CA2039136A1

CA2039136A1 - Amorphous polyamide compositions containing a carbon black compound exhibiting improved melt flow

Info

Publication number: CA2039136A1
Application number: CA 2039136
Authority: CA
Inventors: G. Fred Willard; Deborah Lynn Mendel
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1991-01-10
Filing date: 1991-01-10
Publication date: 1992-07-11

Abstract

ABSTRACT OF THE DISCLOSURE
Amorphous polyamide compositions containing a small amount of a carbon black compound therein exhibit increased melt flows. These compositions are particularly suitable for producing fiber reinforced composites.

Description

2 0 3 9 ~ 3 6 CARBON BLACK COMPOUND EXHIBITING IMPRO~ED MELT FLOW
Deborah L. Mendel G Fred Willard BACKGROUND OF THE INVENTIQN
Field of th~ InventiQn The present invention relates to amorphous polyamides and reinforced articles made therefrom, and, more particularly, relates to compositions con~aining amorphous polyamides and a carbon black 5 compound and reinforced artioles made from such compositions.
DESCRIPTION QF RELAIED ~RI
Carbon black is a known additive to polymers.
Specifically, carbon black has been added as a colorant and filler in variou~ resin compositions. In addition, carbon black has been used to improYe the conductive properties of some polymer compositions.
Generally, the addition of carbon black increases the viscosity o~ the polymeric composition; see for example K. Lakdawala and R. Salevey, "Rheology of Polymers Containing Carbon Black," PQ1Vm. Enq~ Sci..
27(14~, p. 1035 (1987). These inc~eases in viscosi~y upon addit~on of carbon black are also noted in Datta, U.S. Patent 4,299,736. Datta discloses that the 20 addition of carbon black a~ 15 weigh~ percen~
increases the melt viscosity of the polyvinyl chloride composition, but this increase in viscosity is reduced when carbon black compounds treated wi~h a fatty acid chloride are present in the poly~inyl chloride compssition. In Datta, the melt viscosi~y of the compositions set forth in the examples containing fatty acid chloride treated carbon black compound is lower than the melt viscosity of a comparison composition containing untreated carbon black cvmpounds, but shows ~ O 3 9 ~ ~ ~

little or no improvement over the melt viscosities of the pure polyvinyl chloride resin.
Lakdawala d;scloses that the addition of a carbon black compound to a high molecular weight polystyrene 5 resulted in a composition that exhibited a viscosity lower th~n that of the neat polymer at high shear rates and at carbon loading levels of 5 and 10 weight percent based on the total weight of the composition, but further discloses that reduced viscosities were not observed for several other polymers, specifically, a low molecular weight polystyrene and a poly~butyl methacrylate).
In a similar study Lakdawala (K. Lakdawala and R.
Salovey, "Rheology of Copolymers Containing Carbon Black," Polym. Enq~ ~ci.. 27~14) p. 1043 (1987) at p.
1044, 1045) indica~ed that the addition of certain carbon black compounds to certain copolymers of styrene and butyl methacryl ate exhibited lower viscosities than that of the neat copolymers under par~icular high shear rates and carbon loading levels.
Lakadawala's specific disclosures of impro~ed melt viscosities appear to be limited to examples of weight loadings of 5 percent and in some cases 10 percent and 20 percent.
Whlle the art teaches that the addition of 5, 10 and 20 weight percent of certain carbon black compounds under specifie conditions to a high molecular weight polystyren~ and to two types of copolymers of styrene and butyl methacrylate results in reduced viscosities the art also illustrates a number of conditions and compositions for which this reduced viseosi~y effect was no~ observe~ upon the addition of a carbon black ccmpound ~o ~arious polymers and copolymers. These references do not show how to reduce the mel~ Yiscosi~y of amorphous . ~ . .

2 ~ ~ 9 1 3 6 polyamides and more speci~ically do not suggest that small amounts of carbon black compounds should be added to amorphous polyamides to reduoe ~he viscosity thereof. Additionally, none of these references indicate that it is desirous to add amounts smaller than 5 weight percent to amor~hous polyamides to obtain reduced viscosities over the viscosities of the neat amorphous polyamide resin.
Padron (Al~onso J.C. Padron, "Influence of Additives on Some Physical Properties of High Density Polyethylene-I-Commercial Antioxidants", E~r. PQ1 Vm .
J. vol. 23, No. 9 p. 723 (1987) at p. 725.) discloses tha~ the addition of 1 percent by weight of a carbon black compound to a high density polyethylene results lS i n a composition that exhibits a melt flow index greater than the melt flow index of nea~ high densi~y polyethylene. Figure 5 of the Padron article indica~es that this increased melt flow index is no~
achieYed at concentrations of carbon black substantially above or below 1 weight percent. Padron does not teach or suggest that the addition of small amounts of a carbon black compound amorphous polyamides will result in improved melt flow properties thereof, and more specifically does not teach that the addition of small amounts o~ carbon black compound to amorphous polyamides will result in improved flow properti~s at low shear rates.
Amorphous polyamides, such as Nylon 6IT, are known. However, many amorphous polyamides, especially highly aromatic amorphous polyamides, exhibit higher melt Yiscosities ~han are desired for processiny thereof and for producing reinforced artioles .

~ ~3 ~ ~ 3 6 therefrom. Therefore, a need exists ~or amorphous polyamide compositions having reduoed melt viscosities.
A~cordingly, one objective of the present invention is to provide amorphous polyamide compositions having reduced melt viscosities.
SU ARY OF THE INV~NTIQ~
The present i nventi on provi des amorphous polyamide compositions having reduced melt viscosities. The compositions contain ~i) an amorphous polyamide resin and (ii) a oarbon black compound. The carbon black compound is preferably present in the composition at a level of 0.05 percent to 2.0 percent by weight based on the total combined 15 weight of the amorphous polyamide resin ànd carbon black compound. The carbon black compound is primari ly made up of carbon black particles having particle diameters of preferably less than 320 millimicrons. This composition is useful as an injection molding composition and as a resin matrix for the production of fiber reinforced composites.
~ETAILED DESCRIPTI~N OF T~E~ ENTION
This i nYenti on relates to amorphous p31yamide composit~ons comprising (i) a carbon black compound at Z5 a level of from 0.05 percent to 2.0 percent by weight based on the total combined weight of the amorphous polyamide resin and the carbon black compound. The present invention also involves fiber reintorced articles made from the amorphous polyamide oomposition and reinforcing fibers.
Amorphous polyamides are noncrystalline ngsins which do not exhibit a distinct melting poinkO
Examples of amorphous polyamides are Nylon 6,I,T and polyamides derived from ~oluenediamine and a - ~
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dicarboxylic acid; Nylon 6,I; polymers derived ~rom meta-xylenediamine, and isophthalic acid, polyamides derived from bis(para-aminocyclohexyl)methane and disarboxylic acids; polyamides deri ved from 2,2,3-trimethylhexamethylene diamine and terephthalic acid; and polyamides derived from isophthalio acid and bis(4-amino-3-methylcyslohexyl)methane. The preferred amorphous polyamide for the present invention is derived from toluenediamine and either an isophthalic acid, a mixture of isophthalic acid and terephthalic acid, or a mixture of isophthalic acid and aliphatic dicarboxylic acid, and generally exhibits high melt viscosities which makes it desirable to add the carbon black compound of the resent invention to reduce the 15 melt viscosity of the polyamide composition.
Polyamides may be obtained either by reacting a diamine with a dicarboxylic acid or by reacting a diamine with a diester of the dicarboxylic acid.
The amorphous polyamide of the composition is ~o prefera~ly present at a level of from 98 percent to 99.95 percent by weight based on the combined total weight of the amorphous polyamide and the carbon black compound, more preferably is present at a level of from 99 ts 99.8 percent by wei~ht thereof, and most preferably is present at a level of about 99.5 percent by weight thereof.
Carbon black compounds are finely divided carbonaceous pigments which can be produced by the incomplete combustion or thermal cracking of hydrocarbons. Suitable types of carbon black compounds for the present invention inelude furnaee black, thermal black and channel black. The carbon black compound for the present invention is made up of carbon black particles having diameters of at most 320 millimicrons and preferably particle diameters of from - : ~, 2 ~ ~ ~ 1 3 ~
08C~!04973 5 millimicrons to 320 millimicrons, more preferably particle diameters of from 10 millimicrons to 150 millimicrons, most preferably with particle diameters of about 17 millimicrons. The preferred carbon black S compound for the present invention is a furnace carbon black with a particle diameter of 17 millimicrons, density of 15 pounds per cubic foot, surface area of 210 square meters per gram, an oil absorption rate of 75 cubic centimeters per 100 grams, and is available o from Cabot Corporation under the commercial name Monarch 800. The ~arbon black compound is preferably present at a level of from 0.05 percen~ to 2.0 percent by weight based on the total weight of the amorphous polyamide resin and carbon black compound, more preferably present at a level of from 0.2 percent to l.0 percent by weight thereof, and most preferably present at about 0.5 percent by weight thereof.
The compositions comprising an amorphous polyamide resin and a small amount of carbon black 20 compound exhibit reduced viscosities and increased melt flows compared tQ ~hat of the pure amorphous polyamide resin. The amorphous polyamide compositions having increased melt flow are ~i) easier to process, (ii) useful for producing injection molded articles, and (i~) useful for producing glass ~iber reinforced amorphous polyamide composites.
The present invention is suitable for forming a fiber-reinforced composition comprising an amorphous polyamide, a carbon black compound and fiber 30 reinforcements. Suitable reinforcing fibers for the present i nventi on i ncl ude 9l ass fi bers, mi neral ~ibers, long glass fiber ma~, carbon fibers and metal fibers. The reduce~ melt viseosi~ies of ~he compositions make it easier ~o produce fiber 35 reinforced composi~e ar~icles having long fiber mats th~rei n.

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The present invention is particularly useful for forming fiber reinforced composites comprising an amorphous polyamide resin, a carbon black compound and a long glass fiber mat. The fiber mat is preferably 5 present at a level of from 20 to 60 weight percent based on the combined total weight of the amorphous polyamide, carbon black compound and long glass fiber mat. The pref~rred fiber mat for the present invention is a glass fiber mat of woven or non-woven gl~ss fiber strands or glass fiber filaments. The glass fiber mat is a porous, light weight material and may have a thickness of from 10 to 150 mils and a weight of from 0.1 to 5 ounces per square foot. The lower melt viscosity of the carbon black containing amorphous polyamide composition containing carbon black makes it easier to produce long fiber mat reinforced amorphous polyamide composites~ Reduced melt viscosi~y and increased melt flow are desired characteristics for the amorphous polyamide 20 compositions used to make the composites since high levels of flow of the amorphous polyamide compositions between and among the fibers in the glass fiber mat is necessary to completely fill the material and produce fiber reinforced articles having high levels of 2s strength.
The following examples are presented by way of illustration of the present invention and not by way of limitation.

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Z ~ 3 9 1 3 6 DES~RIPTIQN OF EX~MP~ES IN TABLE 1 An amorphous polyamide WdS derived from the reaction products of a diamine and a dicarboxylic acid. The diamine was a mixture of 70 mole persent of toluenediamine and 30 mole percent of hexamethylenediamine based on the total moles of diamine. The diaryl ester of the dicarboxylic acid was employed. The diaryl ester was a mixture of 75 lC mole percent of diphenyl isoph~halate and 25 mole percent of diphenyl terephthalate based on the total moles of diarylester of dicarboxylic aeid.
The sarbon black compound used was a furnace black grade having surface area of 25 square meters per gram, an oil absorption rate of 72 cubic centimeters per 100 grams, particle diameters of 75 millimicrons and a d~nsity of 18 pounds per cubic foot. The carbon black compound was obtained from Cabot Corporation under the commercial name of Monarch 120.
In Examples 1 ~o 5 the amorphous polyamide was compounded with various loadings of the carbon black compound of from 0.1 to 2.0 percent by weight based on the combined total weight of the amorphous polyamide 25 . and carbon black compound. The melt index data are summarized in Table 1. A melt index measurement was attempted for a loading of 5 weight percen~ carbon black oompound but the mix~ure was too VisGous to stir blend well. The melt index of resin containing no carbon black is set forth in compara~ive Example A.

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2 ~ 3 9 ~ 3 6 OBCT0~973 g Melt Index Data for Carbon Black Compound Loadings in an Amorphous Polyanide aLoading Level bMelt Index*
(w~iqht p~ent) (~ram Der lQ minla~es) A. 0 0.190 0.1 1.518 2 0.2 1.885 3 0.5 2.~85 4 1.~ 1.441 2.0 0.~60 .

* at 315C and 1200 gram load after a 6 minute preheat.

a Weight percent~of the carbon black eompound added ~o the amorphous polyamide based on the combined total weight of the amorphous polyamide and the carbon black compound.

b Conducted using a Tinius Olsen Extrusion Plastometer where measurement is amount of material extruded in ten minutes.

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08~T04973 DES~RIPTION OF EXAMPLES IN TABLE 2 An amorphous polyamide was derived from the reaction products of a diamine and a diester of a 5 d karboxylic acid. The diamine is a mixture of a 70 mole percent of toluenediamine and 30 mole percent of hexamethylenediamine based on the total moles of the diamine. The diester of the dicarboxylic acid is a mixture of a 75 mole percent of diphenylisophthalate and 25 mole percent of diphenylterephthalate based on the to~al moles of dicarboxylic acid.
In Examples 6 to 12 the amorphous polyamide was mixed with various types of carbon black compound.
ThP carbon black compound was added to maximize the melt flow while maintaining other properties of the mixture such as dynatup impact and tinting strength.
Table 2 gives the results of this study as well as properties of the differen~ carbon black compounds used. Fhe carbon black compound was present at a ZO level of 0.1 percent by weight based on ~he combined ~otal weigh~ of the carbon black compound and the amorphous polyamide. Most of the carbon black compounds studied showed an improvement over the control which was composed only of the amorphous polyamide melt flow. Oontrary to the other carbon black compounds tested, the carbon bl~ck compound of Table 2, Example 11, which had a particle diameter of 320 millimicrons, showed a melt flow which was essent~ally equivalent to the melt flow of the control which had no carbon black added to ~he amorphous polyamide.

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2 ~ ~ 9 ~ 3 6 tl~C~O~ 97 3 For examples 13 to 17 of Table 3 an amorphous polyamide was derived from the reaction products of a diamine and a diester of a dicarboxylic acid. The di ami ne was a mi xture of 50 mole percent 5 meta-xylenediamine and 50 mole pereent hexamethylenediamine based on the total moles of the diamine. The diester of the dicarbo%ylic acid was diphenylisophthala~e.
The amorphous polyamide was mixed with various types of carbon black compound. Table 3 ~ives the results of this study as well as properties of the different carbon black compounds used. The carbon black compound was present at a leYel of 0.1 percent by weight based on the combined total weight of the carbon black compound and the amorphous polyamide. In all cases the carbon black compounds studied showed an improvement over the control which was composed only - of the amorphous polyamide melt flow. Control B had no carbon black added to the amorphous polyamides.

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An amorphous polyamide was deriYed from the reaction products of a diamine and a dicarboxylic 5 acid. The diamine was hexamethylene diamine. The dicarboxylic acid was a mixture of 65 mole percent isophthalic acid and 35 mole percent terephthalic acid based on the total moles of the dicarboxylic acid.
This polyamide was commercially available as Selar PA
o ~DuPont). The polyamide was mixed with 0.1 percent of a furnace carbon black compound which had a particle diameter of 17 millimicrons~ density of 15 pounds per cubic foot, surface area of 210 square meters per gram, an oil absorption rate of 75 cubic centimeters per lO0 grams, and was available from Ca~ot Corporation under the commercial name Monarch 800.
The melt index at 265C and 1200 gram load after a 6 minute preheat was 67.5 grams/10 minutes ~or the carbon blaek containing amorphous polyamide and 3.38 grams/10 minutes for the neat polyamide.

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EX~MPL~ 19 An amorphous polyamide was derived from the reaction products of a diamine and a dicarboxyli~
acid. The diamine was a mixture of bis(4-amino-3-methylcyclohexyl)methane and Nylon 12. The di carboxyl i c aci d was i sophthal i c aci d . Thi s pol yami de was commercially a~ailable as Grilamid TR55 ~Emser Werke). The polyamide was mixed with 0.1 percent of a lQ furnace carbon black compound which had a particle diameter of 17 millimicrons, density of 15 pounds per cubic foot, surface area of 210 square meters per gram, an oil absorption rate of 75 cubic centimeters per 100 grams, and was available from Cabot Corporation under the commercial name Monarch 800.
The melt index at 265C and 1200 gram load after a 6 minute preheat was 3.35 gramsllO minutes for the carbon black containing amorphous polyamide and 1.15 gramsllO minutes for the neat palyamide.

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Claims

1. An amorphous polyamide composition comprising:
(a) an amorphous polyamide; and (b) a carbon black compound, said carbon black compound being present in said composition at a level of from 0.05 percent to 2.0 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound, said carbon black compound having a particle diameter less than 320 millimicrons.

2. The composition of Claim 1 wherein said amorphous polyamide comprises the reaction products of:
(a) a diamine; and (b) a dicarboxylic acid, said diamine being toluenediamine, said dicarboxylic acid being selected from the group consisting of:
(i) isophthalic acid, a mixture of isophthalic acid and terephthalic acid, and a mixture of isophthalic acid and aliphatic dicarboxylic acid.

3. The composition of Claim 1 wherein said amorphous polyamide is at a level of from 98.0 percent to 99.95 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

4. A fiber-reinforced thermoplastic article comprising:
(a) a long glass fiber mat;
(b) an amorphous polyamide; and (c) a carbon black compound, said carbon black compound being present in said composition at a level of from 0.05 percent to 2.0 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

5. The composition of Claim 4 wherein said long glass fiber mat is at a level of from 20 to 60 percent by weight based on the combined total weight of said long glass fiber mat, said amorphous polyamide and said carbon black compound.

6. An amorphous polyamide composition consisting essentially of:
(a) an amorphous polyamide; and (b) a carbon black compound, said carbon black compound being present in said composition at a level of from 0.05 percent to 2.0 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

7. A fiber-reinforced article consisting essentially of:
(a) a long glass fiber mat;
(b) an amorphous polyamide; and (c) a carbon black compound, said carbon black compound being present in said composition at a level from 0.05 percent to 2.0 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

8. The composition of Claim 1 wherein said carbon black compound is at a level of from 0.2 percent to 1.0 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

9. The composition of Claim 4 wherein said carbon black compound is at a level of from 0.2 percent to 1.0 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

10. The composition of Claim 1 wherein said carbon black compound is at a level of about 0.5 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

11. The composition of Claim 4 wherein said carbon black compound is at a level of about 0.5 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

12. A fiber-reinforced composition comprising;
(a) reinforcing fibers;
(b) an amorphous polyamide; and (c) a carbon black compound, said carbon black compound being present in said composition at a level of from 0.05 percent to 2.0 percent by weight based on the combined total weight of said amorphous polyamide and said carbon black compound.

13. The composition of Claim 12 wherein said reinforcing fibers are selected from the group consisting of:
(i) long glass fiber mat, carbon fiber, glass fibers, mineral fibers and metal fibers.

14. The composition of Claim 1 wherein said amorphous polyamide comprises the reaction products of:
(a) a diamine; and (b) a dicarboxylic acid, said diamine being hexamethylenediamine, said dicarboxylic acid being selected from the group consisting of:
(i) isophthalic acid, a mixture of isophthalic acid and terephthalic acid, and a mixture of isophthalic acid and aliphatic dicarboxylic acid.

15. The composition of Claim 1 wherein said amorphous polyamide comprises the reaction products of:
(a) a diamine; and (b) a dicarboxylic acid, said diamine being meta-xylenediamine, said dicarboxylic acid being selected from the group consisting of:
(i) isophthalic acid, a mixture of isophthalic acid and terephthalic acid, and a mixture of isophthalic acid and aliphatic dicarboxylic acid.

16. The composition of Claim 1 wherein said amorphous polyamide comprises the reaction products of:
(a) a diamine; and (b) a dicarboxylic acid, said diamine being bis(para-aminocyclohexylamethane, said dicarboxylic acid being selected from the group consisting of:
(i) isophthalic acid, a mixture of isophthalic acid and terephthalic acid, and a mixture of isophthalic acid and aliphatic dicarboxylic acid.

17. The composition of Claim 1 wherein said amorphous polyamide comprises the reaction products of:
(a) a diamine; and (b) a dicarboxylic acid, said diamine being 2,2,3-trimethyl-hexamethylenediamine, said dicarboxylic acid being selected from the group consisting of:
(i) terephthalic acid, a mixture of isophthalic acid and terephthalic acid, and a mixture of terephthalic acid and aliphatic dicarboxylic acid.

18. The composition of Claim 1 wherein said amorphous polyamide comprises the reaction products of:
(a) a diamine; and (b) a dicarboxylic acid, said diamine being a mixture of bis(4-amino-3-methylcyclohexyl) methane and lauryl lactam, said dicarboxylic acid being selected from the group consisting of:
(i) isophthalic acid, a mixture of isophthalic acid and terephthalic acid, and a mixture of isophthalic acid and aliphatic dicarboxylic acid.

19. The invention as defined in any of the preceding claims including any further features of novelty disclosed.