NL1008677C2 - Fatty acid-modified amines as rubber additives. - Google Patents

Description

- 1 -

FATTIC ACID MODIFIED AMINES AS RUBBER ADDITIVES

5

The invention relates to fatty acid modified amines, as well as rubber compositions containing fatty acid modified amines, and methods of treating rubbers with fatty acid modified amines.

Fatty acid modified amines, rubber compositions containing fatty acid modified amines, and methods of treating rubbers with fatty acid modified amines are known from EP-146,579, which describes, for example, fatty acid salts of N-alkyl alkylene diamines and rubber compositions thereof, as well as a process for treating rubber with said fatty acid salts of N-alkyl alkylene diamines.

The fatty acid modified amines of EP-146,579 are used as vulcanization accelerators. Vulcanization accelerators are compounds that accelerate the vulcanization of rubber. According to EP-25 146,579, the action of said fatty acid modified amines relies on their ability to dissociate at least partially upon heating to at least the vulcanization temperature of a rubber composition containing said fatty acid modified amines in a secondary amine, respectively, which functions as a vulcanization accelerator. and a fatty acid that controls, inter alia, the rate at which vulcanization occurs.

1 008677 -2 -

However, the drawback of the fatty acid salts of N-alkyl alkylene diamines according to EP-146,579 is that these compounds are secondary amines, or give rise to secondary amines when heated, which, during the vulcanization of a rubber composition, causes these fatty acid salts of N-alkyl alkylene diamines, N-nitrosamines may be formed. N-nitrosamines are carcinogenic compounds. It is not desirable in the rubber industry to use rubber additives which may give rise to carcinogenic compounds; there is thus a great need for rubber additives, in this case vulcanization accelerators, which do not give rise to the formation of N-nitrosamines (Th. Kleiner, "Prospects 15 for Accelerators Based on Safe Amines", Kautschuk Gummi Kunststoffe (KGK) 50, Jahrgang 1 / 97).

The object of the invention is to provide fatty acid-modified amines that do not form N-nitrosamines, as well as to provide rubber compositions containing the fatty acid-modified amines of the invention, and to provide a process for the treatment of rubbers with the fatty acid modified amines according to the invention.

The inventors have now found that a fatty acid modified amine, which mainly contains primary and tertiary amino groups where at least one tertiary amino group is present and the fatty acid modification is present on at least one primary amino group, is excellent as a rubber additive that the vulcanization rate of rubber ..

: 1008677-3 - increases, in particular, yields a vulcanization rate comparable to that obtained with the fatty acid modified amines of EP-146,579, but without the said formation of N-nitrosamines. The invention is all the more surprising because it is known, inter alia, from EP-146,579 that fatty acid salts of primary amines are unsuitable as rubber additives for a number of reasons and give rise to a rubber composition with undesirable properties.

Amine, which mainly contains primary and tertiary amino groups in which at least one tertiary and one primary amino group is present, is understood to be an amine in which the sum of the primary and tertiary amino groups present is at least 80 mol% of the total of all amino groups present. Preferably, the total number of the primary and secondary groups is 85 mol%, more preferably 90 mol%. The amine may also contain other functional groups than amino groups.

Surprisingly, it has also been found that in rubbers filled with silica-based mineral fillers, the fatty acid-modified amines of the invention not only increase the vulcanization rate but also significantly improve the dispersion of the mineral filler in the rubber phase, thereby obtaining a rubber composition can be obtained with properties comparable to those of a rubber composition containing the widely used dispersant Si-69 (Degussa, Switzerland).

As the amine, which mainly contains primary and 1008677-4 tertiary amino groups, wherein at least one tertiary and one primary amino group is present, a branched organic compound is preferably chosen, in which a main chain, main molecule or atom 5 is present, from which at least one side chain branches off. . The branched organic compound can contain multiple side chains. The tertiary and primary amino groups can be present in the core, in the main chain and in the side chain. In turn, another side chain can branch from an atom in the side chain, in which both primary and tertiary amino groups can be present. The primary amino group is preferably terminal in the main chain or in the side chain. The tertiary amino group is pre-eminently suitable for realizing a chain branching, wherein the nitrogen atom functions as a branching point.

Suitable examples of such branched organic compounds are branched polymers, especially highly branched polyalkyleneimine, dendritically branched polyalkyleneimine, for example primary amino group-terminated polypropyleneimine, such as described in WO-A-93 14147 and WO-A-95 02008 and aminoalkylamines.

Suitable examples of highly branched polyalkylene imines are polyalkylene imines with an alkylene group having 2 to 25 carbon atoms, for example | ethylene or propylene. A suitable example is polyethyleneimine, for example described in US-A-4631337.

Suitable examples of aminoalkylamines are aminoalkylamines with an alkyl group having 1 to 25 carbon atoms, more preferably tertiary alkylamino; 1 008677-5 amines, for example tris- (2-aminoethyl) amines.

For the purposes of this application, a dendrimer or dendritically branched organic compound is understood to mean a three-dimensional, highly branched oligomer or polymer molecule, which is generally composed of a core, a number of generations of branches and a number of end groups. A generation of branches is made up of structure-10 units that are radially bonded to the core or to the structure units of the previous generation and extend away from the core. A structural unit is provided with at least two monofunctional groups or a multifunctional group, for example an amino-15 group. Multifunctional means a functionality of 2 or higher. A new structural unit can link to each functionality, creating a higher generation of branches. The sequence of the different generations of branches is the branch structure. The structural units can either be the same for each generation or differ per generation. At the last atom of the last generation of branches are the functional end groups, which may optionally still be modified, for example with a fatty acid.

For the purposes of this invention, dendrimers also include dendrimers having defects in the structural units or in the branching structure and asymmetric dendrimers.

For the purposes of this application, primary amino group-terminated dendrimer or 1008677-6 dendrirer with terminal primary amino groups includes a dendrimer in which at least part of the functional end groups are primary amino groups. In the context of this application, a modified end group is understood to mean a chemically altered end group.

Preferably, a fatty acid-modified dendrimer is selected with terminal fatty acid-modified primary amino groups and with 10 tertiary amino groups in the branches and / or in the nucleus, the N atom of the tertiary amino group serving as the branch point.

For the purposes of this application, fatty acid-modified primary amino group is understood to mean a primary amino group that has been modified using a fatty acid to either an amide group or a fatty acid ammonium salt group, with the oxycarbonyl ion of the fatty acid as the counterion. As fatty acid, a long-chain fatty acid with 10 to 100 carbon atoms, for example stearic acid, lauric acid, palmitic acid and oleic acid, is chosen. The fatty acid modified amines of the invention can be obtained by reacting a fatty acid with a suitable amine according to methods known to those skilled in the art.

The fatty acid-modified amines according to the invention are preferably compounds according to Formula 1: 30 Μ- (NH) x (NHCOR) v (NH + “OOCR) z (1) 2 A 1 '3 2 1 0 - RR 77 - 7 wherein M is a three-dimensional, branched oligomer or polymer molecule, generally composed of a core and a number of generations of branches n, n = 1 to 10; 5 wherein a branching group may contain a primary amino group (NH2), fatty acid amide group (NHCORj) or a fatty acid ammonium salt group (NH3 + "OOCR2); where x is equal to 0 to n1, y and z may each independently be equal to o to n, 10 with the proviso that the sum of y and z is at least equal to 1 and the sum of x, y and z is equal to or smaller than n; where Rx and R2, each independently, are equal to an alkyl group of 1 to 100 carbon atoms For example, the compound according to

Formula 1 derived from a polypropylene imine dendrimer with a core, based on diaminobutane and with branches, based on acrylonitrile, in particular 4-cascade: 1,4-diamino-butane [4] -propylamine 20 (n = 4), 8 cascade: 1,4-diaminobutane [4] :( 1-azabutylidene) 4: propylamine (n = 8), 16-cascade: 1,4-diaminobutane [4]: (1-azabutylidene) 12: propylamine (n = 16) and 32-cascade: 1,4-diaminobutane [4]: (1-azabutylidene) 28: propylamine (n = 32) (for the nomenclature of dendrimers, see Newkome J. Polymer Science. Part A: Polymer Chemistry, 31 (1993), biz. 641-651).

Preferably 4-cascade: 1,4-diaminobutane [4]: propylamine (n = 4), wherein two or more primary amino groups were modified into fatty acid amide groups, fatty acid 1003377-8 ammonium salt groups or a combination thereof, respectively. .

A further advantage of the fatty acid-modified polypropylene imine dendrimers according to the invention is the low volatility of said compounds, which makes the processing of said compounds into a rubber very attractive industrially.

The invention also relates to a rubber composition containing at least one rubber and a fatty acid modified amine according to the invention. Surprisingly, it was found that a rubber composition according to the invention can not only be vulcanized more quickly using the fatty acid-modified amines according to the invention, but that the rubber composition also showed good mechanical properties, in particular good hardness, tensile strength, elongation at break , tear strength and compressibility, comparable to the mechanical properties obtained with the commercially available and widely used dispersant Si-69 (Degussa, Switzerland).

For the purposes of this application, a rubber is understood to mean a hydrocarbon rubber, for example natural rubber (NR), butyl rubber (optionally halogenated or cross-linked with, for example, divinyl benzene), styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR) (both rubbers also in their hydrogenated form, viz. HSBR and HNBR, respectively, ~ 30 EPDM (a rubber obtained from ethylene, an α-olefin, especially propylene, and optionally a 1008677-9-diene as the third monomer, usually dicyclopentadiene and in especially ethylene-norbornene or vinyl norbornene), and other rubbers A list of suitable rubbers can be found in W. Hofmann's 5 Rubber Technology Handbook Hanser Verlag, Munich, 1989.

The rubber composition may also contain rubber additives commonly used in said rubbers, such as oil, carbon black, pigments, stabilizers, fillers and the like, which are well known to those skilled in the art.

The amount of fatty acid-modified amine of the invention in the rubber composition is not critical and can be freely selected by those skilled in the art. In particular, an amount of 0.1-10% by weight, calculated relative to the total weight of the rubber composition, is selected.

The invention also relates to a method for treating a rubber with a fatty acid-modified amine according to the invention.

The method includes at least contacting the rubber with the fatty acid-modified amine of the invention. Contacting can be done in any manner known to the person skilled in the art, for example by mixing.

According to a first embodiment of the method, the rubber, the fatty acid-modified amine according to the invention and optional rubber additives, for example silica-based fillers, oil and sulfur, are mixed at elevated temperature. Then, the thus obtained 1 008677-10 rubber composition is vulcanized at, for example, 160 ° C.

According to a second embodiment, the fatty acid modified amine of the invention is formed in the rubber composition by contacting the rubber with a suitable amine and a suitable fatty acid.

The method is further illustrated by the following examples without being limited thereto.

Examples

Preparation of rubber compounds

A number of rubber compositions were prepared according to the recipe below by mixing the components together according to a method described in: Ismail, Freakley, Sutherland and Sheng, Eur.Polym. Ilu (11), pp. 1109-1117.

i 20 Component_Weight parts

Natural rubber (type SMR 10) 100 ί Si02 (Ultrasil VN3) 30

Zinc oxide 5

Stearic acid 3 25 S-80 3.13 TMTD-80 1 CBS-80% 0.63

Vulcanization accelerator / dispersant 2 30 TMTD: 2,2,4-Trimethyl-1,2-dihydroquinoline 1008677 - 11 - CBS: N-cyclohexylbenthiazyl sulphenamide

The vulcanization was carried out at two temperatures, namely at 180 eC (Comparative Examples 5 A, B and C and Examples I and II) and at 160 eC (Examples III-VII).

As vulcanization accelerator or dispersant, the following compounds were chosen: - Si-69 (Degussa, Switzerland), a commercially available and widely used dispersant, - - EN-444 (Akzo Nobel, the Netherlands), a compound according to EP-146,579 (see also: Ismail, Freakley, Sutherland and Sheng, Eur.Polym. J. (11), pp. 1109-1117) 15 - DAB (Am) 4 (4-cascade: 1,4-diamino-butane [4]: propylamine) and DAB (Am) 8 (8-cascade: 1,4-diaminobutane [4] :( 1-azabutylidene 4: propylamine), both polypropylene imine dendrimers available as Astramol * enddrimers (DSM, The Netherlands) and whose end groups were modified with stearic acid to form compounds of the following end group composition (number of primary amino, stearamide and fatty acid ammonium salt groups): 1008677 - 12 ->

Compound_amine_amino stearamide ammonium A DAB (Am) 4 0 2 2 B DAB (Am) 4 0 4 0 C DAB (Am) 422 0 5 D DAB (Am) 4 0 0 4 E DAB (Am) 420 2 F DAB (Am) e4 2 2 10 Examples I and II and Comparative Examples A, B and C;

Five different rubber compositions were prepared according to the above method and were vulcanized at 180 eC. A number of mechanical properties were determined according to ISO standardized measuring methods. The results are shown in Table 1.

The results show that the rubber additives according to the invention exhibit a comparable vulcanization speed as the vulcanization accelerator according to EP-146,579 (Comparative Example C).

Furthermore, the rubber compositions according to the invention (Examples I and II) exhibit hardness, tensile strength, elongation at break, tear strength and compressibility comparable to that of the rubber compositions obtained with the vulcanization accelerator according to EP-146,579 (Comparative example * C).

Noteworthy is also the Mooney viscosity, 1008677 - 13 - t which is higher for the rubber compositions according to the invention than for the rubber composition containing the vulcanization accelerator according to EP-146,579 (Comparative example C) (which leads to a reduced viscosity compared to the viscosity of the rubber composition that does not contain a vulcanization accelerator (Comparative Example A)). The increased viscosity is attributed to an increased interaction between the rubber and the mineral filler and is indicative of an improved dispersion of the mineral filler in the rubber (see also Example VIII).

The Mooney viscosity is even as good for rubber additive A as the viscosity of a rubber composition containing the widely used dispersant Si-69 (Comparative Example B).

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Example VIII

To illustrate the good dispersion properties of the fatty acid modified amines of the invention for silica-based mineral fillers, the following experiment was performed. In a cuvette, 2 mg of a compound was added to 10 ml of heptane in which 25 mg of silica was dispersed. The cuvette was shaken for 15 minutes and then transferred to a spectrophotometer where the extinction at 446 nm was monitored as a function of time, which is equivalent to determining the rate at which the silica sedimented under gravity. In Table 3, the absorbance was tabulated after 100 seconds for a number of compounds, including the fatty acid modified amines of the | invention. A high absorbance indicates a low sedimentation rate of the silica, and thus a good dispersion of the silica. It is clear that the fatty acid modified amines of the invention are capable of dispersing silica better than, for example, EN-444 (according to EP-146,579) which does not function well as a dispersant and Si-69.

t 1008677 - 17 -

Connection Extinction after 100 sec.

B 0.18 D 0.10 Ë 0.08 C 0.08 A 0.06

Si-69 0.03 without 0.02 stearic acid 0.01 DAB (Am) 4 0.01 EN-444 0.01

Table 3: Extinction of a dispersion of silica in heptane after 100 seconds for some compounds added to the dispersion.

1008677

Claims (12)

1. Fatty acid-modified amine, characterized in that the amine mainly contains primary and tertiary amino groups, wherein at least one tertiary amino group is present and the fatty acid modification is present on at least one primary amino group. Fatty acid modified amine according to claim 1, 10, characterized in that the amine is a branched organic compound, in which a main chain, main molecule or atom is present from which at least one side chain branches. Fatty acid modified amine according to claim 2, characterized in that the branched organic compound is selected from the group of branched polyalkylene imines, dendritically branched polyalkylene imines and aminoalkylamines. Fatty acid-modified amine according to claim 3, characterized in that the dendritically branched polyalkylene imine is selected from the group consisting of 4-cascade: 1,4-diamino-butane [4]: propylamine and 1,4-cascade: 1,4 diaminobutane [4] :( 1-azabutylidene) 4: propylamine. Fatty acid modified amine according to any one of claims 1-4, characterized in that the fatty acid modified primary amino group is a fatty acid amide group or a fatty acid ammonium salt group. 1008677 4. - 19 - Fatty acid modified amine according to any one of claims 1 to 5, characterized in that the fatty acid is selected from the group consisting of stearic acid, lauric acid, palmitic acid and oleic acid. 7. Fatty acid-modified amine of Formula 1: __________ M- (NH2) x (NHCOR2) y (NH3 + "OOCR2) z (1) wherein M is a three-dimensional, branched oligomer 10 or polymer molecule, which is generally composed of a nucleus and a number of generations - branches n, n = 1 to 100, whereby a branch as end group can contain a primary amino group (NH2), fatty acid amide group (NHCORj.) or a fatty acid ammonium salt group (NH3 + “OOCR2); where x is equal to 0 to n-1, y and z can each independently be equal to o to n, provided that the sum of y and z is at least equal to 1 and the sum of x, y and z 20 is equal to or less than n, wherein Rx and R2 are each independently equal to an alkyl group having 1 to 100 carbon atoms. Rubber composition containing at least one rubber and a fatty acid-modified amine according to any one of claims 1-7. Rubber composition according to claim 8, characterized in that the rubber is a natural rubber. 1008677, - 20 - 4 Method for treating a rubber with a fatty acid modified amine, characterized in that a fatty acid modified amine according to any one of claims 1-8 is used. Use of a fatty acid-modified amine according to any one of claims 1-8 in a rubber composition. 12. Fatty acid-modified amine, rubber composition and method, as described and illustrated by the examples. i 1008677 COOPERATION TREATY (PCT) REPORT ON NEWNESS RESEARCH OF INTERNATIONAL TYPE __—--—— -1 ID IDENTIFICATION OF THE NATIONAL APPLICATION Characteristic of the applicant o (of the application 9031NL Dutch application no. DSM NV Date of request for a survey of the sew-in sew type Ooor Insanae for the Sew-in Sewing Research (ISA) has been granted the request for a research of the interna »sewn type no. SN 31001 NL I. CLASSIFICATION OF THE SUBJECT (in case of different classifications , indicate all dassificane symbols) According to the Interna sonata dassiiieaae (IPC) Int.Cl.6: C 08 K 5/20, C 08 L 21/00, C 08 G 73/02, C 08 K 5/17 II. FROM THE TECHNIQUE _ False minimum documentation Classification system _ Classification classifications _; _ Int.Cl.6: C 08 K, C 08 L, C 08 G Examined a cere aocumentaoe than the minimum documents »insofar as Such documents in the areas investigated & included lil.! 'NO RESEARCH AVAILABLE FOR CERTAIN CONCLUSIONS (oomerxmgen op supplementolad) | IV.1_1 LACK OF UNITY OF INVENTION (OmenKingen cc Supplemental Incsdad)! '--- - -------- - - -, -} if Form PCT.; Sa.'20 Ka i CS: S5a