JPS60137645A - Heat-resistant conveyor belt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant conveyor belt, and more specifically to a heat-resistant conveyor belt containing ethylene-propylene co-ψ composite rubber, a specific diorganopolysiloxane, white carbon with a specific surface area of 50 m/g or more, and maleimide in one molecule. The present invention relates to a conveyor belt that has excellent properties such as heat resistance, and has a rubber composition containing an organic compound having two or more groups and a curing agent disposed on the surface layer. .

Conventionally, the surface layer, or cover rubber, of conveyor belts has been made of ethylene-propylene copolymer rubber such as ethylene-propylene copolymer (EPM) and ethylene-propylene terpolymer (EPT, EPDM), or butyl rubber (
FIR), halogenated butyl rubber, etc. are used alone or in combination, and in addition to these rubber components, reinforcing properties,
Carbon black and white carbon 1. to improve various properties such as aging resistance. Various compounding agents such as anti-aging agents were added. However, in the rubber compounding of conventional cover rubbers, due to the chemical structure of the raw rubber and the necessity of carbon black and white carbon as reinforcing agents, the following technical issues arise:
There is a problem.

■ Based on the chemical structure of the raw rubber, the belt surface temperature can be adjusted to 150~150°C.
The lifespan is only about 3 to 6 months when the temperature is 180°C.

■ When carbon black is added as a reinforcing agent, the hue is limited to black and there is no other selectivity; when white carbon is used as a reinforcing agent, the hue can be freely selected depending on the pigment, such as white. , extremely poor wear resistance.

■Electrical properties of cover rubber containing carbon black in consideration of wear resistance, e.g. volume resistivity of 10 to 10 Ω
−υ.

The reality is that a conveyor belt that solves all of these technical problems has not yet been obtained.

The present invention has been made to solve these problems, and an object of the present invention is to provide a conveyor held that has excellent properties such as heat resistance, aging resistance, and electrical properties, and can also be arbitrarily selected in color tone.

In accordance with the above purpose, the present inventors have conducted extensive studies, and as a result, the EPT
And/or using EPM, add a specific diorganopolysiloxane and white carbon to the masterbatch and knead it, add an organic compound having two or more maleimide groups in one molecule and a curing agent, and if necessary. The present invention was accomplished by discovering that a conveyor belt obtained by disposing a rubber composition containing polybutene on the surface layer of a conveyor belt and integrating it with a core portion under heating and pressure satisfies the above object.

That is, the present invention provides: (I) (A) ethylene pavlovylene copolymer and/or
or an eprene-propylene copolymer rubber consisting of an ethylene-propylene terpolymer with 40 to 99% by weight; Kisan 6
100 parts by weight of a mixture consisting of 0 to 1% by weight, (If) 10 to 150 parts by weight of white carbon with a specific surface area of 5 (LD10 or more), (■) 0 parts of an organic compound having at least two maleimide groups in one molecule. This is a heat-resistant conveyor belt, characterized in that a rubber composition containing:

The mixture as component (I) used in the present invention consists of an ethylene-propylene copolymer rubber and a specific diorganopolysiloxane. Propylene copolymer (EPR) and/or ethylene copolymer
Propylene tar, polymer (EPT) is used. The preferred content ratio in the ethylene-propylene copolymer rubber is EPT 50 to 100% by weight, EPMO to 50% by weight.
It is. These ethylene/propylene copolymer rubbers usually have a propylene content in the range of 10 to 70 mol%, but the actual commercially available products often have a propylene content of 15 to 50 mol%, and the molecular weight is 1 to 2× The mechanical strength of this material increases as the content of the ethylene component increases. In addition, as the third component of EPT, dicyclopentadiene, ethylidenenorbornene, 1.4
- Dienes such as hexadiene are copolymerized.

In addition, 1. The diorganopolysiloxane constituting the Toki (T) component has at least one, preferably two or more, alkenyl groups such as vinyl groups and allyl groups and/or mercapto groups in one molecule, and Degree of polymerization is 10001, E
is required. If the degree of polymerization of this diorganopolysiloxane is less than too much, the Mooney viscosity of the compounded rubber will decrease, and bubbles will be generated inside the molded product during vulcanization.

The bonding position of the alkenyl group or mercapto group may be within the molecular chain, at the end of the molecular chain, or both, and it does not necessarily have to be directly bonded to the silicon atom; May be bonded to an atom.

Regarding organic groups bonded to silicon atoms other than alkenyl groups or mercapto groups in this diorganopolysiloxane, all of them are methyl groups, or methyl groups and phenyl groups are often used, and the organic groups are methyl groups. In the case of phenyl groups, it is desirable that the proportion of methyl groups (relative to all organic groups) is 10 mol% or more.

Such diorganopolysiloxane can be produced by a conventionally known method, for example, by hydrolyzing the corresponding diorganodichlorosilane, removing the hydrochloric acid generated therein, and then polymerizing it using an acid or alkali catalyst. Most commonly, cyclic siloxanes of the following formula are obtained: Examples include a method of ring-opening polymerization in the presence of an acid or alkali catalyst. In this case, the alkenyl group or mercapto group is
For example, they can be introduced by mixing and copolymerizing a cyclic siloxane containing them before polymerization. Furthermore, a phenyl group can also be introduced in the same manner as above.

The mixing ratio of the ethylene-propylene copolymer rubber and diorganopolysiloxane constituting component (I) is as follows:
Ethylene-propylene copolymer rubber 40-99% by weight
1% to 60% to 1% di-A arganoborisiloxane
If the proportion of diorganopolysiloxane exceeds 60 ω%, the mechanical strength of the resulting molded product will drop significantly, making it difficult to put it into practical use.

Table 1 of the conveyor belt of the present invention! The rubber composition disposed as the (cover rubber) contains white carbon as the component (II). As the white carbon, it is possible to use common white carbon that has been conventionally blended into silicone rubber and the like.

In the present invention, the white carbon is required to have a specific surface area of 501 d/g or more as measured by the BET method, and more preferably 100 to 300 w110 is used. In the formulation of the present invention, even if white carbon is used alone, its reinforcing effect reaches a sufficient level as a cover rubber (including wear resistance). Furthermore, in the present invention, it is possible to freely select the blending ratio of white carbon/carbon black, thereby making it possible to freely set the electrical properties, especially the volume resistivity, over a wide range of 10 to 10 Ω-Cm. It is. Even if white carbon is used alone in the formulation of the present invention,
Its reinforcing effect reaches a sufficient level as a belt cover material. Furthermore, in the present invention, it is possible to freely select the blending ratio of white carbon/carbon black, which particularly allows the volume resistivity to be reduced from 10 to 10 Ω-
It has the effect of being able to be freely selected from a wide width of cm.

This (If) component white carbon is the above (I
) 100 ingredients! 10 to 150 parts by weight of the wound, preferably 30 to 80 m! It is necessary to blend within the range of ω.

The rubber composition used as the cover rubber contains as component (1) an organic compound having at least two maleimide groups in one molecule. This maleimide group-containing organic compound is also known as a crosslinking agent for ethylene-propylene copolymer rubber, and has the effect of improving the modulus and compression set of the resulting cured product.

The maleimide group-containing organic compound which is the (In) component is 0.5 to 10 parts per 100 small fi parts of the above (T) component.
It is blended within the range of parts by weight.

As the curing agent which is component (IV') of the rubber composition used in the present invention, sulfur, sulfur compounds, organic peroxides, etc. can be used. Specific examples of curing agents such as organic peroxides include benzoyl peroxide, 2.4
-dichlorobenzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethylbis(2,5-di-tert-butylperoxy)hexane, di-tert
t-butyl peroxide, t'ert-butyl perbenzoate, zinc dibutyl dithiocarbame-1, dibenzothiazyl resulfide, 2-mercaptobenzodeazole, tetramethylthiuram monosulfide, tetraedylthiuram disulfide, di Examples include pentamethylene lentithuram tetrasulfide, 2-mercaptobenzimidazole, and zinc dimethylthiocarbamate.

These curing agents are blended singly or in combination, and the blending amount is determined from the above (I) from the viewpoint of curing the rubber composition well.
It is desirable to use it in a range of 0.1 to 10 parts by weight per 100 parts by weight of the component.

It is preferable to blend polybutene into the rubber composition used in the present invention. Although the blending of polysten contributes to improving the processability and peeling force of the rubber composition, excessive blending is not preferable because it causes a decrease in abrasion resistance. Therefore, the preferred blending amount of polybutene is 10% of the above component (I).
It is 1 to 9 parts by weight per 0 parts by weight.

The method for producing the rubber composition used in the present invention is arbitrary, but for example, each component (I) to (III) may be mixed in a Banbury mixer, kneader, inch mixer, etc., which are generally used for rubber. It is prepared by kneading to form a masterbatch using a mixer such as this roll, and then mixing a predetermined amount of component (IV) and other compounding agents such as polybutene to this masterbatch.

The rubber composition thus obtained is placed on the surface layer of a conveyor belt, and is integrated with the core material under heat and pressure to form a conveyor belt.

In addition to the above compounding agents, the rubber composition used for the surface layer in the present invention may optionally contain metal oxides such as titanium oxide, aluminum oxide, zinc oxide, and iron oxide, carbon black, graphite, and calcium carbonate. , mica powder,
Fillers such as clay, talc, quartz powder, celite, baryta, and aluminum hydroxide, flame retardants, process oils, higher fatty acids such as stearic acid and lauric acid, various carbon funk silanes, and various face a, etc. They may be blended as appropriate.

Hereinafter, the present invention will be specifically explained based on Examples and Comparative Examples. In addition, Table 1, Table 2, Table 3, and 15
The formulation numbers in the table are parts by weight.

Examples 1 to 3 and Comparative Example 5 Rubber compositions were prepared by kneading the rubber materials and various compounding agents shown in Table 1. In addition, this cross-wire method t, t E1 Rubber Association 19 q! I rating S RT S 3602-1
This was conducted in accordance with Law 972B. The formulations of masterbatch A and masterbatch B in Table 1 are as shown in Table 2.

The rubber composition thus prepared was heated and pressure treated at 170° C. for 30 minutes, and the obtained rubber composition was obtained. ! The physical properties, crack growth rate, hue, and volume resistivity of i (crosslinked) rubber are determined by JIS.
Measured according to K 6301, and the results are shown in Table 1. The crack growth rate was measured at a stroke of 5 hm1 at room temperature, and the crack growth rate at heating was measured at a stroke of 57 cm in a constant temperature bath at 120°C.

Further, the physical properties of this vulcanized rubber after heat aging at 180° C. for 72 hours were measured in the same manner, and the results are shown in Table 1.

Table 2 As shown in Table 1, masterbatches A and B containing FPM or EPT, a specific diorganopolysiloxane, and white carbon within the scope of the present invention were treated with organic pern11 compound and polybutene as curing agents. The compounded rubber compositions of Examples 1 to 5 were EPDM, EPM, I
Compared to Comparative Examples 1 to 3 in which IR is used as a rubber component and compounding agents such as carbon black are blended with it, the tensile product, tear, force (at room temperature and heat) and crack growth rate before and after aging are extremely good. This shows that it is an elastic material suitable for products that require heat resistance. In particular, Example 3 in which the ethylene-propylene copolymer rubber was blended at a ratio of 50 to 100% by weight of EPT and 50 to 50% by weight of EPMO.
~5 is optimal as each physical property is balanced.

Examples 16 to 10 and ☆Examples 4 to 6 As the core layer, 4 sheets of fiber 1 fabric/coated rubber composition (coated canvas) with a thickness of 1.2 m+++ are stacked, and the upper surface layer is 5IIII11 and the lower surface layer is 21I.
No. 11 was laminated and molded using the rubber compositions of Comparative Examples 1 to 3 and Examples 1 to 5 shown in Table 1. The formulation of the coating rubber composition used for the core layer is shown in Table 3.

Table 3 This molded body was crosslinked, bonded and integrated under heating conditions of 170° C. for 30 minutes to create a 265 m test belt. Regarding this test belt, the top surface layer of the belt was heated to 200°C by infrared irradiation, and changes in the surface layer (before cracking occurred) and wear reduction were measured using a rotating drum running test machine equipped with an etch cock type abrader. 1i11' results are shown in table m4.

As shown in Table 4, the test belts of Examples 6 to 10, in which the rubber compositions of Examples 1 to 5 were used as front layer belts, were compared to the test belts in which the rubber compositions of Comparative Examples 1 to 3 were used as surface layer belts. example'
Compared to test belts Nos. 4 to 6, the change in the surface layer of wear feeling over time, that is, the depth of cracks, was small, and the wear resistance was also excellent. This difference is particularly evident in Examples 8-10.

Example 11 to 15 A test belt was prepared in the same manner as in Example 6 except for the amount of polybutene in the rubber composition used as the surface belt. 180° due to the change in
The peel force and DINM thread after aging at 180° C. for 72 hours were measured, and the results are shown in FIG. □Also, Table 5 shows the composition ω of each polybutene.

As shown in Table 5 and Figure 1, Example 11, in which a rubber composition containing no polybutene was used for the surface belt, had excellent abrasion resistance, but was inferior in peeling force and poor processability, resulting in poor core performance. It was not easy to adhere to the body layer.

As the polarization of polybutene increases, the peeling force improves and the processability improves, but in Example 15, where a rubber composition containing 10fiQ parts of polybutene was used for the surface belt,
Abrasion resistance □ decreases. Therefore, it can be seen that the preferred amount of polybutene is 1 to 9 parts by weight.

Jitsutsu 4 and Examples 16 to 21 Rubber compositions were prepared using the same formulation and formulation m as in Example 4, except that the type and amount of organic peroxide were changed (
The amount of organic peroxide blended was 3 parts by weight only in Example 2, and 6 parts by weight in all other cases).

The rubber composition thus prepared was heated and pressure-treated at 170"C for 30 minutes, and the physical properties (tensile strength, elongation, tear force) of the obtained crosslinked rubber were determined according to JISK 63.
01, and the results are shown in a bar graph in FIG. Further, the physical properties of this vulcanized rubber after heat aging at 180° C. for 72 hours were measured in the same manner, and the results are also shown in FIG. In FIG. 2, the white part of c1 is the physical properties before aging, and the shaded area is the physical properties after aging. Furthermore, in each example, ■ indicates tensile strength, ■ indicates elongation, and ■ indicates tearing force, respectively.

The organic peroxides used in each example are shown below.

Example 16: 1,1-bis(t-butylperoxy)
=3.3.5-trimethylcyclohexane, Example 17
: 1.1-bis([-butylperoxy)cyclohexane, Example 18: [-butylperoxyisopropyl carbonate, Example 19: n-butyl-4,4-bis(t-butylperoxy)-valerate , Example 4 Rainbow cumyl peroxide, Example 20: α,α'-bis(t-butylperoxyisopropyl)benzene, Example 21: [-butylcumyl peroxide, as can be seen from FIG. The physical properties before and after aging differ depending on the type of oxide, but all are superior to the rubber compositions of Comparative Examples 1 to 3. Among the organic peroxides, dicumyl peroxide and .alpha.,.alpha.'-bis("-butylperoxyisopropyl)benzene, used in Examples 4 and 2o, are found to be preferred.

As explained above, ethylene-propylene copolymer rubber, specific diorganopolysiloxane, specific surface area 5O-
The conveyor belt of the present invention has white carbon having an IIi of 10 or more, an organic compound having 2111i or more of maleimide groups in one molecule, polybutene, a curing agent, and, in addition to this, a rubber composition containing polybutene if desired, disposed on the surface layer. Since the cover rubber has small natural crack growth, excellent physical properties such as tear strength, and excellent aging resistance, the heat resistance and life of the conveyor belt can be greatly improved. Furthermore, since white carbon is used, the volume resistivity can be freely selected over a wide range, and it can also be applied to applications such as insulating heat-resistant rubber plates.

Since no carbon black is used, the conveyor belt of the present invention also has the advantage of being able to freely select the hue and improving the product value by incorporating F1''9. Suitable for use in mW surroundings; applicable to many applications.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between polybutene content, 180° peel force, and DIN III wear Q after 72 hours at 180°C, and Figure 2 is a graph showing the physical properties (tensile strength) before and after aging in Example 4 and Examples 16 to 21. This is a bar graph showing the values of tensile strength, elongation, and tear force. In the figure, the white frame indicates the value before aging, the diagonal frame indicates the value after aging, ■ indicates the tensile strength, ■ indicates the elongation, and ■ indicates the value of the tear force. Each is shown below.゛Patent applicant Yokohama Rubber Co., Ltd. agent Ben]! I! Attorney Tatsuo Ito Representative Patent Attorney Tetsuya Ito

Claims (1)

[Claims] (I) (A) ethylene-propylene copolymer and/or
or an ethylene-propylene copolymer rubber consisting of ethylene-propylene terpolymer with a weight of 40 to 99%; Organopolysiloxane 6
100 parts of white carbon with a specific surface area of 50 Td/'g or more, (■) at least 2 maleimide groups in one molecule. 1. A heat-resistant conveyor belt, characterized in that a rubber composition containing 0.5 to 10 parts by weight of an organic compound having the following properties is disposed on the surface layer: a curing agent;