JP2016040080A - Mold release agent for tire inner surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold release agent for a tire inner surface having excellent releasability between a raw tire inner surface and a bladder, and a tire where the mold release agent for a tire inner surface is hardly released from the tire inner surface.SOLUTION: A mold release agent for a tire inner surface contains fired kaolin having an oil absorption amount of 50 ml/100 g or more. It preferably contains further a silicone component, a surfactant and water. It is preferable that the weight percentage of the fired kaolin is 10 to 90 wt.%, the weight percentage of the silicone component is 10 to 75 wt.% and the weight percentage of the surfactant is 1 to 20 wt.% based on the total amount of the fired kaolin, the silicone component and the surfactant.SELECTED DRAWING: None

Description

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

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 so that the unvulcanized green tire is placed in the mold. This is done by press molding.
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 tire inner surface mainly has the performance to give good lubricity between the inner surface of the raw tire and the bladder (smoothness), and the ability to release the air that has entered the inner surface of the bladder and the raw tire and to bring them into close contact (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. In particular, inorganic powders derived from natural minerals and clays have been suitable for the composition of solid particles.
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 mold release agent for a tire inner surface.
Patent Document 2 discloses a mold release agent composition for tire molding comprising a diorganopolysiloxane emulsion, mica powder or talc powder, a powder having a melting point of 200 ° C. or less, and water.
In Patent Document 3, a release film of silicone rubber is formed, a release agent containing at least one of talc powder and mica powder is applied on the release film, and the release film and the release agent are provided. A method is shown in which a raw tire is put into a mold and vulcanized while inflating a bladder in the tire cavity.

JP 2005-193448 A Japanese Patent Application Laid-Open No. 08-039575 JP 2005-246627 A

In recent years, since the composition ratio of butyl rubber in the rubber used on the tire inner surface has increased, the tendency to adhere to the bladder has increased.
However, increasing the adhesion amount of the release agent for the tire inner surface in order to obtain releasability makes it easier for the release agent component to fall from the inner surface of the tire after completion, and adheres to the tire inner surface by hand. The problem of doing so began to occur. Therefore, there has been a demand for a mold release agent for the tire inner surface that has better mold release performance and further prevents components from dropping from the completed tire inner surface.
The problem to be solved by the present invention is to provide a release agent for the tire inner surface having excellent releasability between the inner surface of the raw tire and the bladder, and a release agent component for the tire inner surface from the tire inner surface. It is to provide a tire that is difficult to fall off.

As a result of intensive studies to solve the above problems, the present inventors have found that the conventional problems can be solved all at once by including a specific calcined kaolin in the mold release agent for the tire inner surface. The invention has been reached.
The mold release agent for a tire inner surface of the present invention contains calcined kaolin having an oil absorption of 50 ml / 100 g or more.
It is preferable to further contain a silicone component, a surfactant and water.
The weight ratio of the calcined kaolin is 10 to 90% by weight, the weight ratio of the silicone component is 10 to 75% by weight, and the weight ratio of the surfactant is 1 to the total amount of the calcined kaolin, the silicone component and the surfactant. It is preferable that it is 20 weight%.
The tire of the present invention is formed by attaching the above-mentioned release agent for the inner surface of the tire to the inner surface of the raw tire and vulcanizing it.

  The mold release agent for tire inner surface of the present invention has good mold release performance. Moreover, even if the inner surface of the tire obtained when this release agent for the tire inner surface is attached to the inner surface of the raw tire and vulcanized, the release agent component for the tire inner surface does not adhere to the hand even when touched by hand.

  Each component mix | blended with the mold release agent for tire inner surfaces of this invention is demonstrated, and the mold release agent for tire inner surfaces is explained in full detail.

[Baking kaolin]
The calcined kaolin is an essential component in the present invention, and has excellent release properties and drop-off prevention properties.
The oil absorption of the calcined kaolin used in the present invention is 50 ml / 100 g or more, preferably 60 ml / 100 g or more, more preferably 80 ml / 100 g or more. If calcined kaolin having an oil absorption of less than 50 ml / 100 g is used, a sufficient effect of preventing the release agent component for the tire inner surface from falling off cannot be obtained.

The higher the oil absorption, the harder it is to remove the release agent component for the tire inner surface. The reason why the release agent component for the tire inner surface is less likely to fall off compared with the case where the calcined kaolin having a higher oil absorption is lower is not clear, but is estimated as follows.
In general, the higher the oil absorption, the greater the specific surface area. On the other hand, since the particle surface is charged, it has adhesion to the rubber surface. Therefore, the higher the oil absorption amount, the greater the total area having adhesion, so that the drop-off preventing property is excellent.

The upper limit of the oil absorption amount of the calcined kaolin used in the present invention is 200 ml / 100 g.
The oil absorption is measured by a method according to JIS K-5101-13-1. The procedure is as follows. First, the calcined kaolin sample is left in a dryer maintained at 70 to 80 ° C. for 10 hours, and then naturally cooled to room temperature in a desiccator. Then weigh about 1 gram of sample on a glass plate and record the exact weight. Next, the refined linseed oil is kneaded with a spatula so as to be uniform evenly while being dripped little by little from the burette to the center of the calcined kaolin sample. The dripping and kneading are repeated, and the end point is the point when the whole becomes a uniform mass and can be spirally wound with a spatula. The oil absorption is determined by the following equation (1).
Oil absorption (ml / 100 g) = Drip amount of refined linseed oil (ml) / Weight of calcined kaolin sample (g) × 100 (1)

  The average primary particle size of the calcined kaolin is not particularly limited, but is preferably 0.1 to 30 μm, and more preferably 0.1 to 10 μm. When the average primary particle size of the calcined kaolin is less than 0.1 μm, not only sufficient releasability is not obtained, but also a problem that dust is likely to be scattered around in the process of attaching the release agent. . On the other hand, when the diameter is larger than 30 μm, a problem such as blocking of the spray gun nozzle tends to occur in the step of attaching the release agent using a spray gun or the like.

The calcined kaolin is mainly obtained by treating wet kaolin at a high temperature, and the crystal structure is changed by releasing crystal water.
The firing temperature when producing the calcined kaolin is usually in the range of 500 to 1200 ° C. The firing temperature in the present invention is preferably 500 to 900 ° C, more preferably 525 to 800 ° C, and most preferably 550 to 700 ° C. If the calcination temperature is less than 500 ° C., the crystal water is not released and becomes uncalcined kaolin, and sufficient releasability may not be obtained. On the other hand, if it exceeds 1200 ° C., the releasability of the calcined kaolin is remarkably deteriorated and may become an inner surface release agent having insufficient releasability.

The wet kaolin mainly used as a raw material for calcined kaolin is obtained by purifying and bleaching kaolin raw earth mined from kaolin deposits with water to remove impurities. On the other hand, what refine | purified and classified by dry and adjusted the particle size is called dry kaolin. The calcined kaolin used in the present invention may be obtained by calcining either wet kaolin or dry kaolin. Moreover, you may add the dry or wet kaolin which has not performed baking processing to baking kaolin.
Examples of the calcined kaolin include commercially available products such as Neogen 2000, Polestar 450, ARGICAL-C88R, MetaStar 501 (Imeris), Iceberg, Opti White (Burges Pigment).

[Silicone component]
When the release agent for tire inner surface of the present invention contains a silicone component, the release property and lubricity are improved. Silicone is a general term for organopolysiloxanes, and includes silicone oil, silicone rubber, and silicone resin. The silicone component contains 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, 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 100 to 500,000 cSt, more preferably from 300 to 100,000 cSt, in terms of the balance between releasability and product stability.
As the silicone component, an emulsion of silicone may be used in the production of the release agent for the tire inner surface.

[Surfactant]
The surfactant not only disperses the calcined kaolin in water and improves the dispersion stability of the release agent for the inner surface of the tire, but also repels liquid when the release agent for the inner surface of the tire is applied to the raw tire with a spray device or the like. Provides preventing properties (wetting). The wettability can be adjusted by adjusting the blending amount.
The surfactant may be at least one selected from nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants, and preferably nonionic surfactants and / or Or it is an anionic surfactant.

  The nonionic surfactant is not particularly limited, but examples thereof include polyoxyalkylene alkyl ethers such as polyoxyethylene cetyl ether and polyoxyethylene lauryl ether; polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether and the like. Polyoxyalkylene alkyl phenyl ethers; polyoxyalkylene fatty acid esters such as polyoxyethylene monolaurate and polyoxyethylene monooleate; polyoxyalkylene sorbitans such as polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate Fatty acid ester; polyoxyalkylene hydrogenated castor oil; polyoxyalkylene sorbitol fatty acid ester; polyglycerin fatty acid ester; alkyl Li serine ether; polyoxyalkylene cholesteryl ether; alkylpolyglucosides; sucrose fatty acid esters; polyoxyalkylene alkylamine; oxyethylene over oxypropylene block polymers and the like. In the present invention, a polyoxyalkylene type such as polyoxyethylene alkyl ether / polyoxypropylene alkyl ether (wherein alkyl may be any one of 1 to 3) is desirable from the viewpoint of the effect of dispersing the fired kaolin in water. A nonionic surfactant may use together 1 type (s) or 2 or more types.

  The anionic surfactant is not particularly limited. For example, fatty acid salts such as sodium oleate, potassium palmitate, triethanolamine oleate; sodium lauryl sulfate, ammonium lauryl sulfate, sodium stearyl sulfate, sodium cetyl sulfate, etc. Alkyl sulfate ester salt; Polyoxyalkylene alkyl ether acetate salt such as sodium polyoxyethylene tridecyl ether acetate; Alkylbenzene sulfonate salt such as sodium dodecylbenzene sulfonate; Polyoxyalkylene alkyl ether sulfate salt; Stearoylmethyl taurine Na, Lauroylmethyl Higher fatty acid amide sulfonates such as taurine Na, myristoyl methyl taurine Na, palmitoyl methyl taurine Na; lauroyl sarcosine natri N-acyl sarcosine salts such as sodium; alkyl phosphates such as sodium monostearyl phosphate; polyoxyalkylene alkyl ether phosphates such as sodium polyoxyethylene oleyl ether phosphate and sodium polyoxyethylene stearyl ether phosphate; Long-chain sulfosuccinates such as sodium di-2-ethylhexylsulfosuccinate and sodium dioctylsulfosuccinate, long-chain N-acyl glutamates such as sodium monosodium N-lauroylglutamate and disodium N-stearoyl-L-glutamate It is done.

  In the present invention, a carboxylic acid type anionic surfactant, a sulfonic acid type anionic surfactant and the like are suitable from the viewpoint of the effect of attaching a release agent for the tire inner surface, and a carboxylic acid type anionic surfactant. Then, polyoxyethylene alkyl ether carboxylate and the like are particularly suitable. As the sulfonic acid type 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.

  Examples of the cationic surfactant include alkyltrimethylammonium salts such as stearyltrimethylammonium chloride, lauryltrimethylammonium chloride, and cetyltrimethylammonium bromide; dialkyldimethylammonium salts; trialkylmethylammonium salts and alkylamine salts.

  Examples of amphoteric surfactants include 2-undecyl-N, N- (hydroxyethylcarboxymethyl) -2-imidazoline sodium, 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, and the like. Imidazoline-based amphoteric surfactants; 2-heptadecyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine, lauryldimethylaminoacetic acid betaine, alkylbetaines, amide betaines, sulfobetaine, and other betaine-based amphoteric surfactants; N- Amino acid type amphoteric surfactants such as lauryl glycine, N-lauryl β-alanine, N-stearyl β-alanine and the like can be mentioned.

In order to improve dispersion stability and wettability, two or more surfactants may be used in combination, and examples thereof include a combination system of a nonionic surfactant and an anionic surfactant.
When the release agent for the tire inner surface contains a nonionic surfactant and an anionic surfactant, the respective weight ratios are not particularly limited, but the influence on foaming and the reason for dispersion stability of inorganic components Therefore, the nonionic surfactant / anionic surfactant (weight ratio) is preferably 75/25 to 99/1, more preferably 85/15 to 98/2, and 90/10 to 95 / 5 is particularly preferable.

[Inorganic ingredients]
In the present invention, an inorganic powder component (hereinafter sometimes simply referred to as “inorganic component”) may be included in addition to the calcined kaolin. The inorganic component is a component mainly used for imparting 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, clintnite, muscovite, biotite, phlogopite, synthetic mica, fluorine mica, paragolite , Phlogopite, repidolite, tetrasilic mica, teniolite and other phyllosilicates; antigolite and other jamon stones; donpasite, sudite, kukkaite, clinochlore, chamosite Chlorite, chlorite, nanlite, etc .; Sepiolite, attapulgite, attapulgus clay, paliolite, such as palygorskite; (heavy) carbonates such as calcium carbonate, magnesium carbonate, barium carbonate; calcium sulfate, barium sulfate, etc. Sulfates; Metal oxides such as silica, alumina, 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; graphite and the like can be mentioned. These components may be used alone or in combination of two or more. It is preferable that the inorganic component is at least one selected from diatomaceous earth, mica, and talc because it is inexpensive.

  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. If it is smaller than 1 μm, when preparing the mold release agent for the tire inner surface, there may be a case where the inorganic powder is poorly dispersed and the air permeability is insufficient when the tire is vulcanized. On the other hand, if it is larger than 30 μm, the smoothness may be insufficient during tire vulcanization.

〔water〕
The water can uniformly disperse the calcined kaolin contained in the release agent for the tire inner surface, and can evenly adhere the release agent for the tire inner surface to the inner surface of the raw tire. The water may be any of distilled water, ion exchange water, tap water, industrial water, underground water, and the like. Moreover, alcohols such as ethanol may be added for the purpose of facilitating the adhesion of the release agent for the tire inner surface.

[Releasing agent for tire inner surface and manufacturing method thereof]
The mold release agent for a tire inner surface according to the present invention includes calcined kaolin (hereinafter simply referred to as calcined kaolin) having an oil absorption of 50 ml / 100 g or more. Moreover, it is preferable that a silicone component, surfactant, and water are included.
In the mold release agent for tire inner surfaces of the present invention, the fired kaolin is contained, so that the mold release property is excellent. The tire obtained when the release agent for the tire inner surface is attached to the inner surface of the raw tire and vulcanized has a characteristic that it is difficult for components to adhere to the hand even if the tire inner surface is touched by hand.

  Although there are no particular limitations on the weight ratio of the calcined kaolin, inorganic component, silicone component, surfactant, and water contained in the release agent for the tire inner surface, the blending ratio described below is preferable.

  The weight ratio of the calcined kaolin is preferably 1 to 90% by weight, more preferably 10 to 85% by weight, still more preferably 30 to 70%, particularly preferably based on the total amount of the calcined kaolin, the silicone component and the surfactant. Is 40-60% by weight. When there is too little calcined kaolin, mold release property or lubricity may deteriorate. Moreover, when there is too much calcined kaolin, calcined kaolin may fall off from the molded tire inner surface, and the periphery of the tire storage location may be soiled.

  The weight ratio of the silicone component is preferably 10 to 75% by weight, more preferably 20 to 60% by weight, particularly preferably 30 to 50% by weight, based on the total amount of the calcined kaolin, the silicone component and the surfactant. . When there are too few silicone components, a mold release agent may deteriorate. Moreover, when there are too many silicone components, smoothness may deteriorate.

  The weight ratio of the surfactant is preferably 1 to 20% by weight, more preferably 1 to 15% by weight, particularly preferably 2 to 10% by weight based on the total amount of the calcined kaolin, the silicone component and the surfactant. is there. If the amount of the surfactant is too small, liquid repellency may occur on the inner surface of the raw tire during application, and the storage stability of the release agent for the inner surface of the tire may deteriorate. Moreover, when there are too many surfactants, the coating defect may generate | occur | produce by the deterioration of smoothness or foaming of the mold release agent for tire inner surfaces.

The mold release agent for a tire inner surface of the present invention may contain additives such as a thickener, an antifoaming agent, a preservative, and a fragrance as required in addition to the components described above.
About the manufacturing method of the mold release agent for tire inner surfaces of this invention, if the process of mixing baking kaolin, a silicone component, surfactant, and water is included, there will be no limitation in particular about a mixing order, the mixing equipment to be used, etc. .

〔tire〕
The tire of the present invention is obtained by attaching the above-described release agent for the tire inner surface to the inner surface of the raw tire and vulcanizing it.
The tire of the present invention can be manufactured, for example, through an adhesion process and a vulcanization process described below.

[Adhesion process]
In the attaching step, first, a tire original form called a raw tire is prepared by combining and bonding necessary members such as a bead wire and a tire cord mainly with unvulcanized rubber.
Subsequently, the mold release agent for tire inner surfaces of this invention is made to adhere to this raw tire inner surface. As a method for attaching the release agent for the tire inner surface, spraying with an air gun or an airless gun is generally used, but a brush coating or a centrifugal coating machine may be used. The adhesion amount of the release agent for the tire inner surface varies depending on the use and size of the tire product, but is preferably 10 to 50 g / m ² after drying. When the adhesion amount of the release agent for the tire inner surface is small, sufficient release agent performance cannot be obtained. On the other hand, when the adhesion amount is too large, a large amount of the release agent component may fall off and stain the periphery. Thereafter, until the release agent for the tire inner surface attached to the inner surface is sufficiently dried, the raw tire is left for several days if it is several tens of minutes to longer at room temperature.

[Vulcanization process]
Vulcanization is performed as follows on the dry green tire obtained in the adhesion step. First, the raw tire is placed in a metal mold, and a rubber bag called a bladder is pressed at high temperature with steam or the like from the inside to press the raw tire against the mold to obtain the final tire shape and tread. Vulcanize to form a pattern. 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.
The tire of the present invention is advantageous in handling because the release agent component for the tire inner surface does not fall off from the tire inner surface as compared with the conventional tire.

  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”.

[Example 1]
(Preparation and evaluation of release agent)
25.0 parts of calcined kaolin (a) having an oil absorption of 55 ml / 100 g was mixed with 31.0 parts of tap water to prepare a slurry. Subsequently, an oil-in-water emulsion of dimethylpolysiloxane (base oil viscosity: about 50,000 mPa · s, solid content: 40%), 40 parts of polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 1. 8 parts, 0.2 parts of sodium dodecylbenzenesulfonate, 0.1 part of xanthan gum, 1.0 part of antifoaming agent and 0.9 part of preservative are added, and uniformly dissolved and dispersed using a high-speed shearing device The mold release agent (a) was prepared. About this mold release agent (a), evaluation using the rubber specimen shown below and evaluation by tire manufacture were performed, and mold release property and drop-off prevention property were evaluated. As a result of the evaluation, as shown in Table 1, the releasability and prevention of falling off were good.

(Evaluation using rubber specimen)
On a 4 cm × 7 cm × 0.5 cm unvulcanized rubber sheet, a tire inner surface release agent was adhered only to 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 pressurized by applying pressure at 20 ° C. for 20 minutes at a temperature of 180 ° C. And vulcanized evaluation rubber was obtained. After the vulcanization was completed, the mold release property and drop-off prevention property were evaluated. The evaluation criteria are as follows.
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. Drop-off prevention property General-purpose rubber sheet of size 1.4cm x 1.4cm x 0.5cm with a vertical load of 0.2kg / square centimeter applied to the vulcanized evaluation rubber surface after the release property evaluation is 200cm / min. The product was pulled 5 cm horizontally at a speed of 5 mm to evaluate the ability of the release agent component for the tire inner surface to fall off.
A: No omission is observed.
○: There is partial omission.
X: There is remarkably omission.

(Evaluation using tires)
The tire inner surface release agent obtained above was applied to the inner surface of a 215 / 60R16 size raw tire so that the coating amount after drying was 15 g / m ² . Next, ten tires coated with a release agent were pressurized at a mold temperature of 180 ° C. and a pressure of 20 kg / cm ² for 20 minutes and vulcanized. After completion of vulcanization, release properties were evaluated. The evaluation criteria are as follows.

1. Releaseability When the bladder is released from the vulcanized tire, releaseability is evaluated visually.
A: All 10 pieces are easily released.
○: There is one or more tires that are released but temporarily deformed.
X: There is one or more tires that are released but partially deformed after completion.
2. Fall-off prevention property The inside surface of the vulcanized tire was rubbed by hand, and the fall-off prevention property of the release agent component for the tire inside surface was visually evaluated.
A: The component does not adhere to the hand.
○: There is no scattering of components around, but the components adhere to the hands.
X: The component adheres to the hand at all, and the component is scattered around the periphery.

[Examples 2 to 5]
Except for changing the calcined kaolin (a) used in Example 1 to calcined kaolins (b) to (e) having oil absorptions of 60 ml / 100 g, 70 ml / 100 g, 80 ml / 100 g, and 90 ml / 100 g, respectively. Thus, a release agent for the tire inner surface was prepared, and release agents (b) to (e) were obtained. The evaluation results are shown in Table 1.

Example 6
A slurry was prepared by mixing 15.0 parts of calcined kaolin (a) used in Example 1, 10 parts of sericite mica powder having an average particle size of 8 μm, and 31.0 parts of water. Subsequently, an oil-in-water emulsion of dimethylpolysiloxane (base oil viscosity: about 50,000 mPa · s, solid content: 40%), 40 parts of polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 1. 8 parts, 0.2 parts of sodium dodecylbenzenesulfonate, 0.1 part of xanthan gum, 1.0 part of antifoaming agent and 0.9 part of preservative are added, and uniformly dissolved and dispersed using a high-speed shearing device The mold release agent (f) was prepared. The evaluation results are shown in Table 1.

Example 7
A slurry was prepared by mixing 40.0 parts of calcined kaolin (a) used in Example 1, 20 parts of sericite mica powder having an average particle diameter of 8 μm, and 36.0 parts of water. Next, 1.8 parts of polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 9, 0.2 parts of sodium dodecylbenzenesulfonate, 0.1 part of xanthan gum as a thickener, 1.0 part of an antifoaming agent, 0.9 parts of a preservative was added, and the mixture was uniformly dissolved and dispersed using a high-speed shearing device to prepare a release agent (f). The evaluation results are shown in Table 1.

(Preparation and evaluation of comparative release agent)
[Comparative Example 1]
A slurry was prepared by mixing 25.0 parts of calcined kaolin (f) having an oil absorption of 40 ml / 100 g with 31.0 parts of tap water. Subsequently, an oil-in-water emulsion of dimethylpolysiloxane (base oil viscosity: about 50,000 mPa · s, solid content: 40%), 40 parts of polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 1. 8 parts, 0.2 parts of sodium dodecylbenzenesulfonate, 0.1 part of xanthan gum as a thickener, 1 part of antifoaming agent, 0.9 part of preservative, and uniformly dissolved and dispersed using a high-speed shearing device, A comparative release agent (h) was prepared. The evaluation results are shown in Table 2.

[Comparative Example 2]
In place of the comparative calcined kaolin (f) used in [Comparative Example 1], a comparative calcined kaolin (g) having an oil absorption of 35 ml / 100 g was used. As in [Comparative Example 1], a comparative mold release agent (i) Got. The evaluation results are shown in Table 2.

[Comparative Example 3]
A slurry was prepared by mixing 25.0 parts of wet kaolin powder having an average particle size of 0.5 μm with 31.0 parts of tap water. Subsequently, an oil-in-water emulsion of dimethylpolysiloxane (base oil viscosity: about 50,000 mPa · s, solid content: 40%), 40 parts of polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 1. 8 parts, 0.2 parts of sodium dodecylbenzenesulfonate, 0.1 part of xanthan gum as a thickener, 1 part of antifoaming agent, 0.9 part of preservative, and uniformly dissolved and dispersed using a high-speed shearing device, A comparative release agent (j) was prepared. The evaluation results are shown in Table 2.

[Comparative Example 4]
A slurry was prepared by mixing 25.0 parts of light calcium carbonate powder having an average particle size of 5 μm with 31.0 parts of tap water. Subsequently, an oil-in-water emulsion of dimethylpolysiloxane (base oil viscosity: about 50,000 mPa · s, solid content: 40%), 40 parts of polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 1. 8 parts, 0.2 parts of sodium dodecylbenzenesulfonate, 0.1 part of xanthan gum as a thickener, 1 part of antifoaming agent, 0.9 part of preservative, and uniformly dissolved and dispersed using a high-speed shearing device, A comparative release agent (k) was prepared. The evaluation results are shown in Table 2.

[Comparative Example 5]
A slurry was prepared by mixing 25.0 parts of sericite mica powder having an average particle diameter of 8 μm with 31.0 parts of tap water. Subsequently, an oil-in-water emulsion of dimethylpolysiloxane (base oil viscosity: about 50,000 mPa · s, solid content: 40%), 40 parts of polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 1. 8 parts, 0.2 parts of sodium dodecylbenzenesulfonate, 0.1 part of xanthan gum as a thickener, 1 part of antifoaming agent, 0.9 part of preservative, and uniformly dissolved and dispersed using a high-speed shearing device, A comparative release agent (1) was prepared. The evaluation results are shown in Table 2.

As can be seen from Table 1, since the mold release agents for tire inner surfaces of Examples 1 to 8 contain calcined kaolin having an oil absorption amount of 50 ml / 100 g or more, the mold release properties and drop-off prevention properties are excellent.
On the other hand, as can be seen from Table 2, the tire inner surface release agents of Comparative Examples 1 and 2 use calcined kaolin, but the oil absorption is less than 50 ml / 100 g, so the effects of the present application are obtained. Absent. In addition, when wet kaolin is used instead of calcined kaolin (Comparative Example 3), when kaolin is not included (Comparative Examples 4 and 5), the effect of the present application is not obtained.

Claims (4)

  A mold release agent for a tire inner surface, comprising calcined kaolin having an oil absorption of 50 ml / 100 g or more.   The mold release agent for tire inner surfaces of Claim 1 which further contains a silicone component, surfactant, and water.   The weight ratio of the calcined kaolin is 10 to 90% by weight, the weight ratio of the silicone component is 10 to 75% by weight, and the weight ratio of the surfactant is 1 to the total amount of the calcined kaolin, the silicone component and the surfactant. The mold release agent for tire inner surfaces of Claim 2 which is 20 weight%.   A tire obtained by adhering a release agent for a tire inner surface according to any one of claims 1 to 3 to an inner surface of a raw tire and vulcanizing the tire.