Патент USA US3085916код для вставки
April 16, 1963 Filed July 27, 1959 c. HARMON x-:T AL REINFORCED PAPER 3,085,906 2 Sheets-511991l 1 M ATTORNEY April 16, 1963 c. HARMoN ET AL 3,085,906 REINFORCED PAPER Filed July 27, 1959 2 Sheets-Sheet 2 T: :1.13. 2a Ñ 7.15015?, È QQ I | /0 20 l l 30 40 I .50 l 60 l l 70 ¿0 | l 90 /00 ß /ìçóf' ey/m//à/f à 1 ATTO R N EY States 1 3,085,906 REINFORCED PAPER Carlyle Harmon, Scotch Plains, and Richard M. Smith, New Brunswick, NJ., assignors to Johnson & Johnson, a corporation of New Jersey Filed July 27, 1959, Ser. No. 829,662 11 Claims. (Cl. 117-122) EQ@ 3,085,90â Patented Apr. 16, 1963 2 drated woodpulp fibers, rubbery binder solids portions distributed substantially uniformly throughout the web, and a multiplicity of relatively large flexible and tough thermoplastic reniforcing members distributed substan tially uniformly throughout the web in bonding relation l with the woodpulp übers. The woodpulp fibers are ar ranged in overlapping crossing relation with one another so as to define a multiplicity of minute interstices between them. The relatively large reinforcing members define This invention relates to unified paper backings for various uses, more particularly to flexible paper backings 10 a corresponding multiplicity of space `between the members unified by impregnating the paper with rubbery binder solids until the paper is internally strengthened and is in the web. The average distance across the spaces be particularly suitable for use as a backing material for than the average distance across, or the size, of the rela products such as pressure-sensitive adhesive masking tapes and the like. Backings of this type, particularly those which must be used in flexible pressure-sensitive adhesive tapes, must tively minute interstices between the woodpulp fibers so that several of these interstices generally are located in each of the spaces between the reinforcing members. possess a number of important physical properties to a tween the reinforcing members is considerably greater The rubbery binder solids portions hold the woodpulp fibers together between reinforcing members. The structure of the reinforced web product of this high degree. These include flexibility, delamination strength, tensnile Strength, 'and various other properties 20 invention is determined to a large extent by the relative sizes lof the woodpulp fibers and the thermoplastic rein such as edge tear strength, elongation, abrasion resistance forcing members, and the relative proportions by weight wet and dry, and the like. Various attempts have been -of >these components in the web. The woodpulp fibers made to build all of these properties into paper backings are relatively small when compared with the reinforcing which are particularly suitable for pressure-sensitive ad hesive tapes and similar products. Backings of this gen 25 members, i.e., the woodpulp fibers are in the range of about 0.04 to 0.4 mils in thickness and about 0.4 to 0.8 eral type are described in United States Patents 2,726,967; mils in width, and are less than 1A inch in length nor 2,848,105; and 2,848,355. All of these patents describe mally within the range of about 80 to 240 mils, while the the problem in some detail and provide various ways for reinforcing members are in the range of l to 35 mils in unifying the backing 'sheet by impregnating it with a rubbery binder material, as well as different ways of im proving the binder and enhancing the effectiveness of the fiber binder relationship. 30 cross dimension and may be as long `as an inch or more, depending upon shape factors such as their length-to width ratio. For instance, if they are in the form of rods having a more or less circular cross section and a length to-width ratio of 2 to l, normally over l0 to l or more, as Well as flexibility. For instance, it has been common 35 their cross dimensions may fall within the range of about In products of this general type, it is highly desirable to improve delamination strength and tensile strength, in the manufacture of backings Afor pressure-sensitive ad hesive tapes of vthe type described in the above patents to impregnate the starting paper web with 80 yto 100` percent l to 5 mils; and they may be between about ïÁgg and l inch or `over in length, although rods below about 1A inch in length may be preferred. However, when the length~to-width ratio of the reinforcing members is de Normally, this involves “saturating" 40 creased until length `and width become more nearly equal or more of a rubbery binder material by weight of the dry paper fibers. the paper web, ie., substantially filling in the interstices to each -other and the members are in the form of gran~ ules, the cross dimension of the reinforcing members may be between about 5 and 35 mils. binder solids. There is a tendency of such papers either In a given product according to this invention, the to become stiff or too rubbery, either of which may be 45 sizes of the reinforcing members and the woodpulp fibers undesirable for various applications. are of different orders of magnitude, i.e., the individual Accordingly, it is an object of this invention to provide reinforcing members are at least about 5, preferably l0 or an improved unified paper backing which possesses ten more, times larger in cross-sectional area than the indi sile strength and delamination strength to a high degree vidual woodpulp fibers. Thus, even if equal proportions and in addition possesses a high degree of flexibility. Another object of the invention is to provide such a 50 of the woodpulp fibers and reinforcing members are used, the above-described relationship exists wherein the spaces backing which possesses these three properties to a high between the reinforcing members 4are considerably larger degree and which contains a comparatively low propor than the interstices between the woodpulp fibers, and the tion of rubbery binder solids, i.e., normally not above binder solids portions form a multiplicity of bonds be 50 percent of the weight of the paper fibers, although as high as 70 or more percent of the binder solids may be 55 tween the woodpulp fibers in the spaces between the re~ formed between the interlacing paper fibers with the employed for certain applications. Still another object of the invention is to provide an improved unified paper backing for pressure-sensitive ad inforcing members. However, the reinforcing members and the binder solids are applied in the web in certain definite proportions which contribute to the desired struc ture. Normally, the over-all weight of the reinforcing improved tensile strength, delamination strength flexibil 60 members with respect to the dry woodpulp fiber solids hesive tapes, such -as masking tapes, which possesses ity and openness when compared with prior art backings falls within the range of about 5 to 30 percent, although of the same general type, and yet contains a much lower as little as 2 or 3 percent and as much as 50 percent yof percentage of rubbery impregnant solids. the reinforcing members by weight may be used with A further object of the invention is to provide im desirable results for certain applications. The range for proved paper backings of the type described which are 65 the reinforcing members of 5 to l5 percent by weight is more economical than prior art backings of the same general type. particularly preferred for products such as paper backed pressure-sensitive adhesive tapes such as masking tapes and the like. As mentioned above, the normal range for Other :and further objects of #the invention will be ap parent from the following description and claims taken the rubbery binder solids portions, particularly for pres together with the drawings. 70 sure-sensitive adhesive tapes and the like, is between about The backing of this invention comprises a web or 20 to 50 percent by weight of the woodpulp fiber solids network of moderately hydrated or substantially unhy and reinforcing members, although binder solids may be 3,085,906 3 4 applied within the range of about 10 to 70 percent or more by weight on the same basis for particular applica tions. While the exact reason for the improved delamination strength of backings according to this invention is not deñnitely known, it is possible to offer more than one possible explanation. For instance, as shown best in FIG. When substantially unhydrated woodpulp fibers and fiexible and tough thermoplastic reinforcing members bearing the above-described size and weight relationship 2, it is believed that the binder members 14 act some what like large logs in a mill pond or marbles in a match box to cause certain of the woodpulp fibers 11 to be to one another are distributed in a web in the propor come upended or more angularly disposed with respect tions by weight set forth above, the desired structure of to the plane of the web so that a fairly high percentage of the backing of this invention is obtained. In this struc ture, the spaces between the reinforcing members are con 10 woodpulp fibers have a component in the direction of the thickness of the backing. This should increase delamina siderably greater in size or cross dimension than the size tion strength, since it becomes necessary to tear more or cross dimension of the interstices between the over lapping crossing woodpulp fibers. fibers to delaminate the web, as opposed to tearing fewer fibers and then separating laminar sections of the web. The structure of the fabric of this invention will be explained and may be better understood by reference to 15 Another way of saying this is that the presence of the relatively large reinforcing members 14 causes a higher the following drawings wherein: degree of woodpulp fiber orientation in the direction of FIGURE 1 is a schematic plan view of a paper web the thickness of the web. This also may tend to increase according to this invention as one embodiment may the flexibility of the web. appear; It also is possible that a high percentage of this in FIG. 2 is a schematic sectional view along the line 2_2 creased delamination strength may be due to the fact of FIG. 1; that the fiexible and tough reinforcing members l14, them FIG. 3 is a graph of tensile strength versus percent selves, extend through a high proportion of the thickness impregnation for a paper web according to Example V of the web as illustrated in FIG. 2. Thus, in order to herein; PIG. 4 is a graph of Gurley stiffness versus percent 25 delaminate the backing, it is necessary to rip through a impregnation for the paper web of FIG. 3; and FIG. 5 is a graph of delamination resistance versus large number of the reinforcing members 14. The increased tensile strength of backings according percent impregnation for the paper web of FIG. 3. to this invention also may be due to the fact that the `Referring to the drawings, relatively short and small reinforcing members 14, themselves, possess considerable woodpulp fibers 11 are arranged in overlapping crossing 30 strength and act like the steel rods in reinforced con relation with one another so as to form a multiplicity of crete to add tensile strength to -the web. interstices 12 between them. The woodpulp fibers are In forming backings according to this invention, it is bonded together by rubbery binder solids portions 13 distributed substantially uniformly throughout the web, preferred to distribute the reinforcing members in the web during the papermaking step. Normally, this step as well as a multiplicity of relatively large rod-shaped 35 involves distributing the woodpulp fibers in a substan fiexible and tough thermoplastic polymeric reinforcing tially nonhydrated or moderately hydrated state in wa members 14 distributed substantially uniformly through ter to form an aqueous slurry of woodpulp fibers and out the web. mixing the proper proportion of thermoplastic reinforc It is believed that the reinforcing members 14 may per ing members with the woodpulp fibers in the slurry until form various functions in the web structure. First of all, 4.0 they are distributed substantially uniformly in the slurry each of the reinforcing members 14 bonds a large num and intimately intermingled with the woodpulp fibers. ber of woodpulp fibers 11 which pass through or into The slurry is then drained through some sort of collect contact with the member. As shown most clearly in FIG. ing means for making paper such as a Fourdrinier wire, 2, the individual reinforcing members 14 entrap a num a drum screen, a hand sheet mold, or the like to form a ber of adjacent or contiguous woodpulp fibers 11 in the 45 paper web. After drying and pressing as is conventional plane of the web and perpendicular thereto, or through in papermaking, heat and pressure are applied to the web the thickness of the web. The woodpulp fibers 11 are held containing the reinforcing members in such a way as to firmly in the individual reinforcing members 1-4 since the soften and preferably fuse the thermoplastic reinforcing woodpulp fibers passing through each member 14 are in members and press them through the thickness of the contact with the material of the reinforcing member along web so that they entrap a large number of woodpulp a high proportion of the length of the woodpulp fibers 11. fibers. Temperature and pressure are controlled care The reinforcing members 14 define a multiplicity of fully so that the material of the reinforcing members spaces 15 between them; and the average distance across does not iiow too freely and cause the members to lose the spaces is considerably greater than the average their shape. `For instance, if temperature is too high, distance across the interstices 12, or the size of the inter stices, formed between interlacing woodpulp fibers 11. Thus, several of these interstices 12 generally are located in each of the spaces 15 formed between the reinforcing members 14. In a sense, the web is “interrupted” by the reinforcing 60 members 14 so as to form a multiplicity of web “islands” corresponding to the web areas in the spaces 1S between under certain pressures surface tension may cause the material in the reinforcing members to “ball up”; and of course if pressure is too high, it will squeeze the reinforc ing members and fiatten them out to too great an extent. It is inevitable in this process that the reinforcing mem bers be ñattened to a certain extent, and allowance can be made for this. Thus, the cross dimension of the re inforcing members in the resulting fabric may be as great as twice that of the rods or granules from which they are formed, although the increase in cross dimen islands are formed by the woodpulp fibers 11 in the spaces 65 sion due to the application of lheat and pressure during 15 and the rubbery binder solids portions 13 which hold the bonding of the reinforcing members normally is not these fibers together to form a connected network struc this great. ture. The reinforcing members 14 defining the islands After the bonds between the reinforcing members and may be compared to hinges between islands which provide the woodpulp fibers have been formed and the web has elements of fiexibility scattered throughout the web struc 70 been allowed to cool to permit the bonds to become set, ture. It is believed that the hinged island structure just the rubbery binder solids may be applied thereto. Nor described may contribute to the improved fiexibility of mally, this is accompiished by impregnating the web backings of this invention, although other factors such as with an aqueous dispersion of a natural or synthetic rub the lower percentage of binder solids portions present and fiber orientation also may affect iiexibility. 75 bery latex, or by impregnating it with a natural or syn the reinforcing members 14, which are joined together by the reinforcing members. Continuing this analogy, the 3,085,906 5 thetic rubber composition deposited from solution in a volatile organic solvent. These methods are taught in United States Patents 2,726,967 and 2,236,527, respec tively. Woodpulps, the fibers of which are suitable for use in producing backings in accordance with this invention, include relatively long fiber kraft-type pulps, such as, Duracel pulp sold by the Canadian International Paper Company. The pulp may be either unbeaten (unhy 6 polymers, copolymers of vinyl chloride with other mate rials lsuchas vinyl acetate and vinylidene chloride, chloro prene rubber and various other similar elastomeric poly mers. Copolymers of butadiene and unsaturated nitriles, such as yacrylonitrile and the like, have been found to be particularly suitable for this purpose. `Before application to the fibrous web, the rubbery binder ysolids may be in the form of relatively small particles ranging in size from «about 0.004 to 0.2 mil in cross sec tion, preferably not `above ‘about 0.04 mil, normally hav ing a length-to-width ratio in the neighborhood of 1:1. As the rubbery binder is applied to the web formed by it has a Schopper-Riegler freeness of at least about 600 the woodpulp fibers 11 and the reinforcing members 14, cc. or more. Thus, Webs formed from the fibers of such the rubbery binder solids portions 13 yare formed between a pulp are open and comprise fibers overlapping and crossing one another and forming myriad relatively 15 the Woodpulp `fibers. The rubbery binder material may remain in the form of the original relatively small latex minute interstices between them. As mentioned herein particles in which it is deposited. However, as the amount before, the individual woodpulp fibers are in the range of the rubbery binder in the web is increased, the original of about `0.104 to `0.4 mil in thickness and about 0.4 to drated) or slightly hydrated but not to the extent that it is not definitely fibrous in form. Generally speaking, latex particles tend to'join one another and form an at 0.8 mil in width, and generally are less than about 1A inch, say about S0 to 240 mils, in length. From the 20 least partially continuous rubbery matrix with the rub bery binder solids portions connecting the woodpulp fibers above, it is apparent that the woodpulp fibers are some in the areas 15 between the binder members 14 being in what flat, or ribbon like, in shape. They may be more the form of agglomerates which may be somewhat film or less straight or somewhat curled and kinked as may like in character. As the concentration of the rubbery result from being subjected to treatment such as de scribed in United States Patent 2,516,384 to provide 25 binder solids portions is increased, the Vdeposited binder material becomes less particle-like and more like a con curlated fibers. tinuous matrix in nature. The relatively flexible and tough thermoplastic rein Backings according to this invention have many uses. forcing members of this invention preferably are se As mentioned hereinbefore, their qualities make them par lected from among a number of long-chain polymeric materials which form flexible and tough solid granules 30 ticularly suitable as backings for pressure-sensitive ad hesive tapes, particularly pressure-sensitive adhesive mask or rods. Nylon `6 comprising polycaprolactarn gives par ing tapes and the like. They also are suitable for pressure ticularly good results when used as the material for the sensitive packaging, identification, labeling, patching or reinforcing members of this invention. Other materials, mending, splicing, strapping, bundling and decorative which may be employed for the reinforcing members, include Nylon -1\1 such as sold under the trademark 35 tapes and the like and similar tapes of a non-pressure sensitive nature. In addition to its use in tta-pes, ‘backings “Rilsan” by Organico, S. A., of France, Saran, poly of this invention ‘are particularly useful in sandpapens, amides other `than `Nylons y6 `and l1, polyvinyl chloride, protective papers, and similar fibrous web materials where polyethylene, polyurethane, polystyrene, polyvinylidene cyanide, plasticized cellulose acetate, plasticized ethyl .40 in flexibility and toughness are required. Normally, backing webs according to this invention cellulose, and the like. have »a basis weight between about -25 to 30 pounds; Íi.e., The size of the reinforcing members may vary over a wide range. If the reinforcing members are in the shape of rods, prior to fusing, they normally would fall 480 sheets `24 inches by `36 inches weigh this amount. However, this invention is not limited to this range of within the range of about 6.5-‘100 denier, correspond 45 weight. For instance, the flexibility ‘and therefore the conformability of protective papers having a basis weight ing to about 0.0005-0‘004 inch in diameter prior to fus ybetween about `60 and I80 pounds may be increased sub ing for the flexible and tough thermoplastic materials of stantially in accordance with this invention without de this invention, and 1,4»,2 to 1 inch in length. Preferably, tracting from other desirable properties. In the same the rods would be between about 10 and 60 denier, cor way, backings ‘accor-ding to this invention may responding to about 00012-00034 inch in diameter 50 have 'asandpaper basis weight as high :as 150 pounds. prior to fusing, and in the neighborhood of 1A inch or Various embodiments of reinforced papers in accord less in length. If the reinforcing members of this in ance with this invention Will be illustrated in the following vention are in the shape of granules, prior -to fusing, they examples. normally would be of such a size that 7 0 percent of the Example I granules would not pass through a 200 mesh screen. 55 Preferably, the majority of the particles are of a size that A resin-'bonded backing is made up using curlated Sunila would not pass through a 1100 mesh screen. This means pulp beaten to a Schepper-Riegler freeness of 870 cc. and that generally speaking the average granule size will be waste Nylon `6 rods averaging about .054 inch in length within the range of about 0.004-0‘015 inch in diameter .and ‘about i60 denier per filament. Sunila pulp is a rela prior to fusing. Rods and granules outside the indicated 60 tively long semibleached kraft-type soft woodpulp im ranges may be used provided that they are at least about ported from Sweden and sold by Pulp Sales Corporation 5, preferably 10 or more, times larger in cross-sectional of New York. The materials are combined in an 8-inch area than the woodpulp fibers with which they are used. diameter circular sheet mold in the following proportions: The rubbery solids portions may be supplied from various natural yand synthetic elastomeric materials, or 65 mixtures of an elastomeric component with -a thermoset ting component, such as are 4described in United States Patents 2,848,105 land 2,848,655. As mentioned herein Curlated Sunila Pulp ....................... _- Dry. Dryy Weight, g. Percent 1. 275 85 Nylon 6 Rods _______________________________ ._ 0.225 l5 before, the elastomer, or elastomeric mixture, may be in the form of :an aqueous dispersion of a synthetic rubbery 70 The wet sheet is removed from the sheet mold with a latex or a natural or synthetic rubber composition in solu blotter, pressed at 2.3 pounds per square inch, and dried. tion in a volatile organic solvent. Suitable synthetic rub Then, it is bonded in a Carver press at 200 pounds per bery latices may comprise polymers of butadiene and square inch pressure and 425° F. for l0 seconds. 'The other conjugated dienes and their homologues, and co polymers «and tripolymers based thereon, vinyl chloride 75 finished sheet basis Weight (including the Nylon 6) is «28 3,085,906 8 'Z pounds -per ream (l ream=480, 24 inches x 36 inches). Example I in such a way that the percent impregnation The bonded sheet is impregnated with a synthetic im is 45% with the following results: pregnant comprising a rubber latex and la synthetic resin curing agent in accordance with the following_ formulation g Delamlnation and then is dried and cured. The percent impregnation, 5 Web containingresistencia, l based on the weight of the unimpregnated sheet, is 10.3%. Ouncâllìcll, ucl » Ingredients Manufacturer io Pîäîrênt \r 1 t; ......................................... _- 69.9. NZIÑYYOÃHG __________________________________________ __ 39 (average), 10 _ G d h ____________________________ __ 74.0 _ Iàlglijigëtitïnilchî_El-ö?._.í._l__.i ...... -_ - _ _ t . ._ ....... _. Dgfvçzciiâiiiicctii Example IV ._ . ____ __ . 0.5 . , . A resin-bonded backing is made up using curlated Sunila pulp beaten to a Schepper-Riegler freeness of , l 1 . . The following delamination resultsd are obtained when l5 Íäqut 8670rois Cdc’ using arid emeh long’ wddemer ger fllânâellt . disheet Containing i yion same proce'ure as escri e in comlgalred glflth a comparable Stan ar Example I in the following proportions to form a web no having approximately the same basis weight: yon ' Dclamlnation W t m~ eb con a ing __ it 20 v _Dm ouläcsespîlllcâmh Width 15% Nylon n 38.4. No Nylon 6 16 (average). c I t “eig , g. Dri’y Percent Sunila Pulp _______________ _. 0. 75 50 Nylon 6 ------------------- -- 0' 75 50 25 _ 'Ihe resulting sheet is bonded, impregnated with the same Delamination resistance is measured in‘this and in all of formulation `in the Same manner, dried and cured as in the following examples in accordance with the test method Example I in such a way that the percent impregnation defined by I, R. Dunlap in “Some Factors Affecting Ply is 14,5% with the following results; Adhesion in `Latex Saturated Papers,” appearing in Tappi, 30 Volume 40' No' 8’ August l19 57’ page 677“ Delamlnatlon, Gurley Tensile, 1b./in. Web eontaiuingoz./in. Stillness, of width Example Il mg./iii. A similar resin-bonded backing is made up using un . . beaten Duracel pulp of the type described hereinbefore 35 5o and Nylon 6 rods, of .the same type and Size as described N0 Nylon ------------ n 12.0 (averasel- 52 (ßvcrßsßl- 11.2 (avßrasel in Example I, using the same procedure as for Example I in the fOllOWÍUg PYOPQIÍ10I1§Í0 fOfm a Web having aPPTOXI- 1 ........... _%l\Iyou C 1d t Sigianlii’iiate. 23.5 ....... -_ 1 .0. 7 Gurley stiffness «is measured by a standard Gurley stiff maîely the Same baSlS Welghtf ness tester using the standard test procedure recom~ Dryy Weight, s. 40 mended by W. and L. E. Gurley, Troy, New York, and is expressed in milligrams per inch of width. Tensile Dry, Percent strength is measured by la standard tensile break test. Duracel Pulp _______________________________ __ 1.44 9G Nylon 6 Rods ............................... _- 0~ 06 4 Example V 45 _ , „ _ A resin-bonded backing is made up using curlated M _ _ ~ _ Sunila pulp beaten to a Schepper-Riegler freeness of the resulting sheet is bonded, impregnated with the same about 870 CC, and 1/16 inch, 60 denier per filament Nylon fofmulalloll lll the Same manner’ drled and, Cured as, m 6 rods and using the same procedure as described in Ex Example in such a way that the percent impregnation ample I Iln the following proportions to form a web '1S 72% Wllll the followlllg results: 50 having approximately the same basis weight: W _ _ Dela'mination 0b contammg* width Sunila Pulp _______________________________ __ Nylon 5 ----------------------------------- -- 4% Nylon 5 __________________________________________ __ 51.6, 37 (average). _ Drv Percent 1. 35 -l5 90 l0 The resulting sheet is bonded, impregnated with the 60 formulation used in Example I to four different percent ExampIe III y, Weight', g. 55 No N ylon 6 __________________________________________ _. . Dry ouiiccsesltlìrrlclîi’ch _ _l A. feslll'bollded bacllllg ls made ‘,lP l uslllg Cul al@ d ages of impregnation, and then dried and cured in the same manner as in Example I. That the resulting product Sllfllla Pulp beafenl Í0_ a SChOPPef-Rleglef ffeelless 0f possesses higher tensile strength and delamination resist about 870 CC- alld ¿l lllcll long’ l5 dellleÃPel lllanlellt ance and lower stiffness than a comparable standard sheet _Nylon 6 f0d5~llslllg the s_ame Procedure as lll EX‘ÈmPle I containing no Nylon 6 is illustrated in the graphs of ln lll@ followlllg Proportlçns t9 form a web llavlllg aP‘ 65 FIGS. 3, 4 and 5 for tensile strength, Gurley stiffness and proximately the same basis weight: delamination resistance, respectively, versus percent im pregnation based upon the weight of the unimpregnated Dry, Weìghhg. Dry, Percent sheet. Example V1 70 (iì’ulp ................................. _ y“ """""""""""""""""""""" " _ _ l S118 ‘ a _ Various handsheets are made up using curlated Sunila pulp 0f 870 cc. freeness and each of the bonding materials set forth in the second table below using the same proce The resulting sheet is bonded, impregnated with the same dure as in Example I. The bonding material in rod form formulation in the same manner, dried and cured as in 75 and the Sunila pulp are Vapplied in the following propor p 3,085,906 10. 9 _ tions to form a web having approximately the same basis unbeaten Duracel pulp containing 10.5% Nylon 6 rods. weight: The rods are 1/16 inch long and 15 denier per filament. The ñnished sheet weight (including the Nylon 6) is 30 pry, Weight, g. s Dry, Percent pounds per ream (l reain=480 sheets, 24 inches x 36 5 inches). The sheet is bonded by passing it twice between 1 P I un' a a IO-inch diameter pressure roller and a 4-foot diameter ___________________________ ..- ____ __ 1.275 Bonìîmglìfate?al ___________________________ __ . 85 .225 ' 15 _ heated drum at a speed of 25 feet per minute. The osur face temperature of the drum is approximately 450: F. _ A ëáß inch thick silicone rubber belt passing over the S'Iflhìrîgsuhtmzgoäheetsnïe bonded m a. Cârver Press £32.11? 10 pressure roller serves to equally -distribute the pressure the t S a at P0311 s pçr îguaäeblmcbnf’ressmêha a and prevent sticking to the pressure roll. Pressure is sup .me rârgiâïd ërîlsl tsh O‘fvn m1 tiìn af 165x :nmlv' I t ây arî plied at 60 pounds per square inch to two 6-inch diam labg tg45 t 7(1) e n‘ìrmfutîl . o e maan? gas ä epîlsll eter hydraulic cylinders at either end of the pressure rawusheet gveichîerîlì roe l îeânêlìlrdgc ed 'in eth Orsi e roller. The sheet makes contact with the heated drum manner” as fOrCEXâm la I îvlîth th follllâwino reselta'me 15 about three inches before going through the pressure Pe 1 e C’ u s' nip. In passing the sheet through the second time, the sheet is reversed so that the opposite side is in contact _ Leigh’ tiìpäirioei' $195133?? ägfengt, DI??? ° F. With the heated drum. The sheet is then impregnated oz./in with a latex impregnant of the following composition: 20 Polyethylene (Hyl'ax) __ DyIleL- 1A@ ‘ 1s 17 15 266 325 ' M6 15 365 69.2 64- 6 Control (no rods) ................................ __ 79.2 67- 2 57Í2 6810 46.5 30.5 Material Percent 25 Hycar OR 25 ________________ __ Example VII ' Handsheets are made up _ using curlated Sunila pulp B. F. Goodrich ___________ __ 70,0 Naugatex 2740.-. .- Naugatuck Chemical 0o-... 17. 5 Marmix _____ __ _ Marbond Chemical Co ____ __ 10.0 Durez 14798 _ Durez Plastics Co _________ ._ 2.0 _ . _ -_ Dow Chemical Co ________ __ 0.5 Versene _ _ _ _ . _ . _ _ . of 8170 cc. freeness and various bonding materials in granular form using the procedure of Example I in the 30 fOHOWlUg Proportion? t0 _form a Web having aPPl‘OXl- Water iS added t0 give 30% total solids. The impregnated sheet is dried and then cured for 60 mately the Same ‘03515 Welghtï seconds at 350° F. Physical properties of the impreg Dry, elg nated and cured sheet when determined as described in the foregoing examples are: Dry, W ‘ ht, . P g t . me“ . 35 Percent impregnation ________________________ __ 52 , ` i Solids Compo Supplier _________________________________ __ 1. 2’5 85 isslèllllldzinguiiïmeriai ___________________________ __ .213,5 i5 Delamination resistance _ _ ounces/inch ____________ __ 40 ’ . Tensile, pound/ inch of width __________________ __ 14 ' Elongation to break, percent __________________ _.. 4_ The resulting sheets are bonded in a Carver press for 10 40 The sheet is then kiiife-coated on one side with a nitro seconds at 200 pounds per square inch pressure at the cellulose solution to give a coating weight of 0.3 ounce temperatures shown in the table below. The particle size distribution is also shown in the following table. per square yard. On the opposite side itis reverse-roll coated with a 33% solids toluene solution of a pressure Percentage of Particles Bonding Larger Temp., than 13.8 ° F. 9.8-13.8 mils 7-9.8 mils 5.9-7 mils 4.1-5.9 2.9-4.1 mils mils mils Smaller than 2.9 mils Formvar 15/958 (polyvinyl for mai) _________________________ __ Etiiyi Cellulose N-ioo _________ ._ 365 300 17 19 25 20 18 10 6 5 10 3 4 i3 Butvar 55/ 98 (polyvinyl butyral) _ 374 65 14 10 3 1 2 5 Cellulose Acetate PM 203 ...... __ 437 21 29 19 7 6 6 12 The bonded sheets are impregnated with the impregnant fOrIIlUle 0f Example I t0 dePGSÍÍ beiWeeH abOUt 35 and 45% ‘0f impfegnanî based. 01‘1 the Welght 0f the dfY Sheet 20 30 sensitive adhesive of the following composition to pro vide a masking tape according to this invention which possesses greatly improved ñeXibility and conformability: and are dried and cured in the same manner as for Ex- 6o ample I, and delamination resistance is measured as de' b 'th the followin scribed a ove, wi GRS 1022 ________________________________ __ - percent. Imprßgnatwn _ iii A tt I 203 _ . _ 34.1 5’1 Aluminum hydrate C 730 ___________________ __ 20.3 Dáiìlilägâgân Piccolyte S115 ____________________________ __ 32.4 01111ce Per meh 65 m-Tolylene diisocyanate ____________________ __ Amberol M88 ___ 1115/195S.Ñ_.1bb--------------- _ t ‘ ‘ . gânltlrgisînocfoâsî ___________ __ .t. o 1 s compo“ lon’ Pergêns ----------------------- -----‘ g riuiïaises/ilsïîîìzüïl- S 1_d Pale crepe rubber results: ____ 1.0 4.1 âgâ Santovar A _______________________________ __ ggg 101101 ---------------------------------- --_-\- 0-8 . 25.8 70 . . . 0.8 . Example VIII The dried weight of adhesive is 2.28 ounces per square yard. 1 Example 1X i Rolls of pressure-sensitive tape are made using a resin-l bonded backing material. The paper for the backing is _The Peper 0f Example VH iS treated ín accordance Wlfh the method 0f Urllîed States Patent NO- 2,524,245> made on a l2-inch experimental paper machine using 75 to increase its elongation to break and delamination re 3,035,906 12 11 It is bonded by the same technique described and exemplified the manner in which it may be carried in Example VII and impregnated with the formulation described in Example I. The impregnated sheet is dried into practice, it will be readily apparent to those skilled in the art that innumerable variations, modifications, applications, and extensions of the basic principles in volved may be made without departing from its spirit and sistance. and then cured for 60 seconds at 350° F. Physical prop erties of the impregnated and cured sheet are as follows when measured in accordance with the foregoing ex scope. amples: The invention claimed is: l. A reinforced paper web comprising a continuous Percent impregnation ________________________ __ 51 network of moderately hydrated woodpulp fibers less than Delamination resistance, oz./in. _______________ __ 56 Tensile, pounds/inch _________________________ __ 12 Elongation, percent __________________________ __ 25 10 about 1A inch in length, said fibers being arranged in over lapping crossing relationship with one another so as to define a multiplicity of interstices between them, a multi Example X A resin-bonded backing is made up using curlated plicity of relatively large flexible and tough thermoplastic polymeric reinforcing members distributed substantially uniformly throughout the web in bonding relation with the woodpulp fibers, said reinforcing members being be Duracel pulp, beaten to a Schopper-Riegler freeness of 875 cc. and Nylon 6 rods of the size described in Example I, mixed in the following proportions to form a web hav ing approximately the same basis weight: Dry, Dry, Weight, g. Percent Curlated Duracel ______________ ._ Nylon 6 ________________________ _. 1. 35 0. 15 partially imbedded in said reinforcing members, and rub bery binder solids portions distributed substantially uni 90 10 A control backing is made containing no Nylon 6. The other sheets are impregnated with a solvent-base impreg nant of the following solids composition: Material Supplier Dry, Percent Depolymerized rubber (DPR) __ H. V. Hardman _________ -_ tween about 1 and 35 mils in cross dimension and at least about five times larger in cross-sectional area than said woodpulp fibers and defining a multiplicity of spaces 20 between said members, said woodpulp fibers being at least 3. 09 High Viscosity DPR ............... _-d 56.18 Amberol ST 137 .... ._ 25. 77 Staybelite Ester #l0__ Hercules Powder Co ____ _. 12. 89 Zirex ______ __ Newport Industries Ine.. _ 1. 03 Monsanto Chemical Co._- 0.52 Shell Chemical Co ...... __ 0. 52 formly throughout the web, said solids portions forming a multiplicity of bonds between the woodpulp fibers in 25 the individual spaces between the reinforcing members, the reinforcing members and the binder solids being pres ent in the web in amounts ranging between about 10 per cent binder solids and 50 percent reinforcing members and 70 percent binder solids and 2 percent reinforcing 30 members based upon the combined dry weight of the woodpulp fibers and the reinforcing members. 2. A reinforced paper web according to claim 1 where in said reinforcing members essentially comprise a long chain polymeric material. 35 3. A reinforced paper web according to claim 2 where in said polymeric material is nylon. 4. A reinforced paper web comprising a continuous network of moderately hydrated woodpulp fibers less than about 1A inch in length, said fibers being arranged in The impregnant solids is adjusted with toluene to give approximately 90% impregnation in both papers. The 40 overlapping crossing relationship with one another so as impregnated backings are dried and cured 5 minutes at 350° F. and are then tested for physical properties in multiplicity of fiexible and tough thermoplastic polymeric accordance with the foregoing examples to give the fol reinforcing members distributed substantially uniformly lowing results: throughout the web in bonding relation with the wood pulp fibers, said reinforcing members being at least about Percent Delamin- Stifîness, Impreg. ation, oz. ing/in. to define a multiplicity of interstices between them, a Tensile, 45 ten times larger in cross-sectional area than said wood l /in pulp fibers and defining a multiplicity of spaces between said members, said woodpulp fibers being at least partially imbedded in said reinforcing members, and rubbery binder solids portions distributed substantially uniformly 50 throughout the web, said solids portions forming a multi The manufacturers’ product names and trademarks plicity of bonds between the woodpulp fibers in the indi used herein shall identify the following substances and vidual spaces between the reinforcing members, the re types of materials. Hycar 1502X426 is a butadiene inforcing members and the binder solids being present in acrylonitrile copolymer comprising about 67% butadiene 10% Nylon 6 _____________ __ No Nylon 6 .............. _- 90. 5 90. 2 65. 6 38. 4 24 52 4. 0 3. 5 and 33% acrylonitrile and is in the form of a latex, while Hycar OR 25 is a more general name for the same type of material. Latex 2001 is a copolymer of butadiene and styrene in a 50:50 ratio. Naugatex 2740 is a similar co polymer of butadiene and styrene. Marmix is a copoly mer of butadiene and styrene with a high styrene content, say about 85 to 90 percent, while GRS 1022 is a buta diene-styrene copolymer with a low styrene content in the neighborhood of about 25%. Durez 14798 and Amberol ST 137 are heat setting phenol formaldehyde resins, and Amberol M 88 is a rosin modified phenol formaldehyde resin. Dynel refers to a high molecular weight copolymer of vinyl chloride and acrylonitrile with the latter being the web in amounts ranging between about l0 percent binder solids and 50 percent reinforcing members and 70 percent binder solids and 2 percent reinforcing members based upon the combined dry weight of the woodpulp fibers and the reinforcing members. 5. A reinforced paper web comprising a continuous 60 network of moderately hydrated woodpulp fibers less than about 1A inch in length, said fibers being between about 0.04 and 0.4 mil in thickness and between about 0.4 and 0.8 mil in width and being arranged in overlapping cross ing relationship with one another so as to define a multi plicity of interstices between them, a multiplicity of flex ible and tough thermoplastic polymeric reinforcing mem bers distributed substantially uniformly throughout the present in a relatively minor proportion. Versene is a web in bonding relation with the woodpulp fibers, said trade name for the sodium salt of ethylene diamine tetra acetic acid. Piccolyte S 115 is a polyterpene resin. 70 reinforcing members being between about l and 35 mils in cross dimension and at least about five times larger in Santovar A is an alkylated polyhydroxyphenol, while cross-sectional area than said woodpulp fibers and defin Ionol is a ditert-butyldiparacresol. Staybelite Ester #l0 ing a multiplicity of spaces between said members, said is a glycerol ester of hydrogenated rosin, and Zirex is a woodpulp fibers being at least partially imbedded in said zinc resinate. Having now described the invention in specific detail 75 reinforcing members, and rubbcry binder solids portions 3,085,906 13 14 distributed substantially uniformly throughout the web, about 1 and 35 mils in cross dimension and at least about five times larger in cross-sectional area than said wood said solids portions forming a multiplicity of bonds be tween the woodpulp fibers in the individual spaces be tween the reinforcing members. 6. A reinforced paper web comprising a continuous network of moderately hydrated woodpulp fibers less than about 1A inch in length, said ñbers being arranged in pulp fibers and defining a multiplicity of spaces between said members, said woodpulp fibers being at least partially imbedded in said reinforcing members, and rubbery lbinder solids portions distributed substantially uniformly throughout the web, said solids portions forming a multi-V plicity of bonds between the woodpulp iibers in the indi vidual spaces between the reinforcing members. multiplicity of rod-shaped thermoplastic polymeric re 10 9. A pressure-sensitive adhesive tape according to claim inforcing members distributed substantially uniformly 8 wherein said reinforcing members essentially comprise throughout the web in bonding relation with the wood a long-chain polymeric material. 10. A pressure-sensitive adhesive tape according to pulp fibers, said reinforcing members being between about 1 and 5 mils in cross dimension and at least about five claim 9 wherein said polymeric material is nylon. times larger in cross-sectional area than said woodpulp l1. A flexible, high delamination strength pressure fibers and defining a multiplicity of spaces between said sensitive adhesive tape which comprises a reinforced paper backing Web, and a pressure-sensitive adhesive layer on members, said woodpulp Íibers being at least partially imbedded in said reinforcing members, and rubbery one side of said web, said web comprising a continuous binder solids portions distributed substantially uniformly network of moderately hydrated woodpulp fibers less than throughout the web, said solids portions forming a multi 20 about 1A inch in length, said ñbers being arranged in plicity of bonds between the woodpulp iibers in the indi overlapping crossing relationship with one another so as vidual spaces between the reinforcing members. to define a multiplicity of interstices between them, a multiplicity of relatively large iiexible and tough thermo 7. A flexible, high delamination strength pressure sensitive adhesive tape which comprises a reinforced plastic polymeric reinforcing members distributed sub paper backing web, and a pressure-sensitive adhesive 25 stantially uniformly throughout the web in bonding rela layer on one side of said web, said web comprising a tion with the woodpulp fibers, said reinforcing members continuous network of moderately hydrated woodpulp being at least about iive times larger in cross-sectional ñbers less than about 1A inch in length, said fibers being area than said woodpulp iibers and defining a multiplicity arranged in overlapping crossing relationship with one of spaces between said members, said woodpulp fibers another so as to deiine a multiplicity of interstices be 30 being at least partially imbedded in said reinforcing mem tween them, a multiplicity of rod-shaped thermoplastic bers, and rubbery binder solids portions distributed sub polymeric reinforcing members distributed substantially stantially uniformly throughout the web, said solids por uniformly throughout the web in bonding relation with tions forming a multiplicity of bonds between the wood the woodpulp ñbers, said reinforcing members being be pulp fibers in the individual spaces between the reinforc tween about 1 and 5 mils in cross dimension and at least 35 ing members, the reinforcing members and the binder solids being present in the Web in amounts ranging be about five times larger in cross-sectional area than said overlapping crossing relationship with one another so as to define a multiplicity of interstices between them, a woodpulp iibers and defining a multiplicity of spaces be tween said members, said woodpulp `fibers being at least tween about 10 percent binder solids and 50 percent reinforcing members and 70 percent binder solids and 2 percent reinforcing members based upon the combined partially imbedded in said reinforcing members, and rub bery binder solids portions distributed substantially uni 40 dry weight of the woodpulp fibers and the reinforcing formly throughout the web, said solids portions forming members. a multiplicity of bonds between the woodpulp iibers in the individual spaces between the reinforcing members. 8. A flexible, high delamination strength pressure sensitive adhesive tape which comprises a reinforced paper backing web, and a pressure-sensitive adhesive layer References Cited in the file of this patent UNITED STATES PATENTS 1,848,732 2,880,112 Lfionne _______________ __ Mar. 8, 1932 Drclich _______________ __ Mal'. 31, y1959 in overlapping crossing relationship with one another so 572,962 Great Britain _________ _.. Oct. 31, 1945 as to define a multiplicity of interstices between them, a 708,622 Great Britain __________ __ May 5, 1954 on one side of said web, said web comprising a continu ous network of moderately hydrated woodpulp ‘fibers less than about 1A inch in length, said iibers being arranged multiplicity of iieXible and tough thermoplastic poly merio reinforcing members distributed substantially uni formly throughout the web in bonding relation with the woodpulp libers, said reinforcing members being between FOREIGN PATENTS OTHER REFERENCES Hoch: “Mechanics of Latex impregnation,” TAPPI, vol. 42, No. 3, March 1959, pages 164-465.