JPS6261417B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a thickness of approximately 50 μm or less, an indeterminate length, and an edge elastically deformed along the length, and is suitable for winding up and during winding of the web. A web of thermoplastic film material having improved handling properties and improved roll quality and appearance of the web when wound. HEvan
Derhoef) U.S. Patent No. 6, December 1927
No. 1,651,744 describes intentionally creating a permanent bump-like deformation on the edge of a film web. The bumps provide a depth that permanently separates adjacent layers of rolled film material. It is stated that adjacent layers of the film do not touch each other anywhere on the roll. A typical degree of permanent film depth is 2 times the film web thickness.
It's twice as much. A.D.A. Spencer (AW)
Spencer), U.S. Patent No. 24, 1970,
No. 3,502,765 describes substantially the same edge welts as in the aforementioned patents, but it is further recognized that such welts often produce fluted or tipped webbing edges. . To prevent this additional secondary deformation, it has been stated that the edges of the web are heated to cause a small shrinkage just before use of the webbing wheel. The patent describes polyethylene terephthalate as a particularly suitable thermoplastic web material, but the increase in edge thickness due to the webbing is, for example, 50%. Although the film thickness range described is approximately 25-250 μm, the welts obtained by this method are permanent and are not intended to separate adjacent layers of the wound film web. be. FJPira et al. 1977 5
U.S. Pat. No. 4,021,179, dated May 3, describes the application of welts to the edges of thermoplastic material (especially polyethylene terephthalate) webs. It gives a deeper depth compared to the depth of the tsubutsubu using a car. This patent generally describes a method for embossing films with a thickness of 150 μm or more, in which deep permanent embossments are applied to separate adjacent layers of web in the form of a roll. Although deformation losses in adjacent layers of the burled film are taken into account, the main objective is that the depth must be maintained to permanently separate the layers and stabilize the roll. It is. This patent states that bulges that are not permanent and deep are unsuitable and undesirable. Thin web materials are difficult to wind into stable rolls. Rolls of such materials are telescoping (a phenomenon in which the inner layer extends outwards and pops out).
Also, ripples, bumps, and wrinkles occur in the radial direction around the roll. As mentioned above, stable rolls of thick web materials with a thickness of 150 mm or more have been made by deep webbing, but
A permanently thickened edge is thereby applied to the web material. However, such a textured thin web material is more susceptible to ridges and wrinkles than a roll made from the same thin material without the texture. The present invention relates to a method for treating the edges of thin web material so as to produce wound rolls with fewer ripples, ridges and wrinkles and a reduced tendency to telescoping during high speed winding. In accordance with the present invention, a web of thin thermoplastic film material of variable length is provided with a pattern of resilient deformations along its length. The web has a thickness of less than about 50 μm, greater than 1 μm, and generally greater than about 10 μm. A roll of web is also provided. The resilient deformations of the present invention are pressed into the web only to the extent that the deformations are flattened and substantially completely eliminated by the forces of adjacent film layers when the web is wound into a roll. In FIG. 1, a web 10 of indefinite length is shown.
is wound around the core 12 of the roll to form a wound roll 11, and each winding of the roll creates a layer of the wound web. At least one edge of the web 10 is provided with a continuous pattern 13 with elastic deformations parallel thereto. In the wound roll 11, patterns 13 of deformations from adjacent film layers are superimposed. The film material of the present invention is thin, as described above, and has properties such that the structure of the material undergoes elastic deformation without permanent lateral movement. The film is generally a thermoplastic organic polymeric material and generally has a thickness of 1 to 50 μm. However, the thickness of the film is most often at least 10 μm. Although the present invention may be practiced with a variety of film materials including polyolefins, polyimides, with or without halogenation, and polyesters with or without coatings with other materials in general, it has been found to be particularly useful for films of polyethylene terephthalate. Served. Until now, it has been extremely difficult to wind polyethylene terephthalate film webs with a thickness of about 50 μm or less at high speed into stable rolls with good appearance. The elastically deformed thin polyethylene terephthalate web material of the present invention has smooth edges and can be wound into rolls at up to twice the winding speed than can be used for such web materials without edge treatments. . During high-speed winding, air is trapped between the thin layers of web material, but the elastic deformation along the edges of the web allows the trapped air to escape for a reasonable amount of time. Adjacent web layers are slightly spaced apart. On the other hand, a web material with smooth edges will become a roll with so-called "sliding ripples" due to the trapped air.
Air cannot escape through the edges of the smooth film webs that are sealed together. Slip ripples have the appearance of blisters under the surface layer of a wound roll. The individual sliding ripples typically have an initial diameter of about 2-4 mm and a final diameter of 10-15 mm at the surface of the finishing roll. The web material of the present invention can be wound at high speeds into rolls with smooth, wrinkle-free surfaces and without the risk of telescoping. The elastic deformations are believed to act as springs with low tension, each of which actively but gently holds the edge of one web against the edges of adjacent upper and lower webs in the roll. ing.
The tighter the roll is rolled, the more the deformities or teeth are removed or flattened until it is substantially completely flattened and the web material contacts the adjacent upper and lower layers throughout the width of the roll. but,
Smooth-edged web materials rolled at low speeds to avoid slippage ripples are prone to telescoping at slightly lower winding tensions, or mechanical failure at slightly higher winding tensions. cause a bump in the direction. As previously mentioned, in the web material of the present invention, a number of gently resilient pressure points each exert a small radial force on the roll, thereby maintaining a slight lateral tension in the wound web. Telescoping is avoided. The web materials of the present invention can be coated and unrolled more quickly than web materials with smooth edges and fewer obstacles between adjacent layers. Furthermore, when the web material of the present invention is coated from edge to edge, there is less waste than when the web material is coated with knotted edges that cannot be covered. The reason for the above-mentioned bulge in the machine direction is that
not fully understood. Machine direction bumps often occur in rolls where thin web material is wound after the roll is made. For example, machine direction bumps tend to occur on the outer surface of thin polyethylene terephthalate, when the film web has smooth edges, after about 1 to 5 days, usually two days, after being rolled. Since it is not known why a roll of smooth edged film would have a ridge in the machine direction, it is also not known why a roll of the web material of the present invention would not have such a ridge. However, it is certain that the smooth rolls of thin polyethylene terephthalate of the present invention will not later develop bumps in the machine direction. The elastic deformation of the thin web of the present invention is very different from the welts applied to the edges of the web to separate adjacent layers of web material. The welts attached to some of the conventional methods mentioned above are permanent deformations of the film web;
Generally involves some movement of material. Wetting intentionally and in practice creates a permanent thickness of material over the webbing area and substantially increases the thickness of the material at least at the edges of adjacent webbing layers in the roll. And permanent separation occurs. The buffing force applied to a film web having a thickness of only about 1 to about 50 μm causes permanent deformation, resulting in a roll of web material with hard edges in the blobed area;
Severe lateral wrinkling occurs in the unsupported film material across the roll at the center of the roll between the bumpy areas. An advantage of the present invention in this regard is that the width-to-thickness ratio of the web is at least
Occurs at 10 ⁴ . As previously mentioned, the elastically deformed portion of the web of the present invention is substantially flattened by the cumulative forces created when successive layers of the web are rolled over previously rolled layers. completely removed. Because it is elastic, the deformation will return when the web is rolled back. Of course, the reverted deformation is just as useful in re-rolling the web material as it was in the initial winding. Figures 2a and 2b are schematic illustrations of the film web of the present invention. In FIG. 2a, one edge of the web 10 is shown in cross-section through a pattern of elastic deformations 13. In FIG. The web 10 is not in contact with other web layers, and elastically deformed portions 13 are present throughout.
In FIG. 2b, the edge of one of several adjacent layers of the web 10 is shown in cross-section as rolled up. The elastic deformations 13 are progressively flattened through the adjacent layers of the roll from the outer layer 10' to the inner layer 10''. Adjacent deformations usually do not coincide with each other, and in this case as well. The elastic deformation can be substantially completely collapsed after several layers have been rolled, or it can remain after several layers have been rolled. The sections can be present in a pattern of at least one row and up to six or more rows. The deformation can take the form of teeth or grooves or other equivalent discontinuities of small sections. In FIG. is a web 1 of the present invention with elastic deformation 14
A cutaway cross-sectional view of the surface of a portion of 0 is shown.
The deformations 14 are pressed into the web 10 in any pattern of spaced rows, but can also take any shape. Preferably, the deformation or tooth pattern is made such that the distance between the teeth is approximately 0.5 to 10 mm. The lower limit of spacing is not believed to be critical, but the upper limit is chosen to maintain a sufficient number of pressure points to obtain the desired properties of the web during winding and when formed into a roll. FIG. 4 is a cutaway view of the surface of a portion of the web 10 of the present invention having an elastically deformed portion 16. The deformations 16 can be pressed into the web 10 as a pattern of parallel grooves, as specifically shown in FIG. 4, or can be present as a twisted pattern along the edges of the web. The grooves can be considered to be elongated grooves, and if they do not intersect, it is preferred that adjacent grooves are no more than 6 mm apart. Where high speed winding is important, it is preferred that any pattern of grooves provide a path across the pattern without deformations to allow air trapped during the winding operation to escape. The elastic deformation can be applied to the thin web of thermoplastic material by any method that produces plastic deformation without substantially lateral movement of the material. For example, the aforementioned U.S. Patent No. 4021179
The carving wheels described in the above patent may also be used as long as the deformation forces are sufficiently lower than those that would cause permanent deformation and lateral movement of the film material. When using a car for attaching bumps,
Used on a smooth resilient roll, the web material drawn between the wheel and the resilient roll is pressed into a roll, and the webbing wheel is pressed onto a hard roll or a mated roll. It is possible to provide mere teeth that are not permanently deformed by lateral movement of the web material as would occur when used on a webbing wheel. The web of the present invention is made by drawing a thin, smooth-edged web through a pair of wheels or rollers. This wheel or roll consists of one member having feet for pressing the edge of the web and another member having a smooth, resilient surface which is subject to the pressure of the footed member. The spacing of the rollers must be carefully selected to maintain the desired light force in the deformation section. The particular preferred deformation force will vary depending on various conditions and the thickness and type of film, but the footed wheel is made to be in contact with the film for a given period of time with a total area of about 3 to 19 ^mm2 . Approximately 4
Contact with a force of ~35 Newtons, approximately 1200~7300KPa
deformation pressure must be applied.
Shore "A" hardness as determined by the durometer scale of 75 to 95, or Shore "D"
Hardness determined by hardness durometer scale
45 to 55 wheels of elastomeric material, such as rubber or polyurethane, are applied with the above forces and pressures across the film. The elastic deformation of the present invention is such a small deformation that it is difficult to measure. In fact, if the lighting conditions aren't right, the deformed part may not even be visible. The degree of deformation is not readily described or measured, but can be easily determined by a simple web roll test. As described above, the thin film web is drawn between the rollers, with the deformation force being adjusted within the range mentioned above, i.e., less than the force expected by experiments commonly used to apply webs to plastic films. Adjust to low force, then roll and evaluate. Since different materials and thicknesses require different pressures to achieve the elastic deformation of the present invention, this value is determined by a simple rolling experiment. BEST MODE AND INDUSTRIAL APPLICATION To illustrate the invention using polyethylene terephthalate, the edges of a web 12 μm thick and approximately 2 1/2 m wide are passed through a pair of rollers, one on each edge. Pressed elastic deformation. One of the rollers on each edge is 3cm in diameter and 2.5cm wide
The legs have an area of approximately 0.75 mm ² and are spaced 2 mm apart in the axial direction and 2 mm apart in the radial direction. Each footed roller has two axial rows of feet, which are 10cm in diameter and 250cm wide.
The hardness determined by the shore "A" durometer scale is pressed against a 90 smooth polyurethane roller. The rollers are adjusted so that a total pressure of about 1250KPa is applied to the film placed between the legs. When this pressure is applied to a thin polyethylene terephthalate film under the conditions described above, it produces a web of the invention with elastic deformation, resulting in a stable, wrinkle-free roll when wound at speeds of 8 m/s or more. arise. As a control test, when the same film without elastic deformation is rolled up at only a maximum of 6 m/s, severe machine direction bumps appear on the surface of the roll after two days. If this film is rewound at a speed greater than 6 m/sec, there is a tendency for telescoping during winding. As another control test, a knurling wheel of the same design as the one above was used, but with four rows of teeth in the axial direction, and a knurling force of approximately 125 Newtons (corresponding to a knurling pressure of approximately 13,500 KPa) was used. If the same film with edges applied is wound at a speed greater than 6 m/s, the roll will have a very hard edge and a loose, heavily wrinkled center, and the web will move from edge to edge, causing unsightly damage. Produces a roll with uniform edges. Polyethylene terephthalate films of various thicknesses of the present invention were made using the same elastic rollers and rollers with feet as described above, and at the pressures shown in the table below. It has been found that the preferred pressures described above provide films exhibiting the most desirable properties under the conditions described herein. The highest values represent lower pressures where the film product now exhibits the appearance and handling characteristics for a film with brushed edges. Although the benefits of elastic deformation of the present invention can be realized with any degree of such deformation, the above minimum values represent a practical lower limit of pressure useful for obtaining the deformations described herein. shows. 【table】

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the web of the present invention wound into a roll, FIG. 2a is a cross-sectional view showing the web of the present invention in which no force is applied to adjacent film layers, and FIG. FIG. 3 is a cutaway view showing a part of the web of the present invention, and FIG. 4 is a cross-sectional view of a film layer obtained by rolling up the web of the present invention in several layers. It is a cutaway diagram. All figures are not to scale and have been enlarged to better visualize the size of the elastic deformation.

Claims (1)

[Scope of Claims] 1. Heat of variable length, about 1 to 50 μm thick, with a continuous pattern of elastic deformations parallel to the length and along at least one edge. A web of plastic film material, wherein the resilient deformations are pressed into the web only to the extent that they are substantially completely removed by the forces of adjacent film layers when the web is wound into a roll. Wetsubu is characterized by certain things. 2. The web according to claim 1, wherein the thermoplastic material is polyethylene terephthalate. 3. The web according to claim 1, wherein the thickness of the film material is about 10 μm or more. 4. The web according to claim 1, wherein the pattern of elastic deformation is provided in 1 to 6 rows. 5 The pattern of elastic deformation is in the form of 1 to 6 rows of teeth, with teeth approximately 0.5 to
The web according to claim 1, which is spaced apart by 10 mm. 6. A method for pressing an elastic deformation part on the edge of a web of thermoplastic film material having a thickness of about 1 to 50 μm and an indefinite length, a member having legs for pressing the web; The edge of the web is drawn between a pair of rollers consisting of another member having a smooth and resilient surface that is subjected to the pressure of the footed member, and the web drawn therebetween undergoes plastic deformation. A method characterized in that the rollers are spaced so as to receive web deformation forces that are less than required for permanent deformation with lateral movement of the thermoplastic material. 7. A patent for winding the web onto a roll after retraction, on which the elastic deformation is rolled over successively adjacent film layers and is substantially completely removed by the force of the adjacent film layers. The method according to claim 6.