JP2019178346A - Hot melt adhesive - Google Patents

Abstract

To provide a hot melt adhesive which prevents load collapse of stacked fiberboard boxes, does not damage a fiberboard base material, and is excellent in coating properties and stringiness.SOLUTION: A hot melt adhesive contains (A) amorphous poly-α-olefin, (B) crystalline poly-α-olefin obtained by polymerization of α-olefin with a metallocene catalyst, and (C) a tackifying resin; contains 5-30 pts.wt. of the (C) with respect to 100 pts.wt. of the total weight of the (A) to the (C); and has a melt viscosity at 180°C of 3,000 mPa s or less.SELECTED DRAWING: None

Description

  The present invention relates to a hot melt adhesive. Specifically, the present invention relates to a hot melt adhesive applied to a corrugated cardboard and a corrugated cardboard on which a coating film of the hot melt adhesive is formed.

  Hot melt adhesives are solvent-free adhesives and are used in a wide range of fields such as paper processing, woodworking, sanitary materials, and electronics. After the hot melt adhesive is heated and melted and applied to one adherend, it is brought into contact with the other adherend and cooled and solidified, thereby exhibiting adhesiveness.

  As a base polymer of a hot melt adhesive, for example, an ethylene-vinyl acetate copolymer (hereinafter also referred to as “EVA”) or an ethylene-ethyl acrylate copolymer (hereinafter also referred to as “EEA”), depending on the application. Ethylene copolymers such as polyethylene, polypropylene, amorphous poly α-olefin (hereinafter also referred to as “APAO”), styrene block copolymers (for example, styrene-isoprene-styrene) Synthetic rubbers such as block copolymers (hereinafter also referred to as “SIS”), styrene-butadiene-styrene block copolymers (hereinafter also referred to as “SBS”) and hydrogenated products thereof, and polyurethane are widely used.

  Among these hot melt adhesives, some hot melt adhesives based on amorphous poly-α-olefin (APAO) have excellent adhesion to corrugated cardboard in the heated and melted state, and corrugated cardboard processing. (See Patent Documents 1 to 3). The corrugated cardboard is a sheet in which a paperboard liner is pasted on one or both sides of a shin formed by corrugating paperboard. The paperboard used for the liner includes a kraft liner (K liner) using kraft pulp and waste paper as raw materials, and a jute liner (C liner) using waste paper as a raw material. A typical example of corrugated cardboard includes exterior corrugated cardboard described in JIS 1516.

  The hot melt adhesive for corrugated cardboard can be used as a non-slip member for corrugated cardboard in addition to processing corrugated cardboard. Corrugated cardboard surfaces are smooth and slippery. A plurality of cardboard boxes stacked, for example, collapse when they are slightly tilted during movement, and the handling is very high and the work efficiency is low.

  When stacking multiple cardboard boxes, if a hot melt adhesive film is formed on the surface of the cardboard, the hot melt adhesive film stops slipping on the cardboard surface, and the load collapses even if it is tilted. Disappear. The coating film of the hot melt adhesive is formed, for example, by heating and melting the hot melt adhesive and applying it to the surface of the cardboard, and cooling and solidifying the coating layer. As a result of preventing the collapse of the load obtained by stacking a plurality of cardboard boxes, the safety when handling the load is improved, and it is easy to move in the stacked state, so that the work efficiency is also improved.

  When stacking cardboard boxes on the hot melt adhesive coating as described above, if the cooled and solidified hot melt adhesive still has adhesiveness to the cardboard, the stacked cardboards will stick strongly together. When the cardboard is unloaded, the substrate may be damaged.

  Therefore, it is desired that the hot-melt adhesive for corrugated cardboard has two performances of stopping slippage between the corrugated cardboards and not adhering to the corrugated cardboard in a cooled and solidified state. However, Patent Documents 1 to 3 do not describe a hot-melt adhesive having these two performances.

  The hot melt adhesive of Patent Document 1 contains syndiotactic polypropylene and amorphous poly-α-olefin ([Claim 1], [Claim 9] and "Tables 1 and 2"). The cardboard is sealed with a hot melt adhesive as described in [0070] and [FIG. 3]. As described above, there is no description in Document 1 regarding the collapse of the cardboard box. Furthermore, in order to prevent collapse of the stacked cardboard boxes, fine conditions are required for the application width of the hot melt adhesive, the dots, and the like. The hot melt adhesive of Document 1 cannot be said to have good applicability to the extent that the above-mentioned fine conditions are satisfied.

  Patent Document 2 discloses a hot melt adhesive containing a metallocene polyolefin and an amorphous poly-α-olefin as a base polymer and containing a functional polyolefin (maleated polyethylene or maleated polypropylene) to improve heat resistance. ([Claims]). The hot melt adhesive of Document 2 was developed for packaging (see [0002] [0003] [0047] [0051]), and the hot melt adhesive of Document 2 is used to prevent the cardboard box from collapsing. If the agent is used, the corrugated board base material is damaged.

  Patent Document 3 describes a hot melt adhesive containing an ethylene-α-olefin copolymer ([Claim 1]). The hot melt adhesive of Document 3 has excellent heat and cold resistance ([0001]), and is used for producing paper packaging materials such as cardboard boxes ([Claim 6], [0038]). . The hot melt adhesive of Document 3 cannot be used to prevent the cardboard box from collapsing because the adhesive strength is too strong and the corrugated board substrate may be damaged.

  In recent years, hot melt adhesives are required to have various performances by users.

  When applying the hot melt adhesive, a thread-like material of the hot melt adhesive may be generated between the tip of the nozzle and the adherend. This thread-like material is caused by the stringiness of the hot melt adhesive, and stains the nozzle and adherend. Therefore, the development of hot melt adhesives with less stringing has become an important responsibility for adhesive manufacturers, and the demand for stringing is particularly severe for users who handle cardboard and cardboard. It cannot be said that the hot melt adhesives of Literatures 1 to 3 sufficiently satisfy the high user performance requirements.

JP 2005-505679 Gazette Special table 2011-511866 gazette JP 2014-208812 A

  The present invention has been made to solve the above-mentioned problems, prevents the collapse of the stacked cardboard boxes, does not damage the corrugated cardboard base material, and further improves coatability and stringability. Another object of the present invention is to provide an excellent hot melt adhesive. It is another object of the present invention to provide a corrugated cardboard on which a coating film of the hot melt adhesive is formed.

  As a result of intensive investigations, the present inventors have blended amorphous poly α-olefin with crystalline poly α-olefin having a narrow molecular weight distribution, and the amount of tackifying resin and the melt viscosity are specified, and the results are accumulated. In order to complete the present invention, it has been found that a hot melt adhesive that prevents collapse of the corrugated cardboard box and that does not damage the corrugated cardboard substrate and that is excellent in applicability and stringiness can be obtained. It came.

That is, the present invention includes (A) an amorphous polyα-olefin, (B) a crystalline polyα-olefin obtained by polymerizing an α-olefin with a metallocene catalyst, and (C) a tackifying resin.
5 to 30 parts by weight of (C) is included with respect to 100 parts by weight of the total weight of (A) to (C),
A hot melt adhesive having a melt viscosity at 180 ° C. of 3,000 mPa · s or less is provided.

  In one certain form, (A) an amorphous poly alpha olefin has a chemical structure derived from propylene.

  In one certain form, (A) amorphous poly alpha olefin contains the propylene / ethylene / 1-butene copolymer.

  In one certain form, (A) amorphous poly (alpha) -olefin further contains the polypropylene homopolymer.

  In one certain form, (B) crystalline poly alpha olefin contains the polypropylene homopolymer.

  In addition, the present invention provides any one of the above hot melt adhesives applied to cardboard.

  The present invention also provides a cardboard on which a coating film of any of the above hot melt adhesives is formed.

The hot melt adhesive of the present invention comprises (A) an amorphous poly α-olefin, (B) a crystalline poly α-olefin obtained by polymerizing α-olefin with a metallocene catalyst, and (C) a tackifying resin. And (C) is contained in an amount of 5 to 30 parts by weight with respect to a total weight of 100 parts by weight of (A) to (C), and the melt viscosity at 180 ° C. is 3,000 mPa · s or less,
The stacked cardboard boxes are prevented from collapsing, the corrugated board base material is not damaged, and the coating property and the stringing property are excellent.

  When the coating film of the hot melt adhesive of the present invention is formed on the corrugated cardboard surface, the stacked corrugated cardboard does not collapse, and when the operator unloads the corrugated cardboard, the corrugated cardboard base material is damaged. hard. That is, the present invention can provide a hot melt adhesive that prevents the cardboard box from collapsing and also prevents damage to the corrugated board substrate.

  The hot melt adhesive of the present invention comprises (A) an amorphous poly α-olefin, (B) a crystalline poly α-olefin obtained by polymerizing α-olefin with a metallocene catalyst, and (C) a tackifying resin. Is included.

<(A) Amorphous poly α-olefin>
In the present invention, “(A) amorphous poly α-olefin (hereinafter, also referred to as“ component (A) ”)” is a polymer of amorphous α-olefin, This is called crystalline poly α-olefin. As long as the hot melt adhesive according to the present invention can be obtained, (A) the amorphous poly α-olefin is not particularly limited.

  Here, “amorphous” usually means that it is not crystalline, but more specifically, it means a state in which polymer molecular chains are irregularly arranged. (A) By mix | blending amorphous poly (alpha) -olefin with a hot-melt-adhesive, a hot-melt-adhesive becomes a thing with a high friction coefficient, and becomes a thing which is hard to slip on the to-be-adhered body (corrugated cardboard) surface.

  Friction is a force that acts in a direction to block this movement at the contact surface when an object tries to move while in contact with the surface of another object or is moving. Friction is a static friction that tries to stop until one object slides out due to the relative motion of the two objects ("maximum static friction force", which is the frictional force when the object is about to slide) , And dynamic friction (sliding friction, rolling friction, etc.) that tries to stop the moving object.

  In this specification, the friction means static friction, and the coefficient of friction means the coefficient of static friction.

  (A) As an amorphous poly α-olefin, for example, amorphous polypropylene, amorphous polyethylene, or a copolymer of amorphous propylene and another α-olefin, and amorphous ethylene And other α-olefin copolymers.

  Specifically, polypropylene (homopolymer), propylene / ethylene copolymer, propylene / 1-butene copolymer, propylene / ethylene / 1-butene terpolymer, propylene / 1-hexene / 1-octene. And a terpolymer of propylene / 1-hexene / methylpentene, 1-polybutene (homopolymer), and the like.

  In the present invention, (A) the amorphous polyα-olefin preferably has a chemical structure derived from propylene. The chemical structure derived from propylene is meant to include both pure propylene and propylene derivatives having other functional groups. When the hot melt adhesive of the present invention contains a chemical structure derived from propylene, the maximum static frictional force becomes large and it becomes difficult to slip, so that the cardboard box can be prevented from collapsing, and the corrugated board base material is damaged. Can also be prevented.

  (A) The amorphous poly α-olefin is contained in an amount of 20 to 90 parts by weight, preferably 39 to 83 parts by weight, more preferably 100 parts by weight of the total weight of (A) to (C). Is contained in an amount of 45 to 75 parts by weight.

  (A) Propylene / ethylene / 1-butene is mentioned as a preferable form of the amorphous poly α-olefin. By blending propylene / ethylene / 1-butene, it is possible to reliably prevent the collapse of the loaded cardboard boxes and at the same time to prevent damage to the cardboard substrate.

  (A) It is particularly preferable that the amorphous poly α-olefin further contains a polypropylene homopolymer. By including polypropylene, the hot melt adhesive can more reliably prevent the cardboard box from collapsing, and can reliably prevent damage to the corrugated board substrate.

In the present invention, (A) the density of the amorphous poly-α- olefin is preferably from 1.00 g / cm ³ or ^less, particularly preferably ^{0.80g / cm 3 ~0.90g / cm 3} , 0.85g / cm ^{3 to} 0.88 g / cm ³ is most preferable. (A) When the density of the amorphous poly α-olefin is in the above range, the hot melt adhesive of the present invention becomes less slippery and can more reliably prevent the cardboard box from collapsing.

<(B) Crystalline poly α-olefin obtained by polymerizing α-olefin with metallocene catalyst>
In the present invention, “(B) crystalline polyα-olefin obtained by polymerizing α-olefin with a metallocene catalyst (hereinafter also referred to as“ (B) crystalline polyα-olefin ”or“ (B) component ””. ")" Indicates a crystalline α-olefin polymer produced using a metallocene catalyst as a polymerization catalyst. Here, “crystallinity” means what is usually called “crystallinity”, and more specifically refers to a state in which polymers are regularly arranged.

  The hot melt adhesive of the present invention contains (B) crystalline poly-α-olefin, thereby making it difficult to damage the corrugated board substrate when unloading the cardboard.

  (B) The crystalline poly α-olefin is contained in an amount of 5 to 50 parts by weight, preferably 10 to 45 parts by weight, more preferably 100 parts by weight of the total weight of (A) to (C). 25 to 40 parts by weight are included.

  (B) As crystalline poly α-olefin, for example, polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, ethylene / propylene / α-olefin copolymer Examples thereof include a polymer, an ethylene / 1-butene copolymer, a propylene / 1-butene copolymer, and an ethylene / propylene / 1-butene copolymer.

  In this invention, it is preferable that (B) crystalline poly alpha olefin contains polypropylene. (B) Component containing polypropylene improves compatibility between component (B) and component (A), and the hot-melt adhesive maintains damage prevention on the corrugated cardboard surface while ensuring damage to the corrugated cardboard substrate. Can be prevented.

  When an α-olefin is polymerized using a metallocene catalyst, a polymer having a very narrow molecular weight distribution is synthesized. Therefore, there is no bias in the crystallinity of the poly-α-olefin, and a uniform polymer can be obtained with respect to the molecular structure: for example, the arrangement of propylene sites and other structural units; the content ratio of each structural unit; Therefore, the possibility of producing a low molecular weight substance that causes a decrease in adhesion is reduced, and it is difficult to cause a decrease in adhesion.

(B) a density of crystalline poly α- olefins, 0.7 g / cm ³ or ^more, particularly preferably ^{0.80g / cm 3 ~0.10g / cm 3} , 0.86g / cm 3 ~0.90g / Cm ³ is most preferred.

<(C) Tackifying resin>
“(C) Tackifying resin” is usually used in hot melt adhesives, and can be particularly limited as long as the hot melt adhesive intended by the present invention can be obtained. Absent.

  (C) The tackifying resin is contained in an amount of 5 to 30 parts by weight, preferably 6 to 25 parts by weight, more preferably 7 to 20 parts per 100 parts by weight of the total weight of (A) to (C). Part by weight is included.

  In the hot melt adhesive, (C) the tackifying resin is contained in the above ratio, so that the coefficient of friction is kept high to prevent slipping on the surface of the corrugated cardboard. Damage can also be prevented.

  Examples of tackifying resins include natural rosin, modified rosin, hydrogenated rosin, natural rosin glycerol ester, modified rosin glycerol ester, natural rosin pentaerythritol ester, modified rosin pentaerythritol ester, hydrogenated rosin pentaerythritol ester. , Natural terpene copolymer, natural terpene three-dimensional polymer, hydrogenated terpene copolymer hydrogenated derivative, polyterpene resin, phenolic modified terpene resin hydrogenated derivative, aliphatic petroleum hydrocarbon resin, aliphatic petroleum hydrocarbon resin Examples include hydrogenated derivatives, 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. The tackifying resin may be a liquid type tackifying resin as long as the color tone is colorless to light yellow and has substantially no odor and good thermal stability. Considering these characteristics comprehensively, hydrogenated derivatives such as the above-mentioned resins are preferable as the tackifier resin.

  (C) As a tackifier resin, a commercial item can be used. Examples of such commercially available products include ECR231C (trade name), ECR179EX (trade name), ECR5600 (trade name) manufactured by ExxonMobil, Maruka Clear H (trade name) manufactured by Maruzen Petrochemical Co., and Clearon manufactured by Yashara Chemical Co., Ltd. K100 (trade name), Clearon K4090 (trade name) and Clearon K4100 (trade name) and Clearon P105 (trade name), Alcon M100 (trade name), Alcon P90 (trade name) manufactured by Arakawa Chemical Co., Ltd., Idemitsu Petrochemical Co., Ltd. Examples include Imabu S100 (trade name), Imabe Y135 (trade name), Imabe P125 (trade name) and Imabe P100 (trade name), and Rigalite R7100 (trade name) manufactured by Eastman Chemical Co., Ltd. These commercially available tackifying resins can be used alone or in combination.

  The hot melt adhesive of the present invention comprises (A) component to (C) component, and has a melt viscosity at 180 ° C. of 3,000 mPa · s or less, preferably 200 to 2,500 mPa · s, particularly Most preferably, it is 800 to 2,000 mPa · s. When the melt viscosity is in the above range, the hot melt adhesive is excellent in applicability and can further reduce stringing.

  In this specification, the melt viscosity at 180 ° C. means a value measured using a No. 27 rotor and using a Brookfield viscometer and a thermocell.

  In the present invention, the hot melt adhesive preferably further contains a wax. In the present specification, the term “wax” refers to an organic substance having a weight average molecular weight of less than 10,000, which is solid at room temperature and becomes liquid when heated, and generally referred to as “wax”. As long as the hot melt adhesive according to the present invention can be obtained, it is not particularly limited. The wax can be a synthetic wax or a natural wax.

  Examples of the synthetic wax include Fischer-Tropsch wax, polyolefin wax (for example, polyethylene wax, polypropylene wax, polyethylene / polypropylene wax).

  “Fischer-Tropsch wax” refers to what is synthesized by the Fischer-Tropsch method and is generally made into Fischer-Tropsch wax. Fischer-Tropsch wax is obtained by separating wax from component wax having a relatively wide carbon number distribution so that component molecules have a narrow carbon number distribution.

  As Fischer-Tropsch wax, Sazol H1 (trade name), Sazol C80 (trade name) manufactured by Sazol Wax, and FT-115 (trade name) manufactured by Nippon Seiwa Co., Ltd. are commercially available.

  Examples of natural waxes include paraffin wax, microcristan wax, and petrolatum.

  Paraffin wax is a wax that is solid at room temperature and is separated from vacuum-distilled extracted oil. As a typical paraffin wax, Paraffin Wax series manufactured by Nippon Seiwa Co., Ltd. may be mentioned.

  The microcrystalline wax is a wax that is solid at room temperature and separated from a vacuum distillation bottom or heavy extracted oil. As a typical microcrystalline wax, Hi-Mic series manufactured by Nippon Seiwa Co., Ltd. can be mentioned.

  Petrolatum is a wax that is semi-solid at room temperature and separated from a vacuum distillation bottom. A typical petrolatum is Centon CP series manufactured by Chuo Yuka.

  The hot melt adhesive of the present invention preferably contains “paraffin wax” which is a natural wax. When the paraffin wax is blended, the hot melt adhesive of the present invention improves the cohesive force and becomes hard, so that the cardboard base material can be prevented from being damaged when the cardboard load is released.

  The hot melt adhesive of the present invention preferably contains a plasticizer. “Plasticizer” is blended for the purpose of lowering the melt viscosity of hot melt adhesives, imparting flexibility, and improving wettability to the adherend, and is compatible with the ethylene-based copolymer. There is no particular limitation as long as a melt adhesive can be obtained. Examples of the plasticizer include paraffinic oil, naphthenic oil, and aromatic oil. Colorless and odorless paraffinic oil is particularly preferred.

  When paraffinic oil is blended, the hot melt adhesive of the present invention is imparted with flexibility, so that slipperiness on the corrugated cardboard surface can be prevented, stringing can be reduced, and coatability is improved.

  A commercial item can be used as a plasticizer. For example, White Oil Broom 350 (trade name) manufactured by Kukdong Oil & Chem, Diana Fresia S32 (trade name), Diana Process Oil PW-90 (trade name), DN Oil KP-68 (trade name), BP manufactured by Idemitsu Kosan Co., Ltd. Examples include Energyr M1930 (trade name) manufactured by Chemicals, Kaydol (trade name) manufactured by Crompton, and Primol 352 (trade name) manufactured by Esso. These plasticizers can be used alone or in combination.

  The hot melt adhesive according to the present invention may further contain various additives as necessary. Examples of such various additives include stabilizers (ultraviolet absorbers, antioxidants) and fine particle fillers.

  "Stabilizer" is formulated to improve the stability of hot melt adhesives by preventing the decrease in molecular weight, gelation, coloring, odor generation, etc. caused by heat, air and light. As long as the hot melt adhesive targeted by the present invention can be obtained, the present invention is not particularly limited. Examples of the stabilizer include an antioxidant and an ultraviolet absorber.

  “Ultraviolet absorbers” are used to improve the light resistance of hot melt adhesives. “Antioxidants” are used to prevent oxidative degradation of hot melt adhesives. Antioxidants and ultraviolet absorbers are generally used in hot melt adhesives, and are not particularly limited as long as they can obtain the intended paper product to be described later.

  Examples of the “antioxidant” include a phenol-based antioxidant, a sulfur-based antioxidant, and a phosphorus-based antioxidant. Examples of ultraviolet absorbers include benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers. Furthermore, a lactone stabilizer can also be added. These can be used alone or in combination.

  A commercial item can be used as a stabilizer. For example, 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) manufactured by BASF Japan Ltd. ), Irgafos 168 (trade name) and Irganox 1520 (trade name), ADEKA Adeka Stub AO-60 (trade name), Johoku Chemical Co., Ltd. JF77 (trade name), JP-650 (trade name) Can do. These stabilizers can be used alone or in combination.

  The hot melt adhesive of the present invention can further contain a fine particle filler. The fine particle filler is not particularly limited as long as it is a commonly used one, and the hot melt adhesive targeted by the present invention can be obtained. Examples of the “fine particle filler” include mica, calcium carbonate, kaolin, talc, titanium oxide, diatomaceous earth, urea resin, styrene beads, calcined clay, starch and the like. These shapes are preferably spherical, and the dimensions (diameter in the case of a spherical shape) are not particularly limited.

  The hot melt adhesive according to the present invention is obtained by using a generally known method for producing a hot melt adhesive. (A) Amorphous poly α-olefin, (B) Crystalline poly α-olefin, ( C) Manufactured by blending a tackifier resin and, if necessary, a plasticizer, a wax and the above-mentioned various additives.

  For example, it can be manufactured by blending a predetermined amount of the above-mentioned components and heating and melting them. As long as the desired hot melt adhesive can be obtained, the order of adding the components, the heating method, and the like are not particularly limited.

  In one embodiment of the present invention, a hot melt adhesive is applied to the surface of the corrugated cardboard, cooled and solidified to form a coating film of the hot melt adhesive on the corrugated cardboard surface.

  The method for applying the hot melt adhesive is not particularly limited as long as the object of the present invention can be achieved, but hot melt applicators are widely used. Examples of the hot melt applicator include Pro Blue P4 melter (trade name), Pro Blue P10 melter (trade name) manufactured by Nordson Corporation.

  The application method is roughly classified into, for example, contact application and non-contact application. “Contact application” refers to an application method in which an ejector is brought into contact with a member or a film when hot melt adhesive is applied. “Non-contact application” refers to an ejector that is applied when hot melt adhesive is applied. The coating method which does not contact a member or a film. Examples of contact coating methods include slot coater coating and roll coater coating, and non-contact coating methods include, for example, spiral coating that can be applied in a spiral manner, omega coating that can be applied in a wave shape, control seam coating, and surface coating. Examples thereof include slot spray coating, curtain spray coating, dot coating that can be applied in the form of dots, and bead coating that can be applied in the form of lines.

  When applying the hot melt adhesive of the present invention with a hot melt applicator (even when the hot melt adhesive is discharged and applied in the horizontal direction with the hot melt applicator), stringing the hot melt adhesive Is almost gone. Therefore, the adherend and the applicator are not soiled by the thread.

  Although the application quantity of a hot-melt-adhesive is not specifically limited, For example, it is 1-5 g / m. Moreover, what is necessary is just to determine the application pattern of a hot-melt-adhesive suitably, For example, it is a bead shape.

  The hot melt adhesive coating film (after solidification) formed on the corrugated cardboard surface has a large frictional force against the corrugated cardboard. As a result, even when the cardboard boxes are moved or tilted on the hot melt adhesive coating film, the collapse of the load can be prevented. The coating film of the hot melt adhesive preferably has a static friction coefficient with respect to the surface of the cardboard of 14 or more, more preferably 16.5 or more, and still more preferably 18 or more.

  Also, the hot melt adhesive coating (after solidification) has low adhesion to cardboard. As a result, even when the cardboard boxes are stacked and stored on the hot melt adhesive coating film, the corrugated board substrate is prevented from being damaged at the portion in contact with the adhesive coating film.

  The hot melt adhesive according to the present invention is widely used, for example, for electronic parts, woodwork, building materials, sanitary materials, paper products, etc., but is suitable for stacking and storing a plurality of cardboards.

  INDUSTRIAL APPLICABILITY The present invention is particularly useful as a “corrugated hot melt adhesive” that prevents collapse of stacked cardboard boxes, does not damage the cardboard base material, and is excellent in coating properties and stringing reduction. It is.

  The corrugated cardboard according to the present invention is a corrugated cardboard obtained using the above-mentioned hot melt adhesive. As an aspect of the present invention, a corrugated cardboard having a hot melt adhesive coating film formed on its surface is particularly preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely and in detail, these Examples are only one aspect | mode of this invention, and this invention is not limited at all by these examples. The proportions shown in the examples are based on the weight of the nonvolatile content unless otherwise specified. The components for producing the hot melt adhesive are shown below.

(A) Amorphous poly α-olefin (A1) Amorphous propylene / ethylene / 1-butene copolymer (Vestplast 703 (trade name), manufactured by Evonik, viscosity 2700 mPa · s: 190 ° C., softening point 124 ° C, density 0.87 g / cm ³ )
(A2) Amorphous propylene / ethylene / 1-butene copolymer (Bestplast 704 (trade name), manufactured by Evonik, viscosity 3500 mPa · s: 190 ° C., softening point 105 ° C., density 0.87 g / cm ³ )
(A3) Amorphous propylene / ethylene / 1-butene copolymer (Bestplast 750 (trade name), manufactured by Evonik, viscosity 50000 mPa · s: 190 ° C., softening point 107 ° C., density 0.87 g / cm ³ )
(A4) Amorphous ethylene / propylene copolymer (Rexentac 2304 (trade name), manufactured by Huntsman, viscosity 450 mPa · s: 190 ° C., softening point 141 ° C., density 0.86 g / cm ³ )
(A5) Amorphous propylene homopolymer (East Flex P1010PL (trade name), manufactured by Eastman Chemical Co., Ltd., viscosity 1000 mPa · s: 190 ° C., softening point 155 ° C., density 0.87 g / cm ³ )

(B) Crystalline poly α-olefin obtained by polymerization with a metallocene catalyst (B1) Polypropylene homopolymer (El Modu S400 (trade name), manufactured by Idemitsu Kosan Co., Ltd., MFR 2000 g / 10 min: 230 ° C., density 0.87 g / cm ³ ) Polymer obtained by polymerization with metallocene catalyst (B2) Polypropylene homopolymer (El Modu S600 (trade name), manufactured by Idemitsu Kosan Co., Ltd., MFR 350 g / 10 min: 230 ° C., density 0.87 g / cm ³ ) Polymerization with metallocene catalyst (B3) Polypropylene homopolymer (Lycocene PP6102 (trade name), manufactured by Clariant, viscosity 60 mPa · s: 170 ° C., density 0.90 g / cm ³ ) Polymer obtained by polymerization with a metallocene catalyst (B4) Propylene / ethylene copolymer (Vistama Box 6202 (trade name), manufactured by Exxon Mobil Corporation, MFR20g / 10min: 230 ℃, density 0.86 g / cm ³⁾ polymer obtained by polymerizing with a metallocene catalyst (B5) ethylene / octene copolymer (Affinity GA1900 ( (Trade name), manufactured by Dow Chemical Co., MFR 1000 g / 10 min: 190 ° C., density 0.87 g / cm ³ ) Polymer obtained by polymerization with metallocene catalyst (B′6) polyethylene homopolymer (Petrocene 353 (trade name), Manufactured by Tosoh Corporation, MFR145g / 10min: 190 ° C., density 0.92 g / cm ³ ) Polymer obtained by polymerization with Ziegler-Natta catalyst (B′7) ethylene / polybutene copolymer (DP8911ME (trade name), Basel) Manufactured, MFR 200 g / 10 min: 190 ° C., density 0.90 g / c ³⁾ Ziegler-Natta catalyst with a polymer obtained by polymerizing

(C) Tackifying resin
(C1) Hydrogenated dicyclopentadiene resin (Imabe P100 (trade name), manufactured by Idemitsu Kosan Co., Ltd., softening point 100 ° C.)
(C2) Hydrogenated cycloaliphatic petroleum hydrocarbon resin (Alcon P90 (trade name), manufactured by Arakawa Chemical Industries, softening point 90 ° C.)
(C3) Hydrogenated terpene resin (Clearon P105 (trade name), manufactured by Yasuhara Chemical Co., Ltd., softening point 105 ° C.)

(D) Softener
(D1) Paraffin oil (Diana Fresia S32 (trade name), manufactured by Idemitsu Kosan Co., Ltd.)
(D2) Paraffin oil (Diana Process Oil PW-90 (trade name), manufactured by Idemitsu Kosan Co., Ltd.)
(D3) Naphthenic oil (Sunpure N90 (trade name), manufactured by Japan Sun Oil Co., Ltd.)

(E) Wax
(E1) Paraffin wax (paraffin wax 150 (trade name), manufactured by Nippon Seiwa Co., Ltd.)
(E2) Polyethylene wax (Neowax L (trade name), manufactured by Yasuhara Chemical Co., Ltd.)
(E3) Fischer-Tropsch wax (FT-115 (trade name), manufactured by Nippon Seiwa Co., Ltd.)

(F) Stabilizer
(F1) Antioxidant (Adeka Stub AO-60 (trade name), manufactured by Adeka)

  These components were melt-mixed at a ratio shown in Tables 1, 3, 5 and 7 using a universal stirrer at about 145 ° C. for about 1 hour to prepare hot melt adhesives of Examples and Comparative Examples. These hot melt adhesives are evaluated for melt viscosity, "maximum static friction coefficient" for corrugated board, tilt angle measurement (anti-slip property) and corrugated board base material damage, and stringiness and applicability to confirm workability. Evaluated. The results are shown in Tables 2, 4, 6, and 8.

○ Physical properties and performance evaluation <Viscosity measurement>
Based on the JAI7-11991 B method, the viscosity of each hot melt adhesive was evaluated at 160 ° C. and 180 ° C. For the measurement, a Brookfield viscometer and a No. 27 rotor were used.

<Evaluation of static friction coefficient>
The hot melt adhesives of Examples and Comparative Examples were applied to a 50 μm thick PET film and cooled and solidified to form a 50 μm thick coating film. Thereafter, the PET film was cut into a 40 cm ² square (63 mm × 63 mm) to prepare a sample for obtaining a static friction coefficient.

This sample was affixed from the PET film side to a 200 g weight having a bottom size of 40 cm ² square to form a “slip piece”, and the “slip piece” was placed on the K liner cardboard and pulled at a speed of 100 mm / min. .

  The static friction coefficient of the hot-melt adhesive was determined, and the static friction coefficient was calculated from the initial peak strength of the static friction force (the maximum strength when no clear peak appears). A force gauge (manufactured by Imada Co., Ltd.) was used for the stress measurement.

The formula for calculating the static friction coefficient is shown below.
μ = Fs / Fp
μ: Static friction coefficient Fs: Static friction force (N)
Fp: Normal force generated by the mass of slip deformation (1.96 N)

<Inclination angle measurement>
A hot melt adhesive melted at 180 ° C. was applied in a bead shape to K liner cardboard, cooled and solidified to prepare a lower stage of the sample base material for evaluation, and the lower stage of the sample base material was fixed to a table with a double-sided tape. The length of the coated part was 3 cm, and the coating amount was 3 g / m. After the hot melt adhesive was completely solidified, another K liner cardboard having a weight of 3 kg was placed on the hot melt adhesive coating as the upper stage of the sample substrate. The table was gradually tilted, and the angle when the upper stage of the sample base material slipped was measured. Anti-slip performance (anti-slip property) was evaluated by the size of the tilt angle. The evaluation criteria are as follows.

◎: Inclination angle is 45 degrees or more ○: Inclination angle is 40 degrees or more and less than 45 degrees △: Inclination angle is 35 degrees or more and less than 40 degrees ×: Inclination angle is less than 35 degrees

<Measurement of substrate damage>
About 0.04 g of hot melt adhesive melted at 180 ° C. was applied to the four corners of the K liner cardboard surface with a hand gun.

  After the hot-melt adhesive was completely solidified, another corrugated cardboard was superposed and a 3 kg weight was placed on the corrugated cardboard and placed in an atmosphere of 40 ° C. for 24 hours under a load. Thereafter, the stacked cardboards were peeled by hand, and the substrate damage was evaluated by confirming the state of the cardboards. The evaluation criteria for corrugated substrate damage are shown below.

A: No damage.
○: Slightly fuzzed.
(Triangle | delta): Only 1 point peels among 4 points | pieces.
X: 2 or more points peeled out of 4 points.

○ Evaluation of workability <Evaluation of stringiness>
A hot melt adhesive was intermittently applied vertically to an adherend 20 cm away from the tip of the hot melt gun. The state of the fallen object between the hot melt gun and the adherend was visually observed to evaluate the stringiness. Measurement conditions are as follows.

Temperature setting: Tank temperature, hose temperature, and nozzle temperature are all 180 ° C
Nozzle diameter: 16/1000 inch Nozzle: orifice (number of discharge ports: 1)
Coating pressure: 0.3 MPa
Number of painting shots: 90 shots / 30 seconds

○: There is no threading between the nozzle and the adherend.
(Triangle | delta): A thread may be twisted between a nozzle and a to-be-adhered body.
X: In most cases, the yarn is wound from the nozzle to the adherend, or after discharging, the thread is seen from the drooping of the nozzle.

<Applicability>
About 0.05 g of hot melt adhesive was dropped on the cardboard, and immediately after that, the hot melt adhesive was quickly applied onto the cardboard with a hand coater having a 0.10 mm gap. The applicability was evaluated by confirming the application state of the hot melt adhesive. The evaluation criteria for applicability are shown below.

○: The entire coated portion is uniform.
(Triangle | delta): Only the edge part of an application part is non-uniform | heterogenous.
X: The whole coating part is non-uniform | heterogenous.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Table 7]

[Table 8]

  The present invention provides a hot melt adhesive. The hot melt adhesive according to the present invention is useful as an adhesive for corrugated cardboard, can prevent collapse of the stacked corrugated cardboard boxes, and can prevent damage to the corrugated cardboard substrate.

Claims (7)

(A) amorphous poly α-olefin, (B) crystalline poly α-olefin obtained by polymerizing α-olefin with a metallocene catalyst, and (C) tackifying resin,
5 to 30 parts by weight of (C) is included with respect to 100 parts by weight of the total weight of (A) to (C),
A hot melt adhesive having a melt viscosity at 180 ° C. of 3,000 mPa · s or less.   The hot melt adhesive according to claim 1, wherein (A) the amorphous poly-α-olefin has a chemical structure derived from propylene.   The hot melt adhesive according to claim 1 or 2, wherein (A) the amorphous poly-α-olefin contains a propylene / ethylene / 1-butene copolymer.   The hot melt adhesive according to claim 3, wherein the (A) amorphous poly α-olefin further comprises a polypropylene homopolymer.   (B) The hot melt adhesive according to any one of claims 1 to 4, wherein the crystalline poly-α-olefin contains a polypropylene homopolymer.   The hot melt adhesive according to any one of claims 1 to 5, which is applied to cardboard.   A corrugated cardboard on which a coating film of the hot melt adhesive according to any one of claims 1 to 6 is formed.