JP5802525B2 - Release agent for tire inner surface and tire manufacturing method using the same - Google Patents

Description

  The present invention relates to a mold release agent for a tire inner surface and a tire manufacturing method using the same. More specifically, the present invention relates to a mold release agent for a tire inner surface that exhibits a mold release action by being interposed between a tire and a bladder during tire vulcanization molding, and a method of manufacturing a tire using the same.

In the tire manufacturing process, vulcanization molding of an unvulcanized green tire is usually performed by inflating a rubber bag called a bladder with hot water or steam inside the green tire and press-molding the unvulcanized green tire into a 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 referred to as the inner surface of the raw tire). The release agent for the inner surface of the tire mainly has a performance (smoothness) that gives good lubricity between the inner surface of the raw tire and the outer surface of the bladder, and escapes air that has entered the outer surface of the bladder and the inner surface of the raw tire. A performance (air permeability) is required to bring them into close contact with each other, and when the bladder is contracted after the vulcanization is completed, a performance (releasability) is required that allows the outer surface of the bladder and the inner surface of the green tire to be smoothly peeled off. 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.
Patent Document 1 discloses that a composition of an aqueous silicone emulsion and an inorganic powder containing mica having a primary average particle size of 55 to 95 μm is used as a release agent for the tire inner surface. In this example, it is necessary to apply a release agent for the tire inner surface to each inner surface of the green tire to be vulcanized every time vulcanization is performed, and the working efficiency is low.

  In Patent Document 2, in order to increase the number of molding vulcanization times of the tire by the same bladder, the bladder and the silicone system are used together with the silicone mold release agent composition for the purpose of enhancing the peelability between the inner surface of the green tire and the outer surface of the bladder. The use of a primer treatment agent for improving the adhesion to the mold release agent composition is described. Depending on the combination of the release agent composition and the primer treatment agent, an improvement in release properties after several molding vulcanizations of the tire with the same bladder is recognized to some extent. However, in the method of Patent Document 2, it is necessary to first attach two drugs, which requires a little work.

JP 2005-193448 A JP-A-61-215015

  The problem to be solved by the present invention is to provide a release agent for the inner surface of a tire that maintains excellent releasability even when used multiple times for vulcanization molding of a raw tire, and a method for producing a tire using the same. It is.

As a result of intensive studies to solve the above-mentioned problems, the present inventors solved the conventional problems all at once by including a silicone-based nonionic surfactant having specific physical properties in the release agent for the tire inner surface. The present invention was reached.
The mold release agent for the tire inner surface according to the present invention includes an alkyl silicone, a silicone nonionic surfactant having a cloud point of 20 to 60 ° C. and a kinematic viscosity of 10 to 60 cSt (25 ° C.), and an inorganic component made of powder. A mold release agent for tire inner surface containing water.

It is preferable that the release agent for the tire inner surface according to the present invention satisfies at least one of the following requirements (1) to (4).
(1) The weight ratio of the silicone-based nonionic surfactant is 0.01 to 20% by weight with respect to the total amount of the alkylsilicone, the silicone-based nonionic surfactant, and the inorganic component.
(2) The weight ratio of the inorganic component is 2 to 40% by weight based on the total amount of the alkyl silicone, the silicone-based nonionic surfactant and the inorganic component.
(3) The critical micelle formation concentration (CMC) of the silicone-based nonionic surfactant is 1000 mg / L or less (25 ° C.), and the surface tension (γCMC) at the critical micelle formation concentration is 15 to 40 mN / m (25 ° C).
(4) The inorganic component is calcium carbonate.

In the tire manufacturing method according to the present invention, the tire inner surface release agent is applied to the inner surface of the raw tire and / or the outer surface of the bladder, the bladder is heated and expanded, and the raw tire is press-fitted into a mold. It is a manufacturing method including a first molding step for vulcanization molding, and a second molding step for heat-expanding the bladder, press-fitting another green tire into a mold, and vulcanization molding.
The second molding step is preferably performed at least three more times. Moreover, it is good to perform the said 2nd shaping | molding process, without apply | coating the mold release agent for tire inner surfaces to any of the inner surface of another raw tire, and the outer surface of the said bladder.
The tire according to the present invention is a tire obtained by adhering the release agent for a tire inner surface to the inner surface of a raw tire and vulcanizing the tire.

Even if the release agent for tire inner surface of the present invention is used a plurality of times for vulcanization molding of raw tires, excellent release properties are maintained.
In the tire manufacturing method of the present invention, since the release agent for the tire inner surface of the present invention is used, excellent mold releasability is maintained even when the raw tire is vulcanized and molded several times, and the tire productivity is high.

  Each component blended in the tire inner surface release agent of the present invention will be described, and then the tire inner surface release agent and the like will be described in detail.

[Alkyl silicone]
Alkyl silicone is a main component that imparts releasability and lubricity to the tire inner surface release agent. Alkyl silicone is a general term for organopolysiloxanes having at least one alkyl group, and may be in any form such as oil, rubber, and resin.
Examples of organopolysiloxanes having at least one alkyl group include dialkylpolysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, methylisopropylpolysiloxane, methyldodecylpolysiloxane; methylphenylpolysiloxane, dimethylsiloxane / methylphenylsiloxane Examples thereof include alkylphenyl polysiloxanes such as copolymers and dimethylsiloxane / diphenylsiloxane copolymers; alkylaralkyl polysiloxanes such as methyl (phenylethyl) polysiloxane and methyl (phenylpropyl) polysiloxane. These organopolysiloxanes may be used alone or in combination of two or more.

From the viewpoint of releasability, the alkyl silicone is preferably in the form of an oil having a linear molecular structure, a low degree of polymerization, and fluidity at room temperature. The viscosity is not particularly limited, but the kinematic viscosity at 25 ° C. is preferably from 100 to 500,000 cSt, more preferably from 300 to 100,000 cSt, from the viewpoint of the balance between releasability and product stability. In general, a Cannon-Fenske viscometer, an Ubbelohde viscometer, or the like is used to measure these kinematic viscosities, but it is difficult to measure a kinematic viscosity exceeding 100,000 cSt. Therefore, in this invention, kinematic viscosity is computed from the measured value and density of the viscosity with the viscometer demonstrated in an Example.
As the alkyl silicone, an emulsion of alkyl silicone may be used in the production of the release agent for the tire inner surface, and the emulsion is preferably an oil-in-water emulsion.

[Silicone-based nonionic surfactant]
Silicone nonionic surfactants have nonionic groups such as polyoxyalkylene groups (polyether groups) in addition to siloxane bonds in their molecules, and have an affinity for the inner surface of raw tires and the outer surface of bladders. It is an excellent component. Therefore, when the release agent for the tire inner surface is applied to the inner surface of the raw tire, the silicone-based nonionic surfactant is a component obtained by removing water from the release agent for the tire inner surface (hereinafter referred to simply as “release agent”). It is sometimes referred to as a “constituent component”.) Is effectively transferred to the outer surface of the bladder during vulcanization molding of the raw tire and exerts its action. In addition, when the release agent for the tire inner surface is applied to the outer surface of the bladder, the silicone-based nonionic surfactant exerts the action by effectively bringing the components of the release agent into close contact with the outer surface. As a result, the mold release agent for tire inner surface of the present invention maintains excellent mold release properties even when used multiple times for vulcanization molding of raw tires.
When the release agent for the tire inner surface is applied to the inner surface of the green tire, the constituent components of the release agent are effectively transferred to the outer surface of the bladder, for example, as follows. The inner surface of the green tire and the outer surface of the bladder are usually made of the same or similar rubber such as butyl rubber. However, the degree of smoothness of the surface is more complicated on the outer surface of the bladder because of the greater undulations on the surface. On the other hand, silicone surfactants have a high affinity for rubber and alkyl silicones and are excellent in penetrability. Therefore, when the inner surface of the green tire and the outer surface of the bladder are in close contact during vulcanization molding of the green tire, the components of the mold release agent penetrate into the outer surface of the bladder with large undulations, and use the complicated surface state of the outer surface of the bladder And can be firmly fixed. Therefore, after the first molding step described later, the constituent components of the release agent are transferred onto the outer surface of the bladder.

Silicone-based nonionic surfactants not only sufficiently disperse inorganic components and alkyl silicones in water to improve the dispersion stability of the release agent for the tire inner surface, but also apply the release agent for the tire inner surface to a spray device, etc. Thus, when applied to the inner surface of the raw tire, it is a component that can adjust the characteristic (wetting property) of preventing liquid repellency by adjusting the blending amount.
The cloud point of a silicone type nonionic surfactant is 20-20 degreeC normally, Preferably it is 25-55 degreeC, More preferably, it is 30-50 degreeC. If the cloud point is too low or too high, the component of the release agent may not be transferred or adhered sufficiently. The cloud point measurement method will be described in detail below.

The kinematic viscosity at 25 ° C. of the silicone-based nonionic surfactant is usually 10 to 60 cSt, preferably 25 to 55 cSt, and more preferably 30 to 50 cSt. When the kinematic viscosity is too low, the storage stability of the release agent for the tire inner surface is lowered. On the other hand, when the kinematic viscosity is too high, liquid repelling occurs on the inner surface of the green tire and the outer surface of the bladder when the release agent for the inner surface of the tire is applied.
The critical micelle formation concentration (CMC) at 25 ° C. of the silicone-based nonionic surfactant is preferably 1000 mg / L or less, more preferably 1 to 1000 mg / L, and particularly preferably 10 to 200 mg / L. Further, the surface tension (γCMC) measured at 25 ° C. at the critical micelle formation concentration is preferably 15 to 40 mN / m, more preferably 20 to 35 mN / m. If CMC or γCMC is too small, the rubber may penetrate between the rubbers constituting the inner surface of the raw tire and the tire strength may be reduced. On the other hand, if CMC or γCMC is too large, when it adheres to the inner surface of the raw tire or the outer surface of the bladder, repelling may occur and the tire inner surface release agent may not be uniformly adhered.

Silicone-based nonionic surfactants are organopolysiloxanes having at least one oxyalkylene group in the molecule. Here, the oxyalkylene group is not particularly limited, but is a group represented by — (OA) _n — (A is preferably an alkylene group having 1 to 4 carbon atoms; n is preferably 1 to 40). Can be mentioned. Here, the carbon number of the alkylene group is more preferably 1 to 3, particularly preferably 2 to 3. When the number of carbon atoms of the alkylene group exceeds 4, the hydrophilicity is lowered and it becomes difficult to apply the release agent for the tire inner surface. N is more preferably 4 to 30, and particularly preferably 5 to 20. When n exceeds 40, the viscosity increases and it may take time to dissolve in water.
The number of silicon atoms contained in the molecule of the silicone-based nonionic surfactant is not particularly limited, but is preferably 10 or less, more preferably 1 to 6, particularly preferably 2 to 5, and most preferably 3 to 3. 4. When the number of silicon atoms exceeds 10, the silicone-based nonionic surfactant has a high viscosity, is difficult to dissolve in water, and it becomes difficult to produce a release agent for the tire inner surface.

Although there is no limitation in particular about the molecular weight of a silicone type nonionic surfactant, Preferably it is 100-1000, More preferably, it is 150-900, Most preferably, it is 200-800. When the molecular weight of the silicone-based nonionic surfactant is less than 100, the hydrophilicity is lowered, and it becomes difficult to apply the release agent for the tire inner surface. On the other hand, when the molecular weight of the silicone-based nonionic surfactant exceeds 1000, the viscosity increases, and it takes time to dissolve in water, making it difficult to produce a release agent for the tire inner surface.
As the silicone-based nonionic surfactant, for example, a nonionic surfactant represented by the following chemical formula (1) is preferable.

(Wherein R is a hydrogen atom or an alkyl group (preferably having 1 to 7 carbon atoms); m is preferably 1 to 40; p is preferably 1 to 7; and A ^{1 to} A ³ are the same or different from each other. It may be a monovalent organic group.)
In the chemical formula (1), R is preferably a hydrogen atom. Moreover, when R is an alkyl group, the carbon number thereof is more preferably 1 to 5, particularly preferably 1 to 3. If the alkyl group has more than 7 carbon atoms, water solubility is lowered, and it becomes difficult to apply a release agent for the tire inner surface.
In the chemical formula (1), m is more preferably 4 to 30, particularly preferably 5 to 20. If m exceeds 40, the viscosity increases and it may take time to dissolve in water.

In the chemical formula (1), p is more preferably 1 to 5, particularly preferably 2 to 3. When p exceeds 7, hydrophilicity falls and it becomes difficult to apply | release the mold release agent for tire inner surfaces.
In the chemical formula (1), A ^{1 to} A ³ are not particularly limited as long as they are monovalent organic groups which may be the same or different from each other, but A ^{1 to} A ³ include —O—Si≡ and the like. An organosilicon group having a structure, an alkoxy group having 1 to 10 carbon atoms, an alkyl group, a phenoxy group, a phenyl group, an alkenyl group, and the like are preferable. The organosilicon group may be bonded to an alkoxy group having 1 to 10 carbon atoms, an alkyl group, a phenoxy group, a phenyl group, an alkenyl group, or the like, or may be bonded to another organosilicon group.

[Inorganic component consisting of powder]
An inorganic component made of powder (hereinafter sometimes simply referred to as “inorganic component”) is a component mainly used to impart smoothness and air permeability.
Examples of inorganic components include, but are not limited to, smectites such as montmorillonite, beidellite, nontronite, saponite, hectorite, saconite, and stevensite; bentonite; vermiculite such as divermiculite and trivermiculite; halloysite, kaolinite Kaolin such as enderite, dickite, nacrite, chrysotile; talc, pyrophyllite, mica (mascobite, sericite), margarite, clintonite, muscovite, biotite, phlogopite, synthetic mica, fluoromica, paragolite , Phlogopite, repidolite, tetrasilic mica, teniolite and other phyllosilicates; antigolite and other jamon stones; donpasite, sudite, kukkaite, clinochlore, chamosite Chlorite, chlorite, such as nanlite; Sepiolite, Piolite-palyskite, such as palygorskite; (heavy) carbonates such as calcium carbonate, magnesium carbonate, barium carbonate; sulfates such as calcium sulfate, barium sulfate; silica, alumina, Metal oxides such as magnesium oxide, antimony trioxide, titanium oxide and iron oxide; metal hydroxides such as aluminum hydroxide, magnesium hydroxide and iron hydroxide; Bengala; diatomaceous earth; aluminum silicate; carbon black; be able to. These components may be used alone or in combination of two or more.

If the inorganic component is calcium carbonate, when manufacturing a tire using a release agent for the inner surface of the tire, the air permeability is excellent, and the inorganic component that is a component of the release agent easily transfers and adheres. preferable.
Although there is no limitation in particular about the average primary particle diameter of an inorganic component, 1-30 micrometers is preferable and 15-25 micrometers is more preferable. When the average primary particle size of the inorganic component is smaller than 1 μm,
When preparing the mold release agent for the tire inner surface, poor dispersion of the inorganic powder and insufficient air permeability may occur during tire vulcanization. On the other hand, when the average primary particle size of the inorganic component is larger than 30 μm, smoothness may be insufficient during tire vulcanization.

〔water〕
Water is an important component for uniformly dispersing the inorganic component contained in the tire inner surface release agent and for uniformly attaching the tire inner surface release agent. The water may be any of distilled water, ion exchange water, tap water, industrial water, ground water, river water, well water, and the like.

[Other ingredients]
In addition to the components described above, the release agent for the tire inner surface of the present invention may include a surfactant other than the silicone-based nonionic surfactant (hereinafter sometimes referred to as other surfactant), carboxy as necessary. Additives such as thickeners such as sodium methylcellulose, antifoaming agents and preservatives may be blended.
Other surfactants are preferably used for adjusting the wettability as in the case of the silicone-based nonionic surfactant. The other surfactant may be any of nonionic surfactants other than silicone-based nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants, but nonionic surfactants that are not silicone-based, Anionic surfactants are preferred.

Non-ionic surfactants that are not silicone-based include polyoxyalkylene group-containing non-ionic interfaces such as polyoxyethylene alkyl ether and polyoxyethylene polyoxypropylene alkyl ether (wherein alkyl may be any one of 1 to 3). An activator is desirable. Nonionic silicone nonionic surfactants may be used alone or in combination of two or more.
As the anionic surfactant, a carboxylic acid anionic surfactant, a sulfonic acid anionic surfactant, and the like are suitable. For the carboxylic acid anionic surfactant, a polyoxyethylene alkyl ether carboxylate is particularly suitable. Yes. As the sulfonic acid anionic surfactant, alkane sulfonate, alkylbenzene sulfonate, dioctyl sulfosuccinate and the like are particularly suitable. These anionic surfactants may be used alone or in combination of two or more.

  When other surfactants to be used include non-ionic surfactants and anionic surfactants that are not silicone-based, there is no particular limitation on the respective weight ratios, but there is an effect on foaming and the dispersion stability of inorganic components. For this reason, the nonionic surfactant / anionic surfactant (weight ratio) that is not silicone-based is preferably 75/25 to 99/1, more preferably 85/15 to 98/2, and 90/10. It is especially preferable that it is -95/5.

[Releasing agent for tire inner surface and manufacturing method thereof]
The mold release agent for a tire inner surface of the present invention contains the alkyl silicone, the silicone-based nonionic surfactant, the inorganic component, and water described above as essential. The mold release agent for the tire inner surface may further contain other components described above.
The weight ratio of alkyl silicone, silicone-based nonionic surfactant, inorganic component and water contained in the release agent for the tire inner surface is not particularly limited, but may be a blending ratio described below. Hereinafter, the alkyl silicone, the silicone-based nonionic surfactant, and the inorganic component may be simply referred to as “three components”.

The weight ratio of the total amount of the three components is preferably 10 to 80% by weight, more preferably 20 to 70% by weight, and particularly preferably 30 to 60% by weight based on the entire mold release agent for the tire inner surface. If the weight ratio of the total amount of the three components is less than 10% by weight, it takes time for the moisture to dry after applying the tire inner surface release agent, and tire production efficiency may deteriorate. On the other hand, when the weight ratio of the total amount of the three components exceeds 80% by weight, the viscosity becomes high and it may be difficult to use the tire for manufacturing.
The weight ratio of the alkyl silicone is preferably 20 to 80% by weight, more preferably 25 to 70% by weight, and particularly preferably 30 to 60% by weight with respect to the total amount of the three components. When there are too few alkyl silicones, the transferability and adhesiveness of the component of a mold release agent, and the mold release property at the time of tire manufacture may become inadequate. On the other hand, when there are too many alkyl silicones, smoothness will deteriorate, the viscosity of a tire inner surface mold release agent may become high, the adhesion failure may arise, and it may become difficult to use for manufacture of a tire.

The weight ratio of the silicone-based nonionic surfactant is preferably 0.01 to 10% by weight, more preferably 0.05 to 7.5% by weight, particularly preferably 0.1%, based on the total amount of the three components. ~ 5% by weight. If the silicone-based nonionic surfactant is too little, when the tire inner surface release agent is applied to the inner surface of the raw tire or the outer surface of the bladder, liquid repellency may occur or the storage stability of the release agent for the tire inner surface may be reduced. It may decrease. On the other hand, when there are too many silicone type nonionic surfactants, smoothness will deteriorate and the application | coating defect by foaming of the mold release agent for tire inner surfaces may generate | occur | produce.
The weight ratio of the inorganic component is preferably 2 to 40% by weight, more preferably 5 to 30% by weight, and particularly preferably 10 to 20% by weight with respect to the total amount of the three components. When there are too few inorganic components, smoothness may deteriorate. On the other hand, if there are too many inorganic components, the powder may fall off from the molded tire inner surface, and the periphery of the tire storage location may be soiled.

The weight ratio of water is not particularly limited, but is preferably 35 to 90% by weight, more preferably 40 to 70% by weight, and particularly preferably 45 to 60% by weight with respect to the entire release agent for the tire inner surface. is there. When there is too little water, the inorganic component contained in the release agent for the tire inner surface is not sufficiently dispersed, so that stability is lost and a defective tire may be generated. On the other hand, when there is too much water, time may be required for drying when the release agent for the tire inner surface is applied. Moreover, the weight ratio of the inorganic component contained in the mold release agent for the tire inner surface is lowered, and the mold release property may be lowered.
About the manufacturing method of the mold release agent for tire inner surfaces of this invention, if it includes the process of mixing an alkyl silicone, a silicone type nonionic surfactant, an inorganic component, and water, about mixing order, mixing equipment to be used, etc. There is no particular limitation.

[Tire manufacturing method]
The tire manufacturing method of the present invention is a manufacturing method including a first molding step and a second molding step, which will be described in detail below.
In the tire manufacturing method of the present invention, the second molding step may be further continued after the first molding step and the second molding step. The number of times that the second molding step is further performed is better from the viewpoint of improving the productivity of the tire, preferably at least one more time, more preferably at least another three times, particularly preferably at least another five times, most preferably. May be performed at least 10 times in succession.

In the first molding process, first, unvulcanized rubber is used as the main component, and the necessary members such as bead wires and tire cords are combined and bonded together. Prepare a rubber bag that can introduce the gas.
Next, the release agent for the tire inner surface of the present invention is applied to the inner surface of the green tire and / or the outer surface of the bladder, and adhered. The tire inner surface release agent may be applied to either the inner surface of the green tire or the outer surface of the bladder. If a coating apparatus for coating the inner surface of the raw tire is already installed, it is preferable because a new facility investment is not required and the release agent for the tire inner surface can be easily applied to the inner surface of the raw tire. On the other hand, in order to repeat the second molding step as many times as possible, it is preferable to securely adhere the release agent for the tire inner surface to the outer surface of the bladder without waste. In this case, apply the release agent for the tire inner surface to the outer surface of the bladder. It is preferable to do.

The tire inner surface release agent is generally sprayed with an air gun or an airless gun, but a brush or a centrifugal coater may be used. The adhesion amount of the release agent for the tire inner surface varies depending on the use and size of the obtained tire, but the amount per unit area of the component of the release agent after drying the release agent for the tire inner surface (applied after drying) It is preferable to adjust the adhesion amount of the release agent for the tire inner surface so that the amount) is 10 to 50 g / m ² . After applying the release agent for the inner surface of the tire, until the adhered release agent for the inner surface of the tire is sufficiently dried, if it is several tens of minutes to longer at room temperature, the raw tire and / or the bladder is left for several days. .
In the first molding step, after the application of the mold release agent for the tire inner surface and drying, the bladder is heated and expanded, the raw tire is press-fitted into a mold, and vulcanized to obtain a tire. The bladder is heated and expanded by pressurizing the inside with steam or the like at a high temperature. As a result, the raw tire is pressed against the mold, pressed into a final tire shape, tread pattern, and the like, and vulcanized to obtain a tire. The bladder surface temperature (mold temperature) during vulcanization is preferably 160 to 190 ° C., the pressure is preferably 12 to 30 kg / cm ² , and the vulcanization time is preferably 10 to 60 minutes.

When the first molding step is completed, the release agent for the tire inner surface is applied to the inner surface of the raw tire with the silicone-based nonionic surfactant contained in the release agent for the tire inner surface. Ingredients can be effectively transferred to the outer surface of the bladder. Moreover, when the mold release agent for tire inner surfaces is apply | coated to the outer surface of a bladder, the structural component of a mold release agent can be closely stuck to an outer surface. In any case, when the first molding step is completed, the constituent components of the release agent are effectively in close contact with the outer surface of the bladder.
In the second molding step, a green tire is prepared separately and the bladder after the first molding step is used. In the second molding step, the bladder is heated and expanded, and another green tire is press-fitted into the mold and vulcanized. The conditions for the vulcanization molding are the same as the conditions for the first molding step described above.

In the second molding process, the bladder is heated and expanded by substantially applying the tire inner surface release agent to both the inner surface of the raw tire and the outer surface of the bladder, and another raw tire is made into a mold. It can be press-fitted and vulcanized. In this case, since the mold release agent for the tire inner surface of the present invention is used, excellent mold releasability is maintained even when used multiple times for vulcanization molding of a raw tire, and the productivity of the tire is increased.
Further, in the second molding step, a release agent for the tire inner surface may be applied to the inner surface of the separately prepared raw tire and / or the outer surface of the bladder. In that case, labor and time required for coating are required, but improvement in releasability can be expected. When applying the mold release agent for the tire inner surface in the second molding step, the component of the mold release agent is effectively in close contact with the outer surface of the bladder when the first molding step is completed. The amount of the release agent for the tire inner surface used in the process can be suppressed to be smaller than usual.

In the case of applying the tire inner surface release agent in the second molding step, the tire inner surface release agent to be used is not limited to the tire inner surface release agent of the present invention, and other tire inner surface release agents, etc. Also mentioned.
The tire of the present invention is a tire obtained by adhering the above-described mold release agent for the tire inner surface to the inner surface of the raw tire and vulcanizing it. The components of the release agent for the tire inner surface adhere to the outer surface of the bladder and do not remain on the inner surface of the resulting tire, so that the aesthetic appearance is improved and the slip with the wheel is reduced.

Examples of the present invention and comparative examples will be described in detail below, but the scope of the present invention is not limited to these examples. Hereinafter, “parts” means “parts by weight”.
The clouding point, kinematic viscosity and surface tension (γCMC) at the critical micelle formation concentration of the silicone-based nonionic surfactant and the physical properties of the release agent for the tire inner surface were evaluated by the following measurement methods.

[Cloud point of silicone-based nonionic surfactant]
1 g of sample, 94 g of pure water and 5 g of 2- (2-butoxyethoxy) ethanol were mixed to prepare a uniform liquid. Subsequently, this liquid was heated gradually, and the liquid temperature at the time when the liquid became cloudy after phase separation was defined as a cloud point (° C.).

[Kinematic viscosity of silicone-based nonionic surfactant]
Using a Brookfield viscometer (product name TVB-10, manufactured by Toki Sangyo Co., Ltd.), the viscosity of the silicone-based nonionic surfactant was measured at 25 ° C., and the numerical value (unit: mPa · s) was 25 ° C. The kinematic viscosity (unit: cSt) was obtained by dividing by the density (unit: g / mL).

[CMC and γCMC of silicone-based nonionic surfactant]
CMC and γCMC were measured at 25 ° C. using a Processor Tensiometer K100 manufactured by Cruz, Inc. by the Wilhelmy method.

[Physical properties of release agent for tire inner surface]
(Model experiment)
The tire inner surface release agent was applied to two unvulcanized tire inner surface rubber sheets (4 cm × 7 cm × 0.2 cm) so that the coating amount after drying was 15 g / m ² . Then, a bladder rubber sheet (3 cm × 3 cm × 0.5 cm) is overlaid on one coated unvulcanized tire inner rubber sheet, and a 500 g weight is placed on the rubber sheet and pulled horizontally at a speed of 10 cm / min. N) was measured and the smoothness was evaluated.
A bladder rubber sheet of the same size is superimposed on the coated surface of another unvulcanized tire inner surface rubber sheet coated with a mold release agent for the inner surface of the tire, set on a tabletop test press machine, mold temperature 180 ° C, Pressurization was performed at a pressure of 20 kg / cm ² for 20 minutes and vulcanized. The vulcanized rubber sheet was peeled off, and the state of peeling, the transfer of the constituents of the release agent to the bladder rubber sheet, the state of transfer and the like were observed.
Next, the surface of the release agent for the bladder rubber sheet obtained after peeling the vulcanized rubber sheet is transferred and transferred, and the unvulcanized tire to which the release agent for the tire inner surface is not applied The inner rubber sheet was overlaid, and vulcanization and peeling operations and observations were repeated as described above.

(Tire manufacturing experiment)
In the model experiment, the inner surface of an actual raw tire (215 / 60R16 size) is used instead of the unvulcanized tire inner rubber sheet, and the outer surface of the actual bladder is used instead of the bladder rubber sheet. Except for this, a tire was obtained in the same manner as the model experiment. At that time, the state of peeling when the bladder was peeled off from the inner surface of the tire, the transition of the constituents of the release agent to the bladder, the state of transfer and the like were observed.
Next, using a bladder obtained after peeling off from the inner surface of the tire and a raw tire not coated with a release agent for the tire inner surface, vulcanization and peeling operations and observations were repeated to produce a tire.

[Example 1]
(Preparation of release agent for tire inner surface)
An oil-in-water solution of 5 parts of 3- (polyoxyethylene) propylheptamethyltrisiloxane which is a silicone-based nonionic surfactant and alkyl silicone (KF412 manufactured by Shin-Etsu Chemical Co., Ltd .; kinematic viscosity 500 cSt) with respect to 18.8 parts of tap water 60 parts of a drop-type emulsion (alkyl silicone content: 50%) was uniformly mixed. Next, dimethylpolysiloxane oil-in-water emulsion (base oil kinematic viscosity: about 10,000 cSt, dimethylpolysiloxane content: 40%) 5 parts, light calcium carbonate powder ( Manufactured by Kamishima Chemical Co., Ltd .; 10 parts of average particle size 10 μm, sodium carboxymethylcellulose (1% aqueous solution viscosity at 25 ° C .: 10 mPa · s) 0.1 part, polyoxyethylene alkyl ether (Nippon Shokubai Softanol 70) 0 part and 0.1 part of sodium dodecylbenzenesulfonate were added, and the mixture was uniformly dissolved and dispersed using a homomixer to prepare mold release agent 1.
The physical properties of 3- (polyoxyethylene) propylheptamethyltrisiloxane were a cloud point of 45 ° C., a kinematic viscosity of 40 cSt, and γCMC of 21 mN / m at 25 ° C.

(Physical property evaluation of release agent for tire inner surface)
The physical properties were evaluated according to [Physical properties of release agent for tire inner surface] described above. The same applies to the physical property evaluation of the following examples and comparative examples.
When the release agent 1 was used, the tensile load was 1.5 N, and it was confirmed that sufficient smoothness was obtained.
When the vulcanized rubber sheet was peeled off, it was easily peeled off. In addition, it was confirmed that almost no components of the release agent remained on the peeled vulcanized rubber sheet, and almost all of the components of the release agent were transferred to the surface of the bladder rubber sheet and transferred. did.

Next, using this bladder rubber sheet and an unvulcanized tire inner surface rubber sheet to which no release agent for the inner surface of the tire is applied, the vulcanization and peeling operations are repeated four times to obtain four unvulcanized sheets. It was confirmed that the tire inner rubber sheet could be released. However, although the fifth vulcanization and peeling operation was performed, peeling was not possible.
The same results as above were obtained when a tire was produced from a green tire using the mold release agent 1. That is, it was confirmed that four tires could be manufactured in succession by repeating the vulcanization and peeling operations four times using a raw tire to which a release agent for the tire inner surface was not applied. However, although the fifth vulcanization and peeling operation was performed, the peeling was not possible and the fifth tire could not be manufactured.

[Example 2]
(Preparation of release agent for tire inner surface)
Example 1 except that 60 parts of the alkylsilicone oil-in-water emulsion and 5 parts of dimethylpolysiloxane oil-in-water emulsion are changed to 65 parts of dimethylpolysiloxane oil-in-water emulsion in Example 1. In the same manner as in Example 1, a release agent 2 was obtained.

(Physical property evaluation of release agent for tire inner surface)
When the release agent 2 was used, the tensile load was 2.0 N, and it was confirmed that sufficient smoothness was obtained.
When the vulcanized rubber sheet was peeled off, it was easily peeled off. In addition, it was confirmed that almost no components of the release agent remained on the peeled vulcanized rubber sheet, and almost all of the components of the release agent were transferred to the surface of the bladder rubber sheet and transferred. did.

Next, using this bladder rubber sheet and an unvulcanized tire inner surface rubber sheet not coated with a release agent for the inner surface of the tire, the vulcanization and peeling operations were repeated four times, and another four unvulcanized sheets were added. It was confirmed that the rubber tire inner rubber sheet could be released. However, although the fifth vulcanization and peeling operation was performed, peeling was not possible.
The same results as described above were obtained when a tire was produced from a green tire using the release agent 2. That is, it was confirmed that four tires could be manufactured in succession by repeating the vulcanization and peeling operations four times using a raw tire to which a release agent for the tire inner surface was not applied. However, although the fifth vulcanization and peeling operation was performed, the peeling was not possible and the fifth tire could not be manufactured.

Example 3
(Preparation of release agent for tire inner surface)
In Example 1, 10 parts of light calcium carbonate powder were mixed with 2 parts of mascobite mica powder (manufactured by Yamaguchi Mica; average particle size 40 μm) and talc (manufactured by Matsumura Sangyo Co., Ltd .; Crown Talc Pharmacopoeia PP; average particle size 11 μm) 8 A release agent 3 was obtained in the same manner as in Example 1 except that the release agent 3 was changed.

(Evaluation of release agent for tire inner surface)
When the release agent 3 was used, the tensile load was 1.4 N, and it was confirmed that sufficient smoothness was obtained.
When the vulcanized rubber sheet was peeled off, it was easily peeled off. In addition, it was confirmed that almost no components of the release agent remained on the peeled vulcanized rubber sheet, and almost all of the components of the release agent were transferred to the surface of the bladder rubber sheet and transferred. did.

Next, using this bladder rubber sheet and an unvulcanized tire inner surface rubber sheet not coated with a release agent for the inner surface of the tire, the vulcanization and peeling operations were repeated twice, and two more unexposed sheets were added. It was confirmed that the rubber tire inner rubber sheet could be released. However, a third vulcanization or peeling operation was performed, but peeling was not possible.
The same results as described above were obtained when a tire was produced from a green tire using the release agent 3. That is, it was confirmed that two tires could be produced in succession by repeating the vulcanization and peeling operations twice using a raw tire to which a release agent for the tire inner surface was not applied. However, although the third vulcanization and peeling operation was performed, the peeling was not possible and the third tire could not be manufactured.

Example 4
In Example 1, except that the release agent for the tire inner surface was applied to the bladder rubber sheet instead of the unvulcanized tire inner surface rubber sheet, the evaluation of the release agent for the tire inner surface (model experiment) was carried out in the same manner. Similar results as in Example 1 were obtained.
In Example 1, the evaluation of the release agent for the tire inner surface (tire manufacturing experiment) was similarly conducted except that the release agent for the tire inner surface was applied to the outer surface of the bladder instead of the inner surface of the raw tire. Similar results as in Example 1 were obtained.

Example 5
Except that the release agent 1 was changed to the release agent 2 in Example 4, the evaluation of the release agent for the tire inner surface (model experiment) and (tire manufacturing experiment) were carried out in the same manner as in Example 2. Results were obtained.

Example 6
Except that the release agent 1 was changed to the release agent 3 in Example 4, the evaluation of the release agent for the tire inner surface (model experiment) and (tire manufacturing experiment) were carried out in the same manner as in Example 3. Results were obtained.

[Comparative Example 1]
(Preparation of release agent for tire inner surface)
Comparative release agent 1 was obtained in the same manner as in Example 1, except that the silicone-based nonionic surfactant was changed to an oil-in-water emulsion of dimethylpolysiloxane (kinematic viscosity 10000 cSt) in Example 1. It was.

(Evaluation of release agent for tire inner surface)
When the comparative mold release agent 1 was used, the tensile load was 1.5 N, and it was confirmed that sufficient smoothness was obtained.
When the vulcanized rubber sheet was peeled off, it was easily peeled off. However, the component of the release agent did not transfer sufficiently from the peeled vulcanized rubber sheet to the bladder rubber sheet surface, and was not transferred.

Therefore, this bladder rubber sheet and an unvulcanized tire inner surface rubber sheet not coated with a release agent for the inner surface of the tire were used for vulcanization, but it is natural that both sheets cannot be peeled off. The operation of vulcanization and peeling could not be repeated any more.
When a tire was produced from a green tire using the comparative release agent 1, a normal tire was obtained at the first time. However, vulcanization was performed using the bladder obtained after peeling from the inner surface of the tire and the raw tire to which the release agent for the inner surface of the tire was not applied, but the tire and the bladder could not be peeled off. However, the vulcanization and peeling operations could not be repeated any more.

[Comparative Example 2]
(Preparation of release agent for tire inner surface)
6 parts of oil-in-water emulsion of dimethylpolysiloxane (base oil viscosity: about 10,000 mPa · s, dimethylpolysiloxane content: 40%), 7 parts of tap water, mascobite mica (Yamaguchi) Mica; average particle size 40 μm) 4 parts, talc (Matsumura Sangyo Co., Ltd .; crown talc pharmacopoeia PP; average particle size 11 μm) 10 parts, sodium carboxymethylcellulose (viscosity of 1% aqueous solution: 10 mPa · s) 0.5 And 1 part of sodium dodecylbenzenesulfonate were added, and uniformly dissolved and dispersed using a homomixer to prepare comparative mold release agent 2.

(Evaluation of release agent for tire inner surface)
The same result as in Comparative Example 1 was obtained.
The results of Examples 1 to 3 and Comparative Examples 1 and 2 are summarized in Table 1.

* 1 Alkyl silicone content 50%
* 2 40% dimethyl silicone content
* 3 Evaluation of smoothness * 4 A bladder rubber sheet was superimposed on the coated surface of the unvulcanized tire inner surface rubber sheet coated with a release agent for the inner surface of the tire, and then the vulcanized rubber sheet was peeled off. Using the bladder rubber sheet obtained at that time and the unvulcanized tire inner surface rubber sheet to which the release agent for the inner surface of the tire is not applied, the number of repetitions when repeating the vulcanization and peeling operations (that is, Number of times of vulcanization and peeling operations corresponding to the second molding process)
* 5 In the above * 4, except that the inner surface of the actual raw tire (215 / 60R16 size) is used instead of the unvulcanized tire inner rubber sheet, and the actual outer surface of the bladder is used instead of the bladder rubber sheet. * 4 In the same manner as above, vulcanization was performed to obtain a tire. Using the bladder obtained at that time and the raw tire to which the release agent for the inner surface of the tire is not applied, the number of repetitions when the tire is manufactured by repeating the vulcanization and peeling operations (that is, the second molding) Number of times tires were manufactured in the process)

Claims (8)

  A mold release agent for the tire inner surface, comprising an alkyl silicone, a silicone nonionic surfactant having a cloud point of 20 to 60 ° C. and a kinematic viscosity of 10 to 60 cSt (25 ° C.), an inorganic component made of powder, and water. .   The tire according to claim 1, wherein a weight ratio of the silicone-based nonionic surfactant is 0.01 to 20% by weight with respect to a total amount of the alkyl silicone, the silicone-based nonionic surfactant, and the inorganic component. Release agent for inner surface.   The mold release agent for tire inner surfaces of Claim 1 or 2 whose weight ratio of an inorganic component is 2 to 40 weight% with respect to the total amount of the said alkyl silicone, a silicone type nonionic surfactant, and an inorganic component.   The critical micelle formation concentration (CMC) of the silicone-based nonionic surfactant is 1000 mg / L or less (25 ° C.), and the surface tension (γCMC) at the critical micelle formation concentration is 15 to 40 mN / m (25 ° C.). The release agent for tire inner surfaces according to any one of claims 1 to 3.   The mold release agent for tire inner surfaces in any one of Claims 1-4 whose said inorganic component is calcium carbonate. Applying the release agent for the tire inner surface according to any one of claims 1 to 5 to an inner surface of a raw tire and / or an outer surface of a bladder, the bladder is heated and expanded to press-fit the raw tire into a mold, A first molding step for vulcanization molding;
A second molding step in which the bladder is heated and expanded to press another raw tire into a mold and vulcanize;
The manufacturing method of the tire containing this.   The tire manufacturing method according to claim 6, wherein the second molding step is performed at least three more times. Wherein the second molding step is carried out without also coating the fabric in any release agent for tire inner surface of another green tire inner surface and the outer surface of the bladder, the tire manufacturing method according to claim 6 or 7.