EP-4735498-A1 - SEMI-RIGID POLYURETHANE POTTANT COMPOSITIONS AND METHODS FOR PREPARING SAME

Abstract

Polyurethane compositions include a reaction product of: an isocyanate component comprising one or more isocyanate compounds; and an isocyanate-reactive component including: one or more polyether polyols comprising at least one capped polyether polyol having an OH functionality of 3 to 6, and an EO content of 10 wt%to 25 wt%; one or more polyol crosslinkers having a hydroxyl functionality of 2 or more; and one or more solid flame resistance (FR) additives in at least one of the isocyanate component, the isocyanate-reactive component, or a third component; wherein the polyurethane composition has a hardness of 20 Shore A or more. Methods include preparing polyurethane compositions that include combining the isocyanate component and the isocyanate-reactive component to form a mixture; and reacting the mixture to form the polyurethane composition.

Inventors

• ZHANG, Degang
• FENG, Yanli
• ZHANG, PING

Assignees

• Dow Global Technologies LLC

Dates

Publication Date

20260506

Application Date

20230630

Claims (10)

1. A polyurethane composition, comprising a reaction product of: an isocyanate component comprising one or more isocyanate compounds; and an isocyanate-reactive component comprising: one or more polyether polyols comprising at least one capped polyether polyol having an OH functionality of 3 to 6, and an EO content of 10 wt%to 25 wt%; one or more polyol crosslinkers having a hydroxyl functionality of 2 or more; and one or more solid flame resistance (FR) additives in at least one of the isocyanate component, the isocyanate-reactive component, or a third component; wherein the polyurethane composition has a hardness of 20 Shore A or more.
2. The composition of claim 1, wherein the solid FR additive is present at a percent by weight of the total composition (wt%) ranging from 5 wt%to 35 wt%.
3. The composition of claim 1, wherein the FR additive is one or more of expandable graphite, aluminum hypophosphite, and ammonium polyphosphate.
4. The composition of claim 1, further comprising a blowing agent.
5. The composition of claim 1, further comprising a silicone surfactant.
6. The composition of claim 1, wherein the one or more polyol crosslinker has a hydroxyl number in a range of 400 mg KOH/g to 2500 mg KOH/g.
7. The composition of claim 1, wherein the one or more polyol crosslinkers are present at a percent by weight (wt%) of the isocyanate-reactive components of 1 wt%to 25 wt%
8. The composition of claim 1, wherein the polyurethane composition has a density according to ASTM D3574-17 in a range of 0.2 g/L to 130 g/L.
9. A pottant prepared from the polyurethane composition of any one of claims 1 to 8.
10. A method of preparing the polyurethane composition of claim 1, comprising: combining the isocyanate component and the isocyanate-reactive component to form a mixture; and reacting the mixture to form the polyurethane composition.

Description

SEMI-RIGID POLYURETHANE POTTANT COMPOSITIONS AND METHODS FOR PREPARING SAME FIELD Embodiments relate to flame resistant polyurethane compositions, methods for preparing and applications utilizing same. BACKGROUND Electric vehicles (EV) operate with a battery pack and the individual cells are arranged in different patterns along with cooling mechanism related components and other parts in the vicinity. Battery cell geometry can take on many forms including cylindrical, rectangular/prismatic, pouch, and combinations that are layered and organized to increase energy density. Gaps between battery elements are filled with a pottant material (usually polyurethane or silicone) , which isolates battery cells thermally and augments battery assembly strength under various use conditions such as vibration, high temperature and high humidity. Polyurethane-based foams are often employed in the automotive industry as pottants to reduce weight to improve efficiency and handling. However, PU-based pottant materials should be strong enough to bond the batteries cells together and resistant to heat and open flame, and there are often performance tradeoffs with less dense foam materials. In order to meet the flame resistance requirements of the industry, various standards are applied to quantify flammability of plastics, such as the Standard for Safety of Flammability of Plastic Materials UL 94. To achieve desired fire performance, standard flame resistance (FR) additives are applied to pottant formulations in relatively large amounts, which can affect physical properties such as modulus and hardness. For example, liquid FR additives such as phosphate esters often make up substantial percentages of the formulation weight (e.g., 15 wt%to 60 wt%or more) , which impacts foaming balance during polyurethane formation and ultimately foam quality and density. Liquid FR additives may also function as a plasticizer, and significantly alter the physical properties of a foam under high temperature. SUMMARY Embodiments disclosed herein include polyurethane compositions, including a reaction product of: an isocyanate component comprising one or more isocyanate compounds; and an isocyanate-reactive component including: one or more polyether polyols comprising at least one capped polyether polyol having an OH functionality of 3 to 6, and an EO content of 10 wt%to 25 wt%; one or more polyol crosslinkers having a hydroxyl functionality of 2 or more; and one or more solid flame resistance (FR) additives in at least one of the isocyanate component, the  isocyanate-reactive component, or a third component; wherein the polyurethane composition has a hardness of 20 Shore A or more. DETAILED DESCRIPTION Embodiments relate to polyurethane foams and compositions having flame resistant properties, and suitable for generating semi-rigid potting and thermally insulating materials. Embodiments relate to polyurethane (PU) compositions for pottant and electronic materials having an isocyanate-reactive component that includes a mixture of polyether polyol, polyol crosslinker, solid flame resistance (FR) additive, and other additives. PU compositions may be semi-rigid (i.e., Shore A hardness greater than 20) and may produce foams suitable for use as pottants having a flammability rating according to UL-94 of V1 or better, and low thermal conductivity (＜0.10 W/m*K) . Compositions disclosed herein include two-part polyurethane compositions for use as pottants and encapsulants useful in a number of electronics and electric vehicle (EV) battery applications. PU compositions are formulated with solid FR additives that have improved properties when compared with polyurethanes formulated with liquid FR additives that negatively affect physical strength, particularly at elevated temperatures. Articles and pottants prepared according to the present disclosure may exhibit a UL-94 vertical burn rating of V1 or better and ≤0.1 W/m*K thermal conductivity, while also maintaining high temperature strength (i.e., elongation at break ≥10%, hardness and storage modulus retention ≥60%) . PU compositions disclosed herein generally include the product obtained from combining a two-component curable composition: an isocyanate component ( “A-side” ) and an isocyanate-reactive component ( “B-side” ) . During application, the isocyanate and isocyanate-reactive components are mixed, initiating a curing reaction, and forming a polyurethane article or material. PU compositions may also include one or more solid FR additives added to the isocyanate and/or isocyanate-reactive components, or as a third component added during mixing. Isocyanate components may contain one or more isocyanate compounds, such as polymeric isocyanates, aromatic isocyanates, or carbodiimide-modified isocyanates. Isocyanate compounds may be monomeric, oligomeric, prepolymers, and the like. The isocyanate component can include, for example, one or more isocyanate and/or polyisocyanate compounds. Isocyanat