JP4354692B2 - Method for producing polyesteramide copolymer - Google Patents

Description

【００５３】
【発明の効果】
上記表１に示す実施例と比較例との対比で示すように、本発明によれば、脂肪族ポリアミドと、環状エステルの開環重合体である脂肪族ポリエステルと、環状エステルまたは環状アミドとの混合物を、エステル−アミド交換反応および、より低温下での縮重合反応に逐次付すことにより、生分解性に優れ、且つ高強度・高耐熱性で代表される物理特性にも優れ、釣糸、魚網および農業用ネットをはじめとする繊維製品、ならびに食品をはじめとする各種内容物の包装材料として優れた適性を示すポリエステルアミド共重合体が提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to biodegradable and producing how the polyester amide copolymer in harmony and high strength.
[0002]
[Prior art]
In order to reduce the burden on the environment when plastics are disposed of, the development and expansion of use of biodegradable plastics characterized by “non-accumulation” in nature has become a major concern.
[0003]
Representative biodegradable plastics developed to date include aliphatic polyester resins such as polylactic acid oxygen resin, polybutylene succinate, and polycapracton. These biodegradable plastics are , Common disadvantages include (1) low heat resistance, (2) low strength, and (3) difficulty in controlling biodegradability, and sufficient applications and expansion of use have been achieved. Not. Therefore, an attempt to mainly improve the defects of (1) and (2) by imparting biodegradability to the engineering plastics with excellent heat resistance and strength such as polyethylene terephthalate, polybutylene terephthalate, and polyamide by using a copolymer. Has been made. Among these, aliphatic polyamides not only have excellent strength, but also have amide bonds that are present in a large amount in the product, and therefore, aliphatic polyesters that are representative of biodegradable plastics that have been known conventionally and This copolymer is expected to give a polyesteramide copolymer as a biodegradable plastic that has improved the above disadvantages (1) to (3). The polymerization methods for producing polyesteramide copolymers known to date are roughly classified into three types as follows.
[0004]
Monomer (M / M) method (polymerization method 1)
The first is a method of synthesizing a polyesteramide copolymer by a polymerization reaction using all monomers as raw materials (for example, JP-A-7-102061). This method has been known for a long time, but in the case of sufficiently developing biodegradability, the monomer is limited to a specific expensive cyclic compound, and heat resistance and high strength cannot be expressed sufficiently. There is a point.
[0005]
Polymer (P / P) method (polymerization method 2)
The second is a method in which both a high molecular weight polymer and a low molecular weight oligomer are used as raw materials for the amide component and the ester component (for example, JP-A-7-157557). In this method, the polyesteramide copolymer to be produced becomes expensive, the molecular weight of the copolymer to be produced is low, and it is necessary to use a third component in order to increase the molecular weight. Increasing polymer complexity and complexity.
[0006]
Polymer / monomer (P / M) method (polymerization method 3)
The third is a method in which a monomer is used as a raw material of one component of aliphatic polyamide and aliphatic polyester, and a high molecular weight polymer or a low molecular weight oligomer is used as the other raw material. For example, a method using a polyamide and a lactone compound as raw materials (Japanese Patent Laid-Open No. 4-36320) is known, but since the depolymerization of the polymer is promoted after the transesterification by which the monomer acts, the resulting polyesteramide A sufficient increase in the molecular weight of the copolymer could not be obtained, and the strength was still unsatisfactory. For example, 320 to 400 kg / cm ² (about 30 to 40 MPa) is reported as the tensile strength of the molded film using the obtained polyesteramide copolymer. Further, polyester (polylactone), which is considered to be produced together with the copolymer, is separated from the product polyesteramide copolymer as a chloroform-soluble component, and is still unsatisfactory in terms of product yield.
[0007]
[Problems to be solved by the invention]
In view of the above prior art, practically excellent heat resistance, which has physical properties such as mechanical strength, and to provide a method for producing a polyester amide copolymer having biodegradability.
[0008]
[Means for Solving the Problems]
According to the study by the present inventors, in order to obtain a polyesteramide copolymer in which biodegradability, physical strength, and physical properties represented by heat resistance are harmonized, It is desirable to take the form of a block copolymer in which the block average molecular chain length is controlled and to maintain the overall molecular weight (specified by the solution viscosity (inherent viscosity) in the present invention) at a high level. In order to produce a polymer, three types (P) of an aliphatic polyamide (P) as a raw material, an aliphatic polyester (P) that is a ring-opening polymer of a cyclic ester, and a cyclic ester or a cyclic amide (M) are used. / P / M) and subjecting these mixtures to ester-amide exchange and polycondensation reactions under controlled conditions (so-called PPM method) is extremely effective. It has been found.
[0009]
Based on the above knowledge, according to the present invention, it is a copolymer of an aliphatic polyamide and an aliphatic polyester which is a ring-opening polymer of a cyclic ester, and is obtained by dissolving 4.0 g in 1 L of hexafluoroisopropanol. A polyesteramide copolymer having a solution viscosity (inherent viscosity) measured at 25 ° C. using an Ubbelohde viscometer is 0.7 dl / g or more.
[0010]
The method for producing a polyesteramide copolymer of the present invention comprises a mixture of an aliphatic polyamide, an aliphatic polyester that is a ring-opening polymer of a cyclic ester, and a cyclic ester or a cyclic amide, and a melting point of the polyamide of about 300 ° C. This is characterized in that the ester-amide exchange reaction is carried out by maintaining the mixture in a heated and melted state at a temperature between 1 and 2 until it becomes transparent, and then polycondensation is carried out at a lower temperature.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method for producing a polyester amide copolymer of the present invention, according to the process are sequentially described.
[0012]
1. Raw material (aliphatic polyamide)
The first raw material used in the method for producing a polyesteramide copolymer of the present invention is an aliphatic polyamide. This aliphatic polyamide is composed of substantially the same monomer as the aliphatic polyamide constituting the product polyesteramide copolymer. In the polymerization process of the present invention, the aliphatic polyester described later or an ester-amide based on the monomer is used. Because it undergoes an exchange reaction, it has a molecular weight significantly greater than the block units of the aliphatic polyamide in the product polyesteramide copolymer.
[0013]
Specifically, as the aliphatic polyamide, a condensation polymer of an aliphatic dicarboxylic acid and an aliphatic diamine and a ring-opening polymer of a cyclic amide (lactam) are used. More specifically, a polyamide (nylon 6) is used. ), Polyamide 6,6 (nylon 6,6), polyamide 12 (nylon 12), polyamide 6,10 (nylon 6,10) or a copolymer thereof. Among them, cyclic amides such as polyamide 6 and polyamide 12 are preferable, and polyamide 6 (nylon 6) is particularly preferable in order to obtain a balance between strength characteristics and biodegradability of the product polyesteramide copolymer. The aliphatic polyamide as a raw material preferably has a number average molecular weight in the range of 600 to 100,000, particularly 10,000 to 25,000. When the number average molecular weight is less than 600, it is difficult to increase the degree of polymerization during the condensation reaction, and when it exceeds 100,000, stirring tends to be difficult.
[0014]
(Aliphatic polyester (ring-opening polymer of cyclic ester))
The second raw material used in the method for producing a polyesteramide copolymer of the present invention is an aliphatic polyester that is a ring-opening polymer of a cyclic ester. Specific examples of the cyclic ester include β-lactone, γ-lactone, Examples include lactones such as δ-lactone and ε-lactone, glycolide (cyclic dimer of glycolic acid) and lactide (cyclic dimer of lactic acid). -Ε-lactone is preferably used. The aliphatic polyester as a raw material preferably has a number average molecular weight in the range of 500 to 500,000, particularly 4,000 to 100,000. When the number average molecular weight is less than 500, it is difficult to increase the degree of polymerization during the condensation reaction. Moreover, when 500,000 is exceeded, stirring will become difficult easily.
[0015]
(Cyclic ester or cyclic amide)
The third raw material used in the method for producing a polyesteramide copolymer of the present invention is a cyclic ester or a cyclic amide.
[0016]
Specific examples of the cyclic ester include lactones and glycolides corresponding to the aliphatic polyester, and specific examples of the cyclic amide include lactams, which are also preferable examples of the corresponding monomer of the aliphatic polyamide.
[0017]
These cyclic esters or cyclic amides significantly promote ester-amide exchange under heating between aliphatic polyamides and aliphatic polyesters, enabling ester-amide exchange at lower temperatures and resulting polyester amide copolymers It has the effect | action which prevents low molecular weight reduction. The action of the cyclic ester or cyclic amide is thought to be due to the structural approximation with the monomer of the aliphatic polyester or aliphatic polyamide. In this sense, the most preferred cyclic ester is ε-caprolactone, and the most preferred cyclic amide is ε-caprolactam.
[0018]
More specifically, polycaprolactone and polyamide 6 are ester-amides at a high temperature (Japanese Patent Publication No. 57-26688) or in the presence of water (Japanese Patent Laid-Open No. 7-157557). A method for producing a polyesteramide copolymer by an exchange reaction is known. However, in the system in which these polymers are reacted with each other, the copolymer reaction does not proceed completely, and the DSC measurement in the amorphous state does not show a single elevated temperature crystallization temperature. Furthermore, since the reaction is carried out at a temperature considerably higher than the melting points of the polyamide and polyester components, there is a problem that thermal decomposition occurs in the ester and amide components until the reaction is completed, and sufficient mechanical strength cannot be obtained. .
[0019]
On the other hand, according to the present invention, in addition to the aliphatic polyamide and the aliphatic polyester, in the presence of a cyclic ester or a cyclic amide, a transparent homogeneous liquid state showing a temporary completion state of the ester-amide exchange (according to this) The crystallization temperature in the temperature rising process from the amorphous state in the resulting polyester amide copolymer is obtained in a relatively short time, and then the condensation polymerization is proceeded at a lower temperature as a whole. Polyesteramide copolymers have been found that have undergone ester-amide exchange sufficient to provide biodegradability while maintaining a sufficiently high molecular weight (solution viscosity) to provide mechanical strength.
[0020]
According to the knowledge of the present invention and the like, in the produced polyesteramide copolymer, the average molecular chain length in the polyamide block is 3 or more, and the solution viscosity (inherent viscosity) of the polyesteramide copolymer is 0.7 dl / g or more. More preferably, it is 0.8 dl / g or more, and more preferably 0.9 dl / g or more, in order to increase physical properties such as heat resistance and mechanical strength of the produced polyesteramide copolymer. Remarkably preferred. On the other hand, the average molecular chain length of the polyester block in the polyesteramide copolymer is preferably smaller than that in the polyamide block, and more specifically within the range of 1-2.
[0021]
The use of the raw material components is determined so that the above-described preferred molecular weight and average molecular chain length in the produced polyesteramide copolymer can be realized.
[0022]
More specifically, the proportion in which the polyamide content in the resulting polyesteramide copolymer is 50 to 95 mol%, particularly 60 to 90 mol%, and the polyester content is 5 to 50 mol%, particularly 10 to 40 mol% is preferable. Used. In the above three raw materials (aliphatic polyamide, aliphatic polyester and cyclic ester or cyclic amide), the aliphatic polyamide is 25 to 85 mol%, particularly 30 to 81 mol%, and the aliphatic polyester is 4.5 to 25 mol. %, In particular 9 to 20 mol%, cyclic esters in the range 0.5 to 25 mol%, in particular 1 to 20 mol%, or cyclic amides in the range 9 to 30 mol%, in particular 9.5 to 25 mol%, It is determined so as to satisfy the range of the polyamide content and the polyester content in the resulting polyesteramide copolymer.
[0023]
According to the method for producing a polyesteramide copolymer of the present invention, the above-mentioned aliphatic polyamide, aliphatic polyester, and cyclic ester or cyclic amide are heated at a temperature between about 190 ° C. and about 300 ° C., which is the melting point of the polyamide. The ester-amide exchange is preferably carried out at a temperature in the range 210-280 ° C. In this case, generally, a conventional transesterification catalyst such as (anhydrous) zinc acetate, zinc stearate, tetra-n-butyl titanate is used in an amount of 0.1 to 10 parts by weight, particularly 0 Coexist in the range of 2-1.0 parts by weight. By holding the raw material mixture at the above temperature for 1 to 15 hours, particularly 2 to 10 hours, a transparent homogeneous liquid state indicating the end of the ester-amide exchange is reached (accordingly, in the produced polyesteramide copolymer) The crystallization temperature in the temperature rising process from the amorphous state is unified).
[0024]
When the system reaches a transparent homogeneous liquid state, the temperature of the system is changed as soon as possible, specifically 150 to 260 ° C., particularly 170 to 230 ° C., and in the temperature range (preferably less than the ester-amide exchange reaction temperature. The polycondensation is carried out by lowering the temperature to a temperature lower by at least 0 ° C., particularly 20 to 100 ° C. Even after reaching the transparent homogeneous liquid state, if the system is stopped at the ester-amide exchange temperature, the depolymerization of the polyamide block proceeds, and the average molecular chain length required for the physical properties of the produced polyesteramide copolymer is 3 or more. Will not be satisfied.
[0025]
This condensation polymerization is continued until the stirring torque increases and becomes almost constant.
[0026]
Manufacturing method through obtained Lupo Li ester amide copolymer of the present invention described above, the form of a block copolymer of aliphatic polyamide and an aliphatic polyester as described above, the inherent viscosity corresponding to the number-average molecular weight 0.7 dl / g or more, preferably 0.8 dl / g or more, more preferably 0.9 dl / g or more, the average molecular chain length of the polyamide block is 3 to 10, more preferably 4 to 8, and the average molecule of the polyester block The chain length is in the range of 1 to 2, more preferably in the range of 1.2 to 1.7. Further, at the time of temperature rise, a single crystallization temperature is shown in a temperature range of 10 to 150 ° C., and a melting point is shown in a range of 150 to 210 ° C.
[0027]
The polyesteramide copolymer according to the present invention is a biodegradable plastic having improved physical properties, fiber products such as fishing lines, fish nets and agricultural nets, and various film products useful as food packaging materials through extrusion and stretching. Can be used for molding.
[0028]
[Example]
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The polyesteramide copolymer obtained in each example was measured for the following physical properties.
[0029]
1. Thermal properties Measurement was performed using DSC7 manufactured by Perkin Elmer. The measurement temperature range is 10 ° C to 250 ° C. The heating / cooling rate is 10 ° C / min.
[0030]
2. Primary structure (Structural analysis method by ¹³ C-NMR)
Ester / amide ratio The ratio is determined by the size of each carbonyl carbon peak of polyester / polyamide.
[0031]
-Bond ratio Focus on the ester bond and the methylene carbon peak adjacent to the carbonyl carbon involved in the bond. When an amide-ester or ester-amide peak is generated by the ester-amide exchange reaction, the peak of the methylene carbon bonded to the carbonyl carbon involved in the bond is shifted. It is possible to determine each bond ratio of amide-amide, amide-ester, ester-ester, ester-amide from the ratio of the original peak to the shifted peak and the ester / amide ratio.
[0032]
-Average block length Assuming that the produced polylactone amide is polymerized as a single molecular chain, it can be obtained from the result of arrangement so as to match the bond ratio obtained earlier.
[0033]
3. Biodegradability (under compost conditions)
Measurement was performed using a microorganism oxidative decomposition apparatus (product name “MODA”) manufactured by Ryosan Products. That is, 10 g of the pulverized sample was mixed with a microbial source and sea sand, filled into a reaction tube, and carbon dioxide was removed from the reaction tube maintained at 58 ° C. at a rate of 20 ml / min for 45 days. Supply. From the reaction cylinder, carbon dioxide ammonia and water from microbial decomposition react. Of these, only carbon dioxide is selectively recovered, its amount is measured, and carbon dioxide to be generated from the total amount of carbon in the sample. The ratio with the amount was calculated, and the ratio of 3% or more was regarded as biodegradable, and the ratio of less than 3% was regarded as no biodivision.
[0034]
4). Solution viscosity A sample solution was prepared so that the sample amount was 4.0 g per 1 L of hexafluoroisopropanol. The viscosity of the test solution was measured using a Ubbelohde viscometer in a 25 ° C. water bath.
[0035]
5. Linear strength ◎ Sample preparation A monofilament having a diameter of about 0.2 mm was molded using a φ35 m extruder under the following conditions.
[0036]
[Outside 1]
Extrusion temperature: 195 ° C
・ Cooling tank temperature: 5 ℃
・ One-stage stretching: 4.30 times @ 23 ° C
-Two-stage stretching: 1.57 times @ 140 ° C
-Total draw ratio: 6.75 times-Heat treatment and relaxation: None [0037]
◎ Strength Measurement The tensile strength of the obtained monofilament was measured using Tensilon (RTM-100 type) manufactured by Orientec.
[0038]
[Outside 2]
Test temperature: 23 ° C
・ Sample length: 300mm
・ Tensile speed: 300mm / min
[0039]
(Example 1)
In a reaction vessel, 6 nylon, polycaprolactone and ε-caprolactone were charged in a 70: 21: 9 molar ratio, maintained at 220 ° C. in a nitrogen atmosphere, and then the set temperature was increased to 260 ° C. 6 After the nylon is melted, gradually increase the stirring speed, and further raise the temperature of the system to 270 ° C., then add 0.5 parts by weight of zinc acetate (catalyst) to 100 parts by weight of the total charge, An ester-amide exchange reaction was initiated.
[0040]
The reaction was continued at 270 ° C., and after about 6 hours, the system changed from a cloudy state to a transparent homogenized state. Therefore, it was determined that the ester-amide exchange was completed, and the temperature was lowered to 220 ° C. while stirring was continued. . Condensation polymerization was continued at this temperature for about 10 hours, and then cooled to obtain a polyesteramide copolymer according to the present invention.
[0041]
The obtained polyesteramide copolymer has a melting point = 180 ° C., a temperature-rising crystallization temperature = 27 ° C. (single), an average molecular chain length in the polyamide block = 5.7, an average molecular chain length in the polyester block = 1. 4. Inherent viscosity (η _inh ) = 1.0 dl / g. The composting treatment under microbial oxidation conditions at 58 ° C. for 45 days showed a carbon dioxide gas generation rate of about 15%, and was judged to be biodegradable. Further, when a monofilament having a diameter of about 0.2 mm was formed and the linear tensile strength was measured, a value of 670 MPa was shown.
[0042]
The summary of the production of the polyesteramide copolymer and the result of the characteristic measurement are shown in Table 1 below together with the results of the following examples and comparative examples.
[0043]
(Example 2)
A polyesteramide copolymer was produced in the same manner as in Example 1 except that the ester-amide exchange reaction at 270 ° C. was continued for 4 hours after reaching the transparent liquid state in about 6 hours, and the physical properties were measured. went.
[0044]
As a result, a decrease in the inherent viscosity and average molecular chain length of the polyamide was observed, and the linear tensile strength of the monofilament was also reduced to 320 MPa, but still at the level obtained by the conventional method (55 MPa according to Comparative Example 3 described later). In comparison, a considerably high strength was obtained.
[0045]
(Example 3)
As in Example 1, except that 6 nylon, polycaprolactone and ε-caprolactam were used as raw materials in a molar ratio of 49:30:21 and the ester-amide exchange reaction was carried out at a temperature of 300 ° C. for 1.3 hours. A polyesteramide copolymer was produced and measured for physical properties.
[0046]
(Comparative Example 1)
Polyesteramide copolymer was used in the same manner as in Example 1 except that 6 nylon, polycaprolactone and ε-caprolactone were used as raw materials in a molar ratio of 50:35:15 and the polycondensation reaction at 220 ° C. was not performed. A coalescence was produced and the physical properties were measured.
[0047]
(Comparative Example 2)
Physical properties for comparison were measured using commercially available 6 nylon (“A1020BRL” manufactured by Unitika). Melting point, inherent viscosity, linear strength, etc. showed a slightly higher temperature than the polyesteramide copolymer of the example, but the amount of carbon dioxide generated in the compost treatment was 0%, and no biodegradability was observed. .
[0048]
(Comparative Example 3)
As raw materials, except that 6 nylon, polycaprolactone and ε-caprolactone were used in a molar ratio of 70:30, the ester-amide exchange reaction was performed at a temperature of 280 ° C. for 2 hours, and the polycondensation reaction at 220 ° C. was not performed. In the same manner as in Example 1, a polyesteramide copolymer was produced and measured for physical properties.
[0049]
The obtained polyesteramide copolymer showed peaks of crystallization temperature at 13 ° C. and 21 ° C. when the DSC was heated, indicating that the ester-amide exchange reaction was insufficient, and the linear tensile strength was 55 MPa. It showed a fairly low value.
[0050]
(Comparative Example 4)
According to the description in JP-A-7-157557, a polyesteramide was produced by the P / P method. That is, as a raw material, 6 nylon and polycaprolactone were charged at a molar ratio of 70:30, and 4 parts by weight of water and 0.5 parts by weight of catalyst were added thereto. The mixture was heated to 270 ° C. under a nitrogen atmosphere and reacted for 4 hours with stirring. Thereafter, the atmosphere in the apparatus was reduced, water was distilled off, and when the torque was sufficiently increased, the pressure was returned to normal pressure. After discharging, the molten reaction product was allowed to cool to obtain a copolymer.
[0051]
The results of the above examples and comparative examples are collectively shown in the following Table 1.
[0052]
[Table 1]

[0053]
【The invention's effect】
According to the present invention, as shown in comparison with the examples and comparative examples shown in Table 1 above, the aliphatic polyamide, the aliphatic polyester which is a ring-opening polymer of a cyclic ester, and the cyclic ester or cyclic amide. By subjecting the mixture to an ester-amide exchange reaction and a condensation polymerization reaction at a lower temperature in succession, it is excellent in biodegradability and excellent in physical properties represented by high strength and high heat resistance. In addition, a polyesteramide copolymer is provided that exhibits excellent suitability as a packaging material for various products including textile products such as agricultural nets and foods.

Claims (2)

A mixture of an aliphatic polyamide, an aliphatic polyester that is a ring-opening polymer of a cyclic ester, and a cyclic ester or a cyclic amide is heated and melted at a temperature between the melting point of the polyamide and 300 ° C. to be in a transparent state. A process for producing a polyesteramide copolymer, characterized in that the ester-amide exchange reaction is continued until it is maintained, and then condensation polymerization is advanced at a lower temperature. The method for producing a polyesteramide copolymer according to claim 1 , wherein the aliphatic polyamide is polyamide 6, the cyclic ester is ε-caprolactone, and the cyclic amide is ε-caprolactam .