Abstract:
N-methylolated/methoxymethylated aryldisulfonamides useful as rubber crosslinking agents are provided of the general formula: ##STR1## wherein x is between about 1 and 2, and y is between about 1 and 3, z is between about 0 and 1.5, the total of x, y and z being about 4.

Description:
BACKGROUND OF THE INVENTION 
     This invention is directed to methylolated/methoxymethylated disulfonamides which can be easily prepared and which are useful as crosslinking agents in rubber compositions containing a resorcinol resin or resorcinol. 
     Methylolated sulfonamides of various types are known. For example, U.S. Pat. No. 3,617,190 to Tesoro is representative. In example 2, methane sulfonamide was converted to the N,N-dimethylol derivative by reaction with 37% aqueous formaldehyde. The mixture was reacted for six hours, allowed to stand for 70 hours and then the product recovered by a rather complex procedure. The present invention provides novel disulfonamides by a simple and inexpensive procedure. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The novel disulfonamides of the invention are represented by the following general formula: ##STR2## wherein x is between about 1 and 2, and y is between about 1 and 3, z is between about 0 and 1.5, the total of x, y and z being about 4. Typical aryl include benzene, diphenyl ether, naphthalene and the like. 
     The novel process for preparing these compounds comprises reacting a mixture of from about 2 to 100 moles of methanol, an aryldisulfonamide and 3 to 5 moles of a formaldehyde donor per mole of aryldisulfonamide in the presence of a basic ion-exchange resin, and recovering the resultant product. Typical formaldehyde donors include formaldehyde, methyl formcel, and paraformaldehyde. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As illustrated by the above formula, the novel disulfonamides may have a minor amount of H bonded to the N where x and y does not equal 4. Mixed numbers, fractions and whole integers are all represented by x, y and z. Further, both x&#39;s or y&#39;s need not be the same but they usually are. 
     The compounds are conveniently prepared using excess methanol as the solvent (a co-solvent, such as water or acetone, can be used) at a temperature between about 40° C. and about 100° C. in a few hours with a catalytic amount of a basic ion-exchange resin. Typical ion-exchange resins include Rexyn 201, Rexyn R205, Amberlite IRA-400, and Dowex 21K in the hydroxide form. The product can then be recovered by evaporating the solvent, if employed. 
     The following examples will serve to illustrate preferred embodiments of the invention. All parts and percentages in said examples and elsewhere in the specification and claims are by weight unless otherwise indicated. 
     EXAMPLE 1 
     A mixture of 1200 ml of methanol, 118 g. (0.5 m.) of m-benzenedisulfonamide, 63 g. (2.0 m.) of powdered paraformaldehyde (95%) and 30 g of Rexyn 201 OH form ion-exchange resin (sold by Fisher Scientific Co.) was agitated and heated under a reflux condenser in a 2-1., round-bottom flask to 50° C. over a one hour period. Water (10 ml) was then added for the purpose of improving the solubility of the reagent; the mixture was heated to 60° C. and maintained at that temperature for two hours. The product was then recovered by filtration to yield a wet cake (wet resin) of 50.9 g. The filtrate was stripped of methanol on a Buchler rotating evaporater to final conditions of about 60° C./50 Torr to provide 158.3 g. of a viscous, oily product. By IR and NMR analysis, the product was indicated to have the following structure. ##STR3## 
     EXAMPLE 2 
     In order to vary the proportion of methylol and methoxymethyl groups, 74.2 g. of methyl formcel (55% CH 2  O in methanol; pH 7.0) was used as the formaldehyde source. The other ingredients were methanol (775 ml.), m-benzenedisulfonamide (76.4 g.), and Rexyn R 205 (32.5 g.). The mixture was agitated and heated under a reflux condenser in a 2-1., round-bottom flask to 50° C. over a 40-minute period, maintained at 50° C. for one hour, heated to 65° C. over a 20-minute period and finally maintained at 65° C. for two hours. The mixture was filtered hot to provide 33.5 g. of wet resin catalyst. The filtrate was evaporated on a Buchler rotary evaporator to 72° C. (pot)/125 Torr to provide 145.5 g. of a sticky, solid product identified by IR and NMR analyses as having the following structure: ##STR4## 
     EXAMPLES 3-5 
     Following the general procedure of Examples 1 and 2, compounds were prepared having the following ratios: 
     
         ______________________________________Reinforcing agent         N--CH.sub.2 --O--CH.sub.3                       N--CH.sub.2 OH______________________________________Ex 3.         1.8           0.8Ex 4.         1.4           1.9Ex 5.         1.0           1.8______________________________________ 
    
     The compounds can be prepared in a dry-product form by adding silica (e.g., PPG Industries Hi-Sil 215) to the solution before stripping of the solvent. 
     EXAMPLES 6-11 
     The products from Examples 1-5 or a commercial crosslinking agent (Cyrez 963 crosslinking agent) and a control were each formulated into rubber compositions. For each product evaluation a masterbatch base rubber composition containing Penacolite Resin B-18-S and no crosslinking agent was mixed and split into two 700 gram batches. Cyrez 963 crosslinking agent liquid was incorporated into one batch and one of the compounds of the invention of Examples 1 to 5 incorporated into the other. The rubber composition formulation is shown in the following Table I: 
     
                       TABLE I______________________________________STANDARD NATURAL SYNTHETIC RUBBERFORMULATIONMaterials                    phr______________________________________Natural Rubber               46.5SBR-1500 (Goodrich rubber)   38.5Polybutadiene                15.0N-550 (FEF) Black            45.0Hi-Sil 233 (PPG Industries silica)                        15.0Stearic Acid                  1.5Flectol H (Monsanto Co. antioxidant)                         2.0Sunthene 3125 (Sun Oil Co. process oil)                         5.0Zinc Oxide                    3.0Sulfur                        3.0Santocure NS (Monsanto Co. accelerator)                         1.2Penacolite Resin B-18-S (Koppers Co.)                         3.85Cyrez 963 (American Cyanamid Co. cross linking agent)                         2.75Methylolated/methoxymethylated                         3.76.sup.(1)m-benzenedisulfonamide______________________________________ .sup.(1) Calculated on an &#34;equivalent weight&#34; basis with Cyrez 963; that is; 2.75 g of Cyrez 963 has the same methoxy group functionality as 3.76 of methylolated/methoxymethylated mbenzenedisulfonamide. 
    
     The above ingredients, with the exception of the sulfur and reinforcing agents, were mixed for 10 minutes in a Banbury mixer, the temperature rising to 320° F. during this period. The remaining materials were added when the masterbatch rubber was being milled on a rubber mill at a temperature of 180° F. Two wire pull-out test pads (ASTM D-2229) were made from each compound with 1×5×0.25 mm brass plated steel cord. The pads were vulcanized to their optimum cure. 
     The pads were tested by cutting them in half (seven wires in each pad) and subjecting two of the halves to aging for 48 hours at 250° F. while holding back their mating halves as room temperature controls. 
     In Table II, rheometer data shows that the induction time (time to 5-point rise) for the invention compounds is comparable to the commercial material. 
     
                       TABLE II______________________________________RHEOMETER DATA.sup.(1) OF COMPOUNDS CONTAININGMETHYLOLATED/METHOXYMETHYLATED m-BENZENEDISULFONAMIDES                                         Cy-Cross-Linking       Con-                              rezAgent       trol   Ex 1   Ex 2 Ex 3 Ex 4 Ex 5 963______________________________________Maximum Torque,.sup.(2)       40.8   52.4   51.2 51.8 52.7 47.1 52.0M.sub.HMinimum Torque,       10.6   12.8   12.1 12.8 12.0 10.2  9.9M.sub.H90% Maximum 37.8   48.4   47.3 47.9 48.7 43.4 47.8Torque, .9M.sub.H5-Point Rise, M.sub.5       15.6   17.8   17.1 17.8 18.0 15.2 14.9Time.sup.(3) to M.sub.5       12.6    9.8   11.1  9.5 10.0 10.3 10.0Time to .9M.sub.H       17.6   13.5   47.5 32.6 35.0 38.0 43.0Cure Time   22.6   36.5   52.5 37.6 40.0 43.0 48.0______________________________________ .sup.(1) Monsanto Rheometer 100; 1.66 HZ, ± 1° Arc; 300° F.; type MPC (microproduction control) dies .sup.(2) Rheometer Torque Units .sup.(3) Minutes 
    
     In Table III, adhesion data is presented which shows that the invention compounds are comparable to the commercial material in reinforcing effectiveness. 
     
                                           TABLE III__________________________________________________________________________ADHESION STUDIES OF VARIOUS METHYLOLATED/METHOXYLATEDm-BENZENEDISULFONAMIDE CROSS-LINKING AGENTS.sup.(1)   48 hrs. @ 250° F.                     72 hrs. @ 185° F.; 100% R.H.   R.T. Control          Aged % Change                     R.T. Control                            Aged % Change__________________________________________________________________________BW-29 Wire.sup.(2)Control  36( 0)          35( 40)                -3    34( 10)                            72( 50)                                 +112Ex 1    117(100)          44(100)               -62   122( 95)                            95( 75)                                 -22Ex 2    105( 95)          45(100)               -57   107(100)                            92( 95)                                 -14Ex 3    115( 95)          46(100)               -60   117( 90)                            97( 85)                                 -17Ex 4    110(100)          46( 95)               -58   121(100)                            87( 80)                                 -28Ex 5    123(100)          47(100)               -62   122(100)                            94( 80)                                 -23Cyrez 963   127(100)          48(100)               -62   133(100)                            106( 90)                                 -20BW-33 Wire.sup.(3)Control  31( 5)          26( 25)               -16    24( 5)                            46( 10)                                 +92Ex 1     76( 75)          35( 60)               -54    76( 75)                            60( 60)                                 -21Ex 2     89( 65)          37( 70)               -58     87( 75)                            79( 85)                                  -9Ex 3     84( 50)          35( 50)               -58    82( 50)                            65( 50)                                 -21Ex 4     87( 65)          38( 50)               -56    84( 75)                            72( 60)                                 -14Ex 5     86( 70)          37( 75)               -57    85( 80)                            69( 50)                                 -19Cyrez 963   102( 75)          44( 75)               -57    86( 70)                            82( 50)                                  -5BW-23 Wire.sup.(4)Control 115( 20)          99( 85)               -14   118( 20)                            165( 85)                                 +40Ex 1    266(100)          104(100)               -61   256(100)                            225( 75)                                 -12Ex 2    258(100)          118(100)               -54   258(100)                            252(100)                                  -2Ex 3    264( 95)          121(100)               -54   253( 95)                            222( 80)                                 -12Ex 4    259( 95)          121( 95)               -53   256( 95)                            236( 85)                                  -8Ex 5    273(100)          123(100)               -55   264( 95)                            245( 80)                                  -7Cyrez 963   289(100)          138(100)               -52   287(100)                            256( 95)                                 -11__________________________________________________________________________ .sup.(1) The first number is pull out force in pounds; the second number (in parenthesis) is % Rubber Coverage .sup.(2) ASTM D2229  1/2&#34; embedment 1 × 5 × 0.25 mm (Bekeart) .sup.(3) ASTM D2229  1/2&#34; embedment 1 × 5 × 0.25 mm (Enka) .sup.(4) ASTM D2229  1&#34; embedment 1 × 3 + 5 × 7 × 0.15 mm (Bekeart) 
    
     While the above examples are illustrative of the invention, obvious modifications and variations may occur to one skilled in the art. Accordingly the invention is intended to be limited only by the appended claims.