JP2021183659A - Aqueous pressure-sensitive adhesive and adhesive sheet - Google Patents

Abstract

To provide a removable type aqueous pressure-sensitive adhesive that combines removability after using at a high-temperature of 100°C or higher (high-temperature removability) and durability, suppresses contamination due to high-speed peeling, does not increase a coagulation force before and after long term storage, even when used neutral paper as a surface substrate and can provide an adhesive sheet of which adhesive force does not decrease.SOLUTION: An aqueous pressure-sensitive adhesive comprises: a water dispersible polymer (A) having hydroxyl and carbonyl groups and no carboxyl group, and a reactive compound (C) having a functional group capable of reacting with at least any one of a hydroxyl group and a carbonyl group, in which the water dispersible polymer (A) is a copolymer of a mixture containing ethylenically unsaturated compounds (a1) to (a3), and the reactive compound (C) from 0.01 to 10 pts.mass relative to 100 pts.mass of the water dispersible polymer (A) is contained, and a compound that has an aromatic ring is not contained.SELECTED DRAWING: None

Description

The present invention relates to a water-based pressure-sensitive adhesive and an adhesive sheet using the same.

Pressure-sensitive adhesives are widely used in industrial fields such as packaging, construction, building materials, automobiles, and electronic parts, as well as in general households. The most common laminated structure of the adhesive sheet is "support (also known as base sheet) / adhesive layer / release liner" (single-sided pressure-sensitive adhesive sheet) or "release liner / adhesive layer / support (release liner / adhesive layer / support). Another name: base sheet) / adhesive layer / release liner ”(double-sided pressure-sensitive adhesive sheet). At the time of use, the release liner is peeled off and the adhesive layer is attached to the adherend. Adhesive sheets (hereinafter, pressure-sensitive adhesive sheets are abbreviated as adhesive sheets) are used for various purposes and require various adhesive strengths.

As a component of the pressure-sensitive adhesive, an elastic material such as natural rubber or synthetic rubber or an acrylic resin is used. Adhesive labels, adhesive sheets, adhesive tapes, etc., which are formed by forming a layer of these pressure-sensitive adhesives on the support surface of paper, plastic film, cloth, metal plate, etc., are applied to the adherend surface at room temperature with a pressure of about finger pressure. Since it can be easily adhered, it is widely used in various fields in various fields. It goes without saying that such adhesive labels are required not to easily fall off when attached to the adherend, but can be easily peeled off after a certain period of time after being attached to the adherend. Is often required.

For example, adhesive labels attached to various containers and adhesive tapes used for fixing parts in electrical equipment may be peeled off for recycling and reuse of adherends. Further, the adhesive tape such as masking tape attached to the adherend for painting and forming the sealing material is peeled off from the adherend after the coating film or the sealing material is dried and formed. .. Further, for example, an adhesive sheet such as a surface protective film attached to an adherend at the manufacturing stage of a product such as a display may be peeled off when the product is used.
In such a case, the adhesive strength varies greatly depending on the material of the adherend, changes over time after sticking to the adherend, changes in the environment such as temperature and humidity, etc., but changes in the adhesive strength due to these various factors Is very difficult to control. In particular, if the adhesive strength between the adhesive label and the adherend is too high, the pressure-sensitive adhesive remains on the adherend when trying to peel off, or the support is made of paper. Is destroyed (also known as substrate fracture), so-called paper tearing occurs, making re-peeling difficult. Further, if the adhesive strength between the adhesive label or the like and the adherend is too low, the adhesive label or the like can be easily peeled off, but the adhesion to the adherend or the like is not sufficient, and the purpose originally expected for the adhesive label or the like can be achieved. It will be difficult.

In recent years, in consideration of the protection of the global environment and the working environment, the number of water-based pressure-sensitive adhesives has begun to increase. Among them, a water-based pressure-sensitive adhesive containing an acrylic resin having excellent adhesiveness and weather resistance as a main component (hereinafter, may be simply referred to as an adhesive) has become widespread.
As the surface base material of the water-based pressure-sensitive adhesive, plastic film, synthetic paper, paper, metal foil and the like are used. Among them, adhesive sheets using paper base materials, which are the mainstream, are widely used for distribution management labels for foods and products, address display labels for delivery, raw fabrics for form printing such as copy tables, adhesive tapes, and the like. .. Conventionally, the paper used as the base material of the adhesive sheet has been mainly acid paper made by using aluminum sulfate for fixing the solvent-type rosin sizing agent (hereinafter referred to as acid paper). However, since aluminum sulfate is weakly acidic, there is a problem that cellulose, which is the main component of the fiber, is hydrolyzed and the paper deteriorates over time. Therefore, recently, paper made using a neutral sizing agent such as alkyl ketene dimer (AKD) or alkenyl succinic anhydride (ASA) (hereinafter referred to as acid-free paper) is widely used in consideration of storage stability. ing.
By the way, calcium carbonate has easy control of particle size, particle size distribution and particle shape, high whiteness and opacity, and low cost. However, since it dissolves under acidic conditions, it has not been used for acid paper so far, but in the case of acid-free paper, such calcium carbonate can now be used as a filler.

In addition, in order to raise awareness of environmental issues and protect forest resources in recent years, recycled paper containing used paper as a raw material is widely distributed as printing paper and copying paper. When making these recycled papers, the raw materials for used paper contain a large amount of neutral paper containing calcium carbonate. However, since the above-mentioned calcium carbonate dissolves under acidic conditions, acidic papermaking cannot be performed. Therefore, the papermaking of recycled paper is inevitably neutral papermaking, and the ratio of acid-free paper to the whole paper is increasing.
Even in the case of adhesive sheets, it is inevitable to switch from acid paper to acid-free paper as the surface base material, and in particular, it is possible to use acid-free paper, which is recycled paper, as the base material for surface base materials and release liners. It is needed.

However, conventional water-based pressure-sensitive adhesives are contained in the neutral paper or glossy paper containing calcium carbonate when the neutral paper or glossy paper is used as the base material of the surface base material or the release liner. Calcium ions are released from calcium carbonate and undergo a cross-linking reaction with the carboxyl group contained in the pressure-sensitive adhesive. Therefore, over time, such as during storage of the adhesive sheet or after peeling off the release liner and attaching it to the adherend. Therefore, there is a problem that the cohesive force of the adhesive layer is changed, the adhesive force is significantly reduced, and the curved surface adhesiveness is significantly reduced as compared with the case of using acidic paper.
However, conventional water-based pressure-sensitive adhesives use acid-free paper containing calcium carbonate, especially acid-free paper or glossy paper containing calcium carbonate as the surface base material, under high temperature and high humidity. It appears prominently when left in. Such a phenomenon that adversely affects the adhesiveness of the pressure-sensitive adhesive with acid-free paper is called "acid-free paper deterioration".

In such an environment, various attempts have been made to satisfy the above-mentioned various characteristics.
For example, in an adhesive sheet in which a surface base material containing a calcium component in a paper layer, an adhesive layer containing an acrylic copolymer as a main component, and a release liner are sequentially laminated, the calcium component in the surface base material can be used. , An adhesive sheet in which the carboxylic acid component of the acrylic copolymer in the adhesive layer is suppressed from being ionized has been studied. As the ionization suppressing means, specifically, the means shown in the following (1) to (3) and the like are disclosed.
(1) Reduce the carboxyl groups that cause cross-linking as much as possible (see Patent Document 1).
(2) Potassium sulfate, potassium pyrophosphate and the like are contained in the pressure-sensitive adhesive as a source of potassium ions having a higher ionization tendency than calcium ions and therefore more easily reacting with carboxylic acid than calcium ions.
(3) A chelating agent such as an ammonium salt of EDTA (ethylenediaminetetraacetic acid) is contained in the adhesive.

For example, (meth) acrylic acid alkyl ester (a1) containing an alkyl group having 4 to 12 carbon atoms is 50 to 99.8% by weight, a carboxyl group-containing unsaturated compound (a2) is 0.1 to 20% by weight, and is polyfunctional. A mixture containing 0.1 to 20% by weight of the unsaturated compound (a3) and 0 to 49.8% by weight of the other unsaturated compound (a4) is emulsified and polymerized in the presence of an anionic reactive surfactant. Disclosed is a removable water-based pressure-sensitive adhesive containing the water-dispersible polymer [A] and the cross-linking agent [B]. (See Patent Document 2).

For example, it contains a water-dispersible polymer obtained by emulsion-polymerizing an ethylenically unsaturated compound (A) containing an ethylenically unsaturated compound (a1) having a sulfonic acid group in the presence of a tackifier resin (B). A water-based pressure-sensitive adhesive is disclosed (see Patent Document 3).

For example, a polymer having a hydroxyl group or a carboxyl group and one or more cross-linking agents selected from the group consisting of metal alcoholates and boron-containing compounds are mixed in the presence of a lower alcohol, then molded, and at the same time as molding. Alternatively, a method for producing an adhesive molded product obtained by heat-crosslinking after molding is disclosed (see Patent Document 4).

For example, in an adhesive tape in which a crosslinked pressure-sensitive adhesive layer is provided on a flexible support, the crosslinked adhesive layer is a (meth) acrylic acid alkyl ester or an ester thereof and a (meth) acrylic acid alkoxyalkyl ester. A medical pressure sensitive adhesive tape comprising a crosslinked polymer of 99-99.9% by weight of the mixture and 0.1 to 1% by weight of a carboxyl group and / or a hydroxyl group-containing monomer. Therefore, it is disclosed that the crosslinked product is a crosslinked product made of a metal chelate compound (see Patent Document 5).

For example, (A) (a) 40 to 99% by weight of a (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms, (b) 1 to 20% by weight of an ethylenically unsaturated compound having a carboxyl group, and (c). ) A water-dispersible polymer of an acrylic copolymer obtained by copolymerizing a mixture of ethylenically unsaturated compounds 0 to 59% by weight other than the above components in an aqueous medium, and formula (B) M (Z). ) Anion (M in the formula is a polyvalent metal such as Cr, Cu, Zn, Ti, Zr, Mn, Fe, Co, and Anion is a carboxylic acid ion, a phosphate ion, a hydrogen phosphate ion, a chromate ion, an acetate. A removable water-based pressure-sensitive adhesive containing a composition consisting of a complex salt represented by one or more of ions and Z being ammonia or a volatile amine) as a main component is disclosed (Patent). See Document 6).

Japanese Unexamined Patent Publication No. 2002-338909 Japanese Unexamined Patent Publication No. 2004-256789 Japanese Unexamined Patent Publication No. 2009-256481 Japanese Unexamined Patent Publication No. 2003-210566 Japanese Unexamined Patent Publication No. 04-150865 Japanese Unexamined Patent Publication No. 58-176284

However, as the water-based pressure-sensitive adhesive described in Patent Document 1, the method (1) above is the most direct and effective method. However, in both solvent-based and water-based adhesives, the carboxyl group is an indispensable functional group for ensuring the holding power (cohesive power) of the adhesive layer. In particular, when the main component is an aqueous dispersion of a polymer obtained by emulsion-polymerizing a (meth) acrylic compound in an aqueous solution, that is, an aqueous medium, if emulsion polymerization is attempted without using a compound having a carboxyl group at all, polymerization will occur. The stability is extremely poor, and a large amount of agglomerates are generated. Even if the agglomerates are separated, the viscosity of the adhesive changes significantly over time. Furthermore, its performance as an adhesive is extremely insufficient.

It can be obtained by controlling the amount of the polymerization initiator, the amount of the chain transfer agent, etc. when an unsaturated compound having a carboxyl group is not used at all, or when a very small amount of at most 1% by weight or less is used. When the molecular weight of the polymer is reduced, the adhesive has a reduced holding force (cohesive force), so that the adhesive sheet apparently exhibits a certain degree of adhesive force, but because the holding force (cohesive force) is small, the adhesive sheet is covered. The so-called "glue residue" phenomenon, in which the adhesive layer is transferred to the adherend when it is peeled off from the adherend, becomes remarkable. That is, it does not satisfy the basic performance required for the removable pressure-sensitive adhesive.

In this case, when acid-free paper is used as the surface base material, the holding force (cohesive force) becomes significantly larger after storage under high temperature and high humidity than after storage under normal conditions, and on the other hand, the adhesive force is significantly increased. It is extremely difficult to suppress the deterioration of acid-free paper because it is lowered.

In addition, potassium is easier to ionize than calcium, and unlike calcium ions, the generated potassium ions do not form a crosslinked structure with the carboxyl group. Moreover, the cross-linking reaction is irreversible because calcium ions form a sparingly soluble salt with a carboxyl group. Therefore, even if potassium sulfate, potassium pyrophosphate, or the like is contained in the adhesive as in the method (2) above, cross-linking of calcium ions will eventually occur, which is an effective means as a countermeasure against acid-free paper deterioration. is not it.

The method (3) above is effective as a countermeasure against deterioration of neutral paper, but on the other hand, when a sequestrant such as EDTA is mixed with the adhesive, the viscosity of the adhesive is lowered and the coatability is reduced. Not only is it difficult to secure the adhesive layer, but also the adhesion between the pressure-sensitive adhesive layer and the base material is insufficient, and the adherend surface is contaminated with the sequestering agent (cloudiness, glue). The rest) may be seen.

Further, the water-based pressure-sensitive adhesive described in Patent Document 2 uses a polyfunctional unsaturated monomer and an anionic surfactant, so that the adhesive strength does not increase with time and is adhered at the time of re-peeling. It is stated that it has excellent stain resistance such as less contamination such as adhesive residue and sticking marks on the body, but since it has a carboxyl group, neutral paper deterioration occurs at high temperature and high humidity, and the adhesive strength decreases. It is hard to say that it is an effective method because it tends to be uncontrollable.

Further, in the water-based pressure-sensitive adhesive described in Patent Document 3, the ethylenically unsaturated monomer constituting the adhesive contains 2-acrylamide-2-methyl-1-propanesulfonic acid or a salt thereof. , The sulfonic acid group tends to significantly corrode the metal part of the coating machine due to the strong acid, and the deterioration of acid-free paper occurs under high temperature and high humidity, and it tends to be impossible to suppress the decrease in adhesive strength, so what is an effective method? It's hard to say.

Further, it is described that the water-based pressure-sensitive adhesive described in Patent Document 4 contains 1 or 2 or more selected from the group consisting of a metal alcoholate and a boron-containing compound as a cross-linking agent. Boric acid is used for the polymer containing a hydroxyl group, and metal alcoholate is used for the polymer containing a carboxyl group as a cross-linking agent. However, since the cross-linking reaction is too fast, the cross-linking forms a non-uniform pressure-sensitive adhesive layer. There is a possibility that it may cause contamination of the adherend (adhesive residue, cloudiness) when it is peeled off from the adherend, so it cannot be said to be an effective method.

Further, in the pressure-sensitive adhesive described in Patent Document 5, the use of a metal chelate, a metal alcoholate, or the like as a cross-linking agent for a hydroxyl group-containing polymer is specified, but cross-linking with only a metal chelate to a hydroxyl group has a weak bonding force. Therefore, it is known that the cross-linking system collapses under harsh conditions of high temperature and high humidity. Therefore, it is difficult to say that it is an effective method because it is easy to cause contamination of the adherend (glue residue, cloudiness) when it is peeled off from the adherend at high temperature.

Further, in the water-based pressure-sensitive adhesive described in Patent Document 6, the metal complex salt is dispersed in the adhesive layer to reduce the adhesiveness and impart removability, but the dispersed particles are aggregated under high temperature and high humidity. In some cases, the coatability may be significantly deteriorated, or the transferability to the adherend may cause a decrease in removability.

The problem to be solved by the present invention is that even when a potassium carbonate-containing paper such as acid-free paper is used as a base material, it is possible to form an adhesive layer in which deterioration of adhesiveness due to deterioration of acid-free paper is suppressed. In addition, a water-based feeling that achieves both durability and re-peelability after use at a high temperature of 100 ° C or higher (hereinafter referred to as high-temperature re-peelability) and suppresses contamination in high-speed peeling. It is to provide a pressure adhesive.

As a result of diligent studies to solve the above problems, the present inventors have found that the above object can be achieved by the removable water-based pressure-sensitive adhesive shown below, and have completed the present invention.

That is, an embodiment of the present invention is a reactive compound having a water-dispersible polymer (A) having a hydroxyl group and a carbonyl group and having no carboxyl group, and a functional group capable of reacting with at least one of the hydroxyl group and the carbonyl group. The water-dispersible polymer (A) containing (C) is a copolymer of a mixture containing the following ethylenically unsaturated compounds (a1) to (a3), and the water-dispersible polymer (A). A water-based pressure-sensitive adhesive containing 0.01 to 10 parts by mass of the reactive compound (C) with respect to 100 parts by mass and not containing a compound having an aromatic ring.
(A1) Ethylene unsaturated compound having an alkyl group having 4 to 24 carbon atoms (a2) Ethylene unsaturated compound having a hydroxyl group (a3) Ethylene unsaturated compound having a carbonyl group

The water-based pressure-sensitive adhesive of the present invention makes it possible to manufacture a re-peelable adhesive label having good adhesiveness and re-peelability to various adherends, which could not be realized by the conventional pressure-sensitive adhesive. became. In addition, the obtained adhesive sheet has improved cohesive force of the adhesive layer, so that both high-temperature removability and durability can be achieved.
Furthermore, since the water-dispersible polymer does not have a carboxyl group, it is possible to suppress a decrease in adhesiveness to calcium carbonate-containing paper such as acid-free paper as a surface base material, and it is possible to perform high-speed peeling. It has become possible to control the contamination of the paper.

Hereinafter, embodiments of the present invention will be described.
In the present specification, a reactive compound (C) having a water-dispersible polymer (A) having a hydroxyl group and a carbonyl group and not having a carboxyl group and a functional group capable of reacting with at least one of the hydroxyl group and the carbonyl group. ), (A1) an ethylenically unsaturated compound having an alkyl group having 4 to 24 carbon atoms, (a2) an ethylenically unsaturated compound having a hydroxyl group, (a3) an ethylenically unsaturated compound having a carbonyl group, and (a4). Other ethylenically unsaturated compounds having no aromatic ring are water-dispersible polymer (A), reactive compound (C), ethylenically unsaturated compound (a1), ethylenically unsaturated compound (a2), and ethylene, respectively. It may be abbreviated as a sex unsaturated compound (a3) and an ethylenically unsaturated compound (a4).

Further, the ethylenically unsaturated compound (a) is a tylene unsaturated compound having no carboxyl group and an aromatic ring.
Further, the "carbonyl group" in the present specification does not include a carbon-oxygen double bond directly bonded to a carbon-carbon double bond represented by a (meth) acryloyl group or the like. Further, although the carbonyl group is derived from an acyl group, carbon-oxygen double bonds contained in a carboxyl group, an acid anhydride group (-C (= O) OC (= O)-), an amide group and an ester group are also available. Not included.

In addition, when it is described as "(meth) acrylic", "(meth) acryloyl", "(meth) acrylic acid", "(meth) acrylate", "(meth) acryloyloxy", and "(meth) allyl". Unless otherwise specified, "acrylic or methacrylic", "acryloyl or methacrylic acid", "acrylic acid or methacrylic acid", "acrylate or methacrylate", "acryloyloxy or methacryloyloxy", and "allyl or methacrylic acid", respectively. ".

≪Water-based pressure-sensitive adhesive≫
First, the water-based pressure-sensitive adhesive will be described.
The aqueous pressure-sensitive adhesive of the present invention has a reactivity having a water-dispersible polymer (A) having a hydroxyl group and a carbonyl group and having no carboxyl group, and a functional group capable of reacting with at least one of the hydroxyl group and the carbonyl group. The water-dispersible polymer (A) containing the compound (C) is a copolymer of a mixture containing the following ethylenically unsaturated compounds (a1) to (a3), and the water-dispersible polymer (A). ) Contains 0.01 to 10 parts by mass of the reactive compound (C) with respect to 100 parts by mass. Further, the water-based pressure-sensitive adhesive of the present invention does not contain a compound having an aromatic ring.
(A1) Ethylene unsaturated compound having an alkyl group having 4 to 24 carbon atoms (a2) Ethylene unsaturated compound having a hydroxyl group (a3) Ethylene unsaturated compound having a carbonyl group

As described above, by using a water-dispersible polymer having no carboxyl group and not containing a compound having an aromatic ring, a re-peelable adhesive label having good adhesiveness and re-peelability to various adherends can be used. It has become possible to manufacture.
Hereinafter, each component constituting the water-based pressure-sensitive adhesive will be specifically described.

<Water-dispersible polymer (A)>
The water-dispersible polymer (A) is an water-dispersible polymer having a hydroxyl group and a carbonyl group and not having a carboxyl group, and (a1) an ethylenically unsaturated compound having an alkyl group having 4 to 24 carbon atoms. , (A2) an ethylenically unsaturated compound having a hydroxyl group, and (a3) a copolymer of a mixture of an ethylenically unsaturated compound having a carbonyl group.
The water-dispersible polymer (A) may further contain, if necessary, another ethylenically unsaturated compound (a4) having no carboxyl group and no aromatic ring, or a reactive surfactant (B). It is obtained by emulsion polymerization of a mixture of these monomers.
That is, the water-dispersible polymer (A) is a mixture of an ethylenically unsaturated compound (a) having no carboxyl group and an aromatic ring, and a monomer containing a reactive surfactant (B), if necessary. The ethylenically unsaturated compound (a) is obtained by polymerizing (a1) an ethylenically unsaturated compound having an alkyl group having 4 to 24 carbon atoms, (a2) an ethylenically unsaturated compound having a hydroxyl group, and (a2). a3) It is classified into an ethylenically unsaturated compound having a carbonyl group and another ethylenically unsaturated compound (a4) having no carboxyl group and an aromatic ring.
Since the water-dispersible polymer (A) does not have an aromatic ring, it is possible to maintain flexibility and curved adhesiveness, and since it does not have a carboxyl group, it adheres even when neutral paper is used as the surface substrate. It can make it possible to maintain power.

<< Ethylene unsaturated compound (a1) >>
The ethylenically unsaturated compound (a1) is an ethylenically unsaturated compound having an ethylenically unsaturated double bond group and an alkyl group having 4 to 24 carbon atoms in the molecule. It does not have an aromatic ring. The alkyl group having 4 to 24 carbon atoms is a linear or branched alkyl group having 4 to 24 carbon atoms. Having an alkyl group having 4 to 24 carbon atoms makes it possible to control the flexibility and appropriate adhesiveness of the coating film.
However, the compound (a1) is a compound other than the compound (a2) described later and the compound (a3) described later.
That is, in the present specification, even if it has an alkyl group having 4 to 24 carbon atoms, it is a compound (a2) when it has a hydroxyl group, and it is a compound (a3) when it has a carbonyl group.

Examples of the compound (a1) include n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, pentyl acrylate, isoamyl acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, and (meth). 2-Ethylhexyl acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 3,4-dimethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, (meth) ) 3,4-dimethylheptyl acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, (meth) ) Isostearyl acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, tetracosyl (meth) acrylate and other (meth) acrylic acid alkyl esters;

For example, alkyl vinyl ethers such as butyl vinyl ether, hexyl vinyl ether, 2-ethylhexyl vinyl ether, octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, lauryl vinyl ether, stearyl vinyl ether;

For example, butyl (meth) allyl ether, hexyl (meth) allyl ether, 2-ethylhexyl (meth) allyl ether, octyl (meth) allyl ether, nonyl (meth) allyl ether, decyl (meth) allyl ether, lauryl (meth). Examples thereof include alkyl (meth) allyl ethers such as allyl ether and stearyl (meth) allyl ether, but the present invention is not particularly limited thereto. These may be used alone or in combination of two or more, but from the viewpoint of adhesiveness and flexibility, a (meth) acrylic acid ester having an alkyl group having 8 to 18 carbon atoms. Is preferable.

<< Ethylene unsaturated compound (a2) >>
The ethylenically unsaturated compound (a2) is an ethylenically unsaturated compound having a hydroxyl group. That is, the compound (a2) is a compound having a hydroxyl group and an ethylenically unsaturated double bond group in its structure and not having an aromatic ring. Even if it has an alkyl group having 4 to 24 carbon atoms, if it has a hydroxyl group, it corresponds to the ethylenically unsaturated compound (a2).
By using the compound (a2) as a part of the constituent monomer, the compound (a1), the compound (a3), or the compound (a4) described later, which is a monomer unit constituting the water-dispersible polymer (A), is used. ) May be easier to improve the efficiency of the copolymerization reaction with). In addition, the viscosity of the water-dispersible polymer (A) can be controlled, and when the reactive compound (C) described later is blended, it reacts with the hydroxyl group and / or the carbonyl group contained in the reactive compound (C). Since the cross-linking reaction with the obtained reactive functional group proceeds and the cohesive force of the coated coating film can be expected to be improved, when it is used for removability, not only the heat resistance and the moisture heat resistance are excellent, but also it is sufficient. It becomes easy to impart processability.

Examples of the compound (a2) include 2-hydroxyethyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl (meth) acrylate. 1-Hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, ( 8-Hydroxyoctyl acrylate, cyclohexanedimethanol mono (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, ethyl-α- (meth) acrylate Fatty acid esters such as hydroxymethyl), monofunctional (meth) acrylic acid glycerol, or (meth) acrylic acid glycidyl lauric acid ester, (meth) acrylic acid glycidyl oleic acid ester, (meth) acrylic acid glycidyl stearate ester. ) Acrylic acid ester or 2- (acryloyloxy) ethyl 6-hydroxyhexanonate, etc., which has a hydroxyl group at the terminal obtained by ring-opening addition of ε-caprolactone to the hydroxyl group-containing ethylenically unsaturated compound. A hydroxyl group-containing fat such as an alkylene oxide-added (meth) acrylic acid ester obtained by repeatedly adding an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to the (meth) acrylic acid ester or the hydroxyl group-containing ethylenically unsaturated compound. Group (meth) acrylic acid esters;

For example, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyhexyl vinyl ether, hydroxyoctyl vinyl ether, hydroxydecyl vinyl ether, hydroxydodecyl vinyl ether, hydroxyoctadecyl vinyl ether, glyceryl vinyl ether, triethylene glycol monovinyl ether, tetraethylene glycol monovinyl ether, tri. Hydroxyl group-containing aliphatic vinyl ethers such as methylolpropane monovinyl ether, pentaerythritol monovinyl ether, or alkylene oxide-added vinyl ether having a hydroxyl group at the terminal to which alkylene oxides such as ethylene oxide and propylene oxide are repeatedly added;

For example, (meth) allyl alcohol, isopropenyl alcohol, dimethyl (meth) allyl alcohol, hydroxyethyl (meth) allyl ether, hydroxypropyl (meth) allyl ether, hydroxybutyl (meth) allyl ether, hydroxyhexyl (meth) allyl ether. , Hydroxyoctyl (meth) allyl ether, hydroxydecyl (meth) allyl ether, hydroxydodecyl (meth) allyl ether, hydroxyoctadecyl (meth) allyl ether, glyceryl (meth) allyl ether, or alkylene oxides such as ethylene oxide and propylene oxide. Lipid group (meth) allyl alcohols or (meth) allyl ethers containing hydroxyl groups such as alkylene oxide addition system (meth) allyl ether having a hydroxyl group at the terminal to which the above is repeatedly added;

For example, it contains hydroxyl groups such as N-hydroxyethyl (meth) acrylamide, N-hydroxypropyl (meth) acrylamide, N-hydroxybutyl (meth) acrylamide, N-hydroxyhexyl (meth) acrylamide, and N-hydroxyoctyl (meth) acrylamide. (Meta) acrylamides and the like, but are not particularly limited thereto. These may be used alone or in combination of two or more.

Examples of the compound (a2) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. from the viewpoint of improving the adhesion to the substrate. Opening ε-caprolactone against hydroxyl group-containing ethylenically unsaturated compounds such as fatty acid ester-based (meth) acrylic acid esters with 2 to 10 carbon atoms and hydroxyl-containing ethylenically unsaturated compounds with 1 to 2 mol of ε-caprolactone added (meth) acrylate. A hydroxyl group-containing aliphatic vinyl ether such as a (meth) acrylic acid ester having a hydroxyl group at the terminal of 2 to 10 carbon atoms and a hydroxyethyl vinyl ether obtained by ring addition, and a hydroxyl group-containing (meth) such as N-hydroxyethyl acrylamide. Esterically unsaturated compounds having 2 to 10 carbon atoms such as acrylamide are preferable.

<< Ethylene unsaturated compound (a3) >>
The ethylenically unsaturated compound (a3) is an ethylenically unsaturated compound having a carbonyl group and does not have an aromatic ring. However, the compound (a3) is a compound other than the compound (a2).
Even if it has an alkyl group having 4 to 24 carbon atoms, if it has a carbonyl group, it corresponds to the ethylenically unsaturated compound (a3).
Further, among the ethylenically unsaturated compounds, the carbon-oxygen double bond directly bonded to the carbon-carbon double bond represented by the (meth) acryloyl group is not included in the above-mentioned "carbonyl group". .. Further, although the carbonyl group is derived from an acyl group, carbon-oxygen double bonds contained in a carboxyl group, an acid anhydride group (-C (= O) OC (= O)-), an amide group and an ester group are also available. It shall not be included in the above "carbonyl group".

Examples of the ethylenically unsaturated compound (a3) include 2-oxobutanoylethyl (meth) acrylate, 2-oxobutanoylpropyl (meth) acrylate, and 2-oxobutanoylbutyl (meth) acrylate. 2-oxobutanoylhexyl acrylate, (meth) 2-oxobutanoyloctyl acrylate, 2-oxobutanoyldecyl (meth) acrylate, 2-oxobutanoyldodecyl (meth) acrylate, (meth) Acrylic acid 3-oxobutanoylethyl, (meth) acrylate 3-oxobutanoylpropyl, (meth) acrylate 3-oxobutanoylbutyl, (meth) acrylate 3-oxobutanoylhexyl, (meth) acrylic acid 3-oxobutanoyloctyl, (meth) acrylate 3-oxobutanoyldecyl, (meth) acrylate 3-oxobutanoyldodecyl, (meth) acrylate 4-cyanooxobutanoylethyl, (meth) acrylate 4 -Cyanooxobutanoylpropyl, 4-cyanooxobutanoylbutyl (meth) acrylate, 4-cyanooxobutanoylhexyl (meth) acrylate, 4-cyanooxobutanoyloctyl (meth) acrylate, (meth) acrylic Acid 2,3-di (oxobutanoyl) propyl, (meth) acrylic acid 2,3-di (oxobutanoyl) butyl, (meth) acrylic acid 2,3-di (oxobutanoyl) hexyl, (meth) Acrylic acid 2,3-di (oxobutanoyl) octyl and other aliphatic (meth) acrylic acid esters having two carbonyl groups;

For example, N- (2-oxobutanoylethyl) (meth) acrylamide, N- (2-oxobutanoylpropyl) (meth) acrylamide, N- (2-oxobutanoylbutyl) (meth) acrylamide, N- ( It has carbonyl groups such as 2-oxobutanoylhexyl) (meth) acrylamide, N- (2-oxobutanoyloctyl) (meth) acrylamide, and N- (1,1-dimethyl-3-oxobutyl) (meth) acrylamide. Examples include, but are not limited to, (meth) acrylamides. These may be used alone or in combination of two or more.

As described above, the ethylenically unsaturated compound (a3) can be introduced into the water-dispersible polymer (A) by using it as a monomer unit constituting the water-dispersible polymer (A). .. By having a carbonyl group in this way, a crosslinked structure can be formed by a coordinate bond of a metal ion contained in a metal chelate which is a reactive compound (C), or an active hydrogen such as an amino group, an imino group or a hydrazino group can be formed. It is possible to form a crosslinked structure by interaction with one or more substituents selected from the group consisting of nitrogen-containing substituents having a Michael addition reaction or the like. Therefore, using the water-based pressure-sensitive adhesive of the present invention containing the water-dispersible polymer (A) and the reactive compound (C), the coated adhesive sheet is attached to a substrate described later. Even after long-term exposure under heating and humidifying heat conditions, the occurrence of deterioration phenomena such as foaming, floating and peeling is significantly suppressed, durability such as heat resistance and moisture heat resistance is significantly improved, and an adhesive sheet is adhered. When peeled off from the body, there is an advantage that the surface of the adherend can be prevented from being contaminated with the adherend such as cloudiness and adhesive residue.

Among the above-mentioned ethylenically unsaturated compounds (a3), 2-oxobutanoylethyl acrylate, considering the ease of forming a coordination bond, the Michael addition reactivity, the price, and the industrially available point, An aliphatic (meth) acrylic acid ester having two carbonyl groups such as 2-oxobutanoylethyl methacrylate, and one carbonyl group such as N- (1,1-dimethyl-3-oxobutyl) acrylamide. Acrylic (meth) acrylamides are particularly preferred.

<< Ethylene unsaturated compound (a4) >>
The ethylenically unsaturated compound (a4) does not have a carboxyl group and an aromatic ring other than the ethylenically unsaturated compound (a1), the ethylenically unsaturated compound (a2), and the ethylenically unsaturated compound (a3). It is an ethylenically unsaturated compound. However, the case of the reactive surfactant (B) described later is excluded.
By using the ethylenically unsaturated compound (a4) as a part of the constituent monomer as needed, the ethylenically unsaturated compound (a1) which is a monomer constituting the water-dispersible polymer (A) is used. ), The ethylenically unsaturated compound (a2), or the ethylenically unsaturated compound (a3) may be facilitated to improve the efficiency of the copolymerization reaction. In addition, the viscosity of the water-dispersible polymer (A) can be controlled, and it becomes easy to improve the workability of the water-dispersible polymer (A) at the time of emulsification, as well as good adhesive strength and various resistances. , And various physical properties such as flexibility may be appropriately controlled.

Examples of the ethylenically unsaturated compound (a4) include (meth) acrylic acid alkyl esters such as methyl (meth) acrylate and (meth) ethyl acrylate; vinyl esters such as vinyl acetate and vinyl propionate; ( Acrylamides such as meth) acrylamide and dimethyl (meth) acrylamide; vinyl ethers such as ethyl vinyl ether and propyl vinyl ether; (meth) acrylic acid such as 2-methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate. Alkylene esters; (meth) methoxydiethylene glycol acrylate, (meth) methoxypolyoxyethylene acrylate (number of moles added with EO: 3 to 20), (meth) methoxypolyoxypropylene acrylate (number of moles added with PO: 2 to 20) ) And the like (meth) acrylic acid esters; other examples include (meth) acrylonitrile, (meth) perfluoromethyl acrylate, 3- (meth) acryloyloxypropylmethyldimethoxysilane, and the like. Only seeds may be used, or a plurality of seeds may be used in combination, but they do not have an aromatic ring from the viewpoint of removability, adhesion to a substrate, and maintenance of curved adhesiveness.

<< Production method of water-dispersible polymer (A) >>
The water-dispersible polymer (A) includes the ethylenically unsaturated compound (a1), the ethylenically unsaturated compound (a2) and the ethylenically unsaturated compound (a3), and if necessary, the ethylenically unsaturated compound (a4). ) Can be obtained by copolymerizing. Among the above-mentioned monomers, a compound having a (meth) acryloyl group is preferable from the viewpoint of reactivity. In various ethylenically unsaturated compounds, thus, control of the viscosity and emulsifying property of the water-dispersible polymer (A), particle size and storage stability, adhesiveness and removability of the adhesive sheet, or durability. , The ethylenically unsaturated compound (a1), the ethylenically unsaturated compound (a2), the ethylenically unsaturated compound (a3) and, if necessary, the ethylenically unsaturated compound (a4), taking into consideration the coating suitability and the like. ) Can be selected.

The water-dispersible polymer (A) is synthesized by a method such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization by synthesizing a mixture of various ethylenically unsaturated compounds as described above according to a conventional method. The polymerization method and reaction operation are not particularly limited, but emulsion polymerization is preferable. In the case of emulsion polymerization, a monomer mixture of various ethylenically unsaturated compounds as described above, a polymerization initiator, and a surfactant are used as main components, and water is used as a medium for polymerization.
The usual emulsification polymerization method is carried out by emulsifying a monomer mixture of various ethylenically unsaturated compounds in water with a surfactant and adding a water-soluble polymerization initiator to this system (also referred to as a pre-emulsification method). Since the polymerization proceeds in micelles formed by the surfactant, it is possible to produce a resin having a high molecular weight that cannot be obtained by other polymerization methods. Moreover, since no organic solvent is used, a high polymerization reaction rate can be expected, and the particle size and viscosity can be controlled.

The polymerization initiator used for emulsion polymerization is usually 0.001 to 5.0 parts by mass with respect to a total of 100 parts by mass of a mixture of various ethylenically unsaturated compounds as described above, but is particularly limited. Instead, it can be appropriately selected from a water-soluble polymerization initiator and an oil-soluble polymerization initiator.

Examples of the water-soluble polymerization initiator include potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, and ammonium (amine) salts of 4,4'-azobis-4-cyanovaleric acid.

Examples of the oil-soluble polymerization initiator include alkylpaoxide, t-butylhydropaoxide, cumenehydropaoxide, p-methanehydropaoxide, lauroylpaoxide, 3,5,5-trimethylhexanoylpaoxide, and octanoylpaoxide. , T-butylcumylperoxide, benzoylpaoxide, dichlorbenzoylpaoxide, dicumylperoxide, dit-butylpaoxide, 1,1-bis (t-butylpaoxy) -3,3,5-trimethyl Cyclohexane, 3,3,5-trimethylcyclohexanone compound, methylcyclohexanone compound, di-isobutylpa-oxydica-bonate, di-2-ethylhexylpa-oxydica-bonate, t-butylpa-oxyisobuty Organic peroxides such as rates, 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, 2,2'-azobis (2,4-dimethylvaleronitrile), 2 , 2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2-methylamide oxime) dihydrochloride, 2,2'-azobis (2-methylbutanamide oxime) dihydrochloride tetrahydrate, 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] -propionamide}, 2,2'-azobis [2-methyl-N- (2-methyl-N-) Hydroxyethyl) -propionamide] and other azo compounds can be mentioned.

Further, as the polymerization initiator, a redox initiator in which an oxidizing agent and a reducing agent are used in combination can also be preferably used.
Examples of the oxidizing agent include ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide and the like.
Examples of the reducing agent include sodium sulfite, sodium acid sulfite, sodium formaldehyde sulfoxylate dihydrate (also known as longalit), ascorbic acid and the like.

In addition, a buffer can be used to adjust the pH as needed during emulsion polymerization. The buffering agent is not particularly limited as long as it has a pH buffering action of the reaction solution of emulsion polymerization. Examples of the buffering agent include sodium hydrogen carbonate, potassium hydrogen carbonate, monosodium phosphate, monopotassium phosphate, disodium phosphate, trisodium phosphate, sodium acetate, ammonium acetate, sodium formate, ammonium formate, and tricitrate. Examples include sodium.
The buffer is preferably used in an amount of less than 5 parts by mass, more preferably less than 3 parts by mass, based on a total of 100 parts by mass of the monomer mixture of various ethylenically unsaturated compounds as described above.

Further, at the time of emulsion polymerization, it is also possible to appropriately adjust the molecular weight of the water-dispersible polymer (A) by using a chain transfer agent. As the chain transfer agent, for example, a thiol-based compound such as a mercaptan-based compound, a thioglycol-based compound, or β-mercaptopropionic acid may be used.

The polymerization conditions for the polymerization reaction of the water-dispersible polymer (A) may be appropriately set according to the polymerization method, and are not particularly limited. The polymerization temperature is preferably 20 to 150 ° C, more preferably 40 to 120 ° C. The reaction time may be appropriately set so that the polymerization reaction of each component of the ethylenically unsaturated compound is completed.

The content of each compound was 85 to 99.98% by mass of the ethylenically unsaturated compound (a1) in 100% by mass of the mixture of the ethylenically unsaturated compounds constituting the water-dispersible polymer (A), and the ethylenically unsaturated compound. The saturated compound (a2) is preferably 0.01 to 10% by mass, and the ethylenically unsaturated compound (a3) is preferably 0.01 to 5% by mass, and the ethylenically unsaturated compound (a1) is 92 to 99.85% by mass. , The ethylenically unsaturated compound (a2) 0.1 to 5% by mass, and the ethylenically unsaturated compound (a3) 0.05 to 3% by mass are more preferable.

Further, when the ethylenically unsaturated compound (a4) is contained, if necessary, the ethylenically unsaturated compound (a1) is contained in 100% by mass of the mixture of the ethylenically unsaturated compounds constituting the water-dispersible polymer (A). ) 45-99.97% by mass, ethylenically unsaturated compound (a2) 0.01-10% by mass, ethylenically unsaturated compound (a3) 0.01-5% by mass, and ethylenically unsaturated compound (a4). It is preferably 0.01 to 40% by mass, preferably the ethylenically unsaturated compound (a1) 62 to 99.84% by mass, the ethylenically unsaturated compound (a2) 0.1 to 5% by mass, and the ethylenically unsaturated compound. It is more preferably in the range of (a3) 0.05 to 3% by mass and the ethylenically unsaturated compound (a4) 0.01 to 30% by mass.

When the content of each ethylenically unsaturated compound is within the above range, the polar sites associated with the hydroxyl groups and carbonyl groups in the adhesive layer are oriented toward the surface of the adherend, and the surface polarity of the adhesive layer is changed. In addition, it has flexibility because it does not have an aromatic ring, and while exhibiting appropriate adhesiveness, when peeled off, contamination of the adherend such as cloudiness and adhesive residue is suppressed, and the surface base material Even when neutral paper or glossy paper containing calcium carbonate is used, since it does not have a carboxyl group, the adhesiveness and curved surface adhesiveness do not deteriorate even after long-term storage. Therefore, the water-dispersible copolymer (A) Appropriately control various physical properties such as glass transition temperature (hereinafter, may be abbreviated as "Tg"), adhesive strength, curved adhesiveness, various resistances, flexibility, compatibility, emulsification and removability. Is possible.

The water-dispersible polymer (A) has a glass transition point (Tg) of -80 to 10 ° C., so that the water-dispersible polymer (A) can sufficiently exhibit good adhesiveness and removability. It is preferable to select the composition ratio of each monomer which is a constituent component of the water-dispersible polymer so that the temperature is preferably −70 to −10 ° C. When Tg is within the above range, not only the emulsification of the water-dispersible polymer (A) becomes easy, but also the adhesion obtained from the water-based pressure-sensitive adhesive containing the approximately water-dispersible polymer (A). It is possible to maintain processability such as punching and cutting while maintaining the flexibility of the sheet. The Tg of the water-dispersible polymer (A) in the present invention was determined by using a differential scanning calorimeter (DSC) described later. Details of the method for measuring the glass transition temperature (Tg) are described in Examples.

<Reactive surfactant (B)>
Next, the reactive surfactant (B) will be described.
The water-dispersible polymer (A) can be obtained by emulsion polymerization of a mixture of the above monomers. The surfactant used in the emulsifying polymerization is preferably appropriately selected from anionic surfactants and / or nonionic surfactants, and among them, it is effective in suppressing adherent contamination derived from the surfactants. Reactive surfactants are preferably used, and anionic reactive surfactants are particularly preferably used.
The reactive surfactant (B) has a reactive group copolymerizable with the ethylenically unsaturated compound (a) constituting the water-dispersible polymer (A) and does not have an aromatic ring. Is.
By containing the reactive surfactant (B), when the adhesive sheet is peeled off from the adherend, it becomes possible to prevent fogging and adhesive residue derived from the surfactant, and the re-peelability is improved.

The reactive surfactant (B) is not particularly limited, and various known reactive surfactants of anionic and / or nonionic properties can be used, but at least an anionic reactive surfactant is essentially contained. It is preferable to do so. It is also possible to use a nonionic surfactant in combination. The content thereof is preferably 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the water-dispersible polymer (A). When the reactive surfactant (B) is contained in the above range, the water resistance and moisture heat resistance of the adhesive layer are not impaired, good removability is exhibited, and the storage stability of the water-based pressure-sensitive adhesive is improved. It will be possible to secure it.

When the reactive surfactant (B) is used during the emulsifying polymerization in the production of the water-dispersible polymer (A), the reactive surfactant (B) becomes a constituent unit of the polymer (A). The content of each compound is 75 to 99.88% by mass of the ethylenically unsaturated compound (a1) and the ethylenically unsaturated compound (a2) in 100% by mass of the mixture of the compounds constituting the water-dispersible polymer (A). ) 0.01 to 10% by mass, preferably 0.01 to 5% by mass of the ethylenically unsaturated compound (a3), and 0.1 to 10% by mass of the reactive surfactant (B), preferably ethylenically unsaturated. Saturated compound (a1) 87-99.35% by mass, ethylenically unsaturated compound (a2) 0.1-5% by mass, ethylenically unsaturated compound (a3) 0.05-3% by mass, and reactive surface activity The agent (B) is more preferably in the range of 0.5 to 5% by mass.

When the ethylenically unsaturated compound (a4) is contained as a constituent unit, if necessary, the ethylenically unsaturated compound (a1) is contained in 100% by mass of the mixture of the compounds constituting the water-dispersible polymer (A). ) 35-99.87% by mass, ethylenically unsaturated compound (a2) 0.01-10% by mass, ethylenically unsaturated compound (a3) 0.01-5% by mass, ethylenically unsaturated compound (a4) 00 It is preferably 0.01 to 40% by mass, and the reactive surfactant (B) is preferably 0.1 to 10% by mass, and the ethylenically unsaturated compound (a1) 57 to 99.34% by mass, an ethylenically unsaturated compound. (A2) 0.1 to 5% by mass, ethylenically unsaturated compound (a3) 0.05 to 3% by mass, ethylenically unsaturated compound (a4) 0.01 to 30% by mass, and reactive surfactant ( B) More preferably, it is in the range of 0.5 to 5% by mass.

Examples of the anionic reactive surfactant include polyoxyethylene alkylpropenyl ether sulfate ammonium, polyoxyethylene styrenated propenylphenyl ether sulfate ammonium, and α-sulfo-ω- {1- (nonylphenoxy) methyl-. 2- (2-Propenyloxy) ethoxy} -poly (oxy-1,2-ethandyl) ammonium, polycyclic phenyl ether methacrylate ester ammonium, polyoxyethylene polycyclic phenyl ether sulfate ester, 2-dimethylaminoethyl methacrylate, etc. Polyoxyethylene alkyl alkenyl phenyl ether sulfate ester salt;

For example, α-sulfo-ω- {1-alkoxymethyl-2- (2-propenyloxy) ethoxy} -poly (oxy-1,2-ethandyl) ammonium, polyoxyethylene-1- (allyloxymethyl) alkyl ether. Polyoxyethylene alkyl alkenyl ether sulfate ester salts such as ammonium sulfate, polyoxyalkylene alkyl ether ammonium sulfate, methacryloyloxypolyoxypropylene sulfate sodium;

Examples thereof include succinic acid and phosphoric acid-based surfactants such as alkyl sulfosuccinic acid alkenyl ether, alkyl alkenyl succinic acid ester, and alkyl alkenyl phosphoric acid ester. These can be used alone or in combination of two or more.

Examples of the nonionic reactive surfactant that can be used in combination include polyoxyethylene alkylpropenylphenyl ether, allyloxymethylalkoxyethyl hydroxypolyoxyethylene, polyoxyalkylene alkenyl ether, alkoxypolyethylene glycol methacrylate, and alkoxypolyethylene glycol maleine. Examples thereof include acid esters and polyalkylene glycol mono (meth) acrylates. These can be used alone or in combination of two or more.

The reactive surfactant (B) preferably contains an anionic reactive surfactant as described above, and further has no aromatic ring, in terms of adhesion to the substrate which is the support. It is preferable to contain an ethylene alkyl alkenyl ether sulfate ester salt.

<Reactive compound (C)>
The reactive compound (C) is a reactive compound having a functional group capable of reacting with at least one of a hydroxyl group and a carbonyl group of the water-dispersible polymer (A).
The reactive compound (C) can be used as a cross-linking agent for the water-dispersible polymer for cross-linking between the particles of the water-dispersible polymer (A). The compound (C) is a compound that can react with the water-dispersible polymer (A). Further, the case of the reactive surfactant (B) is excluded.
The cross-linking agent for the water-dispersible polymer is essentially non-reactive with respect to the water-dispersion particles in the water-dispersible liquid, but when water is removed from the water-dispersible liquid by drying, the water-dispersible polymer is obtained. A chemical reaction occurs between the functional group contained in the water-dispersible polymer and the functional group contained in the cross-linking agent for the water-dispersible polymer, and a covalent bond is formed between the particles. This reaction proceeds at high speed under ambient conditions, and the aqueous dispersion particles can be regarded as cross-linked, that is, externally cross-linked (also known as external cross-linking). That is, the reactive compound (C) in the present invention is a compound that forms an interparticle crosslink between particles in a short time when water is removed. By performing interparticle cross-linking using the reactive compound (C) in this way, it is possible to prevent the transfer from the adhesive layer to the adherend when the adhesive sheet is peeled off, and adhesive residue and fogging can be prevented. It is less likely to occur and the removability is improved.

The functional group of the reactive compound (C) that can react with at least one of the hydroxyl group and the carbonyl group includes a divalent or higher metal ion forming a coordination bond, an amino group, an imino group, a hydrazino group, and an active hydrogen. Included is at least one of one or more substituents selected from the group consisting of nitrogen-containing heterocyclic groups having.

Examples of the compound having a divalent or higher metal ion forming a coordination bond include a metal chelate compound (c1) (hereinafter, may be abbreviated as compound (c1)), which has adhesiveness after a crosslinking reaction and punching. It is possible to improve workability, heat resistance, and moisture heat resistance.

The metal chelate compound (c1) is a compound in which a ligand having two or more loci forms a complex so as to sandwich a metal ion, and is composed of a ring containing a central metal and a coordination atom.
Examples of the metal chelate compound (c1) include alkaline earth metals such as magnesium, calcium, strontium and barium, aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium and boron. , Cobalt, manganese, selenium, chromium, ruthenium, gallium, cadmium, neodium and other transition metals, and compounds in which ligands with multiple coordination constituencies are coordinated.

Examples of the ligand having a plurality of coordination constellations include β-diketone, β-ketoester, polyhydric alcohol, alkanolamine and oxycarboxylic acid, but β-diketone and β-ketoester having no carboxyl group. Polyhydric alcohols or alkanolamines are preferable, and β-diketone or β-ketoester is a ligand having a weak ligand field, and is therefore more preferable in terms of cross-linking reactivity with the water-dispersible polymer (A). These include, but are not limited to, compounds coordinated with at least one kind. These can be used alone or in combination of two or more.

The β-diketone is not particularly limited as long as it is coordinated as a chelating agent, and for example, 2,4-pentandione, 2,4-hexanedione, 2,4-heptandione, and thenoyltrifluoroacetone. , 1,3-Cyclohexanedione and the like, but are not particularly limited thereto.

The β-ketoester is not particularly limited, but for example, methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate, methylpivaloyl acetate, methylisobutyroyl acetate, methyl caproyl acetate, methyl lauroyl acetate and the like. However, it is not particularly limited to these.

The polyhydric alcohol is not particularly limited, but for example, 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 2,3-butanediol, 2 , 3-Pentanediol, glycerin, diethylene glycol, hexylene glycol and the like are not particularly limited thereto.

The alkanolamine is not particularly limited, but is N, N-dimethylethanolamine, N, N-diethylethanolamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N. -Ethylethanolamine, N-n-butylethanolamine, Nn-butyldiethanolamine, N-tert-butylethanolamine, Ntert-butyldiethanolamine, triethanolamine, diethanolamine, monoethanolamine Etc. are not particularly limited to these.

The metal constituting the metal chelate compound (c1) is preferably magnesium, titanium, zirconium, aluminum, and more preferably at least one of magnesium and zirconium or a mixture thereof. Since complex formation is likely to occur due to charge transfer interaction with the hydroxyl group or carbonyl group contained in the sex polymer (A), a cross-linking reaction easily occurs, and in addition to removability, appropriate adhesive strength and durability can be maintained. It is preferable because it is possible.
That is, preferable examples of the metal chelate compound (c1) include magnesium-based chelate compounds and zirconium-based metal chelate compounds. These can be used alone or in combination of two or more.

Specific examples of the magnesium-based chelate compound include, for example, dinormal butylmagnesium, magnesium octylene glycolate, magnesium diacetylacetonate, bis (hexafluoroacetylacetonato) magnesium, and diaquabis (2,4-pentandionato) magnesium. Examples thereof include, but are not limited to, magnesium di (s-butoxide) acetoacetate, magnesium trifluoroacetyl acetone, magnesium acetoacetate ethyl, magnesium diethanol aminate and the like.

Specific examples of the zirconium-based chelate compound include zirconium normal propyrate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, and zirconium acetylacetonate bisethylacetoacetate. It is not particularly limited to these.

Among these metal chelate compounds (c1), the handling safety, the reactivity with the water-dispersible polymer (A), the viewpoint of coloring, and the heat resistance, moisture heat resistance, and removability of the adhesive layer are further improved. In terms of surface, it is preferable to use magnesium diacetylacetonate or zirconium tetraacetylacetonate containing the above β-diketone as a ligand.

Among the functional groups capable of reacting with the hydroxyl group and the carbonyl group of the reactive compound (C), the functional groups capable of reacting with the carbonyl group include an amino group, an imino group, a hydrazino group, and a nitrogen-containing heterocycle having an active hydrogen. A compound (c2) having two or more functional groups in the molecule capable of reacting with the carbonyl group of the water-dispersible polymer (A), including one or more substituents selected from the group consisting of groups (hereinafter referred to as compound). (C2) may be abbreviated) is preferably used. In particular, a hydrazine derivative having a hydrazino group has a weak reaction activity with respect to a hydroxyl group, but has a high reaction activity with respect to a carbonyl group, and is excellent in adhesion after a crosslinking reaction and adhesion to a substrate described later. Therefore, it is preferably used.

As the hydrazine derivative, any compound having one or more hydrazine groups (-NHNH2) in the molecule can be suitably used without limitation. For example, carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succi acid dihydrazide, glutalic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleate dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, ethylene-1,2-dihydrazide, Dicarboxylic acid dihydrazides such as -1,3-dihydrazine, butylene-1,4-dihydrazine, 1,3-bis (hydradinocarbonoethyl) -5-isopropylhydranthin;

For example, tricarboxylic acid trihydrazides such as citrate trihydrazide, nitriloacetate trihydrazide, 1,8-dihydrazide-4-hydrazidemethyloctane;

Examples thereof include tetracarboxylic acid tetrahydrazides such as pyromellitic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydrazide, ethylenediamine tetraacetate tetrahydrazide, and these may be used alone. Alternatively, a plurality of types may be used in combination, but it is preferable not to have an aromatic ring from the viewpoint of removability, adhesion to the substrate, and maintenance of curved surface adhesiveness. Among these, adipic acid dihydrazide is more preferable in terms of stability and reactivity of the water-dispersible polymer.

As described above, the reactive compound (C) has an amino group and a metal chelate compound (c1) having a divalent or higher metal ion forming a coordination bond as a functional group capable of reacting with at least one of a hydroxyl group and a carbonyl group. , Imino group, hydrazino group, and at least one of the compounds (c2) having one or more substituents selected from the group consisting of a nitrogen-containing heterocyclic group having active hydrogen, and the aqueous pressure-sensitive adhesion of the present invention. The agent preferably contains at least one of compound (c1) and compound (c2), but the inclusion of both compound (c1) and compound (c2) results in adhesive strength, heat resistance, and re-peeling. More preferable in terms of sex.

The reactive compound (C) is preferably contained in an amount of 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and 0.01 to 5 parts by mass with respect to 100 parts by mass of the aqueous dispersible polymer (A). 1 part by mass is more preferable (note that the mass part of the reactive compound (C) is the total amount of the compound (c1) and the compound (c2)). When the reactive compound (C) is in this range, the reactive compound (C) does not precipitate during storage of the aqueous pressure-sensitive adhesive, and the heat resistance and moisture heat resistance are improved by the crosslinking reaction, so that the environment is harsh. The floating, peeling, or foaming of the adhesive layer can be further suppressed, and the re-peelability is further improved.

<Other compounds (F)>
Next, the other compound (F) will be described.
In one embodiment of the water-based pressure-sensitive adhesive of the present invention, the water-dispersible polymer may further contain another compound (F) in addition to the above components as long as the problem can be solved.
The other compound (F) is a compound other than the water-dispersible polymer (A), the reactive surfactant (B) and the reactive compound (C), and the material is stabilized by adding a small amount of components. It is a compound that has the function of improving properties and physical properties. For example, non-reactive surfactants, plasticizers, preservatives, rust inhibitors, freeze-melt stabilizers, colorants, fillers, wetting agents, antioxidants, flame retardants, storage stabilizers, UV absorbers, and thixotropics. Examples thereof include agents, dispersion stabilizers, fluidity-imparting agents, film-forming aids, moisturizing agents, pH adjusting agents, leveling agents, defoaming agents, viscosity adjusting agents, and other additives.

<Water-based pressure-sensitive adhesive>
Next, the water-based pressure-sensitive adhesive will be described.
As described above, the aqueous pressure-sensitive adhesive of the present invention comprises the water-dispersible polymer (A) and the reactive compound (C), as well as the reactive surfactant (B) and other compounds (B), if necessary. It is obtained by coexisting F).
The non-volatile content concentration of the water-based pressure-sensitive adhesive is not particularly limited, but is usually adjusted to about 40 to 70% by mass depending on the usage mode. In addition, if necessary, additional water may be used to adjust the viscosity. Furthermore, the viscosity can be reduced by heating the aqueous pressure sensitive adhesive without the use of additional moisture.
Further, when the adhesive layer is formed by using the water-based pressure-sensitive water-based adhesive of the present invention, the water-dispersible polymer (A) is the main agent from the viewpoint of forming a coating film, so that the water-based pressure-sensitive adhesive is used. The average particle size is not significantly different from the average particle size of the water-dispersible polymer (A) having a non-volatile content concentration of about 55% by mass, and is usually about 0.05 to 10 μm, and most of the particles are uniform as particles of 1 μm or less. It is emulsified and dispersed. The water-based pressure-sensitive adhesive has a white to milky white appearance and has a pH value of about 5 to 11.

When the adhesive layer is formed using the water-based pressure-sensitive adhesive of the present invention, the thickness of the adhesive layer is preferably 0.5 to 100 μm, more preferably 1 to 50 μm. When the film thickness is in the above range, it is possible to obtain a sufficient adhesive force.
Therefore, from the viewpoint of coating film formation and performance, the viscosity of the water-based pressure-sensitive adhesive is in the range of 500 to 30,000 mPa · s when measured with a B-type viscometer at 25 ° C. It is preferably in the range of 1,000 to 15,000 mPa · s, more preferably. When the viscosity is 30,000 mPa · s or less, a thin film of 0.5 to 100 μm can be easily formed on the substrate by coating, and it is also easy to improve the adhesive properties such as tack, adhesive force and holding force. Is. On the other hand, when the viscosity is 1,000 mPa · s or more, it is easy to control the film thickness of the adhesive layer formed from the water-based pressure-sensitive adhesive. In the present embodiment, the film thickness, viscosity, or non-volatile content concentration of the adhesive layer is set according to the use of the laminated body.

Further, in order to show good removability, the water-based pressure-sensitive adhesive preferably has a gel fraction (Gel%) of 85% or more with respect to ethyl acetate in the dry coating film, and is 90% or more and less than 95%. It is more preferable to have. When Gel% is in this range, when the adhesive sheet formed of the approximately water-based pressure-sensitive adhesive is left in a high-temperature atmosphere, the cohesive force of the adhesive layer is not reduced and the adhesive force is good but adhered. Since the agent layer and the adherend are not excessively adhered to each other, the removability is improved. The details of the method for measuring the gel fraction (Gel%) of the dry coating film with respect to ethyl acetate will be described in Examples.

≪Adhesive sheet≫
Next, the adhesive sheet will be described.
The adhesive sheet (also referred to as an adhesive film) of the present invention includes a base material which is a support described later, and an adhesive layer formed from the above-mentioned water-based pressure-sensitive adhesive. The adhesive layer may be laminated with a sheet-like base material (also referred to as a release liner) whose surface has been further peeled off.
As a method for producing an adhesive sheet, a method of applying a water-based pressure-sensitive adhesive to a base material and then removing water by a method such as heating to form an adhesive layer on the base material, or a release liner. Examples thereof include a method in which a water-based pressure-sensitive adhesive is applied to the peeled surface of the above, dried, and the base materials are bonded to each other.

The method of applying the water-based pressure-sensitive adhesive is not particularly limited. For example, various well-known methods such as Meyer bar, applicator, brush, spray, roller, gravure coater, die coater, kiss coater, lip coater, comma coater, blade coater, knife coater, reverse coater, spin coater, dip coater, etc. Can be applied. Further, the form of thin film coating or thick film coating can also be selected without particular limitation depending on the intended use.

The basic laminated structure of the adhesive sheet is a single-sided adhesive sheet such as a base material / adhesive layer / release liner, or a double-sided adhesive sheet such as a release liner / adhesive layer / base material / adhesive layer / release liner. .. The laminated body laminated on the release liner in this way is called an adhesive sheet. At the time of use, the release liner is peeled off and the adhesive layer is attached to the adherend. In the water-based pressure-sensitive adhesive, not only the adhesive layer has adhesiveness at the moment when the adhesive layer touches the adherend at the time of adhesion, but also an adhesive other than the pressure-sensitive adhesive (hereinafter, simply referred to as an adhesive). ), It is necessary to have a cohesive force for maintaining the sticking state while having a tack and an appropriate hardness without completely solidifying during sticking. The cohesive force largely depends on the molecular weight and the crosslink density. The laminated body laminated in the structure of the base material / adhesive layer / adherend in this way is called a bonded laminated body.

The adhesive sheet using the water-based pressure-sensitive adhesive of the present invention is used for a wide range of applications of various known adhesive products (labels, seals, tapes, stickers, etc.), and the water-based pressure-sensitive adhesive has two or more. An adhesive layer is formed to bond the base materials (one of the base materials is the base base material of the adhesive sheet, and the other of the base materials is the base material to which the base material is attached (referred to as an adherend)). The water-based pressure-sensitive adhesive of the present invention is generally used for various labels such as general paper, kraft paper, metal, glass, plastic, rubber, wood, and painted surfaces, masking tape applications, protective film applications, and concrete. , Cement mortar, various metals, leather, glass, vinyl chloride sheet, decorative paper, plywood panel, building materials used for bonding materials such as gypsum board, ceiling materials, decorative parts, door rims, seat sheets, instrument panels , Dash silencer, center console, pillar trim, rear parcel and other automobile interior materials, and wire binding tape and other wire covering materials.
Among these, the application is not particularly limited, but it can be suitably used for various labels, masking tape applications, protective film applications, and the like.

The base material is a plate or sheet such as paper, cellophane, plastic sheet, rubber, foam, cloth, rubberized cloth, resin impregnated cloth, glass plate, metal plate, wood, optical film such as polarizing plate. Can be mentioned. Further, the base material may be a single material or a laminated body. Further, the base material can be peeled off or antistatic treated on the back surface (opposite surface of the surface to which the adhesive layer is directly bonded). Further, the base material can be coated with a known anchoring agent to improve the adhesion to the adhesive layer.

Of the above base materials, paper is widely used, and printing paper such as cast paper, art paper, and high-quality paper, heat-sensitive paper with a functional layer on these paper, and information paper such as inkjet paper are widely used. Has been done. Conventional paper uses rosin as a sizing agent (to prevent ink bleeding) (also called acid paper), but acid-free paper is paper manufactured in the neutral to weakly alkaline range and is a filler (filler). ) Is mainly used as calcium carbonate, so it is different from acid paper. Acid-free paper is nowadays mainly used for books and materials.
The water-based pressure-sensitive adhesive of the present invention can suppress a decrease in adhesiveness due to deterioration even when such neutral paper or the like is used as a base material, and has high-temperature removability and durability. It is possible to achieve both and suppress contamination by high-speed peeling.

As described above, examples of the peeling liner include those obtained by peeling the surface of a sheet-like substrate such as cellophane, various plastic sheets, paper, and metal foil. Further, the sheet-like base material may be a single layer or a material in a multi-layered state in which a plurality of base materials are laminated.

Hereinafter, specific examples of the present invention will be described together with comparative examples, but the present invention is not limited to the following examples. Further, in the following Examples and Comparative Examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

<Manufacturing of water-dispersible polymer (A)>
(Synthesis Example 1)
The following ethylenically unsaturated compounds, surfactants and ion-exchanged water were charged into the stirring tank of a stirring device equipped with a stirring tank, a stirrer and a thermometer in the following ratios.

[Stirring tank]
2-Ethylhexyl acrylate acrylate (a1) 97.17 parts 2-hydroxyethyl acrylate (a2) 1.26 parts 2-acetoacetoxyethyl methacrylate (a3) 0.58 parts KH10 (reactive surfactant) 0. 99 parts Ion-exchanged water 32.70 parts

The above compounds were mixed while stirring in the stirring tank to obtain a pre-emulsified product. Next, the pre-emulsified product of the above compound, the polymerization initiator and the ion-exchanged water are added to the reaction tank and the dropping device of the polymerization reaction device equipped with the polymerization tank, the stirrer, the thermometer, the reflux condenser, the dropping device and the nitrogen introduction tube. Each was prepared in the following ratio.

[Polymerization tank]
Ion-exchanged water (W) 49.07 parts
[Dripping device]
Pre-emulsified product of the above monomer 132.70 parts Potassium persulfate (polymerization initiator) 0.02 parts

After replacing the air in the polymerization tank with nitrogen gas, the temperature was raised to 80 ° C. while stirring under a nitrogen atmosphere, and 0.01 part of potassium persulfate was added.
After 5 minutes, a mixed solution of the pre-emulsified product of the monomer and potassium persulfate was added dropwise from the dropping device over 3 hours.
While maintaining the reaction temperature at 80 ° C. and further stirring, potassium persulfate was added twice every 0.5 hours by 0.005 parts, and then aged for 2 hours to continue the reaction. Then, the mixture was cooled to 25 ° C. to obtain an aqueous dispersion of the water-dispersible polymer (A) having a non-volatile content concentration of about 55%. At this time, the filterability and the pot stain property were evaluated as productivity according to the method described later, and the results are shown in Table 1-2.
Further, the non-volatile content concentration (NV), solution viscosity (Vis), average particle size (Dm), acid value (AV) hydrogen ion index (pH) and glass transition temperature (Tg) of the obtained aqueous dispersion will be described later. The results were shown in Table 1-2.

(Synthesis Examples 2 to 30)
Aqueous dispersions of water-dispersible polymers were synthesized in the same manner as in Synthesis Example 1, except that the materials and blending amounts shown in Table 1-1 were changed. The numerical values shown in Tables 1-1 and 1-2 represent "parts" unless otherwise specified, and blanks and "-" notations indicate that they are not used or have not been evaluated. ..
Of these, the aqueous dispersions obtained in Synthesis Examples 2, 7, 12, 22, 23 and 28 are aqueous dispersions that are not the water-dispersible polymer (A).
Further, the aqueous dispersions obtained in 1, 3 to 6, 8 to 11, 13 to 21, 24 to 27, 29 and 30 are aqueous dispersions of the aqueous dispersion polymer (A).

The mass described in the column of the polymerization initiator in Table 1-1 is the total mass added in the polymerization tank, the total mass dropped during the dropping, and the post-addition is the total mass added twice after the completion of the dropping. Means. In addition, the surfactant represents the mass in terms of non-volatile content concentration.

<< Evaluation of filterability >>
The aqueous dispersion of the water-dispersible polymer obtained in Synthesis Examples 1 to 30 was filtered through a 180-mesh furnace cloth and evaluated in three stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: Can be filtered quickly and has no residue. Good.
Δ: It takes some time for filtration, and some residue remains to the extent that it does not affect the non-volatile content concentration. Can be used practically.
X: Filtration time is long and there is a considerable amount of residue. The non-volatile content concentration is decreasing. Not practical.

《Evaluation of pot stains》
The state of solid adhesion to the wall of the polymerization tank after the production of the aqueous dispersion of the water-dispersible polymer obtained in Synthesis Examples 1 to 30 and the detergency with water were evaluated in three stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: There is no adhesion and the cleaning property is good. Good.
Δ: There is some adhesion of solid matter, but the detergency is good. Can be used practically.
X: There is a lot of solid matter adhering to it, and it cannot be removed by washing. Not practical.

<< Non-volatile content concentration (NV) >>
About 1 g of the aqueous dispersion of the water-dispersible polymer obtained in Synthesis Examples 1 to 30 is weighed in a metal container, dried in an oven at 150 ° C. for 20 minutes, and the residue is weighed to calculate the residual ratio. The non-volatile content concentration (solid content) was used (unit:%).

<< Liquid Viscosity (Vis) >>
The aqueous dispersions of the water-dispersible polymers obtained in Synthesis Examples 1 to 30 were each subjected to a B-type viscometer (TV-22 manufactured by Toki Sangyo Co., Ltd.) at 25 ° C., rotor Nos. 2-4, rotation speed 0. The viscosity of the liquid (mPa · s) was measured under the conditions of rotation at 5 to 100 rpm for 1 minute.

<< Average particle size (Dm) >>
The average particle size of the water-dispersible polymer obtained in Synthesis Examples 1 to 30 in the aqueous dispersion was measured using "Microtrac" manufactured by Nikkiso Co., Ltd. For the average particle size, a value of 50% of the cumulative percentage was applied.

<< Glass transition temperature (Tg) >>
The glass transition temperature (Tg) of the water-dispersible polymer obtained in Synthesis Examples 1 to 30 was determined by using a robot DSC (differential scanning calorimeter, "RDC220" manufactured by Seiko Instruments) and "SSC5200 Disk Station" (manufactured by Seiko Instruments). ) Was connected and measured. Place about 10 mg of the sample in an aluminum pan, weigh it, set it in a differential scanning calorimeter, hold it at a temperature of 100 ° C for 5 minutes using an aluminum pan of the same type without a sample as a reference, and then use liquid nitrogen. It was rapidly cooled to 120 ° C. Then, the temperature was raised at a heating rate of 10 ° C./min, and the glass transition temperature (Tg, unit: ° C.) was determined from the obtained DSC chart.

<< Hydrogen ion index (pH) >>
The pH of the aqueous dispersion of the water-dispersible polymer obtained in Synthesis Examples 1 to 30 was measured using F-52S manufactured by HORIBA, electrode: model 6377-10D.

<Abbreviations in Table 1-1 and Table 1-2>
-Ethylene unsaturated compound (a1)
BA: butyl acrylate, 2EHA: 2-ethylhexyl acrylate, LMA: lauryl methacrylate, BEA: behenyl acrylate, OVE: n-octyl vinyl ether-ethylenically unsaturated compound (a2)
2HEA: 2-hydroxyethyl acrylate, 2HEMA: 2-hydroxyethyl methacrylate, 4HBA: 4-hydroxybutyl acrylate-Aromatic OH compound (ethylenically unsaturated compound having a hydroxyl group and an aromatic ring)
HPPA: 2-hydroxy-3-phenoxypropyl-ethylenically unsaturated compound acrylate (a3)
AAEM: 2-acetoacetoxyethyl methacrylate, DAAM: diacetoneacrylamide-ethylenically unsaturated compound (a4)
EA: ethyl acrylate, MMA: methyl methacrylate, MTA: 2-methoxyethyl acrylate-COOH compound (ethylenically unsaturated compound having a carboxyl group)
AA: Acrylic acid-Aromatic ring A (ethylenically unsaturated compound having an aromatic ring)
PHEA: Phenoxyethyl Acrylate

-Reactive surfactant (B)
KH10: Anionic Reactive Surfactant Polyoxyethylene-1- (allyloxyethyl) Alkyl Ether Ammonium Sulfate ["Aqualon KH-10" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.] Non-volatile content concentration: 99%, PD104: Anionic reactive Surfactant Polyoxyethylene alkyl alkenyl ether ammonium sulfate [Kao's "Latemuru PD-104"] Non-volatile content concentration: 20%, ER20: Nonionic reactive surfactant Allyloxymethylalkoxyethyl hydroxypolyoxyethylene [Adeca] "Adecaria Soap ER-20"] Non-volatile content concentration: 75%
-Other Surfactants MS60: Anionic Reactive Surfactants Methylenebispolyoxyethylene Alkylphenylalkenyl Ether Ammonium Sulfate ["Antox MS-60" manufactured by Nippon Embroidery Co., Ltd.] Non-volatile content concentration: 90%, WX: Anionic non-surfactant Reactive Surfactant Polyoxyethylene Alkyl Ether Sodium Sulfate ["Latemuru WX" manufactured by Kao Co., Ltd.] Non-volatile content concentration: 26%
-Polymerization initiator APS: Ammonium persulfate
・ Water W: Ion-exchanged water

<Water-based pressure-sensitive adhesive>
Using the aqueous dispersions of the water-dispersible polymers obtained in Synthesis Examples 1 to 30, water-based pressure-sensitive adhesives were prepared by the following methods.
(Example 1)
In a stirring tank of a stirring device equipped with a stirring tank, a stirrer, and a thermometer, the following water-dispersible polymer (A), reactive compound (C) and other compound (F) {viscosity adjusting agent, defoaming agent, preservative And plasticizer} were charged in the following ratios (both are non-volatile components).

[Stirring tank]
Water-dispersible polymer (A) aqueous solution of Synthesis Example 1 (NV: 55.0%) 100 parts Zirconium tetraacetylacetonate (c1) 0.5 parts Adecanol UH-420 (viscosity adjuster) 1.0 parts SN deformer 154 (antifoaming agent) 0.3 parts Deltop 100N (preservative) 0.05 parts

A homomixer [“LZB46-HM-3” manufactured by Chuo Rika Co., Ltd.] was used as a stirrer, and the mixture was stirred at a rotation speed of 5,000 rpm for 0.5 hours. Next, while stirring, 0.4 part of Acrysol ASE-60 (viscosity adjusting agent), 0.2 part of ammonia water and 4.5 parts of ion-exchanged water were added for adjustment to obtain a water-based pressure-sensitive adhesive. The non-volatile content concentration (NV), solution viscosity (Vis), hydrogen ion index (pH) and gel fraction (Gel%) of the obtained water-based pressure-sensitive adhesive were determined according to the method described below, and the results are shown in Table 2. It is shown in -1 and 2.

(Examples 2 to 62, Comparative Examples 1 to 18)
Among the materials listed in Tables 2-1 and 2, the water-dispersible polymer (A), the reactive compound (C), the viscosity modifier, the defoaming agent, the preservative and the plasticizer are listed in Tables 2-1 and 2. The mixture was blended according to the description and stirred and mixed to obtain water-based pressure-sensitive adhesives.
Each of the obtained water-based pressure-sensitive adhesives was applied to each base material, dried and bonded to prepare an adhesive sheet, which was evaluated by the following method. The respective results are shown in Tables 3-1 and 2.
The aqueous solution of the water-dispersible polymer (A) shown in Tables 2-1 and 2 is the aqueous solution (NV: about 55%) of the water-dispersible polymer of each synthetic example obtained in Table 1-2. be.
The values of the viscosity modifiers shown in Tables 2-1 and 2 are the values of the aqueous solution, and the reactive compound (C), the defoaming agent, the preservative and the plasticizer represent the non-volatile content, and the blanks are not used. Represents that.

<< Non-volatile content concentration (NV) >>
In the same manner as above, about 1 g of the water-based pressure-sensitive adhesive obtained in each Example and Comparative Example is weighed in a metal container, dried in an oven at 150 ° C. for 20 minutes, and the residue is weighed to calculate the residual rate. The non-volatile content concentration (solid content) was used (unit:%).

<< Liquid Viscosity (Vis) >>
The water-based pressure-sensitive adhesives obtained in each Example and Comparative Example were used in the same manner as above at 25 ° C. using a B-type viscometer (TV-22 manufactured by Toki Sangyo Co., Ltd.), rotor Nos. 2-4, rotation speed 0. The viscosity of the liquid (mPa · s) was measured under the conditions of rotation at 5 to 100 rpm for 1 minute.

<< Hydrogen ion index (pH) >>
The pH of the water-based pressure-sensitive adhesives obtained in each Example and Comparative Example was measured using F-52S manufactured by HORIBA and an electrode: model 6377-10D in the same manner as described above.

《Gel%》
The water-based pressure-sensitive adhesive obtained in each Example and Comparative Example was placed on a release liner (polyethylene terephthalate film having a thickness of 38 μm and peeled, Therapy MF: manufactured by Toray Film Processing Co., Ltd.) to increase the thickness after drying. The adhesive layer was formed by coating to 20 μm and drying with hot air at 100 ° C. for 2 minutes. Next, a 50 μm-thick polyethylene terephthalate film (PET film) was bonded to the adhesive layer to prepare an adhesive sheet composed of a 50 μm-thick PET film / adhesive layer / release liner.
Each of the prepared adhesive sheets was cured in an environment of 23 ° C. and 50% relative humidity for 1 day. Then, it is cut into a width of 100 mm and a length of 200 mm, and the surface of the adhesive layer after the peeling liner is peeled off from the end of the adhesive sheet is wrapped in a pre-weighed 200 mesh stainless steel net, which is then put in ethyl acetate. After immersing at 23 ° C. for 72 hours, it was dried to remove the solvent. Then, the ratio of the mass of the dry coating film after immersion to the mass of the dry coating film before immersion was calculated as the gel fraction, and the ratio of the insoluble content was defined as the gel fraction (Gel%) and evaluated in three stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
The gel fraction (Gel%) was calculated by the following method.
(Gel%) = (mass of dry coating film after immersion-mass of PET film) / (mass of dry coating film before immersion-mass of PET film) × 100
[Evaluation criteria]
◯: The gel fraction is in the range of 90% or more and 95% or less. Good.
Δ: The gel fraction is in the range of 85% or more and less than 90%. Can be used practically.
X: The gel fraction is less than 85% or more than 95%. Not practical.

<< Evaluation of storage stability >>
The water-based pressure-sensitive adhesive obtained in each Example and Comparative Example was collected in a 225 ml mayonnaise bottle in the same manner as above, stored at 25 ° C. for 1 month with a lid, and then the water-based pressure-sensitive adhesive was used. The state of separation between the dispersoid and the liquid layer (dispersion medium) was evaluated in three stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: The aqueous dispersion does not separate even after storage for 1 month. Good.
Δ: It separates after storage for 2 weeks or more, but returns to a uniform aqueous dispersion by shaking. Can be used practically.
X: Separation after storage for less than 2 weeks or shaking does not return to a uniform aqueous dispersion. Not practical.

<< Evaluation of mechanical stability >>
50 g of the water-based pressure-sensitive adhesive obtained in each Example and Comparative Example was collected, diluted with 5 g of water and filtered through a 300-mesh wire mesh, and 50 g of the adhesive was used as a test sample. After applying a mechanical load for 10 minutes under the conditions of a temperature of 25 ° C, a load of 15 kg, and a rotation speed of 1,000 rpm using a Maron type mechanical stability tester [manufactured by Tester Sangyo Co., Ltd.], 300 mesh of agglomerates are formed. The dry mass of the agglomerates was calculated with respect to the dry mass of the initial water-based pressure-sensitive adhesive, and the mechanical stability was evaluated in three stages by the production ratio (%) of the agglomerates. In the case of "○" or "△" evaluation, there is no problem in actual use.
The agglutination ratio was calculated by the following method.
Aggregate formation rate (%) = 100 x (aggregate mass) / (initial mass of test sample)
[Evaluation criteria]
◯: The agglutination rate is less than 0.1%. Good.
Δ: The agglutination ratio is 0.1% or more and 1.0% or less. Can be used practically.
X: The agglutination ratio exceeds 1.0%. Not practical.

<< Evaluation of coatability >>
The obtained water-based pressure-sensitive adhesive is placed on a commercially available glassine paper (hereinafter, also referred to as “glassine separator”) that has been peeled off as a peeling liner so that the thickness of the adhesive layer after drying is 18 μm. The adhesive layer was formed by coating and drying at 100 ° C. for 2 minutes with hot air. Next, a commercially available high-quality paper having a thickness of 60 μm was bonded to the coated surface to prepare a high-quality paper / adhesive layer / glassine separator (an adhesive sheet composed of a release liner was prepared, and an adhesive layer after the glassine separator was peeled off. The state of the surface (coated surface) was visually observed and evaluated on a three-point scale. In the case of "○" or "Δ" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: The coated surface is smooth with no repellency, foaming or streaks. Good.
Δ: Some cissing and foaming are observed at the edge of the coated surface. Can be used practically.
X: Repellent, foaming and streaks were observed on the entire coated surface. Not practical.

<< Evaluation of workability >>
Each adhesive sheet prepared by the same method as the above-mentioned << Evaluation of coatability >> was cured in an environment of 23 ° C. and a relative humidity of 50% for 3 days. After that, it was cut into a width of 100 mm and a length of 100 mm, 20 sheets were stacked, and the adhesive layer was projected from the end of the adhesive sheet when pressed at 40 ° C.-60 kg / cm2 for 1 hour as follows. It was evaluated on a three-point scale. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: No protrusion of the adhesive layer is observed. Good.
Δ: Extrusion of the adhesive layer of less than 0.3 mm is observed. Can be used practically.
X: Extrusion of the adhesive layer of 0.3 mm or more is observed. Not practical.

<< Measurement of peel strength >>
Each adhesive sheet produced by the same method as the above << Evaluation of coatability >> was cut into a width of 25 mm and a length of 100 mm, the release liner was peeled off, and the exposed adhesive layer was polished to a surface of 3 mm in thickness. It was attached to a steel plate in an environment of 23 ° C. and a relative humidity of 50%, and a roll having a mass of 2 kg was reciprocated once to obtain a measurement sample. Immediately after that, the adhesive strength was measured in the same environment using a tensile tester ("Tencilon" manufactured by Orientec) under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees (immediately after bonding). Peeling strength measurement).
Further, in the same manner as above, after leaving this measurement sample in an environment of 23 ° C. and a relative humidity of 50% for 1 day, the peel strength was measured under the same conditions under the same environment (peeling strength measurement 1 day after bonding).
Further, the measurement sample was left in an environment of 70 ° C. for 72 hours and then left in an environment of 23 ° C. and a relative humidity of 50% for 1 hour, and the peel strength was measured by the same method (heating time: 72). Measurement of peel strength after time). This peel strength was evaluated as an adhesive strength in three stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: Adhesive strength is 5.0 (N / 25 mm) or more and 8.0 (N / 25 mm) or less. Good.
Δ: Adhesive strength is 3.0 (N / 25 mm) or more and less than 5.0 (mN / 25 mm),
Or, it exceeds 8.0 (N / 25 mm) and is less than 10.0 (mN / 25 mm). Can be used practically.
X: Adhesive strength is less than 3.0 (N / 25 mm) or 10.0 (N / 25 mm) or more. Not practical.

<< Evaluation of high-temperature removability >>
Each adhesive sheet produced by the same method as the above << Evaluation of coatability >> was cut into a width of 25 mm and a length of 100 mm, the release liner was peeled off, and the exposed adhesive layer was polished to a surface of 3 mm in thickness. It was attached to a steel plate in an environment of 23 ° C. and a relative humidity of 50%, and a roll having a mass of 2 kg was reciprocated once to obtain a measurement sample.
Next, this measurement sample was left to stand in an atmosphere of 120 ° C. for 24 hours, then left to stand in the same environment for 1 hour, and then peeled off under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees using a tensile tester. The contamination of the surface of the stainless steel sheet after peeling was visually evaluated on a three-point scale. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: There is no breakage of the base material, and almost no contamination can be confirmed on the stainless steel plate. Good.
Δ: There was no breakage of the base material, but the stainless steel plate was slightly contaminated. Can be used practically.
X: The base material broke or the stainless steel plate remained significantly contaminated. Not practical.

<< Evaluation of high-speed removability >>
Each adhesive sheet produced by the same method as the above << Evaluation of coatability >> is cut into a width of 25 mm × a length of 100 mm, the release liner is peeled off, and the exposed adhesive layer is a commercially available veneer plate having a thickness of 3 mm. The sample was attached to the sample in an environment of 23 ° C. and a relative humidity of 50%, and a roll having a mass of 2 kg was reciprocated once to obtain a measurement sample. Next, this measurement sample was left to stand in an atmosphere of 40 ° C. for 78 hours, then left to stand in the same environment for 1 hour, and then peeled off under the conditions of a peeling speed of 1,500 mm / min and a peeling angle of 180 degrees using a tensile tester. Then, the contamination of the veneer plate surface was visually evaluated on a three-point scale. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: There is no breakage of the base material, and almost no contamination can be confirmed on the veneer plate. Good.
Δ: There was no breakage of the base material, but the veneer plate was slightly contaminated. Can be used practically.
X: The substrate broke or the veneer board remained significantly contaminated. Not practical.

《Measurement of holding power》
Each adhesive sheet produced by the same method as the above << Evaluation of coatability >> is cut into a width of 25 mm × a length of 100 mm, and the release liner is peeled off so that the bonded portion becomes 25 mm × 25 mm, and the exposed adhesive is exposed. The layer was attached to a stainless steel (SUS) plate having a thickness of 3 mm in an environment of 23 ° C. and a relative humidity of 50%, and a roll having a mass of 2 kg was reciprocated once to obtain a measurement sample.
After leaving this measurement sample in an environment of 40 ° C for 20 minutes, a load of 1 kg is applied in an environment of 40 ° C, and a holding force tester [manufactured by Tester Sangyo Co., Ltd.] is used for 70,000 seconds under the condition of 40 ° C. The measurement was performed, and the time until the load dropped, or when the load did not drop, the length deviated from the initial pasting was measured and evaluated in the following three stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: There is no drop of load, and the deviation is less than 0.5 mm. Good.
Δ: There is no drop in load, but the deviation is 0.5 mm or more. Can be used practically.
×: Fall in less than 70,000 seconds. Not practical.

<< Evaluation of constant load peelability test >>
Each adhesive sheet produced by the same method as the above << Evaluation of coatability >> is cut into a width of 10 mm × a length of 100 mm, and the release liner is peeled off so that the bonded portion becomes 10 mm × 80 mm, and the exposed adhesive is exposed. The layer was attached to a stainless steel (SUS) plate having a thickness of 3 mm in an environment of 23 ° C. and a relative humidity of 50%, and a roll having a mass of 2 kg was reciprocated once to obtain a measurement sample.
The obtained measurement sample was left to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours, and then left in an environment of 80 ° C. for 1 hour. Keeping it horizontal, a 50 g weight was hung from the end of the adhesive sheet in the unattached part, left for 10 minutes, and the length of the part peeled off from the stainless steel plate was measured. If all of the stainless steel plate was peeled off within 10 minutes, the time until then was measured and evaluated on a 3-point scale according to the following criteria. The test was conducted in an environment of 80 ° C. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: Does not fall and has a deviation of less than 20 mm. Good.
Δ: No drop, deviation 20 mm or more and less than 80 mm. Can be used practically.
×: Fall in less than 10 minutes. Not practical.

<< Evaluation of curved surface adhesiveness >>
Each adhesive sheet produced by the same method as the above << Evaluation of coatability >> is cut into a width of 20 mm × a length of 22 mm so that the length direction of the sample is along the circumferential direction on the curved surface of a glass cylinder of 20 mmφ. It was affixed to and crimped with a 2 kg rubber roller, and left for 24 hours in an atmosphere of 23 ° C.-50%. Then, the peeling state of the end portion in the length direction of the sample was visually observed and evaluated in three stages according to the following criteria.
[Evaluation criteria]
◯: No peeling is performed, or the portion of the sample end less than 0.1 mm is peeled. Good.
Δ: The portion of 0.1 mm or more and 0.5 mm or less at the end of the sample is peeled off. Can be used practically.
X: The portion of the sample end exceeding 0.5 mm is peeled off. Not practical.

<< Evaluation of substrate adhesion >>
Peel off the release liner from each adhesive sheet prepared by the same method as the above << Evaluation of coatability >> and rub the exposed adhesive layer with a finger to see if the adhesive layer falls off from the base material, woodfree paper. It was evaluated on a three-point scale based on the following criteria. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: Does not fall off from the base material even if rubbed more than 15 round trips. Good.
Δ: It falls off from the base material after 5 to 15 round trips. Can be used practically.
X: The pressure-sensitive adhesive falls off in less than 5 round trips. Not practical.

<< Evaluation of peel strength retention rate >>
The obtained water-based pressure-sensitive adhesive is applied onto a glassine separator (peeling liner) so that the thickness of the adhesive layer after drying is 20 μm, and the adhesive is dried at 100 ° C. for 3 minutes with hot air. Formed a layer. Next, 60 μm thick commercially available acid-free paper (basis weight 80 g / m ² , containing about 15% calcium carbonate) is bonded to the coated surface to form a neutral paper / adhesive layer / glassine separator (peeling liner). An adhesive sheet was prepared.
Each of the produced adhesive sheets was cut into a width of 25 mm and a length of 100 mm, the glassine separator (peeling liner) was peeled off, and the exposed adhesive layer was placed on a stainless steel plate having a thickness of 3 mm and a polished surface at 23 ° C. and a relative humidity of 50%. It was affixed in an environment, and a roll with a mass of 2 kg was reciprocated once to obtain a measurement sample. After leaving this measurement sample in an environment of 23 ° C. and a relative humidity of 50% for 1 day, the peeling speed was 300 mm / min using a tensile tester (“Tencilon” manufactured by Orientec Co., Ltd.) under the same environment for adhesive strength. The peel strength was measured under the condition of a peel angle of 180 degrees (measurement of peel strength one day after bonding).
Further, each of the prepared adhesive sheets was left in an environment of 60 ° C. and a relative humidity of 95% for 3 days, and then left in an environment of another 23 ° C. and a relative humidity of 50% for 1 hour to increase the peel strength by the same method. It was measured (measurement of peel strength after 3 days of humidity and heat).
The obtained adhesive sheet was allowed to stand in a 60 ° C.-95% RH environment for 3 days. The adhesive sheet was then allowed to stand at 23 ° C. in a 50% RH environment for 5 hours. After that, it was prepared into a size of 25 mm in width and 100 mm in length and used as a test piece. Then, the adhesive strength of the adherend was measured by the same method as described above and used as the adhesive strength after a lapse of time. This peel strength was evaluated as an adhesive strength in three stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
[Evaluation criteria]
◯: Adhesive strength is 5.0 (N / 25 mm) or more and 8.0 (N / 25 mm) or less. Good.
Δ: Adhesive strength is 3.0 (N / 25 mm) or more and less than 5.0 (mN / 25 mm),
Or, it exceeds 8.0 (N / 25 mm) and is less than 10.0 (mN / 25 mm). Can be used practically.
X: Adhesive strength is less than 3.0 (N / 25 mm) or 10.0 (N / 25 mm) or more. Not practical.

In addition, the retention rate of the peel strength after 3 days of moist heat and humidity with respect to the peel strength 1 day after bonding was calculated using the following formula, and the deterioration of the adhesive layer with neutral paper was judged with time and evaluated in 3 stages. In the case of "○" or "△" evaluation, there is no problem in actual use.
Peeling power retention rate (%) = (Peeling strength after 3 days of moist heat / Peeling strength after 1 day of bonding) × 100
[Evaluation criteria]
◯: Peeling force retention rate of 90% or more. Good.
Δ: The peeling force retention rate is 85% or more and less than 90%. Can be used practically.
X: The peeling force retention rate is less than 85%. Not practical.

<Abbreviations in Table 2-1 and Table 2-2>
The materials used in Examples, Comparative Examples and Reference Examples are shown below. In Tables 2-1 and 2-2, blanks mean no compounding, and "-" indicates unpainted.
-Water-dispersible polymer About 55% aqueous solution of NV of the water-dispersible polymer (Synthesis Examples 1 to 30) obtained in each of the synthetic examples shown in Tables 1-1 and 1-2-Reactive compound (C)
Mg-acac: magnesium diacetylacetonate, Zr-acac: zirconium tetraacetylacetonate, Ti-acac: titanium tetraacetylacetonate, ADH: adipic acid dihydrazide, ED: ethylenediamine ・ viscosity modifier (F)
UH420: "Adecanol UH-420" manufactured by ADEKA, NV = 30%, ASE60: "Acrysol ASE-60" manufactured by Dow Chemical, NV = 28%
・ Defoamer (F)
SN154: "SN Deformer 154" manufactured by San Nopco Ltd.
・ Preservative (F)
100N: "Dell Top 100N" manufactured by Osaka Gas Chemical Co., Ltd.
・ Plasticizer (F)
ML240: Polyoxyethylene lauryl ether phosphoric acid [manufactured by Toho Chemical Industry Co., Ltd., trade name "Phosphanol ML-240"]
・ Ammonia water AN: 25% ammonia water ・ Water W: Ion-exchanged water

As described above, the water-based pressure-sensitive adhesive of the present invention has Examples 1, 3 to 6, 8, 9, 11 to 15, 18, 19, 21 to 30, 32 to 47, 49, 50, 52 to 55. , 57, 58 and 59-62, storage stability, mechanical stability, coatability, workability, peel strength (immediately after 1 day, after heating 72 hours), re-peelability (high temperature, high speed), retention. "△" evaluation (practical level) is 3 or less out of 16 items in all of force, constant load peeling, curved surface adhesiveness, substrate adhesion and peeling strength (1 day, after 3 days of moist heat, retention rate). And all the others are evaluated as "○" (good level), so it can be seen that they are excellent.
Further, in Examples 2, 7, 10, 16, 17, 20, 31, 48, 51, 56 and 59, the “Δ” evaluation (practical level) of each evaluation is 4 to 16 out of 16 items. , Since there is no "x" evaluation (defective level), it can be used without any problem in practical use.
On the other hand, in Comparative Examples 1 to 18, storage stability, mechanical stability, coatability, processability, peel strength (immediately after 1 day, after heating 72 hours), re-peelability (high temperature, high speed) It can be seen that any of the holding power, constant load peeling, curved surface adhesion, substrate adhesion and peeling strength (after 1 day, after 3 days of moist heat and heat, retention rate) is extremely inferior.

The water-based pressure-sensitive adhesive according to the present invention has excellent storage stability, mechanical stability, coatability, workability, adhesiveness, re-peelability, curved surface adhesiveness, constant load peelability, and substrate adhesion. In addition to the general field of labels and sheets, the field of construction (for example, exterior, interior, equipment, etc.), electrical equipment field (for example, home appliances, kitchen equipment, air conditioning, etc.), transport equipment, etc. It can also be used in various industrial fields other than the optical field such as fields (for example, ships, automobiles, etc.), furniture fields, and miscellaneous goods fields.

Claims (8)

It contains a water-dispersible polymer (A) having a hydroxyl group and a carbonyl group and no carboxyl group, and a reactive compound (C) having a functional group capable of reacting with at least one of the hydroxyl group and the carbonyl group.
The water-dispersible polymer (A) is a copolymer of a mixture containing the following ethylenically unsaturated compounds (a1) to (a3).
A water-based pressure-sensitive adhesive containing 0.01 to 10 parts by mass of the reactive compound (C) with respect to 100 parts by mass of the water-dispersible polymer (A) and not containing a compound having an aromatic ring.

(A1) Ethylene unsaturated compound having an alkyl group having 4 to 24 carbon atoms (a2) Ethylene unsaturated compound having a hydroxyl group (a3) Ethylene unsaturated compound having a carbonyl group In 100% by mass of the mixture of ethylenically unsaturated compounds constituting the water-dispersible polymer (A),
Ethylene unsaturated compound (a1) 70-99.98% by mass,
Ethylene unsaturated compound (a2) 0.01 to 20% by mass and
Ethylene unsaturated compound (a3) 0.01-10% by mass,
The water-based pressure-sensitive adhesive according to claim 1, which comprises. The water-based pressure-sensitive adhesive according to claim 1 or 2, wherein the reactive compound (C) contains a metal chelate compound. The water-based pressure-sensitive adhesive according to claim 3, wherein the metal of the metal chelate compound is at least one of magnesium and zirconium. Claim 1 is characterized in that the functional group of the reactive compound (C) is at least one selected from the group consisting of an amino group, an imino group, a hydrazino group, and a nitrogen-containing heterocyclic group having active hydrogen. ~ 4 The water-based pressure-sensitive adhesive according to any one of Items 1. The water-dispersible polymer (A) is obtained by emulsion polymerization of a mixture of ethylenically unsaturated compounds in the presence of a reactive surfactant (B) (excluding the reactive compound (C)). The water-based pressure-sensitive adhesive according to any one of claims 1 to 5. The water-based pressure-sensitive adhesive according to claim 6, wherein the reactive surfactant (B) contains an anionic reactive surfactant. An adhesive sheet comprising a base material and an adhesive layer formed of the water-based pressure-sensitive adhesive according to any one of claims 1 to 7.