WO2020137575A1

WO2020137575A1 - Adhesive tape

Info

Publication number: WO2020137575A1
Application number: PCT/JP2019/048657
Authority: WO
Inventors: 森川　泰宏; 晃山上
Original assignee: Dic株式会社
Priority date: 2018-12-25
Filing date: 2019-12-12
Publication date: 2020-07-02
Also published as: KR20210107626A; JP6819833B2; CN112955317A; JPWO2020137575A1

Abstract

The present invention provides an adhesive tape in which it is possible to obtain high levels of both adhesiveness and flame retardance, even when the thickness is reduced. This adhesive tape is provided with a substrate and an adhesive layer provided on one or both sides of the substrate, wherein the adhesive tape is characterized in that: the adhesive tape has a thickness of 30 μm or below when the adhesive tape is a one-sided adhesive tape; the adhesive tape has a thickness of 50 μm or below when the adhesive tape is a double-sided adhesive tape; the adhesive tape has a flame retardance of at least a level conforming to VTM-0 in a test according to UL94 standards; the adhesive layer has a thickness of 20 μm or below; and the adhesive constituting the adhesive layer contains a flame retardant in which the particle diameter D95 corresponding to cumulative 95% from the small-diameter side of the cumulative granularity distribution is 20.0 μm or below.

Description

Adhesive tape

The present invention relates to an adhesive tape.

Due to the remarkable progress of electronic technology, electric, electronic, and OA equipments have become highly integrated and high-performance, and are used for the above equipments in order to reduce or prevent the risk of ignition due to high temperature and heat accumulation inside these equipments. High pressure resistance is also required for adhesive tapes. In addition, various researches have been conducted on the flame retardancy of plastic materials in various fields such as home appliances, vehicles, and building materials, and the adhesive tape used for fixing them is also required to have high flame retardancy.
As such an adhesive tape, for example, a technique as disclosed in Patent Document 1 has been proposed, and it is said that this technique can have good flame retardancy and adhesive properties together.

Japanese Patent Laid-Open No. 11-1669

However, in recent years, for example, the higher integration and lighter weight have been advanced in the above-mentioned applications, and in the pressure-sensitive adhesive tape, not only higher flame retardancy than the conventional pressure-sensitive adhesive tape but also further thinning is required. Is coming. In order to make the pressure-sensitive adhesive tape thinner, not only the base material of the pressure-sensitive adhesive tape but also the pressure-sensitive adhesive layer must be made thinner. However, as the pressure-sensitive adhesive tape becomes thinner, the ratio of the air contact area to the tape volume increases, so that it generally becomes easier to burn. Therefore, in order to provide a pressure-sensitive adhesive tape that is both thin and flame-retardant, a flame-retardant design higher than conventional is required.

Therefore, an object of the present invention is to provide a pressure-sensitive adhesive tape that can achieve high levels of both tackiness and flame retardancy even when the thickness is reduced.

The invention of the present application is as follows.
[1] A pressure-sensitive adhesive tape comprising a base material and a pressure-sensitive adhesive layer provided on one surface or both surfaces of the base material,
The thickness of the adhesive tape is 30 μm or less when the adhesive layer is provided on one surface of the base material, and the thickness of the adhesive tape when the adhesive layer is provided on both surfaces of the base material. Is 50 μm or less,
The pressure-sensitive adhesive tape has a flame retardancy equal to or higher than VTM-0 in a test conforming to UL94 standard,
The pressure-sensitive adhesive layer has a thickness of 20 μm or less,
The pressure-sensitive adhesive tape, wherein the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer contains a flame retardant having a particle diameter D95 of particles corresponding to cumulative 95% from the smaller diameter side of the cumulative particle size distribution of 20.0 μm or less.
[2] The adhesive tape according to [1] above, wherein the flame retardant contains a phosphorus-based flame retardant.
[3] The adhesive tape according to [2] above, wherein the phosphorus-based flame retardant contains a polyphosphoric acid derivative.
[4] The adhesive tape according to [2] or [3] above, wherein the phosphorus-based flame retardant contains ammonium polyphosphate.
[5] The adhesive tape according to [4], wherein the content of ammonium polyphosphate is 65 parts by mass or more based on 100 parts by mass of the adhesive component of the adhesive.
[6] In the X-ray diffraction measurement of ammonium polyphosphate, the peak intensity value at a diffraction angle 2θ=15.5±0.2° is measured with the peak intensity value at a diffraction angle 2θ=14.6±0.2°. The adhesive tape according to [4] or [5] above, wherein the value divided by is 1.4 or more.
[7] The pressure-sensitive adhesive tape according to any of [4] to [6] above, wherein ammonium polyphosphate is classified.
[8] The adhesive tape according to any of [2] to [7] above, wherein the flame retardant further contains a metal hydride.

According to the present invention, it is possible to provide a pressure-sensitive adhesive tape capable of achieving high levels of both tackiness and flame retardancy even when the thickness is reduced.

Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the present embodiment.

"Adhesive tape"
The pressure-sensitive adhesive tape of the present embodiment comprises a base material and a pressure-sensitive adhesive layer provided on one side or both sides of the base material, in other words, a single-sided pressure-sensitive adhesive tape having adhesiveness on one side, or adhesive on both sides. It is a double-sided adhesive tape having.

The pressure-sensitive adhesive tape of the present embodiment is a thin-walled pressure-sensitive adhesive tape. Specifically, when the pressure-sensitive adhesive tape is a single-sided pressure-sensitive adhesive tape (when the pressure-sensitive adhesive layer is provided on one surface of the substrate), the thickness of the pressure-sensitive adhesive tape Is 30 μm or less, and in the case of a double-sided pressure-sensitive adhesive tape (when the pressure-sensitive adhesive layers are provided on both sides of the substrate), the thickness of the pressure-sensitive adhesive tape is 50 μm or less. In the present embodiment, when the adhesive tape is a single-sided adhesive tape, the thickness of the adhesive tape may be 25 μm or less, or may be 20 μm or less. When the pressure sensitive adhesive tape is a double-sided adhesive tape, the thickness of the adhesive tape may be 45 μm or less, or 30 μm or less.
The thickness of the adhesive tape can be measured by the method described in Examples below.

The pressure-sensitive adhesive tape of this embodiment has a flame retardancy equal to or higher than the flame retardance conforming to VTM-0 in the test according to the UL94 standard even when the thickness is reduced as described above. Therefore, the pressure-sensitive adhesive tape having a reduced thickness can have a sufficiently excellent flame retardancy. Incidentally, in order to satisfy the predetermined flame retardancy in the pressure-sensitive adhesive tape of the present embodiment, as will be described in detail later, a method using a phosphoric acid ester amide as a flame retardant, a method using an aromatic condensed phosphoric acid ester, red phosphorus Examples thereof include a method using melamine cyanurate, a method using red phosphorus, and a method using a polyphosphoric acid derivative such as ammonium polyphosphate, melamine polyphosphate, melam polyphosphate, and melem polyphosphate.
The flame retardancy of the adhesive tape can be measured by the method described in Examples below.

In the adhesive tape of the present embodiment, it is preferable that the double-sided tape has an adhesive force of 4.0 N or more and the single-sided tape has an adhesive force of 2.0 N or more as measured by the method described in Examples below.

-Base material-
In the present embodiment, the base material of the adhesive tape is not particularly limited, and examples thereof include a resin film, a non-woven fabric, paper, a metal foil, a woven fabric, a rubber sheet, a foamed sheet, and a laminate of these (in particular, a laminate including a resin film. ) And the like. Examples of the resin forming the resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene- Vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluorine resin, polyether ether ketone (PEEK) ) And the like. Examples of the non-woven fabric include non-woven fabric of natural fiber (cellulosic fiber); non-woven fabric of synthetic resin fiber such as polypropylene resin fiber, polyethylene resin fiber and polyester resin fiber. Examples of the metal foil include copper foil, stainless steel foil, aluminum foil and the like. Examples of the paper include Japanese paper and kraft paper.
As these base materials, those subjected to a treatment such as nonflammability and self-extinguishing property can also be used.

From the viewpoint of manufacturing cost, the base material is preferably a natural fiber nonwoven fabric, a synthetic resin fiber nonwoven fabric, or a polyester film. From the viewpoint of imparting flame retardancy more preferably, a polyphenylene sulfide film or a polyimide film can be used.
The thickness of the base material used for the double-sided tape is preferably 40 μm or less, more preferably 30 μm or less, and further preferably 20 μm or less from the viewpoint of reducing the thickness of the adhesive tape.
The thickness of the substrate used for the single-sided tape is preferably 25 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less, from the viewpoint of reducing the thickness of the adhesive tape.

-Adhesive layer-
In this embodiment, the pressure-sensitive adhesive layer has a thickness of 20 μm or less, and the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer contains a predetermined flame retardant together with the pressure-sensitive adhesive component. In the case of the pressure-sensitive adhesive layer having such a thickness, it is difficult for the conventional pressure-sensitive adhesive tape to achieve both adhesiveness and flame retardancy, but the adhesive tape of the present embodiment can achieve both. Further, the pressure-sensitive adhesive layer preferably has a thickness of 20 μm or less, more preferably 15 μm or less, and further preferably 11 μm or less, from the viewpoint of reducing the thickness of the pressure-sensitive adhesive tape.

--- Adhesive component ---
The pressure-sensitive adhesive component of the pressure-sensitive adhesive of the present embodiment is not particularly limited, and examples thereof include an acrylic pressure-sensitive adhesive component, a urethane pressure-sensitive adhesive component, a synthetic rubber pressure-sensitive adhesive component, a natural rubber pressure-sensitive adhesive component, and a silicone pressure-sensitive adhesive component. In this embodiment, an acrylic adhesive component is preferable because it is easy to obtain a relatively strong adhesive force.

The acrylic adhesive component is not particularly limited, but includes, for example, at least one acrylic polymer containing a (meth)acrylic acid alkyl ester monomer as a monomer unit. The (meth)acrylic acid alkyl ester monomer is, for example, a (meth)acrylic acid alkyl ester having an alkyl group having 2 to 14 carbon atoms, and examples thereof include, but are not limited to, ethyl acrylate and acryl. Propyl acrylate, butyl acrylate, isobutyl acrylate, isoamyl acrylate, hexyl acrylate, octyl acrylate, isonolyl acrylate, isodecyl acrylate, butyl methacrylate, hexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, etc. ..
In addition, in this specification, "(meth)acrylic acid alkyl ester" means acrylic acid alkyl ester or methacrylic acid alkyl ester.

The acrylic polymer may be copolymerized with a monomer having a carboxyl group or a hydroxyl group such as acrylic acid, maleic anhydride, and 2-hydroxyethyl (meth)acrylate. As a result, the constituent units derived from these monomers become crosslinking points in the acrylic polymer, and the hardness of the adhesive component can be adjusted to develop the desired adhesive force.

The acrylic polymer is not particularly limited, but for example, vinyl acetate, acrylonitrile, acrylamide, styrene, etc. may be copolymerized to adjust the cohesive force of the acrylic polymer, for example.

The acrylic polymer can be polymerized by using radical polymerization methods such as solution polymerization, suspension polymerization, emulsion polymerization and bulk polymerization without any particular limitation. Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, organic peroxides such as bis(4-tert-butylcyclohexyl)peroxydicarbonate, 2,2′-azobisisobutyronitrile, 2,2′-azobis. (2-methylbutyronitrile), dimethyl-2,2-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovalerianic acid), 2,2'-azobis(2-methylpropione) Acid) dimethyl, azobis(2,4-dimethylvaleronitrile) (AVN), and other azo-based polymerization initiators can be used.

The acrylic polymer may contain a cross-linking agent capable of cross-linking to cross-link it. Examples of the cross-linking agent include epoxy-based cross-linking agents, polyisocyanate compounds such as aliphatic diisocyanates, aromatic diisocyanates and aromatic triisocyanates. Further, for those having a slow crosslinking reaction, a crosslinking accelerator composed of an organometallic compound or the like can be added. The cohesive force can be improved by crosslinking the acrylic polymer.

--Flame retardants--
In the present embodiment, the flame retardant contained in the pressure-sensitive adhesive is not particularly limited, for example, phosphorus-based flame retardant, bromine-based flame retardant, chlorine-based flame retardant, antimony compound, nitrogen compound, boron compound, metal hydroxide , Alkaline earth metal carbonates and the like.
The phosphorus-based flame retardant is not particularly limited, and examples thereof include red phosphorus, red phosphorus derivatives such as red phosphorus melamine cyanurate, polyphosphoric acid derivatives such as ammonium polyphosphate, melamine polyphosphate, melam polyphosphate and melem polyphosphate. And phosphoric acid derivatives such as phosphoric acid ester amide and aromatic condensed phosphoric acid ester.
The flame retardants may be used alone or in combination of two or more.

Here, in the present embodiment, as described above, the thin adhesive tape has the flame retardancy equal to or higher than the flame retardance conforming to VTM-0 in the test conforming to the UL94 standard, so that it is more preferably satisfied. Therefore, it is preferable that the flame retardant contains a phosphorus flame retardant. More preferably, the phosphorus-based flame retardant contains a polyphosphoric acid derivative, and further preferably, the polyphosphoric acid derivative contains ammonium polyphosphate.

The content of the flame retardant is not particularly limited and may vary depending on the type, but is preferably 30 to 500 parts by mass, more preferably 35 to 400, and further preferably 40 to 100 parts by mass of the adhesive component. It is 300 parts by mass. By setting the content to 30 parts by mass or more, it becomes easy to satisfy the predetermined flame retardancy, while by setting the content to 500 parts by mass or less, it is possible to obtain an adhesive tape having suitable adhesive strength. it can.
Furthermore, when a polyphosphoric acid derivative is used as the flame retardant, the content of the polyphosphoric acid derivative is preferably 40 to 300 parts by mass, more preferably 45 to 2250 parts by mass, and still more preferably 100 parts by mass of the adhesive component. 50 to 200 parts by mass. By setting the content to 40 parts by mass or more, it becomes easy to satisfy the predetermined flame retardancy, while by setting the content to 300 parts by mass or less, it is possible to obtain an adhesive tape having suitable adhesive strength. it can.
Furthermore, when ammonium polyphosphate is used as the flame retardant, the content of ammonium polyphosphate is preferably 65 to 250 parts by mass, more preferably 75 to 200 parts by mass, and further preferably 100 parts by mass of the adhesive component. Is 80 to 150 parts by mass. By setting the content to 65 parts by mass or more, it becomes easy to satisfy the predetermined flame retardancy, while by setting the content to 250 parts by mass or less, it is possible to obtain an adhesive tape having suitable adhesive strength. ..

Here, in the case where the flame retardant contains ammonium polyphosphate, the peak intensity value of the diffraction angle 2θ=15.5±0.2° is determined by the diffraction angle 2θ in the X-ray diffraction measurement of ammonium polyphosphate. The value (hereinafter, also referred to as peak intensity ratio) divided by the peak intensity value of =14.6±0.2° is preferably 1.4 or more.
Ammonium polyphosphate exists in type I and type II depending on its crystalline state, and type II ammonium polyphosphate is more effective in improving flame retardancy. The peak appearing at the diffraction angle 2θ=15.5±0.2° of ammonium polyphosphate is a peak characteristically observed in the type II ammonium polyphosphate, and the diffraction angle 2θ=14.4. The peak at 6±0.2° is a peak characteristically observed in type I and type II ammonium polyphosphate. That is, by defining the peak intensity ratio as described above, the content of the type II in ammonium polyphosphate can be defined, and the contribution to flame retardancy, which is allowed in ammonium polyphosphate, can be compared. The content of type I ammonium polyphosphate is specified to be extremely low. Therefore, since the content of the type II ammonium polyphosphate present in the ammonium polyphosphate can be increased by setting the peak intensity ratio to the above relationship, even the pressure-sensitive adhesive tape having a thin pressure-sensitive adhesive layer can be used. It is possible to further secure flame retardancy.
Further, in the present embodiment, from the same viewpoint, the peak intensity value at the diffraction angle 2θ=15.5±0.2° is changed to the peak intensity value at the diffraction angle 2θ=14.6±0.2°. The divided value is preferably 1.5 or more, more preferably 1.6 or more, and further preferably 2.0 or more.
In the present embodiment, the value obtained by dividing the peak intensity value at the diffraction angle 2θ=15.5±0.2° by the peak intensity value at the diffraction angle 2θ=14.6±0.2° is From the viewpoint of the above, the larger the value, the better and the upper limit is not particularly limited.
The peak intensity value at a predetermined diffraction angle 2θ in the X-ray diffraction measurement can be measured by the method described in Examples below.

The ammonium polyphosphate is not particularly limited as long as it satisfies the above-mentioned particle size and a predetermined ratio of the diffraction angle in X-ray diffraction measurement. Can be used in the form of a free-flowing, poorly water-soluble powder coated with a melamine/formaldehyde resin or the like.

Here, for the flame retardant, the particle diameter D95 of particles corresponding to cumulative 95% from the smaller diameter side of the cumulative particle size distribution is 20.0 μm or less, preferably 19.0 μm or less, and more preferably 15.0 μm. It is as follows. By setting the particle size D95 to 20.0 μm or less, the number of particles having a relatively large particle size is reduced, so that even if the flame retardant is incompatible with the adhesive component and exists as a solid in the adhesive layer, the relatively large particles It is possible to suppress the spacer effect due to and to secure the adhesiveness even with an adhesive tape having a thin adhesive layer.
When the flame retardant contains a plurality of types of flame retardants, the plurality of types of flame retardants each satisfy a predetermined range of the particle diameter D95.

The particle diameter (D95 etc.) of the particles accumulated from the smaller diameter side of the cumulative particle size distribution and corresponding to a predetermined ratio can be measured by the method described in Examples below.

Further, in the present embodiment, the particles of the flame retardant having a particle diameter of 20 μm or more are preferably 1% by mass or less in the nonvolatile component of the flame retardant adhesive, and more preferably 0, from the viewpoint of further securing the adhesiveness. It is not more than 1% by mass, more preferably not contained.

Here, in order to satisfy the predetermined particle diameter of the flame retardant, it can be obtained by crushing and classifying the particles of the flame retardant. Specifically, the pulverizing method is not particularly limited, but is typified by a media type dispersing/pulverizing machine such as a bead mill, a ball mill, an attritor, a planetary mill or a vibration mill, a mill type grinder, and a jet mill. A non-media type dispersion/pulverizer can be used. Either a wet method or a dry method can be used as the pulverization method, but wet pulverization is preferable from the viewpoint of easy dispersibility after pulverization, good recovery of the pulverized product, and good handling. The material of the media when using the media-type disperser/crusher is not particularly limited, but steel, glass, alumina, zirconia, silicon nitride or the like can be used.
The classification method is not particularly limited, and examples thereof include a classification method using gravity, centrifugal force, inertial force, etc. and a classification method using a sieve. From the viewpoint of precisely controlling the classification point, when performing dry classification, a forced vortex classifier (Aerofine Classifier, manufactured by Nisshin Engineering Co., Ltd.; Micron Separator, manufactured by Hosokawa Micron Co., Ltd., Turboplex, manufactured by Hosokawa Micron Co., Ltd., etc. ) Or an inertial force field classifier utilizing the Coanda effect (Elbow Jet Mill, manufactured by Nittetsu Mining Co., Ltd.; Cliffis, manufactured by Hosokawa Micron).

In the case where the flame retardant contains ammonium polyphosphate, ammonium polyphosphate can be wet-milled and classified, but when wet-milling, while suppressing the reduction of type II ammonium polyphosphate due to excessive crushing, From the viewpoint of efficient atomization, the diameter of the medium used is preferably φ5 mm or less, more preferably φ3 mm or less, and further preferably φ1 mm or less. It is more preferable to carry out classification. As mentioned above, the ammonium polyphosphate is preferably type II, whereas the commonly available type II ammonium polyphosphate has relatively large particles present therein. When such ammonium polyphosphate is pulverized under, for example, ordinary conditions so that the particle diameter D95 falls within a predetermined range, I-type ammonium polyphosphate is generated in the II-type ammonium polyphosphate. Therefore, by wet pulverizing or classifying under the conditions as described above, ammonium polyphosphate can suitably satisfy a predetermined particle size and a peak intensity ratio in X-ray diffraction measurement within a predetermined range.

The flame retardant used in the present embodiment may contain a metal hydroxide. Thereby, flame retardancy can be further improved.
The content of the metal hydroxide is preferably 0.1 parts by mass or more, more preferably 50 parts by mass or more, and further preferably 60 parts by mass or more with respect to 100 parts by mass of the adhesive component. By setting the content to 0.1 parts by mass or more, flame retardancy can be further improved.
Incidentally, the content, from the viewpoint of improving the flame retardancy, there is no particular upper limit, but with respect to the adhesive component, if the content is excessively increased, the surface of the adhesive layer when it is used as an adhesive tape. Since the particles may be exposed and the adhesive force may be reduced, it is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 150 parts by mass or less, and particularly preferably 100 parts by mass. It is a department.

The metal hydroxide is not particularly limited, and examples thereof include magnesium hydroxide, calcium hydroxide, aluminum hydroxide, iron hydroxide, nickel hydroxide, zirconium hydroxide, titanium hydroxide, zinc hydroxide, copper hydroxide, water. Examples thereof include vanadium oxide and tin hydroxide. Among these, aluminum hydroxide is preferable because it can separate water at a relatively low temperature and thereby exhibit high flame retardancy.
In addition, 1 type(s) or 2 or more types can be used for a metal hydroxide.

Note that the metal hydroxide may be subjected to surface treatment such as coupling treatment or stearic acid treatment in order to improve dispersibility in the adhesive component. The shape of the metal hydroxide may be spherical, needle-like, flake-like or the like.

--- Aliphatic polyhydric alcohol ---
In this embodiment, the pressure-sensitive adhesive may contain an aliphatic polyhydric alcohol. Thereby, the flame retardant effect of the flame retardant can be amplified and the flame retardancy of the pressure-sensitive adhesive can be improved.
The content of the aliphatic polyhydric alcohol is preferably 5.0 parts by mass or more, more preferably 10.0 parts by mass or more, and further preferably 15.0 parts by mass or more, with respect to 100 parts by mass of the adhesive component. Is. By setting the content to 5.0 parts by mass or more, flame retardancy can be further improved.
The content has no particular upper limit from the viewpoint of improving flame retardancy. The aliphatic polyhydric alcohol improves flame retardancy by coexisting with the phosphorus-based flame retardant, but since an excessive amount may become a combustible component, 100 parts by mass relative to 100 parts by mass of the flame retardant. The amount is preferably the following, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less.

The aliphatic polyhydric alcohol is not particularly limited. Specific examples of the aliphatic polyhydric alcohol include ethylene glycol, glycerin, pentaerythritol, dipentaerythritol, tripentaerythritol, polyglycerol (triglycerol to hexaglycerol). , Ditrimethylolpropane, xylitol, sorbitol, mannitol and the like. Among these, dipentaerythritol is preferable because it has high resistance to bleeding in water and can form char efficiently with a flame retardant, especially a phosphorus flame retardant. The aliphatic polyhydric alcohol may be used alone or in combination of two or more.

---Ester of rosin compound and aliphatic polyhydric alcohol--
In the present embodiment, the pressure-sensitive adhesive can contain an ester of a rosin compound and an aliphatic polyhydric alcohol. As a result, it is possible to further impart tackiness, and it is also possible to improve the flame retardant effect of ammonium polyphosphate, and thus the flame retardancy of the pressure-sensitive adhesive.
The content of the ester of the rosin compound and the aliphatic polyhydric alcohol is preferably 0.1 part by mass or more, more preferably 10.0 parts by mass or more, with respect to 100 parts by mass of the adhesive component. It is preferably 20.0 parts by mass or more. By setting the content to 0.1 parts by mass or more, flame retardancy can be further improved.
The content has no particular upper limit from the viewpoint of improving flame retardancy, but is preferably 100 parts by mass or less, more preferably 70.0 parts by mass or less, and further preferably 50.0 parts by mass. It is as follows.

Rosin monomers, disproportionated rosins, polymerized rosins, hydrogenated rosins, and partially disproportionated rosins are mentioned as rosin-based compounds that are esters of rosin-based compounds and aliphatic polyhydric alcohols. Further, examples of the aliphatic polyhydric alcohol include the above-mentioned aliphatic polyhydric alcohols, among which diethylene glycol, glycerin, pentaerythritol and the like are preferable, and pentaerythritol is more preferable. In addition, 1 type(s) or 2 or more types can be used for a rosin type compound and an aliphatic polyhydric alcohol.

--- Other ingredients ---
In the present embodiment, the pressure-sensitive adhesive can contain a melamine derivative such as melamine cyanurate in a range that does not impair the pressure-sensitive adhesive performance, thereby further improving flame retardancy or reducing the content of the flame retardant. You can also
In addition, it is possible to improve the adhesive strength to a non-polar adherend by adding a tackifying resin in a range that does not reduce the required flame retardancy. Examples of these resins include terpene resins, terpene phenol resins, rosin resins, petroleum resins, coumarone-indene resins, and phenol resins. As the shape, a solid or viscous liquid at room temperature can be used, and the compounds may be used alone or in combination of two or more.

---Adhesive Manufacturing Method---
The pressure-sensitive adhesive is not particularly limited and can be produced, for example, by adding a predetermined flame retardant to the pressure-sensitive adhesive component, and further optionally adding the component and stirring and dispersing with a high-speed disperser.

-Manufacturing method of adhesive tape-
The pressure-sensitive adhesive tape of the present embodiment is not particularly limited and can be manufactured by a known method, for example. Specifically, in the pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer formed on one surface, the pressure-sensitive adhesive layer is formed by applying a pressure-sensitive adhesive to the surface of the release film and then drying. Then, a substrate can be attached to the surface of the pressure-sensitive adhesive layer to produce the adhesive layer. In addition, the pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer formed on both sides is obtained by applying the pressure-sensitive adhesive to the surface of the release film, followed by drying, etc., after the pressure-sensitive adhesive tape having the first pressure-sensitive adhesive layer formed on one side. It can be manufactured by forming the second pressure-sensitive adhesive layer and bonding the base material to which the first pressure-sensitive adhesive layer is bonded to the surface of the second pressure-sensitive adhesive layer.

A release film may be laminated on the pressure-sensitive adhesive tape of this embodiment to protect the pressure-sensitive adhesive layer. The release film is not particularly limited, for example, synthetic resin film such as polyethylene, polypropylene, polyester film, paper, nonwoven fabric, cloth, foamed sheet or metal foil, and at least one surface or both surfaces of a substrate such as a laminate thereof. It is possible to use those which have been subjected to a peeling treatment such as a silicone treatment for increasing the peelability from the pressure-sensitive adhesive, a long-chain alkyl treatment, or a fluorine treatment.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

First, the measurement methods and evaluation methods used in Examples and Comparative Examples will be described.
(1) Cumulative particle size distribution of flame retardant The cumulative particle size distribution of flame retardant is measured by a combination of a laser diffraction type particle size distribution measuring device (Sympatec_GmbH, HELOS) and a dry air flow type disperser (Sympatec_GmbH, RODOS/VIBRI). Was measured using.
Disperser parameters-Dispersion pressure: 3 bar, suction pressure 93 mbar, feed: 15%
Measurement parameters/density: 1.00 g/cm ³ , shape factor: 1.0

(2) Thickness of pressure-sensitive adhesive layer The obtained pressure-sensitive adhesive tape was dipped in liquid nitrogen for 1 minute and then bent and split in liquid nitrogen using tweezers to prepare a slice for observing a fractured surface. After returning the section to room temperature in a desiccator, the section was fixed on a sample stand so that an electron beam was perpendicularly incident on the fractured surface, and an electron microscope (Minscope (registered trademark) TM3030Plus manufactured by Hitachi High-Technology Corporation) was used. The fracture surface was observed. The distance from the arbitrary point on the surface of the pressure-sensitive adhesive layer (the surface in contact with the release film) in the observation visual field to the base material surface was measured at 10 points in the vertical direction, and the arithmetic average value thereof was taken as the thickness of the pressure-sensitive adhesive layer.
In the case of a double-sided tape, the thickness of the pressure-sensitive adhesive layer was determined on both sides of the tape, and the smaller value was taken as the thickness of the pressure-sensitive adhesive layer.

(3) Thickness of Adhesive Tape The thickness of the obtained adhesive tape (having a release film) was measured at 10 points randomly using a constant pressure thickness meter (Tester Sangyo Co., Ltd.). Next, the thickness of the release film was subtracted from the measured thickness, and the value obtained by arithmetically averaging was taken as the thickness of the adhesive tape.

(4) UL94 VTM Combustion Test The judgment was made by a combustion test according to the VTM test described in UL standard (UL94 “Combustion test method for plastic materials for parts of equipment”). The single-sided tape was subjected to a combustion test under both conditions with the adhesive surface outside and inside, and the lower flame retardancy judgment result was taken as the flame retardancy of the tape.

(5) 180° peel adhesion (double-sided tape)
With respect to the adhesive tape, one adhesive surface was backed with a polyester film of 25 μm to obtain a tape sample with a size of 20 mm×100 mm. A stainless steel plate was placed on the other adhesive surface of the tape sample, pressure-bonded once reciprocally using a 2 kg roller, and then left at room temperature for 1 hour. Then, it was peeled at a peeling speed of 300 mm/min in the 180° direction, and the adhesive force (N) at that time was measured.

(6) 180° peel adhesion (single-sided tape)
A stainless steel plate was placed on the adhesive surface of a tape sample having a size of 25 mm×100 mm, pressure was applied by one back and forth using a 2 kg roller, and then left at room temperature for 1 hour. Then, it was peeled at a peeling speed of 300 mm/min in the 180° direction, and the adhesive force (N) at that time was measured.

(7) X-ray Diffraction Measurement of Ammonium Polyphosphate An adhesive flame-retardant tape obtained was fixed on a glass plate with the adhesive layer facing upward, and a wide-angle X-ray diffraction chart at any three points on the surface of the adhesive layer was obtained. , X-ray diffractometer SmartLab (manufactured by Rigaku). For the chart obtained by measuring at each point, the peak intensity value at the diffraction angle 2θ = 15.5 ± 0.2° is divided by the peak intensity value at the diffraction angle 2θ = 14.6 ± 0.2°. The obtained value was obtained, and the value obtained by arithmetically averaging it was used as the X-ray diffraction peak intensity ratio.
Measurement conditions: 2θ/θ method 2θ=1 to 70 deg.
step=0.02 deg.
speed=20 deg. /Min.
Analysis software: PDXL

Subsequently, each component used in Examples and Comparative Examples will be described.
(1) Adhesive component As an adhesive component, an acrylic acid ester copolymer obtained by the following method was used.
50 parts of 2-ethylhexyl acrylate, 46 parts of n-butyl acrylate, 3.5 parts of acrylic acid, 0.5 part of 2-hydroxyethyl acrylate, and, in a reaction vessel equipped with a cooling tube, a stirrer, a thermometer, and a dropping funnel, Then, 0.2 part of 2,2′-azobisisobutyronitrile as a polymerization initiator was dissolved in 100 parts of ethyl acetate, and after nitrogen substitution, polymerization was carried out at 80° C. for 8 hours. The obtained acrylic acid ester copolymer solution had a solid content of 50% and a weight average molecular weight of 400,000.

(2) Flame retardant・(APP-1)
Ammonium polyphosphate having a D95 of 23.1 μm and a D50 of 8.8 μm (TERRAJU_C-30 manufactured by CBC) was used.

・(APP-2)
Ammonium polyphosphate (APP-1) was used with an elbow jet classifier (EJ-15, manufactured by Nittetsu Mining Co., Ltd.) at a blowing pressure of 0.5 MPa to remove coarse particles at a rate of 10% and fine particles at a rate of 0%. It is ammonium polyphosphate obtained by setting the classification edge position so as to achieve the classification treatment. D95 was 19.2 μm and D50 was 8.2 μm.

・(APP-3)
Ammonium polyphosphate (APP-1) was used with an elbow jet classifier (EJ-15, manufactured by Nittetsu Mining Co., Ltd.) at a blowing pressure of 0.5 MPa to remove coarse particles at a rate of 30% and fine particles at a rate of 0%. It is ammonium polyphosphate obtained by setting the classification edge position so as to achieve the classification treatment. D95 was 14.4 μm and D50 was 7.4 μm

・(APP-4)
Ammonium polyphosphate (APP-1) was used with an elbow jet classifier (EJ-15, manufactured by Nittetsu Mining Co., Ltd.) at a blowing pressure of 0.5 MPa to remove coarse particles at 90% and fine particles at 0%. It is ammonium polyphosphate obtained by setting the classification edge position so as to achieve the classification treatment. D95 was 7.7 μm and D50 was 3.2 μm

Melamine polylammemelam melem polyphosphate D95 was 12.3 μm and D50 was 5.0 μm, and melamine melam melem polyphosphate (PHOSMEL-200 manufactured by Hitachi Chemical Co., Ltd.) was used.

Aluminum Aluminum Hydroxide having a D95 of 7.1 μm and a D50 of 3.0 μm (BE033 manufactured by Nippon Light Metal Co., Ltd.) was used.

(3) Aliphatic Polyhydric Alcohol Dipentaerythritol (Charmer DP40 manufactured by Perstorp) was used as the aliphatic polyhydric alcohol.

(4) Tackifying resin (E-1)
Polymerized rosin pentaerythritol ester (Harita Chemical Co., Ltd., Haritac PCJ) was used.
・(E-2)
Hydrogenated rosin methyl ester (M-HDR manufactured by Maruzen Yuka Co., Ltd.) was used.

(5) Base material (S-1)
A non-woven fabric of rayon fibers having a thickness of 16 μm and 6 g/m ² (DT-6, manufactured by Papillia Nippon Paper Industries Co., Ltd.) was used.
・(S-2)
A polyimide film (Kapton 50H, manufactured by Toray-Dupont Co., Ltd.) having a thickness of 12.5 μm was used.

(6) Curing agent/epoxy cross-linking agent (Soken Chemical Co., Ltd., E-2XM, solid content 2%)

(7) Diluting solvent ethyl acetate (manufactured by Showa Denko KK) was used.

Then, the manufacturing method of an Example and a comparative example is demonstrated.
(Examples 1 to 5, Comparative Examples 1 and 2)
A flame retardant, dipentaerythritol, polymerized rosin pentaerythritol ester, hydrogenated rosin methyl ester, and epoxy cross-linking agent were added to 100 parts by mass of the solid content of the adhesive component in a composition shown in Table 1, and the mixture was thoroughly mixed until uniform. The mixture was stirred to obtain a flame-retardant adhesive.
Next, ethyl acetate was added to the obtained flame-retardant pressure-sensitive adhesive to prepare a solid content of 30%, which was then coated on a polyester release film using an applicator set to the coating thickness shown in Table 1. Then, it was heated and dried at 85° C. for 3 minutes to obtain a flame-retardant pressure-sensitive adhesive layer. The flame-retardant pressure-sensitive adhesive layer thus obtained was applied to both sides of the substrate S-1 by using a table laminator (manufactured by Tester Sangyo Co., Ltd.) at a feed rate of 2.0 m/s and a pressure of 0.25 MPa. The pieces were combined and then aged at 40° C. for 48 hours to obtain an adhesive tape having adhesive layers on both sides.
The results of evaluation of the obtained adhesive tape by the above method are shown in Table 1.
The adhesive tape of Comparative Example 1 was determined to have low adhesiveness because the base material was not attached to the first adhesive layer. Further, when a UL94VTM burning test using an adhesive tape was carried out for Comparative Example 2, all the test pieces burned due to ignition and were out of the rank of UL94VTM.

(Example 6, Comparative Example 3)
A flame retardant, dipentaerythritol, polymerized rosin pentaerythritol ester, hydrogenated rosin methyl ester, and epoxy cross-linking agent were added to 100 parts by mass of the solid content of the adhesive component in a composition shown in Table 1, and the mixture was thoroughly mixed until uniform. The mixture was stirred to obtain a flame-retardant adhesive.
Next, ethyl acetate was added to the obtained flame-retardant pressure-sensitive adhesive to prepare a solid content of 30%, and then an applicator set to have a coating thickness shown in Table 1 was used to coat the polyester release film. The composition was applied and heat-dried at 85° C. for 3 minutes to obtain a flame-retardant pressure-sensitive adhesive layer. The flame-retardant pressure-sensitive adhesive layer thus obtained was attached to one side of the substrate S-2 using a table laminator (manufactured by Tester Sangyo Co., Ltd.) at a feed rate of 2.0 m/s and a pressure of 0.25 MPa. And then 40℃ 4
By aging for 8 hours, an adhesive tape having an adhesive layer on one surface was obtained.
The results of evaluation of the obtained adhesive tape by the above method are shown in Table 1. The adhesive tape of Comparative Example 3 was determined to have low adhesiveness because the base material was not attached to the adhesive layer.

According to the present invention, it is possible to provide a pressure-sensitive adhesive tape capable of achieving a high level of both adhesiveness and flame retardancy even when the thickness is reduced.

Claims

A pressure-sensitive adhesive tape comprising a base material and a pressure-sensitive adhesive layer provided on one side or both sides of the base material,
The thickness of the adhesive tape is 30 μm or less when the adhesive layer is provided on one surface of the base material, and the thickness of the adhesive tape when the adhesive layer is provided on both surfaces of the base material. Is 50 μm or less,
The pressure-sensitive adhesive tape has a flame retardancy equal to or higher than VTM-0 in a test conforming to UL94 standard,
The pressure-sensitive adhesive layer has a thickness of 20 μm or less,
The pressure-sensitive adhesive tape, wherein the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer contains a flame retardant having a particle diameter D95 of particles corresponding to cumulative 95% from the smaller diameter side of the cumulative particle size distribution of 20.0 μm or less.
The adhesive tape according to claim 1, wherein the flame retardant includes a phosphorus-based flame retardant.
The pressure-sensitive adhesive tape according to claim 2, wherein the phosphorus-based flame retardant contains a polyphosphoric acid derivative.
The adhesive tape according to claim 2 or 3, wherein the phosphorus-based flame retardant contains ammonium polyphosphate.
The pressure-sensitive adhesive tape according to claim 4, wherein the content of ammonium polyphosphate is 65 parts by mass or more based on 100 parts by mass of the pressure-sensitive adhesive component of the pressure-sensitive adhesive.
In the X-ray diffraction measurement of ammonium polyphosphate, the peak intensity value at the diffraction angle 2θ=15.5±0.2° was divided by the peak intensity value at the diffraction angle 2θ=14.6±0.2°. The pressure-sensitive adhesive tape according to claim 4 or 5, which has a value of 1.4 or more.
The pressure-sensitive adhesive tape according to any one of claims 4 to 6, wherein the ammonium polyphosphate is classified.
The pressure-sensitive adhesive tape according to any one of claims 2 to 7, wherein the flame retardant further contains a metal hydride.