JPH031332B2 - - Google Patents

Description

[Detailed description of the invention]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyamide compositions, and more particularly to polyamides that can be formed into transparent articles. In the past, several methods have been proposed for producing transparent polyamides for use in articles such as films, pulp, rods, and containers. One such method proposes using bis(p-aminocyclohexyl)methane as the diamine component and polycondensing it with isophthalic acid (US Pat. No. 2,696,482). Although the polyamides obtained in this way have excellent transparency, they have a high melt viscosity, which makes it difficult to form molded articles. Other proposed methods use terephthalic acid and isophthalic acid as dicarboxylic acid components and polycondensate them with alkyl group-containing hexamethylene diamine. However, the polyamides obtained by this method have poor resistance to organic solvents such as methanol. Yet another proposed method uses selected amounts of bis(p-aminocyclohexyl)methane, hexamethylene diamine, terephthalic acid, and isophthalic acid to make a copolymer (U.S. Pat.
3597400). However, the melt viscosity of this copolymer remains high, and the copolymer provides articles with undesirable dimensional changes and undesirable water absorption levels in certain solvents. It is an object of the present invention to provide polyamide resins of low melt viscosity that yield transparent articles with low dimensional change in solvents and low levels of water absorption. The polyamide resin of the present invention contains a) 60-90 mol% isophthalic acid based on the total amount of acids present, b) 10-40 mol% terephthalic acid based on the total amount of acids present, c) 98 based on the total amount of amines present. ~92 mol % of hexamethylene diamine, and d the lower limit of the mol % present is 2 mol % of the total amount of amine present and the upper limit is 1/11 of the mol % of a) present, and bis(p- At least 59% by weight of aminocyclohexyl)methane consists essentially of polycondensates formed from units of bis(p-aminocyclohexyl)methane, which are either trans-trans or cis-trans isomers. a polyamide, provided that the amounts of acids a) and b) together are about 100 mol % and the amounts of amines c) and d) are about 100 mol % together, and the polyamide has a temperature of 30,000 poise at 280°C. It is a polyamide resin for molding, which has a melt viscosity lower than that of polyamide resin. The polyamide resin for molding of the present invention has shear stress
The melt viscosity at 280° C. measured at 10 ⁵ dynes/cm ² is lower than 30,000 poise, preferably lower than 20,000 poise. This polyamide can be manufactured by a known polymer condensation method at the above composition ratio. To form a high molecular weight polymer, the total moles of acid used should be the same as the total moles of diamine used. Bis(p-aminochlorohexyl)methane (hereinafter referred to as
PACM) is usually a mixture of stereoisomers. The ratio of these isomers is important in the present invention. At least 59% by weight of the PACM should be either trans-trans or cis-trans isomers. In this case, the heat distortion temperature is surprisingly high when more than 59% of either isomer is present. Polymers can be made using isophthalic acid and terephthalic acid as well as their derivatives such as chloride. Although the polymerization can be carried out by known polymerization techniques such as melt polymerization, solution polymerization and interfacial polymerization techniques, it is preferred to carry out the polymerization by melt polymerization techniques. This method produces high molecular weight polyamides. PACM, hexamethylene diamine, terephthalic acid and isophthalic acid in melt polymerization,
The diamine component and dicarboxylic acid component are mixed in such an amount that the ratio is substantially equimolar and the composition of these four monomers satisfies the above-mentioned mol%. These components are heated to a temperature above the melting point of the resulting polyamide, but below its degradation temperature.
Due to the volatility of hexamethylene diamine, a slight excess thereof is used in the mixture. The heating temperature is
Within the range of 170-300℃. Pressure is from atmospheric pressure to
Can be within the range of 300psig. The method of addition of the starting monomers is not critical. For example, a binding salt of a diamine and an acid can be created and mixed. It is also possible to disperse the diamine mixture in water, add to this dispersion at elevated temperature the amount of the acid mixture described above to form a solution of the nylon salt mixture, and subject this solution to polymerization. If desired, monovalent amines or preferably organic acids may be added as viscosity modifiers to the starting salt mixture or its aqueous solution. In addition, various additives commonly used in the polyamide of the present invention,
It is also possible, for example, to add heat stabilizers, UV stabilizers, glass or mineral reinforcing agents, toughening agents, anti-flame agents, plasticizers, antioxidants and pigments before or after the polymerization. The polyamides of the present invention have excellent transparency, chemical resistance, thermal stability and melt formability and are therefore suitable for the production of various moldings and molded articles, such as various types of films, plates, pipes, rods and containers. Useful. The present invention will be explained in more detail below with reference to Examples. Copolymer resins were prepared by reacting aqueous solutions of the respective resin salts in an autoclave at temperatures typically below 300° C. and pressures typically 300 psig for a suitable period of time, about 2 hours. When most of the water has evaporated, the pressure is gradually reduced to atmospheric pressure and the reaction is continued under reduced pressure until the desired molecular weight is reached.
If low molecular weights are desired, the final stage of the reaction can be carried out at atmospheric conditions rather than under reduced pressure. Example 1...Salt ratio 6I/6T/PACM I/
Production of copolymer of PACM T (66.8/28.6/3.2/1.4) 6I is a unit of hexamethylene diamine (HMD) and isophthalic acid (I), 6T is a unit of HMD and terephthalic acid (T), PACM I is PACM and I, and PACM T represents the unit of PACM and T. Hexamethylene diamine (HMD) in 140lb of water
(82.03% HMD) and 2.6 lb of bis(p-aminecyclohexyl)methane containing 62% cis-trans isomer, 20% trans-trans isomer and 18% cis-cis isomer. Added. Heat the mixture and add 41.2 lb of isophthalic acid
and 17.7 lbs of terephthalic acid were added. The pH of the solution was adjusted to 8.62 using a small amount of HMD. To this salt solution is emulsified 49 g of sodium phenylphosphinate as a heat stabilizer, 97 g of 4,4'-butylidenebis(6-t-butyl-m-cresol) as a resistive oxidizing agent, and 10% emulsion of dimethylpolysiloxane as an antifoaming agent. liquid 20
ml and 14 ml of glacial acetic acid for molecular weight adjustment were added.
The temperature of the solution was maintained at 70-80°C. This salt mixture was then charged to an autoclave. The mixture was heated to 175°C and subjected to a pressure of 180 psig. Water is gradually released while maintaining the pressure at 180 psig until the solution is sufficiently concentrated and the temperature of the batch is lowered.
The temperature reached 226℃. The pressure was then gradually reduced to atmospheric pressure and vacuum applied. The batch temperature was then increased to approximately 270°C. When the desired molecular weight was reached, the autoclave was pressurized with nitrogen gas and the polymer was extruded into cylindrical strands, quenched in water and cut into pellets. For each acid and diamine used, the tetrapolymer contained 70% isophthalic acid and 30% terephthalic acid based on 100% total amount of acids, 96.5% HMD and 3.5% HMD based on 100% total amount of diamine.
It contained PACM. Control Example A - Preparation of 6I/6T/PACM I/PACM T (63.5/27.2/6.5/2.8) This polymer was prepared as in the above example. To 140 lbs of water was added 46.5 lbs of HMD (82.03% concentration) and 5.25 lbs of the same bis(p-aminocyclohexyl)methane used in Example 1. Heat the mixture and add 41.2lb of isophthalic acid and terephthalic acid.
Added 17.7lb. Then, use a small amount of HMD to adjust the PH.
Adjusted to 8.60. To this salt solution were added 49 g of sodium phenylphosphinate, 97 g of 4,4'-butylidenebis(6-t-butyl-m-cresol), 20 ml of a 10% emulsion of polydimethylsiloxane, and 14 ml of glacial acetic acid. Control example B...6I/6T/PACM I/PACM
Preparation of T (57.6/24.7/12.4/5.3) As above, 140 lb of water, 44.2 lb of hexamethylene diamine (concentration 81.45%), and 10.5 lb of bis(p-aminocyclohexyl)methane as used in Example 1. I used it to make salt preparation. Diamine to isophthalic acid 41.2lb and terephthalic acid 17.7lb
and the pH was adjusted to 8.50. 49 g of sodium phenylphosphinate in this salt solution,
4,4'-Butylidene bis(6-t-butyl-m-
cresol) 97g, polydimethylsiloxane 10
% emulsion and 14 ml of glacial acetic acid were added. Control example C...6I/6T/PACM I/PACM
Preparation of T (63.5/27.2/6.5/2.8) This polymer is the polymer of Example 1 except that the PACM used contains approximately 48% trans-trans isomer and 40% cis-trans isomer. is the same as Control Examples A and B above are representative of US Pat. No. 3,597,400. Effect of solvent Copolymer molded bar (5 x 1/2 x 1/4)
The changes in weight and dimensions in various solvents were examined by immersing them in various solvents for the indicated times and measuring the weight and dimensions each time. The results are shown in Tables 1-5.

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Table: Hygroscopicity Hygroscopicity data were obtained by measuring the weight gain after immersing the samples in boiling water or boiling water containing potassium acetate (1.25 lb KAC/1 lb H ₂ O) for 24 hours. The results are shown in Table 6. Table 6 50%RH 100%RH Number (Boiling KAC) (Boiling Water) Example 1 1.86% 5.29% Control A 2.14% 6.32% Control B 2.04% 8.13% Melt Viscosity Dry sample was heated at 280°C in a constant speed rheometer. Tested. Reduce the force required to extrude resin from 10 inches/minute to
Measurements are taken at a series of predetermined piston speeds and shear stresses varying from 0.02 inches/min, and the shear rate and apparent melt viscosity are calculated. A constant speed rheometer consists of a heated extrusion device with a piston that can be driven at a predetermined speed by an Instron tester. The force required to force the resin through the orifice is measured and recorded by a compression load cell. 0.0468 with L/D=16
An inch orifice was used for all samples. Pour the required amount of resin from the test tube into the heated drum and compact with hand pressure. The piston is then installed and lowered (by the Instron crosshead) into just contact with the polymer, and the timer is started. Compress the polymer (at a speed of 1 inch/minute) until it exits the orifice after 180 seconds; then stop the piston. After another 120 seconds (total 300 seconds),
Perform a series of extrusions at different piston speeds and record the force required for each extrusion speed. The shear stress, shear rate and apparent melt viscosity are then calculated from this data. For any given value of shear stress,
The apparent melt viscosity of the polymer of Example 1 is lower than that of the polymers of Control Examples A and B, and thus the polymer of Example 1 is easier to process in the molding machine and to remove from the autoclave during manufacturing. is shown to be easier. Heat Distortion Temperature Heat Distortion Temperature (HDT) is the temperature at which a polymer is tested before it is tested.
Annealed at 100°C for 30 minutes and measured according to ASTM D-648. The heat distortion temperatures of the product of Control C and the product of Example 1 were measured and compared as follows: 66 psi stress 264 psi stress Control C 125°C 123°C Example 1 132°C 124°C This data is based on The tetrapolymer made from the PACM used in Example 1 (greater than 59% desired isomer) is shown to have a higher HDT compared to the polymer made from the PACM used in Control Example C.

Claims (1)

[Scope of Claims] 1 a. 60 to 90 mol % of isophthalic acid based on the total amount of acids present, b. 10 to 40 mol % of terephthalic acid based on the total amount of acids present, c. 98 based on the total amount of amines present. ~92 mol % of hexamethylene diamine, and d the lower limit of the mol % present is 2 mol % of the total amount of amine present and the upper limit is 1/11 of the mol % of a) present, and bis(p- At least 59% by weight of aminocyclohexyl)methane consists essentially of polycondensates formed from units of bis(p-aminocyclohexyl)methane, which are either trans-trans or cis-trans isomers. a polyamide, provided that the amounts of acids a) and b) together are about 100 mol % and the amounts of amines c) and d) are about 100 mol % together, and the polyamide has a temperature of 30,000 poise at 280°C. Polyamide resin for molding, which has a lower melt viscosity. 2. The moldable polyamide resin of claim 1, wherein the two components are present in the following amounts: a about 70 mol% b about 30 mol% c about 96.5 mol% d about 3.5 mol%.