Preparation method of halogen-free and phosphorus-free flame-retardant glass mat laminate

Abstract

The invention relates to a preparation method of a halogen-free and phosphorus-free flame-retardant glass mat laminate. The method comprises the following steps: mixing a solvent, a curing agent, and an accelerator to prepare a curing accelerator liquid; then mixing phenolphthalein-type benzoxazine and a glycidyl ester-type epoxy resin; adding Mg(OH)2-coated g-C3N4 filler and aluminum hydroxide; mixing to obtain an adhesive; subjecting the adhesive to microwave irradiation to obtain a pretreated adhesive; treating a glass mat with boric acid to obtain an activated glass mat; impregnating the activated glass mat in the pretreated adhesive, baking to obtain a prepreg; and then cutting, stacking, and hot pressing to obtain the halogen-free and phosphorus-free flame-retardant glass mat laminate. The laminate can meet the requirements of being halogen-free, phosphorus-free, and flame-retardant, has a flame retardancy of up to UL94V0, is highly environmentally friendly, and has excellent mechanical processing performance. The laminate has good resistance to large-area thermal shock of a 1200°C melt after being treated at room temperature or low temperature, and has a good smoke suppression effect.

Description

Technical Field

[0001] The invention relates to a preparation method of a halogen-free and phosphorus-free flame-retardant glass felt laminate, belonging to the technical field of laminates. Background Art

[0002] In the formulation of halogen-free materials, phosphides are generally selected as flame retardants to replace existing halogen compounds. However, since the phosphorus content cannot be too high, it will result in insufficient heat resistance.

[0003] Currently, halogen-free laminates primarily utilize phosphorus-based flame retardants to replace brominated epoxy resins to achieve flame retardancy. However, phosphorus-based flame retardants can hydrolyze and lead to oxidation in rivers or lakes, creating another environmental issue. Therefore, based on environmental protection requirements, halogen-free and phosphorus-free flame-retardant laminates are the mainstream development.

[0004] For laminated boards, some special applications (melting workshops), in addition, the impact of flame particle flows, such as flame impact of combustion materials, physical impact of combustion materials, etc., will affect the flame resistance of the board under extreme conditions; there are also some boards that have been in extreme low temperature environments for a long time, and their own flame resistance will be significantly reduced; in addition, the smoke suppression depends on the added smoke suppressants (such as magnesium hydroxide, aluminum hydroxide, etc.). The amount of smoke suppressants added has an upper limit, and excessive addition will affect other properties of the board.

[0005] Based on this, in the field of halogen-free, phosphorus-free, flame-retardant laminates, developing a laminate that combines the above properties has certain market prospects. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate. The specific technical solution is as follows:

[0007] A method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate comprises the following steps:

[0008] Step 1: Mix magnesium hydroxide and acetone in a mass ratio of 1: (2-3), ultrasonically disperse for 10-15 minutes, remove acetone by filtration, and dry at a temperature of 110-120°C to obtain refined magnesium hydroxide; the purpose of refining magnesium hydroxide is to remove crystal water and remove impurities from the surface of magnesium hydroxide. Refined magnesium hydroxide, g-C3N4 powder, and acetone are mixed in a mass ratio of 10: (12-16): (150-200), ultrasonically dispersed, remove acetone, dry at a temperature of 60-65°C, and grind to obtain Mg(OH)2-coated g-C3N4 filler.

[0009] Step 2: Pour 200-250 parts by mass of solvent, 5-8 parts by mass of curing agent, and 0.5-1.1 parts by mass of accelerator into a stirring kettle and stir and disperse them to obtain a curing accelerating liquid; then pour 100 parts by mass of phenolphthalein type benzoxazine and 20-30 parts by mass of glycidyl ester type epoxy resin into the reactor, stir and disperse them to obtain a resin mixture; then add 20-30 parts by mass of Mg(OH)2 coated g-C3N4 filler to the resin mixture in batches and successively, stir and disperse them, and then add 3-5 parts by mass of aluminum hydroxide, stir and disperse them to obtain an adhesive.

[0010] Step 3: Transfer the adhesive to a microwave reactor, react for 25 to 30 minutes at a microwave power of 200 to 260 W, and stir for 20 to 30 minutes to obtain a pretreated adhesive.

[0011] Step 4: Immerse the glass felt in a boric acid solution with a mass fraction of 10-12%, perform ultrasonic treatment at a temperature of 75-80° C. for 30-40 minutes, take out the glass felt, and dry it to obtain an activated glass felt.

[0012] Step 5: Immerse the activated glass felt in the pretreated adhesive, apply glue, and then place it in an oven and bake it at a temperature of 155-165° C. for 5-6 minutes to obtain a prepreg.

[0013] Step 6: Cut and stack the prepregs and place them into a hot press for hot pressing.

[0014] Step 7: After the hot pressing is completed, the mixture is cooled to room temperature and taken out to obtain the halogen-free and phosphorus-free flame-retardant glass felt laminate.

[0015] As a further improvement, in step 1, the frequency of ultrasonic dispersion is 20 kHz and the power is 300-500 W.

[0016] In a further improvement, the solvent is one or more of acetone and butanone.

[0017] In a further improvement, the curing agent is dicyandiamide.

[0018] In a further improvement, the accelerator is 2-methylimidazole.

[0019] As a further improvement, in step 4, the frequency of ultrasonic treatment is 22-23 kHz and the power is 120-150 W.

[0020] As a further improvement, in step 6, the temperature in the hot press is increased to 205-215° C. by a gradient, the pressure is increased to 0.85-0.9 MPa by a gradient, and hot pressing is performed for 2 hours under the conditions of 205-215° C. and 0.85-0.9 MPa.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention effectively solves the problem of uneven distribution of components inside the resin by adding Mg(OH)2-coated g-C3N4 filler to the composite resin of phenolphthalein-type benzoxazine and glycidyl ester-type epoxy resin and irradiating the resin mixture with microwaves. The filler distribution tends to be uniform, and while improving the flame retardancy, the compatibility and reactivity between the filler and the resin are also improved, significantly improving the laminate's resistance to large-area thermal shock of a 1200°C melt after room temperature and low-temperature freezing treatment.

[0023] 2. The resin composition (pretreatment adhesive), prepreg and laminate of the present invention can achieve the requirements of halogen-free, phosphorus-free and flame retardant, with flame retardancy reaching UL94 V0 level, high environmental protection and excellent mechanical processing performance.

[0024] 3. The resin composition (pretreated adhesive) of the present invention has good smoke suppression effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a photo of the halogen-free and phosphorus-free flame-retardant glass mat laminate described in Example 1;

[0026] Figure 2 This is a photo of the halogen-free and phosphorus-free flame-retardant glass mat laminate described in Example 2;

[0027] Figure 3 This is a physical photograph of the halogen-free and phosphorus-free flame-retardant glass mat laminate described in Example 3. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] Example 1

[0030] Step 1. Mix magnesium hydroxide and acetone in a mass ratio of 1:2, and ultrasonically disperse for 10 minutes. The ultrasonic dispersion frequency is 20 kHz and the power is 300 W. Remove the acetone and dry at 120°C to obtain refined magnesium hydroxide. Mix refined magnesium hydroxide, g-C3N4 powder, and acetone in a mass ratio of 10:12:150, perform ultrasonic dispersion, remove the acetone, dry at 60°C, and grind to obtain Mg(OH)2-coated g-C3N4 filler.

[0031] Step 2: Pour 250 kg of acetone, 8 kg of dicyandiamide, and 1.1 kg of 2-methylimidazole into a stirring kettle and stir and disperse them to obtain a curing promoting liquid; then pour 100 kg of phenolphthalein-type benzoxazine and 30 kg of glycidyl ester-type epoxy resin into the reactor, stir and disperse them, and obtain a resin mixture; then add 30 kg of Mg(OH)2-coated g-C3N4 filler to the resin mixture in batches and successively, stir and disperse, and then add 5 kg of aluminum hydroxide, and stir and disperse to obtain an adhesive.

[0032] Step 3: Transfer the adhesive to a microwave reactor, react for 30 min at a microwave power of 260 W, and stir for 30 min to obtain a pretreated adhesive.

[0033] Step 4: Immerse the glass felt in a boric acid solution with a mass fraction of 12%, perform ultrasonic treatment at a temperature of 80° C. for 40 minutes, take out the glass felt, and dry it to obtain an activated glass felt; the ultrasonic treatment frequency is 23 kHz and the power is 150 W.

[0034] Step 5: Immerse the activated glass felt in the pre-treated adhesive, apply glue, and then place it in an oven and bake it at 165° C. for 6 minutes to obtain a prepreg.

[0035] Step 6: Cut and stack the prepregs, and place them in a hot press for hot pressing. The temperature in the hot press is increased to 205° C. and the pressure is increased to 0.85 MPa at a gradient, and hot pressing is performed at 205° C. and 0.85 MPa for 2 hours.

[0036] Step 7: After the hot pressing is completed, the mixture is cooled to room temperature and taken out to obtain the halogen-free and phosphorus-free flame-retardant glass mat laminate. See the actual photo for details. Figure 1 .

[0037] Example 2

[0038] Step 1. Mix magnesium hydroxide and acetone in a mass ratio of 1:2.6, and ultrasonically disperse for 13 minutes. The ultrasonic dispersion frequency is 20 kHz and the power is 350 W. Remove the acetone and dry at a temperature of 105 ° C to obtain refined magnesium hydroxide. Mix refined magnesium hydroxide, g-C3N4 powder, and acetone in a mass ratio of 10:15:150, perform ultrasonic dispersion, remove the acetone, dry at a temperature of 60 ° C, and grind to obtain Mg(OH)2-coated g-C3N4 filler.

[0039] Step 2: Pour 220 kg of acetone, 7 kg of dicyandiamide, and 1 kg of 2-methylimidazole into a stirring kettle and stir and disperse them to obtain a curing promoting liquid; then pour 100 kg of phenolphthalein-type benzoxazine and 25 kg of glycidyl ester-type epoxy resin into the reactor, stir and disperse them, and obtain a resin mixture; then add 28 kg of Mg(OH)2-coated g-C3N4 filler to the resin mixture in batches and successively, stir and disperse, and then add 5 kg of aluminum hydroxide, and stir and disperse to obtain an adhesive.

[0040] Step 3: Transfer the adhesive to a microwave reactor, react for 30 minutes at a microwave power of 230 W, and stir for 20 minutes to obtain a pretreated adhesive.

[0041] Step 4: Immerse the glass felt in a boric acid solution with a mass fraction of 11%, perform ultrasonic treatment at a temperature of 80° C. for 30 minutes, take out the glass felt, and dry it to obtain an activated glass felt; the ultrasonic treatment frequency is 22 kHz and the power is 150 W.

[0042] Step 5: Immerse the activated glass felt in the pre-treated adhesive, apply glue, and then place it in an oven and bake it at 160° C. for 5 minutes to obtain a prepreg.

[0043] Step 6: Cut and stack the prepregs, and place them in a hot press for hot pressing. The temperature in the hot press is gradually increased to 210° C., and the pressure is gradually increased to 0.87 MPa. Hot pressing is performed at 210° C. and 0.87 MPa for 2 hours.

[0044] Step 7: After the hot pressing is completed, the mixture is cooled to room temperature and taken out to obtain the halogen-free and phosphorus-free flame-retardant glass mat laminate. See the actual photo for details. Figure 2 .

[0045] Example 3

[0046] Step 1. Mix magnesium hydroxide and acetone in a mass ratio of 1:3, and ultrasonically disperse for 15 minutes. The ultrasonic dispersion frequency is 20 kHz and the power is 500 W. Remove the acetone and dry at a temperature of 110°C to obtain refined magnesium hydroxide. Mix refined magnesium hydroxide, g-C3N4 powder, and acetone in a mass ratio of 10:16:200, perform ultrasonic dispersion, remove the acetone, dry at a temperature of 65°C, and grind to obtain Mg(OH)2-coated g-C3N4 filler.

[0047] Step 2: Pour 200 kg of acetone, 5 kg of dicyandiamide, and 0.5 kg of 2-methylimidazole into a stirring kettle and stir and disperse them to obtain a curing promoting liquid; then pour 100 kg of phenolphthalein-type benzoxazine and 20 kg of glycidyl ester-type epoxy resin into the reactor, stir and disperse them, and obtain a resin mixture; then add 20 kg of Mg(OH)2-coated g-C3N4 filler to the resin mixture in batches and successively, stir and disperse them, and then add 3 kg of aluminum hydroxide, and stir and disperse them to obtain an adhesive.

[0048] Step 3: Transfer the adhesive to a microwave reactor, react for 25 min at a microwave power of 200 W, and stir for 20 min to obtain a pretreated adhesive.

[0049] Step 4: Immerse the glass felt in a boric acid solution with a mass fraction of 10%, perform ultrasonic treatment at a temperature of 75° C. for 30 minutes, take out the glass felt, and dry it to obtain an activated glass felt; the ultrasonic treatment frequency is 22 kHz and the power is 120 W.

[0050] Step 5: Immerse the activated glass felt in the pre-treated adhesive, apply glue, and then place it in an oven and bake it at 155° C. for 5 minutes to obtain a prepreg.

[0051] Step 6: Cut and stack the prepregs, and place them in a hot press for hot pressing. The temperature in the hot press is gradually increased to 215° C., and the pressure is gradually increased to 0.9 MPa. Hot pressing is performed at 215° C. and 0.9 MPa for 2 hours.

[0052] Step 7: After the hot pressing is completed, the mixture is cooled to room temperature and taken out to obtain the halogen-free and phosphorus-free flame-retardant glass mat laminate. See the actual photo for details. Figure 3 .

[0053] Comparative Example 1

[0054] Compared with Example 1, in this example, the Mg(OH)2-coated g-C3N4 filler used in Step 2 was replaced with refined magnesium hydroxide, and the rest remained unchanged; finally, a control plate 1 was obtained.

[0055] Comparative Example 2

[0056] Compared with Example 1, in this example, the Mg(OH)2-coated g-C3N4 filler used in step 2 was replaced with refined magnesium hydroxide and g-C3N4 powder grinding material (refined magnesium hydroxide and g-C3N4 powder were mixed in a mass ratio of 10:12 and then ground), and the rest remained unchanged; finally, the control plate 2 was obtained.

[0057] Comparative Example 3

[0058] Compared with Example 1, in this example, the Mg(OH)2-coated g-C3N4 filler used in Step 2 was replaced with g-C3N4 powder, and the rest remained unchanged; finally, a control plate 3 was obtained.

[0059] Comparative Example 4

[0060] Compared with Example 1, in this example, the Mg(OH)2-coated g-C3N4 filler used in step 2 was replaced with an Al(OH)3-coated g-C3N4 filler, and the rest remained unchanged; finally, a control plate 4 was obtained. Among them, the magnesium hydroxide in step 1 was replaced with aluminum hydroxide, and finally the Al(OH)3-coated g-C3N4 filler was obtained.

[0061] Comparative Example 5

[0062] Compared with Example 1, in this example, step 3 is not performed, that is, the adhesive is not reacted under microwaves. In step 5, the activated glass felt is directly immersed in the adhesive, and the rest remains unchanged; finally, a control board 5 is obtained.

[0063] Comparative Example 6

[0064] Compared with Example 1, in this example, step 4 is not performed, that is, the glass felt is not ultrasonically treated in the boric acid solution. In step 5, the glass felt is directly immersed in the pretreated adhesive, and the rest remains unchanged; finally, a control board 6 is obtained.

[0065] The properties of the laminates corresponding to Examples 1 to 3 and Comparative Examples 1 to 6 are shown in Table 1:

[0066] Table 1

[0067]

[0068] As shown in Table 1, g-C3N4 is a lightweight material and is not easy to add alone to the resin glue. For example, if it is directly added in Control Example 2, it is easy to cause uneven distribution of the filler, which not only fails to exert the relevant performance of the filler, but also causes interference. After g-C3N4 and magnesium hydroxide are treated, magnesium hydroxide is coated around g-C3N4 to form a composite powder, thereby solving the large-area agglomeration of the filler. In addition, the addition of Mg(OH)2-coated g-C3N4 filler can significantly improve the large-area thermal shock resistance of the laminate. Even if the laminate is treated at extremely low temperatures, it still has excellent large-area thermal shock resistance.

[0069] Investigation of Large-Area Melt Thermal Shock

[0070] 1. Cut the laminates corresponding to Examples 1 to 3 and Comparative Examples 1 to 6 into 50 cm × 50 cm sample plates, and then surround the sample plates with iron bars and tighten them. The purpose of the iron bars is to prevent the subsequent tin-copper alloy melt from flowing out.

[0071] 2. Liquid CO2 untreated group: Pour 1200°C tin-copper alloy melt onto the front of the sample plate and cover the entire surface. The thickness of the tin-copper alloy melt layer on the surface of the sample plate should be 3±0.5mm. After 10 minutes, cool and clean the sample plate in water. Observe the back of the sample plate for burn-through. If burn-through is detected, calculate the total burn-through area using the grid method. Burn-through rate = total burn-through area / area of ​​the sample plate.

[0072] 3. Immerse the sample plate with the iron bar in liquid carbon dioxide for 1 hour, then take it out and place it at room temperature for 30 minutes. Then pour 1200℃ tin-copper alloy melt on the front of the sample plate and cover the front of the sample plate. The thickness of the tin-copper alloy melt layer on the surface of the sample plate is 3±0.5mm. After 10 minutes, drop the sample plate into water to cool and clean it, and observe whether there is any back burn-through on the back of the sample plate. If there is any burn-through, use the grid method to calculate the total burn-through area. Burn-through rate = total burn-through area / area of ​​the sample plate.

[0073] Investigation on the Smoke Suppression Properties of Resins

[0074] The smoke suppression properties of the pretreated adhesive in Example 1, the adhesive, and the corresponding pretreated adhesives in Comparative Examples 1 to 4 were investigated. The smoke density Ds4 was tested according to ISO 5659. The results are shown in Table 2:

[0075] Table 2

[0076]

[0077]

[0078] It can be seen from Table 2 that the smoke suppression effect brought about by adding Mg(OH)2 coated g-C3N4 filler is better than that brought about by adding g-C3N4 or magnesium hydroxide alone.

[0079] In the above examples, the phenolphthalein-based benzoxazine was purchased from Jinan Shengquan Group Co., Ltd.; the glycidyl ester-based epoxy resin, a halogen-free and phosphorus-free resin, was purchased from Jinan Shengquan Group Co., Ltd.; and g-C3N4, a graphite-like carbon nitride, was purchased from Guangdong Shengke Biochemical Technology Co., Ltd.

[0080] "Large Area Melt Thermal Shock Investigation" mainly examines the plate's resistance to flame particle flow impact (such as the impact of burning materials).

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate, characterized in that: The following steps are involved: Step 1, magnesium hydroxide and acetone are mixed in a mass ratio of 1: (2-3), ultrasonically dispersed for 10-15 minutes, the acetone is removed, and the mixture is dried at a temperature of 110-120° C. to obtain refined magnesium hydroxide; refined magnesium hydroxide, g-C3N4 powder, and acetone are mixed in a mass ratio of 10: (12-16): (150-200), ultrasonically dispersed, the acetone is removed, the mixture is dried at a temperature of 60-65° C., and ground to obtain Mg(OH)2-coated g-C3N4 filler; Step 2, pouring 200-250 parts by mass of a solvent, 5-8 parts by mass of a curing agent, and 0.5-1.1 parts by mass of an accelerator into a stirred tank and stirring and dispersing them to obtain a curing accelerating liquid; then pouring 100 parts by mass of a phenolphthalein type benzoxazine and 20-30 parts by mass of a glycidyl ester type epoxy resin into the reactor, stirring and dispersing them to obtain a resin mixture; then adding 20-30 parts by mass of Mg(OH)2 coated g-C3N4 filler to the resin mixture in batches and successively, stirring and dispersing them, and then adding 3-5 parts by mass of aluminum hydroxide, stirring and dispersing them to obtain an adhesive; Step 3: transferring the adhesive to a microwave reactor, reacting for 25 to 30 minutes at a microwave power of 200 to 260 W, and stirring for 20 to 30 minutes to obtain a pretreated adhesive; Step 4, immersing the glass mat in a boric acid solution having a mass fraction of 10 to 12%, ultrasonically treating the glass mat at a temperature of 75 to 80° C. for 30 to 40 minutes, taking out the glass mat, and drying the glass mat to obtain an activated glass mat; Step 5: Dipping the activated glass mat in the pre-treated adhesive, scraping the adhesive, and then baking it in an oven at 155-165° C. for 5-6 minutes to obtain a prepreg; Step 6: Cut and stack the prepregs, and place them in a hot press for hot pressing; Step 7: After the hot pressing is completed, the mixture is cooled to room temperature and taken out to obtain the halogen-free and phosphorus-free flame-retardant glass felt laminate.

2. The method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate according to claim 1, characterized in that: In step 1, the frequency of ultrasonic dispersion is 20 kHz and the power is 300-500 W.

3. The method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate according to claim 1, characterized in that: The solvent is one or more of acetone and butanone.

4. The method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate according to claim 1, characterized in that: The curing agent is dicyandiamide.

5. The method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate according to claim 1, characterized in that: The accelerator is 2-methylimidazole.

6. The method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate according to claim 1, characterized in that: In step 4, the frequency of ultrasonic treatment is 22-23 kHz and the power is 120-150 W.

7. The method for preparing a halogen-free and phosphorus-free flame-retardant glass mat laminate according to claim 1, characterized in that: In step 6, the temperature in the hot press is increased to 205-215° C. using a gradient, the pressure is increased to 0.85-0.9 MPa using a gradient, and hot pressing is performed at 205-215° C. and 0.85-0.9 MPa for 2 hours.

Images