Patent Publication Number: US-7709559-B1

Title: Cure accelerators for anaerobic curable compositions

Description:
RELATED U.S. APPLICATION DATA 
     This application continues in part from U.S. patent application Ser. No. 11/072,420, filed Mar. 7, 2005, now U.S. Pat. No. 7,411,009, which in turn continues in part from U.S. patent application Ser. No. 10/157,804, filed May 31, 2002 (now U.S. Pat. No. 6,958,368 issued Oct. 25, 2005), the entire disclosure of each of which is hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to new cure accelerators for anaerobic curable compositions. These anaerobic cure accelerators are generally sulfonimide derivatives and sulfonamide derivatives. 
     2. Brief Description Of Related Technology 
     Anaerobic adhesive compositions generally are well-known. See e.g., R. D. Rich, “Anaerobic Adhesives” in  Handbook of Adhesive Technology,  29, 467-79, A. Pizzi and K. L. Mittal, eds., Marcel Dekker, Inc., New York (1994), and references cited therein. Their uses are legion and new applications continue to be developed. 
     Conventional anaerobic adhesives ordinarily include a free-radically polymerizable acrylate ester monomer, together with a peroxy initiator and an inhibitor component. Oftentimes, such anaerobic adhesive compositions also contain accelerator components to increase the speed with which the composition cures. 
     Desirable anaerobic cure-inducing compositions to induce and accelerate cure may include saccharin, toluidines, such as N,N-diethyl-p-toluidine (“DE-p-T”) and N,N-dimethyl-o-toluidine (“DM-o-T”), acetyl phenylhydrazine (“APH”), maleic acid (“MA”), and quinones, such as napthaguinone and anthraquinone. See e.g., U.S. Pat. Nos. 3,218,305 (Krieble), 4,180,640 (Melody), 4,287,330 (Rich) and 4,321,349 (Rich). 
     Saccharin and APH have been used as standard cure accelerator components in anaerobic adhesive cure systems since the inception of the technology, and has been well studied in that connection. Hitherto, it was believed that the nitrogen-hydrogen bond off the heterocycle ring was necessary to achieve performance under anaerobic conditions, as early studies substituting the hydrogen with an alkyl group proved to be ineffective. See F. J. Boerio et al., “Surface-Enhanced Raman Scattering from Model Acrylic Adhesive Systems”,  Langmuir,  6, 721-27 (1990), in which it is stated “[t]hese salts [of saccharin] are thought to be important factors in the curing reaction of the adhesive.” 
     And while anaerobic curable compositions having cure components including saccharin, DE-p-T and cumene hydroperoxide (“CHP”) display good performance on metal substrates, such compositions do not display as impressive performance on glass substrates. Thus, there exists a specific need to tailor anaerobic curable compositions to perform well on such substrates. 
     Recently, Henkel Corporation was granted U.S. Pat. No. 6,835,762 (Klemarczyk), which defines an invention directed to an anaerobic curable composition, comprising:
         (a) a (meth)acrylate component;   (b) an anaerobic cure-inducing composition; and   (c) an anaerobic cure accelerator compound having the linkage —C(═O)—NH—NH— and an organic acid group on the same molecule. The composition is substantially free of acetyl phenyl hydrazine and maleic acid, and the anaerobic cure accelerator compound excludes 1-(2-carboxyacryloyl)-2-phenylhydrazine.       

     And Henkel Corporation was granted U.S. Pat. No. 6,835,762 described as an anaerobic curable composition, comprising: (a) a (meth; acrylate component; (b) an anaerobic cure-inducing composition and (c) an anaerobic cure accelerator compound having the linkage —C(═O)—NH—NH— and an organic acid group on the same molecule, provided the anaerobic cure accelerator compound excludes 1-(2-carboxyacryloyl)-2-phenylhydrazine wherein the anaerobic curable composition is substantially free of acetyl phenyl hydrazine and maleic acid. 
     There continues to be an on-going desire to find alternative technologies for accelerating the cure of anaerobic curable compositions, to differentiate existing products and provide supply assurances in the event of shortages or cessation of supply of raw materials. Accordingly, it would be desirable to identify new materials, which function as accelerators in the cure of anaerobic curable compositions. 
     SUMMARY OF THE INVENTION 
     The present invention provides new cure accelerators for anaerobic curable compositions. The anaerobic curable compositions are typically used as adhesives or sealants. 
     The anaerobic cure accelerators are saccharin derivatives within structure I 
                         
where R and R 1  may or may not be present, but when at least one is present it is ═O; X is N or S; and R 2  is halogen or a Group I element, which may be in hydrated form.
 
     The addition of these materials into anaerobic curable compositions as a replacement for some or all of the amount of conventional anaerobic cure accelerators [such as o-benzoic sulfimide or saccharin, used interchangeably throughout, and cumene hydroperoxide (“CHP”)] surprisingly provides at least comparable cure speeds and physical properties for the reaction products formed therefrom. 
     This invention also provides anaerobic curable compositions and anaerobic curable composition systems prepared with such cure accelerators, methods of preparing and using the inventive anaerobic curable compositions as well as reaction products of the inventive anaerobic curable compositions. 
     The present invention will be more fully appreciated by a reading of the “Detailed Description of the Invention”, and the illustrative examples which follow thereafter. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIGS. 1A and 1B  depict a bar chart of breakloose torque and 180° prevail torque versus fixture time on threaded steel fasteners for anaerobic curable compositions, with and without saccharin and with and without CHP, for NOS or SBS, and as presented in Table 3. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides anaerobic cure accelerators, which are generally sulfinimide derivatives and sulfonimide derivatives. The addition of such compounds as cure accelerators into anaerobic curable compositions as a replacement for some or all of the amount of conventional cure accelerators, namely saccharin and/or CHP, surprisingly provides at least comparable cure speeds and physical properties for the reaction products formed. 
     The inventive cure accelerators may be within structure I 
                         
where R and R 1  may or may not be present, but when at least one is present it is ═O; X is N or S; and R 2  is halogen or a Group I element, which may be in hydrated form. More specifically, R and R 1  should be present and are S═O; X is N; and R 2  is chlorine, sodium or its hydrated form.
 
     Saccharin is o-benzoic sulfimide. The N-chloro derivative thereof is shown as structure II, N-chloro saccharin (“NCS”); the N-sodium derivative thereof is shown as structure III, o-benzoic sulfimide sodium salt (“SBS”). The hydrated form of o-benzoic sulfimide sodium salt is shown as structure IV. 
     These saccharin derivatives are useful in, or as primers for use with, anaerobic curable compositions as a replacement for some of or all of the saccharin typically used as an accelerator. The saccharin derivatives display good solubility, stability and anaerobic activity in anaerobic curable compositions. 
     It is also desirable to include in combination various species within the genus of structure I. For instance, structures II and III and II and IV in combination provide improved solubility in a (meth)acrylate component and improved performance over either individually. 
     Anaerobic curable compositions generally are based on a (meth)acrylate component, together with an anaerobic cure-inducing composition. In the present invention, such anaerobic curable compositions are desirably substantially free of saccharin and include the inventive cure accelerators within structure I. 
     (Meth)acrylate monomers suitable for use as the (meth)acrylate component in the present invention may be chosen from a wide variety of materials, such as these represented by H 2 C═CGCO 2 R 1 , where G may be hydrogen, halogen or alkyl groups having from 1 to about 4 carbon atoms, and R 1  may be selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, aralkyl or aryl groups having from 1 to about 16 carbon atoms, any of which may be optionally substituted or interrupted as the case may be with silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbonate, amine, amide, sulfur, sulfonate, sulfone and the like. 
     Additional (meth)acrylate monomers suitable for use herein include polyfunctional (meth)acrylate monomers, such as, but not limited to, di- or tri-functional (meth)acrylates like polyethylene glycol di(meth)acrylates, tetrahydrofuran (meth)acrylates and di(meth)acrylates, hydroxypropyl (meth)acrylate (“HPMA”), hexanediol di(meth)acrylate, trimethylol propane tri(meth)acrylate (“TMPTMA”), diethylene glycol dimethacrylate, methylene glycol dimethacrylate (“TRIEGMA”), tetraethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, di-(pentamethylene glycol) dimethacrylate, tetraethylene diglycol diacrylate, diglycerol tetramethacrylate, tetramethylene dimethacrylate, ethylene dimethacrylate, neopentyl glycol diacrylate, trimethylol propane triacrylate and bisphenol-A mono and di(meth)acrylates, such as ethoxylated bisphenol-A (meth)acrylate (“EBIPMA”), and bisphenol-F mono and di(meth)acrylates, such as ethoxylated bisphenol-F (meth)acrylate. 
     Still other (meth)acrylate monomers that may be used herein include silicone (meth)acrylate moieties (“SiMA”), such as those taught by and claimed in U.S. Pat. No. 5,605,999 (Chu), the disclosure of which is hereby expressly incorporated herein by reference. 
     Of course, combinations of these (meth)acrylate monomers may also be used. 
     The (meth)acrylate component should comprise from about 10 to about 90 percent by weight of the composition, such as about 60 to about 90 percent by weight, based on the total weight of the composition. 
     Recently, additional components have been included in traditional anaerobic curable compositions to alter the physical properties of either the curable compositions or the reaction products thereof. 
     For instance, one or more of maleimide components, thermal resistance-conferring coreactants, diluent components reactive at elevated temperature conditions, mono- or poly-hydroxyalkanes, polymeric plasticizers, and chelators (see International Patent Application No. PCT/US98/13704, the disclosure of which is hereby expressly incorporated herein by reference) may be included to modify the physical property and/or cure profile of the formulation and/or the strength or temperature resistance of the cured adhesive. 
     When used, the maleimide, coreactant, reactive diluent, plasticizer, and/or mono- or poly-hydroxyalkanes, may be present in an amount within the range of about 1 percent to about 30 percent by weight, based on the total weight of the composition. 
     The inventive compositions may also include other conventional components, such as free radical initiators, other free radical co-accelerators, inhibitors of free radical generation, as well as metal catalysts, such as iron and copper. 
     A number of well-known initiators of free radical polymerization are typically incorporated into the inventive compositions including, without limitation, hydroperoxides, such as CHP, para-menthane hydroperoxide, t-butyl hydroperoxide (“TBH”) and t-butyl perbenzoate. Other peroxides include benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide, butyl 4-bis(t-butylperoxy)valerate, p-chlorobenzoyl peroxide, cumene hydroperoxide, t-butyl cumyl peroxide, butyl perbenzoate, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di-t-butyl-peroxyhex-3-yne, 4-methyl-2,2-di-t-butylperoxypentane and combinations thereof. 
     Such peroxide compounds are typically employed in the present invention in the range of from about 0.1 to about 10 percent by weight, based on the total weight of the composition, with about 1 to about 5 percent by weight being desirable. 
     Conventional co-accelerators of free radical polymerization may also be used in conjunction with the inventive anaerobic cure accelerators. Such co-accelerators are typically of the hydrazine variety (e.g., APH), as disclosed in the &#39;330 and &#39;349 patents. 
     Stabilizers and inhibitors (such as phenols including hydroquinone and quinones) may also be employed to control and prevent premature peroxide decomposition and polymerization of the composition of the present invention, as well as Chelating agents [such as the tetrasodium salt of ethylenediamine tetraacetic acid (“EDTA”)] to trap trace amounts of metal contaminants therefrom. When used, chelators may ordinarily be present in the compositions in an amount from about 0.001 percent by weight to about 0.1 percent by weight, based on the total weight of the composition. 
     The inventive anaerobic cure accelerators may be used in amounts of about 0.1 to about 10 percent by weight, such as about 1 to about 5 percent by weight, based on the total weight of the composition. When used in combination with conventional accelerators (though at lower levels, for such conventional accelerators), the inventive accelerators should be used in amounts of about 0.01 to about 5 percent by weight, such as about 0.02 to about 3 percent by weight. 
     Metal catalyst solutions or pre-mixes thereof are used in amounts of about 0.03 to about 0.1 percent by weight. Other agents such as thickeners, non-reactive plasticizers, fillers, toughening components (such as elastomers and rubbers), and other well-known additives may be incorporated therein where the art-skilled believes it would be desirable to do so. 
     The present invention also provides methods of preparing and using the inventive anaerobic adhesive compositions, as well as reaction products of the compositions. 
     The compositions of the present invention may be prepared using conventional methods which are well known to those persons of skill in the art. For instance, the components of the inventive compositions may be mixed together in any convenient order consistent with the roles and functions the components are to perform in the compositions. Conventional mixing techniques using known apparatus may be employed. 
     The compositions of this invention may be applied to a variety of substrates to perform with the desired benefits and advantages described herein. For instance, appropriate substrates may be constructed from steel, brass, copper, aluminum, zinc, glass and other metals and alloys, ceramics and thermosets. The compositions of this invention demonstrate particularly good bond strength on steel, glass and aluminum. An appropriate primer may be applied to a surface of the chosen substrate to enhance cure rate. Or, the inventive anaerobic cure accelerator may be used as a primer itself. See e.g. U.S. Pat. No. 5,811,473 (Ramos). 
     In addition, this invention provides a method of preparing an anaerobic curable composition, a step of which includes mixing together a (meth)acrylate component and an anaerobic cure-inducing composition, desirably substantially free of saccharin, but including the inventive anaerobic cure accelerators within structure I. 
     The invention also provides a process for preparing reaction product from the anaerobic adhesive composition of the present invention, the steps of which include applying the composition to a desired substrate surface and exposing the composition to an anaerobic environment for a time sufficient to cure the composition. 
     This invention also provides a method of using as a cure accelerator for anaerobic curable compositions compounds within structure I. 
     And the present invention provides a method of using an anaerobic cure accelerator within structure I as a replacement for some or all of the saccharin as a cure accelerator for anaerobic curable compositions. Of course, the present invention also provides for a bond formed between two mated substrates with the inventive composition. 
     In view of the above description of the present invention, it is clear that a wide range of practical opportunities is provided. The following examples are provided for illustrative purposes only, and are not to be construed so as to limit in any way the teaching herein. 
     EXAMPLES 
     An investigation was performed to evaluate certain compounds within structure I as a replacement for some or all of the saccharin used in anaerobic curable compositions. 
     These new cure systems were compared with control formulations containing the conventional cure components, toluidines and saccharin, by 82° C. accelerated stability, fixture time, and one hour/24 hour adhesion tests on nut/bolt specimens. 
     Structures II and III were evaluated individually and in combination to determine their suitability as a cure accelerator in the anaerobic curable compositions. 
     The inventive anaerobic cure accelerators and PEGMA, MA, saccharin, DE-p-T, DM-o-T, CHP, and APH were obtained commercially from Fluka and Aldrich Chemical Co. 
     Proton. Nuclear Magnetic Resonance (“ 1 H NMR”) analyses were performed using a Varian 300 Hz Gemini Spectrophotometer. Infrared (“IR”) spectral analyses were performed on neat samples using a Perkin Elmer Instruments Spectrum One FT-IR Spectrophotometer with a Universal ATR Sampling Accessory. 
     A. Adhesive Formulations with Sulfonamide Derivatives 
     Samples A-H were prepared from the noted components in the listed amounts in Tables 1 and 2, by mixing with a mechanical stirrer in glass vials. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 COMPONENTS 
                   
                 Sample/(Amt./wt. %) 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Type 
                 Identity 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 (Meth)acrylate 
                 Base 
                 91.1  
                 91.1  
                 91.1  
                 91.1  
               
               
                   
                 Anaerobic 
               
               
                   
                 PEG 200 
                  2.52 
                  2.52 
                  2.52 
                  2.52 
               
               
                   
                 MO 
               
               
                 Conventional 
                 Saccharin 
                  3.78 
                 — 
                 — 
                 — 
               
               
                 Accelerator 
               
               
                 Toluidine 
                 DE-p-T 
                 0.8 
                 0.8 
                 0.8 
                 0.8 
               
               
                 Inventive 
                 NCS 
                 — 
                 — 
                  3.78 
                  1.89 
               
               
                 Accelerator 
                 SBS 
                 — 
                  3.78 
                 — 
                  1.89 
               
               
                 Peroxide 
                 CHP 
                 1.8 
                 1.8 
                 1.8 
                 1.8 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 COMPONENTS 
                   
                 Sample/(Amt./wt. %) 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Type 
                 Identity 
                 E 
                 F 
                 G 
                 H 
               
               
                   
               
               
                 (Meth)acrylate 
                 Base 
                 91.1  
                 91.1  
                 91.1  
                 91.1  
               
               
                   
                 Anaerobic 
               
               
                   
                 PEG 200 
                  2.52 
                  4.32 
                  4.32 
                  4.32 
               
               
                   
                 MO 
               
               
                 Conventional 
                 Saccharin 
                  1.89 
                  3.78 
                 — 
                  1.89 
               
               
                 Accelerator 
               
               
                 Toluidine 
                 DE-p-T 
                 0.8 
                 0.8 
                 0.8 
                 0.8 
               
               
                 Inventive 
                 NCS 
                  1.89 
                 — 
                  1.89 
                  1.89 
               
               
                 Accelerator 
                 SBS 
                 — 
                 — 
                  1.89 
                 — 
               
               
                 Peroxide 
                 CHP 
                 1.8 
                 — 
                 — 
                 — 
               
               
                   
               
            
           
         
       
     
     The Base Anaerobic was prepared from the following components in the noted parts by weight: 
                                             Component   Parts                                                    Polyethylene glycol (PEG) dimethacrylate   62.67           Polyethylene glycol (PEG) 200 mono oleate   26.13           Chelator   0.80           Stabilizer   1.50                        
B. Physical Properties
 
     Break and Prevail Strengths 
     For the break/prevail adhesion tests, the specimens were pre-torqued to 44 in lbf and maintained at ambient temperature for a number of time intervals, and evaluated for performance. The time intervals were: 0.5 hours, 1 hour, hours, 4 hours and 24 hours. The break and prevail torque strengths were observed and recorded for the specimens at ambient temperature for these time intervals. The torque strengths were measured on a calibrated automatic torque analyzer. 
     The data for these evaluations is provided herein in Table 3 and illustrated in  FIGS. 1A and 1B . Each sample was evaluated in triplicate at the five time intervals noted. 
     
       
         
           
               
               
             
               
                   
                 TABLE 3 
               
             
            
               
                   
                   
               
               
                   
                 Breakloose/180 Prevail (in lbs) 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 30 
                 60 
                 120 
                 240 
                 1440 
               
               
                   
                 ½ Hour 
                 1 Hour 
                 2 Hour 
                 4 Hour 
                 24 Hour 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                 180 
                   
                 180 
                   
                 180 
                   
                 180 
                   
                 180 
               
               
                 Sample 
                 Break 
                 Prevail 
                 Break 
                 Prevail 
                 Break 
                 Preval 
                 Break 
                 Prevail 
                 Break 
                 Prevail 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 A 
                 81 
                 9 
                 112 
                 17 
                 125 
                 22 
                 165 
                 27 
                 158 
                 43 
               
               
                   
                 90 
                 13 
                 130 
                 22 
                 163 
                 27 
                 165 
                 27 
                 160 
                 42 
               
               
                   
                 88 
                 13 
                 111 
                 13 
                 143 
                 30 
                 180 
                 38 
                 170 
                 31 
               
               
                 D 
                 92 
                 12 
                 128 
                 16 
                 167 
                 26 
                 130 
                 22 
                 198 
                 36 
               
               
                   
                 106 
                 14 
                 152 
                 28 
                 138 
                 19 
                 176 
                 22 
                 170 
                 29 
               
               
                   
                 97 
                 13 
                 116 
                 16 
                 131 
                 20 
                 155 
                 27 
                 185 
                 23 
               
               
                 E 
                 76 
                 9 
                 113 
                 15 
                 140 
                 22 
                 146 
                 31 
                 160 
                 33 
               
               
                   
                 85 
                 7 
                 116 
                 16 
                 152 
                 31 
                 177 
                 31 
                 170 
                 37 
               
               
                   
                 72 
                 9 
                 102 
                 16 
                 160 
                 25 
                 170 
                 33 
                 155 
                 38 
               
               
                 F 
                 85 
                 16 
                 111 
                 18 
                 113 
                 23 
                 126 
                 24 
                 94 
                 33 
               
               
                   
                 85 
                 14 
                 102 
                 20 
                 112 
                 22 
                 112 
                 22 
                 88 
                 21 
               
               
                   
                 78 
                 11 
                 113 
                 16 
                 127 
                 23 
                 133 
                 24 
                 92 
                 14 
               
               
                 G 
                 75 
                 13 
                 124 
                 14 
                 107 
                 18 
                 133 
                 19 
                 110 
                 28 
               
               
                   
                 77 
                 11 
                 97 
                 18 
                 97 
                 18 
                 141 
                 24 
                 116 
                 23 
               
               
                   
                 80 
                 15 
                 113 
                 18 
                 102 
                 19 
                 126 
                 18 
                 127 
                 27 
               
               
                 H 
                 52 
                 8 
                 88 
                 15 
                 87 
                 18 
                 119 
                 25 
                 86 
                 23 
               
               
                   
                 63 
                 8 
                 82 
                 13 
                 85 
                 15 
                 114 
                 18 
                 82 
                 17 
               
               
                   
                 58 
                 9 
                 75 
                 13 
                 73 
                 15 
                 135 
                 21 
                 104 
                 20 
               
               
                   
               
            
           
         
       
     
     Sample A (with saccharin and CHP) is shown as a comparison against Samples D and E (with two representative saccharin derivatives used individually and in combination). Sample F (with saccharin, but no CHP) is shown as a comparison against Samples B and B (with two representative saccharin derivatives used individually and in combination). 
     These derivatives are useful in anaerobic curable compositions as a replacement for some of or all of the saccharin and/or CHP typically used as accelerators. The inventive cure accelerators display good solubility, stability and anaerobic activity.