JP7164299B2 - Pressure-sensitive adhesive layer, and adhesive tape and composition using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive layer obtained by curing an adhesive composition, and an adhesive tape and a composition using the same.

Adhesive tapes and pressure-sensitive adhesive tapes are easier to apply than adhesives and are superior in application speed, so they are used in various fields such as construction materials such as mortar, electronic devices, textile materials such as textiles and knitted fabrics. It is In particular, construction materials and fiber materials often have rough surfaces, so in these applications, the conformability to rough surfaces and adhesive strength are improved by providing a pressure-sensitive adhesive layer on the base material. . As such an adhesive tape or adhesive tape, for example, Patent Document 1 describes a pressure-sensitive adhesive tape in which specific glass microbubbles (hollow microspheres) are contained in an adhesive layer.

Further, adhesive tapes used for construction are generally required to be excellent in flame retardancy in many cases. Furthermore, adhesive tapes used for fiber materials are also required to be flame retardant when used as interior materials in the field of transportation, such as automobiles, airplanes, and railroad vehicles. For example, in Patent Document 2, a flame retardant filler made of acrylic polymer resin and a metal hydroxide such as aluminum hydroxide is included, and the content of monomers remaining in the production process of the adhesive is specified. Adhesives are mentioned. In this pressure-sensitive adhesive, the flame retardancy of the pressure-sensitive adhesive is improved by setting the monomer content to 2% by weight or less.

Japanese Patent Publication No. 57-17030 Japanese Patent Publication No. 2007-513216

However, Patent Literature 1 does not sufficiently consider flame retardancy. On the other hand, as in Patent Document 2, there is a limit to improving the flame retardancy only by reducing the content of the monomer, and it is required to improve the flame retardancy by other means. .
The present invention has been made in view of the above-mentioned problems, and provides good adhesiveness to various adherend surfaces such as rough surfaces typified by building materials such as mortar and fiber materials such as woven fabrics and knitted fabrics. The present invention provides a pressure-sensitive adhesive layer having an excellent flame retardancy, and an adhesive tape and a composition using the pressure-sensitive adhesive layer.

The gist of the present invention is the following [1], [2] and [3].
[1] Tensile storage modulus at 23° C. containing 1.0 to 60 parts by mass of non-halogen phosphate ester flame retardant (B) per 100 parts by mass of (meth)acrylate polymer (A) is 5×10 ⁴ to 7×10 ⁷ Pa, the temperature at which the tensile storage modulus is 1×10 ⁴ Pa is 205° C. or less, and the amount of residual monomer is 0.5% by mass or less. layer.
[2] An adhesive tape comprising a substrate and the pressure-sensitive adhesive layer on at least one surface of the substrate.
[3] A structure comprising the pressure-sensitive adhesive layer and a sheet material having an uneven surface, wherein the pressure-sensitive adhesive layer is provided on the uneven surface.

INDUSTRIAL APPLICABILITY According to the present invention, a pressure-sensitive adhesive layer having good adhesiveness to various adherend surfaces and excellent flame retardancy, an adhesive tape using the pressure-sensitive adhesive layer, and a composition are provided. be able to.

The pressure-sensitive adhesive layer of the present invention contains 1.0 to 60 parts by mass of a non-halogen phosphate flame retardant (B) with respect to 100 parts by mass of a (meth)acrylate polymer (A). and its tensile storage modulus is 5×10 ⁴ to 7×10 ⁷ Pa at 23°C. Further, the tensile storage elastic modulus decreases as the temperature increases. The temperature at which ⁴ Pa is reached is 205° C. or less.

When the tensile storage elastic modulus at 23°C is outside the above range, the pressure-sensitive adhesive layer becomes difficult to exhibit sufficient adhesiveness. In addition, when the temperature at which the tensile storage elastic modulus is 1×10 ⁴ Pa is 205° C. or lower, flame retardancy is improved. Although the principle is not clear, it is presumed as follows. When the pressure-sensitive adhesive layer is heated, its fluidity increases, and when the pressure-sensitive adhesive layer is further heated from that state, a part of the pressure-sensitive adhesive layer drips. When the dripping temperature is lowered, the dripped material burns first, and the addition of the flame retardant (B) prevents the entire pressure-sensitive adhesive layer from burning. It is presumed that the flame retardancy of the pressure-sensitive adhesive layer is improved. When the tensile storage modulus of the pressure-sensitive adhesive layer is 1× ^{10 4} Pa or less, the pressure-sensitive adhesive layer is in a softened or fluidized state. It is presumed that the above-described dropping temperature is lowered, and the flame retardancy of the pressure-sensitive adhesive layer is improved. On the other hand, when the temperature at which the tensile storage modulus becomes 1×10 ⁴ Pa is higher than 205° C., the flame retardancy is not sufficiently improved.

From the viewpoint of improving the adhesiveness, the tensile storage modulus of the pressure-sensitive adhesive layer at 23° C. is preferably 1×10 ⁵ to 6×10 ⁷ Pa, more preferably 3×10 ⁵ to 5×10 ⁷ . Pa, more preferably 3.5×10 ⁵ to 8×10 ⁵ Pa.
Moreover, the temperature at which the tensile storage modulus becomes 1×10 ⁴ Pa is preferably 200° C. or less in order to further improve flame retardancy. On the other hand, the lower limit of the temperature at which the tensile storage modulus becomes 1×10 ⁴ Pa is not particularly limited, but practically, it is preferably 160° C. or higher, more preferably 170° C. or higher, and further preferably 180° C. or higher. preferable.
The temperature at which the tensile storage modulus becomes 1×10 ⁴ Pa can be set within the above range by, for example, adjusting the weight average molecular weight of the (meth)acrylate polymer (A) as described later. is.

In the present invention, the amount of residual monomer contained in the pressure-sensitive adhesive layer is 0.5% by mass with respect to the total amount of the pressure-sensitive adhesive layer from the viewpoint of further improving the flame retardancy of the pressure-sensitive adhesive layer. Below, it is preferably 0.4% by mass or less, more preferably 0.3% by mass or less, and still more preferably 0.25% by mass or less. The lower limit of the amount of residual monomers is not particularly limited, but may be 0% by mass (that is, undetected) or more.
The amount of residual monomers substantially means the amount of unreacted polymerizable monomer (a) contained in the pressure-sensitive adhesive layer. In addition, the amount of residual monomer is measured with a gas chromatograph device for the sample liquid to be measured, and a calibration prepared in advance based on the main component standard of the polymerizable monomer (a) with the largest amount (mass) blended It can be determined based on the line, and the details are as shown in the examples.
The amount of residual monomers can be determined, for example, by manufacturing the pressure-sensitive adhesive layer by the manufacturing method described later, and by appropriately adjusting the presence or absence of the photopolymerization initiator, the amount of the photopolymerization initiator used, the ultraviolet irradiation conditions, and the like. Although it is possible to reduce the amount of the monomer, it is preferable to reduce it by adjusting the ultraviolet irradiation conditions. Polymers are generally polymerized by increasing the intensity of light irradiation or by prolonging the irradiation time of ultraviolet rays. In order to reduce the amount of residual monomers, it is preferable to lengthen the irradiation time of ultraviolet rays.

<(Meth)acrylic acid ester polymer (A)>
The (meth)acrylic acid ester polymer (A) can be obtained, for example, by polymerizing a pressure-sensitive adhesive composition containing the following polymerizable monomer (a), and a polymer of the following polymerizable monomer (a) be.

[Polymerizable monomer (a)]
Examples of the polymerizable monomer (a) include (meth)acrylic acid alkyl ester-based monomers. In this specification, "(meth)acrylic acid alkyl ester" means "acrylic acid alkyl ester or methacrylic acid alkyl ester". The same is true for other similar terms.
[(Meth)acrylic acid alkyl ester-based monomer]
The (meth)acrylic acid alkyl ester-based monomer in the present invention is an ester of (meth)acrylic acid and an aliphatic alcohol, and the number of carbon atoms in the alkyl group of the aliphatic alcohol is preferably 2 to 14, more preferably Alkyl esters derived from fatty alcohols in which the is 4-10 are preferred. When the number of carbon atoms in the alkyl group is within the above range, the glass transition temperature (Tg) of the pressure-sensitive adhesive layer does not become too high and the adhesive strength is improved. In addition, it becomes easy to adjust the tensile storage modulus at 23° C. and the temperature at which the tensile storage modulus is 1×10 ⁴ Pa within the above ranges.

Specific (meth)acrylic acid alkyl ester-based monomers include, for example, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate. , t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate and the like.
Among these, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and n-octyl (meth)acrylate are preferred, and 2-ethylhexyl (meth)acrylate is more preferred.
The (meth)acrylic acid alkyl ester-based monomers may be used alone or in combination of two or more.

The content of the (meth)acrylic acid alkyl ester-based monomer in the polymerizable monomer (a) is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 88% by mass or more. is 99% by mass or less, more preferably 97% by mass or less, and still more preferably 95% by mass or less. By setting the content within the above range, it becomes easier to adjust the tensile storage modulus at 23° C. and the temperature at which the tensile storage modulus is 1×10 ⁴ Pa within the above range. It is also possible to improve the adhesive strength of the pressure-sensitive adhesive layer.

[Polar group-containing monomer]
In the present invention, the Tg of the pressure-sensitive adhesive layer, the tensile storage modulus at 23° C., and the temperature at which the tensile storage modulus is 1×10 ⁴ Pa are adjusted, and the cohesive strength of the pressure-sensitive adhesive layer , a polar group-containing monomer may be used as the polymerizable monomer (a). The polar group-containing monomer is preferably used in combination with the (meth)acrylic acid alkyl ester-based monomer described above.
Examples of polar group-containing monomers include (meth)acrylic acid and carboxylic acids containing a vinyl group such as itaconic acid;
2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone-modified (meth)acrylate, polyoxyethylene (meth)acrylate, and polyoxypropylene (meth)acrylate A vinyl monomer having a hydroxyl group such as;
(Meth)acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyllauryllactam, (meth)acryloylmorpholine, (meth)acrylamide, dimethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxy Nitrogen-containing vinyl monomers such as methyl (meth)acrylamide and dimethylaminomethyl (meth)acrylate are included.
Among these, vinyl group-containing carboxylic acids such as (meth)acrylic acid and itaconic acid are preferred, (meth)acrylic acid is more preferred, and acrylic acid is even more preferred.
These polar group-containing monomers may be used alone or in combination of two or more.

When the polymerizable monomer (a) contains a polar group-containing monomer, the content thereof in the polymerizable monomer (a) is preferably 1% by mass or more, more preferably 2% by mass or more, and still more preferably 3% by mass. More preferably, it is 4% by mass or more, and preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. By adjusting the content of the polar group-containing monomer within the above range, the tensile storage modulus at 23° C. and the temperature at which the tensile storage modulus is 1×10 ⁴ Pa can be easily controlled within the above range. Moreover, it becomes easy to improve the adhesive strength of a pressure-sensitive adhesive layer.

[Other monomers]
As the polymerizable monomer (a), monomers other than the (meth)acrylic acid alkyl ester-based monomer and the polar group-containing monomer may be used from the viewpoint of adjusting the viscosity of the pressure-sensitive adhesive composition.
Other monomers include, for example, styrenic monomers such as styrene, α-methylstyrene, o-methylstyrene, and p-methylstyrene.

When the polymerizable monomer (a) contains other monomers, the content thereof is preferably 0.5% by mass or more, more preferably 1% by mass or more, from the viewpoint of adjusting the viscosity of the pressure-sensitive adhesive composition. , and preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and even more preferably 2% by mass or less.

[Mass average molecular weight]
The (meth)acrylate polymer (A) preferably has a mass average molecular weight of 500,000 to 1,500,000. By setting the mass average molecular weight of the (meth)acrylic acid ester polymer (A) within such a range, the tensile storage modulus at 23° C. and the temperature at which the tensile storage modulus becomes 1×10 ⁴ Pa It becomes easier to adjust within the above range.
The (meth)acrylate polymer (A) has a mass average molecular weight of preferably 600,000 or more, more preferably 700,000 or more, even more preferably 800,000 or more, and more preferably 1,400,000 from the above viewpoint. 1,300,000 or less, more preferably 1,100,000 or less, and most preferably 1,000,000 or less.
In the present specification, the mass average molecular weight of the (meth)acrylic acid ester polymer (A) is measured by gel permeation chromatography (GPC) and refers to a value converted using a standard polystyrene calibration curve. . In addition, the mass average molecular weight of the (meth)acrylic acid ester polymer (A) is the uncrosslinked (meth)acrylic acid ester polymer (A) when crosslinked with a crosslinking agent described later. means the weight average molecular weight of , and its measurement method may be carried out, for example, in accordance with the examples described later.
More specifically, the polymer obtained by polymerizing only the polymerizable monomer (a) under the same conditions (the same type and amount of the photopolymerization initiator and the same curing conditions) as when producing the pressure-sensitive adhesive layer is measured. weight average molecular weight. Therefore, even when the pressure-sensitive adhesive composition contains a cross-linking agent, the mass-average molecular weight is measured for the polymerizable monomer (a) polymerized without containing the cross-linking agent.

[Gel fraction]
The gel fraction of the pressure-sensitive adhesive layer is preferably 40% by mass or more and 70% by mass or less.
By setting the gel fraction within the above range, it becomes easier to adjust the tensile storage modulus at 23° C. and the temperature at which the tensile storage modulus is 1×10 ⁴ Pa within the above range. Moreover, it becomes easy to improve the adhesive strength of a pressure-sensitive adhesive layer, and it suppresses that flexibility falls.
From the above viewpoint, the gel fraction of the pressure-sensitive adhesive layer is more preferably 45% by mass or more, still more preferably 50% by mass or more, more preferably 65% by mass or less, still more preferably 60% by mass or less. . The gel fraction can be calculated from the following formula (1).
Gel fraction (% by mass) = (B/A) x 100 Formula (1)
A: Weight of the pressure-sensitive adhesive layer (test piece) B: The pressure-sensitive adhesive layer (test piece) was immersed in tetrahydrofuran at 40°C for 48 hours, and then the dry weight of the undissolved portion of the pressure-sensitive adhesive layer.

[Swelling degree]
The degree of swelling of the pressure-sensitive adhesive layer is preferably 30 or more and 80 or less. By setting the degree of swelling within the above range, it becomes easier to adjust the tensile storage modulus at 23°C within the above range. Moreover, by making it more than a lower limit, it becomes easy to improve the adhesive strength of a pressure-sensitive adhesive layer, and by making it below an upper limit, it becomes easy to suppress the fall of the flexibility of a pressure-sensitive adhesive layer. From the above viewpoint, the degree of swelling is more preferably 35 or more, more preferably 40 or more, still more preferably 45 or more, and more preferably 75 or less. In addition, swelling degree can be calculated from the following formula (2).
Degree of swelling = C/D Formula (2)
C: 0.05 g of the pressure-sensitive adhesive layer (test piece) and 40 ml of tetrahydrofuran were placed in a 50 ml sample bottle, swollen with a shaker for 12 hours, and measured after separating the filtrate from the solid with a #200 metal mesh. Solid weight D: Solid weight measured after drying the pressure-sensitive adhesive layer (test piece) at 110 ° C. for 3 hours or more and allowing to cool

[Crosslinking agent]
The (meth)acrylic acid ester polymer (A) is crosslinked with a crosslinking agent from the viewpoint of improving the cohesive force of the pressure-sensitive adhesive layer and from the viewpoint of adjusting the gel fraction of the pressure-sensitive adhesive layer. is preferred.
Examples of the cross-linking agent include those having two or more vinyl groups, preferably polyfunctional (meth)acrylates having two or more (meth)acryloyl groups. Such a cross-linking agent is incorporated into the main chain of the (meth)acrylate polymer (A) and cross-links the main chains to form a network.
Specific cross-linking agents include hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, tris(2-hydroxyethyl)isocyanate. Nurate triacrylate, ethoxylated trimethylolpropane triacrylate, proxied trimethylolpropane triacrylate, proxied glyceryl triacrylate, neopentyl glycol adipate diacrylate, polyurethane acrylate, epoxy acrylate, polyester acrylate, and liquid hydrogenated 1,2- polybutadiene diacrylate and the like.
Among these, a cross-linking agent having a molecular weight of 400 or more is preferable. Specifically, polyurethane acrylate, polyester acrylate, and liquid hydrogenated 1,2-polybutadiene diacrylate are preferable, and liquid hydrogenated 1,2-polybutadiene diacrylate is preferable. is more preferred.

When the (meth)acrylate polymer (A) is crosslinked with a crosslinking agent, the amount of the crosslinking agent relative to 100 parts by weight of the polymerizable monomer (a) is preferably 0.1 parts by mass or more, more preferably It is 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 5 parts by mass or less, more preferably 2 parts by mass or less. By adjusting the amount of the cross-linking agent within these ranges, it is possible to improve the adhesive strength of the pressure-sensitive adhesive and to easily obtain a pressure-sensitive adhesive having an appropriate gel fraction.

[Method for producing (meth)acrylate polymer (A)]
The method for producing the (meth)acrylic acid ester polymer (A) is not particularly limited. It can be produced by irradiating with light to polymerize.
<Photoinitiator>
Examples of photopolymerization initiators that can be used in the present invention include ketones such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone [trade name: Darocure 2959, manufactured by Merck &Co.]; α-hydroxy-α,α-dimethyl-acetophenone [trade name: Darocure 1173, manufactured by Merck & Co.], methoxyacetophene, 2,2-dimethoxy-2-phenylacetophene [trade name: Irgacure 651, manufactured by BASF], and Acetophenone series such as 2-hydroxy-2-cyclohexylacetophenone [trade name: Irgacure 184, manufactured by BASF]; ketal series such as benzyl dimethyl ketal; .

The amount of the photopolymerization initiator relative to 100 parts by mass of the polymerizable monomer (a) is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, from the viewpoint of reducing the amount of residual monomers described later. It is preferably 0.2 parts by mass or more, particularly preferably 0.4 parts by mass or more, and preferably 5 parts by mass or less from the viewpoint of preventing a large amount of the photopolymerization initiator from remaining in the pressure-sensitive adhesive layer. , more preferably 3 parts by mass or less, and still more preferably 2 parts by mass or less.

<Halogen-free phosphate flame retardant (B)>
In the present invention, a non-halogen phosphate flame retardant is used for the purpose of improving the flame retardancy of the pressure-sensitive adhesive layer.
Examples of non-halogen phosphate flame retardants include non-halogen phosphates, non-halogen condensed phosphates, and the like, and it is preferable to use non-halogen condensed phosphates.
Non-halogen phosphate flame retardants include, for example, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, dimethylethyl phosphate, methyldibutyl phosphate, ethyldipropyl phosphate, hydroxyphenyldiphenyl phosphate, resorcinol bisdiphenyl phosphate, bisphenol A bisdiphenyl phosphate, resorcinol bisdi-2,6-xylenyl phosphate and these with various substituents Examples include substituted compounds.
Among these, one or more selected from hydroxyphenyldiphenyl phosphate, resorcinol bisdiphenyl phosphate, bisphenol A bisdiphenyl phosphate, and resorcinol bisdi-2,6-xylenyl phosphate are preferable, and resorcinol bisdiphenyl phosphate, bisphenol A bis More preferably, one or more selected from diphenyl phosphate.

In the present invention, the content of the non-halogen phosphate ester flame retardant (B) is 1.0 to 60 parts by mass with respect to 100 parts by mass of the (meth)acrylate polymer (A). If it is less than 1.0 mass, it becomes difficult to impart sufficient flame retardancy to the pressure-sensitive adhesive layer. Moreover, when it exceeds 60 mass parts, the adhesive strength of a pressure-sensitive adhesive layer will fall.
From the viewpoint of imparting sufficient flame retardancy to the pressure-sensitive adhesive layer, the content is preferably 1.5 parts by mass or more, more preferably 2.0 parts by mass or more, and still more preferably 2.5 parts by mass or more. is. In addition, from the viewpoint of suppressing a decrease in the adhesive strength of the pressure-sensitive adhesive layer, the More preferably, it is 40.0 parts by mass or less.
In addition, since the above-mentioned polymerizable monomer (a) has good reactivity, in the present invention, "(meth)acrylic acid ester polymer (A) 100 parts by mass" and "polymerizable monomer (a) 100 parts by mass" can be regarded as the same amount. Therefore, "the amount of the non-halogen phosphate ester flame retardant (B) with respect to 100 parts by mass of the (meth)acrylic ester polymer (A)" is the amount of the (meth)acrylic ester polymer (A) It can be calculated based on the charged amount of the polymerizable monomer (a) at the time.

<Other ingredients>
The pressure-sensitive adhesive layer (ie, adhesive composition) of the present invention may contain, for example, the following components.
[Tackifying resin]
The pressure-sensitive adhesive layer of the present invention may contain a tackifying resin from the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer.
As the tackifying resin, a tackifying resin with low polymerization inhibition such as hydrogenated terpene resin, hydrogenated rosin, disproportionated rosin resin, petroleum resin, and hydrogenated petroleum resin is preferred. Among these, hydrogenated petroleum resins are preferred because if the tackifying resin has many double bonds, the polymerization reaction is inhibited.
The softening point of the tackifying resin is preferably 120° C. or higher, more preferably 125° C. or higher, from the viewpoint of improving the cohesive strength of the pressure-sensitive adhesive layer.

When the pressure-sensitive adhesive composition contains a tackifying resin, the amount of the tackifying resin relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A) (that is, 100 parts by mass of the polymerizable monomer (a)) is It is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 7 parts by mass or more, still more preferably 9 parts by mass or more, and preferably 40 parts by mass or less, more preferably 35 parts by mass or less. , more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. When the amount of the tackifying resin is within the above range, the adhesive strength of the pressure-sensitive adhesive layer is improved, and the flexibility is also improved.

[Fine particles]
The pressure-sensitive adhesive layer of the present invention may contain fine particles from the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer to a rough surface and improving the cohesive strength of the pressure-sensitive adhesive layer.
The volume-median particle size (D50) of the fine particles is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, still more preferably 15 μm or more, from the viewpoint of improving the adhesive strength to the rough surface of the pressure-sensitive adhesive layer. 20 μm or more, more preferably 25 μm or more, preferably 150 μm or less, more preferably 130 μm or less, even more preferably 120 μm or less, and even more preferably 110 μm or less, from the viewpoint of improving the cohesive strength of the pressure-sensitive adhesive layer; Even more preferably, it is 100 μm or less. In this specification, the term "volume-median particle size (D50)" means a particle size at which the cumulative volume frequency calculated as a volume fraction is 50% from the smaller particle size.

Examples of the fine particles include inorganic hollow particles such as glass balloons, shirasu balloons, and fly ash balloons, organic hollow particles made of polymethyl methacrylate, acrylonitrile-vinylidene chloride copolymer, polystyrene, phenolic resin, etc., glass beads, and silica. Examples include beads, inorganic fine particles such as synthetic mica, and organic fine particles such as polyethyl acrylate, polyurethane, polyethylene, and polypropylene.

When the pressure-sensitive adhesive layer contains fine particles, the amount of fine particles relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A) (that is, 100 parts by mass of the polymerizable monomer (a)) is From the viewpoint of improving the adhesive strength of the adhesive layer, it is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and from the viewpoint of suppressing a decrease in the cohesive strength of the pressure-sensitive adhesive layer, it is preferably It is 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less.

The pressure-sensitive adhesive composition used in the present invention may contain additives such as plasticizers, softeners, pigments, and dyes, in addition to the other components described above.

<Method for producing pressure-sensitive adhesive layer>
The method for producing the pressure-sensitive adhesive layer of the present invention is not particularly limited, but a polymerizable monomer (a), a non-halogen phosphate ester flame retardant (B), and, if necessary, a photopolymerization initiator, a cross-linking agent, etc. It is preferable to produce a pressure-sensitive adhesive layer while producing a (meth)acrylic acid ester polymer (A) by irradiating a pressure-sensitive adhesive composition containing.
Specifically describing the production method, first, one or more polymerizable monomers (a), a non-halogen phosphate ester flame retardant (B), a cross-linking agent, a photopolymerization initiator, or the like are reacted in a glass container or the like. It is put into a container to obtain an adhesive composition.
Then, in order to remove oxygen dissolved in the pressure-sensitive adhesive composition, an inert gas such as nitrogen gas is generally supplied to purge oxygen. Then, the pressure-sensitive adhesive composition is applied on a substrate made of a release sheet such as release paper, or applied to a substrate such as a plastic film, metal foil, paper, cloth, non-woven fabric, etc., and then irradiated with light to polymerize. By doing so, a pressure-sensitive adhesive layer can be obtained.
It is preferable that the process from the application or impregnation of the pressure-sensitive adhesive composition to the process of irradiating with light is carried out in an inert gas atmosphere or in a state in which oxygen is blocked by a film or the like.

Lamps that can be used to irradiate the pressure-sensitive adhesive composition with light include, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. etc. Among these, chemical lamps are preferred. The light irradiation intensity when irradiating the adhesive composition with light varies depending on the photopolymerization initiator, but is preferably about 0.1 to 100 mW/cm ² .

<Thickness of Pressure-Sensitive Adhesive Layer>
The thickness of the pressure-sensitive adhesive layer is preferably 150 μm or more, more preferably 200 μm or more, still more preferably 250 μm or more, and even more preferably 300 μm or more, from the viewpoint of ensuring the adhesive strength of the pressure-sensitive adhesive layer, From the viewpoint of improving the conformability of the pressure-sensitive adhesive layer to an adherend surface such as a rough surface, the thickness is preferably 1,000 μm or less, more preferably 950 μm or less, even more preferably 900 μm or less, still more preferably 850 μm or less, and still more preferably 850 μm or less. It is preferably 800 μm or less.

Although the pressure-sensitive adhesive layer can be used for various adherend surfaces, it is preferably a pressure-sensitive adhesive layer for rough surfaces. The "pressure-sensitive adhesive layer for rough surfaces" is used for bonding rough surfaces such as building materials and textile materials, and after placing the adhesive layer on the adherend surface, it is adhered by applying pressure. A pressure-sensitive adhesive layer that can adhere to a surface. The pressure-sensitive adhesive layer of the present invention can exhibit good adhesiveness even when the adherend surface is rough.
However, the pressure-sensitive adhesive layer can be applied to other irregular adherends, metal plates used in vehicles, acrylonitrile-butadiene-styrene copolymer synthetic resin plates (ABS plates), and polyvinyl chloride. It also exhibits excellent adhesiveness to boards (PVC boards) and the like, and can be suitably used for these materials as well.

[Adhesive tape]
The pressure-sensitive adhesive tape of the present invention comprises a substrate and the pressure-sensitive adhesive layer provided on at least one surface of the substrate.
<Base material>
The substrate used for the adhesive tape is not particularly limited, but examples include resin films such as polyethylene terephthalate, resin cloth using polyethylene terephthalate, etc., foams having an open-cell structure, polyvinyl alcohol, polyvinyl acetal, resins such as urethane. Moisture-permeable film using materials, impregnated paper, coated paper, fine paper, kraft paper, Japanese paper, synthetic paper, laminated products of these, etc. Among them, polyethylene Terephthalate film (PET film) and polyethylene terephthalate cloth (PET cloth) are preferred.

Moisture-permeable films include, for example, KTF (manufactured by Mitsubishi Plastics, Inc.), Espoir (manufactured by Mitsui Chemicals, Inc.), Porum (manufactured by Tokuyama Corporation), Tapylene MPF (manufactured by Taika Kogyo Co., Ltd.), Cellpore ( (manufactured by Sekisui Film Co., Ltd.), microporous film (manufactured by 3M Japan Corp.), PORO (manufactured by Futamura Chemical Co., Ltd.), and Hipore (manufactured by Asahi Kasei E-Materials Corp.). . In addition, mechanically craze-treated products are available as commercial products such as Monotran (manufactured by Nac Co., Ltd.).
The substrate may be a release sheet obtained by releasing one side of each of the above materials, in which case the pressure-sensitive adhesive layer may be provided on the release-treated side.

Furthermore, a release layer, an antistatic layer, or the like may be provided on the surface of the substrate opposite to the surface on which the pressure-sensitive adhesive layer is provided. When the adhesive tape is a double-sided tape having pressure-sensitive adhesive layers on both sides of a base material, a release paper or a release film may be laminated on one side of the pressure-sensitive adhesive layer.
Moreover, in order to improve the adhesion between the substrate and the pressure-sensitive adhesive layer, the substrate may be subjected to surface treatment such as corona treatment, if necessary.
The thickness of the substrate is preferably 20 μm or more, more preferably 30 to 100 μm. By setting the thickness of the base material to 20 μm or more, breakage or the like is less likely to occur during rework.

<Manufacture of adhesive tape>
The pressure-sensitive adhesive tape of the present invention can be produced by the method described in the above-described method for producing a pressure-sensitive adhesive layer. Specifically, the adhesive tape having a pressure-sensitive adhesive layer can be obtained by coating the adhesive composition on a substrate and then irradiating it with light under the conditions described above to polymerize it. Since the adhesive tape of the present invention has the pressure-sensitive adhesive layer of the present invention, it has excellent adhesiveness even when the surface to be adhered is rough, and has excellent flame retardancy.

<Component>
The structure of the present invention comprises a sheet material having unevenness and a pressure-sensitive adhesive layer provided on the surface of the sheet material having unevenness. The sheet material may have unevenness on at least one side, but may have unevenness on both sides. Sheet materials having unevenness include fibrous materials such as knitted fabrics and woven fabrics. The unevenness referred to here means, for example, microscopic unevenness based on a fiber structure such as a knitted structure or a woven structure, and excludes, for example, a portion forcibly raised from a knitted fabric or a woven fabric.
Since the pressure-sensitive adhesive layer of the present invention has high flame retardancy as described above, it is possible to impart flame retardancy to the entire structure, for example. In addition, the adhesiveness of the pressure-sensitive adhesive layer to the sheet material is improved, and the anchoring property to the uneven surface of the sheet material is also improved. That is, it is possible to prevent anchor peeling of the pressure-sensitive adhesive layer that occurs when another adherend, release sheet, or the like is peeled off from the composition. In order to improve the anchoring property while improving the flame retardancy and adhesiveness, the weight average molecular weight, gel fraction, degree of swelling, amount of the non-halogen phosphate flame retardant (B), etc. are adjusted in a well-balanced manner. do it.

The composition may be, for example, a sheet material laminated with the adhesive tape described above. In this case, if the base material of the pressure-sensitive adhesive tape is a release sheet, the structure can be attached to another adherend by the pressure-sensitive adhesive layer exposed by peeling off the release sheet. Moreover, even when the adhesive tape is a double-sided tape, it is possible to attach the composition to another adherend via the double-sided tape.
In the composition, the thickness of the sheet material is, for example, preferably 0.05 to 5 mm, more preferably 0.01 to 1.0 mm. The thickness of the sheet material is obtained, for example, by observing the sheet material with a microscope and finding the average value of the distances from one surface of the sheet material to the other surface. However, the above distance means the distance from the tip of the projection on one surface to the tip of the projection on the other surface (or the smooth surface if the surface is smooth).

Further, the height of the irregularities on the surface of the sheet material on which the pressure-sensitive adhesive layer is provided is preferably 5 to 60% of the thickness of the sheet material. In addition, below, the ratio of the uneven|corrugated height with respect to the thickness is also called "uneven|corrugated ratio." The pressure-sensitive adhesive layer of the present invention has good adhesiveness and anchoring properties even on such a surface with a large unevenness ratio. However, in order to exhibit the anchoring effect more effectively, it is more preferable that the unevenness ratio is 15 to 50%.
The unevenness height is a five-point average value of unevenness heights measured in a photograph of the cross-sectional area of the sheet material magnified 200 times with a microscope. The unevenness height is the average value of the difference in height between a concave portion and two convex portions adjacent to the concave portion in a cross-sectional photograph.

The present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples.

<Evaluation>
[Tensile storage modulus]
The tensile storage modulus at 23° C. was measured under the following measurement conditions using a storage modulus measuring device under the trade name “DVA-200/L2” manufactured by IT Keisoku Co., Ltd. Further, the temperature at which the tensile storage modulus becomes 1×10 ⁴ Pa was measured by increasing the temperature at the following set heating rate and measuring the temperature at which the tensile storage modulus becomes 1×10 ⁴ Pa.
(Measurement condition)
Gauge length: 3 cm Sample width: 0.6 cm Sample thickness: 0.2 cm
Deformation mode: Tensile Static/dynamic stress ratio: 1.5 Set strain: 0.10%
Set temperature rise rate: 10°C/min Measurement frequency 10Hz

[Gel Fraction and Swelling Degree of Pressure-Sensitive Adhesive Layer]
The gel fraction and swelling degree of the pressure-sensitive adhesive layer were measured according to the methods described in the specification.
[Thickness of Pressure-Sensitive Adhesive Layer]
The thickness of the pressure-sensitive adhesive layer was measured with a dial gauge (manufactured by Mitutoyo).
[Mass average molecular weight]
The mass average molecular weight of the (meth)acrylate polymer (A) was measured by gel permeation chromatography (GPC) and calculated using a standard polystyrene calibration curve.
The weight average molecular weight is the (meth)acrylic obtained by curing only the polymerizable monomer (a) under the same conditions (the same type and amount of the photopolymerization initiator, and the same curing conditions) as in each example and comparative example. It is the mass average molecular weight measured for the acid ester polymer (A).

[Residual monomer amount]
The amount of residual monomer was measured in the following manner.
(1) Preparation of calibration curve Acetone solutions of 2-ethylhexyl acrylate with concentrations of 0.001% by mass, 0.0003% by mass, and 0.0001% by mass were prepared, and the following was performed using a gas chromatograph (Agilent 6890A and 7820A). Measurement was performed under the measurement conditions to measure the area. A straight line with H as the vertical axis and W as the horizontal axis, which was created from the measurement area H of each concentration solution and the weight W of 2-ethylhexyl acrylate per 1 mL, was used as a calibration curve. However, when the correlation coefficient of the straight line did not reach 0.99 or more, the measurement was performed again and the calibration curve was prepared again.
(2) Preparation of sample solution 0.4 g of pressure-sensitive adhesive layer to be measured and 10 mL of acetone were placed in a test tube, and residual monomers were extracted at room temperature for 12 hours. 1 mL of the resulting extract was collected in a vial, and the vial was set in an autosampler.
(3) Measurement of residual monomer amount The above sample solution was measured using a gas chromatograph (Agilent 6890A and 7820A) under the following measurement conditions. The mass % residual monomer of the reaction was calculated.
(residual monomer weight) ÷ (sample weight per mL) x 100
(4) Measurement conditions Column filler: polysiloxane polymer (DB-624 manufactured by Agilent Technologies)
Carrier: Chromosorb W Column size: 180 μm × 20 m
Detector: FID (flame ionization detector) Carrier gas: Helium Carrier gas flow rate: 1 mL/min Column temperature: 260°C
Inlet temperature: 250°C

[Combustion test]
After cutting the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples into a size of 5 cm×10 cm, the PET film was peeled off to obtain a test piece. This test piece is attached to a metal frame and suspended in an 18-liter can, and an 8 cm flame of a power torch is applied to the lower end of the test piece for 12 seconds. B was assigned to self-extinguishing when a flame of 4 cm from an ignition lighter was applied for 12 seconds. Also, C indicates that the flame does not self-extinguish under any conditions. In addition, self-extinguishing means extinguishing before burning to the end of the sample.

[Ball tack test]
A ball tack test was carried out according to JIS Z 0237. However, when even a ball of 32/32 inch stopped and did not move, the size of the ball larger than 32/32 inch was increased by increments of 1/32. The ball number "A" shown in the table indicates a ball of A/32 inches.

<Example 1>
A pressure-sensitive adhesive composition was prepared by mixing a polymerizable monomer (a), a cross-linking agent, a flame retardant, fine particles, and a photopolymerization initiator according to the formulation shown in Table 1. The adhesive composition was purged with nitrogen to remove dissolved oxygen.
Next, a spacer with a thickness of 0.5 mm is placed on a release-treated PET film with a thickness of 50 μm, the pressure-sensitive adhesive composition is applied on the PET film, and the PET film is folded so that the release-treated surface sticks. It was coated in contact with the agent composition.
In this state, the intensity of the chemical lamp was adjusted so that the PET film on the covering side had an ultraviolet irradiation intensity of 5 mW/cm ² , and the film was irradiated with ultraviolet rays for 10 minutes to obtain a pressure-sensitive adhesive layer. The thickness of the pressure-sensitive adhesive layer was 700 µm.

<Examples 2 to 5, Comparative Example 1>
Pressure-sensitive in the same manner as in Example 1, except that a pressure-sensitive adhesive composition was prepared according to the formulation shown in Table 1, and the UV irradiation time and UV intensity were adjusted so that the weight average molecular weight and residual monomers in the table were obtained. An adhesive layer was obtained.

Materials used in Examples and Comparative Examples are as follows.
Polymerizable monomer (a-1): manufactured by Mitsui Chemicals, Inc., 2-ethylhexyl acrylate polymerizable monomer (a-2): manufactured by Mitsui Chemicals, Inc., acrylic acid flame retardant (B): manufactured by Daihachi Chemical Industry Co., Ltd., CR-741 (bisphenol A bisdiphenyl phosphate)
Cross-linking agent: liquid hydrogenated 1,2-polybutadiene diacrylate, manufactured by Nippon Soda Co., Ltd., TEAI-1000
Particles: Glass balloon, manufactured by 3M Japan Co., Ltd., Glass Bubbles K-25 (D50: 55 μm)
Photopolymerization initiator: 2,2-dimethoxy-2-phenylacetophenone, manufactured by BASF, Irgacure 651

As is clear from the results of Examples, the pressure-sensitive adhesive layer of the present invention has good adhesiveness and excellent flame retardancy. On the other hand, in Comparative Example 1, the temperature at which the tensile storage modulus was 1×10 ⁴ Pa was higher than 205° C., so the flame retardancy was not sufficiently improved, and the results of the combustion test were unsatisfactory.

Claims (7)

A non-halogen phosphate flame retardant (B) is added to 100 parts by mass of a (meth)acrylic acid ester polymer (A) crosslinked by a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups. Contains 1.0 to 60 parts by mass,
The (meth)acrylic acid ester-based polymer (A) is a polymerizable monomer (a ), and the content of the carboxylic acid containing a vinyl group in the polymerizable monomer (a) is 1% by mass or more and 12% by mass or less,
contains particulates;
The tensile storage modulus at 23° C. is 5×10 ⁴ to 7×10 ⁷ Pa, and the temperature at which the tensile storage modulus is 1×10 ⁴ Pa is 205° C. or less,
A pressure-sensitive adhesive layer having a residual monomer content of 0.5% by mass or less. 1, wherein the non-halogen phosphate flame retardant (B) is selected from the group consisting of hydroxyphenyldiphenyl phosphate, resorcinol bisdiphenyl phosphate, bisphenol A bisdiphenyl phosphate, and resorcinol bisdi-2,6-xylenyl phosphate; The pressure sensitive adhesive layer of claim 1, which is at least one seed. 3. The pressure-sensitive adhesive layer according to claim 1 or 2 , wherein the pressure-sensitive adhesive layer contains a tackifying resin. A pressure-sensitive adhesive tape comprising a substrate and the pressure-sensitive adhesive layer according to any one of claims 1 to 3 on at least one surface of the substrate. 5. The pressure-sensitive adhesive tape according to claim 4, wherein the substrate is at least one selected from the group consisting of polyethylene terephthalate film and polyethylene terephthalate cloth. A structure comprising the pressure-sensitive adhesive layer according to any one of claims 1 to 3 and a sheet material having an uneven surface, wherein the pressure-sensitive adhesive layer is provided on the uneven surface. 7. The construct of claim 6, wherein said sheet material is woven or knitted.