KR910005008B1 - How to remove the mold attachment - Google Patents

Abstract

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Description

How to remove the mold attachment

The present invention relates to a mold deposit cleaning liquid that allows easy removal of mold deposits formed on the surface of a mold during molding of the thermoplastic resin composition, and to a method of removing such deposits in which the cleaning liquid is used.

The prior art is described as follows.

Molding of the thermoplastic resin composition is usually carried out by injection molding or extrusion. One problem experienced with molding is that the gases generated during the molding operation either solidify or the compounds contained in the composition detach and adhere to the surfaces of the molds they used in molding.

These attachments are easy to move on the surface of the part and often impair the appearance or dimensional accuracy of the product or cause sticking of the parts of the mold. Various attempts have been made to remove such molding deposits, but no satisfactory method has yet been found.

Currently common methods include applying a cleaning solution to a mold and then wiping it with a cloth or absorbent cotton and another method of applying the cleaning solution and then performing the molding under ordinary molding conditions and then removing the deposits. However, the cleaning liquid itself does not have sufficient cleaning properties, and the liquid is not so effective, especially when it is accompanied by an attachment such as paraformaldehyde as in the case of molding a polyacetal composition.

Moreover, wiping requires considerable effort, and in the case of complex mouldings such as those used for precision cleaning for gears, etc., it is difficult to remove enough of the deposits present in the details and sometimes the mold may be damaged during wiping. have.

If a solvent is used that is strongly alkaline, acidic, or contains oxidant components, deposit removal may be much easier, but such solvents are not suitable for use because they are susceptible to corrosion or damage to the mold surface.

In summary, the present invention is as follows.

Therefore, the present inventors conducted extensive research to find a cleaning liquid that can effectively remove the mold deposits, and as a result, the present invention has been achieved.

In a method for removing deposits from the surface of a mold for thermoplastic resin with a cleaning liquid, the present invention provides an advance that the cleaning liquid is an organic cleaning liquid containing a lactone compound therein.

The invention also provides a cleaning liquid composition consisting of 5 to 50% by weight of lactone, 9 to 95% by weight of alcohol and the remainder consisting of water or an organic solvent.

In other words, the present invention relates to a method for removing a mold of a thermoplastic resin composition such as a polyacetal resin composition comprising, for example, lactone, and more specifically, an organic cleaning solution containing lactone and an alcohol.

Lactone is, here, an essential component of the cleaning liquid used in the present invention, wherein the number of atoms constituting the cyclic ester including ester-CO-O- functional group and its derivative, ie, ring containing ester group, is 4 to 4 in its ring. The substance which is 6, or (beta) -lactone (4-membered ring), (gamma) -lactone (5-membered ring), and (delta) -lactone (6-membered ring), and its derivative (s) are mentioned. Examples of these substances include β-propiolactone, γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprylolatone, γ-laurolactone, γ-palmitolactone, γ-stearo Lactone, crotolactone, α-angelicalactone, β-angelicalactone, δ-valerolactone and δ-caprolactone.

The amount of lactone used in the present invention is at least 5% by weight, preferably 10 to 50% by weight based on the entire cleaning liquid. Such lactones may be used in admixture with other organic solvents. Most suitable for this use as other organic solvents are alcohols.

Here, alcohol refers to saturated and unsaturated aliphatic and aromatic hydrocarbons, monovalent, divalent and polyhydric alcohols, alicyclic compounds and the like.

Preferred saturated aliphatic monohydric and dihydric alcohols have 1 to 6 carbon atoms and more preferably 1 to 4 carbon atoms in their alkyl group. Examples of these alcohols are methanol, ethanol, floppy alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol and isobutylene glycol. Examples of aromatic alcohol compounds are benzyl and cinnamil alcohols. Examples of cycloaliphatic alcohols are cyclopentanol and cyclohexanol.

In addition, lactones may be used in the form of a mixture comprising one or more other solvents such as water, ethers, ketones, other esters, aromatic hydrocarbons, or other halogen derivatives. The cleaning solution is particularly effective when it contains both lactone and alcohol, in which case the proportion of alcohol is 5 to 95% by weight, preferably 50 to 90% by weight, based on the entire cleaning solution.

In order to remove the mold deposit by using the cleaning liquid according to the present invention, any known general practice can be used. For example, the adherent present in the mold can be wiped off with a cloth, paper, etc., moistened with the inventive cleaning solution (in this regard, any suitable varnish powder can be used in combination with the liquid), or the mold surface on which the adherent is present. After applying the cleaning solution to the mold, the molding is repeated to move the deposit on the molded part so that the deposit can be removed from the mold surface or the above two methods can be used in combination.

With any other removal method, the inventive cleaning liquid can also be used effectively.

Advantages of the invention are as follows.

The method of removing mold deposits by using an organic cleaning solution comprising lactones according to the invention does not involve the possibility of corrosion or damage to the mold, and may be alcohols, ethers, ketones, other esters, water, or mixtures of two or more thereof. This allows for easier removal of deposits compared to conventional methods using conventional organic solvents that do not contain lactones such as.

For example, when wiping a deposit on the mold surface with a patch moistened with a cleaning solution, the required number of wipes may be reduced until the original clean surface is restored, or the liquid is applied onto the mold attachment to remove the deposit. The molding can be repeated to reduce the number of moldings and the time required when moving the deposits on the mold.

In general, the removal of mold deposits according to conventional methods may be easier with higher molding temperatures, but increasing the molding temperature requires longer time to stop a series of molding operations, affecting production efficiency.

However, according to the method of the present invention using the inventive cleaning solution, even if the molding temperature is very low, the mold deposit can be removed. Therefore, the method of the present invention is also advantageous in production efficiency.

EXAMPLE

The following examples are provided to further illustrate the invention, but it should be understood that the invention is not limited to these examples.

[Examples 1 to 7 and Comparative Examples 1 to 10]

Ten thousand shots were formed from polyacetal resin (Duracon M 9002 Polyplastics) by injection molding under conditions of a resin temperature of 200 ° C and a molding temperature of 60 ° C. It was found on the att.

Next, the insert was removed and wiped off using a cloth (flannel) of 5 cm width and 4 times, evenly moistened with the cleaning solution shown in Table 1 without special heating.

The test was carried out in such a way that the one wiping operation was carried out under the same conditions every time as possible (ie, the mold surface was wiped twice with the same piece of cloth, and this was repeated once and the cloth was changed each time and the same operation was repeated). This glossiness factor was compared with respect to the required number of wiping cycles until the original clean condition was restored (method A).

The results are shown in Method-A column of Table 1.

In the cleaning liquids shown in Table 1 on the mold deposits for each test, the molding is carried out under the conditions as described above and without removal of the insert and without special heating with respect to the post-molding molds in which similar deposits are present. One minute and one minute afterwards, the cleaning test was performed by performing the molding operation, and the molding surface was repeated until the molding surface was restored to the original clean condition for factors such as gloss.

In this test method, a new coat is applied every five shots (Method B).

The results are shown in Method-B column of Table 1.

TABLE 1

[Examples 8 to 9 and Comparative Examples 11 to 14]

Injection molding was performed using polyacetal resin, Tenac-4010 (manufactured by Asai Chemical Industries Co., Ltd.) under slightly modified molding conditions (resin temperature 210 ° C, molding temperature 80 ° C).

The test was carried out in exactly the same manner as in the above-described Examples and Comparative Examples by using the cleaning conditions shown in Table 2.

The results are shown in Table 2.

TABLE 2

[Examples 10 to 11 and Comparative Examples 15 to 17]

20,000 shots were formed from flame retardant polyester resin Duraned 3370 (polyplastic product) by injection molding under the conditions of resin temperature of 250 ° C and molding temperature of 60 ° C. It was found that there was a mold attachment. The wiping test was carried out in a similar manner to Method A of Examples 1 to 7 without heating the mold in particular. The results are shown in Table 3.

TABLE 3

Claims (4)

A method for removing a deposit from a surface of a mold for thermoplastic resin with a cleaning liquid, wherein the cleaning liquid is an organic cleaning liquid containing a lactone compound therein. The method according to claim 1, wherein the cleaning liquid comprises alcohol and lactone. The method of claim 1, wherein the thermoplastic resin is polyacetal. The method of claim 1, wherein the washing solution is 5 to 50% by weight of lactone, 5 to 95% by weight of alcohol and the remainder is water or an organic solvent.