JPH06117543A - Manufacture of foam body by screen printing method - Google Patents

Abstract

PURPOSE:To provide a method by which coating on desired shapes can be accomplished simply and rapidly and in large quantities without requiring an expensive NC system and moreover, a fixed quality without unevenness can be obtained. CONSTITUTION:This is the manufacture of a foam body by means of a screen printing method featuring a method in which a main agent and a hardening agent are prepared separately, and the respective predetermined quantities of the main agent and the hardening agent are fed into a mixing chamber, and these main agent and hardening agent thus fed are mixed, and next, a mixture of these agents delivered from the mixing chamber is printed on a matter to be coated by means of the screen printing method, and then, a printed matter is heated and foamed. The mixture of the main agent and the hardening agent is printed by using a screen printing device. A matter 42 to be printed is placed on a stand 41, and a printing screen 44 provided at a frame 46 is placed over it. Resin patterns 43 are formed at this screen 44. As for printing, a foaming mixture 45 is placed on the screen 44, and printing is conducted by moving a squeegee 47 in an arrow direction, then a coated matter of a desired shape can be obtained according to a mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foam by a screen printing method, and more specifically to a foam by a screen printing method which can be quickly processed into a complicated shape and can obtain a good foam. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art Conventionally, a foam has been formed in a sealing portion in order to achieve air-tightness and liquid-tightness with the outside such as a lid for various electric equipment parts and various other containers, a waterproof case for automobiles, and the like. As shown in FIG. 7, a gasket foam 22 is formed on the lid 31 of the waterproof case, for example, around the lid.

FIG. 8 is a sectional view of FIG. 7, and the gasket foam 33 has a large number of closed cells. There are various methods for forming such a foam, but a nozzle is usually used, and the foamable composition is discharged along a desired shape as shown by reference numeral 32 in FIG.

[0004]

However, when a desired shape is directly applied using a nozzle, the applied line becomes thick or thin due to the difference in the discharge amount from the nozzle, and the line tends to vary. It turns out to be a problem. Further, in order for the nozzle to operate along a desired shape, an NC device is required, which is costly, and there is a problem that the coating speed by the nozzle is slow and productivity is not sufficient. Further, there is a problem that the scanning method using a nozzle takes a long time to form a complicated shape and is not preferable in terms of economical efficiency.

Therefore, as a result of various studies on the above-mentioned problems, the present inventors were able to apply a complicated shape easily, in large quantities, and quickly by using the foamable mixture by applying the screen printing method. Further, they have found that a product having a constant quality without variation can be obtained, and the present invention has been completed based on this finding.

Therefore, it is an object of the present invention to provide an expensive NC
It is an object of the present invention to provide a method for producing a foam by a screen printing method, which can easily and rapidly apply a large amount in a desired shape without using a device, and can obtain a product having a constant quality without variation. .

[0007]

The above object of the present invention can be achieved by the following methods (1) to (5) for producing foams.

(1) A base material and a curing agent are separately prepared, and a predetermined amount of each of the base material and the curing agent is sent into a mixing chamber, the supplied base material and the curing agent are mixed, and then the mixture is sent out from the mixing chamber. A method for producing a foam by a screen printing method, comprising: printing a mixture of the main ingredient and a curing agent on a coated object by a screen printing method, and then heating the printed material to foam.

(2) The screen printing method according to the above item 1, wherein a gas is introduced into at least one of the main component and the curing agent before being sent into the mixing chamber in a predetermined amount. For producing a foam according to.

(3) The method for producing a foam by the screen printing method according to the above item 1 or 2, wherein a mixture of the mixed main component and curing agent is preheated.

(4) The method for producing a foam by the screen printing method described in the above item 1, 2, or 3, wherein a gas is mixed into the preheated mixture.

(5) When the mixing is carried out by means of a dynamic mixer, the mixing chamber is cooled, and the screen printing method according to the above-mentioned item 1, item 2, item 3 or item 4 is used. Method for producing foam.

(6) The first item, the second item, the third item, characterized in that the mixing is performed by a static mixer.
A method for producing a foam by the screen printing method according to claim 4 or 5.

The present invention will be described in more detail below. In the present invention, it is preferable to mix the main agent and the curing agent, which have been sent to the mixing chamber by a predetermined amount, with a dynamic mixer in order to perform the mixing densely. When mixing with a dynamic mixer, the temperature rise in the mixing chamber is suppressed by mixing while cooling to suppress foaming of the mixture. The advantage of using a dynamic mixer is to ensure reliable mixing in a short time.

In the present invention, when a static mixer is used as a mixer, a cooling device is not required,
A heat-foamable silicone composition was obtained by uniformly mixing the main agent and the curing agent with a mixer, but substantially no foaming occurred even during mixing by such stirring, and after printing,
By heating with a heating device, foaming is performed in a short time to obtain a foam.

Further, after the mixed mixture of the main agent and the curing agent is sent out from the mixing chamber, the mixture is preheated,
By printing at the sealing location, the heat-foaming of the mixture is promoted, and the time required for foam formation can be shortened and good results can be obtained for foam formation.

Further, according to the present invention, a dense and uniform foamed product can be obtained by discharging the mixed mixture of the main component and the curing agent, which is preheated and then mixed with the gas, especially immediately before or after the mixing. To be

In the present invention, introducing a gas into the main agent and / or the curing agent together or in any one of them is a preferable means for promoting the foaming of the mixture applied by printing. Any means such as a method of blowing a gas, a method of blowing a gas into the main agent and the curing agent using a pipe, a method of mixing from the surface of the main agent or the curing agent by stirring, or the like may be used. This is a method of mixing from the surface.

Examples of the gas include inert gas, air, nitrogen and the like. It is preferably air. The foam produced in the present invention is not particularly limited, and examples thereof include foams of cellulose acetate, epoxy resin, phenol resin and the like, urethane foam, silicone foam and the like.

Among them, the silicone foam is preferably used because it is excellent in heat resistance, cold resistance, insulation properties, and also excellent in weather resistance, water resistance and safety and hygiene. The silicone foam is composed of an organopolysiloxane compound,
It is formed by the reaction of the base compound and the curing agent.

As the main agent, it is preferable to use an organopolysiloxane having a substituent such as a silanol group or an alkenyl group in the molecule. As the curing agent used in the present invention, for example, organohydrogenpolysiloxane is preferable.

As the curing catalyst, generally known curing catalysts such as platinum catalysts, organic tin catalysts, aminoxy catalysts and the like are used. In the present invention, the mixing ratio of the main agent and the curing agent,
It is used in a wide range, but preferably the amount of curing agent added is
3 to 1 equivalent of the reactive group (eg, alkenyl group) in the main agent
It is 100 equivalents, and more preferably 20 to 70 equivalents.

In the present invention, a mixer is used for mixing the main agent and the curing agent. As the mixer, either a dynamic mixer or a static mixer may be used, but a dynamic mixer is preferable. is there. This dynamic mixer has a desired number of projections on its inner wall, and a stirring blade is sewn between them to rotate.

Various types of stirring blades may be used for the mixer, for example, published by Maruzen, edited by Jiro Shiokawa, "Kirk-Osmer Chemistry Dictionary," page 506, right column, line 1 to page 508, right column, The one described in line 10 is used.

Further, the dynamic mixer is provided with a protrusion on the inner wall, and the dynamic mixer is
A stirring device having at least two stirring blades each having a shaft extending in the cross direction on its axis is arranged in the central portion, and the stirring blades are arranged between the protrusions in the height direction so as to rotate. Has become.

In the present invention, when a dynamic mixer is used for mixing the main agent and the curing agent, the mixture is cooled, but this cooling means is not particularly limited.
A cooling medium may be placed in the mixing chamber, or a cooling medium may be installed around the mixing chamber. Further, the main agent and the curing agent may be cooled before being introduced into the mixer. The cooling temperature depends on the type of the foamable composition, but is 0 ° C to 25 ° C, preferably 5 ° C to 15 ° C.

As the static mixer used in the present invention, those commonly used in the technical field of mixing are used. In this static mixer, the turbulent flow-generating elements are stacked in several stages in series. The present invention is characterized in that the liquid to be mixed is allowed to pass therethrough, and because the mixing portion is in a stationary state, power for mixing is not necessary and heat is not generated by mixing. It is preferably used for.

As the above-mentioned element, for example, multi-stage shelves or spiral blades are continuously provided by making point contact with each other, and a mixture to be mixed while two liquids flow down or plates alternately perforated are provided in multi-stages. There are those in which the two liquids are mixed while passing through the holes, and those in which the two liquids are applied and mixed to a disc that rotates slowly.

More specifically, JP-B-44-8290, JP-A-58-128134, JP-A-59-166232, JP-A-60-139324, JP-A-62-42728, and JP-A-62-42732.
-27029, 62-57634, 62-87.
No. 232, No. 62-140631 and the like.

The mixture of the main agent and the curing agent, which is mixed while being cooled in the mixing chamber, is applied to the screen portion of the screen printing apparatus by the mixture supply member through the liquid feeding hose and is printed by squeegeeing. The mixture is applied to the plate after the gas is mixed in immediately before or immediately after the mixture is applied to the screen portion by the mixture supply member.

As the mixture supply member used when the mixture is applied to the plate surface, it is preferable that a plurality of nozzles are arranged side by side in the width of the screen or have a so-called divergent shape having a width close to the width of the screen. . The number of nozzles depends on the size of the printing plate, but it is preferable to arrange 1 to 5 nozzles in parallel.

The mixture applied to the plate surface is printed by sliding under pressure with a squeegee, or the mixture is preheated by applying heat, and the heated mixture is discharged from a nozzle. Immediately before or immediately after being mixed with gas, it is applied to the printing plate and printed.

Further, the gas may be mixed in the mixture immediately before being discharged from the nozzle and applied to the member to be coated, or at a mixing position other than immediately before being discharged from the nozzle. Not limited to the nozzle portion, it may be a portion of the liquid feeding hose.

When a nozzle is used, the gas mixing means preferably has at least two liquid discharge surfaces at the tip of the nozzle.
It is preferable that the number of discharge holes, that is, the number of pinholes, be 2 to 8, preferably 3 to 5 depending on the size of the gasket at the application site. Is.

When the mixing chamber is fixed, a liquid supply hose may be used to connect the nozzle to the nozzle. When a liquid feeding hose is used, the preheating device may be installed so as to wrap the liquid feeding hose. The pre-heating temperature can be determined in consideration of the pot life of the foamable composition, and it is preferable to heat the pre-heating temperature to an extent not exceeding the foaming temperature of the foamable composition.

When the foamable mixture is not applied to the plate surface through the nozzle, after mixing the gas into the foamable mixture,
Apply to print. The screen printing method used in the present invention is not particularly limited, and a conventionally known device is used, and an example thereof is flat printing,
There are curved surface printing and winding printing.

The screen plane printing will be described in more detail. FIG. 4 shows a schematic diagram of a screen printing apparatus used when the screen printing method used in the present invention is applied. The printing screen 44 placed and placed on the frame 46 is placed thereon. A resin pattern 43 is formed on the screen 44.

A resin pattern 43 is formed on the screen 44.
As a method for forming the film, a method well known in the technical field of screen printing is usually used. Printing is on screen 4
When the foamable mixture 45 is placed on 4 and the squeegee 47 is moved in the direction of the arrow for printing, a coating having a desired shape can be obtained according to the mask.

Then, the coating material formed of the foamable mixture formed in this way requires a long time to foam in this state, so that it is heated to accelerate the foaming. Foams to form a foam. For example, at least 60 ° C within 5 minutes, and at 80 ° C 3
It is preferable to foam within minutes.

Although various heating modes are conceivable, there are a method of applying heated air, a method of passing or placing in a heated room, a method of passing through a dome having a heating device, and the like. Includes direct heating using a heater for nichrome wire, infrared rays, far infrared rays, and indirect heating for sending heated air.

The method for producing a foam by the screen printing method of the present invention is applied to various fields, for example, packing for gas water heaters, water heaters, waterproof cases for electrical equipment, seals for required parts of automobiles, and construction. Used for applications such as waterproofing aluminum sashes, separating walls, soundproofing, preventing noise generation, and preventing vibration.

[0042]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Example 1 FIG. 1 is a flow sheet showing a method for producing a foam of the present invention, and FIG. 2 is a schematic diagram of an apparatus for carrying out the method of the present invention.

In FIGS. 1 and 2, the main body tank 1 is
Liquid A of Chemisir S-251 as a main agent (organopolysiloxane having an alkenyl group as a main component, a catalyst,
It contains a reaction suppressor etc., made by Chemtech),
In addition, in the curing agent tank 1, as a curing agent, ChemiSeal S-
251 solution B (containing organohydrogensiloxane as a main component, manufactured by Chemtech) is added. The liquid A is black and has a viscosity (25 ° C.) of 86000 cp and a specific gravity of 1.11, and the liquid B is white and has a viscosity (25 ° C.) of 28,000 cp and a specific gravity of 1.12. Both are slowly stirred so that each liquid becomes homogeneous.

The homogeneous liquids A and B thus obtained
The liquid is measured with a metering pump, and a predetermined amount (a sufficient amount for coating) is sent to the mixing chamber of the mixing C at a ratio of 1: 1 to mix the liquids A and B so that they are sufficiently uniform. . Mixing is done with a dynamic mixer 1 shown in cross section in Figure 3a.
0, in which the mixing chamber is water-cooled so that the temperature of the mixture becomes 7 ° C. in order to prevent the temperature from increasing with stirring. As shown in FIG. 3a, the mixer 10 has protrusions 34 on the inner wall thereof, and the stirring blades 33 rotate in this gap.

Then, this mixture is sent to the liquid sending hose 23 by the D liquid sending hose portion, and at the E liquid supplying member portion attached to the tip of the liquid sending hose 23,
Applying process H from the discharge nozzle 13 by screen printing
Is discharged to the scooter of the printing device. Air is mixed into the mixture immediately after being discharged from the tip 14 of the discharge nozzle. The inclusion of this air results in a better foam. The mixture thus discharged to the screen portion is squeegeeed and printed on the member to be coated.

The mixture cooled by the mixture C is heated by the preheating device 12 while moving in the liquid feeding hose 23 so that it easily foams during heating. The preheating temperature is such that the mixture reaches 40 ° C.

In the coating process of H by the screen printing method, the members are aligned with F and the coating position is set with G. In the screen printing process H described above, FIG.
Print using the screen printing device shown in. That is, in FIG. 4, the member to be coated 42 is set to the coating position G, the frame 46 with the screen 44 is placed thereon, and the liquid supply member 13 (see FIG. 2) is placed on the screen 44.
Printing is performed by discharging the foamable composition 45 from the four nozzles 14 of the reference) and then sliding with the squeegee 47.

The member to be coated thus coated by the screen printing method is set in the heating furnace I, then introduced into the heating furnace J and heated with the heating K at a heating temperature of 80 ° C. to foam in 2 minutes. Was completed and a foam was obtained. After the foaming of L is completed, the member is taken out M.

By using the screen printing method as described above, a large amount of coating material can be obtained easily, quickly and in large quantities.
This foam is densely and uniformly foamed, but when it is further applied onto the screen through the nozzle, it is further sufficiently foamed because air is mixed therein. Liquid supply member 1
Instead of using a plurality of nozzles, as shown in FIG. 6, a pipe having a shape in which the tip of the pipe is widened toward the end is used.

The opening 15 of the tube may have a slit-like gap, and a plurality of holes 151 may be provided in the opening surface as shown in FIG. 6b. Providing a plurality of holes 151 as in the latter case is preferable in that air is mixed at the time of discharging the liquid and a good foam is obtained at the time of foaming. More preferably, the shape 1 in which holes are collectively provided as shown in FIG.
A better foam can be obtained by providing a plurality of 52.

Example 2 Except that air was introduced into the main body tank containing the solution A and the curing agent tank containing the solution B used in Example 1 to form the solutions A and B mixed with air. A foam was produced in the same manner as in Example 1. This foam was more dense and uniform, and was a good foam.

Example 3 A foam was produced in the same manner as in Example 1 except that the mixture obtained by mixing in Example 1 was preheated to 80 ° C. The resulting foam was a good foam that foamed in a short time and was dense and uniform.

Example 4 Foaming was carried out in the same manner as in Example 1 except that the mixing of Example 1 was carried out using the mixer having the structure shown in FIG. 5 as the static mixer shown in FIG. 3b. Manufactured body. This static mixer 50 is formed by laminating six spiral blades 51 integrally formed in a short passage tube 52 as one unit. Even when the foamable composition mixed using this static mixer 50 was used, the obtained foam was dense and uniform, and was a good foam.

Example 5 A foam was produced in the same manner as in Example 1 except that it was applied on a screen without passing through a nozzle in Example 1. The obtained foam was dense and uniform, and was a good foam.

[0056]

INDUSTRIAL APPLICABILITY According to the present invention, an expensive NC is obtained by mixing a main agent and a curing agent, and then printing the mixture of the mixed main agent and the curing agent sent out from the mixing chamber using a screen printing method. It is possible to easily and quickly apply a large amount in a desired shape without using a device, and obtain a product having a constant quality with no variation. Further, according to the present invention, it is possible to produce a dense foam by mixing gas in advance with the main agent and the curing agent.

The present invention, when printed by the screen printing method after passing through the following steps, has the following excellent effects. (1) In the present invention, it is preferable to mix the main agent and the curing agent, which have been sent to the mixing chamber by a predetermined amount, with a dynamic mixer in order to perform the mixing densely. When mixing with a dynamic mixer, the temperature rise in the mixing chamber is suppressed by mixing while cooling to suppress foaming of the mixture. The advantage of using a dynamic mixer is to ensure reliable mixing in a short time.

(2) Further, after the mixed mixture of the main agent and the curing agent was sent out from the mixing chamber, the mixture was preheated and / or discharged while being preheated to be applied to the sealing portion. Later foaming of the mixture is promoted, which can reduce the time required for foam formation and good results for foam formation. (3) In addition, according to the present invention, a dense and uniform foamed body can be obtained by discharging gas while mixing or mixing gas before the mixture of the mixed main agent and curing agent is discharged from the nozzle, particularly immediately before or immediately after. . Therefore, according to the manufacturing method of the present invention, it is possible to achieve excellent effects that combine the above effects.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a method for producing a foam.

FIG. 2 is a perspective view showing an apparatus for producing a foam by a screen printing method used in the present invention.

FIG. 3A is a sectional view showing an example of a dynamic mixer, and b is a sectional view showing an example of a static mixer.

FIG. 4 is a sectional view showing a screen printing apparatus used in the present invention.

FIG. 5 is a cross-sectional view showing the structure of a static mixer used in the present invention.

FIG. 6 is a view showing an embodiment of a liquid supply member used in the present invention. a is a perspective view showing the whole liquid supply member, b is a plan view of an opening surface, and c is a plan view of another embodiment of the opening surface.

FIG. 7 is a perspective view showing a gasket foam provided on the lid.

FIG. 8 is a cross-sectional view of the gasket foam provided on the lid.

[Explanation of symbols]

1 Main Agent Tank 31 Lid 2 Curing Agent Tank 32 Gasket Foam 3, 4, 9 Motor 33 Stirring Blade 5, 6 Automatic Measuring Discharge Pump 34 Protrusion 7, 8 Liquid Feed Hose 35 Static Mixer Nozzle 10 Mixer 36 Spiral Groove 11 cooler 41 units 12 preheating device 42 coating object 13 liquid supply member 43 resin pattern 14 nozzle needle 44 screen 15 opening surface 45 foaming composition 16, 17 cooling hose 46 screen frame 18 cleaning liquid hose 47 squeegee 19 end spread Part 50 Mixer 20, 21, 22 Cock 51 Spiral blade 23 Liquid feed hose 52 Passage pipe 24 Motor shaft 53 Fluid passage 25 Nichrome wire 151 hole 26 Tape-like long object 152 Hole group 27 Temperature controller

Claims (6)

[Claims] 1. A base material and a curing agent are separately prepared, and a predetermined amount of each of the base material and the curing agent is sent into a mixing chamber,
It is characterized in that the main agent and the curing agent sent out are mixed, and then the mixture of the main agent and the curing agent sent out from the mixing chamber is printed on an object to be coated by a screen printing method, and then the printed material is heated to foam. And a method for producing a foam by a screen printing method. 2. At least one of the base material and the curing agent is fed into the mixing chamber before being delivered in a predetermined amount.
2. A method for producing a foam by the screen printing method according to claim 1, wherein gas is introduced into one side. 3. The method according to claim 1, wherein a mixture of the mixed main agent and curing agent is preheated.
A method for producing a foam by the described screen printing method. 4. The method for producing a foam by the screen printing method according to claim 1, wherein gas is mixed into the preheated mixture. 5. The foam produced by the screen printing method according to claim 1, wherein the mixing chamber is cooled when the mixing is performed by means of a dynamic mixer. Manufacturing method. 6. The method for producing a foam by the screen printing method according to claim 1, claim 2, claim 3, claim 4 or claim 5, wherein the mixing is performed by a static mixer.