US3101668A - Printing members and method of making same - Google Patents

Description

Aug. 27, 1963 H. R. LEEDS 3,

PRINTING MEMBERS AND METHOD OF MAKING SAME Filed March 14, 1960 INVENTOR fi l/FR) R. 15505 contains its own ink and does not bleed at its backing.

3-,l-0L668 Patented Aug. 27, 1963.

Un ed States Pat ()fi J 3,101,668 PRINTING MEMBERS AND METHOD OF MAKING SAME Harry Leeds, Racine,Wis., assignor toS. C. Johnson Son, Inc., Racine, Wis. Filed Mar. 14, 1960, Ser. No. 14,729

' 8 Claims. (Cl. 101401.1)

This invention relates to printing members and to methods for producing these members. More particularly, the invention relates to printing members having ink impervious backings, to printing members having the ability to produce multicolored imprints in a single step and to the method of making these printing members.

In the past, printing members containing their own supply of ink have had a tendency to bleed at the backing,

particularly when pressure is applied to the printing member .to produce an imprint: Bleeding at the backing of the printing member makes it diflicult tosecure the print mg member to supporting means such as hand stamp tinished object of the invention.

' berreferred to again in the following more detailed de-.

scription and examples. v

.In preparing the printing member having an ink impervious backing, a plastisol containing ink is placed in a negative mold, covered with a thermoplastic lilm and stocks, metal plates which may be inserted in mechanical equipment for repeated-use and the like. Many glues which have been used for fixing printing members carry-' mg their own supply of ink to supporting meanslare ad- I versely alfected by the ink causing deterioration of the bond between the printingmember and supporting means.

Further, it has not been possible to make printing members such as hand stamps or'other printing plates which are capable of producing imprints of multicolors in a one step operation. 3 Conventional hand stamps must be inked immediately prior to 'use.' This inking operation is accomplished by pressing the printing member of the stamp temperature sufiicientto gel the plastisol. Thisgelled' plastisol is a partially cured plastisol' which diifers from the initial plastisol in that it does not flow. Curing heated to a temperature sufficient to cause the formation of an ink-containing microporous resinbonded to the thermoplastic film. :Preferably, the plastisol, containing ink will be placedv in a negative mold and heated to a iseffected byv the coalescence of the resin particles at their} outer surfaces accompanied by the migration of all or a portion ofthe plasticizer into the resin. More extended curing results in a microporous structure of sub-v stantial strength; the pores being interconnecting and filled I with inkfl- After'the plastisolcontainingink is gelled, an-

ink impervious thermoplastic film is superimposed over 'an exposed portion of the gelled plastisol which contains upon an inked pad. The ink adsorbed by the printing member is then transferred to paper or other surface upon which it is-desired to make an imprint by striking" the paper with the-inked. member. Prior to the present invention, multicolored imprints could be produced in such manner by'inking a portion of a printing member with one color of ink *and subsequently inking the remaining portion with another color, both operations being accomplished prior to striking the surface upon which it is desired to. make the imprint. Perhaps also different portions of a printing plate could be inked with difierent colors by pressing the printing member against anink pad comprised of sections containing the desired colors, the sections being arranged to engage the" appropriate segments of the printing member. In the past, it also may have been possible to produce multicolored imprints by feeding different colored inks 'from a plurality of ink reservoirs through separate segments of a printing memher. In addition, it is well known that in'the production of multicolored lithographic Work, the several colors are accomplished by independent'printing steps. In such a I process, great care must be exercised to insure the proper registration of the sheets being printed, this being neces sary for the prevention of blurring of the colors at their lines of contact. All of these methods of producing multi colored print are cumbersome and expensive. The printing members and their supporting means are either complex or more than one step is necessary to use them. These difficulties arereadily overcome by the present invention.

ink and the -com'plete assembly again heated to form a unitary structure comprising a microporous microreticulated resin fille'd with ink bonded to an ink" impervious thermoplasticsheeting. In situations where printing members containing less flexibility are desired, there may be used inplace of the thermoplastic film a composite board comprising paper, card-board or other liber impreg na ted or coated with a thermoplastic resin. The resin coated or impregnated side of thecomposite board is bnouglitinto contact with the gelled plastisol and the ass'embly heated' to a microporous microreticulated inkbbiitaining resin" bonded to the composite board. As another desirable alternate, an-ink-free' plastisol-may be poured over the plastisol containing ink in a negative mold such ras those depicted in FIGURES 2 and 3. The two layers are then heated .to coalesce the two plastisols. The ink-freeplastisol becomes an inkimpervious thermoplastic layer bound to la microporous "resin which is fo rined'fromdhe 'plastisol containing ink. Preferably,

. the ink'containing plastisol will-be preheated to form the An object of the invention is a printing member which v Another object of the invention is a method of making a printing member containing its does not bleed at its backing.

Another object of theinventionis a printing member capable of producing a multicolored imprint in a single operation.

Still another object of the invention is a method of making a printing member containing ink of a plurality own inksupply which gel 'stage,*then covered with the ink-tree plastisol and again heated to form the composite structure. This procedure completely eliminates comingling of the two types ln' preparing printing members capable of producing multicolored imprints, the cavities of a multica'vity negative mold such as those showninFIGURES'Z and 3 are filled with a plastisol containing ink of the color desired for each segment of the final multicolor printing member, Each cavity of the multioavity mold is separated from the other cavities bybarriers. *These barriers make. I it possible to fill the cavities to a depth sufficient to cover the printing characters carried by the negative mold without comingling the colors. '7

. A suitable ink-tree backing which holds the variously colored segments of the multicolored printing member in a noncontiguous relationship to prevent comingling of the ink colors and smudging rat the lines'ot contact may 7 take rnany tforms. Asdiscussed earlier, the backing may consist of a sheet of inkimpervious thermoplastic resin,

will become apparent 'I hese drawings 3 a fiber board coated or impregnated with such a resin, or an ink-free plastisol which when heated becomes a thermoplastic or thermoset layer of resin; It also may consist of a liquid impervious cardboard, metal or any other material which is substantially ink impervious and which will maintain the color segments in a. noncontiguous rela- Itonshi-p. Regardless of the backing selected, the method of preparing the multicolored printing member may include the step of heating the negative mold filled with the plastisol which contains ink to gel the plastisol. This step is particularly helpful when an ink-free plastisol is used in making the backing. The use of a plastisol backing makes it unnecessary to have the lastisols containing different colored inks at the same level in the plurality of cavities of the negative mold prior to the application of the backing. When poured into the negative mold containing the plastisol containing ink, the ink-free. plastisol flows into the unfilled portions of the individual cavities bringing the level of the contents of those cavities to the top of the barriers separating the cavitiesif the contents are not already at this level. Additional plastisol provides the backing for the final product, joining its several color segments together. Thus, the printing surfaces of the individual segments of the finished multisegment printing member are precisely in the same plane, The preferred preheating step by'which the plastisol containing ink is 'gelle'd or semicured prevents corningling of the colors as subsequent steps of the process are carried out. This has colors expected. In some instances it is desirable to cover the filled mold with a plate or use other means to confine the contents during the final heating step. Such a plate,

it securely fixed over thetop of the filled mold, prevents undue expansion of the product during heating. It provides a means of regulating the porosity of the composition to some extent. A cover may also be used to retard the evaporation of some of the more volatile components of the plastisol. It providesa means tor bringing pressure, due to expansion of the plastisol containing ink, upon the plastic backing to enhance its ability to bond to the microporous resin formed from the plastisol containing ink. p

The word plastisol when used alone herein is intended to mean a conventional plastisol or organosol. Such plastisols are finely divided or colloidal dispersions of a synthetic resin or mixture of resins in a plasticizer or plasticizers with or without other materials such as stabilizers and the like. .When heated, the plasticizer and solvents penetrate the resin or volatilize andthe mixture sets by coalescence and subsequent solidification of the resin particles. Plastisols are conventionally used 2501 molding, casting films, coating or printing ,with the resin itself as a coloring agent or coloring carrying agent. The term ink containing plastisol as used herein means a special kind of plastisol. It is a plastisol which when heated will produce a microporous microreticu-lated resin-, ous structure, the pores of which contain a fluid carrying coloring matter. Its chemical composition may be considerably varied.1 Preferably, it is composed of a finely divided thermoplastic resin-or thermosetting resin in the thermoplastic stage of polymerization, a plasticizer for j the resin and a color carrying liquid which is a relative Mixtures of thermoplastic resins, plasticizers and non 4 solvents for the resins may be used. In addition, there may be used a combination of plasticizers, one or more of which has a greater solvency or plasticizing effect on the resin than the other. It will be appreciated that the terms solvents, plasticizers and non-solvents are relative terms. A liquid which may be a non-solvent for one resin may be a plasticizer for another. Although a liquid may act a partial plasticizer for a resin, it may still serve the function of a non-solvent in a resin-plasticizer-nonsolvent combination mentioned above. Thus, a resin and a plurality of plasticizers, one of which may be considered a primary plasticizer and one of the others a secondary plasticizer, may be used to prepare the ink contain ing plastiso of the invention. Similarly, it is possible to combine a resin and a plasticizer in combinations such that a portion of the plasticizer serves as a pl-asticizer and the remainder a nouasolvent as that'term is used herein. This resin-plasticizer combination is not-nearly as desirable as those discussed earlier, but is intended to he embraced by the present invention. A secondary plasticizer is a plasticizer which has limited compatibility with the resin. It usually dilutes the'primary or secondary plasticizer, thus reducing its ability to soften the resin. This is a valuable phenomena since it permits the use of many plasticizers whose compatibility with the resin would otherwise be excessive.

In the formation of the rnicroporous rnicroreticula-ted resin herein contemplated, the structure is formed by the partial coalescence of the resin particles. The resin particles become bonded at their surfaces fiormi-ng an innerconnecting network of microscopic pores which extend throughout the resinous structure and communicate with its surfiace. The non-solvent [for the resin and perhaps a portion of the plasticizer remains in the void-s between the partially coalesced resin particles, filling the pore network thus formed. Likewise, when an excess of plasticizer or a combination of primary and secondary plasticizers are employed beyond the maximum absorbable by the resin, this portion of the plasticizer or plasticizers does not penetrate the resin, but remains in the pore network to form, with coloring matter, the ink of the half-tone printing members of the present invention.

It will be appreciated that the softening points of many synthetic resins are lowered in the presence of various plasticizers, so that exact molding temperatures cannot be given, but will depend upon the particular mixture of plasticizer and resin. The time required will range from a few seconds to about one hour.

Any thermoplastic resin or thermosetting resin in the thermoplastic stage of polymerization may 'be used in the preparation of the ink containing plastisol. The synthetic resin will constitute a substantial portion of the composition, but as little as 15% of the composition may consist of resin. The maximum amount of ink which is consistent with a strong structure is desired. Usually, the resin content will vary from about 15 to about 65 percent by Weight of the ink containing pl astisol; about 20 to about 50 percent being preferred. (The resin powder methyl acrylate, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl butyral, polyvinyl acetate, copolymers of vinyl chloride and vinyl acetate, polyamides, such as poly e-caprolactam, polyhexamethy'lene adipamide, copolymers of adipic acid, sebacic acid, ecaprolactam and hexamethylene diarnine, polyisocyanates, otherwise known as polyurethane resins, such as the polyesters of 2,4-tolylene diisocyanate and polyethylene adipate, polyethylene, polypropylene, polyacrylonitrile, polyrnethylstyrene, alkyd resins, such as polymers of phthalic acid and ethylene glycol, polyesters of ethylene glycol and terephthalic acid, polyesters of ethylene glycol, terephthalic acid and acrylonitrile, thermoplastic epoxy resins, such as condensation products of epichlorohydrin and give some indication of nonsolvent liquids which can be employed in the, invention. M

1 LIST OF NONSOLVENTS polyhydroxy"compounds,. suchas =2, 2 bis-(4'-hydroiryphenybpropane. Polyvinyl ohloride and copolyrners or vinyl chloride and other ethylenically' unsaturated monomers are preferred. This list is not complete, and-those A u V III I I IPS I SI I I III n I I I IPI SII I W I P II C. M M H V III I I 1111 I m PI II T .II .I I I IP III II 1 .I I III II V. SIS S .1 PI I m P PI. II.II III .I.I. I .151 SII.I.I. .I I I I IPI I 5 j i .m m V. SII m I. "SST. S.. I.SI II II III I I. m IPI m II I I I I IPI IS n s 4 \|l w Pv r u n u u r W J u a 10... u n n u u I SI II I I I I S I I I I I. I mI I m .S II n P T F I I I .1 11 I I I II I I I .LPI I "a E S .n u n .P n m m S I II SI SII I. I 3 S81 S P II I I .1: I IPI IIJ a W a. C .III I 18 I I T. II II III I I I ISI III II I I I I IPI ISv A.. 8. II I I .IS I I I SI 11 II III .I I I IS III .II I I I I IPT. IS mm mm l .Ifi l l n ".W f z." .0 0 6. mw u v C\/ SC a 0 a 1. C. .OOWOC e D .TU S "am V216... $3 Ty afiwm ra ma mmzi h i hhh v. r x h r e 1 n l ahmno r 1 t ruh u 11 mwwm. c .wmmwm M ra armon m wm mw mm "m n m "mmmmhadmu name nwui nmw nmm mmhmmmmm lll at hm tmgb hezdee. n w. m rant H. eTPP w w nfl lats l aaa a .1ceen t l l1 nn i 0 .OPe i P. a s D m h. p mwmw 111m t da n. .he wy lyyweefl y Zu nflh. .P l /\h.w GGYSW ept S .l. yyy w l O O M ww h dO I m mIE tn t n r t lun e. t X l lH n m t t m mer ph yn m mha a & .mv a e bm SPLI ,ume H CY YO umO G Y en h t as e 0 1 d e s W 8 t0 t V. P B tZ yy 0V.V. CO0.le my .W O a 36 n0 a a hw .wuawmewma hm e nwmammmaanammwmnwwma maamm mmNmwemmmmmmm m n1? 5 Bar. B T 2 E1 12 DD TPPTI oocXnAr oLmv s M MPKN. w O 5 0 5 .O 5. 5 1 1 2 2 3 3 w. r aeYee A 6 I e H d e S n C h M a m. J. iC e .1 m m m m .V 00001 0 0 0 0 0.0 0 0 000000 000 0 mmmm m S S d i ,r e ,r C Y m m mm mm v 0 000 m 0 0 0 0 0 0 0 0 00PP0C I0 .P fi .m wm o Ucv c .x B y r V. a, h h ,fid,v 0100 0 I 0 0 G C C OCCOOP P00 0 m mi d I t. v. l e l m m mimwmfl m M 0 0 00.00 0 ;00 10001 P m wm w. 1 If w t a .r. mmmwmummmw m m 000m m m0 0 00 0 0 100003 3 mwfl m S u. n n mwmwmmh .S.I S a m wsm m m C, r1806 6 0 0.0.0 IP88. wwem t .1 i a .m a es Z 0 vlttv. w w U 00000 00000000000000 0 .m mm W Mem m B I a h o m C I ll A W e t h Vr w mummm m w A 0000 0 m 0 0 P 0 0 0 00000? 000 P m m m Pam a n .A t 1%. M e ld S mfim nma P 0 IP0I0 I I 0 0 P P 0 PC0011 111 1 m w mmm m i 6. hmmmmmwm n ulmiu ffn fTIIL. I me mmmm mw mu m wififl a Enemi s ra ma i m Z 1 .0 t t t S C yl methaerylate. 'ehloride.- polyvinyl chloride acetate;

pigments in: k type, car 1 Satisfactory es include methyl violen ictoria blue, victoria'green,

, calcazine'red, iosol redand nigrosine'blacks.

the'invention, the following examples are presented as specific embodiments only 3 and without intendingto limit the invention thereto.

A wire variety of coloring matter, may used includ ing "both dyes and pigments. Satisfactory elude"v the 'phthalocyanine blues and greens, in bon blacksand B-oxynaphthoic acid reds. y

azosol red Both fluorescent and phosphorescent dyes and'pigments long periods maybe used. 1 J

vents bove i base, (A )"lreparatzom of Multzcavzty-,Negatzve Mold will negative mold .for preparing a multicolored printing hydrocarbon distillates such as those boiling at a temperature of 300-450" F. v The plasticizer will usually be used in an in the range from about 40 to about the resin. I

Thisnonsolvent can be either volatile or nonvolatile. The more volatile the nonsolvent, the greater the pressure thatvlill have to be exerted to retain the solvent in the mixture untilthe structure has been formed. But since the final structure of the present invention is to Y contain an ink, it is desirable to use a nonvolatile liquid to avoid drying outof the structure during o fnonuse. v

fIhose skilled" in the art with the above fiacts will be able to select appropriate nons olvents. The nonsol useful for the various resins .which are disclosed a will be apparent to those skilled inthe art from t facts. However, the following listwhichis partial member such as that shown in FIGURE 4 was prepared as follows: A black and white painting of a bell with certain attending printed words was photographed. When developed by standard procedures,-the negative had black areas where the original photograph was white and conversely, where the original photograph was black the negative was transparent. The negative was superimposed over a zinc plate 5 which had been coated with a. solu areas of the coating 9, 10, and 11 which were covered by the opaque areas of the negative did not receive light and were not hardened. Subsequently, the metal plate was washed in methylalcohol removing the unhardened areas of the coating, leaving behind the hardened areas.

6, 7, and 8. The plate was then placed in an etching solution of nitric acid and left for a period of approximately 30 minutes. The now uncoated areas 9, 10, and 11 of the metal became etched by the nitric acid, reducing the metal plate to a relief. design of the original photograph image with the etched surfaces 9, 10, and Ill. duplicating the areas in the negative which were opaque to light, while the unetched areas 6, 7, and 8 duplicated the transparent areas of the negative. A groove 12 was machined around the perimeter of the zinc plate encompass- L ing the bell and accompanying words. Additional grooves 13 and 14 were machined, separating the bell from the words. Upon this master positive metal mold of FIG- URE 1, a Bakelite composition consisting of a phenol formaldehyde resin in the thermoplastic stage of polymerization on a paperbacking was impressed at an elevated temperature, about 400 F., to produce the three cavity negative mold of FIGURE 2. Upon heating alndthe application of pressure, the resin takes a position around the characters and design of the positive mold and once set it is not. afiected by subsequent heating.

It will be noted that the features of the mold of FIG- URE 2 are the reverse or negative of the master of positive mold of FIGURE 1. Barriers 15, 16, and 17 of FIGURE 2 correspond to grooves '12, 13,- and 1-4 of FIG- URE 1. These barriers establish color cavities 18, 19, and 20. 7

Either a thermoplastic or thermosetting resin in (the thermoplastic stage of polymerization may be used in the preparation of the negative mold in accordance with the If a thermoplastic resin is used, it

above procedure. should have a melting point in excess of that which is necessary in the heating step required to form the micro porous microreticulated ink containing resin of the print ing members. The positive mold as, well as the negative mold may be prepared in any manner known in the art. The method employed will depend upon'the equipment available and the nature of the multicolor printing member desired. The molds may even be carved by hand from wood, metal, rubber or the like. One very desirable alternate method of producing a positive mold is by stripping sections of the rubber facing from a commercially available composite rubber panel containing an embedded-fabric. The areas from which the rubber has been stripped serve as recesses corresponding to barriers of a negative mold which may be formed by pressing a thermoplastic. resin against it as discussed earlier. A negative mold may be. prepared with barriers such as those shown as 21,22, and23-in FIGURE 3. Barriers 22 and 23 are strips of metal, plastic, cardboard or similar material fitted into slots 24 and 25 of an outer bar-' hours at room temperature with the aid of aicatalyst to a tough, tear resistant rubber.

The term negative mold as used herein'means that the'features manifested onthe surface of the mold are in negative or reverse'relief as compared to the features of'the desired multicolor printing member and those of the positive or master mold from which the negative mold may be prepared in accordance with the method discussed in this example; I

. EXAMPLE 1 50 parts of polyvinyl chloride and 5 parts of tribasic lead sulfate, a stabilizer, were mixed with 50 parts of tricr esyl phosphate to form a paste. To this paste was added 5 parts of methyl violet together with 100 parts of ethyl hexanediol serving as a vehicle therefor. Similar ink containing plastisols were prepared using calcazine red and neolan black as the coloring agents. These inks was then placed in an oven and heated to a temperature of about 350 F. fora period'of 15 minutes. Thereafter the mold was removed from the oven, cooled, and the resultant multicolored printing member stripped from the mold. The printing member. carried the photograph and surrounding printing characters in line detail. There was no mingling of the colors during formation due .to the fact that each separate color containing plastisol wasv maintained in its own cavity of the multicavity mold during formation. Further, there was no mingling of the colorsafter the formation of the printing member because the printing members were maintained in a noncontiguous relationship by the backing which had become an integral part of the printing member during the heating step. Glue was placedon the back of the printing member comprising principally the polyvinyl chloride sheet which had become fused to the microporous microreticulated resin formed by the ink containing plastisols. The printin'g'member was then fixed to a conventional hand stamp stock. The printing member did not bleed at the backingwhen placed under pressure to exudeink from the pores of the printing and photographic indicia. It was used to make several thousand vivid imprints without reinking.

EXAMPLE-2 Example 1 was. repeated with comparable results, the steps of the process being the same except that the multicavity negative mold containing the different colored ink containing plastisols Was placed in an oven and heated to a temperature of approximately 250 F. for 8 minutes prior to the time the polyvinyl chloride backing was applied. After applying the backing, the mold was covered, replaced in the oven, and heated to a temperature of about 350 F. for an. additional 10 minutes. As inEx-ample 1, the final structure was a multicolor printing member consisting of a plurality of microporous microreticulated resin structures carrying ink of different colors, each being bonded in a noncontiguous relationship to "an ink impervious thermoplastic backing.

. EXAMPLE 3 Example 1 was repeated using in place of the thermoplastic film there specified, a fiber board which had been impregnated on one side with a polyvinyl chloridepolyvinyl acetate resin. The impregnated side of the fiber board was placed next to the plastisol. The printing member thus formed consisted of a microporous microreticulated resin bonded to a fiber board through an ink impervious plastic layer. Like the printing members of Examples 1 and 2, themulticolored inks contained in the multicolored printing member did not become comingled either during or after formation of the printing member.

' EXAMPLE 4.

Example 3 was repeated with comparable results by preheating the negative mold containing the plastisol conprising equal parts of polyvinylvchloride resin powder pffabout 200 mesh size and tric'resyl phosphate as a plasticizer therefor in place of the polyvinyl. chloride sheet.

The final structure was a multicolored printing member comprising a plurality of microp orous microreticulated resin segments with-the pores thereof filled with different colored inks bonded to an ink impervious backing formed by the coalesced ink-free plastisol. 4A multicolor printing member of this type can be seen .in FIGURE 4. Microporous resin segments 29, 3,0, and 31, each oontain inig a different colored ink is bonded in a noncontiguous relationship to the ink impervious backing 32f,

EXAMPLE e Example 5 was repeated, except that the mu-lticavity negative mold containing theink containing plastiso-ls was placed in an oven and heated to Ia temperature of approximately 200 F. for about minutes priorto the time that the ink-free plastisol was poured over the negative'mold. The mold was again placed in an oven and heated to a temperature of about 350 F. for minutes. The preheating step had the advantage of solidifying or gelling the plastisols containing ink prior to the time that I the ink-free plastisol was poured thereover. Thus, there was no diffusion of the ink in the plas'tisol containing ink into the p-lastisol comprising the backing as occurred to a limited degree in Example 5. I

(B) Preparation of Single Cavity Negative Mold A single cavity negative mold was prepared in a mamner identical to that of Example A (Erepanation of Multi; cavity Negative Mold) except that grooves 13 and 14 were omitted from the positive mold of FIGURE 1. The resulting negative mold was similar to that shown in FIG- URE 2 exceptthat it 'did not.possess thedividing barriers 16 and 17. f Y

. EXAMPLE 7 50 parts of polyvinyl chlOrideuIandQS of trihasic lead sulfate (a stabilizer) Wereinixed with 50 parts of dioctyl. phthalate to form a paste. To this paste was added 5 parts of methyl violet together with 100 parts of glycerol monoricinoleate, serving as a vehicle therefor. This ink containing plastisol was poured into a negative mold of Example B. A polyvinyl chloride film approximately '4 mills inthickness was laid over the ink containing plastisol in the negative mold. The mold was then closed'by placing an iron plate over. the top of the polyvinyl chloride sheet. The mold-was placed in an oven and heated to a temperature of about 35 0.. F. fora period of about 15 minutes. Thereafter the mold was removed from the oven, cooled, and the resultantprinting-member stripped from themold. Glue was placed on the back of the printing member, comprising principally the polyvinyl chloride sheet which had become fused to the micro porous microreticulated resin formed by the ink containing plastisol. The printing. member was then fixed to' a conventional hand stamp stock. In operation, the 'printing member made several thousand vivid prints. The printing member did not bleed at the backing when placed under pressure necessary to exude ink from the pores of the printing surface.

EXAMPLE Example 7 was repeated with comparable results except that the negative mold filled with the ink containing plastis-ol'was placed in an oven and heatedto a temperature of approximately 200 F. for 10 minutes prior to the time the polyvinyl chloride backing-Was applied. After applying the backing, the mold was covered, replaced in the oven and heated to a temperature of about 350 F.

- 10v I for an additional 10 minutes. Asin Example 7,'the final structure was a printing member consisting of a microporous microreticulatedresin bonded to an inkimpervious thermoplastic backing.

EXAMPL :9

I Example 7 was repeated using in plac efof the thermo; plastic film there specified, .a fiber board Whichhad been impregnated on one side withna polyvinyl chloridepolyvinyl acetate resin. The impregnated'side' of the fiber I board was placed next to. the plastisol. The printing member thus formedyconsis'ted of a microporous microreticul ated resin bonded to a fiberboard through an ink iin pervious plastic layer. I EXAMPLE 10 preheatingithe" negative mold containing the ink containing plastisol asindicated by Example'8. The advantage of the preheating step is that it provides a more firm composition, the partiallycur-ed ink containing plastis'ol, to

which to apply the backing. V

' EXAMPLE 1 1 Example wasrepeated, substitutinga plastisol comprising equal parts of polyvinyl chloride resin powder of about 200 mesh size and dioctyl ph thalate as a plasticizer therefor, in place of the polyvinyl .chloridesh eeting. The Y final structure was a printing member comprising a microporous microreticulated resin with the pores thereof filled withink bonded to an ink impervious backing formed by the, coalesced, pl'astisol. j g l g T EXAMPLE 12 Example 11 was repeated except that'the negative mold containing the ink containing plastisol was placed in anoven and heated to a temperature of approximately 200 F. for about 10 minutes prior to the time-that the ink-free plastisol was poured over it. Itwas again placed in an oven and heated to' a temperature of about 350 F. for i '15 minutes. The preheatingstephadtheadvantage of solidifying or gelling theink containingplastisol vprior'to the time the ink-free fluid plastisol was poured thereover.

Thus, there was no diifus'ionof theink in the ink contain I ing plastisolinto the plas-tisol comprising the-backing as occurred to a limited degree in Example 11.

a XAMrLn 1s A mold sirnilar to thatshown in FIGURE 3" with bar' riers 22 and 23 removed was filled with the inkcontaining plastisol of Example 7 and heated to a temperature of 340 F; for 20 minutes to form a microporous microreticulated resin containing ink. in the pores thereof. A type-cut stencil was cut and placed over the resin. A sheetof paper was pressed against this stencil and removed. The paper thus received a clear imprint of the type-cut upon the stencil, the ink having fed from the microporous resin thnoughthe stencil openings onto the paper,. I. I EXAMPLE 14: g

v The bottom of the three cavities of a mold similar to that shown in FIGURE 3 With-barriers 22 and 23 removed was covered to a'depth of about A: of an inch with an ink-free. plastisol consisting of equal parts of 2.00 mesh polyvinyl chloride and dioctyl phthalate. Bar riers 22 and 23 were put in place so that their bottom edge was slightly submerged in the ink-free plastisol. Three different color-ed ink containing plastisolsof the compositisol. The plastisols were coveredwith a metal plate and heatedto a temperature of 350, F."forj2 0 minutes, cooled,

and stripped from the mold; The molded" structure con-I sistedfof three non-contiguous microporous microre-ticulated resins each containing a' colored printing fluid ofa "color ditferentfrom the 'joth er twobonded to a nonporous ink-freetplastic backing. This'rnulticolored molded resin.

was mounted on a cylindrical drum of a conventional smooth face of the ink containing microporous resin there was fixed a type-cut stencil. The drum was rotated several hundred times, bringing clean sheets of paper into contact with the face of the resin. Each sheet received a clear imprint in three colors corresponding to the stencil type cuts.

The advantages of printing assemblies such as those disclosed in Examples 13 and 14 are manyfold. It is unnecessary to ink the pad, bringing many attending advantages. There is no ink leakage as there often is from the drum of the conventional mimeograph machine. Ink feed from the resin is more constant than from fibrous, felt or rubber pads normally used and fed bya viscous ink from the drumcavity. The drum or other device upon which the resin may be mounted may beleft in any position without fear of leakage. Most conventional duplicating devices must be left in a position so that the ink will not fiow from the ink well through the pad and stencil. The printing fluid is retained in the present microporous composition by cohesive forces due to. the resins system of extremely minute pores. The ink is emitted only when a porous article is brought in touch with it and upon the application of a slight pressure. 7

Now having generally'described the invention, what is claimed is: V

l. A method of making a printing member capable of producing a multicolored imprint in a single operation which comprises filling a' plurality of cavities of a multicavity negative mold, each cavity separated from the others by a barrier and carrying the desired printing charaoters in negative relief, with an ink containing plastisol to a depth whereby the exposed surface of the plastisol is substantially level with the upper portions of said barriers, the plurality of cavities containing a plurality of colors when filled, heating saidplastisol to a temperature sufficientto form a *gel, superimposing over said plastisol an ink impervious thermoplastic film and heating said plastisol and film to produce a microporous microreticulated resin containing an ink in the pores thereof bonded to said thermoplastic film. V

2. A method of making a printing member capable of producing a multicolored imprint in a single operation which comprises fillinga plurality of cavities of a multicavity moldyeach cavity separated from the other by a barrier and carrying the desired printing characters in negative relief, with a plastisol containing ink to a depth sulficient to cover the printing characters,,bu t of insufiicient depth to flow over the barriers separating the cavities, the plurality of cavities containing a plurality of colors when filled, heating said plastisol to a temperature sufficient to form a gel, placing an ink-free plastisol over an exposed portion of said gelled plastisol and heating said gelled plastisol and ink-free plastisol to produce a microporous microreticulated resin containing ink in the pores thereof bonded to an impervious layer of a coalesced resin.

3. A method of making a printing member capable of producing a multicolored imprint in a single operation which comprises preparing a positive mold of the desired printing member having'recess areas bounding segments of the mold which correspond to separate color areas of the desired printing member, forming a multicavity negative mold of the desired printing member having barriers bounding the cavities of the mold which correspond to separate color areas of the desired printing member by casting a thermosetting resin upon said positive mold, filling the cavities of said negative mold with an ink containing plastisol, the plurality of cavities containing a plurality of colors when filled, superimposing over an exposed portion of said plastisol an ink impervious thermoplastic film and heating said plastisol andfilm to i2 produce a microporous microretic-ulated resin containing ink in the. pores thereof bonded to said thermoplastic film. 4. A method of-making a printing member capable of producing a multicolored imprint in a single operation which comprises preparing a positive mold of the desired printing member having recessareas bounding the segments of the mold which correspond to the separate color areas of the desired printing member, forming a multicavitynegative mold having barriers bounding the cavities of the mold which correspond to separate color areas of the desired printing member by casting a thermosetting resin upon said positive mold, filling the cavities of said negative mold with an ink containing plastisol, the plurality of cavities containing a plurality of colors when filled, superimposing over an exposed portion of said plastisol an ink impervious thermoplastic film bonded on one side to a fibrous sheet, the thermoplastic side being next to the plastisol, and heating said plastisol and film to produce a microporous microreticulated resin containing ink in the poresthereof bonded to said thermoplastic film.

5. A method of making a printing member capable of producing a multicolored imprint in a single operation which comprises preparing a positive mold of the desired printing member having recess areas bounding the segments of the mold which correspond to the separate color areas of thedesired printing member, forming a mula ticavity negative mold of thedesired printing member having barriers bounding the cavities of the mold which correspond to separate color areas of the desired printing member by casting a thermosetting resin upon said positive mold, at last partially filling the cavities of said negative mold with an ink containing plastisol, the plurality of cavities containing a plurality of colors when filled, heating said ink containing plastisol to a temperature sufficient to form a gel, placing an ink-free plastisol over said gelled ink containing plastisol, and heating said gelled and ink-free plastisols to produce a microporous microreticulated resin containing ink in the pores thereof bonded to an impervious layer of coalesced resin.

6. A method of making a printing member capable of producing a multicolored imprint in a single operation which comprises preparing a positive mold of the desired printing member having recess areas bounding segments of the mold which correspond to separate color areas of the desired printing member, forming a multicavity negative mold of the desired printing member having barriers bounding the cavities of the mold which correspond to separate color areas of the desired printing member by casting a thermoplastic resin upon said positive mold, filling the cavities of said negative mold with an ink containing plastisol, the plurality of cavities containing a plurality of colors when filled, superimposing over an exposed portion of said plastisol an ink impervious thermoplastic film and heating said plastisol and thermoplastic film to produce a microporous microreticulated resin containing ink in the pores thereof bonded to said thermoplastic film, the melting point of said thermoplastic resin from which said negative mold is formed being higher than the temperature at which said ink containing plastisol and said thermoplastic film are heated to produce the microporous microreticulated resin bonded to the thermoplastic film.

7. A method of making a printing member capable of producing a multicolored imprint in a single operation which comprises preparing a positive mold, of the desired printing member having recess area's bounding the segments of the mold which correspond to the separate color areas of the desired printing member, forming a multicavity negative mold having barriers bounding the cavities of the mold which correspond to separate color areas of the desired printing member by casting a thermoplastic resin upon said positive mold, filling the cavities of said negative moldwith an ink containing'plastisol, the plu- 13 rality of cavities containing a plurality of colors when filled, superimposing over an exposed portion of said plastisol an ink impervious thermoplastic film bonded on one side to a fibrous sheet, the thermoplastic side being next to the plastisol, and heating said plastisol and thermoplastic film to produce a microporous microreticulated resin containing ink in the pores thereof bonded to said thermoplastic film, the melting point of said thermoplastic resin from which said negative mold is formed being higher than the temperature at which said ink containing plastisol and said thermoplastic film are heated to produce the 'microporous microreticulated resin bonded to the thermoplastic film.

8. A method of making a printing member capable of producing a multicolored imprint in a single operation which comprises preparing a positive mold of the desired printing member having recess areas bounding the segments of the mold which correspond to the separate color areas of the desired printing member, forming a multicavity negative mold of the desired printing member 113N- ing barriers bounding the cavities of the desired printing member by casting a thermoplastic resin upon said positive mold, at least partiallyfilling the cavities of said negative mold with an ink containing plastisol, the plurality of cavities containing a plurality of colors when filled, heating said ink containing plastisol to a temperature suflicientto form a gel, placing an ink-free plastisol over said gelled ink containing plastisol, and heating said gelled and ink-free plastisols to produce a microporous microreticulated resin containing ink in the pores thereof bonded to an imperivous layer of coalesced resin, the melting point of said thermoplastic resin from which said negative mold is formed being higher than the temperature at which said ink containing plastisol and said inkfree plastisol are heatedto gel the ink containing plastisol and to produce the microporous microreticulated resin bonded to the impervious layer of coalesced resin.

References Cited in the file of this patent UNITED STATES PATENTS 417,736 Meriman Dec. 24, 1889 2,318,465 Chollar May 4, 1943 2,427,765 Chollar Sept. 23, 1947 2,427,836 Chollar et a1 Sept. 23, 1947 2,558,269 Reilly June 26, 1951 2,777,824 Leeds Jan. 15, 1957 2,789,500 Reilly Apr. 23, 1957 2,819,668 McAneny Jan. 14, 1958 FOREIGN PATENTS 743,757 Great Britain Jan. 25, 1956

Claims (1)

1. A METHOD OF MAKING A PRINTING MEMBER CAPABLE OF PRODICING A MULTICOLORED IMPRINT IN A SINGLE OPERATION WHICH COMPRISES FILLING A PLURALITY OF CAVITIES OF A MULTICAVITY NEGATIVE MOLD, EACH CAVITY SEPARATED FROM THE OTHERS BY A BARRIER AND CARRYING THE DESIRED PRINTING CHARACTERS IN NEGATIVE RELIEF, WITH AN INK CONTAINING PLASTISOL TO A DEPTH WHEREBY THE EXPOSED SURFACE OF THE PLASTISOL IS SUBSTANTIALLY LEVEL WITH THE UPPER PORTIONS OF SAID BARRIERS, THE PLURALITY OF CAVITIES CONTAINING A PLURALITY OF COLORS WHEN FILLED, HEATING SAID PLASTISOL TO A TEMPERATURE SUFFICEINT TO FORM A GEL, SUPERIMPOSING OVER SAID PLASTISOL AN INK IMPERVIOUS THERMOPLASTIC FILM AND HEATING SAID PLASTISOL AND FILM TO PRODUCE A MICROPOROUS MICRORETICULATED RESIN CONTAINING AN INK IN THE PORES THEREOF BONDED TO SAID THERMOPLASTIC FILM.

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