JPH111674A - Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive composition which gives a uniform dispersion in water and does not have an adverse effect on repulping when pressure-sensitive adhesive paper labels, pressuresensitive adhesive tapes for a spine, etc., made therefrom are disintegrated with waste paper to produce regenerated paper, and which, when used for a label for a bottle, ensures firm bonding during use and makes it possible to readily peel and remove the label by water washing for cleaning, and provide a pressure-sensitive adhesive sheet made therefrom. SOLUTION: The pressure-sensitive adhesive composition 2 contains a water- dispersible polyester (A) having a branched structure and synthesized from a dicarboxylic acid, a glycol, a branched monomer having a functionality of three or higher, and a monomer having -SO3 Na groups, and a rosin-, terpene-or styrene-base tackifier resin (B). The pressure-sensitive adhesive sheet is obtained by applying the composition 2 to at least one side of a base material or release base material 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet. More specifically, the present invention relates to a pressure-sensitive adhesive composition which is uniformly dispersed in water and does not adversely affect repulping when paper adhesive labels, spine adhesive tapes and the like are disintegrated together with waste paper into recycled paper. And an adhesive sheet.

[0002]

2. Description of the Related Art A sheet coated with an adhesive does not require any help such as a solvent or heat and is adhered to another surface with a very low pressure such as a finger pressure, and is easily peeled off without leaving any trace on the adhered surface. It is used in a wide range of applications from a release type that can be used to a permanent adhesive type that is used for applications that do not require peeling due to strong adhesion. Among these, adhesive paper with paper as a support and an adhesive applied uniformly on one side is bound into printed matter such as magazines as seals, labels, stickers, etc. with printed on the other side. Often.
From the viewpoint of contributing to resources and environmental issues, such as protection of forest resources, saving of pulp wood resources, reduction of solid waste, and energy saving in the pulp manufacturing process, collection and reuse of used paper is being promoted. The recovered waste paper is disintegrated into original pulp fibers by a pulper. However, if the adhesive paper is mixed in the waste paper, the adhesive applied to the adhesive paper is insoluble in water, so it will not dissolve in water even if it is miniaturized in the pulper, It is sent to the subsequent papermaking process as it is. Recovered waste paper is sorted for contraindicated items at the waste paper collection stage and at the paper mill, but it is difficult to completely sort it because it is a work that relies on human labor. If an adhesive that does not dissolve in water is sent to the papermaking process, the adhesive will not only adhere to wires and blankets, causing trouble in the process, but also leave the adhesive in the recycled paper and deteriorate the paper formation. Let it. For this reason, there is a need for a pressure-sensitive adhesive composition that is easily dissolved or uniformly dispersed in water in a pulper and is stable in a used paper recycling process. The adhesive is applied to a plastic film or printing paper, printed, and used as a label for a glass bottle or the like. Such labels preferably adhere strongly to the bottle during the distribution and use of the bottle, and preferably release easily when the bottle is collected and washed. However, it is not easy for a label coated with an acrylic pressure-sensitive adhesive which is widely used at present to achieve both the adhesive strength during distribution and use and the removability during washing. For this reason, it is easy to attach the label to the bottle, firmly adheres to the bottle during the distribution stage and during use, and during cleaning,
There is a need for an adhesive composition that can be easily peeled off without leaving a trace by washing with water.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for disintegrating paper adhesive labels, spine adhesive tapes and the like together with waste paper into recycled paper without dispersing them uniformly in water without adversely affecting repulping. The object of the present invention is to provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet which can be strongly adhered during use when used as a label for bottles, and can be easily peeled off and removed by washing with water during washing.

[0004]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that water-dispersible polyesters having a sulfonate group and a branched structure can be used.
Adhesive paper coated with a pressure-sensitive adhesive composition containing a specific tackifier resin has good disintegration in water, and the label coated with the composition adheres strongly to the bottle. ,
Further, they have found that they can be easily peeled off by washing with water, and have completed the present invention based on this finding. That is,
The present invention relates to (1) (A) dicarboxylic acid, glycol, 3
A water-dispersible polyester having a branched structure which is synthesized from a monomer having a functional or more branched monomers and -SO ₃ Na group, (B) a rosin-based tackifier resins, terpene tackifier resin or a styrene based tackifying Pressure-sensitive adhesive composition comprising an adhesive resin, and (2) a pressure-sensitive adhesive sheet obtained by applying the pressure-sensitive adhesive composition according to (1) to at least one surface of a substrate or a release substrate , Is provided. Further, as a preferred embodiment of the present invention, (3) water-dispersible polyester was measured at 25 ° C. on a solution of 0.25 g of polymer / 100 ml of solvent using a mixed solvent of phenol / tetrachloroethane (weight ratio: 60/40). Logarithmic viscosity number is 0.1 dl / g or more, glass transition temperature is 20 ° C or less, and softening point by ring and ball method is 70 ° C.
The pressure-sensitive adhesive composition according to the above item (1) can be mentioned.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The present invention compositions are used dicarboxylic acids, glycols, water-dispersible polyester having a branched structure which is synthesized from a monomer having a tri- or higher functional branching monomers and -SO ₃ Na group . There is no particular limitation on the dicarboxylic acid used, for example, phthalic acid,
Examples thereof include aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, and aliphatic dicarboxylic acids such as glutaric acid, adipic acid and pimelic acid. The glycol used is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, and polyethylene glycol. There is no particular limitation on the trifunctional or higher functional branching monomer used, and examples thereof include trimethylolpropane, glycerin, and pentaerythritol. Use -S
The monomer having an O ₃ Na group is not particularly limited, and examples thereof include dimethyl-4-sodiosulfophthalate, dimethyl-5-sodiosulfoisophthalate, and dimethyl-2-sodiosulfoterephthalate. The method for synthesizing the water-dispersible polyester having a branched structure used in the present invention is not particularly limited,
For example, as described in International Publication No. WO95 / 18191, titanium isopropoxide or the like is added as a catalyst to a mixture of raw material monomers, and the mixture is gradually heated in an inert gas atmosphere. By doing so, it is possible to obtain a water-dispersible polyester having a target —SO ₃ Na group and having a branched structure.

The water-dispersible polyester used in the present invention is phenol / tetrachloroethane (weight ratio 60
/ 40) Using a mixed solvent, it is preferable that the logarithmic viscosity number measured at 25 ° C. of a solution of 0.25 g of polymer / 100 ml of solvent is 0.1 dl / g or more, and 0.2 to 0.5 d.
More preferably, it is 1 / g. Logarithmic viscosity number is 0.1dl
If it is less than / g, the cohesive force of the pressure-sensitive adhesive composition may be insufficient. If the logarithmic viscosity number exceeds 0.5 dl / g, the coating workability of the pressure-sensitive adhesive composition may decrease. The water-dispersible polyester having a branched structure used in the present invention preferably has a glass transition temperature of 20C or lower, more preferably -20 to 10C, and -1.
The temperature is more preferably 0 to 0 ° C. When the glass transition temperature exceeds 20 ° C., the tackiness of the pressure-sensitive adhesive composition may be insufficient. When the glass transition temperature is lower than −20 ° C., the holding power of the pressure-sensitive adhesive composition may be insufficient.

In the present invention, a rosin-based tackifier resin, a terpene-based tackifier resin or a styrene-based tackifier resin is used. The tackifier resin used in the present invention preferably has a softening point of 60 ° C. or higher. Examples of the rosin-based tackifier resin include modified rosins such as maleated rosin, fumarated rosin, polyesterified rosin, high hydroxyl rosin, and high acid rosin. Examples of the terpene-based tackifier resin include a copolymer resin of α-pinene and phenol, and a polymer mainly composed of β-pinene.
Examples of the styrene-based tackifier resin include a styrene-maleic anhydride resin. The rosin-based tackifier resin, terpene-based tackifier resin and styrene-based tackifier resin are all compatible with the water-dispersible polyester having the above-mentioned branched structure, and have tack, tackiness, cohesion, etc. Pressure-sensitive adhesive composition having an excellent balance of pressure-sensitive adhesive properties. Further, the pressure-sensitive adhesive composition containing these tackifier resins hardly deteriorates in physical properties due to aging with heat and humidity. The water-dispersible polyester having the above-mentioned branched structure, a rosin-based tackifier resin, a terpene-based tackifier resin or a styrene-based tackifier resin is mixed with a pressure-sensitive adhesive composition, which is applied to paper to form a pressure-sensitive adhesive paper. In this case, the disintegration in water is good, but excellent disintegration is obtained particularly when a tackifier resin modified with an organic acid anhydride such as a styrene-maleic anhydride resin is used. In the present invention, the rosin-based tackifier resin, the terpene-based tackifier resin, or the styrene-based tackifier resin may be used alone or in combination of two or more.

The pressure-sensitive adhesive sheet of the present invention comprises (A) a dicarboxylic acid, a glycol, a trifunctional or higher functional branching monomer and
PSA composition containing water-dispersible polyester having a branched structure synthesized from a monomer having an SO ₃ Na group, and (B) a rosin-based tackifier resin, a terpene-based tackifier resin, or a styrene-based tackifier resin An object is applied to at least one surface of a substrate or a release substrate. The substrate on which the pressure-sensitive adhesive composition is applied is not particularly limited. For example, high-quality paper, coated paper, kraft paper, paper such as thin paper, polyethylene terephthalate film, polybutylene terephthalate film, polyethylene film, polypropylene film, etc. Synthetic resin film. In some cases, the pressure-sensitive adhesive composition is applied to a release substrate, and when used, the release substrate is peeled off and used as a sheet-shaped pressure-sensitive adhesive composition. There is no particular limitation on the release base material used in such a case, for example, high-quality polylaminate release paper, kraft polylaminate release paper, glassine release paper, clay-coated release paper, or polyethylene terephthalate film, polybutylene terephthalate film, polyethylene Examples thereof include those obtained by applying a release agent to a synthetic resin film such as a film or a polypropylene film. The method of applying the pressure-sensitive adhesive composition to the substrate or the release substrate is not particularly limited, and can be applied by, for example, a Hommelt method, or as a solution in which the pressure-sensitive adhesive composition is dissolved in an organic solvent. Can be painted. When applying by a hot melt method, a water-dispersible polyester having a branched structure and a tackifier resin are mixed in a predetermined ratio,
Extruded into a film from an extruder equipped with a T-die, and the hot-melt film-like pressure-sensitive adhesive immediately after being extruded,
Press on paper, release paper or release film and cool. When applied as a solution, the organic solvent used is not particularly limited, and examples thereof include toluene, ethyl acetate, and methyl ethyl ketone. When the pressure-sensitive adhesive composition is applied as a solution, the concentration of the solution is 10 to 60% by weight.
And more preferably 30 to 40% by weight. If the concentration of the solution is less than 10% by weight,
There is a possibility that the amount of the solvent used is too large, which is economically disadvantageous. When the concentration of the solution exceeds 60% by weight, the viscosity of the solution becomes too high, and the coating workability may be reduced. In the pressure-sensitive adhesive sheet of the present invention, the coating amount of the pressure-sensitive adhesive composition is not particularly limited and can be appropriately selected depending on the use of the pressure-sensitive adhesive sheet.
It is preferably g / m ^2, and more preferably 10 to 30 g / m ^2. Coating amount is 5g / m as solid content
^If it is less than ² , sufficient adhesiveness may not be exhibited. A coating amount exceeding 50 g / m ² as a solid content is unnecessary for a pressure-sensitive adhesive sheet for ordinary use.

The mode of the pressure-sensitive adhesive sheet of the present invention is not particularly limited and can be arbitrarily selected according to the form of use. FIG. 1 is a partial cross-sectional view illustrating an embodiment of the adhesive sheet of the present invention. FIG. 1A shows an adhesive paper having a basis weight of 9
0 g / m adhesive composition 2 on ² of gloss paper 1 is assigned 20 g / m ² coating as a solid content, and further the release paper 3 stacked. FIG. 1B shows an adhesive film having a thickness of 50%.
The pressure-sensitive adhesive composition 2 is applied on a polyethylene terephthalate (PET) film 4 having a thickness of 20 μm in a solid content of 20 g / m ² , and a release paper 3 is further laminated thereon. FIG. 1 (c)
This is a non-carrier type pressure-sensitive adhesive sheet, in which a pressure-sensitive adhesive composition 2 is applied on a release paper 3 at a solid content of 20 g / m ² , and the release paper 3 is further laminated. When using a non-carrier-type pressure-sensitive adhesive sheet, one side of the release paper is peeled off and adhered to the target surface, and then the other side of the release paper is peeled off and used as a double-sided pressure-sensitive adhesive sheet. FIG.
(d) is an adhesive tape having a basis weight of 55 g / g on which a polyethylene film 5 having a thickness of 15 μm is laminated.
2 adhesive composition 2 as a solid component onto fine paper 6 m ²
0 g / m ² is applied and wound up. A release agent such as a silicone resin may be applied to the surface of the substrate shown in FIG. When the pressure-sensitive adhesive sheet of the present invention is pressure-sensitive adhesive paper, the pressure-sensitive adhesive composition is dispersed as water in a pulper when it is recovered as waste paper and subjected to a regeneration step because of its good disintegration properties. For this reason, the wire and the blanket are not contaminated, and a high-quality recycled paper with good formation can be obtained. When the pressure-sensitive adhesive sheet of the present invention is a label, the label attached to a bottle or the like does not peel off during transportation or use, and when collecting and cleaning the bottle, the label may leave a trace by washing with water. The cleaning process can be simplified because the film is easily peeled off from the bottle. When the bottle is a polyethylene terephthalate (PET) bottle, if a polyethylene terephthalate film coated with the pressure-sensitive adhesive composition of the present invention is used as a label, almost all components are polyester, so that they are compatible with each other. Therefore, the label can be sent to the bottle collecting step without removing the label.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In Examples and Comparative Examples, the evaluation of the pressure-sensitive adhesive sheet was performed by the following method. (1) Adhesive strength It is evaluated according to JIS Z 023778. The adhesive sheet is cut into a width of 25 mm and a length of about 250 mm, and is pressure-bonded to a stainless steel plate polished with No. 280 water-resistant abrasive paper using a manual pressure roller. Using a load cell type tensile tester, peeling was performed at 180 ° at a peeling speed of 300 mm / min, and the resistance value when peeled was measured. The measurement is performed 20 minutes after the crimping. (2) Ball tack Evaluate according to JIS Z 023712. Cut the adhesive sheet to a width of 15 mm and a length of about 300 mm.
Set on a 0 degree slope and paste a polyester film for the runway. JIS from 100mm length runway
Roll a steel ball of 1/16 to 1 inch specified in B1501 and find the largest steel ball that stops in the measuring section with a length of 100 mm, and let the ball number be 32 times the nominal number of the ball. (3) Holding force It is evaluated according to JIS Z 023711. The adhesive sheet is cut into a width of 25 mm and a length of 150 mm, and is pressure-bonded to a stainless steel plate polished with No. 280 water-resistant abrasive paper using a manual pressure roller so that the area of 25 × 25 mm is in contact.
In a constant temperature room at 40 ° C., a sample pressed on a stainless steel plate is suspended vertically, a static load of 1 kg is applied, and the time until the sample falls or after 20 hours is measured. (4) Formation Handsheets are prepared and evaluated according to JIS P 8209. Put about 24 g of adhesive paper together with about 2,000 ml of water in a container of a disintegrator, disintegrate sufficiently,
Dilute to a concentration of. A predetermined amount of the diluted raw material is poured into a container of a sheet machine, and wet paper is formed on a wire mesh. Wet paper,
Coaching, pressing and drying to get handsheets. The obtained handsheets were illuminated from the back, and the fibers were uniformly dispersed and no foreign matter was observed. (5) Disintegration Five sheets of the above handsheets are superimposed, and 20 g / cm
^After applying a load of ² and leaving it in a constant temperature bath at 70 ° C. for 3 days, it is further left in an atmosphere of 23 ° C. and 65% RH for another day. Thereafter, the five handsheets are peeled off by hand in order from the top, and the state of blocking is observed. When the disintegration is good and the pressure-sensitive adhesive does not remain on the handsheet or the residual amount is small, no blocking occurs. ○ if no blocking, × if blocking
And Example 1 -SO ₃ water dispersible polyester branched structure having a Na group [Eastman Chemical Company, AQ1045] 100 parts by weight polyhydric rosin Arakawa Chemical Industries (Ltd.), KE
381] is mixed with 10 parts by weight, and the cylinder temperature is 175
Extruder set at 180 ° C. and a T-die temperature of 180 ° C., extruded onto gloss paper having a basis weight of 90 g / m ^{2 so} as to have a coating amount of 20 g / m ² , pressure-bonded, and bonded with a release paper to adhere. Paper was made. The adhesive strength of this adhesive paper is 13N / 25mm
Met. The ball tack was 6, and no displacement was observed after 20 hours in the holding force test.
No foreign matter was observed in the formation observation, and no blocking occurred in the disintegration test. Example 2 —100 parts by weight of a water-dispersible polyester having a branched structure having an SO ₃ Na group [Eastman Chemical Co., AQ1045] and 20 parts by weight of a terpene resin [Yasuhara Chemical Co., Ltd., YS Resin PX800] are dissolved in 180 g of toluene. and, the gross paper basis weight 90 g / m ^2, coated with a comma coater such that the amount with the coating is 20 g / m ² as a solid content, dried, to prepare a pressure-sensitive adhesive sheet by bonding release paper.
The adhesive strength of this adhesive paper was 12 N / 25 mm. The ball tack was 6, which was 20 in the holding force test.
No displacement was observed after hours. No foreign matter was observed in the formation observation, and no blocking occurred in the disintegration test. Example 3 -SO ₃ water dispersible polyester branched structure having a Na group [Eastman Chemical Company, AQ1350] 100 parts by weight of styrene maleic acid resin [Corp. Gifu Shellac Manufacturing Plant, GSM-1002] 15 parts by weight Was mixed and extruded onto a gloss paper having a basis weight of 90 g / m ² using an extruder set at a cylinder temperature of 175 ° C. and a T-die temperature of 180 ° C. so as to have a coating amount of 20 g / m ^2, and pressed. An adhesive paper was produced by laminating release paper. The adhesive strength of this adhesive paper was 14 N / 25 mm. The ball tack was 4, and no displacement was observed after 20 hours in the holding force test. No foreign matter was observed in the formation observation, and no blocking occurred in the disintegration test. Comparative Example 1 An acrylic emulsion pressure-sensitive adhesive [Lintech Co., Ltd., PW] was applied on a gloss paper having a basis weight of 90 g / m ^{2 so that} the applied amount became 20 g / m ² as a solid content, dried, and a release paper was obtained. Adhesive paper was produced by bonding. The adhesive strength of this adhesive paper is
18 N / 25 mm. The ball tack was 10, and no displacement was observed after 20 hours in the holding force test. However, foreign matter was observed in formation observation, and blocking occurred in the disintegration test. Comparative Example 2-A branched water-dispersible polyester having an SO ₃ Na group [Eastman Chemical Co., AQ1045] was obtained by using an extruder set at a cylinder temperature of 175 ° C and a T-die temperature of 180 ° C, with a basis weight of 90 g / m ² of gloss paper, and pressed extruded to weight with the coating is 20 g / m ^2, to prepare a pressure-sensitive adhesive sheet by bonding release paper. The adhesive strength of this adhesive paper was 2 N / 25 mm. The ball tack was less than 2, and no displacement was observed after 20 hours in the holding force test. No foreign matter was observed in the formation observation, and no blocking occurred in the disintegration test. Table 1 shows the results of Examples 1 to 3 and Comparative Examples 1 and 2.

[0011]

[Table 1]

From the results in Table 1, it can be seen that the pressure-sensitive adhesive papers of Examples 1 to 3 coated with the pressure-sensitive adhesive composition of the present invention have moderate adhesive strength and ball tack values as pressure-sensitive adhesive papers. The hand paper obtained by recycling the adhesive paper has good texture and good disintegration. On the other hand, the conventional pressure-sensitive adhesive paper of Comparative Example 1 coated with the acrylic emulsion pressure-sensitive adhesive had a strong adhesive force, but the handsheets obtained by recycling the pressure-sensitive adhesive paper had a poor formation and a disintegration property. Inferior in terms of. Moreover, without the addition of tackifier resins, adhesive paper of Comparative Example 2 was subjected coated only water-dispersible polyester of branched structure having a -SO ₃ Na group, formation and macerating property is good, Adhesive strength is weak and hardly practical for adhesive paper. Example 4 -SO ₃ water dispersible polyester branched structure having a Na group [Eastman Chemical Company, AQ1045] 100 parts by weight polyhydric rosin Arakawa Chemical Industries (Ltd.), KE
381] is mixed with 10 parts by weight, and the cylinder temperature is 175
Extruder set at 180 ° C. and a T-die temperature of 180 ° C., extruded onto a high-quality paper having a basis weight of 55 g / m ^{2 so} as to have a coating amount of 20 g / m ² and pressure-bonded. Paper was made. This adhesive paper was punched out into a circle having a diameter of 5 cm to produce a label, and the release paper was peeled off and affixed to a glass bottle. 23 ° C, 65%
When left in the RH environment for one month, no label peeling or floating phenomenon was observed. When the glass bottle to which the label was attached was immersed in water at 40 ° C., the label was completely removed in 30 minutes.

[0013]

The paper adhesive label and spine adhesive tape obtained by applying the pressure-sensitive adhesive composition of the present invention, when disintegrated together with waste paper into recycled paper, are uniformly dispersed in water and repulped. When a label for a bottle is used without adversely affecting the chemical conversion, it adheres firmly during use and can be easily peeled off and removed by washing with water during washing.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating an embodiment of the adhesive sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gloss paper 2 Adhesive composition 3 Release paper 4 Polyethylene terephthalate (PET) film 5 Polyethylene film 6 Fine paper

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C08G63 / 688 C08G63 / 688 (C09J 167/02 193: 04) (C09J 167/02 191: 00) (C09J 167 / 02 125: 04)

Claims (2)

[Claims] 1. A water-dispersible polyester having a branched structure synthesized from (A) a dicarboxylic acid, a glycol, a trifunctional or higher-functional branched monomer and a monomer having an -SO ₃ Na group, and (B) a rosin-based tackifier. An adhesive composition comprising an adhesive resin, a terpene-based tackifier resin, or a styrene-based tackifier resin. 2. A pressure-sensitive adhesive sheet obtained by applying the pressure-sensitive adhesive composition according to claim 1 to at least one surface of a substrate or a release substrate.