KR20230169690A - High-insulation rubber composition containing hydration reagent - Google Patents

Abstract

The present invention relates to a highly insulating rubber composition containing a hydration reactive agent, and to a rubber composition that can maintain uniform high insulating properties by removing moisture remaining in all compounding agents including silica, which impairs insulating performance, through a hydration reaction. It's about.
The present invention provides an insulating rubber composition containing raw rubber, silica, additives, and conductive additives, wherein the rubber composition further includes a hydration reaction agent selected from one or more of cement, plaster, and metal oxide, wherein the hydration reaction agent is rubber. The technical gist is that the withstand voltage of the rubber composition satisfies at least 30,000 V or more by removing moisture contained in the composition and preventing deterioration of insulation performance due to moisture.

Description

Highly insulating rubber composition containing a hydration reactive agent {HIGH-INSULATION RUBBER COMPOSITION CONTAINING HYDRATION REAGENT}

The present invention relates to a highly insulating rubber composition containing a hydration reactive agent, and to a rubber composition that can maintain uniform high insulating properties by removing moisture remaining in all compounding agents, including silica, which impairs insulating performance, through a hydration reaction. It's about.

The insulating member is made of a rubber composition with insulating properties so that it can be used as an accessory for various insulating products to prevent electric shock to workers during activities in various electrical facilities such as electric circuits, electric appliances, substations, etc.

Usually, the rubber composition constituting the insulating rubber member further contains silica to reinforce rigidity, which is disclosed in Patent Document 1 (Highly wear-resistant rubber composition for shoe outsole and method of manufacturing the same, registration number: 10-1662007).

However, silica is a porous material with silanol groups on the surface, so it easily absorbs moisture in the air. For the above reasons, silica contains about 5 to 6% moisture in the dry season and about 7 to 10% moisture in the rainy season, which hinders the insulating rubber member from maintaining uniform insulation properties depending on the atmospheric conditions. there is.

In addition, most compounding agents added to rubber members contain 0.05 to 0.6% moisture, although not as much as silica, and this may also affect the insulating properties of the insulating rubber member.

Due to all compounding agents including silica, which easily absorbs moisture, it is difficult to stably maintain the uniform high insulation properties of the rubber composition, making quality control difficult.

Therefore, there is a need to develop technology for a method to uniformly maintain the high insulation properties of the rubber composition by removing the random moisture content caused by silica and satisfying the withstand voltage characteristics.

Domestic Patent Publication No. 10-1662007, registered on September 27, 2016.

The present invention was invented to solve the above problems. By using a hydration reaction agent such as cement, plaster, or metal oxide, the residual moisture caused by all mixing agents, including silica, is removed through a hydration reaction, thereby satisfying the withstand voltage characteristics. It is a technical problem to provide a highly insulating rubber composition containing a hydration reactive agent that allows.

In order to solve the above technical problem, the present invention provides an insulating rubber composition containing raw rubber, silica, additives, and conductive additives, wherein the rubber composition contains a hydration reactive agent selected from one or more of cement, plaster, and metal oxide. Furthermore, the hydration reactive agent is characterized in that the withstand voltage of the rubber composition satisfies a minimum of 30,000 V or more by removing moisture contained in the rubber composition and preventing deterioration of insulation performance due to the moisture. Provided is a highly insulating rubber composition containing.

In the present invention, the rubber composition is characterized in that it contains 1 to 20 parts by weight of the conductive additive based on 100 parts by weight of the raw rubber.

In the present invention, the conductive additive is characterized by being selected from the group consisting of ketcheon black, acetylene black, and carbon fiber.

In the present invention, the rubber composition is characterized in that it contains 1 to 10 parts by weight of the hydration reactive agent based on 100 parts by weight of the raw rubber.

In the present invention, the metal oxide is characterized in that it is an oxide of one or more metals selected from the group consisting of groups 1 and 2 of the periodic table.

According to the present invention as a means of solving the above problem, a hydration reaction agent is further included in the rubber composition containing a conductive additive and silica to remove moisture contained in the silica so that the withstand voltage of the rubber composition is at least 30,000 V or more. , by stably maintaining the high insulating properties of the insulating rubber composition by using a conductive additive, there is an effect of providing a method for removing moisture from the highly insulating rubber composition.

In the highly insulating rubber composition, which has voltage resistance characteristics through moisture removal, the moisture contained in all mixing agents, including silica, has been removed, making it possible to commercialize the highly insulating rubber composition with uniform insulating performance such as insulating members, making it stable. It has the effect of securing insulation performance.

1 is an exemplary diagram of a withstand voltage characteristic test according to Test Example 1.

Since the present invention can make various changes and take various forms, specific embodiments will be described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of a combination of features, numbers, steps, components, etc. described in the specification, but are not intended to indicate the presence of one or more other features, numbers, or steps. , it should be understood that the existence or addition possibility of combinations of components, etc. is not excluded in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings they have in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an idealized or excessively formal sense. No.

Here, repeated descriptions, known functions that may unnecessarily obscure the gist of the present invention, and detailed descriptions of configurations are omitted. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The present invention relates to a highly insulating rubber composition containing a hydration reactive agent. In the insulating rubber composition containing raw rubber, silica, additives and conductive additives, the rubber composition is a hydration material selected from one or more of cement, plaster, and metal oxide. By further including a reactive agent, the hydration reactive agent removes moisture contained in the rubber composition and prevents deterioration of insulation performance due to moisture, so that the withstand voltage of the rubber composition satisfies at least 30,000 V or more.

The highly insulating rubber composition containing the hydration reactive agent is prepared by kneading raw rubber in a kneader, adding conductive additives, silica, and additives that are not conductive additives (one or more of zinc oxide, stearic acid, and polyethylene glycol). When mixing, a hydration reaction agent is added together to manufacture the compound, then the compound is lowered into a sheet using a twin-screw roll mill and stabilized for 24 hours, and then the compound is added with additional additives (sulfur and vulcanization accelerator) in a twin-screw roll mill. Mix and disperse. In particular, one or more hydration reagents among cement, plaster, and metal oxide absorb and remove moisture contained in silica or moisture contained in components other than silica, thereby obtaining a highly insulating rubber composition that satisfies a withstand voltage of at least 30,000 V or more. Do it as

According to the above-described characteristics, first, the raw rubber is put into the kneader and kneaded, and then the conductive additive, silica, additive, and hydration agent are mixed to prepare a compound (S10).

This is done by pre-injecting the raw rubber into the kneader and mixing it evenly by providing heat for a certain period of time. Pre-kneading the raw rubber in the kneader makes it easier to disperse and mix the conductive additives, silica, additives, and hydration reagents added later. can do.

In detail, after preheating the kneader to 100 to 120°C, raw rubber is added and pre-kneaded at 10 to 50 rpm for 30 seconds to 3 minutes at a temperature of 80 to 160°C to soften the raw rubber. If the preheating condition is less than 100°C, a lot of time may be consumed in kneading the raw rubber, and if the preheating temperature exceeds 120°C, it may cause process degradation, which is not desirable. Subsequently, in order to knead the raw rubber in a preheated kneader, if the temperature is less than 80 ℃, it is lower than the minimum preheated temperature and it is impossible to increase the kneading properties of the raw rubber. Even if it is less than 30 seconds, it causes a decrease in the kneading properties of the raw rubber, whereas 160 ℃ If it exceeds or exceeds 3 minutes, the physical properties of the raw rubber may be impaired, which may cause problems such that it cannot sufficiently serve as a base material for the rubber composition.

The raw rubber is a rubber that serves as a base for a highly insulating rubber composition, and high-temperature and high-pressure vulcanized rubbers can be used. The raw rubber may be one or more of natural rubber (NR) and synthetic rubber (SR). Synthetic rubber includes butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), and ethylene propylene diene monomer rubber (EPDM). It may be one or more selected from the group consisting of.

The conductive additive may be, for example, one or more of conductive carbon black, Ketjen black and Acetylene black. Ketham Black is a carbon black with excellent conductivity. It is strong against external forces and has the advantage that its original level of conductivity does not decrease even when mixed with other ingredients (e.g. raw rubber, etc.). Acetylene black is a type of carbon black. It is manufactured by thermally decomposing high-purity acetylene gas under conditions without oxygen supply to form colloidal-sized particles. Compared to other carbon blacks, it has fewer impurities and has higher crystallinity.

Additionally, the conductive additive may be carbon fiber made of a carbon-based material. Carbon fiber is a long-fiber carbon material with a mass content of carbon elements of 90% by weight or more, and is a fiber that combines the characteristics of the carbon material and the characteristics of the fiber form. Carbon fiber has excellent characteristics such as heat resistance, chemical stability, thermal/electrical conductivity, dimensional stability due to low thermal expansion, low density, friction and wear characteristics, X-ray transparency, electromagnetic wave shielding, biocompatibility and flexibility, and activation. Depending on the conditions, it is possible to provide significantly superior adsorption properties. These carbon fibers depend on the crystallinity of electrical conductivity and can be said to be a conductor with an electrical resistance value of 0.5 to 0.8 × 10 ^-3 Ω·cm.

By mixing 1 to 20 parts by weight of the conductive additive with 100 parts by weight of raw rubber that has been pre-kneaded in a kneader, the desired level of hardness and insulation can be secured while maintaining a high tensile strength of the highly insulating rubber composition. When the conductive filler is mixed in an amount of less than 1 part by weight, the tensile strength and elongation can be maintained high, but there is a problem in that the hardness and insulation required for the insulating member are reduced. Conversely, if the conductive additive exceeds 20 parts by weight, the tensile strength and elongation are significantly lowered, the density and hardness increase more than necessary, and when applied to an insulating product, electricity can conduct relatively well, so the effect of preventing high voltage is not expressed. can not do it.

It is preferable that the average particle size of ketium black and acetylene black, which can be used as a conductive additive, is 34 to 48 nm, and the average length of carbon fiber is 1 mm or less. Through this, the dispersibility of the conductive additive into the raw rubber in the kneader can be improved.

Silica is added to the highly insulating rubber composition to reinforce rigidity. Silica has the effect of improving cutting properties, chipping properties, tearing resistance, and wear resistance, and can improve the mechanical strength of a highly insulating rubber composition.

That is, considering that mixing only the conductive additive into the raw rubber will result in uneven dispersion of the conductive additive, by using it in combination with silica, the dispersibility of the conductive additive within the rubber composition can be further increased, while mechanical strength can be imparted by the silica itself. There will be.

For this purpose, the content of silica may be 10 to 50 parts by weight, more preferably 25 to 35 parts by weight, based on 100 parts by weight of raw rubber. If less than 25 parts by weight of silica is mixed with 100 parts by weight of raw rubber, it will only have a minor effect on improving the mechanical strength of the highly insulating rubber composition. If it exceeds 35 parts by weight, the amount of silica, which is sensitive to moisture, will increase, preventing uniform moisture removal. There are difficulties in this, making it impossible to satisfy the withstand voltage characteristics of 30,000 V or more.

Afterwards, additional additives can be added to the kneader. The additive may be one or more from the group consisting of zinc oxide, stearic acid, and polyethylene glycol.

Zinc oxide can improve heat resistance and vulcanization speed, stearic acid can improve the dispersibility and processability of additives, and polyethylene glycol is coated on silica, preventing vulcanization through unnecessary combination of silica and vulcanization accelerator. Prevent time from extending.

In detail, since numerous silanol groups exist on the surface of silica, the interaction between the silicas forming the aggregate is very strong, so it may not be easily dispersed in non-polar raw rubber. In addition, the silanol group on the surface of silica adsorbs them by hydrogen bonding with polar organic substances present in the rubber composition. In particular, most vulcanization accelerators used in rubber compositions contain an amine group as a functional group, so the silanol group of silica has a strong hydrogen bond. It forms bonds and is well adsorbed to the surface. Accordingly, the vulcanization time is extended due to unnecessary combination of silica and vulcanization accelerator, which can be suppressed by adding polyethylene glycol.

The above additives may be included in an amount of 5 to 15 parts by weight based on 100 parts by weight of raw rubber. Preferably, it may contain 1 to 10 parts by weight of zinc oxide, 0.1 to 2 parts by weight of stearic acid, and 0.5 to 3 parts by weight of polyethylene glycol, based on 100 parts by weight of raw rubber, and more preferably, zinc oxide based on 100 parts by weight of raw rubber. It may be included in the range of 4 to 6 parts by weight, 0.5 to 1.5 parts by weight of stearic acid, and 1 to 2 parts by weight of polyethylene glycol. Through these additives, the crosslinking reaction of the rubber composition can be maintained at an appropriate rate, thereby improving productivity. If the additive is mixed beyond the above range, unreacted substances are exposed to the surface of the specimen, causing a blooming phenomenon.

In particular, a hydration agent can be added to remove moisture contained in silica. The hydration reactive agent hydrates the remaining moisture in the silica and reduces the moisture content of the silica so that the withstand voltage satisfies at least 30,000 V, so that when a voltage of 30,000 V is applied to the highly insulating rubber composition, it lasts for at least 60 seconds. It can stably maintain the high insulation properties of the rubber composition while having durable withstand voltage characteristics.

In order to maintain the high insulation properties of the rubber composition, the hydration agent that controls the moisture of the silica to increase the withstand voltage to at least 30,000 V may be one or more of cement, calcined gypsum (CaSO ₄ ·1/2H ₂ O, calcined gypsum), and metal oxide. You can.

Cement is composed of calcium oxide (CaO) as its main ingredient, and when it comes in contact with the moisture of silica, a chemical reaction occurs and the moisture of silica can be removed through hydration, which causes solidification and hardening. In other words, the hydration reaction is a process in which the four major clinker compounds in cement chemically react with moisture (H ₂ O) in silica to produce hydrates: Alite, Belite, Aluminate, and Ferrite. The hydration reaction of (ferrite) is shown in Scheme 1, Scheme 2, Scheme 3, and Scheme 4 below.

[Scheme 1]

C ₃ S + H ₂ O → 3CaO·2SiO ₂ ·3H ₂ O + Ca(OH) ₂ (about 45% of the content of C ₃ S)

[Scheme 2]

C ₂ S + H ₂ O → 3CaO·2SiO ₂ ·3H ₂ O + Ca(OH) ₂ (about 25% of the content of C ₂ S)

[Scheme 3]

C ₃ A + H ₂ O → 3CaO·Al ₂ O ₃ ·3H ₂ O → 4CaO·Al ₂ O ₃ ·14H ₂ O + Ca(OH) ₂ → 3CaO·Al ₂ O ₃ ·6H ₂ O

[Scheme 4]

C ₄ AF + H ₂ O → 3CaO·Al ₂ O ₃ ·6H ₂ O + 3CaO·Fe ₂ O ₃ ·6H ₂ O

However, in Schemes 1 to 4, C means CaO, S means SiO ₂ , A means Al ₂ O ₃ , and F means Fe ₂ O ₃ , for example, C ₃ A means 3CaO·Al ₂ O ₃ it means.

Here, taking Reaction Formulas 1 and 2 as an example, when moisture of silica is added to cement, calcium silicate-based compounds such as alite and belite react with moisture (H ₂ O) of silica to form calcium silicate hydrate, thereby carrying out the solidification and hardening process. Through this process, the strength can be expressed in the highly insulating rubber composition. In the process of producing calcium silicate hydrate, calcium hydroxide is produced and dissolved in moisture. The calcium hydroxide reacts with other components of cement to form hydrate and hardens, playing an important role in developing the strength of the highly insulating rubber composition. . In this way, the cement provides strength to the rubber composition, so that when a voltage of 30,000 V is applied, it can withstand at least 60 seconds without being destroyed, thereby enabling it to have withstand voltage characteristics.

Before explaining calcined gypsum, gypsum is made up of calcium sulfate (CaSO ₄ ) as its main ingredient and is produced as a hardened mineral by combining with water in the natural state. The gypsum produced in this way is heated to a temperature of 100 ℃ or higher to remove moisture. As it escapes, it becomes white powder, and this gypsum powder is called baked gypsum or plaster.

[Scheme 5]

CaSO ₄ ·1/2H ₂ O + 3/2H ₂ O → CaSO ₄ ·2H ₂ O

Metal oxides may be oxides of one or more metals selected from the group consisting of groups 1 and 2 of the periodic table, where metals of group 1 or 2 react with moisture (H ₂ O) of silica and hydrate like cement or plaster. By causing a reaction, it is possible to control the silica moisture content of the highly insulating rubber composition.

Group 1 metals may be alkali metals such as lithium (Li), sodium (Na), or potassium (K), and these oxides may be lithium oxide (Li ₂ O), sodium oxide (Na ₂ O), or potassium oxide ( K ₂ O) can be. Lithium oxide, sodium oxide, and potassium oxide react with moisture (H ₂ O) in silica to form hydroxides as shown in Scheme 6, Scheme 7, and Scheme 8 below.

[Scheme 6]

Li ₂ O (s) + H ₂ O (l) → 2LiOH

[Scheme 7]

Na ₂ O (s) + H ₂ O (l) → 2NaOH

[Scheme 8]

K ₂ O (s) + H ₂ O (l) → 2KOH

Group 2 metals may be alkaline earth metals such as magnesium (Mg), calcium (Ca), or barium (Ba), and these oxides may include magnesium oxide (MgO), calcium oxide (CaO), or barium oxide (BaO). It can be. Magnesium oxide and barium oxide react with moisture (H ₂ O) in silica to form hydroxide as shown in Scheme 9 and Scheme 10 below.

[Scheme 9]

MgO (s) + H ₂ O (l) → Mg(OH) ₂

[Scheme 10]

BaO (s) + H ₂ O (l) → Ba(OH) ₂

In addition, for example, calcium oxide is a white crystalline material in the form of an equiaxed crystal system in which three virtual axes passing through the center of the crystal are orthogonal to each other and have the same length. It absorbs moisture from silica and decomposes into calcium hydroxide. In other words, calcium oxide reacts with the moisture of silica as shown in Scheme 11 below, producing calcium hydroxide (slaked lime) along with an exothermic reaction, suppressing the production of moisture in silica and maintaining high insulation properties of the rubber composition by maintaining a withstand voltage of at least 30,000 V or more. there is.

[Scheme 11]

CaO (s) + H ₂ O (l) → Ca(OH) ₂

The above hydration reactive agent can be mixed in an amount of 1 to 10 parts by weight based on 100 parts by weight of raw rubber. If mixed in less than 1 part by weight, the random amount of moisture contained in the silica cannot be sufficiently removed, resulting in poor withstand voltage characteristics. If mixed in more than 10 parts by weight, it may act as a foreign substance in the rubber composition, so mix in less than 10 parts by weight. It is desirable to add

Next, the compound is put into a roll mill and stabilized (S20).

The stabilization process is carried out to ensure the chemical reaction stability of raw rubber, conductive additives, silica, additives, and hydration agents. That is, in order to form a sheet using the previously prepared rubber composition, it is formed into a sheet using a twin-screw roll mill and then undergoes a sufficient stabilization process for 20 to 30 hours to later use a vulcanizing agent using the residual heat remaining inside the twin-screw roll mill. When added, it prevents the vulcanizing agent from reacting with the raw rubber and also prevents the specimen from being distorted or damaged.

If the stabilization process is less than 20 hours, it is not enough time to induce reaction stability between the raw rubber, conductive additives, silica, additives, and hydration reagents. If it exceeds 30 hours, the physical properties are affected compared to the case where the stabilization time is less than that. There is no significant difference, so it is time-consuming.

Finally, the stabilized compound is introduced into a roll mill and the vulcanizing agent and vulcanization accelerator are mixed and dispersed (S30).

As additional additives, vulcanizing agents and vulcanization accelerators may be further included. The vulcanizing agent contains sulfur that can vulcanize a highly insulating rubber composition, thereby reducing the gap between rubber molecular chains and increasing crosslinking density. The vulcanizing agent may be included in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of raw rubber. If it is mixed in less than 0.1 parts by weight, a lot of time is consumed until vulcanization of the rubber composition begins and the crosslinking density is also poor, and if mixed in an amount of less than 0.1 parts by weight, the vulcanizing agent may be mixed in an amount of more than 2 parts by weight. Otherwise, an over-crosslinking reaction may occur in the rubber composition, which is not desirable.

The vulcanization accelerator increases the vulcanization speed when manufacturing a highly insulating rubber composition, shortens the crosslinking time, lowers the crosslinking temperature, and reduces the amount of vulcanizing agent used. This vulcanization accelerator may be included in an amount of 1 to 3 parts by weight based on 100 parts by weight of raw rubber in a roll mill.

If the vulcanization accelerator is added in an amount of less than 1 part by weight based on 100 parts by weight of raw rubber, vulcanization takes a long time and productivity decreases. On the other hand, if the vulcanization accelerator exceeds 3 parts by weight per 100 parts by weight of raw rubber, blooming phenomenon occurs on the surface of the specimen and the scorch time is shortened.

Vulcanization accelerators include thiazole series such as 2-Mercapto benzo thiazole and dibenzothiazyl disulfide, tetramethylthiuram disulfide, and tetramethylthiuram. It may be any one or more selected from the group consisting of Thiuram series such as monosulfide (Tetramethylthiuram monosulfide), Zinc dibutyldithiocarbamate, and Dithiocarbamate series such as Zinc diethyldithiocarbamate.

Instead of including a conductive additive and silica in the rubber composition of the present invention to have high insulation properties, the moisture problem caused by silica can be controlled to satisfy the withstand voltage characteristics, so the high-insulation rubber composition has high-voltage insulation properties. It has excellent advantages. Accordingly, it can be said that when a voltage of 30,000 V is applied to the highly insulating rubber composition of the present invention, it can withstand the range of 60 to 300 seconds and has excellent withstand voltage characteristics.

Hereinafter, embodiments of the present invention will be described in more detail as follows. However, the following examples are merely illustrative to aid understanding of the present invention and are not intended to limit the scope of the present invention.

<Example 1>

1-1. Manufacturing of compounds (process on the kneader)

Add 100 parts by weight of NBR to a kneader preheated to 100 to 120°C and knead for 1 minute at a speed of 30 rpm, add 10 parts by weight of carbon fiber and 30 parts by weight of silica, mix for 3 minutes, and then add 5 parts by weight of zinc oxide. , 1 part by weight of stearic acid, 1.5 parts by weight of polyethylene glycol, and 1 part by weight of magnesium oxide as a hydration agent were added and mixed for 10 minutes to prepare a compound.

1-2. Production of highly insulating rubber compositions (process on a twin-screw roll mill)

The compound was lowered into a sheet using a twin-screw roll mill and stabilized for 24 hours. Then, 1.2 parts by weight of sulfur and 1 part by weight of vulcanization accelerators M, 1 part of DM, and 0.1 part by weight of TT were added to the compound and dispersed for about 5 minutes. and mixed to prepare a highly insulating rubber composition.

1-3. Manufacture of sheets (process on press)

In order to prepare the high-insulating rubber composition as a specimen, the high-insulating rubber composition was manufactured into a sheet with a thickness of 3 to 4 mm, and was placed in a mold of 22 × 22 × 0.2 cm (width × length × thickness) at a temperature of 155 ° C. and a weight of 130 kg / A flat rubber sheet was completed by press molding at a pressure of cm ² .

<Example 2>

2-1. Manufacturing of compounds (process on the kneader)

Add 100 parts by weight of NBR to a kneader preheated to 100 to 120°C and knead for 1 minute at a speed of 30 rpm, add 10 parts by weight of carbon fiber and 30 parts by weight of silica, mix for 3 minutes, and then add 5 parts by weight of zinc oxide. , 1 part by weight of stearic acid, 1.5 parts by weight of polyethylene glycol, and 5 parts by weight of magnesium oxide as a hydration agent were added and mixed for 10 minutes to prepare a compound.

2-2. Production of highly insulating rubber compositions (process on a twin-screw roll mill)

The compound was lowered into a sheet using a twin-screw roll mill and stabilized for 24 hours. Then, 1.2 parts by weight of sulfur and 1 part by weight of vulcanization accelerators M, 1 part of DM, and 0.1 part by weight of TT were added to the compound and dispersed for about 5 minutes. and mixed to prepare a highly insulating rubber composition.

2-3. Manufacture of sheets (process on press)

In order to prepare the high-insulating rubber composition as a specimen, the high-insulating rubber composition was manufactured into a sheet with a thickness of 3 to 4 mm, and was placed in a mold of 22 × 22 × 0.2 cm (width × length × thickness) at a temperature of 155 ° C. and a weight of 130 kg / A flat rubber sheet was completed by press molding at a pressure of cm ² .

<Example 3>

3-1. Manufacturing of compounds (process on the kneader)

Add 100 parts by weight of NBR to a kneader preheated to 100 to 120°C and knead for 1 minute at a speed of 30 rpm, add 10 parts by weight of carbon fiber and 30 parts by weight of silica, mix for 3 minutes, and then add 5 parts by weight of zinc oxide. , 1 part by weight of stearic acid, 1.5 parts by weight of polyethylene glycol, and 10 parts by weight of magnesium oxide as a hydration agent were added and mixed for 10 minutes to prepare a compound.

3-2. Production of highly insulating rubber compositions (process on a twin-screw roll mill)

The compound was lowered into a sheet using a twin-screw roll mill and stabilized for 24 hours. Then, 1.2 parts by weight of sulfur and 1 part by weight of vulcanization accelerators M, 1 part of DM, and 0.1 part by weight of TT were added to the compound and dispersed for about 5 minutes. and mixed to prepare a highly insulating rubber composition.

3-3. Manufacture of sheets (process on press)

In order to prepare the high-insulating rubber composition as a specimen, the high-insulating rubber composition was manufactured into a sheet with a thickness of 3 to 4 mm, and was placed in a mold of 22 × 22 × 0.2 cm (width × length × thickness) at a temperature of 155 ° C. and a weight of 130 kg / A flat rubber sheet was completed by press molding at a pressure of cm ² .

<Example 4>

4-1. Manufacturing of compounds (process on the kneader)

Add 100 parts by weight of NBR to a kneader preheated to 100 to 120°C and knead for 1 minute at a speed of 30 rpm, add 10 parts by weight of carbon fiber and 30 parts by weight of silica, mix for 3 minutes, and then add 5 parts by weight of zinc oxide. , 1 part by weight of stearic acid, 1.5 parts by weight of polyethylene glycol, and 10 parts by weight of calcium oxide as a hydration agent were added and mixed for 10 minutes to prepare a compound.

4-2. Production of highly insulating rubber compositions (process on a twin-screw roll mill)

The compound was lowered into a sheet using a twin-screw roll mill and stabilized for 24 hours. Then, 1.2 parts by weight of sulfur and 1 part by weight of vulcanization accelerators M, 1 part of DM, and 0.1 part by weight of TT were added to the compound and dispersed for about 5 minutes. and mixed to prepare a highly insulating rubber composition.

4-3. Manufacture of sheets (process on press)

In order to prepare the high-insulating rubber composition as a specimen, the high-insulating rubber composition was manufactured into a sheet with a thickness of 3 to 4 mm, and was placed in a mold of 22 × 22 × 0.2 cm (width × length × thickness) at a temperature of 155 ° C. and a weight of 130 kg / A flat rubber sheet was completed by press molding at a pressure of cm ² .

<Example 5>

5-1. Manufacturing of compounds (process on the kneader)

Add 100 parts by weight of NBR to a kneader preheated to 100 to 120°C and knead for 1 minute at a speed of 30 rpm, add 10 parts by weight of acetylene black and 30 parts by weight of silica, mix for 3 minutes, and then add 5 parts by weight of zinc oxide. , 1 part by weight of stearic acid, 1.5 parts by weight of polyethylene glycol, and 10 parts by weight of calcined gypsum as a hydration agent were added and mixed for 10 minutes to prepare a compound.

5-2. Production of highly insulating rubber compositions (process on a twin-screw roll mill)

The compound was lowered into a sheet using a twin-screw roll mill and stabilized for 24 hours, and then 1.2 parts by weight of sulfur and 1 part by weight of vulcanization accelerators M, 1 part of DM, and 0.1 part by weight of TT were added and dispersed for 5 minutes. and mixed to prepare a highly insulating rubber composition.

5-3. Manufacture of sheets (process on press)

In order to prepare the high-insulating rubber composition as a specimen, the high-insulating rubber composition was manufactured into a sheet with a thickness of 3 to 4 mm, and was placed in a mold of 22 × 22 × 0.2 cm (width × length × thickness) at a temperature of 155 ° C. and a weight of 130 kg / A flat rubber sheet was completed by press molding at a pressure of cm ² .

<Comparative Example 1>

In Comparative Example 1, the same procedure as Example 1 was performed, but unlike Examples 1 to 5, a rubber composition without the addition of a hydration agent was prepared, and a sheet serving as a specimen was manufactured.

The components and contents according to Examples 1 to 5 and Comparative Example 1 are shown in Table 1 below. However, the unit is parts by weight.

Example Comparative example One 2 3 4 5 One NBR 100 100 100 100 100 100 zinc oxide 5 5 5 5 5 5 stearic acid One One One One One One polyethylene glycol 1.5 1.5 1.5 1.5 1.5 1.5 Carbon fiber ¹⁾
(1mm or less) 10 10 10 10 0 10 Acetylene Black 0 0 0 0 10 0 silica ²⁾ 30 30 30 30 30 30 number
fury
half
huh
my MgO One 5 10 0 0 0 CaO 0 0 0 10 0 0 Plaster 0 0 0 0 10 0 M ³⁾ One One One One One One DM ⁴⁾ One One One One One One TT ⁵⁾ 0.1 0.1 0.1 0.1 0.1 0.1 sulfur 1.2 1.2 1.2 1.2 1.2 1.2 1) Xenomaterial Carbon
2) Zeosil-175, specific surface area 160 to 190 m ² /g
3) 2-mercapto benzothiazole
4) Dibenzothiazyl disulfide
5) Tetramethylthiuram disulfide

<Test Example 1>

In this test example, the 2 ± 0.1 mm flat rubber specimens manufactured by the method of Examples 1 to 5 and Comparative Example 1 were evaluated to see how high a voltage they could withstand being applied between two conductors that were not in electrical contact. We analyzed the withstand voltage characteristics.

Prior to analysis, withstand voltage is the limit of applied voltage that can be withstood without being destroyed when the specified alternating voltage is applied to the insulating material to be tested for 1 minute. This is the applied voltage that can be used without fear of destruction of the insulating part of the machine or part. This means the limit of the size of . For the relevant evaluation methods, the dislocation hardness (e.g. expressed in V/mm) specified in the quality standard is multiplied by the specimen thickness (e.g. mm) and the test is performed according to the molded material, laminated rod or laminated plate. It is determined by method or conditions.

Figure 1 is an example of a withstand voltage characteristic test according to Test Example 1 for evaluating dielectric breakdown strength. Electrodes were placed on both sides of a 50 × 50 mm specimen in KS C 2301 Type 1 No. 2 insulating oil according to KS C IEC 60243-1 standard. By connecting, the voltage was raised at a rate of 2,000 V/s, and when the applied voltage reached 30,000 V, the voltage was maintained without further increase and the time at which the specimen was destroyed was measured and confirmed. A total of 5 tests were performed per specimen, and the measured results are listed in Tables 2 to 7 below.

Example 1 Primary Secondary 3rd Withstand voltage After reaching 30,000 V,
time to be destroyed
(candle) 67 65 74 74 62 63 62 69 78 65 74 82 81 73 68

Example 2 Primary Secondary 3rd Withstand voltage After reaching 30,000 V,
time to be destroyed
(candle) 95 81 95 102 90 69 125 96 77 100 69 84 76 94 89

Example 3 Primary Secondary 3rd Withstand voltage After reaching 30,000 V,
time to be destroyed
(candle) 201 176 167 184 215 193 188 237 242 211 194 207 154 142 183

Example 4 Primary Secondary 3rd Withstand voltage After reaching 30,000 V,
time to be destroyed
(candle) 106 75 73 118 107 94 84 134 107 121 86 112 95 114 99

Example 5 Primary Secondary 3rd Withstand voltage After reaching 30,000 V,
time to be destroyed
(candle) 86 135 114 97 117 76 127 98 105 140 83 93 119 104 127

Comparative Example 1 Primary Secondary 3rd 4th 5th Withstand voltage After reaching 30,000 V,
time to be destroyed
(candle) 54 28 64 48 0 167 13 100 31 12 19 43 80 28 5 48 0 41 29 12 68 3 57 27 8

The withstand voltage characteristics of the present invention mean that the specimen must withstand at least 1 minute (60 seconds) after reaching 30,000 V to maintain high insulation properties. In relation to this, insulating products are sometimes established with a withstand voltage characteristic of 14,000 V as a standard, but as the industry becomes more sophisticated, the demand for insulation characteristics requiring a withstand voltage of 30,000 V, which is not standardized in Korea, is increasing.

According to the results in Tables 2 to 6, in the case of Examples 1 to 5, when a voltage of 30,000 V was applied, it had excellent withstand voltage characteristics by withstanding a minimum of 62 seconds and a maximum of 242 seconds, and the moisture caused by silica was removed, making it conductive. It was confirmed that the high insulating properties of the insulating rubber composition were stably maintained by the additives.

Unlike Examples 1 to 5, in Comparative Example 1 in which no hydration agent was mixed, 0 seconds were recorded in the 2nd and 5th rounds, which means that the specimen was destroyed as soon as the voltage reached 30,000 V. In addition, in cases where the destruction time after the voltage reaches 30,000 V is not at least 60 seconds, such as withstanding 19 seconds in the first test of Comparative Example 1, 3 seconds in the second test, and 41 seconds in the third test, Also, the time range was not uniform and a random phenomenon was observed. This is because there is no means to remove moisture from silica, so the withstand voltage characteristic range is random, which prevents it from achieving uniform high insulation properties.

In summary, the present invention prepares a compound through mixing conductive additives, silica, additives, and hydration reagents in a state where raw rubber is put into a kneader and kneaded to remove the moisture content of silica, thereby forming a rubber composition by the conductive additive. It has the characteristic of stably maintaining high insulation properties without being affected by the random moisture content of silica.

According to these characteristics, it is possible to commercialize a highly insulating rubber composition from which moisture has been removed using cement, plaster, or metal oxide, thereby stably securing insulating performance, which has the advantage of being used as an accessory for insulating products.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications and variations will be possible to those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are for explanation, and the scope of the technical idea of the present invention is not limited by these examples. The scope of protection of the present invention should be interpreted in accordance with the scope of the patent claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the present invention.

Claims (5)

In the insulating rubber composition comprising raw rubber, silica, additives and conductive additives,
The rubber composition further includes a hydration agent selected from one or more of cement, plaster, and metal oxide,
The hydration reactive agent is characterized in that the withstand voltage of the rubber composition satisfies a minimum of 30,000 V or more by removing moisture contained in the rubber composition and preventing deterioration of insulation performance due to the moisture. Insulating rubber composition. According to claim 1,
The rubber composition is a highly insulating rubber composition containing a hydration reaction agent, characterized in that it contains 1 to 20 parts by weight of the conductive additive based on 100 parts by weight of the raw rubber. According to claim 1,
A highly insulating rubber composition containing a hydration reactive agent, wherein the conductive additive is one or more selected from the group consisting of ketium black, acetylene black, and carbon fiber. According to claim 1,
The rubber composition is a highly insulating rubber composition containing a hydration reactive agent, characterized in that it contains 1 to 10 parts by weight of the hydration reactive agent based on 100 parts by weight of the raw rubber. According to claim 1,
A highly insulating rubber composition containing a hydration reaction agent, characterized in that the metal oxide is an oxide of one or more metals selected from the group consisting of groups 1 and 2 of the periodic table.