A method of thermoforming a carrageenan film material

Abstract

The application discloses a hot-pressing forming preparation method of carrageenan film material. The carrageenan, water and inorganic salt solution are uniformly mixed and then are loaded into a mold for hot-pressing forming. The carrageenan is processed and formed through the hot-pressing method, because the carrageenan can be dissolved in hot water, under the action of temperature and pressure, water molecules can destroy the mutual action between the molecules of the carrageenan, so that the carrageenan is melted and thermoplastic; meanwhile, the carrageenan can form cross-linking structures with different ions (Na + , Mg 2+ and Ca 2+ , etc.) in the forming process, so that the mechanical strength of the carrageenan material can be regulated. Compared with a solution method, the hot-pressing method has the advantages of less solution consumption, simple steps and no need for or simple post-treatment, and is an ideal processing method for the application of the carrageenan material.

Description

Technical Field

[0001] This invention relates to the field of carrageenan film material technology, and in particular to a hot pressing method for preparing carrageenan film materials. Background Technology

[0002] Carrageenan, a sulfated polysaccharide polymer extracted from marine red algae, is a soluble, macromolecular polysaccharide hydrophilic colloid. Its molecules contain numerous hydroxyl groups, giving it excellent solubility, gelling properties, and hydrophilicity. Carrageenan has a wide range of applications in detergents, cosmetics, and food additives. The properties of different types of carrageenan vary significantly depending on the ionic solution. For example, type K carrageenan forms a hard gel with potassium ions, while type I carrageenan forms a soft, elastic gel with calcium ions. Therefore, by adding different types of ionic solutions, carrageenan gel materials with varying properties can be obtained. Carrageenan is also frequently blended with other natural polymers to improve or regulate their properties.

[0003] Currently, the main methods for preparing carrageenan materials include solution methods, electrospinning methods, and sol-gel methods. Although these methods are convenient to operate and have simple steps, they use a large amount of solvent during the reaction, have complicated post-processing, and are prone to pollution. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a hot pressing method for preparing carrageenan film materials.

[0005] The present invention discloses a method for preparing carrageenan film material by hot pressing, wherein carrageenan, water and inorganic salt solution are uniformly mixed and then loaded into a mold for hot pressing.

[0006] Furthermore, the carrageenan is of type K, type I, and type L.

[0007] Furthermore, the mass ratio of carrageenan to water is 1:0.8-1.2.

[0008] Furthermore, the inorganic salt solution is one or more of sodium chloride solution, magnesium chloride solution, or calcium chloride solution.

[0009] Furthermore, the concentration of the inorganic salt solution is 0.1-0.2 g / L, and the mass-to-volume ratio of the inorganic salt solution to the sum of the masses of carrageenan and water is 4:0.1-50 g / μL.

[0010] Furthermore, the hot-pressing temperature is 70-90℃, and the hot-pressing time is 3-5 minutes.

[0011] This invention processes carrageenan into shape through hot pressing. This is because carrageenan is soluble in hot water; under the influence of temperature and pressure, water molecules can disrupt the intermolecular interactions of carrageenan, causing it to melt and thermoplasticize. Simultaneously, during the hot pressing process, carrageenan can react with different ions (Na+, Na ... + Mg 2+ and Ca 2+ The hot-pressing method (etc.) forms a cross-linked structure, thereby allowing for the control of the mechanical strength of carrageenan materials. Compared with the solution method, the hot-pressing method uses less solution, involves simpler steps, and requires little or no post-treatment, making it a more ideal processing method for carrageenan materials. Attached Figure Description

[0012] Figure 1 Carrageenan film materials prepared under different processing conditions in Example 1;

[0013] Figure 2a Tensile strength test diagrams for type I carrageenan film materials with various ionic solutions added;

[0014] Figure 2b Elongation at break test diagram for type I carrageenan film materials with various ionic solutions added. Detailed Implementation

[0015] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0016] Example 1

[0017] Prepare a 0.1 g / L sodium chloride inorganic salt ion solution. Mix carrageenan (type K and type I), the ion solution, and water thoroughly. Pour the mixture into a mold, and then place the mold in a hot press for hot pressing. The ratio of carrageenan to aqueous solution is 1:0.8, with a total volume of 4 g; the volume of inorganic salt ions is 10 μL. The hot pressing temperature is 90℃, the pressure is 40 MPa, and the time is 5 min. After hot pressing, cool with water to obtain the carrageenan film material.

[0018] Figure 1 Carrageenan membrane materials under different processing conditions. (a) Carrageenan with pure water; (b) K-type carrageenan with added Na ions; (c) I-type carrageenan composite membrane slices with added Na ions.

[0019] like Figure 1As shown in (a), when carrageenan is mixed with pure water, a uniform and transparent film can be formed by hot pressing, indicating that carrageenan can be thermoplasticized under the action of water. After adding ionic solutions (b and c), although carrageenan can form films, the properties of different types of carrageenan differ significantly. The film material formed by type K carrageenan is brittle and fragile, while type I carrageenan material is transparent and uniform with better mechanical properties, indicating that ionic solutions have a significant impact on the mechanical properties of carrageenan materials. For type K carrageenan, the addition of Na ion solution produces a strong hydration reaction with water molecules, reducing the number of free water molecules and weakening the electrostatic and hydrogen bonding interactions between the ionic chains of type K carrageenan and water molecules, thus affecting the film-forming properties of type K carrageenan. In contrast, type I carrageenan can form a strong interaction with Na ion solution, thereby increasing the mechanical properties of the material.

[0020] Example 2

[0021] The preparation method is the same as in Example 1, except that type I carrageenan is used, and the ionic solutions are sodium chloride, magnesium chloride, and calcium chloride, respectively. The concentration of the ionic solution is 0.1 g / L, and the amount used is 0-50 μL.

[0022] Performance testing

[0023] The obtained carrageenan film material was equilibrated for two weeks in a constant humidity chamber at room temperature and 60% RH, and then subjected to tensile testing on a tensile testing machine (6P-Ts 2000s, Shenzhen Gaopin Testing Equipment Co., Ltd.). According to ASTM D 882-81, the tensile speed was set to 5 mm min⁻¹, and the clamping length was 40 mm. After the material fractured, its fracture strength (σb, MPa) and fracture growth rate (εb, %) were obtained. Five measurements were taken for each sample group, and the average value was calculated. The test results are shown in Figure 2.

[0024] Figure 2a Tensile strength test diagrams for type I carrageenan film materials with various ionic solutions added; Figure 2b Elongation at break test diagram for type I carrageenan film materials with various ionic solutions added.

[0025] As shown in Figure 2, with increasing salt ion solution concentration, the elongation at break and tensile strength of the Na-ion and Mg-ion modified materials initially increased and then decreased, reaching their highest mechanical properties at 30 μL (Na ions) and 40 μL (Mg ions), respectively. The strength of the Ca-ion modified carrageenan film material initially increased and then decreased, reaching its highest tensile strength at 30 μL, while the elongation at break continuously increased with increasing ion concentration. These results indicate that the mechanical properties of carrageenan can be improved to a certain extent through interaction with different ions.

[0026] For any points not covered above, existing technologies shall apply.

[0027] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing carrageenan film material by hot pressing, characterized in that, Carrageenan, water, and an inorganic salt solution are uniformly mixed, placed into a mold, and then hot-pressed. The mass ratio of carrageenan to water is 1:0.8-1.

2. The inorganic salt solution is one of sodium chloride, magnesium chloride, or calcium chloride. The concentration of the inorganic salt solution is 0.1-0.2 g / L, and the mass-to-volume ratio of the sum of the masses of carrageenan and water to the inorganic salt solution is 4:0.1-50 g / μL. The hot-pressing temperature is 70-90℃, and the hot-pressing time is 3-5 min. The carrageenan is of type K, type I, and type L.

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