CA1125975A - Antistatic coated polyester film and process for forming same - Google Patents
Antistatic coated polyester film and process for forming sameInfo
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- CA1125975A CA1125975A CA343,024A CA343024A CA1125975A CA 1125975 A CA1125975 A CA 1125975A CA 343024 A CA343024 A CA 343024A CA 1125975 A CA1125975 A CA 1125975A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/04—Coating
- C08J7/0427—Coating with only one layer of a composition containing a polymer binder
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/04—Coating
- C08J7/043—Improving the adhesiveness of the coatings per se, e.g. forming primers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/04—Coating
- C08J7/044—Forming conductive coatings; Forming coatings having anti-static properties
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2433/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Laminated Bodies (AREA)
- Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A polyester film coated with an antistatic coating is provided. The film includes a polyester film support coated on one side with a latex coating. The coating includes stearamidopropyldimethyl-.beta.-hydroxy-ethylammonium nitrate present in a concentration in the range of between about 2.75 percent and 3.25 percent by weight, based on the total weight of the latex coating. The coating further includes a crosslinkable methylmethacrylate-ethylacrylate-methacrylamide terpolymer having a glass transition temperature in the range of between about 40° C and 50° C. The terpolymer is present in a concentration in the range of between about 0.75 percent and 1.25 percent by weight, based on the total weight of the latex coating. The weight ratio of the nitrate to the terpolymer ranges between about 2.75:1 to below 3:1.
A process for forming the above film is also disclosed.
In this process a latex coating of the composition described above is coated onto a uniaxially drawn polyester film support. The uniaxially drawn film is then heated to drive off the water and thereafter the uniaxially coated film is stretched in a direction normal to that of the uniaxial drawn film.
A polyester film coated with an antistatic coating is provided. The film includes a polyester film support coated on one side with a latex coating. The coating includes stearamidopropyldimethyl-.beta.-hydroxy-ethylammonium nitrate present in a concentration in the range of between about 2.75 percent and 3.25 percent by weight, based on the total weight of the latex coating. The coating further includes a crosslinkable methylmethacrylate-ethylacrylate-methacrylamide terpolymer having a glass transition temperature in the range of between about 40° C and 50° C. The terpolymer is present in a concentration in the range of between about 0.75 percent and 1.25 percent by weight, based on the total weight of the latex coating. The weight ratio of the nitrate to the terpolymer ranges between about 2.75:1 to below 3:1.
A process for forming the above film is also disclosed.
In this process a latex coating of the composition described above is coated onto a uniaxially drawn polyester film support. The uniaxially drawn film is then heated to drive off the water and thereafter the uniaxially coated film is stretched in a direction normal to that of the uniaxial drawn film.
Description
5~
" . , . . , . : .
BACKGROUND OF THE DI SCLOSURE
.
Field of the Invention ~ his invention is directed to an improved polyester film having excellent antistatic properties and the process for producing said film. More specifically, the instant invention is directed ~o a polyester film hav~ng improved antistatic properties in combination with improved slip properties and the process for producing the film. Still more specifically, the instant invention is directed to a 10 polyethylene terephthalate film coated with a latex coating hich imparts excellent antistatic and slip properties and the process for producing the film.
. . . . .
- Summary of the Prior Art -The growth of microfilm and magnetic tape markets has significantly increased the utilization of polyester film as supports for these products. However, polyester film becomes electrostatically charged, especially at low relative humidity. This electrostatic charge attracts not only dust and pther contaminants, but, a~aitionally, attracts other polyester film supports. For instance, electrostatic forces . interfere in the collating, sorting and developing of micro-fiche cards by causing the cards to stick to~ether.
To overcome this serious problem, antis~cltic polyester ilms have been developed. ~ntistatic poly~ter films are ~5 usually formed by the application of an ant~tatic coating onto the surface of the polyester film. Ma~ of these coatings have successfully reduced the electrostatic properties of the polyester film to satisfactorily low levels. HoweYer, many of these coatin~s cause bloc~ing. That is, th~ pol~ester film .
~. -2- .
. .-.
coated wi~h an antistatic layer has a coefficient of friction hi~h enough so that one layer of the film does not slip over another or over rollers and other equipment over which - the film moves duriny operation.
S Another problem arising from the coating o~ an antistatic layer onto the surface of a polyester film is the decreased clarity resulting therefrom. This property, usually reported . as haze, is very important in microfilm applications~ Microfilm must be readable. Light is projected through the film so that the viewer may read the information printed on the film. Poor clarity results in fuzziness and difficulty in reading because of loss of light intensity.
The above discussion indicates the importance of polyester ~ilm having good antistatic propexties, as well as good slip, 1~ or handleabili~y, and clarity~ Thus it is critical that the antistatîc coating provide all three of these properties.
Alt~ough the prior art includes disclosures directed to anti-static coating on polyester films none of them produce films - properties h~ving the combination of good antistatic, slip and clarity/.
V.S. Patent 4,089,997 issued to Van Paesschen et ai includes a disclosure of stearamidopropyldimethyl-~-hydroxy-ethylammonium nitrate. ~owever, the disclosure in the '997 patent includes additional constituents, diferent from those in the instant invention' which do not prod~ce the excellent combination of antistatic, slip and clarity properties.
Not only are the constituents present ~ the antistatic coating critical to the fil~n's antistatic, s~p and clarity properties, but moreovex, the concentrations of these material are similarly o~ ~r~at importance. For inst~nce, ~.S. Patent 3,264,136 issucd to Hcd~e, discloses a coatm~ which includes . .,, O
.. .. . .... ..
, .._ ... .. .
0.2 percent bv volume of stearamidopropyldimethyl.B-hydro~.y-ethylammonium nitrate in combinatio~ with the radditional con-stituents, polymethylmethacrylate. This combination sf constituents did not produce the combinatlon ~f antistatic, 5 slip and clarity properties necessary for utilization in polyester film supported microfilm and magnetic tapes.
An additional requirement in antistatic film technology is not directed to the properties of the film. It is not enough that a latex coating provide the important properties discussed above. The latex coating must be stable. That is, the latex coating cannot precipitate out on standing, to form a two-phase system, for at least one week. This property, satisfactory pot life, is necessary for commercial operation of a coating process. One can ill afford to devise an .antistatic coating providing excellent antistatic, slip. and : properties clarity/which does not stay emulsified long enough to coat a - suitable length of film.
, SUM~RY OF THE INVENTION
~0 The instant invention is directed to a ~olyester film support which not only has outstanding antistatic properties but also very good handleability, that is, good slip properties, as well as excellent clarity. These properties are provided by a latex coating which additionally has excel-lent pot life.
In accordance with the instant inventicn, a polyester film is provicled. The film, which is biaxially oriented, is coated Oll one side with a latex coating. rrhe latex coating includes stearamidopropyldimethyl-~-hydroxyethylammonium nitrate pres~nt in a concentration in the ram~e of between . .
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~125~75 ` . .- , , . . .......................... : .. ~
about 2.75 and 3.25 percent by weight, based on the total weight of the latex coating. Additionally, the coating includes a crosslinked methylmethacrylate-ethy~acrylate-~ methacrylamide terpolymer, having a glass transition temper-ature in the range of between about 40 C and 5~ C, presentin a concentration in the range of between about 0.75 percent and 1.25 percent by weight, based on t~e total weight of the - latex coating. The weight ratio of the two constituents in the Iatex coating, that is, the ratio of the nitrate to the terpolymer, is in the range of between about 2.75.1 and 3.25:1.
In accordance with the process for forming this film, a uniaxially drawn polyester film is coated with a latex coating, de~ined above. The uniaxially drawn polyester film is heated by exposure to ele~ated temperatures whereby ~ lS ~he water in the latex coating is driven off. The dried - latex coated uniaxially drawn film is then stretched, in a direction normal to that of the uniaxially ~rawn film, to form the antistatic, biaxially oriented polyester ~ilm. ~-- . , ' . , 20 DETAILED DESCRIPTIO~
Polyester film, upon which the antistatic layer is disposed, may be formed from any thermoplastic film forming poly~ster producea by condensing a dicarboxylic acid or a lower alkyl diester thereof wi~h a glycol. Among the dicarboxylic acids or their lower alkyl diesters within the contemplation o~ this inventian include terephthalic;
isophthalic; phthalic; 2~5,2,6; or 2,7-napth~lene dicarboxylic;
succinic; sebacic, adipic; azelaic, bibenzoi~; and hexahydro-terephthalic acids; and bis~p carbo~y phenox~ ethane. One or more o~ these dicarboxylic acids or their lo~er al~yl diesters is , . O
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: : ' ;~
~5~75 : .
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reacted with one or more glycols which include ethylenç
, glycol; 1,3-pro~anediol; 1,4-butanediol; neopentyl glycol or 1,4-cyclohexanedimethanol. In that one or ~ore diesters - may be reacted with one or more glycols, the polyestex ilm ' of this invention is not limited to homopolyesters but also includes copolyesters. .
, Of the film forming polyesters within the contemplation of this invention the most preferred is polyethylene tereph-thal~te. Polyethylene terephthalate film is formed from a polymer produced by polymerization of bis~2-hydroxy ethyl) ~'' tèrephthalate. Bis (2-hydroxy ethyl) terephthalate is itself formed as an intermediate by one of two different methoas.
One method for producing bis(2-hydroxy ethyl) -terephthalate --is ~y direct esterification of terephthalic acid,and ,ethylene : 15 ~lycoi as described in U.S. Patent 3L050,533. In this method ~:, . .
the bi-product of the reaction is water which is distilled - from,'the reaction product. A second method for producing . bis (2-hydroxy ethyl) texephthalate is by transesterification - of a dialkyl ester of terephthalic acid, preferably dimethyl terephthalate, with ethylene glycol. Preferably, two molecular proportions of ethylene glycol react with one molecular proportion of the dialkyl terephthalate. More preferably,,more than two molecular proportions of ethylene glycol per molecular , proportion of the dialkyl terephthalate are used since under these conditions the initial transesteriication rea'ction occuxs more rapidly and completely. The tr~nsesterification ' reaction is conducted under,conditions of elevated temperature.
Preferably, the temperature is in the range of bet~een about the boiling tempcrature of the reaction mixture to as high as 250 C. The reaction can occur at atmospheric, sub-atmospheric 1 . . - .. .. . .
. -6- .
. .. ~ . . . ...................... ... .
. ., ... . ~ ....... .... . ........ .. . .
. . .
`:1 : - . , ~5~375 or super-atmospheric pressure. Thc bi product of the transcsterification reaction is an alkanol, for example, if dimethyl terephthalate i5 used, mbthanol i5; pro~uced.
- The alkanol is removed from the reaction product. In order to lncrease the reaction rate, many known catalysts can be employed in the transesterification reaction.
After the bis(2-hydroxy ethyl) terephthalate has been . produced it is converted to polyethylene terephthalate by heating at a temperature above the boiling point of the ethylene glycol or the reaction mixture under conditions e~ecting the removal of the glycol or water. The heating may occur at a temperature as high as 325 C, if desired.
During heating, pressure is reduced so as to pxovide rapid . .
~ distillation of the excess glycol or water. The final ; 15 polyethylene terephthalate polymer has an intrinsic viscosity, as measured in orthochlorophenol at 25 C, in excess of 0.3 deciliter per gram. More preferably, t~e intrinsic ~iscosity of the polymer ranges from about 0.4 to about 1.0 ~eciliter - : per gram, again measured in orthochlorophenol at 25 C. Still ~ . .
more preferably, the polyethylene terephthalate of the instant invention has an intrinsic viscosity of about 0.5 to about 0.7 deciliter per gram as measured in orthochlorophenol at 25 C.
In a preferred embodiment o the process of the instant invention, the polyester fïlm ~orming polymer is melted and therea~tcr extruded onto a polished revolving casting drum to ~orm a cast sheet of the polymer. Thereatcr, the film is bia~ially stretched, that is, the film is stretched in the lon~itudinal and transverse direction. Thc first stretcllillg step of the cast sheet may be in ei~her o~ these _7_ .. . .. ;... . ... ..
. ' ~ .
. . . ` : ` : `
two orthogonal directions. -The amount of stretching, to impa~t strength and toughness to the film, can range from about 3O0 to about 5.0 times the original CAst sheet dimension in both directions. Preferably, the amount of stretching is in~the range of between about 3~2 and 4 2 times the original dimension. The stretching operations are carried out at temperatures in the range of from about the second order transition temperature to below the temperature at which the polymer softens and melts.
Where necessary, the film is heat ~reated, ater stretching, for a period of time necessary to crystallize the polyester film. In the case of the preferred embodiment wherein polyethylene ~erephthalate is employed, crystallization imparts stabili~y. When polyethylene terephthalate is heat treated, it is subjected to a temperature in thè range of between about 19,3 C and 240 C and, more preferablyJ in the range of from about 215 3 C and 235ia C.
characteristics .The latex coating, which imparts antistatic~,good handle-ability, and good clarity to the film/ is applied, in a . 20 preferred embodiment, after the film is uniaxially stretched, that is, after the film is stretchecd in one direction, but before the film is stretched in the orthogonal direction.
In a more preferred embodiment, the polyester film is first stretched in the longitudinal direction, prior to coating.
~5 In thi~ preferred embodiment, a~ter lonyitudinal stretching, the film is coated by any of the well known technic~ues emp1Oyed in the art. For example, coating may be effectecl by roller coatin~, spray coatiny, slot coating or ersion coatiny. In a preferred embodiment, the polyester ~0 film is coated with a latex coatiny by mealls ~f roiler coating.
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~~ In a preferred embodiment the uniaxiaily drawn film is corona treated prior to coa~ing. That is, the film is subjected to a corona discharge by a corona discharge apparatus prior to coating. The discharge treatment decreases the hydrophobic character of the polyester film surface.
This permits the water based latex coating to more easily wet the surface and thus improve the adhesion of the coating to the surface.
Tbe latex coating disposed on the polyester film is a ; 10 latex dispersion of between about 2.75 percent and 3.25 percent by weight, based on the total weight of the latex ~ '. ' . .
; coating, of stearamidopropyldimethyl-~-hydroxy-ethylammonium ~ nitrate. In a more preferred embodiment, the concentration .. .
of ~his ammonium nitrate composition is in the range of between about 2.9 percent and 3.1 percent by weight, again ~- based on the total weight of the latex coating. In a still more preferr~d embod;ment, the concentration-of the ammonium ~itrate compound is about 3.0 percent by weight, based on the `~ total weight of the latex coating.
~he latex coating composition also includes a crosslinkable .~ . .
methylmethacrylate-ethylacrylate-methacrylamide terpolymer, ~~ present in a concentration in therange of between about ~.75 .j , . . .
percent and 1.25 percent by weight, based on the total weight of the latex coating. The copolymer is further characterized by a glass transition temperature in the range of between about 40 C
and 50 C. More preferably, the terpolymer is present in a concentration in the ranye of between about 0.9 percent and 1.1 percent by weiyht, based on the total weight of the latex coatin~. In a stiIl more preferred em~odiment of the instant invention, the terpolymer is present in a concentration of 1.0 .
. . . . . ..
' .
. ~ ~ r percent by woightt based on the total weight of the latex coating. The glass transition teml~erature of the terpolymer, in a more preferred emobidment, is in the range of between _ about 43 C and 47~ C, still more preferably, the glass transition temperature is about 45 C.
The two constituents of the latex coating are present in a weïght ratio of ~etween about 2.75:1 ana 3.25~ stear-amidopropyldimethyl-~-hydroxy-ethylammonium nitrate to methylmethacrylate-ethylacrylate-methyacryl~ide terpolymer.
In a more preEerred embodiment, the weight ra~io of the nitrate to theterpol~ner is in the range of hetween about : 2.75:1 to 3.0~
After coating, but before stretching in a direction normal to the uniaxially drawn film, the film is dried by heating ~t a temperature of the range of between about 90 C and -~ . 110 C. More preferably, the xange is between 95 C and 105 C. ,-:i , r In a preferred e~bodiment,-the thickness of the coating, after drying, on the polyester film is at least 0.003 dry pounds of coating per- thousand square feet of biaxially drawn 20 ~ilm. More preferably, the dry coating weig~t is in the range of between about 0.003 pounds to 0.007 pound~ per thousand square feet of coated film. .
In another preferred embodiment, the an~istatic coated ~ilm is coated on the opposite side w.ith a cr~sslinkable acrylic : 25 polymeric coatlng. In a preerred embodiment" the acrylic polymeric coating is an ethyl a crosslinkable ethyl acrylate-methyl methacrylate-methacrylamide terpolymer. The cDating is crosslinked .. - with an melamine formaldehyde. Preferably, th~.coating is applied by.roller coating, to the uniaxially stretche~ polyester film.
The coating is most preferably applied as a la~ex coating in .
. . .
`-10-'' ' ' ' '' . I
~5.~'75 . ' ' '- ' ' ,' - which the solids comprise between about 3 to 4~ by weight and the water constituent is between about 96~ and 97% by weight of the latex coating.
This secon~ side coating provides an anchor for acrylic and cellulosic lacquer coatings commonly employed in the reprographic industry. ~ :
~he following examples are give~ to illustrate the invention. Nothing c~ntained in the examples shouldr in any way,be interpreted as limiting the scope and spirit of the invention illustrated by these examples.
EXAMPLE 1.
Polyethylene terephthalate polymer was melted and - extruded through a slit die onto a casting drum maintained at . a temperaturP of about 20 C. The melt froze.to form a cast : 15 sheet. The cast sheet was iongitudinally st~etched at a ; dr~w ratio of approximately.3.6:1 while maintained at a temperature of~.about 80~ C. :
- film . The longitudinally drawn/was corona treated by a corona discharge apparatus and thereinafter coated with a late~
coating by reverse gravure coatin~. .
The latex coating,.coated onto the surace of the . polyester film, included 3.0~ by weiglltl based on~the total weigh~ of the coating composition, of stear2midopropyldimethyl-~-hydroxy-ethylammonium nitrate. The coati~g also included 1.0~ by weight, based on the total wei~ht c~ the coating composition, of methylmethacrylate-ethyl ac~ylate-methacrylamide terpolymer. The terpolymer is crosslinXabl~ because of the presence of a m~lamine-formaldehyde crossl.is~ng agent~
hexamethoxymethylmelamine, and is character.~zed by a glass transition temperature of 45~ C. The re~ai~Lng constituent, .. . . . . ..... . - - ~ .
5~75 ; water, represented 96~ by weight.of the latex coating.
The coating is formed by mixing first the stearamidopropyl-dimethyl-~-hydroxy-ethylammonium nitxate ~o the water - foll~wed by the terpolymer. The solids are mixed together 5 with the water by conventional mixing techniques to produce a uniform mixture which is the latex coating.
. The corona treated, longitudinally drawn, coated film - was dried at a temperature of about 100 C. Thereafter, the film was stretched, in the transverse direction, at a draw - ratio of 3.6:1 to produce a biaxially drawn film. The biaxially , drawn ~ilm was heat set at a temperature of 230 C. The . -; final antistatic coating weight range was from .003 lb. to .007 lb. per 1000 square feet of biaxially drawn ilm. The ~ total film thicXness was approximately 3 mils (0.003 lnch).
A comparison run was conductea in exactly the same manneras Example 1 to produce a ~ mil thick biaxially oriented . poly~thylene tereph~hal~te,hereinafter referred to as PET, coated film except for the composition of the latex coating.
~0 In this example the coating comprised 1% by weight,.based on the total weight of the coating composition, hereinafter referred ~o as "percent", stearamidopropyldimethyl-~-hydroxy-ethylammonium nitrate, hereinaf~er referred to as "nitrate"; 1% cr~sslinkable methyl methacrylate~ethyl acrylate-methacrylamide terpolymer having a glass transition temperature oE 45 C, hereina~ter referred to as "terpolymer"; and 98% water.
Another comparison run~ was conducted rcsulting in the foxmation o a coated film in exactly the same manner as Example 1 except that the latex coating comprised 3%.nitrate, , .-12- .
. .
.
.. . .
25.~7~
....: , ... .
3% terpolymer and 94~ water~
- EX~MPLE_4 Samples of the PET ~ilms formed in accordance with Exampfes 1-3 were tested f4r antistatic, coefficient of friction and haze properties. The antistatic property of the film was measured by a ~ualitative test. This test, pickup the ash~test, includes the steps of cutting standard sized strips of coated film, rubbing the film six times over a ' cotton fabric and placing the rubbed side of the film one i~ch above a tray filled with cigarette ashes.' Film having excellent antistatic properties will not cause any disturbance ~f the ashes. If the ashes in the tray are dis~urbed but are not drawn to the surface of the film, the film is cate-- gorized as "good". A film classified as "fair'i causes the ashes to be disturbe~ and approach the surface of the film with ' slight sticking thereto. A film classified as "poor" is so' rated because large quantities of the asX are attracted and held to the ~urfaee of the film. It is noted that the test is done a second time to the opposite side'of the film. The - 20 final elassification is the poorer of the two ra~ings if the two ratings are not the same.
''~' The test for coefficient of friction (COF), the test to determine the slip property of the film,was made in accordance with a standard test, AST~5 Method D 18~ 8. All film samples tested in accordance with this test are preconditioned in accordance with ~ST~S ~Sethod D 618,Procedure A.
The dimensionless units o coefficicnt of friction are interpreted to indicate good~slip (or handleability) ir the COF r ranges be~ween 0.3 and 0.5. Below 0.2, slip is too great.
~0 Such films telescope, that is, the films are difficult to wind . -. . ... ~... , . ... -.... . , . :
5~37~
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and are considered unsatisfac-tory. Above 0.5 slip is -inadequate. Film having a COF in excess of 0.5 is prone to blocking. When a film blocks, it does not slip at all over ; the surface to which it is in con~act.
The test for haze, the best indication of the clarity of the film, is determined by ASTM Test Method D 1003-61 Procedure A Section 7.
Haze (for 3 mil thick PET film) of 1.2~ or below is .
considered to be acceptable. Of course, th~e lower the percent haze, the clearer the ~ilm. A haze of more than 1.2% is ~ ` .
unacceptable.
In addition the latex coatings were rated as stable or unstable. A stable latex coating is one which remains an emulsion for at least one wee~. An unstable latex coating is one which breaks down into a two-phase system.
Unfort~nately, it was ~ound that PET polymer employed in Examples 1-3 was contaminated making meaningless the haze and coefficient of friction data.
The tests for films made in accordance with Examples 1-3 are summaxized in Table I.
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TABLE I
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Example Haze COF Ash Pickup Latex Number ~ Static;Kinetic At 50% RH _ t ( ) RH Stability _ _ _ 1 2.5 C~C .21 .23 Good Excellent~40%) Stable C/U .23 .27 25 2 2.5 C/C .33 .35 Good Excellent(45%~ Stable C/U .36 .37 ;~ 3 2,3 C/C .65 .43 . Good Poor (42%) Stable C/U .87 ~45 r-.
. .. , , . - . :
. ~ , . . . o 7~;
. .
NOTE 1: C = Antistatic Coated Side U = Uncoated Side , NOTE 2' Example number in this and future tables represents film ormed in accordance with example number in this specification.
NOTE 3: Parenthesized percen~age indicates the percent relative humidity at which the ash pickup test was run.
The above results indicate that the film formed in accordance with this invention, Example 1, demonstrated good antistatic properties and good latex stability.
Example 3, the film coated with 3% terpolymer had unsatisfactory - antistatic properties. In thïs respect, it is noted that whereas the ash pickup test at 50% relative humidity is good, the test at a lower relative humidity, 42%, indicated the -unaccep~ability of this coating. ~he lower the relative humidity, the more pronounced is the static propensity of polyester film and the more rigorous the test of the effecti~eness ~f the antistatic coating. It is no~ed that all relative .
humidity measurements were ta}~en at te~peratures in the ---- range o~ bet~een 72F and 74F.
As indicated abo~el the ha~e and coefficient of friction tests were meaningless due to the contamination of the polymer.
EXAMPI.E 5 Example 1 was repeated except that the side opposite the antistatic coated film side was coated with a latex coating comprising a 3% methyl methacrylate-ethyl acrylate-methacrylamide terpolymer crosslin~ed with hexametho~ymethylmel~mine and ~7~
water. The coating was applied by rever~se gravure roll to the longitudinally dra~n PET film and dried simultaneously wlth, ` ' .: ' - ,, . . ; , .
7~ .
.. . . . . -- ..... . . .
and in the same manner as the antis'tatic coating on the othex' side. The resultant product was a biaxially'drawn,3 mils ~hick ,PET film coated on one side with tne antistati,c coating described in Example 1 and on the other with the crosslinked acrylic coating described above. The dry weight of the crosslinked acrylic coating ran~ed between about .003 pound and .Q07 ~pound per 1000 square feet of biaxially stretched film.
Two comparison runs, conducted in ~he same manner as Example 5 except that the antistatic coatlng was applied from di~ferent latex coatings. In Example 6, th~ latex coating included 2% nitrate, 1% terpolymer and 97% water.
~ In Example 7 the latex coating included 3% nitrate, 2~ ter~olymer - and 95~ water. The resultant films were two side coated films differing from the film found in accordance with Ex,ample 5 only by the ~ifference in the concentration of the constituents - ~ of the antistatic coating.
- , ' EXAMPLE 8 The films made in aCcordance with Examples 5-7 were '' ' .- 20 tested for antistatic, slip and clarity properties, using the same tests as ~ere employed in Example 4. The test ' ' results are summarized below in Table II.
TABLE II
Example COF Ash Pickup I.atex Number Haze, ~ Static Kinetic At 50~ ~H At 4l~ RH Stability 1.2 A/A .~3 .44 - B/B .23 .25 Good Good Good A/B .29 .32 6 Not measured Not ~easuredFair Poor Good 7 1.2 A/A .48 .~8 B/B .23 .27 Good Good Poor , A/B .31 .35 ,, -16- ,, , . . , ~, . .
~5~b75 .
~OTE: A ~ Acrylic Coated Side .
B = ~ntistatic Coated Side It is noted that the film made in accordance with the - instant invention was acceptable in all respects. The film made in Example 6, which had a lev01 of nitrate Qutside the scope of,the inyention, exhibited unaccepta~le antistatis ~roperties.
. This film was not measured for clarity or slip. The film made - in accordance with Example 7 was acceptable in all respects except that the latex coating did/remain stable for one week.
A 3 mil biaxially oriented PET iim was made in exact accordance with the procedure and coatings employed in Example 5. That is, the antistatic latex coating included 3~ nitrate, - 1% terpolymer and 96~ water.
EXAMPLES 1~
Two additional comparisons were run in exact conformance with the procedure employed in Example 9 except for the compo-sition of the antistatic latex coating. The film made in ~ccordance with Example 10 comprised 3% nitrate and 2% terpolymer (a.s in Example 7~. The film made in accordance with Example 11 included 4~ nitrate and 1% terpolymer.
: '.
The films made in accordance with Examples ~ ere tested in accordance with the procedures discussed in Example 4.
In addition, a more quantitative test to determine the film's antistatic property was employed. This test is the measurement of the surface resistivity o~ ~he ilm. The procedure employed for measuring this value is set out in ~STM Test D257-66.
' ' .
. .
; . .. .. ..... ..
s~s A surface resistivity o~ 101~ ohms or less represents , a film having a ~ood antistatic property. A surface resis-t~vity greater than 1011 ohms is considered unacceptable.
- The results of these tests are tabulated in Table III, which appears below:
ABLE III
' ' Ash Pickup Sur~ace . Example Haze COF at at Resist. Latex ' Number % Static Kinetic 36.5~ 50% RH Ohms Stability 9 , .94 ~/A .45 .48 - ~/B .36 .40 Exc. Exc.4.7x10 Not *ested A/B .31 .42 101.04 A/A .47 .47 , il B/B .-~9 .31 Poor Exc.1.2x10 Good A/B .32 .33 111.10 A/A .48 .48 ' ' 10 ' ' B~B Block Block Exc. ~oo~ 4.2x10 Good A/B .38 .71 ~OTEl: ~ - Acrylic Coated Side ,' . . .
" B = Antistatic ~oated Side NOTE Z: The latex coating employed in Example 9 was lost and ". ' thus not tested.
I NOTE 3: All ash pickup runs were conducted at a temperature of NOTE4: Surface resistivity was measured in a room having a temperature of 78~ F and 32~36% RH.
NOTE 5: Surface resistivity reported is the average of ~wo readings measured on the antistatic ¢oated side).
The above results confirm the excelle~t results obtained, in the test of the ilm made in Example 9,within the scope of this invention. The COInpariSOn ilm,made i~ accordance with E~ample 10,had unacceptable antistatic cha~cteristics. The .
. , .~, ~ .
... . , ., .. " :, . .. .
~ 5~5 .
.. . .. ~ . ..
ash pickup at 36.5~ relative humidity was unacceptable on the acrylic coated side. It is noted that the surface t~
resistivity data confirms the conclusion drawn from the ash pickup test. In conformance, it is noted . . , that ash pic~up, at 36.5% RE~, was rated good on the antistatic coated side. As indicated above the classification reported .
. is the lowex of the two ratings for the two sides of the film.
The film made in accordance with Example llwas unaccep-~able based on its unacceptable slip properties.
1~ . EX~MPLES 13-15 A set of Pxperiments were run to determine the effect of _ a coating similar to that disclosed in U.S. Patent 3,264,136.
- In that patent an example is given of a PET film coated with a coating dispersion including 0.14% by weight of polymethyl ~5 me~hacrylate and 0.2% by volume of stearamidopropyl-dimethyl-B-hydroxyethyl ammonium nitrate, the same component used in the instant invention and denoted in the Examples as "nitrate".
A Yolume concentration of 0.2% is roughly equivalent to a weight concentration of between 0.2 and 0.3~ since the specific --- 20 gravity of the nitrate is close to 1.
To determine the effectiveness of the above composition, Example 13 was run in conformance with the procedure enurnerated in Example 1.
At the same time, another latex coating including 0.5~ by weight of polymethyl methacrylate, hased on the total weignt :.
o~ the compositioil, and 0.5% nitrate was employed in the -~formation of a biaxially oriented, coated 3 ~il~PET :~
film. This run, E~ample 1~ differed ~rom Exan~ple 13 only to the extent that a different coating was emplo~ed.
~ ' , --19~
. .
.
5~7~i ,.. .: ,, . . ' , .
third coating composition was employed to produce a third P~T film. This film was proc'essed in accordance with the same procedure employed in Examples 13 and 14 except that the latex coating comprised 1% polymethyl methacrylate, 3~ nitrate and 96% water. The experiment resulting i.n the productionof this P~T film is denoted as'Example.:15. ,:
, . _ .. .... .. .. . . . . . .
~ r EXAMPLE 16 ..
The films formed in accordance with Examples 13-15 were tested for antistaticj slip and haze properties as well as latex stability. The xesults of these tests are summarized in Table IV.
TABLE IV
Example Haze COF . Ash Pickup ~atex Number ~ Static ~inetic at 40~ RH, 78-79~ F Stability - ~ .
' 13.94 C/C .73 .S~ '' , . . . C/U Blocke~ Blocked Good . Good 1~.74 C~C .37 .40.
. .,: .'.. C/~ .34 .39 Poor Poor .
. ,.. 2~ 15 1.62 C/C .28.82 Good Poor C~U .~4 .45 , . ' . NOTE: C = Antistatic Coated Side : U ~ Uncoated Side The tabulated results above yield one anomalous result.,.
For unknown reasons the,,film of Examplc 13 had unacceptable slip propexties... In all othe~.'respects the fil~l and the latex sta- ' .
; bility of the coating used to coat that fi~m was acceptable.
Example 14 illustrates the unacceptabi~ity of a latex coating having as little as 0.5~ by weight ~itrate, even if - 30 polymethyl methacrylate is,used as the sec~nd component. As ~20- .
.
; t J
~5~5 !;
. . o . ., -v . - I
~ndicat~d by the ash pic~up-test, the antistatic properties of this coating, employing everl a higher concentxation of nitrate than suggested by the ~136 patent, is unacce~table.
This also in spite of ~he fact t~at the polymethylmethacrylate is similarly increased in concentration closer to the range employed by the terpolymer of the instant invention.
Example 15 illustrates the unacceptability of employing polymethylmethacrylate instead of the terpolymer. The clarity o~ this film is unacceptable. It is noted that but for the substitution of polymethylmethacrylate for the terpolymer this film would be within the scope of this invention.
It is also emphasized that the latex coating employing polymethylmethacrylate is unacceptable because of the unstability o the coating. The latex coatings in Example 14 ~0.5~ poly-methylmethacrylate) and Example 15 (1.0~ polym-ethylmethacrylate) both coagulated before one week. - Ç
..
- Six experiments were run to determine the effect of the ; weight ratio of nitrate to terpo~ymer. This was accomplished by producing biaxially stretched PET film in accordance with the procedure enumerated in Example 1 except for the composition of the antistatic latex coating compo~ition. The composition o the coating, in every case, included lt by weight of the terpolymer. The six runs varied in the concentration oE the nitrate. Example 17 included 2. 006 nitrate by weight and in each succeeding example the nitrate concentration was increased by 0.25% so that Example 23 included 3.25% nitrate. Thus, the ratio o~ nitrate to terpolymer varied from 2.00 in Example 17 to 3.25 in Example 23. It is emphasized that the side opposite the antistatic coated side remained uncoated.
..
.
._. ~1 ,, S~75 EX~MPLE 23 .. . . ~ . .
Th~ samples formed in accordance with Examples 17-23 were tested to determine antistatic, sl.ip and clarity proper~
- ties of the one side coated 3 mil thick biaxially oriented PET. In all cases the haze values of all the ~ilms were acceptable.
. The ash pickup test of all the samples run at 37~ relative - humidity and 78 F-79 F tested as good. Furthermore, the ~ latex stability for all coating samples employed in t~is test : - 10 was satisfactory. The remaining results,which includea a :: repeat of the ash pickup test at a lower relative humidity appear below in Table V.
TABLE V
Example Ratio ~Nitrate/ - ~OF
Number Terpolymer Ash Pickup At ~RH Static Klnetic 17 2.00 Poor31.5- C/C .30 .26 . , CJu .33 .~2 1~ 2.25 Poor . 31.5C/C .25 .27 ~ V .33 .~4 19 2.5~ Good 31.5CjC .27 .32 Poor 31.0C/U .35 .44
" . , . . , . : .
BACKGROUND OF THE DI SCLOSURE
.
Field of the Invention ~ his invention is directed to an improved polyester film having excellent antistatic properties and the process for producing said film. More specifically, the instant invention is directed ~o a polyester film hav~ng improved antistatic properties in combination with improved slip properties and the process for producing the film. Still more specifically, the instant invention is directed to a 10 polyethylene terephthalate film coated with a latex coating hich imparts excellent antistatic and slip properties and the process for producing the film.
. . . . .
- Summary of the Prior Art -The growth of microfilm and magnetic tape markets has significantly increased the utilization of polyester film as supports for these products. However, polyester film becomes electrostatically charged, especially at low relative humidity. This electrostatic charge attracts not only dust and pther contaminants, but, a~aitionally, attracts other polyester film supports. For instance, electrostatic forces . interfere in the collating, sorting and developing of micro-fiche cards by causing the cards to stick to~ether.
To overcome this serious problem, antis~cltic polyester ilms have been developed. ~ntistatic poly~ter films are ~5 usually formed by the application of an ant~tatic coating onto the surface of the polyester film. Ma~ of these coatings have successfully reduced the electrostatic properties of the polyester film to satisfactorily low levels. HoweYer, many of these coatin~s cause bloc~ing. That is, th~ pol~ester film .
~. -2- .
. .-.
coated wi~h an antistatic layer has a coefficient of friction hi~h enough so that one layer of the film does not slip over another or over rollers and other equipment over which - the film moves duriny operation.
S Another problem arising from the coating o~ an antistatic layer onto the surface of a polyester film is the decreased clarity resulting therefrom. This property, usually reported . as haze, is very important in microfilm applications~ Microfilm must be readable. Light is projected through the film so that the viewer may read the information printed on the film. Poor clarity results in fuzziness and difficulty in reading because of loss of light intensity.
The above discussion indicates the importance of polyester ~ilm having good antistatic propexties, as well as good slip, 1~ or handleabili~y, and clarity~ Thus it is critical that the antistatîc coating provide all three of these properties.
Alt~ough the prior art includes disclosures directed to anti-static coating on polyester films none of them produce films - properties h~ving the combination of good antistatic, slip and clarity/.
V.S. Patent 4,089,997 issued to Van Paesschen et ai includes a disclosure of stearamidopropyldimethyl-~-hydroxy-ethylammonium nitrate. ~owever, the disclosure in the '997 patent includes additional constituents, diferent from those in the instant invention' which do not prod~ce the excellent combination of antistatic, slip and clarity properties.
Not only are the constituents present ~ the antistatic coating critical to the fil~n's antistatic, s~p and clarity properties, but moreovex, the concentrations of these material are similarly o~ ~r~at importance. For inst~nce, ~.S. Patent 3,264,136 issucd to Hcd~e, discloses a coatm~ which includes . .,, O
.. .. . .... ..
, .._ ... .. .
0.2 percent bv volume of stearamidopropyldimethyl.B-hydro~.y-ethylammonium nitrate in combinatio~ with the radditional con-stituents, polymethylmethacrylate. This combination sf constituents did not produce the combinatlon ~f antistatic, 5 slip and clarity properties necessary for utilization in polyester film supported microfilm and magnetic tapes.
An additional requirement in antistatic film technology is not directed to the properties of the film. It is not enough that a latex coating provide the important properties discussed above. The latex coating must be stable. That is, the latex coating cannot precipitate out on standing, to form a two-phase system, for at least one week. This property, satisfactory pot life, is necessary for commercial operation of a coating process. One can ill afford to devise an .antistatic coating providing excellent antistatic, slip. and : properties clarity/which does not stay emulsified long enough to coat a - suitable length of film.
, SUM~RY OF THE INVENTION
~0 The instant invention is directed to a ~olyester film support which not only has outstanding antistatic properties but also very good handleability, that is, good slip properties, as well as excellent clarity. These properties are provided by a latex coating which additionally has excel-lent pot life.
In accordance with the instant inventicn, a polyester film is provicled. The film, which is biaxially oriented, is coated Oll one side with a latex coating. rrhe latex coating includes stearamidopropyldimethyl-~-hydroxyethylammonium nitrate pres~nt in a concentration in the ram~e of between . .
"
f ~
~125~75 ` . .- , , . . .......................... : .. ~
about 2.75 and 3.25 percent by weight, based on the total weight of the latex coating. Additionally, the coating includes a crosslinked methylmethacrylate-ethy~acrylate-~ methacrylamide terpolymer, having a glass transition temper-ature in the range of between about 40 C and 5~ C, presentin a concentration in the range of between about 0.75 percent and 1.25 percent by weight, based on t~e total weight of the - latex coating. The weight ratio of the two constituents in the Iatex coating, that is, the ratio of the nitrate to the terpolymer, is in the range of between about 2.75.1 and 3.25:1.
In accordance with the process for forming this film, a uniaxially drawn polyester film is coated with a latex coating, de~ined above. The uniaxially drawn polyester film is heated by exposure to ele~ated temperatures whereby ~ lS ~he water in the latex coating is driven off. The dried - latex coated uniaxially drawn film is then stretched, in a direction normal to that of the uniaxially ~rawn film, to form the antistatic, biaxially oriented polyester ~ilm. ~-- . , ' . , 20 DETAILED DESCRIPTIO~
Polyester film, upon which the antistatic layer is disposed, may be formed from any thermoplastic film forming poly~ster producea by condensing a dicarboxylic acid or a lower alkyl diester thereof wi~h a glycol. Among the dicarboxylic acids or their lower alkyl diesters within the contemplation o~ this inventian include terephthalic;
isophthalic; phthalic; 2~5,2,6; or 2,7-napth~lene dicarboxylic;
succinic; sebacic, adipic; azelaic, bibenzoi~; and hexahydro-terephthalic acids; and bis~p carbo~y phenox~ ethane. One or more o~ these dicarboxylic acids or their lo~er al~yl diesters is , . O
_5-. . . .. .
: : ' ;~
~5~75 : .
... . ..
reacted with one or more glycols which include ethylenç
, glycol; 1,3-pro~anediol; 1,4-butanediol; neopentyl glycol or 1,4-cyclohexanedimethanol. In that one or ~ore diesters - may be reacted with one or more glycols, the polyestex ilm ' of this invention is not limited to homopolyesters but also includes copolyesters. .
, Of the film forming polyesters within the contemplation of this invention the most preferred is polyethylene tereph-thal~te. Polyethylene terephthalate film is formed from a polymer produced by polymerization of bis~2-hydroxy ethyl) ~'' tèrephthalate. Bis (2-hydroxy ethyl) terephthalate is itself formed as an intermediate by one of two different methoas.
One method for producing bis(2-hydroxy ethyl) -terephthalate --is ~y direct esterification of terephthalic acid,and ,ethylene : 15 ~lycoi as described in U.S. Patent 3L050,533. In this method ~:, . .
the bi-product of the reaction is water which is distilled - from,'the reaction product. A second method for producing . bis (2-hydroxy ethyl) texephthalate is by transesterification - of a dialkyl ester of terephthalic acid, preferably dimethyl terephthalate, with ethylene glycol. Preferably, two molecular proportions of ethylene glycol react with one molecular proportion of the dialkyl terephthalate. More preferably,,more than two molecular proportions of ethylene glycol per molecular , proportion of the dialkyl terephthalate are used since under these conditions the initial transesteriication rea'ction occuxs more rapidly and completely. The tr~nsesterification ' reaction is conducted under,conditions of elevated temperature.
Preferably, the temperature is in the range of bet~een about the boiling tempcrature of the reaction mixture to as high as 250 C. The reaction can occur at atmospheric, sub-atmospheric 1 . . - .. .. . .
. -6- .
. .. ~ . . . ...................... ... .
. ., ... . ~ ....... .... . ........ .. . .
. . .
`:1 : - . , ~5~375 or super-atmospheric pressure. Thc bi product of the transcsterification reaction is an alkanol, for example, if dimethyl terephthalate i5 used, mbthanol i5; pro~uced.
- The alkanol is removed from the reaction product. In order to lncrease the reaction rate, many known catalysts can be employed in the transesterification reaction.
After the bis(2-hydroxy ethyl) terephthalate has been . produced it is converted to polyethylene terephthalate by heating at a temperature above the boiling point of the ethylene glycol or the reaction mixture under conditions e~ecting the removal of the glycol or water. The heating may occur at a temperature as high as 325 C, if desired.
During heating, pressure is reduced so as to pxovide rapid . .
~ distillation of the excess glycol or water. The final ; 15 polyethylene terephthalate polymer has an intrinsic viscosity, as measured in orthochlorophenol at 25 C, in excess of 0.3 deciliter per gram. More preferably, t~e intrinsic ~iscosity of the polymer ranges from about 0.4 to about 1.0 ~eciliter - : per gram, again measured in orthochlorophenol at 25 C. Still ~ . .
more preferably, the polyethylene terephthalate of the instant invention has an intrinsic viscosity of about 0.5 to about 0.7 deciliter per gram as measured in orthochlorophenol at 25 C.
In a preferred embodiment o the process of the instant invention, the polyester fïlm ~orming polymer is melted and therea~tcr extruded onto a polished revolving casting drum to ~orm a cast sheet of the polymer. Thereatcr, the film is bia~ially stretched, that is, the film is stretched in the lon~itudinal and transverse direction. Thc first stretcllillg step of the cast sheet may be in ei~her o~ these _7_ .. . .. ;... . ... ..
. ' ~ .
. . . ` : ` : `
two orthogonal directions. -The amount of stretching, to impa~t strength and toughness to the film, can range from about 3O0 to about 5.0 times the original CAst sheet dimension in both directions. Preferably, the amount of stretching is in~the range of between about 3~2 and 4 2 times the original dimension. The stretching operations are carried out at temperatures in the range of from about the second order transition temperature to below the temperature at which the polymer softens and melts.
Where necessary, the film is heat ~reated, ater stretching, for a period of time necessary to crystallize the polyester film. In the case of the preferred embodiment wherein polyethylene ~erephthalate is employed, crystallization imparts stabili~y. When polyethylene terephthalate is heat treated, it is subjected to a temperature in thè range of between about 19,3 C and 240 C and, more preferablyJ in the range of from about 215 3 C and 235ia C.
characteristics .The latex coating, which imparts antistatic~,good handle-ability, and good clarity to the film/ is applied, in a . 20 preferred embodiment, after the film is uniaxially stretched, that is, after the film is stretchecd in one direction, but before the film is stretched in the orthogonal direction.
In a more preferred embodiment, the polyester film is first stretched in the longitudinal direction, prior to coating.
~5 In thi~ preferred embodiment, a~ter lonyitudinal stretching, the film is coated by any of the well known technic~ues emp1Oyed in the art. For example, coating may be effectecl by roller coatin~, spray coatiny, slot coating or ersion coatiny. In a preferred embodiment, the polyester ~0 film is coated with a latex coatiny by mealls ~f roiler coating.
, --- 8- ;
. . .. .
.
.. , ~
~ r~ ~ ~
,............... .. . . .
~~ In a preferred embodiment the uniaxiaily drawn film is corona treated prior to coa~ing. That is, the film is subjected to a corona discharge by a corona discharge apparatus prior to coating. The discharge treatment decreases the hydrophobic character of the polyester film surface.
This permits the water based latex coating to more easily wet the surface and thus improve the adhesion of the coating to the surface.
Tbe latex coating disposed on the polyester film is a ; 10 latex dispersion of between about 2.75 percent and 3.25 percent by weight, based on the total weight of the latex ~ '. ' . .
; coating, of stearamidopropyldimethyl-~-hydroxy-ethylammonium ~ nitrate. In a more preferred embodiment, the concentration .. .
of ~his ammonium nitrate composition is in the range of between about 2.9 percent and 3.1 percent by weight, again ~- based on the total weight of the latex coating. In a still more preferr~d embod;ment, the concentration-of the ammonium ~itrate compound is about 3.0 percent by weight, based on the `~ total weight of the latex coating.
~he latex coating composition also includes a crosslinkable .~ . .
methylmethacrylate-ethylacrylate-methacrylamide terpolymer, ~~ present in a concentration in therange of between about ~.75 .j , . . .
percent and 1.25 percent by weight, based on the total weight of the latex coating. The copolymer is further characterized by a glass transition temperature in the range of between about 40 C
and 50 C. More preferably, the terpolymer is present in a concentration in the ranye of between about 0.9 percent and 1.1 percent by weiyht, based on the total weight of the latex coatin~. In a stiIl more preferred em~odiment of the instant invention, the terpolymer is present in a concentration of 1.0 .
. . . . . ..
' .
. ~ ~ r percent by woightt based on the total weight of the latex coating. The glass transition teml~erature of the terpolymer, in a more preferred emobidment, is in the range of between _ about 43 C and 47~ C, still more preferably, the glass transition temperature is about 45 C.
The two constituents of the latex coating are present in a weïght ratio of ~etween about 2.75:1 ana 3.25~ stear-amidopropyldimethyl-~-hydroxy-ethylammonium nitrate to methylmethacrylate-ethylacrylate-methyacryl~ide terpolymer.
In a more preEerred embodiment, the weight ra~io of the nitrate to theterpol~ner is in the range of hetween about : 2.75:1 to 3.0~
After coating, but before stretching in a direction normal to the uniaxially drawn film, the film is dried by heating ~t a temperature of the range of between about 90 C and -~ . 110 C. More preferably, the xange is between 95 C and 105 C. ,-:i , r In a preferred e~bodiment,-the thickness of the coating, after drying, on the polyester film is at least 0.003 dry pounds of coating per- thousand square feet of biaxially drawn 20 ~ilm. More preferably, the dry coating weig~t is in the range of between about 0.003 pounds to 0.007 pound~ per thousand square feet of coated film. .
In another preferred embodiment, the an~istatic coated ~ilm is coated on the opposite side w.ith a cr~sslinkable acrylic : 25 polymeric coatlng. In a preerred embodiment" the acrylic polymeric coating is an ethyl a crosslinkable ethyl acrylate-methyl methacrylate-methacrylamide terpolymer. The cDating is crosslinked .. - with an melamine formaldehyde. Preferably, th~.coating is applied by.roller coating, to the uniaxially stretche~ polyester film.
The coating is most preferably applied as a la~ex coating in .
. . .
`-10-'' ' ' ' '' . I
~5.~'75 . ' ' '- ' ' ,' - which the solids comprise between about 3 to 4~ by weight and the water constituent is between about 96~ and 97% by weight of the latex coating.
This secon~ side coating provides an anchor for acrylic and cellulosic lacquer coatings commonly employed in the reprographic industry. ~ :
~he following examples are give~ to illustrate the invention. Nothing c~ntained in the examples shouldr in any way,be interpreted as limiting the scope and spirit of the invention illustrated by these examples.
EXAMPLE 1.
Polyethylene terephthalate polymer was melted and - extruded through a slit die onto a casting drum maintained at . a temperaturP of about 20 C. The melt froze.to form a cast : 15 sheet. The cast sheet was iongitudinally st~etched at a ; dr~w ratio of approximately.3.6:1 while maintained at a temperature of~.about 80~ C. :
- film . The longitudinally drawn/was corona treated by a corona discharge apparatus and thereinafter coated with a late~
coating by reverse gravure coatin~. .
The latex coating,.coated onto the surace of the . polyester film, included 3.0~ by weiglltl based on~the total weigh~ of the coating composition, of stear2midopropyldimethyl-~-hydroxy-ethylammonium nitrate. The coati~g also included 1.0~ by weight, based on the total wei~ht c~ the coating composition, of methylmethacrylate-ethyl ac~ylate-methacrylamide terpolymer. The terpolymer is crosslinXabl~ because of the presence of a m~lamine-formaldehyde crossl.is~ng agent~
hexamethoxymethylmelamine, and is character.~zed by a glass transition temperature of 45~ C. The re~ai~Lng constituent, .. . . . . ..... . - - ~ .
5~75 ; water, represented 96~ by weight.of the latex coating.
The coating is formed by mixing first the stearamidopropyl-dimethyl-~-hydroxy-ethylammonium nitxate ~o the water - foll~wed by the terpolymer. The solids are mixed together 5 with the water by conventional mixing techniques to produce a uniform mixture which is the latex coating.
. The corona treated, longitudinally drawn, coated film - was dried at a temperature of about 100 C. Thereafter, the film was stretched, in the transverse direction, at a draw - ratio of 3.6:1 to produce a biaxially drawn film. The biaxially , drawn ~ilm was heat set at a temperature of 230 C. The . -; final antistatic coating weight range was from .003 lb. to .007 lb. per 1000 square feet of biaxially drawn ilm. The ~ total film thicXness was approximately 3 mils (0.003 lnch).
A comparison run was conductea in exactly the same manneras Example 1 to produce a ~ mil thick biaxially oriented . poly~thylene tereph~hal~te,hereinafter referred to as PET, coated film except for the composition of the latex coating.
~0 In this example the coating comprised 1% by weight,.based on the total weight of the coating composition, hereinafter referred ~o as "percent", stearamidopropyldimethyl-~-hydroxy-ethylammonium nitrate, hereinaf~er referred to as "nitrate"; 1% cr~sslinkable methyl methacrylate~ethyl acrylate-methacrylamide terpolymer having a glass transition temperature oE 45 C, hereina~ter referred to as "terpolymer"; and 98% water.
Another comparison run~ was conducted rcsulting in the foxmation o a coated film in exactly the same manner as Example 1 except that the latex coating comprised 3%.nitrate, , .-12- .
. .
.
.. . .
25.~7~
....: , ... .
3% terpolymer and 94~ water~
- EX~MPLE_4 Samples of the PET ~ilms formed in accordance with Exampfes 1-3 were tested f4r antistatic, coefficient of friction and haze properties. The antistatic property of the film was measured by a ~ualitative test. This test, pickup the ash~test, includes the steps of cutting standard sized strips of coated film, rubbing the film six times over a ' cotton fabric and placing the rubbed side of the film one i~ch above a tray filled with cigarette ashes.' Film having excellent antistatic properties will not cause any disturbance ~f the ashes. If the ashes in the tray are dis~urbed but are not drawn to the surface of the film, the film is cate-- gorized as "good". A film classified as "fair'i causes the ashes to be disturbe~ and approach the surface of the film with ' slight sticking thereto. A film classified as "poor" is so' rated because large quantities of the asX are attracted and held to the ~urfaee of the film. It is noted that the test is done a second time to the opposite side'of the film. The - 20 final elassification is the poorer of the two ra~ings if the two ratings are not the same.
''~' The test for coefficient of friction (COF), the test to determine the slip property of the film,was made in accordance with a standard test, AST~5 Method D 18~ 8. All film samples tested in accordance with this test are preconditioned in accordance with ~ST~S ~Sethod D 618,Procedure A.
The dimensionless units o coefficicnt of friction are interpreted to indicate good~slip (or handleability) ir the COF r ranges be~ween 0.3 and 0.5. Below 0.2, slip is too great.
~0 Such films telescope, that is, the films are difficult to wind . -. . ... ~... , . ... -.... . , . :
5~37~
J~-o~ ''-- ' '' ,.
and are considered unsatisfac-tory. Above 0.5 slip is -inadequate. Film having a COF in excess of 0.5 is prone to blocking. When a film blocks, it does not slip at all over ; the surface to which it is in con~act.
The test for haze, the best indication of the clarity of the film, is determined by ASTM Test Method D 1003-61 Procedure A Section 7.
Haze (for 3 mil thick PET film) of 1.2~ or below is .
considered to be acceptable. Of course, th~e lower the percent haze, the clearer the ~ilm. A haze of more than 1.2% is ~ ` .
unacceptable.
In addition the latex coatings were rated as stable or unstable. A stable latex coating is one which remains an emulsion for at least one wee~. An unstable latex coating is one which breaks down into a two-phase system.
Unfort~nately, it was ~ound that PET polymer employed in Examples 1-3 was contaminated making meaningless the haze and coefficient of friction data.
The tests for films made in accordance with Examples 1-3 are summaxized in Table I.
. ., . , ~
TABLE I
.
Example Haze COF Ash Pickup Latex Number ~ Static;Kinetic At 50% RH _ t ( ) RH Stability _ _ _ 1 2.5 C~C .21 .23 Good Excellent~40%) Stable C/U .23 .27 25 2 2.5 C/C .33 .35 Good Excellent(45%~ Stable C/U .36 .37 ;~ 3 2,3 C/C .65 .43 . Good Poor (42%) Stable C/U .87 ~45 r-.
. .. , , . - . :
. ~ , . . . o 7~;
. .
NOTE 1: C = Antistatic Coated Side U = Uncoated Side , NOTE 2' Example number in this and future tables represents film ormed in accordance with example number in this specification.
NOTE 3: Parenthesized percen~age indicates the percent relative humidity at which the ash pickup test was run.
The above results indicate that the film formed in accordance with this invention, Example 1, demonstrated good antistatic properties and good latex stability.
Example 3, the film coated with 3% terpolymer had unsatisfactory - antistatic properties. In thïs respect, it is noted that whereas the ash pickup test at 50% relative humidity is good, the test at a lower relative humidity, 42%, indicated the -unaccep~ability of this coating. ~he lower the relative humidity, the more pronounced is the static propensity of polyester film and the more rigorous the test of the effecti~eness ~f the antistatic coating. It is no~ed that all relative .
humidity measurements were ta}~en at te~peratures in the ---- range o~ bet~een 72F and 74F.
As indicated abo~el the ha~e and coefficient of friction tests were meaningless due to the contamination of the polymer.
EXAMPI.E 5 Example 1 was repeated except that the side opposite the antistatic coated film side was coated with a latex coating comprising a 3% methyl methacrylate-ethyl acrylate-methacrylamide terpolymer crosslin~ed with hexametho~ymethylmel~mine and ~7~
water. The coating was applied by rever~se gravure roll to the longitudinally dra~n PET film and dried simultaneously wlth, ` ' .: ' - ,, . . ; , .
7~ .
.. . . . . -- ..... . . .
and in the same manner as the antis'tatic coating on the othex' side. The resultant product was a biaxially'drawn,3 mils ~hick ,PET film coated on one side with tne antistati,c coating described in Example 1 and on the other with the crosslinked acrylic coating described above. The dry weight of the crosslinked acrylic coating ran~ed between about .003 pound and .Q07 ~pound per 1000 square feet of biaxially stretched film.
Two comparison runs, conducted in ~he same manner as Example 5 except that the antistatic coatlng was applied from di~ferent latex coatings. In Example 6, th~ latex coating included 2% nitrate, 1% terpolymer and 97% water.
~ In Example 7 the latex coating included 3% nitrate, 2~ ter~olymer - and 95~ water. The resultant films were two side coated films differing from the film found in accordance with Ex,ample 5 only by the ~ifference in the concentration of the constituents - ~ of the antistatic coating.
- , ' EXAMPLE 8 The films made in aCcordance with Examples 5-7 were '' ' .- 20 tested for antistatic, slip and clarity properties, using the same tests as ~ere employed in Example 4. The test ' ' results are summarized below in Table II.
TABLE II
Example COF Ash Pickup I.atex Number Haze, ~ Static Kinetic At 50~ ~H At 4l~ RH Stability 1.2 A/A .~3 .44 - B/B .23 .25 Good Good Good A/B .29 .32 6 Not measured Not ~easuredFair Poor Good 7 1.2 A/A .48 .~8 B/B .23 .27 Good Good Poor , A/B .31 .35 ,, -16- ,, , . . , ~, . .
~5~b75 .
~OTE: A ~ Acrylic Coated Side .
B = ~ntistatic Coated Side It is noted that the film made in accordance with the - instant invention was acceptable in all respects. The film made in Example 6, which had a lev01 of nitrate Qutside the scope of,the inyention, exhibited unaccepta~le antistatis ~roperties.
. This film was not measured for clarity or slip. The film made - in accordance with Example 7 was acceptable in all respects except that the latex coating did/remain stable for one week.
A 3 mil biaxially oriented PET iim was made in exact accordance with the procedure and coatings employed in Example 5. That is, the antistatic latex coating included 3~ nitrate, - 1% terpolymer and 96~ water.
EXAMPLES 1~
Two additional comparisons were run in exact conformance with the procedure employed in Example 9 except for the compo-sition of the antistatic latex coating. The film made in ~ccordance with Example 10 comprised 3% nitrate and 2% terpolymer (a.s in Example 7~. The film made in accordance with Example 11 included 4~ nitrate and 1% terpolymer.
: '.
The films made in accordance with Examples ~ ere tested in accordance with the procedures discussed in Example 4.
In addition, a more quantitative test to determine the film's antistatic property was employed. This test is the measurement of the surface resistivity o~ ~he ilm. The procedure employed for measuring this value is set out in ~STM Test D257-66.
' ' .
. .
; . .. .. ..... ..
s~s A surface resistivity o~ 101~ ohms or less represents , a film having a ~ood antistatic property. A surface resis-t~vity greater than 1011 ohms is considered unacceptable.
- The results of these tests are tabulated in Table III, which appears below:
ABLE III
' ' Ash Pickup Sur~ace . Example Haze COF at at Resist. Latex ' Number % Static Kinetic 36.5~ 50% RH Ohms Stability 9 , .94 ~/A .45 .48 - ~/B .36 .40 Exc. Exc.4.7x10 Not *ested A/B .31 .42 101.04 A/A .47 .47 , il B/B .-~9 .31 Poor Exc.1.2x10 Good A/B .32 .33 111.10 A/A .48 .48 ' ' 10 ' ' B~B Block Block Exc. ~oo~ 4.2x10 Good A/B .38 .71 ~OTEl: ~ - Acrylic Coated Side ,' . . .
" B = Antistatic ~oated Side NOTE Z: The latex coating employed in Example 9 was lost and ". ' thus not tested.
I NOTE 3: All ash pickup runs were conducted at a temperature of NOTE4: Surface resistivity was measured in a room having a temperature of 78~ F and 32~36% RH.
NOTE 5: Surface resistivity reported is the average of ~wo readings measured on the antistatic ¢oated side).
The above results confirm the excelle~t results obtained, in the test of the ilm made in Example 9,within the scope of this invention. The COInpariSOn ilm,made i~ accordance with E~ample 10,had unacceptable antistatic cha~cteristics. The .
. , .~, ~ .
... . , ., .. " :, . .. .
~ 5~5 .
.. . .. ~ . ..
ash pickup at 36.5~ relative humidity was unacceptable on the acrylic coated side. It is noted that the surface t~
resistivity data confirms the conclusion drawn from the ash pickup test. In conformance, it is noted . . , that ash pic~up, at 36.5% RE~, was rated good on the antistatic coated side. As indicated above the classification reported .
. is the lowex of the two ratings for the two sides of the film.
The film made in accordance with Example llwas unaccep-~able based on its unacceptable slip properties.
1~ . EX~MPLES 13-15 A set of Pxperiments were run to determine the effect of _ a coating similar to that disclosed in U.S. Patent 3,264,136.
- In that patent an example is given of a PET film coated with a coating dispersion including 0.14% by weight of polymethyl ~5 me~hacrylate and 0.2% by volume of stearamidopropyl-dimethyl-B-hydroxyethyl ammonium nitrate, the same component used in the instant invention and denoted in the Examples as "nitrate".
A Yolume concentration of 0.2% is roughly equivalent to a weight concentration of between 0.2 and 0.3~ since the specific --- 20 gravity of the nitrate is close to 1.
To determine the effectiveness of the above composition, Example 13 was run in conformance with the procedure enurnerated in Example 1.
At the same time, another latex coating including 0.5~ by weight of polymethyl methacrylate, hased on the total weignt :.
o~ the compositioil, and 0.5% nitrate was employed in the -~formation of a biaxially oriented, coated 3 ~il~PET :~
film. This run, E~ample 1~ differed ~rom Exan~ple 13 only to the extent that a different coating was emplo~ed.
~ ' , --19~
. .
.
5~7~i ,.. .: ,, . . ' , .
third coating composition was employed to produce a third P~T film. This film was proc'essed in accordance with the same procedure employed in Examples 13 and 14 except that the latex coating comprised 1% polymethyl methacrylate, 3~ nitrate and 96% water. The experiment resulting i.n the productionof this P~T film is denoted as'Example.:15. ,:
, . _ .. .... .. .. . . . . . .
~ r EXAMPLE 16 ..
The films formed in accordance with Examples 13-15 were tested for antistaticj slip and haze properties as well as latex stability. The xesults of these tests are summarized in Table IV.
TABLE IV
Example Haze COF . Ash Pickup ~atex Number ~ Static ~inetic at 40~ RH, 78-79~ F Stability - ~ .
' 13.94 C/C .73 .S~ '' , . . . C/U Blocke~ Blocked Good . Good 1~.74 C~C .37 .40.
. .,: .'.. C/~ .34 .39 Poor Poor .
. ,.. 2~ 15 1.62 C/C .28.82 Good Poor C~U .~4 .45 , . ' . NOTE: C = Antistatic Coated Side : U ~ Uncoated Side The tabulated results above yield one anomalous result.,.
For unknown reasons the,,film of Examplc 13 had unacceptable slip propexties... In all othe~.'respects the fil~l and the latex sta- ' .
; bility of the coating used to coat that fi~m was acceptable.
Example 14 illustrates the unacceptabi~ity of a latex coating having as little as 0.5~ by weight ~itrate, even if - 30 polymethyl methacrylate is,used as the sec~nd component. As ~20- .
.
; t J
~5~5 !;
. . o . ., -v . - I
~ndicat~d by the ash pic~up-test, the antistatic properties of this coating, employing everl a higher concentxation of nitrate than suggested by the ~136 patent, is unacce~table.
This also in spite of ~he fact t~at the polymethylmethacrylate is similarly increased in concentration closer to the range employed by the terpolymer of the instant invention.
Example 15 illustrates the unacceptability of employing polymethylmethacrylate instead of the terpolymer. The clarity o~ this film is unacceptable. It is noted that but for the substitution of polymethylmethacrylate for the terpolymer this film would be within the scope of this invention.
It is also emphasized that the latex coating employing polymethylmethacrylate is unacceptable because of the unstability o the coating. The latex coatings in Example 14 ~0.5~ poly-methylmethacrylate) and Example 15 (1.0~ polym-ethylmethacrylate) both coagulated before one week. - Ç
..
- Six experiments were run to determine the effect of the ; weight ratio of nitrate to terpo~ymer. This was accomplished by producing biaxially stretched PET film in accordance with the procedure enumerated in Example 1 except for the composition of the antistatic latex coating compo~ition. The composition o the coating, in every case, included lt by weight of the terpolymer. The six runs varied in the concentration oE the nitrate. Example 17 included 2. 006 nitrate by weight and in each succeeding example the nitrate concentration was increased by 0.25% so that Example 23 included 3.25% nitrate. Thus, the ratio o~ nitrate to terpolymer varied from 2.00 in Example 17 to 3.25 in Example 23. It is emphasized that the side opposite the antistatic coated side remained uncoated.
..
.
._. ~1 ,, S~75 EX~MPLE 23 .. . . ~ . .
Th~ samples formed in accordance with Examples 17-23 were tested to determine antistatic, sl.ip and clarity proper~
- ties of the one side coated 3 mil thick biaxially oriented PET. In all cases the haze values of all the ~ilms were acceptable.
. The ash pickup test of all the samples run at 37~ relative - humidity and 78 F-79 F tested as good. Furthermore, the ~ latex stability for all coating samples employed in t~is test : - 10 was satisfactory. The remaining results,which includea a :: repeat of the ash pickup test at a lower relative humidity appear below in Table V.
TABLE V
Example Ratio ~Nitrate/ - ~OF
Number Terpolymer Ash Pickup At ~RH Static Klnetic 17 2.00 Poor31.5- C/C .30 .26 . , CJu .33 .~2 1~ 2.25 Poor . 31.5C/C .25 .27 ~ V .33 .~4 19 2.5~ Good 31.5CjC .27 .32 Poor 31.0C/U .35 .44
2.75 Good 31.5C~C .31 .37 Good 31.0~/U .33 1.2~
21 3.00 Good 31.5C/C .37 .~8 . Good 31.0C/U .30 .80 22 3.2S Good 31.5 C/C Blocked Blocked 2S Good 31.0 ~/U Blocked Blocked NOTE 1: Ash picXup was measured at a temper~ture of 76 F.
~OTE 2: C= ~ntistatic Coated Side .. .
U ~ ~ncoated Side At 31.0-31.5% relative humidity the ash pickup test results indicativc of the antistatic properties of t~e film,. ... . _.......
, -22- .
~5~175 indicated that acceptable results were obtained when the nitrate terpolymer ratio was between 2.75 and 3.25. At lower ratios unacceptable antista~ic properties were obtained.
Th~ slip properties of all the films formed in Examples 17-22 were acceptable overall, except for Example 22O This anomalous result cannot be explained except to indicate th~t it is at the upper end of the acceptable range.
- The test described in Examples 17-23 was repeated in accordance with the procedure of Example 4 with one small variation. That is, the test of Examples 17-23 was repeated for the case where the side opposite to the antistatic coated side is coated with the crosslinked acrylic coating described in Example 4 However, the coating concentration of the ~ weight crosslinkable acryl1c coating was 3.2% by~,based on the total weight o~ the coating latex composition.
- The films found in accordance with the Examples 24-29 were tested for the properties tested in Example 23.
In all examples acceptable haze values were obtained. In addition, the latex stability was rated good. As in Examples 17-23, ash pickup at 37~ relative humidity and 78 Q F was acceptable in all cases. However, at 31.0~ relative humidity, predictable results were obtained. These results are ~5 summarized in Table VI.
., , i .
- , . : . . ' . . ' ' . . . ' !
. . .. `
' TABLE VI
.: . . . . . .
Example Weight Ratio COF
Number Nitrate/Terpolymer Ash Pickup Statie Kinetie A/A .41 .43 - 24 2.00 Poor B/B .24 .28 A/B .~3 .38 A/A .41 .41 2.25 Poor E/B .27 .31 A/B .27 .33 A/A .45 47 . 26 2.50 Poor B/B . 29. 33 ; A/B .28 .46 A/A .43 .44 -27 2.7~ Good B/B .30 .38 A/B .30 .40 -- - O A~A .43 .48 28 3.00 Good B/B .~1 .46 - ~/B .26 .64 - , .
~/A .44 .48 29 3.25 Good B/B . 6 8. 7 8 . . A/B .32 .86 NOTE 1: Ash pickup was run at 31.0% relative humidity and O
76 F.
~OTE 2: In all eases the terpolymer eoncentration, in the antistatie latex employed in calculating the weight ratio was 1% by weight.
NOTE 3: A ~ Acrylie Coated Side B - Antistatie Coated Side The abQve results are in aeeordance wit~ those obtained in Example 23 inso~ar as the ash pickup anti$tatic character-isties are eoneerned. The slip properties o~ all the samples were aeeeptable ineluding the sample made in ~ccordance with - Example 29 at the weight ratio of 3.25, alth~u~h this film was deemed just barely acceptable.
.
~ . ~ . . 2~ ........ .. i ~5~7S
The above embodiments and examples illustrate the $cope : of the instant invention. Other embodiments and examples within the scope of the instant invention are wlthin the contemplation of this invention. Therefore, the scope of this invention should be limited only by the scope o~ the appended cla~ms.
',~' ' :
.
21 3.00 Good 31.5C/C .37 .~8 . Good 31.0C/U .30 .80 22 3.2S Good 31.5 C/C Blocked Blocked 2S Good 31.0 ~/U Blocked Blocked NOTE 1: Ash picXup was measured at a temper~ture of 76 F.
~OTE 2: C= ~ntistatic Coated Side .. .
U ~ ~ncoated Side At 31.0-31.5% relative humidity the ash pickup test results indicativc of the antistatic properties of t~e film,. ... . _.......
, -22- .
~5~175 indicated that acceptable results were obtained when the nitrate terpolymer ratio was between 2.75 and 3.25. At lower ratios unacceptable antista~ic properties were obtained.
Th~ slip properties of all the films formed in Examples 17-22 were acceptable overall, except for Example 22O This anomalous result cannot be explained except to indicate th~t it is at the upper end of the acceptable range.
- The test described in Examples 17-23 was repeated in accordance with the procedure of Example 4 with one small variation. That is, the test of Examples 17-23 was repeated for the case where the side opposite to the antistatic coated side is coated with the crosslinked acrylic coating described in Example 4 However, the coating concentration of the ~ weight crosslinkable acryl1c coating was 3.2% by~,based on the total weight o~ the coating latex composition.
- The films found in accordance with the Examples 24-29 were tested for the properties tested in Example 23.
In all examples acceptable haze values were obtained. In addition, the latex stability was rated good. As in Examples 17-23, ash pickup at 37~ relative humidity and 78 Q F was acceptable in all cases. However, at 31.0~ relative humidity, predictable results were obtained. These results are ~5 summarized in Table VI.
., , i .
- , . : . . ' . . ' ' . . . ' !
. . .. `
' TABLE VI
.: . . . . . .
Example Weight Ratio COF
Number Nitrate/Terpolymer Ash Pickup Statie Kinetie A/A .41 .43 - 24 2.00 Poor B/B .24 .28 A/B .~3 .38 A/A .41 .41 2.25 Poor E/B .27 .31 A/B .27 .33 A/A .45 47 . 26 2.50 Poor B/B . 29. 33 ; A/B .28 .46 A/A .43 .44 -27 2.7~ Good B/B .30 .38 A/B .30 .40 -- - O A~A .43 .48 28 3.00 Good B/B .~1 .46 - ~/B .26 .64 - , .
~/A .44 .48 29 3.25 Good B/B . 6 8. 7 8 . . A/B .32 .86 NOTE 1: Ash pickup was run at 31.0% relative humidity and O
76 F.
~OTE 2: In all eases the terpolymer eoncentration, in the antistatie latex employed in calculating the weight ratio was 1% by weight.
NOTE 3: A ~ Acrylie Coated Side B - Antistatie Coated Side The abQve results are in aeeordance wit~ those obtained in Example 23 inso~ar as the ash pickup anti$tatic character-isties are eoneerned. The slip properties o~ all the samples were aeeeptable ineluding the sample made in ~ccordance with - Example 29 at the weight ratio of 3.25, alth~u~h this film was deemed just barely acceptable.
.
~ . ~ . . 2~ ........ .. i ~5~7S
The above embodiments and examples illustrate the $cope : of the instant invention. Other embodiments and examples within the scope of the instant invention are wlthin the contemplation of this invention. Therefore, the scope of this invention should be limited only by the scope o~ the appended cla~ms.
',~' ' :
.
Claims (20)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A biaxially oriented polyester film comprising a polyester film support coated on one side with a latex coating, said coating including:
stearamidopropyldimethyl-.beta.-hydroxy-ethylammonium nitrate, present in a concentration in the range of between 2.75% and 3.25% by weight, based on the total weight of the latex coating;
a crosslinkable methylmethacrylate-ethyl acrylate-metha-crylamide terpolymer, having a glass transition temperature in the range of between about 40° C and 50° C, present in a concentration in the range of between about 0.75% and 1.25% by weight wherein the ratio of said stearamidopropyldimethyl-.beta.-hydroxy-ethyl-ammonium nitrate to said crosslinkable methylmethacrylate-ethyl acrylate-methacrylamide terpolymer is in the range of between about 2.75:1 and 3.25 1.
stearamidopropyldimethyl-.beta.-hydroxy-ethylammonium nitrate, present in a concentration in the range of between 2.75% and 3.25% by weight, based on the total weight of the latex coating;
a crosslinkable methylmethacrylate-ethyl acrylate-metha-crylamide terpolymer, having a glass transition temperature in the range of between about 40° C and 50° C, present in a concentration in the range of between about 0.75% and 1.25% by weight wherein the ratio of said stearamidopropyldimethyl-.beta.-hydroxy-ethyl-ammonium nitrate to said crosslinkable methylmethacrylate-ethyl acrylate-methacrylamide terpolymer is in the range of between about 2.75:1 and 3.25 1.
2. A biaxially oriented polyester film in accordance with claim 1 wherein the total dry coating weight of said coating on said polyester film is at least 0.003 pound per 1000 square feet of biaxially oriented film.
3. A polyester film in accordance with claim 2 wherein said total dry coating weight is in the range of between about 0.003 and 0.007 pound per 1000 square feet of biaxially stretched film.
4. A film in accordance with claim 1 wherein the weight ratio of said stearamidopropyldimethyl-.beta.-hydroxy-ethyl-ammonium nitrate to said crosslinkable methylmethacrylate-ethyl acrylate-methacrylamide terpolymer is in the range of between about 2.75:1 and 3.0:1.
5. A film in accordance with claim 1 wherein said polyester is polyethylene terephthalate.
6. A film in accordance with clalm 1 wherein said stearamidopropyldimethyl-.beta.-hydroxy-ethylammonium nitrate is present in said latex coating in a concentration in the range of between about 2.9% and 3.1% by weight, based on the total weight of said latex coating.
7. A film in accordance with claim 6 wherein said stearamido-propyldimethyl-.beta.-hydroxy-ethylammonium nitrate is present in said latex coating in a concentration in the range of between about 3.0% by weight, based on the total weight of said latex coating.
8. A film in accordance with claim 1 wherein said crosslinkable methylmethacrylate-ethyl acrylate-methacrylamide terpolymer is present in said latex coating in a concentration in the range of between about 0.9% and 1.1% by weight hased on the total weight of said latex coating.
9. A film in accordance with claim 8 wherein said crosslinkable methylmethacrylate-ethyl acrylate-methacrylamide terpolymer is present in said latex coating in a concentration in the range of about 1.0% by weight, based on the total weight of said latex coating.
10. A film in accordance with claim 1 wherein said cross-linkable methylmethacrylate-ethyacrylate-methacrylamide terpolymer has a glass transition temperature of between about 43° C and 47° C.
11. A film in accordance with claim 10 wherein said cross-linkable methylmethacrylate-ethylacrylate-methacrylamide temperature terpolymer has a glass transition/of 45° C.
12. A film in accordance with claim 1 wherein side opposite said latex coating is coated with a second latex coating, said second latex coating comprising a crosslinkable methyl-methacrylate-ethylacrylate-methacrylamide terpolymer having a glass transition temperature in the range of between about 40° C and 50° C, and present in a concentration of between about 3.0% and 4.0% by weight, based on the total weight of said second latex coating.
13. A process for forming an antistatic biaxially oriented polyester film comprising the steps of:
applying a latex coating, said coating comprising stearamidopropyldimethyl-.beta.-hydroxy-ethylammonium nitrate, present in a concentration in the range of between about 2.75% and 3.25% by weight, based on the total weight of said latex coating, a crosslinkable methylmethacrylate-ethyl acrylate-methacrylamide terpolymer having a glass transition temperature in the range of between about 40° C and 50° C
and present in a concentration in the range of between about 0.75% and 1.25% by weight based on the total weight of the latex coating wherein the weight ratio of said nitrate to said terpolymer is in the range of between about 2.75:1 and 3.25:1, to a uniaxially drawn polyester film;
heating said coated, uniaxially drawn film at a temperature in the range of between about 90° C and 110° C
wherein said coating is dried;
stretching said coated uniaxially drawn film in a direction normal to the direction of the uniaxially drawn film wherein biaxially drawn film is produced.
applying a latex coating, said coating comprising stearamidopropyldimethyl-.beta.-hydroxy-ethylammonium nitrate, present in a concentration in the range of between about 2.75% and 3.25% by weight, based on the total weight of said latex coating, a crosslinkable methylmethacrylate-ethyl acrylate-methacrylamide terpolymer having a glass transition temperature in the range of between about 40° C and 50° C
and present in a concentration in the range of between about 0.75% and 1.25% by weight based on the total weight of the latex coating wherein the weight ratio of said nitrate to said terpolymer is in the range of between about 2.75:1 and 3.25:1, to a uniaxially drawn polyester film;
heating said coated, uniaxially drawn film at a temperature in the range of between about 90° C and 110° C
wherein said coating is dried;
stretching said coated uniaxially drawn film in a direction normal to the direction of the uniaxially drawn film wherein biaxially drawn film is produced.
14. A process in accordance with claim 13 wherein said polyester is polyethylene terephthalate.
15. A process in accordance with claim 14 wherein said biaxially drawn film is heat set at a temperature in the range of between about 190° C and 240° C.
16. A process in accordance with claim 13 wherein said coating of said uniaxially drawn film is applied by roller coating.
17. A process in accordance with claim 16 wherein said uniaxially drawn film is applied by reverse gravure coating.
18. A process in accordance with claim 13 wherein said uniax-ially drawn film coated with said latex coating is longi-tudinally drawn film.
19. A process in accordance with claim 13 wherein said uniaxially drawn film is coated with a second coating on the side opposite said first coated side, said second coating comprising a latex coating including a crosslinkable methylmeth-acrylate-ethyl acrylate-methacrylamide terpolymer having a glass transition temperature in the range of between about 40° C and 50° C, present in a concentration in the range of between 3.0%
and 4.0% by weight, based on the total weight of said second latex coating.
and 4.0% by weight, based on the total weight of said second latex coating.
20. A process in accordance with claim 13 wherein said uniaxially drawn film is subjected to a corona discharge prior to the coating of said film.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US132879A | 1979-01-05 | 1979-01-05 | |
| US06/008,012 US4214035A (en) | 1979-01-31 | 1979-01-31 | Antistatic coated polyester film |
| US8,012 | 1979-01-31 | ||
| US1,328 | 1979-05-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1125975A true CA1125975A (en) | 1982-06-22 |
Family
ID=26668869
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA343,024A Expired CA1125975A (en) | 1979-01-05 | 1980-01-04 | Antistatic coated polyester film and process for forming same |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0013556B1 (en) |
| CA (1) | CA1125975A (en) |
| DE (1) | DE3070262D1 (en) |
| DK (1) | DK162534C (en) |
| NO (1) | NO157131C (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4486483A (en) * | 1983-07-11 | 1984-12-04 | American Hoechst Corporation | Polyester film primed with organic acid salts |
| DE8913676U1 (en) * | 1989-11-20 | 1990-01-25 | Hoechst Ag, 6230 Frankfurt | Coloured transparent wind sail made of polyester film |
| DE8913675U1 (en) * | 1989-11-20 | 1990-01-11 | Hoechst Ag, 6230 Frankfurt | Coloured transparent wind sail made of polyester film |
| US7867531B2 (en) | 2005-04-04 | 2011-01-11 | Curwood, Inc. | Myoglobin blooming agent containing shrink films, packages and methods for packaging |
| US8545950B2 (en) | 2004-04-02 | 2013-10-01 | Curwood, Inc. | Method for distributing a myoglobin-containing food product |
| US8053047B2 (en) | 2004-04-02 | 2011-11-08 | Curwood, Inc. | Packaging method that causes and maintains the preferred red color of fresh meat |
| US8029893B2 (en) | 2004-04-02 | 2011-10-04 | Curwood, Inc. | Myoglobin blooming agent, films, packages and methods for packaging |
| US8741402B2 (en) | 2004-04-02 | 2014-06-03 | Curwood, Inc. | Webs with synergists that promote or preserve the desirable color of meat |
| US8470417B2 (en) | 2004-04-02 | 2013-06-25 | Curwood, Inc. | Packaging inserts with myoglobin blooming agents, packages and methods for packaging |
| US8110259B2 (en) | 2004-04-02 | 2012-02-07 | Curwood, Inc. | Packaging articles, films and methods that promote or preserve the desirable color of meat |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL285238A (en) * | 1961-11-08 | |||
| US4089997A (en) * | 1974-05-14 | 1978-05-16 | Agfa-Gevaert N.V. | Process of applying antistatic coating compositions to polyester films |
| US3933516A (en) * | 1974-12-09 | 1976-01-20 | Gaf Corporation | Photographic element of improved antistatic and slippage properties containing calcium stearate dispersion and stearamido-propyl dimethyl-beta-hydroxy-ethyl ammonium nitrate; gelatinous composition, and method, for preparing said element |
| FR2381622A2 (en) * | 1977-02-23 | 1978-09-22 | Bat Applic Revetements Plastiq | Printable, semi-rigid, flat plastic article - consisting of thermoplastic sheet carrying ink absorbing layer contg. antistatic agent |
-
1980
- 1980-01-04 NO NO800021A patent/NO157131C/en unknown
- 1980-01-04 EP EP80100020A patent/EP0013556B1/en not_active Expired
- 1980-01-04 CA CA343,024A patent/CA1125975A/en not_active Expired
- 1980-01-04 DK DK004780A patent/DK162534C/en not_active IP Right Cessation
- 1980-01-04 DE DE8080100020T patent/DE3070262D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NO157131B (en) | 1987-10-19 |
| EP0013556A1 (en) | 1980-07-23 |
| DK162534C (en) | 1992-03-30 |
| DE3070262D1 (en) | 1985-04-18 |
| NO157131C (en) | 1988-01-27 |
| DK4780A (en) | 1980-07-06 |
| NO800021L (en) | 1980-07-07 |
| EP0013556B1 (en) | 1985-03-13 |
| DK162534B (en) | 1991-11-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |