Rubber wood PRC-APMP pulping process and finished pulp

Abstract

The invention belongs to the technical field of papermaking, and particularly relates to a rubber wood PRC-APMP pulping process and finished pulp. The rubber wood PRC-APMP pulping process comprises the following steps that S1, rubber wood chips are washed and then subjected to pre-steaming till the rubber wood chips are softened, and pretreated wood chips are obtained; s2, the pretreated wood chips are sequentially subjected to first-stage extrusion tearing, first-stage chemical liquid medicine presoaking, first-stage chemical reaction, second-stage extrusion tearing, second-stage chemical liquid medicine presoaking, second-stage chemical reaction and high-concentration pulping, and then coarse pulp is obtained; s3, performing pulp-gas separation on the coarse pulp, adding a chemical liquid medicine, and performing high-concentration bleaching to obtain bleached pulp; s4, performing low-concentration pulp grinding on the bleached pulp, adding a composite dispersing agent, and performing screening, washing and concentration to obtain finished pulp. The pulping process provided by the invention can effectively broaden pulping raw material resources, so that the cost of the pulping raw materials is lower, and the quality of the produced pulp is better.

Description

Technical Field

[0001] The present invention belongs to the technical field of papermaking, and particularly relates to a pulping process and finished pulp of rubber wood PRC-APMP. Background Art

[0002] The PRC-APMP process is a pulping process developed on the basis of the APMP (Alkaline Peroxide Mechanical Pluping) process. The key points of the process include pretreatment, chemical treatment in a disc refiner, etc., and the bleaching effect is better. The brief process of P-RC APMP used in the industrial production of our company is: wood chips → wood chip bin → wood chip washing → pre-steaming bin → screw extruder (chemical liquid addition) → reaction bin → main refiner → stuffing screw discharger (chemical liquid addition) → high-concentration bleaching tower → low-concentration refiner → pressure screen → finished pulp.

[0003] At present, the main raw materials of the PRC-APMP process are poplar and eucalyptus. With the continuous expansion of pulping production capacity and the increasingly strict environmental protection policies, the cultivation of eucalyptus and poplar has been significantly restricted. Especially for poplar, it has been difficult to meet the market demand. This has gradually shown a shortage in the supply of eucalyptus and poplar as pulping raw materials. In order to meet the growing demand of the pulping industry for fiber raw materials, the PRC-APMP pulping process urgently needs to find new alternative raw materials.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a pulping process and finished pulp of rubber wood PRC-APMP. The core innovation of the present invention is to use rubber wood as a pulping raw material and optimize the pulping process according to its characteristics, so as to ensure the pulp quality while reducing costs and expanding the selection range of pulping raw materials.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A pulping process of rubber wood PRC-APMP includes the following steps:

[0008] S1. Wash the rubber wood chips and then perform pre-steaming until they are softened to obtain pretreated wood chips;

[0009] S2. Sequentially perform first-stage extrusion tearing, first-stage chemical liquid pre-impregnation, first-stage chemical reaction, second-stage extrusion tearing, second-stage chemical liquid pre-impregnation, second-stage chemical reaction, and high-concentration grinding on the pretreated wood chips to obtain crude pulp;

[0010] S3. After separating the crude pulp from the pulp and gas, add chemical liquid and perform high-concentration bleaching to obtain bleached pulp;

[0011] S4. After subjecting the bleached pulp to low-concentration pulping, a composite dispersant is added, and then after screening, washing, and concentration, the finished pulp is obtained.

[0012] Further, in step S1, the density of the rubber wood chips is 0.1 - 0.4 g / cm 3 ; and / or, the size of the rubber wood chips has a length of 15 - 30 mm and a thickness of 3 - 5 mm.

[0013] and / or, the material level of the pre-steam distillation is ≥70%, and the temperature is 80 - 85 °C.

[0014] Further, in step S2, the speed of the first-stage extrusion and tearing is 50 - 100 rpm, the torque is 70 - 120 kN·m, and the power is 500 - 1000 kW; the speed of the second-stage extrusion and tearing is 50 - 100 rpm, the torque is 70 - 120 kN·m, and the power is 500 - 1000 kW.

[0015] Further, in step S2, in the chemical liquor for the first-stage chemical liquor pre-impregnation, the mass of sodium hydroxide relative to the absolute dry wood chips is 0.5 - 1.0%, the mass of hydrogen peroxide relative to the absolute dry wood chips is 1.0 - 1.5%, the mass of sodium silicate relative to the absolute dry wood chips is 0.1 - 1.0%, and the mass of DTPA relative to the absolute dry wood chips is 0.1 - 1.5%; the impregnation time of the first-stage chemical liquor pre-impregnation is 10 - 15 min;

[0016] and / or, in the chemical liquor for the second-stage chemical liquor pre-impregnation, the mass of sodium hydroxide relative to the absolute dry wood chips is 1.0 - 2.0%, the mass of hydrogen peroxide relative to the absolute dry wood chips is 2.0 - 5.0%, the mass of sodium silicate relative to the absolute dry wood chips is 0.1 - 1.0%, the mass of DTPA relative to the absolute dry wood chips is 0.5 - 2.0%, and the mass of the auxiliary agent relative to the absolute dry wood chips is 0.1 - 0.5%; the impregnation time of the second-stage chemical liquor pre-impregnation is 10 - 15 min.

[0017] Further, in step S2, the reaction temperature of the first-stage chemical reaction is 90 °C - 100 °C, the reaction time is 20 - 30 min, the reaction concentration is 20% - 30%, and the material level in the reaction tank is greater than 60%;

[0018] and / or, the reaction temperature of the second-stage chemical reaction is 90 °C - 100 °C, the reaction time is 20 - 30 min, the reaction concentration is 20% - 30%, and the material level in the reaction tank is greater than 60%.

[0019] Further, in step S2, the pulping concentration of the high-concentration pulping is 30 - 40%, the pulping power is 4.0 - 8.0 MW; the unit energy consumption for pulping is 300 - 600 kWh / ADMT.

[0020] Further, in step S3, the addition amounts of the chemical liquid medicines are as follows: the amount of sodium hydroxide used for the absolutely dry pulp is 2.0 - 5.0%, the amount of hydrogen peroxide used for the absolutely dry pulp is 4.0 - 10.0%, the amount of sodium silicate used for the absolutely dry pulp is 0.5 - 1.0%, the amount of DTPA used for the absolutely dry wood chips is 0.5 - 2.0%, and the mass of the auxiliary agent for the absolutely dry wood chips is 0.1 - 0.5%;

[0021] And / or, the bleaching time of the high - concentration bleaching is 70 - 90 minutes, the temperature is 70 - 90 °C, and the bleaching concentration is 25 - 30%.

[0022] Further, in step S4, the grinding concentration of the low - concentration grinding is 4 - 6%, the grinding power is 1000 - 1500 KW; the unit energy consumption for grinding is 50 - 100 kWh / ADMT.

[0023] Further, in step S4, the composite dispersant is a mixture of PAAS and AEO - 9, wherein the weight ratio of PAAS to AEO - 9 is 2:1; the dosage of the composite dispersant is 3 kg / ton of absolutely dry pulp;

[0024] And / or, the concentration of the finished pulp is 25 - 35%.

[0025] In addition, the present invention also provides a kind of finished pulp, which is made by the above - mentioned PRC - APMP pulping process of rubber wood; the brightness of the finished pulp is ≥75% ISO.

[0026] Compared with the prior art, the technical solution of the present invention has at least the following technical effects:

[0027] The PRC - APMP pulping process and its finished pulp provided by the present invention using rubber wood, while producing pulps with good performance, effectively broaden the pulping raw material resources, relieve the tense situation of raw material supply, reduce the pulping cost, solve the problems such as low production capacity of conventional hardwood chemimechanical pulping, and can provide chemimechanical pulp with high brightness, high bulk and high strength, which has positive significance for increasing the proportion of chemimechanical pulp in cultural paper, reducing production costs and saving wood resources, etc. Specific Embodiments

[0028] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. The process parameters without specific conditions noted in the following embodiments are usually in accordance with conventional conditions.

[0029] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0030] According to the first aspect of the present invention, there is provided a pulping process for rubber wood PRC-APMP, which comprises the following steps:

[0031] S1. Wash the rubber wood chips and then perform pre-steaming until they are softened to obtain the pre-treated chips.

[0032] S2. Sequentially perform first-stage extrusion tearing, first-stage chemical liquor pre-impregnation, first-stage chemical reaction, second-stage extrusion tearing, second-stage chemical liquor pre-impregnation, second-stage chemical reaction, and high-concentration refining on the pre-treated chips to obtain the rough pulp.

[0033] S3. After separating the pulp from the gas, add chemical liquor to the rough pulp and perform high-concentration bleaching to obtain the bleached pulp.

[0034] S4. After performing low-concentration refining on the bleached pulp, add a composite dispersant, and then perform screening, washing, and concentration to obtain the finished pulp.

[0035] The PRC-APMP pulping process of the present invention using rubber wood as the fiber raw material can effectively broaden the pulping raw material resources while producing pulp with good performance, relieve the tense situation of raw material supply, and reduce the pulping cost.

[0036] The main process of the rubber wood PRC-APMP pulping process provided by the embodiment of the present invention includes steps such as stock preparation, pretreatment, two-stage extrusion tearing, two-stage chemical liquor pre-impregnation, two-stage chemical reaction, rough pulp preparation, high-concentration bleaching, fine pulp preparation, and pulp storage. It is set to two stages because performing in stages can reduce the use of chemical agents. The stock preparation described in the embodiment of the present invention is: screening the rubber wood chips, removing large and thick chips and fine wood chips, and temporarily storing the screened chips in the chip bin. The present invention uses rubber wood for pulping, which is a brand-new raw material, effectively broadens the pulping raw material resources, and has carried out certain optimization in the pulping process flow according to its material characteristics.

[0037] Rubberwood, scientifically named Hevea spp., belongs to the genus Hevea in the Euphorbiaceae family and is a hardwood solid wood mainly derived from the main trunk of rubber trees. Most of the woods in this genus are tall trees, with rich latex in the bark. There are about more than 20 species of woods. It is native to tropical America and is widely cultivated in the tropical regions of Southeast Asia. The variety of rubberwood (Hevea brasiliensis) has been introduced in southern China. The commercial woods of this genus can all be called Rubberwood. After the rubber-producing cycle of rubber trees ends (usually 25 - 30 years), they will be cut down, providing a stable and sufficient raw material source for pulp and paper making. Rubberwood is considered a waste after its original use (rubber tapping), so the cost is relatively low. Using rubberwood as a pulping raw material not only increases the added value of the wood but also reduces the pressure on the logging of natural forests, which conforms to the concept of sustainable development.

[0038] In the embodiments of the present invention, the density of the rubberwood chips is 0.10 - 0.40 g / g / cm 3 . Based on the material characteristics of the rubberwood chips themselves, the embodiments of the present invention have made many innovative pulping attempts and optimized to a certain extent on the basis of the conventional broad-leaved wood PRC-APMP pulping process. The specifications of the rubberwood chips screened in the embodiments of the present invention include: the length of the chips is preferably 15 - 30 mm, the thickness is 3 - 5 mm, the qualified rate of the chips ≥ 90% (mass percentage), and the bark rate ≤ 0.5%.

[0039] In the embodiments of the present invention, the rubberwood chips in the chip bin are sent to the washer for washing after being metered. The washed and dehydrated chips are put into the pre-steaming bin for pre-steaming to soften the chips. During this pretreatment process, the temperature of the pre-steaming steam is 80 - 85 °C, which is beneficial to improving characteristics such as whiteness. And, in the embodiments of the present invention, the material level in the pre-steaming bin for pre-steaming ≥ 70%.

[0040] In the embodiments of the present invention, the pre-steamed chips are sent to the No. 1 screw extruder for the first-stage extrusion and tearing, and after the first-stage extrusion and tearing are completed, they are sent to the No. 1 pre-impregnator for the first-stage chemical liquid pre-impregnation. Among them, the speed of the first-stage extrusion and tearing is preferably 50 - 100 rpm (more preferably 70 - 90 rpm), the torque is 70 - 120 kN·m; the power is 500 - 1000 kW, and torque control is preferred.

[0041] In the embodiments of the present invention, the chemical liquid in the above-mentioned No. 1 pre-impregnator mainly contains an aqueous solution of alkaline hydrogen peroxide. Specifically, the dosage of sodium hydroxide for absolute dry chips is 0.5 - 1%, the mass of hydrogen peroxide for absolute dry chips is 1.0 - 1.5%, the mass of sodium silicate for absolute dry chips is 0.1 - 1.0%, and the mass of DTPA for absolute dry chips is 0.1 - 1.5%. The impregnation time of the first-stage chemical liquid pre-impregnation is 10 - 15 min.

[0042] A piece of chemically pre-impregnated wood is fed into the No. 1 reaction tank for a first-stage chemical reaction. The temperature of the reaction tank is 90 - 100 °C, the reaction time is preferably 20 - 30 min, and the reaction concentration is 20 - 30%; the material level in the reaction tank is greater than 60%. The amount of various chemical agents is appropriately increased in this stage of the process on the basis of the traditional chemi-mechanical pulp process conditions.

[0043] After the reaction in the No. 1 reaction tank is completed, it enters the No. 2 screw extruder for second-stage extrusion and tearing. The speed of the second-stage extrusion and tearing is 50 - 100 rpm (more preferably 70 - 90 rpm); the torque is 70 - 120 kN·m, the power is 500 - 1000 kW, and torque control is preferred. The wood after the second-stage tearing is sent into the No. 2 pre-impregnator for second-stage chemical liquid pre-impregnation. The specific amount of the chemical liquid in the No. 2 pre-impregnator is as follows: the amount of sodium hydroxide relative to the absolutely dry wood chips is 1.0 - 2.0%, the amount of hydrogen peroxide relative to the absolutely dry wood chips is 2.0 - 5.0%, the amount of sodium silicate relative to the absolutely dry wood chips is 0.1 - 1.0%, the amount of DTPA (diethylenetriaminepentaacetic acid) relative to the absolutely dry wood chips is 0.5 - 2.0%, and the amount of the auxiliary agent (silica-free bleaching control auxiliary agent, sourced from Jining Jin Hansi Environmental Protection Materials Co., Ltd., model BR005) relative to the quality of the absolutely dry wood chips is 0.1 - 0.5%. The impregnation time for the second-stage chemical liquid pre-impregnation is 10 - 15 min. It should be noted that the "auxiliary agents" involved in the present invention are all silica-free bleaching control auxiliary agents, sourced from Jining Jin Hansi Environmental Protection Materials Co., Ltd., model BR005.

[0044] The wood after the second-stage chemical liquid pre-impregnation is fed into the No. 2 reaction tank; the temperature of the No. 2 reaction tank is 90 - 100 °C, the reaction time is preferably 20 - 30 min, the reaction concentration is 20% - 30%, and the material level in the reaction tank is greater than 60%; after passing through the No. 2 reaction tank, the wood chips are sent to a high-consistency refiner for refining to obtain the rough pulp. The chemical reagents involved are common commercially available or self-produced chemical reagents in the art. For example, ion-exchange membrane method sodium hydroxide and self-produced sodium silicate products are used.

[0045] Specifically, the refining concentration of the high-consistency refining is 30 - 40%, the refining power is 4.0 - 8.0 MW; the unit energy consumption for refining is 300 - 600 kWh / ADMT; it is adjusted according to the degree of chemical pretreatment and the freeness after refining, etc.; the brightness of the obtained rough pulp can be 45 - 55% ISO.

[0046] In the embodiment of the present invention, the obtained crude pulp is separated by a cyclone separator, and then chemical liquor is added after the plug screw discharger and sent to a high-concentration bleaching tower for alkaline hydrogen peroxide bleaching. The mass concentration of the bleached pulp can be 25-30%. The addition amount of the chemical liquor is 2.0-5.0% of sodium hydroxide based on the dry pulp, 4.0-10.0% of hydrogen peroxide based on the dry pulp, 0.5-1.0% of sodium silicate based on the dry pulp, 0.5-2.0% of DTPA based on the dry wood chips, and 0.1-0.5% of the auxiliary agent based on the mass of the dry wood chips. Preferably, in the high-concentration bleaching process, the mass of sodium hydroxide based on the dry wood chips is 2.0-4.0%, the mass of hydrogen peroxide based on the dry pulp is 5.0-7.0%, the mass of sodium silicate based on the dry wood chips is 0.6-0.8%, the mass of DTPA based on the dry wood chips is 1.0-1.5%, the mass of the auxiliary agent based on the dry wood chips is 0.2-0.4%, the bleaching time is 70-90 minutes, the temperature is 70-90 °C, and the bleaching concentration is 25-30%. The bleaching time of the high-concentration bleaching is 70-90 minutes, the temperature is 70-90 °C, and the bleaching concentration is 25-30%.

[0047] Since rubber wood contains more resin, an appropriate dispersant is added after low-concentration grinding to disperse rubber and resin particles in the liquid and improve the fluidity of the pulp. In the embodiment of the present invention, the dispersant is a composite dispersant, specifically composed of a mixture of PAAS (sodium polyacrylate) and AEO-9 (fatty alcohol polyoxyethylene ether), wherein the weight ratio of PAAS to AEO-9 is 2:1; the dosage of the composite dispersant is 3 kg / absolute dry ton, and "absolute dry" refers to plant fiber raw materials without moisture.

[0048] In the embodiment of the present invention, the pulp after high-concentration bleaching is sent to a low-concentration grinder for fine grinding: the grinding concentration is 4.0-6.0%, the grinding power is 1000-1500 KW; the unit energy consumption of grinding is 50-100 kWh / ADMT; it is adjusted according to the degree of chemical pretreatment and the freeness after grinding, etc. After fine grinding, the pulp is added with a composite dispersant and then sent to an intermediate pulp tank and then screened by a pressure screen. The good pulp after screening is concentrated by a multi-disc concentrator to obtain the finished pulp; the screened residue pulp can be reground by a residue pulp grinder, and the finished pulp is stored in a pulp storage tower.

[0049] In the above-mentioned rubber wood PRC-APMP pulping process, as a preferred embodiment, the screen slot of the pressure screen is 0.15 mm, the inlet pulp concentration is 1.0-3.0%; the inlet pulp flow rate is 10000-12000 L / min; the pressure difference between the inlet and outlet is 0.3-0.4 kPa; the residue pulp / good pulp flow ratio is 35-50%. The vacuum degree of the multi-disc concentrator is -0.005-0.250 bar; the liquid level is greater than 90%; the inlet pulp flow rate is 7000-9000 L / min.

[0050] The slurry obtained by the rubber wood PRC-APMP pulping process as described above in the embodiments of the present invention has a concentration of 25-35%; its brightness is higher than 75% ISO, for example, 75-80% ISO.

[0051] According to the second aspect of the present invention, there is provided a finished pulp made by the above-mentioned rubber wood PRC-APMP pulping process. The present invention provides a PRC-APMP pulping process using rubber wood and its finished pulp slurry, which can solve problems such as low productivity in conventional hardwood chemimechanical pulping, and can provide chemimechanical pulp with high brightness, high bulk and high strength, which has positive significance for increasing the proportion of chemimechanical pulp in cultural paper, reducing production costs and saving wood resources.

[0052] The embodiments of the present invention will be described in detail below. Each example is provided by way of explanation of the present invention rather than limitation of the present invention. In fact, those skilled in the art will appreciate that modifications and variations can be made to the present invention without departing from the scope or spirit thereof. For example, features shown or described as part of one embodiment can be used in another embodiment to yield yet another embodiment. Accordingly, it is intended that the present invention cover such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0053] In the embodiments of the present invention, the experimental methods used are all conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial sources unless otherwise specified.

[0054] Example 1

[0055] In this example, a process and slurry comparison between rubber wood pulping and poplar wood pulping was carried out. The process parameters such as chip specifications and extrusion rate were the same. The specific comparison is as follows:

[0056] Among them, Tables 1 and 2 are the main process parameters in this example; Table 3 is the pulp index in this example.

[0057] Table 1

[0058]

[0059] Table 2

[0060]

[0061] Table 3

[0062] Degree of freeness ml 460 457 Bulk cm3 / g 3.36 2.87 Tear index mN·m2 / g 2.77 2.6 Breaking length Km 1.94 2.41 Tensile index Nm / g 19 23.61 Internal bond strength J / m2 56.2 63 Stiffness mN 320 366 Fiber bundle content % 0.09 0.07 Average fiber length mm 0.753 0.704 Average fiber width μm 22 20.8 Fine fiber content % 63.27 54.62 D65 brightness % 76.28 76 L 95.32 95.31 a -1.59 -1.55 b 10.47 10.66 Opacity % 90.93 91.36

[0063] As can be seen from Tables 1, 2, and 3 above, for the first pulping of rubberwood, the total alkali consumption is 56 kg, the total hydrogen peroxide consumption is 94 kg, and the whiteness of the pulp is 76.28% ISO. For the first pulping of poplar, the total alkali consumption is 56 kg, the total hydrogen peroxide consumption is 98 kg, and the whiteness of the pulp is 76.00% ISO. In the example of the present invention, after replacing the traditional P-RC APMP pulping raw materials (such as eucalyptus and poplar) with rubberwood, under the condition of the same alkali consumption and basically the same other chemicals, the whiteness of the pulp of rubberwood and poplar is basically the same. The bulk and tear index of the pulp of rubberwood are higher, while the tensile index, internal bond, and stiffness of poplar are higher. This preliminarily demonstrates the feasibility of rubberwood pulping.

[0064] Example 2

[0065] In this example, the alkali consumption and the consumption of other chemicals were appropriately increased on the basis of Example 1.

[0066] In this example, the pulping processes and pulp properties of rubberwood and poplar were compared in detail. On the premise of ensuring that the key process parameters such as chip size and extrusion rate are the same, the following specific comparative analysis was carried out:

[0067] Among them, Tables 4 and 5 are the main process parameters in this example; Table 6 is the pulp index in this example.

[0068] Table 4

[0069]

[0070] Table 5

[0071]

[0072] Table 6

[0073]

[0074] As can be seen from Tables 4, 5, and 6 above, for the second pulping of rubberwood, the total alkali consumption is 58 kg, the total hydrogen peroxide consumption is 94 kg, and the whiteness of the pulp is 78.64% ISO. For the second pulping of poplar, the total alkali consumption is 58 kg, the total hydrogen peroxide consumption is 96 kg, and the whiteness of the pulp is 76.71% ISO. After replacing the raw materials of traditional P-RC APMP pulping from eucalyptus and poplar with rubberwood in the example of the present invention, while keeping the total alkali consumption at 58 kg and the consumption of other chemicals basically the same, the whiteness of rubberwood is 1.93% ISO higher than that of poplar. The pulp made from rubberwood is excellent in terms of bulk and tear index, while poplar is more prominent in terms of tensile index, internal bond strength, and stiffness. However, compared with the data at an alkali consumption of 56 kg / t, the differences in the above properties between the two are significantly reduced. This further verifies the feasibility of rubberwood pulping.

[0075] Example 3

[0076] In this example, the amount of alkali and other chemicals used were appropriately increased based on Example 2.

[0077] In this example, the pulping processes and pulp properties of rubber wood and poplar wood were compared in detail. On the premise of ensuring that the key process parameters such as chip specifications and extrusion rates were the same, the following specific comparative analyses were carried out:

[0078] Among them, Tables 7 and 8 are the main process parameters in this example; Table 9 is the pulp index in this example.

[0079] Table 7

[0080]

[0081] Table 8

[0082]

[0083] Table 9

[0084]

[0085] As can be seen from Tables 7, 8, and 9 above, the total amount of alkali used in the third pulping of rubber wood is 60 kg, and the total amount of hydrogen peroxide used is 97 kg. The total amount of alkali used in the third pulping of poplar wood is 60 kg, and the total amount of hydrogen peroxide used is 98 kg. As can be seen from the above table, under the conditions of Example 3, the pulp index of rubber wood is as follows: pulp whiteness 76.66% ISO, freeness 457 ml, bulk density 3.10 cm 3 / g, tear index 2.95 mN.m 2 / g, breaking length 2.62 Km, tensile index 25.98 Nm / g, internal bond strength 87.8 J / m 2 , stiffness 330 mN, fiber bundle content 0.09%. As can be seen from the above table, under the conditions of Example 3, the pulp index of poplar wood is as follows: pulp whiteness 75.49% ISO, freeness 460 ml, bulk density 2.64 cm 3 / g, tear index 2.71 mN.m2 / g, breaking length 2.80 Km, tensile index 26.05 Nm / g, internal bond strength 81.9 J / ㎡, stiffness 344 mN, fiber bundle content 0.01%.

[0086] In summary, as can be seen from the above data, after replacing the traditional P-RC APMP pulping raw materials (such as eucalyptus and poplar) with rubber wood in the embodiments of the present invention, under the condition that the total alkali consumption is 60 kg and other chemicals are basically the same, the whiteness of rubber wood is 1.17% ISO higher than that of poplar. The bulk, internal bond and tear index of the pulp made from rubber wood are relatively high. The tensile index and stiffness of poplar are slightly higher but are basically the same as those of rubber wood, indicating that rubber wood can be completely used in industrial production and rubber wood has a higher bulk and can show better performance in high-bulk paper grades.

[0087] As can be seen from the above embodiments, the present invention creatively proposes a PRC-APMP pulping process using rubber wood as the raw material. This process can produce chemical mechanical pulp with high whiteness, high bulk and high strength, which not only helps to increase the proportion of chemical mechanical pulp used in cultural paper, but also can effectively reduce production costs and save wood resources, and has significant application value.

[0088] Some embodiments of the present invention have been described and their efficacy evaluated above. It should be understood that the present invention is not limited to the above specific embodiments. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into equivalent embodiments with equivalent changes, which does not affect the essence of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A pulping process for rubber wood PRC-APMP, characterized in that, It includes the following steps: S1. Wash the rubber wood chips and then perform pre-steaming until they are softened to obtain the pre-treated chips; S2. Subject the pre-treated chips to single-stage extrusion tearing, single-stage chemical liquor pre-impregnation, single-stage chemical reaction, two-stage extrusion tearing, two-stage chemical liquor pre-impregnation, two-stage chemical reaction, and high-concentration pulping to obtain the rough pulp; S3. After separating the pulp from the gas, add chemical liquor to the rough pulp and perform high-concentration bleaching to obtain the bleached pulp; S4. After performing low-concentration pulping on the bleached pulp, add a composite dispersant, and then perform screening, washing, and concentration to obtain the finished pulp.

2. The PRC-APMP pulping process of rubber wood according to claim 1, wherein In step S1, the density of the rubber wood chips is 0.1 to 0.4 g / cm 3 ; and / or, the size of the rubber wood chips has a length of 15 to 30 mm and a thickness of 3 to 5 mm; And / or, the material level of the pre-steaming is ≥70%, and the temperature is 80 - 85°C.

3. The PRC-APMP pulping process for rubber wood according to claim 1, wherein, In step S2, the speed of the single-stage extrusion tearing is 50 - 100 rpm, the torque is 70 - 120 kN·m, and the power is 500 - 1000 kW; the speed of the two-stage extrusion tearing is 50 - 100 rpm, the torque is 70 - 120 kN·m, and the power is 500 - 1000 kW.

4. The PRC-APMP pulping process of rubber wood according to claim 1, characterized in that, In step S2, in the chemical liquor for the single-stage chemical liquor pre-impregnation, the mass of sodium hydroxide relative to the dry wood chips is 0.5 - 1.0%, the mass of hydrogen peroxide relative to the dry wood chips is 1.0 - 1.5%, the mass of sodium silicate relative to the dry wood chips is 0.1 - 1.0%, and the mass of DTPA relative to the dry wood chips is 0.1 - 1.5%; the impregnation time of the single-stage chemical liquor pre-impregnation is 10 - 15 min; And / or, in the chemical liquor for the two-stage chemical liquor pre-impregnation, the mass of sodium hydroxide relative to the dry wood chips is 1.0 - 2.0%, the mass of hydrogen peroxide relative to the dry wood chips is 2.0 - 5.0%, the mass of sodium silicate relative to the dry wood chips is 0.1 - 1.0%, the mass of DTPA relative to the dry wood chips is 0.5 - 2.0%, and the mass of the auxiliary agent relative to the dry wood chips is 0.1 - 0.5%; the impregnation time of the two-stage chemical liquor pre-impregnation is 10 - 15 min.

5. The PRC-APMP pulping process of rubber wood according to claim 1, characterized in that, In step S2, the reaction temperature of the single-stage chemical reaction is 90°C - 100°C, the reaction time is 20 - 30 min, the reaction concentration is 20% - 30%, and the material level in the reaction bin is greater than 60%; And / or, the reaction temperature of the two-stage chemical reaction is 90°C - 100°C, the reaction time is 20 - 30 min, the reaction concentration is 20% - 30%, and the material level in the reaction bin is greater than 60%.

6. The PRC-APMP pulping process of rubber wood according to claim 1, characterized in that, In step S2, the pulping concentration of the high-concentration pulping is 30 - 40%, the pulping power is 4.0 - 8.0 MW; the unit energy consumption of pulping is 300 - 600 kWh / ADMT.

7. The PRC-APMP pulping process of rubber wood according to claim 1, characterized in that, In step S3, the addition amount of the chemical liquor is: the mass of sodium hydroxide relative to the dry pulp is 2.0 - 5.0%, the mass of hydrogen peroxide relative to the dry pulp is 4.0 - 10.0%, the mass of sodium silicate relative to the dry pulp is 0.5 - 1.0%, the mass of DTPA relative to the dry wood chips is 0.5 - 2.0%, and the mass of the auxiliary agent relative to the dry wood chips is 0.1 - 0.5%; And / or, the bleaching time of the high-concentration bleaching is 70 - 90 minutes, the temperature is 70 - 90°C, and the bleaching concentration is 25 - 30%.

8. The PRC-APMP pulping process of rubber wood according to claim 1, characterized in that, In step S4, the pulping consistency of the low-consistency pulping is 4-6%, the pulping power is 1000-1500 KW; the unit energy consumption of pulping is 50-100 kWh / ADMT.

9. The PRC-APMP pulping process for rubberwood according to claim 1, characterized in that, In step S4, the composite dispersant is a mixture of PAAS and AEO-9, wherein the weight ratio of PAAS to AEO-9 is 2:1; the dosage of the composite dispersant is 3 kg / absolute dry ton; And / or, the consistency of the finished pulp is 25-35%.

10. A finished pulp, characterized in that, It is made by the rubberwood PRC-APMP pulping process according to any one of claims 1-9; the brightness of the finished pulp is ≥75% ISO.

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