JP2998874B2 - Multi-layer adhesive structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layered pressure-sensitive adhesive structure having three or more layers, such as a pressure-sensitive adhesive tape or a pressure-sensitive adhesive sheet, comprising only a pressure-sensitive adhesive layer. At least one pressure-sensitive adhesive layer (A) having at least one pressure-sensitive adhesive layer (A) which is relatively toughened with respect to the pressure-sensitive adhesive layer (B) as the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure. ,
The multilayer pressure-sensitive adhesive structure relates to a multilayer pressure-sensitive adhesive structure having substantially no air bubbles and a tensile elongation in a specific range.

[0002]

2. Description of the Related Art Conventionally, it has been widely used to fix various parts and the like with a double-sided adhesive tape or the like. However, insufficient adhesive strength of the pressure-sensitive adhesive layer, poor creep properties, difficulty in sticking to curved surfaces, pressure during formation and storage of the pressure-sensitive adhesive layer,
There are many problems such as changes in physical properties due to external factors such as heat, humidity, and light. On the other hand, improvement of the adhesive itself,
A method of sandwiching a film or sheet such as a nonwoven fabric or a foam sheet between the adhesive layers, a method of including air bubbles in the adhesive layer, and a method of including a hollow body such as a glass balloon have been proposed.

However, it is not easy to sufficiently satisfy the conflicting properties of the adhesive force and the creep property only by the method of improving the pressure-sensitive adhesive itself, and it is actually difficult to sufficiently satisfy the industrial needs. The situation.

The method of sandwiching a hard sheet made of nonwoven fabric or plastic between the adhesive layers lacks flexibility and is not always satisfactory in terms of physical properties such as adhesive strength and curved surface applicability. Also, when sandwiching a foamed sheet, if it is a hard foamed sheet, it has the same disadvantages as when sandwiching a nonwoven fabric, and if it is a soft sheet, if the pressure at the time of use is too high, it will dent and restore that part However, there are problems such as insufficient adhesion and the occurrence of peeling at the interface between the foamed sheet and the pressure-sensitive adhesive.

Further, in the method of including bubbles in the pressure-sensitive adhesive layer, as in the case of a foamed sheet sandwich, if the pressure during use is too high, dents may occur, and uniform dispersion of bubbles during production may occur. A complicated and difficult process is required, and the physical properties of the pressure-sensitive adhesive sheet such as water absorption resistance and moisture absorption resistance are often reduced. In particular, when containing a hollow body such as a glass balloon in the adhesive layer,
Problems such as difficulty in uniformly dispersing the hollow body during production and uneven crushing due to stirring and mixing are inevitable, and it is not easy to obtain a pressure-sensitive adhesive sheet of stable quality.

As described above, the conventional various proposals for the pressure-sensitive adhesive sheet have their respective drawbacks, and an excellent pressure-sensitive adhesive sheet which has simultaneously solved the above-mentioned problems has not yet been completed. The present invention intends to solve these problems at the same time.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a high degree of adhesive properties, creep properties, curved surface applicability, and the like, and furthermore, the pressure, heat and humidity during the formation and storage of the adhesive layer. Another object of the present invention is to provide a pressure-sensitive adhesive structure which has stable pressure-sensitive adhesive properties even with external factors such as light and has good productivity.

In the present invention, in a multilayer pressure-sensitive adhesive structure of three or more layers consisting of only a pressure-sensitive adhesive layer, at least 2
At least one pressure-sensitive adhesive layer (A) has at least one pressure-sensitive adhesive layer, and at least one pressure-sensitive adhesive layer (A) is relatively toughened with respect to the pressure-sensitive adhesive layer (B), which is the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure. The present invention provides a multilayer pressure-sensitive adhesive structure characterized in that the multilayer pressure-sensitive adhesive structure is substantially free of air bubbles and has a tensile elongation of 100 to 5000%. Is the solution.

Hereinafter, the present invention will be described in detail. As the pressure-sensitive adhesive resin used in the pressure-sensitive adhesive layer in the present invention, it is preferable to use an acrylic resin from the viewpoint of excellent weather resistance and the like.

As the acrylic resin, for example, 2-
A (meth) acrylate (co) polymer mainly composed of an acrylate such as ethylhexyl acrylate or n-octyl acrylate can be used.

[0011]

As the acrylic resin suitably used in the present invention, for example, ethyl acrylate, n-propyl acrylate, n-butyl acrylate,
n-hexyl acrylate, n-octyl acrylate, i-
(Co) polymers of acrylic acid esters (hereinafter sometimes referred to as main monomers) such as octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, and i-nonyl acrylate;

Further, these main monomers are mainly used, and if necessary, for example, methyl acrylate, t-
Other acrylates such as butyl acrylate; for example, methacrylates such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate; for example, vinyl formate, vinyl acetate, vinyl propionate, "vinyl versatate" (Trade name) and the like; saturated fatty acid vinyl esters such as (trade name); for example, aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyl toluene; for example, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile;
Vinyl monomers such as vinyl chloride and vinylidene chloride; olefin monomers such as ethylene, propylene, n-butene, i-butene, butadiene, isoprene and chloroprene; Acrylic ester-based copolymer obtained by copolymerizing

Further, if necessary, a monomer having at least one functional group in addition to one ethylenically unsaturated group in the molecule together with the main monomer and comonomer (hereinafter referred to as a functional group). Reactive acrylate-based copolymer obtained by copolymerizing a reactive monomer).

Examples of such functional monomers include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, citraconic acid, itaconic acid, maleic acid and fumaric acid; for example, acrylamide, methacrylamide, Amide or substituted amide group-containing monomers such as N-methylol acrylamide and N-methylol methacrylamide; epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, and glycidyl methallyl ether;

For example, hydroxyl-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; amino groups such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate Or a monomer having a substituted amino group; for example, an active silicon-containing monomer such as vinyltrichlorosilane, vinyltriethoxysilane, and 3- (meth) acryloxypropylmethoxysilane; for example, divinylbenzene, diallylphthalate, triaryl Lucyanurate, triallyl isocyanurate, ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate,
Neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol trimethylolpropane tri (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol (meth) Monomers having two or more ethylenically unsaturated groups, such as acrylate, tripropylene glycol (meth) acrylate, and allyl methacrylate; and the like.

The tacky resin which can be used in the present invention includes, for example, solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, radiation polymerization using ultraviolet rays and electron beams, ionic polymerization, addition polymerization, polycondensation and the like. It can be manufactured by a conventionally known method. Particularly in the case of an acrylic resin, one or more of the main monomers, or the main monomer and the comonomer, and furthermore, these and the functional monomer, for example, solution polymerization, It can be produced by a method such as emulsion polymerization, bulk polymerization, suspension polymerization, or radiation polymerization using an ultraviolet ray, an electron beam, or the like.

[0018]

The adhesive resin used in the present invention is generally preferably one having a high molecular weight, but is not necessarily limited thereto, and may be a mixture of one having a high molecular weight and one having a low molecular weight. In addition, depending on the use, those having a low molecular weight can also be used. In addition, the adhesive resin of the present invention is generally preferable because it has crosslinking reactivity because the degree of crosslinking can be adjusted according to the purpose.

The hardness of the adhesive resin used in the present invention is as follows:
It can be varied in any way by various choices of the monomers, especially when used in the low temperature range, Tg
When used in a high temperature range, the combination is appropriately selected depending on the combination of monomers having a high Tg. Crosslinking reactions also serve to increase the application temperature.

In the present invention, in a multilayer pressure-sensitive adhesive structure of three or more layers composed of only a pressure-sensitive adhesive layer, at least 2
At least one pressure-sensitive adhesive layer (A) has at least one pressure-sensitive adhesive layer, and at least one pressure-sensitive adhesive layer (A) is relatively toughened with respect to the pressure-sensitive adhesive layer (B), which is the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure. Need to be done. In the present invention, in addition to the pressure-sensitive adhesive layer (A) and the pressure-sensitive adhesive layer (B), another pressure-sensitive adhesive layer (C) can be provided as an intermediate layer.

A method for toughening the pressure-sensitive adhesive layer (A) with respect to the pressure-sensitive adhesive layer (B), or the pressure-sensitive adhesive layer (B) and the pressure-sensitive adhesive layer (C) is as follows.

(1) a method of adding a filler to the pressure-sensitive adhesive layer (A),

(2) A method in which the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer (A) is a resin having a higher degree of crosslinking than the pressure-sensitive adhesives of the other layers,

(3) A method in which the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer (A) is a resin having a higher molecular weight than the pressure-sensitive adhesive of the other layers,

(4) a method in which the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer (A) has a higher Tg than the pressure-sensitive adhesive in the other layers; and

(5) A method combining two or more of the above (1), (2), (3) and (4),

Any method can be used.
However, these toughening methods require that the tensile elongation of the multilayer pressure-sensitive adhesive structure be set in the range of 100 to 5000%.

The toughening method (1) can be achieved by adding various fillers. The amount of the filler to be added is preferably 1 to 60% by volume, more preferably 1 to 50% by volume, still more preferably 5 to 40% by volume, based on 100% by volume of the resin of the pressure-sensitive adhesive layer (A). Is good.

The size of the filler particles is determined by the size of the pressure-sensitive adhesive layer.
It is sufficient that the size does not exceed the thickness of (A), preferably
It is 0.1 to 200 µ, more preferably 1 to 100, particularly preferably 1 to 60 µ. By adjusting the size of the particles within the above range, generally, among the objects of the present invention, excellent characteristics such as appropriate tensile elongation of the obtained multilayer pressure-sensitive adhesive structure and smoothness of the pressure-sensitive adhesive layer are exhibited. It is preferred.

As the filler that can be used in the present invention, any of an organic filler and an inorganic filler can be used as long as the filler can be stably dispersed in the pressure-sensitive adhesive layer (A).

Examples of the organic filler include powders of various (co) polymers, for example, (meth) acrylates such as methyl methacrylate polymer, ethyl methacrylate polymer and methyl methacrylate-divinylbenzene copolymer. -Based (co) polymer; for example, styrene-based (co) polymers such as styrene polymer and styrene-divinylbenzene copolymer; for example, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene- Olefinic (co) polymers such as propylene copolymers;

For example, styrene-butadiene copolymer,
Styrene-isoprene copolymer, acrylonitrile-butadiene copolymer, methyl methacrylate-butadiene copolymer, cross-linked isoprene rubber, cross-linked chloroprene rubber,
Rubber resins such as cross-linked butyl rubber; vinyl chloride (co) polymer; vinylidene chloride (co) polymer; fluororesin; saturated polyester resin; polyamide resin;

Powders of various thermoplastic resins or thermosetting resins such as unsaturated polyester resins; polycarbonate resins; amino resins; silicone resins; epoxy resins; urethane resins; powder,
Cellulose-based polymer powders such as powdered rayon and the like can be mentioned.

Examples of the inorganic filler include, for example,
Metal powders such as aluminum, copper, brass, iron, steel, stainless steel, zinc, lead or whiskers of these metals; for example, metal oxides such as aluminum oxide, titanium oxide, silicon oxide, magnesium oxide, clay, mica, talc Or a mixture thereof; for example, a metal salt such as calcium carbonate, magnesium carbonate, barium sulfate; a metal hydroxide such as aluminum hydroxide, magnesium hydroxide;
For example, metal carbides or nitrides such as silicon carbide, titanium carbide, silicon nitride, titanium nitride, and aluminum nitride; glass flakes, glass fibers; and carbons such as graphite, glassy carbon, activated carbon, carbon fibers, and carbon whiskers; And the like.

The shape of these fillers is not particularly limited, and may be spherical, massive, flat, fibrous, needle-like,
Any other shapes can be used.

In the present invention, only one of the fillers appropriately selected may be used, but a mixture of two or more fillers may be used. The filler can be used at any time depending on the application regardless of the adhesiveness of the adhesive resin forming the adhesive layer (A) and the adhesiveness thereof. More preferred.

However, in the present invention, when used as a thin balloon, when mixed with an adhesive layer, it is destroyed by external pressure or the like, or is unevenly distributed in the adhesive layer due to a difference in specific gravity with the adhesive resin. On the other hand, it is not appropriate to use a filler as a main component, which makes it difficult to maintain stable physical properties, which is one of the main objects of the present invention. However, any material that is hardly crushed by an external pressure and hardly affects the adhesive properties, such as a glass balloon having a large outer shell, can be used. Even a thin glass balloon may be added in a small amount that does not affect the adhesive properties even if crushing occurs.

The method for dispersing the filler in the pressure-sensitive adhesive layer (A) is as follows.
Depending on the form of the pressure-sensitive adhesive resin before the formation of the pressure-sensitive adhesive layer (A), a conventionally used method such as an ink mill, a pot mill, a disper, and a melt-kneading can be appropriately used. When the pressure-sensitive adhesive layer (A) is obtained by performing polymerization using radiation such as an electron beam and ultraviolet light, a filler is mixed and dispersed in a monomer to be used, and then polymerized by irradiation to perform a predetermined process. You can get things.

Since the mixing and dispersion of the filler can be carried out extremely easily as described above, there is no problem when air bubbles or hollow bodies are put in the pressure-sensitive adhesive layer as in the prior art. In these conventional techniques, for example, when using a foaming agent to put bubbles in the pressure-sensitive adhesive layer, in addition to uniform dispersion of the foaming agent at the time of production, in order to install foaming process equipment, to make the foaming ratio uniform It is necessary to solve a number of problems such as complicated foaming materials and complicated control of the foaming temperature. Also, when introducing bubbles mechanically, it is not easy to adjust the mechanical conditions for producing uniform bubbles during production, and the generated bubbles tend to be open cells, resulting in the strength and physical properties of the pressure-sensitive adhesive layer. Tend to be insufficient.

Further, when a hollow body such as a glass balloon is used, the hollow body is liable to be partially broken by mechanical force due to dispersion and mixing at the time of production. The prior art has many problems to be overcome, such as difficulty in obtaining a pressure-sensitive adhesive sheet having stable physical properties because it is not constant. On the other hand, the mixing of the filler with the adhesive resin in the present invention does not require any complicated operation, and the product quality can be stabilized very easily.

In the toughening method (2), the pressure-sensitive adhesive layer
The adhesive resin used in (A) can be achieved by using a resin having a higher degree of crosslinking than the adhesive resin of the adhesive layer (B), which is the outermost layer on at least one side of the multilayer adhesive structure. Although the creep performance can be further improved by this method, if the degree of crosslinking is excessively increased, the tensile elongation of the multilayer pressure-sensitive adhesive structure may decrease to less than 100%. There is a need.

As a method of increasing the degree of crosslinking, a method of copolymerizing a monomer having two or more ethylenically unsaturated groups in one molecule such as diallyl phthalate as described above during the production of a resin; Unsaturated carboxylic acids such as acrylic acid,
Hydroxyl-containing monomers such as 2-hydroxyethyl methacrylate, epoxy-containing monomers such as glycidyl methacrylate, substituted amide-containing monomers such as N-methylolacrylamide, and active silicon-containing monomers such as vinyltriethoxysilane After introducing a functional group by copolymerizing a functional monomer such as an isocyanate compound, a silane compound,
A method of adding and reacting a cross-linking agent such as an organometallic compound, an epoxy compound, or an aziridine compound; and the like, and if necessary, other methods.

Among the above crosslinking agents, isocyanate compounds include, for example, m- or p-phenylenediisocyanate, 2,4- or 2,6-tolylene diisocyanate, m- or p-xylylene diisocyanate, 4 Aromatic diisocyanate compounds such as 4,4'-diphenylmethane diisocyanate; for example, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated products of the above aromatic diisocyanate compounds, aliphatic or alicyclic diisocyanate compounds such as dimer acid diisocyanate; Adducts of these isocyanates with, for example, divalent or trivalent polyols such as ethylene glycol and trimethylolpropane.

Blocked isocyanate compounds can also be used. Examples thereof include those obtained by adding a volatile low-molecular-weight active hydrogen compound to the polyisocyanate compound, such as trimethylolpropane tolylene diisocyanate methyl ethyl ketoxime adduct. ,

Examples of such volatile low-molecular-weight active hydrogen compounds include methyl alcohol, ethyl alcohol, n-butyl alcohol, cyclohexyl alcohol,
Aliphatic, alicyclic or aromatic alcohols such as benzyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and phenol; hydroxytertiary amines such as dimethylaminoethanol and diethylaminoethanol; for example, acetoxime, methylethylketoxime and the like; Ketoximes;
Examples thereof include active methylene compounds such as acetylacetone, acetoacetate, and malonate; lactams such as ε-caprolactam;

Examples of the silane compounds include 3-glycidoxypropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldimethoxysilane, and 3-mercaptopropyl Trimethoxysilane, 3-chloropropyltrimethoxysilane and the like; examples of the organometallic compound include isopropyltriisostearoyl titanate, isopropyltrioctanoyl titanate, and isopropyltris.
(Dioctyl pyrophosphate) titanate, titanium diisostearate oxyacetate, aluminum isopropionate, aluminum-s-butyrate, mono-s-butoxyaluminum diisopropionate, ethyl acetoacetate aluminum diisopropionate, aluminum tris (ethyl Acetoacetate) and the like;

As the epoxy compound, for example, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like;

As the aziridine compound, a reaction product of the isocyanate compound with ethyleneimine, for example, a reaction product of 4,4'-diphenylmethane diisocyanate with ethyleneimine can be used.

Further, various catalysts can be used in combination as a crosslinking accelerator, if necessary.

In the toughening method (3), the pressure-sensitive adhesive resin used for the pressure-sensitive adhesive layer (A) is changed to the pressure-sensitive adhesive property of the pressure-sensitive adhesive layer (B), which is the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure. This can be achieved by using a resin having a higher molecular weight than the resin.

In order to increase the molecular weight, it is necessary to increase the monomer concentration, lower the polymerization initiator concentration, or lower the radical polymerization temperature in the production of the adhesive resin used for the adhesive layer (A). It can be achieved relatively easily by appropriately selecting the reaction conditions based on known theory and knowledge such as employing ionic polymerization. Further, it can also be obtained by separating only a high molecular weight portion from a resin obtained by ordinary polymerization by a known method such as a solution fractionation method. Further, this object can be achieved by blending a resin having a high molecular weight only into the adhesive resin used for the adhesive layer (A).

In the toughening method (4), the pressure-sensitive adhesive resin used for the pressure-sensitive adhesive layer (A) is changed to the pressure-sensitive adhesive property of the pressure-sensitive adhesive layer (B), which is the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure. This can be achieved by using a resin having a higher Tg than a resin.

As a method for increasing the Tg, the pressure-sensitive adhesive layer (A)
In the production of the pressure-sensitive adhesive resin to be used, according to known theory and knowledge, a monomer capable of forming a (co) polymer having a higher Tg than the pressure-sensitive resin of the pressure-sensitive adhesive layer (B) is used. It is very easily possible by selecting or by choosing the copolymerization ratio of the monomers. Further, by blending a high Tg resin into the adhesive resin of the adhesive layer (B),
Can be adopted without any problem. However, while increasing the Tg significantly increases the creep properties, it lowers the tensile elongation. Therefore, the Tg of the adhesive resin is such that the resulting multilayer adhesive structure has a tensile elongation of 100% or more,
Preferably, it is necessary to determine it appropriately within the range of maintaining 400% or more.

The multilayer pressure-sensitive adhesive structure of the present invention is composed of two or more types of pressure-sensitive adhesive layers, and thus has various configurations depending on the actual application.

[0056]

(1) In the case of a three-layer pressure-sensitive adhesive structure It is the most preferable structure for the present invention. FIG. 1 shows a structure in which a toughened pressure-sensitive adhesive layer (A) is used as an inner layer, and a pressure-sensitive adhesive layer (B) is laminated on both sides thereof. FIG. 2 shows the pressure-sensitive adhesive layer (A).
The adhesive layer (B) and the adhesive layer (B ′) having a different adhesive resin from the adhesive layer (B) are laminated on both sides of the adhesive layer. FIG. 3 shows a structure in which an adhesive layer (C) is laminated on only one side of the adhesive layer (A), and an adhesive layer (B) is further laminated on the adhesive layer (C).

(2) Four or More Layers of Pressure-Sensitive Adhesive Structure FIGS. 4 and 5 show an embodiment of the present invention comprising four or more pressure-sensitive adhesive layers. FIG. 4 shows that the toughened pressure-sensitive adhesive layer (A) is used as an inner layer, and different pressure-sensitive adhesive layers (B) and (B ′) are laminated via different pressure-sensitive adhesive layers (C) and (C ′). To form the outermost layers on both sides of the multilayer pressure-sensitive adhesive structure.

FIG. 5 shows that two different toughened pressure-sensitive adhesive layers (A) and (A ′) are bonded via a pressure-sensitive adhesive layer (C), and a pressure-sensitive adhesive layer (B) is provided on both sides thereof. Are laminated to form outermost layers on both sides of the multilayer pressure-sensitive adhesive structure.

The multilayer pressure-sensitive adhesive structure of the present invention is characterized by being substantially free of bubbles. If air bubbles are contained, the surface smoothness of the multilayer pressure-sensitive adhesive structure tends to be impaired, so that the adhesive force is insufficient, and the multilayer pressure-sensitive adhesive structure is easily affected by the external environment such as water absorption and moisture absorption, and the adhesive properties are stable for a long time. In addition, if the pressure during use is too high, dents are formed and the parts are difficult to restore, and there are various problems such as partial adhesion failure. Become. Note that the phrase “substantially contains no bubbles” does not exclude the presence of bubbles to such an extent that these problems do not occur.

In the present invention, the tensile elongation of the multilayer pressure-sensitive adhesive structure needs to be 100 to 5000%, preferably 300 to 5000%, more preferably 400 to 4000%.
When the tensile elongation is less than the lower limit, the adhesive strength generally tends to be insufficient, and the applicability of the curved surface is deteriorated, so that the object of the present invention may not be achieved.
On the other hand, if the upper limit is exceeded, the creep performance according to the present invention cannot be generally maintained, which is not preferable.

The thickness of each pressure-sensitive adhesive layer in the multilayer pressure-sensitive adhesive structure of the present invention is generally 50 to 5000 for the pressure-sensitive adhesive layers (A) and (A ′).
μ, preferably about 100 to 3000 μ, adhesive layer (B), (B ′)
The thickness of the pressure-sensitive adhesive layers (C) and (C ′) is generally 10 to 500 μm, preferably about 10 to 100 μm.

For producing the multilayer pressure-sensitive adhesive structure of the present invention, any conventionally known method is employed. That is, for example, an organic solvent solution of an acrylic adhesive resin, a mixture obtained by mixing a filler or a crosslinking agent according to the toughening method, is applied on release paper using a doctor blade or the like, and dried according to a standard method, Cured if necessary, further laminated if necessary to form a pressure-sensitive adhesive layer to be a pressure-sensitive adhesive layer (A), and the same or different acrylic adhesive resin organic solvent solution as it is, or If necessary, add a cross-linking agent in a range such that the degree of cross-linking does not become larger than in the case of forming the pressure-sensitive adhesive layer for the pressure-sensitive adhesive layer (A), apply and dry on release paper in the same manner, and if necessary, The pressure-sensitive adhesive layer to be cured and laminated to form the pressure-sensitive adhesive layer (B) or the pressure-sensitive adhesive layer (C) is formed. The obtained pressure-sensitive adhesive layer
(A), (B) and (C) according to the intended use, the pressure-sensitive adhesive layer (B) is laminated so that it is the outermost layer on at least one side of the intended multilayer pressure-sensitive adhesive structure of the present invention Obtain a multilayer adhesive structure.

The pressure-sensitive adhesive layer obtained as described above
A method of applying and drying a pressure-sensitive adhesive resin solution for the pressure-sensitive adhesive layer (B) on one or both surfaces of (A), and curing and laminating as necessary can also be adopted. Further, a radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin can be used as the adhesive resin.

Examples of the adherend to which the multilayer pressure-sensitive adhesive structure of the present invention can be preferably used include paper; textile products such as woven fabric, knitted fabric and non-woven fabric; iron, steel, stainless steel, zinc, and the like. Various metal materials such as tin, tin, copper, brass, aluminum and duralumin; wood; thermoplastic resins such as polyvinyl chloride, thermoplastic polyester, polyamide, polystyrene, polycarbonate resin, thermoplastic polyurethane; phenolic resin, melamine resin, urea Thermosetting resins such as resins and unsaturated polyester resins; inorganic materials such as glass, ceramics, slate, mortar, and concrete; and the like.

Specifically, the multilayer pressure-sensitive adhesive structure is formed from the above adherend such as a nameplate, a rock wool plate, a gypsum board, a sign, a display character, a home appliance part, and a side molding of a vehicle such as an automobile. It can be used by pasting it on the surface of the formed body by a conventionally known method, for example, a roll pressing method, and then pasting it on another adherend.

[0067]

According to the present invention, at least one pressure-sensitive adhesive layer (A) is relatively toughened with respect to the pressure-sensitive adhesive layer (B) which is the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure. The multilayer pressure-sensitive adhesive structure is substantially free of bubbles, and has a tensile elongation of 100 to 5,000%. Thus, a structure having excellent adhesive properties, such as adhesive strength, creep characteristics, and applicability to a curved surface, which could not be achieved by the conventional technique, was obtained without being affected by the physical properties.

A conventional pressure-sensitive adhesive sheet containing air bubbles and glass balloons has unstable adhesive properties due to external conditions such as breakage of air bubbles and glass balloons during production or use due to pressure exceeding the limit. However, the multilayer pressure-sensitive adhesive structure of the present invention has excellent and stable pressure-sensitive adhesive properties.

The pressure-sensitive adhesive structure of the present invention is also epoch-making in that it can be performed extremely stably without complicated steps such as a foaming step and a step of mixing and dispersing hollow bodies such as glass balloons during production. .

Further, in the multilayer pressure-sensitive adhesive structure of the present invention, all the layers are composed of a pressure-sensitive adhesive, so that the structure is sufficiently adapted to curved surfaces and has excellent adhesiveness.

[0071]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, the measuring method of physical properties is as follows.

(1) Tensile elongation Based on JIS Z 0237.

(2) Shear strength Two aluminum plates (thickness 0.8 mm, width 25.4 mm, length
100mm) with a 25.4mm x 25.4mm multilayer adhesive structure (double-sided adhesive tape), and apply a 10kg load to the adhesive surface
Minutes, and then allowed to stand in a standard condition (23 ° C., 65% RH) for 72 hours, and then pulled at a speed of 50 mm / min under the standard condition to measure the shear strength, which was used as a measure of creep characteristics.

(3) Adhesive force A 180 ° peel strength was measured in accordance with JIS Z 0237.

Example 1 butyl acrylate (BA) / acrylic acid (AA) [weight ratio
90/10: weight average molecular weight (hereinafter sometimes simply referred to as molecular weight) 65 × 10 ⁴ : Tg = −46 ° C.] Acrylic adhesive resin solution composed of a copolymer (about 34% by weight of ethyl acetate / toluene mixed Liquid) 100 parts by weight and an isocyanate compound (trimethylolpropane adduct of tolylene diisocyanate: about 45% by weight ethyl acetate solution) as a crosslinking agent 2.5
After thoroughly mixing 20 parts by weight of ethyl acetate and 20 parts by weight of ethyl acetate, an ethylene / acrylic acid copolymer [“EA 209” (trade name), Sumitomo Seika Co., Ltd. is used as a filler according to the toughening method (1).
20% by weight (adhesive layer)
(24% by volume in (A)), mixed well and defoamed, coated on a release paper, dried sufficiently at room temperature for about 24 hours, and dried at 100 ° C. for 3 minutes. Laminate the obtained pressure-sensitive adhesive layer as necessary,
An adhesive layer (A) having a thickness of about 1 mm was obtained. Obtained pressure-sensitive adhesive layer (A)
Had flexibility and the ethylene / acrylic acid copolymer was uniformly dispersed.

Next, using the same acrylic adhesive resin solution as above, the composition obtained in the same manner as above except that the ethylene / acrylic acid copolymer as a filler was not contained was placed on a release paper. Apply and dry to obtain a 40μ thick adhesive layer,
This was laminated as a pressure-sensitive adhesive layer (B) on both sides of the pressure-sensitive adhesive layer (A) to obtain a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape). Using the obtained double-sided adhesive tape, various adhesive properties (tensile elongation,
(Shear strength, adhesive strength). Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Examples 2 to 4 and Comparative Examples 1 to 2 In Example 1, instead of using 20 parts by weight of an ethylene / acrylic acid copolymer as a filler, glass flakes (true specific gravity 2.52, standard thickness 3 to 7 μm, Standard length 100μ) 1
0 parts by weight [5% by volume in the adhesive layer (A)], mica (true specific gravity
2.8, standard thickness about 2μ, standard flake diameter about 90μ) 25 parts by weight or 71 parts by weight [20% by volume or 42 in the adhesive layer (A)]
Volume%] or activated carbon (true specific gravity 0.2, standard particle size about 50
μ) An adhesive layer (A) having a thickness of about 1 mm was obtained in the same manner as in Example 1 except that 4 parts by weight or 12 parts by weight (38% by volume or 63% by volume in the adhesive layer (A)) was used. . The obtained pressure-sensitive adhesive layer (A) had flexibility, and the filler was uniformly dispersed. Hereinafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 1, and various pressure-sensitive adhesive properties were measured in the same manner. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 5 Using the same acrylic adhesive resin as used in Example 1, the amount of the isocyanate compound as a crosslinking agent was increased to 5 parts by weight according to the toughening method (2), and the filler was used. A flexible pressure-sensitive adhesive layer (A) having a thickness of about 1 mm was obtained in the same manner as in Example 1 except that no compounding was performed. Hereinafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 1, and various pressure-sensitive adhesive properties were measured in the same manner. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 6 and Comparative Example 3 In Example 5, an isocyanate compound as a crosslinking agent was replaced with 5
Parts instead of 10 parts by weight or 2.5 parts by weight
A pressure-sensitive adhesive layer (A) having a thickness of about 1 mm was obtained in the same manner as in Example 5 except that parts by weight (the same amount as the composition for forming the pressure-sensitive adhesive layer (B)) was used. Hereinafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 1, and various pressure-sensitive adhesive properties were measured in the same manner. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 7 In Example 1, the molecular weight of the acrylic adhesive resin was changed to
Instead of using 65 × 10 ^4, a material having a molecular weight of 100 × 10 ⁴ was used in accordance with the toughening method (3). A certain pressure-sensitive adhesive layer (A) was obtained. Hereinafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 1, and various pressure-sensitive adhesive properties were measured in the same manner. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 8 In Example 7, the molecular weight of the acrylic adhesive resin was changed to
Instead of using 100 × 10 ⁴ , a thickness of about 1 mm was obtained in the same manner as in Example 1 except that a molecular weight of 110 × 10 ⁴ was used.
A flexible pressure-sensitive adhesive layer (A) was obtained. Hereinafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 1, and various pressure-sensitive adhesive properties were measured in the same manner. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 9 In Example 1, BA / A was used as the acrylic adhesive resin.
A copolymer having a weight ratio of A of 90/10 [molecular weight 65 × 10 ⁴ : Tg =
-46 ° C] instead of using BA /
AA copolymer having a weight ratio of 85/15 [molecular weight 64 × 10 ⁴ : Tg =
−39 ° C.], and a flexible pressure-sensitive adhesive layer (A) having a thickness of about 1 mm was obtained in the same manner as in Example 1 except that no filler was blended. Hereinafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 1, and various pressure-sensitive adhesive properties were measured in the same manner. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 10 In Example 9, BA / A was used as the acrylic adhesive resin.
A copolymer having a weight ratio of A of 85/15 [molecular weight 64 × 10 ⁴ : Tg =
Instead of using -39 ° C], a thickness of about 1 mm was obtained in the same manner as in Example 9 except that a copolymer having a weight ratio of BA / AA of 80/20 [molecular weight 63 × 10 ⁴ : Tg = -33 ° C] was used. A flexible pressure-sensitive adhesive layer (A) was obtained. Hereinafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 1, and various pressure-sensitive adhesive properties were measured in the same manner. Copolymer composition of the adhesive resin used,
Table 1 shows the toughening method and the results of the measurement of various adhesive properties.

Example 11 In Example 1, on one surface of the obtained pressure-sensitive adhesive layer (A), the same acrylic pressure-sensitive adhesive resin as that used for the pressure-sensitive adhesive layer (A) was used, and ethylene as a filler was used. A pressure-sensitive adhesive layer containing no acrylic acid copolymer and having a thickness of 40 μm is laminated as a pressure-sensitive adhesive layer (B), and then, on the other surface, an acrylic adhesive resin having a BA / AA weight ratio of 92/8 is used. Copolymer (molecular weight 64 × 1
0 ^4: Tg = -48 ℃] multilayer adhesive construction by laminating a pressure-sensitive adhesive layer having a thickness of 40μ containing no ethylene-acrylic acid copolymer is a filler as an adhesive layer (B ') with (Double-sided adhesive tape) was obtained. Using the obtained double-sided pressure-sensitive adhesive tape, various pressure-sensitive adhesive properties (tensile elongation, shear strength, adhesive strength) were measured. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 12 In the same acrylic adhesive resin solution as used in Example 1, 2 parts by weight of trimethylolpropane triacrylate (TMPTA) and 2-ethylhexyl carbitol acrylate (EHCA) 4 were used as monomers. Parts by weight, and 2-hydroxy-2-methyl-1-phenylpropane-
0.2 part by weight of 1-one (HMPPO) is added, and further toughening method (1)
10 parts by weight of the same glass flakes as used in Example 2 were added as a filler and mixed well to form a UV-curable composition, which was then defoamed, applied to a release paper, and irradiated with UV light. Was irradiated at 400 mJ / cm ² . The obtained pressure-sensitive adhesive layer is laminated as necessary, and a pressure-sensitive adhesive layer (A) having a thickness of about 1 mm
I got The obtained pressure-sensitive adhesive layer (A) had flexibility, and the glass flakes were uniformly dispersed.

Next, using the same acrylic adhesive resin as described above, except that the glass flakes as the filler were not contained, the composition obtained in the same manner as described above was applied onto release paper and irradiated with ultraviolet rays in the same manner. A pressure-sensitive adhesive layer having a thickness of 50 μm was obtained, and this was laminated as a pressure-sensitive adhesive layer (B) on both surfaces of the pressure-sensitive adhesive layer (A) to obtain a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape). Using the obtained double-sided pressure-sensitive adhesive tape, various pressure-sensitive adhesive properties (tensile elongation, shear strength, adhesive strength) were measured. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

Example 13 In Example 12, 2 parts by weight of TMPTA and E
Instead of using 4 parts by weight of HCA, T according to the toughening method (2)
The amount was increased to 6 parts by weight of MPTA and 12 parts by weight of EHCA, and 0.6 parts by weight of HMPPO was used instead of 0.2 parts by weight of HMPPO as a photopolymerization initiator. Thus, a pressure-sensitive adhesive layer (A) was obtained.
Thereafter, a multilayer pressure-sensitive adhesive structure (double-sided pressure-sensitive adhesive tape) was obtained in the same manner as in Example 12, and various pressure-sensitive adhesive properties were measured in the same manner. Table 1 shows the copolymer composition of the adhesive resin used, the method of toughening, and the results of various adhesive physical property measurements.

[0088]

[Table 1]

[0089]

The multilayer pressure-sensitive adhesive structure of the present invention comprises a multilayer pressure-sensitive adhesive structure comprising at least two or more pressure-sensitive adhesive layers, wherein at least one pressure-sensitive adhesive layer (A) has at least one of the multilayer pressure-sensitive adhesive structures. It is relatively tough with respect to the pressure-sensitive adhesive layer (B), which is the outermost layer on one side, and the multilayer pressure-sensitive adhesive structure contains substantially no air bubbles and has a tensile elongation of 100%.
5,000%.

The multilayer pressure-sensitive adhesive structure of the present invention is excellent in creep characteristics, adhesive strength, and applicability to a curved surface, so that it conforms well to an uneven surface or a surface having a large curvature, and does not break even when a shear force is applied. Also, since the pressure-sensitive adhesive layer contains substantially no air bubbles, it does not dent even under pressure during use and hardly absorbs water or moisture, so it maintains stable adhesive properties for a long time It has excellent performance that it can be used as an adhesive tape and sheet for fixing various molded objects such as side moldings of automobiles, interior materials for building materials, exterior materials, electric components, signboards, display panels, etc. In addition to being used, it can be used for a wide range of purposes.

[Brief description of the drawings]

FIG. 1 is an example of a multilayer pressure-sensitive adhesive structure (three layers) most suitable for the present invention. An adhesive (A) is used as an inner layer, and an adhesive layer (B) is laminated on both sides thereof.

FIG. 2 is an example of a multilayer pressure-sensitive adhesive structure (three layers) most suitable for the present invention. An adhesive (A) is used as an inner layer, and an adhesive layer (B) and an adhesive layer (B ′) are laminated on both sides thereof.

FIG. 3 is an example of a multilayer pressure-sensitive adhesive structure (three layers) most suitable for the present invention. The pressure-sensitive adhesive layer (C) is laminated on only one side of the pressure-sensitive adhesive layer (A), and the pressure-sensitive adhesive layer (B) is further laminated on the pressure-sensitive adhesive layer (C).

FIG. 4 is an example of the multilayer pressure-sensitive adhesive structure (five layers) of the present invention. The pressure-sensitive adhesive layer (A) is used as an inner layer, and the different pressure-sensitive adhesive layers (B) and (B ′) are laminated through different pressure-sensitive adhesive layers (C) and (C ′) to form a multilayer pressure-sensitive adhesive structure. It is the outermost layer on both sides.

FIG. 5 is an example of a multilayer pressure-sensitive adhesive structure (five layers) of the present invention. Adhesive layers (A) and (A ') are joined via an adhesive layer (C), and an adhesive layer (B) is laminated on both sides thereof to form outermost layers on both sides of a multilayer adhesive structure. It is.

FIG. 6 is the same as FIG.

FIG. 7 is the same as FIG. 5

[Explanation of symbols]

(A) ... toughened pressure-sensitive adhesive layer (A ') ... toughened pressure-sensitive adhesive layer different from the above-mentioned pressure-sensitive adhesive layer (A). (B)... The pressure-sensitive adhesive layer that forms the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure. (B ′)... The pressure-sensitive adhesive layer serving as the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure, which is different from the pressure-sensitive adhesive (B). (C) ·········· Different from the above four types. (C ′)... Different from the above five types.

Claims (1)

(57) [Claims] (1) at least three layers composed of only an acrylic pressure-sensitive adhesive layer
In the above multilayer pressure-sensitive adhesive structure, at least two or more
A pressure-sensitive adhesive layer, wherein at least one pressure-sensitive adhesive layer (A) is relatively toughened with respect to the pressure-sensitive adhesive layer (B) which is the outermost layer on at least one side of the multilayer pressure-sensitive adhesive structure Wherein the multilayer pressure-sensitive adhesive structure is substantially free of bubbles and has a tensile elongation of 100 to 5000%.