CN113954257A - Intermittent equidirectional vacuum mechanical premixing preparation method for aerospace ablation heat-proof chopped fiber/phenolic aldehyde premix - Google Patents
Intermittent equidirectional vacuum mechanical premixing preparation method for aerospace ablation heat-proof chopped fiber/phenolic aldehyde premix Download PDFInfo
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Abstract
The invention provides an intermittent equidirectional vacuum mechanical premixing preparation method of a space ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix. According to the invention, firstly, intermittent mechanical premixing is adopted, namely multi-cycle short-time kneading is adopted, so that the fibers can be completely soaked by resin, the uniformity of the premix can be ensured, and the problem that the fibers are damaged due to overlong kneading time can be avoided; secondly, mechanical premixing in the same direction is adopted to reduce the collision intensity and collision frequency of the molecules of the dispersion system and prevent phase separation, sedimentation, precipitation and the like; thirdly, vacuum mechanical premixing is adopted, and after multi-period kneading, dealcoholization treatment is carried out in a vacuum state, so that the gel content is ensured not to generate gradient change when the premix is aired. Compared with a manual premixing method, the intermittent equidirectional mechanical premixing method has the advantages that the number of operators is reduced by 71.4%; the uniformity of the resin content is superior to that of the manual premixing method; the mechanical property of the composite material is equivalent to that of the composite material obtained by mould pressing of the premix prepared by a manual premixing method; the premix has no glue content difference in the vertical direction.
Description
Technical Field
The invention belongs to the technical field of composite materials in new materials, and particularly relates to an intermittent equidirectional vacuum mechanical premixing preparation method for a space ablation heat-proof chopped fiber/phenolic aldehyde premix.
Background
The aerospace ablation heat-proof chopped fiber/phenolic aldehyde premix is an intermediate material of a aerospace craft heat protection composite material. The traditional aerospace ablation heat-proof chopped fiber/phenolic aldehyde premix production process is a manual premixing method. The manual premixing process has the defects of high labor intensity, low production efficiency, high labor cost, correlation between product quality and operator proficiency, large dispersion of resin content of the premix, gradient change of gel content in the vertical direction and the like.
Disclosure of Invention
The invention solves the technical problems that the manual premixing process for preparing the aerospace ablation heat-proof chopped fiber/phenolic aldehyde premix has the defects of high labor intensity, low production efficiency, high labor cost, correlation between product quality and operator proficiency, large dispersion of resin content of the premix, gradient change of gel content in the vertical direction and the like.
In order to solve the problems, the invention provides an intermittent equidirectional vacuum mechanical premixing preparation method of a space ablation heat-proof chopped fiber/phenolic aldehyde premix. The method for preparing the aerospace ablation heat-proof chopped fiber/phenolic aldehyde premix by adopting the intermittent equidirectional vacuum mechanical premixing method can avoid the problems. Compared with a manual premixing method, the intermittent equidirectional mechanical premixing method has the advantages that the number of operators is reduced by 71.4%, the production working hour of each unit of premix is reduced by 86.1%, and the production efficiency is improved by 7.2 times; the uniformity of the resin content of the premix prepared by the mechanical premixing method is superior to that of the resin content of the premix prepared by the manual premixing method; the mechanical property of the composite material obtained by mould pressing of the premix prepared by the mechanical premixing method and the manual premixing method is equivalent to that of the composite material; the premix prepared by the mechanical premixing method has no gel content difference in the vertical direction.
The intermittent equidirectional mechanical premixing preparation method of the aerospace ablation heat-proof chopped fiber/phenolic aldehyde premix is to prepare the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix by adopting a vacuum kneading machine through an intermittent equidirectional mechanical vacuum premixing preparation method of non-conductive chopped fibers, phenolic aldehyde, an auxiliary agent and the like.
Preferably, the net volume of the vacuum kneader is 300L, the power of a main motor is 18.5kW, the vacuum degree is-0.09 MPa, and the two-paddle speed ratio is 1: 1.42, fast and slow paddle speed 35.5/25.5 rpm. The stirring blades are sigma-shaped, are unfolded according to an Archimedes spiral line, are horizontally arranged in parallel, rotate in opposite directions during working and have different rotating speeds, and the spiral blades perform axial extrusion and radial extrusion on rotating materials; not only does high-speed extrusion, but also does low-speed extrusion; the squeezing movement and the separating movement are carried out.
Preferably, the chopped fibers are non-conductive fibers, have the length of (5-360) mm and comprise alkali-free glass fiber chopped yarns, high-silica chopped yarns, high-strength glass fiber chopped yarns, quartz chopped yarns and alumina chopped yarns.
Preferably, the phenolic aldehyde comprises ammonia phenolic aldehyde wet-process resin, magnesium phenolic aldehyde wet-process resin, barium phenolic aldehyde wet-process resin, boron-silicon phenolic aldehyde wet-process resin, epoxy modified phenolic aldehyde wet-process resin, benzoxazine wet-process resin, inorganic modified phenolic aldehyde wet-process resin and nano modified phenolic aldehyde wet-process resin.
Preferably, the auxiliary agent is alcohol, acetone, butanone, petroleum ether or ethyl acetate.
Preferably, in the aspect of raw material proportioning, the mass ratio of the phenolic aldehyde to the fibers is (90-250): 100, and the adding amount of the solvent is 10-35% of the mass of the phenolic aldehyde.
Preferably, the prepared premix should have uniform color without the defects of resin accumulation, non-wetting of dry yarn, and the like. The three performance indexes of the premix are respectively required to be resin content (33-55)%, volatile matter content less than or equal to 10% and insoluble resin content (3-20)%.
Preferably, the amount of the mixture is preferably (60 to 80) kg, and the ratio of the volume of the direct stirring to the total volume of the cylinder is (52 to 65)%.
Preferably, the feeding mode is that yarn feeding is carried out in three times. Firstly, uniformly putting 15kg of chopped fibers into a kneader, and positively rotating for 5-60 seconds; uniformly adding 15kg of chopped fibers, and rotating forwards for 5-60 seconds; finally, the remaining 15kg of chopped fibers are uniformly added, and the cover is closed. The material is evenly fed into the cylinder for many times, the feeding amount is not increased suddenly or large blocks are not cut, the fiber is broken mechanically, the material strength is reduced seriously, and the serious damage of the structural strength of the equipment and even the phenomenon of 'pulp clamping' caused by the uneven extrusion impact between the stirring paddle and the stirring cylinder are also prevented.
Preferably, the mechanical premixing process is a batch co-directional vacuum. Since the longer the kneading time, the greater the loss of strength of the fibers, and the too short a time, the resin and the fibers are not uniformly mixed, the kneading time should be shortened as much as possible while ensuring uniform impregnation of the fibers with the resin. Firstly, intermittent mechanical premixing is adopted, namely multi-cycle short-time kneading and middle standing are carried out for a long time, so that fibers can be completely soaked by resin, the uniformity of the premix can be ensured, and the problems of fiber damage and premix strength reduction caused by overlong kneading time can be solved; secondly, mechanical premixing in the same direction is adopted to reduce the collision intensity and collision frequency of the molecules of the dispersion system, prevent phase separation, sedimentation, precipitation and the like, uniformly disperse the materials in the shortest time and reduce kneading time; thirdly, vacuum mechanical premixing is adopted, namely after multi-period kneading, dealcoholization treatment is carried out in a vacuum state, and the condition that the gel content does not change in a gradient manner when the premix is taken out of a pot and aired is ensured.
TABLE 1 intermittent same-direction mechanical premixing
Compared with the prior art, the invention has the following beneficial effects:
1. compared with a manual premixing method, the intermittent equidirectional vacuum mechanical premixing method has the advantages that the number of operators is reduced by 71.4%, the production working hour of each unit of premix is reduced by 86.1%, and the production efficiency is improved by 7.2 times;
2. the resin content uniformity of the premix prepared by the intermittent equidirectional vacuum mechanical premixing method is superior to that of the manual premixing method;
3. the mechanical properties of the composite material obtained by the intermittent equidirectional vacuum mechanical premixing method and the premix die pressing prepared by the manual premixing method are equivalent;
4. the premix prepared by the intermittent equidirectional vacuum mechanical premixing method has no difference of gel content in the vertical direction;
5. the intermittent equidirectional vacuum mechanical premixing method is one of the core innovation points of the invention. Since the longer the kneading time, the greater the loss of strength of the fibers, and the too short a time, the resin and the fibers are not uniformly mixed, the kneading time should be shortened as much as possible while ensuring uniform impregnation of the fibers with the resin. Firstly, intermittent mechanical premixing is adopted, namely multi-cycle short-time kneading and middle standing are carried out for a long time, so that fibers can be completely soaked by resin, the uniformity of the premix can be ensured, and the problems of fiber damage and premix strength reduction caused by overlong kneading time can be solved; secondly, mechanical premixing in the same direction is adopted to reduce the collision intensity and collision frequency of the molecules of the dispersion system, prevent phase separation, sedimentation, precipitation and the like, uniformly disperse the materials in the shortest time and reduce kneading time; thirdly, vacuum mechanical premixing is adopted, namely after multi-period kneading, dealcoholization treatment is carried out in a vacuum state, and the condition that the gel content does not change in a gradient manner when the premix is taken out of a pot and aired is ensured.
Drawings
FIG. 1 is a schematic view of a vacuum kneader for preparing a high silica chopped strand/ammonia phenolic premix according to example 1 of the present invention;
FIG. 2 is a pictorial representation of the high silica chopped fiber/ammonia phenolic premix obtained in example 1 of the present invention;
FIG. 3 is a macro topography of a high silica chopped strand/ammonia phenolic composite obtained in example 1 of the present invention;
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.
Example 1
The high silica short fiber/ammonia phenolic premix and the composite material thereof provided by the embodiment are prepared from the raw materials of high silica short fibers, ammonia phenolic and absolute ethyl alcohol.
The preparation method of the high silica chopped fiber/ammonia phenolic aldehyde premix and the composite material thereof described in the embodiment specifically comprises the following steps:
1. filtering the resin by using a (100-200) mesh copper or stainless steel filter screen;
2. the cutting length of the high silica fiber is 24mm, and the high silica fiber is heated in an oven at the temperature of (120 +/-5) DEG for 4 hours;
3. weighing (35.5-37.5) kg of ammonia phenolic resin, pouring into a kneader, adding (23-25) L of absolute ethyl alcohol, and rotating positively for 1-2 min to uniformly mix the resin solution;
4. weighing (45 +/-0.1) kg of high silica glass fiber chopped yarns;
5. yarn feeding is carried out for three times. Firstly, uniformly throwing 15kg of high silica glass fiber chopped yarns into each part of a kneader, and positively rotating for 30 s; then 15kg of yarn is evenly added, and the yarn is positively rotated for 30 s; finally, uniformly adding the rest 15kg of yarns, and closing the cover;
6. intermittent equidirectional vacuum mechanical premixing;
TABLE 1 intermittent same-direction mechanical premixing
7. Tearing and loosening the mixed material twice by using a tearing and loosening machine;
8. uniformly laying the torn and loosened materials on a clean net grate;
9. airing at room temperature for 2 h;
drying the material for 10min at 10.80 ℃;
11. testing three indexes, bagging and sealing after the indexes are qualified, and starting the high-silica chopped fiber/ammonia phenolic premix after three days;
and (3) filling a mold at 12.80 ℃, closing the mold, adding 10MPa of contact pressure, heating to 100 ℃ in 50min, adding 40MPa of full pressure, deflating for 3 times before pressurizing, heating to 150 ℃ at the speed of 5 ℃/10min, calculating the heat preservation time according to the thickness of the product for 2min/mm, naturally cooling, and demolding at the temperature of less than 60 ℃ to obtain the high-silica chopped fiber/ammonia phenolic aldehyde composite material.
By detecting the high-silica chopped fiber/ammonia phenolic aldehyde premix obtained in the embodiment, the resin content is 41.69%, the volatile matter content is 2.93%, and the insoluble resin content is 6.60%. The obtained high-silica chopped fiber/ammonia phenolic aldehyde composite material is detected, and the tensile strength of the dense 8-shaped die is 51.4MPa, and the compressive strength is 117 MPa.
Example 2
The raw materials for preparing the high silica chopped fiber/magnesium phenolic premix and the composite material thereof comprise high silica chopped fiber, magnesium phenolic resin and absolute ethyl alcohol.
The preparation methods of the high silica chopped fiber/magnesium phenolic premix and the composite material thereof described in the embodiment are as follows:
1. filtering the resin by using a (100-200) mesh copper or stainless steel filter screen;
2. the cutting length of the high silica fiber is 24mm, and the high silica fiber is heated in an oven at the temperature of (120 +/-5) DEG for 4 hours;
3. weighing (44-47) kg of magnesium phenolic resin, pouring into a kneader, adding (19-22) L of absolute ethyl alcohol, and rotating positively for 1-2 min to uniformly mix the resin solution;
4. weighing (45 +/-0.1) kg of high silica glass fiber chopped yarns;
5. yarn feeding is carried out for three times. Firstly, uniformly throwing 15kg of high silica glass fiber chopped yarns into each part of a kneader, and positively rotating for 30 s; then 15kg of yarn is evenly added, and the yarn is positively rotated for 30 s; finally, uniformly adding the rest 15kg of yarns, and closing the cover;
6. intermittent equidirectional vacuum mechanical premixing;
TABLE 2 intermittent same-direction mechanical premixing
7. Tearing and loosening the mixed material twice by using a tearing and loosening machine;
8. uniformly laying the torn and loosened materials on a clean net grate;
9. airing at room temperature for 2 h;
drying the material for 10min at 10.80 ℃;
11. testing three indexes, bagging and sealing after the indexes are qualified, and starting the high-silica chopped fiber/magnesium phenolic premix after three days;
and (3) filling a die at 12.80 ℃, closing the die, adding 10MPa of contact pressure, heating to 100 ℃ in 50min, adding 40MPa of full pressure, deflating for 3 times before pressurizing, heating to 150 ℃ at the speed of 5 ℃/10min, calculating the heat preservation time according to the thickness of the product for 2min/mm, naturally cooling, and demoulding at the temperature of less than 60 ℃ to obtain the high-silica chopped fiber/magnesium phenolic composite material.
Comparative example 1
The high silica chopped fiber/ammonia phenolic aldehyde premix described in this example is prepared by a manual premixing method, and the premix proportion and the composite material molding process are the same as those in example 1.
Comparative example 2
The high silica chopped fiber/magnesium phenolic aldehyde premix in the embodiment is prepared by a manual premixing method, and the proportion of the premix and the molding process of the composite material are the same as those in the embodiment 2.
Premix and composite Performance testing
The resin content, volatile content, and insoluble resin content of the premixes obtained in the above examples were measured, and the results of the measurements are shown in tables 3 and 4, which indicates that the uniformity of the premixes prepared by the mechanical premixing method is superior to that of the manual premixing method; comparing the production man-hours of the premixes, as shown in table 5, it can be seen that the number of operators is reduced by 71.4% in the mechanical premixing method compared with the manual premixing method, the production man-hour per unit of the premixes is reduced by 86.1%, and the production efficiency is improved by 7.2 times; the tensile strength and compressive strength of the 8-shaped mold of the composite material were measured, and the results are shown in table 6, which shows that the mechanical properties of the composite material obtained by molding the premix prepared by the mechanical premixing method are equivalent to those of the composite material obtained by molding the premix prepared by the manual premixing method.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
TABLE 3 preparation of premix by mechanical premixing and manual premixing
TABLE 4 coefficient of variation of resin content in the mechanically and manually premixed premixes
TABLE 5 comparison of working hours for mechanical and manual premixing processes
TABLE 6 mechanical Properties of the composites
Claims (10)
1. An intermittent equidirectional vacuum mechanical premixing preparation method of a space ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix is characterized by comprising the following steps of:
the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix is prepared by adopting a vacuum kneader to prepare non-conductive chopped fiber, phenolic aldehyde, an auxiliary agent and the like through an intermittent equidirectional mechanical vacuum premixing preparation method.
2. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
the net volume of the vacuum kneading machine is 300L, the power of a main motor is 18.5kW, the vacuum degree is-0.09 MPa, and the two-paddle speed ratio is 1: 1.42, fast and slow paddle speed 35.5/25.5 rpm. The stirring blades are sigma-shaped, are unfolded according to an Archimedes spiral line, are horizontally arranged in parallel, rotate in opposite directions during working and have different rotating speeds, and the spiral blades perform axial extrusion and radial extrusion on rotating materials; not only does high-speed extrusion, but also does low-speed extrusion; the squeezing movement and the separating movement are carried out.
3. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
the chopped fiber is non-conductive fiber, has the length of 5-360 mm and comprises alkali-free glass fiber chopped yarn, high-silica chopped yarn, high-strength glass fiber chopped yarn, quartz chopped yarn and alumina chopped yarn.
4. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
the phenolic comprises ammonia phenolic wet-process resin, magnesium phenolic wet-process resin, barium phenolic wet-process resin, boron-silicon phenolic wet-process resin, epoxy modified phenolic wet-process resin, benzoxazine wet-process resin, inorganic modified phenolic wet-process resin and nano modified phenolic wet-process resin.
5. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
the auxiliary agent is alcohol, acetone, butanone, petroleum ether or ethyl acetate.
6. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
in the aspect of raw material proportion, the mass ratio of the phenolic aldehyde to the fiber is (90-250): 100, and the adding amount of the solvent is 10-35% of the mass of the phenolic aldehyde.
7. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
the prepared premix has uniform color, and has no defects of resin accumulation, non-wetting dry yarn and the like. The three performance indexes of the premix are respectively required to be resin content (33-55)%, volatile matter content less than or equal to 10% and insoluble resin content (3-20)%.
8. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
the amount of the mixed material is preferably (60 to 80) kg, and the ratio of the volume of the direct stirring to the total volume of the cylinder is (52 to 65)%.
9. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
the feeding mode is to feed yarns in three times. Firstly, uniformly putting 15kg of chopped fibers into a kneader, and positively rotating for 5-60 seconds; uniformly adding 15kg of chopped fibers, and rotating forwards for 5-60 seconds; finally, the remaining 15kg of chopped fibers are uniformly added, and the cover is closed. The material is evenly fed into the cylinder for many times, the feeding amount is not increased suddenly or large blocks are not cut, the fiber is broken mechanically, the material strength is reduced seriously, and the serious damage of the structural strength of the equipment and even the phenomenon of 'pulp clamping' caused by the uneven extrusion impact between the stirring paddle and the stirring cylinder are also prevented.
10. The intermittent equidirectional vacuum mechanical premixing preparation method of the aerospace ablation heat-proof non-conductive chopped fiber/phenolic aldehyde premix as claimed in claim 1, wherein the method comprises the following steps:
intermittent equidirectional vacuum mechanical premixing method. Since the longer the kneading time, the greater the loss of strength of the fibers, and the too short a time, the resin and the fibers are not uniformly mixed, the kneading time should be shortened as much as possible while ensuring uniform impregnation of the fibers with the resin. Firstly, intermittent mechanical premixing is adopted, namely multi-cycle short-time kneading and middle standing are carried out for a long time, so that fibers can be completely soaked by resin, the uniformity of the premix can be ensured, and the problems of fiber damage and premix strength reduction caused by overlong kneading time can be solved; secondly, mechanical premixing in the same direction is adopted to reduce the collision intensity and collision frequency of the molecules of the dispersion system, prevent phase separation, sedimentation, precipitation and the like, uniformly disperse the materials in the shortest time and reduce kneading time; thirdly, vacuum mechanical premixing is adopted, namely after multi-period kneading, dealcoholization treatment is carried out in a vacuum state, and the condition that the gel content does not change in a gradient manner when the premix is taken out of a pot and aired is ensured.
TABLE 1 intermittent same-direction mechanical premixing
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115489043A (en) * | 2022-11-14 | 2022-12-20 | 北京玻钢院复合材料有限公司 | Intermittent vacuum mechanical premixing method for resin-based premix |
| CN116038933A (en) * | 2023-01-09 | 2023-05-02 | 东莞广丰兴塑胶有限公司 | Preparation process and preparation device of special efficient antibacterial master batch for eva |
-
2021
- 2021-09-30 CN CN202111161484.4A patent/CN113954257A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115489043A (en) * | 2022-11-14 | 2022-12-20 | 北京玻钢院复合材料有限公司 | Intermittent vacuum mechanical premixing method for resin-based premix |
| CN116038933A (en) * | 2023-01-09 | 2023-05-02 | 东莞广丰兴塑胶有限公司 | Preparation process and preparation device of special efficient antibacterial master batch for eva |
| CN116038933B (en) * | 2023-01-09 | 2024-05-17 | 东莞广丰兴塑胶有限公司 | Preparation process and preparation device of special efficient antibacterial master batch for eva |
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