KR100536120B1 - Preparatoin method of liquid silicone rubber forming material with good insulation-breakdown and adhesion properties - Google Patents

Abstract

In the present invention, in the manufacturing method of the rubber molding using the insulation-semiconductor two-component addition liquid silicone rubber material, after the main cross-linking reaction of the insulating material and the semi-conductive material, the insulating comprising a step of inducing the interface adhesion The present invention relates to a method for producing a liquid silicone rubber molded article having excellent fracture strength and adhesive properties. The additional crosslinking reaction is preferably made at a temperature of 0.5 hours to 24 hours at a temperature of 100 ° C to 220 ° C, and more preferably at a temperature of 1 hour to 6 hours at a temperature of 150 ° C to 180 ° C. According to the manufacturing method of the liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties of the present invention, it is possible to improve the adhesiveness of the additional liquid silicone rubber material and thereby to enhance the interfacial properties to achieve excellent electrical insulating properties.

Description

Method for manufacturing liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties {PREPARATOIN METHOD OF LIQUID SILICONE RUBBER FORMING MATERIAL WITH GOOD INSULATION-BREAKDOWN AND ADHESION PROPERTIES}

The present invention relates to a method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties.

In case of junction box, semi-conductive material is used to alleviate electric field in middle part of conductor and insulator. Insulator and semiconductor are generally chemically and physically bonded to provide the desired level of breakdown performance.

Conventionally, epoxy is mainly used as a material for a junction box, particularly an ultra high voltage cable, but has a disadvantage in that a complicated mechanical structure design is required in consideration of an externally given impact or stress.

In addition, a junction box using EPDM rubber was developed as a more flexible material. EPDM is a rubber polymer in which ethylene, propylene, and diene are copolymerized. Although there is no insulation, the aging performance of EPDM materials deteriorates in long-term operation, and thus a more reliable application of the material is required.

Therefore, silicone rubber is used as a rubber material having better aging properties and durability than the EPDM material. Among them, liquid silicone rubber is generally suitable for use as an electric material for ultra-high pressure, in particular electrical insulation, in particular, breakdown strength. In addition, since the material exhibits the viscoelastic behavior of the rubber elastic body, there is an advantage that it is easy to apply to the connection portion or the branch portion of the ultra-high voltage cable.

These liquid silicone materials can be classified into two types. First, an addition type of a condensation type liquid silicone in which a crosslinking reaction proceeds by a condensation reaction of polyvinylsiloxane and a special rare metal such as platinum act as a catalyst for the crosslinking reaction. It can be divided into liquid silicone.

However, in the case of the double condensation type silicone rubber, the reaction by-product is formed after the curing reaction. On the other hand, in the case of the addition liquid silicone, reaction by-products are not produced, and due to a property in which a crosslinking reaction occurs instantaneously at a specific temperature or more, it is known as a material exhibiting excellent electrical insulation properties compared to the condensation type.

Such additional liquid silicone may be classified into a room temperature crosslinking type and a high temperature crosslinking type in which a crosslinking reaction proceeds at a temperature of generally 100 ° C. or more according to the crosslinking initiation temperature.

On the other hand, as a method of manufacturing a combination of a conventional insulator and a semiconductor, there has been the following method.

First, there was a method of using a coupling agent designed to enable special chemical crosslinking as a primer of an insulating-semiconducting liquid silicon interface to show strong adhesion between two interfaces.

However, in the above method, when the electric field is applied, the coupling agent acts as a kind of foreign material, and thus, it is impossible to realize desirable dielectric breakdown characteristics. Especially, when a high electric field is applied, it is used as an ultra high pressure material that requires high electrical insulation such as dielectric breakdown strength. There was a problem that the application is practically difficult.

Second, there was a method of manufacturing a silicone molding to have a desired physical and electrical properties by a suitable method through a cross-linking mechanism containing platinum at room temperature curing liquid silicone or high temperature curing liquid silicone.

That is, for example, crosslinking is carried out by using a catalyst containing platinum to the main compound capable of hydrosilylation reaction and the compound bound to the crosslinking agent component polydimethyl siloxane, using a catalyst containing platinum, which inhibits the platinum catalyst (inhibitor). The curing reaction occurred at a temperature above the decomposition temperature.

Alternatively, a method of forming a combination of two types of insulator liquid silicon material exhibiting excellent electrical insulation properties and semiconducting liquid silicon having a low electrical insulation property to allow electricity to flow by adding a certain amount of conductive carbon black thereto has been known.

However, the above method is a method of forming an additive liquid silicone compound under only main crosslinking conditions. In the case of forming a molded article using only main crosslinking as described above, general material properties may be satisfied, but sufficient adhesive strength and accompanying dielectric breakdown properties may be exhibited. There was a problem of lack.

Therefore, the present invention has been made to solve the above problems,

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a rubber molding using an insulating-semiconductor two-component addition liquid silicone rubber material. It is to provide a method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties.

The object of the present invention is a method for producing a rubber molding using an insulating-semiconductor two-component addition liquid silicone rubber material, the step of inducing the interfacial adhesion through an additional crosslinking reaction after the main crosslinking reaction of the insulating material and the semiconductive material It can be achieved through a method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties.

And the additional crosslinking reaction is preferably made for 0.5 hours to 24 hours at a temperature of 100 ℃ ~ 220 ℃, more preferably for 1 hour to 6 hours at a temperature of 150 ℃ ~ 180 ℃.

Hereinafter, a method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties will be described in detail.

The method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties according to the present invention has excellent adhesion and electrical breakdown strength through a method of improving interfacial adhesion according to the appropriate crosslinking process conditions of main crosslinking and additional crosslinking. To do that.

That is, the method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties according to the present invention is a molding condition (temperature, time) which is generally recommended by a liquid silicone manufacturer. Main crosslinking is carried out through physical contact, and then further crosslinking is performed.

Liquid-silicon materials (liquid-silicon insulating material and liquid-silicon semiconducting material) having different interfaces of insulation and semiconducting, and in one preferred embodiment, room temperature crosslinking by a hydro-silylation reaction through a platinum catalyst Liquid silicone (hereinafter referred to as RTV) or high temperature crosslinked liquid silicone (hereinafter referred to as LSR) is used. Such RTV and LSR are classified according to the crosslinking temperature and the like, and commercially available products well known to those skilled in the art may be used.

More preferably, an insulating material uses an insulating RTV having a viscosity of 5,000 to 50,000 cps or an insulating LSR having a viscosity of 50,000 to 1,500,000 cps, and a semiconducting material having a viscosity of 500,000 to 4,000,000 cps for a semiconducting material. Use LSRs.

By adopting an insulating or semiconducting material within the above viscosity range, not only the ease of performing the process can be achieved, but also as shown in the following examples, further crosslinking process conditions (temperature and time) according to the embodiment of the present invention. ), The effect of improving the adhesive strength and dielectric breakdown properties is excellent.

In the above RTV or LSR, each subject or crosslinker preferably comprises polydivinyldimethylsiloxane and polydihydridedimethylsiloxane.

Also preferably, the molar equivalent ratio of polydivinyldimethylsiloxane and polydihydride dimethylsiloxane is 1: 1.1 to 1: 5, and more preferably the molar equivalent ratio is 1: 2.5 to 1: 3.5.

The polydihydride dimethylsiloxane contained in excess causes crosslinking reaction upon further crosslinking to improve the interfacial adhesion strength and thus the breakdown strength.

When the molar equivalent ratio of polydihydride dimethylsiloxane is included below 1.1 with respect to polydivinyldimethylsiloxane 1, the improvement in interfacial adhesion is insufficient, and when the molar equivalent ratio exceeds 5, it may cause inefficiency of the manufacturing process. It may affect the physical properties of other materials.

More preferably, the molar equivalent ratio of polydihydride dimethylsiloxane is included in the molar equivalent ratio of 2.5 to 3.5 to achieve continuous provision in further crosslinking and process efficiency.

In addition, the liquid silicon insulating material and the liquid silicon semiconducting material preferably additionally contain a filler of inorganic silica component and a silicone resin so that crosslinking occurs by catalytic reaction of platinum.

The additional inclusion of the inorganic silica component filler and the silicone resin is based on consideration of the economics of the raw materials, and when contained, improves physical properties such as tensile strength and hardness.

Main crosslinking reaction is conventionally known by stirring using an appropriate mixing device such as a static mixer and mixing before the pot-life passes, and then main crosslinking at room temperature.

The additional crosslinking reaction is to be made at a high temperature and a long time, it is preferably made for 0.5 hours to 24 hours in an oven at a temperature of 100 ℃ ~ 220 ℃, it is made for 1 hour to 6 hours in an oven at a temperature of 150 ℃ ~ 180 ℃ More preferred.

If the reaction temperature is less than 100 ° C, the effect of additional crosslinking activity is low, and if the reaction temperature is higher than 220 ° C, adverse effects such as lowering of interfacial adhesion due to high temperature conditions are not preferable.

If the reaction time is less than 0.5 hours does not proceed enough reaction to adopt the additional cross-linking reaction according to the present invention, if more than 24 hours can not be a practical application.

When the reaction conditions are between 150 ° C and 180 ° C and between 1 hour and 6 hours, as shown in the examples described below, the effect of improving the adhesive strength and the dielectric breakdown property by additional crosslinking is more preferable. Do.

The method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties according to the present invention, through the cross-linking reaction in addition to the main cross-linking, induces the interfacial chemical reaction of the components remaining in the unreacted liquid silicone molding during the main cross-linking do.

In other words, in the case of using RTV or LSR, an unreacted hydride component is further reacted by an additional crosslinking reaction according to the above reaction conditions, thereby inducing interfacial adhesion. As a result, the interfacial adhesion is enhanced, and as a result, superior electrical insulating properties are conferred as compared with the main cross-linking treatment alone.

The method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties according to the present invention, liquid silicone rubber by inducing the interfacial adhesion of a specific component of the insulating-semiconductor liquid silicone rubber material whose additional crosslinking reaction has undergone the main crosslinking reaction In order to improve the adhesive properties and electrical insulation properties of the, it is completely different from the additional cross-linking process that has been used limitedly mainly to improve the mechanical properties of the liquid silicone rubber, in particular, the permanent compression shrinkage.

Hereinafter, the present invention will be described in more detail by explaining preferred embodiments of the present invention. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and the following examples are only common to those skilled in the art to complete the present disclosure. It is intended to facilitate the implementation of the invention to those with knowledge.

EXAMPLE

The adhesion test was conducted according to ASTM D 1876 as a T-peel test, and a combination of RTV insulator / LSR semiconductor or LSR insulator / LSR semiconductor was formed and tested. The dielectric breakdown strength was performed under the conditions of a boosting speed of 500V / sec according to ASTM D149 using Phenix equipment.

Table 1 shows the main crosslinking conditions and additional crosslinking conditions of the semiconductor, insulator according to the present embodiments.

division State Bridge Conditions (Whole Peninsula) Main crosslinking condition (whole semiconductor + insulator) Additional crosslinking condition (whole semiconductor + insulator) material Temperature (℃) Time (Hr) material Temperature (℃) Time (Hr) Temperature (℃) Time (Hr) Example 1 S 130 0.2 R1 45 5 130 0.5 Example 2 S 130 0.2 R1 45 5 130 6 Example 3 S 130 0.2 R1 45 5 200 One Example 4 S 130 0.2 R1 125 0.2 180 One Example 5 S 130 0.2 L1 125 0.2 130 6 Example 6 S 130 0.2 L1 125 0.2 150 2 Example 7 S 130 0.2 L1 125 0.2 180 One Example 8 S 130 0.2 L2 125 0.2 180 One Example 9 S 130 0.2 L2 125 0.2 200 12

S: Semiconductor LSR (Viscosity: 500,000 ~ 4,000,000 cps)

R1: Isolated RTV (Viscosity: 5,000-50,000 cps)

Nine conditions were selected as examples of the present invention.

After the semiconducting molding was made first, the insulator molding was poured into a mold cavity to prepare a semiconductor and an insulator combination (semiconductor + insulator) molding in the form of an electrical breakdown test. Finally, the crosslinking was carried out by properly sealing the molded product so as not to be contaminated in the curing oven.

FIG. 1A is a schematic view showing a mold 10 for forming a semiconducting material, and FIG. 1B is a schematic view showing a post-deformation structure of the semiconducting molding 20.

The main crosslinking conditions of the semiconductive material were molded using a hydraulic press for rubber molding into the mold 10 as shown in FIG. 1 under the same conditions of 130 ° C × 0.2 hours.

FIG. 2A is a schematic view showing a mold 100 for semiconducting and insulator combination molding, and FIG. 2B is a schematic view showing post-deformation structure of the semiconducting and insulator combination molding 200.

The combination material of the semiconductor and the insulator is placed under conditions of 45 ° C. × 5 hours (for RTV) or 125 ° C. × 0.2 hours (for LSR), and as shown in FIG. 2, for molding the rubber into the mold 100. It was molded using a hydraulic press.

The molded articles 20 and 200 thus formed were put in aluminum foil or an appropriate container in a curing oven of an appropriate capacity to further crosslink the reaction.

Table 2 shows the main crosslinking conditions, adhesive strength, and main breakdown strength according to the comparative examples.

division State Bridge Conditions (Whole Peninsula) Main crosslinking condition (whole semiconductor + insulator) Adhesive Strength (1) (kgf / in) Main breakdown strength (1kV / mm) material Temperature (℃) Time (Hr) material Temperature (℃) Time (Hr) Comparative Example 1 S 130 0.2 R1 45 5 1.2 22.0 Comparative Example 2 S 130 0.2 R1 125 0.2 2.5 23.0 Comparative Example 3 S 130 0.2 L1 125 0.2 3.0 22.5 Comparative Example 4 S 130 0.2 L2 125 0.2 3.5 23.5

S: Semiconductor LSR (Viscosity: 500,000 ~ 4,000,000 cps)

R1: Isolated RTV (Viscosity: 5,000-50,000 cps)

L1: Insulated LSR 1 (viscosity: 50,000 to 800,000 cps)

L2: Insulated LSR 2 (viscosity: 100,000-1,500,000 cps)

Adhesion strength (1) when the main crosslinking condition was applied alone without additional crosslinking condition showed 1.2 ~ 3.5kgf / in. The dielectric breakdown strength (1) when the main crosslinking condition was applied alone without additional crosslinking conditions also showed a range of 22 ~ 23.5kV / mm.

Table 3 shows the adhesive strength and dielectric breakdown strength according to the present embodiments.

division State Bridge Conditions (Whole Peninsula) Main crosslinking condition (whole semiconductor + insulator) Adhesive Strength (1) (kgf / in) Insulation Breaking Strength (1) (kV / mm) Additional crosslinking condition (whole semiconductor + insulator) Adhesive Strength (2) (kgf / in) Insulation Breaking Strength (2) (kV / mm) material Temperature (℃) Time (Hr) material Temperature (℃) Time (Hr) Temperature (℃) Time (Hr) Example 1 S 130 0.2 R1 45 5 1.2 22.0 130 0.5 2.0 22.5 Example 2 S 130 0.2 R1 45 5 1.2 22.0 130 6 3.5 23.5 Example 3 S 130 0.2 R1 45 5 1.2 22.0 180 One 22.0 24.5 Example 4 S 130 0.2 R1 125 0.2 2.5 23.0 180 One 22.5 25.0 Example 5 S 130 0.2 L1 125 0.2 3.0 22.5 130 6 5.0 23.0 Example 6 S 130 0.2 L1 125 0.2 3.0 22.5 150 2 10.0 25.0 Example 7 S 130 0.2 L1 125 0.2 3.0 22.5 180 One 19.0 27.0 Example 8 S 130 0.2 L2 125 0.2 3.5 23.5 180 One 17.0 28.0 Example 9 S 130 0.2 L2 125 0.2 3.5 23.5 200 12 13.0 26.5

The semiconducting materials of Examples 1 to 9 of the present invention were press-molded by setting the main crosslinking conditions at the same conditions of 0.2 hours at 130 ° C., and the semiconducting and insulator combination molding materials of Examples 1 to 3 in the case of RTV. As described above, in the case of 45 ° C. × 5 hours and LSR, the molding was performed under the same conditions of 125 ° C. × 0.2 hours as in the case of Examples 4 to 9, and molded by compression molding. Further cross-linking was carried out in the oven under the conditions of Examples 1 to 9 to measure the adhesive strength (2) and the dielectric breakdown strength (2) at this time.

As a result of the additional crosslinking conditions treated at a high temperature and for a long time compared to the main crosslinking alone, it can be seen that the adhesive strength (2) is higher than that of the adhesive strength (1). It can be seen that it is strengthened up to 4.5kV / mm.

This can be said that the additional reaction of the unreacted hydride component inside the molding composed of the semiconductor / insulator proceeds at the interface through the additional crosslinking, thereby improving the adhesive strength and increasing the dielectric breakdown strength by strengthening the adhesive strength.

In other words, the adhesive strength (1) is 1.2 ~ 3.5kgf / in, the dielectric breakdown strength (1) is in the range of 22 ~ 23.5kV / mm throughout the Examples 1 to 9 applying only the main cross-linking conditions, 150 When further crosslinking is performed under conditions of 1Hr to 6Hr at a high temperature of ˜180 ° C., it can be seen that the adhesive strength 2 and the dielectric breakdown strength 2 increase.

In particular, it can be seen that in the case of Examples 3, 4 and Examples 7, 8, and 9, the adhesive strength 2 and the dielectric breakdown strength 2 are simultaneously improved compared with those of Examples 1, 2, 5, and 6.

Therefore, given the additional crosslinking conditions at high temperature or for a long time, the dielectric breakdown strength increases due to the strengthening effect of the adhesive strength.

The method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties according to the present invention improves the adhesiveness of the additional liquid silicone rubber material and thereby enhances the interfacial properties to achieve excellent electrical insulating properties.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

1A is a schematic view showing a mold for forming a semiconducting material according to the present embodiment,

Figure 1b is a schematic diagram showing the structure after demolding the semiconducting molding according to the present embodiment,

2A is a schematic view showing a mold for forming a semiconductor and an insulator combination according to the present embodiment;

Figure 2b is a schematic diagram showing the post-deformation structure of the semiconducting and insulator combination molding according to this embodiment.

* Description of the main parts of the drawings *

10: mold for semiconducting molding 20: semiconducting molding

100: Mold for forming a combination of semiconductor and insulator

200: semi-conductor and insulator combination molding

Claims (9)

In the manufacturing method of the rubber molded article for the junction box using the insulating-semiconductor two-component addition liquid silicone rubber material, Liquid silicone rubber molding having excellent dielectric breakdown strength and adhesive properties, comprising the step of inducing interfacial adhesion through a main crosslinking reaction between the insulating material and the semiconductive material using a catalyst containing platinum. Manufacturing method. The method of claim 1, The additional crosslinking reaction is a method for producing a liquid silicone rubber molded article excellent in dielectric breakdown strength and adhesive properties, characterized in that the temperature is made from 0.5 hours to 24 hours at a temperature of 100 ℃ ~ 220 ℃. The method of claim 2, The additional crosslinking reaction is a method for producing a liquid silicone rubber molded article excellent in dielectric breakdown strength and adhesive properties, characterized in that the temperature is made from 1 hour to 6 hours at a temperature of 150 ℃ ~ 180 ℃. The method according to any one of claims 1 to 3, Wherein said insulating material and said semiconducting material comprise polydivinyldimethylsiloxane and polydihydride dimethylsiloxane in a main or crosslinking agent. The method of claim 4, wherein The polydivinyl dimethyl siloxane and the polydihydride dimethyl siloxane is a method of producing a liquid silicone rubber molded article excellent in dielectric breakdown strength and adhesive properties, characterized in that the molar equivalent ratio is 1: 1.1 to 1: 5. The method of claim 5, The polydivinyl dimethyl siloxane and the polydihydride dimethyl siloxane is a method of producing a liquid silicone rubber molded article excellent in dielectric breakdown strength and adhesive properties, characterized in that the molar equivalent ratio is 1: 2.5 ~ 1: 3.5. The method of claim 4, wherein The insulating material is a method for producing a liquid silicone rubber molded article excellent in dielectric breakdown strength and adhesive properties, characterized in that it further comprises a filler of inorganic silica component and silicone resin. The method according to any one of claims 1 to 3, The insulating material is an insulating RTV having a viscosity of 5,000 to 50,000 cps or an insulating LSR having a viscosity of 50,000 to 1,500,000 cps. The method according to any one of claims 1 to 3, The semiconductive material is a method for producing a liquid silicone rubber molded article having excellent dielectric breakdown strength and adhesive properties, characterized in that the semiconducting LSR having a viscosity of 500,000 ~ 4,000,000 cps.