ADHESIVE AND ADHESIVE TAPE

Abstract

An adhesive includes: a urethane prepolymer (A) obtained by reacting a polyol (a) with a polyisocyanate (b) under such conditions that the molar ratio of NCO/OH is 0.5-0.9 and having a molecular-weight dispersion degree [(weight-average molecular weight (Mw))/(number-average molecular weight (Mn)); hereinafter referred to also as Mw/Mn] of 4-12; a polyfunctional polyol (B), and an isocyanate curing agent (C).

Claims

1. An adhesive, comprising: a urethane prepolymer (A) which is a polymer having a molecular-weight dispersion degree of 4 to 12 obtained by reacting a hydroxyl group of a polyol (a) with an isocyanate group of a polyisocyanate (b) where a molar ratio of NCO/OH is 0.5 to 0.9; a polyfunctional polyol (B); and an isocyanate curing agent (C).

2. The adhesive according to claim 1, further comprising a fatty acid ester (D).

3. The adhesive according to claim 1, wherein the polyol (a) is one or more selected from the group consisting of a polyether polyol, a polyester polyol, a polycarbonate polyol and a polycaprolactone polyol.

4. The adhesive according to claim 1, wherein the polyisocyanate (b) is an aliphatic polyisocyanate.

5. The adhesive according to claim 1, wherein the polyol (a) comprises two or more polyols.

6. The adhesive according to claim 1, wherein the polyfunctional polyol (B) has a number average molecular weight of 1,000 to 5,000.

7. The adhesive according to claim 1, wherein the polyfunctional polyol (B) has three or more hydroxyl groups.

8. The adhesive according to claim 2, wherein the fatty acid ester (D) has a molecular weight of 200 or more.

9. The adhesive according to claim 1, further comprising one or more of a curing accelerator and a curing retarder.

10. The adhesive according to claim 1, further comprising an antioxidant.

11. The adhesive according to claim 1, wherein, in an elution curve of a weight average molecular weight obtained by measuring the adhesive by gel permeation chromatography (GPC), a high molecular weight side and a low molecular weight side partitioned by a weight average molecular weight of 10,000 as a boundary each have one peak.

12. The adhesive according to claim 1, wherein, in an elution curve of a weight average molecular weight obtained by measuring the adhesive by gel permeation chromatography (GPC), proportions of a high molecular weight component and a low molecular weight component in an entire molecular weight distribution are such that an area of the high molecular weight component is 70 to 98%, and an area of the low molecular weight component is 2 to 30% with a weight average molecular weight of 10,000 as a boundary.

13. An adhesive tape, comprising: a base material; and an adhesive layer formed of the adhesive according to claim 1.

Description

EXAMPLES

[0094] Hereinafter, the present disclosure will be specifically described with reference to examples, but the present disclosure is not limited to the examples. In the examples, “parts” refers to “parts by weight” and “%” refers to “wt%”.

[0095] Raw materials used in synthesis examples are shown below.

[0096] <Polyol (a)>

[0097] (a-1): Kuraray Polyol P-1010 (polyester polyol, number average molecular weight (Mn) 1000, two hydroxyl groups, manufactured by Kuraray Co.)

[0098] (a-2): Kuraray Polyol P-2010 (polyester polyol, number average molecular weight (Mn) 2000, two hydroxyl groups, manufactured by Kuraray Co.)

[0099] (a-3): Kuraray Polyol P-3010 (polyester polyol, number average molecular weight (Mn) 3000, two hydroxyl groups, manufactured by Kuraray Co.)

[0100] (a-4): SANNIX PP-2000 (polyether polyol, number average molecular weight (Mn) 2000, two hydroxyl groups, manufactured by Sanyo Chemical Industries, Ltd.)

[0101] (a-5): SUNNYX GP-1500 (polyether polyol, number average molecular weight (Mn) 1500, three hydroxyl groups, manufactured by Sanyo Chemical Industries, Ltd.)

[0102] (a-6): SUNNYX GP-3000 (polyether polyol, number average molecular weight (Mn) 3000, three hydroxyl groups, manufactured by Sanyo Chemical Industries, Ltd.)

[0103] (a-7): PLACCEL 220N (polycaprolactone polyol, number average molecular weight (Mn) 2000, two hydroxyl groups, manufactured by Daicel Chemical Industries, Ltd.)

[0104] (a-8): Desmophen 2020E (polycarbonate polyol, number average molecular weight (Mn) 2000, two hydroxyl groups, manufactured by Sumika Bayer Urethane Co.)

<Polyisocyanate (b)>

[0105] (b-1): Hexamethylene diisocyanate (manufactured by Tosoh Corporation)

[0106] (b-2): Takenate 500 (xylylene diisocyanate, manufactured by Mitsui Chemical Co., Ltd.)

Synthesis Example 1

[0107] In a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer and a dropping funnel, 50 parts by weight of polyester polyol (a-1), 850 parts by weight of polyether polyol (a-5), and hexamethylene diisocyanate were added such that NCO/OH was 0.5, 650 parts by weight of toluene, 0.1 parts by weight of dibutyltin dilaurate as a catalyst, and 0.25 parts by weight of tin 2-ethylhexanoate were added, and the temperature was gradually raised to 90° C. to perform a reaction for 2 hours. The reaction was terminated by cooling after confirming the disappearance of residual isocyanate groups by IR, and thereby a urethane prepolymer solution was obtained. The urethane prepolymer solution thus obtained had a nonvolatile content of 60%, weight average molecular weight (Mw) 61,000, and a molecular weight dispersion degree of 6.

Synthesis Examples 2 to 16

[0108] Each of a urethane prepolymer of Synthesis Examples 2 to 16 was obtained in the same manner as in Synthesis Example 1 except for replacing the types and amounts of the raw materials with those listed in Table 1.

[0109] <Measurement of Molecular Weight>

[0110] A weight average molecular weight (Mw), a number average molecular weight (Mn), a molecular-weight dispersion degree (Mw/Mn), the number of peaks of a high molecular weight side and a low molecular weight side partitioned by a weight average molecular weight of 10,000 as a boundary, and the ratio (%) of the high molecular weight component to the low molecular weight component were numerical values in terms of polystyrene determined by gel permeation chromatography (GPC) measurement, and the measurement conditions were as follows.

[0111] A GPC (SCL-6B, manufactured by Shimadzu Corporation) was used, the temperature of columns (KF-805L, KF-803L and KF-802 manufactured by Showa Denko KK, connected in series) was set to 40° C., tetrahydrofuran was used as an eluent, a flow rate was 0.2 ml/min, RI detection was set, a sample concentration was set to 0.02%, and polystyrene was used for standard samples when perfo g easurement.

TABLE-US-00001 TABLE 1 Synthesis Synthesis Synthesis Synthesis Synthesis Synthesis Synthesis Synthesis Mn Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Polyester polyol (a-1) 1000 50 Polyester polyol (a-2) 2000 200 300 300 Polyester polyol (a-3) 3000 300 Polyether polyol (a-4) 2000 700 Polyether polyol (a-5) 1500 600 Polyether polyol (a-6) 3000 850 700 600 400 300 200 600 Polycaprolactone 2000 600 polyol (a-7) Polycarbonate 2000 500 polyol (a-8) Hexamethylene NCO/OH 0.5 0.6 0.7 0.7 0.8 0.9 0.7 0.7 diisocyanate (b-1) ratio Xylylene NCO/OH diisocyanate (b-2) ratio Molecular weight 6 6 6 6 6 6 4 6 dispersion degree Weight average molecular 61 96 140 156 138 216 171 155 weight ( ×1000) Nonvolatile content (%) 60 60 60 60 60 60 60 60 Synthesis Synthesis Synthesis Synthesis Synthesis Synthesis Synthesis Synthesis Mn Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Polyester polyol (a-1) 1000 300 300 300 300 300 Polyester polyol (a-2) 2000 300 300 300 Polyester polyol (a-3) 3000 Polyether polyol (a-4) 2000 Polyether polyol (a-5) 1500 600 Polyether polyol (a-6) 3000 600 600 600 600 600 600 600 Polycaprolactone 2000 polyol (a-7) Polycarbonate 2000 polyol (a-8) Hexamethylene NCO/OH 0.7 0.7 0.4 0.95 0.7 0.7 0.7 diisocyanate (b-1) ratio Xylylene NCO/OH 0.7 diisocyanate (b-2) ratio Molecular weight 8 10 12 6 6 1.5 3 15 dispersion degree Weight average molecular 219 186 251 49 382 84 132 366 weight (×1000) Nonvolatile content (%) 60 60 60 60 60 60 60 60 *Units of the amounts mixed in are parts by weight.

[0112] In examples, the following raw materials were used.

<Polyol (B)>

[0113] (B-1): Adeka polyether G700 (polyether polyol, number average molecular weight (Mn) 700, three functional groups, manufactured by ADEKA Corporation)

[0114] (B-2): Adeka polyether G1500 (polyether polyol, number average molecular weight (Mn) 1500, three functional groups, manufactured by ADEKA Corporation)

[0115] (B-3): Adeka polyether G3000B (polyether polyol, number average molecular weight (Mn) 3000, three functional groups, manufactured by ADEKA Corporation)

[0116] (B-4): Adeka polyether AM502 (polyether polyol, number average molecular weight (Mn) 5000, three functional groups, manufactured by ADEKA Corporation)

[0117] (B-5): Adeka polyether AM702 (polyether polyol, number average molecular weight (Mn) 7000, three functional groups, manufactured by ADEKA Corporation)

[0118] <Isocyanate Curing Agent (C)>

[0119] (C-1): Coronate HL (trimethylolpropane adducts of hexamethylene diisocyanate, a nonvolatile content of 75%, manufactured by Tosoh Corporation)

[0120] (C-2): Sumidur N-3300 (isocyanurate of hexamethylene diisocyanate, a nonvolatile content of 100%, manufactured by Sumika Bayer Urethane Co.)

[0121] <Fatty acid ester (D)>

[0122] (D-1): Isopropyl palmitate

[0123] (D-2): Isopropyl myristate

[0124] (D-3): Methyl oleate

Example 1

[0125] 100 parts by weight of the urethane prepolymer solution of Synthesis Example 1, 2 parts by weight of the multifunctional polyol (B-1), 8.0 parts by weight of the isocyanate curing agent (C-1), 20.0 parts by weight of the fatty acid ester (D-1), 0.3 parts by weight of a polymeric phenolic antioxidant IRGANOX L 135 (manufactured by BASF Co.), 0.3 parts by weight of a benzotriazole-based ultraviolet absorber TINUVIN 571 (manufactured by BASF Co.), 0.3 parts by weight of a hindered amine light stabilizer TINUVIN 765 (manufactured by BASF Co.), and ethyl acetate as a solvent were mixed in appropriate amounts and stirred with a Disper to obtain an adhesive. The adhesive thus obtained was applied to polyethylene terephthalate (Lumirror T-60, manufactured by Toray Industries, Inc.) having a thickness of 50 μm as a base material so as to have a thickness after drying of 20 μm, followed by drying at 100° C. for 2 minutes. A release liner (silicone release layer) having a thickness of 38 μm was laminated thereon. Subsequently, the laminate was left at room temperature for a week to obtain an adhesive tape.

Examples 2 to 11 and Comparative Examples 1 to 7

[0126] Each of an adhesive tape of Synthesis Examples 2 to 13 and Comparative Examples 1 to 5 was obtained in the same manner as in Example 1 except for replacing the types and amounts of the raw materials with those listed in Table 1.

Comparative Example 8

[0127] 80 parts by weight of PREMINOL 53011 (polyether polyol, number average molecular weight (Mn) 10,000, three functional groups, manufactured by Asahi Glass Co., Ltd.), 20 parts by weight of SANNIX GP-1500, 25 parts by weight of Sumidur N-3300, 0.04 parts by weight of Narsem II iron (manufactured by Nippon Chemical Industrial Co., Ltd.) as a catalyst and 266 parts by weight of ethyl acetate (diluting solvent) were mixed and stirred with a Disper to obtain an adhesive. The obtained adhesive was applied as a base material to polyethylene terephthalate having a thickness of 50 μm such that the thickness of the adhesive layer after drying was 20 μm, and dried under conditions of a temperature of 130° C. for 2 minutes, and a release liner having a thickness of 38 μm was bonded to the adhesive layer afterwards. Subsequently, the layers were left at room temperature for 1 week to obtain an adhesive tape.

[0128] The adhesive tape obtained was evaluated according to the following items.

[0129] <Curved Surface Fitness>

[0130] The obtained adhesive tape was prepared to have a size of 25 mm in width and 100 mm in length, and used as a measurement sample. Subsequently, the release liner was peeled off in an atmosphere of 23° C. and 50% RH, and the exposed adhesive layer was laminated along the circumference of a polypropylene cylinder (diameter of 15 mm), such that an adhesive tape sample with the exposed adhesive layer, which had a width of 10 mm corresponding to the length of a half circumference of the circumference was bonded along the circumference of a polypropylene cylinder (diameter: 15 mm), and the lifting state of the measurement sample was observed after 3 days. The evaluation criteria were as follows.

[0131] A: There was no lifting, and a measurement sample was in close contact. Good

[0132] B: There was lifting of less than 1 mm, and an end portion was slightly lifted. Practical use possible.

[0133] C: There was lifting of more than 1 mm. Practical use not possible.

[0134] <Adhesive Force>

[0135] The obtained adhesive tape was prepared to have a size of 25 mm in width and 100 mm in length and used as a measurement sample. Subsequently, the release liner was peeled off in an atmosphere of 23° C. and 50% RH, the exposed adhesive layer was adhered to a glass plate and pressured with a 2 kg-roll, and then left to stand for 24 hours. Thereafter, the adhesive strength was measured with a tensile tester under conditions of a peel rate of 300 mm/min and a peel angle of 180° in accordance with JISZ 0237. The evaluation criteria were as follows.

[0136] A: Less than 50 mN/25 mm. Good.

[0137] B: 50 mN/25 mm or more, less than 200 mN/25 mm. Practical use possible.

[0138] C: 200 mN/25 mm or more. Practical use not possible.

[0139] <Removability>

[0140] The obtained adhesive tape was prepared to have a width of 25 mm and a length of 100 mm and used as a measurement sample. Subsequently, the release liner was peeled off in an atmosphere of 23° C. and 50% RH, the exposed adhesive layer was adhered to a glass plate and pressured with a 2 kg-roll, and then left to stand in an environment of 150° C. for 24 hours. Thereafter, it was air-cooled in an atmosphere at 23° C. and 50% RH for 30 minutes, and the adhesive strength was measured under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180° using a tensile tester according to JIS Z 0237. The evaluation criteria were as follows.

[0141] A: Less than 100 mN/25 mm. Good.

[0142] B: 100 mN/25 mm or more and less than 400 mN/25 mm. Practical use possible.

[0143] C: 400 mN/25 mm or more. Practical use not possible.

[0144] <Wettability>

[0145] The obtained adhesive tape was prepared to have a size of 50 mm in width and 100 mm in length and used as a measurement sample. Subsequently, after standing in an atmosphere of 23° C. and 50% RH for 30 minutes, the release liner was peeled off from the measurement sample, the central portion of the exposed adhesive layer was brought into contact with a glass plate while holding both ends of the adhesive tape with the hands, and then the hands were released therefrom. The adhesion of the adhesive tape to the glass was evaluated by measuring the time until an entire adhesive layer was adhered to the glass plate due to the weight of the adhesive tape. The shorter the time until the entire adhesive layer is adhered to the glass, the better the affinity for the glass is, and thus it is easy to protect the glass in the manufacturing process using the glass material. The evaluation criteria were as follows.

[0146] A: Less than 3 seconds until close contact. Good.

[0147] B: 3 seconds or more and less than 5 seconds until close contact. Practical use possible.

[0148] C: 5 seconds or more until close contact. Practical use not possible.

[0149] <Cuttability>

[0150] When the surface of the adhesive layer of the obtained adhesive tape was scratched with a blade of a cutter knife and rubbed with a finger, cuttability was evaluated by visually judging whether or not aggregates peeling off from the adhesive layer were generated. Visual inspection was performed under fluorescent light. When the cohesive force of the adhesive layer was excellent, aggregates were not generated. Evaluation was carried out according to the following criteria. Further, whether workability is excellent or poor can be judged by cuttability.

[0151] A: Aggregates were generated. Good.

[0152] C: No aggregates were generated. Practical use not possible.

TABLE-US-00002 TABLE 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Synthesis Example 1 100 Synthesis Example 2 100 Synthesis Example 3 100 Synthesis Example 4 100 Synthesis Example 5 100 Synthesis Example 6 100 Synthesis Example 7 100 Synthesis Example 8 100 Synthesis Example 9 100 Synthesis Example 10 100 Synthesis Example 11 Synthesis Example 12 Synthesis Example 13 Synthesis Example 14 Synthesis Example 15 Synthesis Example 16 Polyol (B-1) Polyol (B-2) 2 4 8 2 Polyol (B-3) 2 4 8 2 Polyol (B-4) 2 4 8 Polyol (B-5) PREMINOL S3011 SANNIX GP-1500 Isocyanate curing 15 15 15 15 15 15 15 agent (C-1) Isocyanate curing 15 15 15 agent (C-2) IRGANOX L135 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 TINUVIN 571 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 TINUVIN 765 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Fatty acid ester (D-1) 25.0 30.0 35.0 20.0 Fatty acid ester (D-2) 25.0 30.0 35.0 Fatty acid ester (D-3) 25.0 30.0 35.0 Number of peaks 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/2 High-molecular weight side/ Low-molecular weight side Ratio of high- 98/2  96/4  93/7  98/2  96/4  93/7  98/2  96/4  93/7  96/4  molecular component/ Low-molecular component Results of physical properties Curved surface B A A B A A B A A A fitness Adhesive force A A A A A A A A A B Removability A A A A A A A A A B Wettability A A B A A B A A B B Cuttability A A A A A A A A A A *Units of the amounts mixed in are parts by weight.

TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Comparative Comparative Comparative Example 11 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 12 Example 13 Synthesis Example 1 100 Synthesis Example 2 100 Synthesis Example 3 Synthesis Example 4 Synthesis Example 5 Synthesis Example 6 Synthesis Example 7 Synthesis Example 8 Synthesis Example 9 Synthesis Example 10 Synthesis 100 Example 11 Synthesis 100 Example 12 Synthesis 100 Example 13 Synthesis 100 Example 14 Synthesis 100 Example 15 Synthesis 100 Example 16 Polyol (B-1) 4 Polyol (B-2) 2 Polyol (B-3) 4 4 4 4 4 Polyol (B-4) 2 Polyol (B-5) 4 PREMINOL S3011 80 SANNIX GP-1500 20 Isocyanate 15 15 15 15 15 15 15 curing agent (C-1) Isocyanate 15 25 curing agent (C-2) IRGANOX L135 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 TINUVIN 571 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 TINUVIN 765 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Fatty acid 25.0 25.0 ester (D-1) Fatty acid 20.0 25.0 25.0 ester (D-2) Fatty acid 20.0 25.0 25.0 ester (D-3) Number of peaks 1/2 1/1 1/1 1/1 1/1 1/1 0/2 1/1 1/1 High-molecular weight side/ Low-molecular weight side Ratio of high- 96/4  96/4  96/4  96/4  96/4  96/4   0/100 96/4  96/4  molecular component/ Low-molecular component Results of physical properties Curved surface A C C C C C C B B fitness Adhesive force B B A A A A B A A Removability B B A A A A B A A Wettability B B B B B C B B B Cuttability A C A C C C A B B