JP6756122B2 - Hot melt adhesive and sheet with hot melt adhesive - Google Patents

Description

The present invention relates to a hot melt adhesive, a sheet with a hot melt adhesive made by using the hot melt adhesive, and a container to which the sheet with the hot melt adhesive is attached.

The outer circumference of the body of a polyethylene terephthalate (hereinafter referred to as PET) bottle has a product label for displaying the product name, etc., and a POP label for catch copy or product advertisement. Melt adhesive is used.

Hot-melt adhesives are used in the method of applying and pasting on a base material in a heat-melted state and then cooling and solidifying, and the product labeling labels are "body-wrapping label method", "shrink label method", etc. It is mainly used when pasting with.
In addition, the one used in the method of attaching by applying to the base material in a heated and melted state, cooling and solidifying, and then attaching with a tack is called a hot melt adhesive, and is mainly used when attaching a POP label. Has been done. The pressure-sensitive adhesive can also be used as an adhesive.

These PET bottles are required to be collected and recycled as raw materials.
For example, the'Guidelines for Self-Regulation of Designated PET Bottles' issued by the PET Bottle Recycling Promotion Council show the following indicators. That is, when pellets made by cutting labeled bottles are immersed in a 1.5% NaOH aqueous solution at 90 ° C. at a pellet concentration of 10% (weight ratio) and stirred for 15 minutes, the labels are labeled from the PET pellets. Is an index that the printing ink, adhesive, etc. do not remain on the PET pellets.
Therefore, alkali dispersibility is an essential item for hot melt adhesives used in recycled containers such as PET bottles.

Patent Document 1 discloses a water-dispersible pressure-sensitive adhesive composition containing copolyester, which is a hot-melt pressure-sensitive adhesive composition. However, the copolyester described in Patent Document 1 has a problem that the adhesive strength of the pressure-sensitive adhesive composition is not stable because it is partially thermally decomposed due to its poor heat resistance. There is also a problem such as having an odor.
Patent Document 2 describes a hot melt containing a thermoplastic elastomer, a rosin-based tackifier having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less, a terpenphenol resin, synthetic oil, and polypropylene wax graft-polymerized with maleic anhydride. Adhesives are disclosed.
Patent Document 3 describes a thermoplastic elastomer, a rosin-based tackifier having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less, a synthetic oil, a wax having a needle penetration of 10 dmm or less at 25 ° C., and a number average molecular weight of 1000. The hot melt adhesive containing the above polyethylene glycol is disclosed.
Patent Document 4 discloses a thermoplastic elastomer, a solid tackifier having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less, a liquid tackifier, a wax, and a hot melt adhesive containing a specific nonionic surfactant. Has been done.

Special Table No. 11-512134 Japanese Unexamined Patent Publication No. 2010-90185 JP-A-2010-280878 Japanese Unexamined Patent Publication No. 2012-1624

By the way, various base materials are also used for product display labels and POP labels.
The base material of the product label is polypropylene or PET, and a film having a base material thickness of 15 to 30 μm is used. On the other hand, the material of the POP label includes paper, YUPO, an aluminum vapor-deposited film, and the like in addition to the base material used for the product display label, and the thickness of the base material is widely selected from 15 μm to 120 μm. The alkali dispersibility of the hot melt adhesive is affected by the base material, and the higher the density and thickness of the base material, the more difficult it is for the NaOH aqueous solution to permeate, resulting in poor alkali dispersibility. In particular, plastic films are required to have high alkali dispersibility.
In addition, the POP label must be a hot melt adhesive that can develop tack and be attached for several months after application, unlike the hot melt adhesive that is attached immediately after hot melt application like the product label. ..

The product label using the hot melt adhesive disclosed in References 2 to 4 can be peeled off from the PET bottle with a hot alkaline aqueous solution, but the POP label using a plastic film does not have sufficient alkali dispersibility. There was a problem that it could not be removed from the PET bottle.
The hot melt disclosed in References 2 to 4 expresses tack and can be used as a hot melt adhesive, but when left to stand in the summer (30 to 40 ° C.) for about one week, the surface becomes white and tack becomes. There was a problem that it could not be used as a hot melt adhesive due to the phenomenon of disappearing.

An object of the present invention is to provide a hot melt adhesive which is excellent in adhesive strength and alkali dispersibility and can be tacked for several months without whitening.

The present invention contains the following (A) to (D) in a total of 90 to 100% by mass in 100% by mass of the hot melt adhesive.
In the total of 100% by mass of the following (A) to (D),
Styrene-based elastomer (A): 10 to 45% by mass,
Rosin ester tackifier (B) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less: 20 to 60% by mass,
Process oil (C) having a pour point of −10 ° C. or lower: 10 to 40% by mass, and an olefin copolymer (D) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less: 1 to 20% by mass.
With respect to hot melt adhesives, including.

The present invention also relates to a hot melt adhesive in which the olefin copolymer (D) is a copolymer of an olefin having 2 to 4 carbon atoms and (meth) acrylic acid.

The present invention also relates to a plastic sheet with a hot melt adhesive, wherein the hot melt adhesive is provided on both opposite ends of the same surface of the quadrilateral plastic sheet.

The present invention also relates to a container with a plastic sheet having the plastic sheet with the hot melt adhesive on the outer periphery of the container.

INDUSTRIAL APPLICABILITY According to the present invention, it has been possible to provide a hot melt adhesive having excellent adhesive strength and alkali dispersibility and which can be tacked for several months without whitening.

First, the hot melt adhesive of the present invention will be described.
Styrene-based elastomer (A), rosin ester tackifier (B) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less, process oil (C) having a pour point of -10 ° C or less, and an acid value of 100 mgKOH / It contains an olefin copolymer (D) having an amount of g or more and 300 mgKOH / g or less.

<Styrene-based elastomer (A)>
Since the styrene-based elastomer (A) has both a rubber component (soft segment: soft phase) having elasticity in the molecule and a molecular restraint component (hard segment: hard phase) for preventing plastic deformation, It has properties intermediate between rubber and plastic. Therefore, the styrene-based elastomer (A) has properties similar to those of vulcanized rubber at room temperature, has elasticity, and can use an existing molding machine as it is at high temperature, like ordinary styrene-based resin.
The styrene-based elastomer (A) has a polystyrene block (S) and a rubber block located between the polystyrene blocks, and the polystyrene block forms a physical crosslink (domain) to serve as a cross-linking point. Gives the product rubber elasticity. Rubber blocks that are soft segments include polybutadiene (B), polyisoprene (I) and polyolefin elastomers (polyethylene (E), polypropylene (P)), unsaturated with double bonds, and hydrogen double bonds. There is added saturation. Further, there are homopolymers consisting of one component and copolymers consisting of two or more components.
By arranging polystyrene blocks and rubber blocks alternately, it has various properties such as viscoelasticity, elasticity, and cohesiveness, and is suitably used as a hot melt adhesive and a hot melt adhesive.

In the present invention, the number of polystyrene blocks and rubber blocks is not limited, but a triblock structure such as polystyrene block-rubber block-polystyrene block and a diblock structure such as polystyrene block-rubber block are preferably used. A triblock structure is preferable. Further, as the rubber block, a saturated copolymer having two or more components composed of polyethylene, polypropylene, polybutadiene, and polyisoprene is preferably used, and more preferably a saturated copolymer of polyethylene and polybutadiene.

The styrene-based elastomer (A) preferably has a melt viscosity of 100 to 50,000 mPa · s (25% toluene solution (25 ° C.)).

<Rosin ester tackifier (B)>
The rosin ester tackifier (B) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less is not particularly limited as long as it is an esterified rosin having a carboxyl group. Rosin is an amber, amorphous natural resin obtained from pine, and can be divided into gum rosin, wood rosin, and tall oil rosin depending on the manufacturing. Its main component is a mixture of abietic acid having three ring structures, a conjugated double bond and a carboxyl group and an isomer thereof, and has a highly reactive bulky structure. Due to its high reactivity, it has poor thermal stability, and rosin is generally hydrogenated or acid-denatured to improve stability. The rosin ester is obtained by a dehydration reaction of a carboxyl group and a hydroxyl group of abietic acid, and the hydroxyl group is not particularly limited, but one having 1 to 9 carbon atoms is preferable. For example, methanol, ethanol, propanol, phenol and the like can be mentioned.

When the acid value is 100 mgKOH / g or more, the alkali dispersibility is excellent, and the plastic label and POP can be easily peeled off from the bottle with a hot alkaline aqueous solution. On the other hand, when the acid value is 300 mgKOH / g or less, the softening point and the viscosity of the hot melt adhesive can be lowered. More preferably, the acid value is 110 to 250 mgKOH / g. More preferably, it is 150 mgKOH / g or more and 200 mgKOH / g or less.

In the present specification, the acid value is the number of mg of potassium hydroxide (KOH) required to neutralize 1 g of the sample. This is measured, for example, by the following method. First, weigh the sample precisely, put it in a 250 ml flask, add 50 ml of an equal volume mixture of ethanol or ethanol and ether, heat to dissolve, and titrate with 0.1 N potassium hydroxide solution with frequent shaking (indicator: phenol). Phenolphthalein). The end point of the titration is the point where the pink color of the liquid remains for 30 seconds. Then, a blank test is performed in the same manner for correction, and the acid value value is obtained from the following formula.
Acid value = [Consumption of 0.1N potassium hydroxide solution (ml) x 5.611] / [Sample amount (g)]

<Process oil (C)>
The process oil (C) used in the present invention has a pour point of −10 ° C. or lower.
The process oil is not particularly limited as long as it is generally used as a plasticizer such as rubber or a thermoplastic elastomer, but it is produced in so-called petroleum refining or the like. The process oil is a mixture of aromatic components, naphthene components, and paraffin-based components. Generally, an aromatic process oil having a total carbon of 30% or more and a naphthene ring carbon of 35 to 45% is used. Those with naphthenic process oils and those with paraffin chain carbon of 50% or more are classified as paraffinic process oils.
Paraffin-based crude oil is separated into paraffin-based oil, aromatic oil, etc. by performing distillation, hydrogenation reforming, solvent extraction, solvent dewaxing, etc. Naphthenic crude oil is also separated into naphthenic oil, aromatic oil, etc. by distillation and solvent extraction.

In the present invention, paraffin-based process oil and naphthenic process oil are preferable as the process oil (C). This is because there is little generation of odor and brown hue, and it is excellent in hygiene and cosmetics. By using paraffin-based process oil and naphthenic process oil having a pour point of −10 ° C. or lower, tack develops even in a low temperature environment of about 5 ° C., and the oil can be mounted in the same manner as at room temperature.

As commercial products of such process oil (C), paraffin-based process oil has a trade name such as "Diana process oil PW series, PS series" from Idemitsu Kosan Co., Ltd., and "Kixx series" from Chusei Oil Co., Ltd. , Nippon Sun Oil Co., Ltd. has various grades on the market under trade names such as "Sun Pure Series". Various grades of naphthenic process oils are commercially available under trade names such as "Diana Fresia Oil N Series" manufactured by Idemitsu Kosan Co., Ltd. and "SNH Series" manufactured by Sankyo Yuka Kogyo Co., Ltd.

In the present specification, the pour point is defined by JIS K2269. Specifically, a test tube containing a 45 mL sample is heated to 45 ° C. in an oven or the like, and then a cooling bath (ice water or sodium chloride) is used. Or put it in ice water mixed with calcium chloride or dry ice) and cool it. Remove the sample from the cooling bath every time the temperature of the sample drops by 2.5 ° C, read the temperature when the sample does not move at all for 5 seconds, and add 2.5 ° C to this value to obtain the pour point.

<Olefin-based copolymer (D)>
The olefin-based copolymer (D) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less used in the present invention is not particularly limited, but is, for example, the common weight of olefin and (meth) acrylic acid. Coalescence is mentioned.
Examples of olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-hexene, 1-octene, 1-nonene, 1-decene, cis-2-butene, trans-2-butene, isobutylene, Examples thereof include cis-2-pentene, trans-2-pentene, 3-methyl-1-butene, 2-methyl-2-butene and 2,3-dimethyl-2-butene, hexene, heptene, octene and deten. Preferably, it is an olefin having 2 to 4 carbon atoms.
Preferably, it is a copolymer of an olefin having 2 to 4 carbon atoms and (meth) acrylic acid.

As a commercially available product of the olefin copolymer (D) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less, a trade name such as "AC5120, AC5180" is given by Honeywell Japan Co., Ltd. It is commercially available at.
More preferably, the acid value is 110-200 mgKOH / g.

The melting point of the olefin-based copolymer (D) is not particularly limited as long as it is made uniform by heating and melting, but it is preferably 0 ° C. to 150 ° C., more preferably 30 ° C. to 140 ° C.

The hot melt pressure-sensitive adhesive of the present invention has a styrene-based elastomer (A): 10 to 45% by mass, an acid value of 100 mgKOH / g or more, and 300 mgKOH / g or less in a total of 100% by mass of (A) to (D). The rosin ester tackifier (B): 20 to 60% by mass, the process oil (C) having a flow point of −10 ° C. or lower: 10 to 40% by mass, and the acid value of 100 mgKOH / g or more and 300 mgKOH / g or less. Olefin-based elastomer (D): Contains 1 to 20% by mass.

The styrene-based elastomer (A) is not limited to its effect, but is mainly used for increasing the cohesive force of the hot melt adhesive. By adjusting the styrene-based elastomer (A) to 10% by mass or more, cohesive force is imparted and performance as a hot melt adhesive can be obtained. Further, by setting the styrene elastomer (A) to 40% by mass or less, the hot melt adhesive can be applied without limitation on the coating machine. The content of the styrene-based elastomer (A) is preferably 15 to 35% by mass, and more preferably 15 to 25% by mass in the total of 100% by mass of (A) to (D).

Further, the rosin ester tackifier (B) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less is not limited to its effect, but mainly has a strong adhesive force with a base material or a PET bottle. Used to do. When the blending amount is 30% by mass or more, sufficient adhesive strength for sticking to the PET bottle can be exhibited. Further, when it is 55% by mass or less, tack can be expressed. The content of the rosin ester tackifier (B) is preferably 30 to 55% by mass in the total of 100% by mass of (A) to (D).

The process oil (C) having a pour point of −10 ° C. is not limited to its effect, but mainly has adhesion to a hot melt adhesive due to wettability and penetration with a base material or a PET bottle. Used to improve. When the blending amount is 10% by mass or more, the adhesiveness at low temperature and the peelability at low temperature are excellent. When it is 40% by mass or less, both cohesive force and adhesion can be achieved. The content of the process oil (C) is preferably 15 to 35% by mass in the total of 100% by mass of (A) to (D).

Further, the olefin copolymer (D) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less is not limited to its effect, but mainly improves hydrophilicity without inhibiting the adhesive strength. It is used to impart high alkali dispersibility. When the blending amount is 1% by mass or more, even the plastic film can be peeled off without adhesive residue in the NaOH aqueous solution. By setting the content to 20% by mass or less, both adhesive strength and alkali dispersibility can be achieved. The content of the olefin copolymer (D) is preferably 5 to 15% by mass in the total of 100% by mass of (A) to (D).

The hot melt adhesive of the present invention may contain components other than (A) to (D) as described later, but the total of (A) to (D) in 100% by mass of the hot melt adhesive is 90 to 100. It is by mass, preferably 95 to 100% by mass. When the total of the components other than (A) to (D) increases and the total of (A) to (D) becomes less than 90% by mass, the balance of adhesive strength, tack, and alkali dispersibility is lost.

In the hot melt adhesive of the present invention, a coloring material such as an antioxidant for preventing thermal deterioration and thermal decomposition, a fluorescent color former, and the like can be added, if necessary.

The hot melt adhesive of the present invention is produced, for example, by melting and blending (A) to (D) to form a homogeneous mixture. The melting and blending temperature is preferably 90 ° C. or higher and 180 ° C. or lower. If the melting temperature is less than 90 ° C., there is a problem that the blend is not uniform, while if it exceeds 180 ° C., problems such as browning due to thermal deterioration and thermal decomposition occur. As the device for blending, a well-known and known blending device such as a stirrer and an extruder can be used. At this time, the order of melting, blending method, melting, and blending may be arbitrary, but for example, first, a predetermined amount of process oil (C) and a pour point are charged into the blender container, melted, and stirred. , Styrene-based elastomer (A), rosin ester tackifier (B), and olefin-based copolymer (D) are sequentially added and blended to form a homogeneous mixture. Further, these may be kneaded at the same time by a twin-screw extruder.

<Plastic sheet with hot melt adhesive>
The hot melt adhesive of the present invention can be suitably used as a hot melt adhesive for adhering a sheet-shaped plastic used for a label or the like to various containers such as glass, plastic, and metal.
For example, specifically, by applying the hot melt adhesive of the present invention melted at a temperature of about 120 to 160 ° C. to the whole or a part of a plastic sheet processed into an arbitrary shape, the present invention The plastic sheet with the hot melt adhesive of the present invention can be obtained. Such a plastic sheet with a hot melt adhesive can be used as a POP label or a product display label.

Examples of the plastic sheet used include polyethylene, polypropylene, PET and the like. The thickness of the plastic sheet is not limited, but is preferably 10 to 120 μm. When it is 10 μm or more, the durability of the film can be ensured and it becomes difficult to tear, and when it is 120 μm or less, the flexibility of the film can be ensured and injury or the like can be prevented.

The plastic sheet with a hot melt adhesive of the present invention may be appropriately printed on the side opposite to the surface to which the adhesive is applied, that is, the surface of the plastic sheet, or the plastic sheet. It may be appropriately printed with a hot melt adhesive. In each case, the desired adhesive strength, holding power, peelability and hot alkaline water solubility are exhibited.
The printing may be performed on the entire surface or a part of the plastic sheet. The printing may be performed by any of conventionally known printing methods such as gravure printing and UV printing.

Examples of the hot melt adhesive application method include an open wheel method, a closed gun method, and a direct coat 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 or the like when peeled off.

<Container with plastic sheet>
The plastic sheet with a hot melt adhesive of the present invention can be suitably used as a POP label or a product display label applied to a container body.
For example, in the case of a POP label, the plastic label with the hot melt adhesive of the present invention can be attached to one surface of the container to obtain the container with the plastic label of the present invention.
In the case of a product label, the plastic label with the hot melt adhesive of the present invention is wrapped around the outer circumference of the container, the hot melt adhesive at one end is attached to the container, and the hot melt adhesive at the other end is attached. Can be affixed to the back of a plastic film to obtain the plastic labeled container of the present invention.
In addition to the above applications, it can be suitably used for attaching a sheet to a container for recycling.

Examples of the container include PET bottles for beverages and polyethylene, polypropylene, and polystyrene containers such as detergent containers.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

<Styrene-based elastomer (A)>
-Clayton G-1643 (manufactured by Kraton Polymer Co., Ltd.) (hereinafter abbreviated as "G1643") Styrene-ethylene / butylene-styrene block polymer (SEBS)
Melt viscosity * 1; 200 mPa · s
-Clayton G-1652 (manufactured by Kraton Polymer Co., Ltd.) (hereinafter abbreviated as "G1652") Styrene-ethylene / butylene-styrene block polymer (SEBS)
Melt viscosity * 1; 1,800 mPa · s

The melt viscosity * 1 is the melt viscosity of a styrene-based elastomer concentration 25% by mass toluene solution at 25 ° C. The melt viscosity was measured using a B-type viscometer RB80L (manufactured by Toki Sangyo Co., Ltd.), and the rotor No. No. 3 was used at an appropriate rotation speed.

<Rosin ester tackifier (B) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less>
-K-108 (manufactured by GUANGDONG KOMO) rosin ester, acid value: 170 mgKOH / g, softening point: 83 ° C.

<Process oil (C) with a pour point of -10 ° C or less>
-Diana Process PW-90 (manufactured by Idemitsu Kosan Co., Ltd.) (hereinafter abbreviated as "PW-90") Paraffin-based process oil (paraffin-based: 73%, naphthen-based: 27%, aromatic-based: 0%), Pour point: -15 ° C
-Diana Process PW-380 (manufactured by Idemitsu Kosan Co., Ltd.) (hereinafter abbreviated as "PW-380") Paraffin-based process oil (paraffin-based: 73%, naphthen-based: 27%, aromatic-based: 0%), Pour point: -15 ° C

<Olefin-based copolymer (D) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less>
-A-C5120 (Allied Chemical, copolymer of ethylene and acrylic acid), acid value: 120 mgKOH / g, melting point: 65 ° C.
-A-C5180 (Allied Chemical, copolymer of ethylene and acrylic acid), acid value: 180 mgKOH / g, melting point: 50 ° C or less

Other ingredients [Other tackifier (C)]
・ Haritac F (manufactured by Harima Chemicals, Inc.) Hydrogenated rosin, acid value 175 mgKOH / g, softening point: 72 ° C
-RE-85 (manufactured by Arizona Chemical Co., Ltd.) rosin ester, acid value 8 mgKOH / g, softening point: 85 ° C.
[Other oils (D)]
-Nippon Oil Polybutene HV-100 (manufactured by JX Nippon Oil Energy Co., Ltd.) (hereinafter abbreviated as "HV-100") Polybutene, pour point: -7.5 ° C.

(Example 1)
<How to make hot melt adhesive>
20 parts by mass of PW380: 20 parts by mass of process oil (C) having a pour point of −15 ° C. was charged into a stainless steel beaker equipped with a stirrer, and the mixture was heated and stirred. The heating was carried out carefully so that the contents did not exceed 150 ° C.
G1643: 10 parts by mass and G1652: 10 parts by mass are gradually added to this melt as the styrene elastomer (A), and after the addition is completed, the rosin ester having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less is next. 108: 50 parts of K was added as the tackifier (B), and finally, 10 parts by mass of AC5120: 10 parts as an olefin copolymer (D) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less was added. A melt-uniform mixture was prepared and cooled to prepare a hot-melt adhesive.

The alkali dispersibility, whitening, and adhesive strength of the obtained hot melt adhesive were evaluated by the following methods.
The alkali dispersibility, whitening, and adhesive strength of the hot melt adhesive of Example 1 were all ◯.

<Alkaline dispersibility>
Sample preparation method: Hot melt heated and melted at 150 ° C. was cut into 5 cm x 4 cm and applied to a PET film with a thickness of 75 μm so that the coating amount was 20 to 30 g / m ² and the coating area was 4 cm x 4 cm. Used to apply. After allowing to stand at room temperature for 24 hours, a label with a hot melt adhesive was obtained. A label with a hot melt adhesive was attached to a 2 L long-angle PET bottle to obtain a container to which the label with a hot melt adhesive was attached.
Next, the PET bottle together with the label with the hot melt adhesive was pulverized into about 8 mm × 8 mm square to obtain PET pellets with the label attached. It is desirable that there are 30 or more PET pellets.
Test method: 90 g of a 1.5 mass% sodium hydroxide aqueous solution at 85 to 90 ° C. and 10 g of the pellet were placed in a 1000 ml round flask and stirred at 600 rpm (stirring blade: propeller). After 15 minutes, the mixture was filtered through a filter, and the state of PET pellets was visually observed.
Evaluation criteria: ○ (good) when no hot melt adhesive remains on the PET pellets, △ (possible) when 1 to 3 hot melt adhesives remain on the PET pellets, and PET hot melt adhesive The case where 4 or more remained in the pellet was marked as x (defective).

<Whitening>
Sample preparation method: A label with a hot melt adhesive was obtained in the same manner as described above.
Test method: After aging in an oven at 40 ° C. for 1 week, the surface observation of the hot melt adhesive confirmed whether or not there was any change after aging as compared with before aging.
Evaluation Criteria: The case where the surface of the hot melt adhesive did not change was evaluated as ◯ (good), and the case where there was a change such as whitening or crystals compared to before aging was evaluated as × (poor).

<Adhesive strength>
Sample preparation method: A container to which a label with a hot melt adhesive was attached was cut into a width of 15 mm in the same manner as described above.
Test method: 180 degree angle peeling (peeling speed: 300 mm / min) was performed in each constant temperature room at 5 ° C., 23 ° C., and 40 ° C.
Evaluation criteria: ○ (good) when a value of 1.0 N / 15 mm or more is shown at all three temperatures, 0.8 N / 15 mm or more and less than 1.0 N / 15 mm at any one or more of the three temperatures. The case where the value of was shown was Δ (possible), and the case where the value less than 0.8 N / 15 mm was shown was x (defective).

(Examples 21 to 7, Comparative Examples 1 to 9)
A hot melt adhesive was prepared by melting and mixing in the same manner as in Example 1 with the compositions shown in Tables 1 and 2, and evaluated in the same manner.

From Examples 1 to 97 of Tables 1 and 2, it was shown that the hot melt adhesive of the present invention has excellent adhesive strength and alkali dispersibility and does not whiten. On the other hand, the hot melt adhesives of Comparative Examples 1 to 9 did not satisfy all of the adhesive strength, alkali dispersibility, and whitening.

The hot melt adhesive of the present invention can preferably use a POP label or a product display label, and can also be used for bonding handles.
The plastic label with a hot melt adhesive using the hot melt adhesive of the present invention can be suitably used for PET bottles, and can also be applied to other plastic containers, glass bottles, and the like. In addition, various containers can contain soft drinks, seasonings, detergents, shampoos, cooking oils, cosmetics, pharmaceuticals, and the like.

Claims (4)

The following (A) to (D) are contained in a total of 90 to 100% by mass in 100% by mass of the hot melt adhesive.
In the total of 100% by mass of the following (A) to (D),
Styrene-based elastomer (A): 10 to 35 % by mass,
Rosin ester tackifier (B) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less: 30 to 60% by mass,
Process oil (C) having a pour point of −10 ° C. or lower: 10 to 40% by mass, and an olefin copolymer (D) having an acid value of 100 mgKOH / g or more and 300 mgKOH / g or less: 1 to 20% by mass.
Including hot melt adhesive. The hot melt adhesive according to claim 1, wherein the olefin-based copolymer (D) is a copolymer of an olefin having 2 to 4 carbon atoms and (meth) acrylic acid. A plastic sheet with a hot melt adhesive, wherein the hot melt adhesive according to claim 1 or 2 is provided on opposite ends of the same surface of the quadrilateral plastic sheet. A container with a plastic sheet having the plastic sheet with the hot melt adhesive according to claim 3 on the outer periphery of the container.