JP7356261B2 - Adhesive sheet for labels - Google Patents

Description

The present invention relates to an adhesive sheet for labels.

Conventionally, an organic solvent type adhesive composition has been used as an adhesive composition for forming an adhesive layer of an adhesive sheet. However, there was a problem that the organic solvent volatilized during coating. Another problem was that a small amount of organic solvent remained in the adhesive layer of the adhesive sheet.
On the other hand, emulsion-type adhesive compositions are superior to organic solvent-type adhesive compositions in terms of environment, safety, hygiene, and the like.
Therefore, in recent years, emulsion-type adhesive compositions have been increasingly used as adhesive compositions for forming adhesive layers of adhesive sheets.

Furthermore, in recent years, environmental issues such as global warming have been emphasized, and regulations for suppressing emissions of greenhouse gases such as carbon dioxide have been strengthened. From this point of view, for example, Patent Document 1 discloses a pressure-sensitive adhesive sheet that can reduce the amount of fossil resource-based materials used and reduce greenhouse gas emissions during incineration, etc. by incorporating plant-derived components. has also been proposed. To explain in detail, plant-derived ingredients (hereinafter also referred to as "biomass materials") emit carbon dioxide, which is a greenhouse gas, when burned, etc.; Because it is absorbed from the atmosphere through photosynthesis during the growth process of plants, it does not substantially increase the amount of carbon dioxide in the atmosphere. In other words, biomass materials can be regarded as carbon-neutral materials that do not substantially increase or decrease carbon by circulating in the global environment in a relatively short period of time. Since biomass materials are carbon-neutral, adhesive sheets that contain biomass materials and reduce the amount of fossil resource-based materials used can be used to reduce the amount of carbon dioxide derived from fossil-based materials during incineration, etc. Emissions, in other words, carbon dioxide emissions originating from materials that are difficult to recycle in a relatively short period of time, are reduced, and greenhouse gas emissions during incineration, etc., are reduced.

International Publication No. 2015/056499

By the way, it is difficult for a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from an emulsion-type pressure-sensitive adhesive composition to ensure sufficient adhesion to polyolefin. Polyolefins are often used in containers and packaging for foods and the like. Therefore, from the viewpoint of increasing the versatility of pressure-sensitive adhesive sheets having pressure-sensitive adhesive layers formed from emulsion-type pressure-sensitive adhesive compositions, a tackifier is blended into emulsion-type pressure-sensitive adhesive compositions to provide sufficient adhesiveness to polyolefins. It is conceivable to ensure that

In addition, from the perspective of suppressing greenhouse gas emissions during incineration, etc., we use emulsion-type adhesive compositions as tackifiers that do not substantially increase carbon dioxide in the atmosphere during incineration, etc. It is also possible to increase the biomass content of the adhesive layer by using a plant-derived resin, which is a carbon-neutral material.

Here, in addition to ensuring adhesion to polyolefin and increasing the degree of biomass of the adhesive layer, there are other characteristics that should be imparted to the adhesive sheet.

Specifically, many adherends to which adhesive sheets are attached have curved surfaces. Therefore, there is also a need for pressure-sensitive adhesive sheets that have excellent adhesion properties, particularly to curved surfaces.

Further, when an adhesive sheet is used as a label, the label is often attached using a labeling machine or the like. At that time, by improving the tack of the label, it becomes possible to instantly apply the label to the adherend using a labeling machine. Thereby, the speed of the process of attaching a label to an adherend can be increased, and productivity can be improved. Moreover, as mentioned above, polyolefins are often used in a wide variety of applications, such as containers and packaging for foods and the like. Therefore, it is required to ensure sufficient label tack even for polyolefins.

However, a pressure-sensitive adhesive sheet that satisfies all of these requirements has not yet been studied.

Therefore, the present invention can exhibit sufficient adhesive strength even to polyolefin, has excellent adhesion to curved surfaces, and has sufficient tack to polyolefin, and also has a high degree of biomass in the adhesive layer. Another purpose is to provide adhesive sheets for labels.

In order to solve this problem, the inventors of the present invention conducted extensive studies and found that the degree of biomass of an adhesive layer formed from an emulsion-type adhesive composition containing an emulsion-type adhesive and an emulsion-type tackifier was set within a specific range. It has been discovered that a pressure-sensitive adhesive sheet adjusted to the following can solve the above problems.
That is, the present invention relates to the following [1] to [5].
[1] Comprising at least a base material and an adhesive layer provided on one side of the base material, the adhesive layer is made of an emulsion-type adhesive composition containing an emulsion-type adhesive and an emulsion-type tackifier. The tackifier resin of the emulsion-type tackifier that is formed includes one or more selected from rosin resin and terpene resin, and the biomass degree of the adhesive layer is 2.9% or more and less than 24.8%. , adhesive sheet for labels.
[2] The pressure-sensitive adhesive sheet for labels according to [1] above, wherein the pressure-sensitive adhesive layer has a biomass degree of 2.9% or more and 20.0% or less.
[3] The pressure-sensitive adhesive sheet for labels according to [1] or [2] above, wherein the emulsion-type pressure-sensitive adhesive includes an acrylic emulsion-type pressure-sensitive adhesive.
[4] The pressure-sensitive adhesive sheet for labels according to any one of [1] to [3] above, wherein the tackifier resin includes one or more selected from rosin resins having a softening point of 80° C. or higher and 170° C. or lower.
[5] The adhesive sheet for labels according to any one of [1] to [4] above, which is used as a punched label.

According to the present invention, it is possible to exhibit sufficient adhesion to polyolefin, and it has excellent adhesion to curved surfaces and has sufficient tack to polyolefin, and the biomass content of the adhesive layer is also increased. In addition, it becomes possible to provide adhesive sheets for labels.

FIG. 1 is a cross-sectional view of a pressure-sensitive adhesive sheet for labels according to one embodiment of the present invention. FIG. 3 is a cross-sectional view of a pressure-sensitive adhesive sheet for labels according to another embodiment of the present invention. (A) is a plan view of the continuous label body, and (B) is a sectional view of the continuous label body.

[Aspects of adhesive sheet for labels]
The adhesive sheet of the present invention includes at least a base material and an adhesive layer provided on one side of the base material, and the adhesive layer is an emulsion-type adhesive containing an emulsion-type adhesive and an emulsion-type tackifier. The tackifier resin of the emulsion-type tackifier is one or more selected from rosin resin and terpene resin, and the biomass degree of the adhesive layer is 2.9% or more and 24.8%. less than %.
If the degree of biomass of the adhesive layer is less than 2.9%, sufficient adhesion to polyolefin cannot be ensured, and the adhesion to curved surfaces is also poor.
Moreover, if the degree of biomass of the adhesive layer is 24.8% or more, the adhesion to curved surfaces is poor.
When the biomass degree of the adhesive layer is 2.9% or more and less than 24.8%, it can exhibit sufficient adhesion to polyolefin, has excellent adhesion to curved surfaces, and has sufficient tack to polyolefin. It is possible to obtain a pressure-sensitive adhesive sheet for labels in which biomass is secured and the degree of biomass in the pressure-sensitive adhesive layer is also increased.
Here, from the viewpoint of making it easier to exhibit the effects of the present invention, in the pressure-sensitive adhesive sheet for labels according to one embodiment of the present invention, the biomass degree of the pressure-sensitive adhesive layer is preferably 2.9% or more and 20.0% or less, or more. Preferably it is 2.9% or more and 18.7% or less.
Further, from the viewpoint of making it easier to improve the tack on polyolefin, in the adhesive sheet for labels according to one embodiment of the present invention, the biomass degree of the adhesive layer is preferably 2.9% or more and 15.0% or less, more preferably It is 2.9% or more and 11.5% or less.
In addition, in this specification, "the degree of biomass of an adhesive layer" is a value calculated from the following formula (A).
(Biomass degree of adhesive layer) = (X/Y) x 100 ... (A)
In formula (A), "X" is the solid mass of the plant-derived component in the emulsion-type adhesive composition. In the present invention, the plant-derived component includes a plant-derived emulsion type tackifier, and its solid content corresponds to "X". "Y" is the total mass of the solid content of the emulsion-type tackifier and the solid content of the emulsion-type adhesive in the emulsion-type adhesive composition.

[Configuration of adhesive sheet for labels]
Cross-sectional views of a pressure-sensitive adhesive sheet for labels according to one embodiment of the present invention are shown in FIGS. 1 and 2.
The adhesive sheet for labels 1a shown in FIG. 1 has a laminated structure in which an adhesive layer 3 is directly laminated on one side of a base material 2.
Here, the adhesive sheet for labels according to one embodiment of the present invention has a laminated structure in which the base material 2, the adhesive layer 3, and the release liner 4 are laminated in this order, as shown in the adhesive sheet for labels 1b shown in FIG. may have. In this case, when using the adhesive sheet for labels, the release liner 4 is peeled off from the adhesive sheet for labels, and the exposed adhesive layer 3 is applied to the adherend.
However, the structure of the pressure-sensitive adhesive sheet for labels according to one embodiment of the present invention is not limited to these. For example, another layer may be provided between the base material 2 and the adhesive layer 3. Examples of the other layer include a primer layer and the like.
Further, as the other layer, a metallic luster layer may be provided from the viewpoint of providing a pressure-sensitive adhesive sheet for labels with excellent design. Examples of the metallic luster layer include a metallic vapor deposited film, a metallic foil, and a metallic lustrous printed layer formed by a known printing method using a printing ink containing metallic lustrous particles such as metal particles.

Next, FIG. 3 shows a continuous label body 10 as an adhesive sheet for labels according to one embodiment of the present invention. 3(A) is a plan view of the continuous label body 10, and FIG. 3(B) is a sectional view of the continuous label body 10.
The continuous label body 10 includes a label 11 made of a base material 12 punched into a shape such as a rectangular plane and an adhesive layer 13 provided on the back surface of the base material 11, which is placed on the surface of a long strip-shaped release liner 14 at appropriate intervals. Several pieces are temporarily attached. Although the label continuum 10 shown in FIG. 3 is a label continuum in which labels are arranged in one row, the number of labels may be two or more rows. Note that the shape of the label is not limited to a rectangle, and may be any appropriate shape such as a polygon, circle, or ellipse depending on the use of the label.

[Emulsion type adhesive composition]
The adhesive layer of the adhesive sheet for labels of the present invention is formed from an emulsion-type adhesive composition containing an emulsion-type adhesive and an emulsion-type tackifier.
Hereinafter, the emulsion type adhesive and the emulsion type tackifier will be explained in detail.

<Emulsion type adhesive>
An emulsion-type adhesive is a water-based adhesive made by emulsifying a polymer and dispersing it in water. For example, emulsion-type adhesives using acrylic emulsions, natural rubber latex, synthetic rubber latex, etc. as adhesive bases are well-known. It is being
Among these, it is preferable to use an acrylic emulsion type adhesive using an acrylic emulsion as an adhesive base.
In one aspect of the present invention, the content of the acrylic emulsion type adhesive is preferably 70 to 100% by mass, more preferably 70% to 100% by mass, based on the total amount of the emulsion type adhesive, from the viewpoint of making it easier to exhibit the effects of the present invention. is 80 to 100% by weight, more preferably 90 to 100% by weight, even more preferably 95 to 100% by weight, even more preferably 100% by weight.
The acrylic emulsion type adhesive will be explained in detail below.

(Acrylic emulsion type adhesive)
The acrylic emulsion type adhesive is a (meth)acrylic acid ester polymer obtained by polymerizing an ester monomer of (meth)acrylic acid and an alkyl alcohol whose alkyl group has 1 to 18 carbon atoms. is an adhesive whose main component is dispersed in water.
In this specification, "(meth)acrylic" means "acrylic or methacrylic", and the same applies to other similar terms. For example, "(meth)acrylic ester" means "acrylic ester or methacrylic ester."
Furthermore, in this specification, the term "main component" refers to a component whose content exceeds 50% by mass based on the total amount of the constituent components.

Examples of ester monomers of (meth)acrylic acid and alkyl alcohols whose alkyl groups have 1 to 18 carbon atoms include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and acrylic acid. selected from 2-ethylhexyl acid, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, etc. One or more types may be mentioned.
Among these, it is preferable to use at least one of n-butyl acrylate and 2-ethylhexyl acrylate as the main component.
In one aspect of the present invention, the total content of the ester monomers n-butyl acrylate and 2-ethylhexyl acrylate is preferably 70 ~100% by weight, more preferably 80~100% by weight, still more preferably 90~100% by weight, even more preferably 95~100% by weight.

Here, the (meth)acrylic acid ester polymer may be copolymerized with a vinyl monomer that is copolymerizable with the ester monomer.
However, it is preferable that the vinyl monomer is copolymerized in a proportion of 20 parts by mass or less with respect to 100 parts by mass of the ester monomer, and the vinyl monomer is copolymerized in a proportion of 10 parts by mass or less. It is more preferable that the vinyl monomer is copolymerized in a proportion of 5 parts by mass or less.

Examples of the vinyl monomer copolymerizable with the ester monomer include vinyl group-containing monomers such as styrene, α-methylstyrene, vinyltoluene, vinyl acetate, acrylonitrile, glycidyl acrylate, and glycidyl methacrylate. ; Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxy methacrylate Hydroxyl group-containing monomers such as propyl; nitrogen-containing monomers such as acrylamide, N-methylolacrylamide, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, and vinylpyrrolidone; and the like.
Among these, carboxyl group-containing monomers are preferred, and acrylic acid is more preferred.

The ester monomer or the ester monomer and the vinyl monomer are polymerized or copolymerized using a polymerization initiator. Here, water also acts as a dispersion medium, and the (meth)acrylic ester polymer or (meth)acrylic ester copolymer obtained by polymerization or copolymerization is dispersed by the surfactant. By dispersing these in water, an acrylic emulsion type adhesive is produced.

The surfactant can be appropriately selected from conventionally known anionic, nonionic, and cationic emulsifiers and synthetic polymer emulsifiers.
Among these, from the viewpoint of improving water-resistant adhesive strength, it is preferable to use a reactive emulsifier. Note that the term "reactive emulsifier" refers to an emulsifier that has a reactive functional group in its molecule, and means an emulsifier that can chemically bond to the polymer in the micelles during the process of emulsion polymerization.

Examples of the reactive emulsifier include one or more compounds selected from compounds having structures represented by the following general formulas (I) to (VII).

In addition, in the above general formulas (I) to (VII), R ¹ is an alkyl group, R ² is a hydrogen atom or a methyl group, R ³ is an alkylene group, and X is a hydrogen atom or a sulfonic acid group. shows. Further, n, m, and k are integers of 1 or more, and m+k=3.

Specific examples of reactive emulsifiers include Adecaria Soap SE-20N (anionic type), Adekaria Soap SE-10N (anionic type), and Adekaria Soap NE-10 (nonionic type) manufactured by Asahi Denka Co., Ltd. as commercially available products. ), Adekaria Soap NE-20 (nonionic), Adekaria Soap NE-30 (nonionic), Adekaria Soap NE-40 (nonionic), Adekaria Soap SDX-730 (anionic), and Adekaria Soap SDX-731 (anionic type), Eleminol JS-2 (anionic type) and Eleminol RS-30 (anionic type) manufactured by Sanyo Kasei Co., Ltd., Latemul S-180A (anionic type) and Latemul S-180 manufactured by Kao Corporation. (anionic type), Aqualon BC-05 (anionic type), Aqualon BC-10 (anionic type), Aqualon BC-20 (anionic type), Aqualon HS-05 (anionic type), Aqualon HS-05 (anionic type) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. HS-10 (anionic), Aqualon HS-20 (anionic), Aqualon RN-10 (nonionic), Aqualon RN-20 (nonionic), Aqualon RN-30 (nonionic), Aqualon RN-50 (nonionic) Examples include New Frontier S-510 (anionic type), New Frontier A-229E (anionic type), and Phosphinol TX (anionic type) manufactured by Toho Chemical Industry Co., Ltd.
These may be used alone or in combination of two or more.

The amount of the reactive emulsifier used is usually 0.5 to 4.5 parts by weight per 100 parts by weight of the ester monomer or 100 parts by weight of the ester monomer and the vinyl monomer. The amount is preferably 0.5 to 3.0 parts by weight, more preferably 0.5 to 2.0 parts by weight.

Examples of the polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; peroxides such as hydrogen peroxide, cumene hydroperoxide, and t-butyl hydroperoxide; azobisisobutyronitrile; used. In addition, when polymerizing at a relatively low temperature, it is also possible to carry out redox polymerization using a reducing agent such as sodium thiosulfate, sodium bisulfite, and sodium pyrophosphate.

In addition, in the polymerization or copolymerization of the ester monomer or the ester monomer and the vinyl monomer, at least one of a chain transfer agent and a molecular weight regulator is used to adjust the molecular weight of the polymer. It's okay.
Examples of the chain transfer agent include dodecyl mercaptan and lauryl mercaptan.
Furthermore, examples of molecular weight modifiers include α-methylstyrene dimer and the like.

Here, from the viewpoint of stabilizing the produced acrylic emulsion adhesive, a protective colloid may be added to the acrylic emulsion adhesive.
As the protective colloid, water-soluble polymer compounds such as polyvinyl alcohol, polyvinyl alcohol derivatives, carboxymethyl cellulose, and cellulose derivatives such as hydroxyethyl cellulose are used.

Further, a crosslinking agent may be added to the acrylic emulsion type adhesive, if necessary. Examples of the crosslinking agent include epoxy compounds, carbodiimide compounds, oxazoline compounds, hydrazide compounds, isocyanate compounds, aziridine compounds, alkoxysilane compounds, amine compounds, and metal chelate compounds.

<Emulsion type tackifier>
An emulsion type tackifier is a water-based tackifier in which a tackifying resin is emulsified and dispersed in water.
The tackifier resin includes one or more selected from rosin resins and terpene resins.
When the tackifier resin constituting the emulsion type tackifier contains one or more selected from plant-derived resins such as rosin resin and terpene resin, the degree of biomass of the adhesive layer is improved. Therefore, it is possible to provide a pressure-sensitive adhesive sheet in which the degree of biomass in the pressure-sensitive adhesive layer is increased.
In addition, in one aspect of the present invention, the tackifying resin may include a tackifying resin other than the rosin resin and the terpene resin (for example, petroleum resin, etc.). However, from the viewpoint of making it easier to exhibit the effects of the present invention, the total content of rosin resin and terpene resin is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, based on the total amount of tackifier resin. , more preferably 90 to 100% by weight, even more preferably 95 to 100% by weight, even more preferably 100% by weight.
The rosin resin and terpene resin will be explained in detail below.

(rosin resin)
Examples of the rosin resin include unmodified rosin such as gum rosin, wood rosin, and tall oil rosin; unmodified rosin modified by one or more treatments selected from hydrogenation, disproportionation, polymerization, chemical modification, etc. modified rosin; various rosin derivatives, etc.
Rosin derivatives include, for example, rosin esters obtained by esterifying unmodified rosin or modified rosin with alcohol; unsaturated fatty acid-modified rosins obtained by modifying unmodified rosin or modified rosin with unsaturated fatty acids; unsaturated rosin esters. Unsaturated fatty acid-modified rosin esters modified with fatty acids; unmodified rosin, modified rosin, unsaturated fatty acid-modified rosins, or rosin alcohols obtained by reducing the carboxy group in unsaturated fatty acid-modified rosin esters; unmodified rosin, modified Metal salts of rosins (especially rosin esters) such as rosin and various rosin derivatives; rosin obtained by adding phenol to rosins such as unmodified rosin, modified rosin, and various rosin derivatives with an acid catalyst and thermally polymerizing the mixture. Phenolic resin; Acid-modified rosins made by modifying unmodified rosin or modified rosin with acids such as acrylic acid, fumaric acid, or maleic acid; Rosin esters modified with acids such as acrylic acid, fumaric acid, or maleic acid. and acid-modified rosin esters.
These may be used alone or in combination of two or more.

Here, in one aspect of the present invention, from the viewpoint of making it easier to exhibit the effects of the present invention, the tackifying resin may include one or more types selected from rosin resins having a softening point of 80° C. or higher and 170° C. or lower. is preferred. Here, the total content of the rosin resin is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and Preferably it is 90 to 100% by weight, even more preferably 95 to 100% by weight, even more preferably 100% by weight.
In addition, from the viewpoint of further improving the tack on polyolefin and further suppressing zipping, the softening point of the rosin resin is preferably 80°C or more and 150°C or less, and preferably 90°C or more and 140°C or less. is more preferable, 90°C or more and 130°C or less, even more preferably 90°C or more and 125°C or less, even more preferably 90°C or more and 120°C or less, 90°C or more and 115°C It is more preferable that the temperature is below, and even more preferably that it is 90°C or more and 110°C or less.
In addition, from the viewpoint of further improving the adhesion to curved surfaces, the softening point of the rosin resin is preferably higher than 85°C, more preferably 90°C or higher.
The softening point of the rosin resin can be adjusted, for example, by the degree of polymerization of the rosin, the mixing ratio of the polymerized rosin and the rosin monomer, and the like.
Specifically, the higher the polymerization degree of rosin, the higher the softening point of the rosin resin, and conversely, the lower the polymerization degree of rosin, the lower the softening point.
Furthermore, the higher the proportion of polymerized rosin in the total amount of polymerized rosin and rosin monomer, the higher the softening point of the rosin resin, and conversely, the lower the proportion of polymerized rosin, the lower the softening point.
In addition, in this specification, the softening point of a tackifier resin means the value measured based on the ring and ball method based on JIS K2207:2006.

Note that the rosin resin is preferably esterified from the viewpoint of stability. That is, the rosin resin is preferably an ester produced by esterifying unmodified rosin or modified rosin.
Examples of the alcohol used for esterification include dihydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, and 1,6-hexanediol; trihydric alcohols such as glycerin, trimethylolpropane, and trimethylolethane. ; Tetrahydric alcohols such as pentaerythritol and diglycerin; Hexahydric alcohols such as dipentaerythritol; and amino alcohols such as triethanolamine, tripropanolamine, triisopropanolamine, N-isobutyldiethanolamine, and Nn-butyldiethanolamine. etc.
These may be used alone or in combination of two or more.

Here, in one aspect of the present invention, the content of rosin resin with a softening point of 50° C. or lower is low in order to suppress seepage of glue from the side of the label and contamination of the punching blade during punching. is preferred. Specifically, the content of the rosin resin with a softening point of 50° C. or lower is preferably less than 20% by mass, more preferably less than 10% by mass, and even more preferably less than 5% by mass, based on the total amount of the tackifying resin. Even more preferably, it does not contain less than 1% by mass, and still more preferably does not contain a rosin resin having a softening point of 50° C. or lower.

(terpene resin)
Terpene resins include unmodified terpene polymers such as α-pinene polymer, β-pinene polymer, and limonene polymer; terpene polymers can be modified with phenol modification, aromatic modification, hydrogenation modification, hydrocarbon modification, etc. Examples include modified terpene polymers modified by one or more selected treatments. Examples of modified terpene polymers include terpene phenol resins and aromatic modified terpene resins.
These may be used alone or in combination of two or more.

Note that the unmodified terpene polymer is a polymer produced by cationically polymerizing one or more monoterpenes selected from α-pinene, β-pinene, and limonene in the presence of a catalyst. In addition, instead of monoterpene, it is also possible to use a polymer produced by cationically polymerizing other terpenes such as diterpene as the tackifying resin.

Note that terpene phenol resin is a resin produced by condensing terpene with phenol, formalin, and the like. The aromatic modified terpene resin is a resin produced by copolymerizing a terpene monomer and an aromatic monomer, or a resin in which a six-membered carbon ring present in a terpene is modified with a benzene ring.

Here, in one aspect of the present invention, the content of terpene resin with a softening point of 50° C. or lower is low in order to suppress seepage of glue from the side of the label and contamination of the punching blade during punching. is preferred. Specifically, the content of the terpene resin with a softening point of 50 ° C. or less is preferably less than 20% by mass, more preferably less than 10% by mass, even more preferably less than 5% by mass, based on the total amount of the tackifying resin. Even more preferably, it does not contain less than 1% by mass, and still more preferably does not contain a terpene resin having a softening point of 50° C. or lower.
Examples of the terpene resin having a softening point of 50° C. or lower include unmodified terpene polymers.

(Content ratio of rosin resin and terpene resin)
In one aspect of the present invention, from the viewpoint of making it easier to exhibit the effects of the present invention, the content ratio of rosin resin and terpene resin [(rosin resin)/(terpene resin)] is preferably 30 in terms of mass ratio. /70 to 100/0, more preferably 50/50 to 100/0, even more preferably 70/30 to 100/0, even more preferably 80/20 to 100/0, even more preferably more than 80/20 100/0, more preferably 90/10 to 100/0, even more preferably 95/5 to 100/0, even more preferably 100/0.

(Preparation of emulsion type tackifier)
Emulsion-type tackifiers are prepared by emulsifying tackifying resins.
Here, when preparing an emulsion-type tackifier using a plurality of tackifier resins, each of the plurality of tackifier resins may be separately emulsified (hereinafter also referred to as "single emulsification"), A mixed resin obtained by melt-mixing or melt-mixing a plurality of tackifying resins may be emulsified (hereinafter also referred to as "mixed emulsification").

In addition, "melt mixing" means mixing a plurality of tackifier resins while heating and melting them.
Moreover, "dissolution mixing" means dissolving a plurality of tackifying resins in a solvent and mixing them as a mixed solution.
Any conventionally known method may be applied to such melt mixing or melt mixing.

As the emulsifier for emulsifying the tackifying resin, conventionally known emulsifiers can be used. For example, it is possible to use one or more of anionic, nonionic, and cationic emulsifiers and synthetic polymer emulsifiers. However, it is preferable to use at least one of anionic and nonionic emulsifiers.

The amount of emulsifier used is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the tackifying resin, from the viewpoint of improving the water resistance of the adhesive layer.

Note that a conventionally known emulsification method can be applied to emulsify the tackifier resin. For example, a solvent-based emulsification method, a solvent-free emulsification method, a phase inversion emulsification method, etc. are applied.

"Solvent-based emulsification method" refers to the first step of dissolving the tackifying resin in an organic solvent, and premixing emulsified water, which is an emulsifier mixed with water, into the solution obtained in the first step, thereby reducing coarse particles. A second step of producing an aqueous emulsion, a third step of finely emulsifying the coarse aqueous emulsion, and removing the organic solvent used as a solvent in the first step from the finely emulsified aqueous emulsion under normal pressure or reduced pressure. In this method, emulsification is carried out by a fourth step.

Note that examples of the organic solvent in the first step include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ketone and methyl isobutyl ketone, and chlorinated hydrocarbon solvents such as methylene chloride.

Further, the fine emulsification in the third step is performed using a mixer, a colloid mill, a high-pressure emulsifier, a high-pressure discharge emulsifier, a high-shear emulsifier, and the like. In addition, from the viewpoint of adjusting the viscosity to an appropriate range and improving the storage stability and mechanical stability of the emulsion, the average particle diameter of the aqueous emulsion of the tackifying resin is 0.10 to 0.50 μm by fine emulsification. It is preferable to adjust it to .

"Solvent-free emulsification method" refers to the first step of melting the tackifying resin under normal pressure or pressure, and the pre-mixing of emulsified water prepared by mixing an emulsifier with water to the tackifying resin melted in the first step. In this method, emulsification is carried out through a second step of producing a coarse-grained aqueous emulsion, and a third step of fine-emulsifying the coarse-grained aqueous emulsion.

“Phase inversion emulsification method” is classified into “solvent type” and “solvent-free type”.
The "solvent type" phase inversion emulsification method involves the first step of dissolving the tackifying resin in an organic solvent, and gradually adding emulsified water containing an emulsifier to water while stirring the solution obtained in the first step. In addition, a second step of producing a water-in-oil emulsion, a third step of phase inverting the water-in-oil emulsion to an oil-in-water emulsion, and a first step from the oil-in-water emulsion under normal pressure or reduced pressure. In this method, emulsification is carried out through a fourth step of removing the organic solvent used as a solvent.
The "solvent-free" phase inversion emulsification method involves the first step of melting the tackifier resin under normal pressure or pressure. In addition, the emulsification is carried out by a second step of producing a water-in-oil emulsion, and a third step of inverting the water-in-oil emulsion into an oil-in-water emulsion.

Here, a commercially available product may be used as the emulsion type tackifier. To give specific examples, examples of emulsion-type tackifiers whose tackifying resin is rosin resin include Super Ester E-720, Super Ester E-730-55, Super Ester E-788, and Super Ester E-788 manufactured by Arakawa Chemical Co., Ltd. Ester E-900-NT, Super Ester E-910NT, Super Ester E-865, Super Ester E-865-NT, Super Ester NS-100H, and Super Ester NS-121, and Harie manufactured by Harima Kasei Group Co., Ltd. Examples include Star SK-370N and Harrier Star SK-218NS. Examples of emulsion-type tackifiers in which the tackifying resin is a terpene resin include Tamanol E-100, Tamanol E-300-NT, and Tamanol E-200-NT manufactured by Arakawa Chemical Industries, Ltd.
These may be used alone or in combination of two or more.

<Blending ratio of emulsion type tackifier to emulsion type adhesive>
In one aspect of the present invention, the emulsion-type adhesive composition used in the adhesive layer of the adhesive sheet for labels is composed of an emulsion-type tackifier (solid content) based on 100 parts by mass (solid content) of the emulsion-type adhesive. It is preferable to prepare by adding 3.0 parts by mass or more and less than 33.0 parts by mass.
When the emulsion type tackifier (solid content) is less than 3.0 parts by mass with respect to 100 parts by mass (solid content) of the emulsion type adhesive composition, the adhesive layer formed by the emulsion type adhesive composition is Adhesive strength to polyolefins is not sufficiently secured, and adhesion to curved surfaces is also poor.
In addition, when the emulsion type tackifier (solid content) is 33.0 parts by mass or more with respect to 100 parts by mass (solid content) of the emulsion type adhesive composition, the adhesive layer formed by the emulsion type adhesive composition is inferior in adhesion to curved surfaces.
When the emulsion type tackifier (solid content) is 3.0 parts by mass or more and less than 33.0 parts by mass with respect to 100 parts by mass (solid content) of the emulsion type adhesive, the biomass degree of the adhesive layer is 2.0 parts by mass or more. Adjusted to 9% or more and less than 24.8%, it can exhibit sufficient adhesive strength even to polyolefins, has excellent adhesion to curved surfaces, and has sufficient tack to polyolefins. It can also be used as an adhesive sheet for labels with an increased biomass content.
Here, in one aspect of the present invention, from the viewpoint of making it easier to exhibit the effects of the present invention, the emulsion-type tackifier (solid content) is preferably added to 100 parts by mass (solid content) of the emulsion-type adhesive. is 3.0 parts by mass or more and 25.0 parts by mass or less, more preferably 3.0 parts by mass or more and 23.0 parts by mass or less.
Furthermore, in one aspect of the present invention, from the viewpoint of making it easier to improve the tack on polyolefin, the emulsion-type tackifier (solid content) is preferably 3 parts by mass (solid content) per 100 parts by mass (solid content) of the emulsion-type adhesive. The amount is .0 parts by mass or more and 17.6 parts by mass or less, more preferably 3.0 parts by mass or more and 13.0 parts by mass or less.

<Base material>
Next, the base material included in the adhesive sheet for labels of the present invention will be explained.
Examples of the base material included in the adhesive sheet for labels of the present invention include papers, synthetic papers, synthetic resin films, and the like.
In addition, a single layer may be sufficient as a base material, and the multilayer which laminated|stacked two or more may be sufficient as it.

Papers used as the base material include wood-free paper, art paper, coated paper, cast coated paper, foil paper, thermal paper, thermal transfer paper, and the like.

Examples of the synthetic paper used as the base material include synthetic papers made of resins such as polypropylene, polystyrene, polyethylene, and polyester.
Here, as the synthetic paper, commercially available products may be used, such as "CRISPR (registered trademark)" manufactured by Toyobo Co., Ltd. and "YUPO (registered trademark)" manufactured by Yupo Corporation.

Examples of the resin constituting the synthetic resin film used as the base material include polyolefin resins such as polyethylene and polypropylene; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer. Vinyl resins such as polymers; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic modified polyurethane; Polymethylpentene; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins; acrylic resins; fluororesins and the like.
Among these, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, and acrylonitrile-butadiene-styrene copolymer are preferred.
When a synthetic resin film is used as a base material, from the viewpoint of improving adhesion with the adhesive layer, the surface of the synthetic resin film constituting the base material is subjected to surface treatment using a corona treatment method or the like, or with a primer. Layers may be provided.
Furthermore, a metallic gloss layer such as aluminum vapor deposition or tin vapor deposition may be provided on either side of the synthetic resin film.

The synthetic resin film may further contain various additives such as ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, anti-blocking agents, fillers, and colorants. .

The thickness of the base material is appropriately set depending on the application, but is preferably 5 to 1000 μm, more preferably 10 to 700 μm, still more preferably 20 to 500 μm, and even more preferably 30 to 300 μm.

Note that in the pressure-sensitive adhesive sheet for labels according to one embodiment of the present invention, from the viewpoint of improving adhesion of ink, etc. during printing, an easy-adhesion layer, etc. is further added on the surface of the base material opposite to the pressure-sensitive adhesive layer. It may have. Furthermore, the printing method for the adhesive sheet for labels according to one embodiment of the present invention is not particularly limited, and examples include flexo printing, gravure printing, offset printing, screen printing, inkjet printing, digital printing, and laser printing.

<Various physical properties of adhesive sheets for labels>
(Room temperature adhesion to stainless steel)
The pressure-sensitive adhesive sheet of one embodiment of the present invention has a room-temperature adhesive strength to stainless steel (SUS304 steel plate, No. 360 polished) measured by the method described in the Examples described later, preferably 5.0 N/25 mm or more, more preferably 6. .0N/25mm or more, more preferably 6.5N/25mm or more. Moreover, it is usually 15N/25mm or less.

(Room temperature adhesion to polyolefin)
The pressure-sensitive adhesive sheet of one embodiment of the present invention has a room-temperature adhesive force to polyolefin (polyethylene plate) measured by the method described in the Examples described below, preferably 3.0 N/25 mm or more, more preferably 4.0 N/25 mm or more. , more preferably 4.5N/25mm or more. Moreover, it is usually 10N/25mm or less.

(Tack measurement value in loop tack test)
The pressure-sensitive adhesive sheet of one embodiment of the present invention has a tack measurement value in a loop tack test on polyolefin (polyethylene plate) measured by the method described in the Examples below, preferably 1.0 N/25 mm or more, more preferably 2.0 N/25 mm or more. 0 N/25 mm or more, more preferably 3.0 N/25 mm or more, even more preferably 4.0 N/25 mm or more, even more preferably 4.7 N/25 mm or more. Moreover, it is usually 10N/25mm or less.

(Curved surface adhesion)
The pressure-sensitive adhesive sheet of one aspect of the present invention has curved surface adhesion (length from the end of the pressure-sensitive adhesive sheet peeled off from the polyethylene round bar) measured by the method described in the Examples described later, preferably 1.5 mm or less. More preferably it is 1.0 mm or less, still more preferably 0.5 mm or less.

<Production method of adhesive sheet for labels>
Although the method for producing the adhesive sheet for labels of the present invention is not particularly limited, for example, the adhesive layer is formed by coating the above-mentioned emulsion type adhesive composition on a base material. Conventional methods such as roll coating, knife coating, bar coating, gravure coating, die coating, curtain coating, etc. can be applied to apply the emulsion-type adhesive composition to the base sheet. It is possible.
The thickness of the adhesive layer is usually in the range of 5 to 100 μm, preferably 10 to 60 μm.

In one aspect of the method for producing a pressure-sensitive adhesive sheet for labels of the present invention, it is preferable to provide a release liner on the pressure-sensitive adhesive layer thus formed. Examples of release liners include high-density base paper such as glassine paper, laminated paper such as clay coated paper, kraft paper, and high-quality paper laminated with polyethylene resin, or plastic films such as polyethylene terephthalate, polyethylene naphthalate, and polyolefin. Another example is one in which a release agent such as fluororesin or silicone is applied to a dry weight of about 0.1 to 3 g/m ² and a release layer is provided by heat curing or ultraviolet curing. There are no particular restrictions on the thickness of the release liner, but it is usually in the range of 25 to 200 μm.
In addition, as another embodiment of the method for producing a pressure-sensitive adhesive sheet for labels of the present invention, for example, the above-mentioned emulsion-type pressure-sensitive adhesive composition is applied to a release liner to form a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer and base material A pressure-sensitive adhesive sheet for labels having a laminated structure in which a base material, an adhesive layer, and a release liner are laminated in this order may be manufactured by laminating them together.

Next, one aspect of the method for manufacturing the continuous label body shown in FIG. 3 will be described.
First, an adhesive layer and a base material are laminated on the surface of a long strip-shaped release liner to prepare a roll-shaped original fabric of a continuous label body. The method of laminating each layer is as described above.
When it is necessary to print on the label side, this roll-shaped original fabric is set in a printing machine, and printing is performed on the base material side while the label is being fed out.
Next, the base material and the adhesive layer are punched out using a die-cutting tool such as a rotary die-cutting unit, and unnecessary parts of the base material and the adhesive layer that will not become a label are removed.
In this way, a continuous label body is manufactured in which a plurality of labels are temporarily attached to the surface of a long strip-shaped release liner at predetermined intervals in the flow direction. At this time, as in the embodiment described above, if the content of the tackifying resin with a softening point of 50°C or less is small, the seepage of glue from the side of the label and the contamination of the punching blade during punching can be suppressed. can do.

<Applications of adhesive sheet for labels>
The adhesive sheet for labels of the present invention can exhibit sufficient adhesion to polyolefin, has excellent adhesion to curved surfaces, and has sufficient tack to polyolefin. is also elevated. Therefore, even if the adherend is a polyolefin container or package having a curved surface, it can be firmly attached. Furthermore, it becomes possible to instantly attach a label to a polyolefin adherend using a labeling machine. Thereby, the speed of the process of attaching a label to an adherend can be increased, and productivity can be improved. Moreover, by incorporating plant-derived components into the adhesive layer, the degree of biomass of the adhesive layer is increased, and the amount of fossil resource-based materials used is relatively reduced. Therefore, we have increased the proportion of carbon-neutral materials in the adhesive layer that do not substantially increase atmospheric carbon dioxide during incineration, etc. The proportion of materials that are difficult to recycle can be reduced. Therefore, it also has the advantage of being able to reduce emissions of carbon dioxide, which is a greenhouse gas, during incineration and the like.
Furthermore, since it has an adhesive layer formed from an emulsion-type adhesive composition, it is also excellent in terms of safety, hygiene, and environment.
Therefore, the adhesive sheet for labels of the present invention is suitable for curved surfaces such as food containers (e.g. egg cases) and packaging, stationery, cosmetic containers, kitchen utensil containers, bathroom utensil containers, etc. It can be suitably used as a display label or an eye-catching label (attention sticker, pop label, pop sheet, etc.) for a wearer. Further, the adhesive sheet for labels of the present invention can be suitably used as labels for office automation equipment, price tag stickers, labels for transportation cardboard, labels for electronic equipment, logistics management labels, etc.

The present invention will be specifically explained with reference to the following examples, but the present invention is not limited to the following examples.

[Method of measuring physical property values]
The physical property values in this example are values measured by the following method.

(1) Measurement of the thickness of each layer The thickness was measured using a constant pressure thickness measuring device manufactured by Techlock Co., Ltd. (model number: "PG-02J", standard specifications: JIS K6783, Z1702, Z1709 compliant).

[Examples 1 to 7 and Comparative Examples 1 to 2]
Adhesive sheets of Examples 1 to 7 and Comparative Examples 1 to 2 were produced according to the procedure described below.
The emulsion type tackifier used in Examples 1 to 7 and Comparative Example 2 is shown below.
(Emulsion type tackifier)
・Emulsion type tackifier 1: Product name "Hariestar", product number "SK-218NS", manufactured by Harima Kasei Group Co., Ltd., tackifier resin: rosin resin, softening point of tackifier resin: 100°C
・Emulsion-type tackifier 2: Product name "Super Ester", product number "E-730-55", manufactured by Arakawa Chemical Industry Co., Ltd., tackifier resin: rosin resin, softening point of tackifier resin: 125°C
・Emulsion-type tackifier 3: Product name "Super Ester", product number "E-788", manufactured by Arakawa Chemical Industry Co., Ltd., tackifier resin: rosin resin, softening point of tackifier resin: 160°C

<Example 1>
(1) Production of emulsion-type adhesive For production of emulsion-type adhesive, a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel was used. In a reaction vessel, 55 parts by mass of ion-exchanged water was heated to 80° C. with stirring. Then, when the temperature of the ion-exchanged water reached 80° C., 0.1 part by mass of ammonium persulfate was added as a polymerization initiator to prepare an aqueous ammonium persulfate solution.
In addition to the ammonium persulfate aqueous solution, 60 parts by mass of 2-ethylhexyl acrylate, 38 parts by mass of butyl acrylate, and 2 parts by mass of acrylic acid, and an anionic reactive emulsifier (product name "New Frontier A-229E", 1 part by mass (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), an appropriate amount of 25% ammonium water for neutralization, and 0.4 parts by mass of ammonium persulfate are added to 43 parts by mass of ion-exchanged water and stirred with a mixer, I got the pre-emulsion.
Next, the pre-emulsion was added dropwise to the ammonium persulfate aqueous solution over 2 hours while maintaining the temperature inside the reaction vessel at 80°C. Then, 1 part by mass of persulfuric acid was added at 1 hour and 2 hours after the completion of dropping the pre-emulsion to complete the polymerization reaction, thereby producing an acrylic emulsion pressure-sensitive adhesive.

(2) Preparation of emulsion-type adhesive composition The acrylic emulsion-type adhesive produced in the above (1) and emulsion-type tackifiers 1, 2, and 3 are mixed in the amounts shown in Table 1, An emulsion type adhesive composition was prepared.
The amounts of the acrylic emulsion-type adhesive and emulsion-type tackifier shown in Table 1 refer to the amounts in terms of solid content.

(3) Preparation of adhesive sheet The emulsion-type adhesive composition obtained in (2) above is applied onto glassine release paper with a thickness of 70 μm so that the thickness of the adhesive layer after drying is 25 μm. did.
After coating, it was dried at 90° C. for 1 minute, and then bonded to polypropylene synthetic paper (product name “SGP80”, manufactured by Yupo Corporation, thickness: 80 μm) to produce an adhesive sheet.

<Example 2>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that the amount of emulsion-type tackifier 1 was increased to 20.0 parts by mass.

<Example 3>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that emulsion-type tackifier 1 was not blended and the amount of emulsion-type tackifier 2 was increased to 10.5 parts by mass.

<Example 4>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that emulsion-type tackifier 1 was not blended and the amount of emulsion-type tackifier 2 was increased to 20.5 parts by mass.

<Example 5>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that emulsion-type tackifier 1 was not blended and the amount of emulsion-type tackifier 3 was increased to 12.5 parts by mass.

<Example 6>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that emulsion-type tackifier 1 was not blended and the amount of emulsion-type tackifier 3 was increased to 22.5 parts by mass.

<Example 7>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that emulsion-type tackifier 1 was not blended.

<Comparative example 1>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that none of emulsion-type tackifiers 1, 2, and 3 were blended.

<Comparative example 2>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that the amount of emulsion-type tackifier 1 was increased to 30 parts by mass.

[evaluation]
The pressure-sensitive adhesive sheets of Examples 1 to 7 and Comparative Examples 1 to 2 were evaluated for room temperature adhesive strength, loop tack, and curved surface adhesion.

(1) Adhesive strength at room temperature The adhesive sheet was cut into 25 mm x 300 mm to prepare test pieces.
The release liner was peeled off from the test piece, and the sample was attached to an adherend at 23° C. and 50% RH. The pressure bonding was performed by making one reciprocation with a roller having a mass of 2000 g. The adherend was a stainless steel plate (SUS304 steel plate, No. 360 polished) or a polyethylene plate.
Immediately after applying the adhesive sheet to the adherend, the peel strength was measured when the adhesive sheet was peeled from the adherend in a 180° direction at a speed of 300 mm/min in an environment of 23°C and 50% RH. This was measured and taken as the room temperature adhesive strength.
The test conditions were based on JIS Z0237:2009.

(2) Loop tack test The adhesive sheet was cut into 25 mm x 300 mm (including 25 mm gripping portions at both ends) to prepare test pieces. Next, the release liner of the test piece was peeled off, the measurement surface (adhesive layer surface) was turned outward, and the base material surfaces at both ends were in contact with each other to form a loop shape. The loop-shaped test piece was suspended by holding the grips at both ends between the upper grips of the machine.
Next, after placing the polyethylene plate as the adherend horizontally on the lower grip of the tensile testing machine, the upper grip was lowered until the distance from the upper grip to the polyethylene plate was 60 mm, and after 15 seconds, the upper grip was lowered. The sample was pulled up at a rate of 300 mm/min, and the peak value of the peel strength at that time was taken as the loop tack value.
Note that the loop tack test was conducted at 23° C. and in a 50% RH environment.

(3) Adhesiveness to curved surfaces A polypropylene laminating adhesive film ( A pressure-sensitive adhesive sheet for testing was prepared by applying a polypropylene layer (thickness: 20 μm) to a curved surface under conditions in which lifting was more likely to occur.
Then, the adhesive sheet for the test was made 25 mm wide and cut into a polyethylene round bar with a diameter of 10 mm so that 7/10 of the circumference was covered (length of the adhesive sheet for the test: 10 mm x π x 7 /10=22mm), after pasting at 23℃ and 50%RH environment, after leaving it for 3 days at 60℃ and 50%RH environment (from the edge of the adhesive sheet peeled off from the polyethylene round bar) Length: one side) was measured.

The results are shown in Table 1.

From the results shown in Table 1, the following can be seen.
It can be seen that the adhesive sheets of Examples 1 to 7 have excellent room temperature adhesion not only to metals such as stainless steel but also to polyolefins such as polyethylene plates. Furthermore, it can be seen that not only excellent adhesion to curved surfaces can be achieved, but also a sufficient loop tack value when using a polyethylene plate, and sufficient tack for polyolefins. Moreover, the tackifier resin of the emulsion type tackifier is a plant-derived resin, and the degree of biomass of the adhesive layer can be increased.
On the other hand, when an emulsion-type tackifier is not used as in Comparative Example 1, it can be seen that the adhesive strength at room temperature to stainless steel and the adhesive strength at room temperature to polyethylene are inferior, and the adhesion to curved surfaces is also significantly inferior.
Further, it can be seen that when the biomass degree of the adhesive layer is 24.8% or more as in Comparative Example 2, the adhesion to curved surfaces is significantly inferior.

1 Adhesive sheet for labels 2 Base material 3 Adhesive layer 4 Release liner

Claims (5)

At least comprising a base material and an adhesive layer provided on one side of the base material,
The adhesive layer is formed from an emulsion-type adhesive composition containing an emulsion-type adhesive and an emulsion-type tackifier,
The emulsion type adhesive includes an acrylic emulsion type adhesive,
The tackifier resin of the emulsion type tackifier includes two or more selected from rosin resins ,
The two or more rosin resins include a rosin resin with a softening point of 90°C or more and 110°C or less,
A pressure-sensitive adhesive sheet for labels, wherein the pressure-sensitive adhesive layer has a biomass degree of 11.5% or more and less than 24.8%. The adhesive sheet for labels according to claim 1, wherein the adhesive layer has a biomass degree of 11.5% or more and 20.0% or less. The adhesive sheet for labels according to claim 1 or 2, wherein the content of the acrylic emulsion type adhesive is 95 to 100% by mass based on the total amount of the emulsion type adhesive. The pressure-sensitive adhesive sheet for labels according to any one of claims 1 to 3, wherein the total content of the rosin resin is 95 to 100% by mass based on the total amount of the tackifier resin. The adhesive sheet for labels according to any one of claims 1 to 4, which is used as a punched label.