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

Abstract

To provide an uncoagulated treated natural rubber latex and a method for producing a natural rubber coagulum capable of suppressing the remaining of an acid.SOLUTION: A method for producing a natural rubber aggregate, the method comprising a mixing step of bringing a treated natural rubber latex flowing through a first flow path into contact with an acid flowing through a second flow path at a contact portion between the first flow path and the second flow path to obtain a mixture of the treated natural rubber latex and the acid, and an aggregation step of allowing the mixture to fall toward a third flow path disposed vertically below the contact portion and allowing the mixture flowing through the third flow path to flow into a receiving container to obtain an aggregate in which the treated 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 is widely used in large quantities in the rubber and tire industries. Natural rubber is produced through the following steps: latex collection by tapping, coagulation, washing (with water), dehydration, drying, and packing. It is classified by species and grade, and is broadly divided into Ribbed Smoked Sheet (RSS) and Technically Graded Rubber (TSR), based on the grading criteria of the International Quality Packaging Standard for Various Grades of Natural Rubber (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] Incidentally, methods of obtaining coagulated natural rubber by adding acid to natural rubber latex have been attempted. Meanwhile, natural rubber has been developed in which proteins and lipids have been partially decomposed by pretreatment such as enzyme treatment in order to modify natural rubber. However, when acid is added to pretreated natural rubber latex, coagulation proceeds rapidly, resulting in the formation of non-uniform coagulated materials, and uncoagulated natural rubber latex and acid remain, resulting in a problem of reduced yield of coagulated natural rubber. Therefore, there is a need to prevent the uncoagulated natural rubber latex and acid from remaining when adding acid to natural rubber latex to obtain natural rubber coagulates.

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

[0008] Means for solving the above problems include the following aspects. The first aspect of the present invention is a method for producing a natural rubber latex by decomposing at least one of proteins and lipids in the natural rubber latex through a pretreatment process, a mixing step of bringing the treated natural rubber latex flowing through a first flow path into contact with the acid flowing through a second flow path at a contact point between the first flow path and the second flow path to obtain a mixture of the treated natural rubber latex and the acid; an agglomeration step of dropping the mixture toward a third flow path that is disposed vertically below the contact portion and pouring the mixture that has flowed through the third flow path into a receiving container to obtain an agglomerate of the treated natural rubber latex and the acid; The present invention relates to a method for producing an agglomerate of natural rubber having the following structure: In a second aspect, a first dropping step is performed to drop the treated natural rubber latex from a first storage tank that stores the treated natural rubber latex and has a first hole in a floor surface thereof through the first hole toward the first flow path; a second dropping step of dropping the acid from a second storage tank that stores the acid and has a second hole in its floor surface toward the second flow path through the second hole; The method for producing a natural rubber agglomerate according to the first aspect, In a third aspect, the first storage tank has a plurality of the first holes on the floor surface, the first holes are arranged in a first orthogonal direction that is orthogonal to the direction in which the treated natural rubber latex flows through the first flow path, the average hole diameter of the first holes is 1 mm or more and 10 mm or less, and the average interval between the first holes in the first orthogonal direction is 10 mm or more and 50 mm or less, the second reservoir tank has a plurality of the second holes on the floor surface, the second holes are arranged in a second orthogonal direction perpendicular to the direction in which the acid flows through the second flow path, the second holes have an average hole diameter of 1 mm or more and 10 mm or less, and the average interval between the second holes in the second orthogonal direction is 10 mm or more and 50 mm or less; A method for producing an agglomerate of natural rubber according to the second aspect. In a fourth aspect, the first storage tank has, on the floor surface, one to five rows of the first holes arranged in the first orthogonal direction in a direction intersecting the first orthogonal direction, The second storage tank has, on the floor surface, one to five rows of the second holes arranged in the second orthogonal direction in a direction intersecting the second orthogonal direction, A method for producing an agglomerate of natural rubber according to a third aspect. A fifth aspect is the method for producing a natural rubber agglomerate according to any one of the first to fourth aspects, wherein the mixture has a pH of 4.2 or more and 5.2 or less immediately after the treated natural rubber latex and the acid come into contact with each other at the contact portion. A sixth aspect is the method for producing a natural rubber agglomerate according to any one of the first to fifth aspects, wherein the pretreatment step is a step of pretreating the natural rubber latex with at least one of a surfactant and an enzyme to decompose at least one of proteins and lipids, thereby obtaining the treated natural rubber latex.

[0009] A seventh aspect of the present invention is a process for producing a natural rubber latex-containing product, comprising: a first flow path through which the treated natural rubber latex flows; a second flow path through which the acid flows; a contact section where the treated natural rubber latex flowing through the first flow path comes into contact with the acid flowing through the second flow path to produce a mixture of the treated natural rubber latex and the acid; a falling portion through which the mixture falls vertically downward from the contact portion; a third flow path that is disposed vertically below the contact portion and through which the mixture that has fallen through the falling portion flows; a receiving container into which the mixture that has flowed through the third flow path flows, The apparatus for producing a natural rubber agglomerate is capable of obtaining an agglomerate formed by agglomerating the treated natural rubber latex and the acid. An eighth aspect of the present invention is a method for producing a natural rubber latex-removing apparatus comprising: a first storage tank that stores the treated natural rubber latex, the first storage tank having a plurality of first holes in a floor surface, the first storage tank allowing the treated natural rubber latex to fall from the first holes toward the first flow path; a second storage tank that stores the acid, has a plurality of second holes in a floor surface, and allows the acid to fall from the second holes toward the second flow path; The apparatus for producing a natural rubber agglomerate according to a seventh aspect, In a ninth aspect, the first storage tank has a plurality of the first holes on the floor surface, the first holes are arranged in a first orthogonal direction that is orthogonal to the direction in which the treated natural rubber latex flows through the first flow path, the average hole diameter of the first holes is 1 mm or more and 10 mm or less, and the average interval between the first holes in the first orthogonal direction is 10 mm or more and 50 mm or less, the second reservoir tank has a plurality of the second holes on the floor surface, the second holes are arranged in a second orthogonal direction perpendicular to the direction in which the acid flows through the second flow path, the second holes have an average hole diameter of 1 mm or more and 10 mm or less, and the average interval between the second holes in the second orthogonal direction is 10 mm or more and 50 mm or less; 10 is an apparatus for producing a natural rubber agglomerate according to an eighth embodiment. In a tenth aspect, the first storage tank has, on the floor surface, one to five rows of the first holes arranged in the first orthogonal direction in a direction intersecting with the first orthogonal direction, The second storage tank has, on the floor surface, one to five rows of the second holes arranged in the second orthogonal direction in a direction intersecting the second orthogonal direction, An apparatus for producing a natural rubber agglomerate according to a ninth aspect. [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 unagglomerated 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 pretreatment step of decomposing at least one of proteins and lipids in natural rubber latex by pretreatment to obtain treated natural rubber latex; a mixing step of bringing the treated natural rubber latex flowing through a first flow path into contact with an acid flowing through a second flow path at a contact point between the first flow path and the second flow path to obtain a mixture of the treated natural rubber latex and the acid; and an aggregation step of dropping the mixture toward a third flow path located vertically below the contact point, and then pouring the mixture through the third flow path into a receiving container to obtain an agglomerate of the treated natural rubber latex and the acid.

[0015] A natural rubber agglomerate manufacturing apparatus according to an embodiment of the present disclosure includes a first flow path through which treated natural rubber latex flows, a second flow path through which acid flows, a contact section where the treated natural rubber latex flowing through the first flow path comes into contact with the acid flowing through the second flow path to obtain a mixture of the treated natural rubber latex and the acid, a drop section through which the mixture falls vertically downward from the contact section, a third flow path disposed vertically below the contact section and through which the mixture that has fallen through the drop section flows, and a receiving container into which the mixture that has flowed through the third flow path flows, and is capable of obtaining an agglomerate of the treated 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 tank 21 serving as a first storage tank for storing treated natural rubber latex 2 and having a plurality of first holes 210 in its floor, a second tank 22 serving as a second storage tank for storing acid 4 and having a plurality of second holes 220 in its floor, a first gutter 41 forming a first flow path through which the treated natural rubber latex 2 flows, a second gutter 42 forming a second flow path through which the acid 4 flows, a contact section 40 where the treated natural rubber latex 2 having flowed through the first flow path comes into contact with the acid 4 having flowed through the second flow path, a drop section 50 through which the mixture falls from the contact section 40, a slider 43 disposed vertically below the contact section 40 and forming a third flow path through which the mixture having flowed through the drop section 50 flows, and a receiving container 74 into which the mixture having flowed through the third flow path flows. For example, formic acid is used as the acid 4.

[0019] A first storage container 11 that stores treated natural rubber latex 2 is provided upstream of the first tank 21. A pH meter 61 that monitors the pH of the treated 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 at the top of the first storage container 11. The pH adjustment nozzle 14 has an adjustment valve 14a. A stirrer 18 for stirring the treated 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 treated natural rubber latex 2 in the first storage container 11 in accordance with the pH monitored by the pH meter 61, and the treated natural rubber latex 2 is stirred by the stirrer 18, thereby controlling the pH of the treated natural rubber latex 2 within a certain range.

[0020] The treated 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 treated natural rubber latex 2 poured into the first tank 21 can be controlled by the adjusting valve 31a.

[0021] The first tank 21 has a plurality of first holes 210 on its floor surface. The treated 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 (first falling step). The state of the treated 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 continuously). The amount of treated 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 treated natural rubber latex 2 from the first tank 21 through the first hole 210, the amount of treated natural rubber latex 2 supplied to the first gutter 41 that forms the first flow path can be adjusted.

[0022] 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 treated 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 treated 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. Since the amount of treated natural rubber latex 2 supplied from the first tank 21 to the first gutter 41 can be adjusted, the amount of treated natural rubber latex 2 flowing over the inclined surface 41a of the first gutter 41 and reaching the contact section 40 can also be adjusted.

[0023] 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.

[0024] The second tank 22 has a plurality of second holes 220 on its floor. 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 (second falling process). 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, but may be, for example, thin streaks (i.e., a state in which a small amount of liquid falls continuously). 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.

[0025] 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. Since the amount of acid 4 supplied from the second tank 22 to the second gutter 42 can be adjusted, the amount of acid 4 flowing over the inclined surface 42a of the second gutter 42 and reaching the contact section 40 can also be adjusted.

[0026] The treated 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 mixture (mixing process). In the embodiment of the present disclosure, it is possible to appropriately adjust both the amount of treated natural rubber latex 2 that flows up the inclined surface 41 a of the first gutter 41 to reach the contact section 40 and the amount of acid 4 that flows up the inclined surface 42 a of the second gutter 42 to reach the contact section 40. In other words, it is possible to bring appropriate amounts of treated natural rubber latex 2 and acid 4 into contact with each other in the contact section 40.

[0027] The mixture obtained by contacting the treated 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).

[0028] The slider 43 has an inclined surface 43a that slopes toward the receiving container 74. The inclined surface 43a forms a third flow path. The mixture that falls from the contact section 40 through the falling section 50 in the direction of arrow C reaches the inclined surface 43a of the slider 43. Then, the mixture that has reached the slider 43 flows on the inclined surface 43a in the inclined direction (i.e., the direction of arrow D) and flows into the receiving container 74. A pH meter 62 that monitors the pH of the mixture flowing in the direction of arrow D is disposed on the inclined surface 43a.

[0029] In the mixture obtained by contacting the treated natural rubber latex 2 with the acid 4 in the contact section 40, aggregation of the treated 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 enters the receiving container 74, and after it has entered the receiving container 74, aggregates 72 of the treated natural rubber latex 2 and the acid 4 are formed in the mixture (aggregation step), and the aggregates 72 are stored in a pool 70 in the receiving container 74. The pool 70 contains a liquid other than the treated natural rubber latex 2 and the acid 4 (e.g., serum). A pH meter 63 for monitoring the pH is disposed in the pool 70 in the receiving container 74.

[0030] 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 treated natural rubber latex to obtain a natural rubber agglomerate, the treated natural rubber latex that has not been agglomerated is further treated with an acid. The reason why this effect is achieved will be explained below.

[0031] A conventional method for obtaining natural rubber coagulates involves adding acid to treated natural rubber latex, which has been prepared by pretreating to decompose at least one of the proteins and lipids in natural rubber latex. However, when acid is added to the treated natural rubber latex, coagulation proceeds rapidly, resulting in non-uniform coagulates. This means that uncoagulated natural rubber latex and acid remain in the mixture, resulting in a decrease in the yield of coagulated natural rubber. This is thought to be because coagulation proceeds rapidly at the point where the treated natural rubber latex and acid come into contact in the mixture, and the uncoagulated acid is incorporated into the coagulated portion, leaving the acid and treated natural rubber latex remaining uncoagulated. Therefore, there is a need to prevent the uncoagulated treated natural rubber latex and acid from remaining when acid is added to the treated natural rubber latex to obtain natural rubber coagulates.

[0032] In contrast, in the method and apparatus for producing a natural rubber agglomerate according to the embodiments of the present disclosure, the amounts of treated natural rubber latex and acid supplied to the contact section can be adjusted. That is, appropriate amounts of treated natural rubber latex and acid can be brought into contact with each other in the contact section. By bringing appropriate amounts of treated natural rubber latex and acid into contact with each other, even if coagulation proceeds rapidly, the amount of uncoagulated acid that is incorporated into the resulting agglomerates can be reduced. This allows the coagulation reaction between the treated natural rubber latex and acid to be promoted continuously and efficiently. Furthermore, the mixture of the treated natural rubber latex and the acid mixed in the contact section falls from the contact section into the third flow path, thereby allowing the mixture to be mixed more uniformly. This more uniform mixing of the two promotes the reaction between the treated natural rubber latex and the acid. From this perspective, the amount of unaggregated acid that is incorporated into the aggregates can be reduced.

[0033] As described above, the method and apparatus for producing a natural rubber agglomerate according to the embodiments of the present disclosure can suppress the remaining unagglomerated natural rubber latex and acid when adding acid to treated natural rubber latex to obtain a natural rubber agglomerate, thereby suppressing variation in the quality of the obtained natural rubber agglomerate and increasing the yield.

[0034] pH The pH of the mixture immediately after contact between the treated natural rubber latex and the acid at the contact section (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 within the above range, the coagulation of the treated natural rubber latex and the acid proceeds smoothly, and the amount of uncoagulated treated natural rubber latex and the remaining acid is further reduced. It is even more preferable that the pH of the mixture immediately after contact between the treated natural rubber latex and the acid is 4.4 or more and 5.0 or less.

[0035] The pH of the mixture immediately after the treated natural rubber latex and the acid have come into contact can be adjusted by the pH of the treated natural rubber latex (for example, the pH of treated natural rubber latex 2 stored in first storage container 11 in FIG. 1 ), the pH of the acid (for example, the pH of acid 4 stored in second storage container 12 in FIG. 1 ), and the amount of treated natural rubber latex and acid supplied to the contact section (for example, this refers to the amount of treated natural rubber latex 2 and acid 4 supplied to contact section 40 in FIG. 1 . Specifically, the amount of treated natural rubber latex 2 dropping from first holes 210 can be adjusted by the diameter of first holes 210 and the spacing between first holes 210, and the amount of acid 4 dropping from second holes 220 can be adjusted by the diameter of second holes 220 and the spacing between second holes 220). The pH of the treated natural rubber latex is not particularly limited, but is preferably 9.0 or higher from the viewpoint of maintaining a stable state without coagulation. The pH of the acid is also not particularly limited, but is preferably 1.0 or higher, more preferably 2.0 or higher, from the viewpoint of ensuring appropriate dispersion of the acid and mixing a sufficient amount of liquid to adjust the pH of the mixture to 4.7±0.5 during coagulation.

[0036] First and second holes The first storage tank preferably has a plurality of first holes in its floor surface, and the first holes are preferably arranged in a first orthogonal direction perpendicular to the direction in which the treated natural rubber latex flows through the first flow path. That is, as shown in Fig. 1, the first tank 21 preferably has a plurality of first holes 210 in its floor surface, and the first holes 210 are preferably arranged in a first orthogonal direction (i.e., the direction of arrow E) perpendicular to the direction in which the treated natural rubber latex 2 flows through the first flow path on the inclined surface 41a of the first gutter 41 (i.e., the direction of arrow A). From the viewpoint of appropriately adjusting the amount of treated natural rubber latex supplied to the contact section to suppress the remaining unaggregated treated natural rubber latex and acid, the average hole diameter of the first holes and the average spacing of the first holes in the first orthogonal direction are preferably within the following ranges. Average diameter of the first hole: 1 mm or more and 10 mm or less (more preferably 1 mm or more and 5 mm or less) Average spacing of the first holes in the first orthogonal direction: 10 mm or more and 50 mm or less (more preferably 15 mm or more and 30 mm or less)

[0037] The second storage tank preferably has a plurality of second holes 220 on its floor surface, and the second holes are preferably arranged in a second orthogonal direction perpendicular to the direction in which the acid flows through the second flow path. That is, as shown in Fig. 1, the second tank 22 preferably has a plurality of second holes 220 on its floor surface, and the second holes 220 are preferably arranged in a second orthogonal direction (i.e., the direction of arrow E) perpendicular to the direction in which the acid 4 flows through the second flow path on the inclined surface 42a of the second gutter 42 (i.e., the direction of arrow B). From the viewpoint of suppressing the remaining unaggregated treated natural rubber latex and acid by appropriately adjusting the amount of acid supplied to the contact portion, the average pore size of the second holes and the average spacing of the second holes in the second orthogonal direction preferably fall within the following ranges. Average diameter of the second holes: 1 mm or more and 10 mm or less (more preferably 1 mm or more and 5 mm or less) Average spacing of second holes in the second orthogonal direction: 10 mm or more and 50 mm or less (more preferably 15 mm or more and 30 mm or less)

[0038] The average pore size of the first holes is calculated by measuring the maximum diameter of each of the first holes arranged on the floor surface of the first storage tank and taking the arithmetic mean value of the measured diameters. The average pore size of the second holes is calculated in the same manner. The average spacing of the first holes in the first orthogonal direction is calculated by measuring the spacing between adjacent first holes (specifically, the distance from the center point of one first hole to the center point of the adjacent first hole) in the first orthogonal direction (the direction of arrow E in Figure 1) on the floor of the first storage tank for all pairs of adjacent first holes, and calculating the arithmetic mean value. The average spacing of the second holes in the second orthogonal direction is calculated in the same way.

[0039] From the viewpoint of efficiently promoting the coagulation reaction between the treated natural rubber latex and the acid, the first storage tank preferably has one to five rows of first holes (rows of first holes) arranged in the first orthogonal direction on the floor surface in a direction intersecting the first orthogonal direction (the direction of arrow F in FIG. 1). The first tank 21 shown in FIG. 1 has three rows of first holes 210 in the direction of arrow F. From the viewpoint of efficiently promoting the coagulation reaction between the treated natural rubber latex and the acid, the second storage tank preferably has one to five rows of second holes (rows of second holes) arranged in the second orthogonal direction on the floor surface in a direction intersecting the second orthogonal direction (the direction of arrow F in FIG. 1). The second tank 22 shown in FIG. 1 has three rows of second holes 220 in the direction of arrow F.

[0040] 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 produces coagulates upon reaction with acid can be used. In the method for producing a natural rubber coagulate according to the embodiments of the present disclosure, a pretreatment step is performed on the natural rubber latex to decompose at least one of proteins and lipids (preferably both proteins and lipids) to obtain treated natural rubber latex, from the viewpoints of reducing odor in the latex and improving processability. Furthermore, the apparatus for producing a natural rubber coagulate according to the embodiments of the present disclosure uses treated natural rubber latex in which at least one of proteins and lipids in the natural rubber latex has been decomposed by pretreatment. Methods for obtaining treated 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 before treatment with at least one of a surfactant and an enzyme, a method of saponifying natural rubber latex before treatment (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, treated natural rubber latex treated with at least one of a surfactant and an enzyme is preferred.

[0041] Examples of natural rubber latex (natural rubber latex before treatment) include tapped natural rubber latex itself, latex stabilized by adding an alkali such as ammonia, and concentrated natural rubber latex obtained by centrifugal separation, and examples of these latexes have a rubber concentration (Dry rubber content; DRC) of 5% by mass or more in terms of solid content.

[0042] The surfactants that can be used to obtain treated natural rubber latex in which at least one of proteins and lipids has been decomposed are not particularly limited as long as they reduce the amount of non-rubber components such as proteins in the natural rubber, and examples thereof 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. The enzymes that can be used to obtain treated natural rubber latex in which at least one of proteins and lipids has been decomposed are not particularly limited, as long as they reduce the amount of non-rubber components, such as proteins, in the natural rubber, and examples thereof include protease enzymes such as papain and alcalase, and lipase enzymes. These can be used alone or in combination of two or more. Preferably, protease enzymes and lipase enzymes are used in order to reduce branching in the natural rubber.

[0043] These surfactants and enzymes can be used alone or in combination of two or more. From the viewpoint of the stability of the treated 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), alkylbenzene 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.

[0044] As a means for treating natural rubber latex (natural rubber latex before treatment) by adding at least one of a surfactant and an enzyme, for example, the target natural rubber mixture can be obtained by adding at least one of a surfactant and an enzyme to the collected natural rubber latex before coagulation.

[0045] 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, branching can be reduced without causing adverse effects such as a decrease in the physical properties of the rubber.

[0046] The mixture of treated natural rubber latex and acid may further contain a natural rubber serum component. The natural rubber serum component contains useful components, such as inositol, carbohydrates, proteins such as α-globulin, sugars, ammonia sources, minerals, glutathione, enzymes, and nucleic acids, which also have heat-resistant anti-aging effects on rubber components. The inclusion of this natural rubber serum component can provide heat-resistant anti-aging effects and enable effective use of natural rubber resources. For example, serum obtained from centrifuged natural rubber latex or its coagulated product can be used as this natural rubber serum component. The amount of natural rubber serum component added is preferably 2 parts by mass or more, more preferably 5 to 30 parts by mass, per 100 parts by mass of the dry content of treated natural rubber latex, calculated as solids.

[0047] ·acid The acid that can be added to the treated natural rubber latex to obtain the coagulate includes, for example, formic acid, acetic acid, propionic acid, sulfuric acid, etc. Formic acid is particularly preferred.

[0048] From the viewpoint of suppressing the remaining unaggregated treated 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 treated natural rubber latex comes into contact with the acid at the contact portion (the pH measured by pH meter 62 arranged on inclined surface 43 a in FIG. 1) falls within the aforementioned range.

[0049] 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 after drying, 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.

[0050] The natural rubber obtained by drying the natural rubber agglomerate according to an 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 obtained by drying the natural rubber agglomerate according to an embodiment of the present disclosure can be suitably used for various rubber products, including, for example, rubber for tires. [Explanation of symbols]

[0051] 2. Treated natural rubber latex 4. Acid 2a, 4a droplet 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 31a, 32a 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 pretreatment step of decomposing at least one of proteins and lipids in natural rubber latex by pretreatment to obtain treated natural rubber latex; a mixing step of bringing the treated natural rubber latex flowing through a first flow path into contact with the acid flowing through a second flow path at a contact point between the first flow path and the second flow path to obtain a mixture of the treated natural rubber latex and the acid; an agglomeration step of dropping the mixture toward a third flow path that is disposed vertically below the contact portion and pouring the mixture that has flowed through the third flow path into a receiving container to obtain an agglomerate of the treated natural rubber latex and the acid; A method for producing a natural rubber agglomerate comprising:

2. a first dropping step of dropping the treated natural rubber latex from a first storage tank that stores the treated natural rubber latex and has a first hole in a floor surface thereof through the first hole toward the first flow path; a second dropping step of dropping the acid from a second storage tank that stores the acid and has a second hole in its floor toward the second flow path through the second hole; The method for producing the natural rubber agglomerate according to claim 1, comprising:

3. the first storage tank has a plurality of the first holes on the floor surface, the first holes are arranged in a first orthogonal direction that is orthogonal to a direction in which the treated natural rubber latex flows through the first flow path, the first holes have an average hole diameter of 1 mm or more and 10 mm or less, and the average interval between the first holes in the first orthogonal direction is 10 mm or more and 50 mm or less, the second reservoir tank has a plurality of the second holes on the floor surface, the second holes are arranged in a second orthogonal direction perpendicular to the direction in which the acid flows through the second flow path, the second holes have an average hole diameter of 1 mm or more and 10 mm or less, and the average spacing between the second holes in the second orthogonal direction is 10 mm or more and 50 mm or less; A method for producing the natural rubber agglomerate according to claim 2.

4. the first storage tank has, on the floor surface, one to five rows of the first holes arranged in the first orthogonal direction in a direction intersecting the first orthogonal direction; The second storage tank has, on the floor surface, one to five rows of the second holes arranged in the second orthogonal direction in a direction intersecting the second orthogonal direction. A method for producing the natural rubber agglomerate according to claim 3.

5. 2. The method for producing a natural rubber agglomerate according to claim 1, wherein the mixture has a pH of 4.2 or more and 5.2 or less immediately after the treated natural rubber latex and the acid come into contact with each other at the contact portion.

6. 2. The method for producing a natural rubber agglomerate according to claim 1, wherein the pretreatment step is a step of pretreating the natural rubber latex with at least one of a surfactant and an enzyme to decompose at least one of proteins and lipids, thereby obtaining the treated natural rubber latex.

7. a first flow path through which the treated natural rubber latex flows; a second flow path through which the acid flows; a contact section where the treated natural rubber latex flowing through the first flow path comes into contact with the acid flowing through the second flow path to produce a mixture of the treated natural rubber latex and the acid; a falling portion through which the mixture falls vertically downward from the contact portion; a third flow path disposed vertically below the contact portion and through which the mixture that has fallen through the falling portion flows; a receiving container into which the mixture that has flowed through the third flow path flows, The apparatus for producing a natural rubber agglomerate is capable of obtaining an agglomerate obtained by agglomerating the treated natural rubber latex and the acid.

8. a first storage tank that stores the treated natural rubber latex, the first storage tank having a plurality of first holes in a floor surface, and the treated natural rubber latex falling from the first holes toward the first flow path; a second storage tank that stores the acid, has a plurality of second holes in a floor surface, and allows the acid to fall from the second holes toward the second flow path; The apparatus for producing a natural rubber agglomerate according to claim 7, comprising:

9. the first storage tank has a plurality of the first holes on the floor surface, the first holes are arranged in a first orthogonal direction that is orthogonal to a direction in which the treated natural rubber latex flows through the first flow path, the first holes have an average hole diameter of 1 mm or more and 10 mm or less, and the average interval between the first holes in the first orthogonal direction is 10 mm or more and 50 mm or less, the second reservoir tank has a plurality of the second holes on the floor surface, the second holes are arranged in a second orthogonal direction perpendicular to the direction in which the acid flows through the second flow path, the second holes have an average hole diameter of 1 mm or more and 10 mm or less, and the average spacing between the second holes in the second orthogonal direction is 10 mm or more and 50 mm or less; The apparatus for producing the natural rubber agglomerate according to claim 8.

10. the first storage tank has, on the floor surface, one to five rows of the first holes arranged in the first orthogonal direction in a direction intersecting the first orthogonal direction; The second storage tank has, on the floor surface, one to five rows of the second holes arranged in the second orthogonal direction in a direction intersecting the second orthogonal direction. The apparatus for producing the natural rubber agglomerate according to claim 9.

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