Resin mixture, preform, biaxially-stretched molded article, resin pellet, and method for producing biaxially-stretched molded article

Abstract

The present invention relates to a resin mixture, a preform, a biaxially stretch-molded article, a resin pellet, and a method for producing a biaxially stretch-molded article. A resin mixture includes a resin of a recycled material or a resin of a virgin material and carbon black added to the resin, and a biaxially stretch-molded article can be produced by a stretch blow molding method. The resin mixture includes a binder resin, carbon black, and a compound having a carbodiimide group. The mass of the carbon black is 1.0 mass part or more and 20.0 mass parts or less, and the mass of the compound having a carbodiimide group is 3.0 mass parts or more and 64.0 mass parts or less, based on 100 mass parts of the binder resin.

Description

Technical Field

[0001] This disclosure relates to resin mixtures, preforms, biaxially stretched molded articles, resin granules, and methods for producing biaxially stretched molded articles. Background Technology

[0002] In electrophotographic image forming equipment, the toner bottle used to supply toners, etc., needs to have the strength to not break even when dropped. Therefore, a large number of molded articles obtained by injection stretch blow molding of polyethylene terephthalate (hereinafter also referred to as "PET"), which is a polyester resin, are used (Japanese Patent Application Laid-Open No. 2001-42626).

[0003] To enhance design flexibility, these toner bottles are sometimes colored black by adding carbon black to the PET resin. Furthermore, to enhance opacity (not limited to toner bottles), containers containing carbon black are required to be manufactured using injection stretch blow molding.

[0004] Injection stretch blow molding bottles made from PET resin are produced by inflating an injection-molded article (called a preform) with a test tube shape using gas at a predetermined temperature (approximately 100°C). Ideally, the injection-molded preform is amorphous or has low crystallinity. If the preform has high crystallinity, it becomes hard and difficult to expand, making the bottle more likely to burst during molding.

[0005] However, when coloring toner bottles black using carbon black, the carbon black is likely to act as a crystal nucleus. This is because the carbon black used as a colorant (pigment) to color the bottles black is fine-grained, and the crystallization rate of PET sometimes increases (in The Nikkan Kogyo Shimbun, Ltd., Saturated Polyester Resin Handbook (edited by Kazuo Yuki, December 22, 1989, first edition, pp. 224-225)). Figure 4 In the case of talc described in .15), the preform crystallizes, and the bottle may sometimes burst during blow molding.

[0006] Furthermore, in recent years, from an environmental protection perspective, efforts have been made to reduce the thickness of molded articles obtained through injection stretch blow molding (Japanese Patent Application Laid-Open No. 2009-262947). Regarding these thinned stretch blow molded articles, as the article becomes thinner, the effect of crystallization becomes significant, and even in the case of a small amount of crystallization, cracking can occur. The PET resin, colored black with carbon black, is itself prone to crystallization, and due to the black coloring and thinning, crystallization of the preform is likely to proceed further, making injection stretch blow molding extremely difficult.

[0007] Furthermore, molded articles were obtained from used PET material by injection stretch blow molding (Japanese Patent Application Publication No. 2007-206390). When used PET material is used, that is, when granules of PET material obtained through material recycling are used, the PET material is hydrolyzed during the recycling process, and the molecular weight sometimes decreases.

[0008] PET resins with lower molecular weights tend to crystallize (The Nikkan Kogyo Shimbun, Ltd., Saturated Polyester Resin Handbook, edited by Kazuo Yuki, December 22, 1989, 1st edition, pp. 224-225). Figure 4 .14), and the preform is prone to cracking due to crystallization during stretch blow molding. If the preform is colored black with carbon black, the crystallization of the preform is likely to proceed further, so it is extremely difficult to use recycled PET that has already been colored black with carbon black for injection stretch blow molding.

[0009] As a way to compensate for these drawbacks, carbon black is sometimes replaced with black dye. However, when exposed to light, the dye can sometimes cause the container to become transparent or fade. As a way to compensate for the drawbacks of recycled materials, repolymerization is carried out through solid-state polymerization, thereby restoring the molecular weight (Japanese Patent Application Laid-Open No. 2000-169623). However, solid-state polymerization requires a large amount of thermal energy and has a serious environmental impact.

[0010] As mentioned above, molding thin PET blow-molded articles with added carbon black is difficult, and applying recycled materials with reduced molecular weight is also challenging.

[0011] In the conventional embodiment described in Japanese Patent Application Publication No. 2009-262947, if carbon black is added to the PET resin, the carbon black becomes a nucleus and causes the preform to crystallize. Thin blow-molded articles are greatly affected by crystallization, and even in the case of trace amounts of crystallization, the preform cracks during injection stretch blow molding. Even when blow molding is possible, thickness non-uniformity increases. Therefore, it is impossible to obtain thin blow-molded articles containing added carbon black.

[0012] In the conventional embodiments described in Japanese Patent Application Publication No. 2007-206390, if carbon black is added to PET resin, crystallization of the preform occurs because the molecular weight of the recycled material decreases, and the preform cracks during injection stretch blow molding. Even when blow molding is possible, thickness inhomogeneity increases. Therefore, by using recycled material as a raw material, it is impossible to obtain blow-molded articles containing added carbon black. Summary of the Invention

[0013] Therefore, this disclosure relates to providing a resin mixture in which carbon black is added to a resin of recycled material or a resin of virgin material, and the resin mixture can be used to prepare biaxially stretched articles by stretch blow molding.

[0014] To address the aforementioned drawbacks, this disclosure provides a resin mixture comprising an adhesive resin, carbon black, and a compound having a carbodiimide group, wherein, based on 100 parts by mass of the adhesive resin, the carbon black comprises 1.0 or more parts by mass and 20.0 or less parts by mass, and the compound having a carbodiimide group comprises 3.0 or more parts by mass and 64.0 or less parts by mass.

[0015] Furthermore, this disclosure pertains to preforms comprising the aforementioned resin mixture and polyester resin.

[0016] Furthermore, this disclosure pertains to biaxially stretched molded articles comprising the aforementioned resin mixture and polyester resin.

[0017] Furthermore, this disclosure pertains to resin granules comprising the aforementioned resin mixture.

[0018] Furthermore, this disclosure pertains to a method for producing biaxially stretched molded articles, comprising preparing resin granules from a resin mixture, preparing a preform from the resin granules and polyester resin, and blow molding the preform, wherein the resin mixture comprises a binder resin, carbon black, and a compound having carbodiimide groups, and based on 100 parts by mass of the binder resin, the carbon black comprises 1.0 or more and 20.0 or less by mass, and the compound having carbodiimide groups comprises 3.0 or more and 64.0 or less by mass.

[0019] Referring to the accompanying drawings, the features of this disclosure will become apparent from the following description of embodiments. The following description of embodiments is illustrated by way of example. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an image forming apparatus according to the present disclosure.

[0021] Figure 2 This is a schematic diagram illustrating a method for forming a preform according to the present disclosure.

[0022] Figure 3 This is a schematic diagram illustrating a blow molding method according to the present disclosure.

[0023] Figure 4 This is a schematic diagram of a twin-screw extruder based on this disclosure.

[0024] Figure 5 This is a schematic diagram of blow molding according to the one-stage method of this disclosure.

[0025] Figure 6 This is a schematic diagram of a blow-molded bottle according to this disclosure. Detailed Implementation

[0026] In this disclosure, unless otherwise stated, the descriptions of numerical ranges “above XX and below YY” and “XX to (~)YY” each refer to a numerical range including a lower limit and an upper limit as endpoints, and when the numerical range is described in segments, optional combinations of the upper and lower limits in each numerical range are also disclosed.

[0027] In the following, embodiments for carrying out this disclosure will be described in detail illustratively with reference to the accompanying drawings. However, the scope is not limited to the following embodiments. In the following description, unless otherwise stated, "%" means "mass %".

[0028] <First Implementation Plan>

[0029] The first implementation plan pertains to resin mixtures.

[0030] The resin mixture disclosed herein comprises an adhesive resin, carbon black, and a compound having a carbodiimide group, wherein, based on 100 parts by mass of the adhesive resin, the carbon black comprises 1.0 or more parts by mass and 20.0 or less parts by mass, and the compound having a carbodiimide group comprises 3.0 or more parts by mass and 64.0 or less parts by mass.

[0031] Each item will be described below.

[0032] (Adhesive resin)

[0033] The resin mixtures disclosed herein comprise binder resins. In this disclosure, the binder resin is preferably a thermoplastic resin, more preferably a polyester resin, and particularly preferably comprises 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 substance can be confirmed by nuclear magnetic resonance (NMR) or gas chromatography-mass spectrometry (GC-MS).

[0034] PET is obtained by condensation or transesterification of terephthalic acid or its ester-forming derivatives with 1,2-ethylene glycol or its ester-forming derivatives. PET can be either copolymer PET or homopolymer PET. PET can be a mixture with other resins, but the PET content is ideally at least 60% by mass.

[0035] PEN is obtained by transesterifying dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol to obtain the monomer dihydroxyethylidene-2,6-naphthalenedicarboxylate, followed by polycondensation of the monomer. PEN can be a mixture with other resins, but the PEN content is ideally at least 60% by mass.

[0036] As PET, commercially available PET manufactured by Teijin Limited as "TRN-8550FF" can be used. As PEN, commercially available PEN manufactured by Teijin Limited as "TN8065S" can be used.

[0037] (Carbon black)

[0038] The resin mixture disclosed herein contains carbon black. Carbon black is a pigment that uses carbon as a raw material. Examples of carbon black include acetylene black, furnace black, thermal cracking carbon black, and channel black.

[0039] In this disclosure, the carbon black preferably comprises at least one selected from the group consisting of acetylene black, furnace black, thermal cracking carbon black and channel black.

[0040] Carbon black has the following characteristics: it is highly likely to become a nucleus for crystalline resins. Carbon black can be a processed pigment obtained by surface treatment with copolyesters, olefin resins, metal soaps, etc. For example, carbon black manufactured by Mitsubishi Chemical Corporation and commercially available as "MA100" can be used. As a processed pigment, processed pigment manufactured by Sumika Color Co., Ltd. and commercially available as "Black EXC-8A1893" can be used.

[0041] (Compounds containing carbodiimide groups)

[0042] The resin mixtures disclosed herein comprise compounds having carbodiimide groups (-N=C=N-). In this disclosure, the compounds having carbodiimide groups are preferably polycarbodiimides (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 carrying out a decarboxylation condensation reaction.

[0043] Examples of organic isocyanates include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. Specific examples of polycarbodiimides include aromatic polycarbodiimides, such as poly(4,4'-diphenylmethane carbodiimide), poly(p-phenylene carbodiimide), poly(m-phenylene carbodiimide), poly(diisopropylphenyl carbodiimide), and poly(triisopropylphenyl carbodiimide), as well as alicyclic polycarbodiimides, such as poly(dicyclohexylmethane carbodiimide). These polycarbodiimides can be used alone or in any combination of two or more.

[0044] Among these polycarbodiimides, aliphatic polycarbodiimides are preferred. For example, those commercially available as “Carbodilite HMV-15CA,” “Carbodilite LA-1,” and “Carbodilite HMV-5CA-LC” manufactured by Nisshinbo Chemical Inc. can be used.

[0045] In this disclosure, compounds having a carbodiimide group preferably include compounds represented by the following formula (1).

[0046]

[0047] Where R is an alkylene group having 1 to 12 carbon atoms, and n is an integer greater than 2 and less than 10.

[0048] (other)

[0049] In this disclosure, the carbon black is 1.0 part by weight or more and 20.0 parts by weight or less based on 100 parts by weight of binder resin, preferably 3.0 parts by weight or more and 10.0 parts by weight or less based on 100 parts by weight of binder resin, more preferably 3.6 parts by weight or more and 8.3 parts by weight or less based on 100 parts by weight of binder resin.

[0050] Furthermore, in this disclosure, based on 100 parts by weight of the adhesive resin, the mass of the compound having a carbodiimide group is 3.0 parts by weight or more and 64.0 parts by weight or less, preferably 15.0 parts by weight or more and 64.0 parts by weight or less, more preferably 18.3 parts by weight or more and 58.3 parts by weight or less.

[0051] By doing so as described above, thin, black-colored biaxially stretched PET resin articles can be obtained from the resin mixtures of this disclosure. In this disclosure, the structure of the chemical substances and their mass ratios can be confirmed by nuclear magnetic resonance (NMR) or gas chromatography-mass spectrometry (GC-MS).

[0052] <Resin Granules>

[0053] The resin granules disclosed herein comprise the resin mixture of the present disclosure. The resin granules are obtained, for example, by melting the resin mixture of the present disclosure in a resin extruder (single-screw, twin-screw, etc.), then extruding the resin into a string (also called a strand), cooling the string in a water tank, etc., and then cutting the string into granules using a cutting device called a strand cutter.

[0054] <Prefabricated components>

[0055] The preform disclosed herein comprises the resin mixture of the present disclosure and a polyester resin. The preform is an intermediate product for biaxial stretch forming produced from the resin mixture of the present disclosure or the resin granules of the present disclosure, and has a test tube-like shape. Biaxially stretched molded articles can be produced by placing the preform in a mold and blow molding the preform under heating, thereby causing the preform in the mold to expand.

[0056] <Biaxially stretched molded products>

[0057] The biaxially stretched molded article of this disclosure comprises the resin mixture of this disclosure and a polyester resin. Regarding the biaxially stretched molded article of this disclosure, while holding the preform of this disclosure at a predetermined temperature (e.g., about 100°C in the case of PET resin), gas is introduced into the preform of this disclosure to cause the preform to expand (for blow molding), thereby increasing the overall length and diameter of the preform; in other words, the preform has uniaxial stretching with an increased overall length and uniaxial stretching with an increased diameter.

[0058] A molded article that has undergone two uniaxial stretching processes is called a biaxial stretch molded article. Typical examples of biaxial stretch molded articles include PET bottles for beverages and various container PET bottles such as soy sauce containers, cosmetic containers, and toner containers for holding copier toner, and this disclosure is applicable to these applications.

[0059] <Paint Bottle>

[0060] The first embodiment of this disclosure will be described below with reference to the accompanying drawings. Figure 1 This is a schematic structural diagram showing a four-color image forming apparatus using an electrophotographic system, and includes the main body of the image forming apparatus 80. This image forming apparatus 80 is a so-called intermediate transfer tandem type image forming apparatus in which the four-color image forming units are arranged side-by-side on an intermediate transfer belt.

[0061] In this image forming apparatus 80, image formation is performed as follows: First, based on printing data, an electrostatic latent image is formed on a photosensitive drum 17 (17y, 17m, 17c, 17bk) using exposure equipment 50 (50y, 50m, 50c, 50bk). The formed electrostatic latent image is then developed using developing equipment 21 (21y, 21m, 21c, 21bk) to form a toner image.

[0062] In this image forming apparatus 80, a toner image is transferred to an intermediate transfer body 62 via a primary transfer unit 60 (60Y, 60M, 60c, 60bk), and then transferred to paper material S supplied from the paper feeding device 63 via a secondary transfer unit 64 (64a, 64b). Next, in the image forming apparatus 80, the toner image transferred to the paper material S is fixed onto the paper material S by a fixing unit 68, after which the paper material is discharged onto the paper discharge tray 70.

[0063] In this image forming apparatus 80, a toner image is formed by the developing apparatus 21, and a removable 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, in Figure 6 An example of the shape of toner bottle 3 is shown in the figure.

[0064] <Second Implementation Plan>

[0065] The second implementation scheme relates to a method for producing biaxially stretched and formed articles.

[0066] The method disclosed herein for producing biaxially stretched molded articles includes preparing resin granules from a resin mixture, preparing a preform from the resin granules and polyester resin, and blow molding the preform. The resin mixture comprises a binder resin, carbon black, and a compound having carbodiimide groups. Based on 100 parts by mass of the binder resin, the carbon black is 1.0 parts by mass or more and 20.0 parts by mass or less, and the compound having carbodiimide groups is 3.0 parts by mass or more and 64.0 parts by mass or less.

[0067] The items described in the first implementation scheme may overlap with those described in the second implementation scheme; therefore, these descriptions are sometimes omitted.

[0068] Next, embodiments of the method for producing resin mixtures according to this disclosure will be described.

[0069] (Preparation of resin granules)

[0070] Methods for producing biaxially stretched molded articles involve preparing resin granules from a resin mixture. First, binder resin, carbon black, and carbodiimide are melt-blended, and then the resin mixture (sometimes described below as "masterbatch") is produced by extrusion and granulation.

[0071] There are no particular limitations on the melt-blending unit, and as... Figure 4 As shown, known units, such as twin-screw extruders, can be used. For example, a PCM-46 (manufactured by Ikegai Corp) 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-mixed.

[0072] A metered amount of binder resin 203, carbon black 204, and carbodiimide 205 are supplied to hopper 202. There is no particular limitation on the melt mixing temperature, but when the binder resin is a polyester resin, the melt mixing temperature is, for example, 200 to 300°C, preferably 240 to 280°C.

[0073] The resin, which is extruded into a strip, is passed through a water tank 207 to cool it, and then cut with a cutter 206 to obtain a resin mixture 208 in granular form.

[0074] The carbon black in the resin mixture has the function of coloring the toner bottle black. In order to color the toner bottle black, carbon black needs to be mixed in an amount of 1.0 to 20.0 parts by weight based on 100 parts by weight of binder resin.

[0075] The polycarbodiimide in the resin mixture has the property of reacting with the polyester resin used as the material for the toner bottle. The carbodiimide groups of the polycarbodiimide crosslink with the terminal carboxyl groups of the polyester resin. The polycarbodiimide has multiple carbodiimide groups, therefore, the carbodiimide groups can bond to multiple ends of the polyester resin.

[0076] Carbon black typically acts as a nucleus for polyester resins and accelerates their crystallization. However, the molecular weight can be increased by polycarbodiimide, thus slowing down the crystallization of polyester resins. To achieve the effect of delaying the crystallization rate of polyester resins, carbodiimide needs to be added in an amount of 3.0 to 64.0 parts by weight based on 100 parts by weight of binder resin in the resin mixture.

[0077] The resin mixture according to this disclosure is used by mixing the resin mixture with the material of the toner bottle during biaxial stretch blow molding, as described later.

[0078] A method could be considered that carbon black and polycarbodiimide are added directly to the polyester resin in the toner bottle without pre-preparing a resin mixture of carbon black and polycarbodiimide. However, molding a resin mixture of carbon black, polycarbodiimide, and binder resin can better suppress carbon black crystallization.

[0079] When the resin mixture is molded, a small amount of polycarbodiimide crosslinks with the binder resin in the resin mixture, and the molecular weight of the binder resin increases. A large amount of high molecular weight binder resin is present around the carbon black in the resin mixture.

[0080] If a resin mixture is added to the material of a toner bottle, the resin mixture is dispersed, but the resin mixture produces an environment in which a large amount of high molecular weight resin exists around the carbon black, and crystallization using carbon black as a nucleus is not easy to occur.

[0081] On the other hand, methods for preparing resin granules also include adding carbon black and polycarbodiimide directly to the polyester resin in the toner bottle without pre-preparing a resin mixture of carbon black and polycarbodiimide. In this case, the carbon black is in contact with the polyester resin that has not yet been cross-linked with polycarbodiimide, and sometimes the carbon black is used as a nucleus for the crystallization of the polyester resin.

[0082] The resin mixture according to this disclosure is used by mixing the resin mixture with the material of the toner bottle during biaxial stretch blow molding, as described later.

[0083] (Preparation of prefabricated components)

[0084] The method disclosed herein for producing biaxially stretched molded articles includes preparing a preform from resin granules and polyester resin. An embodiment of the method for producing preforms using a resin mixture according to this disclosure via biaxial stretch blow molding will be described below.

[0085] like Figure 2 As shown, a preform 104 having a test tube shape is formed by injection molding. Specifically, a material obtained by premixing the material of a toner bottle and a masterbatch is fed into an injection molding machine 101, the material is heated and melted by a heating cylinder 105, and the molten material is injected into preform molds 102 and 103 by a screw 106 to form the preform 104.

[0086] The toner bottle is made of polyester resin such as PET or PEN, and preferably the binder resin of the masterbatch is matched with the material of the toner bottle. In the method for producing biaxially stretched molded articles disclosed herein, when preparing the preform, based on 100 parts by weight of polyester resin, the mass of resin granules is preferably 0.8 parts by weight or more and 2.0 parts by weight or less, more preferably 1.1 parts by weight or more and 1.7 parts by weight or less, and particularly preferably 1.4 parts by weight. By doing so as described above, in the method for producing biaxially stretched molded articles disclosed herein, it is easier to produce biaxially stretched molded articles by stretch blow molding.

[0087] The material and masterbatch of the toner bottle in a molten state are stirred using screw 106. Then, the carbon black in the masterbatch is dispersed in the material of the toner bottle, thereby forming a black preform 104.

[0088] Furthermore, the polycarbodiimide in the masterbatch reacts with the polyester resin used as a toner bottle material. Specifically, the carbodiimide groups and the terminal carboxyl groups of the polyester resin are bonded to each other. Moreover, since the polycarbodiimide molecule has multiple carbodiimide groups, multiple polyester resins are bonded together via the polycarbodiimide.

[0089] Typically, during the cooling process of preform 104, which begins immediately after injection, crystallization occurs due to the heat of preform 104. However, polyester resins with increased molecular weight due to bonding to polycarbodiimide have a low crystallization rate and can suppress the crystallization of preform 104.

[0090] (Blow molding of prefabricated parts)

[0091] The method disclosed herein for producing biaxially stretched molded articles includes blow molding a preform. For example... Figure 3 As shown, biaxial stretch blow molding (biaxial stretch forming) is performed. First, the preform 104 is placed in the heating furnace 107 and heated to a temperature that allows it to be stretched.

[0092] The molecular weight also increases through the reaction of the polyester resin with polycarbodiimide, thereby slowing down the crystallization rate and inhibiting crystallization when the heating time is within 3 minutes. After heating, the heated preform 104 is removed from the heating furnace 107 and placed at the opening of a blow mold 108 with an internal cavity, which is formed by combining the left mold 108-1 and the right mold 108-2.

[0093] Preferably, the preform is placed at the opening of the blow mold 108 within a short time (e.g., within 10 seconds) so that the temperature of the heated preform does not drop before biaxial stretching begins.

[0094] A heated preform 104 disposed inside a blow mold 108 is stretched longitudinally using a stretching bar 109. This stretching is called a primary stretch. In this case, it is preferable to allow gas to flow into the preform so that the preform 104 does not come into contact with the stretching bar 109, and the pressure of the gas in this case is called the primary blow molding pressure.

[0095] After the first stretching, gas 110 is introduced into the preform through the preform opening 113 to cause the preform to expand horizontally (circumferentially). This is called secondary stretching. In this case, the gas pressure is called the secondary blow molding pressure. Examples of gases blown in include air, nitrogen, carbon dioxide, and argon.

[0096] Through these primary and secondary stretching processes, the preform 104 expands in the direction indicated by arrow 301 and comes into close contact with the inner wall of the blow molding die 108, while in this state, the preform is cooled and solidified. Subsequently, the left mold 108-1 and the right mold 108-2 of the blow molding die 108 are separated, thereby removing the blow-molded article 112 from the blow molding die 108. In this blow-molded article 112, stretching has been performed in both longitudinal and transverse directions, thus obtaining a molded article with high strength.

[0097] During the injection stretch blow molding process, it is important that the preform is in a non-crystalline state (non-crystalline, i.e., amorphous). If the preform is in an amorphous state and reaches the blow molding temperature, the preform is soft and deformable. Therefore, by performing blow molding, i.e. biaxial stretch molding, PET is stretched and crystallized along the stretching direction, and a bottle with high strength can be formed.

[0098] Examples of injection stretch blow molding methods include the one-stage method and the two-stage method. The one-stage method utilizes the residual heat of the preform immediately after it is removed from the mold to stretch blow mold the preform as is or after temperature control. The two-stage method involves cooling the preform to room temperature once, and then subjecting the preform to temperature control again for stretch blow molding.

[0099] In the 1-stage method, as... Figure 5 As shown, after the preform 104 is injection molded in the injection molding machine 101, the cooling during injection molding is completed in a short time of less than 10 seconds so that the temperature of the preform 104 does not fall below the glass transition temperature of PET.

[0100] In this method, the preform is immediately held at a blow molding temperature (e.g., 80°C to 120°C), heated, and blow molded to obtain a blow-molded article 112 (blow-molded bottle). An injection molding machine integrated with the blow molding equipment is used.

[0101] The two-stage method involves, after injection molding of the preform, cooling it below the glass transition temperature of PET, removing it, and then heating it to the blow molding temperature (e.g., 80°C to 120°C) using separate injection molding and blow molding equipment.

[0102] In the one-stage process, the preform is not cooled below its glass transition temperature; therefore, the one-stage process is preferred because less energy is required for reheating, as in the two-stage process. However, after injection molding, the time spent holding the preform at the crystallization temperature of PET is extended, making isothermal crystallization of PET more likely than in the two-stage process. The crystallization temperature of this PET is approximately 130°C to 200°C.

[0103] Therefore, in both the one-stage and two-stage methods, the resin mixture of this disclosure achieves the effect of delaying crystallization, but in particular, the effect is higher in the one-stage method.

[0104] (other)

[0105] In the method for producing biaxially stretched molded articles disclosed herein, the resin mixture comprises a binder resin, carbon black, and a compound having carbodiimide groups. Based on 100 parts by weight of the binder resin, the carbon black comprises 1.0 part by weight or more and 20.0 parts by weight or less, preferably 3.0 part by weight or more and 10.0 parts by weight or less, more preferably 3.6 parts by weight or more and 8.3 parts by weight or less. The compound having carbodiimide groups comprises 3.0 parts by weight or more and 64.0 parts by weight or less, preferably 15.0 parts by weight or more and 64.0 parts by weight or less, more preferably 18.3 parts by weight or more and 58.3 parts by weight or less. Since the above description overlaps with the description of the first embodiment, further description is omitted.

[0106] [Example 1]

[0107] The present disclosure will be described in detail below using examples. However, the present disclosure is not limited to these examples.

[0108] In the following embodiments, unless otherwise stated, "%" means "mass%".

[0109] <Forming of Resin Mixtures>

[0110] The resin mixture is shaped using a twin-screw extruder (PCM-46 manufactured by Ikegai Corp). PET, carbon black, and polycarbodiimide are melt-blended while being uniformly and quantitatively fed. The mixing ratios of PET, carbon black, and polycarbodiimide are varied as shown in Table 1.

[0111] After melt mixing at a melt mixing temperature of 260°C, a screw rotation speed of 250 rpm, a degassing pressure of -0.05 MPa, and a discharge rate of 80 kg / h, the resulting resin mixture was granulated. The carbon black and polycarbodiimide used here were powders. By heat-treating the granulated resin mixture at 180°C for 4 hours, materials suitable for injection stretch blow molding were obtained. These materials are designated MB(1-1), MB(1-2), and MB(1-3).

[0112] (Table 1)

[0113]

[0114] <Forming of blow-molded bottles>

[0115] The PET and resin granules MB(1-1), MB(1-2), or MB(1-3), which are used as the material for the toner bottle, are premixed and then fed into a one-step stretch blow molding machine (ASB-70DPH manufactured by Nissei ASB machine Co., Ltd.).

[0116] This equipment is used for injection stretch blow molding via a one-stage process. The mixing ratios between the material in the toner bottle and MB(1-1), MB(1-2), or MB(1-3) are shown in Tables 2-1, 2-2, and 2-3. The materials described in Tables 2-1 to 2-3 are used in a dry state.

[0117] (Table 2-1)

[0118]

[0119] (Table 2-2)

[0120]

[0121] (Table 2-3)

[0122]

[0123] The aforementioned one-step stretch blow molding machine can continuously perform injection molding to obtain preforms and biaxial stretch blow molding of preforms to obtain bottle-shaped products.

[0124] In the molding machine, the screw diameter of the injection molding machine is 54mm.

[0125] First, prepare a mold capable of forming a preform with an outer diameter of 30 mm, a wall thickness of 3.7 mm, and a length of 220 mm as the mold for forming the preform. Then, form the preform under the following forming conditions.

[0126] - Screw diameter: 54mm

[0127] - Screw position before filling the chamber with resin mixture: 95mm

[0128] -Injection speed

[0129] Until the screw moves forward 5mm: 50% of the maximum speed

[0130] Until the screw moves forward another 20mm: 30% of the maximum speed.

[0131] Until the screw moves forward another 35mm: 25% of the maximum speed.

[0132] PV switching position: 35mm

[0133] -Injection pressure

[0134] - Until PV switch: 12.0MPa

[0135] - After PV switching: 4.5MPa (holding pressure)

[0136] -Voltage holding time after PV switch

[0137] -4.57 seconds

[0138] Heating cylinder temperature: 280℃

[0139] - Cooldown: 8.0 seconds

[0140] - Mold temperature: 18℃

[0141] In an injection molding machine, the materials described in Tables 2-1 to 2-3 are melted and mixed to obtain preforms colored black with carbon black contained in MB(1-1), MB(1-2), and MB(1-3). The color of MB(1-2) is lighter than that of MB(1-1) and MB(1-3) due to a lower mixing ratio of carbon black. From a designability point of view, there are no issues with the materials.

[0142] Furthermore, the polycarbodiimide contained in MB(1-1), MB(1-2), and MB(1-3) crosslinks with PET, increasing the molecular weight of PET. As a result, crystallization is delayed, and soft, non-crystallized preforms can be formed. In MB(1-3), the mixing ratio of polycarbodiimide is high, thus delaying crystallization more significantly compared to the crystallization in MB(1-1) and MB(1-2).

[0143] The preform is removed from the preform forming mold and conveyed to the insulation station of the one-step stretch blow molding machine. The insulation conditions are as follows.

[0144] -Insulation temperature of precast components

[0145] The position at 10% of the total length of the precast component from the top: 180°

[0146] At a position 25% of the total length of the precast component from the top: 200℃

[0147] At a point 50% of the total length of the precast component from the top: 200℃

[0148] The position at 75% of the total length of the precast component from the top: 180°

[0149] The preform, adjusted to the aforementioned temperature, is then placed inside a mold sculpted into the shape of a toner bottle, and biaxial stretch blow molding is performed to shape the toner bottle. The mold temperature is adjusted to 18°C. The surface temperature of the preform immediately before blow molding is 100°C.

[0150] The specific blow molding process will be described. A stretch bar is inserted into the preform through an opening and moved forward until it contacts the top of the preform. The air pressure used to drive the stretch bar is then set to 1.2 MPa to move it further forward. 0.5 seconds after the stretch bar has moved further forward, primary air is injected into the preform through the opening. The pressure of the primary air is set to 1.0 MPa.

[0151] Subsequently, after the initial air injection, secondary air was introduced 0.15 seconds later. The pressure of the secondary air was set to 2.9 MPa. Then, air was injected into the interior of the preform after 7.0 seconds from the start of the initial air injection. The pressure inside the preform was then allowed to return to atmospheric pressure over 2.5 seconds. This yielded a thin black toner bottle with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm.

[0152] [Example 2]

[0153] <Forming of Resin Mixtures>

[0154] MB(1-1) is shaped in the same manner as in Example 1.

[0155] <Forming of blow-molded bottles>

[0156] The colorant bottle is made from recycled materials. These recycled materials are obtained by recycling used beverage PET bottles and crushing them. Commercially available "HPR" manufactured by Pantech Corporation is used.

[0157] Crushed PET has a low bulk density and cannot be trapped in the screw of the injection molding machine of the biaxial stretch blow molding machine. Therefore, in order to increase the bulk density, PET is melt-blended by an extruder.

[0158] According to the formulation in Table 3, melt compounding was performed using a twin-screw extruder (PCM-46 manufactured by Ikegai Corp). The extrusion conditions are as follows.

[0159] Temperature: 260℃

[0160] Screw rotation speed: 20 rpm

[0161] Discharge rate: 50 kg / h

[0162] (Table 3)

[0163]

[0164] The material, which had been melt-mixed and granulated under the above conditions, was subjected to a heat treatment at 180°C for 4 hours to form granules for injection molding. This material is called PCR(2-1). The IV value of PCR(2-1) is 0.64 dL / g.

[0165] After premixing the recycled PET PCR (2-1) and MB (1-1), the mixture was fed into a one-step stretch blow molding machine (ASB-70DPH manufactured by Nissei ASB machine Co., Ltd.). The mixing ratio between PCR (2-1) and MB (1-1) is shown in Table 4. The material described in Table 4 was fed into the molding machine in a dry state.

[0166] (Table 4)

[0167]

[0168] The preform was formed by one-step stretch blow molding in the same manner as in Example 1.

[0169] PCR (2-1) and MB (1-1) are melt-blended using the screw of an injection molding machine. A preform is then obtained, colored black with carbon black contained in MB (1-1).

[0170] Furthermore, the polycarbodiimide contained in MB(1-1) crosslinks with the PET in PCR(2-1), increasing the molecular weight of PET. The increased molecular weight of PCR(2-1) thus reduces the crystallization rate even when carbon black, which acts as a nucleation point, is included, resulting in a soft preform at blow molding temperatures.

[0171] By blow molding the preform in the same manner as in Example 1, a black toner bottle derived from recycled materials with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm was obtained.

[0172] [Example 3]

[0173] <Forming of Resin Mixtures>

[0174] The resin mixture was shaped using the same twin-screw extruder and molding conditions as in Example 1. PET, carbon black, and polycarbodiimide were uniformly and quantitatively fed at the mixing ratios shown in Table 5, while the PET, carbon black, and polycarbodiimide were melt-blended, and a powdered processing pigment was used as the carbon black. By heat-treating the granulated resin mixture at 180°C for 4 hours, a material suitable for injection stretch blow molding was obtained. This material is designated MB(3-1).

[0175] (Table 5)

[0176]

[0177] <Forming of blow-molded bottles>

[0178] After premixing PET and MB(3-1) as the materials for the toner bottle, the mixture is fed into a one-step stretch blow molding machine (ASB-70DPH manufactured by Nissei ASB machine Co., Ltd.). The mixing ratio between the toner bottle material and MB(3-1) is shown in Table 6. The materials described in Table 6 are used in a dry state.

[0179] (Table 6)

[0180]

[0181] PET and MB(3-1) are melt-blended using the screw of an injection molding machine. A preform is then obtained, colored black with carbon black contained in MB(3-1). The polycarbodiimide contained in MB(3-1) crosslinks with PET, increasing the molecular weight of the PET.

[0182] The carbon black used in this article is a processed pigment whose surface is coated with resin. Therefore, carbon black and PET rarely come into direct contact with each other, and carbon black is not used as a nucleus for PET crystals.

[0183] As described above, the molecular weight of PET is increased. Furthermore, the use of coated carbon black allows the crystallization rate of the preform to be slowed down compared to that in Examples 1 and 2. The preform formed by this technique becomes soft even at blow molding temperatures.

[0184] By blow molding the preform in the same manner as in Example 1, a black toner bottle derived from recycled materials with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm was obtained.

[0185] [Example 4]

[0186] <Forming of Resin Mixtures>

[0187] In the embodiments described so far, the binder resin and the biaxially stretched molded article are each made of PET, but the same effect can be achieved with PEN. The resin mixture is formed using the same twin-screw extruder and the same forming conditions as in Example 1.

[0188] PEN is used as a binder resin, and PEN, carbon black, and polycarbodiimide are melt-blended while being uniformly and quantitatively supplied. By heat-treating the granulated resin mixture at 180°C for 4 hours, a material suitable for injection stretch blow molding is obtained. This material is designated MB(4-1).

[0189] (Table 7)

[0190]

[0191] <Forming of blow-molded bottles>

[0192] After premixing PEN and MB(4-1), the mixture is fed into a one-step stretch blow molding machine (ASB-70DPH manufactured by Nissei ASB machine Co., Ltd.). The mixing ratio between PEN and MB(4-1) is shown in Table 8. The materials described in Table 8 are used in a dry state.

[0193] (Table 8)

[0194]

[0195] The preform was formed by one-step stretch blow molding in the same manner as in Example 1.

[0196] PEN and MB(4-1) are melt-blended using the screw of an injection molding machine. A preform is then obtained, colored black with carbon black contained in MB(4-1).

[0197] Furthermore, the polycarbodiimide contained in MB(4-1) crosslinks with PEN, and the molecular weight of PEN increases. The increased molecular weight of PEN allows for a slower crystallization rate, even when carbon black is included as a nucleation point, resulting in a soft preform at blow molding temperatures.

[0198] The preform is removed from the preform forming mold and conveyed to the insulation station of the one-step stretch blow molding machine. The insulation conditions are as follows.

[0199] -Insulation temperature of precast components

[0200] The location 10% of the total length of the precast component from the top: 270℃

[0201] At a position 25% of the total length of the precast component from the top: 300℃

[0202] At a point 50% of the total length of the precast component from the top: 300℃

[0203] The location at 75% of the total length of the precast component from the top: 270℃

[0204] Subsequently, the preform, adjusted to the aforementioned temperature, is placed inside a mold sculpted into the shape of a toner bottle, and the preform is biaxially stretched and blow-molded to form the toner bottle. The mold temperature is adjusted to 18°C. The surface temperature of the preform immediately before blow molding is 150°C.

[0205] The specific blow molding process will be described. A stretch bar is inserted into the preform through an opening and moved forward until it contacts the top of the preform. The air pressure used to drive the stretch bar is then set to 1.2 MPa to move it further forward. 0.5 seconds after the stretch bar has moved further forward, primary air is injected into the preform through the opening. The pressure of the primary air is set to 1.0 MPa.

[0206] Subsequently, 0.15 seconds after the initial air injection, secondary air was introduced. The pressure of the secondary air was set to 2.9 MPa. Then, after 7.0 seconds from the start of the initial air injection, air was injected into the interior of the precast component.

[0207] Subsequently, the pressure inside the preform is restored to atmospheric pressure over a period of 2.5 seconds. This yields a thin, black biaxially stretched molded article containing PEN, which has higher heat resistance, gas barrier properties, and mechanical strength compared to PET, with an outer diameter of 60 mm, a wall thickness of 0.35 mm, and a length of 440 mm.

[0208] According to embodiments of this disclosure, a carbon black-colored masterbatch can be provided to suppress the crystallinity of the preform in injection stretch blow molding of thin PET resin, thus obtaining a thin biaxial stretch molded PET resin with a black color.

[0209] In addition, a masterbatch colored with carbon black can be provided to suppress the crystallinity of preforms in injection stretch blow molding of low molecular weight recycled PET resin, thus enabling injection stretch blow molded articles that use low molecular weight recycled PET resin as raw material and are colored black.

[0210] The technologies described in this specification are technologies that can help achieve sustainable societies, such as decarbonized / circular societies.

[0211] Although this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A resin mixture comprising: Adhesive resin; Carbon black; and Compounds containing carbodiimide groups, The binder resin is based on 100 parts by weight, wherein the carbon black is 1.0 parts by weight or more and 20.0 parts by weight or less, and the compound having a carbodiimide group is 3.0 parts by weight or more and 64.0 parts by weight 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 adhesive 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 cracking carbon black and channel black.

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

7. The resin mixture according to claim 1, wherein the compound having a carbodiimide group comprises a compound represented by formula (1): Where R is an alkylene group having 1 to 12 carbon atoms, and n is an integer greater than 2 and less than 10.

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

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

10. A resin granule comprising a resin mixture according to any one of claims 1 to 7.

11. A method for producing biaxially stretched formed articles, comprising the following steps: Resin granules are prepared from resin mixtures; Preforms are prepared from the resin granules and polyester resin; and The preform is blow-molded; in The resin mixture comprises binder resin, carbon black, and a compound having carbodiimide groups, and Based on 100 parts by weight of the adhesive resin, the carbon black comprises 1.0 part by weight or more and 20.0 parts by weight or less, and the compound having a carbodiimide group comprises 3.0 part by weight or more and 64.0 parts by weight or less.

12. The method for producing biaxially stretched molded articles according to claim 11, wherein in the step of preparing the preform, the mass of the resin granules is 0.8 parts by mass and 2.0 parts by mass or less, based on 100 parts by mass of the polyester resin.

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