US3627255A

US3627255A - Unfilled flong

Info

Publication number: US3627255A
Application number: US863036A
Authority: US
Inventors: Chester J Daniels; Charles W Bennett
Original assignee: Rochester Institute of Technology
Current assignee: Rochester Institute of Technology
Priority date: 1969-09-30
Filing date: 1969-09-30
Publication date: 1971-12-14
Anticipated expiration: 1988-12-14

Abstract

A flong is formed of an unfilled, low-density, compressible base of cellulose fibers having open interstices between the fibers and a clay surface coating on one face. The surface coating meets the requirements for the working surface of a stereotype mat and prevents penetration of the relief printing form or molten stereotype type metal into the base material. The unfilled base is highly compressible and moldable in a drier than usual condition to reduce troublesome shrinkage.

Description

United States Patent Inventors Chester .1. Daniels Rochester, N.l Charles W. Bennett, deceased, late of Penfield, N.Y. by Lincoln Rochester Trust Company, executor, Rochester, NY.

App1.No. 863,036 Filed Sept. 30, 1969 Patented Dec. 14, 19711 Assignee The Rochester llnstitute 01 Technology Rochester, N.Y. by said Daniels UNFILLED FLONG 10 Claims, 4 Drawlng Figs.

US. Cl 249/134, 164/2. l0l/l7,249/117, 18/44 Int. Cl 329a: 1/02 Field 01 Search 164/2; 249/117, 134, 138; 162/181; 101/16, 17; 18/16 R, 4, 17 R 56] lllelerences Cited UNITED STATES PATENTS 1,108,667 8/1914 Bendixen 101/17 2,245,555 6/1941 Davenport. 101/17 2,831,224 4/1958 Libberton 164/2 Primary Examiner1-1. A. Kilby, Jr. AnomeyCumpston, Shaw & Stephens ABSTRACT: A flong is formed of an unfilled, low-density, compressible base of cellulose fibers having open interstices between the fibers and a clay surface coating on one face. The surface coating meets the requirements for the working surface of a stereotype mat and prevents penetration of the relief printing form or molten stereotype type metal into the base material. The unfilled base is highly compressible and moldable in a drier than usual condition to reduce troublesome shrinkage.

INVENTION- WET 72% MOISTURE BY WEIGHT DRY 5-0 MOISTURE BY WEIGHT PRIOR ART- WET 20-4 MOISTURE BY WEIGHT DRY 6.25% MOISTURE BY WEIGHT ESTIMATED sTREss/ LBS/ IN? A INVENTION COMPRESSIVE STRAlN-fiI-x/OO IATENTEDIIECMIQYI 3,627,255

SHEEI I [If 3 nvvmndm- WET 7.2 MOISTURE 0v WEIGHT DRY 5.0 MOISTURE BY WEIGHT PRIOR ART- WET 20- 4% MOISTURE BY WEIGHT DRY 6.25% MOISTURE BY WEIGHT PRIOR ART I -INVENTION N 10,000

g l 9,000 3 I I 1115? llhwsr 0,000 9+: 7/ DRY \f g 7,000 m 17, 0,000 a I 1/ 5,000 E I 4,000 a IO 20 3O 4O 5O 6O 7O 8O 90 I00 COMPRESSIVE STRAIN A x 100 CHARLES W BENNETT CHESTER J- DANIELS Fjfi [y INVENTORS AT TORNE YS I MTENTED M61419?! SHEET 2 [IF 3 INVENTION- WET 7.2% MOISTURE BY WEIGHT- DRY 6.38% MOISTURE BY WEIGHT N m T m V W T E 7 w I /kl Y R v D vl/fl E WA D O o 0 O o 0 o O O O 0 now w m. w w, m w m w. p m M P m H 8 6 5 4 3 2 2 mmim Tmmfiw QMEECE DANIELS S m T N E V m COMPRESSIVE STRAIN x100 CHALES'W BENNETT CHESTER J- ATTORNEYS PATENTED 05m 41s?! 3527', 255

sum 3 [1F 3 CHARLES W- BENNETT CHESTER J- DANIELS INVENTORS ATTORNEYS UNFIILLED FLONG BACKGROUND OF THE INVENTION I-"longs for making stereotype mats are well known and widely used, and they have been evolving toward sufiicient compressibility to produce a flat-backed stereotype mat that does not need backpacking. Other requirements for strength, heat-resistance, flexibility, an accurate impression, etc., have made the structure of flongs a complex balancing of characteristics.

Commercially available flongs have generally had cellulose fiber bodies filled with clay, diatomaceous earth, and other such materials. The desired compressibility was obtained with moist plasticity requiring a minimum premolding moisture content of, for example, -50 percent by weight, and the materials of the flong base flowed or shifted with such moist plasticity when the flong was pressed against the relief printing form to make a mold for casting a stereotype plate. The filling materials made such flongs relatively dense and closely packed with no open interstices between the cellulose fibers.

This assured that molten metal or plastic for the stereotype plate casting would not penetrate into the mat and prevent its release from the cast plate. The fillers also affected the moist plasticity of the flong, and much of the prior structured design has been devoted to careful choice of filler materials for flongs. The only fiongs widely used today are such filled flongs using moist plasticity for their moldability and represented generally by U.S. Pats. Nos. 2,739,068; 2,825,645; 2,918,399; and-3,061,897.

The relatively moist prior art flongs molded under moist plasticity suffer substantial shrinkage when the molded mat is scorched or dried before casting the stereotype plate. Such shrinkage has been presented as an advantage in reducing the size of the stereotype plate and the amount of paper required to print a newspaper page from such plate. However, such shrinkage presents a substantial problem of register of the different color impressions of the color printing that is becoming more common in newspapers. Any shrinkage must be very accurately controlled to accomplish this, and for several practical reasons this has been difficult. For example, flongs are shipped in moistureproof containers but unavoidably lose moisture to the ambient atmosphere as they are stored, unpacked, and handled. Also, the ambient atmosphere varies substantially between warm, humid, summer days and the dry, heated interiors of buildings in the wintertime. Hence it is very difficult to control the premolding moisture content of a flong, and the shrinkage of prior art flongs have been relatively sensitive to changes in moisture content.

THE INVENTIVE IMPROVEMENT Any improved flong must meet required characteristics such as: capacity to withstand operating stress, wear, and temperatures up to 700 F.; easy release from the relief printing form and the cast stereotype plate; durability and flexibility; capacity to mold an accurate and smooth impression of the printing form; and sufiicient compressibility to result in a flatbacked mat that does not require backpacking. The inventive flong equals the prior art in all these conditions and improves on many of them. At the same time the inventive flong is usable in a drier state that results in less shrinkage and fewer registration problems, particularly in color printing. The inventive flong is also more compressible, usable under drier conditions, is less sensitive to moisture changes in the ambient atmosphere, and requires less care and handling to ensure a particular moisture content. The result is a flong that is easier to use, saves on labor, and requires less skill to prepare better stereotype plates that print better and are easier to use.

.I SUMMARY OF THE INVENTION These advances are accomplished according to the invention by a departure from the age-old concept of a clayfilled cellulose fiber base, and the inventive flong uses an unfilled base with substantial open interstices between the fibers. The

prior art has been so engrossed in the characteristics and refinements of various fillers that the possibility of an unfilled flong has been overlooked. Also. the working face of the inventive flong has a surface coating that meets the requirements for stereotype mats. The result is a base that is highly compressible at moisture levels well below the operating ranges of filled flongs so that it shrinks very little, and yet has a tough, smooth surface that makes an accurate and exact mold of the relief printing form and produces a polished and accurate plate faithfully copying the printing form.

The unfilled base is preferably formed of cellulose fibers arranged with open interstices between the fibers so that the base has a Iow-density and is highly compressible. The surface coating is bonded securely to the base without penetrating it, is stable and resistant to molding and casting temperatures, is sufficiently plastic to conform accurately to the relief printing form, is porous to air and nonporous to the plate casting material, resists penetration by the relief printing form, and is readily releasable from the relief form and from the stereotype plate. Preferably an internal sizing is used in the fiber base in amounts that do not substantially reduce the open interstices between the fibers.

THE DRAWINGS DETAILED DESCRIPTION The inventive flong has a body of base 10 of cellulose fiber material preferably formed of suitable paper-making materials such as wood pulp fibers or refined cellulose material. The fibers are formed together without compression so that the base has a low density of less than 0.020 pound per cubic inch and preferably from 0.0] to 0.01335 pound per cubic inch with a preferred thickness of about 0.060 inch. This contrasts with prior art filled flong densities ranging around 0.03 pound per cubic inch. The cellulose fibers of base 10 are arranged with substantial intersticial spaces that are left open to make the base highly compressible and porous to air. The fiber materials of base 10 are selected from generally known materials for adequate strength and flexibility for known flong uses.

The inventive unfilled and open intersticial flong body is highly compressible under moderate pressures that eliminate the intersticial spaces, and it is much less dependent on the flow of material with moist plasticity than filled flongs. This will be explained in more detail below in considering FIGS. 1 and 2. Generally, however, the inventive flong body preferably contains less than 10 percent moisture by weight in premolding condition. For example, successful matmaking with the inventive flong can be accomplished with moisture content from 5 percent to 8.2 percent by weight as shown in the graphs of FIGS. 1 and 2, and in ordinary newspaper work the inventive flong is readily compressed from 0.060 inch down to 0.020 inch.

Such high compressibility of body ll0 results in a relatively deeply incised stereotype plate in which nonprinting recesses or depressions extend relatively deeply between the printing surfaces. In molding the flong into a stereotype mat the relief surfaces press deeply into the flong efiecting a substantial compression, and the incised or recessed areas around the relief surfaces leave the flong relatively uncompressed for a sharp contrast resulting in a deeply incised plate molded from the mat. Such a plate is easier to work with and is a desirable result of the enhanced compressibility of the inventive flong.

For a stifier flong body, an internal sizing is preferably used to bond the cellulose fibers more rigidly together without substantially filling the intersticial spaces. A preferred internal sizing material is starch, although other sizing materials are available. Preferably, sizing material is used only up to percent by weight of; the base.

The working surface of the inventive flong is made smooth and tough for use as a stereotype mat by a surface coating 11 that meets several requirements. Coating ll adheres well to the body of the flong, is free of surface defects and voids such as caused by air bubbles, and does not penetrate deeply into the body of the flong to reduce its compressibility. Coating 11 is preferably thin, tough, and plastic enough to conform readily to the relief printing form against which it is pressed as the body of the flong is compressed. Surface coating 11 is also sta ble and resistant to the 600 F., to 700 F., temperatures of molten-type metal or plastic; it is porous to air and nonporous to the plate casting material; it also resists cracks, breaks, and penetration by either the elements of the relief printing form or the stereotype casting. In addition, the surface coating is readily releasable from both the relief printing form and the stereotype plate.

Surface coatings having the required characteristics include clay coatings having adhesive binders, plasticizers and release agents. The following is one preferred coating formula that meets the above characteristics and works well on the inventive flong.

The above example of a workable coating mix has an adhesive-to-pigment ratio of 12.5:100 and renders 45.6 to 50.8 solids depending on the evaporation of the methanol. Though other adhesives may be used in the coating mix, polyacrylamide has performed particularly well in resisting decomposition under the rigors of stereotype casting operations.

The coating can be applied with standard coating equipment, and it is preferably formed as a wet laydown of approximately 0.0025 inch to set up as a dry coating of0.00l 5 inch.

Additional smoothness for the inventive coating to give a polished effect to the cast stereotype plate is achieved by burnishing the coating preferably before it has completely dried or set. This preferably done with a high-speed brush of horsehair or similar material to result in a burnished set or brush-burnished set when the coating hardens or sets after such burnishing. The burnishing appears to remove unevenness, smooth out the coating and give it a high gloss as it sets. The burnished set effect is much like calendering or super- In use, base 10 is formed and coating 11 is spread over base 10 and preferably burnished with a high-speed brush to form a brush burnished set. After coating ll has completely set with its burnished smoothness, it is ready for molding into a stereotype mat. This is done by compressing the flong against a relief printing form to press the relief surfaces of the form against coating 11 and force them deeply into the flong. The resulting molded mat is schematically illustrated in FIG. 4.

The mat is scorched, and the printing plate is then cast. by pouring plate casting material over the molded surface of coating 11. Such plate casting material is normally moltentype metal, but can be molten plastic. The air porosity of coating 11 and base 10 allows air to be drawn from the surface of coating 11 through the mat to prevent any air bubbles in the plate. Since coating 11 is nonporous to the molten plate material, however, such material does not penetrate coating 11 or base 10, and it conforms to the surface of coating 11 to form a plate that accurately reproduces the printing form.

The compressibility of the inventive, low-density flong body relative to the prior art filledflongs that required flow of material under moist plasticity is well shown in the graphs of FIGS. 1 and 2. These graphs plot the percent compressive strain of a fiong (At/TXlOO) or the change in thickness produced by compression relative to the original thickness, expressed as a percentage, with the estimated stress PM in pounds-per-square-inch. The estimated stress figures were obtained from a dial indication of the total force applied by a press compressing a flong against a relief printing form and a calculation of the compression area of the flong. The prior art and the inventive flongs were each tested by the same calculated estimation and with the same force indicator so that any errors in the estimation are equally reflected in each plot. The prior art flongs graphed in FIGS. 1 and 2 are the two most popular flongs commercially available at present and practically no other flongs are now in use.

FIG. 1 shows that one common, prior art, filled flong achieves a compressive strain approaching 50 percent only at high pressures, and only when relatively wet with a 20.4 percent moisture by weight. In drier condition with 6.25 percent moisture by weight, the compressive stress rose more sharply for each increment of compressive strain, particularly at low pressures. The filled flong of FIG. 1 never achieves the compressibility capacity of even the driest sample of the inventive flong, and when the filled flong is well moistened to enhance its compressibility, it will suffer severe shrinkage.

The filled, prior art flong of FIG. 2 is also commercially available and improves on the prior art flong of FIG. 1 in both wet and dry condition. However, it does not equal the compressive capacity of the inventive flong, whose curves are reproduced in Fig. 2 for comparison. Also, the filled flong requires considerably more moisture for reasonable compressibility, particularly at low-pressure stress.

One of the effects of such enhanced compressibility is shown in FIG. 4. The back 12 of the molded mat is flat, and all the printing surfaces, including both letter surfaces 13 and halftone surfaces 14, lie on a plane 15 spaced from back 12 by the distance d. Uncompressed areas of the mat between printing surfaces 13 and 14 rise to various heights above the printing surface plane 15 to form a relatively deeply incised plate.

The compressibility of prior art fiongs was insufficient to compress the relative large regions of halftones as deeply into the mat as the smaller printing areas, and halftones were correspondingly low or below the general plane of the printing surface for the stereotype plate. In printing from such a plate the paper had to be forced beyond the normal printing plane inward into contact with the halftone areas. The highly compressible, inventive flong avoids this problem by allowing the calendering, yet it is accomplished with light pressure and halftone areas to be compressed to the same depth in the mat without loss of body compressibility.

Although the preferred coating detailed above has been found very satisfactory for use on the inventive flong, other similar and related coatings can be devised to be equally successful. Some of these have already been compounded.

as other printing areas so the entire printing surface of the molded plate is in one plane 15. I

Thus, the invention accomplishes its objects in a highly compressible and relatively dry flong with a surface coating making it a successful stereotype mat. lt shrinks very little for excellent control of color printing, and it provides a highquality, polished stereotype plate that is relatively deeply incised for easy printing. The flong is also durable and usable in all present working situations, and meets all the practical demands placed on a flong.

Persons wishing to practice the invention should remember that other embodiments and variations can be adapted to particular circumstances. Even though one point of view is necessarily chosen in describing and claiming the invention, this should not inhibit broader or related applications within the spirit of the invention. For example, a variety of cellulose fiber and sizing materials can be used in the base, and the coating material can be varied within the scope of the requirements for the invention.

We claim:

1. A flong comprising:

a. an unfilled, compressible base of cellulose fibers arranged with a substantial volume of open interstices between said fibers;

b. said base having a density of less than 0.020 pound per cubic inch;

c. a smooth, surface coating on a face of said base;

d. said surface coating including a binder securing said coating to said base without substantial penetration of said base;

e. said surface coating being stable and resistant to temperatures as high as 700 F;

said surface coating being sufficiently plastic to conform to a relief printing form under flong compression pressures;

g. said surface coating resisting penetration by elements of said relief printing form under said compression;

(ill

h. said surface coating being readily releasable from said relief form and from a stereotype plate cast against said surface coating;

i. said surface coating and said base being porous to air; and

j. said surface coating being nonporous to the casting material for said stereotype plate.

2. The flong of claim 1 wherein said base includes an internal sizing material leaving a substantial volume of said interstices.

3. The flong of claim 2 wherein said internal sizing material comprises starch up to 15 percent by weight of said base.

4. The flong of claim 1 wherein said surface coating comprises a clay coating and said binder comprises polyacrylamide.

5. The flong of claim ll wherein the premolding moisture content of said base is less than 10 percent moisture by weight.

6. The flong of claim 1 wherein said surface coating has a burnished set.

7. The flong of claim ll wherein said surface coating has a brush-burnished set.

8. The flong of claim ll wherein said cellulose fibers comprise 75-95 percent by weight of said base, said base includes an internal 'sizingof starch 0-15 percent by weight of said base, and the premolding moisture content of said base is 5-20 percent moisture by weight of said base.

9. The flong of claim 8 wherein said surface coating comprises a clay coating and said binder comprises polyacrylamide.

10. The flong of claim 9 wherein said surface coating has a burnished set.

Claims

1. A flong comprising: a. an unfilled, compressible base of cellulose fibers arranged with a substantial volume of open interstices between said fibers; b. said base having a density of less than 0.020 pound per cubic inch; c. a smooth, surface coating on a face of said base; d. said surface coating including a binder securing said coating to said base without substantial penetration of said base; e. said surface coating being stable and resistant to temperatures as high as 700* F.; f. said surface coating being sufficiently plastic to conform to a relief printing form under flong compression pressures; g. said surface coating resisting penetration by elements of said relief printing form under said compression; h. said surface coating being readily releasable from said relief form and from a stereotype plate cast against said surface coating; i. said surface coating and said base being porous to air; and j. said surface coating being nonporous to the casting material for said stereotype plate.

5. The flong of claim 1 wherein the premolding moisture content of said base is less than 10 percent moisture by weight.

6. The flong of claim 1 wherein said surface coating has a burnished set.

7. The flong of claim 1 wherein said surface coating has a brush-burnished set.

8. The flong Of claim 1 wherein said cellulose fibers comprise 75-95 percent by weight of said base, said base includes an internal sizing of starch 0-15 percent by weight of said base, and the premolding moisture content of said base is 5-20 percent moisture by weight of said base.

10. The flong of claim 9 wherein said surface coating has a burnished set.