JP6444683B2 - Tangential sealed rubber kneader - Google Patents

Description

  The present invention relates to a tangential sealed rubber kneader according to a kneading technique.

  Currently, kneading of natural rubber or synthetic rubber with various compounding chemicals such as carbon black, silica, plasticizer, anti-aging agent or vulcanizing compounding chemical is carried out in a closed kneader.

  Generally, the closed type rubber kneader is Intermix (Mitsubishi Heavy Industries), which is a mesh type closed type rubber kneader, Banbury mixer (made by Kobe Steel), which is a tangential type closed type rubber kneader, and Moriyama pressure kneader (Japan). Spindles) are widely used.

  In such rubber kneading, it is necessary to have the ability to break up agglomerates of compounding chemicals such as carbon black. In particular, acrylic blended with a high reinforcing reinforcing agent such as silica or carbon black having a small particle size. In the case of materials using low-viscosity polymers such as rubber and butyl rubber, a large destructive force is required to destroy and disperse agglomerates such as carbon black, while the viscosity of the polymer that is the source of the destructive force Therefore, it is difficult to knead a reinforcing agent such as carbon black, and it takes a long time to knead or cannot obtain sufficient rubber tensile strength. I cannot escape the decline.

  To solve the above problems, tangential sealed rubber kneaders such as the Banbury mixer and the Moriyama pressure kneader have so far adopted the kneading machines such as the leading angle and the twist angle. Various studies have been conducted on the blade shape, the number of blades, or the tip clearance (gap between the tip of the kneading blade and the inner wall of the kneading tank).

  However, there is no quantitative relationship between the dimensions of the kneading blades comparatively evaluated in these studies, and the evaluation object is the dispersion state and kneading energy of carbon black in the kneaded rubber or the flow of the rubber dough in the kneading machine. Evaluation of the kneading speed is rare because it is biased toward the mixing degree of the compounding agent.

  For this reason, the shape of the kneading blade for sufficiently satisfying the kneading process needs regarding productivity and rubber material quality is not necessarily clarified, and more than 30 minutes are required for kneading acrylic rubber or butyl rubber in the mass production kneading process. However, there is still room for improvement in the current tangential sealed rubber kneader.

JP 59-31369 A

ProcessingConditions in The Batch-Operated Internal Mixer by H.Palmgren RubberChemistry and Technology Vol.48 (1975) P462-494 Structure of Filler-Based Vulcanized Rubber and Structural Change by Mechanical Stimulation Kunihiko Fujimoto, Toshio Nishi The Journal of Rubber Association, Vol. 43, P465-476 Study on structure and physical properties stabilization and three-dimensional stress fatigue in kneading process Kunihiko Fujimoto, Keiji Imai Journal of Rubber Association, Vol. 65, P529-541 Scale-upof Internal Mixers by I.ManasZloczower RubberChemistry and Technology Vol.57 (1984) P48-54 DispersiveMixing in Internal Mixers- ATheoretical Mode Based on Agglomerate Rupture by I.ManasZloczower, A.Nir and Z.Tadmor RubberChemistry and Technology Vol.55 (1994) P1250-1285

  In view of the above points, an object of the present invention is to provide a tangential sealed rubber kneader capable of improving productivity in a rubber kneading step.

  In order to achieve the above object, a tangential sealed rubber kneader according to claim 1 of the present invention includes a rotor that rotates in a kneading tank and a kneading blade that performs kneading operation on the peripheral surface of the rotor. In the hermetic rubber kneader, the biting angle of the kneading blade is more than 55 degrees and less than 90 degrees in order to promote elongation deformation accompanying the swirling motion of the rubber material in the vicinity of the front surface of the kneading blade in the blade rotation direction. Features.

  A tangential type sealed rubber kneader according to claim 2 of the present invention is the tangential type sealed rubber kneader according to claim 1, wherein the tip clearance between the tip of the kneading blade and the inner wall of the kneading tank is 1 mm or more and 3 mm. It is characterized by the following clearance.

  A tangential sealed rubber kneader according to claim 3 of the present invention is the tangential sealed rubber kneader according to claim 1 or 2, wherein the axial length of the kneading blade is the axial length of the rotor. The length is 65% or more and 95% or less.

  Furthermore, the tangential type sealed rubber kneader according to claim 4 of the present invention is the tangential type sealed rubber kneader according to claim 1, 2, or 3, wherein the twist angle of the kneading blade is less than 45 degrees. The angle is set to 5 degrees or more.

The present invention, as a result of intensive investigations on means for overcoming the problems related to productivity, particularly kneading speed, in the conventional tangential sealed rubber kneader,
(A) Estimation of kneading mechanism by association of polymer properties (inflow pressure loss), kneading state (kneading power curve, kneading electricity amount) and kneading speed (bound rubber growth rate up to BIT) (b) Near kneading blade Confirmation of kneading action by observing the flow and deformation state of rubber dough (c) Based on the kneading mechanism, especially by examining the effect of blade shape on kneading speed, especially high reinforcement such as silica and carbon black with small particle size Cutting angle (Leading Angle, Front Angle), tip clearance, and length to improve the kneading speed of difficult-to-knead materials, such as materials using low viscosity polymers such as acrylic rubber and butyl rubber with a reinforcing reinforcing agent And a kneading blade shape of a tangential sealed rubber kneader, such as Twist Angle. Specifically, the swirling motion of the rubber material in the vicinity of the front of the blade rotation direction of the kneading blade (the rotation of the rubber material in the direction opposite to the rotation direction of the kneading blade and the kneading blade shaft along the twist angle of the kneading blade) In order to promote the elongation deformation accompanying the flow of direction), it is proposed to have the following configuration.

(1) Equipped with a kneading blade having a biting angle of more than 55 degrees and less than 90 degrees.
When the biting angle of the kneading blade is 55 degrees or less, the flow of the rubber material in the vicinity of the front surface of the kneading blade becomes close to a shearing flow, and the kneading action is impaired by impairing the rotational motion. If the biting angle of the kneading blade is 90 degrees or more, the blade tip wear becomes large, and it becomes difficult to maintain the shape of the kneading blade.

(2) The tip clearance between the tip of the kneading blade and the inner wall of the kneading tank is 1 mm or more and 3 mm or less.
If the tip clearance is less than 1 mm, it will cause wear of the kneading blade or kneading vessel inner wall due to contact between the tip of the kneading blade and the inner wall of the kneading vessel, or contamination of the metal foreign material into the rubber cloth, and if the tip clearance exceeds 3 mm, Since the amount of the rubber dough passing through the chip clearance increases, the residence time of the rubber dough in the vicinity of the front surface of the kneading blade is shortened, and the kneading action is impaired by reducing the swirling motion of the rubber material and the accompanying amount of extension deformation.

(3) The axial length of the kneading blade is 65% or more and 95% or less of the axial length of the rotor.
When the axial length of the kneading blade is less than 65% of the axial length of the rotor, the residence time of the rubber fabric on the front surface of the kneading blade is short, and the swirling motion of the rubber material and the amount of elongation deformation associated therewith are small. Thus, the kneading action is impaired. On the other hand, when the axial length of the kneading blade exceeds 95% of the axial length of the rotor, the inflow pressure loss of the rubber cloth to the blade end opening increases, and the efficiency of simple mixing decreases, This causes problems such as abnormal wear on the inner wall of the chamber in the direction of the blade shaft end face.

(4) The twist angle of the kneading blade is less than 45 degrees and 5 degrees or more.
When the twisting angle of the kneading blade is 45 degrees or more, the rubber material in the vicinity of the front surface of the kneading blade is accelerated in the axial direction of the kneading blade. The swirling motion of the material and the amount of elongation deformation accompanying it are reduced, and the kneading action is impaired. On the other hand, when the twist angle of the kneading blade is less than 5 degrees, the flow of the rubber material in the vicinity of the front surface of the kneading blade in the axial direction of the kneading blade is impaired, and the efficiency of simple mixing is reduced.
(5) In addition, by increasing the number of kneading blades, it is possible to increase the absolute amount of expansion and deformation accompanying the swirling motion of the rubber material in the vicinity of the front surface in the target kneading blade rotation direction.

  In the present invention, by providing the blade shape of the above configuration, the kneading action of the rubber material, in other words, the formation of the quasi-glass state phase formed around the reinforcing agent compounded in the rubber is greatly promoted, and the kneading time is reduced. Shortening is possible. Therefore, the productivity can be improved in the rubber kneading step as intended by the present invention.

Configuration explanatory diagram of a tangential type sealed rubber kneader according to an embodiment of the present invention A perspective view of a rotor and a stirring blade provided in the tangential sealed rubber kneader Illustration of kneading action of rubber material Illustration of heterogeneous structure of carbon black filled rubber Graph showing the relationship between C phase: quasi-glass state phase volume ratio and rubber hardness Graph showing the effect on kneading speed and the average instantaneous power up to BIT Photograph showing the kneading state of the dough block Explanatory drawing showing the sum of the flow of dough in the blade kneading section Photograph showing the kneading state of the dough block Graph showing quasi-glass phase growth rate of kneading blade

As described above, and as shown in FIGS.
(1) In a tangential sealed rubber kneader 10 that includes a rotor 12 that rotates in a kneading tank 11 and a kneading blade 13 that performs kneading operation on the circumferential surface of the rotor 12, the vicinity of the front surface of the kneading blade 13 in the blade rotation direction We were biting angle theta ₁ an angle of less than 90 degrees than 55 degrees of the kneading blade 13 to promote the expansion deformation caused by the pivoting movement of the mixing materials in,
(2) The tip clearance c between the tip of the kneading blade 13 and the inner wall of the kneading tank 11 is 1 mm or more and 3 mm or less,
(3) to the axial length _{L 1} of the kneading blade 13 has the axial length _{L 2} compared to 95% or less of the length of 65% or more of the rotors 12,
(4), characterized in that the torsion angle theta ₂ to 5 times more than the angle less than 45 degrees of the kneading blade 13. Therefore, the background and consideration that led to the present invention will be described below.

(1) Definition of kneading action and kneading speed The kneading action of the rubber material is made up of “Subdivision”, “Incorporating”, “Dispersion”, “Simple mixing” by H. Palmmgren (Patent Document 2). Although it is said that the process (FIG. 3) such as (Simple Mixing) is performed, it is very difficult to discuss the kneading speed for these plural processes.
On the other hand, as proposed by Fujimoto (Patent Documents 3 and 4) as “non-uniform structure model of carbon black-filled rubber” (FIG. 4), the base material of the rubber material is carbon black and A phase: rubber state phase. , B phase: collective cross-linking molecular phase, C phase: quasi-glass state phase, some processes of the kneading process are conveniently called "C phase: formation of quasi-glass state phase" It is considered that it can be handled as one kneading action.

In order to evaluate the formation of this C phase: quasi-glass state phase as the kneading speed, it is necessary to estimate the volume.
For this reason, based on the following assumptions, from the measured values of rubber hardness of various rubber materials containing various carbon blacks such as HAF, FEF, SRF, thermal grade, etc., for each rubber material, C phase: quasi-glass state The volume ratio of the phases was estimated.
a. Additivity is established between the rubber hardness of the entire rubber base and the hardness and volume ratio of each element constituting the rubber base.
b. Carbon black and C phase: The hardness of the quasi-glass state phase is regarded as 100 points when the rubber hardness is considered, and the hardness of the A phase: rubber state phase and B phase: collective cross-linking molecular phase does not include carbon black. Considered the hardness of rubber.
The result is as shown in FIG. 5, and without being greatly affected by the type and blending amount of carbon black, for each polymer type of the rubber material, between the volume ratio of the C phase: quasi-glass state phase and the rubber hardness. A very good correlation could be obtained.

The volume ratio of this C phase: quasi-glass state phase has a correlation with the tensile strength of the rubber material, the power consumption during rubber kneading, and the kneading time until BIT, in addition to the correlation with rubber hardness. It is thought that the proposed “non-uniform structure model of carbon black-filled rubber” shows the appropriateness as a model of the base material of the rubber material. Based on this, the formation of C phase: quasi-glass state phase Can be defined as a kneading action, and it is possible to define commonality and universal kneading speed, kneading speed is kneading speed = C phase: volume of quasi-glass state phase / BIT (Black Incorporation Time)
And used as an evaluation scale in the following study.

(2) Relationship between polymer properties (inflow pressure loss) and kneading state (kneading power) with respect to kneading rate The kneading rate was defined as the growth rate of the C phase: quasi-glass state phase.
On the other hand, the kneading action is introduced by I. Manas (Patent Documents 5 and 6) as a breaking action of the secondary agglomerates, and the breaking of the agglomerates depends on a parameter Z proportional to the viscosity of the polymer. It is said that the kneading action is brought about by external fluid dynamic force, but if it is assumed, the kneading speed defined above is also observed as instantaneous power during kneading due to polymer viscosity and polymer viscosity. It is considered to have a correlation with external force.
In addition, the source of this external force can include two types of shear viscosity, which is the shear action that the polymer receives, and the extension viscosity, which is the extension action of the polymer. If the contribution can be confirmed, it is possible to clarify the deformation to be imparted to the rubber material to be kneaded, and it is possible to estimate the shape of the kneading blade suitable for kneading.
For this confirmation, a kneading experiment using various EPDM polymers having different elongational viscosities and shear viscosities as the object of evaluation, the relationship between the kneading speed and the power during kneading, the power during kneading, the shear viscosity of the EPDM polymer, An attempt was made to confirm the relationship with the extensional viscosity.
Incidentally, the extensional viscosity was replaced with the inflow pressure loss measured by a capillary viscometer, and the shear viscosity was evaluated as a shear stress by multiplying by a shear rate of 200 (1 / s).
A result is shown to FIG. 6 (A) (B) (C).

FIG. 6 (A) shows that the kneading speed (phase C up to BIT: quasi-glass) increases as the average instantaneous power up to BIT (the value obtained by dividing the cumulative amount of power up to BIT divided by the time (sec) up to BIT). It shows that the growth rate of the state phase) increases, and that the greater the external force applied to the rubber fabric during the kneading process, the faster the kneading rate.
Two sources of external force applied to the rubber fabric during this kneading process are considered: shear stress and inflow pressure loss. FIGS. 6 (B) and 6 (C) show the shear stress, average instantaneous power up to BIT, and inflow. Although the correlation between the pressure loss and the average instantaneous power up to BIT is shown, the correlation between the inflow pressure loss and the average instantaneous power up to BIT shown in FIG. Since it is very good compared with the correlation between the stress and the average instantaneous power up to BIT, it is considered that the inflow pressure loss, in other words, the external force based on the extensional viscosity greatly affects the kneading speed.

(3) Confirmation of kneading action by observing the flow and deformation state of the rubber dough near the kneading blade As described above, it is confirmed that the source of external force that greatly affects the kneading action and kneading speed is elongation viscosity (inflow pressure loss). did.
For this reason, if it is possible to know the deformation state of the rubber dough in the kneading tank of the tangential closed kneading machine, it is considered possible to design a kneading blade shape for enhancing the stretching action of the rubber dough. Although the evaluation implies the expansion and deformation of the rubber dough in the kneading tank, the evaluation does not clearly indicate the state of the expansion or deformation of the rubber dough or the location in the kneading machine.
For this reason, for the purpose of confirming elongation deformation, an attempt was made to confirm the deformation state of the dough in the kneading machine for the color rubber.

9 (A) to 9 (H) show a dough block in which red, green, blue, yellow, white, and black 1cm square doughs are combined as shown in FIG. 7 (A) once in the kneader. FIG. 8 shows an outline of a relative positional relationship with respect to the kneading blade in a cross-sectional photograph of the dough deformed by passing.
In addition, in each dough section, the kneading blade contact surface and the flow direction of the dough near the kneading blade contact surface are indicated by arrows.
These pictures
a. At the front surface of the kneading blade, the kneading blade rotates in the direction opposite to the rotation direction.
b. It is greatly extended near the front of the kneading blade.
c. When the kneading blade in contact changes, the rotation direction of the dough changes, so that a fault due to twisting of the dough as shown by a broken line in FIG. 9 (E) at position j and FIG. 9 (F) at positions k, m, and o. ) (G) (H), the coexistence of two flows in opposite directions can be seen.
Since the dough shown in these photographic diagrams is considered to have moved in the axial direction of the kneading blade, it is considered that the dough is swirling spirally as a whole. It was confirmed that there was a large elongation action.
This stretching action is considered to be a source of external force that promotes the kneading action.

It is considered that several processes of the above-mentioned (1) kneading process can be handled as one kneading action such as “C phase: formation of quasi-glass state phase” for convenience.
(2) Kneading speed = C phase: quasi-glass state phase volume / BIT (Black Incorporation Time)
(3) The higher the average instantaneous power to BIT (in other words, the external force for kneading), the faster the C phase: quasi-glass state phase growth speed (kneading speed), and the higher the polymer inflow pressure loss, the average instantaneous power to BIT. Since the elongation is large, it can be determined that the elongation action of the polymer is the source of the kneading action.
(4) In the kneader, it can be confirmed that there is a large elongation action in the swirl flow in front of the blades and in the reversal of the dough rotation direction between the blades.
Therefore, the kneading blade shape that can be expected to improve the kneading speed in the tangential closed kneading machine is considered to be a shape that can enhance the stretching action of the rubber fabric caused by the swirling motion of the rubber fabric on the front surface of the blade. It is considered that the staying time can be increased.

In particular,
a. A kneading blade having a small opening ratio at the end of the kneading blade (the ratio of the blade length to the axial length of the rotor of the kneading tank is large);
b. A kneading blade with a large penetration angle (Leading Angle, Front Angle),
c. A kneading blade with a small twist angle,
d. A kneading blade such as a kneading blade with a small chip clearance,
It becomes.

(4) Verification of influence of blade shape on kneading speed based on kneading mechanism Based on the above, the kneading speed of various rubber materials was confirmed with the following kneading blade, and the credibility of the hypothesis was confirmed.
a. Test blade shape

b. Test rubber material (a) ACM material: Noxtite PA404K (ML1 + 4 at100 ° C 30 points) 100 parts
ADK Sizer RS700 5 parts, Rheodor SPS10 1 part,
3.5 parts of sodium stearate (NS Soap)
1.2 parts of potassium stearate (non-sar SK-1), 1 part of stearic acid,
Anti-aging agent CD 2 parts, sulfur 0.3 parts (b) Reinforcing agent:
A. Carbon black-show black N330L 80 parts b. Carbon black-Seast G-S0 80 parts c. Wet silica-Nipseal E74P 60 parts2. Wet silica-Nipseal LP 40 parts

c. Kneading machine 5L Wonder 2-der: Moriyama WDS5-75MWA-S type motor output 75 horsepower, seagull type pressure lid,
Actual volume: 5.2L when mounted on a wonder kneader blade
d. Kneading conditions (a) Pressure lid pressure: carbon black material-air pressure 0.6 MPa
Wet silica material-0.3 MPa
(B) Filling rate: 65%
(C) Blade rotation speed: 24 rpm
(D) Kneading method a. The chemicals, plasticizer, and carbon are added together and stirred for 30 seconds, then the polymer is added and pressurization is started.
Note 1: In the case of the ACM carbon black material, since the kneading temperature rises quickly, a small amount of chemical was added immediately before the second step (after the first step and cleaning).
Note 2: The carbon black material was lowered to the lowest level immediately after the introduction of the polymer, but in the case of the silica material, after the introduction of the polymer, the pressure lid was moved to the lowest intermediate stop position after the introduction of the polymer to prevent the silica from scattering. After waiting for 2 seconds, it was lowered to the lowest level.
B. After confirming BIT, knead for about 45 seconds, and after cleaning, knead for about 60 seconds.
C. The summary was taken out at 5 mm after passing 5 times at 12′OR and a roll interval of 3 mm.

e. Results of kneading rate evaluation The evaluation results of the growth rate of the quasi-glass state phase of each kneading blade (= quasi-glass state phase volume (cc) / kneading time up to BIT (sec)) obtained by the above examination are shown in FIG. Shown in
Example 1 (Blade C) is a blade having a narrow tip clearance (chip clearance: 1 mm) among the elements estimated to have a blade shape capable of improving the kneading speed in the previous section. Compared to (clearance: 3 mm), it can be determined that the growth rate of the quasi-glass state phase is faster and the kneading speed is improved in any material (regardless of the type and amount of carbon black). .

  Further, Example 2 (Blade D) was obtained by increasing the biting angle (biting angle: 65 °) among the elements estimated as the blade shape capable of improving the kneading speed in the previous section. Compared to A (bite-in angle: 55 °) and blade B (bite-in angle: 30 °) in Comparative Example 2, in any of the materials (regardless of the type and amount of carbon black), the quasi-glass state phase It can be determined that the growth rate is high and the kneading rate is improved.

  Further, when the growth speeds of the quasi-glass state phases of blade A of comparative example 1 (bite angle: 55 °) and blade B of comparative example 2 (bite angle: 30 °) are compared, the quasiglass of blade A having a large bite angle. The growth rate of the state phase is slightly faster than that of the blade B, and this result also supplements the above conclusion that the kneading speed increases as the biting angle increases.

From the above, “the kneading blade shape that can be expected to improve the kneading speed in the tangential closed kneader is considered to be a shape that can enhance the stretching action of the rubber fabric caused by the swirling motion of the rubber fabric on the front surface of the blade. It can be determined that the hypothesis that it is possible to increase the staying time on the front surface has been verified,
a. A kneading blade having a low opening ratio at the end of the kneading blade (the ratio of the axial length of the blade to the axial length of the kneading tank is large);
b. A kneading blade with a large penetration angle (Leading Angle, Front Angle),
c. A kneading blade with a small twist angle,
d. Kneading blade with small chip clearance,
It can be concluded that the kneading blade shape improves the kneading speed of the tangential closed kneader.

10 Tangential Type Sealed Rubber Kneader 11 Kneading Tank 12 Rotor 13 Kneading Blade θ ₁ Biting Angle θ ₂ Torsion Angle c Chip Clearance L ₁ Axial Length of Kneading Blade L ₂ Axial Length of Rotor

Claims (4)

In a tangential type sealed rubber kneader equipped with a kneading blade that kneads and operates on the peripheral surface of the rotor, with a rotor that rotates in the kneading tank,
A tangential sealed type characterized in that the biting angle of the kneading blade is more than 55 degrees and less than 90 degrees in order to promote the stretching deformation accompanying the swirling motion of the rubber material in the vicinity of the front surface of the kneading blade in the blade rotation direction. Rubber kneader. In the tangential sealed rubber kneader according to claim 1,
A tangential sealed rubber kneader characterized in that the tip clearance between the tip of the kneading blade and the inner wall of the kneading tank is 1 mm or more and 3 mm or less. In the tangential type sealed rubber kneader according to claim 1 or 2,
A tangential sealed rubber kneader characterized in that the axial length of the kneading blade is 65% to 95% of the axial length of the rotor. In the tangential sealed rubber kneader according to claim 1, 2, or 3,
A tangential sealed rubber kneader characterized in that the twisting angle of the kneading blade is less than 45 degrees and 5 degrees or more.