JP2012236965A - Hot melt adhesive for heat-shrinkable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot melt adhesive for a heat-shrinkable film in which an adhesive layer does not flow at a temperature in which a heat shrinkage film performs heating shrink while being a thermoplastic adhesive, a wrinkle is not entered in a packaging material after heat shrinkage easily, hygiene is excellent, and the packaging material can be manufactured without requiring extra production equipment of an ultraviolet light source or the like.SOLUTION: The hot-melt adhesive for a heat-shrinkable film includes: 10-20 wt.% of an elastomer; 25-40 wt.% of a tackifier; 25-40 wt.% of a plasticizer; and 15-35 wt.% of a polypropylene wax having a softening point of at least 125°C and at most 165°C.

Description

  The present invention relates to a hot-melt pressure-sensitive adhesive for heat-shrinkable films used for packaging an article.

  In recent years, beverage containers such as polyethylene terephthalate bottles (hereinafter referred to as PET bottles) have been used in various shapes for the purpose of improving design properties, and plastic film labels have been used. In addition, a packaging material is used for a so-called multipack in which a plurality of articles are packaged together with a label of a single dry battery, and further with a dry battery, a health drink, and other beverage containers. Moreover, the packaging material is used so that the lid | cover of a pharmaceutical container and a drink container may be covered for the purpose of foreign material mixing prevention.

  In the packaging material including the label as described above, a heat shrink film is used as the packaging material in order to wrap articles having various shapes. Thermosetting adhesives and pressure-sensitive adhesives were used for this heat-shrinkable film, but the market is demanding environmental measures such as reducing the use of solvents and reducing carbon dioxide emissions, as well as reducing costs. It was. Therefore, for general label applications, hot melt adhesives and pressure-sensitive adhesives that satisfy the above requirements have been studied. However, a packaging material with an adhesive layer coated with a thermoplastic hot-melt adhesive on a heat-shrinkable film is softened when the packaging material is attached to the article and heated for shrinkage. Since it flows, there existed a problem in which an adhesive contaminates an article | item, or a packaging material removed from an article | item.

  Thus, a method has been proposed in which the adhesive layer is not flowed even when the packaging material is heated for heat shrinkage by making the hot melt adhesive into an ultraviolet curable type (see Patent Document 1).

JP 2008-145498 A

  However, the ultraviolet curable hot melt adhesive of Patent Document 1 has a problem in that the heat shrinkage of the heat shrinkable film does not match the cure shrinkage of the pressure-sensitive adhesive layer, and the packaging material is wrinkled. Moreover, when the printing layer was formed in the packaging material, there existed a problem that an ultraviolet-ray did not reach | attain an adhesive layer but hardening was inadequate. Moreover, since the ultraviolet curable hot melt adhesive requires an ultraviolet curable resin and a photopolymerization initiator as raw materials, there is a sanitary problem with food-related articles as packaging materials. In addition, the UV curable type has a problem that it requires an ultraviolet light source for curing and requires a new production facility.

  Although the present invention is a thermoplastic pressure-sensitive adhesive, the pressure-sensitive adhesive layer does not flow even at a temperature at which the heat-shrinkable film heat-shrinks, the packaging material does not easily wrinkle even after heat-shrinking, has good hygiene, and has no ultraviolet rays. An object of the present invention is to provide a hot-melt adhesive for a heat-shrinkable film that can produce a packaging material without requiring extra production facilities such as a light source.

  The present invention relates to a hot-melt adhesive for a heat-shrinkable film having a constitution containing 15 to 35% by weight of a polypropylene wax having a softening point of 125 ° C. or higher and 165 ° C. or lower, an elastomer, a tackifier, and 25 to 40% by weight of a plasticizer. It is an agent.

  According to the present invention having the above configuration, when a hot melt pressure-sensitive adhesive is heated and melted by coating by including a specific polypropylene wax, that is, when the temperature of the hot-melt pressure-sensitive adhesive decreases from a high temperature to a low temperature, The viscosity of the agent is low. When the heat-shrinkable film on which the pressure-sensitive adhesive layer is formed is heated to shrink, that is, when the temperature of the hot-melt pressure-sensitive adhesive rises from a low temperature to a high temperature, the pressure-sensitive adhesive layer does not flow and the film comes off. Or an effect that no deviation occurs. In addition, since the present invention is a thermoplastic hot-melt pressure-sensitive adhesive, it does not include a photopolymerization initiator contained in the ultraviolet-curable hot-melt pressure-sensitive adhesive and a polyfunctional monomer such as an acryloyl group. Excellent skin hygiene due to less skin irritation.

  According to the present invention, the pressure-sensitive adhesive layer does not flow even at a temperature at which the heat-shrinkable film is heat-shrinked, although it is a thermoplastic type, it is difficult for wrinkles to enter the packaging material even after heat-shrinking, good hygiene, ultraviolet light source etc. It was possible to provide a hot-melt adhesive for a heat-shrinkable film that can produce a packaging material without requiring an extra production facility.

Viscosity temperature curve of hot melt adhesive for heat shrinkable film An example of packaging material An example of packaging material Example of cylindrical packaging material Schematic diagram of a method for manufacturing articles with packaging materials using cylindrical packaging materials Schematic diagram of a method for manufacturing an article with packaging material using the packaging material of FIG. Schematic diagram of a method for manufacturing an article with packaging material using the packaging material of FIG. Schematic diagram of the packaging material attached to the article

The hot melt pressure-sensitive adhesive for heat-shrinkable film of the present invention comprises an elastomer, a tackifier,
It is preferable to include a plasticizer and 15 to 35% by weight of a polypropylene wax having a softening point of 125 ° C. or higher and 165 ° C. or lower.

  The elastomer is used for imparting a cohesive force to the hot melt adhesive. And since an adhesive is a hot-melt type, a thermoplastic elastomer is preferable. This elastomer preferably has heat-melting property and moderate condensing power. For example, olefin-based elastomer, vinyl chloride-based elastomer, polyester-based elastomer, polyurethane-based elastomer, nylon-based elastomer elastomer, acrylic-based, or styrene-based polymer is preferable. . Among these, styrenic elastomers are more preferable from the viewpoint of the balance between adhesive strength and cohesive strength.

  Styrenic elastomers generally have a polystyrene block and a rubber intermediate block. The polystyrene block forms a physical cross-link (domain) as a hard segment to serve as a bridging point, and the rubber intermediate block functions as a soft segment. Soft segments include polybutadiene (B), polyisoprene (I), and polyolefin elastomers (ethylene propylene, EP). Depending on the arrangement of the hard segment with polystyrene (S), linear (linear type) And radial (radical type). In the present invention, a styrene / butadiene block copolymer (SB, diblock), (SBS, triblock), styrene / isoprene block copolymer (SI, diblock), (S- IS, triblock) and styrene / butadiene-isoprene block copolymers (SB, I, diblock), (SB / IB, triblock) and hydrogenated products of these block copolymers For example, hydrogenated styrene / butadiene / styrene block copolymer (SBS), hydrogenated styrene / isoprene / styrene block copolymer (SEPS), styrene / hydrogenated poly (isoprene / butadiene) / styrene ( SEEPS), styrenic elastomer modified with carboxylic acid, and styrene in the styrene block When a copolymer of aromatic vinyl compounds such as α- methyl styrene. Among these, a styrene-ethylene / butylene-styrene block polymer copolymer (SEBS) is more preferable from the viewpoint of thermal stability (hard to be thermally decomposed).

  The elastomer preferably has a melt viscosity of 1 Pa · s to 10 Pa · s. When the melt viscosity of the elastomer is 1 Pa · s or more, the pressure-sensitive adhesive layer is hardly softened even at the heat shrink temperature of the film, so that the film is difficult to come off from the article. On the other hand, when the melt viscosity of the elastomer is 10 Pa · s or less, the viscosity when applying the hot-melt pressure-sensitive adhesive becomes appropriate, and a pressure-sensitive adhesive layer (hereinafter also referred to as a pressure-sensitive adhesive portion) is easily formed. In the present invention, the melt viscosity is a viscosity measured with a B-type viscometer at 25 ° C. in a solution of 25% by weight of an elastomer dissolved in toluene.

  The elastomer is preferably contained in an amount of 10% by weight to 25% by weight and more preferably 15% by weight to 20% by weight in 100% by weight of the hot melt adhesive. When the amount of the elastomer is 10% by weight or more, it becomes easy to balance the cohesive force and the adhesive force, and the heat shrinkage property is further improved. On the other hand, when the amount of the elastomer is 25% by weight or less, the viscosity at the time of applying the hot melt pressure-sensitive adhesive becomes more appropriate, so that the pressure-sensitive adhesive layer is easily formed. The heat shrinkage property means that a heat-shrinkable plastic film coated with a hot-melt adhesive is attached to a PET bottle and immersed in warm water at 90 ° C. for 3 seconds to shrink the film. Sometimes the label does not peel off or shift from the PET bottle.

  A tackifier is used in order to improve adhesive force. As tackifiers, phenol resins, modified phenol resins, terpene phenol resins, xylene phenol resins, xylene resins, cyclopentadiene-phenol resins, aliphatic resins, alicyclic resins, aromatic resins, etc., hydrogenated fats Aromatic, alicyclic and aromatic petroleum resins, phenol-modified petroleum resins, rosin ester resins, acid-modified rosin resins, hydrogenated rosin resins, hydrogenated rosin ester resins, low molecular weight polystyrenes Resins, terpene resins, hydrogenated terpene resins and the like are preferable. A tackifier may be used independently or 2 or more types may be used together.

  The tackifier is preferably contained in an amount of 25% by weight to 40% by weight in 100% by weight of the hot melt adhesive. Adhesive force improves more because the quantity of a tackifier becomes 25 weight% or more. On the other hand, when the amount of the tackifier is 40% by weight or less, it is easy to maintain the cohesive force of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is difficult to soften even at the heat shrink temperature of the film, so that the film is not easily detached from the article. Become.

The plasticizer is used for the purpose of obtaining an appropriate adhesive force even when the hot melt adhesive is used for a heat-shrinkable film and the film is attached to an article in a low temperature atmosphere. The plasticizer is not particularly limited as long as it satisfies the above characteristics, and liquid rubber ester plasticizers such as liquid polyisoprene, vegetable oil, liquid polybutene, or process oil are preferable. Among these, process oil is preferable from the viewpoint of physical property balance and price.
Process oil is produced in petroleum refining and the like, and examples thereof include paraffinic process oil, naphthenic process oil, and aromatic process oil. The process oil is a mixture of the above oils. Generally, the process oil contains 30% by weight or more of aromatic carbon in the total carbon, and the process oil contains 35 to 45% by weight of naphthenic ring carbon. Oils containing 50% by weight or more of paraffin chain carbon can be classified as paraffinic process oils. In the present invention, naphthenic process oil and paraffinic process oil are more preferable from the viewpoint of adhesive residue at the time of manual peeling because cohesive force is easily maintained in the pressure-sensitive adhesive layer.

  The plasticizer is preferably contained in an amount of 25% by weight to 40% by weight in 100% by weight of the hot melt adhesive. By containing the plasticizer in an amount of 25 wt% to 40 wt%, it becomes easy to balance the adhesive force between the low temperature atmosphere and the heat shrink temperature.

  It is important that the polypropylene wax has a softening point of 125 ° C. or higher and 165 ° C. or lower. Polypropylene wax is used for the purpose of increasing the difference between the viscosity when the temperature of the hot melt adhesive is raised and the viscosity when the temperature is lowered.

  When the softening point of the polypropylene wax is 125 ° C. or higher, it is easy to balance the adhesive force and the cohesive force at the heat shrink temperature. On the other hand, when the softening point is 165 ° C. or lower, since the viscosity of the pressure-sensitive adhesive is high, coating becomes difficult. The softening point was measured according to JIS K-2207 (petroleum asphalt) 6.4 softening point test method (ring and ball method).

  A typical synthesis method of polypropylene is 30 to 70 in a solvent (n-heptane or the like) in which propylene gas having a purity of 95% or more is added to a catalyst (Ziegler-Natta catalyst, for example, triethylenealuminum and titanium trichloride). When it is blown at a temperature, the polymerization reaction proceeds. After the polymerization, an alcohol is added to dissolve and remove the catalyst, whereby the polymer is obtained in the form of a white powder. Polymerization is carried out between normal pressure and 8 MPa, and the content of the isotactic polymer in the product varies depending on the type and concentration of the catalyst, the molar ratio of triethylaluminum to titanium trichloride, the reaction temperature, the time, and the like.

The polypropylene wax preferably has a molecular weight of 5,000 to 15,000, more preferably 6,000 to 8,000. When the molecular weight is 5,000 or more, it is easy to maintain the cohesive force of the adhesive even at the heat shrink temperature of the film. On the other hand, when the molecular weight is 15,000 or less, the coating suitability of the pressure-sensitive adhesive is easily maintained. The molecular weight was measured by a viscosity method. The measurement method is a measurement method utilizing the fact that the viscosity η of the polymer solution is a function of the average molecular weight as described below. Generally, the average molecular weight is referred to as the viscosity average molecular weight and is obtained by the following formula 1. .
Formula 1 η = kMα
(Where k and α are constants specific to the polymer)

  The polypropylene wax preferably contains 15 wt% or more and 35 wt% or less in 100 wt% of the hot melt adhesive. When the hot melt pressure-sensitive adhesive is 15% by weight or more, it becomes easy to obtain heat shrinkage characteristics. On the other hand, when the hot melt pressure-sensitive adhesive is 30% by weight or less, coating becomes easier.

  The hot-melt pressure-sensitive adhesive of the present invention is characterized in that the viscosity behavior during heating is different from the viscosity behavior during cooling. For example, when a hot melt pressure-sensitive adhesive is heated to 160 ° C. and then cooled to 25 ° C., the viscosity of the pressure-sensitive adhesive at 120 ° C. is 200 Pa · s or more and 50,000 Pa · s or less when heated, and 110 when cooled. The viscosity of the pressure-sensitive adhesive at 0 ° C. is preferably 0.1 Pa · s or more and 150 Pa · s or less. First, when applying a hot melt pressure-sensitive adhesive to a heat-shrinkable film, the pressure-sensitive adhesive is heated to 150 ° C. or higher and melted. In this case, the temperature of the pressure-sensitive adhesive is cooled from a high temperature to a low temperature, but coating is easy because of the low viscosity. On the other hand, when a packaging material coated with a hot-melt adhesive on a heat-shrinkable film is attached to an article and the film is shrunk by heating, the temperature of the adhesive is heated from low to high. Since the viscosity maintains a high viscosity, the pressure-sensitive adhesive does not flow with heat. That is, the packaging material does not come off from the article and does not shift.

The viscosity behavior of the hot melt adhesive will be described with reference to FIG.
When the hot melt pressure-sensitive adhesive is cooled from a high temperature (130 ° C. or higher in FIG. 1), the viscosity rises along two paths A and B along one path. Next, when the hot melt pressure-sensitive adhesive is heated from a low temperature (80 ° C. or lower in FIG. 1), it follows two paths, that is, a path different from that at the time of cooling. The inflection points C and D are shown, and the viscosity of the hot melt adhesive is lowered. As described above, the hot melt pressure-sensitive adhesive has different viscosity behaviors during cooling and heating, and the difference between them is large. That is, when applying a hot melt pressure-sensitive adhesive, the pressure-sensitive adhesive melts by heating once, the temperature of the pressure-sensitive adhesive is greatly reduced, and a pressure-sensitive adhesive layer can be formed on the heat-shrinkable film in a low viscosity state. On the other hand, when the film is heated to cause heat shrinkage, the temperature of the pressure-sensitive adhesive is increased, but its viscosity is difficult to decrease. An excellent effect that the material does not come off is obtained. In addition, the viscosity at the time of the said temperature fall and temperature rise is measured with the rheometer (The dynamic viscosity viscoelasticity measuring apparatus Rheosol-G3000 UBM Co., Ltd. make).

  In the hot melt pressure-sensitive adhesive of the present invention, for example, a plasticizer and an elastomer are charged into a container, heated and dissolved, and then a tackifier is charged. It can be manufactured by adding polypropylene wax after confirming that all of these have dissolved. When dissolving, it is preferable to use a propeller-type stirrer, and the rotation speed is preferably 200 to 500 rpm.

  The packaging material of the present invention has an adhesive part formed by applying a hot-melt adhesive for a heat-shrinkable film to at least one of the two right and left ends of the heat-shrinkable film. preferable. Specifically, it is preferable that an adhesive part is formed at one end (3-1) of the thermoplastic film as shown in FIG. 2, and both ends of the thermoplastic film (as shown in FIG. 3) It is also preferable that the adhesion part is formed in 3-1, 3-2). And at least one adhesive part (3-1) among the adhesive parts of FIG. 3 should just be formed from the hot-melt adhesive for heat-shrinkable films. Next, the pressure-sensitive adhesive that can be used to form the pressure-sensitive adhesive portion at the other end is a solvent-based or water-based pressure-sensitive adhesive selected from general hot-melt pressure-sensitive adhesives, acrylic-based, rubber-based, and urethane-based pressure-sensitive adhesives. preferable.

  Any heat-shrinkable film may be used as long as it has heat-shrinkability. In the present invention, a plastic film is preferred. The plastic film is more preferably a stretched polyester film, a stretched polystyrene film, a stretched polyolefin film, a polylactic acid film, a foamed polyolefin film, a stretched polyester-polystyrene coextruded film or a foamed polystyrene film. The plastic film may be provided with a vapor deposition film such as silicon oxide, aluminum oxide, or aluminum. The plastic film may be a non-woven fabric or a laminated film in which two or more films are bonded.

  The stretching includes uniaxial stretching and biaxial stretching. In the present invention, uniaxial stretching is preferred. The stretching direction of the uniaxially stretched film may be longitudinal uniaxial stretching or transverse uniaxial stretching.

  5-50 micrometers is preferable and, as for the thickness of a heat-shrinkable film, 10-30 micrometers is more preferable. Moreover, as for the thickness in the case of using the said laminated | multilayer film, 5-300 micrometers is preferable.

  The shrink temperature of the heat shrink film is not limited because it is determined by the shrink temperature of the film. Generally 70-140 degreeC is preferable.

The shrinkage ratio of the heat shrink film is preferably 5 to 85%. When the film shrinks to the above range, the article can be easily packaged. In addition, the heat shrinkage rate in this invention is a heat shrinkage rate when immersed in 100 degreeC warm water, Comprising: The heat shrinkage rate of an extending | stretching direction shall follow the following formula 2. Therefore, in the case of a longitudinally uniaxially stretched film, since the shrinking direction is the film flow direction, the thermal shrinkage rate in the flow direction is 5 to 85%, and in the case of a laterally uniaxially stretched film, the film shrinks in the film width direction. The heat shrinkage ratio in the film width direction is 5 to 85%. In the case of a biaxially stretched film, the thermal shrinkage rate is preferably within the above range with respect to any stretching method.
Formula 2 Thermal contraction rate (%) = (Dimension before heating−Dimension after heating) / (Dimension before heating) × 100

  In addition, various additives such as a lubricant, a filler, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, and a colorant may be added to the heat-shrinkable film as necessary. Good. Further, the surface of the base film layer may be subjected to conventional surface treatment such as corona discharge treatment, plasma treatment, flame treatment, acid treatment, etc. in order to improve printability.

  In order to form an adhesive part by applying hot melt adhesive to a heat-shrinkable film, a method of directly applying to a heat-shrinkable film, a hot-melt adhesive applied to a release sheet, A method of transferring to a film (hereinafter also referred to as transfer coating) is preferable.

  As a direct coating method, slit coating, curtain spray, spiral spray, dot or bead coating is preferable, and slit coating is more preferable.

  As a transfer coating method, roll coating and slit coating are preferred. Specifically, for example, after the hot melt adhesive is applied to the release sheet using a hand applicator, the formed adhesive portion can be transferred to a heat-shrinkable film.

  The hot melt pressure-sensitive adhesive is preferably heated to 130 to 200 ° C. and melted for coating. And 90-150 degreeC is preferable and, as for coating temperature, 110-140 degreeC is more preferable. When the coating temperature is less than 90 ° C., the hot melt pressure-sensitive adhesive has a high viscosity and is difficult to obtain stably. On the other hand, when the temperature is 150 ° C. or higher, the heat-shrinkable film shrinks during coating.

As for the thickness of an adhesion part, 10-200 micrometers is preferable. Moreover, when packaging a PET bottle, 10-200 g / m < ² > is more preferable.

  Moreover, 1-100 mm is preferable and, as for the width | variety of an adhesion part, 3-100 mm is preferable. In addition, the width | variety of an adhesion part is the length in the direction which wraps a packaging material around an article | item of an adhesive layer.

  The packaging material of the present invention is preferably used after packaging an article. The packaging aspect can package the entire article. It is also preferable to wrap a part of the article so as to wrap a part of the article, for example a cap part of a beverage bottle. Moreover, it is also preferable to use it as what is called a multipack which packages many articles collectively. The packaging material can wrap the entire article. It is also possible to wrap a part of an article, for example a cap part of a beverage bottle.

  The packaging material of the present invention can be produced by attaching the packaging material to the article and heating it. That is, it is preferable to have a step of attaching a packaging material to the outer periphery of the article, and then a step of shrinking the heat-shrinkable film by heating.

  Next, a method for attaching a packaging material to an article, that is, a method for producing an article with a packaging material will be described. However, the production method is merely an example, and the present invention is not limited to the following production method.

  The first aspect of the manufacturing method will be described by taking a PET bottle as an example of the article. The article will be described by taking a PET bottle as an example. The packaging material shown in FIG. 2 is used. The cylindrical packaging material shown in FIG. 4 can be obtained by overlapping the adhesive part (3-1) on the other end of the packaging material. Next, as shown in FIG. 5, a cylindrical packaging material is attached to the outer periphery (body portion) of the PET bottle. Furthermore, the process which shrinks a heat-shrinkable film can be performed by heating a packaging material mounting part.

  The second aspect of the manufacturing method will be described by taking a PET bottle as an example of the article. The packaging material shown in FIG. 2 is used. As shown in FIG. 6, the end portion of the packaging material where the adhesive portion is not formed is pressed against the outer periphery (body portion) of the PET bottle. Next, while wrapping the packaging material around the body of the PET bottle while pressing the end portion, the adhesive portion (3-1) is pasted so as to overlap the other end portion of the packaging material as shown in FIG. As shown, the process of attaching the packaging material is performed. Furthermore, it is preferable to perform the step (2-3) of shrinking the heat-shrinkable film by heating the packaging material mounting portion.

  A third aspect of the manufacturing method will be described by taking a PET bottle as an example of the article. The packaging material shown in FIG. 3 is used. First, as shown in FIG. 7, the adhesive part (3-2) is stuck on the outer periphery (body part) of the PET bottle. Next, the packaging material is wound around the body portion and attached so that the adhesive portion (3-1) overlaps the other end portion of the packaging material, so that the packaging material is attached as shown in FIG. . And it is preferable that the adhesion part (3-1) does not touch the trunk | drum of a PET bottle directly. Furthermore, the process which shrinks a heat-shrinkable film by heating a packaging material mounting part is performed.

  The heat shrinking step can be performed by heating with steam, hot air, hot water or the like. The heating temperature is preferably 80 to 110 ° C, and more preferably 80 to 95 ° C.

  In the present invention, articles include, for example, plastic bottles such as PET, glass bottles, can containers, packaging cups such as yogurt and pudding, dry batteries, media such as CDs and DVDs, and plastic cases that contain them, bottles, and heads of containers. Examples include shrink cap seals covered with parts, shrink capping of containers and packaging, shrink packs used in place of cardboard, and dry cell battery labels. These articles are also preferably filled with contents.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples. In the examples, “parts” simply means “parts by weight” and “%” means “% by weight”. “Wt%” means “wt%”.

  The raw materials used for the hot melt pressure-sensitive adhesive are as follows.

<Elastomer>
Kraton G1650 (manufactured by Kraton Polymer Co., Ltd.) (hereinafter abbreviated as “G1650”), composition: styrene-ethylene-butylene-styrene block polymer (SEBS), diblock amount: 0%, melt viscosity ^{* 1} : 8 Pa. s
Kraton G1652 (manufactured by Kraton Polymer Co., Ltd.) (hereinafter abbreviated as “G1652”), composition: styrene-ethylene-butylene-styrene block polymer (SEBS), diblock amount: 0%, melt viscosity ^{* 1} ; 350 Pa · s
Kraton G1730 (manufactured by Kraton Polymer Co., Ltd.) (hereinafter abbreviated as “G1730”), composition: styrene-hydrogenated polybutadiene-styrene block polymer (SEPS), melt viscosity ^{* 1} ; 2.0 Pa · s

The melt viscosity ^{* 1} is a melt viscosity at 25 ° C. of a toluene solution having a thermoplastic elastomer concentration of 25% by weight. The melt viscosity was measured using a B-type viscometer RB80L (manufactured by Toki Sangyo Co., Ltd.). 3 was carried out at a suitable rotational speed.

<Tackifier>
· Haritac F (manufactured by Harima Chemicals), composition: hydrogenated rosin, acid value: 175 mgKOH / g, softening point: 72 ° C
YS Polystar T30 (manufactured by Yasuhara Chemical Co., Ltd.) (hereinafter abbreviated as “T30”) Composition: terpene phenol resin, softening point: 30 ° C.

<Plasticizer>
Diana Fresia N90 (made by Idemitsu Kosan Co., Ltd.) (hereinafter abbreviated as “N90”) Composition: Paraffinic process oil

<Polypropylene wax>
NP-030 (Mitsui Chemicals, Inc.) molecular weight 5,800, softening point 153 ° C
NP-055 (Mitsui Chemicals, Inc.) molecular weight 7,000, softening point 148 ° C
NP-056 (Mitsui Chemicals, Inc.) molecular weight 7,000, softening point 131 ° C

<Removable hot melt>
Label melt P-708J (manufactured by Toyo Adre)

<Method for producing hot melt adhesive>
(Production Example 1)
A stainless beaker equipped with a stirrer was charged with 30 parts by weight of a plasticizer (N90), 15 parts by weight of an elastomer (G1652) and 5 parts by weight of a tackifier (T30), and heated to melt. Heating was performed with care so that the contents would not be below 130 ° C and above 150 ° C. After melting, stirring is performed to obtain a uniform molten solution, and while maintaining the temperature below 150 ° C. and continuing stirring, 35 parts by weight of a tackifier: Haritac F is gradually added to the melt, and after completion of the addition, 15 parts by weight of polypropylene wax (NP-030) was added to form a molten homogeneous mixture, and cooled to obtain a hot melt pressure-sensitive adhesive composition for heat shrinkable film.

(Production Examples 2 to 7)
Except having changed each raw material as described in Table 1, it carried out similarly to the manufacture example 1, and the hot-melt adhesive for heat-shrink films of the manufacture examples 2-7 was obtained.

(Comparative Production Examples 1 to 4)
Except having changed each raw material as described in Table 2, it carried out similarly to the manufacture example 1, and the hot-melt adhesive of the manufacture examples 2-7 was obtained.

<Paraffin wax>
-HNP-9 (Nippon Seiwa Co., Ltd.) molecular weight 500, softening point 75 ° C

<Measurement method of viscosity>
The viscosity of the obtained hot melt adhesive was measured using a plate type rheometer. The measurement method and measurement conditions are as follows. The measurement results are shown in Table 1.
・ Measuring device: Dynamic viscosity viscoelasticity measuring device Rheosol-G3000 (manufactured by UBM Co., Ltd. ・ Measurement mode: temperature dependence ・ Chuck: parallel plate ・ Waveform: sine wave ・ Parallel diameter: 19.99 mm
・ Cap: 1mm
-Temperature drop viscosity start temperature: 180 ° C Measurement end temperature: 30 ° C
・ Starting temperature measurement temperature: 30 ° C Measurement end temperature: 180 ° C
・ Cooling rate: 3 ° C./min ・ Cooling rate: 3 ° C./min ・ Rotation width: 2 Hz, 3 deg

<Method for producing packaging material 1>
The obtained hot-melt adhesive for heat-shrinkable film was heated to 150 ° C. and melted. The adhesive part 1 was formed by coating it on a release sheet using a hand applicator so as to have a coating thickness of 60 μm and a width of 15 mm. Subsequently, the said adhesive part was transcribe | transferred to the one edge part of the horizontal direction of the following heat-shrinkable film of the magnitude | size of length 17cm and width 22cm, and the packaging material 1 was obtained.

<Heat shrink film>
As the heat-shrinkable film, an MD direction uniaxially stretched polyethylene terephthalate film (manufactured by Toyobo Co., Ltd.) having a thickness of 20 μm was used.

<Method for producing packaging material 2>
A hot melt pressure-sensitive adhesive (product name: Toyomelt P-708K, manufactured by Toyo Adre Co., Ltd.) was heated to 150 ° C. and melted. The adhesive part 2 was formed by coating it on a release sheet using a hand applicator so as to have a coating thickness of 30 μm and a width of 15 mm. A packaging material 2 was obtained by transferring the adhesive part to the other end of the packaging material 1 where the adhesive part 1 was not formed.

(Examples 1-6)
<Manufacture of articles with packaging materials A>
The cylindrical packaging material was created by bonding the packaging material 1 with the adhesive part 1 on the inside so that all the parts of the adhesive part overlap the other end of the packaging material 1. Test sample 1 was obtained by mounting the cylindrical packaging material on the barrel of a cylindrical PET bottle having a circumference of 200 mm.

(Example 7)
<Manufacture of articles with packaging materials B>
The adhesive part 2 of the packaging material 2 was affixed on the trunk | drum of a cylindrical PET bottle with a circumference of 200 mm. Subsequently, the test sample 2 was obtained by winding around the outer periphery of the said PET bottle so that all the parts of the adhesion part 1 of the said packaging material 2 might overlap with the other edge part of the said packaging material 2. FIG.

(Comparative Examples 1-4)
The packaging material 1 was obtained by performing the hot-melt pressure-sensitive adhesive obtained in Comparative Production Examples 1 to 4 in the same manner as the production method of the packaging material 1 described above. Furthermore, the test sample 1 was obtained by carrying out similarly to manufacture A of the said article | item with a packaging material.

<Heat shrinkability test>
The obtained test samples 1 and 2 were immersed in a hot water bath heated to 90 ° C. to shrink the heat-shrinkable film, and the appearance was visually evaluated.
○: The deviation of the adhesive part 1 is 2 mm or less, and the packaging material does not peel off.
X: The shift | offset | difference of the adhesion part 1 was larger than 2 mm, or the packaging material peeled.

<Coating suitability and coating properties after stopping for 1 hour>
Using a melter series 3400 manufactured by Nordson, the temperature of the coating machine was set to 140 ° C, the hose temperature was 140 ° C, and the head temperature was 110 ° C. And the hot-melt adhesive obtained by the manufacture example was applied to the heat-shrinkable PET film at a coating speed of 20 to 150 m / min by a slit coater method. Separately, the coating was stopped for 1 hour, and the coating state was evaluated when the coating was performed again. The evaluation criteria are shown below.
○: Coating was possible without problems.
X: The coated surface was uneven. Or it could not be recoated. Or during re-coating, stringing of the adhesive occurred.

1: An example of the viscosity behavior of a hot-melt adhesive during cooling.
2: An example of the viscosity behavior of a hot-melt adhesive during heating.
3: Thermoplastic film 3-1: Adhesive part 1
3-2: Adhesive part 2
4: PET bottle

The present invention comprises 15 to 35% by weight of a polypropylene wax having a softening point of 125 ° C. or more and 165 ° C. or less, 10 to 25% by weight of a styrenic elastomer having polystyrene and rubber intermediate block, and 25 to 40% by weight of a tackifier. the process oil 25 to 40% by weight is including a heat-shrinkable film for hot melt adhesives.

The hot-melt pressure-sensitive adhesive for heat-shrinkable film of the present invention comprises a styrene-based elastomer having polystyrene and rubber intermediate block , a tackifier, a process oil, and a polypropylene wax having a softening point of 125 ° C. or higher and 165 ° C. or lower. It is preferable to contain 35% by weight.

A styrenic elastomer having polystyrene and rubber intermediate block is used to impart a cohesive force to the hot melt adhesive. And since an adhesive is a hot-melt type, a thermoplastic elastomer is preferable. The elastomer has preferably have a heat-meltable and moderate cohesion.

Process oil, when using hot melt adhesive to the heat-shrinkable film, when mounted in a low-temperature atmosphere the film to the article also, to use in order to obtain proper adhesion.
Flop Rosesuoiru is intended to be produced in petroleum refining and the like, paraffinic process oil, naphthenic process oil, aromatic type process oil. The process oil is a mixture of the above oils. Generally, the process oil contains 30% by weight or more of aromatic carbon in the total carbon, and the process oil contains 35 to 45% by weight of naphthenic ring carbon. Oils containing 50% by weight or more of paraffin chain carbon can be classified as paraffinic process oils. In the present invention, naphthenic process oil and paraffinic process oil are more preferable from the viewpoint of adhesive residue at the time of manual peeling because cohesive force is easily maintained in the pressure-sensitive adhesive layer.

The process oil is preferably contained in an amount of 25% by weight to 40% by weight in 100% by weight of the hot melt pressure-sensitive adhesive. By containing 25 wt% or more and 40 wt% or less of process oil , it becomes easy to balance the adhesive force between the low temperature atmosphere and the heat shrink temperature.

Claims (7)

10-25% by weight of elastomer,
Tackifier 25-40% by weight,
25 to 40% by weight of plasticizer,
A hot-melt adhesive for heat-shrinkable film, comprising 15 to 35% by weight of a polypropylene wax having a softening point of 125 ° C or higher and 165 ° C or lower.   The hot melt adhesive for heat-shrinkable film according to claim 1, wherein the polypropylene wax has a molecular weight of 5,000 to 15,000. When heating the adhesive to 160-200 ° C and cooling to 25 ° C,
When heated, the viscosity of the adhesive at 120 ° C. is 200 Pa · s or more and 50,000 Pa · s or less,
The hot melt adhesive for heat-shrinkable film according to claim 1, wherein the viscosity of the pressure-sensitive adhesive at 110 ° C. is 0.1 Pa · s to 150 Pa · s when cooled.   The packaging material provided with the adhesion part formed from the hot-melt-adhesive agent for heat-shrinkable films in any one of Claims 1-3 in the at least one edge part of a heat-shrinkable film. Attaching the packaging material according to claim 4 to the outer periphery of the article;
Then, the manufacturing method of the articles | goods with a packaging material which has the process of shrinking a heat-shrinkable film by heating. A step of forming a cylindrical packaging material by overlapping the adhesive portion of the packaging material according to claim 4 on the other end of the packaging material,
Next, a step of attaching the cylindrical packaging material to the article,
Furthermore, the manufacturing method of the articles | goods with a packaging material which has the process of shrinking a heat-shrinkable film by heating. The packaging which has the adhesion part 1 formed from the hot-melt-adhesive agent for heat-shrinkable films in any one of Claims 1-3 in one edge part of a packaging material, and the adhesion part 2 was formed in the other edge part A process of attaching the adhesive part 2 of the material to the article,
Next, the process of attaching the packaging material to the article by winding the packaging material around the outer periphery of the article and attaching the adhesive portion 1 so as to overlap the packaging material,
Furthermore, the manufacturing method of the articles | goods with a packaging material which has the process of shrinking a heat-shrinkable film by heating.

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