JP6089244B2 - Method for analyzing resin degradation process, and method for producing synthetic resin material and recycled resin material - Google Patents

Description

In the present invention, the deterioration state of the synthetic resin material and the recycled resin material is simply evaluated by a melt flow rate test, and based on this evaluation, an additive is added to the synthetic resin material and the recycled resin material to extend the life. The present invention relates to a resin material and a molded product using the resin material.

The degradation of the resin is classified into degradation caused by hydroperoxide and degradation derived from stable oxide generation. Deterioration progresses when the side chains and terminals of molecules excited by heat and light undergo degradation due to chemical reactions such as oxidation, or the main chain is cleaved. The deterioration of the resin also occurs during the molding process and during use, and is accelerated by various factors such as stress, temperature, oxygen, moisture, radiation, ozone, and chemicals. The deterioration state of the resin is confirmed by a decrease in molecular weight due to cleavage of the main chain or side chain, a decrease in strength associated therewith, a decrease in performance due to cross-linking, and a decrease in appearance. Measuring the molecular weight of the resin material is important in confirming degradation due to the main chain cleavage of the resin, but even with resins that can analyze the molecular weight, the mechanical strength does not decrease in proportion to the molecular weight. There is a characteristic that the strength sharply decreases when the molecular weight is reduced below the limit molecular weight of the resin material (Non-patent Document 1). On the other hand, olefin-based resins are hardly soluble in solvents in the first place, so it is difficult to measure molecular weight. The deterioration of the resin is complicated in this way, and the method for analyzing the state is complicated.

The analysis of the resin deterioration is performed by capturing a transient state in which oxidation occurs dynamically. On the other hand, statically, it is made by analyzing a resin in a state where oxidation or decomposition has occurred as a reaction product after being oxidized and capturing the state. In order to grasp the deterioration state of the resin and take appropriate measures for preventing the deterioration, a dynamic analysis method capable of grasping the transient state of the deterioration, that is, the deterioration process is particularly important.

As a dynamic analysis method, in general, when discussing the heat resistance of a resin material, a thermal analysis centering on thermogravimetry is performed. In this method, deterioration in a large-scale reaction temperature region accompanying main chain cleavage that causes gasification of the resin material is evaluated. On the other hand, with respect to the initial stage of oxidative degradation of side chains and resin ends that occur before the main chain is cleaved, luminescence is measured by oxidation when the resin is heated to estimate the degradation state (Patent Document 1, Non-Patent Document 1). Patent Document 2) has been proposed. Although these analytical methods are useful, thermogravimetry cannot measure minute weight changes due to initial oxidation, while the oxyluminescence method cannot quantitatively detect main chain cleavage as a luminescence phenomenon. It was. Against this background, the development of a simple analytical method for grasping the initial process of resin oxidative degradation, which is the initial resin degradation process, and the development of a method for simply evaluating the subsequent main chain scission process are desired. It was.

Japanese Patent Laid-Open No. 2002-195951

Plastics, Vol. 55, no. 4 November 18, 2012 Industry and Technology Federation Polymer Subcommittee Abstract p35

As described above, the problems related to the prior art are that there is no identical analysis method covering the initial process of oxidative degradation and the main chain scission process when discussing resin degradation, and furthermore, resin degradation based on this analytical method. Resin material and recycled resin material and / or resin molded product whose degradation process is controlled and / or suppressed based on evaluation of degradation process, and molded product appropriately containing recycled resin material are not provided It is.

The present invention has been made in view of the above points, and an object of the present invention is to provide an analysis method that covers the initial stage of oxidative degradation and the main chain scission process when discussing resin degradation. To provide a synthetic resin material and / or a resin molded article to which an additive for appropriately controlling and / or suppressing the deterioration process is added. It is to provide a recycled resin material whose control and / or deterioration state is grasped and / or a molded article appropriately containing the recycled resin material.

Means for Solving the Invention

Claim 1 of the present invention relates to a resin material and / or a resin that has an extended life by reducing the speed of the degradation process of the resin by adding an antioxidant for controlling and / or inhibiting the degradation process of the resin. It is a resin molded product using materials, and as a process of judging the deterioration process of resin,
A step of the activation energy of the resin degradation reaction rate constant degradation reaction is measured by a melt flow rate different at temperatures above the melting point of at least two points of the resin as the first step,
Determining whether the resin deterioration process includes an oxidation deterioration initial process as a second process,
The step of measuring the melt flow rate at at least two different temperatures above the melting point of the resin material as the first step includes performing at least one melt flow rate test as the first melt flow rate measurement step. Obtaining a melt flow rate value (first MFR value);
The resin material that has flowed out to obtain the first MFR value is a step of performing a melt flow rate test at least once as a second melt flow rate measurement step to obtain a melt flow rate value (second MFR value),
From the first MFR value, the second MFR value, and the melt flow rate measurement process number measured for each predetermined temperature, a degradation reaction rate constant k is calculated using Equation 1, and the degradation reaction rate constant k and each degradation reaction are calculated. It is a step of calculating the activation energy from Equation 2 from the temperature at which the rate constant k is measured ,
In the second step, the determination of whether the deterioration process of the resin includes an initial oxidation deterioration process is performed by comparing the first MFR value and the second MFR value.
When the first MFR value is larger than the second MFR value and the activation energy value calculated in the first step is lower than 80 kJ / mol, the initial oxidation deterioration process is dominant in the deterioration process of the resin. Is determined to be
When the first MFR value is smaller than the second MFR value and the activation energy value is 80 kJ / mol or more, the degradation process of the resin is not dominant even if it includes the initial oxidation degradation process, and the main chain When it is determined that the main chain cleavage process involving cleavage is dominant and the difference between the first MFR value and the second MFR value is within 0.4%, in the degradation process of the resin, the oxidation degradation initial stage Even if the process is included, it is determined that the main chain scission process may occur without being dominant. Therefore, the first MFR value and the second MFR value are compared again by raising the measurement temperature and measuring the first MFR value and the second MFR value again. And determining whether the resin includes an initial stage of oxidative degradation,
By adding an antioxidant for controlling and / or inhibiting the deterioration process of the resin , the speed of the deterioration process of the resin is reduced to increase the life of the resin material and / or a molded article using the resin material. is there.

(Formula 1) Ln ((first MFR value) ÷ (second MFR value)) / ((number of MFR measurement steps) −1)
= K
(Formula 2) Ln (k) = Ln (frequency factor) − (activation energy) / (8.314 J / molK × (temperature))

As described above, the conventional has been performed using different analytical techniques, respectively to evaluate the oxidative degradation early stage and the main chain cleavage process when discussing the degradation of the resin, according to claim 1 of the present invention, Based on the degradation process of the synthetic resin, the reaction process, reaction rate, and activation energy that caused the degradation of the synthetic resin were clarified by measuring the melt flow rate of the synthetic resin. By adding an additive for preventing deterioration to the resin, it is possible to effectively extend the life of the resin by controlling and / or suppressing the deterioration of the resin. Also, by measuring the melt flow rate, it is possible to determine the deterioration state of the resin used or molded, and to determine the mixing ratio of the recycled resin material to the molded product based on the determination result This makes it possible to appropriately manage and use recycled resin materials.

It is a figure showing the degradation process of resin analyzed by the analysis method of this invention. It is a figure of the melt flow rate value and the weight average molecular weight with respect to the frequency | count of repetition molding (number of times of recycling) when the mixed resin of polystyrene (PS) and polyphenylene ether (PPE) is repeatedly injection molded. It is the figure which plotted the weight average molecular weight with respect to the melt flow rate value of the polystyrene-polyphenylene ether mixed resin which performed injection molding repeatedly. It is the figure which plotted Ln (k) with respect to the reciprocal of temperature based on Formula 2. It is the figure which showed the melt flow rate value with respect to the melt flow rate measurement frequency of low density polyethylene. It is a flowchart for determining the resin deterioration state of this invention. It is a flowchart for determining the deterioration state of the recycled resin material of this invention. Tables of melt flow rate values of thermoplastic resins implemented in Examples 1 to 3 and Examples 5, 6, and 8, degradation processes evaluated from melt flow rate values, reaction rate constants, and activation energies is there. It is a melt flow rate value and a weight average molecular weight for each repeated injection molding of a mixed resin of polystyrene (PS) and polyphenylene ether (PPE).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As an example of the analysis according to the first embodiment of the present invention, low-density polyethylene (LDPE, manufactured by Aldrich) pellets were used, and a post-drying melt flow rate test was performed. A melt flow rate automation system (manufactured by Toyo Seiki Co., Ltd., fully automated system 520) was used for the melt flow rate test. The test conditions were a temperature of 210 ° C., 230 ° C., 250 ° C., a load of 5.0 kg, and a temperature holding time of 300 seconds. The results are shown in FIG. Here, the number of repetitions is the number of times that the melt flow rate test was repeatedly performed on the same resin material. The melt flow rate value of the LDPE pellet was 6.69 g / 10 minutes (may be expressed as min) at a repetition number of 1 (temperature holding time of 300 seconds), but the number of repetitions was 2 (temperature holding time of 600 seconds). At 6.13 g / 10 min, and further decreased to 5.55 g / 10 min at 3 repetitions (temperature treatment time 900 seconds). As a result of Example 1, since the first MFR value was larger than the second MFR value for the LDPE resin, it was determined that the initial oxidation deterioration process was dominant in the deterioration process of the resin material. If deterioration due to main chain breakage has occurred, an increase in melt flow rate value should be confirmed as in Example 2 and Example 3 described later. If the observed decrease in the melt flow rate value indicates an increase in molecular weight, it is considered that some kind of reaction has occurred in the resin during the initial stage of oxidative degradation due to heat treatment. In Example 1, the degradation reaction rate constant k in the initial stage of oxidative degradation of LDPE resin was 0.0981 / time at 210 ° C., 0.1557 / time at 230 ° C., 0.3484 / time at 250 ° C., and the inverse of temperature. Ln (k) was plotted as shown in FIG. 4, and the activation energy was determined to be 66 kJ / mol (also referred to as mol) from the slope of the straight line. Further, as shown in FIG. 5, when the number of temperature repetitions was increased at 230 ° C., an increase in MFR value was confirmed, and it was confirmed that a main chain scission process following the initial process of oxidative degradation occurred. The analysis result of Example 1 is shown in FIG. In Example 1, the degradation process of the resin was evaluated using the flowchart shown in FIG.

As an example of analysis according to the second embodiment of the present invention, analysis of degradation process and degradation of polymethyl methacrylate (PMMA) in which the main chain is similar to polyethylene and oxygen is bonded to carbon of the side chain. The reaction rate constant and the activation energy of the degradation reaction were determined. Using the dried pellets, the melt flow rate test was repeatedly performed under the conditions of a temperature of 230 ° C., a load of 5.0 kg, and a temperature holding time of 300 seconds. A melt flow rate automation system (manufactured by Toyo Seiki Co., Ltd., fully automated system 520) was used for the melt flow rate test. The results are shown in FIG. The measured MFR value was 9.04 g / 10 minutes at a repetition number 1 (temperature holding time 300 seconds), but decreased to 9.00 g / 10 minutes at a repetition number 2 (temperature holding time 600 seconds). When the number of repetitions was 3 (temperature holding time: 900 seconds), it further decreased to 8.96 g / 10 minutes. Since the deterioration reaction process at this time is a case where the first MFR value is larger than the second MFR value, it was determined that the initial stage of oxidation deterioration was dominant in the deterioration process of the resin material. Degradation rate constant of the oxidation deterioration initial stage of temperature 230 ° C. was set to 0.0044 / dose. In addition, when the experiments were performed under the same conditions except that the temperature was 240 ° C., the first MFR value was still larger than the second MFR value. It was determined to be dominant. Further, degradation rate constant of the oxidation deterioration initial stage of temperature 240 ° C. was set to 0.0058 / dose. In addition, when the experiment was performed under the same conditions except that the temperature was 250 ° C., the first MFR value was smaller than the second MFR value, and therefore the deterioration process of the resin material included an initial stage of oxidation deterioration. However, it was judged that the main chain cutting process accompanied by main chain breakage was dominant. Further, the degradation reaction rate constant of the main chain cleavage process accompanied by main chain cleavage at 250 ° C. was set to 0.0312 / times. From the above, for the PMMA, the activation energy of the oxidative degradation initial process from 230 ° C. to 240 ° C. was calculated to 59kJ / mol. The analysis result of Example 2 is shown in FIG. In Example 2 , the degradation process of the resin was evaluated using the flowchart shown in FIG. As described above, in the method for analyzing the deterioration process of the resin of the present invention, it was confirmed that even if the same resin is used, different decomposition processes occur due to temperature differences.

As an example of the analysis according to the third embodiment of the present invention, the analysis of the degradation process, the rate of the degradation reaction, and the activation energy of the degradation reaction were obtained for polyoxymethylene (POM) containing oxygen in the main chain. Using the dried pellets, the melt flow rate test was repeatedly performed under the conditions of a temperature of 200 ° C., a load of 2.16 kg, and a temperature holding time of 300 seconds. A melt flow rate automation system (manufactured by Toyo Seiki Co., Ltd., fully automated system 520) was used for the melt flow rate test. The results are shown in FIG. The measured MFR value was 20.96 g / 10 minutes at the number of repetitions 1 (temperature holding time 300 seconds), but increased to 21.31 g / 10 minutes at the number of repetitions 2 (temperature holding time 600 seconds), When the number of repetitions was 3 (temperature holding time 900 seconds), the number further increased to 21.94 g / 10 minutes. Since the first MFR value is smaller than the second MFR value, the degradation process of the resin material is not dominant even if it includes the initial oxidation degradation process, and it is determined that the degradation process involving main chain scission is dominant. It was. Moreover, the rate constant of the main chain cutting process accompanied by main chain cleavage at 200 ° C. was calculated to be 0.0170 / time. In addition, when the experiment was performed under the same conditions except that the temperature was 210 ° C., the first MFR value was smaller than the second MFR value, so that the deterioration process of the resin material included the initial stage of oxidation deterioration. However, it was judged that the degradation process accompanied by the main chain breakage was dominant. Moreover, the rate constant of the main chain cutting process accompanied by main chain cleavage at 210 ° C. was calculated to be 0.0619 / time. In addition, when the experiment was performed under the same conditions except that the temperature was 230 ° C., the first MFR value was smaller than the second MFR value, and therefore the initial deterioration process of the resin material was included in the deterioration process of the resin material. However, it was judged that the degradation process accompanied by the main chain breakage was dominant. Further, the rate constant of the main chain cleavage process accompanied by main chain cleavage at 230 ° C. was calculated to be 0.1001 / time. From the above, for POM, the activation energy accompanying main chain cleavage from 200 ° C. to 230 ° C. was calculated to be 108 kJ / mol . The analysis result of Example 3 is shown in FIG. In Example 3 , the degradation process of the resin was evaluated using the flowchart shown in FIG.

As the fourth embodiment of the present invention, the deterioration process of the resin was analyzed based on the first to third embodiments of the present invention. The results are shown in FIG. From the first embodiment, the degradation process of LDPE containing no oxygen in both the side chain and the main chain was observed as an initial stage of oxidative degradation in which the side chain and terminal of the resin are oxidized. Moreover, as for the degradation process of PMMA containing oxygen in the side chain, a part of the initial oxidation degradation process was observed, but the main chain cleavage process was also observed. On the other hand, the degradation process of POM containing oxygen in the main chain was observed to be dominated by the main chain cleavage process. Thus, as in the present invention, repeatedly measuring the melt flow rate of the resin is a simple analytical method for grasping the initial process of oxidative degradation of the resin, which is the initial process of resin degradation, and the subsequent main chain cleavage process. It was shown to be useful as a simple evaluation method.

As an example of analysis according to the fifth embodiment of the present invention and prevention of deterioration process of the resin, among the analysis conditions according to the first embodiment, as an additive to LDPE, an antioxidant Irganox 1010 (registered trademark) The melt flow rate value of LDPE was measured under the same conditions except that was added at 1 wt% with respect to LDPE. The melt flow rate value of LDPE with an additive at a temperature of 210 ° C. was 6.60 g / 10 min at 1 repetition (temperature holding time 300 seconds), but at 2 repetitions (temperature holding time 600 seconds). It decreased to 6.48 g / 10 min, and further decreased to 6.29 g / 10 min at 3 repetitions (temperature treatment time: 900 seconds). For the LDPE resin of Example 5, since the first MFR value is larger than the second MFR value, it was determined that the initial stage of oxidation deterioration was dominant in the deterioration process of the resin material. Moreover, the degradation process was evaluated as an initial stage of oxidation degradation for LDPE to which an additive was added even at 230 ° C. and 250 ° C. In Example 5, the degradation reaction rate constant in the initial stage of oxidative degradation of the LDPE resin to which the additive was added was 0.0183 / time at 210 ° C., 0.0250 / time at 230 ° C., and 0.0549 / time at 250 ° C. The activation energy was found to be 58 kJ / mol . Compared to LDPE without added additives was carried out in Example 1, the additive LDPE in oxidation deterioration initial stage was added conducted in Example 5, 18% at 210 ° C., 16% at 230 ° C., 250 ° C. It was confirmed that the resin life could be extended to 16%. The results analyzed in Example 5 are shown in FIG. In Example 5 , the degradation process of the resin was evaluated using the flowchart shown in FIG.

As an example of analysis according to the sixth embodiment of the present invention and prevention of deterioration process of the resin, among the analysis conditions according to the second embodiment, as an additive to PMMA, an antioxidant Irganox 1010 (registered trademark) The PMMA melt flow rate value was measured under the same conditions except that 1 wt% of PMMA was added to PMMA. The melt flow rate value of PMMA containing an additive at a temperature of 250 ° C. was 31.06 g / 10 min at 1 repetition (temperature holding time 300 seconds), but at 2 repetitions (temperature holding time 600 seconds). It decreased to 28.71 g / 10 minutes, and further decreased to 28.88 g / 10 minutes after 3 repetitions (temperature treatment time: 900 seconds). For PMMA of Example 6, since the first MFR value was greater than the second MFR value, it was determined that the initial stage of oxidation deterioration was dominant in the deterioration process of the resin material. On the other hand, in PMMA with no additive added in Example 2, at 250 ° C., the degradation process of the resin material is not dominant even if it includes the initial stage of oxidation degradation, and the degradation process accompanied by the cleavage of the main chain occurs. Since it was determined to be dominant, it was confirmed that the resin life could be extended in PMMA with the additive added in Example 6 added. The results analyzed in Example 6 are shown in FIG. In Example 6 , the degradation process of the resin was evaluated using the flowchart shown in FIG.

As an example of analysis according to the seventh embodiment of the present invention, a melt flow rate test and a molecular weight distribution measurement were repeatedly performed for each injection molding of a mixed resin injection molded product of polystyrene (PS) and polyphenylene ether (PPE). . In the injection molding, a dumbbell-shaped tensile test piece was prepared using a desktop injection molding machine. A melt flow rate automation system (manufactured by Toyo Seiki Co., Ltd., fully automated system 520) was used for the melt flow rate test, and a molecular weight distribution measurement system (D5280 LCS M-PDA, manufactured by Shimadzu Corporation) was used for the molecular weight distribution measurement. 9 and 2 show the melt flow rate value and the weight average molecular weight for each repeated injection molding. As the number of repeated injection moldings increased, the melt flow rate value increased. When the melt flow rate value is repeatedly measured for each number of repeated injection moldings, the PS-PPE mixed resin of Example 7 has the first MFR value <the second MFR value <the third MFR value, so the deterioration state of the resin material is It was determined that the main chain was broken. Lowering of the weight average molecular weight is believed to be due to the main chain scission of the resin, since the weight average molecular weight of the resin according to the injection molding count is increased is reduced, deterioration state of this resin material with a cutting of the main chain It was confirmed to affirm that it is. Moreover, as shown in FIG. 3, the melt flow rate value increased as the weight average molecular weight decreased. From these facts, it was confirmed that the increase in the melt flow rate value with respect to the number of repeated injection moldings was able to observe a decrease in the molecular weight due to the main chain cleavage of the resin. In Example 7 , evaluation of the deterioration process of the resin was performed using the flowchart shown in FIG.

As an example of the analysis according to the eighth embodiment of the present invention, a plot of the weight average molecular weight with respect to the melt flow rate value of the PS-PPE mixed resin measured in the analysis according to the seventh embodiment is shown in FIG. This result shows that there is a correlation between the melt flow rate value and the weight average molecular weight, and the slope decreases as the number of repeated injection moldings increases. PPE is a typical engineering plastic having a high softening point and excellent mechanical and electrical characteristics, but has poor moldability due to its high melting temperature. Therefore, PS-PPE mixed resin has improved melt flow characteristics by blending PS compatible with PPE into a mixed resin. The result of measuring the melt flow rate value of only PS is shown in FIG. In PS, an increase in melt flow rate value was confirmed even when the number of repeated measurements was small. From these facts, it is judged that the deterioration at the stage where the number of repeated measurements in the PS-PPE mixed resin is small is mainly due to the decomposition of PS. Thus, it was shown that the deterioration process and the deterioration reaction rate accompanied by the main chain breakage can be evaluated for each mixed resin by repeatedly performing the melt flow rate test on the mixed resin. The activation energy was calculated as 83 kJ / mol. The activation energy of the deterioration reaction accompanying the main chain cleavage process obtained in Example 3 and Example 8 described above is 80 kJ / mol or more, and the oxidation obtained in Example 1, Example 2 and Example 5 It was confirmed that the activation energy of the degradation reaction determined to be the initial degradation process was less than 80 kJ / mol.

As an example of analysis according to the ninth embodiment of the present invention, LDPE heat-treated at 270 ° C. for 30 minutes and light from a xenon lamp having a wavelength distribution similar to sunlight were irradiated for about 6 months in terms of outdoor conversion. Three types of degraded resins, LDPE and PMMA, were prepared as recycled resin materials. The degradation state of these recycled resin materials is such that the first MFR value <the second MFR value <the third MFR value in the LDPE degraded by the xenon lamp light according to the evaluation method of the degradation state of the resin of the present invention. It was determined that the deterioration state of the material was a state in which the main chain was broken. LDPE heat-treated at 270 ° C. for 30 minutes had the first MFR value> the second MFR value <the third MFR value. Therefore, although the degradation state of the recycled resin material is in the initial stage of oxidative degradation, the main chain can be broken. It was determined. In the PMMA deteriorated by the xenon lamp light, since the first MFR value> the second MFR value> the third MFR value, the deterioration state of the recycled resin material was determined to be the initial stage of oxidation deterioration. In Example 9, the deterioration process of the resin was evaluated using the flowchart shown in FIG.

The LDPE deteriorated by the xenon lamp light prepared in Example 9 was mixed with undegraded LDPE, and 0 wt%, 30 wt%, 50 wt%, 80 wt%, and 100 wt% (in this case, all deteriorated) The resin material contained at a ratio of (using LDPE) was prepared. A dumbbell-shaped tensile test piece was prepared as an LDPE injection-molded product using a desktop injection molding machine, and a tensile test was performed. When the tensile strength of a test piece having a recycled resin material ratio of 0 wt% was taken as 100, a tensile strength of 95 was obtained at 30 wt%, 80 at 80 wt%, 60 at 80 wt%, and 50 at 100 wt%. From these results, it was confirmed that, with respect to the recycled resin in a state in which the main chain cleavage process occurs, by setting the mixing ratio to 1 to 30 wt% or less, good results can be obtained in terms of strength. Further, when the mixing amount is more than 30 wt%, the strength is reduced, and it has been confirmed that the application is limited. However, it was confirmed that the tensile strength was improved by adding an antioxidant .

The LDPE produced in Example 9 and deteriorated by heat treatment at 270 ° C. for 30 minutes was mixed with undegraded LDPE, and 0 wt%, 30 wt%, 50 wt%, 80 wt%, and 100 wt% (in this case, all A resin material containing a ratio of (using deteriorated LDPE) was prepared. A dumbbell-shaped tensile test piece was prepared as an LDPE injection-molded product, and a tensile test was performed. When the tensile strength of the 0 wt% test piece was 100%, the tensile strength of 98 was obtained at 30 wt%, 95 at 50 wt%, 90 at 80 wt%, and 80 at 100 wt%. From these results, when the deterioration state of the resin material is a state in which the main chain cutting process that can cause the main chain to be broken is in the initial stage of oxidation deterioration, the mixing ratio is set to 1 wt% or more and 80 wt% or less. It was confirmed that good results were obtained. Further, when the mixing amount is more than 80 wt%, the strength is reduced, and it has been confirmed that the application is limited. However, it was confirmed that the tensile strength was improved by adding the additive.

The PMMA deteriorated by the xenon lamp light prepared in Example 9 was mixed with undegraded PMMA, 0 wt%, 30 wt%, 50 wt%, 80 wt%, and 100 wt% (in this case, all deteriorated) A resin material containing PMMA was used. As an injection molded product of PMMA, a dumbbell-shaped tensile test piece was prepared and a tensile test was performed. When the tensile strength of a test piece having a recycled resin material ratio of 0 wt% was taken as 100, 99 tensile strength was obtained at 30 wt%, 99 at 50 wt%, 98 at 80 wt%, and 96 tensile strength at 100 wt%. From these results, it was confirmed that when the deterioration state of the resin material was determined to be the initial stage of oxidation deterioration, good results were obtained at a mixing ratio of 1 wt% to 100 wt%.

Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

In the prior art, it was necessary to use a plurality of analytical methods to cover the initial stage of oxidation degradation and the main chain scission process in order to discuss resin degradation. According to the present invention, by performing a melt flow rate test to measure the flowability of the resin, it is possible to obtain the deterioration process of the resin covering the initial stage of oxidation deterioration and the main chain cutting process, its reaction rate constant, and the activation energy of the reaction. It has become possible. According to the present invention, it is possible to evaluate the recyclability and weather resistance of resin materials that can be expected to expand in the future at a lower cost than conventional ones. Moreover, since the operation is simple and the standardization of work is easy, the industrial applicability is great.

Claims (1)

By adding an antioxidant for controlling and / or suppressing the deterioration process of the resin, the resin material that has reduced the speed of the deterioration process of the resin to increase the service life and / or the resin molded product using the resin material As a process of judging the deterioration process of the resin,
A step of the activation energy of the resin degradation reaction rate constant degradation reaction is measured by a melt flow rate different at temperatures above the melting point of at least two points of the resin as the first step,
Determining whether the resin deterioration process includes an oxidation deterioration initial process as a second process,
The step of measuring the melt flow rate at at least two different temperatures above the melting point of the resin material as the first step includes performing at least one melt flow rate test as the first melt flow rate measurement step. Obtaining a melt flow rate value (first MFR value);
The resin material that has flowed out to obtain the first MFR value is a step of performing a melt flow rate test at least once as a second melt flow rate measurement step to obtain a melt flow rate value (second MFR value),
From the first MFR value, the second MFR value, and the melt flow rate measurement process number measured for each predetermined temperature, a degradation reaction rate constant k is calculated using Equation 1, and the degradation reaction rate constant k and each degradation reaction are calculated. It is a step of calculating the activation energy from Equation 2 from the temperature at which the rate constant k is measured ,
In the second step, the determination of whether the deterioration process of the resin includes an initial oxidation deterioration process is performed by comparing the first MFR value and the second MFR value.
When the first MFR value is larger than the second MFR value and the activation energy value calculated in the first step is lower than 80 kJ / mol, the initial oxidation deterioration process is dominant in the deterioration process of the resin. Is determined to be
When the first MFR value is smaller than the second MFR value and the activation energy value is 80 kJ / mol or more, the degradation process of the resin is not dominant even if it includes the initial oxidation degradation process, and the main chain When it is determined that the main chain cleavage process involving cleavage is dominant and the difference between the first MFR value and the second MFR value is within 0.4%, in the degradation process of the resin, the oxidation degradation initial stage Even if the process is included, it is determined that the main chain scission process may occur without being dominant. Therefore, the first MFR value and the second MFR value are compared again by raising the measurement temperature and measuring the first MFR value and the second MFR value again. And determining whether the resin includes an initial stage of oxidative degradation,
A resin material and a molded article using the resin material, which has an increased life by reducing the speed of the deterioration process of the resin by adding an antioxidant for controlling and / or inhibiting the deterioration process of the resin.

(Formula 1) Ln ((first MFR value) ÷ (second MFR value)) / ((number of MFR measurement steps) −1)
= K
(Formula 2) Ln (k) = Ln (frequency factor) − (activation energy) / (8.314 J / molK × (temperature))