KR101542513B1 - mixing runner of two-component coating materials for in-mold coating - Google Patents

Abstract

The present invention discloses a two-pack coating mixer runner for in-mold coating.
The two-component coating material mixing runner for the in-mold coating of the present invention is provided in a mold and has one end connected to the linear mixing head, and the turbulent kinetic energy generated in the linear mixing head is increased, polyol and isocynate are uniformly mixed with each other.

Description

[0001] The present invention relates to a two-component coating runner for in-mold coating,

The present invention relates to a mixing unit used in an in-mold coating process, and more particularly, to a runner for uniformly mixing a two-component coating material in an in-mold coating process.

Injection molded products of thermoplastic resins are used in a wide variety of fields such as automobiles, home appliances, and displays. However, in many molded products, a separate coating process is required in order to increase the durability, weather resistance, or the paint adhesion.

In this process, various problems arise such as environmental pollution caused by use of volatile solvent, unevenness of coating thickness, and manufacturing cost increase due to post-process. The in-mold coating is a new coating method in which a thermoplastic resin is injection molded, then a liquid curable coating material is injected into the mold, and a pressure of several MPa is maintained, thereby pressing the mold into a mold.

The material used in the in-mold coating is environmentally friendly because it does not contain volatile organic solvents and does not emit any organic compounds during the process, and because the injected coating adheres to the surface of both moldings, it is advantageous for thick coatings, It has the advantage to be obtained.

It is possible to reproduce a fine shape with excellent transferability of the surface of the mold. When a glass fiber reinforced resin is applied, a surface state similar to that of a resin-molded product without a fiber can be realized. In addition, a molding defect such as a weld line, a sink mark or the like can be prevented from appearing on the coating surface. In recent years, in-mold coating technology using polyurethane has been applied in advanced automotive fields in Europe in order to realize high gloss and scratch resistance on the surface of thermoplastic substrate. The polyurethane has a great advantage of being excellent in transparency, gloss, durability, resilience and mass production

Polyurethane is not very good in fluidity because it has a very high viscosity at low temperature and does not mix well. On the other hand, if the temperature is too high, hardening will result in difficult molding.

Therefore, it is necessary to maintain the temperature of each tank and the moving pipeline at a constant level in order to mix the mixture of the base and the hardener and to facilitate the discharge of the mixed raw materials. After the discharge into the mold is completed, The raw material should be completely removed.

1A and 1B, a general polyurethane production process is illustrated in which a liquid polyol is contained in one tank and a liquid polyol is contained in another tank. When the storage tank 10 and the feed pump connected to the isocynate storage tank are operated, the polyol stock solution and the isocynate stock solution are transferred to the mixing head through the respective supply pipes .

 The polyol and isocynate stock solution transferred to the mixing head collide with each other in the mixing head to generate turbulent flow and are mixed with each other by kinetic energy and injected into a mold having a predetermined shape, The surface of the substrate is coated in the mold.

Here, what is important in an in-mold coating process using a polyurethane is to homogeneously mix the subject of a polyurethane and a curing agent at a constant ratio. This is because the surface state of the coating varies depending on the degree of mixing, and chemical reactions and mechanical properties are greatly changed.

In this paper, a two-pack type mixing experiment apparatus was fabricated and a turbulent flow pattern with various Reynolds number and nozzle size was observed through a flow visualization experiment, and as the Reynolds number increased, And the characteristics are improved.

Here, the linear mixing head generally used has a simple structure, but has a problem that mixing of polyol and isocynate is not performed well.

1. Zuyev, K. S. and Castro, J. M., "Applications of chemo-rheology to develop process windows in reactive in-mold coating," Journal of Polymer Engineering, Vol. 22, No. 4, pp. 233-260, 2002. 2. Zuyev, K. S. and Castro, J. M., "Processing Studies in Reactive In-Mold Coatings for Thermoplastic Parts," SPE ANTEC'03, pp. 510-514, 2003. 3. Rios, M. C., "Multiple criteria optimization studies in reactive in-mold coating," Ph.D. Thesis, major, The Ohio State University, 2002. 4. Gite, V. V., Rajput, S. D., and Yemul, O. S., "Advances in polyurethane coating technologies," Chemical Weekly, Vol. 58, No. 2, pp. 201-208, 2012. 5. Gruber, M., " Integrated system for producing composites, " Krauss Maffei Technologies, U.S. Pat. 0317893, 2008. Gruber, M., " Method for Producing a Coated Composite Component, " KraussMaffei Technologies, U.S. Pat. 0243148, 2009. 7. Tucker, C. L. and Suh, N. P., " Mixing for reaction injection molding. I. Impingement mixing of liquids, " Polymer Engineering and Science, Vol. 20, No. 13, pp. 875-886, 1980.

It is an object of the present invention to provide a two-component coating material mixing runner for in-mold coating for uniformly mixing a two-component coating material in an in-mold coating process.

It is also an object of the present invention to provide a two-component coating material mixing runner for an in-mold coating which can be easily combined with a linear mixing head.

According to an aspect of the present invention, there is provided a runner for a two-pack type coating material, which is provided in a metal mold and has one end connected to the linear mixing head, (polyol) and the isocyanate (isocynate) are uniformly mixed.

Wherein the runner is connected to an outlet of the linear mixing head, the first flow line having a vertical cross section formed in a circular or semicircular shape according to a length section and having a horizontal cross section formed in an L shape; A second flow line formed in the same shape as the first flow line; And at least one third flow line connecting the first flow line and the second flow line.

The first flow line is formed to have a different vertical cross section according to a length section, thereby increasing the turbulent flow energy due to the collision between the polyol and the isocynate.

The in-mold coating process for solving the above-mentioned problems is characterized by being an in-mold coating process using a mixing head for a two-component coating material according to claim 1.

The two-liquid coating material injecting apparatus for solving the above-mentioned problems is characterized by being a two-liquid coating material injecting apparatus equipped with a mixing head for a two-liquid coating material according to claim 1.

The runner for the two-pack type coating material proposed in the present invention increases turbulent kinetic energy by the flow of polyol and isocynate inside,

This has the advantage that the polyol and isocynate can be uniformly mixed.

The two-component type coating material runner proposed in the present invention can mix the primary mixed mixture of polyol and isocynate in the mold again in the linear mixing head so that the polyol and isocynate can be uniformly mixed It has an advantage that it can be mixed.

1A is an exemplary view showing a two-part type polyurethane supply system.
FIG. 1B is an illustration showing an example of the linear mixing head shown in FIG. 1A.
Fig. 2 is an exemplary view showing the parameters of the linear mixing head shown in Fig. 1. Fig.
FIG. 3 is a diagram illustrating boundary conditions according to each section of the linear mixing head shown in FIG. 2. FIG.
FIG. 4 is a graph showing turbulent kinetic energy of a polyol injected into a linear mixing head, wherein (a) represents the turbulent kinetic energy of the polyol at the second interface shown in FIG. 3, and (b) Represents the turbulent kinetic energy of the polyol at the first interface shown in FIG.
FIG. 5 is an illustration showing the mixing ratio of polyol along the length direction of the linear mixing head.
6 shows a runner according to an embodiment of the present invention, wherein (a) shows a case where a vertical section is circular, and (b) shows a case where a vertical section is a semicircular shape.
7 is a cross-sectional view illustrating a comparison of the turbulent kinetic energy of each runner.
Figs. 8 and 9 are graphs showing turbulent kinetic energies at the cross section shown in Fig. 7 for the runners having a circular cross section and a semicircular cross section, respectively.
10 and 11 are graphs showing mixing ratios of polyols that appear as they pass through a runner having a circular cross section and a semicircular cross section.
12 shows an example of a runner made in various lengths.
Figs. 13 and 14 are illustrations showing mixing ratios of polyols appearing as they pass through the runner when the runner length is 12.5 mm and 16.5 mm, respectively.
Fig. 15 shows the mixing ratio of polyol to polyol and isocynate at very low flow rates of 0.7 g / sec and 1.3 g / sec, respectively.
Fig. 16 shows the results of analysis of the flow rate of the polyol and the isocynate flow rate of 3.5 g / sec and 6.5 g / sec, respectively.
17 is a graph showing the results of analysis of a case where the flow rates of polyol and isocynate are maintained at 4.35 g / sec and 5.65 g / sec, respectively, and a low viscosity material is applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of preferred embodiments of the present invention will be given with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Embodiments in accordance with the concepts of the present invention can make various changes and have various forms, so that specific embodiments are illustrated in the drawings and described in detail in this specification or application. It is to be understood, however, that it is not intended to limit the embodiments according to the concepts of the present invention to the particular forms of disclosure, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ",or" having ", or the like, specify that there is a stated feature, number, step, operation, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Hereinafter, a two-component coating material mixing runner for in-mold coating according to an embodiment of the present invention will be described in detail with reference to the drawings.

First, prior to describing the runner of the present invention, a mixing characteristic of a polyol and isocynate in a general linear mixing head is analyzed.

As a consideration for the analysis, the turbulent flow is assumed to be dominant, and the flow time is very short, less than 1 second, so that the curing does not occur.

Puriflow (polyol: 33900-1-0820, isocyanate: 38900-0-0820), a material manufactured by Votteler, Germany, was used, and the viscosity of polyol and isocynate was measured at 80 ° C The density was 1.12 g / ml and the density was 1.15 g / ml, respectively. The mixture ratio of polyol and isocynate was 100: 180.

ANSYS-CFX was used for the flow analysis and a k-ε turbulence model was applied. As shown in Fig. 3, the boundary conditions for the analysis were applied to the flow rate, pressure, and mixture ratio distribution.

Fig. 4 shows the analysis results for a polyol flow rate of 0.7 g / sec and an isocynate flow rate of 1.3 g / sec. The results are plotted in plane 2 defined in Fig. 3 and polyol turbulence Energy distribution. Where the color represents the turbulent energy distribution and the magnitude and direction of the vector represent the magnitude and direction of the velocity. It can be seen that large turbulent energy is generated at the cross section where the polyol and isocynate are in frontal collision, but it is extinguished at the discharge part.

FIG. 5 shows the mixing ratio of polyol in the cross section in the longitudinal direction. It can be seen that the two components are discharged from the mixing head in a state where they are hardly mixed. The Reynolds numbers of the polyol and isocynate are 25.9 and 25.3, respectively, in the above described analytical conditions, which is consistent with the results of Tucker and Suh 7 in which Reynolds numbers under 150 are hardly mixed.

Accordingly, it is an object of the present invention to provide a runner for a two-component coating material capable of uniformly mixing polyol and isocynate while increasing turbulent kinetic energy according to turbulent flow.

FIG. 6 is a view showing an example of a runner according to an embodiment of the present invention, wherein (a) shows a case where the vertical section of the runner is circular, and (b) is an example of a case where the vertical section of the runner is a half circle.

Referring to FIG. 6, the runners 100 and 200 are provided in a mold, and are connected to the linear mixing head, and increase the turbulent kinetic energy. The polyol, which is discharged from the linear mixing head 20, And functions to homogeneously mix the isocynate.

More specifically, the runners 100 and 200 include first flow lines 110 and 210, second flow lines 120 and 220, and third flow lines 130 and 230.

The first flow lines 110 and 210 are connected to the outlet of the linear mixing head, and the vertical cross section is formed in a circular or semicircular shape according to the length section, and the horizontal cross section is formed in an L shape.

The second flow lines 120 and 220 are formed in the same shape as the first flow lines 110 and 210.

At least one of the third flow lines 130 and 230 may be provided to connect the first flow lines 110 and 210 to the second flow lines 120 and 220.

Here, the linear mixing head 20 is formed in a cylindrical shape, and performs a function of primarily mixing polyol and isocynate introduced into the inlet formed on both sides of one end of the mixing head 20. In this case, .

7 is a cross-sectional view illustrating a comparison of the turbulent kinetic energy of each runner. Figs. 8 and 9 are graphs showing turbulent kinetic energies at the cross section shown in Fig. 7 for the runners having a circular cross section and a semicircular cross section, respectively. 10 and 11 are graphs showing mixing ratios of polyols that appear as they pass through a runner having a circular cross section and a semicircular cross section. 12 shows an example of a runner made in various lengths. Figs. 13 and 14 are illustrations showing mixing ratios of polyols appearing as they pass through the runner when the runner length is 12.5 mm and 16.5 mm, respectively. Fig. 15 shows the mixing ratio of polyol to polyol and isocynate at very low flow rates of 0.7 g / sec and 1.3 g / sec, respectively. Fig. 16 shows the results of analysis of the flow rate of the polyol and the isocynate flow rate of 3.5 g / sec and 6.5 g / sec, respectively. 17 is a graph showing the results of analysis of a case where the flow rates of polyol and isocynate are maintained at 4.35 g / sec and 5.65 g / sec, respectively, and a low viscosity material is applied.

Hereinafter, with reference to the drawings, an experimental example in which mixing characteristics of a polyol and isocynate introduced into the runners 100 and 200 according to the present invention are analyzed according to the cross-sectional shape, length, flow rate and viscosity of a runner The mixing characteristics of polyol and isocynate are explained in this paper.

[First Experimental Example]

The first experimental example is an example for analyzing the mixing characteristics of polyol and isocynate according to the cross-sectional shape of the runner.

First, flow analysis was carried out for each of the circular and semicircular cross-sectional shapes of the runner, wherein the flow rates of polyol and isocynate were set at 7 g / sec and 13 g / sec, respectively.

(A), section (b), section (c), and section (d) in cross sections for comparing the turbulent kinetic energy for each of the runner positions shown in FIG. 7 are shown in FIGS. 8 and 9, The turbulence energy generated by the flow becomes larger in the case of the semicircular cross section than in the case of the cross section.

On the other hand, it can be seen that as the runner approaches the exit, the size of the turbulent flow is decreasing, and the turbulent kinetic energy value is very small irrespective of the shape of the runner section.

[Second Experimental Example]

The second experimental example is an experiment for analyzing mixing characteristics of polyol and isocynate according to runner length.

10 and 11, the left side of each of FIGS. 10 and 11 is the mixture ratio distribution according to the runner length, and the right result shows the mixture ratio distribution at the runner exit side.

That is, when the runner has a circular cross-section, only the isocyanate is present in the right portion, and mixing is hardly observed. On the other hand, when the runner has a semicircular cross-section, isocynate is not present in the center of the cross-section, but it can be seen that mixing with the polyol is better than the circular cross-section.

More specifically, in the second experimental example, a semicircular cross-sectional runner which is advantageous for mixing polyol and isocynate was used, and the flow rates of polyol and isocynate were 7 g / sec and 13 g / sec In order to understand the mixing characteristics according to the variation of the runner length, the flow analysis according to the runner shape was performed for the lengths of 8.5 mm, 12.5 mm and 16.5 mm, respectively, as shown in FIG.

FIGS. 13 and 14 show mixing ratios of polyols appearing as they pass through the runner when the runner length is 12.5 mm and 16.5 mm, respectively.

Referring to FIGS. 11 to 14, as the runner length increases to 12.5 mm and 16.5 mm as compared to the runner length of 8.5 mm, the turbulent flow becomes more active, so that the mixture of polyol and isocynate is very It can be confirmed that it is uniformly performed.

Particularly, it can be seen that the runner length of 16.5 mm is suitable for satisfying uniform mixing of polyol and isocynate. However, when the runner length was 12.5 mm and 15.5 mm, the required inlet pressure was very high at 109 bar and 164 bar, respectively.

[Third Experimental Example]

The third experimental example is to analyze the mixing characteristics of the polyol and isocynate with varying flow rate while the runner length is fixed at 16.5 mm so as to satisfy the uniform mixing of the polyol and isocynate. One experiment.

According to the results of the third experimental example, the mixing ratio of the polyol to the case where the flow rates of the polyol and the isocynate are very slow, such as 0.7 g / sec and 1.3 g / sec, respectively, 16, the flow rate of the polyol was set to 3.5 g / sec, and the flow rate of the isocyanate was set to 6.5 g / sec. The mixing ratio of the polyol was analyzed.

According to the third experimental example, when the flow rate of the polyol and the isocynate is 7 g / sec and 13 g / sec, respectively, as shown in FIG. 14, the turbulent kinetic energy increases as the flow rate increases It can be seen that mixing is performed more uniformly.

When the flow rates of polyol and isocynate were 3.5 g / sec and 6.5 g / sec respectively, the injection pressure was 55 bar and the maximum pressure of the liquid polyurethane injection system was 100 bar.

However, it can be seen that the mixing is not sufficiently uniform as compared with Fig. 14 which is a result when the flow rates of polyol and isocynate are 7 g / sec and 13 g / sec, respectively.

[Fourth Experimental Example]

As shown in the results of the third experimental example, the fourth experimental example can improve the mixing characteristics by further increasing the flow rate of the polyol and isocynate. However, since the injection pressure required is increased and bubbles are generated in the mold Based on the problem, it is an experiment to analyze the mixing characteristics when using a low viscosity material without rapidly increasing the flow rate.

The viscosity of polyol and isocynate was 170 cps at 75 ° C and 75 cps at 80 ° C, respectively. The viscosity of polyol and isocynate was 80 cP , The density was 1.118 g / ml and 1.17 g / ml, respectively, and the mixing ratio of polyol and isocynate was 100: 130.

Fig. 17 shows the results of analysis of the case where the flow rates of the polyol and isocynate are maintained at 4.35 g / sec and 5.65 g / sec respectively and a low viscosity material is applied. It can be seen that mixing is very uniform compared to FIG. 16 which is the result of applying the same flow rate since the viscosity of the isocyanate isocyanate is reduced from 320 cps to 75.

The injection pressure required was 42 bar and it was judged that there was no problem in the in-mold coating molding.

Therefore, the two-component coating material mixing runner for the in-mold coating proposed in the present invention has an advantage that the polyol and isocynate supplied from the outside through the mixing head can be injected and uniformly mixed.

The above-described advantages are derived from the first to fourth experimental examples. More specifically, the two-component coating material mixing runner for the in-mold coating is formed into a semicircular shape, , And it was found that as the length of the runner increases, and as the flow rate of the coating increases, the mixing becomes more uniform.

Additionally, it was necessary to limit the flow rate of the coating to reduce coating injection pressure and bubble generation, wherein a low viscosity coating could be used to further reduce the injection pressure and further improve the mixing properties of the polyol and isocynate have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications, and variations will readily occur to those skilled in the art without departing from the spirit and scope of the invention. Therefore, it should be understood that the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense, and that the true scope of the invention is indicated by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof, .

100, 200: Runner
110, 210: a first flow line
120, 220: a second flow line
130, and 230: a third flow line

Claims (5)

Two-component coating mixer runner for in-mold coating:
A first flow line, a second flow line, and at least one third flow line connecting the first flow line and the second flow line;
Wherein the first flow line is connected to an outlet and an inlet of the linear mixing head and is formed in an L-shaped horizontal section, the vertical section of the inlet is circular, and the vertical section of the outlet connected to the third flow line is semicircular,
Wherein the second flow line has the same shape as the first flow line and has a shape inverted from the first flow line to the inlet and the outlet,
Wherein the third flow line has one side connected to the outlet of the first flow line and the other side connected to the inlet of the second flow line.
A two-part coating material mixing runner for in-mold coating comprising one or more flow lines of first, second, and third flow lines of a two-component coating material mixing runner for in-mold coating according to claim 1.
delete An in-mold coating process using a two-component coating material mixing runner for in-mold coating according to claim 1 or 2.
A two-part coating material injection device equipped with a two-component coating material mixing runner for in-mold coating according to any one of claims 1 to 3.

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