JPS61258846A - Composition for compounding rubber and rubber kneading method - Google Patents

Abstract

PURPOSE:A composition for compounding rubber, obtained by incorporating a specific amount of mountain leather having high adsorptivity with a rubber compounding ingredient and having good kneading operability and improved dispersibility in rubber. CONSTITUTION:A composition for compounding rubber obtained by incorporating and mixing (A) 100pts.wt. rubber compounding ingredient having <115 deg.C melting point, e.g. tetraethylthiuram disulfide, with (B) 10-100pts.wt., preferably 30-70 pts.wt. mountain leather having <=100 mesh particle diameter, is added to rubber and kneaded therewith. Alternatively, the components (A) and (B) in amounts to give the above-mentioned ratio are added and mixed with the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for uniformly mixing rubber compounding compositions with good kneading workability and dispersibility, as well as rubber compounding agents that have a low melting point and tend to become molten during mixing. It relates to a method of kneading into rubber.

When kneading various rubber compounding agents with rubber using conventional technology rolls or Banbury mixers, rubber compounding agents with low melting points such as tetraethylthiuram disulfide melt when kneaded at temperatures above their melting points, or the rotor of the Banbury mixer. In addition, even when a rubber compounding agent with a low melting point is mixed with one with a high melting point and kneaded, the rubber compounding agent with a low melting point will melt and be adsorbed by the compound with a high melting point, forming lumps and inhibiting its dispersion into the rubber. , Therefore, it also has an adverse effect on the physical properties of the rubber.

In order to eliminate such adverse effects, a method has been proposed in which a vulcanization accelerator with a melting point of less than 120°C is mixed with white carbon, and the mixture is mixed with powder or oil, and then added to rubber in the form of a paste and kneaded. JP-A-57-125028).

However, white carbon has a true specific gravity of 2°0 to 2.
．． If it is less than 15 parts by weight of the fluffy light fine powder of 2 and 100 parts by weight of the low melting point vulcanization accelerator, the adsorption of the molten low melting point vulcanization accelerator will be insufficient, and if it exceeds 35 parts by weight. , fluffy and sticky, making mixing difficult. Furthermore, since white carbon has a reinforcing effect on rubber, its mixing ratio is limited because it affects other properties of the rubber product. In addition, if a large amount of oil is added to eliminate this fluffy state and prevent the powder from scattering, it will be adsorbed by the white carbon, and when kneading at a temperature above the melting point, the molten vulcanization accelerator will be sufficiently adsorbed. Therefore, there is a drawback that the amount of oil must be reduced even at the expense of scattering properties.

Problems to be Solved by the Invention An object of the present invention is to provide a rubber compounding composition that has low scattering properties, good cross-wire workability, and improved dispersibility in rubber, and a rubber compounding agent with a low melting point. The object of the present invention is to provide a method for uniformly kneading into rubber.

Means for Solving the Problems As a result of intensive research to solve the above-mentioned drawbacks, the inventors of the present invention found that when a specific amount of highly adsorbent mountain bark is added to a rubber compound with a melting point of less than 115°C, it becomes rubbery. It was discovered that during the kneading process, the mountain bark powder immediately adsorbs the molten rubber compounding agent, resulting in a rubber compounding composition with little scattering, good kneading workability, and excellent dispersibility in rubber. However, based on this knowledge, the present invention was completed.

That is, the present invention provides a rubber compounding composition comprising a rubber compounding agent having a melting point of less than 115°C and about 10 to 100 parts by weight of mountain bark per 100 parts by weight of the compounding agent, and a rubber compounding composition containing a rubber compounding agent having a melting point of less than 115°C.
The present invention relates to a method for kneading rubber, which comprises adding a rubber compounding agent at a temperature of less than 5° C. and about 10 to 100 parts by weight of mountain bark per 100 parts by weight of the compounding agent to rubber and kneading the mixture.

Rubber compounding agents with a melting point of less than 115°C used in the present invention include, for example, tetraethylthiuram disulfide (melting point 68°C), tetramethylthiuram monosulfide (melting point 108°C), dipentamethylenethiuram tetrasulfide (melting point 113°C), N -Cyclohexylbenzothiazyl-2-sulfenamide (melting point 98°C), N, N-
Dicyclohexylbenzothiazyl-2-sulfenamide (melting point 101°C), N-oxydiethylenebenzothiazyl-2-sulfenamide (melting point 83°C), N,N-
Diisopropylbenzothiazyl-2-sulfenamide (melting point 55°C), N-tert-butylbenzothiazyl-2-sulfenamide (melting point 107°C), diethylthiourea (melting point 73°C), dibutylthiourea (melting point 63°C) ), trimethylthiourea (melting point 78℃), tetramethylthiourea (melting point 73℃) and other vulcanization accelerators, vulcanizing agents with a melting point below 115℃, anti-aging agents, curing agents, vulcanization retarders, etc. can be given.

The mountain bark used in the present invention is a general term for formite clay minerals having a large number of active hydroxyl groups on the surface, and is composed of hydrated magnesium silicate.
sepiolite (Sep
io 1 ite)・hydrated magnesium alumina・
Silicate (hydr-ous magnesium
Attapulgite or palygite (aluminum 5ilicate)
orskite). It is usually called mountain leather, mountain cork, mountain wood, etc.

Mountain bark is usually used in powder form, and its particle size is approximately 100
No more than about 200 meshes, preferably no more than about 200 meshes.

The rubber compounding composition of the present invention can be obtained by mixing the above-mentioned rubber compounding agent having a melting point of less than 115° C. and mountain bark. Mixing operations are, for example, Brengu. This is carried out using appropriate means such as a mixer or a kneader.

The blending ratio is about 10 to 100 parts by weight of mountain skin per 100 parts by weight of the rubber compound, but preferably about 30 to 100 parts by weight.
The amount is about 70 parts by weight.

If the amount of lint is less than 10 parts by weight, it will not be able to sufficiently adsorb the rubber compounding agent that melts during cross-wire operation, and the mixed composition will be in a molten state. On the other hand, if it exceeds 100 parts by weight, it is not economical.

The rubber compounding composition of the present invention obtained in this way is
It is usually in a powder state, but it may be moistened or made into a paste, for example with a process oil or a plasticizer. Also process oil.

It may be formed into an appropriate shape such as granules using a plasticizer or water.

Examples of process oils used during molding include petroleum softeners such as paraffinic process oils, naphthenic process oils, and aromatic process oils, and examples of plasticizers include dibutyl phthalate and di(2- Phthalic acid derivatives such as ethylhexyl) phthalate and dioctyl phthalate, and di(2-ethylhexyl)adipate.

Examples include adipic acid derivatives such as diisodecyl adipate, and derivatives of sebacic acid, maleic acid, fumaric acid, trimellitic acid, oleic acid, stearic acid, and the like.

Water may be used instead of the above process oil and plasticizer. If water is used, a process of removing water from the molded product is required, so it is preferable to use process oil or a plasticizer.

The amount of process oil, plasticizer, or water used during molding is approximately 0.5 α to 0.5 parts by weight when the amount of mountain bark is α weight part.
It is about 2.0α parts by weight. If the amount of process oil, plasticizer, or water is less than 0.5 parts by weight, the wettability of the powder will be insufficient, and when molded, a satisfactory molded product may not be obtained. On the other hand, if the amount exceeds 2α parts by weight, the absorbency of the mountain skin, process oil, plasticizer, or water will be impaired, making it impossible to achieve the original purpose of adsorbing the molten rubber compound and retaining its shape. There is.

When molding, it can be carried out by any means such as a pellet machine, an extrusion granulator, etc. Its shape includes, for example, a granular one, and its size can be adjusted arbitrarily, but it usually has a diameter of about 0.5 to 3
The length is approximately 2 to 10 mm.

The rubber compounding composition of the present invention obtained in this way is
Kneaded into rubber. An appropriate amount is used depending on the type of compounding agent having a melting point of less than 115°C.

In the present invention, a composition for rubber compounding may be prepared by mixing mountain bark and a rubber compounding agent having a melting point of less than 115°C in a specific ratio as described above. The same effect as described above can be obtained even if less than 10% of the rubber compounding agent is directly added to the rubber in the above ratio and kneaded. In this case, it is preferable to add the mountain skin and the rubber compounding agent at the same time or immediately after adding the mountain skin.

An example of target rubber is natural rubber.

Diene-based rubber such as butadiene-styrene rubber, butadiene-acrylonitrile rubber, polybutadiene rubber, polyisoprene rubber, chlorine-containing rubber such as chloroprene rubber and epichlorohydrin rubber, polysulfide-based rubber such as thiocol, ethylene-propylene rubber, chlorosulfonated rubber, etc. Olefins such as polyethylene.

Yoiki silicon compound type, fluorine-containing compound type, urethane type,
Any raw material rubber such as vinyl-based synthetic rubber may be used.

The kneading operation can be carried out using, for example, two rolls or a Banbury mixer.
This is carried out by known means such as.

"Effect of the invention" According to the present invention, the following effects can be achieved.

(1) The mountain skin adsorbs the rubber compounding agent and has extremely good shape retention. In addition, compared to the case where white carbon is used, mountain bark has far less scattering properties, reduces adhesion to equipment, and reduces loss of rubber compounding agents, improving the working environment. Furthermore, since it has good fluidity when being charged into and discharged from a hopper, automatic metering is possible without clogging the equipment.

(2) The interaction between the mountain bark and the rubber compounding agent promotes dispersion into the rubber.

(3) Since the effect of the mountain skin dispersed in the rubber on the physical properties of the rubber is small, there are few restrictions on the amount used.

Particularly when molded into granules, it is easy to handle and has good dispersibility in MOCOM.

Next, the present invention will be explained in more detail with reference to Examples.

In the examples, parts indicate parts by weight.

Example 1 Tetraethylthiuram disulfide (Suncella TE
T: 100 parts of Sanshin Kagaku Kogyo Co., Ltd. and Seviolite powder (particle size of 200 mesh or less, Need Plus sP:
After thoroughly mixing the mixture with 52 parts of Takeda Pharmaceutical Co., Ltd. in a Ni-Goo, 32 parts of dioctyl phthalate was added and further mixed. This composition was extruded with a disc beretter (manufactured by Fuji Paudal Co., Ltd., disc mesh diameter: 2 mm), granulated into pellets, and sieved through a 50 mesh wire mesh to form pellets with a diameter of 2 mm and a length of 3 to 7 mm. Cylindrical granules were obtained.

Using this granular material, a comparative vulcanization test was conducted with tetraethylthiuram disulfide alone. The compounded rubber in Table 1 is
Table 2 shows the results of testing the effects on Mooney scorch, vulcanization rate, and rubber physical properties after kneading 80 parts at 5° C. using a 6″φ×12″ test roll.

Mooney Scorch is JIS K 6300 (1974
), the Mooney scorch time ts (minute 3 seconds), which is the time required for the viscosity to rise by 5 points from the lowest viscosity at 125° C., was determined. The vulcanization characteristics were determined from the vulcanization curves at 150°C and 160°C using a JSR type Curelastometer (dice: 2mm, amplitude ±3°), and the induction time t+o (minutes).

seconds), proper vulcanization time t,. (minute 1 second), vulcanization speed t,.

-t+.

(minute 1 second) was calculated. The vulcanized rubber was press-cured at 160°C for 10 minutes using a dumbbell-shaped No. 3 test piece.
Tensile test was conducted in accordance with K 6301 (1975).

Table 1 NBR (medium high nitrile) 100 parts SRF carbon black 50 Dioctyl phthalate lO Stearic acid
1〃 Zinc white No. 3 5〃 Sulfur o, 5〃 Anti-aging agent TM
DQ 2.0=vulcanization accelerator CM”)
, 1.2 ~ Compounding agent of the present invention')
3.82-1) 2,2.4-)tumethyl-1,2-dihydroquinoline (polymer) 2) N-cyclohexylbenzothiazyl-2-sulfenamide 3) Tetraethylthiuram disulfide: 2. 1
It is 0 copies.

From the test results, the kneaded rubber obtained in the example has smaller variations in tensile strength, elongation, and tensile stress than the comparative example using tetraethylthiuram disulfide alone, which indicates that it has a better dispersion state. Recognize.

Furthermore, it was found that sepiolite had little effect on the scorch time (t), vulcanization rate, and physical properties of the vulcanized rubber.

Table 2 1) Example 2 Using 2.10 parts of tetraethylthiuram disulfide alone N-cyclohexylbenzothiazyl-2-sulfenamide (Suncella 0: manufactured by Sanshin Kagaku Kogyo Co., Ltd.) 100
part, sepiolite powder similar to that used in Example 1 5
0 parts and 50 parts of naphthenic process oil (Sonic Process Oil R-25+Kyodo Sekiyu Co., Ltd.) were mixed and granulated in exactly the same manner as in Example i, and the diameter was 2 mm and the length was 3 to 7 mm.
A cylindrical granule of mm in size was obtained.

This granule was converted into N-cyclohexylbenzothiazyl-2-
It is placed on the surface of a metal plate maintained at 105 to 110 °C, which is higher than the melting point of sulfenamide, to maintain its shape when melted.
A comparison was made with N-cyclohexylbenzothiazyl-2-sulfenamide alone (comparative example). The test results are shown in Table 3.

From the upper table of Table 3, it can be seen that the granules obtained in Examples maintain a solid state that is suitable for rubber kneading operations even at temperatures higher than the melting point of N-cyclohexylbenzothiazyl-2-sulfenamide. I know what you're doing.

Example 3 and Comparative Examples Various inorganic photonic agents (fillers) shown in Table 4 were mixed in a ratio of 100 parts of tetraethylthiuram disulfide and 67 parts of filler. 85 parts of each of these compositions were placed on the surface of a metal plate maintained at 2° C., and the adsorption of molten tetraethylthiuram disulfide to various fillers and shape retention after complete adsorption were compared and tested. The results are shown in Table 4.

Table 4 ■) Need Plus SP: Manufactured by Takeda Pharmaceutical Co., Ltd. (Dibutyl phthalate oil absorption 200ml/100g) 2) Silver W: Manufactured by Shiraishi Kogyo Co., Ltd. (Dibutyl phthalate oil absorption 11
83ml/1. OOg) 3) Shiroenka CC = manufactured by Shiraishi Kogyo Co., Ltd. (dibutyl phthalate oil absorption: 30 m1/100 g) 4) Aluminum hydroxide C-301: manufactured by Sumitomo Aluminum Smelting Co., Ltd. (dibutyl phthalate oil absorption: 85 m1/1)
00g) Example 4 and Comparative Example The scattering properties of a composition prepared by mixing tetraethylthiuram disulfide, Seviolite, and a plasticizer in the proportions shown in Table 5 were tested in comparison with that of white carbon (comparative example).

For the test, each sample was placed in a cylindrical sample case with a lid (inner diameter 55 mm, height 70+ nm) with an internal capacity of 150 m1, the lid was closed, and the sample was vigorously shaken up and down 10 times, then the lid was immediately opened to check the scattering properties of the sample. Judging with the naked eye.

Table 5 ■) Need Plus SP: Manufactured by Takeda Pharmaceutical Co., Ltd. 2) Nip Seal VN3: Manufactured by Nippon Silikani Co., Ltd. 3) Diocdylphthalate 4) Judgment criteria: ○ No scattering △ Slightly scattering × Scattering 181 parts of the rubber masterbatch shown in Examples 5, 6.7 and Comparative Example Table 6, which have high
After kneading 80 parts for 1 minute at 5°C using a 12" test roll, tetraethylthiuram disulfide and sepiolite powder similar to that used in Example 1 were directly added to the kneaded rubber in the proportion shown in Table 7. They were added at the same time and kneaded.

Table 6 NBR (medium high nitrile) 100 parts SRF carbon black 65 Dioctyl phthalate 15 Stearic acid
1. Table 7 shows the results of a comparative evaluation of roll processability during kneading with that of tetraethylthiuram disulfide alone.

Table 7 1) Evaluation of molten state: O: The molten TET was mostly adsorbed on sepiolite, and the kneading workability was good.

×TET in the form of oil adheres to the rolls, and the compounded rubber also slips, resulting in poor kneading workability.

Example 8 Diethylthiourea (Suncella EUR: manufactured by Sanshin Kagaku Kogyo Co., Ltd., melting point 73°C) and sepiolite 1) were mixed in the proportions shown in Table 8. Using 0.5g of each composition, 85±2
As a result of testing the shape retention at ℃ (q) according to Example 3, the melted state was muddy to powdery, had little stickiness, and had good shape retention.

Table 8

Claims (2)

[Claims] (1) Rubber compounding agent with a melting point of less than 115°C and the compounding agent 100
A rubber compounding composition containing about 10 to 100 parts by weight of mountain bark. (2) Rubber compounding agent with a melting point of less than 115°C and the compounding agent 100
A method for kneading rubber, which comprises adding about 10 to 100 parts by weight of mountain bark to rubber and kneading the mixture.