KR20190101285A - Crosslinker masterbatch for hydrogenated nitrile rubber, hydrogenated nitrile rubber composition and cross-linked hydrogenated nitrile rubber molded article - Google Patents

Abstract

Provided are an organic peroxide master batch for hydrogenated nitrile rubber, which is capable of resolving a problem in a processing work that the hydrogenated nitrile rubber is separated from a roll during a kneading work due to the high content of organic peroxide, a hydrogenated nitrile rubber composition using the master batch, and a cross-linked hydrogenated nitrile rubber molded article. According to the present invention, the organic peroxide master batch for hydrogenated nitrile rubber comprises the hydrogenated nitrile rubber, 1,3-bis(tert-butyl peroxy isopropyl)benzene and carbon black, wherein the amount of combined acrylonitrile of the hydrogenated nitrile rubber is less than 25 mass%, the content of organic peroxide is 10 to 30 mass%, and the content of carbon black is 10 to 30 mass%.

Description

CROSSLINKER MASTERBATCH FOR HYDROGENATED NITRILE RUBBER, HYDROGENATED NITRILE RUBBER COMPOSITION AND CROSS-LINKED HYDROGENATED NITRILE RUBBER MOLDED ARTICLE}

The present invention relates to a crosslinking agent masterbatch for hydrogenated nitrile rubber, a hydrogenated nitrile rubber composition and a hydrogenated nitrile rubber crosslinked molded article formed by using the masterbatch.

Hydrogenated nitrile rubber (hereinafter sometimes referred to as 'HNBR') is a rubber that improves heat resistance and weather resistance by adding hydrogen to nitrile rubber (NBR), and is used for automobile belt materials, various oil seals, packings, etc. It is used as.

1,3-bis (tert-butyl peroxy isopropyl) benzene is an organic peroxide mainly used as a crosslinking agent or curing agent for synthetic rubber or synthetic resin. Since these organic peroxides have -O-O- bonds in their molecules, they thermally decompose or react with reducing substances at relatively low temperatures to easily generate free radicals. The generated free radicals cause addition reactions or separation reactions such as hydrogen to unsaturated double bonds to crosslink or cure synthetic rubbers. 1,3-bis (tert-butyl peroxy isopropyl) benzene is also used as a crosslinking agent of HNBR.

Conventionally, in the step (adding and kneading) process of the organic peroxide which is a crosslinking agent of HNBR, the organic peroxide of a single product is entered using a roll, a sealed kneader, etc. However, the kneading operation requires the skill of the operator, takes a very long time to uniformly disperse the organic peroxide, and also the manufacturing problems due to the roll operation, such as the HNBR drop off (not wound) during the kneading operation There was.

Thus, in order to solve the problem of dispersibility of organic peroxides, a masterbatch containing organic peroxides is used. There are already several masterbatches based on 1,3-bis (tert-butyl peroxy isopropyl) benzene on the market, and Nichiyu Co., Ltd. perbutyl P-40 and peroxymon F40 are known. These masterbatches generally use an inert inorganic filler such as calcium carbonate or silica as the diluent.

By using these masterbatches, it is possible to shorten the tapping time in the case of tapping into HNBR by about 15 minutes to about 10 minutes. However, the manufacturing problem of HNBR dropping off the roll during kneading was not improved.

In addition, there is a desire not to blend an inorganic filler such as calcium carbonate as the diluent of the masterbatch. Therefore, when the diluent of the masterbatch was HNBR instead of the inorganic filler, it was found that it was difficult to increase the content of 1,3-bis (tertbutylperoxy isopropyl) benzene in the masterbatch. That is, an attempt was made to mix and disperse 1,3-bis (tert-butyl peroxy isopropyl) benzene in a ratio of 10 to 50% by mass relative to HNBR. However, since compatibility with HNBR is not necessarily high, 1,3-bis (tert-butyl peroxy isopropyl) benzene was easily separated (bloomed) from HNBR, making it difficult to produce sheet dough-like masterbatches.

Patent Literature 1 discloses a masterbatch mainly composed of 1,3-bis (tert-butyl peroxy isopropyl) benzene in which HNBR and a low molecular weight polybutadiene oligomer are used in combination.

1) Japanese Unexamined Patent Publication No. 2008-31334

However, the masterbatch of patent document 1 contains a polybutadiene oligomer as a component, and cannot be made into the HNBR composition which does not contain this oligomer.

This invention is made | formed in view of such a situation. That is, the problem of the present invention is that the organic peroxide for HNBR which can solve the problem in the processing work that the content of 1,3-bis (tert-butyl peroxy isopropyl) benzene is high and HNBR falls off from the roll during kneading operation is solved. To provide a masterbatch. Moreover, it is providing the HNBR composition and HNBR crosslinked molded article which use this masterbatch.

MEANS TO SOLVE THE PROBLEM This inventor examined the composition of HNBR in order to solve the said subject. As a result, compatibility with 1,3-bis (tert-butyl peroxy isopropyl) benzene is achieved by setting the amount of bound acrylonitrile of HNBR (hereinafter sometimes referred to as "bound AN amount") to an appropriate range. Found out it was possible to raise. Moreover, the appropriate composition was also found about the carbon black added as a reinforcing agent. The present invention has been completed based on such knowledge.

That is, the organic peroxide masterbatch for HNBR of the present invention contains HNBR, 1,3-bis (tert-butyl peroxy isopropyl) benzene, and carbon black, and the amount of binding AN of HNBR is less than 25% by mass. Content of 1, 3-bis (tertiary butyl peroxy isopropyl) benzene is 10-30 mass%, and content of the said carbon black is 10-30 mass%.

In addition, the organic peroxide masterbatch for HNBR of the present invention preferably has Mooney viscosity ML _{1 + 4} (100 ° C) of HNBR of 30 to 100.

The organic peroxide masterbatches for the HNBR of the invention is a nitrogen adsorption specific surface area of the carbon black from 20 to 80 m ² / g, preferably in the DBP absorption is 50 to 160 cm ³ / 100g.

In addition, the HNBR composition of the present invention is made by using the organic peroxide masterbatch for HNBR.

The HNBR crosslinked article of the present invention is obtained by crosslinking the HNBR composition.

The organic peroxide masterbatch for HNBR of the present invention has a high content of 1,3-bis (tertiary butyl peroxy isopropyl) benzene, which can solve the problem in the processing work in which HNBR falls off from the roll during kneading.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail. However, the scope of the present invention is not limited to embodiment as a specific example demonstrated below.

The organic peroxide masterbatch for HNBR of this embodiment (Hereinafter, it may be described as "masterbatch") contains HNBR, 1, 3-bis (tertiary butyl peroxy isopropyl) benzene, and carbon black. Hereinafter, each component is demonstrated.

( HNBR )

HNBR is a rubber which improves heat resistance, chemical resistance, weather resistance and the like by hydrogenating unsaturated bonds in the polymer main chain of the nitrile rubber which is an acrylonitrile-butadiene copolymer polymer.

An iodine value (g / 100g) is used as a reference for the amount of unsaturated bonds remaining in the polymer backbone of HNBR. In consideration of heat resistance, the iodine value (g / 100g) is preferably 20 or less, more preferably 15 or less. On the other hand, peroxide crosslinking and special crosslinking (such as amine crosslinking) can be carried out by appropriately remaining unsaturated bonds in HNBR, which is preferable from the viewpoint of improvement of heat resistance, mechanical strength, oil resistance and the like.

HNBR has heat resistance close to acrylic rubber and has excellent chemical stability. Moreover, mechanical strength, abrasion resistance, etc. are also excellent. Therefore, it has suitable properties for applications such as oil seals and packings.

The present inventors paid attention to the amount of binding AN of HNBR in order to increase the compatibility between HNBR and 1,3-bis (tert-butyl peroxy isopropyl) benzene. In general, when the amount of bound AN in HNBR increases, the polarity of HNBR increases and oil resistance, abrasion resistance, and the like of HNBR improve. However, the appropriate amount of binding AN was unclear in relation to 1,3-bis (tert-butyl peroxy isopropyl) benzene. Therefore, as a result of examination, it was found that separation (bloom) does not occur well even when the amount of binding AN of HNBR is less than 25% by mass, even if it contains a high concentration of 1,3-bis (tert-butyl peroxy isopropyl) benzene.

This result was presumed to be because the solubility parameter Sp value of 1, 3-bis (tert-butyl peroxy isopropyl) benzene was in the range close to HNBR of low binding AN amount. Moreover, when the amount of binding AN of HNBR was less than 25 mass%, the contamination in the mixing tank of the kneading apparatus with HNBR was also reduced.

It is preferable that it is 30-100, and, as for the Mooney viscosity ML1 _{+ 4} (100 degreeC) of HNBR, it is more preferable that it is 30-80 from a viewpoint of mechanical strength or workability. A Mooney viscosity ML _{1 + 4} (100 degreeC) is measured based on JISK6300-1: 2013 here.

As the HNBR, for example, a Nippon Xeon company Jetpol (registered trademark), LANXESS manufactured Terban (Therban, registered trademark) and the like can be used.

(1,3- Bis (tertbutyl peroxy isopropyl) benzene )

1,3-bis (tert-butyl peroxy isopropyl) benzene is an organic peroxide also called 1,3-bis [1- (tert-butylperoxy) -1-methylethyl] benzene. It is a white powder, and is a compound of CAS number 25155-25-3.

(Carbon black)

The masterbatch contains carbon black as a reinforcing agent. Examples of the reinforcing agent include silica (white carbon), magnesium carbonate and clay in addition to carbon black, but carbon black is preferable. By selecting the appropriate carbon black, the workability can be further improved.

As carbon black, carbon black whose nitrogen adsorption specific surface area is 20-80 m <^2> / g is preferable, and carbon black whose 30-50 m <^2> / g is more preferable. If the nitrogen adsorption specific surface area of the carbon black is smaller than the above numerical range, the dispersion of the carbon black becomes insufficient, the dough is cured, and roll workability is lowered. On the other hand, when the nitrogen adsorption specific surface area of carbon black is larger than the said numerical range, the green strength of a dough will fall and roll workability will fall. The nitrogen adsorption specific surface area of carbon black can be measured based on JISK6217: 1997.

Moreover, as carbon black, carbon black whose DBP (dibutyl phthalate) absorption amount is 50-160 cm <^3> / 100g is preferable, and carbon black whose 100-150 cm <^3> / 100g is more preferable. The amount of DBP absorption is indicative of the porosity between the aggregates of carbon black. Roll workability becomes it favorable that the DBP absorption amount of carbon black exists in the said numerical range. The DBP absorption amount of carbon black can be measured based on JISK6217: 1997.

(Master batch)

The content of 1,3-bis (tert-butyl peroxy isopropyl) benzene in the masterbatch is 10 to 30 mass%, preferably 20 to 30 mass%. Moreover, content of the carbon black in masterbatch is 10-30 mass%, and 20-30 mass% is preferable. In the masterbatch, components other than 1,3-bis (tert-butyl peroxy isopropyl) benzene and carbon black are basically HNBR. The masterbatch thus contains a high concentration of 1,3-bis (tert-butyl peroxy isopropyl) benzene. If the content of 1,3-bis (tert-butyl peroxy isopropyl) benzene and carbon black is within the above numerical range, there is a problem in processing that HNBR falls off from the roll during the kneading operation due to excellent kneading property and roll workability. Can be solved.

Since versatility is required for masterbatch, additives, such as a processing aid, can be mix | blended as components other than HNBR, 1, 3-bis (tertiary butyl peroxy isopropyl) benzene, and carbon black. These additives are suitably added as needed.

(Manufacturing method of master batch)

As a kneading apparatus used for manufacturing a masterbatch, it is preferable to use a sealed kneading apparatus in order to cut off the influence of air as much as possible. The kneading apparatus may be a batch type or a continuous type. Batch kneading apparatuses include pressurized kneaders, Banbury mixers, open rolls, and the like. Examples of the continuous kneading apparatus include a single screw extruder, a twin screw extruder, a feeder loader and the like.

The masterbatch can be prepared by kneading each component for about 10 minutes using the kneading apparatus. Specifically, after the HNBR polymer was sovietized, a mixture of 1,3-bis (tert-butyl peroxy isopropyl) benzene, carbon black and the like premixed in advance was added in two to three portions, and 10 was added. By kneading for about a minute.

The obtained masterbatch is weighed at a ratio corresponding to the amount of organic peroxide required for crosslinking, and can be obtained as an HNBR composition by mixing with HNBR and other components to perform melt kneading or the like. In addition, the obtained HNBR composition can be formed into a crosslinked molded article by crosslinking molding under the crosslinking conditions of HNBR which are usually performed.

Conventionally, when the low melting point and powder 1,3-bis (tert-butyl peroxy isopropyl) benzene is contacted with HNBR, the roll operation is very long, which causes deterioration of the working environment due to chemical scattering and the problem of HNBR falling off the roll. It was to have. By adopting the masterbatch of the present embodiment, it is possible to drastically shorten the working time without requiring the operator's skill. In addition, the problem of HNBR falling off the roll during kneading was eliminated, and the working environment was improved, and safety work was secured.

Example

Hereinafter, although an Example and a comparative example demonstrate this invention, these Examples do not limit this invention.

Masterbatch Raw Material

Hnbr: jet pole 2000l, 3110, 4310 by Nippon Zeon

HNBR: LANXESS manufactured turban AT LT2004VP

Binding AN amount and Mooney viscosity of each HNBR are shown in Table 1.

1,3-bis (tert-butyl peroxy isopropyl) benzene: percadox 14 manufactured by Kayaku Acquizo

Carbon black: carbon black manufactured by Tokai Carbon Co., Ltd., SRF-HS (Sist SVH), SRF (Sist S), FEF (Sist SO), MAF (Sist 116)

The nitrogen adsorption specific surface area and DBP absorption amount of each carbon black are shown in Table 2.

Silica: Precipitation silica made by Tosoh Silica, Nipsil ER

(Preparation of Masterbatch Composition)

A kneader (a pressurized 3 l kneader manufactured by Nippon Spindle Co., Ltd.) was used as a kneader for producing a master batch.

After sieving the HNBR polymer with the composition shown in Table 3, a mixture of 1,3-bis (tert-butyl peroxy isopropyl) benzene and a premix premixed was added three times, and the mixture was rotated at 30 rpm for 10 minutes. Kneaded.

Each masterbatch composition thus obtained was used to evaluate each of the following items, and the results are shown in Table 3.

( Kneader Kneading )

The evaluation was performed from the following viewpoints about the kneading by kneader and the situation after kneading.

(Circle): There is no problem in particular, and kneading property is favorable

△: low power torque, insufficient dough

X: It is the worst state among x when kneading | mixing is difficult or it cannot be kneaded, especially when it becomes sand-like at the time of kneading discharge and does not stick together as a dough.

(Roll workability)

Each masterbatch composition was kneaded using a 12 inch open roll to evaluate roll workability based on the following criteria. Here, bagging refers to a phenomenon in which dough rolled up on a roll rises from the surface of the roll so that the knife does not enter and sheet feeding cannot be performed.

○: good workability

△: slightly bagged (difficult to wind)

×: bagging is severe (can't be wound)

( Dough  Ease of foundation)

Each masterbatch composition was used to prepare sheet dough 5 mm thick. The prepared sheet dough was left to cool at room temperature for 24 hours, and then cut with scissors.

○: easy cutting

△: slightly hard but can be cut

×: hard to cut

As can be seen from the evaluation results in Table 3, the masterbatch compositions of Examples 1 to 2 had good performances in kneader kneading, roll workability, and ease of dough cutting. In the masterbatch composition of Comparative Example 1, the amount of HNBR bound AN is 25% by mass, so that the dough during kneading becomes insufficient and some bagging occurs during kneading of the kneader. I was a bit behind. In the masterbatch composition of Comparative Example 2, since the amount of binding AN of HNBR was 36% by mass, it did not form a sponge in the kneader discharge and was not wound on a roll, and performance evaluation thereafter could not be performed. The masterbatch composition of Comparative Example 3 had a high carbon black content and a large amount of H in the amount of bound AN of HNBR, resulting in a sponge-like shape at the time of kneader discharge, resulting in inferior performance.

Although the masterbatch composition of Comparative Examples 4-6 differs in the kind of carbon black, since the content of carbon black is large, it was inferior in all the performances of kneader kneading | mixing property, roll workability, and the ease of dough cutting. Although the masterbatch composition of the comparative example 7 used silica as a reinforcing agent, the dough viscosity became very high, the bagging generate | occur | produced at the time of roll kneading | mixing, and the ease of dough cutting was inferior.

The masterbatch composition of the comparative example 8 was inferior in roll workability because there was much content of carbon black. Since the masterbatch composition of the comparative example 9 had a large content of a crosslinking agent, it turned into sand at the time of kneading | discharging a kneader, and it did not aggregate as a dough, and performance evaluation after that could not be performed.

Claims (5)

Hydrogenated nitrile rubber, 1,3-bis (tertbutyl peroxy isopropyl) benzene and carbon black,
The amount of bonded acrylonitrile of the hydrogenated nitrile rubber is less than 25% by mass,
The content of the 1,3-bis (tert-butyl peroxy isopropyl) benzene is 10 to 30% by mass,
An organic peroxide masterbatch for hydrogenated nitrile rubber, wherein the carbon black content is 10 to 30% by mass. The method of claim 1,
An organic peroxide masterbatch for hydrogenated nitrile rubber in which the Mooney viscosity ML _{1 + 4} (100 ° C.) of the hydrogenated nitrile rubber is 30 to 100. The method according to claim 1 or 2,
The carbon black had a specific surface area of nitrogen adsorption of 20 to 80 m ² / g, DBP absorption of hydrogenated nitrile rubbers organic peroxide masterbatches, characterized in that 50 to 160 cm ³ / 100g. Hydrogenated nitrile rubber composition formed using the organic peroxide masterbatch for hydrogenated nitrile rubber in any one of Claims 1-3. The hydrogenated nitrile rubber crosslinked molded article formed by crosslinking the hydrogenated nitrile rubber composition of Claim 4.