JPH057302B2 - - Google Patents

Description

[Detailed description of the invention]

a. Field of Industrial Application The present invention relates to an improvement in a winding core used for winding up a sheet-like material such as a film (hereinafter referred to as a web) into a roll. b. Prior art and its problems Conventionally, sheet-like materials such as films, sheets, paper, woven fabrics, and processed products thereof are generally wound around cores such as metal tubes, plastic paper, or paper tubes. If the surface roughness of the sheet-like material (web) to be wound is low, if the air between the webs is sufficiently squeezed to stabilize the winding shape, the web near the core of the roll will have a core. Due to the influence of
A defective part appears for a considerable length with a loss of commercial value. For example, if the surface properties of the core are poor, the irregularities on the surface of the core will be directly transferred to the web surface, resulting in a rough surface like citrus skin or other defects on the web. To deal with this problem, a winding core is selected and used that has a sufficient surface finish to match the web to be wound. When the web starts to be wound around the core, there is a thickness error corresponding to the web thickness, which also causes transfer. This is sometimes called a splice mark. Further, when an adhesive tape is used to fix the winding start end of the web to the winding core, an error corresponding to the thickness of the adhesive tape occurs, and transfer due to this step also appears. These stepped portions are affected by the expansion and contraction of the core and/or web due to changes in temperature and humidity, and transfer continues from the inner layer to the outer layer of the roll, resulting in loss of several hundred meters in extreme cases. may occur. As a countermeasure to this problem, measures such as lowering the winding tension near the winding core and loosening the air squeeze are taken when winding the web, but this solution results in large winding misalignment, and the range of conditions that can be adopted is limited. is also limited. Furthermore, adhesive tapes are selected to be as thin as possible, but there are still limits to the solution of thinness alone. Attempts have been made to wrap a soft material such as rubber around the surface of the winding core in order to alleviate the adverse effects of the difference in thickness, but no results have been found that are overall satisfactory. In other words, in the case of rubber coating, a sheet of arbitrary thickness can be finished to a specified roughness by wrapping a thin rubber sheet around a hard core and then vulcanizing and finishing the surface. The problem is that it is limited to those with good heat resistance and is expensive. On the other hand, in the method of cutting a vulcanized thin rubber sheet and then winding it, the material of the hard core can be selected arbitrarily, but there is a problem in that it is difficult to obtain a sufficiently smooth surface especially with a thin sheet. Furthermore, when recycling cores, the rubber surface often has poor adhesive tape removability, making it difficult to correct and prevent reuse, resulting in increased costs. In either case, a rubber-coated winding core is extremely expensive and difficult to put into practical use if desired performance is to be achieved. c. Object of the Invention The present invention has been made in view of the above points, and an object of the present invention is to provide a winding core coated with a soft elastic material that can prevent the transfer of these stepped portions. In particular, the aim is to develop a highly practical winding core that has good surface finish, generates few scratches and dust during handling, and can be recycled, in addition to the ability to ease stepped portions. d. Structure of the Invention The above-mentioned winding core is obtained by coating the surface of a hard cylindrical core with a specific soft elastic material to an appropriate thickness. Here, the soft elastic material used for the coating must: (a) have a stress at 5% tensile elongation of 0.35 kg or more per 1 cm width as a covering material, and (b) be in a covered state (i.e., a state in which a winding core is formed). , the surface hardness is between 55 degrees and 90 degrees, and (c) it is an elastic sheet impregnated with and/or coated with an elastic resin while maintaining porosity in its fibrous porous structure. It is said that The elastic sheet of the present invention may be an artificial leather made of a well-known fibrous porous structure made of a nonwoven fabric, which is impregnated with and/or coated with an elastic resin such as a polyurethane resin, or an artificial leather made of a woven or knitted fabric made of a woven or knitted fabric made of the same structure, which is made of a nonwoven fabric with a well-known fibrous porous structure impregnated and/or coated with an elastic resin such as a polyurethane resin. Examples include synthetic leather. Note that these artificial leathers and synthetic leathers are preferably those that have not been subjected to surface finishing treatments such as colored patterns for decoration etc. as products. The soft elastic material used as the covering material of the present invention must have a stress of 0.35 kg or more per 1 cm of width at 5% elongation. ) There is a problem that interferes with the work of wrapping the covering material around the pipe. If the coating layer is too soft when forming the winding core, there is a risk that the core will be wound with tension, resulting in non-uniformity. In addition, if the beginning and end of the wrapping material overlap, a step will occur and the purpose cannot be achieved, and if a gap occurs, the gap should be 2 mm or less, preferably
It should be less than 0.5mm. because of these reasons,
To form a winding core, as mentioned above, a 5% elongation stress of 0.35 kg or more per 1 cm width is required. Therefore, there is no practical problem in increasing the thickness of a low modulus coating material. Note that the method for measuring 5% elongation stress will be described later. It is essential that the core of the present invention has a hardness in the range of 55 degrees to 90 degrees when covered with a soft elastic body. The present invention is a winding core for winding up a continuous web in which a coating film containing a magnetic material is provided on a plastic film such as polyester, and since splice marks etc. do not occur on the continuous web, the surface hardness of the winding core is above the above level. must satisfy the following range. For example, if the surface hardness is less than 55 degrees, there will be no splice marks, but when the web is wound into a roll, wrinkles are likely to occur at the beginning of the web, so there is a risk that the wrinkles may be transferred or propagated. In addition, for example, if the surface hardness exceeds 90 degrees, the core has almost no ability to absorb and disperse seaming force or external compression force.
Transfer of splice marks, etc. cannot be avoided. The surface hardness of the core coating layer is determined by a rubber hardness meter (JIS K6301-1975), and the measurement method will be described later. The winding core of the present invention has the function of the covering layer of the elastic sheet that satisfies the requirements (a), (b), and (c) described above. , scratches, etc.) (e) Dust generated from the winding core (surface and cut ends) (f) Dirt on the surface (especially when recycled, residual tape adhesive or tape peeling marks), etc. The risk of contamination is reduced. When the elastic sheet is an artificial leather or synthetic leather that has been surface-treated to have an appropriate surface quality that satisfies the above requirements,
Problems (d) to (f) have been virtually resolved. The winding core of the present invention has a cylindrical core made of hard polyvinyl chloride, polyester, paper (tube), aluminum, etc. with an appropriate thickness, and covered with the elastic sheet with a thickness of about 0.5 to 5 mm. This is what I did. e Measurement method (1) Stress at 5% elongation of coating material ( _F5 value) Using an Instron type tensile tester, test a tanzak-shaped sample with a width of 10 mm at a chuck distance of 50 mm and at a tensile speed.
Stretch at 50mm/min (100%/min). Read the stress (Kg) at 5% deformation and use it as the _F5 value. (2) Surface hardness of core when covered JIS A rubber hardness tester (spring type hardness test)
JIS K6301-1975). It is a comprehensive practical characteristic of core hardness, coating material hardness, and coating material thickness. f Examples and Comparative Examples The present invention will be explained in detail below with reference to Examples. The evaluation method for each characteristic value in the examples is as follows. (1) Transfer length This is expressed as the length of the longer transfer at the beginning of sheet winding, step, or adhesive tape step. The presence or absence of transfer is determined by visually inspecting the sheet that has been peeled off from the roll and lightly weighing it down. The take-up roll is 50 mm for magnetic coated webs.
Measurements are taken after being left at ℃ for 72 hours, or in the case of other sheet materials, after being left at room temperature for 1 month. (2) Difficulty in forming the coating layer Workability and finishing conditions when winding the coating sheet around the core (gaps and tension between the winding start and end of the coating layer), and if polishing is required. Workability: A: Excellent, B: Fair.
Evaluation is made on a four-level scale: C: Slightly inferior, and D: Poor. (3) Handling properties The generation of scratches and dirt during handling, mainly during one-way use, should be handled in accordance with 4.
Evaluated in stages. (4) Recyclability Characteristics during repeated use, such as recovery of deformed parts, peelability of the adhesive tape (residual adhesive or damage when peeled off), and surface stain resistance, were evaluated in the same 4-point scale as in Item 2. Examples 1 to 3 Winding cores were created as follows. That is,
A hard polyvinyl chloride pipe with a diameter of 6 inches and a length of 382 mm was used as the hard core, and the elastic sheet shown in Table 1 was used as the elastic sheet.
This artificial leather is made by applying an adhesive to a hard polyvinyl chloride tube and cutting it into specified dimensions. A winding core was created by pasting it on and covering it with artificial leather.
In addition, the 5% tensile elongation stress of artificial leather is 1.0 Kg/cm for 1.5 mm thick, 1.7 Kg/cm for 2.5 mm thick,
The 4.5mm thick one weighed 3.1Kg/cm. A coated web (thickness: 75 μm, width: 380 mm) for a floppy disk with a length of 2000 m was wound onto this core and evaluated. The coated web that is still wound around the core is heated to 50℃.
The splice mark (transfer length) was within 25 m when left for 72 hours. Details of the results are shown in Table 1. Other characteristic values are also listed in Table 1. Comparative Examples 1 to 3 When a polyethylene terephthalate film and a coated web based on the same film were wound around a hard polyvinyl chloride core or paper tube (not covered with an elastic material: surface hardness of 97 to 99 degrees). Experiments were conducted to investigate the occurrence of splice marks. The film (not coated with magnetic coating) was left at room temperature for two months, and the coated web was left at 50° C. for 72 hours in the same manner as in Example 1, and then predetermined characteristic values were evaluated. Comparative Example 1
-3 in Table 1. Examples 4 to 8 In Example 4, a different web (50μ
(magnetic recording material with sputter-deposited elastic layer)
We tested the conditions when the material was wound up. The results are shown in Table 1. Example 5 is an example in which a 5 μm thick polyethylene terephthalate film is wound around a core in which the hard core is a paper tube and the same artificial comparison as in Example 1 is used as the elastic sheet. 2
An example in which a synthetic comparison was used as an elastic sheet in place of an artificial comparison, in which a raised polyester knit was impregnated with a polyurethane resin and applied to its surface.
Example 7 is an example in which a paper tube is used as the hard core, and a two-layer sheet with the artificial leather of Example 1 as the lower layer and the synthetic leather of Example 6 as the upper layer is used as the elastic sheet, Example 8
This is an example in which the surface application of polyurethane resin was omitted in the artificial leather of Example 2, and it was confirmed that the intended purpose was achieved in all cases. In addition, the 5% tensile elongation stress of the elastic sheet in the above examples is all 0.35.
It was over Kg. The results of these Examples are also shown in Table 1. Comparative Examples 4 and 5 A hard core body is coated with an elastic body, but the comparative examples are made of hard thin polyester nonwoven fabric (thickness
0.25 mm), and the surface hardness of the winding core was as hard as 93 degrees (Comparative Example 4).
On the other hand, the coated winding core made of flexible thick polyester non-woven fabric (thickness 5 mm) subjected to resin treatment has a surface hardness of 51 degrees and is extremely flexible (Comparative Example 5). When a coated web was wound using these cores, the core with a hard surface (Comparative Example 4) was difficult to handle and caused process troubles.

[Table] * Deformation occurred on the surface. On the other hand, it was found that the flexible winding core caused folds and wrinkles in the coated web, which caused problems in practical use. g Effects of the Invention According to the present invention, a roll with a good winding appearance can be obtained by winding a web using a core having an appropriate surface hardness. In addition, there is no transfer of wrinkles or steps on the web, and there is an advantage that the web wound onto a roll can be used with almost no loss. The effect is particularly great in magnetic recording media where the base film is thick and transfer of steps directly causes product defects, especially magnetic recording media for floppy disks. The winding process using the winding core of the present invention is extremely stable, with very little air entrapment between the web layers, making the work easier and increasing production efficiency.

Claims (1)

[Claims] 1. A winding core for winding a continuous web, in which the outer surface of a cylindrical hard core is coated with a soft elastic material,
The soft elastic body has a surface hardness of 55 to 90 degrees when covered with the hard core, and has a surface hardness of 5%
A winding core characterized in that it is formed from an elastic sheet impregnated with and/or coated with an elastic resin with a stress of 0.35 kg or more per 1 cm width during tensile elongation and a fibrous porous structure that maintains porosity. 2. The winding core according to claim 1, wherein the elastic sheet is artificial leather based on nonwoven fabric. 3. The winding core according to claim 1, wherein the continuous web is a magnetic recording medium.