Background
[0001] In recent years, a significant industry has developed which involves the application
of customer-selected designs, messages, illustrations, and the like (referred to collectively
hereinafter as "images") to substrates through the use of heat transfer papers. The
images are transferred from the heat transfer paper to the substrate through the application
of heat and pressure, after which the release or transfer paper is removed. Typically,
a heat transfer material includes a cellulosic base sheet and an image-receptive coating
on a surface of the base sheet. The image-receptive coating usually contains one or
more thermoplastic polymeric binders, as well as, other additives to improve the transferability
and printability of the coating. For example
US 2009/280250 discloses a heat transfer material comprising an image-receptive coating which comprises
thermoplastic polyolefin wax microparticles and a thermoplastic binder.
[0002] The quality of the image formed on the image-receptive coating on the heat transfer
material directly correlates to the quality of the image formed on the final substrate
(e.g., an article of clothing). Digital electrographic toner printing (often referred
to as laser printing) is a well-known method of printing high quality images onto
a paper sheet. Another type of digital toner printing is called digital offset printing.
[0003] When utilizing a toner ink printing process, the printable surface (e.g., an image-receptive
coating of a heat transfer sheet) is specially designed to fuse with the toner ink
at the printing temperatures (e.g., typically from about 50 °C to about 120 °C but
sometimes may reach as high as about 200°C). This printable surface is designed to
attract and adhere the toner ink from the printer. However, due to this affinity for
the toner ink, the printable surface often picks up unwanted, stray toner ink from
the printer. This stray toner ink can blur the image and provide unwanted background
"noise" on the printable surface. When utilized with a heat transfer paper, any stray
toner ink on the heat transfer paper will be transferred to the substrate.
[0004] As such, a need exists for a heat transfer paper which improves the quality of an
image printed onto the image-receptive coating of a heat transfer paper.
Summary
[0005] The present invention is directed to, in one embodiment, a method of making a heat
transfer material. According to the method, a splittable layer is formed to overlie
a base sheet. An image-receptive coating is formed to overlie the splittable layer.
The image-receptive coating includes thermoplastic polystyrene microparticles, a thermoplastic
binder, and a humectant. The thermoplastic polystyrene microparticles have an average
particle size of from about 5 µm (microns) to about 80 µm (microns) and melt at temperatures
between about 90°C and about 115°C.
In an alternative embodiment thermoplastic polyester microparticles having an average
particle size of from 5µm to 80 µm and melting at temperatures between 90°C and 115°C
can be substituted for the polystyrene microparticles for use in the image receptive
coating.
[0006] A second thermoplastic microparticle (e.g., thermoplastic polyamide microparticles)
can also be included in the image-receptive coating. Alternatively, a combination
of thermoplastic polyester microparticles and thermoplastic polyamide microparticles
can be included in the image-receptive coating. The heat transfer material is then
dried. The humectant is configured to draw moisture back into the heat transfer sheet
after drying.
[0007] The present invention is also generally directed to, in another embodiment, a heat
transfer material configured for hot peel heat transfer of an image to a substrate.
Additionally, the present invention is directed to a method of transferring an image
to a substrate using the heat transfer material presently described.
[0008] Other features and aspects of the present invention are discussed in greater detail
below.
Brief Description of the Drawings
[0009] A full and enabling disclosure of the present invention, including the best mode
thereof, directed to one of ordinary skill in the art, is set forth more particularly
in the remainder of the specification, which makes reference to the appended figures
in which:
Figure 1 shows a cross-sectional view of an exemplary heat transfer sheet made in
accordance with the present invention; and
Figures 2-4 sequentially show an exemplary method of transferring an image to a substrate
using the heat transfer sheet of Fig. 1.
[0010] Repeat use of reference characters in the present specification and drawings is intended
to represent same or analogous features or elements of the invention.
Definitions
[0011] As used herein, the term "printable" is meant to include enabling the placement of
an image on a material by any means, such as by direct and offset gravure printers,
silk-screening, typewriters, laser printers, laser copiers, other toner-based printers
and copiers, dot-matrix printers, and ink jet printers, by way of illustration. Moreover,
the image composition may be any of the inks or other compositions typically used
in printing processes.
[0012] The term "toner ink" is used herein to describe an ink adapted to be fused to the
printable substrate with heat.
[0013] The term "molecular weight" generally refers to a weight-average molecular weight
unless another meaning is clear from the context or the term does not refer to a polymer.
It long has been understood and accepted that the unit for molecular weight is the
atomic mass unit, sometimes referred to as the "dalton." Consequently, units rarely
are given in current literature. In keeping with that practice, therefore, no units
are expressed herein for molecular weights.
[0014] As used herein, the term "cellulosic nonwoven web" is meant to include any web or
sheet-like material which contains at least about 50 percent by weight of cellulosic
fibers. In addition to cellulosic fibers, the web may contain other natural fibers,
synthetic fibers, or mixtures thereof. Cellulosic nonwoven webs may be prepared by
air laying or wet laying relatively short fibers to form a web or sheet. Thus, the
term includes nonwoven webs prepared from a papermaking furnish. Such furnish may
include only cellulose fibers or a mixture of cellulose fibers with other natural
fibers and/or synthetic fibers. The furnish also may contain additives and other materials,
such as fillers, e.g., clay and titanium dioxide, surfactants, antifoaming agents,
and the like, as is well known in the papermaking art.
[0015] As used herein, the term "polymer" generally includes, but is not limited to, homopolymers;
copolymers, such as, for example, block, graft, random and alternating copolymers;
and terpolymers; and blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible geometrical configurations
of the material. These configurations include, but are not limited to isotactic, syndiotactic,
and random symmetries.
Detailed Description
[0016] Reference will now be made in detail to embodiments of the invention, one or more
examples of which are provided herein. Each example is provided by way of explanation
of the invention and not meant as a limitation of the invention. For example, features
illustrated or described as part of one embodiment may be utilized with another embodiment
to yield still a further embodiment. It is intended that the present invention include
such modifications and variations as come within the scope of the appended claims.
[0017] Generally speaking, the present invention is directed to a heat transfer paper configured
to reduce the amount of stray toner on the image-receptive coating, especially when
the image is formed via a laser printer or laser copier. Although the composition
of the toner ink can vary (e.g., according to its color, the printing process utilized,
etc.), the toner ink generally adheres to the image-receptive coating at the elevated
printing temperatures. These toner printing processes result in the toner ink fusing
to the image-receptive coating, which can increase the durability of the transferred
image on the substrate. Additionally, the heat transfer paper can provide superior
color quality to transferred images as well as wash durability in that image.
[0018] In order to produce an image on a substrate, a toner ink is first applied (e.g.,
printed) onto an image-receptive coating of a heat transfer sheet to form an image.
The image printed onto the image-receptive coating is a mirror image of the image
to be transferred to the final substrate. One of ordinary skill in the art would be
able to produce and print such a mirror image, using any one of many commercially
available software picture/design programs. Due to the vast availability of these
printing processes, nearly every consumer easily can produce his or her own image
to make a coated image on a substrate. Essentially, any design, character, shape,
or other image that the user can print onto the image-receptive layer coating can
be transferred to the substrate. The image formed on the image-receptive coating of
the heat transfer sheet can be either a "positive" or "negative" image. A "positive"
image is an image that is defined by the ink applied to the image-receptive coating.
On the other hand, a "negative" image is an image that is defined by the area of the
image-receptive coating that is free of ink.
[0019] Referring to Fig. 1, an exemplary heat transfer sheet 10 is shown having a toner
ink 12 applied to its image-receptive coating 14. In Fig. 1, an image is positively
defined by the toner ink 12 on the image-receptive coating 14, with the remainder
of the surface area of the image-receptive coating 14 being substantially free of
toner ink 12. As stated, the image defined by toner ink 12 is a mirror image of the
desired coated image to be applied to the final substrate.
[0020] The image-receptive coating 14 overlies a splittable layer 16 and a base sheet 18.
In the exemplary embodiment shown, the image-receptive coating 14 is adjacent to and
directly overlies the splittable layer 16, without any intermediate layers. In turn,
the splittable layer 16 is adjacent to and directly overlies the base sheet 18, also
without any intermediate layers. However, in other embodiments, intermediate layers
may be positioned between the image-receptive coating 14, the splittable layer 16,
and/or the base sheet 18. For example, a conformable layer may be positioned between
the base sheet 18 and splittable layer 16 to facilitate the contact between the heat
transfer sheet 10 and the substrate 20 to which the image is to be transferred. An
example of a suitable conformable layer is disclosed in
U.S. Pat. No. 4,863,781 to Kronzer.
[0021] The toner ink 12 is, in one particular embodiment, printed on the image-receptive
coating 14 via the use of a laser printer or laser copier. These printing processes
typically operate at temperatures ranging from about 50° C to about 120° C, but may
sometimes be as high as 200°C, to ensure that the toner ink 12 melts and adheres to
the surface to which it is printed. The image-receptive coating 14 resists melting
at the printing temperatures to inhibit damage to the coating and to resist leaving
residual coating material on the printer/copier machinery.
[0022] After the toner ink 12 has been printed onto the image-receptive coating 14, the
heat transfer sheet 10 is positioned adjacent to a substrate 20. The heat transfer
sheet 10 is positioned such that the image-receptive coating 14 and the toner ink
12 are adjacent to the substrate 20, as shown in Fig. 2. The substrate 20 can be any
surface to which the image is to be transferred. The substrate can be a fabric cloth,
nonwoven web, film, or any other surface. Desirable substrates include, for example,
fabrics such as 100% cotton T-shirt material, and so forth.
[0023] Heat (H) and pressure (P) are then applied to the exposed base sheet 18 of the heat
transfer sheet 10 adjacent to the substrate 20. The heat (H) and pressure (P) can
be applied to the heat transfer sheet 10 via a heat press, an iron (e.g., a conventional
hand iron), etc. The heat (H) and pressure (P) can be applied to the heat transfer
sheet 10 for a time sufficient to cause the image-receptive coating 14 and the splittable
layer 16 to soften and melt. Temperatures at the transfer can be from about 150° C
or greater, such as from about 150°C to about 250°C, and can be applied for a period
of a few seconds to a few minutes (e.g., from about 5 seconds to about 5 minutes).
[0024] At the transfer temperature, both the image-receptive coating 14 and the splittable
layer 16 soften and melt. The image-receptive coating 14 softens and flows directly
onto or into the substrate 20. Once the heat (H) and pressure (P) are removed from
the heat transfer sheet 10, the base sheet 18 is removed before the heat transfer
sheet 10 can substantially cool (i.e., while the heat transfer sheet 10 is still hot).
Removing the base sheet occurs by separating the splittable layer 16. A first portion
(16A) of the splittable layer 16 remains on the base sheet 18 and is removed from
the substrate 20, while a second portion (16B) of the splittable layer 16 is transferred
to the substrate 20 along with the image-receptive coating 14. This process is an
example of a hot peelable transfer process. As used herein, the phrase "hot peelable
transfer process" refers to a process wherein one or more meltable layers is still
in a molten state when a non-transferable portion of a heat transfer sheet is removed.
Such a process allows release of the heat transfer sheet via splitting of the meltable
layer(s).
[0025] Thus, as discussed above, the image-receptive coating 14 of the present invention
does not appreciably melt and/or soften at the printing temperatures in the laser
printer and/or copier. However, the image-receptive coating 14 does melt and soften
at the transfer temperatures during the heat transfer of the image to the substrate
20.
I. Image-Receptive Coating
[0026] The image-receptive coating 14 is configured to melt and conform to the surface of
the substrate 20 to which the image is applied. In addition, the image-receptive coating
14 provides a print surface for the heat transfer sheet 10 and is formulated to minimize
feathering of the printed image and bleeding or loss of the image when the transferred
image is exposed to water.
[0027] According to one embodiment of the present invention, thermoplastic polystyrene microparticles
having a narrow melting range are present in the image-receptive coating 14. The thermoplastic
polystyrene microparticles provide a porous structure to the image-receptive coating
14 enabling better absorption of the toner ink 12 to the image-receptive coating 14.
Additionally, the image-receptive coating 14 is constructed to reduce or eliminate
the attraction of stray toner ink to the heat transfer sheet 10.
[0028] Polystyrenes are polymers that can acquire a negative charge during the printing
process. Typically, when utilizing a laser printer/copier to apply a toner ink to
a printable surface, a static charge is created on the printable surface through contact
with the various rollers utilized in the laser printer/copier. While at the printing
temperature, the toner ink is attracted to and adheres to this charged surface. The
printing surface and the toner ink then cool off quickly, drying the toner ink in
place on the printable surface. Without wishing to be bound by theory, the present
inventor believes that the thermoplastic polystyrene microparticles can quickly dissipate
any static charge that is built up in the image-receptive coating 14. The loss of
this static charge inhibits the image-receptive coating 14 from attracting any stray
toner ink from the laser printer/copier, which would otherwise be attracted to a charged
image-receptive coating 14.
[0029] It is believed that this ability to dissipate the charge created during the printing
process can be attributed to the nature of the polystyrenes to acquire a negative
static charge by attracting electrons when contact other materials. For example, according
to the Triboelectric Series, which is a list of materials showing which have a greater
tendency to become positive (give away electrons) and which have a greater tendency
to become negative (acquire electrons), polystyrene tends to attract electrons. Triboelectricity
is the physics of charge generated through friction. The triboelectric series is a
list that ranks various materials according to their tendency to gain or lose electrons.
It usually lists materials in order of decreasing tendency to charge positively (lose
electrons), and increasing tendency to charge negatively (gain electrons). Somewhere
in the middle of the list are materials that do not show strong tendency to behave
either way. Note that the tendency of a material to become positive or negative after
triboelectric charging has nothing to do with the level of conductivity (or ability
to discharge) of the material. Due to complexities involved in experiments that involve
controlled charging of materials, different researchers sometimes get different results
in determining the rank of a material in the triboelectric series. One of the reasons
for this is the multitude of factors and conditions that affect a material's tendency
to charge. However, the listing shown in Table 1, is a commonly used Triboelectric
Series (shown from the most positive to neutral to the most negative).
TABLE 1: Triboelectric Series
SURFACE MATERIAL |
CHARGE |
Human skin |
Large Positive |
Leather |
|
Rabbit's fur |
|
Acetate |
|
Glass |
|
Quartz |
|
Mica |
|
Human hair |
|
Polyamide |
|
Wool |
|
Lead |
|
Silk |
|
Aluminum |
|
Paper |
Small Positive |
Cotton |
None |
Steel |
None |
Wood |
Small Negative |
Lucite |
|
Amber |
|
Sealing wax |
|
Acrylic |
|
Polystyrene |
|
Rubber balloon |
|
Hard rubber |
|
Nickel, Copper |
|
Sulfur |
|
Brass, Silver |
|
Gold, Platinum |
|
Acetate, Rayon |
|
Synthetic rubber |
|
Polyester |
|
Styrene (Styrofoam) |
|
Orlon |
|
Polyvinylidene chloride |
|
Polyurethane |
|
Polyethylene |
|
Polypropylene |
|
Vinyl (PVC) |
|
Silicon |
|
Teflon |
|
Silicone rubber |
|
Ebonite |
Large Negative |
[0030] Polystyrene is an aromatic polymer made from the aromatic monomer styrene. Pure polystyrene
is generally a long chain hydrocarbon with every other carbon connected to a phenyl
group "Isotactic polystyrene" generally refers to an isomer of polystyrene where all
of the phenyl groups are on the same side of the hydrocarbon chain. Metallocene-catalyzed
polymerization of styrene can produce an ordered "syndiotactic polystyrene" with the
phenyl groups on alternating sides. This syndiotactic polystyrene is highly crystalline
with a melting point of about 270 °C.
[0031] "Atactic polystyrene" generally refers to an isomer of polystyrene where the phenyl
groups are randomly distributed on both sides of the hydrocarbon chain. This random
positioning prevents the polymeric chains from ever aligning with sufficient regularity
to achieve any significant crystallinity. As such, atactic polystyrene has no true
melting point and generally melts over a relatively large temperature range, such
as between about 90°C and about 115°C. This relatively large melting temperature range
allows the thermoplastic polystyrene microparticles to resist melting and flowing
at the temperatures briefly encountered during printing by the laser printer/copier,
but sufficiently melt at the transfer temperature encountered during heat transfer
of the image to the substrate. According to the present invention the thermoplastic
polystyrene microparticles melt at a temperature range between about 90°C and about
115°C. In one particular embodiment, the thermoplastic polystyrene microparticles
melt at a temperature range between about 95°C and about 105°C.
[0032] The melting point of the thermoplastic polystyrene microparticles can be influenced
by the molecular weight of the thermoplastic polystyrene microparticles, although
the melting point can be influenced by other factors. In one embodiment, the weight
average molecular weight (M
w) of the thermoplastic polystyrene polymer in the microparticles can be from about
10,000 g/mol to about 15,000 g/mol and the number average molecular weight (determined
by measuring the molecular weight of n polymer molecules, summing the weights, and
dividing by
n) can be from about 2,500 to about 10,000.
[0033] The present inventor has found that control of the particle size of the thermoplastic
polystyrene microparticles is particularly important in controlling the affinity of
the image-receptive coating 14 to unwanted stray toner ink. According to the present
invention the thermoplastic polystyrene microparticles have an average particle size
(diameter) of about 5 micrometers (microns) to about 80 µm (microns), such as from
about 15 µm (microns) to about 50 µm (microns). For example, the thermoplastic polystyrene
microparticles can be polystyrene particles having an average diameter of about 20
µm (microns) (e.g., a diameter range of about 18 µm (microns) to about 22 µm (microns))
and an average molecular weight of 12,000 g/mol, such as the polystyrene particles
available under the trade name DYNOSEED TS-20 (Microbeads AS, Skedsmokorset, Norway).
Another example of suitable thermoplastic polystyrene microparticles can be polystyrene
particles having an average diameter of about 40 µm (microns) (e.g., a diameter range
of about 38 µm (microns) to about 42 µm (microns)) and an average molecular weight
of 15,500 g/mol, such as the polystyrene particles available under the trade name
DYNOSEED TS-40 (Microbeads AS, Skedsmokorset, Norway).
[0034] The thermoplastic polystyrene microparticles can be present in an amount of from
about 10% to about 90% based on the dry weight of the image-receptive coating 14,
such as from about 25% to about 85%. In one particular embodiment, the thermoplastic
polystyrene microparticles can be present in the image-receptive coating 14 from about
30% to about 80% based on the dry weight of the image-receptive coating 14, such as
from about 35% to about 80%.
[0035] In one embodiment, another type of thermoplastic polymer microparticles can be included
in the image-receptive coating 14 along with the thermoplastic polystyrene microparticles.
Like the thermoplastic polystyrene microparticles, the second thermoplastic polymer
microparticles can provide a porous structure to the image-receptive coating 14 enabling
better absorption of the toner ink 12 into the image-receptive coating 14. The second
type of thermoplastic polymer microparticles can also add gloss, abrasion resistance,
and/or another quality to the image-receptive coating 14 transferred to the heat transfer
sheet 10. The second thermoplastic polymer microparticles can be present in an amount
of from about 10% to about 75% based on the dry weight of the image-receptive coating
14, such as from about 25% to about 50%. In one particular embodiment, the thermoplastic
polystyrene microparticles can be present in the image-receptive coating 14 from about
30% to about 45% based on the dry weight of the image-receptive coating 14, such as
from about 35% to about 40%. The second thermoplastic polymer microparticles can be
present in a dry weight percentage that is substantially equal to the thermoplastic
polystyrene microparticles.
[0036] The second thermoplastic polymer microparticles may be polyamide, polyester, polyolefin,
ethylene-vinyl acetate copolymer, or mixtures thereof, and can have an average particle
size ranging from about 2 to about 50 µm (microns), such as from about 5 to about
20 µm (microns). In one particular embodiment, the second thermoplastic polymer microparticles
are polyamide microparticles. Suitable polyamide microparticles are those 6/12 copolyamide
particles (believed to be a copolymer of a 6C diamine and a 12C diacid, sometimes
referred to as a 6/12 nylon) available commercially under the trade name Orgasol®
3501 EXD (Atofina Chemicals, Inc., Philadelphia, I.), which have an average particle
size (measured as the diameter) of 10 µm (microns) with a variation of about +/- 3
and Orgasol® 3502 EXD (Atofina Chemicals, Inc., Philadelphia, I.), which have an average
particle size (measured as the diameter) of 20 µm (microns) with a variation of about
+/- 3. Other microparticles suitable as the second thermoplastic polymer microparticles
are commercially available under the trade name PropylTex 200S (Micro Powders, Inc.,
Tarrytown, NY), which are believed to be polypropylene particles having an average
diameter of about 35 µm (microns) to about 45 µm (microns) and a maximum particle
size of 74 µm (microns).
[0037] In an alternative embodiment, thermoplastic polyester microparticles can be substituted
for the polystyrene microparticles, for use in the image-receptive coating 14 either
alone or in combination with thermoplastic polyamide microparticles, such as those
described above. According to the present invention the thermoplastic polyester microparticles
have an average particle size of from about 5 µm (microns) to about 80 µm (microns)
and melt at temperatures between about 90°C and about 115°C.
[0038] Additionally, the image-receptive coating 14 includes a thermoplastic binder. The
thermoplastic binder can act as an anchor to hold the thermoplastic polystyrene microparticles
in the image-receptive coating 14. Thus, the thermoplastic binder can provide cohesion
and mechanical integrity to the image-receptive coating 14. In general, any thermoplastic
binder may be employed which meets the criteria specified herein. Suitable thermoplastic
thermoplastic binders include, but are not limited to, polyamides, polyolefins, polyesters,
polyurethanes, poly(vinyl chloride), poly(vinyl acetate), polyethylene oxide, polyacrylates,
polystyrene, polyacrylic acid, and polymethacrylic acid. Copolymers and mixtures thereof
also can be used. As a practical matter, water-dispersible ethylene-acrylic acid copolymers
have been found to be particularly effective thermoplastic binders. The thermoplastic
binder can be present from about 5% to about 40% based on the dry weight of the image-receptive
coating 14, such as from about 10% to about 30%.
[0039] In one particular embodiment, the thermoplastic binder can be "polar" in nature.
Differences in polarity between two substances (such as a polymer and a solvent) are
directly responsible for the different degrees of-intermolecular stickiness from one
substance to another. For instance, substances that have similar polarities will generally
be soluble or miscible in each other but increasing deviations in polarity will make
solubility increasingly difficult. Without wishing to be bound by theory, it is believed
that if the binder used in the image-receptive coating 14 is more polar, the toner
ink 12 can adhere better and with more durability to the thermoplastic binder having
some degree of polarity. As such, the image-receptive coating may lose less of the
toners after several wash and dry cycles than similar coatings made with non-polar
binders.
[0040] In general, any polar thermoplastic binder can be utilized in accordance with the
present invention. In one embodiment, polymers containing carboxy groups can be utilized.
The presence of carboxy groups can readily increase the polarity of a polymer because
of the dipole created by the oxygen atom. For example, in some embodiments, carboxylated
(carboxy-containing) polyacrylates can be used as the acrylic latex binder. Also,
other carboxy-containing polymers can be used, including carboxylated nitrile-butadiene
copolymers, carboxylated styrenebutadiene copolymers, carboxylated ethylene-vinylacetate
copolymers, and carboxylated polyurethanes. Also, in some embodiments, a combination
of polar thermoplastic binders can be utilized within the transfer coating.
[0041] In one embodiment, the polar thermoplastic binder can be an acrylic latex binder.
Suitable polyacrylic latex binders can include polymethacrylates, poly(acrylic acid),
poly(methacrylic acid), and copolymers of the various acrylate and methacrylate esters
and the free acids; ethylene-acrylate copolymers; vinyl acetate-acrylate copolymers,
and the like. Suitable acrylic latex polymers that can be utilized as the thermoplastic
binder include those acrylic latexes sold under the trade name HYCAR® by Noveon, Inc.
of Cleveland, Ohio, such as HYCAR® 26684 and HYCAR® 26084.
[0042] The image-receptive coating 14 also includes a humectant configured to draw moisture
back into the image-receptive coating 14 after drying. The moisture can help preserve
the image-receptive coating 14 (along with the heat transfer sheet 10) during production
and storage. However, due to the strict melting characteristic demands of the image-receptive
coating 14, the humectant does not melt at the printing temperature, so as to avoid
any processing problems during the printing process. Thus, the humectant has a melting
point of greater than about 120°C.
[0043] The image-receptive coating 14 can, in one particular embodiment, include urea (also
known as diaminomethanal) as the humectant. Urea has a melting point of 132.7°C, which
is generally above the temperatures associated with the printing process. Urea decomposes
upon heating at temperatures higher than 132.7°C. Thus, at the transfer temperature,
the urea can decompose and form by-products, such as ammonia, oxides of nitrogen,
and carbon dioxide. This decomposition of urea at the transfer temperature acts to
remove the urea from the transferred image-receptive coating 14. This result is particularly
useful since the humectant serves no purpose after the image-receptive coating 14
is transferred to the substrate 20 and the base sheet 18 is removed.
[0044] A second humectant can also be present in the image-receptive coating 14 to facilitate
the return of moisture into the image-receptive coating 14 after drying.
[0045] In one particular embodiment, the second humectant can be a hydrophilic polymer,
such as polyethylene glycol or polypropylene glycol. However, polyethylene glycol
melts at temperatures encountered during the printing process. The amount of this
hydrophilic polymer (e.g., polyethylene glycol) included within the image-receptive
coating 14 is therefore limited. If too much of this meltable hydrophilic polymer
is included in the image-receptive coating 14, then the image-receptive coating 14
can stick to the fuser section of some laser printer/copier machines. For example,
the hydrophilic polymer can be included in an amount of less than about 3% by weight
based on the dry weight of the image-receptive coating 14, such as from about 0.01
% to about 2%.
[0046] This hydrophilic polymer, particularly polyethylene glycol, can double as a plasticizer
when included in the image-receptive coating 14. One suitable polyethylene glycol
that can be included in the image-receptive coating 14 as the second humectant, and
as a plasticizer, is available under the name Carbowax E-300 from Dow Chemical Company,
Midland, Mich.
[0047] Processing aids can also be included in the image-receptive coating 14, including,
but not limited to, thickeners (e.g., sodium polyacrylate such as Paragum 231 from
Para-Chem Southern, Inc., Simpsonville, South Carolina), dispersants, viscosity modifiers,
etc. Surfactants can also be present in the image-receptive coating 14. In one embodiment,
the surfactant can be a non-ionic surfactant, such as the non-ionic surfactant available
under the trade name Triton X100 (Dow Chemical Company, Midland, Mich.).
[0048] Additionally, pigments and other coloring agents may be present in the image-receptive
coating 14. For decoration of dark fabrics, the image-receptive coating 14 may further
include an opacifier with a particle size and density well suited for light scattering
(e.g., aluminum oxide particles, titanium oxide particles, and the like). However,
when it is desired to have a relatively clear or transparent coating, the image-receptive
coating 14 can be substantially free from pigments, opacifying agents, and other coloring
agents (e.g., free from metal particles, metalized particles, clay particles, etc.).
[0049] In one embodiment, the image-receptive coating 14 does not contain a cross-linking
agent or other catalyst that would promote crosslinking in the image-receptive coating
14, especially between the polymeric materials in the coating (i.e., the thermoplastic
polystyrene microparticles, the thermoplastic binder, the second thermoplastic microparticles,
etc.). In this regard, the melt properties of the image-receptive coating 14 can remain
substantially unchanged through the various heating and cooling processes to which
it is subjected (e.g., the printing process and the image transfer process). Thus,
the polymeric material of the image-receptive coating 14 can be substantially cross-link
free. For example, the polystyrene is not, in one particular embodiment, a copolymer
containing divinylbenzene for cross-linking the polystyrene chains. The polymeric
material can, for example, have less than about 10% of its polymeric chains crosslinked
to each other through inter-polymer chain covalent bonding, such as less than about
5%, or less than about 2%. In this embodiment, the thermoplastic binder can include
only non-crosslinking polymeric materials (e.g., a non-crosslinking acrylic).
[0050] The image-receptive coating 14 can have a thickness of from about 20,3 µm-76,2 µm
(0,8-3 mils) to ensure that the image-receptive coating 14 provides a sufficient coating
on the heat transfer sheet 10 and subsequently to the substrate 20, while a coating
thickness of from 25,4 µm-63,5 µm (about 1.0 to about 2.5 mils) is desired. However,
if the image-receptive coating 14 is too thick or stiff, it will impart too much stiffness
to the substrate 20 after it is transferred.
[0051] The image-receptive coating 14 may be formed on the heat transfer sheet 10 by known
coating techniques, such as by roll, blade, Meyer rod, and air-knife coating procedures.
The resulting heat transfer material then may be dried by means of, for example, steam-heated
drums, air impingement, radiant heating, or some combination thereof.
II. Splittable Layer
[0052] The splittable layer 16 of the heat transfer material 10 is configured to allow the
base sheet 18 to be removed (e.g., peeled away) from the substrate 20 while still
hot (i.e., a hot peel) after the application of heat (H) and pressure (P) in the transfer
process. The splittable layer 16 generally softens and melts at temperatures lower
than those causing the image-receptive coating 14 to melt. For example, the splittable
layer 16 can melt at temperatures of from about 80°C to about 130°C. The polymer can
have, in one embodiment, a melt index, as determined in accordance with ASTM Test
Method D-1238-82, of at least about 25 g/10 minutes. However, since the splittable
layer 16 is concealed within the construction of the heat transfer material 10 by
the base sheet 18 and the image-receptive coating 14, the splittable layer 16 is protected
from melting during the printing process. Additionally, the period which the heat
transfer material 10 is exposed to higher temperatures during the printing process,
as explained above, is generally too short to cause the splittable layer 16 to melt.
[0053] The splittable layer 16 can be constructed of any polymeric material that meets the
criteria above. Polymeric materials suitable for forming the splittable layer 16 include,
but are not limited to, copolymers of ethylene and acrylic acid, methacrylic acid,
vinyl acetate, ethyl acetate, or butyl acrylate. Other polymers that may be employed
include polyesters, polyamides, and polyurethanes. Waxes, plasticizers, rheology modifiers,
antioxidants, antistats, antiblocking agents, release agents, and other additives
may be included as either desired or necessary. In one particular embodiment, the
polymeric material includes a combination of ethylene-methacrylic acid copolymer (EMAA)
and ethylene-acrylic acid copolymer (EAA).
[0054] In one embodiment, the splittable layer 16 is an extruded film layer. For example,
the splittable layer 16 may be applied to the base sheet 18 with an extrusion coater
that extrudes molten polymer through a screw into a slot die. The film exits the slot
die and flows by gravity onto the base sheet 18. The resulting coated material is
passed through a nip to chill the extruded film and bond it to the underlying base
sheet 18. For less viscous polymers, the molten polymer may not form a self-supporting
film. In these cases, the material to be coated may be directed into contact with
the slot die or by using rolls to transfer the molten polymer from a bath to the heat
transfer material.
III. Base Sheet
[0055] The heat transfer material 10 of the present invention includes base sheet 18 that
acts as a backing or support layer for the heat transfer sheet 10. The base sheet
18 is flexible and has first and second surfaces, and is typically a film or a cellulosic
nonwoven web. In addition to flexibility, the base sheet 18 also provides strength
for handling, coating, sheeting, other operations associated with the manufacture
thereof, and for removal after transfer of the image-receptive coating 14 to a substrate
20. The basis weight of the base sheet 18 generally may vary, such as from about 30
to about 150 g/m
2. Suitable base sheets 18 include, but are not limited to, cellulosic nonwoven webs
and polymeric films. A number of suitable base sheets 18 are disclosed in
U.S. Pat. Nos. 5,242,739;
5,501,902; and
U.S. Pat. No. 5,798,179.
[0056] Desirably, the base sheet 18 comprises paper. A number of different types of paper
are suitable for the present invention including, but not limited to, common litho
label paper, bond paper, and latex saturated papers. In some embodiments, the base
sheet 18 will be a latex-impregnated paper such as described, for example, in
U.S. Pat. No. 5,798,179. The base sheet 18 is readily prepared by methods that are well known to those having
ordinary skill in the art.
[0057] Although the description above is directed to a hot peel heat transfer material,
the heat transfer material of the present invention could be utilized in a cold peel
material. In this embodiment, a release coating layer (not shown) is present on the
surface of the base sheet 18 that contacts the splittable layer 16 (e.g., between
the base sheet 18 and the splittable layer 16). The release coating layer separates
the transferable material (i.e., the image-receptive coating 14 and the splittable
layer 16) of the heat transfer material 10 from the non-transferable material (i.e.,
the base sheet 18). The release coating layer does not transfer to a coated substrate.
Consequently, the release coating layer may comprise any material having release characteristics,
which is also conformable when heated. Desirably, the release coating layer does not
melt or become tacky when heated, and provides release of an image bearing coating
during a hot or cold peelable transfer process.
[0058] A number of release coating layers are known to those of ordinary skill in the art,
any of which may be used in the present invention. Typically, the release coating
layer comprises a cross-linked polymer having essentially no tack at transfer temperatures
(e.g. 177° C.) and a glass transition temperature of at least about 0° C. As used
herein, the phrase "having essentially no tack at transfer temperatures" means that
the release coating layer does not stick to an overlaying layer to an extent sufficient
to adversely affect the quality of the transferred image. Suitable polymers include,
but are not limited to, silicone-containing polymers, acrylic polymers and poly(vinyl
acetate). Further, other materials having a low surface energy, such as polysiloxanes
and fluorocarbon polymers, may be used in the release coating layer, particularly
in cold peel applications. Desirably, the release coating layer comprises a cross-linked
silicone-containing polymer or a cross-linked acrylic polymer. Suitable silicone-containing
polymers include, but are not limited to, SYL-OFF® 7362, a silicone-containing polymer
available from Dow Corning Corporation (Midland, Mich.). Suitable acrylic polymers
include, but are not limited to, HYCAR® 26672, an acrylic latex available from B.F.
Goodrich, Cleveland, Ohio; MICHEM® Prime 4983, an ethylene-acrylic acid copolymer
dispersion available from Michelman Chemical Company, Cincinnati, Ohio; HYCAR® 26684,
an acrylic latex also available from B.F. Goodrich, Cleveland, Ohio; and RHOPLEX®
SP 100, an acrylic latex available from Rohm & Haas, Philadelphia, Pa.
[0059] The release coating layer may further contain additives including, but not limited
to, a cross-linking agent, a reiease-modifying additive, a curing agent, a surfactant
and a viscosity-modifying agent. Suitable cross-linking agents include, but are not
limited to, XAMA 7, an aziridine cross-linker available from B.F. Goodrich. Suitable
release-modifying additives include, but are not limited to, SYL-OFF® 7210, a release
modifier available from Dow Corning Corporation. Suitable curing agents include, but
are not limited to, SYL-OFF® 7367, a curing agent available from Dow Coming Corporation.
Suitable surfactants include, but are not limited to, TERGITOL® 15-S40, available
from Union Carbide; TRITON® X100, available from Union Carbide; and Silicone Surfactant
190, available from Dow Coming Corporation. In addition to acting as a surfactant,
Silicone Surfactant 190 also functions as a release modifier, providing improved release
characteristics, particularly in cold peel applications.
[0060] The release coating layer may have a layer thickness, which varies considerably depending
upon a number of factors including, but not limited to, the substrate to be coated,
the thickness of the splittable layer 16, the press temperature, and the press time.
Desirably, the release coating layer has a thickness, which does not restrict the
flow of the splittable layer 16 and the image-receptive coating 14. Typically, the
release coating layer has a thickness of less than about 26 µm (microns) (1 mil).
More desirably, the release coating layer has a thickness of from 1,27 µm-12,7 µm
(about 0.05 mil. to about 0.5 mil). Even more desirably, the release coating layer
has a thickness of from 2,03 µm-8,38 µm (about 0.08 mil. to about 0.33 mil).
[0061] The thickness of the release coating layer may also be described in term of a coating
weight. Desirably, the release coating layer has a dry coating weight of less than
22.5 gsm (about 6 lb./144 yd
2). More desirably, the release coating layer has a dry coating weight of from 11.3
gsm (about 3.0 lb./144 yd
2) to 1.1 gsm (about 0.3 lb./144 yd
2). Even more desirably, the release coating layer has a dry coating weight of from
7.5 gsm (about 2.0 lb./144 yd
2) to 1.9 gsm (about 0.5 lb./144 yd
2).
[0062] The present invention may be better understood with reference to the examples that
follow. Such examples, however, are not to be construed as limiting the present invention
which is defined by the appended claims. In the examples, all parts are parts by weight
unless stated otherwise.
Examples
[0063] The following materials were used in these Examples:
Hycar 26684 (Noveon, Inc., Cleveland, Ohio) is an acrylic latex polymer;
Triton X-100 (Dow Chemical Company, Midland, Mich.) is a surfactant;
Urea;
Carbowax E-300 (Dow Chemical Company, Midland, Mich.) is a polypropylene glycol having
an average molecular weight of 300;
Paragum 231 (Para-Chem Southern, Inc., Simpsonville, S.C.) is sodium polyacrylate
useful as a thickener.
Example 1:
[0064] A base paper (10,88 kg (24 lb.) super smooth base paper available under the trade
name Classic Crest® from Neenah Paper, Inc., Alpharetta, GA) was first coated with
an acrylic splitting layer by extruded 33,02 µm (1.3 mils) EMAA (ethylene-methacrylic
acid) and 12,7 µm (0.5 mils) of EAA (ethylene-acrylic acid) onto the base paper. Then,
an image-receptive coating was applied to the splitting layer. The image-receptive
coating was applied in an amount of 2.5 pounds per ream (144 yards
2), which is about 9.4 gsm, using a Myer rod. The coating was applied as an aqueous
dispersion/mixture and then dried to remove the water.
[0065] The following dispersion:
|
% |
Dry Parts |
% Dry Weight |
Water |
|
|
|
Triton X-100 |
33 |
5 |
4.8 |
Dynoseeds TS-20 |
100 |
100 |
95.2 |
was used to make the image-receptive coating according to the formula:
|
% |
Dry Parts |
% dry wt. |
Water |
|
|
|
Particle Dispersion |
25 |
105 |
77.9 |
Hycar 26684 |
48.9 |
23 |
17.1 |
Carbowax E-300 |
100 |
1.75 |
1.3 |
Urea |
22 |
3.5 |
2.6 |
Paragum 231 |
13.8 |
1.5 |
1.1 |
[0066] The resulting coated sheets were printed using four different color laser printers
(Brother HL-4040CN, Minolta 2300, Okidata C5150, Hewlett Packard 3600) with each yielding
a clean print.
Example 2:
[0067] Different image-receptive coatings were prepared and then applied to the splitting
layer of a base paper as described above in Example 1. The compositions of each image-receptive
coating tested were essentially consistent, except for the type of particles included
in the coatings (except where noted). Table 2 shows the types of particles used in
each sample image receptive coating.
Table 2
SAMPLE |
polyamide 10 µm micron
Orgasol 3501 |
polyamide 20 µm micron
Orgasol 3502 |
polystyrene 10 µm micron
Dynoseed TS-10 |
polystyrene 20 µm micron
Dynoseed TS-20 |
polystyrene 40 µm micron
Dynoseed TS-40 |
polystyrene 80 µm micron
Dynoseed TS-80 |
polyester 0-35 µm micron
Griltex 6E |
polyester 0-75 µm micron
Griltex 6E |
A |
75% |
|
|
25% |
|
|
|
|
B |
50% |
|
|
50% |
|
|
|
|
C |
25% |
|
|
75% |
|
|
|
|
D |
|
|
|
100% |
|
|
|
|
E |
75% |
|
25% |
|
|
|
|
|
F |
50% |
|
50% |
|
|
|
|
|
G |
25% |
|
75% |
|
|
|
|
|
H |
|
|
100% |
|
|
|
|
|
I |
|
|
100% |
|
|
|
|
|
K |
75% |
|
|
|
25% |
|
|
|
L |
50% |
|
|
|
50% |
|
|
|
M |
25% |
|
|
|
75% |
|
|
|
N |
|
|
|
|
100% |
|
|
|
O |
90% |
|
|
|
|
10% |
|
|
P |
75% |
|
|
|
|
25% |
|
|
Q |
|
75% |
|
|
25% |
|
|
|
R |
|
50% |
|
|
50% |
|
|
|
S |
|
50% |
|
50% |
|
|
|
|
T |
100% |
|
|
|
|
|
|
|
U |
|
|
|
100% |
|
|
|
|
V |
|
100% |
|
|
|
|
|
|
W |
|
|
|
|
|
|
|
100% |
X |
50% |
|
|
|
|
|
|
50% |
Y |
75% |
|
|
|
|
|
|
25% |
Z |
90% |
|
|
|
|
|
|
10% |
AA |
|
|
|
|
|
|
100% |
|
BB |
50% |
|
|
|
|
|
50% |
|
CC |
75% |
|
|
|
|
|
25% |
|
DD |
90% |
|
|
|
|
|
10% |
|
[0068] The particles were included in the coating as a dispersion, created by mixing the
particles with water and a surfactant (Triton X-100 available from Dow Chemical Company,
Midland, Mich.), as shown above in Example 1 (i.e., 5 dry parts Triton X-100 to 100
dry parts particles). In addition to the particle dispersions, each coating contained
an acrylic latex polymer (Hycar 26684 available from Noveon, Inc., Cleveland, Ohio),
a propylene glycol having an average molecular weight of 300 (Carbowax E-300 available
from Dow Chemical Company, Midland, Mich.), sodium polyacrylate useful as a thickener
(Paragum 231 available from Para-Chem Southern, Inc., Simpsonville, S.C.), and urea
as shown above in Example 1 (except where noted).
[0069] In the samples shown in Table 2, Sample U is identical to Sample D except that Sample
U did not include Carbowax E300, resulting in the peel force for Sample U being siightiy
higher.
[0070] After printing, the printed sheets were used to transfer an image to a cloth (Hanes
® Beefy-T 100% cotton t-shirt). Results are shown in Table 3. All heat transfers in
these examples were hot peel transfers as described above. Printing was performed
using the Okidata C5150 laser printer.
[0071] The Sheffield smoothness of the coated sheet increases in value as the roughness
increases.
[0072] Wash Color refers to how well the transfer on fabric retained color following 5 wash
cycles. The wash color was rated on a scale of 1 - 4, with 4 being the best and 1
the worst.
[0073] Hunter L refers to a color meter machine test that assigns a value on the level of
whiteness of the transfer. To that end, an area of each printed image was purposely
left blank so that it could be used for doing a Hunter test. In theory, the more scattered
toner attracted to the sheet during printing, the less white the final transfer will
be - resulting in a less clean transfer. The higher the Hunter L value, the cleaner
the transfer. Table 3 has a column for how the transfer looks (after it is applied
to the cloth) and another column on the table for how the printed sheet looks before
transfer. For the heat transfer, how the transfer on the fabric looks is more important
since this is the end product. The peel force was measured on a scale of 1-5 as perceived
by the end user. Color densisty was determined using an X-Rite Specrodensitometer
and color 100% cyan color block and reported as Response T (US standard) visual density.
Table 3
SAMPLE |
Transfer Hunter L |
Perceived Peel Force |
Sheffield Smoothness |
Print Hunter L |
Transfer Color Visual DenT |
Wash Color |
Wash Color Visual DenT |
A |
89 |
2 |
60 |
93 |
0.90 |
4 |
0.87 |
B |
91 |
3 |
100 |
94 |
0.91 |
3 |
0.85 |
C |
92 |
2 |
120 - 130 |
94 |
0.95 |
2 |
0.82 |
D |
94 |
2 |
175 |
94 |
0.91 |
2 |
0.81 |
E |
88 |
4 |
35 - 40 |
92 |
1.01 |
4 |
0.93 |
F |
89 |
3 |
40 - 45 |
92 |
1.00 |
4 |
0.91 |
G |
91 |
3 |
60 - 75 |
93 |
0.97 |
3 |
0.86 |
H |
93 |
2 |
125 - 135 |
94 |
0.96 |
3 |
0.84 |
I |
92 |
2 |
72 - 75 |
93 |
0.95 |
2 |
0.82 |
K |
94 |
2 |
290 - 320 |
96 |
0.90 |
3 |
0.84 |
L |
95 |
3 |
370 |
96 |
0.86 |
3 |
0.84 |
M |
95 |
4 |
380 - 400 |
96 |
0.86 |
2 |
0.81 |
N |
94 |
5 |
380 - 400 |
95 |
0.80 |
1 |
0.75 |
O |
95 |
5 |
400 + |
96 |
0.77 |
1 |
0.74 |
P |
95 |
5 |
400 + |
96 |
0.78 |
1 |
0.66 |
Q |
94 |
5 |
350 |
95 |
0.95 |
4 |
0.87 |
R |
95 |
3 |
380 |
95 |
0.88 |
3 |
0.85 |
S |
91 |
3 |
135 - 140 |
93 |
0.96 |
4 |
0.88 |
T |
90 |
4 |
30 |
93 |
0.93 |
4 |
0.88 |
U |
94 |
3 |
175 |
94 |
0.96 |
2 |
0.82 |
V |
90 |
5 |
120 - 130 |
93 |
0.96 |
4 |
0.90 |
W |
95 |
3 |
400 + |
94 |
0.82 |
1 |
0.79 |
X |
94 |
3 |
360 |
95 |
0.86 |
3 |
0.85 |
Y |
94 |
3 |
250 - 270 |
95 |
0.86 |
3 |
0.86 |
Z |
91 |
4 |
80 - 110 |
93 |
0.87 |
3 |
0.85 |
AA |
94 |
3 |
330 |
94 |
0.85 |
2 |
0.83 |
BB |
92 |
3 |
150 - 160 |
94 |
0.89 |
3 |
0.86 |
CC |
91 |
3 |
85 - 95 |
94 |
0.87 |
3 |
0.86 |
DD |
90 |
4 |
50 - 65 |
93 |
0.91 |
3 |
0.85 |
[0074] These and other modifications and variations to the present invention may be practiced
by those of ordinary skill in the art, without departing from the scope of the present
invention, which is defined in the appended claims. In addition, it should be understood
the aspects of the various embodiments may be interchanged both in whole or in part.
Furthermore, those of ordinary skill in the art will appreciate that the foregoing
description is by way of example only, and is not intended to limit the invention
so further described in the appended claims.
1. A method of making a heat transfer material, the method comprising:
forming a splittable layer overlying a base sheet;
forming an image-receptive coating overlying the splittable layer to form the heat
transfer material, wherein the image-receptive coating comprises thermoplastic polystyrene
microparticles, a thermoplastic binder, and a humectant, wherein the thermoplastic
polystyrene microparticles have an average particle size of from 5 µm (microns) to
80 µm (microns) and melt at temperatures between 90°C and 115°C; and
drying the heat transfer material, wherein the humectant is configured to draw moisture
back into the heat transfer sheet after drying.
2. The method as in claim 1, wherein the thermoplastic polystyrene microparticles melt
at temperatures between 95°C and 105 °C.
3. The method as in any preceding claim, wherein the thermoplastic polystyrene microparticles
have an average particle size of from 38 µm (microns) to 42 µm (microns) or from 18
µm (microns) to 22 µm (microns).
4. The method as in any preceding claim, wherein the image-receptive coating further
comprises a plurality of second thermoplastic polymer microparticles having an average
particle size of from 2 µm (microns) to 50 µm (microns).
5. The method as in claim 4, wherein the image-receptive coating comprises the thermoplastic
polystyrene microparticles in an amount from 10% to 75% by weight based on the dry
weight of the image-receptive coating, and wherein the image-receptive coating comprises
the second thermoplastic polymer microparticles in an amount from 10% to 75% by weight
based on the dry weight of the image-receptive coating.
6. The method as in claim 4 or 5, wherein the second thermoplastic polymer microparticles
comprise polyamide microparticles.
7. The method as in any preceding claim, wherein the splittable layer directly overlies
the base sheet, and wherein the image-receptive coating directly overlies the splittable
layer.
8. The method as in any preceding claim, wherein the splittable layer is melt extruded
directly onto the base sheet, wherein the splittable layer comprises a polymeric material
that melts at temperatures between 80 °C and 130 °C.
9. A method of making a heat transfer material, the method comprising:
forming a splittable layer overlying a base sheet;
forming an image-receptive coating overlying the splittable layer to form the heat
transfer material, wherein the image-receptive coating comprises thermoplastic polyester
microparticles, a thermoplastic binder, and a humectant, wherein the thermoplastic
polyester microparticles have an average particle size of from 5 µm (microns) to 80
µm (microns) and melt at temperatures between 90°C and 115°C; and
drying the heat transfer material, wherein the humectant is configured to draw moisture
back into the heat transfer sheet after drying.
10. The method of claim 9, wherein the image-receptive coating further comprises thermoplastic
polyamide microparticles, and wherein the thermoplastic polyamide microparticles have
an average particle size of from 2 µm (microns) to 50 µm (microns).
11. The method as in any preceding claim, wherein the humectant comprises urea.
12. The method as in any preceding claim, wherein the image-receptive coating is substantially
free from a cross-linking agent.
13. The method as in any preceding claim, wherein the image-receptive coating further
comprises a hydrophilic polymer present in the image-receptive coating from a positive
amount to 3% by weight based on the dry weight of the image-receptive coating.
14. A heat transfer material configured for hot peel heat transfer of an image to a substrate,
the heat transfer material being formed according to the method of any preceding claim.
15. A method of transferring an image to a substrate, the method comprising:
printing toner ink onto the image-receptive coating of the heat transfer material
of claim 14 to form an image;
positioning the heat transfer material adjacent the substrate, wherein the image-receptive
coating contacts the substrate;
heating the heat transfer material to a temperature of 150°C to 250°C under a pressure
force; and
peeling the base sheet from the substrate while the heat transfer material is still
warm.
1. Verfahren zum Herstellen eines Thermotransfermaterials, wobei das Verfahren umfasst:
Ausbilden einer abspaltbaren Schicht, die über einer Grundbahn liegt;
Ausbilden einer Abbild-aufnehmenden Beschichtung, die über der abspaltbaren Schicht
liegt, um das Thermotransfermaterial zu bilden, wobei die Abbild-aufnehmende Beschichtung
thermoplastische Polystyrol-Mikroteilchen, ein thermoplastisches Bindemittel und ein
Feuchthaltemittel umfasst, wobei die thermoplastischen Polystyrol-Mikroteilchen eine
durchschnittliche Teilchengröße von 5 µm (Mikrometern) bis 80 µm (Mikrometern) aufweisen
und bei Temperaturen zwischen 90 °C und 115 °C schmelzen; und
Trocknen des Thermotransfermaterials, wobei das Feuchthaltemittel ausgebildet ist,
nach dem Trocknen Feuchtigkeit zurück in die Thermotransferbahn zu ziehen.
2. Verfahren nach Anspruch 1, wobei die thermoplastischen Polystyrol-Mikroteilchen bei
Temperaturen zwischen 95 °C und 105 °C schmelzen.
3. Verfahren nach einem beliebigen vorangehenden Anspruch, wobei die thermoplastischen
Polystyrol-Mikroteilchen eine durchschnittliche Teilchengröße von 38 µm (Mikrometern)
bis 42 µm (Mikrometern) oder von 18 µm (Mikrometern) bis 22 µm (Mikrometern) aufweisen.
4. Verfahren nach einem beliebigen vorangehenden Anspruch, wobei die Abbild-aufnehmende
Beschichtung weiter eine Vielzahl zweiter thermoplastischer Polymer-Mikroteilchen
mit einer durchschnittlichen Teilchengröße von 2 µm (Mikrometern) bis 50 µm (Mikrometern)
umfasst.
5. Verfahren nach Anspruch 4, wobei die Abbild-aufnehmende Beschichtung die thermoplastischen
Polystyrol-Mikroteilchen in einer Menge von 10 bis 75 Gew.-% auf Grundlage des Trockengewichts
der Abbild-aufnehmenden Beschichtung umfasst, und wobei die Abbild-aufnehmende Beschichtung
die zweiten thermoplastischen Polymer-Mikroteilchen in einer Menge von 10 bis 75 Gew.-%
auf Grundlage des Trockengewichts der Abbild-aufnehmenden Beschichtung umfasst.
6. Verfahren nach Anspruch 4 oder 5, wobei die zweiten thermoplastischen Polymer-Mikroteilchen
Polyamid-Mikroteilchen umfassen.
7. Verfahren nach einem beliebigen vorangehenden Anspruch, wobei die abspaltbare Schicht
direkt über der Grundbahn liegt, und wobei die Abbild-aufnehmende Beschichtung direkt
über der abspaltbaren Schicht liegt.
8. Verfahren nach einem beliebigen vorangehenden Anspruch, wobei die abspaltbare Schicht
direkt auf die Grundbahn schmelzextrudiert wird, wobei die abspaltbare Schicht ein
Polymermaterial umfasst, das bei Temperaturen zwischen 80 °C und 130 °C schmilzt.
9. Verfahren zum Herstellen eines Thermotransfermaterials, wobei das Verfahren umfasst:
Ausbilden einer abspaltbaren Schicht, die über einer Grundbahn liegt;
Ausbilden einer Abbild-aufnehmenden Beschichtung, die über der abspaltbaren Schicht
liegt, um das Thermotransfermaterial zu bilden, wobei die Abbild-aufnehmende Beschichtung
thermoplastische Polyester-Mikroteilchen, ein thermoplastisches Bindemittel und ein
Feuchthaltemittel umfasst, wobei die thermoplastischen Polyester-Mikroteilchen eine
durchschnittliche Teilchengröße von 5 µm (Mikrometern) bis 80 µm (Mikrometern) aufweisen
und bei Temperaturen zwischen 90 °C und 115 °C schmelzen; und
Trocknen des Thermotransfermaterials, wobei das Feuchthaltemittel ausgestaltet ist,
nach dem Trocknen Feuchtigkeit zurück in die Thermotransferbahn zu ziehen.
10. Verfahren nach Anspruch 9, wobei die Abbild-aufnehmende Beschichtung weiter thermoplastische
Polyamid-Mikroteilchen umfasst, und wobei die thermoplastischen Polyamid-Mikroteilchen
eine durchschnittliche Teilchengröße von 2 µm (Mikrometern) bis 50 µm (Mikrometern)
aufweisen.
11. Verfahren nach einem beliebigen vorangehenden Anspruch, wobei das Feuchthaltemittel
Harnstoff umfasst.
12. Verfahren nach einem beliebigen vorangehenden Anspruch, wobei die Abbild-aufnehmende
Beschichtung im Wesentlichen frei von einem Vernetzungsmittel ist.
13. Verfahren nach einem beliebigen vorangehenden Anspruch, wobei die Abbild-aufnehmende
Beschichtung ein hydrophiles Polymer umfasst, das in der Abbild-aufnehmenden Beschichtung
von einer nachweisbaren Menge bis zu 3 Gew.-% auf Grundlage des Trockengewichts der
Bild-aufnehmenden Beschichtung vorhanden ist.
14. Thermotransfermaterial, ausgestaltet für Heißablösungs-Thermotransfer eines Abbilds
auf ein Substrat, wobei das Thermotransfermaterial gemäß dem Verfahren nach einem
beliebigen vorangehenden Anspruch ausgebildet ist.
15. Verfahren zum Übertragen eines Bildes auf ein Substrat, wobei das Verfahren umfasst:
Drucken von Tonertinte auf die Abbild-aufnehmenden Beschichtung des Thermotransfermaterials
nach Anspruch 14, um ein Abbild zu bilden;
Positionieren des Thermotransfermaterials benachbart zum Substrat, wobei die Abbild-aufnehmende
Beschichtung das Substrat berührt;
Erwärmen des Thermotransfermaterials auf eine Temperatur von 150 °C bis 250 °C unter
einer Andruckkraft; und
Ablösen der Grundbahn von dem Substrat, während das Thermotransfermaterial noch warm
ist.
1. Méthode pour fabriquer un matériau de transfert de chaleur, la méthode comprenant
les étapes suivantes :
former une couche divisible susjacente à une feuille de base ;
former un revêtement réceptif d'image susjacent à la couche divisible pour former
le matériau de transfert de chaleur, dans laquelle le revêtement récepteur d'image
comprend des microparticules de polystyrène thermoplastique, un liant thermoplastique
et un humectant, dans laquelle les microparticules de polystyrène thermoplastique
ont une dimension de particule moyenne de 5 µm (microns) à 80 µm (microns) et fondent
à des températures situées entre 90°C et 115°C ; et
sécher le matériau de transfert de chaleur, dans laquelle l'humectant est configuré
pour attirer l'humidité dans la feuille de transfert de chaleur après le séchage.
2. Méthode selon la revendication 1, dans laquelle les microparticules de polystyrène
thermoplastique fondent à des températures situées entre 95°C et 105°C.
3. Méthode selon l'une des revendications précédentes, dans laquelle les microparticules
de polystyrène thermoplastique ont une dimension de particule moyenne de 38 µm (microns)
à 42 µm (microns) ou de 18 µm (microns) à 22 µm (microns).
4. Méthode selon l'une des revendications précédentes, dans laquelle le revêtement réceptif
d'image comprend en outre une multitude de secondes microparticules de polymère thermoplastique
possédant une dimension de particules moyenne de 2 µm (microns) à 50 µm (microns).
5. Méthode selon la revendication 4, dans laquelle le revêtement réceptif d'image contient
les microparticules de polystyrène thermoplastique en une quantité de 10% à 75% du
poids sur la base du poids à sec du revêtement réceptif d'image, et dans laquelle
le revêtement réceptif d'image contient les secondes microparticules de polymère thermoplastique
en une quantité de 10% à 75% du poids sur la base du poids à sec du revêtement réceptif
d'image.
6. Méthode selon la revendication 4 ou 5, dans laquelle les secondes microparticules
de polymère thermoplastique contiennent des microparticules polyamides.
7. Méthode selon l'une des revendications précédentes, dans laquelle la couche divisible
est directement susjacente à la feuille de base, et dans laquelle le revêtement réceptif
d'image est directement susjacent à la couche divisible.
8. Méthode selon l'une des revendications précédentes, dans laquelle la couche divisible
est appliquée par extrusion de matière fondue directement sur la feuille de base,
dans laquelle la couche divisible contient une matière polymérique qui fond à des
températures situées entre 80°C et 130°C.
9. Méthode pour fabriquer un matériau de transfert de chaleur, la méthode comprenant
les étapes suivantes :
former une couche divisible susjacente à une feuille de base ;
former un revêtement réceptif d'image susjacent à la couche divisible pour former
le matériau de transfert de chaleur, dans laquelle le revêtement récepteur d'image
comprend des microparticules de polyester thermoplastique, un liant thermoplastique
et un humectant, dans laquelle les microparticules de polyester thermoplastique ont
une dimension de particule moyenne de 5 µm (microns) à 80 µm (microns) et fondent
à des températures situées entre 90°C et 115°C ; et
sécher le matériau de transfert de chaleur, dans laquelle l'humectant est configuré
pour attirer l'humidité dans la feuille de transfert de chaleur après le séchage.
10. Méthode selon la revendication 9, dans laquelle le revêtement réceptif d'image comprend
en outre des microparticules de polyamide thermoplastique, et dans laquelle les microparticules
de polyamide thermoplastique ont une dimension de particule moyenne de 2 µm (microns)
à 50 µm (microns).
11. Méthode selon l'une des revendications précédentes, dans laquelle l'humectant contient
de l'urée.
12. Méthode selon l'une des revendications précédentes, dans le revêtement réceptif d'image
est substantiellement exempt d'agent de réticulation.
13. Méthode selon l'une des revendications précédentes, dans laquelle le revêtement réceptif
d'image contient en outre un polymère hydrophile présent dans le revêtement réceptif
d'image à partir d'une quantité positive à 3% du poids sur la base du poids à sec
du revêtement réceptif d'image.
14. Matériau de transfert de chaleur configuré pour le transfert de chaleur par exfoliation
à chaud d'une image sur un substrat, le matériau de transfert de chaleur étant formé
selon la méthode selon l'une des revendications précédentes.
15. Méthode pour transférer une image sur un substrat, la méthode comprenant les étapes
suivantes :
imprimer de l'encre sur le revêtement réceptif d'image du matériau de transfert de
chaleur selon la revendication 14 pour former une image ;
positionner le matériau de transfert de chaleur de manière adjacente au substrat,
dans laquelle le revêtement réceptif d'image est en contact avec le substrat ;
chauffer le matériau de transfert de chaleur à une température de 150°C à 250 °C sous
une force de pression ; et
exfolier la feuille de base depuis le substrat alors que le matériau de transfert
de chaleur est encore chaud.