JPH11189753A - Flame-retardant adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant adhesive tape not generating a poisonous halogen gas on combustion and not containing antimony affecting human bodies. SOLUTION: This flame-retardant adhesive tape is obtained by disposing the first adhesive layer containing ammonium polyphosphate on at least one surface of a substrate. Therein, the maximum particle diameter of the ammonium polyphosphate is <=300% of the thickness of the adhesive layer, and the specific surface area of the ammonium polyphosphate is >=7500 cm<2> /cm<3> . At least one of the second adhesive agent layer not containing the ammonium polyphosphate is disposed on the adhesive agent layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant pressure-sensitive adhesive tape, which does not generate a toxic halogen-based gas upon burning and does not contain antimony which has an adverse effect on the human body. Electronic components.

[0002]

2. Description of the Related Art For example, electronic components and materials constituting them are required to pass UL standards as a safety standard. Often required. For example,
UL 510 is a UL standard for electrical insulating tapes used for electronic components and the like, and high flame retardant properties that meet this standard are required. The same applies to other flame retardant standards.

In order to impart flame retardancy to this pressure-sensitive adhesive tape, it has been common practice to use a halogen-based flame retardant and antimony oxide in combination to make the adhesive tape flame-retardant. Flame retardants may generate toxic halogen-based gases when burned, and may cause corrosion of equipment, etc.Therefore, there is an urgent need to investigate flame retardant methods that do not use halogen-based flame retardants. I have.

[0004]

As a flame retarding method using no halogen-based flame retardant, a hydrated metal compound such as magnesium hydroxide or aluminum hydroxide is compounded in the field of other polymer materials (plastic materials). However, in order to obtain the flame-retardant effect expected of the pressure-sensitive adhesive tape, a large amount must be blended with the base polymer, which causes a problem that the pressure-sensitive adhesive properties are impaired. Further, an adhesive tape using a mixture of a nitrogen-containing phosphorus compound such as ammonium polyphosphate and red phosphorus as a flame retardant has been proposed (JP-A-8-193187).
However, there is a problem that phosphine gas is generated because red phosphorus is used to improve the flame retardant effect. In order to solve such a problem, the present inventors have proposed an adhesive tape in which a specific ammonium polyphosphate is blended in an adhesive layer (Japanese Patent Application No. 9-158496). Has an effect on the decrease of the adhesive property, and presently causes a problem when winding a tape by an automatic winding device or a manual operation which is practically used in the production of transformers and the like today. There was a risk of line trouble.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the use of ammonium polyphosphate having a specific particle size and a specific surface area in an adhesive layer makes it possible to obtain red phosphorus or the like. It is possible to obtain a pressure-sensitive adhesive tape that does not generate a halogen gas or a phosphine gas, and that a sufficient flame-retardant effect can be obtained even without using an adhesive gas, and further by providing a normal pressure-sensitive adhesive layer on the pressure-sensitive adhesive layer. The present inventors have found that a pressure-sensitive adhesive tape having excellent pressure-sensitive adhesive properties without lowering the pressure-sensitive adhesive properties can be obtained, which has led to the present invention.

That is, according to the present invention, at least one side of
A flame-retardant pressure-sensitive adhesive tape provided with a first pressure-sensitive adhesive layer containing ammonium polyphosphate, wherein the maximum particle size of the ammonium polyphosphate is 300% or less of the thickness of the pressure-sensitive adhesive layer, and the specific surface area is The present invention relates to a flame-retardant pressure-sensitive adhesive tape characterized in that the pressure-sensitive adhesive layer has a thickness of at least 7,500 cm2 / cm3 and further has at least one second pressure-sensitive adhesive layer not containing ammonium polyphosphate on the pressure-sensitive adhesive layer. .

[0007]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the maximum particle size of the ammonium polyphosphate contained in the pressure-sensitive adhesive layer must be 300% or less of the thickness of the pressure-sensitive adhesive layer, preferably 200% or less. , More preferably 10 to 100%
A degree is desirable. The specific maximum particle size depends on the thickness of the pressure-sensitive adhesive layer, but is preferably 100 μm or less, and more preferably about 5 to 30 μm. If this maximum particle size exceeds 300% of the thickness of the pressure-sensitive adhesive layer, the smoothness of the surface of the pressure-sensitive adhesive layer after application of the pressure-sensitive adhesive is lost, so that the contact area with the adherend cannot be obtained, which leads to a decrease in the pressure-sensitive adhesive properties. Problem. Here, the maximum particle size is the% particle size 9 measured by a laser diffraction / scattering type particle size distribution analyzer (LA-91B) manufactured by HORIBA.
The value of 9.9 was taken as the maximum particle size.

Further, in the present invention, the specific surface area of ammonium polyphosphate needs to be 7500 cm2 / cm3 or more, and preferably about 8000 to 9000 cm2 / cm3. If the specific surface area is less than 7,500 cm2 / cm3, the standard level required for flame retardancy will not be attained. Here, the specific surface area means the total sum of the particle surface areas per unit volume measured by the same apparatus as the above-mentioned maximum particle diameter.

The ammonium polyphosphate is used in an amount of usually 10 to 100 parts by weight, preferably 2 to 100 parts by weight, for example, based on 100 parts by weight of a base polymer such as an acrylic or rubber-based resin.
0 to 50 parts by weight are blended. If the blending amount of ammonium polyphosphate is too large, the cohesiveness of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive property may be reduced, causing problems such as sticking, peeling, and insufficient fixing ability. On the other hand, if the amount is too small, the effect of the flame retardancy is reduced, and the flame retardant characteristics in the standard may not be satisfied.

The acrylic resin and rubber resin used here are not particularly limited. For example, the acrylic resin may be a mixture of an alkyl acrylate monomer such as butyl acrylate and a functional group-containing monomer such as acrylic acid. Examples of the rubber-based resin include natural rubber, polyisobutylene, isoprene rubber, and a hot-melt adhesive such as SBR and SEBS. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is usually 10 to 100 μm, preferably 20 to 50 μm.

[0011] Flame retardancy is further improved by adding a small amount of a hydrated metal compound such as magnesium hydroxide or aluminum hydroxide to the first pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention, if necessary. It can also be done. Also,
Various tackifiers such as a rosin-based resin may be added to improve the adhesive properties, as long as the flame retardant properties are not impaired. Further, if necessary, a crosslinking agent such as a polyisocyanate may be mixed to improve the cohesive strength and heat resistance.

The substrate on which the first pressure-sensitive adhesive layer is provided is
There is no particular limitation, for example, a plastic film such as polyester, polypropylene, paper, non-woven fabric, etc., a heat-resistant polyimide, polyamide, a simple substance such as polyacetate or a composite base material thereof, and optionally impregnated with an epoxy resin or the like. And the like. The pressure-sensitive adhesive layer can be provided on at least one side of this substrate, that is, on one side or both sides, by applying a single layer or multiple layers, respectively. In addition, it is preferable that such a base material also has flame retardancy.

In the present invention, at least one second pressure-sensitive adhesive layer not containing ammonium polyphosphate is provided on the first flame-retardant pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer is not particularly limited as long as it does not contain ammonium polyphosphate. For example, the same pressure-sensitive adhesive as the above-mentioned pressure-sensitive adhesive layer can be used. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is usually 0.08 to 10 μm, preferably 0.1 to 5 μm.

The flame retardant pressure-sensitive adhesive tape of the present invention has an oxygen index of 21 or more, preferably 25, as an index of its flame retardancy.
It is desirable that it is above. If the oxygen index is less than 21, the fuel may become flammable and the self-extinguishing property may be lost.

The flame-retardant pressure-sensitive adhesive tape of the present invention does not contain a halogen-based flame retardant and has a halogen ion concentration of 10 ppm.
Below, preferably 5 ppm or less is desirable. If the halogen ion concentration is too high, the applied tape may be corroded depending on the place or conditions where the pressure-sensitive adhesive tape of the present invention is used, especially when used for electronic parts and the like. Attention is required.

The flame-retardant pressure-sensitive adhesive tape of the present invention is not particularly limited as long as its use is required to be flame-retardant, but it is suitably used particularly for various electronic components which are easily affected by halogen gas. To form electronic components. Such electronic components are not particularly limited, and include, for example, transformer interlayer insulation and exterior insulation.

[0017]

As described above, the flame-retardant pressure-sensitive adhesive tape of the present invention has both good flame-retardant properties and adhesive properties, and further has the effect of not generating toxic gases such as halogen gas and phosphine gas. .

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Hereinafter, “parts” means “parts by weight”. Example 1 Solid content 1 of an acrylic polymer composed of a copolymer of butyl acrylate and acrylic acid (weight average molecular weight: about 600,000)
An ammonium polyphosphate flame retardant having a maximum particle size of 30 μm and a specific surface area of 8000 cm 2 / cm 3 (trade name: Terage C60, manufactured by Chisso Corporation) was added to 4 parts by weight.
0 parts by weight, further added 3 parts by weight of a polyisocyanate-based crosslinking agent, and stirred and mixed. The resulting adhesive was dried on one side of a polyester film (25 μm thick) so that the thickness after drying was 25 μm. Applied. Next, on the pressure-sensitive adhesive layer, a solid content of the same acrylic polymer 1
To 100 parts by weight, 3 parts by weight of a polyisocyanate-based cross-linking agent was added, and the resulting pressure-sensitive adhesive was transferred and coated so that the thickness after drying was 5 μm. An adhesive tape was obtained.

Example 2 Solid content 1 of an acrylic polymer composed of a copolymer of butyl acrylate and acrylic acid (weight average molecular weight: about 600,000)
An ammonium polyphosphate flame retardant having a maximum particle size of 30 μm and a specific surface area of 8000 cm 2 / cm 3 (trade name: Terage C60, manufactured by Chisso Corporation) was added to 3 parts by weight.
0 parts by weight, 15 parts by weight of aluminum hydroxide, 3 parts by weight of a polyisocyanate-based cross-linking agent were added, and the mixture was stirred and mixed.
(5 μm thick) so that the thickness after drying was 25 μm. Next, on the pressure-sensitive adhesive layer, based on 100 parts by weight of the same acrylic polymer solid content as above,
A pressure-sensitive adhesive obtained by adding 3 parts by weight of a polyisocyanate-based cross-linking agent and stirring and mixing was transferred and coated so that the thickness after drying was 0.1 μm to obtain a flame-retardant pressure-sensitive adhesive tape of the present invention. .

Example 3 Solid content 1 of an acrylic polymer composed of a copolymer of butyl acrylate and acrylic acid (weight average molecular weight: about 600,000)
5 parts by weight of an ammonium polyphosphate flame retardant having a maximum particle size of 30 μm and a specific surface area of 8000 cm 2 / cm 3 (trade name: Terage C60, manufactured by Chisso Corporation)
0 parts by weight, 10 parts by weight of a rosin-based resin (trade name: Superester A-125, manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifier, 3 parts by weight of a polyisocyanate-based cross-linking agent were further added, followed by stirring and mixing. The obtained pressure-sensitive adhesive was applied on one side of a polyester film (25 μm thick) to a thickness of 25 μm after drying.
m. Next, on the pressure-sensitive adhesive layer, 3 parts by weight of a polyisocyanate-based crosslinking agent with respect to 100 parts by weight of a solid content of the same acrylic polymer as described above,
In addition, rosin resin (trade name: Super Ester A-12)
5, Arakawa Chemical Industry Co., Ltd.), 10 parts by weight, and the resulting mixture was stirred and mixed.
m to obtain a flame-retardant pressure-sensitive adhesive tape of the present invention.

Comparative Example 1 Solid content 1 of an acrylic polymer composed of a copolymer of butyl acrylate and acrylic acid (weight average molecular weight: about 600,000)
An ammonium polyphosphate flame retardant having a maximum particle size of 30 μm and a specific surface area of 8000 cm 2 / cm 3 (trade name: Terage C60, manufactured by Chisso Corporation) was added to 4 parts by weight.
0 parts by weight, further added 3 parts by weight of a polyisocyanate-based crosslinking agent, and stirred and mixed. The resulting adhesive was dried on one side of a polyester film (25 μm thick) so that the thickness after drying was 25 μm. By coating, a flame-retardant adhesive tape was obtained.

Various properties of the obtained flame-retardant pressure-sensitive adhesive tape were measured by the following methods, and the results are shown in Table 1. From these results, it can be seen that the flame-retardant pressure-sensitive adhesive tape of the present invention has a good balance of flame retardancy and pressure-sensitive adhesive properties as a pressure-sensitive adhesive tape without using a halogen-based flame retardant or antimony oxide.

[Adhesive strength] A stainless steel plate was used as the adherend, and the tape was reciprocated once with a roller having a load of 2 kg, and the adhesive tape was bonded.
/ min.

[Flame Retardancy Test] A combustion test was performed according to the UL standard (UL510) to make a judgment.

[Dielectric Breakdown Voltage] The voltage at the time of dielectric breakdown was measured according to JIS C 2107.

[Corrosion test] According to JIS K2513,
Judgment was made according to the following criteria based on the discoloration number from the copper plate corrosion standard. ：: 1-3 ×: 4

[Halogen gas generation] Around 20 mg of a sample was weighed and burned in a combustion flask. At this time, the generated gas was absorbed in 25 ml of an absorbing solution and analyzed by ion chromatography to check the generation of halogen gas. Was. At this time, 1
Those exceeding 000 ppm were determined to generate halogen gas.

[Oxygen index] Measured according to JIS K7201.

[Halogen ion concentration (pure water boiling extraction method)] Pretreatment The adhesive tapes obtained in Examples and Comparative Examples were each
The sample was cut out into a size of cm 2 and used as a measurement sample. 50 ml of pure water (ion-exchanged water having a conductivity of 1 μS or less)
Together with a lidded polypropylene container (washed thoroughly with pure water), and after closing the lid, the container was immersed in boiled pure water and subjected to an extraction treatment in a boiling water bath for 30 minutes.・ Measurement The halide ions (Cl-, B
The concentration of r-, F-, I-) was determined using ion chromatography. Apparatus: DX-AQ1110 (DIONEX) Eluent: 2.7 mM-Na2CO3, 0.3 mM-Na
HCO3 separation column: AS12 Guard column: AG12

[Probe tack test] JIS Z 023
7 was measured.

[0031]

[Table 1]

Claims (7)

[Claims] 1. A flame-retardant pressure-sensitive adhesive tape comprising a substrate and a first pressure-sensitive adhesive layer containing ammonium polyphosphate provided on at least one surface of the substrate, wherein the maximum particle size of the ammonium polyphosphate is the pressure-sensitive adhesive layer. And a specific surface area of 7500 cm2 / cm3 or more, and at least one second adhesive layer not containing ammonium polyphosphate is provided on the adhesive layer. Flame retardant adhesive tape. 2. The maximum particle size of ammonium polyphosphate is as follows:
The flame-retardant pressure-sensitive adhesive tape according to claim 1, wherein the thickness is 100 µm or less. 3. The method according to claim 1, wherein the first pressure-sensitive adhesive layer contains 10 to 100 parts by weight of ammonium polyphosphate based on 100 parts by weight of the acrylic resin or the rubber-based resin. Flame retardant adhesive tape. 4. The flame-retardant pressure-sensitive adhesive tape according to claim 1, wherein the oxygen index is 21 or more. 5. The flame-retardant pressure-sensitive adhesive tape according to claim 1, which does not contain a halogen-based flame retardant and has a halogen ion concentration of 10 ppm or less. 6. A flame-retardant pressure-sensitive adhesive tape for electronic components, wherein the flame-retardant pressure-sensitive adhesive tape according to claim 1 is used for bonding and fixing electronic components. 7. Electronic parts obtained by bonding the flame-retardant pressure-sensitive adhesive tape according to claim 1 to electronic parts.