JP6735650B2 - Refurbished tire manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a retreaded tire in which a tread rubber is attached to a base tire via an adhesive cushion rubber.

A pneumatic tire basically has a structure in which a tread rubber that is in contact with the road surface is attached to a base tire. The tread rubber has a limited useful life because it wears as the tire runs for a long period of time, but it is often possible to use the tread rubber sufficiently even after the life of the tread rubber ends. Therefore, the worn tread rubber portion may be covered with a new tread rubber and used again as a retreaded tire. As tires for automobiles, particularly heavy-duty tires for trucks or buses, retreaded tires are often used to reduce tire costs.

In the manufacture of retreaded tires, there are two major categories: a remolding method in which unvulcanized tread rubber is attached to the base tire, and a tread pattern is applied to the tread rubber while being put in a mold and vulcanized. The vulcanized tread rubber (precure tread) with is attached to the base tire to form a precure tread attachment base tire, which is attached to the rim-shaped body and the annular vulcanization envelope is attached. There are two types: a pre-cure method in which the pre-cure tread sticking base tire is covered and vulcanized in a vulcanizing can.

Regardless of which method is used, vulcanization of retreaded tires is performed at a relatively low temperature for a long time, so that the cushion rubber that bonds the tread rubber and the base tire shrinks during vulcanization, causing wrinkles, etc. May result in non-uniform adhesion.

JP, 2014-95014, A

In addition, in the said patent document 1, although the rubber composition for treads which mix|blended the specific compound for the purpose of improving fuel efficiency is described, the description and suggestion of the said subject concerning cushion rubber are also made. Not not.

The present invention has been made in view of the above circumstances, and an object thereof is to improve the shape stability of a cushion rubber for adhering a tread rubber and a base tire, thereby producing a retreaded tire having improved adhesiveness between the two. To provide.

（式（Ｉ）中、Ｒ^１およびＲ^２は、水素原子、ならびに炭素数１〜２０のアルキル基、アルケニル基またはアルキニル基を示し、Ｒ^１およびＲ^２は同一であっても異なっていてもよい。Ｍ^＋はナトリウムイオン、カリウムイオンまたはリチウムイオンを示す。）を添加し、水分を含んだ前記充填材含有ゴム凝固物中で前記式（Ｉ）に記載の化合物を分散させつつ、前記充填材含有ゴム凝固物を脱水する工程であることを特徴とする更生タイヤの製造方法、に関する。 The above object can be achieved by the present invention as described below. That is, the present invention is a method for manufacturing a retreaded tire in which a tread rubber is attached to a base tire through a cushion rubber for adhesion, wherein the step of manufacturing the cushion rubber includes a filler, a dispersion solvent, and a rubber latex solution. Mixing (i) to produce a filler-containing rubber latex solution, coagulating the filler-containing rubber latex solution to produce a filler-containing rubber solidified product (ii), the filler-containing rubber coagulation A step (iii) of producing a rubber wet masterbatch by dehydrating the product, and a step (iv) of molding a rubber composition containing the rubber wet masterbatch into a sheet, the step (iii) Is a compound represented by the following formula (I) in the filler-containing rubber solidified product:

(In the formula (I), R ¹ and R ² represent a hydrogen atom and an alkyl group, an alkenyl group or an alkynyl group having 1 to 20 carbon atoms, and R ¹ and R ² may be the same or different. M ⁺ represents sodium ion, potassium ion or lithium ion), and the compound of formula (I) is dispersed in the filler-containing rubber coagulated product containing water, and the filling is performed. The present invention relates to a method for manufacturing a retreaded tire, which comprises a step of dehydrating a material-containing rubber solidified product.

The above-mentioned manufacturing method is particularly characterized by the step of manufacturing cushion rubber. Specifically, in the above-mentioned production method, in the step (iii) of the cushion rubber production step, the compound of the above formula (I) is dispersed in the filler-containing rubber coagulated product containing water while the filler-containing compound is contained. Dewater the rubber coagulum. Generally, the rubber used for tires is hydrophobic in the dry state. On the other hand, since the compound represented by the above formula (I) exhibits hydrophilicity, even if the dry rubber and the compound represented by the formula (I) are dry-mixed, the dispersibility of the compound represented by the formula (I) is improved. Does not improve. However, in the above-mentioned production method, in the step (iii) corresponding to the dehydration step, the compound of the formula (I) is dispersed in the filler-containing rubber coagulated product containing water, so that the compound of formula (I The dispersibility of the compound described in (1) is dramatically increased. As a result, the compound of formula (I) is dispersed at a high level in the filler-containing rubber coagulum. Once the compound of the formula (I) is dispersed in the filler-containing rubber coagulum, the dispersibility of the compound of the formula (I) is maintained even if the filler-containing rubber coagulum is dehydrated. Therefore, even in the finally obtained rubber wet masterbatch and the rubber composition thereof, the dispersibility of the compound represented by the formula (I) is improved. Further, since the compound represented by the formula (I) is blended, shrinkage of the cushion rubber obtained by vulcanization is suppressed, and shape stability is improved. As a result, the retreaded tire including such cushion rubber has excellent adhesion between the tread rubber and the base tire.

In the method for producing a retreaded tire, in the step (iii), the water content of the filler-containing rubber coagulum at the time of adding the compound described in the formula (I) is Wa, and the compound described in the formula (I) is When the addition amount is Wb, it is preferable that 1≦Wa/Wb≦8100. As described above, the compound represented by the formula (I) has remarkably improved dispersibility in the filler-containing rubber solidified product through the presence of water. In particular, when 1≦Wa/Wb≦8100, the dispersibility of the compound represented by the formula (I) and the shortening of the time required for removing water in the filler-containing rubber solidified product can be achieved in a well-balanced manner.

（式（Ｉ）中、Ｒ^１およびＲ^２は、水素原子、ならびに炭素数１〜２０のアルキル基、アルケニル基またはアルキニル基を示し、Ｒ^１およびＲ^２は同一であっても異なっていてもよい。Ｍ^＋はナトリウムイオン、カリウムイオンまたはリチウムイオンを示す。）および水分を添加し、分散させることを特徴とする更生タイヤの製造方法、に関する。 Furthermore, the present invention is a method for producing a retreaded tire in which a tread rubber is attached to a base tire via a cushion rubber for adhesion, wherein the cushion rubber production step is performed for a mixture of a filler and rubber as follows. Compounds of formula (I):

(In the formula (I), R ¹ and R ² represent a hydrogen atom and an alkyl group, an alkenyl group or an alkynyl group having 1 to 20 carbon atoms, and R ¹ and R ² may be the same or different. M ⁺ represents sodium ion, potassium ion or lithium ion) and water to disperse and disperse the retreaded tire.

In the above production method, the compound represented by the above formula (I) is dispersed in the mixture of the filler and the rubber in the presence of water. Generally, the rubber used for tires is hydrophobic in the dry state. On the other hand, since the compound represented by the above formula (I) exhibits hydrophilicity, even if the dry rubber and the compound represented by the formula (I) are dry-mixed, the dispersibility of the compound represented by the formula (I) is improved. Does not improve. However, in the above production method, since the compound represented by the above formula (I) is dispersed in the mixture of the filler and the rubber in the presence of water, the dispersibility of the compound represented by the formula (I) is remarkably increased via water. Increase to. As a result, the compound of formula (I) is dispersed at a high level in the mixture of filler and rubber. Once the compound of the formula (I) is dispersed in the filler-containing rubber coagulum, the dispersibility of the compound of the formula (I) is maintained even if the filler-containing rubber coagulum is dehydrated. Therefore, even in the finally obtained rubber wet masterbatch and the rubber composition thereof, the dispersibility of the compound represented by the formula (I) is improved. Further, since the compound represented by the formula (I) is blended, shrinkage of the cushion rubber obtained by vulcanization is suppressed, and shape stability is improved. As a result, the retreaded tire including such cushion rubber has excellent adhesion between the tread rubber and the base tire.

In the method for manufacturing a retreaded tire, it is preferable that 1≦Wa/Wb≦8100, where Wa is the amount of water added and Wb is the amount of the compound represented by the formula (I). As described above, the compound represented by the formula (I) has a markedly improved dispersibility in the mixture of the filler and the rubber through the presence of water. Particularly, when 1≦Wa/Wb≦7500, the dispersibility of the compound represented by the formula (I) and the shortening of the time required for removing water in the mixture of the filler and the rubber can be achieved in a well-balanced manner.

In the method for manufacturing a retreaded tire according to the present invention, at least the filler, the dispersion solvent, and the rubber latex solution are used as raw materials in the cushion rubber manufacturing process.

In the present invention, the filler means an inorganic filler usually used in the rubber industry such as carbon black, silica, clay, talc, calcium carbonate, magnesium carbonate and aluminum hydroxide. Among the above-mentioned inorganic fillers, carbon black can be particularly preferably used in the present invention.

As the carbon black, for example, SAF, ISAF, HAF, FEF, GPF, and the like used in the usual rubber industry, as well as conductive carbon black such as acetylene black and Ketjen black can be used. The carbon black may be a granulated carbon black or a non-granulated carbon black granulated in consideration of its handling property in a usual rubber industry.

As the dispersion solvent, it is particularly preferable to use water, but water containing an organic solvent may be used.

As the rubber latex solution, a natural rubber latex solution and a synthetic rubber latex solution can be used.

The natural rubber latex solution is a natural product of the metabolic action of plants, and is preferably a natural rubber/water system in which the dispersion solvent is water. The number average molecular weight of the natural rubber in the natural rubber latex used in the present invention is preferably 2,000,000 or more, more preferably 2.5,000,000 or more. Concentrated latex and fresh latex called field latex can be used for natural rubber latex solution without distinction. Examples of the synthetic rubber latex solution include those prepared by emulsion polymerization of styrene-butadiene rubber, butadiene rubber, nitrile rubber, and chloroprene rubber.

（式（Ｉ）中、Ｒ^１およびＲ^２は、水素原子、ならびに炭素数１〜２０のアルキル基、アルケニル基またはアルキニル基を示し、Ｒ^１およびＲ^２は同一であっても異なっていてもよい。Ｍ^＋はナトリウムイオン、カリウムイオンまたはリチウムイオンを示す。） In the method for manufacturing a retreaded tire according to the present invention, in the cushion rubber manufacturing step, when at least the filler, the dispersion solvent, and the rubber latex solution obtained by using the rubber latex solution as a raw material are dehydrated, the following formula (I ).

(In the formula (I), R ¹ and R ² represent a hydrogen atom and an alkyl group, an alkenyl group or an alkynyl group having 1 to 20 carbon atoms, and R ¹ and R ² may be the same or different. Good. M ⁺ represents sodium ion, potassium ion or lithium ion.)

を使用することが特に好ましい。 In order to increase the affinity for the filler, particularly carbon black, R ¹ and R ² in the formula (I) are hydrogen atoms and M ⁺ is a sodium ion. Listed compounds:

Is particularly preferably used.

In order to improve the shape stability of the cushion rubber, when the total amount of the rubber component contained in the tire member is 100 parts by mass, the compounding amount of the compound represented by the formula (I) is 0.1 to 10 parts by mass. It is preferable that the amount is 0.5 to 5 parts by mass.

Of the method for manufacturing a retreaded tire according to the present invention, the cushion rubber manufacturing process will be specifically described below. The manufacturing process includes a step (i) of manufacturing a filler-containing rubber latex solution by mixing a filler, a dispersion solvent, and a rubber latex solution, coagulating the filler-containing rubber latex solution, and filling the filler-containing rubber latex solution. A step (ii) of producing a coagulated product, a step (iii) of producing a rubber wet masterbatch by dehydrating the filler-containing rubber coagulated product, and a rubber composition containing the rubber wet masterbatch in a sheet form A step (iv) of molding, wherein the step (iii) comprises adding the compound represented by the formula (I) to the filler-containing rubber coagulum, and in the filler-containing rubber coagulum containing water, It is a step of dehydrating the filler-containing rubber solidified product while dispersing the compound represented by the formula (I).

(1) Step (i)
In step (i), the filler, the dispersion solvent, and the rubber latex solution are mixed to produce a filler-containing rubber latex solution. Particularly, in the present invention, in the step (i), at the time of dispersing the filler in the dispersion solvent, at least a part of the rubber latex solution is added to the filler to which the rubber latex particles are attached. A step (i-(a)) of producing a slurry solution containing a material, and a slurry solution containing the filler to which the rubber latex particles are attached, and the remaining rubber latex solution are mixed to form rubber latex particles. It is preferable to include a step (i-(b)) of producing the filler-containing rubber latex solution to which is attached. The step (i-(a)) and the step (i-(b)) will be described below. Particularly, in this embodiment, an example in which carbon black is used as a filler will be described.

Step (i-(a))
In the step (i-(a)), when carbon black is dispersed in a dispersion solvent, at least a part of the rubber latex solution is added to produce a slurry solution containing carbon black to which rubber latex particles are attached. To do. The rubber latex solution may be mixed with a dispersion solvent in advance, and then carbon black may be added and dispersed. Further, carbon black may be added to the dispersion solvent, and then the carbon latex may be dispersed in the dispersion solvent while adding the rubber latex solution at a predetermined addition rate, or the carbon black may be added to the dispersion solvent. Then, the carbon black may be dispersed in the dispersion solvent while adding a certain amount of the rubber latex solution in several batches. By dispersing carbon black in a dispersion solvent in the presence of the rubber latex solution, it is possible to produce a slurry solution containing the carbon black to which the rubber latex particles are attached. The amount of the rubber latex solution added in the step (i-(a)) is based on the total amount of the rubber latex solution used (the total amount added in the step (i-(a)) and the step (i-(b))). Thus, 0.075 to 12 mass% is exemplified.

In the step (i-(a)), the amount of solid content (rubber) of the rubber latex solution to be added is preferably 0.25 to 15% by mass ratio with carbon black, and 0.5 to 6%. It is preferable to have. The solid content (rubber) concentration in the rubber latex solution to be added is preferably 0.2 to 5% by mass, and more preferably 0.25 to 1.5% by mass. In these cases, it is possible to manufacture the rubber wet masterbatch in which the dispersion degree of the carbon black is enhanced while surely adhering the rubber latex particles to the carbon black.

In the step (i-(a)), as a method of mixing the carbon black and the dispersion solvent in the presence of the rubber latex solution, a high shear mixer, a high shear mixer, a homomixer, a ball mill, a bead mill, a high pressure homogenizer, an ultrasonic homogenizer, There is a method of dispersing carbon black using a general disperser such as a colloid mill.

The "high shear mixer" is a mixer including a rotor and a stator, and the rotor rotates with a precise clearance provided between the rotor capable of high-speed rotation and a fixed stator. Means a mixer with a high shear action. In order to generate such a high shearing action, it is preferable that the clearance between the rotor and the stator is 0.8 mm or less and the peripheral speed of the rotor is 5 m/s or more. As such a high shear mixer, a commercially available product can be used, and examples thereof include "High Shear Mixer" manufactured by SILVERSON.

In the present invention, carbon black and a dispersion solvent are mixed in the presence of a rubber latex solution to produce a slurry solution containing carbon black having rubber latex particles adhered, and a surfactant for improving dispersibility of carbon black. May be added. As the surface active agent, a surface active agent known in the rubber industry can be used, and examples thereof include a nonionic surface active agent, an anionic surface active agent, a cationic surface active agent, and a zwitterionic surface active agent. To be Further, alcohol such as ethanol may be used instead of the surfactant or in addition to the surfactant. However, when a surfactant is used, it is feared that the rubber physical properties of the final vulcanized rubber may be deteriorated. Therefore, the compounding amount of the surfactant is 100 parts by mass of the solid content (rubber) of the rubber latex solution. On the other hand, it is preferably 2 parts by mass or less, more preferably 1 part by mass or less, and it is preferable that substantially no surfactant is used.

Process (i-(b))
In the step (i-(b)), the slurry solution and the remaining rubber latex solution are mixed to produce a carbon black-containing rubber latex solution having rubber latex particles attached thereto. The method of mixing the slurry solution and the remaining rubber latex solution in the liquid phase is not particularly limited, and the slurry solution and the remaining rubber latex solution are mixed with a high shear mixer, a high shear mixer, a homomixer, a ball mill, a bead mill. , A high-pressure homogenizer, an ultrasonic homogenizer, a colloid mill, and other general dispersing machines may be used for mixing. If necessary, the entire mixing system such as a disperser may be heated during mixing.

Considering the dehydration time and labor in the next step (iii), the remaining rubber latex solution preferably has a higher solid content (rubber) concentration than the rubber latex solution added in step (i-(a)). Specifically, the solid content (rubber) concentration is preferably 10 to 60% by mass, and more preferably 20 to 30% by mass.

(2) Step (ii)
In the step (ii), the filler-containing rubber latex solution is coagulated to produce a filler-containing rubber coagulated product. Examples of the coagulation method include a method in which a coagulant is contained in a filler-containing rubber latex solution to which rubber latex particles are attached. In this case, as the coagulant, acids such as formic acid and sulfuric acid which are usually used for coagulating a rubber latex solution, and salts such as sodium chloride can be used. In addition, after the step (ii) and before the step (iii), for the purpose of appropriately reducing the amount of water contained in the filler-containing rubber solidified product, for example, a solidification step such as a centrifugation step or a heating step may be performed. A liquid separation step may be provided.

(3) Step (iii)
In step (iii), a rubber wet masterbatch is manufactured by dehydrating the filler-containing rubber solidified product. In the step (iii), for example, a single-screw extruder is used, and it is possible to perform dehydration while applying a shearing force to the filler-containing rubber solidified product while heating at 100 to 250°C. In the present invention, particularly in the step (iii), the compound described in the above formula (I) is added to the filler-containing rubber solidified product, and the compound is added to the formula (I) in the filler-containing rubber solidified product containing water. The filler-containing rubber solidified product is dehydrated while dispersing the compound (1). The moisture content of the filler-containing rubber solidified product before the step (iii) is not particularly limited, but the solid-liquid separation step and the like are provided as necessary so that Wa/Wb described later is in an appropriate range. It is preferable to adjust the water content so that

As described above, by dispersing the compound represented by the formula (I) in the filler-containing rubber solidified product in the presence of water, the dispersibility thereof is significantly improved. In particular, 1≦Wa/Wb≦8100, where Wa is the water content of the filler-containing rubber solidified product when the compound represented by the formula (I) is added and Wb is the content of the compound represented by the formula (I). It is preferable. When Wa/Wb is less than 1, the dispersibility of the compound represented by the formula (I) in the rubber-containing coagulated product containing a filler may not be sufficiently improved. In order to further improve the dispersibility of the compound represented by the formula (I), Wa/Wb is preferably 1 or more. On the other hand, when Wa/Wb exceeds 8100, the water content to be dehydrated is remarkably increased, so that the productivity of the rubber wet masterbatch tends to be deteriorated. Considering the productivity of the rubber wet masterbatch, Wa/Wb is preferably 7500 or less.

After the step (iii), a drying step may be additionally provided in order to further reduce the moisture content of the rubber wet masterbatch, if necessary. As a method for drying the rubber wet masterbatch, various drying devices such as a single screw extruder, an oven, a vacuum dryer and an air dryer can be used.

(4) Step (iv)
In the step (iv), the rubber wet masterbatch and various compounding agents are dry-mixed to produce a rubber composition, which is molded into a sheet-shaped or tape-shaped cushion rubber. Examples of the molding method include extrusion molding. The thickness of the cushion rubber can be appropriately changed depending on the type of the retreaded tire, and is, for example, 0.1 to 3.0 mm. As a compounding agent that can be used when producing a cushion rubber, for example, a tackifier, a sulfur-based vulcanizing agent, a vulcanization accelerator, an antioxidant, silica, a silane coupling agent, zinc oxide, a methylene acceptor and Examples thereof include methylene donors, stearic acid, vulcanization accelerator aids, vulcanization retarders, organic peroxides, softeners such as waxes and oils, and processing aids and other compounding agents usually used in the rubber industry.

The tackifier is an additive that imparts tackiness to the rubber composition, and is also called a tackifier. From the viewpoint of tackiness as a tread cushion and vulcanization speed, tackifier resins such as alkylphenol resins and petroleum hydrocarbon resins are preferably used, and these may be used alone or in combination.

Examples of the alkylphenol-based resin include an alkylphenol acetylene-based resin which is a polycondensation product of alkylphenol (for example, pt-butylphenol) and acetylene, and an alkylphenol (for example, pt-butylphenol, pt-octylphenol, pt-t-). Examples thereof include alkylphenol formaldehyde resins which are polycondensates of dodecylphenol) and formaldehyde, and alkylphenol acetylene resins are particularly preferable.

Examples of the petroleum hydrocarbon resin include aliphatic petroleum resin, aromatic petroleum resin, and aliphatic/aromatic copolymer petroleum resin. The aliphatic petroleum resin is a resin obtained by cationically polymerizing an unsaturated monomer such as isoprene or cyclopentadiene, which is a petroleum fraction having 4 to 5 carbon atoms (C5 fraction) (C5 petroleum resin). It may also be hydrogenated. The aromatic petroleum resin is a resin obtained by cationically polymerizing a monomer such as vinyltoluene, alkylstyrene, and indene, which is a petroleum fraction having 8 to 10 carbon atoms (C9 fraction) (C9 petroleum). It is also referred to as a resin) or hydrogenated. The aliphatic/aromatic copolymer petroleum resin is a resin obtained by copolymerizing the C5 fraction and the C9 fraction (also referred to as C5/C9 petroleum resin), and is hydrogenated. It may be.

The compounding amount of the tackifier is 0.1 to 10 parts by mass, and more preferably 1 to 8 parts by mass with respect to 100 parts by mass of the total amount of the rubber component contained in the cushion rubber.

Sulfur as a sulfur-based vulcanizing agent may be ordinary sulfur for rubber, and for example, powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used. The content of sulfur in the rubber composition according to the present invention is preferably 0.3 to 6.5 parts by mass with respect to 100 parts by mass of the rubber component. If the sulfur content is less than 0.3 parts by mass, the cross-linking density of the vulcanized rubber will be insufficient and the rubber strength will decrease, and if it exceeds 6.5 parts by mass, both heat resistance and durability will be particularly high. Getting worse. In order to ensure good rubber strength of the vulcanized rubber and further improve heat resistance and durability, the sulfur content should be 1.5 to 5.5 parts by mass with respect to 100 parts by mass of the rubber component. Is more preferable, and it is further preferable that it is 2 to 4.5 parts by mass.

As the vulcanization accelerator, usually used for rubber vulcanization, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization Vulcanization accelerators such as accelerators and dithiocarbamate vulcanization accelerators may be used alone or in admixture as appropriate. The content of the vulcanization accelerator is more preferably 1 to 5 parts by mass, and even more preferably 1.5 to 4 parts by mass with respect to 100 parts by mass of the rubber component.

As the anti-aging agent, usually used for rubber, aromatic amine anti-aging agent, amine-ketone anti-aging agent, monophenol anti-aging agent, bisphenol anti-aging agent, polyphenol anti-aging agent, dithiocarbamic acid Antiaging agents such as salt antiaging agents and thiourea antiaging agents may be used alone or in admixture. The content of the antioxidant is more preferably 1 to 5 parts by mass, and further preferably 2 to 4.5 parts by mass with respect to 100 parts by mass of the rubber component.

Further, in the method for producing a retreaded tire according to the present invention, the step of producing a cushion rubber may add and disperse the compound represented by the formula (I) and water to the mixture of the filler and the rubber. is there. The filler may be the same as that used in the method for producing the rubber wet masterbatch, and the rubber may be a diene rubber known to those skilled in the art, such as natural rubber (NR) or polyisoprene rubber (IR). Polystyrene butadiene rubber (SBR), polybutadiene rubber (BR), chloroprene rubber (CR), nitrile rubber (NBR) and the like can be used.

In the method for manufacturing a retreaded tire according to the present invention, the tread rubber is attached to the base tire via the cushion rubber formed into a sheet shape. In the present invention, both a remolding method and a precure method can be adopted as a method for manufacturing a retreaded tire. In the remolding method, for example, an unvulcanized tread rubber, a molding step of attaching a base tire through a cushion rubber, and a vulcanization step of adding a tread pattern to the tread rubber while vulcanizing in a mold. Have at least. On the other hand, in the pre-cure method, the vulcanized tread rubber with the tread pattern is attached to the base tire via the cushion rubber, and the pre-cure tread attachment molding process for manufacturing the base tire and the pre-cure tread attachment A vulcanization step is performed in which the base tire is mounted on the rim-shaped body, an annular vulcanization envelope is covered over the precure tread-attached base tire, and vulcanized in a vulcanization can.

Regardless of whether the remolding method or the precure method, according to the method for manufacturing a pneumatic tire according to the present invention, the shape stability of the cushion rubber that bonds the tread rubber and the base tire is excellent, and thus the adhesive strength is excellent. It is possible to manufacture retreaded tires.

Hereinafter, embodiments of the present invention will be described to more specifically describe.

(Raw materials used)
a) Carbon black Carbon black "N330";"Showa Black N330T" (manufactured by Cabot Japan)
Carbon black "N550";"Showa Black N550" (manufactured by Cabot Japan)
b) Dispersion solvent Water c) Rubber latex solution Natural rubber latex solution (NR field latex); manufactured by Golden Hope (DRC=31.2%)
d) Compound of formula (I) (2Z)-4-[(4-aminophenyl)amino]-4-oxo-2-butenoic acid sodium salt (Sumitomo Chemical Co., Ltd.)
e) Coagulant Formic acid (85% primary, 10% solution diluted to pH 1.2), "Nacalai Tesque"
f) Tackifier "R7510H" (manufactured by Schenectady)
g) Lunac stearic acid S-20 (Kao soap)
h) Bullcurrent "Bullcurrent E/C" (manufactured by LANXESS)
i) Anti-aging agent "Nocrac 6C" (manufactured by Ouchi Shinko Chemical Co., Ltd.)
j) Sulfur "Mucron OT-20F" (manufactured by Shikoku Chemicals)
k) Vulcanization accelerator (A) 1,3-diphenylguanidine "Nocceller D" (manufactured by Ouchi Shinko Chemical Co., Ltd.)
(B) 2-mercaptobenzothiazole "Nocceller M" (manufactured by Ouchi Shinko Chemical Co., Ltd.)
(C) Zinc dibenzyldithiocarbamate "Nocceller ZTC" (manufactured by Ouchi Shinko Chemical Co., Ltd.)
l) Natural rubber (NR) "RSS#3"
m) ZnO "ZINC OXIDE KS-2" (SBCHEMICAL)
o) Oil "NC-140" (made by Japan Energy)

Example 1
Carbon black was added to the diluted aqueous solution of natural rubber diluted to a concentration of 0.52% by mass so that the compounding amount shown in Table 1 was obtained (concentration of carbon black with respect to water was 5% by mass), and this was manufactured by PRIMIX. By dispersing carbon black using Robomix (conditions of the Robomix: 9000 rpm, 30 minutes), a carbon black-containing slurry solution having the natural rubber latex particles shown in Table 1 attached was prepared (step (i. )-(A)). Next, the natural rubber latex solution (25% by mass) was added to the carbon black-containing slurry solution to which the natural rubber latex particles produced in step (i-(a)) were adhered so that the compounding amount was as shown in Table 1. Then, the mixture was mixed using a SANYO household mixer SM-L56 type (mixer condition 11300 rpm, 30 minutes) to produce a carbon black-containing rubber latex solution to which natural rubber latex particles were attached (step (i )).

A formic acid as a coagulant was added to the carbon black-containing natural rubber latex solution to which the natural rubber latex particles produced in step (i) were attached until the pH of the entire solution reached 4, thereby producing a carbon black-containing natural rubber coagulated product. (Step (ii)). The obtained carbon black-containing natural rubber coagulated product is subjected to a solid-liquid separation step, if necessary, to obtain the water content shown in Table 1, and the carbon black-containing natural rubber coagulated product and the formula ( The compound described in I) is charged into a screw press type V-01 manufactured by Suehiro EPM Co., and the compound described in Formula (I) is dispersed in the carbon black-containing natural rubber coagulated product while the carbon black-containing natural rubber coagulated product is dispersed. Was dehydrated to produce a rubber wet masterbatch (step (iii)). Table 1 shows the values of Wa/Wb in the step (iii).

A rubber composition was produced by dry mixing the rubber wet masterbatch obtained in Example 1 and the various compounding agents shown in Table 1 using a Banbury mixer (step (iv)). The compounding ratios in Table 1 are shown in parts by mass (phr) when the total amount of rubber components is 100 parts by mass.

Comparative Examples 1-2
Instead of producing a rubber wet masterbatch, the rubber component, carbon black and various compounding agents shown in Table 1 are dry-mixed in a completely dry state by using a Banbury mixer to give a rubber composition and an additive. A vulcanized rubber was produced.

Comparative Example 3
A rubber composition and a vulcanized rubber thereof were produced in the same manner as in Example 1 except that in the step (iii), the compound containing the formula (I) was not added to the filler-containing rubber solidified product.

Comparative Example 4
In the step (iv), a rubber composition and a vulcanized rubber thereof were produced by the same method as in Example 1 except that the compound described in the formula (I) was added to the filler-containing rubber solidified product in a dry state. ..

Comparative Example 5
In the step (iii), the rubber composition and its vulcanized rubber were prepared in the same manner as in Example 1 except that the compound represented by the formula (I) was added at the stage where the filler-containing rubber solidified product was completely dried. Was manufactured.

The obtained rubber composition was taken out of the sheet with a roll of 1.0 kg and 10 inches, the length after 24 hours was measured at 23° C., and the value of Comparative Example 1 was set to 100, and the index was evaluated. The larger the value, the better the shape stability. The results are shown in Table 1.

Claims (2)

A method for manufacturing a retreaded tire in which a tread rubber is attached to a base tire through a cushion rubber for adhesion,
In the step of manufacturing the cushion rubber, a step (i) of manufacturing a filler-containing rubber latex solution by mixing a filler, a dispersion solvent, and a rubber latex solution; coagulating and filling the filler-containing rubber latex solution. (Ii) for producing a material-containing rubber solidified product, a step (iii) for producing a rubber wet masterbatch by dehydrating the filler-containing rubber solidified product, and a rubber composition containing the rubber wet masterbatch Has a step (iv) of molding
In the step (iii), a compound represented by the following formula (I) is added to the filler-containing rubber solidified product:

(In the formula (I), R ¹ and R ² represent a hydrogen atom and an alkyl group, an alkenyl group or an alkynyl group having 1 to 20 carbon atoms, and R ¹ and R ² may be the same or different. M ⁺ represents sodium ion, potassium ion or lithium ion), and the compound of formula (I) is dispersed in the filler-containing rubber coagulated product containing water, and the filling is performed. A method for producing a retreaded tire, which comprises a step of dehydrating a material-containing rubber solidified product. In the step (iii), when the amount of water in the filler-containing rubber coagulum at the time of adding the compound of the formula (I) is Wa and the content of the compound of the formula (I) is Wb, The method for manufacturing a retreaded tire according to claim 1, wherein 1≦Wa/Wb≦8100.