JP4592394B2 - Heat-sensitive stencil sheet and method for producing the same - Google Patents

Description

  The present invention relates to a heat-sensitive stencil sheet made only of a thermoplastic resin film and a method for producing the same. A large number of minute recesses are formed on one surface of the thermoplastic resin film.

  As heat-sensitive stencil paper, there are known a multilayer base paper in which an ink-permeable support made of Japanese paper or the like is bonded to a thermoplastic resin film, and a single-layer base paper made only of a thermoplastic resin film. . For example, Patent Document 1 discloses a single-layer base paper. The term “thermoplastic resin film only” in the single-layer base paper referred to here includes the case where an antistatic coating or anti-fusing coating is applied to the surface of the film, and a support is attached to the film. The purpose is to show the case where they are not matched.

By the way, since the heat-sensitive stencil sheet is used in a state of being wound in a roll shape, the heat-sensitive stencil sheet has a curl and tends to curl at its free end when pulled out from the roll. Therefore, in the multi-layer base paper, for example, as shown in Patent Document 2, a paper label is attached to the free end portion to reinforce the free end portion, thereby preventing curling.
JP 2003-39844 A Japanese Patent Laid-Open No. 9-76619

  By the way, in the multi-layer base paper, the film is about 1.5 μm thick and thin, but the support is about 30 to 40 μm thick. Therefore, the multilayer base paper is thick as a whole. On the other hand, the single layer type base paper generally has a thickness of 20 μm or less, and is thinner than the multilayer base paper. In addition, since one surface of the single-layer base paper has a large number of minute recesses, the single-layer base paper has a distortion caused by processing for forming the micro-recesses as residual stress. Yes. Therefore, the single-layer base paper is more likely to curl than the multi-layer base paper.

  If curling occurs at the free end of the heat-sensitive stencil sheet, the conveyance of the stencil sheet may not be carried out smoothly, and the entire stencil printing process may be hindered.

  An object of the present invention is to provide a single-layer base paper that hardly causes curling, and a method for producing such a single-layer base paper.

  The invention described in claim 1 is a heat-sensitive stencil sheet made of only a thermoplastic resin film having a large number of minute recesses formed on one surface thereof, wherein the number of minute recesses is a region other than the end portions on both sides of the one surface. It is characterized by being formed.

  According to a second aspect of the present invention, in the first aspect of the invention, the minute recesses are formed in the vicinity of the both side end portions so as to gradually become deeper to a predetermined depth as they go inward from the both side end portions. Is.

  The invention according to claim 3 is a heat-sensitive stencil sheet made of only a thermoplastic resin film having a large number of minute recesses formed on one surface, and a large number of minute recesses are formed on the entire surface of the one surface. It is characterized in that both end portions are pressed in the thickness direction.

  According to a fourth aspect of the present invention, there is provided a method for producing a heat-sensitive stencil sheet made of only a thermoplastic resin film having a large number of minute recesses formed on one side thereof, wherein a plurality of minute recesses are formed on the entire surface of the one side. And a pressurizing step of pressurizing both side ends of the film in the thickness direction after the recess forming step.

  According to the first aspect of the present invention, since the minute concave portions are not formed at the both end portions, the residual stress associated with the formation of the minute concave portions does not exist at the both end portions. Therefore, the heat-sensitive stencil sheet of the present invention has a portion where curling is unlikely to occur at both ends. Therefore, according to the base paper of this invention, it can suppress that a curl arises in a free end part and a both-ends part as a whole.

  According to the second aspect of the present invention, there is a region where a shallow minute recess exists in the vicinity of both side end portions, and the residual stress existing in the region is small because the depth of the minute recess is shallow. . Therefore, the heat-sensitive stencil sheet of the present invention is less likely to be curled by both side edges as in the case of the heat-sensitive stencil paper of claim 1, but is also less likely to be curled by areas near both side edges. It has become. That is, the heat-sensitive stencil sheet of the present invention can further suppress the occurrence of curling than the heat-sensitive stencil sheet of claim 1.

  According to the third aspect of the present invention, since the both end portions are subjected to pressure processing, the residual stress existing in the both end portions disappears with the formation of the minute recesses. Therefore, the heated stencil sheet of the present invention can suppress curling at the free end and both side ends as a whole, as with the heat-sensitive stencil sheet of claim 1.

  According to the invention described in claim 4, the heat-sensitive stencil sheet described in claim 3 can be obtained.

(Embodiment 1)
FIG. 1 is a perspective view showing a state in which a free end portion 11 of a heat-sensitive stencil sheet 1A of this embodiment wound in a roll shape is pulled out, and FIG. 2 is a sectional view taken along line II-II in FIG. The base paper 1A of the present embodiment is composed of only the thermoplastic resin film 12 and has a large number of minute recesses 14 formed on one surface 13, but the minute recesses 14 are regions other than the both end portions of the base paper 1A. Is formed. That is, in the base paper 1A, the surface 13 is composed of a region 131 where the minute recesses 14 are formed and two regions 132 and 133 which are both end portions where the minute recesses 14 are not formed. The surface of the film 12 may be provided with an antistatic coating or an anti-fusing coating.

  In addition, as a method of forming many micro recessed parts 14 in the surface 13, the well-known method described in Unexamined-Japanese-Patent No. 2003-39844 is employable, for example. For example, specifically, as shown in FIG. 3, embossing processing is performed in which the minute convex portion 15 is pressed against the surface 13 of the film 12.

  By the way, in the base paper 1A, in the region 131 where the minute recesses 14 are formed, distortion due to the processing for forming the minute recesses 14 exists as residual stress, but in the regions 132 and 133, there is a minute amount. Since the recess 14 is not formed, the residual stress does not exist. Therefore, the base paper 1 </ b> A has a portion where no residual stress exists, that is, a portion where curling is unlikely to occur at both ends. Accordingly, the base paper 1A as a whole is less likely to curl at the free end portion 11 and both end portions.

(Embodiment 2)
FIG. 4 is a partial sectional view corresponding to FIG. 2 of the heat-sensitive stencil sheet 1B of the present embodiment. The base paper 1B of the present embodiment is the same as the base paper 1A of the first embodiment except for the following points. That is, the area 131 of the base paper 1B has areas 134 and 135 in the vicinity of the areas 132 and 133. In the regions 134 and 135, the minute recesses 14 are formed so as to gradually become deeper to the depth L of the other minute recesses 14 in the region 131 as they go inward from the regions 132 and 133 side.

  By the way, the distortion resulting from the processing for forming the minute recesses 14 is small when the depth of the minute recesses 14 is shallow. Therefore, the residual stress existing in the regions 134 and 135 is small as compared with other portions of the region 131. Accordingly, the base paper 1B is less likely to curl at the free end portion 11 and both end portions due to the regions 132 and 133, similarly to the base paper 1A of the first embodiment. 11 and both ends are less likely to curl. That is, the base paper 1B is less likely to curl than the base paper 1A.

(Embodiment 3)
FIG. 5 is a partial sectional view corresponding to FIG. 2 of the heat-sensitive stencil sheet 1C of the present embodiment. The base paper 1C of the present embodiment is different from the base paper 1A of the first embodiment only in the following points, and is otherwise the same. That is, in the base paper 1C, the minute recesses 14 are formed in all the regions 131, 132, and 133, and the regions 132 and 133 are pressed in the thickness direction X.

  In addition, the pressurization process of the area | regions 132 and 133 is performed as follows, for example. That is, as shown in FIG. 6, the regions 132 and 133 are pressed by the rollers 21 and 22 having smooth surfaces.

  By the way, the distortion resulting from the process for forming the minute recesses 14 can be eliminated by pressurizing the film 12 in the thickness direction X. Therefore, in the regions 132 and 133 of the base paper 1C, the residual stress disappears due to the pressing process. Therefore, the base paper 1C is less likely to be curled at the free end 11 and both end portions due to the regions 132 and 133, similarly to the base paper 1A of the first embodiment.

(Concrete example)
Conventional heated stencil sheets and base papers 1A, 1B, and 1C of Embodiments 1 to 3 are cut out by being pulled out from the roll by a predetermined length, and in this state, in each of the main scanning direction S1 and the sub-scanning direction S2. The degree of curling was measured and compared. A conventional base paper is one in which a minute recess 14 is formed on the entire surface of one side. Note that the number of the minute recesses 14 per unit area in the region where the minute recesses 14 are formed is the same for both the conventional base paper and the base papers 1A, 1B, and 1C of the first to third embodiments.

  The specific dimensions of the base paper were as follows. That is, in all the base papers, the total length Y was 800 mm, the total width W1 was 320 mm, the width W2 of both end portions (regions 132 and 133) was 15 mm, and the depth L of the minute recess 14 was 8 μm. In the base paper 1B, the width W3 of the regions 134 and 135 is 7 mm, and the amount L1 of change in the depth of the minute recess 14 in the regions 134 and 135 is L / 2. Also, for all the base papers, those having a thickness T of 10 μm and 11 μm were prepared. Further, in the base paper 1C, when T = 10 μm, the thicknesses T1 of the regions 132 and 133 are 8 μm, and when T = 11 μm, the thickness T1 is 9 μm.

  The degree of curling was measured as follows. That is, when curling occurs and the end portion is rounded as shown in FIG. 7, the diameter D of the rounded portion 110 is measured. Further, when the curl is generated and the end portion is lifted as shown in FIG. 8, the lift dimension E is measured. In the case of FIG. 7, it can be determined that the larger D is, the less curling occurs. In the case of FIG. 8, it can be determined that the smaller E is, the less likely curling occurs. Further, it can be determined that curling is less likely to occur in the case of FIG. 8 than in the case of FIG. The measurement results are shown in Table 1.

As apparent from Table 1, in the conventional sheet, but a state of all 7, sheet 1A embodiments 1 to 3, 1B, the 1C, almost a state of FIG. 8, the state of FIG. 7 Even in this case, the diameter D is larger than that of the conventional base paper. Therefore, it can be determined that the base paper of the embodiment is less likely to curl than the conventional base paper.

  Further, in the main scanning direction S1, it can be determined that the base paper 1B and further the base paper 1C are smaller than the base paper 1A because the floating dimension E is small and curling is unlikely to occur.

  Further, in the sub-scanning direction S2, the base paper 1A is in the state shown in FIG. 7, and the base paper 1B is in the state shown in FIG. 7 when T = 10 μm, but the diameter D is larger than that in the base paper 1A and T = 11 μm. In this case, the state shown in FIG. Therefore, it can be determined that the base paper 1B is less likely to curl than the base paper 1A. Further, the base paper 1C is in the state shown in FIG. 8, and the lifting dimension E is smaller than that of the base paper 1B. Therefore, it can be determined that the base paper 1C is less likely to curl than the base paper 1B.

  Since the present invention is a heated stencil sheet made of only a thermoplastic resin film, curling is unlikely to occur, and therefore it can be advantageously used in a stencil printing apparatus and has a great industrial utility value.

It is a perspective view which shows the state which pulled out the free end part of the heat-sensitive stencil paper of Embodiment 1 wound by roll shape. It is II-II sectional drawing of FIG. It is sectional drawing which shows the method of forming a micro recessed part. FIG. 3 is a partial cross-sectional view corresponding to FIG. 2 of a heated stencil sheet of Embodiment 2. FIG. 4 is a partial cross-sectional view corresponding to FIG. 2 of a heated stencil sheet of Embodiment 3. FIG. 6 is a cross-sectional view showing one manufacturing process of the heated stencil sheet of Embodiment 3. It is sectional drawing which shows one reference | standard which measures the grade which a curl produces. It is sectional drawing which shows the other reference | standard which measures the grade which a curl produces.

Explanation of symbols

1A, 1B, 1C Heat-sensitive stencil sheet 12 Thermoplastic resin film 13 Surface 132, 133 region 14 Micro recess

Claims (4)

In a heat-sensitive stencil sheet consisting only of a thermoplastic resin film with a large number of minute recesses formed on one side,
A heat-sensitive stencil sheet characterized in that a large number of minute recesses are formed in a region other than both end portions on one side.   2. The heat-sensitive stencil sheet according to claim 1, wherein the minute concave portion is formed so as to gradually become deeper to a predetermined depth as it goes inward from the both-side end portions in the vicinity of the both-side end portions. In a heat-sensitive stencil sheet consisting only of a thermoplastic resin film with a large number of minute recesses formed on one side,
A large number of minute recesses are formed on the entire surface of the one surface,
A heat-sensitive stencil sheet characterized in that both end portions are pressed in the thickness direction. In a method for producing a heat-sensitive stencil sheet consisting only of a thermoplastic resin film having a large number of minute recesses formed on one side,
A recess forming step for forming a large number of minute recesses on the entire surface of the one surface;
A method for producing a heat-sensitive stencil sheet, comprising: a pressurizing step of pressurizing both side ends of the film in the thickness direction after the recess forming step.

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