THIOL GROUP-CONTAINING POLYETHER POLYMER, EPOXY RESIN-CONTAINING COMPOSITION, AND CURING AGENT FOR EPOXY RESIN

Abstract

A thiol group-containing polyether polymer is provided which has a lower viscosity than that of an epoxy adhesive in which a conventional polymercaptan curing agent is used and which is excellent in workability and can maintain the low viscosity of an epoxy adhesive even when the amount of the additive is increased. The thiol group-containing polyether polymer includes a polyether moiety represented by general formula (1) below and a structural unit represented by general formula (2) below in a main chain; and a structural unit represented by general formula (3) below at a terminal, where R.sup.1, R.sup.2, n and m of formula (1); x and I of formula (2); and I of formula (3) are as defined.

##STR00001##

Claims

1. A thiol group-containing polyether polymer, comprising: a polyether moiety represented by general formula (1) below and a structural unit represented by general formula (2) below in a main chain; and a structural unit represented by general formula (3) below at a terminal, wherein a ratio [SH]/[S.sub.x] of a peak area corresponding to a structural unit of-SH to a peak area corresponding to a structural unit of S.sub.x in structural analysis by 13CNMR measurement is 7.0 or more: ##STR00010## wherein R.sup.1 is a residue obtained by removing a hydrogen atom from a polyamine or polyhydric alcohol having 10 or less carbon atoms, R.sup.2 is an alkylene group having 2 to 6 carbon atoms, n is an integer of 1 to 200, and m is an integer of 2 to 8, ##STR00011## wherein S.sub.x represents one or two or more consecutive sulfur atoms, x is an integer of 1 to 5, and l is an integer of 0 to 10, ##STR00012## wherein l is an integer of 0 to 10.

2. The thiol group-containing polyether polymer according to claim 1, comprising 10% by mass to 18% by mass of a thiol group.

3. The thiol group-containing polyether polymer according to claim 1, having a viscosity at 25 C. of 0.1 Pa.Math.s to 10 Pa.Math.s.

4. The thiol group-containing polyether polymer according to claim 1, having a viscosity at 5 C. of 1 Pa.Math.s to 70 Pa.Math.s.

5. An epoxy resin-containing composition, comprising: 100 to 600 parts by mass of an epoxy resin relative to 100 parts by mass of the thiol-containing polyether polymer according to claim 1.

6. The epoxy resin-containing composition according to claim 5, comprising 1 to 60 parts by mass of an amine relative to 100 parts by mass of the epoxy resin.

7. The epoxy resin-containing composition according to claim 5, having a Shore D hardness according to JIS K7215 of 70 or more and a lap shear strength according to JIS K6850 of 12 MPa or more after 24 hours from a starting point in time of curing of the epoxy resin-containing composition.

8. A curing agent for an epoxy resin, comprising the thiol group-containing polyether polymer according to claim 1.

Description

EXAMPLES

[0070] The present invention will be specifically described by means of Example and Comparative Examples below. In the following Example, a general reagent purchased from a reagent manufacturer was used as a raw material unless otherwise specified. The following apparatus and method were used for the analysis.

[00001]$\begin{array}{cc}\left[\mathrm{Measurement}\mathrm{method}\right]& \\ \left[-\mathrm{SH}\right]/\left[-S_x-\right]& \left(1\right)\end{array}$

[0071] Structural analysis was performed by .sup.13CNMR measurement using a nuclear magnetic resonance apparatus (ECZ-600R manufactured by JEOL RESONANCE), and the ratio of the peak area by the structural unit of [SH] to the peak area by the structural unit of [S.sub.x] was calculated.

(2) Viscosity

[0072] The viscosities of a sample at 25 C. and 5 C. were measured using a viscometer (U-EII manufactured by Toki Sangyo Co., Ltd.).

(3) Content of Thiol Group

[0073] A weighed sample was dissolved in a mixed solution of toluene and pyridine, an aqueous potassium iodide solution was added thereto, and then the resulting solution was titrated with an iodine standard solution to measure the content of thiol groups.

(4) Content of Chlorine

[0074] The content of chlorine contained in the thiol group-containing polyether polymer was measured using an elemental analyzer (NSX-2100 manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

(5) Pot Life

[0075] The pot life of the epoxy resin-containing composition was measured according to Determination of the pot life of multi-component adhesives (Method 1) of JIS K6870. In the present invention, 10 g of a bisphenol A-type epoxy resin (jER 828 manufactured by Mitsubishi Chemical Group Corporation, epoxy equivalent: 184 to 194) as an epoxy resin, 8.0 g of each thiol group-containing polyether polymer of Example and Comparative Examples, and 1 g of an amine compound (EHC-30 manufactured by ADEKA CORPORATION) were mixed under conditions of 23 C. and 50% RH, a toothpick was put into the epoxy resin-containing composition, a mixture, and the point at which the toothpick did not move even when touched by a finger was measured as the pot life. The pot life was measured from the starting point in time of curing, and the state of the toothpick was checked every 15 seconds to determine the pot life in minutes.

(6) Hardness

[0076] The hardness of the epoxy resin-containing composition was measured by a method specified in JIS K7215. Specifically, the epoxy resin-containing composition was poured into containers having an inner diameter of 31 mm and a depth of 8 mm in a room at a temperature of 23 C. and a humidity of 50% RH, and after 24 hours from the starting point in time of curing of the epoxy resin-containing composition, a sample for measurement having a diameter of 31a thickness of 8 mm was obtained. The hardness of the flat surface of the sample was measured using a type D durometer.

[0077] The measurement was performed three times, and the average value was taken as the numerical value of the hardness.

(7) Lap Shear Strength

[0078] The lap shear strength of the epoxy resin-containing composition was measured according to the method specified in JIS K6850. The specific measurement method is shown below. Adherend: The surface of a 100 mm25 mm3 mm soft steel plate (sandblasted) was degreased using acetone and then methyl ethyl ketone to perform a surface treatment. Test piece: A test piece having dimensions specified in JIS K6850 was produced in a room at a temperature of 23 C. and a humidity of 50% RH. Specifically, the epoxy resin-containing composition was applied to one of two adherends, the adherend was bonded to the other adherend so as to have a lap length of 12.5 mm and a thickness of an adhesive layer of about 0.2 mm, the epoxy resin-containing composition was cured at a temperature of 23 C. and a humidity of 50% RH, and the lap shear strength was measured after 24 hours from the starting point in time of curing of the epoxy resin-containing composition.

[0079] Measurement method: The lap shear strength was measured at a tensile speed of 2.0 mm/min in a room at a temperature of 23 C. and a humidity of 50% RH using a tensile tester specified in JIS K 6850. For the measurement, three test pieces were used, and the average value was taken as the numerical value of the lap shear strength.

Example 1

(Thiol Group-Containing Polyether Polymer)

[0080] In a 1 L reaction vessel, 250 g of a trifunctional polypropylene glycol (OH value: 510 mg KOH/polypropylene glycol) obtained by adding propylene oxide to glycerin and 1.5 g of stannic chloride pentahydrate were charged, the temperature was raised to 50 C., 248 g of epichlorohydrin (1.18 mol times the OH group of the trifunctional polypropylene glycol) was added dropwise over 1 hour, and the mixture was then stirred at 80 C. for 2 hours to obtain a halogen-terminated polyether polymer.

[0081] Then, the halogen-terminated polyether polymer was transferred to an airtight container, 15 g of citric acid was added, and the airtight container was sealed. To the sealed container, 365 g of an aqueous sodium hydrogen sulfide solution (concentration: 48%) was added dropwise, and the mixture was stirred at 90 C. for 5 hours. Then, the inorganic salt and water were removed to obtain a colorless and transparent liquid thiol group-containing polyether polymer. The [SH]/[S.sub.x] of the thiol group-containing polyether polymer was 9.6. The content of the thiol group was 15% by mass, the viscosity at 25 C. was 4 Pa.Math.s, the viscosity at 5 C. was 40 Pa.Math.s, and the content of chlorine was 0.08% by mass.

(Epoxy Resin-Containing Composition)

[0082] 10.0 g of a bisphenol A-type epoxy resin (jER 828 manufactured by Mitsubishi Chemical Group Corporation, epoxy equivalent: 184 to 194) as an epoxy resin, 8.0 g of the thiol group-containing polyether polymer as a thiol compound, and 1 g of an amine compound (EHC-30 manufactured by ADEKA CORPORATION) were mixed with a spatula under conditions of 23 C. and 50% RH for 60 seconds to obtain an epoxy resin-containing composition.

[0083] The pot life of the epoxy resin-containing composition was 3.0 minutes. The shore D hardness after 24 hours from the starting point in time of curing was 83, which was a sufficient hardness as an adhesive. The lap shear strength after 24 hours from the starting point in time of curing was 14 MPa, which was a sufficiently high numerical value as an adhesive. The results are shown in Table 1.

Comparative Example 1

(Thiol Group-Containing Polyether Polymer)

[0084] A commercially available thiol group-containing polyether polymer (QE-340M manufactured by Toray Fine Chemicals Co., Ltd.) was used.

[0085] The [SH]/[S.sub.x] of the thiol group-containing polyether polymer was 5.3. The content of the thiol group was 13% by mass, the viscosity at 25 C. was 14 Pa.Math.s, the viscosity at 5 C. was 160 Pa.Math.s, and the content of chlorine was 0.2% by mass.

(Epoxy Resin-Containing Composition)

[0086] An epoxy resin-containing composition was obtained in the same manner as in Example 1 except that the thiol group-containing polyether polymer was used as a thiol compound.

[0087] The evaluation results are shown in Table 1.

Comparative Example 2

(Thiol Group-Containing Polyether Polymer)

[0088] A commercially available thiol group-containing polyether polymer (GPM-800 manufactured by Huntsman International LLC) was used.

[0089] The [SH]/[S.sub.x] of the thiol group-containing polyether polymer was 6.4. The content of the thiol group was 12% by mass, the viscosity at 25 C. was 11 Pa.Math.s, the viscosity at 5 C. was 99 Pa.Math.s, and the content of chlorine was 0.03% by mass.

(Epoxy Resin-Containing Composition)

[0090] An epoxy resin-containing composition was obtained in the same manner as in Example 1 except that the thiol group-containing polyether polymer was used as a thiol compound.

[0091] The evaluation results are shown in Table 1.

TABLE-US-00001 TABLE 1 Compar- Compar- ative ative Example 1 Example 2 Example 1 QE GPM-800 Thiol [SH]/[S.sub.x] 9.6 5.3 6.4 group- Content of 15 13 12 containing thiol group polyether (% by mass) polymer Viscosity at 25 C. 4 14 11 (Pa .Math. s) Viscosity at 5 C. 40 160 99 (Pa .Math. s) Adhesive Epoxy resin 100 100 100 composition (parts by mass) Thiol (parts by 80 80 80 group- mass) containing polyether polymer Amine compound 10 10 10 (parts by mass) Pot life (min) 3.0 5.0 3.5 Hardness After 24 83 83 82 (Shore D) hours Lap shear After 24 14 14 12 strength hours (MPa)

[0092] As shown in Table 1, in the thiol group-containing polyether polymer of Example 1, the [SH]/[S.sub.x] is as high as 7.0 or more, the viscosity is low, and the workability is excellent. On the other hand, in the conventional thiol compounds according to Comparative Example 1 and Comparative Example 2, the [SH]/[S.sub.x] s are less than 7.0, and the viscosities are high.