US1856946A

US1856946A - Fiber product and process of making same

Info

Publication number: US1856946A
Application number: US431057A
Authority: US
Inventors: William A Darrah
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-02-24
Filing date: 1930-02-24
Publication date: 1932-05-03
Anticipated expiration: 1949-05-03

Description

Patented ay 3, 193 2 on cmcaao, rumors mean raonuc'r am) PnocEss 0F No Drawing.

well as a desirable stillness.

The process I have invented utilizes in the main commercial equipment readily available on the open market and no drawing thereof is required.

\ 4 There are many methods for preparing fibers for use with my invention and I will describe one particular procedure which I have found well suited in the case of wood fiber prepared from wood waste. It should be understood that many modifications of this practice are still applicable without departing from the scope o my invention.

Assuming that the raw materials employed in this case is wood waste such as saw mill refuse, the pieces are passed through a shredder such as a hammer type and reduced to a mass of coarse fibers somewhat resembling straw. I have found it desirable to pass these fibers through two shredding operations using a considerable amount of fiber and a small amount of water, so that the fibers are rubbed upon each other during the shredding process. longer length fiber and reduces the amount of shorter or cut fibers.

After leaving the second shredder the fibers are preferably conveyed at a fairly high density to a Glafiin. FromtheClafiin the fibers are deliveredto a beater or equivalent device.

In the beater a portion of the product, which I will designate for purposes of convenience as soluble pitch, is added and the beating continued, preferably for one or two hours in order to thoroughly disseminate the soluble pitch throughout the entire fiber mass.

This action causes more of the Application filed February 24, 1980. Serial No. 431,057.

This operation is ordinarily-carried out with a low concentration of fibers and a large amount of water. For example, three to six per cent of fibers by weight, the balance being water, isa common condition which I find gives very satisfactory results. It should be understood of course that the nature of the fiber, the product beingproduced and many other factors control this ratio and I do not wish to be limited to any specific figure. a

After the beating has been completed and the soluble pitch-thoroughly disseminated throughout the mass, the mixture is preferably rendered slightly acid, as'for example,

by adding alum or other salts having an acid reaction,

This results in. the precipitation of the pitch from the material I have called soluble pitch. The pitch thus precipitated is attached to the fibers, rather firmly and uniformly in the form of small particles.

The mixture is then delivered to a sheet forming device of the type known as Fourdrinier, a rotary machine or an Oliver form 4 If it is desired to make a hard. board the next step in my process is to re-.

move instead of ninety-five percent of the water, somewhere in the neighborhood of sixty percent of the water and then place the partially dried sheet between steam heated platens. Pressure is then applied to'the platens rangin from 500 to 1000 pounds per square inch. The combined effect of pressure and temperature is to produce a hard dense sheet theexact thickness being determined by the amount and kind of raw ma terial used and the amount of pressure and temperatures to which it is subjected.

During the pressing operation, moisture is driven from the central portion of the board to the surface where it is converted .into vapor. As a result, there is a steady flow of moisture from the central portion of the board to the surface. This flow carries with it small particles of fiber, loose portions of Inns and other pitch or size and various materials. These fine materials form a relatively hard homogeneous mass which acts as a cement or filler for the surface of the board and gives it water resistant properties. Filling the interstices with this cementin material also increases the strength of the oard as well as materially improves its appearance. Such a board has a hard glassy surface which is strong, water-resisting, durable and usually a good insulator against electricity.

Referring to the substance which I have designated as soluble pitch, it should be noted that I may produce this material from various tars, pitches or resins. I have found that there are a very wide; range of materials suitable for this purchase. For example coal tar or coal tar pitch, water gas tar, by-product coke, oven tar, wood tar, from wood distillation and many of the pitches and tars which result as a by-product from industrial heat treatments, are available.

For example in certain cases petroleum pitch, obtained from the distillation of fuel oil, is suitable and I have also used asphalt and various so-called petroleum products such as mineral wax, etc.

The material selected should be placed in a liquid condition, preferably if its character permits by the application of a gentle heat or if this is not feasible by the addition of the solvent such as benzine, naphtha, gasoline, kerosene, alcohol, ether, etc. Obvlously the exact solvent must be selected with a knowledge of the material used and inasmuch as commercial solvents for various pitches and tars are well known, myinvention is not restricted to the-specific solvent which is used. If necessary I may add a I slight amount of solvent and heat as in some cases a combined action is helpful. I

Having reduced the pitch or tar to a liquid or pasty form I next add one of the fatty acids, as for example, stearic acid, oleic acid, etc. The class of fatty acids is well known and I do not wish to limit my invention to any particular acid or group.

After thoroughly incorporating the fatty acids with the pitch in pasty form a small percentage ofbasic material is added. A wide range of bases may be employed for this purpose. For example ammonia, caustic soda, causitc potash, soda ash, various amines and substituted bases such as triethanolamine etc., may beemployed.

I have found also that such alkaline materials as borax, etc.,may also be. employed.

The base chosen must be selected with a view to the properties desired. I have found very excellent results are obtained by the use of substituted amines such as triethanol- 'be coke oven tar oleic acid 15%, triethanolamine 5%.

It should be understood that the above ratio is typical and a considerable variation may be made from the percentages given without departing from the spirit'of this invention. In many cases it is possible to materially reduce the percentages of the fatty the percentage acid and of bases, increasing of tar or pitch.

After the addition of the triethanolamine or other bases to the mixture of pitch and fatty acid, the material is then thoroughly stirred or mixed, preferably with the application of gentle heat, as for example a temperature of 160 to 200.

In some cases where the tar or pitch shows a decidedly acid reaction, it may be desirable to thoroughly neutralize such acidity before the addition of the oleic acid and the basic material. This is not always absolutely essential, but of greatest importance in cases where appreciable amounts of free mineral acid may be present. If the acid reacmay be reduced or possibly even eliminated. V

The mixture of tar or pitch, fatty acid and base may be treated in a homogenizer, but in many cases such elaborate treatment is unnecessary.

The resultant mixture is now ready to be added to water .in which it will promptly form a rather permanent suspension on t orough mixing or stirring. The mixture should preferably be added to warm water at a temperature of around 100 or slightly higher.

Thorough stirring and mixing should follow the addition. The water should preferably be either neutral or slightly alkaline in reaction. Acid reaction in the water is to be carefully avoidedat this stage of the process.

The amount of water'added' depends upon the subsequent treatment. In general, I have found that a ratio equivalent to from one part in twenty to one part in ten by weight, I

gives good results. That is to say, approximately one pound of liquid tar or pitch with additions toabout one gallon of water.

- This mixture may then be added in a beater or equivalent agitating device to the fiber suspension which has been previously described. I prefer to shred the fibers underthe conditions outlined previously in this specifica tion, under a spray of intensely hot water and if possible maintain the suspension of fiber quite hot until it reaches the beater or equivalent device. For example the water sprayed onto the fibers during the shredding process may to advantage be in the neighborhood of 200 F. Subsequent steps in the process will perhaps cool the water and fibers to 150 or thereabouts. At this temperature the addition of the tar or pitch mixture shouldtake place. Although many variations of these temperatures are possible without departing from the spirit of this invention.

After theaddition of the tar or pitch mixture to the fibers the materials should be intimately commingled. This can be accomplished by operating the beater or equivalent device for a period of an hour or thereabouts.

After the pitch or tar has been thoroughly distributed through the solution a mate rial having an acid reaction should be added. I have found that aluminum sulphate, alum, calcium chloride, various salts which dissociate giving an acid reaction, or various dilute acids may be employed. I prefer a ma terial such as alum or aluminum sulphate, however- The addition of the acid material appears to destroy the emulsion of the pitch or tar causing it to adhere rather uniformly to the fiber particles. This is best accomplished by continuing the action of the beater or the stirring device during the addition of the acid material. This reaction takes place rather promptly and under ordinary conditions ten or fifteen minutes beating is sufiicient although the exact time depends of course on the materials used, the temperature, effectiveness of the beater and other'obvious factors.

Having now precipitated the pitch or tar. onto the various fibers the resultant material is formed in a sheet in any of the well known ways. For example, the material may be passed over a Fourdrinier, a sheet may be formed on a rotary filter or ordinary rotary vacuum machines may be employed. The sheet thus formed is then passed through a dryer where the moisture is materially reduced. In the manufacture of a thick board the sheet formed on the Fourdrinier or rotary would ordinarily be one and one-half to two inches in thickness. Such a sheet would conbe pressed between felt strips on a continuous press removing 10 to 20% of the water.

Such a sheet may then be passed through a roller dryer in which the amount of water would be reduced to perhaps 50%. All of these percentages are merely approximate as will be of course variable depending on the amount of water in the sheet and the desired characteristics of the finished product. Fifteen to twenty minutes gives excellent results.-

In order to provide ready escape for the steam contained in the board a screen or other foraminous structure may be placed between the board and one of the platens.

Under the influence of heat and pressure the pitch or tar which has been uniformly distributed throughout the mass of materials, softens and forms a cementing medium which securely binds the fibers together. The resulting product is very strong, water resisting and is a good insulator of electricity. Obviously the characteristics of the resulting prodnot will vary with the amount and nature of the tar or pitch. If a flexible product is desired I preferably select a rather plastic tar or pitch and limit the quantity to two or three percent of the fiber of the board. If a hard rigid product is desired I preferably select a pitch or tar having a high melting point and one which is hard and rigid at ordinary roomtemperatures. I also increase the quantities very materially sometimes using twenty percent or moreof pitch or tar. It will be understood that my invention is not confined to any specific percentages as different results may be obtained by varying the percentages and character of the raw material.

In this specification I have used the term pitch or tar in a general sense to indicate inert organic materials which are frequently waste products. The term condensation product may perhaps be used in a general sense to designate this'class of substance. For example the tar or pitch resulting from the distillation of wood, coal or other organic materials is unquestionably a condensation product. Similarly water gas tar, asphalt, etc., are condensation products. In the same way the product produced by subjecting linseed oil to heat or to oxidation is a condensation product. I have used all of these various classes of materials including the .condensation formed from phenols and formaldehyde. I have also used the condensation product formed by combining tung oil with rosin. Each of "these products give a different resultant product and require obvious variations in preparation. In the following claims I am using the term condensation product to indicate the class of materials described in this specification.

It should be understood that I do not claim asmy invention the addition of li uid tar or pitch to aboard already formed. am aware that it has been proposed to add tar or pitch in liquid form, but such an addition does not 19 penetrate the fibers thoroughly or uniformly. Such a procedure also requires extremely large quantities of pitch or tar and the distribution is such that there is a decided tendency for the product to become sticky when subjected to heat or service.

On the other hand, the process which I have invented requires much less binder, gives an entirely uniform distribution of the binder throughout the thesheet without permitting sufiicient quantities of the condensation product to collect at anyone point to cause the sheet to become soft or sticky.

' The results of the uniform distribution in which the condensation product is attached to each fiber is far superior to the former method and also permits the surface of the board is strong and durable without being subject to subsequent softening under the conditions of practical use.

40 It is frequently desirable to use a mixture of several condensation products, thus com-- bining certain characteristics of each.

By the term drying oils used in claims 7 and specificat ons, I intend to designate those products which are used'in the'arts to form a firm hard film as in paints and similar products.

These oils include linseed oil, tung oil,'mix- ,tures of tung oil, rosin, etc. The exact-type of oil used will determine the various characteristics of the resultant product.

The preparation of drying oils, their blending, heat treating and other operations .are well understood in the art and form no part of this specification. I I Having now fully described my invention, what I claim as new and wish to "secure by Letters Patent in the United States, is as oofollows:

I 1. A fiber sheet, consisting of a felte'd'mass of. fibers cemented into Jan aggregate by a precipitated emuls on of oil.

2. A fiber sheet consisting of i felted mass, of fibers attached'together' y a substantially said fibers in said water me uniformly distributed containing drying oil.

3. In a fiber sheet a binder consisting o uniformly distributed product containing dryin oil and-rosin attached to said fibers.

cipitating such emulsion on said fibers, and then forming a felt from said fibers drying "rarity water from said felt, and finally hardening said oil.

5, The process of making a fiber sheet which consists in first dispersing said fibers ina solution, second adding to said solution an emulsion containing drying oil, third precipitating such emulsion on said fibers, and then forming a felt from saidfibers (1 ing said felt, and finally hardening the 011 in said felt by heat. I

6, The process of making a fiber sheet which consists in first dispersing said fibers in a solution, second addin to said solution an emulsion containing drying oil, third precipitating such emulsion o'n said fibers, and

then forminga felt from said fibers and drying said felt and oxidizing said oil while at an elevated temperature.

7. The process of making a fiber sheet,

wh ch consists in first dispersing said fibers in a water solution, second brushing said fibers while in suspension, third addin an emulsion containing drying oil to said fi rs -while in solution, fourth precipitating said emulsion by adding'a material having an acid reaction, fifth felting said fibers, and finally drying, and oxidizing said oil at an elevated temperature.

8. The process of making a fiber sheet,

which consists in first dispersing said fibers ina water solution, a second brushing said fibers while in suspension, third addin an emulsion containin drying oil to said bers while in solution, fourth precipitating said emulsion by adding a material having an acid reaction, fifth felting said fibers and finally drying and pressing said felt and oxidizing said oil while at an elevated tempera.- ture.

9. The process of making a hard board which consists in separating wood fibers and suspending them in a water medium, second adding an emulsion containi drying oil to ium and-intimately mixin third precipitating said emulsion, fourth orming a felt from said fibers carryingsaid preci itated emulsion and finally pressing saidelt at an elevated temperature, thereby hardening said oil.

10. The process of making a fiber; sheet which consists in sus nding fibers in a water medium, second a; ding to. said suspended fibers an emulsion consisting of drying oil and gum dispersed by an alkaline material,

third neutralizing said solution thus precipitating the emulsion upon said fibers, fourth felting said fibers and pressing and drylng said felt, and finally drying said drying oil.-

water medium, adding an emulsion contain-- ing a condensation product of drying oil and a substituted amine, bringing said mixture of fibers and emulsion to an acidcondition and finally felting, drying and pressing the resultant product, and hardening said drying oil.

14. A fiber sheet having a mixture of condensation product of hardened drying oiland fatty acid distributed substantially uniformly throughout its mass.

15. The process of making a fiber sheet which consists in first suspending a mass of fibers in a water medium, second mixing drying oil and fatty acid with an alkaline mate-' rial, third adding said mixtureof said drying oil to said fibers and uniformly mingling the two. fom'th precipitating said drying oil and fatty acid upon said fiber and finally felting said fiber and submitting said felt to the action of heat and pressure, thereby removing water fromsaid felt and hardening said drying oil.

16. The processof making a fiber sheet which consists in first suspending a mass of fibers in a water medium, second mixing a combination including drying oil and fat acid with an alkaline material,third adding said mixture including drying oil to said fibers and uniformly mingling the two, fourth precipitating said mixture including drying oil and fatty acid upon said fiber and finally felting said fiber and submitting said felt'to the action of heat, therebypermanently fixing said drying oil.

17. A fiber sheet consisting of a felted mass of fibers containing a substantially uniformly distributed binder formed from a mixture of tung oil, linseed oil and rosin in a polymerized condition.

18. A sheet consisting of amass of cellulose fibers through which is distributed a binder containing drying oil and rosin in the polymerized conditio WILLIAM A. DARRAH.