Method for applying a two-part addition-curable silicone composition and apparatus therefor

Abstract

To provide a method of applying a small amount with the excellent workability without impairing the room temperature curability of a two-pack type addition curable silicone composition and a device for the same.SOLUTION: There is provided an application device of a two-pack type addition curable silicone composition including: a static agitator having an introduction port for introducing each liquid of the two-pack type addition curable silicone composition and a plurality of elements for mixing the liquids; a cooler for cooling the agitator; and a nozzle for discharging the mixed addition curable silicone composition by a small amount. There is also provided an application method of the two-pack type addition curable silicone composition comprising the steps of: introducing each liquid of the two-pack type addition curable silicone composition into the static agitator; preparing the addition curable silicone composition by mixing the liquids while cooling the liquids; and discharging the composition by a small amount from the nozzle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for applying a two-part addition-curable silicone composition. [Background technology]

[0002] In recent years, the miniaturization and high precision of electric and electronic components have created a demand for intermittent application of small amounts of curable silicone compositions, on the order of a few microliters, onto electric and electronic components and substrates.Typically, two-component addition-curable silicone compositions are used as curable silicone compositions because they have a fast curing reaction and do not produce by-products during curing, and a static mixer is used to mix the two components.

[0003] In two-component addition-curable silicone compositions, the addition reaction begins immediately after the two components come into contact. Therefore, when a small amount is applied, the viscosity increases inside the static mixer, and the rate of decrease in the amount applied from the start of application can exceed 30% after one hour. In severe cases, clogging can occur inside the static mixer or at the discharge section.

[0004] To solve these problems, it has been proposed to reduce the room temperature curing property of the two-component addition-curable silicone composition, and Patent Documents 1 to 3 propose achieving both ease of application and curing by laminating substrates to which each component of the two-component addition-curable silicone composition has been applied separately from two different nozzles.

[0005] Meanwhile, Patent Documents 4 to 7 propose a method of forming a cured product by mixing a two-component addition-curable silicone composition in a static mixer cooled to -60°C to +5°C and discharging the mixture into a mold at +25°C to +100°C or into water at +25°C or higher. Furthermore, Patent Document 8 proposes providing a cooling device to the static mixer in order to cool the liquid in the static mixer.

[0006] However, Patent Documents 4 to 8 are not concerned with applying small amounts of two-component addition-curable silicone compositions. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-091576 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-091948 [Patent Document 3] Japanese Patent Application Laid-Open 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 Laid-Open No. 2011-036788 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method and apparatus for applying small amounts of a two-part addition-curable silicone composition with good workability without impairing the room temperature curing properties of the composition. [Means for solving the problem]

[0009] This device is characterized by comprising a static mixer having inlets for introducing each part of the two-part addition-curable silicone composition and having multiple elements for mixing the parts, a cooler for cooling the mixer, and a nozzle for discharging the mixed addition-curable silicone composition in small amounts.

[0010] In this apparatus, the internal volume of the static stirrer is preferably 1 to 5 ml, and the number of elements in the static stirrer is preferably 7 to 40. Furthermore, in this apparatus, it is preferable that the static stirrer and the cooler are separable.

[0011] This method is also characterized by introducing each part of the two-part addition-curable silicone composition into a static mixer, mixing the parts while cooling them to prepare an addition-curable silicone composition, and then extruding the composition little by little from a nozzle.

[0012] In this method, the curable silicone composition is preferably ejected intermittently, and the ejection amount is preferably 0.5 to 5 μl per shot.

[0013] Furthermore, in this method, it is preferable that the two-component addition-curable silicone composition has a pot life of 10 to 60 minutes at 25°C as specified in JIS K 6870:2008, and that the cooling temperature is 20°C or lower. [Effects of the Invention]

[0014] The coating method and apparatus of the present invention are characterized by their ease of use and the ability to coat small amounts without impairing the room temperature curing properties of the two-part addition-curable silicone composition. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of the device with a partial cutaway. [Figure 2] FIG. 2 is a perspective view, partially cut away, of another of the present devices. [Figure 3] FIG. 3 is a perspective view showing that the device can be separated into a static stirrer and a cooler. [Figure 4] FIG. 4 is a perspective view of the device with a partial cutaway showing the syringe for dispensing the two-part addition-curable silicone composition attached. [Figure 5] FIG. 5 is a perspective view showing a coating operation using this device. [Figure 6] FIG. 6 is a perspective view showing another coating operation using the present device. [Figure 7] FIG. 7 is a perspective view showing another coating operation using the present device. [Figure 8] FIG. 8 is a perspective view showing another coating operation using the present device. [Figure 9] FIG. 9 is a semi-logarithmic graph showing the relationship between the temperature and the pot life of the curable silicone composition used in Example 1. [Figure 10] FIG. 10 is a semi-logarithmic graph showing the relationship between the temperature and the pot life of the curable silicone composition used in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Terminology> The term "viscosity" as used in this specification means the value (unit: mPa s or Pa s) at 25°C measured using a B-type rotational viscometer in accordance with JIS K 7117-1:1999 "Plastics - Liquid, emulsion or dispersion resins - Measurement of apparent viscosity using a Brookfield rotational viscometer."

[0017] The term "pot life" as used in this specification means the time it takes for the viscosity to double from the viscosity immediately after mixing two components at a specified temperature, according to the method specified in JIS K 6870:2008 "Adhesives - Method for determining the pot life (usable time) of multi-component adhesives."

[0018] <Method of applying a two-component addition-curable silicone composition and apparatus therefor> The coating method and the apparatus therefor of the present invention will be described in detail with reference to the drawings. Fig. 1 is a partially cutaway perspective view showing an example of this apparatus. The apparatus comprises a static stirrer 1, a cooler 2 provided to cover the stirrer 1, and a nozzle 3 connected to the stirrer 1.

[0019] The static mixer 1 is provided with inlets 11 and 11' for introducing each part of the two-component addition-curable silicone composition. These inlets are connected to containers (not shown) for storing the two parts, respectively, or to pipes or tubes (not shown) for transferring the two parts from the containers. Syringes or cartridges can be used as these containers. The two parts are transferred to the inlets 11 and 11' in fixed amounts. The two parts may be transferred in a pre-cooled state. The internal volume of the static mixer 1 is not limited, but is preferably 1 to 5 ml, since small amounts must be applied intermittently. The static mixer 1 is also provided with multiple elements 12 for mixing the two parts. 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, but a square plate twisted 180 degrees is often used to separate and mix the two parts. The static mixer 1 has a cylindrical structure in which multiple right elements, each made of a square plate twisted 180 degrees to the right, and multiple left elements, each twisted 180 degrees to the left, are arranged alternately inside the cylinder, thereby minimizing shearing and effectively suppressing drift.

[0020] The two liquids are introduced into one end of the static mixer 1 and, as they flow to the other end, are divided and mixed by the elements 12, eventually forming a uniform composition. If there is a significant difference in the viscosities of the two liquids, one liquid may easily pass through the elements 12, resulting in an inconsistent uniform composition. Therefore, it is preferable to match the viscosities of the two liquids in advance. Furthermore, if the viscosity of the two liquids is low, each liquid may easily pass through the elements 12, resulting in an inconsistent uniform composition. In such cases, it is preferable to either optimize the shape of the elements or increase the number of elements. While increasing the number of elements improves the uniformity of the resulting composition, it also increases the retention time of the composition within the static mixer 1, potentially resulting in thickening or gelation of the composition. Therefore, it is preferable to minimize the number of elements based on the application speed. Specifically, the number of elements is preferably within the range of 7 to 40, or preferably within the range of 7 to 30. Furthermore, to facilitate internal cleaning of the static mixer 1, it is preferable that the elements 12 be detachable from the static mixer 1.

[0021] The static mixer 1 is equipped with a cooler 2. The cooler 2 is equipped with inlet and outlet ports 11, 11' for introducing and discharging a refrigerant. The cooler 2 cools the two liquids, preventing thickening and gelation of the composition obtained by mixing them. There are no limitations on the cooling temperature used by the cooler 2, but it is generally preferable to set it to a temperature of 20°C or lower, 15°C or lower, or 5°C or lower. On the other hand, a temperature of -5°C or higher, 0°C or higher, or 5°C or higher is preferable, as this prevents thickening of the curable silicone composition due to cooling and reduces condensation on the composition or its surroundings after application. This cooling temperature can be easily estimated from the pot life of the composition and the time (residence time) from when the curable silicone composition is introduced into the static mixer until it is discharged, which is determined from the internal volume and discharge rate of the static mixer. For example, if the viscosity of the curable silicone composition at 25°C is relatively low, at 100 Pa·s or less, the composition can be cooled to a temperature that results in a pot life of at least 0.5, at least 0.6, at least 0.8, or at least 1 time the residence time. Alternatively, if the viscosity of the curable silicone composition at 25°C exceeds 100 Pa·s, the composition can be cooled to a temperature that results in a pot life of at least 1.5, or at least 2 times the residence time. Cooling the composition to a predetermined temperature or below can prevent changes in application rate due to thickening of the composition and clogging within the static mixer or discharge section. The refrigerant used in the cooler 2 is not limited, and examples include liquids such as water, an aqueous solution of alcohol, an aqueous solution of diethylene glycol, and oil; and gases such as air and nitrogen. It is preferable to select an appropriate refrigerant depending on the cooling temperature. In Figure 1, the refrigerant flows freely within the cooler 2, but it is preferable to control the flow of the refrigerant to avoid localized cooling of the static mixer 1. For example, in Fig. 2, the refrigerant flows through a conduit 22 connected to the inlet and outlet of the refrigerant. This allows the static agitator 1 to be uniformly cooled. Also, as shown in Fig. 3, in this device, the static agitator 1 and the cooler 2 may be separable.

[0022] Figure 4 is a partially cutaway perspective view of the apparatus equipped with a syringe 4 for supplying a two-component addition-curable silicone composition. As shown in Figure 4, by attaching a container such as a syringe or cartridge to the apparatus, the apparatus itself can be made smaller. Also, as shown in Figure 4, a constant amount of the two components can be supplied into the static mixer 1 by an air supply mechanism (not shown) connected to the syringe 4.

[0023] The addition-curable silicone composition mixed in the static stirrer 1 is discharged little by little from a nozzle 3. There are no restrictions on the amount of discharge, but to achieve intermittent small-amount application, a discharge of 0.5 to 5 μl per shot is preferred. In addition, although the addition-curable silicone composition is discharged from a nozzle 3 in Figures 1 to 4, it is also possible to apply the addition-curable silicone composition in even finer amounts by replacing the nozzle 3 with a jet nozzle.

[0024] The two-component addition-curable silicone composition to which the present invention is applicable is not limited, but preferably has a viscosity at 25°C, as specified in JIS K 7117-1:1999 "Plastics - Liquid, emulsion, or dispersion resins - Method for measuring apparent viscosity using a Brookfield rotational viscometer," in the range of 100 to 1,000,000 mPas, or 500 to 500,000 mPas. Furthermore, fast-curing silicone compositions with a pot life at 25°C (the time it takes for the viscosity to double from the viscosity immediately after mixing the two components) of 10 to 60 minutes, as specified in JIS K 6870:2008 "Adhesives - Determination of pot life (usable life) of multi-component adhesives," can also be used. In this case, the cooling temperature of the static stirrer 1 is preferably 20°C or lower, 15°C or lower, or 5°C or lower. On the other hand, a temperature of -5°C or higher, 0°C or higher, or 5°C or higher is preferred, as this reduces the risk of thickening of the curable silicone composition due to cooling and condensation on the composition or its surroundings after application. The pot life of this two-component addition-curable silicone composition at a cooling temperature can be estimated from a semi-logarithmic graph created using the temperatures at at least three different points and the actual measured values ​​of pot life at that time. When a two-component addition-curable silicone composition with such a pot life is applied intermittently at a discharge rate of 5 μl / shot, the rate of decrease in the applied amount from the start of application can be kept to less than 30% even after one hour. Examples of such two-component addition-curable silicone compositions include DOWSIL® (Dow-Toray Industries, Inc.) TM EA-4700 CV ADHESIVE A&B, manufactured by Dow Toray Industries, Inc. TM TC-4525 CV GAPFILLER A&B is an example.

[0025] Figures 5 to 8 show a coating operation using this device. In Figure 5, this device is fixed, and small amounts of addition-curable silicone composition 6 are applied to substrate 5 in dots. To apply small amounts intermittently, substrate 5 itself can be moved in the X and Y directions by an XY stage mechanism 7. This XY stage mechanism has an XY stage with a slide member slidably mounted on guide shafts parallel to each other along the X axis on a horizontal plane, and another slide member slidably mounted on guide shafts parallel to each other along the Y axis, perpendicular to the X axis on the horizontal plane, to move substrate 5 on the stage to any desired position. This XY stage mechanism allows small amounts of addition-curable silicone composition to be intermittently applied to substrate 5 without moving this device.

[0026] 6, the substrate 5 is fixed, and the device is movable in the X and Y directions by an XY slide mechanism. This XY slide mechanism is a mechanism that moves the device to any position using a slide member that is slidably mounted on guide shafts that are parallel to each other along the X axis on a horizontal plane, and a stand for the device that is slidably mounted on a slide member in the Y axis direction, which is perpendicular to the X axis on the horizontal plane. This XY slide mechanism makes it possible to intermittently apply small amounts of addition-curable silicone composition to the substrate 5 without having to move the large substrate.

[0027] Furthermore, in Figure 7, the combined use of an XY slide mechanism and an XY stage mechanism allows both the device and the substrate to be moved, enabling small amounts of addition-curable silicone composition to be intermittently applied at higher speeds. Also, in Figure 8, small amounts of addition-curable silicone composition are intermittently applied in the form of a bead. The addition-curable silicone composition 6 thus applied to the substrate 5 can be cured at room temperature or, if necessary, by heating. [Example]

[0028] The coating method and the apparatus therefor of the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[0029] [Example 1] A two-part addition-curable silicone composition consisting of the following parts A and B was prepared, and this was cooled to a specified temperature. The applicator was then used to apply the composition at the initial discharge pressure, and the applicability was evaluated. The viscosity was measured at 25°C using a rotational viscometer at a shear rate of 10 (1 / s), in accordance with JIS K 7117-1:1999.

[0030] (Preparation of Solution A) Solution A, with a viscosity of 1,080 mPa·s, was prepared by uniformly mixing 50 parts by mass of a dimethylpolysiloxane terminated at both molecular chain ends with dimethylvinylsiloxy groups and with a viscosity of 360 mPa·s, 50 parts by mass of a dimethylpolysiloxane terminated at both molecular chain ends with dimethylvinylsiloxy groups and with a viscosity of 2,000 mPa·s, and a 1,3-divinyl-tetramethyldisiloxane platinum complex (an amount such that the platinum metal in the composition was 25 ppm by mass).

[0031] (Preparation of Solution B) Solution B with a viscosity of 850 mPa·s was prepared by uniformly mixing 50 parts by mass of a dimethylpolysiloxane terminated at both molecular chain terminals with dimethylvinylsiloxy groups and having a viscosity of 360 mPa·s, 50 parts by mass of a dimethylpolysiloxane terminated at both molecular chain terminals with dimethylvinylsiloxy groups and having a viscosity of 2,000 mPa·s, 10 parts by mass of a dimethylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular chain terminals with trimethylsiloxy groups and having a viscosity of 5 mPa·s, 1 part by mass of a dimethylpolysiloxane terminated at both molecular chain terminals with dimethylhydrogensiloxy groups and having a viscosity of 10 mPa·s, and 2-phenyl-3-butyn-2-ol (in an amount that would result in 100 ppm by mass in the composition).

[0032] The viscosity at 25°C of the curable silicone composition obtained immediately after mixing the above-mentioned parts A and B in a volume ratio of 1:1, and the pot life at specified temperatures specified in JIS K 6870:2008 are listed in Table 1. In addition, temperatures other than 25°C and the pot life at those temperatures were estimated using a semi-logarithmic graph (Figure 9) created from actual measurements, and these results are also listed in Table 1.

[0033] [Table 1]

[0034] The above-mentioned solutions A and B were loaded into a MIXPAC dual syringe (CD050-01-PP) and introduced into a static mixer (MIXPAC static mixer MA0517-0413; 30 elements; 2.0 ml internal volume) so that the volume ratio of solutions A to B was 1:1. The static mixer was cooled to a predetermined temperature using a cooler while mixing, and the solution was applied to the substrate from a nozzle at a rate of 1.0 μl / shot every 2 seconds. The initial amount of solution applied was compared with the amount applied after 30 minutes to determine the reduction in the amount of solution applied. A reduction of 10% or less in the amount of solution applied was evaluated as "good," a reduction of more than 10% to 30% was evaluated as "fair," and a reduction of more than 30% was evaluated as "poor." The results are shown in Table 2.

[0035] [Table 2]

[0036] The above-mentioned solutions A and B were filled into a dual syringe (CD050-01-PP) manufactured by MIXPAC, and then introduced into a static mixer (MIXPAC static mixer MA0517-0413 (number of elements: 30; internal volume: 2.0 ml) so that the volume ratio of solution A to solution B was 1:1. The static mixer was cooled to a predetermined temperature using a cooler while mixing, and the solution was applied to the substrate from the nozzle at a rate of 1.0 μl / shot every 2 seconds. The application process was then stopped for 60 minutes and then restarted. The initial application amount was compared with the application amount after 60 minutes to determine the reduction in the application amount. Note that if the reduction in the application amount was 10% or less, the application quality was evaluated as "good," if it was more than 10% but not more than 30%, the application quality was evaluated as "fair," and if it was more than 30%, the application quality was evaluated as "poor." The results are shown in Table 3.

[0037] [Table 3]

[0038] [Example 2] As a two-component addition-curable silicone composition, DOWSIL® (Dow Toray Industries, Inc.) TM EA-4700 CV ADHESIVE A&B was used. The properties are shown in Table 4. In addition, temperatures other than 25°C and the pot life at those temperatures were estimated using a semi-logarithmic graph (Figure 10) created from the actual measurements, and are also shown in Table 4.

[0039] [Table 4]

[0040] DOWSIL TM EA-4700 CV ADHESIVE A & B were loaded into a MIXPAC dual syringe (CD050-01-PP) and transferred to a static mixer (MIXPAC Static Mixer MA0517-0413; 30 elements; 2.0 ml internal volume) at a 1:1 volume ratio of A to B. The static mixer was cooled to a predetermined temperature using a cooler while mixing, and the mixture was applied to the substrate from a nozzle at a rate of 1.2 μl / shot every 2 seconds. The initial amount of coating was compared with the amount of coating after 30 minutes to determine the reduction in coating volume. A reduction of 10% or less in coating volume was evaluated as "good," a reduction of more than 10% to 30% was evaluated as "fair," and a reduction of more than 30% was evaluated as "poor." The results are shown in Table 5.

[0041] [Table 5]

[0042] [Example 3] As a two-component addition-curable silicone composition, DOWSIL® (Dow Toray Industries, Inc.) TM TC-4525 CV GAPFILLER A&B was used, and its properties are shown in Table 6.

[0043] [Table 6]

[0044] DOWSIL TM TC-4525 CV GAPFILLER A & B was loaded into a MIXPAC dual syringe (CD050-01-PP) and introduced into a static mixer (MIXPAC Static Mixer MA6.3-12-S; 12 elements; 1.9 ml internal volume) so that the volume ratio of A to B was 1:1. The static mixer was cooled to a predetermined temperature using a cooler while mixing, and the solution was applied to the substrate from a nozzle at a rate of 1.5 μl / shot every 2 seconds. The initial amount of coating was compared with the amount of coating after 30 minutes to determine the reduction in coating volume. A reduction of 10% or less in coating volume was evaluated as "good," a reduction of more than 10% to 30% was evaluated as "fair," and a reduction of more than 30% was evaluated as "poor." The results are shown in Table 7.

[0045] [Table 7]

[0046] From the evaluation of the coating properties above, it can be seen that by cooling the static mixer to 20°C or less, 15°C or less, or 5°C or less with a cooler, it is possible to coat a small amount with good workability. Furthermore, even if the coating work is interrupted, it was found that by continuing to cool the static mixer, it is possible to coat a small amount well even after the coating work is resumed. [Industrial Applicability]

[0047] The coating method and apparatus of the present invention allows for easy application of small amounts of addition-curable silicone composition without impairing the room-temperature curing properties of the composition, and is therefore suitable, for example, as a method and apparatus for intermittently applying small amounts of addition-curable silicone composition to electrical or electronic components or their substrates. [Explanation of symbols]

[0048] 1 Static stirrer 2 cooler 3 nozzles 4. Syringe for supplying two-component addition-curable silicone composition 5. Substrate 6,6' addition-curable silicone composition 7 XY stage mechanism 8 XY slide mechanism 11, 11' Inlet ports for each component of the two-component addition-curable silicone composition 12 Elements 21,21' Refrigerant inlet / outlet 22 Refrigerant conduit

Claims

[Claim 1] A method for applying a two-part addition-curable silicone composition, comprising: introducing each part of the two-part addition-curable silicone composition into a static mixer, mixing the parts while cooling them to prepare an addition-curable silicone composition, and then extruding the composition little by little from a nozzle; The curable silicone composition is intermittently ejected in an amount of 0.5 to 5 μl per shot; A coating method in which the pot life of the two-component addition-curable silicone composition at 25°C as specified in JIS K 6870:2008 is 10 to 60 minutes, the cooling temperature is 20°C or lower, and the pot life is the time it takes for the viscosity to double from the viscosity immediately after mixing the two components.

Images