CA1273851A - Heat transferable laminate - Google Patents
Heat transferable laminateInfo
- Publication number
- CA1273851A CA1273851A CA000492960A CA492960A CA1273851A CA 1273851 A CA1273851 A CA 1273851A CA 000492960 A CA000492960 A CA 000492960A CA 492960 A CA492960 A CA 492960A CA 1273851 A CA1273851 A CA 1273851A
- Authority
- CA
- Canada
- Prior art keywords
- wax
- release layer
- layer
- heat
- heat transferable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Laminated Bodies (AREA)
- Adhesives Or Adhesive Processes (AREA)
- Thermal Transfer Or Thermal Recording In General (AREA)
Abstract
HEAT TRANSFERABLE LAMINATE
ABSTRACT OF THE DISCLOSURE
An improved release coating for heat tranferable laminates wherein an ink design layer is transferred from a carrier web onto an article such as a plastic or glass container upon application of heat and pressure. The improved release coating transfers with the ink design layer and forms an optically clear protective coating over the transferred ink design layer. The transferred release coating upon resolidification has an exceedingly high optical clarity, with no hazing, spotting, or halo discernible over the transferred ink design layer. The improved release coating incorporates a tackifying resin in a wax base. The wax base includes a montan wax and a crystalline wax such as paraffin wax. The wax base may also include a microcrystalline wax component. The tackifying resin is a transparent hydrogenated hydrocarbon resin.
ABSTRACT OF THE DISCLOSURE
An improved release coating for heat tranferable laminates wherein an ink design layer is transferred from a carrier web onto an article such as a plastic or glass container upon application of heat and pressure. The improved release coating transfers with the ink design layer and forms an optically clear protective coating over the transferred ink design layer. The transferred release coating upon resolidification has an exceedingly high optical clarity, with no hazing, spotting, or halo discernible over the transferred ink design layer. The improved release coating incorporates a tackifying resin in a wax base. The wax base includes a montan wax and a crystalline wax such as paraffin wax. The wax base may also include a microcrystalline wax component. The tackifying resin is a transparent hydrogenated hydrocarbon resin.
Description
127~851 }I¢Al` T~ANS~A~LE l~MI~Ar~
~ACKG~OUND OF TIS~ INV~NTION
1. r~ield Or tlle Invelltlon:
The present inventlon relates to a heat transferable label and lmproved release composltlon thereror.
~ACKG~OUND OF TIS~ INV~NTION
1. r~ield Or tlle Invelltlon:
The present inventlon relates to a heat transferable label and lmproved release composltlon thereror.
2. Ve~crlptiotl of the ~rior Art:
Prlor art l~eat transrerable labels ror imprintlng designs onto an artlcle typically lnvolve decorative lamlnates conslstlng of a paper base sheet or web coated witi~ a wax or polymeric release layer over whlcll a design i8 lmprlnted in ink.
U.S. Patent 3,616,015 i8 illustrative of the prior art. ln U.S. Patent 3,616,015 a label carrying web such as a paper sheet lncludes a heat transrerable label composed Or a wax release layer afflxed to a surface Or tlle paper sl)eet a~d an lnk deslgn layer superlmposed onto the wax release layer. In tlle heat transfer labelling process for lmprlntlng deslgtls onto artlcles, tlle label carrylng web 18 subJected to heat and the lamlrlate 19 pre~sed onto an artlcle wlth the ink deslgn layer nnaking dlrect contact with tlle article. As the web or paper ~heet 19 subJected to heat, tlle wax layer beglns to melt 80 that the paper sheet can be releaaed froln tl~e wax layer. Arter transrer Or tlle deslgn to the artlcle, tl)e paper sheet 1~ lmmedlately removed, leavlng the deslgn rirmly arrlxed to tlle surrace with the wax layer exposed to the envIronment. The wax release layer should not only permlt release Or the transferable label rrom the web upon appllcatlon Or heat to t!le web but al80 form a clear proteatlve layer over the transrerred lnk deslen.
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~Z73851 This commonly assigned patent discloses a wax release coating containing a modified montan wax which has been oxidized, esterified, and partially saponified. In order to attain improved clarity of the transferred ink design the transferred wax coating over the ink design is subjected to additional heat processing after the label has been transferred onto an article. The additional processing involves postflaming, wherein the transferred wax coating is subjected to jets of high temperature gas either as direct gas flame or as hot air jets at temperatures of about 300F
to 400F for a period of time sufficient to remelt the wax coating without substantially heating the bottle. Upon cooling of the remelted wax coating through use of ambient or forced cooled air, the cooled wax layer solidifies to form a clear, smooth protective coating over the transferred ink design. Although the heat transferable label and process disclosed in U.S. Patent 3,616,015 represents an improvement over prior heat transferable labels, they are best suited to decoration of plastic articles which are not transparent.
Although the heat transferable label disclosed in this reference may be utilized for decorating a wide variety of different plastics, there can be a degree of hazing or halo noticeable over the transferred label when the transfer is made onto clear plastic materials, despite use of postflaming.
U.S. patent 2,990,311 discloses a heat transferable decal having a release transfer layer composed of a mixture of a crystalline wax and a synthetic thermoplastic film-forming resin, principally an organic linear thermoplastic film-forming resin which is substantially , , ' ' ' . ' .
385~
water insoluble. The d~gree Or compatiblllty Or the re31n and wax is controlled through selection and ratlo of the components to glve heat transfers of either the hot peel or cold peel type. In the hot peel transfer, the decal wlll adhere and release from the backlng only lmmedlately after appllcatlon whlle the decal 18 stlll hot. In the cold peel transfer the transferred decal wlll adhere to the recelvlng surface when hot but will only release and tran~fer by peellng away the backlng arter the transfer ha~ cooled. In elther type Or transrer~ thls rererence teache~ that reslns and waxes (the latter belng used for the relea~e layer) should be mutually lncompatlble or lnsoluble at temperatures below the meltlng temperature Or the wax such that the molten wax, upon coollng, wlll actually arystalllze separately and dlstlnctly rrom the re~ln. The resins are llnear thermoplastlc fllm-forming reslns deflned as essentlally solvent-soluble, sortened by heat and to lnvolve only a mlnor amount or no cross-linkage.
Sultable reslns speclrlcally dlsclosed are polyvlnyl acetate, polyethyl a¢rylate, polymethyl acrylate, polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, styrenebutadlene, acrylonltrlle-butadlene, polychloroprene rubbers, polyvlnyl butyral, ethyl cellulose, and polyvlnyl acetate vlnyl stearate copolymer (col. 5, 1. 38-44). The reference teaches that the wax ¢omponent should be a materlal whlch derlves lts crystalllnlty malnly from the presence Or lohg hydrocarbon chalns and should melt over a relatlvely narrow range between the temperatures Or about 50C to 110C. The penetrometer hardness value (ASTM D5-52) when tested wlth ; 100 grams for 5 seaonds at 28C should be below about , , ~2738Sl 15 . Specific waxes disclosed as suitable are beeswax, candelilla wax, carnauba wax, hydrogenated castor oil, montan wax, paraffin wax, low molecular weight polyethylene, oxidized microcrystalline wax, and hard wax or derivatives thereof obtained from the Fischer Tropsch synthesis.
(co.5,1.45-56). This references does not disclose applicant's formulation for the release layer nor does it contemplate the advantages which applicant has derived from such formulation.
U.S. patent 2,862,832 discloses a heat transferable decal having a release layer composed of an oxidized wax. The disclosure is directed principally to defining the type of wax found to provide suitable release of the decal from the carrier web upon application of heat. The wax disclosed in this reference is an oxidized wax obtained as the reaction product of the oxidation of hard, high melting, aliphatic, hydrocarbon waxes. The oxidized waxes are defined as the oxidation products of both natural and synthetic hydrocarbon waxes such as petroleum waxes, low molecular weight polyethylene and waxes obtained from the Fischer-Tropsch synthesis. Suitable wax may include oxidized microcrystalline wax or the esterification product of an oxidized hydrocarbon wax. The oxidized waxes are disclosed as those having melting points between about 50C and 110C, saponification values between about 25 and 100, acid values between about 5 and 40, and penetrometer hardness (ASTM D5-52) below about 51 as measured with 100 grams for 5 seconds at 25C.
Although this reference mentions that minor amounts of certain additives such as fillers and resins may be added to ~f :
~ .
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.
~738Sl the oxidized wax, the invention is clearly concerned with the use of wax as the essential component and designation of specific wax types found to give advantageous results. This reference does not disclose applicant's principal additives or applicant's combined formulation nor does it recognize or contemplate the advantages obtained from such formulation.
U.S. Patent 3,616,176 discloses a heat transfer laminate of a type related to that disclosed in U.S. Patent 3,616,015.
In U.S. Patent 3,616,176 the laminate is composed of a base sheet, with a polyamide layer covering the base sheet and a decorative ink layer covering the polyamide layer.
Sufficient heat is applied to the laminate to heat the polyamide layer at or above a softening point, and the laminate is then pressed onto the surface of an article with the decorative ink layer coming into direct contact. Upon withdrawal of the heat source, the polyamide layer cools to a temperature below the softening point and the base sheet is removed. The decorative layer becomes fused or heat sealed to the article. The polyamide layer in the disclosure functions as a release coating which allows transfer of the decorative layer onto an article and upon cooling serves as a protective coating layer over the transferred decorative layer. The use of a polyamide release coating has the principal disadvantage in that there is a significant tendency for the polyamide to form a noticeable halo around the transferred decorative layer. Also the polyamide layer even when sub~ected to additional processing such as post-flaming does not form sufficiently clear coating that would aesthetically permit heat transfer labelling onto clear articles or bottles.
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U.S. patent application Serial No. 130,303, commonly assigned with the present application, discloses a heat transfer label of the type illustrated in U.S. patent 3,616,015. In another form of heat transfer label developed by the Applicant, a carrier member (base sheet) is overcoated in designated regions with a release layer and an ink design layer. Optionally, a barrier layer is included between the release layer and the ink layer. The release layer is typically composed of a polymerization product of a diamine with the dimer of a fatty acid. In order to reduce the halo effect of the transferred release layer over the ink design layer, the release layer is contoured in a particular manner. To further reduce the halo effect, this reference teaches that the optional barrier layer included between the release layer and ink layer, be formed of an aromatic acid-based polyester covering and overlapping the release layer by a margin.
Applicant's U.S. patent No. 4,426,422 also discloses a heat transfer label of the type illustrated in U.S. Patent
Prlor art l~eat transrerable labels ror imprintlng designs onto an artlcle typically lnvolve decorative lamlnates conslstlng of a paper base sheet or web coated witi~ a wax or polymeric release layer over whlcll a design i8 lmprlnted in ink.
U.S. Patent 3,616,015 i8 illustrative of the prior art. ln U.S. Patent 3,616,015 a label carrying web such as a paper sheet lncludes a heat transrerable label composed Or a wax release layer afflxed to a surface Or tlle paper sl)eet a~d an lnk deslgn layer superlmposed onto the wax release layer. In tlle heat transfer labelling process for lmprlntlng deslgtls onto artlcles, tlle label carrylng web 18 subJected to heat and the lamlrlate 19 pre~sed onto an artlcle wlth the ink deslgn layer nnaking dlrect contact with tlle article. As the web or paper ~heet 19 subJected to heat, tlle wax layer beglns to melt 80 that the paper sheet can be releaaed froln tl~e wax layer. Arter transrer Or tlle deslgn to the artlcle, tl)e paper sheet 1~ lmmedlately removed, leavlng the deslgn rirmly arrlxed to tlle surrace with the wax layer exposed to the envIronment. The wax release layer should not only permlt release Or the transferable label rrom the web upon appllcatlon Or heat to t!le web but al80 form a clear proteatlve layer over the transrerred lnk deslen.
, .
'`'~ ~ '' ' , ' .
~Z73851 This commonly assigned patent discloses a wax release coating containing a modified montan wax which has been oxidized, esterified, and partially saponified. In order to attain improved clarity of the transferred ink design the transferred wax coating over the ink design is subjected to additional heat processing after the label has been transferred onto an article. The additional processing involves postflaming, wherein the transferred wax coating is subjected to jets of high temperature gas either as direct gas flame or as hot air jets at temperatures of about 300F
to 400F for a period of time sufficient to remelt the wax coating without substantially heating the bottle. Upon cooling of the remelted wax coating through use of ambient or forced cooled air, the cooled wax layer solidifies to form a clear, smooth protective coating over the transferred ink design. Although the heat transferable label and process disclosed in U.S. Patent 3,616,015 represents an improvement over prior heat transferable labels, they are best suited to decoration of plastic articles which are not transparent.
Although the heat transferable label disclosed in this reference may be utilized for decorating a wide variety of different plastics, there can be a degree of hazing or halo noticeable over the transferred label when the transfer is made onto clear plastic materials, despite use of postflaming.
U.S. patent 2,990,311 discloses a heat transferable decal having a release transfer layer composed of a mixture of a crystalline wax and a synthetic thermoplastic film-forming resin, principally an organic linear thermoplastic film-forming resin which is substantially , , ' ' ' . ' .
385~
water insoluble. The d~gree Or compatiblllty Or the re31n and wax is controlled through selection and ratlo of the components to glve heat transfers of either the hot peel or cold peel type. In the hot peel transfer, the decal wlll adhere and release from the backlng only lmmedlately after appllcatlon whlle the decal 18 stlll hot. In the cold peel transfer the transferred decal wlll adhere to the recelvlng surface when hot but will only release and tran~fer by peellng away the backlng arter the transfer ha~ cooled. In elther type Or transrer~ thls rererence teache~ that reslns and waxes (the latter belng used for the relea~e layer) should be mutually lncompatlble or lnsoluble at temperatures below the meltlng temperature Or the wax such that the molten wax, upon coollng, wlll actually arystalllze separately and dlstlnctly rrom the re~ln. The resins are llnear thermoplastlc fllm-forming reslns deflned as essentlally solvent-soluble, sortened by heat and to lnvolve only a mlnor amount or no cross-linkage.
Sultable reslns speclrlcally dlsclosed are polyvlnyl acetate, polyethyl a¢rylate, polymethyl acrylate, polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, styrenebutadlene, acrylonltrlle-butadlene, polychloroprene rubbers, polyvlnyl butyral, ethyl cellulose, and polyvlnyl acetate vlnyl stearate copolymer (col. 5, 1. 38-44). The reference teaches that the wax ¢omponent should be a materlal whlch derlves lts crystalllnlty malnly from the presence Or lohg hydrocarbon chalns and should melt over a relatlvely narrow range between the temperatures Or about 50C to 110C. The penetrometer hardness value (ASTM D5-52) when tested wlth ; 100 grams for 5 seaonds at 28C should be below about , , ~2738Sl 15 . Specific waxes disclosed as suitable are beeswax, candelilla wax, carnauba wax, hydrogenated castor oil, montan wax, paraffin wax, low molecular weight polyethylene, oxidized microcrystalline wax, and hard wax or derivatives thereof obtained from the Fischer Tropsch synthesis.
(co.5,1.45-56). This references does not disclose applicant's formulation for the release layer nor does it contemplate the advantages which applicant has derived from such formulation.
U.S. patent 2,862,832 discloses a heat transferable decal having a release layer composed of an oxidized wax. The disclosure is directed principally to defining the type of wax found to provide suitable release of the decal from the carrier web upon application of heat. The wax disclosed in this reference is an oxidized wax obtained as the reaction product of the oxidation of hard, high melting, aliphatic, hydrocarbon waxes. The oxidized waxes are defined as the oxidation products of both natural and synthetic hydrocarbon waxes such as petroleum waxes, low molecular weight polyethylene and waxes obtained from the Fischer-Tropsch synthesis. Suitable wax may include oxidized microcrystalline wax or the esterification product of an oxidized hydrocarbon wax. The oxidized waxes are disclosed as those having melting points between about 50C and 110C, saponification values between about 25 and 100, acid values between about 5 and 40, and penetrometer hardness (ASTM D5-52) below about 51 as measured with 100 grams for 5 seconds at 25C.
Although this reference mentions that minor amounts of certain additives such as fillers and resins may be added to ~f :
~ .
.,~, .
.
~738Sl the oxidized wax, the invention is clearly concerned with the use of wax as the essential component and designation of specific wax types found to give advantageous results. This reference does not disclose applicant's principal additives or applicant's combined formulation nor does it recognize or contemplate the advantages obtained from such formulation.
U.S. Patent 3,616,176 discloses a heat transfer laminate of a type related to that disclosed in U.S. Patent 3,616,015.
In U.S. Patent 3,616,176 the laminate is composed of a base sheet, with a polyamide layer covering the base sheet and a decorative ink layer covering the polyamide layer.
Sufficient heat is applied to the laminate to heat the polyamide layer at or above a softening point, and the laminate is then pressed onto the surface of an article with the decorative ink layer coming into direct contact. Upon withdrawal of the heat source, the polyamide layer cools to a temperature below the softening point and the base sheet is removed. The decorative layer becomes fused or heat sealed to the article. The polyamide layer in the disclosure functions as a release coating which allows transfer of the decorative layer onto an article and upon cooling serves as a protective coating layer over the transferred decorative layer. The use of a polyamide release coating has the principal disadvantage in that there is a significant tendency for the polyamide to form a noticeable halo around the transferred decorative layer. Also the polyamide layer even when sub~ected to additional processing such as post-flaming does not form sufficiently clear coating that would aesthetically permit heat transfer labelling onto clear articles or bottles.
\-~
., ~, - - , ' :
-1i:'7385~
U.S. patent application Serial No. 130,303, commonly assigned with the present application, discloses a heat transfer label of the type illustrated in U.S. patent 3,616,015. In another form of heat transfer label developed by the Applicant, a carrier member (base sheet) is overcoated in designated regions with a release layer and an ink design layer. Optionally, a barrier layer is included between the release layer and the ink layer. The release layer is typically composed of a polymerization product of a diamine with the dimer of a fatty acid. In order to reduce the halo effect of the transferred release layer over the ink design layer, the release layer is contoured in a particular manner. To further reduce the halo effect, this reference teaches that the optional barrier layer included between the release layer and ink layer, be formed of an aromatic acid-based polyester covering and overlapping the release layer by a margin.
Applicant's U.S. patent No. 4,426,422 also discloses a heat transfer label of the type illustrated in U.S. Patent
3,616,015. The heat transfer label disclosed in U.S. Patent No.
4,426,822 is composed of a carrier member (base sheet) overcoated in designated regions with a release wax layer, a protective barrier layer, an ink design layer, and an adhesive layer. The protective (barrier) layer is placed preferably between the release wax layer and the ink design layer. The protective layer provides enhanced chemical resistance for the heat transfer label , .p ', ~
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-7a-and permits the heat transfer label to resist distortion during the heat transfer process without sacriEice in label clarity.
Accordingly, it is an object of the present invention to provide an improved release for heat transferable substrates which permits transfer of an ink design image from a support member to a pla~tic or glass container.
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127385~
It 18 an important obJect to provide a relea3e whlch has improved optical clarity and required relea3e and adhesive properties.
It is a further ob~ect to provide an improved release and heat transferable substrate rOr use ln transfer Or optl¢ally clear design image from a support to a clear plastl¢ or glass contalner. A related obJect is to provide an improved optlcally clear release whlch also functlorls as a prote¢tive ¢oatlng for the transrerred image.
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~273851 SUMMERY OF THE INVENTION
In accomplishing the foregoing and related objects, the invention provides a heat transferable laminate of the type comprising a substrate affixed to a support member for transfer from said support member to an article upon application of heat to said support member while said article is in contact with said substrate, said substrate comprising in sequence a release layer in contact with the support member and an ink design layer over the release layer, said release layer comprising in combination:
a paraffin wax composed of linear saturated Cl~ to C32 hydrocarbons having a melting point between about 110F and 150F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60C and 135C, oxidation resistance under ambient conditions, and has Color Gardner Nos.
of between about 1 and 4.
The invention also provides a heat transferable laminate of the type comprising a substrate affixed to a support member for transfer from said support member to an article upon application of heat to said support member while said article is in contact with said substrate, said substrate comprising in sequence a release layer in contact with the support member and an ink design layer over the release layer, said release layer comprising in combination: a paraffin wax composed of linear saturated C" to C32 hydrocarbons having a melting point between about ~10F and 150F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60C
and 135C, oxidation resistance under ambient conditions, and has Color Gardner Nos. of between about 1 and 4, and wherein said paraffin wax comprises between about 15 to 30 percent by weight of said v~
, . ~.
12'73851 -sa-release layer, the montan wax comprises between about 15 to 35 percent by weight of said release layer, and the tackifying polymer comprises between about 15 to 50 percent by weight of said release layer.
An important aspect of the invention is an improved formulation for the release layer. The improved release formulation has the advantage that it produces an optically clear, transparent, protective layer over the transferred ink design layer. Consequently, the improved release coating has distinct advantage in the application of heat transferable laminates to plastic or glass containers, and in particular to clear plastic or glass containers.
The clarity of the transferred release coating forming a protective coating over the transferred ink design layer is of a degree heretofore unachievable. The transferred release layer is optically clear to the unaided eye when viewed against a clear plastic or glass B
.
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container. There 18 n~ hazlng, spotting, or halo efrect discernlble over the tran~rerred ink design layer regardless Or whether the heat transrerable laminate i~
applied to opaque or clear artlcles.
The improved release layer of the lnvention contalns a crystalline wa~c such as pararrln wax or microcrystalllne wax, and a taoklrylng agent. Preferably the lmproved release contalns a crystalllne wax, such as parafrln wa~, a montan wax, and tacklrylng re~ln. It has been de'cermlned to be hlghly deslrable to sele¢t a ta¢klrylng resln whlch 1B composed Or an optl¢ally ¢lear, nonwax hydrocarbon polymer havlng a sortenlng polnt (Ball and ~lng method) between about 60C and 135C, preferably between about 85C and 125C, and a ¢olor Gardner number Or about 4 or less, more preferably between about 1 and 3. The prererred ta¢klrylng resln lmproves the adhesiveness Or the release layer without destroylng the release propertles Or the wa~. The ta¢klrylng resln also enhan¢es the optl¢al clarlty Or the release layer. A
tacklrylng resln determlned to have these advantageous propertles 18 a hydrogenated hydrooarbon resln. More speairlcally, the hydrogenated hydrocarbon resln determlned to have the arorementioned advantageous ;~ ~ propertles 18 the produ¢t Or a ayallc monomer whl¢h 18 25 polymerized and subsequently rully hydrogenated. The ayclia mo~nomer 18 prererably a C4 to C8 hydroaarbon monome~r. A prererred taaklrylng resln is the produ¢t Or ay¢lopentadlene monomer whl¢h 18 polymerlzed and subsequently rully hydrogenated. Another prererred ta¢kirylng resln 18 rormed rrom the product Or styrene monomer whl¢h 18 polymerlzed and subsequently rully hydrogenated.
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'' ' .' " , ' ' ' ' : , ,, , ~ , ~2738~;1 Appllcant has determined that lncluslon Or a tacklrying re~in from the above ola~ses Or hydrogenated hydrocarbon resin increases the adheslveness Or the release layer wlthout destroying the release propertles of the wax and simultaneously, qulte unexpectedly, reduces the amount Or crystalllne structure Or the solldiried wax to a greater degree than mlght be expected from dilutlon Or the wax wlth other reslns or dlluents in the same proyortlon. 1'he slgnlrl¢ant reductlon in total crystalllnity Or the wax 18 belleved to markedly enhance the optlcal clarlty Or the wax upon resolldirication.
A prererred rormulatlon rOr the lmproved release coating may also include microcrystalline wax. l'he miaro¢rystalllne wax 18 typlcally compo~ed Or saturated hydrocarbons Or hlgher meltlng polnt than that Or pararfln wax. The mlcrocrystalline wax is characteristlcally composed Or about C34~l70 to C60H120 ~ydrocarb In addition to the microcrystalline wax, the preferred rormulation for the improved release coating may advantageously contaln a resln blnder, whlch blnds the components Or the relea~e ln a homogeneous mlxture which orms a hot melt and thus obviates the need ror a solvent.
A prererred binder is a copolymer Or ethylene and vinylacetate or a terpolymer Or ethylene, vinyl acetate and acryllc acid.
In the preferred release rormulation, the para~rrln wax may be present in an amount between about 15 to 30 weight percent; the montan wax between abcut 15 to 35 weight percent; and the tackirylng resin in an amount between about 15 to 50 weight percent. The weight ratlo Or montan wax to tackifylng resln advantageously ralls in ; the range rrom ~bout 0.3/1 to 2.3/1. The lmproved release rormulatlon Or the lnventlon ln appllcable to any heat , - . : .
: . :
lZ738S:l transferable lamlnateror the type whereln the ob~ective i8 to transfer an lnk deslgn lmage from a carrier web to an artlcle upon the appllcatlon Or heat and pressure to the lamlnate.
~i , '' '"' , ' " ' ,' ' lZ738S~
-7a-and permits the heat transfer label to resist distortion during the heat transfer process without sacriEice in label clarity.
Accordingly, it is an object of the present invention to provide an improved release for heat transferable substrates which permits transfer of an ink design image from a support member to a pla~tic or glass container.
_ A '.,, ' ' , ''' '' ~ ' `
127385~
It 18 an important obJect to provide a relea3e whlch has improved optical clarity and required relea3e and adhesive properties.
It is a further ob~ect to provide an improved release and heat transferable substrate rOr use ln transfer Or optl¢ally clear design image from a support to a clear plastl¢ or glass contalner. A related obJect is to provide an improved optlcally clear release whlch also functlorls as a prote¢tive ¢oatlng for the transrerred image.
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.
.: , . - , .
~273851 SUMMERY OF THE INVENTION
In accomplishing the foregoing and related objects, the invention provides a heat transferable laminate of the type comprising a substrate affixed to a support member for transfer from said support member to an article upon application of heat to said support member while said article is in contact with said substrate, said substrate comprising in sequence a release layer in contact with the support member and an ink design layer over the release layer, said release layer comprising in combination:
a paraffin wax composed of linear saturated Cl~ to C32 hydrocarbons having a melting point between about 110F and 150F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60C and 135C, oxidation resistance under ambient conditions, and has Color Gardner Nos.
of between about 1 and 4.
The invention also provides a heat transferable laminate of the type comprising a substrate affixed to a support member for transfer from said support member to an article upon application of heat to said support member while said article is in contact with said substrate, said substrate comprising in sequence a release layer in contact with the support member and an ink design layer over the release layer, said release layer comprising in combination: a paraffin wax composed of linear saturated C" to C32 hydrocarbons having a melting point between about ~10F and 150F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60C
and 135C, oxidation resistance under ambient conditions, and has Color Gardner Nos. of between about 1 and 4, and wherein said paraffin wax comprises between about 15 to 30 percent by weight of said v~
, . ~.
12'73851 -sa-release layer, the montan wax comprises between about 15 to 35 percent by weight of said release layer, and the tackifying polymer comprises between about 15 to 50 percent by weight of said release layer.
An important aspect of the invention is an improved formulation for the release layer. The improved release formulation has the advantage that it produces an optically clear, transparent, protective layer over the transferred ink design layer. Consequently, the improved release coating has distinct advantage in the application of heat transferable laminates to plastic or glass containers, and in particular to clear plastic or glass containers.
The clarity of the transferred release coating forming a protective coating over the transferred ink design layer is of a degree heretofore unachievable. The transferred release layer is optically clear to the unaided eye when viewed against a clear plastic or glass B
.
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container. There 18 n~ hazlng, spotting, or halo efrect discernlble over the tran~rerred ink design layer regardless Or whether the heat transrerable laminate i~
applied to opaque or clear artlcles.
The improved release layer of the lnvention contalns a crystalline wa~c such as pararrln wax or microcrystalllne wax, and a taoklrylng agent. Preferably the lmproved release contalns a crystalllne wax, such as parafrln wa~, a montan wax, and tacklrylng re~ln. It has been de'cermlned to be hlghly deslrable to sele¢t a ta¢klrylng resln whlch 1B composed Or an optl¢ally ¢lear, nonwax hydrocarbon polymer havlng a sortenlng polnt (Ball and ~lng method) between about 60C and 135C, preferably between about 85C and 125C, and a ¢olor Gardner number Or about 4 or less, more preferably between about 1 and 3. The prererred ta¢klrylng resln lmproves the adhesiveness Or the release layer without destroylng the release propertles Or the wa~. The ta¢klrylng resln also enhan¢es the optl¢al clarlty Or the release layer. A
tacklrylng resln determlned to have these advantageous propertles 18 a hydrogenated hydrooarbon resln. More speairlcally, the hydrogenated hydrocarbon resln determlned to have the arorementioned advantageous ;~ ~ propertles 18 the produ¢t Or a ayallc monomer whl¢h 18 25 polymerized and subsequently rully hydrogenated. The ayclia mo~nomer 18 prererably a C4 to C8 hydroaarbon monome~r. A prererred taaklrylng resln is the produ¢t Or ay¢lopentadlene monomer whl¢h 18 polymerlzed and subsequently rully hydrogenated. Another prererred ta¢kirylng resln 18 rormed rrom the product Or styrene monomer whl¢h 18 polymerlzed and subsequently rully hydrogenated.
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'' ' .' " , ' ' ' ' : , ,, , ~ , ~2738~;1 Appllcant has determined that lncluslon Or a tacklrying re~in from the above ola~ses Or hydrogenated hydrocarbon resin increases the adheslveness Or the release layer wlthout destroying the release propertles of the wax and simultaneously, qulte unexpectedly, reduces the amount Or crystalllne structure Or the solldiried wax to a greater degree than mlght be expected from dilutlon Or the wax wlth other reslns or dlluents in the same proyortlon. 1'he slgnlrl¢ant reductlon in total crystalllnity Or the wax 18 belleved to markedly enhance the optlcal clarlty Or the wax upon resolldirication.
A prererred rormulatlon rOr the lmproved release coating may also include microcrystalline wax. l'he miaro¢rystalllne wax 18 typlcally compo~ed Or saturated hydrocarbons Or hlgher meltlng polnt than that Or pararfln wax. The mlcrocrystalline wax is characteristlcally composed Or about C34~l70 to C60H120 ~ydrocarb In addition to the microcrystalline wax, the preferred rormulation for the improved release coating may advantageously contaln a resln blnder, whlch blnds the components Or the relea~e ln a homogeneous mlxture which orms a hot melt and thus obviates the need ror a solvent.
A prererred binder is a copolymer Or ethylene and vinylacetate or a terpolymer Or ethylene, vinyl acetate and acryllc acid.
In the preferred release rormulation, the para~rrln wax may be present in an amount between about 15 to 30 weight percent; the montan wax between abcut 15 to 35 weight percent; and the tackirylng resin in an amount between about 15 to 50 weight percent. The weight ratlo Or montan wax to tackifylng resln advantageously ralls in ; the range rrom ~bout 0.3/1 to 2.3/1. The lmproved release rormulatlon Or the lnventlon ln appllcable to any heat , - . : .
: . :
lZ738S:l transferable lamlnateror the type whereln the ob~ective i8 to transfer an lnk deslgn lmage from a carrier web to an artlcle upon the appllcatlon Or heat and pressure to the lamlnate.
5 BRI~F D~SC~IPTION OF TIIE DRAWINGS
~lgure l 18 an lllu~tration Or a preferred embodlment o~ the composlte heat transferable lamlnate; and Figure 2 18 an lllustratlon of another preferred embodlment of the composlte heat transferable lamlnate.
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12738~ii D~TAIL~D DESCRIPTION
The prererred embodlment of the heat transferable lamlnate 5 Or the invention as illustrated in Figure l 18 compo~ed of a carrier web 10, typically paper, overcoated with a release layer 20 and ink design layer 30.
Optionally an adheslve layer 4O may be included over design layer 30 as lllustrated in~igure 2. Release layer 20, design layer 30 and optional adhesive layer 40 rorm a transferable substrate 15, which relea~es from carrier web 10 upon application of heat to web 10 sufficient to melt relea~e layer 20. As an artl¢le or surrace 18 pressed onto the exposed surface Or substrate 15, it ~plits rrom ¢arrier web 10 and transrers onto the surrace Or the article wlth ink design layer 30 clearly imprlnted on the article.
The heat transrerable laminate Or the inventlon satisries a number Or requirements slmultaneously.
Release layer 20 and lnk de~lgn layer 30 are first Or all easily coated onto carrler web 10 when the release layer 20 18 in a molten state. Coatlng Or carrler 10 18 readlly efrected preferably by gravure methods but other printing methods such as letterpress, rlexographlc, or screen printing as well a~ cast coating methods such as reverse roller coatlng may be employed ln coatlng release layer 20 onto carrler web 10. Ink deslgn layer 30 is readlly coatable on release layer 20 by use prererably Or gravure , technique, although other cast coatlng methods and screen printlng methods may also be used. Release layer 20 and ink design layer 30 Or the inventlon have the required physical properties that permit coatlng by the prererred gravure technlque without "plck orr" problems occurrlng;
that 18, wlthout causlng removal Or a portlon Or release - - , . , - ~ '-. ' lZ73~5~
layer 20 as the ink design layer 30 is coated thereon.
Release layer 20 also has the required properties that prevent embossing of the wax during printing of design layer 30 and also prevents ink striking into the wax during printing and ink migration into the wax after printing.
Release layer 20 is of a formulation which also prevents nonuniform splitting of the release layer during the heat transfer process and thereby prevents insufficient or uneven transfer of the release layer from the carrier web during the transfer process. In addition to having the requisite release property upon heating, release layer 20 also has sufficient adhesive properties upon cooling which keeps design layer 30 adhesively bonded to the article being imprinted and also forms a clear glossy protective coating layer over the transferred design layer 30. The clarity, smoothness, and glossiness of release layer 20 is improved by subjecting transfer substrate 15 to postflaming after substrate 15 has been transferred to an article. The postflaming may be accomplished by exposing the transferred substrate to jets of hot gas either as direct gas flame or as hot air jets for a period of time sufficient to remelt the wax, as for example by the methods described in U.S. patent 3,616,015. After postflaming layer 20 resolidifies quickly upon exposure to ambient conditions to form a smooth, glossy film of improved clarity. The resolidified layer exhibits so high a degree of clarity and translucency that there is virtually no visible halo or hazing either around or over the surface of the transferred design image 30. This results in remarkable clarity in the transferred design image. Thus, the laminate 5 is suitably applied to plastic and glass articles of a variety of shades, as well as to .....
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~2738Sl artlcles and contalne~rs composed Or optlcally clear plastlc materlals such as polyvlnylchlorlde and polyethylene terepthal&te or clear polyethylene or polypropylene. Prior art heat transrerable laminates, 5 although exhibitlng hlgh degree Or optlcal clarlty upon postrlaming, have some llmitation in application to optically clear plastics since there can be ~ome hazlng or halo discernible upon transrer onto optlcally clear materlals.
The virtual eliminatlon Or hazing or halo has been accompllshed while slmultaneously satisrying all other physlcal property requlrements rOr an errectlve release coatlng rOr a heat transrerable substrate as has been discussed ln the roregoing. Addltlonally thls lmprovement 1,5 has been made wlllle redu~lng the amount Or montan wax ln the preferred formulatlon. Slnce montan wax 1B a costly constltuent, appllcant has reallzed slgnlrlcant cost savlngs ln the preferred formulatlon ror release coatlng 20.
The preferred rormulatlon rOr relea~e layer 20 is a hot melt contalning pararfin and a montan wax which may also lnclude a minor amount Or mlcrocrystalline wax. In additldn to these waxes, the formulation includes a ta¢klrylng resln and sultable blnder. Appllcant has dlscovered ~ulte unexpectedly that, wlth proper selectlon Or tacklfler resln, the total amount Or crystalllnlty Or the parafrln wa% can be reduced slgnlrlcantly, more than would occur by addltlon Or other reslns or dlluents Or equal amount. It 18 not known wlth certalnty all of the ractors responslble for the hlgh degree Or clarlty and translucency Or the transrerred layer 20, but the reductlon ln lnherent crystalllne structure Or the pararrln wax aod to an extent the mlcrocrystalllne wax, as .
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lZ'73~3S
well, 18 believed to be the principal factor. Although it 18 known that the lnherent crystallinity of certain waxes, partlcularly pararfln wax, used in release coating ror heat transrerable laminates is a princlpal cau~e of the hazing erfect~ it has been heretorore not been posslble to reduce the crystalllnlty Or the solidiried wax without disrupting other lmportant physlcal propertles Or the release lager. Although postrlaming serves to reduce some Or the hazlng whi¢h appears over the transrerred lmage it erreats only a partial reductlon and does not decrease the crystallinlty o~ the wax components. Postflaming has been determined to lncrease clarlty prlnclpally because lt has the erfect Or smoothing mlcroscoplc hills and valleys on the surrace Or the transrerred release layer. Post~lamlng thus crea~es a smoother, more unirorm surrace Or glossy character, lncreases the overal~ clarity Or the transrerred release layer, and consequently the clarity of the transrerred deslgn image. Resldual amount Or opacity or ha~lng is believed to be caused bg the crystalllne structure Or the solidlried pararrin wa~ and to a lesser degree Or the ~olidlfled microcrystalline wax which contalns crystals Or much smaller size.
It i~ deslrable to select a thermoplastlc tacklrylng resln whlch is composed Or an optically clear, nonwax hydrocarbon polymer havlng a sortenlng polnt (Ball h ~ing Metkod ASTM E-28) between about 60C and 135C, more prererably between about 85C and 125C, and most prererably between about 100C and 125C. Appllcant has ~ound a partlcular polymer class Or thermopl~stlc reslns whlch when added to the release rormulatlon, lncrease the adhesiveness Or the release layer and qulte unexpectedly reduces the amount Or crystalllne structure ln the solldlrled wax. Thls reduction 18 greater than , , . -, : ' ' 12738Si mlght be expected from dilution Or the wax wlth otherresln~ or dlluents added in the same proportlon. The marked reduct~on in total crystalllnlty Or the wax, it ls theorlzed, enhances the optical clarity Or the wax upon resolldlricatlon. The solldlried release layer has a color ~ardner No. between about 1 and 4. The tackirying resln also prererably has a color Cardner number between about 1 and 4, typlcally between about 1 and 3.
The polymer class ror the tackifylng resln having the above-descrlbed properttes and determined to unexpectedly reduce the amount Or crystalllne ~tructure ln the solldiried wax 18 a transparent nonwa~ hydrogenated hydrocarbon resin. More specirioally, lt is the product Or a cycllo hydrocar~on monomer which has been polymerlzed and subsequently rully hydrogenated to completely saturate the polymer. Suitable cycllc hydrocarbon monomers which are polymerized and subsequently rully hydrogenated to rorm the tacklfylng resln component are prererably selected from C4 to C8 cycll¢ hydrocarbon monomers.
A prererred tacklfylng resln is rormed Or cyclopentadlene monomer whlch 18 polymerlzed and 8ubsequently rully hydrogenated. A tacklrylng resln Or thls latter type employlng cyclopentadlene monomer whlch 18 polymerl~ed and subseque~tly fully hydrogenated 18 avallable under the ESCOREZ serles reslhs rrom Ex~on Chemlcal Company. ~ preferred tacklrylng resin Or the ESCOREZ serles ls ESCOREZ 5300 resin. Thls resln has a water whlte color (Color aardner No. Or 3 or less); a Ball and Rlng sortenlng polnt Or about 105C; a speclrlc gravity (60/60F) Or 1.10; a Brookrleld vlscoslty (70 percent ln toluene at 60F) Or about 130 centlpol~e; and a fla~h polnt (COC) Or about 210C.
~ c~é,ro~
12738Sl An alternative pr~ferred ESCOREZ re~in having a somewhat higher ~ortenlng point is ESCOREZ'5320 resln.
The latter resin has a water white color (Color aardner No. of 3 or less); a Ball and Ring sortening point Or about 125C; a speairlc gravlty (60/60~) Or 1 10; a Brookrield viscoslty (70 percent ln toluene at 60F) Or about 350 centipoise; and a rlash point (COC) ~r about 243C. ~n alternatlve p~eferred tackirying resin is a transparent nonwax hydrogenated hydrocarbon resin rormed Or styrene monomer which is polymerlzed and subsequently rully hydrogenated. A re~ln ~r thls latter type 18 avallable under the nEaAL~EZ tradename from llercules ,, Chemlcal Company. A speciflc REaAL~EZ resln round to be partlcularly suitable ror use as the tacklrylng re~ln ln the present lnvention 18 REa~LREZ 1126, whlch has a crystal clear color; a Ball and ~lng sortening point Or between about 122C to 130C; a speciric gravit,y at 21C Or o 97; an acld number Or less than 1-0; and a melt vlscosity Or 1 poise at 209C and 10 polse at 182C; and a rlashpolnt (COC) Or 243C.
The use Or a tacklrylng resin from the above-descrlbed classes ln appll¢ant's hot melt rormulation rOr wax release layer 20 has an addltlonal advantage over aonventlonal resins such as pentarerythrltol ester Or hydrogenated rosln used in prior art wax release formulatlorls. Such reslns may oxidlze over a period Or tlme causing a dulllng erfect ln the appearance Or the transrerred deslgn lmage. In contrast, the tacklrylng reslns employed ln the present rormulatlons for release 3~ layer 20 do not o~ldlze wlth tlme after the substrate 15 has been transrerred onto an artlcle.
The parafrin wax aomponent Or the formulation ror release layer 20 18 used to glve layer 20 lts pr,inclpal ..... . .
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lZ738~1 release characteristic upon meltlng. Pararrin wax, a petroleum derived product, typlcally ha~ a molecular welght between about 25l1 to 450 and i8 composed essentially Or linear saturated hydrocarbons ranging from C181~38 to C32ll66 Pararflns typlcally have a meltlng polnt from about 110 to 150F. ("Meltlng polnt"
as uced herein refer~ to drop melting point). A Preferred parafrin wax ror use in the rormulation Or the present lnvention is composed Or llnear saturated hydrocarbons ranglng from C26ll51l to C32~i66 havlng a meltlng polnt between about 145F to about 155F.
The pararrin wax, a llnear saturated hydrocarbon, ls characterlzed ln that lt crystalllzes in both plate and needle-type crystals, partlcularly the rormer. ~nother type Or crystalllne structure, termed malcrystalllne, 18 nelther plate nor needle-like and 18 observable ln the parafrln crystal structure ln amount dependlng on the bolllng polnt Or the pararfln rractlon belng lnvestlgated.
In parafrln wax rractlons Or lower bolllng point, for example about 1~0~ at 10 mm pressure, the entlre ¢rystalline structure is composed Or plates. ~n pararrln wax rractions having somewhat higher boillng points, a mlnor amount Or malcrystalllne and needle-llke structures mag be observable interspersed among the plate-llke structures. In general, the plate crystals predominate in pararrin waxes Or any bolllng range. Ilowever, ln the hlgher meltlng pararrln waxes where there is likely to be some increased amount of branchlng associated with their structure, there 18 llkelg to be a greater portlon Or malcrystalline and needle-like crystals lnterspersed among the plates. m e tgpe and amount Or crystals round ln parafrln wax is principally an inherent runction Or the boillng polnt range Or pararrlns being investigated lrrespective Or the solvent or medlum used from which the crystalllne solld 18 preclpltated.
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1~73851 Parar~in wax suitable for use ln release layer 20 18 sold in varlous grades which dlrfer chierIy in melting point. Commerclal grades Or parafrin wax whlch may be used in release layer 20 are commonly designated a~
rerlned~ semire~ined, and crude grade waxes. or these the rerlned grade i~ prererred for use in the present formulation rOr release layer 20. Parafrin wax Or rerlned grade is obtainable from a number Or source~, one Or which is the Petrolite Corp., Bareco DiYisionJ Or Tulsa, Oklahoma.
The miGrocrystalline component Or rormulatlon 20 is composed Or saturated hydro¢arbons Or higher melting point than those Or pararfln wax. Micro¢rystalline waxes chara¢teristlcally contain between about C341170 to C60~1120 hydro¢arbons having molecular weight between about 478 and 840. Microcrystalline waxes (mlcro-waxes) are characterized by an lncreased amount Or branchlng;
although they contain straight ohain molecules, they are - not as linear a saturated ~ydro¢arbon as pararrin wax.
Also compared to pararrin wax, they contain a greater portlon Or cyclic ring molecules. The crystalline structure Or the microcrystalllne wax contains predomlnantly malcrystalllne and needle-like crystals havlng very small underlned form when compared wlth the plate-llke crystalllne structure Or pararrin wax under the same magnificatlon. Thus the crystalllne structure Or mlcrocrystalline wax 18 small and irregular when ; solldlrled rrom the melted wax. In solvents mlcrocrystalllne wax dlscloses no well-rormed crystals Or any size. Small amounts Or mlcrowax are advantageously added to the formulatlon ror release layer 20, slnce mlcrQwax lmparts a measure Or plasticity to the pararrin wax componente, clnco tho pararrln wqx 1~ rather brlttle .
' and would by itself tend to cause cracks or fissures in a wax release layer. Because of its diminished crystalline structure, microwax contributes little potential hazing or halo effect.
The classes of microwaxes vary principally in their melting point range. For example, the so-called hard microwaxes have a melting point between about l9o to 210F; the plastic mircowaxes a melting point between about 145 to 175F; the emulsifiable crystalline waxes between about lso to 225F; and modified microwaxes between about 165 to 220F. All of these various types of microwaxes may be employed in the present formulation; however, the plastic type (BAREC0 designation) is most preferred. An illustrative, commercially available microcrystalline wax which is particularly suitable in the present formulation is available under the Victory White tradename from the Petrolite Corp.
The montan wax component for release layer 20 iS a coal (lignite) derived wax characterized by high concentration of montanic acid (C"H~60~). Montan wax has been determined to be a very suitable additive to increase the hardness of release coating 20, as well as its lubricity. Additionally, montan wax promotes a smooth glossy texture of the release coating after transfer. Montan wax also prevents penetration of the release coating into the paper carrier 10, as it forms a formation of a hard protective barrier coating over the transferred design layer.
A particularly suitable type of montan wax is an oxidized, esterified, partially saponified montan wax as disclosed in U.S. Patent 3,616,015. Montan waxes of this type have melting points (drop points) typically between about 50 and 110C, .
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saponiflcation value~ ~etween about 25 ~nd 150, acid values between about 5~ and 40, and penetrometer hardnes~
(ASTM-D5-52) below about 15 as measured with 100 grams for 5 second~ at 25C. The~e montan waxes also have 5 relatively hlgh melt vlscoslty. An lllustratlve oxldlzed, esteriried~ partlally saponlrled montan wax is avallable under the tradename ~loech~t OP or Hoech~t X55 modlried montan wax from the Hoechst Chemical Company, (location).
I50ech~t OP modlried montan wax has a drop polnt 10 (ASTM D12l) Or 212 to 221~, a congealing point (ASTM D938-49) between 165 and 175F, an acld number Or 1~ to 15, and a ~aponirication number Or 100 to 115.
Iloe¢hst X55 has a drop polnt of 20~ to 218F, a congealing polnt Or 167 to 176~, an acid number Or 10 15 to 15, and a saponlrlcation number Or 90 to 110. The~e waxes have melt viscoslties Or at least about 150 centlpolse at a temperature Or about 25F above thelr solldlricatlon point.
A partlcularly suitable blnder ln the preferred 20 release formulation i8 a copolymer Or ethylene and vlnyl~¢etate, such as that avallable under the tradename Elvax 410 ~rom E.I. duPont Company, Wllmlngton, DE. The blnder 18 used prlncipally to blnd the components Or the release rormulation trelease layer 20) ln a homogeneous 25 mlxture, whlch rorms a hot melt and does not require a solvent. The varlous components Or the release formulation do not copolymerl~e ln any measure durlng the coatlng stage or durlng meltlng and subsequent resolldlrlcatlon Or release layer 20. A blnder Or 30 copolymer Or ethylene and vinylacetate such as Elvax 410 18 most preferred because lt provldes hlgh optlmum gloss ln blends with wax. However, other blnders Or ethylene and vlnylacetate copolymer, as ror example, ~lvax 210, . . .
~Z73851 310, may be used. An alternative blnder in the ~LVAX
serles such as Elvax~4310 which 18 ethylene vlnylacetate acryllc acld terpolymer has also been determined to be sultable. Also ln place Or the above-referenced blnders acryllc acid terpolymer has also been determined to be an ethylene acryllc acld copolymer blnder may be employed.
A sultable blnder Or thls latter type 18 available under the tradename ~C-540 rrom Allled Chemical Company.
Prererred ¢omposltlons ror release layer 20 are shown ln Table I. Although spe¢lrl¢ rormulatlons rOr the release layer 20 are glven ln Table I, lt has been determlned that the pararrln wax may be present ln release layer 20 ln an amount between about 15 to 30 weight percent, prererably between about 20 to 25 welght percent.
me montan wax may be present ln release layer 20 ln an amount between about 15 to 35 welght percent, and the tacklrylng resln ln an amount between about 15 to 50 welght percent, prererably about 35 to 45 welght percent.
ffl e weight ratlo Or montan wax to tacklrylng resln may be ln a range between about 0.3/1 to 2.3/1.
:
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~'.' ~ ' ' '. ', , ~Z7~851 T A B L E
F~n~UL~ A B ~ ~
Wt. Wt. Wt. Wt.
Z % %
Pararrin Wax 22 22 22 22 Mlcrocrystalline Wax: (eg. BARECO
Vlctory White) 4 4 4 4 Montan Wax:
(eg. IJoe¢hst OP
or X-55) 27 27 27 27 Taaklrier Resln:
(~Iydrogena ted IJydroaarbon Polymer 15 --e.g. ESCOREZ 5300) 41 41 e.g. ESCOREZ 5320 41 e.g. REaALREZ 1126 41 Blnder:
(Ethyleile and Vlnyl-acetate aopolymer) ELV~X - 410 6 6 6 _ TOTAL 100 100 lOO lOO
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, ~ ny of the formulations of Table I can be prepared by addlng the llsted c~mponents in the proportlons shown to a sultable heatlng vessel and stirred thereln at a temperature of about 250 to 280F until a homogeneous hot melt mixture 18 obtained.
The hot melt is coated preferably by roller or gravure onto carrler 10 ln any desired slze and pattern, thus rormlng relea~e layer 20. When aoating wlth the prererred gravure technique, the thickness is convenlently adJusted by use Or proper gravure cyllnders. The thlckness Or coated release layer 20 is preferably less than about 0.001 lnch. Other coatlng technlque~ such as cast ¢oatlng, particularly reverse roller coatlng, letterpres3, and flexographlc techniques, mag be employed.
Arter coatlng release layer 20 onto carrier 10, the coating quickly becomes solidifled upon exposure to a water cooled roller. Upon solidlflcatlon Or release layer 20, an lnk deslgn layer 30 may be applied over thls layer typically using the same coating technique previously employed.
The lnk deslgn layer 30 18 preferably applled 80 that release layer 20 e~tends beyond the deslgn layer. The lnk deslgn layer 30 may be composed Or any conventlonal lnk Or any color. The ink may typically include reslnous blnder bases compatlble with the lnk plgment employed. The lnk blnder may be selected rrom a wlde varlety Or conventional reslnous bases such as polyamlde, polyvlnyl chloride, acryllcs, and polyamlde nltrocellulose.
It 18 advantageous to overlay lnk layer 30 wlth an adheslve coatlng 40 whlch racllitates transfer Or substrate 15 to the article to be de¢orated. In this case 1273~51 substrate 15 may there~ore typlcally be composed Or release layer 20, ink~design layer 30 and adhesive layer 40 as illustrated in Figure 2. Adheslve layer 40 may suitably be composed of a thermoplastlc polyaloide adhesive. A preferred thermoplastic polyamlde adheslve ls the reaction product Or a diamine wlth a dimerlzed ratty acid such as that available under the tradename VERSAMID
900 serles from Henkel Corp. Or Mlnneapolis, Minn. It has been found advantageous to combine thls polyamlde constltuent wlth a nltrocellulose base ln adheslve layer 10.
In use, carrler web 10 18 heated to a temperature typlcally rrom about 375 to 400P, i.e. surflcient to melt the release coatlng 20. Thls may be convenlently accomplished by conveylng lamlnate 5 over a hot platen ror a perlod surrlclent to melt release coatlng 20.
Alternatively the article to whlch lamlnate 5 is to be applled may be preheated to a temperature surriciently high to melt release layer 2n as laminate 5 is pressed agalnst the artlcle.
Lamlnate 5 is applled to the article to be decorated by presslng the heated lamlnate onto the article 80 that the topmost lager Or trRnsrer substrate 15, ror example lnk deslgn layer 30 or optional lager 40 contacts the artlcle. ~olllng pressure 18 applled over the exposed surrace Or carrler 10 to erfect transrer Or substrate 15 onto the article. m ereupon carrier 10 18 peeled from substrate 15 while release layer 20 is in molten state, leaving substrate 15 permanently arrlxed to the artlcle with design image clearly vlsible through transrerred release layer 20. Upon exposure to ambient conditlons for a short perlod, release coatlng 20 solidiries to a clear, :
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1~7~8Sl ~mooth glos~y protective layer over transrerred ink deslgn lmage 30.
The clarity Or the coatlng 20 over deslgn lmage 30 at thls polnt in the proceBB 18 dlstlnctly greater than the clarlty of the transferred release layer at the same polnt in the process as descrlbed ln U.S. Patent 3,616,015.
Transrerred substrate 15 may optionally be exposed to postrlamlng to remelt transrerred coating 20 and thus further improve the clarity and gloss of transrerred coating 20 and consequently clarlty Or transferred design image 30. Postrlaming may be accomplished, rOr example, by exposing the transrerred substrte 15 includlng transrerred coating 20 to Jets Or hot gas elther as dlrect ga~ rlame or as hot alr ~ets typlcally at about 300F to 400~ or hlgher ror a perlod surrl¢ient to melt the wax ln the manner deecribed in U.S. Patent 3,616,015. Upon exposure to amblent atmosphere, coatlng 20 resolidlrles to a rllm Or such high degree Or clarltg and transparency that hazing or halo errects are virtually undetectable by the unalded eye. The clarlty Or transrerred coating 20 and design image 30 is such that the heat transrerable substrate herein described may be used to decorate virtually any plastic or glass article. For example, the substrate 15 18 well suited to the decoration Or such materials as polyvinylchloride, polyethylene terephthalate, polyethylene, and polypropylene.
Although the lnvention has been described within the context Or particular embodiments for the transrerable substrate, the invention 18 not lntended to be limlted to any partlcular composltion or layer structure for the transrerable substrate. It 18 known that the transrerable subetrato may contaln other co~tlng lnyer~, for e~mple, - ' ' , - -, -, 1;~73~Sl a plurallty Or lnk deslgn layers or separate adhesive layer over the ink design layer as well as barrier type layers between the ink deslgn layer and release layer.
The inventlon is equally applicable to such varying heat transrerable ~tructures. It should be appreciated that the release rormulation Or the inventlon has wide appll¢ation as a release coating for any heat transrerable subetrate ln aontact with a support member such as a carrier web. The lnventlon, thererore, 18 not lntended to be limlted to the de~cription in the ~pecification but rather is derined by the claims and equivalent~ thereof.
~lgure l 18 an lllu~tration Or a preferred embodlment o~ the composlte heat transferable lamlnate; and Figure 2 18 an lllustratlon of another preferred embodlment of the composlte heat transferable lamlnate.
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12738~ii D~TAIL~D DESCRIPTION
The prererred embodlment of the heat transferable lamlnate 5 Or the invention as illustrated in Figure l 18 compo~ed of a carrier web 10, typically paper, overcoated with a release layer 20 and ink design layer 30.
Optionally an adheslve layer 4O may be included over design layer 30 as lllustrated in~igure 2. Release layer 20, design layer 30 and optional adhesive layer 40 rorm a transferable substrate 15, which relea~es from carrier web 10 upon application of heat to web 10 sufficient to melt relea~e layer 20. As an artl¢le or surrace 18 pressed onto the exposed surface Or substrate 15, it ~plits rrom ¢arrier web 10 and transrers onto the surrace Or the article wlth ink design layer 30 clearly imprlnted on the article.
The heat transrerable laminate Or the inventlon satisries a number Or requirements slmultaneously.
Release layer 20 and lnk de~lgn layer 30 are first Or all easily coated onto carrler web 10 when the release layer 20 18 in a molten state. Coatlng Or carrler 10 18 readlly efrected preferably by gravure methods but other printing methods such as letterpress, rlexographlc, or screen printing as well a~ cast coating methods such as reverse roller coatlng may be employed ln coatlng release layer 20 onto carrler web 10. Ink deslgn layer 30 is readlly coatable on release layer 20 by use prererably Or gravure , technique, although other cast coatlng methods and screen printlng methods may also be used. Release layer 20 and ink design layer 30 Or the inventlon have the required physical properties that permit coatlng by the prererred gravure technlque without "plck orr" problems occurrlng;
that 18, wlthout causlng removal Or a portlon Or release - - , . , - ~ '-. ' lZ73~5~
layer 20 as the ink design layer 30 is coated thereon.
Release layer 20 also has the required properties that prevent embossing of the wax during printing of design layer 30 and also prevents ink striking into the wax during printing and ink migration into the wax after printing.
Release layer 20 is of a formulation which also prevents nonuniform splitting of the release layer during the heat transfer process and thereby prevents insufficient or uneven transfer of the release layer from the carrier web during the transfer process. In addition to having the requisite release property upon heating, release layer 20 also has sufficient adhesive properties upon cooling which keeps design layer 30 adhesively bonded to the article being imprinted and also forms a clear glossy protective coating layer over the transferred design layer 30. The clarity, smoothness, and glossiness of release layer 20 is improved by subjecting transfer substrate 15 to postflaming after substrate 15 has been transferred to an article. The postflaming may be accomplished by exposing the transferred substrate to jets of hot gas either as direct gas flame or as hot air jets for a period of time sufficient to remelt the wax, as for example by the methods described in U.S. patent 3,616,015. After postflaming layer 20 resolidifies quickly upon exposure to ambient conditions to form a smooth, glossy film of improved clarity. The resolidified layer exhibits so high a degree of clarity and translucency that there is virtually no visible halo or hazing either around or over the surface of the transferred design image 30. This results in remarkable clarity in the transferred design image. Thus, the laminate 5 is suitably applied to plastic and glass articles of a variety of shades, as well as to .....
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~2738Sl artlcles and contalne~rs composed Or optlcally clear plastlc materlals such as polyvlnylchlorlde and polyethylene terepthal&te or clear polyethylene or polypropylene. Prior art heat transrerable laminates, 5 although exhibitlng hlgh degree Or optlcal clarlty upon postrlaming, have some llmitation in application to optically clear plastics since there can be ~ome hazlng or halo discernible upon transrer onto optlcally clear materlals.
The virtual eliminatlon Or hazing or halo has been accompllshed while slmultaneously satisrying all other physlcal property requlrements rOr an errectlve release coatlng rOr a heat transrerable substrate as has been discussed ln the roregoing. Addltlonally thls lmprovement 1,5 has been made wlllle redu~lng the amount Or montan wax ln the preferred formulatlon. Slnce montan wax 1B a costly constltuent, appllcant has reallzed slgnlrlcant cost savlngs ln the preferred formulatlon ror release coatlng 20.
The preferred rormulatlon rOr relea~e layer 20 is a hot melt contalning pararfin and a montan wax which may also lnclude a minor amount Or mlcrocrystalline wax. In additldn to these waxes, the formulation includes a ta¢klrylng resln and sultable blnder. Appllcant has dlscovered ~ulte unexpectedly that, wlth proper selectlon Or tacklfler resln, the total amount Or crystalllnlty Or the parafrln wa% can be reduced slgnlrlcantly, more than would occur by addltlon Or other reslns or dlluents Or equal amount. It 18 not known wlth certalnty all of the ractors responslble for the hlgh degree Or clarlty and translucency Or the transrerred layer 20, but the reductlon ln lnherent crystalllne structure Or the pararrln wax aod to an extent the mlcrocrystalllne wax, as .
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lZ'73~3S
well, 18 believed to be the principal factor. Although it 18 known that the lnherent crystallinity of certain waxes, partlcularly pararfln wax, used in release coating ror heat transrerable laminates is a princlpal cau~e of the hazing erfect~ it has been heretorore not been posslble to reduce the crystalllnlty Or the solidiried wax without disrupting other lmportant physlcal propertles Or the release lager. Although postrlaming serves to reduce some Or the hazlng whi¢h appears over the transrerred lmage it erreats only a partial reductlon and does not decrease the crystallinlty o~ the wax components. Postflaming has been determined to lncrease clarlty prlnclpally because lt has the erfect Or smoothing mlcroscoplc hills and valleys on the surrace Or the transrerred release layer. Post~lamlng thus crea~es a smoother, more unirorm surrace Or glossy character, lncreases the overal~ clarity Or the transrerred release layer, and consequently the clarity of the transrerred deslgn image. Resldual amount Or opacity or ha~lng is believed to be caused bg the crystalllne structure Or the solidlried pararrin wa~ and to a lesser degree Or the ~olidlfled microcrystalline wax which contalns crystals Or much smaller size.
It i~ deslrable to select a thermoplastlc tacklrylng resln whlch is composed Or an optically clear, nonwax hydrocarbon polymer havlng a sortenlng polnt (Ball h ~ing Metkod ASTM E-28) between about 60C and 135C, more prererably between about 85C and 125C, and most prererably between about 100C and 125C. Appllcant has ~ound a partlcular polymer class Or thermopl~stlc reslns whlch when added to the release rormulatlon, lncrease the adhesiveness Or the release layer and qulte unexpectedly reduces the amount Or crystalllne structure ln the solldlrled wax. Thls reduction 18 greater than , , . -, : ' ' 12738Si mlght be expected from dilution Or the wax wlth otherresln~ or dlluents added in the same proportlon. The marked reduct~on in total crystalllnlty Or the wax, it ls theorlzed, enhances the optical clarity Or the wax upon resolldlricatlon. The solldlried release layer has a color ~ardner No. between about 1 and 4. The tackirying resln also prererably has a color Cardner number between about 1 and 4, typlcally between about 1 and 3.
The polymer class ror the tackifylng resln having the above-descrlbed properttes and determined to unexpectedly reduce the amount Or crystalllne ~tructure ln the solldiried wax 18 a transparent nonwa~ hydrogenated hydrocarbon resin. More specirioally, lt is the product Or a cycllo hydrocar~on monomer which has been polymerlzed and subsequently rully hydrogenated to completely saturate the polymer. Suitable cycllc hydrocarbon monomers which are polymerized and subsequently rully hydrogenated to rorm the tacklfylng resln component are prererably selected from C4 to C8 cycll¢ hydrocarbon monomers.
A prererred tacklfylng resln is rormed Or cyclopentadlene monomer whlch 18 polymerlzed and 8ubsequently rully hydrogenated. A tacklrylng resln Or thls latter type employlng cyclopentadlene monomer whlch 18 polymerl~ed and subseque~tly fully hydrogenated 18 avallable under the ESCOREZ serles reslhs rrom Ex~on Chemlcal Company. ~ preferred tacklrylng resin Or the ESCOREZ serles ls ESCOREZ 5300 resin. Thls resln has a water whlte color (Color aardner No. Or 3 or less); a Ball and Rlng sortenlng polnt Or about 105C; a speclrlc gravity (60/60F) Or 1.10; a Brookrleld vlscoslty (70 percent ln toluene at 60F) Or about 130 centlpol~e; and a fla~h polnt (COC) Or about 210C.
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12738Sl An alternative pr~ferred ESCOREZ re~in having a somewhat higher ~ortenlng point is ESCOREZ'5320 resln.
The latter resin has a water white color (Color aardner No. of 3 or less); a Ball and Ring sortening point Or about 125C; a speairlc gravlty (60/60~) Or 1 10; a Brookrield viscoslty (70 percent ln toluene at 60F) Or about 350 centipoise; and a rlash point (COC) ~r about 243C. ~n alternatlve p~eferred tackirying resin is a transparent nonwax hydrogenated hydrocarbon resin rormed Or styrene monomer which is polymerlzed and subsequently rully hydrogenated. A re~ln ~r thls latter type 18 avallable under the nEaAL~EZ tradename from llercules ,, Chemlcal Company. A speciflc REaAL~EZ resln round to be partlcularly suitable ror use as the tacklrylng re~ln ln the present lnvention 18 REa~LREZ 1126, whlch has a crystal clear color; a Ball and ~lng sortening point Or between about 122C to 130C; a speciric gravit,y at 21C Or o 97; an acld number Or less than 1-0; and a melt vlscosity Or 1 poise at 209C and 10 polse at 182C; and a rlashpolnt (COC) Or 243C.
The use Or a tacklrylng resin from the above-descrlbed classes ln appll¢ant's hot melt rormulation rOr wax release layer 20 has an addltlonal advantage over aonventlonal resins such as pentarerythrltol ester Or hydrogenated rosln used in prior art wax release formulatlorls. Such reslns may oxidlze over a period Or tlme causing a dulllng erfect ln the appearance Or the transrerred deslgn lmage. In contrast, the tacklrylng reslns employed ln the present rormulatlons for release 3~ layer 20 do not o~ldlze wlth tlme after the substrate 15 has been transrerred onto an artlcle.
The parafrin wax aomponent Or the formulation ror release layer 20 18 used to glve layer 20 lts pr,inclpal ..... . .
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lZ738~1 release characteristic upon meltlng. Pararrin wax, a petroleum derived product, typlcally ha~ a molecular welght between about 25l1 to 450 and i8 composed essentially Or linear saturated hydrocarbons ranging from C181~38 to C32ll66 Pararflns typlcally have a meltlng polnt from about 110 to 150F. ("Meltlng polnt"
as uced herein refer~ to drop melting point). A Preferred parafrin wax ror use in the rormulation Or the present lnvention is composed Or llnear saturated hydrocarbons ranglng from C26ll51l to C32~i66 havlng a meltlng polnt between about 145F to about 155F.
The pararrin wax, a llnear saturated hydrocarbon, ls characterlzed ln that lt crystalllzes in both plate and needle-type crystals, partlcularly the rormer. ~nother type Or crystalllne structure, termed malcrystalllne, 18 nelther plate nor needle-like and 18 observable ln the parafrln crystal structure ln amount dependlng on the bolllng polnt Or the pararfln rractlon belng lnvestlgated.
In parafrln wax rractlons Or lower bolllng point, for example about 1~0~ at 10 mm pressure, the entlre ¢rystalline structure is composed Or plates. ~n pararrln wax rractions having somewhat higher boillng points, a mlnor amount Or malcrystalllne and needle-llke structures mag be observable interspersed among the plate-llke structures. In general, the plate crystals predominate in pararrin waxes Or any bolllng range. Ilowever, ln the hlgher meltlng pararrln waxes where there is likely to be some increased amount of branchlng associated with their structure, there 18 llkelg to be a greater portlon Or malcrystalline and needle-like crystals lnterspersed among the plates. m e tgpe and amount Or crystals round ln parafrln wax is principally an inherent runction Or the boillng polnt range Or pararrlns being investigated lrrespective Or the solvent or medlum used from which the crystalllne solld 18 preclpltated.
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1~73851 Parar~in wax suitable for use ln release layer 20 18 sold in varlous grades which dlrfer chierIy in melting point. Commerclal grades Or parafrin wax whlch may be used in release layer 20 are commonly designated a~
rerlned~ semire~ined, and crude grade waxes. or these the rerlned grade i~ prererred for use in the present formulation rOr release layer 20. Parafrin wax Or rerlned grade is obtainable from a number Or source~, one Or which is the Petrolite Corp., Bareco DiYisionJ Or Tulsa, Oklahoma.
The miGrocrystalline component Or rormulatlon 20 is composed Or saturated hydro¢arbons Or higher melting point than those Or pararfln wax. Micro¢rystalline waxes chara¢teristlcally contain between about C341170 to C60~1120 hydro¢arbons having molecular weight between about 478 and 840. Microcrystalline waxes (mlcro-waxes) are characterized by an lncreased amount Or branchlng;
although they contain straight ohain molecules, they are - not as linear a saturated ~ydro¢arbon as pararrin wax.
Also compared to pararrin wax, they contain a greater portlon Or cyclic ring molecules. The crystalline structure Or the microcrystalllne wax contains predomlnantly malcrystalllne and needle-like crystals havlng very small underlned form when compared wlth the plate-llke crystalllne structure Or pararrin wax under the same magnificatlon. Thus the crystalllne structure Or mlcrocrystalline wax 18 small and irregular when ; solldlrled rrom the melted wax. In solvents mlcrocrystalllne wax dlscloses no well-rormed crystals Or any size. Small amounts Or mlcrowax are advantageously added to the formulatlon ror release layer 20, slnce mlcrQwax lmparts a measure Or plasticity to the pararrin wax componente, clnco tho pararrln wqx 1~ rather brlttle .
' and would by itself tend to cause cracks or fissures in a wax release layer. Because of its diminished crystalline structure, microwax contributes little potential hazing or halo effect.
The classes of microwaxes vary principally in their melting point range. For example, the so-called hard microwaxes have a melting point between about l9o to 210F; the plastic mircowaxes a melting point between about 145 to 175F; the emulsifiable crystalline waxes between about lso to 225F; and modified microwaxes between about 165 to 220F. All of these various types of microwaxes may be employed in the present formulation; however, the plastic type (BAREC0 designation) is most preferred. An illustrative, commercially available microcrystalline wax which is particularly suitable in the present formulation is available under the Victory White tradename from the Petrolite Corp.
The montan wax component for release layer 20 iS a coal (lignite) derived wax characterized by high concentration of montanic acid (C"H~60~). Montan wax has been determined to be a very suitable additive to increase the hardness of release coating 20, as well as its lubricity. Additionally, montan wax promotes a smooth glossy texture of the release coating after transfer. Montan wax also prevents penetration of the release coating into the paper carrier 10, as it forms a formation of a hard protective barrier coating over the transferred design layer.
A particularly suitable type of montan wax is an oxidized, esterified, partially saponified montan wax as disclosed in U.S. Patent 3,616,015. Montan waxes of this type have melting points (drop points) typically between about 50 and 110C, .
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saponiflcation value~ ~etween about 25 ~nd 150, acid values between about 5~ and 40, and penetrometer hardnes~
(ASTM-D5-52) below about 15 as measured with 100 grams for 5 second~ at 25C. The~e montan waxes also have 5 relatively hlgh melt vlscoslty. An lllustratlve oxldlzed, esteriried~ partlally saponlrled montan wax is avallable under the tradename ~loech~t OP or Hoech~t X55 modlried montan wax from the Hoechst Chemical Company, (location).
I50ech~t OP modlried montan wax has a drop polnt 10 (ASTM D12l) Or 212 to 221~, a congealing point (ASTM D938-49) between 165 and 175F, an acld number Or 1~ to 15, and a ~aponirication number Or 100 to 115.
Iloe¢hst X55 has a drop polnt of 20~ to 218F, a congealing polnt Or 167 to 176~, an acid number Or 10 15 to 15, and a saponlrlcation number Or 90 to 110. The~e waxes have melt viscoslties Or at least about 150 centlpolse at a temperature Or about 25F above thelr solldlricatlon point.
A partlcularly suitable blnder ln the preferred 20 release formulation i8 a copolymer Or ethylene and vlnyl~¢etate, such as that avallable under the tradename Elvax 410 ~rom E.I. duPont Company, Wllmlngton, DE. The blnder 18 used prlncipally to blnd the components Or the release rormulation trelease layer 20) ln a homogeneous 25 mlxture, whlch rorms a hot melt and does not require a solvent. The varlous components Or the release formulation do not copolymerl~e ln any measure durlng the coatlng stage or durlng meltlng and subsequent resolldlrlcatlon Or release layer 20. A blnder Or 30 copolymer Or ethylene and vinylacetate such as Elvax 410 18 most preferred because lt provldes hlgh optlmum gloss ln blends with wax. However, other blnders Or ethylene and vlnylacetate copolymer, as ror example, ~lvax 210, . . .
~Z73851 310, may be used. An alternative blnder in the ~LVAX
serles such as Elvax~4310 which 18 ethylene vlnylacetate acryllc acld terpolymer has also been determined to be sultable. Also ln place Or the above-referenced blnders acryllc acid terpolymer has also been determined to be an ethylene acryllc acld copolymer blnder may be employed.
A sultable blnder Or thls latter type 18 available under the tradename ~C-540 rrom Allled Chemical Company.
Prererred ¢omposltlons ror release layer 20 are shown ln Table I. Although spe¢lrl¢ rormulatlons rOr the release layer 20 are glven ln Table I, lt has been determlned that the pararrln wax may be present ln release layer 20 ln an amount between about 15 to 30 weight percent, prererably between about 20 to 25 welght percent.
me montan wax may be present ln release layer 20 ln an amount between about 15 to 35 welght percent, and the tacklrylng resln ln an amount between about 15 to 50 welght percent, prererably about 35 to 45 welght percent.
ffl e weight ratlo Or montan wax to tacklrylng resln may be ln a range between about 0.3/1 to 2.3/1.
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~'.' ~ ' ' '. ', , ~Z7~851 T A B L E
F~n~UL~ A B ~ ~
Wt. Wt. Wt. Wt.
Z % %
Pararrin Wax 22 22 22 22 Mlcrocrystalline Wax: (eg. BARECO
Vlctory White) 4 4 4 4 Montan Wax:
(eg. IJoe¢hst OP
or X-55) 27 27 27 27 Taaklrier Resln:
(~Iydrogena ted IJydroaarbon Polymer 15 --e.g. ESCOREZ 5300) 41 41 e.g. ESCOREZ 5320 41 e.g. REaALREZ 1126 41 Blnder:
(Ethyleile and Vlnyl-acetate aopolymer) ELV~X - 410 6 6 6 _ TOTAL 100 100 lOO lOO
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, ~ ny of the formulations of Table I can be prepared by addlng the llsted c~mponents in the proportlons shown to a sultable heatlng vessel and stirred thereln at a temperature of about 250 to 280F until a homogeneous hot melt mixture 18 obtained.
The hot melt is coated preferably by roller or gravure onto carrler 10 ln any desired slze and pattern, thus rormlng relea~e layer 20. When aoating wlth the prererred gravure technique, the thickness is convenlently adJusted by use Or proper gravure cyllnders. The thlckness Or coated release layer 20 is preferably less than about 0.001 lnch. Other coatlng technlque~ such as cast ¢oatlng, particularly reverse roller coatlng, letterpres3, and flexographlc techniques, mag be employed.
Arter coatlng release layer 20 onto carrier 10, the coating quickly becomes solidifled upon exposure to a water cooled roller. Upon solidlflcatlon Or release layer 20, an lnk deslgn layer 30 may be applied over thls layer typically using the same coating technique previously employed.
The lnk deslgn layer 30 18 preferably applled 80 that release layer 20 e~tends beyond the deslgn layer. The lnk deslgn layer 30 may be composed Or any conventlonal lnk Or any color. The ink may typically include reslnous blnder bases compatlble with the lnk plgment employed. The lnk blnder may be selected rrom a wlde varlety Or conventional reslnous bases such as polyamlde, polyvlnyl chloride, acryllcs, and polyamlde nltrocellulose.
It 18 advantageous to overlay lnk layer 30 wlth an adheslve coatlng 40 whlch racllitates transfer Or substrate 15 to the article to be de¢orated. In this case 1273~51 substrate 15 may there~ore typlcally be composed Or release layer 20, ink~design layer 30 and adhesive layer 40 as illustrated in Figure 2. Adheslve layer 40 may suitably be composed of a thermoplastlc polyaloide adhesive. A preferred thermoplastic polyamlde adheslve ls the reaction product Or a diamine wlth a dimerlzed ratty acid such as that available under the tradename VERSAMID
900 serles from Henkel Corp. Or Mlnneapolis, Minn. It has been found advantageous to combine thls polyamlde constltuent wlth a nltrocellulose base ln adheslve layer 10.
In use, carrler web 10 18 heated to a temperature typlcally rrom about 375 to 400P, i.e. surflcient to melt the release coatlng 20. Thls may be convenlently accomplished by conveylng lamlnate 5 over a hot platen ror a perlod surrlclent to melt release coatlng 20.
Alternatively the article to whlch lamlnate 5 is to be applled may be preheated to a temperature surriciently high to melt release layer 2n as laminate 5 is pressed agalnst the artlcle.
Lamlnate 5 is applled to the article to be decorated by presslng the heated lamlnate onto the article 80 that the topmost lager Or trRnsrer substrate 15, ror example lnk deslgn layer 30 or optional lager 40 contacts the artlcle. ~olllng pressure 18 applled over the exposed surrace Or carrler 10 to erfect transrer Or substrate 15 onto the article. m ereupon carrier 10 18 peeled from substrate 15 while release layer 20 is in molten state, leaving substrate 15 permanently arrlxed to the artlcle with design image clearly vlsible through transrerred release layer 20. Upon exposure to ambient conditlons for a short perlod, release coatlng 20 solidiries to a clear, :
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1~7~8Sl ~mooth glos~y protective layer over transrerred ink deslgn lmage 30.
The clarity Or the coatlng 20 over deslgn lmage 30 at thls polnt in the proceBB 18 dlstlnctly greater than the clarlty of the transferred release layer at the same polnt in the process as descrlbed ln U.S. Patent 3,616,015.
Transrerred substrate 15 may optionally be exposed to postrlamlng to remelt transrerred coating 20 and thus further improve the clarity and gloss of transrerred coating 20 and consequently clarlty Or transferred design image 30. Postrlaming may be accomplished, rOr example, by exposing the transrerred substrte 15 includlng transrerred coating 20 to Jets Or hot gas elther as dlrect ga~ rlame or as hot alr ~ets typlcally at about 300F to 400~ or hlgher ror a perlod surrl¢ient to melt the wax ln the manner deecribed in U.S. Patent 3,616,015. Upon exposure to amblent atmosphere, coatlng 20 resolidlrles to a rllm Or such high degree Or clarltg and transparency that hazing or halo errects are virtually undetectable by the unalded eye. The clarlty Or transrerred coating 20 and design image 30 is such that the heat transrerable substrate herein described may be used to decorate virtually any plastic or glass article. For example, the substrate 15 18 well suited to the decoration Or such materials as polyvinylchloride, polyethylene terephthalate, polyethylene, and polypropylene.
Although the lnvention has been described within the context Or particular embodiments for the transrerable substrate, the invention 18 not lntended to be limlted to any partlcular composltion or layer structure for the transrerable substrate. It 18 known that the transrerable subetrato may contaln other co~tlng lnyer~, for e~mple, - ' ' , - -, -, 1;~73~Sl a plurallty Or lnk deslgn layers or separate adhesive layer over the ink design layer as well as barrier type layers between the ink deslgn layer and release layer.
The inventlon is equally applicable to such varying heat transrerable ~tructures. It should be appreciated that the release rormulation Or the inventlon has wide appll¢ation as a release coating for any heat transrerable subetrate ln aontact with a support member such as a carrier web. The lnventlon, thererore, 18 not lntended to be limlted to the de~cription in the ~pecification but rather is derined by the claims and equivalent~ thereof.
Claims (11)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A heat transferable laminate of the type comprising a substrate affixed to a support member for transfer from said support member to an article upon application of heat to said support member while said article is in contact with said substrate, said substrate comprising in sequence a release layer in contact with the support member and an ink design layer over the release layer, said release layer comprising in combination:
a paraffin wax composed of linear saturated C18 to C12 hydrocarbons having a melting point between about 110°F and 150°F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60°C and 135°C, oxidation resistance under ambient conditions, and has Color Gardner Nos. of between about 1 and 4.
a paraffin wax composed of linear saturated C18 to C12 hydrocarbons having a melting point between about 110°F and 150°F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60°C and 135°C, oxidation resistance under ambient conditions, and has Color Gardner Nos. of between about 1 and 4.
2. A heat transferable laminate as in Claim 1 wherein the tackifying polymer is the product of cyclic hydrocarbon monomer polymerized and subsequently fully hydrogenated after said polymerization.
3. A heat transferable laminate as in Claim 1 wherein the tackifying polymer is the product of C4 to C8 cyclic hydrocarbon monomer polymerized and subsequently fully hydrogenated after said polymerization.
4. A heat transferable laminate as in Claim 3 wherein said cyclic monomer comprises cyclopentadiene.
5. A heat transferable laminate as in Claim 3 wherein said cyclic monomer comprises styrene.
6. A heat transferable laminate as in Claim 1 wherein the release layer further comprises a resin binder selected from the group consisting of ethylene-vinyl acetate copolymer and ethylene vinyl acetate acrylic acid terpolymer.
7. A heat transferable laminate as in Claim 1 wherein the paraffin wax comprises between about 15 to 30 percent by weight of said release layer, the montan wax comprises between about 15 to 35 percent by weight of said release layer, and the tackifying polymer comprises between about 15 to 50 percent by weight of said release layer.
8. A heat transferable laminate as in Claim 1 wherein the weight ratio of montan wax to tackifying polymer is in the range between about 0.3/1 to 2.3/1.
9. A heat transferable laminate of the type comprising a substrate affixed to a support member for transfer from said support member to an article upon application of heat to said support member while said article is in contact with said substrate, said substrate comprising in sequence a release layer in contact with the support member and an ink design layer over the release layer, said release layer comprising in combination:
a paraffin wax composed of linear saturated C18 to C32 hydrocarbons having a melting point between about 110°F and 150°F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60°C and 135°C, oxidation resistance under ambient conditions, and has Color Gardner Nos. of between about 1 and 4, and wherein said paraffin wax comprises between about 15 to 30 percent by weight of said release layer, the montan wax comprises between about 15 to 35 percent by weight of said release layer, and the tackifying polymer comprises between about 15 to 50 percent by weight of said release layer.
a paraffin wax composed of linear saturated C18 to C32 hydrocarbons having a melting point between about 110°F and 150°F, a montan wax that is oxidized, esterified, and partially saponified, and a thermoplastic tackifying polymer chosen from the group of transparent, nonwax hydrogenated hydrocarbon polymers having softening points between about 60°C and 135°C, oxidation resistance under ambient conditions, and has Color Gardner Nos. of between about 1 and 4, and wherein said paraffin wax comprises between about 15 to 30 percent by weight of said release layer, the montan wax comprises between about 15 to 35 percent by weight of said release layer, and the tackifying polymer comprises between about 15 to 50 percent by weight of said release layer.
10. A heat transferable laminate as in Claim 9 wherein the tackifying polymer is the product of cyclic hydrocarbon monomer polymerized and subsequently fully hydrogenated after said polymerization.
11. A heat transferable laminate as in Claim 9 wherein the tackifying polymer is the product of C4 to C8 cyclic hydrocarbon monomer polymerized and subsequently fully hydrogenated after said polymerization.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000492960A CA1273851A (en) | 1985-10-15 | 1985-10-15 | Heat transferable laminate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000492960A CA1273851A (en) | 1985-10-15 | 1985-10-15 | Heat transferable laminate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1273851A true CA1273851A (en) | 1990-09-11 |
Family
ID=4131624
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000492960A Expired - Lifetime CA1273851A (en) | 1985-10-15 | 1985-10-15 | Heat transferable laminate |
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| Country | Link |
|---|---|
| CA (1) | CA1273851A (en) |
-
1985
- 1985-10-15 CA CA000492960A patent/CA1273851A/en not_active Expired - Lifetime
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |