TWI729601B - Method for manufacturing polyamide foam molded body - Google Patents

Abstract

Provided is a method for manufacturing a polyamide foam molded body, including: performing a polymerization reaction of a monomer composition for forming a polyamide copolymer; mixing a supercritical fluid of carbon dioxide foaming agent with the polyamide copolymer under pressure for forming a mixture; and releasing the pressure of the mixture for foaming the polyamide copolymer. The monomer composition comprises 15 to 20 wt.% of aminocaproic acid, 15 to 20 wt.% of adipic acid and 60 to 70 wt.% of a dimeric diamine. The dimeric diamine is a C30-40 aliphatic branched diamine having a molecular weight between 450 and 650 g/mole, a melting point of less than -30℃ and a boiling point of larger than 350℃. The method provided by the present invention can be performed under realtively low temperature, has a high foaming yield and the foam molded body therefrom is not likely to collapse.

Description

Method for manufacturing polyamide foamed molded body

The present invention relates to a method for manufacturing a foamed molded body, and particularly relates to a method for manufacturing a polyamide foamed molded body.

In the prior art, materials used to manufacture foams include polystyrene, polyurethane, polyolefin, aliphatic polyester, and the like. Among them, for the technology of foaming under pressure with supercritical carbon dioxide foaming agent, there are very few studies on using polyamide as a raw material for foaming.

Specifically, for nylon foam, it has the problems of insufficient melt strength, difficulty in foaming, and easy collapse of the foamed molded body after foaming. In addition, with regard to the technology of foaming with the existing nylon elastomer, although the nylon elastomer is modified to make it easy to foam, its foamed molded body is still prone to collapse.

In detail, in the prior art, the representative technology of using polyamide-co-polyether type materials as the raw material of polyamide foamed molded products is the United States Patent Application No. US 2019/0203009A1 (BASF ), US Patent Application No. US 2019/0071570 A1 (Arkema), Wang et al. published in European Polymer Journal 103 (2018) 68-79, etc. The aforementioned polyamides in the prior art include polyamide 6 (polyamide 6), polyamide 66 (polyamide 66), polyamide 11 (polyamide 11), polyamide 10 (polyamide 10) and other oligomers. However, the aforementioned prior art polyamides still have the following shortcomings: (1) The polymer contains polyether as a component, resulting in poor oxidation resistance and thermal cracking resistance of the polymer; (2) due to polyether Most of the glass transition temperature (T _g ) is lower than room temperature or even lower than zero degrees Celsius. When the foamed molded body foamed by it is cooled back to normal temperature, the foamed molded body is prone to collapse.

In addition, in the prior art, there have been some studies using biomass long-carbon number compounds, such as biomass dimer dicarboxylic acid, which is an aliphatic branched dicarboxylic acid with 30-40 carbons. Aliphatic branched C30-40 dimeric dicarboxylic acid (Aliphatic branched C30-40 dimeric dicarboxylic acid) replaces the aforementioned polyether to form a polyamide used to produce a polyamide foam molded body. For example, Canadian Patent Application No. CA 3035447 A1 (Construction Research & Technology GMBH, DE) discloses the use of polyamide-co-dimeric acid-co-isocyanate type composition To form a polyamide foam molded body. However, the disadvantage of this composition is that isocyanate-type compounds must be used to solve the disadvantages of weak copolymerization reactivity of dimer dicarboxylic acid, less controllable copolymer product structure, and large physical property variability.

Accordingly, in the prior art, there is still a need to provide a manufacturing method for forming a polyamide foam molded body to solve the above technical problems, that is, there is a need to provide a structure that can achieve both high foaming rate and foaming The manufacturing method that is not easy to collapse has two main demands.

In order to solve the above-mentioned technical problems, the present invention provides a method for producing polyamide foamed molded products, which uses bio-compound dimer diamine (dimeric diamine) as the main monomer compound to synthesize polyamide copolymer. And through supercritical carbon dioxide blowing agent to produce polyamide foam.

An embodiment of the present invention provides a method for manufacturing a polyamide foam molded body The method includes: performing a polymerization reaction with a monomer composition to form a polyamide copolymer; mixing a supercritical carbon dioxide blowing agent with the polyamide copolymer under pressure to form a mixture; and The pressure of the mixture is released so that the polyamide copolymer is foamed to form the polyamide foam molded body. The monomer composition includes 15 to 20% by weight of aminocaproic acid, 15 to 20% by weight of adipic acid and 60 to 70% by weight of dimer diamine, and the dimer diamine is C30- The aliphatic branched diamine of 40 has a molecular weight of 450 to 650 g/mol, a melting point of less than -30°C, and a boiling point of greater than 350°C.

In a preferred embodiment, the polyamide copolymer has a relative viscosity of 1.5 to 1.8, a melting point of 85 to 120°C, a glass transition temperature of 10 to 20°C, and a crystallization temperature of 48 to 52°C.

In a preferred embodiment, the expansion ratio of the polyamide copolymer is 7 to 12 times.

In a preferred embodiment, the supercritical carbon dioxide blowing agent is mixed with the polyamide at a pressure of 100 to 150 bar and a temperature of 80 to 120°C.

In a preferred embodiment, in the monomer composition, the molar ratio of aminocaproic acid to the dimer diamine is between 0.97 and 1.03.

In a preferred embodiment, the step of performing the polymerization reaction with the monomer composition to form the polyamide copolymer includes: combining the aminocaproic acid, adipic acid and dimer diamine Mixing in a polymerization tank in a nitrogen environment; raising the temperature of the polymerization tank to above 190°C and stirring for at least 20 minutes; raising the temperature of the polymerization tank to above 220°C and stirring for at least 3 hours; and putting the polymerization tank Increase the temperature to above 240°C again for at least 2 hours.

In a preferred embodiment, the polymerization tank is heated to above 190°C and In the step of stirring for at least 20 minutes, the stirring speed is 10 to 30 rpm.

In a preferred embodiment, in the step of heating the polymerization tank to above 220° C. and stirring for at least 3 hours, the stirring speed is increased from about 40 rpm to about 105 rpm as the temperature increases.

In a preferred embodiment, raising the temperature of the polymerization tank to above 240° C. for at least 2 hours before, further comprising shutting off the nitrogen supply of the polymerization tank.

In a preferred embodiment, it further includes: after the polymerization tank is heated to a temperature above 240° C. for at least 2 hours, the reaction is terminated and the blanking and pelletizing procedures are performed in a normal pressure and nitrogen environment.

The main technical means of the present invention is that the manufacturing method of the polyamide foam molded body provided by the embodiment of the present invention is to synthesize a polyamide copolymer for foaming by using a specific monomer composition, and With the use of a supercritical carbon dioxide foaming agent, the obtained polyamide foamed body has the advantages of low-temperature foaming, high foaming rate and no collapse after foaming.

The following is a specific embodiment to illustrate the implementation of the "method for manufacturing polyamide foam molded body" disclosed in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be based on different viewpoints and applications, and various modifications and changes can be made without departing from the spirit of the present invention. The following embodiments will further describe the related technical content of the present invention in detail, but the disclosed content is not intended to limit the present invention. Technical category.

First, the embodiment of the present invention provides a method for manufacturing a polyamide foam molded body. In the manufacturing method of the present invention, the monomer composition is first polymerized to form a polyamide copolymer. The monomer composition includes a monomer compound for polymerization reaction, which includes 15 to 20% by weight of aminocaproic acid (ACA), 15 to 20% by weight of adipic acid (AA), and 60% by weight. To 70% by weight of dimeric diamine (dimeric diamine).

Specifically, the present invention uses the above-mentioned biomass compound dimer diamine to replace the dimeric dicarboxylic acid (dimeric dicarboxylic acid) used in the prior art as one of the monomer compounds to be manufactured for foam molding The polyamide copolymer. The resulting polyamide copolymer is Polyamide 6-co-dimeric diamine-co-adipic acid.

In fact, the dimer diamine used in the examples of the present invention is C30-40 (having 30-40 carbons) aliphatic branched diamine, and has a molecular weight between 450 to 650 g/mol, Melting point less than -30°C and boiling point greater than 350°C. In a preferred embodiment, the dimer diamine has a molecular weight between 500 and 600 g/mol. In a most preferred embodiment, the dimer diamine has a molecular weight of 540 g/mol.

In summary, since the dimer diamine used in the embodiment of the present invention has better copolymerization reactivity than the dimer dicarboxylic acid used in the prior art, and the structure of the product of the copolymerization reaction is easier to control, In the embodiment of the present invention, it is not necessary to use an isocyanate-based compound in the monomer composition. In detail, the monomer composition of the present invention may not include a polyether compound. Dimer diamine has a higher bulk density (bulk density) than polyether compounds, excellent oxidation resistance, heat resistance and hydrophobicity, high modulus, and compared to polyamide-copolyether type polymerization The material has high resistance to hydrolysis. As a result, the polyamide foam molded body formed from the dimer diamine of the embodiment of the present invention as one of the monomer compounds is also less prone to collapse.

In an embodiment of the present invention, in the monomer composition, the molar ratio of aminocaproic acid to dimer diamine is between 0.97 and 1.03. Controlling the components in the monomer composition within the above range can ensure that the prepared polyamide copolymer has excellent characteristics, such as elongation greater than 670%, and makes it easier to foam.

In addition, in the polyamide copolymer made from the monomer composition of the embodiment of the present invention, the hard segment is a polyamide 6 structure, and the monomer composition Does not contain hexamethylenediamine (HMDA) as one of the monomer compounds, so HMDA will not easily slip out during the polymerization reaction, resulting in a large variation in the ratio of amines and acids, and a limited increase in the molecular weight of polyamide copolymers The problem.

Next, the steps of producing a polyamide copolymer by using the monomer composition of the embodiment of the present invention will be explained in detail. The polyamide copolymer of the present invention can be synthesized from a monomer composition through a single-step polymerization reaction. For example, in the embodiment of the present invention, the step of synthesizing the polyamide copolymer includes: mixing aminocaproic acid, adipic acid, and dimer diamine in a polymerization tank in a nitrogen environment; heating the polymerization tank The temperature of the polymerization tank is raised to above 190°C and stirring for at least 20 minutes; the temperature of the polymerization tank is raised to above 220°C and the stirring is carried out for at least 3 hours;

It can be seen from the above content that in the embodiment of the present invention, all the monomer compounds in the monomer composition are mixed in a polymerization tank in a single step, and the polymerization reaction is completed by means of stirring, heating, and pressure control. A specific example will be provided later to illustrate one aspect of the synthesis process of the present invention.

In a preferred embodiment of the present invention, in the step of raising the temperature of the polymerization tank to above 190°C and stirring for at least 20 minutes, the stirring speed is 10 to 30 rpm; the temperature of the polymerization tank is again raised to above 220°C and stirring at least In the 3-hour step, the stirring speed increased from about 40 rpm to about 105 rpm as the temperature increased. In addition, before raising the temperature of the polymerization tank to 240° C. or more for at least 2 hours, it further includes shutting off the nitrogen supply of the polymerization tank.

After the polyamide copolymer is obtained through the polymerization reaction, the product can be subjected to feeding and pelletizing procedures in a normal pressure and nitrogen environment for subsequent foaming procedures. The polyamide copolymer formed by the polymerization reaction may have a relative viscosity of 1.5 to 1.8, a melting point of 85 to 120°C, a glass transition temperature of 10 to 20°C, and a crystallization temperature of 48 to 52°C.

Next, the manufacturing method of the polyamide foam molded body provided by the embodiment of the present invention further includes mixing the supercritical carbon dioxide blowing agent and the polyamide copolymer under pressure to form a mixture. In a preferred embodiment, the supercritical carbon dioxide blowing agent is mixed with polyamide at a pressure of 100 to 150 bar and a temperature of 80 to 120°C. Then, the pressure of the mixture is released to foam the polyamide copolymer to form a polyamide foam molded body. In the embodiment of the present invention, the foam expansion ratio of the polyamide copolymer is 7 to 12 times.

Hereinafter, the present invention will be exemplified by specific examples.

Synthesis Example: Synthesis of Polyamide Copolymer

Add 73 grams (0.5565 mol, 17.5% by weight) of aminocaproic acid (CAS No. 60-32-2, purchased from Alfa Aesar), 73 grams (0.4995 mol, 17.5% by weight) of adipic acid (CAS No. 124-04-9, available from Acros Organics) and 270 grams (0.5 mol, 65% by weight) of dimer diamine (Priamine ^™ , available from Croda International). The temperature of the polymerization tank was raised to 190°C while gradually increasing the rotation speed of stirring (the rotation speed was 20 rpm). After stirring for 20 minutes, the temperature was increased to 220°C and the rotation speed was increased to 40 rpm. After the temperature at the top of the tower rises, the rotation speed is increased to 105 rpm for 3 hours. After 3 hours, the nitrogen supply was turned off, and the temperature was increased to 240°C under low pressure (about 1 to 5 Torr) for 2 hours. The reaction can be terminated after reaching the torque value (torque) that can be generally blanked, and the blanking and pelletizing procedures can be carried out under normal pressure and nitrogen environment.

The NMR spectrum data of the polyamide copolymer are shown below. _{^{1 H-NMR (CF 3 COOD}} , ppm) = 3.9 (amide, -CONHC H 2); 3.1 (-C H 2 CONH -); 2.0-2.4 ( aliphatic H); 1.2-2.0 (aliphatic H). As shown in Table 1. IR (cm ^-1 ) = main absorption peak 1634 (amide); 1545 (amide); 1459 (amide)

Specific examples and comparative examples

Please refer to Tables 1 and 2 below. Examples 1 to 4 are polyamide copolymers prepared by synthesizing the examples using the monomer composition provided by the present invention, and Comparative Example 1 is a polyamide copolymer prepared by the control group. Comparative Examples 2 to 4 are existing polyamide copolymer products (commercially available nylon 6 and Pebax series products). The detailed composition ratios of the monomer compositions of Examples 1 to 4 and Comparative Example 1 are listed in Table 1 below, and the measurement results of various physical properties of Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 2 below. Show.

In Table 2 below, the relative viscosity (RV) is measured using an Ostwald viscometer with a capillary inner diameter of 0.5 cm (mm) and in accordance with ASTM D789. The glass transition temperature (Tg) is the data from the analysis of the Dynamic Mechanical Analyzer (Dynamic Mechanical Analyzer, DMA) instrument.

Table 1

的結晶溫度。

The crystallization temperature.

It can be seen from Table 2 above that the polyamide copolymers of Examples 1 to 4 have the characteristics of low melting point and glass transition temperature close to room temperature.

Next, the above-mentioned polyamide copolymer is foamed. In Table 3 below, the formula of the above example 1 is used to make the polyamide copolymer, and the foaming process includes soaking the polyamide copolymer in liquid nitrogen for 2 minutes, then cutting into rectangles of appropriate size and placing them in hot air. 1 day after oven. Next, the sample is placed in a syringe-type high-pressure syringe pump, and contained in a container coexisting _{with supercritical carbon dioxide (CO 2) fluid.} Under the pressure and temperature listed in Table 3, the supercritical blowing agent carbon dioxide was incorporated into the polyamide copolymer, and the sample was impregnated in the supercritical carbon dioxide for 4 hours. Then the sample is cooled and cured, and the pressure is released to form a polyamide foam molded body. The foam expansion ratios of the samples of Example 1 and Comparative Example 3 at different temperatures and pressures are shown in Table 3 below. For the calculation of the expansion ratio of foaming, this experiment uses an electronic balance to measure and calculate the specific gravity of the sample before and after foaming, and then calculate the expansion ratio of the sample by formula 1:

Among them, Wa is the weight of the material measured in air, Wl is the weight of the material measured in water, and ρl is the specific gravity of water.

It can be seen from Table 3 that the polyamide copolymer of Example 1 of the present invention has excellent foaming effects under the conditions of 88°C/100bar, 85°C/150bar and 88°C/150bar. In contrast, although the material of Comparative Example 3 can be foamed under the condition of 120°C/100bar to form a foamed molded body, its foaming expansion ratio is only 3.19.

Subsequently, the polyamide copolymers manufactured by the formulations of Examples 2 to 4 and Comparative Example 1 were also foamed. The foaming process is as described above for Example 1 and Comparative Example 3. The foaming conditions and the foaming expansion ratio of the polyamide foam are shown in Table 4 below.

In summary, from the experimental results of the examples and comparative examples, it can be seen that the polyamide foam molded body produced by the method of manufacturing the polyamide foam molded body according to the embodiment of the present invention, under various temperatures and pressures It has excellent foaming effect (that is, excellent foaming ratio), and due to the selection and control of the formula used to form the polyamide copolymer, the polyamide copolymer as the foaming raw material has It has good physical properties and is advantageous for the manufacture of foamed molded products.

[Feasible effects of the embodiment]

In summary, the beneficial effect of the present invention is that the manufacturing method of the polyamide foam molded body provided by the embodiment of the present invention is to synthesize the polyamide for foaming by using a specific monomer composition. The copolymer and the use of supercritical carbon dioxide foaming agent make the obtained polyamide foam molded body have the advantages of low-temperature foaming, high foaming rate and no collapse after foaming.

In detail, the manufacturing method of the polyamide foam molded product provided by the embodiment of the present invention uses a specific ratio of aminocaproic acid, adipic acid and dimer diamine as monomer compounds for copolymerization to form The polyamide copolymer, especially the dimer diamine, which is the raw material for foaming, is an aliphatic branched diamine with a specific carbon number and a specific molecular weight, melting point and boiling point. By using the above-mentioned dimer diamine, the monomer composition in the embodiment of the present invention does not need to use an isocyanate compound to enhance the reactivity of the copolymerization reaction and control the structure of the product of the copolymerization reaction.

In addition, the manufacturing method of the polyamide foam molded body provided by the embodiment of the present invention uses the supercritical fluid carbon dioxide as a foaming agent, which is a popular development in the industry, to foam the polyamide copolymer. Since the critical temperature of the carbon dioxide fluid is close to room temperature, non-toxic, widely sourced, and low cost, this manufacturing method belongs to the green process technology and is environmentally friendly and has high industrial value.

Although the embodiments of the present invention are disclosed in the above-mentioned more detailed manner, those with ordinary knowledge in the art can understand that various modifications of the present invention can be made without departing from the definitions defined in the present invention. It is carried out under the scope of the present invention in the scope of the attached patent application. Therefore, further modifications of the examples of the present invention will not deviate from the technology of the present invention.

Claims (10)

A manufacturing method of a polyamide foamed molded body, which comprises: Perform a polymerization reaction with a monomer composition to form a polyamide copolymer; Mixing a supercritical carbon dioxide blowing agent with the polyamide copolymer under pressure to form a mixture; and Releasing the pressure of the mixture so that the polyamide copolymer is foamed to form the polyamide foamed molded body; Wherein, the monomer composition comprises 15 to 20% by weight of aminocaproic acid, 15 to 20% by weight of adipic acid and 60 to 70% by weight of dimer diamine, and the dimer diamine is C30-40 aliphatic branched diamine and has a molecular weight of 450 to 650 g/mol, a melting point of less than -30°C, and a boiling point of greater than 350°C. The method for producing a polyamide foam molded article according to claim 1, wherein the polyamide copolymer has a relative viscosity of 1.5 to 1.8, a melting point of 85 to 120°C, and a glass transition temperature of 10 to 20°C And the crystallization temperature of 48 to 52 ℃. The method for producing a polyamide foam molded article according to claim 1, wherein the expansion ratio of the polyamide copolymer is 7 to 12 times. The method for producing a polyamide foam molded article according to claim 1, wherein the supercritical carbon dioxide blowing agent is mixed with the polyamide at a pressure of 100 to 150 bar and a temperature of 80 to 120°C . The method for producing a polyamide foam molded article according to claim 1, wherein, in the monomer composition, the molar ratio of glycine to the dimer diamine is 0.97 to 1.03. The method for producing a polyamide foam molded article according to claim 1, wherein the monomer The step of performing the polymerization reaction of the composition to form the polyamide copolymer includes: Mixing the aminocaproic acid, adipic acid and dimer diamine in a polymerization tank in a nitrogen environment; Raising the temperature of the polymerization tank to above 190°C and stirring for at least 20 minutes; Raise the temperature of the polymerization tank to above 220°C again and stir for at least 3 hours; and The temperature of the polymerization tank was raised to 240°C or higher again for at least 2 hours. The method for producing a polyamide foam molded article according to claim 6, wherein in the step of raising the temperature of the polymerization tank to 190°C or higher and stirring for at least 20 minutes, the stirring speed is 10 to 30 rpm. The method for producing a polyamide foam molded article according to claim 6, wherein in the step of heating the polymerization tank to 220° C. or more and stirring for at least 3 hours, the stirring speed is increased as the temperature rises. Increased from about 40 rpm to about 105 rpm. The method for producing a polyamide foam molded article according to claim 6, wherein the temperature of the polymerization tank is raised to 240° C. or more for at least 2 hours before, and the method further includes shutting off the nitrogen supply of the polymerization tank. The method for producing a polyamide foam molded article according to claim 6, further comprising, after the polymerization tank is heated again to 240°C or higher for at least 2 hours, terminating the reaction and placing it in a normal pressure and nitrogen environment Carry out cutting and pelletizing procedures.