Moisture-Curable Hot-Melt Adhesive Agent

Abstract

Objective:

To provide a moisture-curable hot-melt adhesive agent having excellent balance of initial adhesive strength, adhesive strength after curing and heat resistance and the like, and a layered product bonded with the moisture-curable hot-melt adhesive agent.

Means for solving the problem: A moisture-curable hot-melt adhesive agent comprising an urethane prepolymer having an isocyanate group at the end (A), a styrene based block copolymer (B), and a tackifying resin (C), wherein the styrene based block copolymer (B) comprises a styrene based block copolymer having 10 to 35% by weight of a styrene content (B1) and a styrene based block copolymer having 40 to 70% by weight of a styrene content (B2).

Claims

1. A moisture-curable hot-melt adhesive agent comprising an urethane prepolymer having an isocyanate group at the end (A), a styrene based block copolymer (B), and a tackifying resin (C), wherein the styrene based block copolymer (B) comprises a styrene based block copolymer having 10 to 35% by weight of a styrene content (B1) and a styrene based block copolymer having 40 to 70% by weight of a styrene content (B2).

2. The moisture-curable hot-melt adhesive agent according to claim 1, wherein (B1) is a styrene-isoprene based block copolymer, and (B2) is a styrene-isoprene based block copolymer.

3. The moisture-curable hot-melt adhesive agent according to claim 1, wherein the moisture-curable hot-melt adhesive agent comprises 25 to 64 parts by weight of (A), 10 to 40 parts by weight of (B1) and 10 to 40 parts by weight of (B2), based on 100 parts by weight in total of (A) and (B).

4. The moisture-curable hot-melt adhesive agent according to claim 1, wherein the moisture-curable hot-melt adhesive agent comprises 60 to 110 parts by weight of the tackifying resin (C), based on 100 parts by weight in total of (A) and (B).

5. The moisture-curable hot-melt adhesive agent according to claim 1, wherein the styrene based block copolymer (B2) is a triblock copolymer.

6. A layered product comprising a substrate, an adhesive agent layer formed on a surface of the substrate and an adherend adhered to a surface of the adhesive agent layer, wherein the adhesive layer consists of the moisture-curable hot-melt adhesive agent according to claim 1.

Description

EXAMPLES

[0103] The present invention will hereinafter be described by using Examples and Comparative Examples. These Examples are merely for illustrative purposes and are not meant to limit the present invention in any way.

[0104] Components for producing the hot melt adhesive are shown below.

(A) Materials for Constituting an Urethane Prepolymer Having Terminal Isocyanate Groups

[0105] Polyol Component

(A1) polyester polyol (HS2F-231AS (trade name) manufactured by Hokoku Corporation, melting point: 30 C., hydroxyl value: 56 (mgKOH/g))
(A2) polyester polyol (HS2H-350S (trade name) manufactured by Hokoku Corporation, melting point: 5 C., hydroxyl value: 32 (mgKOH/g))
(A3) polyester polyol (HS2E-581A (trade name) manufactured by Hokoku Corporation, melting point: 5 C., hydroxyl value: 21 (mgKOH/g))
(A4) polypropylene glycol (High-Flex D-2000 (trade name) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., hydroxyl value: 56 (mgKOH/g)

Isocyanate Component

[0106] (A5) 4,4-diphenylmethane diisocyanate (Millionate MT (trade name) manufactured by Tosoh Corporation)

(B) Styrene Based Block Copolymer

[0107] (B1-1) styrene-isoprene block copolymer (JSR5403 (trade name) manufactured by JSR Corporation, styrene content: 15 wt %, diblock content: 40 wt %, MFR 20 g/10 min.: 200 C.
(B1-2) styrene-isoprene block copolymer (Quintac 3433N (trade name) manufactured by Zeon Corporation, styrene content: 16 wt %, diblock content: 56 wt %, MFR 12 g/10 min.: 200 C.
(B1-3) styrene-isoprene block copolymer (Quintac 3270 (trade name) manufactured by Zeon Corporation, styrene content: 24 wt %, diblock content: 67 wt %, MFR 20 g/10 min.: 200 C.
(B1-4) styrene-isoprene block copolymer (Quintac SL-165 (trade name) manufactured by Zeon Corporation, styrene content: 30 wt %, diblock content: 60 wt %, MFR 16 g/10 min.: 200 C.
(B1-5) styrene-butadiene block copolymer (Asaprene T432 (trade name) manufactured by Asahi Kasei Chemicals Corporation, styrene content: 30 wt %, diblock content: 25 wt %, MFR 0.2 g/10 min.: 200 C.)

[0108] (B2-1) styrene-isoprene block copolymer (D1162 (trade name) manufactured by Clayton Corporation, styrene content: 43 wt %, diblock content: 0 wt % (triblock copolymer), MFR 45 g/10 min.: 200 C.)

(B2-2) styrene-butadiene block copolymer (Asaprene T439 (trade name) manufactured by Asahi Kasei Chemicals Corporation, styrene content: 45 wt %, diblock content: 62 wt %, MFR not publicly disclosed)
(B2-3) styrene-butadiene block copolymer (TR2250 (trade name) manufactured by JSR Corporation, styrene content: 52 wt %, diblock content: 0 wt % (triblock copolymer), MFR 4.0 g/10 min.: 200 C.)
(B2-4) styrene-butadiene-butylene block copolymer (Tuftec P2000 (trade name) manufactured by Asahi Kasei Chemicals Corporation, styrene content: 67 wt %, diblock content: 0 wt % (triblock copolymer), MFR 3.0 g/10 min.: 190 C.)

(C) Tackifying Resin

[0109] (C1) Unhydrogenated C5 resin (WINGTACK 86 (trade name) manufactured by Cray Valley LLC., softening point: 87 C.)
(C2) Fully hydrogenated DCPD resin (T-REZ HA103 (trade name) manufactured by Tonen General Sekiyu K.K, softening point: 103 C.)
(C3) Partially hydrogenated C9 resin (Arkon M-100 (trade name) manufactured by Arakawa Chemical Industries, Ltd.)
(C4) Fully hydrogenated C9 resin (Arkon P-125 (trade name) manufactured by Arakawa Chemical Industries, Ltd.)
(C5) Urethane modified rosin (the production method is described below (Table 1))
(C6) Urethane modified rosin (the production method is described below (Table 1)
(C7) Urethane modified rosin (the production method is described below (Table 1)
(C8) Urethane modified rosin (the production method is described below (Table 1)

[0110] (D) Plasticizer

(D1) Naphthene oil (SUNPURE N90 (trade name) manufactured by JAPAN SUN OIL COMPANY, LTD.)
(D2) Paraffin oil (DUPHNE OIL KP68 (trade name) manufactured by Idemitsu Kosan Co., Ltd.
(D3) Rice oil (Rice Salad Oil (trade name) manufactured by Boso Yushi Co., Ltd.)

(E) Other Additives

[0111] (E1) Antioxidant (Adekastab AO-60 (trade name) manufactured by ADEKA CORPORATION)

[0112] Production of Moisture-Curable Hot-Melt Adhesive Agent

[0113] A method for producing urethane modified rosin will be described.

[0114] First, a rosin ester component (F) was charged in a reaction container, and the rosin ester component was melted in an oven at 130 C. Thereafter, it was stirred under reduced pressure for one hour while heating the reaction container in an oil bath at 130 C. to remove its moisture. Subsequently, an isocyanate component (A5) or (G1) was charged in a NCO/OH ratio of 1.05, and the mixture was stirred under reduced pressure for one hour at 130 C. to obtain urethane modified rosin (C).

[0115] The urethane modified rosin was subjected to infrared spectroscopic analysis (FT-IR analysis). It was confirmed that the absorption at 2300 cm.sup.1 due to the isocyanate group, and the absorption at 3400 cm.sup.1 due to the hydroxyl group almost disappeared.

[0116] Combinations of the rosin ester component and the isocyanate component are as shown in Table 1.

TABLE-US-00001 TABLE 1 Urethane Modified Rosin Combination of Components (C5) (F1) (A5) (C6) (F1) (G1) (C7) (F2) (G1) (C8) (F3) (G1)

(F) Rosin Ester as a Constituent of Urethane Modified Rosin

[0117] (F1) Rosin ester resin having hydroxyl groups (SYLVALITE RE 85 GB (trade name) manufactured by Arizona Chemical Company, LLC., softening point: 85 C., hydroxyl value: 25 (mgKOH/g))
(F2) Rosin ester resin having hydroxyl groups (SYLVALITE RE 105L (trade name) manufactured by Arizona Chemical Company, LLC., softening point: 105 C., hydroxyl value: 10 (mgKOH/g))
(F3) Rosin ester resin having hydroxyl groups (Super Ester T125 (trade name) manufactured by Arakawa Chemical Industries, Ltd., softening point: 125 C., hydroxyl value: 7 (mgKOH/g))

(G) Isocyanate as a Constituent of Urethane Modified Rosin

[0118] (G1) p-Toluenesulphonyl Isocyanate

Example 1

[0119] Components (A) to (E) were mixed to produce a moisture-curable hot-melt adhesive agent.

[0120] Specifically, components (B1-4), (B2-1), (C3), (C4), (C5), (D1) and (E1) were melt-mixed in the composition (part by weight) shown in Table 2 by a universal agitator to prepare a melted composition.

[0121] Then, polyester polyols (A3) and the above melted compositions were mixed in the composition shown in Table 2 (part by weight). The mixture was put in a reaction container. After heating the mixture at 130 C., the mixture was stirred under reduced pressure for one hour at the same temperature. After confirming that moisture has been removed and that the mixture has been sufficiently kneaded, 4,4-diphenylmethane diisocyanate (A5) was added thereto, and the mixture was stirred under reduced pressure for one hour at the same temperature to obtain a moisture-curable hot-melt adhesive agent.

Examples 2-7, Comparative Examples 1-4

[0122] In the compositions shown in Tables 2 and 4, components (A) to (E) were prepared in the same process as in Example 1 to produce moisture-curable hot-melt adhesive agents.

[0123] With regard to the thus obtained moisture-curable hot-melt adhesive agents, the melt viscosity, heat resistance (creeping test), initial adhesive strength (tack), and adhesive strength after curing (durability test) were measured. The results are shown in Tables 3 and 5.

TABLE-US-00002 TABLE 2 Raw material Raw material Raw material classification 1 classification 2 classification 3 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Urethane Polyol (A1) 36.6 prepolymer (A2) 11.0 (A) (A3) 57.5 53.3 54.6 19.2 60.7 58.1 (A4) 7.69 Isocyanate (A5) 5.7 6.1 5.4 3.8 6.0 8.5 5.7 Styrene Low St (B1-1) 20.0 based block content (B1) (B1-2) 16.8 24.4 copolymer (B1-3) 34.6 (B) (B1-4) 14.7 29.8 (B1-5) 11.1 High St (B2-1) 22.1 23.8 20.0 34.6 content (B2) (B2-2) 22.2 (B2-3) 19.5 (B2-4) 6.4 Tackifying resin (C) (C1) 32.0 44.4 34.9 38.3 (C2) 14.5 (C3) 10.5 (C4) 23.2 25.7 (C5) 56.1 39.4 (C6) 41.4 36.4 (C7) 41.5 23.0 63.3 44.1 (C8) 12.5 Plasticizer (D) (D1) 24.2 28.0 22.2 35.9 31.9 (D2) 14.9 (D3) 28.8 Additive (E) (E1) 0.4 0.4 0.4 0.4 0.4 0.4 0.4 NCO/OH (Ratio of functional groups) 2.1 2.5 2.1 2.1 2.1 1.6 2.1 Total 210.95 191.09 200.00 163.85 222.22 243.90 212.77
The unit of amount shown in Table 2 is part by weight.

TABLE-US-00003 TABLE 3 Measurement Item Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Viscosity (mPas) 33500 50300 70600 53500 33250 77000 83000 Creep (min) 9.6 6.8 7.6 3.3 6.3 4.8 6.5 Evaluation of heat resistance Tack (g/cm.sup.2) 5 C. 3100 2560 2100 3461 1720 1920 2220 23 C. 3650 4100 2400 4100 2710 2530 2630 35 C. 4400 3000 4100 4710 3380 2980 3140 Evaluation of 5 C. Initial adhesive 23 C. strength 35 C. Evaluation of adhesive strength after curing

TABLE-US-00004 TABLE 4 Raw material Raw material Raw material Comp. Comp. Comp. Comp. classification 1 classification 2 classification 3 Example 1 Example 2 Example 3 Example 4 Urethane Polyol (A1) prepolymer (A2) (A) (A3) 56.9 47.5 54.6 56.9 (A4) Isocyanate (A5) 5.6 2.5 5.4 5.6 Styrene Low St (B1-1) based block content (B1) (B1-2) 20.0 copolymer (B1-3) 37.5 20.0 (B) (B1-4) (B1-5) High St (B2-1) 50.0 20.8 content (B2) (B2-2) (B2-3) 16.7 (B2-4) Tackifying resin (C) (C1) 41.7 40.0 41.7 (C2) 35.0 (C3) (C4) (C5) (C6) 54.6 41.0 (C7) 38.9 41.5 (C8) Plasticizer (D) (D1) 29.2 40.0 20.0 29.2 (D2) (D3) 28.8 Additive (E) (E1) 0.4 0.4 0.4 0.4 NCO/OH (Ratio of functional groups) 2.1 1.6 2.1 2.1 Total 208.33 225.00 200.00 208.33
The unit of amount shown in Table 4 is part by weight.

TABLE-US-00005 TABLE 5 Comp. Comp. Comp. Comp. Measurement Item Example 1 Example 2 Example 3 Example 4 Viscosity (mPas) 41750 11600 64167 50920 Creep (min) 2.3 5.1 1.9 2.6 Evaluation of heat X X X resistance Tack (g/cm.sup.2) 5 C. 3003 1425 3860 422 23 C. 3900 2089 4620 987 35 C. 3330 4081 3462 1808 Evaluation of 5 C. X X initial 23 C. X adhesive 35 C. strength Evaluation of adhesive X strength after curing (durability)

[0124] The measurement and evaluation methods will be described.

Melt Viscosity

[0125] The viscosity at 130 C. of each moisture-curable hot-melt adhesive agent was measured in accordance with the method B defined in JAI 7-1991. For the measurement, a Brookfield viscometer and a No. 27 rotor were used.

Heat Resistance (Creep)

[0126] A particle board (10.0 cm10. cm2 cm), which was allowed to stand in a thermostat at 25 C. for 12 hours or more, was used as a test material. The particle board was coated with each of the hot melt adhesives of Examples and Comparative Examples at 130 C. by a roll coater. The thickness of the coated adhesive agent was 7010 m.

[0127] A melamine board (13.0 cm2.5 cm) and the particle board were laminated together by the coated adhesive. Specifically, the melamine board was set up so that it stuck 2 cm from the particle board, and both of the boards were laminated together by a roll press machine to serve as a creep test sample.

[0128] This sample was fixed at an upper part of the thermostat at 80 C. The sample was fixed so that the melamine board sticking out 2 cm was fixed on the lower side. After preheating the sample for one minute, a 245-g weight was hung on the tab portion which stuck out 2 cm (melamine board), and the time until the weight fell off was measured to evaluate creep properties.

[0129] Since the purpose of the present test is evaluation of the heat resistance (creep properties) before the reaction, a series of operations from coating until start of measurement was performed within 3 minutes.

[0130] Creep was evaluated by the time from the start of the measurement until an evaluation piece of the melamine board fell off. The evaluation criteria are as follows.

: 7.0 minutes or more
: 5.0 minutes or more and less than 7.0 minutes
: 3.0 minutes or more and less than 5.0 minutes [0131] X: less than 3.0 minutes

Initial Adhesive Strength (Tack)

[0132] On a 50 m-thick PET film, each of hot-melt adhesive agents of Examples and Comparative Examples was coated to a thickness of 50 m, and the PET film after coating was set in a Peltier thermal control unit.

[0133] Tack measurement was conducted using a tack tester in which a 5 mm-diameter plunger was set. The tack measurement was conducted at a pressing force during tack measurement of 1.5 kg/cm.sup.2, a pressing time of one second, and a speed of 10 mm/sec when moving a plunger up and down.

[0134] The measurement was conducted under three temperature conditions. The present test is intended to evaluate the initial adhesive strength before the reaction, a series of operations from coating until start of measurement was performed within 3 minutes.

[0135] Evaluation criteria for the tack are as follows:

: 3500 g/cm.sup.2 or more
: 2500 g/cm.sup.2 or more and less than 3500 g/cm.sup.2
: 1500 g/cm.sup.2 or more and less than 2500 g/cm.sup.2 or less
X: less than 1500 g/cm.sup.2
Adhesive Strength after Curing (Durability)

[0136] A particle board (10.0 cm10. cm2 cm), which was allowed to stand in a thermostat at 25 C. for 12 hours or more, was used as a test material. The particle board was coated with each of the hot melt adhesives of Examples and Comparative Examples at 130 C. by a roll coater. The thickness of the coated adhesive agent was 7010 m.

[0137] A melamine board (13.0 cm2.5 cm) and the particle board were laminated together through the coated adhesive agent to serve as a sample. After curing the sample at room temperature for one week or more, it was allowed to stand in a thermostat at 60 C. After left standing for 24 hours, the sample was taken out, and whether or not lifting or peeling occurs on the melamine board and the particle board was confirmed by visual inspection.

[0138] Evaluation criteria for the durability are as follows:

: No lifting or peeling was observed.
X: Lifting or peeling was observed.

[0139] As shown in Table 3, the moisture-curable hot-melt adhesive agents of the Examples are favorable in all the heat resistance (creep), initial adhesive strength (tack), and adhesive strength after curing (durability). In particular, a moisture-curable hot-melt adhesive agent of Example 1 has high creep performance that serves as an indication of heat resistance, and favorable initial adhesive strength (tack) at a wide temperature range of 5 to 35 C.

[0140] As shown in Table 5, moisture-curable hot-melt adhesive agents of the Comparative Examples have a poor balance of the creep, tack and durability, so that any of the evaluation items are indicated by X.

[0141] Therefore, it has been demonstrated that by including all the components (A), (B1), (B2) and (C), the moisture-curable hot-melt adhesive agent becomes excellent in the heat resistance, initial adhesive strength, and adhesive strength after curing.

INDUSTRIAL APPLICABILITY

[0142] The present invention provides a moisture-curable hot-melt adhesive agent. The moisture-curable hot-melt adhesive agent is useful in producing layered products in various usages such as exterior and interior materials of building materials, flooring, lamination of a decorative sheet on a substrate, and profile wrapping.