CN110272542A - The preparation method of a kind of amic acid lotion and its modified to the surface of glass fibre - Google Patents

Abstract

The invention belongs to the field of glass fiber sizing agent and relates to the preparation of amic acid emulsion and the surface modification of glass fiber. The present invention controls the molar ratio of aromatic dianhydride and 4,4'-diaminodiphenyl ether to 1.05:1 to 2:1 and the volume ratio of water to N,N'-dimethylformamide to 2:1 to 10 : 1, and add 0.01-5% of acid or neutral water-soluble polymer to prepare milky white amic acid emulsion with solid content of 0.1-5%, and use micro-debonding method to measure interfacial shear strength to determine the effect of amic acid emulsion on glass fiber surface modification effect. The present invention utilizes active groups such as ‑COOH and ‑NH in the emulsion to react with silicon hydroxyl groups on the surface of glass fibers to form firm hydrogen bonds or chemical bonds. Good compatibility to improve the interfacial properties of fibers, has broad application prospects.

Description

A kind of preparation method of amic acid emulsion and its surface modification to glass fiber

technical field

The invention belongs to the field of glass fiber sizing agent and relates to a preparation method of amic acid emulsion and surface modification of glass fiber.

Background technique

Glass fiber reinforced resin matrix composites are widely used in aerospace manufacturing, auto parts, electronic products, light industrial machinery and other fields because of their advantages of light weight, high strength, low price and good mechanical properties. However, the toughness of glass fiber is not strong, the elongation at break is low, and problems such as filament breakage occur during the manufacturing process. Coating and film formation will be carried out during the production process. The sizing agent can play two roles in it: one is Endow the fiber with controllable apparent properties, make the fiber into a fiber bundle with a certain width and hardness, and reduce the number of hairs caused by friction during the production process; the second is to coat the surface of the fiber with a layer of film, and the resin matrix It acts as a bridge between fibers, enhances the compatibility between fibers and resins, reduces stress concentration and improves overall mechanical properties. The current sizing has very excellent effects, but further exploration is still needed to solve the shortcomings of easy decomposition by heating, poor interface temperature resistance, and poor interface adhesion with resin.

Contents of the invention

The present invention aims at the defect that the current common glass fiber sizing agent has good film-forming and clustering performance, but poor interface temperature resistance and poor binding effect with resin, and provides a preparation method of amic acid emulsion and its effect on glass fiber. surface modification. On the one hand, the surface of glass fiber is rich in silicon hydroxyl groups, which can form strong hydrogen bonds with active groups such as -COOH and -NH in amic acid. During the heating and drying process, part of the silicon hydroxyl group can dehydrate with the carboxyl group to form a chemical bond, and the glass fiber and the film layer are tightly combined. On the other hand, the imide formed after heating imidization of amic acid has good temperature resistance, and contains organic groups such as benzene ring and oxygen-containing functional groups. Not only, according to the principle of "similar compatibility", it has good compatibility with resins. compatibility. Amic acid emulsion can be used as a component of the sizing agent, or it can be used alone to modify the glass fiber to improve the interfacial shear strength.

In order to achieve the above object, the present invention adopts the following technical solutions:

An amic acid emulsion, comprising: aromatic dianhydride, 4,4'-diaminodiphenyl ether, N,N'-dimethylformamide, acidic or neutral water-soluble polymer and water. Acidic or neutral water-soluble polymers include one or more mixtures of polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, and polyacrylamide. The mass consumption of each component accounts for the percentage of emulsion gross mass and expresses as follows:

(1) Aromatic dianhydride 0.1~5%

(2) 4,4'-diaminodiphenyl ether 0.1～2.5%

(3) Acidic or neutral water-soluble polymer 0.05～5%

(4) N,N'-Dimethylformamide 5～30％

(5) The balance is deionized water.

In the said emulsion, the volume ratio of water to N,N'-dimethylformamide is 2:1-10:1.

In the emulsion, the molar ratio of aromatic dianhydride to 4,4'-diaminodiphenyl ether is 2:1-1.05:1.

The aromatic dianhydrides include pyromellitic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfide tetraacid One or more mixtures of dianhydride and 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

The emulsion is a synthetic amic acid-containing emulsion with a pH value of 1-5, and the amic acid accounts for 50-90% of the solid mass of the emulsion based on its solid mass. The acidic or neutral water-soluble polymer accounts for 5-30% of the solid mass of the emulsion based on its solid mass.

The preparation method of described amic acid emulsion comprises the following steps:

Step 1, weigh each component raw material as required

Step 2: Dissolve the aromatic dianhydride in N,N'-dimethylformamide at a temperature of 0-30°C, stir until the solid is fully dissolved, then add 4,4'-diaminodiphenyl ether, and stir until After the solid is fully dissolved, let it stand for 5-60 minutes to obtain solution A

Step 3: Add solution A dropwise to deionized water to form a blue-white hydrosol system spontaneously. Stir at a temperature of 0-30°C and a speed of 50-250r/min to prepare an amic acid emulsion

Step 4, dissolving an appropriate amount of acidic or neutral water-soluble polymer to obtain a milky white uniform and stable amic acid emulsion with a solid content of 0.1-5%.

The particle size of the emulsion is 50-1000nm, and the average particle size is 80-200nm.

The surface modification can be applied to silicate-based reinforcing materials, including one or more of silicate nanofibers, montmorillonite, ceramic powder, and kaolin. The main component of silicate reinforcing materials is SiO ₂ , the surface is rich in silicon hydroxyl groups, and the modification mechanism is consistent with that of glass fibers.

Described glass fiber surface modification comprises the following steps:

Step 1, uniform dip coating of glass fiber in emulsion

Step 2, the coated glass fiber is ventilated and dried at 50-200°C for 5-100min

Step 3: Dry the treated glass fiber and epoxy resin at 60-180°C for 2-24 hours to prepare a micro-debonding sample, and measure the interfacial shear strength to judge the surface modification effect of the amic acid emulsion on the glass fiber.

The advantages of the present invention are that the emulsion has good stability, uniform particle size dispersion, and reaches the practical application level; after the emulsion is treated with fiber, it is heated and dried, and the imidization process is carried out, and the imidization product has good heat resistance and good interface resistance. Temperature; the preparation process of the amic acid emulsion and the surface modification process are simple and feasible; using water as the carrier, it is relatively environmentally friendly, with little pollution, suitable for large-scale industrial production, and has a good prospect.

Description of drawings

Fig. 1 is the TEM photo of the amic acid emulsion prepared by the present invention

Figure 2 is the AFM photo of the glass fiber surface before modification

Fig. 3 is the AFM photo of the glass fiber surface modified by the amic acid emulsion prepared in the present invention.

Detailed ways

The technical solutions of the present invention will be further described below with specific examples, but the protection scope of the present invention is not limited thereto.

Example 1

This example provides a preparation method of amic acid emulsion and its surface modification effect on glass fibers, including: 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-di Aminodiphenyl ether, N,N'-dimethylformamide, polyvinylpyrrolidone and water. The mass consumption of each component accounts for the percentage of emulsion gross mass and expresses as follows:

(1) 3,3',4,4'-benzophenone tetracarboxylic dianhydride 0.2%

(2) 4,4'-diaminodiphenyl ether 0.1%

(3) Polyvinylpyrrolidone 0.1%

(4) N,N'-Dimethylformamide 25%

(5) The balance is deionized water.

The preparation method of the amic acid emulsion of the present embodiment comprises the following steps:

Step 1, weigh each component raw material as required

Step 2: Dissolve 0.2g of 3,3',4,4'-benzophenonetetracarboxylic dianhydride in 25ml of N,N'-dimethylformamide at 25°C, stir until the solid is fully dissolved, then add 0.1g of 4,4'-diaminodiphenyl ether, stirred until the solid was fully dissolved and then left to stand for 10min to obtain solution A

Step 3: Add solution A dropwise to 75ml of deionized water to form a blue-white hydrosol system spontaneously. Stir at a temperature of 25°C and a speed of 150r/min to prepare an amic acid emulsion

Step 4: Dissolve 0.1 g of polyvinylpyrrolidone in the amic acid emulsion to obtain 100 ml of milky white uniform and stable emulsion with a solid content of 0.4%.

The pH value of the emulsion is 2.7, the particle size distribution is 20-250nm, and the average particle size is 103nm.

The present embodiment adopts micro-debonding method to carry out the mensuration of interfacial shear strength, comprises the following several steps:

Step 1, uniform dip coating of glass fiber in emulsion

Step 2: Air-dry the coated glass fiber at 60°C for 60 minutes

Step 3: Micro-debonded samples were prepared with the treated glass fiber and epoxy resin, dried at 100°C for 12 hours, and the interfacial shear strength was measured.

In this example, before and after the modification of the amic acid emulsion, the interfacial shear strength between the glass fiber and the epoxy resin increased from 20.06MPa to 32.70MPa, an increase of 63.01%.

Example 2

This example provides a preparation method of amic acid emulsion and its surface modification effect on glass fiber, including: pyromellitic anhydride, 4,4'-diaminodiphenyl ether, N,N'-dimethyl Formamide, polyethylene glycol and water. The mass consumption of each component accounts for the percentage of emulsion gross mass and expresses as follows:

(1) Pyromellitic anhydride 0.227%

(2) 4,4'-diaminodiphenyl ether 0.173%

(3) Polyethylene glycol 0.05%

(4) N,N-Dimethylformamide 20%

(5) The balance is deionized water.

The preparation method of the amic acid emulsion of the present embodiment comprises the following steps:

Step 1, weigh each component raw material as required

Step 2: Dissolve 0.227g of pyromellitic anhydride in 20ml of N,N'-dimethylformamide at 20°C, stir until the solid is fully dissolved, then add 0.173g of 4,4'-diaminodiphenyl Ether, stirred until the solid was fully dissolved and left to stand for 5min to obtain solution A

Step 3: Slowly add solution A to 80ml of deionized water drop by drop to form a blue-white hydrosol system spontaneously. Stir at a temperature of 20°C and a speed of 100r/min to prepare an amic acid emulsion

Step 4: Dissolve 0.05 g of polyethylene glycol in the amic acid emulsion to obtain 100 ml of milky white uniform and stable emulsion with a solid content of 0.45%.

The pH value of the emulsion is 2.6, the particle size distribution is 25-650nm, and the average particle size is 140nm.

The present embodiment adopts micro-debonding method to carry out the mensuration of interfacial shear strength, comprises the following several steps:

Step 1, uniform dip coating of glass fiber in emulsion

Step 2: Air-dry the coated glass fiber at 80°C for 40 minutes

Step 3: Micro-debonded samples were prepared with the treated glass fiber and epoxy resin, dried at 120°C for 8 hours, and the interfacial shear strength was measured.

According to this example, before and after the modification of the amic acid emulsion, the interfacial shear strength between the glass fiber and the epoxy resin increased from 20.07MPa to 30.54MPa, an increase of 52.16%.

Claims (8)

1. a kind of preparation method of amic acid lotion and its surface modification to glass fibre, which is characterized in that the lotion packet Include: aromatic dianhydride, 4,4'- diaminodiphenyl ethers, N, N'- dimethylformamide, acid or neutral water-soluble polymers and Water；Acid or neutral water-soluble polymers include polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polyacrylamide One or more mixing；The percentage that the quality dosage of each component accounts for lotion gross mass is expressed as follows:

(1) aromatic dianhydride 0.1~5%

(2) 4,4'- diaminodiphenyl ether 0.1~2.5%

(3) acid or neutral water-soluble polymers 0.05~5%

(4) N, N'- dimethylformamide 5~30%

(5) surplus is deionized water.

2. a kind of amic acid lotion as described in claim 1, which is characterized in that water and N, the volume of N'- dimethylformamide Than for 2:1~10:1.

3. a kind of amic acid lotion as described in claim 1, which is characterized in that aromatic dianhydride and 4,4'- diamino hexichol The molar ratio of ether is 2:1~1.05:1.

4. aromatic dianhydride as described in claim 1, which is characterized in that including pyromellitic dianhydride, 3,3', 4,4'- hexichol Ketone tetracarboxylic dianhydride, 3,3', 4,4'- diphenyl sulfide tetracid dianhydride, 2,3,3', one kind of 4'- diphenyl ether tetraformic dianhydride or Several mixing.

5. a kind of amic acid lotion as described in claim 1, which is characterized in that pH value is 1~5, and amic acid is with its solid matter Meter accounts for the 50~90% of emulsion solids quality, and acid or neutral water-soluble polymers account for emulsion solids in terms of its solid masses The 5~30% of quality.

6. a kind of a kind of preparation method of amic acid lotion as described in claim 1-3, which is characterized in that including following Step:

Step 1 weighs each component raw material as required

Aromatic dianhydride is dissolved in N by step 2, and in N'- dimethylformamide, 0-30 DEG C of temperature, stirring is sufficiently dissolved to solid Afterwards, 4,4'- diaminodiphenyl ether is added, stirring stands 5-60min to solid after completely dissolution, obtains solution A

Solution A is added dropwise in deionized water the blue and white hydrosol system that can spontaneously form, 0-30 DEG C of temperature, turned by step 3 Fast 50-250r/min stirring, is configured to amic acid lotion

Step 4 dissolves appropriate acid or neutral water-soluble polymers, and the milky for obtaining solid content 0.1-5% is uniform and stable Amic acid lotion.

7. surface as described in claim 1 is modified, which is characterized in that may be implemented in the reinforcing material of silicates, including silicon The reinforcing material surface of silicate nanometer fiber, montmorillonite, ceramic powder, kaolinic one or more, silicates is rich in silicon hydroxyl Base, mechanism of modification are consistent with glass fibre.

8. modified to the surface of glass fibre as described in claim 1, which is characterized in that including the following steps:

Glass fibre is carried out disposable homogeneous immersion coating by step 1 in lotion

Step 2, by the glass fibre after coating at 50-200 DEG C aeration-drying 5-100min

Step 3, with treated glass fibre and epoxy resin it is dry after prepare micro- de- glutinous sample, measure interface shear strength, To judge amic acid lotion to the surface modification effect of glass fibre.