JPH0378261B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a method for manufacturing a rubber printed body having a printed surface with uneven relief on the surface, and more specifically, to a method for manufacturing a rubber printed body having a printed surface with uneven relief, and more specifically, to a method for manufacturing a rubber printed body having a printed surface with uneven relief. When manufacturing a rubber printed body having a cross-sectional structure in which the porous rubber coating layer is integrally formed, the object is to be able to mold the porous rubber coating layer to a desired uniform thickness over the entire surface.

That is, in the rotary stamp as shown in FIG. 1, a belt-shaped rubber printed body A is wound around the rubber printed body A so that it can be rotated by hand, and the printed surface 1 of uneven relief is placed on the surface of this rubber printed body A at regular intervals. It is formed protrudingly. Further, in a rubber stamp as shown in FIG. 2, a rubber printed body A on which a printed surface 1 having a concavo-convex relief is similarly affixed to the lower surface of a rootstock 2. This invention is directed to this type of rubber printed body A.

[Background technology]

If these rubber printing bodies A are molded from a normal non-porous rubber material, water-soluble ink is difficult to get onto the surface (printed surface), and there is a problem in that the impression is blurred when pressed against the paper surface. . This is because there is no means for actively adsorbing and trapping ink on the surface of the rubber printed body A.

Therefore, the present applicant previously proposed a rubber printed body A with a cross-sectional structure as shown in FIG.
No. 194190, No. 58-96086). This figure 3 shows an example of a rubber print body for a rotary stamp, and its basic structure is that an extremely thin porous rubber coating layer 4 is integrally laminated on the surface of a thick non-porous rubber base layer 3. and when it is based on this, the porous rubber coating layer 4
The ink is adsorbed into the fine pores of the paper, and the ink is squeezed out to the surface by compressive deformation during stamping, dramatically improving the transferability of the ink to the paper surface.

Similar to this type of laminated rubber printed material, there is a rubber printed material for automatic stamps intended for continuous stamping. The rubber printed body a in this automatic stamp is
For example, as shown in FIG. 5, a porous second rubber layer 6 with a small porosity is laminated on the surface of a first porous rubber layer 5 with a large porosity, and the ink occluded in the first rubber layer 5 is laminated. This transfers to the second rubber layer 6 and presses the surface of the second rubber layer 6 against the paper surface. In this case, not only the first rubber layer 5 but also the second rubber layer 6 is thick in order to absorb ink. As a result, the overall stiffness is weak, and when pressed against the paper surface, the porous rubber layers 5 and 6 are greatly compressed and deformed as a whole, and the stamp impression becomes sticky and unclear due to excessive ink. In other words, since the compressibility is excessive, a stopper means is essential to prevent the rubber printed body from being pressed too hard. In addition, since the porosity of these porous rubber layers 5 and 6 is generally set to about 60 to 90%, they are naturally fragile, and the printing surface 1 is When protruding, the protruding printed portion is likely to be lost. In any case, the thickness of the porous rubber coating layer 4 in the rubber printed body A targeted by the present invention is
It has a thickness of about 0.05 to 0.5 mm, and is fundamentally different from the rubber layers 5 and 6 in the rubber printed body a of an automatic stamp.

Now, in the production of the rubber printed body A, which is the object of the present invention, conventionally, as shown in FIG.
Liquid unvulcanized rubber substance 4a mixed with a readily soluble substance such as sodium chloride and a solvent such as toluene
Apply a thin layer. Next, the rubber materials 3a and 4a are placed in a mold and simultaneously vulcanized under heat and pressure, and the entire shape including the printing surface 1 is molded. Then, this molded article is placed in a liquid to extract easily soluble substances from the rubber substance 4a, and finally the rubber printed body A is produced by cutting it into a desired width. In this case, a non-porous rubber base layer 3 was formed from the first rubber material 3a, and a porous rubber coating layer 4 was formed from the second rubber material 4a, resulting in the cross-sectional structure shown in FIG.

The problem with this conventional method is that after applying the second rubber substance 4a to the first rubber substance 3a, both rubber substances 3a
The point is that a and 4a are vulcanized and molded simultaneously in one mold. That is, during molding, both rubber substances 3
a and 4a are compressed in the mold so that they have a predetermined uneven relief, but at this time both rubber substances 3
Since both a and 4a are in an unvulcanized state, they flow in the mold. However, the uneven relief to be formed on the print surface 1 of the product rubber print body is not uniform, but varies in size and density. In addition, the first layer constituting the rubber base layer 3
The rubber substance 3a is quite thick, but the second rubber substance 4a constituting the rubber coating layer 4 has a product thickness of 0.05.
It is extremely thin at ~0.5mm. Therefore, the first rubber substance 3a and the second rubber substance 4a may flow and mix in the mold during molding, or the second rubber substance 4a may partially flow thickly or thinly on the surface of the first rubber substance 3a. do.

Specifically, the cross section of a conventional rubber printed body when made into a product is generally as shown in FIG. That is, (1) the second rubber substance 4a is particularly thick at the shoulder 7 in the protrusion of the printing surface 1, and the rubber coating layer 4 becomes thicker than necessary at the shoulder 7; This means that when stamped, the seal impression loses its shape and is no longer sharp.

(2) The second rubber substance 4a largely wraps around into the first rubber substance 3a (the part indicated by reference numeral 8), and the rubber coating layer 4 is formed in a state that it nests even into the rubber base layer 3. . If this happens, the original function of the rubber base layer 3 will be halved and it will become too stiff, which of course will cause the seal impression to lose its shape when stamped.
As the porous rubber coating layer 4 wraps around, the printed portion that protrudes from the corresponding portion 8 is likely to be damaged.

(3) The rubber coating layer 4 is not formed on the protruding end surface of the printing surface 1 excluding the shoulder portion 7, and the rubber base layer 3 is partially exposed (for example, the part indicated by the reference numeral 9). The seal impression is blurred due to part 9. In particular, in the concave bottom surface of the surface of a rubber printed body, in particular, in the rubber printed body for a rotary stamp shown in FIG.
etc., the rubber coating layer 4 is hardly formed. Even if the rubber coating layer 4 is formed in these recesses to a predetermined thickness or is not formed at all, there is no significant problem functionally. However, the rubber coating layer 4 is generally colored blue or the like in order to distinguish it from a rubber printed body made only of ordinary non-porous rubber material (so-called red rubber). There are many parts where the color changes, making it difficult to commercialize.

I think the disadvantage of the conventional method is that even though the depth of the relief on the printing surface 1 is constant, it varies in size (width of the protrusion on the printing surface 1), and sometimes the unevenness is densely packed in a complicated way, and sometimes it is rough. Along with this, when vulcanization molding is performed in a mold, the surface including the rubber base layer 3 is formed into an uneven shape, so the coating thickness of the second rubber substance 4a in an unvulcanized state is This is because even if the thickness is constant, the thickness of the rubber coating layer 4 is naturally affected by the relief when it is manufactured into a product. In general, where the relief is rough, the porous rubber layer 4
There is a tendency for the thickness to increase, and conversely to become thinner in areas where it is denser.

To make matters more difficult, in the case of a rubber printed body having a small overall area of the printing surface 1, the relief on the printing surface 1 is generally fine and dense, so the thickness of the porous rubber layer 4 needs to be set thin. This is because, even when pressed against the paper surface with the same force, when the area of printing surface 1 is small, the receiving pressure per unit area is stronger than that of a larger area. Therefore, in order to prevent printing surface 1 from losing its shape, rubber coating This is because the thickness of layer 4 must be set thin. However, there is a limit to the coating thickness of the second rubber substance 4a because if it is made thinner than a certain limit, a part of the rubber base layer 3 will be exposed to the outside (0.05 mm is the limit according to the inventor's experience). Generally speaking, the rubber coating layer 4 tends to become partially too thick. In other words, when the type size is smaller than size 4, the protruding printed part tends to be completely composed of only the rubber coating layer 4 as shown in Fig. 8, and as a result, the protruding printed part becomes brittle and prone to damage. Easy to accept. Even in a rubber printed body with a large printing surface 1, the thickness of the rubber coating layer 4 on the printing surface 1 will be uneven, and in this case, the rubber base layer 3 tends to break through the rubber coating layer 4 and be exposed to the outside. .

Such unevenness in the thickness of the rubber coating layer 4 will cause the amount of ink contained to vary overall, so when stamped, the impression will lose its shape in some parts and be dark, while in other parts it will be dark. If it gets scratched, it will lead to a bad situation.

In other words, in the conventional manufacturing method, no matter how carefully the coating thickness of the second rubber substance 4a was made uniform, it was inevitable that the relief on the printing surface 1 would cause thickness unevenness in the rubber coating layer 4 after the product. .

[Purpose of the invention]

This invention was proposed in order to eliminate such conventional problems, and basically, in order to obtain a rubber printed body having the cross-sectional structure shown in FIG. Even in such cases, the porous rubber coating layer 4 is intended to be able to be vulcanized and molded uniformly over the entire surface of the printing surface 1.

[Contents of the invention]

In order to achieve the above purpose, after applying an unvulcanized rubber substance 4a containing an easily soluble substance and a solvent to the surface of an unvulcanized sheet-like rubber substance 3a, both rubber substances 3a and 4a are molded into a mold. The conventional method of vulcanization molding at the same time is no good. The second drawback of the conventional method is
Not only the rubber substance 4a but also the thick first rubber substance 3a
The biggest mistake was in vulcanizing and molding them simultaneously and integrally.

Based on this knowledge, the present invention basically provides that the first rubber substance 3a constituting the non-porous rubber base layer 3 and the second rubber substance 4a constituting the porous rubber coating layer 4 have the same shape. The vulcanization molding is performed separately using a mold. Specifically, it will be manufactured through the following steps.

First step: An unvulcanized sheet-like rubber substance 3a is prepared, and it is put into a mold and vulcanized to form a primary molded product 11 having a predetermined relief on the surface. FIG. 4a shows this primary molded product. Note that during this primary molding, it is sufficient to bring the material into a vulcanized state to the extent that it can be shaped, and it is not necessary to completely vulcanize it.

Second step: As shown in FIG. 4b, an unvulcanized liquid rubber substance 4a containing an easily soluble substance 12 and a solvent is uniformly applied to the surface of the primary molded product 11. Although it is conceivable to apply this application with a brush or a spatula, it is preferable to perform the application by spraying with a spray gun. The coating thickness at this time is the thickness necessary to make the rubber coating layer 4 0.05 to 0.5 mm thick when commercialized.
The coating thickness is actually larger by the amount of solvent mixed in. Incidentally, it is practically no problem that a large amount of the rubber substance 4a accumulates in the recesses of the relief.

Third step: The second rubber substance 4a applied to the surface of the primary molded product 11 is air-dried or heated to evaporate the solvent contained therein.

Fourth step: The dried primary molded product 11 is put into a mold having the same shape as the primary molding mold, and the second rubber material 4a is mainly vulcanized and molded to form the first rubber material as shown in FIG. 4c. 3
A secondary molded product 13 is obtained in which the rubber material a and the second rubber substance 4a are integrated. In this case, the same mold as the primary molding mold may be used for the secondary molding, but for reasons of continuous molding, a different mold with the same shape as the primary molding mold may be used. Good too.

Fifth step: The secondary molded product 13 is immersed in a suitable liquid to extract the above-mentioned easily soluble substance 12 to be mixed into the vulcanized second rubber substance 4a.

When the thus obtained sheet-like secondary molded product 13 is cut to produce a product rubber printed body A having a desired shape, the first rubber substance 3a forms the non-porous rubber base layer 3.
In this case, the second rubber substance 4a has the cross-sectional structure shown in FIG. 3, which constitutes the porous rubber coating layer 4.

Here, the rubber substances 3a and 4a constituting the rubber base layer 3 and the rubber coating layer 4 are mutually compatible and are preferably made of the same substance, generally NBR (acnylonitrile butadiene rubber). Natural rubber (NR), polyvinyl chloride, vinyl chloride/vinylidene chloride copolymer, etc. can also be used.

The non-porous rubber base layer 3 is preferably thick and has a rubber hardness of 45° to 70°, more preferably 55° to 66°. If it becomes too soft,
Even if the thickness of the porous rubber coating layer 4 is made as small as possible, it will lose its shape, especially when the area of the rubber printed body A is small. Also, if the rubber base layer 3 becomes too hard,
Not only does it feel uncomfortable to press, but also, especially when the area of the rubber print A is large, the thin porous rubber coating layer 4 cannot adequately adhere to uneven paper surfaces, resulting in partial blurring of the seal impression. It is. The most preferable rubber hardness of the rubber base layer 3 is
The present inventor has confirmed that the angle is within the range of 62° to 64°.

Generally, when the thickness of the porous rubber coating layer 4 exceeds 0.5 mm, its compressive deformability becomes too high, and as with the porous rubber layer found in conventional automatic stamps, the area of the rubber printed body A is affected. Regardless (this is especially noticeable when the seal is small), it retains too much ink, causing the impression to lose its shape and become sticky due to too much ink. On the other hand, if the thickness is less than 0.05 mm, there is a risk that a part of the rubber base layer 3 will be exposed to the outside, and the rubber coating layer 4 will not be able to fully perform its original function of adsorbing and trapping ink. First, when the area of the rubber printed body A is large, even a slight uneven contact with the paper surface will result in poor transfer. Therefore, it is desirable that the thickness of the rubber coating layer 4 be in the range of 0.05 to 0.5 mm. This thickness is determined by the coating thickness when the second rubber substance 4a is applied to the surface of the first rubber substance 3a in the second step described above. However, as units of size for numerical stamps that are commonly used in the industry, extra-large numbers, first numbers, 1st numbers, 2nd sizes, 3rd sizes, 4th sizes, 5th sizes, and 6th sizes are known; for example, extra-large numbers The size of the first issue can withstand use even with a thickness of about 1.5 mm,
On the other hand, if the thickness is less than No. 4, 0.5 mm is too thick and the impression will lose its shape and the ink will become sticky, so this coating thickness is relative. The porosity of the porous rubber coating layer 4 is 60 to 90%, preferably 68 to 70%.
Set to %.

Further, although sodium chloride is generally used as the easily soluble substance, other sugars may also be used as appropriate. Further, the solvent for dissolving the second rubber substance 4a may be toluene or any other rubber solvent.

〔Example〕

An unvulcanized sheet-like rubber material 3a having a thickness of 1.5 to 2.3 mm was placed in a mold to obtain a primary molded product 11 having a predetermined relief on the surface. Next, a liquid unvulcanized rubber substance 4a containing sodium chloride and toluene was sprayed onto the surface of this primary molded product 11 to a thickness of 0.07 mm using a spray gun, and then the unvulcanized rubber substance 4a was dried. Next, the primary molded product 11 after drying
was placed in the same mold used for the primary molding and vulcanization molded again to obtain a secondary molded product 13.The secondary molded product 13 was then immersed in water to dissolve and extract the aforementioned sodium chloride. Finally, it was cut to a desired width to produce a rubber printed body A (numerical stamp) of No. 4 type for use in the rotary stamp shown in FIG. 1, in which the rubber coating layer 4 had a thickness of 0.05 mm. In this case, the thickness of the non-porous rubber coating layer 4 was not affected by the size or density of the uneven relief, and a uniform thickness was obtained over the entire surface.

[Modified example]

FIG. 3 shows a cross-sectional structure of a rubber printed body A for a rotary stamp, but the reinforcing cloth etc. that are integrally bonded to the lower surface of the rubber base layer 3 are omitted for convenience of explanation. Of course, the present invention also covers a rubber printed body A for a rubber stamp as shown in FIG. Furthermore, the uneven relief is fine and printing surface 1
When the total area of the rubber base layer 3 is small, an intermediate layer having a rubber hardness harder than the rubber base layer 3, for example, about 70° to 90° is interposed between the rubber base layer 3 and the rubber covering layer 4. The present invention also anticipates such modifications, and in this case, the rubber base layer 3
After vulcanization molding is carried out in a state in which the intermediate layer and the intermediate layer are overlapped, the rubber coating layer 4 is secondarily molded in the same mold.

〔Effect of the invention〕

As explained above, according to the present invention, in order to manufacture a rubber printed body A having a cross-sectional structure in which a thick non-porous rubber base layer 3 and a thin porous rubber coating layer 4 are integrally laminated, first, An unvulcanized sheet-like rubber substance 3a constituting the non-porous rubber base layer 3 is vulcanized in a mold, and then a thin porous rubber coating layer 4 is formed on the surface of this primary molded product 11.
After the second rubber substance 4a constituting the rubber material was uniformly applied, it was vulcanized and second-molded using a mold of the same shape. In other words, during this secondary molding, the rubber coating layer 4 is thinly molded along the uneven relief of the rubber base layer 3 that has already been primarily formed, so the rubber coating layer 4 is formed on the relief of the printing surface 1. It can respond well to the size and density of the material, and can be finished with an even and uniform thickness over the entire surface. Furthermore, since the defective molding portions during the primary molding are corrected during the secondary molding, the relief also has the advantage of being sharp and neatly finished.

[Brief explanation of drawings]

FIG. 1 is a partially vertical front view illustrating a rotary stamp using a rubber print object, which is the object of the present invention. Second
The figure is a perspective view illustrating a rubber stamp using a rubber printed body to which the present invention is applied. FIG. 3 is a sectional view of a rubber printed body obtained by the method of the present invention, and FIGS. 4 a, b, and c are respective schematic sectional views sequentially illustrating the manufacturing process of the rubber printed body. FIG. 5 is a cross-sectional view showing the cross-sectional structure of a porous rubber printed body in a conventional automatic stamp. FIG. 6 is a schematic sectional view showing the state in the middle of the manufacturing process in a conventional example of the rubber printed body to which the present invention is applied, and FIGS. 7 and 8 show the defective state of the rubber printed body obtained by the conventional method. FIG. 1...Printed surface, 3...Non-porous rubber base layer,
3a... unvulcanized sheet rubber material, 4... porous rubber coating layer, 4a... liquid unvulcanized rubber material,
11...Primary molded product, 12...Easily soluble substance, 13
...Secondary molded product.

Claims (1)

[Claims] 1. To manufacture a rubber printed body A in which a porous rubber coating layer 4 is thinly and integrally laminated on the printing side surface of a non-porous rubber base layer 3, an unvulcanized sheet-like rubber substance 3a is placed in a mold. A process of obtaining a primary molded product 11 having a predetermined relief on the surface by vulcanization molding within a chamber, and uniformly applying an unvulcanized liquid rubber substance 4a containing an easily soluble substance and a solvent to the surface of this primary molded product 11. A method for producing a rubber printed body, comprising the steps of: vulcanizing the primary molded product 11 in a mold of the same shape to secondary mold it; and extracting the easily soluble substance from the secondary molded product 13.