JP6970716B2 - Hot melt adhesive - Google Patents

Description

The present invention relates to a hot melt adhesive. More specifically, the present invention relates to a hot melt adhesive applied to 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. Adhesiveness is exhibited by heating and melting the hot melt adhesive, applying it to one adherend, contacting it with the other adherend, and cooling and solidifying it.

As the base polymer of the 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”) may be used depending on the intended use. Ethylene-based copolymers such as, polyethylene, polypropylene, olefin-based resins such as amorphous poly α-olefin (hereinafter, also referred to as “APAO”), styrene-based block copolymers (for example, styrene-isoprene-styrene-based). Block copolymers (hereinafter, also referred to as "SIS"), styrene-butadiene-styrene-based block copolymers (hereinafter, also referred to as "SBS"), synthetic rubbers such as their hydrogenated additives, polyurethane and the like are widely used.

Among these hot-melt adhesives, some hot-melt adhesives based on amorphous poly α-olefin (APAO) have excellent adhesion to corrugated board in a heat-melted state, and are used for processing corrugated board. (Refer to Patent Documents 1 to 3). Corrugated cardboard is a sheet obtained by forming a corrugated paperboard into a corrugated shape and attaching a liner of paperboard to one or both sides of the inner shin. The paperboard used for the liner includes a kraft liner (K liner) made from kraft pulp and waste paper, and a juice liner (C liner) made from waste paper. Typical examples of corrugated cardboard include the exterior corrugated cardboard described in JIS 1516.

The hot melt adhesive for corrugated board can be used as a non-slip member for corrugated board in addition to the processing of corrugated board. The surface of the cardboard is smooth and slippery to each other. For example, a plurality of stacked corrugated cardboard boxes collapses even if they are slightly tilted during movement, and there is a high risk when handling the loaded cardboard, resulting in low work efficiency.

When stacking multiple cardboard boxes, if a coating film of hot melt adhesive is formed on the surface of the cardboard, the coating film of hot melt adhesive will prevent the surface of the cardboard from slipping, and the load will collapse even if it tilts. It disappears. The coating film of the hot melt adhesive is formed, for example, by heating and melting the hot melt adhesive, applying it to the surface of corrugated cardboard, and cooling and solidifying the coating layer. As a result of preventing the load from collapsing the load in which a plurality of cardboard boxes are stacked, the safety when handling the load is improved, and it becomes easier to move in the stacked state, so that the work efficiency is also improved.

When stacking corrugated cardboard boxes on a coating of hot melt adhesive as described above, if the cooled and solidified hot melt adhesive still has adhesiveness to the corrugated cardboard, the stacked corrugated cardboards will strongly adhere to each other. It may be attached and damage to the base material may occur when unloading the corrugated cardboard.

Therefore, it is desired that the hot melt adhesive for corrugated cardboard has two performances of stopping slipping between the stacked corrugated cardboards and not adhering to the corrugated cardboard in the state of being cooled and solidified. 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 a syndiotactic polypropylene and an amorphous poly α-olefin ([Claim 1], [Claim 9] and "Table 1 and Table 2"). The corrugated board is sealed with a hot melt adhesive as described in [0070] and [FIG. 3]. As described above, there is no description about the collapse of the corrugated cardboard box in Document 1. Further, in order to prevent the stacked corrugated cardboard boxes from collapsing, detailed conditions such as the application width and dots of the hot melt adhesive are required. It cannot be said that the hot melt adhesive of Document 1 has good coatability so as to satisfy the above-mentioned fine conditions.

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) in order to improve heat resistance. ([Scope of patent claim]). 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 corrugated cardboard from collapsing. The use of the agent will damage the corrugated board.

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

In recent years, users have demanded various performances from hot melt adhesives.

When applying the hot melt adhesive, a thread 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 thread pulling property of the hot melt adhesive, and stains the nozzle and the adherend. Therefore, the development of hot-melt adhesives with less stringing is an important responsibility for adhesive manufacturers, and users who handle thick paper such as corrugated cardboard and cartons have strict demands for stringing. It cannot be said that the hot melt adhesives of Documents 1 to 3 sufficiently satisfy the high performance required by the user.

Japanese Patent Publication No. 2005-505679 Japanese Patent Publication No. 2011-511866 Japanese Unexamined Patent Publication No. 2014-208812

The present invention has been made to solve the above-mentioned problems, and it prevents the stacked corrugated cardboard boxes from collapsing, does not damage the corrugated cardboard base material, and further improves the coatability and the thread pulling property. Also aimed at providing excellent hot melt adhesives. Further, it is also an object to provide a corrugated cardboard on which a coating film of the hot melt adhesive is formed.

As a result of diligent studies, the present inventors have mixed amorphous poly α-olefins with crystalline poly α-olefins having a narrow molecular weight distribution, and specified the amount of the tackifier resin to be blended and the melt viscosity. We have found that a hot-melt adhesive that prevents the corrugated cardboard box from collapsing, does not damage the corrugated cardboard base material, and has excellent coatability and threading property can be obtained, and completes the present invention. I arrived.

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

In one form, (A) the amorphous poly-α-olefin has a chemical structure derived from propylene.

In one embodiment, (A) the amorphous poly-α-olefin comprises a propylene / ethylene / 1-butene copolymer.

In one form, the (A) amorphous poly-α-olefin further comprises a polypropylene homopolymer.

In one embodiment, (B) the crystalline poly-α-olefin comprises a polypropylene homopolymer.

The present invention also provides any of the above hot melt adhesives to be applied to corrugated board.

The present invention also provides a corrugated 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 an α-olefin with a metallocene catalyst, and (C) a tackifier resin. (A) to (C) contain 5 to 30 parts by weight with respect to 100 parts by weight of the total weight, and the melt viscosity at 180 ° C. is 3,000 mPa · s or less.
It prevents the stacked corrugated cardboard boxes from collapsing, does not damage the corrugated cardboard base material, and is excellent in coatability and stringing property.

When the coating film of the hot melt adhesive of the present invention is formed on the surface of the corrugated cardboard, 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 corrugated cardboard from collapsing and also prevents damage to the corrugated cardboard 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 an α-olefin with a metallocene catalyst, and (C) a tackifier resin. Includes.

<(A) Amorphous poly α-olefin>
In the present invention, the "(A) amorphous poly-α-olefin (hereinafter, also referred to as" (A) component ")" is a polymer of an amorphous α-olefin, and is generally non-crystalline. It is called a crystalline poly-α-olefin. As long as the hot melt adhesive according to the present invention can be obtained, the (A) 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 molecular chains of a polymer are irregularly arranged. (A) By blending the amorphous poly α-olefin with the hot melt adhesive, the hot melt adhesive has a high coefficient of friction and makes the surface of the adherend (corrugated cardboard) less slippery.

Friction is a force acting in a direction that hinders this movement at the contact surface when an object tries to move while touching the surface of another object or when it is moving. Friction is the static friction (“maximum static friction force” which is the frictional force when an object is about to slide) that tries to stop until one object slides due to the relative motion state of two objects. , It is divided into dynamic friction (sliding friction, rolling friction, etc.) that tries to stop a moving object.

In the present specification, the friction is the static friction, and the coefficient of friction means the coefficient of static friction.

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

Specifically, polypropylene (homopolymer), propylene / ethylene copolymer, propylene / 1-butene copolymer, propylene / ethylene / 1-butene ternary copolymer, propylene / 1-hexene / 1-octene. Can be exemplified with the ternary polymer of propylene / 1-hexene / methylpentene, 1-polybutene (homopolymer) and the like.

In the present invention, (A) the amorphous poly α-olefin preferably has a chemical structure derived from propylene. The chemical structure derived from propylene means that it contains both pure propylene and a propylene derivative having another functional group. When the hot melt adhesive of the present invention contains a chemical structure derived from propylene, the maximum static friction force becomes large and it becomes difficult to slip, so that it is possible to prevent the corrugated cardboard box from collapsing and damage the corrugated cardboard substrate. Can also be prevented.

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

(A) Preferred forms of the amorphous poly α-olefin include propylene / ethylene / 1-butene. By blending propylene / ethylene / 1-butene, the stacked corrugated cardboard boxes can be reliably prevented from collapsing, and at the same time, the corrugated cardboard substrate can be prevented from being damaged.

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

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

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

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

(B) Examples of the crystalline poly-α-olefin include polyethylene, polypropylene, an ethylene / propylene copolymer, an ethylene / α-olefin copolymer, a propylene / α-olefin copolymer, and an ethylene / propylene / α-olefin. Examples thereof include polymers, ethylene / 1-butene copolymers, propylene / 1-butene copolymers and ethylene / propylene / 1-butene copolymers.

In the present invention, the (B) crystalline poly-α-olefin preferably contains polypropylene. The inclusion of polypropylene in component (B) improves the compatibility between component (B) and component (A), and the hot melt adhesive ensures damage to the corrugated board while maintaining anti-slip on the corrugated board surface. Can be prevented.

Polymerization of α-olefins using a metallocene catalyst produces polymers with a very narrow molecular weight distribution. Therefore, a uniform polymer can be obtained with respect to the molecular composition: for example, the arrangement of the propylene moiety and other structural units; the content ratio of each structural unit; etc., without causing a bias in the crystallinity of the polyα-olefin. Therefore, it is less likely that a low molecular weight substance that causes a decrease in adhesive strength will be generated, and it is unlikely that the adhesive strength will be reduced.

(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) Adhesive-imparting resin>
The "(C) tackifier resin" is usually used for a hot melt adhesive, and is not particularly limited as long as it can obtain the hot melt adhesive intended by the present invention. No.

The tackifier resin (C) is contained in an amount of 5 to 30 parts by weight, preferably 6 to 25 parts by weight, and more preferably 7 to 20 parts by weight based on 100 parts by weight of the total weights of (A) to (C). Included by weight.

The hot melt adhesive contains (C) the tackifier resin in the above ratio to maintain a high coefficient of friction to prevent slipping on the corrugated cardboard surface, and when the corrugated cardboard is unloaded, the corrugated board base material is used. It can also prevent damage.

Examples of the tackifier resin include natural rosin, modified rosin, hydrocarbon rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, and pentaerythritol ester of hydrocarbon rosin. , Natural terpene copolymers, natural terpene three-dimensional polymers, hydrogenated terpene copolymer hydrides, polyterpene resins, phenolic modified terpene resin hydrides, aliphatic petroleum hydrocarbon resins, aliphatic petroleum hydrocarbon resins Examples thereof include hydrogenation derivatives, aromatic petroleum hydrocarbon resins, hydrogenated derivatives of aromatic petrocarbonate resins, cyclic aliphatic petroleum hydrocarbon resins, and hydrides of cyclic aliphatic petroleum hydrocarbon resins. These tackifier resins can be used alone or in combination. As the tackifier resin, a liquid type tackifier resin can also be used as long as the color tone is colorless to pale yellow, there is substantially no odor, and the thermal stability is good. Considering these characteristics comprehensively, a hydrogenated derivative such as the above-mentioned resin is preferable as the tackifier resin.

(C) A commercially available product can be used as the tackifier resin. As such commercial products, for example, ECR231C (trade name) manufactured by Exxon Mobile, ECR179EX (trade name), ECR5600 (trade name), Maruka Clearer H (trade name) manufactured by Maruzen Petrochemical Co., Ltd., and Clearlon manufactured by Yasuhara Chemical Co., Ltd. K100 (trade name), Clearon K4090 (trade name), Clearon K4100 (trade name) and Clearlon P105 (trade name), Arakawa Chemical Co., Ltd. Archon M100 (trade name), Archon P90 (trade name), Idemitsu Petrochemical Co., Ltd. Examples thereof include Imarb S100 (trade name), Imarb Y135 (trade name), Imarb P125 (trade name) and Imarb P100 (trade name), and Rigalite R7100 (trade name) manufactured by Eastman Chemical Co., Ltd. These commercially available tackifier resins can be used alone or in combination.

The hot melt adhesive of the present invention contains components (A) to (C) 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 has excellent coatability and can further reduce stringing.

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

In the present invention, the hot melt adhesive preferably further contains a wax. In addition, in this specification, "wax" is an organic substance having a weight average molecular weight of less than 10,000, which becomes a solid at room temperature and becomes a liquid when heated, and is generally referred to as "wax", and has wax-like properties. The hot melt adhesive according to the present invention is not particularly limited as long as it can be obtained. The wax may be synthetic wax or natural wax.

Examples of the synthetic wax include Fisher Tropsch wax, polyolefin wax (for example, polyethylene wax, polypropylene wax, polyethylene / polypropylene wax) and the like.

"Fischer-Tropsch wax" refers to what is generally referred to as Fischer-Tropsch wax, which is synthesized by the Fischer-Tropsch method. Fischer-Tropsch wax is a wax obtained by separating a wax from a wax in which the component molecules have a relatively wide carbon number distribution so that the component molecules have a narrow carbon number distribution.

As Fischer-Tropsch wax, Sazole H1 (trade name), Sazole C80 (trade name) of Sazole Wax Co., Ltd., and FT-115 (trade name) of Nippon Seiro Co., Ltd. are commercially available.

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

Paraffin wax is a wax that is solid at room temperature and is separated and produced from vacuum distillation extract oil. A typical paraffin wax is the Paraffin Wax series manufactured by Nippon Seiro Co., Ltd.

Microcrystalline wax is a wax that is solid at room temperature and is separated and produced from a vacuum distillation bottom or heavy extract oil. A typical microcrystalline wax is the Hi-Mic series manufactured by Nippon Seiro Co., Ltd.

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

The hot melt adhesive of the present invention preferably contains a natural wax, "paraffin wax". When the paraffin wax is blended, the hot melt adhesive of the present invention has an improved cohesive force and becomes hard, so that it is possible to prevent the corrugated board base material from being damaged when unloading the corrugated cardboard.

The hot melt adhesive of the present invention preferably contains a plasticizer. The "plasticizer" is blended for the purpose of lowering the melt viscosity of the hot melt adhesive, imparting flexibility, and improving the wetting of the adherend, and is compatible with the ethylene-based copolymer, and is the hot object of the present invention. The melt adhesive is not particularly limited as long as it can be obtained. Examples of the plasticizer include paraffin-based oils, naphthenic oils, and aromatic oils. Colorless and odorless paraffinic oils are particularly preferred.

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

As the plasticizer, a commercially available product can be used. For example, White Oil Bloom350 (trade name) manufactured by Kukdong Oil & Chem, Diana Fresia S32 (trade name) manufactured by Idemitsu Kosan Co., Ltd., Diana Process Oil PW-90 (trade name), DN Oil KP-68 (trade name), BP. Examples thereof include Oiler 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, if necessary. Examples of such various additives include stabilizers (ultraviolet absorbers, antioxidants) and fine particle fillers.

The "stabilizer" is compounded to prevent the decrease in molecular weight, gelation, coloring, generation of odor, etc. of the hot melt adhesive due to heat, air, light, etc., and to improve the stability of the hot melt adhesive. It is not particularly limited as long as it can obtain the hot melt adhesive intended by the present invention. Examples of the stabilizer include antioxidants and ultraviolet absorbers.

"Ultraviolet absorbers" are used to improve the light resistance of hot melt adhesives. "Antioxidants" are used to prevent oxidative deterioration of hot melt adhesives. The antioxidant and the ultraviolet absorber are generally used for hot melt adhesives, and are not particularly limited as long as they can obtain the paper products of interest described later.

Examples of the "antioxidant" include phenol-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Examples of the ultraviolet absorber include a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber. Further, a lactone-based stabilizer can be added. These can be used alone or in combination.

Commercially available products can be used as the stabilizer. For example, Sumitomo Chemical Industry Co., Ltd.'s Sumilyzer GM (trade name), Sumilyzer TPD (trade name) and Sumilyzer TPS (trade name), BASF Japan's Irganox 1010 (trade name), Irganox HP2225FF (trade name). ), Irgafoss 168 (trade name) and Irganox 1520 (trade name), ADEKA's Adecastab AO-60 (trade name), JF77 (trade name) manufactured by Johoku Kagaku Co., Ltd., JP-650 (trade name). Can be done. 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 may be any generally used one, and is not particularly limited as long as the hot melt adhesive intended by the present invention can be obtained. Examples of the "fine particle filler" include mica, calcium carbonate, kaolin, talc, titanium oxide, diatomaceous earth, urea-based resin, styrene beads, calcined clay, starch and the like. These shapes are preferably spherical, and their dimensions (diameter in the case of spherical shape) are not particularly limited.

The hot melt adhesive according to the present invention uses a generally known method for producing a hot melt adhesive to (A) amorphous poly α-olefin, (B) crystalline poly α-olefin, ( C) It is manufactured by blending a tackifier resin, a plasticizer or wax as needed, and the above-mentioned various additives.

For example, it can be produced by blending a predetermined amount of the above-mentioned components and heating and melting. As long as the desired hot melt adhesive can be obtained, the order in which each component is added, 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 corrugated cardboard, cooled and solidified to form a coating film of the hot melt adhesive on the surface of the corrugated cardboard.

The method of applying the hot melt adhesive is not particularly limited as long as the object of the present invention can be achieved, but a hot melt applicator is widely used. Examples of the hot melt applicator include Problue P4 Melter (trade name) and Problue P10 Melter (trade name) manufactured by Nordson.

The method of coating is roughly classified into, for example, contact coating and non-contact coating. "Contact coating" refers to a coating method in which a ejector is brought into contact with a member or a film when applying a hot melt adhesive, and "non-contact coating" refers to a coating method when applying a hot melt adhesive. A coating method that does not come into contact with members or films. Examples of the contact coating method 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 shape, omega coating and control seam coating that can be applied in a wavy shape, and surface coating. Examples thereof include slot spray coating, curtain spray coating, dot coating that can be applied in dots, and bead coating that can be applied linearly.

When applying the hot-melt adhesive of the present invention with a hot-melt applicator (even when the hot-melt adhesive is ejected horizontally to the ground and applied), the hot-melt adhesive is towed. Almost disappears. Therefore, the adherend and the applicator are not contaminated with the thread-like material.

The amount of the hot melt adhesive applied is not particularly limited, but is, for example, 1 to 5 g / m. Further, the application pattern of the hot melt adhesive may be appropriately determined, and is, for example, a bead shape.

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

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

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

INDUSTRIAL APPLICABILITY The present invention is particularly useful as a "hot melt adhesive for corrugated cardboard" that prevents the stacked corrugated cardboard boxes from collapsing, does not damage the corrugated cardboard base material, and is also excellent in coatability and reduction of stringing. Is.

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

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but these Examples are merely one aspect of the present invention, and the present invention is not limited to these examples. However, Examples 7, 8 , 10 and 11 are reference examples. The proportions shown in the examples are based on the weight of the non-volatile content unless otherwise specified. The components for producing a hot melt adhesive are shown below.

(A) Acrystalline poly-α-olefin (A1) Acrystalline propylene / ethylene / 1-butene copolymer (Bestplast 703 (trade name), manufactured by Ebonic, 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 Ebonic, 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 Ebonic, viscosity 50,000 mPa · s: 190 ° C., softening point 107 ° C., density 0.87 g / cm ³ )
(A4) Amorphous ethylene / propylene copolymer (Lexentac 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 (Eastflex P1010PL (trade name), manufactured by Eastman Chemical Company, viscosity 1000 mPa · s: 190 ° C., softening point 155 ° C., density 0.87 g / cm ³ )

(B) Crystalline poly α-olefin (B1) polypropylene homopolymer obtained by polymerization with a metallocene catalyst (Elmodu 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 a 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 a metallocene catalyst (B3) Polypropylene homopolymer (Ricosen PP6102 (trade name), manufactured by Clariant, viscosity 60 mPa · s: 170 ° C., density 0.90 g / cm ³ ) Polymer obtained by polymerizing with a metallocene catalyst. (B4) Propylene / ethylene copolymer (Vistamax 6202 (trade name), manufactured by Exxon Mobile, MFR 20 g / 10 min: 230 ° C., density 0.86 g / cm ³ ) Polymer obtained by polymerization with a metallocene catalyst (B5) ) Ethylene / octene copolymer (affinity GA1900 (trade name), manufactured by Dow Chemical Co., Ltd., MFR 1000 g / 10 min: 190 ° C., density 0.87 g / cm ³ ) Polymer obtained by polymerization with a metallocene catalyst (B'6) Polyethylene homopolymer (Petrosen 353 (trade name), manufactured by Toso Co., Ltd., MFR 145 g / 10 min: 190 ° C., density 0.92 g / cm ³ ) Polymer obtained by polymerizing with a Chigra Natta catalyst (B'7) Polyethylene / Polybutene Polymer (DP8911ME (trade name), manufactured by Basel, MFR 200 g / 10 min: 190 ° C., density 0.90 g / cm ³ ) Polymer obtained by polymerizing with a Chigra natta catalyst.

(C) Adhesive-imparting resin
(C1) Hydrogenated dicyclopentadiene resin (Aimab P100 (trade name), manufactured by Idemitsu Kosan Co., Ltd., softening point 100 ° C.)
(C2) Hydrogenated cyclic aliphatic petroleum hydrocarbon resin (Alcon P90 (trade name), manufactured by Arakawa Chemical Industry Co., Ltd., softening point 90 ° C.)
(C3) Hydrogenated terpene resin (Clearlon 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 Nippon Sun Oil Co., Ltd.)

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

(F) Stabilizer
(F1) Antioxidant (ADEKA STAB AO-60 (trade name), manufactured by ADEKA CORPORATION)

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

○ Physical characteristics / performance evaluation <Viscosity measurement>
The viscosity of each hot melt adhesive was evaluated at 160 ° C. and 180 ° C. based on the JAI7-1991 B method. A Brookfield viscometer, No. 27 rotor, was used for the measurement.

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

This sample was attached to a 200 g weight with a bottom size of 40 cm and ² squares from the PET film side to form a "slip piece", and the "slip piece" was placed on a K-liner cardboard and pulled at a speed of 100 mm / min. ..

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

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

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

⊚: Tilt angle is 45 degrees or more ○: Tilt angle is 40 degrees or more and less than 45 degrees Δ: Tilt angle is 35 degrees or more and less than 40 degrees ×: Tilt angle is less than 35 degrees

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

After the hot melt adhesive was completely solidified, another corrugated cardboard was superposed, a 3 kg weight was placed on the corrugated cardboard, and the mixture was placed under a load in an atmosphere of 40 ° C. for 24 hours. After that, the stacked corrugated cardboard was peeled off by hand, and the condition of the corrugated cardboard was confirmed to evaluate the damage property of the base material. The evaluation criteria for the damage to the step base material are shown below.

⊚: No damage.
○: There is some fluffing.
Δ: Only one of the four points was peeled off.
X: Of the 4 points, 2 or more points were peeled off.

○ Workability evaluation <thread pulling performance evaluation>
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 the falling object between the hot melt gun and the adherend was visually observed, and the stringability was evaluated. The measurement conditions are as follows.

Temperature setting: The temperature inside the tank, the temperature inside the hose, and the temperature inside the nozzle are all 180 ° C.
Nozzle diameter: 16/1000 inches Nozzle: office (number of discharge ports: 1)
Coating pressure: 0.3MPa
Number of spray shots: 90 shots / 30 seconds

◯: No thread is pulled between the nozzle and the adherend.
Δ: The thread may be pulled between the nozzle and the adherend.
X: In most cases, the thread is pulled from the nozzle to the adherend, or after ejection, the thread is pulled from the sagging of the nozzle.

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

◯: The entire coated portion is uniform.
Δ: Only the end portion of the coated portion is non-uniform.
X: The entire coated portion is non-uniform.

[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, and can prevent the stacked corrugated cardboard boxes from collapsing and prevent damage to the corrugated cardboard substrate.

Claims (6)

It contains (A) an amorphous poly α-olefin, (B) a crystalline poly α-olefin obtained by polymerizing an α-olefin with a metallocene catalyst, and (C) a tackifier resin.
(B) is contained in an amount of 5 to 50 parts by weight, and (C) is contained in an amount of 7 to 20 parts by weight, based on 100 parts by weight of the total weights of (A) to (C).
A hot melt adhesive having a melt viscosity at 180 ° C. of 3,000 mPa · s or less .
(B) A hot melt adhesive in which the crystalline poly-α-olefin contains a polypropylene homopolymer . (A) The hot melt adhesive according to claim 1, wherein the amorphous poly α-olefin has a chemical structure derived from propylene. (A) The hot melt adhesive according to claim 1 or 2, wherein the amorphous poly α-olefin contains a propylene / ethylene / 1-butene copolymer. (A) The hot melt adhesive according to claim 3, wherein the amorphous poly α-olefin further contains a polypropylene homopolymer. The hot melt adhesive according to any one of claims 1 to 4 , which is applied to corrugated cardboard. A corrugated cardboard on which a coating film of the hot melt adhesive according to any one of claims 1 to 5 is formed.