JPH09304264A - Confirmation of wettability to solid wall surface of molten resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and accurately measure the wet angle of a resin to the surface of a solid by bringing the resin pellet placed on the smooth surface of an object to be inspected to a molten state and taking the image thereof. SOLUTION: The laser beam of a light emitting apparatus is guided into a heating furnace 30 filled with nitrogen gas and regulated to a predetermined temp. through a beam diffuser 20 to irradiate the liquid droplet 34 of the molten resin placed on the metal plate 32 having a smooth horizontal surface being the object to be inspected in the furnace and the image thereof is formed on a screen 50 through a zoom-up lens 40. The obtained image is taken by a CCD camera 60 and recorded by a VTR deck 70 to be projected on a monitor television 80. At a point of time when the shape change of the liquid droplet is stopped, the wet angle of the molten resin on the surface of a metal solid is observed. That is, a wet angle is calculated from the angle of inclination of an equilateral triangle of the max. diameter of a bottom surface and height from the shape of the liquid droplet 34. By this constitution, the wet angle can be simply and accurately measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for confirming wettability of a molten resin on a solid wall surface.

[0002]

2. Description of the Related Art Conventionally, as a method of confirming wettability, a method of dripping water droplets on a solid surface such as metal or plastic to measure a wetting angle or injecting another molten resin into a molten resin with a nozzle There is known a method of confirming the wettability between molten resins by measuring the contact angle at that time, that is, the wetting angle.

[0003]

However, the method for confirming the wettability of the molten resin to the solid wall surface, which is strongly related to the solid wall slip of the molten resin, which is considered to be greatly involved in the color changeability and the resin changeability. But it was not established until now. In the present invention, a method of confirming the wettability of these molten resins to the solid wall surface is established, and based on the physical properties obtained by this confirming method, a good blow-molded product of color change or resin change can be continuously and stably produced. Intended to produce.

[0004]

In order to solve the above problems, in the present invention, a method for confirming the wettability of a molten resin to a solid wall surface is performed in an atmosphere of an inert gas such as nitrogen gas. In a furnace heated to a temperature and controlled in temperature, a solid having a smooth flat surface, which is an object to be inspected, is allowed to stand so that the flat surface is horizontal, and a resin pellet piece is placed on the surface of the solid and melted. Then, an image of the molten resin in a droplet state was photographed and the wetting angle of the molten resin with respect to the solid surface was measured. Further, in the second invention, the method for measuring the wetting angle of the molten resin with respect to the solid surface in the first invention is converted from the ratio of the height of the droplet of the resin placed on the horizontal solid surface to the maximum diameter of the bottom. The angle of inclination obtained was used to determine the wettability of the molten resin to the solid wall surface.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a method for confirming the wettability of a molten resin to a solid wall surface is provided in a furnace which is heated to a predetermined temperature in an inert gas atmosphere such as nitrogen gas and whose temperature is controlled. A molten resin that is in a droplet state by placing a solid having a smooth flat surface, which is an object, so that the flat surface is horizontal, and placing resin pellet pieces on the surface of the solid Is taken to measure the wetting angle of the molten resin with respect to the solid surface, and the wetting angle of the molten resin with respect to the solid surface can be accurately measured by a relatively simple method. Also, the method of measuring the wetting angle of the molten resin with respect to the solid surface should be determined by the tilt angle obtained by converting from the ratio of the height of the droplet of the resin placed on the horizontal solid surface and the maximum diameter of the bottom side. Since the wettability can be visually and quantitatively grasped, the reliability is high.

[0006]

Embodiments of the present invention will be described in detail below with reference to the drawings and experimental data. 1 to 5 and Table 1 to
Table 3 relates to the examples of the present invention, FIG. 1 is an overall configuration diagram of the wetting angle measuring device, FIG. 2 is a graph showing the measurement results of the wetting angle, and FIG. 3 is the adhesion work estimated from the results of FIG. FIG. 4 is a graph showing the correlation between the wetting angle and the slip speed, and FIG. 5 is a graph showing the correlation between the work of adhesion and the slip speed. Table 1 shows the surface condition of the solid surface, and Table 2
Indicates the data of the type of resin material and the temperature in the specified furnace, and Table 3
Shows the data of wetting angle, work of adhesion and slip speed.

[0007]

[Table 1]

[0008]

[Table 2]

[0009]

[Table 3]

The wetting angle measuring device 100 is constructed as shown in FIG. 1, and the laser light emitted from the He-Ne laser light emitting device 10 is passed through the light diffuser 20 and then filled with nitrogen gas. It is introduced into the heating furnace 30 whose temperature is adjusted to a predetermined temperature by the temperature adjusting device 90, and the droplet 34 of the molten resin placed on the metal plate 32 having a smooth horizontal plane, which is the subject in the furnace, is irradiated with the droplet 34. Further, an image is formed on the screen 50 via the zoom-up lens 40. The image obtained in this way is photographed by the CCD camera 60, recorded by the VTR deck 70, and when the shape change of the droplet is stopped by being displayed on the monitor TV 80, the wetting angle of the molten resin on the surface of the metal solid is measured. Observe. That is, the height of the droplet 34 and the maximum diameter of the bottom surface were read from the shape of the droplet 34 placed on the smooth solid surface 32, and the wetting angle was obtained from the inclination angle of the isosceles triangle composed of the maximum diameter and the height. During observation, to prevent the molten resin from oxidizing and affecting the wetting angle,
The heating furnace 30 was filled with nitrogen gas.

When the resin pellet pieces are heated to a predetermined temperature in the heating furnace 30, they are melted into a droplet state.
The wetting angle of the molten resin on the surface of the metal solid was measured by photographing the state of the droplet from the side. As the light source, He-Ne laser light was used. The metal solid test plate 32 is a metal plate made of carbon steel having a size of 10 mm in length, 10 mm in width, and 3 mm in thickness. The test surface is a carbon steel plate (surface roughness (maximum height) as shown in Table 1. ) 0.4μ
m), carbon steel plate (surface roughness (maximum height) 1.6 μm),
A fluororesin-coated (PTFE-coated) carbon steel plate and a chrome-plated carbon steel plate, both of which are coated on the surface of a carbon steel plate having a surface roughness (maximum height) of 0.4 μm. on the other hand,
The resin pellets placed on this test plate 32 are
As shown in Table 2, three types of high-density polyethylene HDPE, polypropylene PP, and polycarbonate PC were used. These resin pellets were cut into a prism shape of 2.5 to 2.7 mg, and placed so that the longitudinal direction of the resin pellet was vertical to the plate.

The image data obtained by the experiment is taken into the image processing apparatus and is displayed as a still image on the monitor screen.
The wetting angle was determined using a program that measures the angle in a still image attached to the image processing device.

FIG. 2 shows the results of the wetting angle (contact angle) for the four types of resin PP and resin PC in Table 2 for the four types of solid surfaces a, b, c, and d in Table 1 (for resin HDPE). Is a long relaxation time and was not measured this time). Further, FIG. 3 shows the work of adhesion calculated from the above.
The work of adhesion W _A simply represents the energy change in the adhesion wetting when the liquid adheres to the solid surface as droplets, and is given by the following equation. W _A = γsv + γLv−γsL (1) Here, γsv, γLv, and γsL represent energy on the solid surface, the liquid surface, and the solid-liquid interface, respectively.

The interfaces of liquid, solid and gas are balanced by the following relational expression derived by Young. γsv-γsL = γLv (1 + cosθ) ········ (2) Thus, (1) and _{(2), W A = γLv (1 +} cosθ) ············ (3) Energy γLv on the liquid surface was calculated by a method of estimating the surface tension of the polymer at the melting temperature from the relationship between the surface tension and the specific volume at room temperature and the specific volume at any temperature. The value used is 18.8 mJ / for PP (230 ° C)
m ² and PC (260 ° C.) are 29.0 mJ / m ² .

According to FIG. 2, in the experiment using PP as the resin, the wetting angle was smaller than that of PC as a whole. Regarding the influence of the material and surface roughness of the solid surface, the case of fluororesin coating and carbon steel (surface roughness (maximum height) 0.
In the case of 4 μm), the wetting angle was small. According to the result of the work of adhesion in FIG. 3, when the solid interface is changed in the same molten resin, the work of adhesion becomes smaller as the wetting angle becomes larger. On the other hand, in the case of different molten resins, in the case of PC, although the wetting angle shows a larger overall value than that of PP, the surface energy of the molten resin is much larger than that of PP. Indicates a large value.
As can be seen from the equation (3), the work of adhesion W _A is a function of the wetting angle θ and the surface energy γLv of the molten resin, and it can be seen that the influence of the surface energy of the molten resin has a great influence.

Next, FIG. 4 shows the correlation between the measurement result of the slip velocity on the wall surface and the wetting angle. As can be seen from this, regarding the resin types, PP, PC,
The slip speed increased in the order of HDPE. Regarding the type and surface condition of the solid interface, the slip speed is large when using a fluororesin-coated wall surface or carbon steel (surface roughness (maximum height) 0.4 μm), and when using a chromium-plated wall surface or carbon steel (surface roughness (maximum height) It was found that the slip speed was low when 1.6 μm).

Based on the above results, wetting angle, work of adhesion,
Table 3 shows the arithmetic mean value and the slip speed at that time for each test. FIG. 4 shows the relationship between the wetting angle and the slip speed under the test conditions shown in Table 3. According to this, the correlation coefficient of PP and PC as a whole is as low as 0.29, and there is almost no correlation, but when it comes to PP alone, the correlation coefficient is 0.77, and for PC it is 0.9.
Therefore, when the resin type is fixed, there is a high correlation. Similarly, FIG. 5 shows the relationship between the work of adhesion and the slip speed under the test conditions shown in Table 3. At this time, the correlation coefficient between PP and PC as a whole is high at 0.94, and it is considered that the work of adhesion and the slip speed have a high correlation.
It is considered that this is because the work of adhesion, which is more affected by the molten resin than the wetting angle, has a higher correlation with the slip speed.

From the above, regarding the molten resin, P
PP, which has a smaller work of adhesion than C, has a higher slip speed, and the solid interface has a fluororesin coating that has a smaller work of adhesion than chromium plating or carbon steel (surface roughness (maximum height) 1.6 μm). Carbon steel (surface roughness (maximum height) 0.4 μm) tends to have a higher slip speed, and it is considered that there is a high correlation between the wettability with respect to the wall surface and the slip speed, which was considered using the work of adhesion as an index. .

As described above, in the present invention, a solid having a smooth flat surface, which is an object to be inspected, is placed in a furnace heated to a predetermined temperature in an inert gas atmosphere such as nitrogen gas and adjusted in temperature. The resin pellet piece is placed on the surface of the solid in a molten state by standing still horizontally, and an image of the molten resin in a liquid droplet state is photographed to obtain the wetting angle of the molten resin with respect to the surface of the solid. As a result of the experiment, the following findings were obtained. It has become possible to accurately measure the wetting angle between the solid interface and the molten resin for each molten resin and solid interface. As a result of comparing the work of adhesion calculated from the wetting angle and the measurement result of the slip speed, it was found that the slip speed tends to increase as the work of adhesion becomes smaller. It was confirmed that there is a high correlation between the property and the slip speed. As a result of measuring the wetting angle between the solid interface and the molten resin,
In the experiment in which the resin is PP, the wetting angle is smaller than that of PC as a whole. In addition, the influence of the material and surface roughness of the inner surface of the pipeline is large in the case of fluororesin coating and carbon steel (surface roughness (maximum height) 0.4 μm), the wetting angle is large, and chromium plating and carbon steel (surface Roughness (maximum height) 1.6 μm)
In this case, the wetting angle becomes smaller, and as a result, the wall material slip becomes larger when the pipeline material is coated with fluorine rather than chrome, and when the surface roughness is 0.4 μm or less, the wall slip becomes larger, and color change or It was found that the resin change was improved.

[0020]

As described above, in the present invention, the wetting angle of the resin with respect to the solid surface can be simply and
In addition to being able to measure accurately, the work of adhesion and the slip speed can be estimated from this value, so that a molded product with good color change and resin change can be obtained.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a wetting angle measuring device according to the present invention.

FIG. 2 is a graph showing a measurement result of a wetting angle according to the present invention.

FIG. 3 is a graph showing work of adhesion according to the present invention.

FIG. 4 is a graph showing a correlation between a wetting angle and a slip speed according to the present invention.

FIG. 5 is a graph showing the correlation between work of adhesion and slip speed according to the present invention.

[Explanation of Codes] 10 Light Emitting Device 20 Light Diffuser 30 Heating Furnace 32 Metal Plate 34 Resin Droplet 40 Zoom-up Lens 50 Screen 60 CCD Camera 70 VTR Deck 80 Monitor TV 90 Temperature Control Device 100 Wetting Angle Measuring Device

Claims (2)

[Claims] 1. A method for confirming the wettability of a molten resin to a solid wall surface, the method comprising the steps of: A solid having a flat surface is allowed to stand so that the flat surface is horizontal, and a resin pellet piece is placed on the surface of the solid to be in a molten state, and an image of the molten resin in a droplet state is photographed. A method for confirming the wettability of a molten resin to a solid wall by measuring the wetting angle of the molten resin with respect to the solid surface. 2. The method for measuring the wetting angle of the molten resin with respect to the solid surface is obtained by converting from the ratio of the height of the liquid droplets of the resin placed on the horizontal solid surface to the maximum diameter of the bottom side, and using the obtained inclination angle. The method for confirming the determined wettability of the molten resin to a solid wall surface according to claim 1.