JP3498124B2 - Flame-retardant adhesive and adhesive tape using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant adhesive,
More specifically, the present invention relates to a flame-retardant pressure-sensitive adhesive having both excellent flame-retardant properties and adhesive properties and a pressure-sensitive adhesive tape using the same.

[0002]

2. Description of the Related Art Conventionally, various studies have been made and many patents have been issued on the flame retardancy of plastics used as building materials, vehicle materials, etc. It is also required that the pressure-sensitive adhesives and pressure-sensitive adhesive tapes be flame-retardant.

At present, in order to make plastics flame-retardant, a method of incorporating a flame-retardant agent into the plastics is widely adopted, but these techniques cannot be simply applied to the pressure-sensitive adhesive, and another new method is adopted. It was said that technology was needed.

The reason is that in order to make the adhesive flame-retardant,
The addition of the flame-retardant, which is a non-adhesive component, impairs the original tackiness, making it difficult to achieve both flame retardancy and tackiness. In the pressure-sensitive adhesive, it is necessary to have flame retardancy while maintaining excellent adhesive performance,
Even if the flame retardancy is improved, it is meaningless if the adhesive performance is lost.

Under these circumstances, the adhesive is
Halogen-based flame retardants are mainly used. In recent years, halogen-based flame retardants have also been used in combination with antimony, etc., and it has become possible to achieve a balance between flame retardancy and adhesive performance to some extent.

On the other hand, from the viewpoint of environmental protection and harmfulness of generated gas, regulations on the use of halogens are becoming strict, mainly in Europe, and there is an increasing demand for flame-retardant adhesives that do not use halogen-based flame retardants. .

As flame retardants other than halogen-based flame retardants in plastics, hydrated metal compounds such as aluminum hydroxide and magnesium hydroxide, and phosphoric acid esters are known.

However, when a hydrated metal compound such as aluminum hydroxide is added to the adhesive in an amount sufficient to produce a flame retardant effect, there is a problem that the adhesiveness is almost lost. On the other hand, it is necessary to add a large amount of phosphoric acid ester and the like, and as a result, there are drawbacks that the cohesive force of the pressure-sensitive adhesive is significantly reduced, and bleeding on the surface reduces the pressure-sensitive adhesive force.

[0009]

As described above, an adhesive or adhesive tape having sufficient flame retardancy and adhesiveness without using a halogen-based flame retardant has not yet been provided,
Its development was required.

[0010]

Means for Solving the Problems In view of the above-mentioned circumstances, the present inventors have conducted earnest research on flame retardancy of an adhesive, and as a result,
It has been found that it is possible to achieve both flame retardancy and adhesiveness by adding a phosphorus compound and red phosphorus, which have been conventionally known as flame retardants for plastics, to acrylic resins in a specific ratio. Completed the invention.

That is, the present invention provides the following components (a) and (a) (a) in a weight ratio of 25 to 50% by weight of a phosphorus-based compound consisting of red phosphorus and a nitrogen-containing phosphorus compound in a ratio of 1: 3 to 1:20. (A) Acrylic resin A flame-retardant pressure-sensitive adhesive containing 50 to 75% by weight is provided.

In the present invention, the phosphorus compound of the component (a) used as the flame retardant is required to have a red phosphorus and a nitrogen-containing phosphorus compound in a weight ratio of 1: 3 to 1:20.

If the weight ratio is greater than 1: 3 and if the weight ratio is less than 1:20, the flame retardancy is poor, which is not preferable.

Among the above-mentioned components (a), red phosphorus gives an excellent flame retardant effect due to a synergistic effect with a nitrogen-containing phosphorus compound, and fine particles are preferable. Further, examples of the nitrogen-containing phosphorus compound include melamine phosphate, melamine pyrophosphate, ammonium polyphosphate and the like, and one or more of these can be used.

This component (a) is contained in an acrylic resin as a pressure-sensitive adhesive base in an amount of 25 to 50% by weight (hereinafter simply referred to as "%").
)), Preferably 30-45%. If the blending amount is less than 25%, sufficient flame retardancy cannot be obtained, and 50%
If it exceeds, the adhesive strength and adhesiveness will be reduced.

On the other hand, various kinds of acrylic resin as the component (a) which is the pressure-sensitive adhesive base of the present invention can be used, and in combination with the flame retardant as the component (a), more excellent effects can be obtained. In order to (i) have 1 carbon atom as an ester group
It is preferable to use a copolymer of an acrylic acid alkyl ester monomer having an alkyl group of about 14 and a functional group-containing monomer (ii).

Among these, as the alkyl acrylate monomer of (i), methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, isoamyl acrylate, n-octyl acrylate,
Examples thereof include isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, n-decyl acrylate, and lauryl acrylate.

As the functional group-containing monomer (ii), acrylic acid, methacrylic acid, itaconic acid, (anhydrous)
Carboxy group-containing unsaturated monomers such as maleic acid, crotonic acid, β-carboxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic Examples thereof include hydroxyl group-containing unsaturated monomers such as 2-hydroxybutyl acid and bentaerythritol acrylate.

The functional group-containing monomer may be a combination of the above-mentioned carboxyl group-containing unsaturated monomer and hydroxyl group-containing unsaturated monomer, and when a hydroxyl group-containing unsaturated monomer is used, cohesive force and heat resistance are imparted. Therefore, it is preferable to carry out a crosslinking reaction with the isocyanate compound.

Examples of the isocyanate compound used for the above purpose include aromatic isocyanate compounds such as tolylene diisocyanate and kendylene diisocyanate, aliphatic isocyanate compounds such as hexamethylene diisocyanate compound, and alicyclic diisocyanate compounds such as isophorone diisocyanate. Alternatively, an adduct of a compound containing a hydroxyl group such as trimethylolpropane may be used.

The amount of the alkyl acrylate ester monomer (i) in the acrylic resin as the component (a) is 80% in the acrylic resin so that the adhesiveness is not impaired.
% To 99.5% is preferable.

On the other hand, among the functional group-containing monomers (i),
The carboxyl group-containing unsaturated monomer is 0.5 to 8.0%,
It is particularly preferably set to 1.0 to 5.0%, and the hydroxyl group-containing unsaturated monomer is 0.1 to 5.0%, and particularly 0.1 to 1.0%.
% Is preferable. If the carboxy group-containing unsaturated monomer is less than 0.5%, sufficient adhesive force cannot be obtained, and if it exceeds 8.0%, the adhesiveness after blending the flame retardant cannot be obtained. Similarly, when the content of the hydroxyl group-containing unsaturated monomer is less than 0.1%, a sufficient crosslinking effect cannot be obtained and aggregation is insufficient, and when it exceeds 5.0%, over-crosslinking occurs, and the adhesive strength and the adhesiveness are deteriorated.

Further, the isocyanate compound is 0.1 to
7%, preferably 0.3 to 3%. When the amount of the isocyanate compounded is less than 0.1%, a sufficient crosslinking effect cannot be obtained, resulting in insufficient aggregation, and when it exceeds 7.0%, over-crosslinking occurs and the adhesive strength and tackiness are reduced.

The acrylic resin of component (a), which is the adhesive base of the present invention, is preferably copolymerizable with the above-mentioned (i) alkyl acrylate monomer and (ii) functional group-containing monomer, if necessary. It can be obtained by copolymerizing an ethylenically unsaturated monomer such as vinyl acetate, methyl methacrylate, styrene and acrylonitrile.

This copolymerization can be carried out according to a known method. For example, a monomer such as (i) an alkyl acrylate monomer and (ii) a functional group-containing monomer are mixed in various organic solvents in a peroxide system. Radical polymerization may be performed using a polymerization initiator, an azo-based polymerization initiator, or the like.

The flame-retardant pressure-sensitive adhesive of the present invention can be obtained by adding the component (a) to the component (a) obtained as described above and mixing them sufficiently, It is preferable that the isocyanate compound which undergoes the crosslinking reaction is directly added to this mixture.

Further, the flame-retardant pressure-sensitive adhesive of the present invention contains a rosin-based tackifying resin such as rosin, rosin ester, hydrogenated rosin ester, polymerized rosin and polymerized rosin ester, and a terpene-based resin to the extent that the adhesiveness is not impaired. Alternatively, a terpene phenol-based tackifying resin, a petroleum-based resin or the like may be added.
By adding these components, it becomes possible to improve the adhesive force to the non-polar adherend.

In order to produce an adhesive tape using the thus obtained flame-retardant adhesive of the present invention, the flame-retardant adhesive is directly applied to a tape substrate according to a conventional method and dried. Alternatively, the flame-retardant adhesive may be applied to release paper, dried, and then transferred to a tape substrate. It is desirable that the tape base material is also a flame-retardant material. Further, the tape structure may be either a single-sided adhesive tape or a double-sided tape.

[0029]

EXAMPLES The present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples, but the present invention is not limited to these Examples.

Example 1 48 parts by weight of butyl acrylate, 48 parts by weight of 2-ethylhexyl acrylate, 4 parts by weight of acrylic acid, 0.5 parts by weight of 2-hydroxyethyl methacrylate, ethyl acetate
150 parts by weight and azobisisobutyronitrile 0.2
Charge 3 parts by weight into a three-necked flask and replace with nitrogen.
Polymerization reaction was carried out at 0 ° C. for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 630,000 in terms of GPC styrene.

45 parts by weight of ammonium polyphosphate and 15 parts by weight of red phosphorus were added to this polymer solution while stirring with a disper to obtain a dispersion solution having a solid content of 51.3%. 1.0% of an isocyanate compound (Nippon Polyurethane Co., Ltd., Coronate L solid content 75%) was added to the dispersion solution.
Parts by weight were added and mixed with sufficient stirring to obtain a pressure-sensitive adhesive. This was coated on a release paper so as to have a dry film thickness of 80 μm and dried, and transferred onto both sides of a 13 g / m ² rayon nonwoven fabric to prepare a double-sided adhesive tape.

Example 2 97 parts by weight of butyl acrylate, 3 parts by weight of acrylic acid,
2-Hydroxyethyl acrylate (0.2 parts by weight), ethyl acetate (60 parts by weight), toluene (60 parts by weight) and benzoyl peroxide (0.2 parts by weight) were charged into a three-necked flask, and the mixture was replaced with nitrogen at 80 ° C. for 8 hours. A polymerization reaction occurred.
Further, 30 parts by weight of toluene was added to prepare. The polymerization average molecular weight was 540,000.

Melamine phosphate 45 was added to this polymer solution.
Parts by weight and 10 parts by weight of red phosphorus were added while stirring with a disper to obtain a dispersion solution having a solid content of 50.3%.
Isocyanate compound (made by Nippon Polyurethane Co., Ltd.
1.5 parts by weight of Coronate L (solid content: 75%) was added and sufficiently mixed with stirring to obtain an adhesive. A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1.

Example 3 A pressure-sensitive adhesive and a pressure-sensitive adhesive tape were prepared in the same manner as in Example 2 except that the compounding amount of red phosphorus was changed to 5 parts by weight and the compounding amount of melamine phosphate was changed to 90 parts by weight.

Comparative Example 1 A pressure sensitive adhesive and a pressure sensitive adhesive tape were prepared in the same manner as in Example 2 except that the amount of red phosphorus was changed to 3 parts by weight and the amount of melamine phosphate was changed to 97 parts by weight.

Comparative Example 2 A pressure-sensitive adhesive and a pressure-sensitive adhesive tape were prepared in the same manner as in Example 2 except that the content of red phosphorus was changed to 30 parts by weight and the content of melamine phosphate was changed to 70 parts by weight.

Comparative Example 3 A pressure-sensitive adhesive and a pressure-sensitive adhesive tape were prepared in the same manner as in Example 1 except that the compounding amount of red phosphorus was changed to 25 parts by weight and the compounding amount of ammonium polyphosphate was changed to 85 parts by weight.

Comparative Example 4 A pressure-sensitive adhesive and a pressure-sensitive adhesive tape were prepared in the same manner as in Example 2 except that the content of red phosphorus was changed to 10 parts by weight and the content of melamine phosphate was changed to 35 parts by weight.

Comparative Example 5 A pressure-sensitive adhesive and a pressure-sensitive adhesive tape were prepared in the same manner as in Example 2 except that 100 parts by weight of aluminum hydroxide was added instead of red phosphorus and melamine phosphate.

Comparative Example 6 A pressure-sensitive adhesive and a pressure-sensitive adhesive tape were prepared in the same manner as in Example 2 except that 150 parts by weight of aluminum hydroxide and 100 parts by weight of antimony trioxide were added instead of red phosphorus and melamine phosphate. .

Comparative Example 7 A pressure-sensitive adhesive and a pressure-sensitive adhesive tape were prepared in the same manner as in Example 2 except that the compounding amount of red phosphorus was changed to 25 parts by weight and the compounding amount of melamine phosphate was changed to 25 parts by weight.

Test Example The performance of the pressure-sensitive adhesive and the pressure-sensitive adhesive tape prepared in Examples and Comparative Examples was examined by the following method. The results are shown in Table 1 below.

(1) Adhesion: 23 ° C., 65% RH, stainless steel plate surface-polished with No. 280 water resistant abrasive paper in an atmosphere of 65% RH, width 25 mm × length 150 m
m double-sided tape was adhered, a 25 μm polyester film was adhered from the top, and the back and forth pressure was applied once with a 2 kg roller. 20 minutes after crimping, using a tensile tester, ∠180
The peeling force was measured by pulling at a peeling angle of ° and a pulling speed of 300 mm / min.

(2) Holding power: 20m on a stainless steel plate surface-polished with No. 280 abrasive paper
Adhesive area of 20 mm x 2 with double-sided adhesive tape of mx 50 mm
It was attached so that the thickness was 0 mm, and a polyester film of 25 μm was attached from above and pressure-bonded with a 2 kg roller.
Fix it so that the sticking surface is vertical, and place it in an environment of 40 ° C for 3
After leaving for 0 minutes, a load of 1 kg was applied and the deviation after 60 minutes was measured.

(3) Ball Tack (Adhesiveness) 23 was measured by the ball tack measurement method according to the J. Dow method.
Ball tack was measured in an atmosphere of ℃ and 65% RH. (4) Flame retardance test A combustion test was performed according to the UL-94 combustion test method in the United States.

[0046] * Flame retardancy is “OK” if it does not burn (V-0) in the UL-94 combustion test method, and “NG” if it does not burn (other than V-0). And

As is clear from these results, the adhesive of the present invention had flame retardancy and excellent adhesive ability.

[0048]

EFFECT OF THE INVENTION The pressure-sensitive adhesive of the present invention and the pressure-sensitive adhesive tape using the same have excellent flame retardancy and pressure-sensitive adhesive performance, as is apparent from the above test examples. Therefore, the pressure-sensitive adhesive and pressure-sensitive adhesive tape of the present invention can be advantageously used for adhesion, fixing, coating, etc. of building materials, vehicle materials and the like. that's all

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Claims (6)

(57) [Claims] 1. The following components (a) and (a) (a) in a weight ratio of 25 to 50% by weight of a phosphorus compound consisting of red phosphorus and a nitrogen-containing phosphorus compound in a ratio of 1: 3 to 1:20, (a) ) Acrylic resin A flame-retardant pressure-sensitive adhesive containing 50 to 75% by weight. 2. The flame retardant according to claim 1, wherein the nitrogen-containing phosphorus compound as the component (a) is one or more compounds selected from melamine phosphate, melamine pyrophosphate and ammonium polyphosphate. Adhesive. 3. The acrylic resin of component (a) is a copolymer of an acrylic acid alkyl ester monomer having an alkyl group having 1 to 14 carbon atoms as an ester group and a functional group-containing monomer. Alternatively, the flame-retardant pressure-sensitive adhesive according to item 2. 4. The flame-retardant pressure-sensitive adhesive according to claim 3, wherein the functional group-containing monomer is a carboxyl group-containing unsaturated monomer or a hydroxyl group-containing unsaturated monomer. 5. The flame-retardant pressure-sensitive adhesive according to claim 3, wherein the acrylic resin as the component (a) further contains an isocyanate compound as a crosslinking agent. 6. An adhesive tape obtained by applying a flame-retardant adhesive according to any one of claims 1 to 5 to a substrate.