Silicone rubber bonding method using plasma treatment

Abstract

The present invention relates to a method for joining silicone rubber using plasma treatment, and more specifically, is characterized in that one surface of the silicone rubber is plasma treated to modify it to be hydrophilic, and the silicone rubber is joined to another silicone rubber by utilizing the surface-modified portion.

Description

[Technical field]

[0001] The present invention relates to a method for joining silicone rubber using plasma treatment, and more specifically, is characterized in that one surface of the silicone rubber is treated with plasma to modify it to be hydrophilic, and the silicone rubber is joined to another silicone rubber by utilizing the surface-modified portion. [Background technology]

[0002] Recently, with the rapid development of cutting-edge industries, new materials that require excellent chemical stability have been actively developed.

[0003] Silicon rubber is a new material that is similar to rubber and is a highly functional industrial material that is different from other organic materials (rubber, plastic, etc.). It is more widely used than any other form of elastomer due to its advantages such as high temperature stability, low temperature stability, super electrical insulation, fire resistance, flame retardancy, tasteless and non-toxic, permanent unchanging, environmental friendliness, chemical resistance, UV radiation resistance, biochemical inertness, transparency, and diverse mechanical properties.

[0004] That is, due to the above-mentioned advantages, the silicone rubber is widely used in various silicone rubber bonding fields such as bonding coatings for automobile interior and exterior parts, bonding of clothing and shoes, electric wire manufacturing, medical equipment manufacturing, utility pole protective films, and consumer goods manufacturing.

[0005] However, like most polymer compounds, silicone rubber is hydrophobic and has low surface energy, making it difficult to bond silicone rubber to itself or to other materials, limiting its applications. Therefore, in order to bond silicone rubber to other materials, a special adhesive or a heat fusion method is usually used.

[0006] However, using the special adhesive as mentioned above is not environmentally friendly since it requires the use of a separate adhesive, and when using the heat fusion method, it may cause damage to the product, the shape of the silicone rubber may be deformed, and various other problems may occur, such as large energy consumption.

[0007] Therefore, the present inventors have been researching ways to solve the above problems, and have discovered that when a plasma treatment is performed on the surface of silicone rubber, polar groups are formed on the hydrophobic surface, which allows smooth adhesion between silicone rubbers, thereby completing the present invention.

[0008] In this regard, Korean Patent Registration No. 10-1330149 discloses an adhesive for bonding silicone rubber. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been devised to solve the above-mentioned problems of the prior art, and has an object to provide a method for modifying the surface of silicone rubber by utilizing plasma treatment.

[0010] Another object of the present invention is to provide a method for joining the surface-modified silicone rubber.

[0011] Other detailed objects of the present invention will be clearly understood by those skilled in the art through the specific details described below. [Means for solving the problem]

[0012] As a technical means for achieving the above technical objectives, One aspect of the present invention is The method includes the steps of: subjecting one surface of the silicone rubber to a plasma treatment; The plasma treatment is carried out at 1 atmosphere and a plasma temperature of less than 300° C. Alternatively, it may be carried out at normal pressure and normal temperature.

[0013] The silicone rubber is in the form of a sheet, and the thickness of the silicone rubber sheet may be 0.1T to 5T or more, or the thickness of the silicone rubber sheet may be 0.1 um to 150 mm.

[0014] The gas used in the plasma treatment may be air, oxygen (O2), or carbon dioxide (CO2).

[0015] When air is used in the plasma treatment, the supply flow rate of the air may be 1 L / Wh to 10 L / Wh, and when carbon dioxide (CO2) is used, the supply flow rate of the carbon dioxide (CO2) may be 1 L / Wh to 3 L / Wh.

[0016] When air is used in the plasma treatment, the plasma output may be 0.05 WATT / mm2 to 0.8 WATT / mm2, and when carbon dioxide (CO2) is used, the plasma output may be 0.15 WATT / mm2 to 0.5 WATT / mmm2.

[0017] The discharge frequency of the plasma may be 1 kHz to 27.12 Mhz.

[0018] The plasma treatment interval may be 1 mm to 50 mm.

[0019] The plasma treatment energy may be 0.05 WATT / mm2 to 0.8 WATT / mm2.

[0020] The surface energy of the surface-modified silicone rubber with respect to water may be 10 mN / m to 60 mN / m higher than the surface energy before the surface treatment.

[0021] Another aspect of the present invention is The present invention provides a method for bonding silicone rubber, the method including a step of bonding the silicone rubber, one surface of which has been modified by the above method, to another silicone rubber by pressure bonding.

[0022] The pressure bonding is for removing air bubbles, and may be performed at a pressure of 0.1 kg / cm2 to 10 kg / cm2 for 0.1 seconds to 60 seconds.

[0023] Meanwhile, prior to this, this specification states that the terms and words used in the claims should not be interpreted limitedly to their ordinary or dictionary meanings, but should be interpreted in the meaning and concept consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concept of terms in order to explain their invention in the best possible manner.

[0024] Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and therefore, at the time of this application, there may be various equivalents and modifications that can replace them. Effect of the Invention

[0025] When the surface of silicone rubber is modified using the plasma treatment according to the present invention and the modified surface is used to bond silicone rubber, excellent adhesive performance can be exhibited without using a separate adhesive, which is environmentally friendly.

[0026] It can also be very efficient since no damage is caused to the silicone rubber itself and it can be adhered more easily.

[0027] In addition, the effects of the present invention will be clearly understood by those skilled in the art through the specific details described below or during the process of implementing the present invention. [Brief description of the drawings]

[0028] [Figure 1] 1 is a schematic diagram illustrating a surface modification and adhesion process of silicone rubber according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather as defined by the claims which follow.

[0030] Furthermore, the terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. Throughout the specification of the present invention, the expression "comprises" a certain component does not exclude other components, but means that other components can be further included, unless otherwise specified.

[0031] The first aspect of the present application is The method includes the steps of: subjecting one surface of the silicone rubber to a plasma treatment; The plasma treatment is carried out at normal pressure and room temperature, or at a plasma temperature of less than 300° C. at 1 atmosphere.

[0032] The method for modifying the surface of silicone rubber according to the first aspect of the present application will be described in detail below.

[0033] In one embodiment of the present application, the silicone rubber may be in the form of a sheet, i.e., it may have a certain thickness and length as shown in Fig. 1, and the thickness of the silicone rubber sheet may be about 0.1T to 5T, and according to one embodiment of the present invention, it may be about 1T.

[0034] Meanwhile, the length of the silicone rubber sheet is not particularly limited, and may be a length suitable for the field of application. Also, the material of the silicone rubber is not particularly limited, and may be a commonly used silicone rubber sheet.

[0035] In an embodiment of the present application, the plasma treatment may be performed by injecting a certain reaction gas under application of voltage using a low-temperature / atmospheric pressure plasma surface treatment device capable of performing surface treatment at room temperature.

[0036] In one embodiment of the present application, the method for modifying the surface of silicone rubber may include a step of plasma-treating one surface of the silicone rubber. That is, the plasma-treated one surface of the silicone rubber may be used to bond with another silicone rubber. However, the silicone rubber should not be interpreted as being limited to plasma-treating only one surface, and it should be understood that if silicone rubber needs to be bonded to both surfaces as necessary, the other surface should also be plasma-treated.

[0037] In one embodiment of the present application, the gas used in the plasma treatment may be air or carbon dioxide (CO2). Here, the air may refer to atmospheric air containing oxygen. Meanwhile, the air or carbon dioxide may be a high-purity gas having a purity of 99% or more, and preferably has a purity of about 99.9%.

[0038] In one embodiment of the present application, when air is used for the plasma treatment, the supply flow rate of the air may be 1 L / Wh to 10 L / Wh, and preferably 3 L / Wh to 5 L / Wh, and according to one embodiment of the present invention, 2 L / Wh to 4 L / Wh. Meanwhile, if the supply flow rate of the air is less than 1 L / Wh, the surface modification of the silicone rubber may not be performed smoothly due to the small amount of air supplied, and if it exceeds 10 L / Wh, it may be uneconomical since the amount of air required for the surface modification is already exceeded.

[0039] In an embodiment of the present application, when air is used for the plasma treatment, the plasma output (applied voltage when plasma is generated) may be 0.05 WATT / mm2 to 0.8 WATT / mm2, and most preferably in the range of 0.25 WATT / mm2 to 0.4 WATT / mm2.

[0040] Meanwhile, according to one embodiment of the present invention, when air is used for the plasma treatment, the plasma output may be 0.25 WATT / mm2 to 0.4 WATT / mm2. If the plasma output is less than 0.05 WATT / mm2, the plasma treatment may not be performed smoothly due to the low applied voltage, and if it exceeds 0.8 WATT / mm2, it may be uneconomical since the required applied voltage is exceeded. Meanwhile, as the applied voltage during plasma generation increases, the discharge density increases, and the adhesive strength may improve as the development of active functional groups on the silicone rubber surface increases.

[0041] In one embodiment of the present application, when carbon dioxide (CO2) is used in the plasma treatment, the supply flow rate of the carbon dioxide (CO2) may be 1 L / Wh to 3 L / Wh, and most preferably 2 L / Wh to 3 L / Wh, and according to one embodiment of the present invention, 2 L / Wh to 2.5 L / Wh.

[0042] On the other hand, if the supply flow rate of carbon dioxide (CO2) is less than 1 L / Wh, the surface modification of the silicone rubber may not be performed smoothly due to the low content of carbon dioxide supplied, and if it exceeds 3 L / Wh, it may be uneconomical since the content of carbon dioxide required for surface modification is already exceeded.

[0043] In an embodiment of the present application, when carbon dioxide (CO2) is used for the plasma treatment, the plasma output (applied voltage when generating plasma) may be 0.15 WATT / mm2 to 0.5 WATT / mm2, and most preferably in the range of 0.25 WATT / mm2 to 0.4 WATT / mm2.

[0044] Meanwhile, according to one embodiment of the present invention, when carbon dioxide is used for the plasma treatment, the plasma output may be 0.25 WATT / mm2 to 0.4 WATT / mm2. If the plasma output is less than 0.1 WATT / mm2, the applied voltage is low and the plasma treatment may not be performed smoothly, and if it exceeds 0.5 WATT / mm2, it may be uneconomical since the required applied voltage has already been exceeded. Meanwhile, as the applied voltage during plasma generation increases, the discharge density increases, and the adhesive strength may be improved as the development of active functional groups on the silicone rubber surface increases.

[0045] In one embodiment of the present application, the discharge frequency of the plasma may be 1 kHz to 27.12 MHz. Specifically, the discharge frequency means the frequency of a low-temperature / atmospheric pressure plasma surface treatment apparatus, and may be an RF frequency. In this case, the discharge frequency of the plasma may be about 30 kHz to 60 kHz according to one embodiment of the present invention. Meanwhile, the transformer of the plasma surface treatment apparatus may also use RF power.

[0046] In one embodiment of the present application, the plasma treatment energy may be 0.05 WATT / mm2 to 0.8 WATT / mm2. The most preferred range is 0.25 WATT / mm2 to 0.4 WATT / mm2. According to one embodiment of the present invention, the plasma treatment may be about 0.4 WATT / mm2. Meanwhile, it is preferred that the plasma treatment is performed once in the above speed range. If the plasma treatment energy is less than 0.05 WATT / mm2, the energy is too low and the surface modification may not be performed smoothly, and if it exceeds 0.8 WATT / mm2, it may be inefficient.

[0047] In one embodiment of the present application, the plasma treatment interval may be 1 mm to 50 mm, preferably 1 mm to 20 mm, and according to one embodiment of the present invention, may be about 10 mm. In this case, the plasma treatment interval may refer to the interval between one surface of the silicone rubber and the reactive gas as a plasma supply source. Meanwhile, if the plasma treatment interval is less than 1 mm or exceeds 50 mm, the interval between one surface of the silicone rubber and the reactive gas as a plasma supply source is too narrow or too far, which may cause a problem that the surface modification of the silicone rubber by the plasma is not performed smoothly.

[0048] In an embodiment of the present application, the surface energy of the surface-modified silicone rubber with respect to water may be 10 mN / m or more higher than the surface energy before the surface treatment.

[0049] In this case, the surface contact angle may specifically mean a contact angle on one surface of a surface-modified silicone rubber.

[0050] In other words, the surface of silicone rubber is originally made of silicon (Si) and hydrocarbons and has hydrophobic properties, but when the surface is subjected to plasma treatment, radicals are generated in the silicon (Si) or hydrocarbons (such as CH2), and the radicals recombine with oxygen groups to introduce polar groups such as hydroxyl groups (-OH) or carbonyl groups (-C=O-), which may give the surface hydrophilic properties.

[0051] Therefore, one surface of the surface-modified silicone rubber having hydrophilic properties may have a low contact angle with water as described above.

[0052] A second aspect of the present application is According to the first aspect of the present application, there is provided a method for bonding silicone rubber, the method including a step of bonding a silicone rubber having one surface modified to another silicone rubber by pressure bonding.

[0053] Detailed descriptions of parts that overlap with the first aspect of the present application have been omitted, but the contents described in the first aspect of the present application may be equally applied even if the description is omitted in the second aspect.

[0054] Hereinafter, the silicone rubber bonding method according to the second aspect of the present application will be described in detail.

[0055] In one embodiment of the present application, the bonding of the silicone rubber may be a bonding of two or more silicone rubbers, and in this case, the surfaces of the silicone rubbers to be bonded may each be surface-modified by the method according to the first aspect of the present application, or only one of the silicone rubber surfaces may be surface-modified. That is, although only the process of bonding two silicone rubbers is shown in Fig. 1, it should be understood that other silicone rubbers can be bonded to the other surfaces, and in this case, it should be understood that at least one of the surfaces is surface-modified according to the first aspect of the present application.

[0056] In one embodiment of the present application, the pressure bonding may be performed at a pressure of 0.1 kg / cm2 to 10 kg / cm2, preferably at a pressure of 0.1 kg / cm2 to 5 kg / cm2, and according to one embodiment of the present invention, at a pressure of about 1 kg / cm2. Meanwhile, if the pressure bonding is performed at less than 0.1 kg / cm2, the pressure may be too low and the bonding between the silicone rubber may not be performed smoothly, and if the pressure bonding is performed at more than 10 kg / cm2, the pressure may be too high and the silicone rubber may be deformed.

[0057] In one embodiment of the present application, the compression may be performed for 1 to 60 seconds, preferably for 1 to 20 seconds, and more preferably for 1 to 10 seconds. Meanwhile, according to one embodiment of the present invention, it may be performed for about 5 seconds. If the compression is performed for less than 1 second, the compression time may be too short and the bonding between the silicone rubbers may not be performed smoothly, and if the compression is performed for more than 60 seconds, the bonding time may be exceeded, which may be inefficient.

[0058] In an embodiment of the present disclosure, the silicone rubber bonded through the silicone rubber bonding method may have a cutting strength of about 300 times or more compared to the cutting strength of the silicone rubber before bonding.

[0059] More specifically, the cutting strength of the silicone rubber before joining may be less than about 0.5 kgf / cm2, but when two pieces of silicone rubber are joined as shown in Figure 1, the cutting strength of the joined silicone rubber may be greater than or equal to about 30 kgf / cm2.

[0060] Therefore, the silicone rubber bonded by the above method may be widely applicable to various silicone rubber bonding fields such as bonding and coating of automobile interior and exterior parts, clothing and shoe bonding, electric wire manufacturing, medical equipment manufacturing, utility pole protective film, and consumer goods manufacturing due to its excellent physical properties.

[0061] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be embodied in various different forms and should not be construed as being limited to the embodiments set forth herein. Example 1. Surface modification of silicone rubber using air (output: 500W)

[0062] A general silicon sheet having a size of 50 mm×50 mm and a thickness of 1T was prepared.

[0063] A plasma treatment was performed on one surface of the prepared silicon sheet under the following conditions.

[0064] - Ambient temperature: Room temperature -Plasma temperature: less than 60℃ -Gas used: Air (clean dry air, CDA) -Gas supply flow rate: 4L / Wh~5.5L / Wh -Plasma method: Atmospheric pressure plasma -Discharge frequency: 30khz~27.12Mhz -Power: 500W -Plasma energy: 0.25WATT / mm2 -Plasma treatment interval: 10mm Example 2. Surface modification of silicone rubber using air (output: 1,000 W)

[0065] The surface modification of silicone rubber was carried out in the same manner as in Preparation Example 1, except that the output was 1,000 W. Example 3: Surface modification of silicon rubber using carbon dioxide (output: 550 W)

[0066] The surface modification of silicone rubber was carried out in the same manner as in Preparation Example 1, except that carbon dioxide (CO2) was used as the gas, the gas supply flow rate was set to 1 L / Wh to 2 L / Wh, and the output was set to 550 W. Example 4. Surface modification of silicon rubber using carbon dioxide (output: 800W)

[0067] The surface modification of silicone rubber was carried out in the same manner as in Preparation Example 3, except that the output was 800 W. Example: Bonding of silicone rubber sheets

[0068] The silicone rubber sheets whose surfaces had been modified in each of the above Production Examples 1 to 4 were bonded together. That is, for example, the silicone rubber sheet whose surface had been modified in Production Example 1 was bonded to a silicone rubber sheet whose surface had been modified by the same method (the method of Production Example 1), and the silicone rubber sheets whose surfaces had been modified in Production Examples 2 to 4 were also bonded in the same manner.

[0069] At this time, the pressure applied between the silicone rubbers was 1 kg / cm2, the compression time was 5 seconds, and after compression, the pieces were left to stand for 60 seconds under atmospheric conditions at normal pressure. Experimental example 1: Contact angle measurement experiment

[0070] In each of Production Examples 1 to 4, the contact angle of water on one surface of each of the surface-modified silicone rubbers was measured and is shown in Table 1 below.

[0071] [Table 1]

[0072] As shown in Table 1, the contact angle of the silicon sheet before plasma treatment was measured three times and was about 90 degrees, confirming that it had hydrophobic properties. However, the contact angle after plasma treatment was measured less than 5 degrees in Preparation Examples 1 to 3, confirming that the surface was modified with excellent hydrophilic properties, and in Preparation Example 4, the contact angle was measured three times and was less than about 60 degrees, confirming that the surface was similarly modified with hydrophilic properties. Experimental example 2. Cutting strength measurement experiment

[0073] The cutting strength of the silicone rubber sheets before bonding and the cutting strength of the silicone rubber sheets bonded according to the above-mentioned Examples were measured and are shown in Table 2 below.

[0074] [Table 2]

[0075] As shown in Table 2, the cut strength of the silicone sheet before bonding was a low strength value of less than 0.5 kgf / cm2, whereas the cut strength of the silicone sheet bonded according to the embodiment of the present invention was a high strength value of 30 kgf / cm2 or more, demonstrating excellent cut strength. Therefore, it was confirmed that when the silicone rubber sheet surface-modified according to the present invention is bonded, it has excellent physical properties and can be usefully used in various industrial fields.

[0076] Although the present invention has been described in detail above with reference to the drawings and preferred embodiments, the scope of the technical idea of ​​the present invention is not limited to these drawings and embodiments. Therefore, various modifications or equivalent embodiments may exist within the scope of the technical idea of ​​the present invention. Therefore, the scope of the technical idea of ​​the present invention should be analyzed based on the claims, and any technical idea equivalent to or within the equivalent scope should be interpreted as belonging to the scope of the present invention.

Claims

1. The method includes the steps of: subjecting one surface of the silicone rubber to a plasma treatment; The method for modifying the surface of silicone rubber, wherein the plasma treatment is carried out at a plasma temperature of less than 300° C. under 1 atmosphere.

2. The silicone rubber is in the form of a sheet. The method for modifying a rubber surface according to claim 1, wherein the thickness of the silicone rubber sheet is 0.1 um to 150 mm.

3. 2. The method for modifying the surface of silicone rubber according to claim 1, wherein the gas used in the plasma treatment is air or carbon dioxide (CO2).

4. When air is used in the plasma treatment, the supply flow rate of the air is 1 L / Wh to 10 L / Wh; 4. The method for modifying a surface of silicone rubber according to claim 3, wherein when carbon dioxide (CO2) is used, the supply flow rate of the carbon dioxide (CO2) is 1 L / Wh to 3 L / Wh.

5. When air is used for the plasma treatment, the plasma output is 0.05 WATT / mm2 to 0.8 WATT / mm2; The method for modifying a surface of silicone rubber according to claim 3, wherein when carbon dioxide (CO2) is used, the plasma output is 0.15 WATT / mm2 to 0.5 WATT / mm2.

6. The method for modifying a surface of silicone rubber according to claim 1, wherein the discharge frequency of the plasma is 1 kHz to 27.12 Mhz.

7. The method for modifying the surface of silicone rubber according to claim 1, wherein the plasma treatment energy is 0.05 WATT / mm2 to 0.8 WATT / mm2.

8. The method for modifying a surface of silicone rubber according to claim 1, wherein the plasma treatment interval is 1 mm to 50 mm.

9. 2. The method for modifying a surface of silicone rubber according to claim 1, wherein the surface energy of the surface-modified silicone rubber with respect to water is 10 mN / m to 60 mN / m higher than the surface energy before the surface treatment.

10. A method for bonding silicone rubber, comprising a step of bonding a silicone rubber having one surface modified by the method according to claim 1 to another silicone rubber by pressure bonding.

11. The method for bonding silicone rubber according to claim 10, wherein the pressure bonding is performed at a pressure of 0.1 kg / cm2 to 10 kg / cm2 for 1 to 60 seconds.

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