PPTC composition and device having low switch temperature and sharp crystallization behavior

Patent metadata

Field	Value
Publication number	US-10902983-B2
Application number	US-202016941920-A
Country	US
Kind code	B2
Filing date	Jul 29, 2020
Priority date	Jan 20, 2019
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

A PPTC device is provided. The PPTC device may include a first electrode and a second electrode, disposed opposite the first electrode. The PPTC device may include a PPTC layer, disposed between the first electrode and the second electrode, the PPTC layer comprising a polymer matrix formed from a thermoplastic polyurethane (TPU) material.

First claim

What is claimed is:

1. A method of forming a PPTC device, comprising:
forming a polymer matrix material, based upon a polycaprolactone material or a thermoplastic polyurethane (TPU) material;
dissolving the polymer matrix material in a solvent to form a polymer mixture;
mixing a conductive filler into the polymer mixture to form an ink;
applying the ink to a substrate;
maintaining the substrate at room temperature for a duration of at least 30 minutes, whereby a first portion of the solvent is evaporated; and
heating the substrate to a temperature of 60° C. to 150° C., whereby a second portion of the solvent is evaporated.

2. The method of claim 1 , the applying comprising: performing a direct liquid dispense, screen printing, stencil printing, or ink jet printing.

3. The method of claim 1 , wherein the solvent comprises xylene, mesitylene or anisole, having a weight percent of up to 80 wt %.

4. The method of claim 1 , further comprising exposing the ink to an alcohol additive.

5. The method of claim 1 , further comprising: before the mixing the conductive filler, mixing the polymer matrix material with the solvent using a speed mixer, a rolling mixer, or a sonification tool, at a mix temperature between room temperature and 80° C.

6. The method of claim 1 , further comprising exposing the ink to a radiation beam, wherein a portion of the polymer matrix material is crosslinked.

7. The method of claim 1 , wherein the polymer matrix material comprises units derived from diisocyanate, a bio-based polyol, and chain extender diol.

Assignees

• Littelfuse Inc

Inventors

• Rutter Jr Edward W
• Matus Yuriy B
• Pineda Martin

Classifications

• C09D11/104

  Polyesters · CPC title

• C09D11/03

  characterised by features other than the chemical nature of the binder · CPC title

• C09D11/36

  based on non-aqueous solvents · CPC title

• C09D11/52 Primary

  Electrically conductive inks · CPC title

• C09D11/102

  containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds · CPC title