US3425020A - Woven heater - Google Patents

Description

Jan 28,'v 1969 TADAo ToYooKA ETAL 3,425,020

WOVEN HEATER Filed Jan. 23, 1967 INVENTORS TAMO Toyvo/ml :M65/mu. om)

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ATTORNEY? United States Patent O 3,425,020 WOVEN HEATER Tadao Toyooka, Toyonaka-shi, Shigekazu Ota, Yao-shi, and Takeo Nishida, Toyonaka-shi, Japan, assignors to Matsushita Electric Industrial Co., Ltd., Osaka, Japan, a corporation of `lapan Filed Jan. 23, 1967, Ser. No. 610,899 Claims priority, application Japan, Dec. 16, 1966, 41/ 83,419 U.S. Cl. 338-208 9 Claims Int. Cl. H01c 3/00 ABSTRACT F THE DISCLOSURE A woven heater having base woven fabric, lead wires of electro-conductive metallic material interlaced into the fabric base in the areas adjacent to the opposite side edges thereof and extending in the direction of the warp and heating wires each having an electrically insulating yarn Wound thereon and interlaced into the fabric base zigzag to provide good appearance on the faces of the heater and increase its flexibility and mechanical strength.

The present invention relates to woven heaters which are highly flexible and sufficiently strong and have wrinklefree, uniform, and fiat surfaces.

Conventional woven heaters of the type in which an electric heating wire is interlaced into a woven fabric base had the drawback that the appearance of the heater is spoiled by wrinkles or frizzes present in the surfaces thereof. These wrinkles were caused by the fact that, in interlacing the heating wire with warp yarns together with a weft yarn, the heating wire is slackened as the movement 0f a shuttle carrying said heating wire is reversed, thus allowing the latter to swerve from its predetermined state due to the frizzes imparted previously to the heating wire during storage on a spool.

It is, therefore, an object of the present invention to eliminate the aforestated drawback as accompanied by the conventional woven heaters by providing an improved Woven heater which comprises a fabric base woven with warp and weft of electrically insulating fibrous material, electro-conductive metal wires interlaced into said fabric base in the areas adjacent respectively to the opposite side edges thereof and in the direction parallel to said side edges and heating wires each having an electrically insulating yarn Wound thereon and interlaced zigzag into said fabric base along the weft.

It is another object of the present invention to provide a woven heater having a novel construction woven under newly determined Weaving conditions so that the heater is satisfactory in respect of its flexibility and mechanical strength.

According to the present invention, there is provided a woven heater having a woven fabric base woven with a warp consisting of an electrically insulating fiber such as cotton, synthetic fibre or glass fibre and a weft consisting of such electrically insulating material, electroconductive lead wires interlaced into said fabric base in the areas adjacent respectively to the opposite side edges of the web of said fabric base and extending in the direction of the warp, and heating wires each having an electrically insulating yarn wound thereon, said heating wires being interlaced into said fabricV zigzag along the weft in a manner that said heating wires provide a plurality of separate unit heating regions of a predetermined length longitudinally of said woven fabric base, said heating regions being spaced from each other by a zone which is composed only of the warp and weft yarns, said wires being partially raised above the surface of the fabric base 3,425,020 Patented Jan. 28, 1969 lCe at optional locations without interlaced into the fabric base.

According to the present invention, there is also provided a Woven heater which is highly fiexible and sufficiently strong and yet has Wrinkle-free, uniform and fiat surfaces, said woven heater comprising a woven fabric base woven with a warp consisting of an electrically insulating fibrous material such as cotton, synthetic fibre or glass fibre and a weft yarn consisting of such electrically insulating material, electro-conductive lead wires interlaced into said fabric base in the areas adjacent respectively to the opposite side edges of the web of said fabric base and extending in the direction of the warp, and heating wires each having an electrically insulating yarn Wound thereon, said heating wires being interlaced into said fabric base zigzag along the weft, whereby an outer selvage section, a lead wire section comprising said lead wires, an intermediate selvage section, a core wire selvage section and a central core wire section are formed in the order mentioned from the opposite side edges of the woven fabric base towards the center thereof in the direction of the weft, the warp density being from 50 to yarns per centimeter in the outer selvage section, from 30 to 64 wires per centimeter in the lead wire section, from 50 to 100 yarns per centimeter in the intermediate selvage section, from 50 to 100 yarns per centimeter in the core wire selvage section and from l0 to 30 yarns per centimeter in the central core wire section, and the weft density being from 10 to 30 yarns per centimeter.

. The present invention will become more apparent from the following description.

The materials used in the inventive woven heater consist of a filament of synthetic fibre or glass fibre of 100 to 300d as warp, a staple of synthetic fibre or glass fibre of 2.5 to 30's/ l as weft, a stainless steel wire, for example, of SUS27 grade having a diameter of 0.05 to 0.15 mm. as heating wire and a soft copper wire of 0.1 to 0.2 mm. in diameter, for example, as lead wire.

The filament used as the warp is made of a synthetic fibre or glass fibre, such as Tetoron (trade name) or Vinylon (trade name), and has a size of 100 to 300 d., Although filaments of a size smaller than 100 d. may also be weaveable, the smaller the diameter of a filament used, the higher the cost of the resultant product will be, because the filaments should be beaten more densely in order to maintain the shape of the product. On the other hand, the use of a filament of a size greater than 300 d. will result in shrinkage of the product heating element. In this view, it is preferably to use a filament of a size ranging from 100 to 300 d.

The filament used as the warp is twisted from 300 to 500 turns, preferably 450 turns, per meter. The twisted yarn is subjected to steam setting for 10 minutes in a steam atmosphere of 100 C. and then to sizing with a polyvinyl alcohol paste, which is followed by drying. These treatments are conducted for the purpose of preventing the yarn from fiufiing, avoiding shrinkage of the resultant fabric and hardening the yarn to prevent the fabric from losing its shape as a whole. Upon completion of the pretreatment described above, the warp is set in a weaving machine in a predetermined number.

A description will now be given as to the warp densities at various sections of the fabric. The warp density in the respective sections of the fabric must be selected properly in the light of the fact that an excessively high density will render the resultant fabric unsatisfactory in respect of flexibility, while an excessively low density will render the fabric unacceptable in respect of strength. In this view, the warp density in the outer selvage section is from 50 to 100 yarns per centimeter, preferably 8 yarns per 1.5 mm. The width of the outer selvage section is only required to be greater than l mrn. and normally from 1.5 to 4 mm. and preferably 1.5 mm. An excessively narrow width of the outer selvage section is disadvantageous in that the lead wires are pulled inwardly by the weft and cannot be held in a rectilinear state. On the other hand, an excessively large width of the outer selvage section, though not detrimental, is useless unless the section is used for securing the fabric or for other purposes. In this sense, the width of the outer selvage section is limited to about 4 mm. at widest.

Provided inwardly of the outer selvage section is a lead wire section in which soft copper wires serving as lead wire are interlaced with the weft in a number as determined by the amperage used. The lead wires are interlaced at a density of from 30 to 60 wires per centimeter, preferably 37 wires per centimeter. The width of the lead wire section is from 2 to 4 mm., preferably 2.5 mm.

Inside of the lead wire section is provided an intermediate selvage section. This section is provided to ensure insulation between the lead wires and heating wires and the width thereof is preferably at least 5 mm. and may be 20 or 30 mm. in some instances. The warp density in this section is from 50 to 100 yarns per centimeter, which is the same as that in the outer selvage section, and preferably 25 yarns per 5 mm. Normally, it is preferable for the intermediate selvage section to have a warp density 2 to 6 times as high as that in the central core wire section. An excessively low Warp density in this section would result in collapse of the shape of the resultant fabric and also in unsatisfactory insulation between the lead wires and the heating wires as a result of the former being pulled towards the latter, with the distance therebetween reduced. On the other hand, an excessively high warp density in this section would result in hardening of said section causing a wavy shape of the resultant fabric and thus the appearance of the product heating element is spoiled.

Provided inwardly of and adjacent to the intermediate selvage section is a core wire selvage section. This section is provided for the purpose of imparting a portion of the fabric where the heating wires are turned back during the heating wire interlacing operation, with a strength capable of withstanding the tension of said heating Wire. The width of this section is from 3 to mm., preferably 3 mm., while the warp density thereof is from 50 to 100 yarns per centimeter and preferably 60 yarns per centimeter which is sufficient to achieve the purpose described. An excessively low warp density in this section will result in collapse of the shape of the fabric being woven.

Between the opposite core wire selvage sections is provided a central core wire section. The warp density in this section may be as low as from 10 to 30 yarns per centimeter and preferably yarns per centimeter. It is only necessary that the warp yarns at a selected density in this section will not cause loosening of the structure of the woven fabric.

It should be understood that a warp density higher than that specified hereinabove for each section of the woven fabric will only result in increase in material cost and therefore is useless.

The weft as described previously is made of a synthetic fibre or glass bre alike the warp. The yarn consists of a staple which is formed by doubling and twisting a short libre. Before the staple is used in weaving the fabric, the staple is sized with polyvinyl alcohol and dried at 65 C. for 10 hours. The sizing is performed for the purpose of avoiding shrinkage of the resultant fabric and also hardening the fibre so as to prevent collapse of the .shape of the resultant woven fabric as a whole. The size of the weft is determined by the pitch at which the heating Wire is interlaced zigzag and is normally in the range from 10 to 20s. Where the thickness of a product heating element is desired to be reduced, it is obviously necessary to use a weft of a small diameter. When, on the other hand, a thick weft is woven coarsely, the resultant woven heating element becomes thick accordingly, although the cost thereof is reduced.

When the size of the yarn to be used as weft has once been determined with the considerations mentioned above, a suitable weft density can be determined by the pitc'h at which the heating wire is interlaced zigzag. For instance, upon considering the satisfactory insulation between adjacent heating wires, the maximum density oi the heating wires to be interlaced is 12 wires per centimeter. In this case, the weft yarn is to be arranged alternatively with the heating wire and the overall density of the heating wires and weft yarns will be 25 wires and yarns per centimeter.

Referring next to the heating wire, stainless steel of grades up to SUS 27 and of a diameter up to 0.05 to 0.15 mm. are weavable. However, when the heating wire is used as it is, a difficulty is encountered in that the heating wire, during the interlacing operation, is broken due to a frictional heat. This difficulty may be avoided by winding a yarn on the heating wire. For this purpose, a staple same as that used for the weft yarn is used. The size of the yarn is essentially determined by the thickness of the heating wire used. As a standard, a yarn of 15 to 30s is used for a heating wire of 0.1 mm. in diameter and a yarn of 8 to 15s is used for a heating wire of 0.15 mm. in diameter.

Before winding on the heating wire, the yarn is twisted in the direction of Z by 400 to 500 turns per meter. This twisting operation is necessary because normally the staple in its initial state is already twisted in the direction of Z by about 400 turns per meter, so that, if the staple is wound on the heating wire as such, the staple is twisted in the direction of S, that means that the twist originally possessed by the staple is untwisted. If the staple is in untwisted state, an excessive flung is caused during weaving operation and, in some instance, may even be decomposed to such an extent that it is no longer weavable. It is for this reason that the staple is twisted by 400 to 500 turns per meter in the direction of Z before it is wound on the heating wire. Under this state, as will be appreciated, the yarn is twisted by 800 to 900 turns per meter in the direction of Z, including the twist originally imparted to said yarn.

After the yarn in such twisted state is wound on the heating wire by about 470 turns per meter, a twist of a degree just about the same as that originally possessed by the yarn is to be remained in said yarn. In this case, it should be noted that an excessive of the yarn before Winding on the heating wire will result in slippage on the yarn on the surface of the 'heating wire during interlacing operation, with the result that the turns of the yarn are gathered at one place. In this view, the yarn is only required to be twisted by 400 to 500 turns per meter and preferably by 470 turns per meter. An insufficient twisting of the yarn will produce less friction preventive effect, whereas an excessive twisting will cause unsatisfactory contact between the heating wire and lead wires and therefore is not desirable.

In that region of the lead wire section into which the heating wires project in the direction of the weft, the weft yarns and the heating wires are disposed one adjacent to the other alternatively and each of the lead wires extends over and beneath alternatively each one of the successive weft yarns and heating wires thus disposed. In the other portions of the lead wire section wherein no heating wires are interlaced, on the other hand, the lead wires extend in such manner that each of them runs over two or three weft yarns and in turn beneath the following two or three weft yarns and this continues until the next projection of the heating wires is reached.

The latter construction eliminates such drawbacks that the lead wires are apt to be cut or snapped and the lead wire section with this construction is stiff which will be otherwise accompanied by a lead wire section formed entirely with the former construction.

The heating fabric woven into the structure described above is .applied with an electrically-conductive paint, eg. silver paint, at portions where the lead wires Contact the heating wire, in order to ensure satisfactory electrical contact therebetween.

The weft density, as described previously, is determined by the diameter of the heating wire to be interlaced and the size of the yarn to be used as the weft. The maximum density of the heating wires is l2 wires per centimeter, because the density higher than that will result in undesirably less flexibility of the resultant heating fabric. Between the adjacent heating wires is disposed at least one weft. From the standpoint of flexibility and others of the resultant heating fabric, the overall density of the heating wires and weft yarns is preferably not higher than 25 wires and yarns per centimeter. In weaving the heating fabric, it is preferable that the heating wire lhaving the yarn wound thereon is interlaced into the fabric zigzag along the -weft in such a manner that it forms a plurality of separate unit heating regions of a predetermined length, which heating regions are spaced from each other by a zone of fabric which is composed solely of the insulating warp and weft; that the lead wires are partially raised above the surfaces of the woven fabric at optional locations without being interlaced into the fabric; and that the turns of the zigzag heating wire are partially interlaced with or wound on the lead wires on both sides of said zigzag heating Wire.

In order that the present invention `will be better understood and may be readily carried into effect, reference may now be had to the accompanying drawings in which the present invention is illustrated by way of example and in which:

FIGURE l is a diagrammatic plan view of a woven heater according to an embodiment of the present invention and FIGURE 2 is a fragmentary plan view in enlargement of the woven heater shown in FIGURE 1.

Referring to the drawings, there is shown a heating woven fabric 5 which is woven with a warp 1 consisting of a 240 d. filament of Vinylon (trade name) and a weft 3 consisting of a 20s/1 staple of Vinylon and in which lead wires, 2, 2' consisting of a soft copper wire of 0.18 mm. in diameter and heating wires 4 consisting of .a stainless steel wire of SUS 27 grade and of 0.1 mm. in diameter are interlaced, said heating wire `4 having a Vinylon yarn 4 wound thereon at a density of 47() turns per meter. The heating woven fabric 5 is composed of opposite outer selvage sections 6 of 2 mm. in width arranged along opposite side edge portions of said fabric and each cornprising eight warp yarns 1, opposite lead wire sections 7 of 2.5 mm. in width arranged adjacent to said respective outer selvage sections and each comprising sixteen lead wires 2 or 2', opposite intermediate selvage sections 8 of 5 mm. in width arranged adjacent to said respective lead wire sections `and each comprising twenty-five warp yarns 1, opposite core wire selvage sections 9 of 3 mm. in width arranged adjacent to said respective intermediate selvage sections and ea-ch comprising eighteen warp yarns 1, and a central core wire section 10 arranged between said opposite core wire selvage sections 9` and comprising the warp yarns at a density of twenty yarns per centimeter.

The heating wire 4 is interlaced in the fabric at a density of 11 wires per centimeter :and each yweft yarn 3 is disposed between adjacent heating wires 4 and exterior of the outermost heating wires 4, so that the overall density of the heating wires and the weft yarns is 23 wires and yarns in total per centimeter.

The heating wires 4 :are interlaced in the fabric zigzag along the weft yarns in such a manner as to form a plurality of separate unit heating regions which are spaced from each other by a zone 12 of fabric which is composed solely of the warp and weft yarns. The lead wires 2, 2. are partially raised from the surfaces of the woven fabric at optional locations by leaving that portions uninterlaced into said fabric. The opposite turns of the zigzag heating Wires are partially extended outwardly as indicated :at 11, 11 for engagement with or winding `on the respec tive lead wires 2, 2 and silver paint is applied to that engaging portions.

In use of the heat-generating fabric woven in the manner described as a plane heating element, the surfaces of the heat-generating fabric are insulated by embedding said fabric in a synthetic resin by impregnating it with said synthetic resin, or by covering said surfaces with cushion fabrics, such as glass mats or glass cloths, which are heat bonded under pressure to said surfaces from both sides by means of a thermosetting resin impregnated therein; or by covering said surfaces with two sheets of synthetic resin which are attached to said surfaces by means of an adhesive; or by covering said surfaces with thermoplastic resin sheets melt-bonded thereto with heat.

An example wherein the heat generating fabric is used as a plane heating element is provided hereinafter.

A heat-generating fabric obtained in the manner described hereinabove was coated with styrene monomer and embedded in va maleic acid phthalate polyester resin in a manner described below. Namely, two sheets of tempered glass were provided and a releasing agent, such as polyvinyl alcohol, is applied thinly to the shaping surface of one of said sheets of glass. On the layer of the releasing agent was coated a maleic acid phthalate polyester resin and then the surface of said resin coating was sprayed with styrene monomer to eliminate air bubbles present in said resin. When the resin was solidied into a jelly-like state, the heat-generating fabric previously coated with styrene was placed on the jelly-like resin and then the top surface of the styrene-coated fabric was uniformly coated with a small amount of maleic acid phthalate polyester resin and further with styrene to deprive the resin of air bubbles. Thereafter, the other sheet of tempered glass, having a layer of jelly like maleic acid phthalate polyester resin previously formed on a surface thereof in the manner described above, was placed on the fabric with sai-d jelly-like layer facing downwardly so carefully that no air bubble may be trapped therebetween. A pressure of l l g./cm.2 is continuously applied to the top glass until the resin interior of the sheets of glass presented a jelly-like state, `which was followed by heating at 60 to 80 C. for l0 to 20 minutes to thereby cure the resin. After curing, the resin was allowed to cool to about 40 C. and then the sheets of tempered glass were removed, whereupon a product plane heating element was obtained.

The inventive Plane heating element produced in the manner described hereinabove is advantageous in that it is free fro-m wrinkle, because, since the heating wire is interlaced partially in place of the weft yarn, it is not permitted, during the weaving operation, to be slackened as it is turned and to swerve under the swerving tendency previously imparted to said heating wire during storage on a spool.

Another advantage of the inventive plane heating element is that, since the adjacent unit heating regions of a predetermined heating capacity or a predetermined length are optionally spaced from each other by a zone of fabric which is composed solely of the insulating warp and weft yarns, not only is it possible to obtain la positive insulation between the heating Wires in said unit heating regions but also each heating region can be sepanated from another easily by cutting. In addition, when holes are required to be bored at a portion of the inventive heating element for ventilation or for other purposes, such holes can be provided in the nonheat-generating zone of the fabric formed between #adjacent unit heating regions. Still another advantage of the 4heating element is that the heating wires in the respective unit heating regions may be connected in series or in parallel by cutting the portions of the lead wires which are raised or projected above the surfaces of the woven fabric in the shape of an larch at optional locations and such an ladvantageous eifect of the invention niay be further enhanced by the arrangement in which a plurality of unit heating regions Iare provided in the heating element as described previously for separation frolm one another. The inventive heating element has a high flexibility and a suiiicient strength owing to the structure defined hereinabove numerically. Furthermore, since the surfaces of the inventive heating element are covered with `a material such as synthetic resin, the heating element itself is not subjected to secular variation and has a good feeling to the human skin when used as a heating appliance.

What is claimed is:

1. A woven heater comprising a woven fabric base woven with a Warp consisting of an electrically insulating fibrous material and a weft consisting of such electrically insulating fibrous material, electroconductive lead wires interlaced into said fabric base in the areas 'adjacent respectively to the opposite side edges of the fabric base and extending in the direction of the warp, and heating wires each having 'an electrically insulating yarn Wound thereon, said heating wires being interlaced into said fabric base zigzag along the weft in a manner that said heating wires provide a plurality of separate unit heating regions of a predetermined length longitudinally of said woven fabric base, said heating regions being spaced from ea'ch other by la zone of fabric which is composed solely of Warp and weft yarns, said lead wires being partially raised above the surface of the fabric at optional locations without being interlaced into the fabric, there being an outer selvage section, a lead wire section comprising said lead wires, an intermediate selvage section, a core Wire selvage section and a central core wire section in the order mentioned from the opposite side edges of the woven fabric towards the center thereof in the direction of weft, warp density being from substantially 50 to substantially 100 yarns per centimeter in the outer selvage section, from substantially 30 to substantially 64 wires per centimeter in the lead wire section, from substantially 50 to substantially l0() yarns per centimeter in the intermediate selvage section, from substantially 50 to substantially 100 yarns per centimeter in the core wire selvage section and from substantially 10 to substantially 30 yarns per centimeter in the central core wire section, and the weft density being fro'm substantially 10 to sub* stantially 30 yarns per centimeter.

2. A woven heater according to claim 1, wherein the intermediate selvage section has a warp density of from about 2 to about 6 times the warp density of the central core section.

3. A woven heater according to claim 1, wherein the warp density of the outer selvage section is substantially 8 yarns per 1.5 millimeters, of the lead Wire section is substantially 37 wires per centimeter, of the intermediate selvage section is substantially yarns per millimeter, of the core wire selvage section is substantially 60 yarns per centimeter and of the core wire section is substantially 20 yarns per centimeter.

4. A Woven heater according to claim 1, wherein the width of the outer selvage section is from substantially 1 millimeter to substantially 4 millimeters, of the lead wire section is frolm substantially 2 millimeters to substantially 2.5 millimeters, of the intermediate selvage section is from substantially 5 millimeters to substantially 30 millimeters, and of the core Wire selvage section from substantially 3 millimeters to substantially 10 millimeters.

5. A woven heater according to claim 2, wherein the width of the outer selvage section is from s-ubstantially 1 millimeter to substantially 4 millimeters, of the lead wire section is from substantially 2 millimeters to substantially 2.5 millimeters, of the intermediate selvage section is from substantially 5 millimeters to substantially 30 millimeters, and of the core wire selvage section from substantially 3 millimeters -to substantially l0 millimeters.

6. A woven heater according to claim 3, wherein the width of the outer selvage section is from substantially l millimeter to substantially 4 millimeters, of the lead wire section is from substantially 2 millimeters to substantially 2.5 millimeters, of the intermediate selvage section is from substantially 5 millimeters to substantially 30 millimeters and of the core wire selvage section from substantially 3 millimeters to substantially l0 millimeters.

7. A Woven he-ater according to claim 4, wherein the width of the outer selvage section is substantially 1.5 millimeters, of the lead wire section is substantially 2.5 millimeters, of the intermediate selvage section is substantially 5 millimeters, and of the core wire selvage section is substantially 3 millimeters.

8. A woven heater according to claim 5, wherein the Width of the outer selvage section is substantially 1.5 millimeters, of the lead wire ysection is substantially 2.5 millimeters, of the intermediate selvage section is substantially 5 millimeters, and of the core wire selvage section is substantially 3 millimeters.

9. A woven heater according to claim 6, wherein the width of the outer selvage section is substantially 1.5 millimeters, of the lead wire section is substantially 2.5 millimeters, of the intermediate selvage section is substantially 5 millimeters, and of the core wire selvage section is substantially 3 millimeters.

References Cited UNITED STATES PATENTS 1,703,005 2/1929 Hewitt 219-545 X 2,375,997 5/1945 Larson 219-545 2,812,409 11/1957 Jones et al 338-208 X 3,290,807 12/1966 Esaka 219--545 BERNARD A. GILHEANY, Primaly Examiner. VOLODYMYR Y. MAYEWSKY, Assistant Examiner.

U.S. Cl. XR. 219--529, 545, 549

mg?) UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,425,020 Dated January 28l 1968 Inventgds) Tadao Toyooka et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

,CQlumn l, line 65 -base should be inserted after "fabric". Column 2, line l being should be inserted after "without"; line 43 --preferably 240d.- should be inserted after "30061., line 50 "preferably" should read preferable. Column 6, lines l and 5, "that" Should read -those-; line 7l, inventive should be inserted after "the" (first occurrence).

SIGNED AND SEALED JUL 211970 SEAL) Attest:

Edwr" M- FM wrmrm E. somrm, JR. Anesting Office: M of Patents

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