Cleaning agent for resin processing machine, method for producing cleaning agent for resin processing machine, and method for cleaning resin processing machine

Abstract

The objective of the present invention is to provide a cleaning agent for a resin processing machine that has such excellent cleaning performance, easy replaceability (non-remaining property) and pellet feeding property that the resin remaining in a resin flow passage of a melt molding machine can be quickly cleaned and discharged and the residual of the cleaning agent for a resin processing machine itself can be easily replaced with the subsequent molding material.　The present invention is characterized by containing at least a thermoplastic resin (A), a first filler (B) comprising glass fibers, and a second filler (C), in which the weight average fiber length of the first filler (B) is 650-1600 μm.

Description

Cleaning Agent for Resin Processing Machine, Method for Producing Cleaning Agent for Resin Processing Machine, and Method for Cleaning Resin Processing Machine

[0001] The present invention relates to a cleaning agent for a resin processing machine, a method for producing the same, and a method for cleaning a resin processing machine.

[0002] Generally, resin molding processing machines such as extrusion molding machines and injection molding machines are used for operations such as coloring, mixing, and molding of resins. And in these resin processing machines, at the end of a predetermined operation, in addition to additives such as dyes and pigments contained in the resin itself or the molding material, degradation products (for example, thermal decomposition products, burns, carbides, etc.) generated from the resin may remain in the resin processing machine. If this residue is left unattended, there is a risk that the residue will mix into the molded product during subsequent resin molding processing, causing poor product appearance. In particular, when molding transparent resins, even the mixing of minute carbides or the like can be easily visually recognized, resulting in poor appearance of the molded product and an increase in the occurrence rate of defective molded products. Therefore, it is desired to completely remove the residues generated during resin molding processing from the resin processing machine.

[0003] Conventionally, as methods for removing residues from a resin processing machine, (1) a method of manually disassembling and cleaning the resin processing machine, (2) a method of filling the resin processing machine with the molding material to be used for the next molding without stopping the resin processing machine, thereby gradually discharging the residues, (3) a method using a cleaning agent, etc. have been used.

[0004] However, the method (1) above has a problem that it is not efficient because it is necessary to stop the resin processing machine, and in addition, since the removal work is physically performed manually, it is easy to damage the resin processing machine. Also, the method (2) above often requires a large amount of molding material to remove the residues, takes time to complete the work, and has a problem of generating a large amount of waste. Therefore, in recent years, the method (3) using a cleaning agent is preferably used because it has excellent cleaning power for removing residues in the resin processing machine.

[0005] When cleaning a resin processing machine using a cleaning agent, after cleaning with the cleaning agent and before proceeding to the next molding process, the remaining cleaning agent is usually replaced by the next molding material. Therefore, the cleaning agent used must have high cleaning power against the molding material used in the previous molding process and be easily replaceable by the molding material used in the next molding process (ease of replacement).

[0006] As an example of a cleaning agent that improves cleaning performance and ease of substitution, a technique has been disclosed in which a cleaning agent comprising a styrene-based resin and a specific graft polymer is further contained in the cleaning agent, and glass fibers or glass particles are included in the cleaning agent (Patent Document 1). Another technique has also been disclosed in which a cleaning agent resin composition containing 0.5 to 20 parts by mass of a fluorinated polymer and / or an acid or acid anhydride modified polymer is included in 100 parts by mass of a mixture containing a thermoplastic resin and wollastonite (Patent Document 2).

[0007] However, in recent years, with the growing awareness of environmental issues such as resin recycling and reduction of materials used, there is a strong market demand to minimize resin loss during cleaning. Therefore, there is a need for the development of a superior cleaning agent composition that has excellent cleaning performance and is easily replaceable, resulting in minimal residue in the molding machine. In particular, while cleaning agent resin compositions containing inorganic fillers have high cleaning performance, they tend to remain in the molding machine, which has the drawback of potentially hindering transparency when the next molding material is a transparent resin.

[0008] Japanese Patent Publication No. 5-42547 Japanese Patent Publication No. 2004-107433

[0009] The present invention aims to provide a cleaning agent for resin processing machines that has excellent cleaning performance and easy replacement (non-residual) properties, in order to meet the recent market demand for resource conservation.

[0010] As a result of diligent research to solve the above problems, the inventors of the present invention discovered that by including a certain amount of glass fibers having a specific weight-average fiber length as a filler in a thermoplastic resin, it is possible to obtain excellent cleaning performance as well as excellent replaceability and pellet embedding properties, leading to the development of the present invention.

[0011] In other words, the present invention is as follows: [1] A cleaning agent for resin processing machines, comprising at least (A) a thermoplastic resin, (B) a first filler which is glass fiber, and (C) a second filler, wherein the weight-average fiber length of the (B) first filler is 650 to 1600 μm. [2] The cleaning agent for resin processing machines according to [1], comprising 25 to 140 parts by mass of the (B) first filler and 25 to 140 parts by mass of the (C) second filler per 100 parts by mass of the (A) thermoplastic resin. [3] The cleaning agent for resin processing machines according to [1] or [2], wherein the total content of the (B) first filler and the (C) second filler is 50 to 200 parts by mass per 100 parts by mass of the (A) thermoplastic resin. [4] A cleaning agent for resin processing machines according to any one of [1] to [3], characterized in that the mass ratio of the first filler (B) to the second filler (C) is 90 / 10 to 10 / 90. [5] A cleaning agent for resin processing machines according to any one of [1] to [4], characterized in that the second filler (C) is an inorganic filler other than glass fiber. [6] A cleaning agent for resin processing machines according to any one of [1] to [5], characterized in that the second filler (C) is calcium carbonate and / or talc. [7] A cleaning agent for resin processing machines according to any one of [1] to [6], characterized in that the thermoplastic resin (A) includes at least one selected from the group consisting of styrene resins, polyolefin resins and methacrylic acid resins. [8] A cleaning agent for resin processing machines according to any one of [1] to [7], characterized in that the thermoplastic resin (A) includes at least a styrene resin. [9] A cleaning agent for resin processing machines according to [8], characterized in that the styrene resin is a styrene-acrylonitrile copolymer.

[10] The cleaning agent for resin processing machines according to any one of [1] to [9], characterized in that the (A) thermoplastic resin contains a styrene resin and a polyolefin resin, and the mass ratio of the styrene resin to the polyolefin resin is 99 / 1 to 85 / 15.

[11] The cleaning agent for resin processing machines according to any one of [1] to

[10] , characterized in that the content ratio of fillers with a fiber length of 900 μm or more among the (B) first fillers is 10% by mass or more.

[12] The cleaning agent for a resin processing machine according to any one of [1] to

[11] , characterized in that, in an electron microscope image of the cleaning agent for the resin processing machine, the ratio of the area of ​​the second filler (C), which is equal to or greater than the average fiber diameter of the first filler (B), to the total area of ​​the second filler (C) observed is 5% or more.

[13] The cleaning agent for a resin processing machine according to any one of [1] to

[12] , characterized in that the ratio (Lw / Ln) of the weight-average fiber length (Lw) to the number-average fiber length (Ln) of the first filler (B) is 1.16 to 1.50.

[14] The cleaning agent for a resin processing machine according to any one of [1] to

[13] , characterized in that the average fiber diameter of the first filler (B) is 9 to 15 μm.

[15] A method for manufacturing a cleaning agent for a resin processing machine according to any one of [1] to

[14] , comprising a melt-kneading step of melt-kneading the (A) thermoplastic resin, the (B) first filler, and the (C) second filler, wherein the melt-kneading step comprises: step (1-1): melt-kneading the entire amount of the (A) thermoplastic resin and a portion of the (C) second filler, and step (1-2): adding the remainder of the (C) second filler and the entire amount of the (B) first filler to the melt-kneaded product obtained in step (1-1), and melt-kneading the mixture.

[16] A method for manufacturing a cleaning agent for resin processing machines according to [1] to

[14] , comprising a melt-kneading step of melt-kneading the (A) thermoplastic resin, the (B) first filler, and the (C) second filler, wherein the melt-kneading step comprises: step (1-1'): melt-kneading the entire amount of the (A) thermoplastic resin, and step (1-2'): adding the entire amount of the (B) first filler and the entire amount of the (C) second filler to the melt-kneaded product obtained in step (1-1'), and melt-kneading the mixture.

[17] A method for cleaning a resin processing machine with a cleaning agent for resin processing machines according to any one of [1] to

[14] .

[0012] According to the present invention, it is possible to reduce the amount of resin processing machine cleaning agent required for cleaning molding materials, reduce the amount of resin used in displacement injection operations, and provide a resin processing machine cleaning agent that is easily removed, with excellent cleaning performance and easy displacement (non-residual).

[0013] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"). It should be noted that the present invention is not limited to the embodiments described below, and can be implemented in various modifications within the scope of its gist.

[0014] [Cleaning agent for resin processing machines] The cleaning agent for resin processing machines according to this embodiment (hereinafter sometimes simply referred to as "cleaning agent") contains at least (A) a thermoplastic resin (hereinafter sometimes referred to as "component (A)"), (B) a first filler which is glass fiber (hereinafter sometimes referred to as "component (B)"), and (C) a second filler which is "component (C)", wherein the weight-average fiber length of component (B) is 650 to 1600 μm. The cleaning agent for resin processing machines according to this embodiment may consist only of components (A) to (C), or it may be a cleaning agent for resin processing machines which contains components (A) to (C) and other components.

[0015] Furthermore, in the resin processing machine cleaning agent according to this embodiment, the weight-average fiber length of component (B) is 650 to 1600 μm. By having the above configuration, the resin processing machine cleaning agent according to this embodiment can achieve not only excellent cleaning performance but also excellent replaceability. The reason will be explained later, but it is thought that the glass fibers with long fiber lengths (weight-average fiber length of 650 μm or more) are effective in improving cleaning performance.

[0016] <(A) Thermoplastic Resin> The (A) thermoplastic resin (hereinafter sometimes referred to as "component (A)") contained in the cleaning agent for resin processing machines according to this embodiment can be a wide range of resins used in injection molding, extrusion molding, etc. Specific examples of the (A) thermoplastic resin include styrene resins such as polystyrene, polyolefin resins (ethylene resins such as polyethylene, propylene resins such as polypropylene), and methacrylic acid ester resins such as polymethyl methacrylate. Among these, it is preferable to contain a styrene resin, a polyolefin resin, or a methacrylic resin, more preferably to contain at least a styrene resin, and even more preferably to contain both a styrene resin and a polyolefin resin.

[0017] The styrene-based resin refers to polystyrene, or a copolymer of styrene with one or more other monomers, having a styrene content of 50% by mass or more. Examples of other monomers copolymerized with styrene include acrylonitrile and butadiene. Specific examples of this styrene-based resin include polystyrene, styrene-acrylonitrile copolymer, and styrene-butadiene-acrylonitrile copolymer. Among these, styrene-acrylonitrile copolymer is preferred from the viewpoint of cleaning performance and non-residual properties in the molding machine, and in particular, styrene-acrylonitrile copolymer with an acrylonitrile content of 5% by mass or more and 50% by mass or less is preferred.

[0018] The aforementioned polyolefin resins include polyethylene resins, polypropylene resins, and others, and also include copolymer resins of ethylene and propylene with α-olefins. Among these, polypropylene resins containing polypropylene and propylene copolymers are preferred because they have excellent cleaning performance and do not leave residues inside the molding machine.

[0019] Furthermore, when the thermoplastic resin (A) contains the two types of resins described above, styrene-based resin and polyolefin-based resin, the mass ratio (styrene-based resin / polyolefin-based resin) is preferably 99 / 1 to 85 / 15, and more preferably 99 / 1 to 90 / 10, from the viewpoint of cleaning performance and / or ease of substitution. It is believed that this range suppresses the accumulation of cleaning agents for resin processing machines within the resin processing machine (however, the effects are not limited to this).

[0020] The molecular weight of the thermoplastic resin (A) is not particularly limited, but is preferably 200,000 to 300,000. The melt mass flow rate (MFR) of the thermoplastic resin (A) is preferably 0.5 to 30 g / 10 min, and more preferably 0.5 to 15 g / 10 min. If the MFR of the thermoplastic resin (A) is less than 0.5 g / 10 min, it is difficult to use under standard molding conditions, for example, at a molding temperature of 200 to 280°C, and if it exceeds 30 g / 10 min, it becomes difficult to obtain a sufficient cleaning effect. In this specification, MFR refers to the MFR value measured under conditions of 220°C and 10 kg in accordance with ISO 1133.

[0021] <(B) First Filler (Glass Fiber)> The first filler, which is (B) glass fiber contained in the cleaning agent for resin processing machines according to this embodiment, has no restrictions on its shape, and known glass fibers can be used. Furthermore, it is preferable that the glass fiber is glass fiber that has been treated with a surface treatment that matches the (A) component used, for example, with epoxy resin, urethane resin, etc., as a coupling agent or sizing agent such as silane-based or titanate-based.

[0022] Here, the content of (B) glass fibers (first filler) is preferably 25 to 140 parts by mass, more preferably 50 to 130 parts by mass, and even more preferably 50 to 125 parts by mass, per 100 parts by mass of (A) thermoplastic resin. If the content of (B) glass fibers is less than 25 parts by mass per 100 parts by mass of component (A), it is difficult to obtain the effect of adding glass fibers, and if it exceeds 140 parts by mass per 100 parts by mass of component (A), it tends to cause adverse effects such as cylinder friction of the molding machine.

[0023] Furthermore, the average fiber diameter of the glass fiber (first filler) (B) is preferably 9 to 15 μm.

[0024] Furthermore, the glass fibers (first filler) (B) contained in the resin processing machine cleaning agent according to this embodiment can achieve a balance between cleaning performance and burn removal by setting the weight-average fiber length within a specific range. Specifically, the weight-average fiber length of the glass fibers in the resin processing machine cleaning agent must be 650 to 1600 μm, and preferably 700 to 1300 μm. By setting the weight-average fiber length of the glass fibers (B) to 650 μm or more, the cleaning agent for resin processing machines can be provided with excellent cleaning performance, and by setting the weight-average fiber length of the glass fibers (B) to 1600 μm or less, good replaceability can be maintained, and deterioration of ease of manufacture (manufacturability) can be suppressed. Regarding the weight-average fiber length of the glass fibers (B) mentioned above, for example, pellets of cleaning agent for resin processing machines can be heated in an electric furnace at 600°C for one hour to incinerate them, the weight of the pellets can be measured, and then 200 glass fibers can be arbitrarily selected from the pellets. The weight-average fiber length can then be calculated by measuring the fiber length using a stereomicroscope (for example, Nikon's "SMZ1270").

[0025] Furthermore, it is preferable that the (B) glass fibers (first filler) have a content ratio of glass fibers with a fiber length of 900 μm or more of the total (B) glass fibers of 10% by mass or more. This is because a higher content ratio of glass fibers with a fiber length of 900 μm or more of 10% by mass or more can be obtained. From a similar viewpoint, it is more preferable that the content ratio of glass fibers with a fiber length of 900 μm or more of 15% by mass or more of the total glass fibers. Regarding the content ratio of glass fibers with a fiber length of 900 μm or more, for example, pellets of cleaning agent for resin processing machines are heated in an electric furnace at 600°C for 1 hour to incinerate them, and the weight of the pellets is measured. Then, 200 glass fibers are arbitrarily selected from the pellets, and their fiber lengths are measured using a stereomicroscope (for example, Nikon's "SMZ1270"). The proportion of glass fibers with a fiber length of 900 μm or more among the selected 200 glass fibers is calculated as the content ratio of glass fibers with a fiber length of 900 μm or more.

[0026] Furthermore, the glass fibers (first filler) (B) preferably have a ratio (Lw / Ln) of weight-average fiber length (Lw) to number-average fiber length (Ln) of 1.16 to 1.50, from the viewpoint of achieving a higher level of both cleaning performance and easy replacement. When Lw / Ln is 1.16 or higher, better cleaning performance can be obtained without degrading easy replacement, and when Lw / Ln is 1.50 or lower, better easy replacement can be obtained without degrading cleaning performance. The number-average fiber length of the glass fibers (B) can be calculated, for example, by heating pellets of cleaning agent for resin processing machines in an electric furnace at 600°C for 1 hour to incinerate them, then arbitrarily selecting 200 glass fibers from the pellets and measuring their fiber lengths using a stereomicroscope (for example, Nikon's "SMZ1270").

[0027] Furthermore, it is preferable that the (B) glass fibers (first filler) have an aspect ratio (L / D) of 55 to 80 between the weight-average fiber length (L) and the number-average fiber diameter (D). This is to achieve both cleaning performance and the surface appearance of the pellets. The number-average fiber diameter of the (B) glass fibers can be calculated, for example, by heating the pellets of the cleaning agent for resin processing machines in an electric furnace at 600°C for one hour to incinerate them, then arbitrarily selecting 200 glass fibers from the pellets and measuring their fiber diameters using a scanning electron microscope (SEM).

[0028] Here, the means for controlling the parameters of (B) glass fibers (first filler), such as the weight-average fiber length, the content ratio of glass fibers with a fiber length of 900 μm or more, the number-average fiber length, and the ratio of weight-average fiber length (Lw) to number-average fiber length (Ln) (Lw / Ln), to a specific range are not particularly limited. For example, the above parameters can be adjusted and controlled to a specific range by adjusting the type of manufacturing machine (extruder) used in the production of cleaning agents for resin processing machines, the temperature during melt kneading, the screw rotation speed, and the screw configuration. For example, when adjusting the screw rotation speed, the lower the screw rotation speed, the longer the glass fiber length tends to be. When adjusting the screw configuration, the fewer the number of blocks consisting of multiple screw elements with high kneading effect called kneading discs (hereinafter referred to as kneading blocks), the longer the glass fiber length tends to be. The supply position of component (B) can also be controlled, and delaying the supply timing tends to increase the glass fiber length. <(C) Second filler>

[0029] The (C) second filler contained in the cleaning agent for resin processing machines according to this embodiment may be any filler other than glass fiber, and can be either an inorganic or organic filler. Examples include talc, mica, wollastonite, xonotlite, kaolin clay, montmorillonite, bentonite, sepiolite, imogolite, sericite, lawsonite, smectite, calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, magnesium hydroxide, zeolite, diatomaceous earth, glass powder, glass spheres, shirasu balloons, cellulose fibers, etc. Among these, the (C) second filler is preferably an inorganic filler, preferably calcium carbonate or talc, and preferably calcium carbonate.

[0030] Furthermore, the shape of the second filler (C) is not particularly limited and may be any shape. The inorganic compound may be calcined or have been subjected to surface hydrophobic treatment with a silane coupling agent, titanate coupling agent, etc.

[0031] Furthermore, the content of the second filler (C) is preferably 25 to 140 parts by mass, more preferably 35 to 125 parts by mass, and even more preferably 50 to 60 parts by mass, per 100 parts by mass of the thermoplastic resin (A). If the content of the second filler is less than 25 parts by mass per 100 parts by mass of component (A), it is difficult to obtain the effect of adding the second filler, and it becomes difficult to set the first filler (B) to a specific weight-average fiber length and / or fiber length ratio. Also, if the content of the second filler exceeds 140 parts by mass per 100 parts by mass of component (A), it tends to cause adverse effects such as cylinder friction of the molding machine.

[0032] Furthermore, the total amount of component (B) and component (C) blended is 50 to 200 parts by mass, preferably 100 to 200 parts by mass, per 100 parts by mass of component (A), from the viewpoint of achieving both cleaning performance and easy substitution. In addition, the content ratio ((B) / (C)) is 80 / 20 to 20 / 80 by mass, preferably 70 / 30 to 30 / 70, and more preferably 60 / 40 to 40 / 60. If the mass ratio of component (B) and component (C) is outside the above range, for example, if there is a large amount of component (C) and a small amount of component (B), the cleaning performance may decrease.

[0033] Furthermore, in the observed image of the resin processing machine cleaning agent according to this embodiment when observed with an electron microscope, the ratio of the area of ​​component (C) which is equal to or greater than the average fiber diameter of component (B) to the total area of ​​the observed second filler (C) is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. Regarding the area of ​​component (C) in the electron microscope image of the resin processing machine cleaning agent, for example, it is possible to calculate the ratio of the total area of ​​component (C) observed and the area of ​​component (C) which is equal to or greater than the average fiber diameter of component (B) using an SEM and image processing software (e.g., Adobe Photoshop Elements 2022) on pellets of the resin processing machine cleaning agent. By setting the ratio of the area of ​​component (C) which is equal to or greater than the average fiber diameter of component (B) to 5% or more, superior cleaning performance can be obtained (however, the effects are not limited to this). The means for controlling the ratio of the area of ​​component (C) to a specific range are not particularly limited. For example, the parameters mentioned above can be adjusted and controlled to a specific range by adjusting the type of manufacturing machine (extruder) used in the production of cleaning agents for resin processing machines, the temperature during melting and kneading, the screw rotation speed, and the screw configuration. When adjusting the screw rotation speed, the particle size of component (C) tends to increase as the screw rotation speed decreases. When adjusting the screw configuration, the particle size of component (C) tends to increase as the number of consecutive blocks of highly kneading screw elements called kneading discs (hereinafter referred to as kneading blocks) decreases. The supply position of component (C) can also be controlled, and delaying the supply timing tends to increase the particle size.

[0034] <Other Components> The cleaning agent for resin processing machines of this embodiment may contain components other than those listed above (A) to (C), as long as they do not impair the effects of the present invention. Other components may include thermoplastic resins other than component (A), antioxidants, light stabilizers, UV absorbers and other stabilizers, lubricants, surfactants, antiblocking agents, antistatic agents, antifogging agents, nucleating agents, crosslinking promoters, crosslinking inhibitors, colorants, aliphatic hydrocarbon compounds, inorganic foaming agents, ultra-high molecular weight resins, etc., as appropriate, for the purpose of providing each with an effective function.

[0035] (Aliphatic hydrocarbon compounds) The cleaning agent for resin processing machines of this embodiment may contain aliphatic hydrocarbon compounds. The aliphatic hydrocarbon compound is not particularly limited as long as its weight-average molecular weight is 200 or more and 50,000 or less, and examples include mineral oil, paraffin wax, olefin wax, etc.

[0036] The aforementioned mineral oil is an oil obtained by refining petroleum, and is a saturated hydrocarbon oil that also includes naphthenes, isoparaffins, etc., and is also called mineral oil, lubricating oil, or liquid paraffin. Mineral oils with a wide viscosity range can be used; for example, in the case of liquid paraffin, the kinematic viscosity measured according to JIS K2283 is 50 to 500 mmHg. ２ You may also use a paraffin wax with a viscosity of 30 to 2000 (seconds) as measured by the Redwood method (Japan Oil Chemists' Association Standard Method for Analysis of Oils and Fats 2.2.10.4-1996). The paraffin wax mentioned above is a paraffin compound that is solid at room temperature obtained by refining petroleum, and is commonly used if it has a melting point of 40 to 80°C.

[0037] Furthermore, the olefin-based wax can be low-molecular-weight polyolefins, and is not particularly limited; however, general low-density or high-density polyethylene, polypropylene, etc., are commonly used. Waxes with a weight-average molecular weight of approximately 800 to 50,000 and a dropping point of 80 to 180°C tend to be the most effective.

[0038] The content of the aliphatic hydrocarbon compound is preferably 0.01 parts by mass to 20 parts by mass, more preferably 0.05 to 15 parts by mass, and even more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the cleaning agent for resin processing machines of this embodiment. When the content of the aliphatic hydrocarbon compound is within the above range, it is possible to improve the ease of substitution while maintaining cleaning performance. In addition, by adding the aliphatic hydrocarbon compound, the motor load (torque) of the kneader, such as a twin-screw extruder, is reduced when kneading the cleaning agent for resin processing machines, making it easier to manufacture the cleaning agent for resin processing machines.

[0039] (Lubricant) Examples of the lubricant include, but are not limited to, organic acids, organic acid metal salts, organic acid amides, organic acid esters and other organic acid derivatives, various ester waxes, and fluororesins. The lubricant shall not include the aliphatic hydrocarbon compounds mentioned above. The lubricant may be a single type or a combination of two or more types.

[0040] The organic acids are preferably saturated fatty acids having 9 to 28 carbon atoms, unsaturated fatty acids having 9 to 28 carbon atoms, and benzoic acid. They may also have a hydroxyl group in part of the chain. In particular, stearic acid, 12-hydroxystearic acid, palmitic acid, myristic acid, and lauric acid are more preferred from the viewpoint of availability and heat resistance. Mixed fatty acids with different alkyl chains are also acceptable. The carbon number being within the above range is preferable because it does not cause problems with gas generation or odor, and it is readily available and functions well as a lubricant at interfaces.

[0041] The metal in the aforementioned organic acid metal salt is not particularly limited, but examples include sodium, potassium, lithium, cesium, magnesium, calcium, aluminum, zinc, iron, cobalt, and barium. Among these, lithium, calcium, barium, zinc, or aluminum are preferred as they exhibit the most effective lubricating effect. Furthermore, aluminum and zinc are more preferred because they have low polarity and readily exhibit external lubricity through bleed-out from thermoplastic resins. Zinc is particularly preferred. The hydrocarbon portion in the aforementioned organic acid metal salt is preferably saturated fatty acid having 9 to 28 carbon atoms, unsaturated fatty acid having 9 to 28 carbon atoms, or benzoic acid, as with the organic acid described above. From the viewpoint of availability and heat resistance, stearic acid, 12-hydroxystearic acid, palmitic acid, myristic acid, and lauric acid are more preferred.

[0042] Examples of the organic acid amide include saturated fatty acid amides, unsaturated fatty acid amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, etc. having 9 to 28 carbon atoms. Among them, amides of fatty acids having 12 to 18 carbon atoms such as lauric acid, myristic acid, palmitic acid, stearic acid, etc., amides of unsaturated fatty acids such as erucic acid, and saturated fatty acid bisamides such as ethylene bisstearic acid amide are preferable from the viewpoints of easy availability and the effect as a lubricant, and more preferably saturated fatty acid bisamides such as ethylene bisstearic acid amide.

[0043] Examples of the organic acid ester and ester wax include saturated fatty acid esters, unsaturated fatty acid esters, polyol esters such as medium-chain fatty acid triglycerides, hydrogenated oils, etc. having 9 to 28 carbon atoms. From the viewpoints of easy availability and the effect as a lubricant, stearyl stearate, glycerin fatty acid ester monoglyceride, etc. are preferable.

[0044] Examples of the fluororesin include PTFE, PFA, PVDF, PVDF-based copolymers, ETFE, PFE, etc., and an effect of suppressing resin adhesion to a metal surface can be expected. As the shape, various shapes such as pellet shape, powder shape, etc. can be used, but a powder shape is particularly preferable for uniform dispersion during processing. The average particle size is not particularly limited, but is preferably 1,000 μm or less. From the viewpoint of cleaning performance, the lubricant preferably has a surface tension of 32 mN / m or less. For example, the surface tension of zinc stearate is 24 mN / m, the surface tension of aluminum stearate is 25 mN / m, etc. Also, the lubricant preferably has a melting point or softening point of 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher.

[0045] The content of the lubricant is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass with respect to 100 parts by mass of the cleaning agent for resin processing machines of the present embodiment. When the content of the lubricant is within the above range, easy replaceability can be enhanced while maintaining cleaning performance.

[0046] (Surfactants) Examples of surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. Examples of anionic surfactants include alkali salts of higher fatty acids (such as sodium alpha-sulfo fatty acid methyl ester), alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, and sulfosuccinate esters. Examples of cationic surfactants include higher amine halates, alkylpyridinium halides, and quaternary ammonium salts. Examples of nonionic surfactants include polyoxyethylene glycol, polyethylene glycol alkyl ether, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, pentaerythritol fatty acid ester (such as pentaerythritol tetrastearate), and fatty acid monoglycerides. Examples of amphoteric surfactants include amino acids. The surfactant may be used alone or in combination of two or more types. The surfactant content is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the cleaning agent for resin processing machines. When the surfactant content is within the aforementioned range, it is possible to improve the ease of substitution while maintaining cleaning performance.

[0047] (Antioxidants) Examples of antioxidants include phosphorus-based antioxidants and phenol-based antioxidants, but are not particularly limited to these. Specific examples of phosphorus-based antioxidants include tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, and 2,2'-methylenebis(4,6-di-t-butyl-1-phenyloxy)(2-ethylhexyloxy) phosphite. Specific examples of phenol-based antioxidants include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and 4,4'-butylidenebis(6-t-butyl-m-cresol). The antioxidants may be used individually or in combination of two or more.

[0048] The content of the antioxidant is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and even more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the cleaning agent for resin processing machines of the present embodiment. When the content of the antioxidant is within the above range, deterioration of the resin can be suppressed, and since the decomposition products of the antioxidant itself hardly have an inhibitory effect on other additives (such as lubricants), it is preferable.

[0049] (Inorganic foaming agent) In the present embodiment, the inorganic foaming agent refers to an inorganic compound that decomposes by heating to generate foam, that is, generate gas. Specific examples of the inorganic foaming agent include inorganic physical foaming agents such as water, hydrogen carbonate salts such as sodium hydrogen carbonate and ammonium hydrogen carbonate, carbonate salts such as sodium carbonate and ammonium carbonate, nitrite salts such as ammonium nitrite, hydrides such as sodium borohydride, azide compounds such as calcium azide, light metals such as magnesium and aluminum, combinations of sodium hydrogen carbonate and acids, combinations of hydrogen peroxide and yeast, combinations of aluminum powder and acids, and other known inorganic chemical foaming agents.

[0050] (Ultra-high molecular weight resin) In the present embodiment, the ultra-high molecular weight resin is a polymer having a viscosity average molecular weight of 1,000,000 or more. Examples include ethylene-based ultra-high molecular weight polymers, styrene-acrylonitrile-based ultra-high molecular weight polymers, methyl methacrylate-based ultra-high molecular weight polymers, and the like. Among these, it is preferable to use an ethylene-based ultra-high molecular weight polymer as the ultra-high molecular weight resin. The upper limit of the viscosity average molecular weight is not particularly limited, but generally it is preferably 10,000,000 or less for practical use.

[0051] Further, the ultra-high molecular weight resin may be a homopolymer or a copolymer. In the case of a copolymer, the content of the main component (for example, ethylene, styrene-acrylonitrile copolymer, methyl methacrylate, etc.) needs to be 50% by mass or more.

[0052] Furthermore, from the viewpoint of cleaning power and ease of substitution, the content of the ultra-high molecular weight resin is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.2 parts by mass or more and 7 parts by mass or less, and even more preferably 0.3 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the cleaning agent for resin processing machines according to this embodiment.

[0053] In this embodiment, the cleaning agent for resin processing machines is preferably composed of additives having a scrubbing effect, such as inorganic foaming agents and ultra-high molecular weight resins, in a quantity of 10 parts by mass or less, more preferably 7 parts by mass, and even more preferably 5 parts by mass, due to its easy substitution properties. Although the effect of additives having a scrubbing effect on substitution properties is not entirely clear, additives having a scrubbing effect, such as inorganic fillers, inorganic foaming agents, and ultra-high molecular weight resins, improve cleaning power, but tend to accumulate in the molding machine when the flow paths inside molds and dies are complex, such as in extrusion molding and injection molding, making discharge difficult and thus hindering substitution properties.

[0054] The content of the aforementioned other components is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the cleaning agent for resin processing machines.

[0055] In this embodiment, the cleaning agent for resin processing machines preferably contains water, for example, by adsorbing water onto the resin constituting the cleaning agent, or by making the resin constituting the cleaning agent porous to seal in water, thereby preventing water from escaping to the outside when the cleaning agent is introduced. Here, the amount of water to be contained is preferably 0.1% by mass or more in the cleaning agent for resin processing machines from the viewpoint of having a sufficient effect in peeling off residues, and preferably 10% by mass or less from the viewpoint of preventing water from escaping from the cleaning agent and remaining in the molding machine.

[0056] [Method for Manufacturing a Cleaning Agent for Resin Processing Machines] The method for manufacturing the cleaning agent for resin processing machines according to this embodiment is not particularly limited as long as it includes a melt-kneading step of melt-kneading (A) the thermoplastic resin, (B) the first filler, and (C) the second filler, and is capable of producing the cleaning agent for resin processing machines according to this embodiment as described above.

[0057] For example, a known compounding extruder can be used to obtain a cleaning agent composition, and a single-screw extruder, a multi-screw extruder including a twin-screw extruder, a heat-melt compounding machine using rolls, a kneader, a Brabender plastograph, a Banbury mixer, etc., can be used. Among these compounding extruders, a melt-melt compounding method using a twin-screw extruder is preferred. Specifically, the ZSK series from Coperion, Inc., the TEM series from Shibaura Machinery Co., Ltd., the TEX series from Japan Steel Works, Ltd., etc., can be used. For example, the L / D ratio (effective barrel length (L) / barrel inner diameter (D)) of the extruder is usually preferably 20 to 75, and more preferably 30 to 60.

[0058] The extruder described above preferably has a first raw material supply port upstream of the raw material flow direction, a second raw material supply port downstream of the first, and a vacuum vent further downstream. The total number of raw material supply ports of the extruder and their arrangement can be appropriately set considering the number of types of materials for the resin processing machine cleaning agent. Here, the method of supplying raw materials to the second raw material supply port is not particularly limited, but the method of supplying raw materials using a forced side feeder from the side opening of the extruder is more stable and therefore preferred over simply supplying raw materials from the open port of the second raw material supply port of the extruder.

[0059] Furthermore, while the temperature and screw rotation speed during melting and kneading are not particularly limited, it is preferable, for example, that the melting and kneading temperature is 180 to 300°C and the screw rotation speed is 100 to 1000 rpm.

[0060] Furthermore, in order to more reliably control the weight-average fiber length of the (B) glass fibers in the resin processing machine cleaning agent of this embodiment, it is preferable to manufacture the resin processing machine cleaning agent by carrying out the melt-kneading step included in (Manufacturing Method 1) or (Manufacturing Method 2) below.

[0061] (Manufacturing method 1) The melt-kneading step includes: Step (1-1): a step of melt-kneading the entire amount of component (A) and a portion of component (C); and Step (1-2): a step of adding the remainder of component (C) and the entire amount of component (B) to the melt-kneaded product obtained in Step (1-1), and melt-kneading.

[0062] In step (1-1), the entire amount of component (A) is kneaded, and in the subsequent step (1-2), components (C) and (B) are melt-kneaded. This allows for more reliable adjustment of the size (weight-average fiber length, number-average fiber length, average fiber diameter), shape, and content of components (B) and (C), resulting in the acquisition of a desired cleaning agent for resin processing machines.

[0063] (Manufacturing method 2) The melt-kneading step includes: step (1-1'): a step of melt-kneading the entire amount of component (A); and step (1-2'): a step of adding the entire amount of component (B) and the entire amount of component (C) to the melt-kneaded product obtained in step (1-1') and melt-kneading.

[0064] In step (1-1'), the entire amount of component (A) is kneaded, and in the subsequent step (1-2'), components (C) and (B) are melt-kneaded. This allows for more reliable adjustment of the size (weight-average fiber length, number-average fiber length, average fiber diameter), shape, and content of components (B) and (C), resulting in the acquisition of a desired cleaning agent for resin processing machines.

[0065] [Use of cleaning agent for resin processing machines] The cleaning agent for resin processing machines of this embodiment can be used for any resin molding machine without any particular limitations. Here, specific examples of resin processing machines include injection molding machines, extrusion molding machines, blow molding machines, hollow molding machines, inflation molding machines, and the like.

[0066] [Method for cleaning resin processing machinery] The method for cleaning resin processing machinery according to this embodiment is a method using the resin processing machine cleaning agent of this embodiment described above. The method for cleaning resin processing machinery according to this embodiment may include a step of allowing the resin processing machine cleaning agent described above to remain inside the resin processing machinery.

[0067] Specific examples of resin processing machines include those mentioned above. The resin processing machine cleaning agent of this embodiment is put into a molding machine and operates the molding machine almost normally to achieve a cleaning effect. It is particularly effective for injection molding machines and extrusion molding machines, but can be broadly applied to any device having a cylinder section that heats, melts, and kneads resin in a similar manner. When using the resin processing machine cleaning agent of this embodiment in a molding machine with a vent, it is preferable to add a portion of the cleaning agent through the vent opening. When using the resin processing machine cleaning agent of this embodiment, it is preferable to set the operating conditions of the molding machine to conditions that increase the internal pressure of the cylinder, as this makes the effect more pronounced. That is, it is preferable to perform operations such as lowering the cylinder temperature within the range where discharge is possible, applying back pressure, and injecting at high speed.

[0068] This embodiment will be described in detail below with reference to examples and comparative examples, but this embodiment is not limited to the examples and comparative examples described later, unless it exceeds the gist of the embodiment. Various measurement methods for the resin processing machine cleaning agent in the examples and comparative examples, and the raw material components of the resin processing machine cleaning agent used in the examples and comparative examples are shown below.

[0069] The melt mass flow rate (MFR) of the obtained thermoplastic resin was measured under conditions of 220°C and a load of 10 kg.

[0070] (Raw materials) (A) Thermoplastic resin (A-1) Styrene-acrylonitrile resin (AS) MFR: 9g / 10min (A-2) Block polypropylene resin (PP) MFR: 7g / 10min

[0071] (B) First filler (B-1) ECS03T-351 (manufactured by Nippon Electric Glass Co., Ltd., average fiber diameter 13 μm, chop length 3 mm)

[0072] (C) Second filler (C-1) Calcium carbonate, average particle size 6 μm (D) Ultra-high molecular weight polyethylene (D-1) Ultra-high molecular weight polyethylene polymer, UH950, manufactured by Asahi Kasei Corporation

[0073] (Manufacturing of cleaning agent for resin processing machines) In this embodiment, a sample of cleaning agent for resin processing machines was manufactured using a twin-screw extruder (TEM26SX manufactured by Shibaura Machinery Co., Ltd., 12 barrels). The twin-screw extruder used had a first raw material supply port upstream of the raw material flow direction, a second raw material supply port downstream of the first, and a vacuum vent downstream of the second raw material supply port. The raw material was supplied to the second raw material supply port using a forced side feeder from the side opening of the extruder. The mixing conditions were a barrel temperature of 250 to 280°C, a discharge rate of 15 kg / hour, and a screw rotation speed of 150 rpm. The extruder screw had one mixing block between the first and second raw material supply ports, and two mixing blocks downstream of the second raw material supply port. Of the two kneading blocks installed downstream of the second raw material supply port, the first kneading block was located in the seventh barrel of the extruder and consisted of two R-KD (feed type: R-type kneading discs), one N-KD (non-conveying type: N-type kneading disc), and one R-KD from upstream. The second kneading block was located in the ninth barrel of the extruder and consisted of two R-KD, one N-KD, and one L-KD (reverse feed: L-type kneading disc) from upstream. The molten kneaded material obtained in this way was extruded into a strand, water-cooled, and then cut with a strand cutter to prepare a sample of pellet-shaped cleaning agent for resin processing machines.

[0074] [Examples 1-2, Examples 5-8, Comparative Examples 1-5] Each component was blended in the proportions shown in Table 1, and melt-kneaded according to the manufacturing method described above.

[0075] [Example 3] The same procedure as in Example 1 was followed, except that the first kneading block (located in the seventh barrel) of the twin-screw extruder installed downstream of the second raw material supply port was replaced with a conveying block. A conveying block refers to a block that consists only of feed-type screw elements and does not have a kneading block.

[0076] [Example 4] The procedure was carried out in the same manner as in Example 1, except that the screw rotation speed of the twin-screw extruder was changed to 230 rpm. [Comparative Example 6] The procedure was carried out in the same manner as in Example 1, except that the screw from Example 3 was used and the screw rotation speed of the twin-screw extruder was changed to 100 rpm.

[0077] (Evaluation) Samples of cleaning agents for resin processing machines obtained in each example and comparative example were evaluated using the following method. The measurement and evaluation results are shown in Table 1.

[0078] (1) Glass fiber length The pellets of the resin processing machine cleaning agent obtained in the examples and comparative examples were heated in an electric furnace at 600°C for 1 hour and incinerated. From the residue, 200 glass fibers were arbitrarily selected, and their fiber lengths were measured using a stereomicroscope (Nikon SMZ1270). The weight-average fiber length, number-average fiber length, and the percentage of fibers with a length of 900 μm or more were calculated.

[0079] (2) Evaluation of cleaning power and replaceability One kilogram of black-colored ABS resin molding material was placed in an injection molding machine (EC100S manufactured by Shibaura Machine Co., Ltd.) with the cylinder and nozzle temperature raised to 200-240°C. After filling, the material was discharged by injection to empty the molding machine. Next, one kilogram of the resin processing machine cleaning agent shown in Table 1 was placed in the injection molding machine and an injection operation (cleaning injection operation) was performed. The amount of purged waste of the resin processing machine cleaning agent required until the influence of the black-colored ABS product was eliminated was measured. Finally, in order to replace the resin processing machine cleaning agent, three to four kilograms of GPPS transparent molding material were placed in the injection molding machine and an injection operation (replacement injection operation) was performed. The amount of purged waste of GPPS transparent molding material used was measured until it was confirmed that there was no influence of residual substances (foreign substances that impair transparency, coloring, etc.).

[0080] The amount of purged waste was evaluated according to the following criteria, and the results are shown in Table 1. Note that the less purged waste the resin processing machine cleaner is from the ABS black colored product, the better the cleaning power. (2-1) Cleaning power evaluation criteria ***: Purge waste amount is 0.3 kg or less, and cleaning performance is particularly good **: Purge waste amount is greater than 0.3 kg and 0.4 kg or less, and cleaning performance is even better *: Purge waste amount is greater than 0.4 kg and 0.5 kg or less, and cleaning performance is good In addition, the less purged waste the GPPS transparent molding material is from the resin processing machine cleaner, the better the substitution performance, and this was evaluated according to the following evaluation criteria.

[0081] (2-2) Criteria for evaluating replaceability ***: Purge waste volume is greater than 1.5 kg and 2.0 kg or less, indicating better replaceability **: Purge waste volume is greater than 2.0 kg and 2.5 kg or less, indicating good replaceability *: Purge waste volume is greater than 2.5 kg, making replacement from resin processing machine cleaning agent difficult

[0082] (3) Burn Removal Performance 150g of polyamide resin was placed in a small extruder (Plasticorder, manufactured by Brabender) heated to 320°C, and the screw was rotated to discharge the resin from the nozzle, allowing it to adhere to the inside of the small extruder. The extruder was then left at the same temperature for 90 minutes to create burn marks on the polyamide resin that remained attached to the inside of the extruder. Subsequently, 200g of the resin processing machine cleaning agent shown in Table 1 was added to the extruder to clean the inside. After that, the screw was removed, and the amount of remaining burn marks attached to the screw surface was measured, and the cleaning performance (burn removal performance) was evaluated according to the following evaluation criteria. (Evaluation Criteria) **: Remaining burn area is less than 30% of the total surface area of ​​the screw *: Remaining burn area is 30% or more of the total surface area of ​​the screw

[0083] (4) Pellet Inclusion Properties The pellets of the resin processing machine cleaning agent obtained in the examples and comparative examples were used in an injection molding machine (EC100S manufactured by Shibaura Machine Co., Ltd.) with the cylinder and nozzle temperature raised to 200-240°C. 1.5 kg of the resin processing machine cleaning agent shown in Table 1 was put into the injection molding machine, and weighing and purging operations (weighing injection operations) were performed under the conditions of a weighing stroke of 25 mm and a back pressure of 5 MPa. This operation was repeated 10 times, and the average time required for weighing one shot was determined. A shorter weighing time indicates better pellet inclusion properties.

[0084] (5) Area ratio of component (C) The pellets of the resin processing machine cleaning agent obtained in the examples and comparative examples were embedded and observed using SEM. A region corresponding to 316 × 237 μm was selected from the SEM observation image, and the image was binarized using image processing software (Adobe Photoshop Elements 2022) to remove (fill in) the (B) glass fiber phase, and the particle area and particle diameter of the extracted (C) component were measured in four images. From these images, the area was calculated from the particle diameter of each particle of the (C) component phase, and the ratio of the area of ​​component (C) with an average fiber diameter of component (B) or greater to the total area of ​​component (C) was calculated.

[0085]

[0086] Table 1 shows that the cleaning agents for resin processing machines in each example performed well in terms of evaluation results compared to the cleaning agents for resin processing machines in the comparative examples.

[0087] The cleaning agent for resin processing machines of the present invention can efficiently clean and discharge additives that are contained in the resin itself or molding materials such as dyes and pigments and remain in the molding machine at the end of predetermined operations in extrusion molding machines and injection molding machines. Therefore, it can be suitably used as a cleaning agent for resin processing machines for cleaning the inside of thermoplastic resin molding machines.

Claims

1. A cleaning agent for resin processing machines, comprising at least (A) a thermoplastic resin, (B) a first filler which is glass fiber, and (C) a second filler, wherein the weight-average fiber length of the first filler (B) is 650 to 1600 μm.

2. The cleaning agent for resin processing machines according to claim 1, characterized in that it contains 25 to 140 parts by mass of the first filler (B) and 25 to 140 parts by mass of the second filler (C) per 100 parts by mass of the thermoplastic resin (A).

3. The cleaning agent for resin processing machines according to claim 1 or 2, characterized in that the total content of the first filler (B) and the second filler (C) is 50 to 200 parts by mass per 100 parts by mass of the thermoplastic resin (A).

4. The cleaning agent for resin processing machines according to claim 1 or 2, characterized in that the mass ratio of the first filler (B) to the second filler (C) is 90 / 10 to 10 / 90.

5. The cleaning agent for resin processing machines according to claim 1 or 2, characterized in that the second filler (C) is an inorganic filler other than glass fiber.

6. The cleaning agent for resin processing machines according to claim 5, characterized in that the second filler (C) is calcium carbonate and / or talc.

7. The cleaning agent for resin processing machines according to claim 1 or 2, characterized in that the (A) thermoplastic resin includes at least one selected from the group consisting of styrene resins, polyolefin resins, and methacrylic acid resins.

8. The cleaning agent for resin processing machines according to claim 7, characterized in that the thermoplastic resin (A) comprises at least a styrene-based resin.

9. The cleaning agent for resin processing machines according to claim 8, characterized in that the styrene-based resin is a styrene-acrylonitrile copolymer.

10. The cleaning agent for resin processing machines according to claim 7, characterized in that the thermoplastic resin (A) contains a styrene resin and a polyolefin resin, and the mass ratio of the styrene resin to the polyolefin resin is 99 / 1 to 85 / 15.

11. The cleaning agent for resin processing machines according to claim 1 or 2, characterized in that the content ratio of fillers with a fiber length of 900 μm or more among the first fillers of (B) is 10% by mass or more.

12. The cleaning agent for a resin processing machine according to claim 1 or 2, characterized in that, in an electron microscope image of the cleaning agent for the resin processing machine, the ratio of the area of ​​the second filler (C), which is equal to or greater than the average fiber diameter of the first filler (B), to the total area of ​​the second filler (C) observed is 5% or more.

13. The cleaning agent for resin processing machines according to claim 1 or 2, characterized in that the ratio of the weight-average fiber length (Lw) to the number-average fiber length (Ln) (Lw / Ln) of the first filler (B) is 1.16 to 1.

50.

14. The cleaning agent for resin processing machines according to claim 1 or 2, characterized in that the average fiber diameter of the first filler (B) is 9 to 15 μm.

15. A method for producing a cleaning agent for a resin processing machine according to claim 1 or 2, comprising a melt-kneading step of melt-kneading the (A) thermoplastic resin, the (B) first filler, and the (C) second filler, wherein the melt-kneading step comprises: step (1-1): melt-kneading the entire amount of the (A) thermoplastic resin and a portion of the (C) second filler; and step (1-2): adding the remainder of the (C) second filler and the entire amount of the (B) first filler to the melt-kneaded product obtained in step (1-1), and melt-kneading the mixture.

16. A method for producing a cleaning agent for a resin processing machine according to claim 1 or 2, comprising a melt-kneading step of melt-kneading the (A) thermoplastic resin, the (B) first filler, and the (C) second filler, wherein the melt-kneading step comprises: step (1-1'): melt-kneading the entire amount of the (A) thermoplastic resin, and step (1-2'): adding the entire amount of the (B) first filler and the entire amount of the (C) second filler to the melt-kneaded product obtained in step (1-1'), and melt-kneading the mixture.

17. A method for cleaning a resin processing machine using the resin processing machine cleaning agent described in claim 1.

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