POLYTETRAFLUOROETHYLENE COMPOSITE FILTER MATERIAL AND PREPARATION METHOD AND USES THEREOF

Abstract

The present invention relates to the field of air filtration, in particular to a polytetrafluoroethylene composite filter material and a preparation method and uses thereof. The polytetrafluoroethylene composite filter material comprises a support layer and a polytetrafluoroethylene microporous membrane layer, and the support layer and the polytetrafluoroethylene microporous membrane layer are compounded by an adhesive, wherein the adhesive comprises a two-component polyurethane adhesive, a pore forming agent and an inorganic filler. The present invention adopts a two-component solvent-free polyurethane adhesive, and by adding a low-temperature pore forming agent and an inorganic filler, the pore forming agent forms an irregular pore channel structure at the bonding interface during curing, and the inorganic filler prevents the adhesive from entering the micropores of the polytetrafluoroethylene membrane, so that the air permeability and filtration efficiency of the polytetrafluoroethylene microporous membrane are not affected after compounding; and the prepared polytetrafluoroethylene composite filter material has good air permeability, high peel strength, good filtration efficiency and good barrier effect.

Claims

1. A polytetrafluoroethylene composite filter material, comprising a support layer and a polytetrafluoroethylene microporous membrane layer, the support layer and the polytetrafluoroethylene microporous membrane layer are compounded by an adhesive, wherein the adhesive comprises a two-component polyurethane adhesive, a pore forming agent and an inorganic filler.

2. The polytetrafluoroethylene composite filter material according to claim 1, wherein the support layer is one or more selected from polypropylene non-woven fabric, polyester non-woven fabric, polyethylene non-woven fabric and polyamide non-woven fabric.

3. The polytetrafluoroethylene composite filter material according to claim 1, wherein the support layer has a thickness of 30 to 50 μm, and an average pore diameter of 3 to 8 μm.

4. The polytetrafluoroethylene composite filter material according to claim 1, wherein the polytetrafluoroethylene microporous membrane layer has a thickness of 10 to 80 μm, an average pore diameter of 0.2 to 0.8 μm, and a porosity of 85% to 89%.

5. The polytetrafluoroethylene composite filter material according to claim 1, wherein the mass fraction of the pore forming agent in the adhesive is 2% to 5%; and/or the mass fraction of the inorganic filler in the adhesive is 3% to 8%.

6. The polytetrafluoroethylene composite filter material according to claim 1, wherein the two-component polyurethane adhesive is prepared by reacting raw materials including polyester polyol and isocyanate polyester polyol.

7. The polytetrafluoroethylene composite filter material according to claim 6, wherein the two-component polyurethane adhesive is prepared by reacting the polyester polyol and isocyanate polyester polyol under stirring at 25 to 30° C. for 2 to 4 h.

8. The polytetrafluoroethylene composite filter material according to claim 1, wherein the pore forming agent is one or more selected from polyethylene oxide, polystyrene microspheres and polymethylmethacrylate; and/or the inorganic filler is one or more selected from calcium carbonate, barium carbonate and magnesium carbonate.

9. The method for preparing polytetrafluoroethylene composite filter material according to claim 1, characterized by comprising the following steps: step 1: mixing a two-component polyurethane adhesive, a pore forming agent and an inorganic filler uniformly to obtain an adhesive; step 2: coating the adhesive obtained in step 1 uniformly on one side of the support layer with a coating amount of 1.5 to 2 g/m.sup.2; step 3: laminating the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane and performing pressurizing and heating treatment to bond them together, wherein the pressurizing and heating treatment is performed at a pressure of 1.5 Mpa to 3.2 MPa, and a temperature of 50 to 60° C.; step 4: curing the composite material obtained in step 3 at a temperature of 55 to 70° C. for 6 to 12 h to obtain the polytetrafluoroethylene composite filter material.

10. (canceled)

11. The polytetrafluoroethylene composite filter material according to claim 2, wherein the support layer has a thickness of 30 to 50 μm, and an average pore diameter of 3 to 8 μm.

12. The polytetrafluoroethylene composite filter material according to claim 2, wherein the polytetrafluoroethylene microporous membrane layer has a thickness of 10 to 80 μm, an average pore diameter of 0.2 to 0.8 μm, and a porosity of 85% to 89%.

13. The polytetrafluoroethylene composite filter material according to claim 3, wherein the polytetrafluoroethylene microporous membrane layer has a thickness of 10 to 80 μm, an average pore diameter of 0.2 to 0.8 μm, and a porosity of 85% to 89%.

14. The polytetrafluoroethylene composite filter material according to claim 2, wherein the mass fraction of the pore forming agent in the adhesive is 2% to 5%; and/or the mass fraction of the inorganic filler in the adhesive is 3% to 8%.

15. The polytetrafluoroethylene composite filter material according to claim 3, wherein the mass fraction of the pore forming agent in the adhesive is 2% to 5%; and/or the mass fraction of the inorganic filler in the adhesive is 3% to 8%.

16. The polytetrafluoroethylene composite filter material according to claim 4, wherein the mass fraction of the pore forming agent in the adhesive is 2% to 5%; and/or the mass fraction of the inorganic filler in the adhesive is 3% to 8%.

17. The polytetrafluoroethylene composite filter material according to claim 2, wherein the two-component polyurethane adhesive is prepared by reacting raw materials including polyester polyol and isocyanate polyester polyol; the mass ratio of the polyester polyol to the isocyanate polyester polyol is (0.8 to 1.4):1; and the polyester polyol is prepared from raw materials including 20 to 30 parts by weight of adipic acid, 25 to 35 parts by weight of sebacic acid, 5 to 20 parts by weight of 1,2-propanediol, 15 to 30 parts by weight of butanediol and 25 to 40 parts by weight of diethylene glycol by esterification reaction at 140 to 160° C. for 2 to 4 h and polycondensation reaction at 200 to 220° C. for 1 to 3 h, and/or, the isocyanate polyester polyol is prepared by reacting raw materials including 10 to 15 parts by weight of polybutylene adipate, 20 to 35 parts by weight of polypropylene glycol and 15 to 25 parts by weight of phenylenedimethylene diisocyanate at 70 to 90° C. for 3 to 5 h.

18. The polytetrafluoroethylene composite filter material according to claim 3, wherein the two-component polyurethane adhesive is prepared by reacting raw materials including polyester polyol and isocyanate polyester polyol; the mass ratio of the polyester polyol to the isocyanate polyester polyol is (0.8 to 1.4):1; and the polyester polyol is prepared from raw materials including 20 to 30 parts by weight of adipic acid, 25 to 35 parts by weight of sebacic acid, 5 to 20 parts by weight of 1,2-propanediol, 15 to 30 parts by weight of butanediol and 25 to 40 parts by weight of diethylene glycol by esterification reaction at 140 to 160° C. for 2 to 4 h and polycondensation reaction at 200 to 220° C. for 1 to 3 h, and/or, the isocyanate polyester polyol is prepared by reacting raw materials including 10 to 15 parts by weight of polybutylene adipate, 20 to 35 parts by weight of polypropylene glycol and 15 to 25 parts by weight of phenylenedimethylene diisocyanate at 70 to 90° C. for 3 to 5 h.

19. The polytetrafluoroethylene composite filter material according to claim 6, wherein the mass ratio of the polyester polyol to the isocyanate polyester polyol is (0.8 to 1.4):1.

20. The polytetrafluoroethylene composite filter material according to claim 6, wherein the polyester polyol is prepared from raw materials including 20 to 30 parts by weight of adipic acid, 25 to 35 parts by weight of sebacic acid, 5 to 20 parts by weight of 1,2-propanediol, 15 to 30 parts by weight of butanediol and 25 to 40 parts by weight of diethylene glycol by esterification reaction at 140 to 160° C. for 2 to 4 h and polycondensation reaction at 200 to 220° C. for 1 to 3 h, and/or, the isocyanate polyester polyol is prepared by reacting raw materials including 10 to 15 parts by weight of polybutylene adipate, 20 to 35 parts by weight of polypropylene glycol and 15 to 25 parts by weight of phenylenedimethylene diisocyanate at 70 to 90° C. for 3 to 5 h.

What is claimed is:

1. A polytetrafluoroethylene composite filter material, comprising a support layer and a polytetrafluoroethylene microporous membrane layer, the support layer and the polytetrafluoroethylene microporous membrane layer are compounded by an adhesive, wherein the adhesive comprises a two-component polyurethane adhesive, a pore forming agent and an inorganic filler.

2. The polytetrafluoroethylene composite filter material according to claim 1, wherein the support layer is one or more selected from polypropylene non-woven fabric, polyester non-woven fabric, polyethylene non-woven fabric and polyamide non-woven fabric.

3. The polytetrafluoroethylene composite filter material according to claim 1 or 2, wherein the support layer has a thickness of 30 to 50 μm, and an average pore diameter of 3 to 8 μm.

4. The polytetrafluoroethylene composite filter material according to any one of claims 1 to 3, wherein the polytetrafluoroethylene microporous membrane layer has a thickness of 10 to 80 μm, an average pore diameter of 0.2 to 0.8 μm, and a porosity of 85% to 89%.

5. The polytetrafluoroethylene composite filter material according to any one of claims 1 to 4, wherein the mass fraction of the pore forming agent in the adhesive is 2% to 5%; and/or the mass fraction of the inorganic filler in the adhesive is 3% to 8%.

6. The polytetrafluoroethylene composite filter material according to any one of claims 1 to 5, wherein the two-component polyurethane adhesive is prepared by reacting raw materials including polyester polyol and isocyanate polyester polyol; preferably, the mass ratio of the polyester polyol to the isocyanate polyester polyol is (0.8 to 1.4):1; more preferably, the polyester polyol is prepared from raw materials including 20 to 30 parts by weight of adipic acid, 25 to 35 parts by weight of sebacic acid, 5 to 20 parts by weight of 1,2-propanediol, 15 to 30 parts by weight of butanediol and 25 to 40 parts by weight of diethylene glycol by esterification reaction at 140 to 160° C. for 2 to 4 h and polycondensation reaction at 200 to 220° C. for 1 to 3 h, and/or, the isocyanate polyester polyol is prepared by reacting raw materials including 10 to 15 parts by weight of polybutylene adipate, 20 to 35 parts by weight of polypropylene glycol and 15 to 25 parts by weight of phenylenedimethylene diisocyanate at 70 to 90° C. for 3 to 5 h.

7. The polytetrafluoroethylene composite filter material according to claim 6, wherein the two-component polyurethane adhesive is prepared by reacting the polyester polyol and isocyanate polyester polyol under stirring at 25 to 30° C. for 2 to 4 h.

8. The polytetrafluoroethylene composite filter material according to any one of claims 1 to 7, wherein the pore forming agent is one or more selected from polyethylene oxide, polystyrene microspheres and polymethylmethacrylate; and/or the inorganic filler is one or more selected from calcium carbonate, barium carbonate and magnesium carbonate.

9. The method for preparing polytetrafluoroethylene composite filter material according to any one of claims 1 to 8, characterized by comprising the following steps: step 1: mixing a two-component polyurethane adhesive, a pore forming agent and an inorganic filler uniformly to obtain an adhesive; step 2: coating the adhesive obtained in step 1 uniformly on one side of the support layer with a coating amount of 1.5 to 2 g/m.sup.2; step 3: laminating the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane and performing pressurizing and heating treatment to bond them together, wherein the pressurizing and heating treatment is performed at a pressure of 1.5 Mpa to 3.2 MPa, and a temperature of 50 to 60° C.; step 4: curing the composite material obtained in step 3 at a temperature of 55 to 70° C. for 6 to 12 h to obtain the polytetrafluoroethylene composite filter material.

10. Use of the polytetrafluoroethylene composite filter material according to any one of claims 1 to 8 or the polytetrafluoroethylene composite filter material prepared by the preparation method according to claim 9 in air purification equipment or masks.

Description

EXAMPLE 1

[0028] Example 1 provides a polytetrafluoroethylene composite filter material, which comprises a support layer and a polytetrafluoroethylene layer, the support layer is made of polypropylene non-woven fabric, and has a thickness of 36 μm and an average pore diameter of 4.3 μm; and the polytetrafluoroethylene microporous membrane layer has a thickness of 25 μm, an average pore diameter of 0.31 μm and a porosity of 86%. The support layer and the polytetrafluoroethylene layer are compounded by an adhesive, and the adhesive comprises a two-component polyurethane adhesive, polystyrene and barium carbonate in a mass ratio of 92.2:3.6:4.2.

[0029] The method for preparing the polytetrafluoroethylene composite filter material described in the present Example specifically comprises the following steps:

[0030] (1) 20 parts by weight of adipic acid, 25 parts by weight of sebacic acid, 5 parts by weight of 1,2-propanediol, 15 parts by weight of butanediol and 25 parts by weight of diethylene glycol were esterified at 140° C. for 2 h, and then subjected to polycondensation at 200° C. for 1 h to obtain polyester polyol A; 13 parts by weight of polybutylene adipate, 25 parts by weight of polypropylene glycol and 18 parts by weight of phenylenedimethylene diisocyanate were reacted at 75° C. for 3.5 h to obtain isocyanate polyester polyol B;

[0031] (2) the polyester polyol A and isocyanate polyester polyol B with a mass ratio of 1:1 were reacted under stirring at 25° C. for 3 h to obtain the two-component polyurethane adhesive;

[0032] (3) the two-component polyurethane adhesive, polystyrene and barium carbonate were mixed uniformly to obtain an adhesive;

[0033] (4) the adhesive was coated uniformly on one side of the support layer with a coating amount of 1.6 g/m.sup.2;

[0034] (5) the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane were laminated and subjected to pressurizing and heating treatment under a pressure of 2.1 Mpa and a temperature of 55° C. to bond them together;

[0035] (6) the composite material obtained in step (5) was cured at 58° C. for 10 h to obtain the polytetrafluoroethylene composite filter material of the present Example.

EXAMPLE 2

[0036] Example 2 provides a polytetrafluoroethylene composite filter material, which comprises a support layer and a polytetrafluoroethylene layer, wherein the support layer is made of polyethylene non-woven fabric and has a thickness of 38 μm and an average pore diameter of 4.9 μm, and the polytetrafluoroethylene microporous membrane layer has a thickness of 25 μm, an average pore diameter of 0.31 μm and a porosity of 86%. The support layer and the polytetrafluoroethylene layer are compounded by an adhesive, and the adhesive comprises a two-component polyurethane adhesive, polyethylene oxide and calcium carbonate in a mass ratio of 94.4:2.4:3.2.

[0037] The method for preparing the polytetrafluoroethylene composite filter material described in the present Example specifically comprises the following steps:

[0038] (1) 24 parts by weight of adipic acid, 28 parts by weight of sebacic acid, 10 parts by weight of 1,2-propanediol, 15 parts by weight of butanediol and 32 parts by weight of diethylene glycol were esterified at 150° C. for 3 h, and then subjected to polycondensation at 200° C. for 2 h to obtain polyester polyol A; 12 parts by weight of polybutylene adipate, 30 parts by weight of polypropylene glycol and 20 parts by weight of phenylenedimethylene diisocyanate were reacted at 80° C. for 4 h to obtain isocyanate polyester polyol B;

[0039] (2) the polyester polyol A and isocyanate polyester polyol B with a mass ratio of 0.9:1 were reacted under stirring at 25° C. for 3 h to obtain the two-component polyurethane adhesive;

[0040] (3) the two-component polyurethane adhesive, polystyrene and barium carbonate were mixed uniformly to obtain the adhesive;

[0041] (4) the adhesive was coated uniformly on one side of the support layer with a coating amount of 1.6 g/m.sup.2;

[0042] (5) the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane were laminated, and subjected to pressurizing and heating treatment under a pressure of 1.7 Mpa and a temperature of 58° C. to bond them together;

[0043] (6) the composite material obtained in step (5) was cured at 62° C. for 8 h to obtain the polytetrafluoroethylene composite filter material of the present Example.

EXAMPLE 3

[0044] Example 3 provides a polytetrafluoroethylene composite filter material, which comprises a support layer and a polytetrafluoroethylene layer, wherein the support layer is made of polyamide non-woven fabric and has a thickness of 45 μm and an average pore diameter of 5.1 μm, and the polytetrafluoroethylene microporous membrane layer has a thickness of 25 μm, an average pore diameter of 0.31 μm and a porosity of 86%. The support layer and the polytetrafluoroethylene layer are compounded by an adhesive, and the adhesive comprises a two-component polyurethane adhesive, polystyrene and barium carbonate in a mass ratio of 92.2:3.6:4.2.

[0045] The method for preparing the polytetrafluoroethylene composite filter material in the present Example specifically comprises the following steps:

[0046] (1) 28 parts by weight of adipic acid, 30 parts by weight of sebacic acid, 8 parts by weight of 1,2-propanediol, 25 parts by weight of butanediol and 34 parts by weight of diethylene glycol were esterified at 160° C. for 4 h, and then subjected to polycondensation at 220° C. for 3 h to obtain polyester polyol A; 15 parts by weight of polybutylene adipate, 30 parts by weight of polypropylene glycol and 22 parts by weight of phenylenedimethylene diisocyanate were reacted at 80° C. for 4 h to obtain isocyanate polyester polyol B;

[0047] (2) the polyester polyol A and isocyanate polyester polyol B with a mass ratio of 0.9:1 were reacted under stirring at 25° C. for 3 h to obtain the two-component polyurethane adhesive;

[0048] (3) the two-component polyurethane adhesive, polystyrene and barium carbonate were mixed uniformly to obtain the adhesive;

[0049] (4) the adhesive was coated uniformly on one side of the support layer with a coating amount of 1.6g/m.sup.2;

[0050] (5) the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane were laminated, and subjected to pressurizing and heating treatment under a pressure of 1.7 Mpa and a temperature of 58° C. to bond them together;

[0051] (6) the composite material obtained in step (5) was cured at 62° C. for 8 h to obtain the polytetrafluoroethylene composite filter material of the present Example.

EXAMPLE 4

[0052] Example 4 provides a polytetrafluoroethylene composite filter material, which differs from Example 1 only in that: in the preparation method of polytetrafluoroethylene composite filter material described in Example 4, the step (1) was as follows: 10 parts by weight of adipic acid, 40 parts by weight of sebacic acid, 25 parts by weight of 1,2-propanediol, 10 parts by weight of butanediol and 25 parts by weight of diethylene glycol were esterified at 140° C. for 2 h, and then subjected to polycondensation at 200° C. for 1 h to obtain polyester polyol A; 5 parts by weight of polybutylene adipate, 35 parts by weight of polypropylene glycol and 10 parts by weight of phenylenedimethylene diisocyanate were reacted at 75° C. for 3.5 h to obtain isocyanate polyester polyol B.

COMPARATIVE EXAMPLE 1

[0053] Comparative Example 1 provides a polytetrafluoroethylene composite filter material, which differs from Example 1 only in that: the adhesive used in Comparative Example 1 is a conventional TPU adhesive.

COMPARATIVE EXAMPLE 2

[0054] Comparative Example 2 provides a polytetrafluoroethylene composite filter material, which comprises a support layer and a polytetrafluoroethylene layer, wherein the support layer is made of polypropylene non-woven fabric and has a thickness of 36 μm and an average pore diameter of 4.3 μm; and the polytetrafluoroethylene microporous membrane layer has a thickness of 25 μm, an average pore diameter of 0.31 μm and a porosity of 86%. The support layer and the polytetrafluoroethylene layer are compounded by an adhesive, and the adhesive is a two-component polyurethane adhesive.

[0055] The method for preparing the polytetrafluoroethylene composite filter material described in the present Comparative Example specifically comprises the follow steps:

[0056] (1) 20 parts by weight of adipic acid, 25 parts by weight of sebacic acid, 5 parts by weight of 1,2-propanediol, 15 parts by weight of butanediol and 25 parts by weight of diethylene glycol were esterified at 140° C. for 2 h, and then subjected to polycondensation at 200° C. for 1 h to obtain polyester polyol A; 13 parts by weight of polybutylene adipate, 25 parts by weight of polypropylene glycol and 18 parts by weight of phenylenedimethylene diisocyanate were reacted at 75° C. for 3.5 h to obtain isocyanate polyester polyol B;

[0057] (2) the polyester polyol A and isocyanate polyester polyol B with a mass ratio of 1:1 were reacted under stirring at 25° C. for 3 h to obtain the two-component polyurethane adhesive;

[0058] (3) the two-component polyurethane adhesive was coated uniformly on one side of the supporting layer with a coating amount of 1.6 g/m.sup.2;

[0059] (4) the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane were laminated, and subjected to pressurizing and heating treatment under a pressure of 2.1 Mpa and a temperature of 55° C. to bond them together;

[0060] (5) the composite material obtained in step (4) was cured at 58° C. for 10 h to obtain the polytetrafluoroethylene composite filter material of the present Comparative Example.

COMPARATIVE EXAMPLE 3

[0061] Comparative Example 3 provides a polytetrafluoroethylene composite filter material, which comprises a support layer and a polytetrafluoroethylene layer, wherein the support layer is made of polypropylene non-woven fabric and has a thickness of 36 μm and an average pore diameter of 4.3 μm; and the polytetrafluoroethylene microporous membrane layer has a thickness of 25 μm, an average pore diameter of 0.31 μm and a porosity of 86%.

[0062] The support layer and the polytetrafluoroethylene layer are compounded by an adhesive, and the adhesive comprises a two-component polyurethane adhesive and polystyrene in a mass ratio of 92.2:3.6.

[0063] The method for preparing the polytetrafluoroethylene composite filter material in the present Comparative Example specifically comprises the follow steps:

[0064] (1) 20 parts by weight of adipic acid, 25 parts by weight of sebacic acid, 5 parts by weight of 1,2-propanediol, 15 parts by weight of butanediol and 25 parts by weight of diethylene glycol were esterified at 140° C. for 2 h, and then subjected to polycondensation at 200° C. for 1 h to obtain polyester polyol A; 13 parts by weight of polybutylene adipate, 25 parts by weight of polypropylene glycol and 18 parts by weight of phenylenedimethylene diisocyanate were reacted at 75° C. for 3.5 h to obtain isocyanate polyester polyol B;

[0065] (2) the polyester polyol A and isocyanate polyester polyol B with a mass ratio of 1:1 were reacted under stirring at 25° C. for 3 h to obtain the two-component polyurethane adhesive;

[0066] (3) the two-component polyurethane adhesive and polystyrene were mixed uniformly to obtain an adhesive;

[0067] (4) the adhesive was coated uniformly on one side of the support layer with a coating amount of 1.6 g/m.sup.2;

[0068] (5) the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane were laminated, and subjected to pressurizing and heating treatment under a pressure of 2.1 Mpa and a temperature of 55° C. to bond them together;

[0069] (6) the composite material obtained in step (5) was cured at 58° C. for 10 h to obtain the polytetrafluoroethylene composite filter material of the present Comparative Example.

COMPARATIVE EXAMPLE 4

[0070] Comparative Example 4 provides a polytetrafluoroethylene composite filter material, which comprises a support layer and a polytetrafluoroethylene layer, wherein the support layer is made of polypropylene non-woven fabric and has a thickness of 36 μm and an average pore diameter of 4.3 μm; and the polytetrafluoroethylene microporous membrane layer has a thickness of 25 μm, an average pore diameter of 0.31 μm and a porosity of 86%. The support layer and the polytetrafluoroethylene layer are compounded by an adhesive, and the adhesive comprises a two-component polyurethane adhesive and barium carbonate in a mass ratio of 92.2:4.2.

[0071] The method for preparing the polytetrafluoroethylene composite filter material in the present Comparative Example specifically comprises the follow steps:

[0072] (1) 20 parts by weight of adipic acid, 25 parts by weight of sebacic acid, 5 parts by weight of 1,2-propanediol, 15 parts by weight of butanediol and 25 parts by weight of diethylene glycol were esterified at 140° C. for 2h, and then subjected to polycondensation at 200° C. for 1 h to obtain polyester polyol A; 13 parts by weight of polybutylene adipate, 25 parts by weight of polypropylene glycol and 18 parts by weight of phenylenedimethylene diisocyanate were reacted at 75° C. for 3.5 h to obtain isocyanate polyester polyol B;

[0073] (2) the polyester polyol A and isocyanate polyester polyol B with a mass ratio of 1:1 were reacted under stirring at 25° C. for 3 h to obtain the two-component polyurethane adhesive;

[0074] (3) the two-component polyurethane adhesive and barium carbonate were mixed uniformly to obtain an adhesive;

[0075] (4) the adhesive was coated uniformly on one side of the support layer with a coating amount of 1.6 g/m.sup.2;

[0076] (5) the adhesive coated surface of the support layer and the polytetrafluoroethylene microporous membrane were laminated, and subjected to pressurizing and heating treatment under a pressure of 2.1 Mpa and a temperature of 55° C. to bond them together;

[0077] (6) the composite material obtained in step (5) was cured at 58° C. for 10 h to obtain the polytetrafluoroethylene composite filter material of the present Comparative Example.

EXPERIMENTAL EXAMPLE

[0078] The performance of polytetrafluoroethylene composite filter materials provided in Examples 1 to 4 and Comparative Examples 1 to 4 were tested, and the test results were shown in Table 2, in which:

[0079] The air permeability was carried out according to GBT 1038-2000 “Plastics-Film and Sheeting-Determination of gas transmission”;

[0080] The peel strength test was carried out according to GB 8808-88 “Test method for peel force of flexible laminated plastics”;

[0081] The filtration efficiency test was carried out according to GB 2626-2019 “Respiratory protection Non-powered air purifying particle respirator”.

TABLE-US-00002 TABLE 2 Test results for the performances of polytetrafluoroethylene microporous membrane composite filter material Air permeability Filtration efficiency Peel strength Item (%) (%) (N) Example 1 95 99.6 2.6 Example 2 97 99.3 2.1 Example 3 96 99.3 2.5 Example 4 93 99.2 2.3 Comparative 88 98.5 1.7 Example 1 Comparative 85 98.5 2.2 Example 2 Comparative 90 98.7 2.4 Example 3 Comparative 93 98.9 2.3 Example 4

[0082] Although general description, specific embodiments and experiments have been used to describe the present invention in detail above, it is obvious to a person skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, all these modifications or improvements made without departing from the spirit of the present invention belong to the scope of the present invention.

INDUSTRIAL APPLICABILITY

[0083] The present invention provides a polytetrafluoroethylene composite filter material and a preparation method and uses thereof. The polytetrafluoroethylene composite filter material comprises a support layer and a polytetrafluoroethylene microporous membrane layer, and the support layer and the polytetrafluoroethylene microporous membrane layer are compounded by an adhesive, wherein the adhesive comprises a two-component polyurethane adhesive, a pore forming agent and an inorganic filler. The present invention adopts a two-component solvent-free polyurethane adhesive, and by adding a low-temperature pore forming agent and an inorganic filler, the pore forming agent forms an irregular pore channel structure at the bonding interface during curing, and the inorganic filler prevents the adhesive from entering the micropores of the polytetrafluoroethylene membrane, so that the air permeability and filtration efficiency of the polytetrafluoroethylene microporous membrane are not affected after compounding; and the prepared polytetrafluoroethylene composite filtration material has good air permeability, high peel strength, good filtration efficiency, good barrier effect, and good economic value and application prospect.