JP2006095842A - Thermal recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal recording body having an adhesive layer which can reduce protrusion of an adhesive component from the lateral side of a roll and can suppress an increase with time of a force of release of the adhesive layer from a release layer. <P>SOLUTION: The thermal recording body has a base, a thermal recording layer formed on one surface of the base, the release layer formed on the thermal recording layer and the adhesive layer formed on the other surface of the base. The loss tangent tanδ of the adhesive layer at 150°C is 0.05-0.2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat-sensitive recording material having a pressure-sensitive adhesive layer, and a so-called separate-type heat-sensitive recording material having no separator.

  Thermal recording media that react with a heat-sensitive dye and a colorant by heat to obtain desired characters and the like are widely known. Such thermal recording media are relatively inexpensive, so that such as facsimiles and various computers. Used for recording media. Further, as a usage specification used in ATMs such as banks, a heat-sensitive recording material having a very thin film thickness is used.

  Furthermore, by providing a pressure-sensitive adhesive layer on one side of the base material of the heat-sensitive recording material, a heat-sensitive recording material that can be attached can be obtained. Examples of such a heat-sensitive recording material that can be attached include a so-called separate-type heat-sensitive recording material that does not have a separator. A separate-type heat-sensitive recording material is usually wound into a roll with the pressure-sensitive adhesive layer inside, and the release layer and the pressure-sensitive adhesive layer are in contact with each other. Such a separate-type heat-sensitive recording material has an advantage that it can be made compact compared to a heat-sensitive recording material with a separator, and is used for food price tag stickers and the like. Further, such a separate-type thermal recording medium is disclosed in Patent Document 1, Patent Document 2, and Patent Document 3.

  However, the separate-type thermal recording material has a problem that the adhesive component may protrude from the side surface of the roll and the like, and the running property of the printer is deteriorated by adhering to peripheral devices. Furthermore, it is known that the peel force between the pressure-sensitive adhesive layer and the release layer increases with time, and this increase in peel force with time causes problems such as sticking.

JP 2004-001287 A JP 2003-228290 A JP 2003-228288 A

  The present invention has been made in view of the above-described problems, and can suppress the protrusion of the pressure-sensitive adhesive component from the roll side surface, and suppress the increase in peel strength with time between the pressure-sensitive adhesive layer and the release layer. The main object of the present invention is to provide a heat-sensitive recording material provided with a pressure-sensitive adhesive layer.

  The present invention is formed on a base material, a thermosensitive recording layer formed on one surface of the base material, a release layer formed on the thermosensitive recording layer, and the other surface of the base material. A heat-sensitive recording material comprising a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer has a loss tangent tan δ at 150 ° C. of 0.05 to 0.2.

  According to the present invention, since the loss tangent tan δ at 150 ° C. of the pressure-sensitive adhesive layer is in the above range, the pressure-sensitive adhesive component can be prevented from protruding from the side surface of the roll, and the pressure-sensitive adhesive component is added to the peripheral device. It is possible to suppress the adhesion and decrease in the running performance of the printer. Furthermore, an increase in peel force with time between the pressure-sensitive adhesive layer and the release layer can be suppressed, and sticking can be prevented.

  Moreover, in the said invention, it is preferable that the said adhesive layer contains an acrylic adhesive and a crosslinking agent. This is because the use of the above material can sufficiently exert the effect of suppressing the protrusion of the pressure-sensitive adhesive component and the increase in peel strength with time.

  Moreover, in the said invention, it is preferable that the film thickness of the said adhesive layer is 5-30 micrometers. This is because, if the thickness of the pressure-sensitive adhesive layer is within the above range, the effect of suppressing the protrusion of the pressure-sensitive adhesive component and the increase in peel strength with time can be sufficiently exerted.

Moreover, in the said invention, it is preferable that the solid content coating amount of the coating liquid for adhesive layer formation used in order to form the said adhesive layer is 5-30 g / m < ² >. This is because, if the solid content coating amount of the coating liquid for forming the pressure-sensitive adhesive layer is within the above range, it is possible to obtain a pressure-sensitive adhesive layer capable of suppressing the protrusion of the pressure-sensitive adhesive component and the increase in peel strength over time. .

  According to the present invention, by setting the loss tangent tan δ of the pressure-sensitive adhesive layer to an appropriate range, it is possible to suppress the protrusion of the pressure-sensitive adhesive component and to suppress the increase in the peel force with time of the pressure-sensitive adhesive layer and the release layer. It has the effect that it can be done.

  The present invention relates to a heat-sensitive recording material. The thermosensitive recording material of the present invention comprises a base material, a thermosensitive recording layer formed on one surface of the base material, a release layer formed on the thermosensitive recording layer, and the other surface of the base material. The pressure-sensitive adhesive layer has a loss tangent tan δ at 150 ° C. of 0.05 to 0.2. The heat-sensitive recording material of the present invention is usually wound up in a roll shape with the pressure-sensitive adhesive layer inside, and the release layer and the pressure-sensitive adhesive layer are in contact with each other.

  According to the present invention, by using the pressure-sensitive adhesive layer having a loss tangent tan δ at 150 ° C. in the above range, the pressure-sensitive adhesive component can be prevented from protruding from the side surface of the roll, and the pressure-sensitive adhesive component is a peripheral device. It is possible to suppress the deterioration of the running performance of the printer due to adhesion to the printer. Furthermore, an increase in peel force with time between the pressure-sensitive adhesive layer and the release layer can be suppressed, and sticking can be prevented.

Next, the thermal recording material of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the thermal recording material of the present invention. As shown in FIG. 1, the thermosensitive recording material of the present invention comprises a substrate 1, a thermosensitive recording layer 2 formed on one surface of the substrate 1, and a release formed on the thermosensitive recording layer 2. A layer 3 and a pressure-sensitive adhesive layer 4 formed on the other surface of the substrate 1 are provided.
Hereinafter, the pressure-sensitive adhesive layer, release layer, heat-sensitive recording layer, and substrate constituting such a heat-sensitive recording material will be described.

1. First, the pressure-sensitive adhesive layer used in the present invention will be described. The pressure-sensitive adhesive layer used in the present invention has a loss tangent tan δ at 150 ° C. of 0.05 to 0.2. By using the pressure-sensitive adhesive layer having the loss tangent tan δ within the above range, it is possible to suppress the pressure-sensitive adhesive component from protruding from the roll side surface and the increase in the time-dependent peeling force between the pressure-sensitive adhesive layer and the peeling layer.

  The loss tangent tan δ is a loss factor of energy loss when vibration strain is applied to the viscoelastic body. In the present invention, E obtained by DMA (dynamic viscoelasticity) measurement at 150 ° C. ′ (Storage elastic modulus) is a value given as tan δ = E ′ / E ″ using E ″ (loss elastic modulus). In the present invention, the loss tangent at 150 ° C. is set to a frequency of 1 Hz using a dynamic viscoelasticity device (manufactured by Rheometrics, Inc., solid viscoelasticity analyzer RSA-II) for the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. The dynamic viscoelasticity is measured under a measurement condition in which the temperature is raised from minus 50 ° C. to 200 ° C., and the dynamic viscoelasticity obtained by this measurement is read from a graph showing the temperature dependence.

(1) Film thickness of adhesive layer First, the film thickness of the adhesive layer used for this invention is demonstrated. The thickness of the pressure-sensitive adhesive layer used in the present invention is not particularly limited as long as it can form a pressure-sensitive adhesive layer having the above loss tangent tan δ within the above range, but specifically, 5 to 30 μm. It is preferable that it is 7-25 micrometers. If the thickness of the pressure-sensitive adhesive layer is 5 μm or less, the adhesive force may be reduced, and if it is 30 μm or more, the protruding diameter of the pressure-sensitive adhesive and the roll diameter increase despite the small number of rolls. This is because there is a possibility that problems such as these may occur. As the film thickness, a value measured by cross-sectional observation with an SEM (scanning electron microscope) is used.

Moreover, the solid content coating amount of the coating liquid for forming the adhesive layer is not particularly limited as long as the adhesive layer having the loss tangent tan δ within the above range can be formed. 30 g / ^{m 2,} is preferably Among them 7~25g / ^{m 2.} When the solid content coating amount of the pressure-sensitive adhesive layer forming coating solution is 5 g / m ² or less, there is a risk of lowering the adhesive strength, and when it is 30 g / m ² or more, the pressure-sensitive adhesive protrudes, and This is because problems such as an increase in the winding diameter may occur despite the small number of rolls. Usually, the solid content coating amount is measured by a weight method. In addition, the solid content coating amount in the present specification is a coating amount corresponding to the solid content amount of the pressure-sensitive adhesive layer forming coating solution, for example, in a pressure-sensitive adhesive layer forming coating solution using a solvent. The weight excluding the solvent is the weight of the pressure-sensitive adhesive itself in the solventless pressure-sensitive adhesive layer forming coating solution.

(2) Constituent Components of Adhesive Layer Next, constituent components of the adhesive layer used in the present invention will be described. The constituent component of the pressure-sensitive adhesive layer used in the present invention is not particularly limited as long as a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having the loss tangent tan δ within the above range is used. And additives such as a crosslinking agent.
Hereinafter, the adhesive which is a component of the adhesive layer of the present invention will be described in detail.

  Usually, the adhesive is a rubber-based, acrylic-based, vinyl ether-based, urethane-based, or silicone-based resin, as well as a tackifying resin, a crosslinking agent, an antioxidant, or an extender that develops adhesiveness as necessary. It is composed of components of additives such as ultraviolet absorbers. Examples of the form include a solvent type, an emulsion type, a hot melt type, and an energy ray curable type.

  The pressure-sensitive adhesive used in the present invention is not particularly limited as long as it can form a pressure-sensitive adhesive layer having the above loss tangent tan δ within the above range. Specifically, the single weight of the (meth) acrylate monomer is not limited. An acrylic pressure-sensitive adhesive of a copolymer, a copolymer such as (meth) acrylate and other monomers is preferred from the viewpoint of die-cutting properties and weather resistance. Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, octyl (meth) ) Acrylate, decyl (meth) acrylate, benzyl (meth) acrylate, and the like. For example, “(meth) acrylate” in the present specification means methacrylate or acrylate.

  Other monomers that form a copolymer with the (meth) acrylate include vinyl monomers containing an acrylic group, vinyl monomers having an epoxy group, vinyl monomers having an alkoxyl group, vinyl monomers having an ethylene oxide group, Vinyl monomer having amino group, vinyl monomer having amide group, vinyl monomer having halogen atom, vinyl monomer having phosphoric acid group, vinyl monomer having sulfonic acid group, vinyl monomer having silane group, vinyl monomer having phenyl group , Vinyl monomers having a benzyl group, vinyl monomers having a tetrahydrofurfuryl group, and other copolymerizable monomers.

(Crosslinking agent)
The cross-linking agent used in the present invention is not particularly limited as long as the cross-linking agent improves the cohesive force of the pressure-sensitive adhesive and can form a pressure-sensitive adhesive layer having the loss tangent tan δ within the above range. Is, for example, an aliphatic or aromatic organic compound having at least two, usually 2 to 6, preferably 2 to 4, functional groups in the molecule, wherein the functional group is an epoxy group, an isocyanate group, Examples include organic compounds having a hydroxyl group, an amino group, and the like. Examples of such a cross-linking agent include a room temperature cross-linking cross-linking agent or a heat cross-linking cross-linking agent.
The room temperature crosslinking type crosslinking agent is a crosslinking agent that crosslinks the pressure-sensitive adhesive by an aging treatment under room temperature conditions. Examples of the room temperature crosslinking type crosslinking agent include an isocyanate compound, a polyfunctional epoxy compound, and a crosslinking agent using a metal chelate compound such as aluminum or titanium. Among them, an isocyanate compound or a polyfunctional compound can be used. It is preferable to use a crosslinking agent using an epoxy compound. These compounds may be used alone or as a mixture of two or more.
As such an isocyanate compound, specifically, a polyisocyanate compound, a trimer of a polyisocyanate compound, a urethane prepolymer having an isocyanate group at the terminal obtained by reacting a polyisocyanate compound and a polyol compound, or A trimer of such a urethane polymer can be used.
Further, specific examples of the polyisocyanate compound are not particularly limited, but 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene Examples include diisocyanate, diphenylmethane-4,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate. be able to.
Further, the polyfunctional epoxy compound is not particularly limited, but sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylol. Propane polyglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polybutadiene diglycidyl ether, etc. Can do.
On the other hand, the heat-crosslinking type crosslinking agent is a crosslinking agent that crosslinks the pressure-sensitive adhesive by an aging treatment under heating. As such a heat-crosslinking type crosslinking agent, for example, a methylol group-containing compound obtained by reacting formaldehyde with melamine, benzoguanamine, or urea, or a part or all of the methylol groups of the methylol group-containing compound is a fat. And compounds etc. etherified with a group alcohol.
The amount of the crosslinking agent added varies depending on the type of pressure-sensitive adhesive and cross-linking agent used, and is appropriately selected so that the loss tangent (tan δ) at 150 ° C. of the pressure-sensitive adhesive layer is within the above range. For example, when the acrylic pressure-sensitive adhesive is used, the addition amount of the crosslinking agent is preferably 0.005 parts by weight or more and 50 parts by weight or less, more preferably 0.01 parts by weight or more and 30 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. Parts by weight or less, more preferably 0.1 parts by weight or more and 20 parts by weight or less.

(Other additives)
Moreover, the adhesive layer used for this invention may contain additives other than the said crosslinking agent as needed. Such additives are not particularly limited as long as they do not hinder the formation of the pressure-sensitive adhesive layer having the loss tangent tan δ within the above range. For example, natural resins such as rosin, modified rosin, rosin And modified rosin derivatives, polyterpene resins, terpene modified products, aliphatic hydrocarbon resins, cyclopentadiene resins, aromatic petroleum resins, phenol resins, alkyl-phenol-acetylene resins, coumarone-indene resins, Examples include tackifiers such as vinyltoluene-α-methylstyrene copolymer, anti-aging agents, softeners such as oil, fillers, stabilizers, pigments, colorants, silane coupling agents, and the like.

(solvent)
In addition, the adhesive layer forming coating solution used for forming the adhesive layer usually contains an adhesive, an additive such as a crosslinking agent, and a solvent. As the solvent, the adhesive, and Although it is not particularly limited as long as it can dissolve or disperse an additive such as a crosslinking agent, specifically, water, methanol, ethanol, isopropyl alcohol, n-propyl alcohol, ethyl acetate, methyl ethyl ketone, acetone, Butyl acetate, toluene, xylene, benzene and the like are preferable, and water, methanol, ethanol, isopropyl alcohol, n-propyl alcohol, ethyl acetate and methyl ethyl ketone are more preferable.

(3) Formation method of adhesive layer Next, the formation method of the adhesive layer used for this invention is demonstrated. The method for forming the pressure-sensitive adhesive layer used in the present invention is not particularly limited as long as a heat-sensitive recording material having a pressure-sensitive adhesive layer having the loss tangent tan δ within the above range can be obtained. Examples thereof include a method of directly coating on the surface of the material and a transfer method, among which the transfer method is preferable.
The above transfer method is to form a coating film by applying a coating solution for forming an adhesive layer in which an additive such as the above-mentioned adhesive and a crosslinking agent is dissolved or dispersed in a solvent to a separator, In this method, a separator is disposed so that the coating film faces the substrate surface, and the coating film is laminated (transferred) onto the substrate surface. In the above transfer method, the coating film can be dried and crosslinked on the separator, so that the substrate and the ink receiving layer are dried and crosslinked by applying sufficient heat without considering thermal deformation. Has the advantage of being able to. The separator used in the transfer method is peeled off when the thermal recording material of the present invention is wound.
Further, the coating method of the pressure-sensitive adhesive layer forming coating solution is not particularly limited as long as it is a method that can be applied with a uniform coating amount, specifically, a comma coating method, Examples thereof include a roll coating method, a bar coating method, an air knife coating method, a gravure coating method, and an offset gravure coating method, among which a comma coating method and a roll coating method are preferable.

2. Release Layer Next, the release layer used in the present invention will be described. The release layer used in the present invention is formed on the outermost surface of the substrate, and is a layer that comes into contact with the above-mentioned pressure-sensitive adhesive layer when the heat-sensitive recording material is rolled up. The release layer has a function of preventing runnability due to sticking between a heat-sensitive recording material and a heat source such as a thermal head, a function of preventing so-called sticking, a function of improving surface gloss and improving a commercial value, and the like.

  In general, the release layer used in the present invention preferably contains a release layer forming resin and an additive so that the adhesive layer can be easily peeled off.

(1) Release Layer Forming Resin The release layer forming resin used in the present invention is not particularly limited as long as it can form a release layer having the above-described function, but is not limited to silicone resin or fluorine. It is preferable to use a base resin, and it is particularly preferable to use a curable silicone resin. As such a curable silicone resin, any reaction system such as an addition reaction system, a condensation reaction system, an ultraviolet ray or an electron beam curing system can be used.
Examples of such an addition reaction type silicone resin include those in which a polydimethylsiloxane having a vinyl group introduced at its terminal is reacted with a hydrodienesiloxane using a platinum catalyst to form a three-dimensional crosslinked structure.
In addition, as the silicone resin of the above condensation reaction system, for example, a polydimethylsiloxane having a terminal —OH group and a polydimethylsiloxane having a —H group at the terminal are subjected to a condensation reaction using an organotin catalyst to form a three-dimensional crosslinked structure. Can be mentioned.
Examples of the ultraviolet curable silicone resin include those that use the same radical reaction as ordinary silicone rubber cross-linkage as the most basic type, those that introduce photopolymerization by introducing an unsaturated group, and those that use onium salts with ultraviolet rays. Examples include those that decompose to generate a strong acid and then cleave the epoxy group to crosslink, and those that crosslink by the addition reaction of thiol to vinylsiloxane. In addition, an electron beam curing system in which a crosslinking reaction by a radical proceeds without using an initiator as in the case of an ultraviolet curable silicone resin is also included.

  Other examples of the resin for forming the release layer include ethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, and triloxy. Ethyl acrylate, nonylphenoxyethyl acrylate, tetrahydrofurfuryloxyethyl acrylate, 1,3-dioxolane acrylate, phenoxydiethylene glycol acrylate, benzyl acrylate, butoxyethyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, glycidyl acrylate, Carbitol acrylate, isobornyl acrylate Neopentyl glycol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, dicyclopentanyl diacrylate, butylene glycol diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, propylene oxide modified trimethylolpropane triacrylate, pentaerythritol Examples thereof include triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, tetramethylolmethane tetraacrylate, and the like.

  Furthermore, polyester (poly) acrylate, urethane (poly) acrylate, epoxy (poly) acrylate, polyol (poly) acrylate, and the like. Furthermore, cationic polymerization of 2-chloroethyl vinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, triethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, etc. A monomer can also be used. In addition, when mix | blending a cationically polymerizable monomer etc., a cationic polymerization initiator is required. Such a cationic polymerization initiator is not particularly limited as long as it is a substance that initiates cationic polymerization by electron beam irradiation, and examples thereof include diazonium salts, iodonium salts, sulfonium salts, and metallocene compounds.

(2) Other additives In the present invention, in addition to the release layer-forming resin, if necessary, a lubricant, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous silica, aluminum hydroxide Additives such as pigments such as barium sulfate, talc, kaolin, clay, calcined clay, urea / formalin resin filler, benzoguanamine resin filler, leveling agents, surfactants, plasticizers, and UV absorbers can be added as appropriate. .
The content of the lubricant is not particularly limited as long as the properties of the release layer forming resin are not impaired, but for example, 0.1 to 30 parts by weight with respect to 100 parts by weight of the release layer forming resin. Of these, 1 to 25 parts by weight is preferred.

(3) Film thickness of peeling layer Next, the film thickness of the peeling layer used for this invention is demonstrated. The thickness of the release layer used in the present invention is not particularly limited as long as it has the function of the release layer described above. Specifically, the thickness is 0.01 to 15 μm, particularly 0.1. It is preferable that it is 10-10 micrometers. If the film thickness is less than 0.01 μm, the release layer may not be able to sufficiently secure the necessary functions. Conversely, if the film thickness exceeds 15 μm, the print sensitivity may be significantly affected or the cost may be reduced. Because it is disadvantageous.

(4) Formation method of peeling layer Next, the formation method of the peeling film used for this invention is demonstrated. The method for forming the release film used in the present invention is not particularly limited as long as the release layer having the above-described function can be obtained. For example, a release layer forming coating solution is prepared and the release layer is formed on the heat-sensitive recording layer. And a method of curing by irradiating the formed coating film with an electron beam.

  The release layer-forming coating solution can be broadly classified into those using a solvent and those not using a solvent. In the present invention, it is preferable to use a solvent-free coating solution that does not use a solvent. . This is because the solventless coating liquid does not require a drying step, and therefore has the advantages that color development of the heat-sensitive recording layer due to heating, contamination of the heat-sensitive paper due to solvent impregnation, and curling of the substrate do not occur. Examples of the solventless coating liquid include an energy ray curable type, and a typical example is a silicone resin-based prepolymer. As the silicone resin-based prepolymer, a radical curable type and a cationic curable type are used, and as the radical curable prepolymer, silicone (meth) acrylate is exemplified. ("(Meth) acrylate" means "acrylate or methacrylate"). Specific examples include silicone (meth) acrylate having 3 to 30 acryloyl groups or methacryloyl groups in the molecule and a number average molecular weight of 500 to 5000.

Further, in the present invention, in order to adjust the releasability, crosslink density, flexibility, curing rate, etc. to the silicone (meth) acrylate, radical polymerization unsaturated groups may be included in various molecules as necessary. The prepolymer, the monomer, or both the prepolymer and the monomer can be mixed. Examples of such a prepolymer include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and the like. Examples of the monomer include methyl (meth) acrylate, diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. it can.
On the other hand, examples of the cationic curable silicone resin include a silicone oligomer and / or a mixture of a monomer and a photocationic polymerization catalyst into which a vinyl ether group or an epoxy group is introduced. Although it does not specifically limit as a photocationic polymerization catalyst, The compound well-known as a conventional photocationic polymerization catalyst, for example, a triaryl sulfonium salt, a triaryl iodonium salt, bis (dodecylphenyl) hexafluoroantimonate etc. are mentioned. .
Moreover, when using ultraviolet rays (or visible light) as energy rays, a photoreaction initiator is added. As the photoreaction initiator, radical polymerization type prepolymers, and in the case of monomers, acetophenones, benzophenones, benzoins, thioxanthones, etc. are used. These photoinitiators are added in an amount of about 0.1 to 10 parts by weight with respect to 100 parts by weight of the energy ray curable resin.

The energy rays are not particularly limited as long as these prepolymers and monomers can be crosslinked and polymerized, but usually ultraviolet rays or electron beams are used.
As the electron beam source, various electron beam accelerators such as Cockcroft-Walton type, bandecraft type, resonant transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type are used. As the ultraviolet light source, a light source such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a black light, a metal halide lamp is used.

  In such a solvent-free coating solution, the viscosity of the coating solution is preferably 10 to 10,000 cps, more preferably 10 to 10,000 cps, and particularly preferably 100 to 5000 cps. When the viscosity is lower than 10 cps, the heat-sensitive recording layer or the like is impregnated with the coating liquid for forming the release layer, or repellency occurs at the time of coating. This is because there is a possibility that a portion where the layer does not have a peeling function may be formed. On the other hand, if it is higher than 10,000 cps, the surface of the coating film becomes non-uniform and the color development sensitivity may be uneven.

Further, the coating amount of the solventless coating liquid is not particularly limited, but is, for example, in the range of 0.1 to 15 g / m ² by dry weight, particularly 0.5 to 10 g / m ^2. It is preferable. This is because if it is less than 0.1 g / m ² , the desired effect cannot be sufficiently obtained, and if it exceeds 15 g / m ² , there is a possibility that the recording sensitivity of the heat-sensitive recording material is lowered.

On the other hand, in the coating liquid using the solvent, the coating amount of the coating liquid using the solvent is not particularly limited, but is 0.1% by dry weight as in the case of the solventless coating liquid. to 15 g / ^{m 2,} it is preferably Among them, 0.5 to 10 g / ^{m 2.}

  Further, the solvent used in the coating solution is not particularly limited as long as it can dissolve or disperse the release layer forming resin. Specifically, water, methanol, ethanol, isopropyl alcohol , N-propyl alcohol, ethyl acetate, methyl ethyl ketone, acetone, butyl acetate, toluene, xylene, benzene and the like, and a solvent having a boiling point of 100 ° C. or lower is preferable from the viewpoint of preventing color development of the thermosensitive recording medium. .

  In addition, the method for applying the coating liquid for forming the release layer is not particularly limited, but specifically, a bar coating method, a roll coating method, an air knife coating method, a gravure coating method, an offset gravure method. Examples of the coating method include a gravure coating method, a roll coating method, and an offset gravure coating method.

3. Thermal recording layer Next, the thermal recording layer used in the present invention will be described. The heat-sensitive recording layer is usually a layer formed on a substrate and containing a heat-sensitive dye and a colorant. When the heat-sensitive dye contained in the heat-sensitive recording layer comes into contact with the colorant by heat, a color reaction is caused and desired characters and the like can be obtained.

  The film thickness of the heat-sensitive recording layer used in the present invention is not particularly limited as long as the function of the heat-sensitive recording layer can be sufficiently exerted. Specifically, it is 2 to 12 μm, particularly 3 to 10 μm. Preferably there is.

  The method for forming the thermosensitive recording layer used in the present invention is not particularly limited. For example, a thermosensitive dye and a colorant are dissolved in a solvent to prepare a thermosensitive recording layer forming coating solution. And a wet coating method in which the coating liquid is applied to the substrate. More specifically, a bar coating method, an air knife coating method, a rod blade coating method, a pure blade coating method, a short dwell coating method, and the like can be given.

Further, the coating amount of the thermosensitive recording layer forming coating solution is not particularly limited, but for example, it may be in the range of ^{2 to 20} g / m ² , especially 3 to 15 g / m ² in terms of dry weight. preferable.
Further, the ratio of the heat-sensitive dye and the colorant in the heat-sensitive recording layer-forming coating solution is appropriately selected in consideration of the combination of the heat-sensitive dye and the colorant. Specifically, It is preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 1 part by weight of the thermosensitive dye.
Hereinafter, members used for the heat-sensitive recording layer will be described.

(1) Heat-sensitive dye The heat-sensitive dye used in the present invention is not particularly limited as long as it causes a color reaction with a colorant described later by heat. -Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino Blue-coloring dyes such as -7-dibenzylamino-benzo [a] fluorane, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7- Green coloring dyes such as anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino- Red coloring dyes such as 6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, rhodamine (o-chloroanilino) lactam, 3-diethylamino-6,8-dimethylfluorane, 3- (N -Ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6- Methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluorane 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6 Til-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-ani Black coloring dyes such as linofluorane, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetra Chlorophthalide, 3-p- (p-dimethylaminoanilino) anilino-6-methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluorane, 3 , 6-bis (dimethylamino) fluorene-9-spiro-3 ′-(6′-dimethylamino) phthalide, and the like, which have an absorption wavelength in the near infrared region.

(2) Colorant The colorant used in the present invention is not particularly limited as long as it causes a color reaction with the thermosensitive dye by heat. 4′-isopropylidene diphenol, 4,4′-cyclohexylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, benzyl 4-hydroxybenzoate, 2,4′-dihydroxydiphenyl sulfone 4,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4′-methyldiphenylsulfone, 2,2 ′ -Bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether, 1,1-bis (4-hydroxyphene) L) Phenyl compounds such as 1-phenylethane, N- (p-tolylsulfonyl) carbamoyl acid-p-cumylphenyl ester, N- (p-tolylsulfonyl) carbamoyl acid-p-benzyloxyphenyl ester, N -(O-tolyl) -p-tolylsulfoamide, 4,4′-bis (Np-tolylsulfonylaminocarbonylamino) diphenylmethane, etc. having a —SO ₂ NH— bond in the molecule, p-chloro Zinc benzoate, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate, zinc 4- [3- (p-tolylsulfonyl) propyloxy] salicylate, 5- [p- (2-p-methoxyphenoxyethoxy) ) Cumyl] Zinc salts of aromatic carboxylic acids such as salicylic acid.

(3) Additive In addition, in the present invention, in addition to the above materials, if necessary, a storage stability improver that further increases the storage stability of the thermosensitive recording layer, a sensitizer that further increases recording sensitivity, and the like An agent or the like can also be contained.
Specific examples of the preservability improver include, for example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-thiobis (2-methyl-6-tert-butylphenol), 1, 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 2,2- Hindered phenol compounds such as bis (4-hydroxy-3,5-dibromophenyl) propane, 4,4′-diglycidyloxydiphenylsulfone, 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenylsulfone, Diglycidyl terephthalate, cresol novolac epoxy resin, phenol novolac epoxy resin, bisphenol A epoxy resin An epoxy compound such as a resin may be used. Although the usage-amount of the said storage improving agent is not specifically limited, Generally 4 weight part or less is preferable with respect to 1 weight part of thermosensitive dyes.

  Specific examples of the sensitizer include stearamide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, and p-tolylbiphenyl ether. Di (4-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, di (β -Biphenylethoxy) benzene, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p- Chill benzyl ester, and oxalic acid dibenzyl ester. Although the usage-amount of the said sensitizer is not specifically limited, Generally 4 weight part or less is preferable with respect to 1 weight part of thermosensitive dyes.

  Moreover, as an additive added to the coating liquid for heat-sensitive recording layer formation mentioned above, an adhesive agent can be mentioned, for example. Examples of the adhesive include oxidized starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, fully (partially) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, Diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, polyurethane latex, styrene / butadiene latex, acrylic System latex and the like.

  Examples of the auxiliary agent added to the thermal recording layer forming coating solution include kaolin, light (heavy) calcium carbonate, calcined kaolin, titanium oxide, magnesium carbonate, aluminum hydroxide, amorphous silica, urea / formalin. Pigments such as resin filler, surfactants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salt, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax And waxes such as UV absorbers, antifoaming agents, fluorescent dyes, and coloring dyes.

4). Substrate The substrate used in this step is not particularly limited as long as it can form the above-mentioned heat-sensitive recording layer, but specifically, high-quality paper (acidic paper, neutral paper) Synthetic paper, coated paper, impregnated paper, paper such as inter-paper reinforced paper, and films. These substrates are preferably selected and used as appropriate according to the application.

5. Other Layers In the present invention, in addition to the above-described layers, an intermediate layer or a protective layer may be provided as necessary. By providing the intermediate layer, it is possible to prevent the uncured release layer forming resin from reacting with the heat-sensitive recording layer and coloring, and by providing a protective layer, the strength of the heat-sensitive recording body can be further increased. Because it is possible.

(1) Intermediate layer In the present invention, the intermediate layer provided as necessary is usually formed on the thermosensitive recording layer.
The film thickness of the intermediate layer is not particularly limited as long as the function of the intermediate layer can be sufficiently exerted, but specifically 0.1 to 20 μm, particularly 0.1 to 10 μm. Is preferred.
The method for forming the intermediate layer is not particularly limited. For example, an intermediate layer forming resin is dissolved in a solvent to prepare an intermediate layer forming coating solution, and the coating solution is applied. The wet coating method to do can be mentioned. More specifically, a bar coating method, an air knife coating method, a rod blade coating method, a pure blade coating method, a short dwell coating method, and the like can be given.
The coating amount of the coating solution is not particularly limited, but is preferably in the range of 0.1 to 20 g / m ² by dry weight, for example.
Next, members used for the intermediate layer will be described.

(Interlayer forming resin)
As the intermediate layer forming resin for forming the intermediate layer, those generally used can be used, specifically, oxidized starch, enzyme-modified starch, cation-modified starch, esterified starch, Starches such as etherified starch, polyvinyl alcohols such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, methoxy cellulose, hydroxyethyl cellulose, fully (or incomplete) saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, silicon modified polyvinyl alcohol , Polyacrylamide, polyvinylpyrrolidone, acrylic amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali Salts, water-soluble polymers such as isobutylene / maleic anhydride copolymer alkali salt, casein; polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic ester, polybutyl methacrylate, styrene / butadiene copolymer, vinyl chloride, Mention may be made of latexes such as vinyl acetate copolymers, ethylene / vinyl acetate copolymers and styrene / butadiene / acrylic copolymers. Among these, complete (or incomplete) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol are preferable. In particular, acetoacetyl group-modified polyvinyl alcohol is preferred.

(Additive)
Furthermore, pigments such as kaolin, aluminum hydroxide, calcium carbonate, and fine particle silica can be added to the intermediate layer as necessary. It is preferable to add such an additive in the range of about 0 to 250% by weight with respect to the intermediate layer forming resin. In addition, the intermediate layer coating liquid may include a dispersant, an antifoaming agent, a coloring dye, a fluorescent dye, a curing agent, an auxiliary agent such as an ultraviolet absorber, zinc stearate, calcium stearate, carnauba wax, paraffin as necessary. A lubricant such as wax and ester wax can be added.

(2) Protective layer In this invention, the protective layer provided as needed is normally formed on the said intermediate | middle layer. A method for forming such a protective layer is not particularly limited. For example, a method in which a protective layer sheet and an intermediate layer are bonded to each other, and two rolls (nipple rolls) are applied under appropriate pressure. Etc. Moreover, a polyethylene terephthalate film etc. are used suitably as such a protective layer sheet. Moreover, it is preferable that it is 0.1-10 micrometers as a film thickness of the said protective layer.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Hereinafter, the present invention will be specifically described with reference to examples.

[Example 1]
Using commercially available thermal paper (trade name: 130LHB, manufactured by Ricoh Co., Ltd.), using an offset gravure coater, 100 parts of energy ray curable solventless silicone resin (BY24-551A, manufactured by Toray Dow Corning Silicone) and energy ray curable type A composition comprising 10 parts of a silicone resin fine particle (KMP590, manufactured by Shin-Etsu Chemical Co., Ltd.) having an average particle size of 2.0 μm by mixing and stirring a composition comprising 30 parts of a solvent silicone resin (BY24-551B, manufactured by Toray Dow Corning Silicone). were mixed and stirred, the coating amount is applied so that 2.0 g / m ² by dry weight, using an electron beam irradiation device performs cured by irradiation with an electron beam so that the irradiation amount becomes 3Mrad A release agent layer was formed.
Subsequently, a composition (crosslinking) comprising an acrylic adhesive (RE-339, manufactured by Soken Chemical Co., Ltd.) and a cross-linking agent (E-5C, Soken Chemical Co., Ltd.) as main components on the back surface of the base material. A coating amount was formed by applying an agent addition amount of 52 g / main agent of 1 kg) at a solid coating amount of 24 g / m ² by a comma coating method. Further, this coating film was dried to form a pressure-sensitive adhesive layer to obtain a heat-sensitive recording material.
The film thickness of the thermosensitive recording material thus obtained was measured by cross-sectional observation with an SEM (scanning electron microscope). Furthermore, the loss tangent (tan δ) at 150 ° C. of the thermosensitive recording material is determined by using a dynamic viscoelasticity device (manufactured by Rheometrics, solid viscoelasticity analyzer RSA-II) for the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. By measuring the dynamic viscoelasticity (DMA) under the measurement conditions of 1 Hz and raising the temperature from minus 50 ° C. to 200 ° C., and reading from the graph showing the temperature dependence of the dynamic viscoelasticity obtained by this measurement Obtained.

[Comparative Examples 1 and 2]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that when the pressure-sensitive adhesive layer was formed, the amount of the crosslinking agent to be added and the solid content coating amount were changed.

[Example 2]
When forming the pressure-sensitive adhesive layer, 1717DT (manufactured by Soken Chemical Co., Ltd.) was used as an acrylic pressure-sensitive adhesive, L-45E (Soken Chemical Co., Ltd.) was used as a cross-linking agent, and solid content coating A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the work amount was changed.

[Comparative Examples 3 and 4]
A thermosensitive recording material was obtained in the same manner as in Example 2 except that when the pressure-sensitive adhesive layer was formed, the addition amount of the crosslinking agent and the coating amount of the solid content were changed.

[Example 3]
When forming the pressure-sensitive adhesive layer, HV-C9300 (manufactured by Toagosei Co., Ltd.) was used as the acrylic pressure-sensitive adhesive, the cross-linking agent was not used, and the solid content coating amount was changed. Except for the above, a heat-sensitive recording material was obtained in the same manner as in Example 1.

[Comparative Example 5]
In the same manner as in Example 3 except that HV-C9400 (manufactured by Toagosei Co., Ltd.) was used as the acrylic pressure-sensitive adhesive when the pressure-sensitive adhesive layer was formed, and the solid content coating amount was changed. A heat-sensitive recording material was obtained.

[Evaluation]
Test 1 (adhesive component protrusion test), test 2 (adhesive strength test), test 3 (aging-promoting test), and test 4 (printing of the printer) were performed on the heat-sensitive recording materials obtained in the above Examples and Comparative Examples. Test).
The protrusion test of the pressure-sensitive adhesive component in Test 1 was performed by measuring the pressure-sensitive adhesive component protruding when a thermosensitive recording medium was placed in an atmosphere of 40 ° C. and 80% RH and a 10 kg load was applied. Specifically, the protrusion of the pressure-sensitive adhesive component in the longitudinal direction MD (Machine Direction) and the width direction TD (Tensil Direction) of the thermal recording material was measured.
The adhesive strength test of Test 2 is based on JIS-Z-0237-2000, and the thermosensitive recording material is applied to SUS as an adherend by reciprocating a 2 kg roller twice so that the pasting area is 25 mm × 50 mm. A 180 ° peel test was performed immediately after the attachment. For the peel test, a universal tensile tester manufactured by INSTRON, model number: 5565 was used.
In the time-dependent change acceleration test of Test 3, the thermal recording medium was placed in an atmosphere of 40 ° C. and 80% RH, and a 2 kg / cm ² pressure acceleration test was performed using a blocking tester. Was measured.
In the printer ejection test of Test 4, a roll sample of the above-mentioned thermal recording material was prepared, stored in a room temperature atmosphere for 1 week, then ejected with a printer, and the printer suitability (running property) and label suitability were examined.
The results obtained by these tests are shown in Table 1.

  As is clear from Table 1, when the loss tangent tan δ is in the range of 0.05 to 0.2, any of the adhesive component protrusion test, adhesive strength test, aging promotion test, and printer launch test Even in the case of, good results were obtained. On the other hand, Comparative Examples 1, 3, and 5 in which the peel force with time was high did not show good printer suitability due to sticking at the time of launch. In Comparative Examples 2 and 4, although sticking did not occur, the adhesive strength of the adhesive was low, and good label suitability was not exhibited.

It is a schematic sectional drawing which shows an example of the thermosensitive recording material of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Thermal recording layer 3 ... Release layer 4 ... Adhesive layer

Claims (4)

A substrate, a heat-sensitive recording layer formed on one surface of the substrate, a release layer formed on the heat-sensitive recording layer, and an adhesive layer formed on the other surface of the substrate A thermal recording medium comprising:
The heat-sensitive recording material, wherein the pressure-sensitive adhesive layer has a loss tangent tan δ at 150 ° C. of 0.05 to 0.2.   The heat-sensitive recording material according to claim 1, wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive and a crosslinking agent.   The heat-sensitive recording material according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 30 µm. The solid content coating amount of the coating liquid for forming the pressure-sensitive adhesive layer used for forming the pressure-sensitive adhesive layer is 5 to 30 g / m ² , and any one of claims 1 to 3 The heat-sensitive recording material according to any one of the claims.

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