U.S. patent application number 10/481075 was filed with the patent office on 2006-03-09 for retroreflective fabrics and method of production.
Invention is credited to Michael John Sleeman, Peter Richard Smith, Peter Alan White.
Application Number | 20060051559 10/481075 |
Document ID | / |
Family ID | 9916751 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060051559 |
Kind Code |
A1 |
Sleeman; Michael John ; et
al. |
March 9, 2006 |
Retroreflective fabrics and method of production
Abstract
A retroreflective fabric having a print or coating having
retroreflective pattern areas of aligned, hemispherically coated
retroreflective microbeads. In one implementation of the invention
a breathable and/or moisture management fabric has adhered thereto
one or more arrays of dots each comprising a plurality of aligned,
hemispherically coated retroreflective microbeads in such a way
that the fabric is exposed for breathability and/or moisture
management at interstices between the dots. In an alternative
implementation, a breathable fabric has adhered thereto one or more
arrays of dots each comprising an area of fabric surrounded by an
area of aligned, hemispherically coated retroreflective microbeads
adhered to the fabric in such a way that the fabric is exposed for
breathability and/or moisture management in the dot areas.
Inventors: |
Sleeman; Michael John;
(Cheshire, GB) ; Smith; Peter Richard; (Avon,
CT) ; White; Peter Alan; (Cheshire, GB) |
Correspondence
Address: |
BRACEWELL & GIULIANI LLP
P.O. BOX 61389
HOUSTON
TX
77208-1389
US
|
Family ID: |
9916751 |
Appl. No.: |
10/481075 |
Filed: |
June 14, 2002 |
PCT Filed: |
June 14, 2002 |
PCT NO: |
PCT/GB02/02777 |
371 Date: |
May 5, 2004 |
Current U.S.
Class: |
428/143 |
Current CPC
Class: |
D06Q 1/10 20130101; D06Q
1/12 20130101; D06P 1/0012 20130101; Y10T 428/24372 20150115; G02B
5/128 20130101 |
Class at
Publication: |
428/143 |
International
Class: |
E01F 9/04 20060101
E01F009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2001 |
GB |
0114738.8 |
Claims
1-39. (canceled)
40. A method for making a retroreflective fabric, comprising the
steps of: (i) producing a sheet having a layer of microbeads
hemispherically metallised on their faces away from the sheet; and
(ii) transferring said metallised beads to a fabric, metallised
face to said fabric, in pattern areas; and performing at least one
of the steps of: (a) re-using said sheet for at least one
additional transfer of said metallic beads to a further fabric or
to a different section of said fabric, a transfer pattern being
selected to require bead transfer only from areas of said sheet
left beaded after said at least one previous transfer; and (b)
after said at least one transfer, recovering beads from said
sheet.
41. The method according to claim 40, in which said beads are
transferred in a dot pattern or a reverse dot pattern.
42. The method according to claim 40, in which said transfer is
effected through adhesive applied to said layer of microbeads on
said sheet or to said fabric in such a way that said transfer is
effective to apply said microbeads to said fabric to produce at
least one patterned area in which parts of said fabric are exposed
for at least one of the group consisting of: breathing and moisture
management.
43. The method according to claim 40, in which said beads are
transferred selectively from said sheet to said fabric.
44. The method according to claim 40, in which said fabric is
printed with a pattern of transfer adhesive and said sheet is
pressed against said fabric so that beads transfer from said sheet
to said fabric.
45. The method according to claim 40, in which said sheet is
printed with a pattern of transfer adhesive and pressed against
said fabric so that beads transfer from said sheet to said
fabric.
46. The method according to claim 44, in which said transfer
adhesive is a heat activated transfer adhesive, and said sheet and
said fabric are pressed together with heat to activate said
transfer adhesive.
47. The method according to claim 40, in which said transfer
adhesive is a polyurethane, polyamide or plastisol adhesive.
48. The method according to claim 47, in which said transfer
adhesive is a polyurethane or polyamide adhesive that cross-links
at elevated temperature.
49. The method according to claim 40, in which said sheet comprises
a paper substrate.
50. The method according to claim 40, in which said metallised
beads are attached to said sheet by a linear low density
polyethylene adhesive.
51. The method according to claim 40, in which a thin primer is
applied over said metallised beads before transfer to said
fabric.
52. The method according to claim 40, in which bead recovery is
effected by bending said sheet, whilst travelling, over a small
radius.
53. The method according to claim 52, in which said sheet is
chilled for said small radius bending operation.
54. The method according to claim 40, in which said beads on said
sheet are metallised selectively such that some beads are
metallised and others are not.
55. The method according to claim 54, in which, following
metallisation, said sheet carries areas of light transmissive beads
which are metallised and areas of light transmissive beads which
are not and in which both metallised and non-metallised beads are
transferred to said fabric.
56. The method according to claim 55, in which said non-metallised
beads are associated with at least one of the group consisting of:
colorant and light reflective material.
57. The method according to claim 56, in which said colorant and
said light reflective material is incorporated in an adhesive used
to adhere said beads to said fabric.
58. The method according to claim 40, in which a non-water-based
transfer adhesive is used for bead transfer to said fabric.
59. The method according to claim 40, said fabric being having a
width selected from the group consisting of: at least 1 metre and
at least 1.5 metres.
60. The method according to claim 45, in which said transfer
adhesive is a heat activated transfer adhesive, and said sheet and
said fabric are pressed together with heat to activate said
transfer adhesive.
Description
[0001] This invention relates to retroreflective fabrics and
methods for making them.
[0002] Retroreflective fabrics are made by printing or coating on
to a fabric a retroreflective ink or coating. In some such fabrics,
the ink coating contains microbeads hemispherically coated with
aluminium. During the printing or coating the microbeads are
randomly aligned with only a proportion of them so disposed as to
be capable of retroreflectivity.
[0003] The beads not so disposed are, in effect, wasted and also
have a deleterious effect on the daylight appearance of the fabric,
tending to give a grey cast to it.
[0004] Tapes, capable of a greater degree of retroreflectivity, are
made by embedding microbeads in an adhesive layer on a backing and
metallising the exposed hemispheres of the microbeads, then
transferring the microbeads to an adhesive coated tape so that the
metallised surfaces are embedded in the adhesive in the tape, the
microbeads now being all aligned and all contributing substantially
100% to the retroreflectivity. Retroreflective tape, whilst being
useful in many applications, is, however, of limited
usefulness.
[0005] The present invention provides retroreflective fabrics and
methods for making the same that have the degree of
retroreflectivity of a tape, or at least much more nearly so than
conventional ink-printed or coated fabrics, whilst being more
generally useful.
[0006] The invention comprises a retroreflective fabric having a
print or coating having retroreflective pattern areas of aligned,
hemispherically coated retroreflective microbeads.
[0007] The fabric may be one which is breathable, the term
"breathable" referring to the ability of the fabric to allow the
passage of air or other gases or moisture to pass through the
fabric.
[0008] Additionally or alternatively, the fabric may be one which
has moisture management properties. For example, the fabric may be
one which is intended to move moisture away from its internal
surface (for instance, a surface which may contact the skin of the
wearer) by a mechanism such as a wicking action. The fabric may
also permit rapid or gradual migration of moisture to the outer
surface of the fabric in a controlled manner where evaporation will
occur. The result of such moisture management is to keep the
internal surface of the fabric substantially dry.
[0009] The present invention allows fabrics to be produced with
highly reflective areas without unacceptably compromising the
breathability and/or moisture management properties of the
fabric.
[0010] The beads may be adhered to the fabric through a transfer
adhesive, especially one which is not water based.
[0011] The fabric is typically at least 1 metre wide, e.g. about
1.5 metres wide.
[0012] The print or coating may be applied in a dot pattern or a
reverse dot pattern. By a "dot pattern" is meant that the print or
coating is applied in a pattern of dots, eg. circular, square,
rectangular, triangular or other shaped dots separated by blank
areas, while by a "reverse dot pattern" is meant that the printing
or coating surrounds circular, square, rectangular, triangular or
other shaped blank dots. This kind of printing or coating is in
effect "solid", but leaves uncoated areas which enable the fabric
to "breathe" and/or allow the moisture management, which is of
general importance, but of particular importance in connection with
clothing intended for use eg. by fire fighters and others working
in hot environments. The print or coating may, of course, be
rendered fire retardant or flame resistant and applied to a heat
resistant fabric for such purposes.
[0013] Thus, in one implementation of the invention a fabric which
is breathable and/or has moisture management properties has adhered
thereto, e.g. by a transfer adhesive, one or more arrays of dots
each comprising a plurality of aligned, hemispherically coated
retroreflective microbeads in such a way that the fabric is exposed
for breathing/moisture management at interstices between the
dots.
[0014] In another implementation of the invention, a breathable
and/or moisture management fabric has adhered thereto, e.g. by a
transfer adhesive, one or more arrays of dots ("reverse dots") each
comprising an area of fabric surrounded by an area of aligned,
hemispherically coated retroreflective microbeads adhered to the
fabric in such a way that the fabric is exposed for
breathing/moisture management in the dot areas.
[0015] Typically within a particular array of dots or reverse dots
present within a discrete pattern area on the fabric, the minimum
area of exposed breathable and/or moisture management fabric within
such pattern area is at least about 5%, e.g. at least about 10% and
typically at least about 30%, of said pattern area. The maximum
area of exposed breathable fabric within such discrete pattern area
may be up to at least about 95%, e.g. at least up to about 90% and
typically up to about 85%, of said pattern area.
[0016] The fabric may have a "daylight" print pattern different to
the retroreflective pattern. In particular, the retroreflective
pattern may be a solid or substantially solid overall print, with a
"daylight" print pattern which is not overall or which is overall,
but in different colours in different areas. Colour may be present
in the bead areas.
[0017] The beads may have a pigment layer, which may comprise
photo-luminescent or fluorescent pigment, or they may have a
coloured film layer, or they may be embedded in a coloured adhesive
layer.
[0018] The fabric may be provided with areas of unmetallised beads,
which may comprise a colour system such as a pigment or film
coating or a coloured embedding adhesive. Unmetallised beads may be
backed by a reflective medium to import retroreflectivity.
[0019] The fabric may also comprise areas of non-aligned,
hemispherically coated microbeads.
[0020] The invention also comprises a method for making a
retroreflective fabric, comprising the steps of: [0021] producing a
sheet having a layer of microbeads hemispherically metallised on
their faces away from the sheet; [0022] transferring said
metallised beads to a fabric, metallised face to the face, in
pattern areas.
[0023] The fabric is typically one which is breathable and/or has
moisture management properties.
[0024] The beads may be transferred in a dot pattern or a reverse
dot pattern. The sheet, having had the beads transferred in the dot
or reverse dot pattern, will have substantial numbers of beads left
on it, and may be re-used for a second fabric (and a third,
perhaps, and even a fourth, depending upon the numbers of beads
removed each time), the pattern being selected to require bead
transfer only from areas left beaded after said first fabric
transfer. Such re-use of the transfer paper and/or salvaging of the
beads can improve the economics of the method of the invention.
[0025] The beads may, in any event, be transferred selectively from
the sheet to the fabric, even if not in dot or reverse dot
pattern.
[0026] The fabric may be printed with a pattern of transfer
adhesive and the sheet pressed against the fabric so that beads
transfer from the sheet to the fabric, or the sheet may be printed
with a pattern of transfer adhesive and pressed against the fabric
so that beads transfer from the sheet to the fabric.
[0027] The transfer adhesive may be one which is activated by heat
and the sheet and fabric pressed together with heat to activate the
transfer adhesive.
[0028] The transfer adhesive may be non-water-based, e.g. a
polyamide, plastisol or polyurethane adhesive that may cross-link
at elevated temperature.
[0029] It has been found that using a transfer adhesive tends to
have less of an adverse affect upon the moisture wicking ability of
a fabric, compared with some water-based reflective inks, possibly
because water-based inks tends to penetrate the fabric to a greater
extent.
[0030] The sheet may comprise a substrate such as paper, e.g. Kraft
paper.
[0031] The beads may be attached to the sheet by a linear low
density polyethylene adhesive.
[0032] A thin primer may be applied over the metallised beads
before transfer to the fabric.
[0033] When a sheet has been used for transfer printing, metallised
beads may be recovered from it for use, eg. in inks. Bead recovery
may be effected by bending the travelling sheet over a small
radius, such as a small diameter roller or edge. The sheet may be
chilled for this, which may embrittle or stiffen the adhesive and
allow the beads to pop out as the adhesive gapes over the
radius.
[0034] Embodiments of retroreflective fabrics and methods and
apparatus for making them will now be described with reference to
the accompanying drawings, in which:
[0035] FIG. 1 is a face-on view of one embodiment of a
retroreflective fabric of the invention;
[0036] FIG. 2 is a cross-section through the fabric of FIG. 1;
[0037] FIG. 3 is a view like FIG. 1 of another embodiment of
fabric;
[0038] FIG. 4 is a view like FIG. 1 of another embodiment of
fabric;
[0039] FIG. 5 is a flow diagram illustrating how fabrics according
to the invention (and other fabrics) may be manufactured;
[0040] FIG. 6 is a diagrammatic illustration of steps in the
manufacture of a retroreflective fabric;
[0041] FIG. 7 is a view of a partially unbeaded sheet after a first
bead transfer operation showing an adhesive pattern for a second
transfer;
[0042] FIG. 8 is a diagrammatic section through a fabric having
metallised and non-metallised bead areas and areas without beads;
and
[0043] FIG. 9 is a diagrammatic illustration of a bead recovery
operation.
[0044] The drawings illustrate retroreflective fabrics 11 having a
print or coating 12 having discrete retroreflective pattern areas
13 of aligned, hemispherically coated retroreflective glass
microbeads.
[0045] As mentioned above, tapes, for application to clothing such
as jackets and tabards to give night-time conspicuity by virtue of
retroreflectivity, have long been made by embedding microbeads in
an adhesive coating on a carrier so that they are hemispherically
disposed, then metallising the exposed hemispheres of the
microbeads, then transferring them en masse to an adhesive surface
of a tape so that the beads are all aligned with their metallised
hemispheres embedded in the adhesive matrix of the tape.
[0046] More recently, fabrics have been printed in patterns of
retroreflective areas by incorporating hemispherically metallised
microbeads in an ink which is used for printing more or less as a
normal printing ink. Such fabrics are, however, significantly less
retroreflective than the tapes because in the fabric the microbeads
are not aligned, which has a deleterious effect on the daylight
appearance of the fabric, tending to give a grey cast to it.
[0047] The retroreflective fabrics of the present invention, by
contrast, can have, in their pattern areas, the kind of
retroreflectivity associated with tapes.
[0048] FIGS. 1 and 2 illustrate applying to a breathable and/or
moisture management fabric 11 a print of the aligned
retroreflective microbeads in a dot pattern, dots 14 of, say,
millimetre or sub-millimetre dimensions, corresponding to the dots
printed by a silk screen printing process, constituting the pattern
areas 13. Since the dots 14 are attached to the fabric 11 by
adhesive, which tends not to be breathable, the areas 15 around the
dots 14, being free of the adhesive, allow the fabric to breath
and/or function for the purposes of moisture management.
[0049] It will be understood that each millimetre or sub-millimetre
"printing" dot will contain perhaps several hundred light
transmissive microbeads, which are typically sized in the range of
20 to 90 microns, e.g. usually about 60 microns.
[0050] FIG. 3 illustrates a fabric 11 with a reverse dot pattern,
in which the bead-free areas 15 appear as dots surrounded by beaded
area 14 in the pattern areas 13.
[0051] Colour can be present, in the usual way, of course, in the
non-beaded areas, but also in the beaded areas. The beads may be
applied, for example, to an already printed or coloured fabric 11.
For colour in the beaded areas, the beads themselves may be covered
in a pigment layer, which may contain a fluorescent or
photo-luminescent pigment, especially for daytime conspicuity, or a
"day-glow" type of colouration, or have a coloured film layer. The
beads may be embedded in a coloured adhesive layer of the
fabric.
[0052] FIG. 4 illustrates a fabric 11 with a retroreflective (this
time square) dot pattern and a distinct colour pattern (depicted by
areas A, B) which may have been preprinted before application of
the retroreflective dot areas.
[0053] FIG. 8 illustrates a breathable and/or moisture management
fabric 11 having, in addition to metallised beaded areas 14, also
areas 16 of non-metallised glass beads which, optionally, are
rendered retroreflective by having reflective particles such as
metal or mica flake 17 embedded in the adhesive layer 18 attaching
the beads to the fabric 11.
[0054] The non-metallised beads can, of course, have a colour
system which can be any of the systems that can be used for the
metallised beads. The fabric 11 may also have areas of non-aligned,
hemispherically coated retroreflective microbeads--these can be
printed on as retroreflective ink in what is by now the usual
way.
[0055] The fabric 11 may be a fire-retardant fabric such as a
Nomex.RTM. fabric or one treated with a fire retardant such as
Proban.RTM., and the adhesive systems/inks used on the fabric may
also be fire-retardant or flame resistant.
[0056] Protective clothing made of such materials, especially when
made breathable and/or capable of moisture management by
discontinuous, eg. dot or reverse dot pattern printing, are
especially beneficial since by virtue of the highly
retroreflective, aligned microbead areas, they have very good
retroreflectivity, and they can by virtue of other colouration be
given daytime conspicuity which is not compromised by relatively
inefficient areas of non-aligned microbeads which tend to give a
grey cast to the fabric in daylight conditions. Of course, as
mentioned above, such non-aligned bead areas can be incorporated
for special effects, eg. to give contrasting levels of
retroreflectivity.
[0057] FIG. 5 is a flow diagram showing the manufacturing process
for fabrics according to the invention, and FIG. 6 shows cross
sections of the materials involved at various stages.
[0058] Step 1 is to apply an adhesive layer 61 to a substrate or
carrier such as Kraft paper 62 (see FIG. 6A). A suitable adhesive
for layer 61 is a linear low density polyethylene (LLDPE). The
thickness of the adhesive layer 61 is substantially one half of the
bead diameter, the beads 63 themselves being of a substantially
uniform diameter--beads referred to as "2F2S" ie. twice fired twice
sieved, are especially appropriate.
[0059] The beads 63 may be prior-treated in various ways to ensure
good metal-to-bead adhesion, for example. Step 2 involves
scattering of the beads 63 on to the adhesive layer 61 and
levelling them to a uniform, semi-embedded monolayer by a roller
R--illustrated only diagrammatically in FIG. 6B. If desired, the
beads may be applied to the carrier in the manner described in our
prior International Application No. WO 00/54079.
[0060] In Step 3, the exposed bead surfaces are metallised in the
usual way, so that each microbead 63 now has a retroreflective
layer of aluminium 64 over half its surface (FIG. 6C). The
metallisation may be carried out selectively, e.g. according to a
predetermined pattern, so that in some areas the beads are
metallised and in other areas they are not. In this way, when
applied to the fabric, areas of dots consisting of metallised beads
and areas of dots consisting of non-metallised beads are obtained.
The non-metallised beads may be associated with colourant (e.g.
provided on the beads themselves or in the binder adhering the
beads to the fabric) and/or reflective material, such as mica or
metal (e.g. aluminium) flakes or particles, which may be
incorporated in the binder adhering the beads to the fabric. In
this way, contrasts in reflectivity and colouration may be
achieved.
[0061] In Step 4, a thin primer layer 65 is applied to the surface
of the beads 63--see FIG. 6D.
[0062] At this point, there are alternatives.
[0063] At Step 5, adhesive 70 may be applied in a pattern to the
primer layer 65, as by screen printing so as to result in pattern
areas of dots as referred to above. However, an adhesive may
instead be applied overall, and then printed in a pattern, again,
eg. of dots as by a screen printing operation, with an ink that
"kills" the adhesive. The first of these possibilities will result
in transfer of microbeads, subsequently, to the adhesive dots, to
result in a dot pattern of microbeads, the second will result in
the production of a reverse dot pattern in which the dots are free
of microbeads but are surrounded by areas covered in
microbeads.
[0064] Instead of applying adhesive 70 to the primer-covered bead
layer, adhesive may--Step 5'--be applied to a fabric to which the
beads are to be transferred. Again, the adhesive may be applied in
a dot pattern, or instead, applied overall (at least in areas
intended to be retroreflective) and overprinted with a dot pattern
of ink, to give a dot pattern or a reverse dot pattern of
retroreflective areas respectively.
[0065] The adhesive to be applied to the Kraft paper or the fabric
to be printed may be a polyamide, plastisol or polyurethane
adhesive which may cross-link on application of heat, for improved
washability of the fabric.
[0066] Bead transfer--Step 6--is effected under heat and pressure,
eg. by bringing the bead-carrying carrier 62 and fabric 11 together
between heated rollers to produce the composite illustrated in FIG.
6E. The carrier is subsequently stripped from the fabric (Step 7)
to leave the microbeads adhered by adhesive 70 to the fabric 11 in
the desired dot or reverse dot pattern (see FIG. 6F). The process
can for instance be run with a 60 inch wide fabric on a reel to
reel basis.
[0067] Except for any desired after-treatments, the fabric is now
finished though other printing, the application of retroreflective
ink printing and/or the application of non-metallised bead areas
can if desired be effected at this stage.
[0068] The Kraft paper, however, may still have copious microbead
coverage, and can be re-used, possibly three or more times,
depending on how many beads are transferred at each use, to produce
another fabric, by displacing the print pattern to utilise the
remaining microbeads. FIG. 7 shows a partially unbeaded paper with
areas 71 from which further beads may be removed in a second
transfer operation.
[0069] Prior to or after transfer of beads from the transfer paper
to the fabric, it is possible to apply coloured adhesive to the
transfer paper in areas in which the beads are absent (or removed
by transfer), to allow the production of solid areas or patterns of
coloured non-reflective adhesive to be transferred to the fabric at
the same time as bead transfer is effected.
[0070] Even when there are too few microbeads left to make further
transfer feasible, the remaining beads can be recovered as
illustrated in FIG. 9. The paper, beaded side out, is coated to
stiffen up the adhesive and run over a small radius such as roller
91, which causes the beads to pop out of their "sockets" in the
adhesive for collection and re-use in inks.
[0071] It is possible to make a double-sided retroreflective fabric
by applying adhesive to both faces of a fabric, or to two transfer
sheets, and applying two transfer sheets simultaneously to opposite
faces of the fabric. Of course, in the same way, the fabric may be
made retroreflective on one face, and otherwise printed on the
other face, in each case by transfer printing.
* * * * *