JPH0655554A - Manufacture for on-spot molding gasket of silicone foam - Google Patents

Abstract

PURPOSE:To obtain a gasket of an on-spot foaming type efficiently, to save the using amount of material and to enhance the air-tight properties, by measuring and mixing a liquid silicone foam composition by a specific device and, discharging, foaming and hardening the mixture at a required position. CONSTITUTION:Measuring and mixing of a liquid silicone composition, and discharging the mixture to a desired position are conducted by a measuring/ feeding device and a mixing/discharging device. The measuring/feeding device quantitatively takes and supplies the silicone composition from a storing tank storing the liquid silicone composition. The mixing/discharging device consists of a mixing chamber 9 where the liquid silicone foam composition sent, from the measuring/feeding device is accommodated, a cooling jacket 5 for cooling the mixing chamber by circulating a cooling medium, a rotor 7 with pin-shaped, wing-shaped or screw-like projections 6 in the outer periphery thereof, and a discharging nozzle 8 for discharging the mixed silicone composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a gasket used for sealing a seal portion of various containers, sealing a pipe connection portion (flange), and the like, and more specifically, mixing and discharging a liquid silicone composition at room temperature. The present invention relates to a method for producing an in-situ molded gasket made of silicone foam that is heated at room temperature or, if necessary, before and after casting in a step before and after casting to foam and cure.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION AND ITS PROBLEMS Conventionally, for example, a so-called standard-shaped gasket has been used in which vulcanized rubber or the like is poured into a molding die and then cured to be molded into a predetermined shape. ing. As the coated gasket, a cast type polyurethane elastomer manufactured by a cast molding method is used.
In the above conventional gasket manufacturing method, as a raw material of the gasket, such as vulcanized rubber and polyurethane elastomer,
A non-foaming rubbery material was used. However, in these conventional gasket manufacturing methods, it is necessary to produce a large number of gaskets molded into a certain shape, which is not suitable for practical use in the case of producing a large number of kinds of small amounts of gaskets. On the other hand, in the type using polysiloxane rubber, in recent years, when sealing around the engine in automobile manufacturers, etc., a condensation reaction type room temperature curable polysiloxane rubber is applied to the surface to be sealed in an uncured state,
There is a wet type, which is a sealing method of forming a polysiloxane rubber layer that is adhered to a base material on the sealing surface while being pressure-bonded and cured at room temperature, and its workability, hermeticity and heat resistance are highly evaluated. However, there is a problem that it is difficult to reuse because it adheres to both sealed surfaces. On the other hand, there is a dry type that uses a 2-pack type addition-type polysiloxane rubber. This is a method of mixing 2 packs, applying it to the surface to be sealed in an uncured state, and heating and curing to seal the sealing surface. One side is adhered or one side is adhered to the base material, and is suitable when the sealed surface is repeatedly used. On the other hand, the heat resistance temperature of polysiloxane rubber is
Although it improves to 200 ° C, it has a high density because it is a solid rubber and it is used in large amounts, but on the other hand, it cannot be applied to the surface pressure due to the high rubber hardness. Limits will come up. Here, "Method for forming gasket foam" in Japanese Patent Laid-Open No. 3-94876
Discloses a method of forming a gasket using silicone foam. However, in this technology,
Since the shape of the rotor in the mixing chamber is such that grooves are engraved on the surface, most of the mixed liquid exists in the grooves of the rotor and must be mixed if the gasket material is relatively fluid. There was a problem that it was difficult to control the pot life because the temperature was too high and the temperature was likely to rise.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to measure, mix, and discharge a liquid silicone composition at room temperature, and heat it at room temperature or as needed to foam-cure on site. It is an object of the present invention to provide a method for manufacturing an in-situ molded gasket that enables the molding of the gasket in various parts.

[0004]

The present inventors have conducted extensive studies to achieve the above object, and as a result, essentially two-pack type liquid silicone composition is weighed, mixed, discharged, and then foamed and cured at room temperature at room temperature. In manufacturing an in-situ molded gasket, it was found that the use of a specific metering / liquid feeding device and a mixing / discharging device was effective, and the present invention was completed. That is, the present invention is a process in which essentially two-pack type liquid silicone composition is weighed, the weighed composition is mixed, and the resulting mixture is discharged to a desired site to foam and cure in situ. A method for producing an in-situ molded gasket using a silicone foam, comprising: measuring the liquid silicone composition, mixing the measured two-pack type liquid composition, and discharging the obtained mixture to a desired site. The present invention relates to a method for manufacturing an in-situ molded gasket, characterized in that the operation is performed by each of the following devices. 1) A metering / liquid feeding device for quantitatively pumping and feeding the silicone composition from a storage tank storing the liquid silicone composition 2) A liquid silicone foam composition fed from the above metering / liquid feeding device A mixing chamber to be housed, a cooling jacket provided on the outer periphery of the mixing chamber to circulate a cooling medium inside to cool the mixing chamber, and a pin-shaped, vane-shaped or screw-shaped outer periphery provided inside the mixing chamber. Mixing / discharging device comprising a rotary shaft having a protrusion of No. 1 and a discharge nozzle for discharging the mixture of the silicone composition mixed in the mixing chamber to a desired site. Will be specifically described.

As described above, the method for producing an in-situ molded gasket of the present invention comprises essentially measuring a two-pack type liquid silicone composition, mixing the measured compositions, and mixing the resulting mixture. Is discharged to a desired site, and is foamed and cured at room temperature or by heating at room temperature, and is mainly composed of the following two elements. In-Situ Foamable Silicone Foam Composition Device Having Function of Measuring, Mixing, and Discharging the Above Among the above-mentioned elements, the in-situ foamable silicone foam composition that satisfies the following requirements Required. I) Being liquid at room temperature II) Being able to be normally divided into two packaging types III) Weighing and mixing each component of the two divided packaging types, usually foaming and curing at ordinary temperature, It should have the property of accelerating the curing rate when heated as necessary. IV) The expansion ratio is 1.1 to 15 times, preferably 1.5 to 5 times V) Maintains the fluidity in the widest possible temperature range And a liquid state between −50 and 100 ° C. VI) Many of the cells in the foamed cured product are closed cells.
For example, the following A, B and C compositions can be mentioned.
Each of the compositions below is obtained by combining the respective basic composition components into a mixed component of two packages. A composition: basically (a) a polyorganosiloxane having at least two hydroxyl groups on average, (b)
A polyorganosiloxane having at least 3 Si-H groups, (c) a platinum catalyst and (d) a filler B composition: basically (a) having at least 2 hydroxyl groups on average Polyorganosiloxane, (b)
Polyorganosiloxane having at least 3 Si-H groups, (c) Polyorganosiloxane having at least 2 Si-Vi (vinyl) groups, (d) platinum catalyst and (v)
Composition consisting of filler C composition: (a) polyorganosiloxane having at least two Si-Vi (vinyl) groups, (b) polyorganosiloxane containing an MQ resin and having Si-Vi groups,
(C) Polyorganosiloxane having at least 3 Si-H groups, (d) Water or alcohol compound, (v) Platinum catalyst and (f) Filler composition It is also possible to add a retarder to a heat-curing type, or to add a thixotropic agent to impart non-fluidity. These compositions A to C can set the respective viscosities of the two packages by a liquid sending device, and the mixing ratio can be appropriately selected. Generally, the weight ratio is 1:
1 to 10: 1. The mixing time of the mixture of these two packages can be controlled by heating at 180 ° C. or lower after mixing and discharging.

Next, an apparatus having a function of measuring, mixing and discharging the second composition, which is the in-situ foamable silicone composition, will be described. FIGS. 1 and 2 show an example of an apparatus suitable for carrying out the method for manufacturing the in-situ molded gasket of the present invention. FIG. 1 shows a metering / liquid feeding apparatus and FIG. 2 shows a mixing / discharging apparatus. The above-mentioned metering and liquid sending device comprises a silicone composition storage tank 1 and a transport pump 2 for pumping out a liquid silicone composition from the silicone storage tank 1.
And weigh each pumped silicone composition,
A metering pump 4 for quantitatively feeding a predetermined amount of the silicone composition to a mixing / discharging device provided in the latter stage of the metering device, and the liquid feeding pipe provided in the liquid feeding pipe. The temperature adjusting device 4 adjusts the silicone composition passing through the passage to a desired temperature.

On the other hand, the mixing / discharging device is provided with a mixing chamber 9 around which a jacket 5 for circulating a cooling medium is installed, and a pin-shaped mixing chamber 9 provided inside the mixing chamber 9.
The rotor 7 is provided with a blade-shaped or screw-shaped protrusion 6, and the discharge nozzle 8 is provided at the bottom of the mixing chamber 9. According to this mixing / discharging device, the two kinds of liquid silicone compositions fed into the mixing chamber 9 via the liquid feeding conduit by the measuring / liquid feeding device are mechanically moved by rotating the rotor 7. The mixture can be mixed to form a homogeneous mixture, and the mixture can be discharged to a desired portion from the discharge nozzle 8 provided at the bottom of the mixing chamber 9. Less than,
The mixing chamber 9 and the rotor 7 will be described in more detail. (I) Cooling jacket 5 installed around the mixing chamber 9
Is to cool the inside of the mixing chamber 9 by circulating a cooling medium in the jacket. In this cooling operation, the liquid temperature of the mixed discharge liquid is remarkably raised (for example, raised to 30 ° C. or higher). The cooling medium need not be circulated if there is no significant temperature rise. (II) The clearance between the inner wall of the mixing chamber and the tip of the rotor (protrusion) is 1/1000 to 1/50, more preferably 1/500 to 1/100, with respect to the inner diameter of the mixing chamber. (III) The number of protrusions 6 can be set to an arbitrary number in the circumferential direction of the rotor, but generally 2 to 4 are preferable. (IV) The number of protrusions and the position of installation are set such that the volume of the rotor 7 is 5 to 60%, preferably 10 to 50% of the volume of the mixing chamber. (V) The length of the mixing chamber is 1/2 to 4 times, preferably 1 to 3 times the diameter. (VI) The rotation speed of the rotor is 50 to 4000 rpm, preferably 100
Set to ~ 3000 rpm. (VII) If necessary, a protrusion may be installed on the inner wall of the mixing chamber (see FIG. 2) so as not to contact the protrusion 6 of the rotor (see FIG. 2) to further improve the shear mixing force. However, the volume of these protrusions is the volume included in the rotor volume,
The condition of (IV) above shall be satisfied. (VIII) Before the silicone composition enters the mixing chamber, the silicone composition can be sufficiently mixed by premixing with a static mixer or the like, if necessary. As a result, the method for producing an in-situ foam type gasket according to the present invention can uniformly mix two packaging type liquid silicone compositions with extremely high shear mixing force, and thus cannot be used in the conventional method. The high viscosity silicone composition (for example, 30,000 cP or more / 25 ° C.) when the mixing ratio of the two liquids is more than 1: 1 (for example, 1: 5 or more), the non-fluid composition (that is, It is also applicable to thixotropic compositions) and the like, and the range of selection of raw materials used has become extremely wide.

Further, when the operation of pouring the silicone composition (mixed liquid) into a certain place or the operation of applying the silicone composition (mixed liquid) is performed, for example, when an automatic positioning device as shown in FIG. 3 is used. More effective. Also,
By using a robot, these operations can be accurately and uniformly repeated and applied at the same speed, and it is easy to keep the injection amount (application amount) of the silicone composition constant. As a result, variations in the size and weight of the molded product are reduced. Therefore, when the same product is mass-produced, it is possible to significantly improve the production efficiency and manufacture a molded product with good reproducibility.

[0009]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 [Preparation of Silicone Foam Agent] Silicone foam agents 1 and 2 were obtained with the following constituent components. Silicone foam agent 1: Room temperature curing type / fluid type package-1 ・ 100 parts by weight of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 15000 cP at 25 ° C ・ Viscosity at 25 ° C is 30 cP and both ends are trimethylsiloxy groups 10 parts by weight of polymethyl hydrogen siloxane which is blocked and the rest is methyl hydrogen siloxane unit: dimethyl siloxane unit = 3: 2 ・ 40 parts by weight of silica powder ・ Poly dimethyl siloxane having a viscosity of 200 cP at 25 ° C
15 parts by weight ・ (CH ₃ ) ₂ Si [OC {(CH ₃ ) ₂ } CH] ₂
0.05 parts by weight Package-2 ・ 100 parts by weight of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 15000 cP at 25 ° C ・ 10 parts by weight of α, ω-divinylpolydimethylsiloxane having a viscosity of 3000 cP at 25 ° C ・ Chloroplatinic acid 2 % IPA solution containing α, ω-dihydroxypolydimethylsiloxane as platinum atom relative to the total amount
Amount of 100ppm ・ 40 parts by weight of silica powder ・ Polydimethylsiloxane with a viscosity of 200cP at 25 ℃
15 parts by weight Package-1 and package-2 are mixed at a ratio of 1: 1 Silicone foam agent 2: Heat-curing type / non-fluid type Package-1-α, ω-dihydroxypolydimethyl with a viscosity of 15000 cP at 25 ° C 100 parts by weight of siloxane 10 parts by weight of polymethylhydrogensiloxane having a viscosity of 30 cP at 25 ° C., both ends blocked with trimethylsiloxy groups, and the rest of which is methylhydrogensiloxane unit: dimethylsiloxane unit = 3: 2. Powder 50 parts by weight ・ Polydimethylsiloxane with a viscosity of 200 cP at 25 ℃
15 parts by weight ・ (CH ₃ ) ₂ Si [OC {(CH ₃ ) ₂ } CH] ₂
1 part by weight ・ Hydrogenated castor oil 3 parts by weight Package-2 ・ 100 parts by weight of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 15000 cP at 25 ° C ・ α, ω-divinylpolydimethylsiloxane having a viscosity of 3000 cP at 25 ° C 10 parts by weight ・ IPA solution containing 2% of chloroplatinic acid As platinum atom based on the total amount of α, ω-dihydroxypolydimethylsiloxane
Amount of 100ppm ・ 45 parts by weight of silica powder ・ Polydimethylsiloxane with a viscosity of 200cP at 25 ℃
15 parts by weight The mixing ratio of the package-1 and the package-2 is 1: 1. The non-fluid type and the fluid type have the following characteristics. (1) Non-flowing type: This composition is a non-flowing type,
The one that stays in that position without flowing from the discharged position. Specifically, in the fluidity and non-fluidity measurement test of FIG. 4, a polystyrene cup (internal diameter 24 mm, volume 15 m
The composition in which l, which is the length that has flowed out 1 minute after the composition was filled in l) and the polystyrene cup was laid down, was less than 20 mm. (2) Flow type: This composition is a flow type and flows from its discharged position by its own weight. Foams and cures at room temperature. Specifically, in the same test as (1), X is 20
mm or more composition. Regarding the silicone foam agents 1 and 2 obtained as described above, the blade type screw shown in FIGS.
Gasket molding was carried out using the grooved type screw shown in FIG. The results are shown in Table 1 and Table 2.
Shown in. From these results, it is clear that in any case, the production method according to the present invention has a wide range of application to various production conditions and is excellent in operability / adjustment of cell size and balance of foam. In addition, this system is more effective when a heat-curable material is used.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

As described above, according to the method for producing an in-situ gasket of the present invention, essentially a two-pack type liquid silicone foam composition is weighed using a specific device, and after this weighing, The composition is mixed, and the resulting mixture is discharged to a desired site, and the discharged mixture is foamed and cured at room temperature, so that an in-situ foaming type gasket can be efficiently obtained at room temperature. This foaming can reduce the amount of raw materials used. Further, since the bubbles generated in the gasket by the foaming operation are closed cells, the airtightness of the gasket is extremely good.When measuring the gasket raw material, the physical properties of the product can be freely changed by changing the raw material composition. It has an excellent effect such that a gasket having a complicated shape can be produced by selecting a fluid composition as a gasket raw material which can be changed.

[Brief description of drawings]

FIG. 1 is a diagram showing a measuring and liquid feeding device suitable for carrying out the method for manufacturing an in-situ molded gasket of the present invention.

FIG. 2 is a mixing / discharging device suitable for carrying out the method for manufacturing an in-situ molded gasket of the present invention.

FIG. 3 is a schematic view showing the concept of manufacturing an in-situ molded gasket of the present invention using an automatic positioning device.

FIG. 4 is a schematic view showing a state of a fluidity / non-fluidity measurement test in Examples, (a) is a side view of a cup, and (b) is a diagram.
Is a view of the cup as seen from above.

[Explanation of symbols]

 1 Silicone Composition Storage Tank 2 Transport Pump 3 Metering Pump 4 Temperature Control Device 5 Cooling Jacket 6 Projection 7 Rotor 8 Discharge Nozzle 9 Mixing Chamber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location F16J 15/10 W 8207-3J // B29K 83:00 105: 04 B29L 31:26 4F C08L 83: 04 (72) Inventor Kunio Ito 6-23-1, Roppongi, Minato-ku, Tokyo Inside Toshiba Silicon Co., Ltd.

Claims (1)

[Claims] 1. A process in which essentially two-pack type liquid silicone composition is weighed, the weighed compositions are mixed, and the resulting mixture is discharged to a desired site to foam and cure in situ. A method for producing an in-situ molded gasket using a silicone foam, comprising: measuring the liquid silicone composition, mixing the measured two-pack type liquid composition, and discharging the obtained mixture to a desired site. A method for manufacturing an in-situ molded gasket, characterized in that the operation is performed by each of the following devices. 1) A metering / liquid feeding device for quantitatively pumping and feeding the liquid silicone composition from a storage tank in which the liquid silicone composition is stored. 2) A liquid silicone foam composition fed from the above metering / feeding device. A mixing chamber to be housed, a cooling jacket provided on the outer periphery of the mixing chamber to circulate a cooling medium inside to cool the mixing chamber, and a pin-shaped, vane-shaped or screw-shaped outer periphery provided inside the mixing chamber. Mixing / discharging device having a rotating shaft having the protrusions and a discharging nozzle for discharging the mixture of the silicone composition mixed in the mixing chamber to a desired portion.