JP6900637B2 - Bookbinding - Google Patents

Description

The present invention relates to bookbinding using a moisture-curable polyurethane hot melt adhesive for adhesion.

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 (see, for example, Patent Document 1).

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, the conventional moisture-curable polyurethane hot-melt adhesive has a high viscosity, and when applied at high speed, the adhesive overflows or scatters from the glue box, and the adhesive has a low viscosity but is hard. Nothing satisfied the spreadability.

Japanese Unexamined Patent Publication No. 2000-225782

An object to be solved by the present invention is to provide bookbinding having excellent spreadability and bookbinding strength.

The present invention provides a bookbinding in which a paper leaf and a cover are adhered with an adhesive, wherein the adhesive is a foam of a moisture-curable polyurethane hot melt adhesive. is there.

The bookbinding of the present invention is excellent in spreadability and bookbinding strength. In addition, by using a foam of a moisture-curable polyurethane hot-melt adhesive as the adhesive, it has excellent coatability even when the adhesive layer is made into a thick film due to its excellent flexibility. Since the adhesive layer does not become uneven and has smoothness, the productivity of bookbinding is excellent. Further, even when a bundle of relatively thick paper sheets or a bundle of paper sheets having a coating treatment on the surface is used as the paper sheet, excellent spreadability and bookbinding strength can be obtained.

In the bookbinding of the present invention, a paper leaf and a cover are adhered with an adhesive made of a foam of a moisture-curable polyurethane hot-melt adhesive.

As the moisture-curable polyurethane hot-melt adhesive, for example, a urethane prepolymer having an isocyanate group which is a reaction product of the polyol (A) and the polyisocyanate (B) can be used.

As the polyol (A), for example, a polyether polyol (a1), a polyester polyol (a2), an acrylic polyol, a polycarbonate polyol, a polybutadiene polyol, a hydrogenated polybutadiene polyol, a dimerdiol and the like can be used. These polyols may be used alone or in combination of two or more. Among these, the polyether polyol (a1), which has excellent low viscosity and flexibility, can provide more excellent spreadability, and excellent initial strength can provide more excellent bookbinding strength. And the polyester polyol (a2) are preferably contained.

Examples of the polyether polyol (a1) include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, and polyoxypropylene polyoxy. Tetramethylene glycol or the like can be used. These polyether polyols may be used alone or in combination of two or more.

When the polyether polyol (a1) is used, the amount used is preferably in the range of 10 to 70% by mass in the polyol (A) from the viewpoint of obtaining even more excellent spreadability and bookbinding strength. The range of ~ 50% by mass is more preferable.

As the polyester polyol (a1), for example, a reaction product of a compound having two or more hydroxyl groups and a polybasic acid can be used.

Examples of the compound having two or more hydroxyl groups include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,7-heptanediol. , 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, 1,3 -Butandiol, 2,2-diethyl-1,3-propanediol, 2,2-diethylpropanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol , 2-Methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol, trimethylolethane, trimethylolpropane, pentaerythritol, trimethylolpropane, trimethylolethane, glycerin, cyclopentanediol, Aliper compounds such as cyclohexanediol and cyclohexanedimethanol; aromatic compounds such as bisphenol A, bisphenol F, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts thereof can be used. These compounds may be used alone or in combination of two or more.

Examples of the polybasic acid include succinic acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eikosaniic acid, citraconic acid, itaconic acid, citraconic anhydride, and anhydrous. An aliphatic polybasic acid such as itaconic acid; an aromatic polybasic acid such as orthophthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, biphenyldicarboxylic acid, and naphthalenedicarboxylic acid can be used. These polybasic acids may be used alone or in combination of two or more.

As the polyester polyol (a2), among the above-mentioned polyester polyols, a polyester polyol having appropriate crystallinity can be obtained, and the bubbles in the foam become finer and the bubbles are less likely to come out, so that the polyester polyol (a2) has a more beautiful finish. Since bookbinding can be obtained, it is preferable to use one having an aromatic ring, which is a reaction product of an aliphatic compound having two or more hydroxyl groups and a polybasic acid containing an aromatic polybasic acid, or having two or more hydroxyl groups. It is more preferable to use a reaction product of an aromatic compound and a polybasic acid containing an aliphatic polybasic acid. For the same reason, it is preferable to use phthalic acid as the aromatic polybasic acid, more preferably isophthalic acid and / or terephthalic acid, and sebacic acid as the aliphatic polybasic acid. Is preferably used.

When the polyester polyol (a2) is used, the amount used is preferably in the range of 10 to 80% by mass of the polyol (A) from the viewpoint of obtaining more excellent bookbinding strength, and is preferably 20 to 60% by mass. The range is more preferred.

The number average molecular weight of the polyether polyol (a1) and the polyester polyol (a2) is preferably in the range of 500 to 10,000 from the viewpoint of obtaining even more excellent spreadability and bookbinding strength. The range of 700 to 8,000 is more preferable, and the range of 800 to 5,000 is even more preferable. The number average molecular weights of the polyether polyol (a1) and the polyester polyol (a2) are values 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 ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID 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

By containing the polyether polyol (a1) and the polyester polyol (a2) as the polyol (A), more excellent spreadability and bookbinding strength can be obtained, but when the bookbinding strength is further required, Further, it is preferable to contain an acrylic polyol having an improved initial strength.

As the acrylic polyol (a-4), 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. 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 Alkylester (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, it is preferable to use the (meth) acrylic compound having a hydroxyl group and the (meth) acrylic acid alkyl ester from the viewpoint of obtaining even more excellent initial strength and bookbinding strength, and 2-hydroxyethyl (meth). ) It is preferable to use one or more (meth) acrylic compounds selected from the group consisting of acrylate, methyl (meth) acrylate and n-butyl (meth) acrylate.

The number average molecular weight of the acrylic polyol is preferably in the range of 5,000 to 50,000, preferably in the range of 10,000 to 30,000, from the viewpoint of obtaining even more excellent initial strength and bookbinding strength. Is more preferable. The number average molecular weight of the acrylic polyol indicates a value measured in the same manner as the number average molecular weight of the polyether polyol (a1) and the polyester polyol (a2).

The glass transition temperature of the acrylic polyol is preferably in the range of 30 to 120 ° C., more preferably in the range of 50 to 80 ° C., from the viewpoint of obtaining even more excellent initial strength and bookbinding strength. The glass transition temperature of the acrylic polyol is based on JISK7121-1987 and shows a value measured by DSC. Specifically, the acrylic polyol is placed in a differential scanning calorimeter device (glass transition temperature +50). The temperature is raised to 10 ° C./min, held for 3 minutes, then rapidly cooled, and the intermediate glass transition temperature (Tmg) read from the obtained differential thermal curve is shown.

When the acrylic polyol is used, the amount used is preferably in the range of 1 to 40% by mass, preferably 5 to 30% by mass in the polyol (A), from the viewpoint of obtaining even more excellent initial strength and bookbinding strength. The% range is more preferred.

Examples of the polyisocyanate (B) include aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, xylylene diisocyanate, phenylenedi isocyanate, tolylene diisocyanate, and naphthalene diisocyanate; hexamethylene 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 of the isocyanate group of the polyisocyanate (B) to the hydroxyl group of the polyol (A) (isocyanate group / hydroxyl group) 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 obtained by the above method at 120 ° C. as measured by a cone plate viscometer is 1,000 in terms of high-speed coating suitability, cutting suitability, and bookbinding strength. The range is preferably from 10,000 mPa · s, more preferably from 2,000 to 9,000 mPa · s, and even more preferably from 3,000 to 8,000 mPa · s. In the method for measuring the melt viscosity, a moisture-curable polyurethane hot-melt adhesive is melted at 120 ° C. for 1 hour, 1 ml is sampled, and melted with a cone plate viscometer (40P cone, rotor rotation speed; 50 rpm). The value obtained by measuring the viscosity is shown.

As a method of foaming the moisture-curable polyurethane hot-melt adhesive to form a foam, for example, a moisture-curable polyurethane hot-melt adhesive previously heated and melted at 100 to 140 ° C., a gear pump, and a medium-pressure foaming machine are used. , A method of injecting and mixing an inert gas such as nitrogen gas and carbon dioxide gas using a foaming machine such as Ultrafoam Mix. Further, the foam injected with the inert gas may be further refined by a mixer or the like. In the present invention, any foaming method may be used, and by going through this foaming step, excellent spreadability can be obtained by softening the adhesive layer, and stress is not concentrated, which is excellent. Bookbinding strength can be obtained. Further, even when the adhesive layer is made into a thick film, it has excellent coatability, and since the adhesive layer has smoothness without becoming uneven, bookbinding can be obtained with good productivity.

As a method of binding with a moisture-curable polyurethane hot-melt adhesive foamed as described above, for example, the adhesive is applied to a bonding surface of a bundle of a plurality of paper sheets and / or a bonding surface of a cover. An example is a method of applying and pasting the paper leaf and the cover.

As the paper leaf, for example, art paper, coated paper, matte paper, high-quality paper, medium-quality paper, or the like can be used. These paper sheets may be used alone or in combination of two or more. In the present invention, by using a foam of a moisture-curable polyurethane hot melt adhesive as the adhesive, a bundle of relatively thick paper sheets or art paper, which is generally said to have difficulty in binding strength, or art paper. It is also possible to obtain excellent spreadability and bookbinding strength by using a bundle of paper sheets whose surface is coated, such as coated paper. As the relatively thick paper leaf, for example, the thickness of one sheet of paper is in the range of 0.1 to 0.5 mm, preferably in the range of 0.11 to 0.3 mm, and more preferably 0. It is in the range of .12 to 0.2 mm.

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.

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.

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

The density of the moisture-curable polyurethane hot-melt adhesive layer having a foamed structure obtained by the above method is 0.1 to 0.8 g / cm ³ from the viewpoint of appearance, coatability, adhesiveness and mechanical strength. It is preferably in the range, more preferably in the range of 0.2 to 0.6 g / cm ^3.

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

[Example 1]
Polyester polyol (1,6-hexanediol, terephthalic acid, and sebacic acid reacted in a four-necked flask equipped with a stirrer and a thermometer, number average molecular weight: 2,000, hereinafter "HG / tPA / SebA" (Abbreviated as "PPG") is 30 parts by mass, polyoxypropylene glycol (number average molecular weight: 1,000, hereinafter abbreviated as "PPG") is 34 parts by mass, acrylic polyol (methyl methacrylate, n-butyl methacrylate and 2). A polymer of −hydroxyethyl methacrylate, number average molecular weight; 20,000, hereinafter abbreviated as “MMA / BMA / HEMA”) is added in an amount of 15 parts by mass, mixed, and heated under reduced pressure at 100 ° C. to increase the water content in the flask. Was dehydrated to 0.05% by mass. After cooling the inside of the flask to 90 ° C., add 21 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. By reacting at 110 ° C. for about 3 hours, a urethane prepolymer (melt viscosity at 120 ° C.; 4,500 mPa · s, NCO%: 2.6% by mass) was obtained, and a moisture-curable polyurethane hot melt adhesive was obtained.
Next, the obtained moisture-curable polyurethane hot-melt adhesive was foamed at a foaming ratio of 3 times using "Ultra Foam Mix Cube" manufactured by Nordson Co., Ltd., and 100 sheets of paper (art paper, 1 sheet of thickness) were foamed. (S: 0.15 mm) was applied to the side surface of the bundle to a thickness of 1 mm, bonded to the cover, and then left to stand for 2 days under the conditions of 23 ° C. and 50% humidity to obtain a bookbinding sample.

[Examples 2 to 3]
A moisture-curable polyurethane hot-melt adhesive was obtained in the same manner as in Example 1 except that the type and amount of the polyol (A) used were changed as shown in Table 1, and a bookbinding sample was obtained.

[Example 4]
A moisture-curable polyurethane hot-melt adhesive was obtained in the same manner as in Example 1 except that the paper leaf to be used was changed to one piece of high-quality paper having a thickness of 0.09 mm, and a bookbinding sample was obtained.

[Example 5]
A moisture-curable polyurethane hot-melt adhesive was obtained in the same manner as in Example 2 except that the paper leaf to be used was changed to one piece of high-quality paper having a thickness of 0.09 mm, and a bookbinding sample was obtained.

[Example 6]
A moisture-curable polyurethane hot-melt adhesive was obtained in the same manner as in Example 3 except that the paper leaf used was changed to one piece of high-quality paper having a thickness of 0.09 mm, and a bookbinding sample was obtained.

[Comparative Example 1]
A bookbinding sample was obtained in the same manner as in Example 4 except that the moisture-curable polyurethane hot-melt adhesive was used without foaming.

[Evaluation method of spreadability]
The bookbinding samples obtained in Examples and Comparative Examples were 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 it, the book will close.

[Evaluation method of bookbinding strength]
For the bookbinding samples obtained in Examples and Comparative Examples, 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).

The abbreviations in Table 1 indicate the following.
"BisA (6PO) / iPA / SebA": 6 mol adduct of propylene oxide of bisphenol A, isophthalic acid, and sebacic acid reacted, number average molecular weight: 2,000

It was found that the bookbinding of the present invention has excellent bookbinding properties and bookbinding strength.

On the other hand, Comparative Example 1 was a mode in which the moisture-curable polyurethane hot-melt adhesive was not foamed, but both the spreadability and the bookbinding strength were poor.

Claims (2)

A binding that is glued to the paper sheets and cover, wherein the adhesive, Ri foam der moisture-curable polyurethane hot melt adhesive,
The moisture-curable polyurethane hot-melt adhesive contains a urethane prepolymer having an isocyanate group which is a reaction product of a polyol (A) and a polyisocyanate (B).
The polyol (A) contains a polyether polyol (a1), a polyester polyol (a2) having an aromatic ring, and an acrylic polyol.
The density of the adhesive layer, wherein the range der Rukoto of 0.1 to 0.8 g / cm ³ binding. The polyester polyol (a2) is a reaction product of an aliphatic compound having two or more hydroxyl groups and a polybasic acid containing an aromatic polybasic acid, or an aromatic compound having two or more hydroxyl groups and an aliphatic polybasic acid. binding according to claim 1, which is a reaction product of a polybasic acid containing.