This invention is concerned with blends of polyamideimides (PAD and polyetherimides (PEI) useful in the coating and mold¬ ing arts. More particularly the invention is concerned with a blend comprising by weight (a) from 5 to 95% of a polyamideimide comprising essentially chemically combined units of the formula

0

and (2) from 95 to 5% of a polyetherimide comprising essentially chemically combined units of the formula

where R is a member selected from the class consisting of

(a) the following divalent organic radicals:

and (b) divalent organic radicals of the general formula ^" _r

where X is -C 2 _2y ~' is a whole number equal to from 1 to 5 inclusive, and R~ is a divalent organic -radical selected from the class consisting of (a) aromatic hydrocarbon radicals having from 6-20 carbon atoms and halogenated derivatives thereof, (b) alkylene radicals and cycloalkylene radicals having from 2-20 carbon atoms, (c) ^c r ₂ -81 alkylene terminated polydiorgano- siloxanes, and (d) divalent radicals included by the formula.

where Q is a member selected from the class consisting of

_. o o

-0-, -C- ,-S-, -S-, and - C H - , ό ^{χ 2 χ} and x is a whole number equal to from 1 to 5, inclusive. 5 Polyamideimides are known to have good chemical resis¬ tance and moderate heat resistance. Although such polyamide¬ imides can be dissolved in suitable solvents for coating

O.

applications, such polyamideimides are quite difficult to mold and require excessive temperatures and pressures in the mold¬ ing cycle. Polyetherimides are known to have good high tem¬ perature characteristics and are more amenable to viable mold- ing cycles; however, it would be advantageous to upgrade the chemical resistance of these polyetherimides and reduce their cost for molding and coating applications.

We have unexpectedly discovered that blends of polyamide¬ imides of formula I and polyetherimides of formula II over a wide range can be made in which the properties of the blend show a marked average improvement over the properties of the components of these blends, and in some instances the improve¬ ment in properties are unexpected considering the proportion of either the polyamideimide or the polyetherimide used. By making the above-described blends, the utility for both thes'e members in the blend can be considerably expanded. In addition, by blending the polyamideimide with polyimides, products can be obtained which are lower in cost than is usually associated with the use of the polyetherimides alone without significant sacrifice (if any) in properties.

The polyetherimides which are employed in the present invention can be made in accordance with the disclosures and teachings in 0.S. patent 3,847,867 issued November 12, 1974 in the names of Darrell R. Heath and Joseph G. Wirth and assigned to the same assignee as the present invention. The polyamideimides employed in the practice of the instant in¬ vention can be made in accordance with the disclosures and teachings in ϋ.S patent 3,372,90 issued August 3, 1976.

-4-

By reference both these patents are made part of the disclosures and teachings of the instant application.

A preferred class of polyetherimides which are included by formula (II) are polymers consisting essentially of from about 2 to 5000 or more units and preferably from 5 to 100 units of the formula •

where

Included by the polyetherimides of formula II, are poly¬ mers consisting essentially of the following chemically combined units,

BU K t

and mixtures thereof, where R 1 and R2 are defined above.

The polyetherimides of formulas II-V can be made by effecting reaction between an aromatic bis(etheranhyάride) of the general formula,

and an organic diamine of the general formula,

VIII. H-NR^TIH. where R and R are as previously defined.

There can be employed from 0.95 to 1.05 mols of aromatic bis (etheranhydride) per mol of organic diamine. I-t is preferred to employ substantially equal molar amounts of bisanhydride and diamine■

The polyamideimides employed in the present invention (which can have from 10 to 5000 or more units of formula I) can be prepared from acyl halide derivatives of trimellitic an¬ hydride. The acyl halide derivative from trimellitic an¬ hydride (1,2,4-benzene tricarbox lic acid anhydride) having at least one acyl halide and that in the 4-ring position, include derivatives, such as the 4-acid chloride 1/4- and 2,4-ciacid

chloride. The bromide and other reactive halide derivatives are also suitable. The acyl halide derivative is reacted with an aromatic diamine having one or more aromatic rings and two primary amino groups corresponding to general formula VIII. In making the polyetherimides, there are employed from 0.95 to 1.05 mols of the auromatic dianhydride of formula VII per mol of the organic diamine of formula VIII. Preferably, one ^" can employ equal or lower amounts of the bisanhydride and diamine.

In making the polyamideimide, again one can employ from 0.95 to 1.05 mols of the trimellitic anhydride derivative of the formula, for example,

per mol of organic diamine of formula VIH, Preferably one employs substantially equal molar amounts of the trimellitic anhydride derivative of formula IX and the organic diamine.

Chain stoppers such as aniline or monσ-rorganic acid deri¬ vatives or monoanhydrides may be used in making either the poly¬ amideimide or polyetherimide. Generally either the polyetherimideor the polyamideimide ^" can be obtained by effecting the reaction between the chosen organic diamine and the particular dianhydride or monoanhydride in the presence of a dipolar aprotic organic solvent under ambient conditions to produce a polyamide acid. In both instances, upon further heating the polyamide acids convert to the imidized state comprising the units of formulas I and II.

°- ^Vι

Depending upon the solids content of the polyamide acid solution reaction can be completed in from 0.5 to 2 hours or more. Upon completion of the reaction, the solution can be cast on a sub¬ strate so that evaporation of the organic solvent occurs. By heating at temperatures of from 150-200°C or higher one converts the polyamide acid of each polymeric member of the blend to the polyimide state, so that the blend at this point has good-heat resistance, chemical resistance such as solvent resistance, and moldability if the desired use of these blends is in molding applications. Such blends are particularly useful as wire coat¬ ing enamels and impart solvent resistance and heat resistance properties to various substrates.

The aromatic bis(etheranhydride) of formula VTI shown in the above-mentioned U.S. patent 3,847,867, can be prepared from the hydrolysis followed by dehydration of the reaction product of the nitrosubstituted phenyl dinitrile and then reaction with a dialkali metal salt of a dihydric aryl compound in the presence of a dipolar aprotic solvent, where the alkali metal salt has the general formula

Alk - 0 0 - Alk where R has the meanings given above and preferably is the

2 same as R and Alk is an alkali metal ion. Various well known procedures can be used to convert the resulting tetranitriles to the corresponding tetracids and dianhydrides.

Included among the alkali metal salts of the above describe! dihydric phenols are sodium and potassium salts of the follow¬ ing dihydric phenols:

2,2-bis-(hydroxyphenol)propane;

2,4'-dihydroxydiphenylmethane;

bis-(2-hydroxyphenyl)-methane;

2, -bis-(4-hydro.cyphenyl)-propane hereinafter iden- as "bisphenol-A" or "BPA; "

1,1-bis-(4-hydroxyphenyl)-ethane;

1,1-bis-(4-hydroxyphenyl)-propane ,3-bis-(4-hydroxyphenyl)-pentane;

4,4'-dihydroxybiphenyl;

4,4'-d__hydroxy-3,3 ^• ,5,5'-tetramethylbiphenyl;

2,4-dihydroxybenzophenone;

4,4'-dihydroxydipheny1 sulfone;

10 2,4'-dihydroxydipheny1 sul one;

4,4'-dihydroxydiphenyl sulfoxide;

4,4'-dihydroxydipheny1 sulfide; etc.

Included by the organic diamines of formula VII are, for example,

15 m-phenylenediamine; p-phenylenediamine;

4,4'-diaminodiphenylpropane;

4,4'-diaminodiphenylmethane; benzidine;

20 4,4'-diaminodiphenyl sulfide;

4,4'-diaminodiphenyl sul one;

4,4'-diaminodiphenyl ether;

1,5-diaminoaphthalene;

3,3'-dimethyIbenzidine;

25 3,3'-dimethoxybenzidine;

2,4-diaminotoluene; 2,6-diaminotoluene;

2,4-bis (g-amino-t-butyl)toluene; bis(p-S-methyl-o-aminopentyl)benzene;

l,3-diamino-4-isopropylbenzene;

1,2-bis (3-aminopropoxy)ethane; m-xyl lenediamine; p-xyl lenediamine; - b-is(4-aminocyclohexyl)methane;

3-methylheptamethylenediamine;

4,4-dimethylheptame hylenediamine;

2,11-dodecanediamine;

2,2-dime hylpropylenediamine; ^-° octamethylenediamine;

3-methoxyhe_-amethylenediamine;

2,5-dimethylhexamethylenediamine;

3-methylheptamethylenediamine;

5-methylnonameth lenediamine; -5 l, -cyclohexanediamine;

1.12-octadecanediamine; bis(3-a_πinopropyl)sulfide;

N-methyl-bis(3-aminopropyl)a ine; heXamethylenediamine;

20 nonamethylenediamine; 2,6-diaminotoluene; bis-(3-aminopropyl) tetramethyldisiloxane, etc. The polyetherimide-polyamideimide blend can be reinforced with various particulated fillers such as glass fibers, silica, fillers, carbon whiskers, up to 50% or more, by weight, of the

25 total blend.

In order that those skilled in the art may better under¬ stand how the present invention may be practiced, the following examples are given by way of illustration and not by way of limitation. All parts are by weight unless otherwise indicated.

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EXAMP E 1 This example illustrates a method which has been used for the preparation of the polyetherimide. Other means for making such imides and use of various substituted ingredients such as diamino compounds or the dianhydride are described in the above-mentioned U.S. patent 3,847,867.

A mixture of 4,4'methylenedianiline (37.344 parts) and 2,3-bis[4-(2,3-dicarboxyphenoxy) henyl]propane dianhydride (100 parts) , orthodichlorobenzene (1300 parts) and toluene (50 parts) was stirred and heated to reflux for five hours under a nitrogen atmosphere. In the course of the reaction, water formed was removed by azeotropic distillation. Upon cooling, the reaction mixture was poured into me hanol to isolate the polymer. The yield was 134.7 parts. The intrinsic viscosity was 0.41 dl./g. in dimethylformamide. The glass tran¬ sition temperature was 237 ^β C. as determined by thermal optical analysis. The elemental analysis found was: C, 77.8%, Ξ, 4.5%; N, 4.1%. Calculated for (C ₄₄ H ₃₀ N ₂ θ _g ) ^• is C, 77.4%; H, 4.4%; U, 4.1%.. By this method of preparation a polyetherimide is obtained having the formula

where n is a positive integer greater than 1.

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EXAMPIiΞ 2 A polyamideimide used in making the blends of our inven¬ tion can be prepared in accordance with the disclosures and teachings in the aforesaid U.S. patent 3,573,260. More particularly, following the directions of this patent (Example 1 ⁾ , a reaction vessel equipped with a nitrogen purge is charged with 6,055 parts dimethylacetamide and 1,670 parts ethylene dianiline

The mixture is stirred for about 10 minutes after 1,775 parts of the 4-acid chloride of trimellitic anhydride (formula IX) is added over a period of 4 hours while maintaining a tem¬ perature of around 50 ^β C throughout the addition of the tri¬ mellitic anhydride acid chloride. The mixture is then heated at 50°C for an additional 2-4 hours after which the resulting polymer can be precipitated by well known means. The polymer is advantageously washed to remove hydrochloric acid and then centrifugred to remove excess water. Thereafter the polymer is dried, e.g., with a rotary drum drier at about 150°C.,to give _a polyamideimide of the formula

where m is a whole number greater than 1

EXAMPLE 3 In this example, a polyetherimide (PEI) of formula XI (prepared as in Example 1) , and a polyamideimide (PAI) of formula XI-U (prepared as in Example 2) were mixed in various proportions by dissolving the two polymers in a sufficient amount of N-methylpyrrolidone at about 150 ^β C. This yielded a clear solution which when cooled to room temperature gave a homo¬ genous solution. Evaporation of the solvent .yielded a clear yellow film which was difficult to scratch. In other tests, the two solid polymers were blended at 315 ^β C for ten minutes and thereafter the polymer mixture was cooled to room tem¬ perature and compression-molded at 320-330 ^β C. for 10 minutes into thin sheets. The following Table I shows the physical properties of mixtures of the polymers blended at the elevated temperatures and then molded using varying amounts of either the polyetherimide or of the polyamideimide.

Table I

Parts by Weight of

Polymer Ingredients Tensile Strength, Psi Percent Elongation

PEI PAI Yield ultimate ultimate

100 0 12,300 11,400 19.3%

75 25 12,500 11,100 20.9%

60 40 14,600 .13,300 16.8%

50 50 - 13,700 -

25 75 11,800 10,800 15.5%

0 100 Difficult -co Mold

It will be apparent from an examination of Table I that with the exception of the test which was carried out on the polyamideimide itself which was not moldable at the specified conditions, unexpectedly the tensile and elongation

properties of the blends were quite close despite the varying amounts of- polyetherimide and polyamideimide present in the blend. It is particularly unexpected to find that whereas the 100% polyamideimide was not moldable under the conditions of this test, all the other blends, even those having significant amounts of the polyamideimide were moldable and in fact the physical properties were quite comparable to those of the molded 10C% polyetherimide. Finally, it is found that in the case of each blend, the solvent resistance, whether in film form- or in the molded state, is enhanced.

EXAMPLE 4 2.1 gm of trimellitic acid chloride (TMAC) and 1.98 gm of 4,4'-methylene dianiline of formula XII was mixed with 15 cc of N-methylpyrrolidone. After stirring, this mixture exotherrtsd to 59 ^β C. to give a clear polymeric amic acid amide identified as solution A.

In another reaction vessel 5.2 g of 2,2-bis [4-(2,3—dicar- boxyphenoxy) phenyl] propane a.nd 1.98 gm of methylenedianiline were mixed with 15 cc of N-methylpyrrolidone 'to yield after exother ing to 64°C.# a clear polymeric amic acid amide iden¬ tified as solution B.

9.5 gm of polymer solution A was mixed with 11.1 gms of solution B at room temperature and the mixture was stirred until it was homogeneous. From this solution blend a film was cast at 280-300°C. yielding an imidized polymer film containing blends of polyamideimide and polyetherimide which had good abrasion resistance.

-14- EXAMPLE 5

2.1 gm of TMAC and 2.48 gm of 4,4'-diaminodiphenyl sul one in 15 cc N-methylpyrrolidone was stirred to yield after exo¬ therming to 38 ^β C, a clear polymeric amic acid amide identified as solution A.

In another reaction vessel, 5.2 g of 2,2-bis[4-(2,3dicar- boxyphenoxy)- phenyl] propane and 2.48 gm of the same diamino¬ diphenyl sulfone were mixed with 15 cc N-methylpyrrolidone, to yield after exotherming to 37 ^β C. , a clear polymeric amic acid amide identified as solution B.

While stirring, 9.8 -gm of polymeric solution A was blended with 11.4 gms of solution B at room temperature until the mixture was homogeneous. From this solution blend a film was cast at 280-300°C. yielding an imidized polymer film contain¬ ing blends of polyamideimide and polyetherimide having good abrasion resistance.

EXAMPLE 6

2.1 gm of TMAC and 2.0 gm of 4,4'oxydianiline in 15 cc of N-methylpyrrolidone was stirred to yield, after exotherming to 63°C, a clear polymeric amic acid amide identified as solution A.

In another reaction vessel, 5.2 g of 2,3-bis [4-2,3-dicar- boxyphenoxy) phenyl] propane and 2.0 gm of 4,4 'oxydianiline were stirred in 15 cc N-methylpyrrolidone to yield, after exotherming to 61 ^β C, a clear polymeric amic acid amide identified as solution S.

9.6 gm of polymeric solution A was blended with stirring with 11.1 gms of polymeric solution B at room temperature until the mixture was homogeneous. From this solution blend a film was cast at 230-300 ^β C. yieldin an

-15-

imidized polymer film containing blends of polyamideimide and polyetherimide having good abrasion resistance.

EXAMPLE 7 2.1 gm of TMAC and 1.08 gm of m-phenylenediamine in 15 cc N-methylpyrrolidone was stirred to yield, after exotherming to 43 ^β C, a clear polymeric amic acid amide identified as solution A.

In another reaction vessel, 5.2 g of 2,3-bis[4-(2,3-*ϊicar- boxyphenoxy) phenyl] propane and 1.08 gm of m-phenylenediamine were stirred in 15 cc of N-methylpyrrolidone, to yield after exotherming to 41 ^σ C, a clear polymeric amic acid amide, iden¬ tified as solution B.

9.1 gm of polymeric solution A was blended with stirring with 10.7 gms of polymeric solution B at room. temperature until the mixture was homogeneous. From this solution blend, a film was cast at 280-300°C. yielding an imidized polymeric film containing blends of polyamideimide and polyetherimide having resistance to abrasion.

EXAMPLE 8 2.1 gm of TMAC and 1.08 gm m-phenylenediamine placed in 15 cc of N-methylpyrrolidone was stirred to yield, after exotherming to 43 ^β C, a clear polymeric amic acid amide iden¬ tified as solution A.

In another reaction vessel, 5.2 g of 2,2-bis[4-(2,3-dicar- boxyphenoxy) phenyl] propane and 1.98 gm of 4,4'-methylenedi¬ aniline were stirred in 15 cc N-methylpyrrolidone, to yield after exotherming to 6 "C., a clear polymeric amic acid amide identified as solution B.

9.1 gms of polymeric solution A was blended with stirring with 11.1 gms of polymeric solution B at room temperature until the mixture was homogeneous. From this solution blend, a film was cast at 280-300°C. yielding an imidized polymer film containing blends of polyamideimide and polyetherimide.

The Tg's of the blends in Examples 4-8 (with the solvent removed) were determined as were the Tg's for the 100% PEI and 100% PAI described in Example 7. The following Table II showed the results of these tests. It will be noted from Table II that unexpectedly the Tg's, as exemplified by the results in Example 7, instead of being an average of the Tg's of the homopolyraers were considerably below the Tg's of the homo- polymers indicating the unexpected and unobvious results obtainable by blending polyetherimides with polyamideimides. The reduction in Tg's (which measures the degree of softening) improves the moldability of the blends of the instant invention.

Table II

Example Number Blend _&

4 203 ^β C

5 161 ^β C

6 -

7 147 ^β C

7a (100% PEI) 220°C

7b (100% PAI) 241°C

8 203 ^β C.

It will of course be apparent to those skilled in the art that in addition to the diamino compounds used in making the above blends, other diamino compounds, many examples of

which have been ^" recited previously, can be used instead. In the same manner, in addition to the .bisphenol-A dianhydride employed in the examples in this application. Other dianhydrides, many examples of which have been given above, can be employed to make other types of polyetherimides. Finally, the pro¬ portions of the polyamideimide and the polyetherimide in the. blend can be varied widely within the range previously described without departing from the scope of the invention.

In addition to the two resins comprised in the blend above, other polymers and resins in amounts ranging from 1 to 50% or more, by weight, based on the total weight of the blend of polyamideimide and polyetherimide resins may also be used. Among such polymers may be added, for instance, polyolefins, polystyrene, polyphenylene oxides, such as shown in ϋ.S. patent -3,306,875, epoxy resins, polycarbonate resins, such as shown in ϋ.S. patent 3,028,365, silicone resins, polyarylene poly- ethers such as shown in U.S. patent 3,329,909, etc. many of which are well known in the art.

The compositions of the present invention have application in a wide variety of physical shapes and forms, including their use as films, molding compounds, etc. The heat stability and resistance to deformation at elevated temperature, while at the same time-retaining their properties at elevated tem¬ peratures in the imidized state, make these compositions quite useful. When used as films or when made into molded products, these polymers including the laminated products prepared there¬ from not only possess good physical properties at room tem¬ perature but they retain their strength and excellent response to workloading at elevated temperatures for long periods of

-18-

time. These blend compositions resist fusion when exposed to elevated temperatures, for extended periods of times while still retaining an exceptionally high proportion of their room temperature physical properties. Films formed from the polymeric blends of this invention may be used in applications where films have been used pre¬ viously. They serve effectively in an extensive variety of wrapping and packaging applications. Thus, the compositions of the present invention can be used in automobile and aviation applications for decorative and protective purposes, and as

.high temperature electrical insulation for motor slot liners, in transformers, and as dielectric capacitors.

Alternatively, solutions of the curable compositions herein described can be coated on electrical conductors such as copper, aluminum, etc. and thereafter the coated con¬ ductor can be heated at elevated temperatures to remove the solvent and to effect curing of the resinous composition there¬ on. If desired, an additional overcoat may be applied to such insulated conductors including the use of polymeric coat- ings, such as polyamides, polyesters, silicones, polyvinyl- formal resins, epoxy resins, polyimides, polytetrafluoro- ethylene, etc.

__ Applications which recommend these resins include their use as binders for asbestos fibers, carbon fibers, and other fibrous materials in making brakelinings. In addition, grind¬ ing wheels and other abrasive articles can be made from such resins by incorporating abrasive grains such as alundum, carborundum, diamond dust, etc., and shaping or molding the

mixture under heat and pressure to obtain the desired config¬ uration and shape for grinding and abrasive purposes.