Determination of the degree of branching

Abstract

The invention relates to a process for determining the degree of branching of modified polymers wherein the polymers are modified in the sense that their degree of branching after polymerization was increased once more, wherein the modified polymers are treated with a polar transformation mixture comprising a compound of general formula (I)
R.sup.1SSR.sup.1 (I)
wherein the Mooney viscosity (ML 1+4 at 100? C.) of the polymers is determined before and after the treatment with the polar transformation mixture and the degree of branching is determined.

Claims

1. A process for determining the degree of branching of modified diene polymers modified from original diene polymers to increase the degree of crosslinking/branching thereof, and the Mooney viscosity of the original diene polymers is unknown, the process comprising: determining the Mooney viscosity (ML 1+4 at 100? C.) of the modified diene polymers, treating the modified diene polymers with a transformation mixture, thereby forming further modified diene polymers, wherein the transformation mixture comprises a compound of general formula (I)
R.sup.1SSR.sup.1(I) where R.sup.1 in either occurrence is the same or different and is selected from a group consisting of moieties of formula (II)
C.sub.6(R.sup.2).sub.5(C?O)N(R.sup.3)C.sub.6(R.sup.2).sub.4(II) where R.sup.2 and R.sup.3 in each occurrence is the same or different and each represent a hydrogen radical, a linear or branched alkyl radical of 1 to 16 carbon atoms, a phenyl radical, or a cycloalkyl radical of 5 to 8 carbon atoms; moieties of formula (III) ##STR00011## where R.sup.4 in either occurrence is the same or different and represents a hydrogen, halogen, nitro or hydroxyl radical, a linear or branched alkyl radical of 1 to 12 carbon atoms, a linear or branched alkoxy radical of 1 to 12 carbon atoms, a phenyl radical, or a cycloalkyl radical of 5 to 8 carbon atoms, or the R.sup.4's combine to form the moiety of formula (IV); ##STR00012## where R.sup.5 in each occurrence is the same or different and represents a hydrogen or hydroxyl radical, a linear or branched alkyl radical of 1 to 12 carbon atoms, a linear or branched alkoxy radical of 1 to 12 carbon atoms, a phenyl radical, or a cycloalkyl radical of 5 to 8 carbon atoms; moieties of formula (V)
(R.sup.6O).sub.3Si(CH.sub.2).sub.n(Y).sub.m(V) where n is an integer from 1 to 12; m is from 0 to 4; R.sup.6 in each occurrence is the same or different and represents a linear or branched alkyl radical of 1 to 16 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms; Y represents sulphur, or a moiety of formula VIa, VIb, VIc, VId or VIe ##STR00013## where x is an integer from 1 to 8; p is an integer from 1 to 12; R.sup.8 in each occurrence is the same or different and represents a linear or branched alkyl radical of 1 to 16 carbon atoms, an alkoxy radical of 1 to 16 carbon atoms, a phenyl radical or a phenoxy radical; moieties of formula (VII)
(R.sup.9).sub.2N(C?Z)(VII) where Z represents sulphur or oxygen, R.sup.9 in either occurrence is the same or different and represents a linear or branched alkyl radical of 1 to 16 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms; or moieties of formula (VIII) ##STR00014## where R.sup.10 is the same or different and represents a linear or branched alkyl radical of 1 to 16 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms, determining the Mooney viscosity (ML 1+4 at 100? C.) of the further modified diene polymers, wherein the Mooney viscosity of the further modified diene polymers corresponds to the Mooney viscosity of the original diene polymers; and calculating the degree of branching of the modified diene polymers relative to the original diene polymers to by equation (I) wherein:
degree of branching in %=(K?L)/L*100 where K is the Mooney viscosity (ML 1+4 at 100? C.) of the modified diene polymers before treating with the transformation mixture, and L is the Mooney viscosity (ML 1+4 at 100? C.) of the further modified diene polymers after treatment with the transformation mixture.

2. The process according to claim 1, wherein the transformation mixture comprises 2,2-dibenzamidodiphenyl disulphide (DBD).

3. The process according to claim 1, wherein the transformation mixture comprises the compound of formula (IXa)
(EtO).sub.3SiC.sub.3H.sub.6S.sub.4C.sub.3H.sub.6Si(OEt).sub.3(IXa).

4. The process according to claim 1, wherein the transformation mixture comprises the compound of formula (IXb)
(EtO).sub.3SiC.sub.3H.sub.6S.sub.2C.sub.3H.sub.6Si(OEt).sub.3(IXb).

5. The process according to claim 1, wherein the transformation mixture comprises tetramethylthiuram disulphide.

6. The process according to claim 1, wherein the transformation mixture comprises transition metal salts, by way of activator, selected from the group consisting of Fe, Co, Cu, Ni, Mn, and Cr.

7. The process according to claim 6, wherein the Fe salts comprise Fe phthalocyanine or Fe hematoporphyrin.

8. The process according to claim 1, wherein the transformation mixture comprises, by way of activator, pentachlorothiophenol and salts thereof.

9. The process according to claim 1, wherein the transformation mixture further comprises an organic peroxide activator of formula (VIII)
R.sup.11OOR.sup.12,(VIII) where R.sup.11 and R.sup.12 are the same or different and each represent a hydrogen radical, a linear or branched alkyl radical of 1 to 16 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms, or a carboxyl radical R.sup.13(C?O), where R.sup.13 represents a linear or branched alkyl radical of 1 to 16 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms.

10. The process according to claim 1, wherein the transformation mixture further comprises waxes and/or fillers.

11. The process according to claim 1, wherein the treating step comprises mixing the modified diene polymer with the transformation mixture under thermal or mechanical input of energy.

12. The process according to claim 1, wherein the treating step comprises mixing the modified diene polymer with the transformation mixture in a mixer, in an extruder, or on a roll at a temperature of 70? C. to 160? C.

13. The process according to claim 1, wherein the transformation mixture is present in amounts of 0.01 to 2 wt %, based on 100 wt % of the modified diene polymer used.

14. The process according to claim 1, wherein the transformation mixture comprises: a) 5 to 100 wt % of one or more compounds of formula (I), b) optionally 0.01 to 5 wt % of activators, at the quantitative expense of compound of formula (I), c) optionally 0.01 to 90 wt % of waxes, at the quantitative expense of compound of formula (I), d) optionally 0.01 to 90 wt % of fillers, at the quantitative expense of compound of formula (I), based on 100 wt % of transformation mixture.

15. The process according to claim 1, wherein the modified diene polymers are in the form of a solid material.

16. The process according to claim 1, wherein: for the moieties of formula (II) R.sup.2 and R.sup.3 in each occurrence is the same or different and each represent a hydrogen radical, a linear or branched alkyl radical of 1 to 8 carbon atoms, a phenyl radical, or a cycloalkyl radical of 5 to 8 carbon atoms; for the moieties of formula (III) R.sup.4 in either occurrence is the same or different and represents a hydrogen, halogen, nitro or hydroxyl radical, a linear or branched alkyl radical of 1 to 8 carbon atoms, a linear or branched alkoxy radical of 1 to 8 carbon atoms, a phenyl radical, a cycloalkyl radical of 5 to 8 carbon atoms or the R.sup.4's combine to form the moiety of formula (IV); and R.sup.5 in each occurrence is the same or different and represents a hydrogen or hydroxyl radical, a linear or branched alkyl radical of 1 to 8 carbon atoms, a linear or branched alkoxy radical of 1 to 8 carbon atoms, a phenyl radical, or a cycloalkyl radical of 5 to 8 carbon atoms; for the moieties of formula (V) n is an integer from 1 to 6; m is from 0 to 2; R.sup.6 in each occurrence is the same or different and represents a linear or branched alkyl radical of 1 to 8 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms; x is an integer from 2 to 6; p is an integer from 1 to 6; and R.sup.6 in each occurrence is the same or different and represents a linear or branched alkyl radical of 1 to 8 carbon atoms, an alkoxy radical of 1 to 8 carbon atoms, a phenyl radical or a phenoxy radical; for the moieties of formula (VII) R.sup.9 in either occurrence is the same or different and represents a linear or branched alkyl radical of 1 to 8 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms; and for the moieties of formula (VIII) R.sup.10 is the same or different and represents a linear or branched alkyl radical of 1 to 8 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms.

17. The process according to claim 16, wherein the transformation mixture further comprises an organic peroxide activator of formula (VIII)
R.sup.11OOR.sup.12,(VIII) where R.sup.11 and R.sup.12 are the same or different and each represent a hydrogen radical, a linear or branched alkyl radical of 1 to 8 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms, or a carboxyl radical R.sup.13(C?O), where R.sup.13 represents a linear or branched alkyl radical of 1 to 8 carbon atoms, a phenyl radical or a cycloalkyl radical of 5 to 8 carbon atoms.

18. The process according to claim 17, wherein the treating step comprises mixing the modified diene polymer with the transformation mixture at a temperature of 80? C. to 120? C.

Description

EXAMPLE 1: DETERMINING A 55% DEGREE OF BRANCHING IN A MODIFIED POLYMER OF LOW MOONEY VISCOSITY

(1) 1a) Polymerization:

(2) A dry, nitrogen-inertized 20 L steel autoclave was charged with 8500 g of hexane (dried over molecular sieve), 1300 g of 1,3-butadiene, 25 mmol of a 20% solution of diisobutylaluminium hydride in hexane, 1.44 mmol of a 10% solution of ethylaluminium sesquichloride in hexane, and also 1.44 mmol of a 40% solution of neodymium versatate in hexane. The autoclave contents were heated to 65? C. with stirring and polymerized for 60 min with stirring. The temperature in the reactor was maintained at 70? C. The polymerization was stopped by admixture of 6.5 g of lauric acid (0.5 phr) and stabilized by admixture of 1.3 g of Irganox 1520.

(3) A conversion test sample was taken. Butadiene conversion after the polymerization was found to be 95%.

(4) Original Mooney viscosity (ML 1+4 at 100? C.): 29.8 MU;

(5) microstructure: 97.3 wt % of 1,4-cis, 1.8 wt % of 1,4-trans, 0.8 wt % of 1,2-vinyl

(6) 1b) Modification:

(7) 720 g of polymer solution 1 a) were transferred into a 2 L reactor. The solution was admixed with a solution of 0.187 g of disulphur dichloride (0.2 phr) in 10 mL of hexane at 65? C. for modification. The solution was stirred at 65? C. for a further 30 min. The polymer was precipitated by introduction into 5 kg of ethanol, stabilized with further Irganox 1520 (0.1 phr) and vacuum dried at 70? C.

(8) Final Mooney viscosity (ML 1+4 at 100? C.): 45.6 MU corresponds to K as per equation (I) for computing the degree of branching

(9) Gel content<0.3 wt %

(10) 1c) Determination of Degree of Branching

(11) A mixture of 4 g of DBD with 6 g of talcum and 0.08 g of iron phthalocyanine was mixed in a mortar by way of transformation mixture.

(12) 70 g of the polymer from 1b) were admixed with 0.44 g of the transformation mixture on a laboratory roll at 120? C. Roll nip was 0.4 mm, roll diameter was 10 cm. Rolling time was 15 min.

(13) Mooney viscosity (ML 1+4 at 100? C.): 29.4 MU corresponds to L as per equation (I) for computing the degree of branching [%]=(K?L)/L*100=(45.6?29.4)/29.4*100=55

(14) Degree of branching: 55%

EXAMPLE 2: DETERMINING A 17% DEGREE OF BRANCHING IN A MODIFIED POLYMER OF LOW MOONEY VISCOSITY

(15) 2a) Polymerization:

(16) The polymer solution of Example 1 was used.

(17) 2b) Modification:

(18) 720 g of polymer solution from 1a) were transferred into a 2 L reactor. The solution was admixed with a solution of 0.13 g of disulphur dichloride in 10 mL of hexane at 65? C. for modification. The solution was stirred at 65? C. for a further 15 min. The polymer was precipitated by introduction into 5 kg of ethanol, stabilized with further Irganox 1520 (0.1 phr) and vacuum dried at 70? C.

(19) Final Mooney viscosity (ML 1+4 at 100? C.): 35.9 MU, corresponds to K of equation (I).

(20) Gel content<0.3 wt %

(21) 2c) Determination of Degree of Branching

(22) A mixture of 4 g of DBD with 6 g of talcum and 0.08 g of iron phthalocyanine was mixed in a mortar by way of transformation mixture.

(23) 70 g of the polymer from 2b) were admixed with 0.44 g of the transformation mixture on a laboratory roll at 120? C. Roll nip was 0.4 mm, roll diameter was 10 cm. Rolling time was 15 min.

(24) Mooney viscosity (ML 1+4 at 100? C.): 30.8 MU, corresponds to L of equation (I).

(25) Degree of branching: 17%

(26) Computed as per equation (I): degree of branching=(K?L)/L*100=(35.9?30.8)/30.8*100=17%

EXAMPLE 3: DETERMINING A 53% DEGREE OF BRANCHING IN A MODIFIED POLYMER OF HIGH MOONEY VISCOSITY

(27) 3a) Polymerization:

(28) A dry, nitrogen-inertized 20 L steel autoclave was charged with 8500 g of hexane (dried over molecular sieve), 1300 g of 1,3-butadiene, 21 mmol of a 20% solution of diisobutylaluminium hydride in hexane, 1.44 mmol of a 10% solution of ethylaluminium sesquichloride in hexane, and also 1.44 mmol of a 40% solution of neodymium versatate in hexane. The autoclave contents were heated to 73? C. with stirring and polymerized for 60 min with stirring. The temperature in the reactor was increased to 90? C. The polymerization was stopped by admixture of 6.5 g of stearic acid (0.5 phr).

(29) A conversion test sample was taken. Butadiene conversion after the polymerization was found to be 98.7%.

(30) Original Mooney viscosity (ML 1+4 at 100? C.): 40 MU;

(31) Microstructure: 97.5 wt % of 1,4-cis, 2.0 wt % of 1,4-trans, 0.5 wt % of 1,2-vinyl

(32) 3b) Modification:

(33) The polymer solution was admixed with 3.33 g of disulphur dichloride (0.3 phr) at 95? C. for modification. The solution was stirred at 95? C. for a further 10 min. The polymer was precipitated by introduction into 5 kg of ethanol, stabilized with Irganox 1520 (0.2 phr) and vacuum dried at 70? C.

(34) Final Mooney viscosity (ML 1+4 at 100? C.): 62.7 MU, corresponds to K of equation (I).

(35) Gel content<0.3 wt %

(36) 3c) Determination of Degree of Branching

(37) A mixture of 4 g of DBD with 6 g of talcum and 0.08 g of iron phthalocyanine was mixed in a mortar by way of transformation mixture.

(38) In a Brabender type internal mixer turning at 20 rpm, 230 g of rubber were mixed and heated to 130? C. in the course of 5 min. 1.44 g of transformation mixture from Example 1c) were added thereto and mixed in under the same conditions for 1 min.

(39) Mooney viscosity (ML 1+4 at 100? C.): 41.0 MU, corresponds to L of equation (I)

(40) Degree of branching: 53%

(41) Computed as per equation (I): degree of branching=(K?L) L*100=(62.7?41)/41*100=53

COMPARATIVE EXAMPLE 4

(42) To carry out these tests, 70 g of the modified polymer from Example 3b) were stored for 60 min in a drying cabinet at 145? C. without the addition of a transformation mixture. The polymer is found to remain stable.

(43) Polymer before the treatment Mooney viscosity (ML 1+4 at 100? C.)=62.7 MU; MSR 0.46

(44) Polymer after treatment: Mooney viscosity (ML 1+4 at 100? C.)=62.8 MU; MSR 0.46

(45) .fwdarw. no branching

COMPARATIVE EXAMPLE 5

(46) These tests were carried out by rolling 200 g of the modified polymer from Example 3b) without the addition of a transformation mixture at 130? C. for 15 min in a roll nip of 0.5 mm and a roll diameter of 10 cm without further additions. The polymer is found to remain stable.

(47) Polymer before the treatment: Mooney viscosity (ML 1+4 at 100? C.)=62.7 MU

(48) Polymer after the treatment: Mooney viscosity (ML 1+4 at 100? C.)=62.0 MU

(49) .fwdarw. no branching