CN116575267A - Plastic film paper for greenhouse and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of mulch paper, and discloses mulch paper for a greenhouse and a preparation method thereof, wherein the mulch paper comprises the following steps: pulping the wheat straw biomechanical pulp with a beating degree of 35-40 DEG SR to obtain pulp; fully mixing the slurry with a papermaking auxiliary agent, and papermaking to obtain mulch film base paper; uniformly coating gelatinized cationic starch or gelatinized soybean oil modified starch on one side or the front and the back of the mulch film base paper, and drying; and then uniformly coating polyurethane or acrylic resin coating on one side or the front side and the back side, and drying to obtain the polyurethane or acrylic resin coating. The mulching film takes biomechanical pulp as a main raw material, realizes high physical and mechanical properties and high hydrophobic moisture resistance of mulching film paper by a method of adding in pulp and coating on the surface, can replace black plastic mulching film, and solves the problems of environmental pollution and the like caused by plastic mulching film.

Description

A kind of mulch paper for greenhouse and preparation method thereof

technical field

The invention belongs to the technical field of mulch paper, and in particular relates to a mulch paper for greenhouses and a preparation method thereof.

Background technique

The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

As a large agricultural country, my country has become the world's largest producer and user of agricultural film. At present, most plastic films are mainly made of petroleum-based plastics such as polyvinyl chloride (PVC) and polyethylene (PE), which are difficult to completely degrade when left in the soil and damage the ecology. Black mulch is a kind of plastic mulch often laid in crop greenhouses, which can play a role in heat preservation, moisturizing, and weeding. It is often used to improve the growth environment of crops, increase the utilization rate of fertilizers, and avoid the influence of weeds on the quality of crops.

Due to the environmental pollution caused by plastic mulch, degradable mulch has gradually become the focus of research, and paper-based mulch has certain advantages. Paper base film is made of plant fiber, mixed according to different pulp or different proportions, and obtained through papermaking technology. It has certain dry strength and light-shielding properties, but the light-shielding property of paper base film is not as good as that of black film, so it inhibits weeds Growth performance is not as good as black mulch.

More importantly, the traditional plastic-based black mulch has good moisture retention properties, which can effectively prevent the evaporation of soil moisture. However, the water vapor barrier performance of the paper base film is poor, and it is difficult to meet the moisture retention performance requirements of the black plastic film. In addition, current paper-based membranes still do not have the high dry and high wet strengths required for use in greenhouses. Moreover, the preparation cost of the current paper-based film is relatively high, which hinders its popularization and application.

Therefore, although the current paper base film has good biodegradability, it is still difficult to replace the black plastic film.

Contents of the invention

Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a kind of mulch paper for greenhouses and its preparation method. The mulch uses biomechanical pulp as the main raw material, and realizes the mulching of the mulch paper through the method of adding in the pulp and coating the surface. With high physical and mechanical properties and high hydrophobicity and moisture resistance, it can replace black plastic mulch and solve environmental pollution caused by plastic mulch.

In order to achieve the above object, the present invention is achieved through the following technical solutions:

In the first aspect, the present invention provides a method for preparing mulch paper for greenhouses, comprising the following steps: dissolving the biomechanical pulp of wheat straw straw and performing beating treatment with a beating degree of 35-40°SR to obtain a slurry;

After fully mixing the slurry and papermaking additives, papermaking is carried out to obtain mulch base paper;

Uniformly coat gelatinized cationic starch or gelatinized soybean oil-modified starch on one side or front and back of mulch base paper, and dry; the mass percentage of cationic starch aqueous solution is 3-10% during gelatinization; the content of starch in soybean oil-modified starch The mass percentage is 2.5-10%;

Then apply polyurethane or acrylic resin coating evenly on one side or front and back, and get it after drying.

In some embodiments, the papermaking aids include cationic polyacrylamide (CPAM) or cationic starch (CAS) or chitosan at 0.5%-3% of dry pulp mass, and 1.5%-3% of dry pulp mass Polyamide polyamine epichlorohydrin, alkyl ketene dimer (AKD) or aluminum sulfate at 0.5%-2% dry pulp mass and cat/anionic polyacrylamide at 0.1%-0.3% dry pulp mass Or cationic/anionic starch.

Biomechanical pulp is firstly pretreated with biological enzymes and then mechanically refined. The biological enzyme is a compound enzyme formed by compounding pectinase, lipase and xylanase in a certain ratio. Using biomechanical pulp, shifting from traditional high temperature and high alkali to low temperature, low alkali or alkali-free bio-green pulping technology, combining modern biotechnology with mechanical pulping of agricultural straw, and replacing traditional chemicals with biological enzyme preparations, both It can solve the shortage of papermaking raw materials caused by the sharp drop in waste paper imports, and can also achieve zero discharge of waste water.

By adding polyamide polyamine epichlorohydrin (PAE) wet strength agent in the pulp, the paper has obvious humidification strength and surface water resistance, and the specific dosage is discussed. When the amount reaches 2.5%. , reach optimal effect (see embodiment 4 for details).

In order to achieve a water vapor transmission rate lower than 800g/m ² ·24h, the inventors discussed the internal sizing process and surface coating process. The first layer of the surface coating process is gelatinized cationic starch layer or modified starch coating, only the gelatinized cationic starch layer or modified starch layer can reduce the water vapor transmission rate from 2895g/m ² ·24h of base paper to 2100g/m ² ·24h or less; the second layer is a hydrophobic moisture-resistant coating, which is a coating of polyurethane or acrylic resin. Under the premise of reducing the coating amount as much as possible, the preferred two hydrophobic moisture-resistant coatings The water vapor transmission rate of the mulch paper is below 800g/m ² ·24h.

The hydrophobic moisture barrier coating can also enhance the mechanical properties and hydrophobic properties of the paper base film.

The degradable parts of the two natural-color mulch papers coated with acrylic resin and polyurethane account for more than 95% of the total mass, and can basically achieve full biodegradation after use. Degradation experiments showed that the two mulch papers still maintained a good original appearance after 80 days in the soil.

In order to reduce the visible light transmittance, a visible light transmittance effect lower than 5% is achieved. Wheat straw biomechanical pulp is used as raw material, which has the advantages of environmental protection, low cost and opacity, and the obtained mulch base paper has a low visible light transmittance of 3.6%. The light transmittance is further reduced, so that the visible light transmittance of the mulch paper is always kept below 5%.

After testing, it is found that the gelatinized cationic starch layer or modified starch layer coated in the present invention can not only improve the water vapor barrier performance and visible light barrier performance of the paper base film, but also improve the mechanical strength of the paper base film and improve the performance of the paper base film. Smoothness, reduce its water absorption. In addition, the gelatinized cationic starch layer or modified starch layer also has a good pore-filling effect, which can reduce the coating amount of hydrophobic and moisture-resistant coatings such as polyurethane and acrylic resin, and can effectively save the preparation cost of mulch paper and facilitate the production of mulch paper. Promote apps.

When 0.5-3% dry strength agent (cationic polyacrylamide (CPAM) or cationic starch (CAS) or chitosan) is added to biomechanical pulp, the dry strength of base paper can be increased by up to 30% about.

When 1.5-3% wet strength agent (polyamide polyamine epichlorohydrin) is added to the biomechanical pulp, the wet strength of the base paper can be increased by about 369%.

When 0.5-2% of sizing agent (alkyl ketene dimer (AKD) or aluminum sulfate) is added to biomechanical pulp, the sizing agent works together with dry strength agent and wet strength agent , It can increase the dry strength of base paper by about 46% and its wet strength by about 400%.

When 0.1-0.3% retention aid (cationic/anionic polyacrylamide or cationic/anionic starch) is added to biomechanical pulp, it can effectively improve the retention rate of pulp when it is online, and it is effective for fine fibers Good retention effect, obvious pulp saving. Moreover, because the retention rate of fine fibers is good, the light transmittance of the prepared paper base film can be effectively reduced to better inhibit the growth of weeds. When the amount of retention aid added is too much, it will cause the appearance of deposits.

In some embodiments, it further includes the step of adding 0-40% by mass waste corrugated pulp or 0-40% wheat straw pulp to the biomechanical pulp of wheat straw.

Adding waste corrugated pulp or wheat straw pulp to wheat straw biomechanical pulp can reduce costs. It has been found through experiments that when 0-40% by mass of waste corrugated pulp or wheat straw pulp is added to wheat straw biomechanical pulp, the prepared paper The dry and wet strength of the base film will not be significantly reduced, and the dark waste corrugated pulp is more conducive to reducing the visible light transmittance of the film paper.

In some embodiments, the papermaking aids include cationic polyacrylamide or cationic starch or chitosan at 0.5%-2% dry pulp mass, polyamide polyamine ring at 2%-3% dry pulp mass Oxychloropropane, 0.5%-1% of dry pulp mass of alkyl ketene dimer or aluminum sulfate, and 0.1%-0.2% of dry pulp mass of cationic/anionic polyacrylamide or cationic/anionic starch.

Preferably, the papermaking auxiliary agent includes cationic polyacrylamide of 1%-2% of dry pulp mass, polyamide polyamine epichlorohydrin of 2%-3% of dry pulp mass, 0.5% of dry pulp mass - 1% of alkyl ketene dimer.

In some embodiments, the preparation method of the gelatinized cationic starch is as follows: after adjusting the aqueous solution of the cationic starch to be alkaline, heating to 40-50° C., and stirring for 20-40 minutes, the product is obtained.

Preferably, the mass percentage of the cationic starch aqueous solution is 3-10%, preferably 7%.

Preferably, in the cationic starch aqueous solution, the mass percentage of sodium hydroxide is 8%-15%.

In some embodiments, the preparation method of the gelatinized soybean oil-modified starch is as follows: adding soybean oil and sodium carbonate to the dimethyl sulfoxide solution of the starch to obtain a mixed solution, heating to 110-150° C., and heating for 1 -3h, carry out hydrophobic modification on starch to obtain modified starch.

Soybean oil substitutes hydroxyl groups to modify starch by esterification, which can effectively improve the hydrophobicity of starch. Sodium carbonate is used as a catalyst to promote the modification reaction.

Preferably, in the mixed liquid, the mass percentage of starch is 2.5-10%, the mass percentage of soybean oil is 8-12%, and the mass percentage of sodium carbonate is 13-17%.

Preferably, the modified starch undergoes the same gelatinization process as the cationic starch.

In some embodiments, the coating method of gelatinized cationic starch or gelatinized soybean oil-modified starch is as follows: use a 10 μm linear coating rod to coat the surface of the mulch base paper, and then dry it.

Preferably, the coating amount of the gelatinized cationic starch or the gelatinized soybean oil-modified starch is 1.5-2 g/m ² on one side, and 3-4 g/m ² on both sides.

In some embodiments, the coating method of the hydrophobic and moisture-resistant coating is as follows: a 4 μm linear coating rod is used to coat the surface of the gelatinized cationic starch or gelatinized modified starch coating, and it is obtained after drying.

Preferably, the coating amount of the polyurethane on one side is 1.5-2 g/m ² , and the coating amount on both sides is 3-4 g/m ² .

Preferably, the coating amount of the acrylic resin on one side is 2.5-3 g/m ² , and the coating amount on both sides is 5-6 g/m ² .

Compared with the dipping method and the spraying method, the coating method can accurately control the amount of paint, and the formed coating has good uniformity. The 4μm linear coating rod can minimize the coating weight.

In some embodiments, the basis weight of the mulch base paper is 60-70 g/m ² .

Both polyurethane and acrylic coatings are dried at 105-110°C.

In the second aspect, the present invention provides a mulch paper for greenhouses, which is prepared by the preparation method.

The beneficial effects obtained by one or more embodiments of the present invention are as follows:

1) The water resistance of the mulch paper is Cobb ₁₂₀ ≤ 20g/m ² , which has certain hydrophobic properties, which is beneficial to prolong the service life of the mulch paper in a humid environment.

2) The water vapor transmission rate is less than or equal to 800g/m ² ·24h, which has strong barrier performance to water vapor and can reduce soil water loss.

3) Physical strength index: tear index ≥ 2.5mN·m ² /g, burst index ≥ 2kPa.m ² /g, wet tensile index ≥ 25% dry tensile index, so that the film paper will not be damaged within the coverage period fester.

4) The light transmittance is less than or equal to 5%, which can favorably inhibit the growth and development of weeds and achieve the purpose of inhibiting the growth of weeds.

5) The relative biodegradation rate is ≥90%. After use, it can be completely or mostly degraded into organic matter and enter the land, which is conducive to improving the soil structure.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

Figure 1 is a flow chart of the preparation of natural-color degradable mulch paper for greenhouses.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. 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.

The present invention will be described in further detail below in conjunction with specific examples. It should be pointed out that the specific examples are to explain rather than limit the present invention.

Example 1

Manufacture of mulch base paper: Take about 500g of dry weight biomechanical pulp and beat it with a tile beater to obtain biomechanical pulp with a beating degree of about 20°SR, 30°SR, and 40°SR respectively, and use the pulp after beating Filter out most of the water in the bag, put it in a low-temperature refrigerator at 5°C for 24 hours to balance the water, and measure the solid content.

Get 1.88g of absolute dry pulp and absolute dry pulp weight percentage 0.5% CPAM dry strength agent, 2% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid, blend in the deflagging machine, 10000 Turn down to deflate to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 5wt% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch. Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on the front of the mulch base paper, and dry at 80°C for 10 minutes. Take it out, continue to coat polyurethane on the front starch layer with a 4 μm linear coating rod, and dry it at 110°C for 10 minutes to obtain it.

The properties of the mulch paper prepared with different beating degrees are shown in Table 1.

Table 1 Properties of mulch paper prepared with different degrees of beating

Example 2

Manufacture of mulch base paper: take about 500g of dry-weight biomechanical pulp and beat it with a Wall-E beater to obtain biomechanical pulp with a beating degree of about 40°SR. After beating, use a pulp bag to filter out most of the water. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

Get 1.88g, 2.19g of absolute dry pulp and absolute dry pulp weight percentage 0.5% CPAM dry strength agent, 2% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid of papermaking aids, in the deflaker Mix and decompose at 10,000 rpm to completely disperse the fibers. After flaking, the slurry is sent to a paper machine to obtain mulch base papers with a weight of 60g/ ^m2 and 70g/ ^m2 .

Coating experiment of mulch base paper: first prepare 5wt% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch.

Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on the front of the mulch base paper, and dry at 80°C for 10 minutes. Take it out, continue to coat polyurethane on the front starch layer with a 4 μm linear coating rod, and dry it at 110°C for 10 minutes to obtain it.

The properties of prepared different quantitative mulch papers are shown in Table 2.

Table 2 Properties of mulch paper quantitatively prepared by different papermaking

Example 3

Manufacture of mulch base paper: take about 500g of dry weight biomechanical pulp, and beat it with a tile beater. The beating time is about 20 minutes, and the beating degree is about 40°SR. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

Take 1.88g dry pulp and dry pulp weight percentage 0.5%, 1%, 1.5%, 2% CPAM dry strength agent, 2.5% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid agent, blended in a deflagging machine, and deflagrated at 10,000 rpm to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 5% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch.

Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on both sides of the mulch base paper, and dry at 80°C for 10 minutes. Take it out, use a 4μm linear coating rod to continue to coat polyurethane on the front and back starch layers, and dry at 110°C for 10 minutes to obtain it.

The properties of the mulch paper prepared with different dry strength agent contents are shown in Table 3.

Table 3 Properties of film paper prepared with different dry strength agent contents

Example 4

Manufacture of mulch base paper: take about 500g of dry weight biomechanical pulp, and beat it with a tile beater. The beating time is about 20 minutes, and the beating degree is about 40°SR. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

Get 1.88g dry pulp and dry pulp weight percentage 1% CPAM dry strength agent, 2%, 2.5%, 3% PAE wet strength agent, 0.5% AKD sizing agent and the papermaking auxiliary agent of 0.1% retention aid, in Blending in the deflaking machine, deflaking at 10,000 rpm to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 5wt% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch.

Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on both sides of the mulch base paper, and dry at 80°C for 10 minutes. Take it out, use a 4μm linear coating rod to continue to coat polyurethane on the front and back starch layers, and dry at 110°C for 10 minutes to obtain it.

The properties of mulch paper prepared with different wet strength agent contents are shown in Table 4.

Table 4 Properties of film paper prepared with different wet strength agent contents

Example 5

Manufacture of mulch base paper: take about 500g of dry weight biomechanical pulp, and beat it with a tile beater. The beating time is about 20 minutes, and the beating degree is about 40°SR. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

1.88g absolute dry pulp and papermaking aids of absolute dry pulp weight percentage 1% CPAM dry strength agent, 2.5% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid are blended in the deflagging machine, 10000 Turn down to deflate to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 1%, 5%, 7% cationic starch aqueous solution, and then add sodium hydroxide with 10% starch mass. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch.

Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on the front of the mulch base paper, and dry at 80°C for 10 minutes. Take it out, continue to coat the acrylic resin on the front starch layer with a 4 μm linear coating rod, and dry it at 110°C for 10 minutes to obtain it.

The properties of the film paper prepared with different cationic starch concentrations are shown in Table 5.

Table 5 Properties of film paper prepared with different cationic starch concentrations

It can be seen from Table 4 that the concentration of gelatinized cationic starch is different, resulting in differences in the actual coating amount of starch; when the concentration of gelatinized cationic starch increases, its effect on fiber hole filling is improved, so that the coating amount of acrylic resin is reduced. Make the relevant properties of the mulch paper meet the requirements.

Example 6

Manufacture of mulch base paper: take about 500g of dry weight biomechanical pulp, and beat it with a tile beater. The beating time is about 20 minutes, and the beating degree is about 40°SR. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

1.88g absolute dry pulp and papermaking aids of absolute dry pulp weight percentage 1% CPAM dry strength agent, 2.5% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid are blended in the deflagging machine, 10000 Turn down to deflate to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 7% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch. Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on both sides of the mulch base paper, and dry at 80°C for 10 minutes. Take it out, continue to coat polycaprolactone (PCL), polyvinylidene chloride (PVDC), and modified starch on the front and back starch layers with a 4 μm linear coating rod, and dry at 30°C for 10 minutes.

The properties of the mulch paper prepared with different hydrophobic and moisture-resistant coatings are shown in Table 6.

Table 6 Properties of mulch paper prepared by different hydrophobic and moisture-resistant coatings

During the experiment, the coating effects of PCL and PVDC were compared. Although the hydrophobic properties and water vapor barrier properties are excellent, the two coatings are relatively difficult to coat, and the coating amount is difficult to reduce, resulting in high coating costs.

Example 7

Manufacture of mulch base paper: take about 500g of dry weight biomechanical pulp, and beat it with a tile beater. The beating time is about 20 minutes, and the beating degree is about 40°SR. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

1.88g absolute dry pulp and papermaking aids of absolute dry pulp weight percentage 1% CPAM dry strength agent, 2.5% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid are blended in the deflagging machine, 10000 Turn down to deflate to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 7% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch. Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on both sides of the mulch base paper, and dry at 80°C for 10 minutes. Take it out, use a 4 μm linear coating rod to continue coating polyurethane on the front and back starch layers, and dry at 110°C for 10 minutes to obtain the mulch paper. The properties of the prepared mulch paper are shown in Table 7.

Table 7 Properties of mulch paper

The water resistance Cobb ₁₂₀ of the mulch paper is 8.6g/m ² , showing excellent hydrophobic properties, which is conducive to the sliding of water droplets on the surface of the mulch paper and prolonging the service life of the mulch paper.

The water vapor transmission rate of the mulch paper is 683g/m ² ·24h, which is 424% higher than that of the mulch base paper. Through the coating process, the mulch paper is endowed with good water vapor barrier properties, which can effectively prevent the water loss of soil and crops, and achieve the effect of increasing production and efficiency.

The physical strength index of the film paper: the tear index is 8.3mN·m ² /g, the burst index is 2.48kPa.m ² /g, the dry tensile index is 35.6N·m/g, and the wet tensile index is 26.7N m/g. The four test results all meet the requirements of laying in the greenhouse, and the wet tensile index has reached 75% of the dry tensile index, which is 556% higher than that of the base paper, indicating that even in a high humidity environment in the greenhouse, biomechanical Slurry film paper can also be used for a long time.

The light transmittance of the mulch paper is 3.9%, which can effectively inhibit the growth and development of weeds, so as to achieve the purpose of inhibiting the growth of weeds in the area covered by the mulch paper.

Example 8

Manufacture of mulch base paper: take about 500g of dry weight biomechanical pulp, and beat it with a tile beater. The beating time is about 20 minutes, and the beating degree is about 40°SR. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

1.88g absolute dry pulp and papermaking aids of absolute dry pulp weight percentage 1% CPAM dry strength agent, 2.5% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid are blended in the deflagging machine, 10000 Turn down to deflate to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 7% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch.

Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on both sides of the mulch base paper, and dry at 80°C for 10 minutes.

Take it out, use a 4μm linear coating rod to continue coating acrylic resin on the front and back starch layers, and dry at 110°C for 10 minutes to obtain it.

The properties of the prepared mulch paper are shown in Table 8.

Table 8 Performance of mulch paper

The water resistance Cobb ₁₂₀ of the mulch paper is 18.7g/m ² , which has a certain hydrophobicity, which is beneficial to prolong the service life of the mulch paper in a humid environment.

The water vapor transmission rate of the mulch paper is 734g/m ² ·24h, which is 394% higher than that of the mulch base paper. By coating acrylic resin, the water vapor barrier performance of mulch paper is still lower than 800g/m ² ·24h, and the cost is lower than that of polyurethane.

The physical strength index of the film paper: the tear index is 7.3mN·m ² /g, the burst index is 2.27kPa.m ² /g, the dry tensile index is 44.7N·m/g, and the wet tensile index is 20.7N m/g. The four test results meet the requirements for paving in greenhouses, and the wet tensile index reaches 46% of the dry tensile index, which is 431% higher than that of base paper. Compared to Example 1, Example 2 exhibited a higher dry tensile index.

The light transmittance of the mulch paper is 4.5%, which can still be beneficial to inhibit the growth and development of weeds, and achieve the purpose of inhibiting the growth of weeds.

Comparative example 1

Manufacture of mulch base paper: take about 500g of dry weight biomechanical pulp, and beat it with a tile beater. The beating time is about 20 minutes, and the beating degree is about 40°SR. Put it in a 5°C low-temperature refrigerator for 24 hours to balance the moisture, and measure the solid content.

1.88g absolute dry pulp and papermaking aids of absolute dry pulp weight percentage 1% CPAM dry strength agent, 2.5% PAE wet strength agent, 0.5% AKD sizing agent and 0.1% retention aid are blended in the deflagging machine, 10000 Turn down to deflate to completely disperse the fibers. After thawing, the slurry is sent to the paper machine to obtain 60g/ ^m2 mulch base paper.

Coating experiment of mulch base paper: first prepare 7% cationic starch aqueous solution, and then add 10% starch mass of sodium hydroxide. At 40°C, mechanically stir at 10,000 rpm for 30 minutes to obtain gelatinized cationic starch. Fix the mulch base paper, use a 10 μm linear coating rod to evenly coat the gelatinized cationic starch on both sides of the mulch base paper, and dry at 80°C for 10 minutes.

The properties of the prepared film paper are shown in Table 9.

Table 9 Properties of mulch paper

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A preparation method of mulching film paper for greenhouse is characterized by comprising the following steps: the method comprises the following steps:

fluffing the wheat straw biomechanical pulp, and pulping to obtain pulp with a beating degree of 35-40 DEG SR;

fully mixing the slurry with a papermaking auxiliary agent, and papermaking to obtain mulch film base paper;

uniformly coating gelatinized cationic starch or gelatinized soybean oil modified starch on one side or the front and the back of the mulch film base paper, and drying; the mass percentage of the cationic starch aqueous solution during gelatinization is 3-10%; the mass percentage of starch in the soybean oil modified starch is 2.5-10%;

and then uniformly coating polyurethane or acrylic resin coating on one side or the front side and the back side, and drying to obtain the polyurethane or acrylic resin coating.

2. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the method also comprises the step of adding 0-40% of waste corrugated paper pulp or 0-40% of wheat straw pulp into the wheat straw biomechanical pulp, wherein the adding proportion of the waste corrugated paper pulp or the wheat straw pulp is not 0.

3. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the papermaking auxiliary agent comprises 0.5-3% of absolute dry pulp by mass of cationic polyacrylamide or cationic starch or chitosan, 1.5-3% of absolute dry pulp by mass of polyamide polyamine epichlorohydrin, 0.5-2% of absolute dry pulp by mass of alkyl ketene dimer or aluminum sulfate and 0.1-0.3% of absolute dry pulp by mass of cationic/anionic polyacrylamide or cationic/anionic starch;

preferably, the papermaking auxiliary agent comprises 1-2% of absolute dry pulp by mass of cationic polyacrylamide or cationic starch or chitosan, 2-3% of absolute dry pulp by mass of polyamide polyamine epichlorohydrin, 0.5-1% of absolute dry pulp by mass of alkyl ketene dimer or aluminum sulfate and 0.1-0.2% of absolute dry pulp by mass of cationic/anionic polyacrylamide or cationic/anionic starch;

preferably, the papermaking auxiliary agent comprises 1-2% of cationic polyacrylamide, 2-3% of polyamide polyamine epichlorohydrin and 0.5-1% of alkyl ketene dimer.

4. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the preparation method of the gelatinized cationic starch comprises the following steps: adjusting the aqueous solution of cationic starch to alkaline, heating to 40-50deg.C, and stirring for 20-40min to obtain the final product;

preferably, the mass percentage of the cationic starch aqueous solution is 3-10%;

preferably, in the cationic starch aqueous solution, the mass percentage of the sodium hydroxide is 8-15%.

5. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the preparation method of the soybean oil modified starch comprises the following steps: adding soybean oil and sodium carbonate into dimethyl sulfoxide solution of starch to obtain mixed solution, heating to 110-150deg.C for 1-3h, and hydrophobically modifying starch;

preferably, in the mixed solution, the mass percentage of the starch is 2.5-10%; the mass percentage of the soybean oil is 8-12%; the mass percentage of the sodium carbonate is 13-17%.

6. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the coating mode of the gelatinized cationic starch or the gelatinized soybean oil modified starch is as follows: coating the surface of the mulching film base paper by using a 10 mu m linear coating rod, and drying;

preferably, the one-sided coating amount of the gelatinized cationic starch or the gelatinized soybean oil modified starch is 1.5-2g/m ² The coating weight of the two sides is 3-4g/m ² 。

7. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the coating mode of the polyurethane or acrylic resin coating is as follows: and (3) coating the surface of the gelatinized cationic starch or the gelatinized modified starch coating by using a 4 mu m linear coating rod, and drying to obtain the modified starch.

8. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the single-sided coating weight of the polyurethane is 1.5-2g/m ² The coating weight of the two sides is 3-4g/m ² ；

Preferably, the acrylic resin has a single-sided coating amount of 2.5 to 3g/m ² The coating weight of the double-sided coating is 5-6g/m ² 。

9. The method for producing mulching film paper for greenhouse according to claim 1, characterized in that: the ration of the base paper of the mulch film is 60-70g/m ² 。

10. The utility model provides a plastic film paper for big-arch shelter which characterized in that: prepared by the preparation method of any one of claims 1 to 9.