US-12624165-B2 - Polyether ketone ketone and a process for preparation thereof

Abstract

A polyether ketone ketone (PEKK) has a terephthaloyl:isophthaloyl (T:I) ratio of 100:0. A process for preparing the PEKK is also provided. The process includes polymerizing 1,4-bis (4-phenoxybenzoyl) benzene (EKKE) with terephthaloyl chloride (TPC), and an end capping agent in a fluid medium, to obtain a product mixture including the PEKK. The PEKK is thermally stable and is melt processable on compounding, for injection molding and extrusion.

Inventors

• Prakash D. Trivedi
• PRAGNESH D. DAMANIA
• Atul R. RAJA

Assignees

• GHARDA CHEMICALS LIMITED

Dates

Publication Date

20260512

Application Date

20201007

Priority Date

20191127

Claims (6)

1. 1 . A process for preparing poly ether ketone ketone (PEKK) with a terephthaloyl (T):isophthaloyl (I) ratio (T:I ratio) of 100:0, said process comprising the following steps: a) adding a Lewis acid to a mixture of 1, 4-bis(4-phenoxybenzoyl) benzene (EKKE) and a first fluid medium, under stirring, and allowing the resultant mixture to exothermically warm to a temperature in the range of 25° C. to 50° C., to obtain a first slurry and stirring said first slurry, for a time period in the range of 0.1 hour to 2 hours; b) polymerizing EKKE in said first slurry, by adding to said first slurry a predetermined amount of terephthaloyl chloride (TPC) and a first predetermined amount of a mixture of at least one end capping agent in a second fluid medium, and stirring the resultant mixture at a temperature in the range of 0° C. to 100° C., for a time period in the range of 0.1 to 6 hours, to obtain a second slurry containing a polymer; c) adding a second predetermined amount of a mixture of said end capping agent and a third fluid medium, to said second slurry, at a temperature in the range of 0 to 100° C., and maintaining temperature for a time period in the range of 2 to 5 hours to obtain a product mixture comprising PEKK; d) quenching said product mixture by adding a methanolic mineral acid, and filtering to obtain crude PEKK solid; e) washing said crude PEKK solid with the methanolic mineral acid, followed by washing with water and a fourth fluid medium to obtain a wet PEKK; and f) drying said wet PEKK under reduced pressure at a temperature in the range of 100° C. to 200° C., to obtain the PEKK wherein the first and second predetermined amount of said end capping agent is in the range of 1 mole % to 14 mole % of the total moles of EKKE; and wherein a mole ratio of said first predetermined amount of said end capping agent to said second predetermined amount of said end capping agent is about 1:2; and wherein the PEKK has: i. a weight average molecular weight in a range of 20,000 to 200,000; ii. thermal stability in a range of 5 to 50%, measured as a change of melt viscosity at 420° C., between 6 and 30 minutes; iii. <0.2% residual volatiles at 270° C.; and iv. a residual metal content of aluminum in a range of 0 to 50 ppm and iron in a range of 0 to 30 ppm.
2. 2 . The process as claimed in claim 1 , wherein said Lewis acid is selected from the group consisting of aluminum chloride (AlCl 3 ) and aluminum bromide (AlBr 3 ).
3. 3 . The process as claimed in claim 1 , wherein said end capping agent is at least one selected from the group consisting of p-chlorobenzoyl chloride (PCBC), benzoyl chloride, EKKE, and their derivatives and mixture thereof.
4. 4 . The process as claimed in claim 1 , wherein said first fluid medium, said second fluid medium, said third fluid medium, and said fourth fluid medium are independently selected from the group consisting of ortho-dichlorobenzene (ODCB), methylene dichloride (DCM), Ethylene dichloride (EDC), monochloro benzene, and a mixture thereof.
5. 5 . The process as claimed in claim 1 , wherein the step (b) of polymerization is carried out at a temperature in the range of 20° C. to 80° C.
6. 6 . The process as claimed in claim 1 , wherein the polymerization time is in the range of 0.5 to 3 hours.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a Section 371 of International Application No. PCT/IB2020/059396, filed Oct. 7, 2020, which was published in the English language on Jun. 3, 2021, under International Publication No. WO 2021/105784 A1, which claims priority under 35 U.S.C. § 119 (b) to Indian Application No. 201921048492, filed Nov. 27, 2019, the disclosures of each of which are incorporated herein by reference. FIELD The present disclosure relates to a Polyether Ketone Ketone (PEKK) and its process for preparation. DEFINITIONS As used in the present disclosure, the following term is generally intended to have the meaning as set forth below, except to the extent that the context in which it is used indicate otherwise. The term “PEKK” as used herein refers to polyether ketone ketone or poly (ether ketone ketone) or polyether (ketone ketone), which is a semi-crystalline thermoplastic polymer of polyaryletherketone (PAEK) family, having high heat resistance, chemical resistance and the ability to withstand high mechanical loads. BACKGROUND The background information herein below relates to the present disclosure but is not necessarily prior art. In oil and gas industry, nuclear industry and aerospace industry, where materials with higher heat resistance and/or chemical resistance are required, it is not possible to use plastics, and as a result metals are used. However, metals have higher specific gravity and require high energy expenditure to form an article. In general, the specific gravity of thermoplastics is ⅓rd to 1/7th of most metals, and thermoplastics can be converted into an article, having intricate shapes, in one or two steps. Besides, thermoplastics can be recycled easily, as compared to recycling of metals, ceramics or even thermosets. Poly ether ketone ketones (PEKKs), which is prepared conventionally using ethylene dichloride (EDC) as solvent, exhibit high glass transition temperature (Tg) and high melting temperature (Tm). Tm of PEKK strongly depends on the ratio between terephthalate (T) isomers, which have para linkages, and isophthalate (I) isomers, which have meta linkages, that is noted as T/I ratio. Presently, poly ether ketone ketones with T:I ratios of 80:20, 70:30 and 60:40 are well-known commercially as high-performance polymers. These PEKKs being semi-crystalline, have a variety of useful properties, such as excellent chemical resistance, electrical insulating and mechanical properties at high temperature, high strength, and toughness and can be used in aeronautics, offshore drilling, and medical/biomedical implants. Further, these polymers may be processed by all the technologies in which thermoplastics are processed, such as injection molding, compression, extrusion, spinning, laser prototyping of filament 3D printing, etc. Polyether ketone ketone polymers may be amorphous or semi-crystalline. However, prior art does not mention PEKK having T:I ratio of 100:0, and does not disclose any method to improve the melt viscosity, and heat stability of PEKK having T:I ratio of 100:0. It has been reported that 1,4-PEKK can be solution processed using solution in concentrated H2SO4. However, the problem is that it is highly corrosive and difficult to handle concentrated H2SO4, as well as the rare possibility of sulfonation of PEKK, thereby destroying its many useful properties, including crystallinity. Further, since the melting temperature of PEKK having T:I ratio of 100:0 is recorded as 389.8° C., it requires a processing temperature of over 400° C., which is undesirable. Hence, PEKKs with T:I ratio of 100:0, that is terephthalate (para linkages) isomers without any isophthalate (meta linkages) isomers, are not commercially produced because they are found to be very unstable, and degrade causing a rapid increase in viscosity at their temperature of processing. Melting point of PEKK with 100% para linkages is close to 395° C., which necessitates a melt processing temperature as high as 410 to 420° C. At such high temperatures, PEKK with T:I 100:0 tends to degrade and gets cross-linked. This makes its melt processing by common plastics processing technologies like injection molding or extrusion nearly impossible. For this reason, PEKK 100:0 is not suitable for industrial applications, which typically require less than 50% change in viscosity over 30 minutes under its processing conditions. This deficiency renders PEKK (with T:I ratio of 100:0) incapable of being used in applications such as medical, general engineering, 3D printing, aerospace, dental implants, etc. Further, it is necessary to have PEKK in a powder form having controlled morphologies, and also have low content of residual reactants, such as un-reacted solvents, un-reacted monomers, catalyst residues or other reaction components or contaminants, such as volatiles, and content of metals such as Al, Fe and Na, in order to minimize their deleterious effects on PEKK stability and color and their depositi