JPH0148955B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for manufacturing a flat multilayer adhesive sheet,
In particular, it concerns a method for manufacturing a flat multilayer adhesive sheet using a winding method using a large-diameter drum, and its purpose is to improve the conventional drawbacks of this method,
An object of the present invention is to provide a method for efficiently producing a flat multilayer adhesive sheet that has good flatness and does not undergo deformation. A film formed by laminating a large number of films coated with an adhesive to form a flat plate is used, for example, as a dust removal sheet and other appropriate uses. Dust removal sheets are placed on the floor at the entrance of rooms where dust should not enter, and are used to remove dust adhering to the floor of occupants' shoes and tires of trolleys, etc., and when the surface becomes dirty due to dust absorption, The adhesive is peeled off one by one to expose a new adhesive surface. In addition, there are multilayer adhesive sheets formed into flat plates for use by sequentially peeling adhesive films as needed, and all of them require good flatness. When manufacturing such a flat multilayer adhesive sheet, rather than stacking sheets one by one, a film with an adhesive surface is wound around a large-diameter drum until the required thickness is reached. The method of cutting the sheet in the axial direction and expanding it to obtain a multilayer sheet is relatively often adopted because of its high productivity. However, if this method is simply carried out using the conventional winding method, the thickness increases as the layer is wound, as shown in Figure 1, so the outer circumference (b) and inner (a) of the wound laminate increase. The length of is π(R+2d)
The difference is -πR=2πd, and as a result, when the drum is cut in the axial direction and opened to form a plate, a cavity 2 is created inside as shown in the cross section as shown in Figure 2, and it bulges outward in a ridge shape. A so-called gearing phenomenon occurs in which ivy protrusions appear. In addition, it has a tendency to return to an arcuate shape and tends to curl inward. In order to temporarily eliminate this, so-called aging, which involves pressing with a flat plate for a long time while heating, is required, which not only significantly reduces productivity, but also poses a risk of reoccurrence. The present invention improves these drawbacks, and after cutting, the film located on the outer side of the laminate is wound up so that the degree of shrinkage is increased sequentially, that is, the shrinkage stress is made different between the inner and outer sides. This prevents the occurrence of gearing and allows the entire laminated layer to be naturally and properly maintained in a flat plate shape. That is, the present invention involves applying an adhesive to a synthetic resin base film, winding it around a large-diameter drum, and cutting the film wound on the drum in its axial direction to produce a flat multilayer adhesive sheet. The difference in shrinkage rate of the film from the beginning to the end of winding is 2πd±R/100 (where d=laminated thickness of drum-shaped film, R
=Drum diameter) This is a method for producing a flat multilayer adhesive sheet, which is characterized by winding the sheet while gradually increasing the tension so that it becomes . Unlike conventional methods, tension is not applied from beginning to end,
Alternatively, if the material is wound and cut in a constant state throughout, the shrinkage stress of each layer will be equal, and the cylindrical outer layer will be sequentially longer in length than the inner layer. As a result, if a cylindrical shape in which these are integrated is forcibly transformed into a flat plate, the long outer layer will bulge out. Therefore, if the outer film is wound in such a manner that the outer film has a sequentially larger shrinkage stress, then when it is cut into a flat plate,
Since the degree of contraction is greater on the outer side, this phenomenon is prevented. Based on this knowledge, the present inventors conducted various studies and found that by winding the film while gradually increasing the tension so that the difference in shrinkage rate of the film from the beginning to the end of winding is 2πd±R/100, The present invention was achieved by recognizing that it can be made into a flat plate shape without causing gearing and does not cause deformation. If the above range is exceeded, the tension on the outside is too strong and the outside b
This results in curling or exceeding the elastic limit and conversely decreasing the shrinkage rate, resulting in gearing. On the other hand, if the tension is less than the above range, gearing similar to the conventional one occurs and sufficient effects cannot be obtained. EXAMPLES Hereinafter, the structure and effects of the present invention will be explained in detail with reference to Examples and Experimental Examples. As shown in Fig. 1, a 500 mm wide raw film 1' made of a 55 μ thick polyethylene film coated with an acrylic adhesive to a coating thickness of 5 μ is sent out from an unwinder 4 and wound onto a large diameter drum 5. When it reached a predetermined thickness, it was cut, removed from a large-diameter roll, and rolled out to form a flat multilayer adhesive sheet. 6 is Tatsuchiroru. The unwinding machine 4 was adjusted to a constant torque, and the winding speed on the large-diameter drum 5 was gradually increased linearly to wind it up, and after cutting, it was left in a flat plate shape for 2 days. The results of various experiments conducted under the following conditions are shown in the table. Length on large diameter drum (A): Test No. 1 to 6 R = 320 mm, d = 1.8 mm (30 layers) Inner length 320 x π = 1005 mm Outer length (320 + 1.8 x 2) π = 1017 mm Test No.7~11 R=500, d=3.0mm (50 layers) Inner length 500×π=1571mm Outer length (500+3×2)π=1590mm Winding speed: Speed at the beginning and end of winding (gradually linearly ) Length when flattened (B): After 2 days, peel off the top layer (a) and bottom layer (b) and measure (A) - (B): Amount of shrinkage on the inside and outside [( A) - (B)] (outside) - [(A) - (B)] (inside): Difference in shrinkage amount between outside and inside Suitable range (range of the present invention): Test No. 1 to 6 2πd± R/100=2π×1.8±320/100=11.3±3.2 Test No.7 to 11 2πd±R/100=2π×3±500/100=18.8±5.0 As you can see from the table, the difference in shrinkage amount is 2πd± Nos. 2, 3, 4, 9, and 10 corresponding to R/100 showed extremely good results, and it was recognized that the object of the present invention was achieved. On the other hand, Nos. 1, 7, and 8 cause gearing and curling, and Nos. 5 and 11 are good at preventing gearing, but curl outwards. On the other hand, No. 6 has too strong tension, and conversely the amount of contraction decreases, causing gearing and curling. As described above, according to the present invention, a flat multilayer pressure-sensitive adhesive sheet that does not cause gearing or curling can be obtained by winding the sheet without requiring aging treatment or complicated processes, and is extremely effective. 【table】

[Brief explanation of drawings]

FIG. 1 is a side view schematically showing how the base film is wound up, and FIG. 2 is a side view of a flat multilayer adhesive sheet in which a gearing phenomenon has occurred. 1...Adhesive film layer, 1'... Original adhesive film,
2...Cavity, 3...Wavily shaped bulge (gearing),
a...inside, b...outside.

Claims (1)

[Scope of Claims] 1. A synthetic resin base film is coated with an adhesive and wound onto a large-diameter drum, and the film wound on the drum is cut in its axial direction to produce a flat multilayer adhesive sheet. In doing so, the difference in shrinkage rate of the film from the beginning to the end of winding is 2πd±R/100 (where d=thickness of the film stack on the drum, R
= drum diameter) A method for producing a flat multilayer adhesive sheet, characterized by winding the sheet while gradually increasing the tension so that