WO2017091004A1

WO2017091004A1 - Method for treating surface of tire mold in order to improve releasing property

Info

Publication number: WO2017091004A1
Application number: PCT/KR2016/013619
Authority: WO
Inventors: 조병우
Original assignee: 조병우
Priority date: 2015-11-24
Filing date: 2016-11-24
Publication date: 2017-06-01
Also published as: KR101726076B1

Abstract

A method for treating the surface of a tire mold according to the present invention comprises: a preprocessing step for cleaning the surface of a tire mold; and a coating forming step for applying a liquid-state coating solution, which is made of a material that is hydrophobic and oleophobic, to the surface of the preprocessed tire mold, thereby forming a coating on the surface of the tire mold, wherein the coating, which is formed on the surface of the tire through such a process, improves the releasing property of the tire mold and effectively solves the problem of adhesion of tire rubber.

Description

Surface treatment method of tire mold to improve release property

The present invention relates to a surface treatment method of a tire mold, and more particularly, to a surface treatment of a tire mold that can greatly improve the mold release property of the tire mold used in the vulcanization process of the tire, thereby semi-permanently preventing adhesion contamination by tire rubber. It is about a method.

In the vulcanization process of the tire, the green tire completed in the molding process is put into the vulcanization mold of the tire (hereinafter referred to as 'tire mold') and subjected to heat and bladder pressure inside and outside for a certain period of time, thereby allowing sulfur and It is a process in which rubber molecules are completely bonded to obtain a stable tire characteristic, and a tire mold makes a unique tread design of a tire.

These tire molds are mainly made of aluminum, and most of today's tire molds have an eight-piece central mold and sidewalls that are circumferentially assembled to form a tread part in direct contact with the road surface. It consists of two side molds assembled on both sides of the center mold to form walls and beads. Each mold consists of a mold part for making an external shape of a tire, for example, a tread and a sidewall part, and a mold connecting part for connecting with another mold. In particular, the mold release property of the center mold and the side mold is important. Is evaluated.

However, the vulcanization process proceeds at a relatively high temperature of about 150 ° C., but the adhesiveness of the tire rubber is increased by the high temperature environment, which causes the tire rubber to adhere to minute scratches or curved portions of the tire mold surface. If this happens, adhesion contamination accelerates. Moreover, since aluminum has a weakness in that mold releasability is poor, contamination due to adhesion of tire rubber occurs easily.

In this way, if adhesive contamination by tire rubber is started, it will damage the appearance of the tire and it will be impossible to produce a tire with a beautiful appearance. Therefore, the tire mold is separated from the vulcanizer and shot blasting (aka 'sanding') Will be decontaminated by However, the separation, decontamination and reassembly of tire molds takes about three hours. If the total number of vulcanizers is 1,000 and four tires are produced in one vulcanizer per hour, Even if the pollution is removed once a month, 12,000 production losses (4 × 3 hours × 1,000 units) are generated during the month alone. Therefore, solving the problem of sticking contamination of the tire mold has a great influence on the productivity improvement.

For this reason, various techniques have been proposed to easily remove rubber adhesive contamination of tire molds or to prevent adhesive contamination.

For example, 'Patent Document 1' introduces a technique for removing precipitation rubber from a tire mold with a ring-shaped blade operated by a control motor, and 'Patent Document 2' describes fluorine resin (trade name) on the inner surface of a tire mold. Teflon ') is proposed to improve the release properties by coating.

However, the removal of adhesive contamination with the blade may damage the tire mold and accelerate the adhesion contamination in the long run.Teflon is applied to the tire manufacturing process because it emits toxic substances including carcinogens at high temperature and high pressure. It is not suitable for the following and moreover, the release property may be secured, but there is a problem that the durability is insufficient.

Therefore, there is a high demand for development of a tire mold having improved releasability that can effectively prevent adhesive contamination from occurring in the tire mold.

(Patent Document 1) Korean Patent Publication No. 2015-0045631 (published April 29, 2015)

(Patent Document 2) Korean Patent Publication No. 2006-0087845 (August 03, 2006)

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for surface treatment of a tire mold that can semi-permanently suppress the occurrence of adhesive contamination in the tire mold during the vulcanization step by improving the releasability of the tire mold.

The surface treatment method of a tire mold according to the present invention includes a pretreatment step of cleaning a surface of a tire mold; and coating a surface of the tire mold by applying a liquid coating liquid of hydrophobic and oleophobic material on the surface of the pretreated tire mold. It includes; forming a film to form.

Here, the liquid coating liquid is characterized in that the ceramic of 10 to 50nm.

The liquid coating solution is sprayed onto the liquid nano ceramic to form a film on the surface of the tire mold, and hardened by applying heat.

In addition, pigments such as white may be added to the liquid nanoceramic.

On the other hand, according to an embodiment of the present invention, after the pretreatment step may further include a durable layer forming step of enhancing the surface durability of the tire mold by spraying a mixture containing alumina and titania or nickel and chromium.

At this time, the film forming step is a step of forming a film by applying a liquid coating liquid of hydrophobic and oleophobic material on the surface of the durable layer so that a plurality of pores existing on the surface of the durable layer is filled.

The method may further include a masking step of concealing a portion where surface treatment is unnecessary before the pretreatment step.

In the method for surface treatment of a tire die according to the present invention, the thickness of the durable layer is preferably 40 to 80 m in the mold part and the side wall connection part among the tire molds, and 130 to 160 m in the central mold connection part. .

The method may further include a planarization step of performing shot blasting so that the surface roughness of the durable layer becomes Ra 1 or less after the durable layer forming step.

Meanwhile, in one embodiment of the present invention, the tire mold in which the film forming step is performed immediately after the pretreatment step may be a side mold forming a sidewall portion of the tire.

Further, in one embodiment of the present invention, the tire mold in which the durable layer forming step is performed after the pretreatment step may be a central mold forming the tread portion of the tire.

According to the surface treatment method of a tire mold according to the present invention, by forming a hydrophobic / oleate film which gives a lotus leaf effect on the tire mold surface, it is possible to effectively suppress the occurrence of adhesive contamination on the tire mold.

In addition, since the releasability of the tire mold is dramatically improved, it becomes possible to use the tire mold semi-permanently with only management which is much simpler than the conventional one. That is, even if the release aid having a heat resistance of about 300 ° C. is sprayed by spraying by adjusting the frequency every day or every other day according to the type of tire, the mold release property of the tire mold is continuously maintained.

In addition, it is also possible to provide a tire mold suitable for mass production by further forming a durable layer in addition to the hydrophobic / oleophilic coating.

1 is a schematic flowchart of a surface treatment method of a tire mold according to a preferred embodiment of the present invention.

Figure 2 shows a tire mold consisting of an eight piece central mold and two side molds assembled on both sides thereof.

3 is a cross-sectional view schematically showing a change in the surface state of a tire mold according to the surface treatment method of the tire mold of FIG.

4 is a photographic view of a tire mold processed according to one embodiment of the method for surface treatment of the tire mold of FIG. 1.

5 is a photographic view of a tire mold processed according to another embodiment of the method for surface treatment of the tire mold of FIG. 1.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiments of the present invention, descriptions of well-known configurations that will be obvious to those skilled in the art will be omitted so as not to obscure the subject matter of the present invention.

1 is a schematic flowchart of a method (S100) for surface treatment of a tire mold according to a preferred embodiment of the present invention.

Referring to Figure 1, the surface treatment method (S100) of the tire mold according to the present invention includes a pretreatment step (S10), a film forming step (S20), and a curing step (S30).

The pre-treatment step (S10) removes oil and the like remaining on the surface of the tire mold 10 to be surface-treated to make it clean, thereby forming the film L or the durable layer D to be formed in a subsequent process. ) It is a process to be able to bond well to the surface.

The pretreatment step S10 is usually subjected to shot blasting.

Shot blasting is made by injecting high-pressure steel or metal particles into the compressed air and spraying the tire mold 10 at high pressure. When the shot blasting process is performed, the contaminants existing on the tire mold 10 are physically removed, and a plurality of small uneven parts are formed on the surface of the tire mold 10 as shown in FIG. . That is, particles such as metal or gold steel are injected at high pressure to collide with the surface of the tire mold 10 to form the uneven portion. The size of the uneven portion may be adjusted by the size of the diamond steel or metal particles, the uneven portion increases the surface area as well as the surface adhesive force of the tire mold 10 to be described later hydrophobic and oleophobic coating (L) or durable layer (D) It produces the effect of improving the bonding strength of. In the tire die 10 made of aluminum, the size of the diamond steel or the metal particles is about 80 to 150.

Then, a liquid coating solution is applied to the surface of the tire mold 10 cleaned by the pretreatment step S10 to form a coating L, and a step S30 of applying heat to the coating L is performed.

The film forming step (S20) and the curing step (S30) is to form a surface of the tire mold (10) hydrophobic and oleophobic to prevent adhesive contamination of the tire rubber which is the biggest problem in the tire vulcanization process. That is, to improve the releasability of the tire mold 10.

The methodology of making the surface hydrophobic and oleophobic in order to improve the releasability of the tire mold 10 is accessible in two aspects: structural and properties of the coating material. Looking at the structural aspect, the tire mold 10 has a large number of pores of about 10 ~ 40㎛ size, water microparticles or pores infiltrate water particles or oil particles are difficult to exhibit hydrophobicity and oleophobicity.

Therefore, in terms of structure, by applying a liquid coating liquid consisting of particles having a size of 10 to 50 nm to the pores on the surface of the tire mold 10, the so-called lotus leaf effect is exerted on the tire surface. That is, on the nanoscale, the roughness of Ra 1 or less on the basis of roughness rather than the smoothness makes it easier to exhibit hydrophobicity and oleophobicity because the surface area contacted by water particles or oil particles becomes extremely small. For example, in the case of the lotus leaf surface, only 2 to 3% of the total surface area of the water droplet is in contact with the lotus leaf surface. This is because the surface of the lotus leaf has small projections of several nanometers in size, and the droplets have extremely small contact area with the projections, and the contact angle of the droplets is greater than 90 °, so that water does not penetrate the leaves and flows easily. will be.

In the present invention, since the particles having a size of 10 to 50 nm are applied to the tire surface, and nano-sized irregularities are formed on the surface thereof, tire rubber does not adhere to the surface of the tire mold 10.

In addition, in the properties of the coating material, the lotus leaf effect is further enhanced if the properties of the nanoparticles forming the coating have hydrophobicity and oleophobicity, so that it is more effective to make the material of the coating into a ceramic having hydrophobicity and oleophobicity. Various forms may be used as the ceramic nanoparticles, and liquid nano ceramics may be used. For example, a nano ceramic having a size of 10 to 50 nm in which a composite cyclic multiple structure that connects silicates via an oxygen atom and functional groups such as alkoxy silane and phenol may form a polymer may be used.

Here, it is not preferable that the size of the ceramic nanoparticles is less than 10 nm because it is not easy to manufacture the ceramic particles, and exceeding 50 nm is not preferable because the lotus leaf effect is slowed and the thickness of the film is not easily controlled.

And, the curing step (S30) is a step of hardening by applying heat to the liquid coating liquid is a liquid nano-ceramic, in the embodiment of the present invention by applying heat in an oven at 150 ~ 260 ℃ temperature for 30 to 60 minutes to cure.

In addition, even if the liquid coating liquid of the nano-ceramic used in the present invention, since the vent hole formed in the tire mold 10 is maintained as it is, it does not affect the basic function of the tire mold 10 at all. This can be called.

As described above, in the embodiment of the present invention by applying ceramic particles of 10 to 50nm size on the surface of the tire mold 10 to form the surface of the tire mold 10 hydrophobic and oleophobic, in the vulcanization process during the tire manufacturing process The problem that rubber adheres to the surface of the tire mold 10 can be solved.

On the other hand, not all tire molds may be for mass production. In other words, the prototype produced for research and development, or in particular, the side wall portion is often less than the tread portion required degree of releasability is sufficient to apply the liquid coating liquid immediately after the pretreatment step (S10). That is, FIG. 2 shows an eight-piece central mold 20 circumferentially assembled to form a tread portion in direct contact with the road surface, and a side wall and a bead portion. In order to show the tire mold 10 consisting of two side molds 30 assembled to both sides of the central mold, the side mold 30 forming the side wall portion is to be applied to the liquid coating liquid immediately after the pretreatment step (S10). It can be.

As such, the above-described method for treating the surface of the tire mold (S100) may be applied to all tire molds in which releasability is emphasized. For the mass production tire mold, it is also very important to secure durability together. have. To this end, the present invention provides a durable layer (D) for enhancing the surface durability of the central mold (20) of the tire mold (10) forming the tread portion, especially before forming the hydrophobic and oleophobic na-ra ceramic coating (L). A step S15 of forming in advance may be added.

That is, the alumina (Al ₂ O ₃ ) and titania (TiO ₂ ), or nickel and chromium, having a high hardness to the tire mold 10 whose surface is cleaned through the above-described pretreatment step S10 and having excellent wear resistance are approximately 1: The mixture may be thermally sprayed at a weight ratio of 1 to 4: 6 to form a durable layer D (S15).

In the present embodiment, among the spraying methods, in particular, a plasma spraying method is used. In general, the spraying powder is injected into the flame while releasing the flame at 1000 to 1500 ° C. In the plasma spraying process, a plasma jet (DC arc) is used. Or a high frequency discharge (RF discharge) to generate a high temperature plasma of approximately 12,000 ° C., and a thermal spray material, that is, a mixture of alumina and titania or nickel and chromium, is injected and melted into the plasma to form the tire mold 10. To be welded (see FIG. 3B).

The mixed ceramic of alumina and titania or nickel and chromium, which are the material of the durable layer D, is melted at about 1840 ° C, and the ceramic, nickel, chromium, etc., in which the titania and alumina are mixed, has a high wear resistance and is a tire mold (10). Increase durability.

The durable layer (D) on the surface of the tire mold 10 formed as described above also has a plurality of voids. The durable layer (D) is coated on the durable layer (D) and the liquid coating solution of the hydrophobic and oleophobic material is cured. Forming a film (L) to fill the voids of (see Fig. 3 (c)).

In addition, in order to improve the appearance of the tire, in some cases, the flattening step S16 of lowering the roughness once again by shot blasting the durable layer D may be further performed. This makes the durability of the tire beautiful by having the durable layer D have a roughness of Ra 1 or less on the basis of roughness.

On the other hand, according to the embodiment may further include a masking step (S5) for concealing a portion of the tire mold 10, the surface treatment is unnecessary before the above-described pretreatment step (S10). Masking step (S5) is performed to lower the surface treatment cost and increase the efficiency by blocking the portion that does not need to form the durable layer (D) or hydrophobic / oil coating (L), the last heat curing step ( Masking may be performed using a heat resistant tape capable of withstanding the temperature in S30), that is, a high temperature of 150 to 260 ° C.

FIG. 4 is a photographic view showing one piece (segment) of a tire mold 10 having a series of surface treatments as described above, in particular a central mold 20 forming a tread portion. The tire mold 10 of FIG. 4 is an embodiment in which the durable layer D and the hydrophobic / oleophilic coating L are formed in both the mold portion 1 and the mold connecting portion 2 in a transparent manner.

Here, the metal mold | die connection part 2 can be considered divided into the center metal mold | die connection part which the 8-piece segment molds which comprise the center metal mold 20 adjoin, and the side wall connection part which the assembled center metal mold | die 20 and the side metal mold | die adhere to, Since the center die 20 has a total of eight center die connections, it is necessary to grind the center die connections in order to assemble the center die 20 exactly as designed. Therefore, among the mold connection parts 2, the durable layer D in a center metal mold connection part needs to be formed thicker in order to consider processing allowance. On the other hand, since only one side wall connection portion exists between the center mold 20 and the side mold 30, there is little need to make the thickness of the durable layer D thick.

Therefore, it is preferable to form the thickness of the durable layer D in a center metal mold | die connection part thickly about 130-160 micrometers, and to form relatively thin in the metal mold | die part 1 and sidewall connection part about 40-80 micrometers in thickness.

FIG. 5 is a photograph showing an embodiment in which the durable layer D is added only to the mold part 1, in particular, opaque such as white to the liquid nano ceramic forming the hydrophobic / oleophilic film L. Pigment is added. This is to ensure that even the fine adhesion of the tire rubber is black with the naked eye.

As such, the mold connecting portion 2 frequently contacts the tire mold 10 made of aluminum with the segments and the central mold 20 and the side mold 30 with each other, so that the rubber mold 10 is easily worn to form a gap. Since the liquid may leak, it is highly desirable to form the durable layer D in the mold connecting portion 2.

In addition, since the durable layer D and the hydrophobic / oleophilic coating L are formed in both the mold part 1 and the mold connecting part 2, the entire tire mold 10 is semipermanently releasable and durable, as well as the rubber liquid. The sealing property can be secured.

As described above, the tire mold 10 having improved releasability by the surface treatment method (S100) of the present invention is a simple method of injecting a release aid (usually made of silicone oil as a main ingredient) at intervals much less than in the past. It is possible to use the tire mold 10 almost semi-permanently by management alone, thus greatly improving the time and cost required for the maintenance and management of the tire mold 10, thereby greatly improving the productivity of the entire tire manufacturing process. do.

While the preferred embodiments and embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that the present invention can be modified without departing from the spirit or principle of the invention. Could be. Therefore, the scope of the present invention will be defined by the description of the claims and their equivalents.

10: tire mold

20: central mold

30: side mold

1: mold part

2: mold connection

D: durable layer

L: Hydrophobic / Oleophobic Film

Claims

A pretreatment step of cleaning the surface of the tire mold; And

A film forming step of applying a liquid coating solution of hydrophobic and oleophobic material to the surface of the tire mold to form a film on the surface of the pretreated tire mold;

Surface treatment method of the tire mold comprising a.
The method of claim 1,

The liquid coating solution is a surface treatment method of a tire mold, characterized in that the ceramic of 10 to 50nm.
The method of claim 2,

The liquid coating solution is sprayed with a liquid nano-ceramic to form a film on the surface of the tire mold, the surface treatment method of the tire mold, characterized in that the curing by applying heat.
The method of claim 3,

Pigment, such as a white, is added to the said liquid nano ceramic, The surface treatment method of the tire metal mold | die characterized by the above-mentioned.
The method of claim 1,

After the pretreatment step further comprises a step of forming a durable layer to enhance the surface durability of the tire mold by spraying a mixture containing alumina and titania or nickel and chromium,

The film forming step is a surface treatment method of a tire mold, characterized in that to form a film by applying a liquid coating liquid of hydrophobic and oleophobic material on the surface of the durable layer so that a plurality of pores existing on the surface of the durable layer is filled. .
The method of claim 1,

And a masking step of concealing a portion where surface treatment is unnecessary before the pretreatment step.
The method of claim 5,

The thickness of the said durable layer is 40-80 micrometers in the metal mold | die part and sidewall connection part of the said tire mold, and 130-160 micrometers in the center metal mold | die connection part, The surface treatment method of the tire metal mold | die characterized by the above-mentioned.
The method of claim 5,

And a flattening step of performing shot blasting so that the surface roughness of the durable layer becomes Ra 1 or less after the durable layer forming step.
The method of claim 1,

And said tire mold is a side mold forming a side wall portion of a tire.
The method of claim 5,

And said tire mold is a central mold forming a tread portion of a tire.