JPS59202298A - Method of removing metal mold adherent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing mold deposits that can extremely easily remove mold deposits that adhere to the mold surface during molding of a thermoplastic resin composition. .

Molding of thermoplastic resin compositions is usually performed by injection molding or extrusion molding. However, during molding, a phenomenon occurs in which gases generated during molding harden or compounds contained in the composition precipitate and adhere to the surface of the mold used for molding.

Then, there is the problem that it is transferred to the surface of the molded product, impairing the appearance and dimensional accuracy of the product, or causing poor mold release.
Although various studies have been made on methods for removing such deposits from molds, 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. In addition, manual wiping requires a lot of effort, and it is difficult 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 when wiping it off.

Therefore, the inventors of the present invention have conducted repeated studies to find an effective method for removing mold deposits that does not have such drawbacks.
The present invention has been made based on the fact that the application of ultrasonic cleaning is extremely effective.

That is, the present invention provides a method for removing mold deposits adhering to the surface of a mold used for molding a thermoplastic resin composition, such as a polyacecooled resin composition, using an organic cleaning liquid,
In particular, ultrasonic cleaning is performed using an organic cleaning liquid containing one or more of alcohols, ethers, ketones, esters, aliphatic and aromatic hydrocarbons, alicyclic compounds, and their halogen derivatives. This is a method for removing deposits from a mold.

This will be explained in detail below.

Alcohols include aliphatic and aromatic hydrocarbons, alicyclic compounds, and other saturated and unsaturated monohydric alcohols, dihydric alcohols, polyhydric alcohols, and the like. The alkyl group of the saturated aliphatic and dihydric alcohol preferably has 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms. Examples of these include methanol, ethanol, flobyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, eec・〜butyl alcohol, tθrt−
These include butyl alcohol, ethylene glycol, propylene glycol, trimethylene glycol, 1.2-butanediol, 1,5-butanediol, 1,4-butanediol, 2,3-butanediol, isobutylene glycol, and the like. Examples of aromatic alcohols include benzyl alcohol and cinnamyl alcohol. Examples of alicyclic alcohols include cyclopentanol and cyclohexanol.

Ethers include aliphatic and aromatic hydrocarbon compounds,
These are mono- or mixed ethers such as cyclic compounds. Preferred ethers are those in which one of the two hydrocarbon residues has 1 to 6 carbon atoms, particularly preferably 3 to 4 carbon atoms. Examples of ethers include propyl ether, butyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, and dioxane.

The esters are preferably esters of organic acids or organic carboxylic acids. Examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate,
Examples include isobutyl acetate and nibutyl acetate, with ethyl acetate being particularly preferred.

Ketones include saturated and unsaturated aliphatic and aromatic hydrocarbons, alicyclic compounds, and the like. The aliphatic saturated ketone preferably has two hydrocarbon residues having 1 to 6 carbon atoms. Examples include dimethyl ketone, ethyl methyl ketone, diethyl ketone, methyl flobyl ketone, inopropyl methyl ketone, butyl methyl ketone, ethyl propyl ketone, isobutyl methyl ketone, methyl-n-hexyl ketone, methyl-n-amyl ketone, These include ethyl-n-butyl ketone, di-n-propyl ketone, diisobutyl ketone, dimethyl oxide, and holon. Ketones of alicyclic compounds include inphorone, cyclohexanone, methylcyclohetisanone, acetophenone, and the like.

Examples of aromatic compounds based on carbonized silica include benzene, toluene, ethylbenzene, flobylbenzene, isopropylbenzene, n-7' thylbenzene, isobutylbenzene, θθC-butylbenzene, tθI・1-nibutylbenzene, xylene, and ethyl. Chills such as methylbenzene and diethylbenzene, particularly benzene, are preferred. Aromatic phenols and aromatic amines can also be used.

In addition, hydroxyketones having a carbonyl group and a hydroxyl group in the molecule, such as diacetone alcohol, dimethylformamide as an amide, and γ-butyrolactone as an aliphatic compound, can also be used as halogen derivatives such as halogenated hydrocarbons. Examples of chloromethane, dichloromethane, tetrachloromethane, trichloroethylene, tetrachloroethylene, chlorobenzene,
These include dichlorobenzene and trichlorobenzene. Particularly preferred are tetrachloromethane and trichloroethylene. These cleaning solutions can be used alone or as a cleaning solution containing a mixture of two or more compounds. Give an example of a cleaning liquid made by mixing two or more types.C. Ethyl methyl ketone-methyl alcohol, ethyl methyl ketone-isopropyl alcohol, ethyl methyl ketone-benzyl alcohol, isopropyl alcohol-benzyl alcohol, Inflobil alcohol-ethylene glycol, Inflobil alcohol-ethylene glycol, Inflobil alcohol-ethylene glycol, Byl alcohol-glycerin, benzyl alcohol-ethylene glycol, benzyl alcohol-1,4-butanediol, benzyl alcohol-ethyl alcohol, ethyl alcohol-glycerin, etc. They are appropriately selected and used depending on the ultrasonic cleaning conditions. For example, if the mold deposits are low-molecular-weight polyacetals that are difficult to clean, use a swelling cleaning solution or a solubility parameter (commonly known as SP value).
It is preferable to use a cleaning liquid containing a compound in which the parameter ) is similar to polyacetal, such as ethyl methyl ketone or trichlorethylene, but no cleaning effect will be observed if kerosene or the like which is not similar is used. Further, when the mold deposit is a compound contained in the polyacetal composition, a cleaning liquid that dissolves the compound is used.

The ultrasonic cleaning used in the present invention is a method of physically and chemically cleaning items in the liquid by applying ultrasonic vibrations to the cleaning liquid. The material attached to the article is removed by mechanical force when the cavity is destroyed. According to the present invention, there are no particular limitations on the frequency and cleaning time of the ultrasonic waves, but typically a frequency within the range of 20 to 30 KHz is used to clean the ultrasonic waves.
Cleaning is performed for about a minute.

To actually carry out the present invention, it is sufficient to remove the nest installed in the mold cavity, immerse it in the above-mentioned cleaning liquid, and perform ultrasonic cleaning. If the temperature of the cleaning solution increases due to ultrasonic cleaning, it is best to use a container that can cool the cleaning solution, and if the cleaning solution volatilizes, use a container that can collect the volatile matter by cooling and condensing it. It is better to use However, it would be preferable to use a cleaning liquid containing a compound with a high boiling point, or a cleaning liquid mixed with another compound that increases the boiling point. In addition, stabilizers may be added to the cleaning solution because the cleaning solution will be used for a long time.Furthermore, if a cleaning solution that is concerned about corrosiveness of the mold is used, after cleaning, use a non-corrosive cleaning solution to further stabilize the cleaning solution. It is a good idea to perform sonic cleaning. On the other hand, the same effect can be observed even if the nest is immersed in a cleaning solution for a certain period of time and then subjected to ultrasonic treatment, or even if it is washed after being irradiated with ultrasonic waves. In addition to the immersion ultrasonic cleaning method, even if the mold is too large to be immersed, it is possible to apply or spray a cleaning solution on the mold as soon as it is attached to the molding machine. Ultrasonic cleaning can be performed when ultrasonic waves can propagate through the liquid.

Examples of the present invention are shown below.

Examples 1 to 14 Injection molding using PoIJ 7 setal resin (Duracon manufactured by Polyplastics Co., Ltd.) Resin temperature: 19D
C, 150,010 molded products with a specific shape at a mold temperature of 6DC
When a 00 shot was molded, a large amount of highly viscous, tar-like mold deposits adhered to the nest in the mold. Thereafter, the nest was removed and immersed in the cleaning solution shown in the table for ultrasonic cleaning. Cleaning time is 2 minutes, frequency used is 3
0 KHz, temperature is room temperature. The results are shown in the table below.

(Note) Value in parentheses: Weight % > In the same solvent used as the cleaning solution in the Raku example, the insert with mold deposits adhered to it was immersed and wiped off without ultrasonication. It took a lot of effort to remove it and was not very effective.

As is clear from the above results, in the present invention, by performing ultrasonic cleaning using a specific cleaning solution, Simold deposits can be removed extremely easily and almost completely due to the synergistic action of the two. . Therefore, it is possible to easily solve the problems that have hitherto been caused, such as transfer of deposits to the surface of molded products, damage to the dimensional accuracy of precision parts, and defective mold release.

Applicant's agent Kaoru Furutani

Claims (1)

[Claims] 1. A method for removing mold deposits adhering to the surface of a mold used for molding a thermoplastic resin composition, characterized by performing ultrasonic cleaning using an organic cleaning liquid. How to remove mold deposits. 2. The method for removing mold deposits according to claim 1, wherein the thermoplastic resin is particularly a polyacetal resin. 3. Alcohols, ethers, ketones, esters, aliphatic and aromatic hydrocarbons,
3. The method for removing mold deposits according to claim 1 or 2, which uses a cleaning liquid containing one or more types of alicyclic compounds and their halogen derivatives.