JPH05320604A - Pressure-sensitive acrylic adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the subject compsn. which adheres firmly to a lowly polar adhered such as an olefin resin and is excellent in heat resistance. CONSTITUTION:100 pts.wt. acrylic resin obtd. from 80-100wt.% at least one monomer represented by the general formula: CH2=CR<1>-COOR<2> (wherein R<1> is H or CH3; and R<2> is 2-18C alkyl) and 0-20wt.% monomer copolymerizable therewith is compounded with 1-40 pts.wt. tackifying resin which comprises 97.5-25wt.% low-melting resin having a softening point of 80-140 deg.C and 2.5-75wt.% high-melting resin having a softening point of 140-200 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition having high adhesiveness to an adherend having low polarity such as olefin resin and having excellent heat resistance.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a means for improving the adhesiveness of an acrylic pressure-sensitive adhesive to a low-polarity adherend such as an olefin resin, a monomer forming a polymer having a low glass transition temperature (Tg) is used, or the amount of a cross-linking agent used for an adhesive is adjusted. Measures such as reducing the number are taken. However, when such a method is used, the adhesiveness to an adherend having a low polarity such as an olefin resin is improved, but on the other hand, there is a problem that the heat resistance is significantly reduced.

An object of the present invention is to solve such conventional problems and provide a pressure-sensitive adhesive composition having high adhesiveness to an adherend having low polarity such as an olefin resin and having excellent heat resistance. Especially.

[0004]

The acrylic pressure-sensitive adhesive composition of the present invention has the following general formula: CH ₂ = CR ¹ -COOR ² (wherein R ¹ is H or CH ₃ and R ² is carbon). Number 2-18
Which represents an alkyl group of
It contains an acrylic copolymer (A) and a tackifying resin (B) having 0 to 100% by weight and 0 to 20% by weight of another monomer copolymerizable with these monomers as a copolymerization component. An acrylic pressure-sensitive adhesive composition, wherein the tackifying resin (B) has a low softening point resin (Ba) having a softening point of 80 ° C or higher and lower than 140 ° C and a high softening point of 140 ° C or higher and lower than 200 ° C. It is a combination of resins (B-b) and the addition number of the tackifying resin (B) is the acrylic copolymer (A) 10
It is characterized in that it is 1 to 40 parts by weight with respect to 0 parts by weight.

In the present invention, the tackifying resin (B)
Is a low softening point resin (Ba) and a high softening point resin (Bb)
And a high softening point resin (B-
The compounding ratio of the resin b) is 2.5% by weight or more and 75% by weight or less as a compounding ratio x shown below.

[0006]

[Equation 1]

Examples of the low softening point resin (Ba) used in the present invention include disproportionated rosin ester resins and hydrogenated rosin ester resins. Examples of the high softening point resin (Bb) include rosin-modified phenol resin, coumarone-indene resin, polymerized rosin resin, and xylene resin.

The monomer component constituting the acrylic copolymer (A) used in the present invention is one or more kinds of (meth) acrylic acid ester monomer (a) represented by the above general formula, and this monomer. It is another monomer (b) that can be copolymerized. As the monomer (a), acrylic acid n
-Butyl ester, acrylic acid 2-ethylhexyl ester, acrylic acid isooctyl ester, acrylic acid nonyl ester, and other monomers capable of forming an adhesive polymer are preferably used, and (meth) acrylic acid ethyl ester and other monomers are also glass. It is used as necessary such as adjusting the transition temperature (Tg).

The monomer (b) is preferably a monomer capable of reacting with a cross-linking agent to form a polymer capable of improving cohesive force, such as (meth) acrylic acid, (meth) acrylic acid 2-hydroxyethyl ester and acrylamide. Used, (meth) acrylic acid methyl ester, vinyl acetate,
It is also possible to use a monomer capable of forming a polymer having a high Tg such as styrene or N-vinylpyrrolidone. The copolymer composed of the monomers (a) and (b) is prepared by solution polymerization or bulk polymerization using a polymerization initiator such as benzoyl peroxide or azobisisobutyronitrile.
Further, it can be produced by emulsion polymerization using a water-soluble initiator such as ammonium persulfate or potassium persulfate.

The acrylic copolymer (A) may be crosslinked for the purpose of improving heat resistance and cohesive force. As the cross-linking agent used for such cross-linking, polyisocyanate, epoxy resin, melamine resin, aziridine compound, polyvalent metal salt, metal chelate and the like are used. In the present invention, the tackifying resin (B) obtained by combining the low softening point resin (Ba) and the high softening point resin (Bb) as described above is used.

The low softening point resin (Ba) has a softening point of 80 ° C. or higher and lower than 140 ° C., which is sufficient if the softening point of the resin (Ba) is lower than 80 ° C. If the heat resistance is not obtained and the softening point is 140 ° C. or higher, the Tg of the pressure-sensitive adhesive becomes too high and the adhesion to various adherends such as low-polarity adherends decreases. Moreover, although the softening point of the high softening point resin (Bb) is 140 ° C. or higher and lower than 200 ° C., the softening point of the resin (Bb) is 140 ° C. or higher.
If it is lower than 0 ° C, the peel resistance to the low-polarity adherend is lowered, and if the softening point is 200 ° C or higher, the Tg of the pressure-sensitive adhesive becomes too high and the adhesiveness is lowered.

In the present invention, the compounding amount of the tackifying resin (B) is 1 to 40 parts by weight based on 100 parts by weight of the acrylic copolymer (A). If the amount is less than 1 part by weight, the effect of adding the tackifying resin is not recognized, and sufficient adhesive force cannot be obtained for various adherends including low-polarity adherends.
On the other hand, if it exceeds 40 parts by weight, the pressure-sensitive adhesive becomes too hard and sufficient initial adhesive force cannot be obtained. The compounding ratio of the low softening point resin (Ba) and the high softening point resin (Bb) in the tackifying resin (B) of the present invention is 2.5% by weight or more and 75% by weight or more in the compounding ratio x as described above. It is less than or equal to weight%.
This is because if the compounding ratio x is less than 2.5% by weight, the peel resistance to the low-polarity adherend is not improved, and if it exceeds 75% by weight, the pressure-sensitive adhesive becomes too hard and a sufficient initial adhesive force is obtained. Because you cannot get it.

[0013]

In the present invention, the low softening point resin (Ba) and the high softening point resin (Bb) are added to the acrylic copolymer (A).
The tackifying resin (B) obtained by combining the above is contained in a specific ratio. Thus, in the present invention, since the tackifying resin (B) contains the low softening point resin (Ba),
High adhesion to various adherends including low polarity adherends. Further, since it contains the high softening point resin (Bb), it is possible to maintain a sufficient cohesive force even at high temperatures.
In addition, as the tackifying resin (B), by using the low softening point resin (Ba) and the high softening point resin (Bb) as described above in combination at a specific blending ratio, Although it is not clear, the constant load peeling force for the low-polarity adherend is dramatically improved.

[0014]

The present invention will be described in detail below with reference to examples and comparative examples according to the present invention. Example 1 A separable flask equipped with a cooling tube, a stirrer and a thermometer was used. 97 parts by weight of butyl acrylate and 3 acrylic acid were added.
Part by weight was dissolved in ethyl acetate so that the total amount of the monomers was 55/45 with respect to ethyl acetate, and 0.062 part by weight of benzoyl peroxide was added to the resulting solution as a polymerization initiator. .. This mixed solution was stirred under nitrogen reflux at 80 ° C. for 8 hours for polymerization to obtain a pressure-sensitive adhesive solution, that is, an acrylic copolymer resin solution.

N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide) (HDU) as a cross-linking agent was added to the above acrylic copolymer resin solution in an amount of 0.1%.
The adhesive composition of Example 1 was prepared by blending 05 parts by weight and a predetermined amount of the tackifying resin shown in Table 1. The pressure-sensitive adhesive composition obtained as described above was coated on release paper so that the thickness after drying was 75 μm, and then dried at a temperature of 110 ° C. for 5 minutes. Then, the pressure-sensitive adhesive composition on the release paper was placed on a non-woven fabric and pressure-bonded with a roll. This operation was also performed on the other side of the nonwoven fabric to obtain a nonwoven fabric-based double-sided tape.

Example 2 As shown in Table 1, a non-woven fabric-based double-sided tape was obtained in the same manner as in Example 1 except that the type of tackifying resin blended was changed. Example 3 The monomer composition ratio of the acrylic copolymer was butyl acrylate / 2-ethylhexyl acrylate / acrylic acid = 79/18/3, and as shown in Table 1, the type of tackifying resin to be blended. A nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 1 except that

Example 4 As shown in Table 1, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the type of tackifying resin to be blended was changed. Example 5 As shown in Table 1, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 1 except that the blending ratio of the tackifying resin to be blended was changed. Example 6 As shown in Table 1, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the blending ratio of the tackifying resin to be blended was changed.

Example 7 As shown in Table 1, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 1 except that the blending ratio of the tackifying resin to be blended was changed. Example 8 As shown in Table 1, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the type and the blending ratio of the tackifying resin to be blended were changed. Example 9 As shown in Table 1, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the type and the blending ratio of the tackifying resin to be blended were changed.

Example 10 As shown in Table 1, a non-woven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the kind and the mixing ratio of the tackifying resin to be mixed were changed. Example 11 As shown in Table 1, a non-woven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the type and the blending ratio of the tackifying resin to be blended were changed.

Comparative Example 1 As shown in Table 2, a non-woven fabric substrate double-sided tape was obtained in the same manner as in Example 1 except that the tackifying resin was not added. Comparative Example 2 As shown in Table 2, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the tackifying resin was not added. Comparative Example 3 As shown in Table 2, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 1 except that only the disproportionated rosin resin was used as the tackifying resin.

Comparative Example 4 As shown in Table 2, a non-woven fabric substrate double-sided tape was obtained in the same manner as in Example 3 except that only hydrogenated rosin resin was used as the tackifying resin. Comparative Example 5 As shown in Table 2, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 1 except that the total amount of the tackifying resin compounded was outside the range of the present invention. Comparative Example 6 As shown in Table 2, a nonwoven fabric-based double-sided tape was obtained in the same manner as in Example 3 except that the total amount of the tackifying resin compounded was outside the range of the present invention.

One side of the non-woven fabric-based double-sided tape obtained as described above was backed with a polyethylene terephthalate (PET) film having a thickness of 38 μm to prepare a test tape piece, and the following physical property tests were conducted. (1) SP adhesive strength According to JIS Z0237, a tape was attached to a SUS304 plate with a width of 20 mm, left at 23 ° C. for 20 minutes, and then the 180 ° peel strength was measured. Pulling speed is 3
It was set to 00 mm / min. (2) Adhesive strength of polypropylene (PP) A tape is attached to a PP plate with a width of 20 mm, and the tape is kept at 23 ° C. for 2 hours.
After leaving for 0 minutes, the 180 ° peel strength was measured. The pulling speed was 300 mm / min.

(3) Holding power (80 ° C.) At room temperature, a tape was attached to a SUS304 plate in a size of 20 × 20 mm, left at 80 ° C. for 20 minutes, then a load of 1 kg was applied, and a shift after 1 hour ( Or the fall time) was measured. (4) Polypropylene (PP) 90 ° constant load peeling force (8
0 ° C) At room temperature, attach tape to PP plate with a width of 20 mm,
After leaving it at 80 ° C for 20 minutes, apply a load of 80g,
Peeling was performed in the direction of 90 °, and the peeling length per unit time was measured.

[0024]

[Table 1]

[0025]

[Table 2]

In the examples according to the present invention, not only SP adhesive strength but also PP adhesive strength are excellent, and it can be seen that the adhesive strength to polypropylene is high. Also holding power and PP
It can be seen that the peeling force under constant load is also excellent and the heat resistance is also excellent. On the other hand, in Comparative Examples 1 and 2 to which the tackifying resin was not added, the SP adhesive strength and the PP adhesive strength were poor, and the PP constant load peeling strength was also poor. Further, in Comparative Examples 3 and 4 in which only the low softening point resin was added as the tackifying resin, the holding force and the PP constant load peeling force were poor and the heat resistance was poor. Further, Comparative Examples 5 and 6 in which the tackifying resin is contained in the range of the present invention or more.
Shows that the SP adhesive strength is low, and a slip adhesive is generated in the PP adhesive strength test, and sufficient adhesive strength cannot be obtained.

[0027]

As is clear from the above, the acrylic pressure-sensitive adhesive composition of the present invention is a combination of a low-softening point resin and a high-softening point resin as tackifying resins in a predetermined compounding ratio, and a predetermined amount of this resin. Since it is blended, it has high adhesiveness to low-polarity adherends such as olefin resins, and can maintain sufficient cohesive force even at high temperatures, exhibiting excellent heat resistance. Further, by containing the tackifying resin in such a combination, the constant load peeling force for the low-polar adherend is dramatically improved.

Claims (1)

[Claims] 1. The following general formula CH ₂ ═CR ¹ —COOR ² (wherein R ¹ is H or CH ₃ and R ² has 2 to 18 carbon atoms).
Which represents an alkyl group of
It contains an acrylic copolymer (A) and a tackifying resin (B) having 0 to 100% by weight and 0 to 20% by weight of another monomer copolymerizable with these monomers as a copolymerization component. An acrylic pressure-sensitive adhesive composition, wherein the tackifying resin (B) has a softening point of 80 ° C. or higher and 140 ° C.
Low softening point resin (B-a) of less than and softening point 140 ° C or higher 2
A combination of a high softening point resin (B-b) of less than 00 ° C, and a high softening point resin (B- in the tackifying resin (B).
Acrylic in which the compounding ratio of b) is 2.5 to 75% by weight, and the addition number of the tackifying resin (B) is 1 to 40 parts by weight with respect to 100 parts by weight of the acrylic copolymer (A). -Based pressure-sensitive adhesive composition.