CA1056653A - Color-coded identifier microparticles - Google Patents
Color-coded identifier microparticlesInfo
- Publication number
- CA1056653A CA1056653A CA263,249A CA263249A CA1056653A CA 1056653 A CA1056653 A CA 1056653A CA 263249 A CA263249 A CA 263249A CA 1056653 A CA1056653 A CA 1056653A
- Authority
- CA
- Canada
- Prior art keywords
- colored layers
- microparticles
- laminate
- improvement
- particles
- 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
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/74—Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/06009—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code with optically detectable marking
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K2019/06215—Aspects not covered by other subgroups
- G06K2019/06225—Aspects not covered by other subgroups using wavelength selection, e.g. colour code
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K2019/06215—Aspects not covered by other subgroups
- G06K2019/06234—Aspects not covered by other subgroups miniature-code
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Theoretical Computer Science (AREA)
- Laminated Bodies (AREA)
- Credit Cards Or The Like (AREA)
Abstract
ABSTRACT
An improved process for manufacturing color-coded indetifier microparticles is disclosed. Accord-ing to the process a laminate comprising colored layer in a predetermined color sequence to constitute a code is randomly broken up into irregularly shaped microparticles wherein the outer surfaces of the colored layers at the extremities of the code are parallel to each other and the largest dimension of the microparticles is greater than he distance between the parallel surfaces.
An improved process for manufacturing color-coded indetifier microparticles is disclosed. Accord-ing to the process a laminate comprising colored layer in a predetermined color sequence to constitute a code is randomly broken up into irregularly shaped microparticles wherein the outer surfaces of the colored layers at the extremities of the code are parallel to each other and the largest dimension of the microparticles is greater than he distance between the parallel surfaces.
Description
~t~5~
This invention rclates to an improved process for manufacturing color-coded identifier mlcroparticles. Another aspcct of the invention relates to improved color-coded mlcroparticles manufactured by ~he process.
These microparticles are useful in tagging substances for the purpose of retrospective indentiflca~ion of the substance.
The use o microparticles bearing coded information to tag sub-stances for the purpose of retrospective identlfication is known. United States Patents 3,772,200 and 3,897,284 des~ribe microspheres containing trace elements in various comblnations and concentrations constituting identifying codes. Decoding entails the use of sophisticated analytical instruments such as an electron microprobe analyzer.
More convenient decoding is possible by using color-coded identifier microparticles wherein the identifYing code is pro~ided by sequential arrange-ment of visually distinguishable colors. The code can be read with an in-eXpensive micr~scope or magnifying glass. Color-coded identifier micro-particles of this type are described in United States patent 4,053~433.
These microparticles are primarily of unifrom geometric shape, normally being either spherical~ cylindrlcal or rectangular. Processes disclosed in this United States patent for producing these microparticles are inherently rather expensi~e.
~t~ 3 The ~resent ~.nventioll provides~ colo~-coded ldenti~ler mlcro-particles whic~ are economical ~o manu:~acture. :, In particular, accordlng to tlle present inventlon there is provided:in a plurality of batches of microparticles useful for tagging substances to permit retrospectlve identifica-tion, wherein microparticles o each batch are uniformly and uniquely encoded with an orderly sequential arrangement of at least three v~sually distinguishable colored layers and each microparticle measures 15 to 1,000 micrometers across the color sequence~ the improvement comprising: the external surfaces o the colored layers at the extremities - :~ .
of the code of each microparticle are generally flat and parallel to each other and its other surfaces have irregular, broken shapes, the broadest . dimension of most of the partlcles being greater than the distance between said parallel surfaces. ~:
According to another aspect of the present invention there is provided a process for preparing irregularly-shaped, color coded identifier particles comprising: combining at least three visually distinguishable colored layers in a predetermined color sequence to form a laminate having a :
.' thickness of 15 to 1,000 micrometers; randomly breaking up the laminate into microparticles encoded by an orderly sequential arrangement of colored layers so that the external surfaces of the colored layers at the extremities of the ` code of each microparticle are generally flat and parallel to each other and ~:
its other surfaces ha~e irregular, broken shapes, the broadest dimension of most o~ the particles being greater than the distance between said parallel ~ .
surfaces.
Accord~ng to the process of the invention as.referred to above, at .: least three v~sually dist~ngulshable colored layers of a film-forming substance arq co~b~ned in a predetermined color se~uence to ~orm a laminate having a th~c~ness of 15 to 1000 mlcro~eters. The laminate is randomly broken up into micropart~cles, the broadest dimension of most of which is somewhat greater ' 30 than the thickness o~.the laminate. These m~croparticles dif~e~ ~om those . .descri~ed ln United States Patent 4,053,433 by their novel geometric con--~lgurat~on. That is,.the external suraces of the code of each microparticle ,' g;~' .,.
" -are generally flat and parallel to each o-the~ and lts other sur~ac~s have irreguklr, broken sTIapes.
In a preferred embod~ment of the process of the ~nvention, the colored layers are ind.tvidually deposited ln l~uicl form upon a releasable carrier sheet and sequentlally hardened or drled to a solid state to provide a lc~minate which is removed ~rom the carrier sheet and then co~ninuted int microparticles. Alternatlvely, pre-formed colored layers, such as may be individually ~ormed by extrusion~ are combined into a laminate as, for examplel in a heated platen press.
A wide variety of materials may be used to form the colored layers of the microparticles. The preferred materials are rapid-curlng organic resins whtch when cured are brittle at room temperature. Melamine resins such as melamine alkyds and melamine acrylates are e:pecially preferred.
:
~ ' , _ 2a ~
,~'' Or~anic resins whlch ~orm ~heets whl~h are brittle only when cooled~ such a~ cellulo~e acetate butyrate or polyethylenej may also be used to form the colored layers o~ the mlcroparticlesO However, the cost o~ coo}ing ~uch materials during commlnution may llmit their utillty.
Inorganic materlals such as sodium sllicate are also useful.
The color o~ each layer is generally provided by the addition of dye or pigment prlor to forming the layerO
Clear or colorle~s layers may also form part o~ the lden-tifying codeO Pigments producing opaque colored layers are pre~erred over dyes which tend to produce transparent layersO
The demarcation between layers ls less apparent when the layers transmit llght. Dyes3 when added to a white pigment such as titanium dioxide~ produce desirably opaque colors.
In addition to us~ng colors which are re-~ponsive to visual light9 ~luorescent and phosphorescent material~ which are responsive to ultravlolet light may be lncorporated into the code and may provide an additional ~unctionO For example~ an explosive may be tagged wlth microparticles having a ~luorescent color on one of the outermost seg~ents. A~ter detonation9 the blast debrls may be llluminated with an ultraviolet llght source to provide a quick lndication~ e~gO9 that the explosive wa~
or was not manufactured in aocordance with speci~ic government regulations, namely permis~ible or non~permissible explosive~O
Upon retrieva1 o~ the microparticles the color code may be read to a~certain such ln~ormation a~ manu~acturer and lot , numberO
.
~ 3 ~
:~35~3 It Ls preferred in some cases to incorporate magnetic material into one or more layers of the micro-particles~ This is partlcularly desirable when bulk materials or explosives are taggedO RetrLev~1 of magnetic microparticles ls enhanced by the use of a magnet~
Magnetic materlal may be heavily con centrated in a single layer~ ln which case the color o~ the `
magnetic material may determine the color o~ the layerO
Alternatively~ a small amount o~ magnetic ma~erial may be incorporated into each layer without 5igni~icantly af~ecting the color o~ individual layersO Generally9 the magnetic material may be added in an amount of up to one hal~ the weight of the pigment or dye without masklng the color of the layerO
When using liqulds to create the laminate ~rom which the novel microparticles are broken9 it is pre~
~erred to harden or cure each layer partially before the next layer is appliedO This prevents the fresh layer from attacking the underlying layer to cause the colors to run togetherO The laminate is generally completely hardened or cured priur to bein~ broken up into mlcropar~icles~
Using conventional coating techniques9 the preferred th1ckness o~ each layer ls about 5 to 50 micro~
metersO Layers thicker than 5 micrometers are generally ea~y to read wit~out a h~gh degree o~ magn~icationO ~ayers thicker than 50 micromebers simply result in economlc wasteO
~he number o~ layers ln each code may range rrom a mln~mum o~ three to a maximum number which is llmlted only by the overall size requirements o~ the microparticlesO Micro~
particles greater than 1000 micrometers at their broadest , .. 1~ ~
~s~
dimension tend to be noticable to the naked eye~ and as a result, thelr utility for most tagglng purpo~es is limitedO
In order to insure that a microparticle ; having a complete code is retrieved and idenklfled 9 it i8 desirable to tag articles or substances which must be dis~
tinguished from each other with micropart~cles having the same number of layers. For example, exploslves may be uni~ormly tagged with six~layered microparticles 9 each having a magnetic layer as one o~ the outermost layers of the ; 10 particleO When a microparticle ls retrieved ~rom the blast debri~l the number of layers can be counted. If less than six layers are present~ the microparticle should be discarded as being incomplete and a microparticle bearing a complete code selectedO
In the laboratory~ ~ragmentation of the laminate is most e~ective~y accomplished by uslng a high ` speed blender with alr suspension o~ the laminateO It has also been ~ound that llquid suspension of the laminate during the ~ragmentatlon step results in the formation o~ a 1 20 greater proportion o~ microparticles ln the desired slze ; rangeO However~ the addition of a liquid tends to increase the overall cost of manu~ackure.
A ball mill may also be used to break up the laminateO However~ a larger proportion o~ incomplete codes i~ produced by this methodO `
Prior ~o size classifLcat-Lon Or the fragmented material~ it m~ay be washed and driedO During the wa~hlng step some of the underslzed ~dust~ partic~es are suspended and ! ~ removed by decankationO The remaining material may be classi~ied by screening or sieving and dlvided into three ~ (35~S3 groups~ (a) Particles whose largest dlmension i8 greater than ~our times the distance between the outer surfaces of the two outer code layers. These should be further fra~mented.
(b) Part~cles whose largest dimension is from one to four l ;
times the dlstance between the outer surfaces of the two outer code layers~ Most of these include the full code and are pre~erred for tagging. (c) Particles whose largest dimen~ion is less than the length of the color codeO These chould be discarded.
It has been found that the microparticles of the invention are particularly userul for tagging art ob;ects~ bondsa certi~icates and similar items where counter;
feitlng ls a problem. For this purpose the microparticles may be incorported into a clear lacquer which is applied to an incon~picuous place on the ob~ect.
When tagglng liquid substancesg the denslty of the microparticles should approximate the denslty o~ the llquid in order to maintaln them in suspensionO The density o~ the microparticles may be controlled by well known means such as by incorporating glass bubbles to form colored isotactic foam layers~
To provide a secondary means of identifica~
tion~ and additlonal coded information9 coded microparticles ~ `~
such as those described in U.S. Pa~ent 39772,200 may be incorporated into one or more colored layersO This would inhibit counter~eiting of the color coded microparticles ,~ themselvesO Additionallyg it may be desirable to tag a substance with microparticles bearing different codesO For example9 ~wo=layered microparticles may be included along ` 30 with three layered micrQparticles. In that case both types ,, :
6 ~
.. . . ~ . : -:~0S~3 of ~icropartlcles mu~ be isolated and read~
The drawlngs illustrate a perspecti~e view3 of three identi~ler micropart~cles o~ the lnventionO
Micropart:Lcle 10 consLst~ of ~ix colored layers 12 ln a preselected color sequence to constitute an identi.~ying codeO ~he external surfaces 14 and 16 o~ the colored segments are parallel to each other~ ~he other sur~
~aces of the partlcle have irregular~ broken shapes, The broadest dimenslon of the p~rtlcle lles across surfaces 14 and 16~ and this dimension is greater than the distance between the parallel surfaces~ :
Mlcropartlcle 20 shows that hlghly irregular shapes may be useful in khe inventionO
Microparticle 30 has magnekic material incorporated into the colored layers 320 The particle is shown oriented on a piece of paper wlth a magnet so positloned below the paper thak its lines of magnetic ~lux ar~ perpendicular to the paperO This causes ~he par~lcle to stand on edge ~o that the color sequence can bs e~sily readO
The ~ollow~ng non llmitlng examp~es further ~llustrate the in~entiono _XAMPLE 1 Micrsparticles were formed ~rom melamine alkyd re~in wherein one of -the outermoæt colored segments of the code ls ~luorescent red and the other contalns magnetlc materialO
A resin ~ase was prepared by mixing together 25 grams of a 50 percent solid~ soya alkyd resin in xylene9 25 grams o~ a 55 percent ~ollds alkylated me~amine in butanol .. . . . ~ .
and xylene~ and 0~5 gO o~ 20 percent para~toluene sulfonlc acid in isopropanolO
The rollowing four coating mlxture3 were each prepared by adding to 5005 gO o.~ resin base the ~ollow~
ing addltlveso Coating Mlxture Additive Amount A Fluorescent Red dye ln polysulfonamide re~in 805 gO
B Rutile titanlum dioxide pigment 900 gO
C Qulnacridone red dye 3-0 gO
Red iron oxlde plgment 20 0 gO
D Carbonyl iron powder 60 7 gO
Colloidal silica lo 0 go These coating mlxtures were coated on a polyester carrier film ( o O02 inO 9 5008 micrometers~ with a ~ `
wire wound rod in the sequence shown below :i Coat A B C B C B D ~ :
Dry thlck~
~ 20 ness ~mils) o8 o3 o2 o3 ~2 o3 105 i (Mlcro meters~ (2003~ t706) (501~ ~7.6~(501) ~706~ ~38~1 ~he thickness of the seven combined layers was o0036 inch9 t9104 mlcrometer~. A~te-r each layer was applled it wa~
heated ~or 15 sec-ond~ at 140 C~ After the last layer was applled the laminate ~s heated at 140~ C. for 10 minute~
to obtain a full cure o~ the alkyd~melamine reslnO
:, ~he laminate was placed in a dry blender whlch wa~ oper,ated ~or about 20 second~O
;
..
EXAMPL~ 2 Micropartic les o~ sodiu.m sil1 cate were pre~
pared from the ~ollowing three coatlng mixtures, Coating Mixture ~g~ nts Amount A Sodium Si.licate 70 g~
Blue pigment 7 gO
Wat er 3 g~ :
B Sodium Silicate 70 White pigment (Titanium dioxide) 7 gO
Water 4 ~0 C Sodium Silicate 70 gO
Carbonyl iron 30 gO
The coating mixtures were applled to a oOOl inoh (about 25~4 microns) aluminized polyester carrier film ~ith a wire wound rod in the following SeqUenCeJ
B~A B~A;~;B~A-Co The layers were placed on the aluminized side o~ the carrier ~ilm to prevent beading o~ the first layerO Each layer was allowed to dry in an oven for a few seconds at 70 C. be~ore the next coat was appliedO
After the last layer was applied a piece o~ :~
the laminate was dried for a ~ew mlnutes at 70~ CO and then removed from ~he carrier film by ~lexing the polyester ~harplyO The laminate~ which was white on one slde and black on the other side9 was still somewhat flexibleO It was dried at lO0~ C. ~or a ~ew minutes to make it brittle9 at which point it was easil~ broken into micropartlcles by a -~
blender as de~cr:lbed in example lo Another piece o~ the laminate was dried ~or about lO minutes at lO0~ C0 The laminate became very brittleO
, ; -.. . . .................... . . . ......... .
, , . ~ . ~ . : . :. .
The lamlnate was then removed by rlexin~ the polyester sharplyO In this case the aluminum from the carrier ~llm vapor coat adhered to the lamlnate so l;hat the m:lcroparticles ~ were black on one side and had an alumiLnum mirror on the ; 5 other sldeO When the micropartlcles were viewed on edge9 the colored layers were seen easily~ but the aluminum was too thin to be seen edgewlse at lOOX magni~icatlon. Nevertheless9 because it could be seen from the side~ it might be con~
sidered as part o~ the codeO
When the microparticles are immersed in water9 they tend to re-dissolve withln a few hoursO They can be made insoluble by immersion in a solution of a metal ; ~;
salt which will replace the sodium in the sodium sillcate with a metal whose silicate is insoluble in waterO For example, immersion of the particles for 24 hours in a 20 percent aqueous solution of aluminum sul~ate (Al2(S04~3018H20 will make the particles insoluble in ~ater o~ pH 80 ~.
~ 10 ~
This invention rclates to an improved process for manufacturing color-coded identifier mlcroparticles. Another aspcct of the invention relates to improved color-coded mlcroparticles manufactured by ~he process.
These microparticles are useful in tagging substances for the purpose of retrospective indentiflca~ion of the substance.
The use o microparticles bearing coded information to tag sub-stances for the purpose of retrospective identlfication is known. United States Patents 3,772,200 and 3,897,284 des~ribe microspheres containing trace elements in various comblnations and concentrations constituting identifying codes. Decoding entails the use of sophisticated analytical instruments such as an electron microprobe analyzer.
More convenient decoding is possible by using color-coded identifier microparticles wherein the identifYing code is pro~ided by sequential arrange-ment of visually distinguishable colors. The code can be read with an in-eXpensive micr~scope or magnifying glass. Color-coded identifier micro-particles of this type are described in United States patent 4,053~433.
These microparticles are primarily of unifrom geometric shape, normally being either spherical~ cylindrlcal or rectangular. Processes disclosed in this United States patent for producing these microparticles are inherently rather expensi~e.
~t~ 3 The ~resent ~.nventioll provides~ colo~-coded ldenti~ler mlcro-particles whic~ are economical ~o manu:~acture. :, In particular, accordlng to tlle present inventlon there is provided:in a plurality of batches of microparticles useful for tagging substances to permit retrospectlve identifica-tion, wherein microparticles o each batch are uniformly and uniquely encoded with an orderly sequential arrangement of at least three v~sually distinguishable colored layers and each microparticle measures 15 to 1,000 micrometers across the color sequence~ the improvement comprising: the external surfaces o the colored layers at the extremities - :~ .
of the code of each microparticle are generally flat and parallel to each other and its other surfaces have irregular, broken shapes, the broadest . dimension of most of the partlcles being greater than the distance between said parallel surfaces. ~:
According to another aspect of the present invention there is provided a process for preparing irregularly-shaped, color coded identifier particles comprising: combining at least three visually distinguishable colored layers in a predetermined color sequence to form a laminate having a :
.' thickness of 15 to 1,000 micrometers; randomly breaking up the laminate into microparticles encoded by an orderly sequential arrangement of colored layers so that the external surfaces of the colored layers at the extremities of the ` code of each microparticle are generally flat and parallel to each other and ~:
its other surfaces ha~e irregular, broken shapes, the broadest dimension of most o~ the particles being greater than the distance between said parallel ~ .
surfaces.
Accord~ng to the process of the invention as.referred to above, at .: least three v~sually dist~ngulshable colored layers of a film-forming substance arq co~b~ned in a predetermined color se~uence to ~orm a laminate having a th~c~ness of 15 to 1000 mlcro~eters. The laminate is randomly broken up into micropart~cles, the broadest dimension of most of which is somewhat greater ' 30 than the thickness o~.the laminate. These m~croparticles dif~e~ ~om those . .descri~ed ln United States Patent 4,053,433 by their novel geometric con--~lgurat~on. That is,.the external suraces of the code of each microparticle ,' g;~' .,.
" -are generally flat and parallel to each o-the~ and lts other sur~ac~s have irreguklr, broken sTIapes.
In a preferred embod~ment of the process of the ~nvention, the colored layers are ind.tvidually deposited ln l~uicl form upon a releasable carrier sheet and sequentlally hardened or drled to a solid state to provide a lc~minate which is removed ~rom the carrier sheet and then co~ninuted int microparticles. Alternatlvely, pre-formed colored layers, such as may be individually ~ormed by extrusion~ are combined into a laminate as, for examplel in a heated platen press.
A wide variety of materials may be used to form the colored layers of the microparticles. The preferred materials are rapid-curlng organic resins whtch when cured are brittle at room temperature. Melamine resins such as melamine alkyds and melamine acrylates are e:pecially preferred.
:
~ ' , _ 2a ~
,~'' Or~anic resins whlch ~orm ~heets whl~h are brittle only when cooled~ such a~ cellulo~e acetate butyrate or polyethylenej may also be used to form the colored layers o~ the mlcroparticlesO However, the cost o~ coo}ing ~uch materials during commlnution may llmit their utillty.
Inorganic materlals such as sodium sllicate are also useful.
The color o~ each layer is generally provided by the addition of dye or pigment prlor to forming the layerO
Clear or colorle~s layers may also form part o~ the lden-tifying codeO Pigments producing opaque colored layers are pre~erred over dyes which tend to produce transparent layersO
The demarcation between layers ls less apparent when the layers transmit llght. Dyes3 when added to a white pigment such as titanium dioxide~ produce desirably opaque colors.
In addition to us~ng colors which are re-~ponsive to visual light9 ~luorescent and phosphorescent material~ which are responsive to ultravlolet light may be lncorporated into the code and may provide an additional ~unctionO For example~ an explosive may be tagged wlth microparticles having a ~luorescent color on one of the outermost seg~ents. A~ter detonation9 the blast debrls may be llluminated with an ultraviolet llght source to provide a quick lndication~ e~gO9 that the explosive wa~
or was not manufactured in aocordance with speci~ic government regulations, namely permis~ible or non~permissible explosive~O
Upon retrieva1 o~ the microparticles the color code may be read to a~certain such ln~ormation a~ manu~acturer and lot , numberO
.
~ 3 ~
:~35~3 It Ls preferred in some cases to incorporate magnetic material into one or more layers of the micro-particles~ This is partlcularly desirable when bulk materials or explosives are taggedO RetrLev~1 of magnetic microparticles ls enhanced by the use of a magnet~
Magnetic materlal may be heavily con centrated in a single layer~ ln which case the color o~ the `
magnetic material may determine the color o~ the layerO
Alternatively~ a small amount o~ magnetic ma~erial may be incorporated into each layer without 5igni~icantly af~ecting the color o~ individual layersO Generally9 the magnetic material may be added in an amount of up to one hal~ the weight of the pigment or dye without masklng the color of the layerO
When using liqulds to create the laminate ~rom which the novel microparticles are broken9 it is pre~
~erred to harden or cure each layer partially before the next layer is appliedO This prevents the fresh layer from attacking the underlying layer to cause the colors to run togetherO The laminate is generally completely hardened or cured priur to bein~ broken up into mlcropar~icles~
Using conventional coating techniques9 the preferred th1ckness o~ each layer ls about 5 to 50 micro~
metersO Layers thicker than 5 micrometers are generally ea~y to read wit~out a h~gh degree o~ magn~icationO ~ayers thicker than 50 micromebers simply result in economlc wasteO
~he number o~ layers ln each code may range rrom a mln~mum o~ three to a maximum number which is llmlted only by the overall size requirements o~ the microparticlesO Micro~
particles greater than 1000 micrometers at their broadest , .. 1~ ~
~s~
dimension tend to be noticable to the naked eye~ and as a result, thelr utility for most tagglng purpo~es is limitedO
In order to insure that a microparticle ; having a complete code is retrieved and idenklfled 9 it i8 desirable to tag articles or substances which must be dis~
tinguished from each other with micropart~cles having the same number of layers. For example, exploslves may be uni~ormly tagged with six~layered microparticles 9 each having a magnetic layer as one o~ the outermost layers of the ; 10 particleO When a microparticle ls retrieved ~rom the blast debri~l the number of layers can be counted. If less than six layers are present~ the microparticle should be discarded as being incomplete and a microparticle bearing a complete code selectedO
In the laboratory~ ~ragmentation of the laminate is most e~ective~y accomplished by uslng a high ` speed blender with alr suspension o~ the laminateO It has also been ~ound that llquid suspension of the laminate during the ~ragmentatlon step results in the formation o~ a 1 20 greater proportion o~ microparticles ln the desired slze ; rangeO However~ the addition of a liquid tends to increase the overall cost of manu~ackure.
A ball mill may also be used to break up the laminateO However~ a larger proportion o~ incomplete codes i~ produced by this methodO `
Prior ~o size classifLcat-Lon Or the fragmented material~ it m~ay be washed and driedO During the wa~hlng step some of the underslzed ~dust~ partic~es are suspended and ! ~ removed by decankationO The remaining material may be classi~ied by screening or sieving and dlvided into three ~ (35~S3 groups~ (a) Particles whose largest dlmension i8 greater than ~our times the distance between the outer surfaces of the two outer code layers. These should be further fra~mented.
(b) Part~cles whose largest dimension is from one to four l ;
times the dlstance between the outer surfaces of the two outer code layers~ Most of these include the full code and are pre~erred for tagging. (c) Particles whose largest dimen~ion is less than the length of the color codeO These chould be discarded.
It has been found that the microparticles of the invention are particularly userul for tagging art ob;ects~ bondsa certi~icates and similar items where counter;
feitlng ls a problem. For this purpose the microparticles may be incorported into a clear lacquer which is applied to an incon~picuous place on the ob~ect.
When tagglng liquid substancesg the denslty of the microparticles should approximate the denslty o~ the llquid in order to maintaln them in suspensionO The density o~ the microparticles may be controlled by well known means such as by incorporating glass bubbles to form colored isotactic foam layers~
To provide a secondary means of identifica~
tion~ and additlonal coded information9 coded microparticles ~ `~
such as those described in U.S. Pa~ent 39772,200 may be incorporated into one or more colored layersO This would inhibit counter~eiting of the color coded microparticles ,~ themselvesO Additionallyg it may be desirable to tag a substance with microparticles bearing different codesO For example9 ~wo=layered microparticles may be included along ` 30 with three layered micrQparticles. In that case both types ,, :
6 ~
.. . . ~ . : -:~0S~3 of ~icropartlcles mu~ be isolated and read~
The drawlngs illustrate a perspecti~e view3 of three identi~ler micropart~cles o~ the lnventionO
Micropart:Lcle 10 consLst~ of ~ix colored layers 12 ln a preselected color sequence to constitute an identi.~ying codeO ~he external surfaces 14 and 16 o~ the colored segments are parallel to each other~ ~he other sur~
~aces of the partlcle have irregular~ broken shapes, The broadest dimenslon of the p~rtlcle lles across surfaces 14 and 16~ and this dimension is greater than the distance between the parallel surfaces~ :
Mlcropartlcle 20 shows that hlghly irregular shapes may be useful in khe inventionO
Microparticle 30 has magnekic material incorporated into the colored layers 320 The particle is shown oriented on a piece of paper wlth a magnet so positloned below the paper thak its lines of magnetic ~lux ar~ perpendicular to the paperO This causes ~he par~lcle to stand on edge ~o that the color sequence can bs e~sily readO
The ~ollow~ng non llmitlng examp~es further ~llustrate the in~entiono _XAMPLE 1 Micrsparticles were formed ~rom melamine alkyd re~in wherein one of -the outermoæt colored segments of the code ls ~luorescent red and the other contalns magnetlc materialO
A resin ~ase was prepared by mixing together 25 grams of a 50 percent solid~ soya alkyd resin in xylene9 25 grams o~ a 55 percent ~ollds alkylated me~amine in butanol .. . . . ~ .
and xylene~ and 0~5 gO o~ 20 percent para~toluene sulfonlc acid in isopropanolO
The rollowing four coating mlxture3 were each prepared by adding to 5005 gO o.~ resin base the ~ollow~
ing addltlveso Coating Mlxture Additive Amount A Fluorescent Red dye ln polysulfonamide re~in 805 gO
B Rutile titanlum dioxide pigment 900 gO
C Qulnacridone red dye 3-0 gO
Red iron oxlde plgment 20 0 gO
D Carbonyl iron powder 60 7 gO
Colloidal silica lo 0 go These coating mlxtures were coated on a polyester carrier film ( o O02 inO 9 5008 micrometers~ with a ~ `
wire wound rod in the sequence shown below :i Coat A B C B C B D ~ :
Dry thlck~
~ 20 ness ~mils) o8 o3 o2 o3 ~2 o3 105 i (Mlcro meters~ (2003~ t706) (501~ ~7.6~(501) ~706~ ~38~1 ~he thickness of the seven combined layers was o0036 inch9 t9104 mlcrometer~. A~te-r each layer was applled it wa~
heated ~or 15 sec-ond~ at 140 C~ After the last layer was applled the laminate ~s heated at 140~ C. for 10 minute~
to obtain a full cure o~ the alkyd~melamine reslnO
:, ~he laminate was placed in a dry blender whlch wa~ oper,ated ~or about 20 second~O
;
..
EXAMPL~ 2 Micropartic les o~ sodiu.m sil1 cate were pre~
pared from the ~ollowing three coatlng mixtures, Coating Mixture ~g~ nts Amount A Sodium Si.licate 70 g~
Blue pigment 7 gO
Wat er 3 g~ :
B Sodium Silicate 70 White pigment (Titanium dioxide) 7 gO
Water 4 ~0 C Sodium Silicate 70 gO
Carbonyl iron 30 gO
The coating mixtures were applled to a oOOl inoh (about 25~4 microns) aluminized polyester carrier film ~ith a wire wound rod in the following SeqUenCeJ
B~A B~A;~;B~A-Co The layers were placed on the aluminized side o~ the carrier ~ilm to prevent beading o~ the first layerO Each layer was allowed to dry in an oven for a few seconds at 70 C. be~ore the next coat was appliedO
After the last layer was applied a piece o~ :~
the laminate was dried for a ~ew mlnutes at 70~ CO and then removed from ~he carrier film by ~lexing the polyester ~harplyO The laminate~ which was white on one slde and black on the other side9 was still somewhat flexibleO It was dried at lO0~ C. ~or a ~ew minutes to make it brittle9 at which point it was easil~ broken into micropartlcles by a -~
blender as de~cr:lbed in example lo Another piece o~ the laminate was dried ~or about lO minutes at lO0~ C0 The laminate became very brittleO
, ; -.. . . .................... . . . ......... .
, , . ~ . ~ . : . :. .
The lamlnate was then removed by rlexin~ the polyester sharplyO In this case the aluminum from the carrier ~llm vapor coat adhered to the lamlnate so l;hat the m:lcroparticles ~ were black on one side and had an alumiLnum mirror on the ; 5 other sldeO When the micropartlcles were viewed on edge9 the colored layers were seen easily~ but the aluminum was too thin to be seen edgewlse at lOOX magni~icatlon. Nevertheless9 because it could be seen from the side~ it might be con~
sidered as part o~ the codeO
When the microparticles are immersed in water9 they tend to re-dissolve withln a few hoursO They can be made insoluble by immersion in a solution of a metal ; ~;
salt which will replace the sodium in the sodium sillcate with a metal whose silicate is insoluble in waterO For example, immersion of the particles for 24 hours in a 20 percent aqueous solution of aluminum sul~ate (Al2(S04~3018H20 will make the particles insoluble in ~ater o~ pH 80 ~.
~ 10 ~
Claims (8)
1. In a plurality of batches of micro-particles useful for tagging substances to permit retro-spective identification, wherein microparticles of each batch are uniformly and uniquely encoded with an orderly sequential arrangement of at least three visually dis-tinguishable colored layers and each microparticle measures 15 to 1,000 micrometers across the color sequence, the improvement comprising: the external surfaces of the colored layers at the extremities of the code of each micro particle are generally flat and parallel to each other and its other surfaces have irregular, broken shapes, the broadest dimension of most of the particles being greater than the distance between said parallel surfaces.
2. The improvement as defined in claim 1 wherein magnetic material is incorporated into one or more of the colored layers.
3. The improvement as defined in claim 1 wherein trace-element encoded microparticles are incorporated into one or more of the colored layers to provide a secondary means of identification.
4. The improvement as defined in claim 1 wherein one or more of the colored layers contain a fluores-cent or phosphorescent material.
5. The improvement as defined in claim 1 wherein the colored layers are formed from an organic resin which is brittle at room temperature when fully cured.
6. The improvement as defined in claim 5 wherein the colored layers are formed from melamine alkyd or melamine acrylate resin.
7. A process for preparing irregularly-shaped, color coded identifier particles comprising:
combining at least three visually dis-tinguishable colored layers in a pre-determined color sequence to form a laminate having a thickness of 15 to 1,000 micro-meters;
randomly breaking up the laminate into microparticles encoded by an orderly sequential arrangement of colored layers so that the external surfaces of the colored layers at the extremities of the code of each microparticle are generally flat and parallel to each other and its other sur-faces have irregular, broken shapes, the broadest dimension of most of the particles being greater than the distance between said parallel surfaces.
combining at least three visually dis-tinguishable colored layers in a pre-determined color sequence to form a laminate having a thickness of 15 to 1,000 micro-meters;
randomly breaking up the laminate into microparticles encoded by an orderly sequential arrangement of colored layers so that the external surfaces of the colored layers at the extremities of the code of each microparticle are generally flat and parallel to each other and its other sur-faces have irregular, broken shapes, the broadest dimension of most of the particles being greater than the distance between said parallel surfaces.
8. The process according the claim 7 wherein the colored layers of the laminate are sequentially applied to a releasable carrier sheet and said carrier sheet removed prior to breaking up the laminate.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US63042875A | 1975-11-10 | 1975-11-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1056653A true CA1056653A (en) | 1979-06-19 |
Family
ID=24527126
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA263,249A Expired CA1056653A (en) | 1975-11-10 | 1976-10-13 | Color-coded identifier microparticles |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5268278A (en) |
| CA (1) | CA1056653A (en) |
| DE (1) | DE2651528A1 (en) |
| FR (1) | FR2330537A1 (en) |
| GB (1) | GB1568699A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5294476A (en) * | 1988-12-09 | 1994-03-15 | Minnesota Mining And Manufacturing Company | Patterning process and microparticles of substantially the same geometry and shape |
| US6455157B1 (en) * | 1998-11-21 | 2002-09-24 | Simons Druck & Vertrieb Gmbh | Method for protecting and marking products by using microparticles |
| US7720254B2 (en) | 2006-03-13 | 2010-05-18 | Smi Holdings, Inc. | Automatic microparticle mark reader |
Families Citing this family (27)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4390452A (en) * | 1979-08-20 | 1983-06-28 | Minnesota Mining & Manufacturing Company | Microparticles with visual identifying means |
| US4329393A (en) | 1980-05-21 | 1982-05-11 | Minnesota Mining And Manufacturing Company | Coating compositions for retrospective identification of articles |
| US4359399A (en) * | 1980-08-27 | 1982-11-16 | The United States Of America As Represented By The Secretary Of The Air Force | Taggants with explosive induced magnetic susceptibility |
| US4640035A (en) * | 1981-09-03 | 1987-02-03 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Identifying means |
| US5429392A (en) * | 1993-06-18 | 1995-07-04 | Loving; Charles D. | Composite microdot and method |
| GB2318666B (en) * | 1994-04-25 | 1998-07-15 | Univ Hertfordshire | Coded items for labelling objects |
| GB9410196D0 (en) * | 1994-05-21 | 1994-07-13 | Alpha Dot Europ Limited | Identification markers and methods for forming the same |
| GB9521943D0 (en) * | 1995-10-26 | 1996-01-03 | Univ Hertfordshire | Coded particles for process sequence tracking in combinatorial compound library preparation |
| DE19614174A1 (en) * | 1996-04-10 | 1997-11-06 | Simons Druck & Vertrieb Gmbh | Process for the production of multilayer microparticles |
| ATE233300T1 (en) | 1997-12-29 | 2003-03-15 | Sicpa Holding Sa | COATING COMPOSITION, USE OF PARTICLES, METHOD FOR MARKING AND IDENTIFYING A SECURITY DOCUMENT CONTAINING THIS COATING COMPOSITION |
| US6647649B2 (en) | 1998-12-04 | 2003-11-18 | Tracking Technologies, Inc. | Microparticle taggant systems |
| WO2000034937A1 (en) * | 1998-12-04 | 2000-06-15 | Tracking Technologies, Inc. | Multi-colored taggant elements |
| US7015047B2 (en) | 2001-01-26 | 2006-03-21 | Aviva Biosciences Corporation | Microdevices having a preferential axis of magnetization and uses thereof |
| US7811768B2 (en) | 2001-01-26 | 2010-10-12 | Aviva Biosciences Corporation | Microdevice containing photorecognizable coding patterns and methods of using and producing the same |
| US7572642B2 (en) | 2001-04-18 | 2009-08-11 | Ambrigen, Llc | Assay based on particles, which specifically bind with targets in spatially distributed characteristic patterns |
| NL1034314C2 (en) * | 2007-08-31 | 2009-03-03 | Spuitgietbedrijf Salentijn B V | Trade coin, has one or more codes for identifying coin, where coin is encoded with feature consisting of elements with specific layer shaped color indication, and elements are made of plastic material |
| FR2931985B1 (en) * | 2008-05-29 | 2010-08-20 | Patrice Geraudie | METHOD FOR IDENTIFYING A VALUE OBJECT, IN PARTICULAR A WORK OF ART, VALUE OBJECT SO MARKED |
| MX2012006134A (en) | 2009-12-18 | 2012-06-19 | Constr Res & Tech Gmbh | Method for qualitatively and quantitatively identifying bulk goods. |
| EP2688011A1 (en) | 2012-07-19 | 2014-01-22 | 3S Simons Security Systems GmbH | Microparticle, in particular microparticle for tamper-proof marking of products |
| ITTO20121155A1 (en) * | 2012-12-27 | 2014-06-28 | Fond Istituto Italiano Di Tecnologia | MULTILAYER MICROPARTICLE INCLUDING FLUOROPHORS |
| DE102013013108A1 (en) | 2013-08-06 | 2015-02-12 | Jürgen Martens | Lanthanide-containing marking composition for the counterfeit-proof marking of objects, their production and use |
| EP2896508B1 (en) | 2014-01-16 | 2016-12-28 | 3S Simons Security Systems GmbH | Recognition system for security codes |
| DE102014005685A1 (en) * | 2014-04-11 | 2015-10-29 | Bundesrepublik Deutschland, Vertreten Durch Den Bundesminister Für Wirtschaft Und Energie, Dieser Vertreten Durch Den Präsidenten Der Bundesanstalt Für Materialforschung Und -Prüfung (Bam) | Bar code carrier particles, production and use |
| US9972224B2 (en) | 2014-06-27 | 2018-05-15 | Eastman Chemical Company | Fibers with multicomponent fibers used for coding |
| US9863920B2 (en) | 2014-06-27 | 2018-01-09 | Eastman Chemical Company | Fibers with chemical markers and physical features used for coding |
| US9851341B2 (en) | 2014-06-27 | 2017-12-26 | Eastman Chemical Company | Fibers with chemical markers used for coding |
| EP3156945A1 (en) | 2015-10-13 | 2017-04-19 | 3S Simons Security Systems GmbH | Method for producing at least one microparticle, in particular a microparticle for the non-falsifiable marking of products, and microparticle |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR544749A (en) * | 1921-12-21 | 1922-09-27 | New method of coloring in their thickness of plastic sheets or sticks | |
| US3128744A (en) * | 1963-01-02 | 1964-04-14 | Keith B Jefferts | Method for investigating the migratory habits of macro-organisms |
| US3835782A (en) * | 1972-09-22 | 1974-09-17 | Commercial Solvents Corp | Product and method |
-
1976
- 1976-10-13 CA CA263,249A patent/CA1056653A/en not_active Expired
- 1976-11-09 GB GB4662476A patent/GB1568699A/en not_active Expired
- 1976-11-09 FR FR7633689A patent/FR2330537A1/en active Granted
- 1976-11-09 JP JP13461376A patent/JPS5268278A/en active Pending
- 1976-11-09 DE DE19762651528 patent/DE2651528A1/en not_active Withdrawn
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5294476A (en) * | 1988-12-09 | 1994-03-15 | Minnesota Mining And Manufacturing Company | Patterning process and microparticles of substantially the same geometry and shape |
| US6455157B1 (en) * | 1998-11-21 | 2002-09-24 | Simons Druck & Vertrieb Gmbh | Method for protecting and marking products by using microparticles |
| US7720254B2 (en) | 2006-03-13 | 2010-05-18 | Smi Holdings, Inc. | Automatic microparticle mark reader |
| US7831042B2 (en) | 2006-03-13 | 2010-11-09 | Smi Holdings, Inc. | Three-dimensional authentication of microparticle mark |
| US7885428B2 (en) | 2006-03-13 | 2011-02-08 | Smi Holdings, Inc. | Automatic microparticle mark reader |
| US8033450B2 (en) | 2006-03-13 | 2011-10-11 | Smi Holdings, Inc. | Expression codes for microparticle marks based on signature strings |
| US8223964B2 (en) | 2006-03-13 | 2012-07-17 | Smi Holdings, Inc. | Three-dimensional authentication of mircoparticle mark |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2330537A1 (en) | 1977-06-03 |
| GB1568699A (en) | 1980-06-04 |
| DE2651528A1 (en) | 1977-05-12 |
| FR2330537B1 (en) | 1981-07-10 |
| JPS5268278A (en) | 1977-06-06 |
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