Resin molding method and resin sorting method

Abstract

To provide a resin molding method capable of forming a molded article by estimating specific physical properties of a resin having unknown physical properties by a simple method and molding the resin under molding conditions adjusted on the basis of the estimated physical properties.SOLUTION: The resin-molding method comprises a physical property-estimating step S01 of irradiating resins with electromagnetic waves including near infrared rays, measuring the intensity of the electromagnetic waves reflected on the surfaces of the resins, and estimating the flowability of the resins on the basis of information on the intensity of the electromagnetic waves including the intensity of the electromagnetic waves, and a resin-molding step S02 of adjusting resin-molding conditions on the basis of the estimated flowability of the resins and molding the resins under the adjusted resin-molding conditions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin molding method and a resin selection method. [Background technology]

[0002] In recent years, growing environmental awareness has led to the promotion of the use of recycled resins made from waste plastics. Currently, only waste plastics with easily recyclable materials and minimal changes in physical properties are selected and used as raw materials for recycled resins. However, in the future, society will increasingly demand a reduction in the global environmental impact, and demand for recycled plastics is expected to increase. Accordingly, it will be necessary to obtain waste plastics from various sources to ensure quality and quantity. In this case, low-quality waste plastics are likely to be mixed in. Examples of low-quality waste plastics include those that have been recycled multiple times and have deteriorated significantly. Other examples of low-quality waste plastics include those that contain multiple additives and impurities.

[0003] Therefore, it is necessary to quickly detect the physical properties of waste plastics that are used as raw materials for recycled resins at receiving sites, processing sites, etc. It is also necessary to manage the quality of recycled resins made from waste plastics.

[0004] One method for managing the quality of waste plastics and the like uses the MFR of thermoplastic resin as an index (see, for example, Patent Document 1). This is a method for managing the quality of thermoplastic resins by estimating the MFR of the thermoplastic resin. MFR stands for melt mass flow rate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-128032 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method described in Patent Document 1 has a problem in that it is difficult to perform highly accurate measurements on low-viscosity thermoplastic resins with large MFR.

[0007] The present invention has been made in consideration of the above problems and circumstances, and aims to provide a resin molding method that can estimate specific physical properties of a resin whose physical properties are unknown in a simple manner, adjust molding conditions based on the estimated physical properties, and mold the resin under the estimated molding conditions. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present inventors have conducted extensive research, focusing on the relationship between electromagnetic wave intensity information and "ease of resin flow." Electromagnetic wave intensity information is information including the electromagnetic wave intensity of electromagnetic waves reflected from the surface of a resin when the resin is irradiated with electromagnetic waves. As a result, the present inventors have found that "ease of resin flow" can be estimated based on electromagnetic wave intensity information including the electromagnetic wave intensity, and have arrived at the present invention. That is, the above-mentioned problems according to the present invention are solved by the following means.

[0009] 1. A physical property estimation step of irradiating a resin with electromagnetic waves including near-infrared rays, measuring the electromagnetic wave intensity of the electromagnetic waves reflected on the surface of the resin, and estimating the flowability of the resin based on electromagnetic wave intensity information including the electromagnetic wave intensity; a molding step of adjusting molding conditions based on the estimated flowability of the resin and molding the resin under the molding conditions; A resin molding method comprising the steps of:

[0010] 2. The physical property estimation step The solid resin is heated to form a molten resin, and the electromagnetic wave intensity of the molten resin is measured; cooling the molten resin to form a solid resin, and measuring the electromagnetic wave intensity of the solid resin; 2. The resin molding method according to claim 1, further comprising the step of estimating the ease of flow of the resin based on the electromagnetic wave intensity information including the two obtained electromagnetic wave intensities.

[0011] 3. When the solid resin is heated to form the molten resin, the heating is performed at a heating rate of 5 to 25°C / min, 3. The resin molding method according to item 2, wherein the molten resin is cooled to form the solid resin at a cooling rate of 1 to 10° C. / min.

[0012] 4. The physical property estimation step calculating the reflectance of each electromagnetic wave based on the electromagnetic wave intensities at the molten resin and the solid resin; The reflectance or the reflectance to which a transformation has been applied is used as reflectance data, In the reflectance data of the molten resin, two specific wavelengths are selected, and the reflectance data at the larger wavelength λa is designated as a and the reflectance data at the smaller wavelength λb is designated as b. ΔR1 is a value obtained by subtracting b from a, In the reflectance data of the solid resin, two specific wavelengths are selected, and the reflectance data at the larger wavelength λc is defined as c and the reflectance data at the smaller wavelength λd is defined as d. The value obtained by subtracting d from c is defined as ΔR2, Calculate ΔR1 / ΔR2, 3. The resin molding method according to claim 2, further comprising the step of estimating the ease of flow of the resin using ΔR1 / ΔR2 as the electromagnetic wave intensity information.

[0013] 5. The solid resin is heated, and the temperature at which it changes from a solid state to a molten state is defined as T1°C. The electromagnetic wave intensity of the molten resin is measured in the temperature range of T1 to T1+10°C. 3. The resin molding method according to claim 2, wherein the electromagnetic wave intensity of the solid resin is measured in a temperature range of 20 to 40°C.

[0014] 6. The physical property estimation step 5. The resin molding method according to claim 4, further comprising the step of estimating the ease of flow of the resin based on the electromagnetic wave intensity information using a calibration curve that correlates the value of ΔR1 / ΔR2 with the ease of flow of the resin.

[0015] 7. The wavelength λa and the wavelength λc are wavelengths included in the wavelength range of 1585 to 1605 nm, 5. The resin molding method according to claim 4, wherein the wavelength λb and the wavelength λd are wavelengths included in the wavelength range of 1535 to 1550 nm.

[0016] 8. The resin molding method according to claim 1 or 2, wherein the estimated resin flowability is a melt mass flow rate.

[0017] 9. The molding step is a step of molding the resin while adjusting the molding conditions, the adjusted molding conditions are molding conditions adjusted while acquiring the electromagnetic wave intensity information of the resin during molding; 3. The resin molding method according to claim 1 or 2.

[0018] 10. The molding step is a step of heating and molding the resin, 3. The resin molding method according to claim 1, wherein the molding conditions include a condition for heating the resin.

[0019] 11. The resin molding method according to claim 1 or 2, wherein the resin is a mixture of multiple resins.

[0020] 12. The resin molding method according to claim 1 or 2, wherein the resin is a recycled resin.

[0021] 13. The resin molding method according to claim 1 or 2, wherein the physical property estimation step and the molding step are repeated multiple times.

[0022] 14. Irradiating a resin with electromagnetic waves including near-infrared rays, measuring the electromagnetic wave intensity of the electromagnetic waves reflected on the surface of the resin, and estimating the flowability of the resin based on electromagnetic wave intensity information including the electromagnetic wave intensity; A resin selection method in which molding conditions are adjusted based on the estimated flowability of the resin, and the resin is selected in accordance with the obtained molding conditions.

[0023] 15. The resin selection method according to item 14, wherein the resin is a recycled resin. [Effects of the Invention]

[0024] The present invention provides a resin molding method that allows for the estimation of unknown resin properties using a simple method and for obtaining a molded product under molding conditions adjusted based on the estimated properties. The present invention also provides a resin selection method that allows for the estimation of unknown resin properties using a simple method and for selecting a resin to conform to molding conditions adjusted based on the estimated properties.

[0025] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0026] When electromagnetic waves are irradiated onto a resin, heat conduction occurs from the surface of the resin toward the interior of the resin. This causes a change in the state of the surface of the resin that is irradiated with electromagnetic waves. The surface of the resin that is irradiated with electromagnetic waves reflects the electromagnetic waves, so it is also called the "reflecting surface of the resin." Furthermore, when electromagnetic waves are irradiated onto a resin, the state of the reflecting surface of the resin differs depending on the melting speed of the resin.

[0027] It is presumed that the reflectance data of electromagnetic waves when irradiated onto a resin changes due to changes in the state of the resin's reflective surface as described above. Reflectance data is reflectance or "reflectance converted." On the other hand, it is presumed that the thermal conduction inside the resin and the melting speed of the resin affect the resin's melt mass-flow rate (MFR). For these reasons, it is presumed that the electromagnetic wave reflectance data, which reflects the state of the resin's reflective surface, is correlated with the resin's melt mass-flow rate (MFR). [Brief explanation of the drawings]

[0028] [Figure 1]3 is a flowchart showing a resin molding method according to the present embodiment. [Figure 2] 10 is a graph showing the relationship between the wavelength of a reflected electromagnetic wave and reflectance data. [Figure 3] 1 is a calibration curve showing the relationship between ΔR1 / ΔR2 and melt mass flow rate (MFR). [Figure 4] FIG. 1 is a schematic diagram illustrating an apparatus for heating a resin and measuring electromagnetic wave intensity, which is used in an example of the present invention. [Figure 5] FIG. 1 is a schematic diagram illustrating an apparatus for heating a resin and measuring electromagnetic wave intensity, which is used in an example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] As shown in FIG. 1 , one embodiment of the resin molding method of the present invention includes a physical property estimation step S01 and a molding step S02. The physical property estimation step S01 is a step of irradiating a resin with electromagnetic waves, measuring the electromagnetic wave intensity, and estimating the resin's flowability. The electromagnetic waves irradiated to the resin include near-infrared rays. The measured electromagnetic wave intensity is the electromagnetic wave intensity of the electromagnetic waves reflected by the resin surface. The resin's flowability is estimated based on electromagnetic wave intensity information including the electromagnetic wave intensity. The molding step S02 is a step of adjusting molding conditions based on the estimated resin's flowability and molding the resin under the molding conditions. Because the resin molding method of this embodiment is configured as described above, it is possible to estimate the physical properties of a resin with unknown physical properties in a simple manner. Furthermore, the resin molding method of this embodiment can produce a molded product under molding conditions adjusted based on the estimated physical properties. This feature is a technical feature common to or corresponding to each of the following embodiments. FIG. 1 is a flowchart showing the resin molding method of this embodiment.

[0030] The physical property estimation step S01 is preferably a step of estimating the flowability of the resin based on the electromagnetic wave intensity information including the electromagnetic wave intensities of both the molten resin and the solid resin. The molten resin is obtained by heating a solid resin to form a molten resin. The solid resin is obtained by cooling the molten resin to form a solid resin. In this way, by setting the physical property to be estimated as "the flowability of the resin," it becomes possible to estimate the flowability in a simple manner from the electromagnetic wave intensity information including the electromagnetic wave intensities of the molten resin and the solid resin.

[0031] When the solid resin is heated to form the molten resin, it is preferable to heat it at a heating rate of 5 to 25°C / min. And when the molten resin is cooled to form the solid resin, it is preferable to cool it at a cooling rate of 1 to 10°C / min. By setting the heating rate and cooling rate within specific ranges in this way, it is possible to obtain the electromagnetic wave intensity information that has a better correlation with the flowability of the resin.

[0032] The physical property estimation step S01 is preferably a step of estimating the flowability of the resin using ΔR1 / ΔR2 as electromagnetic wave intensity information. The electromagnetic wave reflectivities of the molten resin and the solid resin are calculated based on the electromagnetic wave intensities in the molten resin and the solid resin. Therefore, reflectivity is a type of "electromagnetic wave intensity information including electromagnetic wave intensity." Here, reflectivity or "reflectivity with a transformation applied" is referred to as reflectivity data. Since reflectivity data is reflectivity or "reflectivity with a transformation applied," it is also a type of "electromagnetic wave intensity information including electromagnetic wave intensity." Furthermore, the following ΔR1, ΔR2, and "ΔR1 / ΔR2," calculated from the reflectivity data, are also "electromagnetic wave intensity information including electromagnetic wave intensity." ΔR1 is the value obtained by subtracting reflectivity data b from reflectivity data a. Reflectivity data a is the reflectivity data at the larger wavelength λa, selected from two specific wavelengths (λa, λb) in the reflectivity data of the molten resin. The reflectance data b is the reflectance data at the small wavelength λb. ΔR2 is the value obtained by subtracting the reflectance data d from the reflectance data c. The reflectance data c is the reflectance data at the large wavelength λc when two specific wavelengths λc and λd are selected from the reflectance data of the solid resin. The reflectance data d is the reflectance data at the small wavelength λd. ΔR1 / ΔR2 is the value obtained by dividing ΔR1 by ΔR2. By performing the physical property estimation step S01 as described above, it is possible to obtain the electromagnetic wave intensity information that has a higher correlation with the resin flowability. The above-mentioned "reflectance transformed" is the reflectance transformed, for example, by the "SNV transformation" described below. The "reflectance transformed" can be used to estimate the resin flowability when the electromagnetic wave intensity information such as ΔR1 / ΔR2 is calculated.

[0033] When a solid resin is heated and the temperature at which it changes from a solid state to a molten state is defined as T1°C, it is preferable to measure the electromagnetic wave intensity of the molten resin in a temperature range of T1 to "T1 + 10°C." It is also preferable to measure the electromagnetic wave intensity of the solid resin in a temperature range of 20 to 40°C. By measuring the electromagnetic wave intensity in this temperature range, it is possible to stably obtain electromagnetic wave intensity information that has a higher correlation with the flowability of the resin.

[0034] The physical property estimation step S01 is preferably a step of estimating the resin flowability based on the electromagnetic wave intensity information using a calibration curve that correlates the ΔR1 / ΔR2 value with the resin flowability. By using the calibration curve that shows the correspondence relationship between the ΔR1 / ΔR2 value and the resin flowability, the resin flowability can be estimated in a simple manner. Then, a molded product can be obtained under molding conditions adjusted based on the estimated resin flowability.

[0035] The wavelengths λa and λc are preferably wavelengths within the range of 1585 to 1605 nm. The wavelengths λa and λc are more preferably 1595 nm. The wavelengths λb and λd are preferably wavelengths within the range of 1535 to 1550 nm. The wavelengths λb and λd are more preferably 1542 nm. By setting the wavelengths λa, λb, λc, and λd as described above, the correlation between the value of ΔR1 / ΔR2 and the ease of resin flow can be further enhanced. This allows the ease of resin flow to be more accurately estimated from the value of ΔR1 / ΔR2. The wavelengths λa, λb, λc, and λd are preferably the same as the wavelengths λa, λb, λc, and λd used to create a calibration curve.

[0036] The estimated resin flowability is preferably the melt mass flow rate (MFR). The MFR, which indicates the resin flowability, is an important index when filling a heated and molten resin into a mold for injection molding. Therefore, by estimating the MFR and adjusting the molding conditions, it is possible to produce a good molded product.

[0037] The molding step S02 is preferably a step of molding a resin while adjusting molding conditions. The adjusted molding conditions are preferably molding conditions that are adjusted while acquiring electromagnetic wave intensity information of the resin during molding. Furthermore, the molding conditions are preferably adjusted so as to suppress variations in the quality of the molded product obtained by molding. In this case, the molding conditions are adjusted multiple times during the resin molding process. That is, during the resin molding process, it is preferable to acquire electromagnetic wave intensity information of the resin before molding multiple times while the molding process is progressing, and to readjust the molding conditions each time the electromagnetic wave intensity information is acquired and perform the resin molding. By adjusting the molding conditions multiple times during the resin molding process, variations in the quality of the molded product can be suppressed. The resin for which the electromagnetic wave intensity is to be acquired is preferably obtained by sampling the resin in the cylinder of the injection molding machine to obtain the electromagnetic wave intensity information. Furthermore, it is preferable to perform resin sampling every 10 to 15 molded products before the next injection.

[0038] It is preferable to repeat the physical property estimation step S01 and the molding step S02 multiple times. This means that, assuming that one cycle is the physical property estimation step S01 followed by the molding step S02, multiple cycles are repeated. In this case, the molding conditions are adjusted multiple times during the resin molding as described above. The adjusted molding conditions are molding conditions adjusted while obtaining electromagnetic wave intensity information of the resin during molding. By adjusting the molding conditions multiple times during the resin molding, it is possible to suppress fluctuations in the quality of the molded product.

[0039] Preferably, the molding step S01 is a step of heating and molding a resin, and the molding conditions include conditions for heating the resin. More preferably, the molding step S01 is a step of heating, melting, and molding a resin. This makes it easier to adjust the molding conditions based on the estimated ease of flow of the resin.

[0040] It is preferable that the resin used in resin molding is a recycled resin. The resin molding method of this embodiment can estimate the physical properties of recycled resins whose physical properties are unknown and mold them. Therefore, it is preferable to mold recycled resins containing waste plastics, etc., using the resin molding method of this embodiment.

[0041] In one embodiment of the resin selection method of the present invention, a resin is irradiated with electromagnetic waves including near-infrared rays. The electromagnetic wave intensity of the electromagnetic waves reflected by the resin surface is then measured, and the flowability of the resin is estimated based on the electromagnetic wave intensity information including the electromagnetic wave intensity. The resin selection method of this embodiment then adjusts molding conditions based on the estimated resin flowability, and selects a resin in accordance with the obtained molding conditions. This allows the resin selection method of this embodiment to easily estimate the physical properties of a resin whose physical properties are unknown, and to select a resin in accordance with molding conditions adjusted based on the estimated physical properties.

[0042] In the resin sorting method of this embodiment, the resin is preferably a recycled resin. The resin sorting method of this embodiment can estimate the physical properties of recycled resins whose physical properties are unknown and sort them. Therefore, it is preferable to sort recycled resins containing waste plastics, etc., using the resin sorting method of this embodiment.

[0043] The present invention, its components, and modes and aspects for carrying out the present invention will be described in detail below. In this application, the symbol "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower limit and upper limit.

[0044] 1.Resin molding method [Physical property estimation process] In the resin molding method of this embodiment, the physical property estimation step irradiates the resin with electromagnetic waves including near-infrared rays and measures the electromagnetic wave intensity of the electromagnetic waves reflected by the resin surface. The physical property estimation step then estimates the flowability of the resin based on electromagnetic wave intensity information including the electromagnetic wave intensity. Hereinafter, the electromagnetic waves reflected by the resin surface may also be referred to as "reflected electromagnetic waves." Furthermore, the intensity of the reflected electromagnetic waves may also be referred to as "reflected electromagnetic wave intensity."

[0045] [Electromagnetic waves] The electromagnetic waves irradiated to the resin are electromagnetic waves including near-infrared rays. Hereinafter, the electromagnetic waves irradiated to the resin will also be referred to as "irradiated electromagnetic waves." Near-infrared rays are electromagnetic waves with wavelengths of 800 nm to 2.5 μm. The irradiated electromagnetic waves may include the entire wavelength range of near-infrared rays, but preferably include at least the wavelength range of 935 nm to 1720 nm. It is even more preferable that the irradiated electromagnetic waves include the wavelength range of 1450 nm to 1650 nm. This makes it possible to accurately estimate the flowability of the resin based on electromagnetic wave intensity information including the reflected electromagnetic wave intensity.

[0046] The intensity of the irradiated electromagnetic wave is preferably 10 W to 1000 W, more preferably 100 W to 400 W. By setting the intensity of the irradiated electromagnetic wave within this range, the intensity of the reflected electromagnetic wave can be measured satisfactorily.

[0047] The device for irradiating the resin with electromagnetic waves is not particularly limited as long as it can irradiate the resin with electromagnetic waves having the above wavelength range at the above intensity, and an example of such a device is HySiL1500 (manufactured by Kahoku Lighting Solutions Co., Ltd.).

[0048] To estimate the ease of flow of resin based on electromagnetic wave intensity information, including reflected electromagnetic wave intensity, the area of ​​resin to be irradiated with electromagnetic waves is set to 100 cm 2 ~500cm 2 100cm is preferred. 2 If the area of ​​the resin irradiated with electromagnetic waves is too large, the resin and the equipment must also be large. Therefore, the area should be 500 cm or less. 2 It is preferable that:

[0049] The electromagnetic waves may be irradiated onto the resin all at once. Alternatively, the electromagnetic waves may be irradiated onto a part of the resin by scanning the resin, so that the electromagnetic waves are irradiated onto the entire resin. When scanning the resin with the electromagnetic waves, the electromagnetic waves may be moved, or the resin may be moved.

[0050] The irradiation angle when irradiating the resin with electromagnetic waves is preferably in the range of 0° to 60°, where 0° is the angle when the light is incident parallel to the normal to the resin surface. The electromagnetic waves can be irradiated onto the resin surface at an angle in the range of 0° to 90°. This allows the electromagnetic waves to be efficiently irradiated onto the resin.

[0051] [Electromagnetic wave intensity measurement] The intensity of the reflected electromagnetic waves reflected by the resin surface can be measured using a device capable of measuring near-infrared intensity. For example, the Specim FX-17 (product name) (manufactured by Specim) can be used. The Specim FX-17 can measure the intensity of electromagnetic waves in the near-infrared wavelength range of 900 nm to 1700 nm. Here, measuring the electromagnetic wave intensity provides a spectrum, which is a record of the intensity distribution for each wavelength of the electromagnetic wave.

[0052] In the physical property estimation step, it is preferable to first heat a solid resin to form a molten resin and measure the reflected electromagnetic wave intensity of the molten resin. Then, it is preferable to cool the molten resin to form a solid resin and measure the reflected electromagnetic wave intensity of the solid resin. Furthermore, it is preferable to estimate the flowability of the resin based on electromagnetic wave intensity information including the obtained two reflected electromagnetic wave intensities. This allows the flowability of the resin to be estimated with high accuracy.

[0053] When a solid resin is heated to form a molten resin, it is preferable to heat it at a heating rate of 5 to 25°C / min. The heating rate is more preferably 10 to 20°C / min. By using a heating rate within this range, the flowability of the resin can be accurately estimated. If the heating rate is slower than 5°C / min, it may be difficult to determine the heat transfer rate of the resin itself. If the heating rate is faster than 25°C / min, there may be a lot of overshooting beyond the target heating temperature.

[0054] When the molten resin is cooled to form a solid resin, it is preferable to cool it at a cooling rate of 1 to 10°C / min. The cooling rate is more preferably 5 to 10°C / min. By using a cooling rate within this range, the flowability of the resin can be accurately estimated. If the cooling rate is slower than 1°C / min, crystallization of the resin may occur. If the cooling rate is faster than 10°C / min, cooling may proceed unexpectedly, making it difficult to collect data.

[0055] The method for heating the resin is not particularly limited, and any method that can heat the entire resin at a predetermined rate may be used, such as heating with a heat gun or irradiating with a laser.

[0056] The temperatures at which the reflected electromagnetic wave intensity is measured are as follows: When a solid resin is heated, the temperature at which it changes from a solid state to a molten state is defined as T1°C. The electromagnetic wave intensity of the molten resin is preferably measured in the temperature range of T1 to T1 + 10°C. The temperature range is more preferably T1 to T1 + 5°C. By measuring the reflected electromagnetic wave intensity in this temperature range, the reflected electromagnetic wave intensity can be measured accurately. Furthermore, the electromagnetic wave intensity of the solid resin is preferably measured in the temperature range of 20 to 40°C. The temperature range is more preferably 32 to 38°C. By measuring the reflected electromagnetic wave intensity in this temperature range, the reflected electromagnetic wave intensity can be measured accurately.

[0057] [Electromagnetic wave intensity information] In the physical property estimation step, it is preferable to calculate the reflectance of each electromagnetic wave based on the reflected electromagnetic wave intensity in the molten resin and the solid resin. The reflectance of the electromagnetic wave is the ratio (%) of the reflected electromagnetic wave intensity to the intensity of the irradiated electromagnetic wave. Therefore, the reflectance of the electromagnetic wave is one type of electromagnetic wave intensity information that includes the electromagnetic wave intensity (reflected electromagnetic wave intensity).

[0058] As described above, electromagnetic wave intensity is expressed as a spectrum, which is a record of the intensity distribution for each wavelength of the electromagnetic wave. The spectrum of electromagnetic wave intensity is expressed as a graph with wavelength on the horizontal axis and electromagnetic wave intensity on the vertical axis over the range of wavelengths measured. Reflectance data calculated based on the electromagnetic wave intensity is expressed as a graph with wavelength on the horizontal axis and reflectance on the vertical axis.

[0059] The relationship between the wavelength of reflected electromagnetic waves and reflectance data will be further explained. FIG. 2 is a graph showing the relationship between the wavelength of reflected electromagnetic waves and reflectance data. In the graph of FIG. 2, the horizontal axis represents wavelength (nm). In the graph of FIG. 2, the vertical axis represents reflectance data. This reflectance data is "reflectance converted into SNV." SNV is an abbreviation for "Standard Normal Variate." Hereinafter, reflectance converted into SNV will also be referred to as "SNV-converted reflectance." SNV conversion is performed by first considering the reflectance distribution (spectrum) calculated from the reflected electromagnetic wave intensity as a set of reflectances and subtracting the "average value of all reflectances" from "each reflectance" in the set (distribution) of reflectances. Then, SNV conversion is performed by dividing each of the "values ​​obtained by subtracting the average value of all reflectances from each reflectance" by the "standard deviation of all reflectances." In other words, the reflectance data on the vertical axis is expressed by the formula "(reflectance - average value of all reflectances) / σ," where σ is the standard deviation of all reflectances. As a result, the reflectance corresponding to each wavelength is converted into an "SNV converted reflectance" corresponding to each wavelength. FIG. 2 can also be said to be a graph of a spectrum showing the distribution of SNV converted reflectance for each wavelength of reflected electromagnetic waves. This shows the relationship between the wavelength of reflected electromagnetic waves and the SNV converted reflectance. This makes it possible to suppress baseline shift when measuring the electromagnetic wave intensity spectrum of reflected electromagnetic waves. Here, in this specification, a recorded intensity distribution for each wavelength of electromagnetic waves, as described above, is referred to as a spectrum, and a recorded distribution of reflectance data calculated from this intensity distribution is also referred to as a spectrum.

[0060] Next, it is preferable to calculate ΔR1 / ΔR2 from the relationship between the wavelength of the reflected electromagnetic wave and the SNV converted reflectance. ΔR1 / ΔR2 has a strong correlation with the flowability of the resin, particularly the MFR. In Figure 2, graph M shows the relationship between the "wavelength of the reflected electromagnetic wave" and the "SNV converted reflectance" for a molten resin. The graph in Figure 2 is sometimes referred to as a "wavelength-SNV converted reflectance graph." Graph S shows the relationship between the "wavelength of the reflected electromagnetic wave" and the "SNV converted reflectance" for a solid resin. In graph M, two specific wavelengths are selected, and the SNV converted reflectance at the larger wavelength λa of the two wavelengths is defined as a, and the SNV converted reflectance at the smaller wavelength λb is defined as b. ΔR1 is calculated by subtracting b from a. Similarly, in graph S, two specific wavelengths are selected, and the SNV converted reflectance at the larger wavelength λc is defined as c, and the SNV converted reflectance at the smaller wavelength λd is defined as d. ΔR2 is calculated by subtracting d from c. Then, ΔR1 / ΔR2 is calculated. Then, it is preferable to estimate the ease of resin flow using ΔR1 / ΔR2 as electromagnetic wave intensity information. It is preferable that wavelength λa and wavelength λc are the same wavelength. It is preferable that wavelength λb and wavelength λd are the same wavelength. It is also preferable that wavelengths λa to λd are the same as wavelengths λa to λd used when creating the calibration curve. In this embodiment, the reflectance data is SNV converted reflectance, but it is also possible to estimate the ease of resin flow even if the reflectance data is reflectance.

[0061] The melting temperature of a resin can be determined using a "wavelength-SNV conversion reflectance graph." Graph S, a spectrum based on the reflected electromagnetic wave intensity from a solid resin, has a downwardly convex minimum absorption peak Sm between 1450 nm and 1650 nm. In the graph of Figure 2, this absorption peak Sm is formed near a wavelength of 1550 nm. Such an absorption peak Sm is formed in a "wavelength-SNV conversion reflectance graph" for a solid resin. On the other hand, graph M, a spectrum based on the reflected electromagnetic wave intensity from a molten resin, does not have a downwardly convex minimum absorption peak between 1450 nm and 1650 nm. Graph S has upwardly convex maximum regions on both the long-wavelength side and the short-wavelength side of the wavelength at which the absorption peak Sm is formed. In contrast, graph M has a maximum region on the long-wavelength side of the "wavelength at which the absorption peak Sm in graph S is formed," but not on the short-wavelength side. This shows that when a solid resin is heated to a molten state, the absorption peak Sm disappears along with the local maximum region on the shorter wavelength side relative to the wavelength at which the absorption peak Sm is formed. In other words, when the absorption peak Sm disappears, the solid resin becomes molten. Therefore, while increasing the temperature of the solid resin, a "wavelength-SNV conversion reflectance graph" based on the reflected electromagnetic wave intensity is created for each specific temperature. The measured temperature at which the absorption peak Sm disappears is at least the temperature at which the resin is molten. The reflected electromagnetic wave intensity of the molten resin is preferably measured in the temperature range of T1 to T1 + 10°C. Therefore, it is preferable that the difference between the measured temperature at which the absorption peak Sm first disappears and the measured temperature at which the solid state absorption peak Sm exists immediately before that is less than 30°C. This means that the temperature at which the absorption peak Sm first disappears is included in the temperature range of at least T1 to T1 + 10°C.

[0062] [Prediction of resin flowability] In the resin molding method of this embodiment, the estimated resin flowability is used to adjust the molding conditions for resin molding. The estimated resin flowability is not particularly limited as long as it can be used to adjust the molding conditions for resin molding, but it is preferably the melt mass flow rate (MFR). By adjusting the molding conditions based on the MFR, a good molded product can be produced.

[0063] MFR is measured in accordance with JIS K 7210-1 and is expressed in grams of resin per 10 minutes. Specifically, first, a cylinder with a die attached to the bottom is heated. Then, the heated cylinder is filled with resin. After 5 minutes of preheating, a load is applied to the cylinder, causing the resin to be extruded from the die at the bottom of the cylinder. The amount of resin (g) per unit time (10 min) at this time is then measured and taken as the MFR. MFR can be measured using this method. "min" means "minutes."

[0064] The physical property estimation step is preferably a step of estimating the resin flowability based on electromagnetic wave intensity information using a calibration curve relating the value of "ΔR1 / ΔR2" to the "resin flowability." The electromagnetic wave intensity information is preferably "ΔR1 / ΔR2" of the resin whose physical properties are to be estimated. Furthermore, as described above, the "resin flowability" is preferably expressed in terms of melt mass-flow rate (MFR). Figure 3 shows a calibration curve showing the relationship between ΔR1 / ΔR2 and melt mass-flow rate (MFR).

[0065] A calibration curve can be created, for example, as follows: The MFRs of multiple resins are measured. The type of resin for which the MFR is measured is not particularly limited. The resins preferably include resins with an MFR value of 400 (g / 10 min) or more and resins with an MFR value of 2 (g / 10 min) or less. Examples of resins used to create the calibration curve include HDPE. HDPE is an abbreviation for high-density polyethylene. The number of resins for which the MFR is measured is not particularly limited, but is preferably 5 or more. It is also preferable that the ΔR1 / ΔR2 values ​​of the resins for which the MFR is measured fall within an appropriate interval suitable for creating a calibration curve. Furthermore, when molding recycled resins, the multiple resins with different MFRs used to create the calibration curve can be appropriately determined based on the MFR range of resins recovered from the market.

[0066] For the resin for which the MFR is to be measured, the reflected electromagnetic wave intensity is measured as electromagnetic wave intensity information using the above method, and "ΔR1 / ΔR2" is calculated using the above method. Then, as shown in FIG. 3, it is preferable to calculate a formula that expresses the relationship between the MFR of each resin and "ΔR1 / ΔR2" and use this formula as a calibration curve. In addition, when the relational formula (regression curve) showing the relationship between ΔR1 / ΔR2 and MFR is obtained, the square of the correlation coefficient (R 2 ) is preferably 0.75 or more.

[0067] The method for estimating the MFR of a resin is as follows. The reflected electromagnetic wave intensity of the resin is measured using the above method, and the electromagnetic wave intensity information "ΔR1 / ΔR2" is calculated using the above method. The MFR value is read from the obtained "ΔR1 / ΔR2" value using the above calibration curve. The MFR may also be calculated from the "ΔR1 / ΔR2" value using the mathematical formula on which the calibration curve is based.

[0068] [resin] The resin used for molding in the resin molding method of this embodiment is preferably a thermoplastic resin. The resin may also be a mixture of multiple resins. The resin is preferably a resin molded by injection molding. Furthermore, the resin may be a recycled resin made from waste plastic. When it is necessary to check the MFR value for each resin used for molding, such as recycled resin made from waste plastic, the resin molding method of this embodiment allows for easy confirmation of the MFR, adjustment of molding conditions, and resin molding. The resin used for molding in the resin molding method of this embodiment preferably has an MFR value of 0.2 (g / 10 min) or more and 400 (g / 10 min) or less.

[0069] The resin used for molding in the resin molding method of this embodiment preferably has a reflectance of 20% or more for electromagnetic waves of a specific wavelength. The reflectance is more preferably 25% or more, and particularly preferably 40% or more. A higher reflectance is preferable, with an upper limit of approximately 90%. By ensuring that the reflectance of the resin is within this range, the physical properties of the resin can be accurately estimated in the physical property estimation step. The electromagnetic waves of the specific wavelength are the following two types of electromagnetic waves. One is electromagnetic waves with a wavelength in the range of 1585 to 1605 nm. The other is electromagnetic waves with a wavelength in the range of 1535 to 1550 nm. In other words, it is preferable that the reflectances of these two types of electromagnetic waves are both within the above ranges. In particular, it is preferable that the reflectance of electromagnetic waves with a wavelength of 1595 nm and the reflectance of electromagnetic waves with a wavelength of 1542 nm are both 20% or more, more preferably 25% or more, and particularly preferably 40% or more.

[0070] The resin used for molding in the resin molding method of this embodiment can be, for example, HDPE, etc. A mixture of multiple types of the above resins may also be used in the resin molding method of this embodiment.

[0071] In the resin molding method of this embodiment, as described above, recycled resin made from waste plastics can be used as the resin used for molding. In this case, the waste plastics may be pre-consumer or post-consumer materials. Pre-consumer materials refer to materials not used in products on the market. Examples of pre-consumer materials include offcuts, defective products, and discarded inventory from the product manufacturing process. Post-consumer materials refer to materials shipped to the market as products. Post-consumer materials include both used and unused materials. The recycled resin may contain a single type of raw material or may be a mixture of multiple types of raw materials. The raw material for the recycled resin may be multiple types of waste plastics, one type of waste plastic and other materials, or one type of waste plastic. The raw material for the recycled resin may be multiple types of waste plastics and other materials, or one type of waste plastic.

[0072] [Molding process] The molding step in the resin molding method of this embodiment is a step of adjusting molding conditions based on the estimated resin flowability and molding the resin under those molding conditions. In the resin molding method of this embodiment, the molding step is preferably a step of injection molding the resin. The molding step is, for example, a step of heating and melting the resin, filling a mold with the molten resin, cooling and solidifying the resin in the mold, and removing the solidified resin from the mold to obtain a molded product. In this way, the molding step is preferably a step of heating and molding the resin.

[0073] An injection molding machine is used for injection molding. The injection molding machine preferably has an injection device that melts resin and fills it into a mold, and a mold that molds the molten resin to produce a molded product. The injection molding machine also preferably has a mold clamping device that opens and closes the mold.

[0074] The molding conditions in the molding step include conditions for heating the resin, etc. More specifically, the molding conditions include the temperature at which the resin is melted in the injection device, the injection pressure when the resin is injected into the mold from the injection device, the temperature of the resin in the mold, the mold temperature, etc. Among these, it is particularly preferable to use the temperature at which the resin is melted and the injection pressure as molding conditions for the resin, based on the flowability of the resin, such as MFR.

[0075] When carrying out the resin molding method of this embodiment, it is preferable to confirm in advance the relationship between the resin flowability, such as MFR, and the molding conditions to be adjusted in the injection molding machine. It is then preferable to determine the molding conditions based on the resin flowability, such as MFR, estimated in the physical property estimation step and the above relationship. It is then preferable to mold the resin under the obtained molding conditions.

[0076] For example, when the flowability of a resin is defined as MFR, it is preferable to determine molding conditions by injection molding a plurality of resins with different MFRs. The MFRs of the resins with different MFRs preferably cover the range of MFRs that can be estimated in the physical property estimation process. Furthermore, it is preferable to select a sufficient number of resins to determine molding conditions so that molding conditions can be adjusted regardless of the estimated MFR of the resin to be molded within the range of MFRs.

[0077] The molding step is preferably a step of molding a resin while adjusting molding conditions. The adjusted molding conditions are preferably molding conditions that are adjusted while acquiring information on the electromagnetic wave intensity of the resin during molding. Furthermore, the molding conditions are preferably adjusted so as to suppress fluctuations in the quality of the molded product obtained by molding. In this case, the molding conditions are adjusted multiple times during resin molding. By adjusting the molding conditions multiple times during resin molding, it is possible to suppress fluctuations in the quality of the molded product. Regarding the resin for which the electromagnetic wave intensity is to be acquired, it is preferable to acquire the electromagnetic wave intensity information by sampling the resin in the cylinder of an injection molding machine. Furthermore, it is preferable to perform resin sampling every time 10 to 15 molded products are produced, before the next injection.

[0078] It is preferable to repeat the physical property estimation step and the molding step multiple times. This means that, assuming that one cycle is the physical property estimation step followed by the molding step, the steps are repeated multiple times. In this case, the molding conditions are adjusted multiple times during the resin molding. The adjusted molding conditions are molding conditions that are adjusted while obtaining information on the electromagnetic wave intensity of the resin during molding. By adjusting the molding conditions multiple times during the resin molding, it is possible to suppress fluctuations in the quality of the molded product.

[0079] 2. Resin selection method The resin selection method of this embodiment first irradiates a resin with electromagnetic waves including near-infrared rays and measures the electromagnetic wave intensity of the electromagnetic waves reflected by the resin surface. The resin selection method of this embodiment then estimates the flowability of the resin based on electromagnetic wave intensity information including the electromagnetic wave intensity. This is the same as the physical property estimation step in the resin molding method of this embodiment. The resin selection method of this embodiment then preferably adjusts the molding conditions based on the estimated resin flowability and selects resins in accordance with the obtained molding conditions. The adjustment of the molding conditions is the same as the adjustment of the molding conditions in the resin molding method of this embodiment. Resins with the same molding conditions can be mixed and molded.

[0080] In the resin selection method of this embodiment, the resin to be selected is preferably a recycled resin. By selecting recycled resin, recycled resins with the same molding conditions can be collected, mixed, and molded, allowing the recycled resin to be used efficiently. [Example]

[0081] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C).

[0082] Example 1 (1) Resin molding method 1. Physical property estimation process <Resin> The resin used for molding was market recovered product A. Market recovered product A is a resin recovered from the market of used plastic containers and packaging. Market recovered product A is HDPE resin with an MFR of 1.25 g / 10 min. The reflectance of market recovered product A to electromagnetic waves with a wavelength of 1595 nm was 84.83%, and the reflectance to electromagnetic waves with a wavelength of 1542 nm was 54.60%. The respective reflectances are shown in Table 1. In Table 1, "reflectance 1" is the reflectance when electromagnetic waves with a wavelength of 1595 nm are reflected from the resin. "reflectance 2" is the reflectance when electromagnetic waves with a wavelength of 1542 nm are reflected from the resin. Market recovered product A was white to the naked eye.

[0083] The recovered product A was coarsely pulverized using a plastic pulverizer, Model 14 (E014) (manufactured by Fujitex Co., Ltd.). The coarsely pulverized recovered product A was then fed into an extruder (HAAKE Process 11 (manufactured by Thermo Scientific)), kneaded, and extruded to form strands. The resulting strands were pelletized using a pelletizer (LNS-50SCE (manufactured by Giken Kogyo Co., Ltd.)).

[0084] The pellets of recovered product A were dried at 80°C for 4 hours. The dried pellets were then molded using an injection molding machine (Babyplast (Rambaldi)) to obtain test pieces measuring 80 mm in length, 10 mm in width, and 4.0 mm in height. The cylinder temperature of the injection molding machine was set to 260°C, and the mold temperature was set to 50°C. The molding conditions for preparing the test pieces may vary depending on the resin.

[0085] <Electromagnetic wave intensity measurement> Two HySiL1500 (product name) (manufactured by Kahoku Lighting Solutions Co., Ltd.) were used as light sources for irradiating electromagnetic waves. The electromagnetic waves used for measuring the electromagnetic wave intensity included wavelengths of 900 nm to 2150 nm. The electromagnetic wave intensity of each of the two light sources was 200 W.

[0086] The camera used for measuring the near-infrared intensity was Specim FX-17 (product name) (manufactured by Specim).

[0087] The resin was heated using a 1000 W heat gun as a heat source. The heat gun used was PJ-208A (manufactured by Ishizaki Electric Works Co., Ltd.).

[0088] The electromagnetic wave intensity measurement was performed as follows. First, as shown in FIG. 4, the test piece 1 was placed on a heat-resistant table 2, and a thermocouple 4 was attached to the test piece 1. Then, the test piece 1 and the thermocouple 4 were fixed to the heat-resistant table 2 using heat-resistant tape. The thermocouple 4 was connected to a temperature display unit 6. The heat-resistant table 2 was then placed on a sliding plate 3. The sliding plate 3 can slide between the "position where the heat source 7 is installed" and the "position where the light source 8 and camera 9 are installed." The sliding plate 3 slides on rails (not shown). The position where the heat source 7 is installed is also referred to as the "heating position." The position where the light source 8 and camera 9 are installed is also referred to as the "camera position." The test piece 1 was heated at the heating position, and then the sliding plate 3 was slid to the camera position. After that, the test piece 1 was irradiated with electromagnetic waves, and the reflected electromagnetic wave intensity was measured. The heat source 7, light source 8, camera 9, and rails (not shown) were fixed to an aluminum rack (not shown). FIG. 4 is a schematic diagram illustrating an apparatus for heating a resin and measuring the electromagnetic wave intensity, which is used in the examples of the present invention.

[0089] Electromagnetic wave intensity measurements were performed on molten recovered product A (molten resin) and on solid recovered product A (solid resin) obtained after solidifying molten recovered product A. Measurement of the electromagnetic wave intensity of molten recovered product A was performed when the temperature of solid recovered product A was increased while measuring the electromagnetic wave intensity, and the measurement was performed once it was confirmed that the solid recovered product A had reached a molten state. Therefore, in order to measure the electromagnetic wave intensity of molten recovered product A, measurements of the electromagnetic wave intensity of solid recovered product A were repeatedly performed while increasing the temperature.

[0090] The electromagnetic wave intensity of the molten market recovered product A was measured as follows. First, as shown in Figure 4, a slide plate 3 on which a test piece 1 and a heat-resistant stand 2 were placed was placed at the heating position. Then, the slide plate 3 was heated to 100°C by a heat source 7. The temperature was increased at a rate of 20°C / min.

[0091] Then, as shown in Fig. 5, the slide plate 3 on which the test piece 1 and the heat-resistant stand 2 were placed was slid to the "camera position." Then, when the temperature of the test piece 1 reached 95°C through natural cooling, an electromagnetic wave was irradiated from a light source 8, and the intensity of the reflected electromagnetic wave was measured with a camera 9. Fig. 5 is a schematic diagram showing an outline of an apparatus for heating a resin and measuring the intensity of the electromagnetic wave, which is used in the examples of the present invention.

[0092] At this time, the reflected electromagnetic wave intensity was measured using camera 9 in the wavelength range of 935 nm to 1720 nm, which corresponds to near-infrared wavelengths. Then, the reflectance for each wavelength was calculated from the obtained intensity distribution for each wavelength of the electromagnetic wave. Then, as shown in the graph in Figure 2, the wavelength was plotted on the horizontal axis and the "SNV converted reflectance" on the vertical axis, and the relationship between wavelength and "SNV converted reflectance" was obtained (not shown).

[0093] After that, heating at the heating position and measuring the reflected electromagnetic wave intensity at the camera position were repeated, increasing the temperature by 20°C each time. When the downward-convex minimum absorption peak (corresponding to Sm in the graph in Figure 2) disappeared in the relationship between wavelength and "SNV converted reflectance," it was determined that recovered product A had melted. The ΔR1 measured when the reflected electromagnetic wave intensity of recovered product A in this molten state was 0.2115. ΔR1 is the value obtained by subtracting the "SNV converted reflectance" at a wavelength of 1542 nm (λb) from the "SNV converted reflectance" at a wavelength of 1595 nm (λa). The "SNV converted reflectance" at a wavelength of 1595 nm (λa) is reflectance data a. The "SNV converted reflectance" at a wavelength of 1542 nm (λb) is reflectance data b. The state where the downward-convex minimum absorption peak disappeared corresponds to graph M in the graph in Figure 2.

[0094] The electromagnetic wave intensity of the solid market recovered product A was measured as follows. After measuring the reflected electromagnetic wave intensity of the market recovered product A in a molten state, the market recovered product A was moved to the heating position and cooled to 35 °C at a rate of 10 °C / min. The cooling method was air blowing cooling. Then, the market recovered product A was moved to the camera position and the reflected electromagnetic wave intensity was measured to obtain the relationship between the wavelength and the "SNV conversion reflectance" (corresponding to graph S in Figure 2). The ΔR2 at that time was 0.2390. ΔR2 is the value obtained by subtracting the value of the "SNV conversion reflectance" at a wavelength of 1542 nm (λd) from the value of the "SNV conversion reflectance" at a wavelength of 1595 nm (λc). The "SNV conversion reflectance" at a wavelength of 1595 nm (λc) is the reflectance data c. The "SNV conversion reflectance" at a wavelength of 1542 nm (λd) is the reflectance data d.

[0095] From the obtained ΔR1 and ΔR2, the value of ΔR1 / ΔR2 was 0.885.

[0096] Using the calibration curve in Figure 3 showing the relationship between ΔR1 / ΔR2 and MFR, an estimated value of MFR was obtained from the above value of ΔR1 / ΔR2. The estimated value of MFR was 1.2 (g / 10 min). As a result of measuring the MFR of the market recovered product A by the "Method for Measuring MFR" shown below, the MFR of the market recovered product A was 1.25 (g / 10 min). The results are shown in Table 1. Table 1 is a table showing the results of evaluating the estimation accuracy of the physical property estimation process in the resin molding method of Example 1, etc. In Table 1, "A" in the resin column means the market recovered product A. "Estimation accuracy" indicates the ratio of the estimated value to the actually measured value of MFR.

[0097]

Table 1

[0098] <Method for Measuring MFR> Using a Melt Indexer G-02 (manufactured by Toyo Seiki Seisakusho), the MFR of the resin is determined according to a method compliant with JIS K 7210-1. Seven grams of resin pellets are precisely weighed and placed in a cylinder at 230°C. A 5 kg load is applied to the cylinder, and the mass of the resin extruded from the die at the bottom of the cylinder per 10 minutes is measured. The resulting mass of resin per 10 minutes is the MFR.

[0099] <How to create a calibration curve> The ΔR1 / ΔR2 values ​​for multiple resins with different MFRs were determined using the same method as described above in the "Resin" and "Electromagnetic Wave Intensity Measurement" sections. In this case, market recalled product A in the "Resin" and "Electromagnetic Wave Intensity Measurement" sections was replaced with each of the multiple resins with different MFRs. The multiple resins used to create the calibration curve were six types of resins with known compositions. These six types of resins were R-PE, R-PP, R-PA, R-PET, R-PBT, and R-POM.

[0100] The temperature used to measure the electromagnetic wave intensity of the molten resin was 110°C. Therefore, in order to measure the electromagnetic wave intensity of the resin in a molten state, the operation of "repeatedly measuring the electromagnetic wave intensity of the solid resin while increasing the temperature" was not performed.

[0101] The MFR of the above six resins was measured by the above MFR measurement method.

[0102] The calibration curve shown in Figure 3 was created from the obtained ΔR1 / ΔR2 values ​​and MFR values ​​of each resin. The ΔR1 / ΔR2 values ​​and MFR values ​​of each resin are also shown in Table 1. The formula for the calibration curve is "y = 2 × 10 7 ×e -18.78x , R 2= 0.9957". In Table 2, R-POM stands for recycled polyoxymethylene, R-PP stands for recycled polypropylene, R-PE stands for recycled polyethylene, R-PET stands for recycled polyethylene terephthalate, R-PA stands for recycled polyamide, specifically recycled nylon, and R-PBT stands for recycled polybutylene terephthalate.

[0103] [Table 2]

[0104] 2. Molding process The molding method was injection molding. The injection molding machine used was a "Babyplast" manufactured by Rambaldi. This machine has an injection unit that melts the resin and fills it into a mold, and a mold that molds the molten resin to create a molded product. The injection unit has a horizontal structure, and the resin placed in a hopper is heated and injected into the mold with a screw, and finally removed from the mold.

[0105] For this injection molding machine, we confirmed the molding conditions for each of several "resins with different MFRs" in advance. Therefore, once the MFR of a resin was determined, it was possible to adjust the molding conditions to match that MFR and mold the resin. When determining molding conditions in advance based on the MFR value, the MFR value can be determined appropriately and may be increased as necessary.

[0106] The estimated MFR of recalled product A was 1.2 (g / 10 min), so the molding conditions of the injection molding machine were adjusted based on this estimated MFR. Specifically, the plasticization temperature was set to 270°C, the chamber temperature to 260°C, the nozzle temperature to 220°C, the primary pressure to 12 MPa, and the secondary pressure to 6 MPa. Here, the plasticization temperature is the temperature at which the resin melts, and the primary pressure is the injection pressure.

[0107] Using the above injection molding machine, a molded product was produced by molding market recalled product A under the adjusted molding conditions. The molded product was a good molded product without sink marks or burrs.

[0108] (Accuracy of estimated MFR) For the recovered resins B to K, resin molding was performed using the resin molding method of the above example. Then, for each resin (recovered resins B to K), ΔR1 / ΔR2 was calculated to estimate the MFR, and the MFR was also measured. The accuracy of the estimated MFR was then calculated. The results are shown in Table 1. As mentioned above, the accuracy of the estimation is expressed as the ratio of the estimated MFR to the measured MFR. The closer the accuracy of the estimation is to 100%, the better. If the absolute value of the difference from 100% is 30% or less, the resin is suitable for use in molding using the resin molding method of the present invention. In Table 1, B to K in the resin column are recovered resins B to K. The reflectance 1 (%) and reflectance 2 (%) of recovered resins B to K are also shown in Table 1. The visual color (resin color) of recovered resins B to K is also shown in Table 1.

[0109] Market Recycled Product B is a resin recovered from the used electrical parts market, and the resin type is R-PBT. Market Recycled Product C is a resin recovered from the used car market, and the resin type is R-PP. Market Recycled Product D is a resin recovered from the used car market, and the resin type is R-PP. Market Recycled Product E is a resin recovered from the used container packaging market, and the resin type is R-LDPE. R-LDPE stands for recycled low-density polyethylene. Market Recycled Product F is a resin recovered from the used container packaging market, and the resin type is R-LDPE. Market Recycled Product G is a resin recovered from the used container packaging market, and the resin type is R-PP. Market Recycled Product H is a resin recovered from the used electrical parts market, and the resin type is R-POM. Market Recycled Product I is a resin recovered from the used building materials market, and the resin type is R-POM. Market recovered product J is a resin recovered from used beverage containers on the market, and the type of resin is R-PET. Market recovered product K is a resin recovered from used fishing nets on the market, and the type of resin is R-PA.

[0110] Note that a correlation with MFR could not be obtained using only the electromagnetic wave intensity information (ΔR1) including the electromagnetic wave intensity of the molten resin. Furthermore, the absorption peak corresponding to the absorption peak Sm (see Figure 2) in the reflectance value without SNV conversion could not be correlated with MFR. Furthermore, a correlation between the absorption peak Sm in the "wavelength-SNV converted reflectance graph" and MFR could not be obtained.

[0111] Example 2 (2) Resin selection method The MFR was estimated by the physical property estimation step in the resin molding method of Example 1, the molding conditions were adjusted based on the estimated MFR, and a resin was selected to suit the obtained molding conditions.

[0112] Resin sorting was carried out on market recovered products A to K.

[0113] From the molding conditions obtained from the estimated MFR of each resin, recovered resins A, B, and K were selected as resins with the same molding conditions. Recovered resins C to J were selected as resins with different molding conditions. This revealed that recovered resins A, B, and K could be mixed and molded. [Industrial Applicability]

[0114] According to the present invention, it is possible to provide a resin molding method that can estimate specific physical properties of a resin whose physical properties are unknown in a simple manner, adjust molding conditions based on the estimated physical properties, and mold the resin under those molding conditions. [Explanation of symbols]

[0115] 1 test piece 2 Heat resistant stand 3 Slide plate 4 thermocouples 5 Heat-resistant tape 6 Temperature display 7 Heat source 8 light source 9 Camera S01 Physical property estimation process S02 Molding process M Graph M S Graph S

Claims

1. a physical property estimation step of irradiating a resin with electromagnetic waves including near-infrared rays, measuring the electromagnetic wave intensity of the electromagnetic waves reflected on the surface of the resin, and estimating the flowability of the resin based on electromagnetic wave intensity information including the electromagnetic wave intensity; a molding step of adjusting molding conditions based on the estimated flowability of the resin and molding the resin under the molding conditions; A resin molding method comprising the steps of:

2. The physical property estimation step The solid resin is heated to form a molten resin, and the electromagnetic wave intensity of the molten resin is measured; cooling the molten resin to form a solid resin, and measuring the electromagnetic wave intensity of the solid resin; The resin molding method according to claim 1 , further comprising the step of estimating the ease of flow of the resin based on the electromagnetic wave intensity information including the two obtained electromagnetic wave intensities.

3. When the solid resin is heated to form the molten resin, the heating is performed at a heating rate of 5 to 25°C / min, 3. The resin molding method according to claim 2, wherein the molten resin is cooled to form the solid resin at a cooling rate of 1 to 10° C. / min.

4. The physical property estimation step calculating the reflectance of each electromagnetic wave based on the electromagnetic wave intensities at the molten resin and the solid resin; The reflectance or the reflectance to which a transformation has been applied is used as reflectance data, In the reflectance data of the molten resin, two specific wavelengths are selected, and the reflectance data at the larger wavelength λa is designated as a and the reflectance data at the smaller wavelength λb is designated as b. ΔR1 is a value obtained by subtracting b from a, In the reflectance data of the solid resin, two specific wavelengths are selected, and the reflectance data at the larger wavelength λc is designated as c and the reflectance data at the smaller wavelength λd is designated as d. ΔR2 is a value obtained by subtracting d from c, Calculate ΔR1 / ΔR2, 3. The resin molding method according to claim 2, further comprising the step of estimating the ease of flow of the resin using ΔR1 / ΔR2 as the electromagnetic wave intensity information.

5. The solid resin is heated, and the temperature at which the resin changes from a solid state to a molten state is defined as T1°C. The electromagnetic wave intensity of the molten resin is measured in a temperature range of T1 to T1+10°C.

3. The resin molding method according to claim 2, wherein the electromagnetic wave intensity of the solid resin is measured in a temperature range of 20 to 40°C.

6. The physical property estimation step 5. The resin molding method according to claim 4, further comprising the step of estimating the ease of flow of the resin based on the electromagnetic wave intensity information using a calibration curve that correlates the value of ΔR1 / ΔR2 with the ease of flow of the resin.

7. The wavelength λa and the wavelength λc are wavelengths included in a wavelength range of 1585 to 1605 nm, 5. The resin molding method according to claim 4, wherein the wavelength λb and the wavelength λd are wavelengths included in the wavelength range of 1535 to 1550 nm.

8. 3. The resin molding method according to claim 1, wherein the estimated flowability of the resin is a melt mass flow rate.

9. the molding step is a step of molding the resin while adjusting the molding conditions, the adjusted molding conditions are molding conditions adjusted while acquiring the electromagnetic wave intensity information of the resin during molding; The resin molding method according to claim 1 or 2.

10. the molding step is a step of heating and molding the resin, 3. The resin molding method according to claim 1, wherein the molding conditions include a condition for heating the resin.

11. 3. The resin molding method according to claim 1, wherein the resin is a mixture of a plurality of resins.

12. 3. The resin molding method according to claim 1, wherein the resin is a recycled resin.

13. The resin molding method according to claim 1 or 2, wherein the physical property estimation step and the molding step are repeated a plurality of times.

14. irradiating a resin with electromagnetic waves including near-infrared rays, measuring the electromagnetic wave intensity of the electromagnetic waves reflected by the surface of the resin, and estimating the ease of flow of the resin based on electromagnetic wave intensity information including the electromagnetic wave intensity; A resin selection method in which molding conditions are adjusted based on the estimated flowability of the resin, and the resin is selected in accordance with the obtained molding conditions.

15. The resin selection method according to claim 14, wherein the resin is a recycled resin.

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