JPH066295B2 - Mold cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a molding die cleaning for cleaning a molding die such as a contaminated molding die for thermosetting resin molding material by repeating molding work. It is about the method.

[Conventional technology]

At the time of molding the thermosetting resin molding material, the release agent contained in the thermosetting resin molding material exudes to the surface of the mold to exert a releasing effect. When such molding is repeated, the mold releasability of the molded product is remarkably deteriorated, the surface of the molded product is roughened, and the surface of the molded product is not glossy. It is considered that this is because the release agent is sequentially laminated on the surface of the mold by repeated molding and gradually deteriorates due to oxidation to form an oxidative deterioration layer of a hard release agent. For example, as shown in FIG. 8, the molten epoxy resin molding material 6 is press-fitted into the cavity 3 formed by the upper mold 1 and the lower mold 2 of the transfer molding through the runner 5 by the pressing force of the plunger 4. After molding, the mold is opened and the molded product 7 is taken out as shown in FIG. When such a molding operation is repeated, the oxidation-deteriorated layer 7a of the release agent is formed in the cavity 3. Further, flash 8a also remains around the cavities of the mold seam 8 and the like. 9 is an air vent part. Once such an oxidative deterioration layer 7a of the release agent is formed on the cavity surface (mold surface), thereafter,
When molding the thermosetting resin molding material, the mold release agent oozing out from the molding material acts on the oxidation-deteriorated layer 7a of the mold release agent rather than on the mold surface, thus providing a sufficient mold release effect. It will not work.

[Problems to be Solved by the Invention]

In order to solve such a problem, conventionally, a thermosetting melamine resin molding material is put in the mold at the stage where the release agent oxidative deterioration layer 7a is formed (the stage after 700 to 1000 shots). By molding and curing, the mold release agent oxidation deterioration layer 7a on the surface of the mold is integrated with the molding product 7, and the molding product 7 with the oxidation deterioration layer 7a integrated is taken out from the mold, It is being cleaned. In this case, formalin is produced as a by-product as a condensate of the thermosetting melamine resin molding material to generate an odor and the like, which deteriorates the working environment and causes deterioration of cleaning workability.

When the surface of the mold is cleaned by using the thermosetting melamine resin molding material as described above, the mold surface is completely cleaned, so that the mold release agent does not exist at all on the mold surface. Therefore, when the molding material is molded in the state where the mold release agent does not exist on the mold surface as described above, the molded product adheres to the mold surface and is not smoothly released from the mold. This is because the mold surface is completely cleaned, and therefore the mold releasing agent does not sufficiently adhere to the mold surface due to the mold releasing agent oozing out from the molding material in a single molding process. Therefore, conventionally, a molding material is used so that the mold releasing agent is sufficiently adhered to the surface of the mold, and pre-molding is performed 2-3 times (this is referred to as a dummy shot), and the internal mold releasing agent contained in the molding material is molded. It is said that ordinary molding is performed after sufficient adhesion to the mold surface. However, it is extremely uneconomical to perform the dummy shots for a few shots in this way, and this causes a decrease in molding efficiency.

The present invention has been made in view of such circumstances, and the cleaning of the mold surface and the application of the release agent to the mold surface can be easily performed without deteriorating the work environment or performing dummy shots. Its purpose is to be able to do it.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the molding die cleaning method of the present invention includes a step of sandwiching a mold cleaning sheet having an unvulcanized rubber fabric as a base material between a pair of molding dies, and a pair of molding dies in that state. The step of cleaning the mold surface by operating the mold of No. 1, the step of removing the mold cleaning sheet from between the pair of molds after the molding operation, the pair of molds with the mold surface cleaned A step of sandwiching a release sheet containing an unvulcanized rubber material as a base material and a release agent between the molds, and in that state, a pair of molding dies is operated to form a release agent on the mold surface. And a step of providing.

[Action]

The present inventors have conducted a series of studies on the cleaning effect on the above-mentioned molding die, and as a result, in particular, using a sheet having an unvulcanized rubber material as a base material, and sandwiching it between molding dies to perform molding. When the mold is operated, the unvulcanized rubber material is vulcanized, and at the same time, the contaminant components on the mold surface are transferred into the vulcanized rubber, and the vulcanized rubber is removed from the mold. And found that the mold surface can be easily cleaned. In this case, when vulcanizing the unvulcanized rubber in the mold, there is no odor such as formalin odor or amino acid odor, and the problem of deterioration of working environment does not occur. In addition, as a result of repeated research on a mold whose surface has been cleaned in this way, after cleaning, it is possible to immediately start forming work without performing dummy shots. The base material is used as a base material, and a release sheet containing a release agent is sandwiched between molds with a clean mold surface, and when the molding operation is performed in the same manner as above, the mold surface is cleaned and mirrored. The mold release agent exudes from the unvulcanized rubber material and adheres to the mold surface, forming a uniform mold release agent film on the mold surface. The present invention has been reached by finding that the molding work can be immediately started. That is, by sandwiching the release sheet between the molds that have been cleaned, heat-molding once, and then peeling the sheet, a clean and mirror-shaped mold surface is obtained. On the other hand, the release agent film is uniformly formed. Therefore, the molding operation can be immediately started without performing the dummy shot, and the efficiency of the molding operation can be improved. Moreover, since the release agent application work is sufficient once, the work efficiency of the release agent application work can be significantly improved.

The molding die cleaning method of the present invention cleans the molding die by using two types of sheets, a mold cleaning sheet and a release sheet, but not only the surface of the molding die, The periphery of the molding die (around the cavity) is also contaminated by repeating the molding. In such a case, a cleaning sheet around the molding section is used for the purpose of cleaning only the cavity around the mold. Since the mold size of a molding machine for such three types of sheets varies depending on the manufacturer of the molding machine, the sheet itself is set to the maximum size among them, and the individual metal molds are set for use. Depending on the model, a mark that can be cut is put. That is, in each of these three types of sheets, as shown in FIG. 1, for example, marks 11 for cutting the sheet 10 into appropriate dimensions are provided at predetermined intervals. In FIG. 1, the mark 11 is formed by cutting, and the depth thereof is set to about 2/3 of the thickness of the sheet 10. Then, using the cut, the sheet 10
Can be cut to an appropriate size. The state of formation of this notch is shown in FIG. Instead of making a cut to about 2/3 as described above, a cut may be made to about half the thickness as shown in FIG.

Such notches may be formed using a ribbon slitter having disc-shaped cutting blades 13 at predetermined intervals on the rotary shaft 12 as shown in FIG. 4, or as shown in FIG. As described above, the embossing cutter having the abacus bead-shaped cutting blades 14 at appropriate intervals on the rotating shaft 12 may be used. Also, instead of making a notch as described above,
You may make a mark by printing. In this case, a knife or the like is used to cut along the mark. In addition, after printing, a cut may be made on the print. Further, the state of the mark is not limited to the grid pattern as shown in FIG. 1, and the parallel lines may be provided in only one direction, or the mark may be provided only at the peripheral portion of the sheet at regular intervals. You may When the marks are formed at regular intervals, the marks also have a function of media.

Next, among the above three types of sheets, a mold cleaning sheet for cleaning the mold surface of the molding mold will be described first.
This mold cleaning sheet uses an unvulcanized rubber material as a base material, and may be composed of only unvulcanized rubber material, but normally contaminants on the surface of the mold (oxidation of the release agent are used). A removal aid for blending the (degraded layer) smoothly from the mold surface is blended. There are two types of mold cleaning sheets composed of this type of removal aid and unvulcanized rubber fabric. The first one is based on an unvulcanized rubber material made of a mixture of glycol ethers represented by the general formula (1) and unvulcanized rubber.

[In the formula (1), n is a positive integer. R ₁ and R ₂ are hydrogen or an alkyl group, and when one is hydrogen, the other is an alkyl group, and when both are alkyl groups, they may be the same or different. ] The glycol ethers represented by the above general formula (1) include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl. Ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol propyl ether, diethylene glycol dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol Nobutyl ether and the like can be mentioned.

Among the glycol ethers represented by the above general formula (1), when n = 1 to ₂ and either R ₁ or R ₂ is hydrogen, the other is an alkyl group having 1 to 4 carbon atoms, and ,
When both R ₁ and R ₂ are alkyl groups, the number of carbon atoms is 1 to 1.
It is preferable that it is an alkyl group of 4. The above n
When the value is 3 or more, the compatibility with rubber is lowered, and when the alkyl group has 5 or more carbon atoms, the permeability of the release agent to the oxidative deterioration layer is deteriorated. A tendency will be seen.

The above glycol ethers may be used as they are, or may be mixed with water or an alcohol such as methanol, ethanol or n-propanol, or an organic solvent such as toluene or xylene. When mixed with an organic solvent, the amount of the organic solvent is usually 50 parts or less with respect to 100 parts by weight of glycol ethers (hereinafter abbreviated as “part”), and most commonly 20 parts or less. Is done. Further, a conventionally used release agent may be used in an appropriate amount, if necessary. When a release agent is used in combination, the amount used is 10 parts or less per 100 parts of the total amount of unvulcanized rubber fabric and glycol ethers, and most commonly 2 to 5 parts. Is done.

The unvulcanized rubber includes natural rubber (NR), chloroprene rubber (CR), butadiene rubber (BR), nitrile rubber (NBR), ethylene propylene terpolymer rubber (E
PT), ethylene propylene rubber (EPM), styrene butadiene rubber (SBR), polyisoprene rubber (I
R), butyl rubber (IIR), silicone rubber (Q),
It is possible to use, for example, one containing fluorine rubber (FKM) alone or a mixture as a main component, further containing a vulcanizing agent, and optionally a vulcanization accelerator and a reinforcing agent. This unvulcanized rubber is vulcanized into a vulcanized rubber in the mold. The above-mentioned unvulcanized rubber is preferably EPT, SB
R, NBR or a mixture thereof. Above EPT
Is a co-assembly consisting of ethylene, α-olefin and a cyclic or acyclic structure having a non-conjugated double bond. More specifically, EPT is a terpolymer composed of ethylene, α-olefin (particularly propylene) and the polyene monomers listed below, and the polyene monomers include dicyclopentadiene, 1,5-cyclooctadiene, and 1-cyclooctadiene. , 1-Cyclooctadiene, 1,6-
Cyclododecadien, 1,7-cyclododecadien,
1,5,9-cyclododecatriene, 1,4-cycloheptadiene, 1,4-cyclohexadiene, norbornadiene, methylenenorbornene, 2-methylpentadiene-1,4,1,5-hexadiene, 1,6-heptadiene , Methyl-tetrahydroindene, 1,4-hexadiene and the like. The copolymerization ratio of each monomer is preferably 30 to 80 mol% of ethylene and 0.1 to 2 of polyene.
It is a terpolymer in which 0 mol% makes the balance α-olefin. More preferably, ethylene is 30 to 60 mol%. Then, the Mooney viscosity ML _{1 + 4} (1
A temperature of 00 ° C. of 20 to 70 is preferable. Specific examples of the EPT include Mitsui EPT402 manufactured by Mitsui Petrochemical Industry Co., Ltd.
1, 4045 and 4070 can be listed. In addition, SBR has a styrene content of 15 to 30 mol%.
A Mooney viscosity ML _{1 + 4} (100 ° C.) of 20 to 80, preferably 35 to 60 is suitable. Specific examples thereof include JSR-1502, JSR-1507, and JSR-1778, manufactured by Japan Synthetic Rubber Co., Ltd. The NBR has an acrylonitrile content of 20 to 60 mol%, preferably 25.
Mooney viscosity ML _{1 + 4} (100 ° C) is 2 at 45 mol%
It is suitable to use one of 0 to 85, preferably 30 to 70. As a specific example, N-23 manufactured by Japan Synthetic Rubber Co., Ltd.
4L, 230S, 230SH can be mentioned.

By mixing the glycol ethers with the unvulcanized rubber, an unvulcanized rubber material is obtained. In this case, the glycol ether is usually blended in an amount of 10 to 60 parts with respect to 100 parts of the unvulcanized rubber. About 15 to 25 parts is preferable. The boiling point of the glycol ethers is preferably about 130 to 250 ° C. That is, the mold molding is usually carried out at 150 to 185 ° C., and if the boiling point of the glycol ether is less than 130 ° C., the evaporation at the time of cleaning is remarkable, and therefore, the phenomenon of deterioration of the cleaning work environment occurs. On the contrary, if the temperature exceeds 250 ° C, it becomes difficult to evaporate and remains in the vulcanized rubber, and the strength of the vulcanized rubber when it is taken out from the mold is weak and the shape may be deformed. The reason is that it becomes difficult to sufficiently remove the oxidation-deteriorated layer of the release agent from the mold surface, and the cleaning workability tends to be deteriorated.

In addition, in the mold cleaning sheet using the unvulcanized rubber material as a base material, an inorganic reinforcing agent (such as silica, alumina, calcium carbonate, aluminum hydroxide, titanium oxide) as a reinforcing agent is added to the unvulcanized rubber ( It is also possible to add a filler). In this case, the amount of the reinforcing agent used is 100% unvulcanized rubber.
It is preferable to set 10 to 50 parts for each part.
Further, as described above, it is possible to add a release agent. Examples of the releasing agent include stearic acid, zinc stearate, carnauba wax, montan wax, stearyl ethylenediamide and the like. It is possible to add 1 to 10 parts of these to 100 parts of unvulcanized rubber.

The other of the two types of the mold cleaning sheet described above uses one or both of imidazoles and imidazolines instead of the above glycol ethers. Other than that, it is exactly the same as the above mold cleaning sheet.

The above-mentioned imidazoles include the following general formula (2) [In the formula (2), R is H or a linear hydrocarbon group having a carbon number of less than 11 with or without a substituent, which may be the same or different from each other. ] Use of an imidazole represented by Typical examples of such imidazoles include 2
-Methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2
-Methylimidazole, etc. and 2,4-diamino-6
[2'-Methylimidazolyl (1) '] ethyl-s-triazine, 2,4-diamino-6 [2'-ethyl-4'
-Methylimidazolyl- (1) '] ethyl-s-triazine and the like.

Further, as the imidazolines, the following general formula (3) [In the formula (3), R is H or a linear hydrocarbon group having less than or equal to 11 carbon atoms, which may or may not have a substituent, and may be the same or different. ] Use of imidazolines represented by Typical examples of such imidazolines include 2
-Methylimidazoline, 2-methyl-4-ethylimidazoline, 2-phenylimidazoline, 1-benzyl-2
-Methylimidazoline, 2-phenyl-4-methyl-5
-Hydroxymethyl imidazoline, 2,4-diamino-
6 [2'methylimidazolyl- (1) '] ethyl-s
-Triazine, 2,4-diamino-6 [2'-methyl-
4'-Ethylimidazolylyl- (1) '] ethyl-s-
Examples include triazine, 1-cyanoethyl-2-methylimidazoline, 1-cyanoethyl-2-methyl-4-ethylimidazoline, etc. Next, of the above two types of mold cleaning sheets, glycol ethers are unvulcanized rubber fabrics. A specific example of what is contained is explained.

[Specific Example A]

After kneading the rubbers shown in Table 1 below with the same raw materials with a kneading roll, a rolling roll was used to form a sheet having a thickness of 7 mm, and a notch having a width of 10 mm and a depth of 5 mm was formed on the surface of the sheet. It was formed parallel to the width direction.

Using the mold cleaning sheet obtained as described above, the mold is cut from the cut portion to have an appropriate size so as to fit several types of transfer molding machines having different mold sizes, and the upper mold is formed as shown in FIG. It was used for cleaning the mold surfaces of 1 and lower mold 2. Reference numeral 10 is a compressed mold cleaning sheet, and 4 is a plunger. The results are shown in Table 1 above,
The product of Example was extremely good as compared with the product of Comparative Example.

[Specific Example B]

Next, a specific example of the above-mentioned two types of mold cleaning sheets in which imidazoles are contained in unvulcanized rubber fabric will be shown. That is, the raw materials shown in Table 2 below were blended in the proportions shown in the same table, kneaded with a kneading roll, and then formed into a sheet having a thickness of 7 mm using a rolling roll, followed by printing to form a 10 mm square cross-cut mark.

Using the mold cleaning sheet obtained as described above, cut into a proper size by cutting with a knife in accordance with the above cross-cut printing marks so as to fit several types of transfer molding machines having different mold dimensions, and the mold surface Used for cleaning. The results are shown in Table 2 above, and the specific example product was extremely good as compared with the comparative example product.

Next, the cleaning sheet around the mold forming portion used for cleaning around the mold forming portion will be described.

This type of sheet is used more frequently than the mold cleaning sheet, and the unvulcanized rubber base material is formed into a layer on one or both of the front and back surfaces of the sheet-shaped fiber base material. The thickness of the mold is 0.2-compared to that for cleaning the mold surface (cavity surface).
It is finished to a very thin thickness of about 1.0 mm.

Examples of the sheet-shaped fiber base material used for this sheet include non-woven fabrics of various materials, for example, organic non-woven fabrics such as polyester non-woven fabrics, inorganic paper non-woven fabrics such as glass paper and glass fiber non-woven fabrics, cellulose mixed glass paper, and paper materials. To be In some cases, a woven fabric or the like may be used instead of the above-mentioned non-woven fabric. As an example of the above-mentioned non-woven fabric, examples of non-woven fabrics made of polyester fiber include Asahi Kasei Co., Ltd., E1030, E1050, E1100, and as sufu kansa made of rayon fiber, Itochu Corporation D-3038, D-3042. can give. As a glass cloth made of glass fiber, Unitika's WK-3025A-104, WL-
110B-28 and KC-0808B-104-AB1.

The unvulcanized rubber material base material formed in layers on one or both of the front and back surfaces of the sheet-like fiber base material has a seam between the upper mold 1 and the lower mold 2 during the cleaning operation shown in FIG. Of the mold is heated and vulcanized to form a vulcanized rubber. At that time, contaminants such as flash adhered around the molding part such as the mold matching part are integrated and the sheet 10 is peeled from the mold. When removing, contaminants such as burrs are peeled off from around the molding part. As such unvulcanized rubber, the same rubber as that used for the mold cleaning sheet is used, and EPT, which is similar to the mold cleaning sheet, is particularly preferable. And, it is the same as the above mold cleaning sheet to mix silica or the like as a reinforcing agent to such unvulcanized rubber.

This clean sheet around the mold forming part is blended with an unvulcanized rubber, if necessary, a reinforcing agent and the like, and kneaded with a kneading roll to form a thin sheet. It can be manufactured by hanging and pressurizing and integrating.

Next, a specific example of the sheet used for cleaning the area around the mold forming portion will be described.

[Specific Example C]

After mixing the raw materials shown in Table 3 below and kneading with a kneading roll, the unvulcanized rubber and the non-woven fabric are formed into a sheet having a thickness of 0.5 mm using a calender roll, and printed by 10 mm.
Marks of the square grid were formed.

The sheet for cleaning around the die molding portion obtained as described above was cut into a proper size by cutting with a knife from a printing mark so as to be suitable for a transfer molding machine having several die sizes. Then, using this, cleaning around the mold forming part was performed. The results are shown in Table 3 above, and it can be seen that the specific example products have excellent performance.

Next, for the mold surface cleaned using the mold cleaning sheet (there is no mold release agent and the molded product adheres to the mold surface and does not release when molded as it is) A release sheet for the purpose of applying a release agent will be described. That is, this release sheet contains a release agent in place of the glycol ethers and imidazoles of the sheet for the purpose of cleaning the mold surface.

Examples of this type of release agent include long-chain fatty acids such as stearic acid and behenic acid, metal salts of long-chain fatty acids represented by zinc stearate and calcium stearate, carnauba wax, montan wax, and montanic acid moieties. Examples include ester waxes represented by saponified esters, long-chain fatty acid amides represented by stearylethylenediamide, and paraffins represented by polyethylene waxes.

This release sheet can be obtained by mixing the release agent and the unvulcanized rubber by a known method, for example, by using a calender roll or the like. It can also be obtained by a method such as production and kneading with a release agent. In these cases, the release agent is usually added in an amount of 1 to 50 parts per 100 parts of the unvulcanized rubber material. Preferred is 3 to 20 parts. The release agent has a melting point of 200 ° C. or less and a boiling point of 2
Those having a temperature of 00 ° C. or higher are preferable. Furthermore, what has a melting point of 50-150 degreeC is preferable. That is, the mold molding is usually performed at 150 to 200 ° C.,
If the melting point of the release agent is higher than 200 ° C., it will not exude to the mold surface, and if the boiling point is lower than 200 ° C., it will evaporate even if it exudes to the mold, so that it tends to lose its function. Because you can see.

It should be noted that other additives such as silica can be similarly blended into the unvulcanized rubber material in the release sheet, as in the case of the mold cleaning sheet.

Next, a specific example of this release sheet will be described.

[Specific Example D]

The raw materials shown in Table 4 below are blended and formed into a sheet having a thickness of 7 mm by using a rolling roll, and a notch having a width of 10 mm and a depth of 5 mm is formed in parallel with the width direction of the sheet and released. I got a sheet for.

The release sheet obtained as described above is folded into appropriate dimensions by folding it from the above marks so as to fit the molds of several types of transfer molding machines having different mold sizes, and using this, the cleaning of the mold surface is completed. Sandwiched between the thermosetting resin molding dies,
After vulcanization at 5 ° C. for 4 minutes, the mold was opened immediately after vulcanization and the molded vulcanized rubber was taken out. After that, a thermosetting resin molding material epoxy resin molding material (manufactured by Nitto Denko Corp., MP-10) is molded by a normal molding method using the mold to which the release agent is applied as described above, and molded. The release state of the product was examined. The results are shown in Table 4 above in comparison with the comparative example (one dummy shot).

As is apparent from Table 4, according to the specific examples, it is possible to impart extremely good releasability.

Next, an example in which the above-mentioned sheet is used and molding is continuously performed will be described.

[Example 1] Using the mold cleaning composition prepared in Example B-3, Nitto Denko's MP-10 was molded in 1000 shots to clean a dirty mold, and then the above-mentioned specific example. A mold release agent was applied to the mold using the mold release sheet prepared in D-3, and molding was performed using the above MP-10. Then, every 50 shots, deburring was performed using the clean sheet around the mold forming portion produced in Concrete Example C-4. In this way, the resin molded product was continuously manufactured.

[Example 2] MP-10 manufactured by Nitto Denko Corporation was molded in 1000 shots,
The mold on which the stain was formed was cleaned using the mold cleaning sheet obtained in Specific Example B-2. Then, after cleaning, the mold release sheet obtained in Example D-2 was used to apply a mold release agent to the cleaned mold, and then the above M was used.
Molding was performed using P-10. In this way, molding was carried out continuously.

[Comparative example]

Nitto Denko MP-10 was molded in 1000 shots,
The dirty mold was cleaned using a melamine resin molding material. Then, MP- used in Comparative Example D-1
10 was subjected to 3 shots and a dummy shot to apply a release agent to the cleaned mold surface. After the dummy shot, continuous molding was performed using the MP-10.

The results obtained in the above Examples and Comparative Examples are shown in the fifth section below.
Shown in the table.

From the results in Table 5, it can be seen that the example products have good mold cleanliness and mold releasability, and excellent results are obtained.

〔The invention's effect〕

As described above, the method for cleaning a mold according to the present invention, when the mold surface is contaminated by the continuous molding operation, forms a mold cleaning sheet using the unvulcanized rubber material as a base material. By sandwiching it between the molds and operating it, contaminants are adsorbed to the unvulcanized rubber fabric, and the unvulcanized rubber fabric in the adsorbed state is vulcanized into rubber by heating at the time of molding. Make it strong so that it can be easily peeled off from the mold surface, then stack the release sheet on the cleaned mold surface and start the molding operation, thereby releasing the mold release agent on the mold surface. At the same time as the application, the unvulcanized rubber material of the release sheet is vulcanized by heating at the time of molding to make it into a strong state and facilitate peeling. Therefore, for cleaning the mold surface and applying the mold release agent, the mold surface can be cleaned and the mold release agent can be applied simply by performing the molding operation once by sandwiching the corresponding sheets, The work can be greatly simplified. Moreover, in that case, a good working environment can be maintained without generating a formalin odor or an amine odor as in the case of mold cleaning using a conventional melamine resin molding material.

[Brief description of drawings]

FIG. 1 is a perspective view of a mold cleaning sheet used in the present invention,
FIG. 2 is an explanatory view of the cut portion, FIG. 3 is an explanatory view of a modified example of the cut portion, FIGS. 4 and 5 are explanatory views of formation of the cut portion, and FIG. 6 is an embodiment of the present invention. FIG. 7 is an operation explanatory view of another embodiment, and FIGS. 8 and 9 are explanatory views of a conventional example. 10 ... Sheet 11 ... Mark

Claims (4)

[Claims] 1. A step of sandwiching a mold cleaning sheet using an unvulcanized rubber material as a base material between a pair of molding dies, and in that state, a pair of molding dies is molded and operated to clean the mold surface. The step of removing the mold cleaning sheet from between the pair of molding dies after the molding operation, and the unvulcanized rubber material as the base material between the pair of molding dies whose mold surfaces have been cleaned. And a step of sandwiching a release sheet containing a release agent, and a step of forming a pair of molding dies in that state to apply a release agent to the die surface, Mold cleaning method. 2. The method of cleaning a molding die according to claim 1, wherein the unvulcanized rubber material used for the sheet for cleaning a die comprises an unvulcanized rubber and a removal aid. 3. The removal aid is at least one compound selected from the group consisting of glycol ethers, imidazoles and imidazolines (1) or (2).
The method for cleaning a molding die described. 4. The mold cleaning sheet is one in which marks for cutting the sheet into appropriate sizes are provided at predetermined intervals on the sheet surface, and the mold cleaning sheet is cut into appropriate sizes using the marks. The method for cleaning a molding die according to any one of items (1) to (3).