CN109790437B

CN109790437B - Hot melt adhesive

Info

Publication number: CN109790437B
Application number: CN201780056837.XA
Authority: CN
Inventors: 佐见津麻希
Original assignee: Moresco Corp
Current assignee: Moresco Corp
Priority date: 2016-10-18
Filing date: 2017-08-29
Publication date: 2021-07-20
Anticipated expiration: 2037-08-29
Also published as: CN109790437A; JPWO2018074070A1; WO2018074070A1; JP6795608B2

Abstract

One aspect of the present invention relates to a hot melt adhesive comprising: a thermoplastic polymer, a tackifier, and a softener, wherein the softener comprises an acid-modified oil that is modified with at least one of a carboxylic acid and a carboxylic acid anhydride.

Description

Hot melt adhesive

Technical Field

The present invention relates to a hot melt adhesive.

Background

The hot melt adhesive is applied to an adherend that is an object to be bonded in a state of being melted by heating, and the adherend is held in contact with each other by the molten hot melt adhesive, thereby bonding the adherend to each other. Such hot melt adhesives are used, for example, in the packaging field of corrugated paper, cartons and the like; the field of sanitary materials such as paper diapers and menstrual products; and various fields such as a binding field, a plywood field, a woodworking field, an automobile field, a home appliance field, and a housing field.

Further, the hot melt adhesive is used in a state of being melted by heating as described above, and thus a solvent is not particularly required. Therefore, the hot melt adhesive is preferably used as an adhesive having high safety to the human body, for example, in the field of sanitary materials. Specifically, in disposable sanitary materials such as disposable diapers and catamenial products, hot melt adhesives are widely used for fixing and assembling components thereof.

When a hot melt adhesive is used in the field of such sanitary materials, the hot melt adhesive is frequently in contact with moisture such as body fluid due to its use. Among hot melt adhesives, adhesives whose adhesiveness is reduced when they are brought into contact with water, that is, adhesives whose adhesiveness is reduced in a wet state, are known. In the field where there are many opportunities for contact with moisture, such a hot melt adhesive may not maintain the adhesion between the components during use of the product, and the product itself may break. Therefore, the hot melt adhesive is required to maintain adhesiveness in a wet state.

Examples of the pressure-sensitive adhesive for the purpose of improving the adhesiveness in such a wet state include the pressure-sensitive adhesives described in patent documents 1 to 4.

Patent document 1 describes a hot melt adhesive comprising: a thermoplastic block copolymer which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound; and waxes modified with carboxylic acids and/or carboxylic acid anhydrides. Patent document 1 discloses the following: the wet adhesion is improved, and at least 1 selected from the group consisting of low-temperature adhesion, viscosity, adhesion, odor, and economy is further improved.

Further, patent document 2 describes a hot melt adhesive for disposable products, which contains: a propylene homopolymer having a melting point of 100 ℃ or lower obtained by polymerizing propylene using a metallocene catalyst; and waxes modified with carboxylic acids and/or carboxylic acid anhydrides. Patent document 2 discloses the following: is suitable for high-speed coating, and has excellent adhesion in a wet state and low-temperature coating.

Further, patent document 3 describes a hot melt adhesive comprising: an acid-modified thermoplastic block copolymer; an adhesive property imparting resin; a plasticizing oil; and wax. Patent document 3 discloses the following: has excellent adhesiveness and exhibits excellent adhesiveness from immediately after adhesion to after long-term storage regardless of whether the adherend is in a dry state or a wet state.

Further, patent document 4 describes a hot melt adhesive comprising: a thermoplastic block copolymer containing at least one of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a hydrogenated product thereof; and an acid-modified petroleum resin acid-modified with an unsaturated carboxylic acid or an acid anhydride thereof. Patent document 4 discloses the following: the moisture-bondability to the constituent member is improved without causing a decrease in thermal stability or odor.

In the bonding method using a hot melt adhesive, first, a hot melt adhesive melted by heating is applied to an adherend by an applicator or the like. The coated hot melt adhesive is held in contact with another adherend, whereby the adherends can be bonded to each other.

Further, in the field of sanitary materials such as paper diapers, improvement of texture is demanded. Therefore, attempts have been made to improve the texture by increasing the flexibility of a disposable diaper or the like by thinning the constituent material of the adherend using a hot melt adhesive. However, when the constituent material is thinned, heat resistance tends to be lowered. When a hot melt adhesive melted by heating is applied to such a constituent material having low heat resistance, the constituent material may be melted or deformed, that is, damaged. The constituent material tends to be thermally damaged as follows: this occurs significantly when the temperature of the hot melt adhesive applied increases or the amount of hot melt adhesive applied increases. Therefore, in order to use such a component material having low heat resistance, low-temperature application and low-volume application of a hot melt adhesive are required in the field of sanitary materials. Specifically, what is required is: even if the amount of the hot melt adhesive to be applied is reduced by lowering the temperature at which the hot melt adhesive is melted, reducing the nozzle diameter of the applicator, or the like, sufficient adhesion between the adherend can be ensured.

In the case of such low-temperature coating and small-amount coating, there is a tendency that: the heat quantity of the hot melt adhesive during application is reduced, and the hot melt adhesive is difficult to penetrate into an adherend, and the adhesive strength is difficult to be improved, and particularly the wet adhesive strength is difficult to be improved. In addition, a hot melt adhesive having a high viscosity and poor coatability cannot be suitably coated. Therefore, the hot melt adhesive is also required to have excellent coatability.

Among the hot melt adhesives, there are also the following types: the hot melt adhesive is insufficient in adhesiveness under low temperature conditions, and poor adhesion may sometimes occur in winter or in cold environments. In order to be used in winter and in cold environments, a hot melt adhesive is also required to have excellent adhesion under low temperature conditions.

Therefore, the hot melt adhesive is required to have not only excellent adhesiveness in a wet state but also excellent coatability and adhesiveness under low temperature conditions.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2007-169531

Patent document 2: japanese patent laid-open publication No. 2013-64054

Patent document 3: japanese laid-open patent publication No. 2005-104996

Patent document 4: japanese patent laid-open publication No. 2015-91917

Disclosure of Invention

The invention aims to provide a hot melt adhesive which has excellent adhesiveness in a wet state, coating property and adhesiveness under a low temperature condition.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description.

Detailed Description

The present inventors have found that, in the hot melt adhesive, although the adhesive properties in a wet state can be improved by the adhesive described in patent documents 1 to 4, the following problems may occur in the case of low-temperature application, small-amount application, and the like.

For example, when a wax modified with a carboxylic acid and/or a carboxylic acid anhydride is contained as described in patent documents 1 and 2, poor compatibility may occur, and the coatability may be lowered.

Further, as described in patent documents 3 and 4, when a thermoplastic polymer or a tackifier contained in a hot melt adhesive is acid-modified, the hot melt adhesive may have a decreased coating property due to an increase in viscosity or poor compatibility. Further, when such a hot melt adhesive is used, the adhesiveness under low temperature conditions is insufficient, and poor adhesion may be caused in winter or in cold environments.

The present inventors have conducted various studies and as a result, have found that the following invention can achieve the above object of providing a hot melt adhesive excellent in adhesiveness in a wet state, coatability and adhesiveness under low temperature conditions.

The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

The hot melt adhesive of an embodiment of the present invention comprises: thermoplastic polymers, tackifiers, and softeners. And, the softening agent comprises: an acid-modified oil modified with at least one of a carboxylic acid and a carboxylic acid anhydride. The hot melt adhesive is not particularly limited as long as it contains a thermoplastic polymer, a tackifier, and a softener, and the softener contains an acid-modified oil modified with at least one of a carboxylic acid and a carboxylic anhydride. The hot melt adhesive contains the acid-modified oil, whereby the adhesiveness in a wet state is improved while maintaining the performance, for example, adhesiveness, which can be exhibited by a general hot melt adhesive, and further, the coatability and the adhesiveness under low temperature conditions can be improved. The hot melt adhesive means the following adhesives: the adhesive composition is solid (solid) at normal temperature, has fluidity by heating, can be applied to an adherend as an object to be adhered, and can be solidified by cooling after application, thereby adhering the adherend to each other.

First, the thermoplastic polymer used in the present embodiment is not particularly limited as long as it is a thermoplastic polymer used as a component constituting the hot melt adhesive. The thermoplastic polymer may be a thermoplastic polymer used as a base polymer which is a main component of a hot melt adhesive. Specific examples of the thermoplastic polymer include: an elastomer, an olefin, an ethylene-vinyl acetate copolymer (EVA) based thermoplastic polymer, a polyester based thermoplastic polymer, a polyamide based thermoplastic polymer, or a polyacrylic acid based thermoplastic polymer. Among these, in the present embodiment, the thermoplastic polymer of the elastomer system and the thermoplastic polymer of the olefin system are preferable, and the thermoplastic polymer of the elastomer system is more preferable.

The thermoplastic polymer of the elastic system is not particularly limited as long as it is a thermoplastic polymer used as the thermoplastic polymer of the elastic system in the hot melt adhesive, and examples thereof include: a conjugated diene polymer that is a polymer having a constituent unit (conjugated diene unit) based on a conjugated diene compound, and the like. In addition, as the thermoplastic polymer of the elastic system, specifically, there can be mentioned: and copolymers of conjugated diene compounds and vinyl aromatic hydrocarbons, i.e., thermoplastic block copolymers. That is, as the thermoplastic polymer, these thermoplastic block copolymers are preferably used.

The conjugated diene compound is not particularly limited as long as it is a diene compound having at least one pair of conjugated double bonds. Specific examples of the conjugated diene compound include: 1, 3-butadiene, 2-methyl-1, 3-butadiene (isoprene), 2, 3-dimethyl-1, 3-butadiene, 1, 3-pentadiene, 1, 3-hexadiene, and the like.

The vinyl aromatic hydrocarbon is not particularly limited as long as it is an aromatic hydrocarbon having a vinyl group. Specific examples of the vinyl aromatic hydrocarbon include: styrene, o-methylstyrene, p-tert-butylstyrene, 1, 3-dimethylstyrene, alpha-methylstyrene, vinylnaphthalene, vinylanthracene, and the like.

The conjugated diene polymer may be a hydrogenated conjugated diene copolymer or a non-hydrogenated conjugated diene copolymer which is not hydrogenated.

The thermoplastic polymer is preferably the thermoplastic block copolymer, and specific examples thereof include: styrene-butadiene block copolymers, styrene-isoprene block copolymers, hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-isoprene block copolymers, and the like. In addition, these copolymers comprise ABA type triblock copolymers. Examples of the styrene-butadiene block copolymer include: styrene-butadiene-styrene block copolymers (SBS), and the like. Examples of the styrene-isoprene block copolymer include: styrene-isoprene-styrene block copolymers (SIS), and the like. Examples of the hydrogenated styrene-butadiene block copolymer include: styrene-ethylene-butylene-styrene block copolymer (SEBS), and the like. Examples of the hydrogenated styrene-isoprene block copolymer include: styrene-ethylene-propylene-styrene block copolymers (SEPS), and the like.

In addition, when the thermoplastic block copolymer is used, the thermoplastic polymer exhibits excellent adhesiveness, tackiness, and the like, but the adhesiveness in a wet state may be lowered depending on the material of an adherend and the like. The hot melt adhesive of the present embodiment can maintain other properties and improve the adhesiveness in a wet state, and therefore can maintain excellent adhesiveness, tackiness, and the like of the thermoplastic block copolymer and improve the adhesiveness in a wet state. Therefore, as the thermoplastic polymer, the thermoplastic block copolymer is preferably used.

The olefinic thermoplastic polymer is not particularly limited as long as it is a thermoplastic polymer used as the olefinic thermoplastic polymer in the hot melt adhesive. Examples of the olefinic thermoplastic polymer include: polyolefin compounds which are solid at ordinary temperature and polymerized in the presence of a Ziegler-Natta catalyst or a single-site catalyst, and the like. Specific examples of the olefinic thermoplastic polymer include: polyethylene, polypropylene, poly-1-butene, polyisobutylene, a random copolymer or block copolymer of propylene and at least one of ethylene and 1-butene in an arbitrary ratio, an ethylene-propylene-diene terpolymer containing a diene component in an arbitrary ratio of ethylene and propylene, a random copolymer or block copolymer of ethylene or propylene and a vinyl compound, random polypropylene, block polypropylene, homopolypropylene, an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, an ethylene-1-octene copolymer, a propylene-ethylene-1-butene copolymer, a 1-butene homopolymer, a 1-butene-ethylene copolymer, a 1-butene-propylene copolymer, a propylene-ethylene copolymer, a propylene-1-butene copolymer, a propylene-ethylene copolymer, a propylene-1-butene copolymer, a propylene-ethylene copolymer, a propylene copolymer, a copolymer, propylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, and the like. As the olefinic thermoplastic polymer, for example, among the above exemplified compounds, olefinic polymers obtained by polymerizing an olefin (olefin) such as α -olefin as a monomer are preferable. Specific examples of the olefin polymer include poly α -olefin polymers. More specifically, amorphous-polyalphaolefin polymers (APAO), homopolymers of propylene (propylene homopolymers), and the like are preferable as the polyalphaolefin polymers. More specifically, a propylene homopolymer obtained by polymerizing propylene using a metallocene catalyst, and the like are preferable.

The EVA-based thermoplastic polymer is not particularly limited as long as it is a thermoplastic polymer used as the EVA-based thermoplastic polymer in the hot melt adhesive, and examples thereof include: copolymers synthesized from ethylene and vinyl acetate, and the like.

The polyester-based thermoplastic polymer is not particularly limited as long as it is a thermoplastic polymer used as a polyester-based thermoplastic polymer in the hot melt adhesive. Examples of the polyester-based thermoplastic polymer include: polyesters polymerized using dimer acids as monomers, and the like.

The polyamide-based thermoplastic polymer is not particularly limited as long as it is a thermoplastic polymer used as a polyamide-based thermoplastic polymer in a hot melt adhesive, and examples thereof include: polyamides, and the like.

The polyacrylic acid-based thermoplastic polymer is not particularly limited as long as it is a thermoplastic polymer used as a polyacrylic acid-based thermoplastic polymer in the hot melt adhesive, and examples thereof include: polyacrylates, polymethacrylates, and the like.

The thermoplastic polymer may be used alone or in combination of two or more.

The weight average molecular weight of the thermoplastic polymer varies depending on the kind of the thermoplastic polymer, and is not particularly limited, but is, for example, preferably 1 to 50 ten thousand, and more preferably 5 to 30 ten thousand. If the molecular weight of the thermoplastic polymer is too small, the cohesive force tends to decrease and the stability with time tends to decrease. Further, if the molecular weight of the thermoplastic polymer is too large, the melt viscosity tends to increase and the coatability tends to decrease. The weight average molecular weight herein is not particularly limited as long as it is a weight average molecular weight measured by a general measurement method, and examples thereof include a weight average molecular weight measured by Gel Permeation Chromatography (GPC).

The tackifier used in the present embodiment is not particularly limited as long as it is a tackifier generally used in a hot melt adhesive. Examples of the tackifier include: rosin-based resins, terpene-based resins, petroleum-based resins, and the like.

Examples of the rosin-based resin include: gum rosin, tall oil rosin, wood rosin and other natural rosins; disproportionated rosin, polymerized rosin, glycerol or pentaerythritol esters of these rosins, and the like. The rosin-based resin may be the respective rosin-based resins described above which are not hydrogenated, or may be hydrogenated rosin-based resins, that is, hydrogenated products (hydrogenated products) of the rosin-based resins described above.

Examples of the terpene-based resin include: terpene resins, hydrocarbon-modified terpene resins, aromatic-modified terpene resins, and phenol-modified terpene resins. The terpene-based resin may be the above-mentioned terpene-based resin without being hydrogenated, or may be hydrogenated product (hydrogenated product) of the above-mentioned terpene-based resin after being hydrogenated. The terpene resin is preferably an aromatic modified terpene resin hydrogenated product, an aromatic modified terpene resin, or a terpene resin hydrogenated product, and more preferably an aromatic modified terpene resin hydrogenated product.

Examples of the petroleum resin include: aliphatic petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, and hydrogenated products (hydrogenated products) thereof.

Further, as the hydrogenated petroleum resin, hydrogenated aliphatic petroleum resin, hydrogenated alicyclic petroleum resin, and hydrogenated aromatic petroleum resin are preferable. Examples of the hydrogenated alicyclic petroleum resin include: hydrogenated C9 petroleum resins, hydrogenated dicyclopentadiene petroleum resins, and the like.

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

The softener used in the present embodiment is not particularly limited as long as it is a softener containing an acid-modified oil modified with at least one of a carboxylic acid and a carboxylic acid anhydride.

The acid-modified oil is not particularly limited as long as it is an acid-modified oil obtained by modifying an oil that can be used as a softening agent in the hot melt adhesive with at least one of a carboxylic acid and a carboxylic acid anhydride. Examples of the acid-modified oil include: an acid-modified oil obtained by adding an oil to at least one of a carboxylic acid and a carboxylic acid anhydride; an acid-modified oil or the like synthesized by adding at least one of a carboxylic acid and a carboxylic acid anhydride to a raw material having an olefin skeleton such as an α -olefin by an ene-reaction (ene-reaction).

The softener before acid modification is not particularly limited as long as it can be used as a softener in a hot melt adhesive. Examples of the softening agent include oil and the like. The oil is a liquid that is liquid at normal temperature and pressure, and examples thereof include a liquid substance having no melting point. Examples of the oil include liquid hydrocarbons having no melting point. Examples of the softener before the acid modification, that is, the oil before the modification include: mineral oils, synthetic oils, vegetable oils, fatty acid esters, and the like.

Specific examples of the mineral oils include process oils and liquid paraffin. The process oil is an oil generally used as a plasticizer for rubber, thermoplastic elastomer, or the like, and is an oil produced in so-called petroleum refining or the like. The process oil is a mixture generally containing an aromatic ring, a naphthenic ring, or a paraffinic chain, and is roughly classified into a paraffinic process oil, a naphthenic process oil, and an aromatic process oil. In the process oil, those having a paraffin chain carbon number of 50% or more of the total carbon number are classified into paraffinic ones, those having a naphthene ring carbon number of 30% or more are classified into naphthenic ones, and those having an aromatic carbon number of 30% or more are classified into aromatic ones. The paraffin process oil includes a C4-155 paraffin compound, and preferably a C4-50 paraffin compound. Specific examples of the paraffinic process oil include: n-paraffins such as butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, docosane, tricosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane, nonacosane, triacontane, hentriacontane, dotriacontane, pentadecane, sixty and heptadecane; isoparaffins such as isobutane, isopentane, neopentane, isohexane, isopentane, neohexane, 2, 3-dimethylbutane, various methylhexanes, 3-ethylpentane, various dimethylpentanes, 2, 3-trimethylbutane, 3-methylheptane, various dimethylhexanes, various trimethylpentanes, isononane, 2-methylnonane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane, isooctadecane, isonnonadecane, isoeicosane, and 4-ethyl-5-methyloctane; derivatives of these saturated hydrocarbons, and the like. These selected paraffin compounds may be used in the form of a mixture, and are liquid at room temperature.

Specific examples of the synthetic oils include phosphate esters, chlorinated paraffins, ethylene- α -olefin oligomers, polybutenes, low molecular weight polybutadienes, polyisoprenes, hydrogenated products thereof, and the like, which are liquid at room temperature.

Specific examples of the vegetable oils include: olive oil, carnauba wax, rice germ oil, corn oil, camellia oil, castor oil, jojoba seed oil, eucalyptus leaf oil, and the like.

Specific examples of the fatty acid esters include: isopropyl myristate, octyldodecyl myristate (octyldodecyl myristate), triisocaprylic glyceride, diisopropyl adipate, diethyl sebacate, cetyl ethylhexanoate, cetyl palmitate, ethylhexyl palmitate, isopropyl palmitate, medium-chain fatty acid triglyceride, ethylene glycol salicylate, ethylene glycol distearate, and the like.

As the softener before the acid modification, that is, the oil before the modification, paraffin-based oil such as liquid paraffin, naphthene-based oil, aromatic-based oil, and the like are preferable among the exemplified oils. The above-mentioned oil may be used alone or in combination of two or more kinds thereof as the softener before modification.

The pour point of the oil before modification is preferably-30 ℃ or higher. In addition, the kinematic viscosity of the oil before modification is preferably 5-5000 mm²In seconds. When the kinematic viscosity is too small, the possibility of the heat resistance being reduced is high; when the kneading temperature is increased, there is a risk of ignition. If the kinematic viscosity is too high, the melt viscosity of the hot melt may increase, and the coatability may decrease. The ignition point of the oil before modification is preferably 150 ℃ or higher, preferably 200 ℃ or higher, and more preferably 250 ℃ or higher.

The carboxylic acid used for the acid modification is not particularly limited. Examples of the carboxylic acid used for the acid modification include: maleic acid, fumaric acid, succinic acid, phthalic acid, glutaric acid, itaconic acid, acrylic acid, methacrylic acid, and the like.

The carboxylic anhydride used for the acid modification is not particularly limited. Examples of the carboxylic anhydride used for the acid modification include: maleic anhydride (anhydride of maleic acid), succinic anhydride, phthalic anhydride, glutaric anhydride, and the like.

The carboxylic acid is preferably maleic acid, fumaric acid, or acrylic acid, and more preferably maleic acid. The carboxylic anhydride is preferably maleic anhydride. Further, maleic anhydride as a carboxylic acid anhydride is preferable as the substance used for the acid modification.

The carboxylic acid and the carboxylic anhydride may be used alone or in combination of two or more.

Examples of the acid-modified oil include: an acid-modified oil obtained by modifying the oil before modification with at least one of the carboxylic acid and the carboxylic anhydride. Examples of the acid-modified oil include: an oil having a succinic acid skeleton in the molecule, and the like.

The method for producing the acid-modified oil is not particularly limited as long as the acid-modified oil modified with at least one of a carboxylic acid and a carboxylic acid anhydride can be produced. Specific examples of the method for producing the acid-modified oil include: a method of adding at least one of a carboxylic acid and a carboxylic acid anhydride to a raw material oil to perform an addition reaction, and the like. In carrying out this addition reaction, a radical initiator may be used. Further, examples of the method for producing the acid-modified oil include: a method of heating and melting at least one of an oil, a radical initiator, and a carboxylic acid anhydride, which are raw materials, and mixing them to perform an addition reaction. In this case, the temperature during melt mixing may be, for example, 160 to 200 ℃. The apparatus for carrying out the method is not particularly limited as long as it is an apparatus capable of reacting the oil raw material with at least one of the carboxylic acid and the carboxylic anhydride. Examples of such a device include: a melting reaction tank filled with an inert gas and having a stirring function.

The radical initiator used in the addition reaction is not particularly limited as long as the addition reaction can proceed, and can be appropriately selected from known radical initiators. Examples of the radical initiator include organic peroxide compounds. Examples of the organic peroxide compound include: di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, dilauroyl peroxide, cumyl hydroperoxide, t-butyl hydroperoxide, 1-di-t-butylperoxy-3, 3, 5-trimethylcyclohexane, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, 1-di-t-butylperoxy cyclohexane, cyclohexanone peroxide, t-butyl peroxybenzoate, t-butyl peroxyisobutyrate, t-butyl peroxy-3, 5, 5-trimethylhexanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisopropylcarboxylate, and cumyl peroxyoctoate. Among them, dicumyl peroxide is preferable.

The amount of the radical initiator to be added is not particularly limited as long as the addition reaction can be appropriately performed. The amount of the radical initiator added is preferably 1 to 50% by mass, more preferably 10 to 30% by mass, based on the total mass of the carboxylic acid and the carboxylic anhydride. When the amount of the radical initiator added is within the above range, the addition reaction to the main chain can be performed while suppressing the low molecular weight of the acid-modified oil.

The softening agent used in the present embodiment may contain the acid-modified oil as described above. That is, the softener may be formed from the acid-modified oil. The softening agent may contain not only the acid-modified oil but also a softening agent other than the acid-modified oil. The softening agent other than the acid-modified oil is not particularly limited as long as it is contained in the hot melt adhesive. Specific examples of the softening agent other than the acid-modified oil include the same ones as the oil before the acid modification.

The content of the acid-modified oil is not particularly limited as long as it is within a range that does not inhibit the desired properties targeted by the present invention. Specifically, the content of the acid-modified oil is preferably 0.02 to 100 parts by mass, more preferably 0.03 to 70 parts by mass, and still more preferably 1 to 55 parts by mass, based on 100 parts by mass of the softener. When the content of the acid-modified oil is too small, the effect of containing the acid-modified oil cannot be sufficiently exhibited, and the adhesiveness in a wet state tends to be insufficiently improved. The softening agent may be composed of the acid-modified oil as described above, but when the content of the acid-modified oil is too large, the adhesiveness may be reduced due to a decrease in low-temperature adhesiveness or insufficient cohesive force.

In the hot melt adhesive, the respective contents of the thermoplastic polymer, the tackifier and the softening agent are not particularly limited as long as the contents do not inhibit the desired properties targeted by the present invention. The contents are, for example, in the following ranges.

The content of the thermoplastic polymer is preferably 10 to 75% by mass, more preferably 15 to 65% by mass, and still more preferably 15 to 30% by mass, based on the hot melt adhesive. That is, the content of the thermoplastic polymer is preferably 10 to 75 parts by mass with respect to 100 parts by mass of the hot melt adhesive. When the content of the thermoplastic polymer is too small, the cohesive force tends to be insufficient. When the content of the thermoplastic polymer is too large, the melt viscosity increases, and the coatability tends to decrease.

The content of the tackifier is preferably 20 to 80 mass%, more preferably 35 to 70 mass%, and further preferably 40 to 70 mass% with respect to the hot melt adhesive. That is, the content of the tackifier is preferably 20 to 80 parts by mass with respect to 100 parts by mass of the hot melt adhesive. When the content of the thickener is too small, the adhesive strength tends to be reduced due to the reduction in adhesive force. When the content of the thickener is too large, the flexibility or flexibility is lost, and the stress dispersibility is lowered, so that the holding power tends to be lowered.

The content of the softening agent is preferably 5 to 40% by mass, more preferably 10 to 25% by mass, and still more preferably 15 to 25% by mass, based on the hot melt adhesive. That is, the content of the softening agent is preferably 5 to 40 parts by mass with respect to 100 parts by mass of the hot melt adhesive. When the content of the softening agent is too small, the melt viscosity increases, and the applicability tends to decrease. When the content of the softening agent is too large, the cohesive force tends to be lowered, and the adhesive force or holding force tends to be lowered.

The hot melt adhesive of the present embodiment may contain additives other than the thermoplastic polymer, the tackifier, and the softening agent within a range that does not inhibit the desired characteristics as an object of the present invention. Specifically, the additives include additives such as an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a filler, a surfactant, a coupling agent, a colorant, an electricity inhibitor, a flame retardant, a wax, and a plasticizer. The hot melt adhesive is solid at ordinary temperature, and may contain a solvent, but preferably does not contain a solvent. The hot melt adhesive is preferably composed of the thermoplastic polymer, the tackifier, the softener, and the additive, for example.

Examples of the antioxidant include: phenol antioxidants, organic sulfur antioxidants, phosphorus antioxidants, and the like. Examples of the phenolic antioxidant include: 2, 6-di-tert-butyl-4-methylphenol, n-octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, tetrakis (methylene-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate) methane, and the like. Examples of the organic sulfur-based antioxidant include: dilauryl-3, 3 ' -thiodipropionate, dimyristyl-3, 3 ' -thiodipropionate, distearyl-3, 3 ' -thiodipropionate, pentaerythritol tetrakis (3-laurylthiopropionate), and the like. Examples of the phosphorus antioxidant include: tris (nonylphenyl) phosphite, tris (2, 4-di-t-butylphenyl) phosphite, and the like. These antioxidants may be used alone or in combination of two or more.

The wax is not particularly limited as long as it is contained in the hot melt adhesive. Examples of the wax include: synthetic waxes, petroleum waxes, and natural waxes. Examples of the synthetic wax include: polyolefin waxes such as fischer-tropsch wax, polyethylene wax, and polypropylene wax. Examples of the petroleum wax include: paraffin, microcrystalline wax, petrolatum, and the like. Examples of the natural wax include: montan wax, wood wax, carnauba wax, beeswax, and castor wax. These waxes may be used alone or in combination of two or more.

The method for producing the hot melt adhesive of the present embodiment is not particularly limited as long as it is a production method capable of producing the hot melt adhesive having the above-described configuration. Examples of the method for producing the hot melt adhesive include: a method of heating and melting the components constituting the hot melt adhesive, and kneading the molten components. Thus, a hot melt adhesive having high dispersibility of components constituting the hot melt adhesive can be obtained. Further, as an apparatus for realizing this method, for example: a stirring and kneading machine, a roll machine, a banbury mixer, a kneader, an extruder, and the like, each of which is provided with a heating device.

The method of adhesion using a hot melt adhesive is not particularly limited as long as it can be used as an adhesion method using a hot melt adhesive. As an adhesion method using a hot melt adhesive, for example, the hot melt adhesive is melted by heating. Then, the hot melt adhesive in a molten state is applied to an adherend as an object to be bonded. The other adherend is placed in contact with the coated hot melt adhesive, whereby the hot melt adhesive is cooled and solidified. The solidified hot melt adhesive bonds adherends to each other.

The method of applying the hot melt adhesive is not particularly limited as long as it is suitable for applying the hot melt adhesive to an adherend. The coating method can be roughly classified into a contact coating method and a non-contact coating method, for example. The contact coating method is a coating method in which a hot melt adhesive is applied in a state where an apparatus for coating such as a coater is brought into contact with an adherend. The non-contact coating method is a coating method in which a hot melt adhesive is applied in a state where the hot melt adhesive is not brought into contact with an adherend by a coater or the like. Examples of the contact coating method include: slit coating (spray gun manufactured by Noxin corporation, etc.) and roll coating method. Further, examples of the non-contact coating method include: spiral coating (spiral nozzle manufactured by shoile corporation) capable of spiral coating, spray coating (omega coater manufactured by kuita natter corporation) capable of wave coating, spray coating (curtain nozzle manufactured by shoile corporation) capable of planar coating, dot coating capable of dot coating, and the like. The hot melt adhesive of the present embodiment is suitable for spiral coating. The spiral coating is a method of coating the adhesive in a spiral shape by a batch coating or a continuous coating in a non-contact coating method and using a gas.

The present specification discloses the techniques of the various embodiments as described above, and the main techniques thereof are summarized as follows.

According to this configuration, a hot melt adhesive excellent in adhesiveness in a wet state, coatability and adhesiveness under low temperature conditions can be provided.

Further, in the hot melt adhesive, it is preferable that: the carboxylic acid is maleic acid and the carboxylic anhydride is maleic anhydride.

According to this configuration, a hot melt adhesive having more excellent adhesiveness in a wet state, coatability, and adhesiveness under low temperature conditions can be provided.

Further, in the hot melt adhesive, it is preferable that: the acid-modified oil is an oil having a succinic acid skeleton in the molecule.

Further, in the hot melt adhesive, it is preferable that: the content of the acid-modified oil is 0.02 to 100 parts by mass relative to 100 parts by mass of the softener.

Further, in the hot melt adhesive, it is preferable that: the oil before modification in the acid-modified oil is at least 1 selected from the group consisting of paraffin-based oils, naphthene-based oils, and aromatic-based oils.

Further, in the hot melt adhesive, it is preferable that: the thermoplastic polymer is a copolymer of a conjugated diene compound and a vinyl aromatic hydrocarbon or an olefin polymer.

The thermoplastic polymer is a hot melt adhesive comprising a copolymer of a conjugated diene compound and a vinyl aromatic hydrocarbon or an olefin polymer, and exhibits excellent adhesiveness and tackiness, but the adhesiveness in a wet state may decrease depending on the material of an adherend or the like. The hot melt adhesive according to an embodiment of the present invention, which is a hot melt adhesive containing the acid-modified oil, has excellent adhesiveness in a wet state even when the thermoplastic polymer contains the copolymer or the olefin-based polymer. Therefore, according to the above configuration, a hot melt adhesive excellent in coatability and adhesiveness under low temperature conditions, and further excellent in adhesiveness in a wet state can be provided.

Further, in the hot melt adhesive, it is preferable that: the copolymer is at least 1 selected from the group consisting of a styrene-butadiene block copolymer, a styrene-isoprene block copolymer, a hydrogenated styrene-butadiene block copolymer, and a hydrogenated styrene-isoprene block copolymer.

According to this constitution, a hot melt adhesive excellent in adhesiveness in a wet state and further excellent in coatability and adhesiveness under low temperature conditions can be provided.

Further, in the hot melt adhesive, it is preferable that: the olefin polymer is a poly-alpha-olefin polymer.

According to the present invention, a hot melt adhesive excellent in adhesiveness in a wet state, coatability and adhesiveness under low temperature conditions can be provided.

The present invention will be further specifically described below with reference to examples, but the scope of the present invention is not limited thereto.

Examples

First, the respective components used in the production of the hot melt adhesive in the present example will be described.

[ thermoplastic Polymer ]

Thermoplastic polymer 1: styrene-butadiene-styrene Block copolymer (SBS) (Asaprene T-439 manufactured by Asahi Kasei Co., Ltd.)

Thermoplastic polymer 2: styrene-butadiene-styrene Block copolymer (SBS) (Asaprene T-420 manufactured by Asahi Kasei K.K.)

Thermoplastic polymer 3: propylene homopolymer (L-MODU X400S available from Shikino corporation)

Thermoplastic polymer 4: propylene homopolymer (L-MODU X600S available from Shikino corporation)

Thermoplastic polymer 5: amorphous-polyalphaolefin Polymer (APAO) (VESTOPLAST 704 available from EVONIK corporation)

Acid-modified thermoplastic polymer: maleic acid-modified styrene-ethylene-butylene-styrene Block copolymer (maleic acid-modified SEBS) (Tuftec M1913, manufactured by Asahi Kasei Co., Ltd.)

[ tackifier ]

Tackifier 1: hydrogenated aromatic modified terpene resin (hydrogenated aromatic modified terpene resin) (Clearon K-4100 manufactured by Anyuan chemical Co., Ltd.)

Tackifier 2: hydrogenated alicyclic Petroleum resin (hydrogenated C9 Petroleum resin) (Alcon M-100, Daihuan chemical Co., Ltd.)

Tackifier 3: hydrogenated alicyclic Petroleum resin (hydrogenated C9 Petroleum resin) (Alcon P-100, Daihuan chemical Co., Ltd.)

Tackifier 4: hydrogenated alicyclic Petroleum resin (hydrogenated dicyclopentadiene Petroleum resin) (Escorez 5320, manufactured by Exxon Mobil Co., Ltd.)

[ softening agent ]

Oil: oil (Diana Fresia S32 manufactured by Shikino corporation)

Acid-modified oil 1: maleic acid-modified oil (oil having a succinic acid skeleton in the molecule) (AS-1532 available from Astro light PMC Co., Ltd.)

Acid-modified oil 2: maleic acid modified oil (oil having a succinic acid skeleton in the molecule) (SIZEPINE SA-864 manufactured by Mitsuwa chemical industries, Ltd.)

Acid-modified wax: maleic acid-modified wax (wax having a succinic acid skeleton in the molecule) (Licocene PPMA6252 manufactured by Nippon Kabushiki Kaisha)

Acid-modified rubber: maleic acid-modified liquid rubber (liquid rubber having a succinic acid skeleton in the molecule) (Kuraprene LIR-410, a product of Lely, Ltd.)

[ additives ]

Antioxidant: irganox 1010 manufactured by BASF corporation

[ method for producing Hot-melt adhesive ]

The above components were kneaded in the following steps so as to be blended amounts (components: parts by mass) shown in table 1 below, to prepare a hot melt adhesive. The tackifier, the softener and the additive are added to a stirring mixer, and the mixture is stirred in a state of being heated to 150-190 ℃ so as to be fully melted. The thermoplastic polymer is added to the melt and kneaded while being heated to 150 to 190 ℃, whereby the thermoplastic polymer is sufficiently melted and uniformly dispersed in the melt. Then, the acid-modified tackifier was added to the melt, and the mixture was kneaded with stirring. In this case, the mixture is kneaded as much as possible until the hot melt adhesive has high uniformity. By doing so, a hot melt adhesive is produced.

[ evaluation ]

(coating Property: melt viscosity)

The melt viscosity of the hot melt adhesive before curing at 140 ℃ was measured in accordance with the following procedure. Specifically, the viscosity of a melt of the hot melt adhesive melted at 140 ℃ was measured with a Brookfield viscometer (spindle No. 27) according to the measurement method described in JIS K6682. This viscosity is the melt viscosity at 140 ℃ of the hot melt adhesive before curing.

In addition, the melt viscosity of the hot melt adhesive before curing at 160 ℃ was measured by the same method.

(adhesion under Low temperature conditions: Low temperature adhesive Strength)

The produced hot melt adhesive was coated on a polyethylene terephthalate (PET) film having a thickness of 50 μm to form a 50 μm thick film, and the film was molded to have a width of 25mm in the direction (MD) parallel to the running direction of the substrate. On the PET film having the hot melt adhesive formed on the surface thereof, a Polyethylene (PE) film is provided in contact with the hot melt adhesive. Then, the PET film and the PE film were stuck to each other at a speed of 300 mm/min by a 2kg roll and then left at room temperature for 24 hours. The product in the adhered state was used as a test piece. Then, 3 of the test pieces were prepared for each of the respective hot melt adhesives. Then, the test piece was peeled at a speed of 300 mm/min under an atmosphere of 10 ℃ and the strength at that time was measured. The intensity was measured for 3 test subjects, and the average of the 3 measured values was calculated. The average value was defined as low-temperature adhesive strength, and the adhesive properties under low-temperature conditions were evaluated using this strength. The low-temperature adhesive strength was evaluated as "very excellent" when it was 15N/25mm or more, as "good" when it was 10N/25mm or more and less than 15N/25mm, and as "poor" when it was less than 10N/25 mm.

(adhesiveness in Wet State: Wet adhesive Strength)

After the produced hot melt adhesive was melted by heating to 150 ℃, the molten hot melt adhesive was applied to a spiral nozzle at a density of 5gsm (g/m)²) Is coated on one surface of the nonwoven fabric. After 1 second from the application, a paper towel was placed on the hot-melt adhesive-applied nonwoven fabric so as to contact the hot-melt adhesive. Then, the mixture was heated at 23 ℃ under a pressure of 50gf/cm²The nonwoven and tissue were pressed for 0.01 second. The laminate was cut at 25mm intervals in the direction perpendicular to the travel direction (CD) of the base material, to prepare a long test piece. Then, the test piece was immersed in tap water at 23 ℃ for 5 to 6 seconds, and then taken out of the water and wiped off to prepare a test body in a wet state. Then, 3 of the test pieces were prepared for each of the respective hot melt adhesives. Then, the test piece was subjected to a T-peel test based on JIS K6845. Specifically, the strength of the test piece when peeled at a tensile rate of 100 mm/min was measured. The peel test was performed at 23 ℃ and 65% RH.

As a result of the peeling test, the case where the tissue was entirely broken was evaluated as "excellent", the case where the tissue was partially broken was evaluated as "o", and the case where the tissue was not broken was evaluated as "x".

(compatibility)

The hot melt adhesive produced was visually confirmed to be in a state of being melted by heating at 160 ℃. When white turbidity was not observed, the evaluation was "o", and when white turbidity was observed, the evaluation was "x".

The evaluation results are shown in table 1 together with the blending amount of the hot melt adhesive.

TABLE 1

As can be seen from Table 1: in the case where the hot melt adhesive contains a thermoplastic polymer, a tackifier, and a softening agent, and the softening agent contains an acid-modified oil modified with maleic acid (examples 1 to 7), the adhesiveness under low temperature conditions, the adhesiveness in a wet state, and the compatibility are excellent as compared with other cases (comparative examples 1 to 5). In addition, it can be seen that: examples 1 to 7 contain the acid-modified oil, but they are excellent in compatibility and also excellent in coating properties because of the above-mentioned melt viscosity.

The hot melt adhesives of examples 1 to 7 had higher wet adhesion strength than those without the softener modified with maleic acid (comparative examples 1 and 5). The hot melt adhesives of comparative examples 1 and 5 do not contain a softening agent modified with maleic acid, and therefore, a problem in compatibility does not occur easily, but wet adhesive strength cannot be improved.

Further, in the case of containing the wax modified with maleic acid (comparative example 2) and the case of containing the liquid rubber modified with maleic acid (comparative example 4), the compatibility was deteriorated. In addition, in the case of containing a thermoplastic polymer modified with maleic acid (comparative example 3), compatibility was reduced and low-temperature adhesive strength could not be improved.

From these results, it can be seen that: by containing a softening agent modified with maleic acid, a hot melt adhesive excellent in coatability and sufficiently high in low-temperature adhesive strength and wet adhesive strength can be obtained.

In example 1, the acid-denatured oil was contained by about 0.16 part by mass with respect to 100 parts by mass of the softener. In example 2, about 5.26 parts by mass of the acid-denatured oil was contained per 100 parts by mass of the softener. From a comparison of example 1 with example 2, it can be seen that: the content of the acid-modified oil is preferably 0.3 parts by mass or more per 100 parts by mass of the softener. In example 4, about 21.74 parts by mass of the acid-denatured oil was contained per 100 parts by mass of the softener. In example 5, about 55.56 parts by mass of the acid-denatured oil was contained per 100 parts by mass of the softener. From a comparison of example 4 and example 5, it can be seen that: the content of the acid-modified oil is preferably 55 parts by mass or less with respect to 100 parts by mass of the softener.

The present application is based on Japanese patent application No. 2016-.

The present invention has been described in detail with reference to the above embodiments in order to describe the present invention, but it should be understood that modifications and/or improvements can be easily made to the above embodiments by those skilled in the art. Therefore, the modified embodiments or modified embodiments that can be implemented by those skilled in the art are intended to be included in the scope of the claims as long as they do not depart from the scope of the claims set forth in the claims.

Industrial applicability

Claims

1. A hot melt adhesive characterized by comprising:

a thermoplastic polymer, a tackifier and a softener, wherein,

the softening agent comprises:

an acid-modified oil modified with at least one of a carboxylic acid and a carboxylic anhydride, and

a softening agent other than the acid-modified oil;

the content of the acid-modified oil is 0.03 to 55 parts by mass relative to 100 parts by mass of the total amount of the softener.

2. A hot melt adhesive as set forth in claim 1, wherein:

the carboxylic acid is a maleic acid, and the carboxylic acid is,

the carboxylic anhydride is maleic anhydride.

3. A hot melt adhesive as set forth in claim 1, wherein:

the acid-modified oil is an oil having a succinic acid skeleton in the molecule.

4. A hot melt adhesive as set forth in claim 1, wherein:

the oil before modification in the acid-modified oil is at least 1 selected from the group consisting of paraffin-based oils, naphthene-based oils, and aromatic-based oils.

5. A hot melt adhesive as set forth in claim 2, wherein:

6. A hot melt adhesive as claimed in claim 3, wherein:

7. A hot melt adhesive according to any one of claims 1 to 6, wherein:

the thermoplastic polymer is a copolymer of a conjugated diene compound and a vinyl aromatic hydrocarbon or an olefin polymer.

8. A hot melt adhesive as claimed in claim 7, wherein:

the copolymer is at least 1 selected from the group consisting of a styrene-butadiene block copolymer, a styrene-isoprene block copolymer, a hydrogenated styrene-butadiene block copolymer, and a hydrogenated styrene-isoprene block copolymer.

9. A hot melt adhesive as claimed in claim 7, wherein:

the olefin polymer is a poly-alpha-olefin polymer.