I 1111111111111111 11111 1111111111 1111111111 111111111111111 IIIIII IIII IIII IIII
`US007070624B2
`
`c12) United States Patent
`Holmes, III et al.
`
`(IO) Patent No.:
`(45) Date of Patent:
`
`US 7,070,624 B2
`Jul. 4, 2006
`
`(54) PROCESS FOR SEPARATING POLYESTER
`FROM OTHER MATERIALS
`
`(75)
`
`Inventors: John Mitchell Holmes, III,
`Spartanburg, SC (US); Richard Philip
`Zink, Spartanburg, SC (US)
`
`(73) Assignee: United Resource Recovery
`Corporation, Spartanburg, SC (US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 176 days.
`
`(21) Appl. No.: 10/174,760
`
`(22) Filed:
`
`Jun. 19, 2002
`
`(65)
`
`Prior Publication Data
`
`US 2003/0010680 Al
`
`Jan. 16, 2003
`
`Related U.S. Application Data
`
`(60) Provisional application No. 60/299,273, filed on Jun.
`19, 2001.
`
`(51)
`
`Int. Cl.
`(2006.01)
`D06M 11100
`(2006.01)
`C0SF 12102
`(2006.01)
`C0SL 27112
`(2006.01)
`C0SJ 11104
`(52) U.S. Cl. ......................... 8/130; 8/115.51; 209/172;
`521/48; 525/199; 526/67; 528/489
`(58) Field of Classification Search .................. 521/48;
`8/115.51, 130; 209/172; 528/489; 525/199;
`526/67
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
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`
`3/1960 Schutt
`7/1962 Wemple
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`6/1966 Whitfield, Jr. et al.
`9/1968 Farrow
`3/1970 Dietz et al.
`12/1970 England
`5/1971 Amedjian et al.
`7/1971 Katzschmann
`3/1972 Wainer
`3/1972 Hittel et al.
`3/1975 Woo et al.
`3/1975 Wu et al.
`5/1975 Ostrowski
`12/1975 Thornton et al.
`4/1976 Brown, Jr. et al.
`4/1976 Fassell et al.
`5/1976 Fassell et al.
`7/1977 Wolf
`3/1978 Malik et al.
`8/1979 Delattre et al.
`2/1980 Luke
`5/1980 Tanouchi et al.
`7/1980 Ide!
`
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`4/1982 Seto et al.
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`10/1982 Pusztaszeri
`4,355,175 A
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`1/1983 Scott
`4,392,889 A
`7/1983 Grout
`4,578,502 A
`3/1986 Cudmore
`4,578,510 A
`3/1986 Doerr
`4,602,046 A
`7/1986 Buser et al.
`4,605,762 A
`8/1986 Mandoki
`9/1986 Buser et al.
`4,612,057 A
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`10/1986 Doerr
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`12/1986 Packer et al.
`4,629,780 A
`12/1986 Schoenhard
`4,898,912 A * 2/1990 Siol et al .................... 525/199
`5,064,466 A
`11/1991 Hilton
`5,095,145 A
`3/1992 Rosen
`5,120,768 A
`6/1992 Sisson
`5,234,110 A
`8/1993 Kobler
`5,248,041 A
`9/1993 Deiringer
`5,254,666 A
`10/1993 Benzaria
`5,286,463 A
`2/1994 Schwartz, Jr.
`5,366,998 A
`11/1994 Schwartz, Jr.
`5,395,858 A
`3/1995 Schwartz, Jr.
`5,580,905 A
`12/1996 Schwartz, Jr.
`
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`
`10032899 Al
`
`1/2002
`
`(Continued)
`
`Primary Examiner-Douglas McGinty
`Assistant Examiner-Preeti Kumar
`(74) Attorney, Agent, or Firm-Dority & Manning, P.A.
`
`(57)
`
`ABSTRACT
`
`The present invention is directed to a process for separating
`polyester, and particularly polyethylene terephthalate, from
`various contaminants and impurities. In general, the process
`includes the steps of mixing materials containing polyester
`with an alkaline composition in a mixer. The mixer imparts
`sufficient energy to the slurry to provide substantially com(cid:173)
`plete, even coating of the polyester containing materials
`with the alkaline composition and cause saponification of
`the outer surface of the polyester with the alkaline compo(cid:173)
`sition. After reaction in the mixer, the mixture is heated
`causing some of the impurities to be chemically modified
`into a more separable form. After heating, the mixture can be
`washed with water and the polyester can be easily separated
`from the remaining impurities. Through the process of the
`present invention, polyester can be separated and recovered
`from waste materials such as those containing polyvinyl
`chloride and aluminum. The process is also effective at
`removing coatings adhered to the polyester and at removing
`entrained organic and inorganic compounds contained
`within the polyester.
`
`41 Claims, No Drawings
`
`Petitioner Samsung and Google
`Ex-1016, 0001
`
`

`

`US 7,070,624 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`FOREIGN PATENT DOCUMENTS
`
`5,958,987 A
`6,147,129 A
`6,197,838 Bl
`6,369,173 Bl*
`
`9/ 1999 Schwartz, Jr. et al.
`11/2000 Schwartz, Jr.
`3/2001 Schwartz, Jr. et al.
`4/2002 Kim et al.
`.................... 526/67
`
`EP
`GB
`
`0550979 A2
`610135
`
`7 /1993
`10/1948
`
`* cited by examiner
`
`Petitioner Samsung and Google
`Ex-1016, 0002
`
`

`

`US 7,070,624 B2
`
`1
`PROCESS FOR SEPARATING POLYESTER
`FROM OTHER MATERIALS
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This application claims priority to an earlier filed U.S.
`provisional patent application Ser. No. 60/299,273 filed Jun.
`19, 2001 entitled, "Process for Separating Polyester from
`other Materials."
`
`BACKGROUND OF THE INVENTION
`
`2
`when placed in an aqueous medium. In order for these
`processes to be efficient, however, the PVC flakes must have
`a high surface area to volume ratio. Consequently, the above
`processes are deficient in separating PVC chips from PET
`5 when the PVC chips have a large interior volume.
`Besides failing to separate polyesters from heavier-than(cid:173)
`water impurities, floatation separation techniques also fail to
`remove coatings that are commonly adhered to polyester.
`For example, polyester containers are commonly coated
`10 with vapor barrier coatings, saran coatings, and/or inks.
`Mechanical recovery processes as used herein are wash(cid:173)
`ing processes used to strip specific binder and adhesive
`layers off polyester films without substantial reaction occur(cid:173)
`ring between the polyester and the wash solution. For
`15 example, U.S. Pat. Nos. 5,286,463 and 5,366,998 both to
`Schwartz, Jr., both of which are incorporated herein by
`reference thereto, disclose a composition and process for
`removing adhesives, particularly polyvinylidene halide and
`polyvinyl halide based resins, from polyester films, such as
`20 photographic films. In one embodiment, the polyester films
`are mixed with a reducing sugar and a base to remove the
`adhesive polymeric resin from the film. An acid is then
`added to precipitate the resin, which can then be separated
`from the polyester film.
`U.S. Pat. No. 4,602,046 to Buser et al. discloses a method
`for the recovery of polyester from scrap material such as
`photographic film having a polyester base and at least one
`layer of macromolecular organic polymer. Specifically,
`scrap material is cut or chopped into small individual pieces
`30 or flakes and treated in a caustic alkaline solution at a solids
`level of at least 25% by volume and under conditions of high
`shear. The organic polymer coating material is removed
`from the polyester flakes. The polyester flakes are then
`separated from the polymer coating material by filtration or
`35 centrifugation, rinsed in water, and dried. The recovered
`polyester flakes can be used as a feed stock for making films,
`bottles or other polyester articles. A method and apparatus
`for recovering silver and plastic from used film is also
`disclosed in U.S. Pat. No. 4,392,889 to Grout. In this
`40 method, the used film is first passed through a bath prefer(cid:173)
`ably comprising a hot caustic solution for precipitating silver
`layered on the film. The film then passes through a second
`bath of hot caustic until an adhesive sheet disposed on the
`film has been dissolved. Typically, the adhesive sheet is
`45 made of polyvinylidene chloride, which adheres the silver to
`the film. After a second caustic bath, the film is dried and
`available for use.
`Other processes for recovering polyester from photo(cid:173)
`graphic films are disclosed in U.S. Pat. No. 3,928,253 to
`50 Thornton et al., U.S. Pat. No. 3,652,466 to Hittel et al., U.S.
`Pat. No. 3,647,422 to Wainer, and U.S. Pat. No. 3,873,314
`to Woo et al.
`As shown above, mechanical recovery processes have
`generally been limited to use with photographic films. In
`recycling the photographic films, silver is also recovered
`making the processes economically viable. Mechanical
`recovery processes, although very successful at removing
`the emulsion-type coatings found on photographic films,
`have generally not been successful in removing other types
`of coatings from polyesters. For instance, most of these
`processes are not capable of efficiently removing some of the
`vapor barrier coatings and inks that are applied to polyesters.
`Other contaminants that are generally not removable from
`polyesters using floatation separation
`techniques and
`mechanical recovery processes as described above are
`entrained organic and inorganic compounds. These contami-
`nants include, for instance, gasoline, kerosene, motor oil,
`
`25
`
`Polyesters are polymeric materials made from the esteri(cid:173)
`fication of polybasic organic acids with polyhydric acids.
`Perhaps the most commonly made and used polyester is
`polyethylene terephthalate (PET), which can be manufac(cid:173)
`tured by reacting terephthalic acid with ethylene glycol.
`Polyesters are currently being used in increasing amounts
`in various applications. For instance, polyesters are com(cid:173)
`monly used to make all types of containers such as beverage
`and food containers, photographic films, X-ray films, mag(cid:173)
`netic recording tapes, electrical insulation, surgical aids such
`as synthetic arteries, fabrics and other textile products, and
`other numerous items.
`Because polyesters can be remelted and reformed, many
`efforts are underway to recycle as much polyester as possible
`after use. Before polyesters can be recycled, however, it is
`necessary to separate the post-consumer polyesters from
`other products and materials that may be found mixed with
`or coupled with the polyester. Unfortunately, many problems
`have been encountered in attempting to separate polyester
`from other waste materials. In particular, many prior art
`processes are not capable of efficiently or economically
`recovering polyester when a significant amount of impurities
`and contaminants are present. Most prior art processes for
`separating polyesters from other materials have been limited
`to floatation separation techniques and mechanical recovery
`processes.
`In floatation separation techniques, polyesters are sepa(cid:173)
`rated from other materials based on density differences. For
`instance, materials containing polyester can be combined
`with water, in which polyester is known to sink. The less
`dense materials, which float in water, can thus be easily
`separated from the submerged polyester. This procedure is
`relatively simple and very effective in separating polyesters
`from specific low density impurities. Floatation separation
`techniques, however, cannot be used if the polyester is found
`in combination with materials that sink in water or that have
`densities comparable to that of polyester.
`For instance, post consumer polyester is typically mixed
`with polyvinyl chloride (PVC) and aluminum, which are not
`water buoyant. In fact, PVC has a density that is very similar
`to the density of PET and is often misidentified as PET. Both
`aluminum and PVC must be separated from polyester before 55
`it can be reused. In particular, if PET and PVC are remelted
`together, hydrochloric acid gases are produced which
`destroy the properties of the resulting plastic material.
`In the past, in order to separate PET from PVC using a
`floatation separation technique in a specific gravity bath, 60
`others have attempted to modify the surface of the PVC so
`that the PVC will float in an aerated aqueous medium. For
`instance, in U.S. Pat. No. 5,234,110 to Kobler and U.S. Pat.
`No. 5,120,768 to Sisson various processes for separating
`PET from PVC flakes are disclosed. In these processes, the 65
`surface of the PVC flakes is treated in a manner so that the
`surface of the PVC is more likely to adhere to air bubbles
`
`Petitioner Samsung and Google
`Ex-1016, 0003
`
`

`

`US 7,070,624 B2
`
`3
`toluene, pesticides and other compounds that are absorbed
`by polyesters when placed in contact therewith. If the
`entrained organic and inorganic compounds are not substan(cid:173)
`tially removed from the polyester materials during recy(cid:173)
`cling, the recycled polyesters cannot be used as food con(cid:173)
`tainers or as beverage containers.
`Because of the above noted deficiencies in prior art
`processes, large amounts of recyclable polyesters are being
`scrapped and loaded into landfills or are being incinerated.
`Unfortunately, not only is the polyester not being reused, but
`the polyester materials are creating a waste management and
`disposal problem.
`Recently, the focus of recovering polyester from the waste
`stream has changed from mechanical washing processes to
`chemically converting the polyester into usable chemical
`components. For instance, in U.S. Pat. No. 5,958,987, 6,147,
`129, and 6,197,838, all to Schwartz, Jr., which are incorpo(cid:173)
`rated herein by reference thereto, processes for recycling
`polyesters in which a portion of the polyesters are reduced
`to their original chemical reactants are disclosed. The pro(cid:173)
`cesses include the steps of combining the polyester materials
`with an alkaline composition to form a mixture. The mixture
`is heated to a temperature sufficient to convert the surface of
`the polyester to an alkaline salt of a polybasic organic acid
`and a polyol.
`The above described patents represent great advance(cid:173)
`ments in the art. The process of the present invention is
`directed to further improvements in processes for recycling
`polyesters.
`
`SUMMARY OF THE INVENTION
`
`4
`the polyester as possible and yet still promote separation of
`the polyester from any contaminants or impurities. For
`example, the alkaline composition can be combined with the
`polyester materials in an amount of less than about 10% by
`5 weight of the polyester materials. Specifically, the alkaline
`composition can be combined with the polyester materials in
`a stoichiometric amount sufficient to react with less than
`about 20% of the polyester. More specifically, the alkaline
`composition can be combined with the polyester materials in
`10 a stoichiometric amount sufficient to react with less than
`about 10% of the polyester.
`The reaction process can substantially exhaust the metal
`hydroxide in the mixer. For example, the metal hydroxide
`remaining in the slurry after the mixing and reaction process
`15 can generally be less than about 1 % of the weight of the
`slurry. Specifically, the metal hydroxide remaining in the
`slurry after the mixing and reaction process can generally be
`less than about 0.5% of the weight of the slurry. More
`specifically, the metal hydroxide remaining in the slurry
`20 after the mixing and reaction process can generally be less
`than about 0.1 % of the weight of the slurry.
`If desired, the slurry can be heated after the reaction in the
`mixer is substantially complete. For example, the slurry can
`be heated to a first temperature, such as, for example, a
`25 temperature of between about 120° C. and about 170° C., to
`dry the slurry and produce a dry product, and then heated to
`a second temperature, such as, for example a temperature of
`between about 200° C. and about 240° C., which can further
`degrade the contaminants and make them easier to separate
`30 from the polyester substrate.
`In one embodiment, the polyester containing materials
`can include contaminants which are coupled to the polyester
`substrate, such as contaminants which are entrained in the
`polyester or contaminants which are adhered to the surface
`35 of the polyester. In this embodiment, the alkaline composi(cid:173)
`tion can react with the materials during mixing and cause
`saponification of a portion of the polyester which can release
`the contaminants from the surface of the polyester substrate.
`Alternatively, the polyester containing materials can
`40 include impurities or contaminants which are mixed with the
`polyester, though not necessarily coupled to the polyester,
`such as polyvinyl chloride or aluminum materials, for
`example. In this embodiment, the alkaline composition can
`react with the contaminant and cause them to be altered into
`a form which is more easily separable from the polyester.
`For example, polyvinyl chloride can be dechlorinated by the
`alkaline composition in which form it can be easily sepa(cid:173)
`rated from the polyester substrate.
`
`In general, the process of the present invention is directed
`to a process for separating a polyester substrate from various
`contaminants and impurities. For example, the process of the
`present invention can be used to release various contami(cid:173)
`nants from a polyester substrate to which the contaminants
`have been coupled, i.e. either adhered or entrained contami(cid:173)
`nants. Additionally, the process of the present invention can
`facilitate the separation of polyester from other contami(cid:173)
`nants which can be mixed with polyester in the waste
`stream; aluminum and polyvinyl chloride, for example.
`The process of the present invention generally includes
`mixing materials containing polyester with an alkaline com(cid:173)
`position to form a slurry. The slurry can then be mixed in a 45
`high energy mixer which can not only substantially and
`evenly coat the materials with the alkaline composition, but
`can also impart sufficient energy so as to promote reaction
`between the materials and the alkaline composition which
`can enable separation of the polyester from various con- 50
`taminants and impurities. For example, the slurry can be
`mixed in a high energy plow mixer. In one embodiment, the
`mixer can operate at a Froude number greater than about 4.2
`to promote the reaction. Specifically, the mixer can operate
`at a Froude number greater than about 6.6. In one embodi- 55
`ment, the mixer can operate at a Froude number greater than
`about 9.5.
`In general, the alkaline composition can be a metal
`hydroxide solution. For example, the metal hydroxide can be
`sodium hydroxide, calcium hydroxide, potassium hydrox- 60
`ide, lithium hydroxide, magnesium hydroxide, or mixtures
`thereof. In one embodiment, the alkaline composition can be
`formed of only sodium hydroxide and water. For example,
`the alkaline composition can be sodium hydroxide and water
`in a 1: 1 ratio.
`The alkaline composition can be combined with the
`polyester materials in an amount so as to saponify as little of
`
`65
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`The present invention is generally directed to a process
`for recovering and separating polyesters from various con(cid:173)
`taminants and impurities. For instance, through the process
`of the present invention, various contaminants can be
`released from a polyester substrate such as various coatings
`including vapor barrier coatings, inks, and saran coatings as
`well as other contaminants which are entrained within the
`outer surface of the polyester substrate, such as various
`volatile organic and inorganic contaminants. During the
`process, the polyester can be partially saponified but largely
`remain in polymer form and the contaminants can be physi(cid:173)
`cally released from the polyester substrate.
`The process is also directed to the separation and recovery
`of polyester when mixed with other types of impurities such
`as polyvinyl chloride and aluminum, for example. During
`
`Petitioner Samsung and Google
`Ex-1016, 0004
`
`

`

`US 7,070,624 B2
`
`5
`the process, the impurities can be converted into a form
`which is more easily separable from the polyester substrate.
`As used herein, a polyester is defined as an esterification
`or reaction product between a polybasic organic acid and a
`polyol. It is believed that any known polyester or copoly-
`ester may be used in the process of the present invention.
`The process of the present invention is particularly directed
`to a class of polyesters referred to herein as polyol poly(cid:173)
`terephthalates, in which terephthalic acid serves as the
`polybasic organic acid.
`As used herein, a polybasic organic acid refers to any
`organic acid having
`two or more carboxyl groups
`(--COOR). Most polyesters are derived from dibasic acids
`or, in other words, from dicarboxylic acids. Polybasic acids
`can have a linear or a cyclic conformation. Examples of 15
`linear polybasic acids that can be used to make polyesters
`include the aliphatic dicarboxylic acids. In particular the
`aliphatic dicarboxylic acids having up to ten carbon atoms in
`their chains can be used. These acids include adipic acid,
`glutaric acid, succinic acid, malonic acid, oxalic acid, 20
`pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic
`acid, and fumaric acid.
`Cyclic polybasic organic acids, on the other hand, include
`the carbocyclic dicarboxylic acids. These acids are known as
`phthalic acid, isophthalic acid, and terephthalic acid. In 25
`particular, terephthalic acid is used to make polyethylene
`terephthalate, which is perhaps the most commercially avail(cid:173)
`able polyester.
`As described above, a polybasic organic acid is combined
`with a polyol to produce a polyester. Polyols are compounds 30
`that contain at least two hydroxyl groups. Many polyesters
`are synthesized using a polyol that contains two hydroxyl
`groups, which are referred to as dials. Dials are normally
`prepared from an alkene by the net addition of two hydroxy
`groups to the double carbon bond in a method known as 35
`hydroxylation. Polyols are commonly referred to as glycols
`and polyhydric alcohols. Examples of polyols used to make
`polyesters include ethylene glycol, propylene glycol, buty(cid:173)
`lene glycol, and cyclohexane dimethanol.
`For exemplary purposes, the following table contains a 40
`nonexhaustive list of commercially available polyesters that
`may be recovered and recycled according to the present
`invention. For each polyester, the corresponding polybasic
`organic acid and polyol are provided.
`
`5
`
`6
`mixer. The mixer chosen is one which can not only provide
`substantially complete and even coating of the polyester
`materials by the alkaline solution, but also can impart
`sufficient energy to cause a portion of the polyester to
`saponify, or, in other words, to hydrolyze. During saponifi(cid:173)
`cation, various coatings that may be adhered to the polyester
`and/or other contaminants which may be entrained within
`the surface of the polyester can be released from the poly(cid:173)
`ester. The energy provided from the mixer can also promote
`10 reaction between the alkaline solution and other impurities
`which can be mixed in with the polyester in the slurry, such
`as polyvinyl chloride or aluminum, for example, such that
`the impurities can be converted to another form, one which
`is more easily separable from the polyester substrate. After
`the reaction within the mixer, the slurry can then be heated,
`usually in a two-step heating process.
`The process of the present invention can run continuously
`or can be set up as a batch system. Practically any material
`containing a polyester can be processed by the present
`invention including but not limited to, for example, beverage
`and food containers, photographic and X-ray films, record-
`ing tapes, insulation materials, textile fibers and other prod(cid:173)
`ucts. Preferably, the polyester materials are recovered from
`the solid waste stream, thus alleviating many environmental
`concerns and disposal problems. The present invention is
`particularly directed to recycling food containers and bev-
`erage containers made from PET. Through the process of the
`present invention, polyesters can be separated, recovered
`and reused from post consumer waste, even when the
`polyesters are found mixed with polyvinyl chloride or
`aluminum, adhered to various coatings, or entrained with
`various organic and inorganic compounds. Such materials
`are currently being disposed of in landfills or are being
`incinerated after use due to a lack of an economical process
`that will recover the polyester.
`Prior to being contacted with the alkaline composition,
`the materials containing the polyester can be, if desired,
`chopped or ground into a particular size. Sizing of the
`materials is done solely for the purpose of facilitating
`handling. Generally speaking, the larger the size of the
`materials and the less surface area to volume ratio, the less
`saponification of the polyester will occur later in the process.
`Consequently, smaller dimensions should be avoided and
`the size of the materials should be left as large as practicable.
`45 However, it should be understood that all different sizes and
`shapes of material may be used within the process of the
`present invention and no one size or shape is required.
`Also prior to being combined with the alkaline composi(cid:173)
`tion, the materials containing the polyester can be immersed
`50 in water or some other fluid in order to separate the less
`dense or lighter materials from the heavier materials con(cid:173)
`taining the polyester. More particularly, it is known that
`polyester sinks in water while paper products and other
`polymers, such as polyolefins, are water buoyant. Thus, the
`55 lighter materials can be easily separated from the heavier
`materials when contacted with a fluid. Subjecting the mate(cid:173)
`rials to a sink/float separation step prior to contacting the
`materials with the alkaline composition not only can reduce
`the quantity of materials being processed but also can clean
`60 the surface of the materials prior to further processing.
`After being sized and subjected to a sink/float separation,
`if desired, the polyester containing materials can be com(cid:173)
`bined and mixed with an alkaline composition to form a
`slurry, or mixture. Preferably, an alkaline solution can be
`65 combined with the materials so as to coat the material
`surface. In some applications, the material surface can resist
`uniform coating due to surface tension interaction. In this
`
`POLYESTER
`
`Polyethylene
`Terephthalate
`Polybutylene
`Terephthalate
`PETG Copolyester
`
`POLYBASIC
`ORGANIC ACID
`
`DIOL
`
`Terephthalic Acid
`
`Ethylene Glycol
`
`Terephthalic Acid
`
`Butylene Glycol
`
`Terephthalic Acid
`
`Cyclohexane-
`dimethanol and
`Ethylene Glycol
`Cyclohexane-
`dimethanol
`and
`Butylene Glycol
`Cyclohexane-
`dimethanol
`
`Ethylene Glycol
`
`PBTG Copolyester
`
`Terephthalic Acid
`
`Polycyclohexane-
`dimethanol
`Terephthalate
`PEN Polyester
`
`Terephthalic Acid
`
`Napthalene Dicarboxylic
`Acid
`
`In general, the process of the present invention includes
`first combining materials containing polyester with a
`selected amount of an alkaline solution to form a slurry in a
`
`Petitioner Samsung and Google
`Ex-1016, 0005
`
`

`

`US 7,070,624 B2
`
`8
`weight of the material containing the polyester, and particu(cid:173)
`larly in an amount less than about 10% by weight of the
`material containing the polyester.
`The mixer can be operated at a rate which can impart
`5 sufficient energy to the mixture so as to substantially evenly
`coat the polyester material with the alkaline mixture and
`promote saponification of the outside surface of the poly(cid:173)
`ester material such that most of the alkaline reactant is
`exhausted in the mixer. In general, mixers can normally be
`operated at a preset rotational speed, specific to the particu(cid:173)
`lar device and adapted to the particular process. In order to
`maintain equivalent energy input when using different mix(cid:173)
`ers, the dimensionless value Fr (Froude number) is intro(cid:173)
`duced, instead of the rotational speed. Fr is a dimensionless
`15 number which describes the ratio of inertial forces to gravi(cid:173)
`tational forces. The Froude number can be described by the
`following formula:
`
`25
`
`7
`situation, the alkaline solution has a tendency to "bead up"
`on the material surface. The process of the present invention,
`however, as described below, can overcome this problem.
`In accordance with the present invention, it has been
`discovered that an improved mixing process can be
`employed which can not only coat the polyester materials
`with the alkaline solution more completely and evenly, but
`in addition can impart sufficient energy to the mixture to
`cause saponification of the outside surface of the polyester
`to occur within the mixer. For example, mixers such as those 10
`described in U.S. Pat. No. 4,320,979 to Lucke and U.S. Pat.
`No. 4,189,242 to Luke, which are herein incorporated in
`their entirety by reference thereto, may be employed for
`coating of the polyester materials and saponification of at
`least a portion of the polyester with an alkaline solution.
`The alkaline compound selected for mixing with the
`materials is preferably sodium hydroxide, known commonly
`as caustic soda. Other metal hydroxides and alkalines how(cid:173)
`ever, can be used. Such compounds include calcium hydrox(cid:173)
`ide, magnesium hydroxide, potassium hydroxide, lithium 20
`hydroxide or mixtures thereof. The alkaline compound can
`be added to the polyester materials in solution, if desired.
`For instance, in one embodiment, a metal hydroxide, such as
`sodium hydroxide, can be mixed with water in about a 1: 1
`ratio to form the alkaline composition.
`The amount of the alkaline composition added to the
`materials containing the polyester will depend upon the type
`and amount of impurities and contaminants present within
`the materials. Generally, the alkaline composition should be
`added only in an amount sufficient to separate the impurities 30
`from the polyester, so as to minimize the saponification of
`the polyester. In most applications, the alkaline composition
`is added to the materials in a stoichiometric amount suffi-
`cient to react with up to about 50% of the polyester. For
`example, the alkaline composition can be added in an 35
`amount sufficient to react with less than about 20% of the
`polyester. Specifically, the alkaline composition can be
`added in an amount sufficient to react with about less than
`about 15% of the polyester. More specifically, the alkaline
`composition can be added in an amount sufficient to react 40
`with less than about 10% of the polyester.
`One of the benefits of the present invention is the ability
`of the mixer to coat the polyester material without the need
`of a wetting agent. In the past, a surfactant or wetting agent
`was often employed in order to facilitate the mixing of the 45
`alkaline composition with the polyester materials. Due to the
`improved mixing of the present invention, the use of a
`wetting agent is no longer necessary.
`In one embodiment of the present invention a reactor in
`the form of a mixer can be utilized. In one particular 50
`embodiment, a plow mixer can be used. For example, a plow
`mixer such as those available from the Liidige Company, the
`Littleford Day Company, or other known companies can be
`used. In one particular embodiment, a mixer such as the
`Littleford Day KM-4200 mixer can be utilized. This par- 55
`ticular mixer is available from the Littleford Day Company
`of Florence, Ky. Besides a plow mixer, however, it should be
`understood that various other high energy mixers can be
`used. Similarly, it should be understood that the process can
`be run as either a continuous or a batch process. An amount 60
`of ground or chopped polyester material can be added to the
`mixer after any desired pretreatment processes have been
`performed, such as, for example, the floatation separation
`processes as previously discussed. An alkaline solution can
`then be added to the mixer with the polyester material. For 65
`example, a alkaline solution of 50% NaOH and 50% water
`can be added to the mixer in an amount up to about 20% by
`
`Fr~V2/(gL)
`
`wherein Fr is the Froude number, V is the velocity, g is the
`gravitational acceleration, and L is a characteristic length.
`In one embodiment of the present invention, the mixer can
`be operated at a Froude number greater than about 4.2,
`particularly greater than 6.6, and more particularly greater
`that about 9.5. Specifically, at the above rates, the mixer of
`the present invention not only mixes the slurry but also
`imparts sufficient energy to the slurry to cause the alkaline
`composition to react with the polyester. In fact, mixing can
`be continued until substantially all of t