JPH07117064A - Formation of foam for sealing material - Google Patents

Abstract

PURPOSE:To dispense with the use of an org. solvent and to prevent the short- time curing in a mixing device by adding a foam stabilizer and a thickener to an one-pack type curable synthetic resin emulsion to mechanically foam the emulsion and directly emitting the foamed emulsion into a groove part desiring the formation of a sealing material. CONSTITUTION:A foam stabilizer and a thickner are added to an one-pack type curable emulsion to mechanically foam the emulsion. At this time, it is pref. to stirr the emulsion for 1-3min in the number of rotations of 500-2000rpm using a high speed stirrer. By this method, uniform and stable fine foams can be formed. This foamed emulsion is injected into a groove part desiring the formation of sealing foam to be dried.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a foam for a sealant using a mechanically foamed material by adding a sealing material, a foam stabilizer and a thickener.

[0002]

2. Description of the Related Art Synthetic resins can be molded and processed by various methods such as compression molding, injection molding, molds, extrusion molding, blow molding, lamination molding, foaming, etc. Among the molded products, the proportion of foamed molded products is increasing. Currently available general-purpose foamable synthetic resin materials include a two-component foamable resin material and a heat-foamable resin material. The heat-foamable resin material is a thermal decomposition type thermoplastic resin. It is general to add the foaming agent of.

The properties of synthetic resin foams depend on the synthetic resin composition used as the material, the expansion ratio and the cell structure, and in terms of strength, heat insulation, sound absorption characteristics, buffering properties, etc. It's very different. In particular, because of its excellent heat insulating properties and sound absorption properties, it is used for various purposes such as sealing materials for construction or automobiles, clothing miscellaneous goods such as the formation of letters and patterns on T-shirts, and cosmetic puffs. .

[0004]

However, in the case of the two-component foamed resin material, there is a problem in that the degree of foaming varies due to variations in the mixing ratio of the liquid or the reaction temperature, and the physical properties of the foam are not constant. there were. Further, even in the case of a heat-foamable resin material, when heated after being discharged into a mold, a difference in foaming ratio is likely to occur between the material surface portion where heat is easily transmitted and the interior portion where heat is difficult to be transmitted, and a uniform foam is formed. It is difficult and has the problem that the physical properties are not constant like the two-component foamed resin material. Further, in the two-component foamed resin material and the heat-foamable resin material as described above, an organic solvent is used as a solvent. However, this is because the resin material is easily hardened in the mixing device, and the device is used during intermittent operation. This is because the cleaning is essential. Further, when cleaning the apparatus, these resin materials are not dissolved in water, so that an organic solvent has to be used, and there is a problem in maintaining a good working environment.

[0005]

Therefore, the present inventors have
As a result of intensive studies to solve the above problems, the present invention has been completed. That is, in the present invention, a foam stabilizer and a thickener are added to a one-part curable synthetic resin emulsion, mechanically foamed, and directly discharged into a groove portion to be formed,
It is a method of forming a foam for a sealing material by drying.
The present invention is characterized in that, when performing mechanical foaming, the foaming is carried out for 1 to 3 minutes at a rotation speed of 500 to 2000 rotations / minute using a high-speed stirrer. In addition, when directly discharging to the groove portion to be formed, the sealing material foam is discharged at a discharge amount of 50 to 200 g / min.

The present invention will be described in detail below. The one-component curable synthetic resin emulsion is an emulsion in which a one-component curable synthetic resin is dispersed in a solvent in which the synthetic resin is insoluble. The emulsion includes a water-oil emulsion (w / o type emulsion) when the continuous phase is water, and an oil-
There are two types of water emulsion. Generally, it is not possible to spontaneously form an emulsion, and a third component is added in order to form a stable emulsion. This third component is called an emulsifier, and generally a surfactant is used. It

Here, as the synthetic resin usable in the synthetic resin emulsion, polyvinyl chloride, polyethylene,
Examples include polypropylene, ethylene-vinyl acetate copolymer resin, styrene, polyurethane, ABS resin, polyvinyl formal, fibrin acetate, acrylic resin, epoxy resin, phenol resin, urea resin, silicone resin, and the like, but polyurethane, acrylic resin , Silicon resin and the like are preferable. This is because these resins are excellent in elasticity, light resistance, heat resistance and the like. Typical one-part curable synthetic resin emulsions are trade names Superflex E-4000 and Acrylic Set 330E,
They are marketed by Daiichi Kogyo Seiyaku Co., Ltd. and Nippon Shokubai Co., Ltd., respectively.

The continuous phase of the emulsion used here is preferably water or the like. A synthetic resin emulsion using the above resin and a continuous phase is prepared by mixing 30 to 60% by weight of a synthetic resin with a continuous phase such as water.

The foam stabilizer used in the present invention can be rephrased as a foaming agent, and means an additive which has a strong influence on the interfacial tension of the foam liquid forming the foam. The foam stabilizer can be appropriately selected depending on the type of synthetic resin emulsion used, foaming method, and the like. Generally, a foam stabilizer based on methylpolysiloxane is used. It is also possible to use a commercially available surfactant, for example, palm oil alcohol sodium sulfate, sodium alkyl benzene sulfonate, higher fatty acid monoglyceride sodium sulfate, alcohol polyglycol sulfate sodium salt, palm oil fatty acid potassium salt. Examples include soap and the like. In particular, sodium stearate, sodium alkyl sulfonate, and higher fatty acid amide are preferable. The reason for this is that stable fine bubbles can be obtained.

The amount of the foam stabilizer added to the one-part curable synthetic resin emulsion is preferably 2 to 10 parts by weight with respect to 100 parts by weight of this emulsion. This is because if the amount of the foam stabilizer added is too small, the foaming will be insufficient, and if it is too large, molecular association will occur and the foamability will deteriorate.

The thickening agent means an agent which increases the viscosity of the emulsion and is added as a protective colloid. Thickeners are roughly classified into those of a solvent dispersion type and those of a water dispersion type. Examples of the solvent dispersion type include metal soaps such as Al-stearate and Zn-stearate, and silica gel such as silica gel. Examples include acidity, organic bentonite, polymerized oil, and the like. Examples of the water-dispersible system include inorganic materials such as silicic acid, bentonite and the like, methyl cellulose, cellulose derivatives such as CMC, proteins such as casein and caseinate, alginate and polyacrylate. Here, the water-dispersed thickeners such as ammonium polyacrylate, sodium polyacrylate, and polyacrylamide are preferable. The amount of the thickener added to the one-part curable synthetic resin emulsion is 10
It is preferably 0.5 to 50 parts by weight with respect to 0 parts by weight. This is because if the addition amount of the thickening agent is too small, the viscosity of this emulsion is low and the bubbles are crushed immediately, while if it is too large, the viscosity becomes too high and it becomes difficult to form bubbles. In addition, there are cases where the water resistance of the product decreases.

Mixing of the above components and mechanical foaming are preferably carried out as follows. This will be described with reference to FIG.
The above components are separately put in the tanks 20 to 24 of the apparatus shown in FIG. 1, and the pump 2 provided at the bottom of each tank
While adjusting 6 to 30, it is introduced into the mixing chamber 10 and the stirrer 12
The mixture is rotated and stirred, and the mixed sealing material composition is mechanically foamed to foam. The apparatus used here is provided with the stirring bar 12 in the mixing chamber 10 as described above,
Any material can be used as long as it can mechanically mix air into the above material to generate bubbles, and for example, a high-speed stirrer such as a disperser or an Oaks mixer can be used. Also,
When stirring and foaming at the construction site, it is advisable to use a small high-speed agitator. The foam for sealing material thus foamed may be agitated in the mixing chamber 10 of the apparatus with a nozzle as described above and extruded from the nozzle 16 provided in the bottom portion 14 of the mixing chamber 10. Alternatively, the mixture may be stirred in a small container, transferred to a device such as a squeezing bag, and squeezed into the groove portion 42 in which the foam for the sealing material is desired to be formed. Each component used in the foam for a sealing material is 1 to 500 rpm at 1 to 500 rpm using the above high-speed stirrer.
Mix and stir for 3 minutes to foam. The stirring condition is set in this range because uniform and stable fine bubbles can be formed.

After the composition for the sealing material is sufficiently foamed, it is directly discharged from the nozzle 16 provided in the bottom portion 14 of the mixing chamber into the sealing groove portion 42 where the sealing material is to be formed. The groove portion 42 shown in FIG. 1 is a portion where an automobile headlight main body as an article to be coated 40 and a sealing material (not shown) for hermetically holding a glass cap are formed,
It is a recess formed on the surface of the article to be coated 40 with a certain depth and width. In the method of the present invention, a foam stabilizer and a thickener are added to the one-part curable synthetic resin emulsion, the sealing material is mechanically foamed, directly discharged into a groove portion to be formed, dried and sealed in the groove portion 42. The foam material 44 is formed. The diameter of the nozzle and the width of the groove are not particularly limited, but it is preferable that the diameter of the nozzle is smaller than the width of the groove by about 2 to 5 mm. The reason is that if it is too small, it takes time to discharge, and if it is too large, the foam easily sticks out from the groove portion and the workability deteriorates. As an example of the article to be coated having the groove portion in which the sealing material is desired to be formed, a tight seal container, various packings and the like can be mentioned in addition to the packing portion of the automobile lamp shown in FIG. Among these, the packing part of the automobile lamp and the like are particularly preferable.

When the foamed sealing material composition is discharged, the article to be coated 20 is placed so that the entire groove 42 is horizontal, and the tip 16a of the nozzle 16 is provided along the groove 42.
The groove 4 with the composition for a sealing material foamed while moving
Directly discharge to 2. With the nozzle 16 fixed, the article to be coated 20 is moved so that the groove portion 42 becomes horizontal, and the groove portion 42 is moved.
Alternatively, the foam may be discharged. The discharge amount of the foamed sealing material foam varies depending on the capacity of the device, but is 50
~ 200 g / min is preferred. The reason is that if the amount is too small, the productivity is poor, and if the amount is too large, it is difficult to adjust the foam shape.

As described above, the sealing material composition discharged into the groove portion 42 formed in the article 20 is dried to form the sealing material foam 44. Drying may be performed by any method such as room temperature, heating and cooling. For example, when the composition for a sealing material is heated during foaming, the composition is directly discharged into the groove and then cooled and dried, and
You may heat if you want to dry in a short time. The heat resistance of the article to be coated, the time required for drying, and the like are taken into consideration to appropriately select.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Production Example) (1) Foam for Sealing Material Using Urethane Emulsion As a urethane emulsion, Superflex E
-4000 (PTMG-HMDI type, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 100 parts by weight, F242T (dimethylpolysiloxane type, manufactured by Shin-Etsu Silicone Co., Ltd.) 5 as a foam stabilizer
2.5 parts by weight of Latekoll AS (ammonia acrylate type, manufactured by BASF) as a thickening agent are mixed and stirred for 3 minutes at 500 rpm using Disper (manufactured by Tokushu Kika Kogyo Co., Ltd.) to foam. It was This foaming composition for a sealing material was directly discharged from a nozzle having a diameter of 3 mm into a groove portion having a width of 5 mm, and was heated and dried at 120 ° C. for 5 minutes in a gear oven to form a foaming material for a sealing material (Example 1).

(2) Foam for sealing material using acrylic emulsion As acrylic emulsion, acrylic set 330
E (acrylic acid-based polymer mixture, manufactured by Nippon Shokubai Co., Ltd.)
100 parts by weight, SH-190 as a foam stabilizer (manufactured by Toray Dow Corning Co., Ltd.) 1 part by weight, Alon A as a thickener
5 parts by weight of -20 L (sodium polyacrylate type, manufactured by Toagosei Kagaku Co., Ltd.) were mixed and stirred at 1000 rpm for 2 minutes using Disper (manufactured by Tokushu Kika Kogyo Co., Ltd.) to foam. The foaming composition for a sealing material was directly discharged from a nozzle having a diameter of 5 mm into a groove portion having a width of 8 mm and dried at 25 ° C. for 30 minutes in a room temperature atmosphere to form a foaming material for a sealing material (Example 2).

(3) Two-component reactive foam A liquid is 100 parts of polyether polyol G-5000.
Parts by weight, 2 parts by weight of ethylene glycol, 0.5 parts by weight of water as a foaming agent, 2 parts by weight of silicone foam stabilizer F242T (Shin-Etsu Silicone Co., Ltd.), amine catalyst TEDA
1 part by weight of L-33 (manufactured by Tosoh Corporation). Solution B consists of polymeric MDI. A two-component urethane foam resin having the above composition was reacted at an A: B ratio of 100: 25 to produce a test piece having the same size as that of the following example (Comparative Example 1). The two-component urethane foam resin having the above composition was reacted at an A: B ratio of 100: 30 to prepare a test piece having the same size as that of the following example (Comparative Example 2).

(Evaluation of Physical Properties) Foams of Examples 1 and 2 of the present invention foamed as described above and Comparative Examples 1 and 2
The composition of (1) was discharged to a length of 40 cm, a width of 40 cm, and a thickness of 5 cm, and dried to obtain a test piece for evaluation of physical properties.
It was measured and evaluated by the following method. Hardness is JIS K64
It measured according to 01. Compressive residual strain is JIS K64
It measured according to 01. The measurement results are shown in Table 1.

[0021]

As shown in Table 1, the foams of Examples 1 and 2 formed by mechanically foaming exhibited hardness, density, and compressive residual strain within the target values, and were used as sealing materials. A foam having good physical properties could be obtained. On the other hand, in the two-pack type reactive foams of Comparative Examples 1 and 2, the physical properties may be greatly different due to a slight difference in the mixing ratio of the A liquid and the B liquid, and the physical property values may be outside the target range. It has been shown. It was considered that this variation was due to the mixing ratio of the liquid A and the liquid B, the ambient temperature, and the like. From the above, it has been clarified that according to the method for forming a foam for a sealing material of the present invention, a foam having good physical properties as a sealing material can be obtained. It was considered that the above-mentioned high hardness and small compressive residual strain of the foam for a sealing material obtained by the method of the present invention were due to mechanically foaming one liquid. That is, there is no change in the physical properties due to the mixing ratio and reaction temperature as in the case of the two liquids, and because of mechanical foaming, there is a temperature difference due to the thermal conductivity relationship between the surface of the object and the inside like heating foaming. This is because there is no influence on the foaming process. Therefore, it has a high sealing effect and can withstand long-term use as compared with conventional sealing materials.

[0023]

As described above, since the foam for a sealing material of the present invention is a single liquid, it is possible to form a foam having stable physical properties. Further, since the foam for a sealing material of the present invention is an aqueous emulsion, it does not cure in a mixing device in a short time, and it is not necessary to wash the device even when performing intermittent operation. Further, since it is used as an aqueous emulsion, it is not necessary to use an organic solvent even when washing the apparatus, and it is useful for maintaining a good working environment and keeping the health of the person engaged in the work.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing a manufacturing apparatus for a foam for a sealing material.

[Explanation of symbols]

 10 Mixing Chamber 12 Stirrer 14 Bottom 16 Nozzle 16a Tip of Nozzle 20 Tank 22 Tank 24 Tank 26 Pump 28 Pump 30 Pump 40 Workpiece (Headlight Main Body) 42 Seal Groove 44 Sealant Foam

Claims (3)

[Claims] 1. A foaming material for a sealing material is obtained by adding a foam stabilizer and a thickening agent to a one-part curable synthetic resin emulsion to mechanically foam the sealing material, and directly discharging it into a groove portion to be formed and drying. How to form. 2. The mechanical foaming of the sealing material is carried out by using a high-speed stirrer at a rotation speed of 500-2000 rpm.
The method for forming a foam for a sealing material according to claim 1, wherein the foaming is performed for 3 minutes. 3. Direct discharge to the groove portion to be formed is 50 to 50.
The method for forming a foam for a sealing material according to claim 1, which is performed at a discharge rate of 200 g / min.