level scale. Weather resistance: The same sheet as above was deteriorated for 200 hours using a sunshine weather meter, and then the elongation rate was measured. In addition, the measurement of elongation rate is
This was done in accordance with JIS K6724. The deterioration conditions were that the test sample was exposed to rain for 18 minutes every 2 hours at 63°C, and the front and back sides of the test sample were changed every 20 hours. Comparative Examples 1 to 8 Using the partially crosslinked vinyl chloride resins (4) to (10), calender sheets with a thickness of 0.3 mm were obtained in the same manner as in Examples 1 to 8 based on the formulation shown in Table 2. Various properties of the obtained calender sheets were measured and evaluated in the same manner as in Examples 1 to 8. The results are shown in Table 2, and the sheets obtained in Comparative Examples 1 to 8 have poor weather resistance when they have good weather resistance, and conversely, when they have good weather resistance, they have insufficient weather resistance. I understand that. In addition, Kanevinyl S-1001 and Kaneace PA-20 in Table 2 are each trade names manufactured by Kanebuchi Chemical Industry Co., Ltd., and the gel fraction in the total resin component is the gel of partially crosslinked vinyl chloride resin. This is a value calculated based on the fraction.

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Claims (1)

[Scope of Claims] 1. A vinyl chloride resin having a gel content of more than 1.0% by weight and 35% by weight or less in all resin components, wherein the gel content is vinyl chloride or vinyl chloride as the main component. A resin containing a partially crosslinked vinyl chloride resin obtained by copolymerizing a monomer mixture (A) consisting of a monomer mixture (A) and a monomer mixture (B) consisting of a bisphenol-modified diacrylate or a bisphenol-modified dimethacrylate, which has excellent weather resistance. Agricultural sheet for consumption. 2 Bisphenol-modified diacrylate or bisphenol-modified dimethacrylate has the general formula (): (In the formula, R ₁ is H atom or -CH ₃ group, R ₂ is H
Atom or alkyl group having 1 to 4 carbon atoms, R ₃ , R ₄
is H atom _{, -CH3} group, _{-CH2CH3 group} , _-CH2CH2
Atoms or groups selected from the COOH group, m, n
is an integer from 1 to 10, X is a Br atom, a Cl atom, or a H
The agricultural sheet according to claim 1, which is a compound represented by (atom). 3 Bisphenol-modified diacrylate or bisphenol-modified dimethacrylate has the general formula (): (In the formula, R ₁ , R ₃ , R ₄ , and X are the same as above, and l is 0 or an integer of 1 to 20.) sheet. 4 Bisphenol-modified diacrylate or bisphenol-modified dimethacrylate has the general formula (): (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , l, and X are the same as above, and i and j are integers of 1 to 5.) Sheet for agricultural use. 5 Vinyl chloride resin whose gel content in the total resin component is more than 1.0% by weight and not more than 35% by weight,
The agricultural sheet according to claim 1, which is the partially crosslinked vinyl chloride resin. 6 Vinyl chloride resin whose gel content in the total resin component is more than 1.0% by weight and not more than 35% by weight,
The agricultural sheet according to claim 1, which is a mixed resin of the partially crosslinked vinyl chloride resin and the vinyl chloride resin.