JPS6340670B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an agricultural spreading material having a dripping property, and more specifically, it is made by coating the surface of a transparent glass plate or synthetic resin sheet with an improved dripping prevention agent. Concerning agricultural spreading materials that are free from dew and frost.

With the recent development of greenhouse horticulture, agricultural spreading materials include films such as polyvinyl chloride film, polyethylene film, and polyethylene terephthalate film, as well as hard plates and glass, which are used for various purposes.

It is well known that these spreadable materials are mainly used during periods when the outside temperature is low, and that the difference in temperature between the inside and outside causes dew condensation on the inner surface of the spreadable material, which significantly impedes the transmission of light rays.

Various methods have been used in the past to prevent this reduction in light transmission due to dew condensation.

Polyvinyl chloride film, polyethylene film, etc. are kneaded with a surfactant as a droplet-imparting substance during molding to give them droplet properties, but they have the disadvantage of poor durability and a large amount of droplets. It is difficult to apply this method to polyethylene terephthalate films, which become difficult to mold if they are kneaded with properties.

In addition to kneading a droplet agent, there is also a method of coating the surface of a synthetic resin sheet with a hydrophilic resin such as polyvinyl alcohol, but this method also has the disadvantage of poor durability due to water rinsing. A coating agent droplet improvement method in which colloidal silica is added to a sulfonic acid group-containing polyester as a hydrophilic substance also has problems in practicality because the droplet effect decreases when used for a long time.

In addition, after spreading the spreading material on greenhouses, etc., a substance that has a droplet property is applied by spraying, etc., which has been effective, but in this case, it increases the work burden on farmers, and it also increases the burden on farmers. In some cases, spray cannot be applied, so on-site droplet treatment has problems such as complicated work and restrictions on the scope of application.

Therefore, the present inventor conducted extensive research on agricultural spreading materials with durable droplet properties, and discovered a droplet composition that can be used as a coating agent that can be applied to the surface of glass or synthetic resin sheets. reached.

That is, the present invention provides transparent inorganic glass,
On at least one surface of a plate or sheet made of organic glass (synthetic resin sheet), (a) colloidal silica or colloidal alumina, (b) sulfonic acid group-containing polyester resin, and (c) melamine-based or epoxy-based crosslinkable compound. This is an agricultural spreading material consisting of a laminate obtained by applying and drying an aqueous dispersion of a composition consisting of:

In the present invention, the outer layer made of the compositions (a) to (c) exhibits a dew condensation prevention effect and a droplet effect.

The agricultural spreading material of the present invention is an inorganic glass represented by a glass plate that can be used for conventionally known facility garden turf, or an organic glass commonly represented by a synthetic resin film or sheet, such as polyvinyl chloride. Soft or hard materials such as polyethylene, polypropylene, polycarbonate, and polyethylene terephthalate can be used. In particular, it contains UV absorbers consisting of polyethylene terephthalate or has a low density (density less than 1.39 g/cm ³ , preferably
1.38 g/cm ³ or less) is preferred because of its excellent weather resistance. Polyvinyl chloride containing an ultraviolet absorber is also preferred as a base material for agricultural spreading materials.

For colloidal silica and colloidal alumina, commercially available aqueous dispersions with an average particle size of 10 to 200 nm (nanometers) can be used.

The ratio of the resin component to colloidal silica or colloidal alumina is preferably 10 to 120 to 100 of the resin component; if it is less than this, the droplet flow will be insufficient, and if it is too much, the water resistance of the coating will deteriorate, so it should be avoided. be.

Further, by adding colloidal silica or colloidal alumina, it is possible to exhibit the effect of preventing clouding when the resin component is crosslinked and comes into contact with water. In this case, the blending ratio is based on 100% of the resin component.
70-120 is particularly preferred.

The sulfonic acid group-containing polyester resin may be one that can be dissolved or dispersed in water, and those having a wide range of molecular weights can be used. For example, a commercially available aqueous (aqueous solution or dispersion) polyester resin can be used. As an example of this, "Pesresin" manufactured by Takamatsu Yushi Co., Ltd.
4000".

The crosslinking compound is a crosslinking agent that forms an aqueous solution or an aqueous dispersion, and is preferably a melamine-based or epoxy-based one. For example, Sumitex M manufactured by Sumitomo Chemical Co., Ltd.
-3'' is a suitable crosslinking compound.

The blending ratio of the sulfonic acid group-containing polyester and the crosslinking compound is suitably in the range of 20:1 to 3:1; if the polyester resin is too large, the crosslinking reaction will not be sufficient and durability will be insufficient. Furthermore, if the amount of polyester resin blended is small, the adhesion to the base sheet will be poor, and the droplet effect will also be low.

Note that a catalyst can also be used to promote the crosslinking reaction.

Further, some commercially available sulfonic acid group-containing polyesters tend to cause blocking after coating, but in order to prevent this, it is appropriate to add 5% or less of particles. For example, inorganic particles such as silica powder and organic particles such as polyethylene particles having an average particle size of 0.5 to 5 μm can be used. The amount of particles added should be kept below 5% so that cloudiness after application of the coating is not noticeable.

This will be explained below using examples.

Example 1 “Pess Resin 4000” (Takamatsu Yushi Co., Ltd.) is a commercially available aqueous dispersion as a sulfonic acid-containing polyester resin.
1% by weight of "Syroid 244" (fine particle silica, manufactured by Fuji Davison Co., Ltd.), which is an inorganic particle, was added to the solution (manufactured by Fuji Davison Co., Ltd.) and dispersed in a ball mill for 2 hours. 7% water-soluble "Epoxy Denacol EX-611" (manufactured by Nagase Sangyo Co., Ltd.) was added to 90 parts by weight of a 7% polyester resin dispersion.
% aqueous solution was added thereto, and 85 parts by weight of a 7% aqueous dispersion of "Snowtex 20L" (manufactured by Nissan Chemical) as colloidal silica was further added and thoroughly stirred.

To this composition, 6 parts by weight of a 7% aqueous solution of caustic potash was added as a catalyst, and a 0.4 μm thick film was applied to the surface of a 175 μm thick polyethylene terephthalate biaxially stretched film.
It was coated with a percoater to a thickness of .
After drying and solidifying the droplet agent, we tested it using a droplet tester and found that it could withstand 720 repetitions. As a comparison, it was found that the droplet-treated film without the addition of colloidal silica had water droplets attached to the surface after 100 repetitions, and the durability of the droplet effect was low.

In addition, the droplet test machine sets the film at a 45° angle and exposes it to a zero atmosphere with the upper side kept at 5°C and the lower side kept at 30°C, and the humidity at 30°C is increased to 40% every hour.
Droplet durability is displayed as the number of repetitions until water droplets adhere to the entire surface while changing to 90%.

Example 2 A 10% aqueous solution of "Pessresin 4000" as a sulfonic acid-containing polyester aqueous dispersion and "Sumitex M-3" (manufactured by Sumitomo Chemical) as a melamine compound10
To 100 parts of a 9/1 ratio mixture of 9/1% liquid, 100 parts of "Snowtex 20L" and 3 parts of a 10% ammonium chloride aqueous solution as a catalyst were added, and coated with a percoater to a polyester film 175 μm (Sixlite: manufactured by Teijin) with a thickness of 0.5 μm. I applied it to make it thick.
When this was subjected to the same droplet test machine as in Example 1, the droplet flowability remained good even after 720 repetitions.

Comparative Example A coating material prepared in the same manner as in Example 2 except that the melamine compound was omitted was applied under the same conditions, and the coating film immediately fell off in a droplet tester.

Furthermore, when colloidal silica was removed in Example 2, water droplets adhered to the entire surface after 48 repetitions.

Claims (1)

[Scope of Claims] 1. A composition comprising colloidal silica or colloidal alumina, a sulfonic acid group-containing polyester resin, and a crosslinkable compound is coated on at least one surface of a plate or sheet made of organic glass or inorganic glass that transmits visible light. Agricultural spreading material that is coated. 2. The agricultural spreading material according to claim 1, wherein the crosslinkable compound is a melamine compound or an epoxy compound. 3. The agricultural spreading material according to claim 1, wherein the plate or sheet made of organic glass is a synthetic resin selected from polyvinyl chloride, polyethylene terephthalate, and polyethylene.