阅读说明：本技术 伸缩性热熔组合物 (Stretchable hot melt composition ) 是由 染谷悠 于 2019-01-31 设计创作，主要内容包括：本发明提供一种伸长性和伸长后的伸缩恢复性优异、在伸长时显示适度的应力、而且加热稳定性优异、能够利用通常所使用的热熔粘接剂涂布装置涂布的伸缩性热熔组合物。本发明提供一种含有热塑性弹性体(A)和塑化剂(B)的伸缩性热熔组合物,上述热塑性弹性体(A)含有苯乙烯系嵌段共聚物的氢化物,上述伸缩性热熔组合物100质量％中,含有45～75质量％的热塑性弹性体(A)、5～40质量％的塑化剂(B),上述伸缩性热熔组合物的180℃时的熔融粘度为40,000mPa·s以下。(The invention provides a stretchable hot melt composition which is excellent in extensibility and stretch recovery after elongation, exhibits appropriate stress when elongated, is excellent in heat stability, and can be applied by a hot melt adhesive application device which is generally used. The invention provides a stretchable hot melt composition comprising a thermoplastic elastomer (A) and a plasticizer (B), wherein the thermoplastic elastomer (A) contains a hydrogenated product of a styrene-based block copolymer, the stretchable hot melt composition contains 45 to 75 mass% of the thermoplastic elastomer (A) and 5 to 40 mass% of the plasticizer (B) per 100 mass%, and the melt viscosity of the stretchable hot melt composition at 180 ℃ is 40,000 mPas or less.)

1. A stretchable hot melt composition comprising a thermoplastic elastomer (A) and a plasticizer (B), characterized in that,

the thermoplastic elastomer (A) contains a hydrogenated product of a styrenic block copolymer,

the stretchable hot melt composition comprises, based on 100% by mass, 45-75% by mass of a thermoplastic elastomer (A) and 5-40% by mass of a plasticizer (B),

the melt viscosity of the stretchable hot-melt composition at 180 ℃ is 40000 mPas or less.

2. A stretchable hot melt composition according to claim 1,

the thermoplastic elastomer (A) contains a styrene-ethylene/butylene/styrene-styrene copolymer.

3. A telescopic hot melt composition according to claim 1 or 2,

and 5 to 35% by mass of a wax (C) having at least 1 group selected from a carbonyl group, a carboxyl group and a carboxylic anhydride group in the molecule.

4. A telescopic hot melt composition according to any one of claims 1 to 3,

a tan value of 1.5 or less at a temperature at which a loss tangent tan measured at a frequency of 1Hz during temperature rise reaches a maximum value in a dynamic viscoelasticity measurement at-60 ℃ to-20 ℃,

the loss tangent tan is the loss modulus G ″/storage modulus G'.

5. A stretchable laminate obtained by bonding a nonwoven fabric to at least one surface of the stretchable hot melt composition according to any one of claims 1 to 4.

Technical Field

The present invention relates to a stretchable hot melt composition.

Background

In recent years, sanitary materials such as disposable diapers and sanitary napkins have been widely used, and in these sanitary materials, stretchable laminates made of stretchable members have been used in order to prevent slippage when worn.

As a member having stretchability used for a stretchable laminate, a rubber thread formed by forming a natural rubber or a synthetic polymer into a thread shape is known. The rubber thread exhibits good stress when stretched, and therefore, slippage and misalignment of the sanitary material when worn can be effectively prevented.

As a stretchable member of a stretchable laminate provided in a sanitary material, a stretchable film containing a thermoplastic elastomer has been proposed (for example, see patent document 1). Patent document 1 discloses a stretchable membrane containing a thermoplastic elastomer and a hydrophilic resin. The stretchable film is excellent in moisture permeability and flexibility, and is suitable for sanitary materials such as sanitary goods.

As a stretchable material that can be used in a hot-melt adhesive application device, a hot-melt stretchable adhesive composition has been proposed (see, for example, patent document 2). Patent document 2 discloses a hot-melt elastic adhesive composition containing a block copolymer including an elastic polymer segment and a polystyrene polymer segment, the elastic polymer segment being 1 or more polymers selected from hydrogenated polymers of butadiene polymers or isoprene polymers or ethylene propylene polymers. The hot-melt elastic adhesive composition can be applied using a conventional hot-melt adhesive machine, and can provide a hot-melt adhesive which can easily form a wrinkle portion by laminating the hot-melt elastic adhesive composition with a substrate such as a nonwoven fabric because the hot-melt elastic adhesive composition itself has both adhesiveness and elasticity.

Disclosure of Invention

Problems to be solved by the invention

However, when the rubber thread is used as a stretchable member used for a stretchable laminate, the body of a person is pressed by the thread, which causes a feeling of pressure and swelling when worn. Further, since the sanitary material uses a plurality of thin rubber threads, the rubber threads are easily broken during the production of the sanitary material, and there is a problem that the production of the sanitary material is often difficult.

The stretchable film of patent document 1 can solve the above-mentioned problems in the case of using a rubber thread, but in the production, the composition used for producing the stretchable film has a high viscosity, and therefore, an extrusion device is required, and a hot-melt adhesive application device which is generally used cannot be used, and there is a problem that the production efficiency of sanitary materials is poor. Further, the stretchable film of patent document 1 has a problem that heat aging occurs when the composition is heated during production because the heat stability is not sufficiently studied.

Further, the hot-melt stretchable adhesive composition of patent document 2 has a problem that a sanitary material having a stretchable laminate using the stretchable adhesive composition may slip and shift when worn because of low stress during stretching. There is also a problem that the elastic recovery after elongation is insufficient when the elastic adhesive composition is used as an elastic member.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a stretchable hot melt composition which is excellent in extensibility and stretch recovery after extension, exhibits a suitable stress when extended, is excellent in heat stability, and can be applied by a hot melt adhesive application device which is generally used.

Means for solving the problems

The present inventors have conducted extensive studies to achieve the above object, and as a result, have found that the above object can be achieved by a stretchable hot melt composition containing a thermoplastic elastomer (a) and a plasticizer (B), the thermoplastic elastomer (a) containing a hydrogenated product of a styrene-based block copolymer, and the thermoplastic elastomer (a) and the plasticizer (B) in contents within a specific range, and having a melt viscosity at 180 ℃ of 40,000mPa · s or less, and have completed the present invention.

Namely, the present invention relates to the following stretchable hot melt composition.

1. A stretchable hot melt composition comprising a thermoplastic elastomer (A) and a plasticizer (B), wherein the thermoplastic elastomer (A) contains a hydrogenated product of a styrene-based block copolymer, the stretchable hot melt composition contains 45 to 75 mass% of the thermoplastic elastomer (A) and 5 to 40 mass% of the plasticizer (B) in 100 mass%, and the stretchable hot melt composition has a melt viscosity of 40000 mPas or less at 180 ℃.

2. The stretchable hot-melt composition according to item 1, wherein the thermoplastic elastomer (A) comprises a styrene-ethylene/butylene/styrene-styrene copolymer.

3. The stretchable hot melt composition according to item 1 or 2, further comprising 5 to 35% by mass of a wax (C) having at least 1 group selected from a carbonyl group, a carboxyl group and a carboxylic anhydride group in a molecule.

4. The stretchable hot melt composition according to any one of claims 1 to 3, wherein the tan is 1.5 or less at a temperature at which a loss tangent tan (loss modulus G '/storage modulus G') measured at a frequency of 1Hz during temperature increase reaches a maximum value in a dynamic viscoelasticity measurement at-60 ℃ to-20 ℃.

5. A stretchable laminate comprising a nonwoven fabric bonded to at least one surface of the stretchable hot melt composition according to any one of claims 1 to 4.

Effects of the invention

The stretchable hot melt composition of the present invention is excellent in extensibility and stretch recovery after elongation, exhibits a suitable stress at the time of elongation, is excellent in heat stability, and can be applied by a hot melt adhesive application device that is generally used.

Detailed Description

1. Stretchable hot melt composition

The stretchable hot melt composition comprises a thermoplastic elastomer (A) containing a hydrogenated product of a styrene block copolymer and a plasticizer (B), wherein the stretchable hot melt composition comprises, by mass, 45-75% of the thermoplastic elastomer (A) and 5-40% of the plasticizer (B) per 100%, and has a melt viscosity of 40,000 mPas or less at 180 ℃. The stretchable hot melt composition of the present invention has the above-mentioned features, and therefore, has excellent elongation and stretch recovery after elongation, exhibits a suitable stress when stretched, has excellent heat stability, and can be applied by a hot melt adhesive application device that is generally used.

The stretchable hot melt composition of the present invention is suitably used as a member for a stretchable laminate to be provided in sanitary materials and the like. In general, as a member used for a stretchable laminate, a rubber thread formed by threading a natural rubber or a synthetic polymer is known. The stretchable member used for the wrinkle portion of the conventional sanitary material is formed by joining a base material such as a nonwoven fabric to a plurality of rubber threads. The stretchable member thus formed has good stretchability, and therefore, when it is used in an absorbent article, it is less likely to be displaced when worn, and the wearer is relieved. However, in the stretchable laminate formed as described above, the periphery of the waist of the wearer is subjected to a linear pressure by the linear rubber thread, and therefore, a strong tightening feeling may be felt.

By using the stretchable member using the stretchable film for stretching the periphery of the waist portion by the face pressure, the pressure applied to the wearer can be dispersed, and thus a good stretching feeling can be achieved. However, since the stretchable film has a high viscosity and is not of a hot-melt type, it cannot be coated by a hot-melt coating apparatus which is generally used, and the production process of the sanitary material becomes complicated.

By using the hot-melt stretchable adhesive composition as the stretchable member, a stretchable laminate which is tightened with a surface pressure can be produced using a general hot-melt coating apparatus. However, in the conventional hot-melt elastic adhesive composition, since the stress at the time of elongation is low, a sufficient tightening feeling is not obtained at the time of wearing, and the sanitary material may be displaced by sliding.

On the other hand, if the stretchable hot-melt composition of the present invention is used for a stretchable member of a stretchable laminate of a sanitary material, since the coating can be performed by a hot-melt coating apparatus which is generally used, the production process of the sanitary material is not complicated, and the stress during stretching is also high, the sanitary material having the stretchable laminate using the stretchable hot-melt composition as a stretchable member can suppress slip displacement during wearing, and can be relieved to the wearer.

The stretchable hot melt composition of the present invention will be described in detail below.

(thermoplastic elastomer (A))

The thermoplastic elastomer (a) contains a hydrogenated product of a styrenic block copolymer. Hydrogenated styrenic block copolymers refer to: a block copolymer obtained by block-copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene compound, wherein all or part of segments based on the conjugated diene compound in the block copolymer is hydrogenated.

The ethylene aromatic hydrocarbon is an aromatic hydrocarbon compound having a vinyl group. Specific examples of the vinyl aromatic hydrocarbon include styrene, o-methylstyrene, p-tert-butylstyrene, 1, 3-dimethylstyrene, α -methylstyrene, vinylnaphthalene, and vinylanthracene, and among these, styrene is preferable. The ethylene aromatic hydrocarbon may be used alone or in combination of two or more.

The conjugated diene compound is a diene compound having at least one pair of conjugated double bonds. Specific examples of the conjugated diene compound include 1, 3-butadiene, 2-methyl-1, 3-butadiene (or isoprene), 2, 3-dimethyl-1, 3-butadiene, 1, 3-pentadiene, 1, 3-hexadiene, etc., and among these, 1, 3-butadiene and 2-methyl-1, 3-butadiene are preferable. The conjugated diene compound may be used alone or in combination of two or more.

In the present specification, the proportion of hydrogenation in a hydrogenated thermoplastic block copolymer such as a hydrogenated product of a styrenic block copolymer is represented by "hydrogenation ratio". The "hydrogenation ratio" of the hydrogenated thermoplastic block copolymer means: a proportion of the ethylenically unsaturated double bonds hydrogenated and converted into saturated hydrocarbon bonds, based on all the ethylenically unsaturated double bonds contained in the segment based on the conjugated diene compound. The hydrogenation rate can be measured by an infrared spectrophotometer, a nuclear magnetic resonance device, or the like.

The hydrogenated product of the above-mentioned styrenic block copolymer is preferably completely hydrogenated. The hydrogenation product of the styrenic block copolymer is a complete hydrogenation product, and the heat stability of the elastic hot melt composition is further improved. The hydrogenation ratio of the hydrogenated product of the styrenic block copolymer is preferably about 100%.

The hydrogenated product of the styrenic block copolymer is not particularly limited, and may contain at least 1 selected from the group consisting of a styrene-ethylene-butylene-styrene copolymer (SEBS), a styrene-butylene-butadiene-styrene copolymer (SBBS), a styrene-ethylene/butylene/styrene-styrene copolymer (S-E/B/S-S), a styrene-ethylene-propylene-styrene copolymer (SEPS), a styrene-ethylene-propylene-styrene copolymer (SEEPS), and a styrene-ethylene-butylene-olefin crystalline copolymer (SEBC). By having the above-mentioned configuration for the thermoplastic elastomer (a), the stretchable hot-melt composition of the present invention exhibits better extensibility, excellent stretch recovery after elongation, appropriate stress at the time of elongation, and excellent heat stability. Among these, from the viewpoint of further excellent stretch recovery after elongation and the capability of satisfying both the stress at elongation and good elongation, it is preferable to contain any of a styrene-ethylene-butylene-styrene copolymer and a styrene-ethylene/butylene/styrene-styrene copolymer.

The styrene-ethylene-butylene-styrene copolymer is a copolymer in which a terminal styrene unit is an end block and an ethylene-butylene unit is a middle block. By using a copolymer in which the middle block is hydrogenated ethylene-butene units, the difference in polarity with the terminal block styrene units becomes more pronounced and the terminal block styrene units become more robust than the unhydrogenated middle block copolymer. As a result, the stress of the stretchable hot melt composition at the time of elongation can be further increased. Further, since the central block phase is hydrogenated, a more excellent stretchable hot melt composition excellent in heat stability can be provided.

The styrene content in the styrene-ethylene-butylene-styrene copolymer is preferably 15 to 45 mass%, more preferably 20 to 40 mass%, based on 100 mass% of the styrene-ethylene-butylene-styrene copolymer. When the lower limit of the styrene content is within the above range, the stretch recovery property after elongation of the stretchable hot melt composition is further improved. When the upper limit of the styrene content is within the above range, the stretchable hot melt composition becomes softer and can exhibit better extensibility.

In the present specification, the "styrene content" of a styrenic block copolymer refers to the content ratio (mass%) of a styrene block in the styrenic block copolymer.

The method for calculating the styrene content in the styrenic block copolymer in the present specification is not particularly limited, and examples thereof include a method using a proton nuclear magnetic resonance method or an infrared spectroscopy method according to JIS K6239.

As the styrene-ethylene-butylene-styrene copolymer, a commercially available product can be used. Examples of commercially available products include G1650 manufactured by Koteng Polymer Co., Ltd, MD1648 manufactured by Koteng Polymer Co., Ltd, and TUFTEC H1041 manufactured by Asahi Kasei corporation.

The styrene-ethylene-butylene-styrene copolymer may be used alone in 1 kind, or may be used in combination of 2 or more kinds. For example, a styrene-ethylene-butylene-styrene copolymer having a high styrene content may be used in combination with a styrene-ethylene-butylene-styrene copolymer having a low styrene content. In the case of using 2 or more kinds of styrene-ethylene-butylene-styrene copolymers in combination, the styrene content in the whole styrene-ethylene-butylene-styrene copolymer can be calculated from an average value based on weight.

The styrene-ethylene/butylene/styrene-styrene copolymer is a styrene-ethylene-butylene-styrene copolymer in which a terminal styrene unit is an end block and an ethylene-butylene unit is a middle block, and styrene is dispersed in the middle block. By using the copolymer in which styrene is dispersed in the mid-block phase, even if the styrene content in the entire styrene block copolymer is increased, the styrene block copolymer is not excessively hard and can exhibit good elongation, and therefore, in the stretchable hot melt composition containing the styrene-ethylene/butylene/styrene-styrene copolymer, good elongation and improvement of stress at the time of stretching can be achieved at the same time. Further, by using a styrene-ethylene/butylene/styrene-styrene copolymer in which styrene is dispersed in a mid-block phase, the increase in melt viscosity at low temperatures can be suppressed, and therefore, the coatability of the stretchable hot melt composition can be further improved.

The method for producing the styrene-ethylene/butylene/styrene-styrene copolymer is not particularly limited, and examples thereof include the method described in U.S. Pat. No. 7,169,848.

The styrene content of the styrene-ethylene/butylene/styrene-styrene copolymer is preferably 20 to 60% by mass, more preferably 25 to 55% by mass, based on 100% by mass of the styrene-ethylene/butylene/styrene-styrene copolymer. When the lower limit of the styrene content is within the above range, the stretch recovery property after elongation of the stretchable hot melt composition is further improved. When the upper limit of the styrene content is within the above range, the stretchable hot melt composition becomes softer and can exhibit better extensibility.

As the styrene-ethylene/butylene/styrene-styrene copolymer, a commercially available product can be used. Examples of commercially available products include MD6951 available from kraton polymer, a1536 available from kraton polymer, and the like.

The styrene-ethylene/butylene/styrene-styrene copolymer may be used alone in 1 kind, or may be used in combination of 2 or more kinds. For example, a styrene-ethylene/butylene/styrene-styrene copolymer having a high styrene content and a styrene-ethylene/butylene/styrene-styrene copolymer having a low styrene content may be used in combination. When 2 or more kinds are mixed and used, the styrene content in the entire styrene-ethylene/butylene/styrene-styrene copolymer can be calculated from an average value by weight.

The content of the thermoplastic elastomer (a) in the stretchable hot melt composition of the present invention is 45 to 75% by mass based on 100% by mass of the stretchable hot melt composition. When the content of the thermoplastic elastomer (a) is outside the above range, the stretchability, the recovery from stretching after stretching, and the stress at the time of stretching of the stretchable hot melt composition of the present invention are insufficient. The content of the thermoplastic elastomer (A) is preferably 50 to 70% by mass, more preferably 55 to 65% by mass.

The styrene content of the thermoplastic elastomer (a) in the stretchable hot melt composition of the present invention is preferably 10 to 35% by mass, more preferably 12 to 25% by mass, based on 100% by mass of the thermoplastic elastomer (a). When the lower limit of the styrene content is within the above range, the stretch recovery property after elongation of the stretchable hot melt composition is further improved. When the upper limit of the styrene content is within the above range, the stretchable hot melt composition becomes softer and can exhibit better extensibility.

The weight average molecular weight (Mw) of the thermoplastic elastomer (A) in the stretchable hot melt composition of the present invention is preferably 30,000 to 200,000, more preferably 40,000 to 150,000, and still more preferably 45,000 to 125,000. When the weight average molecular weight is 30,000 or more, the stretch recovery property after elongation of the stretchable hot melt composition is further improved. When the weight average molecular weight is 200,000 or less, the stretchable hot melt composition becomes softer and can exhibit better extensibility.

The weight average molecular weight (Mw) of the thermoplastic elastomer is a measurement value obtained by conversion to standard polystyrene using a gel permeation chromatography measurement apparatus.

The weight average molecular weight (Mw) in the present invention can be measured, for example, by the following measurement apparatus and measurement conditions.

A measuring device: product name "ACQUITY APC" manufactured by Waters corporation "

The measurement conditions were as follows: column

ACQUITY APCXT 451.7 μm × 1 root

ACQUITY APCXT 1252.5 μm × 1 root

ACQUITY APCXT 4502.5 μm × 1 root

Mobile phase: tetrahydrofuran 0.8 mL/min

Sample concentration: 0.2% by mass

A detector: differential Refractive Index (RI) detector

Standard substance: polystyrene (molecular weight: 266 ~ 1,800,000 produced by Waters Co.)

Column temperature: 40 deg.C

RI detector temperature: 40 deg.C

(plasticizer (B))

The stretchable hot melt composition of the present invention contains a plasticizer (B). The plasticizer (B) is preferably liquid at 23 ℃. In the present specification, the term "liquid" refers to a state in which fluidity is exhibited. The pour point of the plasticizer (B) is preferably 23 ℃ or lower, more preferably 10 ℃ or lower.

In the present specification, the pour point is a value measured by a measuring method according to JIS K2269.

The plasticizer (B) is not particularly limited, and examples thereof include paraffinic process oil, naphthenic process oil, aromatic process oil, liquid paraffin, hydrocarbon synthetic oil, and the like. Among these, paraffin-based process oils, naphthene-based process oils, liquid paraffins, and hydrocarbon-based synthetic oils are preferred from the viewpoint of excellent heat stability, and hydrocarbon-based synthetic oils are more preferred from the viewpoint of more excellent recovery from stretching after elongation.

Commercially available processing oils can be used. Examples of commercially available products include PW-32 produced by Yoghingshi, PS-32 produced by Yoghingshi, and the like.

Commercially available naphthenic process oils can be used. Examples of commercially available products include DIANA FRESIA N28 manufactured by shinxingho corporation, DIANA FRESIA U46 manufactured by shinxingho corporation, Nyflex222B manufactured by Nynas corporation, and the like.

As the liquid paraffin, commercially available products can be used. Examples of commercially available products include P-100 produced by MORESCO, Kaydol produced by Sonneborn, and the like.

As the hydrocarbon-based synthetic oil, commercially available products can be used. Examples of commercially available products include LUCANT HC-10 produced by Mitsui chemical corporation and LUCANT HC-40 produced by Mitsui chemical corporation.

The plasticizer may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the plasticizer (B) in the stretchable hot melt composition of the present invention is 5 to 40% by mass based on 100% by mass of the stretchable hot melt composition. When the content of the plasticizer (B) is less than 5% by mass, the melt viscosity of the stretchable hot melt composition increases, and the coating suitability of the stretchable hot melt composition is insufficient. When the content of the plasticizer (B) exceeds 40% by mass, the stretchable hot melt composition becomes too soft, and the stress at 2-fold elongation is reduced. The content of the plasticizer (B) is preferably 10 to 35% by mass, more preferably 12 to 30% by mass.

(wax (C))

The stretchable hot-melt composition of the present invention may contain a wax (C) having at least 1 kind of group selected from a carbonyl group, a carboxyl group and a carboxylic anhydride group in the molecule. The wax (C) is preferably solid at 23 ℃. In the present specification, "solid" means a state that does not exhibit fluidity. The softening point of the wax (C) is preferably 23 ℃ or higher, more preferably 30 ℃ or higher, and still more preferably 40 ℃ or higher.

In the present specification, the softening point is a value measured by a measurement method according to ASTM D-3954.

Since the wax having at least 1 kind of group selected from a carbonyl group, a carboxyl group and a carboxylic anhydride group in the molecule has high polarity, it has good compatibility with the styrene-based block copolymer and is well dispersed in the composition. Therefore, the heat stability of the stretchable hot melt composition can be further improved as compared with a wax having no carbonyl group, carboxyl group or carboxylic anhydride group in the molecule. The wax (C) having at least 1 kind of group selected from a carbonyl group, a carboxyl group and a carboxylic anhydride group in the molecule is not particularly limited, and examples thereof include a vinyl acetate wax, an acrylic wax, a maleic anhydride-modified wax and the like. Among them, vinyl acetate wax is preferable from the viewpoint of more excellent heat stability.

As the vinyl acetate wax, a commercially available one can be used. Examples of commercially available products include AC-400 manufactured by Honeywell, AC-430 manufactured by Honeywell, and the like.

As the acrylic wax, a commercially available product can be used. Examples of commercially available products include AC-540 manufactured by Honeywell, AC-580 manufactured by Honeywell, and the like.

As the maleic anhydride-modified wax, commercially available products can be used. Examples of commercially available products include AC-577P, manufactured by Honeywell corporation, AC-573P, Honeywell, MAW-0300, manufactured by Nippon wax Co.

The above-mentioned wax having at least 1 kind of group selected from a carbonyl group, a carboxyl group and a carboxylic anhydride group in the molecule may be used alone in 1 kind, or 2 or more kinds may be mixed and used.

The content of the wax (C) in the stretchable hot melt composition of the present invention is preferably 5 to 40% by mass, more preferably 5 to 35% by mass, and still more preferably 10 to 30% by mass, based on 100% by mass of the stretchable hot melt composition. When the lower limit of the content of the wax (C) is within the above range, the stress at 2-fold elongation of the stretchable hot melt composition is further increased. When the upper limit of the content of the wax (C) is within the above range, the permanent set of the stretchable hot melt composition is further increased.

(other additives)

The stretchable hot melt composition of the present invention may contain other additives within a range that does not substantially interfere with the object of the present invention. Examples of the other additives include antioxidants, ultraviolet absorbers, tackifier resins, liquid rubbers, and particulate fillers.

As the antioxidant, there may be mentioned: 2, 6-di-tert-butyl-4-methylphenol, n-octadecyl-3- (4' -hydroxy-3 ',5' -di-tert-butylphenyl) propionate, 2' -methylenebis (4-methyl-6-tert-butylphenol), 2' -methylenebis (4-ethyl-6-tert-butylphenol), 2, 4-bis (octylthiomethyl) o-cresol, hindered phenol antioxidants such as 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2, 4-di-tert-pentyl-6- [ 1- (3, 5-di-tert-pentyl-2-hydroxyphenyl) ethyl ] phenyl acrylate, 2- [ 1- (2-hydroxy-3, 5-di-tert-pentylphenyl) ] acrylate, and tetrakis [ methylene-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] methane; sulfur-based antioxidants such as dilauryl thiodipropionate, lauryl stearyl thiodipropionate, and pentaerythritol tetrakis (3-laurylthiopropionate); phosphorus antioxidants such as tris (nonylphenyl) phosphite and tris (2, 4-di-t-butylphenyl) phosphite. The antioxidant may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the antioxidant in the stretchable hot melt composition of the present invention is preferably 0.01 to 2% by mass, more preferably 0.05 to 1.5% by mass, and still more preferably 0.1 to 1% by mass, based on 100% by mass of the stretchable hot melt composition. When the content of the antioxidant is 0.01% by mass or more, the thermal stability of the stretchable hot melt composition is further improved. When the content of the antioxidant is 2% by mass or less, the odor of the stretchable hot melt composition is reduced.

Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers such as 2- (2 '-hydroxy-5' -methylphenyl) benzotriazole, 2- (2 '-hydroxy-3', 5 '-tert-butylphenyl) benzotriazole, and 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) -5-chlorobenzotriazole; benzophenone-based ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone; salicylate-based ultraviolet absorbers; cyanoacrylate-based ultraviolet absorbers; hindered amine light stabilizers. The ultraviolet absorber may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the ultraviolet absorber in the stretchable hot melt composition of the present invention is preferably 0.01 to 2% by mass, more preferably 0.05 to 1.5% by mass, and still more preferably 0.1 to 1% by mass, based on 100% by mass of the stretchable hot melt composition. When the content of the ultraviolet absorber is 0.01% by mass or more, the weather resistance of the stretchable hot melt composition is improved. When the content of the ultraviolet absorber is 2% by mass or less, the odor of the stretchable hot melt composition is reduced.

Examples of the tackifier resin include natural rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, copolymer of natural terpene, three-dimensional polymer of natural terpene, hydrogenated derivative of copolymer of natural terpene, terpene resin, and hydrogenated derivative of phenol-based modified terpene resin; petroleum resins such as C5-based petroleum resins, C9-based petroleum resins, C5C 9-based petroleum resins, and dicyclopentadiene-based petroleum resins, and partially hydrogenated petroleum resins and fully hydrogenated petroleum resins obtained by hydrogenating these petroleum resins. As the tackifier resin, from the viewpoint of excellent odor and thermal stability of the stretchable hot melt composition, a petroleum resin, a partially hydrogenated petroleum resin and a fully hydrogenated petroleum resin are preferable, and a partially hydrogenated petroleum resin and a fully hydrogenated petroleum resin are more preferable. These tackifying resins may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The ring and ball softening point temperature of the tackifier resin is preferably 80 ℃ or higher, and more preferably 90 ℃ or higher, from the viewpoint of further improving the stretchability and thermal stability of the stretchable hot melt composition. Further, the ring-and-ball softening point temperature of the tackifier resin is preferably 125 ℃ or lower, more preferably 120 ℃ or lower, from the viewpoint of providing the stretchable hot melt composition with better flexibility and further suppressing embrittlement. In the present specification, the ring and ball softening point temperature of the tackifier resin is a value measured in accordance with JIS K2207.

The content of the tackifier resin in the stretchable hot melt composition of the present invention is preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less, based on 100% by mass of the stretchable hot melt composition. When the content of the tackifier resin is 30% by mass or less, the stretchable hot melt composition does not become excessively hard, and the stretch recovery after stretching is further improved.

As the liquid rubber, liquid polybutene, liquid polybutadiene, liquid polyisoprene and hydrogenated resins thereof can be cited. The liquid rubber may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the liquid rubber in the stretchable hot melt composition of the present invention is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and still more preferably 3 to 10% by mass, based on 100% by mass of the stretchable hot melt composition. When the content of the liquid rubber is 1% by mass or more, the melt viscosity of the stretchable hot melt composition decreases, and the coating suitability is further improved. When the content of the liquid rubber is 20% by mass or less, the stretchable hot-melt composition does not become too soft, and the stress at 2-fold elongation is further increased.

The fine particle filler is not particularly limited, and examples thereof include calcium carbonate, kaolin, talc, titanium oxide, mica, and styrene beads. The fine particle filler may be used alone in 1 kind, or may be used in combination with 2 or more kinds.

The melt viscosity at 180 ℃ of the stretchable hot melt composition of the present invention is 40,000 mPas or less. When the melt viscosity exceeds 40,000 mPas, the coating suitability of the stretchable hot-melt composition is insufficient. The melt viscosity at 180 ℃ of the stretchable hot melt composition is preferably 28,000 mPas or less, more preferably 22,000 mPas or less. The lower limit of the melt viscosity at 180 ℃ of the stretchable hot melt composition is not particularly limited, and may be about 5,000 mPas.

In the present specification, the "melt viscosity" refers to the viscosity of a hot melt adhesive that is in a heated and melted state at a certain temperature. The method for measuring the melt viscosity at 180 ℃ includes, for example, a method in which the stretchable hot melt composition is heated and melted, and the viscosity in a molten state at 180 ℃ is measured using a Brookfield RVT type viscometer (No.29 spindle).

The stretchable hot melt composition of the present invention preferably has a tan value of 1.5 or less, more preferably 1.3 or less, and still more preferably 1.1 or less at a temperature at which the loss tangent tan (loss modulus G '/storage modulus G') reaches its maximum value as measured at a frequency of 1Hz during temperature increase at-60 ℃ to-20 ℃ by dynamic viscoelasticity measurement. When the value of tan is 1.5 or less, the adhesiveness of the stretchable hot melt composition is reduced due to the property of lowering the tackiness thereof and the stretchable hot melt composition becomes hard, and the stress at 2-fold elongation of the stretchable hot melt composition is further increased. The lower limit of tan is not particularly limited, and may be about 0.2.

In the dynamic viscoelasticity measurement, the frequency is fixed at 1Hz, and the measurement is performed in a rotational shear mode. Specifically, the dynamic viscoelasticity was measured by the following method. That is, the stretchable hot-melt composition was heated and melted at 180 ℃ and then poured onto a PET film subjected to a mold release treatment. Next, another PET film subjected to the mold release treatment was superimposed on the stretchable hot melt composition so that the release surface was in contact with the stretchable hot melt composition. Then, the composition is compressed by a hot press heated to 120 ℃ to adjust the thickness of the stretchable hot-melt composition to about 1 to 2 mm. The stretchable hot melt composition was allowed to stand at 23 ℃ for 24 hours with the release film interposed therebetween, and then the release film was removed to prepare a sample for dynamic viscoelasticity measurement. For this sample, the dynamic viscoelasticity was measured by using a dynamic viscoelasticity measuring apparatus, and raising the temperature from-80 to 130 ℃ in a rotational shear mode at a frequency of 1Hz and at a rate of 5 ℃ per minute (temperature raising process). From the measured storage modulus G 'and loss modulus G', the loss tangent tan (loss modulus G '/storage modulus G') was calculated. The value of tan at the temperature at which tan reaches a maximum value from-60 ℃ to-20 ℃ is recorded as tan maximum value. Examples of the dynamic viscoelasticity measuring apparatus include a rotational rheometer (trade name "AR-G2") manufactured by TA instruments.

The stretchable hot melt composition of the present invention preferably has a temperature at which the loss tangent tan (loss modulus G ″/storage modulus G') reaches a maximum value between-60 ℃ and-20 ℃ when measured in a temperature rise process at a frequency of 1Hz and a temperature rise rate of 5 ℃/min from-80 ℃ to 130 ℃ in a dynamic viscoelasticity measurement. By raising the temperature of the stretchable hot melt composition from-80 ℃, the composition is changed from a glass state to a rubber state with an increase in molecular motion. At this time, the value of tan had a maximum value, and the temperature at this time was evaluated as the glass transition temperature.

The stretchability of the stretchable hot melt composition of the present invention is preferably 350% or more, more preferably 450% or more, and still more preferably 550% or more. When the stretchability of the stretchable hot melt composition is 350% or more, the stretchable hot melt composition can be inhibited from breaking when stretched when wearing a sanitary material. In addition, when the stretchable hot-melt composition is stretched to produce a stretchable laminate, the elongation can be changed to an appropriate value while preventing the stretchable hot-melt composition from breaking.

The extensibility of the stretchable hot melt composition of the present invention can be measured by the following measurement method after preparing a coated sample of the stretchable hot melt composition by the following method.

(method of preparing coated sample of stretchable Hot melt composition)

The stretchable hot melt composition was coated on the release-treated PET film by slit coating at a coating temperature of 180 ℃. The coating weight was 50g/m²The coating width was set to 100 mm. Next, another PET film subjected to the mold release treatment was laminated and pressure-bonded at room temperature to prepare a laminate. The obtained laminate was stored at 23 ℃ under an atmosphere of 50% relative humidity for 24 hours, and the stretchable hot-melt composition was cooled to room temperature to prepare a coated sample of the stretchable hot-melt composition.

(method of measuring elongation)

Test pieces were prepared by cutting a coated sample of the stretchable hot melt composition into a rectangular shape having a width of 50mm with respect to the coating direction and a width of 100mm in the direction perpendicular to the coating direction. Subsequently, the PET films subjected to the mold release treatment on both surfaces were peeled off, and the test piece was fixed by a jig to a tensile tester having a jig width set to 50mm so that the direction perpendicular to the coating direction of the stretchable hot melt composition was in the vertical direction, and was stretched at a stretching speed of 500 mm/min to a point at which the test piece was broken. The displacement of the test piece at break was taken as the elongation at break (%) and as the criterion for evaluating the elongation of the stretchable hot melt composition.

Telescoping of the inventionThe stress at 2 times elongation of the hot melt composition is preferably 2.0 × 10^－4N/mm²Above, more preferably 3.2 × 10^－4N/mm²Above, more preferably 4.0 × 10^－4N/mm²The 2-fold elongation stress of the stretchable hot-melt composition was 2.0 × 10^－4N/mm²With the above, the slip dislocation at the time of wearing the sanitary material can be further suppressed.

The stress at 2 times elongation of the stretchable hot melt composition of the present invention may be less than 2.0 × 10^－4N/mm²A stress at 2 elongation of the stretchable hot melt composition of less than 2.0 × 10^－4N/mm²In this case, the stress at 2 times elongation of the stretchable hot melt composition is preferably 2.0 × 10^－4N/mm²Hereinafter, more preferably 1.8 × 10^－4N/mm²Hereinafter, more preferably 1.5 × 10^－4N/mm²The lower limit of the stress at 2-fold elongation of the stretchable hot melt composition in this case is not particularly limited, and may be 0.1 × 10^－4N/mm²Left and right.

The stress at 2-fold elongation of the stretchable hot melt composition of the present invention was measured by the following measurement method using the coated sample of the stretchable hot melt composition.

(method of measuring stress at 2-fold elongation)

Test pieces were prepared by cutting a coated sample of the stretchable hot melt composition into a rectangular shape having a width of 50mm with respect to the coating direction and a width of 100mm in the direction perpendicular to the coating direction. Subsequently, the PET films subjected to the mold release treatment on both surfaces were peeled off, and the test piece was fixed by a jig to a tensile tester having a jig width set to 50mm so that the direction perpendicular to the coating direction of the stretchable hot melt composition was positioned in the vertical direction, and was stretched at a stretching speed of 500 mm/min to a point where the strain displacement of the test piece reached 300%. Then, the substrate was returned to the original position at a speed of 500 mm/min. The procedure of stretching to the point where the strain displacement reached 300% and then returning to the initial position was regarded as 1 cycle, and 2 cycles were repeated for the same test piece.The stress value at the point where the strain displacement reached 100% at the time of stretching in the 1 st cycle was recorded as the stress at 2 times elongation (N/mm)²)。

The permanent strain of the stretchable hot melt composition of the present invention is preferably 55% or more, more preferably 70% or more, and still more preferably 80% or more. When the permanent strain of the stretchable hot melt composition is 55% or more, the stretch recovery property after elongation of the stretchable hot melt composition becomes better.

The permanent set of the stretchable hot melt composition of the present invention can be measured by the following measurement method using the coated sample of the stretchable hot melt composition.

(method of measuring permanent Strain)

Test pieces were prepared by cutting a coated sample of the stretchable hot melt composition into a rectangular shape having a width of 50mm with respect to the coating direction and a width of 100mm in the direction perpendicular to the coating direction. Subsequently, the PET films subjected to the mold release treatment on both surfaces were peeled off, and the test piece was fixed by a jig to a tensile tester having a jig width set to 50mm so that the direction perpendicular to the coating direction of the stretchable hot melt composition was positioned in the vertical direction, and was stretched at a stretching speed of 500 mm/min to a point where the strain displacement of the test piece reached 300%. Then, the substrate was returned to the original position at a speed of 500 mm/min. The procedure of stretching to the point where the strain displacement reached 300% and then returning to the initial position was regarded as 1 cycle, and 2 cycles were repeated for the same test piece. The strain displacement (%) is taken as the horizontal axis, stress (N/mm)²) In the graph plotted on the vertical axis, the integrated value in the stretching in the 1 st cycle was S1, and the integrated value in the stretching in the 2 nd cycle was S2, and the permanent strain (%) was calculated according to the following equation.

Permanent strain (%) - (S2/S1). times.100

The stretchable hot melt composition of the present invention can be produced by a known method. For example, the thermoplastic elastomer, plasticizer, wax, various additives, and the like are charged into a double-arm type kneader heated to 150 ℃ and melt kneaded while heating.

The use of the stretchable hot melt composition is not particularly limited, and examples thereof include so-called sanitary materials such as disposable diapers, sanitary napkins, hospital gowns, and the like.

The stretchable hot melt composition of the present invention is suitably used as a stretchable film and a stretchable member of a stretchable laminate containing a stretchable member. Examples of such a stretchable laminate include a stretchable laminate in which a nonwoven fabric is bonded to at least one surface of the stretchable hot melt composition. The nonwoven fabric used for the stretchable laminate is not particularly limited, and examples thereof include spunbond nonwoven fabric, spunlace nonwoven fabric, and needle-punched nonwoven fabric.

The use of the stretchable laminate is not particularly limited, and is suitably used for so-called sanitary materials such as disposable diapers and sanitary napkins.

The stretchable hot melt composition of the present invention is applied to a porous substrate such as an extensible nonwoven fabric or paper, and is therefore suitably used as a stretch reinforcing material for the porous substrate. In this way, a stretchable laminate formed by coating the stretchable hot-melt composition on a porous substrate is also one of the stretchable laminates of the present invention.

The extensible nonwoven fabric is stretched in a certain direction to a certain extent, but is difficult to return to its original length when the stretching force is removed. The stretchable laminate formed by applying the stretchable hot-melt composition of the present invention to a porous base material such as a stretchable nonwoven fabric can function as a stretchable reinforcing material and can provide a function of restoring the original length to the stretchable laminate.

The extensible nonwoven fabric is not particularly limited, and examples thereof include a spunlace nonwoven fabric and a needle-punched nonwoven fabric. The method for applying the stretchable hot-melt composition to the porous substrate is not particularly limited, and slit coating, curtain coating, spiral coating, film coating, and the like can be mentioned. When the stretchable hot-melt composition is applied by slit coating, the stretchable hot-melt composition easily penetrates into the porous base material, and therefore the stress of the stretchable laminate is further increased. Further, when the stretchable hot-melt composition is applied by spraying, the stretchable hot-melt composition can be prevented from penetrating into the porous substrate, and the texture and air permeability can be further improved.

The amount of the stretchable hot-melt composition applied to the porous substrate is not particularly limited, but is preferably 1 to 200g/m²More preferably 5 to 150g/m²More preferably 10 to 100g/m². When the lower limit of the amount of application is within the above range, the stress and the recovery rate of expansion and contraction of the stretchable laminate are further improved. When the upper limit of the amount of application is within the above range, the texture of the stretchable laminate is further improved.