Melting bag, mass, hot melt sheet, and hot melt laminate using the same

Abstract

To provide a melting bag for a hot-melt adhesive which is excellent in workability such as crushing resistance and deformation easiness when it is packed, and is excellent in compatibility to a content when it is used, a hot-melt sheet using the same, and a hot-melt laminate.SOLUTION: A melting bag is formed from a resin composition which contains at least a styrenic elastomer (A) and has melt viscosity at 160°C of 30,000 mPa s or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to melt bags, blocks, hot melt sheets, and hot melt laminates that are suitable for use in packaging hot melt adhesives. [Background technology]

[0002] Hot melt adhesives are melted and bonded to objects, and then cooled down, and the adhesive function is immediately apparent, so the advantage of not needing a curing period has been rediscovered, and their use in packaging and industrial applications is expanding. In response to recent social changes that emphasize reducing the burden on the environment, the advantage of not needing a solvent or drying process during use has also been rediscovered, and their use is continuing to expand.

[0003] As the range of application of hot melt expands, there is a demand for improved workability. In the summer, hot melt blocks stick together (blocking), and when removing them from the cardboard boxes in which they are packed, they become huge blocks, which significantly reduces workability. In particular, hot melt adhesives that are adhesive at room temperature are packed, transported, and stored wrapped in release paper or film, which is peeled off and discarded when the hot melt is to be used. However, the disposal of these release materials has also come to be seen as an environmental burden.

[0004] Therefore, a specification called a melting bag was developed in which hot melt is packaged in a hard material and the hot melt is melted while still packaged when it is used (Patent Document 1). This avoids the environmental burden of disposing of the release material, and also eliminates the work of peeling off the release material every time a lump of hot melt is melted, dramatically improving work efficiency.

[0005] In recent years, measures have been taken to prevent blocking by increasing the strength of the melting bag (Patent Document 2) or embossing the shape (Patent Document 3). However, these methods have a large deviation from the properties of the hot melt content, and the compatibility between the melting bag and the hot melt in the melting furnace is insufficient, resulting in a problem that the mixed melt supplied to the coating head does not have the designed ratio. In addition, because the strength of the melting bag is too high, when a mass of hot melt adhesive wrapped in the melting bag is packed in a cardboard box or the like, the mass cannot change shape, resulting in a low-density package that does not meet the desired filling amount. However, if the strength of the melting bag is made extremely weak in order to impart ease of deformation, the mass will break during packaging, causing the hot melt adhesive to come out to the surface, resulting in a problem of blocking between the masses.

[0006] An example of a hot melt adhesive that exhibits adhesiveness at room temperature is a hot melt adhesive used for labels attached to PET bottles. In order to recycle PET bottles, the PET bottles and the labels must be separated by immersing them in a heated alkaline aqueous solution, so alkaline dispersibility is required for hot melt adhesives for PET bottle labels. Since contamination with foreign matter is undesirable in food and beverage applications, sufficient compatibility between the melting bag and the hot melt having alkaline dispersibility is required. After the inventors of the present invention conducted research, they found that there was a problem with the compatibility of conventional melting bags with hot melt having alkaline dispersibility. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2004-002581 A [Patent Document 2] International Publication No. 2014 / 194087 [Patent Document 3] JP 2019-065164 A Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an object of the present invention is to provide a melting bag which is superior to conventional bags in terms of workability during packaging, such as shatter resistance and ease of deformation, and which also has excellent compatibility with the contents during use, and which is suitable for use in packaging hot melt adhesives, as well as a mass, hot melt sheet, and hot melt laminate which use the same. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, one embodiment of the present invention is a melt bag containing at least a styrene-based elastomer (A) and having a melt viscosity at 160°C of 30,000 mPa·s or less.

[0010] Another embodiment of the present invention is the melt bag, wherein the content of the styrene-based elastomer (A) is 70 mass% or less in 100 mass% of a resin composition forming the melt bag.

[0011] Another embodiment of the present invention is the melt bag described above, which contains at least a styrene-ethylene-butylene-styrene block copolymer as the styrene-based elastomer (A).

[0012] Another embodiment of the present invention is the melt bag described above, wherein the styrene-based elastomer (A) has a weight average molecular weight of 300,000 or less.

[0013] Another embodiment of the present invention is the melt bag, which is for packaging hot melt adhesive.

[0014] Another embodiment of the present invention is a mass in which a hot melt adhesive is packaged in a melt bag, the melt bag being the mass described above.

[0015] Another embodiment of the present invention is the above lump, wherein the difference between the softening point of the hot melt adhesive and the softening point of the melting bag is within 50°C.

[0016] Another embodiment of the present invention is a hot melt sheet which is a sheet-shaped product of the above-mentioned lump.

[0017] Another embodiment of the present invention is the hot melt sheet, which has a ball tack of 4 or more at a thickness of 25 μm.

[0018] Another embodiment of the present invention is a hot melt laminate comprising the hot melt sheet and an adherend disposed in this order. Effect of the Invention

[0019] According to the present invention described above, it is possible to provide a melting bag that is suitable for use in packaging hot melt adhesives, which has superior workability during packaging, such as crush resistance and ease of deformation, and further has excellent compatibility with the contents during use, as well as a mass, hot melt sheet, and hot melt laminate using the same. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a schematic cross-sectional view partially showing the lump of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The melt bag, hot melt sheet, and hot melt laminate that are preferably used for packaging the hot melt adhesive of the present invention will be described in more detail below, but are not limited thereto. The melting bag containing the hot melt adhesive is called a lump. Note that the term "hot melt adhesive" includes hot melt pressure sensitive adhesives. In this specification, a numerical range specified by using "~" includes the numerical values ​​before and after "~" as the lower and upper limit values. In this specification, hot melt adhesives may be abbreviated as "hot melt". In addition, unless otherwise noted, each of the various components appearing in this specification is independently one type. However, two or more of them may be used in combination. Moreover, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0022] <Melting bag> The melt bag of the present invention is preferably used for packaging hot melt adhesives, but is not limited thereto as long as it can contribute technically to articles other than hot melt adhesives. The melt bag can be produced by heating and melting a material (resin composition) containing at least the styrene-based elastomer (A) and forming a film (manufacturing) using a known method.

[0023] The melt viscosity (mPa·s) of the melt bag at 160°C is 30,000 or less. It is preferably 25,000 or less, more preferably 20,000 or less. It is also preferably 1,000 or more, more preferably 2,000 or more, and even more preferably 3,000 or more. Although the influence of the film thickness must be taken into consideration, by having the melt viscosity within the above range, it is easy to achieve both crush resistance and compatibility. In this specification, the melt bag and the resin composition differ in whether or not a film is formed, but are otherwise the same, so the preferred properties of the melt bag can be read as the properties of the resin composition.

[0024] The softening point of the melting bag is preferably 50° C. or higher, more preferably 60° C. or higher, even more preferably 70° C. or higher, particularly preferably 80° C. or higher, and most preferably 95° C. or higher. Also, it is preferably 150° C. or lower, more preferably 130° C. or lower, even more preferably 110° C. or lower, and particularly preferably 100° C. or lower. When the softening point is within the above range, crush resistance and blocking resistance are easily exhibited. The softening point is measured in accordance with JIS K-2207 (petroleum asphalt) 6.4 Softening point test method (ring and ball method).

[0025] The thickness of the melting bag is preferably 25 to 500 μm, more preferably 50 to 500 μm, further preferably 50 to 300 μm, and particularly preferably 50 to 200 μm. By keeping the thickness within the above range, it is easy to achieve both crush resistance and ease of deformation.

[0026] The amount of volatile organic compounds (VOCs) contained in the melting bag is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and preferably substantially free. By keeping the amount of VOCs within the above range, the melting bag is easily adapted to applications where hygiene is important, such as the food and medical industries.

[0027] ≪Resin composition≫ In the present invention, the resin composition refers to a material for forming a melt bag, and contains at least a styrene-based elastomer (A). It is preferable that the resin composition further contains a process oil (B) and a tackifier (C). The inclusion of the process oil (B) provides excellent compatibility and ease of deformation, and the inclusion of the tackifier (C) provides excellent resistance to crushing, which is preferable.

[0028] <Styrene-based elastomer (A)> Styrene-based elastomer (A) is a type of thermoplastic elastomer. Thermoplastic elastomers are elastic materials that have the same properties as vulcanized rubber at room temperature, and at high temperatures, they are polymeric materials that can be molded using existing molding machines, just like ordinary thermoplastic resins. Thermoplastic elastomers have both elastic rubber components (soft segments: soft phase) in the molecules and molecular restraint components (hard segments: hard phase) to prevent plastic deformation, so they have properties between rubber and plastic. Styrene elastomers generally have a polystyrene block and a rubber middle block, the polystyrene part forms a physical crosslink (domain) and becomes a crosslinking point, and the middle rubber block gives the product rubber elasticity. The middle soft segment includes polybutadiene (B), polyisoprene (I) and polyolefin elastomers (ethylene-propylene (EP), ethylene-butylene (EB), butylene-butadiene (BB)), and depending on the arrangement with the hard segment polystyrene (S), they are divided into linear type and branched type (radial type).

[0029] Examples of styrene-based elastomers include styrene-butadiene-styrene block copolymer (hereinafter sometimes abbreviated as SBS), styrene-ethylene-butylene-styrene block copolymer (including hydrogenated SBS, hereinafter sometimes abbreviated as SEBS), styrene-ethylene-propylene-styrene block copolymer (hereinafter sometimes abbreviated as SEPS), styrene-isoprene-styrene block copolymer (hereinafter sometimes abbreviated as SIS), styrene-butylene-butadiene-styrene block copolymer (hereinafter sometimes abbreviated as SBBS), etc. Among them, from the viewpoint of crush resistance, it is preferable to contain styrene-ethylene-butylene-styrene block copolymer or styrene-butylene-butadiene-styrene block copolymer, and it is more preferable to contain styrene-ethylene-butylene-styrene block copolymer.

[0030] The styrene content of the styrene elastomer (A) is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, and even more preferably 20 to 40% by mass. When the styrene content is within this range, it becomes easier to balance the strength that exhibits crush resistance and the flexibility that exhibits ease of deformation. The styrene content is the content (mass%) of styrene in 100% by mass of the styrene elastomer.

[0031] The weight average molecular weight (Mw) of the styrene-based elastomer (A) is preferably 10,000 to 300,000, more preferably 50,000 to 200,000, further preferably 80,000 to 150,000, and particularly preferably 100,000 to 150,000. By setting the molecular weight within the above range, it is easy to achieve both crush resistance and ease of deformation. The weight average molecular weight is a value calculated as polystyrene by measuring by gel permeation chromatography (GPC).

[0032] The content of the styrene-based elastomer (A) is preferably 1 to 70 mass%, more preferably 3 to 60 mass%, further preferably 5 to 50 mass%, and particularly preferably 10 to 45 mass%, based on 100 mass% of the resin composition. By containing the styrene-based elastomer (A) in the above range, it is easy to achieve both crush resistance and ease of deformation.

[0033] <Process oil (B)> Process oil (B) is generally used as a plasticizer for rubber, thermoplastic elastomers, etc. It is a process oil produced in so-called oil refineries, etc., and is roughly classified into paraffinic process oil, aromatic process oil, and naphthenic process oil. Process oil is a mixture of paraffin chains, aromatic rings, and naphthenic rings, and is classified as paraffinic process oil when the paraffin chain carbon of the total carbon is 50 mass% or more, aromatic process oil when the aromatic carbon of the total carbon is 30 mass% or more, and naphthenic process oil when the naphthenic ring carbon of the total carbon is 30 mass% or more.

[0034] The content of the process oil (B) is preferably 5 to 90 mass%, more preferably 10 to 80 mass%, further preferably 15 to 70 mass%, particularly preferably 20 to 60 mass%, based on 100 mass% of the resin composition. By containing the process oil (B) in the above range, the ease of deformation is excellent.

[0035] <Tackifier (C)> The tackifier (C) is a polymer with a relatively low molecular weight, ranging from several hundred to several thousand. It exhibits liquid or solid properties at room temperature, and adding the tackifier imparts fluidity and tackiness, improving adhesive strength. In the present invention, there are no particular limitations as long as it is solid at room temperature. If it is solid at room temperature, it has excellent resistance to crushing, while also playing a role in raising the adhesive strength, which is its original function, when used as a hot melt.

[0036] Tackifiers (C) are broadly classified into natural resin-based and synthetic resin-based. Natural resin-based agents include rosin-based resins and terpene-based resins, while synthetic resin-based agents include petroleum-based resins, phenol-based resins, and xylene-based resins. Either tackifier can be used alone or in combination depending on the application.

[0037] The tackifier (C) preferably contains at least one of fully hydrogenated petroleum resin and partially hydrogenated petroleum resin. By containing at least one of fully hydrogenated petroleum resin and partially hydrogenated petroleum resin, the crush resistance is excellent. Since fully hydrogenated petroleum resin and partially hydrogenated petroleum resin do not have aromatic rings that increase the affinity between molecules, it is considered that they tend not to block. At first glance, the use of tackifier (C) in the melting bag itself may be perceived as an act that goes against the role of the melting bag, but it is preferable to use it from the viewpoint of compatibility with the hot melt adhesive contained therein.

[0038] The content of the tackifier (C) is preferably from 0 to 50 mass%, more preferably from 0 to 45 mass%, and even more preferably from 5 to 40 mass%, in 100 mass% of the resin composition. By containing the tackifier (C) in the above range, it is easy to achieve both crush resistance and ease of deformation while adjusting the amount of the process oil (B). From the viewpoint of compatibility, the content of the tackifier (C) or the process oil (B) or the total content of these is preferably 30 mass% or more, more preferably 40 mass% or more, and even more preferably 45 mass% or more, based on 100 mass% of the resin composition.

[0039] To the extent that the problem of the present invention can be solved, waxes such as polyethylene wax, polypropylene wax, Fischer-Tropsch wax, paraffin wax, and microcrystalline wax, α-methylstyrene resin, and other thermoplastic elastomers can be used as components contained in the resin composition that forms the melt bag. Other examples of thermoplastic elastomers include olefin-based, urethane-based, polyester-based, polyamide-based, and 1,2-butadiene-based elastomers. If necessary, antioxidants, age resistors, etc. may be added to prevent thermal deterioration and thermal decomposition.

[0040] [Production of resin composition] The resin composition can be prepared by compounding and mixing the above-mentioned materials while heating in a known manner. Diluting the composition with an organic solvent increases workability, but places restrictions on application, so it is preferable to avoid using organic solvents whenever possible.

[0041] <Lump> The lump is a hot melt adhesive packaged in a melting bag. The weight is preferably 10 g to 5000 g. If the weight is within the above range, it is easy to handle and has excellent workability in terms of the number of times it can be filled, which is preferable. The thickness of the melting bag can be appropriately adjusted depending on the weight. After forming (manufacturing) the melt bag, a mass can be obtained by filling it with hot melt adhesive so that as little air as possible gets in. From the viewpoint of energy efficiency, this process is preferably cooled immediately after forming the film or carried out underwater.

[0042] (Hot melt adhesive) For example, when the hot melt adhesive is intended for adhesive applications, it is preferable that the resin system contains a styrene-based elastomer, which makes it easier to exhibit various adhesive properties. As the styrene-based elastomer, the same materials as those used in the resin composition for manufacturing the melt bag described above can be used. In terms of compatibility in a melting furnace, it is more preferable to use the same type of material as the resin composition. Specifically, it is preferable to contain a styrene-based elastomer (A), a process oil (B), and a tackifier (C). The types of the styrene-based elastomer (A), the process oil (B) and the tackifier (C) can be appropriately selected depending on the application of the hot melt.

[0043] In the case of a hot melt for PET bottle labels, since releasability by an alkaline aqueous solution is required, the tackifier (C) preferably has a high acid value of 100 mgKOH / g or more. The upper limit of the acid value is preferably 400 mgKOH / g. The acid value of the hot melt adhesive is preferably 15 to 100 mgKOH / g. The content of the tackifier having an acid value is preferably 0.1 to 70 mass% in 100 mass% of the hot melt adhesive, more preferably 1 to 60 mass%, further preferably 15 to 55 mass%, and particularly preferably 25 to 50 mass%. The higher the acid value, the lower the content can be. In addition, for environmentally friendly products, a tackifier with a high biomass degree of 80% or more is preferred.

[0044] The softening point of the hot melt adhesive is preferably 40° C. to 110° C., more preferably 50° C. to 100° C., and even more preferably 60° C. to 90° C. A hot melt adhesive having a softening point within the above range exhibits tackiness at room temperature, and therefore has excellent compatibility with melting bags while enjoying the advantages of being made into a mass, and also easily exhibits cohesive force when used as a hot melt.

[0045] The softening point of the hot melt adhesive is preferably within 70° C. of the softening point of the melting bag, more preferably within 50° C., even more preferably within 30° C., and particularly preferably within 20° C. The difference between the softening point of the hot melt adhesive and the softening point of the melting bag is within the above range, resulting in excellent compatibility between the two.

[0046] <Hot melt sheet> The hot melt sheet is a sheet-shaped product of a lump, which can be produced by melting the lump in a melting furnace and forming it into a sheet by any coating method.

[0047] The coating method is not particularly limited, but any known method can be used. Examples include the open wheel method, the closed gun method, and the direct coat method. When emphasis is placed on removability depending on the application, the open wheel method and the direct coat method are preferred. The thickness of the hot melt sheet varies depending on the application, but is generally in the range of 10 μm to 1000 μm.

[0048] The ball tack of the hot melt sheet is not particularly limited, but for label applications such as food packaging, the ball tack at a thickness of 25 μm is preferably 4 or more. A ball tack of 4 or more is preferable because sufficient adhesive strength can be obtained. The method for measuring the ball tack is described in detail in the Examples section.

[0049] <Hot melt laminate> The hot melt laminate is a laminate in which a hot melt sheet and an adherend are arranged in this order. There are no particular limitations on the manufacturing method, but it can be obtained by (a) a method in which a hot melt is applied to the release-treated surface of a release-treated film to prepare a hot melt sheet with a release film, and an adherend is laminated on the surface of the hot melt layer, (b) a method in which a hot melt is directly applied to the adherend, and the release-treated surface of the release-treated film is laminated on the surface of the hot melt layer, or (c) a method in which the release film is peeled off from the laminate obtained by (a) or (b), and an adherend is further laminated on the surface of the hot melt layer.

[0050] (adherent) The adherend is not particularly limited, but plastic, nonwoven fabric, and paper can be suitably used. Examples of plastics include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic resins such as polymethyl methacrylate (PMMA), and other plastic materials such as polycarbonate, triacetyl cellulose, polysulfone, polyarylate, and polycycloolefin. Examples of nonwoven fabrics include nonwoven fabrics made of hydrophilic fibers such as cotton and rayon, and nonwoven fabrics made of synthetic resin fibers that have been subjected to a hydrophilic treatment. Examples of paper include Yupo paper, coated paper, wood-free paper, and cardboard. The adherends may be used alone or in combination of two or more kinds.

[0051] Applications of the hot melt laminate are not particularly limited, but include food labels, hygiene products such as diapers and sanitary products, and bonding materials used in personal computers, cameras, and medical equipment. EXAMPLES

[0052] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the examples, unless otherwise specified, "parts" means "parts by mass", "%" means "% by mass", and "RH" means relative humidity. The blending amounts in the tables are in parts by mass. Note that blanks in the tables indicate that no blending was performed.

[0053] [Weight average molecular weight] The weight average molecular weight (Mw) was measured using a GPC "LC-GPC system" manufactured by Shimadzu Corporation. The weight average molecular weight (Mw) can be determined by conversion using polystyrene with a known molecular weight as a standard substance. Device name: Shimadzu Corporation, LC-GPC system "Prominence" Column: Four GMHXL columns manufactured by Tosoh Corporation and one HXL-H column manufactured by Tosoh Corporation were connected together. Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0ml / min Column temperature: 40℃

[0054] [Melt flow rate (MFR)] The MFR was calculated in accordance with JIS K7210 by filling a sample into a cylinder of a Melt Indexer L244 (manufactured by Takara Kogyo Co., Ltd.) with an inner diameter of 9.55 mm and a length of 162 mm, melting it at 190°C, and then applying an even load using a plunger weighing 2160 g and having a diameter of 9.48 mm to the sample, and calculating the amount of resin extruded per unit time (g / 10 min) from an orifice with a diameter of 2.1 mm located in the center of the cylinder.

[0055] The abbreviations used in Tables 1 to 4 are as follows: [Styrene-based elastomer (A)] G1642: Kraton G1642 (Kraton Polymers, SEBS, styrene content: 21% by mass, weight average molecular weight: 124,000) G1650: Kraton G1650 (Kraton Polymers, SEBS, styrene content: 30% by mass, weight average molecular weight: 96,000) A1536: Kraton A1536 (Kraton Polymers, SEBS, styrene content: 42% by mass, weight average molecular weight: 135,000) G1726: Kraton G1726 (Kraton Polymers, SEBS, styrene content: 30% by mass, weight average molecular weight: 46,000) D1161: Kraton D1161 (Kraton Polymers, SIS, styrene content: 15% by mass, weight average molecular weight: 180,000)

[0056] [Process oil (B)] PW-90: Diana Process PW-90 (Idemitsu Kosan, paraffin-based process oil)

[0057] [Tackifier (C)] P-100: Alcon P-100 (Arakawa Chemical Co., Ltd., hydrogenated petroleum resin, softening point: 100°C) Haritac F (Harima Chemicals, hydrogenated rosin type, acid value: 170 mg KOH / g, softening point: 80°C)

[0058] [wax] Sasol H1 (manufactured by Sasol Chemical Industries, Fischer-Tropsch wax, softening point: 112°C) Sasol C80 (manufactured by Sasol Chemical Industries, Fischer-Tropsch wax, softening point: 88°C)

[0059] [Other thermoplastic elastomers] LDPE: Low density polyethylene (melting peak temperature 107℃, density 0.919g / cm 3 , MFR4g / 10min) EVA: Ethylene-vinyl acetate copolymer (vinyl acetate content 28% by mass, MFR 6g / 10min)

[0060] Example 1 <Production of Resin Composition P-1> In a stainless steel beaker equipped with a stirrer, 30 parts of wax: Sasol H1 and 20 parts of PW-90 as process oil (B) were added and melted by heating. The heating was performed carefully so that the contents would be at 130 to 150°C. After melting, the mixture was stirred to make a homogeneous molten liquid, and then 10 parts of G1642 as a styrene-based elastomer (A) was added to the melt while maintaining the temperature at 130 to 150°C and continuing to stir. After the addition was completed, the mixture was heated and stirred at a temperature of 130 to 150°C to completely melt G1642. Then, 40 parts of tackifier (C): P-100 was added to make a molten homogeneous mixture, which was then cooled to prepare resin composition P-1. After adjusting the resin composition P-1 to 160°C, it was measured at an appropriate rotation speed using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., "RB80L") and rotor No. 3. The melt viscosity of resin composition P-1 at 160°C was 500 mPa·s.

[0061] <Manufacture of hot melt adhesive Q-1> In a stainless steel beaker equipped with a stirrer, 5 parts of wax: Sasol C80 and 40 parts of PW-90 as process oil (B) were added and heated to melt. Heating was performed carefully so that the contents would reach 130 to 150°C. After melting, stirring was performed to obtain a homogeneous molten liquid, and then 25 parts of G1726 as a styrene-based elastomer (A) was added to the molten liquid while maintaining the temperature at 130 to 150°C and continuing to stir. After the addition was completed, the mixture was heated and stirred at a temperature of 130 to 150°C to completely melt G1726. Then, 30 parts of Haritac F was added as a tackifier (C) to obtain a homogeneous molten mixture, which was then cooled to produce hot melt adhesive Q-1. <Production of melt bag and lump 1> Next, resin composition P-1 was placed in a melt bag molding machine and set to form a melt bag with a thickness of 200 μm under the condition of a temperature of 100° C. 500 g of hot melt adhesive Q-1 was extruded toward the molten film while being heated, and molded so as to encase it in water. After cooling in the water as it is, lump 1 was obtained.

[0062] <Manufacturing of hot melt sheets> The obtained lump 1 was melted for 1 hour in a melting furnace heated to 160°C, and coated onto the release agent layer of a heavy release film so that the thickness of the sheet after formation was 25 µm to form a hot melt sheet. Next, the release agent layer of a light release film was bonded to this hot melt layer to obtain a hot melt sheet.

[0063] (Examples 2 to 20, Comparative Example 1) Hot melt adhesives (Q-2 to 6) were produced in the same manner as in Example 1, except that the compositions and amounts (parts by mass) were changed to those shown in Table 1, and resin compositions (P-2 to 20, P'-1) were produced in the same manner as in Example 1, except that the compositions and amounts (parts by mass) were changed to those shown in Tables 2 to 4, and their melt viscosities at 160°C were measured. Subsequently, in the same manner as in Example 1, the hot melt was filled into a melt bag to obtain lumps and hot melt sheets of Examples 2 to 20 and Comparative Example 1. In Tables 1 to 4, melt viscosity at 160° C. is abbreviated as 160° C. viscosity, hot melt as HM, styrene-based elastomer as elastomer, process oil as oil, tackifier as TF, and wax as WAX.

[0064] [Table 1]

[0065] [Table 2]

[0066] [Table 3]

[0067] [Table 4]

[0068] <Ball tuck> The resulting hot melt sheet was prepared to a size of 25 mm wide and 250 mm long. The light release film was removed from the hot melt sheet and it was fixed to an inclined plate with an inclination angle of 30 degrees, and the heavy release film was removed to place the adhesive side facing up. A PET film for the runway was attached to the top, and a steel ball (1 / 32 to 32 / 32 inches) was rolled over the sample with a runway of 10 cm and an adhesive surface of 10 cm, and the diameter number of the ball that stopped near the center of the adhesive surface was recorded.

[0069] <Easy to deform> The ease of deformation (deformability) of the obtained lump was evaluated using a rubber hardness tester Type A (a durometer hardness tester manufactured by Shimadzu Corporation) The evaluation criteria were as follows: [Evaluation Criteria] ◎: Measurement scale is 20 points or less, excellent. ○: Measurement scale is between 20 and 30 points, good. △: Measurement scale is between 30 and 40 points, no practical problems. ×: The measurement scale is over 40 points, which is problematic for practical use.

[0070] <Crush resistance> A release film was laid on a small piece of cardboard, molten hot melt adhesive was poured onto it, and the adhesive was allowed to cool naturally and harden to produce a flat-surfaced block of hot melt adhesive. A melting bag (10 cm square, 200 μm thick) was then laminated on top of the resulting block of hot melt adhesive, and a melting bag (10 cm square, 200 μm thick) and block of hot melt adhesive were then laminated on top of that in that order to produce a block of hot melt adhesive / melting bag / / melting bag / block of hot melt laminate. A 10 kg weight was placed on the laminate, and it was stored at 40°C for 24 hours. After cooling in the air, the melting bags were peeled apart by hand to evaluate the crush resistance. The evaluation criteria are as follows: [Evaluation Criteria] ◎: No peeling sound or peeling strength, excellent. Good: Slight peeling sound, some peeling strength, good. △: Blocking occurred, but the molten bag did not break even when peeled off, and there was no problem in practical use. ×: Blocking occurred and the melted bag would break when peeled off, which would be problematic in practical use.

[0071] <compatibility> A white melting bag was prepared by mixing 1% by mass of titanium oxide with respect to the total mass of the melting bag, and this was used to prepare a white mass. The compatibility of the white melting bag and the hot melt adhesive in the melting furnace when preparing a hot melt sheet from the obtained white mass was evaluated based on the white unevenness of the hot melt sheet. The evaluation criteria are as follows. [Evaluation Criteria] ◎: No color unevenness, excellent. ◯: Good, with some color unevenness in some areas. △: Although color unevenness was observed overall, there was no remaining melted part in the melting bag, and there was no problem in practical use. ×: Color unevenness was observed overall, and melted bags remained. Problematic for practical use.

[0072] From the results in Tables 2 to 4, the aggregates of Examples 1 to 20 were excellent in workability during packaging and transportation, such as crush resistance and ease of deformation, and furthermore, the melting bags had excellent compatibility with the contents when used. On the other hand, the aggregate of Comparative Example 1 did not satisfy all of the above characteristics. [Explanation of symbols]

[0073] 1 Melting Bag 2. Hot melt adhesives

Claims

1. A mass of hot melt adhesive packed in a melt bag, The melt bag contains at least a styrene-based elastomer (A) and has a melt viscosity at 160°C of 30,000 mPa·s or less, The softening point of the melting bag is higher than the softening point of the hot melt adhesive; A lump that is not wrapped in a release material.

2. The mass described in claim 1, wherein the hot melt adhesive is a hot melt adhesive used for PET bottle labels.

3. 3. The lump according to claim 1, wherein the styrene-based elastomer (A) contains at least a styrene-ethylene-butylene-styrene block copolymer.

4. The softening point of the melting bag is 50°C or higher and 150°C or lower, 3. The lump according to claim 1, wherein the softening point of the hot melt adhesive is 40°C or higher and 110°C or lower.

5. The mass according to claim 1 or 2, wherein the hot melt adhesive has an acid value of 15 to 100 mg KOH / g.

6. The hot melt adhesive contains at least a tackifier having an acid value, and the content of the tackifier having an acid value is 0.1 to 70 mass% in 100 mass% of the hot melt adhesive.

7. A lump as described in claim 1 or 2, wherein the difference between the softening point of the hot melt adhesive and the softening point of the melting bag is within 50°C.

8. A hot melt sheet which is a sheet-shaped product of the lump according to claim 1 or 2.

9. 9. The hot melt sheet according to claim 8, which has a ball tack of 4 or more at a thickness of 25 μm.

10. A hot melt laminate comprising the hot melt sheet according to claim 8 and an adherend, disposed in this order.

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