US1819435A - Paper-like product and method of making the same - Google Patents

Description

Patented Aug. 18, 1931 UNITED S A -Es PATENT OFFICE xrnxr: L. mosns, or 'BitooKLiNE, MASSACHUSETTS Perm- IKE PRODUCT AND METHOD or MAKING- THE SAME No Drawing.

This invention relates to the sort of products obtained when an absorbent paper base is saturated or impregnated with various liq-s as aqueous liquid containing rubber or aqu'eous dispersions of rubber) gelatine, glue and glycerine containing liquids; and drying-oil containing emulsions, and aims to facilitate the application of the before-mentioned water containing materials to the paper web.

Some of the characteristics of the products so obtained are an increased tensile strength, an increased. tear resistance, an increased folding number, an increased resistance to an abrasive action, etc. The degrees of increase of strength and the increase along any particular line depends on the character of the filling material which is used. For instance, if the filling material is one containing rubber the resultant product. will have a considerably increased folding resistance and also an increased resistance to abrasion. While papers impregnated with gelatineand'glycerine have many of the characteristics common to the papers impregnated with the rubber material yet they fail to have the tear resistance and tensile strength when wet which is a conspicuous feature of the rubber-impregnated papers. I

In order to readily obtain a high degree of impregnation it' is' an advantage to use a highly-porous loosely-matted paper, but heretofore this has not been practical because of the difiiculty of preventing such paper 40 from tearing apart when it becomes wet during the impregnation process. Heretofore it has been found necessary to use for this purpose a paper web which is more or less absorbent but which depends for its strength while wet during the impregnating operation either upon a closer matting of its own fibres than is desirable or upon its fibres being of generous length with consequent greater entanglement to enable it to pass through the impregnating solution without danger of be- .structure and shorter fibre than are con- A ppiication filed March 2, 1925. Serial m. 12,590.

ing torn apart. In the first case the closer matting of the fibres is naturally accompanied bya loss of porosity that makes impregnation operations with some of the beforementioned materials difficult or impossible. 5 A paper as commonly made for saturating purposes in either of the foregoing waysleaves much to be desired for porosity and/or speedy'handling when wet, so that-much economy in its subsequent processing has heretofore been sacrificed.

This invention contemplates making available for saturation and manipulation when in a wet state papers of more loosely-matted sidered practical at present.

This object may be obtained by mixing with the paper-making fibre in the beater, or before it is formed into a web, a material calculated to give wet strength 'by' lightly attaching the paper fibres together in the final porous web with a water insoluble or water resistant binder, and then forming by a paper-making process a loosely-matted highly-porous web which, when dry, has its fibres lightly attached by a constituent which imparts conspicuous strength when the web isre-wet during subsequent processing. It is not essential that the waterresistant constituent be uniformly distributed throughout the mass of the web so that all fibres are attached to their neighbors, as it issuflicient if the distribution of such constituent is more or less spotty. And by the term lightly attached as used in the specification and claims I intend to cover either an attachment which more or less uniformly affects all the fibres of the web or is dotted irregularly throughout the mass of the web.

Among the various strength-giving elements which may thus be used to lightly attach the fibres of the porous sheet together may be mentioned viscose, rosin size, animal size, casein etc.

The viscose for this purpose may vary in character depending on the source of cellulosic material from which it is-manufactured. It is not necessary that it should be of a character in which there is complete conversion of the cellulosic material to cellulose xan 1 fibres of the viscose mingle with the paper fibres and form a network of adhesive fibres throughout the paper fibres and serve to lightly bind them together with a water resistant medium, and without the addition of a precipitant. On the other hand, where rosin size or animal size or casein or some other strength-giving elements are used it is desirable to add a precipitant so as to precipitate some of the size on the paper fibres. When viscose,'which, as its name implies, is of a highly viscous and sometimes jell-like nature, is added to a large quantity of water and mixed therewith, it will not be uniformly dissolved by the water, but, instead, will break up into small j ell-like particles. Hence, when viscose is added to paper-making material, these jell-like particles become distributed spottily throughout the fibre mass before it is formed into paper. WVhen, therefore, the paper is made, these jell-like particles are distributed throughout the web, and when they become dry, by the drying of the paper, they form a water-resistant binder which lightly attaches the fibres together, this result 'bein accomplished without the use of a precipitant. Any other sizing having a jell-like nature and which, like viscose, does not dissolve in the water, but, instead, breaks up into small jell-like particles, has the same advantages as viscose and comes within the scope of the present invention.

My invention contemplates the use of any of these strength-giving elements in a relatively small quantity which whilesufiicient to cause the paper fibres to be lightly attached and thereby impart the desirable wet strength to the web, is not,.however, in sufiicientquan tity to effect appreciably the desirable high porosity'of the web.

A paper web made according to the above method is substantially as porous as one which is produced from the same stock without the addition of the strength-giving element but it is appreciably stronger than paper made in the same way and of the same fibre but without the addition of this strength-giving constituent. The extra strength which is inherent in paper made in accordance with this invention is particularly conspicuous while the paper, when in a wet condition, is being subjected to the i manipulation necessary to impregnate it with an aqueous liquid containing rubber or an aqueous dispersion of rubber or, in other words, with materials containing water, such for instance as rubber, gutta percha, or balata containing latex preserved with ammonia; or emulsions or dispersions or suspensions of rubber involving water; or

glycerine additions to glue or gelatine or containing liquids, also various hardening' and insolubilizing agents, such as formaldehyde, parafiorm and the like may be used in conjunction with the glue, gelatine or casein solutions.

My invention is 'to be distinguished from the ordinary process of sizing paper and from the ordinary conception of the results of sizing paper. The purpose in view in sizing paper, as it is ordinarily carried out in papermaking operations, is to introduce into the paper either a loading material to render the paper solid and less porous, or a makeweight, or for the purpose of giving the paper a better finish or sometimes when used in a large quantity to give the paper water resistant qualities. Another purpose of size,

particularly rosin size, is to help retention of substantial quantities of such loading and filling materials as clay, etc.

'In all of the ordinary sizing operations of paper, some of which have been abovereferred to, the ultimate intention or effect is to render the paper less porous by filling to a greater or less extent the interstices between the fibres, and to stiffen and/or solidify the sheet. A calendering operation is generally use in conjunction with size to assist it to this end. On the other hand, the contemplation of this invention is a novel use of size with results quite opposed to the heretofore practice and generally understood function of size, for it is the purpose of my invention to add the strength-giving element solely for the purpose of increasing the wet strength of paper of any fibre length and to do this without appreciably affecting the extremely novel high porosity of the paper advantageous to allow free entrance of such materials as rubber containing latex.

WVhile the percentage of strength-giving .element which is used will vary somewhat loosely-matted fibres, increasin operations and .without danger that the web will be broken or torn apart with a consequent process interruption.

Heretofore, as far as is known, papers intended for saturation operations have not contained anything in the nature of a size,

soft to the touch, is not stiff or tinny, has no crackle, and is felt-like in structure and noticeably tender. Although the web is formed by a paper-makingprocess it is not a paper of commerce for none of the ordinarily practised uses of paper can beeconomically made of it, and it should not even be confused with blotting paper, which latter is absorbent and more or less porous but does not contain water resistant or insoluble :size and, therefore, does not have sufficient wet strength for the purposes described. This loosely-matted highly-porous paper-like web is designed solely for use as a component or base of the product obtained after it has later been treated with various water containing solutions which after drying alter its original characteristics. F

The manipulation of the web when in a wet state, which is referred to in the above description and the claims. is the manipulation to which it is necessary to subject the web during the saturation or impregnation process. I

The word latex as used herein is intended 'to include the aqueous dispersions of rubber or the aqueous liquids containing rubber,

some of which are mentioned above, whether or not said liquids have compounding or vulcanizing ingredients mixed therewith.

I claim:

1. The process of making a paper-like product which consists in forming by a paper-making process an absorbent web of the wet strength of the'web to a point w ere it will hold together when manipulated in a wet state by incorporating in the material of which the web is constituted a water resistant wet-strength giving ingredient which acts to said web with rubber containing latex and evaporating water therefrom.

taining rubber and evaporating water there i from.

3. A paper product comprising a porous base of loosely-matted fibres which are lightly attached together with viscose, said base being impregnated with aqueous liquid containing rubber.

4. A paper product comprising a porous base of loosely-matted fibres, which are light ly attached together with suflicient viscose to hold the fibres together when the porous web ]is wet, said base being impregnated with rub- 5. A paper product comprising a base of loosely-matted fibres which are attached together with suflicient viscose to hold the fibres of the base together when the latter is wet, said base being impregnated with the solid constituents of latex.

6. A paper product comprising a porous base of loosely-matted fibres, which base of itself has a wet strength below thatrequired to prevent the base from tearing when it is manipulated while in a wet condition, said fibres being lightly attached to,-

gether by water-resistant material which imports into the base suflicient strength to prevent the web from tearing apart when manipulated in a wet state, said base being impregnated with a filling material which toughens the base.

7. A paper product comprising a porous base of loosely-matted fibres, which base of itself has a wet strength below that required to prevent the base from tearing when it is manipulated while in a wet condition, said fibres being lightly attached together by water-resistant material which imports into the base suflicient strength to prevent the web from tearing apart when manipulated in a Wet state, said base being impregnated with the solid constituents of latex.

8. A paper-like product comprising a base in the form of a web of fibres so loosely matted together that of themselves they are not capable of maintaining the integrity of the web when wet, said fibres being lightly at tached together by a sufiicient quantity of water-resistant material to prevent the web from tearing apart when manipulated in a wet state, the said base having these characteristics being impregnated with the solid constituents of latex.

In testimony whereof, I have signed my name to this specification.

KIRKE L. MOSES.