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US-12624160-B2 - Liquid crystal polymer compositions, articles and methods of making

US12624160B2US 12624160 B2US12624160 B2US 12624160B2US-12624160-B2

Abstract

Described herein are polymer compositions including at least 20 wt. % of a liquid crystal polymer (“LCP”); 10 wt. % to 40 wt. % of a flat glass fiber and 15 wt. % to 50 wt. % of boron nitride and/or zinc oxide. It was surprisingly discovered that polymer compositions including an LCP in conjunction with a combination of flat glass fibers and boron nitride and/or zinc oxide had improved thermal conductivity and flexural properties, relative to analogous polymer compositions having round glass fibers in place of the flat glass fibers.

Inventors

  • Emmanuel Anim-Danso

Assignees

  • SYENSQO SPECIALTY POLYMERS USA, LLC

Dates

Publication Date
20260512
Application Date
20211021
Priority Date
20210108

Claims (8)

  1. 1 . A polymer composition consisting of: at least 20 wt. % and at most 60 wt. %, based on the total weight of the polymer composition, of a liquid crystal polymer formed from the polycondensation of the following monomers: terephthalic acid, 4,4′-biphenol, isophthalic acid, and 4-hydroxybenzoic acid; from 10 wt. % to 40 wt. %, based on the total weight of the polymer composition, of a flat glass fiber; and boron nitride and zinc oxide, wherein the total concentration of boron nitride and zinc oxide is from 15 wt. % to 50 wt. %, based on the total weight of the polymer composition; optionally an additive selected from the group consisting of tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, nucleating agents, and antioxidants; wherein the relative concentration of boron nitride to zinc oxide expressed as weight of boron nitride in the polymer composition/weight of zinc oxide in the polymer composition is from 0.5 to 2, wherein the flat glass fiber is E-glass fiber and the composition is free of additional glass fibers; wherein the flat glass fiber has an aspect ratio of at least 2 and at most 8; wherein the flat glass fiber has an average length of from 3 mm to 50 mm wherein the average length is the average length of the glass fiber prior to incorporation into the polymer composition or the average length of the glass fiber in the polymer composition; and wherein the composition has an apparent viscosity from 90 Pa.s to 300 Pa.s at a shear rate of 100 s-1, as measured according to ASTM D3835.
  2. 2 . The polymer composition of claim 1 , wherein the polymer composition has a through-plane thermal conductivity of from 0.20 W/m-K to 0.9 W/m-k, as measured by Laser Flash according to ASTM E1461-13.
  3. 3 . The polymer composition of claim 1 , wherein the polymer composition has a flexural strength of from 100 MPa to 250 MPa, according to ASTM D790.
  4. 4 . The polymer composition of claim 1 , wherein the polymer composition has a flexural strain of from 100 MPa to 190 MPa, as measured according to ASTM D790.
  5. 5 . The polymer composition of claim 1 , wherein polymer composition has an apparent viscosity of from 35 Pa.s to 150 Pa.s at a shear rate of 500 s −1 ; or of from 25 Pa.s to 100 Pa.s at a shear rate of 1000 s −1 ; as measured according to ASTM D3835.
  6. 6 . The polymer composition of claim 1 , wherein the concentration of the flat glass fiber is from 10 wt. % to 30 wt. %, based on the total weight of the polymer composition.
  7. 7 . The polymer composition of claim 1 , wherein the glass fiber has an aspect ratio, defined as the average ratio between the length and the largest of the width and thickness, of at least 5.
  8. 8 . The polymer composition of claim 1 , wherein the additive is selected from the group consisting of tougheners, plasticizers, colorants, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, nucleating agents, and antioxidants.

Description

RELATED APPLICATIONS This application is a national stage entry under 35 U.S.C. § 371 of International Application No. PCT/EP2021/079214 filed Oct. 21, 2021, which claims priority to U.S. application Ser. No. 63/105,416 filed on Oct. 26, 2020 and to European Application No. 21150658.9 filed on Jan. 8, 2021. The entire contents of these applications are explicitly incorporated herein by this reference. FIELD Polymer compositions are provided. The polymer compositions have excellent thermal conductivity and include a liquid crystal polymer (“LCP”), a flat glass fiber, and either or both of boron nitride and zinc oxide. Articles incorporating the polymer compositions as well as methods of making the polymer composition and articles are also provided. BACKGROUND As the power density of electrical components increases, so does thermal output of the electrical component, at least in part due to the resistance of the current carriers. The result is significantly increased heat accumulation in the electrical component. For example, there is a continuous demand to increase the power density in electric motors for electric vehicles (e.g. automobiles, motorcycles, boats and planes), concomitant with increasing consumer demand for higher performing vehicles. However, as power density increases, so does the heat accumulation in and around the electric motor, which can significantly reduce motor efficiency. SUMMARY In a first aspect, a polymer composition is provided that includes a liquid crystal polymer (“LCP”) formed from the polycondensation of the following monomers: terephthalic acid, an aromatic diol, a first aromatic dicarboxylic acid, an aromatic hydrocarboxylic acid; 10 wt. % to 40 wt. % of a flat glass fiber; and boron nitride and/or zinc oxide, wherein the total concentration of boron nitride and zinc oxide is 15 wt. % to 50 wt. %. In some embodiments, the aromatic diol is 4,4′-biphenol, the aromatic hydrocarboxylic acid is 4-hydroxybenzoic acid, and the first aromatic dicarboxylic acid is isophthalic acid. In some embodiments, the polymer composition is free of zinc oxide. In some embodiments, the polymer composition is free of boron nitride. In some embodiments, the polymer composition includes boron nitride and zinc oxide. In one such embodiment, the relative concentration of boron nitride to zinc oxide is from 0.5 to 2. In some embodiments, the polymer composition has a through-plane thermal conductivity of from 0.20 W/m-K to 0.9 W/m-k, as measured according to ASTM E1461-13. In some embodiments, the polymer composition has a flexural strength of from 100 MPa to 250 MP, according to ASTM D790. In some embodiments, the polymer composition has a flexural strain of from 100 MPa to 190 MPa, as measured according to ASTM D790. In some embodiments, the polymer composition has an apparent viscosity of from 90 Pa·s to 300 Pa·s at shear rate of 100 s−1; from 35 Pa·s to 150 Pa·s at a shear rate of 500 s−1; or of from 25 Pa·s to 100 Pa·s at a shear rate of 1000 s−1, as measured according to ASTM D3835. In some embodiments, the polymer composition is free of round glass fibers. In another aspect, an article comprising the polymer composition is provided, wherein the article is an electrical component. In some embodiments, the article is an electric motor component. In some embodiments, the article is a slot liner. In some embodiments, the article is selected from the group consisting of automotive components, aerospace components and watercraft components. DETAILED DESCRIPTION Described herein are polymer compositions including at least 20 wt. % of a liquid crystal polymer (“LCP”); 10 wt. % to 40 wt. % of a flat glass fiber and 15 wt. % to 50 wt. % of boron nitride and/or zinc oxide. It was surprisingly discovered that polymer compositions including an LCP in conjunction with a combination of flat glass fibers and boron nitride and/or zinc oxide had improved thermal conductivity and flexural properties, relative to analogous polymer compositions having round glass fibers in place of the flat glass fibers. As used herein, weight percent (“wt. %”) is relative to the total weight of the polymer composition, unless explicitly stated otherwise. Any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure; where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list; and any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges a