Hot melt adhesive

Abstract

To provide a hot melt adhesive that can reduce stringing and has excellent thermal stability, excellent adhesion to paper and a short set time.SOLUTION: Disclosed is a hot melt adhesive comprising: (A) a copolymer of ethylene with an olefin having 3 to 20 carbon atoms; (B) a copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond; and (C) a tackifying resin, wherein the (B) copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond comprises (B1) a copolymer of ethylene with a (meth)acrylic acid derivative, the copolymer (B1) having a melt flow rate of 1 to 38 g / 10 min.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hot melt adhesive, and more particularly to a hot melt adhesive that has good adhesion to various substrates and is particularly suitable for assembling paper substrates such as cardboard. [Background technology]

[0002] Hot melt adhesives are solvent-free adhesives that are applied to an adherend by heating and melting them, and then solidify upon cooling to develop adhesive properties. This allows for instant and high-speed bonding, and they are used in a wide range of fields, including paper processing, woodworking, sanitary materials, and electronics.

[0003] As the base polymer of the above-mentioned hot melt adhesive, depending on the application, for example, ethylene copolymers such as ethylene-vinyl acetate copolymer (hereinafter also referred to as "EVA") and ethylene-ethyl acrylate copolymer (hereinafter also referred to as "EEA"), olefin resins such as polyethylene, polypropylene, and amorphous polyalphaolefin (hereinafter also referred to as "APAO"), styrene block copolymers (for example, styrene-isoprene-styrene block copolymer (hereinafter also referred to as "SIS"), styrene-butadiene-styrene block copolymer (hereinafter also referred to as "SBS"), and synthetic rubbers such as hydrogenated products thereof, and polyurethanes are commonly used.

[0004] Among these hot melt adhesives, those using ethylene copolymers as the base polymer are often used in the fields of paper processing such as bookbinding and packaging, and woodworking. When applying hot melt adhesives, a dedicated applicator called a hot melt applicator is often used. Hot melt applicators have a nozzle that serves as an outlet, and the hot melt adhesive is heated to approximately 120-190°C and discharged from the tip of the nozzle to be applied to the adherend. When applying hot melt adhesive, threads of the hot melt adhesive may form between the tip of the nozzle and the adherend. These threads are caused by the stringiness of the hot melt adhesive and can stain the nozzle and the adherend. Therefore, developing hot melt adhesives with less stringiness is an important responsibility for adhesive manufacturers.

[0005] Patent Documents 1 to 3 disclose hot melt adhesives containing ethylene copolymers that aim to reduce stringiness. The hot melt adhesive of Patent Document 1 contains an ethylene / α-olefin copolymer and an ethylene carboxylic acid ester copolymer (see [Claim 1]

[0046] to

[0056] ). The hot melt adhesive of Patent Document 1 reduces the problem of thread formation. However, the thermal stability of the hot melt adhesive of Patent Document 1 is insufficient, and further improvement of the thermal stability is desired.

[0006] Patent Document 2 discloses a hot melt adhesive containing an ethylene-α-olefin copolymer, a functionalized ethylene-α-olefin copolymer, and an ethylene-(meth)acrylic acid ester copolymer (see [Claim 1]

[0053] to

[0067] ). The hot melt adhesive of Patent Document 2 can reduce stringiness to some extent, but its thermal stability is not sufficient. The hot melt adhesive of Patent Document 3, like Patent Document 2, contains a functionalized ethylene-α-olefin copolymer and an ethylene-(meth)acrylic acid ester copolymer (see

[0063] to

[0066] ), and therefore cannot be said to have excellent thermal stability.

[0007] In recent years, users' demands for reduced stringiness of hot melt adhesives have been increasing year by year, and the hot melt adhesives of Patent Documents 1 to 3 cannot be said to fully satisfy the high performance requirements of users in terms of reduced stringiness and thermal stability. It goes without saying that hot melt adhesives have excellent adhesion to adherends such as paper, and in recent years, they are also required to cure in a short time after being applied to an adherend, i.e., to have a short setting time. If a hot melt adhesive with a long setting time is applied to an adherend, it takes a long time for the adhesive to solidify, which reduces product productivity. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-177009 [Patent Document 2] Japanese Patent Application Publication No. 2019-26656 [Patent Document 3] Japanese Patent Application Publication No. 2019-34999 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a hot melt adhesive that can reduce stringiness, has excellent thermal stability, adhesion to paper, and has a short setting time. [Means for solving the problem]

[0010] As a result of extensive research, the present inventors have found that when a hot melt adhesive comprising (A) an ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and (C) a tackifier resin, wherein (B) the copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond comprises a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond with specific properties, a hot melt adhesive can be obtained that can solve the above-mentioned problems, and that such a hot melt adhesive is suitable for fields such as paper processing and woodworking, and have completed the present invention.

[0011] The present specification includes the following embodiments. 1. Comprising (A) an ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and (C) a tackifier resin, (B) A hot melt adhesive, wherein the copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond includes (B1) a copolymer of ethylene and a (meth)acrylic acid derivative having a melt flow rate of 1 to 38 g / 10 min. 2. The hot melt adhesive according to 1, wherein the content of (B1) is 1 to 10 parts by mass per 100 parts by mass of the total amount of components (A) to (C). 3. The hot melt adhesive according to 1 or 2, wherein component (B1) comprises a copolymer of ethylene and a (meth)acrylic acid ester (ethylene / (meth)acrylic acid ester copolymer). 4. The hot melt adhesive according to 3, wherein the component (B1) comprises an ethylene / (meth)acrylic acid ester copolymer having a content of structural units derived from a (meth)acrylic acid ester of 2 to 24 mass %. 5. The hot melt adhesive according to 3 or 4, wherein component (B1) contains at least one ethylene / (meth)acrylic acid ester copolymer selected from ethylene / methyl methacrylate copolymer, ethylene / butyl acrylate copolymer, and ethylene / ethyl acrylate. 6. The hot melt adhesive according to any one of 1 to 5, further comprising (D) a wax, wherein (D) the wax comprises a Fischer-Tropsch wax. 7. A hot melt adhesive according to 6, wherein the Fischer-Tropsch wax content is 80 mass% or more relative to 100 mass parts of the total amount of (D) wax. 8. The hot melt adhesive according to any one of 1 to 7, wherein the tackifying resin (C) comprises a partially hydrogenated tackifying resin (C1) and a fully hydrogenated tackifying resin (C2). 9. A hot melt adhesive according to any one of 1 to 8, wherein (C) the tackifying resin comprises a hydrocarbon resin having a softening point of less than 120°C and a hydrocarbon resin having a softening point of 120°C or higher. 10. A paper product having the hot melt adhesive according to any one of 1 to 9. [Effects of the Invention]

[0012] The hot melt adhesive of the embodiment of the present invention can reduce stringiness, has excellent thermal stability and adhesion to paper, and further has a short setting time, which can contribute to improving product productivity. When the hot melt adhesive of the embodiment of the present invention is applied from a nozzle to an adherend such as paper, the nozzle and the adherend are not soiled with thread-like matter. Even if the hot melt adhesive is stored in a storage tank for a long period of time, no carbonization or sedimentation occurs, viscosity increase is suppressed, and there is no adverse effect on the application work. DETAILED DESCRIPTION OF THE INVENTION

[0013] The hot melt adhesive of an embodiment of the present invention contains, as essential components, (A) an ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and (C) a tackifier resin. In this specification, the term "hot melt adhesive" refers to an adhesive that is solid at room temperature but becomes fluid when heated and melted, and can be applied to an object such as a substrate or an adherend, and hardens and adheres when cooled.

[0014] <(A) Ethylene / C3-20 Olefin Copolymer> In the embodiments of the present invention, the term "(A) ethylene / olefin copolymer having 3 to 20 carbon atoms" refers to a copolymer of ethylene and an olefin having 3 to 20 carbon atoms, and is not particularly limited as long as the hot melt adhesive intended by the present invention can be obtained. Specific examples of "olefins having 3 to 20 carbon atoms" include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, cis-2-butene, trans-2-butene, isobutylene, cis-2-pentene, trans-2-pentene, 3-methyl-1-butene, 2-methyl-2-butene, and 2,3-dimethyl-2-butene. Olefins having 3 to 10 carbon atoms are preferred, and propylene, butene, hexene, and octene are more preferred, propylene, butene, and octene are even more preferred, and octene is particularly preferred.

[0015] The (A) ethylene / olefin copolymer having 3 to 20 carbon atoms is preferably a copolymer polymerized using a metallocene catalyst. By including the (A) copolymer polymerized using a metallocene catalyst (metallocene-based ethylene / olefin copolymer having 3 to 20 carbon atoms), the hot melt adhesive according to the embodiment of the present invention becomes hard and less likely to become stringy.

[0016] Examples of (A) ethylene / olefin copolymers having 3 to 20 carbon atoms include a copolymer of ethylene and octene (ethylene / octene copolymer), a copolymer of ethylene and propylene and 1-butene (ethylene / propylene / butene copolymer), a copolymer of ethylene and propylene (ethylene / propylene copolymer), a copolymer of ethylene and butene (ethylene / butene copolymer), and a copolymer of ethylene and hexene (ethylene / hexene copolymer). In particular, (A) ethylene / olefin copolymer having 3 to 20 carbon atoms preferably includes a copolymer of ethylene and octene, a copolymer of ethylene and propylene, a copolymer of ethylene and butene, or a copolymer of ethylene and hexene, and more preferably includes a copolymer of ethylene and octene. (A) ethylene / olefin copolymer having 3 to 20 carbon atoms can be a commercially available product.

[0017] Examples of ethylene / octene copolymers include Affinity GA1900 (trade name), Affinity GA1950 (trade name), Affinity GA1875 (trade name), Affinity GA1000R (trade name), Affinity EG8185 (trade name), Affinity EG8200 (trade name), Engage 8137 (trade name), Engage 8180 (trade name), and Engage 8400 (trade name), all manufactured by The Dow Chemical Company. Examples of ethylene / propylene / 1-butene copolymers include Bestplast 730 (trade name) and Bestplast 708 (trade name) manufactured by Evonik Degussa. Examples of ethylene / propylene copolymers include Eastoflex E1016PL-1 manufactured by Eastman Chemical Company and Vistamax (trade name) series manufactured by ExxonMobil Corporation.

[0018] An example of the ethylene / butene copolymer is Tafmer A4085 manufactured by Mitsui Chemicals. An example of an ethylene / hexene copolymer is Nipolon Z HM510R manufactured by Tosoh Corporation. Such copolymers of ethylene and an olefin having 3 to 20 carbon atoms can be used alone or in combination. In the present invention, in consideration of reducing stringiness, the (A) ethylene / olefin copolymer having 3 to 20 carbon atoms is preferably an ethylene / octene copolymer.

[0019] <(B) Copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond> In an embodiment of the present invention, the “(B) copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond” (hereinafter also referred to as “(B) copolymer” or “component (B)”) is a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and is not particularly limited as long as the hot melt adhesive targeted by the present invention can be obtained.

[0020] In this specification, the term "carboxylic acid derivative having an ethylenic double bond" refers to a carboxylic acid derivative (including carboxylic acid) having a carbon-carbon double bond capable of addition polymerization with ethylene, and specifically refers to, for example, in this specification, "carboxylic acid having an ethylenic double bond," "carboxylic acid anhydride having an ethylenic double bond," "carboxylic acid ester having an ethylenic double bond," and the like.

[0021] The "carboxylic acid having an ethylenic double bond" is a compound having an ethylenic double bond and a carboxyl group, and is not particularly limited as long as it can produce the hot melt adhesive of the present invention. Specific examples include oleic acid, linoleic acid, maleic acid, itaconic acid, acrylic acid, and methacrylic acid. The "carboxylic acid anhydride having an ethylenic double bond" refers to a compound obtained by dehydration condensation of two carboxylic acid molecules or a compound obtained by dehydrating two carboxyl groups in one molecule, and is not particularly limited as long as it can produce the hot melt adhesive of the present invention. Specific examples include fumaric anhydride and maleic anhydride.

[0022] Examples of the "carboxylic acid ester having an ethylenic double bond" include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, and vinyl and allyl carboxylate esters such as vinyl acetate and allyl acetate. In this specification, the term "(meth)acrylic acid ester" refers to both acrylic acid ester and methacrylic acid ester.

[0023] In an embodiment of the present invention, the "carboxylic acid ester having an ethylenic double bond" preferably includes a (meth)acrylic acid ester such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, more preferably includes methyl (meth)acrylate, ethyl (meth)acrylate, or butyl (meth)acrylate, and particularly preferably includes methyl methacrylate or ethyl acrylate.

[0024] Examples of the "(B) copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond" include a copolymer of ethylene and a carboxylic acid having an ethylenic double bond (ethylene / carboxylic acid copolymer having an ethylenic double bond), a copolymer of ethylene and a carboxylic acid anhydride having an ethylenic double bond (ethylene / carboxylic acid anhydride copolymer having an ethylenic double bond), and a copolymer of ethylene and a carboxylic acid ester having an ethylenic double bond (ethylene / carboxylic acid ester copolymer having an ethylenic double bond).

[0025] Examples of copolymers of ethylene and a carboxylic acid having an ethylenic double bond include a copolymer of ethylene and (meth)acrylic acid (ethylene / (meth)acrylic acid copolymer), and examples of copolymers of ethylene and a carboxylic acid ester having an ethylenic double bond include a copolymer of ethylene and a (meth)acrylic acid ester (ethylene / (meth)acrylic acid ester copolymer); a copolymer of ethylene and a vinyl carboxylate (ethylene / vinyl carboxylate copolymer); and a copolymer of ethylene and an allyl carboxylate (ethylene / allyl carboxylate copolymer).

[0026] In an embodiment of the present invention, (B) the copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond preferably includes a “copolymer of ethylene and a (meth)acrylic acid derivative.” The “copolymer of ethylene and a (meth)acrylic acid derivative” preferably includes at least one selected from an ethylene / (meth)acrylic acid ester copolymer, an ethylene / (meth)acrylic acid copolymer, and an ethylene / (meth)acrylic anhydride copolymer, and most preferably includes an ethylene / (meth)acrylic acid ester copolymer. By including a "copolymer of ethylene and a (meth)acrylic acid derivative" in component (B), the hot melt adhesive of the embodiment of the present invention can reduce stringiness and further improve thermal stability.

[0027] The copolymer of ethylene and a (meth)acrylic acid derivative preferably contains a copolymer of ethylene and a (meth)acrylic acid ester (ethylene / (meth)acrylic acid ester copolymer), more preferably contains at least one selected from an ethylene / methyl (meth)acrylate copolymer, an ethylene / ethyl (meth)acrylate copolymer, an ethylene / butyl (meth)acrylate copolymer, and an ethylene / 2-ethylhexyl (meth)acrylate copolymer, even more preferably contains at least one selected from an ethylene / methyl (meth)acrylate copolymer, an ethylene / ethyl (meth)acrylate copolymer, and an ethylene / butyl (meth)acrylate copolymer, and in particular, it is desirable to contain an ethylene / methyl methacrylate copolymer and / or an ethylene / ethyl acrylate copolymer.

[0028] In an embodiment of the present invention, component (B) comprises (B1) a copolymer of ethylene and a (meth)acrylic acid derivative, and the melt flow rate of component (B1) may be 1 to 38 g / 10 min, or may be 1 to 35 g / 10 min, preferably 1 to 30 g / 10 min, and most preferably 2 to 25 g / 10 min. When the melt flow rate of component (B1) is within the above range, the hot melt adhesive of the present invention exhibits reduced stringiness and improved thermal stability. Note that, in this specification, the melt flow rate is a value measured in accordance with JIS K7210 at 190°C under a load of 2.16 kg.

[0029] (B1) Examples of the copolymer of ethylene and a (meth)acrylic acid derivative include an ethylene / (meth)acrylic acid copolymer, an ethylene / (meth)acrylic acid ester copolymer, and an ethylene / (meth)acrylic anhydride copolymer. As long as the hot melt adhesive targeted by the present invention can be obtained, the copolymer of ethylene and a (meth)acrylic acid derivative (B1) is not particularly limited, but it is particularly preferable that it contains an ethylene / (meth)acrylic acid ester copolymer.

[0030] The ethylene / (meth)acrylic acid ester copolymer contained in component (B1) preferably contains at least one selected from ethylene / methyl methacrylate copolymer, ethylene / butyl acrylate copolymer, ethylene / ethyl acrylate, and ethylene / 2-ethylhexyl (meth)acrylate copolymer, more preferably contains at least one selected from ethylene / methyl methacrylate copolymer, ethylene / butyl acrylate copolymer, and ethylene / ethyl acrylate, particularly preferably contains ethylene / methyl methacrylate copolymer and / or ethylene / butyl acrylate copolymer, and most preferably contains ethylene / methyl methacrylate copolymer. When component (B1) contains an ethylene / (meth)acrylic acid ester copolymer, the hot melt adhesive of an embodiment of the present invention can further reduce stringiness, maintain excellent thermal stability, have excellent adhesion to paper, and achieve a short setting time.

[0031] The ethylene / (meth)acrylic acid ester copolymer contained in component (B1) preferably has a content of structural units derived from (meth)acrylic acid ester of 2 to 24 mass%, particularly preferably 4 to 24 mass%, further preferably 6 to 24 mass%, and most preferably 7 to 24 mass%. When the content of structural units derived from (meth)acrylic acid ester in the ethylene / (meth)acrylic acid ester copolymer contained in component (B1) is within the above-mentioned range, the thermal stability of the hot melt adhesive of an embodiment of the present invention can be significantly improved.

[0032] In this specification, the content of structural units derived from (meth)acrylic acid esters in the ethylene / (meth)acrylic acid ester copolymer contained in (B1) refers to the mass % of structural units derived from (meth)acrylic acid esters relative to the total amount of the ethylene / (meth)acrylic acid ester copolymer (B1). The ethylene / (meth)acrylic acid ester copolymer contained in (B1) has a chemical structure derived from ethylene and a chemical structure derived from a (meth)acrylic acid ester.

[0033] The term "structural unit derived from a (meth)acrylic acid ester" refers to a chemical structure derived from a (meth)acrylic acid ester among the chemical structures possessed by an ethylene / (meth)acrylic acid ester copolymer. For example, an ethylene / methyl methyl methacrylate copolymer with a methyl methyl methacrylate content of 20% by mass means that the total amount of chemical structures derived from methyl methyl methacrylate is 20 parts by mass per 100 parts by mass of the total mass of (B1).

[0034] In this specification, the content of structural units derived from ethylene / (meth)acrylic acid ester compounds can be measured by infrared absorption spectroscopy using a pressed sheet of component (B1). For example, when the (meth)acrylic acid ester is methyl methacrylate, the content of structural units derived from methyl methacrylate in an ethylene / methyl methacrylate copolymer can be measured according to JIS K7192. As the characteristic absorption of the infrared absorption spectrum, a peak attributed to the (meth)acrylic acid ester copolymer is used, and the absorbance is corrected by the thickness of the press sheet to determine the comonomer content. For example, when the (meth)acrylic acid ester is methyl methacrylate, the content of methyl methacrylate units in the ethylene / methyl methacrylate copolymer can be measured by infrared absorption spectroscopy using an infrared spectrometer after preparing a press sheet with a thickness of 0.3 mm. As the characteristic absorption of the infrared absorption spectrum, a peak at 3448 cm attributed to methyl methacrylate is used. -1 Using the peak, the absorbance is corrected for thickness according to the following formula to determine the content. MMA = 4.1 × log(I0 / I) / t - 5.3 [In the formula, MMA is the content (mass%) of methyl methacrylate units, and I is the frequency of 3448 cm -1 The transmitted light intensity at the frequency 3448 cm -1 where t is the thickness (cm) of the sample sheet.

[0035] The method for producing the copolymer (B1) of ethylene and a (meth)acrylic acid derivative is not particularly limited, and examples thereof include known liquid phase polymerization methods, high-pressure radical polymerization methods, etc. Examples of methods for producing component (B1) by high-pressure radical polymerization include a method in which ethylene and a (meth)acrylic acid derivative (e.g., a (meth)acrylic acid ester) are polymerized in the presence of a radical generator, typically using a tank reactor or tubular reactor, under conditions of a polymerization pressure of 140 MPa to 300 MPa and a polymerization temperature of 100°C to 300°C. Additionally, hydrocarbons such as hydrogen, methane and ethane can be used as molecular weight regulators to adjust the melt flow rate.

[0036] As the (B1) copolymer of ethylene and a (meth)acrylic acid derivative, commercially available products can be used. Acryft WH401-F (trade name), Acryft WH206-F (trade name), Acryft WD301-F (trade name), Acryft WD203-1 (trade name), and the like, manufactured by Sumitomo Chemical Co., Ltd.; Lotril 17BA07N (trade name), Lotril 24MA02N (trade name), Lotader 4503 (trade name), and the like, manufactured by Arkema; NUC-6220 (trade name) and DPDJ-9169 (trade name) manufactured by The Dow Chemical Company, etc.; Nuclell N1035 (trade name) manufactured by Mitsui Dow Chemical Company; Escor 5080 (product name) manufactured by Exxon Mobil Examples include:

[0037] (B) The copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond may contain other copolymers of ethylene and a carboxylic acid derivative having an ethylenic double bond (component (B2)) that do not fall under the category of component (B1) the copolymer of ethylene and a (meth)acrylic acid derivative having a melt flow rate of 1 to 38 g / 10 min.

[0038] Component (B2) is a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, which does not fall under component (B1), and specifically, for example, A copolymer of ethylene and a (meth)acrylic acid derivative having a melt flow rate of more than 38 g / 10 min; Copolymers of ethylene and (meth)acrylic acid derivatives having a melt flow rate of less than 1 g / 10 min; and Copolymers of ethylene and carboxylic acid derivatives having an ethylenic double bond (excluding (meth)acrylic acid derivatives), such as copolymers of ethylene and itaconic acid derivatives (ethylene / itaconic acid derivative copolymers), copolymers of ethylene and vinyl acetate (ethylene / vinyl acetate copolymers), and copolymers of ethylene and allyl carboxylate (ethylene / allyl carboxylate copolymers).

[0039] <(C) Tackifying resin> The tackifying resin (C) is not particularly limited as long as it is commonly used in hot melt adhesives and can provide the hot melt adhesive of the present invention. In consideration of the hot melt adhesive of the present invention, it is preferable to include both a partially hydrogenated tackifying resin (C1) and a fully hydrogenated tackifying resin (C2). In this specification, (C1) partially hydrogenated tackifying resin is a tackifier in which hydrogen is added to some of the double bonds in the tackifier, and (C2) fully hydrogenated tackifying resin is a tackifier in which hydrogen is added to all of the double bonds in the tackifier. The (C1) partially hydrogenated tackifying resin has good compatibility with the (B) copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and the (C2) fully hydrogenated tackifying resin has good compatibility with the (A) ethylene / olefin copolymer having 3 to 20 carbon atoms. In other words, when the (C) tackifying resin contains both components (C1) and (C2), the compatibility of the hot melt adhesive is improved, and as a result, the thermal stability is significantly improved.

[0040] Examples of (C) tackifying resins include natural rosin, modified rosin, hydrogenated rosin, glycerol esters of natural rosin, glycerol esters of modified rosin, pentaerythritol esters of natural rosin, pentaerythritol esters of modified rosin, pentaerythritol esters of hydrogenated rosin, copolymers of natural terpenes, three-dimensional polymers of natural terpenes, hydrogenated derivatives of hydrogenated terpene copolymers, polyterpene resins, hydrogenated derivatives of phenolic modified terpene resins, aliphatic petroleum hydrocarbon resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, aromatic petroleum hydrocarbon resins, hydrogenated derivatives of aromatic petroleum hydrocarbon resins, cycloaliphatic petroleum hydrocarbon resins, and hydrogenated derivatives of cycloaliphatic petroleum hydrocarbon resins. These tackifying resins can be used alone or in combination. Liquid tackifying resins can also be used as long as they are colorless to pale yellow, substantially odorless, and have good thermal stability.

[0041] The tackifying resin (C) preferably contains both a hydrocarbon resin with a softening point of less than 120°C and a hydrocarbon resin with a softening point of 120°C or higher. By containing both a hydrocarbon resin with a softening point of less than 120°C and a hydrocarbon resin with a softening point of 120°C or higher, the hot melt adhesive of an embodiment of the present invention can further improve adhesion, further reduce stringiness, and achieve even better thermal stability. The softening point of the tackifying resin (C) is measured in accordance with JIS K2207.

[0042] Commercially available products can be used as the (C) tackifying resin. Examples of such commercially available products include T-REZ HC103 (trade name), T-REZ HA103 (trade name), and T-REZ HA125 (trade name) manufactured by Eneos Corporation, ECR5600 (trade name) manufactured by ExxonMobil Corporation, Maruka Clear H (trade name) manufactured by Maruzen Petrochemical Co., Ltd., Clearon K100 (trade name) manufactured by Yasuhara Chemical Co., Ltd., Arkon M100 (trade name) manufactured by Arakawa Chemical Co., Ltd., Imerv S100 (trade name), Imerv Y135 (trade name), and Imerv P125 (trade name) manufactured by Idemitsu Petrochemical Co., Ltd., Clearon K4090 (trade name) and Clearon K4100 manufactured by Yasuhara Chemical Co., Ltd., ECR231C (trade name) and ECR179EX (trade name) manufactured by ExxonMobil Corporation, and Rigalite R7100 (trade name) manufactured by Eastman Chemical Company. These commercially available tackifying resins can be used alone or in combination.

[0043] As the (C1) partially hydrogenated tackifying resin, commercially available products can be used, such as T-REZ HC103 (trade name) manufactured by Eneos Corporation and Alcon M100 (trade name) manufactured by Arakawa Chemical Industries, Ltd., and as the (C2) fully hydrogenated tackifying resin, such as T-REZ HA103 (trade name), T-REZ HA125 (trade name), and Imarv P125 (trade name) manufactured by Idemitsu Petrochemical Co., Ltd. are preferred.

[0044] The hot melt adhesive of an embodiment of the present invention preferably contains 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and most preferably 2 to 7 parts by mass of (B1) the copolymer of ethylene and a (meth)acrylic acid derivative per 100 parts by mass of the total of (A) the ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) the copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and (C) the tackifier resin. When the content of the (B1) copolymer of ethylene and a (meth)acrylic acid derivative is within the above-mentioned range, the hot melt adhesive of an embodiment of the present invention exhibits reduced stringiness, highly improved thermal stability and adhesion to paper, and a shorter setting time.

[0045] In the hot melt adhesive of an embodiment of the present invention, the (A) ethylene / olefin copolymer having 3 to 20 carbon atoms is preferably contained in an amount of 25 to 60 parts by mass, more preferably 30 to 55 parts by mass, and most preferably 30 to 50 parts by mass, per 100 parts by mass of the total of (A) ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and (C) tackifier resin. When the content of (A) ethylene / olefin copolymer having 3 to 20 carbon atoms is within the above-mentioned range, the hot melt adhesive of an embodiment of the present invention exhibits further reduced stringiness, highly improved thermal stability and adhesion to paper, and a shorter setting time.

[0046] <(D) Wax> The hot melt adhesive of the present invention preferably further comprises (D) a wax. In this specification, the term "wax" refers to an organic substance that is solid at room temperature and becomes liquid when heated, and has a weight average molecular weight of less than 10,000, which is generally considered to be a "wax." There are no particular limitations on the type of wax that can be used as long as it has wax-like properties and can provide the hot melt adhesive of the present invention.

[0047] Examples of waxes include Fischer-Tropsch wax, paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, etc. Commercially available waxes can be used, and the waxes can be used alone or in combination.

[0048] In an embodiment of the present invention, the wax (D) preferably contains Fischer-Tropsch wax. "Fischer-Tropsch wax" refers to a substance synthesized by the Fischer-Tropsch process and generally known as Fischer-Tropsch wax. Fischer-Tropsch wax is obtained by separating a wax whose component molecules have a narrow carbon number distribution from a wax whose component molecules have a relatively wide carbon number distribution. Representative Fischer-Tropsch waxes include Sasol H1 (trade name), Sasol C105, and Sasol C80 (trade name), all of which are commercially available from Sasol Waxes. By including Fischer-Tropsch wax, the hot melt adhesive of an embodiment of the present invention exhibits excellent thermal stability and adhesive strength in high temperature regions.

[0049] The melting point of the wax may be, for example, 60 to 160°C, or 65 to 150°C. The melting point of the Fischer-Tropsch wax is preferably 70 to 120°C. The melting point of wax is a value measured using differential scanning calorimetry (DSC). Specifically, 10 mg of a sample is weighed into an aluminum container using a DSC6220 (trade name) manufactured by SII Nano Technology Co., Ltd., and the temperature at the top of the melting peak is measured at a heating rate of 10°C / min.

[0050] The content of the Fischer-Tropsch wax is preferably 80 mass% or more relative to 100 mass parts of the total amount of the wax (D). By having the Fischer-Tropsch wax content in the above range, the thermal stability of the hot melt adhesive of the present invention is further improved.

[0051] In an embodiment of the present invention, the (B1) copolymer of ethylene and a (meth)acrylic acid derivative is preferably contained in an amount of 1 to 10 parts by mass, more preferably 2 to 10 parts by mass, and most preferably 2 to 6 parts by mass, per 100 parts by mass of the total of (A) ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, (C) tackifier resin, and (D) wax. When the content of (B1) the copolymer of ethylene and a (meth)acrylic acid derivative in the hot melt adhesive according to an embodiment of the present invention is within the above-mentioned range, stringiness is further reduced and the thermal stability, adhesion to paper, and setting ability are improved to a high level.

[0052] In an embodiment of the present invention, the (A) ethylene / olefin copolymer having 3 to 20 carbon atoms is preferably contained in an amount of 20 to 50 parts by mass, more preferably 25 to 45 parts by mass, and most preferably 25 to 40 parts by mass, per 100 parts by mass of the total of (A) ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, (C) tackifier resin, and (D) wax. When the content of (A) ethylene / olefin copolymer having 3 to 20 carbon atoms is within the above-mentioned range, the hot melt adhesive of an embodiment of the present invention further reduces stringiness and highly improves thermal stability, adhesion to paper, and setting ability.

[0053] In an embodiment of the present invention, the tackifier resin (C) is preferably contained in an amount of 30 to 60 parts by mass, more preferably 35 to 55 parts by mass, and most preferably 40 to 55 parts by mass, per 100 parts by mass of the total of (A) ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, (C) tackifier resin, and (D) wax. When the content of the tackifying resin (C) in the hot melt adhesive according to an embodiment of the present invention is within the above-mentioned range, stringiness is further reduced and thermal stability, adhesion to paper, and setting ability are improved to a high level.

[0054] The hot melt adhesive of the present invention may further contain various additives as needed, such as plasticizers, stabilizers (ultraviolet absorbers, antioxidants), and particulate fillers. The "plasticizer" is blended to reduce the melt viscosity of the hot melt adhesive, impart flexibility, and improve wetting to the adherend. It is not particularly limited as long as it is compatible with components (A) and (B) and can provide the hot melt adhesive of the present invention. Examples of plasticizers include paraffinic oil, naphthenic oil, and aromatic oil. Colorless and odorless paraffinic oil is particularly preferred.

[0055] Commercially available plasticizers can be used. Examples include White Oil Broom 350 (trade name) manufactured by Kukdong Oil & Chem Co., Ltd., Diana Fresia S32 (trade name), Diana Process Oil PW-90 (trade name), DN Oil KP-68 (trade name) manufactured by Idemitsu Kosan Co., Ltd., Enerper M1930 (trade name) manufactured by BP Chemicals, Kaydol (trade name) manufactured by Crompton, and Primol 352 (trade name) manufactured by Esso Corporation. These plasticizers can be used alone or in combination.

[0056] The "stabilizer" is a compound that is added to improve the stability of the hot melt adhesive by preventing molecular weight reduction, gelation, coloration, odor generation, etc., of the hot melt adhesive due to heat, air, light, etc., and is not particularly limited as long as it can provide the hot melt adhesive that is the object of the present invention. Examples of stabilizers include antioxidants and ultraviolet absorbers.

[0057] The "ultraviolet absorber" is used to improve the light resistance of the hot melt adhesive. The "antioxidant" is used to prevent oxidative degradation of the hot melt adhesive. Antioxidants and ultraviolet absorbers are generally used in hot melt adhesives, and are not particularly limited as long as they can produce the desired paper product described below.

[0058] Examples of "antioxidants" include phenol-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers. Furthermore, lactone-based stabilizers can also be added. These can be used alone or in combination.

[0059] Commercially available stabilizers can be used. Examples include Sumilizer GM (trade name), Sumilizer TPD (trade name), and Sumilizer TPS (trade name) manufactured by Sumitomo Chemical Co., Ltd., Irganox 1010 (trade name), Irganox HP2225FF (trade name), Irgafos 168 (trade name), and Irganox 1520 (trade name) manufactured by Ciba Specialty Chemicals, Adeka Stab AO-60 (trade name) manufactured by ADEKA, and JF77 (trade name) and JP-650 (trade name) manufactured by Johoku Chemical Co., Ltd. These stabilizers can be used alone or in combination.

[0060] The hot melt adhesive of the present invention may further contain a particulate filler. The particulate filler may be any commonly used filler, and is not particularly limited as long as the hot melt adhesive of the present invention can be obtained. Examples of "particulate fillers" include mica, calcium carbonate, kaolin, talc, titanium oxide, diatomaceous earth, urea resin, styrene beads, calcined clay, and starch. The shape of these fillers is preferably spherical, and their dimensions (diameter in the case of spheres) are not particularly limited.

[0061] The hot melt adhesive of the present invention can be produced by a commonly known method for producing a hot melt adhesive, by blending (A) an ethylene / olefin copolymer having 3 to 20 carbon atoms, (B) a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, and (C) a tackifier resin, and further, if necessary, (D) a wax and / or the various additives described above. For example, the adhesive can be produced by blending the above-mentioned components in predetermined amounts and heating and melting them. The order in which the components are added, the heating method, etc. are not particularly limited as long as the desired hot melt adhesive can be obtained.

[0062] The method for applying the hot melt adhesive is not particularly limited as long as the desired paper product can be obtained, but a hot melt applicator is widely used. Examples of hot melt applicators include Problue P4 Melter (trade name) and Problue P10 Melter (trade name) manufactured by Nordson Corporation.

[0063] Coating methods are broadly classified into, for example, contact coating and non-contact coating. "Contact coating" refers to a coating method in which a sprayer is brought into contact with a member or film when coating a hot melt adhesive, and "non-contact coating" refers to a coating method in which a sprayer is not brought into contact with a member or film when coating a hot melt adhesive. Examples of contact coating methods include slot coater coating and roll coater coating, while examples of non-contact coating methods include spiral coating, which allows for spiral coating, omega coating and control seam coating, which allow for wave-like coating, slot spray coating and curtain spray coating, which allow for planar coating, dot coating, which allows for spot-like coating, and bead coating, which allows for linear coating.

[0064] When applying the hot melt adhesive of the present invention using a hot melt applicator (even when the hot melt applicator dispenses the hot melt adhesive horizontally to the ground), almost no threads of the hot melt adhesive are dispensed, and therefore the adherend and the applicator are not soiled with the threads.

[0065] The hot melt adhesive of the embodiment of the present invention is widely used in, for example, electronic components, woodworking, building materials, sanitary materials, paper products, etc., but can also be suitably used to produce paper products and is useful as a hot melt adhesive for paper products.

[0066] The paper product of the embodiment of the present invention refers to a paper product manufactured using the above-mentioned hot melt adhesive. The type of paper product is not particularly limited as long as it is manufactured using the above-mentioned hot melt adhesive, but specific examples include bookbinding, calendars, cardboard, cartons, etc. Considering the properties of the hot melt adhesive of the embodiment of the present invention, thick paper such as cardboard and cartons is particularly effective as the paper product of the embodiment of the present invention. [Example]

[0067] The present invention will be described below using examples for the purpose of explaining the present invention in more detail and more specifically. These examples are for the purpose of explaining the present invention, but are not intended to limit the present invention in any way.

[0068] The components to be blended into the hot melt adhesive are shown below. (A) Ethylene / C3-20 olefin copolymer (A1) Ethylene / octene copolymer (1-octene content: 35 to 37% by mass, melt flow rate: 1000 g / 10 min, Affinity GA1900 (trade name) manufactured by The Dow Chemical Company) (A2) Ethylene / octene copolymer (1-octene content: 35 to 37% by mass, melt flow rate: 500 g / 10 min, Affinity GA1950 (trade name) manufactured by The Dow Chemical Company) (A3) Ethylene / octene copolymer (1-octene content: 35 to 37% by mass, melt flow rate: 1200 g / 10 min, Affinity GA1875 (trade name) manufactured by The Dow Chemical Company) (A4) Ethylene / octene copolymer (1-octene content: 30 to 40% by weight, melting point: 68°C, melt flow rate: 660 g / 10 min, Affinity GA1000R (trade name) manufactured by The Dow Chemical Company) (A5) Ethylene / propylene copolymer (ethylene content: 6.0% by mass, melting point: 97°C, melt viscosity at 190°C: 1200 mPas, Vistamax 88880 (trade name) manufactured by ExxonMobil Corporation) (A6) Ethylene / hexene copolymer (Nipolon Z HM510R (trade name) manufactured by Tosoh Corporation)

[0069] (B) Copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond (B1) A copolymer of ethylene and a (meth)acrylic acid derivative having a melt flow rate of 1 to 38 g / 10 min (B1-1) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 20% by mass, melt flow rate: 20 g / 10 min, Acryft WH401-F (product name) manufactured by Sumitomo Chemical Co., Ltd.) (B1-2) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 20% by mass, melt flow rate: 2 g / 10 min, Acryft WH206-F (product name) manufactured by Sumitomo Chemical Co., Ltd.) (B1-3) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 10% by mass, melt flow rate: 7 g / 10 min, Acryft WH301-F (product name) manufactured by Sumitomo Chemical Co., Ltd.) (B1-4) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 5% by mass, melt flow rate: 2 g / 10 min, Acryft WD203-1 (trade name) manufactured by Sumitomo Chemical Co., Ltd.) (B1-5) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 24% by mass, melt flow rate: 2 g / 10 min, Lotril 24MA02N (trade name) manufactured by Arkema) (B1-6) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 20% by mass, melt flow rate: 8 g / 10 min, Rotader 4503 (trade name) manufactured by Arkema) (B1-7) Ethylene / butyl acrylate copolymer (butyl acrylate content: 17% by mass, melt flow rate: 7 g / 10 min, Lotril 17BA07N (trade name) manufactured by Arkema) (B1-8) Ethylene / ethyl acrylate copolymer (ethyl acrylate content: 20% by mass, melt flow rate: 20 g / 10 min, DPDJ-9169 (trade name) manufactured by The Dow Chemical Company) (B1-9) Ethylene / ethyl acrylate copolymer (ethyl acrylate content: 7% by mass, melt flow rate: 4 g / 10 min, NUC-6220 (trade name) manufactured by The Dow Chemical Company) (B1-10) Ethylene / methacrylic acid copolymer (methacrylic acid content: 10% by mass, melt flow rate: 35 g / 10 min, Nuclell N1035 (trade name) manufactured by Mitsui Dow Chemical Co.) (B1-11) Ethylene / acrylic acid copolymer (acrylic acid content: 10% by mass, melt flow rate: 30 g / 10 min, Escor 5080 (trade name) manufactured by Exxon Mobil Corporation)

[0070] (B2) Component: "Copolymer of ethylene and a (meth)acrylic acid derivative" that does not fall under (B1) (B2-1) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 32% by mass, melt flow rate: 450 g / 10 min, Acryft CM5022 (trade name) manufactured by Sumitomo Chemical Co., Ltd.) (B2-2) Ethylene / methyl methacrylate copolymer (methyl methacrylate content: 28% by mass, melt flow rate: 150 g / 10 min, Acryft CM5023 (trade name) manufactured by Sumitomo Chemical Co., Ltd.) (B2-3) Ethylene / butyl acrylate copolymer (butyl acrylate content: 35% by mass, melt flow rate: 320 g / 10 min, Lotril 35BA320 (trade name) manufactured by Arkema) (B2-4) Ethylene / butyl acrylate copolymer (butyl acrylate content: 35% by mass, melt flow rate: 40 g / 10 min, Lotril 35BA40 (trade name) manufactured by Arkema) (B2-5) Ethylene / butyl acrylate copolymer (butyl acrylate content: 28% by mass, melt flow rate: 175 g / 10 min, Lotril 28BA175 (trade name) manufactured by Arkema)

[0071] (C) Tackifying resin (C1) Partially hydrogenated tackifying resin (C1-1) Hydrogenated alicyclic / aromatic copolymer hydrocarbon resin (softening point: 103°C, T-REZ HC103 (trade name) manufactured by Eneos Corporation) (C2) Fully hydrogenated tackifying resin (C2-1) Hydrogenated alicyclic hydrocarbon resin (softening point: 103°C, T-REZ HA103 (trade name) manufactured by Eneos Corporation) (C2-2) Hydrogenated alicyclic hydrocarbon resin (softening point: 125°C, T-REZ HA125 (trade name) manufactured by Eneos Corporation) (C2-3) Hydrogenated alicyclic hydrocarbon resin (softening point: 125°C, Imerv P125 (trade name) manufactured by Idemitsu Oil Co., Ltd.)

[0072] (D) Wax (D1) Fischer-Tropsch wax (melting point: 108°C, penetration: 2, Sasol H1 (trade name) manufactured by Sasol Corporation) (D2) Fischer-Tropsch wax (melting point: 112°C, penetration: 2, Sasol C105 (trade name) manufactured by Sasol Corporation) (D3) Paraffin wax (melting point: 69°C, penetration: 12, Paraffin 155F (trade name) manufactured by Nippon Seiro Co., Ltd.) (D4) Microcrystalline wax (melting point: 84°C, penetration: 12, Himic 1080 (trade name) manufactured by Nippon Seiro Co., Ltd.) (D5) Polyethylene wax (melting point: 109°C, penetration: 7, Hiwax 320P (product name) manufactured by Mitsui Chemicals) (D6) Polypropylene wax (melting point: 140 to 148°C, penetration: 1 or less, Hiwax NP105 (trade name) manufactured by Mitsui Chemicals, Inc.)

[0073] (E) Stabilizer (E1) Phenolic antioxidant (ADEKA STAB AO-60 (trade name) manufactured by ADEKA Corporation) (E2) Phosphorus-based antioxidant (JP650 manufactured by Johoku Chemical Co., Ltd.) (E3) Sulfur-based antioxidant (Sumilizer TPS manufactured by Sumitomo Chemical Co., Ltd.)

[0074] The above-mentioned components were melt-mixed in the proportions (parts by mass) shown in Tables 1 and 2. Using a universal mixer, the components were melt-mixed at about 145°C for about 1 hour to produce the hot melt adhesives of Examples 1 to 14 and Comparative Examples 1 to 6. The hot melt adhesives of the Examples and Comparative Examples were evaluated for adhesion, thermal stability, setting ability, and stringiness using the methods described below. To evaluate adhesion, a sample was obtained by applying hot melt adhesive to a piece of K-liner cardboard and pasting it with another piece of K-liner cardboard. To evaluate thermal stability, the hot melt adhesive was stored in an atmosphere at 150°C for one week (168 hours) and the rate of viscosity change and the occurrence of char were checked. To evaluate setting ability, samples were prepared using various pressure times and then a peel test was conducted. To evaluate stringiness, the state of the hot melt adhesive being dispensed was checked under conditions of 180°C. An overview of each evaluation is provided below.

[0075] <Adhesiveness> (Sample production) Hot melt adhesive melted at 180°C was applied to K-liner cardboard at a coating rate of 2g / m, and after an open time of 3 seconds, the adhesive was pressed under a pressure of 1kg / 25cm. 2 The adhesive was then attached to another sheet of K-liner cardboard, with a setting time (pressure time) of 10 seconds, to prepare a sample. At least three samples were prepared for each hot melt adhesive. (Evaluation method) The prepared samples were cured for 24 hours in a thermostatic chamber set at 60°C, 23°C, or -10°C. After that, they were forcibly peeled off by hand in that atmosphere. The percentage of the K-liner cardboard that was broken out of the total adhesive area was defined as the material breakage rate (the percentage of material that was broken), and the condition of the adhesive surface of the K-liner cardboard was evaluated. The evaluation criteria are as follows: ◎: Material failure rate is higher than 80% ○: Material failure rate is 60% to 80% △: Material failure rate is 40% or more but less than 60% ×: Material failure rate is less than 40%

[0076] <Thermal stability> (Sample production) 50 g of each hot melt adhesive was placed in a 100 cc glass bottle, which was then stored in a 150° C. thermostatic chamber for 168 hours to prepare a sample. (Evaluation method) The hot melt adhesive samples stored in a 150°C thermostatic chamber for 168 hours were visually inspected to check for the presence or absence of charring, the state of separation of the hot melt adhesive, etc. The evaluation criteria were as follows: Generation of carbides ◎: No carbide ○: Slight carbide △: Carbide present ×: Significant carbides Separated state ◎: No sediment ○: There is a small amount of sediment △: Carbide present ×: Significant sedimentation

[0077] <Setting> (Sample production) Hot melt adhesive melted at 180°C is applied to K-liner cardboard at a coating rate of 2g / m, and after an open time of 3 seconds, the adhesive is pressed under a pressure of 1kg / 25cm. 2 Then, we changed the setting time (pressure time) and stuck it together with another piece of K-liner cardboard to create samples. (Evaluation method) The prepared sample was immediately subjected to forced peeling in the vertical direction (at 90°) at a constant speed using a Kanebo Tester (product name) manufactured by MEC Co., Ltd., and the peel strength was measured. Furthermore, the state of the K-liner cardboard after peeling was visually observed. The shortest time required for the peel strength to be 6 kgf / cm or more and for the K-liner cardboard to break (breakage rate: 40% or more) was recorded as the set time. The evaluation criteria were as follows: ◎: Set time is less than 1.0 seconds ○: Set time is 1.0 to 1.5 seconds ×: Set time is longer than 1.5 seconds

[0078] <Reduced stringiness> The hot melt adhesive was intermittently applied vertically to the adherend 20 cm away from the tip of the hot melt gun. The state of any material that fell between the hot melt gun and the adherend was visually observed to evaluate stringiness. (Measurement conditions) Temperature setting: Tank, hose, and nozzle all 180℃ Nozzle diameter: 14 / 1000 inches Nozzle: 4 orifices (number of outlets: 4) Dispensing pressure: 0.3MPa Number of spray shots: 180 shots / minute for each of the four orifices The evaluation criteria are as follows: ◎: The shape of the falling object is granular ○: Most of the falling material is granular, with a small amount of thread-like material mixed in. △: The shape of the falling objects is a mixture of granular and string-like. ×: The falling object is thread-like

[0079] [Table 1]

[0080] [Table 2]

[0081] As shown in Tables 1 and 2, the hot melt adhesives of Examples 1 to 14 contain (A) an ethylene / olefin copolymer having 3 to 20 carbon atoms, (B1) an ethylene / (meth)acrylic acid ester copolymer having a melt flow rate of 1 to 38 g / 10 min, and (C) a tackifier resin, and therefore have an excellent overall balance of adhesiveness, thermal stability, setting ability, and stringiness.

[0082] In particular, the hot melt adhesives of Examples 1 to 3 have improved thermal stability while reducing stringiness to a higher level. The hot melt adhesives of the Examples are useful in the paper processing field, particularly for application to cardboard such as corrugated cardboard and cartons.

[0083] In contrast, as shown in Table 2, the hot melt adhesives of Comparative Examples 1 to 6 do not contain component (B1), and therefore are significantly inferior in any of the performances of adhesiveness, thermal stability, and stringiness reduction. [Industrial Applicability]

[0084] The present invention can provide a hot melt adhesive and a paper product coated with the hot melt adhesive. The paper product according to the present invention is particularly effective for products made from thick paper such as cardboard and cartons.

Claims

1. (A) an ethylene / C3-C20 olefin copolymer, (B) a copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond, (C) a tackifying resin, and (D) a wax; The ethylene / C3-C20 olefin copolymer (A) is contained in an amount of 25 to 60 parts by mass per 100 parts by mass of the total of (A) to (C), (A) the ethylene / C3-C20 olefin copolymer includes a metallocene-based ethylene / C3-C20 olefin copolymer; The metallocene-based ethylene / C3-C20 olefin copolymer is selected from a copolymer of ethylene and octene, a copolymer of ethylene and propylene, and a copolymer of ethylene and hexene; (B) the copolymer of ethylene and a carboxylic acid derivative having an ethylenic double bond includes (B1) a copolymer of ethylene and a (meth)acrylic acid derivative having a melt flow rate of 1 to 38 g / 10 min, (B1) is selected from ethylene / methyl methacrylate copolymers and ethylene / butyl acrylate copolymers; (B1) a copolymer of ethylene and a (meth)acrylic acid derivative is contained in an amount of 1 to 10 parts by mass per 100 parts by mass of the total of (A) to (C), (D) The wax comprises a Fischer-Tropsch wax having a melting point of 108 to 112°C. Hot melt adhesive.

2. 2. The hot melt adhesive according to claim 1, wherein the metallocene-based ethylene / C3-C20 olefin copolymer is a copolymer of metallocene-based ethylene and octene.

3. 3. The hot melt adhesive according to claim 1, wherein the metallocene-based ethylene and octene copolymer is contained in an amount of 25 to 60 parts by mass per 100 parts by mass of the total of (A) to (C).

4. A paper product comprising the hot melt adhesive according to any one of claims 1 to 3.

Images