Method for producing blow-molded article, resin composition, and pellet

Abstract

A method for producing a blow-molded article, said method being capable of preventing the transfer of a wax-derived component to the surface of a blow-molded article. The method for producing a blow-molded article includes a step in which a blow-molded article is obtained via blow molding using a resin mixture containing at least wax, polyethylene or polypropylene and a carbodiimide compound.

Description

Method for producing blow-molded article, resin composition, and pellets

[0001] The present disclosure relates to a method for producing a blow-molded article, a resin composition, and pellets.

[0002] In electrophotographic image forming devices, toner bottles that supply toner and the like must be strong enough to withstand being dropped, so blow-molded products made of polyethylene (hereinafter sometimes referred to as "PE") or polypropylene (hereinafter sometimes referred to as "PP") are sometimes used in addition to polyethylene terephthalate, a polyester resin (Patent Document 1).

[0003] In recent years, from the viewpoint of environmental protection, thermoplastic resin products and their parts have been collected, and then recycled by temporarily changing their original shape. Here, as a method for recycling thermoplastic resins such as polyethylene or polypropylene, chemical recycling and material recycling are known, as described in paragraph

[0002] of Patent Document 2.

[0004] Japanese Patent Laid-Open No. 06-067536 Japanese Patent Laid-Open No. 2009-001693

[0005] Chemical recycling, as disclosed in Patent Document 2, requires multiple steps, including the need for decomposition and polymerization equipment, resulting in high recycling costs. It also places a heavy burden on the environment. Meanwhile, in material recycling, a bottle washing process is generally performed. However, bottle washing may be performed multiple times using water, acid, alkali, etc., and a drying process is also required. Therefore, bottle washing can also increase the environmental burden.

[0006] Therefore, from the perspective of reducing the environmental impact, the present inventors simplified or omitted the cleaning of toner bottles to be recycled, and instead produced new toner bottles using polyethylene or polypropylene (hereinafter also referred to as "material recycled PE" or "MR-PE" or "material recycled PP" or "MR-PP") obtained from toner bottles with toner still attached to the inside. Then, when toner was placed in the toner bottle obtained in this manner, it was found that the surfaces of the toner particles sometimes deformed at the points of contact between the toner in the toner bottle and the inner surface of the toner bottle. Toner particles with deformed surfaces can lead to development defects, such as insufficient transfer during electrophotographic development (when the toner is transferred to the photosensitive drum), and as a result, can cause density unevenness in electrophotographic images.

[0007] At least one aspect of the present disclosure is directed to providing a method for producing a blow-molded article that can prevent migration of wax-derived components to the surface of the blow-molded article. At least one aspect of the present disclosure is directed to providing a resin composition that contributes to preventing migration of wax-derived components to the surface of the blow-molded article. At least one aspect of the present disclosure is directed to providing pellets that contribute to preventing migration of wax-derived components to the surface of the blow-molded article.

[0008] According to at least one aspect of the present disclosure, there is provided a method for producing a blow-molded article, the method comprising: blow-molding a resin mixture containing at least a wax, polyethylene or polypropylene, and a carbodiimide compound to obtain a blow-molded article. According to at least one aspect of the present disclosure, there is provided a resin composition containing a melt-kneaded mixture of wax, polyethylene or polypropylene, and a carbodiimide compound. According to at least one aspect of the present disclosure, there is provided a pellet containing a melt-kneaded mixture of wax, polyethylene or polypropylene, and a carbodiimide compound.

[0009] According to at least one aspect of the present disclosure, a method for producing a blow-molded article that can prevent migration of wax-derived components to the surface of the blow-molded article can be obtained. According to at least one aspect of the present disclosure, a resin composition that contributes to preventing migration of wax-derived components to the surface of the blow-molded article can be obtained. Furthermore, according to at least one aspect of the present disclosure, pellets that contribute to preventing migration of wax-derived components to the surface of the blow-molded article can be obtained.

[0010] FIG. 1 is a schematic diagram of an image forming apparatus; FIG. 2 is a schematic diagram showing a preform molding method; FIG. 3 is a schematic diagram showing a stretch blow molding method; FIG. 4 is a schematic diagram of one-stage stretch blow molding; FIG. 5 is a schematic diagram of direct blow molding; FIG. 6 is a schematic diagram of a biaxially stretched blow bottle; and FIG. 7 is a schematic diagram of a direct blow bottle. FIG. 8 is a presumed reaction scheme between a wax-derived component and a carbodiimide compound.

[0011] In the present disclosure, the expressions "XX or more and YY or less" and "XX to YY" representing a numerical range mean a numerical range including the endpoints, that is, the lower and upper limits, unless otherwise specified. When a numerical range is described in stages, any combination of the upper and lower limits of each numerical range is also disclosed. Furthermore, in the present disclosure, for example, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0012] As mentioned above, when toner is stored in a toner bottle molded using MR-PE or MR-PP obtained from a toner bottle with toner still attached, deformation of the surface of the stored toner sometimes occurs. The inventors speculate that the reason for this is as follows.

[0013] That is, it is believed that the toner bottle contains wax contained in the toner that adhered to the toner bottle before recycling. It is believed that at least a portion of the wax is present on the inside surface (hereinafter also referred to as the "inner surface") of the toner bottle formed using MR-PE or MR-PP. It is also believed that at least a portion of the wax contained in the MR-PE or MR-PP is hydrolyzed by moisture in the air, etc., and that the hydrolyzate is present on the inner surface of the toner bottle after blow molding. It is also believed that when a preform containing MR-PE or MR-PP is used as the resin mixture, at least a portion of the preform is hydrolyzed by moisture in the air, etc., and that the hydrolyzate is present on the inner surface of the toner bottle after blow molding.

[0014] It is believed that the toner particles' surfaces are deformed when the toner contained in the toner bottle comes into contact with the wax and hydrolysates exposed on the inner surface of the toner bottle. Hereinafter, wax and its hydrolysates are collectively referred to as "wax-derived components." In addition, in this disclosure, the deformation of the toner particle surfaces caused by wax-derived components may be referred to as "chemical attack."

[0015] It is believed that migration of wax-derived components to the inner surface of a toner bottle is likely to occur during heating during blow molding. During blow molding, the raw materials for a blow-molded product are heated to or above the glass transition temperature of the primary material, polyethylene or polypropylene. Polyethylene or polypropylene exhibits high molecular mobility above its glass transition temperature. On the other hand, wax generally has a low molecular weight, for example, of approximately 300 to 500, and wax hydrolysates have even lower molecular weights. Therefore, wax-derived components are likely to migrate to the surface, including the inner surface, of a blow-molded product. Therefore, when a resin mixture is heated to or above the melting point of the primary material, polyethylene or polypropylene, and then blow-molded, the wax-derived components are likely to migrate to the surface, including the inner surface, of the blow-molded product. Therefore, a greater amount of wax-derived components is present on the inner surface of a toner bottle blow-molded from MR-PE or MR-PP.

[0016] Furthermore, when a preform is used for blow molding, there is almost no difference in the concentration of wax-derived components between the interior and the inner surface of the preform immediately after molding. However, when the preform is stretch-blow molded and heated to a temperature above the melting point of the polyethylene or polypropylene that is the main material of the preform, it is thought that the wax-derived components with low molecular weights migrate to the surface, including the inner surface, of the preform. Therefore, a larger amount of wax-derived components is present on the inner surface of a toner bottle that is a stretch-blow molded product of a preform containing MR-PE or MR-PP.

[0017] Based on these considerations, the present inventors conducted extensive research to obtain a blow-molded article that can be used as a toner bottle, which can prevent the migration of wax-derived components to the surface of the blow-molded article and prevent deformation of the toner contained therein, on the premise that MR-PE or MR-PP recycled from toner bottles with toner adhering thereto is used. As a result, they found that a blow-molded article obtained by a method of blow-molding a resin mixture containing at least wax, polyethylene or polypropylene, and a carbodiimide compound can contribute to solving the above-mentioned problems.

[0018] The inventors speculate that the reason why blow-molded articles obtained from the above-mentioned resin mixtures contribute to solving the above-mentioned problems is as follows. First, the resin mixture is melt-kneaded during blow molding. During this melt-kneading process, wax-derived components contained in the resin mixture react with the carbodiimide compound, resulting in polymerization of the wax-derived components. It is believed that the polymerized wax-derived components then have reduced fluidity. As a result, it is believed that migration of the wax-derived components to the surface of the preform or blow-molded article is suppressed.

[0019] Another reason is that when the wax contains an ester wax, the wax in the raw material is hydrolyzed by moisture in the air, etc., as described above, and a carboxylic acid is generated as one of the wax-derived components, as shown in Fig. 8A. The generated carboxylic acid then migrates to the inner surface of the preform or toner bottle, which may result in deformation of the toner.

[0020] However, when a resin mixture contains a carbodiimide compound, during the melt-kneading process of the resin mixture, as shown in Figure 8B, carboxylic acid as a wax-derived component reacts with the carbodiimide compound, causing the wax-derived component to relatively polymerize. As a result, it is believed that migration of the wax-derived component is suppressed, and the presence of the wax-derived component on the inner surface of the preform or blow-molded product can be suppressed. Note that Rw1, Rw2, R1, R2, etc. in Figures 8A and 8B represent organic groups in the ester wax or carbodiimide compound.

[0021] A method for producing a blow-molded article according to one embodiment of the present disclosure includes a step of blow-molding a resin mixture containing at least wax, polyethylene or polypropylene, and a carbodiimide compound to obtain a blow-molded article. More specifically, the method includes a step of blow-molding a melt-kneaded resin mixture containing at least wax, polyethylene or polypropylene, and a carbodiimide compound to obtain a blow-molded article.

[0022] Here, "melt-kneading" means applying a shear force to a resin mixture that has been heated to a fluid state, specifically, for example, a resin mixture that has been heated to a temperature equal to or higher than the glass transition temperature, particularly equal to or higher than the melting point, of the polyethylene or polypropylene in the resin mixture. Methods of applying a shear force to a melt-kneaded resin mixture include, for example, a method of applying a shear force to the resin mixture with the screws of a twin-screw extruder while heating the resin mixture, a method of injection-molding a melt of the resin mixture, and a method of extrusion-molding a melt of the resin mixture.

[0023] More specifically, "melt-kneading" includes, for example, heating the resin mixture to a temperature equal to or higher than the glass transition temperature of the polyethylene or polypropylene, more preferably equal to or higher than the melting point of the polyethylene or polypropylene, so that the polyethylene or polypropylene has fluidity and at least a portion of the wax-derived component is melted, or at least a portion of the carbodiimide compound is melted, or at least a portion of the wax-derived component and at least a portion of the carbodiimide compound are melted. The term "melt-kneaded product" includes a product obtained by cooling after the above-mentioned "melt-kneading" step.

[0024] The blow molding method is not particularly limited, and stretch blow molding, direct blow molding, etc. can be employed. That is, the blow molded product may be a stretch blow molded product or a direct blow molded product.

[0025] Stretch blow molding is a method in which a preform as a resin mixture is molded from molten raw materials, and then the preform is stretch-blow molded. On the other hand, direct blow molding is a method in which the molten resin mixture is directly blow-molded. In this case, pellets formed by melt-kneading the raw materials may be used as the resin mixture. Therefore, specific examples of melt-kneading include melt-kneading when producing pellets of a resin mixture, melt-kneading when producing a preform for stretch-blow molding, and melt-kneading by extrusion using an injection molding machine or the like in direct blow molding.

[0026] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments. In the following description, "%" means "% by mass" unless otherwise specified.

[0027] (Pellets, Preforms) Blow-molded articles can be produced by blow-molding pellets or preforms as a resin mixture. That is, pellets and preforms formed by melt-kneading raw materials can be used as the resin mixture. The pellets may also be a pellet mixture obtained by mixing different pellets (pellet blend).

[0028] The pellets contain at least wax, polyethylene or polypropylene, and a carbodiimide compound. The pellets preferably contain a toner containing wax. Details of the method for forming the pellets will be described later. The preform is manufactured from a melt-kneaded resin mixture containing at least wax, polyethylene or polypropylene, and a carbodiimide compound. The preform preferably contains a toner containing wax. The preform can be molded by, for example, injection molding. Details of the method for molding the preform will be described later.

[0029] The polyethylene or polypropylene is not particularly limited as long as it is a thermoplastic polyethylene or polypropylene. The carbodiimide compound has at least one carbodiimide group represented by "-N=C=N-" in the molecule. Examples of the carbodiimide compound include carbodiimide and polycarbodiimide.

[0030] The polyethylene or polypropylene may be recycled polyethylene or polypropylene, or may be virgin polyethylene or polypropylene that has not undergone molecular weight reduction. However, the effects of the present disclosure are more pronounced when the polyethylene or polypropylene is MR-PE or MR-PP obtained by recycling toner bottles. Therefore, it is preferable that the resin mixture contains MR-PE or MR-PP. The MR-PE or MR-PP may be obtained using recycled raw materials with toner adhered to the surface. The toner contains components such as wax. In other words, the MR-PE or MR-PP may contain wax.

[0031] <Polyethylene (PE)> Polyethylene (PE) is obtained by the polymerization reaction of ethylene. PE is not particularly limited, and known polyethylenes can be used. Examples of polyethylene include at least one selected from the group consisting of HDPE (high density polyethylene), LDPE (low density polyethylene), and LLDPE (linear low density polyethylene). Preferably, the polyethylene includes HDPE (high density polyethylene). For example, "KEIYO B5804" (trade name, manufactured by Keiyo Polyethylene Co., Ltd.) can be used. PE may also be a mixture with other resins.

[0032] <Polypropylene (PP)> Polypropylene (PP) is obtained by a polymerization reaction of propylene. There are no particular limitations on the polypropylene, and known polypropylenes can be used. Examples of polypropylene include at least one selected from the group consisting of a homopolymer, which is a homopolymer of propylene alone, a random copolymer, which is a copolymer with ethylene, and a block copolymer, which is a heterophase copolymer. Preferably, the polypropylene includes a block copolymer. For example, "Prime Polypro E701G" (trade name, manufactured by Prime Polymer Co., Ltd.) can be used. Furthermore, it may be a mixture with other resins.

[0033] The content of polyethylene or polypropylene in the pellets or preforms is not particularly limited, but is preferably 80% by mass or more, more preferably 90% by mass or more, based on the mass of the pellets or preforms. It is also preferably 99.9% by mass or less, more preferably 99.5% by mass or less. For example, it is preferably in the range of 80 to 99.9% by mass or 90 to 99.5% by mass.

[0034] <Carbodiimide Compound> A carbodiimide compound has at least one carbodiimide group in its molecule. Examples of carbodiimide compounds include carbodiimide and polycarbodiimide. Carbodiimide and polycarbodiimide have at least one carbodiimide group represented by "-N=C=N-" in their molecule. Among these, it is preferable to use a polycarbodiimide having two or more carbodiimide groups in its molecule, which is expected to interact (react) more efficiently with wax-derived components.

[0035] In the polycarbodiimide compound shown in FIG. 8, n represents an integer of 1 or greater, and R2 represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound, having a benzene-based aromatic ring directly bonded to an NCN group, with either no substituents or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. Furthermore, R11 and R12 each independently represent a residue of an organic compound having one functional group capable of reacting with an isocyanate group. Such a polycarbodiimide is available, for example, under the trade name "Carbodilite HMV-15CA" (manufactured by Nisshinbo Chemical Inc.).

[0036] Polycarbodiimides can be produced, for example, by heating an organic isocyanate in the presence of a catalyst and subjecting it to a decarboxylation condensation reaction. Examples of such organic isocyanates include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. Specific examples of polycarbodiimides include aromatic polycarbodiimides such as poly(4,4'-diphenylmethanecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(diisopropylphenylcarbodiimide), and poly(triisopropylphenylcarbodiimide); and alicyclic polycarbodiimides such as poly(dicyclohexylmethanecarbodiimide). These polycarbodiimides may be used alone or in any combination of two or more.

[0037] Among these polycarbodiimides, aliphatic polycarbodiimides are preferred. Examples of aliphatic polycarbodiimides that can be used include those commercially available under the trade names "Carbodilite HMV-15CA," "Carbodilite LA-1," and "Carbodilite HMV-5CA-LC" (all of which are trade names manufactured by Nisshinbo Chemical Inc.).

[0038] In order to sufficiently react the wax-derived component with the carbodiimide compound, it is preferable to melt-knead a resin mixture containing the wax-derived component and the carbodiimide compound. Melt-kneading is thought to more easily promote the reaction between the wax-derived component and the carbodiimide compound. The melt-kneaded product thus obtained can be formed into pellets or preforms, which can then be blow-molded to obtain a blow-molded product.

[0039] Non-limiting examples of methods for obtaining pellets and preforms include the following. For example, a mixture containing at least wax, polyethylene or polypropylene, and a carbodiimide compound can be melt-kneaded, and the resulting melt-kneaded mixture can be pelletized to form pellets. Alternatively, the pellets obtained by the above method can be melt-kneaded and then molded to produce a preform.

[0040] The mode of adding the carbodiimide compound is not particularly limited. For example, a powdered carbodiimide compound can be used. For example, pellets can be formed by melt-kneading wax-containing MR-PE or MR-PP. A toner bottle containing polyethylene or polypropylene to which wax-containing toner has adhered may be pulverized, and a carbodiimide compound may be added to the resulting pulverized material and melt-kneaded to form pellets. The resulting pellets can be blow-molded by the method described below to produce a blow-molded article. That is, the process of obtaining a blow-molded article by blow-molding a resin mixture preferably includes a process of obtaining pellets of a melt-kneaded resin mixture and a process of direct blow-molding the pellets.

[0041] Furthermore, the pellets obtained by the above method can be melt-kneaded and then molded to produce a preform. The method for molding the preform will be described later. The obtained preform can be blow-molded by the method described later to produce a blow-molded article. That is, the process of blow-molding a resin mixture to obtain a blow-molded article preferably includes the steps of obtaining pellets of a melt-kneaded resin mixture, producing a preform using the pellets, and blow-molding the preform.

[0042] Because carbodiimide compounds such as polycarbodiimide are highly reactive, it is preferable to stabilize the physical properties of the reaction product between the wax-derived component and the carbodiimide compound while controlling the amount of the carbodiimide compound added. For example, the carbodiimide compound may be diluted in advance with polyethylene or polypropylene and melt-kneaded at a temperature equal to or higher than the melting point of the polyethylene or polypropylene to prepare masterbatch pellets (second pellets). The masterbatch pellets may be mixed with pellets (first pellets) containing wax and polyethylene or polypropylene to form a pellet mixture that is melt-kneaded.

[0043] It is preferable that the process for producing a blow-molded article comprises the steps of melt-kneading wax and polyethylene or polypropylene to form first pellets, melt-kneading a carbodiimide compound and other polyethylene or polypropylene to form second pellets, mixing the first pellets with the second pellets to obtain a pellet mixture, and blow-molding the pellet mixture.

[0044] Specifically, for example, wax (preferably a toner containing wax) and polyethylene or polypropylene are melt-kneaded to form first pellets. The first pellets are pellets of MR-PE or MR-PP containing wax, which are obtained by melting and pelletizing pulverized used PE or PP toner bottles.

[0045] On the other hand, separately from the step of forming the first pellets, a carbodiimide compound and another polyethylene or polypropylene are melt-kneaded to form second pellets. The other polyethylene or polypropylene used in forming the second pellets is not particularly limited, and may be the same polyethylene or polypropylene as the polyethylene or polypropylene contained in the first pellets, or a different polyethylene or polypropylene.

[0046] The dilution ratio when diluting the carbodiimide compound with polyethylene or polypropylene in preparing the masterbatch pellets (second pellets) is not particularly limited. For example, the carbodiimide compound is preferably diluted 5 to 15 times with polyethylene or polypropylene, and more preferably 10 times. By setting the dilution ratio to 5 times or more, the concentration of the carbodiimide compound is within an appropriate range, making it less likely to cause unevenness. Furthermore, by setting the dilution ratio to 15 times or less, the amount of carbodiimide compound used can be kept within an appropriate range without excessively reducing the amount. In this case, the resulting masterbatch pellets contain polyethylene or polypropylene and unreacted carbodiimide compound.

[0047] Next, the masterbatch pellets (second pellets) are mixed (pellet blended) with polyethylene or polypropylene pellets (first pellets) to obtain a pellet mixture. The resulting pellet mixture is melt-kneaded at a temperature equal to or higher than the melting point of the polyethylene or polypropylene, allowing the carbodiimide compound to react more uniformly with the wax-derived component contained in the polyethylene or polypropylene pellets (first pellets). Here, pellet blending refers to a process in which multiple materials are stirred and mixed at a temperature at which the resin components do not melt, resulting in a substantially uniform state, as opposed to melt-kneading.

[0048] Next, pellets (third pellets) containing a melt-kneaded pellet mixture of the first pellets and the second pellets may be obtained, and the melt of the third pellets may be blow-molded. Alternatively, the melt of the third pellets may be molded into a preform by a method such as injection molding. Furthermore, without preparing the third pellets, the melt of the pellet mixture prepared by uniformly stirring the first pellets and the second pellets (pellet blending) using a blender or the like may be directly blow-molded. That is, a blow-molded product can be produced by blow-molding a pellet mixture of the first pellets and the second pellets using the above-mentioned method. It is preferable that the blow-molding step includes a step of injection-molding the pellet mixture.

[0049] Alternatively, the melt of the pellet mixture can be molded into a preform by a method such as injection molding. During the injection molding of the melt of the pellet mixture, shear force is applied to the melt, and therefore the resulting preform is included in the resin composition containing the melt-kneaded product according to the present disclosure. By uniformly stirring the two types of pellets before molding, the carbodiimide compound can be reacted more uniformly with the wax-derived component contained in the polyethylene or polypropylene.

[0050] As another method, a melt-kneaded mixture containing at least a wax, polyethylene or polypropylene, and a carbodiimide compound may be melt-kneaded and then molded into a preform, without pelletizing the mixture, and the resulting preform may be used as a resin mixture. For example, a toner containing wax and a toner bottle containing polyethylene or polypropylene may be pulverized, and the melt-kneaded mixture of the pulverized mixture may be directly molded into a preform. Another method includes, for example, a method in which the melt-kneaded mixture is not pelletized, but is melt-kneaded and then molded into a blow-molded product.

[0051] The amount of the carbodiimide compound added is preferably 220 parts by mass or more, more preferably 400 parts by mass or more, and even more preferably 450 parts by mass or more, per 100 parts by mass of wax. It is also preferably 10,000 parts by mass or less, more preferably 1,500 parts by mass or less, and even more preferably 1,400 parts by mass or less. The amount of the carbodiimide compound added per 100 parts by mass of wax is, for example, preferably 220 to 10,000 parts by mass, more preferably 400 to 1,500 parts by mass, and even more preferably 450 to 1,400 parts by mass. By setting the amount of the carbodiimide compound added within the above range, the wax-derived components and the carbodiimide compound can be reacted sufficiently and reliably.

[0052] When the amount of carbodiimide compound added per 100 parts by mass of wax is 220 parts by mass or more, the reaction between the carbodiimide compound and the wax-derived components proceeds sufficiently. As a result, migration of the wax-derived components to the surface of the blow-molded article is easily suppressed, which is preferable. Furthermore, when the amount of carbodiimide compound added per 100 parts by mass of wax is 10,000 parts by mass or less, the reaction between the carbodiimide compound and the wax-derived components is kept within a range that does not cause excessive reaction, and the viscosity of the polyethylene or polypropylene when melted is not too high, and can be kept within an appropriate range. As a result, molding defects due to reduced resin fluidity during blow molding are less likely to occur, which is preferable. By adding the carbodiimide compound in the above range, it is possible to suppress migration of wax to the surface of the molded article while maintaining moldability during blow molding.

[0053] Examples of a method for reacting a carbodiimide compound with a wax-derived component include a method in which a mixture of a carbodiimide compound or masterbatch pellets containing a carbodiimide compound and polyethylene or polypropylene containing wax is heated to a temperature equal to or higher than the melting point of the polyethylene or polypropylene using an extruder to melt and knead the mixture.

[0054] The means for melt-kneading is not particularly limited, and known means such as a twin-screw extruder can be used. An example of a twin-screw extruder that can be used is "PCM-46" (trade name, manufactured by Ikegai Corporation). The temperature during melt-kneading is not particularly limited, but is preferably 180 to 260°C, more preferably 190 to 250°C, and even more preferably 200 to 240°C. By melt-kneading, the wax is hydrolyzed, and the decomposed wax becomes more reactive with carbodiimide. It is also believed that the reaction between the decomposed wax and the carbodiimide compound is more easily promoted.

[0055] The wax contained in the toner is not particularly limited, and may be any wax commonly used in toners. Specific examples of waxes include aliphatic hydrocarbon waxes such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, polyolefin copolymers, polyolefin wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax; or block copolymers thereof; vegetable waxes such as candelilla wax, carnauba wax, Japan wax, and jojoba wax; animal waxes such as beeswax, lanolin, and spermaceti; mineral waxes such as ozokerite, ceresin, and petrolactam; waxes mainly composed of aliphatic esters such as Montan acid ester wax and castor wax; and partially or completely deoxidized aliphatic esters such as deoxidized carnauba wax.Further, saturated straight-chain fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkylcarboxylic acids having an even longer alkyl chain; unsaturated fatty acids such as brassidic acid, eleostearic acid, or valinaric acid; saturated alcohols such as stearyl alcohol, eicosyl alcohol, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, melissyl alcohol, or alkyl alcohols having an even longer alkyl chain; polyhydric alcohols such as sorbitol; aliphatic amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; saturated aliphatic bisamides such as methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, and hexamethylene bisstearic acid amide; ethylene bis(isopropyl ether)amide, ... Examples of suitable waxes include unsaturated fatty acid amides such as m-xylenebisstearamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacamide; aromatic bisamides such as m-xylenebisstearamide and N,N'-distearylisophthalamide; fatty metal salts (commonly known as metal soaps) such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; waxes obtained by grafting aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid; partial esters of fatty acids and polyhydric alcohols such as behenic acid monoglyceride; and methyl ester compounds having hydroxyl groups obtained by hydrogenating vegetable oils and fats. Rw1 in the waxes exemplified in Figures 8A and 8B represents, for example, a hydrocarbon group having 1 to 40 carbon atoms. The hydrocarbon group is typically an alkyl group.

[0056] These waxes may be used alone or in any combination of two or more. The wax preferably includes an ester wax. It is considered that the ester wax may hydrolyze during blow molding or in a toner bottle, becoming a component that deforms the toner. However, according to the method of the present disclosure, the hydrolyzate reacts with a carbodiimide compound to polymerize, preventing migration to the surface of the blow-molded article.

[0057] In addition, waxes having a sharp molecular weight distribution obtained by using a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method, a melt crystal precipitation method, or the like are preferably used. Waxes from which low-molecular-weight solid fatty acids, low-molecular-weight solid alcohols, low-molecular-weight solid compounds, and other impurities have been removed are also preferably used. Specific examples include Viscol (registered trademark) 330-P, 550-P, 660-P, and TS-200 (Sanyo Chemical Industries, Ltd.), Hiwax 400P, 200P, 100P, 410P, 420P, 320P, 220P, 210P, and 110P (Mitsui Chemicals, Inc.), Sasol H1, H2, C80, C105, and C77 (Schumann-Sasol), HNP-1, HNP-3, and HN P-9, HNP-10, HNP-11, HNP-12 (Nippon Seiro Co., Ltd.), Unilin (registered trademark) 350, 425, 550, 700, Unicid (registered trademark) 350, 425, 550, 700 (Toyo Petrolite Co., Ltd.), Japan wax, beeswax, rice wax, candelilla wax, carnauba wax (available from Cerarica NODA Co., Ltd.), and the like.

[0058] The blow-molded article may contain a colorant, if necessary. Examples of colorants include carbon black. The content of the colorant in the blow-molded article is, for example, 0.01 to 0.20% by mass, or 0.02 to 0.10% by mass.

[0059] <Stretch Blow Molding> A method for producing a blow-molded product by stretch blow molding is described below. Stretch blow molding is a method in which a preform is molded from molten raw material and then the preform is stretch-blow molded. (I) Preform Manufacturing Process The method for producing a preform is described below. As shown in FIG. 2 , a test-tube-shaped preform 104 is molded by injection molding. Specifically, a heating cylinder 105 heats a material fed into an injection molding machine 101 to a molten state, and an extrusion screw 207 injects the molten material into preform molds 102 and 103. After cooling, the material is removed from the mold to obtain the preform 104. Examples of materials that can be used include pellets containing wax (preferably a toner containing wax), polyethylene or polypropylene, and a carbodiimide compound. Alternatively, a melt-kneaded mixture containing wax (preferably a toner containing wax), polyethylene or polypropylene, and a carbodiimide compound may also be used.

[0060] In the preform molding step, it is preferable to mold the preform by injection molding. That is, it is preferable that the preform molding step includes a step of injection molding a melt-kneaded mixture of pellets. It is also preferable that the preform has a test tube shape. In the preform molding step, the raw material is melted, and the wax is hydrolyzed. The wax-derived component reacts with the carbodiimide compound, which makes the wax-derived component more likely to be polymerized.

[0061] (II) Step of stretch-blow molding a preform to produce a blow-molded article Next, a step of stretch-blow molding a preform to produce a blow-molded article will be described. As shown in Fig. 3, a preform 104 is biaxially stretch-blow molded (biaxial stretch molding). First, the preform 104 is placed in a heating furnace 107 and heated to a temperature at which it can be stretched.

[0062] The heated preform 104 is removed from the heating furnace 107 and placed in the mouth of a blow mold 108. A cavity is formed inside the blow mold 108 by combining a left mold 108-1 and a right mold 108-2. It is preferable to place the heated preform in the mouth of the blow mold in a short time (for example, within 10 seconds) so that the temperature of the heated preform does not drop before the start of the biaxial stretching process.

[0063] The heated preform placed in the blow mold 108 is stretched in the longitudinal direction of the preform using a stretch rod 109. This is called the primary stretching. In the primary stretching, it is preferable to inject gas so that the preform 104 does not come into contact with the stretch rod 109. The pressure of the gas at this time is called the primary blow pressure.

[0064] After the primary stretching, gas 110 is introduced through the preform opening 106 to stretch the preform in the lateral direction (circumferential direction, i.e., the direction intersecting the stretching rod 109). This is called secondary stretching. The pressure of the gas at this time is called secondary blow pressure. Examples of gases introduced during the primary and secondary stretching include air, nitrogen, carbon dioxide, and argon.

[0065] By carrying out these primary and secondary stretching steps, the preform 104 expands in each direction indicated by the arrows 111, adheres to the inner wall of the blow mold 108, and is cooled and solidified in this state to produce a blow-molded product 112. The step of blow-molding the preform preferably includes a step of stretching the preform in the longitudinal direction of the preform using a stretching rod, and a step of injecting gas into the longitudinally stretched preform to stretch the preform in the circumferential direction.

[0066] Next, the left mold 108-1 and the right mold 108-2 of the blow mold 108 are separated, and the blow-molded article 112 is removed from the blow mold 108. Since this blow-molded article 112 is stretched in both the vertical and horizontal directions, it becomes a molded article with high strength.

[0067] In the stretching step of injection stretch blow molding, it is preferable that the preform is in a non-crystallized state (non-crystalline, i.e., amorphous state). If the preform is maintained at the blow molding temperature in an amorphous state, blowing, i.e., biaxial stretch molding, will stretch-crystallize the PE or PP in the stretched direction, making it possible to form a bottle with high strength.

[0068] Injection stretch blow molding methods include one-stage and two-stage methods. The one-stage method is a method in which the residual heat of the preform immediately after removal from the mold is used to stretch blow mold the preform as is or after temperature control. The two-stage method is a method in which the preform is once cooled to room temperature and then the temperature of the preform is again controlled and stretch blow molded. That is, the step of molding the pellets to produce a preform and the molding step of stretch blow molding the preform to produce a stretch blow molded article may be carried out continuously while maintaining the temperature of the preform. Furthermore, after the step of molding the pellets to produce a preform, the preform may once be cooled to room temperature and then stretch blow molded to produce a stretch blow molded article.

[0069] A schematic diagram of the one-stage method is shown in Figure 4. In the one-stage method, after injection molding of a preform 104 from an injection molding machine 101, the preform 104 is immediately heated and kept at a blow molding temperature (for example, 140 to 160°C) and blow molded to produce a blow-molded product 112. The one-stage method uses an apparatus in which an injection molding apparatus and a blow molding apparatus are integrated.

[0070] In the two-stage method, the preform is injection molded, cooled, removed, and then heated to a blow molding temperature (e.g., 140 to 160°C) in a separate blow molding machine for blow molding. In the two-stage method, the injection molding machine and the blow molding machine are not integrated, but are independent machines.

[0071] The injection stretch blow molding method can be appropriately selected depending on the components contained in the preform, etc. The one-stage method is preferable in that it does not include a step of cooling the preform and therefore requires less energy for reheating than the two-stage method.

[0072] <Direct Blow Molding> A method for producing a blow-molded product by direct blow molding will be described below. Direct blow molding is a method in which molten raw materials or pellets formed from raw materials are directly blow-molded. Direct blow molding involves blow-molding a molten resin mixture using an injection molding machine or the like. Materials used in direct blow molding can include pellets containing at least wax (preferably a toner containing wax), polyethylene or polypropylene, and a carbodiimide compound. Alternatively, a melt-kneaded resin mixture containing wax, polyethylene or polypropylene, and a carbodiimide compound can be used.

[0073] One embodiment of a method for producing a blow-molded product by direct blow molding is described below. As shown in FIG. 5 , a resin mixture (the pellets or a molten mixture of raw materials) is loaded into a direct blow molding machine 301, where it is heated and melt-kneaded while dripping under its own weight into a cylindrical shape. Before the molten mixture cools and solidifies, it is sandwiched between molds 302 and simultaneously inflated with a gas from blow pins 303. Examples of gases include air, nitrogen, carbon dioxide, and argon. That is, a method for producing a blow-molded product by direct blow molding preferably includes a step of sandwiching the molten mixture between molds and injecting a gas to stretch the resin mixture. By stretching the molten resin mixture with the gas, the resin mixture adheres to the inner wall of the blow mold and is cooled and solidified in that state. Finally, the blow mold is opened, and the blow-molded product is removed from the blow mold. The resin contained in the resin mixture is stretched by this blow molding, resulting in a molded product with high strength.

[0074] Next, a method for checking chemical attack in toner contained in a toner bottle obtained by blow molding will be described. Toner is placed in a toner bottle obtained by blow molding. The toner bottle containing the toner is left in a usage environment. In the evaluation of chemical attack according to the present disclosure, the usage environment is set to 50°C for 72 hours, and the toner bottle is left in a test thermostatic chamber. The toner bottle exposed to the usage environment is removed, and only the toner adhering to the inner surface of the bottle is extracted and observed under an electron microscope. In the present disclosure, the toner is discharged from the bottle with the opening facing downward, and then the toner adhering to the inner surface of the bottle is attached to adhesive tape, and only the toner adhering to the inner surface of the bottle is extracted. When the deformation of the toner particle surface of the toner adhering to the inner surface of the bottle is observed under an electron microscope, toner particles that have undergone chemical attack can be observed as deformed areas at the contact surface with the toner bottle. The deformed areas at the contact surface with the toner bottle can be identified by the fact that they have less unevenness in the electron microscope image compared to the surrounding areas.

[0075] (Image forming apparatus) An image forming apparatus using a toner storage bottle obtained by the manufacturing method of the present disclosure will be described below with reference to the drawings. Fig. 1 is a schematic diagram illustrating the configuration of a four-color image forming apparatus using an electrophotographic system, and in the figure, reference numeral 80 indicates the main body of the image forming apparatus. The image forming apparatus 80 is configured as a so-called intermediate transfer tandem type image forming apparatus, in which four color image forming units are arranged side by side on an intermediate transfer belt.

[0076] The image forming apparatus 80 forms an image as follows: First, in the image forming apparatus 80, an electrostatic latent image is formed on the photosensitive drum 17 (17y, 17m, 17c, 17bk) by the exposure device 50 (50y, 50m, 50c, 50bk) based on print data. Then, the formed electrostatic latent image is developed by the developing device 21 (21y, 21m, 21c, 21bk) to form a toner image.

[0077] The toner image is transferred onto an intermediate transfer body 62 by a primary transfer device 60 (60y, 60m, 60c, 60bk), and then transferred onto a sheet material S supplied from a paper feed device 63 in a secondary transfer section 64 (64a, 64b). Next, the toner image transferred onto the sheet material S is fixed onto the sheet material S by a fixing means 68, and then the sheet is discharged onto a paper discharge tray 70.

[0078] In the image forming apparatus 80, a toner image is formed by developing the image in the developing device 21 as described above. At this time, detachable toner bottles 3 (3Y, 3M, 3C, 3Bk) can be used to supply toner to the developing device 21. The toner bottles manufactured by the manufacturing method of the present disclosure are toner bottles used in this manner.

[0079] The present disclosure will be described in detail below using examples and comparative examples. However, the present disclosure is not limited to these examples. In the following examples and comparative examples, "%" means "% by mass" unless otherwise specified.

[0080] (Examples A1 to A12, Comparative Examples A1 and A2) <Preparation of toner bottle by stretch blow molding> A toner bottle (total length (B) 439.5 mm, diameter (A) 101 mm) shown in FIG. 7 was prepared using a one-stage stretch blow molding apparatus (ASB-70DPH manufactured by Nissei ASB Machinery Co., Ltd.). The blow stretch ratio was "longitudinal ratio x lateral ratio = 6.7". The "longitudinal ratio" of the blow stretch ratio is a value calculated by dividing the "total length after stretching" by the "total length (before stretching) of the portion (heated portion) of the preform that reaches the stretching temperature". The "lateral ratio" of the blow stretch ratio is a value calculated by dividing the "diameter of the intermediate portion after stretching" by the "diameter of the intermediate portion of the preform (before stretching)".

[0081] First, the materials shown in Table 1 below were melt-kneaded and then pelletized to prepare a masterbatch having a carbon black concentration of 5% by mass.

[0082] Next, the masterbatch having a carbon black concentration of 5% by mass prepared above and PP were mixed in the ratios shown in Table 2 below, melt-kneaded, and then pelletized to obtain pellets as a resin mixture.

[0083] <Blow Molding Conditions> The pellets as the resin mixture were fed into an extrusion molding device of a one-stage stretch blow molding machine (product name: ASB-70DPH; manufactured by Nissei ASB Machinery Co., Ltd.), and a toner bottle was molded by biaxial stretch blow molding. The one-stage stretch blow molding machine is capable of continuously carrying out a step of manufacturing a test tube-shaped preform by injection molding and a step of manufacturing a bottle-shaped molded product by biaxial stretch blow molding the preform. The screw diameter of the injection molding machine in this molding machine was 54 mm.

[0084] First, a mold capable of molding a preform with an outer diameter of 30 mm, a wall thickness of 3.7 mm, and a length of 220 mm was prepared as a mold for molding a preform. Then, a preform was molded under the following molding conditions. Screw diameter: 54 mm Screw position before filling the resin mixture into the cavity: 95 mm Injection speed Until the screw advances 5 mm: 50% of the maximum speed Until the screw advances another 20 mm: 30% of the maximum speed Until the screw advances another 35 mm: 25% of the maximum speed PV switching position: 35 mm First stage of holding pressure: 30 MPa, 4 s Second stage of holding pressure: 20 MPa, 7.99 s Heating barrel temperature: 230 ° C. Cooling time: 10.0 seconds Mold temperature: 20 ° C.

[0085] After a cooling time of 10.0 seconds had elapsed, the preform was demolded and transported to the biaxial stretch blow station of the one-stage stretch blow molding machine. The temperature of the preform during transport was controlled as follows: Preform heating temperature: 180°C at a position 10% of the total length of the preform from the top; 200°C at a position 25% of the total length of the preform from the top; 200°C at a position 50% of the total length of the preform from the top; and 180°C at a position 75% of the total length of the preform from the top.

[0086] The preform adjusted to the above temperature was then placed in a cylindrical mold adjusted to a temperature of 20°C and corresponding to the size of the toner bottle, and biaxially stretched and blow-molded to produce a blown bottle. The preform was heated during transport to adjust its temperature, and the surface temperature of the preform's center was 150°C immediately before being placed in the cylindrical mold. First, the stretch bar, which was in a retracted position, was inserted into the preform through its opening and advanced until it contacted the top of the preform. Next, the air pressure driving the stretch bar was increased to 1.2 MPa, and the stretch bar was further advanced. Next, 0.5 seconds after the start of further advancement of the stretch bar, primary air was introduced into the preform through its opening. The pressure of the primary air was set to 0.4 MPa. Next, 0.7 seconds after the introduction of the primary air, secondary air was introduced. The pressure of the secondary air was set to 1.2 MPa. Air was then introduced into the preform over 2.7 seconds from the start of the introduction of the primary air. The pressure inside the preform was then returned to normal pressure over 0.5 seconds. In this way, a toner bottle was produced by blow molding. This bottle is a toner bottle containing virgin PP that has not been recycled. 200 toner bottles containing virgin PP were prepared using the method described above.

[0087] Example A1 Preparation of Recycled Pellets All 200 toner bottles containing virgin PP prepared above were filled with black toner contained in an electrophotographic toner bottle (product name: Toner NPG-67; manufactured by Canon Inc.). The black toner contained 6.9 parts by weight of ester wax per 100 parts by weight of toner. Next, the black toner filled in the toner bottles containing virgin PP was discharged by pointing the opening of the toner bottle vertically downward. Even after this operation, a small amount of black toner remained on the inner wall of each toner bottle. At this time, the average amount of black toner remaining in the toner bottles for the 200 toner bottles was 0.321% by weight, based on the weight of the toner bottle itself. Note that the weight of the toner bottle itself refers to the weight of the toner bottle and the toner remaining therein, with all supply components and other items removed.

[0088] Next, 200 of the toner bottles with toner adhering thereto prepared as described above were crushed in a crusher to a size of approximately 5 to 10 mm square to obtain crushed products (hereinafter also referred to as flake products). These flake products were melt-kneaded using a twin-screw extruder (PCM-46 manufactured by Ikegai Corporation) at a temperature of 210°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, and then pelletized. The obtained recycled pellets were designated MR-PP (1-1) (first pellets).

[0089] <Preparation of Blow Bottles> A polycarbodiimide compound was added to MR-PP (1-1), and biaxial stretch blow molding was carried out using the one-stage stretch blow molding apparatus described above under the same blow molding conditions as described above. The polycarbodiimide compound was diluted and prepared in advance as masterbatch pellets to facilitate uniform mixing in a blender. Specifically, the polycarbodiimide compound and PP were mixed in the proportions shown in Table 3, melt-kneaded, and then pelletized to prepare polycarbodiimide masterbatch pellets (second pellets).

[0090] Before loading the materials into the molding machine, 3.0% by mass of polycarbodiimide masterbatch pellets (second pellets) were added to MR-PP (1-1) (first pellets) and uniformly stirred in a blender to form a pellet mixture. The polycarbodiimide masterbatch pellets were diluted to the ratio shown in Table 3, so the polycarbodiimide content was essentially 0.3% by mass. The pellet mixture stirred in the blender was loaded into the blow molding machine and subjected to biaxial stretch blow molding under the same blow molding conditions as described above. The resulting toner bottle was designated toner bottle (1-1A). Toner was placed in toner bottle (1-1A) and left in an operating environment at 50°C for 72 hours. The toner adhering to the inner surface of the toner bottle was then removed, and the surface of the toner particles was observed under an electron microscope. No deformation of the toner particle surface was observed, confirming that no chemical attack had occurred.

[0091] (Examples A2 and A3) Toner bottles (1-2A) and (1-3A) were produced in the same manner as in Example A1, except that the compounding ratio of MR-PP (1-1) and polycarbodiimide masterbatch was changed as shown in Table 4. Using toner bottles (1-2A) and (1-3A), occurrence of chemical attack was checked in the same procedure as for toner bottle (1-1A), and it was confirmed that no chemical attack occurred. For the toner bottles (1-1A), (1-2A), and (1-3A), the toner bottles were crushed and melt-kneaded to form first pellets, which were then mixed with second pellets (master batch pellets) of a polycarbodiimide compound prepared in advance before being introduced into a molding machine.

[0092] (Example A4) <Preparation of Recycled Pellets> 0.3% by mass of a polycarbodiimide compound (trade name: Carbodilite HMV-15CA; manufactured by Nisshinbo Chemical Inc.) was uniformly added to flakes prepared in the same manner as in Example A1, and the mixture was melt-kneaded using a twin-screw extruder (manufactured by Ikegai Corporation, PCM-46) at a temperature of 210°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, followed by pelletization. The polycarbodiimide used here was in powder form and was not a masterbatch pellet. The resulting recycled pellets were designated MR-PP (2-1).

[0093] <Preparation of blown bottle> MR-PP (2-1) was placed in the one-stage blow molding machine and biaxial stretch blow molding was carried out under the same blow molding conditions as above. Because polycarbodiimide was added during the extrusion process of MR-PP (2-1), unlike Examples A1 to A3, polycarbodiimide was not added when the material was placed in the blow molding machine. The resulting toner bottle was named toner bottle (2-1A).

[0094] Examples A5 and A6 Pellets of MR-PP (2-2) and (2-3) were prepared in the same manner as for MR-PP (2-1), except that the blending ratio of polycarbodiimide in Example A4 was changed as shown in Table 5.

[0095] Each of the obtained pellets was subjected to biaxial stretch blow molding under the same conditions as in Example A4 to obtain toner bottles (2-2A) and (2-3A). Toner was placed in each bottle, and after leaving it at 50°C for 72 hours, deformation of the toner particle surface of the toner adhering to the inner surface of the toner bottle was observed. Toner bottle (2-2A) was evaluated as Example A5, and toner bottle (2-3A) was evaluated as Example A6. As a result, no deformation of the toner particle surface was confirmed in Examples A4 to A6, confirming that no chemical attack had occurred.

[0096] In Examples A4 to A6, no masterbatch pellets were prepared, and instead, a carbodiimide compound was added when pulverized toner bottles (flakes) with toner attached were melt-kneaded and pelletized in an extruder. It is believed that this method sufficiently kneaded the wax and carbodiimide compound in the extruder, allowing the reaction between the wax and the carbodiimide compound to proceed sufficiently. Therefore, it is believed that migration of the wax to the inner surface of the toner bottle was sufficiently prevented, suppressing chemical attack. Table 6 shows the evaluation results of chemical attack after molding the toner bottles for Examples A4 to A6. As described above, polycarbodiimide was added to the toner bottles (2-1A), (2-2A) and (2-3A) in the process of crushing the toner bottles, melting and kneading them to form pellets.

[0097] (Comparative Example A1) <Preparation of Recycled Pellets> Flakes prepared in the same manner as in Example A1 were melt-kneaded using a twin-screw extruder (PCM-46 manufactured by Ikegai Corporation) at a temperature of 210°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, and then pelletized. No polycarbodiimide compound was added during melt-kneading. The resulting recycled pellets were designated MR-PP (2-4).

[0098] <Preparation of Blow Bottle> MR-PP (2-4) was placed in the one-step stretch blow molding machine and biaxially stretched blow molding was carried out under the same blow molding conditions as above. The obtained toner bottle was designated as toner bottle (2-4A). Toner was placed in toner bottle (2-4A) and left in the usage environment (50°C, 72 hours) to carry out an environmental test. After the test, the toner adhering to the inner surface of the toner bottle was observed by the above-mentioned method, and deformation of the toner particle surface was confirmed, confirming the occurrence of chemical attack.

[0099] <Production of Toner Bottle by Direct Blow Molding> A toner bottle (total length (B) 150 mm, diameter (A) 76 mm) shown in FIG. 7 was produced using a direct blow molding machine (model name: MSE-55E / 54M-AP(E2), Tahara Corporation).

[0100] First, the materials shown in Table 8 below were melt-kneaded and then pelletized to prepare a masterbatch having a carbon black concentration of 5% by mass. Next, the masterbatch having a carbon black concentration of 5% by mass prepared above and PP were mixed in the ratios shown in Table 9 below, melt-kneaded, and then pelletized to obtain pellets as a resin mixture.

[0101] <Direct Blow Molding Conditions> The pellets as the resin mixture described above were charged into a direct blow molding machine (model name: MSE-55E / 54M-AP(E2), Tahara Co., Ltd.) to mold a toner bottle. The screw diameter of the injection molding machine in the molding machine was 50 mm.

[0102] Direct blow molding was performed under the following molding conditions: Extruder screw diameter: 50 mm Extruder cylinder temperature: 210°C Extrusion rate: 10 kg / h Blow pressure: 0.6 MPa Cooling time: 15 s Mold temperature: 15°C A toner bottle was produced by the above direct blow molding. This bottle is a toner bottle made from virgin PP that has not been recycled. 200 toner bottles made from virgin PP were produced using the above method.

[0103] Example A7 Preparation of Recycled Pellets All 200 toner bottles containing virgin PP prepared above were filled with black toner contained in an electrophotographic toner bottle (product name: Toner NPG-67; manufactured by Canon Inc.). The black toner contained 6.9 parts by weight of ester wax per 100 parts by weight of toner. Next, the black toner filled in the toner bottle containing virgin PP was discharged by pointing the opening of the toner bottle vertically downward. Even after this operation, a small amount of black toner remained on the inner wall of each toner bottle. At this time, the average amount of black toner remaining in the toner bottle for the 200 toner bottles was 0.321% by weight, based on the weight of the toner bottle itself. Note that the weight of the toner bottle itself refers to the weight of the toner bottle and the toner remaining therein, with all supply components and other items removed.

[0104] Next, 200 of the toner bottles with toner adhering to the interior of the bottles prepared above were crushed using a crusher to obtain crushed products (hereinafter also referred to as "flake products") in sizes of approximately 5 to 10 mm square. The wax content per 100 parts by mass of the resulting flake products was 0.022 parts by mass. The wax content in the flake products was measured using GPC and FT-IR. Next, the above flake products were melt-kneaded using a twin-screw extruder (PCM-46 manufactured by Ikegai Corporation) at a temperature of 210°C, a screw rotation speed of 200 rpm, vent degassing pressure of -0.08 MPa, and a discharge rate of 50 kg / h, and then pelletized. The resulting recycled pellets were designated MR-PP (3-1) (first pellets).

[0105] <Preparation of blown bottles> A polycarbodiimide compound was added to MR-PP (3-1), and direct blow molding was carried out under the same blow molding conditions as described above. The polycarbodiimide compound was diluted and prepared in advance as masterbatch pellets to facilitate uniform mixing in a blender. Specifically, the polycarbodiimide compound and PP were mixed in the proportions shown in Table 10, melt-kneaded, and then pelletized to prepare polycarbodiimide masterbatch pellets (second pellets).

[0106] Before loading the materials into the molding machine, 3.0% by mass of polycarbodiimide masterbatch pellets (second pellets) were added to MR-PP (3-1) (first pellets) and uniformly stirred in a blender to form a pellet mixture. The polycarbodiimide masterbatch pellets were diluted to the ratio shown in Table 10, so the polycarbodiimide content was essentially 0.3% by mass. The pellet mixture stirred in the blender was loaded into the blow molding machine and subjected to direct blow molding under the same blow molding conditions as described above. The resulting toner bottle was designated toner bottle (3-1A). Toner was placed in toner bottle (3-1A) and left in an operating environment at 50°C for 72 hours. The toner adhering to the inner surface of the toner bottle was then removed, and the surface of the toner particles was observed under an electron microscope. No deformation of the toner particle surface was observed, confirming that no chemical attack had occurred.

[0107] (Examples A8 and A9) Toner bottles (3-2A) and (3-3A) were produced in the same manner as in Example A7, except that the compounding ratio of MR-PP (3-1) and polycarbodiimide masterbatch was changed as shown in Table 11. Using toner bottles (3-2A) and (3-3A), occurrence of chemical attack was checked in the same procedure as for toner bottle (3-1A), and it was confirmed that no chemical attack occurred. For the toner bottles (3-1A), (3-2A), and (3-3A), the toner bottles were crushed and melt-kneaded to form first pellets, which were then mixed with second pellets (master batch pellets) of a polycarbodiimide compound prepared in advance before being introduced into a molding machine.

[0108] (Example A10) <Preparation of Recycled Pellets> 0.3% by mass of a polycarbodiimide compound (trade name: Carbodilite HMV-15CA; manufactured by Nisshinbo Chemical Inc.) was uniformly added to flakes prepared in the same manner as in Example A7, and the mixture was melt-kneaded using a twin-screw extruder (manufactured by Ikegai Corporation, PCM-46) at a temperature of 210°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, followed by pelletization. The polycarbodiimide used here was in powder form and was not a masterbatch pellet. The resulting recycled pellets were designated MR-PP (4-1).

[0109] <Preparation of blown bottle> MR-PP (4-1) was placed in the above-mentioned direct blow molding machine, and direct blow molding was carried out under the same blow molding conditions as those described above. Because polycarbodiimide was added during the extrusion process of MR-PP (4-1), unlike Examples A7 to A9, polycarbodiimide was not added when the material was placed in the blow molding machine. The resulting toner bottle was named toner bottle (4-1A).

[0110] (Examples A11 and A12) Pellets of MR-PP (4-2) and (4-3) were prepared in the same manner as for MR-PP (4-1), except that the blending ratio of polycarbodiimide in Example A10 was changed as shown in Table 12.

[0111] Each of the obtained pellets was subjected to direct blow molding under the same conditions as in Example A10 to obtain toner bottles (4-2A) and (4-3A). Toner was placed in each bottle, and after leaving it at 50°C for 72 hours, deformation of the toner particle surface of the toner adhering to the inner surface of the toner bottle was observed. Toner bottle (4-2A) was evaluated as Example A11, and toner bottle (4-3A) was evaluated as Example A12. As a result, no deformation of the toner particle surface was confirmed in Examples A10 to A12, confirming that no chemical attack had occurred.

[0112] In Examples A10 to A12, no masterbatch pellets were prepared, and instead, a carbodiimide compound was added when pulverized toner bottles (flakes) with toner attached thereto were melt-kneaded and pelletized in an extruder. It is believed that this method sufficiently kneaded the wax and carbodiimide compound in the extruder, allowing the reaction between the wax and the carbodiimide compound to proceed sufficiently. It is believed that this sufficiently prevented the wax from migrating to the inner surface of the toner bottle, thereby suppressing chemical attack. Table 13 shows the evaluation results of chemical attack after molding the toner bottles for Examples A10 to A12. As described above, polycarbodiimide was added to the toner bottles (4-1A), (4-2A) and (4-3A) in the process of crushing the toner bottles, melting and kneading them to form pellets.

[0113] (Comparative Example A2) <Preparation of Recycled Pellets> Flakes prepared in the same manner as in Example A7 were melt-kneaded using a twin-screw extruder (PCM-46 manufactured by Ikegai Corporation) at a temperature of 210°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, and then pelletized. No polycarbodiimide compound was added during melt-kneading. The resulting recycled pellets were designated MR-PP (4-4).

[0114] <Preparation of Blow Bottle> MR-PP (4-4) was placed in the above-mentioned direct blow molding machine and subjected to direct blow molding under the same blow molding conditions as above. The obtained toner bottle was designated as toner bottle (4-4A). Toner was placed in toner bottle (4-4A) and left in a usage environment (50°C, 72 hours) to carry out an environmental test. After the test, the toner adhering to the inner surface of the toner bottle was observed by the above-mentioned method, and deformation of the toner particle surface was confirmed, confirming the occurrence of chemical attack.

[0115] (Examples B1 to B6, Comparative Example B1) <Production of toner bottles by direct blow molding> Toner bottles shown in Fig. 7 were produced using a direct blow molding device. A was 76 mm in diameter, and B was 150 mm. KEIYO B5804 (product name) manufactured by Keiyo Polyethylene Co., Ltd. was used as the pellet material.

[0116] First, the materials shown in Table 15 below were melt-kneaded and then pelletized to prepare a masterbatch having a carbon black concentration of 5% by mass.

[0117] Next, the masterbatch with a carbon black concentration of 5% by mass prepared above and PE were mixed in the ratios shown in Table 16 below, melt-kneaded, and then pelletized to obtain pellets of a resin mixture.

[0118] <Blow Molding Conditions> The pellets of the resin mixture were charged into a direct blow molding machine (model name: MSE-55E / 54M-AP(E2), Tahara Co., Ltd.) to mold a toner bottle. The screw diameter of the injection molding machine in the molding machine was 50 mm.

[0119] Direct blow molding was performed under the following molding conditions: Extruder screw diameter: 50 mm Extruder cylinder temperature: 182°C Extrusion rate: 10 kg / h Blow pressure: 0.6 MPa Cooling time: 15 s Mold temperature: 15°C A toner bottle was produced by the above direct blow molding. This bottle is a toner bottle made from virgin PE that has not been recycled. 200 toner bottles made from virgin PE were produced using the above method.

[0120] (Example B1) <Preparation of Recycled Pellets> All 200 toner bottles containing virgin PE prepared above were filled with black toner contained in a toner cartridge (product name: Toner NPG-26, manufactured by Canon Inc.). The black toner contained ester wax. Next, the openings of the toner bottles containing virgin PE were turned vertically downward to discharge the black toner inside. Even after this operation, a small amount of black toner remained on the inner wall of each toner bottle. At this time, the average amount of black toner remaining in the toner bottles for the 200 toner bottles was 0.321% by mass, based on the mass of the toner bottle itself. Note that the mass of the toner bottle itself refers to the mass of the toner bottle and the toner remaining inside, with all supply components and other items removed from the toner bottle.

[0121] Next, each of the toner bottles with toner adhering to the inner surface was crushed in a crusher to a size of approximately 5 to 10 mm square to obtain crushed products (hereinafter also referred to as flake products). These flake products were melt-kneaded using a twin-screw extruder (PCM-46 manufactured by Ikegai Corporation) at a temperature of 200°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, and then pelletized. The obtained recycled pellets were designated MR-PE (1-1) (first pellets).

[0122] <Preparation of blown bottles> A polycarbodiimide compound was added to MR-PE (1-1), and direct blow molding was carried out under the same blow molding conditions as described above. The polycarbodiimide compound was diluted and prepared in advance as masterbatch pellets to facilitate uniform mixing in a blender. Specifically, the polycarbodiimide compound and PE were mixed in the proportions shown in Table 17, melt-kneaded, and then pelletized to prepare polycarbodiimide masterbatch pellets (second pellets).

[0123] Before loading the materials into the molding machine, 3.0% by mass of polycarbodiimide masterbatch pellets (second pellets) were added to MR-PE (1-1) (first pellets) and uniformly stirred in a blender to form a pellet mixture. The polycarbodiimide masterbatch pellets were diluted to the ratio shown in Table 17, so the polycarbodiimide content was essentially 0.3% by mass. The pellet mixture stirred in the blender was subjected to direct blow molding under the same blow molding conditions as described above. The resulting toner bottle was designated toner bottle (1-1B). Toner was placed in toner bottle (1-1B) and left in an operating environment at 50°C for 72 hours. The toner adhering to the inner surface of the toner bottle was then removed, and the surface of the toner particles was observed under an electron microscope. No deformation of the toner particle surface was observed, confirming that no chemical attack had occurred.

[0124] (Examples B2 and B3) Toner bottles (1-2B) and (1-3B) were produced in the same manner as in Example B1, except that the compounding ratio of MR-PE (1-1) and the polycarbodiimide masterbatch was changed as shown in Table 18. Using toner bottles (1-2B) and (1-3B), the occurrence of chemical attack was checked using the same procedure as for toner bottle (1-1B), and it was confirmed that no chemical attack occurred. For the toner bottles (1-1B), (1-2B), and (1-3B), the toner bottles were crushed and melt-kneaded to form first pellets, which were then mixed with second pellets (master batch pellets) of a polycarbodiimide compound prepared in advance before being introduced into a molding machine.

[0125] (Example B4) <Preparation of Recycled Pellets> 0.3% by mass of a polycarbodiimide compound (trade name: Carbodilite HMV-15CA; manufactured by Nisshinbo Chemical Inc.) was uniformly added to flakes prepared in the same manner as in Example B1, and the mixture was melt-kneaded using a twin-screw extruder (manufactured by Ikegai Corporation, PCM-46) at a temperature of 200°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, followed by pelletization. The polycarbodiimide used here was in powder form and was not a masterbatch pellet. The resulting recycled pellets were designated MR-PE (2-1).

[0126] <Preparation of blown bottle> MR-PE (2-1) was subjected to direct blow molding under the same blow molding conditions as above. Because polycarbodiimide was added during the extrusion process of MR-PE (2-1), unlike Examples B1 to B3, polycarbodiimide was not added when the material was fed into the blow molding machine. The resulting toner bottle was designated toner bottle (2-1B).

[0127] Examples B5 and B6 Pellets of MR-PE (2-2) and (2-3) were prepared in the same manner as for MR-PE (2-1), except that the blending ratio of polycarbodiimide in Example B4 was changed as shown in Table 19.

[0128] Each of the obtained pellets was subjected to direct blow molding under the same conditions as in Example B4 to obtain toner bottles (2-2B) and (2-3B). Toner was placed in each bottle, and after leaving it at 50°C for 72 hours, deformation of the toner particle surface of the toner adhering to the inner surface of the toner bottle was observed. Toner bottle (2-2B) was evaluated as Example B5, and toner bottle (2-3B) was evaluated as Example B6. As a result, no deformation of the toner particle surface was confirmed in Examples B4 to B6, confirming that no chemical attack had occurred.

[0129] In Examples B4 to B6, no masterbatch pellets were prepared, and instead, a carbodiimide compound was added when pulverized toner bottles (flakes) with toner attached were melt-kneaded and pelletized in an extruder. It is believed that this method sufficiently kneaded the wax and carbodiimide compound in the extruder, allowing the reaction between the wax and the carbodiimide compound to proceed sufficiently. This sufficiently prevented the wax from migrating to the inner surface of the toner bottle, suppressing chemical attack. Table 20 shows the evaluation results of chemical attack after molding the toner bottles for Examples B4 to B6. As described above, polycarbodiimide was added to the toner bottles (2-1B), (2-2B) and (2-3B) in the process of crushing, melting and kneading the toner bottles to form pellets.

[0130] (Comparative Example B1) <Preparation of Recycled Pellets> Flakes prepared in the same manner as in Example B1 were melt-kneaded using a twin-screw extruder (PCM-46 manufactured by Ikegai Corporation) at a temperature of 200°C, a screw rotation speed of 200 rpm, vent degassing of -0.08 MPa, and a discharge rate of 50 kg / h, and then pelletized. No polycarbodiimide compound was added during melt-kneading. The resulting recycled pellets were designated MR-PE (2-4).

[0131] <Preparation of Blow Bottle> MR-PE (2-4) was subjected to direct blow molding under the same blow molding conditions as described above. The resulting toner bottle was designated as toner bottle (2-4B). Toner was placed in toner bottle (2-4B) and left in a usage environment (50°C, 72 hours) to conduct an environmental test. After the test, the toner adhering to the inner surface of the toner bottle was observed using the above-described method, and deformation of the toner particle surface was confirmed, confirming the occurrence of chemical attack.

[0132] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to clarify the scope of the present disclosure. This application claims priority based on Japanese Patent Application No. 2023-172354 filed on October 3, 2023, Japanese Patent Application No. 2023-172370 filed on October 3, 2023, and Japanese Patent Application No. 2024-134343 filed on August 9, 2024, the entire contents of which are incorporated herein by reference.

[0133] 3: Toner bottle, 21: Developing device, 80: Image forming device, 60: Primary transfer device, 62: Intermediate transfer body, 63: Paper feeder, 64: Secondary transfer section, 68: Fixing means, 70: Paper discharge tray, 101: Injection molding machine, 102: Preform mold, 103: Preform mold, 104: Preform, 105: Heating cylinder, 106: Preform mouth, 107: Heating furnace, 108: Blow mold, 109: Stretching rod, 110: Gas, 112: Blow molded product, 207: Extrusion screw, 301: Direct blow molding machine, 302: Direct blow mold, 303: Blow pin

Claims

1. A method for producing a blow molded product, comprising the steps of: blow molding a resin mixture containing at least wax, polyethylene or polypropylene, and a carbodiimide compound to obtain a blow molded product.

2. The method for producing a blow molded article according to claim 1, wherein the polyethylene or polypropylene is the polyethylene, and the polyethylene is at least one selected from the group consisting of high-density polyethylene, low-density polyethylene, and linear low-density polyethylene.

3. The method for producing a blow molded article according to claim 1, wherein the polyethylene or polypropylene is the polypropylene, and the polypropylene is at least one selected from the group consisting of a homopolymer, a random copolymer, and a block copolymer.

4. The method for producing a blow molded article according to any one of claims 1 to 3, wherein the wax comprises an ester wax.

5. The method for producing a blow molded article according to any one of claims 1 to 4, wherein the blow molded article is a toner bottle.

6. The method for producing a blow molded article according to any one of claims 1 to 5, wherein the blow molded article is a stretch blow molded article or a direct blow molded article.

7. The method for producing a blow molded article according to any one of claims 1 to 5, wherein the step of obtaining the blow molded article comprises the steps of: obtaining pellets of a molten mixture of the resin mixture; and performing direct blow molding using the pellets.

8. The method for producing a blow molded product according to any one of claims 1 to 5, wherein the step of obtaining the blow molded product comprises the steps of: sandwiching the molten kneaded resin mixture between metal molds and injecting gas into the mold to stretch the resin mixture.

9. The method for producing a blow molded article according to any one of claims 1 to 5, wherein the step of producing the blow molded article comprises the steps of: obtaining pellets of a molten mixture of the resin mixture; producing a preform using the pellets; and blow molding the preform.

10. The method for producing a blow molded article according to claim 9, wherein the preform has a test tube shape.

11. A method for producing a blow molded product according to claim 9 or 10, wherein the step of blow molding the preform comprises the steps of: stretching the preform in the longitudinal direction of the preform using a stretching rod; and injecting gas into the inside of the preform to stretch the preform in the circumferential direction.

12. A method for producing a blow molded article according to any one of claims 1 to 5, wherein the step of producing the blow molded article comprises the steps of: melt-kneading the wax and the polyethylene or polypropylene to form first pellets; melt-kneading the carbodiimide compound and another polyethylene or polypropylene to form second pellets; mixing the first pellets and the second pellets to obtain a pellet mixture; and blow molding the pellet mixture.

13. The method for producing a blow molded article according to claim 12, wherein the blow molding step comprises the step of injection molding the pellet mixture.

14. A method for producing a blow molded product according to any one of claims 1 to 13, wherein the content of the carbodiimide compound in the resin mixture is 400 to 1,500 parts by mass per 100 parts by mass of the wax.

15. A resin composition comprising a melt-kneaded mixture of wax, polyethylene or polypropylene, and a carbodiimide compound.

16. A pellet comprising a molten mixture of wax, polyethylene or polypropylene, and a carbodiimide compound.

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