阅读说明：本技术 一种天然乳胶管的制备方法 (Preparation method of natural latex tube ) 是由 李志锋 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种天然乳胶管的制备方法,采用循环浸渍法,包括以下步骤：1.混合分散体制备；2.硫化胶乳制备；3.热敏胶乳制备；4.硅胶模芯牵引至乳胶管循环浸渍机浸渍热敏胶乳；5.脱模、沥滤和预干燥；6.表面处理和终干燥,得到循环浸渍天然乳胶管。本发明应用循环浸渍法,制备内径≥6mm、外径≥12mm的大规格天然乳胶管,与传统的热敏压出法相比,生产效率提高13倍以上,质量水平稳定；通过增加浸渍次数可以制备得到传统热敏压出法难以制备的管壁厚度≥5.5mm的厚壁天然乳胶管,且质量水平稳定。本发明可操作性强,可实现工业化生产。(The invention discloses a preparation method of a natural latex tube, which adopts a circulating impregnation method and comprises the following steps: 1. preparing a mixed dispersion; 2. preparing vulcanized latex; 3. preparing heat-sensitive latex; 4. the silica gel mold core is drawn to a latex tube circulating dipping machine to dip the thermosensitive latex; 5. demolding, leaching and predrying; 6. surface treatment and final drying to obtain the circular dipped natural latex tube. The invention applies the circular dipping method to prepare the large-size natural latex tube with the inner diameter of more than or equal to 6mm and the outer diameter of more than or equal to 12mm, compared with the traditional thermo-sensitive extrusion method, the production efficiency is improved by more than 13 times, and the quality level is stable; the thick-wall natural latex tube with the tube wall thickness of more than or equal to 5.5mm, which is difficult to prepare by the traditional thermosensitive extrusion method, can be prepared by increasing the dipping times, and has stable quality level. The invention has strong operability and can realize industrial production.)

1. The preparation method of the natural latex tube is characterized in that a circulating impregnation method is adopted, and the method comprises the following steps:

the method comprises the following steps: preparation of Mixed Dispersion

Preparing an aqueous mixed dispersion from a rubber vulcanizing agent, an active agent, an accelerator, a dispersing agent, casein, ammonia water and water, and filtering for later use;

step two: preparation of vulcanized latex

Mixing the natural latex, the stabilizer and the reinforcing agent with the mixed dispersoid obtained in the step one and water, heating and vulcanizing;

step three: preparation of Heat-sensitive latex

Mixing the vulcanized latex obtained in the step two with a thermosensitive agent, an antioxidant dispersion liquid and water, uniformly stirring and filtering for later use;

step four: dipping heat-sensitive latex

Selecting a silica gel mold core with a corresponding diameter according to the outer diameter of the latex tube to be prepared, cleaning and connecting the silica gel mold core, then drawing the silica gel mold core into the thermosensitive latex obtained in the step three, circularly dipping the thermosensitive latex and drying the thermosensitive latex until the outer diameter of the latex tube reaches a required value;

step five: demoulding, leaching and predrying

Extracting the silica gel mold core to obtain a semi-finished product of the demoulded latex tube, and pre-drying after leaching;

step six: surface treatment and final drying

And D, performing surface chlorination on the semi-finished product of the pre-dried latex tube obtained in the fifth step, and performing final drying after cleaning to obtain the natural latex tube.

2. The method of claim 1, wherein the step one of preparing the mixed dispersion comprises the steps of:

mixing a rubber vulcanizing agent, an activating agent and an accelerating agent with a dispersing agent, casein, ammonia water and water according to the following weight ratio, so that the solid content of the obtained mixed dispersoid is 50 wt%, mixing, grinding and filtering;

3. the method of claim 1, wherein the rubber vulcanizing agent in step one is sulfur, the activator is zinc oxide, the accelerator is TMTD, the dispersant is 10 wt% NF, casein is 10 wt% aqueous solution, and ammonia is 11.5 wt% aqueous solution.

4. The method of claim 1, wherein the vulcanized latex of step two comprises the following steps:

firstly adding a stabilizer into the natural concentrated latex in a stirring state according to the following weight ratio, adding a reinforcing agent, a mixed dispersion and water when the temperature of the latex rises to 35-40 ℃ to enable the solid content after mixing to be 55 wt%, heating to 53-57 ℃, preserving the temperature for 70-90 min, cooling to room temperature, standing and curing for 1-2 days;

5. the method of claim 1 wherein in step two the stabilizer is 20 wt% peregal O and the strengthening agent is a mixture of 45 wt% MG49 day A latex, 28 wt% epoxidized natural latex and 50 wt% aqueous calcium carbonate; the epoxidation degree of the epoxidized natural latex is 25%, and the particle size of the 50 wt% aqueous calcium carbonate is 0.5-2.0 μm.

6. The method of claim 1, wherein the heat-sensitive latex of step three comprises the following steps:

respectively adding the antioxidant dispersion liquid, the heat sensitive agent and water into vulcanized latex in the following weight ratio under the stirring state to ensure that the solid content after mixing is 50 wt%, stirring, filtering and standing;

7. the method for preparing natural latex tube as claimed in claim 1, wherein said thermosensitive agent in step three is 25 wt% polypropylene glycol with molecular weight of 800, and said dispersion of antioxidant is 50 wt% dispersion of antioxidant CPL.

8. The method of claim 1, wherein when the silica gel core is selected in the fourth step, the shrinkage of the inner diameter of the latex tube after final drying is 6-8%; the temperature of the thermosensitive latex is 16-18 ℃; the drying temperature is as follows: 150-165 ℃, single drying time: 70-75 s, single dipping time: 12-15 s.

9. The method for preparing natural latex tube as claimed in claim 1, wherein the leaching time in step five is 12-50h, the pre-drying temperature is 70-90 ℃, and the pre-drying time is 3-5 h.

10. The method for preparing the natural latex tube according to claim 1, wherein the surface chlorination treatment in the sixth step comprises the following specific steps: soaking with solution with effective chlorine content of 0.25-0.45g/L for 5-7 min; the final drying temperature is 70-90 ℃, and the time is 1-2 h.

Technical Field

The invention belongs to the technical field of natural latex tubes, and particularly relates to a preparation method of a natural latex tube.

Background

The natural latex tube is used for medical assistance, experimental instrument connection, fitness equipment assembly and the like, and the specification of the natural latex tube is represented by inner diameter (mm) x outer diameter (mm), the inner diameter range is 1.5-9 mm, and the outer diameter range is 3-20 mm. The traditional thermosensitive extrusion method for preparing the natural latex tube is applied to the present day from 1930, but the thermosensitive extrusion method for preparing the large-size natural latex tube with the inner diameter of more than or equal to 6mm and the outer diameter of more than or equal to 12mm has the production efficiency of a decreasing trend and the appearance quality defect of an increasing trend along with the increase of the inner diameter and the outer diameter, and the thermosensitive extrusion method is difficult to prepare the thick-wall natural latex tube with the tube wall thickness of more than or equal to 5.5mm, such as 7mm multiplied by 18 mm. The large-size or thick-wall natural latex tube has excellent elasticity and stretching multiple and excellent 300% stretching performance, is more suitable for assembling and using strength training type fitness equipment, has large market demand, but the traditional thermosensitive extrusion method cannot meet the market demand easily. Therefore, from the viewpoint of meeting the market demand and increasing the economic benefits of enterprises, the research and development of a preparation method of a large-size or thick-wall natural latex tube with high production efficiency and stable quality level is urgently needed.

Disclosure of Invention

The invention aims to provide a preparation method of a natural latex tube, which aims to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: a method for preparing a natural latex tube comprises the following steps:

the method comprises the following steps: preparation of Mixed Dispersion

Preparing an aqueous mixed dispersion from a rubber vulcanizing agent, an activator, an accelerator, a dispersant, casein, ammonia water and water, and filtering for later use.

Further, the rubber vulcanizing agent is in a powdery state.

Further, the preparation method of the mixed dispersion comprises the following steps:

mixing a rubber vulcanizing agent, an activating agent and an accelerating agent with a dispersing agent, casein, ammonia water and water according to the following weight ratio, so that the solid content of the obtained mixed dispersoid is 50 wt%, mixing, grinding and filtering;

further, the rubber vulcanizing agent is sulfur, the activator is zinc oxide, the accelerator is an accelerator TMTD, the dispersing agent is 10 wt% NF, the casein is 10 wt% aqueous solution, and the ammonia water is 11.5 wt% aqueous solution.

Further, a ball mill is used for grinding, and a stainless steel screen is used for filtering.

Furthermore, the rotation speed of the ball mill is 80rpm, the grinding time is 60h, and the aperture of the stainless steel screen is 0.28 mm.

Step two: preparation of vulcanized latex

And (3) stirring and mixing the natural latex, the stabilizer and the reinforcing agent with the mixed dispersoid obtained in the step one and water, heating and vulcanizing.

Further, the preparation method of the vulcanized latex comprises the following steps:

firstly adding a stabilizer into natural latex in a stirring state according to the following weight ratio, adding a reinforcing agent, a mixed dispersion and water when the latex temperature rises to 40 ℃ to enable the solid content after mixing to be 55 wt%, heating to 53-57 ℃, preserving the temperature for 70-90 min, cooling to room temperature, standing and curing for 1-2 days;

further, the stabilizer is 20 wt% of peregal O, and the reinforcing agent is a mixture of 45 wt% of MG49 skatesole latex, 28 wt% of epoxidized natural latex and 50 wt% of aqueous calcium carbonate; the epoxidation degree of the epoxidized natural latex is 25%, and the particle size of the 50 wt% aqueous calcium carbonate is 0.5-2.0 μm.

Further, the reinforcing agent comprises 45 wt% of MG49 skyhook latex, 28 wt% of epoxidized natural rubber latex and 50 wt% of water-based calcium carbonate, and the weight ratio of the reinforcing agent is (11.1-17.8): (7.1-14.3): (14-20).

Further, the vulcanization degree reaches a chloroform value from two ends to three ends.

Step three: preparation of Heat-sensitive latex

And (4) mixing and stirring the vulcanized latex obtained in the step two with the thermosensitive agent, the antioxidant dispersion liquid and water uniformly, and filtering for later use.

Further, the preparation method of the heat-sensitive latex comprises the following steps:

respectively adding the antioxidant dispersion liquid, the heat sensitive agent and water into vulcanized latex in the following weight ratio under the stirring state to ensure that the solid content after mixing is 50 wt%, stirring, filtering and standing;

further, the thermosensitive agent is 25 wt% of polypropylene glycol with the molecular weight of 800, and the antioxidant dispersion liquid is 50 wt% of antioxidant CPL dispersion liquid.

Further, the 50% by weight antioxidant CPL dispersion is a rubber antioxidant.

The polypropylene glycol with the molecular weight of 800 is an organic heat-sensitive agent of natural latex, and has the advantages that: the thermosensitive latex has better thermosensitive property than inorganic thermosensitive agent, and the preparation efficiency of the circular dipping method is improved. Meanwhile, compared with the common organic heat-sensitive agent polyvinyl methyl ether, the method does not need to neutralize and remove ammonia from the concentrated latex by formaldehyde, and is beneficial to environmental protection, health of operators and simplification of the preparation process. The heat-sensitive latex prepared by the polypropylene glycol with the molecular weight of 800 maintains better stability when being stored for 2 days in an environment with the temperature of 28 ℃, and the heat-sensitive latex is solidified on the surface of a mould when meeting the heated mould in a dipping tank. In order to adapt to continuous circulating latex dipping, circulating cooling water is introduced through the interlayer of the dipping tank to control the temperature of the heat-sensitive latex to be 16-18 ℃.

Further, the stirring time is 30-60 min.

Further, stainless steel mesh with a pore size of 0.28mm was used for the filtration.

Furthermore, the parking time is 2-8 h.

Step four: dipping heat-sensitive latex

And D, selecting a silica gel mold core with a corresponding diameter according to the outer diameter of the latex tube to be prepared, cleaning and connecting the silica gel mold core, drawing the silica gel mold core into the thermosensitive latex obtained in the step three, circularly dipping the thermosensitive latex and drying the thermosensitive latex until the outer diameter of the latex tube reaches a required value.

Furthermore, when the silica gel mold core is selected, the shrinkage of the inner diameter of the dipped latex tube after final drying is 6-8 percent; the drying temperature is as follows: 150-165 ℃, single drying time: 70-75 s, single dipping time: 12-15 s.

Furthermore, the silica gel mold core be the solid circular silicone tube of high temperature resistant of different diameters, cut into 20 meters/strip and connect with the rubber, take out the silica gel mold core when conveniently drawing the patterns.

Further, the impregnation is carried out in a latex tube circulation impregnator.

Step five: demoulding, leaching and predrying

And extracting the silica gel mold core to obtain a semi-finished product of the demoulded latex tube, and pre-drying after leaching.

Further, after the outer diameter of the latex tube reaches a required value, the latex tube is cut at the joint of the silica gel core and sent to a special demolding water tank, high-pressure tap water is connected to one end of the latex tube, and the silica gel mold core is manually pulled out from the other end of the latex tube, so that a semi-finished product of the demolding latex tube is obtained.

Further, the leaching time is 12-50h, the pre-drying temperature is 70-90 ℃, and the time is 3-5 h.

Step six: surface treatment and final drying

And D, performing surface chlorination on the semi-finished product of the pre-dried latex tube obtained in the fifth step, and performing final drying after cleaning to obtain the natural latex tube.

Further, the specific surface chlorination treatment method comprises the following steps: soaking with solution with effective chlorine content of 0.25-0.45g/L for 5-7 min; the final drying temperature is 70-90 ℃, and the time is 1-2 h;

further, both pre-drying and final drying are carried out in a hot air circulation drying room.

The invention has the beneficial effects that:

1. the invention provides a preparation method of a natural latex tube, which adopts a circulating immersion method to prepare a large-size natural latex tube with an inner diameter of more than or equal to 6mm and an outer diameter of more than or equal to 12mm, improves the production efficiency by more than 13 times compared with the traditional thermosensitive extrusion method, and has stable quality level.

2. Natural latex tubes (such as 7mm multiplied by 18mm and the like) with the tube wall thickness of more than or equal to 5.5mm are difficult to prepare by a heat-sensitive extrusion method, and can be successfully prepared by increasing the dipping times by adopting a circulating dipping method, and the quality level is stable.

3. And (3) taking a silicone tube as a mold core, drying, circularly dipping the thermosensitive latex on a latex tube circulating dipping machine, and drying at a short time at a high temperature until the required diameter value of the latex tube is reached. The wet gel impregnated each time does not have layering because of no barrier components such as coagulator and the like, and is tightly combined after being dried. The method has the advantages that the silica gel mold core with the proper diameter is selected, the frequency of circularly dipping the heat-sensitive latex is controlled, various natural latex tubes with large specifications and tube wall thicknesses of more than or equal to 5.5mm can be prepared, and the diameter consistency is good.

4. By adding the reinforcing agent consisting of the mixture of MG49 Tianjia latex, epoxidized natural latex and water-based calcium carbonate into the vulcanized latex, the tensile strength of the large-size or thick-wall natural latex tube is improved by more than 30 percent, the tearing strength is improved by more than 50 percent, and the 300 percent constant elongation value is improved by more than 60 percent on the premise of not reducing the elongation at break, so that the large-size or thick-wall natural latex tube is more suitable for assembling strength training type fitness equipment.

5. The circulating dipping process is applied by combining the circulating dipping machine of the natural latex tube, the operability is strong, and the industrial production is realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below.

FIG. 1 is a flow chart of the preparation process of the present invention.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

In the following examples, in the second step, 61.5 wt% of the natural concentrated latex and the mixed dispersion are stirred and mixed in a latex vulcanizing tank, the latex vulcanizing tank is a sandwich type reaction tank with a stainless steel stirring paddle and an inner container, the sandwich layer can be heated by introducing hot water or cooled by introducing cold water, and the rotating speed of the stirring paddle is 40 rpm. The epoxidized natural latex employed in step two had an epoxidation level of 25%.

And in the fourth step, the dipping is carried out in a latex tube circulating dipping machine of a vertical type device with a drying box, a heat-sensitive latex dipping tank and a plurality of groups of traction pulleys, wherein the height of the vertical type device is about 4m, and the used latex tube automatic dipping machine is a vertical type device with a drying box, a heat-sensitive latex dipping tank and a plurality of groups of traction pulleys. 2 or even a plurality of latex tube circulating impregnators can be used in series after traction according to the requirement of latex tube impregnation. The back of the latex tube circulating impregnator is provided with a drying box with adjustable temperature, and the bottom of the drying box is provided with a thermosensitive latex impregnation tank. The silica gel mold core passes through a plurality of traction pulleys, runs from bottom to top from the front side of the latex tube circulating impregnator, turns to the back side through the traction pulley at the highest position, runs from top to bottom and enters the drying box. The running time of each time the silica gel mold core enters the drying oven and leaves the drying oven is single drying time. After the silica gel mold cores run away from the drying box, the silica gel mold cores are dragged into the thermosensitive latex dipping tank by a traction pulley in the dipping tank, and the time from the entering of the silica gel mold cores to the leaving of the liquid level of the thermosensitive latex is the single dipping time. The silica gel mold core dipped with the thermosensitive latex runs from bottom to top from the front side of the latex tube circulating dipping machine, then turns to the back side to run from top to bottom through the traction pulley at the highest position, enters the drying box for the 2 nd time, dips the thermosensitive latex for the 2 nd time after drying, and the process is repeated. And (5) circularly dipping the heat-sensitive latex and drying until the outer diameter of the latex tube reaches a required value, and stopping dipping the heat-sensitive latex.

The description will not be repeated below.