A Novel Thermal Curing Reaction of Oxetane Resin with Active Diester

Abstract

Thermal curing reactions of oxetane resins {mixtures of novolac type oxetane (PNOX) with 2,2 0 -bis{(3-ethyl-3-oxetanyl)methoxy}biphenyl (2,2 0 -BPOX) and mixtures of tris{4- [(3-ethyl-3-oxetanyl)methoxy]phenyl}methane (THPMOX) with 2,2 0 -BPOX with active diester, 4,4 0 -isopropylidenebis(2,6-dichlorophenyl diacetate) (IBDCPA) were examined using certain quaternary phosphonium salts as catalysts. The thermal curing reaction of oxetane resins with IBDCPA proceeded smoothly at C to produce insoluble gel products. However, the rate of gel production was strongly affected by catalyst concentration and reaction temperature, and gel products were obtained in the highest yield when the reaction was carried out at 190 C in bulk using 7 mol % of tetraphenylphosphonium chloride (TPPC) as a catalyst. The glass transition temperatures (T g )s and 5 weight-% of loss temperatures (T d 5% )s of the resulting gel products were determined by DSC and TGA analysis, and it was found that their T g s and T d 5% s were 97-118 C and 374-380 C, respectively, when the thermal curing reaction of oxetane resins PNOX/2,2 0 -BPOX with equivalent amount of cross-linker IBDCPA was performed using TPPC as a catalyst in bulk. On the other hand, the T g s and T d 5% s of gel products obtained from the reaction of oxetane resins THPMOX/2,2 0 -BPOX with IBDCPA using the same catalyst were 96-128 C and 381-386 C, respectively.KEY WORDS: Oxetane Resin / Polyfunctional Oxetane / Bis(oxetane) / Cross-linking Reagent / Active Bis(ester) / Gel Product / It is well known 1 that thermal curing reactions of epoxy resins with certain cross-linkers such as polyfunctional-amines, -phenols, -thiols, and -carboxylic acids proceed smoothly using appropriate catalysts. In these reaction systems, the cured epoxy resins produced pendant hydroxyl groups. It is thought that the produced pendant hydroxyl groups in the cured resins increased its glass transition temperature (T g ) and bondstrength between the resin and the surface of the substrate. Therefore, the thermal curing reactions of epoxy resins with the above cross-linkers have been widely used in many industries as coatings, paintings, elastomers, adhesions, and electronics. However, it has been pointed out recently that the generation of the hydroxyl groups in the cured resins strongly decreased electric insulation property of the epoxy resins after moisture exposure.About 15 years ago, we have successfully found 2 new addition reactions of oxiranes with active ester, active aryl ether, silyl ether, and phosphonyl ester. We also examined 3 their application to develop new epoxy resins with high performance and excellent functionality based on new organic reactions of the oxiranes. Then, we found that the cured epoxy resins using polyfunctional active esters can be achieved excellent electric insulating property. Therefore, these thermal curing systems have great possibilities to be used in industry, especially in electronic industry.On the other hand, 4-membered cyclic ethers, oxetanes have mostly same str...

“Kick-Starting” oxetane photopolymerizations

“…In addition to the oxetane monomers prepared using the three synthetic methods described above, a number of other novel oxetanes have been synthesized such as; silicon‐containing oxetanes, oxetane‐functionallized novolac resins, oxetane‐functional polymers for use in organic light emitting diodes (OLEDs) and oxetane esters . These efforts exemplify the great versatility of oxetane chemistry and illustrate the ease with which the oxetane group can be introduced into different substrates to produce polymerizable monomers, polymers and functional oligomers …”

Vinyl epoxide accelerators for the photoinitiated cationic polymerization of oxetane monomers

“…Several other groups have also been active in this field. [11,12,13] Several of these oxetane monomers are now being offered commercially. While the synthesis and mechanical properties of the UV-cured oxetanes were interesting, their photopolymerization rates were much too slow to be of interest for most of the major uses that were described in the introduction portion of this communication.…”

Instrumental Physical Analysis of Microwaved Glycerol Citrate Foams

“…Curing continues the polymerization/crosslinking reactions and is often peripheral to the actual manufacturing process, normally additives or thermal cooking is employed to control the rate of plastic curing in order to obtain a more satisfactory thermoset plastic [27]. Thermal curing is often conducted to complete the polymerization process and stabilize the polymers physical characteristics [28][29][30]. Heat curing of plastic polymers by thermal or microwave treatments often results in polymers with distinctly different physical characteristics [27,30].…”