阅读说明：本技术 一种菠萝全叶抗菌纤维及其制备方法 (Pineapple whole-leaf antibacterial fiber and preparation method thereof ) 是由 陈港 钱杨杨 刘义军 王淳玉 于 2021-10-07 设计创作，主要内容包括：本发明涉及一种菠萝全叶抗菌纤维及其制备方法,通过将菠萝叶经原料预处理、高浓疏解或高浓磨浆、低浓打浆、筛浆、脱水干燥或抄片成纸干燥制备而成。本发明结合造纸业常用的纯机械制浆法,制备工艺简便、成本低廉、绿色环保、易于实现产业化,且纤维得率大于7%,纤维长度介于0.5-5.8 mm,成功解决了传统化学处理法提取菠萝叶纤维过程存在的成本高、污染大、得率低等难题。本发明所得纤维易于制成纯菠萝叶纤维纸,纸张抗菌性好,对大肠杆菌、金黄色葡萄球菌以及白色念珠菌的抑菌率大于99%。此外,本发明工艺所得纤维制成的纯菠萝叶纤维纸张物理性能良好,抗张强度高、柔韧性好,利于菠萝叶纤维在食品抗菌包装、医用抗菌纸、生活抗菌纸等方面的推广。(The invention relates to a pineapple whole-leaf antibacterial fiber and a preparation method thereof. The method combines a pure mechanical pulping method commonly used in the paper making industry, has simple and convenient preparation process, low cost, environmental protection and easy realization of industrialization, the fiber yield is more than 7 percent, the fiber length is between 0.5 and 5.8 mm, and the problems of high cost, large pollution, low yield and the like in the process of extracting the pineapple leaf fiber by the traditional chemical treatment method are successfully solved. The fiber obtained by the invention is easy to prepare pure pineapple leaf fiber paper, the antibacterial property of the paper is good, and the bacteriostasis rate of the paper to escherichia coli, staphylococcus aureus and candida albicans is more than 99%. In addition, the pure pineapple leaf fiber paper made of the fibers obtained by the process has good physical properties, high tensile strength and good flexibility, and is beneficial to popularization of the pineapple leaf fibers in the aspects of food antibacterial packaging, medical antibacterial paper, life antibacterial paper and the like.)

1. The pineapple whole-leaf antibacterial fiber and the preparation method thereof are characterized by comprising the following preparation steps:

(1) pretreatment of raw materials: waste pineapple leaves are used as raw materials, and fresh pineapple leaves and dry pineapple leaves are sorted, cut short and cleaned to obtain clean pineapple leaf blocks;

(2) high-concentration defibering or high-concentration pulping: adding water into fresh pineapple leaf blocks and softened dry pineapple leaf blocks to adjust to a certain concentration, and placing in a fiber fluffer or a common disc grinder for fluffing or grinding;

(3) pulping at low concentration: placing the pineapple leaf pulp subjected to high-concentration defibering or pulping into a pulping machine for low-concentration pulping;

(4) screening pulp: screening and collecting the pulped pineapple leaf pulp in a pulp screening machine such as a flat plate slotted screen, a circular hole screen and the like;

(5) dewatering and drying or sheet making and paper drying: placing the screened and collected pineapple pulp into a dryer for drying to obtain a pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net, and drying to obtain the pure pineapple leaf fiber paper.

2. The method of claim 1, wherein: the chopped pineapple leaf blocks in the step (1) are strips with the length of 5 cm.

3. The method of claim 1, wherein: softening the leaf epidermis by adding a softening agent after cleaning the dried pineapple leaves in the step (2); the softener is selected from one or more of cellulase, pectinase, xylanase, mannanase and polygalacturonase.

4. The method of claim 1, wherein: the concentration of the high-concentration defibering material in the step (2) is 15-25%, and the defibering time is 30-120 min; the disc grinding gap of the disc grinder is 0.1-1.5 mm, and the grinding concentration is 15-25%.

5. The method of claim 1, wherein: 3-grade gradient pulping is adopted in the low-consistency pulping in the step (3), the pulping concentration is 1.5-10%, the 1 st-grade pulping load is 0-1 kg, and the pulping time is 30-90 min; the grade 2 beating load is 1.5-3 kg, 20-60 min; the beating load of the 3 rd level is 3.5-5 kg, 5-20 min.

6. The method of claim 1, wherein: the seam width of the flat-plate seam screen in the step (4) is 0.1-0.5 mm; the diameter of the sieve pore of the round-hole sieve is 5-12 mm.

7. The method of claim 1, wherein: the dehydration mode in the step (5) is one or two of centrifugal dehydration and screw extrusion dehydration;

the drying method comprises hot air drying, vacuum drying, freeze drying, microwave drying, vacuum microwave drying and the like.

8. The method of claim 1, wherein: and (5) drying the formed paper sheet forming net in the step (5), namely drying the obtained wet paper sheet by a squeezing dryer to prepare the pure pineapple leaf fiber paper.

9. The pineapple whole-leaf antibacterial fiber prepared by the preparation method according to any one of claims 1 to 8, characterized in that: the fiber yield is more than 7 percent, the fiber length is between 0.5 and 5.8 mm, and the beating degree is between 15 and 70 DEG SR; pure pineapple leaf fiber paper for gram of escherichia coli, staphylococcus aureus, candida albicans and the likeThe bacteriostasis rates of the positive bacteria and the negative bacteria are both more than 99 percent; the pure pineapple leaf fiber paper has good physical properties, and the gram weight is about 50-200 g/m²Tightness of 0.2-0.48 g/cm³A tensile index of 2.45 to 5.35 (N.m/g) and a burst index of 0.68 to 2.12 (Kpa.m)²Per g) and a tear index of 2.66 to 5.25 (mN.m)²(g) and the folding endurance is 10-100 times.

Technical Field

The invention relates to a pineapple whole-leaf antibacterial fiber and a preparation method thereof, belonging to the technical field of high-valued utilization of biomass.

Technical Field

The waste recycling and rural biomass energy are one of the main contents of the national long-term development strategy research, and the problem of high-efficiency utilization of agricultural resources is a long-standing problem in modern agricultural development in China. The pineapple is an important tropical and subtropical fruit in China, the total planting area of the pineapple in China breaks through 100 ten thousand acres, and the pineapple plays an important role in promoting the industry happiness of local villages and peasants to get rich. The pineapple is mainly composed of pineapple leaves and pineapple fruits, wherein the pineapple leaves are basically in a waste state, about 1000 million tons of pineapple wastes can be generated in China every year according to statistics, and if the pineapple leaves are ground and returned to the field, soil acidification, combustion or landfill and environmental pollution are easily caused. Researches show that the waste pineapple leaves are rich in cellulose, and natural bioactive compounds or antibacterial ingredients such as triterpenes, amides, phenylpropanoids, antioxidants and the like (periodicals: research progress of chemical ingredients and biological activity of pineapple leaves; and shallow talk about research of antibacterial substances of the pineapple leaf fibers), and can be widely used as industrial raw materials such as food, paper making, textiles, antibacterial agents and the like, so that the waste pineapple leaves have very important development value.

At present, the antibacterial fiber is mainly prepared by adding materials with antibacterial property such as nano silver, copper carbon and the like. For example, Wanxing industry Co Ltd, Anhui, prepares an antibacterial material for mask antibiosis by adding nano silver and copper carbon into edible starch (patent CN 202010288513.2). The Hunan Yixiang clothing Co Ltd combines tetrabutyl titanate with nano-silver sol, and then obtains an antibacterial material through acid catalysis, thus obtaining the antibacterial fiber material for clothing (patent CN 202010359891.5). The research of hemp of Chinese academy of agricultural sciences, so that the silver ion solution is a silver source precursor, the plant extract is used as a biological reducing agent, after the hemp fiber absorbs silver ions, the industrial hemp flower and leaf plant extract is used for reducing the silver ions in situ and growing nano silver particles on the surface or in the fiber, and the nano antibacterial hemp fiber after reaction realizes high-efficiency, quick and lasting antibacterial performance and washability (patent CN 201910402270.8). Anxin nanometer science and technology (group) company Limited uses nanometer silver particles as an antibacterial agent, and cotton, flax and blended fibers as carriers to prepare plant fibers with antibacterial effect (patent CN 200580043733.2). The antibacterial composite membrane is prepared by compounding pineapple leaf fiber powder and a graphene-zinc nanocomposite by taizhou li wei environmental protection technology limited (patent CN 108484953A). Although the antibacterial material prepared by the method has excellent antibacterial performance, the antibacterial material prepared by adding chemical substances has the defects of complex process, high cost, environmental pollution and the like.

The extraction method of the pineapple leaf fiber mainly comprises a water immersion method, a chemical method, a biological enzyme method, a mechanical method and the like at present. The tension and the like adopt a hand-feeding type scutcher to extract the pineapple leaf fibers, the fiber extraction rate is 90-93%, the impurity content is 1-5%, and the extraction yield is 40 kg/h, but the problems of high quality requirement on pineapple leaves, high labor intensity, low pineapple leaf fiber yield and the like exist (a paper: research on extraction of pineapple leaf fibers and process equipment). Li Ming Fu and so on adopt the temperature to soak the pineapple leaves in the mobile or closed fermentation tank of 30 ℃, then the residual leaf residue is scraped manually, obtain the pineapple leaf fiber, but the production time is long, the occupied area is large, the labor intensity is large, the extraction rate is low, the soaking wastewater pollutes the environment, the cost is high (thesis: dynamic and development strategy of research of the pineapple leaf fiber). Liu Enping and the like adopt a pectinase method to prepare the pineapple leaf fiber meeting the requirements of textile technology, the linear density of the pineapple leaf fiber is 1.88 tex, the breaking strength is 34.29 cN/tex, and the breaking elongation is 2.69 percent, but the pineapple leaf fiber prepared by the method has the problems of poor product stability, specificity, high production cost and the like (thesis: the enzymatic degumming technology of the pineapple leaf fiber). Zhang Hui Min et al studied manual scutching, scutching + steam flash explosion, retting + steam flash explosion or steam flash explosion + retting pretreatment to prepare pineapple leaf fiber, its bacteriostatic rate to colibacillus, staphylococcus aureus, Candida albicans is 64-87%, 71-93%, 74-81% respectively, although the pineapple leaf fiber prepared by this study meets the standard in bacteriostatic efficiency, the surface colloid of fiber obtained is unevenly distributed, the labour intensity is large, the requirement for raw materials is high (the paper: research of antibacterial property and mechanism of pineapple leaf fiber).

Therefore, the method for extracting the pineapple whole-leaf antibacterial fiber is green, environment-friendly, low in cost and simple and convenient in process, and is beneficial to solving the problem of soil acidification caused by crushing and returning pineapple leaves, and solving the problems of high cost, high pollution, low utilization rate and the like in the extraction process of the pineapple leaf fiber.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a method which is environment-friendly, low in cost and simple and convenient in process for preparing the pineapple whole-leaf antibacterial fiber.

In order to achieve the above purpose, the present invention is realized by the following means:

the invention provides a pineapple whole-leaf antibacterial fiber, which is selected from fresh pineapple leaves or dried pineapple leaves or a mixture thereof.

Most preferably, the pineapple leaves are preferably fresh pineapple leaves.

The second aspect of the invention provides a preparation method of pineapple whole-leaf antibacterial fiber, which comprises the following steps:

(1) pretreatment of raw materials: the method is characterized in that waste pineapple leaves are used as raw materials, and fresh pineapple leaves and dry pineapple leaves are sorted, cut short and cleaned to obtain clean pineapple leaf blocks.

(2) High-concentration defibering or high-concentration pulping: adding water into fresh pineapple leaf blocks and softened dry pineapple leaf blocks to adjust to a certain concentration, and placing in a fiber fluffer or a common disc grinder for fluffing or grinding;

(3) pulping at low concentration: placing the pineapple leaf pulp subjected to high-concentration defibering or pulping into a pulping machine for low-concentration pulping;

(4) screening pulp: screening and collecting the pulped pineapple leaf pulp in a pulp screening machine such as a flat plate slotted screen, a circular hole screen and the like;

(5) dewatering and drying or sheet making and paper drying: placing the screened and collected pineapple pulp into a dryer for drying to obtain a pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net, and drying to obtain the pure pineapple leaf fiber paper.

Preferably, the chopped pineapple leaf pieces of step (1) are 5 cm long strips;

preferably, the dried pineapple leaves in the step (2) are washed and then treated with a softener to soften the leaf epidermis; the softener is selected from one or more of cellulase, pectinase, xylanase, mannanase and polygalacturonase; the addition amount of the softener is preferably 0.05-0.1% of the dry pineapple leaf mass.

Most preferably, the concentration of the high-concentration defibering material in the step (2) is 15-25%, and the defibering time is preferably 30-90 min; the disc mill has disc mill gap of 0.1-1.5 mm, preferably 0.3-0.9, and refining concentration of 15-25%.

Preferably, the low-consistency beating in the step (3) adopts 3-grade gradient beating, the beating concentration is 1.5-10%, the beating degree is preferably 30-65 DEG SR, the 1 st-grade beating load is 0-1 kg, and the 30-90 min is carried out; the grade 2 beating load is 1.5-3 kg, 20-60 min; the beating load of the 3 rd level is 3.5-5 kg, 5-20 min.

Preferably, the slot width of the flat plate slot screen in the step (4) is 0.1-0.5 mm; the diameter of the sieve pore of the round-hole sieve is 5-12 mm.

Preferably, the dehydration mode in the step (5) is one or two of centrifugal dehydration and screw extrusion dehydration. The drying method comprises hot air drying, vacuum drying, freeze drying, microwave drying, vacuum microwave drying and the like;

preferably, the hot air drying temperature in the step (5) is 60-105 ℃; the vacuum drying temperature is 50-80 ℃, and the vacuum degree is-0.08 to-0.1 MPa; the freeze drying temperature is-10 to-40 ℃, and the vacuum degree is-0.08 to-0.1 MPa; the microwave drying temperature is 80-105 ℃; the vacuum microwave drying temperature is 50-80 ℃.

Preferably, the drying after the forming of the paper forming net in the step (5) refers to drying by a press dryer, wherein the drying temperature of the press dryer is controlled to be 90-120 ℃, and the drying time is 15-30 min.

The pineapple whole-leaf antibacterial fiber prepared by the steps is characterized in that: the fiber yield is more than 7 percent, the fiber length is between 0.5 and 5.8 mm, and the beating degree is between 15 and 70 DEG SR; the pure pineapple leaf fiber paper has the bacteriostasis rate of more than 99% on gram-positive bacteria and gram-negative bacteria such as escherichia coli, staphylococcus aureus, candida albicans and the like; the pure pineapple leaf fiber paper has good physical properties, and the gram weight is about 50-200 g/m²Tightness of 0.2-0.48 g/cm³A tensile index of 2.45 to 5.35 (N.m/g) and a burst index of 0.68 to 2.12 (Kpa.m)²Per g) and a tear index of 2.66 to 5.25 (mN.m)²(g) and the folding endurance is 10-100 times.

Compared with the prior art, the invention has the following beneficial effects:

(1) the method combines a pure mechanical pulping method commonly used in the paper making industry, has simple and convenient preparation process, low cost, environmental protection and easy realization of industrialization, the fiber yield is more than 7 percent, the fiber length is between 0.5 and 5.8 mm, and the problems of high cost, large pollution, low yield and the like in the process of extracting the pineapple leaf fiber by the traditional chemical treatment method are successfully solved.

(2) The fiber obtained by the process is easy to prepare pure pineapple leaf fiber paper, the antibacterial property of the paper is good, the bacteriostatic rate of escherichia coli, staphylococcus aureus and candida albicans is more than 99%, a pure mechanical pulping method has the advantages of retaining natural antibacterial components such as triterpenes, amides and phenylpropanoids in whole pineapple leaves and bioactive compounds such as antioxidants, and the damage of the chemical pulping process to the functional groups and the structures of the natural antibacterial components or the bioactive compounds is effectively avoided.

(3) The pure pineapple leaf fiber paper made of the fibers obtained by the process has good physical properties, high tensile strength and good flexibility, and is beneficial to popularization of the pineapple leaf fibers in the aspects of food antibacterial packaging, medical antibacterial paper, life antibacterial paper and the like.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present invention is further illustrated by the following specific examples.

Example 1

The preparation method of the pineapple whole-leaf antibacterial fiber comprises the following steps:

(1) pretreatment of raw materials: taking waste fresh pineapple leaves as a raw material, cutting the fresh pineapple leaves into strips with the length of 5 cm, and placing the strips in a cleaning machine to clean soil and other impurities;

(2) high concentration defibering: adding water into fresh pineapple leaf blocks to adjust the concentration to 25%, and then placing the pineapple leaf blocks in a fiber fluffer for high-concentration fluffing for 60 min;

(3) pulping at low concentration: placing the pineapple leaf pulp subjected to high-concentration defibering into a pulping machine for low-concentration pulping; 3-grade gradient pulping is adopted in low-consistency pulping, the pulping concentration is 10%, the 1 st-grade pulping load is 1 kg, and the pulping time is 90 min; the beating load of the 2 nd level is 3 kg, 60 min; the beating load of the 3 rd stage is 5 kg and 20 min.

(4) Screening pulp: screening the pineapple leaf pulp subjected to low-concentration pulping in a flat plate slotted screen pulp screening machine with the slot width of 0.35 mm, collecting pulp, and discarding the pulp;

(5) dewatering and drying or sheet making and paper drying: dehydrating the screened and collected pineapple pulp by a centrifugal machine, and then drying the pineapple pulp in a hot air dryer at 80 ℃ to obtain pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net according to a certain concentration, and drying in a squeezing dryer at 105 ℃ for 20 min to obtain the pure pineapple leaf fiber paper.

The pineapple whole-leaf antibacterial fiber obtained through the steps has the fiber yield of 8.4%, the fiber length of 0.5-2.8 mm and the fiber beating degree of 67.5 DEG SR; the obtained fiber is made into pure pineapple leaf paper, the bacteriostasis rate of the pure pineapple leaf paper to escherichia coli is 99.4%, the bacteriostasis rate of staphylococcus aureus is 99.8%, and the bacteriostasis rate of candida albicans is 99.2%; the pure pineapple leaf fiber paper has good physical properties and the gram weight is about 120 g/m²Tightness 0.48 g/cm³Tensile index of 4.99 (N.m/g) and burst index of 2.03 (Kpa.m)²In terms of/g) and a tear index of 5.15 (mN.m)²(g) and the folding endurance is 40-80 times.

Example 2

The preparation method of the pineapple whole-leaf antibacterial fiber comprises the following steps:

(1) pretreatment of raw materials: taking waste fresh pineapple leaves as a raw material, cutting the fresh pineapple leaves into strips with the length of 5 cm, and placing the strips in a cleaning machine to clean soil and other impurities;

(2) high concentration defibering: adding water into fresh pineapple leaf blocks to adjust the concentration to 20%, and then placing the pineapple leaf blocks in a fiber fluffer for high-concentration fluffing for 80 min;

(3) pulping at low concentration: placing the pineapple leaf pulp subjected to high-concentration defibering into a pulping machine for low-concentration pulping; 3-grade gradient pulping is adopted in low-consistency pulping, the pulping concentration is 10%, the 1 st-grade pulping load is 1 kg, and the pulping time is 50 min; the beating load of the 2 nd level is 3 kg, 30 min; the beating load of the 3 rd stage is 5 kg and 10 min.

(4) Screening pulp: screening the pineapple leaf pulp subjected to low-concentration pulping in a flat plate slotted screen pulp screening machine with the slot width of 0.35 mm, collecting pulp, and discarding the pulp;

(5) dewatering and drying or sheet making and paper drying: dehydrating the screened and collected pineapple pulp by a centrifugal machine, and then drying the pineapple pulp in a hot air dryer at 80 ℃ to obtain pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net according to a certain concentration, and drying in a press dryer at 115 ℃ for 10 min to obtain the pure pineapple leaf fiber paper.

The pineapple whole-leaf antibacterial fiber obtained through the steps has the fiber yield of 8.8%, the fiber length of 1.0-4.2 mm and the fiber beating degree of 47.5 DEG SR; the obtained fiber is made into pure pineapple leaf paper, the bacteriostasis rate of the pure pineapple leaf paper to escherichia coli is 99.1%, the bacteriostasis rate of staphylococcus aureus is 99.4%, and the bacteriostasis rate of candida albicans is 99.7%; the pure pineapple leaf fiber paper has good physical properties and the gram weight is about 120 g/m²Tightness 0.41 g/cm³Tensile index of 4.39 (N.m/g) and burst index of 1.87 (Kpa. m)²In terms of/g) and a tear index of 4.65 (mN.m)²(g) and the folding endurance is 20-60 times.

Embodiment 3

The preparation method of the pineapple whole-leaf antibacterial fiber comprises the following steps:

(1) pretreatment of raw materials: selecting fresh pineapple leaves and dry pineapple leaves by taking waste pineapple leaves as raw materials, and then respectively cutting the fresh pineapple leaves and the dry pineapple leaves into strips with the length of 5 cm; then respectively putting the chopped pineapple leaf blocks into a cleaning machine to clean soil and other impurities; meanwhile, adding pectinase and polygalacturonase with the proportion of 1:0.5 into the dried pineapple leaf blocks in a softening tank according to the addition amount of 0.05%, and soaking for 10 min to soften the skin of the dried pineapple leaves;

(2) high-concentration pulping: adding water into the fresh pineapple leaf blocks and the softened dry pineapple leaf blocks to adjust the concentration to 25%, and placing the fresh pineapple leaf blocks and the softened dry pineapple leaf blocks into a disc grinder to grind, wherein the gear clearance of the disc grinder is adjusted to be 0.35 mm;

(3) pulping at low concentration: placing the ground pineapple leaf pulp in a pulping machine for low-concentration pulping; 3-grade gradient pulping is adopted in low-consistency pulping, the pulping concentration is 10%, the 1 st-grade pulping load is 1 kg, and the pulping time is 50 min; the beating load of the 2 nd level is 3 kg, 30 min; the beating load of the 3 rd stage is 5 kg and 10 min.

(4) Screening pulp: screening the low-concentration pulped pineapple leaf pulp in a circular hole pulp screening machine with the diameter of a sieve pore of 10 mm, collecting pulp, and removing the pulp;

(5) dewatering and drying or sheet making and paper drying: dehydrating the screened and collected pineapple pulp by a centrifugal machine, and then drying in a freeze dryer at-40 ℃ to obtain pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net according to a certain concentration, and drying in a press dryer at 110 ℃ for 15 min to obtain the pure pineapple leaf fiber paper.

The pineapple whole-leaf antibacterial fiber obtained through the steps has the fiber yield of 7.3%, the fiber length of 0.6-3.3 mm and the fiber beating degree of 58 DEG SR; the obtained fiber is made into pure pineapple leaf paper, the bacteriostasis rate of the pure pineapple leaf paper to escherichia coli is 99.1%, the bacteriostasis rate of staphylococcus aureus is 99.5%, and the bacteriostasis rate of candida albicans is 99.4%; the pure pineapple leaf fiber paper has good physical properties and the gram weight is about 70 g/m²Tightness 0.45 g/cm³A tensile index of 5.35 (N.m/g) and a burst index of 2.12 (Kpa. m)²In terms of/g) and a tear index of 5.25 (mN.m)²(g) and the folding endurance is 40-100 times.

Comparative example 1

The preparation method of the pineapple whole-leaf antibacterial fiber comprises the following steps:

(1) pretreatment of raw materials: selecting fresh pineapple leaves and dry pineapple leaves by taking waste pineapple leaves as raw materials, and then respectively cutting the fresh pineapple leaves and the dry pineapple leaves into strips with the length of 5 cm; then respectively putting the chopped pineapple leaf blocks into a cleaning machine to clean soil and other impurities; meanwhile, adding pectinase and mannase with a ratio of 1:3 into the dried pineapple leaf blocks in a softening tank according to the addition amount of 0.1%, and soaking for 5 min to soften the skin of the dried pineapple leaves;

(2) high-concentration pulping: adding water into the fresh pineapple leaf blocks and the softened dry pineapple leaf blocks to adjust the concentration to 20%, and placing the mixture into a disc grinder to grind, wherein the gear clearance of the disc grinder is adjusted to be 0.7 mm;

(3) pulping at low concentration: placing the ground pineapple leaf pulp in a pulping machine for low-concentration pulping; the low-concentration pulping concentration is 3 percent, the pulping load is 1 kg, and the time is 50 min.

(4) Screening pulp: screening the low-concentration pulped pineapple leaf pulp in a circular hole pulp screening machine with the diameter of a sieve pore of 5 mm, collecting pulp, and removing the pulp;

(5) dewatering and drying or sheet making and paper drying: dehydrating the screened and collected pineapple pulp by a centrifugal machine, and then drying the pineapple pulp in a vacuum drying machine at 80 ℃ to obtain pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net according to a certain concentration, and drying in a press dryer at 115 ℃ for 10 min to obtain the pure pineapple leaf fiber paper.

The pineapple whole-leaf antibacterial fiber obtained through the steps has the fiber yield of 7.9%, the fiber length of 1.8-5.1 mm and the fiber beating degree of 24 DEG SR; the obtained fiber is made into pure pineapple leaf paper, the bacteriostasis rate of the pure pineapple leaf paper to escherichia coli is 99.3%, the bacteriostasis rate of staphylococcus aureus is 99.5%, and the bacteriostasis rate of candida albicans is 99.6%; the physical properties of the pure pineapple leaf fiber paper are general, and the gram weight is about 100 g/m²Tightness 0.23 g/cm³Tensile index of 3.05 (N.m/g) and burst index of 1.15 (Kpa. m)²In terms of/g) and a tear index of 3.11 (mN.m)²(g) and the folding endurance is 20-40 times.

Comparative example 2

The preparation method of the pineapple whole-leaf antibacterial fiber comprises the following steps:

(1) pretreatment of raw materials: selecting fresh pineapple leaves and dry pineapple leaves by taking waste pineapple leaves as raw materials, and then respectively cutting the fresh pineapple leaves and the dry pineapple leaves into strips with the length of 5 cm; then respectively putting the chopped pineapple leaf blocks into a cleaning machine to clean soil and other impurities; meanwhile, adding pectinase and mannase with a ratio of 1:3 into the dried pineapple leaf blocks in a softening tank according to the addition amount of 0.1%, and soaking for 5 min to soften the skin of the dried pineapple leaves;

(2) high-concentration pulping: adding water into the fresh pineapple leaf blocks and the softened dry pineapple leaf blocks to adjust the concentration to 20%, and placing the mixture into a disc grinder to grind, wherein the gear clearance of the disc grinder is adjusted to be 0.5 mm;

(3) pulping at low concentration: placing the ground pineapple leaf pulp in a pulping machine for 2-level gradient low-concentration pulping; the low-concentration pulping concentration is 5%, the grade 1 pulping load is 1 kg, and the time is 50 min; the beating load of the 2 nd stage is 2 kg, 20 min.

(4) Screening pulp: screening the low-concentration pulped pineapple leaf pulp in a circular hole pulp screening machine with the diameter of a sieve pore of 5 mm, collecting pulp, and removing the pulp;

(5) dewatering and drying or sheet making and paper drying: dehydrating the screened and collected pineapple pulp by a centrifugal machine, and then drying the pineapple pulp in a vacuum drying machine at 80 ℃ to obtain pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net according to a certain concentration, and drying in a squeezing dryer at 105 ℃ for 20 min to obtain the pure pineapple leaf fiber paper.

The pineapple whole-leaf antibacterial fiber obtained through the steps has the fiber yield of 7.7%, the fiber length of 1.4-4.8 mm and the fiber beating degree of 28 DEG SR; the obtained fiber is made into pure pineapple leaf paper, the bacteriostasis rate of the pure pineapple leaf paper to escherichia coli is 99.5%, the bacteriostasis rate of staphylococcus aureus is 99.6%, and the bacteriostasis rate of candida albicans is 99.4%; the physical properties of the pure pineapple leaf fiber paper are general, and the gram weight is about 70 g/m²Tightness 0.34 g/cm³A tensile index of 3.71 (N.m/g) and a burst index of 1.66 (Kpa. m)²In terms of/g) and a tear index of 3.88 (mN.m)²(g) and the folding endurance is 20-50 times.

Comparative example 3

The preparation method of the pineapple whole-leaf antibacterial fiber comprises the following steps:

(1) pretreatment of raw materials: selecting fresh pineapple leaves and dry pineapple leaves by taking waste pineapple leaves as raw materials, and then respectively cutting the fresh pineapple leaves and the dry pineapple leaves into strips with the length of 5 cm; then respectively putting the chopped pineapple leaf blocks into a cleaning machine to clean soil and other impurities; meanwhile, adding pectinase and mannase with a ratio of 1:3 into the dried pineapple leaf blocks in a softening tank according to the addition amount of 0.1%, and soaking for 5 min to soften the skin of the dried pineapple leaves;

(2) high concentration defibering: adding water into fresh pineapple leaf blocks to adjust the concentration to 25%, and then placing the pineapple leaf blocks in a fiber fluffer for high-concentration fluffing for 60 min;

(3) screening pulp: screening the ground pineapple leaf pulp in a circular hole pulp screening machine with the diameter of a sieve pore of 5 mm, collecting pulp, and removing the pulp;

(4) dewatering and drying or sheet making and paper drying: dehydrating the screened and collected pineapple pulp by a centrifugal machine, and then drying the pineapple pulp in a vacuum drying machine at 80 ℃ to obtain pineapple whole-leaf antibacterial fiber; or forming the screened and collected pineapple pulp through a paper sheet forming net according to a certain concentration, and drying in a squeezing dryer at 90 ℃ for 30 min to obtain the pure pineapple leaf fiber paper.

The pineapple whole-leaf antibacterial fiber obtained through the steps has the fiber yield of 9.2%, the fiber length of 2.0-5.8 mm and the fiber beating degree of 15.5 DEG SR; the obtained fiber is made into pure pineapple leaf paper, the bacteriostasis rate of the pure pineapple leaf paper to escherichia coli is 99.5%, the bacteriostasis rate of staphylococcus aureus is 99.4%, and the bacteriostasis rate of candida albicans is 99.8%; the physical property of the pure pineapple leaf fiber paper is poor, and the gram weight is about 100 g/m²Tightness 0.20 g/cm³A tensile index of 2.45 (N.m/g) and a burst index of 0.68 (Kpa.m)²In terms of/g) and a tear index of 2.66 (mN.m)²(g) and the folding endurance is 10-30 times.

Comparative example 4

According to Zhang Hui Min (research on antibacterial performance and mechanism of pineapple leaf fiber), pineapple leaves are pretreated by adopting a combined mode of steam flash explosion and retting, wherein the steam flash explosion pressure is 2 MPa, the pressure maintaining time is 3 min, the retting temperature is 37 ℃, and the retting is carried out for 5 days in natural pond water, so that the pineapple original hemp is obtained. Then adding 25 g/L sulfuric acid into the pineapple raw hemp according to the feed-liquid ratio of 1:50, soaking for 60 min at 55 ℃, then washing twice, adding 2% of alkali boiling solvent by mass of fiber, and treating for 120 min at 100 ℃, wherein the concentration of sodium hydroxide in the alkali boiling solvent is 15 g/L, the concentration of sodium sulfate is 4 g/L, and the concentration of sodium silicate is 3 g/L. Then washing with water for 1 time, adding 20 g/L sulfuric acid with a feed liquid ratio of 1:20, treating at 55 deg.C for 10 min, washing with water, neutralizing, washing with hot water, and oven drying to obtain pineapple leaf fiber. The bacteriostatic rates of the fiber on escherichia coli, staphylococcus aureus and candida albicans are 64-87%, 71-93% and 74-81% respectively.

TABLE 1 pineapple Whole-leaf antibacterial fiber length, yield, beating degree, and paper bacteriostatic and physical properties

In the table, a represents Escherichia coli; b represents staphylococcus aureus; c represents Candida albicans

It can be seen from the above table that the pineapple leaf fibers obtained by either high consistency refining or high consistency defibering, 3-grade gradient low consistency refining or 1-grade or 2-grade gradient refining, or even no refining, have excellent antibacterial properties after sheet making and paper making. Different defibering or pulping and gradient pulping processes only have important influence on the length and the pulping degree of fibers and physical indexes of the fibers after sheet making and paper making.

As can be seen from examples 1 to 3 and comparative examples 1 to 3, the length of the fiber has a large relationship with the degree of beating, and the higher the degree of beating of the fiber, the more easily the fiber is devillicate into brooming and is cut short, so the shorter the length of the resulting fiber; subsequently, the physical index after the fiber was formed into paper showed a tendency to increase and then decrease with the freeness, as in example 3, the freeness was 58.5 ° SR, and the tensile index, bursting index, tear index, and folding resistance of the pure pineapple leaf fiber paper were maximized. As the freeness increases to 67.5 SR, the physical indexes have a descending trend, which indicates that the freeness has an optimal interval.

In the above comparative examples 1 to 3, the 1-stage beating, the 2-stage gradient beating and the non-beating are respectively adopted, so that the beating degree is obviously smaller than that of the examples, the devillicate fibrillation degree of the fibers is lower, the bonding force between the fibers is lower, the physical property index of the paper after paper forming is poorer, and the most obvious embodiment is the reduction of the tightness, the tensile index, the burst index, the tearing index and the folding endurance.

Compared with the reported comparative example 4, the process disclosed by the invention is combined with a pure mechanical pulping process commonly used in papermaking, and has the advantages of simple and convenient preparation process, low cost, environmental protection and the like, and is easy to realize industrialization and the like. The extracted pineapple whole-leaf antibacterial fiber has higher bacteriostatic rate on escherichia coli, staphylococcus aureus and candida albicans after being formed into paper, which indicates that the steam flash explosion and chemical treatment method can damage the chemical composition and structure of the bacteriostatic component of the pineapple leaf fiber to a certain degree to cause the reduction of antibacterial performance, but the process has small damage degree on the functional group and structure of natural antibacterial components or bioactive compounds, and in addition, the development of the 3-level gradient pulping process is also favorable for obtaining paper with excellent physical properties, so the pineapple leaf fiber prepared by the process is favorable for popularization in the aspects of food antibacterial packaging, medical antibacterial paper, life antibacterial paper and the like.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art. It should be noted that the technical features not described in detail in the present invention can be implemented by any prior art in the field.