The opinion of the court was delivered by: SMITH
This is a suit under the patent laws for the infringement of two patents; the one, No. 1,753,775, hereinafter referred to as '775, issued on an application filed by the plaintiff on May 24, 1929; the other, No. 2,041,285, hereinafter referred to as '285, issued on an application filed by the plaintiff on September 28, 1933. These patents, like those heretofore considered and discussed in the related suit, 57 F.Supp. 388, pertain to the manufacture of paper and cover improvements in the process of sizing the cellulose fibers of which papers are made, and, although cognate, must be separately considered and discussed.
The patents in suit cover further improvements on the art of sizing paper in the pulp, and particularly on the inventions defined in earlier patents to the plaintiff, Nos. 1,558,845 and 1,589,947. The patents and publications of the prior art discussed and considered in the related suit, including the patents there in suit, are relevant and material to the issue of validity here presented, but a repetitious discussion of them would seem to be superfluous. It is, therefore, suggested that a reading of the earlier opinion, hereinabove cited, will facilitate not only a comprehension of the art but also a proper appraisal of the present patents.
The invention of this patent is defined in claim 3 thereof, which is typical, as follows: 'A method of sizing paper which consists in treating the paper making fibre with sulphate of alumina, allowing the fibres to absorb the alum' (sulphate of alumina) 'until the pH of the solution is over 5, and then treating the surface of the astringent fibres with a solution of rosin size.' (Emphasis by the Court.) The other claims, which are quoted in the footnote,
define nothing more than specific variants of the same invention. The dissimilarity of the respective claims is not substantial, and is, therefore, not material to either the issue of validity or infringement.
It is here urged by the patentee, as it was in the prosecution of his application for the patent, that the invention, as thus defined, is a specific improvement on the invention covered by an earlier patent to him, No. 1,585,469. The invention of the latter patent is defined in claim 2 thereof as follows: 'A method of sizing paper pulp, which consists in treating the fibers (while in the beater) with sulphate of alumina and adding a stream of size emulsion to the fibers (as they are entering the Jordan engine.') (Parentheses by the Court.) It is obvious, upon a mere comparison of the quoted claims, that the inventions of the patents are identical in substance, except for the allegedly novel concept of maintaining the hydrogen ion concentration in the stock, the degree of acidity, within the defined limits. It is of persuasive significance that upon rejection of the claims in suit on the earlier patent, this concept was urged by the patentee as the only critical distinction.
When the claims in suit are construed in the light of the prior art, as they must be, it is evident that the essence of the invention lies only in this allegedly novel concept of maintaining the hydrogen ion concentration in the stock, the degree of acidity, during the sizing operation, within the prescribed optimum, to wit, between 5.0 pH and 6.8 pH, the lower coefficient denoting the degree of highest acidity, and the higher coefficient denoting the degree of lowest acidity
at which an effective size may be coagulated. The process of the said claims is otherwise old, the successive steps thereof, to wit, the introduction of the aluminum sulphate into the stock, thus effecting the acidification of the fibers and the surrounding solution, followed by the introduction of the rosin size emulsion, thus effecting the coagulation of the size, having been disclosed earlier not only by the patentee
but also by others.
This, it appears from the cited references, was common practice in many paper mills long prior to its disclosure by the patentee.
It follows that the ultimate issue presented for determination is whether or not the embodiment of this allegedly novel concept -- conceived by others whose disclosures preceded that of the patentee, as will presently appear -- in a process otherwise old, is such an advance over the prior art as will support the claim to patentable invention. It is our firm conviction, based upon the reasons hereinafter expressed, that it is not.
The art of sizing paper in the pulp, as practiced in the modern paper mill, was discovered and disclosed by Moritz Illig
in 1807. This art, although not immediately accepted generally, has been in common use without substantial modification since 1880, when the manufacture of paper from wood pulp was found to be commercially feasible.
The development of this art, consistent with the progress of the paper industry, has been marked by numerous improvements on the method of application
but by few modifications of the chemical process. It is significant that the improvements on the chemical process, including that of the patent in suit, have been minor, despite extensive study and numerous explanations of the sizing phenomenon
The methods of application, as distinguished from the chemical process, and the pertinent improvements thereon, were adequately considered and explained in the opinion filed in the related suit. The present discussion is limited, so far as it is reasonably possible, to the chemical process, the applied chemistry of the art, to which the patent in suit is particularly and primarily directed.
The chemical process is one in the practice of which the hydrated cellulose fibers, suspended in a water medium, are so treated as to overcome their absorptive quality and impart to the finished paper its water repellent property. The chemical ingredients, aluminum sulphate (the coagulant) and rosin emulsion (the size), are successively introduced into the stock
in the course of its preparation and as it flows to the paper machine.
The resulting chemical reaction, properly controlled, produces a colloidal gel
of aluminum resinate and rosin,
which is adsorbed
by the cellulose fibers. The water of suspension is removed in the final operation, felting and drying, and the rosin size is thus rendered permanent, imparting to the finished paper its water repellent property
The chemical reaction is progressive and complex but for our present purpose may be sufficiently explained as follows: The solution of aluminum sulphate, an acid solution having a pH value of approximately 3.5 to 4.0, coagulates the rosin emulsion,
an alkaline 'solution'
having a pH value of approximately 8.0 to 9.0, thus producing the colloidal gel of aluminum resinate and rosin, which, as heretofore explained, is adsorbed by the hydrated cellulose fibers.
This adsorption, the ultimate sizing reaction, heretofore described in footnote 13, is ascribed to the colloidal properties of the components, the hydrated cellulose fibers and the gel. The described chemical reaction is influenced by several factors, such as beating, temperature, etc., but it is necessary to consider here only the one to which the claims in suit are particularly directed, the hydrogen ion concentration in the stock, the degree of acidity. The rosin emulsion is efficiently coagulated, producing the colloidal gel essential to the ultimate sizing reaction, only if the optimum of acidity, to wit, within the range of 4.0 pH and 6.8 pH,
is maintained in the stock throughout the reaction
It should be noted, however, that the ultimate sizing reaction, the adsorption of the colloidal gel by the cellulose fibers, is not influenced, except in efficiency, by the sequence in which the chemical ingredients are introduced into the stock.
The same reaction occurs either upon the introduction of the aluminum sulphate into the stock, previously treated with rosin size emulsion, or upon the introduction of the rosin size emulsion into the stock, previously treated with aluminum sulphate. The latter practice, embraced in each of the claims in suit, was followed in the industry for many years prior to the present invention,
and was disclosed by the patentee in an earlier patent, No. '469. It is apparent from the cited references that local mill conditions are frequently determinative of the practice
Thus far we have considered and explained the chemical process in the light of after-acquired knowledge -- that is, knowledge acquired since 1807, the year of Illig's discovery, but prior to 1929, the year of DeCew's alleged discovery -- in an endeavor to facilitate a proper understanding of the purported invention and a due appreciation of the prior art references hereinafter summarized and discussed. We now turn to a consideration and discussion of the earlier disclosures, from which it clearly appears that the patentee's contribution to the art, if any, does not transcend the common knowledge and skill of the art, the test of patentable invention.
It was common knowledge long prior to the present invention that the coagulation of the size, as distinguished from a mere precipitation of rosin on the cellulose fibers, was essential to the ultimate sizing reaction, the adsorption of the colloidal gel of aluminum resinate and rosin by the hydrated cellulose fibers. It was likewise common knowledge that an excessive degree of acidity in the stock impaired or destroyed the colloidal gel, producing instead a flocculent precipitate, thus affecting the efficiency of the ultimate sizing reaction.
The known methods of controlling the acidity in the stock, as well as the known methods of measuring the degree of its intensity, were, however, crude and inadequate. These conclusions, adequately supported by numerous references, are not disputed
It may be reasonably inferred that even under the earliest practice the hydrogen ion concentration in the stock, the degree of acidity, was maintained within the range of 4.5 pH and 6.5 pH. There is now conclusive proof that the size could not have been coagulated and an efficient sizing reaction thus produced unless the hydrogen ion concentration was maintained within this range; if the acidity of the stock fell below 6.5 pH (tending toward alkalinity), the rosin size would not have been coagulated but would have remained in suspension in the emulsion,
and, if the acidity of the stock rose above 4.5 pH (tending toward excessive acidity), the colloidal gel, admittedly essential to the ultimate sizing reaction, would have been impaired or destroyed, producing a flocculent precipitate.
The discovery of a method of maintaining the hydrogen ion concentration within predetermined limits, and its subsequent adoption by the industry, undoubtedly contributed to the efficient application of the sizing process, but the process remained unchanged
It appears from the cited references that prior to the present invention extensive studies of the sizing process were made by those who preceded the patentee. These studies were directed to the problem of controlling the hydrogen ion concentration in the stock during the sizing reaction and led to the discovery of control methods which were readily adaptable to the sizing process. The results of these studies were widely published, and a fund of pertinent knowledge was available to the patentee when he entered the field in 1929. The apposite publications are worthy of special consideration.
Beltzer, The Sizing of Paper, published in 1924.
This article emphasizes the importance of maintaining the hydrogen ion concentration of the stock within predetermined limits and recommends a simple method of control which has been superseded by the scientific methods hereinafter considered. It is therein recommended:
Page 843. 'The hydrogen ion concentration of the stock as it reaches the wire (should) be so low that, even if no size were added, it could not affect the indicator usually employed, namely, litmus test paper.'
Page 843. 'In practice, sizing is largely controlled by means of litmus test paper. It has been observed that in order to have a properly-sized sheet, the water should be very slightly acid to litmus when it reaches the machine wire. If the litmus does not redden even slightly after a minute, that is, if the water is neutral, the paper is practically unsized; and if the water has an alkaline reaction the paper is as porous as blotting paper. On the other hand, if the test paper reddens too quickly, the stock is too acid and the sizing will be defective; but the results will not be as bad as in the case of a neutral or of an alkaline reaction.' (Emphasis by the Court.)
This disclosure, if it is to be accorded its full significance, must be appraised in the light of that which was common knowledge to the skilled technician, to wit, that in the interpretation of the color change, blue to red, the degree of acidity is reflected in the intensity of the color and the rapidity of the reaction. If the hydrogen ion concentration of the stock, as it reaches the wire, is so low that it will not affect the indicator, the acidity of the stock must be below 6.5 pH and nearer 7.0 pH, the point of neutrality; if the hydrogen ion concentration of the stock is so high that the indicator 'reddens too quickly,' the acidity of the stock must be above 4.5 pH and nearer 4.0 pH. The predetermined limits of acidity, although not defined by Beltzer in terms of pH values, coincide with the transition range of the indicator, that is, within the approximate limits of 4.5 pH and 6.5 pH.
The relevancy of this reference may be challenged on its failure to define the optimum of acidity with accuracy. However, it is our opinion that this failure does not detract from the significance of the disclosure, especially where, as here, its teachings are clear to the person skilled in the art.
Thiriet and Delcroix, Electric Theory of Rosin Sizing, published in 1924.
These writers, without asserting any claim to original discovery, concede that the efficiency of the ultimate sizing reaction is influenced by the hydrogen ion concentration in the stock, the degree of acidity,
and emphasize the importance of maintaining the hydrogen ion concentration in the stock within predetermined limits, approximately 4.5 pH to 5.5 pH.
The relevancy of the articles, aside from the theory of sizing therein advanced in support of its teaching, lies in the following disclosures
Page 54, et seq. 'But in connection with these particularly convincing results we wish to say a word as to the method of applying our theory to the control of sizing in paper mills. The actual control method must be very carefully chosen, as otherwise disappointment is almost bound to follow. The results which we have given above were obtained only at the expense of a very close and careful control of operations.
'Various methods can be used: preliminary neutralization of the raw water with acid, substitution of sulphuric acid for part of the aluminum sulphate, direct addition of sulphuric acid in the beaters, etc. Each case should be carefully studied and treated according to the particular conditions prevailing. But whatever procedure be adopted, the principle of the method remains the same -- namely, to adjust the hydrogen ion concentration of the pulp suspension as near as possible to the optimum value for sizing.
'We make use of two colored indicators, methyl red and sodium alizarin-sulphonate, which have opposite color changes, the one from yellow to red and the other from red to yellow.
When the back water from the paper machine gives practically the same color with both indicators, the pulp suspension has the proper pH. If the methyl red is redder than the sulphoalizarin, the stock is too acid, while if the methyl red is yellow the pulp is too alkaline. The test is so simple that it can easily be carried out by the machine tender. Its two chief advantages, besides its simplicity are
'(1) The pH range over which sizing is possible is much wider than that over which the two indicators give approximately the same color. Consequently, any appreciable variation in the pH is detected long before the danger point is reached, and conditions can be corrected in time to avoid defective sizing;' (Emphasis by the Court.)
These writers recommend, as does Beltzer, that the hydrogen ion concentration in the stock, the degree of acidity, be maintained within predetermined limits. These limits, although not defined in terms of pH values, are fixed with certainty by the transition range of the respective indicators. The average mill operator, possessing nothing more than the expected knowledge and skill, can follow the teachings of the disclosure without difficulty. The degree of acidity in the stock at the 'paper machine,' at which point the sizing reaction has progressed to completion, is indicative of the hydrogen ion concentration in the stock at the time of the sizing reaction;
it is obvious that the pH reading at this point has no other significance.
It is evident, if the teaching of this reference is properly interpreted and accorded its full significance, that the hydrogen ion concentration conducive to an efficient sizing reaction is within the approximate range of 4.5 pH and 5.5 pH. This conclusion is supported by a later disclosure.
Thiriet and Delcroix, The Technique of the Use of Rosin Size in Paper Ma ing, published in 1926.
Page 393. 'The authors propose the following theory for explaining the mechanism of sizing: Over a certain range of hydrogen ion concentration, pH, the cellulose and rosin have electric charges of opposite signs, so that the positive rosin and negative cellulose are mutually attracted, and sizing is possible; outside of this range, the electrolyte is too acid or too basic, the cellulose and rosin have charges of the same sign and repel each other, so that sizing is impossible.' (Emphasis by the Court.)
Page 394. 'We have shown on a previous occasion that the rosin particles are held by the cellulose fibers because of electric charges of opposite signs on the surfaces of the two substances when the hydrogen ion concentration of the stock, as expressed by the pH, lies between certain limiting values. This attraction prevents the rosin being carried away by the water that drains through the paper machine wire; and at the driers, the size is permanently fixed to the fibers by fusion.'
Page 394. 'However, if we admit that the elementary constituents of matter are the negative electron and the hydrogen ion, it is easy to understand that the pH of a liquid exerts considerable influence on the equilibrium of the constituents of the solid immersed in it, that is, on the surface contact charge. We have determined experimentally, and verified in the mill, that very good results were obtained when the pH of the stock was kept in the neighborhood of 5.0 to 4.5.' (Emphasis by the Court.)
The particular relevancy of the reference lies in the specific teaching that the size may be coagulated and an efficient sizing reaction thus produced only if the hydrogen ion concentration in the stock, the degree of acidity, is maintained within a predetermined range, preferably 'in the neighborhood of 5.0 and 4.5' pH. The theory upon which this teaching is predicated need not concern us.
It should be noted that the writers, although recommending that the degree of acidity in the stock be maintained within the range of 4.5 pH and 5.0 pH, do not assert that this optimum is critical. It is conceded that the size may be coagulated and an efficient sizing reaction thus produced within a wider range; the only warning is against any 'appreciable variation' which would affect the efficiency of the ultimate sizing reaction. This teaching is in agreement with later disclosures.
Shaw, Hydrogen Ion Concentration in the Paper Mill, published in 1925.
Shaw, an associate technologist in the Bureau of Standards, demonstrated and proved by a series of experiments that the efficiency of the ultimate sizing reaction was influenced by the hydrogen ion concentration in the stock, the degree of acidity, and that this efficiency increased with the hydrogen ion concentration until the maximum of the optimum, approximately 4.6 pH, was attained. The results of these experiments are extensively reviewed in the cited reference. It is therein disclosed that an effective size is coagulated if the degree of acidity in the stock is maintained within the range of 4.6 pH and 5.4 pH.
The writer expresses the opinion 'that considerable economy in the use of alum and better control of the paper-making processes would be effected if an optimum degree of acidity were determined and observed in the mill.' It is not mere coincidence that the patentee likewise claims for his invention 'economy in the use of alum.'
Taylor, The Application of Hydrogen Ion Control to the Manufacture of Pulp and Paper, published in 1926.
This is a comprehensive treatise
in which the writer, after emphasizing the importance of hydrogen ion control in the manufacture of paper, recommends a control method which is practiced in many paper mills. Its relevant disclosures follow:
Page 38, et seq. 'The point in the paper making process at which control of acidity is of the greatest importance is, however, in the precipitation of the sizing. The water which is used in paper manufacture is in most cases alkaline. The reaction of the pulp will of course affect this reaction but, if the pulp is neutral, the natural alkalinity of the water is increased by the addition of the sizing agent which is usually rosin, this being added in the form of an alkaline rosin soap. This additional alkalinity will of course depend on the percentage of free rosin in the sizing.
'It has long been known that the stock should be 'slightly acid' during a part of the beating and at the time of delivery to the paper machine. This acidity is usually obtained by the addition of alum, which also precipitates the sizing. 'Slightly acid' is a very indefinite term which varies enormously, depending on the method of testing and on the meaning of the term to various operators. If the stock is too nearly alkaline, the sizing will not be completely and efficiently precipitated. On the other hand, additional alum over that necessary for precipitation of the sizing, ...