JP5283058B2 - Polyamide 4 copolymer having a branched structure and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamide 4 copolymer modified in material properties (mechanical property and thermal property) by controlling a polymeric chain structure and a polymeric chain composition, and to provide its producing method. <P>SOLUTION: The method is provided for obtaining the polyamide 4 copolymer including a structure derived from an initiator by carrying out copolymerization with &epsi;-caprolactam using a basic polymerization catalyst and the initiator with a branch structure of two or more branches in polymerizing 2-pyrrolidone and the polyamide 4 copolymer having a special structure including a structure derived from the initiator, obtained by polymerization with &epsi;-caprolactam using the basic polymerization catalyst and the initiator having the branch structure of two or more branches in polymerizing 2-pyrrolidone. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a polyamide 4 copolymer whose physical properties (mechanical properties, thermal properties, etc.) can be modified by controlling the polymer chain structure and the polymer chain composition. Since the polyamide 4 copolymer obtained by the present invention has excellent physical properties such as high strength and high melting point, it can be used as an engineering plastic. Furthermore, 2-pyrrolidone, a raw material monomer that is biodegraded by microorganisms in soil and activated sludge, has high environmental compatibility and can be used in a wide range of applications.

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 due to difficulties in processing and problems in cost, practical application has been abandoned. Polyamide 4 has excellent thermal properties such as a high melting point, but has a drawback that melt molding is difficult because the melting point and the thermal decomposition temperature are close to each other.

Patent Document 2 discloses that a special structure or a functional group is formed in a polymer chain or at a polymer chain end by polymerizing 2-pyrrolidone using a basic polymerization catalyst and a carboxylic acid compound having a special structure or a special functional group. It is described that a 2-pyrrolidone polymer having a group can be produced, and that various physical properties such as thermal stability and moldability of the 2-pyrrolidone polymer can be controlled and improved. Patent Document 2 discloses only a homopolymer of 2-pyrrolidone.
US Pat. No. 2,739,959 Japanese Patent No. 3453600 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) Bar-Zakay, 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)

The present invention utilizes the fact that the structure of the initiator can be introduced into the polyamide 4 polymer chain by the ring-opening polymerization of 2-pyrrolidone proceeding by an activated monomer mechanism. In other words, the special structure (branched structure) derived from the initiator and the structural unit (ε-caprolactam) derived from other monomers coexist in the polyamide 4 polymer chain, thereby controlling the polymer chain structure and the polymer chain composition. Thus, the main object is to provide a polyamide 4 copolymer having improved physical properties (mechanical properties and thermal properties) and a method for producing the same.

In the polymerization of 2-pyrrolidone (PRN), the present inventors used a basic polymerization catalyst and an initiator having a branched structure (two or more branches) to copolymerize with ε-caprolactam (CLM). The knowledge that the said objective can be achieved by doing was acquired. Based on these findings, the present invention has been completed through further studies, and provides the following polyamide 4 copolymer and a method for producing the same.
Item 1. A copolymer of 2-pyrrolidone and ε-caprolactam having a branched structure of two or more branches derived from an initiator.
Item 2. Item 2. The copolymer according to Item 1, wherein the branched structure derived from the initiator is bi- or tri-branched.
Item 3. Item 3. The copolymer according to Item 2, wherein the initiator is terephthaloyl chloride or 1,3,5-benzenetricarbonyl trichloride.
Item 4.2 Derived from an initiator obtained by copolymerization with ε-caprolactam using a basic polymerization catalyst and an initiator having a branched structure of two or more branches during polymerization of 2-pyrrolidone A polyamide 4 copolymer having a special structure characterized by comprising a structure.
Item 5. Item 5. The polyamide 4 copolymer according to item 4, wherein the initiator having a branched structure of two or more branches is an initiator having a branched structure of two or three branches.
Item 6. Item 6. The polyamide 4 copolymer according to item 5, wherein the initiator having a branched structure of two or three branches is terephthaloyl chloride or 1,3,5-benzenetricarbonyltrichloride.
Item 7. In polymerization of 2-pyrrolidone, a copolymer derived from an initiator is obtained by copolymerizing with ε-caprolactam using a basic polymerization catalyst and an initiator having a branched structure of two or more branches. A process for producing a polyamide 4 copolymer having a special structure, characterized in that a polyamide 4 copolymer is obtained.
Item 8. Item 8. The method for producing a polyamide 4 copolymer having a special structure according to Item 7, wherein an initiator having a branched structure of two or three branches is used as the initiator having a branched structure of two or more branches.
Item 9. Item 9. A method for producing a polyamide 4 copolymer having a special structure according to Item 8, wherein terephthaloyl chloride or 1,3,5-benzenetricarbonyltrichloride is used as the initiator having a branched structure of two or three branches.

According to the present invention, a special structure (branched structure) derived from an initiator and a structural unit (ε-caprolactam) derived from another monomer coexist in a polyamide 4 polymer chain, By controlling, physical properties (mechanical properties, thermal properties) can be modified. Furthermore, the polyamide 4 copolymer of the present invention is biodegraded by microorganisms in soil or activated sludge.

  Hereinafter, the present invention will be described in detail.

The polyamide 4 copolymer having a special structure of the present invention is copolymerized with ε-caprolactam using a basic polymerization catalyst and an initiator having a branched structure of two or more branches in the polymerization of 2-pyrrolidone. It includes a structure derived from an initiator, obtained by performing.

In addition, the method for producing a polyamide 4 copolymer having a special structure according to the present invention uses ε-caprolactam by using a basic polymerization catalyst and an initiator having a branched structure of two or more branches in the polymerization of 2-pyrrolidone. Is a method of obtaining a polyamide 4 copolymer containing a structure derived from an initiator.

  The mixing ratio of the 2-pyrrolidone and ε-caprolactam can be any ratio from (2-pyrrolidone / ε-caprolactam) = (99/1) to (2-pyrrolidone / ε-caprolactam) = (1/99). Yes, the properties of the polyamide 4 copolymer obtained can be controlled by the ratio.

  Examples of the basic polymerization catalyst include alkali metal (lithium, sodium, potassium, etc.), alkali metal or alkaline earth metal hydrides (lithium hydride, sodium hydride, Calcium hydride, etc.), basic organometallic compounds (n-butyllithium, etc.) can be used. Among these, sodium is preferable in terms of ease of handling and yield.

The amount of the basic catalyst used is 1.0 to 18 mol%, preferably 1.5 to 9 mol%, more preferably 3 to 4.5 mol%, based on 1 mol of the total amount of 2-pyrrolidone and ε-caprolactam. Polymerization is possible even when the amount used exceeds the above lower limit and upper limit. However, ingenuity is considered necessary to increase the yield.

  As the initiator to be used, carboxylic acid derivatives such as carboxylic acid halides and carboxylic acid esters and broadly activated carboxylic acid derivatives can be used. Some specific examples include benzoyl chloride (BzC), terephthaloyl chloride (Bz14DCC), 1,3,5-benzenetricarbonyl trichloride (Bz135TCC), acetyl chloride, stearoyl chloride, N-acetyl-ε-caprolactam ( aCLM). An initiator including a structure to be introduced into the polyamide 4 copolymer may be used.

In particular, an initiator having a branched structure having two or more branches is preferred. Examples of the initiator having two branches include terephthaloyl chloride, and examples of the initiator having three branches include 1,3,5-benzenetricarbonyl trichloride.

  The initiator is used in an amount of 0.5 to 16.5 mol%, preferably 0.5 to 7.5 mol%, more preferably 0.5 to 3 mol%, based on 1 mol of the total amount of 2-pyrrolidone and ε-caprolactam.

In the reaction, a hydrocarbon solvent such as hexane can also be used. In this case, by selecting an initiator (e.g. stearoyl chloride), dispersion polymerization becomes possible,
A powdery or flaky polyamide 4 copolymer is obtained. On the other hand, when bulk polymerization is performed without a solvent, there is an advantage that the removal of the solvent is unnecessary, but a pulverizing operation is required because a bulky polyamide 4 copolymer is obtained. It is necessary to use both methods properly according to the purpose.

In the method of the present invention, the polymerization can be carried out under conditions of about 20 to 180 ° C. The temperature is more preferably about 50 to 150 ° C, and still more preferably about 75 to 125 ° C. However, when the ratio of ε-caprolactam as a charged monomer is high, it is necessary to set the melting point or higher.

  In order to remove generated hydrogen, the reaction is preferably performed under reduced pressure.

Under such conditions, a basic polymerization catalyst was added to 2-pyrrolidone, and after this basic polymerization catalyst was reacted and disappeared, that is, after reacting for about 2 to 4 hours, ε-caprolactam was added to obtain a uniform mixture. The reaction mixture is taken. In order to obtain a uniform reaction mixture, 2-pyrrolidone, ε-caprolactam, and sodium may be mixed simultaneously. Further, a carboxylic acid compound may be added and reacted for about 12 to 168 hours.

  Then, what is necessary is just to collect | recover the produced | generated polymers according to a conventional method.

To control the mechanical and thermal properties of polyamide 4 copolymer, change the blending ratio of 2-pyrrolidone and ε-caprolactam, the type of basic catalyst or initiator, reaction temperature or reaction time, etc. Is mentioned.

Examples of the polyamide 4 copolymer having a special structure in the polymer chain include the following. The ring-opening polymerization of 2-pyrrolidone proceeds by an activated monomer mechanism, and the polymerization product reflects the structure of the initiator, so it is terminally linear for monofunctional initiators and bilaterally linear for bifunctional initiators. A trifunctional initiator can synthesize a three-way branched polyamide 4 copolymer. These two-way or three-way branched polyamide 4 copolymer can be used as it is as a polymer material excellent in molding processability and mechanical strength, and further used as an additive to other plastics. It can be used as an improver for workability and mechanical strength.

  The polyamide 4 copolymer of the present invention may be either a random copolymer or a block copolymer. The polyamide 4 copolymer of the present invention is biodegradable.

  Examples are given below to illustrate the present invention in more detail.

In each of the following Examples, the number average molecular weight and the weight average molecular weight were calculated from the results of measurement using polymethyl methacrylate as a standard substance with a high-speed GPC system (manufactured by Tosoh Corporation, (HLC-8220GPC system)). The polymer composition ratio PRN / CLM was calculated by measuring ¹ HNM and estimating the ratio of methylene protons derived from CLM units to methylene protons derived from PRN units.

Example 1
The three-way branched polyamide 4 copolymer was synthesized as follows. 2-Pyrrolidone 3.40 g (40 mmol) and sodium 0.034 g (1.5 mmol), which had been purified to remove water by purification in a flask equipped with a vacuum apparatus, were added and heated at 50 ° C. under reduced pressure to react with sodium. After sodium was completely reacted, 1.13 g (10 mmol) of ε-caprolactam was added to obtain a homogeneous reaction mixture (in addition, 2-pyrrolidone, ε-caprolactam and sodium were mixed at the same time to obtain a homogeneous reaction mixture). You may do it.) Next, 0.066 g (0.25 mmol, 0.75 mmol as an acyl group) of 1,3,5-benzenetricarbonyltrichloride was added, and the pressure was reduced at 75 ° C. for several hours, followed by argon substitution, and the polymerization reaction was performed for a total of about 24 hours. went. The polymerization product was dissolved in trifluoroethanol, and the basicity with sodium was neutralized using formic acid, followed by filtration with a glass filter to remove insoluble matters. The obtained polymerization product filtrate was concentrated, precipitated with acetone, and purified by washing with distilled water and methanol. As a result, 2.37 g (yield 52%) of a pale red solid was obtained. Polymer composition ratio PRN / CLM = 90/10. Weight average molecular weight 272 × 10 ³ . Melting point 266 ° C.

Example 2
The three-way branched polyamide 4 copolymer was synthesized as follows. 0.034 g (1.5 mmol) of sodium was added to 2.98 g (35 mmol) of 2-pyrrolidone and 1.70 g (15 mmol) of ε-caprolactam, and sodium was reacted by heating at 50 ° C. under reduced pressure. After the sodium has completely reacted, add 0.03 g (0.25 mmol) of 1,3,5-benzenetricarbonyltrichloride, depressurize at 75 ° C for several hours, and perform argon substitution for a total of 24 hours for the polymerization reaction. It was. Purification was carried out in the same manner as in Example 1. As a result, 2.16 g (yield 46%) of a pale red solid was obtained. Polymer composition ratio PRN / CLM = 78/22. Weight average molecular weight 263 × 10 ³ . Melting point 265 ° C.

Example 3
The three-way branched polyamide 4 copolymer was synthesized as follows. Conducted using 2.55 g (30 mmol) of 2-pyrrolidone, 2.26 g (20 mmol) of ε-caprolactam, 0.034 g (1.5 mmol) of sodium, 0.066 g (0.25 mmol) of 1,3,5-benzenetricarbonyl trichloride The same operation as in Example 2 was performed. As a result, 0.61 g (yield 13%) of an ivory solid was obtained. Polymer composition ratio PRN / CLM = 70/30. Weight average molecular weight 83 × 10 ³ . Melting point 155, 246 ° C. (2 peaks).

Example 4
The three-way branched polyamide 4 copolymer was synthesized as follows. Conducted using 2.55 g (30 mmol) of 2-pyrrolidone, 2.26 g (20 mmol) of ε-caprolactam, 0.034 g (1.5 mmol) of sodium, 0.066 g (0.25 mmol) of 1,3,5-benzenetricarbonyl trichloride The same operation as in Example 1 was performed. As a result, 1.01 g (yield 21%) of a pale orange solid was obtained. Polymer composition ratio PRN / CLM = 59/41. Weight average molecular weight 196 × 10 ³ . Melting point 154 ° C.

Example 5
The three-way branched polyamide 4 copolymer was synthesized as follows. Conducted with 2.13 g (25 mmol) of 2-pyrrolidone, 2.83 g (25 mmol) of ε-caprolactam, 0.034 g (1.5 mmol) of sodium and 0.066 g (0.25 mmol) of 1,3,5-benzenetricarbonyl trichloride The same operation as in Example 2 was performed. As a result, 1.06 g (yield 21%) of an ivory solid was obtained. Polymer composition ratio PRN / CLM = 51/49. Weight average molecular weight 240 × 10 ³ . Melting point 158 ° C.

Example 6
The three-way branched polyamide 4 copolymer was synthesized as follows. Conducted with 2-pyrrolidone 1.70 g (20 mmol), ε-caprolactam 3.39 g (30 mmol), sodium 0.034 g (1.5 mmol), 1,3,5-benzenetricarbonyltrichloride 0.066 g (0.25 mmol) The same operation as in Example 1 was performed. As a result, 1.00 g (yield 19%) of a white solid was obtained. Polymer composition ratio PRN / CLM = 40/60. Weight average molecular weight 258 × 10 ³ . Melting point 148, 156 ° C. (2 peaks).

Example 7
The three-way branched polyamide 4 copolymer was synthesized as follows. 2-pyrrolidone 3.83 g (45 mmol), ε-caprolactam 0.57 g (5 mmol), sodium 0.034 g (1.5 mmol), 1,3,5-benzenetricarbonyltrichloride 0.066 g (0.25 mmol) The same operation as in Example 1 was performed. As a result, 2.46 g (yield 56%) of a pale red solid was obtained. Polymer composition ratio PRN / CLM = 96/4. Weight average molecular weight 157 × 10 ³ . Melting point 266 ° C.

Example 8
The bilinear polyamide 4 copolymer was synthesized as follows. The same procedure as in Example 1 was performed using 3.83 g (45 mmol) of 2-pyrrolidone, 0.57 g (5 mmol) of ε-caprolactam, 0.034 g (1.5 mmol) of sodium, and 0.076 g (0.375 mmol) of terephthaloyl chloride. went. As a result, 0.86 g (yield 20%) of a white solid (powder) was obtained. Polymer composition ratio PRN / CLM = 87/13. Weight average molecular weight 47 × 10 ³ . Melting point 253 ° C.

Example 9
The bilinear polyamide 4 copolymer was synthesized as follows. The same procedure as in Example 1 was performed using 2.40 g (40 mmol) of 2-pyrrolidone, 1.13 g (10 mmol) of ε-caprolactam, 0.034 g (1.5 mmol) of sodium, and 0.076 g (0.375 mmol) of terephthaloyl chloride. went. As a result, 0.90 g (yield 20%) of a pale red solid was obtained. Polymer composition ratio PRN / CLM = 72/28. Weight average molecular weight 43 × 10 ³ . Melting point 161, 256 ° C. (2 peaks).

Example 10
The bilinear polyamide 4 copolymer was synthesized as follows. The same procedure as in Example 1 was performed using 2.55 g (30 mmol) of 2-pyrrolidone, 2.26 g (20 mmol) of ε-caprolactam, 0.034 g (1.5 mmol) of sodium, and 0.076 g (0.375 mmol) of terephthaloyl chloride. went. As a result, 1.76 g (yield 37%) of a white solid (powder) was obtained. Polymer composition ratio PRN / CLM = 66/34. Weight average molecular weight 55 × 10 ³ . Melting points 156 ° C., 262 ° C. (2 peaks).

Example 11
As a control, a terminal linear polyamide 4 copolymer was synthesized as follows. The same operation as in Example 1 was performed using 3.40 g (40 mmol) of 2-pyrrolidone, 0.57 g (5 mmol) of ε-caprolactam, 0.034 g (1.5 mmol) of sodium, and 0.105 g (0.75 mmol) of benzoyl chloride. . As a result, 1.58 g (yield 35%) of a white solid (powder) was obtained. Polymer composition ratio PRN / CLM = 91/9. Weight average molecular weight 28 × 10 ³ . Melting point 265 ° C.

Example 12
As a control, a terminal linear polyamide 4 copolymer was synthesized as follows. 2-pyrrolidone 3.83 g (45 mmol), ε-caprolactam 1.13 g (10 mmol), sodium 0.034 g (1.5 mmol), N-
The same operation as in Example 1 was performed using 0.116 g (0.75 mmol) of acetyl-ε-caprolactam. As a result, 1.28 g (yield 29%) of a pale red solid was obtained. Polymer composition ratio PRN / CLM = 90/10
. Weight average molecular weight 29 × 10 ³ . Melting point 264 ° C.

The following can be seen from the above Examples 1 to 12 and the experimental results in the table. (1) The weight average molecular weight of the polyamide 4 copolymer is higher than that of a terminal linear polyamide 4 copolymer synthesized using a monofunctional initiator, using a bifunctional or trifunctional initiator. The synthesized two-way linear polyamide 4 copolymer and three-way branched polyamide 4 copolymer are higher. In particular, when a trifunctional initiator is used, a high molecular weight that is considered to be caused by the formation of a soluble microgel occurs. (2) The melting point of the polyamide 4 copolymer can be controlled by its composition. In particular,
When the CLM content exceeds 40% in the polymer composition ratio, the melting point is significantly lowered.

Example 13
Using the polyamide 4 copolymer synthesized based on the above-mentioned examples, a film was prepared by a solvent casting method using trifluoroethanol as a solvent, and tensile strength and elongation at break were measured. No measurable film was formed with the terminal linear polyamide 4 copolymer as a control sample. However, a good film was formed with the two-way linear polyamide 4 copolymer and the three-way branched polyamide 4 copolymer.

Example 14
A film prepared by the solvent casting method was processed into a rectangular test piece having a thickness of 53 μm (average), a length of 15 mm, and a width of 5 mm. Tensile strength and elongation at break were measured using a universal testing machine (Auto com / AC-50, TS Engineering), and 15 measurements were averaged for each specimen (see table).

  Compared to terminal linear polyamide 4 copolymers synthesized using monofunctional initiators, bilinear polyamide 4 copolymers synthesized using bifunctional or trifunctional initiators, three-way branched It was confirmed that the type polyamide 4 copolymer can be modified in mechanical properties (tensile strength, elongation at break). In particular, when a trifunctional initiator is used, in addition to the effect of entanglement due to branching, it is considered that the mechanical properties have been improved by increasing the molecular weight considered to be due to the formation of a soluble microgel.

For tensile strength and elongation at break, polyamide 6 consisting of CLM units is 70 to 83 MPa, 300% (MARUZEN Polymer Dictionary, Maruzen 1994, p980), and polyamide 4 consisting of PRN units is 72 MPa, 51% (Kawasaki) , N. et al: Polymer: 46, 9987-9993 (2005)), but the polyamide 4 copolymer with a branched structure containing a CLM unit and a PRN unit has a slightly lower tensile strength from the same level. However, the elongation at break increased significantly. From this, it was found that copolymerization with a branched structure is effective as a method for modifying the tensile properties and elongation at break, which are mechanical properties of polyamide 4.

Example 15
The biodegradability in activated sludge, which is a characteristic of the polyamide 4 copolymer, was examined as follows. Disperse 200 mg of polymer sample in 500 ml of inorganic culture solution, add 30 ml of standard activated sludge provided by the Chemical Substance Evaluation Research Organization, aerate with carbon dioxide with stirring, and culture tank Was passed through an alkali trap (0.025 N sodium hydroxide aqueous solution) to capture carbon dioxide generated by the metabolism of microorganisms. The generated carbon dioxide was measured every week for 4 weeks using a total organic carbon meter (TOC-V _CSH , Shimadzu Corporation) as the amount of inorganic carbon. The biodegradability of the polymer sample was evaluated by the following formula using the amount of carbon dioxide generated when 100% decomposed as a theoretical value (see table).
Biodegradation (%) = carbon dioxide (measured value) / carbon dioxide (theoretical value) x 100

From the table, to clarify the tendency of polyamide 4 copolymer for biodegradability (degradation experimental conditions are affected by the microbial flora that changes from time to time in activated sludge, it is difficult to maintain constant conditions Although it is necessary to increase the number of measurement examples, biodegradability can be imparted by adding PRN units to polyamide 6 (CLM content 100%) which is difficult to decompose at least under normal conditions. It turns out that it is possible.

Claims (6)

Have a 2 or more branches of the branched structure derived from the initiator, .epsilon.-caprolactam content of a polymer composition ratio is not less than 28 mol%, a copolymer of 2-pyrrolidone and .epsilon.-caprolactam. The copolymer according to claim 1, wherein the initiator-derived branched structure is bi-branched or tri-branched. In the polymerization of 2-pyrrolidone, it contains a structure derived from an initiator obtained by copolymerizing with ε-caprolactam using a basic polymerization catalyst and an initiator having a branched structure of two or more branches. Thus, a polyamide 4 copolymer having a special structure characterized in that the content of ε-caprolactam is 28 mol% or more in terms of polymer composition ratio . The polyamide 4 copolymer according to claim 3, wherein the initiator having a branched structure of two or more branches is an initiator having a branched structure of two or three branches. Polyamide 4 containing a structure derived from an initiator by copolymerizing with ε-caprolactam using a basic polymerization catalyst and an initiator having a branched structure of two or more branches in the polymerization of 2-pyrrolidone. A method for producing a polyamide 4 copolymer having a special structure, characterized by obtaining a copolymer , wherein the polyamide 4 copolymer has a polymer composition ratio of ε-caprolactam content of 28 mol% or more . 6. The method for producing a polyamide 4 copolymer having a special structure according to claim 5 , wherein an initiator having a branched structure of two or three branches is used as the initiator having a branched structure of two or more branches.