JPS58147341A - Plasticized packing - Google Patents

Abstract

PURPOSE:To provide a plasticized packing which has an excellent liquid sealing function, a durable sealing function, and causes no relaxation of stress, and besides, eliminates the need for a complicated manufacturing method, by a method wherein fiber serves a base material, and a rubber, vulcanized by a vulcanizer of a peroxide, is used as a coupling material. CONSTITUTION:Fiber such as asbestos serves as a base material, a peroxide, especially preferably an organic peroxide, such as dicumyl peroxide, is mixed as a vulcanizer of a coupling material consisting of a rubber material being uniformaly mixed between the base materials and vulcanized, and the titled packing is obtained by a conventional hot air vulcanization. This is a packing in which only a surface layer is plasticized and which has an excellent sealing function and causes no relaxation of stress. It has a merit which is a less permanent strain and a reduced heat deterioration. A in a drawing is this invention and has a DuroD hardness of 42 deg.. A comparing product B, having hardness of 59 deg., is fast in a curing progress, and exercises the bad influence on a performance of a packing. The lower a crosslinking density is, the more enoughly a plasticization is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gasket for sealing fluid, and more specifically, to a plastic (plasticized) gasket.

Conventionally, for example, plastic packing has been often used as a packing material such as general-purpose pulp. The #l material of the packing is roughly classified into the fiber 41 base material, and the powder light beak is broadly classified into the binding material. As a base material for embroidery, it is preferable to use fibers that can contribute to improving the strength and maintaining the resilience of the patch itself.
Asbestos is used. Powder light In is also used as a filler for packing materials to prevent seepage and leakage, and to reduce the sliding resistance of, for example, benzyata.
Powders such as mica and talc are used. Further, as the bonding material, it is preferable to use a material that can contribute to improving the sealing performance by improving moldability and flexibility of the packing, and rubber or the like is generally used. However, there is always one thing in the package.
Basically, the characteristics are 1. Excellent D-seal function (capable of sealing fluid with low tightening surface pressure). (The stem torque is low and stable. (Second stress reduction is low.) However, with the conventional seals mentioned above, If this is done, the packing tends to protrude when hot and the stress relief is reduced, which has the disadvantage of increasing leakage.Also, if you try to reduce stress ambiguity, the packing itself This has the disadvantage of lowering the sealing performance and increasing the torque of the λ rubber.Furthermore, the sealing performance has been improved by applying a soft coating such as fluororesin to the surface of the O-packet itself. Although there are other ways to do this, these methods have the disadvantage of being difficult to maintain due to leakage of fluororesin, and are complicated in manufacturing. There has been no material that fully satisfies the conflicting functions of stress relaxation.

The present invention has been made based on the above circumstances, and it is an object of the present invention to provide a packing that has an excellent sealing function and does not cause stress relaxation, and does not require any complicated manufacturing method.

The present invention will be explained in detail below.

First, as mentioned above, the present invention began with the search for what kind of structure the packing should have in order to obtain a packing that has an excellent sealing function and at the same time does not cause stress relaxation. As a result of careful consideration, it was surmised that from the viewpoint of the structure of the packing material, if only the surface layer of the packing material could be made plastic, the above-mentioned conflicting functions could be satisfied. However, several methods have been considered for concrete methods of plasticizing only the surface layer of the packing, but all of them require complicated manufacturing processes and are difficult to implement from an industrial and economic standpoint. It seemed like a means. Therefore, as a result of further investigation, we focused on the binding material made of rubber conventionally used in packing.Usually, the rubber material as a binding material is distributed uniformly and sufficiently between the fiber base materials, such as asbestos fibers. It has become common knowledge to disperse and completely vulcanize the rubber material. For this reason, sulfur vulcanization is used to vulcanize rubber materials. However, in the present invention, in order to plasticize only the surface layer of the packing, peroxide is used as a vulcanizing agent for the rubber material used as the binding material for the packing.

Rubber materials subjected to 710 sulfurization using peroxide have the advantage of low compression set and little thermal deterioration.
Wait for the drawback that air vulcanization is completely unreliable. however,
The problem with the present invention is that it takes advantage of the drawbacks of peroxide vulcanization, and in a packing based on one fiber, the rubber material to be vulcanized is uniformly dispersed and compounded between the base materials. When a peroxide is blended as a vulcanizing agent for the binder, and the packing is obtained by ordinary hot air vulcanization, only the surface layer thereof is plasticized.

As confirmed by the examples described later, the packing according to the present invention obtained in this manner not only exhibits an excellent sealing function, but also has no stress relaxation and may not be as effective as peroxide vulcanization. In combination with these advantages, we have achieved something with a durable sealing function.

In addition, the multiplication product intended by the present invention is particularly preferably an organic peroxide, such as dikyl rubber oxide, benzoyl peroxide, dikyl peroxide, di-t-
Butyl peroxide, dialkyl peroxide and the like are preferred.

The rubber material used as the binder is preferably an elastomer such as polyisolune, butadiene-styrene copolymer, polybutadiene, polysiloxane, propylene hexafluoride-vinylidene heptafluoride copolymer, or butadiene-acrylonitrile copolymer.

In addition to asbestos, the fiber base material is preferably carbon 1, phenol fiber, polyfluorocarbon fiber, aromatic boiamide fiber, etc., but the fiber base material is not particularly limited.

Next, an embodiment of the packing according to the present invention will be shown.

〔Example〕

Diagram Is1 shows the distribution of crosslink density in the cross section of the packings of the invention product A and comparative product B thus obtained.

The lower the crosslinking density, the more plasticized it is. This I! As can be seen from Figure 1, it was found that in the product A of the present invention, only the surface layer of the packing was plasticized.

Furthermore, the results of measuring the leakage characteristics and stem torque are shown in FIGS. 2 and 3, respectively. The results shown in Figure 2 show that J I
These conditions were incorporated into the screw-in globe valve for Sf#1101t#. The results shown in FIG. 3 were also obtained under the same conditions as described above. As shown in FIG. 2 and FIG. 93, the product A of the present invention was smoother, had a smoother pulp operation that resisted stem torque, and had fewer leakage measures than the comparative product B. 6 and dry heat cycle (temperature maintained at 120"C, 3
As a result of testing the stress relaxation degree and durability characteristics due to changes in leakage amount by repeating the valve seat fully open and fully closed 0 times, time 15 ur/cycle, the inventor of the present invention determined that the leakage amount and stem With silk? Although it exhibited good properties with stable HC, Comparative Product B showed hardening of the rubber due to heat degradation, loss of plasticity of the packing, and increased stem silk and leakage. Changes in the performance of the packing during this dry heat cycle durability test are used to observe changes in the properties of the compounded rubber. This means that after the dry heat cycle durability test, the inventive product and comparative product B were A 8 T 1%.
Rubber fI based on l standards! As a result of measuring the cirrhosis using a DuroD, it was 420° for the product A of the present invention, while it was 59° for the product B with the occlusion. In other words, it was found that this chewing product B had a negative effect on the performance of the seal as the hardening progressed.

As described above in detail, the packing according to the present invention has excellent characteristics that should be provided as a packing.

[Brief explanation of drawings]

P4rIn is a graph showing the packing characteristics in the examples according to the present invention, Figure 1!
The figure is a graph showing the amount of leakage versus the packing tightening torque, and Figure 43 is a -f graph showing the stem torque versus the packing tightening torque. Applicant: Nippon Billae Fusuma Co., Ltd. No.C.

Claims (1)

[Claims] A plasticized packing comprising a packing material made of Ill@Usua as a base material, characterized in that the bonding material for the base material is a rubber vulcanized with a perchlorinated vulcanizing agent.