US2045052A - Paper manufacture - Google Patents

Description

Patented June 23, 1936 UNITED STATES of Massachusetts This invention relates to the production of sized paper filled with alkaline filler.

The principal object of this invention is to produce sized paper filled with alkaline filler in which the sizing is applied to the paper web.

A further object is to avoid the necessity for the heating of the paper web to a temperature sufficient to flux any thermoplastic material employed'as sizing agent.

A further object is the production ofv sized paper filled with alkaline filler by the application of non-thermoplastic sizing agent to the paper web.

A further object is the application of the sizing agent to the paper web in solution form, particularly in solution in an organic solvent.

Other objects and advantages of this invention will become apparent during the course of the following description.

In my copending application, Serial No. 487,377, filed October 8, 1930, of which the present ap plication is a continuation in part, I have described a method whereby paper filled with alkaline filler may be sized by the application of thermoplastic material, such as paraflln, in liquid association to a paper web containing alkaline filler. By "liquid associatio I mean that the thermoplastic material is present as such either in the form of an emulsion or solution. n the case of emulsions, or solutions in waterto the wet or to the already substantially dried eb; in the case of solutions made with solvents iscible with water, application is made only the already substantially dried web. After he evaporation of the liquid, a sized web reults. In order to secure uniformity of sizing, he web is raised to a temperature sufficiently igh to flux the thermoplastic material.

Further development of the above process has hown that sized paper filled with alkaline filler n which the sizing'is substantially uniform may e produced even when the paper web is not ubjected to a temperature sufficiently high to ux the thermoplastic material. This has been ound to be particularly so in certain cases where .re employed. The necessity of subjecting the ab to such fiuxing temperature appears to dend among other things somewhat upon the ature of the solvent employed but chiefly'upon he nature ofv the thermoplastic material used. ertain solvents appear to have the property of fleeting more uniform distribution of the ther- 1 oplastic material in the web, and likewise cer I iscible solvents, the application is made either olntions of thermoplastic material in a solvent PATENT OFFICE PAPER MANUFACTURE Harold Robert Rafton, Ando ver, Mass, assignor to Raffold Process Corporation, a corporation No Drawing. Application May 5, 1932, Serial No. 609,555

32 Claims. (Ci. 91-68) tain thermoplastic materials seem to distribute themselves more uniformly in the web than do others even whenthe same solvent is employed.

Although I do not-wish to be limited by any,

generalization, I have, noted that apparently cer- 5 tain materials of a waxy nature seem to have their sizing distribution in the web improved by fiuxing, whereas certain materials of a resinous nature seem to distribute themselves substantially uniformly in the web when in solution and do not appear to need fluxing.

The latter condition appears to be true where a resin such as'rosin is used in solution in ,a solvent, in which case only enough heat may be supplied to the web to evaporate the solvent without it being necessary to actually raise the temperature of the web to the fluxing or socalled sintering temperature of the rosin. Of course if such temperature should be reached, this is usually not objectionable; but as such temperature is not ordinarily reached in the evaporation of low boiling point organic solvents such as may conveniently be used in the practice of my process, and particularly where the solvent is evaporated under reduced pressure, it is not necessary simultaneously or subsequently to supply the necessary heat so thatthe web will reach such temperature. Any one of a number of solvents may be used, among which the chlorinated hydrocarbons such as carbon tetrachloride, ethylene dichloride, and the like, may be recommended as being particularly satisfactory. In the-preferred practice of my invention a web containing alkaline filler is formed, for example by feeding to the web-forming device of a paper machine a fibrous mix in which alkaline filler is present. In this web'a solution of thermoplastic material in a solvent, for example rosin in ethylene dichloride, is applied. The liquid content of the web is then evaporated and a 40 sized paper web filled with alkaline filler results. The point of application, the method of application, the concentration and amount of thermoplastic material to be applied, and other necessary or optional details of my process, are similar in general to those employed in my above referred to copending application, but for the sake of completeness will be fully set forth immediately below together with certain other features which I have found desirable.

The thermoplastic material may be applied in a solvent, which is usually organic, as the thermoplastic materials I employ are normally substantially insoluble in water. If the material be applied in a water-miscible organic solvent, such for example as ethyl alcohol, it may be applied at any convenient point on the paper machine either where the web is still in wet condition, for example at or just after the press rolls, or at a point where water has been substantially removed from the web, for example preferably just after the' driers; or the solution of the material may optionally be applied to the paper web subsequent to the paper machine by a separate process.

' In the case where a water-miscible solvent is employed and the solution is applied to the wet web, the wet web may then be dried as usual, and in the interest of economy suitable means should be provided for recovery of the solvent from the evaporated liquid. In the case of application of a solution containing such solvent to a dried web, provision must be made for subsequent removel of the solvent from the web, for example by passage of the web over driers or by festooning in a hot atmosphere, or the like. In any case, in the interest of economy, suitable solvent recovery means should be provided.

In the case of the use of a solution of thermoplastic material in a solvent substantially immiscible with water, and this is the type of solvent which I find it most convenient to employ, it is not suitable to apply such a solution to the wet web but it should be applied rather to the web after the web has been substantially deprived of its water, preferably subsequent to the paper maclers, and then provision must be made for removing the solvent such as by passage of the web over driers or through a hot atmosphere, with suitable provision for recovering the solvent. However, in some cases the application of the solution of the thermoplastic material may take place as an independent process subsequent to the paper machine operation, suitably by a coating or saturating machine in which means is provided for subsequent removal and recovery of the solvent.

The solution of the thermoplastic material may be applied to the web by any of the various methods for applying liquids to a paper web, such as by passing the web through a trough or vat containing the solution, or by applying the solution by a brush, .for example by a rotary brush, or by a contact roll or rolls, or by spraying or the like, or in the case of water miscible solvents by a supply box' at one or more of the press rolls. The method of application employed in any given instance is'that which is best adapted for use at the particular point at which the solution is applied and should be chosen with regard to the particular conditions to be met'in any given case, all of .which will be apparent to one skilled in the art. For example, I have found that the application by a trough followed by a pair of squeeze rolls is a convenient method of application, especially for use with solutions in water-immiscible solvents which are applied to the dry web.

The concentration of the solutions used depends to a certain extent upon the method of employing them andthe point of application. For application by a 'roll, the solutions may in general be more concentrated, but for immersion or spraying it is more suitable to have them relatively dilute. An example of a. suitable solution concentration to be applied by a contact roll is 10 per cent. of thermoplastic material by weight, whereas for applying by a trough a 5 per cent. concentration by weight is suitable. I do not, however, limit myself to these concentrations and they may be widely varied according to circumstances as indicated above and still produce satisfactory results,

.uents, the percentage of filler, and the like, but

of thermoplastic material to be applied.

' able means such as a pump should be employed for supplying the agent to the applying device, and

The amount of thermoplastic material required for sizing varies somewhat as will be apparent, with the grade of paper made, its fibrous constit- As the solution of the thermoplastic material is 1 preferably applied continuously to the web, suitthe amount of agent applied should preferably vary regularly with the paper machine speed and 2 be adjustable to the various grades and weights of paper run. Other things being equal, after proper adjustments are made, the amount of thermoplastic material applied may perhaps be most conveniently regulated by regulating the concentra- 2 tion of the solution employed.

In the case of a solution of thermoplastic material in a water-miscible solvent applied to a wet web, the evaporation of the solvent and the associated water is suitably accomplished by the application to the paper web of heat or reduced pressure or both such,'for example, as on the ordinary paper machine drier or in a vacuum drier, in either case with suitable means for the recovery 1 of the solvent. Where the solution is applied to the already substantially dried web, such as may be the case when a water-miscible solvent, and must be the case when a water-immiscible solvent, is employed, there is not present any substantial amount of moisture and thus the means for evaporation of the solvent from the web as well as the recovery means are somewhat simplified. Moreover, the amount of heat required for the evaporation of the solvent over that for the joint evaporation of solvent and water is considerably lessand thus smaller drying capacity is necessary. In this case, as in the case of the wet 'web application mentioned above, the evaporation of the solvent is suitably accomplished by the application to the paper web of heat or reduced pressure or both. An evacuated chamber such as a vacuum drier or the like may be employed, operated as part of the paper machine equipment or as a separate unit. Or my process may be carried out with less capital expenditure by means of solvent/evaporating apparatus operated in an enclosure which is maintained at substantially atmospheric pressure or just slightly below. A suitable apparatus for this purpose is described in my copending application Serial No. 640,714, filed Nov. 1, 1932. Such apparatus may be operated-as part of the paper machine equipment or as a separate step after the paper machine.

Whether atmospheric pressure or vacuum solvent evaporating apparatus be used suitable solvent recovery means should of course also be provided.

and is similar in appearance to and by ordinary observation cannot v be readily distinguished from ordinary sized paper hitherto made by other means, for example, from clay filled paper sized by the ordinary method 'of resin sizing in the definition thereof given above and is intended to exclude paper which is saturated or substantially saturated with the sizing agent in question. And where in the claims I speak of applying sizing agent in a solvent, as to a fibrous web, or distributing it therein, I mean that the quantity of such sizing agent so applied or distributed shall be insufficient to result in the production of paper saturated or substantially saturated with the sizing agent in question. It is to be understood that such sized paper as described herein is distinct from the so-called surfacesized or coated paper which is produced by applying animal or similar substantially water soluble size or a coating of similar nature to a paper web, either on the paper machine or subsequently by a separate process.

It is possible to employ my'sizing method for applying additional sizing to a web containing alkaline filler, which web is already partially sized by other methods, and such use of my process falls withinthe scope of by invention.

One advantage of my present improved process is that it simplifies my former process, and requires less heat for carrying it out. Another advantage is that it now opens up the possibility of using other sizing agents by this method which materials in themselves are not thermoplastic or, if thermoplastic do not flux readily at temperatures ordinarily employed in paper manufacture. Materials of the latter type are for example cellulose compounds or derivatives, for example esters such as cellulose acetate, nitrate or the like, and these as well as the non-thermoplastic materials may be dissolved in suitable solvents such as organic solvents, applied to the 1 paper web, and the solvent evaporated. Uniform sizing throughout the sheet is thus obtained despite the fact that the material itself is substantially non-fluxible or not readily fluxible at least at the temperature employed.

It is to be understood that I may if I desire actually apply heat to the sized substantially solvent-free web, providing that such heat is not sumcient substantially to flux the sizing agent employed.

In place of resins other thermoplastic mate- 7 rials may be used such as gums or the like, in-

eluding synthetic thermoplastics such as obtained for example by chemical condensation. In the case of non-thermoplastic sizing agents, I may use any such, including synthetic nonthermoplastic materials, such as for example as those obtained by chemical condensation. Nonthermoplastic materials are well known in the art, specific examples being the product formed on standing from beta-elaeostearin, such as referred to in Thorpe, Dictionary of Applied Chemistry, Vol. VII, Longmans,.Green 8: Co.,

New York,..192'7, page 227, last full sentence at bottom of second column; and infusible resins, such for example as the Baekeland infusible resin, referred to in Ellis, Synthetic Resins and Their Plastics", The Chemical Catalogue Co. 1110., N. Y., 1923, page 126, last paragraph. Also I may employ mixtures of thermoplastic and nonthermoplastic material if desired; and in certain cases mixtures of other material with either thermoplastic or non-thermoplastic material, said other material serving to modify the characteristics of said thermoplastic or non-thermoplastic material in known manner, such as in respect to plasticity, thermoplasticity, solubility, chemical composition and the like. Whereas I may use either thermoplastic or non-thermoplastic s izing agents substantially inert to alkali, this is not necessary as the agents I use may be reactive with alkali. In the iatter case where such agents in the broke from my sized paper filled with alkaline filler are reintroduced in the beater, they may tend to react with the alkaline filler to cause foam, which however, can be controlled by suitable means such, for example, as

by the addition of acidic material such as alum at the dilute stage of the papermaking process as has already been disclosed in one or more of my issued patents.

It is to be'understood, however, in respect to sizing agents which are saponifiable, such for extended to be confined to that condition in which it is substantially unreacted uponby alkali.

Where I speak of synthetic thermoplastic material such as obtained by chemical condensation (an example of which is the condensation of an aldehyde with a phenol), I mean to include material originally liquid or thermoplastic which may eventually become non-thermoplastic after application to the web.

Where I speak of sizing agents herein, such as for example either thermoplastic or nonthermoplastic material, I mean to confine said agents to material which is substantially insoluble in water. Inasmuch asv the sizing agents I employ are thus substantially water insoluble, naturally where I used the word solvent in connection with these materials, I mean to confine myself to solvents other than water which at temperatures sufliciently high to substantially injure the web, the resulting process would not be operative for the intended purpose. Therefore, I disclaim the use of solvents except those having sufficiently high vapor pressure, that is to say sufficiently low boiling point, that they may be substantially removed from the Web for example by at least one of the herein described procedures at a temperature which will not be sufliciently high to substantially injure the web.

By the term alkaline filler" I mean substantially water insoluble filler which when agitated in contact with freshly boiled distilled water, say for an hour, will impart a pH value to such water greater than 7.0, that is, which will be on the alkaline side of the neutral point. 'Among fillers in this group may be mentioned calcium carbonate, of which lime mud from the causticizing process is one form; calcium carbonate magnesium basic carbonate employed in the paper disclosed in my United States Patent No. 1,595,416,

issued August 10, 1926; calcium carbonate magnesium hydroxide disclosed in my United States Patent No. 1,415,391, issued May 9, 1922; and other substantially water insoluble normal or basic carbonates of alkaline earth metals, (which expression is herein intended to include magnesium) or compounds, double salts, or other physically associated mixtures of these with one or more other acid soluble materials of a substantially water insoluble nature. By the term alkaline filler I also intend to include fibrous material and/or other material such as paper coating constituents or the like containing one or more compounds of the character referred to, such as old papers or similar papers, broke", or the like.

When I use the word paper herein, I use it in the broad sense to include products of manufacture of all types and of all weights and thicknesses, which contain as an essential constituent a considerable amount of prepared fibre and which are capable of being produced on a Fourdrinier, cylinder, or other forming, felting, shaping or molding machine. 7

While I have described in detail the preferred embodiment of my invention, it is to be under-; stood that the details of procedure, the proportions of ingredients, and the arrangement of steps may be. widely varied without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, applying to said web substantially water insoluble sizing agent dissolved in a solvent therefor, said sizing agent in such solution being characterized by beingcapable of distributing itself in said web to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fluxing of said sizing agent occurs, said sizing agent in such solution being further characterized by being substantially unreacted upon by alkali, and evaporating substantially completely the liquid content of said web, but without bringing about any.substantial fluxing of said sizing agent in said web, said sizing agent applied to said web being sufficient in amount to impart sizing effect to said paper.

2. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, applying to said web substantially water insoluble sizing agent dissolved in a solvent therefor, said sizing agent in such solution being characterized by being capable of distributing itself in said web to impart a substantially uniform sizing effect thereto at a. temperature at which no substantial fluxing of said sizing agent occurs, said sizing agent in such solution being further characterized by being substantially unreacted upon by alkali, and evaporating substantially completely the liquid content of said web by means of reduced pressure and heat, said heat being insufficient to bring about any substantial fluxing of said sizing agent in said web, said sizing agent applied to said web being sufficient in amount to impart sizing effect to said paper.

3. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent dissolved in a solvent therefor, said sizing agent in such solution being characterized by being capable of distributing itself in saidweb to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fiuxing of said sizing agent occurs, said sizing agent in such solution being further characterized by being substantially unreacted upon by alkali, and evaporating substantially completely said solvent content of said web, but without bringing about any substantial fluxing of said sizing agent in said web, said sizing agent applied to said web being sufficient in amount to impart sizing effect to said paper.

4. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent in such solution being characterized by being capable of distributing itself in said web to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fiuxing of said sizing agent occurs, said sizing agent in such solution being further characterized by being substantially unreacted upon by alkali, and evaporating substantially completely said solvent content of said web by means of reduced pressure and heat, said heat being. insufficient to bring about any substantial fluxing of said sizing agent in said web, said sizing agent applied to said web being suificient in amount to impart sizing effect to said paper.

5. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent dissolved in organic solvent, said sizing agent in such solution being characterized by being capable of distributing itself in said web to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fiuxing of said sizing agent occurs, said sizing agent in such solution being further characterized by being substantially unreacted upon by alkali, and evaporating substantially completely said organic solventcontent of said web by means of heat, said heat being insuflicient to bring about any substantial fiuxing of said sizing agent in said web, said sizing agent applied to said web being sufllcient in amount to impart sizing effect to said paper.

6. The steps in a method of manufacturing sized paper filled with alkaline filler comprising distributing substantially water insoluble sizing agent in a fibrous web containing alkaline filler by means of a vehicle comprising organic solvent in which said sizing agent is soluble,,said sizing agent being characterized by being capable of distributing itself by 'means of said vehicle in said web to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fluxing of said sizing agent occurs, said sizing agent being further characterized by being in a condition in which it is substantially unreacted upon by alkali, and evaporating substantially completely said organic solvent content of said web, but without bringing about any substantial fluxing of said sizing agent in said web, said sizing agent distributed in said web being sufficient in amount to impart sizing effect to said paper.

'I. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, applying to said websubstantially water insoluble sizing agent comprising thermoplastic material dissolved in a solvent therefor, said sizing agent in such solution being characterized by being capable of distributing itself in said web to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fluxin'g of said sizing agent occurs, and evaporating substantially completely the liquid content of said web, but without bringing about any substantial fluxing of said thermoplastic material in said web, said sizing agent applied to said web being sufficient in amount to impart sizing effect to said paper.

8. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, applying to said web substantially water insoluble sizing agent comprising thermoplastic material dissolved in a solvent therefor, said sizing agent in such solufilled with alkaline filler comprising preparing a 'flbrous web containing alkaline filler, substantial- 1y drying said web, applying to said substantially dry web substantially water insoluble sizing agent comprising thermoplastic material dissolved in a solvent therefor, said sizing agent in such solution being characterized by being capable of distributing itself in said web to impart'a substantially uniform sizing effect thereto at a temperature at which no substantial fiuxingof said sizing agent occurs, and evaporating substantially completely said solvent content of said web, but without bringing about any substantial fiuxing of said thermoplastic material in said web, said sizing agent applied to said web being sufficient in amount to impart sizing 'eifect to said paper.

10. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web,'applying to said substantially dry web substantially water insoluble sizing agent comprising thermoplastic material dissolved in a solvent therefor, said sizing agent in such solution being characterized by being capable of distributing itself in said web to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fluxing of said sizing agent occurs, and evaporating substantially completely said solvent content of said web by means of reduced pressure and heat, said heat being insuflicient to bring about any substantial fluxing of a fibrous web containing alkaline filler, substansaid thermoplastic material in said web, said sizing agent applied to said web being sufllcient in amount to impart sizing eifect to said paper.

11. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent comprising thermoplastic material dissolved in organic solvent, said sizing agent in such solution being characterized by being capable of distributing itself in said web to impart a substantially uniform sizing eifect thereto at a temperature at which no substantial fluxing of said sizing agent. occurs, and evaporating substantially completely said organic solvent content of said web by means of heat, said heat being insuflieient to bring about any substantial fiuxing of said thermoplastic material in said web, said sizing agent applied to said web being sufficient in amount to impart sizing eifect to said paper.

12. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially ing itself in said web to impart a substantially uniform sizing effect thereto at a temperature at which no substantial fluxing of said sizing agent occurs, and evaporating substantially completely said organic solvent content of said web by means of reduced pressure and heat, said heat being insufficient to bring about any substantial fluxing of said thermoplastic material in said web, said sizing agent applied to said web being sumcient in amount to impart sizing eifect to said paper.

13. The method of'manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, applying to said web substantially water insoluble sizing agent comprising rosin dissolved in a solventtherefor, and evaporating substantially completely the liquid content of said web, 'but without bringing about any substantial fiuxing of said rosin in said web, said sizing agent applied to said web being sufiicient in amount to impart sizing eifect to said paper. 14. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, apply ng to said web substantially water insoluble sizing agent comprising rosin dissolved in a solvent therefor, and evaporating substantially completely the liquid content of said web by means of reduced pressure and heat, said heat being insuflicient to bring about any substantial fluxing of said rosin in said web, said sizing agent applied to said web being sufficient in amount to impart sizing effect to said paper.

15. The method of manufacturing sized paper filled with alkaline filler comprising preparing tially drying said web, applying to said substantially dry'web substantially water insoluble sizing agent comprising rosin dissolved in a solvent therefor, and evaporating substantially completely said solvent content of said web, but without bringing about any substantial fluxing of said rosin in said web, said sizing agent applied to said web being suiiicient in amount to impart sizing I effect to said paper.

16. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent comprising rosin dissolved in a solvent therefor, and evaporating substantially completely said solvent content of said web by means of reduced pressure and heat, said heat being insufficient to bring about any substantial fiuxing of said rosin in said web, said sizing agent applied to said web being sufiicient in amount to impart sizing effect to said paper.

17. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent comprising rosin dissolved in organic solvent, and evaporating substantially completely said organic solvent content of said web by means of heat, said heat being insuflicient to bring about any substantial fiuxing of said rosin in said web, said sizing agent applied to said web being suflicient in amount to impart sizing effect to said paper.

18. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent comprising rosin dissolved in organic solvent, and evaporating substantially completely said organic solvent content of said web by meansoi reduced pressure and heat, said heat being insufficient to bring about any substantial fiuxing of said rosin in said web, said sizing agent applied to said web being sufficient in amount to impart sizing effect to said paper.

19. The method of manufacturing sized paper filled with alkaline filler comprising preparing a fibrous web containing alkaline filler, applying to said web substantially water insoluble sizing agent comprising non-thermoplastic material dissolved in a solvent therefor, said sizing agent in such solution being characterized by being substantially unreacted upon by alkali, and evaporating substantially completely the liquid c'on-,

tent of said web, said sizing agent applied, to said web being sumcient in amount to impart sizing effect to said paper. v

20. The method of manufacturing sized paper filled with alkaline filler comprising preparing a. fibrous web containing alkaline filler, applyingto said web substantially water insoluble sizing agent comprising non-thermoplastic material dissolved in'a solvent therefor, said sizing agent in such solution being characterized by being substantially unreacted upon by alkali, and evaporating substantially completely the liquid content of said web by means of reduced pressure and heat, said sizing agent applied to said web being sufiicient in amount to impart sizing effect to said paper.

21. The method of manufacturing sized paper filled with alkaline filler comprising-preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent comprising non-thermoplastic material dissolved in a solvent therefor, said sizing agent in, suchv solution being characterized by being-substantially unreacted upon by alkali, and evaporating substantially completely said solvent content of said web by means of heat, said sizing cient in agent applied to said web being sufficient in amount to impart sizingeflfect to said paper.

22. The method of manufacturing sized paper filled with alkaline filler, comprising preparing a fibrous web containing alkaline filler, substantially drying said web, applying to said substantially dry web substantially water insoluble sizing agent comprising non-thermoplastic material dissolved in a solvent therefor, said sizing agent in such solution being characterized by being substantially unreacted upon by alkali, and evaporating substantially completely said solvent content of said web by means of reduced pressure and heat, said sizing agent applied to said web being sufficient in amount to impart sizing effect to said paper.

23. The method of manufacturing sized paper filled with alkaline filler comprising preparing a. fibrous web containing alkaline filler, substantially drying said web, applying to said substantially 20 dry web substantially water insoluble sizing agent comprising non-thermoplastic material dissolved in organic solvent, said sizing agent in such solution being characterized by being substantially unreacted upon by alkali, and evaporating sub- 25 stantially completely said organic solvent content of said web by means of heat, said sizing agent applied to said web being sumcient in amount to impart sizing efifect to said paper.

24. The steps in a method of manufacturing 30 sized paper filled with alkaline filler comprising distributing substantially water insoluble sizing agent comprising non-thermoplastic material in a fibrous web containing alkaline filler by means of a vehicle comprising organic solvent in which 35 said sizing agent is soluble, said sizing agent being characterized by being in a condition in which it is substantially unreacted upon by alkali, and evaporating substantially completely said organic solvent content of said web, said sizing agent distributed in said web being sufiicient in amount to impart sizing effect to said paper.

25. Sized filled paper comprising fibrous material, alkaline filler, and sizing comprising substantially water insoluble cellulose derivative deposited out of a solution thereof in a solvent.

26. Sized filled paper comprising fibrous material, alkaline filler, and cellulose ester deposited out of a solution thereof in a solvent.

27. Sized filled paper comprising fibrous material, alkaline filler, and sizing comprising substantially water insoluble non-thermoplastic ma.- terial substantially unreactive with alkali.

28. Sized filled paper comprising fibrous material, alkaline filler, and sizing comprising synthetic substantially water insoluble non-thermoplastic material -substantially unreactive with alkali.

' 29. Sized filled paper resulting from applying to a fibrous web containing alkaline filler substantially water insoluble sizing agent dissolved in a solvent therefor, said sizing agent in such solution being characterized by being capable of distributing itself in said web to impart a substantially uniform sizing eflect thereto at a temperature'at which no substantial fiuxing of said sizing agent occurs, said sizing agent in such solution being further characterized by being substantially unreacted upon by alkali, and subsequently substantially removing said solvent from 70 said web, but without bringing about any substantial fiuxing of said sizing agent in said web, said sizing agent applied to saidweb being su flamount to impart sizing effect to said paper. 76

30. Sized filled paper resulting from distributing substantially water insoluble sizing agent which comprises non-thermoplastic material in a condition in which it is substantially unreacted upon by alkali in a fibrous web containing alkaline filler by means of a vehicle comprising a solvent in which said sizing agent is soluble, and subsequently substantially removing said solvent from said web, said sizing agent distributed in said web being suflicient in amount to impart sizing effect to said paper.

31. Paper filled with alkaline filler comprising fibrous material, alkaline filler, and substantially water insoluble sizing agent, said sizing agent having been provided by deposition out of solution thereof in an organic solvent by substantially completely removing said solvent by evaporation,

' said sizing agent in such solution being char,-

acterized by being substantially unreacted upon by alkali, said sizing agent being further characterized by being capable of imparting a substantially uniform sizing effect at a temperature at which no substantial fiuxing of said sizing agent occurs.

32. Paper filled with alkaline filler comprising fibrous material, alkaline flller sizing, and, additionally, substantially water insoluble sizing agent, said sizing agent having been provided by deposition out of solution thereof in an organic solvent by substantially completely removing said solvent by evaporation, said sizing agent in such solution being characterized by being substantially unreacted upon by alkali, said sizing agent being further characterized by being capable of imparting a substantially uniform sizing effect at a temperature at which no substantial fluxing of said sizing agent occurs.

HAROLD ROBERT RAFI'ON.