DE2458733B1 - Increasing viscosity of (co)polyamides - using bis-oxazoline and cationic catalyst or bis-oxazoline salt, avoiding melt instability - Google Patents

Abstract

Increased viscosity is imparted to aliphatic(co)polyamides(I), produced by hydrolytic cpolymerisation, opt. in the presence of 0.3-1.2 wt. % mono-or-dicarboxylic acid as viscosity stabiliser, by dispersing homogeneously in the melt (a)1-15, pref. 5-10 wt. % bisoxazoline (II) and 0.005-1, pref. 0.01-0.5 wt. % cationic catalyst (III) or (b) 1-15 pref 5-10 wt. % salt (IV) of (II), prepd. by alkylating (II) all amts. being w.r.t. (I). (IV) pref. is a reaction prod. (IVa) of 1 mole 2,2'-(1,4-phenylene)-bis-(2-oxazoline) with 2 mole Me2SO4 Method is used for the treatment of (I) with 6-12 C units, e.g. polyamide 6;6,6;8;6,10;11;12; and 66,12; and copolyamide 6/6, 6/12;6/6, 12/12;6/12;6/6, 12; and 11/12; esp polylaurolactam(polyamide 12) and its copolymers. A highly viscous polyamide can be produced simply from a polyamide of low viscosity without costly condensn. In the solid state and without familiar disadvantages, such as melt instability or incompatibility.

Description

Examples include: 2,2'-methylene-bis- 12-oxazoline, 2,2'-tetramethylene-bis- 12-oxazoline, 2,2'-decamethylene-bis- 12-oxazoline, 2,2 '- (1,4-cyclohexyl) -bis- 12-oxazoline, 2,2'-p-phenylene-bis-12-oxazoline, 3.7'-m-phenylene-bis-12-oxazoline, 2,2'-p-phenylene-bis- (5-methyl-12-oxazoline), 2,2'-m-phenylene-bis- (5-methyl-12-oxazole in), 2,2'-tetramethylene-bis- (5-ethyl- 12-oxazoline), 2,2'-decamethylene-bis- (5-methyl- 12-oxazoline).

It is advantageous to use: 2,2'-tetramethylene-bis-12-oxazoline, 2,2'-decamethylene-bis- 12-oxazoline, 2,2'-p-phenylene-bis- 12-oxazoline and 2,2'-p- Phenylene bis (5-methyl-12-oxazoline).

The bisoxazolines can be prepared according to the in Liebigs Ann. Chemie (1974), 996, or in DT-OS 21 27 776 and 21 35 644 described Process by reacting a dinitrile with amino alcohols.

Sulfuric acid can be used as cation-active catalysts, Phosphoric acid, organic sulfonic acids, such as. B. p-toluenesulfonic acid, benzenesulfonic acid, 1- or 2-naphthalenesulfonic acid, perchloric acid, boron trifluoride or its addition compounds, z. B. ethers, hydrohalic acids, tin chloride, aluminum chloride. Further esters of strong acids such as B. alkyl sulfates or alkyl sulfonates, Alkyl halides, insofar as they can react with amines with quaternization and those compounds which under the reaction conditions, optionally partially, can pass into the substances mentioned, such. B. p-nitrophenyl diazonium fluoroborate or ammonium sulfate. Salts or salt-like compounds of the bisoxazolines with the above Substances also prove to be effective catalysts and can also be isolated Connections are used.

In general terms, the cation-active catalysts can be used which are suitable for the polymerization of 12-oxazolines (cf.

DT-PS 12 06 585).

As already mentioned, the bisoxazolines or the salts of the bisoxazolines in amounts of 1 to 15, preferably 5 to 10 percent by weight and the cation-active Catalysts with the bisoxazolines in amounts of 0.005 to 1, preferably 0.01 up to 0.5 percent by weight, based in each case on the polyamides used.

The bisoxazoline salts are advantageously used if this is undesirable is to have an acidic catalyst in the polyamide. Activated by salt formation Bisoxazolines can be obtained in a simple manner by taking the bisoxazoline in a suitable solvent such as methylene chloride, chloroform, tetrahydrofuran, Diethyl ether, dimethylformamide or dimethyl sulfoxide, with twice the molar amount an alkylating agent. The salt precipitates out of the solvent or can be obtained therefrom after the solvent has been separated off.

The aforementioned cation-active catalysts are used as alkylating agents suitable, but it is advantageous not to use the free acids mentioned, but the esters of these acids, e.g. B.

Alkyl sulfates, such as dimethyl sulfate, diethyl sulfate, alkyl halides, such as methyl iodide, ethyl iodide, methyl bromide, ethyl bromide or trialkyloxonium fluoborate.

Dimethyl sulfate is particularly advantageous as it is a stable salt of bisoxazoline, which does not cause discoloration in the polyamide.

Suitable aliphatic polyamides are those with 6 to 12 carbon atoms in the basic module; Polyamide 6, polyamide 6,6, polyamide 8, and polyamide may be mentioned here 6, 10, polyamide 11, polyamide 12, polyamide 6, 12, and their mixed polyamides, such as polyamide 6/6, 6/12, polyamide 6/6, 12/12, polyamide 6/12, polyamide 6/6, 12, polyamide 11/12. In particular, polylaurolactam (polyamide 12) and its mixed polyamides are used.

The viscosity-increasing agents to be used according to the invention are added to the polyamides in the melt. This can be done in the polymerization reactor after the end of the polycondensation under an inert gas atmosphere or afterwards in an extruder.

However, it is also possible to produce so-called masterbatches, by using previously prepared mixtures of polyamide and viscosity-increasing agent, which the polyamide and the aggregates in a weight ratio of 90:10 to 60:40, in particular 85:15 to 75:25, in appropriate amounts either in the Brings melt of the polyamide in the polymerization reactor or in the extruder.

The polyamides should be in the form of a homogeneous melt. Suitable processing temperatures for the addition of the viscosity-increasing agents are therefore generally included 180 to 300, preferably 200 to 280 "C above the melting point of the polyamide. In the case of polylaurolactam, a temperature between 230 and 280 "C has proven to be advantageous proven. However, it is also possible to use a low-temperature melt and optionally heating them after adding the viscosity-increasing agents.

The polyamides or mixed polyamides are produced in a known manner Way by hydrolytic polymerization in the presence of 2 to 10 percent by weight Water at elevated pressure and at temperatures between 260 and 340 "C, with intermittent is removed by reducing the pressure of the condensation water. Usually be the well-known viscosity stabilizers made from mono- or

Dicarboxylic acids such as acetic acid, adipic acid, benzoic acid, dodecanedioic acid used in amounts of 0.3 to 1.2 percent by weight. Catalysts such as phosphoric acid or other phosphorus-containing compounds can also be used. you However, addition in the polycondensation is not absolutely necessary. A suitable one Procedure for determining the viscosity during the polycondensation, d. H. before the addition of the viscosity-increasing additives is in Angew. Macrom. Chem. 34 (1973), Pp. 135 to 152.

Contrary to the state of the art, the method according to the invention permits increasing the viscosity of polyamides, which in the presence of larger amounts Viscosity stabilizers (regulators), such as B.

Carboxylic acids.

Examples The solution viscosity IIrel of the examples was determined in m-cresol at 25 "C and a concentration of 0.5 g / 100 ml.

Example 1 polylaurolactam, which in the presence of 0.8 percent by weight Adipic acid has been produced with an adjusted solution viscosity llrel of 1.50, adjusted according to 1. c. Applied Macrom. Chemistry, were taking at 250C Addition of 5 percent by weight of the salt from 1 mol of 2,2 '- (1,4-phenylene) -bis- (2-oxazoline) and treated 2 moles of dimethyl sulfate with stirring for 1 hour. The polylaurolactam obtained possesses a solution viscosity #rel of 1.77, which is an increase of Q27 units is equivalent to.

Example 2 A polylaurolactam was treated in the same way with an initial viscosity of #rel VOll 1.80.

The increase was 0.29 units, giving a final viscosity of 2.09 is equivalent to.

Example 3 A polylaurolactam (polyamide 12) with an initial viscosity 1free of 1.50 was obtained in the same way with 5 percent by weight of 2.2 '- (1,4-phenylene) -bis- (2-oxazoline) and 0.1 weight percent p-toluenesulfonic acid. The increase in viscosity was 0.2 units, the final viscosity accordingly llrel 1.70.

Example 4 A polycaprolactam (polyamide 6) with an initial viscosity of 1.60 was with 5 percent by weight of the salt from 1 mol of 2,2'-tetramethylene-bis- (2-oxazoline) and 2 mol dimethyl sulfate in the same way treated. The viscosity increase was 3 On20 units, corresponding to a final viscosity of SIr.l 1.80.

Example 5 A polyundecanoic acid amide (polyamide 11) with an adjusted Solution viscosity (1. c. Angew. Macrom.

Chemistry) of 11rel 1.55 was in the same way with 5 weight percent of the salt of 1 mole of 2,2 '- (1,4-phenylene) bis (2-oxazoline) and 2 moles of dimethyl sulfate treated. The increase in viscosity was 0.24 units, the final viscosity accordingly lirel 1.79.

The following comparative example 1 shows that when using monooxazolines and the cation-active catalysts do not increase in viscosity.

Comparative Example 1 A polylaurolactam with an adjusted Starting viscosity of 1.50 was with 5 weight percent 2- (4-methylphenyl) -2-oxazoline and 0.05 percent by weight p-toluenesulfonic acid treated in the same way at 250 ° C. The final viscosity was 11rel 1.47.

The following comparative example shows that bisoxazolines alone also do not have a viscosity-increasing effect.

Comparative Example 2 A polylaurolactam with an adjusted Solution viscosity of SIrel 1.50 with 5 weight percent 2.2 '- (1,4-phenylene) -bis- (2-oxazoline) treated in the same way at 2500 C alone. The final viscosity was the same as that Initial viscosity.

Claims (3)

Claims: 1. Method for increasing the viscosity of aliphatic Polyamides or mixed polyamides, which optionally by hydrolytic polymerization in the presence of 0.3 to 1.2 percent by weight of mono- or dicarboxylic acids as viscosity stabilizers have been produced, d a -characterized that one in the melt, each based on the polyamide, a) 1 to 15 percent by weight bisoxazoline and 0.005 to 1 percent by weight of a cationic catalyst or b) 1 to 15 percent by weight a separately prepared salt of bisoxazoline, which by reacting the Bisoxazoline obtained with an alkylating agent is homogeneously distributed. 2. The method according to claim 1, characterized in that in of the melt, based in each case on the polyamide, a) 5 to 10 percent by weight bisoxazoline and 0.01 to 5 percent by weight of a cationic catalyst or b) 5 to 10 percent by weight of a separately prepared salt of bisoxazoline, which has been obtained by reacting the bisoxazoline with an alkylating agent, homogeneously distributed. 3. The method according to claims 1 and 2, characterized in that that the reaction product of 2,2 '- (1,4-phenylene) -bis- (2-oxazoline) is used as the salt of bisoxazoline used with twice the molar amount of dimethyl sulfate. It is known to produce high molecular weight polyamides by in hydrolytic melt condensation in the absence of viscosity stabilizers, wiexcarboxylic acids or amines, or only in the presence of small amounts, e.g. B. 0.1 up to 0.2 percent by weight, works (Kunststoffhandbuch, Vol. VI, Polyamide (1966), P. 19 ff.). However, polyamides produced in this way are unstable in the melt and consequently change their molecular weight during processing when the equilibrium water content is not set precisely. It is known that hydrolytic polycondensation in In the presence of larger amounts of the viscosity stabilizers, they are no longer post-condensable Polyamides with only relatively low molecular weight, expressed by the relative Solution viscosity l / rel - 1.5 (measured in m-cresol at 25 "C and a concentration of 0.5 g / 100 ml). Molding compounds which are to be extruded during processing however, have values of Ire from about 1.7 to 2.2. It is also known to produce high molecular weight polyamides by the hydrolytic melt condensation in the presence of phosphorus compounds takes place and then post-condensed in the melt or below the melting point. Polyamides produced in this way also prove themselves during processing as unstable (US-PS 35 51 548 and US-PS 35 58 569). From the published documents of the Japanese patent application 41 744/1972 is known to increase the melt viscosity or the molecular weight Use polyacrylamide. However, the addition of polymeric compounds has the Disadvantage that, because of their incompatibility, little usable molding compositions are obtained will. The task is without the well-known, complex post-condensation in the solid state in a simple way from a low-viscosity polyamide to a high-viscosity one Producing polyamide, which has the disadvantages of the prior art. z. B. the Instability in the molten state or intolerance symptoms, no owns. The problem is solved if one is involved in aliphatic polyamides or mixed polyamides, which optionally by hydrolytic polymerization in Presence of 0.3 to 1.2 percent by weight of mono- or dicarboxylic acids as viscosity stabilizers have been produced, in the melt, in each case based on the polyamide, a) 1 up to 15 percent by weight bisoxazoline and 0.005 to 1 percent by weight of a cationic Catalyst or b) 1 to 15 percent by weight of a separately prepared salt of the bisoxazoline, which is obtained by reacting the bisoxazoline with an alkylating agent has been obtained, distributed homogeneously. It is advantageous to use 5 to 10 percent by weight of the bisoxazoline and 0.01 to 0.5 percent by weight of the cation active catalyst, or 5 to 10 Weight percent of the salt of bisoxazoline. Compounds of the general formula are used as bisoxazolines used in which R1 is a hydrogen atom or a straight-chain or branched alkyl radical or an optionally substituted cycloalkyl radical with 1 to 9 carbon atoms or an aralkyl radical with 7 to 12 carbon atoms or an optionally substituted aryl radical with 6 to 10 carbon atoms and R2 is a straight-chain or branched alkyl radical or a represents an optionally substituted cycloalkyl radical having 1 to 9 carbon atoms or an aralkyl radical having 7 to 12 carbon atoms or an optionally substituted aryl radical having 6 to 10 carbon atoms.