Polymer compositions and articles having improved reheat characteristics
View Patent ↗Polymer compositions, for example of polyethyleneterephthalate bottles or preforms, include a reheat additive which has reducing transmission/increasing absorbance across the IR region as the wavelength increases. The reheat additive may be a titanium nitride, made by a plasma vapor deposition technique. Advantageously, the material may be used at a lower level than hitherto known materials or may be used at the same levels as hitherto but provide a greater reheat effect. Example 3a shown in the figure illustrates the absorbance of a preferred material.
1. An article comprising a polymer composition which includes a reheat additive wherein said article includes at least one of the following properties:
(A) the ratio defined as the absorbance at 750 nm divided by the absorbance at 700 nm is greater than 1;
(B) the ratio defined as the absorbance at 800 nm divided by the absorbance at 700 nm is greater than 1;
(C) the ratio defined as the absorbance at 850 nm divided by the absorbance at 700 nm is greater than 1;
(D) the ratio defined as the absorbance at 900 nm divided by the absorbance at 700 nm is greater than 1;
(E) the ratio defined as the absorbance at 950 nm divided by the absorbance at 700 nm is greater than 1;
(F) the ratio defined as the absorbance at 1000 nm divided by the absorbance at 700 nm is greater than 1;
(G) the ratio defined as the absorbance at 1050 nm divided by the absorbance at 700 nm is greater than 1;
(H) the ratio defined as the absorbance at 1100 nm divided by the absorbance at 700 nm is greater than 1;
(I) the ratio defined as the transmission at 1000 nm divided by the transmission at 500 nm is less than 1.04;
(J) the % transmission at 1000 nm minus the % transmission at 500 nm is less than 2.75%.
2. An article according to claim 1 , wherein said article includes at least 3 of properties (E) to (H).
3. An article according to claim 1 , wherein said article includes at least 4 of properties (A) to (H).
4. An article according to claim 1 wherein said article includes property (H).
5. An article according to claim 1 , wherein the ratio for property (A) is lower than the ratio for property (B) which is lower than the ratio for property (C) which is lower than the ratio for property (B) which is lower than the ratio for property (E) which is lower than the ratio for property (F) which is lower than the ratio for property (G).
6. An article according to claim 1 , wherein said article includes each of properties (A) to (J).
7. An article according to claim 1 , wherein the ratio of the absorbance in the region 701 nm-1100 nm divided by the absorbance in the region 450-700 nm is at least 1.1.
8. An article according to claim 1 , wherein said article is a bottle or a preform for a bottle.
9. An article according to claim 1 , wherein said article has an L* measured on the CIELab scale of at least 65.
10. An article according to claim 1 , wherein said reheat additive includes titanium moieties and nitrogen moieties.
11. An article according to claim 1 , wherein said reheat additive includes particles having at least one dimension less than 10 microns.
12. An article according to claim 1 , wherein said polymer composition includes at least 0.01 ppm and less than 200 ppm of said reheat additive based on the weight of said polymer composition.
13. An article according to claim 1 , wherein said reheat additive is made by a physical vapour deposition technique.
14. An article according to claim 1 , wherein said reheat additive has a structure selected from porous columnar, dense columnar and fully dense.
15. A polymer composition for an article as described in claim 1 , the polymer composition, when moulded into a 3 mm thickness plaque, having at least one of properties (A) to (J).
16. An article according to claim 1 , wherein said article includes at least one of the following properties:
(AA) the ratio defined as the absorbance at 900 nm divided by the absorbance at 850 nm is greater than 1;
(BB) the ratio defined as the absorbance at 950 nm divided by the absorbance at 850 nm is greater than 1;
(CC) the ratio define as the absorbance at 1000 nm divided by the absorbance at 850 nm is greater than 1;
(DD) the ratio defined as the absorbance at 1050 nm divided by the absorbance at 850 nm is greater than 1;
(EE) the ratio defined as the absorbance at 1100 nm divided by the absorbance at 850 nm is greater than 1.
17. An article according to claim 1 , wherein said reheat additive includes titanium moieties and nitrogen moieties, wherein the ratio of the number of atoms of titanium to the number of atoms of nitrogen in the additive is greater than 1 and is less than 1.9.