CN111004408A - Preparation method of white-point-free fast-curing epoxy prepreg - Google Patents
Preparation method of white-point-free fast-curing epoxy prepreg Download PDFInfo
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- CN111004408A CN111004408A CN201911335011.4A CN201911335011A CN111004408A CN 111004408 A CN111004408 A CN 111004408A CN 201911335011 A CN201911335011 A CN 201911335011A CN 111004408 A CN111004408 A CN 111004408A
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- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/24—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs
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- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/4007—Curing agents not provided for by the groups C08G59/42 - C08G59/66
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- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/50—Amines
- C08G59/5046—Amines heterocyclic
- C08G59/5053—Amines heterocyclic containing only nitrogen as a heteroatom
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- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
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- C08J2463/04—Epoxynovolacs
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Abstract
The invention discloses a preparation method of a white-point-free fast curing epoxy prepreg, which comprises the following steps: mixing conventional epoxy resin, polyfunctional group resin, low-profile resin and curing agent to prepare a resin film raw material of a homogeneous epoxy resin system; preparing a resin film raw material into a resin film by using a film coating machine, and impregnating the resin film and the fiber fabric by using impregnation equipment to prepare a prepreg; the curing agent is a latent curing agent which can complete curing within 2-15min at the temperature of 120-150 ℃. Aiming at different curing agent types, the invention realizes the homogeneous structure of the resin system by mixing, ensures that the whole epoxy system reaches a mutual soluble state before curing or during curing, thereby eliminating the residues of the curing agent and other byproducts, meeting the requirements of fast curing and realizing the production of white-point-free products, and having strong practicability and wide applicability in the field of automobiles.
Description
Technical Field
The invention relates to a preparation method of a prepreg, in particular to a preparation method of a white-point-free fast curing epoxy prepreg, and belongs to the technical field of epoxy prepregs.
Background
In recent years, global fuel economy is severe, more severe emission standards are provided, high-grade requirements are provided for the automobile manufacturing industry, and composite materials with good weight reduction effects are widely applied to the automobile field for reducing fuel energy consumption.
The thermosetting resin prepreg has higher cost performance and can be applied most fully. At present, the applied parts cover almost the whole automobile, such as parts of a radiator support, a bumper, an engine hood, a vehicle hood, a chassis, a suspension and the like. And to car shell body structure, the structure is simple relatively, for improving production efficiency, reduction in production cost satisfies the urgent needs in market, and fast curing epoxy preimpregnation material takes place at the same time. The traditional epoxy prepreg curing mode is changed, the heat inlet and outlet of parts are realized, and the production efficiency of stamping metal parts is approximate.
The number of similar products at home and abroad is not enough, and most of the products can meet the curing requirement of 150 ℃ for 5-10min on the market. For example, ACTECH 1201 from the Navigator industry, HexPly M77HF from Cyanid, EM118 from Jiangsu Henshengshen, and the like.
With the application of fast curing prepregs to automotive parts, one industry challenge is exposed: white spots or white spots appear on the surface of the part after being washed by water, acetone and the like, and the acceptance pass rate of the automobile appearance part is seriously influenced. Although the polishing can play a certain role in eliminating, permanent damage can be caused to the fibers, and the fibers cannot be completely eliminated, so that the labor and the financial resources are consumed.
According to analysis, the general curing agent system in the market at present is powder dicyandiamide matched with an organic urea accelerator, and a small amount of residual dicyandiamide or byproducts are generated during rapid curing and forming, are insoluble in an epoxy system and appear after meeting water or a solvent.
The fibers in the fast curing prepreg can be carbon fibers, glass fibers, polyester fibers, aramid fibers, basalt fibers and the like, and for the white spot problem mentioned in the invention, the fibers basically appear in the fiber prepreg with a dark color, most notably the carbon fiber prepreg, and the weaving form of the fibers is also a unidirectional, plain, twill and long-length fiber fabric, a unidirectional sheet chopped fiber or non-woven fabric and the like.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a preparation method of a prepreg, which solves the problem that white spots are generated by washing with water and acetone after the conventional fast curing prepreg is cured.
In order to achieve the above object, the present invention adopts the following technical solutions:
a preparation method of a white-spot-free fast curing epoxy prepreg comprises the following steps:
s1, mixing conventional epoxy resin, polyfunctional group resin and low-profile resin to obtain mixed resin;
s2, mixing the mixed resin with a curing agent to prepare a resin film raw material of a homogeneous epoxy resin system;
s3, coating the raw material of the resin film on a coating machine to prepare the resin film when the raw material is mixed for use; the existing mixing process is directly carried out in the next coating process without cooling after the resin mixing is finished;
s4, impregnating the resin film and the carbon fiber fabric through impregnation equipment to prepare a prepreg;
the curing agent is a latent curing agent which can complete curing within 2-15min at the temperature of 120-150 ℃.
And (3) preparing the homogeneous epoxy resin system in the step S1, and mixing for 20-60min at the temperature lower than 120 ℃.
The curing agent in the above step S2 has three types: a class I curing agent, a class II curing agent and a class III curing agent;
a. the I-type curing agent is a liquid curing agent and comprises one or more of liquid dicyandiamide and fujicure series.
The liquid dicyandiamide has good room-temperature storage life, and is matched with organic urea for use when in use, so that the quick curing effect is achieved. The organic urea can be one of UR300, UR500 and UR700, the mixing mass ratio of the liquid dicyandiamide to the organic urea is (0.8-1.2) to (0.2-0.5), and more preferably, the mixing mass ratio of the liquid dicyandiamide to the organic urea is (0.8-1.2): UR300 ═ 1-1.2 (0.3-0.4). The dosage of the curing agent accounts for 8 to 15 percent of the total mass, and the curing agent is abbreviated as I-1 curing agent.
The Fujicure series curing agent can be one of Fujicure7000 and Fujicure7001 of Fuji chemical company of Japan, has good latency, has a viscosity of 1000-5000cps at 25 ℃, is light yellow or red brown, and is used in an amount of 5-20% of the total mass, preferably 10-15% of the total mass, and is simply called as I-2 type curing agent.
b. Group II curing agents: the curing agent is a solid curing agent with a melting point lower than 120 ℃, and comprises one or more of FXR series, long-chain alkyl imidazole and microcapsule curing agent.
The FXR series curing agent is one of FXR-1020, FXR-1030 and FXR-1121 of Fuji chemical company of Japan, has a particle size of 1-30 μm, and is easily dispersed in a resin system. The amount of the curing agent is 5-20% of the total mass, preferably 10-15% of the total mass, and is abbreviated as II-1 curing agent.
Long chain alkyl imidazoles, are of the class having- (CH)2) Modified imidazoles of the n-structure having a particle size of from 5 to 100 microns, where n is from 10 to 20, preferably from 14 to 18. The amount of the curing agent is 3-10% of the total mass, preferably 4-7% of the total mass, and is abbreviated as II-2 type curing agent.
The microcapsule curing agent is prepared by wrapping curing agent particles as core materials by a coating technology to realize the characteristic of latency, and breaking shells under the action of heating or pressure to realize curing. The core material of the curing agent needs to be dissolved at a low melting point of 120 ℃, such as 2E4MZ, 2E4MZ-CN, diphenyl imidazole and the like, and the particle size is 0.5-20 microns. The amount of the curing agent is 10-25% of the total mass, preferably 13-21% of the total mass, and is abbreviated as II-3 curing agent.
c. Group III curing agents: the curing agent is a combination of ortho-position or para-position Diamino Diphenyl Sulfone (DDS) and an accelerator, and the mass ratio of the curing agent to the accelerator is (8-12): (0.8-1.2); preferably, the mass ratio is 10: 1.
the curing agent is ortho-position or para-position diamino diphenyl sulfone, and the accelerator comprises 2E4MZ, 2E4MZ-CN and 2P4 MHZ.
Further, the mixing temperature of the I or II curing agent is 50-80 ℃, and the mixing time is 10-30 min; the mixing temperature of the III curing agent is 110-120 ℃, the mixing time is 20-40min, then the temperature is reduced to 50-80 ℃, and the accelerator is added and mixed for 10-30 min.
The temperature of the coating film in the step S3 is 45-75 ℃, and the temperature of the impregnation roller in the step S4 is not higher than 80 ℃.
The fiber fabric in the step S4 is a reinforcing material, and may be any conventional fiber with any structure in the automobile industry, and is preferably a carbon fiber twill fabric, the number of the fiber tows is 1-24K, the strength is 3600-4900MPa, and is preferably a constant-gravity HFW200T twill carbon fiber fabric, and the fabric areal density is 200 gsm. The type of sizing agent used for impregnation is epoxy, such as a loose sizing agent DHS-110, a compound denier sizing agent N-106, a Hengshen No. 3 sizing agent and the like.
The conventional epoxy resin in the step S1 is one or more of bisphenol A epoxy resin with an epoxy equivalent of 180-3000g/eq and bisphenol F epoxy resin with a low molecular weight, and can be one or more of NPEF-901, NPEF-170, NPEF-128 and NPPN-608S, NPEL-136, wherein the mass of the conventional epoxy resin accounts for 20-45% of the total mass, and is preferably 27-35% of the total mass, and the conventional epoxy resin is used for adjusting the viscosity and the fluidity of the system.
The multifunctional resin in the step S1 is one or more of multifunctional novolac epoxy resin and multifunctional epoxy resin, and comprises one or more of TDE-85, AG-80, AFG-90 and triglycidyl ortho-aminophenol, and the mass of the multifunctional resin accounts for 15-45% of the total mass. The polyfunctional resin is used for improving the heat resistance of a system, realizing the demoulding of the fast curing prepreg at high temperature, effectively reducing the curing shrinkage, having low linear expansion coefficient at high temperature and improving the surface quality.
The multifunctional novolac epoxy resin preferably has a functional group number of 4 to 12, and may be bisphenol a type novolac epoxy, such as KEB-3180 of korea kolon; more preferably, the naphthol novolac epoxy (hereinafter abbreviated as (NF-n)) is prepared by condensation polymerization of naphthol, a catalyst, aldehydes and the like in a high temperature environment, and has a structural formula:
wherein n is 1 to 10, preferably, n is 3 to 5; r is
The amount, type and proportion of the multifunctional resin in the epoxy system are determined according to different curing agent types and differences of heat resistance of the epoxy system. The main theory is that the multifunctional epoxy resin has the optimal heat resistance, but generally has more serious curing shrinkage and needs to control the dosage; the multifunctional novolac epoxy cited in the invention has excellent heat resistance and low coefficient of linear expansion, and can effectively reduce the contractility.
In the I-1 and III curing agent systems, the dosage of the multifunctional novolac epoxy resin accounts for 15-45% of the total mass, preferably, 25-40% of the total mass;
in the I-2, II-1, II-2 and II-3 curing agent systems, multifunctional novolac epoxy resin and multifunctional epoxy resin are simultaneously present, the mass ratio of the multifunctional novolac epoxy resin to the multifunctional epoxy resin is 2 (0.8-1.2), and the using amount of the multifunctional novolac epoxy resin to the multifunctional epoxy resin accounts for 15% -40% of the total mass, preferably 25% -40% of the total mass.
The low-profile resin in step S1 is a urethane-modified epoxy resin, and can be prepared by pre-polymerizing a high molecular weight polyethylene glycol and an isocyanate, and then fully reacting the pre-polymerized product with an epoxy resin, a catalyst, a solvent, and the like. Preferably XP-602 of Shanghai Zhongsi industries, Inc., or ERS-133, ERS-DC12, EPU-73B of Aidi, of Shanghai Zhongsi industries, Inc. The amount of the compound is 10-20%, preferably 13-18% of the total mass. The curing shrinkage is reduced by the low profile characteristic of the polyurethane resin, so that the appearance quality of the cured resin is improved.
The invention has the advantages that:
the preparation method of the white-point-free fast curing epoxy prepreg comprises the steps of forming the curing agent system of the invention by three types of curing agents, optimizing resin components in the resin system aiming at different curing agent types, searching for balance between improving heat resistance and reducing curing shrinkage by selecting different polyfunctional group resins, and improving the surface quality of a cured product on the premise of not influencing hot demolding; by introducing a low-profile resin system, the shrinkage of the epoxy resin caused by concentrated heat release during rapid curing is reduced, and good appearance quality is achieved; by optimizing the formula, the effect of the A-grade surface of the workpiece can be achieved.
The preparation method of the white-point-free fast curing epoxy prepreg provided by the invention has the advantages that the mixing or dissolving mode and the reactivity of the curing agent are judged according to different curing agent types, the homogeneous structure of a resin system is realized through a certain mixing sequence, temperature and time, the whole epoxy system is ensured to reach a mutual soluble state before curing or during curing, the resin implosion caused by the too fast reaction of the curing agent in the mixing process is avoided, the reactivity of the system is kept, the residues of the curing agent and other byproducts are eliminated, the production of white-point-free products is realized while the fast curing is realized, and the curing of a plurality of systems can be realized at 120 ℃ for 10 min. In addition, the invention provides the existing mixing method for producing the prepreg, which not only can reduce the risk of implosion of high-activity products in the production process, particularly in the glue drying process, but also can improve the production efficiency and save energy.
Detailed Description
The present invention will be described in detail with reference to the following embodiments.
Example 1
A white-point-free fast curing epoxy prepreg is disclosed, wherein in a resin system: 25 parts of NPEF-901 epoxy resin, 10 parts of NPEF-128 epoxy resin, 38 parts of NF-4 naphthol novolac epoxy resin and 16 parts of XP-602 polyurethane modified epoxy resin; 8 parts of liquid dicyandiamide; UR500 accelerator 3 parts.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: firstly, mixing liquid dicyandiamide and UR500 by using high-speed centrifugal dispersion equipment, controlling the rotating speed at 3000r/min, and preparing a curing agent paste for later use;
adding NPEF-901 epoxy resin, NPEF-128 epoxy resin, NF-4 naphthol novolac epoxy resin and XP-602 polyurethane modified epoxy resin into a mixing kettle, heating to 85 ℃, and mixing for 20min until the epoxy resin is completely dissolved; cooling to 70 deg.C, adding the above curing agent paste, and mixing for 15min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to be 70 ℃, and preparing the resin film;
(4) the temperature of each impregnation roller of the impregnation equipment is controlled at 60-70 ℃, and the resin film and the Hengshen HFW200T carbon fiber twill fabric are impregnated to prepare the prepreg.
Example 2
A white-point-free fast curing epoxy prepreg, the resin system: 25 parts of NPEF-901 epoxy resin, 9 parts of NPEF-170 epoxy resin, 24 parts of NF-4 naphthol novolac epoxy resin, 13 parts of AFG-90 epoxy resin and 17 parts of XP-602 polyurethane modified epoxy resin; 12 parts of fujicure7000 curing agent.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: adding NPEF-901 epoxy resin and NPEF-170 epoxy resin into a mixing kettle, heating to 90 ℃, and mixing for 20min until complete dissolution; then cooling to 80 ℃, adding NF-4 naphthol novolac epoxy resin, AFG-90 epoxy resin and XP-602 polyurethane modified epoxy resin, and mixing for 15 min; cooling to 70 ℃, adding fujicure7000, and mixing for 15min to obtain a resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to be 68 ℃ and preparing the resin film;
(4) the temperature of each impregnation roller of the impregnation equipment is controlled at 55-65 ℃, and the resin film and the Hengshen HFW200T carbon fiber twill fabric are impregnated to prepare the prepreg.
Example 3
A white-point-free fast curing epoxy prepreg, the resin system: 22 parts of NPEF-901 epoxy resin, 10 parts of NPEF-128 epoxy resin, 24 parts of NF-4 naphthol novolac epoxy resin, 15 parts of AG-80 epoxy resin and 16 parts of XP-602 polyurethane modified epoxy resin; 13 parts of FXR-1020 curing agent.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: firstly, FXR-1020 and NPEF-128 epoxy resin are mixed by using high-speed centrifugal dispersion equipment, the rotating speed is controlled at 3000r/min, and curing agent paste is prepared for standby application;
adding NPEF-901 epoxy resin, NF-4 naphthol novolac epoxy resin, AG-80 epoxy resin and XP-602 polyurethane modified epoxy resin into a mixing kettle, heating to 85 ℃, and mixing for 20min until the epoxy resin is completely dissolved; cooling to 70 deg.C, adding the above curing agent paste, and mixing for 15min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to be 70 ℃, and preparing the resin film;
(4) the temperature of each impregnation roller of the impregnation equipment is controlled at 60-70 ℃, and the resin film and the Hengshen HFW200T carbon fiber twill fabric are impregnated to prepare the prepreg.
Example 4
A white-point-free fast curing epoxy prepreg, the resin system: 24 parts of NPEF-901 epoxy resin, 11 parts of NPEF-128 epoxy resin, 28 parts of NF-4 naphthol novolac epoxy resin, 12 parts of AG-80 epoxy resin and 18 parts of XP-602 polyurethane modified epoxy resin; 7 parts of C17Z curing agent.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: firstly, mixing a C17Z curing agent and NPEF-128 epoxy resin by using high-speed centrifugal dispersion equipment, and controlling the rotating speed at 3000r/min to prepare curing agent paste for later use. Adding NPEF-901 epoxy resin, NF-4 naphthol novolac epoxy resin, AG-80 epoxy resin and XP-602 polyurethane modified epoxy resin into a mixing kettle, heating to 100 ℃, and mixing for 15min until the epoxy resin is completely dissolved; cooling to 65 deg.C, adding the above curing agent paste, and mixing for 15min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to 65 ℃, and preparing the resin film;
(4) the temperature of each impregnation roller of the impregnation equipment is controlled at 55-65 ℃, and the resin film and the Hengshen HFW200T carbon fiber twill fabric are impregnated to prepare the prepreg.
Example 5
A white-point-free fast curing epoxy prepreg, the resin system: 20 parts of NPEF-901 epoxy resin, 12 parts of NPEF-128 epoxy resin, 24 parts of NF-4 naphthol novolac epoxy resin, 11 parts of AG-80 epoxy resin and 16 parts of XP-602 polyurethane modified epoxy resin; 17 parts of microcapsule curing agent of 2E4MZ core material.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: firstly, microcapsule curing agent of 2E4MZ core material and NPEF-128 epoxy resin are mixed by high-speed centrifugal dispersing equipment, the rotating speed is controlled at 2000r/min, and curing agent paste is prepared for standby.
Adding NPEF-901 epoxy resin, NF-4 naphthol novolac epoxy resin, AG-80 epoxy resin and XP-602 polyurethane modified epoxy resin into a mixing kettle, heating to 100 ℃, and mixing for 15min until the epoxy resin is completely dissolved; cooling to 65 deg.C, adding the above curing agent paste, and mixing for 15min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to 65 ℃, and preparing the resin film;
(4) the temperature of each impregnation roller of the impregnation equipment is controlled at 55-65 ℃, and the resin film and the Hengshen HFW200T carbon fiber twill fabric are impregnated to prepare the prepreg.
Example 6
A white-point-free fast curing epoxy prepreg, the resin system: 20 parts of NPEF-901 epoxy resin, 13 parts of NPEF-128 epoxy resin, 39 parts of NF-4 naphthol novolac epoxy resin and 17 parts of EPU-73B polyurethane modified epoxy resin; 10 parts of contraposition DDS curing agent; 1 part of 2P4MHZ accelerator.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: adding NPEF-901 epoxy resin, NPEF-128 epoxy resin and EPU-73B into a mixing kettle, heating to 100 ℃, and mixing for 15min until complete dissolution; adding a contraposition DDS curing agent, and mixing until the contraposition DDS curing agent is dissolved; cooling to 65 deg.C, adding 2P4MHZ, and mixing for 10min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to 65 ℃, and preparing the resin film;
(4) the temperature of each impregnation roller of the impregnation equipment is controlled at 55-65 ℃, and the resin film and the Hengshen HFW200T carbon fiber twill fabric are impregnated to prepare the prepreg.
And (3) detection test:
the prepregs prepared in examples 1 to 6 were cut into 300mm × 300mm pieces of 10 pieces, laid and stuck in the same fiber grain direction to form a preform, and laminated plates were prepared by a molding press with a pressure controlled at 6MPa and curing systems different from each other according to different curing systems. The following evaluations were carried out:
a. after demolding, observing the appearance quality, whether the appearance is flat and smooth and has no defects such as pinholes and the like, and observing the appearance color and the transmittance;
b. washing the surface of the plate with water and acetone for 1min, cleaning the surface, and observing whether the defects such as white spots, white spots and the like exist;
c. testing the plate DMA and evaluating the heat resistance;
d. the tack life of the uncured prepreg at 25 ± 3 ℃ was measured.
The test results, as shown in table 1 below:
TABLE 1
As can be seen from the above table 1, the formula system of the present invention not only can meet the requirement of rapid curing, but also has good apparent quality, and the white spot phenomenon does not occur on the surface after washing with water or acetone. The Tg of the plate is high, the requirement of thermal demoulding is met, and high appearance quality can be achieved while high-efficiency production is realized. The class I curing agent can more easily show an A-grade surface, and because the flowability is better, the carbon fiber fabric can be more easily soaked in a high-temperature and high-pressure state; in example 3, the Tg did not reach 130 ℃, but the curing temperature itself was lower, which could satisfy the thermal release requirements. However, the curing agents of group II-2 and group III cause the appearance of the cured product to be reddish, and the product with the appearance which can not meet the requirement of high distinctness of image (DOI) can not be manufactured.
Comparative example 1
In the resin system: 25 parts of NPEF-901 epoxy resin, 10 parts of NPEF-128 epoxy resin, 38 parts of NF-4 naphthol novolac epoxy resin and 16 parts of XP-602 polyurethane modified epoxy resin; 8 parts of dicyandiamide superfine powder with the particle size of 6 mu m; UR500 accelerator 3 parts.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: firstly, mixing superfine powder dicyandiamide and UR500 by using high-speed centrifugal dispersion equipment, controlling the rotating speed at 3000r/min, and preparing into curing agent paste for later use;
adding NPEF-901 epoxy resin, NPEF-128 epoxy resin, NF-4 naphthol novolac epoxy resin and XP-602 polyurethane modified epoxy resin into a mixing kettle, heating to 85 ℃, and mixing for 20min until the epoxy resin is completely dissolved; cooling to 70 deg.C, adding the above curing agent paste, and mixing for 15min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to be 70 ℃, and preparing the resin film;
(4) and (3) controlling the temperature of each impregnation roller of the impregnation equipment to be 60-70 ℃, impregnating the resin film and the prepared HFW200T carbon fiber twill fabric to prepare the prepreg.
Comparative example 2
Resin system: 25 parts of NPEF-901 epoxy resin, 9 parts of NPEF-170 epoxy resin, 24 parts of KEB-3180 resin, 13 parts of AFG-90 epoxy resin and 17 parts of ERS-133 polyurethane modified epoxy resin; 12 parts of fujicure7000 curing agent.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: adding NPEF-901 epoxy resin and NPEF-170 into a mixing kettle, heating to 90 ℃, and mixing for 20min until complete dissolution; then cooling to 80 ℃, adding KEB-3180 resin, AFG-90 epoxy resin and ERS-133 epoxy resin, and mixing for 15 min; cooling to 70 ℃, adding fujicure7000, and mixing for 15min to obtain a resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to be 68 ℃ and preparing the resin film;
(4) and (3) controlling the temperature of each impregnation roller of the impregnation equipment to be 55-65 ℃, impregnating the resin film and the prepared HFW200T carbon fiber twill fabric to prepare the prepreg.
Comparative example 3
Resin system: 35 parts of NPEF-901 epoxy resin, 14 parts of NPEF-170 epoxy resin, 24 parts of KEB-3180 resin and 15 parts of AFG-90 epoxy resin; 12 parts of fujicure7000 curing agent.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: adding NPEF-901 epoxy resin and NPEF-170 into a mixing kettle, heating to 90 ℃, and mixing for 20min until complete dissolution; then cooling to 80 ℃, adding KEB-3180 resin and AFG-90 epoxy resin, and mixing for 15 min; cooling to 70 ℃, adding fujicure7000, and mixing for 15min to obtain a resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to be 68 ℃ and preparing the resin film;
(4) and (3) controlling the temperature of each impregnation roller of the impregnation equipment to be 55-65 ℃, impregnating the resin film and the prepared HFW200T carbon fiber twill fabric to prepare the prepreg.
Comparative example 4
Resin system: 22 parts of NPEF-901 epoxy resin, 10 parts of NPEF-128 epoxy resin, 39 parts of NF-4 naphthol novolac epoxy resin and 16 parts of XP-602 polyurethane modified epoxy resin; 13 parts of FXR-1020 curing agent.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: firstly, FXR-1020 and NPEF-128 epoxy resin are mixed by using high-speed centrifugal dispersion equipment, the rotating speed is controlled at 3000r/min, and curing agent paste is prepared for standby application; adding NPEF-901 epoxy resin, NF-4 naphthol novolac epoxy resin and XP-602 polyurethane modified epoxy resin into a mixing kettle, heating to 85 ℃, and mixing for 20min until the epoxy resin is completely dissolved; cooling to 70 deg.C, adding the above curing agent paste, and mixing for 15min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to be 70 ℃, and preparing the resin film;
(4) and (3) controlling the temperature of each impregnation roller of the impregnation equipment to be 60-70 ℃, impregnating the resin film and the prepared HFW200T carbon fiber twill fabric to prepare the prepreg.
Comparative example 5
Resin system: 20 parts of NPEF-901 epoxy resin, 13 parts of NPEF-128 epoxy resin, 39 parts of NF-4 naphthol novolac epoxy resin and 17 parts of EPU-73B polyurethane modified epoxy resin; 10 parts of contraposition DDS curing agent; 1.1 parts of 2P4MHZ accelerator.
The preparation method comprises the following specific steps:
(1) weighing: weighing raw materials in parts by weight;
(2) resin mixing: adding NPEF-901 epoxy resin, NPEF-128 epoxy resin and EPU-73B into a mixing kettle, heating to 100 ℃, and mixing for 15min until complete dissolution; adding a contraposition DDS curing agent, and mixing until the contraposition DDS curing agent is dissolved; cooling to 65 deg.C, adding 2P4MHZ, and mixing for 10min to obtain resin film raw material;
(3) coating the raw material of the resin film on coating equipment, controlling the roll temperature to 65 ℃, and preparing the resin film;
(4) and (3) controlling the temperature of each impregnation roller of the impregnation equipment to be 55-65 ℃, impregnating the resin film and the prepared HFW200T carbon fiber twill fabric to prepare the prepreg.
The same test method is used for analysis, and specific test results are shown in the following table 2:
TABLE 2
From the comparative examples it can be seen that:
1) even if the superfine dicyandiamide with small particle size still cannot avoid the white spot problem, the powder dicyandiamide cannot exist in a fast curing system, and the liquid dicyandiamide is used to form a homogeneous epoxy resin system with various resins, so that the white spot phenomenon can be effectively avoided;
2) the polyurethane has the characteristic of low profile, epoxy resin is easy to phase split to form a light-tight structure, and when polyurethane modified epoxy is selected, the high-transmittance bright XP-602 is preferred; comparative example 3 has no low profile resin, has obvious curing shrinkage, has poor surface quality, shows no white spots, but still does not meet the quality appearance requirement;
3) for II-1 type curing agents with poor heat resistance and the like, heat resistance needs to be improved through multifunctional epoxy resin, and the heat demolding cannot be realized by only using the multifunctional novolac epoxy resin, so that the apparent quality is reduced due to the peeling of outer layer resin;
4) the dosage of the para-DDS and the accelerator is strictly controlled, and excessive accelerator not only can cause the reduction of the viscosity service life, but also can cause the color of a cured product to be darker and has no light transmittance.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.
Claims (10)
1. A preparation method of a white-spot-free fast curing epoxy prepreg is characterized by comprising the following steps:
s1, mixing conventional epoxy resin, polyfunctional group resin and low-profile resin to obtain mixed resin;
s2, mixing the mixed resin with a curing agent to prepare a resin film raw material of a homogeneous epoxy resin system;
s3, coating the raw material of the resin film on a coating machine to prepare the resin film;
s4, impregnating the resin film and the fiber fabric through impregnation equipment to prepare a prepreg;
the curing agent is a latent curing agent which can complete curing within 2-15min at the temperature of 120-150 ℃.
2. The method as claimed in claim 1, wherein the conventional epoxy resin in step S1 is one or more of bisphenol A epoxy resin with an epoxy equivalent of 180-.
3. The method for preparing a white-point-free fast curing epoxy prepreg according to claim 1, wherein the multifunctional resin in the step S1 is one or more of multifunctional novolac epoxy resin and multifunctional epoxy resin, and the mass of the multifunctional resin accounts for 15-45% of the total mass.
4. The method for preparing a white-point-free fast curing epoxy prepreg according to claim 1, wherein the low-profile resin in the step S1 is a polyurethane modified epoxy resin, and the amount of the low-profile resin is 10-20% of the total mass.
5. The method for preparing a white-point-free fast curing epoxy prepreg according to claim 1, wherein the curing agents in the step S2 are of three types:
a. the I-type curing agent is a liquid curing agent and comprises one or more of liquid dicyandiamide (I-1) and fujicure series (I-2);
b. group II curing agents: the curing agent is a solid curing agent with a melting point lower than 120 ℃, and comprises one or more of FXR (FXR) series (II-1), long-chain alkyl imidazole (II-2) and microcapsule curing agent (II-3);
c. group III curing agents: the curing agent is a combination of ortho-position or para-position diamino diphenyl sulfone and an accelerant, and the mass ratio of the curing agent to the accelerant is (8-12): (0.8-1.2); the curing agent is ortho-position or para-position diamino diphenyl sulfone, and the accelerator comprises 2E4MZ, 2E4MZ-CN and 2P4 MHZ.
6. The method for preparing a white-point-free fast curing epoxy prepreg according to claim 5, wherein in the I-1 and III curing agent systems, the multifunctional resin is a multifunctional novolac epoxy resin;
in the I-2, II-1, II-2 and II-3 curing agent systems, the multifunctional group resin is selected from multifunctional novolac epoxy resin and multifunctional epoxy resin, and the mass ratio of the multifunctional novolac epoxy resin to the multifunctional epoxy resin is 2 (0.8-1.2).
7. The preparation method of the white-point-free fast curing epoxy prepreg according to claim 5, wherein the mixing temperature of the I or II curing agent is 50-80 ℃ and the mixing time is 10-30 min;
in the III curing agent, the mixing temperature of the ortho-position or para-position diamino diphenyl sulfone is 110-120 ℃, the mixing time is 20-40min, then the temperature is reduced to 50-80 ℃, and the accelerant is added and mixed for 10-30 min.
8. The method for preparing a white-point-free fast curing epoxy prepreg according to claim 1, wherein the step S1 is carried out by preparing a homogeneous epoxy resin system and mixing at a temperature of less than 120 ℃ for 20-60 min.
9. The method for preparing a white-spot-free fast curing epoxy prepreg according to claim 1, wherein the coating temperature in the step S3 is 45-75 ℃, and the impregnation roller temperature in the step S4 is not higher than 80 ℃.
10. The method as claimed in claim 1, wherein the fiber fabric in step S4 has a fiber tow number of 1-24K and a strength of 3600-.
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Application publication date: 20200414 |