JPH05269755A - Cleaning agent for plastic molding machine - Google Patents

Abstract

PURPOSE:To obtain a cleaning agent for efficiently removing a thermoplastic resin remaining in a molding machine (extrusion or injection type) and an additive, such as a dye or pigment, contained in said resin upon completion of operation in the plastics molding machine. CONSTITUTION:A plastics molding machine cleaning agent is prepared by incorporating 100 pts.wt. thermoplastic resin having an MI value of 0.01-5, 5-30 pts.wt. inorganic porous substance having an average particle diameter of 1-30mum, and l-20 pts.wt. lubricant. Especially, when a diatom earth is used as the inorganic porous substance, a superior cleaning effect is exhibited.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention efficiently removes the thermoplastic resin remaining in the molding machine (extrusion / injection) and the additives such as dyes and pigments contained therein at the end of the work on the molding machine for plastics. The present invention relates to a cleaning agent.

[0002]

2. Description of the Related Art In the process of molding a thermoplastic resin, when a product type is changed, cleaning is generally performed with a resin used for the next molding process in order to eliminate the influence of the preceding product type. However, a large amount of resin is required for cleaning the molding machine by this method, but it is not possible to completely remove stains inside the molding machine with a complicated structure, and it mixes with the succeeding product and coloring, transparency and physical properties. Often occurs. Therefore, the following compounds have been developed and sold as cleaning resin compositions for solving such drawbacks and cleaning the molding machine in a shorter time. A) A thermoplastic resin blended with a lubricant such as higher fatty acid or higher fatty acid amide. B) Thermoplastic resin containing calcium carbonate, calcium silicate,
A mixture of a large amount of inorganic substances with high hardness such as silica sand and glass fibers. C) A method of using a semi-molten acrylic resin.

However, in A), even if used in a large amount, the cleaning effect is insufficient, which is not preferable. In B), a so-called general-purpose resin having a low molding temperature (250 ° C. or lower), for example, a resin composition containing polystyrene, polyethylene, polypropylene or the like is used, but some effect can be obtained, but A large amount of cleaning agent is required to completely clean the molding machine. In C), not only a large load is applied to the molding machine at the time of cleaning, but also a bad odor is easily generated, and the cleaning agent itself easily remains in the cylinder of the molding machine. In particular, various engineering plastics such as polyamide, polycarbonate, and modified polyphenylene oxide resin, which have been actively developed in recent years, are molding materials that have a high molding processing temperature and easily remain in the molding machine. Therefore, for cleaning the inside of the molding machine after using these resins, the cleaning effects are hardly exhibited by the above methods A), B) and C).

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks, and by using a small amount of a cleaning resin composition, the resin composition of the preceding type remaining in the molding machine is completely removed. It is to provide a cleaning agent for a molding machine that can be used. Moreover, we considered the development of a cleaning agent that is suitable not only for general-purpose resins but also for cleaning inside molding machines after using engineering plastics with high molding temperatures.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems that have not been solved in the past, and it is used as a cleaning agent for the residue in a plastic molding machine. It has been found that the one in which the functional substance is mixed with the thermoplastic resin has a high cleaning action and can significantly reduce the cleaning time and the cleaning resin. That is, the present invention is based on MI
100 parts by weight of thermoplastic resin with a value of 0.01 to 5, average particle size of 1 to 30 μ
Is a detergent for a plastic molding machine, which comprises 5 to 30 parts by weight of the inorganic porous material and 1 to 20 parts by weight of a lubricant.

The thermoplastic resin used in the present invention includes:
Use the one with MI value of 0.01 to 5 g / 10 min (200 ° C, 5 kg load). If the MI value is less than 0.01, it is difficult to melt under standard conditions (200 to 300 ° C.) and it cannot be used as a cleaning agent. On the other hand, if the MI value is larger than 5, the melt viscosity becomes small and a sufficient cleaning effect cannot be expected. When the MI value is within the above range of 0.01 to 5 g / 10 minutes, general thermoplastic resins used for injection molding, extrusion molding and the like can be widely used as detergents. Specific examples include polyethylene, polypropylene, polystyrene, AS resin, ABS resin, polybutene resin, polymethylmethacrylate resin and the like. These resins may be used alone or in combination of two or more.

Examples of the inorganic porous material used in the present invention include diatomaceous earth, zeolite, activated carbon and the like. These inorganic porous materials possess the following characteristics. a. The apparent specific gravity difference from the thermoplastic resin is small, and the inorganic porous material does not settle and separate from the thermoplastic resin even when it is mixed with the resin during the production of the detergent, and therefore, it is easily and uniformly kneaded. b. It is porous, has a large surface area, and excels in polishing even with a small amount. c. Even when using a resin that is difficult to knead a lubricant,
The lubricant can be adsorbed at a high concentration. d. It is excellent in terms of high hardness. The average particle size of these inorganic porous materials is 1 to 30 μm. If the average particle size is smaller than 1 μm, it becomes difficult to disperse the particles uniformly in the resin, and the cleaning effect becomes small, which is not preferable. Further, as the particle size increases, the surface area decreases and the cleaning effect decreases, so it is preferable to use a particle size of 1 to 30 μm. In particular, diatomaceous earth is excellent in the properties of a, b, c and d described above, and therefore exhibits an excellent effect as a detergent for a plastic molding machine. The lubricant used in the present invention can be selected from commonly used internal lubricants and external lubricants, for example, higher fatty acid amide, higher alcohol, glycerin ester, higher fatty acid, polyethylene wax, liquid paraffin, paraffin wax, bisamide, Examples thereof include higher fatty acid metal salts.

In the present invention, 5 to 30 parts by weight of the inorganic porous material and 1 to 20 parts by weight of the lubricant (hereinafter abbreviated as "part") are blended with 100 parts by weight of the thermoplastic resin. If the compounding amount of the inorganic porous material is less than 5 parts, the effect of peeling off the resin composition adhering to the cylinder wall surface or the screw surface becomes insufficient, and the cleaning effect decreases, which is not preferable. When it is more than 30 parts, the cylinder wall of the molding machine and the screw surface are greatly worn, which is not preferable. If the blending amount of the lubricant is less than 1 part, it is not preferable because the action of the lubricant to penetrate the resin and the colorant adhering to the cylinder wall surface and the screw surface is insufficient. Also, if the lubricant is more than 20 parts, it is difficult to granulate during the production of the detergent, and further, the lubricating effect of the obtained detergent is too high, and therefore the cleaning effect is lowered, which is not preferable. .. Incidentally, the cleaning agent for a plastic molding machine of the present invention,
If desired, stabilizers, antioxidants and the like may be optionally mixed. Further, the detergent for a plastic molding machine of the present invention may be produced by a usual method, for example, a tumbler mixer or a high-speed mixer may be mixed and an extruder may be used for kneading. The shape thereof may be any of powder, pellet, flake and the like.

[0009]

EXAMPLES Examples and comparative examples will be described below. Example 1 100 parts of high-density polyethylene having an MI value of 0.5 and diatomaceous earth having an average particle size of 15 μ (manufactured by Showa Kagaku Kogyo: Radiolite 600) 20
Parts, 3 parts of ethylene bis-stearic acid amide and 2 parts of zinc stearate as a lubricant, and 0.2 parts of an antioxidant BHT as an optional component, and after mixing the above 4 components with a tumbler,
It is molded into pellets with an extruder to obtain the detergent for a plastic molding machine of the present invention. When 5 kg of a polyethylene resin composition containing 2% of carbon black was extruded with an extruder having a diameter of 50 mm and then washed with 2 kg of the above-mentioned detergent for plastic molding machines, coloring by carbon black was completely removed. After that, 0.5 kg of natural resin could easily remove the above-mentioned detergent used for this washing from the molding machine.

Example 2 100 parts of polystyrene resin having an MI value of 1.0, 25 parts of diatomaceous earth having an average particle size of 14 μ (manufactured by Showa Kagaku Kogyo: Radiolite 500),
Using 5 parts of polyethylene wax and 5 parts of zinc stearate as a lubricant, a detergent for a plastic molding machine of the present invention was obtained in the same manner as in Example 1. Using an injection molding machine with a mold clamping pressure of 150 tons, 2 kg of flame-retardant ABS resin with a cylinder temperature of 180
Molded at ° C. After continuously washing with 0.5 kg of the above detergent, the cylinder temperature was raised to 250 ° C. for molding using the heat resistant ABS resin. Molding of the heat-resistant ABS resin was started after the temperature was raised, but non-defective products were obtained after the 5-shot trial molding, and there were no defective products in which foreign substances were mixed even after that. Example 3 Instead of the diatomaceous earth used in Example 1, a synthetic zeolite having an average particle size of 3 μ (manufactured by Mizusawa Chemical Industry Co., Ltd .: Shilton CP)
T-30) Same composition as in Example 1 except that 30 parts are used. Thereafter, the same operation as in Example 1 is performed.

Comparative Example 1 When the same test as in Example 1 was carried out by washing with a high-density polyethylene natural pellet instead of the detergent for a plastic molding machine of the present invention, black was not completely removed even when extruded by 10 kg. .. Comparative Example 2 500 g of a commercially available detergent pellet having a composition of 100 parts of polyethylene resin, 60 parts of calcium carbonate and 8 parts of a surfactant was used for washing in the same manner as in Example 2. When the natural resin was molded after washing, black-spot foreign matters sometimes entered the molded product, and a defective rate of about 10% occurred.

Comparative Example 3 Example 1 except that the diatomaceous earth used in Example 1 was 3 parts.
It is a detergent with the same composition as. Example 1 using the cleaning agent
As a result of carrying out the same washing test as above, the coloring due to carbon black was finally removed by using 8 kg of the detergent.
To remove this cleaning agent, 1.5 kg of natural resin was required. Comparative Example 4 Example 1 except that the diatomaceous earth used in Example 1 was 40 parts.
It is a detergent with the same composition as. The carbon black pigmentation was finally removed using 3 kg of the detergent. To remove this cleaning agent, 1.5 kg of natural resin could be removed from the molding machine.

Comparative Example 5 A detergent having the same composition as in Example 1 except that the zeolite used in Example 3 has an average particle size of 40 μm. Comparative Example 6 A detergent having the same composition as in Example 1 except that the high density polyethylene used in Example 1 has an MI value of 7. that's all,
An extruder (diameter 50 mm) and an injection molding machine after molding using a thermoplastic resin are prepared by using the cleaning agent for a plastic molding machine of the present invention obtained in Examples 1 to 3 and the cleaning agent obtained in Comparative Examples 1 to 6. Measure the cleaning effect of (clamping pressure 150 ton) and display the result.

[Table 1] Shown in. The cleaning effect was determined by measuring the amount of the cleaning agent used and the cleaning time, the amount of the natural resin (replacement agent) used to remove the used cleaning agent, and the replacement time, and then judging the total. The criteria are determined under the following conditions. ⊙ ················································································································· You can use a small amount of replacement agent. Δ: A large amount of cleaning agent is required to obtain a satisfactory cleaning effect. X: No cleaning effect is exhibited even if a large amount of cleaning agent is used.

[0014]

The cleaning agent for a plastic molding machine of the present invention has a great feature in that it contains an inorganic porous material. Since the inorganic porous material has a small apparent specific gravity and is close to the specific gravity of the thermoplastic resin, the inorganic porous material does not sediment and separate even when mixed with the resin, and thus a uniformly dispersed detergent can be obtained even when kneading. The plastic molding machine cleaning agent of the present invention, when used, the lubricant is first melted, which penetrates into the resin adhering to the cylinder wall surface and the screw surface, the colorant, etc., swells, and facilitates peeling. There is. After that, the characteristics of the inorganic porous material are skillfully utilized to exert the cleaning effect. That is, the inorganic porous material has a large surface area, and even if it is mixed in a small amount, it exhibits an excellent polishing effect. Further, the lubricant can be adsorbed at a high concentration even when it is based on a resin that is difficult to knead the lubricant because it is porous. In particular, diatomaceous earth, which is an inorganic substance and has a high hardness, can efficiently remove the residual resin composition in the molding machine.

Therefore, the cleaning agent for a plastic molding machine of the present invention exhibits an excellent cleaning effect with a small amount of use, as compared with a conventional cleaning agent containing an inorganic substance containing calcium carbonate, calcium silicate or glass fiber. These effects are not only for polyethylene, polypropylene, ABS resin, polystyrene general-purpose resin compositions, but also for molding plastic molding products such as polyamide resin, polycarbonate resin, modified polyphenylene oxide resin, etc. The machine can be easily washed. As described above, by using the cleaning agent for a plastic molding machine of the present invention, it is possible to easily change the color and the resin used, so that the cost and time required for cleaning can be greatly saved.

Claims (2)

[Claims] 1. A plastic comprising 100 parts by weight of a thermoplastic resin having an MI value of 0.01 to 5, 5 to 30 parts by weight of an inorganic porous material having an average particle size of 1 to 30 μ, and 1 to 20 parts by weight of a lubricant. Cleaning agent for molding machines. 2. The inorganic porous material is diatomaceous earth.
The cleaning agent for a plastic molding machine described.