US2218351A - Method of making a matrix - Google Patents

Description

Oct, 15, 1940. Q B CROWELL 2,218,35T

METHOD OF MAKING A MATRIX Filed Aug. 1S. 1931 @y Figi, i5 v Fiqf,

Inventor.

Patented Oct. 15, 1940 v l t l UNITED {STA-'ras PATENToFFlc-E signor to*` Viceroy Manufacturing` Company Limited, Toronto, Ontario, Canada f Application Angine 1s, 1937, sei-'iai Norlzsasss '2 Claims; (Ci. 1r-25)y The invention relates to vthe production of I:In my prior Patent2,075,50'l. granted March printing plates by a moulding process and more 30th, 1937, I discloseda'method rand means for particularly to an improved method and means the -production of non-metallic printing `plates for making the matrix from a reinforcedplastic and the present invention is directed to improve- 5 capable of being moulded in impression-receiving ments therover which simplifythe process with- A5 contact with an original printing plate, type or out sacrificing thedesired accuracy; the like. f v In the above yreferred to patent thelplasticizing The principal objects of theinvention are to and moulding 'of -the matrix vmaterialwas carried reduce the cost and the amount of workl required out in one operation .while the entire plastic body in the moulded production of printing plates and was confined against spreading andrthe `plastic 10 to facilitate the formation of the printing plate was `,thus forced into al1 cavities and spaces-btm mould or matrix so that accurate printing plates tween the press heads and `a faithful mouldedA may be quickly and economically produced withreproduction depended on the plastic being forced out subjecting the original plates or type set Vup. to ll all of such cavities.V 1 It `frequently hap-rto damaging crushing pressure. i pened that incertain type kset ups a considerable. 1.5

The principal features of the invention reside body of plastic was required insorderfto :repro in the novel steps of forming the matrix byfirst duce a comparatively. simple vprinting surfacer and plasticizinga suitable plastic under pressure in after the moulding operationit was necessary to association withV a bonding element to form a cutlor grind away the excessive portions of thel reinforced base capable of receiving a moulded matrix. `'Ihe present, invention eliminates vthis 20 impression with the, minimum body distortion necessity by firstfincorporating a reinforcing ele and thereafter subjecting said reinforced base to: mentiduring theinitial and partial stage of vul` a second plasticizing operation invpressure.- en. canization, after which the partially vvulcanizred gagement with an original printing plate. type and reinforcedY sheet 4is subjected toffinalr andset up, or the like to permanently set said base Y complete vulcanization while receiving this 25 Withfthe desired impression therein so thatrubmoulded impression-about a printinglplate or ber printing plates may be moulded directly. the like with the minimum-displacementiof the therefrom. y matrix material. A

'In the drawing, i ,In Figures 11andf2 I have illustrated aplateni' Figure 1 is an elevational vpartxs'ection l view of presshaving a heated basey l. and heated head 2.- 30

a platen press illustrating one form of reinforced In producing the matrix forming sheetaccordmatrix forming base receiving its initial heat and ing toFigure 1, I place a sheet 3 Ofsuitable wire' Pressure treatment therein. screen on the base I and over this I arrange a Figure 2 is a view similar to Figure 1 illuStratsheet 4 of unvulcanized rubber (or other suitable Y ing a modified fOrm 0f matrix forming base unplastic material which may be advantageously 35 der initial treatment in the Platen press. employed) and pressure and heat are appliedso Figure 3 iS a Plan View partly broken aWaY that as the unvulcanized sheet 4 is plasticized it ShOWirlg the initially treated Plastic baSe removed will fill the various interstices in the wire screen from the DreSS- and permanently interlock therewith and form a 40 Figure 4 iS a perspective VieW 0f a portion 0f a. a. consolidated reinforced product ready for use 40 preheated base showing a modied form of in in the seeondstep of the process. terrlal reillfOrCemellt- The heat and pressure is maintained only suf- Figure 5 is an elevational view partly in seeyfioiently long enough to effect the partial vulcantion showing a portion of the preheated base ilization of the rubber sheet 4 and the permanent j luStrated in Figures 3 and 4 subjected t0 a Silb-y bonding thereof with the Wire screen and I find 45 sequent heet and pressure treatment in a platen that one-sixth to one-seventh of the normal full press in association with a metallic printing plate. vu1canizati0n is quite suitame, type Set up, 0r the like In the form of the invention illustrated in Fig- Figure 6 is an enlarged fragmentary View 0f ure 2 the wire screen is incorporated betweenv 5o Figure 5 Showing thematrix forming bese reeeivtwo rubber sheets 4 and 4' and vu1oanization is 5o ing its nal moulded Shapealso carried out only partially asindicated in' Figure 7 iS a VieW Similar t0 Figure 6 ShOWing connection with the product illustrated in Figthe original metal printing plate, or type set up ure 1. removed andthe final rubber printing plate be- In Figure 3 the partially vulcanized reinforced ing formed from the matrix. sheet is shown removed from the press after its 55 In Figures 5 and 6 the second and separatev step in'the method is illustrated showing the cut-out piece 5 placed in a vulcaiaingi'pressin association with a printing plate vt3 orother type set up which it is desired to reproduce,` which printing plate or other type `set upis shown with cavities 6 therethrough, and it will be` noted, particularly on reference to Figure `6,`i that `o nly sufficient pressure is placed on the press to imbed the raised `printing surfaces a slight-distance into the' body` of fthe part-vulcanized rmass fand that only avery limited local displacement of the adjacent faceof the 'mass' is brought about'v and thevpvlastic mass ldoes not flow into the cavities y6'."

This relation of the elements is maintained until-the vulcanization of the plastic forming body is completed after .which theplate l5 orother type set upis removed. AI rubber printing plate is-now formedsby placing a thin sheetnrof unvulcanized rubber 1 over. the. impressed surface ofthe matrix, the latter Vhaving-been pref-` erablyrst treated with a suitable parting sub# stance and by the application of heat and pres-v surev the rubber sheet is vulcanized to receive and-permanently retain -the impressions of the matrix-to provide an accurate printing surface. The presence of theinternal interlocking reinforcing elements will, by reason of its having been first bonded,` and consolidated with the or printingplate, thereby obtaining rubber ysheet during an initial step of vulcanizing, eiectively retain Vthe matrix from ho'ri zontal expansion and distortion underv theheat and pressure applied to vulcanize thevnal sheet the desired accuracy. in the nal product. i

While the present invention has been developed in connection with a matrix or rubber subjected 'to successive vulcanizing steps; the process may be carried out in connection with other plastics by rst subjecting the same to a pre-plasticizing temperature in associationiwithv the reinforcing agent to rst effect a definite bonding of the two elements after which the reinforced and partially treated plastic will be subjected to a final plasticizing and/or permanent setting operation in impression-receiving relation to a printing plate or other type set up.

The matrix. formed by `the above process may also be employed in the production of stereotypes or electrotypes as will be readily appreciated by those skilled in the art, in which case the steps indicated iny Figure 7 will not be required. As

shown-in Figure 5 or 6 no barriers are required to confine the matrix-forming body against horizontal 'fexpansiom `this step, as shown in my formerpatented process referred to, being eliminated, since inthe present case the entire matrixforming body isnot subjected to a uniform pressure .throughout and the reinforcing element is easily capable of c `confiningV the matrix bodily against the" very slight local expansionA force What I claim as'my invention is:

-13 YThe method of producinaa ubbe mtfix forprintingplates which comprises rrst firmly permanently' associating uncured rubber with a foraminousqreinforcing element under such con'- ditions of heatand pressure as to eliminate internal voids and only' partially vulcanize the rubber V'medium to substantially,one-sixth full vulcariization and render the composite product substantially incapable of `subsequent compression, and thereafter impressing the surface With printingcharacters and completing Ithe vulcanization of the rubber before removal of the said characters`- A.

2."Th'e method of producing aV rubber matrix for printing plates which comprises rstfirmlyv `permanently associating uncured rubber vwitha f oraminous reinforcing element 'under such conditions ofheat and pressure as to eliminate internal voids and only partially vulcanize the rubber'medium and render the composite product substantially 'incapable of subsequent compression, and thereafter `completing the' vulcanization in a second 'step While maintaining print'- yin`g"characters embeddedtherein onlya suf cient depth to effect local displacement of the rubber body While preventing contact of the rubber with-'the' depressedsurface areas of the printing characters.

` ORBY B. CROWELL.

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