JPH0430981B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical Field> The present invention relates to an improved rubber composition using a non-rubber substance obtained from serous fluid by-produced during the production of natural rubber, and in particular to an ethylene propylene rubber composition that has improved physical properties without impairing the characteristics of ethylene propylene rubber. Regarding. <Prior Art> Ethylene propylene rubber includes a copolymer of ethylene and propylene (EPM) and a terpolymer of ethylene, propylene, and some diene component (EPDM). As is clear from its structure, EPM is a completely non-diene rubber with excellent aging resistance, ozone resistance,
It exhibits outstanding heat resistance, but because there are no double bonds in the main chain, sulfur vulcanization is not possible, and crosslinking must be done exclusively with organic peroxides. EPDM, on the other hand, is copolymerized with a diene component (also called a third component, in which dicyclopentadiene, ethylidene norbornene, 1,4-hexadiene, etc. are used), and therefore can be subjected to normal sulfur vulcanization. Of course, as the diene content increases, it is natural that EPDM's original properties, such as weather resistance and ozone resistance, deteriorate. In terms of electrical performance, EPDM has become the mainstream in the field of high-voltage cables because it has excellent corona resistance and tracking resistance. Furthermore, it has good rebound resilience, so it can be used for more rubber applications, general rubber products, industrial rubber products, automotive rubber products, etc.
Its uses are extremely wide, including rubber products for construction. The fact that the specific gravity of the polymer is 0.86 to 0.87, the lowest among commercially available rubbers, is an important point in evaluating EPM and EPDM as general-use rubbers. Although EPDM certainly has many excellent properties in terms of physical properties, it cannot be said that it necessarily has satisfactory performance from a processing perspective. Furthermore, it has mechanical strength and is brittle against compressive fatigue, and improvements are desired. On the other hand, in the natural rubber manufacturing process, the remaining liquid after removing the coagulated rubber is an aqueous solution called serum, which is often discarded as is, and contains non-containing substances such as proteins and carbohydrates. There was a problem of environmental pollution due to the rotting rubber content. There is a method of treating the serum in a septic tank, but it is not very effective as it costs a huge amount of money, emits a strong putrid odor, and poses a pollution problem. If this serum can be used as an industrially useful substance, the efficiency of the rubber industry will increase and it will be effective in saving resources. <Object of the Invention> The object of the present invention is to effectively use natural rubber latex serum industrially to improve mechanical strength and compression fatigue resistance without impairing the characteristics of ethylene propylene rubber. <Structure of the Invention> The present invention is an ethylene propylene rubber characterized in that ethylene propylene rubber is blended with 0.5 pHR or more of a powdered non-rubber component obtained from the remaining serum after coagulating and removing the rubber component of natural rubber latex. A composition is provided. Here, an ethylene propylene rubber composition in which the powdery non-rubber component is blended in an amount of 0.5 to 10 pHR relative to ethylene propylene rubber is preferable. The present invention will be explained in more detail below. The powdered non-rubber component obtained from the natural rubber latex serum used in the present invention is a substantially spherical powder, and preferably has an average particle size of 10 to 100 microns.
The composition of ingredients varies depending on the ingredients of the raw material natural rubber latex and cannot be strictly limited, but it is approximately 50% crude proteins such as α-globulin and hevein, approximately 30% carbohydrates, K, Mg, Cu, Fe, Na,
Ash (inorganic components) such as Ca, P, etc. is about 15%, fat is about 2%, water is about 3%, fiber is 0%, and other trace components, and the crude protein content is quite high. It's on par. The method for producing powdered non-rubber components obtained from natural rubber latex serum uses the remaining serum obtained by coagulating and removing the rubber content from natural rubber latex as a raw material using formic acid, acetic acid, sulfuric acid, etc. as a coagulant. . One example of the components of natural rubber latex is shown in Table A.

[Table] The product obtained by coagulating rubber hydrocarbons and removing them from this natural rubber latex is called serum, and in general, industrially, serum usually contains a very small amount of rubber. The components of the serum vary depending on the components of the natural rubber latex, and various materials can be used as raw materials, but the serum contains about 0.5 wt% of rubber content and about 2 to 5 wt% of non-rubber content. This may be used after removing the rubber component by centrifugation or the like. A non-rubber content (solid content) concentration of 2 to 80 wt% can be used, but from the viewpoint of production efficiency, manufacturing cost, and process control, it is preferable to use serum with a solid content of 15 to 70 wt% as a raw material. preferable. Normally, the solid content of the serum obtained in the natural rubber manufacturing process is approximately 2 to 5 wt%.
Therefore, it is preferable to perform pretreatment to concentrate the solid content to about 25 to 70 wt% using methods such as an evaporator, centrifugation, and filtration. The serum is supplied in the form of minute droplets into a spray-drying container in a high-temperature atmosphere of 150 to 250°C, and water is instantly evaporated to form a powder. For this reason, a closed system spray drying method is used. The closed system spray drying method atomizes a liquid sample and instantly contacts the atomized droplets with hot air to evaporate water and dry them into powder. There are two types: the nozzle type, which uses a nozzle to atomize the particles, and the disk type, which uses a high-speed rotating disk to atomize the particles. Although any method may be used, the disk type is preferable because it is efficient. The rotation speed of the disk is
10000~30000rpm, nozzle pressure 0.5~2.0Kg/
^cm2 is good. If the rotation speed or pressure is outside this range, the size of the powder obtained will be outside the range of 10 to 100μ,
If the powder is less than 10μ, it absorbs moisture and is likely to re-solidify, or it may adhere to or aggregate on the inner wall of the spray dryer, resulting in a poor recovery rate, and the resulting powder will be lump-like and not atomized. 100μ
If the non-rubber component is used industrially, it will be difficult to dissolve in water or solvents, and the bulk will become large, making transportation inconvenient. The drying temperature in the spray dry container is 150-250℃
In particular, it is preferable to keep the sample inlet drying temperature at 150 to 250°C and the sample outlet temperature to 50 to 130°C. If the sample drying temperature is higher than this temperature range,
The resulting non-rubber component changes in quality due to heat.
Non-rubber components include proteins, sugars, resins, etc., all of which are easily affected by heat. The actual sample temperature is about 100°C lower than the inlet temperature, so from that point of view the drying temperature cannot be set too high. On the other hand, if the temperature is lower than this temperature range, sufficient drying will not be possible, and instead of becoming powdery, it will aggregate and become lump-like. The ethylene propylene rubber used in the present invention may be any copolymer of ethylene and propylene (EPM) or a terpolymer of ethylene, propylene, and a diene component (EPDM). EPDM can be divided into three types depending on the third component, the diene component. There are three types: ethylidene norbornene, dicyclopentadiene, and 1,4-hexadiene. The amount of the third component can be expressed by the so-called iodine value, and the iodine value of EPDM is usually in the range of 5 to 26%, but 10 to 12% is the standard, and 25 to 26% is the so-called high iodine value. It is called diene type. The ratio of powdered non-rubber components obtained from the remaining serum after coagulating and removing the rubber components of natural rubber latex to ethylene propylene rubber is 0.5 pHR.
or more preferably 0.5 to 10 pHR (per hundred
rubber: parts by weight based on 100 parts by weight of rubber). If it is less than 0.5 pHR, the effect of the present invention cannot be obtained, and if it exceeds 10 pHR, Rheo.Max.T (maximum rheotorque) decreases and physical properties such as Ts (tensile strength) deteriorate. Generally, when a powdered non-rubber component obtained from the remaining serum after coagulating and removing the rubber component of natural rubber is added to a general-purpose polymer (NR, IR, SBR, etc.),
As the amount added increases beyond 2pHR, Ts, E, Mod
Physical properties deteriorate, such as a decrease in heat generation, an increase in heat generation, and a deterioration of wear resistance. However, when powdered non-rubber components obtained from the remaining serum after coagulating and removing the rubber components of natural rubber are added to ethylene propylene rubber, heat resistance, weather resistance,
Without impairing the characteristics of ethylene propylene rubber such as ozone resistance, internal heat generation during compression of vulcanized rubber can be suppressed and permanent deformation can be reduced. Also, tan δ (loss tangent) and E ^* (complex elastic modulus) decrease. <Example> A more specific explanation will be given below using examples. (Examples and Comparative Examples) The components having the composition shown in Table 1 were kneaded using a Banbury mixer to form a plate material of 150 x 150 x 2 mm.
Vulcanization was carried out under the conditions of 30°C x 30' to obtain specimens numbered as shown in Table 1.

【table】

[Table] The following tests were conducted using the specimens shown in Table 1. The results are shown in Table 3. Rubber test method Unvulcanized rubber test (1) Mooney viscosity test; MV JIS K 6300
ML ₁₊₄ @100℃ (2) Rheometer test Using Toyo Seiki rheometer Rheo.Max.T.@160℃ (maximum torque) Rheo.Min.T.@160℃ (minimum torque) T ₅ T ₉₅ vulcanization Rubber test (1) Tensile test Tensile strength (Ts) JIS K 6301 160℃×10 Elongation (E1) JIS K 6301 Tensile stress (M) JIS K 6301 M ₁₀₀ : 100% modulus M ₃₀₀ : 300% modulus (2) Hardness (Hs JISA) JIS K 6301 (3) Aging test (Aging) JIS K 6301 100℃×48H Measure Ts, E, M ₁₀₀ , Hs after aging (4) Resilience (Lupke) JIS K 6301 (5 ) Heat generation test Dynamic internal heat generation (heat build up; HBU) Dynamic permanent set (permanent set; ps) Gutudoritsu type flexometer rotation speed 1800 rpm, stroke 4.44 mm Load 25 Kg (6) Compression permanent set (C-set) JIS K 6301 70℃
×22H (7) Loss tangent (tanδ) Viscoelastic spectrometer extension type strain 10±2%, 20Hz, 20℃ (8) Complex modulus (E ^* ) Viscoelastic spectrometer extension type strain 10±2%, 20Hz, 20℃ (9) DIN wear amount (index) DIN wear tester Load 1Kg Length 411 do not have)

【table】

【table】

【table】

[Table] From the results in Table 3, the ethylene propylene rubber composition of the present invention has the following properties. Mechanical properties of ethylene propylene rubber (Ts,
E, M ₁₀₀ , M ₃₀₀ , Hs), mechanical properties aging resistance (Aging Ts, E, M ₁₀₀ , Hs) and heat resistance, weather resistance, ozone resistance (tan δ, E ^* ,
DIN wear amount (static ozone) is not impaired by the addition of additives. Compression internal ripening and dynamic set are reduced (HBU value is small) (PS value is small). Also, tan δ and E ^* decrease. <Effects of the Invention> The present invention is a composition in which ethylene propylene rubber is blended with 0.5 pHR or more of a powdered non-rubber component obtained from the remaining serum after removing the rubber component of natural rubber latex. When processed into belts and the like, the dynamic characteristics of the belts and the like are improved. 1. Internal heat generation due to repeated compression of vulcanized rubber is suppressed and permanent deformation is reduced without impairing the characteristics of ethylene propylene rubber (heat resistance, weather resistance, ozone resistance). Furthermore, tan δ and E〓 decrease. 2 There is no change in rebound resilience. 3 Compression set does not increase even with the addition of additives.

Claims (1)

[Scope of Claims] 1. An ethylene propylene rubber composition comprising ethylene propylene rubber and a powdered non-rubber component obtained from the remaining serum after coagulating and removing the rubber component of natural rubber latex at a pH of 0.5 pHR or more. 2. The ethylene propylene rubber composition according to claim 1, wherein the amount of the powdered non-rubber component is 0.5 to 10 pHR based on the ethylene propylene rubber.