A method for producing glass fiber chopped strand mat

Abstract

This invention discloses a method for producing chopped glass fiber mat, belonging to the field of chopped glass fiber processing technology. The mat exhibits excellent appearance quality, with uniform glass fiber distribution, free of stains and impurities, and without fiber shedding. The method involves stirring, settling, filtering, and vacuuming a chopped glass fiber suspension, followed by spreading to impart a certain degree of softness. Low-molecular-weight polyamide hot-melt powder is then introduced, bonding the randomly distributed chopped glass fibers into a non-woven sheet structure. This results in rapid impregnation, a good hand feel, excellent mold adhesion, easy degassing, high strength, and non-directional properties, which is beneficial for subsequent processing. Due to the presence of long aliphatic carbon chains and polar amide groups in the structure of low-molecular-weight polyamide molecules, it is an excellent toughening and curing agent for epoxy resins, allowing for room temperature curing. No low-molecular-weight substances are released during curing, and the shrinkage rate is low.

Description

Technical Field

[0001] This invention belongs to the field of chopped glass fiber processing technology, and specifically relates to a method for producing chopped glass fiber mat. Background Technology

[0002] Fiberglass chopped strand mat is a sheet-like product made by bonding short, non-directionally chopped glass fibers together with a chemical binder. CN201710128005.6 discloses a production process for chopped fiberglass mat. Fiberglass chopped strand mat is a type of glass fiber product widely used in the composite materials industry, primarily for transparent fiberglass sheets and hand lay-up fiberglass products, and is generally made using powder binders. The performance of the powder binder directly determines the intrinsic properties of the fiberglass mat, such as tensile strength, flexibility, impregnation, styrene dissolution rate, and the dry and wet flexural strength and tensile strength of the resulting fiberglass products. However, chopped fiberglass mats generally suffer from low resistance to the impact of flowing resins and are prone to defects. Furthermore, the use of existing PP and PU binders leads to low mechanical properties, poor flexibility, and poor stability in epoxy fiberglass. Those skilled in the art urgently need to develop a production method for chopped fiberglass mat to meet current application market and performance requirements. Summary of the Invention

[0003] In view of this, the present invention provides a method for producing glass fiber chopped strand mat.

[0004] A method for producing chopped glass fiber mat includes the following steps: First, after opening and combing the chopped glass fibers, a dispersant, a thickener, and water are added to form a uniform suspension. The pH value is adjusted to 2.5–3, and after stirring, settling, filtration, and vacuuming, the suspension is laid on a mesh belt to obtain a unit area mass of 100–150 g / m². 2 The process involves four steps: 1) laying the base mat; 2) settling and spreading: chopped glass fibers are laid flat on the base mat via a settling chamber, and steam is used to spray the chopped glass fibers. Resin hot-melt powder is also sprayed at a mass ratio of 7-10% using a powder spreader. 3) The mesh belt carries the laid chopped glass fibers with added resin hot-melt powder out of the settling chamber. 4) drying, cooling, cutting, and winding: The chopped glass fibers with added resin hot-melt powder are dried to form the glass fiber mat. The mat is then cooled to room temperature, cut, and wound to obtain the final product.

[0005] Furthermore, in the first step, the chopped glass fiber is alkali-free chopped glass fiber with a chopped length of 30-50 mm and a fiber diameter of 11-13 μm.

[0006] Furthermore, in the third step, the resin hot melt powder is a low molecular weight polyamide hot melt powder with a molecular weight of 1000-1500.

[0007] Low molecular weight polyamide hot melt adhesives have outstanding advantages such as narrow melting range and fast curing speed, and have good adhesion and flexibility.

[0008] Furthermore, in the first step, the suspension contains 0.7-0.98% chopped glass fiber by mass, 0.3-0.4% dispersant by mass, and 0.5-1% thickener by mass.

[0009] Furthermore, in the second step, the temperature of the steam spray is 45-50°C, the spray flow rate is 6-8 mL / min, and the spray particle diameter is 20-32 μm.

[0010] Furthermore, the drying temperature in the fourth step is 150–185°C.

[0011] Furthermore, the chopped strand mat has a unit area mass of 100–150 g / m². 2 .

[0012] This invention discloses a method for producing chopped strand mat of glass fiber. The mat exhibits excellent appearance quality, with uniform glass fiber distribution, free of stains and impurities, and without any yarn shedding. The method involves stirring, settling, filtering, and vacuuming a chopped glass fiber suspension, followed by spreading to impart a certain degree of softness. Low-molecular-weight polyamide hot-melt powder is then introduced, causing the randomly distributed chopped glass fibers to bond into a non-woven sheet structure. This results in rapid impregnation, a good hand feel, excellent mold compatibility, easy degassing, high strength, and non-directional properties, which is beneficial for subsequent processing. The presence of long aliphatic carbon chains and polar amide groups in the low-molecular-weight polyamide molecule structure effectively toughens and cures the epoxy resin, allowing for room temperature curing with no release of low-molecular-weight substances and minimal shrinkage. Previously used PP adhesives and other similar products often lead to defects in epoxy fiberglass, such as low mechanical properties, poor flexibility, and poor stability. Detailed Implementation Example 1

[0013] Raw materials and equipment: Huachao New Materials' alkali-free chopped glass fiber raw material, chopped length 30mm, fiber diameter 11μm, LY-BX3200 glass fiber chopped strand mat production line; Aosheng 1000 molecular weight polyamide hot melt powder 650, thickener Jinshuiqiao YT4000 hydroxyethyl methyl cellulose, dispersant Sirbon Petrochemical isomeric deca-ol polyoxyethylene ether Riten P3.

[0014] The production method of chopped glass fiber mat includes the following steps: Step 1: After opening and combing the chopped glass fibers, a dispersant, a thickener, and water are added to form a uniform suspension. The suspension contains 0.7% chopped glass fibers, 0.3% dispersant, and 0.5% thickener. The pH is adjusted to 2.5. After stirring, settling, filtering, and vacuuming, the mixture is laid on a mesh belt to obtain a base mat with a unit area mass of 100 g / m². Step 2: Settling and spreading: The raw material chopped glass fibers are settling and spread evenly on a mesh belt through a settling chamber. On the base mat of the belt, chopped glass fibers are steam-sprayed at a temperature of 45℃ and a flow rate of 6mL / min, with a particle diameter of 20μm. Resin hot-melt powder is sprayed at a mass ratio of 7% using a powder spreader. In the third step, the chopped glass fibers with added resin hot-melt powder are conveyed out of the settling chamber by a conveyor belt. In the fourth step, drying, cooling, cutting, and winding, the chopped glass fibers with added resin hot-melt powder are dried at 150℃ to form the glass fiber mat. The mat is then cooled to room temperature, cut, and wound to obtain the final product. The chopped glass fibers can be laid flat on the conveyor belt with uniform thickness. The resin hot-melt powder can be evenly sprayed onto the chopped glass fibers laid on the conveyor belt before entering the drying oven for initial shaping. The drying oven should have a heat-insulating protective layer, be well-sealed, and have no significant heat leakage. The mat exiting the drying oven is cold-pressed and sent to a cooling device for further cooling. The air-cooling device should be well-sealed with no obvious air leakage, and should be able to achieve continuous winding without stopping the machine.

[0015] Product: 100g / m 2 The felt roll has straight edges, is tightly and evenly wound, and is free from defects such as oil spots, stains, holes, and clumps of raw fibers. The moisture content is 0.20%. The longitudinal and transverse tensile breaking strength is 168 N / 150 mm. The styrene solubility (23℃) is 143 s. The standard state bending strength of epoxy resin E51 laminate is 127.8 MPa. The wet state (boiled in distilled water for 2 hours) is 113.4 MPa. Example 2

[0016] Raw materials and equipment: Huachao New Materials' alkali-free chopped glass fiber raw material, chopped length 50mm, fiber diameter 13μm, LY-BX3200 glass fiber chopped strand mat production line; Zhongtong Chemical's 1500 molecular weight JTA polyamide hot melt powder, thickener Pengkai hydroxyethyl methyl cellulose EH, dispersant Sirbang Petrochemical fatty alcohol polyoxyethylene ether Riten A2 (200).

[0017] A method for producing chopped glass fiber mat includes the following steps: First, after opening and combing the chopped glass fibers, a dispersant, a thickener, and water are added to form a uniform suspension. The suspension contains 0.98% chopped glass fibers, 0.4% dispersant, and 1% thickener. The pH is adjusted to 3. After stirring, settling, filtering, and vacuuming, the mixture is laid on a mesh belt to obtain a unit area mass of 150 g / m². 2 The process involves four steps: 1) laying the base mat; 2) settling and spreading: The raw material, chopped glass fibers, is laid evenly on the base mat via a settling chamber. Steam spraying of the chopped glass fibers is then performed at 50℃, a flow rate of 8mL / min, and a particle diameter of 32μm. Resin hot-melt powder is sprayed at a mass ratio of 10% using a powder spreader. 3) The mesh belt then carries the laid-up chopped glass fibers with added resin hot-melt powder out of the settling chamber. 4) drying, cooling, cutting, and winding: The chopped glass fibers with added resin hot-melt powder are dried at 185℃ to form the glass fiber mat. The mat is then cooled to room temperature, cut, and wound to obtain the final product. The chopped glass fibers can be laid evenly on the mesh belt with uniform thickness. The resin hot-melt powder can be evenly sprayed onto the chopped glass fibers laid on the mesh belt before entering the drying oven for initial shaping. The drying oven should have a heat-insulating protective layer, be well-sealed, and have no significant heat leakage. The felt from the drying oven is cold-pressed into shape and then sent to an air-cooling device for further cooling. The air-cooling device should be well-sealed with no obvious air leakage, and should allow for continuous winding without stopping the machine.

[0018] Product: 150g / m 2 The felt roll has straight edges, is tightly and evenly wound, and is free from defects such as oil spots, stains, holes, and clumps of raw fibers. The moisture content is 0.18%. The longitudinal and transverse tensile breaking strength is 154 N / 150 mm. The styrene solubility (23℃) is 161 s. The standard state bending strength of epoxy resin E44 laminate is 123.6 MPa. The wet state (boiled in distilled water for 2 hours) is 111.8 MPa.

[0019] Note: Refer to GB / T17470-2007 Glass fiber chopped strand mat and continuous strand; the glass fiber content of the laminate is 35% by mass.

Claims

1. A method for producing chopped strand mat of glass fiber, characterized in that, Includes the following steps: Step 1: After opening and combing the chopped glass fibers, add dispersant, thickener, and water to form a uniform suspension. Adjust the pH to 2.5-3, then stir, settle, filter, and vacuum-seal the solution before spreading it on a conveyor belt to obtain a unit area mass of 100-150 g / m². 2 The base felt; Step 2: Settling and spreading: The chopped glass fibers are settled and spread evenly on the base mat of the mesh belt through a settling chamber. Steam spraying is used to spray the chopped glass fibers, and resin hot melt powder is sprayed at a mass ratio of 7-10% through a powder spreader. Step 3: The mesh belt conveys the spread chopped glass fibers with added resin hot melt powder out of the settling chamber; the resin hot melt powder is low molecular weight polyamide hot melt powder. Step 4: Drying, cooling, cutting, and winding: The chopped glass fibers with added resin hot melt powder are dried to form glass fiber chopped mat. The glass fiber chopped mat from the oven is then cooled to room temperature, and then cut and wound to obtain the final product.

2. The method for producing glass fiber chopped strand mat according to claim 1, characterized in that, In the first step, the chopped glass fiber is alkali-free chopped glass fiber with a chopped length of 30-50 mm and a fiber diameter of 11-13 μm.

3. The method for producing glass fiber chopped strand mat according to claim 1, characterized in that, In the first step, the suspension contains 0.7% to 0.98% chopped glass fiber by mass, 0.3% to 0.4% dispersant by mass, and 0.5% to 1% thickener by mass.

4. The method for producing glass fiber chopped strand mat according to claim 1, characterized in that, The second step involves steam spraying at a temperature of 45–50°C, a flow rate of 6–8 mL / min, and a particle diameter of 20–32 μm.

5. The method for producing glass fiber chopped strand mat according to claim 1, characterized in that, The drying temperature in the fourth step is 150–185°C.

6. The method for producing glass fiber chopped strand mat according to claim 1, characterized in that, The chopped strand mat has a unit area mass of 100-150 g / m². 2 .