A kind of fiber surface treatment impregnation system and preparation method thereof

Abstract

The present invention discloses a dipping system for fiber surface treatment and a preparation method thereof. The dipping system includes a one-bath dipping solution and a two-bath dipping solution. The one-bath dipping solution is prepared from raw materials including the following components: deionized water, water-soluble epoxy resin and blocked isocyanate; the two-bath dipping solution is prepared from raw materials including the following components: deionized water, anionic aqueous polyurethane dispersion, curing agent and rubber latex. Compared with treatment methods such as plasma, ultraviolet-induced grafting, and fluorination, the one-bath treatment of the present invention has the advantages of not harsh reaction conditions, simple equipment, and little damage to the fiber; compared with the RFL system and epoxy resin-latex system, the two-bath does not use substances such as resorcinol and formaldehyde that are harmful to the human body, and the bonding performance is better than the RFL dipping system, and is also better than other environmentally friendly systems. The dipping solution is stable and can be stored and used for a long time, and is convenient for industrial continuous production.

Description

Technical Field

[0001] The invention relates to the technical field of fiber-reinforced rubber composite materials, in particular to a fiber surface treatment impregnation system and a preparation method thereof. Background Art

[0002] Fibers are often used as reinforcing materials and are compounded with rubber. They are widely used in industrial products such as tires, conveyor belts, and hoses. With the development of science and technology, the demand for high-performance fibers such as polyester fibers and aramid fibers is increasing, and the requirements for the bonding performance between fibers and rubber are becoming more and more stringent. High-performance fibers have excellent performance in all aspects, but their surfaces are inert and have few active groups. Usually, the two-bath method is used to treat the fibers. Generally, one-bath treatment activates the fiber surface and produces active groups, and the second bath uses the traditional resorcinol-formaldehyde-latex (RFL) dipping system.

[0003] However, the traditional one-bath treatment methods such as plasma, ultraviolet-induced grafting, and fluorination have the disadvantages of harsh reaction conditions, complex equipment, and great damage to the fiber. The traditional two-bath treatment uses a resorcinol-formaldehyde-latex (RFL) dipping system, which contains resorcinol and formaldehyde, which are harmful to the human body.

[0004] Therefore, there is an urgent need for a fiber surface treatment dipping system that can achieve better fiber-rubber interface bonding strength than the RFL dipping system, while also solving the problems of toxicity caused by the use of resorcinol and formaldehyde, difficulty in long-term storage of the dipping solution, and harsh industrial conditions. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a fiber surface treatment dipping system and a preparation method thereof. The present invention adopts a two-bath method for the surface treatment of the fiber, wherein one bath is used to prepare the dipping solution with blocked isocyanate, water-soluble epoxy resin and deionized water. Compared with treatment methods such as plasma, ultraviolet-induced grafting, and fluorination, the one-bath treatment of the present invention has the advantages of not harsh reaction conditions, simple equipment, and little damage to the fiber. The two-bath uses anionic aqueous polyurethane dispersion and rubber latex as the main raw materials. Compared with the RFL system and epoxy resin-latex system, the present invention does not use substances such as resorcinol and formaldehyde that are harmful to the human body, and the bonding performance is better than the RFL dipping system. The dipping solution is stable and can be stored and used for a long time, and is convenient for industrial continuous production.

[0006] One of the purposes of the present invention is to provide a dipping system for fiber surface treatment.

[0007] The dipping system comprises a first-bath dipping solution and a second-bath dipping solution;

[0008] The one-bath dipping solution is prepared from raw materials including the following components, in parts by weight:

[0009] Deionized water 100 parts by weight;

[0010] 1 to 5 parts by weight of water-soluble epoxy resin; preferably 1 to 2 parts by weight;

[0011] 4 to 9 parts by weight of blocked isocyanate; preferably 7 to 8 parts by weight;

[0012] The second bath dipping solution is prepared from raw materials including the following components, in parts by weight:

[0013] Deionized water 100 parts by weight;

[0014] 10 to 40 parts by weight of anionic aqueous polyurethane dispersion; preferably 20 to 35 parts by weight;

[0015] 1 to 5 parts by weight of curing agent; preferably 2 to 3 parts by weight;

[0016] 60 to 90 parts by weight of rubber latex; preferably 70 to 85 parts by weight;

[0017] The solid content of the anionic aqueous polyurethane dispersion is 25% to 35%, preferably 29% to 31%.

[0018] In a preferred embodiment of the present invention,

[0019] The anionic aqueous polyurethane dispersion can be prepared by a method of the prior art; in the present invention, preferably according to the following steps:

[0020] (1) adding polyol, isocyanate and catalyst dibutyltin dilaurate in sequence to react and form a prepolymer;

[0021] (2) adding a carboxylic acid-type waterborne polyurethane chain extender and 1,4-butanediol to the prepolymer described in (1) to carry out a chain extension reaction;

[0022] (3) adding triethylamine to the solution after the reaction in (2) for neutralization, and then adding deionized water with stirring to prepare the anionic aqueous polyurethane dispersion.

[0023] in,

[0024] In step (1), the reaction temperature is preferably 60 to 70°C;

[0025] In step (2), the chain extension reaction temperature is preferably 65 to 75°C;

[0026] In step (3), the neutralization reaction temperature is preferably 45 to 55°C.

[0027] In a preferred embodiment of the present invention,

[0028] The polyol is at least one of polytetramethylene glycol, polypropylene glycol, polyethylene glycol, poly-ε-caprolactone glycol, and polycarbonate 1,6-hexanediol; preferably at least one of polytetramethylene glycol 2000, polypropylene glycol 2000, and polyethylene glycol 2000; and / or,

[0029] The isocyanate is isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate or hexamethylene diisocyanate; and / or,

[0030] The carboxylic acid type waterborne polyurethane chain extender is one of 2,2-dimethylol propionic acid and 2,2-dimethylol butyric acid.

[0031] In the above-mentioned method for preparing anionic aqueous polyurethane dispersion, the amount of raw materials used is preferably within the following range, and technicians can also adjust it according to actual conditions.

[0032] By weight:

[0033]

[0034] In a preferred embodiment of the present invention,

[0035] The water-soluble epoxy resin is at least one of sorbitol glycidyl ether, diphenol propane type epoxy resin, bisphenol A type liquid epoxy resin, trimethylolpropane glycidyl ether, tetraphenol ethane tetraglycidyl ether epoxy resin; and / or,

[0036] The blocked isocyanate is an isocyanate blocked with a blocking agent;

[0037] The isocyanate is at least one of trimethyl-1,6-hexamethylene diisocyanate, tetramethylene diisocyanate, tetramethyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate, and the blocking agent is at least one of caprolactam, butanone oxime, and phenol.

[0038] In a preferred embodiment of the present invention,

[0039] The curing agent is a blocked isocyanate or an amino resin;

[0040] The blocked isocyanate used as curing agent is the same as described above, namely:

[0041] The blocked isocyanate is an isocyanate blocked with a blocking agent;

[0042] The isocyanate is at least one of trimethyl-1,6-hexamethylene diisocyanate, tetramethylene diisocyanate, tetramethyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate, and the blocking agent is at least one of caprolactam, butanone oxime, and phenol;

[0043] The amino resin is preferably HMMM; and / or,

[0044] The solid content of the rubber latex is 20% to 40%, and the rubber latex is selected from at least one of butyl pyrrolidone latex, styrene butadiene latex, styrene butadiene pyrrolidone latex, chloroprene latex, and nitrile butadiene latex.

[0045] In a preferred embodiment of the present invention,

[0046] The fiber is one of polyester cord, aramid cord, ultra-high molecular weight polyethylene fiber cord or a mixed cord of two or more cords.

[0047] The second object of the present invention is to provide a method for preparing the dipping system of the first object of the present invention.

[0048] Said include:

[0049] The water-soluble epoxy resin is added into deionized water and stirred, and then the blocked isocyanate is added and stirred to obtain a first-bath dipping solution; the anionic waterborne polyurethane dispersion and curing agent are added into deionized water, and then the rubber latex is added and stirred to obtain a second-bath dipping solution.

[0050] The specific technical solutions of the present invention are as follows:

[0051] The method for preparing a two-bath dipping solution for improving the bonding between fiber and rubber of the present invention comprises the steps of:

[0052] A. Preparation of one-bath dipping solution: Add water-soluble epoxy resin into deionized water, stir evenly for 30 to 50 minutes at room temperature, then add blocked isocyanate, stir evenly for 1.5 hours at room temperature to obtain a uniform one-bath dipping solution.

[0053] B. Preparation of anionic waterborne polyurethane dispersion: dehydrate the polyol in vacuo at 105°C for 1.5h, cool to 65°C, add isocyanate, add dibutyltin dilaurate, react for 1h under nitrogen protection, heat to 70°C, add carboxylic acid type waterborne polyurethane chain extender and 1,4-butanediol, react for 2h, cool to 50°C, add triethylamine and react for 30min, finally add deionized water, stir at 1000r / min for 1h to prepare anionic waterborne polyurethane dispersion.

[0054] C. Preparation of two-bath dipping solution: Add the prepared anionic aqueous polyurethane dispersion into deionized water, add a curing agent, add rubber latex, and stir at room temperature for 2 hours to obtain a uniform and stable dipping solution.

[0055] The fiber is sequentially immersed in one or two baths of dipping solution for drying and curing. Experiments show that the best drying temperature is 100-150°C and the best curing temperature is 220-260°C. The amount of adhesive on the fiber is 4-7%.

[0056] The principle of the present invention is as follows:

[0057] The principle of the one-bath reaction is that NCO reacts with the fiber, and then epoxy reacts with isocyanate to activate the fiber surface, making it easier to react with the subsequent reaction dipping solution. The main principle of the two-bath is that in the formed interface layer, the cross-linked waterborne polyurethane forms a network structure, which can react with the fiber surface after the one-bath treatment, and the waterborne polyurethane can wrap the latex inside, and the latex particles can be co-vulcanized with the rubber. Moreover, the waterborne polyurethane is originally an adhesive, which has a certain bonding effect.

[0058] The beneficial effects of the present invention are as follows:

[0059] 1. The dipping solution of the present invention does not contain free resorcinol, formaldehyde and other substances harmful to the human body, and is all water-soluble and does not contain harmful organic solvents.

[0060] 2. The fiber passes through the two-bath dipping system of anionic water-based polyurethane dispersion latex, and its bonding effect exceeds that of the RFL system.

[0061] 3. The prepared dipping solution is stable, and the components of the dipping solution and the prepared dipping solution can be stored for a long time at room temperature. The dipping solution can be industrialized for production and can also be used for continuous processing of fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a rubber-attached diagram of the aramid cord after treatment in Example 1 of the present invention;

[0063] Figure 2 This is a rubber-attached diagram of the aramid cord after treatment in Example 2 of the present invention;

[0064] Figure 3 This is a diagram of the adhesive attachment of the sample of Example 1 of the present invention after the H extraction test;

[0065] Figure 4 This is a diagram of the adhesive attachment of the sample of Example 2 of the present invention after the H extraction test. DETAILED DESCRIPTION

[0066] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0067] The raw materials used in the examples are all conventional commercially available raw materials.

[0068] The anionic waterborne polyurethane dispersion was prepared by referring to the document "A highly-effective ionic liquid flame retardant towards fire-safety waterborne polyurethane (WPU) with excellent comprehensive performance".

[0069] Example 1

[0070] A waterborne polyurethane-latex two-bath dipping system for surface treatment of aramid cord, the production steps are as follows:

[0071] (1) Preparation of a one-bath dipping solution: 1.48 parts by weight of sorbitol glycidyl ether was added to 100 parts by weight of deionized water and stirred at room temperature for 30 minutes to obtain a uniform aqueous solution, and then 7.59 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate was added and stirred at room temperature for 1.5 hours to obtain a one-bath dipping solution.

[0072] (2) Preparation of anionic waterborne polyurethane dispersion: 20.4 parts by weight of polytetrahydrofuran ether glycol 2000 was dehydrated under vacuum at 105°C for 1.5 hours, cooled to 65°C, and 7.05 parts by weight of isophorone diisocyanate and 0.001 parts by weight of dibutyltin dilaurate were added to react for 1 hour to form a prepolymer. The temperature was raised to 70°C, 1.32 parts by weight of 2,2-dihydroxymethyl propionic acid and 0.24 parts by weight of 1,4-butanediol were added to react for 2 hours, cooled to 50°C, 1 part by weight of triethylamine was added to react for 30 minutes, and finally 100 parts by weight of deionized water was added and stirred at a speed of 1000 r / min for 1 hour to obtain a blue-light-emitting, uniform and stable anionic waterborne polyurethane dispersion with a solid content of 30%.

[0073] (3) Preparation of a second-bath dipping solution: 23.76 parts by weight of the prepared anionic aqueous polyurethane dispersion and 2.14 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate were added to 100 parts by weight of deionized water, and then 74.26 parts by weight of butylpyrrolidone latex were added and stirred at room temperature for 2 hours to obtain a second-bath dipping solution.

[0074] (4) Dipping treatment: The aramid cord is first placed in a first-bath dipping solution for dipping, and is immersed at room temperature for 3 minutes; then the dipped cord is placed in an oven at 120°C for drying for 10 minutes and cured at 230°C for 5 minutes. The dipped aramid cord is then placed in a second-bath dipping solution for dipping, and is immersed at room temperature for 3 minutes; then the dipped cord is placed in an oven at 120°C for drying for 10 minutes and cured at 250°C for 5 minutes, so that the dipping solution adheres to the surface of the aramid cord, thereby obtaining the dipped aramid cord.

[0075] (5) Preparation of test strips: Referring to the standard GB / T36795-2018, the standard rubber is completely coated on the dipped cord to prepare the extraction sample, and finally it is placed on a flat vulcanizer for vulcanization. The vulcanization temperature is 150 °C, the vulcanization pressure is 5 MPa, and the vulcanization time is 20 min. Figure 1 This is an electron microscope picture of the aramid cord of Example 1 after treatment. It can be seen that the fiber surface is evenly coated with glue and the fiber surface is smooth, indicating that the dipping solution system is evenly dispersed in the water, and the glue is well coated on the fiber surface, and the formed interface is evenly distributed. Figure 3 This is a picture of the dipped aramid cord in Example 1 after it is drawn out, indicating that a lot of rubber remains on the fiber surface after the rubber is drawn out from the fiber. The fiber treated with the second bath has the stress load transferred due to the existence of the interface, and the interface performance is improved, which shows that the composite bonding performance of the fiber and the rubber is improved after the second bath treatment.

[0076] Example 2

[0077] A waterborne polyurethane-latex two-bath dipping system for surface treatment of aramid cord, the production steps are as follows:

[0078] (1) Preparation of a one-bath dipping solution: 1.5 parts by weight of trimethylolpropane glycidyl ether was added to 100 parts by weight of deionized water and stirred at room temperature for 30 minutes to obtain a uniform aqueous solution, and then 7.7 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate was added and stirred at room temperature for 1.5 hours to obtain a one-bath dipping solution.

[0079] (2) Preparation of anionic waterborne polyurethane dispersion: 20.4 parts by weight of polypropylene glycol 2000 was dehydrated under vacuum at 105°C for 1.5 hours, cooled to 65°C, and 7.05 parts by weight of isophorone diisocyanate and 0.001 parts by weight of dibutyltin dilaurate were added to react for 1 hour to form a prepolymer. The temperature was raised to 70°C, 1.32 parts by weight of 2,2-dihydroxymethylbutyric acid and 0.24 parts by weight of 1,4-butanediol were added to react for 2 hours, cooled to 50°C, 1 part by weight of triethylamine was added to react for 30 minutes, and finally 100 parts by weight of deionized water was added and stirred at a speed of 1000 r / min for 1 hour to obtain a blue-light-emitting, uniform and stable anionic waterborne polyurethane dispersion with a solid content of 30%.

[0080] (3) Preparation of a second-bath dipping solution: 34.41 parts by weight of the prepared anionic aqueous polyurethane dispersion and 2.85 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate were added to 100 parts by weight of deionized water, and then 80.65 parts by weight of butylpyrrolidone latex were added and stirred at room temperature for 2 hours to obtain a second-bath dipping solution.

[0081] (4) Dipping treatment: The aramid cord is first placed in a first-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 230°C for 5 minutes. The dipped aramid cord is then placed in a second-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 250°C for 5 minutes, so that the dipping solution adheres to the surface of the aramid cord, thereby obtaining the dipped aramid cord.

[0082] (5) Preparation of test strips: Referring to the standard GB / T36795-2018, the standard rubber is completely coated on the dipped cord to prepare the extraction sample, and finally it is placed on a flat vulcanizer for vulcanization. The vulcanization temperature is 150 °C, the vulcanization pressure is 5 MPa, and the vulcanization time is 20 min. Figure 2 This is an electron microscope picture of the aramid cord of Example 2 after treatment. It can be seen that the fiber surface is evenly coated with glue and the fiber surface is smooth, which means that the dipping solution system is evenly dispersed in the water and has good adhesive on the fiber surface, and the formed interface is evenly distributed. Figure 4 This is a picture of the dipped aramid cord in Example 2 after it is pulled out, indicating that a lot of rubber remains on the fiber surface after the rubber is pulled out from the fiber. The fiber treated with the second bath has the stress load transferred due to the existence of the interface, and the interface performance is improved, which shows that the composite bonding performance of the fiber and the rubber is improved after the second bath treatment.

[0083] Example 3

[0084] A waterborne polyurethane-latex two-bath dipping system for surface treatment of aramid cord, the production steps are as follows:

[0085] (1) Preparation of a one-bath dipping solution: 1.48 parts by weight of sorbitol glycidyl ether was added to 100 parts by weight of deionized water and stirred at room temperature for 30 minutes to obtain a uniform aqueous solution, and then 7.59 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate was added and stirred at room temperature for 1.5 hours to obtain a one-bath dipping solution.

[0086] (2) Preparation of anionic waterborne polyurethane dispersion: 19.15 parts by weight of polytetrahydrofuran ether glycol 2000 was dehydrated under vacuum at 105°C for 1.5 hours, cooled to 65°C, and 7.44 parts by weight of diphenylmethane diisocyanate and 0.005 parts by weight of dibutyltin dilaurate were added to react for 1 hour to form a prepolymer. The temperature was raised to 70°C, 1.45 parts by weight of 2,2-dihydroxymethylpropionic acid and 0.88 parts by weight of 1,4-butanediol were added to react for 2 hours, the temperature was lowered to 50°C, 1.09 parts by weight of triethylamine was added to react for 30 minutes, and finally 100 parts by weight of deionized water was added and stirred at a speed of 1000 r / min for 1 hour to obtain a blue-light-emitting, uniform and stable anionic waterborne polyurethane dispersion, the solid content of which was 30%.

[0087] (3) Preparation of a second-bath dipping solution: 23.76 parts by weight of the prepared anionic aqueous polyurethane dispersion and 2.85 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate were added to 100 parts by weight of deionized water, and then 74.25 parts by weight of butylpyrrolidone latex were added and stirred at room temperature for 2 hours to obtain a second-bath dipping solution.

[0088] (4) Dipping treatment: The aramid cord is first placed in a first-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 230°C for 5 minutes. The dipped aramid cord is then placed in a second-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 250°C for 5 minutes, so that the dipping solution adheres to the surface of the aramid cord, thereby obtaining the dipped aramid cord.

[0089] (5) Preparation of test strips: Referring to the standard GB / T36795-2018, the standard rubber is completely coated on the dipped cord to prepare the extraction sample, and finally it is placed on a flat vulcanizer for vulcanization. The vulcanization temperature is 150 °C, the vulcanization pressure is 5 MPa, and the vulcanization time is 20 min.

[0090] Example 4

[0091] A waterborne polyurethane-latex two-bath dipping system for surface treatment of polyester cord, the production steps are as follows:

[0092] (1) Preparation of a one-bath dipping solution: 1.48 parts by weight of sorbitol glycidyl ether was added to 100 parts by weight of deionized water and stirred at room temperature for 30 minutes to obtain a uniform aqueous solution, and then 7.59 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate was added and stirred at room temperature for 1.5 hours to obtain a one-bath dipping solution.

[0093] (2) Preparation of anionic waterborne polyurethane dispersion: 15.80 parts by weight of polytetrahydrofuran ether glycol 2000 and 5 parts by weight of polypropylene glycol were vacuum dehydrated at 105°C for 1.5 hours, cooled to 65°C, and 5.63 parts by weight of toluene diisocyanate and 0.003 parts by weight of dibutyltin dilaurate were added to react for 1 hour to form a prepolymer. The temperature was raised to 70°C, 1.45 parts by weight of 2,2-dihydroxymethyl propionic acid and 1.04 parts by weight of 1,4-butanediol were added to react for 2 hours, cooled to 50°C, 1.09 parts of triethylamine were added to react for 30 minutes, and finally 100 parts by weight of deionized water were added and stirred at a speed of 1000 r / min for 1 hour to obtain a blue-light-emitting, uniform and stable anionic waterborne polyurethane dispersion with a solid content of 30%.

[0094] (3) Preparation of a second-bath dipping solution: 34.41 parts by weight of the prepared anionic aqueous polyurethane dispersion and 2.85 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate were added to 100 parts by weight of deionized water, and then 80.65 parts by weight of butylpyrrolidone latex were added and stirred at room temperature for 2 hours to obtain a second-bath dipping solution.

[0095] (4) Dipping treatment: The polyester cord is first placed in a first-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 230°C for 5 minutes. The dipped polyester cord is then first placed in a second-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 240°C for 5 minutes, so that the dipping solution adheres to the surface of the polyester cord, thereby obtaining the dipped polyester cord.

[0096] (5) Preparation of test strips: Referring to the standard GB / T36795-2018, the standard rubber is completely coated on the dipped cord to prepare the extraction sample, and finally it is placed on a flat vulcanizer for vulcanization. The vulcanization temperature is 150 °C, the vulcanization pressure is 5 MPa, and the vulcanization time is 20 min.

[0097] Example 5

[0098] A waterborne polyurethane-latex two-bath dipping system for surface treatment of polyester cord, the production steps are as follows:

[0099] (1) Preparation of a one-bath dipping solution: 1.48 parts by weight of sorbitol glycidyl ether was added to 100 parts by weight of deionized water and stirred at room temperature for 30 minutes to obtain a uniform aqueous solution, and then 7.59 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate was added and stirred at room temperature for 1.5 hours to obtain a one-bath dipping solution.

[0100] (2) Preparation of anionic waterborne polyurethane dispersion: 10.80 parts by weight of polytetrahydrofuran ether glycol 2000, 7 parts by weight of polypropylene glycol and 2 parts by weight of polyethylene glycol were vacuum dehydrated at 105°C for 1.5 hours, cooled to 65°C, and 5.63 parts by weight of toluene diisocyanate and 0.003 parts by weight of dibutyltin dilaurate were added to react for 1 hour to form a prepolymer. The temperature was raised to 70°C, 1.45 parts by weight of 2,2-dihydroxymethylpropionic acid and 1.04 parts by weight of 1,4-butanediol were added to react for 2 hours, cooled to 50°C, 1.09 parts of triethylamine were added to react for 30 minutes, and finally 100 parts by weight of deionized water were added and stirred at a speed of 1000 r / min for 1 hour to obtain a blue-light-emitting, uniform and stable anionic waterborne polyurethane dispersion with a solid content of 30%.

[0101] (3) Preparation of a second-bath dipping solution: 23.76 parts by weight of the prepared anionic aqueous polyurethane dispersion and 2.13 parts by weight of caprolactam-blocked 4,4'-diphenylmethane diisocyanate were added to 100 parts by weight of deionized water, and then 74.26 parts by weight of butylpyrrolidone latex were added and stirred at room temperature for 2 hours to obtain a second-bath dipping solution.

[0102] (4) Dipping treatment: The polyester cord is first placed in a first-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 230°C for 5 minutes, and then the dipped polyester cord is placed in a second-bath dipping solution for dipping, and is dipped at room temperature for 3 minutes; then the dipped cord is placed in an oven at 150°C for drying for 10 minutes and cured at 240°C for 5 minutes, so that the dipping solution adheres to the surface of the polyester cord, thereby obtaining the dipped polyester cord.

[0103] (5) Preparation of test strips: Referring to the standard GB / T36795-2018, the standard rubber is completely coated on the dipped cord to prepare the extraction sample, and finally it is placed on a flat vulcanizer for vulcanization. The vulcanization temperature is 150 °C, the vulcanization pressure is 5 MPa, and the vulcanization time is 20 min.

[0104] Comparative Example 1

[0105] Comparative Example 1 is a conventional RFL dipping system treatment of aramid cord, prepared as follows:

[0106] (1) Dipping treatment: The aramid cord impregnated with the traditional RFL dipping system can be used directly without dipping.

[0107] (2) Preparation of test specimens: Referring to the standard GB / T36795-2018, the standard rubber is completely coated on the dipped cord to prepare the extraction specimen, and finally it is placed on a flat vulcanizer for vulcanization at a vulcanization temperature of 150 °C, a vulcanization pressure of 5 MPa, and a vulcanization time of 20 min.

[0108] Comparative Example 2

[0109] Comparative Example 2 is a nano-reinforced environmentally friendly impregnation system for aramid cords, which is prepared as follows:

[0110] (1) Preparation of a one-bath dipping solution: Add 1 part by weight of sorbitol glycidyl ether to 100 parts by weight of deionized water, stir at room temperature for 15 minutes to obtain a uniform aqueous solution, then add 3 parts by weight of ε-caprolactam-terminated diphenylmethane diisocyanate and 2 parts by weight of phenol-terminated isophorone diisocyanate, stir at room temperature for 1 hour to obtain a one-bath dipping solution.

[0111] (2) Preparation of two-bath dipping solution: 6 parts by weight of attapulgite and 2 parts by weight of clay were added to 100 parts by weight of deionized water and stirred for 1.5 hours. 4 parts by weight of maleic anhydride grafted styrene-butadiene copolymer and 4 parts by weight of maleic anhydride grafted polyisoprene were added and stirred at room temperature for 30 minutes. 0.5 parts by weight of 4-lutidine and 1.5 parts by weight of dimethylaminodimethane as curing agent were added and stirred at room temperature for 2 hours. Finally, 90 parts by weight of butylpyridine latex and 60 parts by weight of nitrile latex were added and stirred for 5 hours to obtain a two-bath dipping solution.

[0112] (3) Dipping treatment: The aramid cord is first placed in a first-bath dipping solution for dipping, and is dipped at room temperature for 2 minutes; the dipped cord is then placed in a 120°C oven for drying for 5 minutes, and then the dipped cord is placed in a second-bath dipping solution for dipping, and is dipped at room temperature for 2 minutes; the dipped cord is then placed in a 150°C oven for drying for 5 minutes and cured at 230°C for 3 minutes, so that the dipping solution adheres to the surface of the fiber fabric, thereby obtaining the dipped aramid cord.

[0113] (4) Preparation of test strips: Referring to the standard GB / T2942-2009, the standard rubber is completely coated on the dipped cord to prepare the extraction sample, and finally it is placed on a flat vulcanizer for vulcanization. The vulcanization temperature is 136°C, the vulcanization pressure is 15 MPa, and the vulcanization time is 50 min.

[0114] The equipment used above are all conventional production equipment.

[0115] The comparison of the adhesive properties of the samples obtained in the embodiments of the present invention and the comparative examples is shown in Table 1:

[0116] Table 1 Adhesive properties of samples obtained from the embodiments of the present invention and comparative examples

[0117]

[0118] The material preparation and testing method of the embodiment of the present invention is mainly to prepare the H extraction sample according to the provisions of the national standard GB / T36795-2018.

[0119] The anionic aqueous polyurethane dispersion of the present invention has no precipitation after centrifugation at 3000 r / min for 15 minutes in a centrifuge, and can be considered to have a storage stability period of 6 months. In addition, the two-bath dipping solution after the anionic aqueous polyurethane dispersion is mixed with rubber latex can be stored for one week without change.

[0120] From the data in the above table, it can be seen that the fiber is impregnated with water-based polyurethane latex in two baths, which makes its bonding effect better than that of RFL system and other environmentally friendly systems. In addition, the impregnation solution is environmentally friendly and can be stably stored and used for a long time, which is convenient for industrial production.

Claims

1. A fiber surface treatment impregnation system, characterized in that The dipping system comprises a first-bath dipping solution and a second-bath dipping solution; The one-bath dipping solution is prepared from raw materials including the following components, in parts by weight: The solid content of the anionic aqueous polyurethane dispersion is 25% to 35%; The curing agent is a blocked isocyanate; The anionic aqueous polyurethane dispersion is prepared by a method comprising the following steps: (1) adding polyol, isocyanate and catalyst dibutyltin dilaurate in sequence to react and form a prepolymer; (2) adding a carboxylic acid-type waterborne polyurethane chain extender and 1,4-butanediol to the prepolymer obtained in step (1) to carry out a chain extension reaction; (3) adding triethylamine to the solution after the reaction in step (2) for neutralization reaction, adding deionized water and stirring to prepare the anionic aqueous polyurethane dispersion; In the preparation method of the anionic aqueous polyurethane dispersion, the amount of the raw materials is within the following range: By weight: The conditions for the dipping treatment using the fiber surface treatment dipping system include: soaking the fiber in a bath of dipping solution, drying and curing, the drying temperature is 100-150°C, and the curing temperature is 220-260°C; then soaking the fiber in a second bath of dipping solution, drying and curing again, the drying temperature is 100-150°C, and the curing temperature is 220-260°C.

2. The dipping system according to claim 1, characterized in that: The components of the one-bath dipping solution are measured by weight: Deionized water 100 parts by weight; 1 to 2 parts by weight of water-soluble epoxy resin; Blocked isocyanate 7-8 parts by weight.

3. The dipping system according to claim 1, characterized in that: The components of the second bath dipping solution are measured by weight:

4. The dipping system according to claim 1, characterized in that: The solid content of the anionic aqueous polyurethane dispersion is 29% to 31%.

5. The dipping system according to claim 1, characterized in that: The polyol is at least one of polytetramethylene glycol, polypropylene glycol, polyethylene glycol, poly-ε-caprolactone glycol, and polycarbonate 1,6-hexanediol; and / or, The isocyanate is isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate or hexamethylene diisocyanate; and / or, The carboxylic acid type waterborne polyurethane chain extender is one of 2,2-dimethylol propionic acid and 2,2-dimethylol butyric acid.

6. The dipping system according to claim 1, characterized in that: The water-soluble epoxy resin is at least one of sorbitol glycidyl ether, diphenol propane type epoxy resin, bisphenol A type liquid epoxy resin, trimethylolpropane glycidyl ether, tetraphenol ethane tetraglycidyl ether epoxy resin; and / or, The blocked isocyanate is an isocyanate blocked with a blocking agent; The isocyanate is at least one of trimethyl-1,6-hexamethylene diisocyanate, tetramethylene diisocyanate, tetramethyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate, and the blocking agent is at least one of caprolactam, butanone oxime, and phenol.

7. The dipping system according to claim 1, characterized in that: The solid content of the rubber latex is 20% to 40%, and the rubber latex is selected from at least one of butyl pyrrolidone latex, styrene butadiene latex, styrene butadiene pyrrolidone latex, chloroprene latex, and nitrile butadiene latex.

8. The dipping system according to claim 1, characterized in that: The fiber is one of polyester cord, aramid cord, ultra-high molecular weight polyethylene fiber cord or a mixed cord of two or more cords.

9. A method for preparing a dipping system as claimed in any one of claims 1 to 8, characterized in that The following steps are involved: Add water-soluble epoxy resin into deionized water and stir, then add blocked isocyanate and stir to obtain a one-bath dipping solution; Anionic waterborne polyurethane dispersion and curing agent are added into deionized water, and then rubber latex is added and stirred to obtain a second-bath dipping solution.

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