US2072687A - Manufacture of plastic material - Google Patents

Description

Patented Mar. 2, 1937 UNITED STATES MANUFACTURE OF PLASTIC MATERIAL Thomas Robinson, Smitlitown, N. Y., assignor to Lancaster Processes, Inc., New York, N. Y., a corporation of New York No Drawing. Application January 29, 1938, Serial No. 61,319 a Claims.

This invention relates to fibrous compositions which, as prepared, are in plastic condition and become hard on setting, and is concerned more particularly with a novel composition of the type 5 described which contains fibrous material derived from the disintegration of paper stock, and a bituminous binder. The new material has physical characteristics such that it may be used to great advantage in the production of numerl0 ous articles, such as roofing elements in the form of shingles, tiles, etc., conduits, \battery boxes, and the like, by extruding, molding, pressing, and similar operations, and the new product can be produced rapidly and at low cost by a novel method which also forms part of the invention. The production of plastic fibrous compositions consisting of a disintegrated paper stock, and a binding agent has heretofore been proposed, and processes for the manufacture of such compositions-have been patented, but these prior, processes have not proved entirely satisfactory for various reasons. In some cases, the product has had physicalcharacteristics which limit its use, and which appear to be the result of incomplete disintegration of the paper stock to ultimate or individual fibres, or of non-uniform distribution of the fibres through the binding medium,

while in other cases, the process suggested is expensive both with respect to the actual manufacturing operations, and to the materials employed. g An example of a prior process for the production of plastic fibrous compositions of the type referred to is disclosedin Woodley Patent No. 1,156,122, and according to the process of that patent, a hard asphalt, such as gilsonite grahamite, or the like, is added to a suitable residuum oil, and the mixture is heated to reduce the i 40 asphalt, to liquid condition. The fibrous material, such as waste paper in moist or wet condition, is then added to the oil-asphalt mixture, and the material worked in a kneading or mixing machine. In these operations, the water does not combine to any material extent with the gummy binder. Upon completion of the kneading and mixing, the mass is heated to drive off the greater part of the water, and it is then sub- Jected to extrusion and finally shaped to proper form. The Woodley process as described in the patent thus involves the use of expensive hard asphalts, and in addition, the use of a kneading or mixing machine for the production of the plastic does not result in disintegration of the Blipaper stock to elementary fibre form, except possibly when carried on for a long period of time and with an excessive amount of moisture.

The presentinvention is, accordingly, directed to the provision of a novel plastic fibrous composition similar in some respects to that disclosed 5 in my copending application Serial No. 54,714 filed December 16, 1935 and produced from waste paper stock, the new composition being superior to those heretofore manufactured in that it has better physical characteristics and involves the 10 use of cheaper ingredients. According to the invention, I carry on the disintegration of the paper stock in an internal mixer which acts with a rolling, rubbing, and smearing action, and I introduce into the mixer water, a bituminous bind- 15 er, such as asphalt, and emulsifyingagents in such amounts that during the operation of the apparatus, the asphalt becomes fluid, and the water and asphalt combine to form an inverted emulsion, that is, one in which the water is the 20 dispersed phase, and the asphalt is the continuous phase. The emulsion so produced has great tenacity and subjects the paper to high hydraulic shear, so that, as the operation of the apparatus continues, the emulsion acts in cooperation with 25 the operating elements of the machine to pull the paper stock apart and separate the individual fibres or small fibre bundles from one another, the moist fibres being then substantially uniformly and homogeneously distributed through 30 the emulsion. The product thus formed is suitable for use without further treatment for numerous purposes, as for example, for the production of articles formed by pressing operations. For other articles, particularly those which are 35 formed by extrusion, it isrdesirable to add a further quantity of the asphaltic material, and this is preferably added to the charge in the-mixing apparatus before the batch is discharged.

The apparatus which I have found suitable for 40 the production of the new material is that known commercially as the Banbury mixer, and this mixer includes cylindrical chambers or troughs in which the working elements operate. These elements are mounted as arms on a pair of shafts, and each element has a leading edge which lies at such an angle to the walls of the chambers or troughs, that the materiakis forced against and rubbed and smearedalong the walls by the moving elements. Also, the material un-' der treatment is subjected in the mixer to impact and rolling actions, and as a result of the several operations performed on .the ingredients oi thecharge, heat is developed suflicient to soften the asphalt, the emulsion referred to is produced, andthe disintegration of the paper stock and the thorough distribution of the fibres through the binding medium take place.

As a specific example of the production of the new material, the following may be given. About 220 pounds of shredded waste paper is fed into. the mixing chambers together with a relatively small quantity of water, such as pounds. Small amounts of substances, such as lime, which promote the formation of and stabilize inverted asphalt emulsions, that is, emulsions in which the water is in the internal phase and asphalt is in the external phase, are then added, together with suitable amounts of soap forming materials, such as rosin, for example, about 15 pounds of resin and 5 pounds of lime being required for 220 pounds of paper. This mixture is treated for a few minutes in the Banbury mixer to effect a preliminary disintegration of the paper, and when the paper has been thoroughly softened and defibred to a substantial degree, asphalt is introduced into the mixing chambers. The asphalt that may be employed is a hard oxidized asphalt of about 220 F. melt point, and it is introduced either in solid or fluid condition and in an amount approximately equal to the weight of the paper.

The mixing operation is .then continued, pressure being maintained in the mixing chambers so that although the temperature therein may rise to about 220 F. so that the asphalt becomes soft and fluent, only a part of the water is driven off. During this further mixing operation carried on in the presence of the asphalt, the inverted emulsion is produced, and the hydraulic shear effect of the tenacious emulsion together with the mechanical action of the mixing elements causes the paper stock to be thoroughly disintegrated'in a short time to the form substantially of elementary fibres thoroughly coated with and distributed through the emulsion.

When the mixing and disintegrating operations have been carried on to the point where substantially complete disintegration of the fibrous material has been attained, the plastic composition may be discharged from the mixer, and is then ready for use in the production-of certain articles, such as paving blocks, which are shaped merely by pressing operations. It the material is to be used in the production of articles formed by extrusion, such as roofing elements and the like, it is desirable to add a further quantity of asphalt to the mass and continue the mixing operation until the additional asphalt has been thoroughly mingled with the charge.

For roofing materials, tlig.,ladditional quantity of asphalt so added to a batch, as above described, may begabout 220 pounds? Upon removal of the plastic mass from the mixer, the asphalt and water remain combined in the form of the inverted emulsion previously referred to, and the fibres are moist, soft, and pliable. Preferably, water is present in the composition until after the completion of the shaping operations, and its presence is particularly desirable when the composition -is to be shaped by extrusion. As soon as the shaping operations are completed, the water-is driven oft as rapidly as possible, and the composition thereupon becomes hard and relatively stifi. With the removal of the water, the fibres lose their pliability and softness and become stiff, retaining without strain the shape to which they have been conformed. In this drying of the fibres, they contract, and

this increases the interlacing thereof with the result that rigidity is imparted to the product and the tendency to plastic flow is practically eliminated.

If water were not used in making the new product, the fibres in the material as produced would be dry, and would have a rigidity such as to cause them to be subjected to strain in the forming operations. As a result, the formed material would have an inherent weakness and would tend to become deformed when subjected to a temperature sufficient to soften the binding agent. The presence of the water thus not only conditions the fibres so that they may be readily worked, but in addition, its combination with the asphalt with the formation ofthe inverted emulsion, makes possible a better disintegration of the waste paper stock. The production of the emulsion has the further advantage that the fibres become thoroughly coated by it, and they are similarly coated by the binding agent when the emulsion is broken down by the driving off of the water.

The use of the promoting and stabilizing agents, such as lime, and the soap-forming materials, such as rosin, in the production of the new composition affords several advantages. These agents and materials combine to form a soap, and this soap assists in the production of the water-in-asphalt emulsion. In addition, the soap improves the waterproof qualities of the finished product and lessens its tendency to soften under heat.

The .new composition may have varying physical characteristics, depending on the proportions of fibrous material and binding medium employed, and on the melt point of the binding medium used. In all forms, the material has a low thermal-conductivity and a low susceptibility to temperature changes, and it is non-absorptive and fire-resistant. It can be made rigid without being brittle, so that it can be nailed, cut, or saw-n without difliculty, and it has practically no tendency to flow when subjected to a temperature in excess of the melt point of the binding material, as is shown by the fact that a shingle of the new composition, supported at one end only, is not elongated to any considerable extent by its own weight when exposed to such a temperature.

For most purposes, the new composition may contain an amount of the binding medium varying from about 50 percent to about 10 percent of the weight of the hardened composition, and an amount of fibrous material varying -from about 30 percent to about 50 percent of the weight referred to. The water employed in making the composition is ordinarily about equal' in weight to the binding medium present at the beginning of the production of the inverted emulsion, and although some water is driven oif in that operation, enough remains to maintain the emulsion until the forming operations are completed.

The method of producing the new material by the use of a Banbury mixer permits production at a low cost, since the mixing operation is of short duration and, therefore, at a high output rate. Also, the cost of the product is low because a relatively inexpensive asphalt may be employed, andit is not necessary either to heat the asphalt or to employ solvents to reduce its viscosity before it is introduced'into the mixer.

A further advantage aiforded by the new method is that during the final disintegration of the paper stock to elementary fibre form, the

fibres are separated from one another largely by a wiping .action carried on by the working or no fibrillae;

I claim:

'1. A composition of matter bituminous binding medium and water combined to form an emulsion in which the binding medium is in the continuous phase and 'the water in the disperse phase, a substance efi'ective to stabilize said emulsion distributed therethrough, andpaperstock disintegrated to the form substantially of individual fibres distributed substantially uniformly and homogeneously through said emulsion, said fibres being interlaced and coated and bound together byv said binding medium.

' '2. A composition of matter which comprises a bituminous binding medium and water combined to form an emulsion in'which the binding medium is in the continuous phaseand the water is in the disperse phase, paper "stock disintegrated to the form substantially of individual fibres distributed substantially uniformly and homogeneously through said emulsion, said fibres being interlaced and coated and bound together by the emulsion, and an alkaline substance and a soap-forming substance combined to form a water-insoluble soap, said soap being present throughout said emulsion in a small amount relative to theweight oi the binding medium.

3. A composition of matter which comprises a bituminous binding medium and water combined.

to form an emulsion in which the binding medium is in the continuous phase and the water is in the disperse phase, paper stock disintegrated to the form substantially of individual fibres dis-- tributed substantially uniformly and homogeneously through said emulsion, said fibres be ing interlaced and coated and bound together by, said emulsion, and a lime-rosin soap distributed throughout said emulsion and 'present in a small amount relative to the weight of the binding medium.

4. A composition of matter which comprises a bituminous binding medium and water combined to form an emulsion in which the binding medium is in the continuous phase and the water is in the disperse phase, paper stock disintegrated to the form substantially of individual fibres distributed substantially uniformly and homogeneously through said emulsion, said fibres being interlaced and coated and bound together by said emulsion, and a lime-rosin soap distributed throughout said emulsion and present in an amount not substantially greater than 10 percent of the weight of the binding medium.

5. A composition of matter which comprises a bituminous binding medium and water combined to form an emulsion in which the binding medium is in the continuous phase and the water is in the disperse phase, paper stock disintegrated to a 'the form substantially oi'gindividual fibres distributed substantially uniformly and homogeneouslythrough said emulsion, said fibres being which comprises a interlaced and coated and bound together by said emulsion, and a lime-rosin soap distributed throughout said emulsion, said binding medium, fibrous material, and soap being present in about the proportions of from twenty-two to fortyfour parts, twenty-two parts, and two parts, respectively. v 6. A method of making a composition of matter which comprises introducing paper stock,-

actions to efiect disintegration of said stock and v to cause the lime and rosin to combine to form a soap, introducing a bituminous binding medium into said mixing chamber, and continuing said operations on the contents of said chamber to cause the water and binding medium to combine into an emulsion in which the binding medium is in the continuous/phase and the water is in the disperse phase and to efiect disintegration of said stock in the presence of said emulsion to the form substantially of individual fibres distributed substantially uniformly and homogeneously through said emulsion and coated thereby.

7. A method of making acomposition of matter which comprises introducing paper stock, water, and a small quantity of lime and rosin into a mixing chamber, subjecting the materials in said chamber to rolling, rubbing, and smearing actions to efiect disintegration of said stock to cause the water and binding medium to combine into an emulsion in which the binding medium is in the continuous phase and the water V is in the disperse phase, and to effect disintegration of said stock in the presence of said emulsion-to the form substantially of individual fibres distributed substantially uniformly and homogeneously through said emulsion and coated thereby, subsequently introducing a further quantity of binding medium into said mixing chamher, and continuing said operations to cause said further, quantity of binding medium to be thoroughly mixed with the contents of said chamber.

8. A method of making a composition of matter which comprises disintegrating paper stock in the presence of moisture, adding to the reduced mass a bituminous binding medium and substances which promote the formation of and stabilize emulsions of water in the binding medium,' and continuing the disintegrating operaduced mass a bituminous binding medium and substances which promote the formation of and stabilize emulsions of water in the binding medium, continuing the disintegrating operation to produce an emulsion in which the water is in the internal phase and the binding medium is-in the continuous phase, and to reduce the paper stock to the form of fibres distributed substanti- "ally uniformly and homogeneously through said emulsion and thereafter adding a further quantity oi the binding medium and continuing the disintegrating operation to cause the additional quantity of binding medium to be thoroughly mixed with said emulsion.-

10. A composition of matter which comprises a. bituminous binding medium, water, and a soup of a. polyvalent alkaline material combined to form a stabilized inverted emulsion in which the 7 binding medium is present in the continuous phase and the water is in the disperse phase, and paper stock reduced substantially to the form oi individual fibres distributedsubstantially unitonnly and homogeneously through said emul- 8102!, said fibres being interlaced and coated and bound together by said emulsion.

THOMAS ROBINSON.