JPH0475270B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention does not exhibit tackiness at room temperature (20°C), but it develops tackiness when heated, and once tackiness is developed, it maintains that tackiness for a long time even if the temperature is returned to room temperature. The present invention relates to an aqueous resin dispersion composition that provides a heat-sensitive adhesive film. Conventional adhesive labels, stickers, stickers, etc.
A pressure-sensitive adhesive is coated on the back side of printed art paper, aluminum foil, or polyethylene terephthalate film, and the surface of this adhesive layer is covered with release paper. This release paper is peeled off and discarded prior to use, which is undesirable from the viewpoint of material cost and resource saving. On the other hand, labels, stickers, or sheets using hot-melt adhesives are non-tacky at room temperature, but when activated by heat and the heat source is removed, the adhesiveness lasts for a short time, for example, several seconds, which poses problems in workability. As an adhesive to solve the above-mentioned drawbacks, there is an example of a heat-sensitive adhesive prepared by blending a heat-sensitive material with a tackifying agent, as described in Japanese Patent Application Laid-Open No. 51-81832, but it is heat-activated. The disadvantage is that it takes too long, for example, several minutes. Also, JP-A-51-111246
There is a heat-activated adhesive composition prepared by blending a block copolymer of styrene and butadiene or styrene and isobrene with a tackifying agent and a crystalline plasticizer, as described in the above publication. It has the disadvantage of poor workability, such as re-adhesion of cut surfaces when punching to create labels, stickers, or sheets. As a method to improve such defects, (A) 100 parts by weight of ethylene/vinyl acetate copolymer (B) 40 to 150 parts by weight of adhesive resin (C) 30 to 250 parts by weight of crystalline plasticizer (D) Wax 0 to 100 parts by weight 70 parts by weight A composition containing the above components (A) to (D) in the above proportions is melt-coated onto a sheet-like substrate and cooled, or a solution obtained by dissolving the composition in an organic solvent is coated and dried. A heat-sensitive adhesive sheet was proposed that was non-adhesive at room temperature, activated by heating, and remained adhesive for a while even after the heating source was removed (Japanese Patent Application Laid-Open No. 1986-1999).
106984). This heat-sensitive adhesive sheet does not exhibit adhesiveness at room temperature, so no release paper is required, and it also has the advantage that the cut surface does not stick to the punching blade when punching for uses such as labels and stickers. However, in order for the heat-sensitive adhesive sheet to stop exhibiting tackiness at room temperature, it is necessary to wait 1 to 2 weeks after applying the melt of the composition to the sheet substrate, and it is necessary to apply the melt of the composition to the sheet substrate. When applied to a base material, it is necessary to wait one week after application.
Storage before shipping is troublesome. Furthermore, the latter method using a solvent is unfavorable in terms of environmental safety and hygiene. In general, tacky resin (a) with a softening point of 50 to 135°C does not exhibit tackiness at room temperature (20°C), but when formed into a uniform composition with crystalline plasticizer (b), it becomes tacky even at room temperature. shows. In the above-mentioned pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet stops showing tackiness at room temperature 1 to 2 weeks after the adhesive resin composition is applied to the base material, but this is because the composition becomes uniform as the crystallization of the crystalline plasticizer progresses. This is due to the separation of adhesive resin and crystalline plasticizer. The present inventors investigated various resin compositions for the purpose of improving the drawback that conventional coated products require 1 to 2 weeks to become non-tacky at room temperature, and found that an aqueous dispersion of a tacky resin and a plastic If an aqueous dispersion composition prepared by mixing an aqueous dispersion of a thermoplastic resin containing a thermoplastic resin is used as a coating agent, the coating film obtained by scattering water by drying will not exhibit tackiness at room temperature, but it will become tacky when heated. The inventors have discovered that the adhesive exhibits tackiness, and that once it exhibits tackiness, it maintains its tackiness for a long time even after cooling to room temperature, and has thus arrived at the present invention. That is, the present invention includes: Part [I]: An aqueous dispersion of a sticky resin selected from rosin and its derivatives, and terpenes and its derivatives and having a softening point of 50 to 130°C Part []: (A) Ethylene resin and a thermoplastic resin selected from styrenic block copolymers or hydrogenated products thereof 30 to 80% by weight (B) Plasticizer selected from process oils or phthalate ester liquid plasticizers and crystalline plasticizers
70 to 20% by weight Aqueous dispersion of a homogeneous mixture of the above components in the above proportions.The solid content ratio of liquid [I] and liquid [] is 1/9 to 9/1.
The minimum film forming temperature is 50 to 135.
The present invention provides an aqueous resin dispersion composition for a hot melt adhesive at a temperature of .degree. In the practice of the present invention, the aqueous dispersion of adhesive resin as liquid [I] is prepared by dispersing 100 parts by weight of adhesive resin in 80 to 1000 parts by weight of water using 2 to 30 parts by weight of a dispersant. . Adhesive resins with a softening point of 50 to 130°C include abietic acid rosin, its water additives, their maleic acid adducts, metal salts, glycerin, pentaerythritol, esterified products with alcohols such as ethylene glycol, diethylene glycol, etc. Terpenes and their derivatives such as rosin derivatives, homopolymers of α-pinene, β-pinene, dipentene, etc. or copolymers thereof, terpene phenol copolymers, and water additives thereof are used. If the softening point is less than 50°C, the resulting coating film is likely to block. Examples of the dispersant include surfactants, carboxymethyl cellulose, partially saponified polyvinyl alcohol, and partially neutralized salts of polyacrylic acid. The aqueous dispersion of the adhesive resin can be produced, for example, by the following method. That is, the adhesive resin is heated in a container equipped with a stirring device and a heating device until it melts, thereby obtaining a molten adhesive resin. The temperature at this time is usually in the range of 90 to 190°C. While stirring the hot-melt adhesive resin thus obtained, an aqueous solution of a dispersant is added to obtain an emulsion in which water is the dispersed phase and the adhesive resin is the continuous phase. The amount of water used at this stage is 70 to 85
This is the amount in weight%. Then add warm water with vigorous stirring. The amount of hot water added is appropriately determined so that the concentration of the adhesive resin is 5 to 70% by weight, preferably 10 to 55% by weight. At this stage, the emulsion is inverted, with water becoming the continuous phase and the sticky resin becoming the dispersed phase. When this is cooled, an aqueous dispersion of finely dispersed solid adhesive resin is obtained (JP-A-57-
Publication No. 98558). It is also possible to carry out the above steps continuously using a twin screw extruder disclosed in JP-A-56-2149 as shown in the production example below. Next, the aqueous dispersion of a resin containing a plasticizer in the liquid [] is (A) a thermoplastic resin.
30-80% by weight, preferably 40-70% by weight (B) Plasticizer
100 parts by weight of a homogeneous mixture of 70 to 20% by weight, preferably 60 to 30% by weight, is dispersed in 80 to 1000 parts by weight of water using 2 to 30 parts by weight of a dispersant. This liquid [] is produced by using a homogeneous molten mixture of the components (A) and (B) in place of the adhesive resin in the method for producing the liquid [I]. Examples of the thermoplastic resin of component (A) include ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, ethylene-propylene random copolymer, and ethylene-butene random copolymer. copolymer, ethylene-propylene-butene copolymer, ethylene-
Acrylic acid copolymer, ethylene-methacrylic acid copolymer and these metals (Na, K, Li, Zn)
Ethylene resin such as salt; styrene-butadiene-
Styrenic block copolymers such as styrene copolymers and styrene-isoprene-styrene copolymers, or hydrogenated products thereof are used. The plasticizer as component (B) is a liquid plasticizer or a crystalline plasticizer that plasticizes the adhesive resin. Here, the crystalline plasticizer is in a solid crystalline state at a temperature below the softening point, and once melted, it does not crystallize immediately but slowly crystallizes even after the heat is removed. As the liquid plasticizer, a process oil or a phthalate ester plasticizer such as diethyl phthalate, di-n-butyl phthalate, dihexyl phthalate, and dioctyl phthalate is used. Examples of the latter crystalline plasticizer include dicyclohexyl phthalate, diphenyl phthalate, di-α-naphthyl phthalate glycol stearate, triphenyl phosphate, diphenacyl azelaate, and the like. The reason why a thermoplastic resin is used in combination with a plasticizer in the liquid [] is that a storage-stable aqueous dispersion cannot be obtained with the plasticizer alone without the aid of a solvent. Furthermore, the presence of the thermoplastic resin improves the anti-blocking properties of the coating film obtained from the aqueous dispersion composition. The plasticizer is preferably 20 to 70% by weight based on the sum of the plasticizer and thermoplastic resin in the liquid [].
30-60% by weight is used. In the case of liquid [I] and liquid [], stirring is performed. Note that gelation often occurs when the liquids [I] and [liquid] have different ionic properties, so it is natural that the adhesive, dispersant, and thermoplastic resin must be selected. A minimum of a resin aqueous dispersion in which liquid [I] and liquid [] are uniformly mixed at a ratio of 1/9 to 9/1, preferably 2/8 to 7/3 (liquid [I]/liquid []). The film forming temperature (MFT) is at least 50°C or higher, preferably 55 to 130°C. If the MFT is less than 50°C, a film obtained by coating the composition on a substrate such as paper or aluminum foil may block in the summer or become sticky before heating. Such an aqueous dispersion composition is applied to a substrate such as paper, aluminum foil, or resin film, and dried at a temperature lower than the MFT, or heated at a temperature higher than the MFT for a time that does not form a continuous film to form a discontinuous film. is formed. The sheet-like material, such as paper, synthetic paper, aluminum foil, etc., on which the discontinuous film is formed is cut out and used as stickers, labels, etc. This discontinuous film does not exhibit tackiness at room temperature, but when heated to a temperature above the MFT, the plasticizer migrates to the tacky resin and becomes a uniform composition, forming a transparent continuous film. This continuous film exhibits tackiness. Even when the film is then cooled to room temperature, the film remains
Stays sticky for 20 days. The aqueous resin dispersion composition of the present invention can be used not only as an adhesive for heat-sensitive adhesive labels as described above, but also as a backing material for carpets; wallpaper, and an adhesive for leather. Next, the present invention will be explained in further detail by giving Examples and Comparative Examples. Note that % and parts in the examples are based on weight unless otherwise specified. Production example of dispersant N,N-dimethylaminoethyl methacrylate
62.9 parts (0.4 mol), butyl methacrylate 71 parts (0.5 mol), lauryl methacrylate 25.4 parts (0.1 mol) and 200 parts of isopropyl alcohol in a 4-necked flask equipped with a stirrer, reflux condenser, thermometer, and dropping funnel. After purging with nitrogen gas, 0.9 part of 2,2'-azobisisobutyronitrile was added as a polymerization initiator, and a polymerization reaction was carried out at 80°C for 4 hours. Next, after neutralizing with 24 parts (0.4 mol) of acetic acid, water was added while distilling off the isopropyl alcohol, to finally obtain a viscous aqueous dispersant solution with a solid content of 35%. Example 1 Glycerin ester of rosin (Ester Gum AAV manufactured by Arakawa Chemical Co., Ltd., softening point 83°C) was extruded at a rate of 100 parts by weight/hour using a twin screw extruder (PCM45 manufactured by Ikegai Tekko Co., Ltd.).
hopper and kneaded at 110℃, while
The aqueous dispersant solution obtained in the above example was continuously fed at a rate of 20 parts by weight/hour from the first feed port provided in the metering zone of the extruder using a gear pump.
Subsequently, hot water was continuously supplied by a plunger pump at a rate of 70 parts by weight/hour from the second supply port provided on the die side of the extruder, and the extrusion temperature was
Extrusion was performed at 110° C. and 250 rpm to continuously produce a white aqueous dispersion, which was designated as liquid [I]. The MFT of this dispersion was 65°C, and the average particle size of its solid content was about 0.5 microns. In the same way, ethylene/vinyl acetate copolymer [Ebuafrex 220 (trade name) manufactured by Mitsui Petrochemical Industries, Ltd.; vinyl acetate content 28%, melting point 74°C, MFR=
150g/10 minutes] 50% and dicyclohexyl phthalate [crystalline plasticizer manufactured by Wako Pure Chemical Industries, Ltd.] 50% mixture.
It was continuously fed from the hopper of a co-rotating intermeshing twin-screw extruder (Ikegai Tekko Co., Ltd. trade name PCM45, triple thread shallow groove type, L/D=30) at a rate of 100 parts/hour. Further, 22.9 parts of the dispersant aqueous solution (solid content: 8 parts) was further added to hot water through the supply port provided in the vent part of the same extruder.
While continuously supplying an aqueous solution diluted with 147.1 parts at a rate of 170 parts/hour under pressure using a gear pump (discharge pressure 3 Kg/cm ² G), the heating temperature (cylinder temperature, the same hereinafter) was 130°C and the screw rotation speed. 100rpm
The mixture was continuously extruded to obtain a milky white polymer aqueous dispersion (first liquid, solid content concentration 40%). The average particle size of this stuff is about 0.5 microns and the MFT is 62
It was warm at ℃. This liquid [] and the liquid [I] described above were mixed at room temperature in a solid content ratio as shown in Table 1, and the results were as shown in the table.
An aqueous dispersion composition of MFT was obtained. This aqueous dispersion composition was applied to art paper having a basis weight of 160 g/m ² so that the coating amount was 20 g/m ² when dry, and dried at 20° C. for one day to obtain a discontinuous film. This film did not exhibit any stickiness. Art paper with this film is 500mm long and 300mm wide.
It was then cut into a sheet with scissors and used as a sample piece. This sample piece was heated to 100℃ for 10 seconds and then heated to 23℃, 65%
Leave to cool for one day and night in a constant temperature and humidity room at RH, and then use a low density polyethylene film (thickness 50μ) and a heat sealer at a pressure of 2Kg/cm ² , 23℃, and 65%RH.
Pressure-sensitive adhesive was applied for seconds. This pressure-sensitive adhesive sample was cut to a width of 15 mm, and the tensile speed was measured using an autograph (IS-2000 model manufactured by Shimadzu Corporation) according to the method described in JIS K-6854.
The peeling test was conducted at 300 mm/min. Table 1 also shows the results of pressure-sensitive bonding of the coated and dried test pieces under the same conditions without heating.

[Table] Comparative Example 1 To a mixture of 50 parts of the rosin glycerin ester used in Example 1-d, 25 parts of ethylene-vinyl acetate copolymer, and 25 parts of dicyclohexyl phthalate, 900 parts of toluene was added, and then heated to 50°C for 2 hours. A uniform resin solution was obtained by heating for a certain period of time. The coating amount (solid content) of this solution on art paper is 20
g/m ² at 20° C., dried for 6 hours, and then stored in a vacuum chamber at 10 mmHg for 2 days and nights to obtain art paper with a continuous coating film. This continuous film was tacky and required an additional 5 days to become tacky. Also, after heating to 100℃ for 10 seconds, 23℃, 65%
The adhesive strength was 570 when left to cool for a day and night at RH and pressure-sensitive adhesive bonded for 1 second using low density polyethylene film at a pressure of 2Kg/cm ² at 23℃ and 65%RH.
g/15mm width. Furthermore, the adhesive strength when heating to 100° C. was omitted was 550 g/15 mm width. Example 2 70 parts of ethylene-vinyl acetate copolymer (vinyl acetate content 20%, MFR 400 g/10 minutes) and paraffinic process oil "PW-90" (trade name manufactured by Idemitsu Kosan)
A co-rotating intermeshing twin-screw extruder (trade name of Ikegai Tekko Co., Ltd.) was used to process 30 parts of the mixture at a rate of 100 parts/hour.
It was continuously supplied from a hopper of PCM45, triple thread shallow groove type, L/D = 30). In addition, from the supply port provided in the first pent part of the same extruder, 22.9 parts/hour of the aqueous solution of the neutralized acrylic copolymer obtained in the above production example was added (8 parts as solid content of the dispersant). /hour) using a gear pump (discharge pressure 3Kg/cm ² G) and continuously supply hot water through the supply port provided in the second pent part.
The mixture was continuously extruded at a heating temperature (cylinder temperature, hereinafter the same) of 110° C. while continuously supplying the mixture with a trochoid pump at a ratio of parts/hour to obtain a milky white aqueous dispersion. The MFT of this aqueous dispersion was 58°C. This aqueous dispersion is referred to as the liquid (2). Fifty parts of this liquid (2) and 50 parts of liquid (I) of Example 1 were mixed at 20°C to prepare an aqueous resin dispersion composition (MFT 60°C). This composition was evaluated in the same manner as in Example 1-d. The resulting art paper with a discontinuous coating had no tack at 20°C. The adhesive strength after heating at 100℃ for 10 seconds and storing at room temperature for 1 day was 830g. The width was 15 mm, and the adhesive strength without heating was 0 g/15 mm width. Comparative Example 2 A mixture of 35 parts of the ethylene/vinyl acetate copolymer used in Example 2, 15 parts of process oil, and 50 parts of rosin glycerin ester was mixed at a rate of 100 parts/hour in a co-rotating intermeshing twin-screw extruder. (Ikegai Tekko Co., Ltd. product name: PCM45, triple thread shallow groove type,
It was continuously supplied from a hopper with L/D=30). In addition, from the supply port provided in the first pent part of the same extruder, 22.9 parts/hour of the aqueous solution of the neutralized acrylic copolymer obtained in the above production example was added (8 parts as solid content of the dispersant). /hour) using a gear pump (discharge pressure 3Kg/cm ² G) and continuously supply hot water through the supply port provided in the second vent part.
It was continuously extruded at a heating temperature (cylinder temperature, hereinafter the same) of 110°C while continuously supplying the mixture at a ratio of parts/hour by a trochoid pump to obtain a milky white aqueous dispersion (MFT 18°C). This aqueous dispersion was applied onto art paper in the same manner as in Example 1, and dried at 20°C for one day to obtain a continuous coating film. This coating film was sticky. When this and polyethylene film were adhered in the same manner as in Example 1, the adhesive strength was 100°C and 10°C.
The width of the sample that had been heated for 2 seconds was 520 g/15 mm, and the width of the sample that had not been coated was 470 g/15 mm. Comparative Example 3 In Example 2, diethylene glycol ester of hydrogenated rosin “Ester Gum HD” (trade name, manufactured by Arakawa Chemical Co., Ltd.) was used instead of glycerin ester of rosin.
Aqueous dispersion (MFT30℃) using a softening point of 5℃)
I got it. This was designated as liquid (I), and 50 parts of this and 50 parts of liquid () of Example 2 were uniformly mixed at 20°C.
A resin aqueous dispersion composition (MFT 15°C) was obtained. This composition was applied onto art paper in the same manner as in Example 1 to obtain a coating film. This coating film was sticky. When this and a polyethylene film were bonded together in the same manner as in Example 1, the adhesive strength was 930 g/15 mm width for the one that had been heated at 100°C for 10 seconds, and 910 g/15 mm width for the one that had not been heated. Ta. Example 3 Arakawa Chemical's hydrogenated rosin "Hibale" (trade name): A co-rotating intermeshing twin-screw extruder (Ikegai Tekko Co., Ltd. trade name PCM45, three-thread screw shallow It was continuously supplied from a groove-type hopper (L/D=30). In addition, 17 parts of a 30% aqueous solution of partially saponified polyvinyl alcohol "PVA420" manufactured by Kuraray Co., Ltd. was added as a dispersant through the supply port provided in the first pent part of the same extruder.
Gear pump (discharge pressure 3Kg/cm ²
G) while continuously supplying water under pressure at a rate of 90 parts/hour from the supply port provided in the second pent part using a trochoid pump.
Continuous extrusion was performed at a heating temperature (cylinder temperature, hereinafter the same) of 100°C to obtain a milky white aqueous dispersion with an average particle size of 0.2μ. This aqueous dispersion (MFT58°C) was designated as liquid (I). Next, instead of 100 parts of hydrogenated rosin, styrene-
A milky white aqueous dispersion having an average particle size of 2.5 μm was obtained in the same manner as above except that 100 parts of a mixture of 40 parts of isoprene-styrene block copolymer and 60 parts of dicyclohexyl phthalate was used. This is called the liquid (2). 80 parts of the above liquid (I) and 20 parts of liquid () at 20°C.
and mixed to obtain an aqueous dispersion composition with an MFT of 72°C. Using this composition, it was applied onto art paper in the same manner as in Example 1, and dried at 20°C for one day and night to form a discontinuous coating film. This coating had no tack. Example 1 This coating film and polyethylene film were
It was adhered in the same manner as above, and the adhesive strength was measured. The adhesive strength of the material subjected to a heating history of 100° C. for 10 seconds was 730 g/15 mm width, and that of the material subjected to no heat history was 0 g/15 mm width. Comparative Example 3 A mixture of rosin glycerin ester used in the liquid [I] and dicyclohexyl phthalate used in the liquid [] in Example 1 (wt% ratio 67/
Example 1 except that 33) was supplied at 100 parts by weight/hour.
An aqueous dispersion (I') was obtained in the same manner as above. The MFT of this dispersion was 10°C or less, and the average particle size of the solid content was 0.3 microns. Similarly, an aqueous dispersion ('') was obtained in the same manner as in Example 1, except that the ethylene/vinyl acetate copolymer used in the liquid [] of Example I was supplied at a rate of 100 parts by weight/hour. The MFT of this product was 72℃, and the average particle size was 0.7μ.This liquid (') and the liquid (I') were mixed at room temperature in a solids ratio of 50/50. An aqueous dispersion composition was obtained.The MFT of this product was 18°C, and this composition was coated on art paper in the same manner as in Example 1 and dried at 20°C for one day. The film was continuous and sticky at room temperature, making it unsuitable for use as a hot melt adhesive. Example 4 Ethylene-butene copolymer (Mitsui Petrochemical Co., Ltd. "Tafmer A20090" MFR = 18 g/ 10 minutes) 70% and triphenyl phosphate (crystalline plasticizer manufactured by Wako Pure Chemical Industries, Ltd.)
The twin-screw extruder used in Example-1 was prepared by using a 30% mixture at a rate of 100 parts by weight/hour and a 30% aqueous solution of Kuraray's partially saponified polyvinyl alcohol "PVA420" at a rate of 17 parts by weight/hour as a dispersant. A milky white aqueous dispersion with an average particle size of 1.3μ was obtained by supplying water at 90°C from the second supply at a rate of 90 parts by weight/hour. (MFT45℃) was obtained, and using an aqueous terpene phenol dispersion ("Staron 2130" made by Yasukawa Oil Co., Ltd., softening point 125℃) as the liquid (I),
The solid content ratio with the liquid (liquid (I)/liquid ()) is
They were mixed at 20°C so that the ratio was 80/20 to obtain an aqueous dispersion composition with an MFT of 105°C. Using this composition, it was applied onto art paper in the same manner as in Example 1 and dried at 20°C for one day and night to form a discontinuous coating film. This coating showed no tack. Examples of this film and polyethylene film
It was adhered in the same manner as in 1 and the adhesive strength was measured.
The one heated at 130°C for 10 seconds had a width of 610 g/15 mm, and the one without heating had a width of 0 g/15 mm.

Claims (1)

[Claims] 1 Liquid [I]: Aqueous dispersion of a sticky resin with a softening point of 50 to 130°C selected from rosin and derivatives thereof, and terpenes and derivatives thereof Liquid []: (A) Ethylene-based Thermoplastic resin selected from resins, styrenic block copolymers, or hydrogenated products thereof 30 to 80% by weight (B) Plasticizer selected from process oil or phthalate ester liquid plasticizers and crystalline plasticizers
70 to 20% by weight Aqueous dispersion of a homogeneous mixture of the above components in the above proportions.The solid content ratio of liquid [I] and liquid [] is 1/9 to 9/1.
The minimum film forming temperature is 50 to 135.
Resin aqueous dispersion composition for hot melt adhesives at ℃.