Method for producing aggregate of natural rubber and apparatus for producing aggregate of natural rubber

Abstract

To provide a method for producing an aggregate of natural rubber by which the remaining of unreacted natural rubber latex and acid can be suppressed.SOLUTION: A method for producing a natural rubber aggregate, the method comprising: dropping a first mixture of natural rubber latex and an acid toward a mixture flow path through which a serum component of the natural rubber flows to obtain a second mixture of the first mixture and the serum component; and pouring the second mixture that has flowed through the mixture flow path into a receiving container to obtain an aggregate in which the natural rubber latex and the acid are aggregated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a natural rubber agglomerate and an apparatus for producing a natural rubber agglomerate. [Background technology]

[0002] Natural rubber latex is generally produced in tropical countries such as Thailand, Malaysia, and Indonesia. Due to its excellent physical properties, natural rubber latex is widely used in large quantities in the rubber and tire industries. Natural rubber latex is produced through the following steps: tapping, coagulation, washing (with water), dehydration, drying, and packing. It is classified by its type and grade, and is broadly divided into Ribbed Smoked Sheet (RSS) and Technically Graded Rubber (TSR), based on the International Quality Packaging Standard for Various Grades of Natural Rubber Latex (commonly known as the Green Book).

[0003] In the rubber industry, when natural rubber obtained by the above-mentioned methods is used to produce rubber products for various uses, it is usually subjected to a mastication process before use, in order to improve mixing efficiency by reducing the molecular weight and gel content.

[0004] For example, Patent Document 1 discloses a natural rubber mixture obtained by treating natural rubber latex with at least one of a surfactant and an enzyme, and then adding a hydrazide compound and / or a serum component of natural rubber. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-313366 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, attempts have been made to obtain coagulated natural rubber by adding an acid to natural rubber latex. However, when an acid is added to natural rubber latex, coagulation proceeds rapidly, resulting in the formation of non-uniform coagulates, and large amounts of unreacted natural rubber latex and acid remain. Therefore, there is a need to prevent the remaining unreacted natural rubber latex and acid when adding an acid to natural rubber latex to obtain a natural rubber coagulate.

[0007] Therefore, an object of the present disclosure is to provide a method and an apparatus for producing natural rubber agglomerates that can suppress the remaining unreacted natural rubber latex and acid. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. The first aspect is a step of dropping a first mixture of natural rubber latex and acid toward a mixture flow path through which a serum component of natural rubber flows, thereby obtaining a second mixture of the first mixture and the serum component; an agglomeration step of pouring the second mixture that has flowed through the mixture flow path into a receiving container to obtain an agglomerate in which the natural rubber latex and the acid are agglomerated; The present invention relates to a method for producing an agglomerate of natural rubber having the following structure: The second aspect is the first mixture is obtained by bringing the natural rubber latex flowing through a first flow path into contact with the acid flowing through a second flow path at a contact portion between the first flow path and the second flow path, The first mixture is dropped toward the mixture flow path arranged below the contact portion in a vertical direction. A method for producing an agglomerate of natural rubber according to the first aspect. The third aspect is As the natural rubber latex, a treated natural rubber latex which has been treated with at least one of a surfactant and an enzyme is used. A method for producing the natural rubber agglomerate according to the first aspect or the second aspect.

[0009] The fourth aspect is a mixture flow path through which the serum component of natural rubber flows; a drop section through which the first mixture of natural rubber latex and acid falls vertically downward toward the mixture flow path; a receiving container into which a second mixture obtained by mixing the first mixture and the serum component in the mixture flow path flows, a coagulation product can be obtained by coagulating the natural rubber latex and the acid. This is a natural rubber agglomerate manufacturing device. The fifth aspect is a first flow path through which the natural rubber latex flows; a second flow path through which the acid flows; a contact section where the natural rubber latex flowing through the first flow path comes into contact with the acid flowing through the second flow path to obtain the first mixture of the natural rubber latex and the acid; and In the falling section, the first mixture falls vertically downward from the contact section. 10 is an apparatus for producing a natural rubber agglomerate according to a fourth embodiment. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a method for producing a natural rubber agglomerate and an apparatus for producing a natural rubber agglomerate that can suppress the remaining unreacted natural rubber latex and acid. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of an apparatus for producing a natural rubber aggregate according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0030] The following describes exemplary embodiments of the present disclosure, which are intended to illustrate the embodiments and are not intended to limit the scope of the invention. In this specification, a numerical range expressed using "to" means a range that includes these numerical values ​​as the lower limit and upper limit. In the present specification, in which numerical ranges are described in stages, the upper limit of one numerical range may be replaced by the upper limit of another numerical range, and the lower limit of one numerical range may be replaced by the lower limit of another numerical range. Furthermore, "%" in the content means "% by mass" unless otherwise specified.

[0013] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified. The term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0014] <Method and apparatus for producing natural rubber agglomerates> A method for producing a natural rubber agglomerate according to an embodiment of the present disclosure includes a step of dropping a first mixture of natural rubber latex and an acid into a mixture flow path through which a serum component of natural rubber flows, thereby obtaining a second mixture of the first mixture and the serum component, and an agglomeration step of pouring the second mixture that has flowed through the mixture flow path into a receiving container, thereby obtaining an agglomerate of the natural rubber latex and the acid.

[0015] A natural rubber agglomerate manufacturing apparatus according to an embodiment of the present disclosure includes a mixture flow path through which a serum component of natural rubber flows, a drop section through which a first mixture of natural rubber latex and an acid falls vertically downward toward the mixture flow path, and a receiving container into which a second mixture obtained by mixing the first mixture with the serum component in the mixture flow path flows, and is capable of producing an agglomerate formed by agglomerating the natural rubber latex and the acid.

[0016] Hereinafter, a method for producing a natural rubber agglomerate and an apparatus for producing a natural rubber agglomerate according to an embodiment of the present disclosure will be specifically described with reference to the drawings.

[0017] FIG. 1 is a schematic diagram illustrating an example of an apparatus for producing a natural rubber aggregate according to an embodiment of the present disclosure.

[0018] 1 includes a first gutter 41 forming a first flow path through which natural rubber latex 2 flows, a second gutter 42 forming a second flow path through which acid 4 flows, a contact section 40 where the natural rubber latex 2 flowing through the first flow path comes into contact with the acid 4 flowing through the second flow path, a drop section 50 through which the first mixture falls from the contact section 40, a slider 43 disposed vertically below the contact section 40 and forming a mixture flow path through which the natural rubber serum component 6 flows and through which the first mixture falls through the drop section 50, and a receiving container 74 into which a second mixture obtained by mixing the first mixture and the serum component 6 on the slider 43 flows. Formic acid, for example, is used as the acid 4.

[0019] The manufacturing apparatus 100 will be described in more detail below.

[0020] A first tank 21 is provided upstream of the first gutter 41 as a first storage tank for storing the natural rubber latex 2 and having a plurality of first holes 210 in the floor surface.

[0021] A first storage container 11 that stores natural rubber latex 2 is provided upstream of the first tank 21. A pH meter 61 that monitors the pH of the natural rubber latex 2 is disposed in the first storage container 11. A pH adjustment nozzle 14 for adding an alkaline pH adjusting solution (e.g., ammonia) is disposed in the upper part of the first storage container 11. The pH adjustment nozzle 14 has an adjustment valve 14a. An agitator 18 for stirring the natural rubber latex 2 is disposed in the first storage container 11. The pH adjusting solution is added from the pH adjustment nozzle 14 to the natural rubber latex 2 in the first storage container 11 in accordance with the pH monitored by the pH meter 61, and the natural rubber latex 2 is stirred by the agitator 18, thereby controlling the pH of the natural rubber latex 2 within a certain range.

[0022] The natural rubber latex 2 is poured into the first tank 21 from the first storage container 11 through a first nozzle 31. The first nozzle 31 has an adjusting valve 31a, and the amount of natural rubber latex 2 poured into the first tank 21 can be controlled by the adjusting valve 31a.

[0023] The first tank 21 has a plurality of first holes 210 on its floor surface. The natural rubber latex 2 stored in the first tank 21 falls as droplets 2a from the first holes 210 toward the first gutter 41 that forms the first flow path. The state of the natural rubber latex 2 falling from the first tank 21 toward the first flow path formed by the first gutter 41 is not limited to droplets, and may be, for example, thin streaks (i.e., a state in which a small amount of liquid falls in a continuous stream). The amount of natural rubber latex 2 falling from the first holes 210 is controlled by the diameter of the first holes 210 and the distance between the first holes 210. By dropping the natural rubber latex 2 from the first tank 21 through the first hole 210, the amount of natural rubber latex 2 supplied to the first gutter 41 forming the first flow path can be adjusted.

[0024] The first gutter 41 has an inclined surface 41a that slopes toward the contact portion 40. The inclined surface 41a forms a first flow path. Droplets 2a of the natural rubber latex 2 that fall from the first tank 21 through the first hole 210 reach the inclined surface 41a of the first gutter 41. Then, the natural rubber latex 2 that has reached the first gutter 41 flows on the inclined surface 41a in the inclined direction (i.e., the direction of arrow A) and reaches the contact portion 40.

[0025] Here, the method of supplying natural rubber latex 2 to the inclined surface 41a of the first gutter 41 is not limited to the method of dropping droplets 2a of natural rubber latex 2 from the first tank 21 through the first hole 210 as shown in FIG. 1 . For example, natural rubber latex 2 may be supplied directly from the first storage container 11 to the inclined surface 41a of the first gutter 41 through a nozzle. When supplying natural rubber latex 2 from the first storage container 11 to the inclined surface 41a using a nozzle, it is preferable to arrange multiple nozzles in a first orthogonal direction (i.e., the direction of arrow E) that is perpendicular to the inclination direction of the inclined surface 41a (i.e., the direction of arrow A). By arranging multiple nozzles in the direction of arrow E, the amount of natural rubber latex 2 supplied to the first gutter 41, which forms the first flow path, can be adjusted.

[0026] A second tank 22 serving as a second storage tank for storing the acid 4 and having a plurality of second holes 220 on the floor surface is provided upstream of the second gutter 42.

[0027] A second storage vessel 12 containing acid 4 is provided upstream of the second tank 22. The acid 4 is poured into the second tank 22 from the second storage vessel 12 through a second nozzle 32. The second nozzle 32 has an adjustment valve 32a, which can control the amount of acid 4 injected into the second tank 22.

[0028] The second tank 22 has a plurality of second holes 220 in its floor surface. The acid 4 stored in the second tank 22 falls as droplets 4a from the second holes 220 toward the second gutter 42 that forms the second flow path. The state of the acid 4 falling from the second tank 22 toward the second flow path formed by the second gutter 42 is not limited to droplets, and may be, for example, thin streaks (i.e., a state in which a small amount of liquid falls in a continuous stream). The amount of acid 4 falling from the second holes 220 is controlled by the diameter of the second holes 220 and the distance between the second holes 220. By dropping the acid 4 from the second tank 22 through the second hole 220, the amount of acid 4 supplied to the second gutter 42 forming the second flow path can be adjusted.

[0029] The second gutter 42 has an inclined surface 42a that slopes toward the contact section 40. The inclined surface 42a forms a second flow path. Droplets 4a of acid 4 that fall from the second tank 22 through the second hole 220 reach the inclined surface 42a of the second gutter 42. The acid 4 that reaches the second gutter 42 then flows on the inclined surface 42a in the inclined direction (i.e., the direction of arrow B) to reach the contact section 40.

[0030] Here, the method of supplying the acid 4 to the inclined surface 42a of the second gutter 42 is not limited to the method of dropping droplets 4a of the acid 4 from the second tank 22 through the second hole 220 as shown in FIG. 1 . For example, the acid 4 may be supplied directly from the second storage container 12 to the inclined surface 42a of the second gutter 42 through a nozzle. When supplying the acid 4 from the second storage container 12 to the inclined surface 42a using a nozzle, it is preferable to arrange multiple nozzles in a second orthogonal direction (i.e., the direction of arrow E) that is perpendicular to the inclination direction of the inclined surface 42a (i.e., the direction of arrow B). By arranging multiple nozzles in the direction of arrow E, the amount of acid 4 supplied to the second gutter 42, which forms the second flow path, can be adjusted.

[0031] The natural rubber latex 2 flowing through the first flow path on the inclined surface 41a of the first gutter 41 and the acid 4 flowing through the second flow path on the inclined surface 42a of the second gutter 42 come into contact with each other at the contact section 40 to form a first mixture (first mixing process).

[0032] The first mixture obtained by contacting the natural rubber latex 2 with the acid 4 in the contact section 40 falls through the falling section 50 vertically downward from the contact section 40 (ie, in the direction of arrow C).

[0033] The slider 43 has an inclined surface 43a that slopes toward the receiving container 74. The inclined surface 43a forms a mixture flow path. A natural rubber serum component 6 is supplied to the inclined surface 43a of the slider 43 from the third nozzle 33. The third nozzle 33 has an adjustment valve 33a, which can control the amount of serum component 6 supplied to the inclined surface 43a. The serum component 6 supplied to the inclined surface 43a of the slider 43 flows on the inclined surface 43a in the inclined direction (i.e., in the direction of arrow D).

[0034] The first mixture, which has fallen from contact section 40 through falling section 50 in the direction of arrow C, reaches inclined surface 43a of slider 43. The first mixture that has fallen onto inclined surface 43a comes into contact with and is mixed with serum component 6 that has flowed on inclined surface 43a in the direction of arrow D, thereby obtaining a second mixture of the first mixture and serum component 6 (second mixing step).

[0035] The second mixture then flows on the inclined surface 43a in the inclined direction (i.e., the direction of arrow E) and into the receiving container 74. A pH meter 62 is disposed on the inclined surface 43a to monitor the pH of the second mixture flowing in the direction of arrow E.

[0036] In the first mixture obtained by contacting the natural rubber latex 2 with the acid 4 in the contact section 40, and in the second mixture obtained by contacting the first mixture with the serum component 6 on the inclined surface 43a of the slider 43, aggregation of the natural rubber latex 2 and the acid 4 progresses. That is, while the mixture falls down the drop section 50 in the direction of arrow C from the contact section 40, flows along the inclined surface 43a of the slider 43 toward the receiving container 74 and flows into the receiving container 74, and after flowing into the receiving container 74, aggregates 72 of the natural rubber latex 2 and the acid 4 are formed in the first mixture and the second mixture (aggregation step), and the aggregates 72 are stored in the pool 70 of the receiving container 74. The second mixture flowing into the pool 70 contains at least the natural rubber latex 2, the acid 4, and the serum component 6. A pH meter 63 for monitoring the pH is disposed in the pool 70 in the receiving container 74.

[0037] According to the method and apparatus for producing a natural rubber agglomerate according to the embodiments of the present disclosure, when an acid is added to natural rubber latex to obtain a natural rubber agglomerate, it is possible to suppress the remaining unreacted natural rubber latex and acid. The reason why this effect is achieved is described below.

[0038] A conventional method involves adding acid to natural rubber latex to obtain coagulated natural rubber. However, when acid is added to natural rubber latex, coagulation proceeds rapidly, resulting in non-uniform coagulation, meaning that large amounts of unreacted natural rubber latex and acid remain in the first mixture. This is thought to be because coagulation proceeds rapidly at the points where the natural rubber latex and acid come into contact in the first mixture, and the unreacted acid is incorporated into the coagulated areas, leaving unreacted acid and natural rubber latex. Therefore, there is a need to prevent the remaining unreacted natural rubber latex and acid when adding acid to natural rubber latex to obtain natural rubber coagulation.

[0039] In contrast, in the method and apparatus for producing a natural rubber agglomerate according to the embodiments of the present disclosure, a serum component is further mixed into a first mixture of natural rubber latex and acid. The addition of the serum component stabilizes the aggregation of the natural rubber latex and acid, and suppresses the remaining unreacted natural rubber latex and acid. Furthermore, by allowing the first mixture of natural rubber latex and acid to fall toward the mixture flow path through which the serum component of natural rubber flows, the natural rubber latex, acid, and serum component are mixed more uniformly. Mixing each component more uniformly promotes the reaction between the natural rubber latex and the acid. From this perspective, remaining unreacted natural rubber latex and acid are suppressed.

[0040] As described above, the method and apparatus for producing a natural rubber agglomerate according to the embodiments of the present disclosure can reduce the amount of unreacted natural rubber latex and acid remaining when adding acid to natural rubber latex to obtain a natural rubber agglomerate, thereby reducing variation in the quality of the obtained natural rubber agglomerate and increasing the yield.

[0041] Serum components of natural rubber The natural rubber serum component (also referred to as "serum") used in embodiments of the present disclosure contains useful components that exhibit heat aging prevention effects on the rubber component, such as inositol, carbohydrates, proteins such as α-globulin, sugars, an ammonia source, minerals, glutathione, enzymes, and nucleic acids. The addition of the serum component stabilizes the aggregation of natural rubber latex and acid, suppressing the remaining unreacted natural rubber latex and acid. Furthermore, the use of the serum component enables effective utilization of natural rubber resources.

[0042] As the serum component of natural rubber, for example, serum obtained from natural rubber latex by centrifugation, or a coagulated product thereof, can be used.

[0043] The amount of the natural rubber serum component added is preferably 2 parts by mass or more, and more preferably 5 to 30 parts by mass, per 100 parts by mass of the dry content of the natural rubber latex, calculated as solids. By adding the serum component in an amount of 2 parts by mass or more, the aggregation of the natural rubber latex and the acid is further stabilized, and the remaining unreacted natural rubber latex and acid are further suppressed.

[0044] Natural rubber latex The natural rubber latex used in the embodiments of the present disclosure is not particularly limited, and general natural rubber latex that forms aggregates upon reaction with acid can be used. Among them, from the viewpoints of reducing the odor of the latex and improving processability, it is preferable to use natural rubber latex that has been treated to reduce the amount of non-rubber components such as proteins in the natural rubber (specifically, at least one of proteins and lipids (preferably both proteins and lipids) has been decomposed). Methods for obtaining natural rubber latex in which at least one of proteins and lipids has been decomposed include, for example, a method of treating natural rubber latex with at least one of a surfactant and an enzyme, a method of saponifying natural rubber latex (for example, a method of adding an aqueous sodium hydroxide solution to natural rubber latex to decompose at least one of proteins and lipids), etc. Among these, natural rubber latex treated with at least one of a surfactant and an enzyme (hereinafter also referred to as "treated natural rubber latex") is preferred.

[0045] However, natural rubber latex in which at least one of proteins and lipids has been decomposed (particularly treated natural rubber latex) tends to coagulate more rapidly when acid is added, and as a result, unreacted natural rubber latex and acid are likely to remain in the first mixture. However, according to the method for producing a natural rubber agglomerate and the apparatus for producing a natural rubber agglomerate according to the embodiments of the present disclosure, as described above, it is possible to suppress the remaining unreacted natural rubber latex and acid.

[0046] Examples of natural rubber latex include tapped natural rubber latex itself, natural rubber latex stabilized by adding an acid such as sulfuric acid or an alkali such as ammonia, and concentrated natural rubber latex obtained by centrifuging with a centrifuge, and the rubber concentration (Dry rubber content; DRC) of these natural rubber latexes may be 5% by mass or more in terms of solid content.

[0047] Surfactants that can be used to obtain natural rubber latex that has been treated to reduce the amount of non-rubber components in the natural rubber (specifically, by decomposing at least one of proteins and lipids) are not particularly limited as long as they reduce the amount of non-rubber components in the natural rubber, and examples include anionic surfactants, nonionic surfactants, etc. Examples of anionic surfactants include carboxylates such as fatty acid soaps, N-acylamino acids and their salts, polyoxyethylene or POE alkyl ether carboxylates, and acylated peptides; sulfonates such as alkyl sulfonates, alkylbenzene and alkylnaphthalene sulfonates, naphthalene sulfonate-formalin polycondensates, sulfosuccinates, α-olefin sulfonates, and N-acylsulfonates; sulfate ester salts such as sulfated oils, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or POE alkyl allyl ether sulfates, and alkylamide sulfates; and phosphate ester salts such as alkyl phosphates, polyoxyethylene or POE alkyl ether phosphates, and polyoxyethylene or POE alkyl allyl ether phosphates. Examples of nonionic surfactants include ether-type surfactants such as polyoxyethylene alkyl and alkylphenyl ethers, alkylallyl formaldehyde condensed polyoxyethylene ethers, polyoxyethylene polyoxypropylene block copolymers, and polyoxyethylene polyoxypropyl alkyl ethers; ether-ester-type surfactants such as polyoxyethylene ethers of glycerin esters, polyoxyethylene ethers of sorbitan esters, and polyoxyethylene ethers of sorbitol esters; ester-type surfactants such as polyoxyethylene glycol fatty acid esters, glycerin esters, polyglycerin esters, sorbitan esters, propylene glycol esters, and sucrose esters; and nitrogen-containing surfactants such as fatty acid alkanolamides, polyoxyethylene fatty acid amides, and polyoxyethylene alkylamines. Enzymes that can be used to obtain natural rubber latex that has been treated to reduce the amount of non-rubber components in the natural rubber (specifically, by decomposing at least one of proteins and lipids) are not particularly limited as long as they reduce the amount of non-rubber components in the natural rubber, and examples include protease enzymes such as papain and Alcalase, and cellulase enzymes such as Cellzyme. These can be used alone or in combination of two or more. Preferably, protease enzymes and cellulase enzymes are used in order to reduce the amount of non-rubber components in the natural rubber.

[0048] These surfactants and enzymes can be used alone or in combination. From the viewpoint of the stability of natural rubber latex, it is preferable to use long-chain fatty acid salts (soaps) such as sodium laurate, alkyl sulfates (AS) such as sodium dodecyl sulfate, alkyl polyoxyethylene sulfates (AES), α-olefin sulfonates (AOS), alkyl benzene sulfonates (ABS, LAS), and potassium dehydrated castor oil. Commercially available detergents containing the surfactants and enzymes mentioned above, such as Kao Corporation's "Attack," "New Attack," and "Attack New Compound," which contain cellulase enzymes, Miyoshi Oil & Fats' "High Density Compact Soap," which contains surfactants but no enzymes, Shabondama Snoll, which is manufactured by Shabondama Soap Co., Ltd., and Okamoto Corporation's "Gentle Soap," can also be used.

[0049] As a means for treating natural rubber latex by adding at least one of a surfactant and an enzyme, for example, at least one of a surfactant and an enzyme may be added before coagulation of the collected natural rubber latex, or may be applied by immersion or spraying before drying, or may be added using a dry pre-breaker after drying, and the natural rubber latex may be kneaded using a mixer, kneader, or the like, to obtain the desired natural rubber mixture.

[0050] The amount of at least one of the surfactant and the enzyme added is desirably 0.02 part by mass or more, preferably 0.05 to 4 parts by mass, per 100 parts by mass of the dry content of the natural rubber latex. By adding at least one of these surfactants and enzymes in an amount of 0.02 part by mass or more, the amount of non-rubber components in the natural rubber can be reduced without causing adverse effects such as a decrease in the physical properties of the rubber.

[0051] ·acid The acid added to the natural rubber latex to obtain the coagulate may be, for example, formic acid, acetic acid, propionic acid, sulfuric acid, etc. Formic acid is particularly preferred.

[0052] From the viewpoint of suppressing the remaining unreacted natural rubber latex and acid, it is preferable to adjust the amount of acid added to the mixture so that the pH of the mixture immediately after the natural rubber latex and acid come into contact with each other at the contact portion (the pH measured by pH meter 62 arranged on inclined surface 43 a in FIG. 1 ) falls within the range described below.

[0053] pH of the first mixture The pH of the first mixture immediately after contact between the natural rubber latex and the acid at the contact portion (as measured by pH meter 62 arranged on inclined surface 43a in FIG. 1) is preferably 4.2 or more and 5.2 or less. By controlling the pH of the first mixture within the above range, coagulation of the natural rubber latex and the acid proceeds smoothly, and the amount of remaining unreacted natural rubber latex and acid is further reduced. It is even more preferable that the pH of the first mixture immediately after contact between the natural rubber latex and the acid is 4.4 or more and 5.0 or less.

[0054] The pH of the first mixture immediately after the natural rubber latex and the acid have come into contact can be adjusted by the pH of the natural rubber latex (for example, the pH of natural rubber latex 2 contained in first storage container 11 in FIG. 1 ), the pH of the acid (for example, the pH of acid 4 contained in second storage container 12 in FIG. 1 ), and the amounts of natural rubber latex and acid supplied to the contact section (for example, the amounts of natural rubber latex 2 and acid 4 supplied to contact section 40 in FIG. 1 ). The pH of the natural rubber latex (for example, the pH of natural rubber latex 2 stored in first storage container 11 in FIG. 1 ) is preferably controlled to, for example, pH 10±0.5. The pH of the acid (for example, the pH of acid 4 stored in second storage container 12 in FIG. 1 ) is preferably 1.0 or higher, and more preferably 2.0 or higher, from the viewpoint of ensuring appropriate dispersion of the acid and mixing a sufficient amount of liquid, in order to adjust the pH of the first mixture during aggregation (i.e., the pH of the first mixture immediately after contact between the natural rubber latex and the acid) to 4.4 or higher and 5.0 or lower.

[0055] pH of the second mixture The pH of the second mixture (i.e., pool 70) that has flowed into receiving vessel 74 (as measured by pH meter 63 disposed in receiving vessel 74 in FIG. 1) is preferably 4.2 or higher and 5.2 or lower. By controlling the pH of the second mixture within the above range, the coagulation of the natural rubber latex and the acid proceeds smoothly, and the amount of unreacted natural rubber latex and the acid remaining is further reduced. The pH of the second mixture that has flowed into receiving vessel 74 is more preferably 4.4 or higher and 5.0 or lower.

[0056] The pH of the second mixture that has flowed into receiving container 74 can be adjusted by the pH of the natural rubber latex, the pH of the acid, the amounts of natural rubber latex and acid supplied to the contact portion, the pH of the serum component (for example, in FIG. 1, the pH of serum component 6 supplied to inclined surface 43a of slider 43), and the amount of serum component 6 supplied to the first mixture (for example, in FIG. 1, the amount of serum component 6 that flows down inclined surface 43a of slider 43 and is mixed with the first mixture). The pH of the serum component 6 (for example, the pH of the serum component 6 supplied to the inclined surface 43a of the slider 43 in FIG. 1) is preferably controlled to, for example, pH 4.7±0.5.

[0057] The natural rubber agglomerate obtained by the method for producing a natural rubber agglomerate according to an embodiment of the present disclosure and the natural rubber agglomerate obtained using the apparatus for producing a natural rubber agglomerate according to an embodiment of the present disclosure (hereinafter, both will be collectively referred to as the "natural rubber agglomerate according to an embodiment of the present disclosure") may be used as a natural rubber alone, or may be used by mixing with various other synthetic rubbers. As the other synthetic rubber, a diene-based synthetic rubber is preferably used from the viewpoint of polymer compatibility (uniform dispersion). Examples of diene-based synthetic rubbers that can be used include at least one selected from isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, and styrene-isoprene copolymer rubber. In particular, from the viewpoint of heat resistance, at least one selected from isoprene rubber, styrene-butadiene copolymer rubber, and butadiene rubber is desirable. When mixed with other synthetic rubbers, the content of the natural rubber agglomerate according to an embodiment of the present disclosure is preferably 2 to 100% by mass, more preferably 5 to 80% by mass, and even more preferably 10 to 70% by mass, based on the total amount of all rubber components.

[0058] The natural rubber agglomerate according to the embodiment of the present disclosure may contain optional components such as fillers, reinforcing agents, softeners, vulcanizing agents, vulcanization accelerators, vulcanization accelerator aids, antioxidants, and resins, as needed. The natural rubber agglomerate according to the embodiment of the present disclosure can be suitably used for various rubber products, including rubber for tires, for example. [Explanation of symbols]

[0059] 2. Natural rubber latex 4. Acid 2a, 4a droplet 6 Serum components 11 First containment vessel 12 Second Containment Vessel 14 pH adjustment nozzle 18 Mixer 21 First Tank 22 Second Tank 31 No. 1 nozzle 32 Second nozzle 33 Third nozzle 31a, 32a, 33a Regulating valve 40 Contact area 41 First Gutter 42 Second Gutter 43 Slider 41a, 42a, 43a Slope 50 Drop Section 61, 62, 63 pH meters 70 Pool 72 Aggregates 74 Receiving container 100 Manufacturing equipment 210 Hole 1 220 2nd hole

Claims

1. a step of dropping a first mixture of natural rubber latex and acid toward a mixture flow path through which a serum component of natural rubber flows, thereby obtaining a second mixture of the first mixture and the serum component; an agglomeration step of pouring the second mixture that has flowed through the mixture flow path into a receiving container to obtain an agglomerate in which the natural rubber latex and the acid are agglomerated; A method for producing a natural rubber agglomerate comprising:

2. the first mixture is obtained by bringing the natural rubber latex flowing through a first flow path into contact with the acid flowing through a second flow path at a contact portion between the first flow path and the second flow path, The first mixture is allowed to fall toward the mixture flow path that is disposed below the contact portion in a vertical direction. A method for producing the natural rubber agglomerate according to claim 1.

3. 2. The method for producing a natural rubber agglomerate according to claim 1, wherein the natural rubber latex is treated with at least one of a surfactant and an enzyme.

4. a mixture flow path through which the serum component of natural rubber flows; a drop section through which the first mixture of natural rubber latex and acid falls vertically downward toward the mixture flow path; a receiving container into which a second mixture obtained by mixing the first mixture and the serum component in the mixture flow path flows, The apparatus for producing a natural rubber agglomerate is capable of obtaining an agglomerate in which the natural rubber latex and the acid are agglomerated.

5. a first flow path through which the natural rubber latex flows; a second flow path through which the acid flows; a contact section where the natural rubber latex flowing through the first flow path and the acid flowing through the second flow path come into contact with each other to obtain the first mixture of the natural rubber latex and the acid; and In the falling section, the first mixture falls vertically downward from the contact section. The apparatus for producing the natural rubber agglomerate according to claim 4.

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