Modified diene polymer and method for producing same

Abstract

A modified diene polymer according to an embodiment comprises a diene polymer having graft polymerized thereon a vinylphosphonic acid represented by the following formula (1). In the formula (1), R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R.sup.3 represents a hydrogen atom or a methyl group. ##STR00001##

Claims

1. A modified diene rubber comprising a diene rubber having graft polymerized thereon a monomer consisting of a vinylphosphonic acid represented by the following formula (1): ##STR00006## wherein R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R.sup.3 represents a hydrogen atom or a methyl group, wherein the modified diene rubber has a glass transition temperature of −70° C. to −20° C. and has a weight average molecular weight of 400,000 to 2,600,000.

2. The modified diene rubber according to claim 1, having a skeleton comprising the diene rubber and a graft chain represented by the following formula (2) bonded to the skeleton: ##STR00007## wherein R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R.sup.3 represents a hydrogen atom or a methyl group, n is an integer of 0 or more, and * is a bonding position to a carbon atom in the diene rubber.

3. The modified diene rubber according to claim 2, having a structural unit represented by the following formula (3): ##STR00008## wherein A represents a graft chain represented by the formula (2).

4. The modified diene rubber according to claim 1, wherein the diene rubber is at least one selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, acrylonitrile-butadiene rubber and butyl rubber.

5. The modified diene rubber according to claim 1, wherein R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.

6. A method for producing a modified diene rubber, comprising graft polymerizing a monomer consisting of a vinylphosphonic acid represented by the following formula (1) on a diene rubber: ##STR00009## wherein R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R.sup.3 represents a hydrogen atom or a methyl group,. wherein the modified diene rubber has a glass transition temperature of −70° C. to −20° C. and has a weight average molecular weight of 400,000 to 2,600,000.

7. The method for producing a modified diene rubber according to claim 6, wherein the amount of the vinylphosphonic acid added is 0.20 to 4.0 moles per 1 kg of the diene rubber.

8. The method for producing a modified diene rubber according to claim 6, wherein a rubber latex is used as the diene rubber.

9. The method for producing a modified diene rubber according to claim 6, comprising adding the vinylphosphonic acid and a polymerization initiator to a latex or solution of the diene rubber to conduct a graft polymerization, and coagulating and drying the resulting latex or solution containing the diene rubber.

Description

EXAMPLES

(1) Examples of the present invention are described below, but the present invention is non construed as being limited to those examples.

(2) Each measurement method of the modified diene polymer is as follows.

.SUP.31.P-NMR

(3) .sup.31P-NMR quantitative spectrum was measured by 400 ULTRASHIELD™ PLUS manufactured by BLUKER using a measurement sample dissolved in deuterated chloroform. Chemical shift correction was conducted using triphenylphosphine as an external standard.

Modification Ratio

(4) Modification ratio was calculated from .sup.13C-NMR quantitative spectrum. .sup.13C-NMR quantitative spectrum was measured by 400 ULTRASHIELD™ PLUS manufactured by BLUKER using a measurement sample dissolved in deuterated chloroform. Modification ratio that is a ratio of the number of moles of structural units having graft chain introduced therein to the number of moles of total structural units constituting the modified diene polymer was calculated by integral ratio of the spectrum derived from a graft chain (using spectrum of 16 ppm) and the spectrum derived from a main chain (using spectrum of 23 ppm).

Weight Average Molecular Weight (Mw)

(5) Mw in terms of polystyrenes was obtained by the measurement with gel permeation chromatography (GPC). In detail, a measurement sample dissolved in tetrahydrofuran (THF) was used. Using LC-20A manufactured by Shimadzu Corporation, after passing the sample through a filter, the sample was passed through a column (Shodex KL-806) at a temperature of 40° C. in a flow rate of 1.0 mL/min, and then detected by a differential bending detector (RI).

Glass Transition Temperature (Tg)

(6) The glass transition temperature was measured by a differential scanning calorimetry (DSC) method in a temperature rising rate of 20° C./min (measurement temperature range: −130° C. to 200° C.) according to JIS K7121.

(7) Details of the reagents used in the examples are as follows.

(8) IR latex: Isoprene rubber latex, Califlex IR0401 SU Latex manufactured by KRATON Polymer Japan

(9) Disodium hydrogen phosphate: manufactured by FUJIFILM Wako Pure Chemical Corporation

(10) Sodium dodecyl sulfate: manufactured by FUJIFILM Wako Pure Chemical Corporation

(11) Tert-butyl hydroperoxide: manufactured by Tokyo Chemical Industry Co., Ltd.

(12) Tetraethylene pentamine: manufactured by Tokyo Chemical Industry Co., Ltd.

(13) IR2200: Isoprene rubber, JSR IR2200 manufactured by JSR Corporation

(14) Toluene: manufactured by Nacalai Tesque

(15) Vinylphosphonic acid: manufactured by Tokyo Chemical Industry Co., Ltd.

(16) Diethyl vinylphosphonate: manufactured by Tokyo Chemical Industry Co., Ltd.

Example 1

(17) Water was added to IR latex to prepare 103 g of a latex having a rubber solid content concentration of 20% by mass. 0.10 g of sodium dodecyl sulfate was added to the latex, followed by stirring for 1 hour in a nitrogen atmosphere. Thereafter, 0.18 mL of tert-butyl hydroperoxide, 0.25 mL of tetraethylene pentamine and 0.54 g of vinylphosphonic acid were further added, followed by stirring at 30° C. for 2 hours. The amount of the vinylphosphonic acid added is 0.25 moles per 1 kg of the isoprene rubber. The reaction solution obtained was added dropwise to acetone to coagulate a rubber component. The rubber component obtained was washed with water and dried at 50° C. under reduced pressure. As a result, a modified isoprene rubber having vinylphosphonic acid graft polymerized thereon was obtained as a target product. It was confirmed from .sup.31P-NMR spectrum of the product obtained that phosphonic acid groups were introduced in the isoprene rubber polymer.

(18) The modified isoprene rubber obtained had .sup.31P-NMR (CDCl.sub.3), d=23.1 (br). Furthermore, the modification ratio was 10 mol %, Mw was 564,000 and Tg was −62° C.

Example 2

(19) Water was added to IR latex to prepare 200 g of a latex having a rubber solid content concentration of 20% by mass. 0.13 g of sodium dodecyl sulfate was added to the latex, followed by stirring for 1 hour in a nitrogen atmosphere. Thereafter, 0.36 mL of tert-butyl hydroperoxide, 0.50 mL of tetraethylene pentamine and 6.4 g of vinylphosphonic acid were further added, followed by stirring at 30° C. for 2 hours. The amount of the vinylphosphonic acid added is 1.5 moles per 1 kg of the isoprene rubber. The reaction solution obtained was added dropwise to acetone to coagulate a rubber component. The rubber component obtained was washed with water and dried at 50° C. under reduced pressure. As a result, a modified isoprene rubber having vinylphosphonic acid graft polymerized thereon was obtained as a target product. It was confirmed from .sup.31P-NMR spectrum of the product obtained that phosphonic acid groups were introduced in the isoprene rubber polymer.

(20) The modified isoprene rubber obtained had .sup.31P-NMR (CDCl.sub.3), d=23.1 (br). Furthermore, the modification ratio was 10 mol %, Mw was 565,000 and Tg was −62° C.

Example 3

(21) Water was added to IR latex to prepare 103 g of a latex having a rubber solid content concentration of 20% by mass. 0.11 g of disodium hydrogen phosphate and 0.10 g of sodium dodecyl sulfate were added to the latex, followed by stirring for 1 hour in a nitrogen atmosphere. Thereafter, 0.18 mL of tert-butyl hydroperoxide, 0.25 mL of tetraethylene pentamine and 3.45 g of diethyl vinylphosphonate were further added, followed by stirring at 30° C. for 2 hours. The amount of the diethyl vinylphosphonate added is 1.05 moles per 1 kg of the isoprene rubber. The reaction solution obtained was added dropwise to acetone to coagulate a rubber component. The rubber component obtained was washed with water and dried at 50° C. under reduced pressure. As a result, a modified isoprene rubber having diethyl vinylphosphonate graft polymerized thereon was obtained as a target product. It was confirmed from .sup.31P-NMR spectrum of the product obtained that phosphonate groups were introduced in the isoprene rubber polymer.

(22) The modified isoprene obtained had .sup.31P-NMR (CDCl.sub.3), d=36.7 (br). Furthermore, the modification ratio was 10 mol %, Mw was 2,060,000 and Tg was −62° C.

Example 4

(23) 6.0 g of IR 2200 was dissolved in 200 mL of toluene to prepare a rubber solution. 48 mg of tert-butyl hydroperoxide, 70 mg of tetraethylene pentamine and 0.97 g of vinylphosphonic acid were added to the rubber solution obtained, followed by stirring at 30° C. for 2 hours. The amount of the vinylphosphonic acid added is 1.5 moles per 1 kg of the isoprene rubber. The reaction solution obtained was added dropwise to acetone to coagulate a rubber component. The rubber component obtained was washed with water and dried at 50° C. under reduced pressure. As a result, a modified isoprene rubber having vinylphosphonic acid graft polymerized thereon was obtained as a target product. It was confirmed from .sup.31P-NMR spectrum of the product obtained that phosphonic acid groups were introduced in the isoprene rubber polymer.

(24) The modified isoprene rubber obtained had .sup.31P-NMR (CDCl.sub.3), d=19.8 (br). Furthermore, the modification ratio was 2 mol %, Mw was 485,000 and Tg was −65° C.

Example 5

(25) 6.0 g of IR 2200 was dissolved in 200 mL of toluene to prepare a rubber solution. 96 mL of tert-butyl hydroperoxide, 140 mg of tetraethylene pentamine and 1.94 g of vinylphosphonic acid were added to the rubber solution obtained, followed by stirring at 30° C. for 2 hours. The amount of the vinylphosphonic acid added is 3.0 moles per 1 kg of the isoprene rubber. The reaction solution obtained was added dropwise to acetone to coagulate a rubber component. The rubber component obtained was washed with water and dried at 50° C. under reduced pressure. As a result, a modified isoprene rubber having vinylphosphonic acid graft polymerized thereon was obtained as a target product. It was confirmed from .sup.31P-NMR spectrum of the product obtained that phosphonic acid groups were introduced in the isoprene rubber polymer.

(26) The modified isoprene rubber obtained had .sup.31P-NMR (CDCl.sub.3), d=20.3 (br). Furthermore, the modification ratio was 3 mol %, Mw was 626,000 and Tg was −64° C.

(27) Tensile product of the unvulcanized modified isoprene rubbers of Examples 1 and 3 were measured. As Comparative Example 1, the tensile product of an unmodified isoprene rubber was measured. As the unmodified isoprene rubber, an unvulcanized isoprene rubber obtained by adding dropwise the IR latex to acetone to coagulate and after washing with water, drying at 50° C. under reduced pressure was used. The measurement method of the tensile product is as follows.

Tensile Product

(28) An unvulcanized rubber was molded into a sheet form having a thickness of 5 mm. A sample having 60 mm vertical and 20 mm horizontal cut out of the sheet was subjected to a tensile test using an autograph, and tensile product (TB (tensile strength)×EB (elongation at break)) as fracture characteristics was obtained. Fracture characteristics are excellent as the numerical value is large.

(29) The results are shown in Table 1 below. In the modified isoprene rubbers of Examples 1 and 3, the tensile product is improved in the evaluation of an unvulcanized rubber alone as compared with the unvulcanized isoprene rubber of Comparative Example 1, and the effect of improving properties by the modification with a vinylphosphonic acid was recognized.

(30) TABLE-US-00001 TABLE 1 Tensile product [MPa .Math. %] Modified isoprene of Example 1 78.8 Modified isoprene of Example 3 60.8 Unmodified isoprene of 59.5 Comparative Example 1