JP2023031305A - Detergent for molding machine, usage thereof, and method for cleaning molding machine - Google Patents

Abstract

To provide a detergent for a molding machine having excellent cleaning performance (removal of burns and the like, and color-changing), and replacement easiness by a molding material after cleaning.SOLUTION: A detergent for a molding machine contains an ultra-high molecular weight polyethylene (A) and a thermoplastic resin (B) other than the ultra-high molecular weight polyethylene (A). The ultra-high molecular weight polyethylene (A) is compatible or dispersed in the detergent for a molding machine. If dispersed, an average particle diameter of the ultra-high molecular weight polyethylene (A) is 90 μm or less.SELECTED DRAWING: None

Description

The present invention relates to a molding machine cleaner, its use, and a method of cleaning a molding machine using the molding machine cleaner.

In general, resin molding machines such as extruders and injection molding machines are used for operations such as coloring, mixing, and molding of resins. In addition to additives such as dyes and pigments contained in molding materials, degraded products (thermal decomposition products, burns, carbides, etc.) generated from resins etc. may remain in the molding machine. If this residue is left unattended, the residue will be mixed into the molded product during the subsequent resin molding process, which may cause poor appearance of the product. In particular, when a transparent resin is molded, even a minute amount of carbide or the like is easily visible. Therefore, it is desired to completely remove the residue from inside the molding machine.

Conventionally, in order to remove the residue from the inside of the molding processing machine, (1) a method of manually disassembling and cleaning the molding processing machine, (2) the molding material to be used for the next molding as it is without stopping the molding processing machine. (3) a method of using a cleaning agent; and the like.
The method (1) above is inefficient because it requires the molding machine to be stopped, and the molding machine is likely to be damaged because the removal work is done physically by hand. The above method (2) often requires a large amount of molding material to remove the residue, takes time to complete the work, and has the problem of generating a large amount of waste. . Therefore, in recent years, the method (3) using a cleaning agent has come to be preferred because of its excellent cleaning power for removing residues in molding machines.

Various techniques for enhancing the detergency of detergents have been proposed for the purpose of enhancing the effects of detergents. For example, Patent Literatures 1 and 2 describe a method of enhancing detergency by blending a thermoplastic superpolymer.

JP-A-8-155969 JP 2019-218566 A

The detergent is required to have high detergency against the molding material used in the previous molding and to be easily replaced by the molding material used in the next molding. In order to achieve a high detergency that can deal with strong stains such as burns derived from resin, it is often the case that a method of blending a large amount of additives (inorganic fillers, ultra-high molecular weight resins, etc.) with a scrubbing effect is taken. It is difficult to discharge the added components that have accumulated in the processing machine, and the problem is that the replaceability is hindered.
In the cleaning agent described in Patent Document 1, the thermoplastic ultra-high polymer is blended to improve the cleaning performance, but the thermoplastic ultra-high polymer stays in the molding machine, and the cleaning agent separates the next molding material. There was a problem that it takes a lot of resin amount and time to replace with.
In the cleaning agent of Patent Document 2, fluidity is enhanced by adding a condensed hydroxy fatty acid and/or its alcohol ester when kneading the thermoplastic ultra-high polymer and the thermoplastic resin. Further improvement is desired in terms of balance with ease of replacement with subsequent molding materials.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cleaning agent for a molding machine which is excellent in cleaning performance (removal of scorch, etc., color change) and easy replacement with a molding material after cleaning.

As a result of intensive studies to solve the above problems, the present inventors have focused on the state of dispersion of ultra-high molecular weight polyethylene in a cleaning agent for molding machines. The inventors have found that by controlling the dispersion to have an average particle size within a specific range, the cleaning agent can be easily replaced without remaining in the molding machine, leading to the development of the present invention.

That is, the present invention is as follows.
[1]
A molding machine cleaning agent comprising an ultra-high molecular weight polyethylene (A) and a thermoplastic resin (B) other than the ultra-high molecular weight polyethylene (A), wherein the ultra-high molecular weight polyethylene (A) is the molding machine cleaning agent. A detergent for a molding machine, characterized in that it is compatible with or dispersed in the agent, and when dispersed, the ultra-high molecular weight polyethylene (A) has an average particle size of 90 μm or less.
[2]
The cleaning agent for a molding machine according to [1], further comprising an aliphatic hydrocarbon compound (C) having a weight average molecular weight of 200 or more and 20,000 or less.
[3]
The cleaning agent for a molding machine according to [2], wherein the content of the aliphatic hydrocarbon compound (C) is 0.01% by mass or more and 20% by mass or less.
[4]
The cleaning agent for molding machines according to any one of [1] to [3], wherein the thermoplastic resin (B) contains at least one type of polyolefin resin.
[5]
The detergent for molding machines according to any one of [1] to [4], wherein the content of the ultra-high molecular weight polyethylene (A) is 20% by mass or more and 80% by mass or less.
[6]
The detergent for molding machines according to any one of [1] to [5], wherein the ultra-high molecular weight polyethylene (A) has a weight average molecular weight of 400,000 or more and 1,000,000 or less.
[7]
The cleaning agent for molding machines according to any one of [1] to [6], further comprising an organic acid metal salt (D).
[8]
A method for cleaning a molding machine, comprising using the cleaning agent for a molding machine according to any one of [1] to [7].
[9]
Use of the cleaning agent for molding machines according to any one of [1] to [7] in cleaning molding machines.

ADVANTAGE OF THE INVENTION According to this invention, the cleaning agent for molding machines which is excellent in washing|cleaning performance (removal of burn|burn etc., color change) and easy replacement|exchangeability with the molding material after washing|cleaning can be provided.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. It should be noted that the present invention is not limited to the present embodiment described below, and various modifications can be made within the scope of the gist of the present invention.

[Cleaning agents for molding machines]
The cleaning agent for a molding machine of the present embodiment (hereinafter sometimes simply referred to as "cleaning agent" or "cleaning composition") comprises ultra-high molecular weight polyethylene (A) and the ultra-high molecular weight polyethylene (A) and a thermoplastic resin (B) other than the above, and the ultra-high molecular weight polyethylene (A) is compatible or dispersed in the molding machine cleaning agent, and when dispersed, the ultra-high molecular weight polyethylene (A) has an average particle size of 90 μm or less.

Each component and the like of the cleaning agent of the present embodiment will be described in detail below.

[[ultra-high molecular weight polyethylene (A)]]
The ultra-high molecular weight polyethylene (A) contained in the cleaning agent for molding machines of the present embodiment is not particularly limited, and may be an ethylene homopolymer or a copolymer of ethylene and one or more other monomers. is mentioned. In addition, a copolymer refers to a copolymer having a content of structural units derived from ethylene of 50% by mass or more.
Examples of the other monomer include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1 - α-olefins such as decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosane; vinyl compounds such as vinyl acetate; aliphatics such as acrylic acid, methacrylic acid, fumaric acid, and maleic acid Unsaturated carboxylic acids; aliphatic unsaturated carboxylic acid esters such as acrylic acid esters, methacrylic acid esters, fumaric acid esters and maleic acid esters.
Among the above ultra-high molecular weight polyethylenes, ethylene homopolymers are preferred.
The ultra-high molecular weight polyethylene (A) may be used singly or in combination of two or more.

The ultra-high molecular weight polyethylene (A) is compatible with or dispersed in the cleaning agent for molding machines.
Ultra-high molecular weight polyethylene (A) is dispersed in a cleaning agent for a molding machine. When observed at a magnification of 100 to 10000 times using Hitachi Ltd.'s H-7600), the morphology of the cleaning agent for molding machines is such that ultra-high molecular weight polyethylene (A) acts as a dispersed phase (island) in the matrix phase (sea). This means that it has a sea-island structure distributed over a wide area.
The average particle size of the ultra-high molecular weight polyethylene (A) when dispersed is 90 µm or less, preferably 85 µm or less, and more preferably 80 µm or less. When the average particle size is 90 µm or less, retention of the cleaning agent for molding machines in the molding machine is reduced, and easy replacement tends to be excellent.
In addition, when the ultra-high molecular weight polyethylene (A) is compatible with the cleaning agent for molding machines, when observed with the above equipment and magnification, ultra It means a state in which dispersed phases (islands) of high-molecular-weight polyethylene (A) are not observed or phase separation is not observed. When the ultra-high molecular weight polyethylene (A) is compatible with the cleaning agent for molding machines, it tends to be excellent in easy substitution.
Ultra high molecular weight polyethylene (A) is compatible with the cleaning agent for molding machines, or dispersed with an average particle size of 90 μm or less. A method of using a low molecular weight polyethylene (A), a method of selecting a special grade with a small particle size of powder among ultra-high molecular weight polyethylene (A), a method of using a screw with a high kneading degree during extrusion kneading, a temperature during extrusion kneading can be set higher.
The morphology of the cleaning agent for the molding machine is obtained by exposing the cross section of the cleaning agent pellet with a microtome, and observing the cross section with a digital microscope (eg, Keyence VHX-5000) or a transmission electron microscope (eg, It shall be confirmed by observing at a magnification of 100 to 10,000 times using H-7600 manufactured by Hitachi, Ltd. When using a transmission electron microscope, after embedding and molding the pellet in epoxy resin, an ultra-thin section prepared using a cryo-ultramicrotome shall be stained with an electron beam using ruthenium tetroxide vapor for observation.
In addition, the average particle size of the ultra-high molecular weight polyethylene (A) is obtained by measuring the area of the island-shaped domain from the binarized image of the observed image and calculating the equivalent circle diameter as the particle size. This value is obtained by calculating the average value of particle diameters for the shape domain.
When a component that becomes an island-shaped domain (dispersed) is included in addition to the ultrahigh molecular weight polyethylene (A), the domain of the component can be measured by microscopic infrared spectroscopy, Raman spectroscopy, or the like in the case of a large-sized domain. In the case of small-sized domains, elemental mapping such as scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) for inorganic substances, and transmission electron microscopy using staining for organic substances. By using, the composition in the domain can be confirmed and distinguished from the domain of ultrahigh molecular weight polyethylene (A).

The ultra-high molecular weight polyethylene (A) preferably has a weight average molecular weight of 400,000 or more and 1,000,000 or less, more preferably 400,000 or more and 900,000 or less, and still more preferably 400,000 or more and 800,000 or less. When the weight-average molecular weight is within the above range, the ultra-high molecular weight polyethylene (A) is compatible with the cleaning agent for molding machines, or easily dispersed with an average particle size of 90 μm or less, thereby tending to be excellent in easy substitution. . In addition, when the weight average molecular weight is within the above range, it becomes easier to manufacture a cleaning agent for molding machines containing ultra-high molecular weight polyethylene (A) at a higher ratio than before, and the cleaning performance (color change, burning, etc.) is better than before. etc.) also tends to be excellent. The higher the weight-average molecular weight of the ultra-high molecular weight polyethylene (A), the more the fluidity is hindered and the detergent stays in the molding machine, requiring more resin and time to replace the detergent with the molding material. Especially in extrusion molding, this problem is conspicuous because the molding machine and the resin flow path inside the die are very complicated. In addition, the higher the weight average molecular weight of the ultra-high molecular weight polyethylene (A), the more ultra-high-molecular weight polyethylene (A) contained, the motor of a kneader such as a twin-screw extruder during kneading of the cleaning composition. The load (torque) increases, and the production of the cleaning composition tends to become difficult.
The weight average molecular weight of the ultra-high molecular weight polyethylene (A) is a value measured using gel permeation chromatography (GPC), and specifically, it can be obtained by the method described in Examples below. can. Also, the molecular weight distribution of the components contained in the detergent composition can be confirmed by using GPC.

The content of ultra-high molecular weight polyethylene (A) is preferably 20 to 80% by mass, more preferably 20 to 70% by mass, and still more preferably 30 to 60% by mass with respect to 100% by mass of the cleaning composition. % or more. When the content of the ultra-high molecular weight polyethylene (A) is 20% by mass or more, the cleaning agent for molding machines of the present embodiment tends to be excellent in cleaning performance (removal of color change, burning, etc.). When the content is 80% by mass or less, the easy substitution tends to be excellent, and the motor load applied to a kneader such as a twin-screw extruder when kneading the detergent composition causes a problem in kneading. range.

The method for producing the ultra-high molecular weight polyethylene (A) is not particularly limited, and it can be produced by a conventionally known method using a known catalyst such as a Ziegler-Natta catalyst.

[[Thermoplastic resin (B)]]
The thermoplastic resin (B) contained in the cleaning agent for molding machines of the present embodiment is not particularly limited as long as it is a thermoplastic resin other than ultra-high molecular weight polyethylene (A), and is used for general injection molding, extrusion molding, and the like. A wide variety of thermoplastic resins can be used.
Examples of the thermoplastic resin (B) include polyolefin resins, ethylene-vinyl acetate copolymer resins, ethylene-aliphatic unsaturated carboxylic acid copolymer resins such as ethylene-acrylic acid copolymers, and ethylene-acrylic acid ester copolymers. Examples include ethylene-aliphatic carboxylic acid ester copolymer resins such as polymers, ionomer resins, styrene resins such as polystyrene, polycarbonate resins, polyamide resins, polyester resins, and polyvinyl chloride resins.
The thermoplastic resin (B) may be used alone or in combination of two or more.

As the polyolefin-based resin, polyethylene-based resins other than ultra-high molecular weight polyethylene (A), polypropylene-based resins, and polybutene-based resins are preferable. Here, the polyethylene-based resin is a homopolymer of ethylene, or a copolymer of ethylene and one or more other monomers, in which the content of structural units derived from ethylene is 50% by mass. Show above. The polypropylene-based resin is a homopolymer of propylene, or a copolymer of propylene and one or more other monomers, in which the content of structural units derived from propylene is 50% by mass or more. of the Furthermore, the polybutene resin is a butene homopolymer or a copolymer of butene and one or more other monomers, wherein the content of structural units derived from butene is 50% by mass or more. Show things.

Examples of the polyethylene-based resin include polyethylene, ethylene-α-olefin copolymer, etc. Specific examples include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), linear ultra-low density polyethylene (VLDPE, ULDPE) and the like.

The ethylene-α-olefin copolymer is preferably a copolymer consisting of ethylene and at least one selected from α-olefins having 3 to 20 carbon atoms. More preferably, it is a copolymer comprising at least one selected from α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-decene, 1- Dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like can be mentioned, and these can be used alone or in combination of two or more.
As the ethylene-α-olefin copolymer, a copolymer of ethylene and at least one comonomer selected from propylene comonomer, butene comonomer, hexene comonomer and octene comonomer is generally readily available, It can be used preferably.

The polyethylene-based resin can be polymerized using a known catalyst such as a chromium-based catalyst, a Ziegler-based catalyst, or a metallocene-based catalyst. Chromium-based catalysts or metallocene catalysts having long branched molecular chains having 6 or more carbon atoms are preferred.

In addition, from the viewpoint of cleaning performance, the polyethylene resin preferably has an MFR (190° C., load 2.16 kg) of 0.01 to 30 g/10 min, more preferably 0.05 to 25 g/10 min. It is preferably 0.1 to 20 g/10 min, and more preferably 0.1 to 20 g/10 min.

Examples of the polypropylene-based resin include polypropylene, a propylene-α-olefin copolymer, and a terpolymer of propylene, ethylene and α-olefin.

The propylene-α-olefin copolymer is a copolymer composed of propylene and at least one selected from α-olefins. The propylene-α-olefin copolymer is preferably a copolymer composed of propylene and at least one selected from ethylene and an α-olefin having 4 to 20 carbon atoms. and at least one selected from α-olefins are more preferable. Examples of α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like can be mentioned, and these can be used alone or in combination of two or more. These copolymers may be in any form such as block copolymers and random copolymers, preferably random copolymers of propylene and ethylene.
As the propylene-α-olefin copolymer, a copolymer of propylene and at least one comonomer selected from ethylene comonomer, butene comonomer, hexene comonomer and octene comonomer is generally readily available and is preferably used. Available.

As the terpolymer of propylene, ethylene and α-olefin, a terpolymer of propylene, ethylene and α-olefin such as butene, hexene and octene can be preferably used. These terpolymers may be in any form such as block copolymers and random copolymers, preferably random copolymers of propylene, ethylene and butene.

The polypropylene-based resin may be not only a resin polymerized with a catalyst such as a Ziegler-Natta catalyst, but also a resin polymerized with a known catalyst such as a metallocene catalyst. Tactic polypropylene or the like can also be used.
Moreover, the polypropylene-based resin preferably has long-chain branches from the viewpoint of washing performance, and the branches can be introduced by grafting or polymerization by irradiation of ionizing radiation, for example.

From the viewpoint of washing performance, the polypropylene resin preferably has an MFR (230° C., load 2.16 kg) of 0.01 to 30 g/10 min, more preferably 0.05 to 25 g/10 min. More preferably, it is 0.1 to 20 g/10 min.

Since the polybutene-based resin has particularly excellent compatibility with the polypropylene-based resin, it is preferable to use the polybutene-based resin together with the polypropylene-based resin for the purpose of adjusting the melt viscosity.
As the polybutene-based resin, a crystalline copolymer composed of butene and at least one selected from ethylene, propylene and olefinic compounds having 5 to 8 carbon atoms can be suitably used.

The ethylene-vinyl acetate copolymer resin refers to a copolymer obtained by copolymerizing an ethylene monomer and a vinyl acetate monomer.
The ethylene-unsaturated aliphatic carboxylic acid copolymer resin refers to a copolymer obtained by copolymerizing an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acids. Examples of aliphatic unsaturated carboxylic acids include acrylic acid, methacrylic acid, fumaric acid, maleic acid and the like.
Furthermore, the ethylene-aliphatic unsaturated carboxylic acid ester copolymer resin refers to a copolymer obtained by copolymerizing an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acid esters. Examples of aliphatic unsaturated carboxylic acid esters include acrylic acid esters, methacrylic acid esters, fumaric acid esters, and maleic acid esters.
Copolymerization of the copolymer resin can be carried out by a known method such as a high-pressure method or a melting method, and a multi-site catalyst, a single-site catalyst, or the like can be used as a catalyst for the polymerization reaction. In addition, in the above copolymer, the bond shape of each monomer is not particularly limited, and a polymer having a bond shape such as random bond or block bond can be used.

The above-mentioned ionomer resin is a resin having ionic bonds between polymer structures, and an alkali metal or alkaline earth metal is bonded to a copolymer of ethylene and acrylic acid or methacrylic acid to form a crosslinked structure. A resin can be preferably used.

The styrenic resin is polystyrene or a copolymer of styrene and one or more other monomers in which the content of structural units derived from styrene is 50% by mass or more.
Other monomers to be copolymerized with styrene include, for example, acrylonitrile and butadiene.
Specific examples of styrene resins include polystyrene, styrene-acrylonitrile copolymers, styrene-butadiene-acrylonitrile copolymers, and the like.

The above-mentioned polycarbonate-based resin is a copolymer having a carbonate ester bond in the repeating unit of the main chain, and a method of reacting an aromatic dihydroxy compound and a carbonate precursor, a method of reacting an aromatic dihydroxy compound and a carbonate precursor (e.g. , phosgene) in the presence of an aqueous sodium hydroxide solution and a methylene chloride solvent (e.g., phosgene method), transesterification method in which an aromatic dihydroxy compound and a carbonic acid diester (e.g., diphenyl carbonate, etc.) are reacted. (melt method), a phosgene method, or a copolymer obtained by solid phase polymerization of a crystallized carbonate prepolymer obtained by a melt method.

The polyamide-based resin is an aliphatic polyamide-based copolymer or an aromatic polyamide-based copolymer having an amide bond in the repeating unit of the main chain, and includes nylon 6, nylon 6/66, metaxylylene adipamide (MYD6Ny) and the like can be preferably used.

The polyester resin is a copolymer having an ester bond in the repeating unit of the main chain, and polyethylene terephthalate obtained by polycondensation of terephthalic acid and ethylene glycol can be suitably used.

The content of the thermoplastic resin (B) is preferably 1 to 80% by mass, more preferably 5 to 80% by mass, and still more preferably 10 to 70% by mass, based on 100% by mass of the cleaning composition. be. When the content of the thermoplastic resin (B) is within the above range, the fluidity of the cleaning agent for molding machines tends to be good and the ease of replacement tends to be excellent.

[[Aliphatic hydrocarbon compound (C)]]
The molding machine cleaning agent of the present embodiment may contain an aliphatic hydrocarbon compound (C).
The aliphatic hydrocarbon compound (C) is not particularly limited as long as it has a weight average molecular weight of 200 or more and 20,000 or less, and examples thereof include mineral oil, paraffin wax, and olefin wax.
The above-mentioned ultra-high molecular weight polyethylene (A) and thermoplastic resin (B) do not contain the above-mentioned aliphatic hydrocarbon compound.

The mineral oil is an oil obtained by refining petroleum, and is a saturated hydrocarbon oil containing naphthene, isoparaffin, etc., which is also called mineral oil, lubricating oil, liquid paraffin, and the like. Mineral oils with a wide range of viscosities can be used. For example, in the case of liquid paraffin, those with a kinematic viscosity of 50 to 500 mm ² /s as measured by JIS K2283, the Redwood method (Japan Oil Chemists' Association standard oil analysis test method) 2.2.10.4-1996) having a viscosity in the range of 30 to 2000 (seconds) may be used.

The paraffin wax is a paraffin compound that is solid at room temperature and is obtained by refining petroleum, and one having a melting point of 40 to 80° C. is often used.
The olefin wax includes low-molecular-weight polyolefin and the like, and is not particularly limited, but general low-density or high-density polyethylene, polypropylene, and the like are used. Those having a weight average molecular weight of about 800 to 20,000 and a dropping point of 80 to 180° C. are most likely to exhibit the effect.

The content of the aliphatic hydrocarbon compound (C) is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.05 to 15% by mass, based on 100% by mass of the cleaning composition. , more preferably 0.1 to 10% by mass. When the content of the aliphatic hydrocarbon compound (C) is within the above range, it is possible to improve the ease of substitution while maintaining the washability. In addition, the addition of the aliphatic hydrocarbon compound (C) reduces the motor load (torque) of a kneader such as a twin-screw extruder during kneading of the cleaning composition, thereby facilitating the production of the cleaning composition. Become.

[[Organic acid metal salt (D)]]
The molding machine cleaning agent of the present embodiment may contain an organic acid metal salt (D). Inclusion of the organic acid metal salt (D) can improve washability and easy substitutability. In addition, by containing the organic acid metal salt (D), it is possible to suppress excessive increases in the motor load (torque) of a kneader such as a twin-screw extruder and the resin temperature during kneading of the cleaning composition. Processability is improved when manufacturing the composition.

The hydrocarbon moiety in the metal salt of the organic acid is preferably a saturated fatty acid having 9 to 28 carbon atoms, an unsaturated fatty acid having 9 to 28 carbon atoms, or benzoic acid. , palmitic acid, myristic acid, and lauric acid are more preferred.
The metal in the metal salt of the organic acid is not particularly limited, but includes sodium, potassium, lithium, cesium, magnesium, calcium, aluminum, zinc, iron, cobalt, barium and the like. Among them, lithium, calcium, barium, zinc, and aluminum are preferable because they exhibit the most effective lubricating effect. Among them, aluminum and zinc are more preferable because they have low polarity and tend to exhibit external lubricity due to bleeding out from the thermoplastic resin. Zinc is particularly preferred.

From the viewpoint of cleaning performance, the organic acid metal salt preferably has a surface tension of 32 mN/m or less. For example, zinc stearate has a surface tension of 24 mN/m, and aluminum stearate has a surface tension of 25 mN/m.
Also, the organic acid metal salt preferably has a melting point or softening point of 70° C. or higher, more preferably 80° C. or higher, and still more preferably 90° C. or higher.

The content of the organic acid metal salt (D) is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.05 to 10% by mass, based on 100% by mass of the cleaning composition. More preferably, it is 0.1 to 8% by mass. When the content of the organic acid metal salt (D) is within the above range, it is possible to enhance the washability and the easy substitutability.

[[Other additives]]
The cleaning agent of the present embodiment may contain other additives such as lubricants, surfactants, antioxidants, inorganic fillers, inorganic foaming agents, and ultrahigh molecular weight resins.
The content of other additives is preferably 10% by mass or less with respect to 100% by mass of the cleaning composition.

(Lubricant)
Examples of lubricants include organic acids, organic acid amides, organic acid derivatives such as organic acid esters, various ester waxes, fluorine resins, and the like, but are not particularly limited to these.
The above-mentioned lubricant does not include the above-mentioned aliphatic hydrocarbon compound (C) and organic acid metal salt (D).
The lubricant may be used singly or in combination of two or more.

As the organic acid, saturated fatty acids having 9 to 28 carbon atoms, unsaturated fatty acids having 9 to 28 carbon atoms, and benzoic acid are preferable. A part of the chain may have a hydroxyl group. In particular, stearic acid, palmitic acid, myristic acid, and lauric acid are more preferable from the viewpoint of availability and heat resistance. Mixed fatty acids having different alkyl chains may also be used. When the number of carbon atoms is within the above range, there is no problem of gas generation or odor, and it is easy to obtain and the properties as a lubricant at the interface function well, which is preferable.

Examples of the organic acid amide include saturated fatty acid amides, unsaturated fatty acid amides, saturated fatty acid bisamides, and unsaturated fatty acid bisamides having 9 to 28 carbon atoms. Among them, fatty acids having 12 to 18 carbon atoms such as lauric acid, myristic acid, palmitic acid, and stearic acid, unsaturated fatty acid amides such as erucic acid, and saturated fatty acid bisamides such as ethylenebisstearic acid amide are readily available. , and more preferably saturated fatty acid bisamide such as ethylenebisstearic acid amide, from the viewpoint of its effect as a lubricant.

Examples of the organic acid esters and ester waxes include polyol esters such as saturated fatty acid esters, unsaturated fatty acid esters, medium-chain fatty acid triglycerides, and hardened oils having 9 to 28 carbon atoms. From the standpoints of availability and effectiveness as a lubricant, stearate stearate, glycerin fatty acid ester monoglyceride, and the like are preferred.

Examples of the fluorine-based resin include PTFE, PFA, PVDF, PVDF-based copolymer, ETFE, and PFE, and are expected to have the effect of suppressing resin adhesion to metal surfaces. As for the shape, various shapes such as pellets and powders can be used, but powdery ones are particularly preferable in order to uniformly disperse them during processing. Although the average particle size is not particularly limited, it is preferably 1,000 μm or less.
The thermoplastic resin (B) does not include the fluororesin used as the lubricant.

From the viewpoint of cleaning performance, the lubricant preferably has a surface tension of 32 mN/m or less.
Also, the melting point or softening point of the lubricant is preferably 70° C. or higher, more preferably 80° C. or higher, and still more preferably 90° C. or higher.

The lubricant content is preferably 0.1 to 10% by mass, more preferably 0.2 to 10% by mass, and still more preferably 0.5 to 8% by mass based on 100% by mass of the detergent composition. is. When the content of the lubricant is within the above range, it is possible to improve the ease of replacement while maintaining the detergency.

(Surfactant)
Surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and the like.
Examples of anionic active agents include higher fatty acid alkali salts (alpha sulfo fatty acid methyl ester sodium, etc.), alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, sulfosuccinate salts, and the like. Examples of cationic activators include higher amine halides, alkylpyridinium halides, quaternary ammonium salts, and the like. Examples of nonionic active agents include polyethylene glycol alkyl ethers, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, pentaerythritol fatty acid esters (pentaerythritol tetrastearate, etc.), fatty acid monoglycerides, and the like. An amino acid etc. can be illustrated as an amphoteric surfactant.
Surfactants may be used alone or in combination of two or more.

The content of the surfactant is preferably 0.1 to 10% by mass, more preferably 0.2 to 10% by mass, and still more preferably 0.5 to 8% by mass based on 100% by mass of the detergent composition. % by mass. When the content of the surfactant is within the above range, it is possible to improve the ease of replacement while maintaining the detergency.

(Antioxidant)
Antioxidants include phosphorus antioxidants, phenolic antioxidants and the like, but are not particularly limited to these. Specific examples of phosphorus antioxidants include tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, 2,2' -methylenebis(4,6-di-t-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphite and the like. Specific examples of phenolic antioxidants include pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl -4-hydroxyphenyl)propionate, 4,4'-butylidenebis(6-t-butyl-m-cresol) and the like.
Antioxidants may be used singly or in combination of two or more.

The content of the antioxidant is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, and still more preferably 0.1 to 2% by mass relative to 100% by mass of the cleaning composition. % by mass. When the content of the antioxidant is within the above range, deterioration of the resin can be suppressed, and the decomposition product of the antioxidant itself can exert an inhibitory effect on other additives (lubricants, etc.). It is preferable because it is small.

(Inorganic filler)
In this specification, the term "inorganic filler" means an inorganic compound other than the inorganic foaming agent described below, and includes both natural products and artificially synthesized products. Specific examples of inorganic compounds include talc, mica, wollastonite, xonotlite, kaolin clay, montmorillonite, bentonite, sepiolite, imogolite, sericite, lawsonite, smectite, calcium sulfate fibers, calcium carbonate, magnesium carbonate, titanium oxide, and water. Examples include aluminum oxide, magnesium hydroxide, zeolite, diatomaceous earth, glass powder, glass spheres, glass fibers, shirasu balloons, and the like.

(Inorganic foaming agent)
As used herein, an inorganic foaming agent refers to an inorganic compound that is decomposed by heating to foam, that is, generate gas. Specific examples of inorganic foaming agents include inorganic physical foaming agents such as water, hydrogen carbonates such as sodium hydrogen carbonate and ammonium hydrogen carbonate, carbonates such as sodium carbonate and ammonium carbonate, nitrites such as ammonium nitrite, and borohydrides. Hydrides such as sodium, azide compounds such as calcium azide, light metals such as magnesium and aluminum, combinations of sodium bicarbonate and acids, combinations of hydrogen peroxide and yeast, combinations of aluminum powder and acids, and the like. Inorganic chemical blowing agents are mentioned.

(ultra-high molecular weight resin)
In this specification, the ultra high molecular weight resin is a polymer having a molecular weight of 1,000,000 or more, and examples thereof include ethylene-based ultra-high polymers, styrene-acrylonitrile-based ultra-high polymers, and methyl methacrylate-based ultra-high polymers. Among them, ethylene-based ultra-high polymers are preferred. Although the upper limit of the molecular weight is not particularly limited, it is practically preferably 10,000,000 or less.
In addition, the ultrahigh molecular weight resin may be a homopolymer or a copolymer, and in the case of a copolymer, the content of the main component (eg, ethylene, styrene-acrylonitrile copolymer, methyl methacrylate, etc.) must be 50% by mass or more. .
From the viewpoint of detergency and easy replacement, the content of the ultrahigh molecular weight resin is preferably 0.1% by mass or more and 10% by mass or less with respect to 100% by mass of the cleaning composition, and 0.2% by mass. % or more and 7 mass % or less, and more preferably 0.3 mass % or more and 5 mass % or less.
The super high molecular weight polyethylene (A) and the thermoplastic resin (B) do not include the super high molecular weight resin as the additive having the scrubbing effect.

Since the cleaning agent of the present embodiment is easy to replace, the content of additives having a scrubbing effect, such as the inorganic filler, inorganic foaming agent, and ultrahigh molecular weight resin, is preferably 10% by mass or less. It is more preferably 5% by mass or less, more preferably 5% by mass or less.
Although the effect of the additive having a scrubbing effect on the replaceability is not necessarily clear, it is considered as follows. In other words, additives with a scrubbing effect, such as inorganic fillers, inorganic foaming agents, and ultra-high molecular weight resins, improve the detergency, but when the flow path inside the mold or die is complicated, such as extrusion molding and injection molding Because it tends to stay in the molding machine, it is difficult to discharge, and it is considered that the replaceability is hindered.

[[Form of detergent for molding machine]]
The shape of the cleaning agent of the present embodiment is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include cylindrical, spherical, flake, and powder shapes.

[[Manufacturing method of detergent]]
The method for producing the detergent composition of the present embodiment is not particularly limited. For example, after premixing the above components in a mixer, the mixture is kneaded and extruded by an extruder such as a twin-screw extruder, and pelletized. can do.

[[Using cleaning agents for molding machines]]
The molding machine cleaning agent of the present embodiment can be used for any molding machine (resin molding machine) without any particular limitation.
Specific examples of molding machines include injection molding machines and extrusion molding machines.

[Washing method of molding machine]
The molding machine cleaning method of the present embodiment uses the molding machine cleaning agent described above. The method for cleaning a molding machine according to the present embodiment may include a step of retaining the cleaning agent for a molding machine described above in the molding machine.
Specific examples of the molding machine include those described above.
The method for cleaning a molding machine according to the present embodiment not only enables efficient discharge of the material molded before cleaning, but also fills the molding machine with a detergent composition when the molding machine is stopped after cleaning. Even if the material that has been molded before washing remains in the molding machine due to insufficient washing, the remaining material can be prevented from thermally deteriorating.

EXAMPLES The present embodiment will be described in more detail below with examples and comparative examples. The present embodiment is not limited to the following examples as long as the gist thereof is not exceeded.

Components used in Examples and Comparative Examples are as follows.
<Ultra-high molecular weight polyethylene (A)>
(A-1) Ultra-high molecular weight polyethylene homopolymer (weight average molecular weight: 500,000, intrinsic viscosity: 5 dL/g, average particle size: 100 μm)
(A-2) Ultra-high molecular weight polyethylene homopolymer (weight average molecular weight: 1,000,000, intrinsic viscosity: 7 dL/g, average particle size: 110 μm)
(A-3) Ultra-high molecular weight polyethylene homopolymer (weight average molecular weight: 3 million, intrinsic viscosity: 18 dL/g, average particle size: 100 μm)
(A-4) Ultra-high molecular weight polyethylene homopolymer (weight average molecular weight: 4.5 million, intrinsic viscosity: 20 dL/g, average particle size: 110 μm)
(A-5) Ultra-high molecular weight polyethylene homopolymer (weight average molecular weight: 4.2 million, intrinsic viscosity: 20 dL/g, average particle size: 30 μm)
The weight-average molecular weight of the ultra-high molecular weight polyethylene (A) was measured using ultra-high temperature GPC (manufactured by Senshu Scientific Co., Ltd.), using 1-chloronaphthalene as an eluent and polystyrene as a standard substance, at a column temperature of 210 ° C. It was measured. The average particle size of the ultra-high molecular weight polyethylene (A) powder is a value measured according to JIS K0069.

<Thermoplastic resin (B)>
(B-1) High-density polyethylene (weight average molecular weight: 300,000, density: 0.957 g/cm ³ , MFR: 0.30 g/10 minutes, conditions: 190°C, 2.16 kg)
(B-2) High-density polyethylene (weight average molecular weight: 200,000, density 0.963 g/cm ³ , MFR: 1.35 g/10 min, conditions: 190°C, 2.16 kg)
(B-3) High density polyethylene (weight average molecular weight: 80,000, density 0.961 g/cm ³ , MFR: 40 g/10 min, conditions: 190°C, 2.16 kg)
(B-4) Low-density polyethylene (weight average molecular weight: 100,000, density: 0.921 g/cm ³ , MFR: 2.0 g/10 minutes, conditions: 190°C, 2.16 kg)
(B-5) Polypropylene (SunAllomer PB170A manufactured by SunAllomer Co., Ltd., MFR: 0.35 g/10 minutes, conditions: 230° C., 2.16 kg)
(B-6) Styrene-acrylonitrile copolymer (Stylac AS783 manufactured by Asahi Kasei Corporation, MFR: 10 g/10 min, conditions: 220° C., 10 kg)

<Aliphatic hydrocarbon compound (C)>
(C-1) Mineral oil (weight average molecular weight: 500, kinematic viscosity 95 mm ² /sec)
(C-2) Polyethylene wax (High wax 220P manufactured by Mitsui Chemicals, Inc., weight average molecular weight: 2000, density: 0.920 g/cm ³ , softening point: 113°C)
(C-3) Polypropylene wax (Viscol 550-P manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight: 15000, softening point: 152° C.)

<Organic acid metal salt (D)>
(D-1) zinc stearate

<Other additives>
(lubricant, surfactant)
(E-1) Ethylene bis stearamide (NOF CORPORATION Alflow H-50F, melting point: 145° C.)
(E-2) Alpha sulfo fatty acid methyl ester sodium (E-3) Pentaerythritol tetrastearate (E-4) Condensed ricinoleic acid tetraglycerol (E-5) Glass fiber (antioxidant)
(F-1) phosphorus antioxidant (Irgafos168 manufactured by BASF, tris (2,4-di-t-butylphenyl) phosphite)
(F-2) Phenolic antioxidant (Irganox 1010 manufactured by BASF, pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate])

Methods for evaluating the detergents obtained in Examples and Comparative Examples are as follows.

<Morphology of detergent composition, average particle size of ultra-high molecular weight polyethylene (A)>
For the examples and comparative examples containing ultra-high molecular weight polyethylene (A) and thermoplastic resin (B), the cross section of the obtained detergent composition pellets was exposed with a microtome and measured with a digital microscope (VHX-manufactured by Keyence Corporation). 5000), the cross section was photographed at a magnification of 100 to 500, and the morphology of the detergent composition was observed. When the dispersed phase (islands) was not confirmed with a digital microscope, observation was performed using a transmission electron microscope (H-7600 manufactured by Hitachi, Ltd.). Pellets of the detergent composition are embedded and molded in an epoxy resin, and ultra-thin sections are obtained using a cryo-ultramicrotome, and electron beam staining is performed with vapor of ruthenium tetroxide to prepare samples at a magnification of 1,000 to 10,000. The morphology of the detergent composition was observed at .
If no dispersed phase (island) with a recognizable size (dispersion diameter of 0.5 μm or more) is observed, or if phase separation is not observed, the ultra-high molecular weight polyethylene (A) is compatible with the detergent composition. I decided that I did.
When a sea-island structure in which the sea portion and the island portion are phase-separated is observed, that is, when the ultrahigh molecular weight polyethylene (A) is dispersed in the detergent composition, it is observed using image analysis software (ImageJ). The sea-island structure of the image was binarized, and the areas of 50 or more island-like domains in the binarized image were calculated. The average value of the equivalent circle diameters obtained from the formula (equivalent circle diameter=2×(area/π) ^0.5 ) was taken as the average particle diameter, and evaluation was made according to the following criteria. It was confirmed that the observed island-like domains were only due to ultra-high molecular weight polyethylene (A).
-Evaluation criteria-
Good: The average particle size is 90 μm or less.
x: The average particle size is more than 90 μm.

<Detergency evaluation>
(color change performance)
A blue-colored low-density polyethylene (Suntec M1920, manufactured by Asahi Kasei Corporation) is used as a coloring masterbatch, and 10% by mass of the colored masterbatch and 90% by mass of high-density polyethylene (Suntec B871, manufactured by Asahi Kasei Corporation) are mixed and subjected to small extrusion. 0.5 kg of the mixture was put into the machine (Plasticorder manufactured by Brabender), and the screw was rotated to discharge the resin mixture from the die so that the inside of the molding machine was coated with imitation dirt.
After that, 1 kg of the detergent compositions obtained in Examples and Comparative Examples were put into the molding machine, and washed by screw rotation under conditions of a cylinder temperature of 200°C and a die temperature of 200°C. While visually observing the color tone of the purge debris discharged from the die, the purge debris was discharged until the cleaning was completed. The amount (kg) of discharged purge debris was measured with a balance, and the washability (color change performance) was evaluated according to the following evaluation criteria.
The washing was completed when the color tone of the purge debris discharged from the die after washing was cooled to room temperature and solidified, changing from blue to the color of the detergent composition.
-Evaluation criteria-
⊚ (excellent): The amount of purge debris discharged is less than 0.20 kg.
◯ (Good): The amount of discharged purge debris is 0.20 kg or more and less than 0.30 kg.
x (defective): The amount of discharged purge debris is 0.30 kg or more.

(Burning removal performance)
100 g of polyethylene-based resin was charged into a small extruder (Plasticorder manufactured by Brabender) heated to 280° C., the screw was rotated, and the resin was discharged from the nozzle to adhere the resin inside the small extruder. After that, the mixture was retained at the same temperature for 4 hours, and the burn of the polyethylene-based resin remaining adhered to the inside of the extruder was produced. After that, 100 g of the detergent compositions obtained in Examples and Comparative Examples were put into the extruder to wash the inside.
After that, the screw was pulled out, the remaining amount of scorch adhering to the screw surface was measured, and the washability (scorch removal performance) was evaluated according to the following evaluation criteria.
-Evaluation criteria-
⊚ (excellent): scorching is completely removed from the screw.
◯ (Good): Burn marks remain on the screw, and the remaining area is less than 30% of the total surface area of the screw.
x (defective): scorching remains on the screw, and the remaining area is 30% or more of the total surface area of the screw.

<Replacement evaluation>
After the above <cleanability evaluation> (color change performance), 1 kg of high-density polyethylene (Suntech B871 manufactured by Asahi Kasei Corporation) was put into a small extruder (Plasticorder manufactured by Brabender), and the cylinder temperature was 200 ° C. and the die temperature. The replacement was carried out by rotating the screw at 200° C., and while visually observing the color tone of the appearance of the molten resin discharged from the die, the purge debris was discharged until the replacement was completed. The amount (kg) of discharged purge debris was measured with a balance, and the replaceability was evaluated according to the following evaluation criteria.
The replacement was completed when the appearance color tone of the molten purge debris discharged from the die during the replacement changed from the color of the cleaning composition to colorless and transparent.
-Evaluation criteria-
⊚ (excellent): The amount of purge debris discharged is less than 0.20 kg.
◯ (Good): The amount of discharged purge debris is 0.20 kg or more and less than 0.30 kg.
x (defective): The amount of discharged purge debris is 0.30 kg or more.

[Examples 1 to 11, Comparative Examples 1 to 6]
<Preparation of detergent composition>
A composition containing each component in the ratio shown in Table 1 was premixed for 5 minutes using a tumbler blender, and the resulting mixture was kneaded with a twin-screw extruder (TEM26SX manufactured by Toshiba Machine Co., Ltd.). The kneading conditions were a cylinder temperature of 260°C and an extrusion rate of 10 kg/hour. The melt-kneaded product thus obtained was extruded into a strand, cooled with water, and then cut with a strand cutter to obtain a detergent composition in the form of pellets.
Table 1 shows the evaluation results of each example and comparative example.

From the above results, it can be seen that the detergent compositions obtained in Examples 1 to 11 have good detergency (color change performance and burn removal performance) and easy replacement.
On the other hand, from the above results, it was found that the detergent composition obtained in Comparative Example 1, which did not contain ultra-high molecular weight polyethylene (A), had poor detergency and was not suitable for removing burns. In the detergent composition obtained in Comparative Example 2, the compatibility between the ultra-high molecular weight polyethylene (A) and the high-density polyethylene of the thermoplastic resin (B) did not progress and the average particle size in the composition was large. Therefore, it was found that it tends to stay in the molding machine and has poor replaceability. It was found that the detergent composition obtained in Comparative Example 3 did not contain the thermoplastic resin (B), and thus had low fluidity and poor substitutability. In Comparative Example 4, since the motor load of the twin-screw extruder was increased, each component could not be kneaded, and the detergent composition could not be produced. The cleaning agent composition obtained in Comparative Example 5 had poor replacement properties due to the large average particle size in the composition of the ultra-high molecular weight polyethylene (A). sufficient performance was not obtained. The cleaning agent composition obtained in Comparative Example 6 contains glass fibers and therefore has excellent cleaning properties. Substitutability was poor due to the fact that it tends to remain in the

The cleaning agent for molding machines of the present invention not only exhibits excellent cleaning performance (removal of color change, burn marks, etc.), but also has excellent replaceability. It is useful as a cleaning agent for molding machines.

Claims (9)

A molding machine cleaning agent comprising an ultra-high molecular weight polyethylene (A) and a thermoplastic resin (B) other than the ultra-high molecular weight polyethylene (A), wherein the ultra-high molecular weight polyethylene (A) is the molding machine cleaning agent. A detergent for a molding machine, characterized in that it is compatible with or dispersed in the agent, and when dispersed, the ultra-high molecular weight polyethylene (A) has an average particle size of 90 μm or less. The cleaning agent for a molding machine according to claim 1, further comprising an aliphatic hydrocarbon compound (C) having a weight average molecular weight of 200 or more and 20,000 or less. The cleaning agent for a molding machine according to claim 2, wherein the content of the aliphatic hydrocarbon compound (C) is 0.01% by mass or more and 20% by mass or less. The cleaning agent for a molding machine according to any one of claims 1 to 3, wherein the thermoplastic resin (B) contains at least one type of polyolefin resin. The cleaning agent for molding machines according to any one of claims 1 to 3, wherein the content of the ultra-high molecular weight polyethylene (A) is 20% by mass or more and 80% by mass or less. The cleaning agent for a molding machine according to any one of claims 1 to 3, wherein the ultra-high molecular weight polyethylene (A) has a weight average molecular weight of 400,000 or more and 1,000,000 or less. The cleaning agent for a molding machine according to any one of claims 1 to 3, further comprising an organic acid metal salt (D). A method for cleaning a molding machine, comprising using the cleaning agent for a molding machine according to any one of claims 1 to 3. Use of the cleaning agent for molding machines according to any one of claims 1 to 3 in cleaning molding machines.