Sheet material with multicolor striated pattern

A synthetic plastic sheet material having a multicolor striated pattern therein is disclosed. The synthetic plastic sheet material has a multiplicity of bands of differentially colored resin disposed within a matrix resin and the bands have striations extending longitudinally of the sheet material. Some of the bands extend angularly to others of the bands so as to provide a grid pattern. The bands of one angular orientation are disposed at a depth within the matrix material which is different from that of the bands of the other angular orientation. A multiplicity of bands of each orientation are provided across the width of the sheet material and the bands have relatively narrow striations extending longitudinally of the sheet material.

BACKGROUND OF THE INVENTION 
For more than a decade, there has been considerable effort devoted to the 
producing of synthetic thermoplastic sheet material having differentially 
colored bands or layers therein. The materials originally developed 
employing differentially colored bands are of the type illustrated in U.S. 
Pat. No. 2,985,558 granted May 23, 1961 to William P. Rowland and it can 
be seen that the bands of the differentially colored material extended in 
a direction generally parallel to the direction of extrusion. Other 
techniques for introducing differentially colored material in the body of 
the extruded sheet are shown in U.S. Pat. No. 2,632,204 to Murray and U.S. 
Pat. No. 2,803,041 to Hill et al. 
For some applications, it is extremely desirable that the differentially 
colored materials not extend in a parallel pattern to the direction of the 
extrusion and this is particularly so in the optical frame industry 
wherein patterns of varying appearance are constantly desired. Various 
techniques have been proposed to provide interruption in an otherwise 
parallel pattern for the differentially colored material, among which is 
that illustrated in U.S. Pat. No. 3,274,646 to Krystof. Techniques for 
producing unusual multilayered and swirl patterns are described in U.S. 
Pat. No. 3,443,278 and U.S. Pat. No. 3,531,828 to Jan P. Nauta and U.S. 
Pat. No. 3,422,175 to William P. Rowland. 
One of the most popular patterns over the past years has been a Havana 
pattern which effectively comprises a basketweave design wherein 
differentially colored material from a crosshead extruder is discharged 
from two series of vertically spaced ports fed intermittently by means of 
screws or the like. Such designs have proven quite popular and there have 
been patterns produced using two different colors for the bands providing 
the basketweave design. 
One of the objections to the Havana pattern has been that all of the 
components of color extend diagonally of the sheet material. There have 
been efforts to superimpose color effects which would soften the 
basketweave design which have frequently included laminating techniques. 
It is an object of the present invention to provide a novel and highly 
attractive synthetic plastic sheet material having a multiplicity of bands 
of differentially colored resin disposed within a matrix resin and in 
which the bands have striations extending longitudinally of the sheet 
material. 
Other objects and advantages of the invention will appear from the 
following description. 
SUMMARY OF THE INVENTION 
It has now been found that the foregoing and related objects are attained 
by providing a differentially colored extruded thermoplastic sheet 
material comprising a matrix of synthetic thermoplastic resin and a 
multiplicity of bands of differentially colored thermoplastic resin 
encapsulated therein, with some of the bands extending angularly to others 
of the bands so as to intersect with them to provide a grid pattern. The 
bands of one angular orientation are disposed at a depth within the matrix 
different from that of the bands of the other angular orientation. A 
multiplicity of each orientation of the bands is provided across the width 
of the sheet material, the bands having relatively narrow striations 
extending longitudinally of the sheet material. 
Other objects of the invention are attained when the bands of one angular 
orientation are of a first color, which is distinguished from that of the 
matrix and the bands of the other angular orientation are of a color 
distinguished from that of the matrix and of the bands of the first 
angular orientation, with the striations of the bands producing some 
blending of the colors of the bands of the two different angular 
orientations. The bands of one color may be above the center line of the 
sheet material and the bands of the other color may be below the center 
line. 
The foregoing objects can be attained by providing the sheet material by a 
method in which there is provided an elongated die chamber having an 
extrusion orifice and a discharge passage communicating therebetween. 
Fluid synthetic thermoplastic resin is supplied to the die chamber at a 
point spaced from the discharge passage. A differentially colored fluid 
synthetic thermoplastic resin is supplied at a multiplicity of points in 
the die chamber which are spaced along the length thereof and between the 
point of supply of the first mentioned fluid synthetic plastic resin and 
the discharge passage to produce bands of the differentially colored resin 
at the spaced points within a matrix of the first mentioned resin flowing 
about the spaced points. The composite stream of the bands within the 
matrix is then caused to flow through the perforations of a perforated 
member and thereby to provide fine striations in the bands of the 
differentially colored resin and extending in the direction of flow of the 
composite stream towards the extrusion orifice. This composite stream is 
then extruded and has the differentially colored synthetic thermoplastic 
resin encapsulated within a matrix of the first mentioned synthetic 
thermoplastic resin, with the differentially colored synthetic plastic 
resin providing generally transversely extending bands of differential 
color along the length of the extruded composite stream with fine 
striations of the differential color extending longitudinally of the 
extruded composite stream. 
The points of supply of the differentially colored fluid synthetic 
thermoplastic resin may be helically moved a limited distance along the 
length of the die chamber to produce diagonally extending bands, and they 
may be spaced above and below the center line of the die chamber. In a 
preferred aspect of the method, the differentially colored fluid synthetic 
thermoplastic resin supplied at the points above the center line is of a 
first differential color and that supplied below the center line of the 
die chamber is of a second differential color, thereby producing a 
three-color synthetic plastic material having intersecting bands of two 
different colors. Most desirably, the perforated member has a multiplicity 
of perforations therein which are spaced apart by narrow solid segments 
about which the composite stream is caused to flow to produce the 
striations. 
To practice the process, there is utilized an extrusion assembly which 
includes an extrusion die block having a chamber therein, an elongated 
extrusion orifice in one surface thereof and a discharge passage between 
the chamber and the orifice. A first feed conduit extends to the chamber 
at a point spaced to the opposite side thereof from the discharge passage 
for supplying a matrix of fluid synthetic thermoplastic resin, and at 
least one additional feed conduit to the chamber has a portion within the 
die member extending generally parallel to the extrusion orifice and 
supplies a differentially colored fluid synthetic thermoplastic resin. In 
addition, there is at least one sleeve member in the chamber extending 
genrally parallel to the extrusion orifice and it has a bore therein 
communicating with the additional feed conduit and a multiplicity of 
discharge openings communicating with the bore and opening adjacent the 
extrusion orifice. A perforated member is provided in the discharge 
passage and has a multiplicity of relatively small perforations therein, 
some of which are spaced apart by relatively narrow solid segments, 
whereby the composite stream passes through the perforations of the 
perforated member prior to discharge from the extrusion orifice. The 
differentially colored fluid synthetic plastic resin is caused to flow 
about the narrow solid segments between the perforations which results in 
flow disturbance and striations in the composite stream. 
The perforated member is preferably comprised of an insert block having 
perforations therein and a screen member retained within the insert block 
whereby the composite plastic stream passes through block perforations and 
the openings of the screen member which provides the narrow solid 
segments. A pair of sleeve members are desirably provided in the chamber 
vertically spaced above and below the center line, and distributor 
elements are disposed in the bores of the sleeve members to provide 
intermittent flow of resin through the discharge openings. The means 
driving the distributor elements to provide intermittent flow above the 
center line are driven oppositely from the direction of movement of the 
distributor element in the sleeve below the center line. 
The present invention is advantageously employed with various synthetic 
thermoplastic materials such as cellulose acetate and cellulose 
acetate/butyrate. Various dyes and pigments may be used to provide color 
or varying density of coloration to one or both plastic streams to achieve 
the visual differentiation in color, refraction or transparency. 
The term "differentially colored material" is intended to encompass 
materials which are visually distinguishable from the material of the body 
of the sheet material to provide a visual pattern effect and includes the 
use of colors or substantial lack of color distinct from that of the body 
of the sheet material and the use of the same color but distinct optical 
properties so as to produce variation in light refraction or transmission 
with resultant visual pattern effect.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
Turning now in detail to FIGS. 1-3 and 5-7 of the attached drawings, 
therein illustrated in an extruder assembly for producing a differentially 
colored synthetic plastic sheet material having spaced bands of a 
differential color at two depths within the matrix of a first color and 
especially adapted to produce a striated "Havana pattern" illustrated in 
FIG. 4. As seen in FIG. 1, an extruder assembly includes a main or matrix 
extruder generally designated by the numeral 10, a first crosshead 
extruder generally designated by the numeral 12, a second crosshead 
extruded extruder fragmentarily illustrated and generally designated by 
the numeral 14 and a die block assembly generally designated by the 
numeral 16 with the sheet material produced thereby being generally 
designated by the numeral 18. 
The die block of the assembly 16 has a large chamber therein generally 
designated by the numeral 20, a first feed conduit 22 from the main 
extruder 10, and a second feed conduit 24 from the crosshead extruder 12, 
and a third feed conduit 26 from the crosshead extruder 14. A discharge 
passage 28 extends from the chamber 20 to the extrusion orifice 30 (seen 
in FIG. 3) which is provided in the surface of the die block opposite that 
having the feed conduit 22. As also seen in FIG. 3, the depth dimension of 
the extrusion orifice 30 is controlled by the die lips 32 which may be 
adjusted by adjusting bolts (not shown). For purposes of clarity, 
illustration of heat exchange conduits, thermocouples, adjusting screws, 
drive mechanism for the screws and the like has been omitted. 
As best seen in FIGS. 2 and 3, the feed conduit 22 opens into an enlarged 
manifold 34 of circular cross section extending across the length of the 
die chamber 20 so as to supply resin from the extruder 10 across the 
entire length thereof. Seated within the die chamber 20 are a pair of 
sleeves generally designated by the numeral 36. The sleeves 36 have 
generally rectilinear opposed surfaces 38 and are spaced apart by spacing 
ribs (not shown) to provide a channel 40 therebetween aligned with the 
feed conduit 22 and the discharge passage 28. The sleeves 36 are also 
spaced from the walls of the die chamber 20 by spacing ribs (not shown) on 
the outer surfaces thereof to provide channels 42 therebetween. 
Each of the sleeves 36 has a circular bore 44 in the trailing portion 
thereof and a circular bore 46 in the leading portion thereof, and the two 
bores communicate through a feed passage 47. The bore 44 comprises the 
feed bore and is in communication with the corresponding feed conduit 24, 
26. 
As best seen in FIG. 5, the sleeves 36 each have two rows of staggered, 
elongated slot-like discharge openings 56 and 58 which have outwardly 
diverging sidewalls and through which the resin passes. Rotatably seated 
in the bores 46 are metering screws 48 with helical lands (not shown) 
which alternately discharge resin through the adjacent staggered discharge 
openings 56, 58 of the two rows as the lands rotate thereby, thus 
producing intermittent and alternate discharge through the adjacent 
staggered openings of the two rows. The screws 48 are driven by suitable 
drive means (not shown) which is connected thereto outwardly of the die 
block 16. 
Seated within the leading end of the die chamber 20 is a flow diverter 
generally designated by the numeral 50 which has a streamlined 
configuration conforming to the adjacent surfaces of the die chamber 20 
and sleeves 36. The flow diverter 50 is positioned within the die chamber 
20 by suitable means on the ends thereof (not shown) mounted within the 
die block 16. Diverter bars generally designated by the numeral 52 are 
provided in alignment with the outer row of discharge openings 56 in the 
sleeves 36. Lastly, feed members 54 are provided in the bores 44 to 
facilitate flow of resin along the length thereof. 
In the discharge passage 28 of the die block assembly 16 is positioned a 
perforated member assembly generally designated by the numeral 60. As best 
seen in FIGS. 6 and 7, the perforated member subassembly 60 is comprised 
of a metal block 62 which is provided with two rows of perforations 64 
extending across the full length thereof so that synthetic resin flowing 
through the passage 28 may pass therethrough. The lower portion of the 
metal block 62 seats in a groove 66 milled in the lower half of the die 
block assembly 16 and the upper portion is held in position by screws 68 
as seen in FIG. 2. Seated in a vertically extending slot in the metal 
block 62 is a metal screen member 70 which thus provides narrow metal 
segments in the path of flow of the resin through the perforation 64 in 
the metal block 62. As will be appreciated, the metal block 62 provides 
support for the flexible screen member 70 so that it may resist distortion 
thereof under the substantial pressures of the resin flowing through the 
discharge passage 28. 
Further details concerning the construction of preferred apparatus for 
producing the basic Havana pattern may be found in U.S. Pat. No. 3,792,945 
granted Feb. 19, 1974 to Applicant herein. 
Turning now to operation of the apparatus, fluid synthetic thermoplastic 
resin from the main extruder 10 is fed through the feed conduit 22 to the 
manifold 34 and thence into the upstream portion of the die chamber 20. 
The resin is then caused to flow about the surfaces of the sleeves 36 
through the channels 40, 42. 
Simultaneously, differentially colored fluid synthetic thermoplastic resin 
is fed from the crosshead extruders 12, 14 through the feed conduits 24, 
26 to the feed bores 44 of the sleeves 36. The resin then flows at a 
relatively uniform rate through the feed passages 47 to the bores 46. The 
screws 48 rotating within the bores 46 discharge the fluid synthetic 
thermoplastic resin on an intermittent basis through the discharge 
openings 56, 58 alternately in each of the sleeves 36, thus producing a 
discharge of resin which progresses along the length of the rows of 
discharge openings 56, 58. 
The flow diverter 50 and the flow diverter bars 52 deflect the matrix resin 
flowing through the channels 40, 42 into the discharge openings 56, 58 so 
as to encapsulate the differentially colored resin issuing therethrough. 
In this manner, the differentially colored resin is completely 
encapsulated within the main stream of the matrix resin and smearing is 
avoided. Moreover, the diverted matrix resin passing into the discharge 
openings 56, 58 facilitates the removal of the differentially colored 
resin therefrom. 
The composite resin stream of resin containing the encapsulated 
differentially colored resin from the crosshead extruders 12, 14 passes 
towards the die lips 32 through the discharge passage 28. As it flows 
therealong, it encounters the perforated member subassembly 60 and must 
flow through the perforations 64 of the metal block 62 and the openings of 
the screen member 70 therein. As the differentially colored stream 
components flow through the screen member 70, the narrow solid segments 
provided by the mesh of the screen member 70 distort the flow and cause a 
portion of the otherwise crisply defined diagonal bands of color to be 
distorted longitudinally. 
Typical sheet material which may be produced in accordance with the 
apparatus previously described is illustrated in FIG. 4 of the 
accompanying drawings. The plan view FIG. 4 shows the diagonal bands of 
color 72 from the upper sleeve 36 and the diagonal bands of color 74 from 
the lower sleeve 36, both extending diagonally to the center line of the 
sheet material and crossing each other at various points to produce a 
basketweave pattern. However, instead of sharply delineated bands 
extending only diagonally, there are striations 76 which extend 
longitudinally of the sheet material effected by the metal mesh of the 
screen member 70. The plan views, FIGS. 8 and 9, respectively, illustrate 
the disposition of the differentially colored bands within the matrix 
resin in the lower and upper portions of the sheet material. 
As has been indicated previously, the grid pattern can be varied to produce 
different angular arrangements of the intersecting bands, and two 
differentially colored resins can be utilized to produce intersecting 
bands of different colors. 
Various other constructions for the perforated member may be employed so 
long as the narrow solid segments are dimensioned to effect the desired 
minor interference with the flow of the differentially colored bands to 
produce the narrow longitudinal striations. Although boring a block to 
provide fine or narrow wall segments is possible, the wall sections tend 
to be weak. Similarly, a self-supporting wire mesh tends to be limited by 
the wire thickness necessary to achieve desired strength to resist the 
pressures producing deflection thereof. If the extruder is operated at 
relatively low pressure, other variations are more feasible. 
Various patterns may be obtained by using different combinations of screws 
or other intermittent discharge means such as paddle shaped members which 
will discharge across the entire surface of the discharge openings 56 
simultaneously, by varying the relative rates of speed of the intermittent 
discharge means, by varying their direction of rotation, by oscillating 
their speed of rotation, etc. Adjustments in the matrix resin flow are 
conveniently adjusted not only by the pressure developed in the extruder 
but also by variation in the flow restriction caused by the adjustable 
restrictor bars. 
As will be readily appreciated, the novel die block assembly required for 
the method of the present invention may be fabricated from relatively few 
parts and is simple to construct and to maintain while at the same time 
ensuring troublefree operation. Variations in pattern and color may be 
readily effected and the resultant patterns are substantially uniform 
along the length of the sheet material and have attractive characteristics 
including the longitudinal striations.