US4978484A — Method of and apparatus for manufacturing biaxial…

Claim 1

Independent Claim 180 words

In a method of manufacturing a biaxially oriented film, including the steps of rapidly cooling molten thermoplastic resin, which has been extruded from an annular extruding die, to form a tubular original film, biaxially orienting said tubular original film by heat supplied from a heating means while conveying said tubular original film between two sets of nip rolls, each nip roll having an individual circumferential speed, and forming said tubular original film, during said conveyance thereof between said nip rolls, into a shape of a bubble by injecting pressurized gas into said tubular original film, the improvement comprising the steps of: detecting a thickness distribution of at least one of said original film and said biaxially oriented film; detecting a temperature distribution around at least one of said annular extruding die and said heating means, which temperature distribution corresponds to said thickness distribution; changing said temperature distribution based on a relationship between said thickness distribution and said temperature distribution, whereby said thickness distribution of said at least one of said original film and said biaxially oriented film is made uniform.

Claim 2

Dependent Claim 180 words

In a method of manufacturing a biaxially oriented film, including the steps of rapidly cooling molten thermoplastic resin, which has been extruded from an annular extruding die, to form a tubular original film, biaxially orienting said tubular original film by heat supplied from a heating means while conveying said tubular original film between two sets of nip rolls, each nip roll having an individual circumferential speed, and forming said tubular original film, during said conveyance thereof between said nip rolls, into a shape of a bubble by injecting pressurized gas into said tubular original film, the improvement comprising the steps of: detecting a thickness distribution of at least one of said original film and said biaxially oriented film; detecting a temperature distribution around at least one of said annular extruding die and said heating means, which temperature distribution corresponds to said thickness distribution; changing said temperature distribution based on a relationship between said thickness distribution and said temperature distribution, whereby said thickness distribution of said at least one of said original film and said biaxially oriented film is made uniform.

Claim 3

Dependent Claim 25 words

The method of manufacturing a biaxially oriented film according to claim 1, wherein said step of changing said temperature distribution includes division-controlling said temperature distribution.

Claim 4

Dependent Claim 91 words

The method of manufacturing a biaxially oriented film according to claim 2, wherein said division-controlling step includes calculating desired heating conditions for division-controlling said temperature distribution around said at least one of said extruding die and said heating means from said measured thickness distribution by using a predetermined formula which compares a desired thickness accuracy of said biaxially oriented film to a thickness accuracy of said biaxially oriented film with said heating conditions arranged to be constant, and performing said division control of said temperature distribution automatically based on said calculation.

Claim 5

Dependent Claim 61 words

The method of manufacturing a biaxially oriented film according to claim 1, wherein said biaxially orienting step includes spraying air to a point on an exterior surface of said original film, and an angle defined between a direction in which said air is sprayed and a direction in which said film is convened is arranged to be 30 to 60 degrees.

Claim 6

Dependent Claim 201 words

In an apparatus for manufacturing a biaxially oriented film, including an annular extruding die and means for obtaining a tubular original film by extruding molten thermoplastic resin from said annular extruding die and thereafter rapidly cooling said resin, means for producing a biaxially oriented film from said tubular original film, including means for applying heat to and injecting pressurized gas into said tubular original film, and two sets of nip rolls for conveying said tubular original film therebetween and between which said heat is applied, the improvement comprising: means for enabling a temperature distribution around at least one of said extruding die and said biaxially oriented film to be division-controlled; means for detecting a thickness distribution of at least one of said original film and said biaxially oriented film, which thickness distribution corresponds to said temperature distribution; temperature distribution detecting means for detecting a value of said temperature distribution around said at least one of said extruding die and said biaxially oriented film; and control means for division-controlling said temperature distribution around said at least one of said extruding die and said biaxially oriented film based on a relationship between said detected thickness distribution and said corresponding detected temperature distribution value.

Claim 7

Dependent Claim 201 words

In an apparatus for manufacturing a biaxially oriented film, including an annular extruding die and means for obtaining a tubular original film by extruding molten thermoplastic resin from said annular extruding die and thereafter rapidly cooling said resin, means for producing a biaxially oriented film from said tubular original film, including means for applying heat to and injecting pressurized gas into said tubular original film, and two sets of nip rolls for conveying said tubular original film therebetween and between which said heat is applied, the improvement comprising: means for enabling a temperature distribution around at least one of said extruding die and said biaxially oriented film to be division-controlled; means for detecting a thickness distribution of at least one of said original film and said biaxially oriented film, which thickness distribution corresponds to said temperature distribution; temperature distribution detecting means for detecting a value of said temperature distribution around said at least one of said extruding die and said biaxially oriented film; and control means for division-controlling said temperature distribution around said at least one of said extruding die and said biaxially oriented film based on a relationship between said detected thickness distribution and said corresponding detected temperature distribution value.

Claim 8

Dependent Claim 84 words

The apparatus for manufacturing a biaxially oriented film according to claim 5, wherein said control means includes: computing means for computing a proper temperature distribution around said at least one of said extruding die and said biaxially oriented film based on said detected temperature distribution value and said corresponding detected thickness distribution; and a temperature adjustment control device capable of division-controlling said temperature distribution around said at least one of said extruding die said biaxially oriented film based on the thus-computed proper temperature distribution.

Claim 9

Dependent Claim 44 words

The apparatus for manufacturing a biaxially oriented film according to claim 5, wherein said control means further includes means for storing data on said thickness distribution of said original film and means for storing data on said thickness distribution of said biaxially oriented film.

Claim 10

Dependent Claim 78 words

The apparatus for manufacturing a biaxially oriented film according to claim 5 wherein said means for producing said biaxially oriented film includes an air ring capable of spraying air to a point on an exterior surface of said original film and arranged in such a manner that an angle formed by a direction in which said air is sprayed and a direction in which said biaxially oriented film is conveyed is arranged to be 30 to 60 degrees.

Claim 11

Dependent Claim 150 words

In a method of manufacturing a biaxially oriented film, including the steps of rapidly cooling molten thermoplastic resin, which has been extruded from an annular extruding die, to form a tubular original film, biaxially orienting said tubular original film by applying heat thereto between two spaced sets of nip rolls and by injecting pressurized gas thereinto, the improvement comprising: moving one of said sets of nip rolls to elongate a distance between said two sets of nip rolls in response to a detection that said biaxially oriented film has an actual width which is larger than a desired width; and moving one of said sets of nip rolls to shorten the distance between said two sets of nip rolls in response to a detection that said actual width of said biaxially oriented film is smaller than said desired width, whereby an outer diameter of said biaxially oriented film is changed.

Claim 12

Dependent Claim 150 words

In a method of manufacturing a biaxially oriented film, including the steps of rapidly cooling molten thermoplastic resin, which has been extruded from an annular extruding die, to form a tubular original film, biaxially orienting said tubular original film by applying heat thereto between two spaced sets of nip rolls and by injecting pressurized gas thereinto, the improvement comprising: moving one of said sets of nip rolls to elongate a distance between said two sets of nip rolls in response to a detection that said biaxially oriented film has an actual width which is larger than a desired width; and moving one of said sets of nip rolls to shorten the distance between said two sets of nip rolls in response to a detection that said actual width of said biaxially oriented film is smaller than said desired width, whereby an outer diameter of said biaxially oriented film is changed.

Claim 13

Dependent Claim 42 words

The method of manufacturing a biaxially oriented film according to claim 9, wherein said steps of adjusting the distance between said two sets of nip rolls are automatically controlled based on said detection of the actual width of said biaxially oriented film.

Claim 14

Dependent Claim 128 words

In an apparatus for manufacturing a biaxially oriented film, including an annular extruding die and means for obtaining a tubular original film by extruding molten thermoplastic resin from said annular extruding die and thereafter rapidly cooling said resin, means for producing a biaxially oriented film from said tubular original film, including means for applying heat to and injecting pressurized gas into said tubular original film, and two sets of nip rolls for conveying said tubular original film therebetween and between which said heat is applied, the improvement comprising: film width detecting means for detecting a width of said biaxially oriented film; and moving means for adjusting a distance between said two sets of nip rolls based on the film width detection performed by said film width detecting means.

Claim 15

Dependent Claim 128 words

In an apparatus for manufacturing a biaxially oriented film, including an annular extruding die and means for obtaining a tubular original film by extruding molten thermoplastic resin from said annular extruding die and thereafter rapidly cooling said resin, means for producing a biaxially oriented film from said tubular original film, including means for applying heat to and injecting pressurized gas into said tubular original film, and two sets of nip rolls for conveying said tubular original film therebetween and between which said heat is applied, the improvement comprising: film width detecting means for detecting a width of said biaxially oriented film; and moving means for adjusting a distance between said two sets of nip rolls based on the film width detection performed by said film width detecting means.

Claim 16

Dependent Claim 65 words

The apparatus for manufacturing a biaxially oriented film according to claim 11, wherein said moving means includes means for increasing the distance between said two sets of nip rolls if the detected width of said biaxially oriented film is larger than a desired width, and means for decreasing said distance if the detected width of said biaxially oriented film is smaller than said desired width.

Claim 17

Dependent Claim 31 words

The apparatus for manufacturing a biaxially oriented film according to claim 11, wherein said moving means includes means for permitting automatic control thereof based on the detection of said film width.

Claim 18

Dependent Claim 39 words

The apparatus for manufacturing a biaxially oriented film according to claim 11, wherein said moving means includes brackets for rotatably supporting one set of said nip rolls, and a feed screw mechanism for permitting raising and lowering said brackets.

Claim 19

Independent Claim 197 words

A method of manufacturing a biaxially oriented film, comprising the steps of: biaxially orienting a tubular original film obtained by rapidly cooling molten thermoplastic resin which has been extruded from an annular extruding die, including applying heat to said tubular original film between two sets of nip rolls and injecting pressurized gas into the inside thereof, and then folding said biaxially oriented film to form a flattened film; subjecting said flattened film to a first heat treatment at a first heat threatment temperature higher than a temperature at which said flattened film starts its contraction and lower by a predetermined degree than a melting point of said flattened film; cutting said flattened film and dividing said flattened film into two films; subjecting said two films to a second heat treatment at a second heat treatment temperature which is lower than said melting point of said two films and higher than a temperature which is lower by a predetermined temperature than said melting point, holding respective side ends of said two films laminated together with air interposed therebetween during said second heat treatment step; and winding said two films after said second heat treatment has been applied thereto.

Claim 20

Independent Claim 197 words

A method of manufacturing a biaxially oriented film, comprising the steps of: biaxially orienting a tubular original film obtained by rapidly cooling molten thermoplastic resin which has been extruded from an annular extruding die, including applying heat to said tubular original film between two sets of nip rolls and injecting pressurized gas into the inside thereof, and then folding said biaxially oriented film to form a flattened film; subjecting said flattened film to a first heat treatment at a first heat threatment temperature higher than a temperature at which said flattened film starts its contraction and lower by a predetermined degree than a melting point of said flattened film; cutting said flattened film and dividing said flattened film into two films; subjecting said two films to a second heat treatment at a second heat treatment temperature which is lower than said melting point of said two films and higher than a temperature which is lower by a predetermined temperature than said melting point, holding respective side ends of said two films laminated together with air interposed therebetween during said second heat treatment step; and winding said two films after said second heat treatment has been applied thereto.

Claim 21

Dependent Claim 44 words

The method of manufacturing a biaxially oriented film according to claim 15, wherein the first heat treatment temperature applied during said first heat treatment process is lower than a temperature which is lower than said melting point of said two films by 30° C.

Claim 22

Dependent Claim 55 words

The method of manufacturing a biaxially oriented film according to claim 16, wherein the second heat treatment temperature applied during said second heat treatment process is lower than said melting point of said two films and is higher than a temperature which is lower than said melting point of said two films by 30° C.

Claim 23

Independent Claim 187 words

An apparatus for manufacturing a biaxially oriented film comprising: an annular extruding die and means for obtaining a tubular original film by extruding molten thermoplastic resin from said annular extruding die and thereafter rapidly cooling said resin, means for producing a biaxially oriented film from said tubular original film, including means for applying heat to and injecting pressurized gas into said tubular original film, two sets of nip rolls for conveying said tubular original film therebetween and between which said heat is applied, means for folding said biaxially oriented film to form a flattened film; first heat treatment means for applying a first heat treatment to said flattened film; trimming means for cutting said flatted film to divide said flattened film into two films; means for laminating said two films with air interposed therebetween; means for holding respective ends of the two laminated films; second heat treatment means for applying a second heat treatment to said two films whose respective two ends are held; and means for winding said two films which have been subjected to said second heat treatment applied by said second heat treatment means.

Claim 24

Independent Claim 187 words

An apparatus for manufacturing a biaxially oriented film comprising: an annular extruding die and means for obtaining a tubular original film by extruding molten thermoplastic resin from said annular extruding die and thereafter rapidly cooling said resin, means for producing a biaxially oriented film from said tubular original film, including means for applying heat to and injecting pressurized gas into said tubular original film, two sets of nip rolls for conveying said tubular original film therebetween and between which said heat is applied, means for folding said biaxially oriented film to form a flattened film; first heat treatment means for applying a first heat treatment to said flattened film; trimming means for cutting said flatted film to divide said flattened film into two films; means for laminating said two films with air interposed therebetween; means for holding respective ends of the two laminated films; second heat treatment means for applying a second heat treatment to said two films whose respective two ends are held; and means for winding said two films which have been subjected to said second heat treatment applied by said second heat treatment means.

Claim 25

Dependent Claim 26 words

The apparatus for manufacturing a biaxially oriented film according to claim 18, wherein said first and second heat treatment means each comprises a hot air furnace.

Claim 26

Dependent Claim 36 words

The apparatus for manufacturing a biaxially oriented film according to claim 18, wherein said means for laminating said two films with air interposed therebetween includes a plurality of rolls each having means defining a groove therein.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-12-17	1994-06-18	1994-12-18	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-12-17	1998-06-18	1998-12-18	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-12-17	2002-06-18	2002-12-18	$7700.00	Window Closed / Lapsed

Method of and apparatus for manufacturing biaxially oriented film

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