JP7310162B2 - Moisture-curing hot-melt adhesive and adhesive - Google Patents

Description

The present invention relates to a moisture-curable hot-melt adhesive and an adhesive body.

Hot-melt adhesives are non-solvent adhesives, so they are less harmful to the environment and the human body, and can be adhered in a short period of time, making them suitable for improving productivity. Hot-melt adhesives can be broadly classified into those containing a thermoplastic resin as a main component and those containing a reactive resin as a main component. Urethane prepolymers having isocyanate groups at their terminals are mainly used as reactive resins. A reactive hot-melt adhesive containing urethane prepolymer as a main component can exhibit a certain degree of adhesive strength (initial adhesiveness) in a short period of time by cooling and solidifying the adhesive itself after application. After that, the terminal isocyanate groups of the urethane prepolymer react with moisture in the air or moisture on the surface of the adherend to increase the molecular weight and cause cross-linking, thereby curing the adhesive and exhibiting adhesiveness. Such an adhesive is called a "moisture-curable hot-melt adhesive". Moisture-curable hot-melt adhesives containing urethane prepolymer as a main component tend to exhibit good adhesive strength even when heated.

In addition, in order to improve the adhesiveness of moisture-curable hot-melt adhesives, the use of urethane prepolymers having a structure derived from a rosin compound having a hydroxyl group has been investigated (see, for example, Patent Documents 1 to 3). .

JP-A-4-198387 JP-A-2003-89782 JP 2010-126615 A

In recent years, moisture-curable hot-melt adhesives are being used for cloth, paper, etc., which are materials for clothes, diapers, and the like. From the viewpoint of workability, adhesives used in the joints of clothes such as sportswear and innerwear must exhibit adhesiveness immediately after adhering cloths together and have excellent adhesiveness after moisture curing. is required. Moreover, such an adhesive is required to form a hardened product having excellent flexibility in order to improve the wearing comfort in addition to adhesiveness to cloth.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide a moisture-curable hot-melt adhesive that exhibits high initial adhesiveness and excellent flexibility after curing.

One aspect of the present invention is a urethane prepolymer having a polyurethane chain containing a polyol-derived structural unit and a polyisocyanate-derived structural unit, a urethane prepolymer having an isocyanate group bonded to the end of the polyurethane chain, and a rosin compound having no hydroxyl group. and a moisture-curable hot-melt adhesive containing

The polyol may contain at least one selected from the group consisting of polybutadiene polyol and hydrogenated polybutadiene polyol. Polyols may also include hydrogenated polybutadiene polyols.

The content of the rosin compound may be 65% by mass or less based on the total mass of the polyol and the rosin compound.

Moisture curable hot melt adhesives may be used to adhere multiple fabrics together.

In another aspect, the present invention provides an adhesive body comprising a plurality of cloths and a cured product of the moisture-curable hot-melt adhesive described above for bonding the plurality of cloths together.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a moisture-curable hot-melt adhesive that exhibits high initial adhesiveness and excellent flexibility after curing. Further, according to the present invention, there is provided an adhesive body using such a moisture-curable hot-melt adhesive.

It is a schematic diagram which shows an example of the process of producing the bonded body which concerns on this embodiment.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

As used herein, "polyol" means a compound having an average of more than 1 hydroxyl group in the molecule, and "polyisocyanate" means a compound having an average of more than 1 isocyanate group in the molecule. As used herein, the term “initial adhesiveness” means adhesiveness after the adherends are pressed together via an adhesive layer formed from an adhesive and before the adhesive layer is moisture-cured.

[Moisture curing hot melt adhesive]
A moisture-curable hot-melt adhesive according to one embodiment (hereinafter sometimes simply referred to as "hot-melt adhesive") comprises a polyurethane chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and A urethane prepolymer having an isocyanate group bonded to the end of the polyurethane chain (hereinafter sometimes simply referred to as "urethane prepolymer") and a rosin compound having no hydroxyl group (hereinafter sometimes simply referred to as "rosin compound") .) and

(Rosin compound having no hydroxyl group)
The rosin compound according to the present embodiment is a compound having a rosin skeleton derived from rosin and having no hydroxyl group. The rosin skeleton may contain a rosin ester structure. The unsaturated double bond of the rosin skeleton may be hydrogenated. That is, the rosin compound may be a hydrogenated rosin ester.

The acid value of the rosin compound may be 20 mgKOH/g or less, 1 to 15 mgKOH/g, or 2 to 10 mgKOH/g, from the viewpoint of the balance between adhesiveness and flexibility after curing. The acid value can be measured according to JIS K 0070.

The softening point of the rosin compound may be 80 to 110°C, 90 to 105°C, or 90 to 100°C from the viewpoint of improving initial adhesiveness. The softening point can be measured by the ring and ball method according to JIS K 5601-2-2. Such a rosin compound is solid at room temperature and liquid at the temperature (for example, 100 to 120° C.) at which the hot melt adhesive is applied. The storage elastic modulus rises immediately, and it becomes easy to improve the initial adhesiveness.

A commercially available rosin compound can be used as it is. Commercial products of the hydroxyl group-containing rosin compound according to the present embodiment include, for example, trade names “KE-100”, “KE-311” and “KE-590” manufactured by Arakawa Chemical Industries, Ltd.

From the viewpoint of improving the initial adhesiveness, the content of the rosin compound is 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass, based on the total mass of the polyol and the rosin compound. % or more. From the viewpoint of the balance between flexibility and adhesiveness, the content of the rosin compound is 65% by mass or less, 60% by mass or less, 55% by mass or less, or 50% by mass or less based on the total mass of the polyol and the rosin compound. can be

From the viewpoint of further improving the initial adhesiveness, the rosin compound is preferably a compound compatible with polyol, more preferably a compound compatible with polybutadiene polyol and hydrogenated polybutadiene polyol.

(urethane prepolymer)
The urethane prepolymer according to this embodiment can be obtained by reacting a polyol and a polyisocyanate. The urethane prepolymer according to this embodiment is a reaction product of a polyol and a polyisocyanate, and has a polyurethane chain and an isocyanate group bonded to the end of the polyurethane chain. Urethane prepolymers having isocyanate groups can be cured by reacting with moisture. By including such a urethane prepolymer, the hot-melt adhesive according to the present embodiment can exhibit excellent adhesiveness after moisture curing.

The polyol is not particularly limited, but from the viewpoint of further improving the flexibility of the hot melt adhesive after curing, the polyol may contain at least one selected from the group consisting of polybutadiene polyol and hydrogenated polybutadiene polyol.

Polybutadiene polyol is a compound having a butadiene-derived polymer chain and hydroxyl groups at both ends of the polymer chain, and hydrogenated polybutadiene polyol is a hydrogenated polybutadiene polyol. Polybutadiene polyol and hydrogenated polybutadiene polyol may have an average of about 1.8 to 2.5 hydroxyl groups in the molecule. A polymer chain derived from polybutadiene and its hydrogenated product can act as an elastomer, and having such a polymer chain makes it possible to impart adhesiveness and flexibility to the urethane prepolymer. The polyurethane chain of the urethane prepolymer preferably contains a structural unit derived from a hydrogenated polybutadiene polyol, since it is more flexible.

Commercially available polybutadiene polyols and hydrogenated polybutadiene polyols can be used as they are. Commercially available hydrogenated polybutadiene polyols include, for example, GI-1000, GI-2000 and GI-3000 (trade names manufactured by Nippon Soda Co., Ltd.). Examples of commercially available polybutadiene polyols include G-1000, G-2000, G-3000 (all trade names manufactured by Nippon Soda Co., Ltd.), Poly bd R-15HT, Poly bd R-45HT (trade name, Idemitsu Kosan Co., Ltd.), Krasol LBH-P3000 (trade name of Clay Valley Co., Ltd.), and the like. These may be used individually by 1 type, and may be used in combination of 2 or more types.

The number average molecular weight (Mn) of polybutadiene polyol and hydrogenated polybutadiene polyol may be 500 to 100,000, 700 to 50,000, or 900 to 10,000 from the viewpoint of the balance of viscosity and adhesion. As used herein, the number average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene.

Polyols may include polyols other than polybutadiene polyols and hydrogenated polybutadiene polyols (hereinafter referred to as "other polyols"). Other polyols include, for example, polyester polyols, polyether polyols, polyacrylate polyols, polycarbonate polyols, polysiloxane polyols, polyisoprene polyols and polyolefin polyols. Other polyols may be used singly or in combination of two or more.

From the viewpoint of improving flexibility, the total content of polybutadiene polyol and hydrogenated polybutadiene polyol may be 60% by mass or more, 65% by mass or more, or 70% by mass or more based on the total mass of polyols. The total content of polybutadiene polyol and hydrogenated polybutadiene polyol is 100% by mass or less, 95% by mass or less, or 90% by mass or less, based on the total mass of polyols, from the viewpoint of the balance between flexibility and adhesiveness. It can be.

Although the polyisocyanate is not particularly limited, the polyisocyanate is preferably a diisocyanate from the viewpoint of handleability during the reaction. Examples of diisocyanates include aromatic polyisocyanates such as diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate and p-phenylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; dicyclohexylmethane diisocyanate and isophorone diisocyanate; Alicyclic polyisocyanates are mentioned. One type of polyisocyanate may be used alone, or two or more types may be used in combination. Among these, the polyisocyanate preferably contains diphenylmethane diisocyanate.

The urethane prepolymer according to this embodiment has an isocyanate group. When synthesizing such a urethane prepolymer, the mixing ratio of polyisocyanate and polyol is such that the isocyanate group (NCO) equivalent of polyisocyanate/the hydroxyl group (OH) equivalent of polyol (NCO equivalent/OH equivalent)) is 1.1 or more. is preferably adjusted to The NCO equivalents/OH equivalents may be from 1.1 to 2.2, from 1.1 to 2.1, or from 1.3 to 2.1. When the NCO equivalent/OH equivalent is 1.1 or more, an increase in viscosity of the resulting urethane prepolymer can be suppressed, and workability tends to be improved. When the NCO equivalent/OH equivalent is 2.2 or less, foaming is less likely to occur during the moisture curing reaction of the urethane prepolymer, which tends to make it easier to suppress deterioration in adhesion.

The weight average molecular weight (Mw) of the urethane prepolymer may be from 10,000 to 1,000,000, from 50,000 to 500,000, or from 100,000 to 300,000. The weight average molecular weight of the urethane prepolymer generally tends to be increased as the NCO equivalent/OH equivalent is brought closer to 1. Also, the higher the Mw of the urethane prepolymer, the higher the viscosity tends to be.

The moisture-curable hot-melt adhesive may further contain a catalyst. Catalysts include, for example, dibutyltin dilaurate, dibutyltin octate, dimethylcyclohexylamine, dimethylbenzylamine, trioctylamine, and dimorpholinodiethyl ether. The content of the catalyst is 0.001 to 0.5% by mass, 0.01 to 0.3% by mass, or 0.05 to 0.2% by mass, based on the total amount of the moisture-curable hot melt adhesive. It can be.

The moisture-curable hot-melt adhesive may further contain a thermoplastic polymer from the viewpoint of increasing rubber elasticity and imparting stronger adhesiveness. Thermoplastic polymers include, for example, polyurethanes, ethylene-based copolymers, propylene-based copolymers, vinyl chloride-based copolymers, acrylic copolymers, and styrene-conjugated diene block copolymers. The content of the thermoplastic polymer may be 10-50% by mass based on the total amount of the moisture-curable hot-melt adhesive.

The moisture-curable hot-melt adhesive may further contain a tackifier from the viewpoint of imparting stronger adhesiveness. Examples of tackifiers include rosin resins, rosin ester resins, hydrogenated rosin ester resins, terpene resins, terpene phenol resins, hydrogenated terpene resins, petroleum resins, hydrogenated petroleum resins, coumarone resins, ketone resins, styrene resins, Modified styrene resins, xylene resins, and epoxy resins are included. The content of the tackifier may be 10-50% by mass based on the total amount of the moisture-curable hot-melt adhesive. Also, the total content of the thermoplastic polymer and the tackifier may be 10-50% by mass based on the total amount of the moisture-curable hot-melt adhesive.

Moisture-curing hot-melt adhesives may optionally contain antioxidants, pigments, ultraviolet absorbers, surfactants, flame retardants, fillers, photocoloring agents, heat-preventing agents, perfumes, imaging agents, and thermal cross-linking agents. It may further contain components such as agents.

The hot melt adhesive according to the present embodiment is prepared by reacting a polyol and a polyisocyanate to obtain a polyurethane chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and an isocyanate group bonded to the end of the polyurethane chain. It can be produced by a method comprising a step of obtaining a urethane prepolymer having

The hot-melt adhesive according to this embodiment may be produced by mixing a polyol, a polyisocyanate and a rosin compound while synthesizing a urethane prepolymer. Also, the hot melt adhesive according to the present embodiment may be produced by reacting a polyol and a polyisocyanate to obtain a urethane prepolymer and then mixing it with a rosin compound.

The method for producing a hot melt adhesive according to the present embodiment may include a step of reacting a polyol with a polyisocyanate in the presence of a rosin compound to obtain a urethane prepolymer having an isocyanate group. It may include a step of reacting with polyisocyanate to obtain a urethane prepolymer having an isocyanate group, and a step of mixing the urethane prepolymer and a rosin compound.

The reaction temperature of the polyol and polyisocyanate may be, for example, 85-120°C. The temperature for mixing the urethane prepolymer and the rosin compound may be, for example, 85 to 120°C.

The viscosity at 120° C. of the moisture-curable hot melt adhesive (the moisture-curable hot melt adhesive before curing) is 0.01 Pa·s or more, 0.05 Pa·s or more, 0.1 Pa·s or more, or 1 Pa·s or more. s or more, and may be 30 Pa·s or less, 25 Pa·s or less, 20 Pa·s or less, or 15 Pa·s or less. When the viscosity at 120° C. is within the above range, workability (handleability) when applying the moisture-curable hot-melt adhesive to an adherend with a dispenser or the like is improved.

Moisture-curable hot-melt adhesives react with moisture in the air or moisture on the surface of the adherend. It can be cured by leaving it for 1 day.

From the viewpoint of flexibility, the tensile modulus of the moisture-curable hot melt adhesive after curing may be 0.01 MPa or more, 0.05 MPa or more, or 0.1 MPa or more, and 5.5 MPa or less and 5.0 MPa. or less, or 4.5 MPa or less. When used for clothing, the tensile modulus of elasticity within the above range provides excellent stretchability and reduces uncomfortable feeling when worn. In addition, in this specification, the tensile elastic modulus after curing means the value measured by the method described in Examples.

The adhesive strength (initial adhesive strength) measured before the adhesive hardens after bonding the adherend with the moisture-curable hot-melt adhesive is 0.275 N/mm (2.2 N/8 mm). 0.300 N/mm (2.4 N/8 mm) or more, or 0.325 N/mm (2.6 N/8 mm) or more. In addition, in this specification, an initial adhesive strength means the value measured by the method as described in an Example.

A moisture-curable hot-melt adhesive can be used, for example, by melting it at 60 to 130° C. and applying it to an adherend. The coating method is not particularly limited, and examples thereof include a method using a coating device such as a die coater, a roll coater, and a sprayer. A dispenser is suitable for application to narrow areas such as small parts.

The adherend is not particularly limited, and may be, for example, cloth or paper. The moisture-curable hot-melt adhesive according to this embodiment can be suitably used for adhering a plurality of cloths or papers to each other. Here, objects (adherends) to be bonded may be cloth to cloth, paper to paper, or cloth to paper.

The moisture-curable hot-melt adhesive may be used in the form of a film. A moisture-curable hot-melt adhesive film can be formed, for example, by applying a moisture-curable hot-melt adhesive onto a support film such as a PET film. The thickness of the moisture curable hot melt adhesive film may be 10 μm or more, 20 μm or more, or 30 μm or more, and may be 300 μm or less, 250 μm or less, or 200 μm or less. The thicker the moisture-curable hot-melt adhesive film, the better the adhesiveness, and the thinner the moisture-curable hot-melt adhesive film, the easier it is to ensure flexibility.

The moisture-curable hot-melt adhesive according to this embodiment can bond cloth, paper, leather, resin substrates, and the like. Objects to be bonded may be of the same material (for example, cloth and cloth) or different materials (for example, cloth and paper). Such an adhesive can be suitably used for apparel products such as clothes, supporters, bags, wallets, interiors, various covers, cases, wearable devices, and the like.

[Adhesive]
An adhesive body according to one embodiment includes a plurality of cloths and a cured product of the moisture-curable hot-melt adhesive described above for bonding the plurality of cloths together. The bonded body according to this embodiment can be used, for example, as seamless clothing.

For example, the adhesive body is formed by coating a cloth with the moisture-curable hot-melt adhesive described above to form an adhesive layer, and further placing a cloth, a wiring board having elasticity, etc. on the adhesive layer and crimping them. and leaving the obtained adhesive precursor in the air (for example, at 23° C. for 1 day) to cure the adhesive layer (moisture-curable hot-melt adhesive). and can be manufactured by a method comprising In the step of obtaining the adhesive precursor, for example, a pressure roll or the like can be used.

FIG. 1 is a schematic diagram showing an example of a process for producing a bonded body according to this embodiment. With reference to FIG. 1, the manufacturing process of a bonded body using a stretch fabric as the cloth will be described.

First, the elastic fabric 1 is placed along the jig 10 (see FIG. 1(a)). Next, the moisture-curable hot-melt adhesive according to this embodiment is applied to a predetermined portion of the stretchable fabric 1 to form an adhesive layer that will become the adhesive portion 4 (see FIG. 1(b)). The material and shape of the jig 10 are not particularly limited, and can be appropriately selected according to the purpose. Application of the adhesive may be performed, for example, using a dispenser. Next, the elastic fabric 2 is placed on the adhesive part 4, and the elastic fabric 1 and the elastic fabric 2 are attached via the adhesive part 4 while applying pressure from the elastic fabric 2 with a roll or the like. Together, an adhesive precursor is obtained (see (c) and (d) of FIG. 1). After that, the bonding part 4 is moisture-cured by curing the bonding body precursor, and the bonding body of the elastic fabric is completed.

In FIG. 1(b), the adhesive layer previously formed on the releasable base material may be transferred onto the elastic fabric 1 to form the adhesive portion 4. FIG. Alternatively, the adhesive portion 4 may be provided on the elastic fabric 2 and attached to the elastic fabric 1 . Furthermore, by changing the stretchable material 2 to a wiring board having stretchability, a bonded body of the stretchable material and the wiring board may be produced.

The bonded body according to the present embodiment maintains its elastic shape even after it is removed from the jig 10, and can recover its original shape after being stretched.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

The following ingredients were prepared to prepare a moisture-curable hot melt adhesive.
(polyol)
Hydrogenated polybutadiene polyol: Trade name "GI-3000" manufactured by Nippon Soda Co., Ltd. (number of hydroxyl groups: 2, number average molecular weight: 3000)
Rosin diol: trade name "D-6011" manufactured by Arakawa Chemical Industries, Ltd. (hydroxyl value: 117 mgKOH/g, acid value: 0.1 mgKOH/g, softening point: 95°C)
(polyisocyanate)
Diphenylmethane diisocyanate: trade name "Millionate MT" manufactured by Tosoh Corporation
(Rosin compound having no hydroxyl group)
Rosin ester: trade name "KE-311" manufactured by Arakawa Chemical Industries, Ltd. (acid value: 5, softening point: 96 ° C.)
(catalyst)
Dimorpholinodiethyl ether: trade name “UCAT-660M” manufactured by San-Apro Co., Ltd.

[Moisture curing hot melt adhesive]
(Examples 1 and 2)
Parts by mass of hydrogenated polybutadiene polyol, diphenylmethane diisocyanate, rosin ester and dimorpholinodiethyl ether shown in Table 1 were placed in a reaction vessel and mixed until uniform. Next, the mixture was allowed to react at 110° C. for 1 hour, and was further stirred at 110° C. for 1 hour under reduced pressure to defoam to prepare a hot melt adhesive containing urethane prepolymer, rosin ester and dimorpholinodiethyl ether.

(Comparative example 1)
A hot melt adhesive containing a urethane prepolymer and dimorpholinodiethyl ether was prepared in the same manner as in Examples except that the parts by mass shown in Table 1 of hydrogenated polybutadiene polyol, rosin diol, diphenylmethane diisocyanate and dimorpholinodiethyl ether were used. prepared.

(Comparative example 2)
A moisture-curable hot melt adhesive containing a urethane prepolymer and dimorpholinodiethyl ether was prepared in the same manner as in Examples except that the parts by mass shown in Table 1 of hydrogenated polybutadiene polyol, diphenylmethane diisocyanate and dimorpholinodiethyl ether were used. prepared.

Moisture-curable hot-melt adhesives were evaluated under the following conditions. Table 1 shows the results.

(exterior)
The appearance of the moisture-curable hot-melt adhesive after preparation was visually observed. When the adhesive was clear and free of turbidity, it was judged to be "uniform", and when the adhesive was turbid, it was judged to be "non-uniform".

(viscosity)
The viscosity of the moisture-curable hot-melt adhesive was measured using a rheometer (manufactured by AntonPaar, trade name "MCR-301") under the conditions of a frequency of 1 Hz, a strain angle of 2%, a gap of 0.2 mm, and 120°C. .

(adhesion strength)
A moisture-curable hot-melt adhesive was melted at 120° C., applied onto a PET film, and coated to a thickness of 80 μm using a bar coater to form an adhesive layer. The formed adhesive layer was cut into a width of 8 mm, sandwiched between elastic fabrics (spandex, Toray Oprontex Co., Ltd., Lycra (registered trademark)) of width 8 mm, and pressed against the fabric at 120°C to obtain a crimped body. . The adhesive strength of the crimped body 5 minutes after the crimping was measured using a force gauge (manufactured by Imada Co., Ltd., DS250N) to evaluate the initial adhesiveness.

(tensile modulus)
A moisture-curable hot-melt adhesive was melted at 120° C., applied onto a PET film, and coated to a thickness of 80 μm using a bar coater to form an adhesive layer. The formed adhesive layer was cured by leaving it in a constant temperature bath at 23° C. and 50% RH for 1 day to obtain a cured product of the adhesive layer. The resulting cured product of the adhesive layer was punched into a size of 5 mm×50 mm, and the PET film was peeled off to obtain a measurement sample. The tensile modulus is measured using a tensile tester (EZ-Test EZ-SX manufactured by Shimadzu Corporation) under the conditions of a measurement temperature of 25° C., a tensile speed of 100 mm/min, and a distance between chucks of 30 mm. It was obtained from the slope of the stress-strain curve at the initial stage of tension.

From the above results, it was confirmed that the moisture-curable hot-melt adhesives of Examples had high initial adhesiveness to cloth and excellent flexibility after curing.

Reference numerals 1, 2... Elastic fabric, 4... Adhering portion, 10... Jig.

Claims (4)

A urethane prepolymer having a polyurethane chain containing a polyol-derived structural unit and a polyisocyanate-derived structural unit, and an isocyanate group bonded to the end of the polyurethane chain;
a rosin compound having no hydroxyl group;
containing a moisture-curable hot-melt adhesive (however, a urethane prepolymer (d ), excluding reactive hot melt adhesives containing
The polyol contains at least one selected from the group consisting of polybutadiene polyol and hydrogenated polybutadiene polyol,
A moisture-curing hot-melt adhesive used to bond multiple fabrics together . The moisture curable hot melt adhesive of claim 1 , wherein said polyol comprises hydrogenated polybutadiene polyol. The moisture-curable hot-melt adhesive according to claim 1 or 2, wherein the content of said rosin compound is 65% by mass or less based on the total mass of said polyol and said rosin compound. a plurality of fabrics;
A cured product of the moisture-curable hot-melt adhesive according to any one of claims 1 to 3 , which bonds the plurality of cloths together;
an adhesive body.

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