JPH0866991A - Condensation preventing laminate film or sheet - Google Patents

Abstract

PURPOSE: To manufacture a transparent laminate film and a transparent laminate sheet of superior condensation preventing effect which can prevent the condensation under the high humidity environment or temperature or on a boundary where the humidity difference is remarkable for a long period of time continuously and generate no creases, to which sticking or removing can be carried out easily. CONSTITUTION: A polyvinyl alcoholic resin layer 3 is laminated on a substrate base layer 1, insoluble in water and provided with total beam transmittance of 90% or over, through a bonding agent layer 2, on the surface of which a water absorption layer 4 of a composition composed of polyvinyl alcoholic resin (A) of saponification of 95 molar % or over and polymerization degree of 500-2500 and an isobutyrene-maleic acid-maleic alkaline metal salt copolymer (B) containing carboxyl of 25-56% in the shape of alkaline metal salt and having the weight ratio of A/B=90/10-20/80.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a mirror surface of a bathroom, a window glass of an automobile, a train, a house, a glass plate in a greenhouse, a lens of eyeglasses, goggles or a curved mirror, etc. under a high humidity environment or under a remarkable temperature. It is useful for sticking to glass surfaces at different boundaries to prevent condensation for a long time.
The present invention relates to a dew condensation preventing laminated film or sheet (hereinafter, simply referred to as a film).

[0002]

2. Description of the Related Art Conventionally, various proposals have been made to prevent condensation of transparent glass and plastic products, and they have been put into practical use. [Raft Yoshito: Ed. Company p81-106 (1989)]. This is roughly classified into: a) a method of kneading a surfactant to improve the wettability of the surface of a molded article: for example, sorbitan fat-resistant ester, glycerin fat-resistant ester, polyoxyethylene sorbitan fat-resistant ester, When surfactants such as polyoxyethylene sorbitol oil and acid ester, polyoxyethylene alkyl ether, and sucrose oil and acid ester are added to the resin and molded into a film, the compatibility with the resin causes Surfactant bleeds. When water droplets adhere to the surface, the surfactant enters the water droplets, lowers the surface tension of the water droplets, spreads the water droplets, and maintains transparency. b) A method of applying a hydrophobic substance to the surface of a molded product to improve the water repellency of the surface: For example, a hydrophobic substance such as silicone oil, liquid paraffin or vaseline is applied to the surface of the molded product such as a film and the surface is To improve the water repellency of and to make water drops flow down. c) A method in which a resin having a high affinity for water is applied to the surface of a molded article and water drops adhering to the surface are absorbed: For example, as a resin having a high affinity for water, starch / polyacrylic acid is used. A water-absorbent resin, polyvinyl alcohol, methyl cellulose, or the like is used, and this is applied to the surface of a film or the like to absorb water droplets attached to the surface. d) A method of preventing the dew condensation by keeping the surface of the molded article at a temperature always higher than the dew point: For example, a heating element is attached to the inner surface of the glass to heat the glass to prevent the dew condensation.

However, in the method a), the surfactant kneaded in the resin exhibits a dew condensation preventing effect by bleeding out on the surface of the film or the like. Therefore, when the surfactant is repeatedly contacted with water, The surfactant dissolves and flows out, and the dew condensation preventing effect is lost. That is, the dew condensation prevention effect by this method is only an initial effect and poor in sustainability;
In the method b), the water-repellent substance applied to the surface of the molded article flows out when repeatedly contacted with water, so that it has poor sustainability and has no effect on fine water droplets. Further, it is difficult to apply it uniformly, and there are drawbacks such that the coating film formed by this application becomes sticky and the transparency of the molded product after application is impaired; Although it is superior to the methods a) and b), it is not yet sufficient, and since it has a high affinity for water, the part in contact with water droplets swells and the surface hardness decreases and wrinkles or peeling occur. . The method of d) requires a large initial investment and a high power cost, and can be used only for special purposes. For these reasons, a method obtained by further improving the method c) is generally used as a method for obtaining a condensation-preventing molded article.
However, since polyvinyl alcohol-based resin is mainly used in this method, it has a high affinity for water, and the portion in contact with water droplets swells to generate wrinkles. In addition, the water absorption of the polyvinyl alcohol-based resin cannot exhibit a long-lasting antifogging effect under high humidity or at a boundary surface where the temperature is significantly different.

[0004]

Therefore, as an anti-condensation film which has been improved, a polyvinyl alcohol resin is further cross-linked with an organic silicon compound (silane compound or silane coupling agent) (JP-A-48-4).
7939, JP-A-3-81586, 3-81587, 3-181588,
3-181589), a composition comprising a modified polyvinyl alcohol having a silyl group in the molecule and an inorganic material (JP-A-59-179684), polyvinyl alcohol and isobutylene-anhydrous on a polyester film. The one coated with a mixed solution with a maleic acid copolymer (JP-A-5-310978) has been proposed. However, and the resulting film can sufficiently prevent the decrease in surface hardness and the occurrence of wrinkles due to swelling, but the film becomes hydrophobic, so that it is effective in preventing dew condensation on the environment of high humidity and at the interface where the temperature is remarkably different. Is poor in sustainability.
Since the film obtained by the above method has a low water absorption amount, it cannot exhibit a dew condensation preventing effect for a long period of time under the same conditions. Therefore, the object of the present invention is to prevent condensation for a long period of time in a high humidity environment or at a boundary surface where the temperature or humidity difference is significantly different, and wrinkles do not occur,
It is intended to provide a transparent laminated film having an excellent effect of preventing dew condensation, which can be easily attached and peeled off.

[0005]

Means for Solving the Problems The inventors of the present invention have been solving the above-mentioned problems by using JP-A-59-64650 and JP-A-60-2104.
As a result of further research based on the description in JP-A-44, a composition obtained by adding an isobutylene-maleic acid-maleic acid alkali metal salt copolymer to a polyvinyl alcohol-based resin is laminated on the polyvinyl alcohol-based resin surface. Laminated film, focusing on the fact that the water absorption is significantly improved compared to a polyvinyl alcohol-based resin film of the same thickness, by applying the above composition to the surface of the polyvinyl alcohol-based resin film as a water-absorbing layer, It has been found that the water absorption of the polyvinyl alcohol resin film can be improved. Further, the adhesive strength between the supporting substrate layer and the polyvinyl alcohol-based resin layer, moisture absorption, water absorption or drainage, due to drainage, a shear strength stronger than the stretching force between the water-absorbing layer and the polyvinyl alcohol-based resin layer is given, If a polyvinyl alcohol-based resin layer is laminated on one surface of the supporting substrate layer made of a hydrophobic resin, and the water absorbing layer is formed on the surface thereof, and an adhesive layer is provided on the other surface of the supporting substrate layer, The present inventors have found that this laminated film can be easily attached to the surface of glass or the like and can have an effect of preventing dew condensation, and have reached the present invention.

That is, the dew condensation-preventing laminated film according to the present invention has a normal thickness of water insoluble and a total light transmittance of 90% or more as illustrated in the longitudinal sectional views of FIGS. 1 and 2.
A polyvinyl alcohol resin layer 3 having a normal thickness of 5 to 500 μm is laminated on a supporting base layer 1 having a thickness of 10 to 800 μm with an adhesive layer 2 interposed therebetween, and a water absorbing layer having a normal thickness of 1 to 15 μm is formed on the surface thereof. The water absorption layer has a saponification degree.
Polyvinyl alcohol resin (A) having a polymerization degree of 500 to 2500 and 95 mol% or more, and 25 to 25% of the carboxyl groups in the copolymer.
Composition comprising 50% by weight of isobutylene-maleic acid-alkali metal maleate maleic acid copolymer (B) in the form of an alkali metal salt, in a weight ratio (A) / (B) = 90/10 to 20/80. In addition, the pressure-sensitive adhesive layer 5 is provided on the other surface of the supporting base layer 1. In the figure, 6 is a release paper.

The present invention will be described in more detail. The supporting substrate layer 1 used in the dew condensation-preventing laminated film of the present invention is not particularly limited as long as it is a highly transparent and water-insoluble film, and transparent such as polyester, polyethylene, polyvinyl chloride and polymethylmethacrylate. Synthetic resin. If the thickness of these films is less than 10 μm, wrinkles are likely to occur due to the expansion and contraction of the moisture absorption / exhaust layer due to moisture absorption / exhaust, and if it exceeds 800 μm, the construction tends to be difficult and the cost will increase. The thickness of is used. If the total light transmittance is less than 90%, the transparency tends to be insufficient, which is not preferable.

As the polyvinyl alcohol-based resin which can be used for the polyvinyl alcohol-based resin layer 3 laminated on the supporting base layer 1 with the adhesive layer 2 interposed therebetween, vinyl acetate such as vinyl acetate or vinyl formate or t-butyl ether, It is obtained by hydrolyzing a polymer obtained by polymerizing vinyl ether such as trimethylsilyl vinyl ether with an acid or an alkali. Generally, a polymer obtained by polymerizing vinyl acetate is hydrolyzed from the viewpoint of cost. is there. The saponification degree of the polyvinyl alcohol-based resin is 95 mol% or more, preferably 98 mol% or more, and the polymerization degree is 500 or more, preferably 1000 to 2500, more preferably 1000 to 2000.
Is. When the saponification degree is less than 95 mol%, the polyvinyl alcohol-based resin layer has poor water resistance, so that the polyvinyl alcohol-based resin layer swells and wrinkles occur, or the polyvinyl alcohol-based resin layer dissolves to form a supporting substrate layer. Peels off. If the degree of polymerization is less than 500, the mechanical strength of the obtained film becomes low, which is not preferable. The degree of polymerization is 2500
When it exceeds, the viscosity of the polyvinyl alcohol-based resin in the molten state is extremely high, making it difficult to form a film.

The method for forming a film of these polyvinyl alcohol-based resins may be any method as long as it can form an independent thin film, but industrially, an inflation molding method or a T-die was used. The melt extrusion molding method is preferable because of its high molding efficiency. The polyvinyl alcohol-based resin film thus obtained may be heat-treated or stretched if necessary. In this film-forming stock solution,
If necessary, to the extent that the transparency and water resistance of the film are not impaired, carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, starch or its derivatives, xanthan gum, polysaccharides such as carrageenan,
Water-soluble resins such as water-soluble synthetic polymers such as polyacrylic acid or its derivatives, polyacrylamide, poly-N-vinylpyrrolidone, polyethylene oxide, plasticizers such as glycerin, polyethylene glycol or ethanolamine, nonionic or anionic Surfactants, pH adjusters, various antifoaming agents, preservatives and the like can also be added. Thickness of polyvinyl alcohol resin layer is 5μ
If it is less than m, the dew condensation prevention effect tends to be insufficient, and 500 μm
If it exceeds the range, the construction becomes difficult and the cost increases, which is not preferable.

The adhesive forming the adhesive layer 2 interposed between the polyvinyl alcohol resin layer 3 and the supporting substrate layer 1 has the ability to prevent the expansion / contraction of the moisture absorption / exhaust layer due to moisture absorption / extraction. Since an adhesive force having a shear strength greater than the force is required, a urethane two-component reactive type (polyethylene glycol or polyester having hydroxyl groups at both ends, a reactive type of polyamine or polycarboxyl group and isocyanate) adhesive, epoxy Resin adhesives are preferred. These adhesives have excellent water resistance and high temperature and humidity resistance. Note that wrinkles are likely to occur if the water-absorbent layer and the polyvinyl alcohol-based resin layer are bonded together with an adhesive having a shear strength equal to or less than the stretching force.

The polyvinyl alcohol resin used for forming the water absorbing layer 4 is obtained by hydrolyzing a polymer obtained by polymerizing a vinyl ester such as vinyl acetate or vinyl formate or a vinyl ether such as t-butyl ether or trimethylsilyl vinyl ether with an acid or an alkali. However, it is generally preferable that the polymer obtained by polymerizing vinyl acetate is hydrolyzed from the viewpoint of cost. The saponification degree of the polyvinyl alcohol resin is 95 mol% or more, preferably 98 mol%, and the polymerization degree is 500 to 2500, preferably 1000 to 2000. When the saponification degree is less than 95 mol%, the transparency of the laminated film is poor, which is not preferable. If the degree of polymerization is less than 500, the strength of the thin film will decrease and cracks will occur on the film surface. When the degree of polymerization exceeds 2500, the viscosity becomes so high that it becomes difficult to form a water absorbing layer.

Isobutylene-maleic acid-used for forming the water absorbing layer 4 together with this polyvinyl alcohol resin
As the maleic acid alkali metal salt copolymer, an isobutylene-maleic anhydride copolymer hydrolyzed with an aqueous solution of an alkali metal compound or an alkaline earth metal salt compound is used. The alkali metal compound or alkaline earth metal compound mentioned here is sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide or the like. Ratio of carboxyl groups in the isobutylene-maleic acid-maleic acid alkali metal salt copolymer forming an alkali metal salt (hereinafter referred to as the degree of neutralization)
Is 25 to 50%, preferably 30 to 50%. It is very difficult to hydrolyze isobutylene-maleic anhydride with an alkali metal compound or an alkaline earth metal compound to prepare an isobutylene-maleic acid-alkali metal maleate copolymer having a degree of neutralization of less than 25%. is there. The degree of neutralization
If it exceeds 50%, the compatibility with the polyvinyl alcohol resin becomes poor, and the film becomes cloudy and a transparent film cannot be obtained.In addition, the polyvinyl alcohol resin and isobutylene-maleic acid-maleic acid alkali metal salt are not obtained. The copolymer undergoes phase separation, resulting in an opaque laminated film.

The weight composition ratio of the polyvinyl alcohol resin (A) and the isobutylene-maleic acid-alkali metal maleate copolymer (B) is the weight ratio of (A) / (B).
90/10 to 20/80, especially 70/30 to 40/60
It is preferably in the range of. If the weight composition ratio of the polyvinyl alcohol resin is more than 90/10, the function as the water absorbing layer cannot be sufficiently exhibited. In addition, this weight composition ratio is 20
If it is less than / 80, the polyvinyl alcohol-based resin and the isobutylene-malenic acid-malenic acid alkali metal salt copolymer composition are separated from the polyvinyl alcohol-based resin layer. If necessary, a surfactant such as acetylene alcohol, acetylene glycol, or glycerin fatty acid ester ester may be added to the water absorbing layer.

The water absorbing layer 4 to be formed has a thickness of 1.0 to 15 μm, preferably 3 to 10 μm. This is 1.0
If it is less than μm, the amount of water absorption is small, and the antifogging effect tends to be poor in an environment with high humidity or a significantly different temperature difference.
If it exceeds 15 μm, the volume of the water absorbing layer after water absorption tends to increase remarkably. Generally, the method of forming the water absorbing layer 4 on the polyvinyl alcohol resin layer 3 is preferably performed by a casting method. Specifically, after dissolving a mixed solution of polyvinyl alcohol-based resin and isobutylene-maleic acid-alkali metal maleate copolymer to a predetermined concentration, a wire bar on the polyvinyl alcohol-based resin layer, a die coater,
It can be obtained by coating with a reverse coater or knife coater and then drying. After drying again,
If necessary, heat treatment may be performed.

The dew condensation-preventing laminated film of the present invention may be provided with an adhesive layer 5 on the other surface of the supporting substrate layer 1 if necessary, and this adhesive layer 5 is generally used. A pressure-sensitive adhesive such as a polyacrylic acid ester-based pressure-sensitive adhesive or a silicone-based pressure-sensitive adhesive is used. However, in this case, it is preferable to selectively use an adhesive having good transparency and water whitening resistance.

[0016]

The dew condensation-preventing laminated film according to the present invention comprises forming a layer comprising a polyvinyl alcohol-based resin and an isobutylene-maleic acid-alkali metal maleate copolymer composition on a polyvinyl alcohol-based resin film. It has the effect of increasing the amount of water absorption of the resin layer and preventing dew condensation on the surface. Further, the supporting substrate layer used in the present invention acts as a support for suppressing the dimensional change when the water absorbing layer and the polyvinyl alcohol-based resin layer absorb moisture, absorb water or remove moisture, and drain water, and these absorb water. Effectively works in combination with the adhesive force of an adhesive or the like having a shear strength larger than the stretching force of the layer and the polyvinyl alcohol-based resin layer due to moisture absorption / exhaustion.

[0017]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these descriptions. (Examples 1 to 7, Comparative Examples 1 to 10) Preparation of water absorbing layer forming agent: The water absorbing layer forming agent is shown in Table 1 and Table 2.
First, polyvinyl alcohol resin (in the table,
PVA resin) was added and heated to 80 ° C. or higher to dissolve. After dissolution, change the concentration of the polyvinyl alcohol resin aqueous solution
Adjusted to 10% by weight. An isobutylene-maleic acid-sodium maleate metal salt copolymer solution (manufactured by Kuraray Co., Ltd., referred to as a copolymer in the table) was adjusted to a concentration of 10% by weight and then added to the polyvinyl alcohol resin aqueous solution. In addition, 2,4,7,9-tetramethyl-5-decyne-4,7-diol was used as the antifogging agent in the table.

Preparation of laminated film: A saponification degree shown in Table 1 and Table 2 (column of PVA resin layer) prepared by T-die melt extrusion molding method on a polyethylene terephthalate film having a thickness of 12 μm as a supporting substrate layer. Polyvinyl alcohol resin film with a degree of polymerization (thickness 50 μm)
With a urethane-based two-component reactive adhesive (polyester having hydroxyl groups at both ends, isocyanate-reactive adhesive, main agent: Takeda Pharmaceutical Co., Takelac A310, curing agent: Takenate A10, wire bar) Due to
After coating and drying the adhesive solids to a thickness of 5 μm,
The laminated film was obtained by nipping with a roll at 60 ° C. at the nip portion. The polyvinyl alcohol resin side of this laminated film was coated with a 10% by weight aqueous solution of the water absorbing layer forming agent by a wire bar so that the thickness of the coating film after drying would be the values shown in Tables 1 and 2. . After coating, it was dried at 100 ° C. for 10 minutes and further heat-treated at 170 ° C. for 30 seconds to obtain the laminated film shown in FIG.

Among the laminated films obtained, the water absorption amount was measured by the following method for each of the samples of Examples 1 to 7, Comparative Examples 1 to 2 and 8 to 10 in good condition, and the results are shown in Table 1. And also shown in Table 2. Also, on the polyethylene terephthalate side of this laminated film, a polyacrylic acid ester-based adhesive (main agent: Soken Chemical Co., Ltd., SK Dyne 1811L, curing agent: manufactured by the same company, D-90) has a solid content thickness of 20 μm. After being coated with a wire bar and dried as described above, release paper (thickness: 20 μm) was attached using a nip roll to obtain a laminate shown in FIG. This laminate is cut into 10 cm square and the thickness is 5 mm
Each sample was attached to an acrylic resin plate of No. 1 and tested for high temperature dew condensation prevention property, low temperature dew condensation prevention property and continuity of dew condensation prevention effect by the following methods, and the results are shown in Tables 1 and 2.

Measurement of water absorption: The obtained laminated film was cut into 5 cm square pieces, immersed in ion-exchanged water at 23 ° C. for 1 hour, then taken out, and the adhered water on both surfaces was sufficiently removed with a filter paper to obtain a film. The weight W ₁ of the Then, this film was dried at 110 ° C. for 3 hours, and the weight W ₂ of the film in a dried state was determined. From these values, the water absorption amount was calculated by the following formula. Water absorption = (W ₁ -W ₂ ) / 25 ・ High temperature dew condensation prevention test: 300 in a thermostatic chamber with an external temperature of 20 ° C
200 ml of deionized water kept at 40 ℃ in a beaker of ml.
It was placed and placed on the top of the beaker with the water absorbing layer side facing inward, and 15 minutes later, the state of dew condensation on the inner surface was visually observed and evaluated according to the following criteria. After the observation, the sample was immersed in ion-exchanged water at 20 ° C. for 8 days, naturally dried for 24 hours, and then subjected to the same test as above. It should be noted that ⊚ and ○ indicate that there is a dew condensation prevention effect. ⊚: No water droplets are attached to the film surface. ◯: Water droplets with a diameter of more than 10 mm adhered to a part of the film. Δ: Water droplets having a diameter of 2 to 10 mm adhered to the entire surface of the film. X: Many water droplets having a diameter of less than 2 mm adhered to the entire surface of the film.

Low-temperature dew condensation prevention test: The dew condensation state was visually observed in the same manner except that the temperature of the ion-exchanged water in the above test was set to 20 ° C., and the same criteria as above were evaluated.
After the observation, the sample was immersed in ion-exchanged water at 20 ° C. for 8 days, naturally dried for 24 hours, and then subjected to the same test as above. In addition,
About ◎ and ○, it has a dew condensation prevention effect. Sustainability test: The effect was confirmed by a joiner dew condensation prevention performance test manufactured by Fuji Tester. The conditions of the antifogging test were conducted under the conditions of a temperature of 25 ° C. on the constant temperature and humidity chamber side, a humidity of 70%, and a temperature of 5 ° C. on the constant temperature chamber side. The effect of preventing dew condensation after 2 weeks of standing was visually observed and evaluated according to the same criteria as above. In addition, ◎, ○
About the effect of preventing dew condensation. Furthermore, the presence or absence of wrinkles was also observed.

[0022]

[Table 1]

[0023]

[Table 2]

(Examples 1 to 7) In each of the laminated films obtained in the present invention, no dew condensation was observed on the inner surface of the film even under high temperature and low temperature. The effect was not lost even after immersion in ion-exchanged water for 8 days. In addition, the durability of the dew condensation prevention effect was confirmed. Furthermore, no wrinkles were observed on the film surface. (Comparative Example 1) The effect of preventing dew condensation is 2 mm in diameter on the film surface.
A large number of water droplets of less than 1 were attached and none were observed.
However, no wrinkles were found on the film surface. (Comparative Example 2) Initial effects were observed in both the high temperature dew condensation prevention property and the low temperature dew condensation prevention property, but the effect after dipping disappeared because many water droplets of less than 2 mm adhered to the entire surface of the film.
Moreover, the persistence of the effect was not recognized. However, no wrinkles were found on the film surface. (Comparative Example 3) After coating and drying, the water absorbing layer became cloudy and a transparent film could not be obtained. (Comparative Example 4) The water absorbing layer forming agent had a remarkably high viscosity, and a film having a smooth surface could not be obtained. Therefore, although the concentration of the water absorbing layer forming agent aqueous solution was further diluted by 1% by weight, a film having a smooth surface could not be obtained.

Comparative Example 5 After coating and drying, cracks occurred in the water absorbing layer of the film. (Comparative Example 6) The obtained laminated film was opaque and had poor surface smoothness. (Comparative Example 7) After coating and drying, the water absorbing layer was peeled off from the polyvinyl alcohol resin layer. (Comparative Example 8) The effect of preventing dew condensation at high temperature and at low temperature was not recognized because a large number of water droplets having a diameter of 2 to 5 mm adhered to the film surface. No sustained effect was observed.
However, no wrinkles were found on the film surface. (Comparative Example 9) The effect of preventing dew condensation is 2 to 2 mm in diameter on the film surface.
Many 5 mm water droplets adhered and were not observed. No wrinkles were found on the film surface. (Comparative Example 10) The effect of preventing initial dew condensation at high and low temperatures was excellent, but the polyvinyl alcohol-based resin layer was dissolved during immersion in ion-exchanged water and peeled off from the supporting substrate layer. Further, the polyvinyl alcohol-based resin layer swelled during the measurement of the sustaining effect, and wrinkles were observed on the film surface.

(Example 8) With respect to the laminated film obtained in Example 1, the strength of the adhesive between the polyvinyl alcohol resin layer and the polyethylene terephthalate layer before and after the durability test was determined by 90 ° and 180 ° peel strength, The results are shown in Table 3. -Measurement conditions: Tensile speed of 300 mm / min, size of 15 mm x 50 mm From this, the adhesive strength between the polyvinyl alcohol resin layer and the polyethylene terephthalate layer did not deteriorate at all even when left in the dew condensation test machine for 2 weeks.

[Table 3]

[0027]

EFFECT OF THE INVENTION The anti-condensation laminated film according to the present invention comprises a polyvinyl alcohol-based resin film, and a polyvinyl alcohol-based resin film and a water-absorbing layer comprising an isobutylene-maleic acid-alkali metal maleate mixture formed on the polyvinyl alcohol-based resin film. It is possible to prevent the dew condensation on the surface by increasing the water absorbing power on the surface of the resin film.
In addition, a water-absorbing layer and a polyvinyl alcohol-based resin layer are adhered onto a supporting substrate layer, and the water-absorbing layer is adhered to glass or the like so that the water-absorbing layer serves as a surface layer. It is possible to completely prevent wrinkles caused by swelling and stretching of the resin. The dew condensation-preventing laminated film of the present invention provided with a pressure-sensitive adhesive layer is easily attached to or peeled from the surface of glass or the like, and is excellent in convenience.

[Brief description of drawings]

1 is a longitudinal sectional view of laminated films obtained in Examples 1 to 7 and Comparative Examples 1 to 10.

FIG. 2 is a vertical cross-sectional view of the laminates obtained in Examples 1 to 7 and Comparative Examples 1, 2 and 8 to 10.

[Explanation of symbols]

1: supporting base layer, 2: adhesive layer, 3: polyvinyl alcohol resin layer, 4: water absorbing layer, 5: adhesive layer,
6: Release paper.

[Procedure amendment]

[Submission date] September 27, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Measurement of water absorption: The obtained laminated film was cut into 5 cm square pieces, immersed in ion-exchanged water at 23 ° C. for 1 hour, then taken out, and the adhered water on both surfaces was sufficiently removed with a filter paper to obtain a film. The weight W ₁ of the Then, this film was dried at 110 ° C. for 3 hours, and the weight W ₂ of the film in a dried state was determined. From these values, the water absorption amount was calculated by the following formula. Water absorption = (W ₁ -W ₂ ) /2.5×10 ^-3 ・ High temperature condensation prevention test: 300 in a thermostatic chamber with an external temperature of 20 ° C
200 ml of deionized water kept at 40 ℃ in a beaker of ml.
It was placed and placed on the top of the beaker with the water absorbing layer side facing inward, and 15 minutes later, the state of dew condensation on the inner surface was visually observed and evaluated according to the following criteria. After the observation, the sample was immersed in ion-exchanged water at 20 ° C. for 8 days, naturally dried for 24 hours, and then subjected to the same test as above. It should be noted that ⊚ and ○ indicate that there is a dew condensation prevention effect. ⊚: No water droplets are attached to the film surface. ◯: Water droplets with a diameter of more than 10 mm adhered to a part of the film. Δ: Water droplets having a diameter of 2 to 10 mm adhered to the entire surface of the film. X: Many water droplets having a diameter of less than 2 mm adhered to the entire surface of the film.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

[0022]

[Table 1]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[0023]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area C08L 23/26 LDP

Claims (1)

[Claims] 1. A polyvinyl alcohol-based resin layer is laminated on a supporting substrate layer which is water-insoluble and has a total light transmittance of 90% or more, with an adhesive layer, and a saponification degree of 95 mol% or more and a polymerization degree. 500 to 2500 polyvinyl alcohol resin (A),
A weight ratio (A) in which 25 to 50% of the carboxyl groups in the copolymer consist of an isobutylene-maleic acid-maleic acid alkali metal salt copolymer (B) in the form of an alkali metal salt.
/ (B) = 90/10 to 20/80, which is provided with a water-absorbing layer, which is a dew condensation preventing laminated film or sheet.