JP5481324B2 - Foam adhesive - Google Patents

Description

  The present invention relates to a foamed adhesive. Specifically, the present invention relates to a foamed adhesive body that can adhere to an adherend by using an adhesive force of a micro suction cup formed by a foam structure.

  Recently, a pressure-sensitive adhesive body utilizing an adsorption force by a micro sucker structure has been proposed (see, for example, Patent Documents 1 and 2).

  The pressure-sensitive adhesive body utilizing the adsorption force by the micro sucker structure is a flexible pressure-sensitive adhesive body having a large number of concave recessed holes on the order of microns, and the concave recessed holes are formed by pressure-bonding the adhesive to the adherend. Adsorbs to the adherend as a sucker.

  For example, in Patent Document 1, a low-elasticity adsorptive foam layer is produced by adding a plasticizer to an acrylic emulsion and causing it to foam. However, the adsorptive foam layer in Patent Document 1 has a problem that heat resistance is low and a problem that a plasticizer must be used. And there exists a problem that the adhesive force of the absorptive foam layer in patent document 1 cannot be said to be enough.

  Moreover, in patent document 2, the acrylic adhesive foam in which the usage-amount of the foaming adjuvant was reduced compared with the past is reported. However, the acrylic adhesive foam in Patent Document 2 has a problem of low flexibility and a problem of low bubble content in the foam. And there exists a problem that the adhesive force of the acrylic adhesive foam in patent document 2 cannot be said to be enough.

Japanese Patent No. 4335835 JP 2009-263542 A

  An object of the present invention is a foamed adhesive body that can adhere to an adherend by using the adhesive force of a micro sucker formed by a foam structure, and can exhibit sufficient adhesive force, has high flexibility, and has high heat resistance. The object is to provide a novel foamed pressure-sensitive adhesive having a high value.

The foamed adhesive body of the present invention is
A foamed pressure-sensitive adhesive comprising a foam having an open-cell structure having through-holes between adjacent spherical bubbles,
The average pore size of the spherical bubbles is less than 20 μm,
The average pore diameter of the through holes is 5 μm or less,
The surface of the foam has a surface opening having an average pore diameter of 20 μm or less,
The normal shear adhesive strength is 1 N / cm ² or more.

  In a preferred embodiment, the foamed adhesive body of the present invention has a 180 ° peel test force of 1 N / 25 mm or less.

  In a preferred embodiment, the foamed adhesive body of the present invention has a 60 ° C. holding force of 0.5 mm or less.

In a preferred embodiment, the foamed adhesive body of the present invention has a 50% compression load of 150 N / cm ² or less.

  In a preferred embodiment, the foamed adhesive body of the present invention has a dimensional change rate of less than ± 5% when stored at 125 ° C. for 22 hours.

In a preferred embodiment, the foam has a density in the ^{0.15g / cm 3 ~0.6g / cm 3} .

  In a preferred embodiment, the foam ratio of the foam is 30% or more.

  According to the present invention, a foamed adhesive body that can adhere to an adherend using the adhesive force of a micro suction cup formed by a foamed structure, can exhibit sufficient adhesive force, has high flexibility, and has high heat resistance. Can provide a novel foamed adhesive.

It is a schematic sectional drawing which shows preferable embodiment of the foaming adhesive body of this invention. It is a schematic sectional drawing which shows another preferable embodiment of the foaming adhesive body of this invention. It is a photograph figure of the surface / cross-section SEM photograph which image | photographed the foaming adhesive body produced in Example 1 from diagonally. It is a photographic view of a cross-sectional SEM photograph of the foamed adhesive body of the present invention, and is a photographic view clearly showing an open cell structure having through holes between adjacent spherical bubbles.

≪ << A. Foam adhesive >>>>
The foamed pressure-sensitive adhesive body of the present invention is a foamed pressure-sensitive adhesive body including a foam having an open-cell structure having through holes between adjacent spherical cells. Typical structures include a foamed adhesive body 100 (FIG. 1) made of the foam 10 and a foamed adhesive body 100 (FIG. 2) including a base material 20 (described later) between the foam 10a and the foam 10b. Can be mentioned. In FIG. 1 and FIG. 2, the release film 30 is provided for protecting the adhesive surface of the foamed adhesive, but the release film may not be provided.

  In the present specification, the “spherical bubble” does not have to be a strict true spherical bubble, and may be, for example, a substantially spherical bubble having a partial strain or a bubble composed of a space having a large strain. .

  The average pore diameter of the spherical bubbles contained in the foam contained in the foamed adhesive of the present invention is less than 20 μm, preferably 15 μm or less, and more preferably 10 μm or less. The lower limit value of the average pore diameter of the spherical bubbles contained in the foam contained in the foamed pressure-sensitive adhesive of the present invention is not particularly limited. For example, it is preferably 0.01 μm, more preferably 0.1 μm, and even more preferably 1 μm. It is. The average pore diameter of the spherical bubbles of the foam contained in the foamed adhesive body of the present invention falls within the above range, so that the average pore diameter of the spherical cells of the foam contained in the foamed adhesive body of the present invention can be precisely controlled to be small. A novel foamed pressure-sensitive adhesive body excellent in flexibility and heat resistance can be provided.

Density of the foam contained in the foamed pressure-sensitive adhesive body of the present invention is preferably ^{0.15g / cm 3 ~0.6g / cm 3} , more preferably 0.15g ^/ cm ³ ~0.5g ^/ cm 3 There, more preferably ^{0.15g / cm 3 ~0.45g / cm 3} , particularly preferably from ^{0.15g / cm 3 ~0.4g / cm 3} . When the density of the foam contained in the foamed adhesive body of the present invention falls within the above range, the range of the density of the foam contained in the foamed adhesive body of the present invention is widely controlled, and the flexibility and heat resistance are improved. An excellent and novel foamed adhesive can be provided.

  The foam contained in the foamed adhesive body of the present invention has an open cell structure having through holes between adjacent spherical cells. This open cell structure may be an open cell structure having through holes between most or all adjacent spherical cells, or may be a semi-independent semi-open cell structure having a relatively small number of through holes. .

  The through-hole which has between adjacent spherical bubbles influences the physical property of a foaming adhesive body. For example, the strength of the foamed adhesive body tends to increase as the average hole diameter of the through holes decreases. FIG. 4 is a photographic view of a cross-sectional SEM photograph of the foamed pressure-sensitive adhesive body of the present invention, and shows a photographic view clearly showing an open cell structure having through holes between adjacent spherical bubbles.

  The average pore diameter of the through holes between adjacent spherical bubbles is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. The lower limit value of the average pore diameter of the through holes between adjacent spherical bubbles is not particularly limited, and is preferably 0.001 μm, and more preferably 0.01 μm, for example. When the average pore diameter of the through-holes between adjacent spherical bubbles is within the above range, a novel foamed pressure-sensitive adhesive having excellent flexibility and heat resistance can be provided.

  The foamed adhesive body of the present invention has a surface opening on the surface. The average pore diameter of the surface opening is 20 μm or less, preferably less than 20 μm, more preferably 15 μm or less, further preferably 10 μm or less, further preferably 5 μm or less, and particularly preferably 4 μm or less. And most preferably 3 μm or less. The lower limit of the average pore diameter of the surface opening is not particularly limited, and is preferably 0.001 μm, and more preferably 0.01 μm, for example. When the foamed adhesive body of the present invention has a surface opening and the average pore diameter of the surface opening is within the above range, the surface opening plays a role of a micro sucker and expresses sufficient adhesive force. It is possible to provide a novel foamed pressure-sensitive adhesive body that can be used, and to provide a novel foamed pressure-sensitive adhesive body having high flexibility and high heat resistance.

The foamed pressure-sensitive adhesive of the present invention has a normal shear adhesive strength of 1 N / cm ² or more, preferably 3 N / cm ² or more, more preferably 5 N / cm ² or more, and further preferably 7 N / cm ^2. Or more, particularly preferably 9 N / cm ² or more, and most preferably 10 N / cm ² or more. When the normal shear adhesive strength of the foamed pressure-sensitive adhesive body of the present invention falls within the above range, the foamed pressure-sensitive adhesive body of the present invention can exhibit a sufficient pressure-sensitive adhesive force.

  The foamed pressure-sensitive adhesive of the present invention has a 180 ° peel test force of preferably 1 N / 25 mm or less, more preferably 0.8 N / 25 mm or less, still more preferably 0.5 N / 25 mm or less, particularly preferably. Is 0.3 N / 25 mm or less. When the 180 ° peel test force of the foamed adhesive body of the present invention falls within the above range, the foamed adhesive body of the present invention can be easily peeled even though the adhesive force is high as described above. An excellent effect can be exhibited.

  The foamed pressure-sensitive adhesive of the present invention has a 60 ° C. holding force of preferably 0.5 mm or less, more preferably 0.4 mm or less, still more preferably 0.3 mm or less, and particularly preferably 0.2 mm or less. It is. When the 60 ° C. holding force of the foamed adhesive body of the present invention falls within the above range, the foamed adhesive body of the present invention can achieve both excellent heat resistance and sufficient adhesive force.

The foamed adhesive of the present invention has a 50% compression load of preferably 150 N / cm ² or less, more preferably 120 N / cm ² or less, still more preferably 100 N / cm ² or less, and particularly preferably 70 N. / Cm ² or less, and most preferably 50 N / cm ² or less. When the 50% compressive load of the foamed adhesive body of the present invention falls within the above range, the foamed adhesive body of the present invention can exhibit excellent flexibility.

  The foamed adhesive body of the present invention has a dimensional change rate of preferably less than ± 5%, more preferably ± 3% or less, and further preferably ± 1% or less when stored at 125 ° C. for 22 hours. . In the foamed adhesive body of the present invention, the dimensional change rate when stored at 125 ° C. for 22 hours is within the above range, whereby the foamed adhesive body of the present invention can have excellent heat resistance.

  The foam contained in the foamed pressure-sensitive adhesive of the present invention has a cell ratio of preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. In the foamed pressure-sensitive adhesive body of the present invention, sufficient foaming strength can be expressed when the foam ratio of the foam contained in the foamed pressure-sensitive adhesive body of the present invention is within the above range, and high flexibility and high heat resistance are also expressed. it can.

The foam material contained in the foamed pressure-sensitive adhesive body of the present invention is a foam having an open cell structure having through-holes between adjacent spherical cells, and the average pore diameter of the spherical cells is less than 20 μm, Any appropriate pore size can be used as long as the average pore size is 5 μm or less, the surface of the foam has an average pore size of 20 μm or less, and the normal shear adhesive strength is 1 N / cm ² or more. Material may be employed.

  The foamed pressure-sensitive adhesive body of the present invention can take any appropriate shape. Practically, preferably, the foamed adhesive body of the present invention is a sheet-like foamed adhesive body sheet. When the foamed pressure-sensitive adhesive body of the present invention is a foamed pressure-sensitive adhesive sheet, the thickness, the long side, and the length of the short side can take any appropriate value.

  The foamed pressure-sensitive adhesive body of the present invention may contain any appropriate base material as long as the effects of the present invention are not impaired. As a form in which the base material is contained in the foamed adhesive body of the present invention, for example, a form in which a layer of the base material is provided inside the foamed adhesive body can be mentioned. Examples of such a substrate include fiber woven fabric, fiber nonwoven fabric, fiber laminated fabric, fiber knitted fabric, resin sheet, metal foil film sheet, and inorganic fiber. Arbitrary appropriate thickness can be employ | adopted for the thickness of a base material according to material and the objective.

  As the fiber woven fabric, a woven fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Further, the fiber woven fabric may be metallic processed by plating or sputtering.

  As a fiber nonwoven fabric, the nonwoven fabric formed from arbitrary appropriate fibers can be employ | adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Moreover, the fiber nonwoven fabric may be metallic-processed by plating, sputtering, etc. More specifically, for example, a spunbond nonwoven fabric can be mentioned.

  As the fiber laminated fabric, a laminated fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. In addition, the fiber laminated fabric may be metallic processed by plating, sputtering, or the like. More specifically, for example, a polyester fiber laminated fabric can be mentioned.

  As a fiber knitted fabric, the knitted fabric formed from arbitrary appropriate fibers can be employ | adopted, for example. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Further, the fiber knitted fabric may be metallically processed by plating or sputtering.

  As the resin sheet, a sheet formed of any appropriate resin can be adopted. An example of such a resin is a thermoplastic resin. The resin sheet may be metallic processed by plating or sputtering.

  As the metal foil film sheet, a sheet formed from any appropriate metal foil film can be adopted.

  Any appropriate inorganic fiber can be adopted as the inorganic fiber. Specific examples of such inorganic fibers include glass fibers, metal fibers, and carbon fibers.

  In the foamed adhesive body of the present invention, when voids are present in the substrate, the same material as the foamed adhesive body may be present in part or all of the voids.

  Only 1 type may be used for a base material and it may use 2 or more types together.

≪≪B. Manufacturing method of foamed adhesive >>>>
The foamed adhesive body of the present invention can be produced by any appropriate method. The foamed pressure-sensitive adhesive body of the present invention can be preferably produced by shaping and polymerizing a W / O emulsion.

  As a method for producing the foamed adhesive body of the present invention, for example, a W / O type emulsion that can be used to obtain a foamed adhesive body of the present invention by continuously supplying a continuous oil phase component and an aqueous phase component to an emulsifier. There is a “continuous method” in which the prepared W / O emulsion is polymerized to produce a water-containing polymer, and then the obtained water-containing polymer is dehydrated. As a method for producing the foamed pressure-sensitive adhesive body of the present invention, for example, an appropriate amount of an aqueous phase component with respect to a continuous oil phase component is charged into an emulsifier, and the aqueous phase component is continuously supplied while stirring. A W / O emulsion that can be used to obtain the foamed pressure-sensitive adhesive of the present invention is prepared, and the resulting W / O emulsion is polymerized to produce a hydrous polymer. The “batch method” is used for dehydration.

  The continuous polymerization method in which the W / O emulsion is continuously polymerized is a preferable method because the production efficiency is high and the effect of shortening the polymerization time and the shortening of the polymerization apparatus can be most effectively utilized.

More specifically, the foamed adhesive of the present invention is preferably
Step (I) of preparing a W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive body of the present invention;
Step (II) of shaping the obtained W / O emulsion,
Polymerizing the shaped W / O emulsion (III);
Step (IV) of dehydrating the obtained hydrous polymer;
It can manufacture with the manufacturing method containing. Here, at least a part of the step (II) for shaping the obtained W / O emulsion and the step (III) for polymerizing the shaped W / O emulsion may be performed simultaneously.

<< B-1. Step for preparing W / O type emulsion (I) >>
The W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive body of the present invention is a W / O type emulsion containing a continuous oil phase component and an aqueous phase component immiscible with the continuous oil phase component. More specifically, the W / O type emulsion is obtained by dispersing an aqueous phase component in a continuous oil phase component.

  The ratio of the water phase component to the continuous oil phase component in the W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive of the present invention takes any appropriate ratio within the range that can form the W / O type emulsion. obtain. The ratio of the water phase component to the continuous oil phase component in the W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive of the present invention is the structural and mechanical properties of the foam obtained by polymerization of the W / O type emulsion. Can be an important factor in determining performance and performance characteristics. Specifically, the ratio of the water phase component to the continuous oil phase component in the W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive body of the present invention is a foam obtained by polymerization of the W / O type emulsion. Can be an important factor in determining the density, bubble size, bubble structure, and dimensions of the wall forming the porous structure.

  The ratio of the aqueous phase component in the W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive of the present invention is preferably 30% by weight, more preferably 40% by weight, and still more preferably as the lower limit. 50% by weight, particularly preferably 55% by weight, and the upper limit is preferably 95% by weight, more preferably 90% by weight, still more preferably 85% by weight, particularly preferably 80% by weight. %. If the ratio of the aqueous phase component in the W / O emulsion that can be used to obtain the foamed pressure-sensitive adhesive of the present invention is within the above range, the effects of the present invention can be sufficiently exhibited.

  The W / O type emulsion that can be used for obtaining the foamed pressure-sensitive adhesive of the present invention may contain any appropriate additive as long as the effects of the present invention are not impaired. Examples of such additives include tackifying resins; talc; calcium carbonate, magnesium carbonate, silicic acid and salts thereof, clay, mica powder, aluminum hydroxide, magnesium hydroxide, zinc white, bentonine, carbon black, Examples thereof include fillers such as silica, alumina, aluminum silicate, acetylene black, and aluminum powder; pigments; dyes; Only one kind of such an additive may be contained, or two or more kinds thereof may be contained.

  Any appropriate method can be adopted as a method for producing a W / O type emulsion that can be used for obtaining the foamed pressure-sensitive adhesive body of the present invention. As a method for producing a W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive body of the present invention, for example, a continuous oil phase component and an aqueous phase component are continuously supplied to an emulsifier to produce a W / O type emulsion. A W / O type emulsion is formed by supplying an appropriate amount of aqueous phase component to the continuous oil phase component in an emulsifier and continuously supplying the aqueous phase component while stirring. The “batch method” is used.

  When producing a W / O type emulsion that can be used to obtain the foamed pressure-sensitive adhesive body of the present invention, as a shearing means for obtaining an emulsion state, for example, a rotor-stator mixer, a homogenizer, a microfluidizer, etc. Application of shearing conditions can be mentioned. In addition, as another shearing means for obtaining an emulsion state, for example, gentle mixing of continuous and dispersed phases by application of low shear conditions using a moving blade mixer or a pin mixer, low stirring conditions using a magnetic stir bar, etc. Can be mentioned.

  Examples of the apparatus for preparing the W / O emulsion by the “continuous method” include a static mixer, a rotor stator mixer, and a pin mixer. More intense agitation may be achieved by increasing the agitation speed or by using an apparatus designed to finely disperse the aqueous phase component in the W / O emulsion by a mixing method.

  Examples of the apparatus for preparing the W / O type emulsion by the “batch method” include manual mixing and shaking, a driven blade mixer, and three propeller mixing blades.

  Arbitrary appropriate methods can be employ | adopted as a method of preparing a continuous oil phase component. As a method for preparing the continuous oil phase component, typically, for example, a mixed syrup containing a hydrophilic polyurethane-based polymer and an ethylenically unsaturated monomer is prepared, and subsequently, a polymerization initiator, It is preferable to prepare a continuous oil phase component by blending a crosslinking agent and any other appropriate components.

  Any appropriate method can be adopted as a method of preparing the hydrophilic polyurethane-based polymer. A typical method for preparing a hydrophilic polyurethane-based polymer is, for example, by reacting polyoxyethylene polyoxypropylene glycol and a diisocyanate compound in the presence of a urethane reaction catalyst.

<B-1-1. Water phase component>
The aqueous phase component can be any aqueous fluid that is substantially immiscible with the continuous oil phase component. From the viewpoint of ease of handling and low cost, water such as ion-exchanged water is preferable.

  Any appropriate additive may be contained in the aqueous phase component as long as the effects of the present invention are not impaired. Examples of such additives include polymerization initiators and water-soluble salts. The water-soluble salt can be an effective additive for further stabilizing the W / O emulsion. Examples of such water-soluble salts include sodium carbonate, calcium carbonate, potassium carbonate, sodium phosphate, calcium phosphate, potassium phosphate, sodium chloride, potassium chloride and the like. Only one kind of such an additive may be contained, or two or more kinds thereof may be contained. The additive that can be contained in the aqueous phase component may be only one kind or two or more kinds.

<B-1-2. Continuous oil phase component>
The continuous oil phase component preferably contains a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer. The content ratio of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component can take any appropriate content ratio as long as the effects of the present invention are not impaired.

  The hydrophilic polyurethane-based polymer depends on the polyoxyethylene ratio in the polyoxyethylene polyoxypropylene glycol unit constituting the hydrophilic polyurethane-based polymer or the amount of the aqueous phase component to be blended. The hydrophilic polyurethane polymer is in the range of 10 to 30 parts by weight with respect to 70 to 90 parts by weight of the ethylenically unsaturated monomer, and more preferably hydrophilic to 75 to 90 parts by weight of the ethylenically unsaturated monomer. The polyurethane polymer is in the range of 10 to 25 parts by weight. Further, for example, the hydrophilic polyurethane polymer is preferably in the range of 1 to 30 parts by weight, more preferably 1 to 25 parts by weight of the hydrophilic polyurethane polymer with respect to 100 parts by weight of the aqueous phase component. It is a range. If the content ratio of the hydrophilic polyurethane polymer is within the above range, the effects of the present invention can be sufficiently exhibited.

(B-1-2-1. Hydrophilic polyurethane polymer)
The hydrophilic polyurethane-based polymer preferably contains a polyoxyethylene polyoxypropylene unit derived from polyoxyethylene polyoxypropylene glycol, and 5 wt% to 25 wt% in the polyoxyethylene polyoxypropylene unit is polyoxyethylene. Ethylene.

  The content ratio of polyoxyethylene in the polyoxyethylene polyoxypropylene unit is preferably 5% by weight to 25% by weight as described above, and is more preferably 10% by weight as the lower limit, and the upper limit. More preferably, it is 25% by weight, and more preferably 20% by weight. The polyoxyethylene in the polyoxyethylene polyoxypropylene unit exhibits an effect of stably dispersing the aqueous phase component in the continuous oil phase component. When the content of polyoxyethylene in the polyoxyethylene polyoxypropylene unit is less than 5% by weight, it may be difficult to stably disperse the water phase component in the continuous oil phase component. If the polyoxyethylene content in the polyoxyethylene polyoxypropylene unit exceeds 25% by weight, there is a risk of phase inversion from a W / O type emulsion to an O / W type (oil-in-water type) emulsion as it approaches the HIPE condition. There is.

  A conventional hydrophilic polyurethane polymer can be obtained by reacting a diisocyanate compound with a hydrophobic long-chain diol, polyoxyethylene glycol and derivatives thereof, and a low molecular active hydrogen compound (chain extender). Since the number of polyoxyethylene groups contained in the hydrophilic polyurethane polymer obtained in 1) is uneven, the emulsion stability of such a W / O emulsion containing such a hydrophilic polyurethane polymer may be reduced. There is. On the other hand, the hydrophilic polyurethane-based polymer contained in the continuous oil phase component of the W / O emulsion that can be used to obtain the foamed pressure-sensitive adhesive of the present invention has a characteristic structure as described above. When included in the continuous oil phase component of the O-type emulsion, excellent emulsifiability and excellent stationary storage stability can be expressed without positively adding an emulsifier or the like.

  The hydrophilic polyurethane-based polymer is preferably obtained by reacting polyoxyethylene polyoxypropylene glycol and a diisocyanate compound. In this case, the ratio between the polyoxyethylene polyoxypropylene glycol and the diisocyanate compound is NCO / OH (equivalent ratio), and the lower limit is preferably 1, more preferably 1.2, and still more preferably 1. .4, particularly preferably 1.6, and the upper limit is preferably 3, more preferably 2.5, and even more preferably 2. When NCO / OH (equivalent ratio) is less than 1, a gelled product may be easily formed when a hydrophilic polyurethane polymer is produced. When NCO / OH (equivalent ratio) exceeds 3, the amount of residual diisocyanate compound increases, and the W / O emulsion that can be used to obtain the foamed adhesive of the present invention may become unstable.

  As polyoxyethylene polyoxypropylene glycol, for example, polyether polyol (ADEKA (registered trademark) Pluronic L-31, L-61, L-71, L-101, L-121, L-42 manufactured by ADEKA Corporation) , L-62, L-72, L-122, 25R-1, 25R-2, 17R-2) and polyoxyethylene polyoxypropylene glycol (Pronon (registered trademark) 052, 102, manufactured by NOF Corporation. 202). As for polyoxyethylene polyoxypropylene glycol, only 1 type may be used and 2 or more types may be used together.

  Examples of the diisocyanate compound include aromatic, aliphatic, and alicyclic diisocyanates, dimers and trimers of these diisocyanates, polyphenylmethane polyisocyanate, and the like. Aromatic, aliphatic, and alicyclic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate. 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4 -Diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methyl Cyclohexane diisocyanate, m- tetramethylxylylene diisocyanate. Examples of the diisocyanate trimer include isocyanurate type, burette type, and allophanate type. Only 1 type may be used for a diisocyanate compound and it may use 2 or more types together.

  The diisocyanate compound may be selected as appropriate from the viewpoint of urethane reactivity with the polyol and the like, as well as the type and combination thereof. From the viewpoint of rapid urethane reactivity with polyol and suppression of reaction with water, it is preferable to use alicyclic diisocyanate.

  The weight average molecular weight of the hydrophilic polyurethane polymer is preferably 5000 as a lower limit, more preferably 7000, still more preferably 8000, particularly preferably 10,000, and preferably 50,000 as an upper limit. More preferably, it is 40000, more preferably 30000, and particularly preferably 20000.

  The hydrophilic polyurethane polymer may have an unsaturated double bond capable of radical polymerization at the terminal. By having an unsaturated double bond capable of radical polymerization at the terminal of the hydrophilic polyurethane-based polymer, the effects of the present invention can be further exhibited.

(B-1-2-2. Ethylenically unsaturated monomer)
As the ethylenically unsaturated monomer, any appropriate monomer can be adopted as long as it is a monomer having an ethylenically unsaturated double bond. Only one type of ethylenically unsaturated monomer may be used, or two or more types may be used.

  The ethylenically unsaturated monomer preferably comprises a (meth) acrylic ester. The content ratio of the (meth) acrylic acid ester in the ethylenically unsaturated monomer is preferably 80% by weight, more preferably 85% by weight as the lower limit, and preferably 100% by weight as the upper limit. More preferably, it is 98% by weight. Only one (meth) acrylic acid ester may be used, or two or more may be used.

  The (meth) acrylic acid ester is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms (a concept including a cycloalkyl group, an alkyl (cycloalkyl) group, and a (cycloalkyl) alkyl group). It is. Preferably the carbon number of the said alkyl group is 4-18. In addition, (meth) acryl means acryl and / or methacryl, and (meth) acrylate means acrylate and / or methacrylate.

  Examples of the alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl. (Meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isode Ru (meth) acrylate, n-dodecyl (meth) acrylate, isomyristyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, pentadecyl Examples include (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and isostearyl (meth) acrylate. Among these, n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable. Only 1 type may be sufficient as the alkyl (meth) acrylate which has a C1-C20 alkyl group, and 2 or more types may be sufficient as it.

  The ethylenically unsaturated monomer preferably further comprises a polar monomer copolymerizable with the (meth) acrylic acid ester. The content of the polar monomer in the ethylenically unsaturated monomer is preferably 0% by weight, more preferably 2% by weight as the lower limit, and preferably 20% by weight, more preferably as the upper limit. 15% by weight. Only one type of polar monomer may be used, or two or more types may be used.

  Examples of polar monomers include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, ω-carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, itaconic acid, maleic acid, fumaric acid Carboxyl group-containing monomers such as acid and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and (meth) acrylic acid 4-hydroxybutyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethyl Shi And hydroxyl group-containing monomers such as chlorohexyl) methyl (meth) acrylate; amide group-containing monomers such as N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide;

(B-1-2-3. Polymerization initiator)
The continuous oil phase component preferably contains a polymerization initiator.

  Examples of the polymerization initiator include radical polymerization initiators and redox polymerization initiators. Examples of the radical polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator.

  Examples of the thermal polymerization initiator include azo compounds, peroxides, peroxycarbonic acid, peroxycarboxylic acid, potassium persulfate, t-butylperoxyisobutyrate, and 2,2′-azobisisobutyronitrile. .

  Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone (for example, Ciba Japan, trade name: Darocur-2959), α-hydroxy- α, α'-dimethylacetophenone (for example, Ciba Japan, trade name: Darocur-1173), methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone (for example, Ciba Japan, trade name) Acetophenone photopolymerization initiators such as Irgacure-651) and 2-hydroxy-2-cyclohexylacetophenone (for example, Ciba Japan, trade name; Irgacure-184); Ketal photopolymerization initiator such as benzyldimethyl ketal Agents; Other halogenated ketones; Acylphosphine oxides (As an example, Ciba Japan Co., Ltd., trade name: Irgacure -819); and the like.

  The polymerization initiator may contain only 1 type and may contain 2 or more types.

  The content of the polymerization initiator is preferably 0.05% by weight, more preferably 0.1% by weight, more preferably 0.1%, and preferably 5.0% as a lower limit with respect to the entire continuous oil phase component. % By weight, more preferably 1.0% by weight. If the content of the polymerization initiator is less than 0.05% by weight based on the entire continuous oil phase component, the amount of unreacted monomer components may increase, and the amount of residual monomer in the resulting foamed adhesive may increase. is there. When the content of the polymerization initiator exceeds 5.0% by weight with respect to the entire continuous oil phase component, the mechanical properties of the obtained foamed adhesive may be lowered.

  Note that the amount of radicals generated by the photopolymerization initiator varies depending on the type and intensity of light to be irradiated, irradiation time, the amount of dissolved oxygen in the monomer and solvent mixture, and the like. And when there is much dissolved oxygen, the radical generation amount by a photoinitiator is suppressed, superposition | polymerization does not fully advance and an unreacted substance may increase. Therefore, before the light irradiation, it is preferable that an inert gas such as nitrogen is blown into the reaction system and oxygen is replaced with an inert gas or deaerated by a reduced pressure treatment.

(B-1-2-4. Crosslinking agent)
The continuous oil phase component preferably includes a cross-linking agent.

  Crosslinking agents are typically used to link polymer chains together to build a more three-dimensional molecular structure. The selection of the type and content of the cross-linking agent depends on the structural properties, mechanical properties, and fluid treatment properties desired for the resulting foamed adhesive. The selection of the specific type and content of the crosslinking agent is important in realizing a desirable combination of the structural characteristics, mechanical characteristics, and fluid treatment characteristics of the foamed adhesive.

  In producing the foamed pressure-sensitive adhesive body of the present invention, preferably, at least two kinds of crosslinking agents having different weight average molecular weights are used as the crosslinking agent.

  In producing the foamed adhesive body of the present invention, more preferably, the crosslinking agent is selected from “polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamide, and polymerization reactive oligomer”. "One or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide" are used in combination. Here, the polyfunctional (meth) acrylate is specifically a polyfunctional (meth) acrylate having at least two ethylenically unsaturated groups in one molecule, and the polyfunctional (meth) acrylamide is Specifically, it is polyfunctional (meth) acrylamide having at least two ethylenically unsaturated groups in one molecule.

  Examples of the polyfunctional (meth) acrylate include diacrylates, triacrylates, tetraacrylates, dimethacrylates, trimethacrylates, and tetramethacrylates.

  Examples of the polyfunctional (meth) acrylamide include diacrylamides, triacrylamides, tetraacrylamides, dimethacrylamides, trimethacrylamides, tetramethacrylamides and the like.

  The polyfunctional (meth) acrylate can be derived from, for example, diols, triols, tetraols, bisphenol A and the like. Specifically, for example, 1,10-decanediol, 1,8-octanediol, 1,6 hexane-diol, 1,4-butanediol, 1,3-butanediol, 1,4 butane-2-enedi It can be derived from all, ethylene glycol, diethylene glycol, trimethylolpropane, pentaerythritol, hydroquinone, catechol, resorcinol, triethylene glycol, polyethylene glycol, sorbitol, polypropylene glycol, polytetramethylene glycol, bisphenol A propylene oxide modified product, and the like.

  The polyfunctional (meth) acrylamide can be derived from, for example, corresponding diamines, triamines, tetraamines and the like.

  Examples of the polymerization reactive oligomer include urethane (meth) acrylate, epoxy (meth) acrylate, copolyester (meth) acrylate, oligomer di (meth) acrylate and the like. Preferably, it is hydrophobic urethane (meth) acrylate.

  The weight average molecular weight of the polymerization reactive oligomer is preferably 1500 or more, more preferably 2000 or more. Although the upper limit of the weight average molecular weight of a polymerization reactive oligomer is not specifically limited, For example, Preferably it is 10,000 or less.

  As the cross-linking agent, “one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers” and “a weight average molecular weight of 500 or less. When using together with “one or more selected from functional (meth) acrylate and polyfunctional (meth) acrylamide” ”,“ polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamide, and polymerization ” The amount of “one or more selected from reactive oligomers” is preferably 40% by weight as a lower limit with respect to the total amount of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component. The upper limit is preferably 100% by weight, and more preferably 80% by weight. The amount of use of “one or more selected from a polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, a polyfunctional (meth) acrylamide, and a polymerization reactive oligomer” is a hydrophilic polyurethane-based heavy in the continuous oil phase component If it is less than 40% by weight based on the total amount of the coalesced and ethylenically unsaturated monomer, the cohesive force of the resulting foamed adhesive may be reduced, and it may be difficult to achieve both toughness and flexibility. is there. The amount of use of “one or more selected from a polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, a polyfunctional (meth) acrylamide, and a polymerization reactive oligomer” is a hydrophilic polyurethane-based heavy in the continuous oil phase component When it exceeds 100 weight% with respect to the total amount of a coalescence and an ethylenically unsaturated monomer, the emulsion stability of a W / O type emulsion will fall, and there exists a possibility that a desired foaming adhesive body may not be obtained.

  As the cross-linking agent, “one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers” and “a weight average molecular weight of 500 or less. When using together with “one or more selected from functional (meth) acrylate and polyfunctional (meth) acrylamide” ”,“ selected from polyfunctional (meth) acrylate and polyfunctional (meth) acrylamide having a weight average molecular weight of 500 or less ” The amount of “one or more” used is preferably 1% by weight, more preferably 5% as a lower limit with respect to the total amount of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component. The upper limit is preferably 30% by weight, and more preferably 20% by weight. Use amount of “one or more selected from polyfunctional (meth) acrylate having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide” is a hydrophilic polyurethane polymer and ethylenic unsaturated in a continuous oil phase component When the amount is less than 1% by weight based on the total amount of monomers, the heat resistance is lowered, and the cell structure may be crushed by contraction in the step (IV) of dehydrating the water-containing polymer. Use amount of “one or more selected from polyfunctional (meth) acrylate having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide” is a hydrophilic polyurethane polymer and ethylenic unsaturated in a continuous oil phase component When it exceeds 30 weight% with respect to the total amount of a monomer, the toughness of the foaming adhesive body obtained may fall, and there exists a possibility that brittleness may be shown.

  The crosslinking agent may contain only 1 type and may contain 2 or more types.

(B-1-2-5. Other components in the continuous oil phase component)
The continuous oil phase component may contain any appropriate other component as long as the effects of the present invention are not impaired. Typically, such other components preferably include a catalyst, an antioxidant, an organic solvent, and the like. Such other components may be only one type or two or more types.

  Examples of the catalyst include a urethane reaction catalyst. Any appropriate catalyst can be adopted as the urethane reaction catalyst. Specific examples include dibutyltin dilaurate.

  Arbitrary appropriate content rates can be employ | adopted for the content rate of a catalyst according to the target catalytic reaction.

  The catalyst may contain only 1 type and may contain 2 or more types.

  Examples of the antioxidant include a phenol-based antioxidant, a thioether-based antioxidant, and a phosphorus-based antioxidant.

  Arbitrary appropriate content rates can be employ | adopted for the content rate of antioxidant in the range which does not impair the effect of this invention.

  Antioxidant may contain only 1 type and may contain 2 or more types.

  Any appropriate organic solvent can be adopted as the organic solvent as long as the effects of the present invention are not impaired.

  Arbitrary appropriate content rates can be employ | adopted for the content rate of an organic solvent in the range which does not impair the effect of this invention.

  The organic solvent may contain only 1 type and may contain 2 or more types.

<< B-2. Step of shaping W / O type emulsion (II) >>
In the step (II), any appropriate shaping method can be adopted as a method for shaping the W / O type emulsion. For example, there is a method in which a W / O emulsion is continuously supplied onto a traveling belt and shaped into a smooth sheet on the belt. Moreover, the method of apply | coating to one surface of a thermoplastic resin film, and shaping is mentioned.

  In the step (II), as a method of shaping the W / O type emulsion, when adopting a method of coating and shaping on one surface of a thermoplastic resin film, as a method of coating, for example, a roll coater, Examples include a method using a die coater, a knife coater, or the like.

<< B-3. Step of polymerizing shaped W / O emulsion (III) >>
In the step (III), any appropriate polymerization method can be adopted as a method for polymerizing the shaped W / O emulsion. For example, the belt surface of a belt conveyor is heated by a heating device, and a W / O type emulsion is continuously supplied onto a traveling belt and shaped into a smooth sheet on the belt by heating. A W / O emulsion is continuously supplied onto the running belt, with a method of polymerization and a structure in which the belt surface of the belt conveyor is heated by irradiation of active energy rays, and a smooth sheet is formed on the belt. The method of superposing | polymerizing by irradiation of an active energy ray is mentioned, shaping.

  In the case of polymerization by heating, the polymerization temperature (heating temperature) is preferably 23 ° C., more preferably 50 ° C., still more preferably 70 ° C., particularly preferably 80 ° C. as the lower limit. The upper limit is preferably 90 ° C, and is preferably 150 ° C, more preferably 130 ° C, and even more preferably 110 ° C. When the polymerization temperature is less than 23 ° C., the polymerization takes a long time, and industrial productivity may be reduced. When the polymerization temperature exceeds 150 ° C., the pore diameter of the foamed adhesive body to be obtained may be nonuniform, and the strength of the foamed adhesive body may be reduced. The polymerization temperature need not be constant. For example, the polymerization temperature may be varied in two stages or multiple stages during the polymerization.

  In the case of polymerization by irradiation with active energy rays, examples of the active energy rays include ultraviolet rays, visible rays, and electron beams. The active energy ray is preferably ultraviolet light or visible light, and more preferably visible to ultraviolet light having a wavelength of 200 nm to 800 nm. Since the W / O type emulsion has a strong tendency to scatter light, it is possible to penetrate the W / O type emulsion by using visible to ultraviolet light having a wavelength of 200 nm to 800 nm. Moreover, the photoinitiator which can be activated with a wavelength of 200 nm-800 nm is easy to obtain, and a light source is easy to obtain.

  The wavelength of the active energy ray is preferably 200 nm, more preferably 300 nm as the lower limit value, and preferably 800 nm, more preferably 450 nm as the upper limit value.

  As a typical apparatus used for irradiation of active energy rays, for example, an ultraviolet lamp capable of performing ultraviolet irradiation includes an apparatus having a spectral distribution in a wavelength region of 300 to 400 nm. , Black light (trade name manufactured by Toshiba Lighting & Technology Co., Ltd.), metal halide lamp and the like.

  The illuminance at the time of irradiation with active energy rays can be set to any appropriate illuminance by adjusting the distance from the irradiation device to the irradiation object and the voltage. For example, by the method disclosed in Japanese Patent Application Laid-Open No. 2003-13015, the ultraviolet irradiation in each step is performed in a plurality of stages, thereby making it possible to precisely adjust the adhesive performance.

  In order to prevent the adverse effect of oxygen having an inhibitory action on the ultraviolet rays, for example, a W / O emulsion is applied to one surface of a substrate such as a thermoplastic resin film and then shaped under an inert gas atmosphere. UV rays such as polyethylene terephthalate coated with a release agent such as silicone after passing through a W / O emulsion on one surface of a substrate such as a thermoplastic resin film and shaping, but blocking oxygen It is preferable to carry out by covering the film.

  As the thermoplastic resin film, any appropriate thermoplastic resin film can be adopted as long as it can be formed by coating a W / O emulsion on one surface. Examples of the thermoplastic resin film include plastic films and sheets such as polyester, olefin resin, and polyvinyl chloride.

  The inert gas atmosphere refers to an atmosphere in which oxygen in the light irradiation zone is replaced with an inert gas. Therefore, in the inert gas atmosphere, it is necessary that oxygen is not present as much as possible, and the oxygen concentration is preferably 5000 ppm or less.

<< B-4. Step of dehydrating the obtained water-containing polymer (IV) >>
In step (IV), the obtained water-containing polymer is dehydrated. In the water-containing polymer obtained in step (III), the aqueous phase component is present in a dispersed state. By removing the aqueous phase component by dehydration and drying, a foam contained in the foamed adhesive body of the present invention is obtained. The obtained foam can be used as the foamed adhesive body of the present invention as it is. Moreover, it can become the foaming adhesive body of this invention by combining with a base material so that it may mention later.

  Arbitrary appropriate drying methods can be employ | adopted as a dehydration method in process (IV). Examples of such a drying method include vacuum drying, freeze drying, press drying, microwave drying, drying in a heat oven, drying with infrared rays, or a combination of these techniques.

<< B-5. When the foamed adhesive of the present invention contains a base material >>
When the foamed pressure-sensitive adhesive of the present invention contains a substrate, as one of the preferred embodiments of the method for producing a foamed pressure-sensitive adhesive of the present invention, a W / O emulsion is applied to one surface of the substrate, and an inert gas is used. In the atmosphere or with a UV transparent film coated with a release agent such as silicone, the W / O emulsion is polymerized by heating or irradiating active energy rays in a state where oxygen is blocked. A form in which a foamed pressure-sensitive adhesive body having a substrate / foamed layer laminated structure is obtained by dehydrating the resulting hydropolymer as a coalescence is exemplified.

  As another preferred embodiment of the method for producing a foamed pressure-sensitive adhesive body of the present invention, two sheets of W / O type emulsions coated on one surface of a UV transparent film coated with a release agent such as silicone were prepared. A base material is laminated on the application surface of one of the two W / O emulsion coating sheets, and another W / O emulsion coating sheet is formed on the other surface of the laminated base material. In a state in which the coated surfaces are laminated so as to match with each other, heating or irradiation with active energy rays is performed to polymerize the W / O emulsion to form a water-containing polymer, and the resulting water-containing polymer is dehydrated to obtain a foam layer. The form made into the foaming adhesive body which has the laminated structure of / substrate / foaming layer is mentioned.

  Examples of the method of coating the W / O type emulsion on one side of the base material or one surface of the ultraviolet ray transmissive film coated with a release agent such as silicone include a roll coater, a die coater, and a knife coater.

  Hereinafter, although the present invention is explained based on an example, the present invention is not limited to these. The normal temperature means 23 ° C.

(Molecular weight measurement)
The weight average molecular weight was determined by GPC (gel permeation chromatography).
Equipment: “HLC-8020” manufactured by Tosoh Corporation
Column: “TSKgel GMH _HR- H (20)” manufactured by Tosoh Corporation
Solvent: Tetrahydrofuran Standard: Polystyrene

(Measurement of average pore diameter)
A sample for measurement was prepared by cutting the prepared composite sheet with a microtome cutter in the thickness direction. The cut surface of the sample for measurement was photographed with a scanning electron microscope (Hitachi, S-3400N) at 800 to 5000 times. Using the photographed image, measure the pore diameter of an arbitrary range of spherical bubbles, the diameter of a through-hole penetrating between the spherical bubbles of an arbitrary range, and the pore diameter of the surface opening of an arbitrary range. The average hole diameter, the average hole diameter of the through holes, and the average hole diameter of the surface openings were calculated.

(Measurement of normal shear adhesive strength)
The obtained foamed adhesive was cut into 20 mm × 20 mm, and BA plates (SUS304) were attached to both sides of the foamed adhesive. A 2 kg roller was reciprocated once to press the sample placed horizontally. After crimping, the sample was left at room temperature overnight, fixed to Tensilon so that the sample was vertical at room temperature, pulled at a pulling rate of 50 mm / min, and the shear adhesive force was measured. Samples were measured at n = 2, and the average value was defined as normal shear adhesive strength.

(Measurement of 180 ° peel test force)
The obtained foamed adhesive body was cut into 25 mm × 100 mm, one separator was peeled off and attached to a BA board (SUS304), and a 2 kg roller was reciprocated once to perform pressure bonding. After crimping, the sample was allowed to stand at room temperature for 30 minutes, peeled in the direction of 180 ° at a tensile speed of 50 mm / min using Tensilon, and the peel adhesive force was measured. Samples were measured at n = 2, and the average value was defined as a 180 ° peel test force.

(Measurement of 60 ° C holding power)
The obtained foamed adhesive was cut into 10 mm × 100 mm, and one separator was peeled off and attached to a baking plate so as to have an attachment area of 10 mm × 20 mm. After pressure bonding, a baking plate was fixed so that the sample was vertical in an atmosphere of 60 ° C., and a load of 500 g was applied to one foamed adhesive, and left for 2 hours. After leaving, the amount of deviation of the sample application position after 2 hours was measured.

(Measurement of 50% compression load)
After laminating 10 sheets of the obtained foamed adhesive, it was cut into 20 mm × 20 mm to obtain a measurement sample. Tensilon was used for the measurement. The sample for measurement was compressed in the thickness direction to 50% of the initial thickness at a speed of 10 mm / min, and the maximum value when the thickness was compressed by 50% was measured. Samples were measured at n = 2, and the average value was 50% compression load.

(Dimensional change rate when stored at 125 ° C for 22 hours)
The heating dimensional change of the obtained foamed adhesive was measured based on the dimensional stability evaluation at high temperature of JIS-K-6767. That is, the produced foam was cut out to a size of 100 mm × 100 mm to form a test piece, stored in an oven at 125 ° C. for 22 hours, and then in accordance with the dimensional stability evaluation at high temperature of JIS-K-6767, The dimensional change rate before and after the heat storage treatment was determined.

(Measurement of density of foamed adhesive)
Five sheets of the obtained foamed adhesive were cut into a size of 100 mm × 100 mm to obtain test pieces, and the apparent density was determined by dividing the weight by the volume. The average value of the apparent density obtained was taken as the density of the foamed adhesive.

(Measurement of bubble rate)
Only the oil phase component at the time of producing the emulsion was polymerized, and the obtained polymer sheet was cut into five pieces of 100 mm × 100 mm to obtain test pieces, and the apparent density was obtained by dividing the weight by the volume. The average value of the apparent density obtained was taken as the density of the resin component constituting the foamed adhesive. The cell ratio of the foamed adhesive was calculated according to the following formula using the relative density obtained by dividing the density of the foamed adhesive by the density of the resin component.
Bubble ratio = (1−relative density) × 100

[Production Example 1]: Preparation of mixed syrup 1 In a reaction vessel equipped with a condenser, a thermometer, and a stirrer, 2-ethylhexyl acrylate (manufactured by Toagosei Co., Ltd., hereinafter "2EHA") as an ethylenically unsaturated monomer A monomer solution consisting of 173.2 parts by weight, and 100 parts by weight of Adeka (registered trademark) Pluronic L-62 (molecular weight 2500, manufactured by ADEKA Corporation, polyether polyol) as polyoxyethylene polyoxypropylene glycol, As a urethane reaction catalyst, 0.014 part by weight of dibutyltin dilaurate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “DBTL”) is added and stirred, and hydrogenated xylylene diisocyanate (manufactured by Takeda Pharmaceutical Co., Ltd., Takenate). 600, hereinafter abbreviated as “HXDI”) 12.4 parts by weight were added dropwise and reacted at 65 ° C. for 4 hours. Let In addition, the usage-amount of the polyisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.6. Thereafter, 5.6 parts by weight of 2-hydroxyethyl acrylate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “HEA”) is dropped and reacted at 65 ° C. for 2 hours, and a hydrophilic polyurethane system having acryloyl groups at both ends. A polymer / ethylenically unsaturated monomer mixed syrup was obtained. The weight average molecular weight of the obtained hydrophilic polyurethane polymer was 15,000. 48 parts by weight of 2EHA with respect to 100 parts by weight of the obtained hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup, acrylic acid (manufactured by Toa Gosei Co., Ltd., hereinafter abbreviated as “AA”) 12 parts by weight A hydrophilic polyurethane-based polymer / ethylenically unsaturated monomer mixed syrup 1 was added.

[Example 1]
To 100 parts by weight of the hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 obtained in Production Example 1, 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester A” -HD-N ") (molecular weight 226) 10 parts by weight, a reactive oligomer of polyurethane synthesized from polytetramethylene glycol (hereinafter abbreviated as" PTMG ") and isophorone diisocyanate (hereinafter abbreviated as" IPDI ") Both ends treated with HEA, urethane acrylate having ethylenically unsaturated groups at both ends (hereinafter abbreviated as “UA”) (molecular weight 3720), 56 parts by weight, diphenyl (2,4,6-trimethylbenzoyl) phos Fin oxide (BASF, trade name "Lucirin TPO") 0.5 parts by weight, hindered pheno Le-based antioxidant (manufactured by Ciba Japan, trade name "Irganox 1010") 1.0 part by weight were uniformly mixed, continuous oil phase component (hereinafter, referred to as "oil phase") was. On the other hand, 300 parts by weight of ion-exchanged water as an aqueous phase component (hereinafter referred to as “aqueous phase”) with respect to 100 parts by weight of the oil phase is continuously introduced into a stirring mixer that is an emulsifier charged with the oil phase at room temperature. Were added dropwise to prepare a stable W / O emulsion. The weight ratio of the water phase to the oil phase was 75/25.
The foamed layer after light irradiation was prepared on a polyethylene terephthalate film (hereinafter referred to as “PET film”) having a thickness of 38 μm, and a W / O emulsion that had been stored at room temperature for 30 minutes by standing. The film was applied so as to have a thickness of 150 μm and continuously formed into a sheet shape. Furthermore, a 70 μm thick polyester fiber laminated fabric (trade name “Milife (registered trademark) TY1010E” manufactured by Nisshi Plast Co., Ltd.) in which stretched polyester long fibers were laminated in a vertical arrangement was laminated. Further, separately from the preparation, the W / O type emulsion, which was stored at room temperature for 30 minutes, was placed on a PET film having a thickness of 38 μm, and the foamed layer after light irradiation had a thickness of 150 μm. A coated material was prepared, and the coated surface was covered with the polyester fiber laminated fabric. This sheet was irradiated with ultraviolet light having a light illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a peak sensitivity maximum wave of 350 nm) using a black light (15 W / cm) to obtain a highly hydrous crosslinked polymer having a thickness of 310 μm. . Next, the top film was peeled off, and the high water content crosslinked polymer was heated at 130 ° C. for 10 minutes to obtain a foamed adhesive body (1) having a thickness of about 0.3 mm.
The results are shown in Table 1.
Moreover, the photograph figure of the surface / cross-section SEM photograph which image | photographed the produced foaming adhesive body from diagonally was shown in FIG.

[Example 2]
In Example 1, a stable W / O emulsion was prepared in the same manner as in Example 1 except that 186 parts by weight of ion-exchanged water was continuously added dropwise at room temperature as an aqueous phase. The weight ratio of the water phase to the oil phase was 65/35.
Next, in the same manner as in Example 1, a foamed adhesive body (2) having a thickness of about 0.3 mm was obtained.
The results are shown in Table 1.

Example 3
In Example 1, a stable W / O emulsion was prepared in the same manner as in Example 1 except that 567 parts by weight of ion-exchanged water was continuously added dropwise at room temperature as an aqueous phase. The weight ratio of the water phase to the oil phase was 85/15.
Next, as in Example 1, a foamed adhesive body (3) having a thickness of about 0.4 mm was obtained.
The results are shown in Table 1.

  The foamed adhesive body of the present invention is suitable for various adhesive applications.

100 Foam pressure-sensitive adhesive body 10 Foam body 10a Foam body 10b Foam body 20 Base material 30 Release film

Claims (7)

A foamed pressure-sensitive adhesive comprising a foam having an open-cell structure having through-holes between adjacent spherical bubbles,
The foamed pressure-sensitive adhesive is produced by shaping and polymerizing a W / O emulsion containing a continuous oil phase component and an aqueous phase component immiscible with the continuous oil phase component. Containing a water-soluble polyurethane polymer and an ethylenically unsaturated monomer,
The average pore size of the spherical bubbles is less than 20 μm,
The average pore diameter of the through holes is 5 μm or less,
The surface of the foam has a surface opening having an average pore diameter of 20 μm or less,
The normal shear adhesive strength is 1 N / cm ² or more,
Foam adhesive.   The foaming adhesive body of Claim 1 whose 180 degree peel test force is 1 N / 25mm or less.   The foaming adhesive body of Claim 1 or 2 whose 60 degreeC retention strength is 0.5 mm or less. The foaming adhesive body in any one of Claim 1 to 3 whose 50% compression load is 150 N / cm < ² > or less.   The foamed pressure-sensitive adhesive according to any one of claims 1 to 4, wherein a dimensional change rate when stored at 125 ° C for 22 hours is less than ± 5%. Wherein the foam has a density in the ^{0.15g / cm 3 ~0.6g / cm 3} , the foamed adhesive body according to any one of claims 1 to 5. The foamed pressure-sensitive adhesive according to any one of claims 1 to 6, wherein a foam ratio of the foam is 30% or more.