JP2011021103A - Flame-retardant adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant adhesive sheet which does not corrode metals, excels in transparency and fillability of unevenness, excels in adhesivity, durability and processability, and generates very little of halogen gas. <P>SOLUTION: An adhesive layer 5 constituting the flame-retardant adhesive sheet 1 includes an adhesive agent as a main component. The adhesive layer contains 10 to 30 pts.wt. in terms of solid content of a non-halogen phosphate-based flame retardant, and 0.05 to 5.0 pts.wt. in terms of solid content of a benzotriazole-based antioxidant, with respect to 100 pts.wt. of the adhesive agent. The halogen ion concentration in the adhesive layer is ≤50 ppm. The flame-retardant adhesive sheet 1 with such an adhesive layer 5 is excellent in flame retardancy, metal corrosivity, adhesivity, transparency, durability fillability of unevenness, and processability, and contains little foreign matter mingling. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flame retardant adhesive sheet. More specifically, the present invention relates to a flame retardant pressure-sensitive adhesive sheet that prevents corrosion of the metal when bonded to a metal.

  As a safety standard for materials constituting electronic devices such as displays, it is increasingly required to pass UL standards. Among them, there are many cases where a flame retardant standard is required. For example, UL94 is a flame retardant standard for electronic devices. Electronic devices may be required to have flame retardant properties that pass this standard.

  In order to impart flame retardancy to pressure-sensitive adhesive sheets, conventionally, a halogen-based flame retardant and antimony oxide have been included in the pressure-sensitive adhesive, and the pressure-sensitive adhesive has been made flame-retardant by the synergistic effect of the halogen-based flame retardant and antimony oxide. It was. However, halogen-based flame retardants generate halogen-based gases that are toxic to the human body during combustion. In addition, halogen-based flame retardants may corrode metals in electronic devices. In addition, if an adhesive contains an inorganic flame retardant such as a halogen flame retardant or antimony oxide, the color and transparency are impaired. Therefore, since the obtained pressure-sensitive adhesive layer and pressure-sensitive adhesive sheet are also colored and have a loss of transparency, there is a problem that it becomes difficult to see the image on the display when the pressure-sensitive adhesive sheet is used for a display or the like. For this reason, there is an urgent need to realize a flame retardant method that does not use a halogen-based flame retardant.

  Under such circumstances, as a method of flame retardancy without using a halogen-based flame retardant, in the field of polymer materials (plastic materials), a method of blending a hydrated metal compound such as magnesium hydroxide or aluminum hydroxide into an adhesive It has been known. Moreover, the adhesive tape using the mixture of nitrogen-containing phosphorus compounds, such as ammonium polyphosphate, and red phosphorus as a flame retardant is proposed (refer patent document 1). Moreover, the adhesive sheet which mix | blended the condensed phosphate ester type flame retardant as a flame retardant is proposed (refer patent document 2).

JP-A-8-193187 Japanese Patent Laid-Open No. 2001-271044

  However, when the method of blending a hydrated metal compound with the pressure-sensitive adhesive is used, flame retardant properties that meet the standards cannot be obtained unless a large amount of the hydrated metal compound is blended with the pressure-sensitive adhesive. Therefore, there is a problem that the adhesive properties and transparency are impaired. Moreover, since the adhesive tape of patent document 1 uses red phosphorus in order to improve a flame-retardant effect, there exists a problem that the phosphine gas which is toxic to a human body generate | occur | produces at the time of combustion. Further, in the pressure-sensitive adhesive sheet described in Patent Document 2, for example, when the pressure-sensitive adhesive sheet is bonded to the metal foil surface of an electromagnetic wave shielding film that is a functional film having a metal foil on the film surface, the phosphorus contained in the flame retardant is included. Acid ions corrode metals. For this reason, there exists a problem that the electromagnetic wave shielding function of an electromagnetic wave shielding film falls. Moreover, when such an adhesive sheet is used, there exists a problem that sufficient adhesiveness cannot be obtained with respect to the film which has an unevenness | corrugation on the surface like an electromagnetic wave shielding film.

  The present invention has been made to solve the above-described conventional problems, and does not corrode metals, has excellent transparency and unevenness embedding properties, and has excellent adhesiveness, durability, and workability. An object of the present invention is to provide a flame-retardant pressure-sensitive adhesive sheet that generates very little.

  In order to solve the above-mentioned problems, the flame-retardant pressure-sensitive adhesive sheet of the present invention uses a specific non-halogen phosphate ester flame retardant in the pressure-sensitive adhesive layer. A benzotriazole antioxidant is used in combination. The non-halogen phosphate ester flame retardant is contained in an amount of 10 to 30 parts by weight in terms of solid content with respect to 100 parts by weight of the adhesive in the adhesive layer. The benzotriazole antioxidant is contained in an amount of 0.05 to 5.0 parts by weight in terms of solid content. The adhesive layer has a halogen ion concentration of 50 ppm or less.

  The flame-retardant pressure-sensitive adhesive sheet of the present invention can provide a sufficient flame-retardant effect without using a halogen-based flame retardant or red phosphorus. Also, no halogen gas or phosphine gas is generated during combustion. Moreover, it has favorable adhesiveness. Moreover, corrosion of the metal can be prevented. Moreover, it is excellent in transparency and durability.

It is sectional drawing of the flame-retardant adhesive sheet 1. It is sectional drawing which shows the state by which the electromagnetic wave shielding film 3 was bonded by the display 7. FIG.

  In particular, the present inventors have found that there is no discoloration or peeling, and excellent durability in high temperature and high humidity conditions combined with high temperature conditions where flame retardancy is required and high humidity conditions where metal corrosion is likely to proceed. In order to obtain a flammable adhesive sheet, intensive studies were repeated.

  The structure of the flame-retardant pressure-sensitive adhesive sheet 1 will be described with reference to FIG. The flame-retardant pressure-sensitive adhesive sheet 1 includes a pressure-sensitive adhesive layer 5 containing a pressure-sensitive adhesive as a main component, and a release film 4 and a release film 6 disposed so as to sandwich the pressure-sensitive adhesive layer 5. The adhesive layer 5 contains at least a flame retardant and an antioxidant. Details of the flame retardant and the antioxidant will be described later. The flame-retardant pressure-sensitive adhesive sheet 1 is, for example, when a display 7 (see FIG. 2, described later) and a functional film (such as an electromagnetic wave shielding film 3 (see FIG. 2, described later)) are bonded. The release film 6 is peeled from the adhesive layer 5 and used. The release film 4 and the release film 6 are used for holding the adhesive layer 5. In addition, the structure which is not equipped with the release film 4 and the release film 6 may be sufficient as the flame-retardant adhesive sheet of this invention.

An example of a usage example of the flame-retardant pressure-sensitive adhesive sheet 1 will be described with reference to FIG. FIG. 2 shows a state where the pressure-sensitive adhesive layer 5 of the flame-retardant pressure-sensitive adhesive sheet 1 (see FIG. 1) is used to attach the electromagnetic wave shielding film 3 to the display 7. As shown in FIG. 2, the adhesive layer 5 penetrates well into the concave portion of the copper foil mesh 8 formed on the surface of the base film 9 (PET or the like) of the electromagnetic wave shielding film 3. For this reason, the visibility deterioration of the display 7 by bubble mixing etc. can be suppressed.
<Flame Retardant>

  Flame retardants are broadly classified into organic and inorganic types. As the inorganic flame retardant, a hydrated metal compound or the like can be used. However, inorganic flame retardants have poor compatibility with pressure-sensitive adhesives, lower transparency and tackiness, and when exposed to high-temperature and high-humidity conditions, flame retardants are likely to precipitate, further reducing transparency. This is not preferable because there is a problem in that floating and peeling progress and cause problems.

  As the organic flame retardant, phosphorus, halogen, nitrogen, and the like can be used. However, halogen-based and nitrogen-based flame retardants are preferable because they are liable to precipitate when exposed to high temperature and high humidity conditions, and further, there is a problem in that the deterioration of transparency, floating and the like progress and cause problems. Absent.

  In the present embodiment, a phosphate ester flame retardant which is a phosphorus flame retardant is used. The principle of flame retardancy of the phosphate ester flame retardant is “radical trap effect in the gas layer” and “char generation effect in the solid layer”. The “radical trapping effect in the air layer” exhibits flame retardancy by suppressing the reaction between active radicals generated by combustion and phosphoric acid and the combustion reaction continuing. The “char generation effect in the solid layer” is that phosphoric acid generated by thermal decomposition during combustion becomes polyphosphoric acid, and protonates other molecules to generate carbides by a dehydration reaction to form a surface layer. At the same time, a non-volatile phosphorous oxide is generated, and becomes a binder of the above-mentioned carbide, forms a stable surface layer, and exhibits flame retardancy by blocking heat insulation and oxygen.

  Phosphate esters are classified into non-halogen phosphate esters and halogen-containing phosphate esters. Halogenated phosphoric acid esters are not preferred because they are liable to deposit a flame retardant when exposed to high temperature and high humidity conditions, and further cause problems due to the progress of lowering of transparency and floating off.

  On the other hand, non-halogen phosphates are preferable because the flame retardant does not precipitate even when exposed to high temperature and high humidity conditions, and neither transparency deterioration nor peeling off occurs. Non-halogen phosphates include trimethyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, bisphenol A bis (diphenyl) phosphate, bisphenol A bis (dicresyl) phosphate, resorcinol bis (di-2,6- Xylenyl) phosphate, resorcinol bis (diphenyl) phosphate, and the like. Among these, bisphenol A bis (diphenyl) phosphate and resorcinol bis (di-2,6-xylenyl) phosphate are preferable, and bisphenol A bis (diphenyl) phosphate is more preferable. Using the above-mentioned substances, there is no decrease in transparency and adhesiveness, and even when exposed to high temperature and high humidity conditions, it does not easily precipitate and does not cause a decrease in adhesive strength over time, resulting in problems such as floating. It is preferable because it is difficult. In particular, durability can be improved by using bisphenol A bis (diphenyl) phosphate.

  Among non-halogen phosphates, condensed non-halogen phosphates have good compatibility with pressure-sensitive adhesives and are difficult to bleed out (exude) to the surface of the pressure-sensitive adhesive layer 5. It is preferable at the point which can prevent the adhesive force fall with time. By preventing the adhesive force from decreasing with time, the problem that the adhesive layer 5 is lifted off from the adherend can be solved.

  The non-halogen condensed phosphate ester flame retardant has a weight average molecular weight of 500 to 1200, preferably 700 to 900. When the weight average molecular weight is lower than 500, there is a possibility that a decrease in adhesive force may occur. When the molecular weight is higher than 1200, it is difficult to be compatible with the pressure-sensitive adhesive, and when exposed to high temperature and high humidity conditions, the flame retardant may be deposited, which is not preferable.

  The non-halogen phosphate-based flame retardant is blended in an amount of 10 to 30 parts by weight, preferably 20 to 28 parts by weight in terms of solid content, with respect to 100 parts by weight of the pressure-sensitive adhesive. The flame-retardant pressure-sensitive adhesive sheet 1 having excellent durability can be provided. When a large amount of non-halogen phosphate ester flame retardant is blended, the compatibility with the adhesive decreases, and when exposed to high temperature and high humidity conditions, the flame retardant precipitates or metal corrosion occurs due to the action of the phosphoric acid component. It becomes easy. For this reason, when the blending amount exceeds 30 parts by weight, the metal corrosiveness (presence / absence of corrosion of the metal surface of the adherend) and durability (when exposed to high temperature and high humidity conditions, floating due to precipitation of the flame retardant) ), Uneven embedding property (adhesive layer enters the gaps between the irregularities. If the uneven embedding property is good, it is possible to prevent bubbles from being mixed into the irregularities), workability (adhesion of the slit processing end face) There is a risk that the agent may protrude and the dropout may be reduced. In addition, there is a risk of problems such as lifting off. On the other hand, when the amount is less than 10 parts by weight, the flame retardancy effect is lowered, and the flame retardance characteristics according to the standard may not be satisfied.

  In addition, the flame retardant which consists of a non-halogen phosphate ester illustrated above may be used independently, and you may use it together with flame retardants other than a non-halogen phosphate ester. However, it is not preferable to use a halogen-based flame retardant together because the adhesiveness, transparency, durability, and unevenness embedding are reduced, and precipitation of the flame retardant is likely to occur due to a decrease in compatibility with the adhesive, resulting in foreign matter contamination. . When used in combination, it is necessary to suppress the halogen ion concentration in the adhesive layer 5 to 50 ppm or less in order to suppress a decrease in adhesiveness, transparency, durability, unevenness embedding property and contamination with foreign matter.

  Further, in the adhesive layer 5, hydrated metal compounds such as aluminum hydroxide and magnesium hydroxide, melamine resin particles, anamin resin (N-containing), antimony trioxide, silicon dioxide, etc., as long as flame retardancy is not hindered. Inorganic salts such as calcium oxide and calcium carbonate may be added. By adding these substances, the flame retardancy can be further improved.

As described above, in the present embodiment, a non-halogen phosphate ester flame retardant having a condensation type and having a weight average molecular weight of 500 to 1200, preferably 700 to 900, is added to 100 parts by weight of the adhesive. 10 to 30 parts by weight, preferably 20 to 28 parts by weight, in terms of solid content. This is preferable because a flame-retardant pressure-sensitive adhesive sheet 1 excellent in adhesiveness, metal corrosivity, unevenness embedding property and workability can be obtained. In particular, when bisphenol A bis (diphenyl) phosphate, resorcinol bis (di-2,6-xylenyl) phosphate, more preferably bisphenol A bis (diphenyl) phosphate is used, the flame-retardant pressure-sensitive adhesive sheet 1 having particularly excellent durability is provided. can do.
<Antioxidant>

  As the antioxidant, any compound that prevents the occurrence of metal rust can be used without particular limitation. For example, benzotriazole compounds, phenyltetrazole compounds, 2-aminobenzothiazole, 2-aminopyridine, 2-aminopyrimidine, 2-aminoquinoline, 2-aminoquinazoline, 4-aminoquinazoline, 2-aminoquinoxaline, 8 -Aminopurine, 2-aminobenzimidazole, aminotriazine or aminotriazole and substituted derivatives thereof. In the present embodiment, a benzotriazole-based compound is used as an antioxidant. A benzotriazole-based compound is preferable because it has high transparency and is difficult to color the pressure-sensitive adhesive, and thus can improve the transparency of the obtained flame-retardant pressure-sensitive adhesive sheet 1. Examples of the benzotriazole compounds include benzotriazole, benzotriazole sodium salt, benzotriazole potassium salt, benzotriazole amine salt, methylbenzotriazole or chlorides thereof. Furthermore, benzotriazole and methylbenzotriazole are more preferable because of their ease of handling. Among these, in order to obtain the highly transparent flame-retardant pressure-sensitive adhesive sheet 1, benzotriazole which is most difficult to color the pressure-sensitive adhesive is preferable. By using a benzotriazole-based compound, particularly benzotriazole, in the flame-retardant pressure-sensitive adhesive sheet 1 to be bonded to a film having a metal foil such as the electromagnetic wave shielding film 3, both prevention of metal corrosion and high transparency are achieved. be able to.

  The blending amount of the benzotriazole antioxidant is 0.05 to 5.0 parts by weight, preferably 0.25 to 0.50 parts by weight in terms of solid content with respect to 100 parts by weight of the adhesive in the adhesive layer 5. is there. If the amount exceeds 5.0 parts by weight, the transparency, the cohesive strength of the adhesive layer 5 and the adhesive properties may be deteriorated, which may cause problems such as peeling, insufficient fixing ability, durability, and uneven embedding. There is. If the amount is less than 0.05 parts by weight, the effect of preventing metal corrosion is reduced, and the adherend may be corroded to cause a defect.

  In the present embodiment, as described above, the non-halogen phosphate-based flame retardant is 10 to 30 parts by weight, preferably 20 to 28 parts by weight, benzotriazole antioxidant based on 100 parts by weight of the adhesive. 0.05 to 5.0 parts by weight, preferably 0.25 to 0.50 parts by weight. Moreover, halogen content, such as a halogenated flame retardant, is restrict | limited and the halogen ion concentration in the adhesion layer 5 is suppressed to 50 ppm or less. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 excellent in flame retardancy, metal corrosivity, adhesiveness, transparency, durability, unevenness embedding property, and workability can be obtained.

In addition, as the flame retardant, preferably a condensation type flame retardant can be used to further improve the adhesiveness and durability. In particular, durability can be improved by using bisphenol A bis (diphenyl) phosphate, resorcinol bis (di-2,6-xylenyl) phosphate, more preferably bisphenol A bis (diphenyl) phosphate as a flame retardant. In addition, by containing methylbenzotriazole or benzotriazole as an antioxidant, the flame-retardant pressure-sensitive adhesive sheet 1 that is most excellent in preventing metal corrosion can be obtained. More preferably, by containing benzotriazole, the flame-retardant pressure-sensitive adhesive sheet 1 having the most excellent metal corrosiveness and transparency can be obtained. By combining these, the flame-retardant pressure-sensitive adhesive sheet 1 that is most excellent in flame retardancy, metal corrosivity, adhesiveness, transparency, durability, and unevenness embedding property can be obtained.
<Adhesive>

  As the pressure-sensitive adhesive, acid-based pressure-sensitive adhesives such as ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid have been used. However, as the pressure-sensitive adhesive of the present embodiment, an acid-modified product that does not contain an acid component is used instead of the acid-based pressure-sensitive adhesive that contains an acid component that can be considered as a factor that corrodes a metal surface such as the electromagnetic wave shielding film 3. It is preferable.

  As the acid-modified product, it is particularly preferable to use an acrylic acid-modified product. Examples of acrylic acid-modified products include acrylamides such as (meth) acrylamide, N-methyl (meth) acrylamide, and N-methylol (meth) acrylamide; monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate , (Meth) acrylic acid monomethylaminopropyl, (meth) acrylic acid monoethylaminopropyl and other (meth) acrylic acid monoalkylamino esters; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid Propyl, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acryl Decyl acid, (meth) a Dodecyl acrylic acid, (meth) acrylic acid myristyl, palmityl (meth) acrylate, and stearyl (meth) acrylate.

  In addition to the acrylic acid-modified product, an acrylic acid hydroxy ester may be used in combination. Examples of the hydroxy ester of acrylic acid include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth) Examples include (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate.

  Preferably, it is preferable to use butyl acrylate and methyl acrylate in combination as an acrylic acid modified product, and further in combination with 2-hydroxyethyl acrylate, in combination with the above antioxidant and flame retardant, In addition to being excellent, metal corrosion, particularly copper corrosion, is less likely to occur, which is preferable. The ratio of butyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate is 55 to 90% by weight of butyl acrylate, 5 to 40% by weight of methyl acrylate, and 1 to 10% by weight of 2-hydroxyethyl acrylate. It is preferable that More preferably, butyl acrylate is 60 to 70% by weight, methyl acrylate is 10 to 30% by weight, and 2-hydroxyethyl acrylate is 1 to 5% by weight. This is preferable because it further improves the corrosion prevention effect against corrosion, particularly copper.

As described above, butyl acrylate as an adhesive is 55 to 90% by weight, preferably 60 to 70% by weight, methyl acrylate is 5 to 40% by weight, preferably 10 to 30% by weight, and 2-hydroxyethyl acrylate is 1 to 10% by weight, preferably 1 to 5% by weight, bisphenol A bis (diphenyl) phosphate, resorcinol having a weight average molecular weight of 500 to 1200, preferably 700 to 900, based on 100 parts by weight of the pressure-sensitive adhesive as a flame retardant Bis (di-2,6-xylenyl) phosphate, more preferably bisphenol A bis (diphenyl) phosphate is added in an amount of 10 to 30 parts by weight, preferably 20 to 28 parts by weight in terms of solid content, and benzotriazole as an antioxidant. An antioxidant, preferably benzotriazole, with respect to 100 parts by weight of the adhesive, 0.05 to 5.0 parts by weight in the form content basis, preferably formulated 0.25 to 0.50 parts by weight. Thereby, the pressure-sensitive adhesive layer 5 that prevents oxidation of the metal surface and is excellent in flame retardancy, transparency, durability, unevenness embedding property, adhesiveness, and workability can be obtained. The flame-retardant pressure-sensitive adhesive sheet 1 including the pressure-sensitive adhesive layer 5 is a particularly suitable flame-retardant pressure-sensitive adhesive sheet, for example, for a functional film having a metal foil on the film surface.
<Crosslinking agent>

  As the crosslinking agent, a general crosslinking agent can be used. For example, isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, trimethylol propane tolylene diisocyanate, diphenylmethane triisocyanate, epoxy resins such as epichlorohydrin type epoxy resin, ethylene glycol glycidyl ether, polyethylene diglycidyl ether, glycerin diglycidyl ether, etc. Compounds, amine compounds such as hexamethylenediamine, triethyldiamine, polyethyleneamine, polyvalent metals such as aluminum and metal chelate compounds, N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxide) , N, N′-toluene-2,4-bis (1-aziridinecarboxide), tri-1-aziridinylphosphine oxide, etc. Compounds. Among these, one type or a mixture of two or more types can be used. Among these, isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane tolylene diisocyanate, and diphenylmethane triisocyanate are preferable, and trimethylolpropane tolylene diisocyanate is more preferable. Good adhesiveness can be obtained by cross-linking an adhesive mainly composed of an acrylic acid-modified product or acrylic acid hydroxy ester with an isocyanate compound.

  The blending ratio of the pressure-sensitive adhesive mainly composed of acrylic acid-modified product or acrylic acid hydroxy ester and the isocyanate-based crosslinking agent is not particularly limited. For example, a functional film having irregularities on the film surface, for example, a base From the viewpoint of ensuring excellent properties in terms of uneven embedding, durability, transparency, and adhesiveness of the adhesive layer 5 with respect to the electromagnetic wave shielding film 3 having the copper foil network 8 on the surface of the material film 9, the addition amount of the crosslinking agent is adhesive. The amount is preferably from 0.10 to 15 parts by weight, more preferably from 0.5 to 5.0 parts by weight in terms of solid content, based on 100 parts by weight of the agent. When the amount is less than 0.10 parts by weight, when exposed to a high temperature and high humidity condition due to insufficient cohesive force, problems such as peeling off occur and the adhesive sticks out when the flame retardant adhesive sheet 1 is laminated. Likely to happen. In addition, since the flame-retardant pressure-sensitive adhesive sheet is soft, workability is likely to deteriorate, for example, the pressure-sensitive adhesive adheres to the blade during slitting. When the amount exceeds 15 parts by weight, a local crosslinking reaction is likely to occur, and gel foreign substances are mixed in the pressure-sensitive adhesive. For this reason, not only the unevenness embedding property is lowered but also the adhesiveness and transparency are liable to be lowered, which is not preferable.

In the flame-retardant pressure-sensitive adhesive sheet 1 of the present embodiment, 0.10 to 15 parts by weight, preferably 0.5 to 5.0 parts by weight of a crosslinking agent in terms of solid content is mixed with 100 parts by weight of the pressure-sensitive adhesive. Thus, the storage elastic modulus (G ′) at 25 ° C. of the adhesive layer is in the range of 8.1 × 10 ^{4 to} 3.9 × 10 ⁵ Pa, preferably 9.3 × 10 ^{4 to} 1.8 × 10 ⁵ Pa. It is preferable to adjust so that it becomes. By making it within the above range, the unevenness embedding property, processability, transparency, and adhesiveness are improved, and the gel-like foreign matter mixing in the adhesive caused by the local crosslinking reaction is reduced, and the surface has unevenness. In the application to be bonded to a functional film, for example, an electromagnetic wave shielding film, it is preferable because the flame-retardant pressure-sensitive adhesive sheet 1 having no transparency and excellent transparency can be provided. When the storage elastic modulus (G ′) of the pressure-sensitive adhesive layer is less than 8.1 × 10 ⁴ Pa, workability is lowered, which is not preferable. When the storage elastic modulus (G ′) of the pressure-sensitive adhesive layer exceeds 3.9 × 10 ⁵ Pa, the transparency tends to be lowered, and the embedding property of the unevenness is lowered, so that the transparency is further lowered due to the mixing of bubbles. In addition, it is not preferable because the adhesiveness is likely to be lowered.

In the present embodiment, as described above, the adhesive layer contains a non-halogen phosphate ester flame retardant and a benzotriazole antioxidant in the adhesive, and restricts the halogen content of the halogen flame retardant, etc. 5 containing a flame retardant, preferably a condensation-type flame retardant, and an antioxidant comprising methylbenzotriazole or benzotriazole, preferably benzotriazole. The flame-retardant pressure-sensitive adhesive sheet 1 is excellent in corrosiveness, adhesiveness, transparency, durability, concavo-convex embedding property and processability, and is less contaminated with foreign matter. In addition, the isocyanate-based crosslinking agent is contained in the range of 0.10 to 15 parts by weight, more preferably 0.5 to 5 parts by weight in terms of solid content, and the storage elastic modulus (G ′) is 8.1 × 10 8. ^By setting the pressure to ^{4 to} 3.9 × 10 ⁵ Pa, preferably 9.3 × 10 ^{4 to} 1.8 × 10 ⁵ Pa, the adhesiveness and the unevenness embedding property are improved, and the adhesive is applied to the film surface having the unevenness. The flame-retardant pressure-sensitive adhesive sheet 1 that is easy to enter, can prevent deterioration of transparency and appearance due to air bubbles mixed in the uneven surface, and has the most excellent metal corrosivity, adhesiveness, transparency, uneven embedding property, and workability. Since it is obtained, it is preferable.
<Tackifier>

Various tackifiers can be added within a range that does not impair the above-described effects in order to improve adhesive properties and the like. Examples of the tackifier include rosin derived from natural products and styrene derived from petroleum. However, the tackifier derived from natural products has problems such as discoloration and reduced transparency under high temperature and high humidity conditions. This is not preferable. Examples of petroleum-derived tackifiers include styrene-based and phenol-based tackifiers, and styrene-based tackifiers are particularly preferable because they are less likely to discolor under high-temperature and high-humidity conditions and easily improve tackiness. However, since the transparency tends to decrease due to blending, the blending amount is preferably 5.0 parts or less in terms of solid content.
<Other additives>

In addition, dispersants, fluorescent dyes, pH adjusters, antifoaming agents, wetting agents, preservatives, UV absorbers, surfactants, and the like can also be added. Moreover, you may contain a carbonization promoter. Carbon black etc. are mentioned as a carbonization promoter.
<Thickness of adhesive layer 5>

  10-200 micrometers is preferable and, as for the thickness of the adhesion layer obtained by apply | coating and drying the adhesive of this Embodiment to a base material, 15-100 micrometers is especially preferable. If the thickness is less than 10 μm, sufficient adhesion to the adherend is not obtained and durability is insufficient, and the embedding property to the uneven surface such as the electromagnetic wave shielding film is lowered, and bubbles are mixed and transparency is increased. May fall. If it exceeds 200 μm, transparency and workability are inferior, which is not preferable.

As described above, the storage elastic modulus (G ′) is 8.1 × 10 ^{4 to} 3.9 × 10 ⁵ Pa, preferably 9.3 × 10 ^{4 to} 1.8 × 10 ⁵ Pa, and the thickness of the adhesive layer is By setting the thickness to 10 to 200 μm, preferably 15 to 100 μm, particularly good adhesion to the uneven surface of the mesh type electromagnetic wave shielding film 3 having a thickness of the copper foil mesh 8 of 10 μm and a mesh size of 100 to several 100 μm, for example. Properties and embedding performance, transparency, and workability can be obtained.
<Release film>

The material of the release film 4 and the release film 6 on which the adhesive layer is provided is not particularly limited. For example, a plastic film such as polyester or polypropylene, a simple substance such as polyimide or polyacetal, or a composite substrate thereof, or an epoxy depending on the case. What impregnated resin etc. is mentioned.
<Electromagnetic wave shielding sheet>

  The use to which the flame-retardant pressure-sensitive adhesive sheet 1 of the present invention can be suitably used includes bonding to an electromagnetic wave shielding film.

  The electromagnetic shielding film can be roughly divided into two methods: a thin film method in which a metal film such as silver is deposited on a transparent film surface or glass surface by vapor deposition, etc., and a thin film method such as copper in a metal foil. The mesh sheet is provided thicker on the film surface or glass surface and patterned into a mesh pattern by etching, etc. to give transparency, or a mesh fiber metal such as ultrafine copper is pasted on the transparent film surface. There is a mesh method to create. In order to shield electromagnetic waves more efficiently, a mesh method is employed. In the case of the mesh method, as a typical method of providing a relatively thick metal foil such as copper on the transparent film surface, (1) a method of attaching a metal foil such as copper on the transparent film with an adhesive, etc. (2) There is a method of plating a metal such as copper by electroless plating and / or electroplating.

  In the case of (1), in order to improve the adhesion of the copper foil surface, the copper foil surface is roughened and roughened, and this is attached to a transparent film with an adhesive, and an extra copper portion is formed so as to form a mesh by etching. Remove. Since the roughened metal surface remains as it is on the solidified adhesive surface of the removed portion, the haze (cloudiness) is remarkably high and the transparency is poor. In order to improve this, the film metal surface after etching is coated with a resin, and a transparent treatment is performed to eliminate the uneven surface of the adhesive surface, but the haze is not sufficiently lowered to the level of the plating method of (2), There is a difficulty that transparency is not improved. In addition, the number of steps for the transparency treatment increases, which increases the cost of the electromagnetic wave shielding film.

  Metals such as copper provided on the mesh type electromagnetic wave shielding film may be corroded by a material used such as an adhesive that comes into contact with the metal surface, thereby impairing the function of the optical filter. In order to prevent corrosion, the metal surface patterned in a mesh pattern is treated with a triazineamine compound, a mercaptobenzimidazole compound, a thiodipropionic acid ester compound, a benzimidazole compound, or a benzotriazole compound. Alternatively, there is a method of coating the resin after immersion treatment with a solution containing thiocarbamate. Such a process requires two steps of an immersion process and a resin coating, which increases the cost.

  However, in the flame-retardant pressure-sensitive adhesive sheet 1 of the present embodiment, sufficient embedding property can be obtained even on the unevenness of the solidified adhesive surface of the removed part, so that the haze is low and the adhesive is bonded. Corrosion is also suppressed. For example, even if it is a mesh type electromagnetic wave shielding film having a copper foil thickness of 10 μm and a mesh size of 100 to several hundreds of μm, sufficient embedding property and antioxidant performance can be obtained. That is, by using the flame-retardant pressure-sensitive adhesive sheet 1 of the present embodiment, as described above, a highly transparent electromagnetic wave shielding sheet is inexpensively coated without coating the resin on the film metal surface after etching or making it transparent. Can be obtained.

As described above, butyl acrylate is 55 to 90% by weight, preferably 60 to 70% by weight, methyl acrylate is 5 to 40% by weight, preferably 10 to 30% by weight, and 2-hydroxyethyl acrylate as an adhesive. 1 to 10% by weight, preferably 1 to 5% by weight is used. As an antioxidant, a benzotriazole-based antioxidant, preferably benzotriazole, is added in an amount of 0.05 to 5.0 parts by weight, preferably 0.25 to 0.50 parts by weight in terms of solid content with respect to 100 parts by weight of the pressure-sensitive adhesive. As a non-halogen phosphate ester flame retardant, it is preferably a condensation type, and has a weight average molecular weight of 500 to 1200, preferably 700 to 900, bisphenol A bis (diphenyl) phosphate, resorcinol bis (di-2) , 6-Xylenyl) phosphate, more preferably 10-30 parts by weight, preferably 20-28 parts by weight of bisphenol A bis (diphenyl) phosphate. As a cross-linking agent, an isocyanate compound such as tolylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane tolylene diisocyanate, diphenylmethane triisocyanate, especially trimethylolpropane tolylene diisocyanate is 0 in terms of solid content with respect to 100 parts by weight of the adhesive. 10 to 15 parts by weight, preferably 0.5 to 5.0 parts by weight. The storage elastic modulus (G ′) is 8.1 × 10 ^{4 to} 3.9 × 10 ⁵ Pa, preferably 9.3 × 10 ^{4 to} 1.8 × 10 ⁵ Pa, and the adhesive coating thickness is 10 to 10 The thickness is 200 μm, preferably 15 to 100 μm. As a result, the pressure-sensitive adhesive layer 5 that prevents oxidation of the metal surface, is excellent in flame retardancy, transparency, durability, adhesiveness, unevenness embedding property, and workability, and contains less foreign matter is obtained. The flame-retardant pressure-sensitive adhesive sheet 1 provided with the pressure-sensitive adhesive layer 5 is excellent in all of the metal corrosion prevention function, flame retardance, pressure-sensitive adhesiveness and unevenness embedding property, transparency, durability, workability, and foreign matter mixing. For this reason, for example, a flame-retardant pressure-sensitive adhesive sheet particularly suitable for an uneven surface such as an electromagnetic wave shielding film, for example, a mesh type electromagnetic wave shielding film 3 having a thickness of 10 μm of a copper foil mesh 8 and a mesh size of 100 to several 100 μm. 1 can be used.

The evaluation test and results of the flame-retardant pressure-sensitive adhesive sheet 1 of the present embodiment will be specifically described below. However, the present invention is not limited to these.
<Flame retardant adhesive sheet 1 creation>

First, the detail of the created flame-retardant adhesive sheet 1 (Examples 1-22 and Comparative Examples 1-10) is demonstrated.
Example 1
Solid acrylic polymer (neutral, weight average molecular weight 1,000,000) consisting of a copolymer of butyl acrylate (65 wt%), methyl acrylate (30 wt%) and 2-hydroxyethyl acrylate (5 wt%) Non-halogen condensed phosphate ester flame retardant (bisphenol A bis (diphenyl) phosphate (trade name: FP-600, manufactured by ADEKA (weight average molecular weight 700)) (100% by weight in Table 1) : A ”) and 25 parts by weight in terms of solid content and a benzotriazole antioxidant (benzotriazole (trade name: C-Tech BT-R, manufactured by Cypro Kasei)) (in Table 1,“ substance name: H ”) To the pressure-sensitive adhesive obtained by blending 0.50 parts by weight in terms of solid content, respectively, and a polyisocyanate-based crosslinking agent (trimethylolpropane tolylene) Isocyanate) was added in an amount of 1.4 parts by weight in terms of solid content, and after stirring, the pressure-sensitive adhesive layer 5 was formed on the silicone-coated surface of the release film 4 by coating and drying so that the film thickness after drying was 25 μm. Thereafter, the silicone-coated surface of the release film 6 was bonded together to obtain a flame retardant pressure-sensitive adhesive sheet 1 (Example 1), and the release force of the release film 4 and the release film 6 was “release”. It adjusted so that it might become the relationship of "film 4> release film 6".
(Example 2)
The blending amount of the non-halogen condensed phosphate ester flame retardant blended in Example 1 was 10 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 2).
(Example 3)
The blending amount of the non-halogen condensed phosphate ester flame retardant blended in Example 1 was 20 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 3).
Example 4
The blending amount of the non-halogen condensed phosphate ester flame retardant blended in Example 1 was 28 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 4).
(Example 5)
The blending amount of the non-halogen condensed phosphate ester flame retardant blended in Example 1 was 30 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 5).
(Example 6)
The blending amount of the benzotriazole antioxidant blended in Example 1 was 0.05 part by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 6).
(Example 7)
The blending amount of the benzotriazole antioxidant blended in Example 1 was 0.25 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 7).
(Example 8)
The blending amount of the benzotriazole antioxidant blended in Example 1 was 5.00 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 8).
Example 9
The blending amount of the polyisocyanate crosslinking agent blended in Example 1 was 0.05 part by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 9).
(Example 10)
The blending amount of the polyisocyanate crosslinking agent blended in Example 1 was 0.10 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 10).
(Example 11)
The blending amount of the polyisocyanate crosslinking agent blended in Example 1 was 0.50 part by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 11).
(Example 12)
The blending amount of the polyisocyanate crosslinking agent blended in Example 1 was 5.00 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 12).
(Example 13)
The blending amount of the polyisocyanate crosslinking agent blended in Example 1 was 15.0 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 13).
(Example 14)
The blending amount of the polyisocyanate crosslinking agent blended in Example 1 was 20.0 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 14).
(Example 15)
The film thickness after drying in Example 1 was 10 μm. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 15).
(Example 16)
The film thickness after drying in Example 1 was 15 μm. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 16).
(Example 17)
The film thickness after drying in Example 1 was 100 μm. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 17).
(Example 18)
The film thickness after drying in Example 1 was 200 μm. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 18).
(Example 19)
Instead of the antioxidant compounded in Example 1, methylbenzotriazole (trade name: C-Tech TT (manufactured by Cypro Kasei)) (described as “I” in Table 2) was used. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 19).
(Example 20)
Instead of the pressure-sensitive adhesive used in Example 1, butyl acrylate (63 wt%), methyl acrylate (10 wt%), methyl methacrylate (25 wt%), acrylic acid (1.0 wt%) and acrylic An acrylic polymer (acidic) made of 2-hydroxyethyl acid (1.0% by weight) copolymer (weight average molecular weight 1 million) was used. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 20).
(Example 21)
Resorcinol bis (di-2,6-xylenyl) phosphate (trade name: PX-200 (manufactured by Daihachi Chemicals, weight average molecular weight 700)) instead of the non-halogen condensed phosphate ester flame retardant compounded in Example 1 25 parts by weight (described as “B” in Table 1) were used. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (Example 21).
(Example 22)
Instead of the non-halogen condensed phosphate ester flame retardant compounded in Example 1, a non-condensed non-halogen phosphate ester flame retardant (tris (i-propylated phenyl) phosphate (trade name: Leophos 65 (Ajinomoto Fine) Techno, weight average molecular weight 400)) (described as “C” in Table 1) was used in an amount of 25 parts by weight, and other configurations were the same as in Example 1. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 (Example) 22) was obtained.
(Comparative Example 1)
Instead of the non-halogen condensed phosphate ester flame retardant compounded in Example 1, 25 parts by weight of a brominated flame retardant (hexabromobenzene) (described as “D” in Table 1) was used. Other configurations were the same as those in Example 1. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 (Comparative Example 1) was obtained.
(Comparative Example 2)
Instead of the non-halogen condensed phosphate ester flame retardant compounded in Example 1, 25 parts by weight of a chlorine flame retardant (chlorinated paraffin) (described as “E” in Table 1) was used. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (comparative example 2).
(Comparative Example 3)
Instead of the non-halogen condensed phosphate ester flame retardant compounded in Example 1, 25 parts by weight of an inorganic flame retardant (aluminum hydroxide) (described as “F” in Table 1) was used. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (comparative example 3).
(Comparative Example 4)
In place of the non-halogen condensed phosphate ester flame retardant compounded in Example 1, 25 wt.% Of a halogen-containing phosphate ester flame retardant (tris (tribromoneopentyl) phosphate) (described as “G” in Table 1) Used. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (comparative example 4).
(Comparative Example 5)
The blending amount of the non-halogen condensed phosphate ester flame retardant blended in Example 1 was 7 parts by weight. Other configurations were the same as those in Example 1. This obtained the flame-retardant adhesive sheet 1 (comparative example 5).
(Comparative Example 6)
The blending amount of the non-halogen condensed phosphate ester flame retardant blended in Example 1 was 35 parts by weight. Other configurations were the same as those in Example 1. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 (Comparative Example 6) was obtained.
(Comparative Example 7)
Instead of the benzotriazole-based antioxidant blended in Example 1, 0.50 parts by weight of a phenol-based antioxidant (Irganox 1010: manufactured by Ciba Specialty Chemicals) (described as “J” in Table 2) was used. Other configurations were the same as those in Example 1. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 (Comparative Example 7) was obtained.
(Comparative Example 8)
Instead of the benzotriazole antioxidant compounded in Example 1, 0.50 part by weight of dibutylated hydroxytoluene (BHT) (described as “K” in Table 2) was used. Other configurations were the same as those in Example 1. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 (Comparative Example 8) was obtained.
(Comparative Example 9)
The blending amount of the benzotriazole antioxidant blended in Example 1 was 0.01 part by weight. Other configurations were the same as those in Example 1. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 (Comparative Example 9) was obtained.
(Comparative Example 10)
The blending amount of the benzotriazole antioxidant blended in Example 1 was 10.0 parts by weight. Other configurations were the same as those in Example 1. Thereby, the flame-retardant pressure-sensitive adhesive sheet 1 (Comparative Example 10) was obtained.

The details of the prepared flame-retardant pressure-sensitive adhesive sheet 1 (Examples 1 to 22) are shown in Table 1. Table 2 shows the structure of the prepared flame-retardant pressure-sensitive adhesive sheet 1 (Comparative Examples 1 to 10). Table 3 shows the halogen ion concentration and the storage elastic modulus (G ′) of the pressure-sensitive adhesive layer 5 of the flame-retardant pressure-sensitive adhesive sheet 1 produced.
<About measurement method>
(1) Thickness

The thickness of the pressure-sensitive adhesive layer 5 is determined by measuring the total thickness of the pressure-sensitive adhesive sheet 1 composed of the release film 4, the pressure-sensitive adhesive layer 5, and the release film 5 with a micrometer (manufactured by Kumagaya Kogyo Co., Ltd., product number: PRECISION MICROMETER S200-T2). The thicknesses of the release film 4 and the release film 5 were measured and subtracted.
(2) Halogen ion concentration

The pressure-sensitive adhesive layer 5 is combusted at 1,000 to 1,100 ° C. in a closed container filled with oxygen, and the combustion gas is absorbed in a weak alkaline aqueous solution and collected. The concentration of halogen ions (Cl ⁻ , Br in the collected liquid) ^{-, F -,} I ^-) ion chromatography (ICS-3000: manufactured by Dionex, column: measured with IonPac AG17-C, AS17-C ), was converted to the content level (ppm). At this time, the lower limit of detection of the halogen ion concentration (Cl ⁻ , Br ⁻ , F ⁻ , I ⁻ ) was 50 ppm.
(3) Storage elastic modulus (G ')

  The storage elastic modulus (G ′) of the pressure-sensitive adhesive layer 5 is obtained by subjecting an object under controlled temperature to periodic deformation (strain) such as pulling, bending, and twisting from the outside, and the response (stress) generated. It is measured by observing using a dynamic viscoelasticity measuring apparatus. In the present embodiment, as a method for evaluating the unevenness embedding property of the pressure-sensitive adhesive layer 5, a method is used in which the pressure-sensitive adhesive layer 5 is sandwiched between two parallel disks, the disk is rotated, and cyclic deformation is applied.

＜性能評価＞ Viscoelasticity measuring device (manufactured by Nippon Sebel Hegner Co., Ltd.) for the adhesive layer 5 alone from which both the release film 4 and the release film 6 of the flame-retardant adhesive sheet 1 (Examples 1 to 20 and Comparative Examples 1 to 10) were peeled off. , Product number: MCR301), and the storage elastic modulus (G ′) at 25 ° C. and 1 Hz was measured.

<Performance evaluation>

About the flame-retardant adhesive sheet 1 produced, (1) flame retardancy, (2) metal corrosiveness, (3) adhesiveness, (4) transparency, (5) durability, (6) unevenness embedding property, (7) Processability and (8) foreign matter contamination were evaluated. Details of the evaluation method are shown below.
(1) Flame resistance

The obtained flame-retardant pressure-sensitive adhesive sheets 1 (Examples 1 to 22 and Comparative Examples 1 to 10) were cut into a length of 150 mm and a width of 50 mm, and then the release film 6 was peeled off to form a stainless steel metal net (200 mesh). Pasted together. Next, the release film 4 was peeled off, and the exposed adhesive layer 5 was lit indirectly for 10 seconds from the vertical direction. Those that did not ignite were evaluated as “◎”, those that disappeared when the ignition source was released were evaluated as “◯”, and those that continued to burn even after the ignition source was released were evaluated as “×”.
(2) Metal corrosivity

The release film 6 of the obtained flame-retardant pressure-sensitive adhesive sheet 1 was peeled off and bonded to a base film (A4300 (manufactured by Toyobo)). It cut | disconnected to 50 mm x 50 mm, the release film 4 was peeled, and it affixed on copper foil. This sample was left in an atmosphere of 60 ° C. and 95% RH for 500 hours using a constant temperature and humidity layer (PL-3KP: manufactured by ESPEC), and the change in the copper foil was visually evaluated. A copper foil with no discoloration was evaluated as “◎”, a copper foil with a slight discoloration as “◯”, and a copper foil with a significant discoloration as “×”.
(3) Adhesiveness

The release film 6 of the obtained flame-retardant pressure-sensitive adhesive sheet 1 was peeled off and bonded to a base film (A4300 (manufactured by Toyobo)). This sample was cut into a width of 25 mm and a length of 150 mm, the release film 4 was peeled off, and then bonded to a glass plate to prepare a test piece. About this test piece, according to JIS Z0237, the substrate film was peeled off from the glass plate at a speed of 300 mm / min in the direction of 180 degrees by a load cell type tensile tester (Autograph AGS-500NG: Shimadzu Corporation) after 24 hours. The average peel strength was measured. In general, the adhesive strength used in display applications is excellent if it exceeds 10 N / 25 mm, and the adhesiveness is good if it is 5 N / 25 mm or more and less than 10 N / 25 mm, and 3 N / 25 mm or more and 5 N. If it is less than / 25 mm, the adhesiveness is low, but it can be actually used. The case where the adhesive strength was 3 N / 25 mm or more and less than 5 N / 25 mm was evaluated as “◯”, and the case where it was 5 N / 25 mm or more was evaluated as “「 ”.
(4) Transparency

The release film 6 of the obtained flame-retardant pressure-sensitive adhesive sheet 1 was peeled off and bonded to a base film (A4300 (manufactured by Toyobo)). Subsequently, the release film 4 was peeled and bonded to a glass plate having a thickness of 1 mm. In this state, the total light transmittance and the scattered light transmittance in the wavelength range of 380 nm to 780 nm were measured with an ultraviolet-visible spectrophotometer (UV-3150, manufactured by Shimadzu Corporation). The “total light transmittance” represents a ratio of light transmitted through the light incident on the flame retardant pressure-sensitive adhesive sheet 1. That is, the higher the total light transmittance is, the more light is transmitted, and thus the bright light appears. The “scattered light transmittance” represents the proportion of light that is refracted and transmitted among the light incident on the flame retardant adhesive sheet 1. The haze value is calculated by the following formula [1].
Haze value = (scattered light transmittance / total light transmittance) × 100 (%) [1]

In general, the transparency used in display applications is excellent if the total light transmittance is 90% or more and haze 1% or less, and the total light transmittance is 85% or more or haze 3% or less. If it is, the transparency is good. If the total light transmittance is less than 85% and the haze is more than 3%, the transparency is inferior. The case where the total light transmittance is 90% or more and the haze is 1% or less is “◎”, the total light transmittance is 85% or more and less than 90, or the haze is more than 1% and 3% or less. The case was evaluated as “◯”, and the case where the total light transmittance was less than 85% or the haze was more than 3% was evaluated as “x”.
(5) Durability

About the sample adjusted by the said transparency test, it was left to stand in the atmosphere of 60 degreeC95% RH for 500 hours using the constant temperature and humidity layer (PL-3KP: product made from Espec), and the change of the external appearance was evaluated visually. “◎” indicates that there is no change in appearance, such as floating, discoloration of the adhesive layer, and partial reduction in transparency due to precipitation of flame retardant, “○” indicates that there is no change in appearance and there is no problem in actual use, and “appearance” Those that could not be used because of a large change were evaluated as “x”.
(6) Embedding irregularities

The release film 6 of the obtained flame-retardant pressure-sensitive adhesive sheet 1 was peeled off and bonded to a base film (A4300 (manufactured by Toyobo)). Next, the release film 4 was peeled off, and then bonded to the surface of the electromagnetic wave shielding film 3 on which the copper foil mesh 8 was provided. Pressurization treatment (pressure treatment apparatus: autoclave (manufactured by Kurihara Seisakusho) at 50 ° C., 5 atm for 30 minutes) is performed, and the presence or absence of bubbles between the pressure-sensitive adhesive layer 5 and the electromagnetic wave shielding film 3 is visually confirmed. did. “◎” indicates that there was no bubble, “◯” indicates that there was a bubble of minute size but there was no problem in practical use, and “×” indicates that the bubble was generated and could not be used.
(7) Workability

When the obtained flame-retardant pressure-sensitive adhesive sheet 1 is slit for 100 m, “◎” indicates that there is no adhesive on the slit blade and no adhesive is missing on the slit blade, and the adhesive is attached to the slit blade. Alternatively, the case where no adhesive was missing at the slit end face portion was evaluated as “◯”, and the case where the adhesive was attached to the slit blade or the adhesive was missing at the slit end face portion was evaluated as “x”.
(8) Contamination

About the obtained flame-retardant pressure-sensitive adhesive sheet 1 (width 250 mm × length 10 m), the foreign matter mixing state due to the pressure-sensitive adhesive factor was visually confirmed. Width 250 mm × area S = 1.0 mm ² or more foreign matter to the following five / m by adhesive factors in 10m long "◎" area by adhesive factors in width 250 mm × length 10m S = 1.0 mm ² or more foreign matter to the following 10 / m "○", those area S = 1.0 mm ² or more foreign substances is more than 10 / m by adhesive factors in width 250 mm × length 10m Was evaluated as “×”.
The above evaluation results are shown in Table 4.

  As shown in Table 4, when a bromine-based (Comparative Example 1), chlorine-based (Comparative Example 2), and inorganic-based (Comparative Example 3) flame retardant is used as a flame retardant, a non-halogen phosphate ester-based flame retardant As compared with the case of using (Example 1), it was found that the adhesiveness, transparency, durability, and unevenness embedding property deteriorated (x) and foreign matter contamination increased (x). From this result, it was found that by using a non-halogen phosphate ester-based flame retardant, it is possible to produce a flame retardant pressure-sensitive adhesive sheet 1 that is excellent in adhesiveness, transparency, durability, and concavo-convex embedding properties and has little foreign matter contamination. .

  When the content of the non-halogen phosphate flame retardant is 10 parts by weight (Example 2), the metal corrosiveness, adhesiveness, transparency, durability, uneven embedding property, and workability are improved, and It was found that foreign matter mixing was reduced (◎). Further, when the content was 20 parts by weight (Example 3), the flame retardancy was improved as compared with the case where the content was 10 parts by weight (○ → ◎). On the other hand, when the content was 7 parts by weight (Comparative Example 5), the flame retardancy deteriorated compared to the case where the content was 10 parts by weight (◯ → ×). Further, when the content of the non-halogen phosphate ester flame retardant is 30 parts by weight (Example 5), flame retardancy, metal corrosiveness, adhesiveness, transparency, and unevenness embedding property are improved, and It was found that foreign matter mixing was reduced (◎). Furthermore, when the content was 28 parts by weight (Example 4), the durability and workability were improved as compared with the case where the content was 30 parts by weight (◯ → ◎). On the other hand, when the content is 35 parts by weight (Comparative Example 6), the durability is particularly deteriorated compared with the case where the content is 30 parts by weight (◯ → ×), and the metal corrosiveness and the unevenness embedding property. Worsened (◎ → ○). From this result, by setting the content of the non-halogen phosphate ester flame retardant to 10 to 30 parts by weight, particularly preferably 20 to 28 parts by weight, flame retardancy, metal corrosiveness, adhesiveness, transparency, durability It was found that the flame-retardant pressure-sensitive adhesive sheet 1 having excellent properties, unevenness embedding properties, and workability, and having less foreign matter can be produced.

  When using a phosphoric ester-based flame retardant containing halogen (Comparative Example 4), compared to using a non-halogen phosphoric ester-based flame retardant (Example 1), tackiness, transparency, durability, Further, it was found that the unevenness embedding property was deteriorated (×), and foreign matter contamination was increased (×). From this result, it can be seen that by using a non-halogen phosphate ester flame retardant, it is possible to produce a flame retardant pressure-sensitive adhesive sheet 1 that is excellent in adhesiveness, transparency, durability, and unevenness embedding properties, and is less contaminated with foreign matter. It was.

  In the case of using a condensed non-halogen phosphate flame retardant (Example 1), compared to the case of using a non-condensed non-halogen phosphate ester flame retardant (Example 22), the adhesiveness and It was found that the durability was improved (○ → ◎). From this result, it was found that by using a condensation type non-halogen phosphate ester flame retardant, it is possible to produce a flame retardant pressure-sensitive adhesive sheet 1 having better adhesiveness and durability.

  When bisphenol A bis (diphenyl) phosphate is used as a non-halogen condensed phosphate ester flame retardant (Example 1), or when resorcinol bis (di-2,6-xylenyl) phosphate is used (Example 21) In addition, good flame retardancy (◎) was exhibited. Further, when bisphenol A bis (diphenyl) phosphate was used, durability was improved as compared with the case where resorcinol bis (di-2,6-xylenyl) phosphate was used (（→→). Therefore, bisphenol A bis (diphenyl) phosphate and resorcinol bis (di-2,6-xylenyl) phosphate can be used as the non-halogen condensed phosphate ester flame retardant, and in particular, bisphenol A bis (diphenyl) phosphate is used. It turned out to be more preferable.

  As the antioxidant, a phenolic antioxidant (Comparative Example 7) and a dibutylated hydroxytoluene (Comparative Example 8) were used, compared with a case where a benzotriazole antioxidant was used (Example 1). The metal corrosivity deteriorated (×). From this result, it turned out that the flame-retardant adhesive sheet 1 excellent in metal corrosivity can be produced by using a benzotriazole antioxidant. Further, when benzotriazole was used as a benzotriazole-based antioxidant (Example 1) or when methylbenzotriazole was used (Example 19), good metal corrosivity (（) was exhibited. Furthermore, transparency was improved when benzotriazole was used compared to when methylbenzotriazole was used (○ → ◎). This indicates that benzotriazole or methylbenzotriazole can be used as the benzotriazole antioxidant, and benzotriazole is particularly preferable.

  When the content of the benzotriazole-based antioxidant is 0.05 parts by weight (Example 6), flame retardancy, adhesiveness, transparency, durability, uneven embedding property, and workability are improved (◎ ), And it was found that there was less foreign matter contamination (（). Furthermore, when the content was 0.25 parts by weight (Example 7), the metal corrosiveness was improved as compared to 0.05 parts by weight (◯ → ◎). On the other hand, when the content was 0.01 parts by weight (Comparative Example 9), the metal corrosivity was deteriorated as compared with the case where the content was 0.05 parts by weight (◯ → ×). In addition, when the content of the benzotriazole antioxidant is 5.0 parts by weight (Example 8), flame retardancy, metal corrosiveness, adhesiveness, transparency, uneven embedding property, and workability are good. And (◎), and it was found that foreign matter contamination was reduced (◎). Furthermore, when the content was 0.5 parts by weight (Example 1), the durability was improved as compared with the case where the content was 5.0 parts by weight (◯ → ◎). On the other hand, when the content is 10.0 parts by weight (Comparative Example 10), compared with the case where the content is 5.0 parts by weight, the transparency and the uneven step embedding are particularly deteriorated ( ◎ → ×), durability deteriorated (○ → ×). From this result, by setting the content of the benzotriazole antioxidant to 0.05 to 50 parts by weight, particularly preferably 0.25 to 0.5 parts by weight, flame retardancy, metal corrosiveness, adhesiveness, It was found that the flame-retardant pressure-sensitive adhesive sheet 1 having excellent transparency, durability, concavo-convex embedding property, and processability and having less foreign matter can be produced.

  When the content of the cross-linking agent is 0.10 parts by weight (Example 10), it is excellent in flame retardancy, metal corrosiveness, adhesiveness, transparency, durability, and unevenness embedding (◎) and contains foreign matter. Was found to be reduced (◎). Further, when the content was 0.50 parts by weight (Example 11), the workability was improved (◯ → ◎) compared to the case where the content was 0.10 parts by weight. On the other hand, when the content was set to 0.05 parts by weight (Example 9), the durability deteriorated compared to the case where the content was set to 0.10 parts by weight (◎ → ○). Further, it was found that when the content of the crosslinking agent was 15.0 parts by weight (Example 13), the flame retardancy, metal corrosivity, durability, and workability were excellent (（). Furthermore, when the content was 5.00 parts by weight (Example 12), compared with the case where the content was 15 parts by weight, the adhesiveness, transparency, and unevenness embedding properties were improved (○ → ◎). , Foreign matter contamination was reduced (○ → ◎). On the other hand, when the content was 20.0 parts by weight (Example 14), the haze value was deteriorated as compared with the case where the content was 15.0 parts by weight (1.2 → 1.6). From this result, by setting the content of the crosslinking agent to 0.10 to 15.0 parts, particularly preferably 0.50 parts to 5.00 parts, flame retardancy, metal corrosiveness, adhesiveness, transparency, It was found that the flame-retardant pressure-sensitive adhesive sheet 1 having excellent durability, concavo-convex embedding properties, and processability and having less foreign matter can be produced.

  It was found that when an acid-based pressure-sensitive adhesive (Example 20) was used as the pressure-sensitive adhesive instead of the acid-modified product containing no acid component (Example 1), the metal corrosivity deteriorated (（→ ◯). From this result, it was found that by using an acid-modified product as the pressure-sensitive adhesive, the flame-retardant pressure-sensitive adhesive sheet 1 having excellent metal corrosivity can be produced.

  When the thickness of the adhesive layer 5 is 10 μm (Example 15), it is excellent in flame retardancy, metal corrosiveness, adhesiveness, transparency, and workability (◎), and foreign matter contamination is reduced (◎). all right. Furthermore, when the thickness was 15 μm (Example 16), the durability and the unevenness embedding property were improved (◯ → ◎). Further, when the thickness of the adhesive layer 5 is 200 μm (Example 18), the flame retardancy, the metal corrosiveness, the adhesiveness, the durability, and the unevenness embedding property are excellent (◎), and foreign matter mixing is reduced (◎). )I understood it. Furthermore, when the thickness was 100 μm (Example 17), the transparency and workability were improved (◯ → ◎). From this result, by setting the thickness of the pressure-sensitive adhesive layer 5 to 10 to 200 μm, particularly preferably 15 to 100 μm, flame retardancy, metal corrosiveness, adhesiveness, transparency, durability, unevenness embedding property, and workability can be achieved. It was found that the flame-retardant pressure-sensitive adhesive sheet 1 which is excellent and has few foreign matters can be produced.

  As shown in Table 3, in Examples 1 to 22 using a non-halogen flame retardant, the halogen ion concentration was 50 ppm or less. On the other hand, when using a brominated flame retardant (Comparative Example 1), using a chlorine based flame retardant (Comparative Example 2), and using a halogen-containing flame retardant (Comparative Example 4), The halogen ion concentration became very large (Comparative Example 1: 450,000, Comparative Example 2: 210000, Comparative Example 4: 360000). From this result, it was found that the halogen ion concentration can be suppressed to 50 ppm or less by using a flame retardant containing no halogen.

As shown in Table 3, in Examples 1 to 22, the storage elastic modulus (G ′) is in the range of 8.10 × 10 ⁴ (Example 10) to 3.90 × 10 ⁵ Pa (Example 13). Value. Further, when the storage elastic modulus (G ′) is 9.34 × 10 ⁴ (Example 11) to 1.81 × 10 ⁵ Pa (Example 12), flame retardancy, metal corrosivity, adhesiveness, It turned out that it becomes the flame-retardant adhesive sheet 1 which is excellent in all of transparency, durability, unevenness embedding property, and workability, and has few foreign matter mixing.

1 Flame-retardant adhesive sheet 5 Adhesive layer

Claims (4)

  A flame-retardant pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer mainly composed of a pressure-sensitive adhesive, wherein the pressure-sensitive adhesive layer is 10 to 10 parts by weight of non-halogen phosphate-based flame retardant in terms of solid content with respect to 100 parts by weight of the pressure-sensitive adhesive. Flame retardancy characterized by containing 30 parts by weight and containing 0.05 to 5.0 parts by weight of a benzotriazole antioxidant in terms of solid content, and the halogen ion concentration of the adhesive layer is 50 ppm or less Adhesive sheet.   The flame retardant pressure-sensitive adhesive sheet according to claim 1, wherein the non-halogen phosphate ester flame retardant is a non-halogen condensed phosphate ester flame retardant.   The flame-retardant pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the benzotriazole-based antioxidant is benzotriazole or methylbenzotriazole. The adhesive is contained in an amount of 0.1 to 15 parts by weight in terms of solid content with respect to 100 parts by weight of the adhesive, and the storage elastic modulus at 25 ° C. of the adhesive layer is 8.1 × 10 ^{4 to} 3.9 × 10 ^5. The flame-retardant pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer is Pa and the coating thickness of the pressure-sensitive adhesive layer is 10 to 200 μm.

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