CA1110531A - Method of continuously making a printing blanket construction - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method of continuously making a printing blanket construction is provided herein. The method includes the steps of supporting a fabric substrate web in coil form for unwinding rotation; unwinding and moving the forward portion of the substrate fabric web through a laminating station; and continuously laminating a polymeric layer adjacent the sub-strate web at the station. In this way, the polymeric layer may serve as a printing face. In this manner, the printing blanket constuction is manufac-tured in a minimum of manufacturing time, with optimum utilization of blanket construction materials and minimum scrap which can be recycled, with few auxiliary operations and minimum of air pollution.

Description

jr~ ~ ~
.
This invention relates to printing blankets and in particular to a method of making a printing blanket construction in a continuous manner or process.
Printlng blankets comprised of a plurality of laminated layers are well known and widely used tl-roughout the prlntlng industry; and, such bLanlcets are often used ln offset lithographic printlnp~ where the function oE SUCIl blankets is to transfer printing ink from associated printing plates to articles being printed.
~ Printing blankets of laminated construction produced by presently known techniques and ~ethods are generally comparatively expensive due to the comparatively large number of operations required in first forming the various blanket layers and then laminating such layers together to provide the desired bLanket characteristics. In particular, the processes or methods currently used in manufacturing or making such printing blankets require con-siderable manufacturing time; result in the generaticn of excessive scrap and particularly scrap which cannot be recycled; require numerous auxiliary operations such as mill processing, churning, drying, and the like; and create considerabLe air pollution due to the evaporation of solvents, ad-hesive means, and the like, employed in the lamination process.
It is a feature of one aspect of this invention to provide a sim-ple and economical method of making a printing blanket construction in a minimum of manufacturing time, with optimum utili2ation of blanket construc-tion materials and minimum scrap which can be recycled, with few auxiliary operations ~_. - 2 -. .
,:

':

5^3~L

of the character mentioned, and substantially without or with minimUln air pollution.
An ob~ect of another aspect of this invention is to provlde a method of making a printing blanket construction which is particularly adapted to have a printing face defined thereon continuously or, if desired, by conventional processes.
~ n object of yet another aspect of this invention is to provide a method of making a printing blanket construction wich is continuous and substantially uninterrupted.
By one broad aspect of this invention, a method is provided for continuously making a printing blanket construction comprising the steps of: supporting a fabric substrate web in coil form for unwinding rotation;
unwinding and moving a forward portion of the substrate web through a laminating station; continuously laminating a thermoplastic polymeric layer against the substrate web at the station; continuously bonding a reinforcing layer against the polymeric layer; and continuously calender-ing a printing face against the reinforcing layer.
By a variant thereof, the laminating and bonding steps are achieved simultaneously at the laminating station.
By another variant, the bonding step comprises: unwinding the reinforcing fabric from a web thereof supported in coil form for unwinding rotation adjacent the laminating station.
By still another variant, the laminating station is defined by a pair of pressure-applying rollers; and the method includes the step of extruding a controlled thickness of the polymeric material from an extru-sion apparatus having controlled outlet means therein ehrough which the polymeric material is extruded, and extruding the material against the substrate web to define a polymeric web.

. .

:. , 5.3~

In the accompanying drawings:
Figure 1 is a fragmentary schematic view primarily in elevation particularly illustrating one example of the method of continuously making a printing blanket construction in accordance with one aspect of this lnvention;
Figure 2 is a fragmentary cross-sectional v:lew taken essentially on llne 2-2 o~ Figure l;
Figure 2A is a view similar to Figure 2 showing a blanket con-struction made by the method of an aspect of this invention to highlight that such method may comprise simply continuously calendering a rubber face against a substrate;
Figure 3 is a fragmentary perspective view of a printing blanket construction made by the method of Figure l;
Figure 4 is a view similar to Figure 1 illustrating another example of the method of another aspect of this invention;
Figure 5 is a view similar to Figure 1 illustrating still another example of the method of still another aspect of this invention;
Figure 6 is a view similar to Figure 1 illustrating yet another example of the method of yet another aspect of this invention;

- 3 a , 5,~

FIG. 7 is a fragmentary perspective view of a blanket construc-tion which may be made by th~ method as presented in FIG. 4, 5 or 6;
FIG. 8 is a typical fragmentary cross-sectional view as taken on the line 8-8 of any one of FIGS. 4, 5 or 6 to illustrate a typical blanket construc~:ion. which is shown without a printing face having been l'orrne(l thereon;
F:[G. 9 is a vlew w:ith pnrts shown in cross section, parts in elevation, parts broken away, and parts shown schematically particularly illustrating the manner in which the blanket construction of FIG. 8 may have a printing facè defined thereon in a known conventional manner to complete the blanket construction so that it is substantially identical ;. ; .
: ', : ' ' to the blanket construction of FIG. 7; and FIG. 10 is a schema~ic view with parts in elevation and parts broken away particularly illustrating the manner in which the blanket con-struction of FIG. 8 may have a printing face defined thereon by calendering action en~ploying a so-called sklm unit to def:ine a blallket construction that :Ls substantially :Identical to the blanket construct:lon of FIG. 7.

5~3~L ~

. 1 DF.SCRIPTION OF ILLUSTRATED EMBODIMENTS
Reference is now made to FIG, 1 of the drawings which illustrates one excmplary embodiment of the method of this invention used in continuously making a printing blanket construction and such method is designated generally by the reference numeral 10. The method 10 comprises the steps of supporting a substrate web 11 in coil form on a suitable coil 12 thereof for unwinding rotation and in a ~anner which is well known in the art; and, a forward or leading end portion of the substrate web is then moved through what will ~ referred to as a laminating station 14 ~here a polymeric layer 15 is laminated against the sub-strate web in a manner to be described in more detail sub-sequently. A printing layer or face 16 is then formed ad-jacent the polymeric layer and in this example the printing face 16 is formed by uniting a rubber layer, also designated by the reference numeral 16, against the polymeric layer 15 to complete the printing blanket construction which is desig-nated by the letter B in FIGS. 1 and 3.
The polymeric layer 15 is laminated against the substrate web at the laminating station 14 employing a pair ~
of laminating or compression rollers 20 an upper one of which :~ -is a dual-purpose (calendering and compression) roller and :~
a lower one of which is disposed in supporting relation ~ ~;
beneath the substrate web 11. The upper one of the pair of rollers 20 at station ].4 serves as a calendering roller as mentioned and cooperates with a calendering roller 21 dis-posed thereabove to define the polymeric layer 15 at one ::
. circumferential position of the upper roller 20 as shown at 23. The lamination of the polymeric layer 15 is achieved .

''1' .' ' , . .

' '' ' ' '~' ~ . . .

lll{hS~

by laminating such layer with the upper roller 20 at a cir-cumferential position 24 which is diamstrically opposite the position 23.
The calendering roller, comprised of upper roller 20 S and roller 219 are provided with a suitable polymeric material as shown at 25 and the calendering of such material is achieved as is well known in the art to define the poly-meric layer lS, The blanket construction defined at the laminating station 14 is illustrated in FIG~ 2 and îs com-prised of the substrate web 11 and the polymeric layer 15 As mentioned above, a layer of polymeric materialpreferably in the form of rubber is formed adjacent the polymeric layer 15 to define the printing face 16~ In this example of the method of this invention, a layer or web 16 5 i5 provided in coil form as a coil 2~ thereof and suitably supported for unwinding rotation at a position downstream of the laminating station 14. The printing face or web 16 i5 united against the polymeric layer 15 downstream of the - laminating station 14 employing a pair of cooperating com-pression rollers each designated by the same reference numer-al 27~ After uniting the rubber layer or printing face 16 with the compression rollers 27 the resulting construction is in the form of the printing blanket construction B illustrated in FIG. 3 having a substrate web 11, polymeric layer 15, and rubber layer or printing face 16.
If desired, any adhesive means known in the art may be provided between the polymeric layer 15 and the rubber layer 16 to assure provision of a unitary laminated structure.
Also, it may be preferred to provide suitable internal means such as steam or electrical heaters, for example, for heating the compression rollers to a sufficient temperature which when actlng upon the seleated compatible polymeric materials uscd to d~fine the layers lS and 16 results in a high stroneth borld and unitary structure for -the completed blanket construction B.
I-t will also be appreciated that instead of uniting rubber layer 16 against the polymeric layer lS from a web of rubber 16 as shown in FIG. 1, the rubber layer or printing face 16 may be formed by applying a plurality of coats of uncured rubber against the polymeric layer 15 essentially in the manner presently employed in the art to define a printing face and then suitably curing the coats of rubber to complete such printing face 15. The web 16 of rubber material pro-vided as a coil 26 thereof may be a partially cured or sub~ `
stantially uncured web which may be laminated to layer 15 byrollers 27 or similar rollers and then such partially cured or uncured layer may be cured by passing same through a heated environment such as a heat tunnel, or the like, under controlled temperature and pressure conditions to complete the blanket B
in a continuous process. The completed blanket B may then be suitably wound on a take-up or supply roll thereof, A modification of the method of this invention -~
- comprises, in essence, defining a two-ply construction as shown in detail in the forward portion of FIG. 1 upstream of the section line 2-2 by calendering the polymeric layer 15 which may be in the form of a suitable rubber rompound as shown in FIG. 2A employing the pair of laminating compre~sion rollers 20 at the laminating station 14 as shown in FI~. lo The polymeric layer calendered at the station 14 is achieved in a continuous manner and defi.nes the completed blanket I' .' .
.

5~3 ~ ~

, . i, construction B of FI~. 2A without the need of applyin~ a polymeric matcrial or layer in the Eorm cf a printing face or layer 16 as shown in the downstream portion of FIG. l.
The above described techni~ue of ~alendering the polymeric layer in the form of rubber layer 15 in position i5 often referred to as a skim process and uncured or parti-ally cured rubber is placed in layer form on the substrate.
Cooperating rollers are often sold as a unit and referred to as a "skim unit" to provide this type of operation. Once the rubber layer is calendered in position it is cured by passing same through a suitable controlled temperature and pressure environment.
It will also be appreciated that the construction shown in FIG. 2 and comprised of substrate web ll and polymeric layer 15 made of plastic material may be the entire blanket construction B. In this ins-tance the plastic layer 15 is made of a material suitable for a printing face layer of a printing blanket construction.
Other examples of the method of this invention are illustrated in FIGS. 4, 5, and 6 of the drawing. The examples of the method illustrated in FIGS. 4, 5, and 6 are very similar to the example of FIG. l; therefore, such examples will be designated generally by the reference num-erals 10A, 10B, and 10C respectively and representative steps, associated apparatus, and components of the blanket construction being defined which are similar to correspond-ing items presented in FIG. 1 will be designated in the drawing .

by the same reference numerals as in FIG. 1 twhether or not such representative items are mentioned in the specification) ~ollowed by the associated letter designation A, B, or C
and not described again in detail~ Only those component items or steps which are different from corresponding ones illu5-trated in FIG. 1 will be designated by a new reference num-eral also followed by their associated letter designation and described in detail, The method 10A of FIG. 4 discloses the laminating 10 step which is comprised of the step of extruding a layer of -~
-polymeric material as shown at 30A to define a polymeric layer lSA against a substrate web llA tunwound from a coil 12A) employing a suitable extrusion apparatus 31A having controlled outlet means at 32A which produces a controlled lS thickness of polymeric material which defines polymeric layer 15A as a controlled thickness layer, The`method of 10A also comprises the step of bonding a reinforcing layer 33A
against the polymeric layer 15A at the laminating station 14A
employing a pair of cooperating compression or laminating 2Q rollers 20A, The reinforcing layer 33A is provided as a web in coil form on a coil 34A thereof and supported for unwinding r~tation adjacent the laminating station 14A. The lamination of the polymeric layer 15A against -the substrate web llA and the bonding of the reinforcing layer 33A against the polymeric layer 15A are achieved in a simultaneous manner at the laminating station 14A between the compression rollers 20A, also see FIG~ 8.
A layer of a suitable rubber defining printing face 16A may be suitably laminated against the top surface of the . reinfo~cing layer. 33A employing a pair of cooperating com-pression rollers 27A (which may be heated) in a similar manner ~0-- , `~

1~ 1 1}5~31 as disclosed in FIG. 1, The web or printing face 16A may be provided in coil form on a coil 26A thereof at a loca-tion downstream of the laminating station 14A, The method lOB of FIG, 5 discloses that the lam-S inating step is comprised of the step of disposing a pre-formed sheet l5B of polymeric material against a substrate layer or web llB (unwound from a coil 12B) to define the polymeric layer 15B and the sheet is provided in coil form or as a coil 36B thereof adjacent the laminating station 14B.
The method lOB comprises the step of bonding a reinforcing lay-er 33B against the polymeric layer or sheet lSB and the rein-forcing layer 33B is provided in coil form as a coil 34B
thereof adjacent the laminating station 14B. The lamination is achieved at the laminating station 14B by sandwiching the lS polymeric sheet or layer 15B between the substrate web llB
and the reinforcing layer 33B employing a pair of cooperating compression rollers 20B; and, the laminated construction thus defined is illustrated in FIG. 8 of the drawings. The lamina-tion of webs llB, lSB9 and 33B is achieved in a simultaneous manner at the la~inating station l~B~
. In the method lOB a layer of a suitable rubber material defining the printing face 16B may also be bonded or ~
suitably laminated against the top surface of the reinforcing : :
layer 33B employing a pair of cooperating compr~sion rollers 27B~ The printing face 16B may be defined employing a web of a suitable rubber material which is pro~ided in coil form and supported as a coil 26B thereof for unwinding rotation downstream of the laminating station 14B.
The method lOC illustrated in FIG~ 6 discloses a laminating step at a laminating station 14C and the laminating .

. . . ~ 1:`
.' ' ~

1~10531 step comprises providing a thickness of a suitable resin as indicated at 40C to define the polymeric layer 15C a~ainst the substrate web llC which is provided from a coil 12C
thereof. The step of providing the thickness of resin is indicated at 40C and is achieved by applying a volume of such resin as shown at 41C on the substrate web llC upstream of a doctor blade l~2C and controlling the horizontal position of such doctor blade in a manner that is well known in the art to provide a controlled thickness of the resin which ~ :
10 defines the polymeric layer 15C. :~ :
The method lOC also comprises bonding a reinforc-ing layer 33C against the polymeric layer 15C at the laminat-ing station 14C again employing a pair of cooperating com-pression rollers 20C; and, the reinforcing layer 33C is provided as a web and in coil form or as a coil 34C thereof which is supported for unwinding rotation adjacent the lamin-ating station 14C. In addition, the method lOC comprises the step of bonding a rubber layer or printing face 16C
- against the top surface of reinforcing layer 33C again employ-ing a pair of cooperating compression rollers 27C. The rubber layer 16C is provided in coil form as-a coil 25C
thereof.
j -The method steps disclosed in -the methods lOA, lOB, and lOC result in the provision of a printing blanket B as illustrated in FIG. 7 having a substrate web which is des-ignated by the reference numeral llA, llB, or llC; a poly-- ~ meric layer 15A, 15B, or 15C; a reinforcing layer 33A, 33B, or 33C; and a printing face of layer 16A, 16B, or 16C.
Similarly the intermediate blanket construction, prior to applying printing face thereon, is shown in FIG. 8 and is .

-l?-., ' ' , ' , ..

comprised o~ substrate web llA, llB, or ~lC; polymericlayer 15A, 15B, or 15C; and reinforcing laycr 33A, 33B, or 33C~ It will be appreciated that in the blanket construc-tion illustrated in each of FIGS. 7 and 8 the various layers S with the letter designation A are suitably laminated to de-finc the blanket construction ~ defined by the method lOA
of FIG~ 4, the various layers with the letter designation B
are suitably laminated to define the blanket construction B
defined by the method lOB of FIG. 5, and the various layers with the letter designation C are suitably laminated to de-fine the blanket construction B made by the method lOC of FIG. 6.
The printing face as defined by each of the methods lOA, 10~ and lOC need not nece~arily be made by laminating or uniting a thickness of rubber against a reinforcing layer utilizing suitable heated compression rollers, or the like~
For example, such compression rollers may be un-heated and if heating of the layer or web defining the printing face is required for bonding and/or curing purposes, such further heating may be achieved downstream of the com-pression rollers in accordance with any technique known in the art.
It-will also be appreciated that after defining a blanket construction as illustra-ted in FIG. 8 the rubber layer or printing face may be defined by conventional tech-niques. In particular, and as shown in FIG. 9, a blanket construction may be defined by suitably applying on a top reinforcing layer a plurality of thicknesses of rubber utilizing conventional or known techniques as illustrated by the block at 45. After the desired thickness of the ~: :
. .

:
.

i.3~ ~
... . ..

printing face is obtained which may be substantially the aame thickness as the thicXness of the printing face illus-trated in FIG. 7 the resulting construction may be passcd throu~h a suitable heat~d environment such as a heat tunnel ~6 and oured to complete a blanket construction B
which is substantially identical to the blanket construction B of FIG. 7.
The polymeric layer 15, 15A, 15B or 15C of each blanket construction B of this invention, regardless of the manner in which such layer is formed, may be any suitable polymeric material known in the art. One example of a mater-iàl which may be used for layers 15, 15A and 15B is a thermo-plastic rubber sold under the registered trademark TPP~ by the Uniroyal Chemical Division of Uniroyal Incorporated, EMIC Build-ing, Naugatuck, Conn. 06779. TPR tXermoplastic rubber is froma f~nily of polyolefin thermoplastic rubbers that combine fast manufacturing times of thermoplastics with the properties of a true rubber. ~P~ rubber of the type that may be used to define a printing blanket has a hardness as determined on the Shore Durometer, A scale, ranging between 65 and 95; and TPR
rubbers remain flexible and useable at temperatures ranging from minus 60 F. to plus 300 F.
The polymeric adhesive layer 15C disclosed in the method of 10C of FIG. 6 may also be made of any suitable ~5 polymer ~nown in the art and an example of a ma*erial in tha form of a thermosetting resin which has been used successfully is manufactured by DeSoto, Inc., Gulf Plastics Plant, 206 Culley Dr., JacXson, Mississippi 39206 under the trade de-signation LF~188. The LF-183 adhesive material is self-curing.
Because the LF 188 resin is self-curing the completed laminated construction has strength adequate for cutting, Eolding, etc.
~fter 48 hours and its full strength of bond i~ reached ~fter about seven days.
The polymeric layer 15C may also be a resin sold under lh~ tradc desi~nation Uvithane 782 by Thiokol Corp., Box 1296, Trenton, New Jersey 08607. This resin is prefer-ably cured by radiation immediately after itsapplication, -either as an exposed face layer or a sandwiched layer. An industrial 60" wide curing unit is available for radiation curing using an "electron beam" device and is sold by Energy Sciences Inc., Burlington Road, Bedford, Mass. 01730, under the trade designation Electrocurtain.
The polymeric layers 15A and 15B may also be made of a thermoplastic urethane polymer sold under the registered trademark of Q-Thane PH-56, by the K. J. Quinn ~ Co., Inc., 195 Canal Street, Malden, Mass. 02148. This material which was used successfully in laboratory trials has a Shore Duro-meter hardness ranging between 70 and 75 on the A scale and : when comparing it to the above-described TPR rubber provides higher bond strength than TPR and about the same handling and processing properties.
It may also be possible to use a thermosetting material ` for the layer 15 and this could be done by unwinding a film 15B and laminating such film between layers llB and 33B by curing such film using hot rollers 20B. The film layer 15B
may be 2-4 mils thick. A thermosetting film material of this character is sold by Daubert Chemical Co., 4700 So. Central Ave., Chicago, Ill. 60638.
The substrate webs 11, llA, llB, and llC and the reinforcing webs or layers 33A9 33B, and 33C may be made of ~::

any suitable material known in the art and preferably are made of fabric materials including woven, non-woven, and the like.
In the disclosure of the invention illustrated in FIGS. 1, l~, 5, and 6 of the drawings it will be seen that a layer of suitable uncured or partially cured rubber material defining the printing face is unwound from a web thereof which is provided in coil form and laminated in position.
~owever, it will be appreciated that the rubber face may be defined by calendering in position uncured or partially cured rubber and to highlight this point reference is made to FI~.
10 of the drawings which illustrates a plurality of cooperat-ing rollers 50, 51, and 52 referred to as a skim unit and such rollers may be used in defining the printing face of any of the blanket constructions B. For example, a suitable poly-meric material in the form of rubber may be provided as at 53 and calendered against the top surface of adjoining sup-porting layers whereby each of the blanket constructions B
~ay be comprised of a plurality of layers sas shown and with such layers being substantially identical to sùch layers as shown in FIG. 7. Once one or more uncured rubber layers are suitably calendered in position to define a printing face, such face is suitably cured to complete the blanket construction.
It will also be appreciated that in calendering a face layer on a blanket construction the calendering action may be achieved by applying a comparatively thick face in one pass or by applying a comparatively thin layersin a plurality of passes. Similarly, instead of bonding a single rubber face in position as shown in FIGS. 1, 4, 5, and 6, the rubber face may be defined by bonding together a plurality of successively applied layers.

' .. ' - ' .

`` ~

;3~ ~

The printing face comprising the blanket construc-tion has ~een shown in the drawings by cross-hatching as being made of rubber; and, it will be appreciated that any suitable rubber may be employed for this purpose. However, in some applications, A suitable polymeric material ;n the form of a synthetic plastic material may be employed to define the printing Eace.
In view of the above description, it will be seen that this invention provides a method of continuously making printing blanket constructions at considerable cost savings and wi-thout requiring specialized equipment.
While present examples of the method of this in-vention, and blanXet constructions made using same, have been illustrated and described, it will be recognized that this invention may be otherwise practiced within the scope of the following claims.

' ', '"'' '' I
T

Claims (4)

The embodiments of the invention in which an exclusive prop-erty or privilege is claimed are defined as follows:

1. A method of continuously making a printing blanket construc-tion comprising the steps of: supporting a fabric substrate web in coil form for unwinding rotation; unwinding and moving a forward portion of said substrate web through a laminating station; continuously laminating a thermoplastic polymeric layer against said substrate web at said station;
continuously bonding a reinforcing layer against said polymeric layer;
and continuously calendering a printing face against said reinforcing layer.

2. A method as set forth in claim 1 in which said laminating and bonding steps are achieved simultaneously at said laminating station.

3. A method as set forth in claim 2 in which said bonding step comprises: unwinding said reinforcing fabric from a web thereof supported in coil form for unwinding rotation adjacent said laminating station.

4. A method as set forth in claim 2 in which said laminating station is defined by a pair of pressure-applying rollers; and wherein said method includes the step of extruding a controlled thickness of said polymeric material from an extrusion apparatus having controlled outlet means therein through which said polymeric material is extruded, and extruding said material against said substrate web to define a polymeric web.