High isotactic PP resin with wide melting distribution having improved BOPP film properties and easy processing characteristics
View Patent ↗The present invention relates to a new biaxially oriented polypropylene (BOPP) film, a process for the preparation of such film as well as the use of a polypropylene for the preparation of such film and an article comprising such film.
1. Biaxially oriented polypropylene (BOPP) film comprising: a polypropylene (PP) having a residual crystallinity f RC of ≦0.4 at a temperature (T) being 1° C. below the melting temperature (T m ) of the polypropylene (PP) [T=T m −1].
2. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the polypropylene (PP) has a residual crystallinity f RC of ≦0.3 at the melting temperature (T m ) of the polypropylene (PP).
3. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the biaxially oriented polypropylene (BOPP) film comprises a polypropylene (PP) comprising:
(a) crystalline fractions crystallizing in the temperature range of
(i) 150 to 160° C., and
(ii) 160 to 170° C.,
wherein the amount of the two crystalline fractions [wt. % ] differs from each other of more than 10.0 wt. %, wherein further said fractions are determined by the stepwise isothermal segregation technique (SIST), and/or
(b) crystalline fractions crystallizing in the temperature range of
(i) 160 to 170 ° C., and
(ii) 170 to 180 ° C.,
wherein the amount of the two crystalline fractions [wt. % ] differs from each other of not more than 7.0 wt. %, wherein further said fractions are determined by the stepwise isothermal segregation technique (SIST), and/or
(c) crystalline fractions crystallizing above 160° C. of more than 63.0 wt. %, wherein said fractions are determined by the stepwise isothermal segregation technique (SIST).
4. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the biaxially oriented polypropylene (BOPP) film comprises a polypropylene (PP) comprising:
(a) crystalline fractions crystallizing in the temperature range of below 120° C. in an amount of not more than 1.0 wt. %, wherein said fractions are determined by the stepwise isothermal segregation technique (SIST), and/or
(b) crystalline fractions crystallizing in the temperature range of below 150° C. in an amount of not more than 16.0 wt. %, wherein said fractions are determined by the stepwise isothermal segregation technique (SIST), and/or
(c) crystalline fractions crystallizing above 180° C. in an amount of not more than 1.0 wt. %, wherein said fractions are determined by the stepwise isothermal segregation technique (SIST).
5. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the biaxially oriented polypropylene (BOPP) film comprises a polypropylene (PP) having:
(a) a melting temperature (T m ) measured by differential scanning calorimetry (DSC) of at least 160 ° C., and/or
(b) a crystallization temperature (T c ) measured by differential scanning calorimetry (DSC) of at least 115° C.
6. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the biaxially oriented polypropylene (BOPP) film comprises a polypropylene (PP) having:
(a) a melt flow rate MFR 2 (230° C.) measured according to ISO 1133 of≦7.0 g/10 min, and/or
(b) a xylene cold soluble fraction (XCS) determined at 23° C. according ISO 6427 of≧2.0 wt. %, and/or
(c) an mmmm pentad concentration of≧95.0% determined by NMR-spectroscopy, and/or
(d) 2,1-erythro reciodefects of below 1.0% determined by 13 C-NMR spectroscopy.
7. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the biaxially oriented polypropylene (BOPP) film comprises a polypropylene (PP) being a propylene homopolymer (H-PP).
8. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the biaxially oriented polypropylene (BOPP) film has been prepared at a yield force in machine direction of≦20 N.
9. Process for the preparation of a biaxially oriented polypropylene (BOPP) film, the process comprising at least the steps of:
(a) providing a polypropylene (PP) as defined in claim 1 , and
(b) stretching the polypropylene of step a) in machine direction and transverse direction.
10. Biaxially oriented polypropylene (BOPP) film according to claim 1 , wherein the polypropylene (PP) has:
(a) a crystallinity of>61.5 wt. %, and
(b) a shrinkage of<2.2%,
when drawn at a draw ratio in machine direction and transverse direction of 5.0 and as drawing temperature (Tdraw) being 1° C. below the melting temperature (T m ) of the polypropylene (PP) [T draw =T m −1].
11. Biaxially oriented polypropylene (BOPP) film comprising: a polypropylene (PP), said polypropylene (PP) has:
(a) a crystallinity of>61.5 wt. %, and
(b) a shrinkage of<2.2%,
when drawn at a draw ratio in machine direction and transverse direction of 5.0 and as drawing temperature (Tdraw) being 1° C. below the melting temperature (T m ) of the polypropylene (PP) [T draw =T m −1].