JP2002036252A - Mold cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the control of a mold by instantaneously removing the substance adhering to and left on the surface of the mold for molding a synthetic resin, rubber or the like. SOLUTION: A projection material with a particle size of 100-3,000 μm, which is obtained by compounding at least either one of an inorganic filler, an organic filler and an antistatic material with a urea resin, is blown against the surface of the mold along with an air stream to instantaneously remove the residual substance bonded to the surface of the mold to clean the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a mold in which mold management such as synthetic resin and rubber is easily removed by instantaneously removing substances remaining on the mold surface.

[0002]

2. Description of the Related Art During molding of rubber or urethane, a molding material that slightly remains and adheres to a mold surface is cleaned every several shots or at a predetermined frequency to maintain the molding accuracy. There is a need. In cleaning the mold, in addition to alkali cleaning, cleaning by a blast method using a glass blast material, corn powder, or the like is performed. In addition, air and fine solid particles (walnut powder) sufficiently lower than the mold temperature are sprayed onto the cavity surface of the molded mold and adhered to the molding surface as a method for cleaning the resin molding mold by the blast method. For removing the residual resin (JP-A-55-82606)
No.) or a particle size of 2 against the alkali-cleaned rubber mold.
A method is also known in which a melamine resin powder having a 0 to 120 mesh and a Mohs hardness of 3 to 4 is sprayed together with an airflow to remove adhered substances from the mold surface (Japanese Patent Publication No. 6-24730).

[0003]

The alkali cleaning is suitable for cleaning a precise and complicated mold, but requires a long time for cleaning, and it is difficult to treat a waste liquid. In the blasting process using a glass blasting material, the mold is greatly worn and the mold is apt to sag. Further, in the blast treatment using corn or walnut powder, it is not easy to remove the deposits because it takes time for cleaning. Furthermore, when the object (resin molding or rubber molding die) is sprayed using a crushed melamine resin molded product,
The surface of the workpiece is ground by the impact of the blasting of the blasting material, and the effect of removing deposits is exhibited by the hammer effect of repeated impact.However, the hammer effect of the blasting material with melamine resin hardness damages the target substrate. Is generated. Accordingly, an object of the present invention is to provide a method of cleaning a synthetic resin / rubber molding die by spraying a blast material obtained by blending various fillers with urea resin.

[0004]

Means for Solving the Problems To achieve the above object, the present invention relates to a particle size obtained by mixing at least one of an inorganic filler, an organic filler and an antistatic material with a urea resin. The method is characterized in that a blast material of 100 to 3000 μm is sprayed on the surface of the mold together with the gas flow to remove the adhesion on the surface of the mold and residual substances. The inorganic filler is one or more of alumina, silica, carbon black, calcium carbonate, magnesium carbonate, talc, clay, glass fiber and glass balloon. The inorganic filler is a conductive fiber, powder, or fine powder made of a metal, and iron oxide is particularly preferable. Further, the organic filler is one or more of cellulose, a cellulose derivative, α-cellulose and wood flour, and the antistatic material is one or more of an anionic, cationic or nonionic surfactant or Two or more.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the spraying of a thermosetting resin blasting material exerts an effect of removing deposits by a hammer effect that repeatedly impacts a work mold surface , but the melamine resin blasting material is used. The hammer action causes problems such as damaging the target substrate and causing a crash of the shot material itself. In view of the above, the present invention has repeatedly performed experiments using a blasting material obtained by pulverizing a urea resin molded body instead of a melamine resin. As a result, the target material was not damaged (buffering effect) and the blasting material itself was prevented from crashing during blasting. Alternatively, it has been found that the number of times the shot material can be recycled can be further increased.

In the present invention, a crushed piece or powder of a urea resin molded product is used as a projection material for cleaning a mold. This material is non-polluting during blasting, has high electrical insulation resistance, is resistant to alkalis and acids, and has no danger of burning (flammability, ignitability) or toxicity (styrene, ester, etc.).
By blending various compounding materials, antistatic properties, suitable strength,
Hardness, specific gravity, toughness and recyclability can be realized.

[0007] The projectile in the present invention is as follows:
Excellent antistatic properties, mold cleaning properties, and excellent recyclability. 1. The antistatic property is to crush the resin plate-like molded product and then pulverize it to a predetermined particle size. In the production process of the raw material for molding, usually, the main filler (pulp) is used to increase mechanical strength. , Cellulose fiber: about 40% of the resin material) is mixed with a small amount of glass fiber cloth pieces. In the present invention,
Separately from this, a specific filler is blended in a colorant mixing stage using a ball mill after aging and drying of the resin.

As the specific filler, metal fibers, metal particles or metal fine pieces are used, and among them, spherical, crushed, or fibrous iron oxide (particle size: 0.1 μm or less) is blended by 10% or less. It is preferable to add a small amount of an organic fiber (polypropylene, acrylic fiber, or the like) having a length of 0.5 to 0.01 μm for adjusting mechanical strength.

By blending a highly conductive material such as metal fibers and metal fine pieces, the generation of static electricity during pulverization, projection and collection is prevented. Static electricity is about 1 / 10,000,000 in one side in air
It is known whether or not there is one electron in the square of m. However, if a very small amount of conductive fine pieces is blended, a sufficient discharge can be performed. Earth resistance in general commercial electricity 1
It is said that 00Ω is equivalent to 1,000,000Ω in static electricity, and the effect of ground discharge is sufficient. In addition, by mixing suitable amounts of metal fibers, metal fines, and adjustable specific gravity shot material, to improve the mold cleaning due to blasting.

[0010] 2. Mold cleaning properties By mixing one or more of the above fillers with the urea resin, a shot material having appropriate strength and hardness and excellent toughness can be obtained, and there is no possibility of damaging the die surface during blasting.

3. Recyclability The blasting material is obtained by pulverizing a resin molded product and has an irregular fine polyhedron with sharp ridges. By spraying on the object during the blasting operation, the blast material is crushed and the particle size is further reduced, and the sharp ridge portion is somewhat rounded, but this is sieved for each predetermined particle size and reused . Even if the particle size of the blast material is reduced by blasting, the shape and cleaning efficiency of each particle hardly change. The blasting material used for the removal of the deposits on the mold is separated and recovered by using a separation device such as a cyclone to remove the separated pieces and dust, and then reused. The degree of hardness of the target product, the hardness of the shot material,
Depending on specific gravity, air pressure, spray angle, spray distance, etc., it can be reused several times to several tens of times.

Together with the above-mentioned specific filler, an antistatic property,
In order to provide hardness, specific gravity and toughness in addition to strength, inorganic fillers and organic fillers (size 0.01 to 500 μm, addition amount 0.01
~ 50%). One or more inorganic fillers and organic fillers, and one or more surfactants, thermoplastic resins or rubbers are blended.

As the inorganic filler, alumina, silica,
One or more of carbon black, calcium carbonate, magnesium carbonate, talc, clay, glass fiber and glass balloon are blended in an amount of 0.1 to 15% by weight based on the composite resin. As the organic filler, 3 to 20% by weight of one or more of cellulose, cellulose derivative, α-cellulose and wood flour is blended.

Examples of the surfactant include anionic compounds such as alkylsulfonate, alkylbenzenesulfonate and alkylphosphate, cationic compounds such as quaternary ammonium chloride, quaternary ammonium nitrate and quaternary ammonium sulfate, and poly (oxy) alkyl. One or more nonionics such as amines, poly (oxy) alkyl ethers, glycerin fatty acid esters, and sorbitan fatty acid esters, and 0.001 to 5% by weight.
Mix.

As the thermoplastic resin, AAS, AES,
One or more of AS, ABS, MBS, EVA, butadiene resin, vinyl acetate resin, PEO, PPO, acrylic resin, methacrylic resin, styrene resin and polyacrylonitrile resin are blended in an amount of 0.01 to 10 parts by weight. For rubber, SBR, BR, IR, EPM, EPDM, NB
R, IIR, urethane rubber and silicone rubber are suitable, and are blended in an amount of 0.01 to 2.0% by weight.

In order to produce the shot material of the present invention, for example, as disclosed in International Application No. PCT / JP00 / 00516, a plate-shaped molded article of urea resin is about 2 to 4 mm.
A crusher section for crushing into irregular shaped dice or pellets having a corner (a flat object having a maximum thickness of 5 mm and a side of about 7 mm), and a sorting section for removing metal and foreign matter in the crushed material crushed by the crusher section. A crushing unit equipped with crushing rolls, which have undulations with a phase shift of 1/2 pitch formed on the pair of roll surfaces and crush the crushed material selected by the sorting unit, as well as the crushing rolls of the crushing unit Equipped with a multi-stage crushing roll pair that forms irregularities with a phase shift of 1/2 pitch on the roll surface and processes the crushed material obtained at the crushing part into an irregular fine polyhedral projection material with sharp ridges This is obtained by a manufacturing apparatus including a pulverizing unit and a classifier arranged downstream of the pulverizing unit.

In order to manufacture a shot material, as described above, a urea resin plate (thickness 3 to 5 mm, length 300 × width 500)
mm), and crushing (roughly dividing) the resin molded plate into an irregular die or pellet of approximately 2 to 4 mm square (a flat object having a maximum thickness of 5 mm × 7 mm on a side) in a crusher portion. And then pulverized by the multi-stage pulverizing roll as described above. The crushing of the above resin plate is different from crushing by a hammer mill, disk crusher, cone crusher, oscillator, etc. A type that crushes with a fixed blade is used. Hammer crushers and the like are not effective because only a large number of cracks appear in the pulverized product or dust is generated during pulverization.

A description will now be given of the reuse of the shot material during the blast operation. In order to clean by spraying the shot material, the synthetic resin molding or rubber mold mold part is covered with a hood and the shot material is sprayed from a nozzle, but the spray material after spraying and dirt separated from the mold surface are sprayed. Is collected. As described above, the blast material is crushed by the spraying on the target object, the particle diameter becomes small, and the sharp ridge portion is rounded, but this is sieved using a separation device such as a cyclone and the blast material is sieved. Is reused repeatedly.

The shot material preferably has a specific gravity of 1.3 to 1.7 and a Rockwell hardness of 100 to 130. Particle size is 100
Those having a wide particle size distribution in the range of from 3,000 μm to 150 μm are preferably used. In other words, the mold has a mixture of a relatively flat part and a part having a complicated shape.However, the cleaning efficiency of the relatively flat part is better if the particle size is large as long as the mold surface is not damaged. On the other hand, when cleaning a portion having a complicated shape, a shot material having a fine particle size can easily reach the details of a mold, and therefore, a wider particle size distribution is advantageous as described above. Also, when spraying,
It is preferable to perform blasting at a nozzle diameter of 6 to 10 mm, an air pressure of 0.2 to 0.5 MPa, and a spray angle of 300 to 40 degrees.

The performance of the above-mentioned blasting material is specified in terms of material, hardness and specific gravity, and is excellent in cutting performance, abrasion resistance, heat resistance and antistatic property, high speed in blasting operation and low dust generation rate. The projectile dust itself is non-polluting and can be treated as general waste.

[0021] Example 1 Urea 100 parts, 200 parts by weight of formaldehyde were mixed, heated and adjusted to pH 9-10, to give a reacted at place flow down urea resins. After drying, 5 parts by weight of alumina and a curing agent were added, and the mixture was cured by heating, pulverized and classified to obtain a resin projection material of 100 to 3000 μm.

[0022] Example 2 Urea 100 parts, 200 parts by weight of formaldehyde were mixed, heated and adjusted to pH 9-10, to give a reacted at place flow down urea resins. After drying, 30 parts by weight of α-cellulose and a curing agent were added, and the mixture was cured by heating, pulverized and classified to obtain a resin shot material of 100 to 3000 μm.

Example 3 100 parts by weight of urea and 200 parts by weight of formaldehyde were mixed, adjusted to pH 9 to 10, heated, and reacted under reflux to obtain a urea resin. After drying, 1 part by weight of polyoxyethylene noniether and a curing agent were added, and the mixture was cured by heating, pulverized and classified to obtain 10 parts.
A resin blast material of 0 to 3000 μm was obtained.

COMPARATIVE EXAMPLE 100 parts by weight of urea and 200 parts by weight of formaldehyde were mixed, adjusted to pH 9 to 10, heated, and reacted under reflux to obtain a urea resin. After drying, a curing agent was added and the mixture was cured by heating, pulverized and classified to obtain a resin shot material of 100 to 3000 μm.

The blasting materials obtained in Examples 1 to 3 and Comparative Example were applied at an air pressure of 0.2 MPa and a blasting material injection amount of 0.9 kg / mi.
n, the rubber tire mold mold cavity surface by spraying angle 30 to 40 degrees, to remove deposits cavity surface was blasted with 3 minutes 1 m ² per removal time. As a result, the shot materials obtained in Examples 1 to 3 have improved recyclability and are profitable. Moreover, it was hard to be broken, the mold surface was not damaged, and no static electricity was generated.

Particularly, in Example 1, a remarkable effect on the peeling force was observed by blending the inorganic filler (alumina). In Example 2, by adding an organic filler (α-cellulose), toughness was improved, cracking was difficult, and an effective effect on recyclability was obtained. In Example 3, the addition of a surfactant (polyoxyethylene noniether) provided a remarkable effect on antistatic properties. On the other hand, in the shot material obtained in the comparative example, the abrasive was inferior to the shot materials of Examples 1 to 3, and the shot material was cracked. Further, the amounts of the projection material and the fine powder were considerably larger than those in Examples 1 to 3, and generation of static electricity was observed.

[0027]

As described above, the present invention provides a urea resin having a particle size of 200 to 300 obtained by blending at least one of an inorganic filler, an organic filler and an antistatic material.
A 0 μm blast material is sprayed together with the gas flow on the surface of the mold and with the gas flow on the surface of the rubber mold, so that the adhesion of the mold surface and the residue can be instantaneously removed. it can. Removal of extraneous matter and the like without damaging the mold surface by spraying urea resin with a blasting material makes mold maintenance easier.

Claims (6)

[Claims] 1. A blasting material having a particle size of 100 to 3000 μm obtained by blending at least one of an inorganic filler, an organic filler, and an antistatic material with a urea resin is applied to a surface of a mold by gas flow. A method for cleaning a mold, characterized in that the mold is sprayed together with the mold to remove the adhesion of the mold surface and residual substances. 2. The method according to claim 1, wherein the inorganic filler is at least one of alumina, silica, carbon black, calcium carbonate, magnesium carbonate, talc, clay, glass fiber and glass balloon. . 3. The method according to claim 1, wherein the inorganic filler is a conductive fiber, powder, or fine powder made of a metal.
The method for cleaning the described mold. 4. The method according to claim 3, wherein the inorganic filler is iron oxide. 5. The method according to claim 1, wherein the organic filler is one or more of cellulose, a cellulose derivative, α-cellulose and wood flour. 6. The method for cleaning a mold according to claim 1, wherein the antistatic material is one or more of an anionic, cationic or nonionic surfactant.