Method for preparing polymer particles

Abstract

The present invention relates to a method for preparing spherical cured polymer particles from a curable composition. The method comprises the steps of: dropping a curable composition onto a substrate having a water contact angle of 150° to 170° at 25° C. to form droplets of the curable composition; and curing the droplets to form the polymer particles.

Claims

1. A method for preparing polymer particles comprising the steps of: dropping a curable composition onto a substrate having a water contact angle of 150° to 170° at 25° C. to form a plurality of droplets of the curable composition; and curing the plurality of droplets to form the polymer particles, wherein the substrate comprises a plurality of semi-spherical engraved patterns, wherein the curable composition is dropped onto the semi-spherical engraved patterns of the substrate such that a ratio percentage (D1/D2*100) of a diameter (D1) of each of the plurality of semi-spherical engraved patterns to a diameter (D2) of each of the plurality of droplets is from 60% to 80%, wherein the polymer particles have a substantially spherical shape, and wherein a minor axis passing through a center of each of the polymer particles is 92% to 100% of a major axis passing through the center of each of the polymer particles.

2. The method for preparing polymer particles according to claim 1, wherein the substrate has a contact angle of 125° to 170° with respect to the curable composition.

3. The method for preparing polymer particles according to claim 1, wherein a ratio percentage (d1/r1*100) of a depth (d1) of each of the plurality of semi-spherical engraved patterns to a radius (r1) of each of the plurality of semi-spherical engraved patterns of the substrate is from 30% to 100%.

4. The method for preparing polymer particles according to claim 1, wherein the curable composition comprises water soluble ethylenically unsaturated monomers, a crosslinking agent and a polymerization initiator.

5. The method for preparing polymer particles according to claim 1, wherein the diameter (D1) of each of the plurality of semi-spherical engraved patterns is from 1500 μm to 2000 μm.

6. The method for preparing polymer particles according to claim 1, wherein the diameter (D2) of each of the droplets is from 2250 μm to 3400 μm.

7. The method for preparing polymer particles according to claim 4, wherein a concentration of the water soluble ethylenically unsaturated monomers is 20 wt. % to 60 wt. % of a total weight of the curable composition.

8. The method for preparing polymer particles according to claim 4, wherein the curable composition further comprises at least one additive selected from the group consisting of a thickener, a plasticizer, a preservation stabilizer and an antioxidant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an image showing the shape of a droplet formed of water having a contact angle of 158°.

(2) FIG. 2 is an image showing the shape of a droplet formed of a curable composition having a contact angle of 164°.

(3) FIG. 3 is a drawing schematically showing the cross section of a substrate, for the explanation of the radius and depth of the semi-spherical engraved pattern formed on the substrate.

(4) FIG. 4 is a graph showing the rate (y axis) of the minor axis to the major axis of the polymer particles, according to the rate (x axis) of the diameter of the semi-spherical engraved pattern to the diameter of the droplet, in the polymer particle prepared in Examples 1 to 6.

(5) FIGS. 5 to 7 are images showing the shapes of the polymer particles prepared in Examples 1, Example 4 and Example 6, respectively.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) Hereinafter, preferable examples are presented for better understanding of the present invention. However, these examples are presented only as the illustrations of the present invention, and the present invention is not limited thereby.

Example 1: Preparation of Polymer Particles

(7) Semi-spherical engraved patterns were formed using an Al substrate as a support base, and using NeverWet SE available from NeverWet, LLC, a primer layer and a top coating layer were formed on the support base. After coating, the diameter of the semi-spherical engraved pattern of the substrate was 1500 μm.

(8) Meanwhile, to 500 g of acrylic acid, 1.5 g of polyethylene glycol diacrylate (PEGDA, molecular weight 400), 0.5 g of trimethylolpropane triacrylate including 9 mol % of ethylene oxide (Ethoxylated-TMPTA, TMP (EO)9TA, M-3190, Miwon Specialty Chemicals Co., Ltd.), and 0.4 g of IRGACURE 819 were added, and 800 g of a 24 wt % caustic soda solution was gradually added dropwise. The mixed solution heated by the neutralization heat was cooled to prepare a curable composition.

(9) And, the diameter according to the volume of the curable composition was obtained as follows

(10) Specifically, each 10 , 8 , 7 , 4 and 2 of the curable composition was dropped on the flat surface of the substrate to form 5 droplets. And, with a contact angle measuring device (model name: DSA100, Manufacturing Company: KRUSS GmbH), for the 5 droplets, the lengths of the major axis were measured at about 25° C., which were determined as the diameters according to the volume of the curable composition. As the result of measurement, the diameter for 10 was 3400 μm, the diameter for 8 was 3000 μm, the diameter for 7 was 2800 μm, the diameter for 4 was 2500 μm, and the diameter for 2 was 2250 μm.

(11) On each semi-spherical engraved pattern of the substrate, each 10 of the curable composition was dropped to form spherical droplets.

(12) From the measurement result of the diameter according to the volume of the curable composition, a rate (D1/D2*100) of the diameter (D1, 1500 μm) of the semi-spherical engraved pattern to the diameter (D2, 3400 μm) of the droplet was calculated to be about 44%.

(13) Thereafter, the droplets were cured by UV irradiation, thus preparing polymer particles.

Example 2: Preparation of Polymer Particles

(14) Polymer particles were prepared by the same method as Example 1, except that 8 of the curable composition was dropped on each semi-spherical engraved pattern of the substrate.

(15) From the measurement result of the diameter according to the volume of the curable composition of Example 1, a rate (D1/D2*100) of the diameter (D1, 1500 μm) of the semi-spherical engraved pattern to the diameter (D2, 3000 μm) of the droplet was calculated to be about 50%.

Example 3: Preparation of Polymer Particles

(16) Polymer particles were prepared by the same method as Example 1, except that 4 of the curable composition was dropped on each semi-spherical engraved pattern of the substrate.

(17) From the measurement result of the diameter according to the volume of the curable composition of Example 1, a rate (D1/D2*100) of the diameter (D1, 1500 μm) of the semi-spherical engraved pattern to the diameter (D2, 2500 μm) of the droplet was calculated to be about 60%.

Example 4: Preparation of Polymer Particles

(18) A substrate on which semi-spherical engraved patterns are formed was manufactured by the same method as Example 1, except that the diameter of the semi-spherical engraved pattern was 2000 μm.

(19) Each 7 of the curable composition identical to that of Example 1 was dropped on each semi-spherical engraved pattern of the substrate, to form spherical droplets.

(20) From the measurement result of the diameter according to the volume of the curable composition of Example 1, a rate (D1/D2*100) of the diameter (D1, 2000 μm) of the semi-spherical engraved pattern to the diameter (D2, 2800 μm) of the droplet was calculated to be about 71%.

(21) Thereafter, the droplets were cured by the same method as Example 1, thus preparing polymer particles.

Example 5: Preparation of Polymer Particles

(22) Polymer particles were prepared by the same method as Example 4, except that each 4 of the curable composition was dropped on each semi-spherical engraved pattern of the substrate.

(23) From the measurement result of the diameter according to the volume of the curable composition of Example 1, a rate (D1/D2*100) of the diameter (D1, 2000 μm) of the semi-spherical engraved pattern to the diameter (D2, 2500 μm) of the droplet was calculated to be about 80%.

Example 6: Preparation of Polymer Particles

(24) Polymer particles were prepared by the same method as Example 4, except that each 2 of the curable composition was dropped on each semi-spherical engraved pattern of the substrate.

(25) From the measurement result of the diameter according to the volume of the curable composition of Example 1, a rate (D1/D2*100) of the diameter (D1, 2000 μm) of the semi-spherical engraved pattern to the diameter (D2, 2250 μm) of the droplet was calculated to be about 89%.

Experimental Example: Confirmation of the Sphericity of Polymer Particles

(26) For the polymer particles prepared in Examples, a rate of the minor axis to the major axis passing through the center was measured, and the results were shown in the following Table 1 and FIG. 4. Theoretically, a complete sphere has identical lengths of the major axis and the minor axis passing through the center, and thus, as a rate of the minor axis to the major axis is closer to 100%, it means that the polymer particle has a shape closer to a complete sphere.

(27) TABLE-US-00001 TABLE 1 Example Example Example Example Example Example 1 2 3 4 5 6 D1/D2*100 44% 50% 60% 71% 80% 89% rate of the 82% 86% 95% 95% 92% 91% minor axis to the major axis

(28) And, the shapes of the polymer particles prepared in Example 1, Example 4 and Example 6 were observed using a contact angle measuring device (model name: DSA100, Manufacturing Company: KRUSS GmbH).

(29) Referring to the Table 1 and FIGS. 4 to 7, it is confirmed that according to the preparation method of one embodiment of the present invention, spherical polymer particles can be provided, and particularly, it is confirmed that in case a rate (D1/D2*100) of the diameter (D1) of a semi-spherical engraved pattern to the diameter (D2) of a droplet is 50% to 90%, polymer particles close to a complete sphere can be provided.