JP2013199528A - Wet master batch containing silica and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a wet master batch containing silica in which silica is high dense and handleability is favorable; and a manufacturing method to obtain the same efficiently.SOLUTION: A manufacturing method includes: a process in which a silica dispersion is prepared; a process in which a mixture liquid including the silica dispersion, an oil emulsion, and a polymer latex is prepared; and a process in which the mixture liquid is not coagulated but is performed by spray drying, wherein an oil content of the oil emulsion is adjusted to be 10-80 mass% based on a silica content of the silica dispersion. In addition the manufacturing method is used.

Description

  The present invention relates to a silica-containing wet masterbatch used for compounding in the production of various rubber products such as tires and a method for producing the same. More specifically, the silica-containing wet masterbatch has a good particle state and the like even in high silica filling. The present invention relates to a wet masterbatch and a production method by which it can be efficiently obtained.

  Conventionally, as a rubber production method excellent in dispersibility and processability, a rubber latex and a filler slurry such as carbon black and silica are mixed, and a mixture of the rubber and the filler is solidified by a coagulant such as an acid. A method using a so-called wet masterbatch is used. The wet masterbatch obtained by this method is a filler for the rubber component compared to so-called dry kneading or dry kneading, in which a filler is added to the rubber component together with other additives using a kneading roll or the like. It has the advantages of excellent dispersibility and excellent rubber properties after vulcanization (breaking strength, abrasion resistance, etc.).

  However, in the manufacturing process of the wet masterbatch, the coagulated product obtained by coagulating the mixed solution of rubber latex and filler slurry needs to be further separated and washed, dehydrated and dried. However, there was a problem that the number of processes was large and the production efficiency was low. In addition, when a silica-containing wet masterbatch is produced by this method, the silica surface has a hydrophilic silanol group (Si-OH) and is therefore difficult to be incorporated into the rubber component. ) And the addition of a large amount of surfactant, there is a problem that high filling is difficult.

  As a related masterbatch production method, Patent Document 1 discloses that a polymer composition containing a filler is produced by drying a rubber solution and a filler solution by pulse combustion. This is aimed at preventing thermal deterioration of the rubber, and has proposed that the temperature of the drying chamber be set to 140 ° C. or lower. However, high filling of silica is not described, and the filler filling rate of 50 phr is shown in the examples. However, it is difficult to use blends with other polymers at this filling rate.

  Patent Document 2 discloses that natural rubber latex and silica contain a compound having a quaternary ammonium salt structure and a carboxyl ion in the molecule (amphoteric surfactant) and spray-dried. This is intended to provide a silica-containing rubber composition excellent in low heat build-up. However, this document does not describe high silica loading.

  Patent Document 3 discloses that a latex and silica are co-coagulated and then spray-dried, and this is intended to obtain a rubber-silica composite fine powder having an average particle size of 50 to 500 μm. Here, the silica filling rate is 50 to 500 phr (200 to 300 phr in the examples), which is as high as possible. However, since the fine powder is obtained, it is practically the same as adding a normal filler as a formulation. Not right.

JP 2005-298672 A JP 2009-084491 A JP 2003-286369 A

  The present invention has been made in view of the above, and provides a silica-containing wet masterbatch having a high silica filling and a good masterbatch grain state and the like, and a production method for efficiently obtaining the masterbatch. With the goal.

  In order to solve the above problems, the method for producing a silica-containing wet masterbatch of the present invention includes a step of preparing a silica dispersion, a step of preparing an oil emulsion, the silica dispersion, an oil emulsion, and a polymer latex. And a step of spray-drying the mixed solution without coagulation, and adjusting the oil content of the oil emulsion to 10 to 80% by mass with respect to the silica content of the silica dispersion. It shall be.

  In the above production method, a styrene-butadiene rubber latex can be suitably used as the polymer latex.

  Moreover, it is preferable that content of the silica in the said silica dispersion liquid is 5-40 mass%.

  Moreover, it is preferable that the silica content of the said liquid mixture is 100 phr or more.

  The silica-containing wet masterbatch of the present invention is obtained by the production method of the present invention.

  According to the present invention, a silica-containing wet masterbatch having a good masterbatch grain state and the like even with a high silica content, and thus excellent handling properties, and thus easy to use for blending can be obtained easily and efficiently.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

  As described above, the method for producing a silica-containing wet masterbatch of the present invention includes (1) a step of preparing a silica dispersion, (2) a step of preparing an oil emulsion, (3) a silica dispersion, an oil emulsion, It comprises at least a step of preparing a mixed solution from the polymer latex, and (4) a step of spray-drying the mixed solution without coagulation. Each step will be described below.

(1) Preparation of silica dispersion In this step, silica is dispersed in a dispersion medium such as water to form a slurry.

  The silica to be used is not particularly limited, and examples include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate and the like. There is no particular need for silica surface treatment or addition of a surfactant.

  As for content of the silica in a slurry, 5-40 mass% is preferable. If it exceeds 40% by mass, the viscosity will increase, causing problems with liquid flowability, and dispersion processing may become difficult. If it is less than 5% by mass, there is no problem effectively, but productivity is inferior and it is economically disadvantageous.

  Various known dispersion methods and apparatuses can be used for the dispersion operation without any particular limitation.

  Colloidal silica can also be used as a silica dispersion instead of or together with the silica slurry.

(2) Preparation of oil emulsion In this step, oil, water and an emulsifier are mixed and stirred to form an emulsion.

  The oil to be used is not particularly limited and may be appropriately selected depending on the purpose of use. Examples thereof include mineral oil (aroma oil, “X-140” manufactured by JOMO).

  The emulsifier is not limited to these, but as an example, a surfactant (“Emulgen 105” manufactured by Kao Corporation), refined cellulose, silica, or the like can be used.

  The oil content is preferably 10 to 80% by mass relative to silica. When the oil content is less than 10% by mass, high silica filling becomes difficult. When the oil content exceeds 80% by mass, over-adhesion occurs, and handling properties may be deteriorated.

  The ratio of oil to water in preparing the emulsion is not limited to this, but as a guideline, the mass ratio of oil to water is oil: water = 70: 30 to 30:70. The amount of the emulsifier may be appropriately selected depending on the emulsifier used, but is usually about 0.5% by mass with respect to the oil. Emulsification can be performed according to a conventional method using a known method and apparatus.

(3) Preparation of mixed liquid of silica dispersion, oil emulsion, and polymer latex In this step, the silica dispersion, oil emulsion, and polymer latex obtained above are mixed and used for spray drying in the next step. A mixed solution is produced.

  As the polymer latex, it is preferable to use a styrene-butadiene rubber (SBR) latex in view of easiness of spray drying and the grain state of the obtained master batch. Since natural rubber (NR) latex is easily coagulated, there is a problem that the coagulum is easily clogged in the vicinity of the discharge port due to the structure of the spray dryer used in the spray drying process. There are also concerns about molecular chain scission when exposed to high temperatures.

  In the present invention, it is considered that the deterioration of handling property (high powderization and high viscosity of the masterbatch) due to high silica filling is improved by simultaneously mixing the polymer solution, the silica dispersion, and an appropriate amount of oil emulsion.

  As for the solid content (active ingredient) density | concentration of a liquid mixture, 10-30 mass% is preferable. When this solid content concentration exceeds 30% by mass, the discharge port tends to be clogged, and the drying efficiency may be reduced. On the other hand, if it is less than 10% by mass, the production efficiency is lowered, which is economically disadvantageous.

  Moreover, since the silica content of a liquid mixture becomes the silica content rate of a masterbatch as it is, it is preferable that it is 100 phr or more. When the silica content is less than 100 phr, the silica filling rate tends to be insufficient when blended as a blend, and the practicality is low. The upper limit of the silica content is not particularly limited, but is usually about 500 phr.

(4) Spray drying of liquid mixture In this step, the liquid mixture of the polymer latex, the oil emulsion and the silica dispersion liquid is directly dried by spray drying without coagulation.

  In the present invention, a masterbatch with high silica filling is obtained by spray-drying the above mixed solution. In addition, since only moisture is instantaneously removed from the above mixture by spray drying, there is no need for silica surface treatment (hydrophobization) or the addition of a large amount of surfactant. The effect that it is obtained is also acquired.

  Furthermore, the number of steps can be greatly reduced as compared with a production method using steps of mixing, coagulation, solid-liquid separation, washing, dehydration, and drying when a normal coagulation method is used. Therefore, it is advantageous also in terms of production efficiency and cost.

  The apparatus used for spray drying is not particularly limited, and a known apparatus can be used. The temperature setting in the drying chamber is preferably 150 to 200 ° C. in view of the prevention of component deterioration and the drying efficiency.

  In the silica-containing wet masterbatch according to the present invention, as long as it does not depart from the purpose of the present invention, in addition to the above components, zinc white, stearic acid, anti-aging agent, WAX, Compounding chemicals such as a vulcanizing agent and a vulcanization accelerator can be blended. When blending these compounding chemicals, it is preferable to liquefy like the above silica and oil, blend into the above mixed solution, and use for spray drying.

  The silica-containing wet masterbatch obtained by the above production method can be used, for example, as a compounding component of a vulcanized rubber composition for tires and the like, and the rubber composition is added at, for example, 140 to 180 ° C. according to a conventional method. By subjecting it to sulfur molding, a desired rubber product can be formed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. The blending ratio shown below is based on mass (“parts by mass”, “mass%”, etc.) unless otherwise specified.

[Examples and Comparative Examples]
A mixed solution was prepared according to the formulation shown in Table 1 below, and dried by the method shown in the table to prepare a silica-containing wet masterbatch. Details, operating conditions, etc. of each formulation in Table 1 are as follows.

<SBR latex>
“RODEX” manufactured by JSR Corporation
SBR content: 50% by mass
<Silica dispersion>
Silica: “Nip Seal AQ” manufactured by Tosoh Silica Corporation
Silica content in slurry: 15% by mass
Dispersing device: rotor stator type dispersing device <oil emulsion>
Oil: “X-140” manufactured by Japan Energy Co., Ltd.
Oil content in emulsion: 50% by mass
Emulsifier: “Emulgen 105” manufactured by Kao Corporation
Emulsifying material amount: 0.5% by mass
Emulsifying device: Rotor stator type dispersing device

<Preparation of liquid mixture>
The silica dispersion, oil emulsion, and polymer latex were diluted and prepared so that each active ingredient had a ratio shown in Table 1, and then stirred with a propeller blade.

<Spray drying>
The mixture was dried instantaneously (several seconds or less) with a spray drier (manufactured by Yamato Scientific Co., Ltd., spray dryer “ADL311S”) in which the inlet temperature of the drying chamber was set to the temperature shown in Table 1.

<Coagulation drying>
The mixed solution was coagulated by adding formic acid as a coagulant, and the coagulated product was collected, washed with water, dehydrated, and dried with a hot air circulation dryer.

  About each obtained masterbatch, grain size, a grain state, and the adhesion state were investigated, and the handleability was investigated with the following method. The silica content was examined by thermogravimetry (TGA). The results are shown in Table 1.

<Evaluation of master batch>
-Grain size A sieve shaker was used and examined under the following conditions.
Equipment: Electromagnetic sieve shaker (AS200 digit, manufactured by Lecce)
Sieve: Conforms to JIS Z8801-1 Sieve opening: 1.00mm, 2.00mm, 3.25mm, 4.00mm, 4.75mm, 5.60mm
Shaking condition: amplitude 2.00 mm, time 3 minutes Judgment condition: The range in which the weight of the classified sample occupies 90% or more of the total input amount was shown. For example, when 90% or more of the input sample remains on a sieve having a mesh opening of 2.00 mm, “2 to 3.25 mm” is set, and each sieve having a mesh opening of 3.25 mm, 4.00 mm, and 4.75 mm. When it remained on each, it was set as "3.25-5.6mm".

-Grain state Judgment was made from the grain size according to the following criteria.
<1 mm (less than 1 mm): powdery 1-3.25 mm: small granularity 3.25-5.6 mm: granular 5.6 mm <(larger than 5.6 mm): massive

・ Handling property Evaluation was made based on the following criteria from the size, state, and adhesion state of the grains.
○: Good workability ▲: Workability is slightly inferior ×: Difficult to handle because it is powdery and easily scatters, is sticky, or is massive

  As can be seen from the results shown in Table 1, all of the master batches in the examples have a high silica content of 100 phr or more and have good grain size, grain state, and adhesive state, and therefore have good handling properties. Met. In particular, Example 6 shows that even when the silica content is as high as 500 phr, a master batch in a good state can be obtained by making each condition such as the oil amount appropriate.

  On the other hand, Comparative Example 1 has no problem as the state of the masterbatch, but since the silica filling amount is low, there is a problem that the silica content is insufficient when considering blending and using other polymers. . In Comparative Example 2, oil is not used and the silica filling amount is 100 phr, and the obtained master batch is powdery and has extremely poor handling properties. Moreover, since the comparative example 3 has insufficient oil amount, it has shown that a powder state is not improved and handling property is not improving. On the other hand, since Comparative Example 4 has an excessive amount of oil, it indicates that handling properties are not improved by excessive adhesion. From these results, it can be seen that the improvement of the state of the masterbatch, that is, the handling property, and the high silica filling can be made compatible by adjusting the oil amount appropriately. In addition, Comparative Example 5 is an example using solidification, and it is shown that high silica filling is difficult and the grain state of the master batch is poor.

  The silica-containing wet masterbatch of the invention can be used as a compounding material for manufacturing various tires such as passenger cars, light trucks, trucks and buses.

Claims (5)

Preparing a silica dispersion;
Preparing an oil emulsion;
A step of preparing a mixed solution containing the silica dispersion, the oil emulsion, and a polymer latex; and a step of spray-drying the mixed solution without coagulation,
The method for producing a silica-containing wet masterbatch, wherein the oil content of the oil emulsion is adjusted to 10 to 80% by mass with respect to the silica content of the silica dispersion. The method for producing a silica-containing wet masterbatch according to claim 1, wherein the polymer latex is a styrene-butadiene rubber latex. Content of the silica in the said silica dispersion liquid is 5-40 mass%. The manufacturing method of the silica containing wet masterbatch of Claim 1 or 2 characterized by the above-mentioned. The method for producing a silica-containing wet masterbatch according to any one of claims 1 to 3, wherein the mixed solution has a silica content of 100 phr or more and 500 phr or less.   The silica containing wet masterbatch obtained by the manufacturing method of any one of Claims 1-4.