Open access peer-reviewed chapter

UV and Thermal Cure Epoxy Adhesives

Written By

Chunfu Chen, Bin Li, Chao Wang, Shuichi Iwasaki, Masao Kanari and Daoqiang Lu

Submitted: November 15th, 2017 Reviewed: October 22nd, 2018 Published: November 16th, 2018

DOI: 10.5772/intechopen.82168

Chapter metrics overview

1,578 Chapter Downloads

View Full Metrics

Abstract

Typical commercial UV and thermal cure epoxy adhesives have been reviewed and compared. UV cure cationic epoxy adhesives are primarily composed of cycloaliphatic epoxy resin and cationic photoinitiator. UV cationic epoxy adhesives have no surface cure issue and possess low cure shrinkage and good adhesion performance but need post-thermal cure to achieve full adhesion performance in use. Hybrid UV acrylate and thermal cure epoxy adhesives are primarily composed of acrylate monomer, free radical photoinitiator, epoxy resin and curing agent. The hybrid epoxy adhesives combine fast UV curability of acrylate composition and high adhesion performance of thermal cure epoxy composition. A new type initiator free hybrid one-component UV and thermal cure adhesive has been also introduced. It is mainly composed of maleimide compound, acrylic monomer, partially acrylated epoxy resin, epoxy resin and latent curing agent. Its UV cure and thermal cure behaviour have been studied by FT-IR spectroscopy measurement.

Keywords

  • UV cure
  • thermal cure
  • cationic
  • free radical
  • acrylate
  • epoxy adhesive

1. Introduction

Epoxy adhesives are widely used in structural bonding applications ranging from general industry, semiconductor packaging, electronics assembly and automobile production to aerospace market because of their strong chemical structure and good adhesion to various substrates [1, 2, 3, 4, 5, 6, 7, 8, 9]. Epoxy adhesives are primarily composed of epoxy resin and curing agent. Figure 1 illustrates chemical structure and key features of various functional groups for bisphenol A diglycidyl ether, the most standard epoxy resin used in epoxy adhesives. Epoxide possesses high reactivity. It can react with amines, thiols, anhydrates or phenols almost equivalently via polyaddition mechanism at suitable certain conditions to become strong cross-linked thermoset resins. As shown in Scheme 1 [10], epoxide reacts almost equivalently with active hydrogen in amine curing agent via polyaddition mechanism. Epoxide can also polymerize via either anionic or cationic polymerization mechanism. As shown in Scheme 2 [11], epoxide can polymerize via anionic polymerization mechanism initiated by anionic ion resulted from reaction of imidazole compound and epoxide. Epoxy adhesives can be cured at different temperature conditions based mainly on the curing agent type used but will normally need relatively long cure time ranging from half hour to a few days. Aliphatic amine-based epoxy adhesives, the most commonly used type, start to cure at room temperature. Thiol-based epoxy adhesives, the fastest cure type, start to cure even at low refrigerator temperature. Anhydrate-, phenol-, aromatic amine- or catalyst-based epoxy adhesives will normally need elevated temperature to achieve full cure. Generally speaking, epoxy adhesives designed to cure at elevated temperature which are commonly called as thermal cure epoxy adhesives have higher degree of cross-linking structure and glass transition temperature and thus show better performance than epoxy adhesives designed for cure at room temperature. Thermal cure epoxy adhesives can be also formulated as one-component type by the use of latent curing agents for easy handling. One-component thermal cure epoxy adhesives have been increasingly used in various applications such as semiconductor packaging, electronics assembly and automobile production where high production efficiency and high adhesion performance are required. Recently, UV and thermal cure epoxy adhesives have been developed and commercialized to meet further higher production efficiency of required applications such as precise optical sensor packaging and display assembly [12, 13, 14, 15].

Figure 1.

Structure and key features of bispheol A diglycidyl ether.

Scheme 1.

Polyaddition reaction of epoxy resin with amine curing agent.

Scheme 2.

Anionic polymerization of epoxy resin via imidazole catalyst.

There are mainly two types of commercial UV and thermal cure epoxy adhesives: UV cure cationic epoxy adhesives and hybrid UV acrylate and thermal cure epoxy adhesives. UV cationic cure epoxy adhesives are primarily composed of cycloaliphatic epoxy resin and cationic photoinitiator. UV cationic epoxy adhesives have no surface cure issue and possess low cure shrinkage and good adhesion performance but need post-thermal cure to achieve full cure. Hybrid UV acrylate and thermal cure epoxy adhesives are primarily composed of acrylate monomer, free radical photoinitiator, epoxy resin and curing agent. The hybrid epoxy adhesives combine fast UV curability of acrylate composition and high adhesion performance of thermal cure epoxy composition.

Advertisement

2. UV cationic epoxy adhesives

UV cationic epoxy adhesives are primarily composed of epoxy resin and cationic photoinitiator [16, 17, 18, 19, 20]. Cycloaliphatic-type epoxy resins are usually selected for UV cationic epoxy adhesives because of faster cationic polymerization rate than that of normal bisphenol A diglycidyl ether-type epoxy resin. Chemical structure of typical commercially available epoxy resins suitable for cationic epoxy adhesives is shown in Figure 2. Cationic photoinitiator is the key raw material to formulate UV cationic epoxy adhesives. There are mainly two types of cationic photoinitiators: Bronsted acid and Lewis acid generator. Sulfonium and iodonium salts that can generate Bronsted acid are most commonly used as cationic photoinitiator. Figure 3 shows chemical structure of typical commercially available cationic photoinitiators.

Figure 2.

Common commercially available epoxy resins for cationic epoxy adhesives.

Figure 3.

Chemical structure of common UV cationic photoinitiator.

As illustrated in Scheme 3 [21], photoinitiator in UV epoxy adhesives absorbs UV energy to generate strong acid that will react with epoxy to produce cationic which can initiate homo-polymerization of epoxy resin. UV cationic epoxy adhesives will need some longer cure time compared to UV cure acrylate-based adhesive. In actual use, a post-thermal cure of UV cationic epoxy adhesives after the UV radiation is commonly used for full cure to assure satisfactory adhesion performance. Compared to common acrylate-based UV adhesives, UV cationic epoxy adhesives have much lower cure shrinkage because of the epoxy structure and have no surface cure issue that is resulted from oxygen inhibition to free radical polymerization since they cure via cationic polymerization. By contrast, UV cationic epoxy adhesives are not suitable for alkali-type substrates which stop cationic polymerization.

Scheme 3.

UV cationic polymerization of epoxy adhesives.

UV cationic epoxy adhesives have been commercialized and used in optical parts bonding, sensor packaging and display panel assembly applications [22, 23, 24, 25, 26]. The authors have found that adhesion reliability performance of UV cationic epoxy adhesives can be much improved by the combination use of cationic photoinitiator with thermal cationic initiator [27].

Advertisement

3. Hybrid UV acrylate and thermal cure epoxy adhesives

Most widely used UV cure adhesives are acrylate-based compositions [28, 29, 30, 31, 32]. Acrylate-based UV cure adhesives are primarily composed of acrylate monomer, acrylate oligomer and photoinitiator. As shown in Scheme 4 [33], the photoinitiator formulated in an acrylate-based adhesive absorbs light energy via UV radiation to generate free radical which can rapidly initiate polymerization of acrylate compositions. Acrylate-based UV cure adhesives can be cured within seconds. Limitations of UV cure acrylate-based adhesives are the surface cure issue, shadow cure problem, high cure shrinkage and poor humidity reliability. Surface cure issue is resulted from oxygen inhibition to free radical polymerization of acrylate. Shadow cure problem always occurs at the area where light cannot approach. Relatively high cure shrinkage and poor humidity reliability are caused from acrylate chemical structure.

Scheme 4.

UV cure mechanism of free radical polymerization of acrylate adhesives.

By the combination of UV acrylate composition with thermal cure epoxy composition, UV and thermal cure hybrid epoxy adhesives have been developed and commercialized for over two decades [34, 35, 36, 37, 38]. Acrylate monomer, epoxy resin, photoinitiator and epoxy curing agent are at least contained in the UV and thermal cure hybrid adhesives. These hybrid adhesives combine advantages from both UV acrylate proportion and thermal cure epoxy part. Adhesion reliability performance could be much improved by the introduction of the epoxy composition compared to the normal acrylate composition. In the meantime, production efficiency could be much improved by shortening the fixture time to seconds via UV cure compared to at least dozens of minutes needed for thermal cure epoxy adhesives. Surface cure issue, shadow cure issue and high cure shrinkage of acrylate-based UV adhesives could also be improved to certain degree because of lower contents of free radical curable acrylate compositions. In some cases, a thermal initiator such as peroxide is also formulated in the hybrid adhesive to assure curing remained acrylate compositions after the UV radiation or those at shadow area. Advantages and limitations of UV cationic epoxy adhesives, hybrid UV acrylate and thermal cure epoxy adhesives are compared with those of UV acrylate adhesives in Table 1.

Adhesive typeUV acrylateUV cationic epoxyHybrid thermal cure epoxy
Key compositionsAcrylateEpoxy resinAcrylate
PhotoinitiatorCationic photoinitiatorPhotoinitiator
Epoxy resin
Curing agent
Polymerization
UV cureRadicalCationicRadical
Thermal cureNACationicPolyaddition, anionic
Oxygen inhibitionYesNoPartially
Alkali inhibitionNoYesNo
UV curabilityHighMediumHigh
Post-thermal cureNo needPreferredNeed
Shadow cureNoPartiallyYes
Cure shrinkageHighLowLow
AdhesionModerateGoodGood

Table 1.

Comparison of UV acrylate, cationic epoxy and hybrid thermal cure epoxy.

Advertisement

4. Initiator free hybrid epoxy adhesives

Photoinitiator is the key material to formulate UV cure compositions. In actual cure process, however, several small molecules are usually generated as byproducts. Additionally, photoinitiator itself will not be consumed completely in actual use at most cure conditions and will remain in the cured materials as just contaminants. As shown in Scheme 5, for the use of benzyl dimethyl ketal (BDMK) as photoinitiator, for example, Sitmann et al. [39] described that there are at least three small molecules generated during its UV light decomposition. These small molecular byproducts, together with the remained photoinitiator, cannot be chemically bonded to the cured adhesive. For sensitive high precise substrate bonding applications such as fine semiconductor packaging or display assembly, there are big concerns on contaminants from low molecule chemicals such as these byproducts, remained photoinitiator during UV curing process on sensitive semiconductor substrate or display materials. In addition, the remained photoinitiator may initiate or accelerate chemical reaction of cured adhesive materials during the actual use and potentially damage its adhesion reliability performance. Initiator free UV cure adhesive will not have these concerns.

Scheme 5.

Photo-reaction mechanism of BMDK.

Recently, the authors invented and reported a new type high-performance UV and thermal curable hybrid epoxy adhesive that is completely an initiator free composition but still possesses good UV curability and satisfactory thermal curability, suitable for use in high-end display assembly applications [40, 41, 42].

Maleimide compounds have been studied for years in photoinitiator-free UV curing systems [43, 44, 45, 46]. As illustrated in Scheme 6, maleimide compound can adsorb light energy and generate small amount of free radical. In the meantime, maleimide itself is a good monomer for free radical polymerization. Compared to normal photoinitiator acrylate cases, however, its UV cure efficiency is much lower.

Scheme 6.

Radical generation of maleimides via UV radiation.

The new type hybrid epoxy resin adhesive is mainly composed of a liquid bismaleimide compound, partially acrylated bisphenol A epoxy resin, acrylic monomer, epoxy resin and latent curing agent. Chemical structure of typical reactive materials used is shown in Figure 4. The new type adhesive does not contain any conventional initiator, either photoinitiator or thermal initiator such as peroxide compound. It is a complete initiator free hybrid epoxy adhesive. Its UV fixture time was 5 s at 100 mW/cm2 with high-pressure mercury lamp used. Good adhesion on glass substrate has been also confirmed.

Figure 4.

Chemical structure of reactive materials used.

FT-IR was performed to measure and analyze quantitatively cure behaviour of the adhesive sample [46, 47, 48]. The spectrum of adhesive samples cured at UV cure and UV + thermal cure conditions as well as non-cure samples was measured by the use of Varian 610-IR Fourier transform infrared (FT-IR) spectroscopy. Figure 5 IR spectrum of adhesive sample cured at UV only condition was shown compared to non-cure sample. IR spectrum of adhesive samples cured at UV + thermal cure condition was shown compared to non-cure sample in Figure 6. The conversion rate was further calculated from the decrease of the 1405 cm−1 absorption peak area attributed to acrylic double bond, the 690 cm−1 peak area attributed to maleimide double bond and the 915 cm−1 peak area attributed to epoxy group. As summarized in Table 2, a conversion rate of 62% of acrylic and 95% of maleimide double bonds had been achieved at this UV cure condition. This result confirmed that most part of acrylic and almost all maleimide double bonds had been cured during this UV cure condition. As expected, epoxy group cured only at thermal cure condition.

Figure 5.

FT-IR spectrum of adhesive cured at UV only condition, in blue, compared to non-cure sample.

Figure 6.

FT-IR spectrum of adhesive cured at UV + thermal cure condition, in blue, with compared to non-cure sample.

Cure conditionC=C conversion rate (%)Epoxy conversion rate (%)
AcrylateBismaleimide
UV cure only, 100 mW/cm2 × 30 s62950
UV + thermal cure, 100 mW/cm2 × 30 s + 120°C × 60 min1009685
Thermal cure only, 120°C × 60 min679569

Table 2.

Conversion rate of C=C group and epoxy group measured by FT-IR.

Very interestingly, it was found, as shown in Table 2, that remained uncured acrylic double bonds at UV cure process continued to react, and the conversion rate increased eventually to 100% at post-thermal cure condition. In the meantime, conversion rate of acrylic double achieved 67 and 95% at thermal cure only condition, respectively. As described previously, the adhesive sample does not contain any thermal initiator component such as peroxide. Nevertheless, UV cure components of the adhesive sample showed also very good thermal curability. From epoxy resin part, conversion rate of epoxy group of adhesive sample cured at thermal cure only condition was lower than that cured at UV + thermal cure condition.

Based on this result, acrylic and maleimide double bonds reacted most probably with the epoxy curing agent, dihydrazine.

Advertisement

5. Summary

UV and thermal cure epoxy adhesives have been successfully used in high-end applications such as optical component bonding, sensor packaging and display panel assembly where high production efficiency and high adhesion performance are required. There are mainly two types of commercialized UV and thermal cure epoxy adhesives: UV cure cationic epoxy adhesives and hybrid UV acrylate and thermal cure epoxy adhesives. UV cure cationic epoxy adhesives are primarily composed of cycloaliphatic epoxy resin and cationic photoinitiator. UV cationic epoxy adhesives have no surface cure issue and possess low cure shrinkage and good adhesion performance but need post-thermal cure to achieve full adhesion performance. Hybrid UV acrylate and thermal cure epoxy adhesives are primarily composed of acrylate monomer, free radical photoinitiator, epoxy resin and curing agent. The hybrid epoxy adhesives combine fast UV curability of acrylate composition and high adhesion performance of thermal cure epoxy composition. A new type initiator free hybrid one-component UV and thermal cure adhesive has been also introduced. It is mainly composed of maleimide compound, acrylic monomer, partially acrylated epoxy resin, epoxy resin and latent curing agent. The new hybrid epoxy adhesive possesses good UV curability and satisfactory thermal curability and is suitable for use as high performance required applications.

References

  1. 1. Petrie EM. Handbook of Adhesives and Sealants. MicGraw-Hill; 2006. 355p
  2. 2. Sancaktar E, Bai L. Electrically conductive epoxy adhesives. Polymer. 2011;3:427-466. DOI: 10.3990/polym3010427
  3. 3. Severijin C, Teixeira de Freitas S, Poulis JA. Susceptor-assisted induction curing behavior of a two component epoxy paste adhesive for aerospace applications. International Journal of Adhesion and Adhesives. 2017;75:155-164. DOI: 10.1016/j.ijadhadh.2017.03.005
  4. 4. Vidil T, Tournilhac F, Musso S, Robisson A, Leibler L. Control of reactions and network structures of epoxy thermosets. Progress in Polymer Science. 2016;62:126-179. DOI: 10.1016/j.progpolymsci.2016.06.03
  5. 5. Zotti A, Zuppolini S, Zarrelli M, Borriello A. Fracture toughening mechanisms in epoxy adhesives. In: Adhesives—Applications and Properties. London: InTech; 2016. pp. 237-269. DOI: 10.57772/65250
  6. 6. Lewis AF. Epoxy resin adhesives. In: May CA, editor. Epoxy Resins—Chemistry and Technology. 2nd ed. New York: Marcel Dekker; 1988. p. 653
  7. 7. Jin F-L, Li X, Park S-J. Synthesis and applications of epoxy resin: A review. Journal of Industry and Engineering Chemistry. 2015;29:1-11. DOI: 10.1016/j.jiec.2015.03.026
  8. 8. Groulding TM. Epoxy resin adhesives. In: Pizzi A, Mittal KL, editors. Handbook of Adhesive Technology. 2nd ed. New York: Marcel Dekker; 2003. pp. 809-824
  9. 9. Petrie EM. Epoxy Adhesive Formulations. New York: McGraw-Hill. p. 2006
  10. 10. Thomas R, Sinturel C, Thomas S, El Akiaby EMS. Introduction. In: Thomas S, Sinturel C, Thomas R, editors. Micro- and Nanostructured Epoxy/Rubber Blends. Berlin: Wiley-VCH Verlag; 2014. p. 3
  11. 11. Heise MS, Martin GC. Curing mechanism and thermal properties of epoxy-imidazole systems. Macromolecules. 1989;22:99-104
  12. 12. Chen C, Iida K. Adhesives for flat-panel display manufacture. In: Adhesives, 2. Applications in Ullmann’s Encyclopedia of Industry Chemistry. Berlin: Wiley-VCH Verlag; 2010. p. 519
  13. 13. Herold J, Kluke M. UV light-curing adhesives for increased productivity. Radtech Report. 2012;3:27-31
  14. 14. Sangermano M, Razza N, Crivello JV. Cationic UV-curing: Technology and applications. Macromolecular Materials and Engineering. 2014;299:775-793. DOI: 10.1002/mame.201300349
  15. 15. Javadi A, Shokouhi H, Sobani M, Soucek MD. Cure-on-command technology: A review of the current state of the art. Progress in Organic Coatings. 2016;100:2-31. DOI: 10.1016/j.porgcoat.2016.02.014
  16. 16. Lee C-S, Fan S, Seghier Z, Boey FYC, Abadie MJM. Photoreactivity of epoxy resins. Macromolecules. 2007;3:84-90
  17. 17. Voytekunas VY, Ng FL, Abadie MJM. Kinetics study of the UV-initiated cationic polymerization of cycloaliphatic diepoxide resins. European Polymer Journal. 2008;44:3640-3649. DOI: 10.106/j.eurpolymj.2008.08.043
  18. 18. Golaz B, Michaud V, Leterrie Y, Manson J-AE. UV intensity, temperature and dark-curing effects in cationic photo-polymerization of a cycloaliphatic epoxy resin. Polymer. 2012;53:2038-2048. DOI: 10.1016/j.polymer.2012.03.025
  19. 19. Jui-Hsun L, Youngblood JP. Adhesive bonding of carbon fiber reinforced composite using UV-curing epoxy resin. Composites Part B Engineering. 2015;82:221-225. DOI: 10.1016/j.compositesb.2015.08.022
  20. 20. Atif M, Bongiovanni R, Yang J. Cationically UV-cured epoxy composites. Polymer Reviews. 2015;55:90-106. DOI: 10.1080/15583724.2014.963236
  21. 21. Corcione C, Malucelli G, Frigione M, Maffezzoli A. UV-curable epoxy systems containing hyperbranched polymers: Kinetics investigation by photo-DSC and real-time FT-IR experiments. Polymer Testing. 2009;28:157-164. DOI: 10.1016/j.polymertesting.2008.11.002
  22. 22. Kong S. Composition of cationic initiator and oxetane compound. US Patent 7902305
  23. 23. Kong S, Grieshaber SE. Radiation or thermally curable barrier sealants. US Patent 8278401
  24. 24. Hoshino T, Goto Y, Yada K. Resin composition. US Patent application 20150210905
  25. 25. Gan Y, Chen C, Terada K. Cationically photocurable epoxy composition. US Patent 7456230
  26. 26. Chiang TH, Hsieh T-E. A study of monomer’s effect on adhesion strength of UV-curable resins. International Journal of Adhesion and Adhesives. 2006;26:520-531. DOI: 10.1016/j.ijadhadh.2005.07.004
  27. 27. Chen C, Gan Y. Cationically curable epoxy composition. US Patent 7795744
  28. 28. Velankar S, Pazos J, Cooper SL. High-performance UV-curable urethane acrylates via deblocking chemistry. Journal of Applied Polymer Science. 1996;62:1361-1376
  29. 29. Fourassier J-P, Lalevee J. Photoinitiator for Polymer Synthesis. Berlin: Wiley-VCH Verlag; 2012. p. 41
  30. 30. Ebnesajjad S. Adhesive Technology Handbook. 2nd ed. New York: William Andew; 2008. p. 124
  31. 31. Fakley ME. Radiation-cured adhesives. In: Packham DE, editor. Handbook of Adhesion. John Wiley & Sons; 2005. p. 395
  32. 32. Dekker C. UV-radiation curing of adhesives. In: Cognard P, editor. Adhesives and Sealants. Elsevier; 2002. p. 303
  33. 33. Allen NS. Photoinitiators for UV and visible curing of coating: Mechanisms and properties. Journal of Photochemistry and Photobiology A. 1996;100:101-107
  34. 34. Matsuda M. Sealants for one drop fill (ODF) process. In: Koide N, editor. The Liquid Crystal Display Story. New York: Springer; 2014. p. 199
  35. 35. Park C, Lee S, Park J, Kim H. Preparation and characterization of dual curable adhesives containing epoxy and acrylate functionalities. Reactive & Functional Polymers. 2013;73:641-646. DOI: 10.1016/j.reatfunctpolym.2013.01.012
  36. 36. Xiao M, He Y, Nie J. Novel bisphenol A epoxide-acrylate hybrid oligomer and its photopolymerization. Designed Monomers and Polymers. 2008;11:383-394. DOI: 10.1163/156855508X332522
  37. 37. Park Y, Lim D, Kim H, Park D, Sung I. UV- and thermal-curing behavior of dual-curable adhesives based on epoxy acrylate oligomers. International Journal of Adhesion and Adhesives. 2009;29:710-717. DOI: 10.1016/j.ijadhadh.2009.02.001
  38. 38. Su Y, Cheng L, Cheng K, Don T. Synthesis and characterization of UV- and thermos-curable difunctional epoxy acrylates. Materials Chemistry and Physics. 2012;132:540, 100-549
  39. 39. Sitmann E, Fuchs A, Worstatzky D. Photoinitiator: Their mechanism, use and applications. In: Florio JJ, Miller DJ, editors. Handbook of Coating Additives. Oxford: Taylor & Francis; 2004. pp. 61-126
  40. 40. Chen CF, Iwasaki S, Kanari M, Li B, Wang C, Lu D. High performance UV and thermal cure hybrid epoxy adhesive. IOP Conference Series: Materials Science and Engineering. 2017;213:012032. DOI: 10.1088/1757-899X/213/1/012032
  41. 41. Chen C. Sealing agent for liquid crystal dropping technology and method of manufacturing liquid crystal display. Japan Patent 5592081
  42. 42. Chen C. Sealant composition. Japan Patent 5845341
  43. 43. Bongiovanni R, Sangermano M, Malucelli G, Priola A. UV curing of photoinitiator-free systems containing bismaleimides and diacrylate resins. Progress in Organic Coatings. 2005;53:46-49. DOI: 10.1016/j.porgcoat.2004.11.009
  44. 44. Vazquez GP, Joly-Duhamel C, Boutevin B. Photopolymerization without photoinitiator of bismaleimide-containing oligo(oxypropylene)s. Macromolecular Chemistry and Physics. 2009;210:269-278. DOI: 10.1002/macp.200800510
  45. 45. Kuang W, Sabahi M, Nguyen C. Maleimide Reactive Oligomer for Wood Coating. RadTech Technical Proceeding. 2004. e/5
  46. 46. Gonzalez MG, Cabanelas JC, Baselga J. Applications of FTIR on epoxy resins—Identification, monitoring the curing process, phase separation and water uptake. In: Theophile T, editor. Infrared Spectroscopy—Materials Science, Engineering and Technology. London: InTech; 2012. pp. 261-284
  47. 47. Cholake ST, Mada MR, Raman RKS, Bai Y, Zhao X, Rizkalla S, et al. Quantitative analysis of curing mechanism of epoxy resin by mid- and near- FT-IR spectroscopy. Defence Science Journal. 2014;64(3):314-321. DOI: 10.14429/dsj.64.7326
  48. 48. Ohtsuka K, Kimura H, Ikeshita S, Nakao H, Tsubota S. Novel bismaleimide/diallylbisphenol A resin modified with multifunctional thiol containing isocyanuric ring and long-chain aliphatic unit. High Performance Polymers. 2015;28(5):591. DOI: 10.1177/0954008315591191

Written By

Chunfu Chen, Bin Li, Chao Wang, Shuichi Iwasaki, Masao Kanari and Daoqiang Lu

Submitted: November 15th, 2017 Reviewed: October 22nd, 2018 Published: November 16th, 2018