JPH02178381A - Tacky agent and tacky sheet using same tacky agent - Google Patents

Abstract

PURPOSE:To obtain the subject composition useful for the tacky sheet such as a tacky tape or tacky label having excellent balance of tackiness, cohesive force and tack by mainly containing a mixture of copolymer containing (meth) acrylate as a main component and a specific compound. CONSTITUTION:The aimed composition is mainly composed of a mixture of a copolymer containing an acrylate and/or methacrylate as a main component and a compound (e.g. ethylene oxide additives of polyethylene glycol or polyoxyethylene phenylether) expressed by the formula (n is positive; R is H, 1-7C alkyl, phenyl, tolyl or 1-4C acyl). Besides, adding amount of the compound expressed by the formula is preferably 0.02-2wt.%.

Description

Detailed Description of the Invention (a) Purpose of the Invention [Field of Industrial Application] The present invention has an excellent balance of adhesive force, cohesive force, and tack;
The present invention relates to a pressure-sensitive adhesive composition useful for use in pressure-sensitive adhesive sheets such as pressure-sensitive adhesive tapes and pressure-sensitive adhesive labels.

[Conventional technology and its problems]

Currently, there are natural rubber-based, synthetic rubber-based, and acrylic ester-based adhesives, and these adhesives are applied to a base material and used in a wide range of applications in the form of adhesive sheets such as adhesive tapes and adhesive labels. ing.

Among these, acrylic ester adhesives have become widely popular in recent years due to their excellent adhesive properties and weather resistance.

However, when used for adhesive tapes, acrylic acid ester adhesives have a problem in that they have inferior cardboard sealing properties compared to rubber adhesives.

In order to solve this problem, efforts have been made to improve cohesion, which is considered to have the greatest influence conventionally. As a method for this purpose, the glass transition point of the copolymer constituting the adhesive is increased, the crosslinking density is increased, and the molecular weight is increased. However, even if such cohesive force improvement measures are implemented, the sealability of corrugated cardboard does not improve as much as expected, and when cohesive force is improved, adhesion force decreases.

The tank size had decreased significantly, and the balance between adhesive force, cohesive force, and tack was disrupted, making it difficult to use.

(B) Structure of the Invention [Means for Solving the Problems] The present inventors have completed the present invention as a result of intensive studies on the above-mentioned conventional problems.

That is, the present invention provides an adhesive composition R-0-( CH2CH,○)n-H (wherein, n is a positive number, and R is a hydrogen atom, an alkyl group having 7 or less carbon atoms, a phenyl group, a tolyl group, or an acyl group having 4 or less carbon atoms) It is.

) and a pressure-sensitive adhesive sheet having a layer of the above pressure-sensitive adhesive composition formed on the surface of a base material.

[Effect]

The pressure-sensitive adhesive composition of the present invention has an excellent balance of adhesive force, cohesive force, and tack, and can be used, for example, as a pressure-sensitive adhesive tape by applying the pressure-sensitive adhesive composition to a base material.

An adhesive tape with excellent sealing properties for cardboard. The corrugated board sealability of such an adhesive tape is greatly influenced by the ig gathering force of the adhesive composition used, but it is considered that the tape will not be satisfactory unless the adhesive strength and tack are also at a high level. The adhesive composition of the present invention uses an additive, which is a compound having the above structural formula, in an acrylic ester adhesive, so that, although the reason is not clear, there is no decrease in adhesive strength or tack, and the cohesive strength is improved. It was found that, for example, when the pressure-sensitive adhesive composition was applied to a base material to form a pressure-sensitive adhesive tape, the sealability of corrugated cardboard was improved.

(Adhesive composition) As described above, the adhesive composition of the present invention is mainly composed of a mixture of an acrylic acid alkyl ester adhesive and a specific additive. The acrylic ester adhesive is a copolymer containing acrylic ester and/or methacrylic ester (hereinafter abbreviated as (meth)acrylic ester) as a main component.

<Acrylic ester adhesive> In the copolymer that is the acrylic ester adhesive of the present invention, the preferable content of the (meth)acrylic acid alkyl ester is the sum of all monomers constituting the copolymer. The amount is 50% by weight or more, more preferably 60% by weight or more.

If the content of the (meth)acrylic acid alkyl ester is less than 50% by weight, the tack etc. of the resulting pressure-sensitive adhesive composition will be reduced.

As the above (meth)acrylic acid alkyl ester, (
Methyl acrylate, ethyl (meth)acrylate,
Isopropyl (meth)acrylate.

(meth) n-propyl acrylate, (meth) isobutyl acrylate, (meth) aphryl-n-butyl, (meth) hexyl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) Octyl acrylate, nonyl (meth)acrylate,
Examples include isononyl (meth)acrylate and decyl (meth)acrylate.

Monomers that can be used in addition to (meth)acrylic acid alkyl esters include vinyl aromatic monomers such as styrene, α-methylstyrene, and vinyltoluene, (meth)acrylic acid, crotonic acid, cinnamic acid, Unsaturated carboxylic acids such as itaconic acid, fumaric acid and maleic acid; monoalkyl esters of unsaturated dicarboxylic acids such as itaconic acid monoethyl ester, fumaric acid monobutyl ester and maleic acid monobutyl ester; acrylonitrile, α-chloroacrylonitrile and Vinyl cyanide monomers such as methacrylonitrile; ethylenically unsaturated carboxylic acid amides and N-substituted compounds such as acrylamide, methacrylamide, and N-methylolacrylamide; unsaturated alcohols such as allyl alcohol; (meth)acrylic acid 2 - Functional alkyl esters of (meth)acrylic acid such as hydroxyethyl, 2-hydroxypropyl (meth)acrylate, and glycidyl methacrylate; Other examples include vinyl acetate, vinyl chloride, vinylidene chloride, and the like.

Among the above monomers, the amount of unsaturated monomers having a functional group such as a carboxyl group, hydroxyl group, amide group or epoxy group is 10% based on the total amount of all monomers constituting the copolymer. It is preferably less than 100% by weight, and more preferably 1 to 5% by weight.

When the amount of the functional unsaturated monomer used exceeds 10 to 10, the glass transition temperature of the resulting polymer increases, resulting in a decrease in the tack of the pressure-sensitive adhesive composition.

In addition to the above monomers, 5% by weight or less of a monomer having two or more polymerizable vinyl groups in one molecule, such as ethylene glycol dimethacrylate or diallyl phthalate, can also be used as a crosslinking monomer. . When the amount of the crosslinkable monomer used exceeds 5%, the crosslinking density in the copolymer becomes too high and the resulting pressure-sensitive adhesive composition loses its tackiness.

<Additives> Compounds used together with the copolymer in the present invention (
(referred to as an additive) is a compound having the following structural formula.

R-0-(CH2CH,0)n-H (where n is a positive number, and R is a hydrogen atom, an alkyl group having 7 or less carbon atoms, a phenyl group, a tolyl group, or a carbon number 7 In the above general formula, n, that is, the number of added moles of ethylene oxide units, is:
The specific additives shown below have a distribution, but the average value is preferably 2 to 40, more preferably 4 to 20. When the number of moles of ethylene oxide added exceeds 40, the holding power of the resulting pressure-sensitive adhesive composition decreases, and for example, in a pressure-sensitive adhesive tape using such a pressure-sensitive adhesive composition, the corrugated board sealability tends to deteriorate.

Specific examples of R in the above general formula include a hydrogen atom; an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and a heptyl group; a phenyl group, a p-methylphenyl group, an m- Methylphenyl group, 0-
Examples include tolyl groups such as methylphenyl; acyl groups such as formyl, acetyl, propionyl, and butyryl.

Examples of such compounds include polyethylene glycol (molecular weight 300) and PhG, which has 4 moles of ethylene oxide added to polyoxyethylene phenyl ether.
-40 (manufactured by Nippon Nyukazai ■).

product name) etc.

The desirable amount of the additive used is 0.000 parts per 100 weight parts of the total monomers constituting the acrylic ester copolymer.
001 to 10 parts by weight is preferable, more preferably 0.0
It is 2 to 2 parts by weight. If the amount is less than 0.001 parts by weight, no improvement in holding power or cardboard sealing performance will be observed;
This is because when the amount exceeds 1 part by weight, such effects reach a saturated state, and on the other hand, the adhesive strength decreases significantly, impairing the original function as an adhesive.

There are no particular restrictions on the timing of blending these additives; for example, when polymerizing a copolymer that is an acrylic ester adhesive, they may be mixed and dissolved in monomers,
Further, it may be added and mixed into the copolymer obtained by polymerization. Although it is naturally possible to use one type of additive, it is also possible to use two or more types in combination.

<Production of acrylic ester adhesive> Polymerization for producing the copolymer that is the acrylic ester adhesive of the present invention is carried out by conventionally known emulsion polymerization, solution polymerization, and suspension polymerization methods. If necessary, chain transfer agents and plasticizers may be added during polymerization, and after polymerization, thickeners, crosslinking agents, preservatives, rust preventives, pigments, plasticizers, and fillers may be added. .

Antifreeze agents, high boiling point solvents and antifoaming agents may also be added as appropriate.

(Adhesive sheet) The above-mentioned adhesive composition of the present invention is applied to the surface of a base material to provide an adhesive sheet. The base material is paper.

There are sheets of plastic such as polyethylene and polyester, and the adhesive composition is usually applied to the surface of the base material so that the thickness after drying is about 20 to 50 μm to form a layer of the adhesive composition. Ru. The adhesive sheet obtained in this way is adhesive tape.

Including adhesive labels, adhesive posters, etc.

[Examples and comparative examples]

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Parts on each side refer to parts by weight and percentages.
% means weight %. Adhesive force, holding force, tack, and cardboard sealability were each measured by the following methods.

<Adhesive strength> 50μ thick polyester film with a dry thickness of 25μ
Directly apply adhesive so that 100'CX 2
Dry for a minute to form an adhesive film. Regarding this, using a stainless steel plate as the adherend, following the JIS Z-0237 standard,
Measurement was performed according to the 180 degree peeling method.

<Holding Strength> An adhesive film similar to that used in the adhesive strength test was made and attached to a stainless steel plate in a size of 25 x 25 mm, and the time until it peeled off was measured by applying a load of 1 g at 80°C. When held for 3 hours, the deviation width was measured.

<Tack> Make an adhesive film similar to the adhesive strength test and JISZ-02
The measurement was carried out according to the ball rolling method of No. 37.

<Cardboard Sealing Properties> Kraft paper was coated with an adhesive so as to have a thickness of 40 μm after drying, and a craft tape with a width of 5 cm and a length of 50 cm was prepared. 30cm x 30cm x 30cm A double cardboard box with a K liner finish is sealed with craft tape at the double-door joints so that the length is 50111. Leave it for one week under an atmosphere of 23℃ x 65% RH8, then remove the craft tape. The number of pieces that were peeled off and the lid opened was counted. Since two cardboard boxes were used, there were a total of 8 319 fixed points.
It was a point.

Example 1 324 equipped with stirrer, thermometer, cooler, and dropping funnel
50 parts of water was placed in a flask and the temperature was raised to 80'C. 2-ethylhexyl acrylate (hereinafter referred to as rHAJ)
80 parts, 17 parts of n-butyl acrylate (hereinafter referred to as rBAJ) and PhG-40 (4 moles of ethylene oxide of polyethylene glycol phenyl ether)
After adding and dissolving 0.03 part of Nippon Nyukazai Kyusei (trade name),
2.8 parts of acrylic acid (hereinafter referred to as rAAJ), N-
0.2 part of methylol acrylamide (hereinafter referred to as rN-MAM) was mixed. To this mixture, 1.0 parts of sodium lauryl sulfate as an emulsifier was added together with 22 parts of water, and the resulting monohost emulsion was continuously added dropwise over 4 hours together with 15 parts of a 5% ammonium persulfate aqueous solution. Polymerization was carried out. After completion of the dropwise addition, the mixture was further aged at 80° C. for 2 hours and cooled to room temperature to obtain a copolymer emulsion with a viscosity of 240 cps, a solid content of 53.1%, and a pH of 2.0. The obtained emulsion was 1i: stable with almost no aggregates. This emulsion l.

PH by adding 10% ammonia water to 0 parts
1 part of a polycarboxylic acid type thickener (manufactured by Toagosei Kagaku Kogyo@, trade name B-300) prepared to have a viscosity of 7.0 was added to obtain an adhesive composition having a viscosity of 12.0 OO cps. The adhesive properties of this adhesive composition are shown in Table 1.

Example 2 The P h G-40 of Example 1 was replaced with polyethylene glycol having a molecular weight of 300, and the other conditions were the same, but the viscosity was 11.
, 500 cps was obtained.

Table 1 shows the adhesive properties of this adhesive composition.

Example 3 324 equipped with stirrer, thermometer, cooler, and dropping funnel
0 flask was charged with 80 parts of toluene, and the temperature was raised to 75°C. PhG-60 (manufactured by Nippon Nyukazai ■, trade name), which is 6 moles of ethylene oxide of polyoxyethylene phenyl ether added to 85 parts of BA and 10 parts of ethyl acrylate.
．． After adding 2 parts and dissolving, 5 parts of AA was mixed. This mixture and azobisisobutyronitrile (rA I B N
Polymerization was carried out by continuously adding dropwise over 4 hours together with 50 parts of a toluene solution in which 1.0 part (referred to as J) was dissolved.

After the addition, 0.3 parts of AIBN was added, and the mixture was aged at 75°C for 5 hours and cooled to room temperature, resulting in a viscosity of 3700 cps.
, a copolymer with a solid content of 43.4% was obtained. This copolymer 1
00 parts, Coronate L (manufactured by Nippon Polyurethane Industries @,
(trade name) was added to obtain an adhesive composition. The adhesive properties of this adhesive composition are shown in Table 1.

Examples 4 to 7 50 parts of HA, 40 parts of BA, 6 parts of vinyl acetate, and 4 parts of afrylumi were mixed and polymerized in the same manner as in Example 3 until the viscosity was 4+.
A copolymer of 100 cps and solid content of 43.0% was obtained. PhG-20 (Nippon Nyukazai@
0.005 part, 0.05 part, 0, 2 parts or 0.7 parts of Coronate L (trade name) and 1 part of Coronate L.

The adhesive properties of the adhesive composition after adding 2 parts and mixing are shown below.
Shown in 1.

Comparative Example 1 After emulsion polymerization was carried out in the same manner as in Example 1 except that the additive P h G-4 0 was not used, the obtained copolymer emulsion was similarly thickened to obtain an adhesive composition. Ta. The adhesive properties of this adhesive composition were as shown in Table-2.

Comparative Example 2 In an organic solvent solution of the copolymer obtained in Example 3,
A pressure-sensitive adhesive composition was obtained by adding 2 parts of Coronate L1 without adding the polyethylene glycol compound to be used in the present invention. The adhesive properties of this adhesive composition are shown in Table-
As shown in 2.

Comparative Examples 3 to 4 Ph
All examples were as in Example 1 except that the same amount as G-40 was added.
Emulsion polymerization was carried out in the same manner as above, and the resulting copolymer emulsion was further thickened to obtain an adhesive composition. The adhesive properties of this adhesive composition are also shown in Table-2.

(c) Effects of the Invention The adhesive of the present invention has excellent adhesive strength, cohesive force, and tack, and also has excellent corrugated sealing properties, so it can be used not only for adhesive tapes but also for adhesive sheets such as adhesive labels. It can also be used widely.

Claims (2)

[Claims] (1) Adhesive composition R-O-(CH_2CH_2O)_n-H (formula (wherein, n is a positive number, and R is a hydrogen atom, an alkyl group having 7 or less carbon atoms, a phenyl group, a tolyl group, or an acyl group having 4 or less carbon atoms.) (2) A pressure-sensitive adhesive sheet in which a layer of the pressure-sensitive adhesive composition according to claim 1 is formed on the surface of a base material.