JPH10249827A - Manufacture of carbon black molding and method for degassing powder with high efficiency - Google Patents

Abstract

PROBLEM TO BE SOLVED: To largely improve handleability and to simultaneously provide a sufficient dispersibility by giving vibration to carbon black before pressurizing and/or during pressurizing the black. SOLUTION: An exciter 6 gives vibration to a carbon black powder 8, and may be any means if it is a mechanism for generating the vibration. Its frequency is 10Hz to 100kHz or preferably 500Hz to 20kHz. Its amplitude is effective if it is 3μm (one-side vibrating amplitude) or more, and preferably 6μm or more. And, the exciter 6 may be installed at a sidewall of a die. A cylinder mounting board 7 is a frame for fixing a lower punch 10 and corresponds to a foundation of an overall apparatus. The powder 8 in the die 3 is directly brought into contact with an upper punch 9 and the punch 10, and pressurized. A time for giving the vibration is before or during pressurizing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently degassing carbon black powder at the time of molding, and a method for efficiently molding carbon black powder thereby.

[0002]

2. Description of the Related Art Carbon black is a typical black pigment, and is also used for various purposes such as a reinforcing material in a rubber composition. Carpon black has a small particle size and a low bulk density, and therefore has large environmental problems such as dust generation and contamination. In particular, the furnace black obtained by the furnace method, which accounts for almost the majority of products currently on the market, has various favorable properties, but the above problems due to its small particle size, small structure, and small amount of surface adsorbed substances. And dispersion in the vehicle is also difficult.

In order to solve such a problem, a dry granulated product called a bead product or a wet granulated product (having a bulk density of 0.1%) has been conventionally used.
3 to 0.5 g / cc, which is considerably higher in bulk density than untreated carbon black), but the suppression of dust generation and pulverization of granulated material is not sufficient, and In some cases, the dispersibility of the paint or ink in the vehicle becomes poor, and beads may not be used.

As described above, conventionally, when the bulk density of carbon black is increased to obtain handling properties, that is, ease of handling, dispersibility in a vehicle is impaired. In short, the handling properties and dispersibility of carbon black are contradictory. It was widely recognized that it was extremely difficult to solve these at the same time. If the basic characteristics of carbon black used for various purposes such as paint, ink, resin coloring, rubber reinforcement, etc. are impaired by improving storage / transportation costs, handling, and the environment, it must be satisfactory as a product. And is not accepted by the market. For this reason, various proposals have conventionally been made, but there has been no example in which these two problems were simultaneously solved.

[0005]

As an epoch-making technology which can solve this problem, the present inventors have previously made carbon black into a molded product by pressure molding. (Japanese Patent Application No. 8-251457) has developed a carbon black molded body which has greatly improved handling properties and sufficient dispersibility.

The inventors of the present invention have found that the following problems should be further solved when industrially producing a carbon black molded article having such novel and revolutionary excellent properties. That is, the carbon black powder has a low bulk density and is very difficult to deaerate. For this reason, at the time of press molding, if the degassing is insufficient, the resulting molded article may have layer cracks.

It is difficult to keep the bulk density of carbon black powder constant, and even if the bulk density is increased by vacuum degassing or the like, it tends to return to the original in the next step. Therefore, when the carbon black powder is charged into the mold, a distribution occurs in the bulk density inside the mold. In particular, for brands having no fluidity, density distribution, that is, density unevenness is likely to occur in the obtained molded product. The dispersibility tends to decrease as the bulk density increases, and eliminating the density distribution in one molded body improves the dispersibility of the carbon black molded body in the vehicle.

[0008]

Means for Solving the Problems In order to solve the above problems,
The present inventors have further studied diligently. As a result, by applying vibration at a specific time during carbon black pressure molding, efficient and timely deaeration can be performed, the density unevenness of the obtained molded body can be suppressed, and dispersibility in the vehicle can be suppressed. At the same time, it was found that the occurrence of layered cracks, cracks, etc. of the molded product could be prevented, and the present invention was reached. That is, the present invention provides a method for producing a carbon black molded body by placing carbon black in a mold and pressurizing, and applying vibration to the carbon black before and / or during the pressurization of the carbon black. The present invention relates to a method for producing a black molded body.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
According to the present invention, a molded article having a certain shape is obtained by putting carbon black into a mold and applying pressure.
FIG. 1 shows an outline of the pressurizing operation of the present invention.

In the figure, reference numeral 1 denotes an upper cylinder, which is a drive source for moving the upper punch (9) up and down via a cylinder rod (2). The upper punch (9) can be moved up and down,
Any material can be used as long as it can pressurize the carbon black powder at a desired pressure. For example, there are hydraulic and pneumatic cylinders. 2 is a cylinder rod. This is for connecting the upper cylinder (1) and the upper punch (9).

Reference numeral 3 denotes a die. It constitutes the side wall of the room for charging the carbon black powder. 4
Is a cylinder rod. This is for connecting the lower cylinder (5) and the lower punch (10). 5 is a lower cylinder. It is a drive source for moving the lower punch (10) up and down via the cylinder rod (4). Any material can be used as long as it can move the lower punch (10) up and down and press the carbon black powder at a desired pressure. For example, there are hydraulic and pneumatic cylinders.

Reference numeral 6 denotes a vibrating unit for applying vibration to the carbon black powder. The vibrating unit may be a method of applying a voltage to the piezoelectric ceramic to apply vibration, or a method of applying vibration according to the number of switching of the hydraulic valve per unit time. Any method can be adopted as long as it generates vibration. Frequency is 10Hz-100K
Hz, preferably 500 Hz to 20 kHz. If the amplitude is 3 μm (amplitude of single vibration) or more, there is an effect. Preferably, it is 6 μ or more.

Further, the vibrating section may be installed on the side wall of the die. 7 is a cylinder mounting board. Lower punch (1
A frame for fixing 0), which corresponds to a basic portion of the entire apparatus. 8 is carbon black. The carbon black powder to be charged may be of any brand, the form is not particularly limited, and it does not matter whether it is a powder (so-called loose product) or a granulated product (so-called bead product). Of course, it may be a flake-like product formed by a roller compactor. Of course, various oxidation products and special grade products can also be used.

Reference numeral 9 denotes an upper punch. This is for directly contacting the carbon powder inside the die and applying pressure from above.
10 is a lower punch. For direct contact with the carbon powder inside the die and pressurization from below. The present invention is characterized in that during the pressurizing operation of carbon black, vibration is applied to the carbon black before and / or during pressurization. The vibration is applied before or during pressurization. In the case of degassing by applying vibration before pressurization, if the gas between the carbon black particles is degassed by the vibration and the carbon black powder surface falls to a desired degree, the pressurizing operation can be started. For example, before pressing, the upper punch is lowered and when the upper punch contacts the carbon black powder, the upper punch is stopped and vibration is applied. After degassing in this manner, the upper punch may be further lowered and molded under pressure. Of course, vibration may be applied before pressurization, and vibration may be applied during pressurization.

The degree of deaeration can be confirmed to a desired degree by measuring the rise in bulk density when deaeration is performed by applying vibration before pressurization. When degassing by applying vibration during pressurization, for example, molding a carbon black powder that is difficult to mold, the resulting molded body does not crack, etc., and whether or not the desired degassing effect is exhibited Can be confirmed.

The pressure during molding under pressure (molding pressure) is 2-5.
It is good to be 00 kgf / cm ² , more preferably 5 to 400 kgf / cm ² . When the molding pressure is less than ² kgf / cm ² , the compact of the obtained molded body tends to decrease, and the powdering ratio tends to increase (pulverization becomes easy). On the other hand, the molding pressure is 500kg
If it is higher than f / cm ^2, a dispersing machine used in the production of ordinary inks and paints may not have sufficient dispersibility. On the other hand, even if the pressure is further increased, the effect of improving compactness can hardly be obtained. For this reason, ink,
Paints, colored resins, carbon black moldings used when industrially producing rubber, etc., are 2 to 500 kgf / cm
It is appropriate to perform pressure molding in ² .

The press used for pressurization includes a hydraulic mechanical press, a hydraulic hand press, a mechanical press,
Any material can be used without particular limitation as long as it can press-mold the powder, such as an air cylinder press. The density of the carbon black molded body produced by pressurization is not particularly limited, but preferably, the density of the obtained molded body is desirably within the following range.

That is, the density ρ (g / cc) is

[0019]

[Formula 1] ρ = 8.190 × 10 ⁻³ D3.824 × 10 ⁻³
L + 0.516 or more, ρ = 3.265 × 10 ⁻³ D−3.334 × 10 ⁻³ L +
1.173 or less. More preferably,

[0020]

[Formula 2] ρ = 8.686 × 10 ⁻³ D−4.031 × 10
⁻³ L + 0.543 or more, ρ = 3.123 × 10 ⁻³ D−3.189 × 10 ⁻³ L +
1.072 or less is preferable. In addition, the density of the molded body is a value obtained by dividing the mass of the molded body by the volume.

In each of the above equations, D (nm) is the arithmetic average particle diameter of carbon black measured by an electron microscope, and L (m
1/100 g) is the DBP oil absorption. Here, the DBP oil absorption is a value measured by a method based on JIS K6221-1982. The particle size of the carbon black is a value measured by the method described below.
Put carbon black into chloroform and add 200KHz
Is dispersed for 20 minutes, and the dispersion sample is fixed to a support film. This is photographed with a transmission electron microscope, and the particle diameter is calculated based on the diameter on the photograph and the magnification of the photograph. This operation is performed about 1500 times, and the values are obtained by arithmetic averaging.

By setting the density within the above range, it is possible to make the carbon black particularly excellent in handleability without impairing basic characteristics of the carbon black such as dispersibility in a vehicle. Further, it has an unexpected effect that the jetness when used in inks, paints and the like can be improved as compared with the raw material powder. These effects are particularly remarkably exhibited in the range described as the more preferable range described above.

The carbon black molded article of the present invention preferably has a powdering ratio of 40% or less, more preferably 20% or less. The powdering rate was determined by precisely weighing a carbon black press-molded body to 25 ± 1 g (W),
200mm in diameter and 1m in mesh according to K-6221
m. Attach a saucer and lid to this sieve,
Shake while giving a blow for 20 seconds with a shaker conforming to SK-6221. Remove the pan from the shaker, the weight of the carbon black in the pan was 0.01g Madeseihakari, and the weight (W _R) after shaking it, is a value obtained by the following equation.

[0024]

[Equation 3] powdering rate (%) = a (W _R / W) × 100 powdering rate by 40% or less, it is possible to prevent powdering due to an external force of vibration or friction applied to the molded body during transport In particular, the handleability is particularly excellent. Further, the ratio between the bulk density of the powdery carbon black as a raw material and the density of the carbon black molded body (hereinafter also referred to as “bulk density ratio”) is 2.5 to 8 times, more preferably 3 to 7 times. Good to do. If the bulk density ratio is lower than 2.5, the compactness of the molded body tends to decrease. On the other hand, when the bulk density ratio is 8
If it exceeds, the dispersibility tends to decrease. When the bulk density ratio is 2.5 to 8, compactness and dispersibility are simultaneously satisfied in an extremely preferable range.

Hereinafter, the present invention will be described more specifically with reference to examples. Examples 1 and 2 A pressurizing device (YPC manufactured by Yuken Kogyo Co., Ltd., “YPC
F-20-AP ") using a Mitsubishi Chemical Corp. carbon black powder" MA8 "(bulk density 0.166 g / cc, DPB oil absorption 68cc / 100g, a specific surface area of 137m ² / g) to 150mm Kakukin type I charged. The carbon black powder was pressure-molded with the upper cylinder at 3 mm / sec while giving a vibration having a frequency of 400 Hz and an amplitude of 250 μm by the vibrating section (6).
The pressures at the time of molding were set to 20 kg / cm ² and 85 kg / cm ² , respectively, as Examples 1 and 2. The density of a portion 10 mm from the surface of the obtained carbon black pressure molded body was measured for the portions A, B, and C shown in FIG. The results are shown in Table 1. FIG. 2 is a plan view of the molded body. Comparative Examples 1 and 2 Except that vibration was not applied during pressurization, a carbon black molded body was produced by the same operation as in Examples 1 and 2, and the same measurement as in Example 1 was performed. The results are shown in Table 1.

[0026]

[Table 1] * 1: Crack generation, measurement not possible. * 2: In the molded body obtained by molding without applying vibration, several cracks occurred on the side surface of the molded body.

[0027]

According to the present invention, carbon black powder can be efficiently degassed during carbon black pressure molding, and the occurrence of cracks in the obtained carbon black molded body can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a pressurizing operation of the present invention.

FIG. 2 is a diagram showing locations where the density of a molded body is measured in Examples and Comparative Examples.

[Explanation of symbols]

 1 upper cylinder 3 die 5 lower cylinder

Claims (3)

[Claims] 1. A carbon black, wherein a carbon black is placed in a mold and pressurized to produce a carbon black molded body, wherein the carbon black is subjected to vibration before and / or during the pressurization of the carbon black. Manufacturing method of molded body. 2. A method of producing a carbon black molded body by placing carbon black in a mold and applying pressure, wherein vibration is applied to the carbon black powder before and / or during the application of carbon black. How to degas carbon black powder. 3. The method according to claim 1, wherein the vibration applied to the carbon black is a vibration having a frequency of 10 Hz to 100 KHz.