JPH09302319A - Hot-melt adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hut-melt adhesive composition containing a specific ethylene-α-olefin copolymer, styrene-ethylene-propylene-styrene block copolymer and an adhesiveness imparting agent, and suitable for assembling a hygienic material such as a diaper. SOLUTION: This hot-melt adhesive composition contains (A) ethylene-α-olefin copolymer having <=0.90g/cm<3> density, (B) a styrene-ethylene-propylene-styrene block copolymer and (C) an adhesiveness imparting agent. Also, it is preferable to contain (D) a plasticizing oil. Further, as the content of each of the components, 10-80wt.% component (A), 1-50wt.% component (B) and 19-60wt.% component (C) are preferable. Also, in the component (B), the content of styrene is preferably 10-35wt.%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a disposable diaper,
The present invention relates to a hot melt adhesive composition which is preferably used for assembling sanitary products such as sanitary napkins.

[0002]

2. Description of the Related Art Generally, hygiene products such as disposable diapers and sanitary napkins, especially disposable diapers, have a back sheet made of a porous polyethylene film in order to enhance the function of preventing rashes and rashes. The one used for the (outer sheet) and the one using the crotch gather called (b) three-dimensional gather have been proposed and used. In the disposable diaper (a) above, a non-woven fabric is usually used for the top sheet (inner sheet in contact with the skin),
The top sheet is bonded to a back sheet via a hot melt adhesive. The disposable diaper (b) is formed by bonding a three-dimensional gather (wrapping a stretchable material with a non-woven fabric) and the top sheet and / or the back sheet via a hot melt adhesive. And, in the hot melt adhesive used in the disposable diaper of (a) and (b), due to the characteristics of the disposable diaper, a low molecular weight substance in the adhesive exudes to the porous polyethylene film used as the back sheet. Therefore, it is important that performance is not impaired, that when used for assembling the above-mentioned three-dimensional gathers, it does not rash even if it touches the skin, and that it is soft and white or colorless and odorless.

As the above hot melt adhesive, a synthetic rubber hot melt adhesive containing a synthetic rubber as a base polymer has been used. This synthetic rubber-based hot melt adhesive is tacky at room temperature and is in a so-called sticky state, but the amount of a low molecular weight substance that can be contained in the hot melt adhesive is different from that of other polymers. Since the amount of the adhesive used is extremely larger than that of the adhesive used, it is possible to suppress the exudation from the porous polyethylene film used for preventing unevenness. But recently,
From the viewpoint of further softening the texture of the disposable diaper and reducing the cost, the unit weight (weight) of the porous polyethylene film and the nonwoven fabric, which are the constituent materials of the disposable diaper, is reduced. The agent was not able to suppress the appearance of spots even when the basis weight of the base material was thus reduced. Therefore, in a conventional disposable diaper using a synthetic rubber-based hot melt adhesive, due to the appearance of stains, the appearance may be impaired, and problems such as exudation on the skin side and contact with the wearer's skin to cause a rash, That is, there is a problem in that the above performance cannot be satisfied.

Further, as a method for preventing the above-mentioned exudation, it has been considered to reduce the blending amount of the low molecular weight substance in the hot melt adhesive.
Since the adhesive strength is lowered, there is a problem that the desired adhesive strength cannot be obtained. Further, in order to prevent the exposure of the adhesive between the fibers, it has been considered to increase the viscosity of the adhesive, but it has not yet reached a satisfactory level. Further, as an adhesive having a small stickiness, an ethylene-vinyl acetate copolymer (EVA) or an ethylene-α-olefin copolymer is used as a base polymer, and a tackifier resin or wax is added to the EVA-based or α-olefin-based adhesive. Hot melt adhesives are commonly used. This hot melt adhesive has tackiness when melted, and since the base polymer has crystallinity, when cooled after adhesion,
The base polymer crystallizes (hardens into a so-called stiff state) and loses tackiness. Therefore, after cooling, the adhesive has the characteristic that it does not get rash even if it comes into direct contact with the skin. However, since the texture after crystallization is hard, the disposable diaper itself becomes hard, and sometimes the wearer's skin is rubbed and rashed.

Further, in order to soften the texture, it has been considered to add a liquid plasticizer. However, when the liquid plasticizer is added to the hot melt adhesive having the above base polymer, it is tacked even after cooling. It retains strength and adversely affects the skin when used.

In short, the conventionally proposed hot melt adhesives do not satisfy all of the above items 1 to 4, and there is a demand for the development of hot melt adhesives that satisfy all of the items 1 to 3 above. .

Therefore, an object of the present invention is to prevent exudation of low molecular weight substances, to lose tackiness after solidification by cooling, and even when it is used as an adhesive for assembling sanitary articles such as disposable diapers. It is an object of the present invention to provide a hot melt adhesive composition that does not impair the texture of the disposable diaper.

[0008]

The present invention has a permanent set of 5
Hot melt containing 0% or less and a hysteresis ratio of 5.0 or less, an ethylene-α-olefin copolymer, a styrene-ethylene-propylene-styrene block copolymer, and a tackifying resin. The above object is achieved by providing an adhesive composition.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The hot melt adhesive composition of the present invention will be described in more detail below. The hot melt adhesive composition of the present invention comprises a specific ethylene-α-olefin copolymer, styrene-ethylene-propylene-styrene block copolymer (hereinafter referred to as "SEPS"), and a tackifier. It is characterized by

The above-mentioned specific ethylene-α-olefin copolymer used in the hot melt adhesive composition of the present invention has a density of 0.90 g / cm ³ or less, preferably 0.880 to 0.860 g / It is an ethylene-α-olefin copolymer having a cm ³ . The density is 0.90
When it exceeds g / cm ³ , the melt viscosity of the hot melt adhesive becomes too high. Here, the density is measured in the same manner as in the measurement of the density of a known polymer.

The ethylene-α-olefin copolymer is not particularly limited as long as it satisfies the above density.
An ethylene-α-olefin copolymer obtained by copolymerization using a cyclopentadienyl complex as a catalyst is preferable.

In the above ethylene-α-olefin copolymer, the α-olefin to be copolymerized with ethylene is an α-olefin having 3 to 30 carbon atoms, specifically, for example, propylene, 1-butene, 1- Pentene, 1-hexene, 1-octene, 1-heptene, 4-methylpentene-1,4-methylhexene-1,4,4-dimethylpentene-1, octadecene and the like can be mentioned. Among these, 1-hexene, 1-octene, 1-heptene, 4
-Methyl-pentene-1 is preferably used.

In the ethylene-α-olefin copolymer, the cyclopentadienyl complex used as a catalyst when copolymerizing ethylene and α-olefin is a compound represented by the following formula (I): Etc.

ML _X (I) wherein M is a transition metal selected from the group consisting of Zr, Ti, Hf, V, Nb, Ta and Cr, and L is
A ligand having a cyclopentadienyl skeleton, which is a ligand coordinated to the transition metal, a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryl group having 1 to 12 carbon atoms.
Roxy group, C1-C12 trialkylsilyl group, S
O ₃ R group (where R is a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent such as halogen), a halogen atom or a hydrogen atom, and x is the same as the valence of the above transition metal. Is. However, when a plurality of Ls are coordinated, they may be different groups, but at least one is a group having a cyclopentadienyl skeleton. That is,
When x is 1, L is a group having a cyclopentadienyl skeleton, and when x is 2 or more, at least one of a plurality of L is a cyclopentadienyl skeleton. Is a group having ]

Examples of the group having a cyclopentadienyl skeleton include cyclopentadienyl group, methylcyclopentadienyl group, dimethylcyclopentadienyl group, trimethylcyclopentadienyl group, tetramethylcyclopentadienyl group. Enyl group, pentamethylcyclopentadienyl group, ethylcyclopentadienyl group, methylethylcyclopentadienyl group, propylcyclopentadienyl group, methylpropylcyclopentadienyl group,
Alkyl-substituted cyclopentadienyl groups such as butylcyclopentadienyl group, methylbutylcyclopentadienyl group, hexylcyclopentadienyl group; or indenyl group, 4,5,6,7-tetrahydroindenyl group, fluorenyl A group etc. can be illustrated. Further, these groups may be substituted with a halogen atom, a trialkylsilyl group or the like.

As the group having a cyclopentadienyl skeleton, an alkyl-substituted cyclopentadienyl group is particularly preferable among the above-exemplified groups.

When the compound represented by the general formula (I) contains two or more groups having a cyclopentadienyl skeleton, the two groups having a cyclopentadienyl skeleton among them are: It may be bonded via an alkylene group such as ethylene and propylene; a substituted alkylene group such as isopropylidene and diphenylmethylene; a silylene group or a substituted silylene group such as a dimethylsilylene group, a diphenylsilylene group, and a methylphenylsilylene group.

Examples of the hydrocarbon group having 1 to 12 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group. More specifically, the alkyl group is a methyl group, Ethyl group, propyl group,
Examples include isopropyl group and butyl group, examples of cycloalkyl group include cyclopentyl group and cyclohexyl group, examples of aryl group include phenyl group and tolyl group, and examples of aralkyl group include benzyl group and neophyll group. Examples include groups. Examples of the alkoxy group include methoxy group, ethoxy group, butoxy group, etc., examples of the aryloxy group include phenoxy group, etc., and examples of the halogen atom include fluorine, chlorine, bromine, iodine and the like.

Examples of the SO ₃ R group include p-toluenesulfonato group, methanesulfonato group, trifluoromethanesulfonato group and the like.

The compound containing a group having such a cyclopentadienyl skeleton is more specifically represented by the following formula (II) when the valence of the transition metal is 4.

R ² _k R ³ _l R ⁴ _m R ⁵ _n M ... (II) [wherein, M is the above transition metal, and R ² is a group having a cyclopentadienyl skeleton (ligand ), And R ³ , R
⁴ and R ⁵ are each a group having a cyclopentadienyl skeleton, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a trialkylsilyl group, a SO ₃ R group, a halogen atom or a hydrogen atom. Where k is an integer greater than or equal to 1, and k + 1 + m
+ N = 4. ]

In the present invention, in the above formula (II), R
^A compound in which at least two of ² , R ³ , R ⁴ and R ⁵ , for example, R ² and R ³ are groups (ligands) having a cyclopentadienyl skeleton is preferably used. The skeleton-bearing groups (eg R ² and R ³ ) may be attached as described above.

Specific examples of the above compounds in which M is zirconium are shown below. Bis (indenyl) zirconium dichloride, bis (indenyl) zirconium dibromide, bis (indenyl) zirconium bis (p-toluenesulfonato) bis4,5,6,7-
Tetrahydroindenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dibromide, ethylenebis (indenyl) dimethylzirconium, ethylenebis (indenyl) diphenylzirconium, ethylenebis ( Indenyl) methyl zirconium monochloride, ethylene bis (indenyl) zirconium bis (methane sulfonate), ethylene bis (indenyl) zirconium bis (p-toluene sulfonate), ethylene bis (indenyl) zirconium bis (trifluoromethane sulfonate), ethylene Bis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, isopropylidene (cyclopenta Enyl - fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl - methylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (cyclopentadienyl)
Zirconium dichloride, dimethylsilylene bis (methylcyclopentadienyl) Zirconium dichloride, dimethylsilylene bis (dimethylcyclopentadienyl)
Zirconium dichloride, dimethyl silylene bis (trimethylcyclopentadienyl) zirconium dichloride, dimethyl silylene bis (indenyl) zirconium dichloride, dimethyl silylene bis (indenyl) zirconium bis (trifluoromethane sulfonate), dimethyl silylene bis (4,5,6,6) 7-Tetrahydroindenyl) zirconium dichloride, dimethylsilylenebis (cyclopentadienyl-fluorenyl) zirconium dichloride, diphenylsilylenebis (indenyl)
Zirconium dichloride, methylphenylsilylene bis (indenyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dibromide, bis (cyclopentadienyl) methylzirconium monochloride, bis (cyclopentadiene) Dienyl) ethyl zirconium monochloride, bis (cyclopentadienyl) cyclohexyl zirconium monochloride, bis (cyclopentadienyl) phenyl zirconium monochloride, bis (cyclopentadienyl) benzyl zirconium monochloride, bis (cyclopentadienyl) ) Zirconium monochloride monohydride, bis (cyclopentadienyl) methyl zirconium monohydride, bis (cyclopentadienyl) Methylzirconium, bis (cyclopentadienyl) diphenylzirconium, bis (cyclopentadienyl) dibenzylzirconium, bis (cyclopentadienyl) zirconium methoxychloride, bis (cyclopentadienyl) zirconium ethoxy chloride, bis (cyclopentapenta Dienyl) zirconium bis (methanesulfonato), bis (cyclopentadienyl) zirconium bis (p-toluenesulfonato), bis (cyclopentadienyl) zirconium bis (trifluoromethanesulfonato), bis (methylcyclopentadiene) (Enyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium ethoxy chloride, bis (dimethylcyclopente) Dienyl) zirconium bis (trifluoromethanesulfonato), bis (ethylcyclopentadienyl) zirconium dichloride, bis (methylethylcyclopentadienyl) zirconium dichloride, bis (propylcyclopentadienyl) zirconium dichloride, bis (methylpropylcyclo) Pentadienyl) zirconium dichloride, bis (butylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium bis (methanesulfonate), bis (trimethyl) Cyclopentadienyl) zirconium dichloride, bis (tetramethylcyclopentadienyl) zirconium dichloride, bis (pentamethylcyclopentadiene Enyl) zirconium dichloride, bis (hexylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylcyclopentadienyl)
Zirconium dichloride.

In the above-exemplified compounds, disubstituted cyclopentadienyl rings such as dimethylcyclopentadienyl include 1,2- and 1,3-substituted compounds,
Trisubstituted compounds such as dimethylcyclopentadienyl are 1,2,2
Includes 3- and 1,2,4-substitutes. Also propyl,
Alkyl groups such as butyl are n-, i-, sec-, te
Including isomers such as rt-. Further, examples of the compound include a cyclopentadienyl complex in which zirconium is replaced with titanium, hafnium, vanadium, niobium, tantalum, or chromium in the above compound in which M is zirconium.

Further, the cyclopentadienyl complex is
When used, they can be used alone or as a mixture. It may be used after being diluted with a hydrocarbon or a halogenated hydrocarbon. Particularly, in the present invention, a zirconocene compound having a central metal atom of zirconium and a ligand having a group having at least two cyclopentadienyl skeletons is preferably used as the cyclopentadienyl complex.

The above cyclopentadienyl complex is
It can also be used in combination with a usual aluminoxane compound or a compound which reacts with the cyclopentadienyl complex to form a stable anion.

The cyclopentadienyl complex catalyst used in the present invention is described in JP-A-4-253711,
Japanese Unexamined Patent Publication (Kokai) No. 4-279592 and Japanese Patent Publication No. 6-50358.
No. 5, JP-A No. 3-188092, or JP-A No.
The polymerization catalyst described in JP-A-84407 can also be used.

The blending ratio of ethylene and α-olefin in the ethylene-α-olefin copolymer is preferably 40 to 98% by weight of ethylene and 60 to 2% by weight of α-olefin.

The above ethylene-α-olefin copolymer is obtained by mixing ethylene and α-olefin in the presence of a cyclopentadiene complex in an amount of 100 to 3,000 kg / c.
m ² , preferably 300 to 2,000 kg / cm ² , 1
It can be produced by polymerizing by a high pressure ionic polymerization method at a temperature of 25 to 250 ° C., preferably 150 to 200 ° C. In particular, in order to polymerize the cyclopentadienyl complex and the aluminoxane compound in combination, the method described in JP-A-6-61 is disclosed.
No. 1-130314, No. 60-35006,
Stable anions according to the methods described in JP-A-58-19309, JP-A-60-35008, JP-A-3-163088, etc., and by reacting with the cyclopentadienyl complex and the cyclopentadienyl complex. In order to polymerize the compound forming the compound in combination, European Patent No. 277,004, International Publication WO92 / 0172
Polymerization can be carried out according to the high-pressure ionic polymerization method described in JP-A No. 3 (Kokai) No. 3 and the like.

The MFR of the above ethylene-α / olefin copolymer (JIS K-7210; 190 ° C., 2.
(Measured under a load of 16 kg) is preferably 0.5 to 500 g
/ 10 minutes.

The ethylene-α-olefin copolymer has a permanent strain of preferably 50% or less, more preferably 0 to 30%, and a hysteresis ratio of 5.0 or less, and further preferably. It is preferably 1.0 to 3.5. On the other hand, the permanent set exceeds 50%,
Alternatively, when the above hysteresis ratio exceeds 5.0, the melt viscosity of the hot melt adhesive tends to increase, which is not preferable.

The permanent set and the hysteresis ratio are
Each is measured as follows. Measurement method of permanent strain: In the same manner as the measurement method of the hysteresis ratio described below, after elongating the sample by 100%, measure the length of the sample as the initial distance between chucks, and measure the initial length when elongating 100%. The ratio (%) of the non-relaxable length (length of the portion elongated and longer than the initial length) to the length (the initial distance between the chucks) was determined, and this was defined as the permanent strain. Hysteresis ratio measurement method; To examine the elasticity of each sample,
The hysteresis ratio was measured using an elongation tester with an integrating device. That is, a sample having a width of 25 mm was prepared using the elastic member, and the sample was placed on the tester with a distance between chucks of 100 m.
m and then each sample is 300 mm /
100% stretching at a speed of 10 min to form a stretching curve, and then loosening at the same speed to make the gap between the chucks equal to the initial length of 10%.
Relaxation was stopped at 0 mm to form a relaxation curve, the area under the stretching curve and the area under the relaxation curve were measured, and these were substituted into the following equation to calculate the hysteresis ratio. Hysteresis ratio = Area under stretch curve / Area under relaxation curve

The SE used in the present invention
PS is a component that can suppress the exudation of the low-molecular weight substance because it contains a large amount of low-molecular weight substance that can be contained in the polymer, and has an ethylene structure and a propylene structure between the styrene polymer blocks at both ends. It has a structure in which In addition, the above SEPS is
Since it has the same skeleton in chemical structure as the ethylene-α / olefin copolymer, other synthetic rubbers such as styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SB
S), styrene-ethylene-butylene-styrene copolymer (SEBS) and the like, having good compatibility with the ethylene-α-olefin copolymer, and low-temperature adhesiveness of the obtained adhesive composition. Can be greatly improved.

The content of styrene in the SEPS is preferably in the range of 10 to 35% by weight. If the content is less than 10% by weight, tackiness remains after cooling, and if it exceeds 35% by weight, low-temperature adhesiveness tends to be deteriorated, which is not preferable.

The above SEPS can be obtained, for example, by hydrogenating the isoprene polymer portion of the styrene-isoprene-styrene block copolymer in which the styrene polymer blocks at both ends are isoprene polymer blocks.

The tackifying resin used in the present invention is not particularly limited as long as it is used in a usual hot melt adhesive composition.
Hydrogenated resins such as hydrogenated aromatic petroleum resin, hydrogenated aliphatic petroleum resin, hydrogenated terpene resin, etc. have double bonds due to their chemical structure due to hydrogenation. Since the amount is extremely small, the stability to heat is good, and there is no problem of change in hue or odor due to deterioration over time, and therefore it is particularly preferably used. Further, since such a tackifying resin has excellent compatibility with the ethylene-α-olefin copolymer and SEPS, the adhesiveness is not hindered by its use.
The softening temperature of the tackifying resin is not particularly limited, and may be solid or liquid at room temperature, but liquid is preferable because it has an effect as a plasticizer.

In the hot melt adhesive composition of the present invention, the content of the ethylene-α.olefin copolymer is preferably 10 to 80% by weight, more preferably 15%.
The content of the styrene-styrene-propylene-styrene block copolymer is preferably 1 to 50% by weight, more preferably 5 to 30% by weight, and the content of the tackifying resin is Is preferably 19 to 6
It is 0% by weight, more preferably 30 to 50% by weight.
Here, the above-mentioned content is% when the total amount of the components not containing the additives described later is 100. In particular,
The ethylene-α / olefin copolymer, the SEP
It is a weight% when the total amount of S, the tackifying resin, and a plasticizer used as needed, which will be described later, is 100. When the blending amount of the ethylene-α / olefin copolymer is less than 10% by weight, the cohesive force of the hot melt adhesive becomes low, which is not preferable. On the other hand, if it exceeds 80% by weight, the melt viscosity of the hot melt adhesive becomes too high, which is not preferable. When the compounding amount of the SEPS is less than 1% by weight, the compatibility is deteriorated, and conversely, when it exceeds 50% by weight,
It is not preferable because the low-temperature adhesiveness and texture may deteriorate. When the content of the tackifying resin is more than 60% by weight, the texture becomes hard and the low temperature adhesiveness deteriorates,
If it is less than 19% by weight, the wettability with respect to the adherend may be lowered and the initial adhesive strength may be deteriorated, which is not preferable.

Further, the hot-melt adhesive composition of the present invention contains the above ethylene-α.olefin copolymer and the above S.
In addition to EPS and the tackifying resin, a plasticizer may be blended if necessary. The above-mentioned plasticizer is not particularly limited as long as it is used in the hot melt adhesive composition, and conventionally known ones are used, and examples thereof include plasticized oil. Such a plasticizer may be liquid or solid. When the above-mentioned plasticizer is used, the compounding amount of the plasticizer is preferably 1 to 4 from the viewpoint of the solidification time of the adhesive and the tack strength after solidification.
It is 0% by weight, more preferably 5 to 30% by weight.

Further, in addition to the above-mentioned components, the hot melt adhesive composition of the present invention may further contain conventionally known additives such as antioxidants, stabilizers, fillers and pigments, if necessary. They can be selected and blended, and they can be used alone or as a mixture. Further, various thermoplastic polymer compounds may be added in addition to the above additives.

The hot-melt adhesive composition of the present invention can be put to use, for example, by putting the above-mentioned raw materials in respective molten bean-mixing kettles and mixing them by heating.

The hot-melt adhesive composition of the present invention is useful as an adhesive for the production of disposable diapers and sanitary napkins (specifically, for laminating members such as a top sheet and a back sheet). Besides, it is suitable for bookbinding, cardboard manufacturing, and the like.

[0042]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these.
The methods for measuring various physical properties in the examples are as follows.

<Adhesiveness> A polyethylene film (specifically, 35 g / m ² moisture-permeable sheet made by Kao) and a non-woven fabric (specifically polyethylene terephthalate (PET, core) / polyethylene (PE, mainly used in paper diapers) sheath)
Non-woven fabric composed of core-sheath fibers and having a basis weight of 20 g / m ² ] was prepared. Then, the polyethylene film and the non-woven fabric were applied in a bead form at a coating temperature of 120 to 150 ° C. and a coating amount of 0.05 g / m ² using the hot melt adhesive composition obtained in the example, and adhered. A test piece was obtained. The obtained test piece was left in a temperature atmosphere of 20 ° C. for 24 hours and then taken out, and both of them adhered by hand were peeled off. When the material was broken, the sample was evaluated as ◯, when the interface was separated, as ×, and the middle was evaluated as Δ. did. Further, similarly, the case where the nonwoven fabrics were adhered to each other was also evaluated.

<Tack Force> The hot-melt adhesive composition obtained in the example was applied to a polyester film having a thickness of 50 μm in a thickness of 50 μm. 25mm x 125m
It was cut into m pieces, and the cut pieces were formed into a loop with the surface coated with the adhesive composition facing outward, and this was used as a sample. This sample was 300 mm /
It was adhered to an adherend (polyethylene plate) having a width of 25 mm for min, and then the force when the sample and the adherend were peeled off when pulled up at the same speed was measured. The measurement was performed twice, immediately after coating and 1 hour after coating.
The average of 5 samples was used as the measured value.

<Hardness> Diameter 65 m in a temperature atmosphere of 20 ° C.
The hot-melt adhesive composition melted in a ring having a depth of m and a depth of 12 mm was poured into the ring, cooled and solidified, and then measured with a predetermined hardness meter (according to JIS K6301). <Exuding property> A hot-melt adhesive composition having a thickness of 50 μm was applied to a polyester film having a thickness of 50 mm, and this was used as a test sample and laminated with a commercially available 30 g / cm ² porous polyethylene film, and the temperature was adjusted to 1 at 60 ° C. Left for a week. Then, the degree of exudation thereafter was visually determined. ○ When the hiding property of the film is secured without any exudation, × when the film is completely exuded, △ in the middle
And

<Thermal stability> Viscosity decrease rate The hot melt adhesive compositions obtained in the examples were allowed to stand for 72 hours in a temperature atmosphere of 180 ° C., and the viscosity before and after that was measured to calculate the viscosity decrease rate. This was used as an index of thermal stability. The calculation formula is as follows. Viscosity decrease rate [(V ₀ −V) / V ₀ ] × 100 (%) V: Melt viscosity at 160 ° C. of the hot melt adhesive composition after standing for 180 hours at 180 ° C. V ₀ : Melt viscosity at 160 ° C. of the hot melt adhesive composition before being subjected to heat history. Hue It was left for 72 hours in a temperature atmosphere of 180 ° C., and the hue of the composition at that time was visually evaluated. ○ indicates complete colorless or white color, △ indicates slightly colored, and X indicates clearly colored. Odor The sample was left for 72 hours in a temperature atmosphere of 180 ° C., and the odor of the composition at that time was evaluated by a sensory test (10 panelists). ○ for odorless, △ for slightly odorous,
The case where there was an obvious odor was marked with x.

[Examples] Each hot-melt adhesive composition was prepared by mixing the components in the formulation shown in [Table 1] and further melt-kneading at 150 ° C. Each of the above-mentioned evaluations was performed on the obtained hot melt adhesive composition. The results are shown in [Table 2].

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

The hot melt adhesive composition of the present invention comprises:
There is no exudation of low molecular weight substances, the tack force disappears after cooling and solidification, and even when used as an adhesive for assembling hygiene products such as disposable diapers, the texture of the disposable diapers is not impaired. Is.

Claims (4)

[Claims] 1. An ethylene-α-olefin copolymer having a density of 0.90 g / cm ³ or less, styrene-ethylene-
A hot-melt adhesive composition comprising a propylene-styrene block copolymer and a tackifying resin. 2. The content of the ethylene-α-olefin copolymer is 10 to 80% by weight, and the content of the styrene-styrene-propylene-styrene block copolymer is 1 to 50% by weight. The hot melt adhesive composition according to claim 1, wherein the content of the tackifying resin is 19 to 60% by weight. 3. The styrene-ethylene-propylene-
The hot melt adhesive composition according to claim 1, wherein the content of styrene in the styrene block copolymer is 10 to 35% by weight. 4. The method according to claim 1, further comprising a plasticizing oil.
The hot melt adhesive composition according to any one of 1 to 3.