CN114075343B - Hydrophobically modified starch film - Google Patents
Hydrophobically modified starch film Download PDFInfo
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- CN114075343B CN114075343B CN202110957156.9A CN202110957156A CN114075343B CN 114075343 B CN114075343 B CN 114075343B CN 202110957156 A CN202110957156 A CN 202110957156A CN 114075343 B CN114075343 B CN 114075343B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2303/00—Characterised by the use of starch, amylose or amylopectin or of their derivatives or degradation products
- C08J2303/02—Starch; Degradation products thereof, e.g. dextrin
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/15—Heterocyclic compounds having oxygen in the ring
- C08K5/151—Heterocyclic compounds having oxygen in the ring having one oxygen atom in the ring
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W90/00—Enabling technologies or technologies with a potential or indirect contribution to greenhouse gas [GHG] emissions mitigation
- Y02W90/10—Bio-packaging, e.g. packing containers made from renewable resources or bio-plastics
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Abstract
The invention provides a novel hydrophobically modified starch film, which is prepared by adopting a layered multi-casting process, and adopts a three-layer structure which is hydrophobically modified by alkyl ketene dimer and has homogeneous heterogeneous self-enhancement characteristics, wherein the outer layer is hydrophobic, the inner layer provides excellent mechanical properties, the excellent properties of the starch film are maintained to the maximum extent, the hydrophilicity of the starch film is reduced, and the hydrophobic properties of the starch film are improved.
Description
Technical Field
The invention relates to a waterproof starch film, in particular to a waterproof starch film taking alkyl ketene dimer as a modifier and a preparation method thereof, and the waterproof starch film is mainly used in the field of packaging materials.
Background
Starch is widely regarded as a biodegradable material with development potential due to the advantages of abundant reserves, low price, good plasticity, safe use and the like. However, in practical application, a large amount of hydroxyl groups naturally existing in starch and a large amount of plasticizers (such as glycerol, polyethylene glycol and the like) added in the preparation process of the material can cause the starch product to easily absorb moisture in the environment, so that the related product is collapsed and deformed, the mechanical properties are poor, and the use value of the product is seriously affected. Therefore, how to reduce the hydrophilicity of the material and widen the application prospect of the product becomes a key problem to be solved in starch material application.
Alkyl Ketene Dimer (AKD) is a waxy solid, and the molecular structure of the Alkyl Ketene Dimer (AKD) contains a lactone ring with higher chemical activity, can be subjected to esterification reaction with hydroxyl in starch materials to generate beta-ketoester, and achieves the aim of hydrophobicity by converting easily hydrophilic hydroxyl into ester groups. However, direct blending with the starch matrix leads to microscopic phase separation behaviour, which in turn leads to reduced mechanical properties. Therefore, the hydrophobic modified starch film with the self-reinforced structure is prepared by a layered multi-time casting process, and good hydrophobicity and mechanical properties can be obtained at the same time.
Disclosure of Invention
The invention aims to solve the problem that the mechanical property of a film material is reduced due to phase separation behavior generated by direct blending of a hydrophobic substance and starch, and provides a hydrophobic modified starch film and a preparation method thereof. The film is prepared by layering and multi-time casting, and can reduce the hydrophilicity of the starch film and improve the hydrophobic property of the starch film while keeping the excellent property of the starch film to the maximum extent.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a first object of the present invention is to provide a hydrophobically modified starch film wherein the added modifier is an alkyl ketene dimer.
In one or more embodiments, the hydrophobically modified starch film comprises dry starch, water, plasticizer, and the like in a conventional starch film; or alkyl ketene dimer is added in the preparation method of the common starch film to achieve the aim of hydrophobicity.
The second object of the present invention is to provide a method for preparing the hydrophobically modified starch film, comprising the steps of:
(1) Mixing starch with water to prepare a suspension with the concentration of 3-8wt%; adding plasticizer with the weight of 20-40% of the dry starch, and continuously stirring in a constant-temperature water bath kettle with the temperature of 90-95 ℃ until the starch is fully gelatinized; reducing the water bath temperature to 40-70 ℃ while maintaining stirring, adding alkyl ketene dimer, and fully homogenizing the solution after the alkyl ketene dimer is completely melted to obtain starch film forming liquid I;
(2) Casting the starch film forming liquid prepared in the step (1) on a flat plate, and then placing the flat plate in a constant temperature and humidity box for drying for 2-5 hours to obtain a film I clung to the surface of the flat plate;
(3) Repeating the step (1) again without adding alkyl ketene dimer to obtain starch film forming liquid II; pouring the film forming liquid on the first surface of the film in the step (2), uniformly casting, and then placing the film into a constant temperature and humidity box for drying for 5-10 hours to obtain a second film;
(4) Repeating the step (1) again to obtain starch film forming liquid III; pouring the film forming liquid on the second surface of the film in the step (3), uniformly casting, and drying in a constant temperature and humidity box for 12-20 h to obtain a third film;
(5) Taking down the film prepared in the step (4), heating for 1-3 hours at the temperature of 80-140 ℃, and finally taking out and balancing at room temperature to obtain the hydrophobically modified starch film;
wherein the temperature in the constant temperature and humidity box in the steps (2) - (4) is 15-45 ℃ and the relative humidity is 40-80%.
In one or more embodiments, the starch in step (1) is one or more of raw starch, or is one or more of destructurized starch.
Specifically, the raw starch is tapioca starch, potato starch, wheat starch or corn starch; the modified starch is hydroxypropyl corn modified starch, carboxymethyl starch, esterified starch, oxidized starch, acid modified starch, etherified starch, crosslinked starch, cationic starch, grafted starch or dialdehyde starch.
In one or more embodiments, the plasticizer in step (1) is xylitol, sorbitol, mannitol, propylene glycol, glycerol, fructose, sucrose, or glyceryl triacetate.
In one or more embodiments, the homogenizing means in step (1) is any method in the prior art, for example, a high-speed stirring method can be used, the stirring speed is 10000-20000 rpm, and the stirring time is 2-10 min.
In one or more embodiments, the alkyl ketene dimer in step (1) is added in an amount of 4% to 20% by weight of dry starch.
In one or more embodiments, the plate material in step (2) is any one of polystyrene, polytetrafluoroethylene, polyvinyl chloride, or glass.
In one or more embodiments, it is preferable that the film casting amount in steps (2) and (4) is 0.3 to 0.6g/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the The casting quantity of the film forming liquid in the step (3) is 0.5 to 0.8g/cm 2 。
The third object of the invention is the use of the hydrophobically modified starch film obtained by the above-described preparation method in pharmaceuticals, foods or cosmetics. In particular, the hydrophobically modified starch film obtained by the present invention can be used for coating pharmaceuticals, foods or cosmetics.
A fourth object of the present invention is the use of alkyl ketene dimers in the preparation of hydrophobically modified starch films. The alkyl ketene dimer is a waxy solid, and the molecular structure of the alkyl ketene dimer contains a lactone ring with higher chemical activity, can be subjected to esterification reaction with hydroxyl in starch materials to generate beta-ketoester, and achieves the aim of hydrophobicity by converting the hydroxyl which is easy to be hydrophilic into an ester group.
Compared with the prior art, the hydrophobically modified starch film disclosed by the invention is prepared by adopting a layered multi-time casting process, and adopts a three-layer structure which is hydrophobically modified by alkyl ketene dimer and has the characteristics of homogeneous phase and heterogeneous phase self-enhancement, wherein the outer layer is hydrophobic, the inner layer provides excellent mechanical properties, the excellent properties of the starch film are maintained to the maximum extent, the hydrophilicity of the starch film is reduced, and the hydrophobic properties of the starch film are improved.
For a better understanding and implementation, the present invention is described in detail below with reference to the drawings.
Drawings
Fig. 1: the preparation step flow chart of the hydrophobically modified starch film is provided.
Detailed Description
The invention aims to solve the problem that the mechanical property of a film material is reduced due to phase separation behavior generated by direct blending of a hydrophobic substance and starch, and provides a hydrophobic modified starch film and a preparation method thereof. The film is prepared by layering and multi-time casting, and can reduce the hydrophilicity of the starch film and improve the hydrophobic property of the starch film while keeping the excellent property of the starch film to the maximum extent.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a first object of the present invention is to provide a hydrophobically modified starch film wherein the added modifier is an alkyl ketene dimer.
In one or more embodiments, the hydrophobically modified starch film comprises dry starch, water, plasticizer, and the like in a common starch film; or alkyl ketene dimer is added in the preparation method of the common starch film to achieve the aim of hydrophobicity.
A second object of the present invention is to provide a method for preparing the hydrophobically modified starch film (as shown in fig. 1), comprising the steps of:
(1) Mixing starch with water to prepare a suspension with the concentration of 3-8wt%; adding plasticizer with the weight of 20-40% of the dry starch, and continuously stirring in a constant-temperature water bath kettle with the temperature of 90-95 ℃ until the starch is fully gelatinized; reducing the water bath temperature to 40-70 ℃ while maintaining stirring, adding alkyl ketene dimer, and fully homogenizing the solution after the alkyl ketene dimer is completely melted to obtain starch film forming liquid I;
(2) Casting the starch film forming liquid prepared in the step (1) on a flat plate, and then placing the flat plate in a constant temperature and humidity box for drying for 2-5 hours to obtain a film I clung to the surface of the flat plate;
(3) Repeating the step (1) again without adding alkyl ketene dimer to obtain starch film forming liquid II; pouring the film forming liquid on the first surface of the film in the step (2), uniformly casting, and then placing the film into a constant temperature and humidity box for drying for 5-10 hours to obtain a second film;
(4) Repeating the step (1) again to obtain starch film forming liquid III; pouring the film forming liquid on the second surface of the film in the step (3), uniformly casting, and drying in a constant temperature and humidity box for 12-20 h to obtain a third film;
(5) Taking down the film prepared in the step (4), heating for 1-3 hours at the temperature of 80-140 ℃, and finally taking out and balancing at room temperature to obtain the hydrophobically modified starch film;
wherein the temperature in the constant temperature and humidity box in the steps (2) - (4) is 15-45 ℃ and the relative humidity is 40-80%.
In one or more embodiments, the starch in step (1) is one or more of raw starch, or is one or more of modified starch.
Specifically, the raw starch is tapioca starch, potato starch, wheat starch or corn starch; the modified starch is hydroxypropyl corn modified starch, carboxymethyl starch, esterified starch, oxidized starch, acid modified starch, etherified starch, crosslinked starch, cationic starch, grafted starch or dialdehyde starch.
In one or more embodiments, the plasticizer in step (1) is xylitol, sorbitol, mannitol, propylene glycol, glycerol, fructose, sucrose, or glyceryl triacetate.
In one or more embodiments, the homogenizing means in step (1) is any method in the prior art, for example, a high-speed stirring method may be used, the stirring speed is 10000-20000 rpm, and the stirring time is 2-10 min.
In one or more embodiments, the alkyl ketene dimer in step (1) is added in an amount of 4% to 20% by weight of the dry starch.
In one or more embodiments, the plate in the step (2) is made of any one of polystyrene, polytetrafluoroethylene, polyvinyl chloride or glass.
In one or more embodiments, preferably, the film casting amount in steps (2) and (4) is 0.3 to 0.6g/cm2; the casting quantity of the film in the step (3) is 0.5-0.8 g/cm < 2 >.
The third object of the invention is the use of the hydrophobically modified starch film obtained by the above-described preparation method in pharmaceuticals, foods or cosmetics. In particular, the hydrophobically modified starch film obtained by the present invention can be used for coating pharmaceuticals, foods or cosmetics.
A fourth object of the present invention is the use of alkyl ketene dimers in the preparation of hydrophobically modified starch films. The alkyl ketene dimer is a waxy solid, and the molecular structure of the alkyl ketene dimer contains a lactone ring with higher chemical activity, can be subjected to esterification reaction with hydroxyl in starch materials to generate beta-ketoester, and achieves the aim of hydrophobicity by converting the hydroxyl which is easy to be hydrophilic into an ester group.
All materials, reagents and equipment selected for use in the present invention are well known in the art, but are not limiting of the practice of the invention, and other reagents and equipment known in the art may be suitable for use in the practice of the following embodiments of the invention.
Example 1
A hydrophobically modified starch film is prepared by the following method:
(1) Mixing common corn starch (commercially available) with water to obtain suspension with concentration of 4wt%, adding appropriate amount of glycerol (20wt% of dry weight of starch), and continuously stirring in a constant temperature water bath kettle at 95deg.C until starch is fully gelatinized; maintaining stirring while reducing the water bath temperature to 50deg.C, adding alkyl ketene dimer (8wt% of dry weight of starch) (Kuer chemical Co., ltd.), and stirring the solution at 10000rpm for 3min after it is completely melted;
(2) Taking 30g of the film forming liquid prepared in the step (1), casting the film forming liquid on a polytetrafluoroethylene (Shanghai barrier instruments Co., ltd.) flat plate with the diameter of 11cm, and then placing the flat plate in a constant temperature and humidity box with the relative humidity of 50% and the temperature of 20 ℃ for drying for 3.5h to form a film and tightly attaching the film to the surface of the flat plate;
(3) Preparing the starch film-forming liquid in the step (1) again, wherein alkyl ketene dimer is not added; pouring 40g of the film forming liquid on the surface of the film in the step (2), uniformly casting, and then putting the film forming liquid into a constant temperature and humidity box with 50% of relative humidity and 20 ℃ for drying for 8 hours to form a film;
(4) Preparing the film forming liquid in the step (1) again, pouring 30g of the film forming liquid onto the surface of the film in the step (3) and uniformly casting, and putting the film forming liquid into a constant temperature and humidity box with 50% of relative humidity and 20 ℃ to dry for 15 hours to form a film;
(5) Taking down the film prepared in the step (4), heating at a high temperature of 120 ℃ for 3 hours in an oven, and finally taking out and balancing at room temperature.
Example 2
A hydrophobically modified starch film is prepared by the following method:
(1) Mixing potato starch (commercially available) with water to obtain suspension with concentration of 6wt%, adding appropriate amount of glycerol (30wt% of dry weight of starch), and continuously stirring in a constant-temperature water bath kettle at 95deg.C until starch is fully gelatinized; maintaining stirring while reducing the water bath temperature to 60 ℃, adding alkyl ketene dimer (12 wt% of dry weight of starch), and stirring the solution at 14000rpm for 2min after the alkyl ketene dimer is completely melted;
(2) Casting 30g of the film forming liquid prepared in the step (1) on a polystyrene (Shanghai Hirudo scientific instrument Co., ltd.) flat plate with the diameter of 11cm, and then drying in a constant temperature and humidity box with the relative humidity of 40% and the temperature of 25 ℃ for 2.5h to form a film and cling to the surface of the flat plate;
(3) Preparing the starch film-forming liquid in the step (1) again, wherein alkyl ketene dimer is not added; pouring 40g of the film forming liquid on the surface of the film in the step (2), uniformly casting, and then putting the film forming liquid into a constant temperature and humidity box with 40% of relative humidity and 25 ℃ to be dried for 6.5 hours to form a film;
(4) Preparing the film forming liquid in the step (1) again, pouring 30g of the film forming liquid onto the surface of the film in the step (3) and uniformly casting, and putting the film forming liquid into a constant temperature and humidity box with 40% of relative humidity and 25 ℃ to dry for 18 hours to form a film;
(5) Taking down the film prepared in the step (4), heating in an oven at a high temperature of 140 ℃ for 1h, and finally taking out and balancing at room temperature.
Example 3
A hydrophobically modified starch film is prepared by the following method:
(1) Mixing high-amylose hydroxypropyl starch with water to obtain suspension with concentration of 7wt%, adding appropriate amount of mannitol (24 wt% of dry weight of starch), and continuously stirring in a constant-temperature water bath kettle at 95deg.C until starch is fully gelatinized; maintaining stirring while reducing the water bath temperature to 65 ℃, adding alkyl ketene dimer (16 wt% of dry weight of starch), and stirring the solution at 15000rpm for 1min after the alkyl ketene dimer is completely melted;
(2) Taking 35g of the film forming liquid prepared in the step (1), casting the film forming liquid on a polyvinyl chloride (Lei Qi experiment equipment Co., hangzhou) flat plate with the diameter of 11cm, and then drying the flat plate in a constant temperature and humidity box with the relative humidity of 65% and the temperature of 40 ℃ for 2 hours to form a film and tightly attaching the film to the surface of the flat plate;
(3) Preparing the starch film-forming liquid in the step (1) again, wherein alkyl ketene dimer is not added; pouring 40g of the film forming liquid on the surface of the film in the step (2), uniformly casting, and then putting the film forming liquid into a constant temperature and humidity box with 65% of relative humidity and 40 ℃ to dry for 5.5 hours to form a film;
(4) Preparing the film forming liquid in the step (1) again, pouring 30g of the film forming liquid onto the surface of the film in the step (3) and uniformly casting, and putting the film forming liquid into a constant temperature and humidity box with 65% of relative humidity and 40 ℃ to dry for 13 hours to form a film;
(5) Taking down the film prepared in the step (4), heating in an oven at a high temperature of 130 ℃ for 2 hours, and finally taking out and balancing at room temperature.
Example 4
A hydrophobically modified starch film is prepared by the following method:
(1) Mixing carboxymethyl starch with water to obtain suspension with concentration of 5wt%, adding appropriate amount of propylene glycol (35 wt% accounting for dry weight of starch), and continuously stirring in a constant temperature water bath kettle at 95deg.C until starch is fully gelatinized; maintaining stirring while reducing the water bath temperature to 65 ℃, adding alkyl ketene dimer (20 wt% of dry weight of starch), and stirring the solution at 15000rpm for 1min after the alkyl ketene dimer is completely melted;
(2) Taking 35g of the film forming liquid prepared in the step (1), casting the film forming liquid on a polytetrafluoroethylene flat plate with the diameter of 11cm, and then placing the flat plate in a constant temperature and humidity box with the relative humidity of 55% and the temperature of 50 ℃ for drying for 2 hours, so that the flat plate is formed into a film and is tightly attached to the surface of the flat plate;
(3) Preparing the starch film-forming liquid in the step (1) again, wherein alkyl ketene dimer is not added; pouring 40g of the film forming liquid on the surface of the film in the step (2), uniformly casting, and then putting the film forming liquid into a constant temperature and humidity box with 55% of relative humidity and 50 ℃ for drying for 5 hours to form a film;
(4) Preparing the film forming liquid in the step (1) again, pouring 30g of the film forming liquid onto the surface of the film in the step (3) and uniformly casting, and drying the film forming liquid in a constant temperature and humidity box with 55% of relative humidity and 50 ℃ for 12 hours to form a film;
(5) Taking down the film prepared in the step (4), heating in an oven at a high temperature of 130 ℃ for 2 hours, and finally taking out and balancing at room temperature.
Comparative example 1
A starch film prepared by the method comprising:
mixing common corn starch with water to prepare a suspension with the concentration of 6wt%, adding a proper amount of glycerin (20 wt% accounting for dry weight of the starch) and continuously stirring in a constant-temperature water bath kettle at 95 ℃ until the starch is fully gelatinized; 35g of film forming liquid is cast on a polytetrafluoroethylene flat plate with the diameter of 11cm, and then the film forming liquid is placed in a constant temperature and humidity box with the relative humidity of 55 percent and the temperature of 50 ℃ for drying for 15 hours, so that a pure starch film without adding alkyl ketene dimer is obtained.
Comparative example 2
A starch film prepared by the method comprising:
mixing common corn starch with water to prepare a suspension with the concentration of 6wt%, adding a proper amount of glycerin (20 wt% accounting for dry weight of the starch) and continuously stirring in a constant-temperature water bath kettle at 95 ℃ until the starch is fully gelatinized; maintaining stirring while reducing the water bath temperature to 65 ℃, adding alkyl ketene dimer (8 wt% of dry weight of starch), stirring the solution at 15000rpm for 1min to obtain a film forming solution after the alkyl ketene dimer is completely melted, casting 35g of the film forming solution on a polytetrafluoroethylene flat plate with the diameter of 11cm, drying in a constant temperature and humidity box with the relative humidity of 55% and the temperature of 50 ℃ for 15h to volatilize water, and heating at the high temperature of 120 ℃ for 3h to prepare the direct blending film.
Test case
The method for testing the film strength in the embodiment comprises the following steps: according to GB13022-91, film samples are first placed in a constant temperature and humidity cabinet at 25℃and 53% relative humidity for three days to equilibrate together prior to testing. For testing, smooth and flat film samples were cut into dumbbell-shaped test bars (35 mm. Times.2 mm) using a special cutter. The test was performed using an INSTRONT 5566 universal material tester (instron, usa) with a tensile clamp initial spacing of 25mm, a weighing sensor sensitivity of 0.1N, a set tensile speed of 5mm/min, and the instrument clamp automatically reset after the sample strip had been broken by stretching. Each sample was tested in 7 replicates and the Elongation At Break (EAB) and Tensile Strength (TS) of the sample were recorded.
The test method for breaking elongation of the embodiment comprises the following steps: as above
The method for testing the water absorption rate in the embodiment comprises the following steps: according to GB/T1034-2008, the sample film is cut into square shapes with the length and width of 61+/-1 mm, and then is put into a 50.0+/-2.0 ℃ oven for drying until the weight is constant (the mass change is within +/-0.1 mg). The dried samples were placed in a constant temperature and humidity cabinet at 23℃and 50% relative humidity, and after 24 hours, each sample (accurate to 0.1 mg) was weighed. Each sample was assayed in triplicate and the water uptake mass fraction of the sample relative to the initial mass was calculated according to equation 2-3:
c＝(m 2 -m 1 )/m 1 ×100％ (2-3)
wherein m is 2 And m 1 The mass of the sample after and before moisture absorption, respectively.
The test method of the surface contact angle in this embodiment is as follows: 3 mu L of deionized water is dripped on the surface of a sample film by using a DCA20 contact angle meter, a digital camera is used for photographing the water drop at 0s just after the water drop falls and 60s after the water drop is contacted, a three-phase contact point, a vertex, an upper left point and an upper right point of the water drop are selected by using a manual measurement method for outline hooking, and then the angle between a solid-liquid-gas three-phase tangent line and a liquid-solid contact base line is automatically calculated to be a static contact angle. And 5 measuring points are selected for each sample to be tested, and finally, the contact angle value of the sample surface is obtained.
The main properties of the starch films of the examples and the comparative examples are as follows:
as can be seen from the above table, compared with the starch films of comparative example 1, examples 1 to 4 and comparative example 2, after different amounts of alkyl ketene dimer were added, the water absorption of the film was significantly reduced, and the surface contact angle was significantly increased, because the alkyl ketene dimer was esterified with the hydroxyl groups of the starch, and the hydrophobicity of the starch film was improved; compared with the direct blending casting of the comparative example 2, the novel starch film prepared by the layered multi-casting method has stronger mechanical properties, the tensile strength and the elongation at break of the novel starch film are obviously changed from those of the pure starch film, the water absorption rate and the surface contact angle are not greatly different, and the hydrophobicity can be obviously improved while the mechanical properties of the starch film are maintained.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (8)
1. The preparation method of the hydrophobically modified starch film is characterized in that the added modifier is alkyl ketene dimer, and the preparation method comprises the following steps:
(1) Mixing starch with water to prepare a suspension with the concentration of 3-8wt%; adding plasticizer with the weight of 20-40% of the dry starch, and continuously stirring in a constant-temperature water bath kettle with the temperature of 90-95 ℃ until the starch is fully gelatinized; reducing the water bath temperature to 40-70 ℃ while maintaining stirring, adding alkyl ketene dimer, and fully homogenizing the solution after the alkyl ketene dimer is completely melted to obtain starch film forming liquid I;
(2) Casting the starch film forming liquid prepared in the step (1) on a flat plate, and then placing the flat plate in a constant temperature and humidity box for drying for 2-5 hours to obtain a film I clung to the surface of the flat plate;
(3) Repeating the step (1) again without adding alkyl ketene dimer to obtain starch film forming liquid II; pouring the film forming liquid on the first surface of the film in the step (2), uniformly casting, and then placing the film into a constant temperature and humidity box for drying for 5-10 hours to obtain a second film;
(4) Repeating the step (1) again to obtain starch film forming liquid III; pouring the film forming liquid on the second surface of the film in the step (3), uniformly casting, and drying in a constant temperature and humidity box for 12-20 h to obtain a third film;
(5) Taking down the film prepared in the step (4), heating for 1-3 hours at the temperature of 80-140 ℃, and finally taking out and balancing at room temperature to obtain the hydrophobically modified starch film;
wherein the temperature in the constant temperature and humidity box in the steps (2) - (4) is 15-45 ℃ and the relative humidity is 40-80%.
2. The hydrophobically modified starch film of claim 1, wherein the starch in step (1) is one or more of raw starch or is one or more of modified starch.
3. The hydrophobically modified starch film of claim 2, wherein the raw starch is tapioca starch, potato starch, wheat starch or corn starch; the modified starch is hydroxypropyl corn modified starch, carboxymethyl starch, esterified starch, oxidized starch, acid modified starch, etherified starch, crosslinked starch, cationic starch, grafted starch or dialdehyde starch.
4. The hydrophobically modified starch film of claim 1, wherein the plasticizer in step (1) is xylitol, sorbitol, mannitol, propylene glycol, glycerol, fructose, sucrose or glyceryl triacetate.
5. The hydrophobically modified starch film of claim 1 wherein the alkyl ketene dimer is added in step (1) in an amount of 4% to 20% by weight of dry starch.
6. The hydrophobically modified starch film of claim 1, wherein the flat sheet material in step (2) is polystyrene, polytetrafluoroethylene, polyvinylchloride or glass.
7. The hydrophobically modified starch film of claim 1, wherein the film casting volume in steps (2) and (4) is from 0.3 to 0.6g/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the The casting quantity of the film forming liquid in the step (3) is 0.5 to 0.8g/cm 2 。
8. Use of the hydrophobically modified starch film according to any one of claims 1 to 7 in medicine, food or cosmetics.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110957156.9A CN114075343B (en) | 2021-08-19 | 2021-08-19 | Hydrophobically modified starch film |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110957156.9A CN114075343B (en) | 2021-08-19 | 2021-08-19 | Hydrophobically modified starch film |
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| CN101230151A (en) * | 2007-12-28 | 2008-07-30 | 北京航空航天大学 | High-fluidity and strong-hydrophobicity starch and preparation method thereof |
| CN101328285A (en) * | 2008-01-25 | 2008-12-24 | 陕西科技大学 | Preparation of hydrophobical thermoplastic starch |
| CN103302708A (en) * | 2013-05-08 | 2013-09-18 | 广东省宜华木业股份有限公司 | Preparation method of novel hydrophobic wood |
| CN103757980A (en) * | 2014-01-03 | 2014-04-30 | 金华盛纸业（苏州工业园区）有限公司 | Latex for papermaking, preparation method and coating containing latex for papermaking |
| CN111621046A (en) * | 2020-06-09 | 2020-09-04 | 施塔希(绍兴)新材料有限公司 | Waterproof starch film with biodegradable polyurethane as coating and preparation method thereof |
| CN112790456A (en) * | 2020-12-29 | 2021-05-14 | 无锡市圣华盾医疗科技有限公司 | Waterproof moisture-permeable medical protective clothing and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI668265B (en) * | 2018-08-10 | 2019-08-11 | 衍鋐機械股份有限公司 | Hydrophobic thermoplastic starch and method for manufacturing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101230151A (en) * | 2007-12-28 | 2008-07-30 | 北京航空航天大学 | High-fluidity and strong-hydrophobicity starch and preparation method thereof |
| CN101328285A (en) * | 2008-01-25 | 2008-12-24 | 陕西科技大学 | Preparation of hydrophobical thermoplastic starch |
| CN103302708A (en) * | 2013-05-08 | 2013-09-18 | 广东省宜华木业股份有限公司 | Preparation method of novel hydrophobic wood |
| CN103757980A (en) * | 2014-01-03 | 2014-04-30 | 金华盛纸业（苏州工业园区）有限公司 | Latex for papermaking, preparation method and coating containing latex for papermaking |
| CN111621046A (en) * | 2020-06-09 | 2020-09-04 | 施塔希(绍兴)新材料有限公司 | Waterproof starch film with biodegradable polyurethane as coating and preparation method thereof |
| CN112790456A (en) * | 2020-12-29 | 2021-05-14 | 无锡市圣华盾医疗科技有限公司 | Waterproof moisture-permeable medical protective clothing and manufacturing method thereof |
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