JPH01141970A - Tacky adhesive - Google Patents

Abstract

PURPOSE:To obtain a tacky adhesive which is excellent in processability and can be used for tacky tapes, etc., by performing the one-stage polymerization of a mixture comprising an acrylate monomer, a COOH group-containing monomer, an OH group-containing monomer and a vinyl monomer other than the above. CONSTITUTION:A tacky adhesive which is a copolymer of a composition of 64-86.00wt.% at least one acrylate monomer (A) (e.g., n-butyl acrylate), 3-5wt.% at least one COOH group-containing monomer (B) (e.g., methacrylic acid), 0.01-1wt.% at least one OH group-containing monomer (C) (e.g., 2- hydroxyethyl methacrylate) and 10-30wt.% at least one vinyl monomer (D) other than the above (e.g., vinyl acetate or styrene) and obtained by performing the one-stage polymerization of this monomer mixture. This tacky adhesive can be used for various tacky adhesive articles such as tacky adhesive tapes and tacky labels and is excellent in tacky adhesive force, adhesive force and cohesive force and excellent in, especially, processability and can be simply provided by one-stage polymerization.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an adhesive used for various adhesive processed products such as adhesive tapes and adhesive labels, and the adhesive has particularly excellent processing suitability, and is produced by one-step polymerization. This is what we provide.

[Prior Art] Adhesives are required to have appropriate adhesive strength, adhesion strength, and cohesive strength, and in particular, processability is also required for adhesives for adhesive labels such as labels, stickers, and stickers.

Generally, when trying to improve the suitability for processing such as side tack and punching, the cohesive force of the adhesive is increased (hardened).
Therefore, there is a phenomenon in which adhesive strength and adhesive strength decrease as cohesive strength increases, so it is necessary to strike an appropriate balance between physical properties and processability.

Conventionally, acrylic adhesives have been known as typical adhesives for adhesive labels, and these adhesives can be made by increasing the crosslinking density, adding plasticizers, tackifiers, or blending other hard components. By this method, the hardness is adjusted to be suitable for side tacking, punching, etc., and it is put into practical use.

Such pressure-sensitive adhesives with improved processing suitability are also described in the literature; for example, in JP-A-57-2374, an acrylic ester monomer and an acrylic monomer containing a functional group (carboxyl group or hydroxyl group) are graft-polymerized, That is, a pressure-sensitive adhesive manufactured in two stages is shown. One of the examples of the publication includes (a) an acrylic ester monomer, (
There are also examples of using b) a carboxyl group-containing monomer, (C) a hydroxyl group-containing monomer, and (d) a vinyl monomer other than the above, and although the polymerization method and monomer usage ratio are different from the present application, they are the same type of monomer. In terms of the combination of the two, examples are given where the trajectory is negative.

[Problems to be solved by the invention]However, when adding a plasticizer, tackifier, or hard component to an acrylic adhesive, coloring,
There is a risk that problems may occur in terms of weather resistance under paper, etc., and it is considered advantageous to satisfy such requirements only by improving the composition of the copolymer. On that point, JP-A-57-23
The method of Publication No. 74 can be expected to be put to practical use, but according to the study of the present inventors, although the physical properties and processability of the adhesive are satisfactory, since it is a two-stage polymerization, the restraining time during polymerization is long.
It has become clear that there are many limitations in manufacturing on an industrial scale, such as the large amount of polymerization initiator used, and the resulting adhesive tends to gel and has poor storage stability.

Therefore, the present inventors attempted one-stage polymerization, which is an industrially more advantageous method than the two-stage polymerization method described above, that is, a method in which each monomer is mixed at once and polymerized, but the conditions described in the publication were adopted as they were. However, the objective could not be achieved simply by changing the two-stage polymerization to the one-stage polymerization.

[Means for Solving the Problems] Therefore, as a result of further research, the present inventors found that (a) at least one of the acrylic acid ester monomers is 64 to 8
6.99% by weight (b) 3 to 5% by weight of at least one carboxyl group-containing monomer (c) 0.01 to 1% by weight of at least one hydroxyl group-containing monomer (d) Vinyl monomers other than the above At least one type is l
The present inventors have discovered that a copolymer having a composition of θ to 30% and which is obtained by one-stage polymerization of a mixture of the above monomers can achieve the above object, and have completed the present invention.

The feature of the present invention is that the copolymer is obtained by one-stage polymerization as described above, and the content of (b) carboxyl group-containing monomer and (c) hydroxyl group-containing monomer component is limited within a certain range. It is in. The resulting adhesive has physical properties and processability equivalent to those of the adhesive disclosed in JP-A No. 57-2374, and the adhesive used in the present application has a shorter manufacturing time and a lower amount of polymerization initiator. It has remarkable effects in terms of industrial production, such as the fact that the pressure-sensitive adhesive is small in amount and the preservability of the resulting adhesive is excellent.

The acrylic copolymer in the present invention is prepared by adding (a)
.

The mixed monomers (b), (c), and (d) are dissolved, a polymerization initiator is added, the temperature is raised, and the mixture is reacted, or in some cases, the mixed monomers or polymerization initiator is added to remove the reaction heat. React by adding dropwise. Any method such as solution polymerization, emulsion polymerization, and turbidity polymerization can be used as the polymerization method, but solution polymerization and emulsion polymerization are practical. In solution polymerization, solvents generally include esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as benzene, toluene, and xylene, alicyclic hydrocarbons such as cyclohexane, and ketones such as acetone and methyl ethyl ketone. or used in combination, but is not limited to these. When deciding on a solvent, it is necessary to take into account the boiling point of the solvent, the solubility and molecule m of the obtained copolymer, and workability. For example, ethyl acetate or a mixed solvent of ethyl acetate and toluene, etc. Particularly preferred. In emulsion polymerization, glycerin monostearate, polyoxyethylene phenyl ether, sodium lauryl sulfate, etc. can be used as emulsifiers.

Further, as the polymerization initiator, known polymerization initiators such as various peroxides such as benzoyl peroxide and lauryl peroxide, and azo compounds such as azobisisobutyronitrile are used alone or in combination. These are usually used in a proportion of 0.2 to 0.5 parts by weight per 100 parts by weight of the monomer.

The adhesive of the present invention comprises (a) 64 to 86.99% by weight of an acrylic acid ester monomer, preferably 70 to 82% by weight, (b) 3 to 5% by weight of a carboxyl group-containing monomer,
Preferably 3.0 to 4.6% by weight, (c) hydroxyl group-containing monomer 0.01 to 1% by weight, preferably 0
．． 04 to 0.4% by weight (d) A copolymer having a composition of 10 to 30% by weight, preferably 15 to 25% by weight of vinyl monomers other than those mentioned above.

If the acrylic acid ester monomer content is less than 64% by weight, the adhesive becomes too hard and the processing suitability for side tack processing, punching processing, etc. is improved, but the adhesive strength and adhesion strength (decreased).

On the other hand, if it is more than 86.99% by weight, it becomes too soft, the cohesive force decreases, and the processing suitability for side tuck processing, punching processing, etc. becomes poor.

If the amount of the carboxyl group-containing monomer is less than 3% by weight, the cohesive force decreases and the shear strength decreases. On the other hand, if it is more than 5% by weight, it becomes too hard and the adhesive strength decreases.

If the content of the hydroxyl group-containing monomer is less than 0.01%, the cohesive force decreases. On the other hand, if it is more than 1% by weight,
When using a crosslinking agent, the crosslinking density becomes too high and the adhesive strength decreases.

If the amount of vinyl monomers other than those mentioned above is less than 10% by weight, the adhesive becomes too soft and the cohesive force decreases. On the other hand, if it is more than 30% by weight, it becomes too hard and the adhesive strength decreases.

As described above, one-stage polymerization cannot satisfy both the physical properties and processing suitability of the adhesive other than the composition range of the present application.

The ester of the acrylic acid ester monomer may be any ester such as methyl, ethyl, propyl, butyl, hexyl, etc.

Examples of carboxyl group-containing monomers include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, polycarboxylic acids such as maleic acid, fumaric acid, citraconic acid, glutaconic acid, and itaconic acid, and anhydrides thereof.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and N-methylol acrylamide. etc.

Examples of vinyl monomers other than those mentioned above include methacrylic acid alkyl esters such as methyl methacrylate and ethyl methacrylate, styrene, vinyl acetate, acrylonitrile, and acrylamide.

The adhesive of the present invention exhibits sufficient adhesive strength, adhesion strength, and cohesive strength even when used in various adhesive processed products, but in particular,
It is suitable for use in products that require processing suitability, such as adhesive labels, and is extremely practical.

The adhesive of the present invention may also contain rosin, rosin ester, hydrogenated rosin ester, phenol resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin, etc. Tackifiers, phthalates,
Plasticizers such as phosphoric acid ester, adipic acid ester, sepatic acid ester, phosphoric acid ester, polyester type, epoxy type, chlorinated paraffin, oils and fats such as animal and vegetable oils, mineral oil, silicone oil, titanium oxide, zinc white, carbonic acid Coloring agents such as calcium, UV inhibitors such as benzophenone, salicylate, benzotriazole, substituted acrylonitrile, inorganic compounds such as arsenous acid, suboxide steel, mercury oxide, organic mercury compounds, organic sulfur compounds, phenolic compounds , antifoaming agents such as organic copper compounds, antifoaming agents such as silicone emulsion, alcohols, thickeners such as polyvinyl alcohol, sodium polyacrylate, carboxymethylcellulose, methylcellulose, etc., are added. can.

[Function] (a) At least one acrylic acid ester monomer is 64 to 86.99% by weight (b) At least one carboxyl group-containing monomer is 3 to 5% by weight (c) At least one hydroxyl group-containing monomer 1 type is 0.01 to 1% by weight (d) At least one type of vinyl monomer other than the above is 1% by weight
The adhesive, which is a copolymer having a composition of 0 to 30i1tff [ and which is obtained by one-stage polymerization of a mixture of the above monomers, has adhesive strength, adhesion strength, and cohesive strength equivalent to that of conventional adhesives. It has the advantage that it has excellent processability and can be easily obtained by one-stage polymerization.

Example 1 A flask with a stirrer was charged with 759 g of ethyl acetate, 40 g of toluene, and 0.20 g of azobisisobutyronitrile (AIBN) as a polymerization initiator, and the temperature was raised to 86° C. while stirring. 2-ethylhexyl acrylate 67.29, n-butyl acrylate 1209
, vinyl acetate 36g, styrene 2.4g, methyl methacrylate 3.85g, acrylic acid 9.6g, methacrylic acid 0.249.2-hydroxyethyl methacrylate 0
．． 729 mixed monomer was added dropwise over 2 hours, and then A I B No. 1 dissolved in 20 g of toluene solvent was added.
5 g was charged into the mouth at the 3rd and 5th hour, and the reaction was carried out at the boiling point for 7 hours to obtain a copolymer.

Add toluene 1639 as a diluent to reduce the resin content to 43.0
A resin solution having a weight percent and a viscosity of 3800 cps was obtained.

The composition of the obtained copolymer was 28% by weight of 2-ethylhexyl acrylate and 50% by weight of n-butyl acrylate.
, 15% by weight of vinyl acetate, 1% by weight of styrene, 1.6% by weight of methyl methacrylate, 4% by weight of acrylic acid, 0.1% by weight of methacrylic acid, and 0.3% by weight of 2-hydroxyethyl methacrylate.

Next, the performance of the copolymer obtained above as an adhesive was evaluated.

To 100 parts by weight of the copolymer (solid content: 43% by weight solution), 1.0% of Coronate (NCO 13% by weight polyisocyanate) was added as a crosslinking agent.
Part by weight was added to produce an adhesive. Using this adhesive, the physical properties and processing suitability were evaluated using the following measuring methods, and the results are shown in Table 1.

○Using a shear strength autograph measuring machine, tensile speed 10 mm/min
Sample width: 10 mm x I: 0 mm, 0-grain force and pole tack (20°C), measured based on lrS Z 0237.

O side tack A test piece with a width of 50 x 50" was sandwiched between specified papers, and further pressed with a glass plate, a load of 5009/cm' was applied, and the amount of adhesive sticking out after 7 and 28 days after storage at 40°C was measured. Examined.

O-Punching Process Observation results obtained when a dead bone label was actually punched using a flat processing type punching machine.

Examples 1-3. Control Examples 1 to 6 Experiments were conducted according to the method of Example 1 using the reagents shown in Table 1.2. The results are shown in Table 1.2.

[Effects] As mentioned above, the viscosity agent of the present invention contains (2L) at least one acrylic acid ester monomer in an amount of 64 to 86.99% by weight (b) at least 1wt of a carboquinyl group-containing monomer
(c) At least one hydroxyl group-containing monomer is 0.0 to 1% by weight (d) At least one monomer other than the above is 1% by weight
It is a copolymer having a composition of 0 to 30% by weight, and is obtained by one-stage polymerization of a mixture of the above monomers. INDUSTRIAL APPLICABILITY The present invention is extremely useful industrially in that it can easily provide a viscous agent that has excellent adhesive strength, contact strength, and cohesive strength, and particularly has excellent processability through one-stage polymerization.

Claims (1)

Scope of Claims: (a) 64 to 86.99% by weight of at least one acrylic acid ester monomer (b) 3 to 5% by weight of at least one carboxyl group-containing monomer (c) 3 to 5% by weight of at least one acrylic acid ester monomer At least one type is 0.01 to 1% by weight (d) At least one type of vinyl monomer other than the above is 1% by weight
An adhesive that is a copolymer having a composition of 0 to 30% by weight and obtained by one-stage polymerization of a mixture of the above monomers.