JP2014047219A - Water-in-oil type emulsion adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive which has excellent storage stability, which is scarcely solidified even when placed inside a machine or the like for a predetermined period, and which has long usable time for re-sticking.SOLUTION: A water-in-oil type emulsion adhesive is constituted of an oil phase and a water phase. The water phase includes a water-soluble polymer. The oil phase includes a solvent with a standard boiling point of 300 to 400°C and an SP value of 8 to 10 (cal/cm), and the oil phase includes 2 to 6 mass% of a resin which is solid at 30°C and which has an acid value of 11 to 100 based on the total amount of the adhesive.

Description

  The present invention relates to a water-in-oil (W / O) emulsion adhesive that is preferably used particularly for paper.

As methods for adding value to image-formed paper, booklet production and sealed letter production have attracted attention. For example, in direct mail or the like, a so-called self-mailer that folds paper into an envelope type is used.
To produce a booklet or sealed letter of any size and shape by in-line automation using a post-processing device (finisher) after printing, such as a letter making device or booklet making device, Ensuring drying and storage stability is a problem.

In other words, booklet production and sealed letter production are not necessarily used frequently, so that the adhesive may be left in a machine that is not in a sealed state for a long time. Therefore, when the adhesive is dried and solidified while being left in an open space, poor application of the adhesive will occur.
Further, if separation or alteration of the adhesive occurs during the standing, defective application of the adhesive, poor adhesion, or the like occurs.
Furthermore, when it is necessary to adjust the position of the bonding portion after applying and bonding the adhesive to the paper, it is required that the adhesive can be reattached for a long time. Here, “the time when the adhesive can be reapplied” means that after the adhesive is applied to the adherend (substrate or adherend) and the adherends are bonded together, the adhesive is peeled off and reattached. It means possible time. That is, when the adhesive is applied and the adherends are left to stand, the adhesive film is formed after a certain period of time. Even if it is peeled once and the adherend is overlapped again, the adhesive component penetrates into the adherend and does not remain on the surface, which may result in insufficient adhesion performance.

  Conventionally, an aqueous adhesive in which a water-soluble polymer such as polyvinyl alcohol or polyvinyl acetate is dissolved in water is known as an adhesive for paper (Patent Document 1). An oil-in-water (O / W) type resin emulsion adhesive in which polymer particles such as vinyl acetate resin are dispersed in water with an emulsifier or a protective colloid has also been proposed (Patent Documents 2 and 3).

JP 2000-26825 A JP-A-11-92734 JP 2000-282004 A

However, both of these known aqueous adhesives and aqueous emulsion adhesives are not suitable for in-line use because they are dried and solidified by evaporation of moisture when left in a machine.
Further, when a conventional adhesive is used for a permeable adherend such as paper, there is a problem that the adhesive penetrates into the adherend and the re-applicable time is shortened.

  Therefore, the present invention provides an adhesive that has excellent storage stability, does not easily solidify even when placed in a machine for a certain period of time, and has a long re-applicable time even when used on a permeable substrate such as paper. The issue is to provide.

The present invention comprises an oil phase and an aqueous phase, the aqueous phase contains a water-soluble polymer, and the oil phase has a normal boiling point (a boiling point at 1 atm) of 300 ° C. or more and 400 ° C. or less and The oil phase contains a solvent having an SP value of 8 to 10 (cal / cm ³ ) ^1/2 and the oil phase is solid at 30 ° C. and has an acid value of 11 to 100 with respect to the total amount of the adhesive. The present invention relates to a water-in-oil emulsion adhesive containing 2 to 6% by mass.

  The emulsion adhesive of the present invention is excellent in storage stability and hardly solidifies even when placed in an open space for a certain period. Furthermore, the emulsion adhesive of the present invention has a long repossible time, and even after the adhesive is applied to an adherend such as paper and the adherends are bonded together, the adhesive is peeled off and the position of the bonded portion Adjustments can be made.

Hereinafter, preferred embodiments of the water-in-oil (W / O) emulsion adhesive (hereinafter also simply referred to as “adhesive”) according to the present invention will be described.
According to the present invention, since the adhesive is in the form of a water-in-oil emulsion and the adhesive component is included in the aqueous phase, the oil phase surrounding the adhesive component is less likely to evaporate, and as a result, in an open space. It is thought that the effect that it is hard to solidify even if left unattended is obtained. In the present invention, since a solvent having a high normal boiling point and low volatility is used, this storage stability can be further enhanced.

In the present invention, a resin having a high acid value that is solid at normal temperature is contained in the oil phase. When an adhesive is applied to the adherend, the resin is removed from the solvent as the solvent penetrates into the adherend. It is considered that it leaves and remains on the surface of the adherend while retaining a part of the solvent. In this way, as a result of the resin holding the low-volatile solvent remaining on the surface of the adherend, it is possible to prevent a rapid decrease in the solvent from the surface of the adherend, and thus to ensure a long time for reattachment. It is thought that you can. That is, when the solvent remains on the paper surface, the solvent is difficult to adhere by preventing the evaporation of water from the aqueous phase and the adhesion between the adhesive component and the substrate. The solvent remaining on the surface of the adherend gradually penetrates into the base material over time due to capillary action, and when a certain amount of solvent penetrates and decreases, the adhesive component and oil phase contained in the aqueous phase are reduced. It is thought that the resin contained forms a film and adheres. As described above, the length of the re-stickable time can be controlled by the amount of the resin contained in the oil phase.
Here, if the solvent remaining in the adherend dissolves or swells the water-soluble polymer that is the adhesive component, the adhesive strength may decrease, but the compatibility with the water-soluble polymer It is considered that a decrease in adhesive strength can be suppressed by using a solvent having a low SP value of 8 to 10 (cal / cm ³ ) ^1/2 .

The aqueous phase of the adhesive contains a water-soluble polymer that serves as an adhesive component. The adhesive component is a component that develops adhesiveness and has a binding ability and a film forming ability and can form an adhesive film.
It is not particularly limited as long as it is a water-soluble polymer that exhibits adhesiveness. For example, a known polymer can be used as an adhesive component of an aqueous adhesive. Since it is a water-soluble polymer, the stability of the emulsion is maintained.
Specific examples include natural polymers such as starch and glue, synthetic polymers such as polyvinyl alcohol and derivatives thereof, water-soluble cellulose, and polyvinylpyrrolidone. You may mix | blend combining multiple types of water-soluble polymer. As these, commercially available products can be used. For example, various starch pastes such as those manufactured by Yamato Co., Ltd., or manufactured by Non-Easy Paste Industry Co., Ltd. can be preferably used.

  The blending amount of the water-soluble polymer is not particularly limited, but it is more preferably 10% by mass or more in the total amount of the adhesive from the viewpoint of securing the adhesive strength. On the other hand, in order to suppress the film formation (stand-drying property) when left open and to secure the time until solidification and to obtain a longer re-applicable time, the water-soluble polymer in the adhesive The content is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less.

Especially, it is preferable that water-soluble resin contains polyvinyl alcohol (PVA). PVA has a high SP value, and even when it remains on the paper surface together with the solvent, dissolution and swelling by the solvent are unlikely to occur. Moreover, since a tough film can be obtained by using PVA having a high degree of polymerization, the adhesive strength can be increased. PVA may be derivatized such as acetoacetylated, aminated, cationized, anionized, silanol modified.
PVA changes in viscosity and other properties depending on the polymerization degree and saponification degree, and PVA having a low saponification degree and a low polymerization degree generally has problems such as poor water resistance of a cured film. However, in the present invention, PVA having various degrees of polymerization and valency can be preferably used. This is because the resin blended in the oil phase remains on the surface of the adherend and contributes to the enhancement of the adhesive film. Therefore, even when PVA with a low degree of polymerization and / or saponification is used, the adhesive film is sufficient. This is because it has excellent adhesive strength and water resistance.

Furthermore, in the conventional PVA water-based adhesive, even a PVA having a high saponification degree and / or a high polymerization degree which is not suitable for use from the viewpoint of adjusting the viscosity can be used widely. This is because in emulsion adhesives, even if the viscosity of the aqueous solution, that is, the viscosity of the aqueous phase, does not significantly affect the viscosity of the entire emulsion, therefore, the effect on the viscosity of the aqueous solution is taken into consideration. PVA can be selected and used without doing so.
Based on the same reason that it is not necessary to adjust the viscosity of the aqueous phase, PVA having a low saponification degree and a low polymerization degree can be used at a high concentration to further improve the water resistance and the like. Thus, it is preferable to set the compounding quantity of PVA suitably according to the kind of PVA to be used.

  It is preferable to use PVA having a saponification degree of 70 mol% or more from the viewpoint of securing a solubility in water to form a stable emulsion and ensuring disintegration of the emulsion when applied to an adherend. Although fully saponified PVA can be used, intermediate saponified PVA is more preferably used.

The degree of polymerization of PVA is not particularly limited, but from the viewpoint of the strength of the adhesive film, it is preferable to use a polymer having a polymerization degree of 250 or more, more preferably 500 or more, and 1000 or more. More preferably. In general, when a PVA having a polymerization degree of 2000 or more is used, the aqueous solution has a high viscosity and is inferior in workability. Therefore, it is rarely used as an aqueous adhesive. On the other hand, in the emulsion adhesive as described above, there is no problem even if the viscosity of the aqueous phase is high. For example, a polymerization degree that is unsuitable for an aqueous adhesive such as a polymerization degree of 3000 or more. High PVA can also be used. Thereby, the strength of the adhesive film is increased, and sufficient adhesive strength can be exhibited even when thinly coated on the substrate. The upper limit of the degree of polymerization of PVA is not particularly limited, but is preferably about 7000 or less and preferably 6000 or less in order to suppress solidification of the adhesive when left in an open space for a certain period. More preferred.
PVA may be synthesized according to a known production method, or various commercially available PVA can be used. A plurality of PVA having different degrees of saponification and / or polymerization may be used in combination.

  Polyvinyl pyrrolidone (PVP) having various molecular weights can also be used. It is preferable to use PVP having a molecular weight of 40,000 or more because the strength of the adhesive film increases as the molecular weight of PVP increases, and sufficient adhesive strength can be exhibited even when thinly applied onto the substrate. The upper limit of the molecular weight of PVP is not particularly limited, but is preferably 1.3 million or less from the viewpoint of suppressing solidification when left open. Here, “molecular weight” means a mass (weight) average molecular weight measured by GPC (standard polystyrene conversion).

  In the aqueous phase, in addition to the water-soluble polymer, one or more known water-soluble additives such as a wetting agent, an electrolyte, an antifungal agent, an antioxidant, a water evaporation inhibitor, and a pH adjuster are added as necessary. , Can be included.

Next, the oil phase will be described.
The oil phase contains a resin having an acid value of 11 to 100 that is solid at 30 ° C. (hereinafter also referred to as a solid resin). The acid value is represented by the number of mg of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample (KOH mg / g). The acid value can be measured by a measurement method defined in JIS K2501. If the acid value of the solid resin is 11 or more, it is possible to secure a long adhesive re-practicable time, and if the acid value is 100 or less, the final adhesive strength can be ensured. preferable.

In the oil phase, it is preferable to blend a resin for emulsion stabilization (storage stability), but according to the study by the present inventors, if the resin blended in the oil phase is a liquid, The resin penetrates into the adherend together with the solvent, and as a result, a non-uniform gap having a size of several μm to several tens of μm may be formed in the water-soluble polymer film formed on the adherend surface. found. It has also been found that if the liquid resin has a high viscosity so that it does not penetrate into the adherend, the adhesion of the water-soluble resin to the adherend surface is caused.
On the other hand, if it is a solid resin in a normal use environment (30 ° C. or less), it does not penetrate into the adherend and remains on the surface, as if filling the gap between the water phase particles. By being present, a uniform adhesive film without gaps can be formed together with the water-soluble polymer, and as a result, the adhesive strength can be improved.
This solid resin is preferably dissolved in an oil phase solvent. This is because when the resin is dissolved in the solvent, the resin tends to remain on the surface of the base material while retaining the solvent.

Furthermore, by adding and dissolving the resin in the oil phase, the viscosity of the oil phase is increased and the stability of the emulsion is improved. When only the solvent is used as the oil phase without the resin, the viscosity of the oil phase (general-purpose stress control rheometer (AR-G2, manufactured by D.A. Instruments Japan Co., Ltd.) is used. (Measured by increasing the shear stress from 0 Pa to 10 Pa at a rate of 0.1 Pa / s) is as low as about 5 to 100 mPa · s, so the aqueous phase particles are likely to coalesce and the stability of the emulsion is reduced. It is not preferable. In contrast, by dissolving the resin in the solvent, the viscosity of the oil phase can be increased to 500 mPa · s or more, and coalescence of the water phase particles can be prevented.
Moreover, the solid content concentration of the adhesive is increased by adding the resin, and the adhesive strength when sufficiently dried can be improved. On the other hand, solid content concentration contained in the system may increase, and solidification when left to dry may be promoted. Therefore, the solid content (including at least the water-soluble polymer and the solid resin) contained in the adhesive is preferably 40% by mass or less, more preferably 35% by mass or less, and 30% by mass or less. More preferably.

  The type of solid resin is not particularly limited as long as it is solid at 30 ° C. and has an acid value of 11 or more and 100 or less. For example, rosin ester resin, alkylphenol resin, rosin-modified phenol resin, terpene phenol resin, petroleum resin An alkyd resin, a maleic acid resin, a styrene-acrylic resin, a styrene-maleic resin, an acrylic resin, or the like can be preferably used. A plurality of resins having different acid values and / or types may be used in combination.

  The content of the solid resin should be 2% by mass or more based on the total amount of the adhesive in order to secure a viscosity of the oil phase to obtain a stable emulsion, and to obtain a long re-applicable time while retaining the solvent. Preferably, it is 3 mass% or more. On the other hand, if the content of the solid resin is too large, the adhesive strength is improved, and there is a risk that material destruction occurs at the time of peeling, making it difficult to reattach. The content is preferably at most mass%, more preferably at most 5 mass%.

  Other resins than the above solid resin can be blended in the oil phase within a range that does not impair the desired effect of the present invention. Examples of resins that can be used in combination include ethylene-vinyl acetate resin, coumarone indene resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, vinyl chloride-vinyl acetate copolymer (vinyl acetate vinyl chloride). Resin), xylene resin, aliphatic hydrocarbon resin, butyral resin, fumaric acid resin and the like.

  The oil phase of the adhesive becomes an outer phase of the water phase particles and needs to have a function of suppressing evaporation of moisture from the water phase. Therefore, for the oil phase, a solvent having a standard boiling point (boiling point at 1 atm) of 300 ° C. or higher is used as a solvent that hardly volatilizes even when left open. On the other hand, when the oil phase solvent is applied to the base material, it is preferable that the oil phase is dispersed by permeating and evaporating into the base material while ensuring an appropriate re-applicable time. The coalescence of the particles proceeds and an adhesive film is formed. Therefore, it is preferable to select an oil phase solvent having a normal boiling point of 400 ° C. or less.

Furthermore, as described above, it is preferable to use a solvent that can dissolve the solid resin and has low compatibility with the water-soluble polymer. From such a viewpoint, a solvent having an SP value of 8 to 10 (cal / cm ³ ) ^1/2 is used.
The SP value is a value for evaluating the solubility of the solid resin in the solvent, and is calculated by Fedor's estimation method. That is, it can be defined by the following formula (1) from the total ΣE _coh of the cohesive energy density of each functional group of the substance and the total ΣV of the molar molecular volume.
[Formula 1]
δ (SP value) = (ΣE _coh / ΣV) ^1/2 (1)
(Refer to “Application Examples of Solubility Parameters” (based on mechanism and solubility evaluation / calculation examples), pages 97 to 100, Information Organization Co., Ltd., issued on March 15, 2007)
The SP value of the solvent is more preferably 8 to 9 (cal / cm ³ ) ^1/2 .

By selecting a solvent with an SP value of 8 (cal / cm ³ ) ^1/2 or more, the solubility of the solvent and the solid resin is increased, the solid resin is prevented from precipitating from the solvent, and solidified when left open. Leads to suppression. Specifically, the SP value of the rosin ester resin (weight average molecular weight: 10,000 to 45000) is 7 to 10 (cal / cm ³ ) ^1/2 and the alkylphenol resin (weight average molecular weight: 10,000 to 500,000). Has an SP value of 8 to 12 (cal / cm ³ ) ^1/2 , and an SP value of an aliphatic (C5 fraction) petroleum resin (weight average molecular weight: 1500 to 5000) is 8 to 10 (cal / cm ³ ) ^{1. / 2} . By using a solvent having an SP value of 8 or more, the SP value of the resin and the solvent are identical or very close to each other, so that the solubility of the resin in the solvent can be enhanced.

On the other hand, the compatibility with the water-soluble polymer can be lowered by using a solvent having an SP value of 10 (cal / cm ³ ) ^1/2 or less. Specifically, the SP value of PVA (saponification degree: 60 to 100%, polymerization degree: 2000 to 5000), which is a water-soluble resin, is 15 to 20 (cal / cm ³ ) ^1/2 , polyvinylpyrrolidone ( The SP value of the weight average molecular weight: 40,000 to 360,000) is 12 to 14 (cal / cm ³ ) ^1/2 . When the SP value of the solvent is high and close to the SP value of the water-soluble resin, the remaining solvent dissolves or swells the water-soluble resin, which is not preferable. By selecting a solvent having an SP value of 10 (cal / cm ³ ) ^1/2 or less, the compatibility between the solvent and the water-soluble resin is lowered, and dissolution or swelling of the water-soluble resin can be prevented.

It is possible to use a mixture of two or more solvents as the oil phase solvent. In order to further improve the stability of the emulsion when the adhesive is left open, the SP value is 8 to 10 ( It is most preferred to use only one solvent which is cal / cm ³ ) ^1/2 . The SP value (δ ₁₂ ) of a two-component mixed solvent when using two or more components mixed is calculated according to the following formula, and the calculated SP value is 8 to 10 (cal / cm ³ ) ^1/2 Can only be used if The same calculation is performed for a system with three or more components.
[Formula 2]
δ ₁₂ = X ₁ δ ₁ + X ₂ δ ₂ (2)
(Δ _1, δ _2: SP value of each solvent, X _1, X _2: shows the mass fraction of each solvent.)

  Furthermore, a solvent having an SP value in the above range is a “non-aqueous solvent” that is excellent in solubility of the solid resin and has a solubility in water of 20 g / L or less when mixed with water. By gradually adding the water phase component to the oil phase and emulsifying, a stable W / O emulsion can be easily prepared.

  The solvent is not particularly limited as long as it satisfies the above characteristics (standard boiling point and SP value). For example, ester solvents, ether solvents, alcohol solvents, higher fatty acid solvents, aromatic hydrocarbon solvents. Various solvents such as hydrocarbon solvents such as aliphatic hydrocarbon solvents, paraffin hydrocarbon solvents, isoparaffin hydrocarbon solvents, and naphthene hydrocarbon solvents can be used.

From the viewpoint of the solubility of the solid resin, an ester solvent is particularly preferably used, and an ester of a saturated or unsaturated aliphatic carboxylic acid is most preferably used among the ester solvents. Moreover, it is preferable that carboxylic acid is monocarboxylic acid and dicarboxylic acid from a viewpoint of the permeability of the solvent at the time of apply | coating to an adherend, ie, the viscosity of a solvent. The carboxylic acid preferably has about 8 to 20 carbon atoms and may be linear or branched.
The alcohol moiety constituting the ester is not particularly limited, and is preferably an alkyl group having 1 to 18 carbon atoms. This alkyl group may have a branched chain or a free hydroxyl group.
The number of carbon atoms of the entire carboxylic acid ester is not particularly limited, but is preferably about 12 to 30, and most preferably about 15 to 20.

  The alcohol solvent is not particularly limited as long as it has the above SP value, and is not limited to monool, and polyol can also be used and may contain an unsaturated group. The carbon number is more preferably about 10 to 20, and still more preferably about 15 to 18.

More specifically, it is not limited to these. For example,
Alcohols such as cetyl alcohol (9.54 (cal / cm ³ ) ^1/2 ), stearyl alcohol (9.45 (cal / cm ³ ) ^1/2 ), oleyl alcohol (9.67 (cal / cm ³ ) ^1/2 );
Isononyl isononanoate (SP value: 8.13 (cal / cm ³ ) ^1/2 ), hexyl laurate (8.62 (cal / cm ³ ) ^1/2 ), isopropyl laurate (8.54 (cal / cm ³ ) ^1/2 ) , Isopropyl myristate (8.54 (cal / cm ³ ) ^1/2 ), isooctyl myristate (8.54 (cal / cm ³ ) ^1/2 ), isostearyl palmitate (8.55 (cal / cm ³ ) ^1/2 ), Methyl oleate (8.63 (cal / cm ³ ) ^1/2) , ethyl oleate (8.63 (cal / cm ³ ) ^1/2 ), isopropyl oleate (8.56 (cal / cm ³ ) ^1/2 ), oleic acid Butyl (8.62 (cal / cm ³ ) ^1/2 ), Methyl linoleate (8.64 (cal / cm ³ ) ^1/2 ), Isobutyl linoleate (8.79 (cal / cm ³ ) ^1/2 ), Ethyl linoleate ( ^{8.63 (cal / cm 3) 1/2} ), isopropyl isostearate ^{(8.47 (cal / cm 3)} 1/2), tri-2-ethylhexanoate of trimethylolpropane ^{(9.06 (cal / cm 3)} 1/2 Ester solvents such as glyceryl tri-2-ethylhexanoate ^{(9.18 (cal / cm 3)} 1/2); and the like preferably. The numerical value in parentheses indicates the SP value of the solvent.

  The specific solvent satisfying the above characteristics is preferably contained in an amount of 6% by mass or more, more preferably 9% by mass or more, and 12% by mass from the viewpoint of suppressing solidification when left open. % Or more is more preferable. On the other hand, the amount of the solvent is preferably 35% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less in the total amount of the adhesive. When applied to an adherend such as paper, it is preferable that the solvent penetrates the adherend and only the aqueous phase adhesive component remains on the surface of the adherend. The amount of the solvent is more than 35% by mass. If it is contained, the solvent cannot completely penetrate into the adherend and remains on the adherend surface, which may hinder the adhesiveness between the adhesive film and the adherend and reduce the adhesive strength.

The oil phase may contain other organic solvents other than the specific solvent as long as the effects of the present invention are not impaired. Other solvents that can be used in combination include motor oil, spindle oil, machine oil, mineral oil such as liquid paraffin, vegetable oil such as olive oil, castor oil, salad oil; aromatic hydrocarbon solvent, aliphatic hydrocarbon solvent, aromatic hydrocarbon And hydrocarbon solvents such as mixed solvents of aliphatic and aliphatic hydrocarbons, paraffinic hydrocarbon solvents, isoparaffinic hydrocarbon solvents, and naphthene hydrocarbon solvents. These other solvents can be used alone or in admixture of two or more.
When the other solvent is used in combination, the specific solvent is preferably contained in an amount of 60% by mass or more, and more preferably 80% by mass or more in the total solvent constituting the oil phase.

  A solubilizing agent may be used in the oil phase in order to improve the solubility of the solid resin. The solubilizing agent is not particularly limited as long as it is an additive that facilitates dissolution of the solid resin in the solvent. For example, alkylbenzene, chlorinated paraffin, phthalic acid ester, higher fatty acid and the like are preferable. I can give you. Such a solubilizing agent may be used alone or in combination of two or more.

  In order to constitute a W / O type emulsion, it is preferable to use an emulsifier in the oil phase. Although not particularly limited, a nonionic surfactant is preferably used. In order to produce a stable W / O emulsion, among nonionic surfactants, those having an HLB of 10 or less are particularly preferably used. HLB as used herein is an abbreviation for Hydrophile Lipophile Balance and is a numerical value indicating the balance between hydrophilic groups and lipophilic groups in the emulsifier. A higher HLB value indicates a hydrophilic emulsifier, and a lower HLB value indicates a lipophilic emulsifier. If an emulsifier having an HLB of 10 or more is used, the hydrophilicity of the emulsifier becomes strong, so that it becomes easier to produce an O / W emulsion than a W / O emulsion, which is not preferable.

As such nonionic surfactant,
Higher alcohols, alkylphenols, fatty acids;
Polyoxyethylene 2-30 mol addition (hereinafter abbreviated as POE (2-30)) olein ether, POE (2-35) stearyl ether, POE (2-20) lauryl ether, POE (1-20) alkylphenyl Ether, POE (6-18) behenyl ether, POE (5-25) 2-decylpentadecyl ether, POE (3-30) 2-decyltetradecyl ether, POE (8-16) 2-octyldecyl ether, etc. Ether type surfactants;
Ester type surfactants such as POE (4-60) hydrogenated castor oil, POE (3-14) fatty acid monoester, POE (6-30) fatty acid diester, POE (5-20) sorbitan fatty acid ester;
POE (2-30) glyceryl monoisostearate, POE (10-60) glyceryl triisostearate, POE (7-50) hydrogenated castor oil monoisostearate, POE (12-60) hydrogenated castor oil triisostearate Ether ester type surfactants such as a rate; (The above ether type surfactants, ester type surfactants, and ether ester type surfactants are collectively referred to as "ethylene oxide addition type surfactants")
Sorbitan higher fatty acid ester, polyoxyethylene sorbitan higher fatty acid ester, glycerin fatty acid ester (polyglyceryl polyoleate, polyglyceryl polyricinoleate, fatty acid monoglyceride, fatty acid diglyceride, decaglyceryl tetraoleate, hexaglyceryl triisostearate, diglyceryl diisostearate Polyhydric alcohol fatty acid ester type surfactants, such as rate and glyceryl monooleate).
These nonionic surfactants may be used alone or as a mixture as appropriate.

Furthermore, a colorant such as a pigment and a dye, a pigment dispersant, an inorganic filler, and the like can be blended in the oil phase.
Arbitrary components other than those described above may be blended, and the optional components can be blended in an appropriate phase of the water phase and the oil phase according to the solubility characteristics of the components.

The ratio of the water phase and the oil phase of the adhesive is not particularly limited, and for example, the oil phase component can be configured to be 10 to 70% by mass, and the water phase component can be configured to be 90 to 30% by mass. From the viewpoint of the stability of the emulsion, the amount of the aqueous phase is more preferably 85% by mass or less, and from the viewpoint of securing the adhesive film hardness and increasing the adhesive strength, the aqueous phase is 60% by mass or more. It is more preferable that
The W / O emulsion adhesive can be produced by gradually adding a water phase component to an oil phase component and emulsifying it.

The adherend (base material) to which the adhesive is applied is not particularly limited, but it is preferable that the oil phase easily penetrates into the adherend after application of the adhesive, and therefore, it is a permeable base material such as paper. preferable. The type of paper is not particularly limited, and can be widely applied to plain paper, high-quality paper, coated paper, art paper, and the like.
The use of the adhesive is not particularly limited. Although it is preferable to use it for post-processing after printing, it may be used before printing or may be used other than printed matter.

The application method of the adhesive is not particularly limited, and various application devices such as a syringe, a dispenser, a nozzle, an applicator, a coater, and a hand pump can be used.
In order to produce a booklet or a sealed letter, an application mechanism can be incorporated into a post-processing apparatus (finisher), and an adhesive can be applied by patterning in a required place in-line.
As described above, the adhesive according to the present invention is characterized in that it can ensure a long re-applicable time, but if necessary, the drying is accelerated by heating so as to express the adhesive strength more quickly. , And can be used while arbitrarily adjusting the possible re-stick time.

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to these examples.
<Example 1>
Rosin ester resin (1) as solid resin (“Pencel D-125” manufactured by Arakawa Chemical Industries, Ltd., acid value: 13 (KOH mg / g), solid at room temperature (30 ° C.)) 5 g, hexyl laurate (cog) “Cethiol A” manufactured by Nix Japan Co., Ltd., SP value: 8.62 (cal / cm ³ ) ^1/2 , standard boiling point: 335 ° C., dissolved in 13 g, polyglyceryl-6 polyricinoleate (Nikko Chemicals Co., Ltd.) as an emulsifier 2 g of company “NIKKOL Hexaglyn PR-15”) was added and stirred for 5 minutes to obtain an oil phase. As a water-soluble polymer, 20 g of polyvinyl alcohol (“PVA405” manufactured by Kuraray Co., Ltd., saponification degree: 81.5 mol%, polymerization degree: 500) was dissolved in 60 g of water to prepare a PVA aqueous solution, which was used as an aqueous phase. The aqueous phase was continuously added to the oil phase over 20 minutes for emulsification to obtain a W / O type emulsion adhesive. During the addition of the aqueous phase, the oil phase was always stirred with a batch-type tabletop sand mill (made by Campe, using a high-viscosity stirring blade, rotation speed: 2100 rpm), and further stirred for 10 minutes after the addition was completed.

<Example 2>
The same as in Example 1 except that alkylphenol resin (“TAMANOL 100S” manufactured by Arakawa Chemical Industries, Ltd., acid value: 85 to 100 (KOH mg / g), solid at room temperature (30 ° C.)) was used as the solid resin. An adhesive was prepared according to the procedure.

<Example 3>
Implemented except that aliphatic (C5 fraction) petroleum resin (“Quiontone D200” manufactured by Zeon Corporation, acid value: 17 (KOH mg / g), solid at room temperature (30 ° C.)) was used as the solid resin An adhesive was prepared in the same procedure as in Example 1.

<Example 4>
An adhesive was prepared in the same procedure as in Example 3 except that 3 g of the petroleum resin was dissolved in 15 g of the hexyl laurate.

<Example 5>
An adhesive was prepared in the same procedure as in Example 3 except that 2 g of the petroleum resin was dissolved in 16 g of the hexyl laurate.

<Example 6>
Except that 24 g of polyvinylpyrrolidone (“K-90” manufactured by Wako Pure Chemical Industries, Ltd., molecular weight: 360000) as a water-soluble polymer was dissolved in 56 g of water to prepare an aqueous PVP solution, and this was used as an aqueous phase. An adhesive was prepared in the same manner as in 3.

<Example 7>
An adhesive was prepared in the same procedure as in Example 3 except that starch paste (manufactured by Yamato Co., Ltd.) was used as a water-soluble polymer after adjusting to a solid content of 20 g.

<Example 8>
As in Example 3, except that isopropyl isostearate (“NIKKOL IPIS” manufactured by Nikko Chemicals Co., Ltd., SP value: 8.47 (cal / cm ³ ) ^1/2 , standard boiling point: 368 ° C.) was used as the solvent for the oil phase. An adhesive was prepared by the procedure described above.

<Example 9>
An adhesive was prepared in the same manner as in Example 7, except that the amount of the water-soluble polymer was 24 g in solid content and the amount of the solid resin was 5 g.

<Comparative Example 1>
A naphthenic petroleum-based hydrocarbon solvent ("AF Solvent No. 6" manufactured by JX Nippon Oil & Energy Corporation, SP value 7.00 (cal / cm ³ ) ^1/2 , standard boiling point: 306 ° C) was used as an oil phase solvent. Except for this, an adhesive was prepared in the same procedure as in Example 4.

<Comparative example 2>
An adhesive was prepared in the same procedure as in Example 4 except that 1-dodecanol (SP value: 9.81 (cal / cm ³ ) ^1/2 , standard boiling point: 260 to 262 ° C.) was used as the oil phase solvent.

<Comparative Example 3>
The same procedure as in Example 4 was used except that tri-2-ethylhexyl citrate (SP value 13.18 (cal / cm ³ ) ^1/2 , boiling point 537 ° C., manufactured by Nippon Surfactant Co., Ltd.) was used as the oil phase solvent. An adhesive was prepared.

<Comparative Example 4>
The same procedure as in Example 1 except that the rosin ester resin (2) (“Neotorl 101N” manufactured by Harima Kasei Co., Ltd., acid value: 8.9 (KOHmg / g), solid at 30 ° C.) was used as the solid resin. An adhesive was prepared.

<Comparative Example 5>
An adhesive was prepared in the same procedure as in Example 3 except that 7 g of the petroleum resin was dissolved in 11 g of hexyl laurate.

<Comparative Example 6>
An adhesive was prepared in the same manner as in Example 8 except that 18 g of the isopropyl isostearate was used without using a solid resin.

<Evaluation method>
The adhesives obtained in Examples and Comparative Examples were subjected to static storage stability, standing drying property, adhesion test, and peel test as follows. The results are shown in Table 1.
1. Static Storage Stability Test 50 g of the adhesive was weighed into a sealed container, and the presence or absence of free water was visually confirmed 10 days after the emulsification step.
○: No free water generated even after 10 days from the emulsification step.
X: Free water is generated in less than 10 days from the emulsification step.

2. Standing drying property An adhesive was applied in a circle having a thickness of 3 mm and a diameter of 3 mm on a metal plate, which is a non-absorbing substrate, and left at room temperature (30 ° C.). It was visually confirmed whether or not a film was formed on the adhesive surface every hour.
A: No film was formed on the adhesive surface even after 24 hours of standing.
○: A film was not formed on the adhesive surface even after 5 hours.
X: A film was formed on the adhesive surface within 5 hours.
Table 1 also shows the time when film formation was confirmed.

3. Adhesion test (1) (Adhesion at room temperature)
A paper substrate (ideal paper thin mouth, 62 g / m ² ) was cut into a width of 50 mm and a length of 100 mm, and an adhesive was applied from one end of the paper to a length of 80 mm with a width of 50 mm and a film thickness of 100 μm. Another paper substrate having the same shape was stacked from above so that the entire surfaces overlap each other, and the substrates were bonded to each other, and this was used as a test piece. After leaving the test piece at room temperature for 70 minutes, the end of the test piece not coated with adhesive was peeled off by pulling 180 ° in the opposite direction at a tensile speed of 300 mm / min using a Tensilon universal tester RTC-1210A. The adhesiveness was evaluated (T-type peel test: JIS K6854). The case where the substrate was broken when the substrate was broken when it was peeled was judged as “adhered”. On the other hand, when the paper base material did not tear and the cohesive failure in which the cured film of the adhesive was torn or the interface failure that peeled between the adhesive and the base material occurred, it was determined that “no adhesion”.
◯: The paper base materials were adhered to each other.
X: The paper base materials did not adhere to each other.

4). Adhesion test (2) (Adhesion during heating)
A test piece was prepared in the same manner as in the adhesion test (1). The test piece was heated at 140 ° C. for 10 seconds immediately after production, and then pulled in the same manner as described above to evaluate adhesiveness.

5. Peel test A test piece was prepared in the same procedure as in the adhesion test (1) and left for 15 minutes. After leaving, it was pulled and peeled in the same manner as described above, and it was evaluated whether or not the paper substrate could be peeled without tearing.
◯: The paper substrate could be peeled off without being broken even after being left for 15 minutes.
X: After leaving for 15 minutes, the paper substrate was torn during peeling and could not be peeled off.

6). Adhesion test (3) (re-stick test)
In the above peeling test, the paper substrates that were peeled once after being left for 15 minutes were pasted together again and left at room temperature (30 ° C.) for 15 minutes. After standing, perform the same T-type peel test as above, and compare the measured value after peeling and reattaching with the measured value before reattaching (when left for 15 minutes after applying the adhesive) did. In Comparative Examples 1, 2 and 4, since peeling was not possible, this reattachment test was not performed.
(Double-circle): Paper base materials adhere | attached and the fall of adhesive strength did not arise compared with before re-sticking.
◯: The paper base materials were bonded to each other, but the adhesive strength was lower than before re-sticking.
X: The paper base materials did not adhere at all.

As shown in Table 1, the adhesives of the examples were excellent in all evaluation results.
In contrast, Comparative Example 1 using a solvent having a standard boiling point in the range of 300 to 400 ° C. but having a low SP value as the oil phase component, and an SP value of 8 to 10 (cal / cm ³ ) ¹ as the oil phase component. ^{/ 2} but is within Comparative example 2 using a low normal boiling point solvent, comparative example using the SP value and high normal boiling point solvent as the oil phase component 3, Comparative example 4 using the low acid value resin In Comparative Example 5 in which the amount of the resin was large and in Comparative Example 6 in which no resin was used, it was confirmed that the effects of the present invention were not achieved. In particular, in Comparative Example 1, the solubility of the solid resin could not be ensured due to the low SP value of the solvent, and the release of the solid resin from the solvent (precipitation of the solid resin) occurred as a result. It is thought that the result of the peel test was poor. On the other hand, in Comparative Example 2, since the boiling point of the solvent was low and the solvent was likely to be scattered, it was considered that the results of the standing drying property and the peel test were poor. In Comparative Example 3, since the boiling point of the solvent is high, the drying property is good (difficult to dry), but the SP value of the solvent is high and the water-soluble polymer is easily dissolved or swollen, so that the adhesive strength is reduced and the emulsion It is thought that the stability of was also impaired.

Claims (3)

It consists of an oil phase and an aqueous phase,
The aqueous phase includes a water-soluble polymer,
The oil phase contains a solvent having a normal boiling point of 300 ° C. or more and 400 ° C. or less and an SP value of 8 to 10 (cal / cm ³ ) ^1/2 , and
The oil phase is a water-in-oil emulsion adhesive containing 2 to 6% by mass of a resin having an acid value of 11 to 100 based on the total amount of the adhesive, which is solid at 30 ° C.   The water-in-oil emulsion adhesive according to claim 1, wherein the content of the resin is 3 to 5 mass% with respect to the total amount of the adhesive.   The water-in-oil emulsion adhesive according to claim 1 or 2, wherein the water-soluble polymer contains polyvinyl alcohol.