JP2009256550A - Method for blending rubber-inorganic filler masterbatch and rubber chemical - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for blending a rubber chemical with a rubber-inorganic filler masterbatch containing an inorganic filler such as carbon black, with which the rubber chemical can be uniformly dispersed in a short time while suppressing occurrence of slippage, even if the rubber chemical is of low melting point or low softening point. <P>SOLUTION: This blending method comprises kneading a rubber chemical with a pellet-like rubber-inorganic filler masterbatch containing a rubber component comprising natural and/or diene-based synthetic rubber and an inorganic filler. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of mixing a rubber / inorganic filler master batch containing a rubber component made of natural rubber and / or a diene synthetic rubber and an inorganic filler such as carbon black, and a rubber chemical. More specifically, a rubber containing an inorganic filler such as carbon black that can suppress the occurrence of slip even in a low melting point or low softening point rubber chemical and can uniformly disperse the rubber chemical in a short time. -It is related with the mixing method of an inorganic filler masterbatch and rubber chemicals.

In the tire industry, it is necessary to efficiently knead a wide range of rubber compounds from soft to super-hard rubber compounds, and the bale (block) rubber is well bitten, making it suitable for kneading a wide variety of materials. A tangential (non-meshing) type kneader (Banbury mixer) in which the rotation radii of the two rotors are independent from each other is mainly used (see Non-Patent Document 1).
Conventionally, the rubber / filler master batch has been put into a kneading machine having a sheet-like or bale-like shape and having the tangential rotor and kneaded with rubber chemicals.
However, when a rubber chemical having a low melting point or a low softening point is used, there is a problem that the melting causes slipping between the rotors of the kneader and between the casings, resulting in a long kneading time.
On the other hand, it is conceivable to apply a meshing rotor suitable for a soft and easy-to-adhere rubber used in industrial rubber and the like and a material that easily slips in a chamber mixed with a large amount of liquid additives. Although suppression is possible, there exists a problem that the kneading | mixing time becomes long.
Therefore, it is necessary to develop an efficient mixing method that suppresses the generation of slip using a kneader having the tangential rotor.

Rubber Industry Handbook <4th Edition> Edited by Japan Rubber Association, page 1074

  Under such circumstances, the present invention suppresses the occurrence of slip even in the case of a rubber chemical having a low melting point or a low softening point, and can disperse the rubber chemical uniformly in a short time. It is an object of the present invention to provide a method for mixing a rubber / inorganic filler master batch containing an inorganic filler and a rubber chemical.

As a result of intensive studies to achieve the above object, the present inventor has found that the object can be achieved by using a rubber / inorganic filler masterbatch having a specific shape or a specific bulk specific gravity. . The present invention has been completed based on such findings.
That is, the present invention is (1) mixing characterized by kneading a rubber component made of natural rubber and / or a diene synthetic rubber and a pellet-like rubber / inorganic filler masterbatch containing an inorganic filler and a rubber chemical. Method,
(2) A rubber component comprising a natural rubber and / or diene synthetic rubber and an inorganic filler and a veil-like rubber / inorganic filler masterbatch having a specific gravity of 0.1 to 0.3 and a rubber chemical are kneaded. A mixing method characterized by
(3) The mixing method of (1) or (2) above, wherein the melting point of the rubber chemical is 80 ° C. or lower, and (4) (1) to (3) above, wherein the kneader is an internal mixer having a tangential rotor. ) Any mixing method,
Is to provide.

  According to the present invention, even when a rubber chemical having a low melting point or a low softening point is used, the occurrence of slip is suppressed, and the rubber / inorganic filling can be uniformly dispersed in a short time. Material masterbatch and rubber chemicals can also provide a mixing method.

  First, as a first embodiment, the mixing method of the present invention includes kneading a rubber component made of natural rubber and / or a diene synthetic rubber, a pellet-like rubber / inorganic filler master batch containing an inorganic filler, and a rubber chemical. Next, as a second embodiment, the mixing method of the present invention has a bulk specific gravity of 0. 0 which includes a rubber component made of natural rubber and / or a diene synthetic rubber and an inorganic filler. 1 to 0.3 veiled rubber / inorganic filler masterbatch and rubber chemicals are kneaded.

[Rubber / inorganic filler masterbatch]
There is no restriction | limiting in particular about the manufacturing method of a rubber | gum and an inorganic filler masterbatch, Although a wet masterbatch or a dry masterbatch is mentioned by the manufacturing method, In the mixing method of this invention, any masterbatch can be used.
<Wet masterbatch>
A wet masterbatch is usually produced using natural rubber latex as a rubber component, and an inorganic filler such as carbon black is well dispersed and excellent rubber properties can be obtained.
This master batch is prepared by (I) a step of adjusting a mixed solution of a natural rubber latex and a dispersion slurry of an inorganic filler, (II) a step of coagulating the mixed solution and taking out the formed coagulated solution, And (III) a step of drying the taken-out coagulum.
In the case of a diene synthetic rubber, a wet masterbatch is obtained through a process similar to that of natural rubber latex by adjusting a mixed liquid of an emulsion obtained by emulsion polymerization (for example, SBR) and a dispersion slurry liquid of an inorganic filler. be able to.

<Dry masterbatch>
The dry masterbatch can be obtained, for example, by mixing a veiled or sheet-like solid rubber component and an inorganic filler using a kneader.
As the kneading machine, a kneading machine usually used in the rubber industry is used. As the kneading machine, a mixing roll, an internal mixer typified by a Banbury mixer, a pressure kneader, a multi-axis kneading extruder that rotates in the same direction or in different directions, and the like are used.
In particular, most of the rubber is supplied in a bale (usually a 35 kg block), and an internal mixer is preferred for kneading such a block-like material.

[Rubber component]
Natural rubber and / or diene synthetic rubber is used as the rubber component used in the rubber / inorganic filler masterbatch. Here, examples of the diene synthetic rubber include polyisoprene synthetic rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like. Is mentioned. The natural rubber and diene synthetic rubber of component (A) may be used alone or in combination of two or more.
In addition, as the natural rubber latex used in the wet masterbatch, any of field latex, ammonia-treated latex, centrifugal concentrated latex, enzyme-treated deproteinized latex, and combinations of the above can be used. .

[Inorganic filler]
Examples of inorganic fillers used in rubber / inorganic filler masterbatches include carbon black, silica, and general formula (I).
mM · xSiOy · zH ₂ O (I)
(In the formula, M represents at least one metal element selected from aluminum, titanium, magnesium and calcium, its oxide or hydroxide, m is 1 to 5, x is 0 to 10, and y is 2) ~ 5, z represents a number of 0 to 10.) Including inorganic compound particles represented by the following formula is also preferably used. Of these, carbon black and silica are preferable, and carbon black is particularly preferable.

<Carbon black>
Examples of carbon black include channel black, furnace black, acetylene black, and thermal black depending on the production method, and any of them can be used. The carbon black preferably has a nitrogen adsorption specific surface area (BET) in the range of 80 to 280 m ² / g. If the BET value is less than 80 m ² / g, the rigidity is insufficient and sufficient wear resistance is difficult to obtain, and if it exceeds 280 m ² / g, the heat generation performance is deteriorated. Considering wear resistance and heat generation performance, a more preferable range of the BET value is 100 to 180 m ² / g. The BET value is a value measured according to ASTM D3037-88. As the carbon black, various carbon blacks such as HAF, ISAF and SAF can be used alone or in combination.

<Silica>
On the other hand, the silica is not particularly limited, and can be appropriately selected from those conventionally used for reinforcing rubber, such as dry method silica and wet method silica (hydrous silicic acid). The silica particles preferably have a nitrogen adsorption specific surface area (BET) in the range of 100 to 280 m ² / g in consideration of wear resistance and heat generation performance. The BET value is a value measured according to ASTM D4820-93 after drying at 300 ° C. for 1 hour.

<Inorganic compound particles>
Examples of the inorganic compound particles represented by the general formula (I) include alumina (Al ₂ O ₃ ), aluminum hydroxide [Al (OH) ₃ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide. (MgO), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), titanium white (TiO _2), titanium black (TiO _2n-1), calcium oxide (CaO), Calcium hydroxide [Ca (OH) ₂ ], aluminum magnesium oxide (MgO.Al ₂ O ₃ ), clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyro Fillite _{(Al2 O 3 · 4SiO 2 ·} H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate _{(Al 2 SiO 5, Al 4} (SiO 4) 3 5H ₂ O etc.), magnesium silicate (Mg ₂ SiO ₄ · MgSiO ₃ etc.), calcium silicate (Ca ₂ SiO ₄ and the like), aluminum silicate calcium _{(Al 2 O 3 · CaO ·} 2SiO 2 etc.), silicic acid Examples thereof include magnesium calcium (CaMgSiO ₄ ). These inorganic compound particles can be used alone or in combination.

When dry blending rubber, carbon black and other inorganic fillers and rubber chemicals by conventional methods, inorganic fillers such as carbon black, oil, and other compounding agents are put into rubber and mixed in a kneader such as a Banbury mixer. (First stage kneading, hereinafter referred to as A kneading process), the rubber compound obtained in the A kneading process is kneaded with vulcanizing agent, vulcanization accelerator, etc. (second stage kneading, hereinafter B kneading process) A vulcanizable rubber composition can be obtained.
In the B kneading step, as described above, a vulcanizing agent and a vulcanization accelerator are blended, so that kneading is usually carried out at a low temperature of 110 ° C. or lower in order to prevent the rubber from being burned.
The mixing method of the present invention suppresses the occurrence of slip, even in the case of a rubber chemical having a low melting point or a low softening point, compared with the above-mentioned rubber / inorganic filler master batch, and makes the rubber chemical uniform in a short time. It is necessary to be dispersed in a normal A kneading step, which is different in that it is a master batch in which a rubber component and an inorganic filler are kneaded in separate steps. Therefore, the shape and characteristics of the masterbatch described later are very important elements in order to sufficiently achieve the excellent effects of the present invention.
The main rubber chemicals applied to the mixing step of the present invention include vulcanizing agents, anti-aging agents (antioxidants) excluding vulcanization accelerators, processing aids, softeners and silane coupling agents (mainly Used when silica is used as the filler).

<Melting point of rubber chemicals>
For example, taking an anti-aging agent as an example, the melting point is as follows.
Examples of the hydroquinone derivative anti-aging agent include 2,5-di-tert-amylhydroquinone (melting point 165 ° C.), 2,5-di-tert-butylhydroquinone (melting point 200 ° C. or more), and the like.
Examples of monophenol antioxidants include 2,6-di-tert-butyl-4-ethylphenol (melting point: 44 to 45 ° C.), butyl hydroxyanisole (melting point: 57 to 60 ° C.), 2,6-di-tert. -Butyl-α-dimethylamino-p-cresol (melting point 94 ° C.), alkylated phenol (melting point 55 ° C.) and the like.
Examples of bis, tris and polyphenol antioxidants include 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol) (melting point of 120 ° C. or higher), 2,2′-methylene-bis- (4 -Methyl-6-cyclohexyl phenol) (melting point 118 ° C. or higher), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol) (melting point 119 ° C. or higher), 4,4′thiobis- ( 6-tert-butyl-3-methylphenol) (melting point of 150 ° C. or higher).
Examples of the imidazole antioxidant include 2-mercaptobenzimidazole (melting point 285 to 290 ° C.), 2-mercaptobenzimidazole zinc salt (decomposition point 300 ° C. or higher), 2-mercaptomethylbenzimidazole zinc salt (decomposition point 270 ° C. or higher). ) And the like.
Amine-based antioxidants include phenyl-α-naphthylamine (melting point 50 ° C. or higher), p- (p-toluenesulfonylamide) -diphenylamine (melting point 135 ° C. or higher), 4,4 ′-(α, αdimethylbenzyl). ) Diphenylamine (melting point 90 ° C. or higher), octylated diphenlamine (melting point 75-100 ° C.), N, N′-diphenyl-p-phenylenediamine (melting point 130 ° C. or higher), N, N′-di-2-naphthyl -P-phenylenediamine (melting point 224 ° C. or higher), N-isopropyl-N′-phenyl-p-phenylenediamine (melting point 70 ° C. or higher), N-phenyl-N ′-(3-methacryloyloxy 2-hydroxypropyl-p -Phenylenediamine (melting point 115 ° C or higher), N, N'-bis (1-methylheptyl) -p-phenylenediamine (pour point 37) 5 ° C.), N, N′-bis (1,4-dimethylpentyl) -p-phenylenediamine (liquid), N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (melting point 44) ° C. or higher), phenyl, octyl-p-phenylenediamine (liquid: freezing point 10 ° C.) and the like.
Thus, even if it takes one melting | fusing point of anti-aging agent, the anti-aging agent which has a melting | fusing point of the wide range of 300 degreeC or more from a liquid in the state of normal temperature is used.
The mixing method of the present invention is effective for rubber chemicals having a melting point of 80 ° C. or lower, particularly 50 ° C. or lower, and can exhibit excellent effects of the present invention.
When the rubber chemical having the melting point is an anti-aging agent, the blending amount per 100 parts by mass of the rubber component in the master batch is preferably 0.5 to 3.0 parts by mass.
The amount of other rubber chemicals can be appropriately determined depending on the performance required of the rubber component.

[Master batch shape]
In the mixing method of the present invention, the shape and characteristics of the master batch are important for dispersing rubber chemicals having a low melting point uniformly and in a short time with respect to the rubber / inorganic filler master batch. A bale-like product having a low bulk density is applied.
<Pelletization>
Normally, rubber is a sticky material, so pelletization is difficult, but the rubber / inorganic filler masterbatch used in the present invention is sticky because it contains a predetermined amount of inorganic filler such as carbon black. Decreases and pelletization is easy. Masterbatch pellets can be produced by a conventional method using a pelletizer.
By making it into pellets, the surface area of the masterbatch is increased and rubber chemicals can be easily dispersed in the masterbatch. Although there is no restriction | limiting in particular about the particle size of a pellet, It is preferable that it is normally 5-20 mm in consideration of dispersion | distribution in the pellet of rubber chemicals.

<Veil of rubber filler masterbatch with bulk specific gravity of 0.1-0.3>
Synthetic rubber used in the tire industry is usually marketed in the form of 35 kg bales and has a specific gravity of about 0.90 to 0.99. The rubber / inorganic filler masterbatch used in the present invention is an inorganic material such as carbon black. Since it contains a filler, its specific gravity exceeds 1 when it is made into a veil similar to synthetic rubber. When a rubber chemical, particularly a low-melting-point rubber chemical is charged into the kneading machine as it is, the melting causes slipping between the rotor of the kneading machine and between the casings, resulting in a longer kneading time. Therefore, it is easy to bite even in a tangential (non-meshing) type kneader (Banbury mixer), and the bulk specific gravity of the veiled master batch is 0.1 to 0.3 in order to uniformly disperse the low melting point rubber chemicals. Must be in range.
In order to make a veil with such a small bulk specific gravity, it is possible to obtain a bale with a bulk specific gravity of 0.1 to 0.3 by adjusting the thickness of the pellet-shaped master batch placed in a bale molding machine and crushed by a press. it can.

[Inner null mixer with tangential rotor]
As described above, the kneading machine can efficiently knead a wide range of rubber compounds from soft to super-hard rubber compounds, has good biting of bale (block) rubber, and has a wide variety of types. It is a Banbury mixer of batch mixing of tangential (non-meshing) type in which the rotation radii of two rotors suitable for kneading of materials are independent from each other. The main kneading action is a shearing action between the tip of the rotor tip and the inner surface of the casing, and has a wide range of application to the compound and has a feature that the material bites in quickly. However, this is not suitable for the blending of rubber in which the inorganic filler is masterbatch and low-melting-point rubber chemicals and oil filling as in this case.
The mixing method of the present invention limits the shape and bulk specific gravity of the master batch to be input to a specific range, and uses a Banbury mixer with a tangential rotor to prevent slipping of low melting point rubber chemicals in a short time. Can be dispersed.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all by these examples.
Production Example 1 Production of Natural Rubber / Inorganic Filler Masterbatch Pellets Manufactured in a conventional manner using a pelletizer. The average particle size of the pellets was 10 mm.

Production Example 2: Manufacture of Natural Rubber / Inorganic Filler Masterbatch Bale with Bulk Specific Gravities of 0.2 and 0.5 Thickness of pressing and crushing pellet-shaped natural rubber / inorganic filler masterbatch into a bale molding machine Was adjusted to produce bales having a bulk specific gravity of 0.2 and 0.5.

Evaluation of kneading state (1). Kneading time Time (minutes) until the rubber temperature reaches 130 ° C.
(2). Slip time The time (minutes) from when the material is put into the kneader until the torque (electric power) rises after the ram weight is lowered.
(3). Electric power peak value The value at the time of the highest torque (electric power) in the torque (electric power) chart.

Example 1 and Comparative Examples 1-2
The bulk specific gravity of the veil of the natural rubber / inorganic filler masterbatch based on the composition shown in Table 1 is two levels of 0.2 and 0.5, and the rotor of the kneader is two levels of tangential and intermeshing types. As a result, kneading was performed in combination, and the kneading time, slip time, and power peak value were evaluated. The evaluation results are shown in Table 1.
Here, the main kneading action of the meshing rotor is to perform a breaking and kneading action between the two rotors, and is suitable for soft rubber having a high oil content.

Example 2 and Comparative Example 1
The shape of the natural rubber / inorganic filler master batch based on the composition shown in Table 1 is two levels of bales and pellets, the rotor of the kneading machine is fixed tangentially and kneaded in combination, kneading time, The slip time and power peak value were evaluated. The evaluation results are shown in Table 1.

［注］
＊１．カーボンブラックＮ１１０：商品名「旭＃９０」、旭カーボン社製
＊２．老化防止剤６ＰＰＤ：商品名「サントフレックス６ＰＰＤ」フレキシス社製；Ｎ−（１，３−ジメチルブチル）−Ｎ’−フェニル−ｐ−フェニレンジアミン、（融点４４℃以上）
＊３．ベール：製造例１により得られたものを用いた。
＊４．ペレット：製造例２により得られたものを用いた。
第１表より次のようなことがわかる。
本発明の実施例１はベールのかさ比重を０．２にすることによって混練時間、スリップ時間、電力ピーク値共に最も優れた値を示している。スリップ時間については、噛み式のローター用いた比較例２も優れた値を示しているが、混練時間が１２分と非常に長くなっていることが分かる。
本発明の実施例２は、マスターバッチをペレットにすることによって比較例１対比、混練時間、スリップ時間共に短く、電力ピーク値について７０％と低いことが分かる。

[note]
* 1. Carbon black N110: trade name “Asahi # 90”, manufactured by Asahi Carbon Co., Ltd. * 2. Anti-aging agent 6PPD: trade name “Santflex 6PPD” manufactured by Flexis; N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (melting point: 44 ° C. or higher)
* 3. Veil: The one obtained in Production Example 1 was used.
* 4. Pellets: those obtained by Production Example 2 were used.
The following can be seen from Table 1.
In Example 1 of the present invention, the kneading time, slip time, and power peak value are the most excellent values by setting the bulk specific gravity of the bail to 0.2. As for the slip time, Comparative Example 2 using a biting rotor also shows an excellent value, but it can be seen that the kneading time is as long as 12 minutes.
In Example 2 of the present invention, it can be seen that by making the master batch into pellets, the comparison with Comparative Example 1, the kneading time and the slip time are short, and the power peak value is as low as 70%.

  The present invention is a rubber containing an inorganic filler such as carbon black that can suppress the occurrence of slip even in a low melting point or low softening point rubber chemical and can uniformly disperse the rubber chemical in a short time. -Provides a method for mixing inorganic filler masterbatch and rubber chemicals, and can be used effectively for an internal mixer having a tangential rotor.

Claims (4)

  A mixing method comprising kneading a rubber component made of natural rubber and / or a diene synthetic rubber, a pellet-like rubber / inorganic filler masterbatch containing an inorganic filler, and a rubber chemical.   It is characterized by kneading a rubber component made of natural rubber and / or a diene-based synthetic rubber and a veil-like rubber / inorganic filler master batch having a bulk specific gravity of 0.1 to 0.3 containing an inorganic filler and rubber chemicals. And mixing method.   The mixing method according to claim 1 or 2, wherein the melting point of the rubber chemical is 80 ° C or lower.   4. The mixing method according to claim 1, wherein the kneader is an internal mixer having a tangential rotor.