CN117284490A - PMI composite foam adapter and in-mold foaming manufacturing method thereof - Google Patents

Abstract

The invention discloses a PMI composite foam adapter and an in-mold foaming manufacturing method thereof, and relates to the technical field of emission equipment, wherein the PMI composite foam adapter comprises a foam body, a positioning and separating mechanism and an antifriction layer; the positioning and separating mechanism is inlaid in the foam body and is adhered and fixed with the foam to form a whole; the body is flame-retardant PMI composite foam, and the bottom of the body is adhered with the antifriction layer; an adhesive is arranged between the flame-retardant PMI composite foam and the antifriction layer to realize firm adhesion; the invention utilizes PMI composite foam as a main body to manufacture the adapter, provides high mechanical property, high heat resistance and long-term stability, and solves the problem that the PMI composite foam cannot be adhered by itself in the resin foaming process by using an adhesive with special chemical components and curing characteristics.

Description

PMI composite foam adapter and in-mold foaming manufacturing method thereof

Technical Field

The invention relates to the technical field of emission equipment, in particular to a PMI composite foam adapter and an in-mold foaming manufacturing method thereof.

Background

The adapter is used for matching the aircraft with the transmitting box (barrel), is an important component of the transmitting device, can play a plurality of roles of positioning, guiding, antifriction, vibration reduction and the like, and has an important influence on the transmitting reliability of the aircraft. The adapter must have necessary strength and rigidity, has compressive creep resistance under the condition of bearing ballast for a long time, and has good high temperature resistance and ablation resistance; in addition, it is required to be reliably connected to the aircraft and to be able to move in a synchronous and smooth manner in the tank with the aircraft; the adapter can be quickly separated from the aircraft when the aircraft is launched out of the box; the adapter has a reasonable price ratio on the premise of meeting the performance requirement.

The body material of the adapter is a load-bearing body; the adapter is generally provided with a metal positioning and separating mechanism for connecting and positioning on the aircraft and realizing quick detachment after the aircraft is out of the cylinder; the outer surface of the body is provided with an antifriction layer to reduce friction when the aircraft is loaded and launched.

The adapter of the prior art mainly adopts polyurethane foam material as a bearing main body, and has the following defects: first: the density and the mass of the polyurethane foam material are large, and after the launching box (barrel) falls down, impact and collision damage can be caused to ground equipment and adjacent launching boxes; second,: polyurethane foam materials have a temperature resistance of only 85 ℃, and limited flame retardance, and are difficult to resist high-temperature gas flow ablation during firing; third,: the polyurethane foam material has larger compressive creep under a long-term compression environment. In addition, other carrier adapter technologies suffer from a number of disadvantages, such as:

technology 1, CN105643947a is a missile adapter co-curing forming process, CN109895412a is an adapter forming process: polyurethane foam is used as a bearing main body and is manufactured by an in-mold foaming process. Firstly, presetting a metal piece and a surface antifriction material in a metal mold; measuring isocyanate, polyol, foaming agent, catalyst and the like, and stirring and mixing to obtain foamable mixed solution; pouring the mixed liquid material into a mould; closing a die; foaming at normal temperature or heating, and solidifying; cooling, opening and demoulding; deburring; an adapter is obtained. Problems: the polyurethane foam has low compressive strength; when the density is limited, the long-term compression creep amount is large; or the product is overweight on the premise of meeting the requirements of the specified compression strength and the compression creep property; the heat resistance is limited; furthermore, this technology does not describe a specific level of flame retardancy of the foam; such foams have limited flame retardancy, and in the best case, oxygen indices of only 30 to 32%; too much flame retardant can lead to deterioration of manufacturability and product performance.

Technology 2, CN113650225a polyurethane foam-PMI foam composite missile adapter and preparation method thereof: the PMI foam board is made of a main material and is manufactured by a process of pouring and foaming combination with polyurethane. Problems: the working procedures are more, the working time is long, and the working efficiency is low; the PMI foam needs to be cut and processed for many times, the material utilization rate is low, and the PMI foam board belongs to a high-cost material; this technology does not describe the flame retardancy level of polyurethane and PMI foams and does not achieve the high flame retardancy described in the present invention.

Technology 3, CN110749233a honeycomb structure adaptor, and manufacturing method and flow: manufacturing an adapter by taking a honeycomb material as a main body; at the end face of the honeycomb material, upper and lower panels were prepared with a fiber cloth prepreg, thereby forming an adapter body. Problems: the working procedure is complex, the work efficiency is low, and the yield is low; the autoclave compound technology is adopted, so that the manufacturing cost is high; only adapt to specific shapes and cannot adapt to complex product shapes.

Technology 4, CN101857656a expandable granules for producing polymethacrylimide foam and use, CN109467637B an acrylic foam which is heat-resistant in-mold foaming: methods of making foamable resin particles are described, as are methods of using the resin particles to foam in a mold to make heat resistant foam articles. Problems: the technology lacks the description of the technology required for preparing the adapter by selecting and bonding the surface layer materials, positioning and separating the structure and the fixing of the mechanism and the like; there is a lack of technical description regarding flame retardants required for preparing high flame retardant foams.

Technology 5, CN113831442a, a high cost performance flame retardant polymethacrylimide foam and its preparation method: disclosed is a flame-retardant polymethacrylimide foam and a preparation method thereof, which are suitable for preparing a flame-retardant PMI foam sheet material with high cost performance. Problems: the technology lacks descriptions of antifriction surface layer materials, positioning and separating mechanisms and other technologies required by the preparation of the adapter; lack of technical description of the invention for foaming in a mould to obtain a composite foam article; the flame retardant effect of the technology can only reach 30-32% of oxygen index under the best condition, and cannot reach the high flame retardance of more than 45% of oxygen index.

Technology 6, CN103923337B polymethacrylimide composite foam wave absorbing material: PMI syntactic foam wave absorbing materials and methods of making the same are described. Problems: the technology lacks descriptions of antifriction surface layer materials, positioning and separating mechanisms and other technologies required by the preparation of the adapter; lack of description of the flame retardancy of the foam and the route to it as described in the present invention.

In order to solve the problems, we provide a PMI composite foam adapter and an in-mold foaming manufacturing method thereof.

Disclosure of Invention

The invention aims to provide a PMI composite foam adapter and an in-mold foaming manufacturing method thereof, which are used for solving the problems in the background technology.

In order to achieve the above purpose, the present invention provides the following technical solutions:

a PMI composite foam adapter comprises a foam body, a positioning and separating mechanism and an antifriction layer;

the positioning and separating mechanism is inlaid in the foam body and is adhered and fixed with the foam to form a whole;

the foam body is flame-retardant PMI composite foam, and the bottom of the foam body is adhered to the antifriction layer;

and an adhesive is arranged between the flame-retardant PMI composite foam and the antifriction layer to realize firm adhesion.

As a further scheme of the invention: the antifriction layer is a polytetrafluoroethylene film subjected to chemical treatment.

As still further aspects of the invention: the positioning and separating mechanism comprises: the aircraft comprises a base, a cover plate, a spring and a pin shaft, wherein the base is fixedly connected with the cover plate through a screw, the spring is arranged in the base, the bottom of the pin shaft is propped against the spring, and the cover plate outwards penetrates through a connecting hole for being inserted into an aircraft shell.

Another object of the present invention is to provide a method for producing PMI syntactic foam adaptor by in-mold foaming, comprising the steps of:

step one: preparing foamable PMI resin particles with high cost performance;

step two: mixing the resin particles with an adhesive and a flame retardant to adhere a layer of adhesive mixture to the surfaces of the particles;

step three: placing foamable resin particles with adhesive mixture attached on the surface in a female mold of a foaming mold, and closing the mold;

step four: preferably, the mould is put into a curing furnace to be heated according to a program, the foamable resin particles expand and foam in the mould, the material fills the mould cavity, the PMI foam undergoes cyclization crosslinking reaction under a high-temperature environment, and meanwhile, the adhesive undergoes curing reaction, so that the foam particles are mutually bonded to form a whole;

step five: cooling the mould, opening the mould, demoulding, taking out the adapter blank, and trimming burrs of the adapter blank;

step six: the metal separation mechanism base is bonded and fixed at the position of a reserved hole in the PMI foam body formed by the die, and after the adhesive is solidified, a spring, a pin shaft and a cover plate are installed;

step seven: the cut antifriction layer is adhered to the PMI foam body, and is fixed through a vacuum bag, and the adapter is obtained after adhesion and solidification.

Still further aspects are as follows: the PMI resin particle preparation process in the step one comprises the following steps:

step one: the preparation method comprises the following steps of: methacrylic acid: 20 to 150 parts of methacrylonitrile: 10 to 80 parts of acrylonitrile: 5 to 80 parts of a third monomer: 0.1 to 6 parts of an initiator: 0.04 to 10 parts of a cross-linking agent: 0.02 to 5 parts of foaming agent: 0.5 to 25 parts of a flame retardant: 5 to 25 parts of other auxiliary agents: 0.9 to 20 parts of other auxiliary agents including, but not limited to, one or more combinations of retarder, nucleating agent, dispersant, mold release agent, heat resistant agent, antioxidant;

step two: uniformly mixing the component materials metered in the first step to obtain a raw material mixed solution;

step three: pouring the raw material mixed solution into a mould with a plurality of small cavities with diameters of 1-15 mm; sealing the die; the mold is placed in a water bath of 30 ℃ to 50 ℃ for polymerization for 10 to 60 hours, then in a water bath of 50 ℃ to 70 ℃ for polymerization for 4 to 40 hours, then in an oven of 70 ℃ to 120 ℃ for polymerization for 5 to 20 hours, the mold is cooled, and the foamable copolymer resin particles are obtained after demolding.

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

the invention uses PMI composite foam as main body to manufacture the adapter, provides high mechanical property, high heat resistance and long-term stability, uses adhesive with special chemical component and solidifying characteristic, solves the problem that the PMI composite foam can not be adhered by itself in the resin foaming process, contains high-efficiency flame retardant with special component, and has high flame retardant property far superior to PMI body flame retardant foam, uses closed mold foaming technology to manufacture the adapter, avoids the work efficiency reduction and material loss caused by the adhesion and processing of foam plates, coats the inner cavity of a metal mold and the surface possibly contacting materials at high temperature, solves the problem of adhering mold of products, prepares raw material formula of foamable resin particles, contains part of low-cost raw material monomers, and contains special flame retardant, so that the foam particle body has high cost performance and certain flame retardant property.

Wherein the present invention is distinguished from conventional foam adapters:

1. the mechanical properties are excellent: the PMI foam has excellent mechanical properties, and is remarkably superior to polyurethane foam. The aircraft has high compression strength, strong bearing capacity and small long-term compression creep, so that the aircraft is positioned in the box accurately for a long time; or have a significantly lower weight than polyurethane foam with equivalent pressure resistance.

2. Excellent heat resistance: is obviously superior to the heat resistance of polyurethane foam, and the heat resistance and the flame retardance are combined, so that the polyurethane foam is suitable for the high-temperature combustion gas flow ablation environment.

3. Excellent flame retardant property: foam particles with bulk flame retardance, combined with an inter-particle adhesive with high flame retardance, can obtain an oxygen index of more than 45%, and are remarkably superior to the conventional flame-retardant PMI foam or flame-retardant polyurethane foam; the performance is combined with heat resistance, so that the product is more suitable for the high-temperature combustion gas flow ablation environment.

4. Cost effective foamable resin: the preparation of the foamable resin partially uses low-cost raw material monomer acrylonitrile, and compared with methacrylonitrile, the raw material cost is obviously reduced.

5. Work efficiency is improved: obtaining a foam product by a mould forming method; comprises a reasonably designed antifriction surface layer material positioning mode. Compared with the mode of preparing the adapter by using the PMI foam plate, namely the modes of drying, cutting, bonding, processing and pasting the fabric, the invention simplifies the process flow and improves the work efficiency.

6. The material utilization rate is high: avoiding the waste of materials caused by the mode of preparing the adapter by machining the PMI foam board.

7. The equipment and the operation cost are low: the foaming, curing and forming of the product can be realized by using a heating oven or a hot press, an autoclave is not used, and the equipment and the operation cost are low.

8. A skin of closed cell foam: the PMI composite foam product obtained by closed-die foaming is provided with a closed-cell skin layer, so that the surface open-cell skin layer caused by machining the foam product is avoided, and the PMI composite foam product has better appearance, strength and dampproof effect.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Fig. 2 is a schematic structural view of a positioning and separating mechanism in the present invention.

FIG. 3 is a schematic view of a partial explosion of a foam molding die according to the present invention.

Wherein: foam body 1, antifriction layer 2, location separating mechanism 3, apron 31, round pin axle 32, base 33, spring 34, apron 41, mould bottom plate and end plate 42, curb plate one 43, curb plate two 44.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1 to 3, the PMI syntactic foam adaptor provided by the invention includes: the foam body 1 and the positioning and separating mechanism 3, the antifriction layer 2; the positioning and separating mechanism 3 is arranged on the foam body 1; the foam body 1 is flame-retardant PMI composite foam; an adhesive is arranged between the foam body 1 and the antifriction layer 2 to realize firm bonding.

Further, the antifriction layer is a polytetrafluoroethylene film subjected to chemical activation treatment.

Further, the positioning and separating mechanism is fixedly connected to the foam body in an embedded and bonded mode, and the foam body is used for bearing the weight load and the inertial force load of the aircraft, keeping the structural rigidity and ensuring the positioning of the aircraft in the box; the density of the foam body is between 100 and 400kg/m 3.

Further, the positioning and separating mechanism 3 includes: cover plate 31, base 33, pin 32, and spring 34; the cover plate 31 is mounted on the base 33; the spring 34 is installed inside the base 33, and the positioning and separating mechanism 3 further includes: the pin shaft 32 and the fixing screw; the pin 32 can be inserted into a connection hole of the aircraft shell; the cover plate 31 is connected with the base 33 through a fixing screw, and the base 33 of the positioning and separating mechanism 3 is embedded in the middle of the body 1 and firmly bonded; the pin 32 is inserted into the connection hole of the aircraft shell; when the adapter and the aircraft are in the launch bin (canister), the spring 34 is compressed; when the aircraft and the adapter are taken out of the box, the elastic force of the spring 34 enables the adapter to be separated from the aircraft, the pin shaft 32 is pulled out of the aircraft, and the adapter is separated from the aircraft and falls under the combined action of aerodynamic force, gravity and spring force.

The in-mold foaming molding method of the adapter comprises the following steps:

step one: foaming mold: designing and manufacturing a rigid mould for the foaming forming adapter; preferably the mold material is metal, more preferably the mold material is carbon steel; the foam molding die includes a female die and a cover plate 41; the female die is provided with a boss, and a hole for installing the separating mechanism base can be formed on the foam body of the adapter; the cover plate 41 can be covered on the female die;

preferably, the cover plate 41 and the female die 42 are tightly locked by bolts, and secondly, the cover plate and the female die can be tightly pressed by a hot press; the foam product can be taken out by opening the mould;

preferably, the female die is formed by combining a die bottom plate 42, an end plate 42, a side plate one 43 and a side plate two 44; the mold bottom plate and the end plate 42 are integrated, and the combination of the side plate I43 and the side plate II 44 and the mold bottom plate and the end plate 42 belongs to a detachable structure, and the mold bottom plate and the end plate are fixed through bolts;

preferably, all of the mold cavities and mold surfaces that may contact the material are coated with a fluoroplastic non-stick coating; the coating process comprises the steps of carrying out sand blasting treatment on a spraying surface of a die, then placing a die metal part in a heating furnace, heating to 400+/-35 ℃, taking out the die metal part, and spraying fluoroplastic powder; the mold part is again placed at 400 c + 35 c for 0.2 to 1 hour and then allowed to cool naturally to obtain the desired coating, the mold being reusable.

Step two: preparation of foamable resin particles:

a. the materials are measured according to the following weight portions:

methacrylic acid: 20 to 150 parts;

methacrylonitrile: 10 to 80 parts;

acrylonitrile: 5 to 80 parts;

third monomer: 0.1 to 6 parts;

and (3) an initiator: 0.04 to 10 parts;

crosslinking agent: 0.02 to 5 parts;

foaming agent: 0.5 to 25 parts;

flame retardant: 5 to 25 parts;

other auxiliary agents: 0.9 to 20 parts; other adjuvants include, but are not limited to, retarders, nucleating agents, dispersants, mold release agents, heat resistance agents, antioxidants, and the like;

b. uniformly mixing the component materials metered in the step a to obtain a raw material mixed solution;

c. preferably, the raw material mixture is poured into a mold having a plurality of small cavities with diameters of 1 to 15 mm inside; sealing the die; the mold is placed in a water bath of 30 ℃ to 50 ℃ for polymerization for 10 to 60 hours, then in a water bath of 50 ℃ to 70 ℃ for polymerization for 4 to 40 hours, then in an oven of 70 ℃ to 120 ℃ for polymerization for 5 to 20 hours, the mold is cooled, and the foamable copolymer resin particles are obtained after demolding.

Step three: preparing a foaming mold: cleaning a metal mold; positioning the antifriction surface layer material in the negative mold of the mold.

Step four: the materials are measured according to the following weight portions:

foamable resin particles: 20 to 95 parts;

an adhesive: 1 to 50 parts (resin, curing agent, catalyst, solvent);

flame retardant: 1 to 30 parts;

other auxiliary agents: 0.1 to 20 parts (containing staple fibers).

Step five: mixing of foamable materials: preheating the materials in the fourth step in a container at 30-150 ℃ for 10-30 minutes, and uniformly stirring to enable the surfaces of the particles to be adhered with a layer of adhesive mixture.

Step six: pouring the mixed materials obtained in the step five into a foaming mould; and closing the die and locking.

Step seven: foaming and curing: heating the foaming mould according to a program, preheating for 0.2 to 3 hours at 100 to 160 ℃, foaming and curing for 0.5 to 12 hours at 120 to 240 ℃, expanding and foaming the materials, filling the mould cavity, and completely curing; cooling and demoulding; and (4) deburring, namely trimming redundant antifriction layer materials at the edge to obtain the body of the adapter.

Step eight: bonding metal pieces: the body is provided with a mounting hole formed by a mould, and a metal base of the separating mechanism is embedded in the hole and bonded by glue, so that the metal base is firmly bonded with the foam body; and then a spring and a pin shaft are arranged in the base, and the cover plate is fixed by a screw while the spring is compressed.

Step nine: bonding an antifriction layer: and (3) adhering the antifriction layer to the adapter body obtained in the step (eight), fixing the antifriction layer by a vacuum bag, and adhering and curing the antifriction layer to obtain the adapter.

In summary, the adapter is manufactured by taking the PMI composite foam as a main body, and the adapter has high mechanical property, high heat resistance and long-term stability; the PMI composite foam is prepared by using an adhesive with special chemical components and curing characteristics, so that the problem that the PMI composite foam cannot be adhered to the resin in the resin foaming process is solved; the adhesive of the PMI composite foam contains a high-efficiency flame retardant with special components, so that the adhesive has high flame retardant property far superior to that of PMI body flame retardant foam; the adapter is manufactured by using a closed-die foaming process, so that the work efficiency reduction and material loss caused by bonding and processing of foam plates are avoided; the inner cavity of the metal mold and the surface possibly contacting materials are coated with the fluoroplastic non-stick coating at high temperature, so that the problem of product sticking is solved. The raw material formula for preparing the foamable resin particles contains part of low-cost raw material monomers and special flame retardants, so that the foam particle bodies have high cost performance and certain flame retardance.

Compared with the traditional composite foam or the foam adapter, the flame-retardant PMI composite foam standard plate material can be prepared in an in-mold foaming mode in the prior art, and then the plate material is cut, bonded, processed and bonded with metal pieces and bonding surface layer materials to prepare the adapter. The method can also obtain the foam material with high flame retardance, but does not have the advantages of improving the work efficiency and saving materials of in-mold foaming; the prior art can also be used to prepare foamable resin particles from formulations that do not contain acrylonitrile. Flame retardant composite foam materials can also be obtained, but the cost performance of the resin is not high; in the prior art, the flame-retardant PMI composite foam adapter without the surface layer material can be prepared by an in-mold foaming mode, and then the adapter can be prepared by machining and bonding the surface layer material. The method has more complex working procedures and lower work efficiency than the technology of the invention.

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 characteristics thereof. Although the present disclosure describes embodiments in terms of one embodiment, not every embodiment is provided with only one embodiment, and the description is for clarity only, and those skilled in the art should recognize that the embodiments described in the disclosure may be combined appropriately to form other embodiments that will be understood by those skilled in the art.

Claims (5)

1. The utility model provides a PMI composite foam adapter, includes foam body, location separating mechanism, antifriction layer, its characterized in that:

the positioning and separating mechanism is inlaid in the foam body and is adhered and fixed with the foam to form a whole;

the foam body is flame-retardant PMI composite foam, and the bottom of the foam body is adhered to the antifriction layer;

and an adhesive is arranged between the flame-retardant PMI composite foam and the antifriction layer to realize firm adhesion.

2. A PMI syntactic foam adaptor according to claim 1, in which the antifriction layer is a chemically treated polytetrafluoroethylene film.

3. The PMI syntactic foam adaptor according to claim 1, in which the positioning and separating mechanism comprises: the aircraft comprises a base, a cover plate, a spring and a pin shaft, wherein the base is fixedly connected with the cover plate through a screw, the spring is arranged in the base, the bottom of the pin shaft is propped against the spring, and the cover plate outwards penetrates through a connecting hole for being inserted into an aircraft shell.

4. A method for producing a PMI syntactic foam adaptor according to any of claims 1 to 3, characterized in that it comprises the steps of:

step one: preparing foamable PMI resin particles with high cost performance;

step two: mixing the resin particles with an adhesive and a flame retardant to adhere a layer of adhesive mixture to the surfaces of the particles;

step three: placing foamable resin particles with adhesive mixture attached on the surface in a female mold of a foaming mold, and closing the mold;

step four: placing the mould into a curing furnace for temperature programming, expanding and foaming foamable resin particles in the mould, filling the mould cavity with materials, performing cyclization and crosslinking reaction on PMI foam in a high-temperature environment, and performing curing reaction on an adhesive to bond foam particles into a whole;

step five: cooling the mould, opening the mould, demoulding, taking out the adapter blank, and trimming burrs of the adapter blank;

step six: the metal separation mechanism base is bonded and fixed at the position of a reserved hole in the PMI foam body formed by the die, and after the adhesive is solidified, a spring, a pin shaft and a cover plate are installed;

step seven: the cut antifriction layer is adhered to the PMI foam body, and is fixed through a vacuum bag, and the adapter is obtained after adhesion and solidification.

5. The method for producing PMI syntactic foam adaptor in mold foaming according to claim 4, wherein the PMI resin particle preparation process in the step one includes:

step one: the preparation method comprises the following steps of: methacrylic acid: 20 to 150 parts of methacrylonitrile: 10 to 80 parts of acrylonitrile: 5 to 80 parts of a third monomer: 0.1 to 6 parts of an initiator: 0.04 to 10 parts of a cross-linking agent: 0.02 to 5 parts of foaming agent: 0.5 to 25 parts of a flame retardant: 5 to 25 parts of other auxiliary agents: 0.9 to 20 parts of other auxiliary agents including, but not limited to, one or more combinations of retarder, nucleating agent, dispersant, mold release agent, heat resistant agent, antioxidant;

step two: uniformly mixing the component materials metered in the first step to obtain a raw material mixed solution;

step three: pouring the raw material mixed solution into a mould with a plurality of small cavities with diameters of 1-15 mm; sealing the die; the mold is placed in a water bath of 30 ℃ to 50 ℃ for polymerization for 10 to 60 hours, then in a water bath of 50 ℃ to 70 ℃ for polymerization for 4 to 40 hours, then in an oven of 70 ℃ to 120 ℃ for polymerization for 5 to 20 hours, the mold is cooled, and the foamable copolymer resin particles are obtained after demolding.