JPH10168417A - Hot melt adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot-melt adhesive exhibiting excellent low-temperature adhesiveness to a polyolefin-based material and having no fear of adversely affecting a working environment due to a pungent odor. SOLUTION: One or more base polymer components (a) selected from the group consisting of an ethylene-based copolymer, a styrene-based block copolymer and an olefin-based resin, a tackifier resin (b), and an oxidized polyolefin-based resin Excluding wax, it contains a crystalline polar group-containing compound (c) having a melting point of 40 to 170 ° C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a hot melt adhesive.

[0002]

2. Description of the Related Art Conventionally, polyolefin-based materials such as polyethylene and polypropylene are easily available and can be easily processed into films, sheets, foamed sheets, various molded products, and the like. Widely used in.

[0003] However, polyolefin materials have low surface energy and are difficult to bond with an adhesive. Therefore, bonding using an organic solvent-based adhesive having good wettability is generally performed widely. However, regulations on the use of organic solvents have become stricter, and various attempts have been made to bond with adhesives that do not use organic solvents. One of the methods is, for example, bonding with a hot melt adhesive.

[0004] Generally, a hot melt adhesive widely used includes a base polymer such as an ethylene-vinyl acetate copolymer or a styrene-based block copolymer, and a tackifying resin compatible with the base polymer. And those to which hydrocarbon waxes, oils, and the like are added as necessary. However, such a hot-melt adhesive has a problem in that the adhesiveness to a polyolefin-based material, particularly the adhesiveness at a low temperature is low, and the utility is poor.

As a solution to the above problem, for example, JP-A-59-217777 discloses that a tackifier resin and a polyolefin oxide wax are added to a styrene thermoplastic rubber such as a styrene-butadiene-styrene block copolymer. And hot melt adhesives are disclosed. However, in this hot melt adhesive, since an air oxide or a pyrolysis product of a polyolefin wax is used as the wax, an irritating odor is generated at the time of heating and melting, which may contaminate the working environment during the bonding operation.

[0006]

An object of the present invention is to exhibit excellent low-temperature adhesion to polyolefin-based materials,
Another object of the present invention is to provide a hot-melt adhesive which does not contaminate the working environment due to a pungent odor.

[0007]

The hot melt adhesive of the present invention comprises at least one base polymer component (a) selected from the group consisting of an ethylene copolymer, a styrene block copolymer and a polyolefin resin. ), A tackifying resin (b), and a crystalline polar group-containing compound (c) having a melting point of 40 to 170 ° C., excluding an oxidized polyolefin wax.

[0008] The hot melt adhesive of the present invention contains a base polymer component (a), a tackifying resin (b) and a crystalline polar group-containing compound (c).

The base polymer component (a) includes:
One or more selected from the group consisting of ethylene copolymers, styrene block copolymers, and polyolefin resins are used.

Examples of the ethylene copolymer include ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, ethylene-acrylate copolymer, and ethylene- (meth) acrylate. −
And carbon monoxide copolymer. These ethylene-based copolymers may be used alone or in combination of two or more.

The (meth) acrylate constituting the ethylene- (meth) acrylate copolymer includes, for example, methyl acrylate, ethyl acrylate,
N-propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, glycidyl acrylate, and the like. May be used alone or in combination of two or more.

Further, the ethylene- (meth) acrylate copolymer may be a copolymer obtained by copolymerizing a third component such as carbon monoxide and maleic anhydride.

The ethylene content in the ethylene copolymer is preferably 30 to 98% by weight, more preferably 4 to 98% by weight.
0 to 90% by weight.

The above-mentioned ethylene copolymer has a melt index (measured according to JIS K6730) of 10 to 10.
It is preferably 5,000 g / 10 min, more preferably 100 to 2,000 g / 10 min.

The above ethylene copolymers may be used alone or in combination of two or more. When two or more are used in combination, the melt index of the mixture falls within the above range. Is preferably selected.

The styrene block copolymer includes, for example, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, and hydrogenated products thereof.

The styrene-based block copolymers include, for example, those containing diblock copolymers such as styrene-isoprene block copolymers, styrene-butadiene block copolymers and hydrogenated products thereof. , A multi-block copolymer, a branched block copolymer, or a modified one such as maleic anhydride grafting or epoxidation.

The styrene content in the styrenic block copolymer is preferably 5 to 50% by weight, more preferably 10 to 40% by weight. The viscosity of the styrene-based block copolymer in a 25% by weight toluene solution (25 ° C.) is preferably 50 to 10,000 mPa · s, and more preferably 50 to 2,000 mPa · s.

These styrene block copolymers may be used alone or in combination of two or more. When two or more styrene block copolymers are used in combination, the styrene block copolymer may be used in combination. 25% by weight toluene solution of the mixture (25%
C) is preferably selected to fall within the above range.

Examples of the polyolefin resin include polyethylene, polypropylene, polyhexene, polyoctene, ethylene-propylene copolymer, propylene-butene copolymer, propylene-hexene copolymer,
A crystalline or non-crystalline polyolefin resin such as a propylene-octene copolymer and an ethylene-propylene-butene copolymer is exemplified.

The melt viscosity of the polyolefin resin (1)
90 ° C.) is preferably from 100 to 100,000 mPa · s, and more preferably from 1,000 to 50,000 mPa · s.
a · s. The polyolefin resin may be used alone or in combination of two or more. When two or more polyolefin resins are used in combination, the melt viscosity (190 ° C.) of the mixture is in the above range. It is preferable to select so as to enter.

The tackifying resin (b) includes rosin-based, terpene-based, petroleum resin-based and cumarone-based resins.

Examples of the above-mentioned rosin-based tackifying resin include gum rosin, wood rosin, polymerized rosin, disproportionated rosin, hydrogenated rosin, dimerized rosin; Rosin phenolic resins and the like.

As the terpene-based tackifying resin,
Examples include terpene resins, copolymers of terpene and styrene, copolymers of terpene and α-methylstyrene, copolymers of terpene and phenol, and hydrogenated products thereof.

The petroleum resin-based tackifying resin includes:
Examples include aliphatic petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, petroleum resins of aliphatic-aromatic copolymers, and hydrogenated products thereof.

Examples of the above-mentioned coumarone resin-based tackifying resin include coumarone resin, coumarone-indene resin and the like. In addition to the above, a xylene resin can be used as the tackifier resin.

The above tackifier resins may be used alone, or two or more resins having different types and different softening points may be used in combination. The tackifier resin preferably has a softening point in the ring and ball method of 30 to 160 ° C, more preferably a softening point in the ring and ball method of 60 to 120 ° C.

When the tackifying resin is liquid at normal temperature,
If used alone, the cohesive strength of the adhesive may be too low, so it is preferable to use it together with a tackifier resin that is solid at room temperature.

The crystalline polar group-containing compound (c) is selected from higher aliphatic alcohols, higher fatty acids, higher fatty amides, higher fatty acid metal salts, higher fatty acid esters and higher fatty ethers, excluding oxidized polyolefin waxes. One or more selected from the group consisting of:

As the higher aliphatic alcohol, for example, aliphatic alcohols having about 16 to 30 carbon atoms such as cetyl alcohol, stearyl alcohol, and ecosanol, and a series of "Unisan alcohol" supplied by Petrolite are provided. And higher synthetic alcohols having an average carbon number of up to about 50. These higher aliphatic alcohols may be mixtures having different carbon numbers.

The higher fatty acids include, for example, lauric acid, palmitic acid, stearic acid, hydroxystearic acid, behenic acid, arachidic acid, and purified products thereof from animal and vegetable oils containing these acids; Examples of the acid series include synthetic long-chain carboxylic acids having an average carbon number of up to about 50.

As the above higher aliphatic amide, for example,
Monoamides of higher fatty acids such as lauric acid amide, palmitic acid amide, stearic acid amide, hydroxystearic acid amide, behenic acid amide; methylenebisstearic acid amide, ethylenebisstearic acid amide, ethylenebislauric acid amide, ethylenebisoleic acid Bisamides which are reaction products of higher fatty acids such as amides with diamines; N-stearylstearic amide;
Substituted amides such as N-oleyl stearamide, n-stearyl erucamide and the like can be mentioned.

The above-mentioned metal salts of higher fatty acids are known as metal soaps, and include, for example, metal salts of the above-mentioned higher fatty acids such as barium stearate, calcium stearate, zinc stearate, aluminum stearate and magnesium stearate. Can be mentioned.

The higher fatty acid esters include, for example, mono-, di- or triesters of stearic acid, oxystearic acid, hydroxystearic acid, palmitic acid, oleic acid, linoleic acid and the like, and glycerin, sorbitan and the like; Mixtures: polyhydric alcohol esters of fatty acids such as hydrogenated castor oil and the like.

The aliphatic ethers include, for example, methoxylated products and ethoxylated products of the above-mentioned higher aliphatic alcohols. For example, long-chain alcohols supplied by Petrolite as a series of “Unitox ethoxylated alcohols” The ethoxylated product can be mentioned.

The melting point of the crystalline polar group-containing compound (c) is limited to 40 to 170 ° C., and more preferably 70 to 170 ° C.
160 ° C. When the melting point is lower than 40 ° C., the cohesive force of the hot melt adhesive decreases, and when the melting point is higher than 170 ° C., melting by heating becomes difficult.

When the base polymer component (a) is an ethylene copolymer, the proportion of the ethylene copolymer in the hot melt adhesive is preferably 20 to 80% by weight, more preferably 30 to 60% by weight. It is. If the blending ratio of the ethylene copolymer is less than 20% by weight, the low-temperature adhesiveness decreases, and if it exceeds 80% by weight, the melt viscosity becomes too high and the workability decreases.

When the base polymer component (a) is a styrene block copolymer, the mixing ratio of the styrene block copolymer in the hot melt adhesive is 10 to 5%.
0% by weight is preferable, and more preferably 20 to 40% by weight.
It is. When the blending ratio of the styrenic block copolymer is 1
If the amount is less than 0% by weight, the low-temperature adhesiveness or the high-temperature adhesiveness will be reduced.

When the base polymer component (a) is a polyolefin resin, the proportion of the polyolefin resin in the hot melt adhesive is preferably 20 to 80% by weight, more preferably 40 to 70% by weight. If the blending ratio of the polyolefin resin is less than 20% by weight,
The low-temperature adhesiveness decreases, and if it exceeds 80% by weight, the high-temperature adhesive performance decreases.

The mixing ratio of the tackifier resin (b) in the hot melt adhesive is preferably from 10 to 60% by weight, more preferably from 20 to 50% by weight. In any case where the mixing ratio of the tackifier resin (b) is less than 10% by weight or more than 60% by weight, it is difficult to develop low-temperature adhesion.

The compounding ratio of the crystalline polar group-containing compound (c) in the hot melt adhesive is preferably 0.5 to 30% by weight, more preferably 1 to 20% by weight.
In any case where the compounding ratio of the crystalline polar group-containing compound (c) is less than 0.5% by weight or more than 30% by weight, it is difficult to exhibit low-temperature adhesion.

The hot melt adhesive of the present invention uses the above-mentioned crystalline polar group-containing compound (c), so that it is not necessary to use a hydrocarbon wax which is usually used. When the solidification rate needs to be improved, a hydrocarbon wax may be used as long as the object of the present invention is not impaired.

Examples of the hydrocarbon wax include paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, and polypropylene wax. However, the use of oxidized polyolefin-based wax should be avoided in order to eliminate the risk of working environment contamination due to the pungent odor, which is the object of the present invention.

The mixing ratio of the hydrocarbon wax is 3
The content is preferably 0% by weight or less, more preferably 20% by weight or less. When the compounding ratio of the hydrocarbon wax exceeds 30% by weight, low-temperature adhesion cannot be obtained.

If necessary, a softener, a filler, an antioxidant, a coloring agent (pigment, dye), an ultraviolet absorber and the like may be added to the hot melt adhesive.

Examples of the softener include process oils such as paraffin oil, naphthene oil, and aroma oil known as rubber developing oils; plasticizers such as phthalate esters and phosphate esters; liquid polybutene;
Examples thereof include liquid polybutadiene and a hydrogenated product thereof, liquid polyisoprene and a hydrogenated product thereof, and these may be used alone or in combination of two or more.

The mixing ratio of the above softener is preferably 40% by weight or less, more preferably 30% by weight or less. When the blending ratio of the softener exceeds 40% by weight, high-temperature adhesion cannot be obtained.

Examples of the filler include calcium carbonate, clay, talc, carbon black, silica and the like. Examples of the antioxidant include known antioxidants such as hindered phenol-based, hindered amine-based, phosphorus-based, and sulfur-based antioxidants, which may be used alone or in combination of two or more. Is also good.

The production equipment for the hot melt adhesive may be any equipment having a function of heating, stirring or kneading, and the equipment conventionally used for producing a hot melt adhesive can be used as it is. . Examples of such production equipment include a single-screw or twin-screw extruder, a sigma blade mixer, a ribbon mixer, a butterfly mixer, a kneader, and the like.

As the production procedure of the hot melt adhesive, a conventional production procedure can be adopted.
It is preferably obtained by charging the components of the hot melt adhesive to the above-mentioned facility heated to 0 ° C, more preferably 140 to 200 ° C, and heating and mixing.

The hot melt adhesive may be directly supplied from the manufacturing apparatus to the coating apparatus via a heating pipe or a heating vessel. However, as in the case of the usual hot melt adhesive, the hot melt adhesive is cooled and solidified. It may be supplied in a state. Examples of the supply method in the solid state include a pellet, a bead, a strip, a stick, a sheet, a film, and a shaped article made of a hot melt adhesive alone.
In this case, it is preferable that the hot melt adhesive itself is not tacky, but if it is sticky, it is shipped with a non-sticky coating applied to the surface of the adhesive having the above shape, and is non-sticky at the time of bonding. It is used as it is with a varnished coating.

Examples of the non-adhesive coating include thin coatings of silicone oil, wax, lubricant, etc .; polyethylene, amorphous polypropylene,
Coating with a film of an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, or the like can be given.

When the hot melt adhesive has tackiness, it may be subjected to a non-tacky treatment which can be removed at the time of use. Examples of such a non-adhesive treatment include, for example, a state of being wrapped with release-treated paper or a plastic film; and a state of being filled in a container made of release-treated paper or a plastic film. Examples of the material that can be directly melted in a container include a metal can and a metal or paper drum that is supplied in a state of being filled.

Using the hot melt adhesive of the present invention,
Examples of a method for bonding polyolefin-based materials to each other or a polyolefin-based material and another material include the following methods (1) to (3).

(1) A method in which an adhesive in a heat-melted state is applied to one material, and the other material is bonded before the adhesive solidifies: (a) The adhesive is heated and melted by an applicator. A method of applying dots, beads, spirals, and planes through nozzles and slits, (b) a method of melting an adhesive on a heating roll and applying it by a roll, (c) extrusion using an extruder Coating methods and the like can be mentioned.

(2) A method of applying an adhesive in a heat-melted state to one material, cooling it once, and then bonding the other material: (a) A method of reheating and melting the adhesive at the time of bonding (B) a method in which the adhesive is sticky when the adhesive has tackiness; and (c) a method in which the adhesive surface of a material to which the adhesive is not applied is heated to a temperature higher than the softening point of the adhesive and then bonded. . As a method of reheating, a hot plate, hot air, a method of heating the adhesive or material with infrared heating, or the like,
A method of causing the adhesive or the material to generate heat by electromagnetic wave induction heating or the like may be used.

(3) A method in which an adhesive formed in a sheet or film shape is inserted between both materials and bonded by means such as a hot press. Further, when applying the adhesive, carbon dioxide gas and nitrogen gas are used. May be mixed and foamed.

When the hot-hot melt adhesive of the present invention is used, pretreatment such as surface treatment and preheating for the polyolefin material is not necessarily required, but preheating, corona discharge treatment, plasma treatment, ultraviolet irradiation, By applying a surface treatment such as acid etching, sand blasting, polishing treatment, or silane coupling agent treatment, or a pretreatment such as coating an adhesion enhancer such as a primer on the surface, even better adhesion can be obtained. Becomes

Examples of the polyolefin-based material include films, sheets, foamed sheets, non-woven fabrics, and molded articles of polyethylene, polypropylene and the like. Further, these polyolefin-based materials and other materials may be laminated by an adhesive, heat fusion, or coextrusion, or may be a polyolefin-based material coated with another material.

The other materials include, for example, paper; iron,
Metal materials including aluminum, nickel, tin, lead and alloys thereof; ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyester, polyvinyl chloride, polystyrene, polycarbonate, acrylonitrile-butadiene-styrene copolymer, polyurethane, acrylic resin And the like; films, sheets, molded articles, and the like of ceramic materials including glass.

Applications to which the hot melt adhesive of the present invention can be applied include, in addition to assembling and sealing paper containers such as cardboard and cartons, automobile parts, electric / electronic parts, sanitary articles, books, magazines, and the like. .

[0062]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Examples 1 to 4, Comparative Examples 1 and 2) Preparation of Hot Melt Adhesive The base polymer component (a), tackifier resin (b), and crystalline polar group-containing at the amounts shown in Table 1 A hot melt adhesive was prepared by melt-mixing the compound (c) or the wax and the antioxidant at 180 ° C.

Measurement of Peeling Strength of Hot Melt Adhesive The hot melt adhesives obtained in the above Examples and Comparative Examples were subjected to a 180 ° peel test, and the results are shown in Table 1. A hot melt adhesive heated to 180 ° C. was applied to a 2 mm thick polypropylene plate in a single bead at an application amount of about 3 g / m, and after about 2 seconds, a 40 μm thick polypropylene film was stuck and tested. Pieces were made. Then, using an "Autograph AG-10TB" manufactured by Shimadzu Corporation, at a different temperature of 0 ° C. and 10 ° C., a 180 ° peel test in a direction perpendicular to the direction of the bead (pulling speed 300 m
m / min), and the peak strength was taken as the peel strength.

[0065]

[Table 1]

The components used in the above table are shown below. (1) Base polymer (a): DuPont-Mitsui Polychemical Co., Ltd., ethylene-ethyl acrylate copolymer “Evaflex A-715”, ethyl acrylate content 25
% By weight, melt index = 800 g / 10 min (2) Tackifying resin (b): Arakawa Chemical Industries, Ltd., hydrogenated rosin ester resin "Ester gum H" softening point 75 ° C

(3) Crystalline polar group-containing compound (c): C-1: manufactured by Nippon Kasei Co., Ltd.
"Diamid 200" Melting point 103 ° C ・ C-2: Nippon Kasei Co., Ltd., methylene bisstearic acid amide, “Diamid 200 Bisamide LA”, Melting point 143 ° C ・ C-3: Petrolite, long chain ethoxylated alcohol , "Unitox 750", average carbon number about 50, melting point 106 ° C

(4) Hydrocarbon wax: Fischer-Tropsch wax “Sazol wax H1” manufactured by Sasol Corporation (South Africa), melting point 105 ° C. (5) Antioxidant hindered phenol “Irganox 1010” manufactured by Ciba Geigy

As is evident from Table 1, the hot melt adhesives of the examples have remarkably higher low-temperature adhesiveness, particularly the peel strength at 0 ° C., than the hot melt adhesives of the comparative examples.

[0070]

The hot-melt adhesive of the present invention has the above-described structure, exhibits excellent low-temperature adhesion to polyolefin-based materials, and uses no oxidized polyolefin-based wax. No irritating odor is generated. Accordingly, the hot melt adhesive of the present invention is useful for assembling and sealing paper containers such as corrugated cardboard and cartons; especially in the fields of automobile parts, electric / electronic parts, sanitary articles, books, magazines, etc. It is suitably used for bonding a material to another material.

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Claims (2)

[Claims] 1. An at least one base polymer component (a) selected from the group consisting of an ethylene copolymer, a styrene block copolymer and a polyolefin resin, a tackifier resin (b), and an oxidized polyolefin. A hot melt adhesive comprising a crystalline polar group-containing compound (c) having a melting point of 40 to 170 ° C, excluding a system wax. 2. A crystalline polar group-containing compound (c) having a melting point of 40 to 170 ° C., comprising a higher aliphatic alcohol, a higher fatty acid,
1 selected from the group consisting of higher aliphatic amides, higher fatty acid metal salts, higher fatty acid esters and higher aliphatic ethers
2. The hot melt adhesive according to claim 1, which is at least one kind.