Patented Oct. 1, 1946 7 2,408,682 ' ’ UNITED STATES-PATENT OFFICE Y ADHERING 0F POLYVINYL ALCOHOL COM POSITIONS TO OTHER MATERIALS ' Charles Arthnr'l'ortcr, Nutley, N. J., assignorto Resistoiiex Generation, Bellevllle, N. 1.; a cor poration of New York ' No Drawing. Application December 28, 1944 ' Serial No. 570.222 12 Claims. . _. (01. 154—139) ' This invention relates to the adhering of poly vinyl alcohol compositions to other materials, more particularly to ?brous materials.‘ ethylene diamine, diethylene triamine, triethyl ene tetramine, and tetraethylene pentamine. These materials are preferably used as aqueous 4 In the making of a wide variety of mechanical goods from polyvinyl alcohol compositions, it. is frequently necessary or desirable to laminate the plastic composition with one or more layers of ?brous material, such as textile fabric or paper, solutions in concentrations of from about 5% tov 15%. The best range of concentration appears ' to be between about 5% and- about ‘7%. The textile or other ?brous material may bev _ immersed in the“ solution until it is thoroughly > or to incorporate in the material strengthening wetted, removed and dried at room temperature ' members in the form of cords or threads. of nat 10 to the point where it is Just slightly 'damp and ural or synthetic ?ber, or inserts of ?berboard ~ and the like. i then laminated with the polyvinyl alcohol com position and bonded thereto in the usual way with - It is particularly desirable that there be a ?rm heat and pressure. Wetting can be accelerated bond and strong adhesion between the polyvinyl by the use of wetting'agents and may be accom-' alcohol composition and the ?brous reinforce 15 plished by brushing or spraying as well as by dip ment, especially in those cases where the product is subjected to ?exing. ping. By not completely drying the layer of re One of the di?lculties -. _ inforcement, 'or.by moistening it slightly if it has heretofore encountered has been insu?lcient ad been completely. dried, the adhering toit of the ' hesion with the result that in use the plastic : composition has separated from its reinforcing 20 adjacent layer of polyvinyl alcohol composition during molding is facilitated. members. . The present invention appears to improve and facilitate the adhesion of polyvinyl alcohol com ' _ _ . Laminated sheets of reinforced polyvinyl al cohol compositions may be made by placing al- _ positions to all types of ?brous material, includ ternate layers of the plastic and ‘?brous rein ingnatural ?bers ‘of animal or vegetable origin as - forcement in a mold and subjecting them to heat. 25 well as synthetic ?bers such as rayon. The ?-. and pressure. In order'to obtain the proper ad brous materialmay be in the form of threads, hesion of'the layers to one another, it has here cords, textile ‘fabrics, paper, cardboard, ?ber tofore been necessary to control the pressure and board and the like manufactured products, or in temperature within close limits, slight deviations the formiof a natural product such as wood 'or therein resulting in imperfect adhesion. An 30 leather. other di?iculty has been breakage of the ‘reinforc ing layersv such as textile fabric and paper during molding, ’due apparently to high friction between ~ _ " ' ' ‘ tion, all of the water-soluble products resulting 35 from the partial hydrolysis of polyvinyl esters sure which causes a certain amount of ?ow of the plastic relative: to the reinforcement. ' _ which may be of di?erent degrees of polymeriza the polyvinyl alcohol composition and the fabric - layer during the application of the molding pres \ The term polyvinyl alcohpl, as used herein, in-. cludes, in addition to pure polyvinyl alcohol, and water-soluble partial derivatives of polyvinyl ' alcohol however formed. Polyvinyl alcohol is usually made by the partial or complete hydrolysis ~ The objects of the present invention are gen era'lly to improve the adhesion between ?brous of polyvinyl acetate and the commercially avail materials and polyvinyl alcohol compositions, to 40 able varieties vary in their degree of hydrolysis, enable the securing of more perfect adhesion as indicated by the percentage of ester saponi through a wider range of pressures and temper ?ed or by a saponi?cation number,-as well as in atures. to eliminate breakage of reinforcing lay ers during molding, and to produce more perfect products. , 45 vinyl alcohol, as herein de?ned. _ The present invention resides in the discovery .- that greatlv improved results are obtained if the ?brous material-is subjected, preliminary to the bonding operation, to the action of a dilute aque ous solution of a linear ethylene amine having the 50 formula their viscosities in solution. The invention has been found to be applicable to all types of‘ poly ‘ ' The following speci?c examples will illustrate the invention and show the advantages to 'be de rived therefrom: , Exlmrns 1 A six inch square of muslin was‘ soaked in a 7% aqueous solution of tetraethylene pentamine for about 1 minute and dried at room temperature wherein n is a whole number of 4 or less. The until it retained only a slight dampness. The compounds comprised within this de?nition are 65 thus treated fabric was used as an inter-layer be-_ ' 2,408,682 3 tween two milled sheets of , polyvinyl alcohol _4 - Exlmrm 3 composition about 3,!" thick, produced by the Sheets of about 1/32nd of an inch in thick method disclosed in U. S. Patent No. 2,177,612 ness were milled from a mixture having the fol from the following ingredients, the proportions being expressed as parts by weight: lowing composition, parts being by weight: Polyvinyl alcohol (91-94% saponi?ed, me dium viscosity) _______________________ __ 100 Polyvinyl alcohol (91-94% saponi?ed me Glycerol _______________________________ __ dium viscosity) _______________________ __ 100 Glycerol ____________________ ________' ____ __ Formamide 35 10 __________ __, ________________ __ '1 Water ____ ______________________________ __ 36 35 Formamide ______________ __- ____________ __ 10 Water ____ __. ___________________________ __ 40 A six inch square of kraft paper was soaked in a 7% aqueous solution of tetraethylene pentamine The assembly of textile and milled sheets was until thoroughly wetted. The paper was dried placed in an open mold in a platen press, heated at room temperature until it had only a damp feel 15 to 260° F. in four minutes, then subjected to a to the touch. It was then placed between two pressure of 250 lbs. per sq. in. and cooled imme pieces of the above milled sheet and exposed to diately while still under pressure. heat and pressure in an open mold, as in Ex The adhesion of the polyvinyl alcohol compo ample 1. The adhesion between the paper and sition to the textile was excellent and the textile the polyvinyl alcohol composition was very good 20 was not damaged in any way. Carrying out the and the paper was not ruptured; When the pro above procedure in exactly the same way except cedure was repeated in the same manner except‘ that the treatment of the fabric prior to lami that the treatment of the paper with the above natingv was omitted, very poor adhesion was ob mentioned solution was omitted, the adhesion tained. vIn repeating the latter procedure with was very poor. An increase of temperature and' an increase in the temperature and pressure in 25 pressure improved, the adhesion somewhat but an attempt to improve the adhesion, the fabric ruptured the paper in several places. interlayer was ruptured in places during molding. Moistening the ?brous sheet of fabric or paper with water will somewhat improve the adhesion EXAMPLE 2 between it and the polyvinyl alcohol composition 30 under molding conditions but this expedient is not satisfactory as the presence of water tends to produce blister formation during molding and, . since it does not decrease the friction between While treatment of the'surface to be adhered to the polyvinyl alcohol composition with the linear ethylene amines of the invention has been found to improve the adhesion of such composi 35 the paper or fabric and the polyvinyl alcohol composition, it does not eliminate the .tendency tions made with any grade of polyvinyl alcohol, it has been found to produce the best results‘ with compositions made from thosegrades of polyvinyl alcohol which are soluble in cold water, for example the grade which is 85-88% saponi fled and has a high'viscoslty. To take advan of the pressure to rupture the ?brous sheet. One of the particular advantages of the ethylene amlnes'described herein is their lubricating eifect ‘ during molding which entirely eliminates ruptur tage of this discovery when molding articles comprising other grades of polyvinyl alcohol, ing of the reinforcement. The best results have ‘been obtained from the higher members of the series of ethylene amines thin intermediate layers of compositions made with the cold-water-soluble types of polyvinyl described above, namely triethylene tetramine , alcohol may be used. and tetraethylene pentamine and their use is therefore preferred although all of the com pounds named have been found to be useful for Milled sheets of the fol lowing compositions were prepared, parts by weight: Composition A the stated purposes, the differences being a mat- _ 50 Polyvinyl alcohol (85-38% saponi?ed, high viscosity) ____________________________ __ 100 Glycerol _______________________________ __ so Formamide ____________________________ a- 20 Water ________________________________ _'__ ll) Composition B ter of degree only. Since the foregoing examples are merely illus trative of the invention, it is‘ to be understood that it may be practiced otherwise than as herein speci?cally set forth and that the invention is to be construed broadly within the purview of 55 the claims. . ‘ ' What is claimed is: l. The method of making a composite product comprising polyvinyl alcohol composition and Polyvinyl alcohol (at least 98.5% saponi?ed, ~medium viscosity) ____________________ __ 10o Glycerol _______________________________ __ 5o Formamlde __________ __' ________________ __ 20 Water _________________________________ __ 55 fibrous. material in adhering'relationship which 0 comprises the steps of treating the ?brous me. terial with a linear ethylene amine having the formula ' in which n is a whole number of 4 or less, and 65 thereafter applying the polyvinyl alcohol compo sition to the thus treated ?brous material. aqueous solution of triethylene tetramine and 2. The method of claim 1 wherein the linear dried at room temperature until just slightly ethylene amine is applied as an aqueous solution moist. It was then placed between two layers and the ?brous material is substantially dried be of'mllled sheet (formed as in Example 1) of Composition A and this sandwich was then placed 70 fore application of the polyvinyl alcohol composi tion thereto. between two layers of similar milled, sheet of 3. The method of claim 1 wherein the applica Composition B. The whole was then molded in tion of the polyvinyl alcohol composition to the an open mold under the conditions described in ?brous material is made by means of heat and Example 1. Adhesion to the textile was excellent 75 pressure. and there was no damage to the textile. A six inch square of muslin was soaked in a 5% 2,408,082 5 4. The method 01' making a, composite article comprising ?brous material and polyvinyl alco hol composition comprising the steps of treating said material with a solution of triethylene tetra mine, evaporating most of the solvent, associat ing the thus treated fibrous material with poly vinyl alcohol composition, and applying heat and pressure to adhere said material and composition. oi’ cold-water-soluble polyvinyl alcohol, and sub jecting the composite to heat and pressure where by the materials are caused to adhere together. 7. A composite product comprising a layer of ?brous material containing a linear ethylene amine having the i'ormula wherein n is a whole number of 4 or less, and _ 5. The method of making a composite article 10 a layer of polyvinyl alcohol composition, said together. comprising ?brous material and polyvinyl alco hol composition comprising the steps of treat layers being adhered together. 8. A composite product comprising a layer of ?brous material containing triethylene tetra ing said material with a. solution of tctraethylene mine, and a layer‘ of polyvinyl alcohol composi pentamine, evaporating most of the solvent, asso .ciating the thus treated ?brous material with 15 tion, said layers being adhered together. 9. A composite product comprising a layer of polyvinyl alcohol composition, and applying heat ?brous material containing tetraethylene pent and pressure to adhere said material and compo sition together. » ' > amine, and a layer of polyvinyl alcohol composi 6. The method of forming a composite prod uct comprising fibrous material and polyvinyl tion, said layers :being'adhered together. alcohol composition‘which comprises treating said ?brous material is textile fabric. ' ‘ material with an aqueous solution of a linear‘ ethylene amine corresponding to the formula I the ?brous material is paper. Hmo-CmCmNHM-n wherein n is a whole number of 4 or less, evapo rating most 01’ the solvent, associating the thus vtreated material while damp with a composition 10. A product according to claim 7 in which the 11. A product according to claim 'I in which . ' 12. A product according to claim 7 in which the polyvinyl alcohol composition is of the cold 25 water-soluble type. enemas AR'I'HUR PORTER.