JPS60250915A - Removal of adhesive matter on mold - Google Patents

Abstract

PURPOSE:To remove adhesive material sticking firmly to a mold surface remarkably easily and completely by irradiating ultraviolet rays on the adhesive material depositing on the mold in molding thermoplastic resin. CONSTITUTION:In molding thermoplastic resin composite containing polyacetal resin, when adhesive matters depositing on the mold in a molding time are removed, electromagnetic ultraviolet rays containing wave length 100-450nm are irradiated on the adhesive matters stuck firmly to the mold surface to remove them easily. Additionally, before or after the irradiation of ultraviolet rays, the adhesive matters on the mold are wiped off by cleaning water diffused or molded by the use of resin of the same kind or a different kind to transfer the adhesive matters on the mold to the molded piece and to be released from the mold. Therefore, the thermoplastic adhesive matters stuck to the mold are removed easily or can be removed completely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention makes it possible to extremely easily remove mold deposits, that is, mold deposits that adhere to the mold surface during molding of a thermoplastic resin or its composition. This invention relates to a method for removing deposits from molds.

[Prior art and problems to be solved by the invention] Molding of thermoplastic resins or their compositions is usually done by injection molding,
It is made by blow molding or extrusion molding. However, during molding, a phenomenon occurs in which the gas generated during repeated molding solidifies, or the compounds contained in the composition precipitate, and these adhere to the surface of the mold used for molding. . There is a problem that this impairs the dimensional accuracy of the molded product, is transferred to the surface, impairs the appearance of the product, or causes defective release from the mold.Therefore, conventional methods for removing such mold deposits have been proposed. Although various studies have been made, no satisfactory method has yet been found. In other words, the methods that currently create a film include applying cleaning liquid to the mold and then wiping off the deposits using cloth or absorbent cotton, or applying cleaning liquid and then molding under normal molding conditions to remove the deposits. However, the cleaning liquid itself has poor cleaning properties and is particularly ineffective against deposits such as paraformaldehyde adhering to the mold during polyacecool resin molding. In addition, manual wiping requires a great deal of labor and time, and it is impossible to completely remove deposits down to the smallest detail in complex molds used for precision molding of gears, etc. This is difficult and may damage the mold during wiping. Furthermore, special agents, i.e., solvents containing fluorine-containing ketones, alcohols, ethers, esters, hydrocarbons, etc.
For example, a solution prepared by dissolving mono-hexafluoroacetone, mono-hexafluoropropertool, etc. in an appropriate alcohol, ketone, ester, ether, or other liquid has a strong cleaning power for mold deposits, and It is possible to effectively remove such substances by applying or spraying them on the deposits and wiping them off with a cloth or by molding them, but such substances are generally expensive, may corrode the mold, and The use of such solvents is often inappropriate because some of them are harmful or unpleasant to the human body. Therefore, when molding thermoplastic resins, how to completely and efficiently remove the deposits during molding is an extremely important issue in terms of the quality of molded products and work efficiency.

[Means for Solving the Problems] Therefore, the inventors of the present invention set out to find an effective method for removing mold deposits that can solve the above problems (as a result of repeated studies, we found that using ultraviolet energy They have found that it is extremely effective to utilize this method, and have arrived at the present invention.

That is, the present invention provides a method for removing mold deposits deposited on the surface of a mold used in molding a thermoplastic resin or a composition thereof, such as polyacecool resin or a composition thereof. This is a method for removing mold deposits, which is characterized by carrying out the following steps.

By irradiating ultraviolet rays as described above, deposits deposited on the mold during molding can be removed easily, even if they are extremely firmly adhered, or by wiping them off with cloth, paper, cotton, etc. with a known cleaning solution applied. It can be removed.

In addition, it was confirmed that even without wiping after irradiation with ultraviolet rays, the deposits could be completely transferred to the molded product and removed from the mold within an extremely small number of molding cycles by continuing to mold the product. Ta.

The ultraviolet rays used in the present invention are 100 to 450 nm (
nm: nanometer, lnm = 10 meters), in other words, it is an electromagnetic wave that has a wavelength between X-rays and visible light, and includes so-called near ultraviolet rays and far ultraviolet rays.
It is an electromagnetic wave with a wavelength that falls within the range between them. As a generator (ultraviolet light bulb) of ultraviolet rays of such wavelength,
All devices that emit ultraviolet (UV) radiation can be used, such as hydrogen discharge tubes, xenon discharge tubes, mercury lamps, germicidal lamps, and powerful fluorescent lamps. The wavelengths in these ultraviolet generators are slightly different, but as long as they include wavelengths of 100 to 450 nm as mentioned above, there is no problem with the effect even if other long wavelengths are included, but in general, long wavelengths As the wavelength increases, the removal effect of mold deposits decreases,
Visible light or infrared rays whose wavelengths are all 450 nm or more have almost no effect no matter how powerful the light source is.

On the other hand, on the short wavelength side of 1100n or less, the effect itself is probably strong, but the negative effect on the human body etc. cannot be ignored, and taking this point into consideration, 1100n is recognized as the lower limit of the wavelength. Particularly effective wavelength range is 200~400nn+
Irradiation with a wavelength in this range is generally an effective range for ozone generation, and it is understood that the chemical action caused by this also promotes the effects of the present invention.

In the present invention, the effect of removing deposits deposited and fixed on the mold naturally depends on the quality of the deposits, the amount of deposits depending on the number of moldings, etc., but if the deposits are of the same quality and quantity, it may be used. Conditions such as the output of the ultraviolet light source, distance, and irradiation time affect the removal effect. The output of the ultraviolet lamp used in the method of the present invention is not particularly limited, but 2000 watts or less is sufficient. However, a lamp with too low output requires long irradiation, which is not desirable in terms of work efficiency. Generally speaking, if the irradiation time is about 1 to 10 minutes, the output will be approximately 100 to 1000 watts, although it depends on the quality and quantity of deposits, and a distance of 50 cm or less from the light source is appropriate.

The output of the light source is low and the effect is insufficient for irradiation from a long distance, for example, the output and distance conditions of indoor fluorescent lamps are insufficient.

Naturally, the shorter the exposure time, the shorter the distance from a high-output ultraviolet lamp is sufficient. Therefore, in order to remove a large amount of hard deposits from a mold, remove the insert containing the mold or cavity from the molding machine and set it close to a high-output ultraviolet lamp. Although it is desirable to use ultraviolet irradiation, it is generally not desirable for work efficiency to remove molds during the production of a large number of molded products, so in such cases, a portable ultraviolet lamp is used to attach molds, etc. It is also possible to irradiate directly. Portable types are generally small and have a low output, but depending on the degree of adhesion, they are often advantageous in terms of work efficiency in that they do not require removal of the mold if done at the right time. However, which one to select depends on the situation and is of course arbitrary. In either method, the method of the present invention has significant advantages in terms of reliability of removing deposits and work efficiency compared to conventional cleaning methods that do not use ultraviolet light.

In the present invention, the removal of deposits after ultraviolet treatment may be carried out by a conventional method. That is, it can be easily removed by wiping with paper, cotton, cloth, etc. At this time, the deposits can be removed more easily by spraying the deposits with a conventionally known cleaning solution or by impregnating a cloth or the like and wiping the deposits.

In addition, even without wiping with a cloth, molding using the same or different type of resin after irradiation with ultraviolet rays can remove dirt on the mold during a small number of molding cycles (for example, one to several times). It is also possible and convenient to remove the deposits by completely transferring them to the molded product and removing them. That is, for example, by restarting molding immediately after irradiation with ultraviolet rays and excluding only the first one to several molded products, normal molded products can be obtained thereafter, and production can be continued efficiently. In this case as well, it is generally more effective to spray or apply a cleaning liquid to the deposits on the mold before or after irradiation, and then perform molding.

Note that the cleaning agent mentioned here is generally a liquid that has the ability to dissolve, swell, and permeate deposits related to the resin component to be molded, and for example, it is a liquid that has the ability to dissolve, swell, and penetrate deposits related to the resin component to be molded. For deposits containing formaldehyde, especially alcohols, ethers, ketones, esters, aliphatic and aromatic hydrocarbons, alicyclic compounds, and their halogen derivatives, An organic cleaning solution containing two or more types is effective. Specific examples of these substances are given in Japanese Patent Application No. 58-7.
It is described in detail in No. 7999.

[Function] The effect of removing mold deposits in the method of the present invention is that by irradiating high-energy electromagnetic waves such as ultraviolet rays, the deposits decompose, disintegrate, or become brittle, and at the same time, the adhesive force to the mold disappears. It is understood that this makes it easier to peel off from the mold.

In addition, the temperature conditions are arbitrary and do not need to be specified in the implementation of the present invention, but in general, the temperature rises due to ultraviolet irradiation, and especially when using a high-output ultraviolet lamp, the temperature will be high. There is also the possibility of chemical auxiliary effects due to ozone generation. However, the essential requirement of the method of the present invention is the irradiation of ultraviolet rays, and the main effect is due to this, for example,
It has been confirmed that when an incandescent lamp or an infrared lamp with a long wavelength of nm or more is used, a temperature rise occurs, but there is almost no removal effect.

[Effects of the Invention] The effectiveness of the present invention in removing mold deposits has been described above and is believed to be clear from the Examples described below, but the effects over the conventional method can be summarized as follows.

1. Mold deposits from molding can be removed more completely, and the dimensional accuracy of molded products can be maintained at an even higher level.

2. Mold deposits can be removed more easily and in a shorter time than before, significantly improving work efficiency and increasing productivity.

"Example" Examples of the present invention are listed below, but the present invention is not limited thereto.

II 1.2 and aJ Genkajou polyacecool resins are used under harsh molding conditions (especially when mold deposits are likely to form in the mold cavity).
After 30,000 shots of a specific shape were molded by repeated molding at a resin temperature of 230°C and a mold temperature of 20°C, the mold with a large amount of mold deposit was heated with a high-pressure mercury lamp (IIOW/cm). , type with argon gas and mercury sealed in the arc tube, wavelength 250nm ~ 40nm
Ultraviolet irradiation was carried out under the conditions shown in Table 1 using UV light (0 nm), and then various methods were used to try to remove the deposits. Table 1 also shows the removal status of deposits.

For comparison, Table 1 also shows a case where the same treatment was performed without UV irradiation.

Back 3 and 12.3 Using polyacecool resin, repeated molding was performed under harsh molding conditions where mold deposits similar to those in Example 1.2 were likely to be deposited, and molding was temporarily interrupted when molding reached io and ooo shots. However, the mold with this precipitate attached was irradiated with ultraviolet light using an ultraviolet lamp under the conditions shown in Table 2, and then an attempt was made to remove the deposit using the method shown in Table 2. . The results are also shown in Table 2.

For reference, Table 2 also shows the case of irradiation and heating with an infrared lamp of the same output.

Claims (1)

[Scope of Claims] 1. A method for removing deposits deposited on a mold during molding of a thermoplastic resin, which comprises irradiating ultraviolet rays to remove deposits deposited on the mold during molding. 2. The method for removing mold deposits according to claim 1, wherein the thermoplastic resin is a composition containing polyacecool resin or polyacetal resin. 3. The method for removing mold deposits according to claim 1 or 2, wherein the ultraviolet rays are electromagnetic waves having a wavelength of 100 to 450 nm (nm: nanometer, lnm = 10 meters). 4. The method for removing mold deposits according to any one of claims 1 to 3, wherein a cleaning liquid is applied or sprinkled on the mold deposits prior to ultraviolet irradiation. 5. After irradiation with ultraviolet rays, molding is performed using the same or different type of resin, and mold deposits are transferred to the molded product and removed from the mold. The described method for removing mold deposits. 6. The method for removing mold deposits according to claim 5, wherein a cleaning liquid is sprayed or applied to the deposits on the mold after ultraviolet irradiation and before molding. 7. The method for removing mold deposits according to any one of claims 1 to 4, which comprises wiping the deposits with cloth, paper, or a piece of paper using a cleaning solution after irradiation with ultraviolet rays.