JP6759740B2 - Moisture-curable polyurethane hot-melt adhesive and bookbinding adhesive - Google Patents

Description

The present invention relates to a moisture-curable polyurethane hot melt adhesive that can be particularly preferably used as a bookbinding adhesive.

Bookbinding adhesives are widely used to bond paper sheets and covers used in bookbinding, and are EVA (ethylene-vinyl acetate copolymer) adhesives and moisture-curable polyurethane hot-melt adhesives (RHM). ) Make up the majority.

However, the EVA adhesives known so far need to have a thick coating film in order to exhibit a satisfactory adhesive strength, and as a result, there is a problem that the spreadability of bookbinding is poor.

On the other hand, conventional moisture-curable polyurethane hot-melt adhesives have high viscosity, and when applied at high speed, the adhesive overflows or scatters from the glue box, and there are only low-viscosity but hard adhesives, all of which are suitable for high-speed application. , No one satisfied all of the cutting suitability and the spreadability. Further, since the conventional moisture-curable polyurethane hot-melt adhesive has a low initial strength, there is a problem that the adhesive layer is deformed in the transport process and the paper leaves are displaced when binding a heavy book.

Japanese Unexamined Patent Publication No. 2000-225782

An object to be solved by the present invention is to provide a moisture-curable polyurethane hot-melt adhesive having excellent high-speed coating suitability, cutting suitability, spreadability, initial strength, and bookbinding strength.

The present invention relates to a crystalline polyester polyol (a-1), a polyoxyethylene polyoxypropylene glycol (a-2), a polyether polyol (a-3) other than the above (a-2), and an acrylic polyol (a-4). ) And a urethane prepolymer having an isocyanate group, which is a reaction product of the polyol (A) containing the polycaprolactone polyol (a-5) and the polyisocyanate (B), which is a moisture-curable polyurethane hot melt. The present invention relates to an adhesive and a book-binding adhesive comprising the moisture-curable polyurethane hot-melt adhesive.

The moisture-curable polyurethane hot-melt adhesive of the present invention is excellent in high-speed coating suitability, cutting suitability, spreadability, initial strength, and bookbinding strength. Therefore, the moisture-curable polyurethane hot-melt adhesive of the present invention is very suitable as a so-called bookbinding adhesive that adheres a paper leaf and a cover. In particular, the moisture-curable polyurethane hot-melt adhesive of the present invention has excellent bookbinding strength (hereinafter referred to as "low-temperature bookbinding strength") when the paper leaf and the cover are adhered even at a low temperature (60 to 100 ° C.). It is abbreviated.) Is obtained. In addition, the moisture-curable polyurethane hot-melt adhesive of the present invention has excellent initial strength and is therefore suitable for binding heavy books. In addition, the moisture-curable polyurethane hot-melt adhesive of the present invention also has an appropriate open time (stickable time), and is used not only for bookbinding, but also for fiber bonding / building material lamination and bonding of optical members. Can also be suitably used.

The moisture-curable polyurethane hot-melt adhesive of the present invention includes a crystalline polyester polyol (a-1), a polyoxyethylene polyoxypropylene glycol (a-2), and a polyether polyol (a-) other than the above (a-2). 3) A urethane prepolymer having an isocyanate group, which is a reaction product of a polyol (A) containing an acrylic polyol (a-4) and a polycaprolactone polyol (a-5) and a polyisocyanate (B). is there.

The crystalline polyester polyol (a-1) is an essential component for obtaining excellent bookbinding strength, initial hardness, flexibility and low viscosity. For example, a reaction product of a compound having a hydroxyl group and a polybasic acid can be used. Can be used. In the present invention, "crystallinity" means that the peak of heat of crystallization or heat of fusion can be confirmed in DSC (differential scanning calorimetry) measurement based on JISK7121: 2012, and is referred to as "amorphous". Indicates that the peak cannot be confirmed.

As the compound having a hydroxyl group, for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, glycerin and the like can be used. Can be done. These compounds may be used alone or in combination of two or more. Among these, butanediol, hexanediol, octanediol, and decanediol are preferably used from the viewpoint of increasing crystallinity and further improving adhesive strength.

As the polybasic acid, for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and dodecanedioic acid can be used. These polybasic acids may be used alone or in combination of two or more.

The number average molecular weight of the crystalline polyester polyol (a-1) is preferably in the range of 500 to 10,000, preferably 1,000 to 8,000, from the viewpoint of further improving the open time and the bookbinding strength. The range of is more preferable. The number average molecular weight of the crystalline polyester polyol (a-1) is a value measured under the following conditions by a gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series and used.
"TSKgel G5000" (7.8 mm I.D. x 30 cm) x 1 "TSKgel G4000" (7.8 mm I.D. x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 This "TSKgel G2000" (7.8 mm ID x 30 cm) x 1 Detector: RI (Differential Refractometer)
Column temperature: 40 ° C
Eluent: tetrahydrofuran (THF)
Flow velocity: 1.0 mL / min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

The glass transition temperature of the crystalline polyester polyol (a-1) is preferably in the range of 40 to 130 ° C. from the viewpoint of obtaining even more excellent bookbinding strength, initial hardness, flexibility and low viscosity. .. The glass transition temperature of the crystalline polyester polyol (a-1) is based on JISK7121-1987 and shows a value measured by DSC. Specifically, the crystalline polyester is placed in a differential scanning calorimeter device. The polyol (a-1) was added, the temperature was raised to (glass transition temperature + 50 ° C.) at a heating rate of 10 ° C./min, held for 3 minutes, then rapidly cooled, and the intermediate point read from the obtained differential thermal curve. The glass transition temperature (Tmg) is shown.

The amount of the crystalline polyester polyol (a-1) used is in the range of 10 to 70% by mass in the polyol (A) from the viewpoint of obtaining even more excellent bookbinding strength, initial hardness, flexibility and low viscosity. Is preferable, and the range of 30 to 60% by mass is more preferable.

The polyoxyethylene polyoxypropylene glycol (a-2) is an essential component in that an extremely excellent initial strength and bookbinding strength at low temperature can be obtained by improving the permeability to a base material. As the molar ratio [EO / PO] of the oxyethylene group to the oxypropylene group in the polyoxyethylene polyoxypropylene glycol (a-2), even more excellent initial strength and bookbinding strength can be obtained. The range is preferably 3/97 to 80/20, and more preferably 5/95 to 70/30.

The number average molecular weight of the polyoxyethylene polyoxypropylene glycol (a-2) is preferably in the range of 700 to 10,000 from the viewpoint of obtaining even more excellent initial strength and bookbinding strength at low temperature. , 1,000 to 5,000 are more preferred. The number average molecular weight of the polyoxyethylene polyoxypropylene glycol (a-2) indicates a value obtained by measuring in the same manner as the number average molecular weight of the crystalline polyester polyol (a-1).

The amount of the polyoxyethylene polyoxypropylene glycol (a-2) used is in the range of 5 to 30% by mass in the polyol (A) from the viewpoint of obtaining even more excellent initial strength and bookbinding strength at low temperature. It is preferably in the range of 7 to 20% by mass, and more preferably.

Polyether polyols (a-3) other than the above (a-2) are essential components for obtaining excellent bookbinding strength, film flexibility and low viscosity, and are, for example, polyethylene glycol, polypropylene glycol and polybutylene. Glycol, polytetramethylene glycol and the like can be used. These polyether polyols may be used alone or in combination of two or more. Among these, polypropylene glycol is preferably used from the viewpoint of obtaining even more excellent bookbinding strength, film flexibility and low viscosity.

The number average molecular weight of the polyether polyol (a-3) is preferably in the range of 200 to 10,000 from the viewpoint of obtaining even more excellent bookbinding strength, film flexibility and low viscosity, and is preferably 400. The range of ~ 8,000 is more preferable, and the range of 500 to 3,000 is even more preferable. The number average molecular weight of the polyether polyol (a-3) shows a value measured in the same manner as the number average molecular weight of the crystalline polyester polyol (a-1).

The amount of the polyether polyol (a-3) used should be in the range of 10 to 60% by mass in the polyol (A) from the viewpoint of obtaining even more excellent bookbinding strength, film flexibility and low viscosity. Is preferable, and the range of 20 to 40% by mass is more preferable.

The acrylic polyol (a-4) is an essential component for obtaining excellent initial strength. For example, a polymer of a (meth) acrylic compound containing a (meth) acrylic compound having a hydroxyl group as an essential component can be used. it can. In the present invention, "(meth) acrylic compound" means a methacrylic compound and / or an acrylic compound, and "(meth) acrylate" means methacrylate and / or acrylate, and "(meth) acrylic acid". Indicates methacrylic acid and / or acrylic acid.

Examples of the (meth) acrylic compound having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol tetra (meth). ) Acrylate or the like can be used. These compounds may be used alone or in combination of two or more.

Examples of other (meth) acrylic compounds include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and tert-butyl (meth). Acrylate, neopentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cetyl (meth) acrylate, lauryl (meth) acrylate, etc. (Meta) Acrylic Acid Alkester (Meta) Acrylic Acid Alkyl Acrylate; 2,2,2-trifluoroethyl (meth) Acrylate, 2,2,3,3-Tetrafluoropropyl (Meta) Acrylate, 1H, 1H, 5H -A (meth) acrylic compound having a fluorine atom such as octafluoropentyl (meth) acrylate and 2- (perfluorooctyl) ethyl (meth) acrylate; isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, sidiclopentanyl ( (Meta) acrylic compounds having an alicyclic structure such as meta) acrylate and dicyclopentenyloxyethyl (meth) acrylate; polyethylene glycol mono (meth) acrylate, methoxyethyl (meth) acrylate, methoxybutyl (meth) acrylate, methoxytri (Meta) acrylic compounds having ether groups such as ethylene glycol (meth) acrylate and methoxypolyethylene glycol (meth) acrylate; benzyl (meth) acrylate, 2-ethyl-2-methyl- [1,3] -dioxolan-4- Il-methyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and the like can be used. These (meth) acrylic compounds may be used alone or in combination of two or more. Among these, the (meth) acrylic compound having a hydroxyl group and the (meth) acrylic acid alkyl ester are preferably used from the viewpoint of further improving the open time and the adhesive strength, and 2-hydroxyethyl (meth) acrylate, It is preferable to use one or more (meth) acrylic compounds selected from the group consisting of methyl (meth) acrylate and n-butyl (meth) acrylate.

The number average molecular weight of the acrylic polyol (a-4) is preferably in the range of 5,000 to 50,000 from the viewpoint of further improving the open time and the initial strength, and is preferably 10,000 to 30,000. The range of is more preferable. The number average molecular weight of the acrylic polyol (a-4) indicates a value measured in the same manner as the number average molecular weight of the crystalline polyester polyol (a-1).

The glass transition temperature of the acrylic polyol (a-4) is preferably in the range of 30 to 120 ° C., more preferably in the range of 50 to 80 ° C., from the viewpoint of further improving the open time and the initial strength. The glass transition temperature of the acrylic polyol (a-4) shows a value measured in the same manner as the glass transition temperature of the crystalline polyester polyol (a-1).

The amount of the acrylic polyol (a-4) used is preferably in the range of 1 to 20% by mass, preferably 3 to 10% by mass, in the polyol (A), from the viewpoint of further improving the open time and the initial strength. The range of is more preferable.

The polycaprolactone polyol (a-5) is an essential component for obtaining excellent initial strength, and for example, a reaction product of the above-mentioned compound having a hydroxyl group and ε-caprolactone can be used.

The number average molecular weight of the polycaprolactone polyol (a-5) is preferably in the range of 5,000 to 200,000 from the viewpoint of further improving the open time and the initial strength. A range of 000 is more preferred.

The amount of the polycaprolactone polyol (a-5) used is preferably in the range of 1 to 20% by mass in the polyol (A), preferably 3 to 15% by mass, from the viewpoint of further improving the open time and the initial strength. The% range is more preferred.

The polyol (A) is a crystalline polyester polyol (a-1), a polyoxyethylene polyoxypropylene glycol (a-2), a polyether polyol (a-3) other than the above (a-2), and an acrylic polyol (a). It contains a-4) and polycaprolactone polyol (a-5), but other polyols may be contained if necessary.

As the other polyol, for example, an amorphous polyester polyol, a polybutadiene polyol, a polyisoprene polyol and the like can be used. These polyols may be used alone or in combination of two or more.

Examples of the polyisocyanate (B) include aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, xylylene diisocyanate, phenylenedi isocyanate, tolylene diisocyanate, and naphthalene diisocyanate; , Cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate and other aliphatic or alicyclic polyisocyanates can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, from the viewpoint of reactivity and adhesive strength, it is preferable to use aromatic polyisocyanate, and it is more preferable to use diphenylmethane diisocyanate.

The urethane prepolymer is obtained by reacting the polyol (A) with the polyisocyanate (B), and reacts with water existing in the air or in the base material to which the urethane prepolymer is applied. It has an isocyanate group capable of forming a crosslinked structure.

As a method for producing the urethane prepolymer, for example, a mixture of the polyol (A) is added dropwise to a reaction vessel containing the polyisocyanate (B) and then heated to form an isocyanate group contained in the polyisocyanate (B). , Can be produced by reacting with the hydroxyl group of the polyol (A) under conditions that are excessive.

When producing the urethane prepolymer, the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group of the polyisocyanate (B) to the hydroxyl group of the polyol (A) further improves the adhesive strength and flexibility. From the point of view, the range of 1.1 to 5 is preferable, and the range of 1.5 to 3 is more preferable.

The isocyanate group content of the urethane prepolymer obtained by the above method (hereinafter, abbreviated as "NCO%") shall be in the range of 1.7 to 5 from the viewpoint of further improving the adhesive strength. Is preferable, and the range of 1.8 to 3 is more preferable. The NCO% of the urethane prepolymer is a value measured by the potentiometric titration method in accordance with JISK1603-1: 2007.

The moisture-curable polyurethane hot-melt adhesive contains the urethane prepolymer, but may contain other additives as needed.

Examples of the other additives include curing catalysts, antioxidants, tackifiers, plasticizers, stabilizers, fillers, dyes, pigments, fluorescent whitening agents, silane coupling agents, waxes, thermoplastic resins and the like. Can be used. These additives may be used alone or in combination of two or more.

The melt viscosity of the moisture-curable polyurethane hot-melt adhesive of the present invention obtained by the above method at 120 ° C. as measured by a cone plate viscometer is 1 from the viewpoint of high-speed coating suitability, cutting suitability and bookbinding strength. The range is preferably in the range of 000 to 10,000 mPa · s, more preferably in the range of 2,000 to 9,000 mPa · s, and even more preferably in the range of 3,000 to 8,000 mPa · s. The method for measuring the melt viscosity will be described in detail in Examples described later.

After applying the moisture-curable polyurethane hot-melt adhesive in an atmosphere of 23 ° C. and leaving it for 30 minutes, the JISA hardness is 20 or more from the viewpoint of obtaining even better high-speed coating suitability, cutting suitability and bookbinding strength. It is preferably in the range of 23 to 90, more preferably in the range of 25 to 80. The method for measuring the JISA hardness will be described in detail in Examples described later.

The JISA hardness after applying the moisture-curable polyurethane hot-melt adhesive in an atmosphere of 23 ° C. and leaving it for 30 minutes and then leaving it in an atmosphere of 23 ° C. and 50% humidity for 1 week is even more excellent. From the viewpoint of obtaining the spreadability of bookbinding, it is preferably 95 or less, and more preferably 50 to 90. The method for measuring the JISA hardness will be described in detail in Examples described later.

The top yield point stress of the cured film of the moisture-curable polyurethane hot-melt adhesive is preferably 7 MPa or less, and more preferably 3 to 6 MPa, from the viewpoint of bookbinding spreadability. The method for measuring the upper yield point stress will be described in detail in Examples described later.

As described above, the moisture-curable polyurethane hot-melt adhesive of the present invention is excellent in high-speed coating suitability, cutting suitability, spreadability, initial strength, and bookbinding strength. Therefore, the moisture-curable polyurethane hot-melt adhesive of the present invention is very suitable as a so-called bookbinding adhesive that adheres a paper leaf and a cover.

As a method of binding with the moisture-curable polyurethane hot-melt adhesive of the present invention, for example, the adhesive is applied to the bonded surface of a bundle of a plurality of paper sheets and / or the bonded surface of a cover, and the paper leaves. There is a method of pasting the cover and the cover.

Examples of the method of applying the adhesive to the bonded surfaces include coater methods such as roll coaters, spray coaters, T-die coaters, knife coaters, and comma coaters; dispensers, inkjet printing, screen printing, offset printing, and the like. Precision method; Nozzle coating or the like can be used.

Generally, when a moisture-curable polyurethane hot-melt adhesive is applied to the bonded surface, the moisture-curable polyurethane hot-melt adhesive is melted at a temperature of, for example, 100 to 140 ° C. in order to obtain excellent bookbinding strength. Is preferable. In the present invention, excellent bookbinding strength can be obtained even if the moisture-curable polyurethane hot-melt adhesive is melted at a temperature of, for example, 60 to 100 ° C. As a result, excellent bookbinding strength can be exhibited even when the paper temperature is low, such as in winter, and there are merits that energy consumption can be reduced by lowering the temperature of the coating device and the thickening of polyurethane hot melt over time can be suppressed.

After the paper leaf and the cover are bonded together, it is preferable to perform drying and curing by a known method according to the type of adhesive used.

With the adhesive, the thickness of the adhesive layer can be appropriately determined, for example, in the range of 0.001 to 0.5 cm.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[Example 1]
Crystalline polyester polyol (reaction of 1,6-hexanediol and dodecanedioic acid, number average molecular weight; 3,500, hereinafter "HG / DDA3500") in a four-necked flask equipped with a stirrer and a thermometer. Is abbreviated as 36 parts by mass, and polyoxyethylene polyoxypropylene glycol (number average molecular weight; 4,000, [EO / PO] = 10/90, hereinafter abbreviated as “EOPO4000”) is 10 parts by mass. 26 parts by mass of polypropylene glycol (number average molecular weight; 1,000. Hereinafter, abbreviated as "PPG1000"), acrylic polyol (methyl methacrylate, n-butyl methacrylate and 2-hydroxyethyl methacrylate polymerized, number average) Molecular weight: 20,000, hereinafter abbreviated as "MMA / BMA / HEMA20000") by 5 parts by mass, polycaprolactone polyol (number average molecular weight: 80,000, hereinafter abbreviated as "PCL80000") by 5 parts by mass. The mixture was mixed in parts, heated under reduced pressure at 100 ° C., and dehydrated until the water content in the flask reached 0.05% by mass. After cooling the inside of the flask to 90 ° C., add 18 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI") melted at 70 ° C. until the NCO% becomes constant under a nitrogen atmosphere. A urethane prepolymer was obtained by reacting at 110 ° C. for about 3 hours to obtain a moisture-curable polyurethane hot melt adhesive.

[Example 2]
In a 4-neck flask equipped with a stirrer and a thermometer, 32 parts by mass of HG / DDA3500, 10 parts by mass of EOPO4000, 26 parts by mass of PPG1000, 5 parts by mass of MMA / BMA / HEMA20000, and polycaprolactone polyol (number average molecular weight). 40,000, hereinafter abbreviated as "PCL40000") was added in 10 parts by mass, mixed, heated under reduced pressure at 100 ° C., and dehydrated until the water content in the flask became 0.05% by mass.
After cooling the inside of the flask to 90 ° C., 17 parts by mass of MDI melted at 70 ° C. was added, and the mixture was reacted at 110 ° C. for about 3 hours in a nitrogen atmosphere until the NCO% became constant to obtain a urethane prepolymer. A curable polyurethane hot melt adhesive was obtained.

[Example 3]
In a 4-necked flask equipped with a stirrer and a thermometer, 21 parts by mass of HG / DDA3500, a crystalline polyester polyol (reactant of 1,6-hexanediol and adipic acid, number average molecular weight; 3,500, hereinafter " HG / AA3500 ”is abbreviated as 15 parts by mass, EOPO4000 by 10 parts by mass, PPG1000 by 26 parts by mass, MMA / BMA / HEMA20000 by 5 parts by mass, PCL80000 by 5 parts by mass, mixed, and heated under reduced pressure at 100 ° C. Then, the flask was dehydrated until the water content in the flask reached 0.05% by mass.
After cooling the inside of the flask to 90 ° C., 18 parts by mass of MDI melted at 70 ° C. was added, and the mixture was reacted at 110 ° C. for about 3 hours in a nitrogen atmosphere until the NCO% became constant to obtain a urethane prepolymer. A curable polyurethane hot melt adhesive was obtained.

[Example 4]
In a 4-neck flask equipped with a stirrer and a thermometer, 16 parts by mass of HG / DDA3500, 16 parts by mass of HG / AA3500, 10 parts by mass of EOPO4000, 26 parts by mass of PPG1000, and 5 parts by mass of MMA / BMA / HEMA20000. , PCL40000 was added in an amount of 10 parts by mass, mixed, heated under reduced pressure at 100 ° C., and dehydrated until the water content in the flask became 0.05% by mass.
After cooling the inside of the flask to 90 ° C., 17 parts by mass of MDI melted at 70 ° C. was added, and the mixture was reacted at 110 ° C. for about 3 hours in a nitrogen atmosphere until the NCO% became constant to obtain a urethane prepolymer. A curable polyurethane hot melt adhesive was obtained.

[Comparative Example 1]
In a 4-neck flask equipped with a stirrer and a thermometer, 35 parts by mass of HG / DDA3500, 26 parts by mass of PPG1000, 5 parts by mass of MMA / BMA / HEMA20000 and 5 parts by mass of PCL80000 are put and mixed, and the pressure is reduced at 100 ° C. It was heated and dehydrated until the water content in the flask reached 0.05% by mass.
After cooling the inside of the flask to 90 ° C., 19 parts by mass of MDI melted at 70 ° C. was added, and the mixture was reacted at 110 ° C. for about 3 hours in a nitrogen atmosphere until the NCO% became constant to obtain a urethane prepolymer. Obtained curable polyurethane hot melt adhesive

[Comparative Example 2]
In a 4-neck flask equipped with a stirrer and a thermometer, 41 parts by mass of HG / DDA3500, 10 parts by mass of EOPO4000, 26 parts by mass of PPG1000, and 5 parts by mass of MMA / BMA / HEMA20000 are put and mixed, and the pressure is reduced at 100 ° C. It was heated and dehydrated until the water content in the flask reached 0.05% by mass.
After cooling the inside of the flask to 90 ° C., 18 parts by mass of MDI melted at 70 ° C. was added, and the mixture was reacted at 110 ° C. for about 3 hours in a nitrogen atmosphere until the NCO% became constant to obtain a urethane prepolymer. A curable polyurethane hot melt adhesive was obtained.

[Comparative Example 2]
In a 4-neck flask equipped with a stirrer and a thermometer, 40 parts by mass of HG / DDA3500, 36 parts by mass of PPG1000, and 5 parts by mass of MMA / BMA / HEMA20000 are put and mixed, and heated under reduced pressure at 100 ° C. in the flask. It was dehydrated until the water content became 0.05% by mass.
After cooling the inside of the flask to 90 ° C., 19 parts by mass of MDI melted at 70 ° C. was added, and the mixture was reacted at 110 ° C. for about 3 hours in a nitrogen atmosphere until the NCO% became constant to obtain a urethane prepolymer. A curable polyurethane hot melt adhesive was obtained.

[Measurement method of melt viscosity at 120 ° C]
The moisture-curable polyurethane hot-melt adhesives obtained in Examples and Comparative Examples were melted at 120 ° C. for 1 hour, 1 ml was sampled, and the melt viscosity was measured with a cone plate viscometer (40P cone, rotor speed; 50 rpm). Was measured.

[Measurement method of JISA hardness]
The moisture-curable polyurethane hot-melt adhesive obtained in Examples and Comparative Examples was melted at 120 ° C. for 1 hour, and then poured into a cylindrical mold having a diameter of 56 mm and a height of 8 mm in an atmosphere of 23 ° C. for 30 minutes. The JISA hardness (initial hardness) of the surface of the cylindrical molded product after being left to stand, and then the JISA hardness (final hardness) of the surface of the cylindrical molded product after being left to stand in an atmosphere of 23 ° C. and 50% humidity for 1 week. Measured according to 1996.

[Measurement method of upper yield point stress]
After melting the moisture-curable polyurethane hot-melt adhesive obtained in Examples and Comparative Examples at 120 ° C., an applicator was used so that the thickness after application on the release-treated polyethylene terephthalate film was 100 μm. And applied. Then, it was left for one week under the condition of 23 ° C. and 50% humidity to obtain a cured film of a moisture-curable polyurethane hot melt adhesive. The top yield point stress (MPa) of the obtained cured film having a thickness of 100 μm was measured according to JIS K7311-1995.

[Evaluation method of high-speed application suitability]
The moisture-curable polyurethane hot-melt adhesive obtained in Examples and Comparative Examples was melted at 120 ° C., placed between two roll coaters, rotated at a speed of 50 m / min, and glued from both ends of the roll. The adhesive that did not overflow was evaluated as "T" for high-speed application suitability, and the adhesive that overflowed was evaluated as "F".

[Evaluation method of cutting suitability]
The moisture-curable polyurethane hot-melt adhesive obtained in Examples and Comparative Examples was melted at 120 ° C., applied on paper using an applicator to a thickness of 400 μm, left for 5 minutes, and then cut with a cutting machine. , It was visually confirmed whether or not there was adhesive residue on the blade. The cutting suitability was evaluated as "T" when there was no adhesive residue on the blade, and "F" when there was adhesive residue.

[Evaluation method of initial strength]
The moisture-curable polyurethane hot-melt adhesives obtained in Examples and Comparative Examples were melted at 120 ° C. for 1 hour, and then coated on a 0.25 mm-thick cover using an applicator to a thickness of 400 μm. , Attach a bundle of 100 sheets of paper (high-quality paper, thickness of one sheet; 0.09 mm) to the coated surface, and after 5 minutes, use the precision universal testing machine "AG-10NX" manufactured by Shimadzu Corporation. The adhesive strength (N / 25 mm) was measured using the product, and the initial strength was evaluated as follows.
"T": The adhesive strength is 8 (N / 25 mm) or more.
"F": The adhesive strength is less than 8 (N / 25 mm).

[Method 1 for preparing a bookbinding sample]
The moisture-curable polyurethane hot-melt adhesives obtained in Examples and Comparative Examples were melted at 120 ° C. for 1 hour, and then coated on a 0.25 mm-thick cover using an applicator to a thickness of 400 μm. The adhesive coated surface is adjusted to 120 ° C., and a bundle of 100 sheets of paper (high quality paper, one sheet thickness; 0.09 mm) is attached to the coated surface, and then at 23 ° C. and 50% humidity. It was left to stand for 2 days under the conditions to obtain a bound sample.

[Method for producing bookbinding sample 2]
The moisture-curable polyurethane hot-melt adhesives obtained in Examples and Comparative Examples were melted at 120 ° C. for 1 hour, and then coated on a 0.25 mm-thick cover using an applicator to a thickness of 400 μm. Adjust the adhesive-coated surface to 80 ° C, attach a bundle of 100 sheets of paper (high-quality paper, one sheet thickness; 0.09 mm) to the coated surface, and then attach a bundle of 100 sheets of paper (high-quality paper, thickness of one sheet; 0.09 mm) to the coated surface at 23 ° C. and 50% humidity. It was left to stand for 2 days under the conditions to obtain a bound sample.

[Evaluation method of spreadability]
The bookbinding sample obtained in Method 1 for producing a bookbinding sample was opened by hand and the spreadability was evaluated as follows.
"T": After opening the book, the book does not close and the paper leaves do not rise even if left unattended.
"F": After opening the book, if you release your hand, the book will close.

[Evaluation method of bookbinding strength (adhesive temperature 120 ° C)]
For the bookbinding sample obtained in Method 1 of the bookbinding sample, the adhesive strength (N / 25 mm) was measured using the precision universal testing machine "AG-10NX" manufactured by Shimadzu Corporation, and the bookbinding strength was as follows. It was evaluated as.
"T": The adhesive strength is 30 (N / 25 mm) or more.
"F": The adhesive strength is less than 30 (N / 25 mm).

[Evaluation method of bookbinding strength at low temperature (bookbinding strength (adhesive temperature 80 ° C))]
For the bookbinding sample obtained in Method 2 of the bookbinding sample, the adhesive strength (N / 25 mm) was measured using the precision universal testing machine "AG-10NX" manufactured by Shimadzu Corporation, and the bookbinding strength was as follows. It was evaluated as.
"T": The adhesive strength is 30 (N / 25 mm) or more.
"F": The adhesive strength is less than 30 (N / 25 mm).

It was found that the bookbinding adhesive of the present invention is excellent in high-speed application suitability, cutting suitability, spreadability, initial strength, and bookbinding strength.

On the other hand, Comparative Example 1 was an embodiment in which polyoxyethylene polyoxypropylene glycol (a-2) was not used, but the bookbinding strength at low temperature was insufficient.

Further, Comparative Example 2 was an embodiment in which polycaprolactone polyol (a-5) was not used, but the initial strength was poor.

Comparative Example 3 is an embodiment in which polyoxyethylene polyoxypropylene glycol (a-2) and polycaprolactone polyol (a-5) are not used, but the initial strength and the bookbinding strength at low temperature are poor.

Claims (2)

Crystalline polyester polyol (a-1), polyoxyethylene polyoxypropylene glycol (a-2), polyether polyol (a-3) other than the above (a-2), acrylic polyol (a-4) and polycaprolactone. A moisture-curable polyurethane hot melt adhesive characterized by containing a urethane prepolymer having an isocyanate group which is a reaction product of a polyol (A) containing a polyol (a-5) and a polyisocyanate (B). An adhesive for bookbinding, which comprises the moisture-curable polyurethane hot-melt adhesive according to claim 1.