JP2024022569A - Resin composition for cleaning agent for resin processing machinery - Google Patents

Abstract

To provide a resin composition for a cleaning agent for resin processing machines excellent in cleaning performance, easy replaceability by a molding material after cleaning and thermal stability.SOLUTION: There is provided a resin composition for a cleaning agent for resin processing machines which comprises at least (A) a polyethylene-based resin and (B) a crosslinked polyethylene-based resin, wherein the mass ratio of the polyethylene-based resin (A) is 90 to 10 pts.mass and the mass ratio of the crosslinked polyethylene-based resin (B) is 10 to 90 pts.mass, based on the total 100 pts.mass of the polyethylene-based resin (A) and the crosslinked polyethylene-based resin (B), and the resin composition satisfies the following (1) or (2). (1) The melt mass flow rate is 0.1 to 2.0 g/10 min. (2) the ratio of a polyethylene-based resin and a cross-linked polyethylene-based resin having a molecular weight of 3000000 or more as determined by gel permeation chromatography is 1.8% or more.SELECTED DRAWING: None

Description

The present invention relates to a resin composition for a cleaning agent for resin processing machines.

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, but in these types of processing machines, when the specified work is completed, the resin itself In addition to additives such as dyes and pigments contained in molding materials and molding materials, deterioration products generated from resins (e.g., thermal decomposition products, burnt products, carbides, etc.) may remain in resin processing machines. . If this residue is left unattended, it will be mixed into the molded product during the subsequent resin molding process, and may cause poor product appearance. In particular, when molding transparent resin, even minute carbides are easily visible, resulting in poor appearance of the molded product and increasing the incidence of molded product defects. Therefore, it is desired to completely remove the residue from inside the resin processing machine.

Conventionally, in order to remove the residue from inside the resin processing machine, there were two methods: (1) manually disassembling and cleaning the resin processing machine, and (2) using the molding material for the next molding without stopping the resin processing machine. Methods include filling a resin processing machine with the resin and gradually discharging the residue, and (3) using a cleaning agent.

The method (1) above is inefficient because it requires stopping the resin processing machine, and the resin processing machine is easily damaged because the removal work is physically performed manually. Method (2) above often requires a large amount of molding material to remove the residue, takes time to complete the work, and also has the problem of generating a large amount of waste. . Therefore, in recent years, the method (3) using a cleaning agent has been preferred because it has excellent cleaning power to remove residues from resin processing machines.

In order to increase the effectiveness of cleaning agents, various methods have been proposed for increasing the cleaning power of cleaning agents. For example, Patent Documents 1 and 2 describe a method of increasing detergency by blending a crosslinked olefin resin.

Japanese Patent Application Publication No. 2002-210748 Japanese Patent Application Publication No. 2007-262383

The cleaning agent is required to have high cleaning power for the molding material used in the previous molding and to be easily replaceable by the molding material used in the next molding.
The cleaning agent of Patent Document 1 describes the use of a polyethylene resin having a gel fraction of 5 to 25% alone or in combination with a surfactant, but there was a problem that the cleaning effect was insufficient.
The cleaning agent in Patent Document 2 describes a cleaning agent in which high-density polyethylene resin and crosslinked polyethylene are pulverized and mixed with an inorganic filler and extruded into pellets using a twin-screw extruder. There was a problem with insufficient substitutability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a resin composition for a cleaning agent for resin processing machines that is excellent in cleaning performance, easy replacement by a molding material after cleaning, and thermal stability.

As a result of intensive studies to solve the above problems, the present inventors have determined that the MFR or We have discovered that by controlling the total proportion of polyethylene resins with a molecular weight of 3 million or more and crosslinked polyethylene resins contained in the resin composition within a specific range, excellent cleaning performance, easy displacement, and thermal stability can be achieved. This led to the development of an invention.

That is, the present invention is as follows.
[1]
Containing at least (A) a polyethylene resin and (B) a crosslinked polyethylene resin,
The mass proportion of the (A) polyethylene resin is 90 to 10 parts by mass to the total of 100 parts by mass of the (A) polyethylene resin and the (B) crosslinked polyethylene resin, and the (B) crosslinked polyethylene resin A resin composition for a cleaning agent for resin processing machines, wherein the mass proportion of the resin is 10 to 90 parts by mass, and the following (1) or (2) is provided.
(1) Melt mass flow rate (MFR 220°C, load 10 kg) is 0.1 to 2.0 g/10 min. (2) Polyethylene resin and crosslinked polyethylene resin contained in the resin composition for cleaning agent for resin processing machines. The ratio of the total of polyethylene resins and crosslinked polyethylene resins with a molecular weight of 3,000,000 or more determined by gel permeation chromatography (GPC, mobile phase: o-dichlorobenzene, standard material: polystyrene) to the total is 1 .8% or more [2]
The resin composition for a cleaning agent for resin processing machines according to [1], which has a gel fraction (according to JIS K6796) of 0.3 to 4.5%.
[3]
The resin processing according to [1] or [2], wherein the polyethylene resin (A) is linear low-density polyethylene with an MFR (190° C., load 2.16 kg) of 0.1 to 1.5 g/10 minutes. Resin composition for machine cleaners.
[4]
The resin composition for a cleaning agent for resin processing machines according to any one of [1] to [3], wherein the crosslinked polyethylene resin (B) has a gel fraction (according to JIS K6796) of 10 to 45%.
[5]
The cleaning agent for resin processing machines according to any one of [1] to [4], wherein the crosslinked polyethylene resin (B) has an MFR (220° C., load 10 kg) of 0.01 to 0.50 g/10 minutes. Resin composition for use.
[6]
The resin composition for a cleaning agent for resin processing machines according to any one of [1] to [5], wherein the crosslinked polyethylene resin (B) is a crosslinked polyethylene resin crosslinked by peroxide or electron beam crosslinking. .
[7]
The resin composition for a cleaning agent for resin processing machines according to any one of [1] to [6], wherein the crosslinked polyethylene resin (B) is a crosslinked polyethylene resin obtained by a manufacturing method including recycling or volume reduction. thing.
[8]
A method for cleaning resin processing machines, comprising using the resin composition for cleaning agents for resin processing machines according to any one of [1] to [7].

According to the present invention, it is possible to provide a resin composition for a cleaning agent for resin processing machines that is excellent in cleaning performance, easy replacement by a molding material after cleaning, and thermal stability.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail. The present embodiment below is an illustration for explaining the present invention, and the present invention is not limited to the following content. The present invention can be implemented with various changes within the scope of its gist.

[Resin composition for cleaning agent]
The resin composition for a cleaning agent for resin processing machines of the present embodiment (hereinafter may simply be referred to as "resin composition for cleaning agent" or "cleaning agent") is a polyethylene resin (A) (hereinafter referred to as "resin composition for cleaning agent" or "cleaning agent"). ) and (B) a crosslinked polyethylene resin (sometimes referred to as "B component" in this specification), the (A) component and the (B) component. and the mass proportion of component (A) is 90 to 10 parts by mass, and the mass proportion of component (B) is 10 to 90 parts by mass, and the melt mass flow rate of the resin composition for cleaning agent is 100 parts by mass in total. (MFR 220°C, load 10 kg) is 0.1 to 2.0 g/10 minutes.
Further, another resin composition for a cleaning agent of this embodiment includes at least component (A) and component (B), and based on a total of 100 parts by mass of component (A) and component (B), The mass proportion of the component (A) is 90 to 10 parts by mass, the mass proportion of the component (B) is 10 to 90 parts by mass, and the polyethylene resin and crosslinked polyethylene resin contained in the resin composition for a cleaning agent for resin processing machinery The ratio of the total of polyethylene resin and crosslinked polyethylene resin with a molecular weight of 3,000,000 or more determined by gel permeation chromatography (GPC, mobile phase: o-dichlorobenzene, standard material: polystyrene) to the total resin , 1.8% or more.
The resin composition for a cleaning agent of the present embodiment may be a composition consisting only of (A) polyethylene resin and (B) crosslinked polyethylene resin, or may be a composition consisting only of (A) polyethylene resin and (B) ) It may be a composition containing a crosslinked polyethylene resin and other components.

Hereinafter, each component of the resin composition for detergent of this embodiment will be explained in detail.

<(A) Polyethylene resin>
Examples of the polyethylene resin include polyethylene, ethylene-α-olefin copolymer, etc. Specifically, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE) , linear very low density polyethylene (VLDPE, ULDPE), and the like. Among these, linear low-density polyethylene is more preferred from the viewpoint of cleaning performance.
(A) The polyethylene resin can be used alone or in a blend of two or more.

The polyethylene resin (A) used in this embodiment can be manufactured using a known manufacturing method, but generally includes a Ziegler type catalyst consisting of a transition metal compound such as titanium or zirconium, a magnesium compound, and an organoaluminum compound, or a chromium-based A Phillips-type catalyst mainly consisting of a metallocene-type catalyst containing at least one cyclopentadienyl group or substituted cyclopentadienyl group in a transition metal such as zirconium, hafnium, or titanium is used as a polymerization catalyst, and ethylene or ethylene and carbon are used as polymerization catalysts. It can be suitably produced by copolymerizing several 3 to 20 α-olefins in proportions that give the desired density.

Examples of the α-olefin used in copolymerization with ethylene include propylene, 1-butene, 4-methyl-1-pentene, 3-methyl-1-butene, 1-pentene, 1-hexene, and 1-heptene. , 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1 -eicosene, etc., and one or more types of α-olefins can be copolymerized.

(A) The MFR (190°C, load 2.16 kg) of the polyethylene resin is preferably 0.1 to 1.5 g/10 minutes, more preferably 0.2 to 1.0 g/10 minutes, and Preferably it is 0.5 to 0.9 g/10 minutes. If the MFR is less than 0.1 g/10 minutes, the load on resin processing machines such as a melt kneader will increase, and if it exceeds 1.5 g/10 minutes, the cleaning performance will decrease.

(A) The polyethylene resin may be a non-crosslinked polyethylene resin.

<(B) Crosslinked polyethylene resin>
The (B) crosslinked polyethylene resin used in this embodiment is high density polyethylene, linear low density polyethylene, branched low density polyethylene, ethylene/vinyl acetate copolymer (EVA), chlorinated polyethylene, ethylene/ethyl acrylate. Examples include crosslinked polyethylene resins such as copolymers, and one or more of these can be used in combination.
There are no particular restrictions on the crosslinking method, and electron beam crosslinking, peroxide crosslinking, and water crosslinking (also called silane crosslinking), in which a silane compound is grafted and then brought into contact with water, are used. From this point of view, electron beam crosslinking and peroxide crosslinking are more preferred.

(B) The gel fraction (according to JIS K6796) of the crosslinked polyethylene resin is preferably 10 to 45%, more preferably 25 to 35%. When using two or more types of (B) components, it is preferable that the gel fraction of all the crosslinked polyethylene resins is within the above range.

(B) The MFR (220° C., load 10 kg) of the crosslinked polyethylene resin is preferably 0.01 to 0.50 g/10 minutes, more preferably 0.03 to 0.40 g/10 minutes. By setting the content within the above range, a cleaning resin composition having excellent cleaning performance and easy replaceability can be obtained.

(B) Cross-linked polyethylene resin refers to cross-linked polyethylene resin molded products such as used electric wire covering materials, pipe materials for floor heating, films, various foams, reduced volume products, and cross-linked polyethylene resin products generated during the manufacturing stage of these products. It may be a pulverized product such as resin waste, and recycled products or volume-reduced products obtained by including a plasticization step using an extruder are more preferable. In this specification, recycled cross-linked polyethylene and volume-reduced products mean that the carbon-carbon bonds in the cross-linked portion of cross-linked polyethylene are severed to improve the fluidity of the resin, and the recycle and volume-reduced temperatures refer to the This refers to the temperature at which regeneration and volume reduction are possible. The regeneration and volume reduction temperature is preferably 120 to 400°C, more preferably 180 to 380°C, and even more preferably 250 to 350°C. When the regeneration and volume reduction temperature is less than 120° C., plasticization becomes difficult and the crosslinked polyethylene becomes difficult to be recycled and volume reduced. On the other hand, if the regeneration or volume reduction temperature exceeds 400° C., molecular cleavage of the crosslinked polyethylene resin proceeds excessively, and the properties of the resulting crosslinked polyethylene resin deteriorate. Normally, cross-linked polyethylene resin has a three-dimensional network structure, so it does not melt even at temperatures above its melting point. It is presumed that the compatibility with the components and/or the ease of substitution are improved (however, the effects of this embodiment are not limited to this).

The resin composition for a detergent of this embodiment is comprised of the above-described components (A) and (B) as basic components.
The mass ratio of (A) polyethylene resin and (B) crosslinked polyethylene resin (mass of (A) component/mass of (B) component) in the resin composition for cleaning agent of this embodiment is determined by the detergency, From the viewpoint of manufacturing stability, it is 90/10 to 10/90, preferably 80/20 to 20/80, more preferably 70/30 to 20/80, most preferably 70/30 to 30/70. selected from the range of

The ratio of the total mass of components (A) and (B) to 100 parts by mass of the resin composition for detergents of the present embodiment is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and It is preferably 95 parts by mass or more, preferably 100 parts by mass or less, and may be less than 100 parts by mass.

The resin composition for cleaning agent of the present embodiment contains component (A) and component (B) in a specific mass ratio, and the MFR in the resin composition for cleaning agent or the polyethylene-based resin composition contained in the resin composition for cleaning agent is By setting the ratio of the total of the polyethylene resin with a molecular weight of 3 million or more and the crosslinked polyethylene resin to the total of the resin and the crosslinked polyethylene resin within a specific range, cleaning performance, easy replacement property, and thermal stability are achieved.
The MFR (220° C., load 10 kg) of the detergent resin composition of this embodiment is preferably 0.1 to 2.0 g/10 minutes, more preferably 0.3 to 1.8 g/10 minutes. As a method for adjusting the MFR to the above range, for example, using linear low density polyethylene as the component (A) (for example, using linear low density polyethylene having an MFR within the above range as the component (A)) ), adjusting the mass ratio of component (A) and component (B) to the above range, etc., and it is preferable to use linear low density polyethylene as component (A).
The specific range is the ratio of the total of polyethylene resin and crosslinked polyethylene resin with a molecular weight of 3,000,000 or more to the total of polyethylene resin and crosslinked polyethylene resin contained in the resin composition for cleaning agent of this embodiment. By doing so, a resin composition having excellent cleaning performance and thermal stability can be obtained. Specifically, the above-mentioned ratio of the total of the polyethylene resin having a molecular weight of 3,000,000 or more and the crosslinked polyethylene resin is preferably 1.8% or more, and more preferably 1.9% or more. The upper limit of the total ratio of the polyethylene resin having a molecular weight of 3,000,000 or more and the crosslinked polyethylene resin is not particularly limited, but is preferably 3.5% or less.
In order to keep the above ratio of polyethylene resin with a molecular weight of 3,000,000 or more and crosslinked polyethylene resin in the detergent resin composition within a specific range, for example, the temperature and screw rotation speed during melt-kneading of the extruder must be adjusted. , preferably controlled by a screw configuration.
In addition, the ratio of the total of polyethylene resins and crosslinked polyethylene resins with a molecular weight of 3,000,000 or more to the total of polyethylene resins and crosslinked polyethylene resins contained in the resin composition for cleaning agents is determined by gel permeation chromatography. (GPC). The device was "HLC-8321GPC/HT type" manufactured by Tosoh Corporation, the detector was a differential refractometer (RI), the solvent was o-dichlorobenzene, and the column was "TSKgel-GMH6-" manufactured by Tosoh Corporation. Two bottles of ``HT'' and two bottles of ``TSKgel-GMH6-HTL'' were used. Pretreatment for GPC measurement involves adding 20 ml of mobile phase for GPC measurement to 20 mg of sample, shaking and dissolving at 145°C, heat-filtering the solution through a sintered filter with a pore size of 1.0 μm, and using the filtrate for GPC measurement. It was used for. Based on the obtained elution curve, the molecular weight was calculated in terms of polystyrene. Further, the above ratio was calculated using an integral molecular weight distribution curve. The presence of polyethylene resins and crosslinked polyethylene resins having a molecular weight of 3,000,000 or more can be confirmed by the difference in the refractive index of RI.

The gel fraction (according to JIS K6796) of the detergent resin composition of this embodiment is preferably 0.3 to 4.5%, more preferably 0.4 to 2.0%. It is presumed that the gel fraction is controlled by adjusting the MFR of the resin composition within the above-mentioned range (however, the effects of this embodiment are not limited thereto).
In addition, as another method for adjusting the gel fraction of the detergent resin composition of the present embodiment within the above range, for example, the mass ratio of the (A) component and the (B) component is adjusted (for example, as described above). (adjusting the MFR to a preferable range), and using linear low-density polyethylene having an MFR within the above-mentioned range as component (A).

<Other ingredients>
The detergent resin composition of the present embodiment may contain other components than the above component (A) and the above component (B), as long as the effects of the present invention are not adversely affected.
Other components mentioned above include thermoplastic resins other than component (A) and component (B), stabilizers such as antioxidants, light stabilizers, and ultraviolet absorbers, and lubricants in order to provide their respective effective effects. , surfactants, antiblocking agents, antistatic agents, antifogging agents, nucleating agents, crosslinking promoters, crosslinking inhibitors, inorganic fillers such as talc, calcium carbonate, mica, titanium oxide, colorants, aliphatic hydrocarbon compounds , an inorganic foaming agent, etc. can be used as appropriate.

(Aliphatic hydrocarbon compound)
The cleaning agent resin composition of this embodiment may contain an aliphatic hydrocarbon compound. The aliphatic hydrocarbon compound is not particularly limited as long as it has a weight average molecular weight of 200 to 20,000, and includes mineral oil, paraffin wax, olefin wax, and the like.
The above-mentioned mineral oil is an oil obtained by refining petroleum, and is a saturated hydrocarbon oil containing naphthenes, isoparaffins, etc., also called mineral oil, lubricating oil, liquid paraffin, etc. Mineral oils with a wide viscosity range can be used. For example, in the case of liquid paraffin, those with a kinematic viscosity of 50 to 500 mm ² /s measured according to JIS K2283, the Redwood method (Japan Oil Chemists Association standard oil and fat analysis test method) 2.2.10.4-1996) with a viscosity in the range of 30 to 2000 (seconds) may be used. The above-mentioned paraffin wax is a paraffin compound obtained by refining petroleum and is solid at room temperature, and those having a melting point of 40 to 80°C are often used.

The olefin waxes include low-molecular polyolefins, and are not particularly limited, but general low-density or high-density polyethylene, polypropylene, etc. are used. Those with a weight average molecular weight of about 800 to 20,000 and a dropping point of 80 to 180°C are most effective.

The content of the aliphatic hydrocarbon compound is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 0.05 to 15 parts by mass, based on 100 parts by mass of the resin composition for cleaning agent. More preferably, it is 0.1 to 10 parts by mass. When the content of the aliphatic hydrocarbon compound is within the above range, the ease of substitution can be improved while maintaining the washability. In addition, by adding an aliphatic hydrocarbon compound, the motor load (torque) of a kneader such as a twin-screw extruder is reduced during kneading of the resin composition for cleaning agents, making it easier to manufacture the resin composition for cleaning agents. become.

(Lubricant)
Examples of the lubricant include organic acids, organic acid metal salts, organic acid amides, organic acid derivatives such as organic acid esters, various ester waxes, fluorine resins, etc., but are not particularly limited thereto. Note that the above-mentioned lubricant does not contain the above-mentioned aliphatic hydrocarbon compound. The lubricants may be used alone or in combination of two or more.

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. A portion of the chain may have a hydroxyl group. In particular, from the viewpoint of availability and heat resistance, stearic acid, 12-hydroxystearic acid, palmitic acid, myristic acid, and lauric acid are more preferred. Further, mixed fatty acids having different alkyl chains may be used. When the number of carbon atoms is within the above range, it is preferable because there is no problem of gas generation or odor, it is easily available, and its properties as a lubricant at the interface function well.

The metal in the organic acid metal salt is not particularly limited, but includes sodium, potassium, lithium, cesium, magnesium, calcium, aluminum, zinc, iron, cobalt, barium, and the like. Among these, lithium, calcium, barium, zinc, and aluminum are preferred because they are most effective as lubricants. Among these, aluminum and zinc are more preferable because they have low polarity and tend to exhibit external slipperiness due to bleed-out from the thermoplastic resin. Particularly preferred is zinc.

The hydrocarbon moiety in the above-mentioned organic acid metal salt 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, as is the case with the above-mentioned organic acids, and these are easy to obtain and have good heat resistance. From this viewpoint, stearic acid, 12-hydroxystearic acid, palmitic acid, myristic acid, and lauric acid are more preferred.

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

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

Examples of the fluororesin include PTFE, PFA, PVDF, PVDF copolymer, ETFE, PFE, etc., and can be expected to have the effect of suppressing resin adhesion to metal surfaces. Various shapes can be used, such as pellets and powders, but powders are particularly preferred in order to ensure 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, and the surface tension of aluminum stearate is 25 mN/m. Further, the melting point or softening point of the lubricant is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher.

The content of the lubricant is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight based on 100 parts by weight of the resin composition for detergent. Part by mass. When the content of the lubricant is within the above range, easy replacement can be improved while maintaining cleanability.

(surfactant)
Examples of the surfactant include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and the like. Examples of the anionic activator include higher fatty acid alkali salts (alpha sulfo fatty acid methyl ester sodium, etc.), alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, sulfosuccinate ester salts, and the like. Examples of the cationic activator include higher amine halide salts, alkylpyridinium halides, and quaternary ammonium salts. Examples of the nonionic activator include polyethylene glycol alkyl ether, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, pentaerythritol fatty acid ester (pentaerythritol tetrastearate, etc.), fatty acid monoglyceride, and the like. Examples of amphoteric surfactants include amino acids. The surfactants may be used alone or in combination of two or more.

The content of the surfactant is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 10 parts by weight, and even more preferably 0.5 parts by weight based on 100 parts by weight of the resin composition for detergent. ~8 parts by mass. When the content of the surfactant is within the above range, easy replacement can be improved while maintaining cleanability.

(Antioxidant)
Examples of the antioxidant include phosphorus antioxidants, phenolic antioxidants, etc., but are not particularly limited to these. Specific examples of phosphorous 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 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. The antioxidants may be used alone or in combination of two or more.

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 parts by mass based on 100 parts by mass of the resin composition for cleaning agent. ~2 parts by mass. When the content of the antioxidant is within the above range, deterioration of the resin can be suppressed, and the decomposition products of the antioxidant themselves do not have an inhibitory effect on other additives (such as lubricants). It is preferable because it is less.

(Inorganic filler)
In the present embodiment, the inorganic filler refers to an inorganic compound other than the inorganic blowing agent described below, and includes both natural products and artificial compounds. Specific examples of inorganic compounds include talc, mica, wollastonite, xonotlite, kaolin clay, montmorillonite, bentonite, sepiolite, imogolite, sericite, lawsonite, smectite, calcium sulfate fiber, calcium carbonate, magnesium carbonate, titanium oxide, and water. Examples include aluminum oxide, magnesium hydroxide, zeolite, diatomaceous earth, glass powder, glass bulbs, glass fibers, and shirasu balloons.

(Inorganic foaming agent)
In this embodiment, the inorganic foaming agent refers to an inorganic compound that decomposes upon heating and foams, that is, generates gas. Specific examples of inorganic blowing agents include inorganic physical blowing 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. Known compounds such as 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, and combinations of aluminum powder and acids, etc. Inorganic chemical blowing agents may be mentioned.

(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 million or more, such as an ethylene-based ultra-polymer, a styrene-acrylonitrile-based ultra-polymer, a methyl methacrylate-based ultra-polymer, etc. It will be done. Among these, ethylene-based superpolymers are preferred. The upper limit of the viscosity average molecular weight is not particularly limited, but is generally preferably 10 million or less for practical purposes.

Further, the ultra-high molecular weight resin may be a homopolymer or a copolymer, and in the case of a copolymer, the content of the main component (for example, 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 ultra-high molecular weight resin is preferably 0.1 parts by mass or more and 10 parts by mass or less, and 0.1 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the resin composition for detergent. It is more preferably 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.

In order to easily replace the resin composition for a cleaning agent of the present embodiment, the content of the above-mentioned inorganic filler, inorganic foaming agent, ultra-high molecular weight resin, and other additives having a scrubbing effect is 10 parts by mass or less. It is preferably 7 parts by mass, more preferably 5 parts by mass.

Although the effect of additives with a scrubbing effect on substitutability is not necessarily clear, additives with a scrubbing effect such as inorganic fillers, inorganic blowing agents, and ultra-high molecular weight resins improve detergency while extrusion molding and If the flow path inside a mold or die for injection molding is complicated, it is likely to accumulate in the molding machine, making it difficult to discharge and impeding replacement performance (however, the effect is not limited to this).

The content of 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, based on 100 parts by mass of the resin composition for detergent.

[Method for producing resin composition for cleaning agent]
The method for producing the resin composition for detergents of this embodiment is not particularly limited as long as it is a method that can produce the resin composition for detergents of this embodiment described above.

The method for producing the cleaning resin composition of this embodiment is not particularly limited, and any known kneader can be used, such as a single-screw extruder, a multi-screw extruder including a twin-screw extruder, a roll, Examples include heating melt kneading machines such as a kneader, Brabender Plastograph, and Banbury mixer. Among the above, a melt-kneading method using a twin-screw extruder is preferred. Specifically, the ZSK series manufactured by Coperion, the TEM series manufactured by Shibaura Machinery Co., Ltd., the TEX series manufactured by Japan Steel Works, Ltd., etc. can be used. For example, the L/D ratio (barrel effective length (L)/barrel inner diameter (D)) of the extruder is usually preferably 20 to 75, more preferably 30 to 60.

The melt-kneading temperature and screw rotation speed are not particularly limited, but it is usually preferable that the melt-kneading temperature is 180 to 300° C. and the screw rotation speed is 100 to 1000 rpm.

[Use of resin composition for cleaning agent]
The resin composition for cleaning agent of this embodiment can be used for any resin molding processing machine without any particular restrictions.
Specific examples of resin processing machines include injection molding machines, extrusion molding machines, and the like.

[How to clean resin processing machines]
The method for cleaning a resin processing machine according to the present embodiment is a method using the above-described resin composition for cleaning agent according to the present embodiment. The method for cleaning a resin processing machine according to the present embodiment may include a step of retaining the above-described resin composition for a cleaning agent in the resin processing machine.
Specific examples of resin processing machines include those mentioned above.
The cleaning method for a resin processing machine according to the present embodiment not only allows the molded material to be efficiently discharged before cleaning, but also allows the cleaning agent resin composition to be removed from the resin when the resin processing machine is stopped after cleaning. By allowing the resin to remain in the resin processing machine in a full state, even if the material that was molded before cleaning remains in the resin processing machine due to insufficient cleaning, there is the advantage that thermal deterioration of the remaining material can be prevented.

Hereinafter, the present embodiment will be specifically described with reference to Examples and Comparative Examples, but the present embodiment is not limited to the Examples and Comparative Examples described below unless the gist thereof is exceeded. Various measuring methods for the resin compositions for detergents of Examples and Comparative Examples and the raw material components of the resin compositions for detergents used in Examples and Comparative Examples are shown below.

Measurements of each material were performed as follows.

[Melt mass flow rate (MFR)]
The MFR of the polyethylene resin was measured at 190° C. and a load of 2.16 kg. The MFR of the crosslinked polyethylene resin was measured at 220° C. and a load of 10 kg.

[Gel fraction]
The gel fraction of crosslinked polyethylene was measured according to JIS K6796.

[raw materials]
(A) Polyethylene resin (A-1) Linear low density polyethylene resin MFR: 0.8 g/10 minutes (A-2) High density polyethylene resin MFR: 0.3 g/10 minutes (A-3) Linear chain Low density polyethylene resin MFR: 3.0 g/10 minutes (B) Crosslinked polyethylene resin (B-1) Obtained by adding peroxide dicumyl peroxide to low density polyethylene (MFR: 2.3 g/10 minutes) A cross-linked polyethylene resin made by reducing the volume of foamed cross-linked polyethylene using a 95 mmφ single-screw extruder at a barrel temperature of 300°C. Gel fraction: 34%, MFR: 0.19 g/10 min.

[Manufacture of resin composition for cleaning agent]
In this example, a cleaning resin composition was produced using a twin-screw extruder (manufactured by Shibaura Kikai Co., Ltd.) TEM-26SX extruder. The kneading conditions were a cylinder temperature of 210 to 240°C, a discharge rate of 15 kg/hour, and a screw rotation speed of 150 rpm. The melt-kneaded product thus obtained was extruded into a strand shape, cooled with water, and then cut with a strand cutter to obtain a pellet-shaped resin composition for a detergent.

[Examples 1-3, Comparative Examples 1-2]
Each component was blended in the proportions shown in Table 1, and melt-kneaded by the above-mentioned manufacturing method. Using the obtained pellets, evaluation was performed by the following method. The measurement and evaluation results are shown in Table 1.

(1) MFR
The MFR of the resin composition was measured at 190°C and a load of 2.16kg and at 220°C and a load of 10kg.

(2) Molecular weight The ratio of the total of polyethylene resin and crosslinked polyethylene resin with a molecular weight of 3,000,000 or more to the total of polyethylene resin and crosslinked polyethylene resin contained in the resin composition is determined using an integral molecular weight distribution curve. It was measured by the following GPC.
Equipment: Manufactured by Tosoh Corporation, “HLC-8321GPC/HT type”
Detector: Differential refractometer (RI)
Solvent: o-dichlorobenzene (contains 0.025% by mass BHT)
Flow rate: 1.0ml/min
Sample concentration: 1mg/1ml
Column temperature: 140℃
Columns: Two columns of "TSKgel-GMH6-HT" and two columns of "TSKgel-GMH6-HTL" manufactured by Tosoh Corporation were used. Based on the elution curves obtained, calculations were made in terms of polystyrene.

(3) Gel fraction The gel fraction of the resin composition was measured in accordance with JIS K6796. Specifically, 0.5 g of the sample was placed in a folded bag made of 130 mesh stainless steel wire mesh, extracted for 8 hours in a good solvent for the sample, and the weight of the sample after extraction was weighed after drying with hot air at 140°C for 3 hours. did. The proportion of insoluble matter was determined using the following formula. In Examples and Comparative Examples, xylene was used as a good solvent.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) x 100

(4) Cleanability evaluation (color change performance)
A blue-colored low-density polyethylene (Suntec M1920 manufactured by Asahi Kasei Corporation) was used as a colored masterbatch, and 10% by mass of the colored masterbatch and 90% by mass of linear low-density polyethylene were mixed. 0.5 kg of the resin mixture was put into a molding machine (Plasticorder), and the screw was rotated to discharge the resin mixture from the die, thereby causing pseudo dirt to adhere to the inside of the molding machine.
Thereafter, 1 kg of the detergent resin compositions obtained in the 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 waste discharged from the die, the purge waste was discharged until cleaning was completed. The amount (g) of discharged purge waste was measured using a balance, and the cleaning performance (color change performance) was evaluated using the following evaluation criteria.
Note that cleaning was completed when the color tone of the purge waste discharged from the die during cleaning was cooled to room temperature and solidified, changing from blue to the color of the cleaning resin composition.
+++: The amount of purge waste discharged is less than 200g++: The amount of purge waste discharged is 200g or more and less than 250g.+: The amount of purge waste discharged is 250g or more.

(5) Replaceability evaluation After the above (cleanability evaluation), 1 kg of linear low-density polyethylene was put into a small extruder (Plasticorder manufactured by Brabender) under the conditions of a cylinder temperature of 200°C and a die temperature of 200°C. The purge waste was discharged by rotating the screw, and while visually observing the color tone of the appearance of the molten resin discharged from the die, the purge waste was discharged until the displacement was completed. The amount (g) of discharged purge waste was measured using a balance, and the replacement performance was evaluated using the following evaluation criteria.
The replacement was completed when the external color of the molten purge waste discharged from the die during replacement changed from the color of the cleaning composition to colorless and transparent.
+++: The amount of purge waste discharged is less than 30 g ++: The amount of purge waste discharged is 30 g or more and less than 80 g. +: The amount of purge waste discharged is 80 g or more.

(6) Thermal stability (MFR change rate, standard deviation)
The MFR of the pellets of the resin compositions obtained in Examples and Comparative Examples was measured under the following conditions: (1) 220° C. and a load of 10 kg; (2) 240° C. and a load of 10 kg. Using the obtained average value, the MFR change rate was calculated using the following formula. Furthermore, the standard deviation under each condition obtained in the same measurement was also used as an index of thermal stability.
MFR change rate [%] = MFR value under the condition (2) above / MFR value under the condition (1) above x 100 The lower the MFR change rate above, the more similar cleaning effects can be expected in various temperature ranges. , and has excellent thermal stability. Furthermore, the lower the standard deviation, the better the thermal stability during residence at each temperature.

The resin composition for cleaning agents of the present invention not only exhibits excellent cleaning performance, but also has excellent easy displacement and thermal stability, and is particularly suitable for resin processing machines such as injection molding and extrusion molding of thermoplastic resins. Useful as a cleaning agent.

Claims (8)

Containing at least (A) a polyethylene resin and (B) a crosslinked polyethylene resin,
The mass proportion of the (A) polyethylene resin is 90 to 10 parts by mass to the total of 100 parts by mass of the (A) polyethylene resin and the (B) crosslinked polyethylene resin, and the (B) crosslinked polyethylene resin A resin composition for a cleaning agent for resin processing machines, wherein the mass proportion of the resin is 10 to 90 parts by mass, and the following (1) or (2) is provided.
(1) Melt mass flow rate (MFR 220°C, load 10 kg) is 0.1 to 2.0 g/10 min. (2) Polyethylene resin and crosslinked polyethylene resin contained in the resin composition for cleaning agent for resin processing machines. The ratio of the total of polyethylene resin and crosslinked polyethylene resin with a molecular weight of 3,000,000 or more determined by gel permeation chromatography (GPC, mobile phase: o-dichlorobenzene, standard material: polystyrene) to the total is 1. 8% or more The resin composition for a cleaning agent for resin processing machines according to claim 1, having a gel fraction (according to JIS K6796) of 0.3 to 4.5%. The resin processing machine according to claim 1 or 2, wherein the polyethylene resin (A) is linear low density polyethylene with an MFR (190° C., load 2.16 kg) of 0.1 to 1.5 g/10 minutes. Resin composition for cleaning agents. The resin composition for a cleaning agent for resin processing machines according to claim 1 or 2, wherein the crosslinked polyethylene resin (B) has a gel fraction (according to JIS K6796) of 10 to 45%. The resin composition for a cleaning agent for resin processing machines according to claim 1 or 2, wherein the crosslinked polyethylene resin (B) has an MFR (220° C., load 10 kg) of 0.01 to 0.50 g/10 minutes. The resin composition for a cleaning agent for resin processing machines according to claim 1 or 2, wherein the crosslinked polyethylene resin (B) is a crosslinked polyethylene resin crosslinked by peroxide or electron beam crosslinking. The resin composition for a cleaning agent for resin processing machines according to claim 1 or 2, wherein the crosslinked polyethylene resin (B) is a crosslinked polyethylene resin obtained by a manufacturing method including recycling or volume reduction. A method for cleaning resin processing machines, comprising using the resin composition for cleaning agents for resin processing machines according to claim 1 or 2.