{United States Patent
`
`[191
`
`,
`
`1111
`
`3,899,452
`
`Koch et a1.
`[45] Aug. 12, 1975
`
`
`[541 CELLULOSIC FILM HAVING INCREASED
`
`[75]
`
`STIFFNESS
`Inventors Walter T- Koch, Havenown;
`Edward A. WieliCRi, Philadelphia,
`both of Pa.
`
`2,885,303
`3,099,637
`3,228,897
`3,353,981
`3,365,358
`3,615,972
`
`5/1959 Kaplan...., ........................ 260/25 B
`7/1963 Neillesen....
`106/193 J
`1/1966 Neillesen....
`106/193 J
`11/1967
`Jacob ......
`260/25 13
`1 / 1968 Huchins ........................... 260/25 B
`10/1971 Morehouse, Jr. et aI. ....... 260/25 B
`
`
`
`[73] Assignee: FMC Corporation, Philadelphia, Pa.
`[22] Filed:
`Oct. 8, 1971
`‘
`[21] Appl. No.: 187,918
`
`Primary Examiner—Morton Foelak
`
`[52] US. Cl. ............ 260/25 B; 106/189; 260/17 R;
`260/ 17.4 R
`Int. Cl.2............................................. C08,] 9/32
`[51]
`[58] Field of Search ............. l61/DIG. 5; 106/196 J;
`260/25 B
`
`[57]
`
`.
`
`ABSTRACT
`
`A non-fibrous, self-supporting cellulosic film contain-
`ing a small proportion of rigid hollow microspheres to
`increase film stiffness, and a method of preparing the
`film are disclosed herein.
`
`[56]
`
`References Cited
`
`2,646,364
`
`UNITED STATES PATENTS
`7/1963
`Porth ............................... 106/193 J
`
`'
`
`7 Claims, No Drawings
`
`CLIO USA
`EXHIBIT 1007
`PAGE 000001
`
`PAGE 000001
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`CLIO USA
`
`EXHIBIT 1007
`
`

`

`1
`CELLULOSIC FILM HAVING INCREASED
`STIFFNES'S
`
`3,899,452
`
`2
`:: heated at" a suitably'high temperature to expand the
`spheres from about 2 to 5'times their original diame-
`ters.
`'
`
`For certain applications, for example, film used in
`push—feed machinery, it is desired to prepare and use
`regenerated cellulose films, cellulose ether films, cellu-
`lose ester films or other non-fibrous self—supporting cel-
`lulosic films, having increased stiffness. The stiffer film
`is also desirable for use in snack packages for display
`purposes and ease of stacking. Film rigidly conveys the
`idea of crispness in packaged goods. The stiffness of
`cellulosic film can be increased by decreasing the
`amount of plasticizer incorporated in the film or by in-
`creasing the thickness of the film. However, the lower-
`ing of the amount of plasticizer in the film generally de-
`grades film properties, such as durability, while increas—
`ing the thickness of the film is relatively expensive.
`It is an object of this invention to provide a non-
`fibrous cellulosic film having increased stiffness with-
`out an increase of cellulose content or a decrease in
`plasticizer content of the film.
`It is another object of this invention to provide a re-
`generated cellulose film having improved stiffness and
`durability.
`These and other objects are attained in accordance
`with this invention which comprises a non—fibrous, self-
`supporting cellulosic film having dispersed therein
`from about 1 up to about 25 percent, based on the
`weight of the cellulosic, of rigid hollow microspheres
`having a bulk density in the range of 0.2 to 20 pounds
`per cubic foot and diameters ranging from 1 to 100 mi-
`crons.
`
`The cellulosic films for this invention are regenerated
`cellulose films and cellulose derivative films including,
`for example, cellulose ester films, preferably cellulose
`nitrate and cellulose acetate films; cellulose ether films,
`preferably hydroxyethyl cellulose ether and hydroxy-
`propyl cellulose ether films; and other cellulose deriva-
`tive films well known in this art. The preferred cellu—
`losic film are regenerate cellulose films prepared by the
`viscose method since these are in commercial use in the
`largest amount.
`Film weights per square meter including the weight
`of the dispersed hollow microspheres are generally up
`to about 100 grams.
`Conventional plasticizers for cellulosic films are used
`where necessary. Plasticizers for regenerated cellulose
`films, for example, glycerol and polyethylene glycols,
`are used in conventional amounts preferably ranging
`from about 15 to about 30%, based on the weight of the
`cellulose.
`-
`
`The rigid hollow microspheres useful for this inven-
`tion include those prepared from a variety of materials
`including polycondensation resins of both the thermo—
`plastic and thermosetting type, addition polymerization
`resins, and glass. The chemical nature of the rigid mi-
`crospheres is not critical in order to produce stiffer
`films although the physical properties such as size and
`bulk density are critical.
`The methods for preparing these rigid hollow micro-
`spheres are well known for any particular material em-
`ployed. One very practical method is set forth in Bel-
`gian Pat. No. 641,711 wherein tiny microspheres are
`prepared by the limited coalescence polymerization
`technique utilizing a polymerizable monomer and a
`volatile blowing agent which exhibits limited solubility
`in the polymer. After drying,
`the microspheres are
`
`Many suitable blowing or expanding agents are avail-
`able for use in the process of forming expandable ther-
`moplastic microspheres. Some of these are pentanes,
`butanes, and halohydrocarbonsf ‘
`Examples of monomer and comonomer polymeriz-
`able systems from which the microspheres can be pre-
`pared include methyl methacrylate,
`8 parts (wt.)
`methyl methacrylate and 2 parts (wt.) styrene, 9 parts
`methyl methacrylate and 1 part ethyl methacrylate, 7
`parts methyl methacrylate and 3 parts ethyl methacryl-
`ate, 5 parts methyl methacrylate and 5 parts ethyl
`methacrylate, 9 parts ethyl methacrylate and 1 part
`methyl methacrylate, 9 parts methyl methacrylate and
`1 part orthochloro styrene, orthochlorostyrene, vinyl-
`benzyl chloride, 7 parts acrylonitrile and 3 parts vinyli-
`dene Chloride, 5 parts acrylonitrile and 5 parts vinyl
`chloride, 9 parts methyl methacrylate and 1 part acry-
`lonitrile, 7 parts methyl methacrylate and 3 parts of
`para—t—butyl styrene, 8 parts methyl methacrylate and
`2 parts vinyl acetate. 9.8 parts styrene and 0.2 parts
`methacrylic acid; 8.3 parts styrene, 0.2 parts meth-
`acrylic acid and 15 parts vinylbenzyl chloride, 9.1 parts
`vinylidene chloride and 0.9 part acrylonitrile and the
`like. While the particular resin used is not critical, the
`preferred synthetic thermoplastic hollow spheres are
`those prepared from vinylidene chloride and acryloni—
`trile because of their availability and higher compatibil-
`ity with cellulosics.
`The term “hollow” as used herein relative to the mi-
`crospheres is only meant to designate an internal area
`of the microspheres which is free of solid material. This
`area will contain a fluid, for example, air, blowing agent
`or other gas.
`The rigid hollow microspheres which are useful fer
`this invention, in general, have a bulk density ranging
`from about 0.2 to about 20 pounds, preferably 0.5 — 5.0
`pounds per cubic foot and a diameter ranging from
`about 1 to 100 microns. lt is often helpful to classify the
`microspheres into narrower diameter ranges within the
`broad given range so that they may be more advanta-
`geously employed in the manufacture of films of differ—
`ent thicknesses. For example, if one desires to produce
`a film of a thickness of about 1 mil, microspheres hav-
`ing diameters of less than 30 microns and averaging
`about 20 microns can be effectively employed to pro-
`duce a film with minimal surface irregularities. On the
`other hand, if one wishes to produce a film having a
`bumpy surface, microspheres which are larger in diam-
`eter than the ordinary thickness of the film can be used.
`While the microspheres can be incorporated in the
`cellulosic film in amounts ranging from 1 to 25%, based
`on the weight of the cellulosic, from about 3 to about
`10% is the preferred range.
`Conventional coatings for cellulosic films may be ap-
`plied to the films of this invention from lacquer or latex
`compositions. For example, nitrocellulose coatings,
`vinyl coatings, olefin coatings and saran coatings are
`useful.
`
`The cellulosic films having the rigid hollow micro-
`spheres dispersed therein are prepared by forming cel-
`lulosic solutions, mixing the microspheres in the solu-
`tion, extruding the solution in the form of a film into a
`coagulating medium and recovering the film. Obvi-
`
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`PAGE 000002
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`PAGE 000002
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`3
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`3,899,452
`
`4
`
`ously, cellulosic solutions which could dissolve the mi-
`crospheres should be avoided.
`In the case of regenerated cellulose film prepared by
`the viscose method any film-forming viscose solution
`can be used. The microspheres are compatible with vis-
`cOse and are readily mixed therewith by first making a
`“paste” of the microspheres with water and then intro-
`
`closed jar permitted testing of the film samples at con-
`trolled moisture content and temperature.
`The following table shows the relationship between
`microsphere content of the film, cellulose gram weight
`of the film, film stiffness and film durability for regener-
`ated cellulose (viscose) films cast from the same size
`film extrusion die.
`
`Table
`_________________—___———-——-—-—
`
`Total Hand
`Cellulose
`Durability,sec.
`Microsphere Content,
`not normalized
`45% R.H.,O°C.
`gram wt.,g/m.'-’
`g./100 g. of cellulose
`—___—_____—_—__————-——
`13.5
`87
`80
`11.8
`14,9
`—
`11.1
`18.3
`104
`10.2
`21.5
`107
`_____________.____————————
`
`wweobNU-I
`
`It is seen from the above table that the stiffness char-
`acteristics of the film increase distinctly as the amount
`of rigid microspheres in the film is increased. This is ac-
`complished without increasing the cellulose content of
`the film or decreasing its plasticizer content. In addi—
`tion, durability of the cellulose film is also increased.
`Various changes and modifications may be made in
`practicing the invention without departing from the
`spirit and scope thereof and, therefore, the invention is
`not to be limited except as defined in the appended
`claims.
`We claim:
`1. A non-fibrous, self-supporting cellulosic film hav—
`ing dispersed therein from about one up to about 25
`percent, based on the weight of the cellulosic, of rigid
`hollow microspheres having a bulk density in the range
`of 0.2 to 20 pounds per cubic foot and diameters rang-
`ing from one and 100 microns.
`2. The film of claim 1 wherein the amount of micro—
`spheres present in the film ranges from about 3 to
`about 10 percent, based on the weight of the cellulosic
`and the bulk density of the microspheres ranges from
`0.5 to 5 pounds per cubic foot.
`3. The film of claim 1 wherein the cellulosic is regen-
`erated cellulose.
`4. The film of claim 1 wherein the cellulosic is a cel-
`lulose ether.
`5. The film of claim 1 wherein the cellulosic is a cel-
`lulose ester.
`6. The film of claim 1 wherein the rigid microspheres
`are produced from a vinylidene chloride-acrylonitrile
`copolymer.
`7. The film of claim 1 wherein the cellulosic is regen-
`erated cellulose, the rigid microspheres are produced
`from vinylidene chloride—acrylonitrile copolymer, the
`microspheres are present in an amount ranging from
`about 3 to about 10 percent, based on the weight of the
`cellulose, and the bulk density of the microspheres
`*
`*
`*
`*
`*
`ranges from 0.5 to 5.0 pounds per cubic foot.
`
`ducing this into the viscose with stirring.
`The following example is set forth to demonstrate
`this invention.
`
`20
`
`EXAMPLE
`
`Expandable microspheres of vinylidene chloride-
`acrylonitrile copolymer resin containing a blowing
`agent were expanded by heating in water at 85°C. The
`microspheres were filtered off and dried at room tem-
`perature. The expanded microspheres had a bulk den-
`sity of about
`1 pound per cubic foot and diameters
`ranging from about 6 to about 66 microns and an aver-
`age diameter of about 33 microns.
`The microspheres were mixed with water to obtain a
`paste and the paste was added to a conventional film-
`forming viscose solution. Films of the viscose were then
`cast, coagulated and regenerated in an aqueous acid
`bath in the usual manner. The wet film was plasticized
`by passing it through an aqueous bath containing 6—8
`wt. % polyethylene glycol (avg. molecular weight of
`400) and then dried.
`Film stiffness was measured on the Thwing Albert
`Handle-O-Meter, a measuring device used in the textile
`and paper industries for this purpose. The slot width of
`the Handle-O-Meter was 5 millimeters and the sample
`size was 4 inches by 4 inches. Each sample was condi-
`tioned at 75°F. and 45% relative humidity. The results
`were expressed at “total hand” which was the sum of
`the four readings taken on both sides and in both .direc—
`tions of the samples. The higher the result, the stiffer _
`the film sample.
`Durability of the film samples was measured by form-
`ing bags of the film and inserting a specified weight of
`lead shot into the bag. The bag was closed and placed
`in a jar containing a baffle. The jar was closed and
`placed on its side between a set of revolving mill rolls.
`The bag in the jar was repeatedly lifted by the baffle
`and dropped as the jar rotated. The durability was mea-
`sured as the time period (in seconds) from the start of
`rotation of the jar to the time of rupture of the bag. The
`
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`PAGE 000003
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`PAGE 000003
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`
`
`UNITED STATES PATENT OFFICE
`CERTIFICATE OF CORRECTION
`
`2
`:
`
`:‘
`
`3,899,452>
`August 12,1975
`Walter T. Koch and Edward A. Wielicki
`
`PATENT NO.
`DATED
`
`INVENTOR(S)
`
` [SEAL]
`
`It is certified that error appears in the abbve—identi
`are hereby corrected as shown below:
`Column 2,
`line 19, ”vinyl” should read —-vinylidene——.
`
`fied patent and that said Letters Patent
`
`Signed and Sealed this
`
`twenty—fifth Day of November 1975
`
`Attest:
`
`:tli'flfp. MASON
`e: mg Officer
`
`‘
`
`C. MARSHALL DANN
`Commissioner ufParenrs and Trademarks
`
`L-..
`
`_“______-..____———————’——’4—"—
`
`PAGE 000004
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`PAGE 000004
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