RECYCLED POLYETHYLENE TEREPHTHALATE COMPOSITION

Abstract

A composition for production of injection-molded articles is made of recycled polyethylene terephthalate in an amount of over 90 wt %, a nucleation agent selected from salts of citrate acid, salts of carbonic acid, titanium oxide and mixtures thereof in an amount of 0.2-1 phr, and an impact modifier in the form of an unsaturated organic compound selected from acids, anhydrides, esters and metallic salts of at least one of the following: maleic, acrylic, methacrylic, itaconic, crotonic, alpha-methyl crotonic and cinnamic, in an amount of 2-4 phr. Optical brighteners, heat stabilizers and wax can also be added. The composition has high tensile strength, low shrinkage and high color stability, especially when compared to pure RPET.

Claims

1. A composition configured for production of injection-molded articles, comprising: (a) recycled polyethylene terephthalate in an amount of over 90 wt %; (b) a nucleation agent selected from the group consisting of salts of citrate acid, salts of carbonic acid, titanium oxide and mixtures thereof in an amount of 0.2-1 phr, and (c) an impact modifier in the form of an unsaturated organic compound selected from the group consisting of acids, anhydrides, esters and metallic salts of at least one of the following: maleic, acrylic, methacrylic, itaconic, crotonic, alpha-methyl crotonic and cinnamic, in an amount of 2-4 phr.

2. The composition according to claim 1, further comprising virgin polyethylene terephthalate in an amount of up to 7 phr.

3. The composition according to claim 1, further comprising an optical brightener in the form of a compound having at least four conjugated double bonds in an amount of up to 1 phr.

4. The composition according to claim 1, further comprising a heat stabilizer in the form of a primary antioxidant in the form of a hindered phenol or secondary aromatic amine, or a secondary antioxidant containing phosphorous in an amount of up to 0.5 phr.

5. The composition according to claim 1, further comprising a polyolefin-based wax in an amount of up to 1.5 phr.

6. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 96.9 wt %, Trisodium Citrate in an amount of 0.2 phr, PE-g-MAH in an amount of 2.0 phr, and 2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole in an amount of 1.0 phr.

7. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 96.5 wt %, Trisodium Citrate in an amount of 0.6 phr, EMA-GMA in an amount of 2.0 phr, and 2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole in an amount of 1.0 phr.

8. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 91.7 wt %, Virgin PET in an amount of 5 phr Trisodium Citrate in an amount of 1.0 phr, PP-g-MAH in an amount of 2.0 phr, and 2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole in an amount of 1.0 phr.

9. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 90.1 wt %, Virgin PET in an amount of 5 phr Trisodium Citrate in an amount of 1.0 phr, PP-g-MAH in an amount of 4.0 phr, and 2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole in an amount of 1.0 phr.

10. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 90.1 wt %, Virgin PET in an amount of 7 phr, Trisodium Citrate in an amount of 1.0 phr, PP-g-MAH in an amount of 2.0 phr, and 2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole in an amount of 1.0 phr.

11. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 90.3 wt %, Virgin PET in an amount of 7 phr TiO.sub.2 in an amount of 0.3 phr, Trisodium Citrate in an amount of 1.0 phr, PP-g-MAH in an amount of 2.0 phr.

12. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 90.2 wt %, Virgin PET in an amount of 7 phr, Trisodium Citrate in an amount of 1.0 phr, PP-g-MAH in an amount of 2.0 phr, Pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate) in an amount of 0.2 phr, tris(2,4-ditert-butylphenyl)phosphite in an amount of 0.2 phr and Polyethylene wax in an amount of 0.5 phr.

13. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 90.3 wt %, Virgin PET in an amount of 7 phr, TiO.sub.2 in an amount of 0.3 phr, CaCO.sub.3 in an amount of 1.0 phr, PP-g-MAH in an amount of 2.0 phr, Pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate) in an amount of 0.2 phr, and tris(2,4-ditert-butylphenyl)phosphite in an amount of 0.2 phr.

14. The composition according to claim 1, wherein the composition consists of the following components: RPET in an amount of 95.1 wt %, TiO.sub.2 in an amount of 0.3 phr, Trisodium Citrate in an amount of 1.0 phr, PP-g-MAH in an amount of 2.0 phr, Pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate) in an amount of 0.2 phr, tris(2,4-ditert-butylphenyl)phosphite in an amount of 0.2 phr and Polyethylene wax in an amount of 1.5 phr.

15. A molded product consisting of the composition according to claim 1.

16. A method for producing a molded product, comprising placing a composition in an injection molding machine and molding the product, wherein the composition comprises: (a) recycled polyethylene terephthalate in an amount of over 90 wt %; (b) a nucleation agent selected from the group consisting of salts of citrate acid, salts of carbonic acid, titanium oxide and mixtures thereof in an amount of 0.2-1 phr; and (c) an impact modifier in the form of an unsaturated organic compound selected from the group consisting of acids, anhydrides, esters and metallic salts of at least one of the following: maleic, acrylic, methacrylic, itaconic, crotonic, alpha-methyl crotonic and cinnamic, in an amount of 2-4 phr.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will describe specific examples of RPET compositions according to the invention. The Examples are for illustration of various compositions within the scope of the invention and are not intended as a limitation of the claims. The compositions described in the examples are made by mixing the listed components, melting, pelletizing by extrusion and then placing them in an injection molding machine to mold various products that are then tested for strength, shrinkage and color.

[0018] In the examples, the following abbreviations are defined as follows:

[0019] RPET=Recycled Polyethylene Terephthalate

[0020] PET=Virgin Polyethylene Terephthalate

[0021] TiO.sub.2=Titanium Oxide

[0022] NA=Nucleation Agent

[0023] IM=Impact modifier

[0024] OB=Optical brightener

[0025] Pri-HS=Primary Heat Stabilizer

[0026] Sec-HS=Secondary Heat Stabilizer

[0027] The amounts in each example are given as a percent by weight of RPET of the entire composition, and as PHR (parts per hundred resin) of the other components. The other components are defined as parts per hundred parts of RPET.

EXAMPLE 1

[0028] RPET: 96.9 wt %

[0029] NA(trisodium citrate) 0.2 phr

[0030] IM(PE-g-MAH): 2.0 phr

[0031] OB: 1.0 phr

[0032] (2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole)

EXAMPLE 2

[0033] RPET: 96.5 wt %

[0034] NA (trisodium citrate): 0.6 phr

[0035] IM (EMA-GMA): 2.0 phr

[0036] OB: 1.0 phr

[0037] (2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole)

EXAMPLE 3

[0038] RPET: 91.7 wt %

[0039] PET: 5.0 phr

[0040] NA (trisodium citrate): 1.0 phr

[0041] IM (PP-g-MAH): 2.0 phr

[0042] OB: 1.0 phr

[0043] (2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole)

EXAMPLE 4

[0044] RPET: 90.1 wt %

[0045] PET: 5.0 phr

[0046] NA(trisodium citrate): 1.0 phr

[0047] IM (PP-g-MAH): 4.0 phr

[0048] OB: 1.0 phr

[0049] (2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole)

EXAMPLE 5

[0050] RPET: 90.1 wt %

[0051] PET: 7.0 phr

[0052] NA (trisodium citrate): 1.0 phr

[0053] IM (PP-g-MAH): 2.0 phr

[0054] OB: 1.0 phr

[0055] (2,2′-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole)

EXAMPLE 6

[0056] RPET: 90.3 wt %

[0057] PET: 7.0 phr

[0058] TiO.sub.2: 0.3 phr

[0059] NA (trisodium citrate): 1.0 phr

[0060] IM (PP-g-MAH): 2.0 phr

EXAMPLE 7

[0061] RPET: 90.2 wt %

[0062] PET: 7.0 phr

[0063] NA (trisodium citrate): 1.0 phr

[0064] IM (PP-g-MAH): 2.0 phr

[0065] Pri-HS: 0.2 phr

[0066] (Pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate)

[0067] Sec-HS: 0.2 phr

[0068] (tris(2,4-ditert-butylphenyl)phosphite)

[0069] Wax (PE): 0.5 phr

EXAMPLE 8

[0070] RPET: 90.3 wt %

[0071] PET: 7.0 phr

[0072] TiO.sub.2: 0.3 phr

[0073] NA (CaCO.sub.3) 1.0 phr

[0074] IM (PP-g-MAH): 2.0 phr

[0075] Pri-HS: 0.2 phr

[0076] (Pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate)

[0077] Sec-HS: 0.2 phr

[0078] (tris(2,4-ditert-butylphenyl)phosphite)

EXAMPLE 9

[0079] RPET: 95.1 wt %

[0080] TiO.sub.2: 0.3 phr

[0081] NA (trisodium citrate) 1.0 phr

[0082] IM (PP-g-MAH): 2.0 phr

[0083] Pri-HS: 0.2 phr

[0084] (Pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate)

[0085] Sec-HS: 0.2 phr

[0086] (tris(2,4-ditert-butylphenyl)phosphite)

[0087] Wax (PE-wax) 1.5 phr

[0088] The compositions are set forth in the table 1 below:

TABLE-US-00001 RPET PET TiO.sub.2 NA NA IM IM IM Detailed components Recycled Polyethylene Homopolymer Trisodium PP-g- PE-g- EMA- Terephthalate (IV = 1.2) TiO.sub.2 Citrate CaCO.sub.3 MAH MAH GMA Unit % phr phr phr phr phr phr phr phr Reference 100 100 Example 1 96.9 100 0 0 0.2 0 0 2 0 Example 2 96.5 100 0 0 0.6 0 0 0 2 Example 3 91.7 100 5 0 1 0 2 0 0 Example 4 90.1 100 5 0 1 0 4 0 0 Example 5 90.1 100 7 0 1 0 2 0 0 Example 6 90.3 100 7 0.3 1 0 2 0 0 Example 7 90.2 100 7 0 1 0 2 0 0 Example 8 90.3 100 7 0.3 0 1 2 0 0 Example 9 95.1% 100 0 0.3 1 0 2 0 0 OB Pri-HS Sec-HS Wax Detailed components 2,2′-(1,2- Pentaerythritol tetrakis[3- Ethenediyldi-4,1- [3,5-di-tert-butyl-4- tris(2,4-ditert- phenylene)bisbenzoxazole hydroxyphenyl]propionate butylphenyl)phosphite PE-wax Unit phr phr phr phr Reference Example 1 1 0 0 0 Example 2 1 0 0 0 Example 3 1 0 0 0 Example 4 1 0 0 0 Example 5 1 0 0 0 Example 6 0 0 0 0 Example 7 0 0.2 0.2 0.5 Example 8 0 0.2 0.2 0 Example 9 0 0.2 0.2 1.5

[0089] Each of the compositions was tested for tensile strength, shrinkage in the mold, and color. The results are listed in Table 2 below:

TABLE-US-00002 TABLE 2 Tensile Shrinkage Strength kg (sink mark) Color Reference 2.07 Serious inconsistently yellowish Example 1 4.8 No consistently bluish white Example 2 22.2 No consistently bluish white Example 3 7.1 No consistently bluish white Example 4 8.2 No consistently bluish white Example 5 28.7 No consistently bluish white Example 6 5.6 No consistently creamy white Example 7 6.54 No consistently creamy white Example 8 5.67 No consistently creamy white Example 9 11.28 No consistently creamy white

[0090] As can be seen from Table 2, the products produced according to the invention exhibit no serious shrinkage, evidenced by sink marks, little yellowing, and high tensile strength, especially when compared to a reference sample of pure RPET, which is yellowish, exhibits serious shrinkage and has a significantly lower tensile strength as compared to the compositions according to the invention.

[0091] The compositions according to the invention have many advantages, especially when compared to pure RPET or virgin PET.

[0092] The present invention has the advantage of being made with >90% Recycled content, and greater than 95% content of polyethylene terephthalate. The compositions are highly suitable for injection molding, yielding a cycle time within 20 seconds. The compositions of the present invention exhibit low shrinkage and improving sink marks when comparing to 100% recycled PET.

[0093] In addition, the compositions of the present invention make RPET processable by injection molding without requiring the addition of glass, minerals or inorganic fibers, yet is still able to be colored to commercial standards.

[0094] Furthermore, the compositions according to the invention have increased tensile strength of between 2 and 14 times that of 100% recycled PET as well as increased color stability when compared to 100% recycled PET. The composition according to the present invention avoids the use of any polymers that do not consist of hydrogen, oxygen, and carbon.