US2748029A - Tub sizing of paper - Google Patents

Description

United States Patent TUB sIzINooF PAPER Donald R..Spear and William F. FoWler,zJr., Rochester,

N..Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Appli'cationA-pril-ZZ 1353, Serial No; 351,472

9 Claims- ((11.117-155) This invention relates to anewprocess of tub sizing paper; More particularly this invention relates totub sizing'photographic paper.

There are two commonly used methods of paper'sizing. According to one procedure, called beater or" engine sizing; the-paper chemicals, including those whichgive high dry-bursting strength, and high wet strength-are added to the=pulp slurry at some point prior to sheet. formation upon the wire of the paper machine proper. In the other means'of application,- the dried paper is run through a bath or tub containing the sizing material in aqueous solution, dispersion, or suspension, whereupon the paper'absorbs a quantity of the material. Such a process is called tub" sizing. Gelatin and starch are often used for this purpose. The-use of these materials improves various characteristics of highquality raw stock suchas adhesion ofother layers later applied, freedom from fibers, plus the usually-measured physical properties of the. sheet such as mullen and Wet' strength.

Such materials as gelatin are, however, hydrophilic, beingd'eposited in the interstices of and upon the surface-ofthe'rawstock from a water solution. They do not; therefore, result in any substantial improvement in tlieresistance to moisture of the paper. We have found that, if certain high polymeric aqueous dispersions (here.- inafterreferred to as hydrosols) are used in place of gelatin for tub sizing paper, a marked improvement results.

An object of this invention is to provide a paper sizing which-reduces the paper absorbency toward water. Another object of this invention is to provide a paper having'asurface particularly adapted to be. coated with a baryta coating in-photographic paper. manufacturing. A further object of this invention is to provide a sizing whichacts'as a binder on paper which can be applied hysurfacetreatment. An additional'object is. to provide a proeess for coating'paperwith a sizingto form a hard, ablrasive resistant surface.

'Ih'ehydrosols-which'we'use in our. process are disclosed in patent application Serial No. 272,709 by William F. Fowler, Jr., filed February 20, 1952.

These hydrosolsare' formed-by polymerizing together an unsaturated aliphatic amide and an acrylate,.preferably with some unsaturated aromatic monomer therein. Whenput'in the form of an aqueoussolution and/or dispersion, this mixture can be polymerized by a simple method whereby there. results .an emulsioirof thepolymer in a form for immediate use, such as for mixing with a solution of: gelatin or anyother water-soluble colloid with which-it is to-be.used. Our process involves-the 1188:0152

1. An unsaturated aliphatic amide which will be referred=to herein as the hydrophilic monomer. This compound. will. be. one. having the following structural formula:

Patented May. 29., 1.95.6

where R1 is a hydrogen, halogen, alkyl or cyano v substituent and R2 and R3 may beeither hydrogen or alkyl. I

2. A monomer having the following structural formula:

R4 OH J(I3O -R;-

wherein R6 is hydrogen, halogenlor amalkyl, andRv, Ra, R9, R10 and R11 may each be any-of-thefollowing: hydrogen, halogen, alkyl, nitro, cyano or dialkyl amino.

In compounding the monomers, the monomers designated 1 and 2 should each bepresentiinia proportionat least 2% of the total monomer composition. However, the sum of these two monomers should constitute atleast 30% of the composition. The class of. monomersdesignated 3 should not constitute any more-than 70%. of the total monomer mixture employed. Although: inv some cases it may be desirable to entirely dispense with the unsaturated aromatic constituent, it is preferredthat at least 5% thereof, based on the total monomeripresent, be used so as to assure the obtaining ;,of apolymer which is free of tackiness under all conditions-of.operation. As an example of compounds which are useful as. constituent 1, any of the following unsaturated alpihatic amides are useful for this purpose:

1. Acrylamide 2. a-Ethyl acrylamide u-n-Propyl acrylamide a-Isopropyl acrylamide a-n-Butyl acrylamide u-n-OctyI acrylamide N-methyl acrylamide N-ethyl acrylamide N-isopropyl acrylamide 10. N-n-propyl acrylamide 11. N-n-butyl acrylamide 12. N-isobutyl acrylamide"- 13. N-n-hexyl acrylamide 14. N,N-dimethyl acrylamide 15. N,N-diethyl acrylamide 16. N,N-di(n-propyl)acrylamide 17. N,N-di(isopropyl)acrylamide 18. N,N-di(n-buty1)acrylamide 19. N,N-di(n-butyl)methacrylamide 20. Methacrylamide Acrylic acid esters: which; are useful as constituent i 2 in the? composition; refrredzto: above are the: following:

. Methyl acrylate' Ethyl acrylate n-P'ropyl acrylate Isopropyl acrylate'r- 'Isohutylaeryltrte Ioamyl tacryl'ate n=Hexyl acrylate" 9. 2-ethyl hexyl acrylate n-Octyl acrylate n-Decyl acrylate Methyl methacrylate Ethyl methacrylate n-Propyl methacrylate Isopropyl methacrylate n-Butyl methacrylate Isobutyl methacrylate n-Amyl methacrylate 2-ethyl hexyl methacrylate n-Octyl methacrylate n-Decyl methacrylate S-Cyanoethyl acrylate B-Cyanoethyl methacrylate fi-Chloroethyl acrylate fi-Chloroethyl methacrylate n-Butyl acrylate Of the monomers of the unsaturated aromatic type which may be employed as constituent 3 where that is used, any compounds selected from the following list may be employed:

1. o-Methyl styrene 2. m-Methyl styrene 3. p-Methyl styrene 4. 2,4-dimethyl styrene 5. 2,5-dimethyl styrene 6. 3,4-dimethyl styrene 7. 3,5-dimethyl styrene 8. 2,4,5-trimethyl styrene 9. 2,4,6-trimethyl styrene 2,4,5-triethyl styrene o-Ethyl styrene m-Ethyl styrene p-Ethyl styrene 3,5-diethyl styrene p-n-Butyl styrene m-Sec-butyl styrene m-tert-butyl styrene p-hexyl styrene p-n-Heptyl styrene p-Z-ethyl hexyl styrene o-Fluoro styrene m-Fluoro styrene p-Fluoro styrene o-Chloro styrene m-Chloro styrene p-Chloro styrene 2,3-dichloro styrene 2,4-dichloro styrene 2,5-dichloro styrene 2,6-dichloro styrene 3,4-dichloro styrene 3,5-dichlor styrene 2,3,4,5,6pentachloro styrene rn-Trifluoromethyl styrene o-Cyano styrene m-Cyano styrene m-Nitro styrene p-Nitro styrene p-Dimethylamino styrene Styrene The preparation of the polymer is carried out by combining the monomers in an aqueous system. The amide constituent is soluble in water and the softener or plasticizing monomer, and the unsaturated aromatic compound can be incorporated by dispersing those in water, such as by the use of a wetting agent. For this purpose an anionic surface active agent is preferred, such as sodium lauryl sulfate. Other dispersing agents, however, such as (1) cetyl dimethyl ethyl ammonium bromide, (2) sodium stearate, (3) sulfonates of an octyl phenoxy polyethylene glycol, (4) sodium salts of alkyl-aryl sulfonates, (5) sodium salts of alkyl naphthyl sulfonates and (6) sodium salts of sulfated monoglycerides may be employed in this connection. The monomers ordinarily are present in a dilute solution, such as within the range of 560%, the monomer concentration used being not critical but governed by the convenience of the individual operator. Also incorporated in the dispersion is a catalyst adapted to promote the polymerization of the monomers. Either of two methods of polymerization may be used: (1) heating on a steam bath or (2) carrying out at substantially room temperature (IS-30 Q). Where a steam bath polymerization is employed, a water soluble per-compound may be employed as the catalyst, as, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, sodium perborate, sodium peracetic acid or the like. If, on the other hand, the polymerization 0f the monomer dispersion is carried out at room temperature, a redox system catalyst is employed, such as a mixture of sodium acid sulfite and ammonium persulfate or some other per-compound, a mixture of ascorbic acid and a per-compound or a mixture of a ferrous ion compound and a per-compound, or any other redox system catalyst which has been described as being suitable for promoting the polymerization of monomers. If the amide component of the dispersion is of the N- substituted type, it is advisable to carry out the polymerization by the second method, namely, using room temperature and a redox system catalyst. If, on the other hand, the amide employed is not N-substituted, either carrying out the polymerization at room temperature referred to as method 2 or at an elevated temperature, such as -120 C., as referred to as method 1, may be conveniently employed in preparing the hydrosol of the polymer in accordance with my invention. It is desirable in carrying out the polymerization that the mass be vigorously agitated, and that the liquid monomer be added over a comparatively short period. For instance, with vigorous agitation and fairly rapid addition of the monomer, products are obtained having a hydrosol particle size on the order of 0.1 micron or less in diameter. On the other hand, if the agitation is not as vigorous or the monomer is added over a longer period of time, a greater size results. The preparation of the polymer should be carried out using sufficient speed of agitation and of addition of monomer, that the size of the particles of the hydrosol prepared is not more than 1 micron. The time necessary for carrying out the polymerization in accordance with my invention is short, the completion thereof being determined by the absence of the odor of any monomer in the reaction mass. The resulting dispersion obtained may be used directly in mixing with aqueous gelatin compositions or in any other connection in which use thereof is indicated. When the amide employed is acrylamide rather than a substituted acrylamide, it is desirable to use the resulting product shortly after its preparation.

The examples presented herewith are intended to illustrate how our invention may be operated so as to improve the sizing of the sheet. It is, of course, possible to size either (a) waterleaf paper or (b) paper which has already been beater sized. Examples of both processes and results obtained are given below.

Example I .T ub sizing of waterleaf paper Percent n-Butyl acrylate 59.1 Styrene 25.2 Methacrylamide 15.7

The hydrosol was diluted to a solid content of 4.4 percent.

agmahae 5 Twelve pound waterleaf paper was cut into:8:in. X: 1.0v in. size, hand dipped into the dilute size, and;theexcess: removed by passing through two power drive press rolls; Thesheets were then dried at 220 F. for three minutes. on a rotary'drum dryer.

Physical tests were run on these sheets:

PHYSICAL PROPERTIES OF TUB-SIZED 12% LB. VVATERLEAF PAPER Example II.Tub sizing of already beater-sized paper The stock used for tub sizing the already beater-sized paper was white Insurance R stock, previously untubbed. This stock was treated with a hydrosol and gelatin mixture having 2.2% Gelatin and 2.2%. Hydrosol.

The'beater-sized stock was hand dipped into the dilute. size, and the excess removed by passing'through, two. power drive press rolls. The sheets were then dried at. 220 F. for three minutes on a rotary drum dryer;

The results of physical tests obtained upon the already beater-sized paper after tub sizing are given below.

PHYSICAL PROPERTIES OF PRODUCT F. TUB SIZING ALREADY BEATER-SIZEDBAPER 2.27 Gela- Gelatin 0 4.47 Property tin, 2.2% 0

4.4%) Hydrosol (Check) Hydrosol Weight, 1b./l,000 It. 20 21 22 Thickness: A Wet mils 5. 2 5.2 5. 2 Dry 111115 6. 8 6. 6f 6.3.7 Tear 68 76 68 C 68 72 72 Mullen, lb./in. 34 34 33 Wet Strength, lb. 14 15% Penetration, sec. 135 135 213 Expansion, percent- 3. 02 2. 81 2. 91 Tensile:

6P K 9/50 mm. width 7.8 7. 9 7. 8 C K9/50 mm.width 4.2 4.0 3. 9 Wet Tensile:

L K 9/50 mm. Width 2. 23 2. 15 2. 22 C K 9/50 mm. width 1. 34 1. 33 1.33 Porosity, sec 112 39 28 Cobb Size, 5 min. Distilled H grams 0. 227 0. 239 0. 169 Fold:

L 60 47 58 37 44 43 Permanence, percen 88 85 85 76 73 73 UV Reversion:

B "percent" 87. 9 87. 9 87. 1 R d 85.5 86.1 85.2 Difi d0 2. 4 1.8 1.9

Portions of the already beater-sized, subsequently tubsized samples, were directly sensitized with a photographic emulsion. These were tested sensitometrically and for general photographic quality, fresh and after various incubation periods at 120 F. and percent relative humidity up to 32 days. Results of these tests showed that, in general, no marked changes have been brought about in the photographic characteristics of the emulsion, through the use of this hydrosol either as partial or total replacement for gelatin in the tub-sizing process.

gelatinrby the hydrosol has (a) improved the sizing (as.

measured" either by Valley Penetration or Cobb size), (b) greatly increased the porosity, and (0) left the rest of the properties, essentially unaltered. (Porosity as. usedin this sense means porosity of the dry sheet to air.)"

It should be understood that our invention should be more broadly construed than to only include the particular hydrosol compositionmsed in the above examples. Any of the hydrosols described in application No. 272,709 might easily be substituted for this one; the degree of sizing depending to a considerable extent upon the relative amounts of hydrophilic and..hydrophobic monomers used.

The Cobb size test is described in T. A. P. P. 1. Method T441m45.

Valley penetration test is described in T. A. P. P. I. Instrumentation, Study XVI,v Correlation Between the Degree of Sizing as Determined by Valley, T. A. P. RI. and CurrierMethods.

We claim:

1. Aprocess for tub sizingphotographic paper wherein the paper is sized by a hydrosol prepared by polymerizing.

R3 are selected from the group consisting of hydrogen and.

alkyl, a monomer. having the structural formula:

R4 CH'z= JQ-O-Ru wherein R4 isza substituent selected from the group consisting ofhydrogen, halogen and alkyl, and R5 is a substituent selected from the group consisting of alkyl, cyano.

alkyl and halogenated alkyl, and a monomer. havingthe formula:

Re i l-C H:

R R o wherein R6 is a substituent selected from the group consisting of hydrogen, halogen and alkyl, and R7, R8, R9, R10 and R11 are substituents, each of which is selected from any of the following: hydrogen, halogen, alkyl, nitro, cyano and dialkyl amino, each of the first two monomers constituting at least 2% of the total monomer present, and their sum being at least 30% thereof, and the third monomer being no more than of the total monomer present and using the hydrosol as originally formed.

2. A process for tub sizing photographic paper wherein the paper is sized with a hydrosol prepared by polymerizing in an aqueous system a mixture of monomers having the following formula:

wherein R1 is a substituent selected from the group consisting of hydrogen, halogen, alkyl and cyano, and R3 .7 and R3 are selected from the group consisting of hydrogen and alkyl, a monomer having the structural formula:

wherein R4 is a substituent selected from the group consisting of hydrogen, halogen and alkyl, and R5 is a substituent selected from the group consisting of alkyl, cyano alkyl and halogenated alkyl, and a monomer having the formula:

wherein R6 is a substituent selected from the group consisting of hydrogen, halogen and alkyl, and R1, R8, R9, R10 and R11 are substituents, each of which is selected from any of the following: hydrogen, halogen, alkyl, nitro, cyano and dialkyl amino, the first and second monomers each constituting at least 2% and their sum constituting 3095% of the total monomer present, and the third monomer constituting 70% of the total monomer present and using the hydrosol as originally formed.

3. A process for sub sizing photographic paper wherein the paper is sized with a hydrosol prepared by polymerizing 40 parts of methacrylamide, 5.04 parts of sodium lauryl sulfate and 1.26 parts of potassium persulfate in 1000 parts of hot water while heating this solution, introducing thereto 150 parts of n-butyl acrylate and 64 parts of styrene, and continuing the heating of the mass until a white opaque hydrosol is obtained.

4. A process for sub sizing photographic paper wherein the paper is sized with a hydrosol prepared by polymerizing together a mixture of the following: 20 parts of N-isopropylacrylamide, 75 parts of n-butyl acrylate, 32 parts of styrene, 500 parts of cold water, .127 part of potassium persulfate, .127 part of sodium acid sulfite and 2.5 parts of sodium lauryl sulfate until no odor of monomer is present in the mass and a white opaque hydrosol results.

5. A process for tub sizing photographic paper wherein the paper is sized with a hydrosol prepared by polymerizing together with agitation 1000 parts of hot water, 1 part of potassium persulfate, 5 parts of sodium lauryl sulfate, 40 parts of methacrylamide, 77.5 parts of pchlorostyrene and 136 parts of n-butyl acrylate, and supplying heat to this mixture until a white opaque hydrosol results.

6. A paper containing as a sizing agent a hydrosol prepared by polymerizing together in an aqueous solution of an unsaturated aliphatic amide, the mixture of the amide, an aliphatic acrylate and a styrene monomer, the amide and the acrylate each constituting at least 2% of the monomer present, and their sum constituting at least 30% thereof, and the styrene monomer constituting not more than of the total monomer present therein and using the hydrosol as originally formed.

7. A process of sizing paper comprising tub sizing the paper with a hydrosol obtained by polymerizing n-butyl acrylate, styrene and methacrylamide in an aqueous system and using the hydrosol as originally formed.

8. A process for sizing photographic paper comprising tub sizing the paper with a hydrosol formed by polymerizing together in an aqueous solution of an unsaturated aliphatic amide, a mixture of the amide, an aliphatic acrylate and a styrene monomer, the amide and the acrylateeach constituting at least 2% of the monomer present, and their sum constituting at least 30% thereof and using the hydrosol as originally formed.

9. A process for tub sizing photographic paper wherein the paper is sized with a hydrosol prepared by polymerizing in an aqueous system methacrylamide, n-butyl acrylate and styrene, the methacrylamide and n-butyl acrylate constituting at least 2% and their sum at least 30% of the total monomer present and using the hydrosol as originally formed.

References Cited in the file of this patent UNITED STATES PATENTS 2,123,599 Fikentscher July 12, 1938 2,140,048 Fikentscher Dec. 13, 1938 2,343,095 Smith Feb. 29, 1944 2,550,652 Dreschel Apr. 24, 1951 2,592,218 Weisgerber Apr. 8, 1952 OTHER REFERENCES Serial No. 397,138, Fikentscher (A. P. C.), published May 9, 1943.

Claims (1)

1. A PROCESS FOR TUB SIZING PHOTOGRAPHIC PAPER WHEREIN THE PAPER IS SIZED BY HYDROSOL PREPARED BY POLYMERIZING TOGETHER IN AN AQUEOUS SYSTEM AND UNSATURATED ALIPHATIC AMIDE HAVING THE FOLLOWING STRUCTURAL FORMULA: