JP3449526B2 - Anti-fog synthetic resin film - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to polyvinyl chloride,
The present invention relates to a synthetic resin film for agriculture, in particular, which can impart extremely excellent antifogging property to a film surface by applying a synthetic resin such as polyolefin or ethylene-vinyl acetate copolymer to form a coating film.

[0002]

2. Description of the Related Art Synthetic resin films are liable to have static electricity during molding or molding due to the hydrophobic property of the resin, and the surface of the synthetic resin film may become cloudy due to the adhesion of moisture in the air. It causes various obstacles. For example, in an agricultural film, water vapor adheres to the film due to water vapor evaporating from the soil or crops, causing fog to impair transparency. This lowers the transmittance of sunlight and hinders the growth of crops, resulting in a loss of crop yield. In order to improve these drawbacks, it is general to knead a surfactant into the resin to make it hydrophilic, or to make the film surface hydrophilic by surface coating.

Additives used in the former method include sorbitan ester type surfactants, polyglycerin ester type surfactants, polyethylene glycol type surfactants and the like.

Additives used in the latter method include so-called organic antifogging agents such as cationic surfactants such as dimethylalkylammonium chloride and nonionic surfactants such as polyoxyethylene alkylphenol ether and polyoxyethylene sorbitan fatty acid ester. And so-called inorganic anti-fogging agents such as an agent, a combination system of colloidal silica and a water-soluble aluminum salt, a combination system of colloidal silica and alumina sol, and synthetic hectoride (JP-A-8-53558).

However, the agricultural film produced by using the former method has a certain degree of anti-fog persistence, but has a defect that lacks rapid effect in the initial stage of spreading and its sustainability in the long term is still insufficient. It had drawbacks. Further, in the case of an agricultural film produced by the latter method, a film coated with an organic antifogging agent has a shortcoming in that it has a short-term sustainability but a film surface is sticky, although it has a rapid effect. Further, regarding the aqueous solution of the inorganic anti-fogging agent, the coatability to the film is poor, and although the coated film is not sticky, the adhesive strength to the film surface of the coating film is weak and it easily peels off due to physical irritation. There are drawbacks.

[0006]

As a result of intensive studies in view of such conventional circumstances, the present inventors have found that a specific surfactant is added to an aqueous solution containing synthetic hectorite as an antifogging agent. By doing so, the coating property is dramatically improved without lowering the continuous antifogging property, and by blending an acrylic or polyolefin emulsion,
The inventors have found that a film having an excellent antifogging effect (persistence) in long-term use and having excellent adhesive strength of a coating film can be obtained without lowering the initial antifogging effect (quick attack), and completed the present invention. .

The synthetic hectorite in the present invention is a synthetic substance which belongs to a natural clay mineral in classification and has a crystal three-layer structure and is similar to a hectorite belonging to an unlimited layer expansion type trioctahedral which has an expansion lattice. Its representative structural formula is [Si ₈ (Mg _5.34 Li _0.66 ) O ₂₀ (OH.F) ₄ ] M.
_+0.66 or [Si ₈ (Mg _5.34 Li _0.66 ) O ₂₀ (OH) ₄ ] M +
It is displayed as _0.66 (M + is almost all Na ⁺ ). Specifically, it is exemplified by the trade name “LAPONITE” manufactured by Nippon Silica Industry Co., Ltd.

This synthetic hectorite is dispersed as a transparent colloidal sol in an aqueous solution, and when it is applied to a film and dried, it gels on the resin surface to form a uniform coating film.

The synthetic hectorite concentration in the antifogging agent aqueous solution composition is 0.05 to 10% by weight. When the concentration is lower than 0.05% by weight, sufficient antifogging property cannot be obtained, and when the concentration is higher than 10% by weight, the viscosity is drastically increased, which makes workability in coating the antifogging agent difficult.

The synthetic resin in the present invention is vinyl chloride,
Includes copolymerization of basic vinyl with other monomers, vinylidene, ethylene, vinyl acetate, vinyl ethers, maleates, etc., including blends of polyvinyl chloride with other polymers. Further, ethylene, polypropylene, ethylene-vinyl acetate copolymer, polybutadiene, polymethylpentene, polybutene, polypentene, and polyolefin resins including such copolymers, polyester resins such as polybutylene terephthalate and polyethylene terephthalate, polystyrene, Acrylonitrile-butadiene-styrene copolymer, acrylonitrile-
Styrene resins such as styrene copolymers, other acrylic resins, polycarbonates, and blends of various polymers are also included. These resins require plasticizers, stabilizers, lubricants, UV absorbers, antioxidants,
It may also contain pigments, slip agents and the like.

[0011]

EXAMPLES Next, the present invention will be described in detail by showing examples.

The evaluation resins are polyvinyl chloride (PVC, compounding contents are as follows), low density polyethylene (LDPE, MI
= 2), ethylene-vinyl acetate copolymer (EVA / VA
There are three types, with a content of 15% and MI = 2). The test and evaluation conditions and methods are as follows.

[Coating Method] A synthetic resin film having a thickness of 0.1 mm was soaked in a test solution mixed with each formulation, and the film was evenly coated by the exposure.
Then, it was dried with hot air at 70 ° C.

[Low temperature anti-fog property] 20 in a 200cc beaker
Put 100 cc of water at ℃, put a film, fix it with a rubber band, put it in a thermostat at 0 ℃, and check the degree of water drop ◎,
Evaluation was made by the four-point method of ○, △, ×. ◎ indicates that the surface is uniformly wet and no water droplets are observed. × indicates that small water droplets are attached to the front surface. ○ and △ are intermediate states. About this low temperature anti-fog property, one day after the start of evaluation, the initial anti-fog property was evaluated,
Three months after the start of the evaluation, the antifogging property was evaluated.

[High temperature anti-fog property] 50 ml of a mayonnaise bottle of 500 cc filled with water and fixed with a rubber band is used.
Leave it in a constant temperature layer at ℃ for 4 hours,
Evaluation by the point method. Regarding this high-temperature anti-fog property, one day after the start of evaluation was evaluated as initial anti-fog property and 3 months after the start of evaluation was evaluated as continuous anti-fog property.

[Adhesive strength] In accordance with JIS K5400 general coating test method 6.15 substrate test, a cut is made with a cutter knife, and cellophane adhesive tape (18 mm wide JIS / Z1522 equivalent) is applied to the scratched surface for a fixed amount. A load was applied by hand and peeled at a constant speed, and changes in the coating film at this time were observed. The results were evaluated by 4 points: ⊚ (no change in coating film), ◯ (slightly peeled), Δ (peeled), × (all peeled).

[Transparency] The transparency of each sample after 3 months used in the above antifogging test was visually observed. The result is ○
(Transparency is good), Δ (slightly inhibited), and × (inhibited) were evaluated. The formulations and evaluation results of Examples and Comparative Examples are shown below.

[0018]

[Table 1]

For PVC, the following compounding compositions were mixed by a conventional means, and then a film having a thickness of 0.1 mm was coated with an aqueous solution of an antifogging agent at a predetermined concentration shown in Table 1 to form a test film. did. Each performance (anti-fogging property, adhesive strength, transparency: test method is as described above) of these test films was evaluated, and the results are shown in Table 2.

As for LDPE and EVA, a film having a thickness of 0.1 mm was prepared by extrusion using the above materials. An aqueous solution of antifogging agent was applied to this film at a predetermined concentration shown in Table 1 to prepare a test film. Each performance (anti-fogging property, adhesive strength, transparency: test method is as described above) of these test films was evaluated, and the results are shown in Table 3.
And shown in Table 4.

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

As shown in the examples, the product of the present invention has improved coating properties as compared with conventional coating antifogging agents, is excellent in initial and continuous low-temperature / high-temperature antifogging properties, and has strong adhesive strength. A film is obtained, the transparency of the film is improved, and the utility value is extremely high.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08J ^7/ 04-7/06 B32B 27/00-27/42

Claims (2)

(57) [Claims] 1. A synthetic hectorite clay minerals, that coating the antifogging agent solution composition comprising an acrylic or polyolefin emulsion and glycerol mono-caprate as the component on the surface of the synthetic resin film to form a coating film Anti-fog synthetic resin film characterized by. 2. A glycerol mono-caprate monoesters content of 90% or more, antifogging synthetic resin film according to claim 1, wherein the fatty acid forming the ester is not less than 70% capric acid.