Resin composition for cleaning molding machine

Abstract

The present disclosure provides a resin composition for cleaning a molding machine, which is excellent in terms of workability while exhibiting cleaning properties equal to or higher than those of a conventional one.　A resin composition for cleaning a molding machine according to the present invention is characterized by comprising an acrylonitrile-styrene copolymer (AS) resin, a rubber component, and an aliphatic surfactant and / or an aromatic surfactant, and is also characterized in that the content of the rubber component is 3-15 parts by mass with respect to 100 parts by mass of the AS resin. In addition, it is preferable that the content of a constituent unit derived from a vinyl cyanide compound in the AS resin is 34 mass% or less.

Description

Resin composition for cleaning molding machines

[0001] This disclosure relates to a resin composition for cleaning molding machines. This application claims priority from Japanese Patent Application No. 2024-063514, filed April 10, 2024, the contents of which are incorporated herein by reference.

[0002] Injection molding machines and extrusion molding machines are primarily used for molding thermoplastic resins. After use, these molding machines leave behind the resin, additives, and resin degradation products generated during molding. If the next resin molding process is performed while these residues remain, they will be mixed into the molded product, degrading the appearance of the molded product and reducing the expected resin properties. Therefore, pellet-shaped cleaning agents are generally used before the next molding process (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2008-201975

[0004] However, conventional cleaning agents such as those described in Patent Document 1 have a problem in that resin powder is generated when pellets come into contact with each other during pellet production or transportation. The generated resin powder reduces workability, so there has been a demand for reducing the resin powder and improving workability. Note that the resin powder in this disclosure refers to powdery resin generated when pellets collide with each other during transportation, etc.

[0005] The present disclosure is intended to solve the above-mentioned problems, and an object of the present disclosure is to provide a resin composition for cleaning molding machines that exhibits cleaning properties equal to or better than conventional ones and has excellent workability.

[0006] The inventors of the present disclosure have discovered that a resin composition for cleaning molding machines, which comprises an acrylonitrile-styrene copolymer (AS) resin, a rubber component, and an aliphatic surfactant and / or an aromatic surfactant, in which the content of the rubber component is within a specific range, and in which the amount of resin powder generated during production or transportation is a certain amount or less, exhibits cleaning performance equal to or better than conventional compositions while also having excellent workability.

[0007] That is, the present disclosure provides a resin composition for cleaning molding machines, which comprises an acrylonitrile-styrene copolymer (AS) resin, a rubber component, and an aliphatic surfactant and / or an aromatic surfactant, in which the content of the rubber component is 3 to 15 parts by mass per 100 parts by mass of the AS resin.

[0008] The content of structural units derived from vinyl cyanide compounds in the AS resin is preferably 34% by mass or less, which makes it easy to suppress discoloration while maintaining an appropriate viscosity of the resin composition for cleaning molding machines.

[0009] The content of the aliphatic surfactant and the aromatic surfactant is preferably 0.5 to 10 parts by mass per 100 parts by mass of the AS-based resin, which makes it easier to prevent metering errors during injection molding while also improving the resin's cleanability and self-discharging properties.

[0010] The resin composition for cleaning molding machines according to the present disclosure exhibits cleaning properties equal to or better than conventional ones and is also excellent in workability.

[0011] [Resin Composition for Cleaning Molding Machines] The resin composition for cleaning molding machines according to the present disclosure (hereinafter, may be referred to as the "resin composition of the present disclosure") comprises an acrylonitrile-styrene copolymer (AS) resin, a rubber component, and an aliphatic surfactant and / or an aromatic surfactant. The content of the rubber component is 3 to 15 parts by mass per 100 parts by mass of the AS resin, and therefore the amount of resin powder is sufficiently reduced, resulting in excellent workability.

[0012] When 1000 g of the resin composition of the present disclosure is placed in an antistatic polyethylene bag and manually shaken up and down and left and right a total of 100 times while containing air, the amount of resin powder generated is 1 g or less, more preferably 0.7 g or less, and even more preferably 0.5 g or less. By having the amount of resin powder be 1 g or less, excellent workability can be achieved.

[0013] The amount of the resin composition of the present disclosure required to clean a PC / ABS resin, as measured under the conditions of the examples described below, is preferably 700 g or less, more preferably 600 g or less. When the amount of the resin composition required to clean a PC / ABS resin is 700 g or less, the resin can be efficiently discharged from the molding machine, and sufficient cleanability can be achieved.

[0014] Similarly, the amount required to wash the ABS resin, measured under the conditions of the Examples described below, is preferably 700 g or less, more preferably 600 g or less, and even more preferably 500 g or less. When the amount of resin composition required to wash the ABS resin is 700 g or less, the resin can be efficiently discharged from the molding machine, and sufficient washability can be exhibited.

[0015] Furthermore, when the self-discharging property is evaluated under the conditions of the examples described below, the amount discharged is preferably within 400 g, more preferably within 350 g, and even more preferably within 300 g.

[0016] The resin composition of the present disclosure preferably has an MFR (melt flow rate) of 3 to 40 g / 10 min, more preferably 5 to 35 g / 10 min, and even more preferably 8 to 25 g / 10 min, measured at a temperature of 240°C and a nominal load of 5 kg. When the MFR is 3 g / 10 min or higher, the resin composition is likely to exhibit fluidity. When the MFR is 40 g / 10 min or lower, the resin composition is likely to exhibit heat resistance and mechanical strength.

[0017] (Acrylonitrile-styrene copolymer (AS)-based resin) The resin composition of the present disclosure contains an acrylonitrile-styrene copolymer (AS)-based resin, and preferably contains it as a main component. The AS-based resin is a thermoplastic copolymer resin obtained by copolymerizing a vinyl cyanide compound and an aromatic vinyl compound. Only one type of AS-based resin may be used, or two or more types may be used.

[0018] Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile, with acrylonitrile being particularly preferred.

[0019] Examples of the aromatic vinyl compound include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, vinylnaphthalene, methoxystyrene, monobromostyrene, dibromostyrene, fluorostyrene, and tribromostyrene, with styrene and α-methylstyrene being particularly preferred.

[0020] The AS resin may contain, as a constituent monomer, a vinyl compound other than the vinyl cyanide compound and the aromatic vinyl compound. Examples of the other vinyl compounds include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; (meth)acrylic acids such as acrylic acid and methacrylic acid; α,β-unsaturated carboxylic acids such as maleic anhydride; maleimides such as N-phenylmaleimide, N-methylmaleimide, and N-cyclohexylmaleimide; and glycidyl group-containing monomers such as glycidyl (meth)acrylate.

[0021] Specifically, the AS-based resin is preferably a copolymer resin containing acrylonitrile-derived structural units and styrene-derived structural units, and more preferably a copolymer resin consisting of acrylonitrile-derived structural units and styrene-derived structural units. That is, the AS-based resin is preferably an AS resin.

[0022] The AS-based resin was dissolved in CHCl ３ The intrinsic viscosity of the composition when melted in a solvent is not particularly limited, but is preferably 0.61 to 1.21, and more preferably 0.82 to 1.07. When the intrinsic viscosity is 0.61 or more, cleaning properties can be exhibited, and when the intrinsic viscosity is 1.21 or less, self-draining properties can be improved.

[0023] The content of the vinyl cyanide compound-derived structural units in the AS resin is preferably 34% by mass or less, more preferably 31% by mass or less, and even more preferably 29% by mass or less, based on the total amount (100% by mass) of the AS resin. By having the vinyl cyanide compound-derived structural units be 34% by mass or less, the viscosity of the AS resin can be kept appropriate while discoloration can be easily suppressed. While the lower limit is not particularly limited, it is preferably 22% by mass or more, and more preferably 23% by mass or more.

[0024] The AS resin preferably has an MFR (melt flow rate) of 9 to 70 g / 10 min, more preferably 15 to 40 g / 10 min, measured at a temperature of 220°C and a nominal load of 10 kg. An MFR of 9 g / 10 min or more facilitates fluidity. Furthermore, an MFR of 70 g / 10 min or less facilitates heat resistance and mechanical strength.

[0025] The content of the aromatic vinyl compound-derived structural units in the AS resin is preferably 66 to 78% by mass, and more preferably 69 to 77% by mass, relative to the total amount (100% by mass) of the AS resin. When the content of the aromatic vinyl compound-derived structural units is within this range, the viscosity of the AS resin can be kept appropriate and discoloration can be easily suppressed.

[0026] When the AS resin contains the structural units derived from the other vinyl compounds, the content thereof is preferably 10% by mass or less, more preferably 1% by mass or less, based on the total amount (100% by mass) of the AS resin. By keeping the content of the structural units derived from the other vinyl compounds at 10% by mass or less, the AS resin can more easily exhibit its functions as an AS resin.

[0027] The content of the AS-based resin is preferably more than 50% by mass, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the total amount (100% by mass) of the resin composition of the present disclosure. By having the AS-based resin content exceed 50% by mass, the resin can function as the main component of the resin composition of the present disclosure. The upper limit is not particularly limited, but is preferably 97% by mass or less, more preferably 95% by mass or less.

[0028] The AS resin can be prepared by known or commonly used methods, such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization.

[0029] (Rubber Component) The resin composition of the present disclosure contains a rubber component. By containing the rubber component in the resin composition of the present disclosure, when the resin composition of the present disclosure is molded into pellets, the cross section of the pellets can be made smooth, and the amount of resin powder when the pellets come into contact with each other can be reduced. Only one type of rubber component may be used, or two or more types may be used.

[0030] As the rubber component, a rubber component alone may be used, or a rubber-containing resin may be used. Among these, it is preferable to use a rubber-containing resin from the viewpoint of exhibiting compatibility with the AS-based resin, etc., and it is more preferable that the rubber-containing resin is a styrene-based resin containing a rubber component. In the present disclosure, even if the resin contains a rubber component in part, such as the rubber-containing resin, the entire resin is treated as the rubber component.

[0031] Examples of the rubber component include diene rubber, urethane rubber, silicone rubber, polysulfide rubber, etc. Among these, diene rubber is preferred, and examples of the diene rubber include natural rubber, polyisoprene rubber, polybutadiene rubber, butyl rubber, chloroprene rubber, and modified rubber (epoxidized natural rubber, hydrogenated natural rubber, hydrogenated butadiene-acrylonitrile copolymer rubber, etc.).

[0032] Further, examples of the rubber component contained in the rubber-containing resin include diene copolymers such as polybutadiene, polyisoprene, and random copolymers and block copolymers of styrene-butadiene, acrylonitrile-butadiene copolymers, and copolymers of (meth)acrylic acid alkyl esters and butadiene; copolymers of ethylene and α-olefins such as ethylene-propylene random copolymers and block copolymers, and ethylene-butene random copolymers and block copolymers; copolymers of ethylene and unsaturated carboxylic acid esters such as ethylene-methacrylate copolymers and ethylene-butyl acrylate copolymers; Examples of such rubbers include copolymers with aliphatic vinyl, ethylene-propylene-hexadiene copolymers and other ethylene-propylene-non-conjugated diene polymers, acrylic rubbers such as polybutyl acrylate, poly(2-ethylhexyl acrylate), and copolymers of butyl acrylate and 2-ethylhexyl acrylate, as well as silicone rubbers such as polyorganosiloxane rubber, IPN rubbers consisting of a polyorganosiloxane rubber component and a polyalkyl(meth)acrylate rubber component (i.e., rubbers having a structure in which the two rubber components are inseparably intertwined), and IPN rubbers consisting of a polyorganosiloxane rubber component and a polyisobutylene rubber component. Among these, polybutadiene, polyisoprene, and diene copolymers are preferred, with polybutadiene being particularly preferred.

[0033] Examples of the styrene-based resin containing the rubber component include HIPS resin, MS resin, ABS resin, AES resin, ASA resin, MBS resin, MABS resin, MAS resin, SMA resin, and styrene-based thermoplastic elastomer (e.g., (hydrogenated) styrene-butadiene-styrene copolymer, (hydrogenated) styrene-isoprene-styrene copolymer, etc.). Among these, ABS resin is preferred from the viewpoint of compatibility with the AS-based resin.

[0034] When a rubber-containing resin is included as the rubber component, the content of the rubber component in the total amount (100% by mass) of the rubber-containing resin is preferably 18 to 80% by mass, more preferably 35 to 70% by mass, and even more preferably 40 to 60% by mass. A rubber component content of 18% by mass or more facilitates reducing the amount of resin powder. Furthermore, a rubber component content of 80% by mass or less facilitates compatibility with other resin components contained in the resin composition of the present disclosure.

[0035] Furthermore, when an ABS resin is contained as the rubber component, the content of acrylonitrile-derived structural units in the total amount (100% by mass) of the ABS resin is preferably 28% by mass or less, more preferably 27% by mass or less, and even more preferably 26% by mass or less. By having the content of acrylonitrile-derived structural units be 28% by mass or less, discoloration of the ABS resin can be easily suppressed while maintaining a suitable viscosity. Furthermore, although there is no particular limitation on the lower limit, it is preferably 18% by mass or more, more preferably 23% by mass or more.

[0036] The content of the rubber component is 3 to 15 parts by mass, preferably 4 to 14 parts by mass, and more preferably 5 to 10 parts by mass, per 100 parts by mass of the AS-based resin. By including 3 parts by mass or more of the rubber component, the amount of resin powder can be reduced. Furthermore, by including 15 parts by mass or less, cleanability can be maintained.

[0037] The content of the rubber component in the total amount (100% by mass) of the resin composition of the present disclosure is preferably 2 to 13% by mass, and more preferably 3 to 12% by mass. By including 2% by mass or more of the rubber component, the amount of resin powder can be reduced. By including 13% by mass or less, cleanability can be maintained.

[0038] When the rubber component contains an ABS resin, the reduced viscosity of the ABS resin is preferably 0.2 to 0.8%, more preferably 0.3 to 0.7%, and even more preferably 0.4 to 0.6%.

[0039] The reduced viscosity was measured at 30°C after dissolving the ABS resin in acetone, separating it into an acetone-soluble fraction and an acetone-insoluble fraction, volatilizing the acetone from the acetone-soluble fraction, and dissolving the resulting fraction in dimethylformamide to prepare a 0.4 g / 100 ml solution.

[0040] (Aliphatic surfactant and / or aromatic surfactant) The resin composition of the present disclosure contains an aliphatic surfactant and / or an aromatic surfactant. The surfactant is a component added to the resin composition of the present disclosure to enhance its cleaning properties while exhibiting self-draining properties. As the aliphatic surfactant and / or the aromatic surfactant, either one may be used alone, or two or more of either may be used. Furthermore, the aliphatic surfactant and the aromatic surfactant may each be used alone, or two or more of them may be used.

[0041] Examples of the aliphatic surfactant include nonionic aliphatic surfactants and anionic aliphatic surfactants.

[0042] Examples of the nonionic aliphatic surfactants include sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyalkylene alkyl ethers, and polyoxyalkylene fatty acid esters.

[0043] Examples of the sorbitan fatty acid esters include sorbitan monooleate, sorbitan monostearate, sorbitan monoisostearate, sorbitan monopalmitate, sorbitan monolaurate, sorbitan trioleate, sorbitan tristearate, sorbitan sesquistearate, sorbitan sesquioleate, sorbitan sesquiisostearate, and sorbitan coconut oil fatty acid. Examples of alkylene oxide adducts of sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monoisostearate, polyoxyethylene sorbitan monococonut oil fatty acid, polyoxyethylene sorbitan tristearate, and polyoxyethylene sorbitan trioleate.

[0044] The glycerin fatty acid esters include both monoglycerin fatty acid esters and polyglycerin fatty acid esters. Examples of monoglycerin fatty acid esters include glyceryl monocaprylate, glyceryl monocaprate, glyceryl monolaurate, glyceryl monomyristate, glyceryl monopalmitate, glyceryl monostearate, glyceryl monoisostearate, glyceryl monobehenate, glyceryl monooleate, glyceryl monoerucate, glyceryl sesquioleate, glyceryl distearate, glyceryl diisostearate, and glyceryl diarachate. Examples of the polyglycerol fatty acid esters include polyglycerol fatty acid esters having a degree of polymerization of 2 to 10, such as diglyceryl monocaprylate, decaglyceryl monocaprylate, hexaglyceryl monocaprate, tetraglyceryl monolaurate, hexaglyceryl monolaurate, decaglyceryl monolaurate, poly(4-10)glyceryl monolaurate, decaglyceryl monomyristate, decaglyceryl monostearate, decaglyceryl monoisostearate, poly(2-10)glyceryl monostearate, diglyceryl monooleate, hexaglyceryl monooleate, diglyceryl sesquioleate, poly(2-10)glyceryl diisostearate, poly(6-10)glyceryl distearate, diglyceryl triisostearate, and poly(10)glyceryl tristearate. Examples of alkylene oxide adducts of glycerin fatty acid esters include polyoxyethylene glyceryl monostearate and polyoxyethylene glyceryl monooleate.

[0045] The polyoxyalkylene alkyl ethers include both monooxyalkylene alkyl ethers and polyoxyalkylene alkyl ethers, such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxypropylene cetyl ether, polyoxypropylene isocetyl ether, polyoxypropylene stearyl ether, and polyoxypropylene oleyl ether.

[0046] The polyoxyalkylene fatty acid esters include both monooxyalkylene fatty acid esters and polyoxyalkylene fatty acid esters, and specific examples of the polyoxyalkylene fatty acid esters include ethylene glycol mono- and di-fatty acid esters, diethylene glycol mono- and di-fatty acid esters, polyethylene glycol mono- and di-fatty acid esters, propylene glycol mono- and di-fatty acid esters, and polypropylene glycol mono- and di-fatty acid esters.

[0047] Specific examples of the ethylene glycol mono- and di-fatty acid esters include ethylene glycol monolaurate, ethylene glycol monopalmitate, ethylene glycol monostearate, ethylene glycol dilaurate, ethylene glycol dipalmitate, ethylene glycol distearate, etc. Of these, ethylene glycol distearate is more preferred.

[0048] Examples of the anionic aliphatic surfactant include alkyl or alkenyl ether sulfates, alkyl or alkenyl sulfates, α-olefin sulfonates having 8 to 20 carbon atoms, alkanesulfonates, alkyl or alkenyl ether carboxylates, and alkali metal salts of saturated or unsaturated fatty acids having 12 to 20 carbon atoms. Of these, alkanesulfonates are preferred.

[0049] Examples of the alkane sulfonates include sodium octyl sulfonate, sodium ethylhexyl sulfonate, sodium undecyl sulfonate, sodium dodecyl sulfonate, sodium dodecyl sulfonate, sodium hexadecyl sulfonate, and sodium octadecyl sulfonate. The salt may be a potassium salt, an ammonium salt, or the like, in addition to a sodium salt. Of these, the alkane sulfonate is preferably sodium alkane sulfonate, and more preferably a mixture of sodium alkanesulfonates having 10 to 18 carbon atoms.

[0050] The content of the aliphatic surfactant is preferably 50 to 90% by mass, more preferably 55 to 85% by mass, and even more preferably 60 to 70% by mass, based on the total amount (100% by mass) of surfactants used. By having the content of the aliphatic surfactant relative to the total amount of surfactants within the above range, it becomes easy to exhibit cleaning properties for various resins.

[0051] The content of the aliphatic surfactant is preferably 0.5 to 10 mass %, more preferably 2 to 8 mass %, relative to the total amount (100 mass %) of the resin composition of the present disclosure.

[0052] Examples of the aromatic surfactant include nonionic aromatic surfactants and anionic aromatic surfactants.

[0053] Examples of the nonionic aromatic surfactants include polyoxyethylene bisphenol A ether, polyoxyethylene bisphenol F ether, polyoxypolycyclic phenyl ether, polyoxyethylene phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene cumyl phenyl ether, polyoxyethylene tribenzyl phenyl ether, and polyoxyethylene benzyl ether.

[0054] Examples of the anionic aromatic surfactant include alkylbenzene sulfonates and aromatic condensed phosphate esters, and aromatic condensed phosphate esters are particularly preferred.

[0055] As the alkylbenzenesulfonate, for example, a linear alkylbenzenesulfonate having an alkyl group with 8 to 20 carbon atoms or less can be used, and specific examples thereof include sodium decylbenzenesulfonate, sodium undecylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium tridecylbenzenesulfonate, sodium tetradecylbenzenesulfonate, sodium pentadecylbenzenesulfonate, sodium hexadecylbenzenesulfonate, etc. In addition to the sodium salt, the salt may also be a potassium salt, an ammonium salt, etc.

[0056] Examples of the aromatic condensed phosphate ester include resorcinol bisdiphenyl phosphate, bisphenol A bis(diphenyl phosphate), and resorcinol bisdixylenyl phosphate, with resorcinol bisdixylenyl phosphate being preferred.

[0057] The content of the aromatic surfactant is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, and even more preferably 20 to 40% by mass, relative to the total amount (100% by mass) of surfactants used. When the content of the aromatic surfactant relative to the total amount of surfactants is within the above range, cleaning properties can be easily exhibited against various resins.

[0058] The content of the aromatic surfactant is preferably 0.5 to 5 mass %, more preferably 1 to 4 mass %, relative to the total amount (100 mass %) of the resin composition of the present disclosure.

[0059] The total content of the aliphatic surfactant and the aromatic surfactant is preferably 0.5 to 10% by mass, more preferably 1 to 9% by mass, and even more preferably 3 to 8% by mass, relative to the total amount (100% by mass) of the resin composition of the present disclosure. By setting the content of the aliphatic surfactant and the aromatic surfactant to 0.5% by mass or more, the resin can be easily cleaned and self-draining. Furthermore, by setting the content to 10% by mass or less, it is easy to prevent metering errors during injection molding. When the resin composition of the present disclosure contains only one of the aliphatic surfactant and the aromatic surfactant, the content preferably satisfies the above range.

[0060] The resin composition of the present disclosure preferably contains an inorganic filler. By containing the inorganic filler, the viscosity of the resin composition of the present disclosure can be adjusted while the cleaning properties can be exhibited due to the polishing effect of the inorganic filler. Only one type of the inorganic filler may be used, or two or more types may be used.

[0061] The inorganic filler may be either a natural product or an artificially synthesized product, and examples of the inorganic filler include talc, mica, wollastonite, xonotlite, kaolin clay, montmorillonite, bentonite, sepiolite, imogolite, sericite, lawsonite, smectite, calcium carbonate, magnesium carbonate, titanium oxide, aluminum hydroxide, magnesium hydroxide, zeolite, diatomaceous earth, glass powder, glass spheres, and shirasu balloons.

[0062] The shape of the inorganic filler is not particularly limited and may be any shape (plate-like, needle-like, granular, fibrous, etc.). These inorganic fillers may also be calcined or may have been subjected to a surface hydrophobic treatment using a silane coupling agent, titanate coupling agent, or the like. Furthermore, the volume-average particle size is preferably 0.1 to 50 μm, and more preferably 1 to 30 μm. The volume-average particle size can be measured by a laser diffraction scattering method.

[0063] The content of the inorganic filler is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, relative to the total amount (100% by mass) of the resin composition of the present disclosure. By setting the content of the inorganic filler to 0.1% by mass or more, it becomes easier to improve the cleanability. Furthermore, by setting the content to 10% by mass or less, it becomes easier to achieve an appropriate viscosity for the resin composition of the present disclosure.

[0064] Furthermore, it is preferable that the resin composition of the present disclosure further contains a phosphate and / or a condensed phosphate. By containing a phosphate and / or a condensed phosphate, the cleaning properties and replacement properties can be further improved. As the phosphate and / or the condensed phosphate, only one kind of either one may be used, or two or more kinds of either one may be used. Furthermore, the phosphate and the condensed phosphate may each be used alone, or two or more kinds may be used.

[0065] Examples of the phosphate salt include sodium phosphate and disodium hydrogen phosphate.

[0066] Examples of the condensed phosphate include sodium pyrophosphates such as disodium dihydrogen pyrophosphate and sodium dihydrogen pyrophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, sodium pentapolyphosphate, and sodium metaphosphate.

[0067] The content of the phosphate and the condensed phosphate is preferably 0.1 to 10 mass %, more preferably 0.5 to 5 mass %, relative to the total amount (100 mass %) of the resin composition of the present disclosure. When the content of the phosphate and the condensed phosphate is within the above range, cleaning properties and replacement properties can be easily exhibited.

[0068] The resin composition of the present disclosure may contain other components in addition to the above-mentioned components. Examples of the other components include flame retardants, anti-dripping agents, dyes and pigments, heat stabilizers, UV absorbers, fluorescent brighteners, lubricants, processing aids, dispersants, mold release agents, thickeners, antioxidants, antistatic agents, and foaming agents. Only one type of the other components may be used, or two or more types may be used.

[0069] The content of the above other components is preferably 10% by mass or less, more preferably 5% by mass or less, and may be 0% by mass, relative to the total amount (100% by mass) of the resin composition of the present disclosure.

[0070] The method for producing the resin composition of the present disclosure is not particularly limited, but a preferred production method includes a production method comprising the steps of melt-kneading the AS-based resin, the rubber component, the surfactant, and the phosphate, condensed phosphate, inorganic filler, and other components that are blended as needed using a melt-kneading device such as a kneader, extruder, or Banbury mixer, extruding the resulting melt-kneaded mixture into strands, and then molding them into pellets. As the melt-kneading device, an extruder is preferred from the viewpoint of being able to sufficiently knead raw materials such as thermoplastic resins.

[0071] When blending and melt-kneading the components, commonly used devices can be used, for example, premixers such as tumblers, ribbon blenders, and supermixers, and melt-kneading devices such as gravimetric feeders, single-screw extruders, twin-screw extruders, and co-kneaders. When melt-kneading, it is desirable to perform open devolatilization, in which devolatilized material is removed from an open port (vent) at normal pressure, and, if necessary, reduced-pressure devolatilization, in which devolatilized material is removed from an open port (vent) by reducing the pressure.

[0072] The temperature in the step of pelletizing the strands into pellets is preferably 40 to 150° C., more preferably 50 to 120° C. Even when the resin composition of the present disclosure is rapidly cooled, it can be molded to have a smooth cross section, thereby reducing resin powder generated by pellets rubbing against each other.

[0073] A method for cleaning a molding machine using the resin composition of the present disclosure includes charging the resin composition of the present disclosure into the cylinder of a resin molding machine, heating the resin composition of the present disclosure to plasticize (melt) and maintain it, and then discharging the plasticized resin composition of the present disclosure from the cylinder of the resin molding machine. In particular, since the resin composition of the present disclosure has a reduced amount of resin powder, it is easy to work with when charging the resin composition into the cylinder.

[0074] Applicable resin molding machines include, for example, injection molding machines and extrusion molding machines, but are not particularly limited to these as long as they have a cylinder for heating, melting, and kneading the resin. That is, the resin composition of the present disclosure can be widely applied to known resin molding machines. When heating the resin composition of the present disclosure, the cylinder temperature of the resin molding machine is preferably 180°C or higher, more preferably 200°C or higher. The upper limit of the heating temperature is not particularly limited, but is usually about 400°C.

[0075] The resin composition of the present disclosure can efficiently clean and discharge residual resin materials contained in the resin itself or in molding materials such as dyes and pigments that remain in the molding machine after a predetermined operation in the extruder molding machine or injection molding machine. Therefore, the resin composition of the present disclosure can be suitably used as a cleaning resin composition for cleaning the inside of a thermoplastic resin molding machine. In other words, the resin composition of the present disclosure is preferably a cleaner for an extruder molding machine or an injection molding machine.

[0076] Furthermore, the resin composition of the present disclosure can be suitably used for resins to be cleaned, such as PA, PMMA, PLA, ABS, AS, PVC, PVDF, TPU, PC, PET, PBT, and POM, as well as resin compositions containing any of the above resins as a main component (preferably 50% by mass or more).

[0077] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Each configuration and combination thereof in each embodiment is an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope of the present disclosure. Furthermore, each invention according to this disclosure is not limited by the embodiments or the following examples, but is limited only by the scope of the claims.

[0078] Hereinafter, one embodiment of the present disclosure will be described in more detail based on examples.

[0079] Examples 1 to 3, Comparative Examples 1 and 2 The components shown in Table 1 were mixed (mixing time: 120 seconds, mixing speed: 120 rpm) in a tumbler blender (trade name "SFC-50", manufactured by Kawata Corporation) and then molded into pellets using an extruder (trade name "TEX-30", manufactured by The Japan Steel Works, Ltd.) under the following conditions: nozzle diameter: 32 mm, cylinder temperatures C1: 210°C, C2 to C8: 230°C (C1: upstream side, C8: downstream side), die temperature: 240°C, screw rotation speed: 200 rpm, and discharge rate: 20 kg / h, to produce resin compositions for cleaning molding machines of Examples 1 to 3 and Comparative Examples 1 and 2. The MFRs of the resin compositions for cleaning molding machines in Example 1, Example 2, and Example 3, measured at a temperature of 240°C and a nominal load of 5 kg, were 13 g / 10 min, 15 g / 10 min, and 18 g / 10 min, respectively. The MFRs of the resin compositions for cleaning molding machines in Comparative Example 1 and Comparative Example 2 were 25 g / 10 min and 8.0 g / 10 min, respectively.

[0080] Each component used in Table 1 is described in detail below. Styrene-acrylonitrile copolymer: content of structural units derived from vinyl cyanide compounds: 28% by mass, MFR (measurement temperature: 220°C, nominal load: 10 kg): 9.7 g / 10 min, intrinsic viscosity: 1.07 Styrene-acrylonitrile-butadiene copolymer: content of structural units derived from aromatic vinyl compounds: 45% by mass, content of structural units derived from vinyl cyanide compounds: 15% by mass, content of structural units derived from rubber components: 40% by mass, reduced viscosity of acetone solubles: 0.5%, intrinsic viscosity: 0.45 Sodium alkane sulfonate: (trade name "WeyClean SAS93", manufactured by Clariant Japan K.K.) Sodium dodecylbenzenesulfonate: (trade name "Newlex Soft 60-N", manufactured by NOF Corporation) Ethylene glycol distearate: (trade name "Emanon 3201M-V", manufactured by Kao Corporation) Aromatic condensed phosphate ester: (trade name "PX-200", manufactured by Daihachi Chemical Industry Co., Ltd.) Sodium phosphate: (trade name "disodium phosphate (anhydrous)", manufactured by Taihei Chemical Industry Co., Ltd.) Talc: (trade name "Talc FU-51", manufactured by Hayashi Kasei Co., Ltd.)

[0081] [Evaluation] The resin compositions for cleaning molding machines prepared in the Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

[0082] (1) Amount of Resin Powder Generated 1,000 g of each of the resin compositions for cleaning molding machines of Examples 1 to 3 and Comparative Examples 1 and 2 was placed in an antistatic polyethylene bag, and the bag was stirred by manually shaking it up and down and left and right a total of 100 times while the bag contained air. Thereafter, the entire contents of the antistatic polyethylene bag was passed through a 4.0 mm sieve, and the amount (g) of resin powder sieved out was measured.

[0083] (2)-1. Cleanability for PC / ABS 500 g of PC / ABS resin (trade name "Novalloy S1100", manufactured by Daicel Miraize Co., Ltd.) was first placed in an injection molding machine (trade name "2000i-100B", manufactured by Fanuc Corporation, injection speed 100 mm / sec, rotation speed 100 rpm, nozzle temperature 260°C-cylinder front 270°C-cylinder middle 260°C-cylinder rear 250°C, back pressure 0.3 MPa, stroke 50 mm) and then discharged.

[0084] Next, the stroke was adjusted to 40 mm, and 100 g of each of the resin compositions for cleaning molding machines of Examples 1 to 3 and Comparative Examples 1 and 2 was charged into the injection molding machine, up to a maximum of 1,000 g, to replace the PC / ABS resin. The cleaning was considered complete when the color of the PC / ABS resin was no longer visible to the naked eye, and the mass (g) of the cleaning resin composition required to complete the cleaning was measured.

[0085] (2)-2. Cleanability for ABS The cleanability for ABS resin was measured in the same manner as in (2)-1, except that black ABS resin pellets (product name "Cevian V 500", product of Daicel Miraize Co., Ltd.) were used instead of PC / ABS resin (product name "Novalloy S1100", product of Daicel Miraize Co., Ltd.), and the nozzle temperature of the injection molding machine was 220°C, 230°C at the front of the cylinder, 220°C at the middle of the cylinder, and 210°C at the rear of the cylinder.

[0086] (3) Self-draining property The resin compositions for cleaning molding machines of Examples 1 to 3 and Comparative Examples 1 and 2 were discharged under the same conditions as those used to evaluate the cleaning property for ABS described above, and then injection molding was carried out using a transparent AS resin (product name "Cevian 050SF", manufactured by Daicel Miraize Co., Ltd.) at a cylinder temperature of 230°C. If no residue was found within 400 g, the composition was evaluated as "Good", and if any residue remained even after using more than 400 g, the composition was evaluated as "Poor".

[0087]

[0088] The resin compositions for cleaning molding machines of Examples 1 to 3 were confirmed to have cleaning properties equal to or better than those of conventional products, while producing less resin powder and exhibiting excellent workability. On the other hand, when no rubber component was contained, a large amount of resin powder was generated, resulting in poor workability (Comparative Example 1). Furthermore, when the rubber component was contained in excess relative to the AS-based resin, poor cleanability was confirmed (Comparative Example 2).

Claims

1. A resin composition for cleaning molding machines, comprising an acrylonitrile-styrene copolymer (AS) resin, a rubber component, and an aliphatic surfactant and / or an aromatic surfactant, wherein the content of the rubber component is 3 to 15 parts by mass per 100 parts by mass of the AS resin.

2. A resin composition for cleaning molding machines according to claim 1, wherein the content of structural units derived from vinyl cyanide compounds in the AS-based resin is 34% by mass or less.

3. A resin composition for cleaning molding machines according to claim 1 or 2, wherein the content of the aliphatic surfactant and the aromatic surfactant is 0.5 to 10 parts by mass per 100 parts by mass of the AS-based resin.

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