JP6510567B2 - Acrylic emulsion pressure sensitive adhesive excellent in low temperature adhesion and holding power and method for producing the same - Google Patents

Description

  The present application claims the benefit of priority based on Korean Patent Application No. 2014-0104185 dated August 12, 2014, and the entire contents disclosed in the document of the Korean patent application are part of this specification. As included.

  The present invention relates to an acrylic emulsion pressure-sensitive adhesive excellent in low temperature adhesion and holding power, and a method for producing the same.

  Recently, the use of sticker-type facing materials such as interior / exterior materials, interior materials and advertising materials of buildings to which a pressure-sensitive adhesive has been applied has greatly increased. As the pressure-sensitive adhesive, the existing oil-based pressure-sensitive adhesive is discharged into the air for a long period of time after construction, so that headaches, eye and nose irritations, coughing on people living inside the building It causes symptoms such as itching, dizziness, fatigue, and loss of concentration, and causes problems with Sick House Syndrome that cause respiratory disease, heart disease, cancer etc. upon prolonged exposure.

  For these reasons, the use of water as a dispersion medium has increased interest in an aqueous emulsion adhesive that is environmentally friendly and does not cause the discharge of substances harmful to the human body, and is rapidly replacing it. As the aqueous emulsion pressure-sensitive adhesive is independent of the viscosity of the pressure-sensitive adhesive and the molecular weight of the dispersion polymer, a polymer having a high molecular weight can be used as compared to a solvent-based polymer, and a wide concentration range of solid content can be obtained. It has the advantages of low resistance to aging, low viscosity, good adhesion in the low solids region, and good compatibility with other polymers.

  However, since water is used as a solvent, the drying speed is slow, the adhesion to the hydrophobic adhesive surface and the non-porous adhesion agent is low, the selection range of the curing agent is narrow, and the initial adhesion decreases. In addition to having it, since it contains an emulsifier and a dispersing agent, water resistance is low, and it has problems, such as not being able to reach physical properties like an oil-based adhesive.

  On the other hand, pressure sensitive adhesives (PSA) generally have excellent initial tackiness, cohesion and cohesion, good balance among them, and are subject to peeling off for removal after long-term adhesion. Characteristics such as not causing surface damage and contamination of the adherend are required.

  Recently, with the diversification of the use environment of the pressure-sensitive adhesive, the demand for pressure-sensitive adhesives excellent in low-temperature adhesive strength and holding power is increasing in addition to the general adhesive physical properties described above. For example, environmental friendly hybrid cars have attracted much interest in connection with environmental issues, and adhesives used in batteries built into hybrid cars have acceptable levels of adhesion even in harsh environments. And must be able to ensure holding power.

  The prior art has solved the initial cohesion, cohesion and cohesion of aqueous emulsion adhesives to a certain extent, but at the same time has not provided adhesives with excellent low temperature cohesion and retention.

  Therefore, there is a great need for an adhesive that is excellent in low temperature adhesion and retention while being environmentally friendly.

  The present invention aims to solve the problems of the prior art as described above and the technical problems demanded from the past.

  As a result of intensive research and various experiments, the inventors of the present application have found that the acrylic emulsion pressure-sensitive adhesive has 0.6 to 1.5% by weight of unsaturated carboxylic acid monomer based on the total weight of the mixture. And when it contains 2.5 to 10 weight% of a hydroxyethyl acrylate monomer, it discovered that low temperature adhesiveness and retention improved, and came to complete this invention.

  Therefore, the acrylic emulsion adhesive according to the present invention comprises i) (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile Iii) one or more monomers selected from the group consisting of unsaturated carboxylic acids, iv) crosslinkers, and v) hydroxyethyl acrylate monomers Comprising an acrylic emulsion resin produced by the polymerization of a mixture comprising at least one monomer selected from the group consisting of iii) unsaturated carboxylic acids, based on the total weight of the mixture. .6 to 1.5% by weight, and v) 2.5 to 10% by weight of hydroxyethyl acrylate monomer.

  As used herein, the term "mixture" may be prepared based on an acrylic monomer, and may be introduced in the form of a mixture of a monomer, a crosslinking agent, etc. described below. It includes a variety such as the monomer and the crosslinking agent may be sequentially introduced and manufactured.

  The one or more monomers selected from the group consisting of unsaturated carboxylic acids of iii) may be contained in an amount of 0.8 to 1.3% by weight based on the total weight of the mixture, particularly 0 It may be contained in an amount of 9 to 1.2% by weight.

  The hydroxyethyl acrylate monomer of v) may be included in an amount of 2.5 to 8 wt%, specifically 2.5 to 6 wt%, based on the total weight of the mixture.

  Thus, when an appropriate amount of unsaturated carboxylic acid monomer and hydroxyethyl acrylate monomer is contained, there is an effect that the low temperature adhesive strength and the holding power are increased, and in particular, such an effect is a single amount of hydroxyethyl acrylate Increase in intermolecular attraction via hydrogen bonding and dipolar-dipole attraction etc. of hydroxyl groups present in the body, and self cross-linking of hydroxyl group and hydroxyl group or hydroxyl group and polar functional group in polymer (self cross) Presumably due to the increase in cohesion through linking.

  When the content of the hydroxyethyl acrylate monomer is out of the above range and less than 2.5% by weight, the self-crosslinking is hardly formed in the polymer, so the retention is greatly reduced, and in the case of exceeding 10% by weight Since the self-crosslinking is excessively formed in the polymer and the pressure-sensitive adhesive becomes harder than necessary, the attractive force with the pressure-sensitive adhesive becomes relatively weak and the low temperature adhesion is decreased. There is a problem that the effect can not be obtained.

  Further, as with the polar monomer hydroxyethyl acrylate, the reactivity with the polar monomer unsaturated carboxylic acid greatly affects the physical properties. In particular, it has a great influence on the degree of crosslinking and the stability of the adhesive, which is presumed to be due to the strong interaction between polar monomers.

  When the content of the unsaturated carboxylic acid monomer is out of the above range and less than 0.6% by weight, the initial low temperature adhesion, the initial adhesion and the holding power to the polar substrate glass are reduced, If it exceeds 5% by weight, the cross-linking in the polymer becomes strong and the glass transition temperature rises, and as a result, the coercivity can be partially increased for this reason, but the initial cohesion at low temperature is largely There is a problem of falling.

  In one embodiment, the acrylic emulsion pressure-sensitive adhesive may have an initial low temperature adhesion of 12 N / inch or more, and the test method FINAT TEST METHOD NO. In the retention test based on 8, the adhesion time of the adhesive sample of the acrylic emulsion adhesive to the surface of the stainless steel (SUS 304) may be 100 minutes or more, details of the initial low temperature adhesion and retention Will be described later.

  Hereinafter, the acrylic emulsion pressure sensitive adhesive concerning the present invention is explained in detail.

  In one embodiment, the monomer of i) is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl acrylate, t-butyl Group consisting of methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, 2-ethylhexyl (meth) acrylate, isodecyl acrylate, decyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, and lauryl (meth) acrylate It may be one or more selected from, particularly 60 to 90% by weight based on the total weight of the mixture.

  The monomer of i) may be contained in an amount of 60 to 90% by weight based on the total weight of the emulsion resin, as described above. When the content is less than 60% by weight, the initial adhesion of the acrylic emulsion pressure-sensitive adhesive can not be secured, and when it is contained more than 90% by weight, the pressure-sensitive adhesive on the adherend at the time of removal after use. It is not preferable because large transfer occurs.

  Moreover, carbon number of the alkyl group of said i) may be 1-14 in detail, and, more specifically, may be 2-14. When the number is less than one, the cohesion of the acrylic emulsion pressure-sensitive adhesive is lowered, and when it is more than 14, the acrylic emulsion pressure-sensitive adhesive becomes too soft and the adhesion property is lowered, which is not preferable.

  In one embodiment, the monomer ii) is one or more selected from the group consisting of vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, acrylonitrile and methacrylonitrile. It may also be, in particular, vinyl acetate, vinyl butanoate or acrylonitrile.

  The monomer ii) may be contained in an amount of 1 to 35 wt%, specifically 7 to 25 wt%, based on the total weight of the mixture. When the content is less than 1% by weight, the acrylic emulsion pressure-sensitive adhesive becomes too soft to secure sufficient adhesion properties, and when the content is more than 35% by weight, the acrylic emulsion pressure-sensitive adhesive Is not preferable because it becomes too hard and a significant decrease in adhesion occurs.

  In one embodiment, the monomer of iii) is one or more selected from the group consisting of acrylic acid, itaconic acid, maleic anhydride, fumaric acid, crotonic acid, methacrylic acid, and ethyl methacrylic acid. It may also be acrylic acid, in particular.

  The monomer of iii) may be contained in an amount of 0.6 to 1.5% by weight based on the total weight of the mixture. If the content is less than 0.6% by weight, the acrylic emulsion pressure-sensitive adhesive becomes too soft to ensure sufficient adhesion properties, and if it is contained in excess of 1.5% by weight, the acrylic is included. It is not preferable because the emulsion adhesive becomes too hard to cause a marked decrease in adhesion.

  In one embodiment, the crosslinking agent of the vi) for reinforcing the cohesion may be contained in an amount of 0.1 to 3% by weight based on the total weight of the mixture, and within the above range, the acrylic emulsion adhesive Have sufficient cohesion.

  The crosslinking agent is added to reinforce cohesion, and in one embodiment, may be a compound containing 5 to 15 alkylene oxide groups and having an acrylate group or a vinyl group. In detail, it may be a compound containing 6 to 12 alkylene oxide groups and having an acrylate group or a vinyl group, and within the above-mentioned range, there is an effect that both normal temperature and aged adhesiveness, and stability are excellent.

  For reference, the number of alkylene oxide groups means the average number of alkylene oxide groups contained in the used crosslinking agent, and if the number of the alkylene oxide groups is less than 5 in the crosslinking agent, adhesion produced The agent becomes hard more than necessary to reduce initial tack, and when the number of alkylene oxide groups is more than 15, the produced adhesive becomes too soft to reduce adhesion properties, which is not preferable.

  In one embodiment, the crosslinking agent is an organic crosslinking agent such as polyethylene glycol diacrylate, polypropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylpropane triacrylate, tripropylene glycol Diacrylate, 1,3-butanediol diacrylate, pentaerythritol triacrylate, 3-trimethoxysilylpropyl methacrylate, vinyltrimethoxysilane, divinylbenzene, etc., and inorganic crosslinkers aluminum acetylacetonate, zinc acetate, zirconium carbonate And the like, and may be one or more selected from the group consisting of It may be one or more selected from the group consisting of diacrylates.

  On the other hand, in one embodiment, the mixture may further contain an epoxy group-containing unsaturated monomer, and the epoxy group-containing unsaturated monomer may be, in detail, glycidyl (meth) acrylate, α- It may be one or more selected from the group consisting of methyl glycidyl (meth) acrylate, allyl glycidyl ether, oxocyclohexyl (meth) acrylate, 3,4-epoxycyclohexyl methyl (meth) acrylate, and more specifically, It may be glycidyl (meth) acrylate or allyl glycidyl ether.

  The epoxy group-containing unsaturated monomer may be contained in an amount of 0.1 to 3% by weight based on the total weight of the mixture, and within the above range, the pressure-sensitive adhesive composition has sufficient cohesion.

  The present invention also discloses a method of producing the acrylic emulsion pressure-sensitive adhesive.

  The method for producing the acrylic emulsion pressure-sensitive adhesive is not particularly limited in the case of the emulsion polymerization, but a monomer addition method or a seed polymerization method in which control of the heat of reaction is easy can be used.

  Specifically, the method for producing the acrylic emulsion pressure-sensitive adhesive is

  (A) i) (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) one or more selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile Of one or more monomers selected from the group consisting of: iii) unsaturated carboxylic acids, based on the total weight of the mixture, 0.6 to 1.5% by weight, iv) crosslinkers, and v B.) Producing a mixture containing 2.5 to 10 wt.% Of hydroxyethyl acrylate monomer based on the total weight of the mixture;

  (B) A process of preparing an emulsion by adding a surfactant, an electrolyte and water to the mixture;

  (C) A process of emulsion polymerization after adding an initiator to the emulsion;

  It is characterized by including.

  The method for producing the acrylic emulsion pressure-sensitive adhesive is

  (D) The method may further include adding an acidity (pH) regulator to the acrylic emulsion adhesive to adjust the acidity of the acrylic emulsion adhesive to 6 to 9.

  The surfactant (B) is used for initial particle formation during the emulsion polymerization, control of the size of the produced particles, and stability of the particles, and is composed of a hydrophilic group and a lipophilic group. And may be divided into anionic, cationic and nonionic surfactants. An anionic and non-ionic surfactant may be mainly used, and they may be mixed with each other to complement mechanical stability and chemical stability.

  Such surfactant may be an anionic surfactant and / or a nonionic surfactant, specifically, the anionic surfactant may be sodium alkyl diphenyl oxide disulfonate, sodium polyoxyethylene alkyl The surfactant may be one or more selected from the group consisting of ether sulfate, sodium polyoxyethylene lauryl ether sulfate, and sodium dialkyl sulfosuccinate, and the nonionic surfactant is polyethylene oxide alkyl aryl ether, polyethylene oxide It may be one or more selected from the group consisting of alkylamines and polyethylene oxide alkyl esters.

  The electrolyte used in the polymerization reaction is to adjust the pH to impart stability to the polymerized acrylic emulsion resin, and specifically, sodium bicarbonate, sodium carbonate, sodium phosphate, It may be one or more selected from the group consisting of sodium sulfate, sodium chloride and the like, and may be sodium carbonate in detail, 0.1 to 2 parts by weight based on 100 parts by weight of the mixture It may be in parts, in particular 0.3 to 1 part by weight.

  In one embodiment, the initiator is a water soluble initiator and may be a water soluble initiator such as ammonium or alkali metal persulfate, hydrogen peroxide, peroxide, hydroperoxide, etc. Can be used together with one or more reducing agents to carry out the emulsion polymerization reaction. The reducing agent may be sodium bisulfite, sodium metabisulfite, sodium hydrosulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid and the like.

  The temperature of the emulsion polymerization reaction may be specifically 0 to 100 ° C., more specifically 40 to 90 ° C., the initiator alone, or the initiator and the reducing agent. It can adjust by the method of mixing and using one or more types among them.

  An acidity (pH) regulator may be added to the acrylic emulsion adhesive to adjust the acidity, wherein the acidity of the acrylic emulsion adhesive may be adjusted to 6 to 9, in detail. More specifically, the acidity regulator may be adjusted to 7 to 8, and the acidity regulator is an alkaline substance, such as a monovalent metal or divalent metal hydroxide, an inorganic substance such as a chloride or carbonate, ammonia or an organic substance. It may be an amine or the like.

  Furthermore, the acrylic emulsion adhesive according to the present invention comprises a thickener and a wetting agent in order to prevent the shrinkage phenomenon of the acrylic emulsion adhesive that occurs when coating on the surface of silicone release paper. It can further include.

  The thickener may be CMC (Carboxyl Methyl Cellulose), acrylic sol, polyvinyl alcohol, starch, alginate, dextrin or the like, and in particular, polyvinyl alcohol.

  The wetting agent is to change the hydrophilic pressure-sensitive adhesive to be hydrophobic so that the pressure-sensitive adhesive adheres well to the surface of the hydrophobic silicone release paper, and usually a surfactant mixture is used. And may further include glycol or alcohol.

  The present invention also provides a pressure-sensitive adhesive sheet in which an acrylic emulsion pressure-sensitive adhesive is applied on a pressure-sensitive adhesive film or sheet to form a pressure-sensitive adhesive layer.

  The pressure-sensitive adhesive sheet may be a building interior / exterior material, an interior material, an advertising film, or an adhesive film or sheet of a label, and the pressure-sensitive adhesive layer has a thickness of 10 to 100 μm, specifically 20 to 30 μm. Because it is excellent in coating properties, it has sufficient adhesion properties.

  Hereinafter, the present invention will be described with reference to examples of the present invention, but the following examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1
In a 2 L glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 175 g of water and 1 g of 30% sodium polyoxyethylene alkyl ether sulfate are charged, and the reactor is stirred. The interior of the was replaced with nitrogen, and the temperature was raised to 80.degree. C. under a nitrogen atmosphere and maintained for 60 minutes.

  Separately, for preparation of a pre-emulsion, in a beaker were added 645 g of 2-ethylhexyl acrylate, 20 g of hydroxyethyl acrylate, 15 g of vinyl acetate, 15 g of metamethyl acrylate, 8 g of acrylic acid, 1 g of polyethylene glycol diacrylate, and n-dodecyl mercaptan 0. After charging 3 g, it was mixed for 30 minutes to produce a mixture.

  Into the above mixture, 13 g of 30% sodium polyoxyethylene alkyl ether sulfate, 7 g of 50% alkyl diphenyl oxide disulfonate, 2 g of sodium carbonate, 2 g of sodium methyl allyl sulfonate and 175 g of water are added and stirred for 10 minutes with a stirrer. A cloudy emulsion was prepared.

  In the glass reactor, 3.5 g of a 10% ammonium persulfate solution was charged and dissolved by stirring for 10 minutes.

  The emulsion and 90 g of a 10% ammonium persulfate solution were continuously and uniformly charged into the glass reactor for 4 hours. Thereafter, 2 g of a 10% ammonium persulfate solution was further added, the temperature was raised to 80 ° C. for 30 minutes, and this temperature was maintained for 1 hour, and then cooled to room temperature to produce an acrylic emulsion adhesive .

  The pH was adjusted to 7 to 8 by adding 28% aqueous ammonia solution to the acrylic emulsion pressure-sensitive adhesive.

Example 2
An acrylic emulsion pressure-sensitive adhesive was produced in the same manner as in Example 1 except that 40 g of hydroxyethyl acrylate was added at the time of production of the pre-emulsion.

Example 3
An acrylic emulsion adhesive was manufactured in the same manner as in Example 1 except that 55 g of hydroxyethyl acrylate was added at the time of preparation of the pre-emulsion.

Example 4
An acrylic emulsion pressure-sensitive adhesive was manufactured in the same manner as in Example 1 except that 70 g of hydroxyethyl acrylate was added at the time of preparation of the pre-emulsion.

Comparative Example 1
An acrylic emulsion adhesive was manufactured in the same manner as in Example 1 except that hydroxyethyl acrylate was not added at the time of preparation of the pre-emulsion.

Comparative Example 2
An acrylic emulsion pressure-sensitive adhesive was produced in the same manner as in Example 1 except that 15 g of hydroxyethyl acrylate was added at the time of production of the pre-emulsion.

Comparative Example 3
An acrylic emulsion pressure-sensitive adhesive was produced in the same manner as in Example 1 except that 90 g of hydroxyethyl acrylate was added at the time of production of the pre-emulsion.

Comparative Example 4
An acrylic emulsion pressure-sensitive adhesive was manufactured in the same manner as in Example 1 except that 110 g of hydroxyethyl acrylate was added at the time of preparation of the pre-emulsion.

Comparative Example 5
An acrylic emulsion adhesive was manufactured in the same manner as in Example 1 except that 4 g of acrylic acid was added at the time of preparation of the pre-emulsion.

Comparative Example 6
An acrylic emulsion adhesive was manufactured in the same manner as in Example 1 except that 12 g of acrylic acid was added at the time of preparation of the pre-emulsion.

Comparative Example 7
An acrylic emulsion adhesive was manufactured in the same manner as in Example 2 except that 4 g of acrylic acid was added at the time of preparation of the pre-emulsion.

Comparative Example 8
An acrylic emulsion adhesive was manufactured in the same manner as in Example 3 except that 4 g of acrylic acid was added at the time of preparation of the pre-emulsion.

Comparative Example 9
An acrylic emulsion adhesive was manufactured in the same manner as in Example 4 except that 4 g of acrylic acid was added at the time of preparation of the pre-emulsion.

Comparative Example 10
An acrylic emulsion adhesive was manufactured in the same manner as in Example 4 except that 12 g of acrylic acid was added at the time of preparation of the pre-emulsion.

Experimental Example 1
Pressure-sensitive adhesive coated with pressure-sensitive adhesive The pressure-sensitive adhesive prepared in Examples 1 to 4 and Comparative Examples 1 to 3 is coated on a 39 μm PET film and dried in an oven at 120 ° C. for 1 minute to form an adhesive layer. Have a thickness of 20 μm. After the thickness was measured, it was cut into a size of 1 inch x 200 mm to produce an adhesive sample.

  The adhesion properties of the pressure-sensitive adhesives produced from Examples 1 to 4 and Comparative Examples 1 to 3 were tested by the following method, and the results are shown in Table 1 below.

* Initial low temperature adhesion test : Test method FINAT TEST METHOD NO. In accordance with 9, an adhesive strip of an acrylic emulsion pressure-sensitive adhesive is annularly produced in a chamber at -10 ° C and left to stand for 10 minutes, and then affixed to the surface of the glass without applying pressure. After 5 seconds, it was measured while peeling at a speed of 300 mm / min using a TA Texture Analyzer instrument.

* Retention test : Test method FINAT TEST METHOD NO. In accordance with No. 8, after adhering the adhesive sample of acrylic emulsion adhesive to the surface of stainless steel (SUS 304) so that the adhesion surface is 1 inch x 1 inch, hang a 1 kg weight on the tip of the sheet, and the weight The time to fall was measured.

* Initial adhesion test : Test method FINAT TEST METHOD NO. In accordance with No.9, an adhesive strip of acrylic emulsion adhesive is prepared in an annular shape and attached to the surface of glass without applying pressure, and after 5 seconds, it is made at a speed of 300 mm / min using a TA Texture Analyzer device. It measured, peeling.

* Peel force test : Test method FINAT TEST METHOD NO. In accordance with 2, an adhesive sample of an acrylic emulsion adhesive is attached to a glass plate by reciprocating a 2 kg roller twice at a speed of 300 mm / min, and after aging for 20 minutes at room temperature, TA (TA Measurement was carried out using a Texture Analyzer) at a speed of 300 mm / min while peeling at 90 degrees.

  Referring to Table 1, the acrylic emulsion adhesive of Examples 1 to 4 has an initial low temperature adhesive strength due to the action of an acrylic acid monomer which is an unsaturated carboxylic acid and an hydroxyethyl acrylate monomer in a polymer. While it can be confirmed that the retention strength has been improved, the acrylic emulsion adhesive of Comparative Examples 1 to 10 does not contain an adequate amount of acrylic acid monomer or hydroxyethyl acrylate monomer, so the initial low temperature adhesion is observed. It can be confirmed that the force or holding force is not sufficient.

  Specifically, referring to Examples 1 to 4 and Comparative Examples 1 to 4, the content of acrylic acid is about 1 to 1.2% by weight, while the content of hydroxyethyl acrylate is 0 to 4. It is distributed differently among 14% by weight. In Comparative Example 1 and Comparative Example 2, when the content of hydroxyethyl acrylate is less than 2.5% by weight at the boundary, the retentivity is significantly reduced, and through Comparative Example 3 and Comparative Example 4, hydroxyethyl acrylate is reduced. It can be seen that when the content of 10% by weight is contained more than that at the boundary, the holding power is increased but the initial low temperature adhesion is significantly reduced.

  Thus, it can be seen that the initial low temperature tack and retention is significantly increased when the proper amount of acrylic acid is included and 2.5 to 10 wt% of hydroxyethyl acrylate is included.

  Referring to Examples 1 to 4 and Comparative Examples 5 to 10, all of these Examples and Comparative Examples contain an appropriate amount of hydroxyethyl acrylate at 2.5 to 10% by weight, while acrylic acid is 0. It contains variously between 0.5 and 1.7% by weight. Comparing Example 1 with Comparative Examples 5 and 6 or Example 4 with Comparative Examples 9 and 10, when the content of acrylic acid is less than 0.6% by weight, the retentivity is largely reduced, and 1.5 weight When it exceeds%, it is understood that the initial low temperature adhesion is greatly reduced. When comparing Examples 2 and 3 with Comparative Examples 7 and 8, it is possible to confirm that the initial low temperature adhesion or holding power is not sufficient when acrylic acid is contained at less than 0.6% by weight.

  Through this, it can be seen that the initial low temperature tack and holding power are significantly increased when the proper amount of hydroxyethyl acrylate is included and the acrylic acid is included at 0.6 to 1.5% by weight.

  Such a result is presumed to be that the polar functional groups of hydroxyethyl acrylate and acrylic acid interact strongly in the pressure-sensitive adhesive, and even a minute difference greatly affects the physical properties of the pressure-sensitive adhesive.

  In conclusion, in the case of acrylic emulsion adhesives comprising 0.6 to 1.5% by weight unsaturated carboxylic acid and 2.5 to 10% by weight hydroxyethyl acrylate monomer, based on the total weight of the mixture: It can be confirmed that the low temperature adhesive strength and the holding power are significantly increased while the general adhesive physical properties are not lowered.

  Those skilled in the art to which the present invention belongs can make various applications and modifications within the scope of the present invention based on the above contents.

  As explained above, according to the present invention, the acrylic emulsion adhesive comprises 0.6 to 1.5% by weight of unsaturated carboxylic acid monomer and hydroxyethyl acrylate unit based on the total weight of the mixture. When the body is contained in an amount of 2.5 to 10% by weight, the low temperature adhesion and holding power are remarkably improved.

Claims (20)

i) (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) at least one unitary quantity selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile Iii) an acrylic emulsion resin produced by the polymerization of a mixture comprising one or more monomers selected from the group consisting of unsaturated carboxylic acids, iv) crosslinkers, and v) hydroxyethyl acrylate monomers Including
Said mixture is based on the total weight of the mixture, ii) 1 to 35% by weight of one or more monomers selected from the group consisting of allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles, iii) unsaturated 0.6-1.5 wt% of one or more monomers selected from the group consisting of saturated carboxylic acids, and v) 2.5 to 10 wt% observed containing a hydroxyethyl acrylate monomer,
Test method FINAT TEST METHOD NO. According to No.9, after making a cyclic adhesive sample of acrylic emulsion adhesive in a chamber at -10 ° C and leaving it to stand for 10 minutes, it is stuck on the surface of glass without applying pressure, and after 5 seconds, TA The initial low temperature adhesion measured while peeling at a speed of 300 mm / min using the Texture Analyzer device is 12 N / inch or more,
Test method FINAT TEST METHOD NO. In accordance with No. 8, after adhering the adhesive sample of acrylic emulsion adhesive to the surface of stainless steel (SUS 304) so that the adhesion surface is 1 inch x 1 inch, hang a 1 kg weight on the tip of the sheet, An acrylic emulsion pressure-sensitive adhesive characterized in that an adhesion time to a holding power test in which falling time is measured is 100 min or more .   The acrylic emulsion resin comprises, based on the total weight of the mixture, i) 60 to 90% by weight of (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) allyl ester, vinyl ester, 1 to 35% by weight of one or more monomers selected from the group consisting of unsaturated acetate and unsaturated nitrile, iii) One or more monomers selected from the group consisting of unsaturated carboxylic acids 0.6 The method according to claim 1, characterized in that it is polymerized to .about.1.5% by weight, iv) 0.1 to 3% by weight of crosslinker, and v) 2.5 to 10% by weight of hydroxyethyl acrylate monomer. The acrylic emulsion adhesive described in 4.   The acrylic emulsion pressure sensitive adhesive according to claim 1, wherein the hydroxyethyl acrylate monomer of v) is contained in an amount of 2.5 to 8 wt% based on the total weight of the mixture.   The acrylic emulsion pressure sensitive adhesive according to claim 2, wherein the hydroxyethyl acrylate monomer is contained in an amount of 2.5 to 6 wt% based on the total weight of the mixture.   The monomer of i) is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl acrylate, t-butyl methacrylate, pentyl methacrylate, Hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, 2-ethylhexyl (meth) acrylate, isodecyl acrylate, decyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, and lauryl (meth) acrylate 1 The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive adhesive is at least one.   The monomer ii) is one or more selected from the group consisting of vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, acrylonitrile and methacrylonitrile. The acrylic emulsion adhesive according to claim 1.   The monomer of iii) is one or more selected from the group consisting of acrylic acid, itaconic acid, maleic anhydride, fumaric acid, crotonic acid, methacrylic acid, and ethyl methacrylic acid. The acrylic emulsion adhesive according to claim 1.   The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein the crosslinking agent of iv) is a compound having 5 to 15 alkylene oxide groups and having an acrylate group or a vinyl group. The acrylic emulsion pressure-sensitive adhesive according to claim 8 , wherein the crosslinking agent is one or more selected from the group consisting of polyethylene glycol diacrylate and polypropylene glycol diacrylate.   The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein the mixture further comprises an epoxy group-containing unsaturated monomer. The acrylic emulsion pressure sensitive adhesive according to claim 10 , wherein the epoxy group-containing unsaturated monomer is contained in an amount of 0.1 to 3 wt% based on the total weight of the mixture. The acrylic emulsion pressure-sensitive adhesive according to claim 10 , wherein the epoxy group-containing unsaturated monomer is glycidyl (meth) acrylate or allyl glycidyl ether. A method for producing the acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein
(A) i) (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) one or more selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile Of one or more monomers selected from the group consisting of: iii) unsaturated carboxylic acids, based on the total weight of the mixture, 0.6 to 1.5% by weight, iv) crosslinkers, and v B.) Producing a mixture comprising 2.5 to 10% by weight of hydroxyethyl acrylate monomer based on the total weight of the mixture;
(B) preparing an emulsion by adding a surfactant, an electrolyte, and water to the mixture;
(C) A method for producing an acrylic emulsion pressure-sensitive adhesive, comprising the step of adding an initiator to the emulsion and then performing emulsion polymerization. The manufacturing method is
(D) A process further comprising the step of adding an acidity (pH) regulator to the acrylic emulsion adhesive synthesized by the above-mentioned emulsion polymerization to adjust the acidity of the acrylic emulsion adhesive to 6 to 9, The manufacturing method of the acryl-type emulsion adhesive of Claim 13 . The method of producing an acrylic emulsion pressure-sensitive adhesive according to claim 13 , wherein the surfactant (B) is an anionic surfactant and / or a nonionic surfactant. The anionic surfactant is one or more selected from the group consisting of sodium alkyl diphenyl oxide disulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, and sodium dialkyl sulfosuccinate The method for producing an acrylic emulsion pressure-sensitive adhesive according to claim 15 , characterized in that 16. The acrylic according to claim 15 , wherein the nonionic surfactant is one or more selected from the group consisting of polyethylene oxide alkyl aryl ether, polyethylene oxide alkyl amine, and polyethylene oxide alkyl ester. Method of producing emulsion pressure sensitive adhesive. The electrolyte of the (B) is sodium bicarbonate, sodium carbonate, sodium phosphate, characterized in that one or more selected from the group consisting of sodium sulphate and sodium chloride, to claim 13 The manufacturing method of the acrylic type emulsion adhesive as described. The initiator according to claim 13 , wherein the initiator (C) is at least one selected from the group consisting of ammonium or alkali metal persulfates, hydrogen peroxide, peroxides, and hydroperoxides. Method of producing an acrylic emulsion pressure-sensitive adhesive.   A pressure-sensitive adhesive sheet, wherein the acrylic emulsion pressure-sensitive adhesive according to claim 1 is applied onto a pressure-sensitive adhesive film or sheet to form a pressure-sensitive adhesive layer.