KR19980017940A - Polyurethane Microcell Foaming Mix with Ultrasonic Oscillating Horn - Google Patents

Abstract

The present invention relates to an ultrasonic mixhead for microcellular foaming of a polyurethane for allowing the size of bubbles to be finely foamed when foaming into a polyurethane by impingement mixing of polyol and isocyanate at high pressure. In the present invention, when the polyol mixture and the isocyanate mixture are mixed to be injected into a mold and injected into the mold along the outlet, the bubble nucleus is attached when the mixture is foamed by the ultrasonic wave by attaching an ultrasonic oscillator that generates an ultrasonic wave on the outlet. An object of the present invention is to provide a polyurethane foaming mix head having an ultrasonic oscillation horn for finely forming the same. The present invention is provided with the slewing hole 33 formed in the same axial direction as the mixture outlet of the mix head 10, and slidably coupled to the cylinder 31, at an end penetrating perpendicularly to the outlet 19. A slider (30) having a slide hole (35) communicating with the smut hole (33); Moving means for reciprocating the slider 30; The cross section is fixed on the outlet 19 so as to be located on the axis of the slider 30, it is composed of a horn 40 connected to the ultrasonic generator is slidably coupled to the slide hole (35).

Description

Polyurethane Microcell Foaming Mix with Ultrasonic Oscillating Horn

The present invention relates to an ultrasonic oscillating mixhead for miniaturizing the cell structure of polyurethane foam, and more specifically, polyol and isocyanate are reacted with a foaming agent to foam into polyurethane foam. The present invention relates to a polyurethane microcell foaming mixhead with an ultrasonic oscillating horn for allowing the cell structure of polyurethane foam to be foamed more finely.

In general, it is well known that polyurethane is widely used to improve the insulation, heat insulation, sound insulation and dustproofing effect. Polyurethane foam occupies a part of the volume of the base material by decomposing the blowing agent mixed in the polyurethane resin to generate gas by phase change to form a bubble having a distinct boundary with the surrounding resin. In the case of foam materials, mechanical properties are generally lower than those of resins, but the weight reduction due to low density, material saving, improvement of shock absorption and specific strength, improvement of sound insulation and heat insulation, and volumetric shrinkage due to density change during curing of the base material Compensation has the advantage of stabilizing the dimensions of the product.

In addition, as described above, polyurethane foam has excellent heat transfer blocking effect, and is light and excellent in water resistance, and thus has been widely applied to insulation materials for cold appliances such as refrigerators, soundproof walls of automobiles, and bumpers for automobiles having high impact strength. .

Polyurethane foam having this feature uses a blowing agent to form a polyurethane foam structure. The blowing agent is classified into a physical blowing agent and a chemical blowing agent and shows various physical properties depending on the blowing agent.

As the physical blowing agent, CFC-11, CFC-12, CFC-14b and the like are used, and as the chemical blowing agent, water, azodicarbonate, active azodicarbonate, 5-phenyltetrazole, sodium bicarbonate and the like are used.

Generally, polyurethanes are produced through the reaction of R-NCO (isocyanate) + R'-OH (polyol, polyol)-→ R-NH-CO-R '(polyurethane, Polyurethane). At the same time, a foam structure having numerous bubbles is formed by vaporization of the blowing agents.

When the size of the bubbles constituting the foam increases, the thermal insulation performance, non-impact strength, etc. are reduced. Therefore, it is important to form fine bubbles of uniform size inside the foam.

However, the size of the foam in the polyurethane foam is not only different depending on the mixing ratio and type of blowing agent, but also in the case of the foam produced by the general foaming process, it forms a coarse and huge bubble hole. Such bubble holes cause a decrease in strength and a decrease in heat insulating performance. In general, it is known that the insulation performance increases as the average diameter of the bubbles decreases.

In addition, in case of products such as refrigerators and bumpers of automobiles, when foamed with a general polyurethane foam, coarse bubbles are formed and insufficient filling is made in a narrow cavity of the mold, and the inside of the mold is hollowed out, resulting in uneven heat transfer coefficient. The problem may easily occur due to external impact.

Polyurethane foam as described above is in the mold by the mix head of the reaction injection molding (Reaction Injection Molding) having a mixing chamber in which the mixture, that is, the polyol mixture and the isocyanate mixture is introduced and mixed as shown in Figure 1a and 1b It is injected into and foamed.

The above-described mix head 10 is provided with a hydraulic inlet 13a and a hydraulic outlet 13b which simultaneously perform a function of supplying or discharging hydraulic pressure to the cylinder 11 on one side. The cylinder 11 is provided with a diaphragm 17a integrally formed with the piston 17. When fluid is injected into the hydraulic inlet 13a, the piston 17 reciprocates together by the diaphragm 17a. That is, when the fluid flows into the hydraulic outlet 13b, the piston 17 is raised to expose the mixture inlets 15a and 15b on the outlet 19 so that the polyol is discharged to the outlet 19 as shown in FIG. The mixture and the isocyanate mixture come in. In addition, when the fluid is introduced into the hydraulic inlet 13a and the piston 17 is lowered, as shown in FIG. 1A, the mixture inlets 15a and 15b are formed in the bypass grooves 18a and 18b formed on the circumferential surface of the piston 17. The polyol mixture and the isocyanate mixture do not enter the outlet port 19 but are circulated along the mixture circulation holes 16a and 16b.

Therefore, when the polyol mixture and the isocyanate mixture are introduced into the respective mixture inlets 15a and 15b and enter the outlet 19, the two fluids in turbulent flow collide with each other to achieve a complete mixing, which is directly at their own pressure. As a result, it is pushed out of the outlet 19 and flows into the mold or the refrigerator and is foamed.

Therefore, the outlet 19 performs the mixing function of mixing with the guide function for discharging the polyol mixture and the isocyanate mixture to the outside.

As can be seen from the above, the conventional mixhead has no special features other than the function of merely mixing the polyol mixture and the isocyanate mixture and injecting the mold. In other words, the foaming process of the admixture is mainly foamed by a chemical reaction, so that the growth of nuclei and the size of bubbles are uniformly coarse, so that it is difficult to expect an improvement in thermal insulation and impact strength.

The present invention has been invented to solve the problem as described above.

An object of the present invention is to attach an ultrasonic oscillator for generating an ultrasonic wave on the discharge port when the polyol and isocyanate are mixed and injected into the mold along the discharge port, so that a plurality of bubble nuclei are generated by the ultrasonic wave, and eventually finer bubbles It is to provide a mix head for foaming polyurethane micro-cells.

Polyurethane microcellular foamed mixing head with ultrasonic oscillating horn according to the present invention is provided with a bypass groove on the circumferential surface, and is slidably coupled in a cylinder to reciprocate as hydraulic pressure is supplied or discharged, and a polyol mixture A mixture head for filling urethane having a mixture inlet through which the isocyanate mixture is introduced and a mixture circulation hole returned therein, and an outlet through which the piston is slidably coupled;

A slider having an circumferential hole formed in the same axial direction as the outlet, slidably coupled to the cylinder, and having a slide hole communicating with the circumferential hole at an end penetrating in a direction perpendicular to the outlet;

Moving means for reciprocating the slider;

It can be achieved with a horn connected to the ultrasonic generator which is fixed on the outlet so that the cross section is located on the axis of the slider and is slidably coupled to the slide hole.

Figure 1a is a sectional view of the main portion showing an example of a conventional polyurethane foam mixing head, the state before the operation of the piston.

FIG. 1B is a cross-sectional view of a main portion showing an example of a conventional polyurethane foam mixing head, and is a state after operation of the piston. FIG.

Fig. 2 is a sectional view showing the main parts showing the mix head for foaming polyurethane microcells with the ultrasonic oscillation horn of the present invention, which is before the piston is operated.

Fig. 3 is a sectional view showing the main parts of a mix head for foaming polyurethane microcells with an ultrasonic oscillation horn according to the present invention, in which a piston is operated and an ultrasonic wave is applied at the same time.

4 is a cross-sectional view taken along the line a-a of FIG. 2.

*** Explanation of symbols for main parts of drawing ***

10: Mixhead 11: Cylinder

13a: hydraulic inlet port 13b: hydraulic outlet port

15a, 15b: mixture inlet 16a, 16b: mixture circulation hole

18a, 18b: Bypass Home 19: Outlet

19a: passage 30: slider

It is cylinder 33

35: slide ball 37: O-ring

40: Horn 41a, 41b: Hydraulic supply tube

Hereinafter, with reference to the accompanying drawings, the components for the ultrasonic micro oscillation horn attached polyurethane micro-cell foam according to the object of the present invention will be described in detail.

Referring to FIG. 3, FIG. 3 shows a state in which the microcellular foamed ultrasonic horn of the polyurethane according to the present invention is coupled to an EMB type mixhead.

The present invention can be largely divided into a mix head 10, a slider 30, a conveying means, an ultrasonic wave generator and a horn 40.

The mix head 10 includes mixture inlets 15a and 15b through which a polyol mixture and an isocyanate mixture are introduced, and also includes a mixing chamber which is introduced into the mixture inlets 15a and 15b and an outlet 19 through which the mixture is discharged. I have it.

The above-described mix head 10 is provided with hydraulic inlets 13a and 13b and hydraulic outlets 13b which simultaneously perform a function of supplying or discharging hydraulic pressure to the cylinder 11 on one side. The cylinder 11 is provided with a diaphragm 17a integrally formed with the piston 17. When fluid is injected into the hydraulic inlet 13a, the piston 17 reciprocates together by the diaphragm 17a. The outlet 19 is connected to the mixture inlets 15a and 15b through which the polyol mixture and the isocyanate mixture are introduced at a predetermined ratio.

The slider 30 is coupled to the cylinder 31 so as to slide through at right angles on the passage 19a of the outlet 19 described above. The slider 30 also has an oil hole 33 formed in the same axial direction as the outlet, and includes a slide hole 35 in the cross section of the axis. The scavenging hole 33 functions to switch the passage 19a of the outlet 19 from a straight line to a curved line.

The conveying means is a power supply device for reciprocating the slider 30 described above, and the respective tubes 41a and 41b through which hydraulic pressure is introduced or discharged are provided at one side of the slider 30. Therefore, when the hydraulic pressure flows into the tube 41b, the partition wall 30a is pushed forward by the pressure, and the fluid contained in the hydraulic cylinder 31 is discharged into the other tube 41a. Such an operation is repeatedly performed in each of the tubes 41a and 41b, thereby causing the slider 30 to reciprocate.

The ultrasonic generator is an assembly having a vibrator operated by a generally known power source although not shown in the drawings.

Horn 40 is vibrated in connection with the above-described ultrasonic generator, the cross section is located on the passage (19a) of the discharge port 19, the end of which is slidable in the slide hole 35 of the slider 30 Is located. Reference numeral 37 is an O-ring.

When described in detail the working example and the working effect on the polyurethane microcellular foamed mixing head having an ultrasonic oscillator according to the present invention configured as described above.

When the ultrasonic wave generator is operated, ultrasonic waves are oscillated in the horn 40. At this time, as shown in FIG. 3, when the hydraulic pressure flows into the cylinder 31, the slider 30 is advanced. When the slider moves forward, the slide hole 35 slides along the circumference of the horn 40 so that the end of the horn 40 is placed into the slewing hole 33. In this case, as shown in FIG. 4, the diameter of the outlet passage 19a gradually decreases as the diameter of the passage hole 19a and the center of the discharge hole 19 are shifted from each other.

Therefore, the mixture of the mixture is more evenly made at the point where the passage of the discharge port 19 becomes narrow, that is, the point where the mixture that enters the throttle hole 33 passes through the narrow passage, is introduced into the throttle hole 33. .

Since the mixture introduced into the scavenging hole 33 passes through the end of the horn 40, that is, around the horn, a plurality of bubble nuclei are formed by the ultrasonic oscillation of the horn before the mixture is discharged to the outside, and the amount of the blowing agent is constant. The size of becomes small.

As described above, the polyurethane microcellular foamed mixing head having an ultrasonic oscillator according to the present invention is characterized in that the mixture becomes fine in the process of passing through the outlet when the polyol mixture and the isocyanate mixture are mixed in the mix head and filled into the mold. By vibrating, the foaming core becomes fine during foaming, and the bubbles formed on the interface are also minutely formed to improve the thermal insulation performance and impact strength. In addition, the mixture having micronized bubbles can form microcellular foam casting in the narrow cavity of the mold to prevent the cavity cavitation phenomenon.

Polyurethane microcellular foamed mixing head having an ultrasonic oscillator according to the present invention described above for illustrative purposes only and those skilled in the art to practice various modifications and applications based on the present specification It will be appreciated that such modifications and applications are intended to be included in the true spirit and scope of the present invention, and the appended claims.

Claims (2)

A slider having an circumferential hole formed in the same axial direction as the mixture outlet of the mixhead and slidably coupled to the cylinder, the slider having a slide hole communicating with the blast hole at an end penetrating in a direction perpendicular to the outlet; Moving means for reciprocating the slider; The ultrasonic oscillating horn is attached to the polyurethane micro-cell foamed mixing head, characterized in that the cross section is fixed to the outlet so as to be located on the axis of the slider, consisting of a horn connected to the slidably coupled ultrasonic generator. The ultrasonic oscillating horn according to claim 1, wherein the moving unit is slidably coupled to a partition wall coupled to the slider on one side of the cylinder, and a tube into which hydraulic pressure is introduced or discharged from the left and right sides of the partition wall. This attached polyurethane mix head for microcellular foaming.