JPH0770244A - Resin for tacky agent - Google Patents

Abstract

PURPOSE:To obtain the subject resin useful as a tacky sheet, tacky film, etc., having a specific glass transition temperature and excellent balance of adhesion, cohesive force, tack, etc., by copolymerizing specific monomers. CONSTITUTION:This resin for a tacky agent is a resin having-70 to-10 deg.C glass transition temperature and obtained by copolymerizing (A) >=60wt.% of a (meth) acrylate-based monomer or a vinyl ether-based with (B) 0.1-25wt.% of an N-vinylcarboxylic acid amide monomer of the formula (R1 and R2 are each H, a 1-4C alkyl).

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 resin that constitutes a pressure-sensitive adhesive layer such as a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive film, and a pressure-sensitive adhesive paper, and in particular, paper, skin, polyolefin resin, vinyl chloride resin, etc. The present invention relates to a pressure-sensitive adhesive resin having good adhesiveness and cohesiveness to adherends.

[0002]

2. Description of the Related Art Generally, rubber adhesives and acrylic adhesives are used as this type of adhesive resin. The rubber-based pressure-sensitive adhesive is mainly composed of natural rubber, synthetic rubber such as NBR / SBR and tackifying resin, and the acrylic-based pressure-sensitive adhesive is mainly composed of acrylic acid ester copolymer. . These adhesive resins are used by themselves for adhesion of adherends, and are also used in the form of adhesive tape or adhesive sheet by holding them in layers on a base material, or both sides covered with release paper. It is used in the form of adhesive tape.

Generally, the adhesive force is said to involve the adhesive force at the interface, the cohesive force (holding force) of the adhesive and the tack. Especially, in order to improve the heat resistance of the pressure-sensitive adhesive, the shape retention of the pressure-sensitive adhesive layer, the prevention of adhesive residue on the adherend, etc. It is being appreciated. However, if an attempt is made to increase the molecular weight in order to improve the cohesive force, there are disadvantages that the tack force and the like are reduced and the viscosity is increased, so that the workability is reduced. Therefore, it is not possible to use an adhesive resin having a too high molecular weight. Further, when the content of (meth) acrylic acid or the like is increased, the holding power is improved, but the tack is reduced. Furthermore, although increasing the glass transition temperature of the resin improves the heat resistance,
After all, the tack is reduced. Therefore, in consideration of the balance of tackiness, cohesiveness, holding power, etc., it is put to practical use as a composition containing a tackifier and the like.

In order to increase the adhesive force to the adherend and to improve the cohesive force, Japanese Patent Laid-Open No. 4-154882 discloses an N method.
-A method of copolymerizing vinylpyrrolidone with an acrylic pressure-sensitive adhesive resin is shown, but the cohesive force to an adherend having a strong polarity (for example, vinyl chloride) is improved but Tg is increased and tack is reduced. . Further, JP-A-2-70785 discloses a method of copolymerizing acrylamide or methacrylamide and an unsaturated monomer having a hydroxyl group with an ethylenically unsaturated monomer. Although it is supposed to improve the cohesive force, acrylamide or methacrylamide is easily hydrolyzed,
It becomes difficult to put an acid or alkali substance in the pressure-sensitive adhesive, or it may be hydrolyzed depending on the pH of the adherend, and a sufficient pressure-sensitive adhesive force may not be obtained. In addition, when it is used for an adhesive tape for skin, etc., the hydrolyzed residue becomes a carboxylic acid, and the skin irritation of ammonia gas generated further becomes a problem, so that it cannot be used for skin application.

[0005]

When the molecular weight is increased in order to improve the adhesive force with the conventional resin for adhesives, particularly to improve the cohesive force, the tack force and the like are lowered and the viscosity is reduced. There is a drawback in that workability is lowered because of the high cost. Therefore, since it is not possible to use a resin for a pressure-sensitive adhesive having a too high molecular weight, it is attempted to improve the tackiness by an additive such as a tackifier, but the balance of the tackiness, cohesiveness, holding power, etc. There is nothing left out. In view of the above circumstances, the present invention is adhesiveness with a resin alone,
It is an object of the present invention to provide an excellent pressure-sensitive adhesive resin in which cohesiveness (holding power), tackiness and the like are well balanced.

[0006]

In the present invention, in order to solve this problem, a composition which improves the cohesive force by copolymerizing an N-vinylcarboxylic acid amide monomer and does not impair the tack force and the like. It was found that a resin for pressure-sensitive adhesives which meets the above various purposes can be obtained by the ratio, and the present invention has been completed.

That is, according to the present invention, 60% by weight or more of the (meth) acrylate-based and / or vinyl ether-based monomer and 0.1 to 2 of the N-vinylcarboxylic acid amide monomer are used.
Obtained by copolymerizing 5% by weight and having a glass transition temperature of -7
It is in the resin for pressure-sensitive adhesives, which is characterized in that it is 0 ° C to -10 ° C.

The (meth) acrylate as the main monomer used in the production of the adhesive resin according to the present invention includes methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-methylbutyl (meth) acrylate, 3-methylbutyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, (meth ) Isobutyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic acid 4
-Cyanobutyl, (meth) acrylic acid 5-cyano-3-
Oxapentyl, 2-ethoxyethyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxyethyl (meth) acrylate, 4-methoxypropyl (meth) acrylate, etc. Acrylic acid or methacrylic acid cyano Group, an alkyl ester or a cycloalkyl ester which may be substituted with an alkoxy group, and as a vinyl ether type, methyl vinyl ether,
Ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, etc., but not limited to these monomers, (co) polymers of these monomers, A material having a low glass transition temperature (Tg) is used. The content of these main monomers is limited to 60% by weight or more. If this content is less than 60% by weight, the resin for pressure-sensitive adhesive becomes too hard and the adhesive strength is lowered. More preferably, it is 75% by weight or more.

The N-vinylcarboxylic acid amide monomer is a compound which forms the following repeating unit formula (1).

[Chemical 1] (However, in the formula, R ₁ and R ₂ are hydrogen atoms or C 1 to C 4
Represents an alkyl group. )

Specifically, N-vinylformamide, N-
Vinyl acetamide, N-vinyl propionic amide, N-vinyl butyric amide, N-vinyl isobutyric amide, N-methyl-N-vinyl formamide,
N-methyl-N-vinylacetamide, N-methyl-N
-Vinyl propionic amide, N-methyl-N-vinyl butyric amide, N-methyl-N-vinyl isobutyric amide, N-ethyl-N-vinyl formamide,
N-ethyl-N-vinylacetamide, N-ethyl-N
-Vinyl propionic amide, N-ethyl-N-vinyl butyric amide, N-ethyl-N-vinyl isobutyric amide, N-propyl-N-vinyl formamide, N-propyl-N-vinyl acetamide, N- Propyl-N-vinyl propionic amide, N-propyl-N-vinyl butyric amide, N-propyl-N-vinyl isobutyric amide, N-isopropyl-N-vinyl formamide, N-isopropyl-N-vinyl acetamide , N-isopropyl-N-vinylpropionic amide, N-isopropyl-N-vinylbutyric amide, N-isopropyl-N-vinylisobutyric amide, N-butyl-N-vinylformamide, N-butyl-N -Vinylacetamide, N-butyl-N-vinylpropionic amine , N- butyl -N- vinyl butyric amide, N- butyl -N- vinyl isobutyrate butyric amide, N- isobutyl -N- vinylformamide, N-
Isobutyl-N-vinylacetamide, N-isobutyl-N-vinylpropionic amide, N-isobutyl-
Examples thereof include N-vinyl butyric amide and N-isobutyl-N-vinyl isobutyric amide, among which N-
Vinylacetamide is most preferred. By using N-vinylcarboxylic acid amide, the adhesive force and cohesive force with respect to the adherend having a strong polarity (vinyl chloride resin or the like) are enhanced. When the N-vinylcarboxylic acid amide is less than 0.1% by weight, the cohesiveness is reduced, and a phenomenon of adhesive residue on the adherend when peeling is observed. On the other hand, when the content is 25.0% by weight or more, the resin for pressure-sensitive adhesive becomes too hard and the adhesive strength is lowered. Also, the hydrophilicity is increased and the water resistance is weakened. A particularly preferable content is 3.0 to 20.0% by weight.

Further, a copolymerizable monomer may be copolymerized. For example, unsaturated acids such as acrylic acid and methacrylic acid, styrene monomers such as styrene and α-methylstyrene, unsaturated dibasic acids such as maleic acid and fumaric acid,
39.9% by weight of hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, and copolymerizable unsaturated monomers such as acrylonitrile and vinyl acetate / isopropenyl acetate
The following may be contained. If it exceeds 39.9% by weight, the pressure-sensitive adhesive resin becomes too hard and the adhesive strength is lowered.

The Tg of the pressure-sensitive adhesive resin used must be -70 to -10 ° C in order to develop its adhesive performance. More preferably, it is -70 to -40 ° C. T
When g is less than -70 ° C, cohesiveness and heat resistance are lowered, and when it exceeds -10 ° C, tack is lowered and cold resistance is poor.

The pressure-sensitive adhesive resin is optionally crosslinked for the purpose of maintaining the physical properties of the pressure-sensitive adhesive at high temperature and increasing the cohesive force of the double-sided tape. When cross-linked by copolymerizing with the monomer of the present invention, as a cross-linking agent, ethylene glycol dimethacrylate / ethylene glycol diacrylate / diethylene glycol dimethacrylate / diethylene glycol diacrylate / polyethylene glycol dimethacrylate / polyethylene glycol diacrylate / trimethylol Propane trimethacrylate
Trimethylolpropane triacrylate / N, N'-
1,4-butylene bis (N-vinylacetamide)
N, N'-1,6-hexylenebis (N-vinylacetamide) N, N'-1,10-decylenebis (N-vinylacetamide), N, N'-3-oxa-1,5-
Pentylenebis (N-vinylacetamide) ・ N, N '
-3,6-Dioxa-1,8-octylenebis (N-vinylacetamide) .N, N'-xylenebis (N-vinylacetamide) .N, N'-diacetyl-N, N '
A monomer having two or more ethylenically unsaturated double bonds such as divinyl-1,4-bisaminomethylcyclohexane can be used. However, the monomer having two or more ethylenically unsaturated double bonds is preferably used in an amount of 1.5% by weight or less. If it exceeds 1.5% by weight, gelation tends to occur during polymerization.

The method for preparing the adhesive resin solution of the present invention is as follows:
(Meth) acrylate and / or vinyl ether type monomer and N-vinylcarboxylic acid amide are dissolved in a suitable solvent by a required amount each, and if necessary, further copolymerizable unsaturated monomer or two or more It is adjusted by adding a required amount of a monomer having an ethylenically unsaturated double bond, adding a polymerization initiator, raising the temperature of the mixed solution, and conducting a polymerization reaction. The polymerization reaction is substantially carried out by solution polymerization. In this case, examples of the reaction solvent generally include esters such as methyl acetate / ethyl acetate, aromatic hydrocarbons such as benzene / toluene / xylene, ketones such as acetone / methyl ethyl ketone / methyl isobutyl ketone, and the like. They are used alone or in combination as appropriate. As a polymerization method, in addition to solution polymerization, any method such as emulsion polymerization and suspension polymerization can be carried out. As the polymerization initiator, various known initiators such as various peroxides such as benzoyl peroxide / lauroyl peroxide and azo compounds such as azobisisobutyronitrile may be appropriately used alone or in combination. These are usually used in a proportion of 0.01 to 1 part by weight with respect to 100 parts by weight of the monomer.

The molecular weight of the pressure-sensitive adhesive resin of the present invention is not particularly limited, but the standard polystyrene equivalent weight average molecular weight by gel permeation chromatography (GPC) is 200,000 to 1,000,000, and preferably, It is 400,000 to 800,000.

The copolymer obtained in this way can also be crosslinked later for the purpose of the above-mentioned crosslinking. As the post-crosslinking agent for the copolymer, a crosslinking agent such as an isocyanate compound, an epoxy compound or an organic metal complex is used. Cross-linking is an electron beam irradiation method, a thermal cross-linking method using a peroxide such as benzoyl peroxide as a catalyst,
It is carried out by a known method such as a curing method using an isocyanate crosslinking agent. In the case of crosslinking with an isocyanate crosslinking agent, a crosslinking point monomer such as 2-hydroxyalkyl (meth) acrylate is added in an amount of 0.1 to 1 with respect to the main monomer.
Copolymerized by weight%. When an α, β unsaturated carboxylic acid is used as the crosslinking point, the amount used is preferably as small as possible and is 0.5% by weight or less.

To the pressure-sensitive adhesive according to the present invention, a tackifying resin such as xylene resin, phenol-modified xylene resin, phenol resin, rosin or rosin-modified resin may be added in addition to the resin for the pressure-sensitive adhesive. There is also. The addition amount of the tackifying resin is 30 parts by weight or less based on 100 parts by weight of the adhesive resin. Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0018]

【Example】

Example 1 80 g of butyl acrylate, 1 N-vinylacetamide
0 g and 10 g of vinyl acetate were dissolved in 900 g of ethyl acetate, the temperature was raised to 70 ° C. under a stream of nitrogen, 0.2 g of azobisisobutyronitrile was added as an initiator, and 7
Polymerization was carried out at 0 ° C. for 4 hours to obtain a resin solution for pressure-sensitive adhesive.

The weight average molecular weight and glass transition point of the obtained polymer were measured by the following methods. [Weight average molecular weight] The resin concentration of the adhesive resin solution was set to 0.
A 5% solution was prepared with ethyl acetate and measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene. The results are shown in Table 1. [GPC conditions] Column: Showa Denko K.K./trade name Shodex GPC KF-804 + 803 + 801 in series Eluent: Tetrahydrofuran Column temperature: 40 ° C Flow rate: 1 ml / min Detector: Differential refractometer

[Glass Transition Point] Each of the pressure-sensitive adhesive resin solutions obtained in the examples was vacuum dried at 50 ° C. for 4 hours to evaporate the water content, and each pressure-sensitive adhesive resin solution was subjected to a differential scanning calorimeter (Seiko Denshi). The glass transition point was measured using Kogyo Co., Ltd. Next, the obtained resin solution for pressure-sensitive adhesive was applied to a polyester film having a thickness of 38 μm so as to have a thickness of 70 μm after drying and dried at a temperature of 100 ° C. for 5 minutes to prepare a pressure-sensitive adhesive sheet.

The physical properties of the obtained pressure-sensitive adhesive sheet were evaluated by the following methods. However, each evaluation was performed at 25 ° C. and 65% RH. The results are shown in Table 1. [Tack force] It was measured using a tack tester (manufactured by Rigaku Kogyo Co., Ltd.). A test piece cut out into a disk having a diameter of 15 mm was used. The measurement conditions were such that the contact time was 5 sec, the probe moving speed was 5 mm / sec, the load was 180 g, and the probe used was stainless steel with a diameter of 10 mm wiped with methanol, and the average value of 5 measurements was taken.

[Adhesive force (180 ° peeling force)] 30 mm x
A 70 mm test piece was reciprocated once with a 2 kg pressure roller at a moving speed of 2 cm / sec and pressure-bonded onto a stainless steel plate wiped well with ethanol. From stainless steel plate, 3
The stress at 180 ° peeling at 0 cm / min was measured three times with a digital force gauge, and the average was taken.

[Holding power] A test piece having a width of 25 mm and a length of 100 mm was prepared, and the adhesive surface had a length of 25 mm and a width of 25 mm.
The portion was attached to a stainless steel plate (SUS304) polished with sandpaper # 280, and the time (hour) until the pressure-sensitive adhesive sheet dropped from the stainless steel plate under a load of 1 kg was measured.

[Stability to Aqueous Acid and Alkali Aqueous Solution] A buffer solution having a pH of 3 or 10 was dropped on the obtained pressure-sensitive adhesive sheet and kept at 30 ° C., and the state of the sheet was visually observed and smelled. ○: No change in appearance, no odor △: Change in appearance such as swelling, no odor ×: Change in appearance such as swelling, odor

Example 2 Polymerization was performed in the same manner as in Example 1 except that butyl acrylate of Example 1 was replaced with ethyl vinyl ether to obtain a resin solution for pressure-sensitive adhesive. The molecular weight and glass transition point of this resin solution were determined according to Example 1
It measured similarly to. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 3 0.1 g of N, N'-methylenebisacrylamide was added as a crosslinking agent in Example 1 and polymerization was carried out in the same manner as in Example 1 to obtain a resin solution for pressure-sensitive adhesive. The molecular weight and glass transition point of this resin solution were measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 4 65 g of 3-methoxypropyl acrylate, 25 g of N-vinylacetamide, 10 g of vinyl acetate and 9 parts of toluene
It was dissolved in 00 g, heated to 70 ° C. under a nitrogen stream, 0.2 g of azobisisobutyronitrile was added as an initiator, and polymerization was continued for 4 hours at 70 ° C. to obtain a resin solution for pressure-sensitive adhesive. It was The molecular weight and glass transition point of this resin solution were measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 5 Polymerization was carried out in the same manner as in Example 1 except that N-vinylacetamide of Example 2 was replaced with N-vinylformamide to obtain a resin solution for pressure-sensitive adhesive. The molecular weight and glass transition point of this resin solution were measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 6 80 g butyl acrylate, 1 N-vinylacetamide
g, 19 g of acrylic acid was dissolved in 900 g of ethyl acetate, the temperature was raised to 70 ° C. under a nitrogen stream, 0.2 g of azobisisobutyronitrile was added as an initiator, and the mixture was kept at 7
Polymerization was carried out at 0 ° C. for 4 hours to obtain a resin solution for pressure-sensitive adhesive.
The molecular weight and glass transition point of this resin solution were measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 7 45 g of 3-methoxypropyl acrylate, 20 g of stearyl mecrylate, 25 g of N-vinylacetamide,
Vinyl acetate (10 g) was dissolved in toluene (900 g), the temperature was raised to 70 ° C. under a nitrogen stream, azobisisobutyronitrile (0.2 g) was added as an initiator, and polymerization was continued for 4 hours at 70 ° C. A resin solution for agent was obtained. The molecular weight and glass transition point of this resin solution were measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 90 g of butyl acrylate and 10 g of vinyl acetate were dissolved in 900 g of toluene and the temperature was raised to 70 ° C. under a nitrogen stream, and 0.2 g of azobisisobutyronitrile was used as an initiator.
Was added, and the mixture was polymerized as it was at 70 ° C. for 4 hours to obtain a resin solution for pressure-sensitive adhesive. The molecular weight of this resin solution was measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 50 g of N-vinylacetamide and 50 g of 3-methoxypropyl acrylate were dissolved in 900 g of ethyl acetate,
This was heated to 70 ° C under a nitrogen stream, 0.2 g of azobisisobutyronitrile was added as an initiator, and the mixture was kept at 70 ° C.
Polymerization was carried out for 4 hours in the above state to obtain a resin solution for adhesive. The molecular weight of this resin solution was measured in the same manner as in Example 1. Also,
An adhesive sheet was prepared in the same manner as in Example 1 using the obtained resin solution, and the physical properties of the adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 N-vinylacetamide 5 g, butyl vinyl ether 5
0 g and 45 g of acrylic acid were dissolved in 900 g of ethyl acetate, the temperature was raised to 70 ° C. under a nitrogen stream, and 0.2 g of azobisisobutyronitrile was added as an initiator.
Polymerization was carried out at 0 ° C. for 4 hours to obtain a resin solution for pressure-sensitive adhesive.
The molecular weight of this resin solution was measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 1 except that N-vinylacetamide of Example 2 was replaced with acrylamide to obtain an adhesive resin solution. The molecular weight and glass transition point of this resin solution were measured in the same manner as in Example 1. A pressure-sensitive adhesive sheet was prepared using the obtained resin solution in the same manner as in Example 1, and the physical properties of the pressure-sensitive adhesive sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

From the results shown in Table 1, the resin for pressure-sensitive adhesives of the present invention has excellent performance with well-balanced adhesiveness, cohesiveness (holding power), tackiness, etc., and is stable to pH. I understand.

[0036]

[Table 1]

[0037]

EFFECTS OF THE INVENTION According to the present invention, the resin alone has excellent performance in which the tackiness, cohesiveness (holding power), tackiness, etc. are well balanced, and particularly paper, skin, polyolefin resin, vinyl chloride resin It is possible to provide a resin for an adhesive that has good adhesiveness and cohesiveness to an adherend such as a resin, and its application is an adhesive that constitutes an adhesive layer such as an adhesive sheet / adhesive film / adhesive paper. It can be used as a resin for agents, for example, kraft tape for corrugated cardboard, gum tape, address seals / labels for courier and parcels, industrial products such as masking tape for soldering, adhesive tape for household daily use, etc.
It is possible to provide very useful items such as labels, hair removal tapes, sanitary products such as sanitary napkins, and transdermal preparations for medical use.

Claims (1)

[Claims] 1. A glass obtained by copolymerizing 60% by weight or more of a (meth) acrylate-based and / or vinyl ether-based monomer and 0.1 to 25% by weight of an N-vinylcarboxylic acid amide monomer, and a glass. A resin for pressure-sensitive adhesive, which has a transition temperature of −70 ° C. to −10 ° C.