Resin composition for cleaning, and method for cleaning a resin molding machine.

Abstract

The present invention provides a cleaning resin composition for cleaning resin compositions that are molded in a relatively low temperature range, and which exhibits good cleaning performance. [Solution] The cleaning resin composition that solves the above problem comprises a thermoplastic resin containing an olefin resin, an inorganic powder containing calcium carbonate with an average particle size of 0.7 μm or more and 6.0 μm or less, as measured by the air permeation method in accordance with JIS M8511:2014, a sulfate ester surfactant, and a hydrogenated petroleum resin. The mass ratio of the thermoplastic resin to the inorganic powder is 50:50 to 10:90, the amount of the sulfate ester surfactant is 0.2% by mass or more and 5.0% by mass or less, and the amount of the hydrogenated petroleum resin is 0.5% by mass or more and 3.0% by mass or less.

Description

Technical Field

[0001] The present invention relates to a cleaning resin composition for cleaning a resin molding machine, and a method for cleaning a resin molding machine using the same.

Background Art

[0002] Conventionally, various resin compositions have been molded by a resin molding machine (hereinafter, also simply referred to as a "processing machine"), and many products have been manufactured. In this processing machine, when changing the type of the resin composition used for molding, it is necessary to clean the inside of the processing machine. Also, when using the processing machine for a long period of time, even when manufacturing products with the same resin composition, it is preferable to perform regular cleaning. If the resin composition used previously remains in the processing machine, it may become carbide (char) of the residual component, and this may be mixed into subsequent products. In addition, the residual component may cause defects in the appearance or performance of subsequent products. However, it is not efficient to disassemble the processing machine and clean all parts. Therefore, it is common to supply a cleaning resin composition to the processing machine and clean the processing machine by flowing this through the processing machine.

[0003] The above cleaning resin composition generally contains a normal resin and, if necessary, a filler. The type of resin in the cleaning resin composition is appropriately selected according to the processing temperature of the resin composition to be cleaned, the type of resin contained in the object to be cleaned, and the like. Conventionally, many cleaning resin compositions for objects to be cleaned with a relatively high processing temperature, such as polycarbonate and engineering plastics, have been developed. On the other hand, for cleaning resin compositions for objects to be cleaned with a relatively low processing temperature, such as olefin resins, there have been very few options. For example, Patent Document 1 describes a cleaning resin composition for a low temperature range, and it is described that the cleaning resin composition contains an olefin resin.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] International Publication No. 2007 / 116920 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, conventional cleaning resin compositions for low-temperature ranges often lacked sufficient cleaning performance. Therefore, the present invention aims to provide a cleaning resin composition for cleaning resin compositions that are molded in a relatively low-temperature range, which has good cleaning performance, and a method for cleaning a resin molding machine using the same. [Means for solving the problem]

[0006] In response to the above-mentioned problems, the present inventors diligently investigated and found that a cleaning resin composition containing a thermoplastic resin including an olefin-based resin and an inorganic powder containing calcium carbonate having a predetermined average particle size in a predetermined ratio, and further containing predetermined amounts of a sulfate ester-based surfactant and a hydrogenated petroleum resin, provides excellent cleaning performance.

[0007] The present invention provides the following cleaning resin compositions. [1] A cleaning resin composition comprising a thermoplastic resin containing an olefin resin, an inorganic powder containing calcium carbonate with an average particle size of 0.7 μm or more and 6.0 μm or less as measured by the air permeation method in accordance with JIS M8511:2014, a sulfate ester surfactant, and a hydrogenated petroleum resin, wherein the mass ratio of the thermoplastic resin to the inorganic powder is 50:50 to 10:90, the amount of the sulfate ester surfactant is 0.2% by mass or more and 5.0% by mass or less, and the amount of the hydrogenated petroleum resin is 0.5% by mass or more and 3.0% by mass or less. [2] The cleaning resin composition according to [1], wherein the olefin resin is linear low-density polyethylene. [3] The cleaning resin composition according to [2], wherein the linear low-density polyethylene has a melt mass flow rate of 0.5 g / 10 min or more and 4.0 g / 10 min or less at 190°C and a 2.16 kg load, as measured in accordance with JIS K7210-1:2014. [4] The cleaning resin composition according to any one of [1] to [3], wherein the calcium carbonate is heavy calcium carbonate. [5] The cleaning resin composition according to any one of [1] to [4], wherein the sulfate ester surfactant is an alkyl sulfate. [6] The cleaning resin composition according to any one of [1] to [5], wherein the hydrogenated petroleum resin has a softening point of 80°C or higher and 100°C or lower according to JIS K2207:1996. [7] A cleaning resin composition according to any one of [1] to [6], further comprising a metal soap, wherein the amount of the metal soap is 0.5% by mass or more and 5.0% by mass or less. [8] The cleaning resin composition according to [7], wherein the metal soap is magnesium 12-hydroxystearate.

[0008] The present invention provides a method for cleaning the following resin molding machines. [9] A method for cleaning a resin molding machine, comprising the steps of: cleaning the resin molding machine using a cleaning resin composition described in any of [1] to [8] above; recovering the cleaning resin composition from the resin molding machine and crushing it; and cleaning the resin molding machine again using the crushed cleaning resin composition. [Effects of the Invention]

[0009] The present invention provides a cleaning resin composition for cleaning resin compositions that are molded in a relatively low temperature range, which has good cleaning performance, and a method for cleaning a resin molding machine using the same. [Modes for carrying out the invention]

[0010] One embodiment of the present invention will be described in detail below. However, the present invention is not limited to this embodiment. Furthermore, in this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower limit and upper limit.

[0011] 1. Resin composition for cleaning A cleaning resin composition according to one embodiment of the present invention (hereinafter also referred to as the "cleaning composition") is mainly used to clean resin compositions that are molded in a relatively low temperature range. The cleaning composition comprises a thermoplastic resin containing an olefin resin, an inorganic powder containing calcium carbonate having a specific average particle size, a sulfate ester surfactant, and a hydrogenated petroleum resin. Furthermore, the mass ratio of the thermoplastic resin to the inorganic powder is 50:50 to 10:90, the amount of the sulfate ester surfactant is 0.2% by mass or more and 5.0% by mass or less, and the amount of hydrogenated petroleum resin is 0.5% by mass or more and 3.0% by mass or less. As described above, the cleaning composition provides very good cleaning performance, and it is possible to clean processing machines efficiently in a short time. The reason for this is not clear, but it is presumed to be as follows.

[0012] The cleaning composition of this embodiment contains a relatively large amount of inorganic powder relative to the thermoplastic resin. Therefore, when the cleaning composition is introduced into the processing machine, the inorganic powder easily scrapes off resin and burnt residue adhering to the inside of the machine. At this time, the hydrogenated petroleum resin acts as a coupling agent that physically binds the thermoplastic resin and the inorganic powder. Thus, it is possible to discharge the residual resin and burnt residue scraped off by the inorganic powder together with the thermoplastic resin (cleaning composition). Furthermore, because the cleaning composition contains a sulfate ester-based surfactant, burnt residue is more easily lifted from the surface of the processing machine (metal), which also results in significantly improved cleaning performance.

[0013] Furthermore, the cleaning composition of this embodiment does not need to contain styrene-derived components (e.g., polystyrene), which have been restricted in recent years. Therefore, it can be an environmentally friendly cleaning composition. Moreover, as will be described later, the cleaning composition of this embodiment does not easily deteriorate in performance even after repeated use. Therefore, it can be used multiple times, and has the advantage of being a cleaning composition that is excellent in terms of cost and environmental considerations. The components of the cleaning composition of this embodiment will be described below.

[0014] 1-1.Thermoplastic resin The thermoplastic resin in this embodiment may contain an olefin resin, may contain only an olefin resin, or may contain an olefin resin and other resins. However, it is preferable that the thermoplastic resin contains an olefin resin as its main component. More specifically, it is preferable that the amount of olefin resin in the thermoplastic resin be 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The thermoplastic resin may contain only one type of olefin resin, or may contain two or more types. Furthermore, the olefin resin may be a virgin resin, a recycled resin, or a mixture thereof.

[0015] In this specification, "olefin-based resin" refers to a resin whose main component is olefin-derived structural units. More specifically, it refers to a resin in which the amount of olefin-derived structural units relative to the total structural units of the resin is 50% by mass or more. The olefin-based resin may be a homopolymer of one olefin, a copolymer of two or more olefins, or a copolymer of one or more olefins and one or more other monomers (monomers other than olefins). The amount of olefin-derived structural units in the olefin-based resin is preferably 75% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more.

[0016] Examples of the above olefins include ethylene and α-olefins having 3 to 10 carbon atoms. Specific examples thereof include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 4-methylpentene-1, 3-methyl-1-hexene, and 1-octene, etc. The olefin resin may contain only one kind of constituent unit derived from these, or may contain two or more kinds.

[0017] The above other monomers are not particularly limited as long as they do not impair the object and effect of the present embodiment. Examples of other monomers include diene monomers such as 1,4-hexadiene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, dicyclopentadiene (DCPD), ethylidene norbornene (ENB), norbornadiene, 5-vinyl-2-norbornene; acid (or acid anhydride) modified olefins such as maleic anhydride modified olefin; (meth)acrylates such as methyl (meth)acrylate; etc. The olefin resin may contain only one kind of constituent unit derived from these, or may contain two or more kinds.

[0018] The olefin resin is preferably an "ethylene resin" in which the amount of the constituent unit derived from ethylene is 50% by mass or more based on all the constituent units of the resin. The ethylene resin has a lower melting point compared to other olefin resins. Therefore, when the cleaning resin composition contains an ethylene resin, the fluidity of the cleaning composition in the processing machine tends to be good. Here, examples of the ethylene resin include ethylene homopolymers and copolymers of ethylene and other monomers (ethylene copolymers). Examples of ethylene homopolymers include high-density polyethylene (HDPE): polyethylene having a density of 0.942 g / cm 3 or more, medium-density polyethylene: polyethylene having a density of 0.930 g / cm 3 or more and less than 0.942 g / cm 3 density, low-density polyethylene (LDPE): polyethylene having a density of 0.910 g / cm 3 or more and less than 0.930 g / cm 3Polyethylene having a density less than, linear low density polyethylene (hereinafter, also referred to as "LLDPE"): 0.911 g / cm 3 or more 0.940 g / cm 3 Linear polyethylene having a density less than, and ultra-low density polyethylene (ULDPE): 0.910 g / cm 3 Polyethylene having a density less than is included. On the other hand, the ethylene copolymer may be a binary copolymer of ethylene and another monomer, or may be a terpolymer or higher of ethylene and two or more other monomers. Examples of preferred copolymerization components (other monomers) include vinyl acetate and α-olefins having 3 or more carbon atoms.

[0019] Among ethylene resins, linear low density polyethylene (LLDPE) is particularly preferred. Although linear low density polyethylene (LLDPE) has a low melting point, it has high viscosity even at high temperatures. Therefore, when the cleaning composition contains LLDPE as a thermoplastic resin, it is easier for the cylinder and screw surfaces of the processing machine to rub against the cleaning composition. As a result, the cleaning performance of the cleaning composition is more likely to be further enhanced. Here, the linear low density polyethylene preferably has a melt mass flow rate (hereinafter, also referred to as "MFR") of 0.5 g / 10 min or more and 4.0 g / 10 min or less at 190 °C and a load of 2.16 kg according to JIS K7210-1:2014, and more preferably 1.0 g / 10 min or more and 3.0 g / 10 min or less. When the MFR of linear low density polyethylene (LLDPE) is within this range, the cleaning performance of the cleaning composition is further enhanced.

[0020] Here, as described above, the thermoplastic resin may further contain a resin other than the olefin resin, and the type of the resin other than the olefin resin is not particularly limited. However, with respect to the total amount of the thermoplastic resin, the amount of the styrene resin containing styrene as a constituent unit is preferably 5% by mass or less, and particularly preferably not contained at all from the viewpoint of environmental consideration.

[0021] The amount (total amount) of thermoplastic resin in the resin composition should be in the range where the mass ratio of thermoplastic resin to the inorganic powder described later is 50:50 to 10:90, and more preferably in the range where the mass ratio of thermoplastic resin to the inorganic powder described later is 50:50 to 25:75. More specifically, the amount of thermoplastic resin is preferably 20% to 50% by mass, and more preferably 25% to 45% by mass, relative to the total amount of the resin composition. When the amount of thermoplastic resin is within this range, the fluidity of the cleaning composition tends to fall within an even more favorable range.

[0022] 1-2.Inorganic powder The inorganic powder may be any powder made of an inorganic substance containing calcium carbonate having a predetermined average particle size. The inorganic powder may contain only the calcium carbonate, or it may contain the calcium carbonate and other inorganic substances. However, it is preferable that the inorganic powder contains calcium carbonate as its main component. More specifically, it is preferable that the amount of calcium carbonate in the inorganic powder be 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0023] The average particle size of calcium carbonate, measured by the air permeation method in accordance with JIS M8511:2014, should be between 0.7 μm and 6.0 μm, but is more preferably between 1.0 μm and 4.0 μm. The above average particle size is calculated from the specific surface area measurement results obtained by the air permeation method in accordance with JIS M8511:2014. An example of a specific surface area measuring device is the Shimadzu SS-100 specific surface area measuring device. If the average particle size of calcium carbonate is 0.7 μm or larger, it becomes easier to scrape out residual resin and burnt residue inside the processing machine. On the other hand, if the average particle size of calcium carbonate is 6.0 μm or smaller, the calcium carbonate can easily penetrate into the fine details of the processing machine, making it easier to clean those details. Furthermore, if the average particle size of calcium carbonate is within the above range, it is less likely to cause scratches on the processing machine during cleaning.

[0024] The shape of calcium carbonate is not particularly limited as long as it satisfies the above-mentioned average particle size. It may be particulate, flake, granular, fibrous, or any other form. Furthermore, in the case of particulate matter, it may be spherical, as is generally the case with synthetic methods, or it may be irregularly shaped, as is the case with natural minerals that have been collected and crushed.

[0025] Calcium carbonate may be prepared by a synthetic method, so-called light calcium carbonate. Alternatively, it may be so-called heavy calcium carbonate obtained by mechanically crushing and classifying natural raw materials such as limestone, which are mainly composed of CaCO3. Furthermore, a combination of light calcium carbonate and heavy calcium carbonate may be used. Among these, heavy calcium carbonate is more preferable. Heavy calcium carbonate is often irregular in shape, and such heavy calcium carbonate tends to have good scraping properties for residual resin and burnt residue.

[0026] Here, the calcium carbonate may be surface-modified or not. From the viewpoint of dispersibility and fluidity (suppression of retention) in the processing machine, surface modification is preferable. Examples of surface modification methods for calcium carbonate include physical modification methods such as plasma treatment, and chemical modification methods such as coupling agents and surfactants. Examples of coupling agents that can be used in chemical modification methods include silane coupling agents and titanium coupling agents. As for surfactants, any anionic, cationic, nonionic, or amphoteric surfactant can be used, and examples include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

[0027] On the other hand, examples of inorganic substances other than calcium carbonate include magnesium carbonate, zinc oxide, titanium dioxide, silica, alumina, clay (e.g., talc and kaolin), aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, graphite, etc. These may be synthetic or derived from natural minerals. The inorganic powder may contain only one of these or two or more.

[0028] Furthermore, these shapes are not particularly limited as long as they do not impair the purpose and effect of this embodiment, and may be particulate, flake-shaped, granular, fibrous, etc. In the case of particulate matter, they may be spherical, as is generally the case with synthesis methods, or they may be irregularly shaped, as is the case with pulverized collected natural minerals. These may also be surface-treated. However, it is preferable that the average particle size of these inorganic materials, as measured by the air permeability method in accordance with JIS M8511:2014, be between 0.7 μm and 6.0 μm.

[0029] The amount of inorganic powder in the cleaning composition of this embodiment may be any amount such that the mass ratio of the thermoplastic resin to the inorganic powder is in the range of 50:50 to 10:90. However, the amount of inorganic powder (total amount) is preferably 50% to 80% by mass, and more preferably 55% to 75% by mass, relative to the total amount of the resin composition. When the amount of inorganic powder is within this range, the inorganic substance makes it easier to scrape off residual resin and burnt residue, and the cleaning performance of the cleaning composition tends to improve further.

[0030] 1-3. Sulfate ester surfactants A sulfate ester surfactant can be any surfactant containing a sulfate ester structure. The cleaning composition may contain only one type of sulfate ester surfactant, or it may contain two or more types.

[0031] Examples of sulfate ester surfactants include higher alcohol sulfate salts; alkyl sulfates (also known as alkyl sulfates); polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylaryl sulfates, polyoxyethylene alkylphenyl ether sulfates, sulfate esters of polyoxyethylene alkylphenyl ether polymers, polyoxyethylene benzylphenyl ether sulfates, polyoxyethylene styrylphenyl ether sulfates, sulfate esters of polyoxyethylene styrylphenyl ether polymers, sulfate esters of polyoxyethylene polyoxypropylene block polymers, sulfated olefins, and salts thereof. Examples of the above salts include metal salts (Na, K, Ca, Mg, Zn, etc.), ammonium salts, alkanolamine salts, and aliphatic amine salts.

[0032] Among these, alkyl sulfates are preferred because they do not have a clear melting point and maintain a relatively high viscosity even at high temperatures. The alkyl group in the alkyl sulfate may be linear or branched. The number of carbon atoms in the alkyl group is preferably 8 to 20, and more preferably 10 to 18. Examples of alkyl sulfates include sodium octyl sulfate, sodium lauryl sulfate, sodium hexadecyl sulfate, and sodium stearyl sulfate.

[0033] The amount (total amount) of sulfate ester surfactant in the cleaning composition of this embodiment may be 0.2% by mass or more and 5.0% by mass or less, and preferably 0.5% by mass or more and 3.0% by mass or less. When the amount of sulfate ester surfactant is within this range, as described above, the burn marks tend to lift off the surface of the processing machine (metal). In addition, the fluidity of the cleaning composition is also improved. Furthermore, the antistatic effect of the sulfate ester surfactant can suppress the adsorption of dust and other particles during the manufacturing and storage of the cleaning composition.

[0034] 1-4. Hydrogenated petroleum resins In this specification, "hydrogenated petroleum resin" refers to a resin obtained by further hydrogenating a copolymer (petroleum resin) of the liquid fraction (including diolefins, olefins, aromatic olefins, paraffins, etc.) remaining after separating gaseous olefins from fractions obtained by the decomposition or reforming of petroleum. Therefore, the types and amounts of monomer components in hydrogenated petroleum resins vary widely, and it is not possible to specify their composition in general, but they all share the common feature of containing C5-C9 aliphatic rings. These hydrogenated petroleum resins have high affinity for olefin-based resins and inorganic powders in the thermoplastic resins mentioned above.

[0035] The hydrogenated petroleum resin may be a commercially available product. Examples of commercially available hydrogenated petroleum resins include the Alcon series from Arakawa Chemical Industries, Ltd., the T-REZ series from ENEOS Corporation, the Easttac series from Eastman Chemical Corporation, and the iMarb series from Idemitsu Corporation.

[0036] The softening point of the hydrogenated petroleum resin is preferably between 80°C and 135°C, and more preferably between 80°C and less than 95°C. When the softening point of the hydrogenated petroleum resin is within this range, it becomes easier to bind the thermoplastic resin and inorganic powder mentioned above.

[0037] The amount of hydrogenated petroleum resin in the cleaning composition of this embodiment may be 0.5% by mass or more and 3.0% by mass or less, and preferably 1.0% by mass or more and 2.5% by mass or less. When the amount of hydrogenated petroleum resin is 0.5% by mass or more, the thermoplastic resin and inorganic powder are sufficiently bound together, and residual resin and burnt residue scraped off by the inorganic powder are further easily discharged together with the cleaning composition. On the other hand, when the amount of hydrogenated petroleum resin is 3.0% by mass or less, the dischargeability of the cleaning composition from the processing machine tends to be even better.

[0038] 1-5. Metallic soaps As described above, the cleaning composition may further contain metal soaps as needed. When the cleaning composition contains metal soaps, the dispersibility of the inorganic powder in the cleaning composition tends to improve further. As a result, the cleaning performance of the cleaning composition tends to improve further.

[0039] In this specification, "metal soap" refers to a salt of a long-chain fatty acid and a metal. The long-chain fatty acid may be a saturated fatty acid, an unsaturated fatty acid, or an aliphatic dicarboxylic acid. From the viewpoint of enhancing the cleaning effect of the cleaning composition, saturated fatty acids with 12 to 30 carbon atoms or unsaturated fatty acids with 12 to 30 carbon atoms are preferred, and saturated fatty acids with 12 to 30 carbon atoms are more preferred. Examples of metals include zinc, calcium, magnesium, aluminum, barium, lithium, sodium, potassium, and manganese.

[0040] Specific examples of metallic soaps include lithium salts such as lithium stearate, lithium 12-hydroxystearate, lithium laurate, lithium oleate, lithium 2-ethylhexanoate, lithium behenate, and lithium montanate; sodium salts such as sodium stearate, sodium 12-hydroxystearate, sodium laurate, sodium oleate, sodium 2-ethylhexanoate, sodium behenate, and sodium montanate; potassium salts such as potassium stearate, potassium 12-hydroxystearate, potassium laurate, potassium oleate, potassium 2-ethylhexanoate, potassium behenate, and potassium montanate; and magnesium stearate, magnesium 12-hydroxystearate, magnesium laurate, magnesium oleate, magnesium 2-ethylhexanoate, magnesium behenate, and montanate. This includes magnesium salts such as magnesium stearate; calcium salts such as calcium stearate, calcium 12-hydroxystearate, calcium laurate, calcium oleate, calcium 2-ethylhexanoate, calcium behenate, and calcium montanaate; barium salts such as barium stearate, barium 12-hydroxystearate, barium laurate, barium behenate, and barium montanaate; zinc salts such as zinc stearate, zinc 12-hydroxystearate, zinc laurate, zinc oleate, zinc 2-ethylhexanoate, zinc behenate, and zinc montanaate; lead salts such as lead stearate, lead 12-hydroxystearate, lead behenate, and lead montanaate; aluminum salts such as aluminum stearate, aluminum behenate, and aluminum montanaate; manganese oleate; barium ricinoleate; cobalt stearate; and others.

[0041] Among these, magnesium 12-hydroxystearate is preferred because it has a particularly high affinity for the above-mentioned sulfate ester-based surfactants and is easy to improve the dispersibility of inorganic powders.

[0042] The amount of metal soap in the cleaning composition of this embodiment is preferably 0.5% by mass or more and 5.0% by mass or less, and more preferably 1.0% by mass or more and 3.0% by mass or less. When the amount of metal soap is within this range, the dispersibility of the inorganic powder tends to be even better. The content ratio (by mass) of the sulfate ester surfactant and the metal soap is preferably 6:4 to 4:6, and more preferably 5:4 to 4:5. When the content ratio of the sulfate ester surfactant and the metal soap is within this range, the cleaning effect of the cleaning composition tends to be even better.

[0043] 1-6. Other ingredients The cleaning composition may further contain components other than those mentioned above, to the extent that it does not impair the purpose and effect of this embodiment. Examples of components other than those mentioned above include hygroscopic agents, antioxidants, flame retardants, and the like.

[0044] The desiccant is not particularly limited as long as it can suppress moisture absorption of the cleaning composition and does not easily affect the components of the cleaning composition. Examples of desiccant include metal oxides such as calcium oxide, magnesium oxide, strontium oxide, and barium oxide, as well as zeolites, silica gel, and activated carbon. When the cleaning composition contains these desiccant, moisture absorption and deterioration of the cleaning composition during storage can be suppressed. The amount of desiccant is appropriately selected depending on the type of desiccant, but is generally preferably 0.1% to 3% by mass of the total mass of the cleaning composition.

[0045] On the other hand, the antioxidant can be any component capable of suppressing the deterioration of the cleaning composition by oxygen. Examples include phosphorus-based antioxidants, phenol-based antioxidants, and pentaerythritol-based antioxidants. The resin composition may contain one of these individually or two or more. The amount can also be selected as appropriate. Among the above, phosphorus-based antioxidant stabilizers, more specifically phosphorus-based phosphate esters and phosphoric acid esters, are preferred. Examples of phosphorus-based phosphate esters include, for example, triphenyl phosphite, trisnonylphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, and other triesters, diesters, monoesters, etc. of phosphorus-based phosphates.

[0046] Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(nonylphenyl) phosphate, and 2-ethylphenyldiphenyl phosphate.

[0047] Examples of phenolic antioxidants include α-tocopherol, butylhydroxytoluene, cinapyl alcohol, vitamin E, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-t-butyl-6-(3'-t-butyl-5'-methyl-2'-hydroxybenzyl)-4-methylphenyl acrylate, 2,6-di-t-butyl-4-(N,N-dimethylaminomethyl)phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, and tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane.

[0048] The flame retardant is not particularly limited, but for example, halogenated flame retardants or non-phosphorus halogenated flame retardants such as phosphorus-based flame retardants or metal hydrates can be used. The resin composition may contain one of these alone or two or more. The amount of flame retardant is selected as appropriate.

[0049] Examples of halogenated flame retardants include halogenated bisphenol compounds such as halogenated bisphenylalkanes, halogenated bisphenyl ethers, halogenated bisphenyl thioethers, and halogenated bisphenylsulfones, as well as bisphenol-bis(alkyl ether) compounds such as brominated bisphenol A, brominated bisphenol S, chlorinated bisphenol A, and chlorinated bisphenol S. Examples of phosphorus-based flame retardants include aluminum tris(diethylphosphinate), bisphenol A bis(diphenyl phosphate), triarylisopropyl phosphate, cresyl di2,6-xylenyl phosphate, and aromatic condensed phosphate esters. Examples of metal hydrates include aluminum trihydrate, magnesium dihydrate, or combinations thereof.

[0050] Furthermore, the above-mentioned flame retardants may be combined with flame retardant additives. Examples of flame retardant additives include antimony oxides such as antimony trioxide and antimony pentoxide, zinc oxide, iron oxide, aluminum oxide, molybdenum oxide, titanium oxide, calcium oxide, and magnesium oxide.

[0051] 1-7. Shape and physical properties of resin compositions The shape of the cleaning composition in this embodiment is not particularly limited and can be any shape, such as particulate, pelletized, or lumpy. If the cleaning composition is pelletized, the shape of the pellet is not particularly limited and can be cylindrical, spherical, ellipsoidal, or any other shape. The size is also not particularly limited and can be appropriately selected according to the shape. For example, in the case of spherical pellets, the diameter may be 1 to 10 mm. In the case of ellipsoidal pellets, the major axis may be about 1 to 10 mm and the aspect ratio may be about 0.1 to 1.0. In the case of cylindrical pellets, the diameter may be about 1 to 10 mm and the height may be about 1 to 10 mm.

[0052] Furthermore, the MFR of the cleaning composition of this embodiment, measured in accordance with JIS K7210-1:2014 at 190°C and a 2.16 kg load, is preferably 0.1 g / 10 min to 3.0 g / 10 min, and more preferably 0.5 g / 10 min to 2.5 g / 10 min. When the MFR of the cleaning composition is within this range, the fluidity within the processing machine and the discharge from the processing machine tend to be further improved.

[0053] 1-8. Method for producing a cleaning composition The method for producing the above-mentioned cleaning composition is not particularly limited. Any method that allows for the uniform mixing of thermoplastic resin, inorganic powder, sulfate ester surfactant, hydrogenated petroleum resin, and optionally metal soap and other components is acceptable. These may be mixed simultaneously, or some may be mixed first and the rest later. Examples of mixing methods include melt kneading. The apparatus for performing melt kneading is not particularly limited, and general extruders, kneaders, Banbury mixers, etc., can be used. In particular, from the viewpoint of obtaining a cleaning composition with a uniform composition, kneading with a twin-screw kneader is preferable.

[0054] 2. Method for cleaning a processing machine using a cleaning composition The above-described cleaning composition can be used to clean resin molding machines (processing machines). The type of processing machine is not particularly limited and examples include injection molding machines, inflation molding machines, blow molding machines, extrusion molding machines, etc. Furthermore, the cleaning resin composition can be used to clean the resin flow paths such as cylinders, screws, and molds of these machines.

[0055] Furthermore, the above-mentioned cleaning composition is used when changing the resin composition used in the processing machine or when periodically cleaning the inside of the processing machine. The resin composition to be cleaned is preferably a composition that is molded at a relatively low temperature, as described above. For example, it is preferably a composition that is molded at a temperature of approximately 120°C to 250°C, and more preferably a composition that is molded at a temperature of 130°C to 230°C. Examples of such resin compositions include resin compositions containing olefin resins.

[0056] When cleaning a processing machine using the above-mentioned cleaning composition, the following procedure can be followed. However, the cleaning method is not limited to this method.

[0057] The cleaning composition is supplied to the desired processing machine. The processing machine is then operated so that the cleaning composition flows through its interior. After that, the cleaning composition is discharged from the processing machine. At this time, the temperature of the processing machine is preferably the same as the processing temperature of the material to be cleaned, for example, preferably between 120°C and 250°C.

[0058] The amount of cleaning composition supplied to the processing machine and the cleaning time are appropriately selected according to the type of processing machine and the purpose of cleaning the machine. For example, when cleaning a processing machine for resin replacement (changing the type of resin composition used), it is preferable to continue supplying and discharging the cleaning composition until the previously used resin composition and burnt residue are no longer discharged along with the cleaning composition. In this case, the timing of the end of cleaning may be determined by the color and properties of the discharged cleaning composition. Alternatively, the timing may be determined by disassembling a part of the processing machine and checking whether residual resin or burnt residue is adhering to the inside. On the other hand, for periodic cleaning of the processing machine or cleaning before using the processing machine, cleaning may be completed by supplying and discharging a predetermined amount or a predetermined time of cleaning composition.

[0059] In this embodiment, after performing the cleaning step of the processing machine according to the procedure described above, the cleaning composition discharged from the processing machine may be recovered, crushed, and then the processing machine may be cleaned again using the resin composition. In other words, the used cleaning composition used to clean a particular processing machine may be reused to clean another or the same processing machine. As will be specifically shown in the examples described later, the cleaning resin assembly of this embodiment can maintain about 70% of its initial cleaning power even after being used four times (recycled three times). Therefore, the cleaning method using the cleaning composition of this embodiment can reduce the cost of cleaning and is also excellent from the standpoint of being environmentally friendly. [Examples]

[0060] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0061] 1. Preparation of materials The following materials were used in the following examples and comparative examples.

[0062] (thermoplastic resin) LLDPE: Linear low-density polyethylene (measured according to JIS K7210-1:2014, MFR: 3.0 g / 10 min at 190°C and 2.16 kg load, melting point 123°C) PP: Polypropylene (Measured according to JIS K7210-1:2014, MFR: 2.4g / 10min at 230℃, 2.16kg load, melting point 160℃)

[0063] (Inorganic powder) • Heavy calcium carbonate powder (manufactured by Takehara Chemical Co., Ltd., Sunlight SL-1500, average particle size 2.0 μm) The average particle size was calculated from the specific surface area measurement results using the SS-100 specific surface area measuring device manufactured by Shimadzu Corporation, in accordance with the air permeability method compliant with JIS M8511:2014.

[0064] (Surfactants) • TB-160: Alkyl sulfate (manufactured by Matsumoto Oil & Fat Co., Ltd.) • Alkyl ether sulfate • Sulfonic acid type surfactant

[0065] (Hydrogenated petroleum resin) Alcon P-90 (manufactured by Arakawa Chemical Co., Ltd., softening point 90±5℃) Alcon P-115 (manufactured by Arakawa Chemical Co., Ltd., softening point 115±5℃)

[0066] (Metallic soap) MS6:12-Magnesium hydroxystearate (manufactured by Nitto Chemical Industries, Ltd.) (For comparison, commercially available product) Asaclin UP (manufactured by Asahi Kasei Corporation)

[0067] 2. Preparation of the cleaning composition Thermoplastic resin, inorganic powder, surfactant, hydrogenated petroleum resin, and metal soap were fed into a Parker HK-25D co-rotating twin-screw compounding extruder (φ25mm, L / D=41) in the mass ratios shown in Tables 1 and 2. The mixture was then melt-kneaded at a cylinder temperature of 230°C and extruded into strands. After the extruded resin composition was cooled, it was cut to obtain pellets of the cleaning composition. In Comparative Example 7, (virgin) polypropylene was used as the cleaning composition, and in Comparative Example 8, Asaclin UP (manufactured by Asahi Kasei Corporation) was used as the cleaning composition.

[0068] 3. Evaluation The cleaning performance of the cleaning compositions obtained above for residues inside the processing machine was evaluated using the following methods. The results are shown in Tables 1 and 2.

[0069] (1) Cleaning performance evaluation 1 A standard PP plate was produced by introducing 1 kg of polypropylene (MFR (230°C, 2.16 kg load): 0.5 g / 10 min) into a laboplast mill (small extruder) and performing extrusion molding at 200°C. Subsequently, 1 kg of a resin composition (to be washed) containing 95% by mass of polypropylene (MFR (230°C, 2.16 kg load): 0.5 g / 10 min) and 5% by mass of red pigment was supplied to the laboplast mill, and extrusion molding was performed similarly at 200°C. Next, 1 kg each of the cleaning compositions prepared in the examples and comparative examples were supplied to a laboplast mill, and these were extruded at 200°C to perform cleaning. Again, 0.5 kg of polypropylene (MFR (230°C, 2.16 kg load): 0.5 g / 10 min) was introduced into the above-mentioned lab plast mill, and extrusion molding was performed at 200°C. After washing, a PP plate was produced. The color difference ΔE between the standard PP plate and the washed PP plate was measured using a spectrophotometer to evaluate the cleaning performance of the cleaning composition. A smaller color difference ΔE indicates higher cleaning performance. The results are shown in Tables 1 and 2.

[0070] (2) Cleaning performance evaluation 2 A standard PP plate was produced by introducing 1 kg of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min) into a 30t injection molding machine and performing injection molding at 200°C. Subsequently, 1 kg of a resin composition (to be cleaned) containing 95% by mass of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min) and 5% by mass of red pigment was supplied to the 30t injection molding machine, and injection molding was performed in the same manner at 200°C. Next, 0.3 kg each of the cleaning compositions prepared in the examples and comparative examples were supplied to a 30t injection molding machine, and these were injected at 200°C to perform cleaning. Again, 0.5 kg of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min) was introduced into the 30t injection molding machine, injection molding was performed at 200°C, and after cleaning, a PP plate was produced. The color difference ΔE between the standard PP plate and the washed PP plate was measured using a spectrophotometer to evaluate the cleaning performance of the cleaning composition. A smaller color difference ΔE indicates higher cleaning performance. The results are shown in Tables 1 and 2.

[0071] (3) Burn removal properties A 1 kg resin composition containing 99% by mass of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min), 0.5% by mass of malic acid, and 0.5% by mass of alkanolamide) was supplied to a 30t injection molding machine, and injection molding was performed at 200°C. This forced burning of the resin. Next, 0.3 kg each of the cleaning compositions prepared in the examples and comparative examples were supplied to a 30t injection molding machine, and cleaning was performed by injecting these compositions. Subsequently, 0.2 kg of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min) was introduced into the 30t injection molding machine, and after cleaning, a PP plate was produced. After cleaning, the PP plate was observed, and the amount of burn marks contained within the PP plate was visually inspected. Furthermore, the injection molding machine was disassembled, the screw portion was wiped with a cloth, and the presence or absence of burn marks was observed. In addition, the presence or absence of burn marks adhering to the nozzle was checked under a microscope. The results are shown in Tables 1 and 2.

[0072] (4) Dischargeability 1 kg of polyethylene (MFR (190°C, 2.16 kg load): 3.0 g / 10 min) was introduced into a 30t injection molding machine, and injection molding was performed at 200°C. Subsequently, 1 kg each of the cleaning compositions prepared in the examples and comparative examples were supplied to a 30-ton injection molding machine, and these were injected to perform cleaning. Subsequently, 2 kg of polyethylene (MFR (190°C, 2.16 kg load): 3.0 g / 10 min) was introduced, and extrusion molding was performed at 200°C. After washing, a PE plate was produced. The PE plate was then observed, and the number of fish-eyes was measured. Fish-eyes are caused by the gelation of the cleaning composition remaining in the molding machine. A lower number of fish-eyes indicates better discharge of the cleaning composition from the processing machine. The results are shown in Tables 1 and 2.

[0073] 4.Results [Table 1]

[0074] [Table 2]

[0075] As shown in Table 1, in Examples 1 to 9, where the mass ratio of LLDPE to calcium carbonate was 50:50 to 10:90, the amount of sulfate ester surfactant was 0.2% to 5.0% by mass, and the amount of hydrogenated petroleum resin was 0.5% to 3.0% by mass, the cleaning performance evaluation was better than that of a commercially available cleaning composition (Comparative Example 8). Furthermore, the cleaning compositions of Examples 1 to 9 made it easy to discharge any burn marks that occurred on the processing machine, and the dischargeability of the cleaning composition itself was also excellent.

[0076] In contrast, when the amount of calcium carbonate was insufficient, or when the amount of sulfate ester-based surfactant or hydrogenated petroleum resin did not meet the above requirements, the cleaning performance deteriorated in all cases (Comparative Examples 1-7).

[0077] 5.Reusability The reusability of the cleaning compositions in the examples was evaluated using the following method.

[0078] (1) Test method (0th recycling attempt) One kilogram of a resin composition containing 95% by mass of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min) and 5% by mass of red pigment was supplied to a 30t injection molding machine and extruded at 200°C. Next, the cleaning composition prepared in Example 1 was supplied to a 30t injection molding machine and injection molding was performed. The amount of cleaning composition discharged that was equivalent in color to the original cleaning composition was then determined. After that, the cleaning composition used for cleaning was recovered and crushed.

[0079] (First recycling attempt) One kilogram of a resin composition containing 95% by mass of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min) and 5% by mass of red pigment was supplied to a 30t injection molding machine and extruded at 200°C. Next, the cleaning composition recovered and pulverized above was supplied to a 30t injection molding machine and injection molding was performed. The amount of cleaning composition discharged that was equivalent in color to the color before supply was then determined. After that, the cleaning composition used for cleaning was recovered and pulverized.

[0080] (Second recycling attempt) One kilogram of a resin composition containing 95% by mass of polypropylene (MFR (230°C, 2.16 kg load): 21 g / 10 min) and 5% by mass of red pigment was supplied to a 30t injection molding machine and extruded at 200°C. Next, the cleaning composition recovered and pulverized above was supplied to a 30t injection molding machine and injection molding was performed. The amount of cleaning composition discharged that was equivalent in color to the color before supply was then determined. After that, the cleaning composition used for cleaning was recovered and pulverized.

[0081] (3rd recycling) One kilogram of a resin composition containing 95% by mass of polypropylene (MFR (230°C, 2.16) kg load): 21 g / 10 min) and 5% by mass of red pigment was supplied to a 30t injection molding machine and extruded at 200°C. Next, the cleaning composition recovered and crushed above was supplied to a 30-ton injection molding machine and injection molding was performed. The amount of cleaning composition discharged that was equivalent in color to the color before supply was then determined.

[0082] (2) Evaluation results The amount of cleaning composition and the time required for each cleaning process are shown in Table 3 below.

[0083] [Table 3]

[0084] As shown in Table 3 above, although the efficiency decreases with repeated recycling, the cleaning efficiency remained at approximately 70% of the initial level even after three recycling cycles. Therefore, the above cleaning composition can be considered reusable. [Industrial applicability]

[0085] The cleaning resin composition of the present invention makes it possible to efficiently clean the inside of a processing machine in a short amount of time. Furthermore, the cleaning resin composition can be used repeatedly. This cleaning resin composition is extremely useful in the field of manufacturing various industrial products.

Claims

1. Thermoplastic resins containing olefin resins, An inorganic powder containing calcium carbonate, with an average particle size of 0.7 μm or more and 6.0 μm or less, as measured by the air permeation method in accordance with JIS M8511:2014, Sulfate ester surfactants and Hydrogenated petroleum resin and A cleaning resin composition containing, The mass ratio of the thermoplastic resin to the inorganic powder is 50:50 to 10:

90. The amount of the aforementioned sulfate ester surfactant is 0.2% by mass or more and 5.0% by mass or less. The amount of the hydrogenated petroleum resin is 0.5% by mass or more and 3.0% by mass or less. A resin composition for cleaning.

2. The olefin resin is linear low-density polyethylene. The cleaning resin composition according to claim 1.

3. The linear low-density polyethylene has a melt mass flow rate of 0.5 g / 10 min or more and 4.0 g / 10 min or less at 190°C and a 2.16 kg load, as measured in accordance with JIS K7210-1:2014. The cleaning resin composition according to claim 2.

4. The calcium carbonate is heavy calcium carbonate. The cleaning resin composition according to claim 1.

5. The aforementioned sulfate ester surfactant is an alkyl sulfate. The cleaning resin composition according to claim 1.

6. The softening point of the aforementioned hydrogenated petroleum resin, according to JIS K2207:1996, is 80°C or higher and 100°C or lower. The cleaning resin composition according to claim 1.

7. It further contains metallic soaps, The amount of the aforementioned metal soap is 0.5% by mass or more and 5.0% by mass or less. The cleaning resin composition according to claim 1.

8. The aforementioned metal soap is magnesium 12-hydroxystearate. The cleaning resin composition according to claim 7.

9. A step of cleaning a resin molding machine using the cleaning resin composition described in any one of claims 1 to 8, The process of recovering the cleaning resin composition from the resin molding machine and crushing it, A step of newly cleaning the resin molding machine using the cleaning resin composition after pulverization, including, A method for cleaning a resin molding machine.

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