JPH03124786A - Pressure-sensitive adhesive emulsion composition and kraft tape prepared therefrom - Google Patents

Abstract

PURPOSE:To obtain the title compsn. with excellent normal adhesive force and low temp. adhesive force against a resin with a low polarity such as polyolefin resins by incorporating each specified polymer and pitch emulsion and adjusting the content of the latter to be a specified amt. CONSTITUTION:A polymer derived from one or more compd. selected from alkyl (meth)acrylates and vinyl compd. and with a glass transition temp. of -60 to -30 deg.C (e.g. methyl acrylate-2-ethylhexyl acrylate-acrylic acid-N- methylolacrylamide copolymer) and a pitch emulsion with a mean diameter of an emulsion particle of 0.5-3.0mu are incorporated and the content of the pitch emulsion is adjusted to 1-70 pts.wt. (solid content) based on 100 pts.wt. solid component of the emulsion compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a pressure-sensitive adhesive emulsion composition used for adhesive tapes and the like, and a craft tape using the same.

[Conventional technology]

Generally, an acrylic polymer emulsion obtained by emulsion polymerization of an acrylic acid alkyl ester or a methacrylic acid alkyl ester in an aqueous medium is used for adhesive layers of adhesive tapes and the like. Since this type of emulsion does not use organic solvents, it is suitable from the viewpoints of resource saving, environmental health, and safety.Moreover, it has excellent adhesive properties and durability, so it can be It has become widely used as an alternative to other pressure-sensitive adhesives. This type of acrylic polymer emulsion is generally produced by adding an acrylic unsaturated monomer to an aqueous medium together with a modifying monomer such as acrylic acid or vinyl ester as required, in a semi-continuous, two-stage, two-power feed, etc. It is produced by emulsion polymerization using the method described in the following. The acrylic polymer emulsion obtained by this method has a pressure-sensitive adhesive because its main component, the acrylic polymer, has a relatively large molecular weight compared to polymers produced by solution polymerization. High cohesive force can be obtained as an agent.

However, on the other hand, acrylic polymer emulsions have practically insufficient normal adhesion and low-temperature adhesion to containers and films whose surfaces are made of polyolefin resins with low polarity, such as polyethylene and polypropylene. It is strongly requested. Generally, such adhesives are required to have good adhesive properties (adhesion, cohesion, and tack). Therefore, it should be possible to improve the adhesive strength of an acrylic polymer emulsion to a polyolefin resin by increasing the above three physical properties, especially its adhesive strength. but,
It is also necessary to maintain a balance between the three physical properties of adhesion, and it is impossible to improve adhesion while maintaining a balance between them simply by changing the composition of the acrylic polymer itself. It is.

For example, attempts to improve tack generally involve lowering the glass transition temperature of the adhesive polymer, but this results in increased creep and decreased cohesive strength. In order to avoid this, attempts are made to increase the molecular weight or the degree of crosslinking, but doing so will result in a decrease in adhesive strength. In order to improve this adhesive force, a method of increasing wettability (adjustment of viscous fluidity 2 reduction of surface tension) is used, but this results in a decrease in cohesive force. Therefore, by selecting the composition of the acrylic polymer itself, for example, the type of acrylic monomer, it is possible to improve the normal adhesive strength to low polarity polyolefin resins, etc.
It is difficult to improve low-temperature adhesive strength and the like.

Therefore, instead of adjusting the composition of the polymer itself, which is the main component of the acrylic polymer emulsion, other component materials are used in combination with the acrylic polymer. For example, a method of blending a tackifier resin emulsion with an acrylic polymer emulsion has been considered in order to improve the normal adhesive strength to low polarity polyolefin resins. However, in this case, the particles of the acrylic polymer and the particles of the tackifier resin are not uniformly mixed and dispersed in the emulsion, so that the normal adhesive strength is not improved satisfactorily. In addition, when forming the adhesive layer of an adhesive tape or adhesive sheet using such an acrylic polymer-tackifier resin emulsion, roll coating machines, etc. are required because the emulsion has a high structural viscosity. Therefore, when applying the emulsion, there arises a problem that the coating property (roll coating suitability) is poor and the work is difficult. In order to improve this, a method of manufacturing an acrylic polymer emulsion containing a tackifier resin by adding the tackifier resin emulsion at the time of synthesis of the acrylic polymer emulsion instead of simply blending the tackifier resin emulsion (specially Kaisho 58-18
No. 5668) has been proposed. However, in this method, the initial polymerization of the acrylic monomer is carried out in the coexistence of a tackifier resin in a reaction system in which there is no seed polymer that can serve as a nucleus for polymerization. end up being individually dispersed in water, making it impossible to increase the low-temperature adhesive strength to the same level as the normal adhesive strength. In addition, as a method other than this, an emulsion of ethylene-vinyl acetate copolymer (vinyl ester copolymer) is used as a seed, and a pre-emulsion of an acrylic monomer is dropped onto this to perform seed polymerization. Method for improving normal adhesive strength against
No. 16082) has been proposed.

Furthermore, acrylic acid tetrahydroxyfurfuryl monomer and cyclohexyl (meth) acrylic acid monomer are used as modification monomers for acrylic alkyl ester monomers and unsaturated carboxylic acid monomers.
A method of producing an emulsion type adhesive with improved normal adhesive strength to polyolefin resins by copolymerizing acrylate derivatives has also been proposed (Japanese Patent Laid-Open Nos. 57-187476 and 1987-194996). Among these proposed methods, in the case of the method using an ethylene-vinyl acetate copolymer emulsion, it is possible to produce a highly concentrated emulsion due to the presence of a seed polymer that can serve as a nucleus for polymerization of the acrylic monomer. be. However, on the other hand, the structure of the final polymer particles becomes non-uniform, which makes it impossible to sufficiently improve low-temperature adhesion and normal state adhesion. In addition, in the method of using tetrahydroxyfurfuryl acrylate monomer as a modifying monomer, the copolymerizability of these monomers is not good, so the resulting emulsion has poor mechanical stability and chemical stability. The effect of improving adhesive strength to polyolefin resin becomes insufficient.

[Problem to be solved by the invention]

In this way, in the past, even if the composition itself of the acrylic polymer, which is the main component of the acrylic polymer emulsion, was changed, it was not possible to add tack to the acrylic polymer emulsion. Even if methods such as blending agent resins or adding them during polymerization are carried out, the reality is that it has not been possible to improve the normal state adhesive strength and low temperature adhesive strength to low polarity polyolefin resins.

The present invention was developed in view of the above circumstances, and it maintains the balance of the three physical properties of adhesion, and also provides normal adhesive strength to low polarity polyolefin resins and the like.

The purpose of the present invention is to provide a pressure-sensitive adhesive emulsion composition with improved low-temperature adhesive strength and a craft tape using the same.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a pressure-sensitive adhesive emulsion composition containing the following components (A) and (B), wherein the content of component (B) is the solid content of the emulsion composition. The first gist is a pressure-sensitive adhesive emulsion composition characterized in that the solid content is set at 1 to 70 parts by weight per 100 parts by weight, and (A) an acrylic acid alkyl ester, a methacrylic acid alkyl ester, and a vinyl ester. A polymer derived from at least one compound selected from the group consisting of compounds and having a glass transition point within the range of 160°C to -30°C.

(B) A bituminous emulsion in which the average particle diameter of emulsified particles is 0.5 to 3.0 μm.

The second aspect is a kraft tape having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive emulsion composition.

(Function) In the course of repeated research for the purpose of improving the above-mentioned drawbacks of emulsions mainly composed of acrylic polymers, the present inventors focused on the fact that bituminous materials such as asphalt are highly sticky, An attempt was made to introduce this into an emulsion.

That is, the above-mentioned bituminous material was emulsified in water by the action of a surfactant etc. to form a bituminous emulsion, and this was added to the emulsion to prepare an emulsion composition.As a result of investigating the characteristics of the above-mentioned bituminous material, it was found that the above-mentioned bituminous emulsion was The inventors have discovered that when blended into an emulsion within a range of the above range, the normal adhesive strength and low-temperature adhesive strength to polyolefin resins and the like are improved while maintaining the balance of the three adhesive properties, and the present invention has been achieved. The above effects can be obtained by adding a bitumen emulsion because the acrylic ester polymer, etc. in the emulsion composition acts as a matrix in the adhesive layer using the bituminous emulsion. This is thought to be due to the formation of a so-called sea-island structure in which the bituminous particles of the bituminous emulsion are randomly dispersed.

In addition, the present inventors have conceived the idea of applying the above emulsion composition to a pressure-sensitive (adhesive) adhesive layer of a craft tape, and as a result of repeated research, the adhesive layer using the above emulsion composition has the following properties: It has been found that it exhibits adhesive strength equivalent to a rubber-based adhesive layer, and has superior weather resistance and heat resistance compared to rubber-based adhesive layers. Furthermore, the emulsion composition has the advantage that it can be designed as required, and the properties required for the adhesive layer can be adjusted without impairing its physical properties.

The pressure-sensitive adhesive emulsion composition of the present invention contains an acrylic acid alkyl ester as the component (A).

Using a polymer derived from a methacrylic acid alkyl ester and a vinyl compound and having a glass transition point of -60°C to -30°C, the average particle diameter of the emulsified particles is 0.5 to -30°C as the component (B).
Obtained using a 3.0 μm bituminous emulsion.

Acrylic acid alkyl ester and methacrylic acid alkyl ester, which are raw materials for the component (A).

Specific examples of vinyl compounds include the following. That is, acrylic acid alkyl esters include methyl acrylate, ethyl acrylate, 2-
Examples include ethylhexyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and trimethylolpropane triacrylate. Furthermore, there is no problem in using those to which a functional group is bonded. Specific examples of methacrylic acid alkyl esters include methyl methacrylate, ethyl methacrylate,
Normal butyl methacrylate.

isobutyl methacrylate lauryl methacrylate,
Methoxydiethylene methacrylate, methoxypolyethylene glycol methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, glycidyl methacrylate, tetraethylene glycol dimethacrylate,
Examples include trimethylolpropane trimethacrylate. Moreover, there is no problem even if a functional group is bonded to these compounds. Further, specific examples of vinyl compounds include styrene, α-alkylstyrene, α-
Chlorostyrene, vinyl acetate.

Examples include acrylonitrile and vinyl chloride.

These raw material compounds for component (A) may be used alone or in combination. These raw materials for component (A) are polymerized by a conventionally known emulsion polymerization method. In this case, the glass transition point of the polymer is -60°C
It is necessary to set the temperature within the range of ~-30°C. This is because if the glass transition point is outside the above range, sufficient effects cannot be obtained.

The bitumen emulsion of component (B) above is an oil-in-water bitumen emulsion, and specifically, straight asphalt, semi-prone asphalt, blown asphalt, natural asphalt cutback asphalt, coal tar, oil cool, tar pitch, petroleum Examples include emulsions in which bituminous substances such as pitch, tall oil pitch, and fatty acid pitch are emulsified in water either alone or in combination. Emulsification of the above-mentioned bituminous material is generally carried out by appropriately using surfactants, stabilizers, protective colloids, etc. This kind of bituminous emulsion is
Depending on the type of surfactant, it is classified into cationic, anionic, and nonionic. In such a bituminous emulsion, it is necessary that the average particle diameter of the emulsified particles is within the range of 0.5 to 3.0 μm. More preferably 0.5 to 1.0
It is μm.

In addition, in terms of effectiveness, it is recommended to use particles whose particle distribution (weight average particle diameter/number average particle diameter, hereinafter referred to as rdw/dn) is in the range of 1.0 to 1°5. suitable. That is, if the average particle size of the emulsified particles of the bitumen emulsion is outside the above range, it becomes difficult to obtain a proper sea-island structure and the desired effect cannot be obtained. To explain in more detail, when the average particle diameter is less than 0.5 μm, it becomes difficult for the emulsified particles to form a uniformly dispersed system in an emulsion state, and it becomes difficult to form a sea-island structure in a film state.

On the other hand, if the diameter exceeds 3.0 μm, it becomes difficult to form a uniform dispersion system when the bitumen emulsion is blended into the emulsion composition, causing uneven distribution or agglomeration of bitumen emulsion particles, which impairs the mechanical stability of the emulsion composition. This is because chemical stability is extremely deteriorated. In addition, if the above particle size distribution is outside the range of 1.0 to 1.5, it becomes a polydisperse distribution system, and even if the average particle size is within the above appropriate range, the balance between the continuous phase and the dispersed phase will be affected. becomes difficult to maintain, and a continuous phase of bitumen emulsion particles is partially generated in the blend system, and there is a tendency for two phases of polymer emulsion and bitumen emulsion to exist as a continuous phase. As a result, when the continuous phase deforms, cracks occur between the two phases, making it difficult to obtain the effect of improving peel strength.

The pressure-sensitive adhesive emulsion composition of the present invention is produced, for example, as follows. That is, first, the above-mentioned unsaturated monomer such as acrylic acid alkyl ester (raw material compound of component (A)) is mixed with a surfactant, an initiator, a buffer solution, etc. as necessary in a predetermined ratio, The above raw materials are emulsified to form an emulsion by applying a conventionally known semi-continuous emulsion polymerization method, bulk emulsion polymerization method, two-stage emulsion polymerization method, power feed emulsion polymerization method, etc. The bituminous emulsion is then added to this emulsion and mixed. As a result, the desired pressure-sensitive adhesive emulsion composition is obtained.

In this case, the amount of bituminous emulsion blended is 1 to 1 to 100 parts by weight (hereinafter abbreviated as "parts") of the solid content of the emulsion composition.
It is necessary to set the solid content at 70 parts solids. That is,
If the amount of bituminous emulsion used is less than 1 part, the effect of improving adhesive strength will not be observed.

That is, since the number of bituminous emulsion particles is small, the cohesive force decreases, and the desired effect of improving adhesive strength is not observed. On the contrary, 7
If the solid content exceeds 0, the glass transition point of the blend system will significantly exceed 130°C, and therefore the adhesive layer made of the pressure-sensitive adhesive emulsion composition will not reach the rubbery region sufficiently at room temperature. The tack will decrease. Furthermore, in this state, the system becomes an unstable ocean-trench phase mixture, and due to the interfacial tension, the system reverses to the island-trench phase, resulting in a decrease in both adhesion and cohesion. It is from. Therefore, it is necessary to set the proportion of bituminous emulsion used within the above range.

In the pressure-sensitive adhesive emulsion composition of the present invention thus obtained, the polymer of component (A) and the bituminous emulsion of component (B) form a so-called homogeneous dispersion system in an emulsion state, A sea-island structure is formed when the film is dried. That is, in the adhesive layer made of the dry film, a two-phase structure (sea-island structure) is formed in which the bituminous material of the bituminous emulsion is randomly dispersed as particles in the matrix made of the polymer. This makes it possible to significantly improve adhesive force and cohesive force while maintaining a balance among the three physical properties of adhesive force, cohesive force, and tack.

Therefore, in the pressure-sensitive adhesive emulsion composition of the present invention, conventional acrylic polymer emulsions lack normal adhesive strength and low temperature adhesive strength to polyolefin resins, etc.
Low-temperature adhesion strength etc. will be significantly improved.

In addition, the pressure-sensitive adhesive emulsion composition of the present invention is homogeneous and stable and contains almost no bituminous emulsion aggregates, polymer aggregates, or coarse particles composed of them, and therefore has mechanical stability 1 dispersion stability. , good stability over time. Therefore, a good emulsified state is maintained without uneven distribution or release of particles, and a viscosity close to double one tonian is exhibited without exhibiting thixotropic viscosity. Therefore, it has excellent suitability for roll coating, has no coating streaks, has a smooth tacked surface, has a good aesthetic appearance, and is also suitable for printing. In addition, it is also easy to improve the properties of the pressure-sensitive adhesive emulsion composition of the present invention by using additives such as fillers, thickeners, antifoaming agents, etc. as necessary.

Also, the pressure-sensitive adhesive emulsion composition of the present invention is used as an adhesive, and this is coated and dried to a dry weight of 10 to 200 g/rri to form a pressure-sensitive (adhesive) adhesive layer to produce high-quality paper.

It can be applied to adhesive tapes or adhesive sheets in which three layers of surface materials such as coated paper, kraft paper, and polychloride film or release paper are laminated, as well as packaging tapes. The kraft tape thus obtained (adhesive tape described above).

(generally refers to adhesive sheets, packaging tapes, packaging tapes, etc.) has adhesive strength that is approximately the same as that of rubber-based adhesives because the adhesive layer is composed of the above-mentioned pressure-sensitive adhesive emulsion composition. It exhibits excellent adhesive strength, and its adhesive layer is weather resistant.

Excellent heat resistance and water resistance.

〔Effect of the invention〕

As described above, the pressure-sensitive adhesive emulsion composition of the present invention is stable in the emulsion state because the above-mentioned (A) component and (B) component are blended in a specific ratio. When coated and dried to form a contact (adhesive) layer, the adhesive layer exhibits excellent adhesive strength almost equivalent to that of an adhesive layer made of rubber, etc. It has the missing weather resistance, heat resistance, and water resistance.

In particular, by blending the above-mentioned (A) component and (B) component in the above-mentioned specific ratio, the present invention can create an adhesive without losing the balance of the three adhesive physical properties consisting of adhesive force, cohesive force, and tack. The adhesive strength of the layer has been greatly improved, and it has significantly improved normal adhesive strength and low temperature adhesive strength for low polarity resins such as polyolefin resins, which was not possible with conventional acrylic polymer emulsions. Improvements have been achieved. By applying this to the adhesive layer of craft tape, it has adhesive strength almost equivalent to that of rubber-based adhesive layers, and has excellent moisture resistance that is not found in rubber-based adhesive layers. It becomes possible to realize a craft tape with an adhesive layer that is weather resistant, heat resistant, and water resistant.

Next, examples will be described together with comparative examples.

[Example, comparative example]

<Manufacture of emulsion composition> First, the monomer raw materials shown in Table 1 below were blended in the proportions shown in the same table to prepare a monomer mixed solution. On the other hand, 0.3 parts of polyoxyethylene alkylphenyl ether sodium sulfate, 1 part of polyoxyethylene nonylphenyl ether (HLB: 10), and 0.4 parts of sodium acetate were dissolved in 30 parts of ion-exchanged water, A surfactant aqueous solution was prepared. Next, this surfactant aqueous solution was mixed with the monomer mixture having the above composition and emulsified to prepare a monomer pre-emulsion.

Next, 10% by weight of the entire pre-emulsion of the monomer pre-emulsion obtained as described above was added to a reaction vessel equipped with a stirrer, a thermometer, and a cooling cylinder, and 25 parts of ion-exchanged water was added. Added. and,
With nitrogen gas flowing into the reaction vessel, the temperature was raised to 75° C. while stirring, and initial polymerization was performed for 30 minutes. On the other hand, the remaining monomer emulsion 90% by weight and 0.3 parts of sodium topersulfate were dissolved in 7 parts of ion-exchanged water to prepare an aqueous initiator solution. Next, this disclosure-side aqueous solution was dropped into the reaction vessel for 4 hours to carry out a polymerization reaction. The temperature was maintained at 75-80°C throughout the polymerization reaction. After dropping the initiator aqueous solution,
Further, the temperature was maintained at 80''C for 2 hours to carry out post-polymerization.An emulsion was thus prepared.The properties of this emulsion are shown in Table 1 below.

<Production of pressure-sensitive adhesive emulsion composition> To 100 parts of the emulsion produced as described above, the bitumen emulsion shown in Table 1 below was added in the amount shown in the same table, and homodisper (Tokushu Kikai Kogyo Co., Ltd. (manufactured by the company), 3000
A pressure sensitive adhesive emulsion composition was prepared by stirring at rpm for 1°. The properties of the pressure-sensitive adhesive emulsion composition thus obtained are also shown in Table 1 below. However, each characteristic of the emulsion was measured as follows.

■ Solid content concentration (unit: %) According to JIS-6839, the basis weight was determined after drying at 105°C for 3 hours.

■ Average particle size (unit = μm) Dilute the sample emulsion and analyze it using the laser particle size analysis system L.
Measurement was performed using L PA-3000/3100 (manufactured by Otsuka Electronics Co., Ltd.).

(2) Viscosity (unit: cps) Measured according to JIS-6838 using a BM type rotational viscometer at a rotational speed of 60 rpm unless otherwise specified.

■ Mechanical stability (dispersion stability) In order to investigate the mechanical stability when high shear force is applied to the emulsion for a certain period of time, a high shear force of 110,000 rp for about 1 o minutes was applied to the sample using a high speed rotational viscometer manufactured by HAAKE. The state of generation of aggregates and changes in viscosity after addition to the emulsion were observed, and the mechanical stability was evaluated based on the situation.

The evaluation was on a four-level scale: good, slightly good, slightly poor, and poor.

■ Phase form of component (A) and component (B) In order to observe the phase form of the bituminous emulsion of component (A) and component (B) in the emulsion, the sample emulsion was formed into a film, and K, Kat,
The method developed by O et al. (Magazine Electron Mic)
r.

sc.
008) at a magnification of 50,000 times. According to this method, there is a difference in electron beam transmittance between the domains of component (A) and the bitumen emulsion component (B) when the sample emulsicon is formed into a film, and the domains of component (A) have a pale gray color. On the other hand, the domains of the bituminous emulsion of component (B) are photographed as dark brown, so the phase states of both can be seen.

Therefore, the results of this observation were displayed as follows.

(Expression...Situation observed) A... A state in which bituminous emulsion grain domains of component (B) as a dispersed phase are randomly dispersed in component (A) as a continuous phase (sea-island structure) ).

B...The bituminous emulsion particles of component (B) aggregate and form a continuous phase (
A) A state where it is unevenly distributed in the ingredients.

C: A state in which component (A) and some bitumen emulsion particles exist as a continuous phase, and the remaining bitumen emulsion grain domains are unevenly distributed in component (A).

D: A state in which the two phases are completely separated and unevenly distributed.

E: A state in which bituminous emulsion particles of component (B) are randomly dispersed in the form of particles without forming domains in component (A) as a continuous phase.

(The following is a blank space) In addition, the properties such as adhesive strength of the pressure-sensitive adhesive emulsion composition obtained as described above were determined, and the results are shown in Table 2 below.

The above characteristics were measured as follows.

■Normal adhesive strength (normal temperature adhesive strength) (Unit: g/25mn
+) On one side of a polyester film with a thickness of 50 am,
Each adhesive sample was applied so that the thickness after drying would be 25 μm, and dried at 105° C. for 5 minutes to prepare an adhesive tape. Then, the adhesive-applied side of this adhesive tape was
20237, stainless steel plate (hereinafter referred to as “SS
After bonding to the surface of a "plate"), the 180° peeling adhesive strength was measured at 20° C. and in an atmosphere of 65% RH.

In addition, a high-density polyethylene board (hereinafter abbreviated as "rPE board") was used as an adherend instead of the SS board, and the adhesive strength thereof was expressed as normal adhesive strength in the same manner as above.

■ Low-temperature adhesion strength (unit: g/25ea) The temperature condition for measuring the normal-state adhesive strength is -20"C, but the procedure is the same as the normal-state adhesive strength measurement, and the adhesive strength is calculated as the low-temperature adhesive strength. It was displayed as .

■ Water-resistant adhesive strength (unit: 25 plates) A sample with the adhesive coated side of the adhesive tape used for normal adhesive strength measurement bonded to the surface of a PE board in accordance with JIS-ZO237 was immersed in water for 3 days, and then Take enough of
The 180° peel adhesive strength was measured in an atmosphere of 20° C. and 165% RH.

■ Ball tack <Tack> (J, Dow method) (Unit: ball number) Measured at an inclination angle of 30'' according to JIS-20237.

■ Holding force (unit: 2 minutes) According to JIS-20237, load is 1 kg, 40℃
The elapsed time until the load dropped in an atmosphere of 965% RH was measured and displayed. Note that this holding force is a measure of cohesive force.

(Margin) From the results in Tables 1 and 2, it can be seen that the pressure-sensitive adhesive emulsion compositions of Examples of the present invention have good properties such as mechanical stability and coatability, and have good adhesive strength, cohesive force, and tack. It can be seen that the balance of physical properties is improved, and the normal adhesive strength to polyolefins etc. is significantly improved. On the other hand, in Comparative Example 1, the adhesive strength under normal conditions, especially the adhesive strength to the PE plate, was extremely low, and a shipping phenomenon occurred when measuring the low temperature adhesive strength. Moreover, the physical property balance of adhesive force, cohesive force, and tack is not at a satisfactory level. In Comparative Example 2, the adhesive force, cohesive force, and tack physical property balance were significantly reduced, and the phase state of the bitumen emulsion phase and polymer phase was such that the bitumen emulsion particles aggregated and were unevenly distributed in the continuous phase. It was in a bad condition.

Comparative Example 3 is inferior in properties such as mechanical stability to Comparative Example 2, and the physical property balance is also lower than that of Comparative Example 2.
It was the same. Further, the phase conditions of the bituminous emulsion phase and the polymerization phase were poor as in Comparative Example 2.

Comparative Example 4 had good mechanical stability, but poor adhesive strength under normal conditions, and poor phase condition between the bituminous emulsion and the polymer. In Comparative Example 5, agglomeration of bituminous emulsion particles occurred, and when the mechanical stability was examined, it was found that the emulsion broke 1 minute after applying a high shearing force, indicating poor stability.

(Manufacture of Kraft Tape) After neutralizing the pressure-sensitive adhesive emulsion composition of Example 1 and that of Comparative Example 1 obtained as described above with 25% ammonia water, Vissurf (manufactured by Kao Corporation), A thickener) was added to adjust the viscosity to 8000 cps. This was coated at a rate of 60 g/pot using a 3-roll reverse roll coater at a coating speed of 80/min on unbleached kraft paper for tape with a weight of 73 g/bo processed by Tart Pack, and then packed. produced craft tape for

Moreover, as Comparative Example 7, a packing tape using natural rubber as an adhesive layer was shown. This tape was manufactured as follows. That is, first, 100 parts of masticated natural rubber (manufactured by Shell Chemical Company), 50 parts of zinc white, 75 parts of natural rosin (manufactured by Crosby Company), S
2 parts of ym-di-β-naphthyl-P-diaminophenylene and 10 parts of lanolin were placed in a reaction vessel equipped with a stirring and temperature raising device, and kneaded at a temperature equal to or higher than the softening point of natural rubber and natural resin rosin.

Next, this was naturally cooled and diluted with n-hexane to adjust the solid content concentration to 50%. This was produced by using this in place of the pressure-sensitive adhesive emulsion composition. Moreover, as Comparative Example 8, a packing tape using synthetic rubber for the adhesive layer was shown.

This tape was manufactured as follows. That is, first, ethylene vinyl acetate copolymer (EV
A, manufactured by Sumima Kagaku Kogyo Co., Ltd.) 40 parts, 10 parts of polyvinyl acetate, 40 parts of aromatic hydrocarbon formalin resin, 10 parts of microcrystalline wax, and 1 part of antioxidant were melted in a stirrer and heated at 200°C for 2 hours. The mixture was melt blended. This was molded and cooled in a block-shaped hot melt molding machine, and then an appropriate amount was taken, placed on a heated roll, and coated on the kraft paper at a rate of 60 g/rrt.

The low-speed tensile strength of the packing tape obtained as described above was measured and shown in Table 3 below.

The above characteristics were measured as follows.

(Low speed tensile adhesive strength) (Unit: g/25+nm) Each sample was bonded to the surface of a cardboard according to JIS-ZO237. Then, the tensile speed condition was set to 0.5a/1
Adhesive strength was measured in the same manner as in the measurement of normal adhesive strength, except that lIin was used.

The adhesive strength thus obtained was expressed as low-speed tensile adhesive strength.

(Margin below) As is clear from the results in Table 3, Conducted height measurement Low speed tensile strength is Superior to comparable products I understand that.

Claims (2)

[Claims] (1) A pressure-sensitive adhesive emulsion composition containing the following components (A) and (B), wherein the content of component (B) is 1 to 70 parts by weight based on 100 parts by weight of solid content of the emulsion composition.
A pressure-sensitive adhesive emulsion composition characterized in that the solid content is set in parts by weight. (A) A polymer derived from at least one compound selected from the group consisting of an acrylic acid alkyl ester, a methacrylic acid alkyl ester, and a vinyl compound, and having a glass transition point within the range of -60°C to -30°C. (B) A bituminous emulsion in which the average particle diameter of emulsified particles is 0.5 to 3.0 μm. (2) A craft tape in which the pressure-sensitive adhesive layer is composed of the pressure-sensitive adhesive emulsion composition according to claim (1).