WO2018151190A1

WO2018151190A1 - Hot melt adhesive and stretchable laminate

Info

Publication number: WO2018151190A1
Application number: PCT/JP2018/005170
Authority: WO
Inventors: 悠染谷
Original assignee: 積水フーラー株式会社
Priority date: 2017-02-17
Filing date: 2018-02-15
Publication date: 2018-08-23
Also published as: JPWO2018151190A1; JP6716705B2; JP2020037695A

Abstract

Provided are: a hot melt adhesive which has excellent adhesiveness and excellent thermal stability, while being suppressed in separation from a substrate after expansion and contraction and exhibiting good recovery of stretchability after expansion, and which is excellent in terms of so-called coating adequacy and is thus able to be applied by a commonly used hot melt adhesive application device even at relatively low temperatures; and a stretchable laminate which is obtained using this hot melt adhesive. A hot melt adhesive which contains a styrene block copolymer (A), a tackifying resin (B) and a plasticizer (C), and which is characterized in that: the styrene block copolymer (A) contains at least one copolymer selected from the group consisting of a styrene-ethylene-butylene/styrene-styrene copolymer, a styrene-ethylene-propylene/styrene-styrene copolymer, an unsymmetrical styrene-isoprene-styrene copolymer and an unsymmetrical styrene-butadiene-styrene copolymer; the ratio of the melt viscosity (η1) of the hot melt adhesive at 140°C to the melt viscosity (η2) of the hot melt adhesive at 180°C, namely η1/η2 is 5 or less; and the melt viscosity (η2) at 180°C is 8,000 Pa·s or less.

Description

Hot melt adhesive and stretch laminate

The present invention is excellent in adhesiveness, suppressed from peeling from the base material after stretching, exhibits good stretch recovery after stretching, has excellent thermal stability, and is usually at a relatively low temperature. The present invention relates to a hot-melt adhesive that can be applied by a hot-melt adhesive application device and a stretchable laminate using the hot-melt adhesive.

In recent years, sanitary materials such as paper diapers and sanitary napkins have been widely used, and gather parts that are stretchable laminates composed of stretchable members are provided to prevent slipping when worn. .

A hot melt stretchable adhesive composition has been proposed as an adhesive for forming a member used in a gathered portion (see, for example, Patent Document 1). Patent Document 1 discloses a block copolymer comprising an elastic polymer segment and a polystyrene polymer segment, which are one or more polymers selected from hydrogenated polymers of butadiene polymers or isoprene polymers, or ethylene propylene polymers. A hot melt stretchable adhesive composition is disclosed. According to the hot-melt stretchable adhesive composition, it can be applied using a normal hot-melt applicator, and itself has both adhesiveness and stretchability. By laminating, a hot melt adhesive that can easily form a gathered portion is provided.

Japanese Patent No. 2919385

Generally, when a hot melt adhesive is used when manufacturing sanitary materials such as disposable diapers and sanitary napkins, it is melted in a tank heated to about 150 to 170 ° C. and heated to about 150 to 170 ° C. It is applied to the substrate in a predetermined shape with a hot melt applicator. At this time, if the operating temperature is further increased, there is a problem that the thermal stability of the hot melt adhesive is lowered, causing thermal degradation, the property is changed, and odor is generated, and the safety of the user is increased. There is a problem of lowering.

Particularly, when the hot melt stretchable adhesive composition described in Patent Document 1 is used, there is a problem that the melt viscosity becomes high and the coating suitability is poor. For this reason, when used in a hot melt applicator, the coating temperature must be higher than the normal temperature, causing thermal degradation, changing the properties of the hot melt adhesive, generating an unpleasant odor, and using it. There is a problem that the safety of the person is reduced. In addition, there is a problem that the adhesive strength of the hot-melt stretchable adhesive composition to the base material is insufficient, and the stretchability is applied to a base material such as a non-woven fabric and bonded to another base material such as a non-woven fabric. When the laminate is stretched, there is a problem that the hot-melt stretchable adhesive composition and the substrate such as the nonwoven fabric are peeled off and peeled off during stretching.

In addition, the hot melt stretchable adhesive composition described in Patent Document 1 has not been sufficiently examined for stretch recovery properties, and when used as a member for forming a sanitary material, recovery after stretching is not sufficient. There's a problem.

In view of the above circumstances, the present invention is excellent in adhesiveness, suppressed from peeling with the base material after stretching, exhibits good stretch recovery after stretching, and is also excellent in thermal stability. It is an object of the present invention to provide a hot melt adhesive excellent in coating suitability that can be applied with a hot melt adhesive application device that is normally used even at a low temperature, and a stretchable laminate using the hot melt adhesive.

As a result of intensive studies to achieve the above object, the present inventors have found a hot melt adhesive containing a styrene-based block copolymer (A), a tackifier resin (B), and a plasticizer (C). Then, a specific copolymer is used as the styrenic block copolymer (A), and the ratio (η1 / η2) of the melt viscosity (η1) at 140 ° C. to the melt viscosity (η2) at 180 ° C. is 5 or less. In addition, according to the hot melt adhesive having a melt viscosity at 180 ° C. of 8,000 mPa · s or less, the inventors have found that the above object can be achieved, and have completed the present invention.

That is, the present invention relates to the following hot melt adhesive and stretchable laminate.
1. A hot-melt adhesive containing a styrene block copolymer (A), a tackifier resin (B), and a plasticizer (C),
The styrenic block copolymer (A) includes styrene-ethylene-butylene / styrene-styrene copolymer, styrene-ethylene-propylene / styrene-styrene copolymer, asymmetric styrene-isoprene-styrene copolymer, and asymmetric Containing at least one selected from the group consisting of styrene-butadiene-styrene copolymers,
The hot melt adhesive has a ratio (η1 / η2) of a melt viscosity (η1) at 140 ° C. to a melt viscosity (η2) at 180 ° C. of 5 or less, and a melt viscosity (η2) at 180 ° C. of 8 , 000 mPa · s or less,
A hot melt adhesive characterized by that.
2. The styrenic block copolymer (A) contains at least one selected from the group consisting of a styrene-ethylene-butylene / styrene-styrene copolymer and an asymmetric styrene-isoprene-styrene copolymer. The hot melt adhesive according to 1.
3. Item 3. The hot melt adhesive according to

Item

1 or 2, wherein the content of the plasticizer (C) is 50 to 200 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A).
4). A stretchable laminate comprising a pair of base materials bonded together by the hot melt adhesive according to any one of Items 1 to 3.

The hot melt adhesive of the present invention is excellent in adhesiveness, suppressed from peeling with the base material after stretching, exhibits good stretch recovery after stretching, and has excellent thermal stability, It can be applied with a commonly used hot melt adhesive application device even at a relatively low temperature, and exhibits excellent coating suitability. Moreover, since the stretch laminate of the present invention has a pair of base materials bonded together by the hot melt adhesive, delamination after stretching is suppressed, and good stretch recovery properties after stretching are exhibited. be able to.

It is sectional drawing which shows an example of the layer structure of the elastic laminated body of this invention.

The hot melt adhesive of the present invention is a hot melt adhesive containing a styrene block copolymer (A), a tackifier resin (B), and a plasticizer (C), wherein the styrene block copolymer ( A) is a styrene-ethylene-butylene / styrene-styrene copolymer, a styrene-ethylene-propylene / styrene-styrene copolymer, an asymmetric styrene-isoprene-styrene copolymer, and an asymmetric styrene-butadiene-styrene copolymer. The hot melt adhesive contains at least one selected from the group consisting of: a melt viscosity (η1) at 140 ° C. and a melt viscosity (η2) at 180 ° C. (η1 / η2) of 5 or less. And a hot melt adhesive having a melt viscosity at 180 ° C. of 8,000 mPa · s or less. The hot melt adhesive of the present invention comprises the above (A) to (C), and in particular, the styrenic block copolymer (A) is a styrene-ethylene-butylene / styrene-styrene copolymer, styrene-ethylene-propylene. / Contains at least one selected from the group consisting of styrene-styrene copolymer, asymmetric styrene-isoprene-styrene copolymer, and asymmetric styrene-butadiene-styrene copolymer. Peeling from the substrate is suppressed, it exhibits good stretch recovery after stretching, is excellent in thermal stability, and is excellent in coating suitability.

The hot melt adhesive of the present invention can be suitably used as a member used in gathered parts such as sanitary materials. In general, as a member used for the gathered portion, thread rubber made of natural rubber or synthetic polymer in a thread form is known. The elastic member used for the gathered part of the conventional sanitary material is formed by joining a base material such as a nonwoven fabric and a plurality of thread rubbers. Since the stretchable member formed in this manner has good stretchability, when used for absorbent articles, it is difficult for the wearer to shift during wearing, giving the wearer a sense of security. However, the gathered portion formed as described above may feel a strong tightening feeling because the linear pressure due to the linear rubber thread is applied to the wearer's waist.

Since the pressure applied to the wearer is dispersed by using an elastic member using an elastic film that tightens the waistline with surface pressure, a good feeling of tightening can be achieved. However, the stretchable film has no adhesiveness, and in order to form a stretchable member including a stretchable film, it can be stretched with respect to a substrate such as a non-woven fabric by hot melt adhesive, heat fusion, ultrasonic bonding, etc. The process of joining the conductive film is indispensable, and the process becomes complicated.

On the other hand, if the base material used in the gathered part of the sanitary material is joined using the hot melt adhesive of the present invention, an adhesive layer exhibiting stretchability is formed between the base materials by the hot melt adhesive of the present invention. And since the said adhesive bond layer has adhesiveness, it is not necessary to newly provide the joining process to a base material.

Hereinafter, the hot melt adhesive and stretchable laminate of the present invention will be described in detail.

1. Hot-melt adhesive The hot-melt adhesive of the present invention is a hot-melt adhesive containing a styrenic block copolymer (A), a tackifier resin (B), and a plasticizer (C), wherein the styrenic block The copolymer (A) includes styrene-ethylene-butylene / styrene-styrene copolymer, styrene-ethylene-propylene / styrene-styrene copolymer, asymmetric styrene-isoprene-styrene copolymer, and asymmetric styrene-butadiene- It contains at least one selected from the group consisting of styrene copolymers, and the hot melt adhesive has a ratio (η1 / η2) of the melt viscosity (η1) at 140 ° C. and the melt viscosity (η2) at 180 ° C. Is 5 or less, and the melt viscosity at 180 ° C. is 8,000 mPa · s or less.

(Styrene block copolymer (A))
Styrenic block copolymers (A) are styrene-ethylene-butylene / styrene-styrene copolymer (“SEBS / S”), styrene-ethylene-propylene / styrene-styrene copolymer (“SEPS / S”). And at least one selected from the group consisting of an asymmetric styrene-isoprene-styrene copolymer (“asymmetric SIS”) and an asymmetric styrene-butadiene-styrene copolymer (“asymmetric SBS”). Since the styrenic block copolymer (A) has the above-described configuration, the hot melt adhesive of the present invention exhibits good stretchability, and is prevented from being peeled off from the stretched base material. Can show aptitude. Styrene-ethylene-butylene / styrene-styrene copolymers and asymmetric styrene-isoprene-styrene copolymers are preferred in that thermal stability can be further improved and odor can be further reduced, and styrene-ethylene- A butylene / styrene-styrene copolymer is more preferred.

The styrene-ethylene-butylene / styrene-styrene copolymer is a styrene-ethylene-butylene-styrene copolymer in which a terminal styrene unit is an end block phase and an ethylene-butylene unit is a mid block phase. Further, it is a copolymer in which styrene is dispersed. By using a copolymer in which styrene is dispersed in the midblock phase, even if the blending amount of styrene-ethylene-butylene / styrene-styrene copolymer in the hot melt adhesive is increased, it is about 140 ° C. or less. Stretch hot that has excellent coating droplet properties because it suppresses the increase in melt viscosity at low temperatures, has good stretchability, is suppressed from peeling after being stretched, and has excellent thermal stability A melt adhesive can be provided.

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

The styrene content of the styrene-ethylene-butylene / styrene-styrene copolymer is preferably 20% by mass or more, more preferably 30% by mass or more based on 100% by mass of the styrene-ethylene-butylene / styrene-styrene copolymer. When the lower limit of the styrene content of the styrene-ethylene-butylene / styrene-styrene copolymer is within the above range, the stretch recovery property after elongation of the hot melt adhesive is further improved. The styrene content of the styrene-ethylene-butylene / styrene-styrene copolymer is preferably 70% by mass or less, more preferably 60% by mass or less, based on 100% by mass of the styrene-ethylene-butylene / styrene-styrene copolymer. preferable. When the upper limit of the styrene content of the styrene-ethylene-butylene / styrene-styrene copolymer is within the above range, the hot-melt adhesive becomes softer and better adhesive strength can be expressed.

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

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

As the styrene-ethylene-butylene / styrene-styrene copolymer, commercially available products can be used. Examples of commercially available products include MD6951 manufactured by Kraton Polymer, A1536 manufactured by Kraton Polymer, and the like.

The styrene-ethylene-butylene / styrene-styrene copolymer may be used singly or in combination of two or more. 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 mixed and used. What is necessary is just to calculate the styrene content of the whole styrene-ethylene-butylene / styrene-styrene copolymer at the time of using 2 or more types mixedly by the average value based on a weight.

The styrene-ethylene-propylene / styrene-styrene copolymer is a styrene-ethylene-propylene-styrene copolymer in which a terminal styrene unit is an end block phase and an ethylene-propylene unit is a mid block phase. Further, it is a copolymer in which styrene is dispersed. By using a copolymer in which styrene is dispersed in the midblock phase, even if the blending amount of styrene-ethylene-propylene / styrene-styrene copolymer in the hot melt adhesive is increased, it is about 140 ° C. or less. Stretch hot that has excellent coating droplet properties because it suppresses the increase in melt viscosity at low temperatures, has good stretchability, is suppressed from peeling after being stretched, and has excellent thermal stability A melt adhesive can be provided.

The styrene content of the styrene-ethylene-propylene / styrene-styrene copolymer is preferably 20% by mass or more, more preferably 30% by mass or more based on 100% by mass of the styrene-ethylene-propylene / styrene-styrene copolymer. When the lower limit of the styrene content of the styrene-ethylene-propylene / styrene-styrene copolymer is within the above range, the stretch recovery property after elongation of the hot melt adhesive is further improved. The styrene content of the styrene-ethylene-propylene / styrene-styrene copolymer is preferably 70% by mass or less, more preferably 60% by mass or less, based on 100% by mass of the styrene-ethylene-propylene / styrene-styrene copolymer. preferable. When the upper limit of the styrene content of the styrene-ethylene-propylene / styrene-styrene copolymer is within the above range, the hot-melt adhesive becomes softer and better adhesive strength can be exhibited.

The styrene-ethylene-propylene / styrene-styrene copolymer may be used alone or in combination of two or more. For example, a styrene-ethylene-propylene / styrene-styrene copolymer having a high styrene content and a styrene-ethylene-propylene / styrene-styrene copolymer having a low styrene content may be mixed and used. What is necessary is just to calculate the styrene content of the whole styrene-ethylene-propylene / styrene-styrene copolymer by mixing 2 or more types by the average value based on weight.

The asymmetric styrene-isoprene-styrene copolymer is an asymmetric styrene-isoprene-styrene copolymer, and “asymmetric” refers to the content of styrene in the styrene phase at both ends of the styrene-isoprene-styrene copolymer. Means different. Using an asymmetric styrene-isoprene-styrene copolymer suppresses an increase in melt viscosity at a low temperature of about 140 ° C. or less even when the amount of the asymmetric styrene-isoprene-styrene copolymer in the hot melt adhesive increases. Therefore, it is possible to provide a stretchable hot melt adhesive that has good stretchability, is prevented from being peeled off from the stretched base material, and has excellent coating suitability.

The styrene content of the asymmetric styrene-isoprene-styrene copolymer is preferably 20% by mass or more, more preferably 30% by mass or more, based on 100% by mass of the asymmetric styrene-isoprene-styrene copolymer. When the lower limit of the styrene content of the asymmetric styrene-isoprene-styrene copolymer is within the above range, the stretch recovery property after elongation of the hot melt adhesive is further improved. The styrene content of the asymmetric styrene-isoprene-styrene copolymer is preferably 70% by mass or less, more preferably 60% by mass or less, based on 100% by mass of the asymmetric styrene-isoprene-styrene copolymer. When the upper limit of the styrene content of the asymmetric styrene-isoprene-styrene copolymer is within the above range, the hot-melt adhesive becomes softer and better adhesive strength can be expressed.

As the asymmetric styrene-isoprene-styrene copolymer used in the present invention, commercially available products can be used. For example, Nippon Zeon 3390 and the like can be mentioned.

The asymmetric styrene-isoprene-styrene copolymer may be used alone or in combination of two or more. For example, an asymmetric styrene-isoprene-styrene copolymer having a high styrene content and an asymmetric styrene-isoprene-styrene copolymer having a low styrene content may be mixed and used. What is necessary is just to calculate the styrene content of the whole asymmetric styrene-isoprene-styrene copolymer at the time of using 2 or more types mixedly by the average value based on a weight.

The asymmetric styrene-butadiene-styrene copolymer is an asymmetric styrene-butadiene-styrene copolymer, and the term “asymmetric” refers to the styrene content in the styrene phases at both ends of the styrene-butadiene-styrene copolymer. Means different. Using an asymmetric styrene-butadiene-styrene copolymer suppresses an increase in melt viscosity at a low temperature of about 140 ° C. or less even when the amount of the asymmetric styrene-butadiene-styrene copolymer in the hot melt adhesive increases. Therefore, it is possible to provide a stretchable hot melt adhesive that has good stretchability, is prevented from being peeled off from the stretched base material, and has excellent coating suitability.

The styrene content of the asymmetric styrene-butadiene-styrene copolymer is preferably 20% by mass or more, more preferably 30% by mass or more, based on 100% by mass of the asymmetric styrene-butadiene-styrene copolymer. When the lower limit of the styrene content of the asymmetric styrene-butadiene-styrene copolymer is within the above range, the stretch recovery property after elongation of the hot melt adhesive is further improved. The styrene content of the asymmetric styrene-butadiene-styrene copolymer is preferably 70% by mass or less, more preferably 60% by mass or less, based on 100% by mass of the asymmetric styrene-butadiene-styrene copolymer. When the upper limit of the styrene content of the asymmetric styrene-butadiene-styrene copolymer is within the above range, the hot-melt adhesive becomes softer and better adhesive strength can be expressed.

The asymmetric styrene-butadiene-styrene copolymer may be used alone or in combination of two or more. For example, an asymmetric styrene-butadiene-styrene copolymer having a high styrene content and an asymmetric styrene-butadiene-styrene copolymer having a low styrene content may be mixed and used. What is necessary is just to calculate the styrene content of the whole asymmetric styrene-butadiene-styrene copolymer in the case of using 2 or more types mixedly by the average value based on weight.

The styrene block copolymer (A) includes the styrene-ethylene-butylene / styrene-styrene copolymer, styrene-ethylene-propylene / styrene-styrene copolymer, asymmetric styrene-isoprene-styrene copolymer, and asymmetric A styrene block copolymer other than the styrene-butadiene-styrene copolymer may be contained. Other styrene block copolymers include styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), styrene-butadiene / butylene-styrene copolymer (SBBS), and styrene. -Ethylene-butylene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), and the like.

Commercially available products can be used as the other styrenic block copolymers. Commercially available products include, for example, ZEON Corporation Quintac 3433 (SIS), Asahi Kasei Corporation Tuftec P1500 (SBBS), Asahi Kasei Corporation Tuftec H1041 (SEBS), Kuraray Septon 2002 (SEPS), and the like.

The content of the other styrene block copolymer in the styrene block copolymer (A) is preferably 1% by mass or more, preferably 10% by mass or more, based on 100% by mass of the styrene block copolymer (A). Is more preferable. The content of the other styrene block copolymer in the styrene block copolymer (A) is preferably 50% by mass or less, based on 100% by mass of the styrene block copolymer (A), and 40% by mass. % Or less is more preferable. By setting the content of other styrenic block copolymers in the above range, the hot melt adhesive of the present invention has even better adhesion, suppression of peeling from the stretched base material, stretch after stretching. Recoverability can be exhibited, and more excellent thermal stability and coating suitability can be exhibited.

The content of the styrenic block copolymer (A) in the hot melt adhesive of the present invention is preferably 25% by mass or more, more preferably 30% by mass or more, and 35% by mass with 100% by mass of the hot melt adhesive. The above is more preferable. The content of the styrenic block copolymer (A) in the hot melt adhesive of the present invention is preferably 65% by mass or less, more preferably 60% by mass or less, based on 100% by mass of the hot melt adhesive. A mass% or less is more preferable. By setting the content of the styrenic block copolymer (A) in the hot melt adhesive of the present invention within the above range, the hot melt adhesive of the present invention has even more excellent adhesiveness and a substrate after stretching. In addition, it is possible to show the suppression of peeling and the stretch recovery property after stretching, and more excellent thermal stability and coating suitability.

The styrene content of the styrenic block copolymer (A) in the hot melt adhesive of the present invention is preferably 20% by mass or more, and more preferably 30% by mass or more, based on 100% by mass of the styrenic block copolymer (A). More preferred. When the lower limit of the styrene content of the styrenic block copolymer (A) is within the above range, the stretch recovery property after elongation of the hot melt adhesive is further improved. The styrene content of the styrene block copolymer (A) is preferably 70% by mass or less, more preferably 60% by mass or less, based on 100% by mass of the styrene block copolymer (A). When the upper limit of the styrene content of the styrenic block copolymer (A) is within the above range, the hot-melt adhesive becomes softer, and better adhesive strength can be expressed.

The weight average molecular weight (Mw) of the styrenic block copolymer (A) contained in the hot melt adhesive of the present invention is preferably 30,000 or more, more preferably 40,000 or more, and still more preferably 45,000 or more. 50,000 or more is particularly preferable. When the lower limit of the weight average molecular weight of the styrenic block copolymer (A) is in the above range, the stretch recovery property after elongation of the hot melt adhesive is further improved. The weight average molecular weight (Mw) of the styrene block copolymer (A) contained in the hot melt adhesive of the present invention is preferably 200,000 or less, more preferably 150,000 or less, and 125,000 or less. More preferred is 110,000 or less. When the upper limit of the weight average molecular weight of the styrenic block copolymer (A) is within the above range, the hot melt adhesive becomes softer and more excellent extensibility can be expressed.

The weight average molecular weight (Mw) of the styrene-based block copolymer is a measured value obtained by conversion with standard polystyrene using a gel permeation chromatography measuring device.

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

(Tackifying resin (B))
The hot melt adhesive of the present invention contains a tackifying resin (B). Tackifying resin (B) includes natural rosin, modified rosin, natural rosin glycerol ester, modified rosin glycerol ester, natural rosin pentaerythritol ester, modified rosin pentaerythritol ester, natural terpene copolymer, natural terpene tertiary Hydrogenated derivatives of original polymers, natural terpene copolymers, terpene resins, hydrogenated derivatives of phenolic modified terpene resins; petroleum resins such as C5 petroleum resins, C9 petroleum resins, C5C9 petroleum resins, dicyclopentadiene petroleum resins Also, partially hydrogenated petroleum resins obtained by adding hydrogen to these petroleum resins, fully hydrogenated petroleum resins and the like can be mentioned. The tackifying resin (B) is preferably a petroleum resin, a partially hydrogenated petroleum resin, or a fully hydrogenated petroleum resin in terms of excellent odor and thermal stability of the hot melt adhesive, and a partially hydrogenated petroleum resin, And fully hydrogenated petroleum resin is more preferred.

The above tackifying resins may be used alone or in combination of two or more.

The ring-and-ball softening point temperature of the tackifying resin is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, from the viewpoint that the stretchability and thermal stability of the hot melt adhesive are further improved. In addition, the ring and ball softening point temperature of the tackifying resin is preferably 125 ° C. or lower, more preferably 120 ° C. or lower, in that the hot-melt adhesive composition can provide more flexibility and further suppress weakening. More preferred. In the present specification, the ring and ball softening point temperature of the tackifier resin is a value measured according to JIS K2207.

The content of the tackifier resin (B) in the hot melt adhesive of the present invention is preferably 10 parts by mass or more and more preferably 15 parts by mass or more with respect to 100 parts by mass of the styrenic block copolymer (A). 20 parts by mass or more is more preferable. When the lower limit of the content of the tackifying resin (B) is within the above range, the hot melt adhesive of the present invention can exhibit even better adhesive strength. Moreover, 80 mass parts or less are preferable with respect to 100 mass parts of said styrenic block copolymers (A), and, as for content of the tackifying resin (B) in the hot-melt-adhesive of this invention, 60 mass parts or less are preferable. More preferred is 50 parts by mass or less. When the upper limit of the content of the tackifying resin (B) is within the above range, the content of the styrene block copolymer (A) is relatively increased, and the stretchability and heat of the hot melt adhesive of the present invention are increased. Stability is further improved.

Commercially available products can be used as the tackifier resin (B). Examples of commercially available products include HA-103 manufactured by TonenGeneral Sekiyu KK, Alcon M-100 manufactured by Arakawa Chemical Co., Ltd., Imabe P100 manufactured by Idemitsu Kosan Co., Ltd., and SCOLEZ SU400 manufactured by Kolon.

(Plasticizer (C))
The hot melt adhesive of the present invention contains a plasticizer (C). The plasticizer (C) is not particularly limited, and examples thereof include paraffinic process oil, naphthenic process oil, aromatic process oil, liquid paraffin, and hydrocarbon synthetic oil. Among these, paraffinic process oil, naphthenic process oil, liquid paraffin, and hydrocarbon synthetic oil are preferable, and paraffinic process oil, liquid paraffin, and hydrocarbon synthetic oil are more preferable. Paraffinic process oil is more preferable in that the coating suitability is further improved.

Commercially available products can be used as the paraffinic process oil. Examples of commercially available products include Idemitsu Kosan PW-32, Idemitsu Kosan Diana Fresia S32, Idemitsu Kosan PS-32, and the like. By using the paraffinic process oil, the increase in the melt viscosity at a low temperature of the hot melt adhesive is suppressed, and the ratio (η1 / η2) between the melt viscosity (η1) at 140 ° C. and the melt viscosity (η2) at 180 ° C. ) Can be further reduced, and coating suitability is further improved.

Commercial products can be used as naphthenic process oil. Examples of commercially available products include Diana Fresia N28 manufactured by Idemitsu Kosan Co., Ltd., Diana Fresia U46 manufactured by Idemitsu Kosan Co., and Diana Process Oil NR manufactured by Idemitsu Kosan Co., Ltd.

Commercially available products can be used as liquid paraffin. Commercially available products include P-100 manufactured by MORESCO, Kaydol manufactured by Sonneborn, and the like.

Commercial products can be used as the hydrocarbon synthetic oil. Examples of commercially available products include Lucant HC-10 manufactured by Mitsui Chemicals, Lucant HC-20 manufactured by Mitsui Chemicals, and the like. By using the hydrocarbon synthetic oil, the stretch recovery property (permanent strain) of the hot melt adhesive is further improved.

The above plasticizers may be used alone or in combination of two or more.

The content of the plasticizer (C) in the hot melt adhesive of the present invention is preferably 50 parts by mass or more, more preferably 70 parts by mass or more based on 100 parts by weight of the styrene block copolymer (A). When the lower limit of the content of the plasticizer (C) is in the above range, the melt viscosity of the hot melt adhesive is further reduced, and the coating suitability of the hot melt adhesive is further improved. Further, the content of the plasticizer (C) in the hot melt adhesive of the present invention is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, based on 100 parts by weight of the styrenic block copolymer (A). 130 mass parts or less are still more preferable, and 100 mass parts or less are especially preferable. When the upper limit of the content of the plasticizer (C) in the hot melt adhesive of the present invention is in the above range, the hot melt adhesive does not become too soft, and the stretch recovery property after extension of the hot melt adhesive is further increased. improves.

(Other additives)
The hot melt adhesive of the present invention may contain other additives as long as the object of the present invention is not essentially disturbed. Examples of the other additives include waxes, antioxidants, ultraviolet absorbers, and liquid rubber.

The wax is not particularly limited. For example, animal wax such as shellac wax and beeswax; plant wax such as carnauba wax and beeswax; mineral wax such as paraffin wax and macrocrystalline wax; Fischer-Tropsch wax, ethylene -Synthetic waxes such as polyolefin waxes including vinyl acetate copolymer (EVA) waxes. Among these, polyolefin waxes are preferable in that the deterioration of the thermal stability of the hot melt adhesive can be further suppressed, and the generation of odor can be further reduced. Waxes may be used alone or in combination of two or more.

A commercially available product can be used as the wax. Commercially available polyolefin waxes are Honeywell A-C7, INNOSPEC Viscowax 122, and ethylene-vinyl acetate copolymer (EVA) waxes are Honeywell A-C400, INNOSPEC VISCOWAX 334 may be mentioned.

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-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-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] hindered phenolic antioxidants such as methane; dilauryl thiodipropionate, lauryl stearyl thiodipropionate, pentaerythritol tetrakis (3-lauryl) Sulfur antioxidants such as thiopropionate); phosphorus antioxidants such as tris (nonylphenyl) phosphite and tris (2,4-di-t-butylphenyl) phosphite. An antioxidant may be used individually by 1 type, and 2 or more types may be mixed and used for it.

Examples of the ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl) benzotriazole, 2- (2 ′ -Hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole and other benzotriazole ultraviolet absorbers; 2-hydroxy-4-methoxybenzophenone and other benzophenone ultraviolet absorbers; salicylic acid ester Examples include ultraviolet absorbers; cyanoacrylate ultraviolet absorbers; hindered amine light stabilizers. An ultraviolet absorber may be used individually by 1 type, and 2 or more types may be mixed and used for it.

Examples of the liquid rubber include liquid polybutene, liquid polybutadiene, liquid polyisoprene, and hydrogenated resins thereof. A liquid rubber may be used individually by 1 type, and may mix and use 2 or more types.

The total content of the other additives in the hot melt adhesive of the present invention is preferably 0.1 parts by mass or more, based on 100 parts by mass of the styrenic block copolymer (A), and 0.5 parts by mass. Part or more is more preferable. Further, the total content of the other additives is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, based on 100 parts by mass of the styrene block copolymer (A). By setting the total content of the other additives in the above range, the hot melt adhesive of the present invention has even better adhesion, suppression of peeling from the stretched substrate, and stretch recovery after stretching. It is possible to show the properties, and it is possible to show a further excellent thermal stability and coating suitability, and to impart desired performance to the hot melt adhesive of the present invention.

The ratio of the melt viscosity (η1) at 140 ° C. to the melt viscosity (η2) at 180 ° C. (η1 / η2) of the hot melt adhesive of the present invention is 5 or less. If η1 / η2 exceeds 5, the melt viscosity of the hot melt adhesive increases when the coating temperature is lowered, and good coating suitability cannot be maintained. η1 / η2 is preferably 5 or less, and more preferably 4 or less. Further, the lower limit of η1 / η2 is not particularly limited, and is about 1.5.

In this specification, “melt viscosity” is the viscosity of a hot melt adhesive that has been heated and melted at a certain temperature. The ratio (η1 / η2) between the melt viscosity (η1) at 140 ° C. and the melt viscosity (η2) at 180 ° C. is a value measured by the following measurement method. That is, the hot-melt adhesive is heated and melted, and the melted viscosities at 140 ° C. and 180 ° C. are measured using a Brookfield RVT viscometer (spindle No. 29), which are η1 and η2, respectively. It is a value measured by calculating the ratio η1 / η2 of the melt viscosity at 140 ° C. and 180 ° C. based on the measurement result.

The hot melt adhesive of the present invention has a melt viscosity (η2) at 180 ° C. of 8000 mPa · s or less. When η2 exceeds 8000 mPa · s, the coating suitability of the hot melt adhesive of the present invention is lowered. η2 is preferably 7,500 mPa · s or less. Moreover, η2 is preferably 3000 mPa · s or more, and more preferably 4,000 mPa · s or more. By setting η2 within the above range, the hot melt adhesive of the present invention is further excellent in coating suitability, and the value of η1 / η2 can be easily adjusted to 5 or less.

The melt viscosity (η1) at 140 ° C. is preferably 10,000 mPa · s or more, and more preferably 13,000 mPa · s or more. Moreover, η1 is preferably 30,000 mPa · s or less, and more preferably 20,000 mPa · s or less. By setting η1 within the above range, the hot melt adhesive of the present invention is further excellent in coating suitability, and the value of η1 / η2 can be easily adjusted to 5 or less.

The stretch recovery property (permanent strain) of the hot melt adhesive of the present invention is preferably 15% or less, and more preferably 10% or less.

The stretch recovery property (permanent strain) of the hot melt adhesive of the present invention is measured by the following measuring method.

(Measurement method of stretch recovery)
The hot melt adhesive is applied to the spunlace nonwoven fabric F2650 manufactured by Suominen by slot coating at a coating temperature of 160 to 180 ° C. The coating amount is 50 g / m ² and the coating width is 100 mm. Next, a non-woven fabric F2650 is prepared separately, laminated on the non-woven fabric coated with the hot melt adhesive prepared as described above, and pressure-bonded at room temperature to prepare a laminate. At this time, the time from when the hot melt adhesive is applied to the first nonwoven fabric until the second nonwoven fabric is laminated and pressure bonded is 1 second. The laminate is stored for 24 hours under conditions of 23 ° C. and 50% relative humidity, and the hot melt adhesive is cooled. Next, the cooled laminate is cut into strips having a width of 25 mm in the longitudinal direction (coating direction of the hot melt adhesive) and 150 mm in a direction perpendicular to the longitudinal direction to prepare test pieces.

A test piece is fixed to a tensile tester set to a jig width of 50 mm with a jig so that the direction perpendicular to the longitudinal direction (coating direction of the hot melt adhesive) is positioned up and down, and tested at a tensile speed of 500 mm / min. Pull to the point where the strain displacement of the piece is 50%. Then, it returns to the initial position at a speed of 500 mm / min. The process of pulling up to 50% strain displacement and then returning to the initial position is one cycle, and the same test piece is repeated two cycles. The strain displacement value at which the load is 0.05 N in the first cycle and the strain displacement value at which the load is 0.05 N are measured in the second cycle, and the permanent strain value is calculated based on the following equation: Evaluate stretch recovery.
[Permanent strain (%)] = (Strain displacement value in the second cycle (%))-(Strain displacement value in the first cycle (%))

The adhesiveness of the hot melt adhesive of the present invention is preferably 0.1 N / 25 mm or more, and more preferably 1 N / 25 mm or more. Moreover, the upper limit of the adhesiveness is not particularly limited, and it is preferable that the nonwoven fabric used for the adhesive evaluation is in a “material breakage” state.

The adhesiveness of the hot melt adhesive of the present invention is measured by the following measuring method.

(Measurement method of adhesion)
Using a test piece prepared in the same manner as the stretchability measurement method described above, a T-type peel test in a direction perpendicular to the longitudinal direction (coating direction of the hot melt adhesive) at a tensile speed of 300 mm / min. To measure the adhesive strength. When the nonwoven fabric is torn by the T-type peel test, the material is in a state of destruction exhibiting sufficient adhesive strength, and thus is evaluated as “material breakage”.

The hot melt adhesive of the present invention is suitably used for the production of disposable products. The disposable product is not particularly limited, and examples thereof include so-called sanitary materials such as disposable diapers, sanitary napkins, pet sheets, hospital gowns, and lab coats.

2. Stretch laminate The present invention is also a stretch laminate in which a pair of base materials are joined by the hot melt adhesive.

The method for joining a pair of substrates using the hot melt adhesive of the present invention is not particularly limited, and for example, the following method is used. First, the hot melt adhesive is heated to a molten state. The heating temperature is preferably 140 ° C. or higher, and more preferably 150 ° C. or higher. Further, the heating temperature is preferably 180 ° C. or lower, and more preferably 170 ° C. or lower. Next, a hot melt adhesive in a molten state is applied to one of the substrates. Next, after the other base material is laminated on the coated hot melt adhesive, the hot melt adhesive is cooled and solidified, whereby the pair of base materials can be joined.

The substrate is not particularly limited, and examples thereof include a nonwoven fabric, a hydrophilic fiber material, and a polymer composition film. Especially, the base material which has a stretching property is preferable from a viewpoint which can manufacture the elastic laminated body which has favorable stretching property. Specific examples of stretchable substrates include stretchable nonwoven fabrics and stretchable polymer composition films.

Non-woven fabric is not particularly limited, and generally used non-woven fabrics such as spunbonded non-woven fabric, melt blown non-woven fabric, spunlace non-woven fabric, and air-through non-woven fabric. Among these, a stretchable nonwoven fabric that exhibits stretchability in the longitudinal direction, the direction perpendicular to the longitudinal direction, or both is preferable. By using a stretchable nonwoven fabric, it is possible to form a stretchable laminate that does not hinder the stretchability of the hot melt adhesive and has a good texture.

The stretchable nonwoven fabric is not particularly limited, and a commercially available product can be used. For example, Spunlace nonwoven fabric F6600 manufactured by Suominen, Spunlace nonwoven fabric F2650 manufactured by Suominen, and the like can be given.

The method for applying the molten hot melt adhesive is not particularly limited, and can be applied by a known method. Examples thereof include slot coater coating, roll coater coating, spiral coating, omega coating, control seam coating, curtain spray coating, and dot coating. Coating methods such as slot coater coating and roll coater coating are applied on a flat surface while the hot melt adhesive is in direct contact with the base material, so a relatively small amount of hot melt adhesive is good. Elasticity can be expressed. On the other hand, in the method of applying hot melt adhesive melted in a fiber shape in a non-contact manner, such as spiral coating, omega coating and curtain spray coating, the hot melt adhesive is applied on the substrate. Since an uncoated region is formed, it is suitable for forming a stretchable laminate having air permeability.

The stretchable laminate of the present invention is suitably used as a disposable product. The disposable product is not particularly limited, and examples thereof include so-called sanitary materials such as disposable diapers, sanitary napkins, pet sheets, hospital gowns, and surgical lab coats.

Hereinafter, examples of the present invention will be described. The present invention is not limited to the following examples.

In addition, the raw material used by the Example and the comparative example is as follows.

Styrene block copolymer (A)
-Styrenic block copolymer (A1):
Styrene-Ethylene-Butylene / Styrene-Styrene (SEBSS) Copolymer MD6951 by Clayton Polymer Co., Ltd. (styrene content 34% by mass, Mw = 100,000)
-Styrenic block copolymer (A2):
Styrene-Ethylene-Butylene / Styrene-Styrene (SEBSS) Copolymer A1536 by Clayton Polymer Co., Ltd. (styrene content 42% by mass, Mw = 15,000)
-Styrenic block copolymer (A3):
Styrene-ethylene-butylene-styrene (SEBS) copolymer Asahi Kasei Co., Ltd. H1041 (styrene content 30 mass%, Mw = 61,000)
-Styrenic block copolymer (A4):
Asymmetric Styrene-Isoprene-Styrene (Asymmetric SIS) Copolymer Quintac 3390 (styrene content 48% by mass, Mw = 85,000) manufactured by Nippon Zeon Co., Ltd.
-Styrenic block copolymer (A5):
Styrene-isoprene-styrene (SIS) copolymer TSRC Co., Ltd. Vector 4411 (styrene content 45% by mass, Mw = 75,000)

Tackifying resin (B) :
・ Hydrogenated petroleum resin (B1) HA-103 (softening point 100 ° C) manufactured by TonenGeneral Sekiyu KK
・ Hydrogenated petroleum resin (B2) Escorez 5690 (softening point 90 ° C) manufactured by ExxonMobil

Plasticizer (C) :
・ Paraffinic process oil (C1) PW-32 made by Idemitsu Kosan Co., Ltd.
・ Hydrocarbon synthetic oil (C2) Lucant HC-10 manufactured by Mitsui Chemicals, Inc.
-Liquid paraffin (C3) Kaydol manufactured by Sonneborn
・ Naphthenic process oil (C4) Nyflex 222B made by Nynas

Antioxidants :
・ Phenolic antioxidant BASF IRGANOX1010

(Examples and Comparative Examples)
The above-mentioned raw materials were respectively charged in the stirring and kneading machine equipped with a heating device in the blending amounts shown in Table 1. A hot melt adhesive was produced by kneading while heating at 145 ° C. for 90 minutes.

The characteristics of the obtained hot melt adhesive were evaluated under the following measurement conditions.

(Melt viscosity)
The hot melt adhesive was heated and melted, and the viscosity in a molten state at 140 ° C. and 180 ° C. was measured using a Brookfield RVT viscometer (spindle No. 29) to be η1 and η2, respectively. Moreover, based on the measurement result, the ratio η1 / η2 of melt viscosity at 140 ° C. and 180 ° C. was calculated. It can be evaluated that the closer the value of η1 / η2 is to 1, the better the coating suitability.

(Thermal stability)
20 g of hot-melt adhesive was placed in a 70 ml glass bottle and allowed to stand at 180 ° C. for 3 days with the cover covered with aluminum foil. Subsequently, the carbonization and discoloration of the hot melt adhesive were visually observed under room temperature conditions and evaluated according to the following evaluation criteria. In addition, if evaluation is more than (triangle | delta), it can be evaluated that there is no problem in actual use.
(Double-circle): Carbonization of a hot-melt adhesive agent is not seen, and discoloration is slight.
○: Carbonization of the hot melt adhesive is not observed, but the degree of discoloration is deep.
Δ: Carbonization of the hot melt adhesive is observed, but the degree of discoloration is slight.
X: The carbide | carbonized_material of a hot-melt-adhesive is confirmed, and the degree of discoloration is deep.

(Odor)
20 g of hot-melt adhesive was placed in a 70 ml glass bottle and left at 160 ° C. for 1 hour with the cover covered with aluminum foil. Subsequently, the lid of the aluminum foil was removed under room temperature conditions to confirm the odor of the hot melt adhesive, and evaluation was performed according to the following evaluation criteria. In addition, if evaluation is more than (triangle | delta), it can be evaluated that there is no problem in actual use.
○: No odor is felt.
Δ: Slight odor is felt.
X: A strong odor is felt.

(Stretch recovery)
The hot melt adhesive was applied to the first nonwoven fabric Spunlace nonwoven fabric F2650 by slot coating or curtain spray coating at a coating temperature of 160 to 180 ° C. The coating amount was 50 g / m ² and the coating width was 100 mm. Next, a non-woven fabric F2650 to be a second non-woven fabric is separately prepared, laminated on the first non-woven fabric coated with the hot melt adhesive prepared as described above, and press-bonded at room temperature to obtain a laminate. Was prepared. At this time, the time from when the hot melt adhesive was applied to the first nonwoven fabric until the second nonwoven fabric was laminated and pressure-bonded was 1 second. The laminate was stored for 24 hours under conditions of 23 ° C. and 50% relative humidity, and the hot melt adhesive was cooled. Next, the cooled laminate was cut into strips having a width of 25 mm in the longitudinal direction (coating direction of the hot melt adhesive) and 150 mm in a direction perpendicular to the longitudinal direction to prepare test pieces.

A test piece is fixed to a tensile tester set to a jig width of 50 mm with a jig so that the direction perpendicular to the longitudinal direction (coating direction of the hot melt adhesive) is positioned up and down, and tested at a tensile speed of 500 mm / min. The piece was pulled to a point where the strain displacement was 50%. Subsequently, it returned to the initial position at a speed of 500 mm / min. The process of pulling up to 50% strain displacement and then returning to the initial position was defined as 1 cycle, and the same test piece was repeated 2 cycles. The strain displacement value at which the load is 0.05 N in the first cycle and the strain displacement value at which the load is 0.05 N are measured in the second cycle, and the permanent strain value is calculated based on the following equation: Stretch recovery was evaluated.
[Permanent strain (%)] = (Strain displacement value in the second cycle (%))-(Strain displacement value in the first cycle (%))

(Peelability when stretched)
After the cycle test in the above-described stretch recovery measurement, whether or not the hot melt adhesive and the substrate were peeled off was visually confirmed and evaluated according to the following evaluation criteria.
○: No peeling occurred between the hot melt adhesive and the nonwoven fabric.
X: The hot melt adhesive and the nonwoven fabric are peeled off.

(Adhesiveness)
Using the test piece prepared as described above, adhesive strength is obtained by performing a T-type peel test in a direction perpendicular to the longitudinal direction (coating direction of the hot melt adhesive) at a tensile speed of 300 mm / min. Was measured. When the non-woven fabric was torn by the T-type peel test, the material was in a fractured state exhibiting sufficient adhesive strength, and thus was evaluated as “material breakage”.

The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 ... Elastic laminate, 2 ... Base material, 3 ... Hot melt adhesive, 4 ... Base material

Claims

A hot-melt adhesive containing a styrene block copolymer (A), a tackifier resin (B), and a plasticizer (C),
The styrenic block copolymer (A) includes styrene-ethylene-butylene / styrene-styrene copolymer, styrene-ethylene-propylene / styrene-styrene copolymer, asymmetric styrene-isoprene-styrene copolymer, and asymmetric Containing at least one selected from the group consisting of styrene-butadiene-styrene copolymers,
The hot melt adhesive has a ratio (η1 / η2) of a melt viscosity (η1) at 140 ° C. to a melt viscosity (η2) at 180 ° C. of 5 or less, and a melt viscosity (η2) at 180 ° C. of 8 , 000 mPa · s or less,
A hot melt adhesive characterized by that.
The styrenic block copolymer (A) contains at least one selected from the group consisting of a styrene-ethylene-butylene / styrene-styrene copolymer and an asymmetric styrene-isoprene-styrene copolymer. Item 2. The hot melt adhesive according to Item 1.
The hot melt adhesive according to claim 1 or 2, wherein the content of the plasticizer (C) is 50 to 200 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A).
A stretchable laminate comprising a pair of substrates bonded together by the hot melt adhesive according to any one of claims 1 to 3.