US2173829A - Unified paper web - Google Patents

Description

Patented Sept. 26, 1939 UNIFIED PAPER WEB Richard Gurley Drew, St. Paul, Minn., assignorto Minnesota Mining 8; Manufacturing Company, St. Paul, Minn., a corporation of Delaware No Drawing.

Application March 24, 1938,

Serial No. 197,957

a Claims.

While my invention has a broad field of use-' fulness, I have found it of peculiar utility for producing an impregnating composition and for the resultant product when applied to porous sheets for limiting the application of the spray of liquid finishing material such, for example, as

lacquers or paints employed in lacquering or painting operations in automobile body paint shops and Itherefore find it convenient to describe the invention in connection with such practice and product, it being understood, however, that such limited fields of specific description are employed purely for purposes of illustration of an example of the utility of the invention in its several phases, besides such other novel fields of utility as may appear or be hereinafter pointed out.

In the work referred to specifically, my improved impregnating compositions may be used for treating fibrous sheets such as paper adapted to be used as the backing material of adhesive coated sheet material used for holding paper aprons against surfaces on which it is desired to apply the lacquer, paint, paint spray or lacquer spray, such for example as glass windows, upholstery, rubber mats of running boards, bright metal parts, and as covering and wrapping materials in general.

My invention therefore resides in the provision of sheeting material generally and covering and wrapping material specifically, useful in connection with the operations described, and the provision of compositions for treatment of porous sheeting materials such as paper, and to processes for producing the same.

Thecompositionsprovided by my invention may be applied to paper or other suitable backing, particularly bibulous material, to form sheeted material capable of being stacked or stored in piled sheets, or formed in laminations, as by rolling the sheets, such as in the form of rolls of tape. For certain preferred work, my compositions may be applied to paper to impart minimum point contact and inherent elasticity by applying the same to paper which is toweled, crimped,

creped or otherwise shaped to present a surface other than fiat and which has extensibility beyond that of the fiat paper web.

00 Amongthe objects of my invention are the provision oi. a composition which may be applied to a base, such as paper, cloth or other bibulous material, providing a residuum in this base material which will resist infiltration of paints, lacquers or the like when the base material is 5 used as part of a masking adhesive sheet in painting, spraying or like operations; the provision of a composition for treating paper, cloth or the like porous material resulting in a product to which an adhesive coating maybe applied and the sheets stored in piles, stacks or laminations without the use of slip sheeting for separating one layer of the composite from an adjacent layer.

My invention still further has as its object the provision of a composition applicable to porous materials, such as paper and like sheeting material, which imparts to the paper by the residuum left thereon, highly desirable properties, characterized by the filamentary material of the paper being bonded together and rendered resistant to tearing and splitting when used as a backing for an adhesive coating, more specifically, the provision of a composition which may be applied to sheeted material comprising bibulous, uncalendered paper, to reinforce the same whereby an adherent adhesive coating may be applied for adhesively attaching the sheet to a surface, permitting removal of the composite without tearing or splitting of the paper or leaving a residuum of the adhesive on the surface to which the composite has been applied.

For a clearer understanding of my invention for the production of a unified sheet, resistant to tearing or splitting, by the impregnation of porous sheeting, my invention is predicated upon the impregnation of a porous sheet, such as porous paper, with softened or plasticized impregnating agents, such as proteinous materials comprising glue, and further resides in the discovery of the relationship of the impregnating agent, the plasticizing material and vehicle to most effectively carry out the objectives aforesaid.

The backing materials or webs to be impregnated, as preferred by me, are paper bases 45 which are preferably absorbent, approaching blotting paper, calendered or uncalendered. Preferably, however, this paper base is of the unsized, uncalendered variety and may be pressed, molded or otherwise formed to have the appearance of towelled fabric, such as by crimping or creping the same.

Variation of the nature of the paper base such as length or quality of the fibersor special treat- 5 ments which increase the strength for the processes herein contemplated which-do not materially affect its porosity may enhance the product or facilitate speed in production.

It is an important feature of my invention that 5 The composition of the impregnating solution may be as follows:

Typo Glue Glycerine Water Type C above mentioned represents the preferred procedure contemplated by me in that the backing is passed through a bath of the solution and thereafter passed through squeeze rolls, leaving sufilcient of the saturating solution in the web ultimately to leave a residuum in which the paper constitutes about 55% by weight and the residuum of glue and glycerine about 45% by weight, with the glycerine approximately 1.75 times the quantity of glue after separation of the water by suitable drying means.

Specifically, type A will give a thoroughly impregnated web in which paper constitutes 54%, glue 17% glycerine 29%.

Excellent results are obtained in carrying out the procedure under type C by passing the web through the impregnating solution described, squeezing out the excess to the point where the web carries approximately twice the weight of the solution, then partially drying on racks at a temperature of from 65 to 100 F. This is followed by dipping the web in a tanning solution of formaldehyde (4% by volume) and thence placed on racks where the web is dried at temperatures from to F.

The balance of the impregnating residuum to the paper, I have discovered, may be in the range of from 52 to 60 parts by weight of paper to 48 to 40 parts by weight of impregnant, with the plasticizing agent in the form of glycerine, from approximately 1.7 to 2 times the quantity of glue.

In connection with types A and D above enumer ted, the impregnating solution will not achieve this relationship of the paper to the impregnant and the plasticizing agent to the glue by one trip through the impregnating bath.

In the case of type B, the desired range of plasticizer to glue is not achieved but has utility for purposes hereinafter to be described.

To achieve the desired ratio in types A and D, the paper is first floated on the surface of the solution for a distance of approximately four feet, then dipped into the solution of the same formula and then passed through squeeze rolls, where the amount of solution to be applied is carefully regulated to give from about 24 to 2'7 parts by weight of the solution to 15 parts by weight of the paper.

The wet paper is then passed onto racks and into an oven where it is dried at about to F. The porosity of the treated paper may be controlled as is more specifically described in my application S. N. 29,122 filed June 29, 1935.

Compensation is made for the higher ratio of glycerine to glue above indicated by then impregnating the web with a glue solution'constituting 1 part glue to 2.25 to 3 parts water.

The preferred ultimate ratio as hereinabove given may be obtained by uniformly saturating the web through the expedient of the second dipping trip. Preferably, however, the second solution is applied from one side of the sheet, to obtain a gradient concentration from one face of the sheet to the opposite face, in the nature of a back sizing. g

After submitting the web to the second solution, the web is partially dried on racks at temperatures of 65 to 100 F. permitting the glue partially to\ set up and become firm. The web is then dipped into a tanning solution, preferably a The ultimate products made by the employ-- ment of the saturating solutions will be as follows:

Ratio of Type Paper Glue as glycerine to glue Percent Percent Percent It will be understood that in types A and D, the ratio of glycerine to glue may be uniform from one face to the other or may represent the mean and be gradiently proportioned from one face to the other.

Type B above specified represents a high ratio of plasticizer to glue, specifically, glycerine to glue, found desirable where this material is employed for making adhesive-tapes of the character used for masking tapes for spraying automobile bodies and in which the lacquer is subjected to a baking operation of from 240 to 275 F.

Where the masking tape is to be subjected to lower temperatures, types A, C and D are preferred, in giving greater adhesive union between the adhesive layer and the backing.

Though I have described in the examples above given a tanning agent in the nature of formaldehyde applied in the form of a solution, this may be applied as a vapor. Also, other tanning agents, such as gallic and tannic acids, chromium trioxide, chrome alum or other chromium and aluminum salts, soluble in water, may be employed.

The tanning action may be confined to one side and has the advantage of placing less strain 1 on the paper than by complete submersion, particularly where the formaldehyde employed is in the form of a solution.

Neutralization of the formaldehyde, when desired, may be accomplished by subjecting the paper to a limewater treatment.

Desirable results may be obtained in the formaldehyding treatment by retarding the action of the formaldehyde by the addition thereto of equal molecular percentages of ammonia and this solution is used in amounts equivalent to 5% of the aldehyde to the dry weight of glue. The formaldehyde and the retarding agent may likewise be added to the impregnating solution just prior to the saturation or impregnating step heretofore described, in which event during the drying of the paper, the aldehyde-ammonia content breaks down, to liberate formaldehyde, setting up, insolubilizing or tanning the glue.

While I have described glycerine as the plasticizing agent, it will be understood that this acts as a viscosity augmenting and water retaining purposes.

- riety.

agent and, accordingly, other agents which fiexibilize the glue and modify the glue may be used, with a certain amount of success, and for this purpose there may be illustrated the following:

(1) Sulphonated castor oil;

(2) Honey (crude or refined);

The above enumerated agents may be used only in part to supplant the glycerine.

The webbing as above made may be used as a backing for adhesive tapes or for wrapping Normally non-drying, or tacky or pressure sensitive adhesives may be employed or .normally water-soluble or heat reactivatable adhesives may be employed.

The webbing may also be waterproofed: For the latter purposes, a waterproofing coating may be deposited upon the glue impregnated web by dipping the web in a solution of asphaltum, removing the excess on the surface by means of pressure rolls. Coating compositions, such as paramn, Bakelite, a resinous condensation product resulting from condensing and resinifying a phenolic compound and an aldehydic compound, may be used. Drying oils, such as linseed oil and varnishes, may be employed. Asphaltum, because of its flexible-qualities and low cost may also be employed. This latter coating may be oi the tacky variety or or the more heat resistant vacoating either of the adhesive variety or primarily of the waterproofing variety, may be used as a waterproofing wrapping paper capable of being stacked or piled, without the use of slip sheeting and is particularly tough, resilient, and

resistant to shock.

In preparing the impregnating compositions, I have described the employment of hide glue and, in the case of type D, bone glue. Many kinds and grades of glue may be used and still produce, to a degree, desirable results, among which may be named water soluble gums, such as tragacanth, and acacia. The proteinous adhesives are preferred.

In general, it. will be observed that I have provided porous web impregnating compositions, a method of impregnating such web and a resultant unifying sheet of highly desirable properties for making masking tapes or wrapping materials.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent, is-

1. A method for the provision 01' a unified paper highly resistant to splitting or lamination which comprises impregnating a porous web of paper of the character which is normally bibulous and approaching blotting paper in texture with a proteinous solution of water containing a plasticizing agent to the point where impregnation is regulated to contain 24 to 27 parts by weight 01 the solution to 15 parts by weight 01' the paper, the solution containing approximately 1 part glue, 1.75 to 4 parts plasticizing agent, 3.5 to 6 parts of water, drying said web to the point where it approximately retains from 48 to 40 parts by weight of impregnant to 52 to 60 parts by weight of paper, with the plasticizing agent from 1.7 to 3 times the quantity of the proteinous agent.

2. A method for the provision oi a lmified paper highly resistant to splitting or lamination which comprises impregnating porous paper of the character which is normally bibulous and approaches blotting paper with an impregnating solution to the point where the paper retains from 48 to 40 parts by weight of the impregnant residuum to 52 to 60 parts by weight of paper, the. impregnant comprising glue and glycerine in the average ratio of approximately 1.7 to 2 times the quantity of glycerine to the quantity of glue, distributed from one face of the web to the other the impregnant being applied diluted in water in which the water content is substantially not less than the combined glue glycerine content nor greater than approximately six times the glue content.

3. A method for the provision of a unified paper highly resistant to splitting or lamination which comprises impregnating porous paper of the character which is highly bibulous and approaches blotting paper with a glue-glycerine solution in the ratio of approximately 1 part glue, 1.75 parts glycerine, 3.5 parts water, to the point where approximately 27 parts of the solution are retained by approximately 15 parts by weight of paper, drying the web to the point where the ratio of paper to impregnant residuum comprises about 56% paper to about 44% residuum, with the glycerine about 1.75 times the glue.

4. A method in accordance with claim 1 in which a solution containing a tanning agent is applied to tan the glue.

5. A method in accordance with claim 2 in v terial oi the character which is normally highly bibulous and approaching blotting paper impregnated with a proteinous material and a plasticizing agent in the range of from 52 to 60 parts by weight of the web to 48 to 40 parts by weight oi! the impregnant, the plasticizing agent being present in proportions 01' about 1.7 to 3 times the quantity of the proteinous material the impregnation being characterized by the effect obtained in impregnating the proteinous material and plasticizing agent in the presence of a water content substantially not less than the combined proteinous material and plasticizing agent content nor greater than approximately six times the content or the proteinous material. 1

8. A unified paper web highly resistant to splitting or lamination which comprises a porous web of paper of the character which is normally bibulous and approaching blotting paper impregnated with glue and glycerine to the point constituting 52 to to parts by weight of paper to 48 to 40 parts by weight 01' the combined glue-glycerine, with the glycerine aproinmately 1.7 to 2 times the quantity or glue the impregnation being-characterized by the effect obtained in impregnating the glue and glycerine in the presence 01' a water content substantially not less than the combined glue-glycerine content, nor greater than six times the glue content.

RICHARD Guam-r murw.