JP2015145471A - hot melt adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot melt adhesive that has high fluidity during when melted, exhibits high adhesive strength between PP nonwoven fabrics, and has high adhesiveness with PE film/PP nonwoven fabric and long-term stability.SOLUTION: A hot melt adhesive comprises (A) a propylene homopolymer that satisfies (i) to (iii) below and (B) a styrene random copolymer: (i) the tensile modulus of elasticity at 23°C is 400 MPa or less, (ii) the weight-average molecular weight (Mw) is 10,000 to 150,000, and (iii) Mw/Mn is 2.5 or less.

Description

  The present invention relates to a hot melt adhesive containing a propylene homopolymer as an essential component.

  Hot-melt adhesives are solventless adhesives. After being applied to the adherend by heating and melting, it is solidified by cooling and expresses adhesiveness, allowing instant bonding and high-speed bonding. It is used in a wide range of fields. Adhesive materials to be bonded with hot melt adhesives and their use conditions vary, and various hot melt adhesives have been developed and supplied to the market for various applications. Various operating temperatures are assumed.

As a conventional hot melt adhesive, an ethylene-vinyl acetate copolymer, or a thermoplastic elastomer such as a styrene-butadiene-styrene block copolymer or a styrene-isoprene-styrene block copolymer is used as a base polymer, The resin composition which mix | blended tackifier resin and the plasticizer with this is mainly used.
However, hot-melt adhesives manufactured using the base polymer as described above have poor thermal stability during heating, cause oxidation, gelation, decomposition, coloration, etc. during coating, and the strength of the bonded portion is deteriorated over time. There were problems such as causing changes.
Propylene polymers have been conventionally used as base polymers for hot melt adhesives. Among them, low molecular weight polypropylene polymerized with a metallocene-based catalyst has high fluidity and excellent coating properties when used as a hot-melt adhesive, excellent adhesion strength of low-polar substances such as PP, and heat stability during heating and melting. Since it is excellent in properties, it can be suitably used as a base polymer for various hot melt adhesives (Patent Document 1). It is particularly suitable for spray coating used in the assembly of sanitary materials such as paper diapers and sanitary products.

International Publication No. 03/091289

The hot melt adhesive having a polypropylene as a base polymer described in Patent Document 1 exhibits high adhesive strength in bonding of non-woven polypropylene fabrics (hereinafter also referred to as “PP non-woven fabric”), but other materials constituting sanitary materials In particular, there is a problem that the adhesive strength with a polyethylene film (hereinafter also referred to as “PE film”) is inferior to that of conventionally used elastomeric hot melt adhesives. In addition, the adhesive strength may decrease during the storage process from pasting to use.
It is an object of the present invention to provide a hot melt adhesive having high fluidity at the time of melting, exhibiting high adhesive strength between PP nonwoven fabrics, and further having high adhesiveness of PE film-PP nonwoven fabric and long-term stability. And

The present invention relates to the following [1] to [8].
[1] (A) a propylene homopolymer satisfying the following (i) to (iii):
(B) A hot melt adhesive containing a styrene random copolymer.
(I) Tensile modulus at 23 ° C. is 400 MPa or less (ii) Weight average molecular weight (Mw) is 10,000 to 150,000
(Iii) Mw / Mn is 2.5 or less [2] (B) The hot melt adhesive according to [1], wherein the styrene random copolymer is a hydrogenated styrene copolymer.
[3] The hot melt adhesive according to [1] or [2], wherein the content of the (A) propylene homopolymer is 1 to 50 parts by mass with respect to 100 parts by mass of the hot melt adhesive.
[4] The hot water according to any one of [1] to [3], wherein the content of (B) the styrene random copolymer is 1 to 50 parts by mass with respect to 100 parts by mass of the hot melt adhesive. Melt adhesive.
[5] The hot melt adhesive according to any one of [1] to [4], wherein (B) the styrenic random copolymer is a random copolymer of an aromatic vinyl compound and a conjugated diene.
[6] The hot melt adhesive according to [5], wherein the content of the structural unit derived from the aromatic vinyl compound in the (B) styrene random copolymer is 1 to 40% by mass.
[7] The hot melt adhesive according to [5] or [6], wherein the content of the structural unit derived from the conjugated diene in (B) the styrene random copolymer is 60 to 99% by mass.
[8] The hot melt adhesive according to any one of [1] to [7], wherein the (B) styrenic random copolymer has a breaking elongation of 700% or more and a tensile modulus of 10 MPa or less.

According to the present invention, it is possible to provide a hot melt adhesive having high fluidity at the time of melting, exhibiting high adhesive strength between PP nonwoven fabrics, and further having high adhesion and long-term stability of PE film-PP nonwoven fabric. it can.
The hot melt adhesive of the present invention has improved long-term stability in addition to applicability, adhesiveness of low-polarity substances, and thermal stability during heat-melting, so that it can be used for the production of sanitary materials such as disposable diapers. It can be particularly suitably used as a hot melt adhesive.

The hot melt adhesive of the present invention includes (A) a propylene homopolymer satisfying the following (i) to (iii), and (B) a styrene random copolymer.
(I) Tensile modulus at 23 ° C. is 400 MPa or less (ii) Weight average molecular weight (Mw) is 10,000 to 150,000
(Iii) Mw / Mn is 2.5 or less The hot melt adhesive of the present invention has high fluidity at the time of melting, exhibits high adhesive strength between PP nonwoven fabrics, and further exhibits high adhesiveness of PE film-PP nonwoven fabric and Has its long-term stability. This is a combination of a predetermined (A) propylene homopolymer and (B) a styrene random copolymer, which suppresses deterioration of the resin itself, increases compatibility of components, suppresses changes over time, It is considered that long-term stability in strength was obtained.

[(A) Propylene homopolymer]
(A) The propylene homopolymer satisfies the following (i) to (iii) in order to increase the fluidity at the time of melting of the hot melt adhesive and to obtain high adhesive strength between the PP nonwoven fabrics.
(I) Tensile modulus at 23 ° C. is 400 MPa or less (ii) Weight average molecular weight (Mw) is 10,000 to 150,000
(Iii) Mw / Mn is 2.5 or less The measuring method of various numerical values is based on the method described in the examples.

(I) Tensile modulus (A) The propylene homopolymer has a tensile modulus at 23 ° C. of 400 MPa or less. A lower tensile elastic modulus is preferable from the viewpoint of adhesiveness, and the lower limit thereof is not particularly limited, and the measurement limit value is the lower limit. Specifically, the tensile elastic modulus is preferably 1 MPa or more, more preferably 5 MPa or more, and further preferably 10 MPa or more.
For example, when a polyethylene film is used as the adherend, moderate flexibility is required from the viewpoint of the followability of the hot melt adhesive to the adherend and the adhesion to the unevenness of the adherend surface. The From such a viewpoint, the tensile elastic modulus at 23 ° C. of the propylene homopolymer of the present invention is 400 MPa or less, preferably 350 MPa or less, more preferably 300 MPa or less, still more preferably 250 MPa or less, and still more preferably 200 MPa or less. More preferably, it is 150 MPa or less.
For example, when using a non-woven fabric as the adherend, moderate flexibility is required from the viewpoint of bleeding of the hot melt adhesive onto the adherend and the anchor effect on the unevenness of the adherend surface. Is done. From such a viewpoint, the tensile elastic modulus at 23 ° C. of the propylene homopolymer of the present invention is 400 MPa or less, preferably 350 MPa or less, more preferably 300 MPa or less, still more preferably 250 MPa or less, and still more preferably 200 MPa or less. More preferably, it is 150 MPa or less.
The tensile elastic modulus of the propylene homopolymer of the present invention is measured by the method described in the examples.
The tensile modulus of the propylene homopolymer of the present invention can be adjusted within a desired range by changing the polymerization conditions (reaction temperature, reaction time, catalyst, promoter) of the propylene homopolymer. .

(Ii) Weight average molecular weight (Mw)
The propylene homopolymer has a weight average molecular weight of 10,000 to 150,000. When the weight average molecular weight is 10,000 to 150,000, the fluidity and adhesiveness at the time of melting are excellent. From such a viewpoint, the weight average molecular weight is preferably 10,000 to 150,000, more preferably 15,000 to 140,000, and more preferably 15,000 to 130,000. The weight average molecular weight can be controlled by appropriately adjusting the polymerization conditions (propylene pressure, polymerization time, etc.).

(Iii) Molecular weight distribution (Mw / Mn)
The propylene homopolymer has a molecular weight distribution (Mw / Mn) of 2.5 or less. If the molecular weight distribution is 2.5 or less, the fluidity at the time of melting is excellent. From such a viewpoint, the molecular weight distribution is preferably 2.4 or less, more preferably 2.2 or less. From the viewpoint of productivity, the molecular weight distribution is preferably 1.1 or more, more preferably 1.3 or more. By using a metallocene catalyst, the molecular weight distribution (Mw / Mn) can be 2.5 or less.

(Iv) Mesopentad fraction [mmmm]
The propylene homopolymer has a mesopentad fraction [mmmm] of preferably 20 to 80 mol%. When [mmmm] is 20 to 80 mol%, the fluidity and adhesiveness at the time of melting are excellent. From such a viewpoint, the mesopentad fraction [mmmm] is preferably more than 20 mol% and 80 mol% or less, more preferably more than 40 mol% and 75 mol% or less. It is possible to control the mesopentad fraction by adjusting the monomer concentration and the reaction pressure.

(V) Intrinsic viscosity [η]
The propylene homopolymer has an intrinsic viscosity [η] of preferably 0.01 to 2.0 deciliter / g, more preferably 0.1 to 1.5 deciliter / g, and still more preferably 0, from the viewpoint of applicability. 2 to 1.0 deciliter / g. The intrinsic viscosity [η] is determined by the measurement method described in the examples. The intrinsic viscosity [η] can be controlled by adjusting the polymerization conditions (propylene pressure, polymerization time, etc.).

(Vi) Melting point (Tm-D)
The melting point (Tm-D) of the propylene homopolymer is preferably 0 to 140 ° C, more preferably 20 to 120 ° C, and still more preferably 40 to 100 ° C, from the viewpoint of improving open time and improving creep resistance.
In the present invention, a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer Co., Ltd.) is used, and 10 mg of a sample is held at −10 ° C. for 5 minutes in a nitrogen atmosphere and then heated at 10 ° C./min. The peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by the above is defined as the melting point (Tm-D). It is possible to control the melting point by adjusting the monomer concentration and the reaction pressure.

(Propylene homopolymer production method)
As a manufacturing method of a propylene homopolymer, the method of manufacturing a propylene homopolymer by homopolymerizing propylene using a metallocene catalyst is mentioned.
Examples of the metallocene catalyst include JP-A-58-19309, JP-A-61-130314, JP-A-3-163088, JP-A-4-300787, JP-A-4-21694, and special tables. Transition metal compounds having one or two ligands such as a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, and the like, as described in JP-A-1-502036 Examples thereof include a catalyst obtained by combining a transition metal compound whose ligand is geometrically controlled and a promoter.

  Among metallocene catalysts, it is preferable that the ligand comprises a transition metal compound in which a crosslinked structure is formed via a crosslinking group, and in particular, a transition in which a crosslinked structure is formed via two crosslinking groups. A method using a metallocene catalyst obtained by combining a metal compound and a cocatalyst is more preferable. Examples described in paragraphs “0037” to “0084” of JP-A No. 2001-172325 are also preferable examples in the present invention.

  (A) The content of the propylene homopolymer is preferably with respect to 100 parts by mass of the hot melt adhesive in order to increase the fluidity at the time of melting of the hot melt adhesive and to obtain high adhesive strength between the PP nonwoven fabrics. Is 1-50 parts by mass, more preferably 5-40 parts by mass, still more preferably 8-30 parts by mass.

[(B) Styrene random copolymer]
The styrenic random copolymer in the present invention is a random copolymer of an aromatic vinyl compound and another monomer, preferably a random copolymer of an aromatic vinyl compound and a conjugated diene. By using a random copolymer, excellent long-term stability can be obtained.
“Aromatic vinyl compound” means an aromatic hydrocarbon compound having a vinyl group. For example, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2, 4-dimethyl styrene, vinyl naphthalene, vinyl anthracene, etc. are mentioned.
Of these, styrene is preferred. These aromatic vinyl compounds can be used alone or in combination of two or more.
“Conjugated diene” means a diolefin compound having at least a pair of conjugated double bonds. Examples of the conjugated diene include 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Is mentioned. Among these, 1,3-butadiene and 2-methyl-1,3-butadiene are preferable. These conjugated diene compounds can be used alone or in combination of two or more.

(B) Content of the structural unit derived from the aromatic vinyl compound of a styrene random copolymer becomes like this. Preferably it is 1-40 mass%, More preferably, it is 2-30 mass%, More preferably, it is 5-20 mass%. .
(B) Content of the structural unit derived from the conjugated diene of a styrene random copolymer becomes like this. Preferably it is 60-99 mass%, More preferably, it is 70-98 mass%, More preferably, it is 80-95 mass%.
(B) The styrene random copolymer may be either hydrogenated or non-hydrogenated, but in order to obtain excellent long-term stability, the hydrogenated styrene random copolymer may be used. Polymers are preferred.

(B) The styrene random copolymer preferably has a breaking elongation of 700% or more and a tensile modulus of 10 MPa or less.
(B) The elongation at break of the styrene random copolymer is preferably 700% or more, more preferably 800% or more. When the elongation at break is 700% or more, the adhesive is stretched and the adhesive strength is improved. The elongation at break is preferably 1200% or less, more preferably 1100% or less.
(B) The tensile elastic modulus of the styrene random copolymer is preferably 10 MPa or less, more preferably 5 MPa or less, and still more preferably 3 MPa or less. When the tensile elastic modulus is 10 MPa or less, the adhesive is extended and the adhesive strength is improved. The tensile elastic modulus is preferably 0.1 MPa or more, more preferably 1 MPa or more.
The measuring method of breaking elongation and a tensile elasticity modulus are based on the measuring method as described in an Example.

  (B) As a commercial item of a styrene random copolymer, Dynalon 1321P (manufactured by JSR Corporation) and the like can be mentioned.

  (B) The content of the styrenic random copolymer is preferably 1 to 50 parts by mass, more preferably 2 with respect to 100 parts by mass of the hot melt adhesive in order to obtain excellent adhesiveness and long-term stability. -30 mass parts, More preferably, it is 3-25 mass parts.

[(C) Tackifying resin]
The hot melt adhesive of the present invention may contain a tackifying resin.
Examples of the tackifying resin include a solid, semi-solid or liquid resin at room temperature composed of a hydrogenated derivative of an aliphatic hydrocarbon petroleum resin, a rosin derivative resin, a polyterpene resin, a petroleum resin, an oil-soluble phenol resin, or the like. be able to. You may use these individually or in combination of 2 or more types. In the present invention, it is preferable to use a hydrogenated product in consideration of compatibility with the base polymer. Among these, a hydrogenated derivative of an aliphatic hydrocarbon petroleum resin having excellent thermal stability is more preferable.
The content of the tackifying resin is preferably 20 to 60 parts by mass with respect to 100 parts by mass of the hot-melt adhesive, from the viewpoints of improvement in tackiness, applicability, and improvement in wettability to the adherend due to viscosity reduction. More preferably, it is 30-60 mass parts.

[(D) Oil]
The hot melt adhesive of the present invention may contain oil.
Examples of the oil include paraffinic process oil and naphthenic process oil.
The content of the oil is preferably 5 to 40 parts by mass, more preferably 100 parts by mass with respect to 100 parts by mass of the hot melt adhesive, from the viewpoints of improvement in tackiness, applicability, and improvement in wettability to the adherend due to viscosity reduction. Is 10-30 parts by mass.

[(E) Wax]
The hot melt adhesive of the present invention may contain a wax.
Examples of the wax include animal wax, plant wax, carnauba wax, candelilla wax, wood wax, beeswax, mineral wax, petroleum wax, paraffin wax, microcrystalline wax, petrolatum, higher fatty acid wax, higher fatty acid ester wax, Fischer Examples include Tropsch wax.
The content of the wax is preferably 5 to 40 parts by mass, more preferably 10 to 30 parts with respect to 100 parts by mass of the hot-melt adhesive, from the viewpoints of coatability and improvement of wettability to the adherend due to viscosity reduction. Part by mass.

[Other additives]
The hot melt adhesive of the present invention may contain, for example, a plasticizer, an inorganic filler, an antioxidant and the like.
Examples of the plasticizer include phthalic acid esters, adipic acid esters, fatty acid esters, glycols, and epoxy polymer plasticizers.
Examples of the inorganic filler include clay, talc, calcium carbonate, barium carbonate and the like.
Examples of the antioxidant include trisnoniphenyl phosphite, distearyl pentaerythritol diphosphite, ADK STAB 1178 (manufactured by ADEKA Corporation), Stamilizer TNP (manufactured by Sumitomo Chemical Co., Ltd.), Irgaphos 168 (manufactured by BASF Corporation), Phosphorus antioxidants such as Sandstab P-EPQ (Sand Corp.), 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (3 ′, 5′-di-t-butyl) -4′-hydroxyphenyl) propionate, Sumilizer BHT (manufactured by Sumitomo Chemical Co., Ltd.), Irganox 1010 (manufactured by BASF), phenolic antioxidants, dilauryl-3,3′-thiodipropionate, pentaerythritol tetrakis (3-laurylthiopropionate), Sumilyzer TP Sulfur-based antioxidants such as L (manufactured by Sumitomo Chemical Co., Ltd.), Yoshinox DLTP (manufactured by Yoshitomi Pharmaceutical Co., Ltd.) and Anthiox L (manufactured by NOF Corporation).

[Method for producing hot melt adhesive]
In the hot melt adhesive of the present invention, (A) propylene homopolymer and (B) styrenic random copolymer are preferably used as the base polymer, preferably (C) tackifying resin, (D) oil, and (E) wax. Further, if necessary, various additives can be dry-blended using a Henschel mixer or the like, and melt-kneaded with a single-screw or twin-screw extruder, a plast mill, a Banbury mixer, or the like.

  The hot melt adhesive of the present invention has a melt viscosity at 160 ° C. of preferably 12000 mPa · s or less, more preferably 2000 to 11000 mPa · s, and further preferably 4000 to 10000 mPa · s. The melt viscosity is measured by the method described in the examples.

The hot melt adhesive of the present invention is excellent in adhesiveness with various substrates including low polar substances such as polyolefins, and is excellent in thermal stability during heating and melting. It can be suitably used for bookbinding, textiles, woodworking, electrical materials, canning, construction and bag making.
Particularly, it is suitably used for adhesion of polyolefin-based materials. For example, it is used for adhesion between polyolefin nonwoven fabric and polyolefin nonwoven fabric, or adhesion between polyolefin film and polyolefin nonwoven fabric, and preferably, adhesion between PP nonwoven fabric and PP nonwoven fabric. Or used for adhesion between PE film and PP nonwoven fabric.

The method for applying the hot melt adhesive of the present invention is not particularly limited, and for example, any method of contact application or non-contact application may be used. Contact coating refers to a coating method in which an ejector is brought into contact with a member or a film when applying a hot melt adhesive. Non-contact coating refers to an ejector applied to a member or a film when applying a hot melt adhesive. The coating method which does not contact. Examples of the contact coating method include slot coater coating and roll coater coating. Non-contact coating methods include, for example, spiral coating to be applied in a spiral manner, omega coating to be applied in a wave shape, control seam coating, slot spray coating to be applied in a planar manner, curtain spray coating, and dot coating. Dot coating etc. to work are mentioned.
Among these, spiral coating is preferable for the hot melt adhesive of the present invention. Spiral coating is a method in which an adhesive is spirally contactlessly applied with air by intermittent or continuous coating.

  In the examples of the present specification, various physical properties were measured according to the following methods.

<Tensile modulus>
The sample was press-molded to prepare a test piece, and the tensile modulus (MPa) of the sample was measured under the following conditions in accordance with JIS K7113.
-Test piece (No. 2 dumbbell) Thickness: 1mm
・ Crosshead speed: 100mm / min
・ Load cell: 100N
・ Measurement temperature: 23 ℃

<Elongation at break>
A sample was press-molded to produce a test piece, and the tensile elongation at break (%) of the sample was measured under the following conditions in accordance with JIS K7113.
・ Test piece (JIS K7113-1 / 2 size dumbbell) Thickness: 1mm
・ Measurement temperature: 23 ℃
・ Tensile speed: 100 mm / min
・ Distance between chucks: 40mm

[Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn) measurement]
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the sample were determined by gel permeation chromatography (GPC). For the measurement, the following apparatus and conditions were used, and a weight average molecular weight in terms of polystyrene was obtained. The results are shown in Table 1.
<GPC measurement device>
Column: TOSO GMHHR-H (S) HT
Detector: RI detector for liquid chromatogram WATERS 150C
<Measurement conditions>
Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 1.0 ml / min Sample concentration: 2.2 mg / ml
Injection volume: 160 μl
Calibration curve: Universal Calibration
Analysis program: HT-GPC (Ver.1.0)

[Intrinsic viscosity (η)]
Viscometer (trade name: “VMR-053U-PC · F01”), Ubbelohde viscometer tube (time volume: 2-3 ml, capillary diameter: 0.44-0.48 mm) ), 0.02-0.16 g / dL solution was measured at 135 ° C. using tetralin as a solvent. The results are shown in Table 1.

[Melting point (Tm-D)]
Using a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer Co.), the sample was obtained by holding 10 mg of the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere and then raising the temperature at 10 ° C./min. The melting point (Tm-D) was determined from the peak top of the peak observed on the highest temperature side of the melting endotherm curve. The results are shown in Table 1.

[Production of resin composition for hot melt adhesive]
Components (A) to (D) are blended in the proportions (parts by mass) shown in Table 2, placed in a 1 liter stainless steel container, heated at 180 ° C. for 30 minutes with a mantle heater and melted, and then the rotor blades The hot melt adhesives of Examples 1 to 4 and Comparative Examples 1 to 4 were manufactured by sufficiently stirring. The melt viscosity and T-shaped peel adhesive strength were measured for each hot melt adhesive.

(A-1) Propylene homopolymer 1
Idemitsu Kosan Co., Ltd. product name: “L-MODU S901”
(A-2) Propylene homopolymer 2
Idemitsu Kosan Co., Ltd. product name: “L-MODU S400”
(B-1) Elastomer 1
Hydrate of styrene butadiene random copolymer, manufactured by JSR Corporation: Trade name “Dynalon 1321P” (breaking elongation 811%, tensile modulus 2.0 MPa, styrene content 10% by mass)
(B-2) Elastomer 2
Styrene Butadiene Block Copolymer Made by Kraton Polymer: Trade name “Clayton D-1102JSZ” (breaking elongation 629%, tensile modulus 22.6 MPa)
(B-3) Elastomer 3
Hydrate of styrene butadiene block copolymer, manufactured by JSR Corporation: Trade name “Dynalon 8600P” (elongation at break 684%, tensile modulus 2.3 MPa)
(C) Tackifying resin Hydrogenated alicyclic hydrocarbon resin, manufactured by ExxonMobil Chemical Co., Ltd .: trade name “Escollets 5300”
(D) Oil Paraffinic process oil Idemitsu Kosan Co., Ltd. product name: “Diana Process Oil PW-90”

[Evaluation of hot melt adhesive]
The melt viscosity was measured for each hot melt adhesive. Moreover, the bonding test piece was created in order to evaluate the adhesive performance of each hot melt adhesive, and the T-shaped peel adhesive strength was measured under the following conditions. The evaluation results are shown in Table 3.

[Melt viscosity]
Based on JIS K-6862, it measured at 160 degreeC using the Brookfield type rotational viscometer.

[Create bonded specimen]
A spiral spray gun manufactured by Nordson Co., Ltd. was set on the HMA coater system manufactured by MEC Co., Ltd., and a laminate was produced in which the coated base material to which the hot melt adhesive was applied and the bonded base material were bonded.
PP nonwoven fabric (SMS3 layer, 17 g / m ² , 150 mm width) or breathable PE film (20 g / m ² , 150 mm width) is used as the coating substrate, and PP nonwoven fabric (same as above) is used as the bonding substrate. And bonded together at a line speed of 150 m / min.
The coating conditions of the spiral spray gun (nozzle diameter: about 0.5 mmφ) were a hot melt adhesive melting temperature of 150 ° C., a spray gun temperature of 150 ° C., and a hot air temperature of 180 ° C. The amount of hot melt adhesive applied was 4 g / m ^2, and the hot air pressure was adjusted so that the width of the coated spiral was about 15 mm. The pressure for pressure bonding with a press roller after coating was 0.1 MPa, and the open time was about 0.1 seconds.
The laminate bonded with the hot-melt adhesive was cut at a width of 25 mm in the direction perpendicular to the traveling direction of the substrate (CD direction), and used as a test piece for measuring the T-shaped peel adhesive strength. The PE film-PP non-woven fabric adhesive strength test results are indicated as “PE / NW” in the table, and the PP non-woven fabric-PP non-woven fabric adhesive strength test results are indicated as “NW / NW” in the table. The test piece was cured at 23 ° C. and 50% RH for 24 hours or more, and then subjected to a T-shaped peel test in the same environment.
In order to evaluate the change in peel adhesive strength over time, test pieces cured at 23 ° C. and 50% RH for 24 hours or more are held at 50 ° C. for 2 weeks and 4 weeks, and further cured at 23 ° C. and 50% RH for 24 hours. After that, the peel adhesive strength was measured in the same manner.

[T-peeling test]
In the T-type peel test, an autograph AGS-X manufactured by Shimadzu Corporation was used, a peel test was performed at a peel speed of 100 mm / min, and a peel length of 30 mm, and an average value of two maximum values was calculated. Five test pieces were measured for each hot melt adhesive, and the average value of the top three was taken as the peel adhesive strength.

[Stability evaluation]
A: All of the following conditions are satisfied B: One of the following conditions is satisfied C: None of the following conditions is satisfied (1) Reduction rate of PE / NW adhesive strength: 20% or less Reduction rate = [( Initial peel adhesive strength)-(4 weeks aging peel adhesive strength)] / (initial peel adhesive strength)
* Data that has not declined is marked as "-" and judged to satisfy the conditions.
(2) NW / NW adhesive strength reduction rate: 10% or less Reduction rate = [(initial peel adhesive strength) − (4 weeks aging peel adhesive strength)] / (initial peel adhesive strength)
* Data that has not declined is marked as "-" and judged to satisfy the conditions.

  The hot melt adhesive of the present invention has high fluidity when melted, exhibits high adhesive strength between PP nonwoven fabrics, and further has high adhesiveness and long-term stability of PE film-PP nonwoven fabric. For this reason, it can be suitably used as a hot-melt adhesive for sanitary materials, packaging, bookbinding, textiles, woodworking, electrical materials, canning, building and bag making.

Claims (8)

(A) a propylene homopolymer satisfying the following (i) to (iii):
(B) A hot melt adhesive containing a styrene random copolymer.
(I) Tensile modulus at 23 ° C. is 400 MPa or less (ii) Weight average molecular weight (Mw) is 10,000 to 150,000
(Iii) Mw / Mn is 2.5 or less   (B) The hot melt adhesive according to claim 1, wherein the styrene random copolymer is a hydrogenated styrene copolymer.   (A) The hot melt adhesive according to claim 1 or 2, wherein the content of the propylene homopolymer is 1 to 50 parts by mass with respect to 100 parts by mass of the hot melt adhesive.   (B) The hot-melt-adhesive in any one of Claims 1-3 whose content of a styrene random copolymer is 1-50 mass parts with respect to 100 mass parts of hot-melt-adhesives.   (B) The hot melt adhesive according to any one of claims 1 to 4, wherein the styrene random copolymer is a random copolymer of an aromatic vinyl compound and a conjugated diene.   (B) The hot-melt-adhesive of Claim 5 whose content of the structural unit derived from the aromatic vinyl compound of a styrene random copolymer is 1-40 mass%.   (B) The hot-melt-adhesive of Claim 5 or 6 whose content of the structural unit derived from the conjugated diene of a styrene random copolymer is 60-99 mass%.   (B) The hot melt adhesive according to any one of claims 1 to 7, wherein the styrene random copolymer has a breaking elongation of 700% or more and a tensile elastic modulus of 10 MPa or less.