JP2020111726A - Cleaning composition for resin molding machinery - Google Patents

Abstract

To provide a cleaning composition for resin molding machinery having improved balance between cleaning performance and ease of replacement with a molding material after cleaning.SOLUTION: A cleaning composition for resin molding machinery contains at least two polyethylene resins, and a difference between the maximum melting point and the minimum melting point of the polyethylene resin is 15°C or higher.SELECTED DRAWING: None

Description

The present invention relates to a detergent composition for a resin molding machine containing a polyethylene resin.

Generally, resin molding processing machines such as an extrusion molding machine and an injection molding machine are used for operations such as coloring, mixing and molding of resins. In addition to additives such as dyes and pigments contained in or molding materials, deterioration products (pyrolysis products, scorched charcoal, etc.) generated from resins and the like may remain in the molding machine. If this residue is left unattended, the residue may be mixed into the molded product during the subsequent resin molding process, which may cause a defective product appearance. In particular, when a transparent resin is molded, even if minute carbides or the like are easily visible, the appearance of the molded product becomes poor, which causes a problem of increasing the defective product occurrence rate. Therefore, it is desired to completely remove the residue from the molding machine.

Conventionally, in order to remove residues from the molding processing machine, (1) a method of manually disassembling and cleaning the molding processing machine, (2) a molding material used for the next molding without stopping the molding processing machine. A method of filling the molding machine and gradually discharging the residue by this, (3) a method of using a cleaning agent, and the like are adopted.

The above method (1) is not efficient because it is necessary to stop the molding processing machine, and has a problem that the molding processing machine is easily damaged because it is physically removed manually. The above method (2) often requires a large amount of molding material in order to remove the residue, takes a long time to complete the work, and has a problem that a large amount of waste is generated. .. Therefore, in recent years, the method (3) using the cleaning agent has been favorably used because of its excellent cleaning power for removing the residue in the molding machine.

JP-A-59-124999 JP-A-60-139411

After cleaning with the cleaning agent, before the next molding is started, the cleaning agent remaining in the resin molding machine is usually replaced by the next molding material. Therefore, the cleaning agent is required to have a high detergency for the molding material used in the previous molding and an easily replaceable property by the molding material used in the next molding.

As an example of the cleaning agent, Patent Document 1 describes a cleaning agent in which an inorganic filler is uniformly kneaded into a resin. Patent Document 2 describes a detergent composed of linear low-density polyethylene, calcium carbonate, sodium alkylbenzene sulfonate, sodium stearate, zinc stearate, and the like.
However, the cleaning agents described in Patent Documents 1 and 2 have a problem in that the ease of substitution is low as compared with the cleaning performance.

Therefore, an object of the present invention is to provide a detergent composition for a resin molding processing machine, in which the balance between the cleaning performance and the easy substitution by the molding material after cleaning is improved.

As a result of intensive studies to solve the above problems, the present inventors have found that a detergent composition containing two or more types of polyethylene-based resins having a large difference in melting point as a thermoplastic resin serving as a base material has good cleaning performance and easy cleaning performance. They have found that a good balance with the substitutability is achieved, and have completed the present invention.
That is, the present invention is as follows.

(1)
A detergent composition for a resin molding machine, comprising at least two types of polyethylene-based resin, wherein the difference between the maximum melting point and the minimum melting point of the polyethylene-based resin is 15°C or more.

(2)
The cleaning composition for a resin molding machine according to (1), which contains 1 to 20% by mass of a polyolefin resin that does not substantially flow at a temperature exceeding the melting point of the resin, relative to 100% by mass of the cleaning composition. ..

(3)
The cleaning composition for a resin molding machine according to (2), wherein the polyolefin resin is an ultra-high molecular weight polyolefin.

(4)
The cleaning composition for a resin molding machine according to any one of (1) to (3), which contains 1 to 20% by mass of a filler with respect to 100% by mass of the cleaning composition.

(5)
The resin molding machine cleaning according to (4), wherein the filler is at least one selected from calcium carbonate, talc, mica, wollastonite, glass fiber, glass beads, silica, alumina, and barium sulfate. Agent composition.

(6)
A method for cleaning a resin processing machine using the detergent composition for a resin molding processing machine according to any one of (1) to (5).

The detergent composition of the present invention has the effect of improving the balance between the washing performance and the ease of substitution with the molding material after washing.

Hereinafter, modes for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the present embodiment described below, and can be implemented with various modifications within the scope of the gist thereof.

The detergent composition for a resin molding processing machine of the present embodiment (which may be simply referred to as “detergent composition” in the present specification) contains at least two kinds of polyethylene-based resin, The difference between the maximum melting point and the minimum melting point is 15°C or more. Further, it may contain a specific amount of a polyolefin resin or a filler that does not substantially flow at a temperature exceeding the melting point of the resin.

The details will be described below.
[1] Detergent composition <Polyethylene resin>
As the thermoplastic resin, polyethylene resins used in general injection molding and extrusion molding can be widely used. The polyethylene resin contains at least two kinds of polyethylene resins having different melting points, and the melting points are different. It is necessary that at least two kinds of polyethylene resins include at least a combination of polyethylene resins having a difference between the maximum melting point and the minimum melting point of 15° C. or more.
In the present specification, the melting point can be determined by a differential scanning calorimetry (DSC) according to JIS K7121.
When measuring the melting point by DSC, a small piece of 5 mg of the sample resin is prepared in advance, the weight is precisely weighed and placed in an aluminum pan, and the lid is sealed. An aluminum pan filled with a sample resin is placed on the sample stand of the DSC measuring device, and the temperature is raised from 20° C. to 200° C. at a rate of 20° C./min as the first temperature rise, and is held for 2 minutes after reaching 200° C. Next, the temperature is lowered from 200° C. to 20° C. at a rate of 20° C./minute, and after reaching 20° C., the temperature is held for 2 minutes, and then the temperature is raised from 20° C. to 200° C. at a rate of 20° C./minute as the second heating. The temperature of the peak of the DSC curve obtained during the second heating above is taken as the melting point of the sample resin.

The difference between the maximum and minimum melting points of the two or more polyethylene-based resins contained in the detergent composition must be 15° C. or more. If it is less than 15° C., the residual property is poor and the following molding is performed. The ease of substitution with the material is reduced. In particular, the temperature is preferably 20° C. or higher from the viewpoint of excellent cleaning performance and easy substitution.
Further, the difference between the maximum and minimum melting points of two or more polyethylene-based resins contained in the above-mentioned detergent composition is that the polyethylene resin having the minimum melting point has a remarkably low melting point in order to solidify the purging waste during cleaning. Since it takes a long time and the workability is impaired, the temperature is preferably 30° C. or lower, and more preferably 25° C. or lower.

The melting point of the polyethylene-based resin having the maximum melting point is preferably 125° C. or higher, more preferably 130° C. or higher, from the viewpoint of further excellent cleaning performance and easy substitution.
The melting point of the polyethylene-based resin having the minimum melting point is preferably 120° C. or lower, more preferably 115° C. or lower, from the viewpoint of further excellent cleaning performance and easy substitution.

When the mass ratio of the polyethylene-based resin having the maximum melting point and the polyethylene-based resin having the minimum melting point contained in the detergent composition is in the range of 10:90 to 90:10, the above effect is remarkably achieved. Is more preferable, and more preferably 30:70 to 70:30.

The mass ratio of the polyethylene resin having the highest melting point contained in the cleaning composition is 5 to 100% by mass of the cleaning composition from the viewpoint of further excellent cleaning performance and easy substitution. It is preferably 90% by mass, more preferably 15 to 70% by mass.
Further, the mass ratio of the polyethylene resin having the lowest melting point contained in the detergent composition is 100% by mass of the detergent composition, from the viewpoint of having more excellent cleaning performance and easy substitution. It is preferably 5 to 90% by mass, and more preferably 15 to 70% by mass.
Further, the total mass ratio of the polyethylene resin having the highest melting point and the polyethylene resin having the lowest melting point contained in the detergent composition is more excellent in cleaning performance and easily replaceable. It is preferably 50 to 100% by mass, and more preferably 70 to 90% by mass, relative to 100% by mass of the detergent composition.

Examples of the polyethylene-based resin include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, a copolymer of ethylene and α-olefin, and a resin such as a propylene-ethylene copolymer. Among them, high-density polyethylene, low-density polyethylene, and linear low-density polyethylene are preferable because they are excellent in cleaning performance and easy substitution. In particular, it is more preferable to use high-density polyethylene as the polyethylene resin having the highest melting point and low-density polyethylene as the polyethylene resin having the lowest melting point, from the viewpoint of further superior cleaning performance and easy substitution.

The weight average molecular weight of the polyethylene resin is not particularly limited, but is preferably less than 1,000,000, more preferably 50,000 or more and less than 1,000,000, and further preferably 200,000 to 300,000. In the present embodiment, the weight average molecular weight is a value measured by gel permeation chromatography (GPC).

The melt flow rate of the polyethylene resin is preferably 0.01 g/10 minutes or more from the viewpoint of excellent detergency and easy substitution with the molding material used after washing. It is more preferably 20 g/10 minutes or less, further preferably 0.05 to 10 g/10 minutes.
Here, the melt flow rate of the polyethylene-based resin means that measured according to ISO R1133, and the measurement conditions are 190° C. and 2.16 kg load.
When a plurality of polyethylene-based resins are used, it is preferable to adjust those within the above range by mixing those within the above melt flow range and those outside the above melt flow rate range.

<Polyolefin resin that does not substantially flow above the melting point>
The detergent composition of the present embodiment preferably further contains 1 to 20 mass% of a polyolefin resin that does not substantially flow at a temperature exceeding the melting point of the resin.
Here, the “temperature above the melting point of the resin” refers to any temperature above the melting point, and may be 20 to 80° C. higher than the melting point.
Further, “substantially does not flow” means that the value of the melt flow rate measured under the conditions of an arbitrary temperature satisfying a temperature exceeding the melting point of the above resin and a load of 21.6 kg is 0 according to ISO R1133. It means less than or equal to 1 g/10 minutes.
By adding a polyolefin resin that does not substantially flow, the viscosity of the polyethylene resin can be increased and the detergency can be increased. It is also preferable from the viewpoint of cleaning the resin burnt, which cannot be removed by only the high-viscosity resin. Further, it is less likely to remain in the next molding material as compared with the inorganic additive and is easily replaced, and is preferable from the viewpoint of wear of the cylinder and screw inside the molding machine.

Examples of the polyolefin resin that does not substantially flow at a temperature above the melting point of the resin include ultra-high molecular weight polyolefin or cross-linked polyolefin-based resin. Among them, the ultra-high molecular weight polyolefin has cleaning performance and easy substitution (residual property). From the viewpoint of.

The ultra-high molecular weight polyolefin means a polymer of an alkene containing ethylene as a main constituent and having a weight average molecular weight of 1,000,000 or more. The weight average molecular weight is preferably 2 to 12 million, more preferably 4 to 10 million. Further, the ultra-high molecular weight polyolefin is preferably ultra-high molecular weight polyethylene. Ultra-high molecular weight polyethylene has a weight average molecular weight larger than that of the above polyethylene resin and is not included in the above polyethylene resin.
Examples of the crosslinked polyolefin include those obtained by crosslinking a polyolefin resin by irradiating it with an electron beam or gamma ray, and by crosslinking a polyolefin resin with a crosslinking agent such as an organic peroxide and heating the mixture. ..

The polyolefin resin that does not substantially flow at a temperature exceeding the melting point of the resin is preferably 1 to 50% by mass with respect to 100% by mass of the detergent composition in terms of the balance of cleaning performance and easy substitution. The amount is more preferably 1 to 30% by mass, further preferably 1 to 20% by mass, and particularly preferably 5 to 20% by mass. Further, from the viewpoint of excellent cleaning property for removing the burn, 20% by mass or more is preferable.

When a cleaning agent with a weak cleaning power is used, the previous molding material not only remains in the resin molding machine and enters the next molding material as foreign matter, but it also remains when the molding machine is stopped. Is deteriorated, and when the molding machine is started again, it becomes a deteriorated product and mixes in easily. Therefore, as a method for enhancing the detergency of the detergent for the purpose of avoiding this problem, for example, a thermoplastic resin as a base material, an inorganic filler or a surfactant for enhancing the detergency, a lubricant, a cross-linked polymer, You may mix|blend additives, such as a high molecular weight polymer and a foaming agent.
In addition, if a cleaning agent with a low level of easy replacement is used to clean the inside of the resin molding machine, it will take a long time to replace it with the molding material used next, and the loss of molding material will increase, resulting in a decrease in production efficiency. There is something to do. If the additive amount of the above-mentioned inorganic filler or the like is excessive, the easy-displacement property is deteriorated. Therefore, it is preferable that the additive amount is set to make a good balance between the cleaning performance and the easy-displacement property.

<Filler>
The detergent composition of the present embodiment preferably further contains 1 to 20% by mass of a filler.

As the above-mentioned filler, known fillers used in conventional resin films and resin sheets are used without particular limitation, and both natural substances and artificial synthetic substances can be used. When the inorganic filler is contained, the effect of physically scraping off the resin remaining inside the molding machine can be obtained.

Specific examples of the inorganic filler include calcium carbonate, magnesium carbonate, metal carbonates such as barium carbonate, calcium sulfate, metal sulfates such as barium sulfate, kaolin, clay, silicates such as diatomaceous earth, and other oxides. Titanium, aluminum hydroxide, magnesium hydroxide, zeolite, talc, mica, wollastonite, xonotlite, montmorillonite, bentonite, sepiolite, imogolite, sericite, lawsonite, smectite, glass fiber, glass beads, silica, alumina and the like. Particularly preferred are calcium carbonate, barium sulfate talc, mica, wollastonite, glass fiber, glass beads, silica and alumina. Among them, when used in combination with at least two types of polyethylene-based resins having a difference between the maximum melting point and the minimum melting point of 15° C. or higher (particularly 20° C. or higher), particularly excellent cleaning performance and easy substitution are obtained. Therefore, calcium carbonate or glass fiber is more preferable, glass fiber is particularly preferable from the viewpoint of particularly excellent cleaning performance, and calcium carbonate is particularly preferable from the viewpoint of particularly excellent balance between cleaning performance and easy substitution.
These may be used alone or in combination of two or more.

The average particle size of the filler is not particularly limited, but is preferably 0.1 to 100 μm, more preferably 0.5 to 50 μm, and particularly preferably 1 to 30 μm. This average particle diameter can be determined by a laser diffraction method (for example, using SALD-2000 manufactured by Shimadzu Corporation).

From the viewpoint of sufficiently obtaining the effect of physically scraping off the resin remaining inside the resin molding processing machine, the viewpoint of easy substitution, and the stable extrusion processability of the detergent composition, the mass ratio of the filler is Is preferably 1 to 50% by mass, more preferably 1 to 30% by mass, further preferably 1 to 20% by mass, particularly preferably 5 to 20% by mass, relative to 100% by mass of the detergent composition. Is. For example, when calcium carbonate is used, it is preferably 2 to 8 mass% from the viewpoint of particularly excellent ease of substitution.

<Other additives>
The cleaning composition of the present embodiment may further contain at least one additive selected from the group consisting of lubricants, mineral oils, surfactants, and fluorinated compounds depending on the application.

-Lubricant-
The detergent composition of this embodiment may contain a lubricant. Examples of the lubricant include the lubricants used for the above plastic material applications. Specific examples of the lubricant include fatty acid alkali metal salts, fatty acid wax, fatty acid ester wax and the like, and montanic acid ester wax is particularly preferable. Further, polyethylene wax, polypropylene wax, low molecular weight polyethylene, and low molecular weight polypropylene can also be used as the lubricant. Low molecular weight polyethylene and low molecular weight polypropylene mean those having a weight average molecular weight of less than 50,000. These may be modified with other resins, acids, bases or the like depending on the application. The above lubricants may be used alone or in combination of two or more.
It should be noted that the polyethylene resin does not include polyethylene as the lubricant.

-Mineral oil-
The above-mentioned mineral oil is an oil obtained by refining petroleum, and is a saturated hydrocarbon oil containing mineral oil, lubricating oil, naphthene, also called liquid paraffin, and isoparaffin. Mineral oil having a wide viscosity range can be used. For example, in the case of liquid paraffin, the viscosity of which is 50 to 500 measured by JIS K2283, the Redwood method (Japan Oil Chemistry Association standard oil and fat analysis test method 2.2. The viscosity measured according to 10.4-1996) in the range of 30 to 2000 may be used.

-Surfactant-
Examples of the above surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. Of these, a liquid surfactant at room temperature is preferable. Examples of the anionic activator include higher fatty acid alkali salts, alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, sulfosuccinate ester salts and the like. Specific examples of the cationic activator include higher amine halogen acid salts, alkylpyridinium halides, quaternary ammonium salts and the like. Specific examples of the nonionic activator include polyethylene glycol alkyl ether, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, and fatty acid monoglyceride. Specific examples of the amphoteric surfactant include amino acids.
The above-mentioned surfactants may be used alone or in combination of two or more.

-Fluorinated compound-
The fluorinated compound may be polytetrafluoroethylene, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, or the like, but is more preferably the acrylic-modified compound. Particularly preferable are polytetrafluoroethylene modified with an acrylic resin and copolymers thereof.
The above fluorinated compounds may be used alone or in combination of two or more.

The detergent composition of this embodiment is particularly suitable for resin molding processing machine applications. Among them, from the viewpoint of obtaining a more excellent effect, it is suitable for washing after processing of a molded article containing polyethylene (in particular, a molded article containing 50% by mass or more of high-density polyethylene).

[2] Method for producing detergent composition The method for producing the detergent composition according to this embodiment is not particularly limited. As a preferred production method, a resin composition containing the above-mentioned polyethylene resin and other components optionally blended is melt-kneaded using a kneader, an extruder or a melt-kneading device such as a Banbury mixer to obtain a resin composition. An example of the method is a method including a step of extruding the melt-kneaded product into a strand shape and then forming it into particles. As the melt-kneading device used here, an extruder is preferable, and a twin-screw extruder is more preferable, from the viewpoint that the polyethylene resin and the inorganic filler can be sufficiently kneaded. By using the twin-screw extruder as described above, the inorganic compound is less likely to aggregate in the process of melting and kneading the polyethylene resin, the ultra-high molecular weight polyolefin and the inorganic filler, and the inorganic compound is uniformly dispersed in the polyolefin thermoplastic resin. Since it becomes easier, the extrudability tends to be stable, and the pulsation of the strands discharged from the extruder tends to be suppressed.

When blending and melt-kneading various components, commonly used equipment, for example, tumbler, ribbon blender, premixing equipment such as super mixer, gravimetric feeder, single-screw extruder or twin-screw extruder, A melt-kneading device such as a cokneader can be used. In addition, when melt-kneading, open deaeration that removes mood from the opening (vent) under normal pressure, and depressurization deaeration that reduces pressure to remove mood from the opening (vent) if necessary. Is desirable.

The cylinder temperature during melt-kneading with an extruder is preferably set to 300°C or lower, more preferably 280°C or lower, further preferably 260°C or lower, and particularly preferably 240°C or lower. Since it is desirable that the residence time of the molten resin in the extruder be as short as possible, the cylinder temperature is set in consideration of this viewpoint.

In the method for producing a detergent composition according to the present embodiment, the polyethylene resin may be used as polyethylene resin particles.
The polyethylene-based resin particles can be obtained by cutting a strand obtained by molding a raw material containing a polyethylene-based resin with an extruder or the like.
The shape of the polyethylene resin particles is not particularly limited as long as the effect of the present invention is not impaired, but examples thereof include a cylindrical shape, a spherical shape, a flake shape, and a powder shape.
When the shape of the polyethylene-based resin particles is columnar, it is preferable that the minor axis is 2-3 mm, the major axis is 3-5 mm, and the length is 3-5 mm. In the present embodiment, the minor axis, major axis and length are values measured with a caliper or the like.
The polyethylene resin particles may have an oil layer on the surface. An oil layer can be formed by adhering the above-mentioned mineral oil or surfactant to the surface of the polyethylene resin particles. The oil layer does not need to be formed on the entire surface of the polyethylene resin particles, and may be formed on at least a part thereof, but from the viewpoint of easy replacement of the detergent composition, it is formed on the entire surface. Preferably. From the viewpoint of easy handling, it is preferable that a lubricant is attached to the oil layer. Here, the above-mentioned lubricant can be used as the lubricant. A detergent composition including polyethylene-based resin particles having an oil layer and having a lubricant adhered thereto tends to have high replaceability.
The oil layer can be formed by using a tumbler blender, a blender for resin processing such as a super mixer, and simultaneously adding and blending polyethylene-based resin particles and oil. When the lubricant is applied, it can be applied by forming an oil layer on the surface of the polyethylene resin particles and then adding the lubricant to a resin processing blender such as a tumbler blender or a super mixer and blending.

The above polyethylene resin particles may be used as they are as a detergent composition, or a suitable polyolefin resin, that is, a resin pellet of high-density polyethylene, linear low-density polyethylene, low-density polyethylene, or polypropylene with a suitable ratio. You may use what was mixed in above as a cleaning composition.

[3] Method for Cleaning Resin Molding Machine The method for cleaning a resin molding machine according to the present embodiment uses the above-mentioned detergent composition.
Further, the method for cleaning a resin molding processing machine according to the present embodiment may have a step of allowing the above-mentioned detergent composition to stay in the resin molding processing machine.
Specific examples of the resin molding machine include an injection molding machine and an extrusion molding machine.
The cleaning method of the resin molding processing machine according to the present embodiment can not only efficiently discharge the material molded and processed before cleaning, but also when the resin molding processing machine is stopped after cleaning, Even if the material that has been molded before the cleaning is left in the resin molding machine due to insufficient cleaning, it is possible to prevent thermal deterioration of the remaining material by allowing the material to stay in the molding machine in a filled state. is there.

[4] Method of Using Cleaning Agent Composition The cleaning agent composition for a resin molding machine according to the present embodiment can be used as it is as a cleaning agent composition. The cleaning composition for a resin molding processing machine of the embodiment can be used by being mixed with a subsequent material. The mixing ratio is preferably 100 to 900 parts by weight of the succeeding material with respect to 100 parts by weight of the detergent composition for resin molding processing machine, and more preferably 100 parts by weight of the succeeding material with respect to 100 parts by weight of the detergent composition for resin molding processing machine. It is 200 to 750 parts by weight, and more preferably 300 to 600 parts by weight of the succeeding material with respect to 100 parts by weight of the detergent composition for a resin molding machine. The subsequent material is preferably an olefin resin, and particularly preferably high density polyethylene, low density polyethylene, or linear low density polyethylene.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The components used in the examples or comparative examples are as follows. The present embodiment is not limited to the following examples as long as the gist thereof is not exceeded.

(1) Component (A): Polyethylene resin The following components (A1 to A4) were used as the polyethylene resin.
In this example, the melt flow rate of each thermoplastic resin was measured according to ISO R1133 under the conditions of a temperature of 190° C. and a load of 2.16 kg.
The density was measured according to JIS K7112.
The melting point was determined by differential scanning calorimetry (DSC) according to JIS K7121. A small piece of 5 mg of sample resin is enclosed in an aluminum pan, placed on a sample stand of a DSC measuring device, and the temperature is raised from 20° C. to 200° C. at a rate of 20° C./min as the first temperature rise, and after reaching 200° C., 2 minutes Held Next, the temperature is lowered from 200° C. to 20° C. at a rate of 20° C./minute, and after reaching 20° C., the temperature is held for 2 minutes, and then, as the second heating, the temperature is raised from 20° C. to 200° C. at a rate of 20° C./minute, The temperature of the peak of the DSC curve obtained when the temperature was raised for the first time was taken as the melting point of the sample resin.
HiZex 5100B (made by Prime Polymer Co., Ltd.) was used as the polyethylene-based resin (A1) (high-density polyethylene). The polyethylene resin (A1) had a melt flow rate of 0.27 g/10 minutes, a density of 0.944 kg/m ³ , and a melting point of 126°C.
-Suntech B770 (made by Asahi Kasei Corporation) was used as polyethylene-based resin (A2) (high-density polyethylene). The polyethylene resin (A2) had a melt flow rate of 0.16 g/10 minutes, a density of 0.953 kg/m ³ , and a melting point of 132°C.
-Suntech M2206 (manufactured by Asahi Kasei Corporation) was used as the polyethylene-based resin (A3) (low-density polyethylene). The polyethylene resin (A3) had a melt flow rate of 0.6 g/10 minutes, a density of 0.923 kg/m ³ , and a melting point of 111°C.
-UBE polyethylene B028 (manufactured by Ube Maruzen Polyethylene Co., Ltd.) was used as the polyethylene resin (A4) (low density polyethylene). The polyethylene resin (A4) had a melt flow rate of 0.4 g/10 minutes, a density of 0.927 kg/m ³ , and a melting point of 114°C.

(2) Component (B): Ultra High Molecular Weight Polyolefin As the ultra high molecular weight polyolefin, Sunfine UH950 (manufactured by Asahi Kasei Corporation) was used. The ultra high molecular weight polyethylene had a molecular weight of 4.5 million.
When 3 g of Sunfine UH950 was used to measure the fluidity at a temperature 54° C. higher than the melting point of 136° C. with a melt flow rate measuring device, the melt flow rate was 0.1 g/10 minutes or less. It was a polyolefin resin that did not substantially flow.

(3) Component (C): Filler The following components (C1 to C2) were used as the inorganic filler.
-Calcium carbonate KK3000 (made by Yabashi Industry Co., Ltd.) was used as the inorganic filler (C1) (calcium carbonate, CC).
-As the inorganic filler (C2) (glass fiber, GF), ECS03T-351 (manufactured by Nippon Electric Glass Co., Ltd., containing a sizing agent, a coupling agent, an average fiber diameter of 13 µm, an average fiber length of 3000 µm, a coupling agent 2000 ppm) was used.

[Preparation of Cleaning Agent Compositions (Examples 1 to 7 and Comparative Examples 1 to 3)]
A resin composition containing each component in a ratio shown in Table 1 was preliminarily mixed for 5 minutes using a tumbler blender, and the obtained mixture was melt-kneaded. The melt-kneading was performed using a twin-screw extruder (manufactured by Ikegai Co., Ltd., equipment: PCM30) under the conditions of a cylinder set temperature of 210° C. and a supply rate of 15 kg/h. The melt-kneaded product discharged from the extruder was extruded into a strand, cooled with water, and then cut with a strand cutter to obtain pellet-like samples of each cleaning composition.

Evaluation of Detergent Composition With respect to the obtained detergent composition samples, the following detergency and detergency were evaluated. The evaluation results are shown in Table 1.

<Evaluation of washability (evaluation of color changeability)>
A low-density polyethylene (Suntech M1920 manufactured by Asahi Kasei Co., Ltd.) colored in blue is used as a coloring masterbatch, 10 parts by mass of the coloring masterbatch and 90 parts by mass of high-density polyethylene (Suntech B161 manufactured by Asahi Kasei) are mixed, and an injection molding machine is used. (IS-60B manufactured by Toshiba Machine Co., Ltd.), 1 kg was charged, the screw position was set to the forward limit, the screw was rotated, and the resin mixture was discharged from the nozzle to attach pseudo dirt to the inside of the injection molding machine.
After that, 1 kg of the cleaning composition sample was put into the injection molding machine, and when cleaning was performed by screw rotation under the condition of a cylinder temperature of 220° C., while visually observing the color tone of the purging waste discharged from the nozzle, the cleaning was performed. The purged scraps were discharged until the above procedure was completed, and the discharged purged scraps amount (kg) was measured by a balance.
The smaller the amount of the discharged purging waste, the better the cleaning property. Note that the cleaning waste was completed when the purged waste discharged from the nozzle during cleaning was cooled to room temperature and solidified, but the color tone changed from blue to white.

<Easy substitution evaluation (residual evaluation)>
After the above-mentioned evaluation of the cleanability, 1 kg of high-density polyethylene (Suntech B161 manufactured by Asahi Kasei Co., Ltd.) was charged into the injection molding machine, and the purging waste discharged from the nozzle was replaced by screw rotation at a cylinder temperature of 220°C. The degree of turbidity in the molten state was visually observed.
The amount (kg) of purge dust discharged until the appearance of the purge dust in the molten state became completely transparent was measured by a balance. The smaller the amount of purged scraps discharged, the better the ease of replacement.

<Cleaning power evaluation (burn removal performance evaluation)>
100 g of nylon 66 resin (Leona 14G33 manufactured by Asahi Kasei Co., Ltd.) was put into a small extruder (Plasticorder manufactured by Brabender Co.) heated to 280° C., the screw was rotated, and the nylon 66 resin was discharged from the nozzle. Nylon 66 resin was deposited in the small extruder. The nylon 66 resin was left to stand for 1 hour at 280° C., and burnt of the remaining nylon 66 resin inside the extruder was produced. After that, the set temperature was lowered to 220° C., 150 g of the detergent composition sample was charged into the small extruder, and while observing the color tone of the purging waste discharged from the nozzle visually, the purging waste was removed until the cleaning was completed. The amount of purged scraps (g) discharged was measured with a balance.
The smaller the amount of the discharged purging waste, the better the cleaning property. The cleaning was completed when all the burned nylon 66 resin (brown discoloring resin) was discharged and the color of the sample was changed.

As is apparent from the above results, the cleaning composition for a resin molding processing machine of the present invention exhibits excellent cleaning performance, and also has an excellent balance between cleaning performance and easy substitution, and the thermoplastic resin ( Particularly, it is useful as a detergent composition for a molding processing machine of a molding material containing high-density polyethylene).

Claims (6)

A detergent composition for a resin molding machine, comprising at least two types of polyethylene-based resin, wherein the difference between the maximum melting point and the minimum melting point of the polyethylene-based resin is 15°C or more. The cleaning composition for a resin molding machine according to claim 1, comprising 1 to 20% by mass of a polyolefin resin that does not substantially flow at a temperature exceeding a melting point of the resin, relative to 100% by mass of the cleaning composition. .. The cleaning composition for a resin molding machine according to claim 2, wherein the polyolefin resin is an ultra-high molecular weight polyolefin. The cleaning composition for a resin molding processing machine according to any one of claims 1 to 3, which contains 1 to 20% by mass of a filler with respect to 100% by mass of the cleaning composition. The cleaning for a resin molding machine according to claim 4, wherein the filler is at least one selected from calcium carbonate, talc, mica, wollastonite, glass fiber, glass beads, silica, alumina, and barium sulfate. Agent composition. A method for cleaning a resin molding machine using the detergent composition for a resin molding machine according to any one of claims 1 to 5.