JP7713438B2 - RUBBER INTERNAL SURFACE RELEASE AGENT, METHOD FOR PRODUCING RUBBER INTERNAL SURFACE RELEASE AGENT, AQUEOUS DISPERSION OF RUBBER INTERNAL SURFACE RELEASE AGENT, METHOD FOR PRODUCING RUBBER PRODUCT, METHOD FOR PRODUCING TIRE, RUBBER PRODUCT AND TIRE - Google Patents

Description

The present invention relates to a release agent for rubber inner surfaces, a method for producing a release agent for rubber inner surfaces, an aqueous dispersion of a release agent for rubber inner surfaces, a method for producing a rubber product, a method for producing a tire, a rubber product, and a tire.

One type of rubber release agent is a release agent for the inner surface of a tire. For example, Patent Document 1 describes a release agent for the inner surface of a tire that contains an inorganic component (inorganic powder) made of powder, a silicone component, a surfactant, a polyhydric alcohol, and water.

JP 2012-228783 A

For example, release agents for the inner surface of tires are used as follows. That is, in the tire manufacturing process, a rubber bag called a bladder is placed inside the unvulcanized raw tire during vulcanization molding of the unvulcanized raw tire, and the bladder is expanded with hot air, hot water, or steam to press the unvulcanized raw tire into the inside of a mold, and vulcanization is performed while press molding. To ensure that this process is carried out smoothly, the inner liner surface (inner surface) of the raw tire is sprayed with a release agent for the inner surface of tires beforehand (inside paint). For this reason, in order to reduce the tire defect rate during the manufacturing process and maintain a good product appearance, it is important to keep the condition of the spray-applied surface uniform.

For inside paint, as in Patent Document 1, for example, a tire inner surface release agent (rubber inner surface release agent) is used, which has a structure in which the surface of a hydrophobic inorganic powder is coated with a hydrophobic release component. In this case, poorly dispersed matter in water is generated due to aggregation of the hydrophobic inorganic powder during powder preparation or water dispersion, and aggregates are generated on the spray-applied surface, which may cause an increase in tire rejection rate and deterioration of product appearance. In order to suppress or prevent the generation of such aggregates (poorly dispersed matter), for example, a dispersant can be added to the rubber inner surface release agent.

On the other hand, rubber inner surface release agents are generally stored and used in the form of an aqueous dispersion. If an excessive amount of dispersant is added to the rubber inner surface release agent in order to suppress or prevent the generation of agglomerates (poorly dispersed materials), the hydrophobic release component may peel off from the surface of the hydrophobic inorganic powder. In other words, the excessive addition of dispersant may reduce the dispersion stability of the rubber inner surface release agent aqueous dispersion. If the hydrophobic release component peels off from the surface of the hydrophobic inorganic powder, oil spots may occur after the rubber inner surface release agent is sprayed, which may cause poor appearance.

As such, it is difficult to simultaneously suppress or prevent the occurrence of agglomerates and suppress or prevent the occurrence of oil spots after application in a release agent for the inner surface of rubber.

Therefore, the present invention aims to provide a release agent for rubber inner surfaces that can simultaneously suppress or prevent the occurrence of agglomerates and suppress or prevent the occurrence of oil spots after application, a method for producing a release agent for rubber inner surfaces, an aqueous dispersion of a release agent for rubber inner surfaces, a method for producing a rubber product, a method for producing a tire, a rubber product, and a tire.

In order to achieve the above object, the release agent for the inner surface of rubber of the present invention is characterized by comprising the following components (A) to (D).

(A) Inorganic component (B) Hydrophobic silicone (C) At least one anionic surfactant selected from the group consisting of (c1) and (c2) below: (c1) Sulfate ester type anionic surfactant (c2) Sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonate salts)
(D) a nonionic surfactant having an HLB value of 7.2 to 11.5 according to the Griffin method

The method for producing a release agent for a rubber inner surface of the present invention is a method for producing the release agent for a rubber inner surface of the present invention,
a first mixing step of mixing a portion of the component (C) and the component (B) to obtain a mixture;
a second mixing step of mixing the remainder of the component (C), the component (A), and the component (D) with the mixture obtained in the first mixing step;
The present invention is characterized by comprising:

The aqueous dispersion of a release agent for rubber inner surfaces of the present invention is characterized by containing the release agent for rubber inner surfaces of the present invention and water.

The method for producing a rubber product of the present invention is characterized in that it includes a pretreatment step for release in which the aqueous dispersion of the release agent for rubber inner surfaces of the present invention is directly or indirectly applied to the inner surface of the rubber, and the water is then volatilized.

The method for producing a tire of the present invention includes the steps of:
a pretreatment step for release in which an aqueous dispersion of a release agent for the inner surface of a tire, the aqueous dispersion containing the release agent for the inner surface of a rubber according to the present invention and water, which is a release agent for the inner surface of a tire, is applied to at least one of the inner surface of an unvulcanized rubber green tire and the outer surface of a bladder, and the water is then volatilized;
a vulcanization step in which, after the pretreatment step for mold release, the bladder housed in the raw tire in a molding die is expanded to press an outer surface of the raw tire against an inner surface of the molding die, and the raw tire is heated and vulcanized in this state;
The present invention is characterized by comprising:

The rubber product of the present invention is characterized in that the rubber inner surface release agent of the present invention is adhered to the rubber inner surface.

The first tire of the present invention is characterized in that the rubber inner surface release agent of the present invention, which is a tire inner surface release agent, is adhered to the inner surface of the tire.

The second tire of the present invention is characterized in that the tire inner surface release agent of the present invention, which is a tire inner surface release agent, is adhered to the inner surface of a raw tire and vulcanized. In the following, the first tire of the present invention and the second tire of the present invention may be collectively referred to as the "tire of the present invention."

According to the present invention, it is possible to provide a release agent for rubber inner surfaces that can simultaneously suppress or prevent the occurrence of agglomerates and suppress or prevent the occurrence of oil spots after application, a method for producing a release agent for rubber inner surfaces, an aqueous dispersion of a release agent for rubber inner surfaces, a method for producing a rubber product, a method for producing a tire, a rubber product, and a tire.

The present invention will be described in more detail below. However, the present invention is not limited to the following description.

The release agent for the inner surface of rubber of the present invention may be, for example,
the (c1) is at least one selected from the group consisting of alkyl sulfates, alkenyl sulfates, polyoxyalkylene alkyl ether sulfates, and polyoxyalkylene alkenyl ether sulfates;
The (c2) may be at least one selected from the group consisting of olefin sulfonate, α-sulfofatty acid ester salt, and dialkyl sulfosuccinate.

The rubber inner surface release agent of the present invention may contain, for example, 5 to 1,000 parts by mass of component (D) per 100 parts by mass of component (C).

The release agent for the inner surface of rubber of the present invention may be, for example, a release agent for the inner surface of a tire. In the following, the release agent for the inner surface of rubber of the present invention, which is a release agent for the inner surface of a tire, may be referred to as the "release agent for the inner surface of a tire of the present invention."

[1. Release agent for rubber inner surface]
As described above, the release agent for the inner surface of rubber of the present invention is characterized by containing the following components (A) to (D).

(A) Inorganic component (B) Hydrophobic silicone (C) At least one anionic surfactant selected from the group consisting of (c1) and (c2) below: (c1) Sulfate ester type anionic surfactant (c2) Sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonate salts)
(D) a nonionic surfactant having an HLB value of 7.2 to 11.5 according to the Griffin method

The rubber inner surface release agent of the present invention uses the anionic surfactant of component (C) in combination with the nonionic surfactant of component (D). According to the rubber inner surface release agent of the present invention, for example, the powder (powder) of the inorganic component (A) can be uniformly dispersed in water, and the generation of aggregates can be suppressed or prevented. Therefore, according to the present invention, the adhesion of the aggregates to the rubber surface to which the rubber inner surface release agent is applied can be suppressed or prevented. Therefore, it is possible to suppress or prevent release failure, poor appearance, etc. caused by the aggregates. In addition, according to the rubber inner surface release agent of the present invention, for example, separation of the component (B) (hydrophobic release component) from the surface of the inorganic component (A) (hydrophobic inorganic powder) can be suppressed or prevented. This makes it possible to suppress or prevent the generation of oil spots after application of the rubber inner surface release agent. Therefore, by using the rubber inner surface release agent of the present invention, it is possible to manufacture high-quality rubber products (e.g., tires) in which release failure, poor appearance, etc. are suppressed.

The components of the rubber inner surface release agent of the present invention are not particularly limited and are, for example, as follows:

[1-1. Inorganic component (A)]
The inorganic component (A) (component (A)) is not particularly limited, but may or may not contain mica. Examples of the mica include, but are not particularly limited to, muscovite, sericite, white mica, black mica, phlogopite, illite, and color mica. When component (A) contains mica, it may contain only one type of mica, or two or more types of mica may be used in combination.

When component (A) contains mica, the content of the mica is not particularly limited, but may be, for example, 10 to 50 mass%, 15 to 45 mass%, or 20 to 40 mass% relative to the total mass of the rubber inner surface release agent of the present invention.

The component (A) may or may not contain other inorganic components other than mica. The other inorganic components are not particularly limited, and may be, for example, inorganic components used in general tire inner surface release agents. Examples of the other inorganic components include talc, clay, water-swellable clay minerals, calcium carbonate, zeolite, montmorillonite, beidellite, nontronite, saponite, hectorite, stevensite, bentonite containing montmorillonite, magnesium aluminum silicate, and silicic anhydride, which may be natural or synthetic.

The content of the other inorganic components can be selected according to the purpose, and may be, for example, 20 to 70 mass % or 25 to 65 mass % relative to the total mass of the rubber inner surface release agent of the present invention.

The ratio (W1/W2) of the mass of the mica (W1) in component (A) to the mass of other inorganic components other than the mica (W2) is not particularly limited and may be, for example, 0.1 to 5, 0.1 to 3, or 0.2 to 1.1.

The content of component (A) in the rubber inner surface release agent of the present invention is not particularly limited, but the total mass of component (A) relative to the total mass of the rubber inner surface release agent of the present invention may be, for example, 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, or 50 mass% or more, and may be, for example, 96 mass% or less, 94 mass% or less, 92 mass% or less, 90 mass% or less, or 88 mass% or less.

[1-2. Hydrophobic silicone (B)]
The hydrophobic silicone (B) (component (B)) functions, for example, as a component responsible for improving releasability. Component (B) is not particularly limited, and examples thereof include organopolysiloxanes. The organopolysiloxanes are a concept that includes silicone oils, silicone rubbers, and silicone resins. More specific examples of the organopolysiloxanes include: [1] alkylpolysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, methylisopropylpolysiloxane, and methyldodecylpolysiloxane; [2] alkylphenylpolysiloxanes such as methylphenylpolysiloxane, dimethylsiloxane-methylphenylpolysiloxane copolymer, and dimethylsiloxane-diphenylsiloxane copolymer; [3] alkylaralkylpolysiloxanes such as methyl(phenylethyl)polysiloxane and methyl(phenylpropyl)polysiloxane; and [4] 3,3,3-trifluoropropylmethylpolysiloxane. Among these, silicone oils such as dimethylpolysiloxane and dimethylsilicone oil are preferred. The silicone components may be used alone or in combination of two or more kinds.

The content of component (B) in the rubber inner surface release agent of the present invention is not particularly limited, but the total mass of component (B) relative to the total mass of the rubber inner surface release agent of the present invention may be, for example, 0.1 mass% or more, 1 mass% or more, 3 mass% or more, 5 mass% or more, or 7 mass% or more, and may be, for example, 30 mass% or less, 25 mass% or less, 20 mass% or less, 15 mass% or less, or 12 mass% or less.

[1-3. Anionic surfactant (C)]
The anionic surfactant (C) (component (C)) is, as described above, at least one anionic surfactant selected from the group consisting of (c1) and (c2).

As described above, (c1) is a sulfate ester type anionic surfactant. Although not particularly limited, (c1) may be, for example, at least one selected from the group consisting of alkyl sulfate ester salts, alkenyl sulfate ester salts, polyoxyalkylene alkyl ether sulfate salts, and polyoxyalkylene alkenyl ether sulfate salts, as described above. Although not particularly limited, the alkyl sulfate ester salts include, for example, alkyl sulfate ester salts having 10 to 20 or 12 to 18 carbon atoms, such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium myristyl sulfate, sodium stearyl sulfate, and sodium cetyl sulfate. Although not particularly limited, the alkenyl sulfate ester salts include, for example, alkenyl sulfate ester salts having 10 to 20 or 12 to 18 carbon atoms, such as sodium oleyl sulfate. The polyoxyalkylene alkyl ether sulfate is not particularly limited, but examples thereof include polyoxyalkylene alkyl ether sulfates having an average number of moles of oxyalkylene groups (AO) added of 0 to 4, preferably 0.1 to 3.5, and more preferably 0.3 to 3, and polyoxyethylene alkyl ether sulfates having an average number of moles of oxyalkylene groups (EO) added of 0 to 4, preferably 0.1 to 3.5, and more preferably 0.3 to 3. The polyoxyalkylene alkenyl ether sulfate is not particularly limited, but examples thereof include polyoxyalkylene alkenyl ether sulfates having an average number of moles of oxyalkylene groups (AO) added of 0 to 4, preferably 0.1 to 3.5, and more preferably 0.3 to 3, and polyoxyethylene alkenyl ether sulfates having an average number of moles of oxyalkylene groups (EO) added of 0 to 4, preferably 0.1 to 3.5, and more preferably 0.3 to 3. The number of carbon atoms in the alkyl group of the alkyl sulfate salt and the polyoxyalkylene alkyl ether sulfate salt is preferably 10 to 20, and more preferably 12 to 18. The number of carbon atoms in the alkenyl group of the alkenyl sulfate salt and the polyoxyalkylene alkenyl ether sulfate salt is preferably 10 to 20, and more preferably 12 to 18. The (c1) may contain only one type of sulfate ester-type anionic surfactant, or two or more types may be used in combination.

As described above, (c2) is a sulfonic acid type anionic surfactant other than alkylbenzene sulfonate. Although not particularly limited, (c2) may be, for example, at least one selected from the group consisting of olefin sulfonate, α-sulfofatty acid ester salt, dialkyl sulfosuccinate, and alkyl sulfonate, as described above. Although not particularly limited, the olefin sulfonate may be, for example, α-olefin sulfonate obtained by sulfonating and neutralizing an α-olefin having 12 to 20 carbon atoms, preferably 14 to 18 carbon atoms, or internal olefin sulfonate obtained by sulfonating and neutralizing an internal olefin having 12 to 20 carbon atoms, preferably 14 to 18 carbon atoms. Although not particularly limited, the α-sulfofatty acid ester salt may be, for example, α-sulfofatty acid methyl ester salt having a fatty acid residue with 10 to 18 carbon atoms, preferably 14 to 18 carbon atoms. Although not particularly limited, the dialkyl sulfosuccinate may be, for example, dicetyl sulfosuccinate, dioctyl (2-ethylhexyl) sulfosuccinate, etc.

The ratio (Wc1/Wc2) of the mass (Wc1) of (c1) to the mass (Wc2) of (c2) is not particularly limited and may be, for example, 0 to 5, 0 to 2, 0.0001 to 1.0, 0.0005 to 0.9, 0.00.1 to 0.7, or 0.002 to 0.5.

In the rubber inner surface release agent of the present invention, the anionic surfactant (C) (component (C)) functions, for example, as a component responsible for imparting emulsion stability. The "emulsion stability" refers to the stability of the emulsion when the rubber inner surface release agent aqueous dispersion of the present invention is an emulsion. The emulsion is preferably an emulsion in which the components (A) to (D) are dispersed in water. Such an emulsion is, in other words, an oil-in-water type emulsion. The rubber inner surface release agent aqueous dispersion of the present invention may be a water-in-oil type emulsion, but is preferably an oil-in-water type emulsion from the viewpoints of sprayability, adhesion, release property, etc.

The content of the component (C) in the rubber inner surface release agent of the present invention is not particularly limited, but the total mass of the component (C) relative to the total mass of the rubber inner surface release agent of the present invention may be, for example, 0.1 mass% or more, 0.5 mass% or more, 1.0 mass% or more, or 1.5 mass% or more, and may be, for example, 5.0 mass% or less, 4.0 mass% or less, 3.0 mass% or less, 2.0 mass% or less, 1.5 mass% or less, or 1.0 mass% or less.

[1-4. Nonionic surfactant (D)]
As described above, the nonionic surfactant (D) (component (D)) has an HLB value of 7.2 to 11.5 as determined by the Griffin method.

Here, the HLB according to the Griffin method is a value that can be calculated based on the molecular structure using the following formula (I): That is, the HLB according to the Griffin method can take a value from 0 to 20, with a smaller value (closer to 0) indicating more lipophilicity (hydrophobicity) and a larger value (closer to 20) indicating more hydrophilicity.

HLB = 20 x (sum of formula weights of hydrophilic moieties / molecular weight) (I)

The HLB according to the Griffin method is preferably from 7.5 to 11.3, and more preferably from 7.8 to 11.0.

In the present invention, the nonionic surfactant of component (D) is not particularly limited, but for example, a nonionic surfactant represented by the following chemical formula (1) can be used.

RO-(AO) _n -H (1)

In the chemical formula (1), R is an aliphatic hydrocarbon group, for example, an aliphatic hydrocarbon group having 8 to 22 carbon atoms. The aliphatic hydrocarbon group may be linear or branched. The aliphatic hydrocarbon group may be either a saturated aliphatic hydrocarbon group (alkyl group) or an unsaturated aliphatic hydrocarbon group. From the viewpoint of dispersibility of the hydrophobic component, the number of carbon atoms of R may be, for example, 8 to 22, 8 to 18, 10 to 16, or 12 to 14.
AO represents an oxyalkylene group having 2 to 4 carbon atoms, and n is the average number of moles of AO added.
From the viewpoint of dispersibility of the hydrophobic component, n is, for example, 1 to 50, 1 to 40, 1 to 30, 1 to 25, or 1 to 10.

The oxyalkylene group having 2 to 4 carbon atoms is, for example, a polymerized unit formed by the addition of an alkylene oxide having 2 to 4 carbon atoms (formed by addition polymerization). Specific examples of the oxyalkylene group having 2 to 4 carbon atoms include an oxyethylene group (EO) formed by the addition of ethylene oxide, an oxypropylene group (PO) formed by the addition of propylene oxide, and an oxybutylene group (BO) formed by the addition of butylene oxide. (AO) _n contains at least an oxyethylene group in its structure. When (AO) _n contains a plurality of types of oxyethylene groups (EO), oxypropylene groups (PO), and oxybutylene groups (BO), these groups may be arranged in a block form or randomly. The preferred (AO) _n is composed of only an oxyethylene group (EO) from the viewpoint of excellent balance between hydrophilicity and hydrophobicity.

In addition, when the nonionic surfactant molecule of component (D) is represented by the above chemical formula (1), the hydrophilic portion is the EO portion in (AO) _n . In other words, the sum of the formula weights of the hydrophilic portions represents the sum of the formula weights of the EO portions in (AO) _n . Therefore, when the nonionic surfactant molecule of component (D) is represented by the above chemical formula (1), the HLB according to the Griffin method can be calculated by the following mathematical formula (II).

HLB = 20 × [sum of formula weights of EO moieties in (AO) _n / molecular weight of the chemical formula (1)] (II)

The nonionic surfactant of component (D) may be used alone or in combination of two or more types. When the nonionic surfactant of component (D) is used in combination of two or more types of nonionic surfactants, the HLB value is calculated as a weighted average of the HLB values of each individual component in accordance with the blending composition (weight basis).

The component (D) is not particularly limited, but examples thereof include: [1] polyoxyalkylene alkyl ethers such as polyoxyethylene cetyl ether and polyoxyethylene lauryl ether; [2] polyoxyalkylene alkyl phenyl ethers such as polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether; [3] polyoxyalkylene fatty acid esters such as polyoxyethylene monolaurate and polyoxyethylene monooleate; [4] polyoxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate; [5] polyoxyalkylene hydrogenated castor oil; [6] polyoxyalkylene sorbitol fatty acid esters; [7] polyglycerin fatty acid esters; [8] alkyl glycerin ethers; [9] polyoxyalkylene cholesteryl ethers; [10] alkyl polyglucosides; [11] sucrose fatty acid esters; [12] polyoxyalkylene alkylamines; and [13] oxyethylene-oxypropylene block polymers.

In the rubber inner surface release agent of the present invention, the nonionic surfactant (D) (component (D)) functions as a component responsible for imparting emulsion stability, similar to, for example, the anionic surfactant (C) (component (C)).

The content of component (D) in the rubber inner surface release agent of the present invention is not particularly limited, but the total mass of component (D) relative to the total mass of the rubber inner surface release agent of the present invention may be, for example, 0.1 mass% or more, 0.2 mass% or more, 0.5 mass% or more, or 1 mass% or more, and may be, for example, 18 mass% or less, 15 mass% or less, 12 mass% or less, or 10 mass% or less.

In addition, the rubber inner surface release agent of the present invention may contain, for example, 5 to 5000 parts by mass of the component (D) relative to 100 parts by mass of the component (C), as described above. That is, in the rubber inner surface release agent of the present invention, the mass of the component (D) may be, for example, 5 to 5000% by mass relative to the mass of the component (C). From the viewpoint of water dispersibility, it is preferable that the mass of the component (D) is 5% by mass or more relative to the mass of the component (C). From the viewpoint of suppressing or preventing the occurrence of oil spots, it is preferable that the mass of the component (D) is 5000% by mass or less relative to the mass of the component (C). The mass of the component (D) may be, for example, 6% by mass or more, 10% by mass or more, 20% by mass or more, or 50% by mass or more relative to the mass of the component (C), and may be, for example, 3000% by mass or less, 2000% by mass or less, 1000% by mass or less, or 500% by mass or less.

[1-5. Optional ingredients]
The release agent for the inner surface of a tire of the present invention may or may not contain optional components other than the components (A) to (D). Examples of the optional components include polyhydric alcohols that can contribute to improving transparency, water, various defoaming agents such as silicone-based defoaming agents and mineral oil-based defoaming agents, and various preservatives.

The polyhydric alcohol is not particularly limited, and examples thereof include: [1] polyethylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, and hexaethylene glycol; [2] polypropylene glycols such as dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, and hexapropylene glycol; and [3] polybutylene glycols such as dibutylene glycol, tributylene glycol, tetrabutylene glycol, pentabtylene glycol, and hexabtylene glycol. , [4] ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,2-octanediol, 1,9-nonanediol, 1,2-nonanediol, 1,10-decanediol, 1,2-decanediol, 1,12-dodecanediol, 1,2-dodecanediol, 1,14-tetradecanediol, Decanediol, 1,2-tetradecanediol, 1,16-hexadecanediol, 1,2-hexadecanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-dimethylpentanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, dimethylol octane, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2 ,5-hexanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cycloheptanediol, tricyclodecane dimethanol, glycerin, trimethylolpropane, 1,2,6-hexanetriol, 3-methylpentane-1,3,5-triol, hydroxymethylhexanediol, trimethylol octane, and copolymers of two or more of these. These polyhydric alcohols may be used alone or in combination of two or more.

[2. Method for producing release agent for rubber inner surface]
The method for producing the rubber inner surface release agent of the present invention is not particularly limited. Specifically, for example, all the components of the rubber inner surface release agent of the present invention may be simply mixed. In addition, the rubber inner surface release agent of the present invention may be produced, for example, by the above-mentioned method for producing the rubber inner surface release agent of the present invention.

More specifically, the method for producing the rubber inner surface release agent of the present invention described above can be carried out, for example, as follows.

First, a first mixing step (hereinafter, sometimes referred to as a "pre-mixing step") is performed in which a part of the component (C) and the component (B) are mixed to obtain a mixture. By performing this first mixing step, for example, the affinity between the component (B) (hydrophobic silicone) and the component (A) (inorganic component) is increased, and the effect of suppressing or preventing oil spots is further enhanced. The part of the component (C) used in the first mixing step is not particularly limited, but may be, for example, part or all of the (c2), i.e., sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonate). In the first mixing step, the method of mixing the part of the component (C) and the component (B) is not particularly limited, and may be, for example, stirring and mixing using an emulsifier or the like. The emulsifier is not particularly limited, and may be a general emulsifier, for example, a homomixer, homodisper (both product names), etc. The speed and time of the stirring are not particularly limited, and may be, for example, stirred at 500 to 16,000 rpm (for example, 5,000 rpm) for 0.5 to 20 minutes (for example, 10 minutes). The mixture obtained in the first mixing step is, for example, a silicone emulsion.

Next, a second mixing step is performed in which the remaining part of component (C), component (A), and component (D) are mixed into the mixture obtained in the first mixing step. At this time, optional components other than components (A) to (D) may be further mixed. The optional components are not particularly limited, but are, for example, as described above. The method of performing the second mixing step is not particularly limited, but may be, for example, as follows. That is, first, the mixture obtained in the first mixing step and component (A) are placed in a Henschel mixer and stirred and mixed at 50 to 4000 rpm (for example, 200 rpm) for 3 to 50 minutes (for example, 3 minutes). Furthermore, the remaining part of component (C), component (D), and optional components other than components (A) to (D) as necessary are added to the Henschel mixer, and stirred and mixed for 10 to 30 minutes (for example, 10 minutes) at 100 to 4000 rpm (for example, 600 rpm). There is no particular restriction on the order of addition of the remainder of the component (C), the component (D), and any optional components other than the components (A) to (D). By using a stirring device capable of high speed rotation such as the Henschel mixer, for example, a rubber inner surface release agent having a high bulk density can be obtained. As a stirring device capable of high speed rotation, for example, a Lödige mixer, a high-speed mixer, a Nauter mixer, a Newgra machine, a Schuggi mixer, a Plosser mixer, a Spartan mixer, a Pug mixer, a turbulizer, a horizontal cylindrical mixer, a kneading extruder, a horizontal continuous kneader, a closed type compaction treatment device, etc. may be used instead of the Henschel mixer. In this manner, the rubber inner surface release agent of the present invention can be produced.

In the above-mentioned method for producing a rubber inner surface release agent of the present invention, the Froude number of stirring in stirring after adding all the components may be, for example, 0.5 to 25, or 0.9 to 20. When the Froude number of stirring is 0.5 or more, deterioration of the aqueous dispersion stability and sprayability can be suppressed. Furthermore, when the Froude number of stirring is 25 or less, high equipment costs can be suppressed. The Froude number of stirring (Fr) is, for example, defined by the following formula (1). The product P of the Froude number of stirring and the stirring time (unit: minutes) (i.e., P=Froude number of stirring×stirring time (minutes)) may be, for example, 5 to 200, or 10 to 150.

Fr=V/[(R×g) ^0.5 ] (1)
V: peripheral speed of the tip of the stirring blade (m/s)
R: Rotation radius of the stirring blade (m)
g: Gravitational acceleration (m/s ² )

The average particle size of the produced rubber inner surface release agent may be, for example, 0.1 to 10 mm, or 0.2 to 8 mm. When the average particle size is 0.1 mm or more, deterioration of the aqueous dispersion stability and sprayability can be suppressed. Furthermore, when the average particle size is 10 mm or less, deterioration of the solubility can be suppressed. The average particle size is, for example, a 50% diameter in a cumulative fraction based on mass measured using a sieve method. Specifically, the average particle size is measured by a classification operation using, for example, six-stage sieves with openings of 16000 μm (16 mm), 9500 μm (9.5 mm), 5000 μm (5.0 mm), 1000 μm, 500 μm, and 100 μm (0.10 mm) and a receiving pan. In the classification operation, the sieves are stacked on the tray in the order of smallest mesh size to largest mesh size, 100 g of sample (rubber inner surface release agent) is placed on the top sieve, the sieve is covered and attached to a low tap type sieve shaker (manufactured by Iida Manufacturing Co., Ltd., tapping: 156 times/min, rolling: 290 times/min), and vibrated for 10 minutes, after which the samples (classified samples) remaining on each sieve and on the tray are collected for each sieve. The mass of the classified samples for each particle size is measured, and the mass frequency (%) is calculated. In determining the average particle diameter, the opening of the first sieve with an integrated mass frequency of 50% or more is designated as "a (μm)", the opening of the sieve one step larger than a (μm) is designated as "b (μm)", the integrated value of the mass frequency from the tray to the sieve with opening a (μm) is designated as "c (%)", the mass frequency on the sieve with opening a (μm) is designated as "d (%)", and the average particle diameter (50 mass% particle diameter) determined by the following formula (2) is designated as the average particle diameter.

Average particle size (50% by mass particle size)
=10 ^{[50-{c-d/(logb-loga)×logb}]/{d/(logb-loga)}} (2)

The produced rubber inner surface release agent has a ratio of particles that do not pass through a sieve with a mesh size of 9.5 mm of less than 50% by mass, more preferably less than 30% by mass. The produced rubber inner surface release agent has a ratio of particles that pass through a sieve with a mesh size of 0.10 mm of less than 50% by mass, more preferably less than 30% by mass.

[3. Water dispersion of release agent for rubber inner surface]

The method of using the rubber inner surface release agent of the present invention is not particularly limited, but for example, it can be dispersed in water and used as an aqueous dispersion of the rubber inner surface release agent of the present invention. The form of the aqueous dispersion of the rubber inner surface release agent of the present invention is not particularly limited, but for example, it is preferable that the rubber inner surface release agent of the present invention is an emulsion dispersed in water (aqueous dispersion).

The method for producing (preparing) the aqueous dispersion of the release agent for rubber inner surfaces of the present invention is not particularly limited, and may be, for example, simply by mixing and dispersing the release agent for rubber inner surfaces of the present invention in water. In the aqueous dispersion of the release agent for rubber inner surfaces of the present invention, the concentration of the release agent for rubber inner surfaces of the present invention is not particularly limited, and may be, for example, 20 to 75% by mass, 30 to 70% by mass, or 30 to 65% by mass.

The method of using the rubber inner surface release agent of the present invention is not particularly limited, and may be the same as that of a general rubber inner surface release agent. Specifically, for example, the rubber inner surface release agent aqueous dispersion of the present invention may be applied to at least one of the inner surface of the rubber (e.g., raw rubber made of unvulcanized rubber) and the outer surface of the bladder using a spray.

As described above, the aqueous dispersion of the release agent for rubber inner surfaces of the present invention may be an emulsion. The average particle diameter of the emulsion is not particularly limited and may be, for example, 50 to 2000 nm, 100 to 1500 nm, or 150 to 1300 nm. From the viewpoint of preventing a decrease in adhesion and a decrease in release properties due to an increase in the required amount of surfactant, and from the viewpoint of preventing adhesion inhibition when the release agent gets into the bonding part, the average particle diameter of the emulsion is preferably 50 nm or more. In addition, from the viewpoint of preventing creaming and coalescence of the emulsion particles, and from the viewpoint of preventing separation of the water-soluble component and the oil-soluble component, which causes poor product stability, the average particle diameter of the emulsion is preferably 2000 nm or less. In the present invention, the average particle diameter of the emulsion can be calculated based on the volume distribution of the emulsion particles measured using, for example, a submicron particle analyzer (laser diffraction/scattering method) manufactured by BECKMAN. However, this measurement method is merely an example, and the present invention is not limited to this measurement method.

[4. Manufacturing method of rubber product, manufacturing method of tire, rubber product and tire]
The manufacturing method of the rubber product, the manufacturing method of the tire, the rubber product, and the tire of the present invention are as described above. There is no particular limitation on these. For example, the manufacturing method of the rubber product of the present invention can be carried out in the same manner as the manufacturing method of a general rubber product, except that the rubber inner surface release agent or the rubber inner surface release agent aqueous dispersion of the present invention is used instead of the general rubber inner surface release agent or the rubber inner surface release agent aqueous dispersion of the general rubber inner surface release agent. In addition, the manufacturing method of the tire of the present invention can be carried out in the same manner as the manufacturing method of a general tire, except that the tire inner surface release agent or the tire inner surface release agent aqueous dispersion of the general tire inner surface release agent or the tire inner surface release agent aqueous dispersion of the general tire inner surface release agent or the tire inner surface release agent aqueous dispersion of the general tire inner surface release agent. In the manufacturing method of the tire of the present invention, the molding die can be, for example, a metal mold. In addition to the above-mentioned peeling pretreatment step and vulcanization step, the manufacturing method of the tire of the present invention may have a release treatment step of performing a release treatment between the vulcanized tire and the bladder, and between the vulcanized tire and the molding die.

Below, examples of the present invention are described. However, the present invention is not limited to the following examples.

The rubber inner surface release agents of Examples 1 to 12 and Comparative Examples 1 to 6 were produced as follows, and their properties were evaluated.

[Method of manufacturing the release agent for rubber inner surface]
The rubber inner surface release agents of Examples 1 to 12 and Comparative Examples 1 to 6 were produced using the components (raw materials) shown in Tables 1 and 2 in the mass ratios (weight ratios) shown in Tables 1 and 2. The product names (product names), manufacturers, and characteristics (properties) of the components (raw materials) shown in Tables 1 and 2 are shown in Table 3. The raw material symbols in Tables 1 and 2 correspond to those in Table 3.

Specifically, the rubber inner surface release agents of Examples 1 to 12 and Comparative Examples 1 to 6 were manufactured as follows. First, component (B) shown in Table 1 or 2 below and the anionic surfactant (part of component (C)) shown in Table 1 or 2 below as "premixing step" were mixed by stirring at 5000 rpm for 10 minutes in a homomixer (product name) to perform the first mixing step (premixing step). In this way, a silicone emulsion (silicone emulsion), which is a mixture of a part of component (C) and component (B), was obtained. Next, the second mixing step was performed. That is, first, the silicone emulsion obtained in the first mixing step (premixing step) and component (A) were placed in a Henschel mixer and stirred at 200 rpm for 3 minutes to mix. Furthermore, component (C), component (D) and other components (optional components) were added to the Henschel mixer in sequence while stirring, and then further stirred and mixed at 600 rpm for 10 minutes. In this manner, powdery release agents for the inner surface of a tire of Examples 1 to 12 and Comparative Examples 1 to 6 were produced.

[Method of producing aqueous dispersion of release agent for rubber inner surface]
450 g of tap water was placed in a 2 L glass beaker, and then stirred at a speed of 20 rpm with a stirrer equipped with three propeller blades with a diameter of 5 cm. 550 g of the powdered tire inner surface release agent produced in each Example or Comparative Example was added to the water while stirring, and stirred for 30 minutes to disperse the agent, thereby producing an aqueous dispersion of the rubber inner surface release agent of each Example or Comparative Example.

[Evaluation method]
The properties of particulate matter (aggregates), oil spots, and releasability were evaluated for each of the aqueous dispersions of rubber inner surface release agents of the Examples and Comparative Examples by the following methods.

(Water dispersibility, granular matter evaluation)
The rubber release agent aqueous dispersion (tire inner surface release agent treatment liquid) of each of the above-mentioned Examples or Comparative Examples was continuously sprayed for 10 seconds on the surface of an unvulcanized inner liner rubber sheet (brominated butyl rubber, which is a bromine adduct of isobutylene-isoprene copolymer) measuring 4 cm x 7 cm x 0.2 cm, using a spray gun with a nozzle diameter of φ1.0 mm, at an air pressure of 0.5 MPa, and the spray-coated surface was visually judged after drying within a range of 4 cm x 7 cm. Specifically, after drying, the presence or absence of granular matter (aggregates) on the spray-coated surface was evaluated according to the following criteria, and grade 3 or higher was judged as passing. Note that when the conditions of multiple grades were met simultaneously, it was evaluated as corresponding to the lowest grade (the grade with the smallest number).

Oil spot criteria:
Grade 5: 5 or less granules with a major axis of less than 1 mm, and no granules with a major axis of 1 mm or more Grade 4: 6 to 10 granules with a major axis of less than 1 mm, and no granules with a major axis of 1 mm or more Grade 3: 1 to 5 granules with a major axis of 1 mm or more, or 11 to 20 granules with a major axis of 1 mm or more Grade 2: 6 to 20 granules with a major axis of 1 mm or more, or 21 or more granules with a major axis of 1 mm or more Grade 1: 21 or more granules with a major axis of 1 mm or more

(Water dispersion stability, oil spot evaluation)
The rubber release agent aqueous dispersion (tire inner surface release agent treatment liquid) of each of the above-mentioned Examples or Comparative Examples was continuously sprayed for 10 seconds on the surface of an unvulcanized inner liner rubber sheet (brominated butyl rubber, which is a bromine adduct of isobutylene-isoprene copolymer) measuring 4 cm x 7 cm x 0.2 cm, using a spray gun with a nozzle diameter of φ1.0 mm, at an air pressure of 0.5 MPa, and the spray-coated surface was visually judged after drying within a range of 4 cm x 7 cm. Specifically, after drying, the presence or absence of oil spots (oil droplets) on the spray-coated surface was evaluated according to the following judgment criteria, and grade 3 or higher was judged as passing. Note that when the conditions of multiple grades were met simultaneously, it was evaluated as corresponding to the lowest grade (the grade with the smallest number).

Oil spot criteria:
Grade 5: 5 or less oil spots with a major axis of less than 1 mm, and no oil spots with a major axis of 1 mm or more Grade 4: 6 to 10 oil spots with a major axis of less than 1 mm, and no oil spots with a major axis of 1 mm or more Grade 3: 1 to 5 oil spots with a major axis of 1 mm or more, or 11 to 20 oil spots with a major axis of 1 mm or more Grade 2: 6 to 20 oil spots with a major axis of 1 mm or more, or 21 or more oil spots with a major axis of 1 mm or more Grade 1: 21 or more oil spots with a major axis of 1 mm or more

(Mold releasability)
The rubber release agent aqueous dispersion (tire inner surface release agent treatment liquid) of each of the above-mentioned Examples or Comparative Examples was spray-coated on the surface of an unvulcanized inner liner rubber sheet (brominated butyl rubber, which is a bromine adduct of isobutylene-isoprene copolymer) measuring 4 cm x 7 cm x ^0.2 cm so that the coating amount after drying would be 10 g/ ^m2 , and then further dried. Next, a bladder rubber sheet of the same size was placed on top of this unvulcanized rubber sheet, and the sheet was set in a tabletop test press machine and pressed for 20 minutes at a mold temperature of 180°C and a pressure of 20 kg/cm2 to be vulcanized. Thereafter, the vulcanized rubber sheet was peeled off. The peelability (releasability) was evaluated as follows: grade 5 for easy peeling (releasability) without adhesion, grade 4 for peeling (releasability), grade 3 for peeling resistance but possible, grade 2 for partial adhesion and difficult peeling (releasability), and grade 1 for full adhesion and impossible peeling (releasability).

As shown in Table 1, the rubber inner surface release agents of Examples 1 to 12 contained all of components (A) to (D). In contrast, as shown in Table 2, none of Comparative Examples 1 to 6 contained (c1), which is a part of component (C). That is, none of Comparative Examples 1 to 6 contained component (C). Furthermore, Comparative Example 1 did not contain component (D) (nonionic surfactant). Comparative Example 2 did not contain any anionic surfactant. Comparative Example 3 added linear alkyl (C12-C14) sodium benzenesulfonate (LAS) in the second mixing step. Comparative Example 4 used a nonionic surfactant with a high HLB (greater than 11.5) according to the Griffin method instead of component (D). Comparative Examples 5 and 6 used a nonionic surfactant with a low HLB (less than 7.2) according to the Griffin method instead of component (D).

As shown in Table 1, the rubber inner surface release agents of Examples 1 to 12 had a small amount of particulate matter (aggregates), and therefore all of the evaluation results for water dispersibility (particulate matter) were grade 3 or higher, which was acceptable. In addition, the rubber inner surface release agents of Examples 1 to 12 had excellent evaluation results for dispersion stability (oil spots) of grade 3 or higher (grade 3 or higher is acceptable). Furthermore, the rubber inner surface release agents of Examples 1 to 12 had extremely excellent release properties of grade 5. That is, all of the rubber inner surface release agents of Examples 1 to 12 were able to simultaneously suppress or prevent the occurrence of aggregates and suppress or prevent the occurrence of oil spots after application, and had excellent release properties. In contrast, as shown in Table 2, all of the rubber inner surface release agents of Comparative Examples 1 to 6 had evaluation results of at least one of water dispersibility (particulate matter) and dispersion stability (oil spots) of grade 2 or lower, which was unacceptable. That is, the rubber inner surface release agents of Comparative Examples 1 to 6 could not simultaneously suppress or prevent the generation of aggregates and suppress or prevent the generation of oil spots after application. In addition, Comparative Example 2 had extremely poor release properties of grade 1.

This application claims priority based on Japanese Patent Application No. 2020-028667, filed on February 21, 2020, the disclosure of which is incorporated herein in its entirety.

Claims (9)

Contains the following components (A) to (D):
The content of the following component (A) in the rubber inner surface release agent is 50 to 90 % by mass based on the total mass of the rubber inner surface release agent,
The content of the following component (B) in the rubber inner surface release agent is 3 to 25% by mass of the total mass of the rubber inner surface release agent,
The content of the following component (C) in the rubber inner surface release agent is 0.5 to 5.5% by mass of the total mass of the rubber inner surface release agent,
The content of the following component (D) in the rubber inner surface release agent is 0.1 to 15 mass % of the total mass of the rubber inner surface release agent.

(A) an inorganic component including mica; (B) a hydrophobic silicone; and (C) at least one anionic surfactant selected from the group consisting of the following (c1) and (c2): (c1) a sulfate ester type anionic surfactant; and (c2) a sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonates).
(D) a nonionic surfactant having an HLB value according to the Griffin method of 7.2 to 11.5,
The nonionic surfactant is represented by the following chemical formula (1):

RO-(AO) _n -H (1)

R is an aliphatic hydrocarbon group having 8 to 22 carbon atoms,
The AO is an oxyalkylene group having 2 to 4 carbon atoms,
The n is the average number of moles of the AO added,
The n is 1 to 10. The rubber inner surface release agent according to claim 1, wherein the AO is an oxyethylene group having 2 carbon atoms. the (c1) is at least one selected from the group consisting of alkyl sulfates, alkenyl sulfates, polyoxyalkylene alkyl ether sulfates, and polyoxyalkylene alkenyl ether sulfates;
The (c2) is at least one selected from the group consisting of olefin sulfonate, α-sulfofatty acid ester salt, and dialkyl sulfosuccinate.
The release agent for the inner surface of rubber according to claim 1 or 2. The release agent for rubber inner surfaces according to any one of claims 1 to 3, containing 5 to 1000 parts by mass of component (D) per 100 parts by mass of component (C). The rubber inner surface release agent according to any one of claims 1 to 4, which is a tire inner surface release agent. a first mixing step of mixing a part or all of the component (c2) with the component (B) to obtain a mixture;
a second mixing step of mixing the remainder of the component (C), the component (A), and the component (D) with the mixture obtained in the first mixing step;
6. A method for producing the release agent for the inner surface of rubber according to claim 1, comprising the steps of: An aqueous dispersion of a rubber inner surface release agent, comprising the rubber inner surface release agent according to any one of claims 1 to 5 and water. A method for producing a rubber product, comprising the steps of directly or indirectly applying the aqueous dispersion of a release agent for rubber inner surfaces described in claim 7 to the inner surface of the rubber, and further comprising a pretreatment step for release in which the water is volatilized. a pretreatment step for release in which an aqueous dispersion of a release agent for an inner surface of a tire, the aqueous dispersion containing the release agent for an inner surface of a rubber according to claim 5 and water, is applied to at least one of an inner surface of a raw tire made of unvulcanized rubber and an outer surface of a bladder, and the water is then volatilized;
a vulcanization step in which, after the pretreatment step for mold release, the bladder housed in the raw tire in a molding die is expanded to press an outer surface of the raw tire against an inner surface of the molding die, and the raw tire is heated and vulcanized in this state;
A method for producing a tire, comprising: