JP4950849B2 - Water discolorable laminate - Google Patents

Description

  The present invention relates to a water discolorable laminate. More specifically, the present invention relates to a water discolorable laminate having improved durability.

Conventionally, several proposals have been made on a discolorable laminate in which a low refractive index pigment is fixed on a support in a dispersed state in a binder resin and a porous layer having different transparency in a liquid absorption state and a non-liquid absorption state is provided. It is disclosed (for example, see Patent Document 1).
In the laminate, the lower layer is concealed when the porous layer is in a dry state (non-absorbing state), and when the porous layer absorbs water, it becomes transparent and the color tone of the lower layer can be visually recognized. It has variability.
Japanese Patent Publication No. 52-44103

  The present invention is not repeatedly scratched on the laminate, i.e., the porous layer is scratched, the thickness of the porous layer is reduced by rubbing, or peeling and the discoloration function is not deteriorated. It is an object of the present invention to provide a water discolorable laminate that satisfies practicality.

The present invention provides a porous layer having a low refractive index pigment fixed on a support in a dispersed state in a binder resin and having different transparency in a liquid-absorbing state and a non-liquid-absorbing state, and the porous layer is formed on the porous layer. Ri particulate material or a non-spherical granules name a protective layer dispersed in a binder resin, and the thickness a of the protective layer ([mu] m), a porous granules or non-spherical particulate per unit area in the protective layer body mass B (g / m ²⁾ is the requirement of water discoloration laminate satisfying the following relational expression (1) and (2).
1 + 2B ≦ A ≦ 3.5 + 2B (1)
0.5 ≦ B ≦ 2.5 (2)
Furthermore, among the granules before Symbol protective layer, the granules made of organic material occupies 10 to 100% by volume, the protective layer comprises a binder resin having a refractive index 1.45 to 1.65, an average particle It is required to be composed of a granular material having a diameter of 0.1 to 10 μm and a refractive index of 1.45 to 1.65.

  INDUSTRIAL APPLICABILITY The present invention has excellent practicality that can satisfy scratch resistance and can permanently exhibit discoloration due to the application of water without impairing the function of transparency in the liquid absorption state and non-liquid absorption state of the porous layer. A water discolorable laminate can be provided.

  The substrate is effective if it is a substrate having printability, for example, paper, synthetic paper, woven fabric, knitted fabric, braid, non-woven fabric, natural or synthetic leather, plastic, glass, ceramics, metal Wood, stone, etc. are used. The shape is preferably a planar shape, but may be an uneven shape.

The porous layer provided on the support is a layer in which a low refractive index pigment is fixed in a dispersed state together with a binder resin, and is a layer having different transparency in a dry state and a liquid absorption state.
Examples of the low refractive index pigment include silicic acid and salts thereof, barite powder, barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, talc, alumina white, magnesium carbonate, and the like. It is in the range of 1.8, and shows good transparency when water is absorbed.
Examples of the silicic acid salts include aluminum silicate, aluminum potassium silicate, sodium aluminum silicate, aluminum calcium silicate, potassium silicate, calcium silicate, calcium sodium silicate, sodium silicate, magnesium silicate, and magnesium potassium silicate.
Two or more of the low refractive index pigments can be used in combination.
The particle size of the low refractive index pigment is not particularly limited, but 0.03 to 10.0 μm is preferably used.
In addition, silicic acid is mentioned as a low refractive index pigment used suitably.
The silicic acid may be a silicic acid produced by a dry process, but a silicic acid produced by a wet process (hereinafter referred to as a wet process silicic acid) is particularly effective. To explain this point, silicic acid is amorphous. Amorphous silicic acid produced by a dry process using a gas phase reaction such as thermal decomposition of silicon halide such as silicon tetrachloride (hereinafter referred to as dry process silicic acid), and sodium silicate. It is roughly divided into those using a wet method using a liquid phase reaction such as decomposition by an acid such as a dry method, and the structure of a dry method silicic acid is different from that of a wet method silicic acid. In contrast, wet-process silicic acid has a so-called two-dimensional structure part in which silicic acid is condensed to form a long molecular arrangement.
Therefore, since the molecular structure becomes rough compared to the dry method silicic acid, when wet method silicic acid is applied to the porous layer, it is excellent in the diffused reflection of light in the dry state compared to the system using the dry method silicic acid, Therefore, it is guessed that the concealment property in a normal state becomes large.
Moreover, in the porous layer, since water is absorbed, the wet process silicic acid has more hydroxyl groups present as silanol groups on the particle surface than the dry process silicic acid, and the degree of hydrophilicity is large. Preferably used.
In addition, in order to adjust the concealability in the normal state of the porous layer and the transparency in the liquid absorption state, other general-purpose low-refractive-index pigments can be used in combination with the wet method silicic acid.

The low refractive index pigment in the porous layer depends on properties such as particle diameter, specific surface area, oil absorption, etc., in order to satisfy both the concealability in the normal state and the transparency in the liquid absorption state, preferably the coating amount is 1 to 30 g / ^{m 2,} more preferably 5 to 20 g / ^{m 2.} If it is less than 1 g / m ² , it is difficult to obtain sufficient concealability in a normal state, and if it exceeds 30 g / m ² , it is difficult to obtain sufficient transparency during liquid absorption.
The low refractive index pigment is dispersed in a vehicle containing a binder resin as a binder, applied to a translucent support, and then the volatile matter is dried to form a porous layer.
Examples of the binder resin include urethane resin, nylon resin, vinyl acetate resin, acrylic ester resin, acrylic ester copolymer resin, acrylic polyol resin, vinyl chloride-vinyl acetate copolymer resin, maleic 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 Each resin emulsion, casein, starch, cellulose derivative, polyvinyl alcohol, urea resin, phenol resin and the like can be mentioned.
The mixing ratio of the low refractive index pigment and these binder resins depends on the type and properties of the low refractive index pigment, but preferably the binder resin solid content is 0.5 to 1 part by mass with respect to 1 part by mass of the low refractive index pigment. 2 parts by mass, and more preferably 0.8 to 1.5 parts by mass. When the binder resin solid content is less than 0.5 parts by mass with respect to 1 part by mass of the low refractive index pigment, it is difficult to obtain a practical film strength of the porous layer, and the content exceeds 2 parts by mass. In this case, the water permeability into the porous layer is deteriorated.
Since the porous layer has a smaller mixing ratio of the binder resin to the colorant than a general coating film, it is difficult to obtain sufficient film strength. Therefore, in order to increase the scratch resistance, it is effective to use a nylon resin or a urethane resin among the binder resins.
Examples of the urethane resin include a polyester urethane resin, a polycarbonate urethane resin, and a polyether urethane resin, and two or more of them can be used in combination. In addition, a urethane emulsion resin in which the resin is emulsified and dispersed in water, or a colloid in which the resin is self-emulsified without the need for an emulsifier by an ionic group of the ionic urethane resin (urethane ionomer) itself and dissolved or dispersed in water. A dispersion type (ionomer type) urethane resin can also be used.
The urethane-based resin may be either an aqueous urethane-based resin or an oil-based urethane-based resin. Used for.
The urethane resin can be used alone, but other binder resins can be used in combination depending on the type of translucent support and the performance required for the film. When a binder resin other than the urethane resin is used in combination, in order to obtain a practical film strength, it is preferable to contain 30% or more of the urethane resin in a solid mass ratio in the binder resin of the porous layer.
In the binder resin, the crosslinkable resin can be further improved in film strength by adding an arbitrary crosslinking agent and crosslinking.
The binder resin has a large or small affinity with water. By combining these, the penetration time into the porous layer, the degree of penetration, and the slow speed of drying after the penetration can be adjusted. Furthermore, the said adjustment can be controlled by adding a dispersing agent and surfactant suitably.

  The porous layer is formed by screen printing, offset printing, gravure printing, coater, tampo printing, transfer printing, brush coating, spray coating, electrostatic coating, electrodeposition coating, flow coating, roller coating, dip coating, etc. It can be formed on a support.

The protective layer provided on the porous layer has water permeability for the porous layer to absorb water or dry through the layer, and has sufficient film strength and transparency as a protective layer. is necessary.
In order for the protective layer to have water permeability, it is necessary to provide a communication hole in the layer.
Further, in order to have a sufficient film strength, it is preferable to make the protective layer thicker, but if the layer is made thicker, the transparency of the layer itself is lowered, and the porous layer is in a liquid-absorbing state and a non-liquid-absorbing state. A clear color change cannot be visually recognized, and water permeability is easily lost.
In order to solve these problems, non-spherical granular material or porous granular material is included in the protective layer within a range that maintains the coating strength and transparency above a certain level, and water permeation of the protective layer is formed. Improve sexiness.
To meet the previous SL requirements, the mass B of the porous granules or non-spherical granules per unit area in the protective layer (g / m ²⁾ for there is a range, between the thickness A ([mu] m) of the protective layer The following relational expressions (1) and (2) hold.
1 + 2B ≦ A ≦ 3.5 + 2B (1)
0.5 ≦ B ≦ 2.5 (2)
If the mass B of the porous granule or non-spherical granule is less than 0.5 g / m ² , the protective layer tends to inhibit the passage of water to the porous layer, so that the color change sensitivity is reduced or the color change is difficult. Become.
On the other hand, when the mass B exceeds 2.5 g / m ² , the coating layer strength of the protective layer becomes weak, so that the function as a protective layer for the porous layer becomes poor.
Moreover, since the coating film strength of a protective layer becomes weak when the film thickness A (micrometer) of a protective layer is less than 1 + 2B, it becomes poor in the function as a protective layer with respect to a porous layer.
On the other hand, when the thickness A (μm) of the protective layer exceeds 3.5 + 2B, the protective layer easily inhibits the passage of water into the porous layer, so that the color change sensitivity is reduced or the color change is difficult.
Moreover, about binder resin which forms a protective layer, and a granular material, binder resin with a refractive index of 1.45 to 1.65, an average particle diameter of 0.1 to 10 μm, and a refractive index of 1.45 to 1.65 By using the granular material, the transparency of the protective layer is improved, and the porous layer provided in the lower layer can be observed without impairing the change in liquid absorption and non-liquid absorption.
When the refractive index of the binder resin and the refractive index of the granular material are greatly different, the protective layer becomes cloudy, and it becomes difficult to visually recognize the color change when the lower porous layer absorbs liquid and when it does not absorb liquid.
Furthermore, when the particle size of the granular material in the protective layer is large, the strength of the protective layer is reduced, and when the particle size is small, the water permeability of the protective layer is easily inhibited.

Examples of the non-spherical granular material or porous granular material include non-spherical granular materials such as flat granular materials and raspberry granular materials, and porous granular materials such as hollow particles.
The flat granular material may be a granular material obtained by squashing spherical particles.
Examples of the flat granule include a disc shape such as a circle and an ellipse, a donut shape having a through hole in the center, and a synthetic resin granule having a shape in which the center of one surface is depressed.
As the granular material, Mitsui Chemicals, trade name: Muticle PP240D (styrene resin, particle diameter 0.5 μm, refractive index 1.6), Muticle PP2000TX (styrene acrylic resin, particle diameter 0.5 μm, A refractive index of 1.6) can be exemplified.
As the raspberry-like granular material, Nippon Zeon Co., Ltd., trade name: LX407BP (styrene butadiene resin, particle diameter 0.4 μm, refractive index 1.5) can be exemplified.
The hollow particles are particles having voids inside, and have a porous outer wall.
The shape may be spherical or flat.
As the hollow particles, trade names: Ropeke HP-1055 (styrene acrylic resin, particle diameter 1 μm, refractive index 1.5), Ropeke HP-91 (styrene acrylic resin, particle diameter 1 μm, refraction) manufactured by Nippon Zeon Co., Ltd. 1.5), Ropeke OP-84J (styrene acrylic resin, particle size 0.6 μm, refractive index 1.5), Ropeke HP-433J (styrene acrylic resin, particle size 0.4 μm, refractive index 1.5),
NIPOL MH5055 (styrene acrylic resin, particle size 0.5 μm, refractive index 1.5),
Examples include trade names: SX866 (styrene acrylic resin, particle diameter 0.3 μm, refractive index 1.5) and SX8782 (styrene acrylic resin, particle diameter 1 μm, refractive index 1.5) manufactured by JSR Corporation.

As means for adhering water to the laminate, a writing or applicator having a brush or a fiber pen at the tip, a fiber or brush that contains water in the container and derives the water in the container A water applicator such as a writing instrument or applicator provided with a roller, an applicator in the form of a roller, or a stamp tool can be used.
In addition, as a preferable water adhering tool, it is a writing instrument or applicator in which water is contained in a container and a plastic porous body or a fiber processed body having continuous pores for leading out the water in the container is applied as a pen tip member. The handwriting can be easily formed and the practicality can be enhanced.
The plastic porous body or fiber processed body having continuous pores in the above may be any one that absorbs and discharges water in an appropriate amount, such as polyolefin-based, polyurethane-based, polyester-based and other various plastic continuous pores and fibers. Examples include a focused brush-like one, a fiber-processed resin-processed or heat-welded one, a felt, and a non-woven fabric. The shape and dimensions can be arbitrarily set according to the purpose.

Examples are shown below, but the present invention is not limited to these examples. In addition, the part in an Example shows a mass part.
Example 1
10 parts pink fluorescent pigment [trade name: Epocolor FP-10, manufactured by Asahi Chemical Co., Ltd.] on white synthetic paper as a support, 50 parts acrylic acid emulsion (solid part 50%), silicone-based antifoaming agent A fluorescent pink screen ink obtained by uniformly mixing and stirring 0.2 parts, 3 parts of a water-based ink thickener, 2 parts of a wetting agent, 1 part of a leveling agent, 10 parts of water, and 2.5 parts of an epoxy-based crosslinking agent. Using this, solid printing was performed with a 180 mesh screen plate to form a colored layer.
Next, 15 parts of wet-process silicic acid [trade name: Nipseal E-200A, manufactured by Nippon Silica Industry Co., Ltd.], urethane emulsion [trade name: Hydran AP-10, Dainippon Ink & Chemicals, Inc.] on the colored layer. Manufactured, solid content 30%] 50 parts, water 30 parts, silicone-based antifoaming agent 0.5 part, water-based ink thickener 3 parts, ethylene glycol 1 part, block isocyanate-based crosslinking agent 2 parts uniformly mixed and stirred Using the white screen printing ink thus formed, the entire surface was solid-printed with a 120-mesh screen plate and dried and cured at 70 ° C. for 5 minutes to form a porous layer.
Next, 4.5 parts of resin particles [Muticle PP240D, manufactured by Mitsui Chemicals, Inc.], 4.5 parts of wet method silicic acid [trade name: Cicilia 730, manufactured by Nippon Silica Industry Co., Ltd.] on the porous layer, Acrylic emulsion [trade name: NeoRez A-612, manufactured by DSM, solid content 32%] 60 parts, 0.5 part of silicone-based antifoaming agent, 3 parts of water-based ink thickener, 1 part of ethylene glycol, blocked isocyanate-based crosslinking Using a screen printing ink obtained by uniformly mixing and stirring 2 parts of the agent, solid-printed on a 180 mesh screen plate and dried and cured at 70 ° C. for 5 minutes to form a protective layer (film thickness 5 μm, granular material 1 0.5 g / m ² inclusive) to form a discolorable laminate.
In the discolorable laminate, a white porous layer was visually recognized in the dry state. When water was allowed to adhere from above the protective layer, the porous layer changed to colorless and transparent due to liquid absorption, the pink color of the colored layer was visually recognized, and the entire surface returned to a white state as the water evaporated.

Comparative Example 1
On the same support as in Example 1, the same colored layer and porous layer as in Example 1 were formed to obtain a discolorable laminate.
In the discolorable laminate, a white porous layer was visually recognized in the dry state. When water was attached, the porous layer changed to colorless and transparent due to liquid absorption, the pink color of the colored layer was visually recognized, and the entire surface returned to a white state as the water evaporated.

Comparative Example 2
On the same support as in Example 1, the same colored layer and porous layer as in Example 1 were formed.
Next, on the porous layer, 3 parts of resin particles [Muticle PP240D, manufactured by Mitsui Chemicals, Inc.], 3 parts of a wet process silicic acid [trade name: Cicilia 730, manufactured by Nippon Silica Kogyo Co., Ltd.], acrylic emulsion [ Product name: NeoRez A-612, DSM, solid content 32%] 60 parts, silicone antifoam 0.5 parts, aqueous ink thickener 3 parts, ethylene glycol 1 part, block isocyanate cross-linking agent 2 parts Using a screen printing ink that is uniformly mixed and stirred, a solid print is made on a 120-mesh screen plate and dried and cured at 70 ° C. for 5 minutes to form a protective layer (film thickness: 8 μm, granular material: 1.5 g / m ² -containing) to form a discolorable laminate.
In the discolorable laminate, a white porous layer was visually recognized in the dry state. Even when water was allowed to adhere from above the protective layer, the porous layer was poor in color change due to inhibition of liquid absorption by the protective layer.

Comparative Example 3
On the same support as in Example 1, the same colored layer and porous layer as in Example 1 were formed.
Next, on the porous layer, 8 parts of resin particles [Muticle PP240D, manufactured by Mitsui Chemicals, Inc.], 8 parts of wet process silicic acid [trade name: Cicilia 730, manufactured by Nippon Silica Industry Co., Ltd.], acrylic emulsion [ Product name: NeoRez A-612, DSM, solid content 32%] 60 parts, silicone antifoam 0.5 parts, aqueous ink thickener 3 parts, ethylene glycol 1 part, block isocyanate cross-linking agent 2 parts Using a screen printing ink that is uniformly mixed and stirred, a solid printing is performed on a 250 mesh screen plate, followed by drying and curing at 70 ° C. for 5 minutes to form a protective layer (film thickness 3 μm, granular material 1.5 g / m ² -containing) to form a discolorable laminate.
In the discolorable laminate, a white porous layer was visually recognized in the dry state. When water was allowed to adhere from above the protective layer, the porous layer changed to colorless and transparent due to liquid absorption, the pink color of the colored layer was visually recognized, and the entire surface returned to a white state as the water evaporated.

Comparative Example 4
On the same support as in Example 1, the same colored layer and porous layer as in Example 1 were formed.
Next, on the porous layer, 2 parts of resin particles [Muticle PP240D, manufactured by Mitsui Chemicals, Inc.], 2 parts of wet method silicic acid [trade name: Cicilia 730, manufactured by Nippon Silica Kogyo Co., Ltd.], acrylic emulsion [ Product name: NeoRez A-612, DSM, solid content 32%] 60 parts, silicone antifoam 0.5 parts, aqueous ink thickener 3 parts, ethylene glycol 1 part, block isocyanate cross-linking agent 2 parts Using a screen printing ink that is uniformly mixed and stirred, a solid print is made on a 250-mesh screen plate, followed by drying and curing at 70 ° C. for 5 minutes to form a protective layer (film thickness 3 μm, granular material 0.4 g / m ² -containing) to form a discolorable laminate.
In the discolorable laminate, a white porous layer was visually recognized in the dry state. Even when water was allowed to adhere from above the protective layer, the porous layer was poor in color change due to inhibition of liquid absorption by the protective layer.

Example 2
On a white synthetic paper as a support, 10 parts of a pink pigment, 50 parts of an acrylic acid emulsion (solid part 50%), 0.2 part of a silicone-based antifoaming agent, 3 parts of a water-based ink thickener, 2 parts of a wetting agent, The letter “A” was printed on a 180-mesh screen plate using a fluorescent pink screen ink in which 1 part of a leveling agent, 10 parts of water, and 2.5 parts of an epoxy crosslinking agent were uniformly mixed and stirred. .
Next, 15 parts wet-type silicic acid [trade name: Nipseal E-200A, manufactured by Nippon Silica Kogyo Co., Ltd.], urethane emulsion [trade name: Hydran AP-10, manufactured by Dainippon Ink & Chemicals, Inc.] , Solid content 30%] 50 parts, water 30 parts, silicone-based defoamer 0.5 part, water-based ink thickener 3 parts, ethylene glycol 1 part, block isocyanate-based crosslinking agent 2 parts uniformly mixed and stirred Using the white screen printing ink, solid printing was performed on the entire surface with a 120 mesh screen plate, followed by drying and curing at 70 ° C. for 5 minutes to form a porous layer.
Next, on the porous layer, 11 parts of resin particles [Muticle PP240D, manufactured by Mitsui Chemicals, Inc.], acrylic emulsion [trade name: NeoRez A-612, manufactured by DSM, solid content 32%] 60 parts, silicone 180 mesh screen ink using screen printing ink prepared by uniformly mixing and stirring 0.5 part of antifoaming agent, 3 parts of water-based ink thickener, 1 part of ethylene glycol and 2 parts of blocked isocyanate crosslinking agent A solid printing was performed with a plate to form a protective layer (film thickness 5 μm, containing granular material 1.8 g / m ² ) to obtain a discolorable laminate.
In the discolorable laminate, a white porous layer was visually recognized in the dry state. When water was allowed to adhere from above the protective layer, the porous layer changed to colorless and transparent due to liquid absorption, and the pink letter A in the lower layer was clearly visible, and the entire surface returned to a white state as the water evaporated.

Comparative Example 5
On the same support as in Example 2, the same letter “A” as in Example 2 and a porous layer were formed to obtain a discolorable laminate.
In the discolorable laminate, a white porous layer was visually recognized in the dry state. When water was attached, the porous layer changed to colorless and transparent due to liquid absorption, and the pink letter A in the lower layer was clearly visually recognized, and the entire surface returned to a white state as the water evaporated.

The table below shows the results of visual discoloration tests when each of the discolorable laminates of Examples 1 and 2 and Comparative Examples 1 to 4 is wetted with water, and the results of a scratch resistance test using a friction tester.
For the scratch resistance test, a friction tester type 2 (Gakushin Type) [manufactured by Suga Test Instruments Co., Ltd.] was used, and the upper friction piece was cotton cloth (Kanakin No. 3, JIS L 0803 compliant, JIS dyeing fastness) And the friction element was subjected to a horizontal reciprocating motion between 10 cm at a speed of 30 reciprocations per minute under a load of 700 g at a speed of 30 reciprocations per minute.
The scratch resistance test was performed in a state where the test piece was wet with water (liquid absorption state).

Discoloration test ○: Sufficient transparency.
(Triangle | delta): The color tone and pattern of a lower layer are visually recognized unclearly, and there is no practical transparency.
X: The color tone and pattern of a lower layer are not visually recognized.
Scratch resistance test ○: There is no deterioration of the film due to scratching.
(Triangle | delta): The deterioration of the film | membrane by abrasion is large and does not have practical film | membrane intensity | strength.
X: A porous layer lose | disappears by abrasion.

  As can be seen from the test results, the discolorable laminate of the present invention showed improved scratch resistance while maintaining good discoloration by wetting with water, as compared with the laminate of the comparative example.

Claims (3)

A porous layer having a low refractive index pigment fixed in a dispersed state in a binder resin and having different transparency in a liquid absorbing state and a non-liquid absorbing state is provided on the support, and the porous granular material or non-porous material is provided on the porous layer. Ri spherical granules name a protective layer dispersed in a binder resin, and the thickness a of the protective layer ([mu] m), the mass B of the porous granules or non-spherical granules per unit area in the protective layer A water discolorable laminate in which (g / m ² ) satisfies the following relational expressions (1) and (2) .
1 + 2B ≦ A ≦ 3.5 + 2B (1)
0.5 ≦ B ≦ 2.5 (2) The water discolorable laminate according to claim 1, wherein among the granules in the protective layer, the granules made of an organic material occupy 10 to 100% by volume. The protective layer is composed of a binder resin having a refractive index of 1.45 to 1.65 and a granular material having an average particle diameter of 0.1 to 10 µm and a refractive index of 1.45 to 1.65. Or the water discolorable laminated body of 2 description.