JP6345969B2 - Manufacturing method of adhesive tape - Google Patents

Description

  The present invention relates to an emulsion containing a (meth) acrylate copolymer having a long-chain alkyl group and a method for producing the emulsion.

  A (meth) acrylate copolymer having a long-chain alkyl group is known as a side-chain crystalline polymer (see, for example, Patent Document 1). The side-chain crystalline polymer contains (meth) acrylate having a linear alkyl group having 16 or more carbon atoms as a long-chain alkyl group as a monomer component, and has a melting point due to the long-chain alkyl group. The side-chain crystalline polymer exhibits fluidity when it is heated to a temperature higher than this melting point and develops adhesiveness, and crystallizes when it is cooled to a temperature lower than the melting point, resulting in a decrease in adhesive strength. Therefore, it is used for adhesive applications.

  By the way, the conventional side chain crystalline polymer as described in Patent Document 1 is manufactured by a solution polymerization method. In view of environmental impact and safety, it is desirable to make the side chain crystalline polymer aqueous. The present applicant has previously developed an aqueous emulsion of a side chain crystalline polymer as described in Patent Document 2. As such an emulsion, one that is easy to manufacture and that has excellent adhesive properties in the usage form such as an adhesive tape is desirable.

JP-A-9-251923 JP 2012-172063 A

  An object of the present invention is to provide a long-chain (meth) acrylate emulsion that is easy to produce and has excellent adhesive properties and a method for producing the same.

［式中、Ｒ₁はアルキル基を示す。ｎは１〜４０の整数を示す。］
（３）前記エチレン性不飽和基を有する反応性アニオン系界面活性剤の添加量が、モノマー混合物１００重量部に対して固形分換算で１〜４０重量部である、前記（１）または（２）に記載の長鎖（メタ）アクリレート系エマルション。
（４）前記エチレン性不飽和基を有する反応性アニオン系界面活性剤の添加量が、モノマー混合物１００重量部に対して固形分換算で３〜３０重量部である、前記（１）〜（３）のいずれかに記載の長鎖（メタ）アクリレート系エマルション。
（５）前記エチレン性不飽和基を有する反応性アニオン系界面活性剤の添加量が、モノマー混合物１００重量部に対して固形分換算で１０〜３０重量部である、前記（１）〜（４）のいずれかに記載の長鎖（メタ）アクリレート系エマルション。
（６）保護コロイドを含有していない、前記（１）〜（５）のいずれかに記載の長鎖（メタ）アクリレート系エマルション。
（７）前記水性媒体が、水である、前記（１）〜（６）のいずれかに記載の長鎖（メタ）アクリレート系エマルション。
（８）固形分濃度が、２０〜６０重量％である、前記（１）〜（７）のいずれかに記載の長鎖（メタ）アクリレート系エマルション。
（９）固形分濃度が、３５〜５０重量％である、前記（１）〜（８）のいずれかに記載の長鎖（メタ）アクリレート系エマルション。
（１０）炭素数１６以上の直鎖状アルキル基を有する（メタ）アクリレート、炭素数１〜８のアルキル基を有する（メタ）アクリレートおよび極性モノマーを含むモノマー混合物を、界面活性剤が添加されている水性媒体中に分散させて分散液を得る工程と、前記分散液に重合開始剤を添加し、前記モノマー混合物の乳化重合を行う工程と、を含み、前記界面活性剤が、エチレン性不飽和基を有する反応性アニオン系界面活性剤である、長鎖（メタ）アクリレート系エマルションの製造方法。
（１１）前記モノマー混合物を攪拌手段によって攪拌状態とし、攪拌状態の前記モノマー混合物に前記界面活性剤が添加されている水性媒体を添加して前記分散液を得る、前記（１０）に記載の長鎖（メタ）アクリレート系エマルションの製造方法。
（１２）前記（１）〜（９）のいずれかに記載の長鎖（メタ）アクリレート系エマルションを乾燥処理することによって得られる粘着剤層が、フィルム状の基材の片面または両面に積層された、粘着テープ。 As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a solution means having the following constitution and have completed the present invention.
(1) A surfactant is added to a monomer mixture containing a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, a (meth) acrylate having an alkyl group having 1 to 8 carbon atoms, and a polar monomer. A long-chain (meth) acrylate emulsion containing a copolymer obtained by emulsion polymerization in an aqueous medium, wherein the surfactant is a reactive anionic surfactant having an ethylenically unsaturated group A long chain (meth) acrylate emulsion.
(2) The long-chain (meth) acrylate emulsion according to (1), wherein the reactive anionic surfactant having an ethylenically unsaturated group is a compound represented by the following general formula (I).

[Wherein R ₁ represents an alkyl group. n shows the integer of 1-40. ]
(3) The said (1) or (2) whose addition amount of the reactive anionic surfactant which has the said ethylenically unsaturated group is 1-40 weight part in conversion of solid content with respect to 100 weight part of monomer mixtures. ) Long chain (meth) acrylate emulsion.
(4) Said (1)-(3) whose addition amount of the reactive anionic surfactant which has the said ethylenically unsaturated group is 3-30 weight part in conversion of solid content with respect to 100 weight part of monomer mixtures. ) Long-chain (meth) acrylate emulsion according to any of the above.
(5) Said (1)-(4) whose addition amount of the reactive anionic surfactant which has the said ethylenically unsaturated group is 10-30 weight part in conversion of solid content with respect to 100 weight part of monomer mixtures. ) Long-chain (meth) acrylate emulsion according to any of the above.
(6) The long chain (meth) acrylate emulsion according to any one of (1) to (5), which does not contain a protective colloid.
(7) The long chain (meth) acrylate emulsion according to any one of (1) to (6), wherein the aqueous medium is water.
(8) The long chain (meth) acrylate emulsion according to any one of (1) to (7), wherein the solid content concentration is 20 to 60% by weight.
(9) The long chain (meth) acrylate emulsion according to any one of (1) to (8), wherein the solid content concentration is 35 to 50% by weight.
(10) A surfactant is added to a monomer mixture containing a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, a (meth) acrylate having an alkyl group having 1 to 8 carbon atoms, and a polar monomer. A step of obtaining a dispersion by dispersing in an aqueous medium, and a step of adding a polymerization initiator to the dispersion and performing emulsion polymerization of the monomer mixture, wherein the surfactant is ethylenically unsaturated. A method for producing a long-chain (meth) acrylate emulsion, which is a reactive anionic surfactant having a group.
(11) The length according to (10), wherein the monomer mixture is stirred by a stirring means, and the dispersion is obtained by adding an aqueous medium in which the surfactant is added to the stirred monomer mixture. A method for producing a chain (meth) acrylate emulsion.
(12) The pressure-sensitive adhesive layer obtained by drying the long-chain (meth) acrylate emulsion according to any one of (1) to (9) is laminated on one side or both sides of a film-like substrate. Adhesive tape.

  According to the present invention, there are the effects that the production is easy and excellent adhesive properties can be exhibited.

  Hereinafter, a long-chain (meth) acrylate-based emulsion (hereinafter sometimes referred to as “emulsion”) according to an embodiment of the present invention and a method for producing the same will be described. The emulsion according to the present embodiment is obtained by adding a monomer mixture containing a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, a (meth) acrylate having an alkyl group having 1 to 8 carbon atoms, and a polar monomer to a surfactant. Is an aqueous emulsion containing a copolymer obtained by emulsion polymerization in an aqueous medium to which is added.

  Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms include 16 to 22 carbon atoms such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylates having a linear alkyl group can be used, and these may be used alone or in combination of two or more. (Meth) acrylate means acrylate or methacrylate.

  Examples of the (meth) acrylate having an alkyl group having 1 to 8 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and the like. Alternatively, two or more kinds may be mixed and used.

  Examples of polar monomers include ethylenically unsaturated monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meta ), Ethylenically unsaturated monomers having a hydroxyl group such as acrylate and 2-hydroxyhexyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  The monomer mixture containing each monomer described above is 30 to 70 parts by weight of a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, and 30 to 30 parts of a (meth) acrylate having an alkyl group having 1 to 8 carbon atoms. Although it is preferable to contain 70 weight part and a polar monomer in the ratio of 1-10 weight part, it is not limited to this.

  Here, (meth) acrylate having a linear alkyl group having 16 or more carbon atoms among the monomers contained in the monomer mixture described above is hydrophobic, and (meth) acrylate having an alkyl group having 1 to 8 carbon atoms. Both the polar monomer and the polar monomer are hydrophilic. Such a monomer mixture in which a specific hydrophobic monomer and a hydrophilic monomer are combined tends to be difficult to emulsion-polymerize in an aqueous medium. In the present embodiment, this monomer mixture is emulsion-polymerized in an aqueous medium through the following steps.

  First, the monomer mixture described above is dispersed in an aqueous medium to which a surfactant is added. In this embodiment, a reactive anionic surfactant having an ethylenically unsaturated group (hereinafter sometimes referred to as “reactive surfactant”) is used as the surfactant. Thereby, surfactant can be incorporated in the copolymer obtained by emulsion polymerization, and the amount of free surfactant can be reduced. In addition, when the reactive surfactant described above is used, emulsion polymerization with the surfactant alone becomes possible without using a protective colloid. That is, in the conventional emulsion as described in Patent Document 2 described above, it is necessary to use a protective colloid in combination in order to ensure the stability. However, when the protective colloid is used in combination, there is a problem that the manufacturing process becomes complicated. Further, when the protective colloid is used in combination, there are the following problems in usage forms such as an adhesive tape. That is, when the protective colloid is used in combination, the adhesive strength tends to decrease. Further, the heat resistance of the protective colloid component was low, and there was a tendency to discolor and change when exposed to a high temperature atmosphere. Further, when the adhesive tape is peeled from the adherend, the protective colloid component is transferred to the adherend as an adhesive residue, and the adhesive residue tends to increase. According to this embodiment, as described above, emulsion polymerization with a surfactant alone is possible, so that it is easier to produce than conventional emulsions that use a protective colloid together, and adhesive strength, heat resistance, and resistance are improved. The adhesive residue can be improved, and in combination with the effect of reducing the amount of the free surfactant described above, excellent adhesive properties can be exhibited.

［式中、Ｒ₁およびＲ₂はいずれもアルキル基を示す。ｎおよびｍはいずれも１〜４０の整数を示す。］ Examples of the reactive surfactant described above include compounds represented by the following general formulas (I) and (II).

[Wherein, R ₁ and R ₂ each represents an alkyl group. n and m both represent an integer of 1 to 40. ]

In the formula, examples of the alkyl group represented by R ₁ and R ₂ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, and pentyl group. C1-C20 linear or branched alkyl groups, such as an isopentyl group, a neopentyl group, and a hexyl group.

Since the compounds represented by the general formulas (I) and (II) have no fear of environmental hormones, they can cope with environmental hormone problems. Moreover, a commercial item can be used for the compound represented by general formula (I) and (II). As a commercial item of the compound represented by the general formula (I), R ₁ is a branched alkyl group having 10 to 14 carbon atoms, and “ADEKA rear soap SR-10” manufactured by ADEKA having n = 10 is available. Can be mentioned. As the general formula commercial products of the compound represented by (II), an alkyl group R ₂ is branched 10-14 carbon atoms, m = a is manufactured by ADEKA 10 "ADEKAREASOAP SE-10 N ". In this embodiment, it is preferable to employ the compound represented by the general formula (I) among the compounds represented by the general formulas (I) and (II) exemplified.

  The addition amount of the reactive surfactant is preferably 1 to 40 parts by weight, more preferably 3 to 30 parts by weight, more preferably 10 to 30 parts by weight in terms of solid content with respect to 100 parts by weight of the monomer mixture. More preferably, it is part. If the amount of the reactive surfactant added is too small or large, it may be separated after emulsion polymerization. The reactive surfactant may be added alone, or may be added after a solution previously dissolved or diluted with an aqueous medium or the like.

  Examples of the aqueous medium to which the above-described reactive surfactant is added include water, a mixed medium of water and a water-soluble organic solvent, and the like. In order to eliminate the solvent, water alone is preferable. In the case of using a mixed medium of water and a water-soluble organic solvent, it is preferable that the content of water is larger than the content of the water-soluble organic solvent from the viewpoints of environmental impact and safety. Examples of the water-soluble organic solvent include water-soluble alcohols such as methanol, ethanol, propanol and butanol; acetone and the like. These may be used alone or in combination of two or more.

  The proportion of the aqueous medium is preferably 50 to 400 parts by weight with respect to 100 parts by weight of the monomer mixture, more preferably 100 to 300 parts by weight, and even more preferably 150 to 250 parts by weight. If the proportion of the aqueous medium is too small, the viscosity increases and handling properties decrease, and if it is too large, the productivity decreases, which is not preferable. The total amount of the aqueous medium may be added all at once, or may be added in multiple portions.

  When the above-mentioned monomer mixture is dispersed in such an aqueous medium, a dispersion is obtained. The dispersion is preferably obtained by bringing the monomer mixture into a stirring state with stirring means and adding an aqueous medium to which the reactive surfactant is added to the stirring monomer mixture. Moreover, after adding an aqueous medium, it is preferable to make it a heating state of 50-80 degreeC under stirring, and hold | maintain this state for about 10 minutes-180 minutes.

  Examples of the stirring means include a stirrer, but are not limited thereto as long as the monomer mixture can be brought into a stirring state. Further, the stirring speed is not particularly limited, and can be set as appropriate.

  A high-speed shear mixer may be used as the stirring means. Examples of the high-speed shear mixer include a homogenizer. The high-speed shear mixer may be used alone or in combination with the stirrer described above. Specific examples of the combination include a combination of stirring with a high-speed shear mixer and then stirring with a stirrer. The stirring speed of the high-speed shear mixer is preferably 5,000 to 20,000 rpm. The stirring time of the high speed shear mixer is preferably 30 seconds to 2 minutes.

  The resulting dispersion is usually in an emulsified state. A polymerization initiator is added to this dispersion to carry out emulsion polymerization of the monomer mixture. Examples of the polymerization initiator include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; perchloric acid compounds; perboric acid compounds; benzoyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, tertiary hydro Peroxides such as peroxides and hydrogen peroxide; azo compounds such as 4,4′-azobis (4-cyanopentanoic acid) and azobisisobutyronitrile; potassium persulfate-sodium thiosulfate, hydrogen peroxide -The redox initiator which consists of a combination of peroxides, such as ascorbic acid, and a reducing compound is mentioned, Among the illustrated polymerization initiators, potassium persulfate is preferable.

  The addition amount of the polymerization initiator is preferably 0.05 to 2 parts by weight, more preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the monomer mixture, and 0.1 to 0. More preferably, it is 5 parts by weight. If the addition amount of the polymerization initiator is too small, it is not preferable because the polymerization rate becomes slow and the time required for the completion of the polymerization becomes long. On the other hand, if the polymerization initiator is added too much, the polymerization rate becomes too fast, the reaction heat generated becomes large, and the control of the reaction temperature becomes difficult.

  The polymerization initiator may be added alone, or may be added after a solution previously dissolved or diluted with an aqueous medium or the like. The addition rate of the polymerization initiator is not particularly limited as long as the monomer mixture can be subjected to emulsion polymerization, and can be appropriately set.

  Further, emulsion polymerization may be carried out by further adding a chain transfer agent. Examples of the chain transfer agent include thiol chain transfer agents such as dodecyl mercaptan.

  Emulsion polymerization is preferably performed by heating to 50 to 80 ° C. with stirring and maintaining this state for about 2 to 6 hours. Moreover, it is preferable to perform emulsion polymerization in inert gas atmosphere, such as nitrogen gas and argon gas. In addition, it is preferable to perform the process of obtaining the dispersion liquid mentioned above also in inert gas atmosphere.

  The copolymer obtained by emulsion polymerization is obtained in the form of an aqueous emulsion in which particles are dispersed in an aqueous medium. The average particle size of the emulsion is about 200 to 1000 nm, but is not limited thereto. The solid content concentration of the emulsion is preferably 20 to 60% by weight, and more preferably 35 to 50% by weight. If the solid content concentration is too low, the productivity is lowered, and if it is too high, the viscosity is increased, the handling property is lowered, and the long-term stability tends to be lowered.

  The copolymer contained in the emulsion is a side-chain crystalline polymer that crystallizes at a temperature below the melting point and exhibits phase transition at a temperature above the melting point and exhibits fluidity. Therefore, the emulsion of this embodiment containing this copolymer can be suitably used for adhesive applications and the like.

  As a usage form of the emulsion of this embodiment, it can apply | coat directly to a to-be-adhered body etc., for example, can be used in a film-like form by performing a drying process after spraying. Moreover, if the emulsion of this embodiment is apply | coated on a release film and a drying process is carried out, it can be used with the form of a base material-less film form or a sheet form.

  Furthermore, if the emulsion of this embodiment is applied to one side or both sides of a film-like substrate and dried, it can be used in the form of a tape. That is, the pressure-sensitive adhesive tape of this embodiment using the above-described emulsion is obtained by laminating a pressure-sensitive adhesive layer obtained by drying the above-described emulsion on one or both sides of a film-like substrate.

  Examples of the constituent material of the base material include polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride. Resin.

  The substrate may be either a single layer or a multilayer, and the thickness is usually about 5 to 500 μm. The substrate can be subjected to surface treatment such as corona treatment, plasma treatment, blast treatment, chemical etching treatment, primer treatment, etc. in order to improve the adhesion to the pressure-sensitive adhesive layer.

  As thickness of an adhesive layer, it is preferable that it is 5-60 micrometers, it is more preferable that it is 10-60 micrometers, and it is further more preferable that it is 10-50 micrometers. The thickness of the adhesive layer on one side and the thickness of the adhesive layer on the other side may be the same or different.

  Various additives such as a crosslinking agent, a tackifier, a foaming agent, and an antioxidant can be added to the pressure-sensitive adhesive layer. Of the exemplified additives, it is preferable to add a crosslinking agent. Examples of the crosslinking agent include oxazoline-based crosslinking agents and metal chelate compounds. The addition amount of the cross-linking agent is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight in terms of solid content with respect to 100 parts by weight of the monomer mixture.

  In the present embodiment, the pressure-sensitive adhesive layer on the other side is not particularly limited as long as the pressure-sensitive adhesive layer on one side is obtained by drying the emulsion described above. When the pressure-sensitive adhesive layer on the other side is constituted by what is obtained by drying the emulsion as described above, the composition may be the same as the composition of the pressure-sensitive adhesive layer on one side, May be different.

  Further, the pressure-sensitive adhesive layer on the other surface can be constituted by a pressure-sensitive adhesive layer made of, for example, a pressure-sensitive adhesive. The pressure-sensitive adhesive is a polymer having tackiness, and examples thereof include natural rubber adhesives, synthetic rubber adhesives, styrene / butadiene latex base adhesives, and acrylic adhesives.

  It is preferable to laminate a release film on the surface of the above-mentioned adhesive tape. Examples of the release film include those obtained by applying a release agent such as silicone to the surface of a film made of polyethylene terephthalate or the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to a following example. In the following description, “parts” means parts by weight.

The materials used for the production of the emulsion are as follows.
Surfactant (1): “ADEKA rear soap SR-10” manufactured by ADEKA, represented by the above general formula (I), which is a reactive anionic surfactant having an ethylenically unsaturated group
Surfactant (2): “Nonion HT-515” manufactured by NOF Corporation, which is a non-reactive nonionic surfactant.
Surfactant (3): “Nonion NS-215” manufactured by NOF Corporation, a non-reactive nonionic surfactant
Surfactant (4): “Adeka Hope YES-25” manufactured by ADEKA which is a non-reactive anionic surfactant

Aqueous medium: ion-exchanged water Protective colloid: “PVA224” manufactured by Kuraray, which is partially saponified polyvinyl alcohol having a saponification degree of 88%
Polymerization initiator: Potassium persulfate

<Manufacture of emulsion>
First, 45 parts of behenyl acrylate, 50 parts of methyl acrylate, and 5 parts of acrylic acid were mixed to obtain a monomer mixture. Next, this monomer mixture was added to a separable flask equipped with a stirrer and a gas introduction tube, and nitrogen gas was introduced from the gas introduction tube into a nitrogen gas atmosphere, and the stirring state was set to 120 rpm with the stirrer. . As the stirrer, a stirrer with a shaft provided with a substantially rectangular flat plate-shaped stirring blade at the tip was used. The amount of nitrogen gas introduced was 200 ml / min.

  Next, surfactants and protective colloids were added to the stirred monomer mixture in the combinations shown in Table 1. Specifically, the surfactant and the protective colloid were added after previously dissolving or diluting with an aqueous medium. The protective colloid solution was added by the following two-stage dispersion. First, a surfactant solution was added. Next, the mixture was heated to 70 ° C. with stirring, and this state was maintained for 30 minutes, and then a protective colloid solution was added.

  The aqueous medium was 220 parts in total with respect to 100 parts of the monomer mixture, and 210 parts of this was used for the addition of the surfactant and the protective colloid. Table 1 shows the types of the surfactants and the addition amounts of the surfactant and the protective colloid. The addition amount in Table 1 is a value in terms of solid content with respect to 100 parts of the monomer mixture.

  Next, with the addition of only the surfactant, it was heated to 60 ° C. with stirring, and with the addition of protective colloid, it was heated to 70 ° C. with stirring. A dispersion was obtained by holding for 120 minutes while performing substitution.

  A polymerization initiator is added to the obtained dispersion, and the mixture is heated to 60 ± 1 ° C. with stirring, and this state is maintained for 4 hours to carry out emulsion polymerization to obtain an emulsion having a solid concentration of 33 to 50% by weight. Obtained (Sample Nos. 1 to 11 in Table 1). The addition amount of the polymerization initiator was 0.3 parts with respect to 100 parts of the monomer mixture. The polymerization initiator was previously dissolved in an aqueous medium and dropped into the dispersion over 15 minutes. The remaining 10 parts of the total amount described above was used as the aqueous medium used for dissolving the polymerization initiator. Moreover, solid content concentration was computed from the raw material preparation ratio.

<Evaluation>
About the obtained emulsion, melting | fusing point, storage stability, and adhesive force were evaluated. Each evaluation method is shown below, and the results are also shown in Table 1.

(Melting point)
Whether or not emulsion polymerization was performed was determined from the melting point. That is, the monomer mixture described above was polymerized in advance, and the melting point of the obtained copolymer was measured. Then, the melting point of the copolymer obtained by the solution polymerization is compared with the melting point of the copolymer obtained by the emulsion polymerization described above, and if the difference between the two melting points is within a range of ± 5 ° C. It was determined that emulsion polymerization was performed as a quantitative copolymer.

  Melting point shall mean the temperature at which a particular portion of the polymer that was initially aligned in an ordered arrangement becomes disordered by some equilibrium process. The melting point was measured using a differential thermal scanning calorimeter (DSC) under measurement conditions of 10 ° C./min. The solution polymerization was performed by adding the above monomer mixture to 230 parts of ethyl acetate together with 0.3 part of perbutyl ND (manufactured by NOF Corporation) and stirring at 55 ° C. for 4 hours.

(Left stability)
The emulsion was evaluated by visually observing the state after leaving it at 23 ° C. for 1 month. The evaluation criteria were set as follows.
○: The emulsion state is maintained.
X: Separated.

(Adhesive force)
First, the emulsion was applied to a corona-treated polyethylene terephthalate film and dried at 110 ° C. to obtain a film. Next, under an atmospheric temperature of 80 ° C., the finger was brought into contact with the surface of the film, and the adhesive force was functionally evaluated (finger tack test). The evaluation criteria were set as follows.
○: Adhesive strength is sufficient.
(Triangle | delta): There exists some adhesive force.
X: There is no adhesive force.

  The melting point of the copolymer obtained by solution polymerization of the above monomer mixture was 57 ° C. As is clear from Table 1, sample No. Sample No. 1-11 1 to 5, 8, and 11 are in the emulsion polymerization because the difference from the melting point of the copolymer obtained by solution polymerization is within ± 5 ° C. Therefore, sample no. It can be said that 1 to 5, 8, and 11 are long chain (meth) acrylate emulsions containing a copolymer obtained by emulsion polymerization in an aqueous medium.

  Sample No. Sample Nos. 1 to 5, 8, 11 Nos. 1 to 5 and 8 had good standing stability. Of these, sample no. 1, 2, 4 and 5 showed excellent results in adhesive strength. Sample No. Sample No. 1-9 In Nos. 9 and 10, the aggregates were separated and solidified during the polymerization, and the emulsion polymerization could not be performed.

<Manufacture of emulsion>
First, a monomer mixture was obtained in the same manner as in Example 1 described above, and a surfactant and a protective colloid were added in the combinations shown in Table 2 to the stirred monomer mixture. Next, those added only with the surfactant were heated at 60 ° C. with stirring, and those further added with the protective colloid were heated at 70 ° C. with stirring.

And it replaced with stirring with a stirrer, and stirred by the high-speed shear mixer. The stirring conditions are as follows.
High-speed shear mixer: As One Homogenizer (Main body: AHG-160D, Rotor: HT1025)
Rotation speed: 15,000rpm
Stirring time: 1 minute

  After stirring with a high-speed shear mixer, it was returned to stirring with a stirrer, and this state was maintained for 120 minutes while substituting nitrogen in the system atmosphere to obtain a dispersion. And the dispersion liquid obtained by carrying out similarly to Example 1 mentioned above was emulsion-polymerized, and the emulsion was obtained (sample No. 12-14 in Table 2).

<Evaluation>
The obtained emulsion was evaluated for melting point and standing stability in the same manner as in Example 1 above, and further evaluated for viscosity, coatability, discoloration, and 180 ° peel strength. Each evaluation method is shown below, and the results are also shown in Table 2.

(viscosity)
Measurement was performed using a B-type viscometer at an ambient temperature of 23 ° C.

  The coatability, discoloration and 180 ° peel strength were evaluated by preparing an adhesive tape. Specifically, the emulsion was coated on one side of a substrate made of polyethylene terephthalate having a thickness of 100 μm and subjected to corona discharge treatment, and dried in a drying oven at 110 ° C. for 10 minutes. An adhesive tape having an adhesive layer laminated on one side of a film-like substrate was obtained.

Sample No. For No. 13, the crosslinking agent was added to the emulsion and then applied to the substrate. The used crosslinking agents and addition amounts are as follows.
Crosslinking agent: Oxazoline-based crosslinking agent “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd.
Amount added: 0.5 parts by weight in terms of solid content with respect to 100 parts by weight of polymer solid content

(Coating property)
In the process of obtaining the above-mentioned pressure-sensitive adhesive tape, when the emulsion was applied to the substrate, the presence or absence of repellency of the emulsion on the substrate surface was evaluated by visual observation. The evaluation criteria were set as follows.
○: No repelling occurred.
X: Repelling occurred.

(discoloration)
In the process of obtaining the pressure-sensitive adhesive tape described above, the degree of coloring of the pressure-sensitive adhesive tape after coating was evaluated by visual observation. The evaluation criteria were set as follows.
○: Colorless and transparent △: Colored light yellow ×: Colored dark brown

(180 ° peel strength)
About the obtained adhesive tape, 180 degree peel strength in each atmospheric temperature of 120 degreeC, 80 degreeC, and 23 degreeC was measured based on JISZ0237. Specifically, first, an adhesive tape was attached to a stainless steel (SUS) plate at an ambient temperature of 60 ° C., heated to 80 ° C. and allowed to stand for 20 minutes, and then 300 mm / min using a load cell. The film was peeled at a rate of 180 °, and the 180 ° peel strength at an ambient temperature of 80 ° C. was measured.

  Next, the ambient temperature was raised to 120 ° C. and left to stand for 20 minutes, and then peeled 180 ° at a rate of 300 mm / min using a load cell, and the 180 ° peel strength at an ambient temperature of 120 ° C. was measured.

  Next, the ambient temperature was lowered from 120 ° C. to 23 ° C., and after standing for 20 minutes, the load cell was used to peel 180 ° at a rate of 300 mm / min, and the 180 ° peel strength at 23 ° C. was measured.

<Manufacture of emulsion>
First, when preparing the monomer mixture, a monomer mixture was obtained in the same manner as in Example 1 except that dodecyl mercaptan was added as a chain transfer agent at a ratio of 0.02 parts by weight with respect to 100 parts by weight of the total amount of monomers. . Next, after adding the surfactant in the combination shown in Table 2 in the same manner as in Example 2 except that the obtained monomer mixture was used, the mixture was heated and stirred with a high-speed shear mixer. The mixture was returned to stirring with a stirrer, and this state was maintained for 120 minutes while performing nitrogen substitution in the system atmosphere to obtain a dispersion. And the dispersion liquid obtained by carrying out similarly to Example 1 mentioned above was emulsion-polymerized, and the emulsion was obtained (sample No. 15-17 in Table 2).

  The obtained emulsion was evaluated for melting point and storage stability in the same manner as in Example 1 described above, and further evaluated for viscosity, coatability, discoloration, and 180 ° peel strength in the same manner as in Example 2 above. . The results are also shown in Table 2.

When producing the adhesive tape, the sample No. For 16 and 17, the crosslinking agent was added to the emulsion and then applied to the substrate. The used crosslinking agents and addition amounts are as follows.
Crosslinking agent: Oxazoline-based crosslinking agent “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd.
Sample No. 16 addition amount: 0.5 part by weight in terms of solid content with respect to 100 parts by weight of polymer solid content 17 addition amount: 1.0 part by weight in terms of solid content with respect to 100 parts by weight of polymer solid content

  As apparent from Table 2, the sample No. Nos. 12-17 are emulsion-polymerized because the difference from the melting point of 57 ° C. of the copolymer obtained by solution polymerization is within ± 5 ° C. Therefore, sample no. It can be said that 12 to 17 are long chain (meth) acrylate emulsions containing a copolymer obtained by emulsion polymerization in an aqueous medium. Sample No. It can be seen that Nos. 12 to 17 have a high peel strength at a relatively high temperature of 80 to 120 ° C., a temperature lower than the melting point, and an excellent peelability at 23 ° C. corresponding to room temperature.

Claims (8)

An aqueous medium in which a surfactant is added to a monomer mixture containing a (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, a (meth) acrylate having a C 1-8 alkyl group, and a polar monomer A step of dispersing in to obtain a dispersion,
Adding a polymerization initiator to the dispersion, performing emulsion polymerization of the monomer mixture to obtain a long-chain (meth) acrylate emulsion;
Applying the long-chain (meth) acrylate-based emulsion to one or both sides of a film-like substrate and drying it;
Including
The surfactant is a reactive anionic surfactant having an ethylenically unsaturated group and a compound represented by the following general formula (I):
The method for producing an adhesive tape, wherein the long-chain (meth) acrylate emulsion does not contain a protective colloid.

[Wherein R ₁ represents an alkyl group. n shows the integer of 1-40. ] The pressure-sensitive adhesive tape production according to claim 1, wherein the addition amount of the reactive anionic surfactant having an ethylenically unsaturated group is 1 to 40 parts by weight in terms of solid content with respect to 100 parts by weight of the monomer mixture. Way . The pressure-sensitive adhesive tape according to claim 1 or 2, wherein an addition amount of the reactive anionic surfactant having an ethylenically unsaturated group is 3 to 30 parts by weight in terms of solid content with respect to 100 parts by weight of the monomer mixture. Manufacturing method . The addition amount of the reactive anionic surfactant which has the said ethylenically unsaturated group is 10-30 weight part in conversion of solid content with respect to 100 weight part of monomer mixtures. Manufacturing method of adhesive tape. The manufacturing method of the adhesive tape in any one of Claims 1-4 whose said aqueous medium is water. The manufacturing method of the adhesive tape in any one of Claims 1-5 whose solid content concentration of the said long chain (meth) acrylate type emulsion is 20 to 60 weight%. The manufacturing method of the adhesive tape in any one of Claims 1-6 whose solid content concentration of the said long chain (meth) acrylate type emulsion is 35 to 50 weight%. The method for producing a pressure-sensitive adhesive tape according to claim 1 , wherein the monomer mixture is stirred by a stirring means, and the dispersion is obtained by adding an aqueous medium in which the surfactant is added to the monomer mixture in the stirring state. .