JP6178062B2 - Anti-fogging coating - Google Patents

Description

The present invention relates to an antifogging resin composition and an antifogging coating that can exhibit high antifogging properties and can form a film having high strength and excellent weather resistance and heat resistance.

Houses and tunnels for crop cultivation use agricultural films such as polyethylene and polyvinyl chloride, various types of glass, mirrors, etc., but with these members, water vapor condenses and adheres to the surface. As a result, there has been a problem of preventing the transmission of light. In addition, the windshield, rear glass, and the like of automobiles also have problems such as a reduction in visibility due to cloudiness.
As an anti-fogging technique for automobile window glass and the like, a method of increasing the glass surface temperature is most commonly used. That is, if it is a windshield, warm air is blown on the glass surface, and if it is a rear glass, the glass is heated by a heater embedded in the glass. On the other hand, in summer when the temperature and humidity are high, a method of cooling the interior of the vehicle to lower the humidity in the air and lowering the dew point is used.
However, it is difficult to constantly control the temperature and humidity in the vehicle interior by opening and closing doors for opening and exiting, opening and closing windows, and taking in outside air. In particular, if a vehicle that has been left when the outside air temperature is low or the humidity is high and the vehicle is started without sufficiently warming up, a large amount of cloudiness is likely to occur at the start of operation.

On the other hand, Patent Document 1 discloses an antifogging coated synthetic resin window material in which a silicone hard coat layer is formed on an exothermic pattern layer. In such a technology, the surface temperature of the optical article is increased, and the moisture in the air is prevented from condensing on the surface to provide antifogging properties. However, the heater part and the energy source are indispensable. There was a problem that became too complicated.

In recent years, therefore, attempts have been made to form various antifogging films on the surface of the window glass of a vehicle. Examples of the antifogging film include hydrophilic antifogging films. By forming a hydrophilic anti-fogging film, moisture generated near the glass surface first spreads quickly on the hydrophilic coating and prevents water droplets. As such a hydrophilic type anti-fogging film, an organic hydrophilic film such as a surfactant, polyvinyl alcohol, or polyethylene glycol is used. However, these are water-soluble or not wear-resistant. And it could not be a permanent measure.

On the other hand, a water absorption type antifogging agent has also been developed. As a water absorption type antifogging agent, for example, Patent Document 2 discloses the use of a silica fine particle porous film and a water absorbent resin.
However, these water-absorbing membranes do not have sufficient water-absorbing ability, and further improvement is necessary for the development of anti-fogging properties due to water absorption. In addition, since the generation of cloudiness is suppressed by storing moisture in the film, it is inferior in terms of water resistance, and there is a problem that the film expands or dissolves due to long-term use. . In addition, there is a problem that the anti-fogging performance is lowered.

In addition, the anti-fogging agent of the water absorption type has low film strength, and when applied to the surface of the window glass of the vehicle by changing the shape when applied, the haze is generated and the visibility of the window glass is improved There was also the problem of a drop. In addition, there is a problem that the weather resistance of the film is lowered.

Japanese Patent No. 3844255 JP 2000-239045 A

The present invention provides an antifogging resin composition and an antifogging coating that can exhibit high antifogging properties and can form a film having high strength, weather resistance, and heat resistance. The purpose is to do.

In the present invention , an antifogging resin composition is coated on a substrate having a glass plate and a plurality of protrusions made of glass or resin formed on the glass plate, and the antifogging resin composition things, a water-soluble polyvinyl acetal resin and water, the water-soluble polyvinyl acetal resin has an average polymerization degree of 700 to 4,500, the amount of hydroxyl groups is 45 to 85 mol% and the degree of acetalization is 2 to 40 mol% And the ratio of the structural unit acetalized with the aromatic aldehyde is 90-95% among all the structural units acetalized, and content of the said water-soluble polyvinyl acetal resin is 3-20 weight% This is an anti-fogging coating .
The present invention is described in detail below.

The present inventor uses a water-soluble polyvinyl acetal resin having a predetermined structure as a constituent resin of the antifogging resin composition, and sets the average degree of polymerization, the amount of hydroxyl groups, and the degree of acetalization within a predetermined range. The inventors have found that an antifogging resin composition capable of forming a film having high strength, excellent weather resistance and heat resistance while maintaining antifogging properties is obtained, and the present invention has been completed.

The antifogging resin composition of the present invention has an average degree of polymerization of 700 to 4500, a hydroxyl group amount of 45 to 85 mol%, an acetalization degree of 2 to 40 mol%, and all the acetalized structural units. Among them, a water-soluble polyvinyl acetal resin containing 90% or more of a structural unit acetalized with an aromatic aldehyde is contained.

The water-soluble polyvinyl acetal resin of the present invention has a lower average polymerization degree of 700 and an upper limit of 4500. When the average degree of polymerization is less than 700, the viscosity of the antifogging resin composition containing the water-soluble polyvinyl acetal resin decreases, dripping occurs during coating, or the surface smoothness of the coating film decreases. To do.
When the average degree of polymerization exceeds 4,500, the leveling property at the time of coating decreases, and the unevenness on the surface of the coating film increases. The preferable lower limit of the average degree of polymerization of the water-soluble polyvinyl acetal resin of the present invention is 800, and the preferable upper limit is 4000. A more preferred lower limit is 2800, and a more preferred upper limit is 3600. If the average degree of polymerization is less than 2800, the strength and haze of the molded product may be reduced, and if it exceeds 3600, the antifogging property may be reduced.
In addition, in this specification, the average degree of polymerization of water-soluble polyvinyl acetal resin can be calculated | required from the average degree of polymerization of modified polyvinyl alcohol which is a raw material. Moreover, in this specification, the average degree of polymerization of modified polyvinyl alcohol means the average value calculated | required from the polymerization degree of each modified polyvinyl alcohol in the modified polyvinyl alcohol which is a mixture.

In the water-soluble polyvinyl acetal resin, the lower limit of the amount of hydroxyl groups is 45 mol%, and the upper limit is 85 mol%. When the amount of the hydroxyl group is less than 45 mol%, the water absorption of the water-soluble polyvinyl acetal resin is lowered, or the viscosity stability of the antifogging resin composition is lowered. If the amount of the hydroxyl group exceeds 85 mol%, the water-absorbing property of the water-soluble polyvinyl acetal resin is increased and the stability is lowered. The preferable lower limit of the hydroxyl group amount is 50 mol%, and the preferable upper limit is 80 mol%, the more preferable lower limit is 70 mol%, and the more preferable upper limit is 79 mol%. If the amount of the hydroxyl group is less than 70 mol%, it may be difficult to achieve both the antifogging property and the strength of the molded product. If the amount of hydroxyl group exceeds 79 mol%, the strength of the molded product may be reduced.

In the water-soluble polyvinyl acetal resin, the lower limit of the degree of acetalization is 2 mol%, and the upper limit is 40 mol%. When the degree of acetalization is less than 2 mol%, the water absorption is good, but the water resistance is poor and sufficient antifogging properties cannot be obtained. If it exceeds 40 mol%, the adhesion of the antifogging resin composition to a substrate such as glass is lowered.
The preferable lower limit of the degree of acetalization is 5 mol%, and the preferable upper limit is 15 mol%. A more preferred lower limit is 6 mol%, and a more preferred upper limit is 10 mol%.

In the water-soluble polyvinyl acetal resin, the proportion of structural units acetalized with an aromatic aldehyde is 90% or more of all acetalized structural units (total degree of acetalization). Thereby, even when the degree of acetalization is low, an antifogging resin composition having good water absorption, water resistance and transparency can be obtained.
When the proportion of the structural unit acetalized by the aromatic aldehyde is less than 90%, the water resistance is deteriorated and sufficient antifogging properties cannot be obtained.
A preferred lower limit of the proportion of structural units acetalized with the aromatic aldehyde is 93%, a more preferred lower limit is 98%, and a preferred upper limit is 100%. If the proportion of the structural unit acetalized by the aromatic aldehyde is less than 98%, the strength of the molded body may be lowered.

Examples of the aromatic aldehyde include benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, other alkyl-substituted benzaldehydes, chlorbenzaldehyde, and other halogen-substituted benzaldehydes.
An aromatic aldehyde having a substituent such as a hydroxy group, an alkoxy group, an amino group, or a cyano group on the aromatic ring may be used. Of these, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, and 4-methylbenzaldehyde are preferable.

The water-soluble polyvinyl acetal resin can be obtained by acetalizing polyvinyl alcohol in water with an aldehyde containing an aromatic aldehyde.

Aldehydes other than the aromatic aldehyde described above are not particularly limited, and examples include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, glyoxal, glutaraldehyde, and the like. Is mentioned. Among them, it is preferable to use acetaldehyde or butyraldehyde alone or use acetaldehyde and butyraldehyde in combination.

The minimum with preferable content of the said water-soluble polyvinyl acetal resin in the anti-fogging resin composition of this invention is 3 weight%, and a preferable upper limit is 20 weight%. By setting it within the above range, there is no unevenness during coating, and an anti-fogging function can be exhibited.

The antifogging resin composition of the present invention contains water in addition to the water-soluble polyvinyl acetal resin.
Although it does not specifically limit as said water, Pure water etc. can be used.

In the antifogging resin composition of the present invention, various known additives may be blended within a range not impeding the effects of the present invention. As the above additives, glycerin, ethylene glycol, polyethylene glycol, various other surfactants, antioxidants, anti-aging agents, ultraviolet absorbers, silane coupling agents, titanium coupling agents for improving water absorption performance, Examples include leveling agents, thixotropic agents, anti-skinning agents, plasticizers, thickeners, diluents, reactive diluents, crosslinking agents, fillers, pigments (pigments, dyes), preservatives, fungicides, and the like.

As the surfactant, any one of anionic, cationic and nonionic may be used. Examples of the antioxidant include phenol-based, aromatic amine-based, sulfur-based, phosphorus-based and the like. Examples of the antiaging agent include amines and phenols.

The antifogging resin composition of the present invention uses a water-soluble polyvinyl acetal resin having a predetermined structure as a constituent resin, and by setting the average degree of polymerization, the amount of hydroxyl groups, and the degree of acetalization within a predetermined range, While maintaining anti-fogging properties, excellent coating properties, water resistance and adhesiveness can be realized.
The use of the antifogging resin composition of the present invention is not particularly limited. For example, various glass such as rear glass, side glass, windshield, sunroof, and rearview mirror for automobiles, agricultural coating films such as polyethylene and polyvinyl chloride, pets, etc. Examples thereof include an antifogging agent used for bottles and labels thereof. Moreover, the antifogging resin composition of this invention can be used also for the antifogging coating | covering material of various glass.

When using the antifogging resin composition of this invention as an antifogging coating material of glass, it does not specifically limit as glass used, The transparent glass generally used can be used. Specific examples include inorganic glass such as float glass, polished glass, template glass, netted glass, lined glass, colored glass, heat ray absorbing glass, heat ray reflecting glass, and green glass.
When the antifogging coating layer is formed by coating the antifogging resin composition of the present invention, the thickness of the antifogging coating layer to be formed is not particularly limited, but effectively exhibits the antifogging performance. Therefore, 3-100 micrometers is preferable and 5-50 micrometers is more preferable.

Further, by applying the antifogging resin composition of the present invention on a substrate having a glass plate and a plurality of projections made of glass or resin formed on the glass plate, the antifogging coating object is provided. Can be produced.
Such an antifogging coating is also one aspect of the present invention.
By adopting such a configuration, the strength of the formed protrusion can be improved.
The shape of the protrusion is not particularly limited, and examples thereof include a cylinder, a cone, and a pyramid. The antifogging resin composition of the present invention may be applied in the form of a film on a glass plate and protrusions, or may be applied so that a flat surface is formed on the glass plate and protrusions.

According to the present invention, an antifogging resin composition and an antifogging coated article that can exhibit high antifogging properties and can form a film having high strength, weather resistance, and heat resistance. Can be provided.

Examples 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.

( Reference Example 1)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 1700, saponification degree 88 mol%), 170 g of 35 wt% hydrochloric acid and 39 g of benzaldehyde were added, and the acetalization reaction was carried out for 5 hours while maintaining the liquid temperature at 10 ° C. And a sponge-like reaction precipitate slurry was obtained. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution having a concentration of 9%.
The water-soluble polyvinyl acetal resin in the obtained solution has a hydroxyl group amount of 80 mol%, an acetalization degree (total acetalization degree) of 7 mol%, and a ratio of structural units acetalized with an aromatic aldehyde of 100 mol%. %Met.

(Example 2)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 2200, saponification degree 88 mol%), a total of 42 g of aldehyde consisting of 170 g of 35 wt. The acetalization reaction was carried out for 5 hours while being retained to obtain a sponge-like reaction precipitate slurry. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution having a concentration of 9%.
The water-soluble polyvinyl acetal resin in the obtained solution has a hydroxyl group content of 78 mol%, an acetalization degree (total acetalization degree) of 8 mol%, and a proportion of structural units acetalized by an aromatic aldehyde of 93 mol%. %Met.

(Example 3)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 3300, saponification degree 88 mol%), 45 g of aldehyde consisting of 170 g of 35 wt% hydrochloric acid, 43 g of 2-methylbenzaldehyde and 2 g of butyraldehyde was added, and the liquid temperature was adjusted. While maintaining at 10 ° C., acetalization reaction was performed for 5 hours to obtain a sponge-like reaction precipitate slurry. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution having a concentration of 8%.
The water-soluble polyvinyl acetal resin in the resulting solution had a hydroxyl group content of 77 mol%, an acetalization degree (total acetalization degree) of 9 mol%, and a ratio of structural units acetalized with an aromatic aldehyde of 95 mol%. %Met.

Example 4
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 4000, saponification degree 88 mol%), 45 g of aldehyde consisting of 170 g of 35 wt% hydrochloric acid, 43 g of 2-methylbenzaldehyde and 2 g of butyraldehyde was added, and the liquid temperature was adjusted. While maintaining at 10 ° C., acetalization reaction was performed for 5 hours to obtain a sponge-like reaction precipitate slurry. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution having a concentration of 8%.
The water-soluble polyvinyl acetal resin in the resulting solution had a hydroxyl group content of 77 mol%, an acetalization degree (total acetalization degree) of 9 mol%, and a ratio of structural units acetalized with an aromatic aldehyde of 95 mol%. %Met.

(Comparative Example 1)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 600, saponification degree 88 mol%), 170 g of 35 wt% hydrochloric acid and 35 g of 4-methylbenzaldehyde were added, and the acetal was maintained for 5 hours while maintaining the liquid temperature at 10 ° C. The reaction was carried out to obtain a sponge-like reaction precipitate slurry. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution having a concentration of 9%.
The water-soluble polyvinyl acetal resin in the obtained solution has a hydroxyl group amount of 82 mol%, an acetalization degree (total acetalization degree) of 6 mol%, and a proportion of structural units acetalized with an aromatic aldehyde is 100. %Met.

(Comparative Example 2)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 1200, saponification degree 88 mol%), an aldehyde total 42 g consisting of 170 g of 35% by weight hydrochloric acid, 37 g of 3-methylaldehyde and 5 g of butyraldehyde was added, and the liquid temperature was adjusted. While maintaining at 10 ° C., acetalization reaction was performed for 5 hours to obtain a sponge-like reaction precipitate slurry. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution containing 10% concentration.
The water-soluble polyvinyl acetal resin in the obtained solution has a hydroxyl group amount of 78 mol%, an acetalization degree (total acetalization degree) of 8 mol%, and a proportion of structural units acetalized by an aromatic aldehyde of 88 mol%. %Met.

(Comparative Example 3)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 1700, saponification degree 88 mol%), 170 g of 35% by weight hydrochloric acid, 9.8 g of benzaldehyde and 0.2 g of butyraldehyde were added in an amount of 10 g of aldehyde. Was kept at 10 ° C. for 5 hours to obtain a sponge-like reaction precipitate slurry. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution having a concentration of 10%.
The water-soluble polyvinyl acetal resin in the obtained solution has a hydroxyl group content of 85 mol%, an acetalization degree (total acetalization degree) of 2 mol%, and a proportion of structural units acetalized with an aromatic aldehyde of 88 mol%. %Met.

(Comparative Example 4)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 1700, saponification degree 88 mol%), 170 g of 35 wt% hydrochloric acid and 125 g of benzaldehyde were added, and the acetalization reaction was carried out for 5 hours while maintaining the liquid temperature at 10 ° C. And a sponge-like reaction precipitate slurry was obtained. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain a water-soluble acetal resin solution having a concentration of 9%.
The water-soluble polyvinyl acetal resin in the obtained solution has a hydroxyl group amount of 50 mol%, an acetalization degree (total acetalization degree) of 25 mol%, and a proportion of structural units acetalized with an aromatic aldehyde of 88 mol%. %Met.

(Comparative Example 5)
To 3000 g of an aqueous solution containing 350 g of polyvinyl alcohol (average polymerization degree 1700, saponification degree 88 mol%), 170 g of 35 wt% hydrochloric acid and 200 g of benzaldehyde were added, and the acetalization reaction was carried out for 5 hours while maintaining the liquid temperature at 10 ° C. And a sponge-like reaction precipitate slurry was obtained. The slurry was washed and neutralized with water to remove the hydrochloric acid catalyst and unreacted aldehyde, and then dried to obtain a resin precipitate. This resin was dissolved in a 60/40 mixed solvent of water / isopropyl alcohol (alcohol solvent) to obtain an aqueous acetal resin solution having a concentration of 11%.
The water-soluble polyvinyl acetal resin in the obtained solution has a hydroxyl group amount of 40 mol%, an acetalization degree (total acetalization degree) of 40 mol%, and a proportion of structural units acetalized with an aromatic aldehyde is 100. %Met.

<Evaluation>
The following evaluation was performed about the water-soluble polyvinyl acetal resin aqueous solution obtained by the reference example, the Example, and the comparative example. The results are shown in Table 1.

(1) Anti-fogging (1-1) Resin layer forming glass Water having a water-soluble polyvinyl acetal resin aqueous solution having nano protrusions on the glass surface so that the thickness after drying with a coater is 5 μm (imprint molding) Coating on the surface of the SP glass having a nano pattern formed thereon, a lattice pattern of about 100 × about 100 nm, a groove depth of about 120 nm, and a groove width of about 100 nm), followed by drying for 3 hours to obtain a polyvinyl acetal resin. A resin layer-formed glass having a layer formed thereon was obtained.
The state of the polyvinyl acetal resin layer after the obtained resin layer-formed glass was immersed in 1 L of water for 5 minutes as it was was visually observed and judged according to the following criteria.
Moreover, the resin layer forming glass in which the thickness of the polyvinyl acetal resin layer was 20 μm and the resin layer forming glass in which the thickness of the polyvinyl acetal resin layer was 30 μm were similarly evaluated.

(1-2) Evaluation of anti-fogging property After putting 450 g of water at 30 ° C. into a container (500 cc) having an opening, the resulting resin layer surface is covered with the opening so as to be inside and sealed at room temperature (20 ° C. ) Was set in a room set at), then set at a low temperature (0 ° C.) and left for 5 seconds. And the cloudiness state of the resin layer forming glass was evaluated visually according to the following criteria.
Moreover, it replaced with the resin sheet and the same evaluation was performed also about the case where the obtained 3 types of resin layer forming glass is used.

◎ Cloudiness and water droplets were not seen.
〇 A few large drops of water were seen.
△ Many small water droplets were seen.
× The entire surface was clouded.

(2) Molded body strength
The resin layer-formed glass obtained in “(1) Anti-fogging property” was covered with a cloth (Nel cloth No. 600, made of cotton, double-sided raising), and then a 500 g weight was placed thereon and reciprocated 50 times. Then, the state of the resin sheet was confirmed visually.
◎ The molded body maintained its original state
〇 The molded body remains 95% original
△ The molded body maintains 80% original state
× The molded body remains 60% original

(3) Haze measurement The haze of the resin layer-formed glass after “(2) molded body strength” was measured using a HAZEMETER MODEL HM-150W2.

(4) The surface strength of the resin layer-formed glass obtained in “(1) Antifogging property” was measured based on the pencil hardness test of JIS K 5600-6-4. Note that “◯” indicates no flaw and “×” indicates flaw.

According to the present invention, an antifogging resin composition and an antifogging coated article that can exhibit high antifogging properties and can form a film having high strength, weather resistance, and heat resistance. Can be provided.

Claims (1)

And the glass plate, on a substrate having a plurality of projections made of formed glass or resin on the glass plate, anti-fogging resin composition are applied,
The antifogging resin composition contains a water-soluble polyvinyl acetal resin and water,
The water-soluble polyvinyl acetal resin has an average degree of polymerization of 700 to 4500, a hydroxyl group amount of 45 to 85 mol% and an acetalization degree of 2 to 40 mol%, and among all the acetalized structural units, aromatic The proportion of structural units acetalized with a group aldehyde is 90-95%,
Antifogging coated object content of the water-soluble polyvinyl acetal resin you wherein <br/> 3 to 20 wt%.