US1716654A - Peocess of treating highly-porous paper-uke material - Google Patents

Description

Patented June 11, 1929 UNITED STATES KIRKE L. .MOSES, F SPRINGFIELD, MASSACHUSETTS.

PROCESS OF TREATING HIGHLY-POROUS PAPER-LIKE MATERIAL.

No Drawing. Application filed May 28, 1923, Serial No. 642,084. Renewed August 4, 1928.

formed of loosely-matted fibres, and the further operation of subjecting said web or sheet to the action of a liquid for the purpose of impregnating it therewith. The sheet or web which is described in said applicationis one which has such a high degree of porosity and in which the fibres are so loosely matted together that it has very little inherent strength,.in fact so little that when the paper is wet it is very apt to break or tear apart by its own weight, especially if it is being acted uponby rollers or other similar devices While it is in a wet condition.

One of the objects of my present invention is to provide an improved method by which a tender paper-like web of the character above described or of a similar char.- acter can be successfully handled while in a wet or saturated state and without danger of its breaking or tearing apart. The use of my invention thus enables me to take a tender paperlike web such as above referred to and carry it through a bath containing water by which the. web is thoroughlysat-- ui'ated without danger of its breaking or tearing apart during such treatment.

In my. above-mentioned patent a highlyporous loosely-matted web is described as being subjected to a bath of latex or rubber emulsion for the purpose of impregnating it therewith. Such rubber emulsion contains a certain percent of water and the action of the water on aweb of suflicient porosityv or absorbency to allow of its being impregnated with the rubber emulsion or latex reduces the strength of the web to such an extent thatit is very apt to break or tear apart as above described.

While the present invention is highly advanta eous in connection with the process descri ed in the above-mentioned patent wherein this tender web is impregnated with rubber emulsion, yet the invention is equally applicable. in connection with any treatment of a tender web which involves the wetting of the web because the application of my invention to such method prevents the wet web from tearing or falling apart during any treatment to which it may be subjected and which entails the use-0f water.

While the present invention contemplates any suitable'way of preventing this highlyporous tender paper-like web from tearing or falling apart when it has been wet during some treatment thereof, yet in general it may be stated that the desired end may be accomplished by incorporating in the paper some strength-giving element which gives the paper the necessary strength when it is wet to prevent it from tearing apart but which. at the same time does not diminish appreciably the necessary high porosityof the paper, or render the paper appreciably less pervious to Water. Such strength-giving element may be incorporated in the paper-like material either before it is formed into the web and while it is in the pulpy state or after it has been formed into the web or sheet. 7

In practising the invention some strengthgiving element, such for instance as rubber latex, is incorporated in the pulp either in the beater or at some other stage in the paper-making operation before the pulp is formed into the web. The strength-giving constituent which is thus used may however be of any desiredcharacter so long as it will accomplish the required purpose of giving strength to the tender Web when formed without diminishing appreciably its poros' ity or its capability of becoming saturated with water and the invention contemplates the use of any material by which these re sults are secured. It is important, however, that the strength-giving constituent should be of such a nature that its presence in the paper stock .will not detract appreciably from the porosity of the web when it is formed and if rubber latex is used as a strength-giving element it is desirable to; use it in relatively small proportions.

The strength-giving constituent may be also incorporated in the web after it isv formed from the pulp, but, of course, before the web is-subjected to the impregnating op eration. This incorporation of the strengthgiving element into the web may be accomplished in various ways as for instance by spraying onto the web a solution which contains latex or rubber or some other similar constituent that will impart the desired strength to the tender web without, however, detracting appreciably from its porosity.

This spray of the rubber latex onto the web may be accomplished by means of any usual spray devices and immediately after the web leaves the paper-making machine or at any stage prior to the impregnation of the web. .Where the strength-giving constituent is delivered to the Web by the spray process it is desirable that the amount of rubber latex or other strength-giving material which is sprayed onto the web should be relatively small and only sufficient to give the web the added'strength necessary to enable it to be handled. readily during the impregnating process, it being necessary and desirable that the porous character of the web should not be reduced or appreciably effected by the incorporation of the strength-giving element into the Web.

Still another way of incorporating the strength-giving element into the highlyporous web before the impregnating process is to subject the web after it is formed to a very weak hydrocarbon rubber solution by which a very slight amount of rubber will be incorporated into the web. This may be done by passing the web directly.

after it is formed or at any stage between its formation and the impregnating process through a bath of the hydrocarbonrubber solution. bath should be so constituted that only a small amount'ol rubber will be incorporated in the web, that is, just sufficient rubber to give to the web, enough added strength to prevent it from tearing apart by its own weight when it is wet.

It is important that in the operation of incorporating the strength-giving element into the Web the high porosity of the latter should not be reduced because the highlyporous character of the web is requisite to carry out the subsequent impregnating process.

Other ways of preventing this very tender web from tearing apart or breaking when it is being subjected to a bath containing water and means by which it becomes wet may be employed without departing from the invention and while I have referred to various ways of practising the invention yet this has been done merely for illustrative purposesand Without any intention of limiting the invention to any or all of said ways.

The present invention is specially intended to be used in connection with a process of making a paper-like product which involves first the production of the highly- It is desirable, however, that this porous tender web or sheet of loosely-matted fibres and the subsequent step of impregnating said web or sheet with a solution con taining water and rubber or any other filling material which it is desired to incorporate in the porous Web, and it contemplates such a treatment of the web .or paper prior to its impregnation with the waterecontaining solution as will give the web a sufficient support either externally ,or internally to prevent it frombrea'king or tearing apart when it has become wet and saturated with the water-containing solution. My inven tion, therefiore, contemplates means for counteracting the weakening eiiect on the web due to the saturation of the latter with the waterin the water-containing solution and While I have preferred aboveto various ways of accomplishing this end yet I do not wish to be limited to any 01 them as the invention contemplates any appropriate means for preventing such a highly-porous web from tearing apart when being subj ected to a water-containing solution for the purpose of impregnating it while at the same time maintaining the highly-porous character of the web which is essential for the impregnation thereof.

I claim:

1. The method of making a paper-like product which consists mproducing a paperlike web having sufiicient porosity to permit it to be freely saturated with a filling material containing rubber and water but :having so little strength it will hardly hold :together when wet, distributing throughout the web a strength giving element which does not detract enough from. the porosity of the web to prevent the free saturation thereof with the filling material, and impregnating said web with said filling material.

2. The method of producing a paper-like product which consists in forming a paperlike web of sufficient porosity to freely absorb rubber latex and also having incorporated therein .a strength-giving element,

which gives sufficient strength .to the web when the latter is wet to prevent it from tearing apart and then impregnating said web with rubber latex.

3. The method of producing a paper-like product which consists in forming a highlyporous paper-like Web of loosely-matted fibres, impregnating said web with a liquid filling material containing water and before the Web is subjected to the impregnation process, incorporating therein a constituent which gives to thewe'b sufiicient strength to prevent it from tearing apart when wet but which does not appreciably decrease the high porosity of the web or its capacity to become saturated with the filling material.

4. The method of producing a paper-like product which consists in forming a highlyporous paper-like Web of loosely-matted fibres, Which Web has so little strength that it Will hardly hold together when Wet, incorporating in the paper stock a strengthgiving element which adds suflicient strength to the Web so that it will hold together when Wet but which does not detract from the high porosity of the web and sub sequently impregnating said Web with a filling material containin rubber and water. 10 In testimony whereo I have signed my name to this specification.

KIRKE L. MOSES.