JPH09294904A - Diaphragm in filter press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the diaphragm in a compression type filter press which is made from a thermoplastic elastomer having good oil resistance and mechanical properties. SOLUTION: A diaphragm is made from a mixture of polyolefin I, acrylonitrile-butadiene copolymer rubber II, and olefin copolymer rubber III incorporated optionally or the partially crosslinked product of the mixture. In the polyolefin thermoplastic elastomer which constitutes the diaphragm, the weight ratios of the rubber II and the rubber III to the resin I are (50:50)-(70:30).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm in a compression type filter press, and more particularly to a diaphragm having excellent oil resistance.

[0002]

2. Description of the Related Art In recent years, there has been a demand for high dehydration in the field of filtration in order to save energy, and squeeze-type filter presses have been widely used. This squeeze type filter press is provided with a core plate and a diaphragm on one side of a filtration chamber, and is configured to further squeeze the cake press-filtered by a pump. The diaphragm used here has excellent heat resistance. , Heat aging resistance, chemical resistance, oil resistance, durability,
Furthermore, characteristics such as mechanical strength are required. Generally, as the material of the diaphragm, natural rubber (NR), styrene rubber (SBR), nitrile rubber (NBR), ethylene-propylene rubber (EPR) is used depending on the content of the object to be filtered, for example, the type and temperature of the slurry.
Synthetic rubber such as is commonly used. However,
Such a natural rubber or a synthetic rubber has poor heat resistance, heat aging resistance, chemical resistance, and the like.

In order to improve these properties, the applicant previously reported that a polyolefin resin and an ethylene-propylene copolymer rubber (hereinafter referred to as EPM) or an ethylene-propylene-non-conjugated diene copolymer rubber (hereinafter referred to as EPM). , E
PDM) in a weight ratio of 10:90 to 50:50.
It has been proposed that the diaphragm be composed of a thermoplastic elastomer which is mixed and mechanically blended within the range described above or partially cross-linked (Japanese Patent Publication No. 3-50562). But,
If this diaphragm is used for a long time for squeezing and filtering a slurry containing various oils, it swells due to the oil, causing a change in weight (volume) and a decrease in mechanical strength. There is also a possibility that it may lead to leakage or damage to the diaphragm.

[0004]

SUMMARY OF THE INVENTION The present invention provides a diaphragm in a squeeze filter press made of a thermoplastic elastomer that does not have the above drawbacks and has excellent oil resistance and mechanical properties. .

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a diaphragm made of an elastomer excellent in oil resistance and mechanical properties in addition to the conventional properties such as heat resistance and chemical resistance. Is a polyolefin resin (I)
And acrylonitrile-butadiene copolymer rubber (II), and the weight ratio of the rubber (II) to the resin (I) is 50:50 to 70:30. The second gist of the acrylonitrile-butadiene copolymer rubber (II) mixed with the polyolefin resin (I) is a mixture of the rubber (II) and the olefin copolymer rubber (III), or This rubber mixture is a partially crosslinked product obtained by partially crosslinking it with a crosslinking agent, and
I) and rubber (III) are present in the diaphragm in the filter press, which is formed by mixing 99: 1 to 30:70 (weight ratio). A further gist is a mixture containing a polyolefin resin (I), an acrylonitrile-butadiene copolymer rubber (II) and an olefin copolymer rubber (III), or a partially crosslinked product of the mixture, and the resin in the mixture. The total weight ratio of the rubbers (II) and (III) to (I) is 50:50 to 70:30, and the weight ratio of the rubber (II) to the rubber (III) is 99: 1 to.
A diaphragm in a filter press made of a thermoplastic thermoplastic elastomer of 30:70.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The polyolefin-based thermoplastic elastomer forming the diaphragm in the filter press of the present invention is basically composed of hard segments and soft segments. The polyolefin resin (I) used as the hard segment is a homopolymer or copolymer of α-olefin such as ethylene and propylene, and examples thereof include polyethylene, isotactic polypropylene, syndiotactic polypropylene and propylene-ethylene copolymer. Examples thereof include polymers, propylene-1-hexene copolymers, and propylene-methyl-1-pentene copolymers.

In the elastomer of the present invention, the polyolefin resin which is the hard segment must be contained in an amount of 50 to 70% by weight. If it is less than 50% by weight, the swelling resistance when immersed in oil is poor, in other words, the weight change is large. Therefore, when mechanical strength, which is an important characteristic of the diaphragm, particularly tensile strength and hardness, is reduced and the diaphragm is damaged, or there is a risk of leakage of slurry due to deterioration of the sealing property between the diaphragm and the core plate. There is also. On the other hand, if it exceeds 70% by weight, the elongation at break is lowered, and the hardness is increased to lower the sealing property, so that the function as a diaphragm may not be sufficiently exhibited.

The acrylonitrile-butadiene copolymer rubber (II) used as the soft segment has an acrylonitrile content of 10 to 90% by weight, preferably 15 to 5%.
It is preferable to use one that is 0% by weight. If the acrylonitrile content in this NBR is less than 10% by weight, sufficient oil resistance cannot be exhibited, and the performance of the diaphragm used in the slurry containing oil is inferior. The acrylonitrile-butadiene copolymer rubber (II) used is the above-mentioned acrylonitrile-butadiene copolymer 2
In addition to the component copolymers, terpolymers such as acrylonitrile-butadiene-trifluoroethyl acrylate and acrylonitrile-butadiene-acrylic acid ester, and hydrogenated acrylonitrile-butadiene copolymer rubber (II) can be used. As the acrylonitrile-butadiene copolymer rubber (II), an acrylonitrile-butadiene copolymer rubber (II) component-containing composition containing various additives such as an anti-aging agent which is usually commercially available is also used in the present invention. can do.

As another embodiment of the present invention, a mixture of acrylonitrile-butadiene copolymer rubber (II) and olefin copolymer rubber (III) can be used as the soft segment. In that case, the acrylonitrile-butadiene copolymer rubber (II) and the olefin copolymer rubber (II
The ratio with I) is selected from the range of 99:30 to 1:70 by weight. If this ratio is 30/70 or less,
It is not preferable because the effect of improving oil resistance is not sufficient and the performance of the diaphragm used in the slurry containing oil is inferior. In the present invention, by using the acrylonitrile-butadiene copolymer rubber (II) and the olefin copolymer rubber (III) together within the above range, the effects exhibited by both components are synergistically exhibited, and in addition to the oil resistance, the mechanical properties are improved. It is possible to obtain a product having excellent physical characteristics. The acrylonitrile-butadiene copolymer rubber (II) as the soft segment and the olefin copolymer rubber (III) are combined in an amount of 50 to 30 relative to 50 to 70% by weight of the olefin resin (I) in the thermoplastic elastomer of the present invention. Used by weight percent. Further, the acrylonitrile-butadiene copolymer rubber (II) and the olefin copolymer rubber (III) can be mixed with the olefin resin as a mixture, but in some cases, this mixture is partially crosslinked with a crosslinking agent and mixed as a partially crosslinked product. You can also do it.

Examples of the olefin copolymer rubber (III) used in the present invention include ethylene-propylene copolymer rubber (EPM) and ethylene-propylene-non-conjugated diene copolymer rubber (EPDM). The EPM has a weight ratio of ethylene and propylene of 20: 80-9.
The ratio is 0:10, preferably 40:60 to 85:15. The proportion of non-conjugated diene in the case of EPDM is
It is 1 to 20% by weight, preferably 4 to 10% by weight. Examples of non-conjugated dienes include chain dienes such as 1,4-hexadiene, 1,4-pentadiene and 1,5-hexadiene, and cyclic polyenes such as dicyclopentadiene, methylene norbornene and cyclooctadiene. In the present invention, as the olefin copolymer rubber (III), a composition containing various additives such as a processing aid such as a plasticizer and a spreading oil in addition to the olefin copolymer rubber component can also be used.

The blending of each component of the thermoplastic elastomer in the present invention is not particularly limited as long as the components to be mixed are sufficiently homogeneously mixed.
Usually, it is performed by mechanically mixing with a Banbury mixer, a single-screw or twin-screw extruder, various types of kneaders or open rolls. The thermoplastic elastomer of the present invention can also be prepared through the following steps of partially crosslinking the soft segment or the mixture of the hard segment and the soft segment with a crosslinking agent. (1) Method of partially crosslinking the soft segment component and blending with the polyolefin resin (2) Method of crosslinking while mixing the soft segment component and the polyolefin resin (3) Kneading the soft segment component and the polyolefin resin in advance Then, the method of crosslinking may be used. The cross-linking reaction is carried out according to a conventional method, such as an organic peroxide which is usually used, such as dicumyl peroxide,
It is carried out using di-t-butyl peroxide, α, α′-bis (t-butylperoxy) p-diisopropylbenzene or the like.

As the mechanical strength (physical properties) of the thermoplastic polyolefin-based elastomer of the present invention, one having a breaking elongation at 23 ° C. of 300% or more is preferable. 30
If it is less than 0%, the large deformation of the diaphragm that occurs during compression cannot be coped with, and the number of times of destruction tends to increase. On the other hand, the hardness of Shore-D is preferably 20 to 55 °. If it is 20 ° or less, it is too soft and the sealing property between the core plate and the diaphragm is inferior, and if it is 55 ° or more, the compression set due to the tightening force (usually 4 to 6 MPa) of the filter press becomes large. It is preferably not more than °.

Molding of the diaphragm with the thermoplastic polyolefin-based elastomer of the present invention as described above can be carried out into a predetermined shape by a generally known injection molding method, compression molding method or the like. Since the diaphragm according to the present invention is formed of the thermoplastic elastomer composed of the above components, it has excellent oil resistance and mechanical properties as compared with the conventional one, and also has heat resistance, It also has good heat aging resistance and chemical resistance, and is extremely useful as a diaphragm for a compression type filter press.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

Examples 1 to 4 and Comparative Examples 1 to 4 Polyolefin resin (PP) and acrylonitrile-butadiene copolymer rubber (II) were added to a pressure type kneader preheated to 180 ° C. according to the compounding recipe shown in Table 1. (NB
R) and / or olefin copolymer rubber (EPDM), and continue kneading until the polyolefin resin melts, and after the polyolefin resin, NBR and / or olefin copolymer rubber (EPDM) are uniformly melt mixed,
Organic peroxide (α, α'-bis (t-butylperoxy) p-diisopropylbenzene) was added and partially crosslinked to obtain a thermoplastic elastomer. The obtained thermoplastic elastomer was compression-molded into a sheet shape, and a plate-shaped test piece was prepared to evaluate the physical properties. Table 1 shows the physical property values and evaluation results of the samples of Examples and Comparative Examples.

Examples 1 and 3 are two-component systems of polyolefin resin and NBR, and Examples 2 and 4 are three-component system of polyolefin resin and NBR and olefin copolymer rubber. On the other hand, Comparative Example 1
It is a two-component system of NBR-free polyolefin resin and olefin copolymer rubber, and Comparative Example 2 is a three-component system, but the ratio of NBR content in the soft segment (rubber component) is less than the specified amount. Comparative Example 3
Is a component containing a polyolefin resin and NBR with a small NBR content, and Comparative Example 4 is a component with a small proportion of the polyolefin resin content in the hard segment.

As is clear from Table 1, the samples of Comparative Examples 3 and 4 do not satisfy both the physical properties required for the diaphragm, that is, hardness and elongation at break. The other samples satisfy these physical properties, but the samples of Comparative Examples 1 and 2 are obviously inferior in oil resistance to the samples of Examples 1 to 4. The difference is A
Notable with STM # 3 oil.

[0018]

[Table 1]

Example 5 Diaphragms were formed by using the samples of Examples 1 to 4 and Comparative Examples 1 to 4, respectively.
3 oil) was immersed at 125 ° C. for 70 hours, and changes in physical properties such as the rate of change in hardness and the retention rate of tensile strength (heat aging in oil) were measured. Table 2 shows the results. As is clear from Table 2, since the diaphragm of the present invention is stable with respect to hot oil with little change in hardness and other properties, it can withstand filtration operation in oil at high temperature and for a long time, and can be used as a conventional polyolefin elastomer. It is clear that it has a remarkable effect on oil resistance as compared with the above.

[0020]

[Table 2]

[0021]

The diaphragm formed of the thermoplastic polyolefin elastomer obtained by mixing the polyolefin resin of the present invention with a specific amount of acrylonitrile-butadiene copolymer rubber, optionally together with the olefin copolymer rubber, is a conventional polyolefin. In addition to the properties such as heat resistance and chemical resistance possessed by the system elastomer, it is excellent in oil resistance and mechanical properties, making it possible to carry out filtration operation of slurry containing oil at high temperature for a long time It is a big advantage for me.

Claims (3)

[Claims] 1. A polyolefin resin (I) and an acrylonitrile-butadiene copolymer rubber (II) are contained, and the weight ratio of the rubber (II) to the resin (I) is 50:
A diaphragm in a filter press, comprising a thermoplastic polyolefin-based elastomer of 50 to 70:30. 2. An acrylonitrile-butadiene copolymer rubber (II) is obtained by combining the rubber (II) with an olefin copolymer rubber (II).
I) or a partially crosslinked product obtained by partially crosslinking this rubber mixture with a crosslinking agent, and the rubber (II) and the rubber (III) are mixed in a weight ratio of 99: 1 to 30:70. The diaphragm in the filter press according to claim 1, wherein 3. A mixture containing a polyolefin resin (I), an acrylonitrile-butadiene copolymer rubber (II) and an olefin copolymer rubber (III), or a partially crosslinked product of the mixture, and the resin in the mixture. The total weight ratio of the rubbers (II) and (III) to (I) is 50:50 to 70:30, and the weight ratio of the rubber (II) to the rubber (III) is 99: 1 to 30: A diaphragm in a filter press, which is composed of a thermoplastic thermoplastic elastomer of 70.