JP5811337B2 - 2-pyrrolidone polymer or copolymer with modified physical properties - Google Patents

Description

  The present invention relates to a polymer or copolymer of 2-pyrrolidone having modified physical properties, and a molded article containing the polymer or copolymer. Furthermore, the present invention relates to a method for increasing the thermal decomposition temperature of a 2-pyrrolidone polymer or copolymer.

  A characteristic of polyamide 4 (hereinafter also referred to as PA4) is that it can be synthesized from biomass. That is, the raw material monomer (2-pyrrolidone) can be obtained via γ-aminobutyric acid obtained by decarboxylating glutamic acid produced by fermentation of biomass (glucose) and industrially produced. Next, since polyamide 4 has a polymer chain structure with a short methylene chain length, hydrogen bonding between molecules is strengthened, and it has excellent thermal and mechanical properties. In addition, polyamide 4 is the only polyamide among which biodegradation is caused by microorganisms in the natural environment such as activated sludge, seawater, and soil. On the other hand, since the initiator is combined by the polymerization mechanism to generate a polymerization growth species, the polyamide 4 can be easily designed as a polymer.

  Polyamide 4 is a ring-opening polymerization of 2-pyrrolidone by an activated monomer mechanism by William O. Ney et al. In 1956 using potassium metal as a basic catalyst and an acyl group-containing compound as an activator. For the first time (Patent Document 1). Based on this method, new catalyst system, polymerization method, copolymerization with ε-caprolactam, etc. for the purpose of intermittent high molecular weight, polydispersity control, and simplification of production process from 1950s to 1990s Has been developed (Non-Patent Documents 1-5). In general, linear polyamide 4 was industrially produced as a general-purpose material, and the goal was to produce fibers and films by economically advantageous melt molding. Among these studies, there were examples of technological development that enabled melt spinning, but there were problems due to problems in strength and difficulty in molding, and practical application was abandoned.

  In order to solve the above problems, Patent Document 2 has a special structure including a structure derived from a carboxylic acid compound by polymerizing 2-pyrrolidone using a basic polymerization catalyst and a carboxylic acid compound. It has been reported that a 2-pyrrolidone polymer can be produced, and thereby various physical properties such as thermal stability and moldability of the 2-pyrrolidone polymer can be controlled and improved.

  Further, the polyamide 4 has a problem that molding and spinning are difficult because the melting point and the thermal decomposition temperature are close to each other. Thermal decomposition does not proceed by hydrolysis reaction but proceeds by generation of five-membered lactam by thermal cyclization reaction. As a solution to the problem, there is a report on a technique of lowering the melting point by copolymerization and molding at a lower temperature.

  For example, in Patent Document 3, in the polymerization of 2-pyrrolidone, a basic polymerization catalyst and an initiator having a branched structure of two or more branches are used for copolymerization with ε-caprolactam to obtain a polymer chain structure It has been reported that physical properties (mechanical properties and thermal properties) can be modified by controlling the polymer chain composition.

US Patent 2,739,959 JP 2002-265596 A JP 2009-155608 JP

Chuchma, F. et al: Polymer, 24, 1491-1494 (1983) Kobayashi, F. et al: Journal of Polymer Science: Part A, 1, 111-123 (1963) Barzakay, S. et al: Journal of Polymer Science: Part A-1, 4, 2211-2218 (1966) Barzakay, S. et al: Journal of Polymer Science: Part A-1, 5, 965-974 (1967) Tani, H. et al: Journal of Polymer Science: Part A-1, 4, 301-318 (1966)

  However, the melting point drop sacrifices the excellent heat-resistant property of polyamide 4. Therefore, there is a demand for the development of a method for separating the molding temperature from the molding temperature by lowering the melting point and separating the molding temperature from the molding temperature by increasing the thermal decomposition temperature through thermal stabilization.

  Therefore, an object of the present invention is to provide a polymer or copolymer of 2-pyrrolidone having an increased thermal decomposition temperature, and a molded product containing the polymer or copolymer. Furthermore, an object of the present invention is to provide a method for increasing the thermal decomposition temperature of a 2-pyrrolidone polymer or copolymer.

  The present inventors have obtained the knowledge that the thermal decomposition temperature of polyamide 4 can be increased by treating polyamide 4 with carbodiimide, and the above object can be achieved. Until now, for example, polylactic acid and polyamide have been treated with carbodiimide for the purpose of increasing hydrolysis resistance and the like (for example, JP-A-9-328609 and JP-A-2006-176597). (Patent Publication No. 2011-105822, International Publication No. 2009/054312), the use of carbodiimide for thermal stabilization of a polymer that is converted into a cyclic monomer by thermal decomposition, and the thermal decomposition temperature of the polymer was increased. The present invention is the first.

  The present invention has been completed based on these findings, and has been completed. The following 2-pyrrolidone polymer or copolymer, molded article containing the polymer or copolymer, and thermal decomposition temperature are determined. It provides a method for raising it.

(I) 2-pyrrolidone polymer or copolymer
(I-1) A polymer or copolymer of 2-pyrrolidone treated with carbodiimide.
(I-2) The polymer or copolymer according to (I-1), wherein the carbodiimide is N, N′-dicyclohexylcarbodiimide.
(I-3) The polymer or copolymer according to (I-1) or (I-2), which has a linear or branched structure.
(I-4) The copolymer according to any one of (I-1) to (I-3), which is a copolymer with lactams.
(I-5) The copolymer according to (I-4), wherein the lactam is ε-caprolactam.
(I-6) The copolymer according to any one of (I-1) to (I-3), which is a copolymer with a lactone.
(I-7) The copolymer according to (I-6), wherein the lactone is ε-caprolactone.

(II) Molded product
(II-1) A molded article comprising the polymer or copolymer according to any one of (I-1) to (I-7).

(III) Method of increasing the thermal decomposition temperature
(III-1) A method for increasing the thermal decomposition temperature of a 2-pyrrolidone polymer or copolymer, which comprises treating a 2-pyrrolidone polymer or copolymer with carbodiimide.
(III-2) The method according to (III-1), wherein the carbodiimide is N, N′-dicyclohexylcarbodiimide.

(IV) Method for producing 2-pyrrolidone polymer or copolymer
(IV-1) A process for producing a 2-pyrrolidone polymer or copolymer having an increased thermal decomposition temperature, which comprises reacting a 2-pyrrolidone polymer or copolymer with carbodiimide.
(IV-2) The method according to (IV-1), wherein the carbodiimide is N, N′-dicyclohexylcarbodiimide.
(IV-3) The method according to (IV-1) or (IV-2), wherein the polymer or copolymer has a linear or branched structure.
(IV-4) The method according to any one of (IV-1) to (IV-3), wherein the copolymer is a copolymer with lactams.
(IV-5) The method according to (IV-4), wherein the lactam is ε-caprolactam.
(IV-6) The method according to any one of (IV-1) to (IV-3), wherein the copolymer is a copolymer with a lactone.
(IV-7) The method according to (IV-6), wherein the lactam is ε-caprolactone.

  The polymer or copolymer of 2-pyrrolidone treated with the carbodiimide of the present invention has an increased thermal decomposition temperature, and the melting point and the thermal decomposition temperature are maintained while maintaining the excellent heat resistance property of polyamide 4. It has the excellent property of being separated. As a result, a 2-pyrrolidone polymer or copolymer can be easily molded.

  Furthermore, since the 2-pyrrolidone polymer or copolymer of the present invention is treated with carbodiimide, the recovery rate of 2-pyrrolidone monomer is improved, that is, the chemical recyclability is improved.

3 is a graph showing DTG of polyamide 4 in Test Example 1. 6 is a graph showing DTG of polyamide 4 in Test Example 2. 6 is a graph showing DTG of polyamide 4 in Test Example 3. 6 is a graph showing DTG of polyamide 4 in Test Example 4. 6 is a graph showing a TG curve of DCC-treated copolyesteramide in Test Example 5. FIG. 6 is a graph showing a DTG curve of DCC-treated copolyesteramide in Test Example 5. FIG. 6 is a graph showing a DSC curve of DCC-treated copolyesteramide in Test Example 5. FIG. It is a graph which shows the DTA curve at the time of making DCC or DIC react with the polyamide 4 in Test Example 6 without a solvent (direct mixing). It is a graph which shows the DTA curve at the time of making DIC react with the copolyesteramide in Test Example 6 without a solvent (homogenization process). It is a graph which shows the DTA curve at the time of making DCC react with the copolyesteramide in Test Example 6 without a solvent (homogenization process).

  Hereinafter, the present invention will be described in detail.

  The 2-pyrrolidone polymer or copolymer of the present invention is characterized by being treated with carbodiimide.

  The method for increasing the thermal decomposition temperature of the 2-pyrrolidone polymer or copolymer of the present invention is characterized in that the 2-pyrrolidone polymer or copolymer is treated with carbodiimide.

  Thus, by treating the 2-pyrrolidone polymer or copolymer with carbodiimide, the thermal decomposition temperature can be increased, and while maintaining the excellent heat-resistant properties of polyamide 4, the melting point and heat The decomposition temperature can be separated. Furthermore, by treating the 2-pyrrolidone polymer or copolymer with carbodiimide, the recovery rate of 2-pyrrolidone monomer after thermal decomposition can be improved, that is, the chemical recyclability can be improved.

  The 2-pyrrolidone polymer (polyamide 4 or nylon 4) used in the present invention can be produced according to a conventional method. The copolymer of 2-pyrrolidone is not particularly limited as long as the effects of the present invention can be obtained. For example, a copolymer of 2-pyrrolidone and lactams such as ε-caprolactam or 2-pyrrolidone and ε- Examples thereof include copolymers with lactones such as caprolactone. Of these copolymers, copolyamides can be produced according to the description in JP-A-2009-155608, and copolyesteramides are mixed with 2-pyrrolidone and ε-caprolactone, and then a basic initiator such as n-butyllithium. It can be synthesized by adding an agent (0.2 to 1.6 mol% with respect to both monomers) and reacting at room temperature to 50 ° C.

  The thermal decomposition temperature of the 2-pyrrolidone polymer or copolymer treated with the carbodiimide of the present invention is preferably 10 ° C or higher, more preferably 20 to 30 ° C. The thermal decomposition temperature can be determined by thermogravimetry.

  The carbodiimide in the present invention is not particularly limited as long as it can raise the thermal decomposition temperature by treating a polymer or copolymer of 2-pyrrolidone. For example, N, N′— Dicyclohexylcarbodiimide (DCC), 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide and its salts, dimethylcarbodiimide, diisopropylcarbodiimide (DIC), diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, bis (2,6 -Diisopropylphenyl) carbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β-naphthylcarbodiimide, aliphatic polycarbodiimide (for example, carbodilite manufactured by Nisshinbo Chemical Co., Ltd., having an isocyanate terminal) and the like. The carbodiimide is preferably N, N′-dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide and a salt thereof, and particularly preferably N, N′-dicyclohexylcarbodiimide.

  The 2-pyrrolidone polymer or copolymer of the present invention can be produced by reacting a 2-pyrrolidone polymer or copolymer with carbodiimide. By this reaction, carbodiimide is bonded to the carboxylic acid terminal of the 2-pyrrolidone polymer. The amount of the carbodiimide used is preferably 1 to 10 wt%, more preferably 3 to 7 wt% with respect to the 2-pyrrolidone polymer or copolymer. In the reaction, compounds other than carbodiimide may be added within a range in which the effects of the present invention can be obtained. Examples of such compounds include 1-hydroxybenzotriazole (HOBt). The reaction rate can be improved by adding HOBt.

  In the reaction with carbodiimide, a solvent having a solubility in polyamide 4 such as 2,2,2-trifluoroethanol can be used. In the reaction, the temperature condition is about 50 to 160 ° C., preferably about 70 to 100 ° C., and the reaction time is about 0.5 to 3 hours, preferably about 0.7 to 2 hours. Further, after the heat treatment is performed once, an additional heat treatment may be performed such that the material is heated again (for example, near the melting point) and rapidly cooled. Even without solvent, carbodiimide can be reacted, and heat stabilization effect can be achieved by reacting for a long time at high temperature after homogenizing the carbodiimide as an alcohol solution such as methanol, then impregnating the resin and distilling off the solvent. Is obtained. In the case where the homogenization treatment with an alcohol solution or the like is not performed, a certain effect on thermal stabilization can be obtained by directly mixing a large amount of carbodiimide.

  The 2-pyrrolidone polymer used in the present invention may have a linear or branched structure. By introducing such a branched structure, physical properties (tensile strength) are improved. A polymer of 2-pyrrolidone having a branched structure can be synthesized according to the description in Japanese Patent No. 3453600.

  The 2-pyrrolidone copolymer used in the present invention may also be a 2-pyrrolidone copolymer having a linear or branched structure, preferably 2-pyrrolidone having a linear or branched structure and ε. -Copolymer of caprolactam or ε-caprolactone. By using a copolymer having a branched structure, the melting point can be lowered and flexibility can be imparted. A copolymer of 2-pyrrolidone and ε-caprolactam having a branched structure can be synthesized by the method described above, and a copolymer of 2-pyrrolidone and ε-caprolactone can be synthesized using an initiator (multiple Can be synthesized by using an alkoxide of a monohydric alcohol.

  Since the melting point and the thermal decomposition temperature of the 2-pyrrolidone polymer or copolymer treated with the carbodiimide of the present invention are separated, a molded product can be easily produced by melt molding. The melt molding means a method of melting and molding a resin composition, and examples of the molding method include melt spinning, injection molding, extrusion molding, blow molding, and press molding. Examples of the molded product obtained by the melt molding include fibers, films, sheets, tubes, containers, and bars.

  Examples are given below to illustrate the present invention in more detail. However, the present invention is not limited to these examples.

Production Example: Preparation Method of Carbodiimidated Polyamide 4 300 mg of PA4 having a tribranched structure was added to 3 mg of N, N'-dicyclohexylcarbodiimide (DCC (primary), Wako Pure Chemical Industries, Ltd.) 2,2,2- Trifluoroethanol (Tokyo Chemical Industry Co., Ltd.) Add to 30 ml, stir and disperse vigorously, then dissolve and react in an oil bath at 80 ° C. for 1 h, then dry on a flat petri dish. Produced. The cast film shown in the following Table 1 was produced by the same method. Note that all of PA4 used in this example and the comparative example have a three-branch structure.

Test Example 1: Thermal stability of polyamide 4 subjected to carbodiimidization treatment Using the obtained cast film, thermogravimetric / differential thermal analysis (TG-DTA) measurement was performed (device used: differential heat manufactured by SII NanoTechnology Inc.) Thermogravimetric simultaneous measurement device (TG / DTA), EXSTAR TG / DTA6200). FIG. 1 shows a differential thermogravimetric curve (DTG). The peak top of pyrolysis (270 ° C to 350 ° C) from DTG is about 330 ° C for the 5 wt% carbodiimide treated product (Example 3) compared to untreated polyamide 4 (300 ° C) (Comparative Example 1). It can be seen that the temperature is shifted to the high temperature side by 30 ° C., and the entire peak is also shifted to the high temperature side, which is thermally stabilized. In the original polyamide (Comparative Example 1), a small peak due to the melting point is observed at around 265 ° C., but in the 5 wt% carbodiimide treated body (Example 3), the temperature is shifted to 255 ° C. on the low temperature side. It was found to be due to the by-product urea derivative.

Test Example 2: Thermal stability of polyamide 4 when the amount of carbodiimide was changed A cast film was produced in the same manner as in Production Example, except that the amount of DCC shown in Table 2 was used and heat treatment was performed. Thermogravimetric / differential thermal analysis (TG-DTA) measurement was performed using the obtained cast film. FIG. 2 shows a differential thermogravimetric curve (DTG). When the heat stabilization treatment was evaluated, the effect was recognized with the addition amount of 1 to 30 wt% (Examples 4 to 7), but the most remarkable effect was at 5 wt% (Example 5). It was. When the amount of carbodiimide is increased from 5 wt%, a thermal stabilization effect is also exhibited, but the thermal decomposition peak of the DTG curve becomes wider and the thermal decomposition proceeds gradually.

Test Example 3: Thermal stability of polyamide 4 when the treatment temperature was changed Except for the amount of DCC and the amount of HOBt shown in Table 3 (HOBt: 349-03622, Wako Pure Chemical Industries, Ltd.) and heat treatment, A cast film was prepared in the same manner as in the production example, and the obtained cast film was subjected to thermogravimetric / differential thermal analysis (TG-DTA) measurement, and a differential thermogravimetric curve (DTG) is shown in FIG. When the carbodiimide treatment was changed between 80 ° C and 100 ° C, in the DTG analysis, the peak top of thermal decomposition moved to the higher temperature side when treated at 80 ° C, but it stabilized more, but when treated at 100 ° C, the carbodiimide treatment The peak of the urea derivative at around 255 ° C., which is a by-product of NO., Disappeared, and even at the treatment at 80 ° C., the peak at 255 ° C. disappeared when heated after the treatment, for example, once heated to near the melting point and then rapidly cooled.

Test Example 4: Thermal stability of polyamide 4 when the type of carbodiimide is changed
After adding 15 mg of various carbodiimides to 300 mg of PA4 and adding it to 2,2,2-trifluoroethanol: 100 ml and stirring and dispersing it, it was dissolved and reacted in an oil bath at 80 ° C. for 1 h. Then, it was dried on a flat petri dish to produce a cast film. The carbodiimide used was 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC, Tokyo Chemical Industry Co., Ltd.). Thermogravimetric / differential thermal analysis (TG-DTA) measurement was performed using the obtained cast film. FIG. 4 shows a differential thermogravimetric curve (DTG). A thermal stabilization effect was observed in EDAC.

Test Example 5: Thermal stability copolyesteramide of a polyamide 4 copolymer (copoly (2-pyrrolidone / ε-caprolactone), composition ratio 65/35 (molar ratio), linear) 300 mg to DCC 15 mg 2,2,2-trifluoroethanol: Add to 30 ml, stir and disperse vigorously, dissolve in an oil bath at 80 ° C for 1 h, then dry on a flat petri dish. A cast film was produced. The obtained cast film was used for thermogravimetric / differential thermal analysis measurement (devices used: DSC3100S manufactured by MAC Science, TG-DTA2000SA manufactured by Bruker AXS KK). FIG. 5 shows a thermogravimetric curve (TG), a differential thermogravimetric curve (DTG), and a DSC curve. The carbodiimide treatment significantly increased the thermal decomposition temperature compared to untreated, and the thermal resistance was improved by about 50 ° C from the TG curve and about 100 ° C from the thermal decomposition peak position of the DTG curve. DSC results showed that the melting point and pyrolysis temperature were completely separated.

Test Example 6: Thermal stability of polyamide 4 and copolymer when carbodiimide was reacted without solvent Solvent type, amount, carbodiimide type and amount shown in Table 4 were mixed as they were, or a carbodiimide methanol solution (methanol After the resin was impregnated in a quantity of 1.5 ml), it was mixed by a homogenization treatment of drying and reacted at a temperature shown in the table for a certain period of time. The copolyesteramide used was that described in Test Example 5. Thermogravimetric / differential thermal analysis (TG-DTA) measurement was performed using a sample obtained by reacting carbodiimide. FIG. 6 shows a differential thermogravimetric curve (DTG). A certain amount of carbodiimide can be mixed even directly (Fig. 6-1, Examples 12 and 13). However, when it is reacted for a long time at a high temperature in a uniform mixing process, sufficient thermal stabilization is achieved even with mixing of 5 wt% carbodiimide. The effect was obtained (FIGS. 6-2 and 3, Examples 16 and 17).

Test Example 7: Thermal decomposition product of polyamide 4 treated with carbodiimidization
(Analysis method)
Substances generated by pyrolysis were analyzed using pyrolysis-gas chromatograph / mass spectrometer (Py-GC / MS). PY-2020D manufactured by Frontier Lab was used as the thermal decomposition apparatus, and GC / MS QP-5050A manufactured by Shimadzu Corporation was used as the GC / MS apparatus. Pyrolysis was performed by increasing the temperature from 60 ° C. to the injection temperature at 9 K / min. The separation column was DB5-MS (0.25 mm id × 30 m, df = 0.25im), and the injection temperature was 310-320 ° C. He (100 kPa) was used as the carrier gas, the makeup gas flow rate was 100 ml / min, and the split ratio was 100/1. In the MS analysis, the interface temperature was set to 280 ° C., and the ionization method by the EI method was adopted. The scan range was m / z = 29-500, and the scan interval was 0.5 sec.

  (result)

The same PA4_DCC_5 wt% as in Example 3 was used.

(Discussion)
As shown in Table 7, the selectivity of the pyrolysis product 2-pyrrolidone was improved from 78.34% to 89.14% by adding DCC to PA4. If the component derived from DCC is removed, the ratio becomes 92.9%.

Claims (5)

2-pyrrolidone polymer or copolymer treated with carbodiimide ,
The copolymer is a copolymer with lactams,
Polymer or copolymer .   The polymer or copolymer according to claim 1, wherein the carbodiimide is N, N'-dicyclohexylcarbodiimide.   The polymer or copolymer of Claim 1 or 2 which has a linear or branched structure. The molded article containing the polymer or copolymer in any one of Claims 1-3 . A method for increasing the thermal decomposition temperature of a 2-pyrrolidone polymer or copolymer, characterized by treating a 2-pyrrolidone polymer or copolymer with carbodiimide ,
The copolymer is a copolymer with lactams,
Way .

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