JP7336188B2 - hot melt adhesive - Google Patents

Description

The present invention relates to a hot melt adhesive and corrugated board coated with the hot melt adhesive.

Hot-melt adhesives are solvent-free adhesives that are applied to the adherend by heating and melting, and then solidify by cooling to develop adhesiveness, so instant and high-speed adhesion is possible. It is used in a wide range of fields such as paper processing, woodworking, sanitary materials and electronic fields.

As the base polymer of the hot-melt adhesive, depending on the application, for example, ethylene-vinyl acetate copolymer (hereinafter also referred to as "EVA"), ethylene-ethyl acrylate copolymer (hereinafter also referred to as "EEA") ) and other ethylene / carboxylic acid ester copolymers,
Polyolefins such as polyethylene, polypropylene, copolymers of ethylene and α-olefins;
Synthetic rubbers such as styrenic block copolymers (e.g., styrene-isoprene-styrene block copolymers, styrene-butadiene-styrene block copolymers and hydrogenated products thereof);
Polyurethane; etc. are widely used.

Among these hot-melt adhesives, hot-melt adhesives using amorphous poly-α-olefin (APAO) as a base polymer are often used for cardboard processing, as disclosed in Patent Documents 1 and 2. be.

Corrugated board is a sheet of corrugated paperboard with a paperboard liner on one or both sides. Paperboards used for liners include kraft liner (K liner) made from kraft pulp and waste paper and jute liner (C liner) made from waste paper. A typical example of corrugated board includes outer corrugated board described in JIS 1516.

The hot-melt adhesive for corrugated board can be used not only for processing corrugated board but also as a non-slip member for corrugated board. The surfaces of corrugated board are smooth and easy to slide against each other. A plurality of stacked corrugated cardboard boxes, for example, can collapse when moved by even a slight tilt, which increases the risk of handling the cargo and lowers work efficiency.

When stacking multiple cardboard boxes, if a hot-melt adhesive coating is formed on the cardboard surface, the hot-melt adhesive coating prevents the cardboard surfaces from slipping and the cargo collapses even if it tilts. Gone. The hot-melt adhesive coating film is formed, for example, by heating and melting the hot-melt adhesive, applying it to the surface of the corrugated board, and cooling and solidifying the coating layer.

Multiple cardboard boxes are stacked on an olefin pallet to prevent the cargo from collapsing. As a result, safety is improved when handling the cargo, and it becomes easier to move the cargo on the pallet. It also improves efficiency.

When corrugated cardboard boxes are stacked on top of the hot-melt adhesive coating film as described above, if the hot-melt adhesive that has cooled and solidified still has excellent adhesion, the stacked cardboard boxes will stick together strongly. substrate damage may occur when unpacking the cardboard.

Therefore, hot melt adhesives for corrugated board are desired to have at least two properties of preventing slippage between stacked corrugated boards and not adhering to corrugated boards in a cooled and solidified state.

Patent Document 1 discloses a hot-melt adhesive containing an amorphous poly-α-olefin, a crystalline metallocene-based poly-α-olefin, and a tackifying resin ([Claim 1], [Table 1] to [Table 8 ]). The hot-melt adhesive of Patent Literature 1 has a coating film that is cooled and solidified and has excellent friction against corrugated cardboard and has excellent anti-slip performance. However, corrugated cardboard loads having this hot melt adhesive coating can be difficult to remove from the pallet, and there is still room for improvement in terms of release performance.

Patent Document 2 discloses an ethylene-α-olefin copolymer, a polypropylene having a softening point of 80 to 100°C, a tackifier having a softening point of 110 to 150°C, and a hot melt adhesive containing wax and paper A packaging material is disclosed ([Claim 1], [Claim 6], [Table 1]). The hot melt adhesive of Patent Document 2 uses an ethylene-1-octene copolymer as the ethylene-α-olefin copolymer, so that it can be used in a wide temperature environment of -20 to 55 ° C. It also maintains excellent adhesion performance. However, Patent Document 2 does not describe the anti-slip performance or peeling performance of the solidified coating film on corrugated cardboard.

Furthermore, depending on the composition of the hot melt adhesive of Patent Document 2, when it is discharged from a hot melt gun and applied to an adherend, stringiness or seepage to a paper substrate such as corrugated cardboard occurs.

JP 2016-159916 A JP 2014-208812 A

The present invention is intended to solve the above-mentioned conventional problems, and the object of the present invention is to make the solidified coating film excellent in anti-slip performance against corrugated cardboard, and at the same time, to easily peel corrugated cardboard from pallets without damaging the corrugated board base material. To provide a hot-melt adhesive capable of

The present invention comprises (A) a crystalline olefin polymer, (B) an amorphous olefin polymer, (C) a tackifying resin and (D) a wax,
(A) The crystalline olefin polymer provides a hot melt adhesive comprising (A1) a metallocene propylene/ethylene copolymer having an ethylene content of 5 to 10% by weight.

In one embodiment, the metallocene-based propylene/ethylene copolymer (A1) has a density of 0.87 to 0.95 g/cm ³ and a melt viscosity of 1000 to 2000 mPas at 190°C.

In one embodiment, (B) the amorphous olefin polymer contains (B1) a propylene/ethylene/butene copolymer.

In one embodiment, (A1) is contained in an amount of 10 to 70 parts by weight per 100 parts by weight of the total weight of (A) to (D).

In one embodiment, (B1) is contained in an amount of 2 to 20 parts by weight per 100 parts by weight of the total weight of (A) to (D).

In addition, the present invention provides corrugated board having a coating film of any of the hot melt adhesives adhered and solidified on the coated portion.

According to the present invention, a hot-melt adhesive is provided in which the solidified coating film is excellent in anti-slip performance against corrugated board, and at the same time, the corrugated board can be easily peeled off from the pallet without damaging the corrugated board base material. Corrugated cardboard having a coating film of the hot-melt adhesive of the present invention, even when stacked on a pallet, is less slippery and does not damage the base material when handled by workers. Furthermore, when the cardboard is unloaded from the pallet, the cardboard can be easily separated from the pallet, which improves the efficiency of the unpacking work.

Corrugated board is a sheet of corrugated paperboard with a paperboard liner on one or both sides of the corrugated medium. Paperboards used for liners include kraft liner (K liner) made from kraft pulp and waste paper and jute liner (C liner) made from waste paper. A typical example of corrugated board includes outer corrugated board described in JIS 1516.

The hot melt adhesive according to the present invention contains (A) a crystalline olefin polymer, (B) an amorphous olefin polymer, (C) a tackifier resin and (D) wax as essential components.

As used herein, the term "hot-melt adhesive" refers to an adhesive that is solid at room temperature, but has fluidity when heated and melted, and can be applied to objects such as substrates and adherends. An adhesive that hardens and adheres when cooled.

Here, "crystallinity" means what is usually called "crystallinity", and more specifically refers to a state in which macromolecules are regularly arranged. "Amorphous" usually means not crystalline, but more specifically, it is a state in which the molecular chains of the polymer are arranged irregularly.

<(A) Crystalline Olefin Polymer>
(A) Crystalline olefin polymer such as polyethylene, polypropylene, ethylene/propylene copolymer, ethylene/α-olefin copolymer, propylene/α-olefin copolymer, ethylene/propylene/α-olefin copolymer Copolymers, ethylene/1-butene copolymers and propylene/1-butene copolymers can be exemplified. These copolymers may be used alone or in combination.

(A) As an example of a commercially available crystalline olefin polymer,
Dow Chemical Company Affinity GA1900 (trade name), Affinity GA1950 (trade name), Affinity EG8185 (trade name), Affinity EG8200 (trade name), Engage 8137 (trade name), Engage 8180 (trade name), Engage 8400 (Product name);
Vistamax 2330 (trade name), Vistamax 6202 (trade name), Vistamax 8880 (trade name) manufactured by ExxonMobil;
Evolue SP1071C (trade name), Evolue SP2030 (trade name), and Evolue SP2530S (trade name) manufactured by Prime Polymer;
Elmodu S400 (trade name), Elmodu S600 (trade name), Elmodu S901 (trade name) manufactured by Idemitsu Kosan;
etc.

(A) The crystalline olefin polymer contains (A1) a metallocene-based propylene/ethylene copolymer. (A1) The metallocene-based propylene/ethylene copolymer is a polymer produced by polymerizing ethylene and propylene using a metallocene catalyst. A polymer produced with a metallocene catalyst has a very narrow molecular weight distribution and does not cause a bias in crystallinity. Since the metallocene-based propylene/ethylene copolymer is uniform in terms of the arrangement of ethylene and propylene sites, the content of each structural unit, and the like, low-molecular-weight products are less likely to occur. As a result, the hot-melt adhesive of the present invention is considered to have low adhesion of the solidified coating film, excellent releasability, and excellent heat resistance.

By containing the component (A1), the hot melt adhesive of the present invention has improved anti-slip performance at high temperatures (about 50 ° C.), is less likely to damage the corrugated board substrate when peeled, and can be removed from the olefin substrate (pallet). to improve the peelability of cardboard.

(A1) The ethylene content of the metallocene-based propylene/ethylene copolymer is 5 to 10% by weight, preferably 6 to 9% by weight, most preferably 7 to 8% by weight. When the ethylene content of component (A1) is within the above range, the hot melt adhesive of the present invention maintains a good balance between heat resistance and anti-slip performance, and is useful for anti-slip applications on cardboard surfaces.

In this specification, the ethylene content is the ratio of the ethylene structure to the total weight of ethylene and the α-olefin polymer, and is a value measured by the Exxon Mobil method based on the ASTM method.

(A1) The density of the metallocene-based propylene/ethylene copolymer is preferably 0.87 to 0.95 g/cm ² . When the density of (A1) is within the above range, the hot-melt adhesive of the present invention can maintain an appropriate degree of hardness, and when applied to corrugated board, the corrugated board substrate is less likely to be damaged, and the adhesive is slip-resistant. Performance will be better.

As used herein, density is weight per unit volume and is a value measured according to ASTM D1505-03.

(A1) The 190° C. viscosity of the metallocene-based propylene/ethylene copolymer is preferably 1000 to 2000 mPas, more preferably 1100 to 1900 mPas.

When the viscosity of (A1) is within the above range, the hot melt adhesive of the present invention can maintain an appropriate shape (spread and height) when applied to the surface of corrugated cardboard, and has better anti-slip performance. improves. The 190° C. viscosity of (A1) is a value measured according to JAI7-1991 B method. A Brookfield viscometer, No. 27 rotor was used as a measuring device.

(A1) An example of a commercial product of the metallocene-based propylene/ethylene copolymer is Vistamax 8880 manufactured by ExxonMobil, and Vistamax A (prototype), which will be described later, also corresponds to (A1).

<(B) Amorphous Olefin Polymer>
In the present invention, “(B) amorphous olefin polymer (hereinafter also referred to as “component (B)”)” means an amorphous α-olefin polymer, generally amorphous It is called a poly-α-olefin. (B) the amorphous olefin polymer is not particularly limited as long as the hot-melt adhesive according to the present invention can be obtained.

Here, "amorphous" usually means not crystalline, and more specifically, it refers to a state in which polymer molecular chains are arranged irregularly. (B) By blending the amorphous olefin polymer into the hot melt adhesive, the hot melt adhesive has a high coefficient of friction and becomes less slippery on the surface of the adherend (corrugated cardboard).

Friction is a force acting in a direction that hinders the movement of an object on the surface of another object when it tries to move or is in motion while touching the surface of another object. Friction is static friction that tries to stop one object from sliding due to the state of relative motion of two objects ("maximum static friction force", which is the frictional force when an object is about to start sliding). , and kinetic friction (sliding friction, rolling friction, etc.) that tries to stop a moving object.

As used herein, friction means static friction and coefficient of friction means static coefficient of friction.

(B) Amorphous olefin polymers such as amorphous polypropylene, amorphous polyethylene, copolymers of amorphous propylene and other α-olefins, and amorphous ethylene and Copolymers with other α-olefins can be exemplified. These polymers may be used singly or in combination.

(B) Specific examples of the amorphous olefin polymer include polypropylene (homopolymer), propylene/ethylene copolymer, propylene/1-butene copolymer, and terpolymer of propylene/ethylene/1-butene. Examples include coalescence, terpolymer of propylene/1-hexene/1-octene, terpolymer of propylene/1-hexene/methylpentene, 1-polybutene (homopolymer), and the like.

In the present invention, (B) the amorphous olefin polymer preferably has a chemical structure derived from propylene. A 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 increases and it becomes difficult to slip. can also be prevented.

(B) Commercially available amorphous olefin polymers include:
Bestplast 703 (trade name), Bestplast 704 (trade name), and Bestplast 708 (trade name) manufactured by Evonik Degussa;
Eastoflex (trade name) E1016PL-1 and Eastoflex PP1010PL (trade name) manufactured by Eastman Chemical;
Lexentac 2304 (trade name) manufactured by Huntsman;
etc.

In the present invention, the density of the (B) amorphous olefin polymer is preferably 1.00 g/cm ³ or less, particularly preferably 0.80 g/cm ³ to 0.90 g/cm ³ , and more preferably 0.85 g/cm ³ . ~0.88 g/cm ³ is most preferred. (B) When the density of the amorphous olefin polymer is within the above range, the hot melt adhesive of the present invention becomes less slippery, and collapse of the cardboard box can be more reliably prevented.

(B) the amorphous olefin polymer preferably contains (B1) a propylene/ethylene/1-butene copolymer. By blending the propylene/ethylene/1-butene copolymer, collapse of piled cardboard boxes can be reliably prevented, and at the same time damage to the cardboard substrate can be prevented.

(B1) Commercially available propylene/ethylene/1-butene copolymers include Bestplast 703 (trade name), Bestplast 704 (trade name), and Bestplast 708 (trade name) manufactured by Evonik Degussa. Plast series.

<(C) Tackifying resin>
"(C) Tackifying resin" is commonly used in hot-melt adhesives, and is not particularly limited as long as the desired hot-melt adhesive of the present invention can be obtained. do not have.

Examples of tackifying resins include natural rosin, modified rosin, hydrogenated 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 hydrogenated rosin. , copolymers of natural terpenes, three-dimensional polymers of natural terpenes, hydrogenated derivatives of copolymers of hydrogenated terpenes, polyterpene resins, hydrogenated derivatives of phenolic modified terpene resins, aliphatic petroleum hydrocarbon resins, aliphatic petroleum hydrocarbon resins 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. As the tackifying resin, a liquid type tackifying resin can also be used as long as it is colorless to pale yellow in color tone, has substantially no odor, and has good thermal stability. Considering these characteristics comprehensively, hydrogenated derivatives such as the above resins are preferable as the tackifying resin.

(C) A commercial item can be used as tackifying resin. Examples of such commercial products include ECR231C (trade name), ECR179EX (trade name), and ECR5600 (trade name) manufactured by ExxonMobil, Maruka Clear H (trade name) manufactured by Maruzen Petrochemical Co., Ltd., and Clearon manufactured by Yasuhara Chemical Co., Ltd. K100 (trade name), Clearon K4090 (trade name), Clearon K4100 (trade name) and Clearon P105 (trade name), Alcon M100 (trade name) manufactured by Arakawa Chemical Co., Ltd., Alcon P90 (trade name), Idemitsu Petrochemical Co., Ltd. Imarv S100 (trade name), Imarv Y135 (trade name), Imarv P125 (trade name) and Imarv P100 (trade name) manufactured by JTXG Energy Co., Ltd. T-REZ HC103 (trade name), T-REZ HA103 (trade name) name), T-REZ HA125 (trade name), T-REZ HB103 (trade name), T-REZ HA085 (trade name), and Ligalite R7100 (trade name) manufactured by Eastman Chemical Company. These commercially available tackifying resins can be used alone or in combination.

<(D) Wax>
In the present invention, the hot melt adhesive contains (D) wax. As used herein, the term “wax” refers to an organic substance having a weight-average molecular weight of less than 15,000, which is solid at room temperature and liquid when heated, generally referred to as “wax”, and has wax-like properties. is not particularly limited as long as the hot melt adhesive according to the present invention can be obtained. The wax can be synthetic wax or natural wax.

Examples of synthetic wax include Fischer-Tropsch wax, polyolefin wax (eg, polyethylene wax, polypropylene wax, polyethylene/polypropylene wax), and the like.

"Fischer-Tropsch wax" means a wax synthesized by the Fischer-Tropsch method and generally referred to as Fischer-Tropsch wax. Fischer-Tropsch wax is obtained by fractionating a wax from a wax whose component molecules have a relatively wide carbon number distribution so that the component molecules have a narrow carbon number distribution.

Sasol H1 (trade name) and Sasol C80 (trade name) available from Sasol Wax Co., Ltd. and FT-115 (trade name) available from Nippon Seiro Co., Ltd. are commercially available as Fischer-Tropsch waxes.

Natural waxes include paraffin wax, microcrystalline wax and petrolatum.

Paraffin wax is a wax that is solid at room temperature and is separated from oil extracted by distillation under reduced pressure. As a typical paraffin wax, the Paraffin Wax series manufactured by Nippon Seiro Co., Ltd. can be mentioned.

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

The petrolatum is a semi-solid wax at room temperature separated from the vacuum distillation bottom. As a typical petrolatum, Centon CP series manufactured by Chuo Yuka Co., Ltd. can be mentioned.

These waxes may be used alone or in combination.

The hot melt adhesives of the present invention preferably contain "paraffin wax" which is a natural wax. When the paraffin wax is blended, the hot melt adhesive of the present invention has improved cohesive strength and becomes hard, so that damage to the corrugated board substrate can be prevented when unloading the corrugated board.

<Hot melt adhesive>
The hot-melt adhesive of the present invention contains 10 to 70 parts by weight of (A1) the metallocene-based propylene/ethylene copolymer with respect to 100 parts by weight of the total weight of components (A) to (D). 30 to 70 parts by weight is particularly preferred, and 40 to 65 parts by weight is most preferred.

(A1) When the content of the metallocene-based propylene/ethylene copolymer is within the above range, when the hot-melt adhesive of the present invention is applied to corrugated board, the corrugated board substrate is less likely to be damaged and the corrugated board is peeled off from the pallet. becomes easier.

In the hot melt adhesive of the present invention, the blending amount of the propylene/ethylene/butene copolymer (B1) is preferably 2 to 20 parts by weight with respect to 100 parts by weight of the total weight of the components (A) to (D). 5 to 20 parts by weight is preferred, and 5 to 15 parts by weight is most preferred.

(B1) When the content of the propylene/ethylene/butene copolymer is within the above range, the hot-melt adhesive of the present invention, when applied to corrugated board, exhibits excellent non-slip performance on the corrugated board surface. .

In the hot melt adhesive of the present invention, the amount of the tackifying resin (C) is preferably 10 to 40 parts by weight, particularly 15 to 40 parts by weight, per 100 parts by weight of the total weight of components (A) to (D). is preferred, and 20 to 30 parts by weight is most preferred.

(C) When the amount of the tackifying resin is within the above range, the hot melt adhesive has improved initial adhesiveness, improved anti-slip performance, less damage to the cardboard substrate, and easy peeling of the cardboard from the pallet. can do.

In the hot melt adhesive of the present invention, the amount of wax (D) is preferably 5 to 20 parts by weight, particularly preferably 5 to 15 parts by weight, per 100 parts by weight of components (A) to (D). , 5 to 10 parts by weight is most desirable.

(D) When the blending amount of the wax is within the above range, the hot-melt adhesive has a low viscosity and improves the compatibility of each component, and also improves the cohesive force, so that the hot-melt adhesive has excellent anti-slip performance. , it is possible to prevent damage to the cardboard base material.

The hot melt adhesive of the present invention preferably contains a plasticizer. "Plasticizer" is blended for the purpose of reducing the melt viscosity of the hot melt adhesive, imparting flexibility, and improving wettability to the adherend, and is compatible with the ethylene copolymer, and the hot There are no particular limitations as long as a melt adhesive can be obtained. Plasticizers include, for example, paraffinic oils, naphthenic oils and aromatic oils. Paraffinic oils, which are colorless and odorless, are particularly preferred.

When the oil is blended, the compatibility of the components (A) to (C) is improved, so that the hot melt adhesive of the present invention is imparted with flexibility, slipperiness on the surface of corrugated board and damage to the corrugated board base material. can be prevented, stringing can be reduced, and coatability is improved.

A commercial item can be used as a plasticizer. For example, Kukdong Oil & Chem Co., Ltd. White Oil Broom 350 (trade name), Idemitsu Kosan Dianafrecia S32 (trade name), Diana Process Oil PW-90 (trade name), DN Oil KP-68 (trade name), BP Enerper M1930 (trade name) manufactured by Chemicals, Kaydol (trade name) manufactured by Crompton, Primol 352 (trade name) manufactured by Esso, and Sunpure N90 (trade name) manufactured by Japan Sun Oil Co., Ltd. can be exemplified. These plasticizers can be used alone or in combination.

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

"Stabilizer" is added to improve the stability of hot melt adhesives by preventing molecular weight reduction, gelation, coloration, and odor generation due to heat, air, light, etc. There is no particular limitation as long as the hot-melt adhesive targeted by the present invention can be obtained. Examples of stabilizers include antioxidants and UV absorbers.

"UV absorbers" are used to improve the lightfastness of hot melt adhesives. "Antioxidants" are used to prevent oxidative degradation of hot melt adhesives. Antioxidants and UV absorbers are generally used in hot-melt adhesives, and are not particularly limited as long as the intended paper products described below can be obtained.

Examples of "antioxidants" include phenol antioxidants, sulfur antioxidants, and phosphorus antioxidants. Examples of UV absorbers include benzotriazole UV absorbers and benzophenone UV 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, Sumitomo Chemical Co., Ltd. Sumilizer GM (trade name), Sumilizer TPD (trade name) and Sumilizer TPS (trade name), BASF Japan Ltd. Irganox 1010 (trade name), Irganox HP2225FF (trade name) ), Irgafos 168 (trade name) and Irganox 1520 (trade name), ADEKA's Adekastab AO-60 (trade name), Johoku Kagaku JF77 (trade name), and JP-650 (trade name). can be done. These stabilizers can be used alone or in combination.

The hot melt adhesives of the present invention can further contain particulate fillers. The fine particle filler is not particularly limited as long as it is generally used and can obtain the hot-melt adhesive aimed at by the present invention. Examples of the "fine particle filler" include mica, calcium carbonate, kaolin, talc, titanium oxide, diatomaceous earth, urea-based resin, styrene beads, calcined clay, and starch. These shapes are preferably spherical, and there are no particular restrictions on their dimensions (diameter if spherical).

The hot-melt adhesive according to the present invention is prepared by using a generally known hot-melt adhesive manufacturing method to prepare (A) a crystalline olefin polymer, (B) an amorphous olefin polymer, (C) It is produced by blending a tackifying resin, (D) wax, and optionally a plasticizer and the various additives described above.

For example, it can be produced by mixing predetermined amounts of the above components and heating and melting them. As long as the desired hot-melt adhesive can be obtained, the order of adding each component, the heating method, etc. are not particularly limited.

<Cardboard coated with hot melt adhesive>
The hot-melt adhesive according to the present invention is heated and melted, applied to the coated portion of the corrugated board, cooled and solidified to form a hot-melt adhesive coating on the surface of the corrugated board.

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 hot-melt applicators are widely used. Examples of the hot-melt applicator include Problue P4 Melter (trade name) and Problue P10 Melter (trade name) manufactured by Nordson.

The coating method is roughly classified into, for example, contact coating and non-contact coating. "Contact application" refers to the application method in which the ejector is brought into contact with the member or film when applying the hot melt adhesive. It refers to a coating method that does not contact the member or film. Examples of contact coating methods include slot coater coating and roll coater coating. Examples of non-contact coating methods include spiral coating capable of spiral coating, omega coating and control seam coating capable of wave-like coating, and planar coating. Examples include slot spray coating and curtain spray coating that can be applied, dot coating that can be applied in points, and bead coating that can be applied in a line.

When applying the hot-melt adhesive of the present invention with a hot-melt applicator (even when the hot-melt applicator dispenses the hot-melt adhesive in a horizontal direction to the ground), stringing of the hot-melt adhesive almost disappears. Therefore, the adherend and the applicator are not stained with filamentous substances.

The coating amount of the hot melt adhesive is not particularly limited, but is, for example, 1 to 5 g/m. Also, 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 board has a large frictional force against the corrugated board. As a result, even when the cardboard boxes stacked on the hot-melt adhesive coating are moved or tilted, collapse of the cargo can be prevented. The coating film of hot-melt adhesive preferably has a static friction coefficient of 14 or more, more preferably 16.5 or more, and still more preferably 18 or more against the surface of the corrugated board.

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

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

The hot melt adhesive of the present invention is a "hot melt adhesive for corrugated cardboard" that prevents collapse of stacked corrugated cardboard boxes, does not damage the corrugated board base material, and is excellent in coatability and reduction of stringing. It is particularly useful as a "agent".

The corrugated board according to the present invention is corrugated board obtained using the hot-melt adhesive described above. The corrugated board of the present invention is particularly preferably corrugated board having a surface coated with a hot-melt adhesive.

EXAMPLES Hereinafter, the present invention will be described specifically and 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 by these examples. Percentages given in the examples are by weight of non-volatiles unless otherwise specified. However, Examples 4 and 5 are reference examples.

Raw materials for hot-melt adhesives, formulations, and evaluation methods are described below.
(A) Crystalline olefin polymer (A1-1) Metallocene propylene/ethylene copolymer (ethylene content: 7.1% by weight, melting point: 112°C, 190°C melt viscosity: 1850 mPas, density: 0.88 g/cm ³ , Exxon Mobil Vistamax A ((prototype))
(A1-2) Metallocene propylene/ethylene copolymer (ethylene content: 6.0% by weight, melting point: 97°C, 190°C melt viscosity: 1200 mPas, density: 0.88 g/cm ³ , Vistamax 8880 manufactured by ExxonMobil (product given name))
(A2) Metallocene-based propylene homopolymer (melt flow rate: 350 g/10 min: 230°C, density 0.87 g/cm ³ , manufactured by Idemitsu Kosan Co., Ltd., Elmodu S600 (trade name))
(A3) Metallocene-based ethylene/octene copolymer (1-octene content: 30 to 40% by weight, melting point: 68°C, melt flow rate: 1000g/10min, Dow Chemical Company Affinity GA1900 (trade name))
(A4) Low-density polyethylene (melt flow rate: 145 g/10 min, Tosoh Petrothene 353 (trade name))
(A5) Metallocene-based ethylene/hexene copolymer (melting point: 95°C, Nipolon Z HM510R (trade name) manufactured by Tosoh Corporation)
(A6) Metallocene propylene/ethylene copolymer (ethylene content: 15.0% by weight, melt flow rate: 20 g/10 min, density: 0.86 g/cm ³ , Vistamax 6202 (trade name) manufactured by ExxonMobil)

(B) Amorphous olefin polymer (B1-1) Amorphous propylene/ethylene/butene copolymer (softening point: 124°C, 190°C melt viscosity: 2700 mPas, Bestplast 703 (trade name) manufactured by Evonik Degussa) )
(B1-2) Amorphous propylene/ethylene/butene copolymer (softening point: 105°C, 190°C melt viscosity: 3500 mPas, Bestplast 704 (trade name) manufactured by Evonik Degussa)
(B2) Amorphous propylene homopolymer (melt viscosity 1000 mPas at 190°C, softening point 155°C, density 0.87 g/cm ³ , Eastflex PP1010PL (trade name) manufactured by Eastman Chemical Co.)
(B3) Amorphous propylene/ethylene copolymer (190° C. melt viscosity 450 mPas, softening point 141° C., density 0.86 g/cm ³ , Huntsman Lexentac 2304 (trade name))

(C) Tackifier resin (C1) Hydrogenated alicyclic/aromatic copolymer hydrocarbon resin (softening point: 103 ° C., T-REZ HC103 (trade name) manufactured by JXTG Nippon Oil & Energy Corporation)
(C2) Hydrogenated alicyclic hydrocarbon resin (softening point: 103°C, T-REZ HA103 (trade name) manufactured by JXTG Nippon Oil & Energy Corporation)
(C3) Hydrogenated alicyclic hydrocarbon resin (softening point: 125°C, T-REZ HA125 (trade name) manufactured by JXTG Nippon Oil & Energy Corporation)

(D) Wax (D1) Fischer-Tropsch wax (melting point: 108°C, penetration of 2, Sasol Wax H1 (trade name) manufactured by Sasol)
(D2) Fischer-Tropsch wax (melting point: 80°C, penetration of 7, Sasol C80 (trade name) manufactured by Sasol)
(D3) Paraffin wax (Melting point: 69°C, Penetration 12, Paraffin 155F (trade name) manufactured by Nippon Seiro Co., Ltd.)
(D4) Microstalin wax (Melting point: 84°C, Penetration of 12, Hymic 1080 (trade name) manufactured by Nippon Seiro Co., Ltd.)
(D5) Polyethylene wax (Melting point: 109°C, Penetration 7, Hi-Wax 320P (trade name) manufactured by Mitsui Chemicals, Inc.)
(D6) polypropylene wax (melting point: 140/148°C, penetration of 1 or less, Mitsui Chemicals Hi-Wax NP105 (trade name))

(E) Plasticizer (E1) Paraffin oil (Dianafresia S32 (trade name) manufactured by Idemitsu Kosan Co., Ltd.)
(E2) Naphthenic oil (Sun Pure N90 (trade name) manufactured by Nippon Sun Oil Co., Ltd.)

(F) Antioxidant (F1) Phenolic antioxidant (ADEKA ADEKA STAB AO60 (trade name))
(F2) Phosphorus antioxidant (JP650 (trade name) manufactured by Johoku Kagaku Co., Ltd.)
(F3) Sulfur-based antioxidant (Sumilizer TPS (trade name) manufactured by Sumitomo Chemical Co., Ltd.)

These components were melt-mixed in proportions shown in Tables 1 and 3 using a universal stirrer at about 155° C. for about 1 hour to prepare hot-melt adhesives of Examples and Comparative Examples. For these hot melt adhesives, we evaluated the melt viscosity, the "maximum coefficient of static friction" against cardboard, tilt angle measurement (anti-slip performance), and damage to the cardboard substrate, and peeled off from the olefin substrate to confirm workability. They were evaluated for resistance, exudation, and stringiness. Evaluation results are shown in Tables 2 and 4.

<Inclination angle measurement: anti-slip performance>
A hot-melt adhesive melted at 180° C. was applied to a K-liner corrugated board in the form of a bead having a coating weight of 3 g/m and a length of 3 cm. After 60 seconds from the application, the corrugated board was cured in thermostats at 50°C, 23°C and 0°C. After an additional 30 seconds, another K-liner corrugated cardboard with a 3 kg weight was superimposed on the hot melt adhesive to form a sample, and the sample was fixed on a tiltable table.

After 150 seconds of loading, the table was tilted by 5° every second, and the angle at which the sample (superimposed cardboard) on the table slid down was measured to observe the state of breakage of the cardboard. Evaluation criteria are as follows.

◎: Tilt angle is 45° or more and no material destruction ○: Tilt angle is 35° or more and less than 45° and no material destruction ×: Tilt angle is less than 35° or material destruction

<Base material damage measurement>
A hot-melt adhesive melted at 180° C. was applied to a K-liner corrugated board in the form of a bead having a coating weight of 3 g/m and a length of 3 cm. After the hot-melt adhesive is completely solidified, another cardboard is placed on top of another, and a weight of 3 kg is placed on the stack of cardboard. I adjusted the time. After that, the stacked corrugated cardboards were peeled off by hand in a constant temperature bath at each temperature, and the state of the corrugated cardboards was checked to evaluate the substrate damage resistance. Evaluation criteria for corrugated substrate damage are shown below.

A: No damage.
◯: Slight fluffing.
×: Damaged

<Peelability from olefin substrate>
A hot-melt adhesive melted at 180° C. was applied to a K-liner corrugated board in the form of a bead having a coating weight of 3 g/m and a length of 3 cm. After the hot-melt adhesive was completely solidified, a polypropylene plate was placed on the hot-melt adhesive on the surface of the corrugated board, and these laminates were used as samples. A weight of 3 kg was placed on the sample, and the sample was allowed to stand in a constant temperature bath at 50°C, 23°C, and 0°C for 24 hours while the load was applied.

Thereafter, the polypropylene plate was manually peeled from the corrugated cardboard in a constant temperature bath at each temperature to confirm whether or not the hot-melt adhesive was interfacially peeled from the polypropylene plate. Evaluation criteria are as follows.

A: Interfacial peeling.
○: The hot-melt adhesive has a slight material breakage.
×: Material destruction of cardboard base material

<Exudation>
A hot-melt adhesive melted at 180° C. was applied to a K-liner corrugated board in the form of a bead having a coating weight of 3 g/m and a length of 3 cm. After the hot-melt adhesive was completely solidified, another corrugated cardboard was placed on top of another, and a weight of 3 kg was placed on the stacked corrugated cardboard and placed in a constant temperature bath at 50°C for 24 hours while a load was applied. After that, the K liner cardboard stacked in the constant temperature bath was peeled off by hand, and the state of seepage to the cardboard was evaluated. Evaluation criteria are as follows.

◎: No exudation ○: Slight exudation ×: Exudation

<Evaluation of 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 falling objects between the hot-melt gun and the adherend was visually observed to evaluate stringiness. The measurement conditions are as follows.

Temperature setting: Tank internal temperature, hose internal temperature, and nozzle internal temperature are all 180°C
Nozzle diameter: 14/1000 inch Nozzle: 1 orifice (number of outlets: 1)
Dispensing pressure: 0.3 MPa
Number of coating shots: 180 shots/1 minute

Evaluation criteria are as follows.
A: The shape of the falling object is granular.
◯: The shape of the fallen object is filamentous, but the amount of filamentous matter is small.
x: The shape of the fallen object is filamentous, and the amount of filamentous matter is large.

As shown in Tables 2 and 4, the hot melt adhesives of Examples 1 to 11 have excellent anti-slip performance, prevent damage to the cardboard substrate, and can easily separate the cardboard from the olefin substrate. . Therefore, the worker can easily unpack and transport the cardboard.

Furthermore, the hot-melt adhesives of the Examples hardly cause stringiness even when ejected from the hot-melt gun, and do not bleed onto corrugated cardboard.

In contrast, the hot-melt adhesives of Comparative Examples 1 to 5 are remarkably inferior in any of anti-slip performance, substrate damage resistance, and peelability from olefin substrates.

Since the hot-melt adhesives of Comparative Examples 1 and 2 do not contain the component (A1), they have low anti-slip performance at 50°C and damage the corrugated board substrate at 0°C.

The hot-melt adhesive of Comparative Example 3 does not contain the component (B), so the anti-slip performance at 0 to 23°C is degraded.

The hot melt adhesive of Comparative Example 4 does not contain (C) a tackifying resin, and the hot melt adhesive of Comparative Example 5 does not contain (D) wax. The hot-melt adhesives of Comparative Examples 4 and 5 are inferior in all performances and do not function as hot-melt adhesives.

The present invention provides hot melt adhesives. INDUSTRIAL APPLICABILITY The hot melt adhesive according to the present invention is useful as an adhesive for corrugated cardboard, and can prevent collapse of piled corrugated cardboard boxes, prevent damage to corrugated cardboard substrates, and easily separate corrugated cardboard from pallets. .

Claims (4)

(A) a crystalline olefin polymer, (B) an amorphous olefin polymer, (C) a tackifying resin and (D) a wax,
(A) the crystalline olefin polymer contains (A1) a metallocene-based propylene/ethylene copolymer having an ethylene content of 5 to 10% by weight;
(B) the amorphous olefin copolymer comprises (B1) a propylene/ethylene/butene copolymer,
(C) the tackifying resin comprises a hydrogenated derivative of a cycloaliphatic petroleum hydrocarbon resin;
(D) wax is a hot melt adhesive containing at least one selected from Fischer-Tropsch wax, paraffin wax, microstaline wax, polyethylene wax, and polypropylene wax ,
(A1) A hot melt adhesive in which the metallocene-based propylene/ethylene copolymer has a density of 0.87 to 0.95 g/cm ³ and a melt viscosity of 1000 to 2000 mPas at 190°C. The hot melt adhesive according to claim 1 , wherein (A1) is contained in an amount of 10 to 70 parts by weight per 100 parts by weight of the total weight of (A) to (D). 3. The hot melt adhesive according to claim 1, wherein (B1) is contained in an amount of 2 to 20 parts by weight per 100 parts by weight of the total weight of (A) to (D). A corrugated board having , on its surface, a coating film of the hot-melt adhesive according to any one of claims 1 to 3 adhered and solidified to the coated portion.