US1942706A - Process for protecting fiber products - Google Patents

Description

Patented Jan. 9, 1934 PATENT OFFICE PROCESS FOR PROTECTING FIBER PRODUCTS Fergus A. Irvine, New Orleans, La.

No Drawing. Application May 12, 1932 Serial No. 610,994

4 Claims.

The process is particularly directed to a treatment applicable to fiber products formed by felting, which process is generally similar to those utilized in the manufacture of paper, fiber boards, and the like, wherein the fiber is felted from a relatively dilute liquid suspension. Particularly the invention is directed to a process of incorporating into felted fibrous products substances to protect such products from the ravages of fungi, destructive insects, and the like, through providing a method of manufacture wherein a repellent, inhibiting, or toxic substance is distributed throughout the product toprovide the desired protection.

Due to the fact that certain of the inhibiting, repellent, or toxic substances which are or may be used in accordance with the teachings of this process are more or less soluble in water, at least in the somewhat acid liquid suspensions which are ordinarily used inthe manufacture of the products, it has been necessary to devise a method for the introduction of the substances into the 11m ished product whereby through the utilization of such method the losses of the substances are maintained as low as possible.

The invention is directed particularly to a process adapted for the addition of the desired substances to products formed according to the usual practices of paper making, as for example in the manufacture of products felted of fiber from dilute suspension of the fiber in water, with a water to fiber ratio of about 99:1 to 99.5 :0.5 or even higher, although in some such processes, particularly in the formation of thick fiber boards and the like, the ratio of water to fiber goes considerably lower, say to about that of 95:5.

In the general practice of paper making, in-

cluding the manufacture of boards, formed ar-' ticles and the like, the fiber suspended in the liquidwhich is usually water-in the proportion of about 1 part of fiber to 99 parts of water, is fed to a forming machine in which the product is felted in the desired form.

The forming machine ordinarily in its essentials comprises a head box to which a fiuid suspension having a fiber consistency say of 2 or 3% is fed, in which head box there is added the additional water necessary to dilute the consistency to that actually fed to the forming zone, and the head box is usually provided with means to maintain a constant pressure head so that when the diluted fiber suspension is fed to the foraminous member on which the fiber is felted it will at all times be fed under uniform conditions. As the fiber content of the suspension is felted out on the foraminous felting members, the liquid flows off through the foraminous member. The general features of construction and operation of machines of the type just described will of course be familiar to those associated with the production of paper, insulating boards, and the like, but for a concrete example of the general structure reference is made to Patent No. 1,187,476, issued to C. G. Muench.

The particular object of this invention is to provide a process wherein the inhibiting, repelling or toxic substance can be commercially incorporated into the fiber product in small amounts and distributed uniformly throughout the final product. The amounts of the substances ordinarily used for the purpose just mentioned are often less than 1% of the dry fiber weight of the product and this percentage in certain types of treatment may run as low as say 0.2% of the weight of the dry fiber.

The machines on which the products are formed, particularly those on which are formed the relatively thick insulating boards, are usually quite large, being about 12 feet wide, that is, they form a sheet 12 feet wide, and the capacities of these machines are in the neighborhood of 100 tons of finished board product per 24 hours of operation. If the suspension of fiber is in a ratio of 99:1, a machine producing 100 tons of fiber per day would have run through it suspension liquid to the amount of 9900 tons or more per day. In a case in which the inhibiting, repellent or toxic substance is used in an amount of 1%, this would mean that there would be one ton of such substance incorporated into 100 tons of fiber, and since this 100 tons of fiber is fed to the machine suspended in 9900 tons of water, it will readily be seen that in the tremendous amount of suspension liquid passing through the machine the inhibiting, repellent or toxic substance may very easily be lost by being dissolved if the conditions under which it is used are such thatthere is opportunity for the material to dissolve.

When one considers that there is used but one ton of the inhibiting, repelling, or toxic substance to 9900 tons of water, it is readily apparent that if such substance should be soluble only one part in 10,000 and if time were allowed for the material to be dissolved it would substantially all be lost in the water drained off when the fibers are felted.

Due to the fact that most all substances usedparticularly for fungi or insect proofing-apparently are at least somewhat soluble in water, or are at least somewhat soluble when subjected to slightly acid conditions, the problem of the treatment of fiber products has been quite complicated. For reasons well known to the paper maker, it is almost uniform practice that the fiber suspension is maintained in a somewhat acid condition. A further complication of the addition of the substances to the fiber products arises from the fact that for thorough and uniform distribution of the added substances it is necessary that the materials be quite finely subdivided, which of course makes them more susceptible to being dissolved in the suspension liquid.

For a specific disclosure of the process of this invention, there will be considered the addition of arsenious oxide used as an insect and fungi toxic proofing to be added to a fiber product felted in accordance with the general process of paper making.

The proportions of the substances used, which for the purposes of this invention need to be considered, are: water, approximately 10,000 parts; fiber, 100 parts; arsenious oxide, 1 part. Now arsenious oxide is soluble in water at ordinary temperatures, say at about F., in the proportions of approximately 0.3:100, but the actual ratio as used is 1:10,000, or 30 times that ratio at which the entire amount of arsenious oxide might be dissolved, so that it immediately becomes evident that the length of time during which the arsenious oxide remains in the suspension liquid must be held to an absolute minimum. A general matterwhich must also be given serious consideration is the fact that the one part of arsenious oxide must be distributed through the 10,000' parts of the suspension liquid. According to the facts just stated it is readily apparentthat the time of contact must be maintained at a minimum and that in fact the conditions of addition of the arsenious oxide must be such that it is accomplished substantially instantaneously.

According to this invention the various objects thereof are accomplished and the desired results are obtained through adding the finely divided dry arsenious acid at the head box of the forming machine. The dry finely divided powder may be sprinkled or dusted by any desired means onto the surface of the fluid suspension at the head box of the forming machine in such a way that the individual particles more or less fall on the surface of the liquid substantially separated, so that they more or less contact the surface of the liquid as individual and separated particles.

Application of the'dry material to the surface of the liquid as just mentioned is preferable and such condition should be approached as nearly as possible, but it is of course not absolutely essential that each and every particle of the dry powder shall individually and separately fall upon the liquid surface.

When the dry powder falls on the liquid sur-' face, the particles will of course be wetted, and just at that phase of the process it can be said that there is at that point a concentrated suspension of the treating substance. This condition of concentrated suspension of course will exist at this point only, since with the tremendous stream therein, preferably closely adjacent the forming machine, or the dry material may readily, through the provision of the proper equip:

ment, be fed into the machine vat, as by the utilization of impacting or concentric jets of the powdered material and liquid or gas discharging directly into the fiber suspension. If the process of fiber felting is one carried out with the heavier suspensions, that is, one wherein the suspension is about 3%, it should be borne in mind that the materials should be added at some point where there is relatively violent agitation since a uniform distribution through a 3% suspension is rather dimcult.

In describing this invention certain terms have necessarily been used only in a relative sense, since the exact exercise of the process is largely dependent upon the physical properties of the added substances, of the fiber material being felted, and on the various other conditions of felting; but the above example of utilization of the process is believed to clearly illustrate the funda mentals thereof.

Of course, substance other than arsenious oxide may be used according to the procedure which has been outlined; for example, various other inhibiting and relatively insoluble compounds containing arsenic, fluorides, borates, appropriate metallic salts and various appropriate organic compounds maybe embodied into the finished products.

It is thought that the process, its utilization and purposes have been sufliciently pointed out in the description heretofore given in detail and that one skilled in the art may in accordance with the teachings hereof readily utilize the invention of the process. As indicated, the exact conditions are almost entirely dependent upon the characteristics of the materials used and the conditions of use, and the terms used in the preceding" specification and in the claims to define the various steps and methods of utilization must be used with sufllcient flexibility to cover such variable conditions, for the terms have been so used.

Particularly in the use of the phrase relatively insoluble in this specification it is the intent that it shall in effect be used in the sense of meaning sufiiciently insoluble for the purposes hereof. The allowable solubility from the practical angle is that at which under the conditions of use, dilution, temperature, time, etc., the solubility is not sufilciently high that the process will be economicaliy'prohibitive.

Having pointed out the invention and described fully its process of utilization, I claim: a

1. The process of incorporating a toxic substance into a fibrous felted product produced according to the general procedure of paper making, that is, by felting fiber on a foraminous member from a dilute suspension of fiber in liquid,

to 1 part, and wherein the toxic substance is incorporated through its addition to the liquid suspension as a dry finely divided solid added in a manner whereby the dry solid particles are substantially separated one from another to contact and enter the suspension liquid individually.

2. The process of incorporating a toxic substance into a fibrous felted product produced according to the general procedure of paper making, that is, by felting fiber on a foraminous member from a dilute suspension of fiber in liquid, and in which the ratio of suspending liquid to suspended fiber is of an order of about 99 parts to '1 part, and wherein the toxic substance is incorporated through its addition to the liquid suspension as a finely divided solid added in a manner whereby the solid particles are substantially separated one from another to contact and enter the suspension liquid individually, the fiber then without substantial time lapse felted on the foraminous member and serving as a filter-bed to entrap and retain therein the solid toxic substance distributed throughout the fiber body.

3. The process of incorporating solid inhibiting, repellent or toxic substances into felted fibrous products, wherein the substance in finely divided form is incorporated into a water suspension of the fiber just prior to formation of the felted product.

4. The process of manufacture of a felted fiber product wherein the fiber material in fluid suspension and substantially in condition for felting has added thereto, in a finely divided solid state, an inhibiting substance; the inhibiting substance in dry form dusted on the surface of the fiber suspension, then thoroughly mixed and distributed therethrough and then promptly incorporated, integrally distributed as fine particles, in and throughout the product formed by felting the fiber from the suspension.

FERGUS A. IRVINE.