JP2003127314A - Discoloring laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discoloring laminate improving the film durability of a porous layer which becomes transparent by absorbing liquid such as water, effectively functioning without losing the hiding performance in a dried state and the transparent property in a liquid absorbed state even the repetitive use, and having excellent practicability in many fields and high commercial value. SOLUTION: In a supporting body of the discoloring laminate, the porous layer in which low reflective index pigments are adhered in a binder resin comprising an urethane resin cross-linked by a polymer containing an oxazoline group in a dispersed state is formed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a color-changing laminate. More specifically, the present invention relates to a color-changing laminate that absorbs a liquid such as water, changes into a state different from the normal state, and returns to the normal state by drying.

[0002]

2. Description of the Related Art Conventionally, a low refractive index pigment and a porous layer containing a urethane resin as a binder resin are provided on a support, and the porous layer is made transparent by absorbing a liquid, and the color tone of the lower layer is improved. There is disclosed a color-changeable layered product (Japanese Patent Laid-Open No. 11-198272). The above-mentioned discolorable laminate has excellent film durability such as washing resistance and abrasion resistance of the porous layer, and is suitable for applications in the toy field, clothing field and the like.

[0003]

The present invention can further improve the film durability of the above-mentioned porous layer containing the low-refractive-index pigment and also improve the hiding property of the porous layer.
It is intended to provide a color-changing laminate having an increased commercial value and to apply it to various fields.

[0004]

SUMMARY OF THE INVENTION The present invention comprises:
A laminate for forming a porous layer in which a low-refractive-index pigment is fixed to a binder resin in a dispersed state, wherein the porous layer is transparent or translucent in a liquid-absorbing state and the changed appearance is visualized. The requirement is for a color-changing laminate in which the binder resin of the quality layer is a urethane resin crosslinked with a polymer containing an oxazoline group. Furthermore, the solid content ratio of the urethane resin crosslinked with the polymer containing an oxazoline group in the binder resin is 30% by weight or more, and the urethane resin crosslinked with the polymer containing an oxazoline group is a urethane resin. The weight ratio of the resin to the polymer containing an oxazoline group is 100: 5 to 50, and the low refractive index pigment is fine particle silicic acid produced by a wet method.
The coating amount of the particulate silicic acid in the porous layer is 1 to 40 g /
m ² and the support is a cloth.

The porous layer in which the low refractive index pigment is fixed to the binder resin in a dispersed state has a hiding property in a normal state, that is, a white color in a dry state, and is transparent in a state in which a liquid such as water is absorbed. Alternatively, it is made semi-transparent to reveal the color tone of the lower layer. In the present invention, a urethane resin is used as the binder resin, and the urethane resin is crosslinked with a polymer containing an oxazoline group. By using a urethane-based resin crosslinked with a polymer containing an oxazoline group as the binder resin, the film strength of the porous layer can be further improved, and it can be applied to various applications requiring durability, and In addition, the hiding property in the dry state and the transparency in the liquid absorbing state are not impaired. Further, due to the improvement of the film durability, for example, when producing a laminate having a film strength equivalent to the conventional one, the addition amount of the binder resin can be reduced, and accordingly, the addition amount of the low refractive index pigment can be reduced. It is possible to increase the amount, and it is also possible to improve the whiteness (hiding power) in a dry state while maintaining the same film strength as the conventional one.

Polyurethane ester is used as the urethane resin.
Urethane resin, polycarbonate urethane resin,
There are polyether urethane resins, etc., and two or more types are used in combination.
It can also be used. Also, the resin is emulsified and dispersed in water.
Urethane emulsion resin and ionic
Ion group of urethane resin (urethane ionomer) itself
Self-emulsifies without the need for an emulsifier,
Colloidal dispersion type (ionomer type)
Urethane resin can also be used. Incidentally, the urethane
-Based resins are water-based urethane-based resins or oil-based urethane-based resins
Either can be used, but in the present invention, an aqueous solution is used.
Urethane resin, especially urethane emulsion resin,
A colloid-dispersed urethane resin is preferably used. Previous
As a polymer containing an oxazoline group, there is Japan Co., Ltd.
It is possible to use cross-linking agents manufactured and sold with catalysts.
Polymer containing oxazoline group (chemical formula: C ₇ H₁₂O
₂ ・ C₈ H₈ C_TenH_Ten・ C₆ H₆ ON)_X Water dispersion emma
Trade name: Epocros K-2010E, K
-2020E, K-2030E, or oxazoline
A product in which a group-containing polymer is dissolved in water and / or a solvent.
Name: Epocros WS-500, WS-700 can be exemplified
It

The urethane resin crosslinked with the polymer containing the oxazoline group in the porous layer has a weight ratio of the urethane resin and the polymer containing the oxazoline group of 1%.
It is preferably from 00: 5 to 50. When the amount of the polymer containing an oxazoline group is less than 5 parts by weight with respect to 100 parts by weight of the urethane resin, the crosslinking is insufficient and it is difficult to obtain desired film durability. On the other hand, if it exceeds 50 parts by weight, the amount of the urethane resin or the low refractive index pigment added is limited, so that the film durability and the hiding property may be impaired.

As the binder resin contained in the porous material, a urethane resin crosslinked with a polymer containing an oxazoline group is preferably used alone, but depending on the kind of the support and the performance required for the film. , And other binder resins can be used together. When other binder resin is used together, in order to obtain practical film strength, the binder resin of the porous layer contains a urethane resin cross-linked with a polymer containing an oxazoline group in an amount of 30% or more by solid content weight ratio. , Preferably 50% or more.

As the binder resin other than the urethane resin, nylon resin, vinyl acetate resin, acrylic ester resin, acrylic ester copolymer resin, acrylic polyol resin, vinyl chloride-vinyl acetate copolymer resin, maleic acid resin, Polyester resin, styrene resin, styrene copolymer resin, polyethylene resin, polycarbonate resin, epoxy resin, styrene-butadiene copolymer resin, acrylonitrile-butadiene copolymer resin,
Methyl methacrylate-butadiene copolymer resin, butadiene resin, chloroprene resin, melamine resin, and the above resin emulsions, casein, starch, cellulose derivative, polyvinyl alcohol, urea resin, phenol resin, epoxy resin and the like can be mentioned. The binder resin is appropriately selected depending on the properties of the support. For example, when the support is a cloth, nylon resin or the like is preferably used in addition to urethane resin.

The mixing ratio of the binder resin and the low refractive index pigment depends on the type and properties of the low refractive index pigment.
The binder resin solid content is preferably 0.5 to 2 parts by weight with respect to 1 part by weight of the low refractive index pigment, and more preferably,
It is 0.8 to 1.5 parts by weight. When the binder resin solid content is less than 0.5 parts by weight with respect to 1 part by weight of the low refractive index pigment, it is difficult to obtain a practical film strength of the porous layer, and when it exceeds 2 parts by weight. In addition, the permeability of the liquid into the porous layer becomes poor. The binder resin has different affinity with water, but by combining these, the penetration time into the porous material, the degree of penetration, and the slowness of drying after penetration can be adjusted. Furthermore, the above-mentioned adjustment can be controlled by appropriately adding a dispersant.

Examples of the low refractive index pigment include fine particle silicic acid, barite powder, precipitated barium sulfate, barium carbonate,
Precipitating calcium carbonate, gypsum, clay, talc, alumina white, basic magnesium carbonate and the like are mentioned, and these have a refractive index in the range of 1.4 to 1.7 and have good transparency when absorbing water or the like. Is shown. The particle size of the low refractive index pigment is not particularly limited, but is 0.03
Those having a thickness of up to 10.0 μm are preferably used. The low refractive index pigments may be used in combination of two or more kinds. Incidentally, as the low refractive index pigment which is preferably used, fine particle silicic acid can be mentioned. Particulate silicic acid is produced as an amorphous amorphous silicic acid, and according to its production method, a dry method using a gas phase reaction such as thermal decomposition of silicon halide such as silicon tetrachloride (hereinafter referred to as dry method fine particle silicic acid). (Hereinafter referred to as “wet method fine particle silicic acid”) and a wet method using a liquid phase reaction such as decomposition with an acid such as sodium silicate (hereinafter referred to as “wet method fine particle silicic acid”), and either can be used. When the wet method fine particle silicic acid is used, since the hiding property in the normal state is larger than that of the dry method fine particle silicic acid system, it is possible to increase the mixing ratio of the binder resin to the fine particle silicic acid, and thus the porous layer Since it can improve the film strength of, it is more preferably used. As described above, wet-process fine particle silicic acid is preferable as the fine particle silicic acid used for satisfying the hiding property of the porous layer in the normal state. This is because the dry method fine particle silicic acid and the wet method fine particle silicic acid have different structures, whereas the dry method fine particle silicic acid forms a three-dimensional structure in which silicic acid is closely bonded as shown below. ,

[Chemical 1] The wet method fine particle silicic acid has a so-called two-dimensional structure portion in which silicic acid is condensed to form a long molecular array, as shown below. Therefore, since the molecular structure becomes coarser as compared with the dry method fine particle silicic acid, when the wet method fine particle silicic acid is applied to the porous layer, the light in the dry state is compared with the system using the dry method fine particle silicic acid. It is presumed that the diffuse reflection property of is excellent, and therefore the hiding property in the normal state is increased.

[Chemical 2] Further, since the low refractive index pigment contained in the porous layer is mainly water as a liquid absorbing medium, the wet method fine particle silicic acid exists as a silanol group on the particle surface as compared with the dry method fine particle silicic acid. It has a large number of hydroxyl groups, and therefore has suitable hydrophilicity, and is therefore preferably used.

When the wet method fine particulate silicic acid is used as a low refractive index pigment, the type, particle diameter,
Specific surface area, will depend on the nature of the oil absorption, etc., in order to satisfy both the transparency in the hiding properties and liquid absorption state at normal, it applied amount is 1g / m ² ~40g / m ² by weight, more preferably from ^{5g / m 2 ~30g / m 2} . If it is less than 1 g / m ² , it is difficult to obtain sufficient hiding power under normal conditions, and if it exceeds 40 g / m ² , it is difficult to obtain sufficient transparency when absorbing liquid. The low refractive index pigment is dispersed in a vehicle containing a binder resin as a binder, applied to an object, and then volatile components are dried to form a porous layer.

In the porous layer formed as described above, conventionally known titanium dioxide-coated mica, iron oxide-titanium dioxide-coated mica, iron oxide-coated mica, guanine, sericite, basic lead carbonate, A metallic luster pigment such as acid lead arsenate or bismuth oxychloride may be added, or general dyes or pigments, fluorescent dyes or pigments may be added to diversify the color change.
Further, a reversible thermochromic material that reversibly changes color due to temperature change can be contained in the porous layer, or a reversible thermochromic layer containing a reversible thermochromic material can be provided.

The reversible thermochromic material used for forming the reversible thermochromic layer includes, for example, an electron-donating color-developing organic compound, an electron-accepting compound, and an organic compound that reversibly causes a color reaction between the both. A reversible thermochromic composition containing three components of a compound medium, liquid crystal, Ag ₂ HgI ₄ , Cu ₂ HgI _4, etc. are used. A reversible thermochromic composition containing three components of an organic compound medium that reversibly causes a color reaction with the electron-donating color-developing organic compound and the electron-accepting compound is specifically disclosed in JP-B-51-44706. Publication, Japanese Patent Publication 1-293
No. 98, Japanese Patent Publication No. 4-17154, etc. are mentioned. The reversible thermochromic composition containing three components of the organic compound medium that reversibly causes a color reaction with the electron-donating color-developing organic compound and the electron-accepting compound is effective even as it is, It is preferable to use as a microcapsule pigment encapsulated in microcapsules, which can form a chemically and physically stable pigment, and has a particle diameter of 0.1 to 100 μm, preferably 0.1 to 50 μm, and more preferably 0.1. The range of ˜30 μm satisfies the practicality. Microencapsulation can be carried out by the conventionally known interfacial polymerization method, in situ polymerization method, submerged curing coating method, phase separation method from aqueous solution, phase separation method from organic solvent, melt dispersion cooling method, air suspension method. There are a coating method, a spray drying method and the like, which are appropriately selected depending on the application. Further, the surface of the microcapsules may be provided with a secondary resin film depending on the purpose to impart durability, or the surface characteristics may be modified for practical use.

The reversible thermochromic composition (preferably microcapsule pigment) is dispersed in a vehicle containing a resin which is a film-forming material and applied as a coloring material such as ink or paint to form a reversible thermochromic layer. Can be formed. Further, it can be applied as a layer having a reversible thermochromic layer by itself by being dispersed in a thermoplastic resin or a thermosetting resin and molded into a sheet shape or other various forms. It is also possible to mix non-thermochromic general dyes and pigments, fluorescent dyes and pigments in the thermochromic layer to discolor various colors.

The support may be woven fabric, knitted fabric, braid,
Other than cloth such as non-woven fabric, paper, synthetic paper, synthetic leather, leather, plastic, glass, ceramics, wood, stone, etc. can be mentioned, and all are effective. When using a cloth as a support,
From the viewpoint of film forming property of the porous layer, a woven fabric having an excellent smoothness on the surface of the fabric is preferably used. When the smoothness of the surface of the fabric is poor, or when the permeability of ink or the like into the fabric is large and the film forming property of the porous layer is poor, the fabric is subjected to a treatment such as water repellency treatment. The film forming property of the porous layer can be improved.

As the method for forming the above-mentioned porous layer, conventionally known coating methods such as screen printing, offset printing, gravure printing, coater, tampo printing, printing means such as transfer, brush coating, spray coating, static coating, etc. Electric painting,
Means such as electrodeposition coating, flow coating, roller coating, dip coating and the like can be mentioned.

Further, if necessary, a non-color-changing ink containing a general dye or pigment, a fluorescent dye or a pigment is applied to the color-changing laminate of the present invention to form a non-color-changing layer, or titanium dioxide-coated mica or iron oxide. -A metallic luster layer can be provided by applying an ink containing a metallic luster pigment such as titanium dioxide-coated mica, iron oxide-coated mica, guanine, sericite, basic lead carbonate, lead acid arsenate, bismuth oxychloride. Also, a protective layer and a light stabilizer layer can be provided as appropriate. Specifically, the light stabilizer layer is a UV absorber, an antioxidant, an antioxidant,
Singlet oxygen quencher, superoxide anion quencher,
It is a layer in which a light stabilizer selected from an ozone decolorizer, a visible light absorber and an infrared absorber is fixed in a dispersed state. If necessary, an antistatic agent, a polarity imparting agent, a thixotropic agent, an antifoaming agent, etc. may be added to each layer to improve the function.

Next, the constitution of the discolorable laminate of the present invention and changes in the dry state (non-absorption state) and the state in which water or the like is absorbed will be described. As described above, the color-changing laminate of the present invention is a porous layer containing a low-refractive-index pigment and a binder resin which are laminated on a support, which has a hiding property when dried to conceal the lower layer, The lower layer is exposed by making it transparent or translucent while absorbing water or the like. Therefore, even if the support has a single color, by partially wetting the porous layer with a brush, a brush, a pen, a stamp, etc., the wetted part becomes transparent or translucent and the color tone of the lower layer is visually recognized. The desired image can be displayed. When the water in the porous layer evaporates and dries, the porous layer again hides the lower layer and returns to the original state. Therefore, it is of course possible to provide a pattern or a multicolored pattern on the support and conceal it with the porous layer, and of course, to make the pattern related to or integrated with the pattern visually recognized in the state where the porous layer is made transparent by the liquid absorption. It is also possible to provide it on a layer so that an image in which the above-mentioned symbols are combined can be visually recognized in a liquid absorbing state. It is also possible to form a pattern with a porous layer that is colored by adding general pigments, etc., so that the porous layer absorbs liquid and the color tone of the support seen through makes it invisible. In addition, the color tone of the porous layer can be set. Further, as a transparent support, for example, a transparent three-dimensional object may be provided with a porous layer, and the porous layer may be transparent by absorbing liquid to allow the three-dimensional object itself to be seen through.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the above laminated structure, the porous layer may be a pattern layer of characters, symbols, figures, etc., if necessary. In addition, intervening a reversible thermochromic layer or non-color-changing layer,
It may be provided on the upper layer, and similarly, it may be a pattern layer of characters, symbols, figures and the like. The color-changing laminate of the present invention is not limited to a flat shape, and various shapes such as a linear shape, an uneven shape, and a three-dimensional shape are effective. Specific embodiments of the discolorable laminate, for example, stuffed animals, dolls, doll costumes such as raincoats, doll accessories such as umbrellas and bags, water gun targets, models simulating cars and ships, Boards and other toys that show traces of human and doll handprints, footprints, etc., water brush paper, water brush sheets and other learning equipment, stationery, dresses, swimwear, raincoats and other clothing, rain shoes and other shoes, waterproofing Book, printed matter such as calendars, stamp cards, puzzles, recreational equipment such as various games, wetsuits, floating bags, swimming or diving equipment such as swimming floats, coasters, kitchen equipment such as cups, Other examples include umbrellas, artificial flowers, and winning lottery tickets. It can also be applied as various indicators, such as piping,
Detection of liquid leaks in pipes, water tanks, tanks, etc., detection of water wetting in transportation and storage areas of water-inhibiting chemicals, detection of dew condensation, rainfall, etc. Examples include detection of water content in soil.

[0021]

EXAMPLES Examples will be shown below. In addition, the part in an Example shows a weight part. Example 1 10 parts of a pink fluorescent pigment [trade name: Epocolor FP-10, manufactured by Nippon Shokubai Co., Ltd.] on a white nylon taffeta cloth as a support, an aqueous acrylic acid emulsion resin (trade name: Movinyl 727, Clariant) Polymer company,
Solid content 50%) 50 parts, silicone antifoaming agent 0.2 parts,
A fluorescent pink screen printing ink prepared by uniformly mixing and stirring 5 parts of a thickener, 1 part of a leveling agent, 10 parts of water, and 2.5 parts of an epoxy-based crosslinking agent, using a screen plate of 150 mesh, Solid printing was performed on both front and back surfaces of the support, followed by drying and curing at 130 ° C. for 5 minutes to form a non-color-change layer. Then, on the non-color-changing layer, a wet method fine particle silicic acid [trade name: Nipseal E-200 as a low refractive index pigment is used.
A, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, water-based urethane resin (trade name: HYDRAN AP-1 as a binder resin
0), polyester-based urethane resin [manufactured by Dainippon Ink and Chemicals, Inc., solid content: 30%] 50 parts, water 30 parts, silicone defoamer 0.5 part, water-based ink thickener 3 parts, ethylene A white screen printing ink obtained by uniformly mixing and stirring 1 part of glycol and 3 parts of a crosslinking agent [oxazoline group-containing polymer, trade name: Epocros WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content 25%]. A 180-mesh screen plate was used for solid printing on the entire surface, followed by drying and curing at 130 ° C. for 5 minutes to form a white porous layer in the dried state to obtain a color-change laminate.

The color-changing laminate had a white color in a dry state to sufficiently conceal the lower layer, and when it was wet with water, the transparency was excellent, and the fluorescent pink color was clearly visible. or,
When the discolorable laminate wet with water was left at room temperature, it gradually returned from fluorescent pink to white as the water evaporated, and returned to the original white when returned to the dry state. The discoloration laminate 1 was subjected to a rubbing resistance test using the following friction tester, and as a result, no deterioration of the coating film was observed in the rubbing resistance test of 30 times both during liquid absorption and during drying.

Example 2 15 parts of wet-process fine particle silicic acid [trade name: Nipseal E-200A, manufactured by Nippon Silica Industry Co., Ltd.] was used as a component in the white screen printing ink for forming a porous layer of Example 1. ,
25 parts of water-based urethane resin [trade name: Hydran AP-10, manufactured by Dainippon Ink and Chemicals, Inc., solid content 30%]
Aqueous acrylic acid emulsion resin (Brand name: Movinyl 727, manufactured by Clariant Polymer, solid content 50%) 1
5 parts, 40 parts of water, 0.5 part of silicone antifoaming agent, 3 parts of thickening agent for water-based ink, 1 part of ethylene glycol, crosslinking agent [oxazoline group-containing polymer, trade name: Epocros W
S-700, manufactured by Nippon Shokubai Co., Ltd., solid content 25%].
A color-change laminate was obtained in the same manner except that the amount was 5 parts.

Similar to Example 1, the color-changing laminate exhibited a white color in a dry state to sufficiently conceal the lower layer, and also had excellent transparency when wet with water, and a bright fluorescent pink color. Was seen by. The discoloration-resistant laminate was subjected to a scratch resistance test using the following friction tester, and as a result, no deterioration of the coating, which is a problem in practical use, was observed in the scratch resistance test of 30 times during both liquid absorption and drying. It was

Example 3 The components of the printing ink for a white screen for forming the porous layer of Example 1 were added with 15 parts of wet process fine particle silicic acid [trade name: Nipseal E-200A, manufactured by Nippon Silica Industry Co., Ltd.]. 15 parts of water-based urethane resin [trade name: Hydran AP-10, manufactured by Dainippon Ink and Chemicals, Inc., solid content: 30%], water-based acrylic acid emulsion resin (trade name: Movinyl 7)
27, manufactured by Clariant Polymer, solid content 50%) 21
Parts, water 44 parts, silicone antifoaming agent 0.5 parts, water-based ink thickener 3 parts, ethylene glycol 1 part, crosslinking agent [oxazoline group-containing polymer, trade name: Epocros WS-
700, manufactured by Nippon Shokubai Co., Ltd., solid content 25%] 1.35
A color-change laminate was obtained in the same manner except that the parts were used.

Similar to Example 1, the color-changing laminate exhibited a white color in a dry state to sufficiently conceal the lower layer, and also had excellent transparency when wetted with water, and a bright fluorescent pink color. Was seen by. As a result of a scratch resistance test using the friction tester described below, the discoloration-resistant laminate was not found to be a practical problem in deterioration of the coating in the scratch resistance test 30 times both during liquid absorption and during drying.

Example 4 The components of the white screen printing ink for forming the porous layer of Example 1 were mixed with 20 parts of wet process fine particle silicic acid [trade name: Nipseal E-200A, manufactured by Nippon Silica Industry Co., Ltd.]. Water-based urethane resin [Brand name: Hydran AP-10, polyester-based urethane resin [Dainippon Ink and Chemicals, Inc., solid content 30%] 50 parts, water 3 as binder resin
0 part, 0.5 part of silicone-based defoaming agent, 3 parts of thickener for water-based ink, 1 part of ethylene glycol, cross-linking agent [oxazoline group-containing polymer, trade name: Epocros WS-700,
A discolorable laminate was obtained in the same manner except that the amount was 3 parts, manufactured by Nippon Shokubai Co., Ltd., solid content 25%.

Similar to Example 1, the color-changing laminate exhibited a white color in a dry state so that the lower layer was more concealed than in Example 1, and when it was wet with water, a fluorescent pink color became clear. Was seen by. The discoloration-resistant laminate was subjected to a scratch resistance test using the following friction tester, and as a result, no deterioration of the coating, which is a problem in practical use, was observed in the scratch resistance test of 30 times during both liquid absorption and drying. It was

Example 5 Pink fluorescent pigment [trade name: Epocolor FP-10, manufactured by Nippon Shokubai Co., Ltd.] 10 on white synthetic paper as a support
Part, water-based acrylic acid emulsion resin (trade name: Movinyl 727, manufactured by Clariant Polymer, solid content 50)
%) 50 parts, silicone antifoaming agent 0.2 parts, thickener 5
Parts, 1 part of a leveling agent, 10 parts of water, 2.5 parts of an epoxy-based cross-linking agent are uniformly mixed and stirred, and a fluorescent pink screen printing ink is used. Solid printing on both sides 1
A non-color-change layer was formed by drying and curing at 30 ° C. for 5 minutes.
Then, on the non-color-changing layer, a blue dispersion pigment [trade name: Sundai Super BLUE GLL, manufactured by Sanyo Dye Co., Ltd.]
1 part, as a low-refractive-index pigment, wet-process fine particle silicic acid [trade name: Nipseal E-200A, Nippon Silica Industry Co., Ltd.
15 parts, aqueous urethane resin as binder resin [polycarbonate-based urethane resin, trade name: Neotan UE-1300, Dainippon Ink and Chemicals, Inc., solid content 40%] 37.5 parts, water 30 parts, silicone 0.5 parts antifoaming agent, 3 parts thickener for water-based ink, 1 part ethylene glycol, cross-linking agent [oxazoline group-containing polymer, trade name: Epocros WS-700, manufactured by Nippon Shokubai Co., Ltd., solid content 25% ] Solid printing was performed using a 120 mesh screen plate with a blue screen printing ink obtained by uniformly mixing and stirring 3 parts, dried at 80 ° C. for 5 minutes and cured, and a pale blue porous layer in a dried state. Was formed to obtain a discolorable laminate. The discolorable laminate exhibited a light blue color in a dry state, and when it was wet with water, a purple color was visually recognized. Further, when the discolorable laminate wet with the water is left at room temperature,
As the water evaporated, the pink color of the non-color-changing layer and the blue color of the porous layer gradually changed from purple, which changed to purple, to pale blue, and when it returned to the dry state, it returned to the original pale blue. As a result of a scratch resistance test with the following friction tester, no deterioration of the coating was observed in the discoloration-resistant laminate in a scratch resistance test of 30 times during both liquid absorption and drying.

Comparative Example 1 The cross-linking agent of the white screen printing ink for forming the porous layer of Example 1 was changed to a blocked isocyanate cross-linking agent [trade name: NK Linker BX, Shin-Nakamura Chemical Co., Ltd.]. A color-change laminate was obtained in the same manner except for the above. Similar to Example 1, the color-changing laminate exhibited a white color in a dry state to sufficiently conceal the lower layer, and was excellent in transparency when wet with water, and the fluorescent pink color was clearly visible. It was

Comparative Example 2 The cross-linking agent of the printing ink for a white screen for forming the porous layer of Example 2 was changed to a blocked isocyanate cross-linking agent [trade name: NK Linker BX, manufactured by Shin Nakamura Chemical Co., Ltd.]. A color-change laminate was obtained in the same manner except for the above. Similar to Example 2, the color-changing laminate had a white color in a dry state to sufficiently conceal the lower layer, and also had excellent transparency when wet with water, and the fluorescent pink color was clearly visible. It was

Comparative Example 3 The cross-linking agent of the white screen printing ink for forming the porous layer of Example 3 was changed to a blocked isocyanate cross-linking agent [trade name: NK Linker BX, manufactured by Shin-Nakamura Chemical Co., Ltd.]. A color-change laminate was obtained in the same manner except for the above. Similar to Example 3, the color-changing laminate exhibited a white color in a dry state to sufficiently conceal the lower layer, and also had excellent transparency when wet with water, and the fluorescent pink color was clearly visible. It was

Comparative Example 4 The cross-linking agent of the white screen printing ink for forming the porous layer of Example 4 was changed to a blocked isocyanate cross-linking agent [trade name: NK Linker BX, manufactured by Shin-Nakamura Chemical Co., Ltd.]. A color-change laminate was obtained in the same manner except for the above. Similar to Example 4, the discolorable laminate had a white color in a dry state to sufficiently conceal the lower layer, and also had excellent transparency when wet with water, and a fluorescent pink color was clearly visible. It was

Comparative Example 5 A cross-linking agent for a screen printing ink for forming a porous layer of Example 5 is blocked with an isocyanate cross-linking agent [trade name: N
K Linker BX, manufactured by Shin-Nakamura Chemical Co., Ltd.] was obtained in the same manner, except that a color-change laminate was obtained. The discolorable laminate 1 had a light blue color in a dry state, and a purple color was visually recognized when wet with water.

Scratch resistance test The scratch resistance of the porous layers of the laminates obtained in Examples 1-5 and Comparative Examples 1-5 was tested as follows. Test method Using a friction tester type 2 (Gakushin type) [manufactured by Suga Tester Co., Ltd.], a cotton cloth (Kanakin No. 3, JIS L) is used for the upper friction element.
0803 standard, JIS dyeing fastness test) was attached, and the test was conducted by horizontally reciprocating the friction member on the color-change laminate at a rate of 30 reciprocations per minute for 10 cm under a load of 700 g. The scratch resistance test was performed in a dry state of the laminate and a wet state of the laminate (absorption state). The results of the abrasion resistance test of the porous layers of Examples 1 to 5 and Comparative Examples 1 to 5 by using a friction tester are shown below (the number of times of abrasion in the table indicates the number of reciprocations of the friction element).

[0036]

[Table 1]

Evaluation of scratch resistance ⊚: No deterioration of the film due to scratching. ◯: The film has a slight deterioration of the film due to abrasion, but has practically no problem. Δ: The film is largely deteriorated by rubbing and has no practical film strength. X: The porous layer disappears due to abrasion.

As can be seen from the test results, the discolorable laminate of the present invention showed better scratch resistance than the laminate of the comparative example.

Transparency-Hiding Test The non-discoloring layer in the dry state of the laminates of Examples 1 and 4 and Comparative Examples 1 and 4 and the transparency (non-discoloring state) in the state of being wet with water (absorption state) The visibility of the layer) is visually evaluated, and the measured values of tristimulus values X, Y and Z in the CIE color system are shown in the table. The tristimulus values X, Y, and Z were measured using a color difference meter TC-3600 (manufactured by Tokyo Denshoku Co., Ltd.).

[0040]

[Table 2]

The following is a description of the symbols for visually evaluating the concealing property of the porous layer in a dry state. In addition,
The transparency when the porous layer was wet with water was such that there was practically no problem. Evaluation of concealing property in dry state A: Has sufficient concealing property. ◯: The hiding property has no practical problem.

[0042]

INDUSTRIAL APPLICABILITY Since the present invention uses the urethane resin cross-linked with the polymer containing the oxazoline group in the porous layer, the coating durability of the porous layer is further improved and the resin is dried even after repeated use. Effectively functioning without compromising the hiding power and transparency in the liquid absorbing state, the toy field,
The present invention aims to provide a color-changing laminate having a high commercial value, which is excellent in practical use in various fields such as the decoration field and the design field, and to be applied and expanded to various fields.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F100 AA03B AK01B AK51B AT00A                       BA02 BA07 CA13B DE01B                       DG11A DJ10B EH46B GB84                       GB90 JN01 JN02 JN18B                       JN28 YY00B                 4J039 AE04 BA22 BE01 FA03

Claims (6)

[Claims] 1. A porous layer in which a low-refractive-index pigment is fixed to a binder resin in a dispersed state is formed on a support, and the porous layer is transparent or translucent in a liquid-absorbing state and changes in appearance. A color-changing laminate in which the binder resin of the porous layer is a urethane resin cross-linked with a polymer containing an oxazoline group. 2. The discolorable laminate according to claim 1, wherein a solid content ratio of the urethane resin crosslinked with the polymer containing an oxazoline group in the binder resin is 30% by weight or more. 3. The discolorable laminate according to claim 1, wherein the urethane resin cross-linked with the polymer containing an oxazoline group has a weight ratio of the urethane resin and the polymer containing an oxazoline group of 100: 5 to 50. body. 4. The color-changing laminate according to claim 1, wherein the low-refractive-index pigment is fine particle silicic acid produced by a wet method. 5. The discolorable laminate according to claim 4, wherein the coating amount of the particulate silicic acid in the porous layer is 1 to 40 g / m ² . 6. The support according to claim 1, which is a cloth.
The discolorable laminate according to any one of 1.