U.S. patent number RE30,233 [Application Number 05/600,154] was granted by the patent office on 1980-03-18 for multiple layer decorated paper, laminate prepared therefrom and process.
This patent grant is currently assigned to The Mead Corporation. Invention is credited to William C. Lane, Donald E. Moffatt.
United States Patent |
RE30,233 |
Lane , et al. |
March 18, 1980 |
Multiple layer decorated paper, laminate prepared therefrom and
process
Abstract
A decorated multiple layer paper suitable for use as a top
surface in resin impregnated abrasion resistance decorated
laminates, and the laminates prepared therefrom, said multiple
layer having a base layer and a top layer, the top layer comprising
abrasion resisting mineral particles having a hardness of 7 or more
on the Moh scale and a particle size ranging from 10 to 75 microns,
and with a printed pattern over the exposed surface of the top
layer. The multiple layer paper is made by depositing a base layer
on a paper machine forming wire, and while the base layer is in a
wet state and still supported on the forming wire, depositing the
top layer thereover. Abrasion resistant decorative laminates are
prepared from said decorated multiple layer paper by saturating
said paper with a resin, suitably a thermosetting resin followed by
uniting with a core and curing of said resin.
Inventors: |
Lane; William C. (Chillicothe,
OH), Moffatt; Donald E. (Lee, MA) |
Assignee: |
The Mead Corporation (Dayton,
OH)
|
Family
ID: |
26845277 |
Appl.
No.: |
05/600,154 |
Filed: |
July 29, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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147839 |
May 28, 1971 |
|
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Reissue of: |
237952 |
Mar 24, 1972 |
03798111 |
Mar 19, 1974 |
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Current U.S.
Class: |
428/207; 156/277;
162/181.6; 162/186; 264/132; 427/203; 427/205; 428/219; 428/328;
428/329; 442/412; 442/417 |
Current CPC
Class: |
B32B
29/00 (20130101); B44C 5/0476 (20130101); D21H
27/28 (20130101); Y10T 442/699 (20150401); Y10T
442/693 (20150401); Y10T 428/24901 (20150115); Y10T
428/256 (20150115); Y10T 428/257 (20150115) |
Current International
Class: |
B32B
29/00 (20060101); B44C 5/00 (20060101); B44C
5/04 (20060101); D21H 27/28 (20060101); D21H
27/18 (20060101); B32B 005/16 () |
Field of
Search: |
;428/195,207,211,329,331,323,409,219,288,290,328
;427/203,204,205,261,288 ;162/181C,186,128,126 ;156/277,279
;264/131,132,137 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Silverman; Stanley S.
Attorney, Agent or Firm: Arnold, White & Durkee
Parent Case Text
REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending application
Ser. No. 147,839, filed May 28, 1971 now abandoned.
Claims
What is claimed is:
1. An abrasion resistant laminate comprising a core and a resin
impregnated cured decorated surface paper, said surface paper,
prior to resin impregnation comprising
(a) a paper base layer;
(b) a top layer integral with said base layer and comprising from
about 2 to 100 percent by weight of abrasion resisting mineral
particles having a hardness of from 7 to 10 on the Moh scale and an
average particle size ranging from 10 to 75 microns, and
(c) printing applied on the exposed outer surface of said top
layer.
2. The abrasion resistant laminate of claim 1 wherein said resin is
a thermosetting resin.
3. The abrasion resistant laminate of claim 1 wherein said top
layer includes fibers.
4. The abrasion resistant laminate of claim .[.2.]. .Iadd.3
.Iaddend.wherein said top layer comprises from 10% to 50% of said
mineral particles and from 90% to 50% of said fibers.
5. The abrasion resistant laminate of claim 1 wherein said mineral
particles are alumina.
6. The abrasion rsistant laminate of claim 1 wherein said mineral
particles are silica.
7. The abrasion resistant laminate of claim 1 wherein said mineral
particles are silicon carbide.
8. The abrasion resistant laminate of claim 1 wherein said mineral
particles are a mixture of tungsten carbide and borron carbide.
9. The abrasion resistant laminates of claim 1 wherein said top
layer has a basis weight ranging from 1 to 20 lbs. per ream of 3000
sq. ft.
10. The abrasion resistant laminate of claim 1 wherein said base
layer comprises fibers.
11. The abrasion resistant laminate of claim 9 wherein said base
layer has a basis weight ranging from 10 to 100 lbs. per ream of
3000 sq. ft.
12. The abrasion resistant laminate of claim 1 wherein said base
layer comprises fibers and opacifying pigments, and has a basis
weight ranging from 30 to 100 lbs. per ream of 3000 sq. ft. and
said top layer comprises from 10% to 50% alumina having a particle
size distribution of 96% in the size range of 20 to 60 microns and
90% to 50% of bleached hardwood fibers, said top layer having a
basis weight ranging from 4 to 14 lbs. per ream of 3000 sq. ft.
.Iadd.13. An abrasion resistant laminate comprising a core and a
resin impregnated printed decor paper, said printed decor paper
comprising:
(a) a base paper layer of fibers and opacifying pigments; and
(b) integral with said base paper layer a printed layer comprising
a mixture of abrasion resisting mineral particles having a hardness
of 7 to 10 on the Moh scale and print receptive fibers, the fibers
and abrasion resisting mineral particles being present in said
printed layer in an amount and size to impart printability to the
printed surface of the printed layer and to provide such abrasion
resistance to said decor paper that upon lamination, without the
presence of overlay paper, the resulting laminate has a wear rate
of under 0.08 gm/100 cycles and a minimum of 400 cycles in the NEMA
Method LD1-2.01 abrasion test, the printing on said printed layer
being on the surface opposite the surface integral with said base
layer. .Iaddend. .Iadd.14. The abrasion resistant laminate of claim
13 wherein said base paper layer has a dry basis weight ranging
from 30 to 100 lbs. per ream of 3000 sq. ft. and said printed layer
has a dry basis weight ranging from 4 to 14 lbs. per ream of 3000
sq. ft. .Iaddend. .Iadd.15. The abrasion resistant laminate of
claim 13 wherein said printed layer includes a small amount of
adhesive. .Iaddend. .Iadd.16. The abrasion resistant laminate of
claim 15 wherein said adhesive is starch. .Iaddend. .Iadd.17. The
abrasion resistant laminate of claim 13 wherein said decor paper
includes a thin fiber layer over said printable layer. .Iaddend.
.Iadd.18. An abrasion resistant laminate comprising a core and a
resin impregnated printed decor paper, said printed decor paper
comprising:
(a) a base paper layer;
(b) integral with said base paper layer a printed layer comprising
a mixture of abrasion resisting mineral particles having a hardness
of 7 to 10 on the Moh scale and print receptive fibers, the fibers
and abrasion resisting mineral particles being present in said
printed layer in an amount and size to impart printability to the
printed layer and to provide such abrasion resistance to said decor
paper that upon lamination, without the presence of overlay paper,
the resulting laminate has a wear rate of under 0.08 gm/100 cycles
and a minimum of 400 cycles in the NEMA Method LD1-2.01 abrasion
test; and
(c) the printing on said printed layer being on the surface
opposite the
surface integral with said base paper layer. .Iaddend. .Iadd. 19.
The abrasion resistant laminate of claim 18 wherein said base paper
layer has a dry basis weight ranging from 30 to 100 lbs. per ream
of 3000 sq. ft. and said printed layer has a dry basis weight
ranging from 4 to 14 lbs. per ream of 3000 sq. ft. .Iaddend..Iadd.
20. An abrasion resistant laminate comprising a core and a resin
impregnated printed decor paper, said printed decor paper
comprising:
(a) a base paper layer of fibers and opacifying pigments; and
(b) integral with said base paper layer a printed layer comprising
a mixture of abrasion resisting alumina particles, print receptive
fibers and starch, the fibers and abrasion resisting alumina
particles being present in said printed layer in an amount and size
to impart printability to the printable surface of the printed
layer and to provide such abrasion resistance to said decor paper
that upon lamination, without the presence of overlay paper, the
resulting laminate has a wear rate of under 0.08 gm/100 cycles and
a minimum of 400 cycles in the NEMA Method LD1-2.01 abrasion test,
the printing on said printed layer being on the surface opposite
the surface integral with said base paper layer. .Iaddend.
.Iadd.21. The abrasion resistant laminate of claim 20 wherein said
base paper layer has a dry basis weight ranging from 30 to 100 lbs.
per ream of 3000 sq. ft. and said printed layer has a dry basis
weight ranging from 4 to 14 lbs. per ream of 3000 sq. ft.
.Iaddend..Iadd. 22. The abrasion resistant laminate of claim 20
wherein said decor paper includes a thin fiber layer over said
printed layer. .Iaddend.
Description
BACKGROUND OF THE INVENTION
(1) Field of the invention
The present invention relates to laminates, more particularly to
laminates having a high degree of abrasion resistance and suitable
for table and counter tops, wall panels, floor surfacing, tableware
and the like.
(2) Description of the prior art
Typically, laminates may be made from papers or fabrics by
impregnating them with resins of various kinds, assembling several
layers and consolidating the assembly into a unitary structure
while converting the resin to a cured state. Resins used may be any
selected from phenolics, aminoplasts, polyesters, polyurethanes,
epoxy resins and the like. Consolidation of the layers to a unitary
laminated structure may involve pressures ranging from essentially
zero (with contact only between the layers comprising the final
laminate) to 2000 lb. per sq. in. or more. Curing or setting of the
resins may be accomplished at room temperature, or elevated
temperatures (of the order of 150.degree.-180.degree. C.) to reduce
the time required for curing.
The selection of the paper or fabric to be used, and the resin for
impregnation is governed by the intended end-use of the finished
laminate. For some end uses, surface decoration is not required or
wanted, but in many instances colors and/or patterns are desired to
add eye appeal to the finished laminate. While color and/or pattern
decoration may be wanted for an outer surface of the laminate, the
core or base functions primarily as a strengthening support, and
may comprise wood, such as plywood, multiple layers of unbleached
or dark colored paper or cloth, and may utilize dark colored, less
expensive impregnating resins, such as phenolic resins.
When decorated laminates are desired, an outer surface layer,
hereinafter called "decor," is used to cover the core layer or
layers. This colored or decorated paper, may be pigmented with
titanium dioxide and/or other opacifying pigments to mask the
dark-colored core stock. The decor layer may be impregnated with a
wide variety of resins, which may be applied to the decor in latex
form, or as solutions in suitable solvents.
To impart wear and/or abrasion resistance to such decorated
laminates, it has long been the practice to place a
resin-impregnated surfacing paper, hereinafter called "overlay"
over the decor sheet. Upon consolidating the laminate, generally
under heat and pressure, the overlay sheet becomes transparent,
permitting the printed pattern to be seen. More recently, particles
of silica have been incorporated in overlay papers to give added
abrasion resistance to laminates incorporating them. Likewise,
printed decor papers have been coated with resin syrups containing
abrasion resisting particles of silica, sometimes with added fibers
or micro-crystalline cellulose. All the known prior art relating to
abrasion resistant laminates applies a wear layer of some type over
the printed pattern.
SUMMARY OF THE INVENTION
This invention relates to a multiple layer decor paper having
abrasion-resisting mineral particles incorporated in the top layer
thereof and having printing on the surface of said top layer, the
paper being adapted to saturation with resins and incorporation
into wear resistant decorative laminates, and to decorative
laminates produced therefrom.
In one embodiment, the multiple-layer decor paper of this invention
has a base layer of fibers and opacifying fillers, with a top layer
comprising fibers and abrasion resistant mineral particles. An
intermediate layer may be provided and contain decorative
inclusions such as planchets or sequins, chopped foil or the like.
The top surface of the paper is printed to provide the desired
appearance, color and/or pattern desired in a completed
laminate.
Typically, the abrasion resistant decorative laminates of this
invention have a top surface ply of resin impregnated printed decor
paper of this invention bonded to a base or core. No overlay is
required. Surprisingly, even though the printing is applied on or
over the top layer of the paper, and thus over the wear-resisting
mineral particles incorporated therein, standard NEMA abrasion
tests give wear rates well under 0.08 gm./100 cycles, and require
up to 3000 cycles or more to the end-point (this being taken as the
point where one-half the printed pattern has been abraded away). By
contrast, prior art laminates with conventional decor papers
require the use of overlay papers to meet the NEMA Class A
specification of 400 cycles and a wear rate of 0.08 gm./100
cycles.
So far as we know, no one prior to our invention has incorporated
abrasion resisting mineral particles in a top layer of a
multi-layer decor paper, printed over this top layer (and thus over
the abrasion resisting mineral particles), and, incorporated such
paper in a laminate with no overlay to achieve the desired high
abrasion resistance in the finished laminate. With the decorative
pattern applied over the abrasion resistant layer, it is indeed
unexpected that even nominal abrasion resistance is obtained, let
alone values several times greater than that prior achieved with
conventional overlay papers.
Accordingly, it is an object of this invention to provide a
multi-layer decor paper having abrasion resisting mineral particles
incorporated in the top layer thereof, with decorative printing
applied over said top layer, such printed multi-layer decor being
adapted to impregnation with resins to produce abrasion resistant
decorative laminates.
It is a further object of this invention to provide a decor paper
having improved quality of printing applied thereto.
It is yet another object to provide abrasion resistant laminates of
improved post-forming characteristics.
Another object of this invention is to provide simplified methods
for producing decor papers and laminates prepared therefrom, which
laminates exhibit unusually high resistance to abrasion, without
the need to incorporate overlays therein.
These and other objects will become apparent from the description
which follows.
DESCRIPTION OF THE INVENTION
In the accompanying drawings:
FIG. 1 is a diagrammatic, greatly enlarged elevational section
through the printed, multiple layer decor paper of this
invention;
FIG. 2 is a diagrammatic, elevational section through a decorated,
abrasion resistant laminate of this invention; and
FIG. 3 is a graphical showing of abrasion resistance of the
decorative laminates of this invention as a function of the amount
of alumina added to the decor paper of this invention.
(1) Multiple layer printed decor
The multiple layer printed decor of this invention has a base layer
comprising fibers and most often, opacifying pigments such as
titanium dioxide, although for some end uses of laminates where
opacity of the decor is not required, the base layer may be free of
opacifying pigments. Additionally, the base layer may contain
strengthening agents, and formation and retention aids, all as
known in the art. The weight per ream of the base layer is not
critical, and may range from 10 to 100 lbs. or more per ream of 500
sheets, 24".times.36" (3000 sq. ft.) A preferred range is from 30
to 100 lbs./3000 sq. ft., and very suitable opaque decors can be
produced from base layers of 60 lbs./3000 sq. ft.
Such base layers are formed on the wire of a conventional paper
machine having one or more secondary headboxes, with the fiber
stock for the base layer delivered to the forming wire by means of
a primary headbox, all as well known in the art.
To the formed, wet base layer, while still carried by the forming
wire of the paper machine is added a top layer comprising abrasion
resisting mineral particles. This top layer may also include
fibers, and a range of mineral particles to fibers from 100%
mineral particles to 5% mineral particles is useful. A preferred
range is from 10% mineral particles to 50% mineral particles, with
the balance made up of fibers, and excellent results are obtained
with 25% mineral particles and 75% fibers. In general, the base
layer must be fairly well formed but not too free of water, prior
to application of the top layer, to allow the top layer components
to partially mix and combine with the base layer. The dandy roll
and wet presses help to accomplish the bonding together of the base
and top layers, but the top layer will consist essentially of the
composition as applied from the secondary headbox.
Generally speaking the mineral particles are adequately retained in
the top layer by entanglement with the fibers present. However, if
more positive retention is desired, a small amount of an adhesive
such as starch may be incorporated in the top layer, or a thin
layer of additional fibers may be applied over the top layer to
intermingle and bond the mineral particles therein. Such additional
fibers are suitably applied by a tertiary headbox, in an amount of
the order of 2 lbs./3000 sq. ft.
Depending on the end-use properties desired in the laminates to be
manufactured using the multiple layer decor of this invention, the
amount of top layer applied to the base layer can range from 1 to
20 lbs./3000 sq. ft., with a preferred range of 4 to 14 lbs./3000
sq. ft. (dry basis). Excellent results are obtained with a top
layer amounting to 4 to 10 lbs./3000 sq. ft. dry basis.
The abrasion resisting mineral particles comprising the top layer
are selected from materials having a hardness of 7 or more on the
Moh hardness scale. Such materials as silica, alumina, alundum,
corundum, emery, spinel, as well as other materials such as
tungsten carbide, zirconium boride, titanium nitride, tantalum
carbide, beryllium carbide, silicon carbide, aluminum boride, boron
carbide, diamond dust, and mixtures thereof may be used. The
suitability of the abrasion resisting mineral particles will depend
on such factors as availability and cost of a particular material,
particle size available and color. For very light or white
background colors, it is desirable to use essentially colorless
mineral particles, such as alumina or silica. On the other hand,
color of the mineral particles is not critical for colored decor
papers, since the print patterns are applied over the surface
thereof. Considering cost, availability, hardness, particle sizes
available and lack of color, alumina is a preferred mineral for
incorporation in the top layer.
The average particle size and particle size distribution of the
mineral particles used in producing the multiple layer decor of
this invention are quite important. Very fine particles of 2
microns or less, such as exhibited by the more conventional mineral
fillers used in printing papers do not yield the desired high
abrasion resistance in laminates. A useful range of particle size
according to this invention is from 10 micron average particle size
up to 75 micron average particle size. Average particle sizes much
over 75 microns are coarse enough to interfere with printing
detail, and may cause undue wear on caul plates. Also, fairly
closely sized mineral particles are preferred to those having a
wide range of particle diameters. A preferred average particle size
of 40 microns has given excellent results. Alumina (Moh hardness of
9) with an average size designation of 40 microns and having the
following size distribution is available from Micro Abrasives
Corporation of Westfield, Mass. under the grade designation
"Microgrit WCA-40" and is well-suited for our purposes:
______________________________________ Size, microns: Percent by
weight ______________________________________ 60 and over 4 50-60
17 40-50 29 30-40 38 25-30 12 Under 25 0
______________________________________
As may be seen from the data, 67% of this material falls in the
size range of 30 to 50 microns and 96% in the size range of 25-60
microns, and is a fairly closely sized material.
After deposition of the top layer over the base layer by means of a
secondary headbox on the paper machine, the wet, double layer web
is pressed, dried and may be calendered, all as known in the art,
followed by application of a decorative printed pattern to the
surface of the top layer to yield the multiple-layer decor paper of
this invention, as shown in the diagrammatic vertical section of
FIG. 1.
(2) Abrasion resistant laminate
The decorated, abrasion resistant plastic laminate of this
invention is prepared by treating or impregnating the printed
multiple layer decor of FIG. 1 with a suitable resin, drying and
assembling the impregnated multiple layer decor as the surface
layer, printed side out over a base or core and consolidating the
assembly as by use of heat and pressure to cure the resin therein.
A typical resulting laminate, such as is shown in diagrammatic
vertical section in FIG. 2, although it does not contain an overlay
over the print surface, still exhibits excellent abrasion
resistance and high quality decorative print quality, making it
suitable for numerous applications where severe wear may be
expected, such as furniture, table tops and counter tops, flooring
and the like. This is a wholly unexpected result, since the print
pattern has not been covered with a wear-resisting layer such as an
overlay paper of a coating of abrasion resisting material over the
print pattern.
It should be evident that the key feature of this invention centers
on achieving high abrasion resistance in a finished, decorative
laminate by use of a multiple layer structure in a decor surface
ply, the abrasion resistance being attributable to abrasion
resisting mineral particles comprising the outer surface layer of
the decor, with the printed pattern applied over this surface
layer. Thus, the core of the laminate may be of any desired type,
and such cores as wood, particle board, plaster board, asbestos
board and the like are contemplated as being within the scope of
the invention, as well as the commonly used plies of unbleached
kraft paper impregnated with resins such as phenol-aldehyde
resins.
Similarly, the base layer of the multiple layer decor of this
invention may utilize fibers of a wide variety, these being
selected to impart desired properties in finished laminates to meet
particular end-use requirements. For example, the base layer may
comprise asbestos or glass fibers where flame resistance is
desired, and synthetic organic fibers may be used, such as nylon,
rayon, acrylic, polyolefin and the like.
Selection of the resin for impregnation of the multiple layer
printed decor will largely be governed by the intended end use of
the finished laminate. Aminoplasts such as melaminealdehyde resins,
acrylics such as polyacrylonitrile, polyester resins such as
diallyl phthalate, phenolic resins, polyurethanes, and epoxy resins
may be used.
The various embodiments of the invention will become apparent from
the examples which follow. In the examples, the laminates of the
invention, which incorporate the printed multiple layer decor of
the invention were evaluated for abrasion resistance according to
NEMA Method DL1-2.01. Values reported are the number of abrasive
cycles required to reach an end point, which is taken as the point
where one-half of the decorative print pattern has been abraded
away. The wear rate is reported as the weight lost by the test
laminate per 100 revolutions of the abrading wheels of the test
instrument, the Taber abrasor. It should be noted that accepted
industry standards for Class A laminates (suitable for table and
counter tops) is a minimum of 400 cycles, with a wear rate not to
exceed 0.08 gm. per 100 revolutions.
Printing quality of the multiple layer decors and laminates
prepared therefrom was measured by measuring the ink receptivity of
the surface of the top layer. Using a proof press and a uniform
halftone plate, decor samples were printed under controlled
standardized conditions using a constant metered amount of black
ink on the plate. Reflectance of the resulting print was measured
by a reflectance measuring instrument known as a "Densichron" to
give numerical values representative of the blackness of the
printed image, the blacker image resulting when the decor surface
layer is more receptive to ink. Accordingly, the lower the
Densichron reading, the better the printed result.
EXAMPLE 1
Bleached alpha pulp was beaten to a freeness of 500 ml. (Canadian
Standard) and formed on a paper machine into a base layer weighing
22 lbs./3000 sq. ft. (dry basis). To the wet base layer on the
foaming wire of the paper machine was added, by means of a
secondary headbox, 10 lbs./3000 sq. ft. (dry basis) of a mixture of
1 part bleached alpha pulp and 1 part 325 mesh silica
(substantially 100% finer than 44 microns). The double layer decor
so formed had a total basis weight of 32 lbs./3000 sq. ft. (dry
basis), with a silica content of 15.6%, based on total decor, most
of the silica being retained in the top layer. After pressing,
drying and calendering, the exposed side of the top layer was
printed with a wood grain pattern. This printed double layer decor
was then impregnated with a melamine resin and assembled, with six
plies of corestock, as the top ply (printed side out) of a
laminate. After pressing and curing, the laminate showed an
abrasion resistance of 350 cycles and a wear rate of 0.015 gm./100
cycles. By comparison, a laminate made from the decor comprising
the base layer only, and having the same print pattern, had an
abrasion resistance of 100 cycles and a wear rate of 0.059 gm./100
cycles. Thus, the double layer decor of this invention improved
abrasion resistance by a factor of 3.5, and wear rate by a factor
of almost 4.
EXAMPLES 2 THROUGH 8 INCL.
In the examples which follow, the same base layer was used
throughout, as follows: 31 parts of bleached softwood pulp, 25
parts bleached hardwood pulp and 44 parts of titanium dioxide were
blended and refined to a freeness of 425 to 450 ml. (Canadian
Standard). This furnish included 0.25 part of a dispersing agent
for the dioxide and 1.5 parts of a wet strength agent. This
composition was delivered to the primary headbox of a paper machine
at a rate to form a base layer of 66.3 lbs./3000 sq. ft. (dry
basis). A portion of the base layer was pressed and dried without
application of any top layer, for use as a control in connection
with the examples representing the invention. To a further portion
of the base layer, water was added by means of a secondary headbox
to check on the amount of base layer washed through the paper
machine wire by reason of the application of a top layer, using the
same secondary headbox. The base layer prepared in this manner had
a basis weight of 60.5 lbs./3000 sq. ft. (dry basis).
A fiber component for use in the top layer, in combination with
various kinds of abrasion resisting mineral particles, comprised
bleached hardwood pulp refined to a freeness of 425 ml. (Canadian
Standard). The fiber component was mixed in various ratios with a
variety of abrasion resistant mineral particles, then applied by
means of a secondary headbox to the wet primary layer on the wire
of the paper machine. The double layer web, in each case, was then
pressed, dried and calendered. Following this, the same printed
pattern was applied to the exposed side of the top layer of the
several different examples.
Each of the double layer printed decors was then impregnated with a
50% solution of the same melamineformaldehyde resin to give a
48-52% resin content and dried to a volatile content of about 6%.
Laminates were then prepared by employing the resin impregnated
multiple layer decors as surface sheets, printed side out, over six
sheets of corestock. Pressing and curing were under the same time,
temperature and pressure conditions in each case.
__________________________________________________________________________
Control Example plus Control H.sub.2 O 2 3 4 5 6 7 8
__________________________________________________________________________
Top layer composition: Hardwood fibers, percent 50 50 50 50 50 50
50 40.mu. Al.sub.2 O.sub.3, percent 50 50 90.mu. Al.sub.2 O.sub.3,
percent 50 50 40.mu. SiC, percent 50 35-40.mu. Norbide 320.sup.3 50
50 Physical properties: Basis wt., base layer 66.3 60.5 60.5 60.4
60.5 60.5 60.5 60.5 60.5 Basis wt., top layer 6.5 8.5 4.6 5.2 4.4
6.3 7.8 Basis wt., total 66.3 60.5 67.0 69.0 65.1 65.7 64.9 66.8
68.3 Ash, total percent 38.6 38.2 38.8 38.5 37.4 36.2 37.3 39.7
40.2 Ash, TiO.sub.2, percent 38.6 38.2 34.6 33.5 35.5 35.2 35.6
34.6 33.9 Mineral particles, percent 4.2 5.0 1.9 1.0 1.7 5.1 6.3
Abrasion tests on laminates: Cycles to end point 93 625 783 233 208
1.917 3,200 3,833 Wear rate, gm./100 cycles 0.077 0.0111 0.0071
0.0281 0.0387 0.0033 0.0023 0.0018 Printing evaluation:
Densichron-decor 30.0 29.0 27.0 28.0 26.0 30.0 38.0 37.0
Densichron-laminate 13.5 11.0 10.5 11.0 10.5 13.0 24.5 21.5
__________________________________________________________________________
.sup.3 Norbide is a mixture of tungsten carbide and boron carbide
having hardness in excess of 9 on the Moh scale.
EXAMPLES 9 THROUGH 16 INCL.
In this series of examples, the base layer as used in Examples 2
through 8 was used throughout. The top layer utilized the same
hardwood fiber component in 1:1 ratios with alumina of different
particle sizes to show the relationship between particle size and
abrasion resistance of laminates, as well as relative print
quality, other factors being held constant. Results are tabulated
below.
______________________________________ Av. Alumina Densi- Abra-
Resistance particle in total chron- sion wear, size, decor, lami-
cycles g./100 .mu. percent nate to E.P. cycles
______________________________________ Control 0 18.5 100 0.0710
Example No.: 9 40 3.3 16.8 767 0.0091 10 40 4.6 16.3 900 0.0076 11
40 4.9 15.0 944 0.0070 12 60-65 3.5 16.5 1,050 0.0062 13 60-65 4.0
18.0 1,087 0.0056 14 75 2.7 16.7 210 0.0271 15 75 3.5 15.5 342
0.0142 16 90 2.5 15.8 450 0.0152
______________________________________
As may be seen, optimum abrasion resistance is obtained in the
particle size range of 40 to 65 microns. In all cases, printing
quality, as judged by Densichron readings, was equal to or somewhat
better than the control.
EXAMPLES 17 THROUGH 20
Using the base layer of Example 2, the top layer was varied by
using a mixture of two different sized alumina powders, one being
closely sized at 60 to 95 microns and the other being an unsized
fraction having particles ranging from 1 to 60 microns, and a
weight-average size of 40 microns. These were compared with
laminates having closely sized 40 micron alumina in the top
layer.
__________________________________________________________________________
Example number 17 18 19 20
__________________________________________________________________________
Top layer composition: Bleached hardwook pulp, percent 50 50 50 60
40.mu. alumina 50 40 60-65.mu. alumina 33 26.4 Unsized alumina 17
13.6 Physical properties: Basis wt, base layer 58.0 59.0 59.5 57.5
Basis wt, top layer 5.5 5.5 5.5 5.0 Basis wt, total 63.5 61.5 65.0
62.5 TiO.sub.2, percent 36.2 36.2 36.2 36.4 Alumina percent 3.8 3.8
3.0 2.1 Abrasion tests: Cycles to end point 550 833 664 625 Wear
rate, gm./100 cycles 0.0090 0.0080 0.0106 0.0106 Ink receptivity:
Densichron-laminate 18.0 16.5 16.0 16.8
__________________________________________________________________________
From this data, it may be seen that closely sized 40 micron alumina
gives somewhat better abrasion resistance than the mixture,
although all these examples meet NEMA standards for Class A
laminates.
EXAMPLES 21 THROUGH 25 INCL.
In this series of examples, using the base layer of Example 2, the
ratio of fibers to 40 micron alumina was varied over wide limits.
The following tabulation shows the results obtained.
______________________________________ Example number 21 22 23 24
25 ______________________________________ Top layer composition:
Bl. hardwood fibers, per- cent 80 70 40 20 0 40.mu. alumina,
percent 20 30 60 80 100 Physical properties: Basis wt., base layer
58.5 59.0 60.5 61.0 59.5 Basis wt., top layer 5.5 4.5 3.5 4.3 2.0
Basis wt., total 64.0 63.5 64.0 65.3 61.5 TiO.sub.2, percent 36.5
37.1 37.7 37.2 38.6 Alumina, percent 2.2 2.4 3.4 4.9 2.2 Abrasion
tests: Cycles to end point 442 552 787 1,210 810 Wear rate, gm./100
cycles 0.0131 .0106 .0070 .0051 .0066 Ink receptivity: Densichron-
laminate 15.3 16.0 16.3 16.5 17.5
______________________________________
These examples show that, as the proportion of fibers decreases in
the top layer, abrasion resistance generally increases. While
Example 25, containing no fiber in the top layer shows a decrease
in abrasion resistance, note that the weight of top layer applied
is only 2 lbs. per 3000 sq. ft.
EXAMPLES 26 THROUGH 34 INCL.
In these examples, the base layer composition was the same and
consisted of:
______________________________________ Parts
______________________________________ Bleached softwood sulfite
pulp 27.7 Bleached hardwood sulfite pulp 27.7 Bleached softwood
sulfate pulp 27.7 Titanium dioxide 2.0 Diatomaceous earth 14.9 Zinc
oxide 2.9 Dyes to produce brown color 6.49
______________________________________
This composition was processed in conventional paper-making
equipment, and refined to a freeness of 425 ml. (Canadian
Standard). It was delivered to the primary headbox of a paper
machine and formed into a base layer of 60 lbs. per ream of 3000
sq. ft.
The top layer, applied over the base layer by a secondary headbox,
consisted of bleached hardwood sulfite and closely sized 40 micron
alumina (available from Micro Abrasives Corp. and identified as
Microgrit WCA040). The amount of top layer applied as well as the
ratio of fibers to alumina were varied as shown in the following
tabulation.
The multi-layer decor papers produced in these examples were
printed, saturated with a melamine resin and made into laminates
according to Example 2. Tests of the papers and laminates are set
forth in the following tabulation.
__________________________________________________________________________
Example number Control 26 27 28 29 30 31 32 33 34
__________________________________________________________________________
Top layer composition: Fibers, percent 50 50 50 50 50 50 50 67 67
40.mu. alumina, percent 50 50 50 50 50 50 50 33 33 Physical
properties: Basis wt., base layer 59.6 62.0 59.6 61.0 59.6 61.0
59.6 59.6 59.6 6.15 Basis wt., top layer 4.9 7.0 8.0 8.2 9.0 12.0
13.9 8.4 8.5 Basis wt., total 59.6 66.9 66.6 69.0 67.8 70.0 71.6
73.5 68.0 70.0 Total ash, percent 20.2 22.9 23.8 24.9 24.3 24.4
25.5 26.3 23.0 23.2 Ash, base, percent 20.2 18.8 18.1 17.9 17.8
17.6 16.8 16.4 17.8 17.8 Alumina, percent 0 4.1 5.7 7.0 6.5 6.8 8.7
9.9 5.2 5.4 Abrasion tests: Cycles to E.P. 130 1,100 1,100 1,500
1,300 1,575 1,900 2,125 1,140 1,150 Wear rate, gm./100 c .0650
.0057 .0055 .0041 .0044 .0041 .0040 .0042 .0063 .0051 Ink
receptivity: Densichron-decor 41.0 39.0 36.0 35.5 37.0 36.0 35.5
33.5 36.0 36.0 Densichron-laminate 31.2 32.0 30.1 30.0 32.5 29.3
28.0 26.7 28.5 29.4
__________________________________________________________________________
FIG. 3 has been constructed from the data obtained in these
examples, and shows the relationship between abrasion resistance of
the laminate and the amount of alumina in the top layer. Denischron
data show that, in each case, ink receptivity of the double layer
decor paper is improved over the control. Visual examination of the
completed laminates confirms this. The improvement in printing
quality is probably traceable to the presence of relatively fine
hardwood fibers and closely sized mineral particles in the top
surface of the double layer decor.
It is also interesting to note that, in each case, the final color
of the laminate was indistinguishable from the final color of the
laminate prepared from the control (base layer only), even though
no coloring dyes or pigments were incorporated in the top layer.
This indicates that the top layer has become essentially
transparent following resin impregnation, pressing and curing.
EXAMPLE 35
In this example, the base layer of Example 2 was used. To this
layer, while on the wire of a paper machine, was added an
intermediate layer having a composition of 50 parts bleached
hardwood sulfite fibers and 50 parts of 40-micron alumina to which
was added a sufficient quantity of sequins cut from aluminum foil
to yield approximately 100 sequins in each 10 sq. inches of the
intermediate layer. Over the surface of the intermediate layer,
while it and the base layer were still carried by the wire of the
paper machine, a top layer of 50 parts bleached hardwood sulfite
fibers and 50 parts 40-micron alumina was added by means of a third
headbox. The resultant 3-layer product was pressed dried,
calendered and printed to yield a multiple layer decor. The base
layer had a basis weight of 60.5 lbs./3000 sq. ft., the
intermediate layer a basis weight of 3.0 lbs./3000 sq. ft. and the
top layer a basis weight of 2.8 lbs./3000 sq. ft. for a total of
66.3 lbs./3000 sq. ft.
This three layered decor was incorporated in a laminate according
to Example 2. When tested, the laminate showed an abrasion
resistance of 1500 cycles and a wear rate of 0.0046 gm./100
cycles.
EXAMPLES 36 THROUGH 38 INCL.
Using the base layer of Example 2, top layers using blends of
bleached hardwood sulfite pulp and cotton linters were used, with
40 micron alumina as the abrasion resisting mineral particles. The
results are tabulated below:
______________________________________ Example number Control 36 37
38 ______________________________________ Top layer composition:
Bleached hardwood pulp, percent 0 20 35 67 Cotton linters, percent
0 30 15 40.mu. alumina, percent 0 50 50 33 Physical properties:
Basis wt., base layer 58.5 59.0 59.0 61.0 Basis wt., top layer 4.0
3.8 2.8 Basis wt., total 58.5 63.0 62.8 63.8 TiO.sub.2, percent
39.9 37.4 37.5 38.1 Alumina, percent 0 1.7 1.7 1.7 Abrasion tests:
Cycles to end point 74 683 663 535 Wear rate, gm./100 cycles .0716
.0075 .0092 .0102 Ink receptivity: Densichron-decor 31.0 31.0 31.2
30.8 Densichron-laminate 16.3 16.3 15.3 15.3
______________________________________
All the laminates had adequate levels of abrasion resistance and
ink receptivity. Additionally, the laminates of Examples 36 and 37,
each of which contained cotton linters in the surface layer, showed
very acceptable post-formability, being capable of post forming to
1/2-inch radius bends with no perceptible cracking or crazing in
the bend region. Both the control and Example 38 could not be post
formed to 1/2-inch radius without objectionable cracking and/or
crazing.
EXAMPLE 39
In this example, the printed multi-layer decor paper of Example 33
was saturated with 58% of a polyester resin, then pressed at
270.degree. F. for 2 minutes at 200 p.s.i. The finished laminate
was tested for its abrasion resistance in comparison with a similar
laminate using the single layer printed decor of the control sample
for Examples 26-34, with the following results:
______________________________________ Abrasion resistance Control
Example 39 ______________________________________ Cycles to
end-point 300 500 Wear rate, gm./100 cycles 0.068 0.0484
______________________________________
EXAMPLES 40 THROUGH 43
The printed multi-layer decors of Examples 28 and 33 were each
saturated with a low pressure melamine resin and with a diallyl
phthalate resin crosslinked with styrene. The low pressure melamine
samples were pressed for 3.25 minutes at 300.degree. F. and 300
p.s.i., while the diallyl phthalate samples were cured for 9
minutes at 240.degree. F. under 50 p.s.i. with the following
results:
______________________________________ Example number 40 41 42 43
Control ______________________________________ Decor from example
number 28 33 28 33 39 Resin used.sup.1 LPM LPM DAP DAP DAP Cycles
to end-point 1.500 1.060 530 490 290 Wear rate, 0.0058 0.0073
0.0240 0.0314 0.0710 gm./100 cycles
______________________________________ .sup.1 LPM is low pressure
melamine. DAP is diallyl phthalate.
While the low pressure melamine is a harder resin than diallyl
phthalate, both show marked improvement in abrasion resistance
resulting from the decor of this invention.
EXAMPLES 44-45
Sheets of the printed multi-layer decor paper of Examples 28 and 33
were saturated with a self-crosslinking acrylic resin in latex
form. The water was evaporated and the resin cross-linked by
heating at 130.degree. C. The resultant product was suitable for
such applications as wear resistant book covers, or could be
adhered to a base or core to provide a thicker, laminated
structure.
Abrasion resistance of the cured sheets, prior to any laminating or
adhering step was as follows:
______________________________________ Example number 44 45 Control
______________________________________ Decor from example number 33
28 39 Percent acrylic resin 32 34 34 Cycles to end point 400 600
140 ______________________________________
Again, the marked improvement in abrasion resistance attained with
the printed multi-layer decor of this invention is evident.
* * * * *