JP2004002689A - Hot melt adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot melt adhesive which does not increase the cost due to the use of general-purpose raw materials, excels in adhesion to various adherends, simultaneously has both excellent heat resistance and excellent low-temperature properties, and exhibits excellent adhesive performance over a broad temperature range. <P>SOLUTION: The hot melt adhesive has each compatibilized component in the melt state and has a micro phase separation structure (matrix-domain structure) in the solidified state. The hot melt adhesive has a domain area of 1.5×10<SP>2</SP>to 4.0×10<SP>6</SP>nm<SP>2</SP>in the planar section obtained from the hot melt adhesive. The hot melt adhesive comprises an ethylene copolymer, a tackifying resin, and a wax, and has the above ethylene copolymer and tackifying resin which are compatibilized in the solidified state, and simultaneously has a micro phase separation structure formed of a matrix of the above compatibilized two components and a domain of the above wax. <P>COPYRIGHT: (C)2004,JPO

Description

【００７４】
表１から明らかなように、本発明による実施例１〜実施例３のホットメルト接着剤は、いずれも優れた耐熱クリープ性および優れた耐寒接着性を発現した。
【００７５】
これに対し、固化状態においてミクロ相分離構造を有していなかった比較例１〜比較例３のホットメルト接着剤は、いずれも耐寒接着性は優れていたものの、耐熱クリープ性が極端に悪かった。
【００７６】
【発明の効果】
以上述べたように、本発明のホットメルト接着剤は、各種被着体に対する接着性に優れ、かつ、優れた耐熱性と優れた耐寒性とを兼備し、広い温度領域にわたって優れた接着性能を発現するとともに、汎用の原材料を用いるのでコストアップを来すこともないものであり、例えば、製本、包装、木工等の各種工業用途むけホットメルト接着剤として好適に用いられる。
【図面の簡単な説明】
【図１】固化状態において、ミクロ相分離構造を有している本発明（実施例１）のホットメルト接着剤を示す電子顕微鏡写真である。
【図２】固化状態において、完全相溶系であり、ミクロ相分離構造を有していない従来（比較例１）のホットメルト接着剤を示す電子顕微鏡写真である。
【図３】耐熱クリープ性の評価方法を示す斜視図である。
【図４】耐寒接着性の評価方法を示す斜視図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to hot melt adhesives.
[0002]
[Prior art]
Hot-melt adhesives are solvent-free and have the advantages of the bonding process and economical capability of being able to perform instant bonding and high-speed bonding.Therefore, they are used in large quantities mainly in the fields of bookbinding, packaging, woodworking, etc. ing. As a main component (base polymer) of the hot melt adhesive, ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer are excellent in balance of adhesiveness, flexibility, heating stability, price and the like. Is widely used. The hot melt adhesive is obtained by adding a tackifying resin as a tackiness improving agent and a wax as a function modifier to these main components.
[0003]
Among the above components, the main component is one that expresses cohesive force for imparting bulk characteristics to the hot melt adhesive, and is tough and resistant to tensile stress and compressive stress. In addition, the tackifier resin has a function of imparting wettability, permeation, tack (tackiness) and the like to the adherend to the hot melt adhesive, thereby improving the tackiness. As the tackifying resin, for example, a modified product of rosin or terpene, or an oligomer such as a petroleum resin is used. Since these tackifying resins are generally amorphous and have a higher glass transition temperature (Tg) than the main component, they also have a function of improving the heat resistance of the hot melt adhesive. Further, the wax has a function of lowering the melt viscosity of the hot melt adhesive to improve coatability and imparting quick solidification to the hot melt adhesive to enable high-speed bonding. In order to effectively exhibit the functions of the above components, it is preferable that these three components are compatible in a molten state.
[0004]
As such a hot melt adhesive, for example, a hot melt adhesive containing an ethylene-based copolymer, a wax, and a specific tackifying resin is disclosed (see Patent Document 1).
[0005]
The hot melt adhesive disclosed in the above publication is intended to improve heat resistance by using a specific tackifying resin having a high Tg, and although it is certainly excellent in heat resistance, On the other hand, there is a problem that the cold resistance is poor.
[0006]
In addition, a hot-melt adhesive using an ethylene-vinyl acetate copolymer whose Tg is increased by lowering the vinyl acetate content to increase crystallinity as a main component has excellent heat resistance, but has low cold resistance. Is the same problem as above.
[0007]
Further, Fischer-Tropsch wax having a tackifying resin of 50 to 200 parts by weight, a melting point of 80 to 95 ° C. and a molecular weight distribution (Mw / Mn) of 1.10 or less based on 100 parts by weight of the ethylene copolymer. A hot melt adhesive containing 2 to 100 parts by weight is disclosed (see Patent Document 2), and 50 to 200 parts by weight of a tackifying resin and oil based on 100 parts by weight of an ethylene copolymer. A hot melt adhesive containing 20 to 100 parts by weight of a purified paraffin wax having a content of less than 0.2% by weight is disclosed (see Patent Document 3).
[0008]
According to the above prior art, in order to impart excellent heat resistance and excellent cold resistance to a hot melt adhesive, it is necessary to purify the wax such that the melting point, molecular weight distribution, oil content, etc. of the wax are in a specific range. Therefore, there are problems that the process becomes complicated, the yield of the purified wax is reduced, and the cost is increased.
[0009]
[Patent Document 1]
JP-A-2-55783
[Patent Document 2]
JP-A-11-323286
[Patent Document 3]
JP 2000-204336 A
[0010]
[Problems to be solved by the invention]
In view of the above problems, the object of the present invention is to use a general-purpose raw material, so that cost does not increase, and it has excellent adhesiveness to various adherends, and excellent heat resistance and excellent cold resistance. Another object of the present invention is to provide a hot-melt adhesive which exhibits excellent adhesive performance over a wide temperature range.
[0011]
[Means for Solving the Problems]
The hot melt adhesive according to the first aspect of the present invention is characterized in that the components are compatible in a molten state and have a microphase separated structure (matrix-domain structure) in a solidified state. I do.
[0012]
The hot-melt adhesive according to the second aspect of the present invention is the hot-melt adhesive according to the first aspect, wherein a plane section obtained from the hot-melt adhesive has a domain area of 1.5 × 10 5 ² ~ 4.0 × 10 ⁶ nm ² And at least 25% by weight of the blending amount of the domain-forming component forms a domain.
[0013]
The hot melt adhesive according to the third aspect of the present invention is the hot melt adhesive according to the first or second aspect, wherein the domain area is 5 × 10 5. ² ~ 4.0 × 10 ⁶ nm ² It is characterized by being.
[0014]
A hot-melt adhesive according to a fourth aspect of the present invention is the hot-melt adhesive according to any one of the first to third aspects, wherein the hot-melt adhesive mainly comprises an ethylene-based copolymer.
[0015]
The hot melt adhesive according to the invention according to claim 5 is the hot melt adhesive according to any one of claims 1 to 4, wherein the hot melt adhesive contains an ethylene-based copolymer, a tackifying resin, and a wax. In the solidified state, the ethylene-based copolymer and the tackifying resin are compatible with each other, and are formed of the compatible two-component matrix and the domain of the wax. It has a micro phase separation structure.
[0016]
The hot melt adhesive according to the invention of claim 6 is the hot melt adhesive of claim 4 or 5, wherein the ethylene-based copolymer is an ethylene-vinyl acetate copolymer. I do.
[0017]
The hot melt adhesive according to the invention of claim 7 is the hot melt adhesive of claim 6, wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of 30 to 40% by weight. It is characterized.
[0018]
In the hot melt adhesive of the present invention, it is necessary that the components are compatible in a molten state and have a microphase separation structure (matrix-domain structure) in a solidified state.
[0019]
That is, in the hot melt adhesive of the present invention, each component is completely compatible and has transparency in a heated molten state, but some components are in a cooled solidified state. This is a micro phase separation, which is a feature that is greatly different from the conventional hot melt adhesive.
[0020]
In the hot melt adhesive of the present invention, if the components constituting the hot melt adhesive are not compatible in a molten state, the components are not uniformly compatible at the time of application to the adherend. Therefore, the adhesiveness to various adherends becomes insufficient.
[0021]
Further, in the hot melt adhesive of the present invention, if the solidified hot melt adhesive does not have a microphase-separated structure, as with the conventional hot melt adhesive, it has excellent heat resistance and excellent cold resistance. It is difficult to have both.
[0022]
The microphase separation of some components in the solidified state forms a microphase separation structure. In the microphase-separated structure, components forming domains between the lamellas of the main components forming the matrix form spindle-shaped domains.
[0023]
Although the hot-melt adhesive of the present invention is not particularly limited, the area of the domain is 1.5 × 10 5 in a plane section taken from the hot-melt adhesive. ² ~ 4.0 × 10 ⁶ nm ² And more preferably 5 × 10 ² ~ 4.0 × 10 ⁶ nm ² It is preferable that 25% by weight or more of the compounding amount of the domain forming component forms a domain.
[0024]
The area of the domain is 1.5 × 10 ² nm ² If the content is less than 25% or less than 25% by weight of the amount of the domain-forming component, the micro phase separation structure becomes incomplete, and the hot melt adhesive has excellent heat resistance and excellent cold resistance. In some cases, it may be difficult to combine the above with the other. ⁶ nm ² If it exceeds 300, the adhesiveness and cohesive force of the hot melt adhesive to various adherends may be reduced.
[0025]
The hot melt adhesive of the present invention is not particularly limited, but the spindle-shaped domain preferably has a minor axis of 0.010 μm or more and a major axis of 2 μm or less.
[0026]
When the minor axis of the spindle-shaped domain is less than 0.010 μm, the microphase separation structure becomes incomplete, and it becomes difficult for the hot melt adhesive to have both excellent heat resistance and excellent cold resistance. On the other hand, if the major axis of the spindle-shaped domain exceeds 2 μm, the adhesiveness and cohesive strength of the hot melt adhesive to various adherends may be reduced.
[0027]
The hot melt adhesive of the present invention is not particularly limited, but preferably contains an ethylene copolymer as a main component.
[0028]
Further, the hot melt adhesive of the present invention contains, but is not particularly limited to, an ethylene copolymer, a tackifying resin and a wax, and in a solidified state, adheres to the ethylene copolymer. It is preferable that the property-imparting resin is compatible with each other and has a microphase-separated structure formed of a matrix composed of the two compatible components and a domain composed of the wax.
[0029]
The ethylene-based copolymer that can be used as a main component in the hot melt adhesive of the present invention is not particularly limited, and examples thereof include various copolymers of ethylene and various ethylenically unsaturated monomers. Is mentioned. These ethylene copolymers may be used alone or in combination of two or more.
[0030]
The ethylenically unsaturated monomer is not particularly limited, and examples thereof include vinyl acetate, vinyl monocarboxylate, and acrylate. These ethylenically unsaturated monomers may be used alone or in combination of two or more.
[0031]
The content of the ethylenically unsaturated monomer in the ethylene copolymer is not particularly limited, but is preferably about 10 to 60% by weight, more preferably 12 to 45% by weight. It is.
[0032]
Further, the melt index (MI) of the ethylene copolymer is not particularly limited, but is preferably 0.1 to 10000 g / 10 minutes, more preferably 10 to 3000 g / 10 minutes. . In addition, MI mentioned here means M1 (g / 10 minutes) measured under the conditions of a temperature of 190 ° C. and a load of 2160 g in accordance with ASTM D-1238.
[0033]
In the present invention, among the above-mentioned ethylene copolymers, an ethylene-vinyl acetate copolymer is preferably used because it is excellent in balance among adhesiveness, flexibility, heating stability, price and the like.
[0034]
The ethylene-vinyl acetate copolymer is not particularly limited, but preferably has a vinyl acetate content of 28% by weight or more, more preferably 30% by weight or more, and particularly preferably 30 to 40%. % By weight.
[0035]
If the vinyl acetate content of the ethylene-vinyl acetate copolymer is less than 28% by weight, the resulting hot melt adhesive may have insufficient adhesion and cold resistance.
[0036]
In the present invention, the ethylene-vinyl acetate copolymer may be used alone, or two or more kinds having different vinyl acetate contents and MI may be used in combination.
[0037]
The tackifying resin that can be used in the hot melt adhesive of the present invention has excellent compatibility with the above-mentioned ethylene copolymer and the wax described below in a heat-melted state (at a temperature equal to or higher than the melting point of the wax), and has a solidified state. At (a temperature lower than the melting point of the wax), it is preferable that the material be kept compatible with the ethylene-based copolymer and be hardly compatible with the wax.
[0038]
In general, wax is often non-polar. From the above viewpoint, it is preferable to use a resin having a relatively high polarity as the tackifying resin.
[0039]
The preferred combination of the tackifying resin and the wax is not particularly limited, for example, the ethylene-based copolymer is an ethylene-vinyl acetate copolymer, and the wax is a non-polar paraffin wax. In some cases, the tackifying resin is preferably an aromatic tackifying resin having a relatively high polarity.
[0040]
Examples of the aromatic tackifying resin include, but are not particularly limited to, a resin having a C9 or C10 vinyl aromatic hydrocarbon as a main component such as vinyltoluene, indene, and α-methylstyrene; And styrene-based hydrocarbon resins which are (co) polymers such as vinyltoluene, α-methylstyrene, and isopropenyltoluene; coumarone-indene-based resins; and hydrogenated products thereof. These aromatic tackifying resins may be used alone or in combination of two or more. In addition, the (co) polymer mentioned here means a homopolymer or a copolymer.
[0041]
By using such an aromatic tackifying resin, the resulting hot melt adhesive is outstandingly superior to a hot melt adhesive using a tackifying resin other than the aromatic tackifying resin. It exhibits excellent heat resistance.
[0042]
The tackifying resin other than the aromatic tackifying resin is not particularly limited, for example, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, polyterpene resin, rosin resin And their hydrogenated products. These tackifying resins other than the aromatic tackifying resins may be used alone or in combination of two or more. The aromatic tackifying resin and the tackifying resin other than the aromatic tackifying resin may be used alone or in combination.
[0043]
Examples of the aliphatic hydrocarbon resin include, but are not particularly limited to, C4 or C5 monoolefin or diolefin such as 1-butene, isobutylene, butadiene, 1,3-pentadiene, isoprene, and piperidine. Examples thereof include (co) polymers as main components and hydrogenated products thereof. These aliphatic hydrocarbon resins may be used alone or in combination of two or more.
[0044]
The alicyclic hydrocarbon resin is not particularly limited. For example, a resin obtained by subjecting a diene component in a spent C4 or C5 fraction to cyclization dimerization and then (co) polymerized resin, Resins obtained by (co) polymerization of a cyclized monomer such as cyclopentadiene and the like, and hydrogenated products thereof are exemplified. These alicyclic hydrocarbon resins may be used alone or in combination of two or more.
[0045]
Examples of the polyterpene resin include, but are not particularly limited to, α-pinene (co) polymer, β-pinene (co) polymer, dipentene (co) polymer, terpene-phenol copolymer, α-pinene-phenol copolymers and hydrogenated products thereof. These polyterpene resins may be used alone or in combination of two or more.
[0046]
Examples of the rosin-based resin include, but are not limited to, rosins such as gum rosin, wood rosin, tall oil, and the like, modified products such as esterified products, disproportionated products, dimerized products, and the like. Additives and the like. The esterified product of rosin is not particularly limited, but examples include rosin ethylene glycol ester, diethylene glycol ester, glycerin ester, and pentaerythritol ester. These rosin-based resins may be used alone or in combination of two or more.
[0047]
The above-mentioned aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, polyterpene resin, rosin resin and the like, and hydrogenated products thereof, if necessary, are appropriately modified with an aromatic group-containing compound at an appropriate degree. It may be aromatically modified.
[0048]
The wax that can be used in the hot melt adhesive of the present invention is not particularly limited, for example, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, atactic polypropylene, and the like. Among them, for example, those imparted with a polarity by an oxidation treatment or the like, among which, among others, have low crystallinity and a relatively low melting point, and the obtained hot melt adhesive can achieve both heat resistance and cold resistance. Therefore, para-raffin wax is preferably used.
[0049]
These waxes may be used alone or in combination of two or more. For example, when a high melting point wax having a melting point of about 100 ° C. or more, such as Fischer-Tropsch wax, is used alone, it is obtained. Since the cold resistance of the hot melt adhesive may be impaired, in such a case, it is preferable to minimize the content of the high melting point wax in the hot melt adhesive.
[0050]
The content of the ethylene-based copolymer, the tackifying resin and the wax in the preferred hot melt adhesive of the present invention is not particularly limited, but based on 100 parts by weight of the ethylene-based copolymer. And 75 to 125 parts by weight of a tackifier resin and 12.5 to 75 parts by weight of a wax.
[0051]
If the content of the tackifier resin is less than 75 parts by weight based on 100 parts by weight of the ethylene copolymer, the adhesiveness and heat resistance of the hot melt adhesive to various adherends may be insufficient, If the content of the tackifying resin with respect to 100 parts by weight of the ethylene copolymer exceeds 125 parts by weight, the cold resistance of the hot melt adhesive may be impaired.
[0052]
When the content of the wax is less than 12.5 parts by weight based on 100 parts by weight of the ethylene-based copolymer, the melt viscosity of the hot melt adhesive may not be sufficiently reduced, or the solidification rate may be reduced, Conversely, if the wax content exceeds 75 parts by weight based on 100 parts by weight of the ethylene copolymer, the adhesiveness of the hot melt adhesive to various adherends may be insufficient.
[0053]
The preferred hot melt adhesive of the present invention is such that, in a solidified state, the ethylene-based copolymer and the tackifying resin are compatible, and the two-component matrix and the wax are compatible with each other. It is preferable to have a microphase-separated structure formed from a domain consisting of
[0054]
If the ethylene copolymer and the tackifying resin are not compatible with each other in the solidified hot melt adhesive, a preferable matrix cannot be formed in the microphase separation structure, or the adhesion to various adherends is poor. May be sufficient.
[0055]
In addition, if the hot melt adhesive in a solidified state does not have a microphase-separated structure formed of a matrix composed of the two components that are compatible with each other and a domain composed of the wax, excellent heat resistance can be obtained. In some cases, it may be difficult to combine excellent cold resistance, and it may not be possible to exhibit excellent adhesive performance over a wide temperature range.
[0056]
The presence or absence of the microphase separation structure in the present invention can be confirmed by, for example, the following method.
[0057]
[Method for confirming the presence or absence of micro phase separation structure]
A sample collected from the solidified hot melt adhesive is stained with a 2% by weight aqueous solution of osmium tetroxide for 24 hours, washed with water, further stained with ruthenium tetroxide gas for 2 hours, and washed with water. Then, after collecting ultra-thin sections of 70 nm in thickness using “REICHERTULTRACUT S” manufactured by Leica, and performing TEM analysis at an acceleration voltage of 120 KV using “JEM-1200EXII” manufactured by JEOL, The presence or absence of the micro phase separation structure is confirmed.
[0058]
FIGS. 1 and 2 show the results of TEM analysis after the above operation was performed on the hot melt adhesive. FIG. 1 is an electron micrograph showing a hot melt adhesive of the present invention (Example 1 described later) having a microphase separation structure in a solidified state, and FIG. 2 is a completely compatible system in a solidified state. 5 is an electron micrograph showing a conventional hot melt adhesive having no microphase separation structure (Comparative Example 1 described later).
[0059]
As shown in FIG. 1, in the hot melt adhesive of the present invention (Example 1) in a solidified state, a microphase-separated structure formed of a matrix and a domain is observed. On the other hand, as shown in FIG. 2, in the conventional (comparative example 1) hot-melt adhesive in a solidified state, no microphase-separated structure is observed.
[0060]
In the hot melt adhesive of the present invention, in addition to the ethylene copolymer, the tackifying resin and the wax, which are preferable components, if necessary as long as the object of the present invention is not hindered, for example, a filler, an increasing amount Agents, viscosity modifiers, thixotropic agents, softeners (plasticizers), antioxidants (antiaging agents), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, flame retardants, antistatic agents, etc. One or more of various additives may be added.
[0061]
[Action]
The hot melt adhesive of the present invention has excellent compatibility with various adherends because the components are compatible in a molten state and have a microphase-separated structure in a solidified state. It has both excellent heat resistance and excellent cold resistance, and exhibits excellent adhesive performance over a wide temperature range.
[0062]
Further, the hot melt adhesive of the present invention contains an ethylene copolymer, a tackifying resin and a wax, and in a solidified state, the ethylene copolymer and the tackifying resin are compatible with each other. And having a microphase-separated structure formed from a matrix consisting of the two components and the domain consisting of the wax, without increasing the cost. The above performance can be further improved.
[0063]
BEST MODE FOR CARRYING OUT THE INVENTION
EXAMPLES The present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In the examples, “parts” means “parts by weight”.
[0064]
(Example 1)
100 parts of ethylene-vinyl acetate copolymer (trade name “Evaflex V577-2ET”, vinyl acetate content: 33% by weight, MI: 400 g / 10 minutes, manufactured by Mitsui DuPont Polychemicals), unhydrogenated C9-based adhesive 100 parts of a property imparting resin (trade name “Hiresin RS-21”, softening point: 120 ° C., manufactured by Toho Chemical Co., Ltd.), 50 parts of paraffin wax (trade name “paraffin wax 155F”, melting point: 53 ° C., manufactured by Nippon Seiwa Co., Ltd.) And 180 parts of an antioxidant (trade name “Sumilyzer BHT”, manufactured by Sumitomo Chemical Co., Ltd.) were uniformly melt-kneaded at 180 ° C. to prepare a hot melt adhesive.
[0065]
(Example 2)
100 parts of an ethylene-vinyl acetate copolymer (trade name "Ultracene 726", vinyl acetate content: 33% by weight, MI: 700 g / 10 minutes, manufactured by Tosoh Corporation), an ethylene-vinyl acetate copolymer (trade name " Evaflex V577-2ET ", vinyl acetate content: 33% by weight, MI: 400 g / 10 minutes, 100 parts by Mitsui Dupont Polychemical Co., Ltd., styrene-based tackifying resin (trade name" FTR-6125 ", softening point) : 125 ° C, manufactured by Mitsui Petrochemical Co., Ltd.) 200 parts, 100 parts of paraffin wax “paraffin wax 155F” and 0.4 parts of antioxidant (trade name “Irganox 1010”, manufactured by Ciba Specialty Chemicals) at 180 ° C. To obtain a hot melt adhesive.
[0066]
(Example 3)
100 parts of ethylene-vinyl acetate copolymer (trade name “Evaflex V577-2ET”, vinyl acetate content: 33% by weight, MI: 400 g / 10 minutes, manufactured by Mitsui DuPont Polychemicals), unhydrogenated C9-based adhesive 100 parts of a property imparting resin (trade name “Petokol 120”, softening point: 120 ° C., manufactured by Tosoh Corporation) and 50 parts of paraffin wax (trade name “SP-0160”, melting point: 70 ° C., manufactured by Nippon Seiro Co., Ltd.) The mixture was uniformly melted and kneaded at a temperature of ° C to prepare a hot melt adhesive.
100 parts of unhydrogenated C9-based tackifying resin (trade name “Petcoal 120”, softening point: 120 ° C., manufactured by Tosoh Corporation), paraffin wax (trade name “SP-0160”, melting point: 70 ° C., Nippon Seiro Co., Ltd.) Was melted and kneaded uniformly at 180 ° C. to produce a hot melt adhesive.
(Comparative Example 1)
100 parts of ethylene-vinyl acetate copolymer (trade name “Evaflex 210”, vinyl acetate content: 28% by weight, MI: 400 g / 10 minutes, manufactured by Mitsui Dupont Polychemical Co., Ltd.), rosin phenol-based tackifying resin ( 100 parts of trade name “Tamanol 803L”, softening point: 145 ° C., manufactured by Arakawa Chemical Industries), 50 parts of paraffin wax “paraffin wax 155F” and 0.4 parts of antioxidant “Irganox 1010” at 180 ° C. The mixture was melt-kneaded to produce a hot melt adhesive.
[0067]
(Comparative Example 2)
100 parts of ethylene-vinyl acetate copolymer "Evaflex V577-2ET", 100 parts of rosin phenol-based tackifying resin "Tamanol 803L", 50 parts of paraffin wax "Paraffin wax 155F" and antioxidant "Irganox 1010" 0 .4 parts were uniformly melt-kneaded at 180 ° C. to prepare a hot melt adhesive.
[0068]
(Comparative Example 3)
100 parts of an ethylene-vinyl acetate copolymer “Evaflex 210”, 100 parts of a rosin ester-based tackifying resin (trade name “Super Ester A-125”, softening point: 125 ° C., manufactured by Arakawa Chemical Industries), paraffin wax 50 parts of “paraffin wax 155F” and 0.4 parts of antioxidant “Irganox 1010” were uniformly melt-kneaded at 180 ° C. to prepare a hot melt adhesive.
[0069]
(Comparative Example 4)
100 parts of an ethylene-vinyl acetate copolymer "Evaflex 210", 100 parts of an unhydrogenated C9-based tackifier resin (trade name "Petokol 120", softening point: 120 ° C, manufactured by Tosoh Corporation), paraffin wax (trade name) 50 parts of “SP-0160”, melting point: 70 ° C., manufactured by Nippon Seiro Co., Ltd.) were uniformly melt-kneaded at 180 ° C. to prepare a hot melt adhesive.
[0070]
The presence or absence of a microphase-separated structure (the presence of a matrix and a domain) in the solidified state of the hot melt adhesives obtained in Examples 1 to 3 and Comparative Examples 1 to 4 was confirmed by the above method. The results were as shown in Table 1.
[0071]
The performances ((1) heat creep resistance, (2) cold resistance) of the hot melt adhesives obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated by the following methods. The results were as shown in Table 1.
[0072]
As an adherend in the following performance evaluation, a K ″ liner was used for evaluation of heat creep resistance, and a cardboard (water-repellent treated liner) having poor adhesion was used for evaluation of cold resistance.
(1) Heat creep resistance)
As shown in FIG. 3, the adherends cut into 25 mm × 75 mm are coated with a hot-melt adhesive so that the adhesion area is 12 mm × 25 mm and the T-peeled state is obtained (application amount: 0.15 g / 5 cm length). The test piece for measurement was produced by bonding. Next, a load of 300 g was hung on one end of the non-adhesive part of the test piece for measurement, left in an oven at 55 ° C., and the time (minute) until the load was dropped was measured to evaluate the heat creep resistance. Was done.
(2) Cold resistance
As shown in FIG. 4, the adherends cut into 50 mm × 50 mm were bonded with a hot melt adhesive so that the bonding area was 12 mm × 50 mm (application amount: 0.15 g / 5 cm length), and a measurement test was performed. Pieces were made. Next, after leaving the test piece for measurement in an atmosphere at 0 ° C. for 24 hours, the test piece for measurement was forcibly peeled off by hand under the same atmosphere, and the material destruction rate (area%) of the adherend was measured. It measured and evaluated cold resistance.
[0073]
[Table 1]

[0074]
As is clear from Table 1, the hot melt adhesives of Examples 1 to 3 according to the present invention all exhibited excellent heat creep resistance and excellent cold resistance.
[0075]
On the other hand, the hot-melt adhesives of Comparative Examples 1 to 3, which did not have a microphase-separated structure in a solidified state, had excellent cold resistance, but extremely poor heat creep resistance. .
[0076]
【The invention's effect】
As described above, the hot melt adhesive of the present invention has excellent adhesiveness to various adherends, and has both excellent heat resistance and excellent cold resistance, and has excellent adhesive performance over a wide temperature range. It manifests itself and does not increase the cost because general-purpose raw materials are used. For example, it is suitably used as a hot melt adhesive for various industrial uses such as bookbinding, packaging, and woodworking.
[Brief description of the drawings]
FIG. 1 is an electron micrograph showing a hot melt adhesive of the present invention (Example 1) having a microphase separation structure in a solidified state.
FIG. 2 is an electron micrograph showing a conventional (Comparative Example 1) hot melt adhesive which is a completely compatible system in a solidified state and has no microphase separation structure.
FIG. 3 is a perspective view showing a method for evaluating heat creep resistance.
FIG. 4 is a perspective view showing a method for evaluating cold resistance.

Claims (7)

A hot melt adhesive characterized in that each component is compatible in a molten state and has a microphase separation structure (matrix-domain structure) in a solidified state. In a plane slice collected from the hot melt adhesive, the area of the domain is 1.5 × 10 ^{2 to} 4.0 × 10 ⁶ nm ² , and at least 25% by weight of the amount of the domain-forming component forms a domain. The hot melt adhesive according to claim 1, wherein the hot melt adhesive is used. The hot melt adhesive according to claim 1, wherein the domain has an area of 5 × 10 ^{2 to} 4.0 × 10 ⁶ nm ² . The hot melt adhesive according to any one of claims 1 to 3, wherein the hot melt adhesive comprises an ethylene-based copolymer as a main component. An ethylene copolymer, a tackifying resin and a wax are contained, and in a solidified state, the ethylene copolymer and the tackifying resin are compatible with each other, and The hot melt adhesive according to any one of claims 1 to 4, wherein the hot melt adhesive has a microphase-separated structure formed from a matrix composed of components and a domain composed of the wax. The hot melt adhesive according to claim 4 or 5, wherein the ethylene-based copolymer is an ethylene-vinyl acetate copolymer. The hot melt adhesive according to claim 6, wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of 30 to 40% by weight.

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