WO2018198961A1 - Particulate adhesive and production method therefor - Google Patents

Abstract

This particulate adhesive includes a core comprising an adhesive composition and a shell comprising solid particles. In the particulate adhesive, a constant A represented by formula (I) and indicating the state in which the core is coated by the solid particles is in the range of 0.001 to 0.004.

Description

Granular adhesive and method for producing the same

The present invention relates to a granular adhesive and a method for producing the same.

Generally, adhesives are classified into dry-solid adhesives, chemically-reactive adhesives, hot-melt adhesives, and pressure-sensitive adhesives depending on the solidification method. A dry-solidifying adhesive is one that cures by evaporation of water or a solvent in the adhesive. A chemically reactive adhesive is one that cures by a chemical reaction of a liquid compound. Chemically reactive adhesives include those that cure by the reaction between the main agent and the curing agent, those that cure by the reaction between the main agent and the moisture (moisture) on the surface of the substrate, and those that cure by blocking air. And those that are cured by irradiation with ultraviolet rays. A hot-melt adhesive is solid at room temperature, but becomes liquid when heated, and is fixed by cooling it. A pressure-sensitive adhesive maintains strength with an adherend due to the adhesiveness of the adhesive.

Since the dry-solidifying adhesive and the chemically reactive adhesive are liquids, they could not be touched by people during handling. Although the hot melt adhesive can be touched by a person during handling, it requires heating at the time of bonding, so a heat source is required, and the adherend is required to have heat resistance. The pressure-sensitive adhesive can also be touched at the time of handling, but once it is touched by a person, the adhesiveness is lowered, and a supporting base material is necessary for use in a tape form.

There has been a demand for an adhesive that is different from such a conventional adhesive and has excellent handling. International Publication No. 2015/129903 (Patent Document 1) discloses an adhesive that does not have an adhesive force before applying a stress and develops an adhesive force after applying the stress.

International Publication No. 2015/129903

An object of the present invention is to provide an adhesive that is excellent in handling.

The present invention provides the following granular adhesive, granular adhesive aggregate, and method for producing the granular adhesive.
[1] A granular adhesive comprising a core and a shell covering the core,
The core comprises an adhesive composition;
The shell includes solid particles;
The granular adhesive whose constant A showing the coating state of the said solid particle with respect to the said core shown by following formula (I) is 0.001-0.004.

[Wherein ρ _L represents the specific gravity [g / cm ³ ] of the core,
D _L denotes the particle diameter [cm] of said core,
W _a represents a ratio a / b of the total mass a [g] of the solid particles to the mass b [g] of the core;
ρ _C represents the specific gravity [g / cm ³ ] of the solid particles. ]
[2] The _{D L} is 5cm or less than 0.01 cm, particulate adhesive according to [1].
[3] The number-average particle diameter _{D C} of the solid particles, 1 × ¹⁰ -6 cm to 5 × is ¹⁰ -2 cm or less, the particulate adhesive according to [1] or [2].
[4] The granular adhesive according to any one of [1] to [3], wherein an adhesive force is expressed by applying stress.
[5] A granular adhesive assembly including two or more granular adhesives including a core and a shell covering the core,
A granular adhesive aggregate, wherein at least one of the granular adhesives is the granular adhesive according to any one of [1] to [4].
[6] A method for producing a granular adhesive according to any one of [1] to [4],
A coating step of coating the outer surface of the core precursor for forming the core with the solid particles to obtain coated particles;
A method for producing a granular adhesive, comprising: a coating state adjusting step of changing a coating state of the coated particles.
[7] The method for producing a granular adhesive according to [6], wherein the covering state adjusting step changes the covering state so that the amount of the solid particles contained in the covering particles is reduced.
[8] The coating state adjusting step includes at least one of a step of bringing a liquid containing water into contact with the coated particle, a step of bringing a solid into contact with the coated particle, and a gas contacting step of bringing a gas into contact with the coated particle. The method for producing a granular adhesive according to [6] or [7], which is one.
[9] The method for producing a granular adhesive according to any one of [6] to [8], further comprising a drying step of drying the coated particles.

The granular adhesive of the present invention is easy to express adhesive force by applying stress to the granular adhesive, and even when stored in a storage container etc., the granular adhesive is difficult to adhere to the storage container etc. Excellent.

It is a schematic diagram which shows an example of the granular adhesive agent of this invention.

[Granular adhesive]
The granular adhesive includes a core and a shell covering the core. The core includes an adhesive composition and the shell includes solid particles. The granular adhesive can usually be spherical or flat spherical in the atmosphere. However, when the particle size is relatively small, the granular adhesive can be non-spherical. The granular adhesive has solid particles having no adhesive force on the outer surface of the core. Therefore, when the shell collapses by applying a predetermined stress, the adhesive composition contained in the core is released to the outside of the shell, and the adhesive force by the adhesive composition is expressed.

In the present specification, the outer surface of the core means the outermost surface of the core, that is, a critical surface with air, and may be simply referred to as “surface” in the present specification.

In the granular adhesive, the constant A representing the coating state of the solid particles on the core in the granular adhesive represented by the following formula (I) is 0.001 or more and 0.004 or less. In addition, following formula (I) is a calculation formula obtained by applying the calculation formula of the total cross-sectional area of the solid particle with respect to the surface area of a core.

[Wherein ρ _L represents the specific gravity [g / cm ³ ] of the core,
D _L represents the particle diameter [cm] of the core,
W _a represents the ratio a / b of the total mass a [g] of the solid particles to the mass b [g] of the core,
ρ _C represents the specific gravity [g / cm ³ ] of the solid particles. ]
The constant A is 0.001 or more, preferably 0.0011 or more, more preferably 0.0013 or more, further preferably 0.0015 or more, and 0.004 or less, preferably Is 0.0038 or less, more preferably 0.0036 or less.

When the constant A is less than 0.001, the adhesive composition contained in the core is easily released to the outside of the shell when the shell is collapsed by applying a predetermined stress to the granular adhesive. As a result, when the granular adhesive is stored in a storage container or the like, the granular adhesive adheres to the storage container or the like during storage of the granular adhesive aggregate containing two or more granular adhesives described later. It tends to decrease the storage stability of the granular adhesive. On the other hand, when the constant A exceeds 0.004, it is difficult for the adhesive composition contained in the core to be released to the outside of the shell when the shell is collapsed by applying a predetermined stress to the granular adhesive. As a result, the adhesive force that appears when stress is first applied to the granular adhesive tends to be small.

FIG. 1 is a schematic view showing an example of a state in which the granular adhesive 1 is placed on a table. In FIG. 1, w represents the maximum width of the granular adhesive, k represents the ground contact width, and h represents the height. The maximum width w of the granular adhesive 1 is preferably 100 μm or more, more preferably 500 μm or more, further preferably 1 mm or more, preferably 50 mm or less, more preferably 30 mm or less, More preferably, it is 20 mm or less, Most preferably, it is 10 mm or less.

It means that the smaller the ground contact width k and the smaller the difference between the maximum width w and the height h, the closer the granular adhesive 1 after being placed on the adherend is spherical. These values adjust the type, shape and size of the solid particles constituting the shell, the viscosity of the core, the contact angle of the substance forming the core with respect to the solid particles constituting the shell, the average thickness of the shell, etc. Can be controlled. The ground contact width k and the height h may be adjusted as appropriate. However, the larger the ground contact width k, the greater the frictional force generated with the adherend surface, and the movement of the granular adhesive 1 on the adherend surface can be suppressed. It is preferable to adjust the ground contact width k according to the assumed material and inclination of the adherend surface. The grounding width k can be set to 1 to 100% of the maximum width w, for example. The maximum width w, the contact width k, and the height h are values measured with a caliper through microscopic observation or the like.

W _a is the ratio a / b of the total mass a [g] of the solid particles to the mass b [g] of the core. W _a is preferably 0.00005 or more, more preferably 0.0001 or more, more preferably 0.0002 or more, preferably 1 or less, more preferably 0.5 or less Yes, more preferably 0.3 or less.

The volume of the granular adhesive 1 is preferably 4 μL or more and 6 mL or less. More preferably, it is 6 μL or more, and more preferably 60 μL or more. Moreover, More preferably, it is 4 mL or less, More preferably, it is 3 mL or less.

〔core〕
The core of the granular adhesive contains an adhesive composition. For example, when the core is the adhesive composition itself, or when the core is a droplet containing the adhesive composition described later, the core is obtained by partially removing water or solvent contained in the droplet. There are cases. The adhesive composition may be a dry-solidifying adhesive, a chemically reactive adhesive, or a pressure-sensitive adhesive. The adhesive composition may be the adhesive itself.

Dry solidified adhesives can be divided into solvent-based adhesives, water-based adhesives, and emulsion-based adhesives. The solvent-based adhesive is a type of adhesive that is solidified by dissolving a polymer in an organic solvent and evaporating the organic solvent. Examples of the polymer include chloroprene rubber, styrene butadiene rubber, nitrile rubber, natural rubber, vinyl chloride resin, vinyl acetate resin, (meth) acrylic resin, urethane resin, and the like. Examples of the organic solvent include toluene, normal hexane, ethyl acetate, methyl ethyl ketone, acetone, methanol, tetrahydrofuran, xylene, cyclohexanone, and the like. In the present specification, “(meth) acryl” represents at least one selected from the group consisting of acryl and methacryl. The same applies to notations such as “(meth) acrylonitrile”.

Water-based adhesive is a type of adhesive that is solidified by dissolving a water-soluble polymer in water and evaporating the water. Examples of the water-soluble polymer include natural polymers such as starch and glue, dextrin, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. The water may be pure water or may contain impurities as much as tap water.

The emulsion adhesive is a type of adhesive in which polymer particles stabilized by an electrostatic stabilizing effect or a steric stabilizing effect are dispersed in a dispersion medium and solidified by evaporating the dispersion medium. Polymers constituting the polymer particles include vinyl acetate resin, (meth) acrylic resin, vinylidene chloride resin, epoxy resin, urethane resin, olefin resin, polyester resin, natural rubber resin, and styrene butadiene. Resin, chloroprene rubber resin and the like. Examples of the dispersion medium include water and an organic solvent, and examples of the organic solvent include the same ones as described above.

A chemical reaction type adhesive is a type of adhesive in which one or more types of adhesive components are solidified by a chemical reaction caused by an external stimulus such as heat or light. Chemically reactive adhesives include epoxy adhesives containing epoxy resins and curing agents, polyurethane adhesives containing polyisocyanates and polyols, urea resin adhesives containing urea and formaldehyde, melamine and formaldehyde. Examples thereof include a melamine resin adhesive and a phenol resin adhesive containing phenol and formaldehyde.

In addition, photocurable epoxy adhesives, (meth) acrylic resin adhesives, anaerobic (meth) acrylic adhesives, and two-component curable (meth) acrylic called SGA (Second generation of acrylic adhesives) A system adhesive, a cyano (meth) acrylate-based moisture-curing adhesive, and the like are also exemplified as the chemically reactive adhesive. The two-component curable adhesive is an adhesive that cures when the main agent and the curing agent come into contact with each other. In the two-pack curable adhesive, the main agent and the curing agent may be included in different granular adhesives, and one granular material is used so that the main agent and the curing agent do not contact each other until stress is applied. You may make it exist separately in the core of an adhesive agent. The chemical reaction type adhesive may contain water or a solvent together with these adhesives, and these adhesives may be dissolved or dispersed in water or an organic solvent. Examples of the organic solvent are the same as those described above.

A pressure-sensitive adhesive expresses adhesive force due to the tackiness of the adhesive, and the pressure-sensitive adhesive usually contains a polymer such as a (meth) acrylic resin, a rubber resin, or a silicone resin. It is. The pressure-sensitive adhesive may contain water or an organic solvent together with these adhesives, and these adhesives may be dissolved or dispersed in water or an organic solvent. Examples of the organic solvent are the same as those described above.

The adhesive composition may contain other components. Other components include metal fine particles, metal oxide fine particles, conductive fine particles, ionic conductive compositions, ionic compounds having organic cations or anions, silane coupling agents, crosslinking catalysts, weathering stabilizers, tackifiers, Examples thereof include plasticizers, softeners, dyes, pigments, fragrances, inorganic fillers, resins other than the above polymers, and light diffusing fine particles such as organic beads.

The particle diameter D _L [cm] of the core is preferably 0.01 cm or more, more preferably 0.1 cm or more, still more preferably 0.5 cm or more, and preferably 5 cm or less. Preferably it is 3 cm or less, More preferably, it is 2 cm or less. If the solid particles forming the shell is inorganic particles, the particle diameter D _L of the core, for example, determining the coverage of the solid particles by ICP emission spectrometry, calculating the particle size of the core on the basis of the coverage It can be determined by the method of measuring, the method of measuring by the procedure described in the examples described later. Furthermore, when solid particles forming the shell is an organic particle such as a polymer, for example, it can be determined particle diameter D _L of the core on the basis of the cross-sectional image of the lyophilized particulate adhesive.

The volume of the core containing the adhesive composition is preferably 3 μL or more and 5 mL or less. More preferably, it is 30 μL or more, and more preferably 50 μL or more. Moreover, More preferably, it is 3 mL or less, More preferably, it is 2 mL or less.

〔shell〕
The granular adhesive shell contains solid particles and covers the core. The shell is preferably formed from an aggregate of solid particles. The shell preferably covers the core without having a gap of 500 μm or more, more preferably covers the core without having a gap of 100 μm or more, and more preferably has a gap of 5 μm or more. Without covering the core. The shell may contain other than solid particles, for example, a liquid residue used in the surface treatment described later. However, the content of solid particles in the shell is preferably 90% by mass or more, and 95% by mass or more. Is more preferable, and 100% by mass is even more preferable.

The number average particle diameter D _C of the solid particles forming the shell is preferably 1 × 10 ⁻⁶ cm (10 nm) or more, more preferably 2 × 10 ⁻⁶ cm (20 nm) or more, preferably It is 5 × 10 ⁻² cm (500 μm) or less, more preferably 3 × 10 ⁻² cm (300 μm) or less, and further preferably 1 × 10 ⁻² cm (100 μm) or less. If the number average particle diameter D _C of the solid particles is within the above range is preferable because the stability of the particulate adhesive is higher in the atmosphere.

The number average particle diameter D _C are those obtained by the equivalent circle diameter determined by microscopy, it can be measured by analyzing the image obtained by the microscope, software for a digital microscope. An example of digital microscope software is the product name “Motic Images Plus 2.2s” manufactured by Shimadzu Rika Co., Ltd. Examples of the microscope include an electron microscope and an optical microscope, and may be appropriately selected depending on the solid particles to be used. What is necessary is just to select the magnification at the time of observation suitably according to the particle diameter of the solid particle to be used. The number average particle diameter D _C of the solid particles, a number-average particle diameter of randomly selected 100 solid particles.

The contact angle of the substance forming the core on the aggregated solid particles is usually 90 ° or more, preferably 100 ° or more, more preferably 110 ° or more, further preferably 120 ° or more, Usually, it is 170 ° or less, and may be 160 ° or less. Having such a contact angle is preferable because the solid particles forming the shell and the core-forming substance can be easily adsorbed and the form stability of the granular adhesive is increased. If the contact angle is less than 90 °, the substance forming the core may permeate into the plurality of solid particles that are the shell material, and it may be difficult to form the granular adhesive. As will be described later, the solid particles preferably include hydrophobic particles having a hydrophobic surface. Although depending on the type of substance forming the core, the contact angle described above can be 90 ° or more by using hydrophobic particles having a hydrophobic surface.

The solid particles are preferably particles that do not have an adhesive force in an atmosphere at a temperature of 30 ° C. More preferably, the particles have no adhesive force in an atmosphere having a temperature of 40 ° C. or lower, more preferably a temperature of 50 ° C. or lower, and still more preferably a temperature of 80 ° C. or lower. In this specification, having no adhesive force means an adhesive force with a tack of 0.02 MPa or less when measured by a probe tack test under the following conditions using a commercially available device. Tack is the maximum stress measured by the probe tack test under the following conditions. As a commercially available apparatus, for example, a probe tack tester with a thermostat (product name “TE-6002”) manufactured by Tester Sangyo Co., Ltd. is available.

<Measurement conditions>
Probe tack tester: Probe tack tester with thermostatic bath Speed at which the adhesive is brought into contact with the probe: 10 mm / sec Contact time: 30 sec Peeling speed: 10 mm / sec The glass transition temperature (Tg) of the solid particles is preferably 40 ° C. or higher More preferably, it is 50 degreeC or more, More preferably, it is 80 degreeC or more. If Tg is lower than the above value, the shell may exhibit adhesive force due to a change in the external environment, which may be unsatisfactory in handling. The softening temperature of the solid particles is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 80 ° C. or higher. If the softening temperature is lower than the above value, the shell may exhibit an adhesive force due to a change in the external environment, and handling may be poor.

The decomposition temperature of the solid particles is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 80 ° C. or higher. When the decomposition temperature is lower than the above value, the granular adhesive may exhibit an adhesive force due to a change in the external environment, resulting in poor handling.

As solid particles, particles such as inorganic particles and organic particles can be used. Inorganic particles include talc, clay, kaolin, silica, hydrotalcite, diatomaceous earth, magnesium carbonate, barium carbonate, calcium sulfate, calcium carbonate, magnesium sulfate, barium sulfate, barium titanate, aluminum hydroxide, magnesium hydroxide, oxidation Calcium, magnesium oxide, titanium oxide, zinc oxide, silicon oxide, alumina, mica, zeolite, glass, zirconia, calcium phosphate, metal (gold, silver, copper, iron), carbon material (carbon nanotube, fullerene, graphene, graphite) Etc. Further, the surface of these inorganic particles may be surface modified with a surface modifier such as a silane coupling agent, a surfactant or the like.

Organic particles include synthetic resin particles and natural product-derived particles. As components of organic particles, homopolymers such as styrene, vinyl ketone, (meth) acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, and glycidyl (meth) acrylate, or two or more types of monomers were polymerized. Copolymer; Fluorine resin such as polytetrafluoroethylene, tetrafluoroethylene-6-propylene copolymer, tetrafluoroethylene-ethylene copolymer, and polyvinylidene fluoride; melamine resin; urea resin; polyethylene Polypropylene, polydimethylsiloxane polymer, polyester, polyamide, and the like. Further, the surface of these organic particles may be surface modified with a surface modifier such as a silane coupling agent, a surfactant or the like. The Tg of the resin can be adjusted by polymerization conditions such as the monomer ratio. Examples of the natural product-derived particles include plant spores, pollen, or natural wax-derived particles. Further, the surface of these particles may be surface modified with a surface modifier such as a silane coupling agent, a surfactant or the like.

The solid particles may be a combination of two or more types of particles. Examples of the combination include a combination of two or more kinds of particles having different materials, a combination of two or more kinds of particles having the same material and different particle size distribution, and the like.

The solid particles are preferably hydrophobic particles having a hydrophobic surface. If the surface is hydrophobic, it tends to cover the entire surface of the core precursor described later, and a granular adhesive can be easily produced. Hydrophilic particles having a hydrophilic surface can be made hydrophobic by subjecting the surface to a hydrophobic treatment.

Among the above, the solid particles are preferably silica, lycopodium, polytetrafluoroethylene, or calcium carbonate particles that have been hydrophobized. Such solid particles can be obtained from the market. Commercially available products include silica particles (“RX-300” and “RY-300” manufactured by Nippon Aerosil Co., Ltd.), calcium carbonate particles (manufactured by Shiraishi Kogyo Co., Ltd., hydrophobized), polytetrafluoroethylene ( Sigma Aldrich Japan Co., Ltd.), silicone particles (“Tospearl 2000B”, “Tospearl 1110A”, “Tospearl 145A”, “Tospearl 150KA” manufactured by Momentive) and the like.

The average thickness of the shell is preferably 2 mm or less, more preferably 10 nm or more and 500 μm or less, and further preferably 100 nm or more and 500 μm or less. Such a range is preferable because the shape stability of the granular adhesive is high and the shell can be collapsed by applying an appropriate stress. Here, the collapse of the shell means that the adhesive composition contained in the core is released to the outside of the shell due to the stress applied to the granular adhesive. The average thickness of the shell is determined by dividing the granular adhesive at a temperature equal to or lower than the glass transition temperature of the adhesive composition forming the core, and observing the cross section with an electron microscope (transmission electron microscope, scanning electron microscope). The thickness of the shell is measured at 10 points, and the number is averaged. When the granular adhesive is too large, it can be measured by preparing an ultrathin section.

[Granular adhesive aggregate]
The granular adhesive aggregate includes two or more granular adhesives including a core and a shell covering the core (the upper limit is not particularly limited, for example, 100), and the constant A is 0.001 or more and 0.004. One or more of the following granular adhesives (hereinafter sometimes referred to as “specific granular adhesives”) are included. Although content of the specific granular adhesive agent contained in a granular adhesive aggregate is not specifically limited, Preferably it is 50 mass% or more with respect to the total amount of a granular adhesive aggregate, More preferably, it is 70 mass% or more. More preferably, it is 90% by mass or more, and most preferably 100% by mass.

When the granular adhesive aggregate includes two or more specific granular adhesives, the constant A of the two or more specific granular adhesives may be the same or different from each other. Further, the sizes of the two or more specific granular adhesives may be the same or different from each other.

[Production method of granular adhesive]
A method for producing a granular adhesive having a constant A of 0.001 or more and 0.004 or less includes a coating step of coating the outer surface of a core precursor for forming a core with solid particles to obtain coated particles; And a covering state adjusting step for changing the covering state of the substrate. The core precursor is for forming a core of a granular adhesive, and is, for example, a granular molded product obtained by molding droplets containing the adhesive composition or an adhesive composition into a granular shape. When manufacturing a granular adhesive, in order to adjust the amount (adhesion amount) of solid particles of the coated particles obtained in the coating step, a coating state adjusting step for changing the coating state of the coated particles can be provided. Moreover, you may provide the drying process which dries a covering particle.

[Coating process]
In the coating step, for example, the outer surface of the core precursor is solidified by bringing solid particles into contact with the core precursor, which is a droplet including the adhesive composition, a granular molded product obtained by molding the adhesive composition into a granular shape, or the like. Coated particles can be obtained by coating with particles.

When the core precursor is a droplet containing an adhesive composition, the adhesive composition may be used as it is, or an adhesive composition dissolved in water or a solvent, or an adhesive. What dispersed the composition in water or a solvent may be used, and what diluted the adhesive composition with water or a solvent may be used. For the droplets of the adhesive composition containing the pressure-sensitive adhesive, those obtained by dissolving or dispersing the pressure-sensitive adhesive in water or a solvent are usually used. Examples of the solvent include organic solvents, and examples thereof include the same ones as described above.

The solid content concentration of the droplet containing the adhesive composition when contacting the solid particles is usually 5 to 100% by mass, preferably 10 to 80% by mass, more preferably 20 to 70% by mass. More preferably, it is 40 to 60% by mass. It is preferable that the solid content concentration is within such a range because the granular adhesive can be easily produced. In this specification, solid content concentration means the density | concentration of components other than a solvent and water contained in the droplet containing an adhesive composition.

When the core precursor is a granular molded product obtained by molding the adhesive composition in a granular form, the adhesive composition may be molded into a granular form as it is, or a small amount of water is used to facilitate the molding of the adhesive composition. Or you may add a solvent and shape | mold into a granule. Examples of the solvent include organic solvents, and examples thereof include the same ones as described above.

The size of the core precursor (core volume) is preferably 3 μL or more and 5 mL or less. More preferably, it is 30 μL or more, and more preferably 50 μL or more. Moreover, More preferably, it is 3 mL or less, More preferably, it is 2 mL or less. By adjusting the size of the core precursor, the particle diameter of the granular adhesive can be adjusted.

As a method of bringing the core precursor into contact with the solid particles, the core precursor may be sprayed on the aggregate of solid particles by spraying, or may be dropped or placed. The entire surface of the core precursor is preferably coated with the solid particles by contacting the core precursor with the solid particles. Usually, the entire surface of the core precursor is formed by rolling the core precursor on the solid particles. Coated with solid particles. Alternatively, the core precursor and the solid particles may be mixed with each other using a mixer or the like to contact each other, and the periphery of the core precursor may be coated with the solid particles.

[Coating condition adjustment process]
In the covering state adjusting step, the covering state of the covering particles is changed, and thereby the amount of solid particles (attachment amount) of the covering particles obtained in the covering step can be adjusted. Therefore, by providing the covering state adjusting step, the constant A represented by the formula (I) of the granular adhesive can be adjusted to a desired value.

In the coating state adjustment step, the coating state may be changed so that the amount of solid particles contained in the coated particles is reduced or increased, and the coating state is adjusted so that the solid particles adhere more uniformly to the outer surface of the core precursor. It may be changed. Examples of the coating state adjustment step include a liquid contact step in which a liquid containing water is brought into contact with the coated particle, a solid contact step in which a solid is brought into contact with the coated particle, a gas contact step in which a gas is brought into contact with the coated particle, and the coated particle is sieved. Steps to be applied, a combination of these steps, and the like may be included, and after these steps, a step of bringing them into contact with the solid particles again may be provided to adjust the amount of the solid particles and the uniformity of the adhesion state of the solid particles. .

Examples of the liquid containing water that is brought into contact with the coated particles in the liquid contact step of the coating state adjusting step include water, an organic solvent miscible with water, and a detergent containing water. The water may be pure water, may contain impurities as much as tap water, and may be ion exchange water or the like. Examples of the organic solvent miscible with water include methanol, ethanol, propanol, isopropanol, tert-butyl alcohol, ethylene glycol, dimethyloxyethane, tetrahydrofuran, acetone, diethyl ether, and ethyl acetate. Examples of the detergent containing water include a commercially available liquid detergent, a commercially available powder detergent or a solid detergent added to water, and a neutral detergent is preferably used.

The method of bringing the coated particles into contact with the liquid containing water includes the method of immersing the coated particles in the liquid containing water, the method of stirring the coated particles in the liquid containing water, and the liquid containing water being sprinkled over the coated particles. Methods, combinations thereof, and the like. When the coated particles are brought into contact with the liquid containing water, the contact time between the liquid containing water and the coated particles, or the strength of contact between the fluid containing water and the coated particles (the stirring time, the stirring The covering state of the granular adhesive can be adjusted by adjusting the size, the flow rate of liquid including water, the flow velocity, and the like. The temperature of the liquid containing water is preferably 5 to 90 ° C, more preferably 10 to 70 ° C. The time for contacting the liquid containing water and the coated particles is preferably 1 sec to 5 min, and more preferably 10 sec to 1 min.

When the liquid contact process is performed, it is preferable to perform a drying process immediately after the liquid contact process. About the specific method of a drying process, the method similar to the drying process mentioned later is employable.

Examples of the solid to be brought into contact with the coated particles in the solid contact step of the coating state adjusting step include materials having flexibility such as cloth, cotton, paper and the like. The coated state of the coated particles can be adjusted by moving the coated particles on these solids or rubbing the surface of the coated particles with these solids.

In the gas contact step of the coating state adjustment step, examples of the method of bringing the gas into contact with the coated particles include a method of spraying a gas with an air gun or the like. What does not change the chemical and physical properties of the solid particles may be used. The gas may be warm air, hot air, or low-humidity air. The covering state of the granular adhesive can be adjusted by adjusting the pressure of the gas sprayed onto the coated particles, the spraying speed of the gas, and the like.

When the coated particles are sieved in the coating state adjusting step, the sieve to be used may be selected according to the size of the coated particles and the size of the solid particles. When the coated particles are sieved, one coated particle may be sieved or a plurality of coated particles may be sieved. The covering state of the granular adhesive can be adjusted by adjusting the time for sieving, the magnitude of vibration of the sieve, and the like.

In the covering state adjusting step, it is preferable to change the covering state so that the amount of solid particles contained in the covering particle is reduced. From this viewpoint, it is preferable to perform a liquid contact step or a solid contact step. Among these, the liquid contact step can efficiently reduce the amount of solid particles contained in the coated particles, and the amount of solid particles contained in the coated particles can be more efficiently reduced by using a detergent.

[Drying process]
The drying step is a step of drying the coated particles obtained in the coating step. When the core precursor contains a solvent or water, it is preferably dried. The drying step is a step after the coating step, and is preferably performed before the coating state adjustment step. As used herein, “drying coated particles” means removing water or solvent from a core precursor covered with solid particles. Water or the solvent may be completely removed, but may remain as long as the adhesiveness of the adhesive is not lowered. As a drying method, a method of standing and drying at a temperature at which the chemical and physical properties of the adhesive composition and solid particles do not change; a method of exposing to hot air, hot air or low humidity; a method of vacuum drying; freezing A method of drying; a method of irradiating infrared rays, far infrared rays, electron beams or the like, a combination thereof, and the like. The temperature for removing the liquid containing water is preferably 10 to 200 ° C, more preferably 20 to 100 ° C.

The solid content concentration of the adhesive composition contained in the granular adhesive after drying is, for example, 10 to 100% by mass, preferably 50 to 100% by mass, more preferably 80 to 100% by mass, Preferably, it is 90 to 100% by mass.

[How to use granular adhesive]
The granular adhesive can be used as the granular adhesive alone or as a granular adhesive aggregate containing two or more granular adhesives. By applying a predetermined stress, the granular adhesive can collapse the shell and release the adhesive composition contained in the core to the outside of the shell. The magnitude of the predetermined stress is appropriately selected according to the use of the granular adhesive and its general handling. The magnitude of the predetermined stress is the kind, shape and size of solid particles constituting the shell, the viscosity of the core, the contact angle of the substance forming the core with respect to the solid particles constituting the shell, the average thickness of the shell, etc. Can be controlled by adjusting.

The predetermined stress is preferably large enough to be given by crushing with a human finger. Specifically, it is preferably 1 to 1000 kN / m ² , more preferably 5 to 200 kN / m ² , and still more preferably 5 to 100 kN / m ² . If it is this range, after arrange | positioning a granular adhesive agent to a to-be-adhered material, an adhesive composition can be easily discharge | released to the outer side of a shell by giving a stress. Moreover, the handleability of a granular adhesive agent also becomes favorable. If the predetermined stress is too small, the adhesive composition may be unintentionally released to the outside of the shell. Therefore, it is preferable that the granular adhesive does not cause collapse of the shell at a stress of less than 1 kN / m ² . When applying stress to the granular adhesive, the adhesive composition is easily released to the outside of the shell.

Granular adhesive can be used by sandwiching it between adherends. For example, a granular adhesive is sandwiched between one adherend (hereinafter referred to as adherend A) and another adherend (hereinafter referred to as adherend B), and the adherends are pressed together. Thus, the adherend A and the adherend B can be bonded by applying stress to the granular adhesive. Here, the adherend A and the adherend B may be the same or different.

The granular adhesive is, for example, sandwiched between the adherend A and the release material, pressed against the adherend A and the release material, and applied stress to the granular adhesive. The adhesive composition can be released on the surface of the dressing A. Thereafter, the release material can be removed. After removing the release material, the adherend B may be adhered.

The granular adhesive or the granular adhesive aggregate is developed into a plane shape, and stress is applied to the granular adhesive, thereby releasing the adhesive composition to the outside of the shell to form a film containing the adhesive composition. You can also Here, the granular adhesive or the granular adhesive aggregate is usually disposed on a planar adherend. Stress is usually applied through a release material, which is then removed.

The adherend B may be further adhered on the film. The coating film can also be formed by curing the film. For example, the surface of the adherend can be coated with a cured product of the adhesive composition.

The granular adhesive can be used by being crushed as described above, but after releasing the adhesive composition contained in the core to the outside of the shell by applying pressure to the granular adhesive and kneading, or the like, or The core and the shell may be sufficiently mixed and then disposed on the adherend.

[Use of granular adhesive]
The granular adhesive is a granular adhesive alone or as a granular adhesive aggregate containing two or more granular adhesives, an adhesive for automobiles, an adhesive for building materials, fitting of bearings, fixing of piping, prevention of loosening of screws. It can be used for fixing gears and propellers, assembling furniture, toppling prevention members (earthquake countermeasures), temporary fixing materials for exhibits, temporary fixing materials for clothes, stationery, and the like.

Hereinafter, the present invention will be described with reference to examples. Unless otherwise specified, “%” and “parts” in Examples and Comparative Examples are “% by mass” and “parts by mass”.

[Measurement of particle diameter _{D L} of the core]
One granular adhesive was weighed. Sulfuric acid was added to the weighed granular adhesive, carbonized with a hot plate, and then incinerated with an electric furnace to obtain an incinerated product. Water and hydrochloric acid were added to the obtained ashed product and dissolved by heating, and the Ca concentration was measured by ICP emission spectroscopic analysis. Using a calibration curve prepared with a Ca standard solution with a known concentration, quantitative analysis of the Ca content was performed. The mass of solid particles (CaCO ₃ ) and the mass of the core were calculated from the Ca content obtained by quantitative analysis and the mass of the granular adhesive measured above. Using the specific gravity of the core as measured by the method described below, the core was calculated particle diameter D _L of the core assuming a perfect sphere.

[Measurement of specific gravity ρ _L of core]
Only the adhesive composition forming the core of the granular adhesive was placed in a Teflon (registered trademark) petri dish and dried at 45 ° C. for 3 days to produce an adhesive film which is a film of the adhesive composition. A coating film having a thickness of 2 mm was cut into 5 cm ² squares, the mass of the cut coating film was measured, and the mass of 1 cm ² squares was calculated. After laminating the coating film on both sides of the adhesive film prepared above, the film was cut into 1 cm ² squares to obtain a laminated film, and its mass was measured. The mass of the adhesive film was calculated from the mass of the cut film for covering and the mass of the laminated film. Further, the cross section of the laminated film was observed at 50 times using a digital microscope (VHX-2000), and the thickness of the adhesive film was calculated from the observed image. The specific gravity ρ _L of the core was calculated from the area of the adhesive film and the mass and thickness of the adhesive film calculated above.

[Specific gravity of solid particles ρ _C ]
The true specific gravity of calcium carbonate was used.

[Calculation of constant A]
The ratio of the CaCO ₃ weight was calculated in the measurement of the particle diameter D _L of the core] and based on the core weight, W a _(total weight of solid particles to the mass b [g] of the core in the particulate adhesive a [g] a / b) was calculated. The constant A was calculated using the calculated W _a , the core particle diameter D _L obtained by the above measurement, the core specific gravity ρ _L , and the solid particle specific gravity ρ _C.

[Peel test]
0.5 g of granular adhesive (granular adhesive aggregate) was placed on a wallpaper 2 cm wide × 7.5 cm long (RH-9613, manufactured by Renon Co., Ltd.). Cover the wallpaper on the side where the granular adhesive aggregate is placed with a size of 20 mm x 20 mm so that it is covered with 2 cm wide x 7.5 cm long coated paper. Thus, a joined sample in which wallpaper and coated paper were bonded together was obtained. About the obtained bonded sample, the wallpaper and the coated paper are pulled at 300 mm / min so as to be opposite to each other along the longitudinal direction of the wallpaper, and the strength when peeling occurs between the wallpaper and the coated paper is peeled off. The strength was [N]. The peel strength exceeding 0N was judged as good, and the peel strength was judged as poor.

[Initial storage stability test]
A cylindrical glass bottle with a bottom area of 23 cm ² (manufactured by Maruemu Co., Ltd., screw tube No. 5) was charged with 6 granular adhesives, and the lid on the top side of the glass bottle was immediately below. Inverted and held for 5 sec. During this holding time, the number of granular adhesives that adhered to the bottom of the glass bottle and did not fall to the lid side was counted to evaluate the initial storage stability. The case where the number of the granular adhesives adhered to the bottom surface was 1 or less was evaluated as good, the case of 2 or 3 was slightly good, and the case of 4 or more was evaluated as bad.

[Preservation test after durability test]
The granular adhesive was put in a glass bottle similar to the glass bottle used in the initial storage test, and left to stand in an environment of a temperature of 60 ° C. and a humidity of 90% for 1 hour to conduct a durability test. After that, the granular adhesive in the glass bottle is held upside down for 5 seconds so that the lid on the top side of the glass bottle is down, and the durability test is performed according to the same procedure and the same evaluation criteria as the initial shelf life test. Later storage was evaluated.

[Measurement of number average molecular weight Mn]
The number average molecular weight Mn (standard polystyrene conversion value by gel permeation chromatography (GPC)) of the polybutyl acrylate emulsion was measured. The number average molecular weight Mn was measured using the GPC method under the following conditions.

(conditions)
Equipment: HLC-8120GPC (manufactured by Tosoh Corporation)
Column: PLgel mixed-C + GuardColumn
Column temperature: 40 ° C
Mobile phase: DMF (30 mM LiBr, 10 mM H ₃ PO ₄ )
Flow rate: 1.0 mL / min
Test solution solid content concentration: 0.5 mg / mL (converted to solid content)
Injection volume: 100 μL
Detector: RI-8020 / UV-8020 (254 nm)
Calibration standard: TSK STANDARD POLYSTYRENE (F-128, F-40, F-10, F-4, F-1, A-5000 (manufactured by Tosoh Corporation)).

[Measurement of acid value AV]
0.5 g of polybutyl acrylate was dissolved in 100 mL of acetone, and a few drops of phenolphthalein solution was added as an indicator. Then, titration was performed with a 0.1 mol / L potassium hydroxide ethanol aqueous solution (amount of chemical formula of potassium hydroxide: 56.11 × 0.1 = 5.611), and the end point was reached when the light red color of the indicator lasted for 30 seconds. The amount [mL] of the potassium hydroxide ethanol aqueous solution used for the titration was measured, and the acid value AV was calculated based on the following formula.

AV = (B × f × 5.611) / S
(The symbols in the formula represent the following.

AV: Acid value B: Amount of 0.1 mol / L potassium hydroxide ethanol aqueous solution used for titration [mL]
f: Factor of 0.1 mol / L potassium hydroxide ethanol aqueous solution S: Mass of polybutyl acrylate [g])
[Example 1]
Solid particles, number average particle diameter _{D C} is 80nm of calcium carbonate particles: Using the (hydrophobic treated, Hakuenka CCR-S (Dc 80nm), Shiraishi Kogyo Co., Ltd.) was spread thinly on a petri dish. The calcium carbonate particles did not have adhesive strength at a temperature of 80 ° C. or lower. Prepare an emulsion of polybutyl acrylate (main component: butyl acrylate, number average molecular weight Mn: 78000, acid value: 7 mg / g, solid content: 50.7%) as an adhesive composition. Then, 50 drops were dropped on the calcium carbonate particles spread thinly on the petri dish. The number average molecular weight Mn and the acid value were measured by the measurement methods described above. The 50 emulsion droplets (core precursor) were rolled on the calcium carbonate particles for 30 seconds to obtain 50 coated particles in which the entire outer surface of the emulsion droplets was covered with calcium carbonate particles. . The coated particles were dried at a temperature of 45 ° C. for 12 hours to remove water. The coating particles subjected to the drying step are subjected to a coating adjustment step in which a sieve operation is performed by reciprocating about 30 times for 30 seconds using a mesh basket (manufactured by SUS304, φ1.5 mm mesh). Fifty spherical granular adhesives were obtained in which the entire outer surface of the contained core was covered with calcium carbonate particles.

An arbitrary number of granular adhesives are selected from the obtained 50 granular adhesives, and for each granular adhesive, the specific gravity ρ _C of the solid particles, the particle diameter D _{L of the} core, the specific gravity ρ _L , and the specific gravity ρ _{C of the} solid particles Was measured, a constant A was calculated, and an average value was calculated for each value. In addition, it confirmed that the constant A as an average value was substantially the same as the constant A obtained about one granular adhesive.

In addition, a peel test, an initial storage stability test, and a storage stability test after an endurance test were performed using the obtained granular adhesive. The results are shown in Table 1.

[Examples 2 to 6, Comparative Examples 1 to 3]
As solid particles, calcium carbonate particles having a number average particle diameter D _C shown in Table 1 (hydrophobized, manufactured by Shiraishi Kogyo Co., Ltd., Hakucho Hana CCR-S (D _C : 80 nm), Vigot-10 (D _C : 100 nm) ) And Vigot-15 (D _C : 150 nm)), and 50 granular adhesives were obtained in the same manner as in Example 1 except that the conditions of the coating state adjustment step shown in Table 1 were used. In addition, each description of the covering state adjustment process in Table 1 represents the following matters. Further, in Comparative Example 1, the covering state adjusting step is not performed, and when “water washing” or “detergent cleaning” is performed as the covering state adjusting step, a drying process is performed at a temperature of 45 ° C. for 12 hours after the covering state adjusting step. It was.
·"sieve"
: As described in Example 1, the sieve operation is performed by reciprocating about 30 times for 30 seconds using a mesh basket (manufactured by SUS304, mesh of φ1.5 mm).
・ "Cotton wipe" (solid contact process)
: Place a granular adhesive on cotton (Bencott M-3II, manufactured by Ozu Sangyo Co., Ltd.), and further cover the same cotton as the above cotton.
・ "Washing" (liquid contact process)
: Place the granular adhesive on a mesh basket (made of SUS304, mesh of φ1.5 mm), and wash with running tap water with a flow rate of 2.15 m / sec for 1 min. In Table 1, it is described as “tap water”.
・ "Detergent cleaning" (liquid contact process)
: Place the granular adhesive on a mesh basket (SUS304, φ1.5 mm mesh), apply 5 g of detergent (Mama Lemon, manufactured by LION Co., Ltd.), and wash with running tap water at a flow rate of 2.15 m / sec for 1 min.

For the obtained granular adhesive, the average constant A was calculated in the same manner as in Example 1, and using the obtained granular adhesive, a peel test, an initial storage stability test, and a storage stability test after an endurance test were performed. went. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 6 where the constant A is 0.001 or more and 0.004 or less, the peel strength of the peel test is good, and the initial storage stability test and the storage stability test after the durability test. The test result was good or slightly good. On the other hand, in Comparative Example 1 where the constant A exceeded 0.004, the peel strength in the peel test was poor. Further, in Comparative Examples 2 and 3 in which the constant A was less than 0.001, the test results were poor in the initial storage stability test and the storage stability test after the durability test.

Claims (9)

1. A granular adhesive comprising a core and a shell covering the core,
   The core comprises an adhesive composition;
   The shell includes solid particles;
   The granular adhesive whose constant A showing the coating state of the said solid particle with respect to the said core shown by following formula (I) is 0.001-0.004.
   

   

   
   [Wherein ρ _L represents the specific gravity [g / cm ³ ] of the core,
   D _L denotes the particle diameter [cm] of said core,
   W _a represents a ratio a / b of the total mass a [g] of the solid particles to the mass b [g] of the core;
   ρ _C represents the specific gravity [g / cm ³ ] of the solid particles. ]
2. Wherein _{D L} is 5cm or less than 0.01 cm, particulate adhesive according to claim 1.
3. The number average particle diameter _{D C} is, 1 × ¹⁰ -6 cm to 5 × is ¹⁰ -2 cm or less, the particulate adhesive according to claim 1 or 2 of the solid particles.
4. The granular adhesive according to any one of claims 1 to 3, wherein an adhesive force is expressed by applying a stress.
5. A granular adhesive assembly including two or more granular adhesives including a core and a shell covering the core,
   A granular adhesive aggregate, wherein at least one of the granular adhesives is the granular adhesive according to any one of claims 1 to 4.
6. A method for producing a granular adhesive according to any one of claims 1 to 4,
   A coating step of coating the outer surface of the core precursor for forming the core with the solid particles to obtain coated particles;
   A method for producing a granular adhesive, comprising: a coating state adjusting step of changing a coating state of the coated particles.
7. The method for producing a granular adhesive according to claim 6, wherein the covering state adjusting step changes the covering state so that the amount of the solid particles contained in the covering particles is reduced.
8. The coating state adjusting step includes a liquid contact step in which a liquid containing water is brought into contact with the coated particle, a solid contact step in which a solid is brought into contact with the coated particle, and a gas contact step in which a gas is brought into contact with the coated particle. The manufacturing method of the granular adhesive agent of Claim 6 or 7 which is at least one.
9. The method for producing a granular adhesive according to any one of claims 6 to 8, further comprising a drying step of drying the coated particles.

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