CN112812479B

CN112812479B - Biodegradable thermoplastic PVA/starch seed tape and preparation method thereof

Info

Publication number: CN112812479B
Application number: CN202110160134.XA
Authority: CN
Inventors: 李颖熙
Original assignee: Zhongshan Xinlinghang Plastic Technology Co ltd
Current assignee: Zhongshan Xinlinghang Plastic Technology Co ltd
Priority date: 2021-02-05
Filing date: 2021-02-05
Publication date: 2022-12-09
Anticipated expiration: 2041-02-05
Also published as: CN112812479A

Abstract

The invention discloses a biodegradable thermoplastic PVA/starch seed tape, which comprises the following raw materials: thermoplastic PVA, thermoplastic starch. The biodegradable thermoplastic PVA/starch seed tape with different degradation time can be prepared by the mixture ratio of the thermoplastic PVA and the thermoplastic starch. The prepared thermoplastic PVA/starch seed tape has good biodegradability and excellent seedling survival rate, is suitable for popularization in the field of agricultural films, and has wide development prospect.

Description

Biodegradable thermoplastic PVA/starch seed tape and preparation method thereof

Technical Field

The invention relates to the technical field of agricultural films, in particular to a biodegradable thermoplastic PVA/starch seed tape and a preparation method thereof.

Background

Traditional vegetables (like hot pepper, lettuce, turnip), sapling, flowers, the seeding mode adopts manual seeding or simple and easy seeder to broadcast more, and these two kinds of modes all are difficult to the quantity of accurate control seed, when extravagant a large amount of seeds, and the later stage needs a large amount of manual works "thinning out", pulls out unnecessary crop or grows seedlings earlier and transplants. Due to the double waste, the planting cost of farmers is high, the farmers are difficult to industrialize, the consistency of agricultural products is poor, the planting precision is low, and the product competitiveness is low.

At present, the problem of poor precision in the agricultural planting process can be well solved through a seed tape process. The seed tape process is to wrap seeds of crops in a degradable paper tape, to lay the paper tape in the ground by using a special seeder during seeding, to water, to melt the paper tape, and to break the seeds out.

At present, the production cost of the water solubility and the weaving strength of the paper tape is higher, the thermoplastic modified PVA/starch plastic applied by the invention can be subjected to film blowing/tape casting processing like a common plastic film, then the flow is cut into strips, and then weaving is carried out, so that the material cost and the production cost are lower than those of the traditional paper tape. And the addition proportion of the thermoplastic starch can be mainly adjusted according to the seedling growing period of crops so as to control the degradation time of the seed tape.

Disclosure of Invention

The invention provides a biodegradable thermoplastic PVA/starch seed tape, which comprises the following raw materials: thermoplastic PVA, thermoplastic starch.

As a preferable scheme, the weight ratio of the thermoplastic PVA to the thermoplastic starch is 2 to 9:2 to 9.

As a preferable scheme, the weight ratio of the thermoplastic PVA to the thermoplastic starch is 5-8: 2 to 5.

As a preferable scheme, the raw material of the thermoplastic PVA comprises the following parts by weight: 90 to 110 portions of PVA, 10 to 15 portions of glycerol, 0.01 to 0.05 portion of cross-linking agent, 2 to 3 portions of heat stabilizer and 0.2 to 0.6 portion of lubricant.

As a preferable scheme, the raw materials of the thermoplastic starch comprise the following parts by weight: 90-110 parts of starch, 30-35 parts of glycerol, 6-10 parts of a cross-linking agent, 2-3 parts of a heat stabilizer and 0.01-0.06 part of a lubricant.

As a preferable scheme, the PVA is at least one of PVA-0388, PVA-0588 and PVA-1788.

As a preferred embodiment, the PVA is PVA-0588 and PVA-1788; the weight ratio of PVA-0588 to PVA-1788 is 1-2: 3 to 4.

Preferably, the starch is at least one of tapioca flour, corn flour, wheat flour, barley flour and potato flour.

As a preferred scheme, the starch is cassava flour and corn flour; the weight ratio of the cassava powder to the corn powder is 1-2: 4 to 5.

The invention provides a preparation method of the biodegradable thermoplastic PVA/starch seed tape, which comprises the following steps: (1) Mixing thermoplastic PVA and thermoplastic starch, and adding the mixture into a high-speed stirrer for high-speed kneading; (2) Granulating the raw materials obtained in the step (1) by a double-screw extruder to prepare plastic particles; (3) Melting plastic particles, and blowing the plastic particles into a film by using a film blowing machine and a flow machine; (4) Slitting according to the requirement of crop seeds, and winding into seed belts.

Has the beneficial effects that:

1. the prepared seed tape has the characteristic of biodegradability, can be effectively and naturally degraded after seedling culture, saves transplanting work and fully saves labor cost.

2. The prepared seed tape can effectively ensure the normal growth of plant seedlings after being cultivated in soil, can be powdered and degraded in a short time after the seeds break membranes, and can optimize the structure and the nutrient content of the soil and further promote the growth of seedling; the whole using process is simple, environment-friendly and pollution-free, and the phenomenon that chemical residues damage soil quality to influence the seedling raising effect is avoided.

3. The seed tape prepared in the invention can adjust the compounding ratio of the thermoplastic starch and the thermoplastic PVA in the preparation process according to different seedling raising periods of crops so as to effectively control the degradation time of the seed tape, thereby more effectively matching the growth periods of different seedlings.

Detailed Description

The disclosure may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

As used herein, the term "consisting of 8230; preparation" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of 8230comprises" excludes any non-specified elements, steps or components. If used in a claim, this phrase shall render the claim closed except for the materials described except for those materials normally associated therewith. When the phrase "consisting of 8230is present in a clause of the claim body, rather than immediately after the subject matter, it defines only the elements described in that clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or range defined by a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. "optional" or "either" means that the subsequently described event or events may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, is intended to modify a quantity, such that the invention is not limited to the specific quantity, but includes portions that are literally received for modification without substantial change in the basic function to which the invention is related. Accordingly, the use of "about" to modify a numerical value means that the invention is not limited to the precise value. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. In the present description and claims, range limitations may be combined and/or interchanged, including all sub-ranges contained therein if not otherwise stated.

In addition, the indefinite articles "a" and "an" preceding an element or component of the invention are intended to have no limitation on the number (i.e., number of occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural unless the stated number clearly indicates that the singular form is intended.

In some preferred embodiments, the weight ratio of thermoplastic PVA to thermoplastic starch is from 2 to 9:2 to 9.

In some preferred embodiments, the weight ratio of thermoplastic PVA to thermoplastic starch is from 5 to 8:2 to 5.

In some preferred embodiments, the weight ratio of thermoplastic PVA to thermoplastic starch is from 6 to 7:3 to 4.

In some preferred embodiments, the starting material for the thermoplastic PVA comprises the following parts by weight: 90 to 110 portions of PVA, 10 to 15 portions of glycerol, 0.01 to 0.05 portion of cross-linking agent, 2 to 3 portions of heat stabilizer and 0.2 to 0.6 portion of lubricant.

In some preferred embodiments, the method of preparing the thermoplastic PVA comprises the steps of: (1) Adding glycerol into PVA, mixing with a heat stabilizer, a lubricant and a crosslinking agent, adding into a high-speed stirrer, and kneading at high speed; (2) And (2) putting the raw materials in the step (1) into a double-screw extruder for extrusion granulation, and obtaining the thermoplastic PVA after the granulation is finished.

In some preferred embodiments, the temperature of the high-speed stirrer is 110 to 120 ℃; the temperature of the double-screw extruder is 110-190 ℃.

In some preferred embodiments, the thermoplastic starch comprises the following raw materials in parts by weight: 90-110 parts of starch, 30-35 parts of glycerol, 6-10 parts of cross-linking agent, 2-3 parts of heat stabilizer and 0.01-0.06 part of lubricant.

In some preferred embodiments, the method for preparing the thermoplastic starch comprises the steps of: (1) Adding glycerol into starch, mixing with a heat stabilizer, a lubricant and a cross-linking agent, adding into a high-speed stirrer, and kneading at high speed; (2) And (2) putting the raw materials in the step (1) into a double-screw extruder for extrusion granulation, and obtaining the thermoplastic starch after granulation is completed.

In some preferred embodiments, the temperature of the high speed mixer is 110 to 120 ℃; the temperature of the double-screw extruder is 110-190 ℃.

In some preferred embodiments, the PVA is at least one of PVA-0388, PVA-0588, PVA-1788.

In some preferred embodiments, the PVA is PVA-0588 and PVA-1788; the weight ratio of PVA-0588 to PVA-1788 is 1-2: 3 to 4.

In some preferred embodiments, the starch is at least one of tapioca flour, corn flour, wheat flour, barley flour, potato flour.

In some preferred embodiments, the starch is tapioca flour and corn flour; the weight ratio of the cassava powder to the corn powder is 1-2: 4 to 5.

In some preferred embodiments, the crosslinking agent is at least one of calcium chloride, potassium chloride, sodium hexametaphosphate, citric acid, sodium borate, diisocyanate; the heat stabilizer is at least one of calcium stearate, sodium stearate, zinc stearate, magnesium hydroxide and rare earth stearate; the lubricant is at least one of stearic acid, polyamide wax and acetamide.

The invention provides a preparation method of the biodegradable thermoplastic PVA/starch seed tape, which comprises the following steps: (1) Mixing thermoplastic PVA and thermoplastic starch, and adding the mixture into a high-speed stirrer for high-speed kneading; (2) Granulating the raw materials obtained in the step (1) by a double-screw extruder to prepare plastic particles; (3) Melting plastic particles, and blowing or casting into a film by using a film blowing machine or a casting machine; (4) Slitting according to the requirement of crop seeds, and winding into seed belts.

In some preferred embodiments, the high speed kneading temperature is 95 to 120 ℃; the temperature of the double-screw extruder is 150-190 ℃; the melting temperature is 160-180 ℃; the blowing flow temperature is 140-180 ℃.

In some preferred embodiments, the PVA/starch thickness of the seed tape is 50 to 800 μm.

Examples

The technical solution of the present invention is described in detail by the following examples, but the scope of the present invention is not limited to all of the examples. The starting materials of the present invention are all commercially available unless otherwise specified.

Example 1

Embodiment 1 in a first aspect, there is provided a biodegradable thermoplastic PVA/starch seed tape, comprising the following raw materials in parts by weight: 70 parts of thermoplastic PVA and 30 parts of thermoplastic starch.

In the embodiment, the thermoplastic PVA is made by self, and the steps comprise the following steps: (1) To 100 parts of PVA (PVA-0588 and PVA-1788, in a weight ratio of 2: 3) was added 12 parts of glycerin, and mixed with 3 parts of calcium stearate, 0.6 part of stearic acid, and 0.01 part of potassium chloride, and added to a high-speed mixer to be kneaded at a high speed, the stirring temperature being 120 ℃; (2) And (2) putting the raw materials in the step (1) into a double-screw extruder for extrusion granulation, wherein the temperature of the double-screw extruder is 190 ℃, and obtaining the thermoplastic PVA after granulation.

In this example, the thermoplastic starch is self-made, and the steps include the following steps: (1) Adding 33 parts of glycerol into 100 parts of starch (tapioca powder and corn powder in a weight ratio of 1 to 4), mixing with 3 parts of calcium stearate, 0.04 part of acetamide and 10 parts of sodium hexametaphosphate, and adding into a high-speed stirrer for high-speed kneading, wherein the stirring temperature is 120 ℃; (2) And (2) putting the raw materials in the step (1) into a double-screw extruder for extrusion granulation, wherein the temperature of the double-screw extruder is 160 ℃, and obtaining the thermoplastic starch after granulation.

The embodiment also provides a preparation method of the biodegradable thermoplastic PVA/starch seed tape, which comprises the following steps: (1) Mixing 70 parts of thermoplastic PVA and 30 parts of thermoplastic starch, and adding the mixture into a high-speed stirrer for high-speed kneading, wherein the temperature of the high-speed stirrer is 110 ℃; (2) Granulating the raw materials obtained in the step (1) by a double-screw extruder, wherein the temperature of the double-screw extruder is 165 ℃, and preparing plastic particles; (3) Melting plastic particles at 170 ℃, and blowing the plastic particles into a film by using a film blowing machine and a flow machine, wherein the blowing flow temperature is 160 ℃; (4) Slitting according to the requirement of crop seeds, and winding into a seed tape.

In this embodiment: calcium stearate (CAS: 1592-23-0), stearic acid (CAS: 57-11-4), acetamide (CAS: 60-30-5), and sodium hexametaphosphate (CAS: 10124-56-8).

In this example, PVA-0588 and PVA-1788 are products of PVA-0588 and PVA-1788 sold by Kadu Utility Co.

Example 2

The embodiment of the present invention is different from embodiment 1 in that: 60 parts of thermoplastic PVA and 40 parts of thermoplastic starch.

Example 3

The embodiment of this embodiment is the same as embodiment 1, except that: the weight ratio of PVA-0588 to PVA-1788 is 1:4.

example 4

The embodiment of this embodiment is the same as embodiment 1, except that: the weight ratio of the cassava powder to the corn powder is 2:5.

comparative example 1

The embodiment of this comparative example is the same as example 1 except that: 90 parts of thermoplastic PVA and 10 parts of thermoplastic starch.

Comparative example 2

The embodiment of this comparative example is the same as example 1 except that: the weight ratio of PVA-0588 to PVA-1788 is 5:1.

comparative example 3

The embodiment of this comparative example is the same as example 1 except that: the weight ratio of the cassava flour to the corn flour is 5:1.

evaluation of Performance

1. Degradability in soil: the seed tapes obtained in examples and comparative examples were normally transplanted into soil along with the seedling seeds, the degradation rate of the seed tapes after 90 days was measured, 5 specimens were tested in each example and comparative example, and the average value of the measured values is shown in Table 1.

2. And (3) seedling survival rate: the seed belts prepared in the examples and the comparative examples, lawn seeds of the same variety and quantity, high-molecular water-absorbing particles and fertilizers are used together for seedling raising operation of the peppers, and the final survival rate of the pepper seedling raising field is recorded. Each example comparative example tested 5 samples and the average of the values measured is reported in table 1.

3. Seedling height: the seed tapes prepared in examples and comparative examples were normally cultivated with pepper seedlings (borea 6) for 40 days, and the seedling height of the pepper seedlings after 40 days was measured.

TABLE 1

Examples	Degradability in soil (%)	Height of plant seedling (cm)	Survival rate of seedling (%)
				Example 1	85.2	16.1	97.5
Example 2	84.3	15.3	96.5
				Example 3	83.2	15.5	96.6
Example 4	81.9	14.9	97.1
				Comparative example 1	68	11.2	80.5
Comparative example 2	58	10.9	84.7
				Comparative example 3	60	9.9	85.1

Through the embodiments 1 to 4 and the comparative examples 1 to 3, the PVA/starch seed tape prepared by the biodegradable thermoplastic PVA/starch seed tape and the preparation method thereof provided by the invention has good biodegradability and excellent seedling survival rate, is suitable for being popularized in the field of agricultural films, and has wide development prospect. Wherein example 1 achieves the best performance index with the best weight ratio of the raw materials, etc.

Finally, it should be understood that the above-described embodiments are merely preferred embodiments of the present invention, and not intended to limit the present invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A biodegradable thermoplastic PVA/starch seed tape, characterized in that: the raw materials comprise the following components: thermoplastic PVA, thermoplastic starch;

the weight ratio of the thermoplastic PVA to the thermoplastic starch is 5-8: 2 to 5;

the thermoplastic PVA comprises the following raw materials in parts by weight: 90 to 110 portions of PVA, 10 to 15 portions of glycerol, 0.01 to 0.05 portion of cross-linking agent, 2 to 3 portions of heat stabilizer and 0.2 to 0.6 portion of lubricant;

the thermoplastic starch comprises the following raw materials in parts by weight: 90-110 parts of starch, 30-35 parts of glycerol, 6-10 parts of cross-linking agent, 2-3 parts of heat stabilizer and 0.01-0.06 part of lubricant;

the PVA is PVA-0588 and PVA-1788; the weight ratio of PVA-0588 to PVA-1788 is 1-2: 3 to 4;

the starch is cassava flour and corn flour; the weight ratio of the cassava powder to the corn powder is 1-2: 4 to 5.

2. A method of preparing a biodegradable thermoplastic PVA/starch seed tape according to claim 1, characterized in that: the method comprises the following steps: (1) Mixing thermoplastic PVA and thermoplastic starch, and adding the mixture into a high-speed stirrer for high-speed kneading; (2) Granulating the raw materials obtained in the step (1) by a double-screw extruder to prepare plastic particles; (3) Melting plastic particles, and blowing or casting the plastic particles into a film by using a film blowing machine or a casting machine; (4) Slitting according to the requirement of crop seeds, and winding into a seed tape.