KR20130107012A - Mold release agent for vulcanization molding of tire - Google Patents

Abstract

PURPOSE: A release agent for vulcanizing tires is provided to improve release properties and lubricating properties without increasing the silicone or inorganic powder content and to reduce a rate generating defective products when tires related to the release agent are molded. CONSTITUTION: A release agent for vulcanizing tires is coated between a tire and a bladder when the tire is vulcanized. While the release agent contains inorganic powder including mica in the aqueous emulsion of silicone, the average particle diameter of the mica is in a rage of 55-95 micrometers.

Description

Release agent for tire vulcanization molding {MOLD RELEASE AGENT FOR VULCANIZATION MOLDING OF TIRE}

TECHNICAL FIELD This invention relates to the mold release agent for tire vulcanization which improved the mold release property and lubricity by specifying the average particle diameter of a mica.

In general, vulcanization of tires is performed by filling a rubber bag-shaped bladder with a high-temperature, high-pressure heating and pressurizing medium such as steam in a hole of an unvulcanized tire mounted in a vulcanizing mold. And heating the outer surface of the unvulcanized tire by pressing the vulcanized mold tightly. At this time, the lubrication between the unvulcanized tire and the bladder is improved, the air entering between the unvulcanized tire and the bladder is discharged, and the release property from the tire of the bladder after vulcanization is released. In order to improve, the release agent is previously coated on the inner surface of the unvulcanized tire.

As such a mold release agent, for example, as described in Japanese Patent Application Laid-open No. Hei 5-301229 or the like, based on an aqueous emulsion of silicone or an organic solvent solution of silicone, the base is mica, A method of adding inorganic powder such as talc has been proposed. In recent years, an aqueous emulsion is used as a base from the viewpoint of safety and ease of handling.

However, such an aqueous emulsion tends to be poor in releasability and lubricity compared with organic solvents because it is likely to be splashed on the surface of the tire and easily stained when applied. Therefore, while relatively increasing the content of silicon and inorganic powder is performed, there is a problem in that it causes an increase in cost and it is difficult to sufficiently improve the lubricity in particular. In addition, the lack of lubricity leads to deformation of the tire, meshes with tire beads of the bladder, and causes the occurrence of deterioration of the bladder.

In view of such a situation, the present inventors have focused on and studied mica in inorganic powder. As a result, it was confirmed that when the fine particles having an average particle diameter of 55 micrometers or more were used as mica in the inorganic powder, the lubricity could be improved while securing the necessary release property.

Moreover, in the conventional mold release agent, the small particle | grains whose average particle diameter is about 2-40 micrometers have been used from the viewpoint of dispersibility etc. for mica.

The present invention has been made to solve the above problems, in the release agent based on the aqueous emulsion of silicone (silicone), as the mica based on the use of alleles having an average particle diameter of 55 micrometers or more It is an object of the present invention to provide a mold release agent for tire vulcanization which can suppress the increase in cost to the maximum and further improve the lubricity while securing the necessary mold release property.

The invention of claim 1 is a mold release agent for tire vulcanization which is applied between a tire and a bladder during tire vulcanization, and includes at least mica in an aqueous emulsion of silicone. In addition to containing the inorganic powder, the average particle diameter of the mica is in the range of 55 micrometers to 95 micrometers.

In the invention of claim 2, the content of the mica is in the range of 6% by weight to 30% by weight based on the entire release agent.

In the invention of claim 3, the inorganic powder is composed of the mica and talc, and the content of the inorganic powder is in the range of 20 to 50% by weight based on the entire release agent.

Since this invention is comprised as mentioned above, the increase of cost can be suppressed as much as possible, and lubrication property can be improved, ensuring necessary release property.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The mold releasing agent of the present invention is a mold releasing agent applied to the inner surface of an unvulcanized tire during tire vulcanization molding, and containing an inorganic powder containing at least mica in an aqueous emulsion of silicone. At the same time, the average particle diameter of the mica is regulated within the range of 55 micrometers to 95 micrometers.

Here, the aqueous emulsion (silicone emulsion) of the silicone (silicone) (hereinafter referred to as silicone emulsion) is the oil in the water dispersed in water in the form of fine particles of silicone (silicone) having a releasing action in the form of fine particles according to the emulsifier It is a droplet emulsion.

In addition, the silicone (silicone) is a generic term for polysiloxanes, and may include silicone oil, silicone rubber, and silicone resin. However, from the point of view of releasability, since the molecular structure is not linear, the degree of polymerization is low, and silicone oil having a fluidity at room temperature, for example, dimethyl silicone oil, may be suitably applied. . The silicone oil is particularly preferably at a viscosity of 25 to 500,000 cSt, and more preferably 300 to 100,000 cSt at 25 ° C. The viscosity is too low to release the release effect, and conversely too high. The problem arises that it is difficult to obtain a stable emulsion.

In addition, the inorganic powder added to the said silicone emulsion (silicone emulsion) contains the at least mica, and this example illustrates the case where it consists of mica and talc. Such mica and talc have conventionally been used as an agent for improving releasability and lubricity, and have exhibited some improvement effect, but have not reached a level that can be satisfactorily satisfied in terms of lubricity.

However, as a result of the present inventor's research, the lubrication between the bladder and the tire bore surface was obtained by using an allele having the average particle diameter within the range of 55 micrometers to 95 micrometers as the mica. It is confirmed that it can significantly improve the activity). In the case of using mica, which is a fine particle having an average particle diameter of about 2 to 40 micrometers as in the prior art, the dispersibility becomes high because the mica direction becomes irregular, and the indirect mica is constrained to rubber. It is assumed that the smoothness and low friction of the mica surface are not sufficiently utilized.

Therefore, when the said average particle diameter is made smaller than 55 micrometers, it is difficult to obtain a satisfactory lubricity improvement effect. However, if the average particle size is larger than 100 micrometers, it may cause abnormal dispersion or the spray gun to be full. Therefore, it is more preferable to make the said average particle diameter into the range of 55-95 micrometers.

Moreover, in talc, the lubricity improvement effect is not expected also with the increase of the average particle diameter, Therefore, from a dispersible viewpoint, the average particle diameter of talc is smaller than the average particle diameter of mica at least, It is preferable to set it as the range similar to the conventional one of 1-50 micrometers, and 1-20 micrometers which are more preferable.

In addition, the content of the mica is preferably blended in an amount of 6 wt% to 30 wt% with respect to the entire release agent, and less than 6 wt% makes it difficult to secure necessary mold release properties and lubricity, and deforms the tire during vulcanization. And the bladder meshes with the tire bead, which leads to deterioration of the bladder and the like. In addition, even if the content exceeds 30% by weight, it is not possible to expect a new improvement in mold release property and lubricity, which leads to an unnecessary increase in indirect cost and an abnormality that the appearance is deteriorated because an application village occurs. do. Therefore, as for content of mica, it is good to set it as 6 to 30 weight% more preferable.

From the viewpoint of indirect release property and lubricity, the total content of the inorganic powder is in the range of 6 to 30% by weight based on the entire release agent, and the content of silicone is in the range of 6 to 15% by weight relative to the entire release agent. desirable.

Moreover, as mica, various things, such as mascobaito (white mica), furokobaito (don mica), bio tight, fluorine don mica (artificial mica), are known, for example. Various kinds of mica can be used regardless of the composition component, Mohs hardness, and the like.

In the mold release agent of the present invention, if necessary, other additives such as thickeners and preservatives may be blended in an appropriate amount of, for example, 5% by weight or less of the entire mold release agent. It can deform in various states and can implement, without being limited.

The release agent of the composition shown in following Table 1 was manufactured, apply | coated to the inner surface of an unvulcanized tire, and the incidence rate of the defective product was measured when tire vulcanization was performed.

(1) The incidence of defective goods:

12500 tires were vulcanized and the following four items were judged according to visual inspection for the presence or absence of defects.

* BL / P is the common name of the defective product resulting from the puncture of the bladder used in the vulcanization molding process;

TWIST refers to a mutant defect in a bead portion that occurs because the bead portion of the product tire is caught by the bead ring of the tire mold;

BL / CR refers to a defect in the profits caused by the eating of a bladder between the tire mold and the product tire;

* DEF means the tire deformation;

Comparative Example 1 Example 1 Example 2 Example 3 Silicone emulsion <wt%>
Silicone oil (* 1)
Inorganic powder
Mica (mica) (* 1) <wt%>
Average powder <㎛
Talc (* 2) <wt%>
Average powder <㎛
(* 3) <wt%>

Defective product rate
Total (vulcanized)
(BL / P)
(TWIST)
(BL / CR)
(DEF) 8


13
40
31
15
2


0.143
0.043
0.015
0.023
0.006 10


32
55
7.5
15
0.8


0.139
0.036
0.013
0.025
0.010 12


20
15
21
15
0.8


0.199
0.044
0.030
0.031
0.017 13


19
75
21
15
0.8


0.105
0.015
0.013
0.017
0.012

As shown in Table 1 above, the embodiment can improve mold release properties, lubricity, and especially lubricity without increasing the content of silicone, inorganic powder, and the like, and inferior product incidence rate when forming a tire related to the release agent. It can be seen that can be reduced.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be apparent to those skilled in the art that changes may be made.

Claims (3)

In the case of tire vulcanization, a release agent for tire vulcanization is applied between the tire and the bladder,
The aqueous emulsion of silicone contains at least an inorganic powder containing mica, and the average particle diameter of the mica is in the range of 55 micrometers to 95 micrometers. Release agent for tire vulcanization molding.
The release agent for tire vulcanization molding according to claim 1, wherein the mica content is in the range of 6 wt% to 30 wt% with respect to the entire release agent.
3. The method of claim 2,
The inorganic powder consists of the mica and talc,
The content of the said inorganic powder exists in the range of 20-50 weight% with respect to the whole mold release agent, The mold release agent for tire vulcanization molding characterized by the above-mentioned.