JP2002322422A - Antifogging coating agent and film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antifogging agent that can exhibit excellent antifogging properties immediately after it is applied, can keep the antifogging properties for a long period and holds high storage stability, and to provide an antifogging film using the same. SOLUTION: The antifogging coating agent comprises 100 pts.wt. of water, 0.1-20 pts.wt. (on the solid basis) of colloidal silica with an average particle size of 2-20 nm, 0.1-10 pts.wt. (on the solid basis) of colloidal alumina, 0.1-10 pts.wt. of a water-soluble resin wherein the weight ratio of the water-soluble resin/(the colloidal silica and the colloidal alumina) is in the range of 0.1-3.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating antifogging agent having excellent storage stability and a film coated with the coating antifogging agent.

[0002]

2. Description of the Related Art Conventionally, when a film used for agricultural purposes such as a pipe house or a tunnel is stretched over a house or the like, water droplets and clouding are generated on the inner surface of the film due to a difference in temperature and humidity between the inside and outside, and the penetration of sunlight is poor. There has been a problem that the growth of the crop is hindered, and water drops grow and fall on the crop, thereby causing a disease. For this reason,
Various proposals have been made to provide an anti-fog layer to agricultural films.
JP-A-7-53747, JP-A-7-82398, JP-A-8-319476, JP-A-11-2
No. 40112 and the like disclose a coating antifogging agent using a combination of colloidal silica and colloidal alumina for the purpose of maintaining the antifogging effect for a long period of time. However, the antifogging layer formed with these coated antifogging agents was not sufficient in properties such as initial antifogging property and antifogging durability.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above,
An object of the present invention is to provide a coated anti-fogging agent and a film which exhibit excellent anti-fogging properties immediately after coating while maintaining high storage stability, and have such properties that they last for a long period of time.

[0004]

The coating antifogging agent of the present invention comprises:
0.1 to 20 parts by weight of a colloidal silica (solid content) having an average particle diameter of 2 to 20 nm and 0.1 to 10 parts by weight of a water-soluble resin with respect to 100 parts by weight of water. The weight ratio is from 0.1 to 3.0.

[0005] The colloidal silica used in the present invention refers to a colloidal dispersion of silica particles in a dispersion medium, and its average particle size is limited to 2 to 20 nm. If the average particle diameter is smaller than 2 nm, aggregation of the particles is likely to occur, so that gelation proceeds and storage stability deteriorates. If the average particle diameter is larger than 20 nm, the adhesion of the particles to the film surface decreases. Therefore, the durability of the applied antifogging agent film is deteriorated. The aspect ratio (major axis / minor axis ratio) is preferably from 1 to 10, and preferably 90% or more of the colloidal silica used is in this range. If the aspect ratio is too large, the adhesion of the colloidal silica when applied to a film becomes insufficient, and the durability may be reduced.

[0006] Other components may be added to the colloidal silica used in the present invention. As the other components, those which shift the isoelectric point of the colloid to a low pH side are preferable. Specifically, lithium oxide, sodium oxide, potassium oxide, magnesium oxide, alkali oxides such as calcium oxide and the like, Oxides are preferred. The addition amount is preferably 0.01 to 3% by weight based on the colloidal silica (solid content). If the addition amount is too large, the storage stability of the applied anti-fog agent may deteriorate.

The water-soluble resin used in the present invention includes:
It is not particularly limited as long as it does not adversely affect the dripping properties and the stickiness of the surface in the applied anti-fog agent film, and is, for example, selected from known water-soluble resins and oligomers, and specifically, methylcellulose and polyethylene oxide. And the like. Particularly, polyethylene oxide is preferable from the viewpoint of applicability to a film or the like and transparency. The weight average molecular weight is preferably 100,000 to 4,000,000, and 1
If it is smaller than 100,000, it may be difficult to apply, and 400
If it is larger than 10,000, the viscosity may be increased and coating may be difficult.

In the present invention, water used in the present invention is used as a dispersion medium of a coating anti-fogging agent, and water alone or a water-soluble organic solvent such as alcohol may be added.

In order to improve the durability and water resistance of the coating antifogging agent film, it is preferable that colloidal alumina is used in the mixing ratio described below in the coating antifogging agent of the present invention.
Known colloidal alumina is used,
The shape of the particles is not particularly limited. The particle diameter is preferably 200 nm or less from the viewpoint of the transparency of the applied anti-fogging agent film.

The mixing ratio of each component in the coating antifogging agent of the present invention is such that 0.1 to 20 parts by weight of colloidal silica as a solid content and 100 parts by weight of water and 100 parts by weight of water are used.
It is limited to 1 to 10 parts by weight. Colloidal silica is 0.
If the amount is less than 1 part by weight, the antifogging property is reduced, and if it exceeds 20 parts by weight, the storage stability is reduced. If the amount of the water-soluble resin is less than 0.1 part by weight, the coatability is poor and the storage stability is lowered.
If the amount exceeds 10 parts by weight, the viscosity of the coating anti-fog agent increases and the coatability deteriorates, and stickiness occurs.

The weight ratio of the water-soluble resin to the colloidal silica (solid content) is limited to 0.1 to 3.0. 0.1
If it is smaller, the storage stability is poor, and if it exceeds 3.0, the applied antifogging agent film becomes sticky and the antifogging property is reduced.

When the colloidal alumina is used as the coating anti-fog agent of the present invention, the proportion of each component is 0.1 to 20 as a solid content of colloidal silica per 100 parts by weight of water.
Parts by weight, 0.1 to 10 parts by weight of colloidal alumina, and 0.1 to 10 parts by weight of water-soluble resin. When the amount of the colloidal silica is less than 0.1 part by weight, the antifogging property is reduced,
If it exceeds 0 parts by weight, the storage stability will decrease. When the colloidal alumina has a low antifogging property, and exceeds 10 parts by weight, the storage stability is low. If the amount of the water-soluble resin is less than 0.1 part by weight, the coatability is poor and the storage stability is lowered. Also, 10
If the amount is more than 10 parts by weight, the viscosity of the coating antifogging agent increases, the coating properties deteriorate, and stickiness occurs.

The weight ratio of the water-soluble resin / (colloidal silica (solid content) + colloidal alumina (solid content)) is limited to 0.1 to 3.0. If it is less than 0.01, the storage stability is poor, and if it exceeds 0.5, the applied antifogging agent film becomes sticky and the antifogging property is reduced.

The pH of the coating anti-fogging agent of the present invention is not particularly limited, but is preferably in the range of 3.0 to 11.0, and more preferably in the range of 4.0 to 10.0. If the pH is too high or too low, the colloidal silica is in a region where ionization and dissolution may occur, and the antifogging performance may not be easily exhibited. Further, the pH is in the range of 7.0 to 11.0 in order to prevent the deterioration and rusting of the production equipment, and to prevent the aggregation of the colloidal silica and alumina to enhance the stability of the applied anti-fogging agent solution. Is preferred. When the pH is lower than 7.0, the aggregation of colloidal silica and alumina may occur, and the stability of the coating anti-fogging agent solution may decrease. When the pH exceeds 11.0, the silica particles dissolve in water and the coating anti-fogging is performed. The agent film may not be formed.

The coating anti-fogging agent of the present invention may contain known coating additives such as viscosity modifiers, emulsions and antifoaming agents, if necessary, as long as the performance of the coating anti-fogging agent is not hindered. May be.

The method for preparing the coating antifogging agent of the present invention includes
Although it is not particularly limited as long as it is a conventionally known method, for example,
A stirring method, a method using a medium shearing internal stirrer such as a homogenizer and a colloid mill may be used.

The coating antifogging agent of the present invention is suitably applied to a resin film, sheet, glass plate or the like at about 80 ° C. for about 1 to about 1 hour.
After a drying process for 10 minutes, an applied anti-fogging agent film is formed,
Used for various applications.

On the surface of a film made of a thermoplastic resin,
A film coated with the coating anti-fog agent is also one of the present invention.

The kind of the thermoplastic resin used in the present invention is not particularly limited.
Polypropylene, vinyl acetate ethylene copolymer, polyvinyl chloride, polyester, polymethyl methacrylate,
Polycarbonate and the like. These may be used alone or in the form of a laminated film or sheet. Among them, a three-layer film composed of a vinyl acetate ethylene copolymer is preferable from the viewpoint of weather resistance, compoundability of additives, and persistence of the anti-fogging agent. An organic-inorganic heat insulating agent, a weathering agent, and the like may be added to the thermoplastic resin constituting the film.

Examples of the above-mentioned inorganic heat insulating agent include silicon oxide, silicates, phosphates, glass fine powder and the like, and are suitably added for improving the heat insulating property of the film and improving the fluctuation of extrusion during molding. The amount added is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the thermoplastic resin. When the amount is less than 0.5 part by weight, a sufficient effect may not be obtained. When the amount exceeds 10 parts by weight, the low-temperature initial anti-fogging property due to the application of the inorganic anti-fogging agent and the adsorption of the anti-fog agent, The mechanical strength of the film may be reduced.

The thermoplastic resin used in the present invention contains a hindered amine-based light stabilizer, a bleed-out inhibitor, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antifoggant to such an extent that the effects of the present invention are not impaired. , A lubricant, a pigment and the like may be added.

The bleed-out inhibitor is not particularly limited, but a metal salt of a straight-chain alkyl sulfonic acid is suitably used. The anti-fog agent is added to suppress whitening of the film surface due to bleed-out. You. The amount of addition was 0.0 to 100 parts by weight of the thermoplastic resin.
Preferred is less than 8 parts by weight, preferably less than 0.06 parts by weight. When the amount is 0.08 parts by weight or more, the antifogging performance of the applied antifogging agent may be reduced.

The ultraviolet absorber is not particularly limited, but, for example, a benzophenone-based, benzotriazole-based, hydroquinone-based, salicylic acid-based, benzoale-based, cyanoacrylate-based ultraviolet absorber and the like are preferably used. The antifog is not particularly limited, and examples thereof include a silicone-based surfactant and a fluorine-based surfactant. Examples of the above lubricant include, but are not particularly limited to, polyethylene wax, fatty acid amide, stearic acid and the like. The heat stabilizer and antioxidant are not particularly limited, and examples thereof include carboxylic acid metal salts, phenolic antioxidants, and chelators such as organic phosphites.

As a method for forming a thermoplastic resin film used in the present invention, a conventionally known film forming method may be mentioned.
For example, an inflation molding method using an extruder, T
It can be manufactured by an extrusion molding method such as a die molding method, a calendar molding method, a solution casting method, or the like.

The method of applying the coating anti-fog agent to the thermoplastic resin film is not particularly limited, and examples thereof include a roll coating method using a gravure coater, a bar coating method, and the like.
A dip coating method, a spraying method, a brushing method and the like can be mentioned. Before applying the coating anti-fog agent, the surface of the thermoplastic resin film may be subjected to various surface treatments. Examples of the method include corona discharge treatment, plasma treatment, ozone treatment, flame treatment, chemical treatment, and primer treatment. As a drying method after the application of the coating anti-fog agent, any of natural drying and forced drying may be adopted. In the case of drying by heating, for example, a hot air drying method, an infrared drying method, a far infrared drying method and the like can be mentioned.

If the film thickness of the film of the present invention is too small, the mechanical strength of the film may be insufficient. If the film thickness is too large, the film forming process and subsequent cutting of the film,
Since handling such as joining and stretching may be inconvenient, the range of 0.02 to 0.30 mm is preferable, and the range of 0.03 to 0.15 mm is particularly preferable.

Since the film of the present invention is coated with the above-mentioned anti-fogging agent, the initial anti-fogging property, anti-fogging durability, transparency,
When the coating film is excellent in uniformity and the pH of the coating anti-fogging agent is adjusted, it has an excellent effect that rust is less generated in production equipment.

[0028]

The colloidal silica compounded in the coating anti-fogging agent of the present invention has an average particle size of 2 to 20 nm.
The storage stability of the coating anti-fog agent becomes excellent. In addition, since it bonds with colloidal alumina or the like at the time of coating, a durable coating antifogging agent film can be formed.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Note that “parts” in the text indicates “parts by weight”.

(Example 1) Preparation of antifogging agent for coating 100 parts of ion-exchanged water, 20 parts of 20 wt% colloidal silica (average particle diameter: 10 nm), 20 parts (4 parts in terms of solid content), and polyethylene oxide (water-soluble resin) Average molecular weight 1
(5-450,000) 1 part of a coating antifogging agent (colloid liquid) having a pH of 5.6 was prepared. The average particle size of the colloidal silica was measured using a light scattering meter (model ELS800) manufactured by Otsuka Electronics Co., Ltd.

Preparation of Film Linear low-density polyethylene (MI = 2.1, density: 0. 1).
94 g / cm3) and low density polyethylene (MI = 2.
1, a resin A in which a density: 0.92 g / cm 3) was mixed at a weight ratio of 2: 1, and an EVA resin (vinyl acetate unit content = 1)
5%, MI = 1.4, density: 0.93 g / cm3) 10
Resin B consisting of 0 parts and 2 parts of an inorganic heat insulating agent, and an EVA resin (vinyl acetate unit content = 5%, MI = 1.3, density:
0.93 g / cm3) Inflation of resin C consisting of 100 parts and 3 parts of an inorganic heat insulating agent into a three-layer structure having a film thickness of 100 μm (thickness ratio A resin / B resin / C resin = 1/7/2). By extruding, a polyolefin resin film was obtained. The obtained anti-fog agent is applied to the obtained polyolefin-based resin film, and a drying oven having a length of 20 m (80 ° C., winding speed 10 m / mi) is applied.
It dried in n) and obtained the film.

(Examples 2 to 4) Coating anti-fogging agents were prepared with the formulations shown in Table 1, and films were obtained in the same manner as in Example 1.

(Example 5) Preparation of coating antifogging agent and preparation of film 100 parts of ion-exchanged water, 20 parts by weight of 20 wt% colloidal silica (average particle diameter: 10 nm), 20 parts (4 parts in terms of solid content), 1
15 parts of 0 wt% colloidal alumina (solid content conversion: 1.
5 parts) and 1 part of polyethylene oxide (average molecular weight: 150,000 to 450,000) as a water-soluble resin, and adjust the pH to 8.5 with sodium hydroxide (1N) to adjust the coating anti-fog agent (colloid liquid). ) Was prepared, and a film was obtained in the same manner as in Example 1.

Examples 6 to 11 Coating anti-fogging agents were prepared in the composition shown in Table 1, and films were obtained in the same manner as in Example 1.

(Comparative Examples 1 to 6) Preparation of coated anti-fogging agent A coated anti-fogging agent was prepared with the composition shown in Table 1, and a film was obtained in the same manner as in Example 1.

<Evaluation of storage stability> Obtained anti-fog agent 4
Take 0 g in a sample bottle, stir well, leave it for one day,
The state of separation of the solution was confirmed, and the results are shown in Table 1. Evaluation criteria: ◎: Not separated at all, 、: Slightly separated,
×: Completely separated.

<Measurement of Haze> With the use of a Haze meter manufactured by Tokyo Denshoku Co., the change with time in the transparency of the film immediately after and one month after the obtained film was measured. The results are shown in Table 1.

<Accelerated antifogging property> The obtained film was placed on the upper part of a water tank filled with water so that the coated surface faces the inside of the water tank, and the external temperature was kept at 15 ° C and the water temperature was kept at 23 ° C, so that the accelerated antifogging property was maintained. The properties were evaluated, and the results are shown in Table 1. The accelerated anti-fogging property was evaluated by drying the film whose surface was wet once, evaluating the anti-fogging property again, and repeating this 5 to 10 times. Evaluation criteria: ◎ It quickly becomes a water film. ：: Growing into a water film after attaching minute water droplets. ×: minute water droplets have been formed for a long time.

[0039]

[Table 1]

[0040]

The coating antifogging agent obtained by the present invention has high storage stability, and the film coated with the coating antifogging agent of the present invention exhibits excellent antifogging properties immediately after coating. In addition, it shows excellent performance that the fogging is small and the anti-fogging property is maintained for a long time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 7/04 CER C08J 7/04 CERS CEZ CEZ C09D 5/00 C09D 5/00 Z 7/12 7/12 C09K 3/00 C09K 3/00 R // C08L 101: 00 C08L 101: 00 F term (reference) 4D075 CA39 DA04 DB31 DB36 DB38 DB40 DB48 DC50 4F006 AA12 AA13 AB33 AB74 AB76 BA10 CA06 DA04 4F100 AA20B AK01A AK01B AK04 AK68 BA02 EH46 GB04 JB09B JB16A JL00 JL07B YY00B 4J038 BA101 DF021 EA011 HA116 HA156 HA216 HA446 KA02 KA06 KA08 KA20 MA08 MA10 NA04 NA06 NA26 PC08

Claims (4)

[Claims] An average particle size of 2 to 2 parts per 100 parts by weight of water.
It consists of 0.1 to 20 parts by weight of 0 nm colloidal silica (solid content) and 0.1 to 10 parts by weight of a water-soluble resin, and the weight ratio of the water-soluble resin / colloidal silica is 0.1 to 3.0. An antifogging agent for coating, characterized in that: 2. An average particle size of 2 to 2 with respect to 100 parts by weight of water.
0.1 to 20 parts by weight of colloidal silica (solid content) of 0 nm, 0.1 to 10 parts by weight of colloidal alumina (solid content), and 0.1 to 10 parts by weight of a water-soluble resin. The weight ratio of (colloidal silica and colloidal alumina) is 0.1 to 3.0. 3. The coating antifogging agent according to claim 1, wherein the pH is in the range of 7.0 to 11.0. 4. A film comprising the film made of a thermoplastic resin and the antifogging agent according to claim 1 applied to the surface thereof.