FR2494705A1 - POLYMER (POLYSULFIDE) RUBBER TREATING COMPOSITIONS AND RUBBER MIXING METHOD - Google Patents

Abstract

THE INVENTION RELATES TO A POLY RUBBER TREATMENT COMPOSITION (POLYSULFIDE). ACCORDING TO THE INVENTION, IT CONTAINS A POLYMERIC COMPOUND OF THE FORMULA (CF DRAWING IN BOPI) IN WHICH: N IS BETWEEN 1.5 AND 4, M IS BETWEEN 3 AND 200, R IS AN ALIPHATIC DIVALENT RADICAL IN ORDER FROM 2 TO 10 CARBON ATOMS, THIS RADICAL MAY POSSIBLY INCLUDE ONE OR MORE ETHER LINKS; AND A AND B ARE INDIVIDUALLY MERCAPTO, MERCAPTOALCOYL, MERCAPTOALCOXYALCOYL, HYDROXYALCOYL, HYDROXY OR HYDROXYALCOXYALCOYL. THE INVENTION APPLIES IN PARTICULAR TO THE RUBBER INDUSTRY.

Description

The raw natural rubber generally has a fairly high viscosity and

  therefore, it does not mix easily and quickly with the many additives used during its treatment. To facilitate the addition of these additives, the rubber is usually softened by

  submitting to a preliminary stage called chewing.

  During mastication, the rubber is placed in a mixer such as the Banbury mixer, and is subjected to heat and possibly to a peptizing agent,

  for example, such as dixylyl disulfide, pentachloro

  phenyl disulfide or dibenzamido-diphenyldisulfide while being mixed for several minutes. The resulting mixture is then discharged, put on a sheet on a rolling mill, and cooled. The softened rubber is then

  mixed with the necessary ingredients.

  Although somewhat effective in the treatment of rubber, these traditional methods have a number of inherent disadvantages. For example, traditional peptizing agents can not be mixed together during the chewing step, resulting in a multi-step process. The need for a separate chewing stage greatly increases the energy consumption, time and cost of the process, and also the complexity of the equipment required for implementation

of the process.

  In addition, because of their relatively low disulfide content, the peptizing agents according to the prior art are also often very inefficient. The inefficiency first results in an increase in mixing times and mixing temperatures which, in turn, results in inconsistent mixing results, a decrease in the mixing equipment capacity and an increase in the hazard. of prevulcanization of the rubber during its mixing. As another result,

  physical properties of rubber, as well as its characteristics

  flow, mixing and extrusion ticks are

affected adversely.

  When traditional peptizing agents react with rubber, the resulting byproduct is often a molecular weight mercaptan. This by-product affects

  adversely affect the physical properties of the rubber.

  It is therefore necessary to find a treatment composition and a process for using such a composition to avoid the disadvantages associated with traditional rubber processing. It is therefore an object of the present invention to provide a rubber treatment composition and a process for using the composition for the treatment of rubber compositions eliminating the need for a separate chewing step, thereby allowing the chewing and mixing steps to take place. to be combined into one

continuous operation.

  It is another object of the present invention to provide a composition and process for mixing natural and synthetic rubbers, allowing for shorter mixing times, lower energy use, lower mixing and deposition temperatures, giving better flow and physical properties, better mixing and extrusion characteristics and better physical characteristics of this

rubber.

  It is another object of the present invention to provide novel rubber treatment compositions which facilitate mixing of the rubber compounds with natural and synthetic rubbers with respect to the weather conditions, arranging the scale for the addition of the various ingredients of the rubber. mixing and the possibility of uninterrupted work with the compound compound through lower and safer deposit temperatures without adversely affecting the physical properties of these rubber compounds. Other objects and advantages of the invention will become more apparent

  upon reading the following description.

  According to the invention, it has now been found that these and other objectives can be achieved by using a blending agent of a poly (disulfide) or poly (polysulfide) aliphatic compound in an amount sufficient to break the rubber. natural or synthetic. Such compounds are often called

  "aliphatic polymeric di- or polysulfides".

  An essential component of the composition of

  according to the invention is a compound of poly (di-

  sulfide) or aliphatic poly (polysulfide) which produces a polymeric residue upon reaction with the rubber, and o the weight ratio of carbon to sulfur is between about 1.9 to 1 and about 0.19 to 1. Such compounds can be represented by the formula: A Sn-R-mB wherein: n is between 1.5 and 4; m is from 3 to 200; R is a divalent aliphatic radical of the order of 2 to 10 carbon atoms and optionally one or more ether linkages, or a small proportion of the R groups may be trivalent; A and B are individually mercapto, mercaptoalkyl, mercaptoalkoxyalkyl, hydroxy, hydroxyalkyl or hydroxyalkoxyalkyl. In a mode of

  preferred embodiment of the invention,

  n is between 1.9 and 2.1 m is between 3 and 30 R is an alkylene moiety having on the order of 2 to 6 carbon atoms such as, for example, ethylene, propylene, propylene, hexamethylene, 1,1-dimethylethylene, and the like; or an alkylene moiety having up to about two ether bonds, such as ethyleneoxyethylene, ethyleneoxymethyleneoxyethylene, and the like; and A and B are individually mercapto or mercaptoalkoxyalkyl. Examples of compounds within the scope of the above formula are poly (dithioethylene), poly (tetrathioethylene), poly (trithiohexamethylene),

  poly (oxyethylenedithioethylene), poly (oxymethyleneoxy)

  ethylenedithioethylene), and the like. Poly (polysulfide) compounds useful in carrying out the present invention can be obtained from commercial sources, or prepared according to known methods. For example, such compounds can be prepared according to the preparation methods described in "Vanderbilt Rubber Handbook",

  R. T. Vanderbilt Company, 1978 edition, pages 201-8.

  In addition to the essential component, the treatment composition according to the invention contains other optional ingredients for converting the polysulfide to a more suitable form such as a powder or paste, or to facilitate the introduction of the composition into the natural rubber or synthetic. Such an ingredient can

  be a finely divided inorganic absorbent.

  The term "mineral absorbing agent" used in the

  present description, indicates any mineral substance

  particulate inorganic material on the outer surface of

  which can be absorbed the composition of poly (poly-

  sulfide). Examples of such substances include

  natural and synthetic clays.

  As is known, mineral clays are hydrated silicates of aluminum, iron or magnesium and may contain other mineral particles. The typical natural clays that can be used according to the invention are kaolinite, montmorillonite, illite, clorite and attapulgite, and include china clay, kaolin clay, plastic clay, clay refractory, flint clay, diaspore clay, mullite, bentonite and the like. Synthetic silica and silicate clay materials as well as diatomite can also be used. For example, synthetic molecular sieves such as 13A molecular sieves may be employed if desired. The mesh dimension

249470S

  particulate absorbent mineral for use according to the invention is not critical. The mesh size is generally between 80 and 400+, with a preferred size of 100 mesh or less, according to the American standard. Other materials which may be mentioned include hydrocarbons, hydroxy ether compounds, with alcoholic and glycolic hydroxyl groups,

  sulfonamides, waxes and paraffins. More specifically

  firstly, these additional materials may comprise: (a) from 0% to about 20% of selected sulfonamides

  in the group of N-alkyl derivatives of aryl

  sulfonic; (b) in the range of 0% to about 20% of compounds selected from the group consisting of alkylphenoxy ethers of ethylene glycols or polyglycols wherein the alkyl group contains from about 6 to about 12 carbon atoms and the group polyglycol contains from about 2 to about 6 oxyethylene groups; (c) from about 0% to about 20% of waxes of animal or vegetable origin; and

  (d) from about 0% to about 20% hydro-

  carbides selected from the group consisting of

mineral and mineral waxes.

  Examples that may be mentioned are the sulfonamides indicated in (a), N-ethyl-ptoluenesulphonamide,

  N-methylbenzenesulfonamide, and N-butyl-2,4-xylene-

  sulfonamide. As hydroxy ethers typical of (b) above may be mentioned that can be used in the compositions according to the invention, octylphenoxyhexaethylene glycol, dodecylphenoxytriethylene glycol, nonylphenoxytetraethylene

  glycol and nonylphenoxydiethylene glycol.

  Among the waxes indicated in (c) above, mention may be made of carnauba wax, lanolin and oil

of jujube.

  Examples of the hydrocarbons indicated in (b), petrolatum, mineral oil and

paraffin wax.

  It should be noted that the compositions according to the invention

  are not limited to additional or additional materials above and that any similar chemical will suffice. All ingredients can be of technical quality and may contain quantities

  variables of related materials, by-products and others.

  The weight ratios of the optional additives are not critical and depend on such factors as the compatibility of the individual additives, the desires of the formulator, the availability of the individual additives and other factors that will be apparent to those who are

  competent in the art of mixing elastomers.

  A preferred formulation for balanced processing aids according to the invention contains the following approximate weight percentages of compounds which are typical of their class: (a) 100% to 25% of a poly (polysulfide) compound of formula A4Sn-R .mSn-A

  o A, R, n and m are as defined above

above; (b) 0% to 15% lanolin;

  (c) 0% to 15% of tetraethylene glycol mononomyl

  phenol ether; (d) 0% to 15% petrolatum;

  (e) 0% to 65% absorbent mineral.

  The compositions according to the invention are generally

  added to the rubber at the beginning of the mixing cycle.

  The usual additives, such as pigments, fillers, vulcanizing agents and others, can then be added and

  all the mixture to be accomplished in one operation.

  The processing aid according to the invention is employed in small but effective amounts. It is generally added so that the amount of the poly (polysulfide) is from about 0.2% to about 5% and preferably from about 0.5% to about 1.5%, and the total weight of the composition ( all components) is from about 0.2 to about 10, preferably from about 0.5 to 3, all being weight percentages based on the total weight of

rubber material.

  The processing aids according to the invention can be used for mixing any type of natural or synthetic rubber or mixtures thereof. Suitable rubbers which may be used with the breaking agent according to the invention are natural rubbers, styrene-butadiene rubber, ethylene-propylene rubber, butadiene rubber, butadiene rubber and the like. acrylonitrile, epichlorohydrin rubber, acrylic rubber, neoprene rubber, chloroprene rubber, butyl rubber, block polymers of styrene and butadiene, and synthetic and natural rubber analogues. The

  rubber can be virgin or regenerated.

  The following examples are presented to better describe the present invention as well as its advantages.

EXAMPLE I

  The rubber compositions of Table I were prepared by mixing the various ingredients in an internal mixer in the conventional manner. The sulfur and the accelerator of the composition 2 could not be added to the mixer because of the high temperatures, and were therefore added in a second step

on a two-roll mill.

  After deposition, the compositions were cured in a

  mold of 15.24 x 15.24 x 0.254 cm and various

  Physical data were evaluated.

TABLE I

  Ingredients Composition No1 Composition No2 Smoked flakes N 4, 0 parts, 0 parts Carbon black N-110 Pine tar Stearic acid Zinc oxide Disulfide polymer *

N-cyclohexyl-2-

  Benzothiozolesulfenamide Sulfur, 0 4.5 4.5 4.5, 0 4.5 4.5 4.5 1.62 0.5 2, 6 0.5 2.6 * The disulfide polymer had the approximate structure HS ( C2H40CH20C2H4SS) 5C2H40CH202H4SH o a fractional number of units in parentheses is trivalent. The data of these experiments are summarized in Table II as follows:

TABLE II

  Composition and Results Properties 1 2 Mixing Time (minutes) 9 14 Product Temperature at Deposition (OC) 124 157 Final Amperage Draw 43 68 Pre-Cured at 160WC (minutes) 10 6% cured at 1600C (minutes) 14 9 Viscosity ( ML4 to 1000C) 54 70 Dispersion quality very good average Single pass capacity yes no Tensile strength (105 Pa) 296 289.5 300% (105 Pa) module 138 136,5 Elongation (%) 580 530 Hardness (Shore A) 67 64 Tear resistance matrix C (105 Pa) 14.82 14.48 As is apparent from the data of the

  Table II, the use of the composition according to the invention

  This allows faster mixing, requires less power, and breaks the rubber at a much lower Mooney viscosity. The data also show that the physical properties of the cured product are also good

  or better than those of the witness where the new

was not used.

EXAMPLE II

  The synthetic rubber compositions shown in Table III were prepared in an internal mixer. For composition 4, the sulfur and accelerator could not be added to the mixer due to the high temperature, and were therefore added to a two-roll mill at a second stage. The compositions were hardened and evaluated as

in example I.

TABLE III

  Composition Composition Ingredient N 3 NI 4 SBR Type 1500 100.0 100.0 Carbon Black N-100 50.0 50.0 Zinc Oxide 2.5 2.5 Naphthalene Oil 10.0 10.0 Zinc Laurate 1, 5 1.5

Polymer of disulfide * 1,67 -

N-tert-butyl-2-

  Benzothiozolesulfenamide 1.25 1.25 Sulfur 1.75 1.75 * As in Example I.

  SBR: styrene-butadiene rubber.

  The data from these experiments are summarized in Table IV as follows: I1

TABLE IV

  Properties Composition and results

3 -4

  Mixing time (minutes) 8 13 Deposition product temperature (OC) 121 151, 5 Final amperage draw 57 70 Prepulverisation at 1600C (minutes) 6 5% hardening at 1600C (minutes) 11 12 Viscosity (ML4 at 1000C) 55 69 Dispersion quality very good average Single pass capacity yes no Tensile strength (105 Pa) 233 233.7 300% modulus (10i Pa) 109 110.3 Elongation (%) 540 550 Hardness (Shore) A) 55 58 Tear resistance, matrix C (105 Pa) 12.75 13.79 As is apparent from Table IV, the use of the composition according to the invention allows significant decreases in mixing times and deposition temperatures, and offers other beneficial effects when mixing a synthetic rubber. As is also apparent, these beneficial results are achieved without adversely affecting the characteristics of the

rubber.

EXAMPLE III

  Various embodiments of the invention containing an absorbent mineral have been prepared. These compositions have been used for use in the treatment of synthetic and natural rubbers. The resulting composition and percent weight of the various ingredients are shown in Table V.

TABLE V

Ingredient Compositions

A B C D E

  Non-reinforcing crushed clay Reinforced crushed clay Disulfide polymer * Lanolin Petrolatum N-ethyltoluenesulfonamide Nonylphenoxytetraethylene glycol

37 53 53 53 53

24.7 - - - -

24.3 42 42 42 42

- - 5

- - 5

- - - - 5

  As in Example 1N, five natural compositions 5, 6, 7, 8 and 9 were prepared using 1.62 parts of the products A, B, C, D and E, respectively, with the formula of Example I, Composition 1. The Control Composition

  was also prepared as in Example I, Composition 2.

  The mixing characteristics of these compositions are

Table VI.

Property

TABLE VI

  Natural rubber compositions and results

6 7

  Mixing time (minutes) Product temperature at the deposit (OC) Final amperage draw (OC) Viscosity (ML4 at 100WC)

8 9 10

9 8 11 11 10 14

118.4 112.7 121

124 121

57 30 52 52 49 68

48 63 60 60 70

  Quality of dispersion tb exc. tb

tb average tb

  only one pass capacity yes yes yes yes yes no

  tb = very good; exc. = excellent.

EXAMPLE VI

  Using procedures similar to those of Example II, formulas prepared five synthetic rubber compositions 11, 12, 13, 14 and employing the products A, B, C, D and E. An additional composition, the NI 16 control composition was prepared using the procedure of Example II, Composition 4. The blending characteristics of these

  compositions are summarized in Table VII.

TABLE VII

  Property Synthetic Rubber Compositions and Results Mix Time (minutes)

11 12 13

14 15 16

9 8 11 9 8 13

  Product temperature at run-off (C) Final amperage draw (C) Viscosity (ML4 at 100 C) Dispersion quality

118.5 to 114.4

57 42

49 48

tb exc.

121 121

121 151.5

51 52 52 70

61 60 55 69

tb tb tb medium-

  only one pass capacity yes yes yes yes yes no

tb = very good; exc. = excellent.

  As apparent from the foregoing, the compositions of the invention eliminate the need for a separate chewing operation, consuming less energy to break the rubber and mix all the ingredients. The present invention also provides better mixing times, better dispersion of additives and lower

  mixing temperatures when mixing rubber.

  In addition, the new compositions according to the invention allow the mastication and mixing steps to be combined in a continuous operation, because the mixing times are shorter and the

mixture are weaker.

Claims (16)

R E V E N D I C A T I 0 N S CLAIMS   1.- poly (polysulfide) rubber treatment composition, characterized in that it contains a polymeric compound having the formula A $ Sn-R mB wherein: n is between 1.5 and 4, m is between 3 and 200, R is a divalent aliphatic radical having from 2 to 10 carbon atoms, said radical possibly containing one or more ether linkages; and   A and B are individually mercapto, mercapto   alkyl, mercaptoalkoxyalkyl, hydroxyalkyl, hydroxy or hydroxyalkoxyalkyl.   2. Composition according to claim 1, characterized in that a small proportion of the radicals R is trivalent.   3. Composition according to claim 1, characterized in that n is between about 1.9 and about 2.1, m is between about 3 and about 30, R is an alkylene having from about 2 to about about 6 carbon atoms, said alkylene having up to two ether bonds, and A and B are individually mercapto or mercaptoalkoxyalkyl. 4. Composition according to claim 3, characterized in that R is chosen from the group consisting of ethylene, propylene and hexamethylene,   1,1-dimethylethylene, ethyleneoxyethylene, and ethylene-   oxyméthylèneoxyéthylène. 5. Composition according to claim 1, characterized in that the abovementioned polymeric compound is chosen from the group consisting of poly (dithioethylene), poly (tetrathioethylene), poly (trithiohexamethylene),   poly (oxyethylenedithioethylene) and poly (oxymethyleneoxy)   éthylènedithioéthylène). 6. Composition according to claim 1, characterized in that addition materials are added, comprising sulphonamides, compounds with   hydroxyether groups, waxes and hydrocarbons.   7. A composition according to claim 6, characterized in that said additional materials comprise: (a) from 0% to about 15% of one or more sulfonamides selected from the group consisting of N-alkyl derivatives of arylsulfonic acids; (b) in the range of 0% to about 15% of one or more hydroxy ether compounds selected from the group consisting of alkylphenoxy ethers of ethylene glycols or polyglycols wherein the alkyl group contains from about 6 to about 12 carbon atoms and the polyglycol group contains from about 2 to about 6 oxyethylene groups; (c) from about 0% to about 15% of one or more waxes selected from the group consisting of animal or vegetable waxes; and (d) from 0% to about 15% of one or more hydrocarbons selected from the group consisting of   in mineral oil and mineral waxes.   8. Composition according to claim 7, characterized in that the abovementioned sulfonamide is chosen from the group consisting of N-ethyl-ptoluenesulphonamide,   N-methylbenzenesulfonamide, and N-butyl-2,4-xylenesulphonamide mide.   9. Composition according to claim 7, characterized in that the abovementioned hydroxyether is chosen from the group consisting of octylphenoxyhexaethylene   glycol, dodecylphenoxytriethylene glycol, nonylphenoxy   tetraethylene glycol and nonylphenoxydiethylene glycol.   10. Composition according to claim 7, characterized in that the abovementioned waxes are chosen from the group consisting of Carnauba wax, lanolin and jujube oil.   11. Composition according to claim 7, characterized in that the abovementioned hydrocarbons are chosen from the group consisting of petrolatum, oil and mineral and paraffin wax.   12. A rubber treatment composition, characterized in that it contains a particulate absorbent material, with, absorbed on its surface, a rubber treatment composition according to any one of preceding claims.   13. A rubber composition comprising a base of natural or synthetic rubber and rubber additives, characterized in that it contains a small but effective amount of a rubber treatment composition according to any one of Claims 1 to 11.   14. The composition of claim 13, characterized in that the amount of the rubber treatment composition is between about 0.2 and 3% by weight based on the total weight of said composition. 15. A process for mixing rubber of the type consisting of mixing rubber with additives of the class consisting of pigments, fillers and vulcanizing agents, characterized in that it consists in mixing a small but effective amount of a composition of rubber treatment according to any one of   1 to 11 with the rubber, at the beginning of   mixing cycle before chewing said rubber.   16. A process according to claim 15, characterized in that the amount of said rubber treatment auxiliary is between about 0.2% and about 3%.