JP7342625B2 - Card oversheet and card - Google Patents

Description

The present invention relates to an oversheet for cards such as magnetic cards and IC cards, and cards, and particularly to an oversheet for cards that has good adhesion to printing ink, and a card in which this oversheet is laminated.

Magnetic cards and IC cards are generally manufactured by printing on a white resin sheet called a core sheet, then laminating a transparent oversheet on top of the printed surface to protect it and bonding it under heat. was common.

In recent years, these cards have come to be used in harsh environments such as in-vehicle equipment, so the core sheet and oversheet that make up the card are made of materials other than polyvinyl chloride, which has traditionally been commonly used. , polyester resins and polycarbonates, which have excellent durability, have come to be used.

When printing on core sheets, in addition to silk printing, which has been traditionally used, it has quick hardening and excellent reproducibility of fine patterns, lines, letters, gradations, etc., and is compatible with the diversification of card designs. Offset printing has been adopted, and the entire surface of the core sheet is increasingly being printed.
The ink used for this offset printing is an ultraviolet curable ink whose main ingredients are epoxy acrylate, polyester acrylate, polyurethane acrylate, etc., and when solid printing is performed on the entire surface of the core sheet with these inks, it is difficult to print from polyester resin or polycarbonate. There was a problem that the thermocompression bondability with the oversheet was poor, making it difficult to stack the oversheet.

To solve this problem, a heat-sensitive adhesive layer mainly composed of polyamide resin is formed on one side of the oversheet, and the oversheet is laminated by thermocompression bonding to the printed side of the core sheet. A method has been proposed (Patent Document 1).
In addition, heat-sensitive adhesives can be made of polyurethane resins and ethylene-vinyl acetate copolymer resins, or mixed resins of polyurethane resins and acrylic resins, which are expected to have particularly good adhesion with urethane-based ultraviolet curable inks. An oversheet with an adhesive has been proposed (Patent Document 2).

Japanese Patent Application Publication No. 2003-96416 Japanese Patent Application Publication No. 2002-146305

When the heat-sensitive adhesive-attached oversheet proposed in Patent Document 1 and Patent Document 2 is thermocompression bonded to the printed surface of the core sheet, there are problems with securing initial adhesive strength and maintaining adhesive strength over a short period of time. do not have. However, in environmental tests expected for use in in-vehicle equipment, for example, in high-temperature, high-humidity environments such as 75°C and 90% RH, adhesive strength decreases due to deterioration of the adhesive. Not only may it not be possible to maintain the necessary adhesive strength, but also discoloration may occur due to deterioration of the adhesive, which may impair the visibility of fine patterns, lines, characters, etc. on the printed surface. was there.

Therefore, the object of the present invention is to have sufficient adhesion even when solid printing is performed on the entire surface of the core sheet with ultraviolet curable ink, and to have excellent durability, for example, even in a high temperature and high humidity atmosphere as described above. To provide a card oversheet provided with a heat-sensitive adhesive layer capable of exhibiting high properties, and a card laminated with this oversheet.

The present invention has a structure in which a heat-sensitive adhesive layer is provided on one surface of a base sheet, and the heat-sensitive adhesive layer is made of an adhesive resin containing a polyurethane resin and/or a polyamide resin, and a carbodiimide resin. The present invention provides an oversheet for a card, which is characterized by containing a compound as a main component.

The card oversheet provided by the present invention is provided with a heat-sensitive adhesive layer on one side of a base sheet, the main component of which is an adhesive resin composition containing a specific adhesive resin and a carbodiimide compound. The heat-sensitive adhesive layer has good adhesion strength to the printed surface on the sheet that makes up the card, the so-called core sheet. It has sufficient adhesion even when used. Moreover, it exhibits excellent durability, even under high temperature and high humidity atmospheres as mentioned above, and can maintain the necessary adhesive strength even when exposed to such high temperature and high humidity environments. Alternatively, discoloration due to adhesive deterioration can be prevented.
Therefore, since the card oversheet provided by the present invention can suitably protect the printed surface of the card, it can be used for, for example, bank cards, cash cards, credit cards, ID cards, and transportation such as trains and buses. It is possible. Furthermore, it is possible to provide a card whose card oversheet does not easily peel off even when the card is left in a high-temperature atmosphere in the summer, for example, inside a car.

1 is a cross-sectional view schematically showing a configuration example of one embodiment of a card of the present invention.

Hereinafter, the present invention will be described in detail based on embodiments of the invention. However, the present invention is not limited to the embodiments described below, and can be implemented with arbitrary modifications within the scope of the gist of the present invention.

In the present invention, the term "film" includes a "sheet," and the term "sheet" also includes a "film."
In addition, in the present invention, when expressed as "X to Y" (X, Y are arbitrary numbers), unless otherwise specified, it means "more than or equal to X and less than or equal to Y", and "preferably greater than X", "preferably It includes the meaning of "less than". Even when expressed as "more than or equal to X" or "less than or equal to Y" (X and Y are arbitrary numbers), it includes the meanings of "preferably larger than X" and "preferably smaller than Y."

In the present invention, the term "polymer alloy" refers to a multicomponent material in which two or more types of polymer compounds are mixed or mixed and partially chemically bonded (crosslinked, etc.).

<<Oversheet for this card>>
A card oversheet (referred to as "main card oversheet") according to an embodiment of the present invention has a structure in which a heat-sensitive adhesive layer is provided on one surface of a base sheet.

<Base material sheet>
The base sheet constituting the card oversheet can be made of conventionally known materials. Among these, sheets whose main component is one selected from the group consisting of hard vinyl chloride, polyester resins, polycarbonate, and polymer alloys of polyester resins and polycarbonates are preferred from the viewpoint of use.
In this case, the "main component resin" refers to 50% by mass or more, preferably 75% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass of the resin components constituting the base sheet. This means that the resin accounts for particularly preferably 95% by mass or more (the upper limit is 100% by mass).

(Polyester resin)
As the polyester resin that can be used for the base sheet, a dehydrated condensate of an aromatic dicarboxylic acid component and a diol component can be preferably mentioned. Among these, preferred are those that have low crystallinity and do not cause cloudiness or poor fusion due to crystallization even when subjected to practical heat processing such as press fusion.

Specific examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, adipic acid, naphthalene dicarboxylic acid, and the like. When using terephthalic acid as the aromatic dicarboxylic acid, a portion of the terephthalic acid may be replaced with "another dicarboxylic acid".
Examples of the "other dicarboxylic acids" include oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, neopentylic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, p-oxybenzoic acid, etc. be able to.
Note that the other dicarboxylic acid component used may be one type or a mixture of two or more types, and the amount of the other dicarboxylic acid to be substituted can also be selected as appropriate.

Specific examples of the diol component include ethylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, and the like. When using ethylene glycol as the diol, a part of the ethylene glycol may be replaced with "another diol".
The "other diols" include propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, neopentyl glycol, polyalkylene glycol, 1,4-cyclohexanedimethanol, glycerin, pentaerythritol, trimethylol, Examples include methoxypolyalkylene glycol.
The other diol component used may be one type or a mixture of two or more, and the amount of the other diol to be substituted can also be selected as appropriate.

As a specific example of the polyester resin, for example, polyethylene terephthalate, which is obtained by condensation polymerization of terephthalic acid and ethylene glycol, is preferable from the viewpoint of cost. Further, in the polyethylene terephthalate, a copolyester containing a dicarboxylic acid component other than terephthalic acid and/or a diol component other than ethylene glycol can also be preferably used.

The copolymerized polyester has a dicarboxylic acid component in which 60 mol% or more of the dicarboxylic acid component is terephthalic acid, the remaining dicarboxylic acid component is substituted with another dicarboxylic acid component, and 60 mol% or more of the diol component is ethylene. Examples include copolymerized polyesters formed by condensation polymerization of glycol and a diol component in which the remaining diol component is substituted with another diol component.

A particularly preferred copolyester is a substantially amorphous aromatic polyester resin in which about 30 mol % of the ethylene glycol in polyethylene terephthalate is replaced with 1,4-cyclohexanedimethanol. Such an aromatic polyester resin is commercially available, for example, under the trade name "PET-G" manufactured by Eastman Chemical Company.

The polyester resin may be a mixture of polyethylene terephthalate and the above copolyester.
However, when using a copolymerized polyester, care must be taken because the glass transition temperature and tensile modulus of the sheet change greatly depending on the selection and content of copolymerized components.

(polycarbonate)
The polycarbonate that can be used for the base sheet means a resin composition whose main component is polycarbonate.
The main component in this case means the resin with the highest mass percentage among the resins constituting the resin composition, and is 50% by mass or more, preferably 75% by mass or more of the resin constituting the resin composition. The content is more preferably 85% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more (the upper limit is 100% by mass).
Examples of resins that can be mixed with polycarbonate, which is the main component, include PET-G.

(Polymer alloy of polyester resin and polycarbonate)
As a polymer alloy of polyester resin and polycarbonate that can be used for the base sheet, for example, the polyester resin is PET-G or polybutylene terephthalate (hereinafter referred to as "PBT"), and this and the above-mentioned A preferred example is a polymer alloy with polycarbonate.
In this case, PBT is a dehydrated condensate of terephthalic acid and 1,4-butanediol, and may be a homopolymer or a copolymer.

In this polymer alloy, the composition ratio of the polyester resin and polycarbonate can be appropriately set depending on the purpose, etc., and is preferably designed in consideration of the type and thickness of the card to be used.

(Other ingredients)
In addition to the main components, the base sheet may contain stabilizers, lubricants, impact modifiers, colorants, antioxidants, hydrolysis inhibitors, fillers, ultraviolet absorbers, antiblocking agents, and antistatic agents, if necessary. Inhibitors, processing aids, and the like may be contained within the range that does not impair the effects of the present invention.

(Thickness of base sheet)
The thickness of the base sheet is preferably within the range of 0.03 to 0.25 mm.
It is preferable that the thickness of the base sheet is 0.03 mm or more because it is effective in protecting the printed surface of the core sheet. Further, it is preferable that the thickness of the base sheet is 0.25 mm or less because light transmittance is maintained and visibility of fine patterns, lines, characters, etc. on the printed surface of the core sheet can be ensured.
From this viewpoint, the thickness of the base sheet is preferably within the range of 0.03 to 0.25 mm, and more preferably 0.05 mm or more or 0.12 mm or less.

(Features of base sheet)
The base sheet constituting the card oversheet is preferably transparent. If the base sheet is transparent, when the oversheet for this card is laminated on the printing layer of the core sheet, visibility of fine patterns, lines, characters, etc. on the surface of the printing layer can be ensured. .
In the present invention, "transparent" means that the total light transmittance of a 0.10 mm thick sheet is 80% or more. The total light transmittance is a value measured based on JIS K7105.

(Method for forming base sheet)
A method for forming a base sheet, in particular a method for producing a sheet whose main resin is one selected from the group consisting of hard vinyl chloride, polyester resin, polycarbonate, and a polymer alloy of polyester resin and polycarbonate. For example, it can be formed by calendering, extrusion molding, or the like.

<Heat-sensitive adhesive layer>
The heat-sensitive adhesive layer in this card oversheet is mainly composed of one of polyurethane resins and polyamide resins, or an adhesive resin containing these two resins as main component resins, and a carbodiimide compound. Preferably, it is a layer. That is, it is preferably formed from a composition containing the adhesive resin and a carbodiimide compound as main components.

Here, the "main component resin" refers to 50% by mass or more, preferably 75% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass of the resin components constituting the adhesive resin. % or more, particularly preferably 95% by mass or more (the upper limit is 100% by mass).
Further, the "main component" refers to 50% by mass or more, preferably 75% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, especially This means that the adhesive resin and the carbodiimide compound preferably account for 95% by mass or more (the upper limit is 100% by mass).

(Polyamide resin)
The polyamide resin is preferably a polyamide resin produced by condensation polymerization of dimer acid and diamine, and among them, an amine value of 6 to 11, an acid value of 2 or less, and a softening point measured by the ring and ball method of 130°C or higher. Particularly preferred are those.
Examples of such polyamide resins include reaction products of dimer acids, such as oleic acid and linolenic acid, and diamines. Specifically, the product name "Technomelt" manufactured by Henkel Japan Co., Ltd. and the product name "Vejichem Green" manufactured by Tsukino Foods Co., Ltd. are commercially available.

(Polyurethane resin)
The polyurethane resin is not particularly limited, and examples include polyether polyurethane resin, polyester polyurethane resin, and polycarbonate polyurethane resin, and preferably polyester polyurethane resin and polycarbonate polyurethane resin. .
Polyurethane resins are generally manufactured by subjecting polyols, isocyanates, chain extenders, etc. to a urethane reaction in a solvent, and consist of a soft sea phase consisting of a polyol component with weak cohesive force and a strong cohesive force. It forms a sea-island structure consisting of hard island phases composed of urethane and urea bonds. Therefore, by using different polyol components, the properties of the polyurethane resin can be controlled.

For example, a polyester-based polyurethane resin using a polyester polyol is preferable because it has excellent heat resistance.
Further, a polycarbonate-based polyurethane resin using a polycarbonate polyol is preferable because it has excellent water resistance and weather resistance in addition to heat resistance.
Therefore, the polyurethane resin is preferably a polycarbonate polyurethane resin, a polyester polyurethane resin, or a mixed resin of both.

When the adhesive resin contains a polyurethane resin and a polyamide resin, the content ratio (parts by mass) of both is preferably 9:1 to 1:9, particularly 7:3 to 3:7, and preferably 7:3 to 3:7. Among them, a ratio of 6:4 to 3:7 is more preferable.

(Carbodiimide compound)
A carbodiimide compound is a compound having one or more carbodiimide groups in its molecule, and polycarbodiimide compounds are also included in this definition. Carbodiimide compounds generally include aliphatic carbodiimide compounds and aromatic carbodiimide compounds, and among them, it is preferable to use aliphatic carbodiimide compounds in the present invention.
Since aliphatic carbodiimide compounds have higher reactivity than aromatic carbodiimide compounds, they are more effective in inhibiting hydrolysis of adhesive resin compositions containing them, and the durability of the heat-sensitive adhesive layer is improved. preferable.

Preferred examples of carbodiimide compounds include those having the basic structure shown in the following general formula.
-(N=C=NR-) _n -
In the formula, n represents an integer of 1 or more, and R represents an organic bonding unit. For example, R can be either aliphatic or alicyclic. Further, n is usually selected as an appropriate integer between 1 and 50. When n is 2 or more, two or more R's may be the same or different.

Specific examples of the carbodiimide compound include poly(tolylcarbodiimide), poly(hexamethylenecarbodiimide), and monomers thereof. These carbodiimide compounds may be used alone or in combination of two or more. Further, for example, as an aliphatic carbodiimide compound, the trade name "Carbodilite" manufactured by Nisshinbo Chemical Co., Ltd. can be obtained commercially.

The carbodiimide compound can be controlled to an appropriate degree of polymerization by stopping the polymerization reaction midway through cooling or the like, and in this case, the terminal becomes isocyanate. By controlling the degree of polymerization, compatibility with adhesive resins or storage stability can be improved.

The carbodiimide compound may be a carbodiimide compound having an isocyanate group at the end (hereinafter referred to as "carbodiimide-modified isocyanate"). As such a carbodiimide-modified isocyanate, for example, the trade name "Carbodilite" manufactured by Nisshinbo Chemical Co., Ltd. can be obtained commercially.

The carbodiimide compound is preferably contained in an amount of 0.3 to 7 parts by weight based on 100 parts by weight of the adhesive resin, preferably 1 part by weight or more, and preferably 3 parts by weight or more or 5 parts by weight or less. preferable.
It is preferable that the content of the carbodiimide compound is 0.3 parts by mass or more because the effect of inhibiting hydrolysis of the adhesive resin composition can be obtained. In addition, if the content of the carbodiimide compound is 7 parts by mass or less, rapid reactions within the adhesive resin composition are suppressed, and for example, when the adhesive resin composition is dissolved in a solvent to form a coating liquid, This is preferable because thickening of the solution or shortening of the pot life period can be suppressed.

(Inorganic filler)
The heat-sensitive adhesive layer may contain an inorganic filler as a component other than the adhesive resin and carbodiimide compound.

The inorganic filler contained in the heat-sensitive adhesive layer preferably has an average particle size of 0.2 μm to 6 μm, and preferably contains an inorganic filler with an average particle size of 1 μm or more or 4 μm or less. preferable.
If the average particle size is 0.2 μm or more, it is preferable because, for example, when an adhesive is dissolved in a solvent to form a coating liquid, it can be uniformly dispersed. Further, it is preferable that the average particle diameter is 6 μm or less, since the transparency of the heat-sensitive adhesive layer is ensured.
Here, the average particle size can be determined as the average value of, for example, 10 or more particles observed with a scanning electron microscope (SEM) and the diameters of the particles measured. In the case of non-spherical particles, the diameter of each particle is the average value of the longest diameter and the shortest diameter. However, for the average particle diameter of the inorganic filler as a raw material, D50 based on a volume-based particle size distribution obtained by measurement by a laser diffraction scattering particle size distribution measurement method can be adopted.

When the heat-sensitive adhesive layer contains such an inorganic filler, the bonding strength, hardness, etc. of the adhesive can be increased. That is, it is possible to increase the adhesive strength between each layer of the card formed by heat-fusion bonding. Further, when the rolled card oversheet is rewound or stacked into sheets, it is possible to prevent the sheets from coming into close contact with each other, so-called blocking.

Such inorganic fillers are not particularly limited, and include, for example, silica, calcium carbonate, barium sulfate, talc, clay, etc., and any one or two or more of these may be mixed. I can list some things that I did. Among these, silica, calcium carbonate, and talc are preferred.

The content of the inorganic filler is preferably 1 to 20 parts by mass based on the total of 100 parts by mass of the adhesive resin and the carbodiimide compound, and preferably 3 parts by mass or more or 15 parts by mass or less. is preferable.
If the content of the inorganic filler is 1 part by mass or more, the above effects can be sufficiently obtained, and if the content of the inorganic filler is 20 parts by mass or less, there will be a decrease in adhesiveness and mechanical strength. No deterioration occurs and the oversheet is not colored.

(Other ingredients)
The heat-sensitive adhesive layer contains, in addition to the adhesive resin, carbodiimide compound, and inorganic filler, a stabilizer, a lubricant, an impact modifier, a coloring agent, an antioxidant, an ultraviolet absorber, and an antistatic agent, if necessary. , processing aids, etc. may be contained within a range that does not impair the effects of the present invention.

(Method for forming heat-sensitive adhesive layer)
The method for forming the heat-sensitive adhesive layer is, for example, by dissolving the adhesive resin in a solvent, adding a carbodiimide compound and stirring to form a uniform coating solution, and coating it on one side of the base sheet using a bar coater or roll coater. It can be formed by coating and drying using various coaters such as , blade coater, and gravure coater. In the present invention, it is preferable to use a gravure coater because a thinner heat-sensitive adhesive layer can be uniformly formed.
At this time, the solvent used is not particularly limited. For example, it is preferable to use a mixture of toluene, ethyl acetate, methyl ethyl ketone (MEK), isopropyl alcohol, ethanol, water, and the like.
The coating liquid preferably has a solid content of 10 to 40% by mass of the adhesive resin composition, etc., and a viscosity of 100 to 1,000 cps, and by using a coating liquid adjusted in this way, uniformity can be achieved. A thin heat-sensitive adhesive layer can be formed.

(Method for forming heat-sensitive adhesive layer)
The thickness of the heat-sensitive adhesive layer (after drying) is preferably 1 to 10 μm, particularly preferably 3 μm or more or 7 μm or less. It is preferable that the thickness of the heat-sensitive adhesive layer (after drying) is 1 μm or more, since this ensures good adhesion to the ink forming the printed surface of the core sheet.
At this time, if the thickness of the heat-sensitive adhesive layer (after drying) is 10 μm or less, the light transmittance of the heat-sensitive adhesive layer is maintained, allowing fine patterns, lines, and characters on the printed surface of the core sheet to be This is preferable because visibility such as the following can be ensured.

(Storage modulus of adhesive resin)
The adhesive resin preferably has a storage modulus of 1×10 ⁷ Pa or more at 50°C. If the storage elastic modulus is 1×10 ⁷ Pa or more, tackiness of the heat-sensitive adhesive layer of the card oversheet is suppressed, and it is possible to unwind the sheet wound into a roll or stack the sheets into sheets. This is preferable because it can ensure handling properties such as.
From this viewpoint, the storage modulus at 50° C. is more preferably 1.5×10 ⁷ Pa or more, even more preferably 1.8×10 ⁷ Pa or more, and 30×10 ⁷ Pa or less. is preferable, more preferably 20×10 ⁷ Pa or less, and even more preferably 12×10 ⁷ Pa or less.

＜＜This card＞＞
Cards can be made using this card oversheet.
A card according to an embodiment of the present invention (referred to as "this card") has a printed layer laminated on at least one surface of a core sheet constituting the card, and at least the surface of the printed layer, that is, the opposite side of the core sheet. One example is a card having a structure in which a main card oversheet is laminated on the side surface.

This card is made by, for example, printing an image or the like on at least one side of a white core sheet by silk screen printing and/or offset printing to form a printing layer, and an overlay for this card on the surface of this printing layer. The sheet can be formed by temporarily pasting the sheets one on top of the other so that their heat-sensitive adhesive layers are in contact with each other, and then sandwiching the sheets between decorative boards or the like and bonding them by thermocompression.

In this case, the ink used for the above printing is an ultraviolet curable ink whose main component is epoxy acrylate, polyester acrylate, polyurethane acrylate, etc., and if these inks are used for solid printing on the entire surface of the core sheet. However, the heat-sensitive adhesive layer of the oversheet for this card has sufficient adhesion to the printed layer, and has excellent durability, such as excellent durability even under the above-mentioned high temperature and high humidity atmosphere. can demonstrate.

The card may have a structure in which a core sheet has a printed layer such as an image on one side, and an oversheet for the card is laminated thereon, or an oversheet for the card may be laminated on the other side that is not printed. It is also possible to have a structure in which these are laminated.
Alternatively, the core sheet may have a printed layer such as an image on both sides, and the printed layer surfaces on both sides may be covered with an oversheet for the main card.

Note that a card can also be produced by forming a magnetic stripe tape or the like on the oversheet for the card and then bonding it to the core sheet.
Generally, a card is formed by bonding a card oversheet and a core sheet under heat and then punching them into a card shape using a punching machine.

Next, the configuration of an example of this card will be specifically explained using the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of the configuration of this card. Printed layers 2 are formed on both sides of the core sheet 1 by printing images and the like by silk screen printing and/or offset printing.
On the surface of the printing layer 2, a card oversheet 3 is bonded by thermocompression. Note that the card oversheet 3 is composed of an adhesive layer 4 and a base sheet 5.

EXAMPLES The present invention will be explained in more detail with reference to Examples below. However, the present invention is not limited to these, and various applications are possible without departing from the technical idea of the present invention.

<Measurement and evaluation method>
A method for measuring and evaluating various physical property values of samples obtained in Examples and Comparative Examples will be explained.

[Adhesive strength]
The heat-sensitive adhesive layer and the printing layer of the test piece (peel width 10 mm) were separated by about 30 mm in advance, and the card oversheet and core sheet were respectively attached to the grip of the testing machine and tested according to JIS K6854-3. A T-peel test was conducted to determine the adhesive strength. Note that the peel test speed was 300 mm/min.

[Durability 1]
A T-peel test was performed on the test piece (peel width 10 mm) stored for 250 hours in a constant temperature and humidity chamber adjusted to a 75°C x 90% RH atmosphere (exposure condition 1) using the same procedure as the adhesive strength evaluation method described above. The adhesive strength (N/10mm) was determined. Durability 1 of the obtained adhesive strength was evaluated based on the following criteria.

(Judgment criteria)
○: 6 (N/10mm) ≦Measured adhesive strength △: 3 (N/10mm) ≦Measured adhesive strength <6 (N/10mm)
×: Measured adhesive strength <3 (N/10mm)

[Durability 2]
The above adhesive strength evaluation method for test pieces (peel width 10 mm) stored for 0 weeks (before exposure), 1 week, and 2 weeks in a constant temperature and humidity chamber adjusted to a 75 ° C x 95% RH atmosphere (exposure condition 2) A T-peel test was conducted in the same manner as above, and the peeling state was observed and the adhesive strength (N/10 mm) was measured.
Regarding the results obtained before exposure, after exposure for 1 week, and after exposure for 2 weeks, the peeling state and adhesive strength were evaluated based on the following criteria.

(Judgment criteria)
○: Cohesive failure occurred within the core sheet. Or, measured adhesive strength ≧1 (N/10mm)
×: Measured adhesive strength <1 (N/10mm)

Furthermore, durability 2 was evaluated based on the following criteria.
(Judgment criteria)
○: The evaluation results of the peeling state and adhesive strength of the test pieces stored for 1 week and 2 weeks were "○".
△: Only the test piece stored for one week had an evaluation result of "○" for peeling state and adhesive strength.
×: The evaluation result of the adhesive strength of the test piece stored for one week was “×”.

[Anti-discoloration property]
Based on JIS K7105, the YI was measured from the oversheet side using the following equipment for the test piece stored for 500 hours in a constant temperature and humidity chamber adjusted to a 75°C x 90% RH atmosphere (exposure condition 1), and the YI was measured before and after exposure. The amount of change in YI was calculated and set as ΔYI.
ΔYI = | YI before storage - YI after storage |

Measuring device: Spectrophotometer “SC-T type” (manufactured by Suga Test Instruments Co., Ltd.)
Measurement mode: Reflection Measurement hole: Diameter 30mm
Optical conditions: JIS Z8722 condition C (8 degree light reception, d/8 method)
Light source: C (2 degree field of view)
Regarding the obtained amount of change, the discoloration prevention property was evaluated based on the following criteria.

(Judgment criteria)
○: ΔYI≦0.5, and the discoloration prevention property was particularly excellent.
Δ: 0.5<ΔYI≦0.9, and the discoloration prevention property was excellent.
×: 0.9<ΔYI, and the anti-discoloration property was poor.

[Anti-blocking property]
Two A5 size card oversheets were stacked in the following order: base sheet/thermal adhesive layer/base sheet/thermal adhesive layer, and a 5 kg weight was placed on top of them.
After storing the card oversheet with a weight on it for two weeks in a constant temperature and humidity chamber adjusted to an atmosphere of 50°C and 50% RH, the resistance and appearance of the oversheet when peeled off from each other were measured. It was confirmed.
The results were evaluated for anti-blocking properties based on the following criteria.

(Judgment criteria)
○: The resistance force when peeling off the sheet was light, and there was no transfer of the heat-sensitive adhesive layer to the base sheet side.
×: The resistance when peeling the sheet was strong, and there was transfer of the heat-sensitive adhesive layer to the base sheet side.

[Storage modulus]
For the adhesive resins used in Examples and Comparative Examples, dynamic viscoelasticity was measured according to the JIS K7198A method using the following apparatus, and the storage modulus at 50°C was read.
Equipment: Dynamic viscoelasticity measuring device DVA-200 (manufactured by IT Keizai Control Co., Ltd.)
Measurement method: Tensile method Distance between chucks: 25mm
Distortion: 0.1%
Temperature range: -50℃~200℃
Temperature increase rate: 3℃/min
Frequency: 1Hz
The measurement sample was prepared by drying and volatilizing the solvent in which each adhesive resin was dissolved and forming a sheet with a thickness of about 1 mm.

<Example 1>
An adhesive coating solution (A) was prepared as described next, and using this adhesive coating solution (A), a card oversheet (A) was produced as explained next. Then, using this card oversheet (A), a card sheet (A-1), a card sheet (A-2), and a test sheet (A-3) were produced as described below. , the card oversheet (A) was evaluated for blocking prevention, the card sheet (A-1) was evaluated for adhesive strength and durability 1, and the card sheet (A-2) was evaluated for durability 2. The test sheet (A-3) was evaluated for discoloration prevention properties.

(Preparation of adhesive coating liquid (A))
A polyamide resin (manufactured by Henkel Japan Co., Ltd., trade name "Technomelt PA6823", storage modulus (50°C) 2 x 10 ⁷ Pa) was used as an adhesive resin, and a solvent (toluene and isopropyl alcohol in a mass ratio of 50:50) was used. After dissolving in the mixed solution (mixed liquid mixed in ), the solid content of carbodiimide compound A (manufactured by Nisshinbo Chemical Co., Ltd., trade name "Carbodilite V-07") will be 5 parts by mass with respect to 100 parts by mass of the polyamide resin. The adhesive coating liquid (A) was obtained by mixing as follows. Here, the solid content of the adhesive coating liquid (A) was 15% by mass.

(Preparation of card oversheet (A))
The above coating solution ( A) was applied and dried at 100° C. for 5 minutes to obtain a transparent card oversheet (A) consisting of a heat-sensitive adhesive layer/base sheet.
The obtained card oversheet (A) was evaluated for anti-blocking properties.

(Preparation of card sheet (A-1))
Next, on one side of a core sheet made of polyvinyl chloride with a thickness of 0.15 mm, a printed layer (thickness: 2 μm) was printed on the entire surface by offset printing using a polyester acrylate ink as an ultraviolet curable ink. The above-mentioned card oversheet (A) was placed on the surface of this printing layer with the heat-sensitive adhesive layer on the inside, and then placed in a heat press machine and heated at a temperature of 140°C and a pressure of 10 kgf/cm ² . After thermocompression bonding is performed for 30 minutes under pressure, it is cooled to room temperature and the composition of card oversheet (A)/printing layer/core sheet is formed, that is, base sheet/thermosensitive adhesive layer/printing layer/core sheet. A card sheet (A-1) with the following configuration was prepared.
The obtained card sheet (A-1) was evaluated for adhesive strength and durability 1.

(Preparation of card sheet (A-2))
On the other hand, a printed layer ( The card oversheet (A) was placed on top of this printing layer with the heat-sensitive adhesive layer on the inside, and then placed in a heat press and pressed at a temperature of 140°C and a weight of 10 kgf. / ^cm2 for 20 minutes, then cooled to room temperature to form a card oversheet (A)/printing layer/core sheet, that is, base sheet/thermosensitive adhesive layer/printing layer. A card sheet (A-2) having a structure of /core sheet was produced.
The obtained card sheet (A-2) was evaluated for durability 2.

(Preparation of test sheet (A-3))
In order to evaluate the discoloration prevention property of the heat-sensitive adhesive layer, a core sheet made of copolymerized polyester with a thickness of 0.13 mm (manufactured by Mitsubishi Chemical Corporation, PG-WTS-HM) without printing, and a core sheet for the above-mentioned card were prepared. The oversheet (A) and the oversheet (A) were placed in a heat press machine and thermocompression bonded at a temperature of 140°C and a pressure of 10 kgf/cm ² for 20 minutes, and then cooled to room temperature to form a card oversheet (A)/core sheet. A test sheet (A-3) having the following configuration, that is, the configuration of base sheet/heat-sensitive adhesive layer/core sheet was produced.
The obtained test sheet (A-3) was evaluated for discoloration prevention properties.

<Example 2>
An adhesive coating solution (B) was prepared as described next, and using this adhesive coating solution (B), a card oversheet (B) was produced as described below. Then, using this card oversheet (B), a card sheet (B-1), a card sheet (B-2), and a test sheet (B-3) were made as described below. In the same manner as in Example 1, anti-blocking properties, adhesive strength, durability 1, durability 2, and anti-discoloration properties were evaluated.

(Preparation of adhesive coating liquid (B))
In preparing the adhesive coating liquid (A) of Example 1, in addition to mixing 5 parts by mass of carbodiimide compound A in solid content with 100 parts by mass of polyamide resin, silica (manufactured by Fuji Silicia Chemical Co., Ltd., Adhesive coating liquid (B) was obtained in the same manner as adhesive coating liquid (A), except that 3 parts by mass of product name "Silohobic 702" (average particle size (D50) 4 μm) were mixed. . At this time, the solid content of the adhesive coating liquid (B) was 15% by mass.

(Preparation of card oversheet (B))
The card sheet of Example 1, except that the adhesive coating liquid (B) was used instead of the adhesive coating liquid (A) in producing the card oversheet (A) of Example 1. An oversheet for cards (B) was obtained in the same manner as in (A).
The obtained card oversheet (B) was evaluated for anti-blocking properties.

(Preparation of card sheet (B-1))
The card sheet (A-1) of Example 1 was prepared using the card sheet (A-1) of Example 1, except that the card over sheet (B) was used instead of the card over sheet (A). In the same manner as A-1), a card sheet (B- 1) was produced.
The obtained card sheet (B-1) was evaluated for adhesive strength and durability 1.

(Preparation of card sheet (B-2))
The card sheet (A-2) of Example 1 was prepared using the card sheet (A-2) of Example 1, except that the card over sheet (B) was used instead of the card over sheet (A). In the same manner as A-2), a card sheet (B- 2) was produced.
The obtained card sheet (B-2) was evaluated for durability 2.

(Preparation of test sheet (B-3))
The test sheet (A-3) of Example 1 was prepared using the test sheet (A-3) of Example 1, except that the card oversheet (B) was used instead of the card oversheet (A). In the same manner as A-3), a test sheet (B-3) having a card oversheet (B)/core sheet configuration, that is, a base sheet/thermal adhesive layer/core sheet configuration was produced.
The obtained test sheet (B-3) was evaluated for discoloration prevention properties.

<Example 3>
An adhesive coating solution (C) was prepared as described next, and using this adhesive coating solution (C), a card oversheet (C) was produced as explained next. Then, using this card oversheet (C), a card sheet (C-1), a card sheet (C-2), and a test sheet (C-3) were made as described below. In the same manner as in Example 1, anti-blocking properties, adhesive strength, durability 1, durability 2, and anti-discoloration properties were evaluated.

(Preparation of adhesive coating liquid (C))
A polyester polyurethane resin (manufactured by Sanyo Kasei Kogyo Co., Ltd., trade name "Samplen IB-465", storage modulus (50°C) 9 x 10 ⁷ Pa) was used as the adhesive resin, and a solvent (ethyl acetate and isopropyl alcohol in mass ratio) was used. After dissolving the carbodiimide compound A (manufactured by Nisshinbo Chemical Co., Ltd., trade name "Carbodilite V-07") in a solid content of 5 parts by mass of polyester polyurethane resin (mixed liquid mixed at a ratio of 50:50), The adhesive coating liquid (C) was obtained by mixing the parts by mass. Here, the solid content of the adhesive coating liquid (C) was 15% by mass.

(Preparation of card oversheet (C))
The card oversheet of Example 1 except that the adhesive coating liquid (C) was used instead of the adhesive coating liquid (A) in the production of the card oversheet (A) of Example 1. An oversheet for cards (C) was obtained in the same manner as the sheet (A).
The obtained card oversheet (C) was evaluated for anti-blocking properties.

(Preparation of card sheet (C-1))
The card sheet (A-1) of Example 1 was prepared using the card sheet (A-1) of Example 1, except that the card over sheet (C) was used instead of the card over sheet (A). In the same manner as A-1), a card sheet (C- 1) was produced.
The obtained card sheet (C-1) was evaluated for adhesive strength and durability 1.

(Preparation of card sheet (C-2))
The card sheet (A-2) of Example 1 was prepared using the card sheet (A-2) of Example 1, except that the card over sheet (C) was used instead of the card over sheet (A). -2), a card sheet (C-2) having the structure of card oversheet (C)/printing layer/core sheet, that is, the structure of base sheet/thermal adhesive layer/printing layer/core sheet ) was created.
The obtained card sheet (C-2) was evaluated for durability 2.

(Preparation of test sheet (C-3))
The test sheet (A-3) of Example 1 was prepared using the test sheet (A-3) of Example 1, except that the card oversheet (C) was used instead of the card oversheet (A). In the same manner as A-3), a test sheet (C-3) having a card oversheet (C)/core sheet configuration, that is, a base sheet/thermal adhesive layer/core sheet configuration was produced.
The obtained test sheet (C-3) was evaluated for discoloration prevention properties.

<Example 4>
An adhesive coating solution (D) was prepared as described next, and using this adhesive coating solution (D), a card oversheet (D) was produced as explained next. Then, using this card oversheet (D), a card sheet (D-1), a card sheet (D-2), and a test sheet (D-3) were made as described below. In the same manner as in Example 1, anti-blocking properties, adhesive strength, durability 1, durability 2, and anti-discoloration properties were evaluated.

(Preparation of adhesive coating liquid (D))
Polycarbonate-based polyurethane resin (manufactured by Sanyo Kasei Kogyo Co., Ltd., trade name "Ucoat UX-320", storage modulus (50°C) 3×10 ⁷ Pa) was dissolved as an adhesive resin in water, and then the polycarbonate-based polyurethane resin An adhesive coating liquid (D) was obtained by mixing 5 parts by mass of carbodiimide compound B (manufactured by Nisshinbo Chemical Co., Ltd., trade name "Carbodilite E-05") to 100 parts by mass. Here, the solid content of the adhesive coating liquid (D) was 15% by mass.

(Preparation of card oversheet (D))
The card oversheet of Example 1 except that the adhesive coating liquid (D) was used instead of the adhesive coating liquid (A) in the production of the card oversheet (A) of Example 1. An oversheet for cards (D) was obtained in the same manner as the sheet (A).
The obtained card oversheet (D) was evaluated for anti-blocking properties.

(Production of card sheet (D-1) In the production of card sheet (A-1) in Example 1, the above-mentioned card oversheet (D) was used instead of card oversheet (A). Except for this, the structure was the same as that of the card sheet (A-1) of Example 1, except that the card oversheet (D)/printing layer/core sheet, that is, the base sheet/thermal adhesive layer/printing layer/ A card sheet (D-1) having a structure called a core sheet was produced.
The obtained card sheet (D-1) was evaluated for adhesive strength and durability 1.

(Preparation of card sheet (D-2))
The card sheet (A-2) of Example 1 was prepared using the card sheet (A-2) of Example 1, except that the card over sheet (D) was used instead of the card over sheet (A). -2), a card sheet (D-2) having the structure of card oversheet (D)/printing layer/core sheet, that is, the structure of base sheet/thermal adhesive layer/printing layer/core sheet ) was created.
The obtained card sheet (D-2) was evaluated for durability 2.

(Preparation of test sheet (D-3))
The test sheet (A-3) of Example 1 was prepared using the test sheet (A-3) of Example 1, except that the card oversheet (D) was used instead of the card oversheet (A). In the same manner as A-3), a test sheet (D-3) having a card oversheet (D)/core sheet configuration, that is, a base sheet/thermal adhesive layer/core sheet configuration was produced.
The obtained test sheet (D-3) was evaluated for discoloration prevention properties.

<Comparative example 1>
An adhesive coating solution (E) was prepared as described next, and using this adhesive coating solution (E), a card oversheet (E) was produced as described next. Then, using this card oversheet (E), a card sheet (E-1) and a test sheet (E-3) were prepared as described below, and the card oversheet (E) was Anti-blocking properties were evaluated, adhesive strength and durability 1 were evaluated for the card sheet (E-1), and discoloration prevention properties were evaluated for the test sheet (E-3).

(Preparation of adhesive coating liquid (E))
Adhesive coating was performed in the same manner as the adhesive coating solution (A) of Example 1, except that carbodiimide compound A was not blended in the preparation of the adhesive coating solution (A) of Example 1. Liquid (E) was obtained. Here, the solid content of the adhesive coating liquid (E) was 15% by mass.

(Preparation of card oversheet (E))
The card oversheet of Example 1 except that the adhesive coating liquid (E) was used instead of the adhesive coating liquid (A) in the production of the card oversheet (A) of Example 1. An oversheet for cards (E) was obtained in the same manner as the sheet (A).
The obtained card oversheet (E) was evaluated for anti-blocking properties.

(Preparation of card sheet (E-1))
The card sheet (A-1) of Example 1 was prepared using the card sheet (A-1) of Example 1, except that the card over sheet (E) was used instead of the card over sheet (A). In the same manner as A-1), a card sheet (E- 1) was produced.
The obtained card sheet (E-1) was evaluated for adhesive strength and durability 1.

(Preparation of test sheet (E-3))
The test sheet (A-3) of Example 1 was prepared using the test sheet (A-3) of Example 1, except that the card oversheet (E) was used instead of the card oversheet (A). In the same manner as in -3), a test sheet (E-3) having a card oversheet (E)/core sheet configuration, that is, a base sheet/thermal adhesive layer/core sheet configuration was produced.
The obtained test sheet (E-3) was evaluated for discoloration prevention properties.

<Comparative example 2>
An adhesive coating solution (F) was prepared as described next, and using this adhesive coating solution (F), a card oversheet (F) was produced as described below. Using this card oversheet (F), a card sheet (F-1) was prepared as described below, and the card oversheet (F) was evaluated for blocking prevention. The adhesive strength and durability 1 of the sheet (F-1) were evaluated.

(Preparation of adhesive coating liquid (F))
A polyester resin (manufactured by Toagosei Co., Ltd., trade name "Aronmelt PES", storage modulus (50°C) 2×10 ⁶ Pa) was dissolved as an adhesive resin in a solvent (ethyl acetate), and then the polyester resin 100 In addition to mixing 5 parts by mass of carbodiimide compound A as a solid content, 3 parts by mass of silica (manufactured by Fuji Silysia Chemical Co., Ltd., trade name "Silohobic 702", average particle size (D50) 4 μm) were mixed to obtain an adhesive coating liquid (F). At this time, the solid content of the adhesive coating liquid (F) was 15% by mass.

(Preparation of card oversheet (F))
The card oversheet of Example 1 except that the adhesive coating liquid (F) was used instead of the adhesive coating liquid (A) in the production of the card oversheet (A) of Example 1. An oversheet for cards (F) was obtained in the same manner as the sheet (A).
The obtained card oversheet (F) was evaluated for anti-blocking properties.

(Preparation of card sheet (F-1))
In the production of the card sheet (A-1) in Example 1, the card oversheet (F) was used instead of the card oversheet (A), and the card sheet (F) was placed in a heat press machine and thermocompression bonded for 10 minutes. The structure of the card oversheet (F)/printing layer/core sheet, that is, the base sheet/thermal adhesive layer was prepared in the same manner as the card sheet (A-1) of Example 1, except that A card sheet (F-1) having the following structure was produced: /printing layer/core sheet.
The obtained card sheet (F-1) was evaluated for adhesive strength and durability 1.

The obtained evaluation results are shown in Table 1.

(Consideration)
From Table 1, it can be seen that the card oversheets and card sheets of Examples 1 to 4 were thermosensitive resins containing a combination of an adhesive resin containing a polyurethane resin and/or a polyamide resin, and a carbodiimide compound as a main component. It was found that by using the mold adhesive layer, discoloration was suppressed and adhesive strength was maintained well in evaluations of discoloration prevention properties and durability.
On the other hand, in the card oversheet of Comparative Example 1, when a heat-sensitive adhesive layer containing no carbodiimide compound was used, it was found that the durability and discoloration prevention properties were inferior in evaluation. In addition, in the card sheet of Comparative Example 2, even if a heat-sensitive adhesive layer containing an adhesive resin made of polyester resin and a carbodiimide compound as the main components was used, the adhesive strength was lowered in the durability evaluation. I understand.

1 Core sheet 2 Printing layer 3 Card oversheet 4 Heat-sensitive adhesive layer 5 Base sheet

Claims (11)

It has a structure in which a heat-sensitive adhesive layer is provided on one side of the base sheet,
The heat-sensitive adhesive layer is a heat-sensitive adhesive layer obtained by coating and drying a solvent-based coating liquid containing an adhesive resin containing a polyurethane resin and/or a polyamide resin, and a carbodiimide compound as main components. Features an oversheet for cards. It has a structure in which a heat-sensitive adhesive layer is provided on one side of the base sheet,
1. An oversheet for a card, wherein the heat-sensitive adhesive layer contains as main components an adhesive resin containing a polyester-based polyurethane resin or a polycarbonate-based polyurethane resin, and a carbodiimide compound. It has a structure in which a heat-sensitive adhesive layer is provided on one side of the base sheet,
An oversheet for a card, wherein the heat-sensitive adhesive layer contains as main components an adhesive resin containing a polyamide resin and a carbodiimide compound. It has a structure in which a heat-sensitive adhesive layer is provided on one side of the base sheet,
The heat-sensitive adhesive layer mainly contains an adhesive resin containing a polyurethane resin and/or a polyamide resin, and a carbodiimide compound ,
An oversheet for cards, wherein the base sheet is a sheet whose main component is one resin selected from the group consisting of polyester resin, polycarbonate, and a polymer alloy of polyester resin and polycarbonate. 5. The card oversheet according to claim 1 , wherein the polyamide resin is a polyamide resin obtained by condensation polymerization of dimer acid and diamine. The card oversheet according to any one of claims 1 to 5 , wherein the carbodiimide compound includes an aliphatic carbodiimide compound. The card oversheet according to any one of claims 1 to 5 , wherein the carbodiimide compound is an aliphatic carbodiimide compound. The card oversheet according to any one of claims 1 to 7 , wherein the carbodiimide compound is contained in an amount of 0.3 to 7 parts by mass based on 100 parts by mass of the adhesive resin. The heat-sensitive adhesive layer is characterized in that it contains 1 to 20 parts by mass of an inorganic filler with an average particle size of 0.2 to 6 μm based on a total of 100 parts by mass of the adhesive resin and the carbodiimide compound. The card oversheet according to any one of claims 1 to 8 . A printed layer is laminated on at least one surface of a core sheet constituting a card, and the card oversheet according to any one of claims 1 to 9 is laminated on at least the surface of the printed layer. card. An adhesive resin containing a polyurethane resin and/or a polyamide resin is dissolved in a solvent and a carbodiimide compound is added thereto to obtain a coating solution.The coating solution is applied to one side of the base sheet and dried to form a heat-sensitive adhesive layer. 1. A method for producing a card oversheet, the method comprising: providing a card oversheet.

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