CN109082947B

CN109082947B - Preparation method of colored pulp molded product

Info

Publication number: CN109082947B
Application number: CN201810786022.3A
Authority: CN
Inventors: 王文强; 张利丽; 江海亮; 许涛; 陈俊忠; 左华伟; 杨小龙; 李炳霈
Original assignee: Yongfa Henan Moulding Technology Development Co ltd
Current assignee: Yongfa Henan Moulding Technology Development Co ltd
Priority date: 2018-07-17
Filing date: 2018-07-17
Publication date: 2020-08-11
Anticipated expiration: 2038-07-17
Also published as: CN109082947A

Abstract

The invention discloses a preparation method of a colored pulp molding product, which comprises the steps of preparing bamboo fiber pulp, adding a corresponding weight part of an adhesive waterproofing agent and an anionic emulsifier, and stirring to form a pulp suspension; diluting and adding direct suntan or direct suntan orange into the prepared pulp suspension; finally, the pulp suspension is sent to a molding machine for dehydration and hot-press molding. Meanwhile, the invention also discloses a colored paper pulp molded product prepared by the method, and the molded product is uniformly colored and is easy to degrade in natural environment, thus being an environment-friendly paper pulp molded product.

Description

Preparation method of colored pulp molded product

Technical Field

The invention relates to the field of paper pulp molding, in particular to a preparation method of a colored paper pulp molded product.

Background

In recent years, as the demand of products in the manufacturing industry, particularly outer packaging manufactured products, is increasing, the immaturity of the manufacturing process also brings corresponding environmental problems, and people have stronger environmental protection consciousness, so that technicians have intensive research on manufacturing renewable resources.

The traditional pulp molding products are mostly used for manufacturing paper tableware, fruit egg trays and lining buffer materials of product packaging to replace the use of plastics. For the outer package of products with higher appearance requirements, the traditional materials such as plastics, iron boxes and the like are still adopted, so that the products are not environment-friendly enough and have higher cost. In the field of papermaking, the surface performance of paper is improved through a paper coating technology, and the added value and the application range of the paper are improved. Due to the particularity of the pulp molded product, the surface is not flat, the surface of the traditional pulp molded product is rough, the appearance is poorer than that of other types of packages, the appearance is related to the fiber characteristics of the pulp, and the rough, water-absorbing and inflammable properties of the fiber surface cause the prepared product to have certain limitations in the aspects.

The bamboo fiber as a fast-growing and high-yield plant has the advantages of high survival rate of planting, short growth period, stronger wear resistance and hygroscopicity, stronger strength than cotton fiber and viscose fiber and wide application prospect, but has super-strong instant hygroscopicity compared with other raw materials or renewable resources, and needs higher requirements on waterproofness to a certain extent. On the other hand, in order to improve the water resistance and the oil resistance of the existing paper pulp molding product, a corresponding waterproof agent and an oil-proof agent are added, and in the natural degradation process of the prepared product, because the waterproof agent is characterized by weak cationic property, the waterproof agent is added into the paper pulp and is attached to the surface of the fiber due to electrostatic adsorption to form a film on the surface of the fiber, so that the connection between the fiber and the fiber is tighter, the breakage of a cellulose macromolecular chain is inhibited to a certain extent, the tensile strength of the paper pulp molding product is improved along with the imposition of the dosage of the waterproof agent, the quality of the paper pulp molding product is slowly reduced in a natural environment, and the weight loss rate is; meanwhile, grooves and cracks exist on the surface of the bamboo fiber hollow cavity, branches and knots are transversely formed on the surface of the bamboo fiber hollow cavity, the bamboo fiber hollow cavity is light in weight, the bamboo fiber hollow cavity has excellent dyeing property, but the dyeing fastness of direct dyes is poor, a fiber crystallization area is increased in the dyeing process, the structure becomes compact, the dyeing rate is reduced, the dyeing is not uniform enough, and the problems are caused to later natural degradation.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects in the prior art and provide a paper pulp molded product which is uniformly colored, environment-friendly and easy to degrade and a preparation method thereof.

The invention provides a preparation method of a colored pulp molded product, which comprises the following steps:

(1) preparing bamboo fiber slurry, namely cooking raw bamboos in boiling water for 1-2 hours, then performing disintegration and grinding to obtain bamboo fibers, selecting bamboo fibers of 200-400 meshes, adding water of which the weight is 2-3 times that of the bamboo fibers, and stirring to obtain the slurry;

(2) the preparation of the bamboo fiber mixture comprises the following steps of selecting the following raw materials in parts by weight and stirring to form a paper pulp suspension:

(3) preparation of colored pulp comprising:

diluting direct suntan or direct suntan orange to 0.5 mass percent by soft water at 60-80 ℃, and adding the diluted solution into the prepared bamboo fiber mixture;

(4) and (3) molding pulp, and feeding the pulp suspension into a molding machine for dewatering and hot-pressing molding.

Optionally, in the step (3), after the color pigment is added, 0.1 to 0.2 part by weight of sodium chloride with the concentration of 60g/L and/or 0.1 to 0.2 part by weight of sodium hydroxide with the concentration of 20g/L are added every 8 to 10 minutes, and the steps are repeated for at least 3 times.

Alternatively, in step (3), three dyeing stages are sequentially divided, including:

dyeing for 15min at the dyeing temperature of 50 ℃;

dyeing for 5min at the dyeing temperature of 60 ℃;

at a dyeing temperature of 45 ℃, the dyeing is carried out for 5 min.

Optionally, 0.1-0.2 part by weight of soda ash of 25g/L is added at the same time of the first addition of the sodium chloride solution.

Optionally, after the pulp is molded, the method further comprises the step of spraying atomized UV gloss oil on the surface of the pulp.

Optionally, the water repellent agent is a cationic neutral sizing agent.

Optionally, the anionic emulsifier is dimethylolpropionic acid and/or dimethylolbutyric acid.

Optionally, the adhesive is prepared by mixing water, carboxymethyl cellulose and starch in a ratio of 1: 1-2: 1-2 parts by weight.

Optionally, in the steps (1) and (2), the stirring speed is 900 rpm-1200 rpm, and the stirring time is 15 min-20 min.

Optionally, in the step (3), the paper pulp is conveyed to a vacuum suction molding machine, dehydrated, extruded and dehydrated to form a blank, and then the blank is dried by hot pressing to obtain a paper pulp molding; the dehydration time is 30-60 seconds, and the wet blank is dried at 100 ℃ for 40-60 minutes.

The invention also provides a paper pulp molding product prepared by using the preparation method of the colored paper pulp molding product.

The technical scheme of the invention has the following advantages:

according to the preparation method of the paper pulp molding product, raw bamboo is selected as a molding product to prepare raw material fiber, the paper pulp molding is a high-energy-consumption industry, the bamboo grows rapidly and has strong regeneration capacity and superiority as a fiber raw material, and in addition, the molding product produced by the bamboo has natural bamboo fragrance as a high-grade product package and an inner lining because of the bamboo oil component contained in the molding product; the waste can be recycled.

Bamboo has strong hygroscopicity, wear resistance and easy dyeability due to natural properties of bamboo, and as a product, particularly a package of a high-grade product or an electronic product, the bamboo needs to have excellent waterproofness so as to prevent a shell from deforming or mildewing due to water absorption, so that quantitative or even more waterproofing agents need to be added in the process of making paper pulp so as to ensure good waterproof and damp-proof properties of the product. Because the waterproof agent is weak cationic, is attached to the surface of the fiber by electrostatic adsorption, and forms a film on the surface of the fiber, the connection between the fiber and the fiber is tighter, the breakage of cellulose macromolecular chains is inhibited to a certain extent, the tensile strength is improved, and the degradation difficulty of products is increased, when the bamboo fiber mixture is prepared, 0.5-0.8 wt% of anionic emulsifier is added, such as dimethylolpropionic acid or dimethylolbutyric acid, the addition of the above-mentioned auxiliary agent improves the mutual miscibility between various substances such as bamboo oil, etc., and on the other hand, because of its anionic nature, so that the electrostatic adsorption of the waterproofing agent is balanced, and at the same time, dimethylolpropionic acid also has the function as a color stabilizer, therefore, the product has strong waterproof performance, and the degradation rate of the product can be improved in the natural degradation process after being discarded.

The unique structure of the bamboo fiber maximizes the polar attraction and the non-polar attraction between fiber molecules and dye molecules, and in the dyeing process, the sodium chloride with the concentration of 60g/L and the sodium hydroxide with the concentration of 90g/L are added in batches, so that on one hand, the batch addition of the sodium chloride is beneficial to the dye uptake of the fiber, and on the other hand, along with the progress of dyeing, the cellulose crystallization area is increased, the dye uptake is greatly reduced, the dye uptake of the cellulose fiber is seriously influenced, the addition of the 60g/L sodium chloride and the 20g/L sodium hydroxide can effectively inhibit the growth of the cellulose crystallization area, and the later natural environment degradation is facilitated; the direct dye is dissociated into pigment anions in the solution to dye the cellulose fibers, and the weak cationic property of the water-proofing agent also has certain help for balancing the anionic property of the cellulose fibers to a certain extent, but due to the charge balance between the anionic emulsifier and the water-proofing agent, the water-proofing agent molecules and the dyeing agent molecules cannot compete and combine with the cellulose fibers. In addition, through the trial of researchers, it was found that when the dyeing temperature exceeded 65 ℃, the lattice of the cellulose fiber began to change, and as the temperature or alkali concentration increased, the fiber contracted strongly, the lumen became smaller, the fiber expanded strongly, and the fiber twisted longitudinally. Therefore, although the temperature is raised to a certain extent to help the dye-uptake and the dye-uptake speed, the temperature is not too high, the embodiment is used for dyeing in different stages in a three-stage manner, the temperature is approximately low, the dye-uptake is facilitated, and the dye is uniformly dyed.

Detailed Description

Example 1

The preparation method of the colored pulp molded product comprises the following steps:

s1, cooking raw bamboos in boiling water for 1 hour, then performing disintegration and grinding to obtain bamboo fibers, selecting bamboo fibers of 200-400 meshes, adding water with the weight 2 times that of the bamboo fibers, and stirring to obtain bamboo fiber slurry;

s2, taking 55 parts of the prepared bamboo fiber slurry, adding 25 parts of adhesive, 0.5 part of waterproof agent and 0.5 part of anionic emulsifier, and uniformly mixing;

in this embodiment, the binder is selected from water, carboxymethyl cellulose, and starch according to a ratio of 1: 1: 2, mixing the components in parts by weight; the waterproof agent is selected from acrylate copolymer, anionic emulsifiers of dimethylolpropionic acid and dimethylolbutyric acid 1: 1, mixing;

s3, diluting direct suntan or direct suntan orange to 0.5 mass% by using soft water at the temperature of 60-80 ℃, and adding the diluted solution into the prepared bamboo fiber mixture;

s4, dyeing the bamboo fiber mixture added with the fuel for 15min at the dyeing temperature of 50 ℃; then, the dyeing is carried out for 5min at the dyeing temperature of 60 ℃, and the dyeing is carried out for 5min at the dyeing temperature of 45 ℃.

In the dyeing process, 0.1 part by weight of sodium chloride with the concentration of 60g/L and 0.2 part by weight of sodium hydroxide with the concentration of 20g/L are added at intervals of 8-10 minutes and repeated for 3 times; and 0.1 part by weight of soda ash of 25g/L is added while the sodium chloride solution is added for the first time;

s5, extending a vacuum molding machine into the formed bamboo fiber mixture suspension, carrying out vacuum suction molding, carrying out vacuum negative pressure of 0.04Mpa, dehydrating to obtain a wet blank, extruding through an upper mold and a lower mold of the molding machine, dehydrating to obtain a blank, carrying out co-dehydration for 30 seconds, and finally placing the blank in a hot-pressing forming machine, and drying and forming at the temperature of 100 ℃.

Example 2

s1, cooking raw bamboos in boiling water for 2 hours, then performing disintegration and grinding to obtain bamboo fibers, selecting bamboo fibers of 200-400 meshes, adding water with the weight 2 times that of the bamboo fibers, and stirring to obtain bamboo fiber slurry;

s2, taking 75 parts of the prepared bamboo fiber slurry, adding 35 parts of an adhesive, 0.7 part of a waterproof agent and 0.8 part of an anionic emulsifier, and uniformly mixing;

in this embodiment, the binder is selected from water, carboxymethyl cellulose, and starch according to a ratio of 1: 2: 1 part by weight; the water-proofing agent is selected from acrylate copolymer, and the anionic emulsifier is dimethylolpropionic acid;

In the dyeing process, 0.2 part by weight of sodium chloride with the concentration of 60g/L and 0.1 part by weight of sodium hydroxide with the concentration of 20g/L are added at intervals of 8-10 minutes and repeated for 3 times; and 0.2 part by weight of soda ash of 25g/L is added while the sodium chloride solution is added for the first time;

s5, extending a vacuum molding machine into the formed bamboo fiber mixture suspension, carrying out vacuum suction molding, carrying out vacuum negative pressure of 0.07Mpa, dehydrating to obtain a wet blank, extruding through an upper mold and a lower mold of the molding machine, dehydrating to obtain a blank, carrying out co-dehydration for 30 seconds, and finally placing the blank in a hot-pressing forming machine, and drying and forming at the temperature of 100 ℃.

Example 3

s2, taking 65 parts of the prepared bamboo fiber slurry, adding 30 parts of adhesive, 0.6 part of waterproof agent and 0.7 part of anionic emulsifier, and uniformly mixing;

in this embodiment, the binder is selected from water, carboxymethyl cellulose, and starch according to a ratio of 1: 1: 1 part by weight; the waterproof agent is acrylate copolymer, and the anionic emulsifier is dimethylolbutyric acid;

In the dyeing process, 0.1 part by weight of 60g/L sodium chloride is added at intervals of 8-10 minutes, and the process is repeated for 3 times;

s5, extending a vacuum molding machine into the formed bamboo fiber mixture suspension, carrying out vacuum suction molding, carrying out vacuum negative pressure of 0.06Mpa, dehydrating to obtain a wet blank, extruding through an upper mold and a lower mold of the molding machine, dehydrating to obtain a blank, carrying out co-dehydration for 30 seconds, and finally placing the blank in a hot-pressing forming machine, and drying and forming at the temperature of 100 ℃.

Example 4

s2, taking 70 parts of the prepared bamboo fiber slurry, adding 32 parts of adhesive, 0.6 part of waterproof agent and 0.6 part of anionic emulsifier, and uniformly mixing;

in this embodiment, the binder is selected from water, carboxymethyl cellulose, and starch according to a ratio of 1: 2: 2, mixing the components in parts by weight; the waterproof agent is selected from acrylate copolymer, anionic emulsifiers of dimethylolpropionic acid and dimethylolbutyric acid 1: 1, mixing;

In the dyeing process, 0.2 part by weight of sodium hydroxide with the concentration of 20g/L is added at intervals of 8-10 minutes, and the process is repeated for 3 times; and 0.1 part by weight of soda ash of 25g/L is added while the sodium chloride solution is added for the first time;

Example 5

s2, taking 55 parts of the prepared bamboo fiber slurry, adding 60 parts of an adhesive, 0.6 part of a waterproof agent and 0.6 part of an anionic emulsifier, and uniformly mixing;

In the dyeing process, 0.1 part by weight of sodium hydroxide with the concentration of 20g/L is added at intervals of 8-10 minutes, and the process is repeated for 3 times; and 0.1 part by weight of soda ash of 25g/L is added while the sodium chloride solution is added for the first time;

Example 6

s2, taking 55 parts of the prepared bamboo fiber slurry, adding 73 parts of adhesive, 0.7 part of waterproof agent and 0.8 part of anionic emulsifier, and uniformly mixing;

In the dyeing process, 0.2 part by weight of 60g/L sodium chloride is added at intervals of 8-10 minutes, and the process is repeated for 3 times; and 0.1 part by weight of soda ash of 25g/L is added while the sodium chloride solution is added for the first time;

S6, after the paper pulp is molded, atomizing UV gloss oil spraying is carried out on the surface of the paper pulp.

Comparative example 1

s1, cooking bagasse in boiling water for 1.5 hours, then crushing the bagasse in a crushing tank at the speed of 900-1200 rpm for 8 minutes, and adding water with the weight 2.5 times of that of the bagasse and stirring the mixture into fiber slurry;

s2, taking 55 parts of the prepared fiber pulp, adding 28 parts of adhesive and 0.7 part of waterproof agent, and uniformly mixing the direct suntan or direct suntan orange in a disintegration tank at 80 ℃ at 500-600 rpm for 9 minutes;

in this embodiment, the binder is selected from water, carboxymethyl cellulose, and starch according to a ratio of 1: 1: 1.6 parts by weight; the water-proofing agent is sodium methyl silicate;

s3, extending a part of a molding machine into the formed mixture suspension, sucking a mold in vacuum, dehydrating the mixture suspension into a wet blank under the vacuum negative pressure of 0.04-0.07 Mpa, extruding the wet blank by an upper mold and a lower mold of the molding machine, dehydrating the wet blank into a blank, co-dehydrating for 30 seconds, and finally drying and molding the blank in a hot-pressing molding machine at the temperature of 130-150 ℃.

Comparative example 2

s1, cooking bagasse and rice straws in boiling water for 1.5 hours, then crushing the bagasse and the rice straws in a crushing tank at the speed of 900-1200 rpm for 8 minutes, adding water with the weight 2.5 times of that of the bagasse and the rice straws, and stirring the mixture into fiber slurry;

s2, taking 55 parts of the prepared fiber pulp, adding 28 parts of adhesive and 0.7 part of waterproof agent, and uniformly mixing the direct suntan or the direct suntan orange in a 70 ℃ disintegration tank at 500-600 rpm for 9 minutes;

in this embodiment, the binder is selected from water, carboxymethyl cellulose, and starch according to a ratio of 1: 1: 1.6 parts by weight; the water-proofing agent is selected from acrylate copolymer;

Comparative example 3

s1, cooking bagasse and rice straws in boiling water for 1.5 hours, then crushing the bagasse and the rice straws in a crushing tank at the speed of 900-1200 rpm for 8 minutes, adding water with the weight being 3 times of that of the bagasse and the rice straws, and stirring the mixture into fiber slurry;

s2, taking 75 parts of the prepared fiber pulp, adding 30 parts of adhesive and 0.8 part of waterproof agent, and uniformly mixing the direct suntan or the direct suntan orange in a 70 ℃ disintegration tank at 500-600 rpm for 9 minutes;

in this embodiment, the binder is selected from water, carboxymethyl cellulose, and starch according to a ratio of 1: 1: 1 part by weight; the water-proofing agent is selected from acrylate copolymer;

Test examples

Performance testing

1. Appearance: example 1-example 6: normal color, no peculiar smell, flat surface, no oil stain, dust or other foreign matters, no fracture and no holes; comparative example 1 to comparative example 3: normal color, little peculiar smell, flat surface, no oil stain, dust or other foreign matters, no fracture and no holes;

2. color uniformity: example 1-example 6: the dyeing color and the texture are uniform; comparative example 1 to comparative example 3: the color dyeing is obviously uneven and shows inconsistent depth.

3. Gloss, a measure of optical smoothness, measured using a gloss test chart, using a 45 ° measurement (1 unit in 1 gloss); water resistance, spraying by water mist at room temperature for 48 hours; the amount of deformation was measured under a pressure of 830N.

The test data are shown in the following table:

	degree of gloss	Water resistance	Deformation/mm
				Example 1	358	Without leakage	≤2
Example 2	356	Without leakage	≤2
				Example 3	321	Without leakage	≤2
Example 4	363	Without leakage	≤2
				Example 5	346	Without leakage	≤2
Example 6	383	Without leakage	≤2
				Comparative example 1	289	Without leakage	≤2
Comparative example 2	285	Without leakage	≤2
				Comparative example 3	280	Without leakage	≤2

As can be seen from the above data, the gloss values of examples 1 to 6 were all good, all being 300 or more, and the raw fibers used in the comparative examples were different, being slightly inferior in gloss value to those of examples, and being good in both water resistance and deformation.

4. Degradation degree related test index

The experimental study is carried out by using a soil burying method and a natural climate exposure method, each example or a comparison example is repeated for 20-30 times, and then the three indexes of the crystallinity, the tensile strength and the weight loss rate are selected for measurement, and the crystallinity is measured by 4.1: the crystallinity was measured by the X-ray rotational crystal method using a Rigaku D/max-1200X-ray diffractometer in Japan,

the measurement conditions were: the method comprises the following steps of Cu target, Kalpha ray, monochromatic filtering, 40kV, 300mA, step diameter scanning, 3 seconds per step, step width of 0.10 degree and scanning range of 20.6-40 degrees. The calculation formula is as follows: crystallinity CrI (%) ═ FK/(FK + FA) ] × 100

Wherein: FK is crystalline region area (m 2); FA is the area of the amorphous region (m2)

The test data are shown in the following table:

	after 4 weeks	After 6 weeks	After 8 weeks	After 12 weeks
					Example 1	71.02％	64.12％	63.33％	62.35％
Example 2	68.02％	66.47％	64.37％	－
					Example 3	71.32％	69.49％	64.01％	62.35％
Example 4	75.07％	75.45％	68.33％	59.16％
					Example 5	76.32％	71.11％	63.58％	－
Example 6	75.02％	73.15％	67.48％	－
					Comparative example 1	91.27％	87.36％	84.69％	89.64％
Comparative example 2	92.42％	90.84％	91.92％	89.56％
					Comparative example 3	91.12％	90.11％	88.57％	88.02％

From the above data, it can be seen that the change of the crystallinity of the cellulose in the first 4 weeks is large and decreased by about 30%, and then the change becomes relatively slow in the last 6 to 12 weeks, but the change of the crystallinity is relatively small in the whole 12 weeks compared to the comparative example, and the breakage of the long chain of the cellulose is difficult, so that the structure of the crystalline region is relatively compact.

4.2 measurement of weight loss ratio

The sample was placed in a desiccator to be equilibrated for two days, weighed, and the weight loss rate was calculated.

Weight loss ratio (WL)/% (W0-W1)/W0 × 100

Wherein: w0 is the initial mass (g) of the specimen; w1 is the mass (g) of the sample after photodegradation treatment.

	4 weeksRear end	After 6 weeks	After 8 weeks	After 12 weeks
					Example 1	91.5％	80.2％	75.0％	61.5％
Example 2	91.2％	89.3％	78.9％	59.4％
					Example 3	93.8％	89.0％	72.1％	58.2％
Example 4	94.6％	88.8％	69.1％	65.2％
					Example 5	86.3％	80.6％	75.4％	60.1％
Example 6	92.7％	86.4％	77.1％	63.9％
					Comparative example 1	96.3％	93.1％	85.3％	84.6％
Comparative example 2	93.9％	89.6％	81.3％	88.1％
					Comparative example 3	91.1％	87.5％	82.3％	83.4％

From the data of water loss rate, which can be combined with the previous data, the fiber structure inside the sample begins to change with the changes of crystallinity and tensile strength, so that the quality of the samples of examples 1 to 5 begins to be significantly reduced with the passage of time, and example 6 has a UV film sprayed on the outer layer, so that the overall degradation becomes slower to some extent, but it can be seen that the comparative ratio is still significantly reduced.

It should be noted that the raw pulp is also suitable for other woody plants, herbaceous plants and waste paper besides the bamboo fiber used in the present invention.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. The preparation method of the colored pulp molded product is characterized by comprising the following steps:

55-75 parts of bamboo fiber slurry

25-35 parts of adhesive

0.5-0.7 part of waterproof agent

0.5-0.8 part of anionic emulsifier;

the waterproof agent is a cationic neutral sizing agent;

the anionic emulsifier is dimethylolpropionic acid and/or dimethylolbutyric acid;

(3) preparation of colored pulp comprising:

diluting direct sunless tanning or direct sunless orange to 0.5% mass concentration by using soft water at 60-80 ℃, and adding the diluted solution into the prepared bamboo fiber mixture;

adding 0.1-0.2 part by weight of sodium chloride with the concentration of 60g/L and/or 0.1-0.2 part by weight of sodium hydroxide with the concentration of 20g/L every 8-10 minutes, and repeating for at least 3 times; the method is divided into three dyeing stages in sequence, and comprises the following steps:

dyeing for 15min at the dyeing temperature of 50 ℃;

dyeing for 5min at the dyeing temperature of 60 ℃;

dyeing for 5min at the dyeing temperature of 45 ℃;

(4) and (3) molding pulp, namely feeding the colored pulp into a molding machine for dehydration and hot-press molding.

2. The method of manufacturing a colored pulp molded product according to claim 1, wherein 0.1 to 0.2 part by weight of 25g/L of soda ash is added simultaneously with the first addition of the sodium chloride solution.

3. The method for producing a colored pulp molded article according to claim 1 or 2, characterized by further comprising a step of spraying atomized UV varnish on the surface of the pulp after molding.

4. The method for producing a colored pulp molded product according to claim 1, wherein the binder is prepared by mixing water, carboxymethyl cellulose, and starch in a ratio of 1: 1-2: 1-2 parts by weight.

5. The method for producing a colored pulp molded product according to claim 1, wherein the stirring speed in the steps (1) and (2) is 900rpm to 1200rpm, and the stirring time is 15min to 20 min.

6. The method for producing a colored pulp molded product according to claim 1, wherein the step (4) comprises conveying the pulp to a vacuum suction molding machine, dehydrating, extruding, dehydrating again to form a preform, and drying by hot pressing to obtain a pulp molded product; the dehydration time is 30-60 seconds, and the wet blank is dried at 100 ℃ for 40-60 minutes.

7. A pulp molded article produced by the method for producing a colored pulp molded article according to any one of claims 1 to 6.