JP6775073B2 - Alkaline dispersion type hot melt adhesive - Google Patents

Description

The present invention relates to an alkali-dispersed hot-melt adhesive, and particularly adheres to labels such as glass bottles and PET (polyethylene terephthalate) bottles used in soft drinks, seasonings, detergents, shampoos, cooking oils, cosmetics, pharmaceuticals, etc. The present invention relates to an alkali-dispersed hot melt adhesive suitable as an agent.

As containers for medicines and beverages, aluminum cans, glass bottles, and polyethylene terephthalate (PET) bottles are generally widely distributed. Labels are attached to the surface of these containers with a strength that cannot be peeled off by hand with an adhesive. As a label for a beverage container, a polyethylene terephthalate (PET) film, a biaxially stretched polypropylene film (OPP), and a polylactic acid (PLA) film, a body-wrapping label (roll label), are often used.

When reusing a labeled container, it is necessary to collect the used container at the factory, immerse the container in a heated alkaline aqueous solution, and separate the label from the container. Therefore, the pressure-sensitive adhesive applied to the label for a container is required to have the property of peeling the label from the container in a short time (alkali dispersibility) by swelling, softening, dispersing, or dissolving in an alkaline aqueous solution.

Patent Documents 1 and 2 disclose a hot melt adhesive for easily peeling a label from a PET bottle. The hot melt adhesives described in these documents are alkali-dispersed hot melt adhesives containing a styrene block copolymer and a tackifier resin.

However, since the alkali-dispersed hot-melt adhesives of Patent Documents 1 and 2 contain a large amount of petroleum-based tackifier resin, synthetic oil, and the like, they are not preferable in consideration of environmental harmony.

In addition, the demands of consumers regarding the adhesiveness between PET bottles and labels are becoming stricter year by year. The hot melt adhesive for labels is required to have a "holding power" for holding a label in a PET bottle with a certain strength or higher and a "adhesive strength retention rate" for maintaining the adhesive strength for a long period of time. However, it cannot be said that the alkali-dispersed hot-melt adhesives of Patent Documents 1 and 2 sufficiently satisfy these strict demands of consumers.

Furthermore, in recent years, awareness of environmental issues has increased, and awareness of recycling has increased, and it is also required to separate labels and bottles without alkaline cleaning. Therefore, the hot melt adhesive is required not only to have alkali dispersibility and adhesiveness (holding power, adhesive strength retention rate over time), but also to have label removability (for example, manual peeling property) without using an alkaline solution. .. In addition, in this specification, when it simply describes as "removability", it means the removability by hand, for example, without using an alkaline solution.

Japanese Unexamined Patent Publication No. 2005-220244 Japanese Patent No. 4278704

The present invention solves the above-mentioned problems, has high alkali dispersibility, has excellent label holding power, can maintain adhesive strength for a long period of time, and can re-peel the label without using an alkaline solution. It is an object of the present invention to provide a mold hot melt adhesive.

The present invention and preferred embodiments of the present invention are as follows.

1. 1. (A) Thermoplastic block copolymer, which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound,
(B) Adhesive-imparting resin and
(C) Containing at least one selected from the group consisting of fatty acids and derivatives thereof.
An alkali-dispersed hot-melt adhesive in which (A) the thermoplastic block copolymer contains (A1) a styrene-based block copolymer having a styrene content of 40% by weight or more.

2. (B) The alkali-dispersed hot-melt adhesive according to 1 above, wherein the tackifier resin contains a rosin-based tackifier resin having an acid value of 100 mgKOH / g to 300 mgKOH / g.

3. 3. (B) The alkali-dispersed hot-melt adhesive according to 2 above, wherein the tackifier resin further contains an α-methylstyrene resin.

4. (C) The alkali dispersion according to any one of 1 to 3 above, wherein at least one selected from the group consisting of fatty acids and derivatives thereof contains at least one vegetable oil selected from the group consisting of sunflower oil and rice bran oil. Mold hot melt adhesive.

5. The alkali dispersion according to any one of 1 to 4 above, wherein 10 to 30 parts by weight of the component (C) is contained with respect to 100 parts by weight of the total weight of the component (A), the component (B) and the component (C). Mold hot melt adhesive.

6. A label coated with the alkali-dispersed hot-melt adhesive according to any one of 1 to 5 above.

7. A container to which the label described in 6 above is affixed.

The alkali-dispersed hot-melt adhesive of the present invention can be used for adhering a label to a container such as a PET bottle or a glass bottle, has excellent label holding power, and can maintain the adhesive power for a long time. Further, when the container is immersed in an alkaline aqueous solution with the label affixed, the alkali dispersibility is high, and the label can be peeled off again without using the alkaline aqueous solution.

Further, the label attached to a container such as a PET bottle by the hot melt adhesive of the present invention is not only held for a long period of time, but when it is peeled off from the container, it is peeled off without adhesive residue by hand force or the like.

Further, the container to which the label of the present invention is affixed is suitable for recycling because the label can be peeled off cleanly by alkaline washing or hand force.

The alkali-dispersed hot melt pressure-sensitive adhesive according to the present invention includes (A) a thermoplastic block copolymer which is a copolymer of a vinyl-based aromatic hydrocarbon and a conjugated diene compound, (B) a tackifier resin, and (C). It contains at least one selected from the group consisting of fatty acids and derivatives thereof. In addition, in this specification, it may be described as "component (A)", "component (B)" and "component (C)", respectively, and refers to the alkali-dispersed hot melt adhesive of the present invention. , May simply be described as "hot melt adhesive".

The removability of the label, the holding power of the label, and the alkali dispersibility are contradictory properties. By containing the component (A1) and the component (B) described below, the hot melt adhesive of the present invention can improve both of the above-mentioned contradictory properties, and the adhesive strength is stable over time. Become.

<(A) Thermoplastic block copolymer>
In the present invention, the "(A) thermoplastic block copolymer" is a copolymer in which a vinyl-based aromatic hydrocarbon and a conjugated diene compound are block-copolymerized, and is usually a vinyl-based aromatic hydrocarbon block. A resin composition having a conjugated diene compound block.

In the present invention, the (A) thermoplastic block copolymer {component (A)} may be described as (A1) a styrene-based block copolymer having a styrene content of 40% by weight or more (“component (A1)”). There is.) Is included. "Styrene content" refers to the proportion of styrene contained in the thermoplastic block copolymer. The styrene content of the component (A1) is 40% by weight or more, preferably 50% by weight or more, and more preferably 50 to 70% by weight. The hot melt adhesive of the present invention is excellent in both label holding power and label removability when the styrene content of the component (A1) is in the above range.

In the hot melt adhesive of the present invention, the component (A1) is preferably 30 parts by weight or more, more preferably 50 parts by weight or more, and 80 parts by weight, based on 100 parts by weight of the total amount of the component (A). It is more preferably parts or more, and may be 100 parts by weight.

Here, the "vinyl-based aromatic hydrocarbon" means an aromatic hydrocarbon compound having a vinyl group, and specifically, for example, styrene, o-methylstyrene, p-methylstyrene, p-tert-. Examples thereof include butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, and vinylanthracene. Styrene is particularly preferable. These vinyl aromatic hydrocarbons can be used alone or in combination.

The "conjugated diene compound" means a diolefin compound having at least a pair of conjugated double bonds. Specifically, as the "conjugated diene compound", for example, 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene, 1,3- Pentaziene and 1,3-hexadiene can be exemplified. 1,3-butadiene and 2-methyl-1,3-butadiene are particularly preferable. These conjugated diene compounds can be used alone or in combination.

The (A) thermoplastic block copolymer used in the present invention may be a non-hydrogenated additive or a hydrogenated additive.

The “(A) unhydrogenated additive of the thermoplastic block copolymer” can be specifically exemplified by a block based on a conjugated diene compound to which no hydrogenation has been added. Further, the “(A) hydrogenated block copolymer of thermoplastic block” can be specifically exemplified by a block copolymer in which all or part of a block based on a conjugated diene compound is hydrogenated.

The hydrogenated ratio of "(A) hydrogenated product of thermoplastic block copolymer" can be indicated by "hydrogenation rate". The "hydrogenation rate" of "(A) Hydrogenated product of thermoplastic block copolymer" is based on the total aliphatic double bond contained in the block based on the conjugated diene compound, and hydrogenated therein. The ratio of double bonds converted into saturated hydrogen bonds. This "hydrogenation rate" can be measured by an infrared spectrophotometer, a magnetic resonance imaging device, or the like.

Specific examples of the "(A) unhydrogenated additive of the thermoplastic block copolymer" include, for example, a styrene-isoprene block copolymer (also referred to as "SIS") and a styrene-butadiene block copolymer ("SBS"). Also referred to as). Specific examples of the "(A) thermoplastic block copolymer hydrogenated product" include hydrogenated styrene-isoprene block copolymer (also referred to as "SEPS") and hydrogenated styrene-butadiene block. Examples thereof include a copolymer (also referred to as "SEBS") and a styrene-butylene-butadiene-styrene block copolymer (also referred to as "SBBS").

The (A) thermoplastic block copolymer can be used alone or in combination of two or more, and as one embodiment, (A1) a styrene-based block copolymer having a styrene content of 40% by weight or more and (A1). ) May be blended with a styrene block copolymer that does not correspond to). The styrene-based block copolymer that does not correspond to (A1) means that the styrene-based block copolymer has a styrene content of less than 40% by weight (hereinafter, "(A2) a styrene-based block copolymer having a styrene-based content of less than 40% by weight". , Or "ingredient (A2)").

In the present invention, as it is weight average molecular weight of the compound (Mw) of the included components (A), preferably from ^{1.0 × 10 4 ~3.0 × 10 5} , 5.0 × 10 4 ~2.0 × and more preferably 10 ^5.

In the present specification, the weight average molecular weight is determined by converting the molecular weight using a calibration curve using polystyrene having a monodisperse molecular weight as a standard substance using gel permeation chromatography (GPC).

In the present invention, a commercially available product can be used as the (A1) styrene-based block copolymer having a styrene content of 40% by weight or more. For example
Asahi Kasei Chemicals Co., Ltd. Asaplen T439 (trade name), Toughprene 125 (trade name), Toughprene A (trade name), Toughtech P2000 (trade name);
TR2000 (trade name), TR2250 (trade name) manufactured by JSR Corporation;
SOlT6414 (trade name) manufactured by Enichem;
Kraton A1535 (trade name) manufactured by Clayton can be mentioned.

(A2) As a commercially available styrene-based block copolymer having a styrene content of less than 40% by weight,
Asahi Kasei Chemicals Co., Ltd. Tough Plane T125 (trade name), Tough Tech L518X (trade name), Tough Tech H1053 (trade name);
ZEON Corp.'s Quintac3460 (trade name), Quintac3433N (trade name), Quintac3520 (trade name), Quintac3270 (trade name);
Examples thereof include D1160 (trade name), Kraton G1650 (trade name), Kraton G1652 (trade name), and Kraton G1657 (trade name) manufactured by Kraton. These commercially available products can be used alone or in combination.

<(B) Adhesive-imparting resin>
The hot melt adhesive of the present invention can improve the holding power of the label on the container by containing (B) the tackifier resin (component (B)). The "tacking resin" is not particularly limited as long as it is usually used for a hot melt adhesive and can obtain the hot melt adhesive intended by the present invention. In this specification, the component (B) does not include the compound described as the above component (A).

Examples of the tackifying resin include natural rosin, modified rosin, hydrocarbon rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, and pentaerythritol ester of hydrocarbon rosin. , Natural terpene copolymers, 3D polymers of natural terpenes, Hydrocarbon derivatives of hydrogenated terpene copolymers, Polyterpene resins, Hydrocarbon derivatives of phenolic modified terpene resins, aliphatic petroleum hydrocarbon resins, aliphatic petroleum hydrocarbon resins Examples thereof include hydrides, aromatic petroleum hydrocarbon resins, hydrides of aromatic petroleum hydrocarbon resins, cyclic aliphatic petroleum hydrocarbon resins, and hydrides of cyclic aliphatic petroleum hydrocarbon resins.

Of these, the component (B) preferably contains a tackifier resin having an acid value of 0 to 300 mgKOH / g, and more preferably contains a rosin-based tackifier resin having an acid value of 0 to 300 mgKOH / g. It is more preferable to contain a rosin-based tackifier resin having a value of 100 to 300 mgKOH / g, and most preferably to contain a rosin-based tackifier resin having an acid value of 150 to 250 mgKOH / g. When the acid value is within this range, the alkali dispersibility of the hot melt adhesive of the present invention is further improved.

As one aspect of the present invention, it is preferable that the (B) tackifier resin contains an α-methylstyrene resin in addition to the rosin-based tackifier resin. The α-methylstyrene resin has the effect of increasing the cohesiveness of the hot melt adhesive and improving the removability and holding power. As the α-methylstyrene resin, for example, an α-methylstyrene homopolymer or a styrene / α-methylstyrene copolymer is used.

As one embodiment of the present invention, the α-methylstyrene resin as the component (B) is preferably a styrene / α-methylstyrene copolymer, particularly at a softening point of 85 to 160 ° C. (in the ring-ball method specified in JIS K2207). Measurement) is more preferable. Specifically, Eastman Chemical Company's Crystallex 3085 (trade name), Crystallex 3100 (trade name), Crystallex 1120 (trade name), Crystallex 5140 (trade name), Endix 155, Plastrin 290, Mitsui Chemicals, Inc. Examples of commercially available products such as FTR-2120 (trade name) manufactured by FTR-2120 can be exemplified.

These tackifier resins can be used alone or in combination of two or more. As the tackifier resin, a liquid type tackifier resin can also be used as long as the color tone is colorless to pale yellow, there is substantially no odor, and the thermal stability is good.

<(C) Fatty acid and its derivatives>
The hot melt adhesive of the present invention contains at least one (component (C)) selected from the group consisting of (C) fatty acids and derivatives thereof. When the hot melt adhesive contains the component (C), the hot melt adhesive of the present invention has excellent alkali dispersibility.

In the present specification, the fatty acid refers to an aliphatic carboxylic acid having at least one carboxy group, and may have a hydroxy group. Fatty acids are roughly classified into saturated fatty acids and unsaturated fatty acids. Saturated fatty acids are acids that do not have double or triple bonds in their carbon chains. Unsaturated fatty acids are acids that have double or triple bonds in their carbon chains.

The saturated fatty acid may be any saturated fatty acid as long as it does not adversely affect the hot melt adhesive of the present invention, preferably one having 1 to 30 carbon atoms, more preferably 3 to 26 carbon atoms, and 8 to 24 carbon atoms. The one having 12 to 22 carbon atoms is more preferable. Further, the saturated fatty acid may be chain-like or cyclic, and is preferably chain-like. The chain-shaped saturated fatty acid may be linear or has a branched chain, and a linear saturated fatty acid is preferable. Specific examples of the saturated fatty acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, tricosylic acid, and 12-hydroxystearic acid. Illustrated.

The unsaturated fatty acid may be any fatty acid that does not adversely affect the hot melt adhesive of the present invention, preferably one having 3 to 26 carbon atoms, more preferably 4 to 22 carbon atoms, and 14 to 14 carbon atoms. 22 is more preferred.

The number of carbon-carbon unsaturated bonds of the unsaturated fatty acid is preferably 1 to 6, more preferably 1 to 3, and most preferably 1 to 2.

Examples of unsaturated fatty acids include crotonic acid, oleic acid, linolenic acid, docosahexaenoic acid, linoleic acid, ricinoleic acid and the like.

In the present specification, the fatty acid derivative is a compound obtained by substitution of the above fatty acid or other chemical reaction. Examples of the fatty acid derivative include fats and oils, hydrogenated oils, fatty acid amides, fatty acid alkyl esters, monoglycerides, diglycerides, sorbitan fatty acid esters, diglycerin fatty acid esters and the like, and fats and oils and hydrogenated oils are preferable. "Fat and oil" contains triglyceride (triacylglycerol), which is an ester of fatty acid and glycerin, as a main component.

The hot melt adhesive of the present invention can contain fats and oils generally used as edible or industrial fats and oils. The fats and oils may be liquid or solid at room temperature (about 20 to 26 ° C.), preferably liquid at room temperature, and preferably vegetable oil. Examples of fats and oils include corn oil, soybean oil, epoxidized soybean oil, sesame oil, flaxseed oil, olive oil, lettuce oil, fish oil, butter, lard, sunflower oil, rapeseed oil, sunflower oil, rice oil, and cottonseed oil. One type may be used alone, or two or more types may be used in combination. Of these, at least one selected from sunflower oil and rice oil is particularly preferable. By including sunflower oil and / or rice bran oil, the alkali-dispersed hot-melt adhesive of the present invention has particularly excellent alkali dispersibility.

"Hydrogenated oil" is a solidified oil or fat at room temperature by hydrogenating the oil or fat that is liquid at room temperature to increase the proportion of saturated fatty acids having a higher melting point. The "hydrogenated oil" may be any one that does not adversely affect the hot melt adhesive of the present invention, and specifically, hydrogenated castor oil (that is, hydrogenated castor oil), hydrogenated soybean oil, and the like. Examples include hydrogenated salad oil.

As the fatty acid (C) or a derivative thereof, a commercially available product can be used. As such a commercial product, for example,
Showa Sangyo Co., Ltd. FS oil (trade name), prime taste (trade name);
Rice oil (trade name), rice bran salad oil (trade name) manufactured by Bosoh Oil & Fat Co., Ltd .;
Cottonseed oil manufactured by Okamura Oil & Fat Co., Ltd. (trade name);
Riken Vitamin Co., Ltd. Rikemar (trade name);
Nonion (trade name) manufactured by NOF CORPORATION;
And so on. These commercially available fatty acid derivatives can be used alone or in combination.

The hot melt adhesive of the present invention may contain wax in addition to the components (A) to (C).

The "wax" is a wax generally used for a hot melt adhesive, and is not particularly limited as long as the hot melt adhesive intended by the present invention can be obtained. Specific examples thereof include synthetic waxes such as Fishertropus wax and polyolefin wax (polyethylene wax and polypropylene wax); petroleum waxes such as paraffin wax and microcrystalline wax; and natural waxes such as castor wax.

Since the hot melt adhesive of the present invention contains wax, when the label is peeled off from the container, the adhesive residue on the container of the hot melt adhesive is reduced.

The hot melt adhesive of the present invention may contain a plasticizer.

The plasticizer is blended for the purpose of reducing the melt viscosity of the hot melt adhesive, imparting flexibility, and improving the wetting of the adherend, and is compatible with other components to obtain the hot melt adhesive of the present invention. As long as it can be obtained, it is not particularly limited. Examples of the plasticizer include paraffin-based oils, naphthenic oils, and aromatic oils. In particular, paraffin-based oil and / or naphthenic oil is preferable, and colorless and odorless paraffin-based oil is most preferable.

As an example of a commercially available plasticizing agent, for example, White Oil Bloom350 (trade name) manufactured by Kukdong Oil & Chem, Diana Fresia S-32 (trade name) manufactured by Idemitsu Kosan Co., Ltd., Diana Process Oil PW-90 (trade name), Daphne Oil KP-68 (trade name), EmperM1930 (trade name) manufactured by BP Chemicals, Kaydol (trade name) manufactured by Crompton, Primol352 (trade name) manufactured by Exxon, Process Oil NS manufactured by Idemitsu Kosan Co., Ltd. -100 (trade name) can be exemplified. These can be used alone or in combination of two or more.

By blending the plasticizer, the compatibility of the components (A) to (C) contained in the hot melt adhesive of the present invention is improved, and further, the compatibility with other components is also improved, and as a result, the compatibility is improved. Improves the adhesiveness, adhesiveness and coating suitability of hot melt adhesives.

The hot melt adhesive according to the present invention may further contain various additives, if necessary. Examples of such various additives include stabilizers and fine particle fillers.

The "stabilizer" is blended to improve the stability of the hot melt adhesive by preventing the decrease in molecular weight, gelation, coloring, generation of odor, etc. due to the heat of the hot melt adhesive. As long as the hot melt adhesive intended by the present invention can be obtained, the present invention is not particularly limited. Examples of the "stabilizer" include antioxidants and ultraviolet absorbers.

Examples of the "antioxidant" include phenolic antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Examples of the "ultraviolet absorber" include benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers. Further, a lactone-based stabilizer can be added. These can be used alone or in combination. The following products can be used as commercial products of antioxidants.

Specifically, Sumitomo Chemical Industry Co., Ltd.'s Sumilyzer GM (trade name), Sumilyzer TPD (trade name) and Sumilyzer TPS (trade name), Ciba Specialty Chemicals' Irganox 1010 (trade name), Irga Knox HP2225FF (trade name), Irgafos 168 (trade name) and Irganox 1520 (trade name), Chinubin P, JF77 (trade name) manufactured by Johoku Chemical Co., Ltd., Tominox TT (trade name) manufactured by AP Corporation, Adeca AO-412S (trade name) manufactured by the company can be exemplified. These stabilizers can be used alone or in combination.

"UV absorbers" are used to improve the light resistance of hot melt adhesives. "Antioxidants" are used to prevent oxidative deterioration of hot melt adhesives.

The hot melt adhesive of the present invention may further contain a fine particle filler. The fine particle filler may be any generally used one, and is not particularly limited as long as the hot melt adhesive intended by the present invention can be obtained. Examples of the "fine particle filler" include mica, calcium carbonate, kaolin, talc, titanium oxide, diatomaceous earth, urea resin, styrene beads, calcined clay, starch and the like. These shapes are preferably spherical, and their dimensions (diameter in the case of spherical shape) are not particularly limited.

The hot melt adhesive according to the present invention uses a generally known method for producing a hot melt adhesive, and contains components (A), component (B) and component (C), preferably wax and a plasticizer. It can be produced by blending a stabilizer, a stabilizer, and various additives as needed. The hot melt adhesive can be produced by blending a predetermined amount of the above-mentioned components and heating and melting. As long as the desired hot melt adhesive can be obtained, the order in which each component is added, the heating method, and the like are not particularly limited.

In the hot melt adhesive of the present invention, the blending amount of the component (A) is 10 to 40 parts by weight with respect to 100 parts by weight of the total weight of the component (A), the component (B) and the component (C). It is preferable, and more preferably 15 to 30 parts by weight. When the blending amount of the component A is within the above range, the alkali-dispersed hot-melt adhesive of the present invention has an excellent balance between removability and holding power.

In the hot melt adhesive of the present invention, the blending amount of the component (B) is 30 to 80 parts by weight with respect to 100 parts by weight of the total weight of the component (A), the component (B) and the component (C). It is preferably 40 to 70 parts by weight, more preferably 40 to 70 parts by weight. When the blending amount of the component (B) is within the above range, the alkali-dispersed hot-melt adhesive of the present invention becomes stable as a hot-melt adhesive, and the adhesive strength can be maintained for a long period of time. ..

In the hot melt adhesive of the present invention, the blending amount of the component (C) is preferably 10 to 30 parts by weight with respect to 100 parts by weight of the total weight of the component (A), the component (B) and the component (C). In particular, it is more preferably 15 to 25 parts by weight. When the blending amount of the component (C) is within the above range, the alkali-dispersable hot-melt adhesive of the present invention is further improved in alkali-dispersible property.

As a further preferred embodiment of the present invention, the hot melt adhesive has a viscosity (or melt viscosity) at 160 ° C. of preferably 4000 mPa · s or less, more preferably 3000 mPa · s or less, and 2000 mPa · s or less. Is particularly preferable. The hot melt adhesive has a viscosity at 160 ° C. in the above range, which makes it more suitable for coating. The viscosity (or melt viscosity) at 160 ° C. as used herein means a value measured with a Brookfield viscometer using a No. 27 rotor.

The label according to the present invention is coated with the hot melt adhesive. Specific examples of labels to which the hot melt adhesive is applied include paper, processed paper (paper that has been subjected to aluminum vapor deposition processing, aluminum laminating processing, varnish processing, resin processing, etc.), synthetic paper and other papers, and organic materials. Examples thereof include labels made of compound films, inorganic compound films, metal films and the like.

As the label used in the present invention, a film of an organic compound such as polypropylene, polyethylene terephthalate (PET), or polylactic acid (PLA), which is often used for alkaline cleaning, is particularly preferable. As the polypropylene film, a biaxially stretched polypropylene (OPP) film is particularly preferable.

The hot melt adhesive of the present invention may be applied to the entire back surface of the label or a part of the back surface of the label. Examples of the coating method include an open wheel method, a closed gun method, and a direct coating method. The open wheel method and the direct coat method are preferable as a method in which glue does not remain on the PET bottle when the label is peeled off.

The container according to the present invention has the above label affixed to it. Specifically, glass containers such as glass bottles used for soft drinks, seasonings, detergents, shampoos, cooking oils, cosmetics, pharmaceuticals, etc .; plastic containers such as PET (polyethylene terephthalate) bottles; metal cans such as aluminum ; Is exemplified. Among the above-mentioned containers, PET bottles are particularly preferable in the present invention. Examples of a PET bottle having the label of the present invention attached include a PET bottle having a label attached to a part of the body circumference of the PET bottle, and a PET bottle wound around the body of the bottle so as to cover the circumference of the bottle. An embodiment of the present invention includes a "body-wrapping label".

The hot melt adhesive of the present invention is also preferably used for adhering a body-wrapping label. Biaxially stretched polypropylene (OPP) film is often used as the body-wrapping label.

The label to which the hot melt adhesive of the present invention is applied may or may not be printed. When a printed label is used, the hot melt adhesive of the present invention may be applied not only to the non-printed surface but also to the printed surface.

An open wheel type device can be mentioned as a kind of device for attaching a label to a PET bottle using the hot melt adhesive of the present invention. The hot melt adhesive is melted at 120-150 ° C. and applied to the back surface of the label by an open wheel type device. This label is affixed to a PET bottle to manufacture the container of the present invention.

The container to which the label is attached by the hot melt adhesive of the present invention is suitable for reuse of the container because the label is easily peeled off from the container when it is immersed in a hot alkaline solution. The method of peeling the label with a thermo-alkali solution is not particularly limited, but for example, the container to which the label is attached is cut into small pieces into pellets, and the thermo-alkali aqueous solution (for example, temperature 80 ° C. to 90 ° C., concentration 0) is used. A method of putting this pellet in (5 to 5 wt% aqueous sodium hydroxide solution) and stirring for about 1 minute to 2 hours can be mentioned.

Further, the container to which the label is attached by the hot melt adhesive of the present invention has sufficient adhesiveness without the label peeling off from the container when using a normal container, but when the label is peeled off after using the container or the like. Can be peeled off by hand without adhesive residue, and has excellent re-peelability.

Hereinafter, the present invention will be described with reference to examples for the purpose of explaining the present invention in more detail and concretely, but these examples do not limit the present invention in any way.

Examples and Comparative Examples and your reference example illustrates the components to be blended into a hot melt adhesive in the following. In the following, "Example 2" shall be read as "Reference Example 2".

(A) Thermoplastic Block Copolymer (A1) Styrene-based Block Copolymer (A1-1) SBS with a styrene content of 40% by weight or more ("TR2250" manufactured by JSR Corporation)
(A1-2) SBS ("TR2000" manufactured by JSR Corporation)
(A1-3) SBBS ("Clayton A-1535" manufactured by Clayton)
(A1-4) SBBS ("Tough Tech P2000" manufactured by Asahi Kasei Chemicals Co., Ltd.)

(A2) Styrene-based block copolymer (A2-1) SEBS having a styrene content of less than 40% by weight (“Clayton G-1650” manufactured by Clayton)
(A2-2) SEBS ("Clayton G-1652" manufactured by Clayton)
(A2-3) SEBS ("Clayton G-1657" manufactured by Clayton)

(B) Adhesive-imparting resin (B1) Rosin-based resin (Haritac F (trade name) manufactured by Harima Chemicals, acid value 165 to 175 mgKOH / g)
(B2) Rosin-based resin (ForalAX-E (trade name) manufactured by Eastman Chemical Company, acid value 166 mgKOH / g)
(B3) Rosin resin (KE-604 (trade name) manufactured by Arakawa Chemical Co., Ltd., acid value 230 to 245 mgKOH / g)
(B4) C9 petroleum resin (Arcon M100 (trade name) manufactured by Arakawa Chemical Co., Ltd., acid value 0 mgKOH / g)
(B5) C9 petroleum resin (Arcon M115 (trade name) manufactured by Arakawa Chemical Co., Ltd., acid value 0 mgKOH / g)
(B6) α-Methylstyrene resin (Crystalex 3100 (trade name) manufactured by Eastman Chemical Company, acid value 0 mgKOH / g)
(B7) Terpene resin (Clearon M105 (trade name) manufactured by Yasuhara Chemical Co., Ltd., acid value 0 mgKOH / g)
(B8) α-Methylstyrene resin (Endix 155 (trade name) manufactured by Eastman Chemical Company, acid value 0 mgKOH / g)
(B9) α-Methylstyrene resin (Plastrin 290 (trade name) manufactured by Eastman Chemical Company, acid value 0 mgKOH / g)

(C) At least one selected from the group consisting of fatty acids and their derivatives (C1) Rapeseed oil (FS oil (trade name) manufactured by Showa Sangyo Co., Ltd.)
(C2) Sunflower oil (Showa Sangyo Prime Taste (trade name))
(C3) Rice oil (rice bran oil made from Bosoh oil (trade name))
(C4) Cottonseed oil (cottonseed oil manufactured by Okamura Oil (trade name))
(C5) Oleic acid (PM500 made by Miyoshi Oil & Fat (trade name))
(C6) Sorbitan fatty acid ester (Kao's Leodor TW-0320V (trade name))
(C7) Sorbitan fatty acid ester (NOF Nonion 80R (trade name))
(C8) Diglycerin fatty acid ester (Rikemar L-71-D (trade name) made by RIKEN Vitamin)

(C'9) Mineral oil (Diana Fresia S-32 (trade name) manufactured by Idemitsu Kosan)

(D) Wax (D1) Maleic anhydride-modified polypropylene wax (Licosen PPMA6202 (trade name) manufactured by Clariant AG)
(D2) Acid-modified wax (Hiwax1105A (trade name) manufactured by Mitsui Chemicals, Inc.)

(E) Antioxidant (E1) Sulfur-based antioxidant (AO-412S (trade name) manufactured by ADEKA CORPORATION)
(E2) Phenolic antioxidant (Sumilyzer GM (trade name) manufactured by Sumitomo Chemical Co., Ltd.)

The components (A) to (E) are blended in the blending ratios shown in Tables 1 to 3, melt-mixed at about 145 ° C. for about 3 hours using a universal stirrer, and Examples 1 to 11 and Comparative Examples 1 to 1 6 hot melt adhesives were produced. All numerical values relating to the composition (blending) of the hot melt adhesive shown in Tables 1 to 3 are parts by weight.

Alkali dispersibility, removability, holding power, and adhesive strength retention rate were evaluated for each of the hot melt adhesives of Examples and Comparative Examples. Hereinafter, each measurement method and evaluation method will be described.

<Alkaline dispersibility>
A label (25 mm × 50 mm) of an OPP film was prepared with the hot melt adhesive of each Example and each Comparative Example, and the label was attached to a PET bottle to prepare a test sample. After measuring the weight of the test sample (the weight of the test sample before washing), the test sample was placed in a 1.5 wt% sodium hydroxide aqueous solution at 85 ° C. and stirred (washed) for 15 minutes. After 15 minutes, the test sample was taken out and air-dried sufficiently. The weight of the test sample after air drying (the weight of the test sample after washing) was measured, and the alkali dispersion rate was calculated from the weight before and after washing. The alkali dispersibility was evaluated by calculating the alkali dispersion rate from the following formula.

Alkali dispersion rate (%) = {(weight before cleaning of test sample-weight after cleaning of test sample) / (weight of hot melt adhesive used)} x 100

The results are shown in Tables 1 to 3. The evaluation criteria are as follows.
◎: Alkali dispersion rate is higher than 80% ○: Alkali dispersion rate is 60% or more, 80% or less ×: Alkali dispersion rate is less than 60% Measurement impossible: Measurement is not possible because the film does not adhere and a test sample cannot be prepared.

<Removability: OPP film / OPP film>
The hot-melt adhesives of each example and each comparative example were applied to an OPP film having a thickness of 30 μm to form a 25 μm-thick adhesive layer on the film. Next, this was molded into a width of 10 mm × 50 mm to prepare a test body.

The test piece was attached to another OPP film as an adherend in an atmosphere of 20 ° C. The bonding conditions were heat bonding at 100 ° C. for 1 second. After laminating both films, they were cured at room temperature for 2 hours. Then, the peeling was performed under the condition of a peeling speed of 300 mm / min using a universal tensile tester (RTM250 manufactured by Orientec Co., Ltd.) in an atmosphere of 20 ° C. Three samples were measured for each hot melt adhesive and evaluated by visually observing their fracture states. The evaluation criteria are as follows. In the present specification, "interface fracture" means that when the test piece is peeled from the adherend, the test piece is peeled off at the interface between the test piece and the adherend, and no adhesive layer remains on the adherend. means. "Coagulation failure" means a state in which the pressure-sensitive adhesive layer is broken when the test piece is peeled from the adherend. The results are shown in Tables 1 to 3.
○: Interfacial fracture ×: Aggregate fracture cannot be measured: Measurement is not possible because the film does not adhere and a test sample cannot be prepared.

<Removability: OPP film / PET film>
The same measurement as the removability test of the OPP film / OPP film was performed except that the film to be adhered was a PET film, and the fracture state of the OPP film / PET film was evaluated. The results are shown in Tables 1 to 3. The evaluation criteria are as follows.
○: Interfacial fracture ×: Aggregate fracture cannot be measured: Measurement is not possible because the film does not adhere and a test sample cannot be prepared.

<Removability: OPP film / glass>
The same measurement as the removability test of the OPP film / OPP film was performed except that the OPP film to be the adherend was made of glass, and the fracture state of the OPP film / glass was evaluated. The results are shown in Tables 1 to 3. The evaluation criteria are as follows.
○: Interfacial fracture ×: Aggregate fracture cannot be measured: Measurement is not possible because the film does not adhere and a test sample cannot be prepared.

<Holding power>
The hot melt adhesives of each example and each comparative example were applied to an OPP film having a thickness of 30 μm to form an adhesive layer having a thickness of 25 μm on the film. Next, this was molded into a size of 25 mm × 50 mm to obtain a test body. An OPP film was bonded to this test piece by heat bonding at 100 ° C. for 5 seconds so that the bonding area was 25 mm × 25 mm to prepare a test sample, and then a weight of 500 g was placed perpendicularly to the bonded surface and below. It was left under the condition of 40 ° C. The evaluation criteria are as follows. The results are shown in Tables 1 to 3.
○: Time that can hold the weight (holding power) is 100 minutes or more ×: Time that can hold the weight (holding power) is less than 100 minutes Measurement is not possible: Measurement is not possible because the film does not adhere and a test sample cannot be created.

<Adhesive stability over time (adhesive strength maintenance rate)>
The hot-melt adhesives of each example and each comparative example were applied to an OPP film having a thickness of 30 μm to form a pressure-sensitive adhesive layer having a thickness of 25 μm on the film. Next, this was molded into a width of 10 mm × 50 mm to prepare a test body.

The test piece was attached to another OPP film in an atmosphere of 20 ° C. The bonding condition was heat bonding at 100 ° C. for 1 second. Both films were bonded together to form a test sample, which was then stored at 50 ° C. for 8 hours and then at 5 ° C. for 16 hours. After repeating the storage cycle four times, both films were peeled off at a peeling speed of 300 mm / min using a universal tensile tester (RTM250 manufactured by Orientec Co., Ltd.) in an atmosphere of 20 ° C., and the adhesive strength was measured.

The adhesive strength immediately after bonding and the adhesive strength after storage were measured, and the adhesive strength maintenance rate was calculated. Three samples were measured for each hot melt adhesive, and their adhesive strength retention rate was evaluated by calculating by the following formula.

Adhesive strength maintenance rate (%) = (Adhesive strength after storage / Adhesive strength immediately after bonding) x 100

The results are shown in Tables 1 to 3. The evaluation criteria are as follows.

◯: Higher than 80% Δ: 50% or more, 80% or less ×: Less than 50% Measurement not possible: Measurement is not possible because the film does not adhere and a test sample cannot be prepared.

As shown in Tables 1 and 2, the hot melt adhesives of Examples 1 to 11 contain all of the components (A1), (B) and (C), and thus are alkaline dispersibility and relabeled. The peelability, holding power, and adhesive strength retention rate are all good. On the other hand, as shown in Table 3, since the hot melt adhesive of the comparative example does not contain any of the components (A1), (B) and (C), whether any of the above performances is x. Alternatively, the film cannot be adhered, and it cannot be said that it is suitable as an alkali-dispersed hot-melt adhesive.

The present invention can provide an alkali-dispersed hot-melt adhesive, a label coated with the hot-melt adhesive, and a container to which the label is attached.

Claims (4)

(A) Thermoplastic block copolymer, which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound,
(B) Adhesive-imparting resin and
(C) Containing at least one selected from the group consisting of fatty acids and derivatives thereof.
The (A) thermoplastic block copolymer contains (A1) a styrene-based block copolymer having a styrene content of 40% by weight or more .
(C) An alkali-dispersed hot-melt adhesive containing at least one selected from sunflower oil and rice oil as a fatty acid and a derivative thereof . The alkali-dispersed hot according to claim 1, wherein the blending amount of the component (C) is 10 to 30 parts by weight with respect to 100 parts by weight of the total weight of the component (A), the component (B) and the component (C). Melt adhesive . A label coated with the alkaline dispersion type hot melt adhesive according to claim 1 or 2. A container to which the label according to claim 3 is affixed.