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EP-4074762-B1 - SUPER ABSORBENT POLYMER FILM AND PREPARATION METHOD THEREOF

EP4074762B1EP 4074762 B1EP4074762 B1EP 4074762B1EP-4074762-B1

Inventors

  • YOON, Kiyoul
  • JOO, Hyosook
  • KANG, Seongkyun
  • KIM, YU JIN
  • KIM, Gicheul
  • CHOI, HYEON

Dates

Publication Date
20260506
Application Date
20210323

Claims (10)

  1. A super absorbent polymer film, obtainable by the method of claim 6, comprising a polymer in which an acrylic acid-based monomer having at least partially neutralized acidic groups is polymerized in the presence of a cellulose-based thickener and a moisturizing agent, wherein a thickness is 0.001 to 0.5 mm, a centrifugal retention capacity (CRC) is 25 g/g or more when measured in accordance with EDANA WSP 241.2, and an elongation calculated by the following Equation 1 is 100% or more: Elongation % = L 1 − L 0 / L 0 * 100 in Equation 1, L 0 is an initial gage length, and L 1 is a gage length at fracture when a specimen is pulled at a rate of 0.5 mm per minute, wherein the elongation is measured as disclosed in the specification.
  2. The super absorbent polymer film of Claim 1, wherein the centrifugal retention capacity (CRC) is 25 g/g to 50 g/g, and the elongation is 100% to 550%.
  3. The super absorbent polymer film of Claim 1, wherein an expansion anisotropy represented by the following Equation 2 is 1.5 or more, when the super absorbent polymer film cut into a circular shape is immersed in 0.9 wt% sodium chloride aqueous solution and swollen for 60 minutes, followed by measuring thicknesses and diameters, Expansion anisotropy = h ′ / h d ′ / d in Equation 2, h is an initial thickness of the super absorbent polymer film, and h' is a thickness after swelling, and d is an initial diameter of the super absorbent polymer film, and d' is a diameter after swelling.
  4. The super absorbent polymer film of Claim 3, wherein the expansion anisotropy is 1.5 to 5.
  5. The super absorbent polymer film of Claim 1, wherein a total light transmittance is 89.5% or more, wherein the total light transmittance is measured as disclosed in the specification.
  6. A preparation method of the super absorbent polymer film of Claim 1, comprising the steps of: preparing a monomer composition by mixing an acrylic acid-based monomer having at least partially neutralized acidic groups, a cellulose-based thickener, a moisturizing agent, a polymerization initiator, and a solvent; casting the monomer composition on a substrate to form a monomer composition film; forming a hydrogel polymer film by irradiating heat and/or light while drawing the monomer composition film; and drying the hydrogel polymer film, wherein the cellulose-based thickener is contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the solid content in the monomer composition, and the moisturizing agent is contained in an amount of 5 to 70 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.
  7. The preparation method of the super absorbent polymer film of Claim 6, wherein the cellulose-based thickener is at least one selected from the group consisting of nanocellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, and sodium carboxymethylcellulose.
  8. The preparation method of the super absorbent polymer film of Claim 6, wherein the moisturizing agent is at least one selected from the group consisting of glycerin; diglycerin; ethylene glycol; propylene glycol; butylene glycol; sorbitol; polyethylene glycol; polyglycerin-3; polyglycerin-6; polyglycerin-10; an ester compound of polyglycerin-10 and a C3 to C18 saturated fatty acid; citric acid; triethyl citrate; methyl citrate; sodium citrate; and trisodium 2-methylcitrate.
  9. The preparation method of the super absorbent polymer film of Claim 6, wherein the monomer composition has a viscosity at 25 °C of 100 mPa·s or more, wherein the viscosity is measured as disclosed in the specification.
  10. The preparation method of the super absorbent polymer film of Claim 6, wherein tension applied to the monomer composition film in the step of forming the hydrogel polymer film is 40 to 100 N/m.

Description

[TECHNICAL FIELD] The present disclosure relates to a super absorbent polymer film and a preparation method of the same. [BACKGROUND OF ART] A super absorbent polymer (SAP) is a type of synthetic polymeric material capable of absorbing 500 to 1000 times its own weight of moisture. Various manufacturers have denominated it with different names, such as SAM (Super Absorbency Material), AGM (Absorbent Gel Material). Such super absorbent polymers started to be practically applied in sanitary products, and they are now being widely used not only for hygiene products such as disposable diapers for children, sanitary napkins, etc., but also for water retaining soil products for gardening, water stop materials for the civil engineering and construction, sheets for raising seedling, fresh-keeping agents for food distribution fields, or materials for poultices. In general, hygiene products such as various diapers, sanitary napkins, or pads for urinary incontinence include an absorber containing super absorbent polymer particles. It was common that the absorber mainly includes the super absorbent polymer particles and fluff pulp to properly fasten the super absorbent polymer particles while maintaining the shape of the absorber and hygiene products. However, due to the presence of the fluff pulp, it was difficult to make the absorber and hygiene products slim and thin, and there was a problem such as poor wearability in which wearer's skin against the hygiene product becomes sweaty. Moreover, since the fluff pulp is mainly obtained from wood as a raw material, it has been contrary to the recent environmental protection trend, and the use of the fluff pulp has become one of the main reasons of increasing manufacturing costs of sanitary products. In addition, current super absorbent polymers are mostly manufactured and used in the form of powder. This powder-type super absorbent polymer has limitation in the range of use and thinning, because it may be scattered or leaked when manufacturing sanitary materials or in actual use and should be used with a specific type of substrate. Further, since absorption performance of the absorber may vary depending on the content distribution of the super absorbent polymer particles, it is difficult to uniformly control the absorption characteristics. Meanwhile, in order to solve the above problems, a sheet-type super absorbent polymer has been proposed. For example, a method for preparing a sheet-type super absorbent polymer by kneading an acrylic acid-based monomer or pulverizing a hydrogel polymer obtained after polymerization to obtain a particulate hydrogel polymer, followed by molding is known. However, since a diameter of the hydrogel polymer particles is 0.2 to 2.0 mm, the above method had a limitation in providing an ultra-thin sheet having a thickness of 0.5 mm or less, and there was a problem in that an auxiliary substance such as fluff pulp is still required to secure shape retention and absorbency. Accordingly, there is a need for research on a new type of super absorbent polymer, which does not require an auxiliary substance such as fluff pulp, can be reduced in thickness, and exhibits excellent absorption properties, and a preparation method of the same. [Prior Art Documents] Patent Document 1: Japanese Patent Application Laid-Open No. Hei 08-73507Patent Document 2: Japanese Patent Application Laid-Open No. Hei 09-183856 EP 3 708 608 A1 discloses a superabsorbent polymer film with centrifugal retention capacity of 10-40 g/g and a moisture content of 10-40 wt.% and having a thickness as low as 0.1 mm, which is prepared by a process comprising the steps of (i) preparing a monomer composition by mixing an acrylic acid-based monomer having at least partially neutralized acidic groups, a moisturizing agent, an internal crosslinking agent and a solvent; (ii) forming a hydrogel polymer film and thermally polymerizing or photopolymerizing the monomer composition to form a hydrogel polymer; and (iii) drying the hydrogel polymer film. [DETAILED DESCRIPTION OF THE INVENTION] [Technical Problem] In order to solve the above problems, there are provided a film-type super absorbent polymer capable of replacing the existing powder-type super absorbent polymer, and a preparation method of the same. [Technical Solution] According to an embodiment of the present disclosure, there is provided a super absorbent polymer film, obtainable by the method of the present invention, including a polymer in which an acrylic acid-based monomer having at least partially neutralized acidic groups is polymerized in the presence of a cellulose-based thickener and a moisturizing agent, wherein a thickness is 0.001 to 0.5 mm,a centrifugal retention capacity (CRC) is 25 g/g or more when measured in accordance with EDANA WSP 241.2, andan elongation calculated by the following Equation 1 is 100% or more: Elongation%=L1−L0/L0*100in Equation 1,L0 is an initial gage length, andL1 is a gage length at fracture when