JP4949703B2 - Heat-sensitive adhesive and heat-sensitive adhesive sheet - Google Patents

Description

  The present invention relates to a heat-sensitive adhesive and a heat-sensitive adhesive sheet using the same.

In recent years, the use of pressure-sensitive adhesive sheets for labels such as labels for price display, labels for product display (barcode), labels for quality display, labels for weighing display, labels for advertising (stickers) has increased. ing.
There are various recording methods such as an inkjet recording method, a thermal recording method, and a pressure sensitive recording method.
Conventionally, a general pressure-sensitive adhesive sheet having a structure in which a pressure-sensitive adhesive layer and release paper are laminated on the surface opposite to the information recording surface of a label can be simply attached by simply peeling off the release paper at the time of bonding. Because it is widely used.
However, the pressure-sensitive adhesive sheet having a general configuration is used by peeling the release paper, but the peeled release paper is hardly collected and reused and is almost always disposed of.
Therefore, in recent years, attention has been paid to a heat-sensitive adhesive sheet that does not exhibit adhesiveness at room temperature and does not require a release paper.

In addition, as described in Non-Patent Document 1, the heat-sensitive adhesive basically contains a heat-meltable substance such as a thermoplastic resin and a solid plasticizer and, if necessary, a tackifier. It will be.
Thermoplastic resins impart adhesive strength and adhesive strength, and hot melt materials are solid at room temperature, so they do not give plasticity to resins, but they melt by heating to swell or soften the resin. Adhesiveness is developed.
The tackifier also works to improve the tackiness.
The heat-sensitive adhesive having such a configuration is an important point that determines the performance of how to bring out the adhesive properties of a thermoplastic resin when the adhesiveness is manifested by heat. The following two can be mentioned.
(1) Compatibilized state of the heat-meltable substance in the heat-sensitive adhesive and the thermoplastic resin (2) Elimination of the adhesion-inhibiting substance in the heat-sensitive adhesive Normally, the heat-meltable substance in the heat-sensitive adhesive is Although it melts by heating and forms a mixture with the resin, solidification and crystallization progress with time, and the adhesiveness is expected to decrease. ing.
Furthermore, when preparing the heat-sensitive adhesive, the heat-meltable substance used together with the thermoplastic resin is generally used in a finely pulverized dispersion state. A water-soluble polymer (protective colloid agent) such as an activator or polyvinyl alcohol is used as a dispersant. When these dispersants, particularly polymer compounds, are used, adhesion inhibition is caused and the adhesiveness is reduced. It has become.
As described above, the heat-sensitive adhesive has a problem in terms of quality, such as a decrease in the adhesive strength due to the inhibition of the adhesion of the constituent material in addition to a decrease in the adhesive strength with time after the occurrence of adhesiveness.

In order to solve such problems, investigations have been made on constituent materials such as thermoplastic resins and hot-melt materials, and improvements from the viewpoint of construction.
For example, in Patent Document 1 and Patent Document 2, as the thermoplastic resin, an ethylene-vinyl acetate copolymer having a glass transition point of 0 ° C. or higher or a thermoplastic resin having a glass transition point of −5 ° C. or higher (ethylene-vinyl acetate). It has been proposed to use (excluding copolymers).
However, these have relatively good adhesive strength to stainless steel plates, but the adhesive strength to vinyl chloride wrap, polyolefin wrap, cardboard, etc. has not yet reached a practical level.
The use of the heat-sensitive adhesive is not particularly limited. For example, in addition to the heat-sensitive adhesive sheet provided with a layer made of a heat-sensitive adhesive (referred to as a heat-sensitive adhesive layer) on one side of the substrate, in addition to the heat-sensitive adhesive layer And a thermosensitive pressure-sensitive adhesive sheet having a thermosensitive coloring layer on the other surface of the substrate.
These are expected to be used for so-called food POS, in which various food products are packaged in wraps and pasted on the wraps. However, conventional heat-sensitive adhesives have insufficient adhesive strength to vinyl chloride wrap, polyolefin wrap, corrugated cardboard and the like, which hinders practical application of the heat-sensitive adhesive sheet itself.

Patent Document 3 discloses a heat-sensitive adhesive sheet in which an undercoat layer containing non-foamed hollow particles is provided between a base material and a heat-sensitive color-developing layer, wherein the heat-sensitive adhesive uses dicyclohexyl phthalate as a solid plasticizer. A product using a sticky adhesive has been proposed.
Since this thermosensitive adhesive sheet is provided with an undercoat layer, it is at a level that is almost satisfactory in terms of improving the thermal sensitivity of the thermosensitive coloring layer and preventing the background coloring of the thermosensitive coloring layer that occurs when the thermosensitive coloring layer is made. Regarding the blocking property that occurs when the two layers are superposed, it occurs at about 40 ° C. and does not reach about 50 ° C., which is expected as a practical level.
On the other hand, as for the investigation on the dispersant, there is no obvious examination in the area of the heat-sensitive adhesive, and there is no description in the claims of the patent publication, but various examples are used in the description of the examples. You can see that
Examples include an anionic surfactant (sulfonate type), an anionic surfactant (carboxylate type), an anionic surfactant (polycarboxylic acid type), and the like. (Patent Literature 4, Patent Literature 5, etc.) In general, various modified types of polyvinyl alcohol and the like are also widely used as aqueous dispersants (protective colloid agents).

JP-A-6-57226 JP-A-6-57233 JP-A-9-265260 JP 2004-114559 A JP 2003-114559 A "Adhesion Handbook" 12th edition, pp. 131-135, published in 1970

  An object of the present invention is to overcome the drawbacks found in conventional heat-sensitive adhesives, maintain adhesive strength for a long time after the development of adhesiveness by heating, and increase adhesive strength.

（ｎ、ｍは整数をあらわし、分子量５００以上）
本発明の第２は、前記一般式（Ｉ）であらわされる分散剤の構造にしめる、エチレンオキサイド（ＥＯ）含有量が、５０重量％以上であることを特徴とする請求項１記載の感熱性粘着剤に関する。
本発明の第３は、前記一般式（Ｉ）であらわされる分散剤の熱溶融性物質に対する含有率が、５〜１０重量％であることを特徴とする請求項１または２記載の感熱性粘着剤に関する。
本発明の第４は、該感熱性粘着剤中に粘着付与剤を含有することを特徴とする請求項１〜３のいずれかに記載の感熱性粘着剤に関する。
本発明の第５は、請求項１〜４のいずれかに記載の感熱性粘着剤からなる層（感熱性粘着剤層）を基材の片面に設けてなることを特徴とする感熱性粘着シートに関する。
本発明の第６は、該感熱性粘着剤層と基材との間に、微小中空粒子とバインダーを主成分とする中間層を設けることを特徴とする請求項５に記載の感熱性粘着シートに関する。
本発明の第７は、基材に対し感熱性粘着剤層の反対面にロイコ染料と顕色剤を主成分とする感熱記録層を設けることを特徴とする請求項５または６記載の感熱性粘着シートに関する。 In order to solve the above-mentioned problems, the present inventors have conducted extensive studies on a dispersant for a hot-melt material, and as a result, by using a compound represented by the following general formula (I) as a dispersant, The inventors have found that it is possible to improve the characteristics with time and the adhesive strength level, and have completed the present invention.
A first aspect of the present invention is a thermosensitive adhesive mainly composed of a thermoplastic resin and a heat-meltable substance that has an action of developing adhesiveness by melting or softening the resin upon heating. The present invention relates to a heat-sensitive adhesive, characterized in that a compound represented by the following general formula (I) is used as a dispersant for a hot-melt material dispersion used in the preparation of
Formula (I)

(N and m are integers and have a molecular weight of 500 or more)
The second of the present invention is the heat-sensitive adhesive according to claim 1, wherein the content of ethylene oxide (EO) in the dispersant structure represented by the general formula (I) is 50% by weight or more. It relates to the agent.
The third aspect of the present invention is the heat-sensitive adhesive according to claim 1 or 2, wherein the content of the dispersant represented by the general formula (I) with respect to the heat-meltable substance is 5 to 10% by weight. It relates to the agent.
4th of this invention is related with the heat sensitive adhesive in any one of Claims 1-3 which contains a tackifier in this heat sensitive adhesive.
A fifth aspect of the present invention is a heat-sensitive adhesive sheet, comprising a layer (heat-sensitive adhesive layer) comprising the heat-sensitive adhesive according to any one of claims 1 to 4 on one side of a substrate. About.
6th of this invention is providing the intermediate layer which has a micro hollow particle and a binder as a main component between this heat-sensitive adhesive layer and a base material, The heat-sensitive adhesive sheet of Claim 5 characterized by the above-mentioned. About.
The of the present invention 7, the heat-sensitive according to claim 5 or 6, wherein the provision of the heat-sensitive recording layer mainly composed of leuco dye and a developer on the opposite surface of the heat-sensitive adhesive layer to the substrate It relates to an adhesive sheet.

Heat-sensitive adhesive is generally adhesive strength by heating, the thermoplastic resin is the main component which imparts adhesion, melted by heating 及 beauty, a thermally fusible substance having an effect of expressing the adhesiveness to the adhesive main Ingredients.
The heat-sensitive adhesive of the present invention is composed of a thermoplastic resin, a dispersant, and a heat-meltable substance, and the heat-meltable substance is melted by heating to exhibit adhesiveness. Such a heat-sensitive adhesive is usually formed by blending the constituent components in the form of a solution or a dispersion, so that it is added to components such as a thermoplastic resin, a dispersant, and a hot-melt material. In addition, components such as a tackifier are also contained.
As such a dispersant, a protective colloid composed of a surfactant or a water-soluble resin is generally used in many cases. However, these components are likely to cause adhesion inhibition in the heat-sensitive adhesive, and are inherently adhesive. The characteristic is deteriorated.

（ｎ、ｍは整数を表し、分子量５００以上）
この化合物は、ポリエチレン鎖にエチレンオキサイド鎖が結合したものであり、分子量としては、数百から３０００程度のオリゴマーに相当するものであり、優れた分散性を有するだけでなく、ポリエチレン鎖の存在によって、感熱性粘着剤中の熱可塑性樹脂との相溶性にすぐれることから、加熱によって粘着性が発現した際に被分散物である熱溶融性物質の熱可塑性樹脂に対する相溶性を向上させることができ、粘着性の経時安定性の向上に寄与することができる。
尚、ここでいう分子量は、浸透圧法による平均分子量である。
このような一般式であらわされる化合物としては、ノニオン系界面活性剤であるポリオキシエチレンアルキルエーテルなども存在するが、これらの界面活性剤は分子量が小さく分散剤として用いた場合に、低分子成分として系内に存在することから、粘着性に対して悪影響を及ぼしやすい。
その理由は明らかではないが、一般式（Ｉ）の構造を持ちながら、分子量が低い界面活性剤が系内に存在することで、感熱性粘着剤としての凝集力が低下することから、粘着力が低くなってしまうのではないかと考えている。
また、低分子の界面活性剤が多く存在することで、感熱性粘着剤層に対する支持体の反対側の面への影響も発生しやすく、ロール形態で保管した場合に界面活性剤が、感熱記録紙やインク受容層側へ移行してしまうことも起こりやすくなる。
このような点から、本発明の一般式（Ｉ）であらわされる化合物は、類似構造を有する他の化合物より優れた特性をあらわすものと考えられる。
また、熱可塑性樹脂、熱溶融性物質との相溶性に優れる特性を有していることから、他の界面活性剤やポリビニルアルコールをはじめとする水溶性高分子系の保護コロイド剤のように粘着阻害を引起すことなく、高い粘着力を発現することができる。 Under such circumstances, in the present invention, by using a compound represented by the following general formula (I) as a dispersant, it is possible to maintain high adhesive strength over time without causing adhesion inhibition. Become.
Formula (I)

(N and m represent integers and have a molecular weight of 500 or more)
This compound is one in which an ethylene oxide chain is bonded to a polyethylene chain, and the molecular weight corresponds to an oligomer of several hundred to about 3000, and not only has excellent dispersibility, but also due to the presence of the polyethylene chain. Because it has excellent compatibility with the thermoplastic resin in the heat-sensitive adhesive, it is possible to improve the compatibility of the hot-melt material that is the dispersion to the thermoplastic resin when the adhesiveness is manifested by heating. It can contribute to the improvement of the adhesive stability over time.
In addition, the molecular weight here is an average molecular weight by an osmotic pressure method.
As compounds represented by such a general formula, there are nonionic surfactants such as polyoxyethylene alkyl ethers, etc., but these surfactants have low molecular weight components when used as a dispersant because of their low molecular weight. Since it is present in the system, it tends to adversely affect the tackiness.
The reason for this is not clear, but the cohesive strength as a heat-sensitive adhesive decreases due to the presence of a low molecular weight surfactant in the system while having the structure of general formula (I). I think that will become low.
In addition, the presence of many low-molecular-weight surfactants easily affects the opposite side of the support relative to the heat-sensitive adhesive layer. It tends to occur to the paper or ink receiving layer side.
From such points, the compound represented by the general formula (I) of the present invention is considered to exhibit characteristics superior to those of other compounds having a similar structure.
In addition, since it has excellent compatibility with thermoplastic resins and hot-melt materials, it is sticky like other surfactants and protective colloids of water-soluble polymers such as polyvinyl alcohol. High adhesive force can be expressed without causing inhibition.

The characteristics of this compound are determined by the molecular weight and the proportion of ethylene oxide (hydrophilic site) in the molecule, and the molecular weight is preferably about 2000 or less.
Moreover, the hydrophilicity as a dispersing agent has been decided by the ratio of the ethylene oxide chain in the molecule, and the value is preferably 50% (NMR calculated value) or more.
Specific examples of the compound represented by the general formula (I) include Unitox series manufactured by Toyo Petrolite Co., Ltd.
Specific product names include Unitox 420 (molecular weight 560, EO content 20%), Unitox 450 (molecular weight 900, EO content 50%), Unitox 480 (molecular weight 2250, EO content 80%), Unitox. 520 (molecular weight 700, EO content 20%), Unitox 550 (molecular weight 1100, EO content 50%), Unitox 720 (molecular weight 875, EO content 20%), Unitox 750 (molecular weight 1400, EO content 50%) There is.

Furthermore, since the heat-meltable substance used in the heat-sensitive adhesive of the present invention is solid at room temperature, it does not give plasticity to the resin, but it develops adhesiveness by melting or swelling the resin by heating, Since it slowly crystallizes after being melted by heating, the adhesiveness can be maintained for a long time even after the heat source is removed.
As the hot-melt material, benzotriazole, hindered phenol, ester compound, phosphorus compound (phosphate ester compound, phosphine compound), or the like can be used.
As these heat-meltable substances, those which are solid at room temperature and melt upon heating are used.
The melting point of these compounds is preferably 70 ° C. or higher, and more preferably 80 ° C. or higher.
In this case, the upper limit of the melting point of the compound is about 200 ° C. When the melting point is less than 70 ° C., when a heat-sensitive adhesive material is used, there may be problems in storage, such as an adhesive force appearing at a normal storage environment temperature, and a heat-sensitive adhesive coating solution. In some cases, production troubles such as the development of adhesive strength may occur when coating and drying the coating on the support.
On the other hand, when the melting point exceeds 200 ° C., a large amount of energy is required to develop adhesive force, resulting in practical problems. In addition, when a thermal recording paper is used as a support and an adhesive force is developed with a large amount of energy, the thermal recording layer may be colored, and a printed image may not be read.
In addition, when two or more of these compounds are used in combination, the heat-sensitive energy can be lowered (higher sensitivity), and particularly when two or more types of structurally similar heat-meltable materials are used in combination. Therefore, it is possible to use a mixture of plural kinds of compounds as necessary.

前記一般式（II）において、Ｒ^１、Ｒ^２は、水素原子、炭素数１〜８のアルキル基、ベンジル基、α，α−ジメチルベンジル基の何れかを示し、Ｒ^３は水素原子、塩素原子の何れかを示す。
前記一般式（II）であらわされる化合物の具体例としては以下の化合物を挙げることができる。これらは、１種単独で使用してもよいし、２種以上を併用してもよい。
［（II）−１］５−クロロ−２（２′−ヒドロキシ−３′−ｔ−ブチル−５′−メチル）ベンゾトリアゾール
［（II）−２］５−クロロ−２（２′−ヒドロキシ−３′，５′−ジ−ｔ−ブチル）ベンゾトリアゾール
［（II）−３］２（２′−ヒドロキシ−３′−ｔ−ブチル）ベンゾトリアゾール
［（II）−４］２（２′−ヒドロキシ−３′−ｔ−ペンチル）ベンゾトリアゾール
［（II）−５］２（２′−ヒドロキシ−３′−メチル）ベンゾトリアゾール
［（II）−６］２〔２′−ヒドロキシ−３′，５′−ビス（α，α−ジメチルベンジル）〕ベンゾトリアゾール
［（II）−７］２（２′−ヒドロキシ−３′，５′−ジ−ｔ−ブチル）ベンゾトリアゾール
［（II）−８］２（２′−ヒドロキシ−３′，５′−ジ−ｔ−ペンチル）ベンゾトリアゾール
［（II）−９］２（２′−ヒドロキシ−３′，５′−ジ−ｔ−メチル）ベンゾトリアゾール
［（II）−１０］２〔２′−ヒドロキシ−５′−メチル−３′−（３，４，５，６−テトラヒドロフタルイミジルメチル）〕ベンゾトリアゾール
［（II）−１１］メチレンビス〔２−（２′−ヒドロキシ−５′−ドデカニルフェニル）ベンゾトリアゾール Examples of the benzotriazole-based compound include compounds represented by the following general formula (II).
Formula (II)

In the general formula (II), R ¹ and R ^{2 each} represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a benzyl group or an α, α-dimethylbenzyl group, and R ³ represents a hydrogen atom or chlorine. Indicates any atom.
Specific examples of the compound represented by the general formula (II) include the following compounds. These may be used individually by 1 type and may use 2 or more types together.
[(II) -1] 5-chloro-2 (2'-hydroxy-3'-t-butyl-5'-methyl) benzotriazole [(II) -2] 5-chloro-2 (2'-hydroxy- 3 ', 5'-di-t-butyl) benzotriazole [(II) -3] 2 (2'-hydroxy-3'-t-butyl) benzotriazole [(II) -4] 2 (2'-hydroxy -3'-t-pentyl) benzotriazole [(II) -5] 2 (2'-hydroxy-3'-methyl) benzotriazole [(II) -6] 2 [2'-hydroxy-3 ', 5' -Bis (α, α-dimethylbenzyl)] benzotriazole [(II) -7] 2 (2′-hydroxy-3 ′, 5′-di-t-butyl) benzotriazole [(II) -8] 2 ( 2'-hydroxy-3 ', 5'-di-t-pentyl) benzotriazole (II) -9] 2 (2'-hydroxy-3 ', 5'-di-t-methyl) benzotriazole [(II) -10] 2 [2'-hydroxy-5'-methyl-3'-( 3,4,5,6-tetrahydrophthalimidylmethyl)] benzotriazole [(II) -11] methylenebis [2- (2'-hydroxy-5'-dodecanylphenyl) benzotriazole

一般式（IV）

前記一般式（III）（IV）において、Ｒは、水素原子、炭素数１〜４の分岐していてもよいアルキル基を表し、例えば、メチル基、エチル基、プロピル基、ブチル基、ｔ−ブチル基、などが挙げられる。ｎは、１〜５の整数を表す。 Among the phosphorus compounds, phosphine compounds and phosphate ester compounds represented by the following general formula (III) and general formula (IV) can be given.
General formula (III)

Formula (IV)

In the general formulas (III) and (IV), R represents a hydrogen atom or an optionally branched alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, t- And a butyl group. n represents an integer of 1 to 5.

Examples of the compound represented by the general formula (III) include the following compounds. These may be used individually by 1 type and may use 2 or more types together.
[(III) -1] tri-2,4-xylenephosphine,
[(III) -2] tri-2,5-xylenephosphine,
[(III) -3] tri-2,6-xylenephosphine,
[(III) -4] tri-3,4-xylenephosphine,
[(III) -5] tri-3,5-xylenephosphine,
[(III) -6] Triphenylphosphine Specific examples of the compound represented by the general formula (IV) include compounds represented by the following general formula.
These may be used individually by 1 type and may use 2 or more types together.
[(IV) -1] Tris (o-methoxyphenyl) phosphine [(IV) -2] tris (m-methoxyphenyl) phosphine [(IV) -3] tris (p-methoxyphenyl) phosphine [(IV)- 4] Tris (p-ethoxyphenyl) phosphine [(IV) -5] tris (pn-propyloxyphenyl) phosphine [(IV) -6] tris (mt-butoxyphenyl) phosphine [(IV)- 7] Tris (mn-butoxyphenyl) phosphine [(IV) -8] tris (pn-butoxyphenyl) phosphine [(IV) -9] tris (pt-butoxyphenyl) phosphine [(IV) -10] Tris (mt-butoxyphenyl) phosphine

Furthermore, among the phosphorous compounds, phosphate compounds generally have a low melting point and few compounds are suitable for the heat-meltable material of the present invention, but the following compounds have a high melting point and can be mentioned as specific compounds.
[(V) -1] resorcinol bis [di (2,6-dimethylphenyl) phosphate]
[(V) -2] Hydroquinonebis [di (2,6-dimethylphenyl) phosphate]
In addition, the ester compound has a low melting point as in the case of the phosphoric ester compound, and there are few compounds suitable for the heat-meltable material of the present invention, but the following compounds have high melting points and can be mentioned as specific compounds.
[(VI) -1] Oxalic acid dibenzyl ester [(VI) -2] Oxalic acid di (p-methylbenzyl) ester [(VI) -3] p-hydroxybenzoic acid benzyl ester, isophthalic acid diphenyl ester [(VI) -4] phthalic acid diphenyl ester [(VI) -5] hydroquinone diacetate [(VI) -6] terephthalic acid dimethyl ester [(VI) -7] isophthalic acid dimethyl ester

Furthermore, in the present invention, various hindered phenol compounds can be used as the hot-melt compound, and specific compounds include the following compounds.
[(VII) -1] 1,3,5-tris (3 ′, 5′-di-t-butyl-4-hydroxybenzyl) isocyanuric acid [(VII) -2] 1,3,5-tris (3 ', 5'-di-t-butyl-4'-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H, 5H) trione [(VII) -3] 1,1,3-tris (2-Methyl-4-hydroxy-5-t-butylphenyl) butane [(VII) -4] 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane [(VII) -5] Tris (2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl) isocyanurate [(VII) -6] 4,4'-butylidenebis (3-methyl-6-tert-butylphenol)
[(VII) -7] stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate [(VII) -8] tetrakis [methylene-3- (3 ′, 5′-di- t-butyl-4'-hydroxyphenyl) propionate] methane [(VII) -9] 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane [(VII) -10] 1,3,5-trimethyl-2,4,6-tris (3 , 5-Di-tert-butyl-4-hydroxybenzyl) benzene [(VII) -11] 3,9-bis-1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5) -Methylphenylpropionyloxy) ethyl] -2,4 , 8,10-Etraoxaspiro [5,5] undecane

These hot-melt materials are used in a dispersed state, and as a dispersion method at that time, a dispersion method using a sand grinder, a ball mill, a paint shaker or the like, or various dispersion methods such as emulsification dispersion can be appropriately selected and used.
In the dispersion, the volume average particle diameter is preferably about 1 to 3 μm. Further, by making it finer such as 1 μm or less and 0.5 μm or less, the dynamic heat-sensitive sensitivity is increased, and it becomes compatible with the thermoplastic resin at low energy to become a heat-sensitive adhesive.
Further, not only the heat-sensitive sensitivity but also the storage stability at a normal storage environment temperature (in short, the blocking resistance is improved).
In the heat-sensitive adhesive of the present invention, the content of the heat-meltable substance in the heat-sensitive adhesive is preferably 25 to 80% by weight, more preferably 35 to 70% by weight.
If the content of the hot-melt material is less than 25% by weight or more than 80% by weight, the adhesive strength may be lowered.
In addition, when combined with a resin having a low glass transition point (Tg), if the content of the hot-melt material is less than 25% by weight, there are problems in storage such as the adhesive force is developed at a temperature in a normal storage environment. Arise.

Examples of the thermoplastic resin preferably used in combination with the heat-sensitive adhesive of the present invention include natural rubber latex, natural rubber latex, polyvinyl acetate, acrylic acid ester polymer, methacrylic acid ester polymer, and graft copolymerized vinyl monomers. Copolymers made of acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, and methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate and 2-ethylhexyl methacrylate. Polymer. Further, thermoplastic resins obtained by copolymerizing acrylonitrile, synthetic rubber, vinyl acetate-ethyl 2-ethylhexyl acrylate copolymer, vinyl acetate-ethylene copolymer, vinyl pyrrolidone-styrene copolymer, vinyl pyrrolidone-acrylic acid. Examples thereof include polymer resins such as ester copolymers and styrene-acrylic acid copolymers, but are not limited thereto.
The content of the thermoplastic resin in the heat-sensitive adhesive is preferably 10 to 60% by weight, more preferably 15 to 50% by weight. When the content of the thermoplastic resin is less than 10% by weight or more than 60% by weight, both are undesirable because the adhesive strength is lowered.
On the other hand, when the content of the low Tg resin exceeds 60% by weight, there are problems in storage such as an adhesive force developed at a normal storage environment temperature.

Furthermore, in order to improve the adhesive strength of the heat-sensitive adhesive, rosin derivatives, terpene resins, petroleum resins, phenol resins and xylene resins, which are tackifiers used in general adhesives for the above components, are used. used.
Examples of tackifiers that are particularly preferably used in the heat-sensitive adhesive of the present invention include rosin derivatives (rosin, polymerized rosin, hydrogenated rosin and esters thereof with glycerin, pentaerythritol, etc., resin acid dimers, etc.), terpene resins (Terpene resin, aromatic modified terpene resin, terpene phenol resin, hydrogenated terpene resin) and the like.
These tackifiers are compatible with the thermoplastic resin and the hot-melt material of the present invention, and the adhesive strength of the heat-sensitive adhesive is significantly improved.
Moreover, the melting point or softening point of the tackifier in the heat-sensitive adhesive is preferably 80 ° C. or higher, more preferably 80 to 200 ° C. When the temperature is less than 80 ° C., storage defects (decrease in blocking resistance) occur at normal storage environment temperatures.
Moreover, the content of the tackifier in the heat-sensitive adhesive is preferably 5 to 30% by weight, and more preferably 5 to 20% by weight. If it is less than 5% by weight, the adhesive strength is reduced, and if it exceeds 30% by weight, storage problems (decrease in blocking resistance) occur at temperatures in a normal storage environment.

In the heat-sensitive adhesive of the present invention, in addition to the above components, in order to prevent blocking, inorganic substances such as titanium oxide, alumina, colloidal silica, kaolin, talc, stearic acid metal salts, paraffin, natural wax, synthetic wax, A natural oil and fat, an organic substance such as polystyrene powder, and a dispersant, an antifoaming agent, a thickener and the like can be used as necessary.
By applying the heat-sensitive adhesive of the present invention to one surface of a substrate, a heat-sensitive adhesive sheet having strong adhesion to various adherends, particularly vinyl chloride wrap and polyolefin wrap, and also having good blocking resistance is obtained. be able to. This pressure-sensitive adhesive sheet is suitable for use as a label.
By applying a heat-sensitive recording layer on one side of the substrate and applying the heat-sensitive adhesive of the present invention on the other side, the adherence to each adherend, in particular vinyl chloride wrap and polyolefin wrap, is strong and anti-blocking. A heat-sensitive adhesive sheet for heat-sensitive recording with good properties can be obtained.
The drying conditions for coating or printing on the support must be dried within a temperature range in which the hot-melt material to be used does not melt. As a means for drying, in addition to hot air drying, a drying method using a heat source using infrared rays, microwaves, and high frequencies can be used.
The coating amount of the heat-sensitive adhesive layer, dry coating amount in the normal 2~35g / ^{m 2,} and preferably applied in the range of 5 to 25 g / ^{m 2.} When the coating amount of the heat-sensitive adhesive layer is less than 2 g / m ² , sufficient adhesion cannot be obtained when performing adhesion by heating. On the other hand, if it exceeds 35 g / m ² , the adhesion function is saturated, which is not economical.

In the heat-sensitive recording layer of the present invention, a heat-sensitive recording layer mainly composed of a leuco dye and a developer can be formed on the substrate.
As the leuco dye used in the heat-sensitive recording layer of the present invention, a leuco dye known in this type of leuco recording material is generally applied. For example, triphenylmethane, fluorane, phenothiazine, auramine, spiropyran And leuco compounds of dyes such as indolinophthalide are preferably used.
Specific examples of such leuco dyes include 3,3-bis (p-dimethylaminophenyl) phthalide and 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also called crystal violet lactone). 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7 , 8-Benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'- Trifluoromethylphenyl) amino} -6-diethylaminofluorane, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutyl Amino-7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-ani Linofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -5-methyl-7- N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrospirane, 3- (2 '-Hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'- Methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3-diethylamino-6-methyl-7 -(2 ', 4'-dimethylanilino) fluorane, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofur Oran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5- Chlor-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) Fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane 3-diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluorane, 3- (N-benzyl-N-cyclohexylamino) -5 6-benzo-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzofluorane, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p -Dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide, 3- (p-dimethyl) Aminophenyl) -3- (1-p-dimethylaminophenyl-1-phenylethylene-2-yl) phthalide, 3- (4′-dimethylamino-2′-methoxy) -3- (1 ″ -p-dimethyl) Aminophenyl-1 "-p-chlorophenyl-1", 3 "-butadiene-4" -yl) benzophthalide, 3- (4'-dimethylamino-2'-benzyloxy) -3- (1 "-p-dimethyl Aminophenyl-1 "-phenyl-1", 3 "-butadiene-4" -yl) benzophthalide, 3-dimethylamino-6-dimethylamino-fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl} -4,5,6,7-tetrachlorophthalide, 3-bis {1 1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7-dibromophthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, 3- (N -Methyl-N-propylamino) -6-methyl-7-anilidefluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorane spiro (9,3 ') -6'-dimethylaminophthalide, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilino Fluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidi -4 ', 5'-benzofluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilino Fluoran etc. can be mentioned.

In the heat-sensitive recording layer of the present invention, various electron-accepting compounds such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be applied as color developers. it can.
Specific examples thereof include 4,4'-isopropylidene bisphenol, 3,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis (o-methylphenol), 4,4'-secondary butylidene bisphenol, 4 , 4'-isopropylidenebis (o-tertiarybutylphenol), 4,4'-cyclohexylidenediphenol, 4,4'-isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl) -6-tertiarybutylphenol), 2,2'-methylenebis (4-ethyl-6-tertiarybutylphenol), 4,4'-butylidenebis (6-tertiarybutyl-2-methyl) phenol, 1,1,3 -Tris (2-methyl-4-hydroxy-5-tertiary butylphenol L) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-thiobis (6-tertiarybutyl-2-methyl) phenol, 4,4 ' -Diphenol sulfone, 4,2'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide, P-hydroxybenzoic acid Isopropyl acid, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5 -Bis (4-hydroxyphenylthio) -3-oxaheptane, 1,3 Bis (4-hydroxyphenylthio) -propane, 2,2'-methylenebis (4-ethyl-6-tertiarybutylphenol), 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N '-Diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, salicyl-o-chloroanilide, 2-hydroxy-3-naphthoic acid, zinc thiocyanate Antipyrine complex, zinc salt of 2-acetyloxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, zinc of hydroxynaphthoic acid, metal salts such as aluminum and calcium, bis- (4-Hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid Benzyl ester, 4- {β- (p-methoxyphenoxy) ethoxy} salicylic acid, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4 ′ -Diphenolsulfone, 3,3'-diallyl-4,4'-diphenolsulfone, antipyrine complex of α, α-bis (4-hydroxyphenyl) -α-methyltoluenethiocyanate, tetrabromobisphenol A, tetra Examples include bromobisphenol S, 4,4'-thiobis (2-methylphenol), 3,4-hydroxy-4'-methyl-diphenylsulfone, 4,4'-thiobis (2-chlorophenol), and the like.

In order to form the heat-sensitive recording layer of the present invention, a leuco dye and a developer may be bonded and supported on a substrate. In this case, various conventional binders can be used as appropriate.
Examples of such binders include polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, polyacrylic acid soda, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer Water-soluble compounds such as acrylamide / acrylic acid ester / methacrylic acid terpolymers, styrene / maleic anhydride copolymer alkali salts, isobutylene / maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, casein, etc. In addition to functional polymers, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polybutyl methacrylate, vinyl chloride / acetic acid Cycloalkenyl copolymer, ethylene / emulsion and styrene / butadiene copolymer vinyl acetate copolymer, it can be mentioned latices such as styrene / butadiene / acrylic copolymer.

Further, when the heat-sensitive recording layer is formed according to the present invention, various hot-melt materials can be used as fillers.
Specific examples thereof include fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, and fatty acids such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate. Metal salts, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, 1-hydroxy 2-naphthoic acid methyl ester, diphenyl carbonate, terephthalic acid dibenzyl ester, terephthalic acid dimethyl ester, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1, 2-bis (phenoxy) ethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-bis (phenoxy) butane, 1,4-bis ( Phenoxy) -2-butene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-bis (phenylthio) butane, 1,4-bis (phenylthio) -2-butene, 1, 2-bis (4-methoxyphenylthio) ethane, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl , P-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyldi Rufide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p- (benzyloxy) benzyl alcohol, 1,3-diphenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoyl Benzene, oxalic acid dibenzyl ester, 1,5-bis (p-methoxyphenyloxy) -3-oxapentane and the like can be mentioned.

In the present invention, auxiliary additives commonly used in this type of heat-sensitive recording layer, such as surfactants and lubricants, can be used in combination as required.
In this case, examples of the lubricant include higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, animal, vegetable, mineral, and petroleum-based waxes.
In the present invention, if necessary, for example, an undercoat layer is provided between the substrate and the heat-sensitive recording layer, or a water-soluble resin is used on the heat-sensitive recording layer for the purpose of improving image reliability. A protective layer having a main component can also be provided. In this case, as the components constituting these layers, the above-mentioned fillers, binders, hot melt materials, surfactants and the like can be used.
Furthermore, when the protective layer and the protective layer are not provided, a printed image can be formed directly on the heat-sensitive recording layer. For example, UV curable ink is used as the printing ink.

The heat-sensitive recording layer of the present invention can be formed by a generally known method.
For example, first, the leuco dye and the developer are separately pulverized and dispersed together with an aqueous binder solution by a dispersing machine such as a ball mill, an attritor, or a sand mill until the dispersed particle size becomes 1 to 3 μm, and a filler as required. A heat-sensitive recording layer can be formed by preparing a heat-sensitive recording layer coating solution by mixing with a heat-meltable substance (sensitizer) dispersion and the like, and applying it to a substrate.
By using the receiving paper for thermal transfer recording on the substrate and applying the heat-sensitive adhesive of the present invention on one side, it has strong adhesion to each adherend, especially vinyl chloride wrap and polyolefin wrap, and also has blocking resistance. A good heat-sensitive adhesive sheet for thermal transfer recording can be obtained.
An ink receiving layer mainly composed of a filler for thermal transfer recording medium and a water-soluble resin can be provided on one side of the receiving paper for thermal transfer recording of the present invention, and thermal transfer recording can be performed by applying a heat-sensitive adhesive on the other side. A heat-sensitive adhesive sheet can be obtained.
Further, the ink receiving layer can contain a water-proofing agent. It is optimal to use these adhesive sheets as labels.

In the ink receiving layer of the receiving paper for thermal transfer recording of the present invention, examples of the filler contained in the ink receiving layer include calcium carbonate, silica, titanium oxide, aluminum hydroxide, clay, fired clay, magnesium silicate, magnesium carbonate, White carbon, zinc oxide, barium sulfate, surface-treated calcium carbonate and silica, urea-formalin resin, styrene / methacrylic acid copolymer, fine powders such as polystyrene, etc. can be used, but are not limited thereto. is not.
As the water-soluble resin used in the ink receiving layer, various conventional water-soluble resins can be used as appropriate, such as polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose and the like. Cellulose derivatives, polyacrylic acid soda, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride co Examples include water-soluble polymers such as polymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein.
The ratio of the filler to the water-soluble resin in the ink receiving layer is related to the blocking property, and the content ratio (solid content) of the filler to the water-soluble resin is preferably 1: 0.1 to 0.2.
Specific examples of the water-resistant agent used in the ink receiving layer include formaldehyde, glyoxal, chrome alum, melamine, melamine-formaldehyde resin, polyamide resin, polyamide-epichlorohydrin resin, and the like.
The ratio of the water-proofing agent and the water-soluble resin is also related to the blocking property, and the content weight ratio (solid content) is preferably 0.3 to 0.5 with respect to the water-soluble resin 1.
As described above, the ink receiving layer is formed by containing a filler and a water-soluble resin, and further containing a water-soluble resin and a water-proofing agent in a specific ratio. Further, the surface of the ink receiving layer is smoothed by a calendar or the like. By processing at a temperature of 500 seconds or more, the print quality can be further improved in addition to the effect of the filler.

A heat-sensitive adhesive sheet can be obtained by applying the heat-sensitive adhesive of the present invention on various substrates, and as described above, an intermediate layer is provided between the substrate and the heat-sensitive adhesive layer. Can do. In the case of a pressure-sensitive adhesive sheet having a thermosensitive coloring layer on the side opposite to the thermosensitive adhesive layer, an undercoat layer can be provided between the substrate and the thermosensitive coloring layer.
When these intermediate layers and / or undercoat layers are provided, it is preferable to have heat insulation properties. By providing such a layer, the thermal sensitivity of the thermosensitive coloring layer is improved, and the thermosensitive coloring at the time of making the thermosensitive. The background coloration of the layer can be prevented, and the heat energy at the time of heat sensitivity can be utilized efficiently.
When said intermediate | middle layer and / or undercoat layer are heat insulation, it is hereafter called a heat insulation layer.
Examples of the heat insulating layer include a non-foaming heat insulating layer using fine hollow particles having a hollowness of about 30 to 95% or a porous pigment and a foaming heat insulating layer using a foaming filler.
Micro hollow particles having a hollowness of about 30 to 95% based on the thermoplastic resin used for the heat insulating layer contain air or other gas inside, and are already hollow micro particles. .
The volume average particle diameter of the fine hollow particles is preferably 0.2 to 20 μm, more preferably 0.5 to 10 μm. When the volume average particle diameter (particle outer diameter) is smaller than 0.2 μm, it is difficult to technically make it hollow and the role of the heat insulating layer becomes insufficient.
On the other hand, if the size is larger than 20 μm, the smoothness of the surface after coating and drying is lowered, so that the coating of the heat-sensitive adhesive layer becomes non-uniform. Must be applied.
Therefore, it is desirable that such a fine hollow particle distribution has a uniform distribution spectrum with a small variation and a particle diameter in the above range.
Further, in the present invention, plastic spherical hollow particles having a hollowness of 30% or more can be used, but those having a hollowness of 50% or more are more preferable. When the hollowness is less than 30%, the heat insulating property is insufficient, so that heat energy is released to the outside through the substrate and the heat efficiency of the pressure-sensitive adhesive activation is deteriorated.
The hollowness mentioned here is the ratio of the volume based on the outer diameter of the hollow microparticle to the volume based on the inner diameter.
As described above, the hollow microparticles used in the present invention are made of a thermoplastic resin, and the thermoplastic resin is preferably a copolymer resin mainly composed of vinylidene chloride and acrylonitrile.
Examples of the porous pigment used in the heat insulating layer of the present invention include organic pigments such as urea formaldehyde resin and inorganic pigments such as shirasu earth, but are not necessarily limited thereto.
In order to form the non-foaming heat insulating layer of the present invention, the above-mentioned fine hollow particles and porous pigment are dispersed in water together with a binder, and this is applied onto a substrate and dried. In this case, the coating amount of the fine hollow particles is at least 1 g per 1 m ² of the support, more preferably about 2 to 15 g.
The amount of the binder resin applied may be an amount sufficient to strongly bond the heat insulating layer to the substrate, and is usually 2 to 50% by weight based on the total amount of the fine hollow particles and the binder resin.

The binder used when forming the non-foaming heat insulating layer is appropriately selected from conventionally known water-soluble polymers and / or aqueous polymer emulsions.
Specific examples thereof include water-soluble polymers such as polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid. Ester copolymer, acrylamide / acrylic ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein Etc.
Examples of the aqueous polymer emulsion include latex such as styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic acid copolymer, and styrene / acrylic acid ester copolymer. And emulsions such as acrylic ester resins and polyurethane resins.

The foamable filler used in the present invention is a hollow plastic filler containing a foaming agent of a low-boiling-point solvent inside with a thermoplastic resin as a base, and various types are applied. Is 2 to 50 μm in the unfoamed state, and 10 to 100 μm, preferably 10 to 50 μm in the foamed state.
Examples of the thermoplastic resin used as the plastic filler include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic acid ester, polyacrylonitrile, polybutadiene, and copolymers thereof.
Further, as the foaming agent contained in the bag, propane, butane or a mixture thereof is generally used.
In order to form a foamable heat insulating layer on a substrate, the above foamable plastic filler is applied and dried on a support together with a binder, and then a hot plate is adhered to the coated surface, and the plastic filler is heated and foamed. You can do it.
The coating amount of the plastic filler is at least 1 g as an unfoamed filler with respect to 1 m ² of the support, and preferably about ² to 5 g.
Moreover, the usage-amount of a binder should just be an amount which makes a foaming heat insulation layer bind | bond strongly with respect to a support body, and is 5 to the total amount of a non-foamed filler and a binder normally. 50% by weight.
The heating foaming temperature is a temperature at which the thermoplastic resin constituting the filler ridge is softened. The expansion ratio is usually 2 to 4 times, preferably about 2 to 3 times, and is appropriately selected so as to achieve the above foaming.

As described above, the surface of the foamable heat insulating layer formed on the base material is considerably uneven, so that the flat surface is smoothed by calendering after the foamable heat insulating layer is formed (after heating and foaming). In addition, if necessary, one or more undercoat layers can be provided on the surface or the lower surface of the foamable heat insulating layer.
In the heat insulating layer of the present invention, a filler, a hot-melt material (sensitizer), a surfactant and the like are used in combination with the fine hollow particles, the porous pigment or the foamable filler and the binder as necessary. be able to.
In this case, examples of the filler include inorganic fine powders such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica, and the like. Organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin and the like, and examples of the heat-meltable substance (sensitizer) include higher fatty acids or esters thereof. In addition to amides or metal salts, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, p- Examples thereof include benzylbiphenyl and other thermofusible organic compounds having a melting point of about 50 to 200 ° C.

In addition, the base material used in the present invention is not particularly limited, such as high-quality paper, art paper, coated paper, other than paper, polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate, Polyolefin films such as polypropylene and polyethylene, polystyrene films, films obtained by bonding these, and the like can be used.
Coating methods for providing the coating layer include blade coating method, gravure coating method, gravure offset coating method, bar coating method, roll coating method, knife coating method, air knife coating method, comma coating method, U comma coating method, and AKKU. Known coating methods such as coating method, smoothing coating method, microgravure coating method, reverse roll coating method, four or five roll coating method, dip coating method, falling curtain coating method, slide coating method, die coating method, etc. Is available.

  According to the present invention, there are provided a heat-sensitive adhesive and a heat-sensitive adhesive sheet that overcome the drawbacks found in conventional heat-sensitive adhesives and are excellent in adhesive strength to various adherends and in adhesive stability over time. Provided.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In addition, all the parts and% shown below are based on weight.

Example 1
[Liquid A] Compound of hot melt material dispersion [(II) -1] 30.0 parts Compound Y-1 of general formula (I) described in Table 1 (10% aqueous solution or dispersion) 30.0 parts water 40.00 parts A mixture having the above composition was dispersed using a sand mill so that the volume average particle size was 1.0 µm to obtain a dispersion [A1 solution].
[Liquid B] Thermosensitive adhesive liquid methyl methacrylate-butyl acrylate copolymer emulsion (Tg-62 ° C., nonvolatile content 50%) 10 parts Polymerized rosin emulsion (softening point 145 ° C., nonvolatile content 50%) 6.5 parts Heat-meltable substance dispersion liquid [A1 liquid] 3.3 parts Application of heat-sensitive adhesive liquid [B liquid] having the above composition to the back surface of single-side coated paper of 80 g / m ^{2 so} that the dry weight is 16 g / m ^2. It dried and the heat-sensitive adhesive sheet was obtained.

Example 2
A heat-sensitive adhesive sheet was produced in the same manner as in Example 1 except that Y-2 was used instead of the compound Y-1 shown in Table 1.

Example 3
A heat-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that Y-3 was used instead of the compound Y-1 shown in Table 1.

Example 4
A heat-sensitive adhesive sheet was produced in the same manner as in Example 1 except that Y-4 was used instead of the compound Y-1 shown in Table 1.

Example 5
A heat-sensitive adhesive sheet was produced in the same manner as in Example 1 except that Y-5 was used instead of the compound Y-1 shown in Table 1.

Example 6
In the preparation of the heat-meltable substance dispersion liquid [Liquid A] in Example 2, the same procedure as in Example 2 was carried out except that the amount of compound Y-2 (10% aqueous solution) listed in Table 1 was changed to 15 parts. Thus, a heat-sensitive adhesive sheet was prepared (in this case, the amount of water was adjusted according to the amount of Y-2 added).

Example 7
In the preparation of the heat-meltable substance dispersion liquid [Liquid A] in Example 2, the same procedure as in Example 2 was conducted except that the amount of compound Y-2 (10% aqueous solution) shown in Table 1 was changed to 10 parts. Thus, a heat-sensitive adhesive sheet was prepared (in this case, the amount of water was adjusted according to the amount of Y-2 added).

Example 8
In the preparation of the heat-meltable substance dispersion liquid [Liquid A] in Example 2, the same procedure as in Example 2 was conducted except that the amount of compound Y-2 (10% aqueous solution) shown in Table 1 was changed to 40 parts. Thus, a heat-sensitive adhesive sheet was prepared (in this case, the amount of water was adjusted according to the amount of Y-2 added).

Example 9
A heat-sensitive adhesive sheet was prepared in the same manner as in Example 2 except that the polymerization rosin emulsion (tackifier) was not added in the preparation of the heat-sensitive adhesive liquid [B liquid] in Example 2 (in this case, polymerization was performed). The amount of water was adjusted according to the amount of rosin emulsion).

Example 10
The intermediate layer composed of the following intermediate layer liquid [C liquid] was applied and dried between the single-side coated paper as the support and the heat-sensitive adhesive layer so that the adhesion amount after drying was 5 g / m ^2. A heat-sensitive adhesive sheet was produced in the same manner as in Example 2.

[C liquid] Intermediate layer coating liquid micro hollow particles (copolymer resin mainly composed of acrylonitrile / vinylidene chloride)
(Solid content concentration 41%, average particle size 3.6 μm, hollowness 90%) 14.6 parts 2-ethylhexyl acrylate / methyl methacrylate / styrene copolymer (Tg-65 ° C.) (solid content concentration 55.4 %, Showa High Polymer) 21.7 parts water 63.7 parts

Example 11
<Preparation of heat insulating layer for thermal recording>
[Liquid D] Coating liquid for forming non-foaming heat insulation layer Micro hollow particle dispersion Copolymer resin mainly composed of acrylonitrile / vinylidene chloride (solid content concentration 41%, average particle diameter 3.6 μm, hollowness 90%) 30 parts Styrene / butadiene copolymer latex (Tg + 4 ° C.) 10 parts Water 60 parts A mixture comprising the above composition was stirred and dispersed to prepare a non-foaming heat insulating layer forming coating liquid [E liquid].
<Adjustment of thermosensitive coloring layer solution>
[E liquid] Color developing agent dispersion 3-di-n-butylamino-6-methyl-7-anilinofluorane 20 parts polyvinyl alcohol (10% aqueous solution) 10 parts water 70 parts [F liquid] developer Dispersion 4-isopropoxy-4'-hydroxydiphenylsulfone 10 parts polyvinyl alcohol (10% aqueous solution) 25 parts calcium carbonate 15 parts water 50 parts Disperse using a sand mill to prepare [E liquid] and [F liquid], and then mix and stir so that [E liquid]: [F liquid] = 1: 8. A working solution [G solution] was obtained.
The [Liquid D] was applied and dried on the surface of the substrate so that the weight after drying was 4 g / m ² to provide a non-foaming heat insulating layer.
On top of this, the above-mentioned [G liquid] was applied and dried so as to have a weight of 5 g / m ² after drying to provide a thermosensitive coloring layer.
(Preparation of protective layer coating solution)
A protective layer primary dispersion was prepared by pulverizing and dispersing a mixture having the following composition in a vertical sand mill so that the volume average particle diameter was 1 μm or less.

[Primary dispersion for protective layer]
Aluminum hydroxide 20 parts by weight 10% by weight polyvinyl alcohol (PVA) aqueous solution 20 parts by weight Water 40 parts by weight Next, a protective layer coating solution having the following composition was prepared using the primary dispersion of the protective layer.
[Composition of protective coating solution]
Protective layer primary dispersion 10 parts by weight 10% by weight PVA aqueous solution 20 parts by weight 12.5% by weight epichlorohydrin aqueous solution 5 parts by weight 30% by weight zinc stearate dispersion 2 parts by weight Next, one-side coating applied in Example 1 Instead of the paper, the above thermal recording paper was used. Other conditions were the same as in Example 2, and a heat-sensitive adhesive label was produced.

Comparative Example 1
In Example 1, Example 1 was used except that carboxylic acid-modified polyvinyl alcohol (10% aqueous solution) was used in place of the compound (Y-1) described in the general formula (I) used in [Liquid A]. In the same manner, a heat-sensitive adhesive sheet was produced.

Comparative Example 2
In Example 1, Example 1 was used except that sulfonic acid-modified polyvinyl alcohol (10% aqueous solution) was used instead of the compound (Y-1) described in the general formula (I) used in [Liquid A]. In the same manner, a heat-sensitive adhesive sheet was produced.

Comparative Example 3
In Example 1, instead of the compound (Y-1) described in the general formula (I) used in [A liquid], a 10% aqueous solution of polyoxyethylene alkyl ether (Daiichi Kogyo Seiyaku Neugen ET-65) was used. A heat-sensitive adhesive sheet was produced in the same manner as in Example 1 except that it was used.

<Adhesive properties>
(1) Immediately after measuring the adhesive force The heat-sensitive adhesive sheet of the present invention was cut into a 40 mm × 150 mm rectangle, and using a thermal printing device TH-PMD manufactured by Okura Electric,
Head condition Each energy 0.5mJ / dot
Printing speed 4ms / line
Platen pressure 6kgf / line
The heat-sensitive adhesive sheet is made heat-sensitive under the following conditions.
Subsequently, it was affixed to the adherend (corrugated cardboard) in the longitudinal direction with a rubber roller of 2 kg under pressure, and was peeled after 2 minutes under the conditions of a peeling angle of 180 degrees and a peeling speed of 300 mm / min. The adhesive strength at that time was measured with a force gauge, and the values obtained by reading and averaging the data at 0.1 second intervals are shown in the table. The unit is gf / 40 mm, and it was carried out at 22 ° C. and 65% RH.
Table 2 shows the measurement results of the adhesive properties of Examples 1 to 10 and Comparative Examples 1 to 3.
The adhesive strength rank is
A: 1000 gf / 40 mm or more B: 500 gf / 40 mm or more Δ: 100 gf / 40 mm or more and less than 500 gf / 40 mm ×: 100 gf / 40 mm or less

<Delay>
In the same way as in the above <Adhesive properties> evaluation, after the adhesiveness of the heat-sensitive adhesive was expressed, it was left for 1 minute in an environment of 22 [deg.] C. and 65% RH, and then a 2 kg rubber was applied to the adherend (corrugated cardboard). Affixed in the longitudinal direction with a roller, and peeled after 2 minutes under the conditions of a peeling angle of 180 degrees and a peeling speed of 300 mm / min. The adhesive strength at that time was measured with a force gauge, and the values obtained by reading and averaging the data at 0.1 second intervals are shown in the table.

表２にあるように本発明の感熱性粘着剤及び感熱性粘着シートは、初期の粘着特性に優れるだけでなく、粘着性が発現してからの経時保管後の粘着性も高くディレード性に優れるものであることがわかる。
Table 2 shows the measurement results of the adhesive properties of Examples 1 to 10 and Comparative Examples 1 to 3.

As shown in Table 2, the heat-sensitive pressure-sensitive adhesive and heat-sensitive pressure-sensitive adhesive sheet of the present invention are not only excellent in the initial pressure-sensitive adhesive properties, but also have high pressure-sensitive adhesive properties after storage over time after the pressure-sensitive adhesive properties are exhibited, and excellent in delay properties. It turns out that it is a thing.

Claims (7)

Thermo-sensitive material used for preparing thermo-sensitive adhesives in thermo-sensitive adhesives mainly composed of thermoplastic resins and thermo-meltable substances that melt and melt when heated to develop adhesive properties A heat-sensitive adhesive, wherein a compound represented by the following general formula (I) is used as a dispersant for the dispersion.
Formula (I)

(N and m are integers and have a molecular weight of 500 or more)   The heat-sensitive adhesive according to claim 1, wherein the content of ethylene oxide (EO) in the dispersant structure represented by formula (I) is 50% by weight or more.   The heat-sensitive adhesive according to claim 1 or 2, wherein the content of the dispersant represented by the general formula (I) is 5 to 10% by weight.   The heat-sensitive adhesive according to any one of claims 1 to 3, further comprising a tackifier in the heat-sensitive adhesive. A heat-sensitive adhesive sheet comprising a layer (heat-sensitive adhesive layer) comprising the heat-sensitive adhesive according to any one of claims 1 to 4 on one side of the substrate. Between the heat-sensitive adhesive layer and the substrate, the heat-sensitive adhesive sheet according to claim 5 Symbol mounting, characterized in that an intermediate layer mainly composed of fine hollow particles and a binder. The heat-sensitive adhesive sheet according to claim 5 or 6, wherein a heat-sensitive recording layer mainly comprising a leuco dye and a developer is provided on the opposite surface of the heat-sensitive adhesive layer to the substrate.