Aramid yarn and preparation method and application thereof

Abstract

The present invention provides an aramid yarn and a preparation method and application thereof. The preparation method of the aramid yarn comprises the following steps: taking a linear aramid raw material formed by twisting aramid fibers, performing surface treatment with isocyanate to obtain a first intermediate product; performing secondary surface treatment with resin on the first intermediate product to obtain the aramid yarn. The preparation method of the aramid yarn of the present invention first performs surface treatment with isocyanate, and then performs secondary surface treatment with resin, so that the obtained aramid yarn can be better combined with concrete and mortar matrix, has high interface bonding strength, and has good dispersibility and adhesion in concrete and mortar. When the aramid yarn is added to concrete and mortar materials, it can significantly improve the strength, compression resistance, flexural resistance and other mechanical properties of the product.

Description

Technical Field

[0001] The invention relates to the technical field of fiber materials, and in particular to an aramid yarn and a preparation method and application thereof. Background Art

[0002] In the fields of construction, bridges, dams, etc., concrete or mortar materials with cement as one of the main components are commonly used. Since cement does not meet the expected requirements in terms of strength, compression and flexural properties after solidification, in order to prevent the cracking of cement concrete products and improve the compression and flexural properties, asbestos fiber, glass fiber or metal fiber can be used for modification. Since asbestos fiber is carcinogenic, glass fiber has poor toughness, and metal fiber has poor corrosion resistance, its application is subject to certain limitations.

[0003] Aramid fiber (aromatic polyamide fiber) is a high-performance organic fiber, which is divided into poly(p-phenylene terephthalamide) fiber (also known as para-aramid or aramid 1414) and poly(m-phenylene isophthalamide) fiber (also known as meta-aramid or aramid 1313). It has good heat resistance, corrosion resistance, fatigue resistance, wear resistance, high strength and other properties, and has been widely used in life protection, aerospace, composite materials, fiber optic communications, electrical insulation and automotive industries.

[0004] Since aramid fiber is a highly oriented crystalline material with no amorphous region, there are a large number of benzene rings in the molecular chain segments, resulting in large steric hindrance. The molecular chains are arranged in parallel along the axial direction and are completely in a straight and rigid state. The benzene rings have a shielding effect on the hydrogen atoms on the amide functional groups. Therefore, it is difficult for the amide groups to chemically react with other atoms or groups, making the fiber surface inactive. It is therefore difficult to form chemical covalent bonds at the interface, and thus aramid fibers have weaker adhesion to conventional adhesive systems.

[0005] The highly oriented molecular chains of aramid fibers make the fiber surface very smooth and inert. However, there is a certain gap between the modulus of aramid fibers and the matrix materials of concrete and mortar (or asphalt). The two phases are incompatible and have poor dispersion, resulting in stress concentration at the bonding interface and low interfacial bonding strength, which has a great impact on the comprehensive performance of aramid fiber concrete and mortar composites. Summary of the invention

[0006] The purpose of the present invention is to provide an aramid yarn and a preparation method and application thereof, so as to solve the technical problems of poor dispersibility and low interface bonding strength between aramid fibers and concrete / mortar materials in the prior art.

[0007] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0008] A method for preparing an aramid yarn comprises the following steps:

[0009] (1) taking a linear aramid raw material formed by twisting aramid fibers, and performing surface treatment with isocyanate to obtain a first intermediate product;

[0010] (2) The first intermediate product in step (1) is subjected to secondary surface treatment with a resin to obtain an aramid yarn.

[0011] Preferably, in step (1), the isocyanate is one or more of toluene diisocyanate and hexamethylene diisocyanate.

[0012] Preferably, in step (1), the surface treatment comprises the following steps: dipping or coating the isocyanate on the surface of the aramid raw material.

[0013] Preferably, the surface of the aramid raw material is impregnated with an impregnation liquid containing the isocyanate, which is an ethylene glycol solution of toluene diisocyanate and / or hexamethylene diisocyanate, and the weight percentage of the ethylene glycol in the impregnation liquid is 60-70%.

[0014] Preferably, the surface treatment is performed by dipping and then drying at 180-240° C. for 1-3 minutes.

[0015] Preferably, in step (2), the resin is one or more of polyethylene resin, polypropylene resin and polyvinyl alcohol resin.

[0016] Preferably, in step (2), the secondary surface treatment comprises the following steps: heating and melting the resin, placing the first intermediate product in the molten resin, and allowing the resin to cover the first intermediate product.

[0017] Preferably, in step (1), the aramid fiber is poly(p-phenylene terephthalamide) fiber or modified poly(p-phenylene terephthalamide) fiber.

[0018] Preferably, the twist of the linear aramid raw material formed by twisting in step (1) is 30-100 tpm.

[0019] Preferably, the method for preparing the aramid yarn further comprises the step of cutting the aramid yarn obtained in step (2) into segments with a length of 30-100 mm.

[0020] The present invention also provides an aramid yarn prepared by the aramid yarn preparation method.

[0021] The present invention also provides application of the aramid yarn in the field of concrete or mortar materials.

[0022] The above solution of the present invention includes at least the following beneficial effects:

[0023] The preparation method of the aramid yarn of the present invention comprises the following steps: taking a linear aramid raw material formed by twisting aramid fibers, performing surface treatment with isocyanate to obtain a first intermediate product; performing secondary surface treatment with resin on the first intermediate product to obtain the aramid yarn. The preparation method of the aramid yarn of the present invention first performs surface treatment with isocyanate, and then performs secondary surface treatment with resin. On the one hand, isocyanate can increase the roughness of the fiber surface, improve the wettability of the adhesive resin to the aramid fiber, and improve the physical bonding force between the aramid fiber surface and the adhesive resin; on the other hand, it breaks the energy balance relationship between some molecules on the surface of the aramid fiber, stimulates the activity of some groups, and forms a chemical bond with the adhesive resin, thereby improving the bonding strength between the aramid fiber and the adhesive resin. There is a layer of adhesive resin on the surface of the aramid fiber, that is, the adhesive resin layer becomes a gradient transition layer between the aramid fiber and the concrete and mortar, thereby achieving the purpose of better bonding between the aramid fiber and the concrete and mortar matrix. Under the simultaneous action of the physical force and chemical bond between the isocyanate and the surface of the aramid fiber, the obtained aramid yarn can be better combined with the concrete and mortar matrix, with high interface bonding strength, and has good dispersibility and adhesion in concrete and mortar. When the aramid yarn is added to concrete and mortar materials, the mechanical properties such as strength, compression resistance and flexural resistance of the product can be significantly improved. DETAILED DESCRIPTION

[0024] In the embodiments of the present invention, if the specific conditions are not specified, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. Raw materials of different manufacturers and models do not affect the implementation of the technical solution of the present invention and the realization of the technical effects.

[0025] Example 1

[0026] The method for preparing the aramid yarn of this embodiment includes the following steps:

[0027] (1) A linear aramid raw material formed by twisting aramid fibers is taken, surface treated with isocyanate, and the aramid raw material is fully immersed in an impregnation liquid containing the isocyanate, taken out and placed at 180° C., and dried for 1 minute to obtain a first intermediate product; wherein the aramid fiber is poly(p-phenylene terephthalamide) fiber, and the twist of the linear aramid raw material formed by twisting is 30 tpm. The impregnation liquid is an ethylene glycol solution of toluene diisocyanate. The weight percentage of ethylene glycol in the impregnation liquid is 60%.

[0028] (2) The first intermediate product in step (1) is subjected to secondary surface treatment with a resin, the resin is heated and melted, and the first intermediate product is placed in the molten resin so that the resin covers the first intermediate product to obtain an aramid yarn. The resin is a polyethylene resin.

[0029] (3) The aramid yarn obtained in step (2) was cut into segments with a length of 30 mm.

[0030] The aramid yarn described in this embodiment can be applied to the field of concrete or mortar materials.

[0031] Example 2

[0032] The method for preparing the aramid yarn of this embodiment includes the following steps:

[0033] (1) A linear aramid raw material formed by twisting aramid fibers is taken, surface treated with isocyanate, and the aramid raw material is fully immersed in an impregnation liquid containing the isocyanate, taken out and placed at 240° C., and dried for 2 minutes to obtain a first intermediate product; wherein the aramid fiber is a modified poly(p-phenylene terephthalamide) fiber, and the twist of the linear aramid raw material formed by twisting is 100 tpm. The impregnation liquid is an ethylene glycol solution of hexamethylene diisocyanate. The weight percentage of ethylene glycol in the impregnation liquid is 70%.

[0034] (2) The first intermediate product in step (1) is subjected to secondary surface treatment with a resin, the resin is heated and melted, and the first intermediate product is placed in the molten resin so that the resin covers the first intermediate product to obtain an aramid yarn. The resin is a polypropylene resin.

[0035] (3) The aramid yarn obtained in step (2) was cut into segments with a length of 80 mm.

[0036] The aramid yarn described in this embodiment can be applied to the field of concrete or mortar materials.

[0037] Example 3

[0038] The method for preparing the aramid yarn of this embodiment includes the following steps:

[0039] (1) A linear aramid raw material formed by twisting aramid fibers is taken, surface treated with isocyanate, and the aramid raw material is fully immersed in an impregnation liquid containing the isocyanate, taken out and placed at 210° C., and dried for 3 minutes to obtain a first intermediate product; wherein the aramid fiber is poly(p-phenylene terephthalamide) fiber, and the twist of the linear aramid raw material formed by twisting is 80 tpm. The impregnation liquid is an ethylene glycol solution of toluene diisocyanate. The weight percentage of ethylene glycol in the impregnation liquid is 65%.

[0040] (2) The first intermediate product in step (1) is subjected to secondary surface treatment with a resin, the resin is heated and melted, and the first intermediate product is placed in the molten resin so that the resin covers the first intermediate product to obtain an aramid yarn. The resin is a polyvinyl alcohol resin.

[0041] (3) The aramid yarn obtained in step (2) was cut into segments with a length of 80 mm.

[0042] The aramid yarn described in this embodiment can be applied to the field of concrete or mortar materials.

[0043] Example 4

[0044] The method for preparing the aramid yarn of this embodiment includes the following steps:

[0045] (1) A linear aramid raw material formed by twisting aramid fibers is taken, surface treated with isocyanate, and the aramid raw material is fully immersed in an impregnation liquid containing the isocyanate, taken out and placed at 220° C., and dried for 1 minute to obtain a first intermediate product; wherein the aramid fiber is poly(p-phenylene terephthalamide) fiber, and the twist of the linear aramid raw material formed by twisting is 80 tpm. The impregnation liquid is an ethylene glycol solution of toluene diisocyanate and hexamethylene diisocyanate mixed in a weight ratio of 1:3. The weight percentage of ethylene glycol in the impregnation liquid is 65%.

[0046] (2) The first intermediate product in step (1) is subjected to secondary surface treatment with a resin, the resin is heated and melted, and the first intermediate product is placed in the molten resin so that the resin covers the first intermediate product to obtain an aramid yarn. The resin is a polyethylene resin.

[0047] (3) The aramid yarn obtained in step (2) was cut into segments with a length of 100 mm.

[0048] The aramid yarn described in this embodiment can be applied to the field of concrete or mortar materials.

[0049] Example 5

[0050] The preparation method of the aramid yarn of this embodiment is the same as that of Embodiment 4, except that in step (1), the impregnation liquid is an ethylene glycol solution of toluene diisocyanate and hexamethylene diisocyanate mixed in a weight ratio of 1:4.

[0051] Example 6

[0052] The preparation method of the aramid yarn of this embodiment is the same as that of Embodiment 4, except that in step (1), the impregnation liquid is an ethylene glycol solution of toluene diisocyanate and hexamethylene diisocyanate mixed in a weight ratio of 1:2.

[0053] Comparative Example 1

[0054] The aramid raw material of this comparative example is the aramid raw material of Example 4, which is cut into segments with a length of 100 mm.

[0055] Comparative Example 2

[0056] The aramid yarn of this comparative example is prepared using the same raw materials as those of Example 4 and the same method, with the only difference being that the step of surface treatment with isocyanate is omitted and the aramid raw material is directly subjected to secondary surface treatment with resin.

[0057] Comparative Example 3

[0058] The aramid yarn of this comparative example is prepared using the same raw materials and the same method as that of Example 4, with the only difference being that the step of performing secondary surface treatment with resin is omitted.

[0059] Effect comparison ratio

[0060] In order to verify the technical effect of the aramid yarn described in the present invention, the following tests were conducted:

[0061] Take the aramid yarns prepared in Examples 1-6 and Comparative Examples 1-3, cut them into 30 mm pieces, add them into cement, and test the compressive strength and flexural strength. Wherein, the volume content of the aramid yarn is 0.02%. The test method refers to the standard GB175-2007 "General Portland Cement" to measure the compressive strength and flexural strength of cement. Taking the test result of Comparative Example 1 as 1, calculate the relative compressive strength and relative flexural strength of cement respectively; the relative compressive strength is the actual value of the compressive strength divided by the actual value of the compressive strength of Comparative Example 1; the relative flexural strength is the actual value of the flexural strength divided by the actual value of the flexural strength of Comparative Example 1.

[0062] After experimentation, the results are as follows:

[0063] Group Relative compressive strength Relative flexural strength Example 1 1.058 1.126 Example 2 1.036 1.146 Example 3 1.065 1.228 Example 4 1.095 1.270 Example 5 1.072 1.219 Example 6 1.069 1.211 Comparative Example 1 1 1 Comparative Example 2 1.003 1.015 Comparative Example 3 1.013 1.025

[0064] It can be seen from the above results that the aramid yarns of Examples 1-6 are added to cement, and the obtained cement is significantly better than that of Comparative Examples 1-3 in terms of compressive strength and flexural strength.

[0065] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A method for preparing an aramid yarn, characterized in that: The steps include: (1) taking a linear aramid raw material formed by twisting aramid fibers, and performing surface treatment with isocyanate to obtain a first intermediate product, wherein the isocyanate is toluene diisocyanate and hexamethylene diisocyanate; (2) subjecting the first intermediate product in step (1) to a secondary surface treatment using a resin to obtain an aramid yarn; The resin is one or more of polyethylene resin, polypropylene resin and polyvinyl alcohol resin; The secondary surface treatment comprises the following steps: heating and melting the resin, placing the first intermediate product in the molten resin, and allowing the resin to cover the first intermediate product.

2. The method for preparing aramid yarn according to claim 1, characterized in that: In step (1), the surface treatment comprises the following steps: dipping or coating the isocyanate on the surface of the aramid raw material.

3. The method for preparing aramid yarn according to claim 1, characterized in that: In step (1), the aramid fiber is poly(p-phenylene terephthalamide) fiber or modified poly(p-phenylene terephthalamide) fiber.

4. The method for preparing aramid yarn according to claim 1, characterized in that: The twist of the linear aramid raw material formed by twisting in step (1) is 30-100 tpm.

5. The method for preparing aramid yarn according to claim 1, characterized in that: The method further comprises cutting the aramid yarn obtained in step (2) into segments with a length of 30-100 mm.

6. Aramid yarn prepared by the method for preparing aramid yarn according to any one of claims 1 to 5.

7. Use of the aramid yarn according to claim 6 in the field of concrete or mortar materials.