AQUEOUS POLYOLEFIN DISPERSION

Abstract

The invention relates to an aqueous polyolefin dispersion comprising a. from 50 to 100 wt. % of an aqueous dispersion A comprising the following ingredients: i. from 60.0 to 98.9 wt. % of A1, a copolymer of polyethylene and (meth)acrylic acid [E(M)AA] or a mixture of different copolymers of polyethylene and (meth)acrylic acid, ii. from 1.0 to 39.0 wt. % of A2, another polymer or a mixture of other polymers, not being a copolymer of polyethylene and (meth)acrylic acid, selected from the group consisting of copolymers of ethylene and vinyl acetate (EVA) and copolymers of ethylene and vinyl acetate (EVA) modified with maleic anhydride, iii. from 0.1-10.0 wt. % of a silicate component A3 (wt. % refers to the relevant SiO2 content) and iv. from 0-20 wt. % of additive not being A1, A2 or A3,b. from 0 to 50 wt. % of a compound B, where compound B is a material dispersable or soluble in water and different from any of the ingredients of dispersion A whereinthe wt. % of A and B is based on the solid content of the whole aqueous polyolefin dispersion, the wt % of the ingredients of dispersion A is based on the solid content of dispersion A, the sum of the wt. % of ingredients i to iv) of dispersion A is 100%.

Claims

1. Aqueous polyolefin dispersion comprising: a. from 50 to 100 wt. % of an aqueous dispersion A comprising the following ingredients: i. from 60.0 to 98.9 wt. % of A1, A1 being a copolymer of ethylene and (meth)acrylic acid [E(M)AA] or a mixture of different copolymers of ethylene and (meth)acrylic acid, ii. from 1.0 to 39.0 wt. % of A2, A2 being another polymer or a mixture of other polymers, not being a copolymer of ethylene and (meth)acrylic acid, selected from the group consisting of copolymers one or more of a copolymer of ethylene and vinyl acetate (EVA) and a copolymer copolymers of ethylene and vinyl acetate (EVA) modified with maleic anhydride, A2 not being a copolymer of ethylene and (meth)acrylic acid, iii. from 0.1-10.0 wt. % of a silicate component A3 (wt. % refers to the relevant SiO.sub.2 content) and iv. from 0-20 wt. % of additive not being A1, A2 or A3, b. from 0 to 50 wt. % of a compound B, where compound B is a material dispersable or soluble in water and different from any of the ingredients of dispersion A, wherein the wt. % of A and B is based on the solid content of the whole aqueous polyolefin dispersion, the wt % of the ingredients of dispersion A is based on the solid content of dispersion A, the sum of the wt. % of ingredients i) to iv) of dispersion A is 100%.

2. The aqueous polyolefin dispersion according to claim 1, wherein the dispersion A comprises the following ingredients: i) from 80.5 to 98.5 wt. % of A1, ii) from 1.0 to 19.0 wt. % of A2, iii) from 0.3-5.0 wt. % of A3 and iv) from 0-10 wt. % of the additive not being A1, A2 or A3.

3. The aqueous polyolefin dispersion according to claim 1, wherein at least 60 wt. % of A1 has a content of (meth)acrylic based groups in the copolymer of 11-30 wt. %, wherein the wt. % is based on the total weight of the copolymer.

4. The aqueous polyolefin dispersion according to claim 1, wherein at least 60 wt. % of A2 has a content of vinyl acetate groups in the copolymer of 10-60 wt. %, wherein the wt. % is based on the total weight of the copolymer.

5. The aqueous polyolefin dispersion according to claim 1, wherein at least 60 wt. % of A3 is a synthetically produced crystalline silicate.

6. The aqueous polyolefin dispersion according to claim 1, wherein at least 60 wt. % of A3 is silica.

7. The aqueous polyolefin dispersion according to claim 1, wherein at least 60 wt. % of A3 is crystalline silica.

8. The aqueous polyolefin dispersion according to claim 1 comprising dispersed hybrid particles containing A1, A2 and A3.

9. The aqueous polyolefin dispersion according to claim 1 having a pH-value of 7.5-9.4.

10. A process for the preparation of an aqueous polyolefin dispersion, the aqueous polyolefin dispersion comprising: a. from 50 to 100 wt. % of an aqueous dispersion A comprising the following ingredients: i. from 60.0 to 98.9 wt. % of A1, A1 being a copolymer of ethylene and (meth)acrylic acid [E(M)AA] or a mixture of different copolymers of ethylene and (meth)acrylic acid, ii. from 1.0 to 39.0 wt. % of A2, A2 being one or more of a copolymer of ethylene and vinyl acetate (EVA) and a copolymer of ethylene and vinyl acetate (EVA) modified with maleic anhydride, A2 not being a copolymer of ethylene and (meth)acrylic acid, iii. from 0.1-10.0 wt. % of a silicate component A3 (wt. % refers to the relevant SiO.sub.2 content) and iv. from 0-20 wt. % of additive not being A1, A2 or A3, b. from 0 to 50 wt. % of a compound B, where compound B is a material dispersable or soluble in water and different from any of the ingredients of dispersion A wherein the wt. % of A and B is based on the solid content of the whole aqueous polyolefin dispersion, the wt % of the ingredients of dispersion A is based on the solid content of dispersion A, the sum of the wt. % of ingredients i) to iv) of dispersion A is 100%, the process comprising: intimately mixing all polymer components of the dispersion A at a temperature in the range of 50 C. to 200 C. after which a homogenous compound of all components is obtained and mixing the homogeneous compound with water, the compound B if contained, and a neutralizing agent at a temperature which is 2 to 20 C. above the highest melting temperature of the polymer components mixed to obtain the homogenous compound until an aqueous dispersion is obtained wherein all dispersed particles have a particle size below 150 m.

11. (canceled)

12. A heat-sealable structure comprising an aluminum substrate and a heat-seal lacquer comprising the aqueous polyolefin dispersion according to claim 1.

Description

EXAMPLES

[0076] Various aqueous dispersions were prepared using the following procedure: [0077] In a first step a compound was prepared by mixing and kneading the individual ingredients in a Leistritz ZSE 18 Maxx twin screw extruder at a temperature in the range of 80-150 C. (temperature was selected based on the ingredients), where different temperature zones were created inside the extruder. The pressure inside the extruder was 35 bar maximum. [0078] In a next step the extruded compound was fed into a Buchi 21 Pressure reactor, equipped with a dissolver mixer operating at speeds between 100-1000 rpm. The dispersion was prepared at elevated temperature in the range of 90-150 C. at sometimes elevated pressure (additional pressure in the range of 0-100 bar). After the formation of a homogenous dispersion, the dispersion was cooled. The cooling was done until the temperature of the dispersion was around 40 C.

[0079] The ingredients (in parts by weight, based on solid content) and conditions for each example are given in Table 1 below.

TABLE-US-00001 TABLE 1 Example 1* 2 3 4 5 6 7 8* Extruder EAA#3 95 95 95 90 90 90 60 90 EVA#4 5 5 5 10 10 10 40 10 silica 2 4 2 4 Laponite 4 4 Pressure Solid content (%) 25 25.5 26 25.5 26 26 26 25 vessel Base NH.sub.3 NH.sub.3 NH.sub.3 NH.sub.3 NH.sub.3 NH.sub.3 NH.sub.3 NH3 Temperature ( C.) 100 100 100 100 100 100 100 100 Overpressure (bar) 0 0 0 0 0 0 0 0 Rotational 750 750 750 750 750 750 750 750 speed(revolutions per min) Viscosity (mPa*s) 64 90 115 629 176 41 pH 8.8 8.7 9.04 8.7 9.1 9.01 8.7 Average particle size (m) 2.1 2.3 3.3 6.6 2.4 2.69 Visual inspection A A A A A A A A Seal strength (Al-Al) (N) 6.7 8.0 8.9 7.6 11.8 9.4 4.7 6.5

[0080] EAA #3: dispersible polymer which is an ethylene acrylic acid copolymer (20 wt % comonomer and MFI (190 C./2.16 kg) 300 g/10 min)

[0081] EVA #4: ethylene vinyl acetate, vinyl acetate content 27.0 wt %

[0082] Silica: hydrophilic pyrogenic silica with a specific surface area of 200 m.sup.2/g

[0083] Laponite: synthetic layered phosphate modified silicate with a specific surface area of 330 m.sup.2/g ps *) Comparative Example

[0084] A: Milky dispersion

[0085] B: Milky viscous dispersion

[0086] C: dispersion with discrete particles

[0087] D: High viscous paste