FACILE SYNTHESIS OF BISPHENOL CP AND ITS DERIVATIVES:THERMAL AND CURING CHARACTERISTICS OF EPOXY RES

Abstract

6. Abstract of the invention: Title: Facile synthesis of bisphenol CP and its derivatives: Thermal and curing characteristics of epoxy resins and benzoxazines The present invention involves the development of facile production route for bisphenol CP (BCP) on reacting phenol with cyclopentanone in the presence of mixture of hydrochloric acid and sulphuric acid as catalysts over the temperature of about 80°C to 110°C for about 12 to 48 hour. The structural characterization of BCPwas carried out using NMR and mass spectra. The BCP synthesized was converted into epoxy resin (BCP-Ep) by reacting with epichlorohydrin in the presence of alkali at appropriate experimental conditions. Similarly, benzoxazines (BCP-ffa and BCP- ty) were prepared by reacting with paraformaldehyde and corresponding amines (furfurylamine and tyramine) under suitable experimental conditions and their curing behavior and thermal stability were studied. The values of molecular mass of BCP and BCP-epoxy resin obtained are 249.07 g/mol and 366.45 g/mol respectively. The polymerization temperature (Tp) and thermal stability of epoxy resin and 20 benzoxazines was studied using DSC and TGA respectively. Among the different catalysts studied BCP-Ep + ad, BCP-Ep + ad + dicy and BCP-Ep + ad + urea resulted lowest Tp values of 173°C and 240°C, I74°C and 232°C, 175°C and 234°C respectively. The Tp of BCP-ffa and BCP-ty were found to be 241°C and 231°C respectively. Similarly, the Tpbased benzoxazines in the presence of catalysts studied, the most suitable systems for fabrication of advanced composite components and their working range are BCP-ffa + odh (216°C) and BCP-ty + odh (155, 192°C). The highest value of decomposition temperature (Td) was found to be 430°C for cured BCP-Ep + gu. Similarly the highest value of Td was found to be 469°C for poly(BCPffa + ad + urea). The highest char yield was found to be 40% for cured BCP-Ep + atu. Similarly the char yield was found to be 46% for poly(BCP-ffa), 58% for poly(BCPffa + ad + urea), 37% for poly(BCP-ty), 47% for poly(BCP-ty + odh + urea). The present invention is considered as cutting-edge concept in the field of conversion of mono-basic sustainable bio-phenols into bio-polyphenols to substitute conventional polyphenols for the production of industrially valuable resins like epoxieo, benzoxazines, cyanate esters, polyesters and urethanes. Dated this 19th Day of October 2024 Signature of the applicant Dr. N. Saravanakumar Dr N Saravanakumar Principal PSG Institute of Technology and Applied Research , _ _ Coimbatore - 641062

Specification

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. Title of the Invention:
"Facile synthesis of bisphenol CP and its derivatives: Thermal and curing
characteristics of epoxy resins and benzoxazines"
2. Name of the Applicant:
PSG Institute of Technology and Applied Research
Address for communication:
The Principal
PSG Institute of Technology and Applied Research
Avinashi Road, Neelambur,
Coimbatore - 641 062, Tamilnadu.
Phone No: 0422 3933400
710083639
&
Nationality:
INDIAN
3. Preamble of the Description:
The following specification particularly describes the invention and the manner in
which it is to be performed.

4.
Description:
Title: Facile synthesis of bisphenol CP and its derivatives: Thermal and curing characteristics of epoxy resins and benzoxazines
Field of the invention
The present invention relates to the synthesis of bisphenol (BCP) from phenol and cyclopentanone (CP) to prepare BCP based benzoxazines and epoxy resin. BCP based benzoxazine resins were developed through Mannich condensation using specific amino-derivatives, paraformaldehyde and BCP based epoxy resin was also synthesized followed by epoxidation using epichlorohydrin under appropriate experimental conditions. The polymerization behavior of BCP based benzoxazines and epoxy with varied nature of molecular structures have been studied in the absence and in the presence of different types of curatives over the varied range of temperature and time. The BCP based benzoxazine and epoxy resins developed in the present invention can be used for the formulation of wide variety of industrial products namely coatings, adhesives, sealants, matrices and composites suitable for different industrial and engineering applications.

Background of the invention
The growing demands of modern industries, particularly in high-tech sectors, compel scientists to innovate and develop cutting-edge materials to meet evolving needs. In aerospace, reducing weight to increase pay load capacity and minimizing production costs and time are critical objectives. Traditionally, aerospace industries have relied on metal alloys, but recent years have seen a significant shift toward composite materials due to their superior performance. As a result, the development of cost-effective, high- performance technologies are essential. Advanced polymer composites offer numerous advantages, such as an exceptional strength-to-weight ratio, high stiffness, durability and resistance to fatigue, corrosion, chemicals and environmental conditions. These characteristics make them ideal for aerospace applications. Various resins, including phenolics, epoxies, benzoxazines,

cyanate esters and bismaleimides, were commonly used to produce composite components for aerospace structures.

Epoxy resins in particular, have found extensive applications due to their inherent properties, including excellent adhesion, low shrinkage, a low dielectric constant and outstanding mechanical and thermal properties. They 10 are widely utilized in adhesives for electronics, coatings and aerospace composites, etc.

Polybenzoxazines, a newer class of phenolic resins, were developed to overcome the limitations of traditional resole and novolac phenolics and are increasingly being used as alternatives. These materials exhibit superior 15 moisture resistance, low water absorption, fire resistance, low dielectric properties, high glass transition temperatures, and low volumetric shrinkage. Furthermore, they polymerize without releasing by-products and offer high stiffness, excellent char yield, and robust performance in high-temperature environments. Their resistance to moisture, chemicals and corrosive agents 20 makes polybenzoxazines particularly well-suited for extreme conditions.
Comparable to bismaleimide resins in mechanical performance, polybenzoxazines are widely applied in aerospace, transportation, oil and gas, and electronics industries, such as in printed circuit boards.

Thus, the shift toward advanced ' composite materials, especially 25 polybenzoxazines, represents a significant step forward in meeting the performance and economic challenges of modern aerospace applications. This necessitates the development of economically competitive technologies.

Objectives of the invention
The prime objective of the present invention is to develop low temperature curable BCP based benzoxazine through Mannich condensation and BCP epoxy by epoxidation using suitable precursors under appropriate experimental conditions. The benzoxazines and epoxy resin can be used for the formulation of a wide range of polymeric products in the form of coatings, adhesives, sealants, encapsulants, matrices and prepregs for advanced composites. The developed benzoxazine and epoxy resins are expected to replace existing epoxy resins / benzoxazines and suitable for fabrication of advanced composite products for different industrial and engineering applications.

Brief description of prior art W02020108989A1 (2019) The present inventions relates to the preparation of 3.3,5-trimethylcyclohexylidene bisphenol. Especially, the present invention
relates to the preparation of 3,3,5-trimethylcyclohexylidene bisphenol from
3,3,5-trimethylcyclohexanone and phenol in the presence of a gaseous acidic catalyst. The preparation comprises a first drying step and a second drying step wherein in the second drying step the temperature is increased in comparison
15 to first drying step or in the second drying step the pressure is lowered in comparison to first drying step, or in second drying step both the temperature is increased and the pressure is lowered in comparison to the first drying step
(dl).

US10669370B2 (2017) Compositions and curing agents comprising a benzylated Mannich base composition. The benzylated Mannich base composition includes a reaction product of (a) a substituted phenolic
compound having at least one substituent of formula (1):

wherein Ri is each independently a linear or branched alkyl group having 1 to 4 carbon atoms, and R2 is hydrogen, methyl, ethyl or phenyl, with (b) a benzylated polyalkylene polyamine (II):
(2)

30 wherein Ra is substituted or unsubstituted benzyl; Rois each independently Ra, or a hydrogen atom, or a group selected from Ci-Cie linear, cyclic, and branched alkyl, alkenyl, and alkaryl groups; X, Y, and Z are independently
selected from C2-C10 alkylene, and cycloalkylene groups; y is an integer from 0 to 7, and z is an integer from 0 to 4; and, optionally, (c) a multifunctional amine. Amine-epoxy compositions and articles produced from these compositions are also disclosed.

CN106414542B (2015) The invention provides a polyurethane modified epoxy resin with good processing operability such as casting or
impregnation in a composition state, a preparation method thereof and a composition thereof. The present invention is a polyurethanemodified
epoxy resin comprising a polyurethane obtained by modifying a secondary hydroxyl group-containing bisphenol epoxy resin (a) having an epoxy equivalent of 150 to 200g/eq and a hydroxyl equivalent of 2000 to 2600g/eq with a medium-high molecular weight polyol compound (b) having
a Mn of 200 or more, a poly isocyanate compound (c) and a low molecular weight polyol compound (d) having a Mn of less than 200 as a chain extender,
wherein the epoxy resin (a) is added to both terminals and/or one terminal by using 20 to 60% by weight of the epoxy resin (a) based on the total amount of the components (a), (b), (c) and (d).

US10370531B2 (2014) The present invention relates to a core-shell polymercontaining
epoxy resin composition, wherein, the composition contains 100 parts by weight of the epoxy resin (A) and 1 to 100 parts by weight of the coreshell
polymer (B), the core-shell polymer has the volume average particle diameter of 0.01 to 1 pm, the core part of the core-shell polymer (B) has the
glass transition temperature of less than 0° C., the shell part of the core-shell polymer (B) has the glass transition temperature of less than 25° C., and the shell part of the core-shell polymer (B) is polymerized with at least a monomer having an epoxy group CN104292078B (2014) The present invention relates to a kind of preparation method of bisphenol B, comprise the following steps successively: (a) drops into phenol, butanone, composite catalyst successively in reaction vessel, react 8 -15 hours at 30 - 40 DEG C after mixing, be then warming up to 55 - 65

DEG C of filtered while hot. obtain filtrate and filter residue; B described filtrate is placed in 200 ~ 700Pa. 75 ~ 90 DEG C of conditions under,
evaporation removing phenol obtains thick product; C described thick product is dissolved in alcoholic solvent and carries out crystallization. The preparation method of bisphenol B of the present invention, uses on- the one hand composite catalyst Pyrogentisinic acid and butanone to carry out catalysis, does not need after the reaction to use alkali lye neutralization and catalyzer can reuse, and has saved cost; Directly carry out refining again by evaporation removing phenol on the other hand, do not need to use water to
rinse product, be conducive to reducing the pollution to environment.

CN103965423A (2014) The invention discloses a preparation method of a
4,4'-(hexafluoroisopropylidene) diphenol (Bisphenol AF) phenolic resin. The preparation method is implemented by taking 4,4'-(hexafluoroisopropylidene) diphenol and formaldehyde as raw materials and taking an oxalic acid as a catalyst through carrying out condensation polymerization, so that the 4,4'-
20 (hexafluoroisopropylidene) diphenol phenolic resin is prepared. The preparation method is simple, excellent in performance and high in production rate, therefore, the preparation method has a great market potential.
CN103113573A (2012), The invention relates to a bisphenol Z containing polyaryletherketone random segmented copolymer and a preparation method
25 thereof. The method comprises the following step of performing nucleophilic substitution polycondensation-in a reaction medium to prepare the bisphenol containing polyaryletherketone random segmented copolymer based on
bisphenol Z, hydroquinone and 4,4-difluorobenzophenone as reaction monomers and an alkali metal salt as a salt-forming agent and catalyst. The bisphenol Z containing polyaryletherketone random segmented copolymer prepared by the invention is good in solubility, thermal stability and mechanical property, the raw materials are easy to obtain, and the preparation
method is simple and suitable for industrialized production, so that the copolymer has good application prospect in the fields of functional structural materials, high-temperature-resisting coatings, high-temperature-resisting separation films, solvent coatings, micro-electronics and the like.

CN102516035B (2011) The invention relates to a preparation method of bisphenol F, which is characterized in that under the condition of existence of an acid catalyst, phenol and formaldehyde are reacted to obtain the product. The acid catalyst is a mixture of inorganic acid and organic acid, and the mole ratio of the inorganic acid to organic acid is 10-2:1; the inorganic acid is oxygen-containing acid of phosphor, the organic acid is C1-C4 straight chain or branched chain monoacid or diacid. The invention has the advantages that under the condition that P/F is less than or equal to 10, the bisphenol F with high ortho-isomer (especially 2,4'-isomer) content can be obtained, the
production capability of the device can be increased, and the operation cost and the energy consumption are reduced.

JP2009263543A (2008) To provide: an epoxy-resin in which the total amount of chlorine content is reduced, and which is useful fora semiconductor sealing material, a packaging material for semiconductors and MEMS and the like, and a photosensitive material for semiconductors and MEMS; and its composition. The epoxy resin is prepared by reacting a bifunctional epoxy resin represented by formula (1) with a polyvalent phenol compound having at least three phenolic hydroxide groups in a molecule. The epoxy resin composition contains the epoxy resin. The cured product of the composition is also provided.

EP0495097A4 (1991) discloses a process of preparing 4,4'-Bisphenol S wherein sulfuric acid is reacted with an excess of phenol while removing water; the product purity is improved with respect to the 2,4'-BPS isomer by 30 adding toluene to the initial product mixture to crystallize and remove the desired 4,4'-BPS. The remaining material is recycled to isomerize the 2,4'-BPS to 4,4-BPS.

Summary of the invention
The present invention relates to the development of synthetic process route for production of industrially valuable and commercially potential BCP, BCP

epoxy and BCP benzoxazines. The BCP was synthesized using phenol with cyclopentanone in an acidic condition. The process route developed in the present invention is simple and innovative in many respects in terms of combination of cost competitive catalysts, moderate reaction time, temperature and percentage yield. In the present invention, BCP was prepared by reacting phenol and cyclopentanone using the stoichiometric quantities in the presence of mixture of hydrochloric acid and sulphuric acid catalysts under appropriate experimental conditions. The resultant BCP was converted into benzoxazines and epoxy resin.

Detailed description of the invention
The present invention relates to the development of facile process route for production of BCP was synthesized using phenol with cyclopentanone in the presence of combination of hydrochloric acid and sulphuric acid catalysts at the temperature of 80°C for a period of about 8 h. The present invention also relates to the synthesis of BCP based benzoxazines and epoxy resins through Mannich condensation using specific amino-derivatives and paraformaldehyde in the absence of any solvents. Similarly, BCP epoxy resins was synthesized followed by epoxidation using epichlorohydrin under appropriate experimental conditions. The cure behavior of the developed benzoxazines and epoxy resin with varied nature of molecular structures have been cured in the absence and in the presence of different types of curatives over the varied range of temperature and time. Hence, the benzoxazine and epoxy resin developed in the present invention can be considered as better alternative material and can be used for the formulation of wide variety of industrial products namely coatings, adhesives, sealants and matrices for fabrication of advanced composites suitable for different industrial and engineering applications.

Experimental Methods
Synthesis of BCP
Exactly weighed 2 mol of phenol was stirred vigorously with the mixture of cone. HC1 and sulfuric acid (1:1 v/v). Subsequently, 1 mol of cyclopentanone

(CP) was separately added slowly to the reaction mixture in an ice-cold condition and the reaction was conducted over the temperature range between 80°C and !20°C for about 24 hour. The progress of the reaction was monitored through thin layer chromatography (TLC). After the completion of the reaction, the product obtained was washed with water and then extracted with ethyl acetate, dried to obtain the desired product of bisphenol-CP (BCP), The chemical approach of BCP synthesis is shown in Figure 1.

Synthesis of BCP based benzoxazines
The BCP benzoxazines were synthesized by reacting 1 mol of BCP separately with 2 mol of furfurylamine (ffa), tyramine (ty) and 4 mol of paraformaldehyde in a 250 ml double-necked round bottomed flask equipped with a magnetic stirrer. The reactants were allowed to stir continuously for about 30 min in the absence of any solvents. After this initial phase, the temperature was gradually raised to 110°C and allowed the reaction mixture to stir for an additional 8 h until the reaction has been completed. Throughout the process, the progress of the reaction was closely monitored using thin layer chromatography (TLC). After the completion of the reaction, the crude product obtained was extracted using ethyl acetate. Subsequently, it was subjected to washing with 2M NaOH solution to remove any impurities or residual components, dried in a hot air oven and labeled as BCP-ffa and BCP- ty(Figurel).

Synthesis of BCP-epoxy (BCP-Ep)
BCP (1 mol) and epichlorohydrin (10 mol) and 20 ml of THF were charged into the round bottomed flask. The resulting reaction mixture was agitated for 1 h at room temperature. After that sodium hydroxide (20 mol) is slowly added and maintained at 5 h at 80°C. After cooling down to ambient temperature, a two phased mixture of ethyl acetate/distilled water was added to the above mixture. The extraction was carried out two times in an aqueous phase with ethyl acetate. Organic phase containing BCP based epoxy resin was washed again with an aqueous solution of sodium chloride and dried over anhydrous manganese sulphate. Excess of ethyl acetate and epichlorohydrin was

eliminated using rotary evaporator. The chemical approach of BCP-Ep resin synthesis is shown in Figure 2.
Curing studies in the absence and in the presence of catalysts
By differential scanning calorimetry (DSC) the synthesized BCP based benzoxazine and BCP-Ep resins curing behavior was studied in the absence
and in the presence of 5 wt% catalyst and the results obtained are presented in Tables 1 and 2 and illustrated in Figures 7 and 8. The catalysts utilized were adenine (ad), guanine (gu), oxalyldihydrazide (odh), 1 -allyl-2-thiourea (atu), dicyandiamide (dicy) and urea, cis-l,2,3,6-tetrahydrophthalic anhydride (tha).

Figure 1. Syntheses of BCP and BCP benzoxazines.

Figure 2. Synthesis of BCP-epoxy resin.
Mass analysis
The HRMS spectra of synthesized BCP and BCP-Ep are given in Figure 3.
The values of theoretical molecular weight calculated for BCP and BCP-Ep obtained are 254.13 g/mol and 366.45 g/mol respectively. The experimentally obtained highest molecular mass peak of BCP and BCP-Ep are 249.07 g/mol and 367.23 g/mol respectively, which are almost coincides with theoretical values calculated from the respective molecular structure.

'H-NMRand ,3C-NMR
Figures 4-6 shows the 'H and ,3C-NMR spectra of the synthesized BCP. BCPffa, BCP-ty and BCP-Ep respectively. The presence of respective proton and carbon peaks as described in the figures confirms the successful formation of BCP, BCP-ffa, BCP-ty and BCP-Ep.

Figure 3. High resolution mass spectra of BCP and BCP-Ep.
Figure 4. *H-NMR and ,3C-NMR spectra of BCP.
Figure 5. 'H-NMR and 13C-NMR spectra of BCP-ffa
Figure 6. 'H-NMR. and l3C-NMR spectra of BCP-ty
Curing Studies
Figure 7. DSC traces of (a) BCP-ffa and (b) BCP-ty in the absence and in the presence of catalysts.
Figure 8. DSC curves of BCP-Ep in the presence of catalysts.

Table 1. Curing parameters of BCP benzoxazines in the absence and in the presence of catalysts.

Table 2. Curing parameters of BCP-Ep resins in the presence of catalysts.
Thermal stability

Figure 9. TGA thermograms of (a) poly(BCP-ffa) and (b) poly(BCP-ty) in the
absence and in the presence of catalysts.
Figure 10. TGA thermograms of cured BCP-Ep in the presence of catalysts.

Table 3. Thermogravimetric data of poly(BCP-ffa) and poly(BCP-ty) in the absence and in the presence of catalysts.

Figure 10. TGA thermograms of cured BCP-Ep in the presence of catalysts.

Table 3. Thermogravimetric data of poly(BCP-ffa) and poly(BCP-ty) in the absence and in the presence of catalysts.
Table 4. Thermogravimetric data of cured BCP-Ep in the presence of
catalysts.

5.
Claims:
l/We claim
1. The present invention involves the development of facile production route for synthesizing bisphenol (BCP) using hydrochloric acid and sulphuric acid as catalysts over the temperature of about 80°C to 110°C for about 12 to 48 hour. The molecular structure of BCP was confirmed using NMR and Mass spectra. The BCP synthesized was converted into corresponding epoxy (BCP- Ep) and benzoxazines (BCP-ffa and BCP-ty) using appropriate chemical precursors under suitable experimental conditions.
+
2. The process of claim 1, wherein the BCP synthesized over the temperature range between 80°C and 110°C. The optimum temperature required for the reaction was found to be IOO°C.

3. The process of claim 1, wherein the BCP was synthesized over a period of reaction in the range between 12 and 48 hour. The optimum time required for the completion of reaction was found to be 24 hours.

4. The process of claim 1, wherein the values of experimental molecular mass of BCP and BCP-Ep obtained are 249.07 g/mol and 366.45 g/mol respectively.

5. The process of claim 1, wherein the percentage yield of BCP obtained from the optimized experimental conditions was found to be 85%.

6. The process of claim I, wherein the BCP synthesized was converted into epoxy resin (BCP-Ep) by reacting with epichlorohydrin in the presence of alkali at appropriate experimental conditions. Similarly, benzoxazines (BCP- ffa and BCP-ty) were prepared by reacting with paraformaldehyde and corresponding amines (furfurylamine and tyramine) under suitable experimental conditions.

7. The process of claim 6, wherein the polymerization (curing) temperature of bisphenol CP based epoxy (BCP-Ep) in the presence of varied nature of suitable catalysts studied namely BCP-Ep + ad, BCP-Ep + gu, BCP-Ep + odh BCP-Ep + atu, BCP-Ep + ad + dicy, BCP-Ep + ad + urea, BCP-Ep + tha were found to be 173°C and 240°C, 293°C, 227°C, 274°C, 174°C and 232°C, 175°C and 234°C, 192°C and 231 °C and 185°C and 231 °C respectively.

8. The process of claim 6, wherein the polymerization (curing) temperature of bisphenol CP (BCP) based benzoxazines namely BCP-ffa and BCP-ty were found to be 24l°C and 23l°C respectively. Similarly, the polymerization
(curing) temperature of bisphenol CP (BCP) based benzoxazines in the presence of catalysts studied, the most suitable systems for fabrication of advanced composite components and their working range are BCP-ffa + odh (216°C) and BCP-ty + odh (155, 192°C)

9. The process of claim 6, wherein the thermal stability of cured BCP-Ep in the presence of varied nature of catalysts studied, the highest value of Td was found to be 430°C for cured BCP-Ep + gu. Similarly the highest value of decomposition temperature (Td) was found to be 469°C for poly(BCP-ffa + ad + urea).

10. The process of claim 6, wherein the percentage char yield was calculated from TGA analysis. It was found that the highest value of percentage char yield was found to be 40% for cured BCP-Ep + atu. Similarly the percentage char yield was found to be 46% for poly(BCP-ffa), 58% for poly(BCP-ffa + ad + urea), 37 % for poly(BCP-ty), 47% for poly(BCP-ty + odh + urea).

Dated this 19th Day of October 2024

Signature of the applicant
Dr. N. Saravanakumar
Dr N Saravanakumar
Principal
PSG Institute of Technology aufl
Applied Research
Coimbatvre -641 062.

Documents