Resin mixture, preform, biaxially oriented molded article, resin pellet, and method for manufacturing biaxially oriented molded article

Abstract

To provide a resin mixture obtained by adding carbon black to recycled resin or virgin resin, which can be used to produce biaxially oriented molded products by stretch blow molding. [Solution] A resin mixture containing a binder resin, carbon black, and a compound having a carbodiimide group, wherein the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less.

Description

Technical Field

[0001] The present disclosure relates to a resin mixture, a preform, a biaxially stretched molded article, resin pellets, and a method for producing a biaxially stretched molded article.

Background Art

[0002] In an electrophotographic image forming apparatus, since a toner bottle for supplying toner or the like needs to have strength such that it does not break even when dropped, molded articles obtained by injection stretch blow molding of polyethylene terephthalate (hereinafter also referred to as "PET"), which is a polyester resin, are often used (Patent Document 1).

[0003] These toner bottles may be colored black by adding carbon black to the PET resin in order to enhance the design property. Furthermore, there is a demand for the production of containers by injection stretch blow molding in which carbon black is added not only to toner bottles but also to enhance the light shielding property.

[0004] An injection stretch blow bottle made of PET resin is a manufacturing method in which an injection molded article having a shape like a test tube called a preform is inflated with a gas at a predetermined temperature (about 100°C). However, it is desirable that the injection molded preform has an amorphous or low crystallinity. When the crystallinity of the preform is high, the preform becomes hard, making it difficult to inflate, and the bottle may easily rupture during molding.

[0005] However, when blackened using carbon black, since carbon black as a colorant (pigment) for blackening is fine particles, it tends to become a crystal nucleus of PET and may accelerate the crystallization rate of PET (in the case of talc in Non-Patent Document 1), and the preform may crystallize and the bottle may easily rupture during blow molding.

[0006] In recent years, from an environmental protection standpoint, molded products obtained by injection stretch blow molding have been made thinner (Patent Document 2). However, the thinner these stretch blow molded products become, the more pronounced the effects of crystallization become, and even a small amount of crystallization can cause rupture. PET resin, which is blackened with carbon black, is inherently prone to crystallization, and blackening and thinning further accelerates crystallization of the preform, making injection stretch blow molding extremely difficult.

[0007] In addition, molded products are obtained by re-injecting and blow-molding used PET material (Patent Document 3). When used PET material is used, the PET material pellets obtained through material recycling may undergo hydrolysis during the recycling process, resulting in a decrease in molecular weight.

[0008] PET resins with reduced molecular weight are prone to crystallization (Non-Patent Literature 2), and during stretch blow molding, the preform is prone to crystallization and rupture. Furthermore, blackening with carbon black further accelerates the crystallization of the preform, making injection stretch blow molding of recycled PET with carbon black extremely difficult.

[0009] One way to compensate for this drawback is to replace carbon black with a black dye. However, dyes can cause the container to become transparent or fade when exposed to light. Another way to compensate for the shortcomings of recycled materials is to restore the molecular weight by repolymerizing them using solid-phase polymerization (Patent Document 4). However, solid-phase polymerization requires a lot of thermal energy and has a significant environmental impact. Thus, molding thin-walled PET blow-molded products with added carbon black is difficult, and the application of recycled materials with reduced molecular weight has been challenging. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2001-42626 [Patent Document 2] Japanese Patent Publication No. 2009-262947 [Patent Document 3] Japanese Patent Publication No. 2007-206390 [Patent Document 4] Japanese Patent Publication No. 2000-169623 [Non-patent literature]

[0011] [Non-Patent Document 1] Nikkan Kogyo Shimbun, Saturated Polyester Resin Handbook, edited by Kazuo Yuki, December 22, 1989, 1st edition, pp. 224-225, Figure 4.15. [Non-Patent Document 2] Nikkan Kogyo Shimbun, Saturated Polyester Resin Handbook, edited by Kazuo Yuki, December 22, 1989, 1st edition, pp. 224-225, Figure 4.14 [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] In the conventional example described in Patent Document 2 above, when carbon black is added to PET resin, the carbon black acts as a crystal nucleus, causing the preform to crystallize. Thin-walled blow-molded products are greatly affected by crystallization, and even a small amount of crystallization can cause the preform to burst during injection-stretch blow molding. Even if blow molding is possible, the wall thickness becomes uneven. Thus, it was not possible to obtain thin-walled blow-molded products with added carbon black.

[0013] Furthermore, in the conventional example described in Patent Document 3 above, when carbon black is added to PET resin, the molecular weight of the recycled material decreases, leading to increased crystallization of the preform and causing the preform to burst during injection stretch blow molding. Even if blow molding is possible, the wall thickness becomes uneven. Thus, it was not possible to obtain a blow-molded product using recycled material as a raw material with added carbon black.

[0014] Therefore, an object of the present disclosure is to provide a resin mixture obtained by adding carbon black to a resin of recycled material or virgin material, capable of producing a biaxially stretched molded article by a stretch blow molding method.

Means for Solving the Problems

[0015] In order to solve the above problems, the present disclosure contains a binder resin, carbon black, and a compound having a carbodiimide group, where the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the mass of the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less. Further, the present disclosure is a preform containing the above resin mixture and a polyester resin. Further, the present disclosure is a biaxially stretched molded article containing the above resin mixture and a polyester resin. Further, the present disclosure is a resin pellet containing the above resin mixture. Further, the present disclosure includes a step of producing resin pellets from the resin mixture, a step of producing a preform from the resin pellets and a polyester resin, and a step of blow molding the preform and the resin mixture contains a binder resin, carbon black, and a compound having a carbodiimide group, where the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the mass of the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less.

Advantages of the Invention

[0016] According to one aspect of the present disclosure, in the injection stretch blow molding of a thinned PET resin, a carbon black colored masterbatch capable of suppressing the crystallinity of a preform can be provided, whereby a biaxially stretched molded product of a thinned and black-colored PET resin can be obtained.

[0017] Also, by providing a carbon black colored masterbatch capable of suppressing the crystallinity of a preform in the injection stretch blow molding of a low molecular weight recycled PET resin, an injection stretch blow molded product made of a low molecular weight recycled PET resin as a raw material and colored black can be obtained.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram of an image forming apparatus according to the present disclosure. [Figure 2] It is a schematic diagram showing a method for molding a preform according to the present disclosure. [Figure 3] It is a schematic diagram showing a blow molding method according to the present disclosure. [Figure 4] It is a schematic diagram of a biaxial extruder according to the present disclosure. [Figure 5] It is a schematic diagram of one-stage method blow molding according to the present disclosure. [Figure 6] It is a schematic diagram of a blow bottle according to the present disclosure.

Embodiments for Carrying Out the Invention

[0019] In the present disclosure, the description of "XX or more and YY or less" and "XX to YY" representing a numerical range means a numerical range including the lower limit and the upper limit which are endpoints, unless otherwise specified. When the numerical range is described stepwise, any combination of the upper limit and the lower limit of each numerical range is also disclosed.

[0020] [[ID=з9]]Hereinafter, embodiments for carrying out the present disclosure will be exemplarily described in detail with reference to the drawings. However, the scope of this invention is not limited to the following embodiments. In the following description, unless otherwise specified, "%" means "mass%".

[0021] <First Embodiment> The first embodiment relates to a resin mixture. The resin mixture disclosed herein is It contains a binder resin, carbon black, and a compound having a carbodiimide group. The mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less. The following explains each item.

[0022] (Binder resin) The resin mixtures of this disclosure contain a binder resin. In this disclosure, the binder resin is preferably a thermoplastic resin, more preferably a polyester resin, and particularly preferably contains at least one selected from the group consisting of polyethylene terephthalate (PET) and polyethylene naphthalate (hereinafter also referred to as "PEN"). In this disclosure, the structure of the chemical substances can be confirmed by nuclear magnetic resonance (NMR) or gas chromatography-mass spectrometry (GC-MS).

[0023] PET is obtained by a condensation reaction or transesterification reaction between terephthalic acid or its ester-forming derivative and 1,2-ethanediol or its ester-forming derivative. It may be either copolymerized PET or homopolymer. It may also be a mixture with other resins, but it is desirable that the PET content be at least 60% by mass.

[0024] PEN is obtained by transesterifying dimethyl 2,6-naphthalenedicarboxylate with ethylene glycol to obtain the monomer bishydroxyethylene-2,6-naphthalate, followed by a polycondensation reaction. It may be a mixture with other resins, but it is desirable that the PEN content be at least 60%.

[0025] For the PET, you can use the commercially available "TRN-8550FF" manufactured by Teijin Corporation. For the PEN, you can use the commercially available "TN8065S" manufactured by Teijin Corporation.

[0026] (Carbon Black) The resin mixture of this disclosure contains carbon black. Carbon black is a pigment made from carbon. Examples of carbon black include acetylene black, furnace black, thermal black, and channel black. In this disclosure, it is preferable that the carbon black includes at least one selected from the group consisting of acetylene black, furnace black, thermal black, and channel black.

[0027] Furthermore, carbon black has the characteristic of readily acting as a crystal nucleus for crystalline resins. Alternatively, carbon black may be used as a processed pigment with surface treatment using copolymerized polyester, olefin-based resin, or metal soap. For example, the carbon black can be commercially available as "MA100" from Mitsubishi Chemical Corporation. The processed pigment can be commercially available as "Black EXC-8A1893" from Sumika Color Co., Ltd.

[0028] (Compounds containing a carbodiimide group) The resin mixture of this disclosure contains a compound having a carbodiimide group (-N=C=N-). In this disclosure, the compound having a carbodiimide group is preferably a polycarbodiimide (having multiple carbodiimide groups in the molecule). Polycarbodiimides can be produced, for example, by heating an organic isocyanate in the presence of a catalyst and performing a decarboxylation condensation reaction.

[0029] Examples of the 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), as well as alicyclic polycarbodiimides such as poly(dicyclohexylmethanecarbodiimide). These polycarbodiimides may be used individually or in any combination of two or more.

[0030] Among these polycarbodiimides, aliphatic polycarbodiimides are preferred. Aliphatic polycarbodiimides that can be used include those commercially available from Nisshinbo Chemical Co., Ltd., such as "Carbodilite HMV-15CA," "Carbodilite LA-1," and "Carbodilite HMV-5CA-LC."

[0031] In this disclosure, compounds having a carbodiimide group preferably include compounds represented by the following formula (1). [ka] (In formula (1), R is an alkylene group having 1 to 12 carbon atoms, and n is an integer between 2 and 100.)

[0032] (others) In this disclosure, with respect to 100 parts by mass of the binder resin, the mass of carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, preferably 3.0 parts by mass or more and 10.0 parts by mass or less, and more preferably 3.6 parts by mass or more and 8.3 parts by mass or less. Also in this disclosure, with respect to 100 parts by mass of the binder resin, the mass of the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less, preferably 15.0 parts by mass or more and 64.0 parts by mass or less, and more preferably 18.3 parts by mass or more and 58.3 parts by mass or less. In this way, a thin-walled, black-colored, biaxially oriented molded article of PET resin can be obtained from the resin mixture of this disclosure. In this disclosure, the structure of chemical substances and their mass ratios can be confirmed by nuclear magnetic resonance (NMR) or gas chromatography-mass spectrometry (GC-MS).

[0033] <Resin pellets> The resin pellets of this disclosure include the resin mixture of this disclosure. Resin pellets are obtained by, for example, melting the resin mixture of this disclosure in a resin extruder (single-screw, twin-screw, etc.), extruding it into a string-like shape (also called a strand), cooling it in a water tank or the like, and then cutting it into granules with a cutting device called a strand cutter.

[0034] <Preform> The preform of this disclosure comprises the resin mixture of this disclosure and a polyester resin. The preform is an intermediate product manufactured for biaxial stretching from the resin mixture of this disclosure or resin pellets of this disclosure, and is, for example, in the shape of a test tube. The preform can be placed in a mold and blown while heated to expand the preform in the mold and produce a biaxially stretched molded product.

[0035] <Biaxially stretched molded product> The biaxially oriented molded articles of this disclosure include the resin mixture of this disclosure and a polyester resin. The biaxially oriented molded articles of this disclosure are produced by blow molding a gas into the preform of this disclosure while it is at a predetermined temperature (for example, around 100°C for PET resin), which increases the overall length and diameter of the preform. There are two types of uniaxial stretching: one in which the overall length is increased, and another in which the diameter is increased. A molded article that exhibits both of these uniaxial stretching processes is called a biaxially oriented molded article. Typical biaxially oriented molded articles include PET bottles for beverages, PET bottles for soy sauce and cosmetics, and PET bottles for various containers such as toner containers for photocopiers. This disclosure can be used for these applications.

[0036] <Toner Bottle> Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram illustrating the configuration of a four-color image forming apparatus using an electrophotographic method, where 80 is the main body of the image forming apparatus. This 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.

[0037] In this image forming apparatus 80, image formation is performed as follows. First, based on the print data, the image forming apparatus 80 uses an exposure unit 50 (50y, 50m, 50c, 50bk) to form an electrostatic latent image on the photosensitive drum 17 (17y, 17m, 17c, 17bk). Then, in this image forming apparatus 80, the formed electrostatic latent image is developed using a developing unit 21 (21Y, 21M, 21c, 21bk) to form a toner image.

[0038] In this image forming apparatus 80, 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 by a secondary transfer unit 64 (64a, 64b). Next, in this image forming apparatus 80, the toner image transferred onto the sheet material S is fixed to the sheet material S by a fixing means 68, and then discharged onto a paper output tray 70.

[0039] Furthermore, in this image forming apparatus 80, a toner image is formed in the developing apparatus 21, and a detachable toner bottle 3 (3Y, 3M, 3C, 3Bk) is used to supply toner to the developing apparatus 21. The toner bottle of this disclosure is a toner bottle 3 used in this manner. For reference, an example of the shape of the toner bottle 3 is shown in Figure 6.

[0040] <Second Embodiment> The second embodiment relates to a method for manufacturing a biaxially stretched molded product. The method for manufacturing a biaxially stretched molded article according to this disclosure is: The process of producing resin pellets from a resin mixture, A process for producing a preform from the resin pellets and polyester resin, The process of blow-molding the preform and Includes, The resin mixture contains a binder resin, carbon black, and a compound having a carbodiimide group. The mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less. Some items described in the first embodiment overlap with those described in the second embodiment, so their explanations may be omitted.

[0041] Next, one embodiment of the method for producing the resin mixture according to this disclosure will be described. (Process for producing resin pellets) The method for manufacturing a biaxially stretched molded article according to this disclosure includes a step of producing resin pellets from a resin mixture. That is, a resin mixture (hereinafter sometimes referred to as "masterbatch") is produced by melt-kneading a binder resin, carbon black, and carbodiimide, followed by extrusion to produce pellets. The means of melt-kneading are not particularly limited, and known means such as a twin-screw extruder can be used as shown in Figure 4. For example, a PCM-46 (manufactured by Ikegai Co., Ltd.) can be used as a twin-screw extruder. The extruder 201 has a screw inside, and by rotating the screw, the resin fed into the hopper 202 can be melt-kneaded.

[0042] The binder resin 203, carbon black 204, and carbodiimide 205 are supplied in quantitative quantities to the hopper 202. The melt-mixing temperature is not particularly limited, but when the binder resin is a polyester resin, it is, for example, 200-300°C, preferably 240-280°C. The resin, extruded into a string shape, is cooled by passing it through a water tank 207 and then cut by a cutting machine 206 to obtain a pellet-shaped resin mixture 208.

[0043] The carbon black in the resin mixture has the function of coloring the toner bottle black. To achieve black coloring, if the binder resin is 100 parts by mass, 1.0 to 20.0 parts by mass of carbon black must be mixed in.

[0044] Polycarbodiimide, a resin mixture, has the property of reacting with polyester resin, which is the material for toner bottles. The carbodiimide groups of polycarbodiimide crosslink with the carboxyl groups at the ends of the polyester resin. Because polycarbodiimide has multiple carbodiimide groups, it can bond with multiple ends of the polyester resin.

[0045] Normally, carbon black acts as a nucleus for polyester resin crystallization and promotes crystallization, but polycarbodiimide can increase the molecular weight, thereby slowing down the acceleration of polyester resin crystallization. To obtain the effect of delaying the crystallization rate of polyester resin, if the binder resin in the resin mixture is 100 parts by mass, it is necessary to add 3.0 to 64.0 parts by mass of carbodiimide.

[0046] The resin mixture relating to this disclosure is used by mixing it with the toner bottle material during biaxial stretch blow molding, as described below. While it's possible to directly add carbon black and polycarbodiimide to the polyester resin of the toner bottle without pre-mixing them into a resin mixture, forming the resin mixture with carbon black and polycarbodiimide using a binder resin suppresses the crystallization of carbon black. This is because when forming a resin mixture, a small amount of polycarbodiimide crosslinks with the binder resin within the mixture, increasing the molecular weight of the binder resin. Within the resin mixture, there is a large amount of binder resin with a high molecular weight surrounding the carbon black. When the resin mixture is added to the toner bottle material, the resin mixture is dispersed, but there is a large amount of resin with a high molecular weight surrounding the carbon black, creating an environment that is less conducive to crystallization with the carbon black as a nucleus.

[0047] On the other hand, there is also a method of directly adding carbon black and polycarbodiimide to the polyester resin of the toner bottle without pre-mixing them into a resin mixture. In this case, the carbon black comes into contact with the polyester resin that is not crosslinked with polycarbodiimide, and crystallization of the polyester resin may proceed with the carbon black acting as a nucleus. The resin mixture relating to this disclosure is used by mixing it with the toner bottle material during biaxial stretch blow molding, as described below.

[0048] (Preform manufacturing process) The method for manufacturing a biaxially oriented molded article according to this disclosure includes a step of preparing a preform from resin pellets and polyester resin. One embodiment of a method for producing a preform by biaxially oriented blow molding using the resin mixture according to this disclosure is described below.

[0049] As shown in Figure 2, a preform 104 having a test tube-like shape is formed by injection molding. Specifically, a material containing a pre-mixed toner bottle material and masterbatch is fed into the injection molding machine 101, a heating cylinder 105 heats and melts the material, and a screw 106 injects the molten material into preform molds 102 and 103 to form the preform 104.

[0050] Toner bottles are made of polyester resin such as PET or PEN, and it is preferable that the binder resin of the masterbatch matches the material of the toner bottle. In the manufacturing method of a biaxially oriented molded article according to this disclosure, in the step of making a preform, the amount of resin pellets is preferably 0.8 parts by mass or more and 2.0 parts by mass or less, more preferably 1.1 parts by mass or more and 1.7 parts by mass or less, and particularly preferably 1.4 parts by mass, relative to 100 parts by mass of polyester resin. In this way, the manufacturing method of a biaxially oriented molded article according to this disclosure makes it even easier to manufacture a biaxially oriented molded article by stretch blow molding.

[0051] The toner bottle material and masterbatch are stirred with screw 106 while in a molten state. The carbon black in the masterbatch is then dispersed in the toner bottle material, forming a black preform 104. Additionally, the polycarbodiimide in the masterbatch reacts with the polyester resin in the toner bottle material. Specifically, the carbodiimide groups bond to the carboxyl groups at the ends of the polyester resin. Furthermore, because the polycarbodiimide has multiple carbodiimide groups within its molecule, multiple polyester resins are bonded via the polycarbodiimide.

[0052] Normally, crystallization progresses due to the heat contained in the preform 104 during the cooling process immediately after injection is complete. However, polyester resins whose molecular weight has increased due to bonding with polycarbodiimide have a slower crystallization rate, which can suppress the crystallization of the preform 104.

[0053] (The process of blow-molding the preform) The method for manufacturing a biaxially oriented molded product according to this disclosure includes a step of blow molding a preform. As shown in Figure 3, biaxial stretch blow molding is performed. First, the preform 104 is placed in a heating furnace 107 and heated to a temperature at which it can be stretched. Here, too, the reaction between the polyester resin and polycarbodiimide increases the molecular weight, which slows down the crystallization rate, and crystallization can be suppressed if the heating time is within 3 minutes. After heating, the heated preform 104 is removed from the heating furnace 107 and placed in the mouth of a blow mold 108, which has a cavity formed inside by combining the left mold 108-1 and the right mold 108-2. Furthermore, it is preferable to place the heated preform into the mouth of the blow mold 108 within a short time (for example, within 10 seconds) so that the temperature of the preform does not drop before the start of the biaxial stretching process.

[0054] A heated preform 104 placed inside a blow mold 108 is stretched longitudinally using a stretching rod 109. This stretching is called primary stretching. At this time, it is preferable to introduce gas so that the preform 104 does not come into contact with the stretching rod 109, and the pressure of this gas is called the primary blow pressure.

[0055] After the primary stretching, gas 110 is introduced through the preform opening 113 to expand the preform laterally (circumferentially). This is called secondary stretching. The gas pressure at this time is called the secondary blow pressure. Examples of gases to be injected include air, nitrogen, carbon dioxide, and argon.

[0056] Through these primary and secondary stretching processes, the preform 104 expands in the directions indicated by the arrows 301, adhering tightly to the inner wall of the blow mold 108, and then cools and solidifies in that state. Next, the blow-molded product 112 is removed from the blow mold 108 by separating the left mold 108-1 and the right mold 108-2. Because this blow-molded product 112 is stretched in both the longitudinal and transverse directions, it becomes a molded product with high strength.

[0057] In the injection stretch blow molding process, it is crucial that the preform is in an amorphous state (non-crystalline). When the blow molding temperature is reached while the preform is in an amorphous state, it is soft and easily deformable. By blow molding, or biaxial stretch molding, the PET crystallizes in the direction of stretching, making it possible to form a high-strength bottle.

[0058] There are two methods for injection stretch blow molding: the one-stage method and the two-stage method. The one-stage method uses the residual heat of the preform immediately after removal from the mold to perform stretch blow molding, either directly or with controlled temperature. The two-stage method involves cooling the preform to room temperature, then controlling the temperature again before stretch blow molding.

[0059] In the one-stage method, as shown in Figure 5, a preform 104 is injected from an injection molding machine 101. To prevent the preform 104 from falling below the glass transition temperature of PET, cooling is completed in a short time of 10 seconds or less during injection molding. Then, it is immediately heated to a blow molding temperature (for example, 80°C to 120°C) and blow molded to obtain a blow-molded product 112 (blow-molded bottle). An integrated injection molding apparatus and blow molding apparatus are used.

[0060] The two-stage method involves injection molding a preform, then cooling and removing the preform below the glass transition temperature of PET, and finally heating it to the blow molding temperature (for example, 80°C to 120°C) in a separate blow molding apparatus to perform blow molding. This method utilizes a system where the injection molding apparatus and the blow molding apparatus are separate.

[0061] The one-stage method is preferable because it does not require the energy of reheating, unlike the two-stage method, since the preform is not cooled below the glass transition temperature. However, because the PET is held at its crystallization temperature for a longer period after injection molding, isothermal crystallization of PET proceeds more easily than in the two-stage method. This crystallization temperature of PET is approximately 130°C to 200°C. Therefore, the resin mixture disclosed herein has the effect of delaying crystallization in both the one-stage and two-stage methods, but the effect is particularly high in the one-stage method.

[0062] (others) The method for producing a biaxially stretched molded article according to the present disclosure is characterized in that the resin mixture contains a binder resin, carbon black, and a compound having a carbodiimide group, wherein the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, preferably 3.0 parts by mass or more and 10.0 parts by mass or less, more preferably 3.6 parts by mass or more and 8.3 parts by mass or less, and the mass of the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less, preferably 15.0 parts by mass or more and 64.0 parts by mass or less, more preferably 18.3 parts by mass or more and 58.3 parts by mass or less. Since these descriptions overlap with the description of the first embodiment, the explanation is omitted.

[0063] [Example 1] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to these examples. In the following examples, unless otherwise specified, "%" means "mass%".

[0064] <Molding of resin mixtures> The resin mixture was molded using a twin-screw extruder (PCM-46, manufactured by Ikegai Co., Ltd.). PET, carbon black, and polycarbodiimide were uniformly and precisely supplied while being melt-kneaded. During this process, the mixing ratios of PET, carbon black, and polycarbodiimide were varied as shown in Table 1. The material was melt-kneaded at a melt-kneading temperature of 260°C, a screw rotation speed of 250 rpm, vent degassing at -0.05 MPa, and a discharge rate of 80 kg / h, and then pelletized. The carbon black and polycarbodiimide used here were in powder form. The pelletized resin mixture was subjected to a heat treatment at a temperature of 180°C for 4 hours to produce a material that can be used in injection stretch blow molding. These materials were designated MB(1-1), MB(1-2), and MB(1-3).

[0065] [Table 1]

[0066] <Molding blow-molded bottles> The PET material for the toner bottle and the resin pellets MB(1-1), MB(1-2), and MB(1-3) are pre-mixed before being fed into a one-step stretch blow molding machine (ASB-70DPH, manufactured by Nissei ASB Machinery Co., Ltd.). This machine uses a one-stage injection stretch blow molding method. The mixing ratios of the toner bottle material and each of MB(1-1), MB(1-2), and MB(1-3) are shown in Tables 2-1, 2-2, and 2-3, respectively. Note that the materials listed in Tables 2-1 to 2-3 are used in a dry state.

[0067] [Table 2-1]

[0068] [Table 2-2]

[0069] [Table 2-3]

[0070] The above-described one-step stretch blow molding machine can continuously perform the steps of obtaining a preform by injection molding and obtaining a bottle-shaped molded product by biaxial stretch blow molding of the preform. The screw diameter of the injection molding machine in the molding machine in question was 54 mm.

[0071] First, a mold was prepared for molding preforms with an outer diameter of 30 mm, a wall thickness of 3.7 mm, and a length of 220 mm. Then, the preforms were molded under the following molding conditions. Screw diameter: 54mm • Screw position before filling the cavity with resin mixture: 95mm ·Injection speed Until the propeller is advanced 5mm: 50% of maximum speed Until the propeller is advanced another 20mm: 30% of maximum speed Until the propeller is advanced another 35mm: 25% of maximum speed PV switching position: 35mm · Injection pressure • PV switchover time: 12.0 MPa • After switching to PV: 4.5 MPa (holding pressure) • Holding pressure time after PV switchover ·4.57 seconds ·Heating tube temperature: 280℃ ·Cooling time: 8.0 seconds • Mold temperature: 18℃

[0072] In the injection molding machine, the materials listed in Tables 2-1 to 2-3 are melted and mixed, resulting in a black-colored preform due to the carbon black contained in MB(1-1), MB(1-2), and MB(1-3). MB(1-2) has a lower carbon black content, resulting in a lighter color compared to MB(1-1) and MB(1-3). This is not a problem from an aesthetic standpoint.

[0073] Furthermore, the polycarbodiimides contained in MB(1-1), MB(1-2), and MB(1-3) crosslink the PET, increasing the molecular weight of the PET. This delays crystallization, allowing for the molding of soft, non-crystallized preforms. Because MB(1-3) has a higher proportion of polycarbodiimides, it can delay crystallization even more effectively compared to MB(1-1) and MB(1-2).

[0074] The preform was demolded from the preform molding die and transported to the heating station of the one-step stretch blow molding machine. The heating conditions were as follows: • Preform temperature 180°C, 10% of the preform's total length from the top of the preform. 25% of the preform's total length from the top, at 200°C. 50% of the preform's total length from the top, 200°C 180°C, 75% of the preform's total length, from the top of the preform.

[0075] Next, the preform, which had been adjusted to the above temperature, was placed inside a mold shaped like a toner bottle, and the toner bottle was formed by biaxial stretch blow molding. The mold temperature was adjusted to 18°C. The surface temperature of the preform immediately before blow molding was 100°C.

[0076] The specific blow molding process is described below. A stretching rod was inserted into the preform through the opening and advanced until it contacted the top of the preform. Next, the stretching rod was further advanced with an air pressure of 1.2 MPa driving it. At this time, 0.5 seconds after the stretching rod had been further advanced, primary air was injected into the preform through the opening. The pressure of the primary air was set to 1.0 MPa.

[0077] Next, secondary air was introduced 0.15 seconds after the primary air injection. The pressure of the secondary air was set to 2.9 MPa. Then, air was injected into the preform for 7.0 seconds from the start of the primary air introduction. Next, the pressure inside the preform was returned to atmospheric pressure over 2.5 seconds. In this way, a thin-walled, black toner bottle with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm was obtained.

[0078] [Example 2] <Molding of resin mixtures> MB(1-1) is molded in the same manner as in Example 1.

[0079] <Molding blow-molded bottles> Recycled materials are used as the material for the toner bottles. The recycled material is made by collecting and crushing used PET beverage bottles. Commercially available "HPR" manufactured by Pantec was used. Because the crushed PET has a low bulk density and will not feed into the screw of the injection molding machine in a biaxial stretch blow molding machine, it is melted and kneaded in an extruder to increase its bulk density.

[0080] The mixture is melt-kneaded using a twin-screw extruder (PCM-46, manufactured by Ikegai Co., Ltd.) according to the formulation in Table 3. The extrusion conditions are as follows: Temperature: 260℃ Screw rotation speed: 200 rpm Discharge amount: 50kg / h

[0081] [Table 3]

[0082] The material, which was melt-kneaded and pelletized under these conditions, was heat-treated at 180°C for 4 hours to form pellets for injection molding. This material was designated PCR(2-1). The IV value of PCR(2-1) was 0.64 dL / g.

[0083] The recycled PET PCR(2-1) and MB(1-1) are pre-mixed and then fed into a one-step stretch blow molding machine (ASB-70DPH, manufactured by Nissei ASB Machinery Co., Ltd.). The mixing ratio of PCR(2-1) and MB(1-1) is shown in Table 4. Note that the materials listed in Table 4 should be fed into the molding machine in a dry state.

[0084] [Table 4]

[0085] The preform molding for one-step stretch blow molding is performed in the same manner as in Example 1. PCR(2-1) and MB(1-1) are melt-mixed by the screw of an injection molding machine. As a result, a black colored preform is obtained due to the carbon black contained in MB(1-1). Furthermore, the polycarbodiimide contained in MB(1-1) crosslinks with the PET in PCR(2-1), increasing the molecular weight of the PET. This increased molecular weight of PCR(2-1) slows down the crystallization rate even when carbon black, which acts as a crystal nucleation site, is present, resulting in a soft preform at blow molding temperatures. By blow molding this preform in the same manner as in Example 1, a black toner bottle made from recycled material with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm can be obtained.

[0086] [Example 3] <Molding of resin mixtures> The resin mixture was molded using the same twin-screw extruder and molding conditions as in Example 1. PET, carbon black, and polycarbodiimide were uniformly and quantitatively supplied in the mixing ratios shown in Table 5 and melt-kneaded, but powdered processed pigment was used for the carbon black. The pelletized resin mixture was heat-treated by maintaining a temperature of 180°C for 4 hours to obtain a material that could be used in injection stretch blow molding. This material was designated MB(3-1).

[0087] [Table 5]

[0088] <Molding blow-molded bottles> The PET and MB(3-1) materials for the toner bottle are pre-mixed and then fed into a one-step stretch blow molding machine (ASB-70DPH, manufactured by Nissei ASB Machinery Co., Ltd.). The mixing ratio of the toner bottle materials and MB(3-1) is shown in Table 6. Note that the materials listed in Table 6 should be used in a dry state.

[0089] [Table 6]

[0090] The PET and MB(3-1) are melted and kneaded in the screw of the injection molding machine. This results in a preform colored black by the carbon black contained in MB(3-1). The polycarbodiimide contained in MB(3-1) crosslinks with the PET, increasing the molecular weight of the PET. Furthermore, the carbon black used here is a processed pigment with a resin coating on its surface. Therefore, there is little direct contact between the carbon black and the PET, and it ceases to function as a crystal nucleus for the PET.

[0091] As described above, by increasing the molecular weight of PET and using coated carbon black, the crystallization rate of the preform can be slowed compared to Examples 1 and 2. The preform molded using this method remains soft even at blow molding temperatures. By blow molding this preform in the same manner as in Example 1, a black toner bottle made from recycled material with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm can be obtained.

[0092] [Example 4] <Molding of resin mixtures> In previous examples, the binder resin and the material for the biaxially oriented molded product were shown to be PET, but the same effect can be obtained with PEN. The resin mixture was molded using the same biaxial extruder and molding conditions as in Example 1. Using PEN as the binder resin, carbon black and polycarbodiimide were uniformly and quantitatively supplied in the mixing ratios shown in Table 7 while melt-kneading. The pelletized resin mixture was heat-treated by maintaining a temperature of 180°C for 4 hours to obtain a material that can be used in injection stretch blow molding. This material was designated MB(4-1).

[0093] [Table 7]

[0094] <Molding blow-molded bottles> PEN and MB(4-1) are pre-mixed and then fed into a one-step stretch blow molding machine (ASB-70DPH, manufactured by Nissei ASB Machinery Co., Ltd.). The mixing ratio of PEN and MB(4-1) is shown in Table 8. Note that the materials listed in Table 8 should be used in a dry state.

[0095] [Table 8]

[0096] The preform molding for one-step stretch blow molding is performed in the same manner as in Example 1. In the injection molding machine's screw, PEN and MB(4-1) are melted and kneaded together. This results in a preform colored black by the carbon black contained in MB(4-1). Furthermore, the polycarbodiimide contained in MB(4-1) crosslinks with PEN, increasing the molecular weight of PEN. This increased molecular weight of PEN slows down the crystallization rate, even when carbon black, which acts as a crystal nucleus, is present, resulting in a soft preform at blow molding temperatures.

[0097] The preform was demolded from the preform molding die and transported to the heating station of the one-step stretch blow molding machine. The heating conditions were as follows: • Preform temperature 10% of the preform's total length from the top, 270°C 300°C, 25% of the preform's total length from the top of the preform. 50% of the preform's total length from the top, 300°C 75% of the preform's total length, from the top of the preform, at 270°C.

[0098] Next, the preform, which had been adjusted to the above temperature, was placed inside a mold shaped like a toner bottle, and the toner bottle was formed by biaxial stretch blow molding. The mold temperature was adjusted to 18°C. The surface temperature of the preform immediately before blow molding was 150°C.

[0099] The specific blow molding process is described below. A stretching rod was inserted into the preform through the opening and advanced until it contacted the top of the preform. Next, the stretching rod was further advanced with an air pressure of 1.2 MPa driving it. At this time, 0.5 seconds after the stretching rod had been further advanced, primary air was injected into the preform through the opening. The pressure of the primary air was set to 1.0 MPa.

[0100] Next, secondary air was introduced 0.15 seconds after the primary air injection. The pressure of the secondary air was set to 2.9 MPa. Then, air was injected into the preform for 7.0 seconds from the start of the primary air introduction. Next, the pressure inside the preform was returned to atmospheric pressure over 2.5 seconds. In this way, a black, biaxially oriented molded product was obtained that was thin-walled, with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm, and made of PEN, which has higher heat resistance, gas barrier properties, and mechanical strength than PET.

[0101] This embodiment includes the following configurations and methods. (Composition 1) It contains a binder resin, carbon black, and a compound having a carbodiimide group. A resin mixture wherein the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less. (Configuration 2) The binder resin is a thermoplastic resin, as described in configuration 1. (Composition 3) The resin mixture according to configuration 1 or 2, wherein the binder resin is a polyester resin. (Composition 4) The binder resin is a resin mixture according to any one of configurations 1 to 3, wherein the binder resin comprises at least one selected from the group consisting of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). (Composition 5) The resin mixture according to any one of configurations 1 to 4, wherein the carbon black comprises at least one selected from the group consisting of acetylene black, furnace black, thermal black, and channel black. (Composition 6) The resin mixture according to any one of configurations 1 to 5, wherein the compound having the carbodiimide group is polycarbodiimide. (Composition 7) The compound having the carbodiimide group is a resin mixture according to any one of configurations 1 to 6, comprising a compound represented by the following formula (1). [ka] (In formula (1), R is an alkylene group having 1 to 12 carbon atoms, and n is an integer between 2 and 100.) (Composition 8) A preform comprising a resin mixture described in any one of Compositions 1 to 7 and a polyester resin. (Composition 9) A biaxially oriented molded article comprising a resin mixture described in any one of the components 1 to 7 and a polyester resin. (Composition 10) A resin pellet comprising the resin mixture described in any one of the components 1 to 7. (Method 1) The process of producing resin pellets from a resin mixture, A process for producing a preform from the resin pellets and polyester resin, The process of blow-molding the preform and Includes, The resin mixture contains a binder resin, carbon black, and a compound having a carbodiimide group. A method for producing a biaxially oriented molded article, wherein the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less. (Method 2) A method for producing a biaxially oriented molded article according to Method 1, wherein in the step of producing the preform, the amount of resin pellets is 0.8 parts by mass or more and 2.0 parts by mass or less, relative to 100 parts by mass of polyester resin. [Industrial applicability]

[0102] The technologies described herein are technologies that can contribute to the realization of a sustainable society, such as a decarbonized / circular economy. [Explanation of Symbols]

[0103] 3 Toner Bottles 80 Image forming apparatus 50 Exposure apparatus 17 Photosensitive drum 21 Developing device 60 Primary Transfer Device 62 Intermediate Transfer Form 63 Paper feed device 64 Secondary transfer section 70 Paper output tray 101 Injection molding machine 102 Preform mold 103 Preform mold 104 Preform 105 Heating cylinder 106 Screw 107 Heating Furnace 108 Blow mold 109 Stretching rod 110 Gas 112 Blow molded product 113 Preform opening 201 Extruder 202 Hopper 203 Binder resin 204 Carbon Black 205 Carbodiimide 206 Cutting machine 207 Aquarium 208 Resin mixture 301 Direction of expansion of the preform

Claims

1. It contains a binder resin, carbon black, and a compound having a carbodiimide group. A resin mixture wherein the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less.

2. The resin mixture according to claim 1, wherein the binder resin is a thermoplastic resin.

3. The resin mixture according to claim 1, wherein the binder resin is a polyester resin.

4. The resin mixture according to claim 1, wherein the binder resin comprises at least one selected from the group consisting of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).

5. The resin mixture according to claim 1, wherein the carbon black comprises at least one selected from the group consisting of acetylene black, furnace black, thermal black, and channel black.

6. The resin mixture according to claim 1, wherein the compound having the carbodiimide group is polycarbodiimide.

7. The resin mixture according to claim 1, wherein the compound having the carbodiimide group includes a compound represented by the following formula (1). 【Chemistry 1】 (In formula (1), R is an alkylene group having 1 to 12 carbon atoms, and n is an integer between 2 and 100.)

8. A preform comprising a resin mixture according to any one of claims 1 to 7 and a polyester resin.

9. A biaxially oriented molded article comprising a resin mixture according to any one of claims 1 to 7 and a polyester resin.

10. A resin pellet comprising the resin mixture according to any one of claims 1 to 7.

11. The process of producing resin pellets from a resin mixture, A process for producing a preform from the resin pellets and polyester resin, The process of blow-molding the preform and Includes, The resin mixture contains a binder resin, carbon black, and a compound having a carbodiimide group. A method for producing a biaxially oriented molded article, wherein the mass of the binder resin is 100 parts by mass, the mass of the carbon black is 1.0 part by mass or more and 20.0 parts by mass or less, and the compound having a carbodiimide group is 3.0 parts by mass or more and 64.0 parts by mass or less.

12. The method for manufacturing a biaxially oriented molded article according to claim 11, wherein in the step of manufacturing the preform, the amount of the polyester resin is 100 parts by mass, and the amount of the resin pellets is 0.8 parts by mass or more and 2.0 parts by mass or less.

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