JP6162985B2 - Tire release agent - Google Patents

Description

  The present invention relates to a tire release agent. More specifically, the present invention relates to a tire release agent that exerts a releasing action by being interposed between a tire and a bladder or between a tire and a mold during tire vulcanization molding.

In the tire manufacturing process, vulcanization molding of unvulcanized green tires is usually performed by inflating a rubber bag called bladder with air or steam inside the raw tires and press-molding the unvulcanized raw tires into the mold. Is done by. Usually, in order to perform this process smoothly, a release agent (a release agent for the tire inner surface) is applied in advance to the inner liner surface of the raw tire (hereinafter, the inner surface of the raw tire). The release agent for the inner surface of the tire mainly has the ability to give good lubricity between the inner surface of the raw tire and the bladder (smoothness), the ability to release the air that has entered the inner surface of the bladder and the raw tire and close the two (air) (Permeability) is required, and when the bladder is contracted after the vulcanization is finished, a performance (releasability) that allows the bladder and the inner surface of the green tire to be smoothly peeled off is required. Therefore, a mixed composition of an oil-in-water emulsion of silicones that imparts releasability and a solid particle suspension that imparts smoothness and air permeability is applied as a mold release agent for the tire inner surface. Has been widely practiced.
Similarly, on the outer surface of the tire, a release agent for the outer surface of the tire such as silicones and fluorine compounds has been used so that the tire product can be smoothly removed from the mold after vulcanization.

Patent Document 1 discloses a method of using a composition of an aqueous silicone emulsion and an inorganic powder containing mica having an average particle diameter of 55 to 95 μm as a release agent for the tire inner surface. In Patent Document 2, a release agent for a tire inner surface containing carbon black and lecithin is used. In Patent Document 3, a composition containing a room temperature curable silicone rubber, a fine silicone resin, an inorganic powder, and a solvent is used. Each method used as an agent is shown.
Patent Document 4 discloses a method of using a composition containing a silicone oil, an ether type or polyhydric alcohol ester type nonionic surfactant and an aqueous dispersion medium as a mold release agent in rubber vulcanization molding. It is shown. In Patent Document 5, a composition containing diatomaceous earth, pyrolytic hydrophobic silica, nonionic surfactant, binder, dye, ethyl alcohol and water is used as an aqueous solution of an external release agent for rubber product production. The method is shown.
In these examples, the tire can be vulcanized and molded without any problems, but the components of these release agents remain on the tire surface, causing damage to the outer and inner surfaces of the tire, resulting in a defective product. was there.

JP 2005-193448 A JP-A-5-77242 JP-A-5-301229 Japanese Patent Laid-Open No. 7-124958 JP 05-177639 A

  The problem to be solved by the present invention is to provide a release agent for tires that has excellent release performance and does not cause scratches on the tire surface.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by a mold release agent for tires that uses a silicone component, rubber fine particles, and sulfur powder in combination. did.

Release agent for tire of the present invention, the silicone component, the rubber particles and sulfur powder including.

The silicone component is based on the total amount of the silicone component, rubber fine particles and sulfur powder.
The weight ratio of the minute is 40 to 98% by weight, the weight ratio of the rubber fine particles is 1 to 30% by weight, the sulfur
The weight ratio of the yellow powder is 1 to 25% by weight.

In the tire manufacturing method of the present invention, the tire release agent is used between the green tire and the bladder and / or
Or is interposed between the green tire and the mold, said bladder is thermally expanded to press-fit the raw tire in a mold, Ru manufacturing method der containing vulcanization step of vulcanization molding.

  When the release agent for tires of the present invention is used at the time of tire production, excellent release performance is exhibited, and scratches are not generated on the surface of the obtained tire. Further, the tire release agent can be used between the raw tire and the bladder and between the raw tire and the mold.

Schematic of unvulcanized rubber for evaluation Schematic of unvulcanized rubber for evaluation with release agent for tire inner surface attached Schematic of vulcanized evaluation rubber

First, each component mix | blended with the mold release agent for tires of this invention is demonstrated, and the mold release agent for tires is explained in full detail.
The tire release agent of the present invention is a composition containing a silicone component, rubber fine particles and sulfur powder.

[Silicone component]
The silicone component is a main component that imparts releasability and lubricity to the tire release agent. Silicone is a general term for organopolysiloxanes, and includes silicone oil, silicone rubber, silicone resin, and the like. The silicone component is a component containing these silicones.
Examples of the organopolysiloxane include dialkylpolysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, methylisopropylpolysiloxane, and methyldodecylpolysiloxane; methylphenylpolysiloxane, dimethylsiloxane / methylphenylsiloxane copolymer, dimethylsiloxane Alkylphenyl polysiloxanes such as diphenylsiloxane copolymers; alkylaralkyl polysiloxanes such as methyl (phenylethyl) polysiloxane and methyl (phenylpropyl) polysiloxane; 3,3,3-trifluoropropylmethyl polysiloxane Can do. These organopolysiloxanes may be used alone or in combination of two or more.

As the silicone component, from the viewpoint of releasability, a silicone oil having a linear molecular structure, a low polymerization degree and fluidity at room temperature is preferable. The viscosity is not particularly limited, but the viscosity at 25 ° C. is preferably from 1 to 5 million mPa · s, more preferably from 500 to 500,000 mPa · s, in terms of the balance between releasability and product stability. It is. In the present invention, the viscosity means a value measured with a cone plate viscometer.
As the silicone component, an emulsion of silicone may be used in the production of a release agent for a tire. The weight ratio of the silicone component is preferably 40 to 98% by weight with respect to the total amount of the silicone component, rubber fine particles and sulfur powder (hereinafter, the total amount of these three components may be referred to as the total amount of the three components). It is more preferably 45 to 97.5% by weight, and particularly preferably 50 to 97% by weight. If the silicone component is less than 40% by weight, sufficient releasability may not be obtained. On the other hand, when the silicone component is more than 98% by weight, a sufficient effect of preventing scratches may not be obtained.

The release agent for the tire is a release agent for the tire inner surface interposed between the raw tire and the bladder, and the release agent for the tire outer surface interposed between the raw tire and the mold. The former is different from the former in that the material is rubber / rubber release, whereas the latter is the rubber / metal release. Therefore, the required properties required for the silicone component are not exactly the same between the inner surface release agent and the outer surface release agent, and the preferred range of the weight ratio of the silicone component is naturally different. Moreover, there is a similar difference with respect to the preferable ranges of the weight ratios of rubber fine particles, sulfur powder, water, and the like described below.
In the case where the release agent for tires is a release agent for tire inner surfaces, it is better that the weight ratio of the silicone component is relatively small because, for example, the silicone component may easily cause scratches on the tire product. It is preferably 40 to 90% by weight, more preferably 45 to 88% by weight, particularly preferably 50 to 85% by weight based on the total amount of components. When the silicone component is less than 40% by weight, sufficient release performance may not be obtained. On the other hand, if the silicone component is more than 90% by weight, sufficient scratch resistance may not be obtained.

  In the case where the tire release agent is a tire outer surface release agent, for example, it is preferable that the weight ratio of the silicone component is relatively large, because the tire product is less likely to be scratched and priority is given to the release property. It is preferably 75 to 98% by weight, more preferably 80 to 97% by weight, particularly preferably 85 to 95% by weight based on the total amount. When the silicone component is less than 75% by weight, sufficient releasability may not be obtained. On the other hand, if the silicone component is more than 98% by weight, sufficient scratch resistance may not be obtained.

[Rubber fine particles]
The rubber fine particles are a component for preventing scratches on the tire obtained during vulcanization.
The rubber component constituting the rubber fine particles is not particularly limited, but, for example, natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber and the like are preferable because they are excellent in scratch resistance. You may use together 1 type, or 2 or more types. Among these rubber components, natural rubber and isoprene rubber are more preferable, and natural rubber is particularly preferable.

The average particle diameter of the rubber fine particles is not particularly limited, but is preferably 0.1 to 100 μm, more preferably 0.2 to 50 μm, and particularly preferably 0.5 to 10 μm. When the average particle diameter of the rubber fine particles is smaller than 0.1 μm, a sufficient scratch prevention effect cannot be obtained, and the viscosity of the obtained release agent becomes high, which may hinder the adhesion process. On the other hand, when the average particle diameter of the rubber fine particles is larger than 100 μm, the releasability may be deteriorated. In the present invention, the average particle diameter means a 50% cumulative particle diameter (d50) in the volume distribution of the particle diameter measured by the laser diffraction method.
The weight ratio of the rubber fine particles is preferably 1 to 30% by weight, more preferably 3 to 28% by weight, and particularly preferably 4 to 25% by weight with respect to the total amount of the three components. If the rubber fine particles are less than 1% by weight, the effect of preventing scratches may not be obtained. On the other hand, when the rubber fine particles are more than 30% by weight, sufficient releasability may not be obtained.

As explained above, the required properties required for the rubber fine particles are not exactly the same between the inner surface release agent and the outer surface release agent, and the preferred range of the weight ratio of the rubber fine particles is different as follows. is there.
In the case where the release agent for tires is a release agent for tire inner surfaces, for example, it is generally preferable that the weight ratio of the rubber fine particles is relatively large because the tire product is likely to be scratched by a strong pressure from the bladder. 5-30 weight% is preferable with respect to 3 component total amount, 8-28 weight% is more preferable, and 10-25 weight% is especially preferable. When the amount of the rubber fine particles is less than 5% by weight, a sufficient scratch preventing effect may not be obtained. On the other hand, when the amount of the rubber fine particles is more than 30% by weight, sufficient releasability and lubricity may not be obtained.

In the case where the tire release agent is a tire outer surface release agent, for example, because a strong release property is required, it is better that the weight ratio of the rubber fine particles is relatively small. It is preferably 1 to 20% by weight, more preferably 2 to 15% by weight, and particularly preferably 3 to 10% by weight. When the amount of the rubber fine particles is less than 1% by weight, a sufficient scratch preventing effect may not be obtained. On the other hand, when the rubber fine particles are more than 20% by weight, the releasability may be deteriorated.
When producing a release agent for tires in the present invention, a rubber fine particle dispersion in which rubber fine particles are dispersed in water and stabilized in an emulsion, so-called rubber latex, is generally used as the rubber fine particles. Can do. In addition, it is preferable to use a rubber latex when producing a release agent for a tire because a release agent solution that is easy to handle and excellent in stationary stability can be obtained.

[Sulfur powder]
Sulfur powder has a component that exhibits an effect of preventing scratches generated on the tire surface when used together with rubber fine particles.
When sulfur is classified according to its production method, there are powdered sulfur, sulfur white, precipitated sulfur, colloidal sulfur, insoluble sulfur and the like. The sulfur powder used in the present invention may be any type of sulfur, and is not particularly limited. However, when it is colloidal sulfur that has a slow sedimentation rate when dispersed in water, it is liquid when the release agent is liquid. Among them, the sedimentation rate is slow and the stationary stability is excellent, which is preferable. Moreover, when manufacturing the mold release agent for tires by this invention, when the ease of handling of sulfur powder is considered, what disperse | distributed sulfur powder in water, ethylene glycol, etc., what is called aqueous sulfur should be used.

There is no limitation in particular about the average particle diameter of sulfur powder, Preferably it is 1-100 micrometers, More preferably, it is 1.2-90 micrometers, More preferably, it is 1.5-85 micrometers. If the average particle size of the sulfur powder is smaller than 1 μm, the releasability may be deteriorated. On the other hand, when the average particle diameter of the sulfur powder is larger than 100 μm, a sufficient effect for preventing scratches may not be obtained, and the tire may be colored yellow to deteriorate the appearance of the tire.
The weight ratio of the sulfur powder is preferably 1 to 25% by weight, more preferably 1.5 to 15% by weight, and particularly preferably 2.0 to 10.0% by weight with respect to the total amount of the three components. When the sulfur powder is less than 1% by weight, a sufficient effect for preventing scratches may not be obtained. On the other hand, if the sulfur powder is more than 25% by weight, sufficient releasability may not be obtained, and it may be colored yellow to deteriorate the aesthetic appearance of the tire.

As explained above, the required properties required for the sulfur powder are not exactly the same in the release agent for the inner surface and the release agent for the outer surface, and the preferable range of the weight ratio of the sulfur powder is different as follows. is there.
In the case where the release agent for tire is a release agent for tire inner surface, for example, because the tire product is likely to be scratched, it is better that the weight ratio of the sulfur powder is relatively large. 5 to 25% by weight is preferable, 6 to 24% by weight is more preferable, and 7 to 23% by weight is particularly preferable. If the sulfur powder is less than 5% by weight, sufficient scratch resistance may not be obtained. On the other hand, when there is more sulfur powder than 25 weight%, it may be colored yellow and the aesthetics of a tire may be deteriorated.

  In the case where the tire release agent is a tire outer surface release agent, for example, it is preferable that the weight ratio of the sulfur powder is relatively small for the reason of avoiding deterioration of the appearance due to excessive sulfur powder. The content is preferably 1 to 15% by weight, more preferably 3 to 10% by weight, and particularly preferably 4 to 8% by weight. If the sulfur powder is less than 1% by weight, sufficient scratch resistance may not be obtained. On the other hand, when there is more sulfur powder than 15 weight%, it may color yellow and the aesthetics of a tire may be deteriorated.

〔solvent〕
The mold release agent for tires of the present invention may contain a solvent. By including a solvent in the tire release agent, the tire release agent can be handled as a fluid, the workability during use is improved, and adhesion that does not want to occur when attaching the tire release agent Unevenness can be prevented.
Although there is no limitation in particular about the weight ratio of a solvent, 35 to 99 weight% of the whole tire mold release agent is preferable, 50 to 98.5 weight% is further more preferable, 60 to 98 weight% is especially preferable. When the amount of the solvent is less than 35% by weight, the viscosity of the release agent for tires becomes high, and even if it is attached using a sprayer or the like, a uniform adhesion surface cannot be obtained, and sufficient release agent performance cannot be obtained. There is. On the other hand, if the amount of the solvent is more than 99% by weight, it takes time for the tire release agent to dry, and tire production efficiency may deteriorate.

As explained above, the inner surface release agent and the outer surface release agent do not have exactly the same required characteristics (for example, characteristics such as viscosity adjustment of the release agent) for the solvent, and the weight ratio of the solvent There are also differences in the preferred range as follows.
In the case where the tire release agent is a tire inner surface release agent, for example, it is preferable that the weight ratio of the solvent is small because it is necessary to dry in a relatively short time. 90 wt% is preferable, 55 to 85 wt% is more preferable, and 60 to 82 wt% is particularly preferable. When the amount of the solvent is less than 50% by weight, the viscosity becomes high and uniform adhesion may not be achieved. On the other hand, when the amount of the solvent is more than 90% by weight, it may take time to dry after adhesion, and the production efficiency may deteriorate.

In the case where the release agent for tires is a release agent for tire outer surfaces, for example, it is preferable that the solvent has a relatively high weight ratio because it is preferable to attach a low-viscosity release agent. 85 to 99% by weight of the total agent is preferable, 90 to 98.5% by weight is more preferable, and 95 to 98% by weight is particularly preferable. When the amount of the solvent is less than 85% by weight, the viscosity becomes high and it may be difficult to deposit uniformly. On the other hand, when the amount of the solvent is more than 98% by weight, it may take time for drying after adhesion, and the production efficiency may deteriorate.
There is no limitation in particular as a solvent, For example, water; Water-soluble organic solvents, such as methanol, ethanol, isopropyl alcohol, etc. can be mentioned. Among these solvents, water is preferable because it is inexpensive and safest and does not cause a problem of swelling of rubber fine particles. When a water-soluble organic solvent having a low boiling point, such as methanol or ethanol, is used as the solvent, the drying time after the tire release agent is adhered can be shortened.

[Inorganic powder]
The mold release agent for tires of the present invention may contain inorganic powder. When the tire release agent is a tire inner surface release agent, it is preferable to impart smoothness and air permeability between the raw tire and the bladder.
The polymerization ratio of the inorganic powder is not particularly limited, but is preferably 20 to 80% by weight, more preferably 25 to 78% by weight, and particularly preferably 30 to 75% by weight with respect to the total amount of the three components. If the polymerization ratio of the inorganic powder is less than 20% by weight, sufficient smoothness and air permeability may not be obtained. On the other hand, when the weight ratio of the inorganic powder is more than 80% by weight, a part of the tire product may become white and the appearance may deteriorate.

Although there is no limitation in particular about the average particle diameter of inorganic powder, 1-30 micrometers is preferable, 2-20 micrometers is more preferable, and 5-15 micrometers is the most preferable. If the average particle size of the inorganic powder is too small, air permeability may deteriorate. On the other hand, if the average particle size of the inorganic powder is too large, the tire product may be partly white and the appearance may deteriorate.
The inorganic component constituting the inorganic powder is not particularly limited. For example, montmorillonite, beidellite, nontronite, saponite, hectorite, soconite, stevensite, etc., smectite, bentonite, divermiculite, trivermiculite, etc. Vermiculite, Halloysite, Kaolinite, Enderite, Dickite, Nacrite, Chrysotile, etc. Kaolin, talc, pyrophyllite, mica (mascobite, sericite), margarite, clintonite, muscovite, biotite, phlogopite, synthetic Mica, fluoromica, paragolite, phlogopite, repidolite, tetrasilic mica, tenolite and other phyllosilicates, antigolite and other jamonite, donpasite, sudite, kukkaite, clinok A, chamosite, chlorite, chlorite such as nanlite, sepiolite, piolite such as palygorskite-paligoskite, (heavy or light) calcium carbonate, magnesium carbonate, barium carbonate, carbonate, calcium sulfate, barium sulfate, etc. Metal oxides such as sulfate, silica, alumina, magnesium oxide, antimony trioxide, titanium oxide, iron oxide, metal hydroxides such as aluminum hydroxide, magnesium hydroxide, iron hydroxide, bengara, diatomaceous earth, aluminum silicate, Examples thereof include carbon black and graphite. These components may be used alone or in combination of two or more.

[Surfactant]
The mold release agent for tires of the present invention may contain a surfactant. When the release agent for tire contains a surfactant, the release agent for tire can be uniformly attached. In addition, when the tire release agent contains an inorganic powder together with a surfactant, the inorganic powder can be uniformly dispersed, and the dispersion stability is improved. Moreover, various physical properties such as wettability to the green tire and dispersibility of the inorganic powder can be adjusted by appropriately adjusting the weight ratio of the surfactant.
The surfactant may be at least one selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant, but the dispersion stability and wettability are increased synergistically. Therefore, it is desirable to use two or more kinds in combination. Particularly preferred is a combined system of a nonionic surfactant and an anionic surfactant.

The nonionic surfactant is not particularly limited, but a polyoxyalkylene type such as polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether (alkyl may be any one of 1 to 3) is desirable. A nonionic surfactant may use together 1 type (s) or 2 or more types.
The anionic surfactant is not particularly limited. For example, a carboxylic acid type anionic surfactant, a sulfonic acid type anionic surfactant, and the like are suitable. Monocarboxylates, polyoxyethylene alkyl ether carboxylates and the like are particularly suitable. As the sulfonic acid type anionic surfactant, alkane sulfonate, alkylbenzene sulfonate, dialkyl sulfosuccinate and the like are particularly suitable. These anionic surfactants may be used alone or in combination of two or more.
The release agent for tires of the present invention may further contain additives such as thickeners, antifoaming agents, preservatives and the like.

[Tire release agent and manufacturing method thereof]
About the manufacturing method of the mold release agent for tires of the present invention, as long as it includes a step of mixing the silicone component, the rubber fine particles and the sulfur powder, there is no particular limitation on the mixing order, the mixing equipment to be used, etc. Is contained in the mold release agent for tires, it is preferable to use a mixing facility such as a high-speed shear stirrer in order to improve the dispersion state of each component such as the three components.

[Tire and its manufacturing method]
The tire of the present invention is a tire obtained by attaching and vulcanizing the tire release agent described above to the inner surface and / or outer surface of a raw tire.
The tire manufacturing method of the present invention includes the above described tire release agent interposed between a raw tire and a bladder and / or between a raw tire and a mold, and the bladder is heated and expanded to form a raw tire. It is a manufacturing method including a vulcanization step of press-fitting into a mold and vulcanization molding.

First, necessary components such as bead wires and tire cords are combined mainly with unvulcanized rubber, and these are bonded together to prepare a tire original form called a raw tire.
Next, the release agent for tire of the present invention is interposed between the green tire and the bladder and / or between the green tire and the mold.

For example, first of all, a step of attaching the tire release agent of the present invention to the inner surface and / or the outer surface of the green tire is performed. Here, in order to adhere to the outer surface of the raw tire, a release agent for the tire may be attached to the inner surface of the mold corresponding to the outer surface of the raw tire, and the inner surface of the raw tire may be attached to the inner surface of the raw tire. A tire mold release agent may be attached to the inner surface of the bladder corresponding to the above.
The tire release agent is generally attached by spraying with an air gun or an airless gun, but may be applied with a brush or a centrifugal coater. The adhesion amount of the release agent for tires varies depending on the use and size of the tire product, and is not particularly limited. The adhesion amount of the release agent for tires is preferably 10 to 50 g / m ² in terms of weight after drying in the case of release agents for tire inner surfaces, and 1 to 5 g / m in the case of release agents for tire outer surfaces. ² is preferable. When the adhesion amount of the release agent for tires is small, sufficient release agent performance cannot be obtained. On the other hand, when there is too much adhesion amount, there are many mold release agent components for tires, and it may remain on a tire product and become dirty. Thereafter, when the adhered release agent for tire is sufficiently dried, it is allowed to stand at room temperature for several days if it is several tens of minutes to long.

As the next step of interposing the mold release agent for tires of the present invention between the green tire and the bladder and / or between the green tire and the mold, the dried green tire obtained above is placed in a metal mold. Install and place a rubber bag called bladder from the inside. Then, the bladder is heated and expanded with steam or the like at a high temperature. By the thermal expansion of the bladder, the raw tire is pressed against the mold and press-fitted, and vulcanization molding is performed so as to obtain a final tire shape, tread pattern, and the like.
There are no particular limitations on the bladder surface temperature (mold temperature), pressure, vulcanization time, etc. during vulcanization, but the surface temperature (mold temperature) is preferably 160 to 190 ° C., and the pressure is preferably 1 to 3 MPa. The vulcanization time is preferably 10 to 60 minutes. Thereafter, the internal pressure of the bladder is lowered and contracted, and then removed, and the vulcanized tire is removed from the vulcanizer. Thereafter, the tire product is inspected for abnormalities.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to these examples. Hereinafter, “part” means “part by weight”, and “%” means “% by weight”.

[Example 1]

(Tire release agent)
The raw material was blended with 63.9 parts of water and stirred with a high-speed shear stirrer to obtain a release agent for the tire inner surface having the composition shown in Table 1.
In Table 1, it is indicated as 6.0 parts of dimethylpolysiloxane, but actually, an oil-in-water emulsion 20 containing dimethylpolysiloxane (concentration 30.0%) and an emulsifier (concentration 5%). 0 parts were used. In Table 1, 2.5 parts of natural rubber fine particles are shown, but in practice, 5.0 parts of natural rubber latex liquid (product name: Residex MG-40S) containing 50% of rubber fine particles is added. Using. Since these two raw materials contain water, the amount of water actually contained in this tire inner surface release agent was 79.4 parts.

Even when producing a mold release agent for tires in the following examples and comparative examples, the dimethylpolysiloxane, alkyl group-modified silicone, IR rubber fine particles and natural rubber fine particles shown in Tables 1 and 2 contain these. In addition, an emulsion or latex that may contain other components such as an emulsifier and water was used (see footnote in the table). When these raw materials are used, the amounts shown in Table 1 and Table 2 are the amounts of dimethylpolysiloxane, alkyl group-modified silicone, IR rubber fine particles and natural rubber fine particles themselves, and other components such as emulsifiers and water are included. It is not the amount to include.
About this mold release agent for tire inner surfaces, evaluation using the rubber specimen shown below and evaluation by tire manufacture were performed, and mold release property and aesthetics were evaluated.

(Evaluation using rubber specimen)
As shown in FIG. 1, a 4 cm × 3.5 cm × 0.5 cm unvulcanized rubber sheet B is superimposed on a 4 cm × 7 cm × 0.5 cm unvulcanized rubber sheet A to evaluate an unvulcanized rubber for evaluation. It was created. First, as shown in FIG. 2, a release agent for the tire inner surface was attached to only the upper surface with a sprayer so that the weight after drying was 15 g / square meter. Next, a 4 cm × 7 cm × 0.5 cm bladder rubber sheet is overlaid on the unvulcanized rubber for evaluation, set in a desktop test press machine, and vulcanized by pressing at 180 ° C. and 20 kg / square centimeter for 20 minutes. A vulcanized evaluation rubber as shown in FIG. 3 was obtained. After completion of vulcanization, release properties and aesthetics were evaluated. The evaluation criteria are as follows. As a result of the evaluation, as shown in Table 1, there was no problem in releasability, and the aesthetic appearance was also good.

1. Release property The vulcanized evaluation rubber and the bladder rubber sheet were peeled off at 90 degrees, and the release load required at that time was measured with a tensile tester to evaluate the release property. The evaluation criteria for releasability are as follows. In addition, when it has already peeled at the end of vulcanization, a tensile test cannot be performed, but it is evaluated as ◎ because it is excellent in releasability.
A: Peeling with a tensile load of less than 0.5N.
○: Peeling with a tensile load of 0.5N or more and 1.5N or less.
X: Peeling with a tensile load of 1.5 N or more.

2. Appearance Observe the surface of the vulcanized evaluation rubber and evaluate whether there are any scratches.
A: There is no scratch that can be visually confirmed.
○: Although there is a scratch, the scratch does not spread even if the rubber is bent 90 degrees in the opposite direction.
X: There are scratches that spread when the rubber is bent.

(Evaluation by tire manufacturing)
The release agent obtained above was adhered to the inner surface of a 215 / 60R16 size raw tire so that the adhesion amount after drying was 15 g / m ² . Next, 10 tires with the release agent adhered thereto were vulcanized by pressurizing at a mold temperature of 165 ° C. and a pressure of 20 kg / cm ² for 10 minutes. After completion of vulcanization, release properties and aesthetics were evaluated. The evaluation criteria are as follows. The evaluation results are shown in Table 1. There was no problem in releasability and the aesthetic appearance was also good.

1. Releaseability When the bladder is released from the vulcanized tire, releaseability is evaluated visually.
A: Release easily.
○: The mold is released, but the tire is temporarily deformed.
X: The mold is released, but the tire is deformed.

2. Appearance Observe the inside surface of the vulcanized tire and evaluate whether there is any scratch.
A: There is no scratch that can be visually confirmed.
○: Although there are scratches that can be visually confirmed, there is no effect on the tire performance.
X: There is a scratch that affects the tire performance.

[Examples 2 to 6 and Comparative Examples 1 to 4]
In each of Examples 2 to 6 and Comparative Examples 1 to 4, 63.9 parts of water used in Example 1 were changed to appropriate amounts, the respective raw materials were blended, and stirred with a high-speed shear stirrer. Or the release agent for tire inner surfaces shown in 2 was obtained.
The obtained tire inner surface release agent was evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Example 7
(Tire release agent)
The raw material was blended with 94.2 parts of water and stirred with a high-speed shear stirrer to obtain a release agent for the tire outer surface having the composition shown in Table 1.
About this mold release agent for tire outer surfaces, evaluation using the rubber specimen shown below and evaluation by tire manufacture were performed, and mold release property and aesthetics were evaluated.

(Evaluation using rubber specimen)
In the same manner as the evaluation using the rubber specimen shown in Example 1, a release agent for the tire outer surface was attached to the unvulcanized rubber for evaluation with a sprayer so that the weight after drying was 2 g / square meter. . Next, a 4 cm × 7 cm × 0.2 cm steel plate is overlaid on the unvulcanized rubber for evaluation, set in a desktop test press machine, pressurized at 180 ° C. and 20 kg / square centimeter for 20 minutes, vulcanized, and vulcanized. Sulfurized evaluation rubber was obtained. After completion of vulcanization, release properties and aesthetics were evaluated. The evaluation results are shown in Table 1.

1. Releasability The vulcanized evaluation rubber and the steel plate were peeled off at 90 degrees, and the peeling load required at that time was measured with a tensile tester to evaluate the releasability. The evaluation criteria for releasability are as follows. In addition, when it has already peeled at the end of vulcanization, a tensile test cannot be performed, but it is evaluated as ◎ because it is excellent in releasability.
A: Peeling with a tensile load of less than 0.5N.
○: Peeling with a tensile load of 0.5N or more and 1.5N or less.
X: Peeling with a tensile load of 1.5 N or more.

2. Appearance Observe the surface of the vulcanized evaluation rubber and evaluate whether there are any scratches.
A: There is no scratch that can be visually confirmed.
○: Although there is a scratch, the scratch does not spread even if the rubber is bent 90 degrees in the opposite direction.
X: There are scratches that spread when the rubber is bent.

(Evaluation by tire manufacturing)
The release agent obtained above was adhered to the outer surface of a 215 / 60R16 size raw tire so that the adhesion amount after drying was 2 g / m ² . Next, 10 tires with the release agent adhered thereto were vulcanized by pressurizing at a mold temperature of 165 ° C. and a pressure of 20 kg / cm ² for 10 minutes. After completion of vulcanization, release properties and aesthetics were evaluated. The evaluation criteria are as follows. The evaluation results are shown in Table 1.

1. Releasability When the vulcanized tire is released from the mold, the releasability is evaluated visually.
A: Release easily.
○: There is partial adhesion, but release.
X: It adheres partially and rubber | gum is damaged.

2. Appearance Observe the outer surface of the vulcanized tire and evaluate if there are any scratches.
A: There is no scratch that can be visually confirmed.
○: Although there are scratches that can be visually confirmed, there is no effect on the tire performance.
X: There are one or more scratches that affect the tire performance.

[Examples 8 to 9 and Comparative Examples 5 to 6]
In each of Examples 8 to 9 and Comparative Examples 5 to 6, 94.2 parts of water used in Example 7 were changed to appropriate amounts, respectively, and the raw materials were respectively mixed, and stirred with a high-speed shear stirrer. Or the mold release agent for tire outer surfaces shown in 2 was obtained.
The obtained tire outer surface release agent was evaluated in the same manner as in Example 7, and the results are shown in Tables 1 and 2.

(Table footnote)
Dimethylpolysiloxane: Water containing dimethylpolysiloxane (base oil viscosity at 25 ° C. 1,000 mPa · s; concentration 30.0%) and sodium polyoxyethylene dodecyl ether sulfate (concentration 5%) as emulsifier Oil droplet type emulsion Alkyl group-modified silicone: Alkyl group silicone (base oil viscosity at 25 ° C .: 500 mPa · s; concentration: 50.0%), sodium polyoxyethylene dodecyl ether sulfate (concentration: 5%) as an emulsifier Oil-in-water emulsion containing water Thickener: Xanthan gum powder IR rubber fine particles: IR rubber latex liquid with an average particle diameter of 1.5 μm and a rubber fine particle content of 65% (product name: Sepolex IR100)
Natural rubber fine particles: Natural rubber latex liquid with an average particle size of 1 μm and a content of rubber fine particles of 50% (product name: REGI-TEX MG-40S)
Antifoam: Mineral oil antifoam Preservative: Thiazoline preservative

1 Rubber sheet A
2 Rubber sheet B

Claims (2)

A mold release agent for a tire comprising a silicone component, rubber fine particles and sulfur powder ,
The weight ratio of the silicone component is 40 to 98% by weight, the weight ratio of the rubber fine particles is 1 to 30% by weight, and the weight ratio of the sulfur powder is 1 with respect to the total amount of the silicone component, rubber fine particles and sulfur powder. The mold release agent for tires which is -25 weight%, the average particle diameter of the said rubber fine particle is 0.1-100 micrometers, and the average particle diameter of the said sulfur powder is 1-100 micrometers . The tire release agent according to claim 1 is interposed between the raw tire and the bladder and / or between the raw tire and the mold, and the bladder is heated and expanded to press-fit the raw tire into the mold, A tire manufacturing method including a vulcanization step of vulcanization molding.

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