JPH101655A - Hot-melt adhesive and bonding of polyolefin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hot-melt adhesive comprising an ethylene-based copolymer and a tackifying resin, free from any styrene-based copolymer, having a specific range of shear storage modulus, and causing no lowering of its melt viscosity and no deterioration of its coatability even after heated for a long time. SOLUTION: This hot-melt adhesive, which is suitable for bonding polyolefin materials, comprises an ethylene-based copolymer such as an ethylene-vinyl acetate copolymer and a tackifying resin such as a coumaron resin or coumaron- indene resin, contains no styrene-based copolymer, and has the shear storage modulus of the adhesive sheet made thereof of 1×10<6> to 5×10<7> Pa determined at 0 deg.C and a frequency of 14Hz using a shear viscoelastic spectrometer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hot melt adhesive and a method for bonding a polyolefin material.

[0002]

2. Description of the Related Art Polyolefin materials such as polyethylene and polypropylene are widely available in various industrial fields because they are easily available, and are easily processed into films, sheets, foam sheets, and various molded products. Widely used. However, it is also known that bonding with an adhesive is difficult because polyolefin materials have low surface energy, and bonding using an organic solvent-based adhesive having good wettability is widely performed.

However, regulations on organic solvents are becoming stricter from the viewpoint of impact on the environment and health,
There is a demand for a bonding method using an adhesive that does not use an organic solvent. As one of the methods, various attempts have been made to bond with a hot melt adhesive. However, a hot-melt adhesive containing an ethylene copolymer as a base polymer, which is generally widely used, has a problem that adhesion to a polyolefin material is poor.

As a solution to the above problem, for example, Japanese Patent Application Laid-Open No. 62-7776 discloses a method in which an ethylene-based copolymer and a styrene-based block copolymer are used in combination, and a tackifier resin and a wax are further contained. A hot melt adhesive is disclosed. However, in the composition comprising the ethylene-based copolymer, the tackifier resin and the wax, since all components are melted by heating, the stirring at the time of production may be moderate, but when a block rubber is used as the styrene-based block copolymer, Since melting does not occur unless a shearing force is applied, equipment that can apply a high shearing force during production is required. Further, when the styrene-based block copolymer is an SIS block copolymer, the melt viscosity decreases due to molecular cutting of the SIS copolymer due to long-term heating, which results in a change in coating properties and an increase in adhesive performance. There was a problem of change.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and an object of the present invention is to provide an excellent adhesive performance to a polyolefin material without using a styrene-based block copolymer. An object of the present invention is to provide a hot-melt adhesive to be exhibited and a method for bonding a polyolefin material using the hot-melt adhesive.

[0006]

The hot melt adhesive of the invention according to claim 1 (hereinafter referred to as the first invention) comprises an ethylene copolymer and a tackifying resin and does not contain a styrene copolymer. A hot melt adhesive, wherein the adhesive sheet has a shear storage modulus of 1 × 10 ^{6 to} 5 × 10 ⁷ Pa measured by a viscoelastic spectrometer by a shear method at 0 ° C. and a frequency of 14 Hz. The above-mentioned object is achieved.

A method for bonding a polyolefin material according to the invention of claim 2 (hereinafter referred to as the second invention) is characterized in that the hot melt adhesive according to claim 1 is used when bonding the polyolefin material. Thereby, the above object is achieved.

[0008] The hot melt adhesive sheet of the first invention,
Shear storage modulus at 0 ° C. and 14 Hz frequency is 1 ×
It is 10 < ⁶ > -5 * 10 < ⁷ > Pa. 1 × shear storage modulus
When the pressure is less than 10 ⁶ Pa, the cohesive force of the adhesive is insufficient and the adhesive strength is not developed. When the pressure exceeds 5 × 10 ⁷ Pa, the adhesive is easily peeled off from the surface of the adherend and the adhesive strength is not developed. It can be easily peeled off by such means.

The above-mentioned shear storage modulus is a value represented as G 'by viscoelastic spectrum measurement. The actual measurement was performed at 0 ° C using a viscoelastic spectrometer,
Using the G 'values measured at the respective frequencies of 1, 2, 4, 7, 10, 20, and 40 Hz, a regression calculation was performed based on the following equation to calculate the G' value at a frequency of 14 Hz. log (G ′ _f ) = a ^* log (f) ³ + b ^* log (f) ² +
c ^* log (f) + d where f is the frequency and G ' _f is the G at the frequency f
^'The values a, b, c and d are constants.

[0010] The hot melt adhesive of the first invention comprises an ethylene copolymer and a tackifier resin and does not contain a styrene copolymer. As the ethylene copolymer,
For example, an ethylene-vinyl acetate copolymer, an ethylene-acrylate copolymer, an ethylene-acrylate-carbon monoxide copolymer, and the like can be given.

Examples of the acrylate include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, and acrylic acid 2
-Hydroxyethyl and the like, which may be used alone or in combination of two or more.

The ethylene content of the ethylene copolymer is preferably 30 to 98% by weight, more preferably 5 to 98% by weight.
0 to 90% by weight. The melt index in the ethylene copolymer is preferably from 10 to 5,000 dg / min, more preferably from 100 to 2,000 dg / min, as measured by JIS K6730. Two or more ethylene copolymers may be used in combination, and when two or more ethylene copolymers are used in combination, it is preferable that the melt index be selected so as to fall within the above range.

Examples of the tackifying resin include rosin-based, terpene-based, petroleum resin-based and cumarone-based resins. Examples of the rosin-based tackifying resin include gum rosin, wood rosin, polymerized rosin, disproportionated rosin, hydrogenated rosin, dimerized rosin; esters of the various rosins with pentaerythritol, glycerin, diethylene glycol and the like; rosin phenol resins and the like. Is exemplified.

The terpene-based tackifying resin includes:
Examples thereof include a terpene resin, a copolymer of terpene and styrene, a copolymer of terpene and α-methylstyrene, a copolymer of terpene and phenol, and hydrogenated products thereof.

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

Examples of the coumarone resin-based tackifying resin include coumarone resin and coumarone-indene resin. In addition to the above, a xylene resin or the like is used as the tackifier resin. The tackifying resin may be used alone, or two or more kinds having different types and softening points may be used in combination.

The tackifier resin preferably has a softening point of the ring and ball method of 30 to 160 ° C., more preferably 60 to 120 ° C. of the ring and ball method. Further, a liquid that is liquid at ordinary temperature is not preferable when used alone because the cohesive force of the adhesive is too low, but it can be used in combination with a solid that is ordinary at normal temperature.

A wax may be added to the hot melt adhesive of the first invention, if necessary. Wax is
It is used when it is necessary to lower the viscosity and improve the solidification rate.

Examples of such waxes include paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and oxidized wax obtained by oxidatively decomposing these waxes; maleic acid, maleic anhydride, fumaric acid; An acid-modified wax to which an unsaturated (anhydride) carboxylic acid such as an acid, acrylic acid, and methacrylic acid is grafted is exemplified.

In the hot melt adhesive of the first invention,
The mixing ratio of the ethylene copolymer, the tackifier resin and the wax is as follows.

The mixing ratio of the ethylene copolymer is 30 to 8
0% by weight is preferable, and more preferably 40 to 60% by weight.
It is. If it is less than 30% by weight, it is difficult to keep the shear storage modulus within the range described in claim 1, and if it exceeds 80% by weight, the melt viscosity becomes too high and the workability deteriorates.

The compounding ratio of the tackifier resin is preferably from 10 to 60% by weight, more preferably from 20 to 50% by weight. If it is less than 10% by weight, sufficient adhesiveness is not exhibited, and
If it exceeds 0% by weight, it becomes difficult to keep the shear storage modulus within the range described in claim 1.

The compounding ratio of the wax is preferably at most 40% by weight, more preferably at most 30% by weight. If it exceeds 40% by weight, it is difficult to keep the shear storage modulus within the range described in claim 1.

If necessary, a softener, a filler, an antioxidant, a colorant (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 oils, naphthene oils, and aroma oils known as rubber developing oils; plasticizers such as phthalate esters and phosphate esters; liquid polybutene, liquid polybutadiene, and water thereof. Additives, liquid polyisoprene and its hydrogenated products,
A liquid adhesive resin such as a liquid rosin resin and a liquid terpene resin may be used. These may be used alone,
More than one species may be used in combination. However, it is preferable to select the shear storage modulus so as to fall within the range described in claim 1.

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, and these may be used alone or in combination of two or more. .

The hot melt adhesive manufacturing equipment may be any equipment having a function of heating, stirring or kneading, and the equipment conventionally used for manufacturing hot melt adhesives 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 a production procedure of the hot melt adhesive, a conventional production procedure can be adopted.
It is obtained by putting the above-mentioned hot melt adhesive constituent component into the above-mentioned equipment heated to -250 ° C, preferably 140-200 ° C, and heating and mixing.

The hot melt adhesive may be supplied from the manufacturing apparatus as it is to the coating apparatus via a heating pipe or a heating vessel. However, the hot melt adhesive is cooled and solidified, as is usually the case with the hot melt adhesive. May be supplied. Examples of the supply method in a solid state include a molded product made of an adhesive alone, such as a pellet, a bead, a strip, a stick, a sheet, a film, and a lump. In this case, it is preferable that the adhesive itself has no tackiness.

When the surface of the adhesive is tacky, the surface of the adhesive is coated with a non-adhesive material and supplied as a molded product in the form of pellets, beads, strips, sticks, sheets, films, lumps and the like. At the time of bonding, this non-tacky coating is used as it is.
Examples of the non-stick coating include a thin layer coating of silicone oil, wax, lubricant, etc .; coating with a film of polyethylene, amorphous polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. Is mentioned.

When the adhesive has tackiness, it may be subjected to a non-tacky treatment which can be removed. Examples of such a state include a state wrapped in a release-treated paper or plastic film; and a state filled in a container made of release-released paper or plastic. Supplied in such a manner that it can be directly melted in a container, it is supplied in a state of being filled in a metal can, a metal or paper drum.

Next, the second invention will be described. In the bonding method of the second invention, the polyolefin material is bonded using the hot melt adhesive of the first invention.

As a method for bonding the above-mentioned polyolefin materials to each other, or between the polyolefin material and another material by using the above-mentioned hot melt adhesive, the following methods can be mentioned. (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 with a hot melt applicator; Point, bead, spiral, or surface application through a nozzle or slit, (b) a method in which an adhesive is melted on a heating roll and roll applied, and (c) extrusion coating using an extruder Method and the like.

(2) A method in which an adhesive in a heat-melted state is applied to one material, cooled once, and then bonded to the other material: (a) A method in which the adhesive is reheated and melted when bonding (B) a method in which the adhesive is directly adhered 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. . Examples of the method of reheating include a method of heating the adhesive or the material with a hot plate, hot air, infrared rays, or the like, and a method of heating the adhesive or the material by electromagnetic wave induction heating or the like.

(3) A method in which an adhesive formed into a sheet or film is inserted between both materials and bonded by means such as a hot press.

Further, when applying the adhesive, carbon dioxide gas, nitrogen gas or the like may be mixed and applied in a foamed state.

Examples of the polyolefin material include films, sheets, foamed sheets, nonwoven fabrics, and molded products of polyethylene, polypropylene, and the like. In addition, these polyolefin materials and other materials are glued, heat-sealed,
It may be laminated by co-extrusion, or may be a polyolefin material coated with another material.

The other materials include, for example, paper; iron,
Metal materials including aluminum, nickel, tin, lead and alloys thereof; synthetic resins such as ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyester, polyvinyl chloride; films of ceramic materials including glass;
Sheets, molded products, and the like are included.

The hot melt adhesive of the present invention includes assembling and sealing of paper containers such as cardboard and cartons; automobile parts, electric / electronic parts, sanitary articles, books, magazines and the like.

[0039]

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 and 2, Comparative Examples 1 to 3) The ethylene copolymer, tackifying resin, wax and antioxidant in the amounts shown in Table 1 were melt-mixed at 180 ° C. A hot melt adhesive was prepared.

The above-mentioned hot melt adhesives were evaluated for the following properties, and the results are shown in Table 1. (I) Shear storage modulus “Viscoelastic spectrometer VES-FI” manufactured by Iwamoto Seisakusho
II "was used as a test piece, and the shear storage modulus (G ' _f ) at 0 ° C. and each frequency was measured using a sheet-shaped 2 mm thick hot melt adhesive as a test piece. Measurement conditions: shear method, frequency dispersion, measurement temperature: 0 ° C. Measurement frequency: 1, 2, 4, 7, 10, 20, 40 Hz Using G ′ _f values measured at each of the above frequencies, based on the following equation Perform a regression calculation and calculate G ^'at a frequency of 14 Hz.
Values were calculated. log (G ′ _f ) = a ^* log (f) ³ + b ^* log (f) ² +
c ^* log (f) + d where f is the frequency and G ' _f is the G at the frequency f
^'The values a, b, c and d are constants.

(II) Measurement of Peeling Strength A hot melt adhesive heated to 180 ° C. was applied to a 2 mm-thick polypropylene sheet in a single bead at an application amount of about 3 g / m. Were bonded together to prepare a test piece. Then, using an "Autograph AG-10TB" manufactured by Shimadzu Corporation, at a pulling speed of 300 mm / min.
A peel test was performed, and the peak strength was defined as the peel strength.

(III) Melt Viscosity Ratio According to JIS K6862, the melt viscosity was measured immediately after the adhesive was prepared.
180 ° C after standing in an oven at 80 ° C for 24 hours
Was measured, and the melt viscosity ratio was calculated based on the following equation. Melt viscosity ratio = melt viscosity after standing at 180 ° C / melt viscosity immediately after preparation

[0044]

[Table 1]

The components used in the table are as follows. [Ethylene copolymer]-Ethylene-ethyl acrylate copolymer: "Evaflex A-715" manufactured by DuPont-Mitsui Polychemicals Inc. Ethyl acrylate content = 25% by weight Melt index = 800 dg / min-SIS copolymer : “Clayton TR1” manufactured by Shell Chemical Company
107] [Tackifying resin] ・ Rosin ester resin (A): Arakawa Chemical Co., Ltd. “Ester Gum H”, softening point 75 ° C. ・ Rosin ester resin (B): Arakawa Chemical Co., “Super Ester A-115”, softening 115 ° C. ・ Fischer-Tropsch wax: “Sazol wax H1” manufactured by Sasol Corporation (South Africa), melting point 105 ° C. ・ Paraffin wax: “Paraffin wax 135′F” manufactured by Nippon Seiro, melting point 56 ° C. [Antioxidant] Ciba Geigy "Irganox 1010", a hindered phenolic antioxidant

[0046]

The hot melt adhesive according to the first invention has an SI
Even without using a block rubber such as S copolymer, by using an ethylene-based copolymer as a base polymer and limiting the shear storage modulus of the adhesive to a certain range, the polyolefin material can be improved. Can be glued. In addition, since block rubber such as SIS copolymer is not used, no special equipment for applying high shear is required during production, and melting by molecular cutting of SIS copolymer by prolonged heating. There are no problems such as a decrease in viscosity, a change in coatability, and a change in adhesive performance.

In the method for bonding a polyolefin material according to the second invention, the polyolefin material can be satisfactorily bonded by the conventional bonding method using the hot melt adhesive of the first invention. It is applicable to assembling and sealing of paper containers, assembling of automobile parts, electric and electronic parts, and the like.

Claims (2)

[Claims] 1. A hot melt adhesive comprising an ethylene copolymer and a tackifying resin and containing no styrene copolymer, which is measured at a frequency of 0 ° C. and 14 Hz by a viscoelastic spectrometer based on a shearing method. The adhesive sheet has a shear storage modulus of 1 × 10 ^{6 to} 5 × 10 ^7.
A hot melt adhesive characterized by being Pa. 2. A method for bonding a polyolefin material, comprising using the hot melt adhesive according to claim 1 when bonding the polyolefin material.