Concentrate Composition For Polymeric Chain Extension

Abstract

The present invention relates to a concentrate composition comprising at least one terephthalic acid ester of formula (1)

##STR00001##

wherein
R.sup.1 and R.sup.2 are the same or different and denote a C.sub.1-C.sub.10-alykl; and at least one carrier resin.

Claims

1. A concentrate composition comprising at least one terephthalic acid ester of formula (1) ##STR00004## wherein R.sup.1 and R.sup.2 are the same or different and area C.sub.1-C.sub.10-alkyl; and at least one carrier resin.

2. The composition as claimed in claim 1, wherein R.sup.1 and R.sup.2 are the same or different and area C.sub.1-C.sub.2-alkyl.

3. The composition as claimed in claim 1, wherein R.sup.1 and R.sup.2 are methyl.

4. The composition as claimed in claim 1, wherein the carrier resin is selected from the group consisting of polyethylene, polyethylene-norbonene copolymers, polypropylene, polybutylene, polymethyl pentene, polyethylene-vinyl acetate copolymers, polycarbonate, polystyrene, polystyrene block copolymers, polybutadien, polyisopren, polyethylene-butylen, polyacrylates, polyvinyl chloride, chlorinated polyethylene, polyvinylidene chloride, polyethylene-acrylate copolymers, acrylnitril-butadiene-styrene-copolymers, and mixtures thereof.

5. The composition as claimed in claim 1, wherein the carrier resin is acrylnitril-butadiene-styrene-copolymer, polystyrene or polycarbonate.

6. The composition as claimed in claim 1, wherein the carrier resin is polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate glycol, maleic anhydride grafted polyethylene, or a mixture thereof.

7. The composition as claimed in claim 1, wherein the compound of formula (1) is present in an amount of between 0.01 to 99.9 wt.-%, relative to the total weight of the concentrate composition.

8. The composition as claimed in claim 1, wherein the compound of formula (1) is present in an amount of between 5.0 and 50.0 wt.-%, relative to the total weight of the concentrate composition.

9. A method for preparing a composition as claimed in claim 1, comprising the step of combining, by dispersive or distributive mixing, the compound of formula (1) and the carrier resin.

10. A chain extender for step-growth polycondensates comprising a composition as claimed in claim 1.

11. The chain extender as claimed in claim 10, wherein the polycondensates are polyamides, polyesters, polycarbonates, polyurethanes, polystyrene co-maleic anhydride or polyethylene co-acrylic acid.

12. The chain extender as claimed in claim 10, wherein the compound of formula (1) is present in an amount of from 0.1 to 50 wt.-%, relative to the total weight of the concentrate composition and the polycondensate.

13. The chain extender as claimed in claim 10, wherein the polycondensates are manufactured into polymeric articles.

14. The use chain extender as claimed in claim 13, wherein the polymeric articles are sheets, films, containers or fibers.

Description

SUMMARY OF THE INVENTION

[0012] Accordingly the present invention is directed to a concentrate composition useful in modifying the molecular weight of a step-growth polymer which concentrate comprises an alkyloxy-functionalized terephthalic acid and at least one carrier resin.

[0013] According to a preferred embodiment, a concentrate composition includes at least one alkyloxy-functionalized terephthalic acid and at least one reactive carrier resin.

[0014] According to another preferred embodiment, a concentrate composition includes at least one alkyloxy-functionalized terephthalic acid and at least one non-reactive carrier resin.

[0015] As the chain extender is physically homogeneously dispersed in the carrier, while the concentrate composition is mixed with the polymer, the potential for localized higher concentrations of chain extender is minimized. Furthermore, when introduced into a molding apparatus, the concentrate composition of the present invention prevents premature reaction of alkyloxy-functionalized terephthalic acid chain extender within the let down polymer by increasing the time required to melt the concentrate, this delayed reaction time permits the chain extender to be fully dispersed throughout the polymer, resulting in homogeneous chain extension.

[0016] Depending on the carrier resin the concentrate composition of the invention can be solid or liquid, a solid concentrate composition being preferred.

[0017] The present invention is directed to a concentrate composition comprising at least one terephthalic acid ester of formula (1)

##STR00002##

wherein [0018] R.sup.1 and R.sup.2 are the same or different and denote C.sub.1-C.sub.10-alkyl, preferably C.sub.1-C.sub.6-alkyl, more preferably C1-C4-alkyl, most preferably C1-C2-alkyl;
and at least one carrier resin.

[0019] Examples for compounds of formula (1) are dimethylterephthalat, diethylterephthalat, dipropylterephthalat, dibutylterephthalat, dipentylterephthalat, dihexylterephthalat, diheptylterephthalat, dioctylterephthalat, dinonylterephthalat or didecylterephthalat.

[0020] The preferred chain extender is dimethylterephthalat (DMT) of formula (2)

##STR00003##

[0021] This molecule is manufactured by oxidation of the methyl groups on p-xylene and afterwards oxidation to a carboxylic acid, reaction with methanol gives the methyl ester, dimethyl terephthalate. Another possibility is the oxidation of para-xylene or mixed xylene isomers, followed by esterification. Also a customary process to manufacture dimethyl terephthalate is by esterification of purified terephthalic acid with methanol generated by the catalytic homogeneous oxidation of para-xylene. The most widely used technology is based on paraxylene using oxidation and esterification steps. Para xylene is oxidized in the liquid phase by air in the presence of a cobalt salt catalyst to form an oxidate containing p-toluic acid and monomethyl terephthalate. Esterification is carried out in the presence of methanol to form dimethyl terephthalate.

[0022] The at least one carrier resin is either a non reactive resin, a reactive resin or a mixture thereof. Preferably, a non-reactive carrier resin is utilized in the concentrate composition of the present invention as the non reactive carrier resin provides an inert carrier, thereby preventing the chain extender from reacting until the concentrate composition is dispersed within the let down polymer. The chain extender does not react with the non-reactive carrier resin to cause any appreciable chain extension within the non-reactive carrier resin.

[0023] The non reactive carrier resin can be polyethylene, polyethylene-norbornene copolymers, polypropylene, polybutylene, polymethyl pentene, polyethylene-vinyl acetate copolymers, polycarbonate (PC), polystyrene (PS), polystyrene block copolymers, polybutadiene, polyisoprene, polyethylene-butylene, polyacrylates, polyvinyl chloride, chlorinated polyethylene, polyvinylidene chloride, polyethylene-acrylate copolymers, acrylnitril-butadiene-styrene-copolymers (ABS), and mixtures thereof. The preferred non-reactive carrier resin is ABS, PS, and polycarbonate.

[0024] The reactive carrier resin can be polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate glycol, maleic anhydride grafted polyethylene (MAH-g PE) and a mixture thereof.

[0025] The exact ratio of chain extender to carrier resin in the concentrate composition is application specific, depending upon the activity of the carrier resin and the desired degree of chain extension in final polymeric product. The terephthalic acid ester may be present in the concentrate composition in amounts between approximately 0.01 to 99.9 wt.-%, preferably between approximately 5.0 and 50.5 wt.-%; and most preferably between 10.0 and 25.0 wt.-%, relative to the total weight of the concentrate composition.

[0026] Other materials which are substantially chemically inert may be added to the concentrate composition depending upon the desired properties of the polymer.

[0027] Representative examples of such materials include anti-static agents, foaming agents, flame retardants, color concentrates, anti-oxidants, UV stabilizers, anti-block agents, anti-fog agents, anti-slip agents, anti-microbial agents and slip additives.

[0028] These other materials can be present in the concentrate composition of the invention in amounts of from 0.001 to 99%, preferably of from 0.001 to 50% by weight, relative to the total weight of concentrate composition.

[0029] If present, the lower limit of said other materials is expediently 0.01% by weight.

[0030] The method by which the concentrate composition is made is not particularly limited and can be accomplished by any known method for dispersive or distributive mixing, preferably by extrusion, e.g. in a twin-screw extruder.

[0031] Further, the concentrate composition of the present invention can be formed in a variety of geometrical shapes, including, but not limited to pellets, spheres, flakes, agglomerates, prills and the like.

[0032] The concentrate composition may be used to impart chain extension properties on any let down polymer with at least one carboxyl reactive group. Representative examples of such polymers include step-growth polycondensates such as polyamides, polyesters and polycarbonates. The polymer can also be an addition polymer such as polyurethanes, polystyrene co-maleic anhydride or polyethylene co-acrylic acid.

[0033] For said use the concentrate composition is expediently melt compounded with the let down polymer in any thermoplastic forming apparatus normally employed in the industry and is melted at a temperature appropriate for melting or softening the let down polymer, in accordance with normal molding techniques. The exact concentration of the concentrate composition is dependent upon the desired end characteristic of the let down polymer and is therefore application specific. The amount of the concentrate composition to be added to the let-down polymer may range from 0.1 to 50.0 wt.-%, preferably 1.0 to 30.0 wt.-%, more preferably 5.0 to 25.0 wt.-%, relative to the total weight of the concentrate composition and the let-down polymer. The residence time which the concentrate composition in combination with the let down polymer stays on the extruder can vary between 1 s up to 10000 s, preferably 1 s up to 1000 s, more preferably 10 s up to 600 s, even more preferably 15 s to 100 s, most preferably 20 s to 50 s.

[0034] The concentration of the chain extender in the let-down polymer is preferably from 0.01 to 10 wt. %, more preferably from 0.1 to 1 wt. %, even more preferably 0.2 to 0.5 wt %, relative to the total weight of the concentrate composition and the let-down polymer.

[0035] The concentrate composition of the present invention may be used in the manufacture of various polymeric articles, non limiting examples of which includes, polymeric sheets, films, containers, e.g. bottles, fibers or multidimensional articles comprising polycondensates.

[0036] The following examples will serve to more fully illustrate the invention. Percentages are weight percent, unless indicated otherwise. The measurement of the intrinsic viscosity (I.V.) was used to measure the molecular weight of the chain extended polymer as the intrinsic viscosity is a unique function of the molecular weight of a polymer. The I.V. was detected by using a Davenport viscosimeter for melt viscosity measurements, e.g. for PET, in the molten state extruded through a calibrated die using high pressure nitrogen gas.

EXAMPLES

Example 1

[0037] Five formulations A-E were extruded in accordance with normal industry procedure using a Leistritz MASS technology (27 mm/40D). Therefor a masterbatch containing 10% of the chain extender in polycarbonate as carrier system was extruded. This masterbatch was incorporated in PET (amounts indicated in Table 1) by extrusion at temperatures between 200 and 300° C. with an average residence time of 35 to 40 s. The intrinsic viscosity (I.V.) was determined relative to neat PET.

TABLE-US-00001 TABLE 1 Concentration Concentration of DMT Increase of I.V. of PET chain extender in final relative to neat PET Sample [%] product [%] [%] A 100 0 0 B 99.9 0.1 20 C 99.85 0.15 27 D 99.8 0.2 25 E 99.775 0.225 25

[0038] The used PET was RAMAPET® R 180 GR BB (Indorama Plastics, 192 000 g/mol).

Example 2

[0039] Nine formulations A-I were extruded in accordance with normal industry procedure using a Leistritz MASS technology (27 mm/40D). Therefore a masterbatch containing 10% of the chain extender in polycarbonate as carrier system was prepared. This masterbatch was incorporated in PET (amounts indicated in Table 2) by extrusion at temperatures between 200 and 300° C. In this trial the residence times of material within the extruder was varied.

TABLE-US-00002 TABLE 2 Concentration of Increase of Concentration of chain extender in Residence I.V. relative PET finished product time to neat PET Sample [%] [wt.-%] [s] [%] A 100 0 35 0 B 100 0 50 0 C 100 0 64 0 D 99.9 0.1 35 13 E 99.9 0.1 50 14 F 99.9 0.1 64 10 G 99.7 0.3 35 25 H 99.7 0.3 50 17 I 99.7 0.3 64 17

[0040] The used PET was RAMAPET® R 180 GR BB and the chain extender was DMT.

[0041] It is demonstrated that the chain extender works best at shorter residence time with high concentrations in process.

Example 3

[0042] Thirteen formulations A-M were extruded in accordance with normal industry procedure using a Leistritz MASS technology (27 mm/40D). Therefor a masterbatch containing 10% of the chain extender on different carrier systems was prepared. This masterbatch was incorporated in PET by extrusion at temperatures between 200 and 300° C.

TABLE-US-00003 TABLE 3 Concentration of Increase of Concentration chain extender in I.V. relative of PET finished product to neat PET Sample [%] [%] Carrier resin [%] A 100 0 — 0 B 99.9 0.1 PC 20 C 99.8 0.2 PC 27 D 99.9 0.1 PET 19 E 99.8 0.2 PET 21 F 99.9 0.1 PP 13 G 99.8 0.2 PP 17 H 99.9 0.1 MAH-g PE 22 I 99.8 0.2 MAH-g PE 24 J 99.9 0.1 PS 24 K 99.8 0.2 PS 31 L 99.9 0.1 ABS 30 M 99.8 0.2 ABS 31

[0043] The used PET was RAMAPET® R 180 GR BB and the chain extender was DMT.