DE1540949A1 - Novel product - Google Patents

Description

The invention relates to new products and on processes for their production. Aimed in giner terms they are on electrically conductive fibrous (fibrous *?) webs and the "purulent" still on essentially insoluble, electrically conductive types of paper, the high carbon ones endless construction. Take up single or slement threads, and on heating elements or bodies constructed from them

Even if different types of electrical heating elements or bodies have been developed, they still emerge fell «problem with the finished of a hat or train that sat Uniform heat generation over a large surface area is due, which means that spots (spots) are avoided are due to irregular · resistance fluctuations and local * overshoots. Chemicals impregnated and encased »

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1540949 wires and powders are by no means a satisfactory solution to these problems. Expensive hot plates and panels that have consistent electrical as well as physical properties such as flexibility, color, physical strength, have been the subject of extensive research. Electrically conductive sheets and papers have also been used extensively in radio image reproduction, a conductive paper coated with various suitable materials being provided with a designed image when an electric current is passed through a stylus. Perhaps the most common conductive paper has a base sheet (base sheet) of cellulose fibers impregnated or filled with carbon particles and coated with an electro-sensitive material. Such carbon powder-coated papers and their manufacture are vividly described in U.S. Patents 3,012,928 and 3,022,213. The entrainment of clay particles in the sheets or sheets for imparting electrical conductivity has many disadvantages The main disadvantage was the extremely high level of coating τοη carbon paper, which was necessary to achieve τοη sheet-sheet resistance values below 60 01m per approx zui forming ion Schertzflecken etc.) usually Inferior is, the density of the sheets "hook and its porosity low" Although adding to a higher electrical conductivity

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with less weighting of finely divided conductive particles may occur, the composition of the web or matrix in which conductive particles are incorporated, e.g. $ 5-100 of a synthetic polymer binder like this is critical in U.S. Patent 2,993,816.

The aim of the invention is to create an electrically conductive fibrous sheet, the electrically conductive granules or granular materials not required

Another goal is also to create a practical one non-meltable electrically conductive paper that has good physical or mechanical properties and not necessarily is dark in color.

The invention also aims to provide an electrically conductive path that is not noticeable in terms of its electrical conductivity at different relative ■ Humidity conditions or with continuous bending of the web varies,

Another object of the invention is to provide an electric conductive sheet of high porosity and low density.

Another aim of the invention is to create a novel electrical heating element (component).

The aim of the invention is also to create a simple one and economical operation for the production of the aforementioned electrically conductive tracks.

It has thus been found that a substantially infusible, nonwoven, fibrous web containing at least 50 wt. at essentially evenly distributed, electrically conductive,

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high-carbon or carbon-containing single or Has filaments, the above and other advantages created, provided that the carbonaceous (continuous) filaments an average fiber length of 1.6 to 11.11 mm and an average denier of 0.25-5 (preferably about 0.4 to 1), the filament length about ten times the thread diameter. It was also found that such electrically conductive tracks on a conventional Paper making machine manufacture and that the specific electrical resistivity at values between about 0.036 and 60 ohms per cm can be maintained. The ease of dispersibility of the high carbon fibers in aqueous slurries, particularly wood or other cellulosic pulp slurries, is exceptional because of the difference in density between such conductive fibers and wood fiber material small and fiber segregation (segregation) to a minimum amount is reduced.

The main fibrous components, which are at least 50 wt .- ^ of the nonwoven web are practically infusible and can be of synthetic or natural origin. For Manufactured on a paper machine using conventional processes, the nonwoven web can be made from a aqueous suspension of infusible organic or inorganic fibers with papermaking properties to which Cellulose, cellulose derivatives, asbestos, asbestos-glass mixtures, "90 9884/0785

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Asbestos-cellulose mixtures, cellulose-glass mixtures, etc. Other infusible staple fibers and fillers, for example metal threads and flakes, mica flakes, thermosetting resins, titanium dioxide, zinc oxide, can also be used. You can also take with you smaller amounts of material that can be melted in the fawn, for example fibrids that do not change the fundamental infusibility of the structure. Although one can, in general, preferably, the conductive carbonaceous (-containing) threads in an insulative nichtge- woven matrix bring the electrical properties of the plate or panel may be modified for specific purposes by the inclusion of other conductive materials, usually in a lesser amount in comparison to those ah conductive carbon-containing slement threads. It is particularly preferred to use a cellulosic papermaking pulp as the main component of these conductive paths.

Electrically conductive, high-carbon (£ 1βα-η-tar-) threads (ie lit 80 * carbon, preferably over 90 * carbon) are well known. In an operation of heating for their preparation fibers »it high cellulose content in the absence of Sau" · toff and humidity in a temperature range of about 149 to 816 ⁰ O Ua sue conclusion practically complete carbonation and continue sttst the material to a temperature above atf * 816 ⁰ O to long enough that ta electrical! • ittnd is valid . The "ltftoft * is on the USA-F" tent 3 011 tu entnahaan · To "inis other proceedings ensgaog, which in de"

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US-patent is described in 3,107,152, the heating of a material ever heard based on cellulose at a rate of about iO ° C-temperature rise hrs. To about 50 ° C temperature rise per hr., Starting from an initial temperature τοη about 100 ⁰ C MS 400 ⁰ C, followed by a heating rate of up to 10O ⁰ C per hour to a final temperature of about 900 ⁰ C, followed by further heating until the most extensive graphitization occurs. Other carbonization operations are described in US Pat. No. 3,071,637. The high-carbon ropes, silk ropes, fibers, (continuous) egg filaments or fabrics with a denier value of 0.5 to 5 produced in the above manner are beaten or chipped to an average fiber length of 1.587 - 11.112 mm (1 / 16- 7/16 inch), preferably 0.125 to 0.375 U ₉ . If the average fiber length falls below this lower limit, then the inherent resistance of the web increases with constant loading Berklich, whereas average fiber lengths above the maximum value are difficult to handle and can be (homogeneously) mixed with other fibers and also tend to form plates or to guide tracks which have irregular resistance properties on the production part and the production part. In the range of appropriate denier values, a slight increase in conductivity can be achieved in oil-filled deniers with the same weights! veaus can be achieved.

Although the electrically conductive, carbon dioxide-containing Eleaentar threads are relatively brittle, they have

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sufficient flexibility to withstand normal bending of the porous web or paper in which they are incorporated and does not otherwise necessarily adversely affect the other desirable physical properties of the finished sheet or plate within the stated maximum load values less than about 1Jt or more than about 1/35 ^ of the carbon-containing filaments are used, the resistance control extremely difficult

FIG. 1 illustrates the lower resistance which was obtained in a wood pulp paper with carbonaceous 6.550 mm elementary filaments (with about 90% by weight carbon) compared to the same NiT from a 60% carbon powder coating. It can be seen that a paper with a weight on 6O96 carbon powder (Conductei) corresponded in terms of its resistance to a paper containing about 4% carbon-containing filaments, the latter having the additional advantage of high porosity, lighter color and better handling properties. Generally requires a usual, weighted with carbon pulver paper an about 50 to Over 100 # carbon weighting in order to achieve values with a specific resistance comparable to the conductive ones Webs according to the invention; and such sheets or webs smear and lose carbon at the higher load values. Likewise, the incorporation of metal flakes into a sheet of paper requires over about 50 pounds of weight before

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a significant change in resistivity is achieved; and both metal flakes and metal fibers the tend to increase the sheet density and decrease the sheet porosity. Due to the oxidation of certain metals, such as aluminum and copper, papers that can rely on Metal flakes or threads, which vary considerably in specific resistance over a long period of time. In addition, it has been found that it is difficult to disperse metal filaments in a pulp slurry and that they impart some undesirable properties to the arch such as stiffness, etc.

FIG. 2 shows the variation in terms of specific resistance when a load is created with carbon-containing 6.350 mm fibers (90% by weight carbon). Control of the resistance of these carbon fibers is achieved one with 3-35 wt. ^ of the carbonaceous fibers, whereby the range of 4 - 303 * is preferred.

FIG. 3 illustrates the relationship between the fiber length and the specific resistance in a paper with a 5% weighting of carbon-containing filaments (about 90 wt .- ^ carbon). Adequate resistance control requires an average fiber length of 1.587-11.112 mm (1/16 - 7/16 inch), preferably 3.175-9.525 mm.

From the above it can be seen that, within the specified limits, the final sheet's resilience, as well as its color and physical properties, are important.

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carefully controlled «. By varying the basis weight (4.5-45.4 kg per 278.7 m ² ream) and the bulkiness or porosity of the arch or sheet ·. 30 - 70 degrees Schopper-Riegler freeness J, as well as the physical properties of the other fibers and fillers used, you can even achieve a further regulation

Example 1

A high-carbon, electrically conductive fabric, prepared according to the previously described graphing processes, was cut into 7.62 cm square pieces and washed with water in a scraping or dividing device dispersed, these Treatment was continued until the fabric became fibers was crushed with an average length of about 3.175 mm These carbonaceous fibers (about 90 pounds of carbon) were made then uniformly in an aqueous slurry from a pulp dispersed in a storage chest to give a 9 # weighting of the conductive fibers, with the remainder being pulped. This slurry was added to the top box a 22.86 cm paper machine for the papermaking operation added, the paper machine having a 0.177 mm (80 mesh) opening wire screen and during the Operating procedure the test device was kept between 5 and 6 units · The resistivity of that obtained Paper was 0.540 ohms / cm, measured with a Wheatstone bridge,

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Example 2

High carbon containing electrically conductive fibers (6,350 mm in length, 0.4 denier, 99 _t 9 # carbon) were dispersed in an aqueous slurry as solids 60.6 wt. «I» asbestos fiber material (quality for papermaking), 12 parts by weight 3 * glass microfibers (6.350 mm length) and 24 wt .- ^ of a powdered, fusible phenol-formaldehyde resin, with the carbonaceous fibers 3 »4 wt .- ^ τοη the total solids · Using a 25.4: 30.48 cm - Williams hand sheet expeller having a screen with an opening of 0.177 mm, a sheet (plate) was formed and dried. The resulting paper had a thickness of 0.1651 mm and an intrinsic resistance τοη 0.975 Ohm / cm.If electrical contacts are bridged with this arc and the voltage is regulated to provide sufficient heating to cause the phenol powder to melt, the intrinsic resistance then decreased. about 0.8125 ohms / cm; this value remained constant thereafter.

! times the operations of Example 2 were further Hand bows (see Table I) made; here was the Length of the carbonaceous fibers about 6,350 mm.

- Table I -

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Tab el Ie

Thickness Specific Resistance mm (Ohm / cm)

Example Solids (mil) Before After

Melting Melting

6 * carbonaceous 0.000178

Fibers (99.9 * carbon- (0.007) 0.322 0.287

material)

12 * grass microfibers (6,350 IMi length)

58 * Asbestos, paper quality

24 * meltable powdered phenolic resin

13 * carbonaceous 0.000178 0.098 0.084

Fiber (99.9 * carbon (0.007) carbon)

12 * glass microfiber (6.350mm length)

fusible powdered phenolic resin

Asbestos, paper quality -

3.4 * carbonaceous 0.000165 0.975 0.813

Fibers (99.9 * carbon (0.0065) carbon)

12 * glass microfibers (6.350mm length)

24 * meltable powdered phenolic resin

60.6 * asbestos, paper quality

1.25 * carbon 0.000152 3.60 2.94

term fibers (99.9 * (0.006) carbon)

12 * glass microfibers (6.350mm length)

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$ 24 meltable powdered Phenolic resin

62.75 * asbestos

(Paper quality)

11 * carbonaceous 0.000143 2.79

Fibers (90 * carbon (0.0045) carbon)

88 * Synthetic mica

1 * alum and polyethyleneimine coagulant

20 * carbonaceous 0.0027 0.313

Fibers (90 * carbon (0.011) carbon

10 * glass microfibers

69 * Synthetic mica

1 * alum - and - ~ ^ «." ...- lenimine coaguli determined

9 * carbon containing 0.000178 1.806 fibers (90 * carbon (0.007) carbon)

16 * glass microfibers

75 * asbestos (paper quality)

8 * carbonaceous 0.000216 1.641

Fibers (90 * carbon (0.0085) carbon

92 * asbestos (paper quality)

16 * carbonaceous 0.0027 13.2

Fibers (90 * carbon (0.011) carbon)

24 * mica flakes

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$ 59 glass microfibers

Alum coagulants

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carbon fiber (90 * carbon)

Pulp from wood pulp

Asbestos (paper quality) 0.000127 (0.005)

0.798

35 * carbonaceous

Fibers (12.7mm length 90 * carbon)

65 * Wood pulp pulp 0.00029 0.132 (0.0115)

% carbon fiber (90s * carbon)

Zinc oxide

65 * pulp v, wood pulp

Alum coagulants

0.00020 (0.008)

2.21

15 9 * carbonaceous 0.00035

Fibers (90 * carbon- (0.012 (

material)

Titanium diocide

pierb hliff

alum

Paper pulp from Holzsc

2.02

16 I45i- carbonaceous 0.00025

Fibers (19.05mm length, (0.010) 9i ¥ carbon)

Paper pulp - ^ wood pulp

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17 2196 carbonaceous 0.00025 0.195 -

Fibers (25.4mm length, (0.010)

90 * carbon)

79 * paper pulp ν. Wood sanding

18 9 * carbonaceous 0.000165 0.540 -

Fibers (99.9 * carbon) (0.006)

90.9 * pulp from wood grinding
0.1 * wetting agent

Example 19

A roll of conductive paper, 8 inches wide, the carbon-containing fibers and wood paper pulp (50 degrees Schopper-Biegler grind) was coated with a lithium sulfate coating 00.0381 mm thick), which was prepared according to the USA patent. The coated paper was in air dried and cut to a size that would fit the Western Union Desk fax facsimile receiver. An exam sample was given to the recipient and successfully drafted an image on the coated paper using standard procedures.

Example 20

A warming bucket for food and meals was made using paper containing carbon fiber proportions of the invention, constructed as a heating element. The back of a metal plate (25.4 cm; 50.80 cm) was made with covered with a thin electrically insulating coating that was resistant to that reached by the heating element

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elevated temperatures ₀ For work at 120 volts with a 300 watt heating requirement, the resistance of the heating element is 48 ohms.With metal electrodes making contact at both ends of the heating element along the 10 inch dimension, the resistivity of the heating element must be 24 Ohms per cross-sectional area (per square). A conductive paper comprising carbonaceous fibers and wood pulp according to these requirements was cut to size (size) of both electrodes and adjusted and then bonded to the insulating coating of the metal plate. Then a heat insulating film was used to cover the heating element; as a result, a heating unit was provided as a whole. When 120 volts were applied across the heating element, heat was generated evenly by this and transferred to the metal plate, with low-loss, very evenly distributed heat (heat) being provided over the surface of the bucket or trough. The advantages of this warming device included direct heat transfer due to intimate contact, large area heat transfer, lower element temperatures and the absence of hot spots due to local overheating.

- patent claims -

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Claims (1)

M 1726 - ¹⁶ - 1540849 Claims 1. Virtually infusible, porous, nonwoven, electrically conductive sheet having 1-35 wt. # Of substantially uniform having distributed, electrically conductive carbonaceous fibers, characterized in that the carbonaceous fibers an average fiber length of about 1.587 - 11.112 mm and an average denier of 0.25 - 5 and less k have at least $ 50 of insulating, infusible fibers, with the electrically conductive path has a specific resistance of about 0.036 - 60 ohm / cm «, 2. Porous, electrically conductive paper, characterized in that it is 1 - 35 wt «- # of substantially uniform distributed, electrically conductive, high carbon fibers having an average fiber length of about 1,587 11,112 mm and an average denier of 0.25 - 5 and at least $ 50 of infusible cellulose fibers, wherein the electrically conductive paper has a resistivity of about 0.036-60 ohms / cm. 3. Porous electrically conductive paper, characterized in that it contains at least 50 wt .- # of cellulose fiber material and 1-35 wt. -4> of substantially evenly distributed, electrically conductive, high-carbon fibers with an average fiber length of about 1.587-11.112 mm and an average denier of 0.25-5, wherein 909884/0785 M 1726 - 17 - the electrically conductive paper has a specific resistance value from about 0.036 - 60 ohms / cm. 4 «Practically infusible, porous, non-woven, electrically conductive web, characterized in that it contains at least 50% by weight of insulating infusible fibers and 1 to 35% by weight of essentially uniformly distributed, electrically conductive carbon-containing fibers with a carbon content mm and a 11,112 through-average denier of 0.25 - - having 5, wherein the conductive track .elektrisch Fät a resistivity of about 0.036 - of at least 80 wt .- S and having an average fiber length of about 1.587? 60 ohms / cm has. 5 · Electrically conductive track according to claim 4, characterized characterized in that the carbonaceous fibers have a carbon content between about 90 and 99.9 wt .- #. 6 «Electrically conductive track according to claim 4, characterized characterized in that the carbonaceous fibers have a carbon content above about 95% by weight. ■ 7 · Sine aqueous slurry, characterized in that that they are at least 50% by weight, based on total solids, of a cellulosic fiber material suitable for use on a paper machine, and from 3 to 35 on electrically conductive, high-carbon fibers 909884/0785 ~ ¹⁸ "1540S49 an average fiber length of about 1.587-11.112 mm and a denier of 0.5-5. 8. Electrical heating element, characterized in that it has electrical contacts which are bridged with a substantially infusible, porous, non-woven, electrically conductive paper, which contains at least 50 wt · - ^ of cellulose fiber material and 3-35 wt. 1 » of essentially uniformly distributed, electrically conductive, high-carbon fibers with an average fiber length of about 1.557-11.112 mm and an average denier of 0.5-5, the electrically conductive paper having a specific resistance of 0.036 to about 60 ohms per square unit Has. 9. Recording or recording sheet or disc that is suitable for use in facsimile reproduction, characterized in that it has an electro-sensitive coating a conductive substrate, the conductive substrate \ A substantially infusible porous niehtgewebte, electrically conductive path is at least 50 wt .-? S of insulating infusible fibers and 1-35 parts by weight of 5i substantially uniformly distributed and, optionally, electrically conductive carbonaceous fibers having an average Fiber length of about 1.587-11.112 mm and an average denier of 0.25-5, with the electrically conductive web having a resistivity of about 0.036-60 ohms / cm. 90988Λ / 0785 Le e rs e 11 e