Abstract A hair curler employing a heater element formed of a conductive crystalline polymer is disclosed. The polymer, loaded with conductive particles, such as carbon black, has a positive temperature coefficient (PTC) of resistivity characteristic and combines a fast warm-up time with a slow cool down time due to the phase change of amorphous polymer to crystalline polymer upon cooling. The heat of fusion curve of the crystalline polymer is related to the temperature versus resistivity curve such that a sharp rise in resistance above an anomaly temperature and in and around the operating temperature of the curler limits the heat generation and prevents some of the crystalline polymer from changing state and maintains the structural integrity of the polymer. Since the polymer retains its shape, no special sealing means is required to confine it as in fusible wax devices. Means are disclosed to make electrical contact to the heater element and for mounting it within an outer hair curler shell.
Inventors
👤 John V Meyer
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-25 20:52
CPC Classifications
A; A45; A45D; A45D2/00; A45D2/36
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
15 words
A hair curler according to claim 1 in which the conductive filler is carbon black.
Claim 2
Dependent Claim
47 words
A hair curler according to claim 1 in which upon sufficient heating of the hair curler the electrical resistance of the element increases several orders of magnitude, most of the increase occurring prior to the phase change of most of the crystalline polymer regions to amorphous polymer.
Claim 3
Dependent Claim
15 words
A hair curler according to claim 1 in which the polymer is a crystalline polyolefin.
Claim 4
Dependent Claim
16 words
A hair curler according to claim 2 in which the polymer is a copolymer of polyethylene.
Claim 5
Dependent Claim
38 words
A hair curler according to claim 1 in which the polymer is a high density polyethylene. 7 A hair curler according to claim 2 in which the carbon black comprises 14- 20 percent by weight of the element.
Claim 6
Dependent Claim
14 words
A hair curler according to claim 1 in which the polymer is a polypropylene.
Claim 7
Dependent Claim
18 words
A hair curler according to claim 1 in which the warm up time is less than 5 minutes.
Claim 8
Dependent Claim
149 words
An electrically heated device comprising an element which serves both as a heater and as a heat storage means, the element composed of crystalline polymer filled with 14- 20 percent by weight of carbon particles and having a positive temperature coefficient of resistance, the element having a first relatively low resistance mode at ambient room temperature and a second high resistance mode at an operating temperature, the element having a heat of fusion curve such that heat is stored in the element as crystalline regions change to the amorphous state, the second high resistance mode limiting the temperature rise of the element before all the crystalline polymer changes state whereby the structural integrity of the element is maintained yet permitting latent heat of fusion to be used to keep the device warm for an extended period of time after deenergization, and means for making electrical connection with the element.
Claim 9
Dependent Claim
50 words
An electrically heated device according to claim 10 in which the element is in the form of an elongated annulus and further including A generally cylindrical outer shell, a plurality of fingers extending outwardly from the shell, and the element located within the shell in good heat transfer relation therewith