JP2019143040A - Crosslinked promoter master batch for acrylic rubber - Google Patents

Abstract

To provide a crosslinked promoter master batch for acrylic rubber, which suppresses winding around a roll at a higher rotational speed when a composition is produced, has excellent roll workability, and contains a high concentration of sodium stearate.SOLUTION: The crosslinked promoter master batch for acrylic rubber includes acrylic rubber, sodium stearate, and carbon black. In the crosslinked promoter master batch for acrylic rubber, the content of the sodium stearate is 50 to 63 mass%, the carbon black includes carbon black A having an average particle diameter of 90 to 700 nm, a nitrogen adsorption specific surface area of 5 to 20 m/g, and a DBP absorption amount of 30 to 50 cm/100 g and carbon black B having an average particle diameter of 10 to 120 nm, a nitrogen adsorption specific surface area of 20 to 200 m/g, and a DBP absorption amount of 40 to 150 cm/100 g, and a mass ratio A/B between the carbon black A and the carbon black B is 0.5 to 3.5.SELECTED DRAWING: None

Description

  The present invention relates to a crosslinking accelerator masterbatch for acrylic rubber containing sodium stearate as an active ingredient.

  In order to improve the dispersibility of powder chemicals such as a crosslinking agent and a crosslinking accelerator blended in the acrylic rubber composition, the forced dough may be passed through a screw strainer extruder or the like. At this time, scorch (initial crosslinking) may occur due to shear heat generation of the fabric. As a countermeasure, a masterbatch containing a high concentration of a crosslinking agent or crosslinking accelerator is prepared in a separate process, and the masterbatch is blended with the acrylic rubber composition to generate a lump of undispersed compounding chemicals. A way to avoid it is taken.

  For example, Patent Document 1 discloses a crosslinking accelerator masterbatch for acrylic rubber having improved dispersibility on a rubber fabric.

Japanese Patent Laying-Open No. 2015-71724

  Carbon black is usually added to the master batch of the crosslinking accelerator in order to increase the green strength and improve the workability. However, when carbon black is blended in the masterbatch composition of the crosslinking accelerator using a closed kneader or an open roll, if the carbon black with high reinforcement is blended, the masterbatch composition sticks to the surface of the metal roll. It becomes easy and workability | operativity falls. In particular, when the master batch composition is wound around a metal roll having a higher rotation speed, workability is significantly reduced.

  The present invention has been made in view of such a situation. That is, the problem of the present invention is to produce a crosslinking accelerator masterbatch for acrylic rubber that suppresses wrapping around a roll having a higher rotation speed, has excellent roll processability, and contains sodium stearate at a high concentration during production. Is to provide.

  In order to solve the above-mentioned problems, the present inventor has proceeded with studies on the types and blending conditions of carbon black used. As a result, it is effective to use two specific types of carbon black, to set the blending ratio of both to a specific range, and to set the content of sodium stearate, which is an active ingredient as a crosslinking accelerator, to a predetermined range. As a result, the present invention has been completed.

That is, the crosslinking accelerator masterbatch for acrylic rubber of the present invention contains acrylic rubber, sodium stearate and carbon black, the sodium stearate content is 50 to 63% by mass, and the carbon black is an average. particle size 90～700Nm, nitrogen adsorption specific surface area 5~20m ² / g, DBP (dibutyl phthalate) and carbon black a of absorption 30 to 50 cm ^3/100 g, average particle size 10 to 120 nm, a nitrogen adsorption specific surface area 20~200m ² / g, containing carbon black B of DBP absorption 40~150cm ³ / 100g, the weight ratio a / B of the carbon black a and the carbon black B is 0.5 to 3.5.

  In the crosslinking accelerator masterbatch for acrylic rubber of the present invention, the acrylic rubber is preferably a copolymer having an alkyl acrylate ester or an alkoxyalkyl acrylate ester as a main monomer component.

  The crosslinking accelerator masterbatch for acrylic rubber of the present invention suppresses wrapping around a roll having a higher rotation speed during production, and is excellent in roll processability. Moreover, the crosslinking accelerator masterbatch for acrylic rubber of the present invention contains sodium stearate which is an active ingredient as a crosslinking accelerator in a high concentration.

It is the graph which plotted content of sodium stearate with respect to mass ratio A / B of carbon black A and carbon black B in the masterbatch of an example and a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail. However, the scope of the present invention is not limited to the exemplary embodiments described below.

  The crosslinking accelerator master batch for acrylic rubber of the present embodiment (hereinafter sometimes referred to as “master batch”) is used by being added to a molding rubber composition using acrylic rubber. Acrylic rubber is widely used in applications such as oil seals, O-rings, hoses and the like because of its excellent heat resistance and oil resistance.

  The master batch of this embodiment contains acrylic rubber, sodium stearate, and carbon black. Hereinafter, each component will be described.

(Acrylic rubber)
Acrylic rubber is a copolymer having an acrylic acid alkyl ester or an acrylic acid alkoxyalkyl ester as a main monomer component, and is also referred to as ACM. Here, “main” means that the copolymer contains 50% by mass or more of the monomer component. The copolymer may or may not be copolymerized with a crosslinkable monomer having a functional group serving as a crosslinking point. In order to ensure long-term storage stability, an acrylic rubber that does not copolymerize a crosslinkable monomer is preferred. An example of such an acrylic rubber is Noxtile PA-102 manufactured by Unimatec Co., Ltd., which is excellent in kneadability.

  Examples of the acrylic acid alkyl ester include alkyl alkyl esters having 1 to 20 carbon atoms in the alkyl group. Specifically, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, propyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate , Stearyl acrylate, etc., preferably methyl acrylate, ethyl acrylate, and n-butyl acrylate.

  Moreover, as an acrylic acid alkoxyalkyl ester, the C1-C4 acrylic acid alkoxyalkylester whose alkoxy group is 1-4 is mentioned, for example. Specific examples include methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, methoxyethoxyethyl acrylate, etc., preferably methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate. It is.

  Moreover, as a crosslinkable monomer which has a functional group used as a crosslinking point, there exists a crosslinkable monomer or diene monomer which has an epoxy group, a carboxyl group, an active halogen group, a hydroxyl group, an amide group etc.

  Examples of the crosslinkable monomer having an epoxy group include vinyl glycidyl ether, allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

  Examples of the crosslinking point monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, itaconic acid mono Examples include alkyl esters.

  Examples of the crosslinkable monomer having an active halogen group include 2-chloroethyl vinyl ether, 2-chloroethyl acrylate, vinyl benzyl chloride, vinyl chloroacetate, and allyl chloroacetate.

  Examples of the diene monomer include ethylidene norbornene, dicyclopentadiene, 1,3-butadiene, isoprene, piperylene and the like.

  In addition to the acrylic acid alkyl ester, acrylic acid alkoxyalkyl ester, and crosslinkable monomer, the acrylic rubber may be copolymerized with other copolymerizable monomers as necessary. Although it does not specifically limit as another monomer which can be copolymerized, For example, styrene, acrylonitrile, ethylene, olefins, vinyl ethers etc. are mentioned.

  10-30 mass% is preferable and, as for content of the acrylic rubber in a masterbatch, 15-20 mass% is more preferable.

(Sodium stearate)
In this embodiment, sodium stearate is used as a crosslinking accelerator for acrylic rubber. Sodium stearate is conventionally known as a crosslinking accelerator for acrylic rubber, and examples of commercially available products include NS soap manufactured by Kao Corporation. As the crosslinking accelerator, those other than sodium stearate can be used in combination as long as the effects of the present invention are not impaired. Examples of crosslinking accelerators other than sodium stearate include aliphatic amine compounds, guanidine compounds, imidazole compounds, quaternary onium salts, tertiary phosphine compounds, weak acid alkali metal salts, diazabicycloalkene compounds, and the like. .

  The master batch of this embodiment contains sodium stearate in a high concentration. The content of sodium stearate in the master batch is 50 to 63% by mass. When the content of sodium stearate is within the above numerical range, a master batch excellent in roll processability can be obtained.

(Carbon black)
Carbon black is used to increase the green strength of the composition constituting the masterbatch and to improve processability.

  When carbon black is blended into the master batch composition, a closed kneader or an open roll is used. At this time, the present inventor has found that when carbon black having a high reinforcing property is blended, the master batch composition easily adheres to the surface of the metal roll and the workability is lowered. In particular, when the master batch composition is wound around a metal roll having a higher rotation speed, workability is significantly reduced. Therefore, the present inventor, in the production of the masterbatch, to suppress the winding around the roll having a higher rotational speed, in order to obtain a masterbatch composition excellent in roll processability, the type and blending conditions of carbon black Various studies were conducted.

As a result, the average particle size 90～700Nm, nitrogen adsorption specific surface area 5 to 20 m ² / g, carbon black A in DBP absorption amount 30 to 50 cm ^3/100 g, average particle size 10 to 120 nm, a nitrogen adsorption specific surface area 20~200m ² / g, was found that it is effective to use a carbon black B of DBP absorption 40~150cm ³ / 100g. Carbon black A had an average particle size 200 to 350 nm, a nitrogen adsorption specific surface area 5 to 10 m ² / g, preferably a DBP absorption amount 38~43cm ³ / 100g. Further, carbon black B has an average particle size 30 to 70 nm, a nitrogen adsorption specific surface area 25~60m ² / g, preferably a DBP absorption of 50 to 150 cm ^3/100 g. Here, the average particle diameter of carbon black can be measured using a transmission electron microscope (TEM). The nitrogen adsorption specific surface area of carbon black can be measured according to JIS K 6217: 1997. The DBP absorption amount of carbon black can be measured according to JIS K 6217: 1997.

  Furthermore, it has been found that it is effective to set the mass ratio A / B of carbon black A and carbon black B to 0.5 to 3.5. The mass ratio A / B of carbon black A and carbon black B is more preferably 1 to 3.

  Carbon black A is carbon black having high reinforcing properties, and carbon black B is carbon black having low reinforcing properties. By mixing and using these two types of carbon black at a predetermined mixing ratio, it is possible to suppress winding around the roll having a higher rotation speed.

Examples of carbon black A include furnace black. Furnace black is obtained by incomplete combustion of gas, oil or a mixture thereof in air. Typical properties of furnace black has an average particle size 10 to 120 nm, a nitrogen adsorption specific surface area 20 to 200 m ² / g, a DBP absorption 40~150cm ³ / 100g. Specific examples of such furnace black products include Cabot Show Black N330, Asahi Carbon Asahi # 60, Asahi # 55, Asahi # 35, Asahi Thermal, Tokai Carbon Co. Seast S, Seast SO. , Seast G-SO, Seast SVH, Seast 116 and the like.

Examples of carbon black B include thermal black. Thermal black is obtained by pyrolyzing natural gas. Typical properties of thermal black has an average particle size 90～700Nm, nitrogen adsorption specific surface area 5 to 20 m ² / g, a DBP absorption of 30 to 50 cm ^3/100 g. Specific examples of such thermal black products include Thermax N990 manufactured by CanCarb.

  Other examples of carbon black include channel black, acetylene black, and the like. If the above characteristics are satisfied, the carbon black can be used similarly. Examples thereof include acetylene black manufactured by Denka.

  10-50 mass% is preferable and, as for total content of carbon black in a masterbatch, 15-30 mass% is more preferable. Moreover, it is preferable that the compounding quantity of carbon black with respect to sodium stearate is 20 mass% or more.

  In addition to the above-mentioned components, the master batch composition may be appropriately added with various additives such as known lubricants, plasticizers, softeners, fillers, anti-aging agents, reinforcing agents, and stabilizers as necessary. Can do.

  Examples of the lubricant include natural wax, polyethylene wax, silicone wax, paraffin wax, fatty acid, fatty acid amide, fatty acid ester, fatty acid metal salt, and fatty acid nitrogen derivative.

  Examples of the natural wax include trade name VPA No.2. Examples of the polyethylene wax include trade name High Wax 110P. Examples of the silicone-based wax include trade names KF96, Sh200, Stratol WS280, and the like. Examples of the paraffin wax include trade name Antilux. As fatty acids, for example, trade name Lunac S-30, as fatty acid amides, for example, trade name Daiamid O-200, etc., as fatty acid esters, for example, trade names such as stractol WB212, stractol WB222, Greg G-8205, etc. Can be mentioned.

  Examples of the plasticizer include bis (2-ethylhexyl) phthalate, di-n-octyl phthalate, dibutyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, diisononyl phthalate, ethyl phthalyl ethyl glycolate, etc. Bis (2-ethylhexyl) sebacate, di-n-butyl sebacate, trimellitic acid derivatives tris (2-ethylhexyl) trimellitate, triisooctyl trimellitate, tri-2-ethylhexyl trimellitate, tri-n-octyltri Melitate, tridecyl trimellitate, triisodecyl trimellitate, di-n-octyl-n-decyl trimellrate, etc. Phosphoric acid derivatives trimethyl phosphate, triethyl phosphate, tributyl phosphate Feto, triphenyl phosphate, can be mentioned tricresyl phosphate and the like. Examples of other plasticizers include polyether ester, polyether thioether, polyester thioester and the like.

  Examples of the mineral oil softener include paraffin process oil, naphthene process oil, aromatic process oil and the like.

(Manufacturing method of master batch)
As a kneading apparatus used for producing the master batch, it is preferable to use a closed kneading apparatus in order to block the influence of the atmosphere as much as possible. The kneading apparatus may be a batch type or a continuous type. Examples of the batch kneader include a pressure kneader and a Banbury mixer. Examples of the continuous kneader include a single screw extruder, a twin screw extruder, and a feeder ruder.

  Hereinafter, although an example and a comparative example explain the present invention, these examples do not limit the present invention.

(Master batch raw material)
Acrylic rubber: Unimatec Noxtite PA402S
Sodium stearate: NS soap manufactured by Kao Corporation Carbon black A: Seast G-SO manufactured by Tokai Carbon Co., Ltd.
Carbon Black B: Thermax N990 made by CanCarb

(Manufacture of master batch composition)
Using the above masterbatch raw material, add sodium stearate and carbon black to acrylic rubber with the composition shown in Table 1, knead at 120 ° C. for 10 minutes using a 1 L hermetic pressure kneader, and discharge. The master batch composition was prepared by pelletizing.
The obtained master batch composition was evaluated for the following items.

(Roll processability)
Each master batch composition was kneaded using a 12-inch open roll, and roll processability was evaluated according to the following criteria.
○: Good workability △: Adhesive and difficult to work ×: Adhesive and cannot be removed unless the roll is stopped

(Roll rollability)
The rotational speed of the faster roll of the 12-inch open roll was set to 17 rpm, and the rotational speed of the slower roll was set to 14 rpm. Each master batch composition was kneaded using a 12-inch open roll, and it was evaluated whether the roll was wound around the higher rotation speed or the roll rotation speed was lower.

  As can be seen from the evaluation results in Table 1, the master batch compositions of Example 1 and Example 2 have good roll processability, and the roll wrapping property winds around the roll with the lower rotation speed. there were.

  On the other hand, in the master batch composition of Comparative Example 1, the mass ratio A / B of carbon black A and carbon black B is less than 0.5, the adhesiveness to the roll is high, and the roll processability is inferior. It was wound around the roll with the higher rotation speed. The master batch composition of Comparative Example 2 has a mass ratio A / B of carbon black A and carbon black B of less than 0.5 and a high content of sodium stearate. It was inferior in property and wound around a roll having a higher rotation speed in roll winding property. The masterbatch compositions of Comparative Example 3 and Comparative Example 4 were slightly inferior in roll processability because the sodium stearate content was higher than 63% by mass. In the master batch composition of Comparative Example 5, the mass ratio A / B of carbon black A and carbon black B exceeded 3.5, and the roll processability was slightly inferior. In the master batch composition of Comparative Example 6, the mass ratio A / B of carbon black A and carbon black B exceeded 3.5, and the roll processability was poor.

  FIG. 1 is a graph in which the content of sodium stearate is plotted against the mass ratio A / B of carbon black A and carbon black B in the master batches of Examples and Comparative Examples. E1 and E2 correspond to Example 1 and Example 2, respectively, and C1 to C6 correspond to Comparative Example 1 to Comparative Example 6, respectively.

Claims (2)

A crosslinking accelerator masterbatch for acrylic rubber containing acrylic rubber, sodium stearate and carbon black,
The content of the sodium stearate is 50 to 63 mass%,
It said carbon black has an average particle size 90～700Nm, nitrogen adsorption specific surface area 5 to 20 m ² / g, carbon black A in DBP absorption amount 30 to 50 cm ^3/100 g, average particle size 10 to 120 nm, a nitrogen adsorption specific surface area 20 200 m ² / g, containing carbon black B of DBP absorption 40~150cm ³ / 100g,
A crosslinking accelerator masterbatch for acrylic rubber, wherein the mass ratio A / B of the carbon black A and the carbon black B is 0.5 to 3.5.   The crosslinking accelerator masterbatch for acrylic rubber according to claim 1, wherein the acrylic rubber is a copolymer having an alkyl acrylate ester or an alkoxyalkyl acrylate ester as a main monomer component.

Images