JPS60217244A - Adhesion control of coating films in coating process including plasma pretreatment - Google Patents

Abstract

PURPOSE:When the article to be coated is previously treated with plasma, the emission speactra is detected and monitored to control the adhesion strength of the coating film depending on plasma quantity to ensure easily and steadily the prevention in decrease or fluctuation in adhesion strength. CONSTITUTION:In the coating operation which is accompanied by pretreatment with microwave plasma, the intensity or energy of the emission spectra of the plasma for pretreatment is monitered so that the fluctuation in intensity or energy tells the change in adhesion strength of the coating films. Microwaves are generated in the plasma treatment system provided with microwave generator 1, isolator 2, power monitor 3, matching device 4, gas bomb 6 and gas flow meter 7 and fed through duct 5, then combined with a gas from pipe 8 to generate plasma in the chamber 10. The plasma generated sent through quartz tube 11, joint 12 into the evacuated reactor 13 to irradiate the substrate with the plasma from pipe 15. At this time, the plasma emission is sent through optical fiber 17 to the spectrophotometer 18.

Description

DETAILED DESCRIPTION OF THE INVENTION In order to improve the adhesion of coating films, especially to olefin and C-based resins, the present invention uses plasma i! The present invention relates to a method and apparatus for managing variations in adhesion strength of coatings formed by coating with one treatment.

Conventionally, in microwave plasma processing equipment used in this type of equipment, parameters for generating plasma are set in advance and a predetermined amount of plasma is pretreated. This was confirmed later based on adhesion (peel) strength. For example, in the microwave plasma processing apparatus shown in FIG. 1 (described later), the output and oscillation time of the microwave generator 3, the type and flow of processing gas in the gas cylinder 6, and the degree of vacuum in the processing chamber 13 are □
Parameters and meters that define the amount of plasma generated can be monitored using the power monitor 3, gas flow meter 7, and vacuum gauge (not shown), but they are not only complicated (but also can be used to monitor fluctuations in the amount of plasma generated). It was difficult to detect accurately during processing.

) Yo. A, you'M t* "El 5ff LC!
＜ f: M If: += 64F, the coating film can be easily and reliably prevented from changing, such as a reduction in coating film adhesion strength, caused by fluctuations in the amount of plasma generated in the microwave plasma processing device. An object of the present invention is to provide a bond strength management method and device. Based on the confirmation that there is a correlation between the coating film adhesion strength, that is, the amount of plasma generated, and the plasma emission phenomenon, the present invention monitors the intensity of the plasma emission spectrum or the amount of light emission during plasma processing, and detects its fluctuations. The above objective was achieved by detecting.

FIG. 1 shows an apparatus for experimentally confirming the correlation between the relative spectral intensity and coating adhesion strength in such plasma emission. That is, 1 is a microwave oscillator, 2 is an isolator, 3 is a power monitor, 4 is a matching device, 6 is a gas cylinder filled with processing gas, 7 is a gas liquid meter, and 10
1 is a plasma generation furnace that generates microwave plasma by adding microwaves supplied through waveguide 5 to processing gas supplied through pipe 8; 11 is a quartz tube that transmits the microwave plasma; 12 is a Teflon joint. , 13 is a reaction chamber evacuated by a vacuum pump (not shown) through an exhaust port 14, and 15 is a reaction chamber 13.
This is a plasma irradiation tube that irradiates plasma onto the object to be processed.

Although the plasma processing apparatuses 1 to 8 and 10 to 15 themselves are conventional, the quartz tube 7 of this apparatus is used to transfer the plasma to a spectral intensity measuring device 18 that displays plasma emission as spectral relative intensity after spectroscopy. An optical fiber 17 for transmitting light emission is attached.

On the other hand, a test piece to be coated after plasma treatment and to measure the strength of the coating film is manufactured as follows. That is, the polypropylene flat plate molded product 22 was first suspended in a trichloroethane steam bath for cleaning, exposed for 2 minutes, then lifted and dried, and then subjected to plasma treatment under various conditions using the apparatus shown in FIG. Then apply urethane paint to 5081. After painting and drying at 120°C for 30 minutes, cut out a 50 x 10 mm piece from the center. To test the adhesion strength of the coating film on the test piece, as shown in FIG. 2, the coating film 20 was peeled off with a knife over a 1 cm length in the longitudinal direction, and after being sandwiched with cellophane tape 21, the coating film 20 was peeled off. The flat molded product 22 and cellophane tape 21 were fixed to the chuck of a tensile tester, and the test was conducted at a tensile speed of 50 mm/11 inch.

Next, the relative spectral intensity and coating film adhesion strength of the plasma emission confirmed by the above-mentioned plasma processing apparatuses 1 to 8, 1O to 15 and the plasma emission spectral intensity measuring device 17.18 and the above-mentioned strength test method for the test piece are as follows. We will explain the experimental results of the correlation between

Prior to plasma processing of the polypropylene flat plate molded product 22, in order to confirm the reproducibility of the emission spectrum, the processing gas was dry air with a constant flow, the output power of the microwave oscillator was IKW, and the vacuum degree of the processing chamber 13 was I Torr and 4
The emission spectrum at Torr was measured twice (Fig. 3 a, b, Fig. 4 a, b). From the emission spectrum, the wavelengths are 320nm, 345nm, 380nm,
A spectrum having a maximum value near 600 nm and 137 onm was selected, and the relative intensity of the emission spectrum was determined by the baseline method (Table 1).

As a result, the difference in the relative intensity of the emission spectrum at each wavelength between the first and second times is 0~5.8%, and good reproducibility is obtained, and the relative intensity of the emission spectrum is constant based on the settings of the predetermined input system. It can be seen that

In order to confirm the correlation between the relative intensity of the emission spectrum and the adhesion strength of the coating film, the polypropylene flat plate molded product 22 that had been cleaned with chloroethane steam was heated using a microwave oven, treatment time: 30 seconds, and treatment gas. : Under dry air conditions, the degree of vacuum in the reaction chamber 13 was set to 0.5, 1.4, and 8 T.
First, the relative intensities of the emission spectra I and R as shown in FIGS. Table 2 shows the wavelength 320.345.3 [fo
, 600 and 87 Or+m, and the test results of coating film adhesion strength corresponding to these plasma emission states conducted by the method described above are also shown.

Table 2 Figures 6a, b and c show the correlation between the maximum relative intensity of the emission spectrum near wavelengths 320.345 and 360 nm and the coating film adhesion strength based on these measurement and test results. From the relationship shown in FIG. 6, it can be seen that with respect to the emission spectrum in the ultraviolet region, the coating film adhesion strength becomes constant at a relative intensity of 0.08 to 0.14 and thereafter becomes constant, and below that, it rapidly decreases. Similarly, in Figures 7a and b, 600 and 6? The correlation with the maximum emission spectrum near Onm is shown. From the relationship shown in FIG. 7, it can be seen that in the visible region, the relative intensity increases sharply at approximately 0 and then becomes constant.

From the relative relationship between the plasma emission spectrum relative intensity and the paint film adhesion strength confirmed as shown below, the relative intensity of the emission spectrum for a specific wavelength can be monitored, and the fluctuation from the reference level can be monitored to determine whether the paint film has adhered. It can be seen that fluctuations in intensity can be detected. Further, since a change in the relative intensity of the emission spectrum means that it corresponds to a change in the absolute value of the intensity of the emission spectrum, the absolute intensity may be measured. As can be seen from Fig. 5, the relative intensity of the emission spectrum varies at the same rate over the entire emission wavelength range, so it is not necessary to intentionally select the wavelength to be monitored. It is sufficient to measure the total amount of light emitted over a certain wavelength range.

Next, an apparatus for carrying out the method according to the invention will be described.

In FIG. 8, 30 is a holding circuit that analogically holds the maximum emission spectrum intensity signal at a specific wavelength, for example, around 320 nm, of the emission spectrum intensity measuring device 18 of FIG. The relative intensity of the emission spectrum to ensure that the intensity is kept at a constant level, e.g. 0.1
A comparator that detects a change in the output signal of the holding circuit 30 in a downward direction from a reference level corresponding to 5, and an alarm device 32 that is activated by the output signal of this comparator to issue a warning by sound or optically. It is. That is, a comparator 31 monitors the output signal of a holding circuit 30 following an emission spectrum intensity measuring device 18 as a plasma luminescence measuring device, and when the signal falls below a reference level, an alarm is issued by an alarm 32, thereby detecting plasma generation. Abnormal reductions in the amount of plasma can be detected, and abnormalities in the plasma processing equipment can be immediately checked. When an optical layer measuring device is configured with a microcomputer equipped with an A/D converter on the input side and a D/A converter on the output side instead of the holding circuit 30 and the spectral intensity measuring device 18, the emission spectrum in a specific wavelength range can be measured. It becomes possible to compare the integrated value of intensity, or the average or integrated value for a plurality of wavelength ranges, with a reference level. Furthermore, the reference level is set to correspond to the arbitrary coating film adhesion strength in the scallop area in Figure 6a, and the comparator detects fluctuations in the emission spectrum intensity signal in the direction of increase or decrease by a predetermined amount from this reference level. By detecting it, you can control the adhesion strength to any desired range.

In FIG. 9, the optical fiber 17 in FIG. 1 is followed by a photoelectric conversion circuit 35, a comparator 36, and an alarm 37 as a plasma luminescence measuring device that outputs an electrical signal at a level corresponding to the incident light. In this case, by measuring the correlation between the output signal level of the photoelectric conversion circuit 35 and the coating film adhesion strength in advance, and setting the reference level of the comparator 36 slightly according to the result, the spectral intensity can be increased. There is no need to measure , making the device simpler and cheaper.

By feedback-controlling the error signal for the reference level 1 of the emission spectrum intensity or the amount of light emission to the input parameter system for setting the amount of plasma generation, servo control to keep the intensity of the emission spectrum or the luminescent liquid constant is also possible.

As described above, according to the present invention, by monitoring fluctuations in plasma emission spectrum intensity or luminescence amount when implementing a coating method involving microwave plasma pretreatment, it is possible to easily reduce the adhesion strength of a coating film caused by fluctuations in plasma generation amount. It becomes possible to manage the coating film adhesion strength to reliably prevent deterioration or ensure the desired adhesion strength with precision. That is, abnormalities in plasma processing can be detected with high reliability during processing, and defects in the object to be processed can be reliably prevented. Furthermore, if necessary, it becomes possible to automatically control the plasma generator based on the adhesion strength.

[Brief explanation of drawings]

Figure 1 shows a schematic configuration of a plasma treatment device and a plasma emission spectrum measuring device according to the present invention, and Figure 2 shows a method for testing the adhesion strength of a painted specimen after being plasma-treated with the device shown in Figure 1.2 Opening of the Park , Figures 3 and 4 are measurement results for confirming the reproducibility of the relative intensity of the plasma emission spectrum generated by the apparatus shown in Figure 1, and Figure 5 is based on Figure 1). Figures 6 and 7 are the measurement results of the relative intensity of the plasma emission spectrum when the temperature was varied, and Figures 8 and 9 are the experimental results of the correlation between the relative intensity of the plasma emission spectrum and the coating adhesion strength. 1 shows an apparatus for carrying out the method according to the invention. 1...Microwave oscillator, 6...Gas cylinder lO・
...Plasma generation reactor, 1? ...Optical fiber 13...
・Reaction chamber, 14... Exhaust port representative Masaharu Fukutome C) E SuA Materials collection m- Hibiki Tsuyoshi! ! IΦ-Ikkou Kishakuryo Mawari〈- (a) 1111Uichiomebun1tatableka1 Figure 7(b) -One relative strength

Claims (2)

[Claims] (1) In a method for treating variations in the adhesion strength of a coating film on an object to be coated formed by coating with microwave plasma pre-treatment, the emission spectrum intensity or luminescence amount of plasma for applying microwave plasma treatment to the object to be coated. A method characterized in that a change in coating film adhesion strength is detected based on a change in the intensity of the emission spectrum or the amount of light emission. (2) Emission spectrum intensity of microwave plasma provided between a plasma generation furnace that generates microwave plasma by supplying processing gas and microwaves to a evacuated reaction chamber that houses the object to be coated. Alternatively, a plasma luminescence measuring device for measuring the amount of luminescence is used, and the output signal of this measuring device is detected to fluctuate from a base wall level set at f, which corresponds to the emission spectrum intensity or the amount of luminescence that produces a predetermined coating film adhesion strength. This is an intensity control device for controlling the intensity of a coating film in a coating method that involves plasma pretreatment, which is characterized by a comparator and an alarm activated by the detection signal of the comparator.