JPS60174682A - Production of elastic porous stamp material - Google Patents

Abstract

PURPOSE:To enable a porous stamp material to be produced efficiently and inexpensively, by a method wherein a thermoplastic resin powder having rubber- like elasticity or a mixture of the resin powder with a vulcanized rubber powder is mixed with a predetermined amount of particulate fibers, and the resultant mixture is molded and sintered. CONSTITUTION:In a mixing step A, a thermoplastic resin powder 1 or a mixture of the resin powder 1 with a vulcanized rubber powder 2 is mixed with a predetermined amount of particulate fibers 3. An elastic thermoplastic resin powder such as a flexible polyvinyl chloride resin powder is used as the resin powder 1. An appropriate amount of a plasticizer, a stabilizer or the like is added to the resin powder 1. A powder of NBR, SBR or the like which is previously vulcanized and contains an appropriate amount of a vulcanizing agent or a stabilizer is used as the rubber powder 2. Crystalline cellulose is used as the particulate fibers 3. The mixed powder 4 prepared in the mixing step A is fed to a molding and sintering step B, in which is it packed into a metallic mold, and is molded and sintered by pressing and heating, thereby obtaining a porous stamp material 5 having uniform open pores.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a porous stamp material having elasticity.

The methods for producing porous stamp materials have traditionally been: (1) kneading soluble salt into unvulcanized rubber, vulcanizing it under pressure and heat to form stamp letters, etc., and then washing with water to dissolve the soluble salt; ■ A method in which soluble salt is mixed with thermoplastic elastomer powder, sintered and molded, and then the soluble salt is eluted by washing with water (Japanese Patent Application Laid-Open No. 57-64526);
■Method of sintering and molding foamed gelled or semi-gelled polyvinyl chloride powder (Japanese Unexamined Patent Publication No. 53-136
No. 067) etc. are generally widely known.

However, the above manufacturing method (2) still has many problems in terms of stabilization of product quality and work efficiency. That is,
If the amount of salt to be mixed is too small, the soluble salt particles will be completely enveloped by the rubber, making it difficult to completely wash and elute the salt particles. As a result, soluble salts are permanently scattered in the rubber, making it difficult to form a uniform open cell.

On the other hand, if the amount of salt is too large, the structural skeleton of the molded open dirt foam becomes weak, causing various problems in practical use. Furthermore, it takes a considerable amount of time to knead soluble salt into clay-like uncured rubber, and it is extremely difficult to preserve the kneaded material, making it difficult to improve work efficiency.
It also requires 3 to 5 hours to wash and elute soluble salts, which has the disadvantage that it is not possible to shorten the production time.

Next, in method (2) above, it is relatively easy to mix soluble salts, and the porosity and pore size can also be easily adjusted. It is possible to obtain an open cell body having the following properties. However, since one culm is required to wash and elute soluble salts, there remains a drawback that it is not possible to significantly shorten η1!1 hours.

Furthermore, in the method (2) above, since soluble salts are not used, problems related to mixing and washing and elution do not occur. However, in order to obtain a stamp material with a predetermined porosity and pore diameter, it is necessary to maintain the foaming ratio of the foam at a predetermined value before caulking and crushing, and the open cell structure in the powder is There remains a major drawback in that the porosity and pore diameter of the open cell are extremely difficult to adjust.

The present invention aims to solve the above-mentioned problems in the conventional manufacturing method of this type of porous stamp material. The present invention provides a method for manufacturing a porous stamp material having rubber elasticity, which can be manufactured with high efficiency and at low cost.

In addition, in the present invention, in order to achieve the above object, a predetermined amount of powdered fiber is mixed into a mixture of a thermoplastic resin powder having rubber elasticity or a thermoplastic resin powder and a vulcanized rubber powder, The basic structure of the invention is to sinter mold the mixture.

Below, based on a manufacturing process diagram showing an example of the present invention,
The present invention will be explained.

In the figure, (A) is a mixing step, in which a predetermined amount of powdered fibers 3 is mixed into the thermoplastic resin powder 1 or a mixture of the thermoplastic resin powder 1 and the vulcanized rubber powder 2.

Examples of the thermoplastic resin powder 1 include soft vinyl chloride powder, styrene-butadiene copolymer powder, Ethyray-vinyl acetate-vinyl chloride copolymer powder, etc., but any thermoplastic resin having rubber elasticity may be used. Even resin can be used. It goes without saying that the thermoplastic resin powder 1 contains appropriate amounts of plasticizers, fillers, stabilizers, etc. that are commonly used in thermoplastic resins.

Further, as the vulcanized rubber powder 2, there are powders such as vulcanized NBR (tolyl-butadiene rubber) and 5BR (synthetic rubber) containing an appropriate amount of vulcanizing agent and stabilizer.

The particle size of the thermoplastic resin powder 1 and vulcanized rubber powder 2 is as follows:
It is desirable that the material has passed through a sieve of at least 80 meshes, preferably 200 meshes.

On the other hand, the average particle size of the powdered fiber 3 is 40 μm.
The most suitable material is crystalline cellulose with a diameter of 120 μm to 120 μm, but it goes without saying that any powdery fiber material may be used.

The amount of the powdered fiber 3 mixed is approximately 45% of the total weight of the mixed powder.
% or less, and the mixing amount is determined according to the desired bubble ratio.

For example, when the bubble rate is (a)%, the average particle size is 1
The mixing amount of the powdered fibers 3 having a diameter of 20 μm is selected to be about 40% by weight. The reason why the amount of powdered fibers 3 mixed is within the range of about 45% or less of the total weight of the mixed powder is due to the mechanical strength of the porous rubber stamp material. If the amount is 45% by weight or more, the final product, the stamp material, becomes extremely brittle, which poses a problem in practical use.

Further, in the mixing step, unlike the conventional case where soluble salt is kneaded into unfluidized rubber, since fine powders are mixed together, dispersion mixing can be carried out very easily.

The mixed powder 4 formed in the mixing step A is subsequently sent to the sintering molding step (B), where the mixed powder 4 is filled into a predetermined molding die and sintered and molded by pressure and heating. As a result, a porous stamp material 5 having uniform open cells is formed. That is, since the voids of the thermoplastic resin sintered body itself and the pores of the powdered fibers themselves are continuously connected, a completely uniform open cell is formed. The heating temperature and heating time in the sintering molding step (B) vary depending on the surface softening temperature and particle size of the thermoplastic resin powder particles used, but the local fusion bond on the particle surface of the thermoplastic resin powder is , the temperature and time may be such that the heating is carried out evenly throughout. For example, when the thermoplastic resin powder used is soft vinyl chloride powder and powdered fibers are mixed with a mixture of soft vinyl chloride powder and rubber powder, the heating temperature is 1400
C-150°C, heating time is about 3 to 10 minutes. In addition, it is selected to be a sintering mold.

0 Next, the present invention will be described in detail with reference to various examples.

Examples (1) (a) Vulcanized N containing vulcanized fjIJ and filler
BR powder (passed through a 200 mesh sieve) 10
A mixture of 0 parts by weight of vinyl chloride paste resin powder, 50 parts by weight, and 10 parts of plasticizer.

(b) 20 parts of powdered crystalline cellulose having an average particle size of 120 μm.

The above (a) and (b) are mixed, the mixed powder is filled into a mold matrix, and heated under pressure at 145° C. for 5 minutes to form a sintered mold. Next, the sintered molded bodies were cut into appropriate stamp material sizes, and each cut was impregnated with the ink prepared in advance, so that about 1% of the total weight of the stamp was occluded in ink.

In the case of a conventional stamp material in which soluble salts are washed and eluted, the amount of ink absorbed is about ω% by weight of the total weight of the stamp material, and compared to this, the amount of ink absorbed is increased about 133 times.

Furthermore, when the stamp material is used as an ink self-sufficient stamp, it is possible to make about 8,000 continuous stamps without any collapse, shrinkage, or deformation of the characters on the stamp.

Example (2) (a) Powder of soft vinyl chloride containing a plasticizer (passed through an 80-mesh sieve) 1 part by weight (b) 1 part by weight of powdered crystalline cellulose with an average particle size of 120 μm The above (a) and (b) are mixed, filled into the same mold matrix as in Example (1), heated under pressure at 150° C. for 3 minutes, and sintered.

When this sintered molded body was cut into a suitable size and impregnated with the same ink as in Example (1), about 70% by weight of the total weight of the stamp material was occluded.

In Example (2), when only the soft vinyl chloride powder is sintered and molded without mixing powdered crystalline cellulose, the amount of ink impregnated in the sintered molded body is approximately 3 of the weight of the stamp material.
The amount was about 0% by weight, and the effect of mixing powdered crystalline cellulose is clearly visible.

In addition to the above, according to the manufacturing method according to the present invention, since it is a mixture of powders, mixing can be easily performed, and since there is no water washing and elution process as in the past, it is possible to significantly shorten the printing material manufacturing time, It is possible to reduce manufacturing costs.

Furthermore, by mixing powdered fibers, it is possible to easily and reliably obtain a stamp material having a uniform pore diameter and pore distribution, as well as appropriate elasticity and mechanical strength. As a result, the amount of ink storage increases significantly, increasing the number of consecutive stamps, and also prevents the characters on the stamp from collapsing, shrinking, or deforming.
A stamp material with excellent practical utility can be produced.

The stamp material produced according to the present invention can be used not only for so-called ink self-contained stamps, but also for ink absorbers for stamp pads, ink rolls, and the like.

[Brief explanation of the drawing]

The drawings are process diagrams for manufacturing a porous stamp material according to the present invention. A Mixing process B Sintering mold process l　Thermoplastic dressing powder 2 Vulcanized rubber powder 3 Powdered fiber 4 Mixture 5 Sintered molded body

Claims (1)

[Claims] A porous material having elasticity characterized by mixing a predetermined amount of powdered fibers with a thermoplastic resin powder having rubber elasticity or a mixture of thermoplastic resin powder and vulcanized rubber powder and sintering the mixture. Method of manufacturing stamp material.