JP7244916B2 - hot melt adhesive - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hot-melt adhesive, and more particularly to a hot-melt adhesive suitable for fixing absorbent articles such as sanitary napkins and incontinence liners to clothing such as underwear and underwear (so-called positioning use).

An absorbent article is an article that is fixed to clothing such as underwear and underwear in order to absorb body fluids generated from the body such as menstrual blood, vaginal discharge, urine, and sweat. It is used to prevent discomfort and unsanitary conditions caused by adhesion to clothing.

As absorbent articles, for example, sanitary napkins, incontinence liners, puerperal shorts, mother's milk pads, perspiration side pads, paper diapers, pet sheets, hospital gowns, surgical gowns, and the like are known. Such absorbent articles are then provided with positioning adhesives to secure them to the garment and keep them in place during use.

Many absorbent articles generally consist of a moisture-permeable top sheet that comes into contact with the skin, a liquid-impermeable back sheet (generally a breathable polyethylene sheet) that comes into contact with clothing such as underwear and underwear, and an absorbent sandwiched between them. have. The absorbent article positioning adhesive is generally applied to the release base material and then transferred to the liquid-impermeable back sheet, and the absorbent article is removed by bringing the transferred positioning adhesive into contact with clothing. Affixed to the desired position of the garment, it will be held in that position.

If the positioning adhesive has insufficient holding power (adhesive strength and tackiness), the absorbent article may move from the attached position during use, and body fluids may adhere to the clothing. On the other hand, if the releasability of the positioning adhesive is insufficient, a portion of the adhesive may remain on the clothing when the absorbent article is removed after use (so-called "adhesive residue"). . Therefore, adhesives for positioning absorbent articles are required to be able to be adhered to clothing without shifting during use, and to be removable without adhesive residue on clothing after use.

Regarding adhesives for positioning absorbent articles, Patent Document 1 discloses a hot-melt adhesive for positioning absorbent articles containing a radial styrene block copolymer. US Pat. No. 5,300,008 discloses hot melt adhesives for positioning absorbent articles containing styrene-butadiene-styrene polymer (SBS) or styrene-isoprene-styrene polymer (SIS). Patent document 3 discloses a hot-melt adhesive for positioning absorbent articles containing a thermoplastic block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound.

JP 2016-65121 A Japanese Patent Publication No. 2017-503069 JP 2016-153448 A

By the way, in many cases, manufactured absorbent articles are stored in a warehouse or the like and then shipped in a planned manner. However, there is a problem that the adhesive permeates into the flexible polyethylene sheet and the holding power (adhesive strength and tackiness) of the adhesive is lowered. In addition, the positioning adhesive is temporarily stored in a tank at a temperature of around 180°C before it is applied to the release base material. has been pointed out. From these points of view, the positioning hot-melt adhesives of the prior art do not have sufficient performance and there is room for further improvement.

Therefore, the present invention provides a hot-melt adhesive suitable for positioning absorbent articles, having excellent thermal stability before coating, and a long period from commercialization to use of absorbent articles. However, the decrease in the holding power (adhesive strength and adhesiveness) of the adhesive is suppressed, and the absorbent article does not move from the position where it is attached to the clothing during use, and when it is removed from the clothing after use, it does not stick to the clothing. To provide a hot-melt adhesive that leaves no adhesive residue.

In addition, hereinafter, clothing such as underwear and underwear to which the hot-melt adhesive for positioning the absorbent article is attached is also referred to as "clothing to be worn".

As a result of intensive studies aimed at achieving the above objects, the inventors of the present invention have found that the above objects can be achieved with a hot-melt adhesive having a specific composition, and have completed the present invention.

1. A styrene-based thermoplastic elastomer A, a tackifying resin B, a plasticizer C, and an ethylene-containing vinyl copolymer D having a carbonyl bond,
The styrenic thermoplastic elastomer A is at least one selected from the group consisting of styrene-isoprene-styrene (SIS) copolymers and styrene-butadiene-styrene (SBS) copolymers,
The content of the styrenic thermoplastic elastomer A is 15 to 45% by mass,
When the mass part of the plasticizer C is C and the mass part of the vinyl copolymer D having an ethylene-carbonyl bond is D, the ratio represented by D / C is 0.22 to 0.80.
A hot-melt adhesive (excluding hot-melt adhesives containing acid-modified petroleum resins) characterized by:
2. 2. The hot melt adhesive according to item 1, wherein the vinyl copolymer D having an ethylene-carbonyl bond has an acid value of 5 or less even when it has an acid group in its structure.
3 . 3. The hot melt adhesive according to Item 1 or 2 , wherein the tackifying resin B is a hydrogenated petroleum resin.
4 . 4. The hot melt adhesive according to any one of items 1 to 3 , wherein the plasticizer C is a liquid plasticizer.
5. The hot-melt adhesive according to any one of items 1 to 4, which is used for positioning an absorbent article to clothing.

INDUSTRIAL APPLICABILITY The hot melt adhesive of the present invention is suitable for positioning of absorbent articles, has excellent thermal stability before coating, and is an adhesive even when the absorbent article is manufactured for a long period of time before use. The decrease in the holding power (adhesive strength and adhesiveness) of the absorbent article is suppressed, and the absorbent article does not shift from the position where it is attached to the clothing during use, and is attached when peeled off from the clothing after use. No adhesive residue on clothes.

The hot melt adhesive of the present invention contains a styrene-based thermoplastic elastomer A, a tackifying resin B, a plasticizer C, and a vinyl copolymer D having an ethylene-carbonyl bond,
When the mass part of the plasticizer C is C and the mass part of the vinyl copolymer D having an ethylene-carbonyl bond is D, the ratio represented by D / C is 0.10 to 0.80.
It is characterized by

The hot-melt adhesive of the present invention having the above characteristics is suitable for positioning of absorbent articles, has excellent thermal stability before coating, and has a long period from commercialization to use of absorbent articles. Even in such a case, the decrease in the holding power (adhesive strength and adhesiveness) of the adhesive is suppressed, and the absorbent article does not shift from the position where it is attached to the clothing during use, and can be peeled off from the clothing after use. There is no adhesive residue on the clothes to be worn.

Each component (A to D, etc.) of the hot melt adhesive of the present invention will be described below.

Styrene-based thermoplastic elastomer A
The hot-melt adhesive of the present invention contains a styrenic thermoplastic elastomer A.

Styrene-based thermoplastic elastomer A includes, for example, styrene-isoprene-styrene (SIS) copolymer, styrene-butadiene-styrene (SBS) copolymer, styrene-isobutylene-styrene (SIBS ^*1 ; Styrene-Isobutylene-Styrene ) copolymers, styrene-isoprene/butadiene-styrene (SIBS ^*2 ; Styrene-Isoprene/Butadiene-Styrene) copolymers, and hydrogenated products thereof.

The type of hydrogenation may be either complete hydrogenation (complete hydrogenation) or partial hydrogenation (partial hydrogenation), for example, styrene-ethylene-butylene-styrene (SEBS) copolymer, styrene-ethylene -propylene-styrene (SEPS) copolymer, styrene-ethylene-ethylene-propylene-styrene (SEEPS) copolymer, styrene-butylene-butadiene-styrene (SBBS) copolymer, and the like. Here, SEBS is the fully hydrogenated form of SBS. SEPS is the fully hydrogenated form of SIS. SEEPS is the fully hydrogenated form of SIBS ^*2 . SBBS is a partially hydrogenated product of SBS.

Among these styrenic thermoplastic elastomers A, at least one selected from SIS, SBS, SEBS and SBBS is preferred, and at least one of unhydrogenated SIS and SBS is particularly preferred.

The styrene thermoplastic elastomer A preferably has a styrene content of 10 to 50% by mass, more preferably 15 to 45% by mass. When the styrene content is 15% by mass or more, the cohesive force of the hot-melt adhesive is improved, and adhesive residue is less likely to occur. Further, when the styrene content is 45% by mass or less, the hot-melt adhesive becomes soft and easily exhibits adhesiveness even at low temperatures.

The styrene-based thermoplastic elastomer A preferably has a diblock ratio of 50 to 90% by mass, more preferably 65 to 80% by mass. When the diblock ratio is 50% by mass or more, the adhesive strength of the hot-melt adhesive is improved, making it easier to exhibit adhesiveness even at low temperatures. Further, when the diblock ratio is 90% by mass or less, the cohesive force of the hot-melt adhesive is improved, and adhesive residue is less likely to occur.

Although the weight average molecular weight (Mw) of the styrene-based thermoplastic elastomer A is not limited, it is preferably 30,000 to 400,000 for both the triblock copolymer and the diblock copolymer, and more preferably 40,000 to 350. ,000 is more preferred. When the weight-average molecular weight of the styrene-based thermoplastic elastomer A is 30,000 or more, the cohesive force of the hot-melt adhesive is improved, and adhesive residue is less likely to occur. Further, when the weight average molecular weight is 400,000 or less, the hot-melt adhesive becomes soft and easily exhibits adhesiveness even at low temperatures. In addition, the weight average molecular weight (Mw) of the copolymer in the present specification is a measured value obtained by conversion with standard polystyrene using a gel permeation chromatography measurement device.

The weight-average molecular weight (Mw) in the present invention can be measured, for example, using the following measurement apparatus and measurement conditions.
Measuring device: Product name “ACQUITY APC” manufactured by Waters
Measurement conditions: Column ACQUITY APC XT45 1.7 μm × 1 piece ACQUITY APC XT125 2.5 μm × 1 piece ACQUITY APC XT450 2.5 μm × 1 piece Mobile phase: Tetrahydrofuran 0.8 mL/min Sample concentration: 0.2 mass %
Detector: Differential refractive index (RI) detector Standard material: Polystyrene (manufactured by Waters, molecular weight: 266 to 1,800,000)
Column temperature: 40°C
RI detector temperature: 40°C

A commercially available product can be used as the SBS. For example, trade names "Asaprene T-438", "Asaprene T-439", and "Asaprene T-413" manufactured by Asahi Kasei Corporation can be mentioned. These can be used singly or in combination.

A commercially available product can be used as the SIS. For example, trade names "Quintac 3520", "Quintac SL-186" and "Quintac 3433N" manufactured by Nippon Zeon Co., Ltd., and trade names "D1161" manufactured by Kraton Co., Ltd. may be mentioned. These can be used singly or in combination.

A commercially available product can be used as the SEBS. For example, trade names "G1726" and "G1645" manufactured by Kraton Co., Ltd. are listed. These can be used singly or in combination.

A commercially available product can be used as the SBBS. For example, trade names "Tuftec P1500", "Tuftec P1083", and "Tuftec P5051" manufactured by Asahi Kasei Corporation can be mentioned. These can be used singly or in combination.

A commercially available product can be used for the SIBS. For example, product names such as "SIBSTAR073T", "SIBSTAR102T", and "SIBSTAR103T" manufactured by Kaneka Corporation can be mentioned. These can be used singly or in combination.

A commercially available product can be used as the SEPS. For example, trade names "SEPTON2063" and "SEPTON2005" manufactured by Kuraray Co., Ltd. may be mentioned. These can be used singly or in combination.

A commercially available product can be used as the SEEPS. For example, trade names such as "SEPTON4033" and "SEPTON4055" manufactured by Kuraray Co., Ltd. may be mentioned. These can be used singly or in combination.

The content of the styrene-based thermoplastic elastomer A in the hot-melt adhesive of the present invention is not limited, but is preferably 15-45% by mass, more preferably 20-40% by mass, based on 100% by mass of the hot-melt adhesive.

When the content of the styrene-based thermoplastic elastomer A in the hot-melt adhesive of the present invention is 15% by mass or more, the cohesive force of the hot-melt adhesive is improved, and adhesive residue is less likely to occur. Further, when the content of the styrene-based thermoplastic elastomer A is 45% by mass or less, the hot-melt adhesive becomes soft and easily exhibits adhesiveness even at low temperatures.

Tackifier resin B
The hot melt adhesive of the present invention contains a tackifying resin B. The tackifying resin B is not particularly limited, and examples thereof include rosin-based compounds, terpene-based compounds, and petroleum resins. Among these, terpene compounds and petroleum resins are preferred, and petroleum resins (especially hydrogenated petroleum resins) are particularly preferred.

Examples of the rosin-based compound include natural rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, and pentaerythritol ester of modified rosin.

Examples of the terpene-based compound include natural terpene copolymers, natural terpene three-dimensional polymers, hydrogenated derivatives of natural terpene copolymers, terpene resins, and hydrogenated derivatives of phenolic modified terpene resins.

Examples of the petroleum resin include petroleum resins such as C5-based petroleum resins, C9-based petroleum resins, C5C9-based petroleum resins, and dicyclopentadiene-based petroleum resins. Hydrogenated petroleum resins obtained by hydrogenating these petroleum resins (partially hydrogenated petroleum resins, fully hydrogenated petroleum resins) are also included. Among the hydrogenated petroleum resins, partially hydrogenated petroleum resins are more preferable because they have high compatibility with the styrene-based thermoplastic elastomer A and excellent heat stability. The C5 petroleum resin is a petroleum resin made from a C5 fraction of petroleum, the C9 petroleum resin is a petroleum resin made from a C9 fraction of petroleum, and the C5C9 petroleum resin is a C5 fraction of petroleum. and a C9 fraction as raw materials. C5 fractions include cyclopentadiene, isoprene, pentane, and the like. The C9 fraction includes styrene, vinyltoluene, indene, and the like. As the C5-based petroleum resin and the C5C9-based petroleum resin, those containing in the skeleton dicyclopentadiene (DCPD) derived from cyclopentadiene, which is a type of C5 fraction, are preferred.

As the tackifying resin B, petroleum resins (including partially hydrogenated petroleum resins and fully hydrogenated petroleum resins) are preferable because they are excellent in hot melt adhesive odor and thermal stability, and partially hydrogenated petroleum resins and Fully hydrogenated petroleum resins are more preferred.

Tackifying resin B can be used alone or in combination of two or more.

Although the softening point temperature of the tackifier resin B is not limited, it is preferably 90° C. or higher, more preferably 100° C. or higher. Although the upper limit of the softening point temperature is not limited, it is about 130°C. When the softening point of the tackifying resin B is 90° C. or higher, the hot melt adhesive of the present invention tends to exhibit its tackiness effect.

The content of the tackifying resin B in the hot-melt adhesive of the present invention is not limited, but is preferably 30-65% by mass, more preferably 40-60% by mass, based on 100% by mass of the hot-melt adhesive.

When the content of the tackifying resin B in the hot-melt adhesive of the present invention is 30% by mass or more, the adhesiveness of the hot-melt adhesive is improved and the adhesion to the adherend is improved. Moreover, when the content of the tackifying resin B is 65% by mass or less, the hot-melt adhesive becomes soft and easily exhibits holding power even at low temperatures.

Tackifying resin B can be used alone or in combination of two or more.

As the tackifying resin B, commercially available products can be used. Commercial products include, for example, "HA-085" manufactured by TonenGeneral Sekiyu, "HA-103" manufactured by TonenGeneral Sekiyu, "HB-103" manufactured by TonenGeneral Sekiyu, and "HB-125" manufactured by TonenGeneral Sekiyu. , Arakawa Chemical Co., Ltd. "Alcon P-90", Arakawa Chemical Co., Ltd. "Alcon M-100", Idemitsu Kosan Co., Ltd. "Imarb P100", Kolon Co., Ltd. "Scoretz SU400", Yasuhara Chemical Co., Ltd. "YS Resin TO-105" etc.

Plasticizer C
The hot melt adhesive of the present invention contains a plasticizer C. Although the plasticizer C is not limited, it is preferably a liquid plasticizer. The above-mentioned "liquid" means having fluidity at 25°C (that is, changing the shape according to the container when placed in a container).

The plasticizer C (especially liquid plasticizer) is not particularly limited, and examples thereof include polybutene, paraffinic process oil, naphthenic process oil, aromatic process oil, liquid paraffin, and hydrocarbon synthetic oil. Among these plasticizers C, at least one of polybutene and process oil is preferable. As the process oil, at least one of paraffinic process oil and naphthenic process oil is more preferred, and paraffinic process oil is particularly preferred from the viewpoint of enhancing flow resistance at high temperatures.

Plasticizer C can be used alone or in combination of two or more.

Polybutene is not particularly limited, and examples thereof include homopolymers of isobutene, copolymers of isobutene and n-butene, and the like.

A commercial item can be used as polybutene. Examples of commercially available products include "10N" manufactured by NOF, "Indopol H-100" manufactured by Ineos, "Nisseki Polybutene" manufactured by Nippon Petrochemical, "Tetrax" manufactured by Nippon Petrochemical and the like. .

A commercially available product can be used as the paraffinic process oil. Examples of commercially available products include "PW-32" manufactured by Idemitsu Kosan Co., Ltd., "Dianafrecia S32" manufactured by Idemitsu Kosan Co., Ltd., and "PS-32" manufactured by Idemitsu Kosan Co., Ltd.

A commercially available product can be used as the naphthenic process oil. Commercially available products include, for example, "KN4010" manufactured by PetroChina, "Diana Frecia N28" manufactured by Idemitsu Kosan, "Diana Frecia N90" manufactured by Idemitsu Kosan, "Diana Frecia U46" manufactured by Idemitsu Kosan, and "Diana Frecia" manufactured by Idemitsu Kosan. process oil NR” and the like.

A commercial product can be used as the aromatic process oil. Commercially available products include, for example, “Aromax” manufactured by Nippon Oil Co., Ltd.

Although the number average molecular weight of these process oils is not limited, it is preferably 200-700, more preferably 300-600.

Commercially available liquid paraffin can be used. Commercially available products include "P-100" manufactured by MORESCO and "Kaydol" manufactured by Sonneborn.

A commercially available product can be used as the hydrocarbon-based synthetic oil. Commercially available products include “Lucant HC-10” manufactured by Mitsui Chemicals, Inc. and “Lucant HC-20” manufactured by Mitsui Chemicals.

The content of the plasticizer C in the hot melt adhesive of the present invention is not limited, but is preferably 10 to 40% by mass, more preferably 15 to 35% by mass, based on 100% by mass of the hot melt adhesive. In the hot melt adhesive of the present invention, the ratio shown by D/C, where C is the mass part of the plasticizer C and D is the mass part of the vinyl copolymer D having an ethylene-carbonyl bond described later. should be between 0.10 and 0.80. Therefore, from the above point of view, it is necessary to define the content of the plasticizer C so that the ratio represented by D/C satisfies the above requirements. In the present invention, the hot-melt adhesive is excellent in thermal stability before coating, particularly because D/C is 0.10 to 0.80 (preferably 0.10 to 0.50), and Even when the absorbent article is manufactured for a long period of time before use, the decrease in adhesive holding power (adhesive strength and adhesiveness) is suppressed, and the position where the absorbent article adheres to the clothing during use No deviation.

When the content of the plasticizer C in the hot-melt adhesive of the present invention is 10% by mass or more, the cohesive force of the hot-melt adhesive is improved, and adhesive residue is less likely to occur. Moreover, when the content of the plasticizer C is 40% by mass or less, the hot-melt adhesive becomes soft and easily exhibits holding power even at low temperatures.

Ethylene-vinyl copolymer D having a carbonyl bond
The hot melt adhesive of the present invention contains vinyl copolymer D having an ethylene-carbonyl bond (hereinafter also referred to as "vinyl copolymer D").

Vinyl copolymer D is not limited as long as it has an ethylene-carbonyl bond, but examples include ethylene-vinyl acetate (EVA) copolymer, ethylene-methyl methacrylate (EMMA) copolymer, ethylene-acryl Ethyl acid (EEA) copolymers, ethylene-butyl acrylate (EBA) copolymers, ethylene-methyl acrylate (EMA) copolymers and the like can be mentioned.

The vinyl copolymer used in the present invention preferably has an acid value of 5 or less even if it has acid groups in its structure. Examples of acid groups include sulfonic acid groups and carboxylic acid groups. The acid value is preferably 5 or less, more preferably 3 or less.

The content of the vinyl copolymer D in the hot melt adhesive of the present invention is not limited, but is preferably 2 to 20% by mass, more preferably 3 to 15% by mass, based on 100% by mass of the hot melt adhesive. As described above, the present invention requires that the ratio represented by D/C is 0.10 to 0.80. Therefore, from the above point of view, it is necessary to define the content of the vinyl copolymer D so that the ratio represented by D/C satisfies the above requirements.

When the content of the vinyl copolymer D in the hot-melt adhesive of the present invention is 2% by mass or more, the cohesive force of the hot-melt adhesive is improved, and adhesive residue is less likely to occur. Moreover, when the content of the vinyl copolymer D is 20% by mass or less, the hot-melt adhesive becomes soft and easily exhibits adhesiveness even at low temperatures.

Optional Additives The hot melt adhesive of the present invention may contain various additives as required. Examples of various additives include stabilizers, particulate fillers, and the like.

Stabilizers are used to improve the stability of hot-melt adhesives by further improving the reduction in molecular weight, gelation, coloration, generation of odor, etc. of hot-melt adhesives due to heat. Specific types of stabilizers are not limited, but include, for example, antioxidants and UV absorbers.

Antioxidants are used to prevent oxidative deterioration of hot melt adhesives. In addition, ultraviolet absorbents are used to improve the light resistance of hot melt adhesives. Antioxidants and UV absorbers are generally used in disposable products, and the hot melt adhesive of the present invention is generally used as an adhesive for positioning disposable absorbent articles as described later. Since it is applied, it can be suitably used as an additive.

Examples of antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(4′-hydroxy-3′,5′-di-t-butylphenyl)propionate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 2,4-bis(octylthiomethyl)-o-cresol , 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,4-di-t-amyl-6-[1-(3 ,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)]acrylate, tetrakis[methylene-3-( 3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, dilauryl thiodipropionate, laurylstearylthiodipropionate, pentaerythritol tetrakis (3-laurylthiopropionate phosphate), phosphorus-based antioxidants such as tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, lactone-based antioxidants, and the like. . Examples of UV absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-t-butylphenyl)benzotriazole, 2-( Benzotriazole UV absorbers such as 2′-hydroxy-3′,5′-di-t-butylphenyl)-5-chlorobenzotriazole, benzophenone UV absorbers such as 2-hydroxy-4-methoxybenzophenone, salicylic acid Ester-based ultraviolet absorbers; cyanoacrylate-based ultraviolet absorbers; and hindered amine-based light stabilizers can be exemplified. These can be used alone or in combination.

A commercially available product can be used as the stabilizer. For example, the trade names "Sumisorb Sumilizer GM" and "Sumisorb 200" manufactured by Sumitomo Chemical Co., Ltd., the trade names "Irganox 1010" manufactured by BASF, and the trade names "JF-79" manufactured by Johoku Chemical Co., Ltd., etc. can be mentioned. be done. These commercially available stabilizers can be used alone or in combination.

Examples of particulate fillers include, but are not limited to, calcium carbonate, kaolin, talc, titanium oxide, mica, styrene beads, and the like. These particulate fillers can be used singly or in combination.

Physical Properties and Uses of Hot Melt Adhesive The hot melt adhesive of the present invention is useful as a hot melt adhesive for positioning absorbent articles, has excellent thermal stability before coating, and is used for absorbent articles. Even if the period from commercialization to use is long, the deterioration of the adhesive holding power (adhesive strength and adhesiveness) is suppressed, and the absorbent article does not shift from the position where it is attached to the clothing during use. In addition, there is no adhesive residue on the clothes when it is removed from the clothes after use.

From the standpoint of excellent thermal stability before coating, the hot melt adhesive of the present invention is, for example, put 20 g of the hot melt adhesive of the present invention in a glass bottle, leave it in an environment of 180 ° C. for 96 hours, and visually observe the hot melt adhesive. No precipitation of carbides is required on the surface of the melt adhesive.

Even if there is a long period from commercialization to use of the absorbent article, the deterioration of the holding power (adhesive strength and adhesiveness) of the adhesive is suppressed, and the absorbent article shifts from the position where it is attached to the clothing during use. From the viewpoint that there is no problem, the hot melt adhesive of the present invention is required to show good performance in predetermined shear strength tests (especially adhesive strength indicators) and probe tack tests (especially adhesiveness indicators). be.

Measurement samples for these tests (initial, after storage for 1, 2, and 4 weeks) are obtained, for example, by coating the hot-melt adhesive of the present invention on a release PET film so as to have a thickness of 25 μm. It can be produced by transferring onto a permeable polyethylene film, storing it in a 50° C. environment for 1, 2, or 4 weeks, and then attaching a polypropylene film to the back surface of the permeable polyethylene film for reinforcement.

In the shear strength test, the measurement sample was cut to a width of 35 mm (adhesion area 35 mm × 10 mm), and a 2 kg roller was applied to a JIS dyeing fastness test cotton cloth (Kanakin No. 3: simulated clothing) in accordance with JIS L 0803. It is required to be 5 N or more in each storage period when the actual value of shear strength is measured at a speed of 300 mm/min under an environment of 23° C. after laminating by reciprocating once.

The probe tack test can be measured under an environment of 23° C., for example, using a probe tack tester manufactured by Nichiban. A cylindrical SUS rod with a diameter of 5 mm was pressed against the adhesive of the measurement sample for each storage period with a load of 20 g and a contact time of 1 second, and then pulled up at a moving speed of 1 cm / sec. It is required to be 500g or more. Further, when the adhesive strength of the initial sample is assumed to be 100%, it is required that the adhesive strength retention rate is 60% or more for each storage time.

From the viewpoint that there is no adhesive residue on the clothing when it is removed from the clothing after use, the initial sample is cut to a width of 35 mm (adhesion area 35 mm × 10 mm), and the adhesive portion is JIS dyed in accordance with JIS L 0803. A cotton cloth for fastness test (Kanakin No. 3: simulated clothing) is placed, an acrylic plate of 60 mm × 100 mm × 2 mm thick is placed, and a load of 2.1 kg is applied on it for 2 hours. It is required that no adhesive residue is visually observed on the bonded surface of Kanakin when peeled at a speed of 1/min.

Examples of the absorbent article include, but are not limited to, sanitary napkins, incontinence liners, puerperal shorts, breast milk pads, perspiration side pads, disposable diapers, pet sheets, hospital gowns, surgical gowns, and the like. , can be applied to sanitary products in general that are mainly disposable and used for absorbing body fluids.

Absorbent articles are constructed by applying the hot-melt adhesive of the present invention to at least one member such as woven fabrics, non-woven fabrics, rubbers, resins, papers, and polyolefin films. As the polyolefin film, a polyethylene film is preferable from the viewpoint of durability and cost, and a breathable polyethylene film is generally used.

Among the absorbent articles, the hot melt adhesive of the present invention is suitable for sanitary napkins. A sanitary napkin generally has, for example, an absorbent body between a moisture-permeable topsheet and a liquid-impermeable backsheet, the topsheet contacting the skin, and the backsheet contacting underwear. A positioning adhesive is applied to the backsheet (substrate) to secure the sanitary napkin to the desired position on the undergarment. The hot-melt adhesive of the present invention exhibits particularly excellent effects when the back sheet of the sanitary napkin is a polyolefin film.

The method of applying the hot-melt adhesive to the base material of the absorbent article (the portion where the adhesive is provided) and the amount of application can be appropriately selected according to the type of absorbent article, and are not particularly limited. The coating method is roughly classified into contact coating and non-contact coating. Contact coating refers to a coating method in which the ejector is brought into contact with the substrate when coating the hot melt adhesive. Non-contact coating refers to a coating method in which the jetting machine does not come into contact with the base material when coating the hot-melt adhesive.

Examples of contact coating methods include slot coater coating and roll coater coating. Non-contact coating methods include, for example, spiral coating capable of spiral coating, omega coating or control seam coating capable of wavy coating, and slot spray coating or curtain spray coating capable of planar coating. Dot coating, etc., which can be applied in dots, can be exemplified.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the examples. In addition, Example 7 is a reference example.

Examples 1-7 and Comparative Examples 1-5
The hot melt adhesives of Examples 1 to 7 and Comparative Examples 1 to 5 were obtained by mixing each component (A to D) shown in Table 1 and melt-kneading them using a stirrer at about 150° C. for about 1 hour. was prepared.

Details of components AD are provided below.
(A1-1) Styrene-butadiene block copolymer "Asaprene T-438 (trade name)" manufactured by Asahi Kasei Corporation (styrene content 35% by mass, diblock ratio 70% by mass, Mw: triblock copolymer 120,000, diblock block copolymer 56,000)
(A1-2) Styrene-butadiene block copolymer "Asaprene T-439 (trade name)" manufactured by Asahi Kasei Corporation (styrene content 45% by mass, diblock ratio 60% by mass, Mw: triblock copolymer 85,000, diblock Block copolymer 44,000)
(A1-3) Styrene-butadiene block copolymer "Asaprene T-413 (trade name)" manufactured by Asahi Kasei Corporation (styrene content 30% by mass, diblock ratio 80% by mass, Mw: triblock copolymer 300,000, diblock block copolymer 70,000)
(A2-1) Styrene-isoprene block copolymer “Quintac 3520 (trade name)” manufactured by Nippon Zeon (styrene content 15% by mass, diblock ratio 78% by mass, Mw: triblock copolymer 350,000, diblock block copolymer 150,000)
(A2-2) Styrene-isoprene block copolymer “Quintac SL-186 (trade name)” manufactured by Nippon Zeon (styrene content 24% by mass, diblock ratio 65% by mass, Mw: triblock copolymer 160,000 , diblock copolymer 100,000)
(A3) Styrene-ethylene-butylene block copolymer Kraton "G1726 (trade name)" (styrene content 30% by mass, diblock ratio 70% by mass, Mw: triblock copolymer 59,000, diblock copolymer Combined 31,000)
(A4) Styrene-butylene-butadiene block copolymer Asahi Kasei Corporation "Tuftec P1500 (trade name)" (styrene content 30% by mass, diblock ratio 70% by mass, Mw: triblock copolymer 100,000, diblock copolymer Polymer 50,000)
(B1) Tackifier resin Hydrogenated petroleum resin “HB-103 (trade name)” manufactured by Tonen (ring and ball softening point 100 ° C.)
(B2) Tackifier resin Hydrogenated petroleum resin “HA-103 (trade name)” manufactured by Tonen (ring and ball softening point 100 ° C.)
(C1) Plasticizer Polybutene manufactured by NOF Co., Ltd. “Polybutene 10N (trade name)”
(C2) plasticizer paraffin oil “PS-90 (trade name)” manufactured by Idemitsu Kosan Co., Ltd.
(C3) Plasticizer PetroChina naphthenic oil "KN-4010 (trade name)"
(D1) Ethylene-vinyl acetate copolymer Honeywell EVA wax "ACP-400 (trade name), vinyl acetate content 13%"
(D2) Ethylene-vinyl acetate copolymer EVA manufactured by Tosoh Corporation "Ultrathen U685 (trade name), vinyl acetate content 14%"
(D3) Comparative product LDPE manufactured by Sumitomo Chemical Co., Ltd. “Sumikasen CE3506 (trade name)”
(D4) Comparative product FT wax “FT105 (trade name)” manufactured by Nippon Seiro Co., Ltd.

Test example 1
For each hot-melt adhesive obtained in Examples and Comparative Examples, thermal stability before coating, initial, adhesive holding power (adhesive strength and adhesiveness) after storage for 1, 2, and 4 weeks, and initial The presence or absence of adhesive residue in the adhesive was investigated. Each evaluation method and evaluation criteria are shown below.

[Thermal stability before coating]
20 g of each hot-melt adhesive was placed in a glass bottle, left in an environment of 180° C. for 96 hours, and then visually observed to see if precipitation of carbide was observed on the surface of the hot-melt adhesive.
○: Precipitation of carbide is not observed ×: Precipitation of carbide is observed

[Shear strength test of adhesive at initial stage, after storage for 1, 2 and 4 weeks]
Test measurement samples (initial, after storage for 1, 2, and 4 weeks) were each hot melt adhesive coated on a release PET film to a thickness of 25 μm, and transferred onto an air permeable polyethylene film. After storage for 1, 2, and 4 weeks in a 50° C. environment, a polypropylene film was adhered to the rear surface of the permeable polyethylene film for reinforcement.

In the shear strength test, the measurement sample was cut to a width of 35 mm (adhesion area 35 mm × 10 mm), and a 2 kg roller was applied to a JIS dyeing fastness test cotton cloth (Kanakin No. 3: simulated clothing) in accordance with JIS L 0803. The sheets were pasted together by reciprocating once, and the actual value of the shear strength was measured at a speed of 300 mm/min under an environment of 23°C. ○ or above is acceptable.
◎: 10 N or more ○: 5 N or more and less than 10 N △: 3 N or more and less than 5 N ×: less than 3 N

[Initial, probe tack test of adhesive after storage for 1, 2, 4 weeks]
Measured with a probe tack tester manufactured by Nichiban in an environment of 23°C. A columnar SUS rod with a diameter of 5 mm was pressed against the adhesive of the measurement sample for each storage period with a load of 20 g for a contact time of 1 second, and then pulled up at a moving speed of 1 cm/sec to measure the strength. ○ or above is acceptable.
◎: 1000 g or more ○: 500 g or more and less than 1000 g △: 300 g or more and less than 500 g ×: less than 300 g

[Presence or absence of adhesive residue]
Cut the initial sample to a width of 35 mm (adhesion area 35 mm × 10 mm), place a cotton cloth for JIS dyeing fastness test (Kanakin No. 3: simulated clothing) in compliance with JIS L 0803 on the adhesive part, and measure 60 mm × 100 mm × An acrylic plate with a thickness of 2 mm was placed and a load of 2.1 kg was applied to it for 2 hours. Then, when peeled at a speed of 300 mm/min in an environment of 23°C, adhesive residue was visually observed on the bonded surface of KANAKIN. I checked if there is.
○: Adhesive residue is not observed △: Adhesive residue is partially observed (level of acceptable range without practical problems)
×: A lot of adhesive residue is observed

Tables 1 and 2 also show the test results and evaluation results.

As is clear from the results in Table 1, the hot-melt adhesives of Examples 1 to 7 of the present invention are excellent in thermal stability before coating and have a long period from commercialization of absorbent articles to use. Even in such cases, the decrease in the holding power (adhesive strength and adhesiveness) of the adhesive is suppressed, and the absorbent article does not shift from the position where it is attached to the clothing during use, and when it is removed from the clothing after use, the absorbent article does not adhere to the clothing. It can be seen that there is no adhesive residue. On the other hand, the hot-melt adhesives of Comparative Examples 1 to 5 show a decrease in adhesive holding power (adhesive strength and tackiness) when the period from commercialization of absorbent articles to use is long. .

Claims (5)

A styrene-based thermoplastic elastomer A, a tackifying resin B, a plasticizer C, and an ethylene-containing vinyl copolymer D having a carbonyl bond,
The styrenic thermoplastic elastomer A is at least one selected from the group consisting of styrene-isoprene-styrene (SIS) copolymers and styrene-butadiene-styrene (SBS) copolymers,
The content of the styrenic thermoplastic elastomer A is 15 to 45% by mass,
When the mass part of the plasticizer C is C and the mass part of the vinyl copolymer D having an ethylene-carbonyl bond is D, the ratio represented by D / C is 0.22 to 0.80.
A hot-melt adhesive (excluding hot-melt adhesives containing acid-modified petroleum resins) characterized by: 2. The hot melt adhesive according to claim 1, wherein the vinyl copolymer D having ethylene-carbonyl bonds has an acid value of 5 or less even if it has acid groups in its structure. 3. The hot melt adhesive according to claim 1 , wherein the tackifying resin B is a hydrogenated petroleum resin. The hot melt adhesive according to any one of claims 1 to 3 , wherein said plasticizer C is a liquid plasticizer. 5. The hot melt adhesive according to any one of claims 1 to 4, which is used for positioning purposes for fixing absorbent articles to clothing.