Coating method and apparatus for two-component addition-curing polysiloxane compositions

Abstract

Topic: This invention provides a method and apparatus for the non-destructive, room-temperature curable, and workable small-batch coating of a two-component addition-curing polysiloxane composition. Solution: A coating apparatus and method for a two-component addition-curing polysiloxane composition. The coating apparatus includes a static stirrer, a cooler, and a nozzle. The static stirrer has inlets for introducing the liquids of the two-component addition-curing polysiloxane composition and multiple elements for mixing the liquids. The cooler is used to cool the stirrer. The nozzle is used to spray the mixed addition-curing polysiloxane composition out in small batches. The coating method is characterized in that the liquids of the two-component addition-curing polysiloxane composition are introduced into the static stirrer, and the liquids are mixed while being cooled to prepare the addition-curing polysiloxane composition. Then, the composition is sprayed out in small batches from the nozzle.

Description

Technical Field

[0001] This invention relates to a coating method and apparatus for a two-component addition-curing polysiloxane composition. Prior Technology

[0002] In recent years, due to the miniaturization and high precision of electrical and electronic components, there is a need to intermittently apply curable polysiloxane (PVC) compositions in small amounts of about a few µl onto electrical and electronic components and substrates. Typically, two-component addition-curing PVC compositions are used as curable PVC compositions in terms of fast curing reaction and no by-products generated during curing, and static stirrers are used to mix the two components.

[0003] Two-component addition-curing polysiloxane compositions have the following problems: since the two components undergo an addition reaction immediately upon contact, they become viscous in the static mixer when applied in small quantities. The reduction rate of coating amount from the start of coating exceeds 30% after 1 hour, and even causes blockage in the static mixer or the spray section.

[0004] To address this issue, a method has been proposed to reduce the room temperature curability of two-component addition-curing polysiloxane compositions. Patent documents 1-3 propose a method that simultaneously achieves coating workability and curing performance by bonding substrates coated with the liquids of two-component addition-curing polysiloxane compositions from two different nozzles.

[0005] On the other hand, Patent Documents 4-7 propose a method in which a two-component addition-curing polysiloxane composition is mixed using a static mixer cooled to -60°C to +5°C, and then sprayed into a mold at +25°C to +100°C or into water at +25°C or higher to form a solidified product. Furthermore, Patent Document 8 proposes a method of installing a cooling device in the static mixer to cool the liquid inside the static mixer.

[0006] However, none of the patent documents 4 to 8 involve the application of small amounts of two-component addition-curing polysiloxane compositions. Knowledge of technical documents Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-091576 Patent Document 2: Japanese Patent Application Publication No. 2015-091948 Patent Document 3: Japanese Patent Application Publication No. 2015-214703 Patent Document 4: Japanese Patent Application Publication No. 62-207611 Patent Document 5: Japanese Patent Application Publication No. 62-264920 Patent Document 6: Japanese Patent Application Publication No. 63-046230 Patent Document 7: Japanese Patent Application Publication No. 05-005063 Patent Document 8: Japanese Patent Application Publication No. 2011-036788 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The purpose of this invention is to provide a method and apparatus for applying small quantities of a non-destructive two-component addition-curing polysiloxane composition at room temperature with good workability. Technical means to solve the problem

[0010] The device is characterized by comprising: a static stirrer having inlets for introducing the liquids of the two-component addition-curing polysiloxane composition, and having a plurality of elements for mixing the liquids; a cooler for cooling the stirrer; and a nozzle for spraying the mixed addition-curing polysiloxane composition in small, sequential amounts.

[0011] In this apparatus, the internal volume of the static stirrer is preferably 1 to 5 ml, and the number of components inside the static stirrer is preferably 7 to 40. Furthermore, it is preferable that the static stirrer and the cooler are separable in this apparatus.

[0012] In addition, the method is characterized in that each liquid of the two-liquid addition-curing polysiloxane composition is introduced into a static stirrer, and the liquid is mixed while being cooled to prepare the addition-curing polysiloxane composition. Then, the composition is sprayed out in small amounts from the nozzle one by one.

[0013] In this method, it is preferable to intermittently spray the curable polysiloxane composition, with a spray volume preferably of 0.5~5 µl / 1 shot.

[0014] Furthermore, in this method, it is preferable that the two-component addition-curing polysiloxane composition has a pot life of 10 to 60 minutes at 25°C as specified in JIS K 6870:2008, and a cooling temperature of 20°C or below. Invention Effects

[0015] The coating method and apparatus of the present invention have the following characteristics: room temperature curing of non-destructive two-component addition-curing polysiloxane compositions and good workability for small-batch coating. Simple Explanation of the Diagram

[0016] [Figure 1] is a perspective view of the device with a partial cross-section. [Figure 2] is a perspective view of another part of the device with a partial cross-section. [Figure 3] is a perspective view showing that the device can be separated into a static stirrer and a cooler. [Figure 4] is a perspective view of the device with a partial cross-section, showing the state in which the syringe for supplying the two-component addition-curing polysiloxane composition is installed. [Figure 5] is a perspective view of the coating operation using this device. [Figure 6] is a perspective view showing other coating operations using this device. [Figure 7] is a perspective view showing other coating operations using this device. [Figure 8] is a perspective view showing other coating operations using this device. [Figure 9] is a semi-logarithmic graph showing the relationship between temperature and pot life for the curable polysiloxane composition used in Example 1. [Figure 10] is a semi-logarithmic graph showing the relationship between temperature and pot life for the curable polysiloxane composition used in Example 2. Implementation

[0017] <Definition of Terms>

[0018] The term "viscosity" as used in this manual refers to the value at 25°C (unit: mPa·s or Pa·s) measured by a Type B rotational viscometer as specified in JIS K 7117-1:1999 "Plastics - Liquid, emulsion or dispersion resins - Method for determination of apparent viscosity using a Brinell rotational viscometer".

[0019] The term "potential life" used in this specification refers to the time from the viscosity immediately after the two components are mixed at a specified temperature until that viscosity doubles, as specified in JIS K 6870:2008 "Adhesives - Method for determining the pot life (usable time) of multi-component adhesives". <Coating Method and Apparatus for Two-Fluid Addition-Curing Polysiloxane Compositions>

[0020] The coating method and apparatus of the present invention will be described in detail with reference to the accompanying drawings.

[0021] Figure 1 is a perspective view showing a partial cross-section of one example of the device. The device includes a static stirrer 1, a cooler 2 disposed to cover the stirrer 1, and a nozzle 3 connected to the stirrer 1.

[0022] The static stirrer 1 is provided with inlets 11 and 11' for introducing the two liquids of the addition-curing polysiloxane composition. Containers (not shown) for storing the two liquids, or tubes or pipes (not shown) for transferring the two liquids from these containers, are connected to these inlets. Alternatively, syringes or cartridges can be used as the containers. The two liquids are transferred to the inlets 11 and 11' in a fixed amount. Alternatively, the two liquids can be transferred in a pre-cooled state. The internal volume of the static stirrer 1 is not limited, but since intermittent small-volume coating is required, 1 to 5 ml is preferred. Furthermore, the static stirrer 1 is provided with multiple elements 12 for mixing the two liquids. The elements 12 are made of metals such as stainless steel or titanium; or plastics such as polyethylene, polypropylene, nylon, or polyvinylidene chloride. Their shape is not limited; for separating and mixing the two liquids, a quadrilateral plate twisted 180° is used. By configuring multiple right elements formed by twisting quadrilateral plates 180° to the right and left elements formed by twisting them 180° to the left alternately inside the cylinder of the static mixer 1, it is possible to suppress shearing as much as possible while effectively suppressing flow deviation.

[0023] The two liquids are introduced from one end of the static stirrer 1 and are divided and mixed by the element 12 as they flow to the other end, soon becoming a homogeneous composition. When there is a significant difference in viscosity between the two liquids, one liquid may easily pass through the element 12, resulting in an inability to obtain a homogeneous composition. Therefore, it is preferable to pre-select liquids with the same viscosity. Furthermore, when the viscosity of the two liquids is low, they may also easily pass through the element 12, resulting in an inability to obtain a homogeneous composition. In this case, it is preferable to make the shape of the element appropriate or to increase the number of elements. Additionally, the more elements there are, the higher the homogeneity of the obtained composition, but the longer the composition remains in the static stirrer 1, raising concerns about thickening and gelation of the composition. Therefore, it is preferable to set the number of elements to the minimum to match the coating speed; specifically, it is preferable to have a number of elements in the range of 7 to 40 or 7 to 30. In addition, regarding the ease of cleaning the interior of the static mixer 1, element 12 is preferably separable from the static mixer 1.

[0024] A cooler 2 is provided in the static mixer 1. The cooler 2 is provided with inlet / outlet ports 21 and 21' for introducing and discharging the refrigerant. By cooling the two liquids with the cooler 2, thickening and gelation of the mixed composition can be suppressed. The cooling temperature of the cooler 2 is not limited, but it is generally preferred to be below 20°C, below 15°C, or below 5°C. On the other hand, in order to prevent thickening of the cured polysiloxane composition due to cooling and condensation of the composition and its surroundings after coating, it is preferred to be above -5°C, above 0°C, or above 5°C. In addition, the cooling temperature can be easily estimated based on the following two factors: the time from the introduction of the cured polysiloxane composition into the static mixer to its discharge (residence time) calculated based on the internal volume and discharge rate of the static mixer, and the pot life of the aforementioned composition. For example, when the viscosity of the curable polysiloxane composition at 25°C is relatively low, below 100 Pa·s, it is sufficient to cool the composition to a temperature that is at least 0.5 times, 0.6 times, 0.8 times, or 1 times the aforementioned residence time, relative to the usable period. Conversely, when the viscosity of the curable polysiloxane composition at 25°C exceeds 100 Pa·s, it is sufficient to cool the composition to a temperature that is at least 1.5 times or 2 times the aforementioned residence time, relative to the aforementioned residence time. Cooling the composition to below the specified temperature can suppress changes in coating amount caused by viscosity increase, and prevent clogging in static mixers or spray nozzles. The refrigerant used in the cooler 2 is not limited; examples include liquids such as water, aqueous solutions of alcohol, aqueous solutions of diethylene glycol, and oil; and gases such as air and nitrogen. It is preferable to select an appropriate refrigerant based on the cooling temperature. In Figure 1, the refrigerant flows freely within the cooler 2. However, to avoid localized cooling of the static stirrer 1, it is preferable to control the flow of the refrigerant. For example, in Figure 2, the refrigerant flows within the conduit 22 connecting its inlet and outlet. Therefore, the static stirrer 1 can be cooled uniformly. Furthermore, as shown in Figure 3, in this device, the static stirrer 1 and the cooler 2 can also be separated.

[0025] Figure 4 is a partial cross-sectional perspective view of the syringe 4 for supplying the two-component addition-curing polysiloxane composition installed in this device. As shown in Figure 4, by installing containers such as syringes and cartridges in this device, the device itself can be minimized. In addition, in Figure 4, a certain amount of the two-component mixture can be supplied to the static stirrer 1 by means of an air supply mechanism (not shown) connected to the syringe 4.

[0026] The addition-curing polysiloxane composition, after being mixed in a static mixer 1, is sequentially sprayed out in small amounts from nozzle 3. The spray volume is not limited, but for intermittent, small-volume coating, 0.5 to 5 µl / shot is preferred. Alternatively, while the addition-curing polysiloxane composition is sprayed from nozzle 3 as shown in Figures 1 to 4, it can also be further micro-coated by installing a jet-type dispensing nozzle instead of nozzle 3.

[0027] The application of the two-component addition-curing polysiloxane composition of this invention is not limited, but preferably has a viscosity at 25°C within the range of 100~1,000,000 mPa·s or 500~500,000 mPa·s as specified in JIS K 7117-1:1999 "Plastics - Liquid, emulsion or dispersion resins - Method for determination of apparent viscosity using a Brookfield rotational viscometer". Alternatively, it can also be applied to have a fast-curing property with a pot life (the time from the viscosity immediately after mixing the two components until that viscosity doubles) of 10~60 minutes at 25°C as specified in JIS K 6870:2008 "Adhesives - Method for determining the pot life (usable time) of multi-component adhesives". At this point, the cooling temperature of the static stirrer 1 is preferably below 20°C, below 15°C, or below 5°C. On the other hand, to minimize the risk of increased viscosity of the cured polysiloxane composition due to cooling, and to prevent condensation on the composition and its surroundings after coating, it is preferably above -5°C, above 0°C, or above 5°C. Furthermore, the pot life of the two-component addition-curing polysiloxane composition at the cooling temperature can be estimated using a semi-logarithmic graph constructed from measured values ​​of the temperature at at least three different points and the pot life at that time. When the two-component addition-curing polysiloxane composition with this pot life is intermittently applied at a spray rate of 5 µl / shot, the reduction rate of the coating amount from the start of coating is less than 30% even after 1 hour. Examples of such two-component addition-curing polysiloxane compositions include DOWSIL™ EA-4700 CV ADHESIVE A&B manufactured by Dow Toray Inc., and DOWSIL™ TC-4525 CV GAPFILLER A&B manufactured by Dow Toray Inc.

[0028] Figures 5 to 8 illustrate the coating operation using this apparatus. In Figure 5, the apparatus is fixed. To apply the addition-curing polysiloxane composition 6 in small, intermittent dots to the substrate 5, the substrate 5 is movable along the X and Y axes using an XY stage mechanism 7. This XY stage mechanism moves the substrate 5 to any position on the stage using an XY stage that has sliding members slidably mounted on guide axes parallel to each other along the X-axis on a horizontal plane, and sliding members slidably mounted on guide axes parallel to each other along the Y-axis orthogonal to the X-axis on a horizontal plane. This XY stage mechanism allows the addition-curing polysiloxane composition to be intermittently applied in small amounts to the substrate 5 without moving the apparatus.

[0029] Furthermore, in Figure 6, the substrate 5 is fixed, and the device can move along the X and Y axes via an XY sliding mechanism. This XY sliding mechanism allows the device to move to any position using two components: a sliding member slidably mounted on guide shafts parallel to each other along the X-axis on a horizontal plane, and a support for the device slidably mounted on a sliding member along the Y-axis, which is orthogonal to the X-axis on a horizontal plane. Using this XY sliding mechanism, addition-curable polysiloxane components can be intermittently and in small amounts coated onto the substrate 5 without moving a larger substrate.

[0030] Furthermore, in Figure 7, by using both the XY sliding mechanism and the XY stage mechanism, both the device and the substrate can move independently, allowing for faster, intermittent, small-volume application of the addition-curing polysiloxane composition. Additionally, Figure 8 shows the addition-curing polysiloxane composition being applied in a linear, intermittent, small-volume manner. The addition-curing polysiloxane composition 6 thus applied to the substrate 5 can be cured at room temperature or, as needed, by heating. Example

[0031] The coating method and apparatus of the present invention are described in detail by way of examples, but the present invention is not limited to these examples. [Example 1]

[0032] A two-component addition-curable polysiloxane composition comprising liquid A and liquid B was prepared. Coating was performed using this coating apparatus cooled to a specified temperature and set to the initial ejection pressure. The coatability at this point was evaluated. Furthermore, the viscosity was measured at 25°C using a rotational viscometer with a shear rate of 10 (1 / s), according to JIS K 7117-1:1999. (Preparation of Solution A)

[0033] A solution with a viscosity of 1080 mPa·s was prepared by uniformly mixing 50 parts by mass of dimethyl polysiloxane with molecular chains capped at both ends of dimethyl vinyl siloxy groups (360 mPa·s), 50 parts by mass of dimethyl polysiloxane with molecular chains capped at both ends of dimethyl vinyl siloxy groups (2000 mPa·s), and a platinum 1,3-divinyl-tetramethyldisiloxane complex (in which platinum metal is present in an amount of 25 ppm by mass). (Preparation of Solution B)

[0034] A solution B with a viscosity of 850 mPa·s was prepared by uniformly mixing 50 parts by mass of dimethyl polysiloxane with molecular chains capped at both ends of dimethylvinylsilalkoxy (viscosity 360 mPa·s), 50 parts by mass of dimethyl polysiloxane with molecular chains capped at both ends of dimethylvinylsilalkoxy (viscosity 2,000 mPa·s), 10 parts by mass of dimethylsiloxane-methylhydrosiloxane copolymer with molecular chains capped at both ends of trimethylsilalkoxy (viscosity 5 mPa·s), 1 part by mass of dimethyl polysiloxane with molecular chains capped at both ends of dimethylhydrosilalkoxy (viscosity 10 mPa·s), and 2-phenyl-3-butyn-2-ol (in the composition in an amount of 100 ppm by mass).

[0035] The viscosity at 25°C and the pot life at the specified temperature as defined in JIS K 6870:2008 of the cured polysiloxane composition obtained by mixing liquid A and liquid B at a volume ratio of 1:1 are recorded in Table 1. In addition, the pot life at temperatures other than 25°C and at those temperatures were estimated using a semi-logarithmic plot (Figure 9) prepared based on measured values, and are also recorded in Table 1.

[0036] Table 1 Viscosity (mPa·s) of liquid A at 25°C 1080 Viscosity (mPa·s) of liquid B at 25°C 850 Solution A and solution B are freshly mixed at a volume ratio of 1:1. 960 Viscosity at 25°C (mPa·s) Applicable period (minutes) 25℃ 23 (measured value) 20℃ 45 (estimated value) 15℃ 90 (measured value) 5℃ 320 (measured value) -5℃ 1200 (estimated value)

[0037] Liquids A and B were filled into a dual-barrel syringe (CD050-01-PP) manufactured by MIXPAC, and introduced into a static mixer (MA0517-0413; 30 elements; 2.0 ml internal volume) at a volume ratio of 1:1. The static mixer was cooled to a specified temperature using a cooler while mixing, and the mixture was applied to the substrate at a rate of 1.0 µl / shot every 2 seconds from the nozzle. The initial coating amount was compared with the coating amount after 30 minutes to determine the coating amount reduction rate. A coating amount reduction rate of less than 10% was rated as "good," more than 10% but less than 30% was rated as "slightly good," and more than 30% was rated as "poor." The results are shown in Table 2.

[0038] Table 2 Addition-cured polysiloxane components -5 5 15 20 25 Preparation temperature (°C) Initial coating amount (µl / shot) 1.0 1.0 1.0 1.0 1.0 Coating volume (µl / shot) after 30 minutes 1.0 1.0 1.0 0.9 0.5 Coating amount reduction rate (%) 0 0 0 10 50 Coating properties good good good good bad

[0039] In addition, the above-mentioned solutions A and B were filled into a dual-barrel syringe (CD050-01-PP) manufactured by MIXPAC, and introduced into a static stirrer (MSPAC MA0517-0413 static mixer (30 elements; internal volume 2.0 ml) with a volume ratio of solution A to solution B of 1:1. The mixture was carried out while the static stirrer was cooled at a specified temperature using a cooler, and applied to the substrate at a rate of 1.0 µl / shot every 2 seconds from the nozzle. The coating process was then stopped after 60 minutes and restarted. The initial coating amount was compared with the coating amount after 60 minutes to determine the coating amount reduction rate. A coating amount reduction rate of less than 10% was rated as "good," more than 10% but less than 30% was rated as "slightly good," and more than 30% was rated as "poor." The results are shown in Table 3.

[0040] Table 3 Addition-cured polysiloxane components -5 25 Preparation temperature (°C) Initial coating amount (µl / shot) 1.0 1.0 Coating volume (µl / shot) after 60 minutes 1.0 0 Coating amount reduction rate (%) 0 100 Coating properties good bad [Example 2]

[0041] As a two-component addition-curing polysiloxane composition, DOWSIL™ EA-4700 CV ADHESIVE A&B manufactured by Dow Toray Inc. was used. Its properties are shown in Table 4. In addition, the temperatures other than 25°C and the pot life at those temperatures were estimated using a semi-logarithmic plot (Figure 10) prepared based on measured values, and are also recorded in Table 4.

[0042] Table 4 Viscosity (Pa·s) of liquid A at 25°C twenty four Viscosity (Pa·s) of liquid B at 25°C 18 Viscosity (Pa·s) at 25°C immediately after mixing liquid A and liquid B in a 1:1 volume ratio. 27 Applicable period (minutes) 25℃ 17 (measured value) 20℃ 29 (measured value) 15℃ 51 (measured value) 5℃ 150 (estimated value) -5℃ 460 (estimated value)

[0043] DOWSIL™ EA-4700 CV ADHESIVE A&B was filled into a dual-barrel syringe (CD050-01-PP) manufactured by MIXPAC. The mixture was introduced into a static mixer (MA0517-0413; 30 elements; 2.0 ml internal volume) manufactured by MIXPAC at a volume ratio of 1:1. The static mixer was cooled to a specified temperature using a cooler while mixing. The mixture was applied to the substrate at a rate of 1.2 µl / shot every 2 seconds from the nozzle. The initial coating amount was compared with the coating amount after 30 minutes to determine the coating amount reduction rate. A coating amount reduction rate of less than 10% was rated as "good," more than 10% but less than 30% was rated as "slightly good," and more than 30% was rated as "poor." The results are shown in Table 5.

[0044] Table 5 Preparation temperature (°C) of addition-curing polysiloxane compositions -5 5 15 20 25 Initial coating amount (µl / shot) 1.2 1.2 1.2 1.2 1.2 Coating volume (µl / shot) after 30 minutes 1.2 1.2 1.1 0.9 0.5 Coating amount reduction rate (%) 0 0 8 25 58 Coating properties good good good Slightly better bad [Example 3]

[0045] As a two-component addition-curing polysiloxane composition, DOWSIL™ TC-4525 CV GAPFILLER A&B manufactured by Dow Toray Corporation was used. Its properties are shown in Table 6.

[0046] Table 6 Viscosity (Pa·s) of liquid A at 25°C 207 Viscosity (Pa·s) of liquid B at 25°C 193 Viscosity (Pa·s) at 25°C immediately after mixing liquid A and liquid B in a 1:1 volume ratio. 217 Applicable period (minutes) 25℃ 40 (measured value) 15℃ 130 (measured value) 5℃ 450 (measured value)

[0047] DOWSIL™ TC-4525 CV GAPFILLER A&B was filled into a dual-barrel syringe (CD050-01-PP) manufactured by MIXPAC. The mixture was introduced into a static mixer (MIXPAC MA6.3-12-S; 12 elements; 1.9 ml internal volume) at a 1:1 volume ratio of A to B. Mixing was performed while the static mixer was cooled to a specified temperature using a cooler. The mixture was applied to the substrate at a rate of 1.5 µl / shot every 2 seconds from the nozzle. The initial coating amount was compared with the coating amount after 30 minutes to determine the coating amount reduction rate. A coating amount reduction rate of less than 10% was rated as "good," more than 10% but less than 30% was rated as "slightly good," and more than 30% was rated as "poor." The results are shown in Table 7.

[0048] Table 7 Preparation temperature (°C) of addition-curing polysiloxane compositions 5 15 25 Initial coating amount (µl / shot) 1.5 1.5 1.5 Coating volume (µl / shot) after 30 minutes 1.4 1.1 0.5 Coating amount reduction rate (%) 7 27 67 Coating properties good Slightly better bad

[0049] Based on the above evaluation of coatability, it can be seen that by cooling the static agitator to below 20°C, 15°C, or 5°C using a cooler, small-scale coating can be performed with good workability. In addition, by continuing to cool the static agitator when the coating operation is interrupted, small-scale coating can also be performed well after the coating operation is resumed. Industrial availability

[0050] The coating method and apparatus of the present invention do not damage the room temperature curing property of the two-component addition-curing polysiloxane composition and can be applied in small quantities with good workability. Therefore, it is suitable, for example, as a method and apparatus for intermittently applying small quantities of addition-curing polysiloxane composition to electrical and electronic components or their substrates.

[0051] 1: Static mixer 2: Cooler 3: Nozzle 4: Syringe for supplying two-component addition-curing polysiloxane compositions 5:Substrate 6, 6': Addition-cured polysiloxane composition 7: XY platform mechanism 8: XY sliding mechanism 11, 11': Inlet ports for each liquid in a two-component addition-curing polysiloxane composition. 12: Components 21, 21': Refrigerant inlet / outlet 22: Refrigerant conduit

Claims

1. A coating method for a two-component addition-curing polysiloxane composition, characterized in that each liquid of the two-component addition-curing polysiloxane composition is introduced into a static stirrer, and the liquids are mixed while being cooled to prepare the addition-curing polysiloxane composition. Then, the composition is sprayed out in small amounts from a nozzle one after another, and the curing polysiloxane composition is sprayed out intermittently at a spraying rate of 0.5~5 µl / spray. The pot life of the two-component addition-curing polysiloxane composition at 25°C as specified in JIS K 6870:2008 is 10~60 minutes, and the cooling temperature is below 20°C. The above-mentioned pot life is the time from the viscosity immediately after the two components are mixed until the viscosity becomes twice the original value.

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