HK1257039A1 - Process for producing polyamideimide - Google Patents

Description

Process for preparing polyamideimide

The application is a divisional application of Chinese patent application with application date of 2012, 12 and 17, application number of 201280061393.6, entitled "Low toxicity solvent System for Polyamide imide resin and preparation of solvent System".

Priority

This patent application claims priority from a corresponding provisional patent application No. 61/576,247 entitled "Low sensitivity Solvent System for polymeric reagents and Solvent System Manufacture", filed 12/15/2011 and is incorporated herein by reference.

Technical Field

Embodiments of the invention relate to the field of solvents; more specifically, embodiments of the present invention relate to solvents and their use in the preparation of polyamideimides.

Background

Polyamideimide (PAI) polymers are used in a variety of high performance coating applications due to their excellent heat resistance and high strength. The main routes for the synthesis of polyamideimide polymers in a form convenient for the preparation of coatings are: diisocyanate, typically 4, 4' -methylene diphenyl diisocyanate (MDI), is reacted with trimellitic anhydride (TMA). In this process, the PAI polymer is typically synthesized in a polar aprotic solvent, including, for example, dimethylformamide, dimethylacetamide, N-methylpyrrolidone (NMP), N-methyl amide compounds of N-ethylpyrrolidone. See, for example, U.S. patent nos. 2,421,021, 3,260,691, 3,471,444, 3,518,230, 3,817,926, and 3,847,878. Typical polymer solids levels obtained in this synthetic route are 35% to 45%, which can be further diluted with diluents depending on the end use of the coating application.

Alternative solvents (e.g., tetrahydrofuran, methyl ethyl ketone, gamma-butyrolactone, or dimethyl sulfoxide) have the following disadvantages: for example, too low a boiling point, low polymer solubility, or poor storage stability for use as a reaction solvent can alter the application properties of the polymer resin.

U.S. Pat. No. 4,950,700 and U.S. Pat. No. 5,095,070 exemplify the synthesis of PAI resins from gamma-butyrolactone with N-methyl amide co-solvent and dimethylol ethylene urea as an alternative solvent. However, gamma butyrolactone has neurological attributes that make it subject to regulations and unsuitable for general use in formulations. Dimethylolethylene urea has not been extensively studied for toxicology and contains N-methyl amide functionality suspected of negatively impacting the environment and health. New solvents such as those described in U.S. patent application publication No. 20100076223a1 (e.g., 3-methoxy-N, N-dimethylpropionamide) are too expensive or have not been adequately tested for long-term toxicity.

In addition, protic solvents (e.g., ethyl lactate and propylene glycol) are not suitable for use as the PAI reaction medium.

In practice, although these solvents known in the art are useful for the preparation of PAI or are effective for other organic synthesis reactions, problems with their toxicity are recognized. It would therefore be an advantage to prepare polyamideimide polymers using a synthetic process that has minimal impact on health and safety.

Disclosure of Invention

A process for preparing polyamideimide is disclosed. In one embodiment, the method comprises utilizing at least one aprotic dialkylamide solvent.

In one embodiment of the present invention, a process for preparing a polyamideimide is disclosed, the process comprising: utilizing at least one aprotic dialkylamide solvent, wherein the at least one aprotic dialkylamide solvent is N-formyl morpholine; wherein the molar ratio of the at least one aprotic dialkylamide solvent to the other process co-solvents is from 19:1 to 1: 1; and wherein the other process co-solvent is selected from the group consisting of water, o-xylene, triethylamine, dimethylethanolamine, morpholine, N-methylmorpholine, acetone, trimethylamine, tripropylamine, diethylamine, diisopropylamine, and caprolactam.

In one embodiment of the invention, the method further comprises: diisocyanate was reacted with trimellitic anhydride TMA.

In one embodiment of the invention, the diisocyanate is 4, 4' -methylene diphenyl diisocyanate MDI.

Detailed Description

To achieve a safer alternative, in particular a synthetic route free of the commonly used N-methyl amide solvents, an alternative less toxic solvent is necessary. Acetamide is of concern because: acetamide has lower toxicity and is readily prepared from industrially available dialkylamines, and has long-term low chronic toxicity. In particular, dialkylamides are useful. The low toxicity solvent N-acetylmorpholine (NAM) has been found to be suitable for the preparation of polyamideimide resins. Other useful, low toxicity solvents of the present invention are diethylacetamide (DEAc), di-N-propylacetamide, N-formylmorpholine, diacetylpiperazine, N-diisopropylacetamide (DIPAc), di-N-butylacetamide (DIBAc), di-N-propylacetamide (DIPA), and N-propionylmorpholine (NPM). To achieve a less toxic process, it has now been found that the synthesis of PAI can be accomplished by utilizing the aprotic dialkylamide solvents of the present invention, either alone or in combination with each other, or with the aid of co-solvents which provide a unique solvent system. For example, for various industrial applications of PAI, it may be desirable to use a combination of solvents where a viscosity within a specified range is desired. In addition, these solvents may also act as diluents. To achieve this, a combination of dialkylamide solvents may be used to achieve the desired viscosity. Other preferred co-solvents with low toxicity that can be used in the synthesis of the PAI resin or as diluents to dissolve the PAI resin are: water, o-xylene, triethylamine, dimethylethanolamine, morpholine, N-methylmorpholine, acetone, trimethylamine, tripropylamine, diethylamine, diisopropylamine, and caprolactam.

It has also been found that another advantage of embodiments of the present invention is: by utilizing one or more aprotic dialkylamides in the synthesis process, a one-pot two-step reaction is possible.

Furthermore, the use of these compounds is avoided due to the toxicity of the prior art solvents (such as N-methyl amide) used to synthesize PAI resins.

In particular, the preferred molar ratio of aprotic dialkylamide to other process co-solvents is from about 19:1 to about 1: 1. More preferably in a ratio of about 80:20 to about 70: 30. The most preferred ratio is about 78: 22.

Example (b):

example 1 Process for Synthesis of Co-solvent System: to a 1L four-necked flask equipped with a thermometer, condenser and mechanical stirrer was added 200g of diethylamine. While maintaining a temperature below 55 ℃, 279.1 are added6g of acetic anhydride. 250.15g of morpholine were then added. The reaction was heated to about 130 ℃ until the acetic acid was exhausted (about 8 hours). The conversion was increased by distilled water/excess morpholine.

Example 2(KM-1145): 51g of N-acetylmorpholine (NAM), 0.85g of caprolactam, 19.8g of MDI, 15.65g of TMA were charged and then heated to 100 ℃. The solution was held at 96 ℃ for 1.5 hours. After one night, the temperature was reduced to 70 ℃ and then heated to 130 ℃ for 1.25 hours. The viscosity is too high; 12.2g of NAM co-solvent from example 1 were added.

33.82% solids and 63000cps viscosity (DVII, 23 ℃).

Example 3(JES-3-29): 1.68g of caprolactam, 31.49g of TMA, 39.66g of MDI and 102.12g of NAM co-solvent from example 1 were charged and heated to 110 ℃ over 1.5 hours. Heating to 130 deg.C and monitoring the viscosity until the viscosity is greater than 2000cps/120 deg.C (about 7 hours). Cooled to below 80 ℃ and NAM co-solvent from example 1 was added, maintaining stirring. TEA (triethylamine) was added slowly while maintaining the temperature at 90 ℃. Held at a temperature greater than 60 ℃ for 1 to 2 hours. Water was added to adjust to approximately 28% solids. Heat, maintain at 85 ℃, adjust pH above 8 by TEA and water as needed to achieve homogeneity.

Example 4(KM 277): a 250mL round bottom flask equipped with a mechanical stirrer, condenser and nitrogen bubbler was fitted with: 57.6g of N-acetylmorpholine, 18.9g of o-xylene, 1.3g of caprolactam, 29.7g of methylenediphenyl diisocyanate and 23.5g of trimellitic anhydride. The reaction was heated to 90 ℃ for 2 hours. Then, the reaction temperature was heated to 130 ℃ for 5 hours, and then 14.7g of N-acetylmorpholine and 3.68g of o-xylene were added, and the reactor was cooled to room temperature. Using DVII Bohlenfei(Brookfield) viscometer, at 23 ℃ the final viscosity is 13834 cps.

Example 5(MP-2-11): a 250mL round bottom flask equipped with a mechanical stirrer, condenser and nitrogen bubbler was fitted with: 49g of N-acetylmorpholine, 18.9g of diethylacetamide, 1.3g of o-xylene, 29.7g of methylenediphenyl diisocyanate and 23.6g of trimellitic anhydride. The reaction was heated to 90 ℃ for 2 hours. Then, the reaction temperature was heated to 130 ℃ for 3 hours, and then 3.74g of N-acetylmorpholine was added and the reactor was cooled to 60 ℃. Then, 14.7g of acetone was added dropwise and the reactor was cooled to room temperature. The final viscosity was 3076cps at 23 ℃ using a DVII Bohlenfield viscometer.

Example 6(KM 38): a 500mL round bottom flask equipped with a mechanical stirrer, condenser and nitrogen bubbler was fitted with: 121g of N-acetylmorpholine, 52.9g of methylene diphenyl diisocyanate and 40.92g of trimellitic anhydride. The reaction was heated to 88 ℃ for 3 hours. Then, the reaction temperature was heated to 120 ℃ until the quenching viscosity reached 1680cps (about 2.5 hours), and then 41.81g of N-formylmorpholine and 41.81g of o-xylene were added to quench and cool the reaction. The reactor was cooled to room temperature. The final viscosity was 8573cps at 23 ℃ using a DVII Bohlepflug viscometer.

Example 7(JES-4-21): 50.27g of methylene diphenyl diisocyanate, 38.62g of trimellitic anhydride, and 206.56g of N-formylmorpholine were charged in a 400mL beaker. The reaction mixture was heated to 80 ℃ until approximately 1 equivalent of CO was gradually formed by weight loss₂. Then, the reaction temperature was heated to 130 ℃ until the quench viscosity reached 730cps, and then 41.51g of additional N-formyl morpholine was added to quench the reaction. The reactor was cooled to room temperature. The final solids content was analyzed to be 26.02% and the final viscosity was 10264cps (using a DVII Bohlenfei viscometer).

Whereas many alterations and modifications of the present invention will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description, it is to be understood that any particular embodiment shown and described by way of illustration is in no way intended to be considered limiting. Therefore, references to details of various embodiments are not intended to limit the scope of the claims, which in themselves recite only those features regarded as essential to the invention.

Claims (3)

1. A process for preparing a polyamideimide, said process comprising: utilizing at least one aprotic dialkylamide solvent, wherein the at least one aprotic dialkylamide solvent is N-formyl morpholine;

wherein the molar ratio of the at least one aprotic dialkylamide solvent to the other process co-solvents is from 19:1 to 1: 1; and

wherein the other process co-solvent is selected from the group consisting of water, o-xylene, triethylamine, dimethylethanolamine, morpholine, N-methylmorpholine, acetone, trimethylamine, tripropylamine, diethylamine, diisopropylamine, and caprolactam.

2. The method of claim 1, further comprising: diisocyanate was reacted with trimellitic anhydride TMA.

3. The process of claim 2 wherein the diisocyanate is 4, 4' -methylene diphenyl diisocyanate MDI.