A process for the production of dry plant stalk fibres

Abstract

The present application relates to the technical field of plant fiber preparation, and discloses a process for preparing dry plant straw fiber, S1, raw material heating and extrusion treatment: determining the cutting length of plant straw, soaking time, feeding amount, processing temperature and screw rotation speed, and extruding the plant straw into fiber slurry through a screw extruder; S2, slurry detonation treatment: processing the fiber slurry into fiber coarse material through a steam explosion machine; S3, coarse material pretreatment: adding the fiber coarse material into a pretreatment liquid for pretreatment; S4, bleaching treatment: adding the pretreated straw cellulose into a bleaching liquid for bleaching treatment; S5, deashing treatment: adding the bleached straw cellulose into a deashing liquid for deashing treatment; S6, drying and crushing treatment: drying and crushing the clean straw cellulose. The plant fiber prepared by the present application has the characteristics of high methoxyl content, high dynamic viscosity, low lignin content and low ash content, and is of high quality and excellent performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plant fiber preparation, and particularly relates to a process for preparing dry plant straw fiber. BACKGROUND

[0002] With the economic growth of China, resources and environment have become the restricting factors affecting future development. Under this situation, it is inevitable to develop and utilize renewable resources; among which, straw fiber is a kind of natural fiber, has good biodegradability, can replace wood to act on papermaking, production of board and handicraft, production of activated carbon, etc.; and has rich sources, low price, good social, economic and ecological benefits, and is widely used.

[0003] A plant fiber material and a preparation process thereof are disclosed in Chinese patent (publication number CN1141373A), the plant fiber powder of which is directly obtained after being crushed or after being subjected to an alkali treatment process. The patent technology has the characteristics of small alkali consumption and alkali pollution, high fiber yield, etc., but the content of methyl fiber and dynamic viscosity is not high, and the content of lignin and ash is high, and the quality is poor. SUMMARY

[0004] The present application aims to provide a process for preparing dry plant straw fiber to solve the problems in the background technology.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A process for preparing dry plant straw fiber, comprising the following steps:

[0007] S1, raw material heating and extrusion treatment: according to the comprehensive requirements of fiber yield, fiber length-width ratio and tensile strength, the plant straw is cut into sections and soaked, and then sent into the temperature of a screw extruder, and the feeding amount, processing temperature and screw rotation speed are adjusted, so that the plant straw is extruded into fiber slurry;

[0008] S2, slurry initiation treatment: after the water in the fiber slurry is separated and spun dry, it is sent into a steam explosion machine, and is subjected to steam explosion treatment under a pressure of 1.8-2.2 MPa for 90-150 s, and is taken out after being kept under pressure for 10-15 min, to obtain fiber coarse material;

[0009] S3, coarse material pretreatment: the fiber coarse material is added into a pretreatment liquid according to a solid-liquid mass ratio of 1:(20-25), and is continuously stirred, and is pretreated for 2-2.5 h, and after the pretreatment is completed, it is filtered and rinsed with water, to obtain pretreated straw cellulose;

[0010] S4, bleaching treatment: according to the solid-liquid mass ratio of 1: (25-30), the pretreated straw cellulose is added into the bleaching liquid, heated to 55-60℃ and continuously stirred, bleaching treatment is carried out for 3-4h, after bleaching treatment, filtration and water rinsing, bleaching treated straw cellulose is obtained;

[0011] S5, deashing treatment: according to the solid-liquid mass ratio of 1: (25-30), the bleaching treated straw cellulose is added into the deashing liquid, continuously stirred, deashing treatment is carried out for 30-45min, after deashing treatment, filtration and water rinsing, clean straw cellulose is obtained;

[0012] S6, drying and crushing treatment: the clean straw cellulose is dried in the oven at 85-90℃ for 6-8h, then put into the crusher and crushed, passed through the 40 mesh sieve.

[0013] As a further scheme of the present application: in the S1 step, the relationship equation of fiber yield and the segment length of plant straw, soaking time, feeding amount, processing temperature and screw rotation speed is as follows:

[0014] y1=A+α1x2-β1x4-γ1x5-δ1x1x3-ε1x1x5+η1x4x5 (1)

[0015] In the above formula (1), y1 is the fiber yield, x1 is the straw length, x2 is the soaking time, x3 is the processing temperature, x4 is the screw rotation speed, x5 is the feeding amount, A is the constant coefficient of fiber yield, α1, β1, γ1, δ1, ε1, η1 are the variable coefficients of fiber yield.

[0016] As a further scheme of the present application: in the S1 step, the relationship equation of fiber length-width ratio and the segment length of plant straw, soaking time, feeding amount, processing temperature and screw rotation speed is as follows:

[0017] y2=B+α2x5+β2x1x3-γ2x1x5-δ2x2x5+ε2x3x4-η2x3x5-λ2x4x5 (2)

[0018] In the above formula (2), y2 is the fiber length-width ratio, x1 is the straw length, x2 is the soaking time, x3 is the processing temperature, x4 is the screw rotation speed, x5 is the feeding amount, B is the constant coefficient of fiber length-width ratio, α2, β2, γ2, δ2, ε2, η2, λ2 are the variable coefficients of fiber length-width ratio.

[0019] As a further scheme of the present application: in the S1 step, the relationship equation of tensile strength and the segment length of plant straw, soaking time, feeding amount, processing temperature and screw rotation speed is as follows:

[0020] y3=C-α3x1-β3x3-γ3x5-δ3x1x4+ε3x2x3 (3)

[0021] In the above formula (3), y3 is the tensile strength, x1 is the straw length, x2 is the soaking time, x3 is the processing temperature, x4 is the screw rotation speed, x5 is the feeding amount, C is the constant coefficient of the tensile strength, α3, β3, γ3, δ3, ε3 are the variable coefficients of the tensile strength; wherein the tensile strength refers to that the fiber slurry extruded in the S1 step is prepared into a slurry with a mass of 5%, is beaten to a beating degree of 35°SR, is sheeted, is dried into a film, and the tensile strength is tested.

[0022] As a further scheme of the present application: in the S3 step, the pretreatment liquid is a mixture of 0.005-0.008 mol / L sodium hydroxide solution and 0.007-0.012 mol / L sodium sulfide solution in a mass ratio of 1:1.

[0023] As a further scheme of the present application: in the S4 step, the bleaching liquid is a mixture of 0.04-0.06 mol / L hydrogen peroxide and 0.04-0.06 mol / L sodium hydroxide solution in a mass ratio of 2:1.

[0024] As a further scheme of the present application: in the S5 step, the deashing liquid is a mixture of 2.5-4 mol / L sodium fluoride solution and 0.5-0.7 mol / L hydrochloric acid solution in a mass ratio of 1:1.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] The present application determines the cutting length of the plant straw, the soaking time, the feeding amount, the processing temperature and the screw rotation speed according to the comprehensive requirements of the fiber yield, the fiber length-width ratio and the tensile strength, extrudes the plant straw into a fiber slurry through a screw extruder, processes the fiber slurry into a fiber coarse material through a steam explosion machine, and then sequentially performs pretreatment, bleaching treatment and deashing treatment, and finally dries and crushes the obtained plant fiber; the prepared plant fiber has the characteristics of high methylene content, high dynamic viscosity, low lignin content and low ash content, and has high quality and excellent performance. DETAILED DESCRIPTION

[0027] For example, the plant straw is rice straw, and according to experience and experimental analysis, A, α1, β1, γ1, δ1, ε1 and η1 in equation (1) are respectively taken as 97.65, 0.61, 0.95, 1.43, 0.31, 0.24 and 0.03, and then equation (1) is as follows:

[0028] y1=97.65+0.61x2-0.95x4-1.43x5-0.31x1x3-0.24x1x5+0.03x4x5 (4);

[0029] B, a2, b2, g2, d2, e2, h2, l2 in equation (2) are respectively 5.31, 0.52, 0.01, 0.02, 0.01, 0.01, 0.01 and 0.01, then equation (2) is as follows:

[0030] y2=5.31+0.52x5+0.01x1x3-0.02x 11 x5-0.01x2x5+0.01x3x4-0.01x3x5-0.01x4x5 (5));

[0031] C, a3, b3, g3, d3, e3 in equation (3) are respectively 10.42, 0.52, 0.01, 0.02, 0.01 and 0.01, then equation (3) is as follows:

[0032] y3=10.42-1.45x1-0.06x3-0.04x5-0.03x1x4+0.01x2x3 (6);

[0033] In the above formula (4), (5), (6), x1 is the length of straw, cm; x2 is the soaking time, h; x3 is the processing temperature, ℃; x4 is the screw rotation speed, r / min; x5 is the feeding amount, g / min; y1 is the fiber yield, %; y2 is the fiber length-width ratio; y3 is the tensile strength, N;

[0034] If the fiber yield y1 is required to be no less than 70%, the fiber length-width ratio y2 is required to be no less than 5, and the tensile strength y3 is required to be no less than 6.5N, then the length of straw x1 is 3-6cm; the soaking time x2 is 18-24h; the processing temperature x3 is 75-85℃; the screw rotation speed x4 is 95-115r / min; the feeding amount x5 is 35-40g / min; the fiber yield y1, the fiber length-width ratio y2 and the tensile strength y3 obtained according to formula (4), (5), (6) all meet the requirements;

[0035] Example One

[0036] In the embodiment of the present application, a process for preparing dry plant straw fiber comprises the following steps:

[0037] S1, raw material heating extrusion treatment: according to the comprehensive demand that the fiber yield is not less than 70%, the fiber length-width ratio is not less than 5, and the tensile strength is not less than 6.5N, the plant straw is cut into 3cm, soaked for 18h, and then sent to the screw extruder temperature, and the feeding amount is adjusted to 35g / min, the processing temperature is 75℃, and the screw rotation speed is 95r / min, so that the plant straw is extruded into fiber slurry;

[0038] S2, slurry initiation treatment: after the water in the fiber slurry is separated and spun dry, it is sent to a steam explosion machine, treated at 1.8MPa pressure for 150s, and taken out after pressure maintaining for 15min, to obtain fiber coarse material;

[0039] S3, coarse material pretreatment: the fiber coarse material is added into a pretreatment liquid in a solid-liquid mass ratio of 1:20, and continuously stirred for pretreatment for 2h, after the pretreatment, filtered and rinsed with water, to obtain pretreated straw cellulose; the pretreatment liquid is a mixture of 0.005mol / L sodium hydroxide solution and 0.007mol / L sodium sulfide solution in a mass ratio of 1:1;

[0040] S4, bleaching treatment: the pretreated straw cellulose is added into a bleaching liquid in a solid-liquid mass ratio of 1:25, heated to 55℃ and continuously stirred for bleaching treatment for 4h, after the bleaching treatment, filtered and rinsed with water, to obtain bleached straw cellulose; the bleaching liquid is a mixture of 0.04mol / L hydrogen peroxide and 0.04mol / L sodium hydroxide solution in a mass ratio of 2:1;

[0041] S5, deashing treatment: the bleached straw cellulose is added into a deashing liquid in a solid-liquid mass ratio of 1:25, and continuously stirred for deashing treatment for 30min, after the deashing treatment, filtered and rinsed with water, to obtain clean straw cellulose; the deashing liquid is a mixture of 2.5mol / L sodium fluoride solution and 0.5mol / L hydrochloric acid solution in a mass ratio of 1:1;

[0042] S6, drying and crushing treatment: the clean straw cellulose is dried in an 85℃ oven for 8h, and then put into a crusher for crushing, and sieved through a 40 mesh sieve.

[0043] Example two

[0044] In the embodiment of the application, a process for preparing dry plant straw fiber comprises the following steps:

[0045] S1, raw material heating extrusion treatment: according to the comprehensive demand that the fiber yield is not less than 70%, the fiber length-width ratio is not less than 5, and the tensile strength is not less than 6.5N, the plant straw is cut into 4cm, soaked for 21h, and then sent to the screw extruder temperature, and the feeding amount is adjusted to 38g / min, the processing temperature is 80℃, and the screw rotation speed is 105r / min, so that the plant straw is extruded into fiber slurry;

[0046] S2, slurry initiation treatment: after the water in the fiber slurry is separated and spun dry, it is sent to a steam explosion machine, treated at a pressure of 1.8-2.2MPa for 120s, and taken out after pressure maintaining for 12min, to obtain a fiber coarse material;

[0047] S3, coarse material pretreatment: the fiber coarse material is added to a pretreatment liquid in a solid-liquid mass ratio of 1:22, and continuously stirred for pretreatment for 2.2h, after which it is filtered and rinsed with water to obtain pretreated straw cellulose; the pretreatment liquid is a mixture of 0.006mol / L sodium hydroxide solution and 0.01mol / L sodium sulfide solution in a mass ratio of 1:1;

[0048] S4, bleaching treatment: the pretreated straw cellulose is added to a bleaching liquid in a solid-liquid mass ratio of 1:28, heated to 58℃ and continuously stirred for bleaching treatment for 3.5h, after which it is filtered and rinsed with water to obtain bleached straw cellulose; the bleaching liquid is a mixture of 0.05mol / L hydrogen peroxide and 0.05mol / L sodium hydroxide solution in a mass ratio of 2:1;

[0049] S5, desalination treatment: the bleached straw cellulose is added to a desalination liquid in a solid-liquid mass ratio of 1:28, and continuously stirred for desalination treatment for 38min, after which it is filtered and rinsed with water to obtain clean straw cellulose; the desalination liquid is a mixture of 3.2mol / L sodium fluoride solution and 0.6mol / L hydrochloric acid solution in a mass ratio of 1:1;

[0050] S6, drying and crushing treatment: the clean straw cellulose is dried in an oven at 88℃ for 7h, and then crushed in a crusher and passed through a 40-mesh sieve.

[0051] Example Three

[0052] In the embodiment of the present application, a process for preparing dry plant straw fiber comprises the following steps:

[0053] S1, raw material heating extrusion treatment: according to the comprehensive demand that the fiber yield is not less than 70%, the fiber length-width ratio is not less than 5, and the tensile strength is not less than 6.5N, the plant straw is cut into 6cm, soaked for 24h, and then sent to the screw extruder temperature, and the feeding amount is adjusted to 40g / min, the processing temperature is 85℃, and the screw rotation speed is 115r / min, so that the plant straw is extruded into fiber slurry;

[0054] S2, slurry initiation treatment: after the water in the fiber slurry is separated and spun dry, it is sent to a steam explosion machine, treated at 2.2MPa pressure for 150s, and taken out after pressure maintaining for 10min to obtain fiber coarse material;

[0055] S3, coarse material pretreatment: the fiber coarse material is added to the pretreatment liquid in a solid-liquid mass ratio of 1:25, and continuously stirred for 2.5h of pretreatment, then filtered and rinsed with water to obtain pretreated straw cellulose; the pretreatment liquid is a mixture of 0.008mol / L sodium hydroxide solution and 0.012mol / L sodium sulfide solution in a mass ratio of 1:1;

[0056] S4, bleaching treatment: the pretreated straw cellulose is added to the bleaching liquid in a solid-liquid mass ratio of 1:30, heated to 60℃ and continuously stirred for 3h of bleaching treatment, then filtered and rinsed with water to obtain bleached straw cellulose; the bleaching liquid is a mixture of 0.06mol / L hydrogen peroxide and 0.06mol / L sodium hydroxide solution in a mass ratio of 2:1;

[0057] S5, deashing treatment: the bleached straw cellulose is added to the deashing liquid in a solid-liquid mass ratio of 1:30, and continuously stirred for 45min of deashing treatment, then filtered and rinsed with water to obtain clean straw cellulose; the deashing liquid is a mixture of 4mol / L sodium fluoride solution and 0.7mol / L hydrochloric acid solution in a mass ratio of 1:1;

[0058] S6, drying and crushing treatment: the clean straw cellulose is dried in a 90℃ oven for 6h, then crushed in a crusher and sieved through a 40 mesh sieve.

[0059] In order to better illustrate the technical effect of the present application, the following test is described:

[0060] The process for preparing dry plant straw fiber disclosed in Chinese patent (publication date: August 17, 2016, publication number CN105856372A) is selected as Comparative Example 1; the plant fiber material and its preparation process disclosed in Chinese patent (publication date: January 29, 1997, publication number CN1141373A) is selected as Comparative Example 2;

[0061] The plant fibers prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were taken respectively, and the hemicellulose content (unit: 100%), dynamic viscosity (unit: mPa·s), lignin content (unit: 100%), ash content (unit: 100%) were tested respectively, and recorded in Table 1 below;

[0062] Table 1 Performance analysis table of plant fiber

[0063]

[0064] Therefore, Table 1 can be analyzed: the hemicellulose content and dynamic viscosity of the plant fibers prepared in Example 1, Example 2 and Example 3 are significantly higher than those of Comparative Example 1 and Comparative Example 2; the lignin content and ash content of the plant fibers prepared in Example 1, Example 2 and Example 3 are significantly lower than those of Comparative Example 1 and Comparative Example 2.

[0065] Therefore, the plant fiber prepared by the present application has the characteristics of high hemicellulose content, high dynamic viscosity, low lignin content and low ash content, high quality and excellent performance.

[0066] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A process for producing dried plant straw fiber, characterized in that, Includes the following steps: S1. Raw material heating and extrusion treatment: Based on the comprehensive requirements of not less than 70%, fiber length-to-width ratio not less than 5, and tensile strength not less than 6.5N, plant straw is cut into 6cm pieces, soaked for 24 hours, and then fed into a screw extruder. The feed rate is adjusted to 40g / min, the processing temperature is 85℃, and the screw speed is 115r / min to extrude the plant straw into fiber pulp. S2. Pulp detonation treatment: After centrifuging to remove water from the fiber slurry, it is fed into a steam detonator and subjected to steam detonation treatment at a pressure of 1.8-2.2 MPa for 90-150 seconds. After holding the pressure for 10-15 minutes, it is taken out to obtain coarse fiber material. S3. Coarse material pretreatment: Add the coarse fiber to the pretreatment solution at a solid-liquid mass ratio of 1:20-25 and stir continuously for 2-2.5 hours. After pretreatment, filter and rinse with water to obtain pretreated straw cellulose. The pretreatment solution is a mixture of 0.005-0.008 mol / L sodium hydroxide solution and 0.007-0.012 mol / L sodium sulfide solution at a mass ratio of 1:

1. S4. Bleaching treatment: The pretreated straw cellulose is added to the bleaching solution at a solid-liquid mass ratio of 1:25-30. The solution is heated to 55-60℃ with continuous stirring for 3-4 hours. After bleaching, the solution is filtered and rinsed with water to obtain bleached straw cellulose. The bleaching solution is a mixture of 0.04-0.06 mol / L hydrogen peroxide and 0.04-0.06 mol / L sodium hydroxide solution at a mass ratio of 2:

1. S5. Deashing treatment: Add the bleached straw cellulose to the deashing solution at a solid-liquid mass ratio of 1:25-30, and stir continuously for 30-45 minutes. After the deashing treatment, filter and rinse with water to obtain clean straw cellulose. The deashing solution is a mixture of 2.5-4 mol / L sodium fluoride solution and 0.5-0.7 mol / L hydrochloric acid solution at a mass ratio of 1:

1. S6. Drying and pulverizing treatment: Place the clean straw cellulose in an oven at 85-90℃ and dry for 6-8 hours, then put it into a pulverizer and pulverize it through a 40-mesh sieve.

2. The process for producing dried plant straw fiber according to claim 1, characterized in that, In step S1, the relationship between fiber yield and the cut length of plant straw, soaking time, feed rate, processing temperature, and screw speed is as follows: In the above formula (1), For fiber yield, The length of the straw. Soaking time, For processing temperature, The screw speed is... This is the amount of feed. This is a constant coefficient for fiber yield. The coefficients for fiber yield are variable coefficients.

3. The process for producing dried plant straw fiber according to claim 1, characterized in that, In step S1, the relationship between the fiber aspect ratio and the cut length of the plant straw, soaking time, feed rate, processing temperature, and screw speed is as follows: In the above formula (2), The aspect ratio of the fiber. The length of the straw. Soaking time, For processing temperature, The screw speed is... This is the amount of feed. This is a constant coefficient representing the aspect ratio of the fiber. The variable coefficient is the aspect ratio of the fiber.

4. The process for producing dried plant straw fiber according to claim 1, characterized in that, In step S1, the relationship between tensile strength and the cut length of plant straw, soaking time, feed amount, processing temperature, and screw speed is as follows: In the above formula (3), For tensile strength, The length of the straw. Soaking time, For processing temperature, The screw speed is... This is the amount of feed. This is a constant coefficient for tensile strength. These are the variable coefficients for tensile strength.

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