Release agent for rubber inner surface, method for producing release agent for rubber inner surface, aqueous dispersion of release agent for rubber inner surface, method for producing rubber product, method for producing tire, rubber product and tire

Abstract

The purpose of the present invention is to provide a rubber-inner-surface release agent that is capable of achieving both suppression or prevention of the occurrence of aggregates and suppression or prevention of the occurrence of oil spots after application.　In order to achieve the above-described purpose, the rubber-inner-surface release agent according to the present invention is characterized by containing the following components (A) to (D). (A) an inorganic component; (B) a hydrophobic silicone; (C) at least one kind of anionic surfactant selected from the group consisting of (c1) sulfuric-acid ester-type anionic surfactants and (c2) sulfonic-acid-type anionic surfactants (excluding alkylbenzene sulfonate); and (D) a nonionic surfactant of which the HLB value according to the Griffin method falls within the range from 7.2 to 11.5.

Description

Technical Field

[0001] The present invention relates to a mold release agent for rubber inner surfaces, a method for producing a mold release agent for rubber inner surfaces, an aqueous dispersion of a mold release agent for rubber inner surfaces, a method for producing rubber products, a method for producing tires, rubber products, and tires.

Background Art

[0002] As a kind of mold release agent for rubber, there is a mold release agent for tire inner surfaces. For example, Patent Document 1 describes a mold release agent for tire inner surfaces containing an inorganic component (inorganic powder) composed of powder, a silicone component, a surfactant, a polyhydric alcohol, and water.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The mold release agent for tire inner surfaces is used, for example, as follows. That is, in the tire manufacturing process, in the vulcanization molding of an unvulcanized green tire, a rubber bag called a bladder is placed inside the unvulcanized green tire, and the bladder is inflated with warm air, hot water, or steam to press the unvulcanized green tire against the inside of the mold, and vulcanization is performed together with press-fitting molding. In order to perform this process smoothly, a mold release agent for tire inner surfaces is pre-sprayed (inside paint) on the inner liner surface (inner surface) of the green tire. Therefore, in order to reduce the tire defect rate in the manufacturing process and keep the product appearance good, it is important to keep the state of the spray-coated surface uniform.

[0005] For the inside paint, for example, a mold release agent for the inner surface of a tire (a mold release agent for the rubber inner surface) having a structure in which the surface of a hydrophobic inorganic powder is coated with a hydrophobic mold release component is used as in Patent Document 1. In this case, due to the aggregation of hydrophobic inorganic powders during powder production or during aqueous dispersion, water dispersion defects occur, aggregates are generated on the spray-coated surface, which may cause an increase in the tire defect rate and deterioration of the product appearance. In order to suppress or prevent the generation of such aggregates (dispersion defects), for example, it is conceivable to add a dispersant to the mold release agent for rubber interior.

[0006] On the other hand, the mold release agent for the rubber inner surface is generally stored and used in the state of an aqueous dispersion. If an excessive amount of dispersant is added to the mold release agent for the rubber inner surface in order to suppress or prevent the generation of aggregates (dispersion defects), there is a risk that the hydrophobic mold release component may peel off from the surface of the hydrophobic inorganic powder. That is, excessive addition of the dispersant may reduce the dispersion stability of the aqueous dispersion of the mold release agent for the rubber inner surface. And when the hydrophobic mold release component peels off from the surface of the hydrophobic inorganic powder, oil spots may occur after spray coating of the mold release agent for the rubber inner surface, which may cause appearance defects.

[0007] As described above, in the mold release agent for the rubber inner surface, it is difficult to achieve both suppression or prevention of the generation of aggregates and suppression or prevention of the generation of oil spots after coating.

[0008] Therefore, an object of the present invention is to provide a mold release agent for the rubber inner surface, a method for producing a mold release agent for the rubber inner surface, an aqueous dispersion of a mold release agent for the rubber inner surface, a method for producing a rubber product, a method for producing a tire, a rubber product, and a tire, which can achieve both suppression or prevention of the generation of aggregates and suppression or prevention of the generation of oil spots after coating.

Means for Solving the Problems

[0009] In order to achieve the above object, the mold release agent for the rubber inner surface of the present invention is characterized by containing the following components (A) to (D). (A) Inorganic component (B) Hydrophobic silicone (C) At least one type of anionic surfactant selected from the group consisting of the following (c1) and (c2) (c1) Sulfate ester type anionic surfactant (c2) Sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonate) (D) Nonionic surfactant with an HLB of 7.2 to 11.5 by the Griffin method

[0010] The method for producing the release agent for the rubber inner surface of the present invention is a method for producing the release agent for the rubber inner surface of the present invention, A first mixing step of mixing a part of the component (C) and the component (B) to obtain a mixture, A second mixing step of mixing the remaining part of the component (C), the component (A), and the component (D) with the mixture obtained in the first mixing step, characterized by including

[0011] The aqueous dispersion of the release agent for the rubber inner surface of the present invention is characterized by including the release agent for the rubber inner surface of the present invention and water.

[0012] The method for producing a rubber product of the present invention is characterized by including a pre-treatment step for release in which the aqueous dispersion of the release agent for the rubber inner surface of the present invention is directly or indirectly adhered to the inner surface of the rubber and then water is volatilized.

[0013] The method for producing a tire of the present invention is A pre-treatment step for release in which an aqueous dispersion of the release agent for the tire inner surface, which contains the release agent for the rubber inner surface of the present invention and water, is adhered to at least one of the inner surface of the unvulcanized rubber green tire and the outer surface of the bladder, and then water is volatilized, After the pre-treatment step for release, the bladder housed in the green tire is inflated in a mold to press the outer surface of the green tire against the inner surface of the mold, and in that state, the green tire is heated and vulcanized in a vulcanization step, characterized by including

[0014] The rubber product of the present invention is characterized in that the mold release agent for the rubber inner surface of the present invention adheres to the rubber inner surface.

[0015] The first tire of the present invention is characterized in that the mold release agent for the rubber inner surface of the present invention, which is a mold release agent for the tire inner surface, adheres to the inner surface of the tire.

[0016] The second tire of the present invention is characterized in that the mold release agent for the rubber inner surface of the present invention, which is a mold release agent for the tire inner surface, is adhered to the inner surface of the green 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".

Advantages of the Invention

[0017] According to the present invention, it is possible to provide a mold release agent for a rubber inner surface, a method for producing a mold release agent for a rubber inner surface, an aqueous dispersion of a mold release agent for a rubber inner surface, a method for producing a rubber product, a method for producing a tire, a rubber product, and a tire that can achieve both suppression or prevention of the generation of aggregates and suppression or prevention of the generation of oil spots after coating.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described more specifically. However, the present invention is not limited by the following description.

[0019] The mold release agent for the rubber inner surface of the present invention is, for example, wherein (c1) is at least one selected from the group consisting of alkyl sulfates, alkenyl sulfates, polyoxyalkylene alkyl ether sulfates, and polyoxyalkylene alkenyl ether sulfates, and (c2) may be at least one selected from the group consisting of olefin sulfonates, α-sulfo fatty acid esters, and dialkyl sulfosuccinates.

[0020] The mold release agent for the rubber inner surface of the present invention may contain, for example, 5 to 1000 parts by mass of the component (D) with respect to 100 parts by mass of the component (C).

[0021] The mold release agent for the rubber inner surface of the present invention may be, for example, a mold release agent for the inner surface of a tire. In the following, the mold release agent for the rubber inner surface of the present invention, which is a mold release agent for the inner surface of a tire, may be referred to as "the mold release agent for the inner surface of a tire of the present invention".

[0022] [1. Mold release agent for rubber inner surface] The mold release agent for the rubber inner surface of the present invention is characterized by containing the following components (A) to (D) as described above. (A) Inorganic component (B) Hydrophobic silicone (C) At least one anionic surfactant selected from the group consisting of the following (c1) and (c2) (c1) Sulfate ester type anionic surfactant (c2) Sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonate) (D) Nonionic surfactant having an HLB of 7.2 to 11.5 by the Griffin method

[0023] The mold release agent for the rubber inner surface of the present invention uses the anionic surfactant of the component (C) and the nonionic surfactant of the component (D) in combination. According to the mold release agent for the rubber inner surface of the present invention, for example, it is possible to uniformly disperse the powder (powder body) of the inorganic component (A) 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 coated with the mold release agent for the rubber inner surface can be suppressed or prevented. For this reason, it is possible to suppress or prevent mold release failure, appearance defects, etc. caused by the aggregates. Further, according to the mold release agent for the rubber inner surface of the present invention, for example, the separation of the component (B) (hydrophobic mold release component) from the surface of the inorganic component (A) (hydrophobic inorganic powder) can be suppressed or prevented. Thereby, the generation of oil spots after applying the mold release agent for the rubber inner surface can be suppressed or prevented. Therefore, by using the mold release agent for the rubber inner surface of the present invention, for example, it is possible to manufacture high-quality rubber products (for example, tires) with suppressed mold release failure, appearance defects, etc.

[0024] Each component in the mold release agent for the rubber inner surface of the present invention is not particularly limited and is, for example, as follows.

[0025] [1-1. Inorganic component (A)] The inorganic component (A) (component (A)) is not particularly limited. For example, it may or may not contain mica. The mica is not particularly limited, and examples thereof include muscovite, sericite, white mica, biotite, phlogopite, illite, colored mica, etc. When the component (A) contains mica, it may contain only one type of mica, or two or more types of mica may be used in combination.

[0026] When the component (A) contains mica, the content of the mica is not particularly limited, but is, for example, 10 to 50% by mass, 15 to 45% by mass, or 20 to 40% by mass with respect to the total mass of the mold release agent for the rubber inner surface of the present invention.

[0027] Further, 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, stibbsite, bentonite containing montmorillonite, magnesium aluminum silicate, anhydrous silicic acid, etc. These may be natural products or synthetic products.

[0028] The content rate of the other inorganic components can be selected according to the purpose. For example, it may be 20 to 70% by mass, or 25 to 65% by mass, based on the total mass of the rubber inner surface release agent of the present invention.

[0029] The ratio (W1 / W2) of the mass (W1) of the mica in the component (A) to the mass (W2) of the other inorganic components other than the mica is not particularly limited and may be, for example, 0.1 to 5, 0.1 to 3, or 0.2 to 1.1.

[0030] The content rate of the component (A) in the rubber inner surface release agent of the present invention is not particularly limited, but the total mass of the component (A) may be, for example, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, based on the total mass of the rubber inner surface release agent of the present invention, and may be, for example, 96% by mass or less, 94% by mass or less, 92% by mass or less, 90% by mass or less, or 88% by mass or less.

[0031] [1-2. Hydrophobic silicone (B)] The hydrophobic silicone (B) (component (B)) functions, for example, as a component responsible for improving mold release properties. Component (B) is not particularly limited, and examples thereof include organopolysiloxanes. The organopolysiloxanes are a concept including silicone oils, silicone rubbers, and silicone resins. More specifically, 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 them, silicone oils such as dimethylpolysiloxane and dimethyl silicone oil are preferred. The silicone component may be used alone or in combination of a plurality of types.

[0032] The content of the component (B) in the mold release agent for the rubber inner surface of the present invention is not particularly limited, but the total mass of the component (B) may be, for example, 0.1% by mass or more, 1% by mass or more, 3% by mass or more, 5% by mass or more, or 7% by mass or more, and may be, for example, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 12% by mass or less, based on the total mass of the mold release agent for the rubber inner surface of the present invention.

[0033] [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 the above (c1) and (c2).

[0034] As described above, (c1) is a sulfate-type anionic surfactant. Although (c1) is not particularly limited, for example, as described above, it may be at least one selected from the group consisting of alkyl sulfate salts, alkenyl sulfate salts, polyoxyalkylene alkyl ether sulfates, and polyoxyalkylene alkenyl ether sulfates. The alkyl sulfate salt is not particularly limited, and examples thereof include alkyl sulfate salts having 10 to 20 carbon atoms or 12 to 18 carbon atoms such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium myristyl sulfate, sodium stearyl sulfate, and sodium cetyl sulfate. The alkenyl sulfate salt is not particularly limited, and examples thereof include alkenyl sulfate salts having 10 to 20 carbon atoms or 12 to 18 carbon atoms such as sodium oleyl sulfate. The polyoxyalkylene alkyl ether sulfate is not particularly limited, and examples thereof include polyoxyalkylene alkyl ether sulfates in which the average number of added moles of an oxyalkylene group (AO) is 0 to 4, preferably 0.1 to 3.5, and more preferably 0.3 to 3, and polyoxyethylene alkyl ether sulfates in which the average number of added moles of an oxyethylene group (EO) is 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, and examples thereof include polyoxyalkylene alkenyl ether sulfates in which the average number of added moles of an oxyalkylene group (AO) is 0 to 4, preferably 0.1 to 3.5, and more preferably 0.3 to 3, and polyoxyethylene alkenyl ether sulfates in which the average number of added moles of an oxyethylene group (EO) is 0 to 4, preferably 0.1 to 3.5, and more preferably 0.3 to 3. The number of carbon atoms of the alkyl group of the alkyl sulfate salt and the polyoxyalkylene alkyl ether sulfate is preferably 10 to 20, and more preferably 12 to 18. The number of carbon atoms of the alkenyl group of the alkenyl sulfate salt and the polyoxyalkylene alkenyl ether sulfate is preferably 10 to 20, and more preferably 12 to 18. (c1) may contain only one type of sulfate-type anionic surfactant, or two or more types may be used in combination.

[0035] As described above, (c2) is a sulfonic acid type anionic surfactant excluding alkylbenzene sulfonate. (c2) is not particularly limited, and for example, as described above, it may be at least one selected from the group consisting of olefin sulfonate, α-sulfo fatty acid ester salt, and dialkyl sulfosuccinate, alkyl sulfonate. The olefin sulfonate is not particularly limited, and 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, and internal olefin sulfonate obtained by sulfonating and neutralizing an internal olefin having 12 to 20 carbon atoms, preferably 14 to 18 carbon atoms, etc. may be mentioned. The α-sulfo fatty acid ester salt is not particularly limited, and for example, α-sulfo fatty acid methyl ester salt in which the carbon number of the fatty acid residue is 10 to 18, preferably 14 to 18, etc. may be mentioned. The dialkyl sulfosuccinate is not particularly limited, and for example, dodecyl sulfosuccinate, dioctyl (2-ethylhexyl) sulfosuccinate, etc. may be mentioned.

[0036] The ratio (Wc1 / Wc2) of the mass (Wc1) of (c1) to the mass (Wc2) of (c2) is not particularly limited, and for example, it may be 0 to 5, 0 to 2, 0.0001 to 1.0, 0.0005 to 0.9, 0.001 to 0.7, or 0.002 to 0.5.

[0037] In the release agent for the rubber inner surface 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 aqueous dispersion of the release agent for the rubber inner surface 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, that is, an oil-in-water type emulsion (emulsion). The aqueous dispersion of the release agent for the rubber inner surface of the present invention may be a water-in-oil type emulsion, but from the viewpoints of sprayability, adhesiveness, releasability, etc., it is preferably an oil-in-water type emulsion.

[0038] The content rate of the component (C) in the mold release agent for the rubber inner surface of the present invention is not particularly limited. However, with respect to the total mass of the mold release agent for the rubber inner surface of the present invention, the total mass of the component (C) may be, for example, 0.1% by mass or more, 0.5% by mass or more, 1.0% by mass or more, or 1.5% by mass or more, and may be, for example, 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0039] [1-4. Nonionic surfactant (D)] The nonionic surfactant (D) (component (D)) has an HLB of 7.2 to 11.5 by the Griffin method as described above.

[0040] Here, the HLB by the Griffin method is a numerical value that can be calculated by the following mathematical formula (I) based on the molecular structure. That is, the HLB by the Griffin method can take a numerical value from 0 to 20, and the smaller the numerical value (closer to 0), the more lipophilic (hydrophobic), and the larger the numerical value (closer to 20), the more hydrophilic, serving as an index. HLB = 20 × (sum of formula weights of hydrophilic parts / molecular weight) (I) The HLB by the Griffin method is preferably 7.5 to 11.3, more preferably 7.8 to 11.0.

[0041] In the present invention, the nonionic surfactant of the component (D) is not particularly limited. For example, a nonionic surfactant represented by the following chemical formula (1) can be used. RO-(AO) n -H (1)

[0042] In the above 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. Further, the aliphatic hydrocarbon group may be either a saturated aliphatic hydrocarbon group (alkyl group) or an unsaturated aliphatic hydrocarbon group. From the viewpoint of the dispersibility of the hydrophobic component, the number of carbon atoms in 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 addition of AO. From the viewpoint of the 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.

[0043] The oxyalkylene group having 2 to 4 carbon atoms is, for example, a polymer 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. (AO) n When (AO) contains a plurality of types among an oxyethylene group (EO), an oxypropylene group (PO), and an oxybutylene group (BO), these groups may be arranged in a block form or randomly. Preferred (AO) n consists only of an oxyethylene group (EO) from the viewpoint of excellent balance between hydrophilicity and hydrophobicity.

[0044] Further, when the nonionic surfactant molecule of component (D) is represented by the above chemical formula (1), the hydrophilic part thereof is the EO part in (AO). That is, the total sum of the formula weights of the hydrophilic part represents the total sum of the formula weights of the EO part in (AO). Therefore, when the nonionic surfactant molecule of component (D) is represented by the above chemical formula (1), the HLB by the Griffin method can be calculated by the following mathematical formula (II). n Among them, it becomes the EO part. That is, the total sum of the formula weights of the hydrophilic part represents the total sum of the formula weights of the EO part in (AO). n Therefore, when the nonionic surfactant molecule of component (D) is represented by the above chemical formula (1), the HLB by the Griffin method can be calculated by the following mathematical formula (II). HLB = 20 × [(AO) n in the sum of the molecular weights of the EO moieties in / the molecular weight of the chemical formula (1)] (II)

[0045] Also, as the nonionic surfactant of component (D), only one type may be used, or two or more types may be used in combination. When two or more types of nonionic surfactants of component (D) are used in combination, the HLB value shall be calculated as a weighted average according to the blending composition (by weight) of the HLB values of the individual components.

[0046] Component (D) is not particularly limited. For example, [1] polyoxyalkylene alkyl ethers such as polyoxyethylene cetyl ether and polyoxyethylene lauryl ether, [2] polyoxyalkylene alkyl phenyl ethers such as polyoxyethylene nonyl phenyl ether and polyoxyethylene octyl phenyl 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] polyglycerol fatty acid esters, [8] alkyl glycerol ethers, [9] polyoxyalkylene cholesteryl ethers,

[10] alkyl polyglucosides,

[11] sucrose fatty acid esters,

[12] polyoxyalkylene alkyl amines,

[13] oxyethylene-oxypropylene block polymers, etc. may be mentioned.

[0047] In the release agent for the rubber inner surface of the present invention, the nonionic surfactant (D) (component (D)) functions as a component responsible for imparting emulsion stability, similar to the anionic surfactant (C) (component (C)).

[0048] The content of the component (D) in the mold release agent for the rubber inner surface of the present invention is not particularly limited. However, based on the total mass of the mold release agent for the rubber inner surface of the present invention, the total mass of the component (D) may be, for example, 0.1% by mass or more, 0.2% by mass or more, 0.5% by mass or more, or 1% by mass or more, and may be, for example, 18% by mass or less, 15% by mass or less, 12% by mass or less, or 10% by mass or less.

[0049] Also, the mold release agent for the rubber inner surface of the present invention may contain, for example, as described above, 5 to 5000 parts by mass of the component (D) with respect to 100 parts by mass of the component (C). That is, in the mold release agent for the rubber inner surface of the present invention, the mass of the component (D) may be, for example, 5 to 5000% by mass with respect 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 with respect 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 with respect 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 with respect 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.

[0050] [1-5. Optional Components] The mold release agent for the tire inner surface 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 antifoaming agents such as silicone-based antifoaming agents and mineral oil-based antifoaming agents, and various preservatives.

[0051] The polyhydric alcohol is not particularly limited. For example, [1] polyethylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, etc.; [2] polypropylene glycols such as dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, hexapropylene glycol, etc.; [3] polybutylene glycols such as dibutylene glycol, tributylene glycol, tetrabutylene glycol, pentabutylene glycol, hexabutylene glycol, etc.; [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, 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, dimethyloctane, 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, tricyclodecanedimethanol, glycerin, trimethylolpropane, 1,2,Examples thereof include 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 kinds.,

[0052] [2. Method for producing release agent for rubber inner surface] The method for producing the release agent for rubber inner surface of the present invention is not particularly limited. Specifically, for example, all components of the release agent for rubber inner surface of the present invention may be simply mixed. Further, the release agent for rubber inner surface of the present invention may be produced, for example, by the method for producing the release agent for rubber inner surface of the present invention described above.,

[0053] More specifically, the method for producing the release agent for rubber inner surface of the present invention described above can be carried out, for example, as follows.,

[0054] First, a first mixing step (hereinafter, may also be referred to as a "preliminary mixing step") of mixing a part of the component (C) and the component (B) to obtain a mixture is performed. 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. A part of the component (C) used in the first mixing step is not particularly limited, but for example, a part or all of the (c2), that is, the sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonate) may be used. In the first mixing step, the method of mixing a part of the component (C) and the component (B) is not particularly limited, and for example, it may be stirred and mixed using an emulsifier or the like. The emulsifier is not particularly limited, and a general emulsifier may be used, and examples thereof include a homomixer and a homodisper (both are trade names). The stirring speed and time are also not particularly limited, but for example, it may be stirred at 500 to 16000 rpm (for example, 5000 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.,

[0055] Next, a second mixing step is performed in which the remainder of the component (C), the component (A), and the component (D) are mixed with the mixture obtained in the first mixing step. At this time, an optional component other than the components (A) to (D) may be further mixed. The optional component is not particularly limited, but is, 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 the 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). Further, the remainder of the component (C), the component (D), and, if necessary, an optional component other than the components (A) to (D) are added to the Henschel mixer and stirred and mixed at 100 to 4000 rpm (for example, 600 rpm) for 10 to 30 minutes (for example, 10 minutes). There is no particular limitation on the order of addition of the remainder of the component (C), the component (D), and the optional component 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 mold release agent for a rubber inner surface having a high bulk density can be obtained. As the stirring device capable of high-speed rotation, instead of the Henschel mixer, for example, a Lodige mixer, a high-speed mixer, a Nauta mixer, a New Gramachine, a Sugimixer, a Proshear mixer, a Spartan mixer, a Pug mixer, a Turbulizer, a horizontal cylindrical mixer, a kneading extruder, a horizontal continuous kneader, a closed compaction treatment device, etc. may be used. As described above, the mold release agent for a rubber inner surface of the present invention can be produced.

[0056] In the method for producing the mold release agent for the rubber inner surface of the present invention described above, the agitation Froude number in the agitation after adding all the components may be, for example, 0.5 to 25, or 0.9 to 20. When the agitation Froude number is 0.5 or more, deterioration of the water dispersion stability and sprayability can be suppressed. Also, when the agitation Froude number is 25 or less, high equipment costs can be suppressed. The agitation Froude number (Fr) is defined by, for example, the following formula (1). The product P of the agitation Froude number and the agitation time (unit: minutes) (that is, P = agitation Froude number × agitation 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 agitation blade (m / s) R: Rotation radius of the agitation blade (m) g: Acceleration due to gravity (m / s 2 )

[0057] The average particle diameter of the manufactured release agent for the rubber inner surface may be, for example, 0.1 to 10 mm, or 0.2 to 8 mm. When the average particle diameter is 0.1 mm or more, deterioration of the water dispersion stability and sprayability can be suppressed. Also, when the average particle diameter is 10 mm or less, deterioration of the solubility can be suppressed. The average particle diameter is, for example, the 50% diameter in the cumulative fraction on a mass basis measured using a sieve method. Specifically, the average particle diameter is measured, for example, by a classification operation using six sieves with mesh 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 tray. In the classification operation, the receiving tray is stacked in order from the sieve with the smallest mesh opening to the sieve with the largest mesh opening, and a 100 g / sample (release agent for the rubber inner surface) is placed from above the top sieve, covered, and attached to a rotary tap type sieve shaker (manufactured by Iida Seisakusho Co., Ltd., tapping: 156 times / min, rolling: 290 times / min), and after vibrating for 10 minutes, the samples (classified samples) remaining on each sieve and on the receiving tray are collected for each sieve opening. The mass of the classified samples for each particle diameter is measured, and the mass frequency (%) is calculated. When obtaining the average particle diameter, the mesh opening of the first sieve at which the cumulative mass frequency becomes 50% or more is defined as "a (μm)", the mesh opening of the sieve one step larger than a (μm) is defined as "b (μm)", the integrated value of the mass frequency from the receiving tray to the sieve with mesh opening a (μm) is defined as "c (%)", the mass frequency on the sieve with mesh opening a (μm) is defined as "d (%)", and the average particle diameter (50 mass% particle diameter) obtained by the following formula (2) is taken as the average particle diameter. Average particle diameter (50 mass% particle diameter) = 10 [50-{c-d / (logb-loga)×logb}] / {d / (logb-loga)} (2) It is preferable that the proportion of particles that do not pass through a sieve with a mesh opening of 9.5 mm in the manufactured release agent for the rubber inner surface is less than 50% by mass, and more preferably less than 30% by mass. Also, it is preferable that the proportion of particles that pass through a sieve with a mesh opening of 0.10 mm in the manufactured release agent for the rubber inner surface is less than 50% by mass, and more preferably less than 30% by mass.

[0058] [Release agent aqueous dispersion for rubber inner surface, etc.]

[0059] The method of using the release agent for the rubber inner surface of the present invention is not particularly limited. For example, it can be dispersed in water and used as the aqueous dispersion of the release agent for the rubber inner surface of the present invention. The form of the aqueous dispersion of the release agent for the rubber inner surface of the present invention is not particularly limited. For example, it is preferable that the release agent for the rubber inner surface of the present invention is an emulsion (aqueous dispersion) dispersed in water.

[0060] The method for producing (preparing) the aqueous dispersion of the release agent for the rubber inner surface of the present invention is also not particularly limited. For example, it is only necessary to mix and disperse the release agent for the rubber inner surface of the present invention in water. In the aqueous dispersion of the release agent for the rubber inner surface of the present invention, the concentration of the release agent for the rubber inner surface of the present invention is not particularly limited. For example, it may be 20 to 75% by mass, 30 to 70% by mass, or 30 to 65% by mass.

[0061] The method of using the release agent for the rubber inner surface of the present invention is also not particularly limited. For example, it may be the same as that of a general release agent for the rubber inner surface. Specifically, for example, the aqueous dispersion of the release agent for the rubber inner surface of the present invention may be applied to at least one of the inner surface of the rubber (for example, raw rubber made of unvulcanized rubber) and the outer surface of the bladder using a spray.

[0062] As described above, the mold release agent aqueous dispersion for the rubber inner surface of the present invention may be an emulsion. The average particle size 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 viewpoints of preventing a decrease in adhesiveness and mold release property due to an increase in the required blending amount of the surfactant, and preventing inhibition of adhesion when the mold release agent enters the bonding portion, the average particle size of the emulsion is preferably 50 nm or more. Further, from the viewpoints of preventing creaming and coalescence of the emulsion particles, and preventing separation of the water-soluble component and the oil-soluble component and deterioration of product stability, the average particle size of the emulsion is preferably 2000 nm or less. In the present invention, the average particle size of the emulsion can be calculated, for example, by measuring the volume distribution of the emulsion particles using a submicron particle analyzer (laser diffraction / scattering method) manufactured by BECKMAN and based on the measured volume distribution of the emulsion particles. However, this measurement method is merely an example, and the present invention is not limited by this measurement method.

[0063] [4. Method for manufacturing rubber products, method for manufacturing tires, rubber products and tires] The method for manufacturing rubber products of the present invention, the method for manufacturing tires, rubber products and tires are as described above. There are also no particular limitations on these. For example, the method for manufacturing rubber products of the present invention can be carried out in the same manner as the general method for manufacturing rubber products, except that the mold release agent for the rubber inner surface or the mold release agent aqueous dispersion for the rubber inner surface of the present invention is used instead of a general mold release agent for the rubber inner surface or a mold release agent aqueous dispersion for the rubber inner surface. Further, the method for manufacturing tires of the present invention can be carried out in the same manner as the general method for manufacturing tires, except that the mold release agent for the tire inner surface or the mold release agent aqueous dispersion for the tire inner surface of the present invention is used instead of a general mold release agent for the tire inner surface or a mold release agent aqueous dispersion for the tire inner surface. In the method for manufacturing tires of the present invention, examples of the molding die include a metal die and the like. The method for manufacturing tires of the present invention may have a mold release treatment step for performing a mold release treatment between the vulcanized tire and the bladder, and between the vulcanized tire and the molding die, in addition to the above-described pretreatment step for peeling and the vulcanization step.

Example

[0064] Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the following examples.

[0065] The mold release agents for rubber inner surfaces of Examples 1 to 12 and Comparative Examples 1 to 6 were produced as follows, and their properties were further evaluated.

[0066] [Method for Producing Mold Release Agent for Rubber Inner Surface] The mold release agents for rubber inner surfaces of Examples 1 to 12 and Comparative Examples 1 to 6 were produced using the respective components (raw materials) shown in Tables 1 and 2 below in the mass ratios (weight ratios) shown in Tables 1 and 2 below. The product names (trade names), manufacturers, and characteristics of the respective components (raw materials) shown in Tables 1 and 2 below are shown in Table 3 below. The raw material symbols in Tables 1 and 2 below correspond to the raw material symbols in Table 3 below.

[0067] The production of the mold release agents for rubber inner surfaces of Examples 1 to 12 and Comparative Examples 1 to 6 was specifically carried out as follows. First, component (B) described in Table 1 or 2 below and the anionic surfactant (part of component (C)) described as the "preliminary mixing step" in Table 1 or 2 below were stirred and mixed at 5000 rpm for 10 minutes using a homomixer (trade name) to perform the first mixing step (preliminary mixing step). Thus, a silicone emulsion (silicone emulsion), which is a mixture of part of component (C) and component (B), was obtained. Next, a second mixing step was performed. That is, first, the silicone emulsion obtained by the first mixing step (preliminary mixing step) and component (A) were put into a Henschel mixer and stirred and mixed at 200 rpm for 3 minutes. Further, component (C), component (D), and other components (optional components) were sequentially added to the Henschel mixer while stirring, and then stirred and mixed at 600 rpm for 10 minutes. As described above, the powdery mold release agents for tire inner surfaces of Examples 1 to 12 and Comparative Examples 1 to 6 were produced.

[0068] [Method for Producing Aqueous Dispersion of Mold Release Agent for Rubber Inner Surface] After charging 450 g of tap water into a 2 L glass beaker, it was stirred at a speed of 20 rpm with a stirrer equipped with three propeller blades having a diameter of 5 cm. While stirring in the water, 550 g of the powdery mold release agent for the inner surface of the tire produced in each example or comparative example was added, and it was stirred for 30 minutes to disperse it, thereby producing a mold release agent aqueous dispersion for the rubber inner surface of each example or comparative example.

[0069] [Evaluation method] By the following method, for the mold release agent aqueous dispersion for the rubber inner surface of each example or comparative example, the characteristics of particulate matter (aggregate), oil spot, and mold release property were evaluated respectively.

[0070] (Water dispersibility, particulate matter evaluation) The mold release agent aqueous dispersion for rubber (tire inner surface mold release agent treatment liquid) of each example or comparative example was continuously sprayed onto the surface of an unvulcanized inner liner rubber sheet (brominated butyl rubber which is a brominated adduct of isobutylene isoprene copolymer) of 4 cm × 7 cm × 0.2 cm for 10 seconds using a spray gun with a nozzle diameter of φ1.0 mm at an air pressure of 0.5 MPa. After drying, it was visually judged within a range of 4 cm × 7 cm of the spray coating surface. Specifically, after drying, the presence or absence of particulate matter (aggregate) on the spray coating surface was evaluated according to the following judgment criteria, and a grade of 3 or higher was judged as qualified. In addition, when the conditions of multiple grades were satisfied simultaneously, it was evaluated as corresponding to the lowest grade (the grade with the smallest number). Oil spot judgment criteria: Grade 5: Five or less particulate matters with a major axis of less than 1 mm and no particulate matter with a major axis of 1 mm or more Grade 4: Six or more and ten or less particulate matters with a major axis of less than 1 mm and no particulate matter with a major axis of 1 mm or more Grade 3: One or more and five or less particulate matters with a major axis of 1 mm or more, or eleven or more and twenty or less particulate matters with a major axis of 1 mm or more Grade 2: Six or more and twenty or less particulate matters with a major axis of 1 mm or more, or twenty-one or more particulate matters with a major axis of 1 mm or more Grade 1: Twenty-one or more particulate matters with a major axis of 1 mm or more

[0071] (Water dispersion stability, oil spot evaluation) The rubber release agent aqueous dispersion (tire inner surface release agent treatment liquid) of each of the above examples or comparative examples was continuously sprayed onto the surface of an unvulcanized inner liner rubber sheet (brominated butyl rubber, which is a brominated adduct of an isobutylene isoprene copolymer) of 4 cm × 7 cm × 0.2 cm for 10 seconds using a spray gun with a nozzle diameter of φ1.0 mm and an air pressure of 0.5 MPa. After drying, visual inspection was carried out within the range of the spray application surface of 4 cm × 7 cm. Specifically, after drying, the presence or absence of oil spots (oil droplets) on the spray application surface was evaluated according to the following evaluation criteria, and a grade of 3 or higher was determined to be qualified. In addition, when the conditions of multiple grades were satisfied simultaneously, it was evaluated as corresponding to the lowest grade (the grade with the smallest number). Oil spot evaluation criteria: Grade 5: Five or fewer 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: Six to ten 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: One to five oil spots with a major axis of 1 mm or more, or eleven to twenty oil spots with a major axis of 1 mm or more Grade 2: Six to twenty oil spots with a major axis of 1 mm or more, or twenty-one or more oil spots with a major axis of 1 mm or more Grade 1: Twenty-one or more oil spots with a major axis of 1 mm or more

[0072] (Release property) The rubber release agent aqueous dispersion (tire inner surface release agent treatment liquid) of each of the above examples or comparative examples was spray-coated onto the surface of an unvulcanized inner liner rubber sheet (brominated butyl rubber, which is a brominated adduct of an isobutylene isoprene copolymer) of 4 cm × 7 cm × 0.2 cm so that the coating amount after drying was 10 g / m 2 and then further dried. Next, a bladder rubber sheet of the same size was overlaid on this unvulcanized rubber sheet, set in a tabletop test press, and the mold temperature was 180 °C and the pressure was 20 kg / cm 2It was pressurized for 20 minutes and vulcanized. After that, the vulcanized rubber sheet was peeled off. The peelability (release property) was evaluated as follows: grade 5 for those that could be easily peeled off (released) without adhesion, grade 4 for those that could be peeled off (released), grade 3 for those with high peel resistance but could be released, grade 2 for those with partial adhesion and difficult to peel off (release), and grade 1 for those with full adhesion and impossible to peel off (release).

[0073]

Table 1

[0074]

Table 2

[0075]

Table 3

[0076] As shown in Table 1 above, the release agents for the rubber inner surface in Examples 1 to 12 all contained components (A) to (D). In contrast, as shown in Table 2 above, Comparative Examples 1 to 6 did not contain (c1), which is a part of component (C). That is, Comparative Examples 1 to 6 did not contain component (C) at all. Also, Comparative Example 1 did not contain component (D) (nonionic surfactant). Comparative Example 2 did not contain any anionic surfactant. Comparative Example 3 added sodium linear alkyl (C12 - C14) benzene sulfonate (LAS) in the second mixing step. Comparative Example 4 used a nonionic surfactant with a high HLB (exceeding 11.5) by the Griffin method instead of component (D). Comparative Examples 5 and 6 used nonionic surfactants with a low HLB (less than 7.2) by the Griffin method instead of component (D).

[0077] As shown in Table 1 above, for the mold release agents for the rubber inner surface in Examples 1 to 12, since there were few granular substances (aggregates), the evaluation results of water dispersibility (granular substances) were all qualified at Grade 3 or above. Also, for the mold release agents for the rubber inner surface in Examples 1 to 12, the evaluation results of dispersion stability (oil spots) were all excellent at Grade 3 or above (Grade 3 or above is considered qualified). Furthermore, the mold release agents for the rubber inner surface in Examples 1 to 12 all had a mold release property of Grade 5 and were extremely excellent. That is, the mold release agents for the rubber inner surface in Examples 1 to 12 were all capable of achieving both the suppression or prevention of the generation of aggregates and the suppression or prevention of the generation of oil spots after coating, and had excellent mold release properties. In contrast, as shown in Table 2 above, for the mold release agents for the rubber inner surface in Comparative Examples 1 to 6, the evaluation results of at least one of water dispersibility (granular substances) and dispersion stability (oil spots) were unqualified at Grade 2 or below. That is, the mold release agents for the rubber inner surface in Comparative Examples 1 to 6 were unable to achieve both the suppression or prevention of the generation of aggregates and the suppression or prevention of the generation of oil spots after coating. Also, in Comparative Example 2, the mold release property was extremely poor at Grade 1.

[0078] This application claims the priority based on Japanese Patent Application No. 2020-028667 filed on February 21, 2020, and incorporates all of its disclosures herein.

Claims

1. Comprising the following components (A) to (D), The content rate of the following component (A) in the following mold release agent for rubber inner surface is such that the total mass of the following component (A) is 50 to 90% by mass with respect to the total mass of the following mold release agent for rubber inner surface, The content rate of the following component (B) in the following mold release agent for rubber inner surface is such that the total mass of the following component (B) is 3 to 25% by mass with respect to the total mass of the following mold release agent for rubber inner surface, The content rate of the following component (C) in the following mold release agent for rubber inner surface is such that the total mass of the following component (C) is 0.5 to 5.5% by mass with respect to the total mass of the following mold release agent for rubber inner surface, The content rate of the following component (D) in the following mold release agent for rubber inner surface is such that the total mass of the following component (D) is 0.1 to 15% by mass with respect to the total mass of the following mold release agent for rubber inner surface A mold release agent for rubber inner surface, characterized by the above. (A) Inorganic component containing mica (B) Hydrophobic silicone (C) At least one kind of anionic surfactant selected from the group consisting of the following (c1) and (c2) (c1) Sulfate ester type anionic surfactant (c2) Sulfonic acid type anionic surfactant (excluding alkylbenzene sulfonate) (D) A nonionic surfactant having an HLB of 7.2 to 11.5 by the Griffin method, The nonionic surfactant is represented by the following chemical formula (1), RO-(AO) ｎ -H (1) The 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 addition of the AO, The n is 1 to 10

2. The mold release agent for rubber inner surface according to Claim 1, wherein the AO is an oxyethylene group having 2 carbon atoms.

3. The (c1) is at least one kind selected from the group consisting of alkyl sulfate ester salts, alkenyl sulfate ester salts, polyoxyalkylene alkyl ether sulfates, and polyoxyalkylene alkenyl ether sulfates, The (c2) is at least one kind selected from the group consisting of olefin sulfonates, α-sulfo fatty acid ester salts, and dialkyl sulfosuccinates, The mold release agent for rubber inner surface according to Claim 1 or 2.

4. The mold release agent for rubber inner surface according to any one of Claims 1 to 3, containing 5 to 1000 parts by mass of the component (D) with respect to 100 parts by mass of the component (C).

5. The mold release agent for rubber inner surface according to any one of Claims 1 to 4, which is a mold release agent for tire inner surface.

6. A first mixing step of mixing part or all of the component (c2) and the component (B) to obtain a mixture; A second mixing step of mixing the remaining part of the component (C), the component (A), and the component (D) into the mixture obtained in the first mixing step; A method for producing a release agent for rubber inner surface according to any one of claims 1 to 5, characterized by comprising the above.

7. A release agent aqueous dispersion for rubber inner surface, characterized by comprising the release agent for rubber inner surface according to any one of claims 1 to 5 and water.

8. A method for producing a rubber product, characterized by comprising a pre-treatment step for release, in which the release agent aqueous dispersion for rubber inner surface according to claim 7 is directly or indirectly adhered to the rubber inner surface, and then water is volatilized.

9. A pre-treatment step for release, in which a release agent aqueous dispersion for tire inner surface containing the release agent for rubber inner surface according to claim 5 and water is adhered to at least one of the inner surface of an unvulcanized rubber green tire and the outer surface of a bladder, and then water is volatilized; A vulcanization step of expanding the bladder housed in the green tire in a mold after the pre-treatment step for release, thereby pressing the outer surface of the green tire against the inner surface of the mold, and heating and vulcanizing the green tire in that state; A method for producing a tire, characterized by comprising the above.

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