Moisture-resistant and heat-resistant PVC building membrane structure material and preparation method thereof

Abstract

The application provides a moisture and heat aging resistant PVC building film structure material and a preparation method thereof, the preparation method adopts fluorine-containing acrylic ester block copolymer to perform hydrophobic treatment on a fabric, and then a composite crosslinking agent composed of a mercapto silane coupling agent and a peroxide is added into a coated PVC slurry, so that the moisture and heat aging resistant PVC building film structure material is prepared; the PVC film structure material is prepared by using a coating method, so that the PVC film structure material has more excellent air tightness and hydrophobicity; and in a humid and hot environment, the fluorine-containing block copolymer with active groups (-OH and C=C) is easy to have a crosslinking reaction with a main crosslinking agent in the PVC coating under the assistance of a crosslinking aid, so that a crosslinking network structure is formed between the fiber and the PVC resin, the peeling performance is effectively improved while the tensile strength loss of the product is reduced; and the preparation process is simple, the product has high applicability, and the processed product has excellent moisture and heat aging resistance.

Description

Technical Field

[0001] This invention belongs to the field of building membrane composite materials technology, specifically relating to a moisture- and heat-resistant PVC building membrane structural material and its preparation method. Background Technology

[0002] Polyester fabric, as a structural reinforcement, has excellent mechanical properties and dimensional stability. It is often used as a skeleton material and combined with polyvinyl chloride resin to obtain PET fabric reinforced PVC building membrane structure material with a "sandwich" structure. Due to its strong engineering applicability and high cost performance, PVC membrane structure material is widely used in various fields such as transportation, construction, military industry, exhibition, sports and leisure.

[0003] However, under the influence of humid and hot environments, due to the exposed edges of the skeleton fabric, PVC building membrane structure materials made of conventional polyester fabric (without hydrophobic treatment) are extremely prone to the "wick effect" due to the capillary action of the fabric, resulting in a serious decline in their mechanical properties (such as peel strength, tensile strength, etc.). This greatly shortens the service life of membrane structure composite materials. Therefore, developing PVC building membrane structure materials with good resistance to humid and hot aging is one of the prerequisites for ensuring the durability design of fiber-reinforced resin matrix composites. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for preparing PVC building membrane structure material resistant to damp heat aging. The PVC building membrane structure material prepared by this method exhibits significantly reduced mechanical property loss when applied in a damp heat environment, and even shows an enhanced tensile strength.

[0005] A method for preparing a PVC building membrane structure material resistant to damp heat aging includes the following steps:

[0006] (1) Use a hydrophobic agent to treat the fabric with hydrophobicity;

[0007] (2) PVC paste is prepared using PVC paste resin, plasticizer, heat stabilizer and composite crosslinking agent as raw materials;

[0008] (3) The PVC slurry is coated on both sides of the fabric that has been treated with hydrophobicity, and then plasticized to obtain the moisture-resistant and heat-aging PVC building membrane structure material.

[0009] In step (1) of the above preparation method:

[0010] Preferably, the hydrophobic agent is a fluorinated acrylate block copolymer. More preferably, it is one or more of TG5573, TG5673, TG5671, and DH3602. Even more preferably, it is one or two of TG5573 and TG5673.

[0011] As a preferred option, the specific steps for hydrophobic treatment of the fabric are as follows:

[0012] After mixing the hydrophobic agent with deionized water, the fabric is unrolled and immersed in the mixture, then removed, dried, and shaped.

[0013] The volume ratio of hydrophobic agent to deionized water is (10-40):100, the padding time is 10-120s, the setting temperature is 130-180℃, and the setting time is 1-10min.

[0014] As a further preferred option, the volume ratio of hydrophobic agent to deionized water is (20-40):100, and the padding time is 20-120 s.

[0015] Preferably, the fabric has a weight of 366 g / m². 2 .

[0016] In step (2) of the above preparation method:

[0017] Preferably, the PVC slurry is prepared from the following components in parts by weight:

[0018] 80-100 parts of PVC paste resin

[0019] 55-80 parts of plasticizer

[0020] 2-4 parts heat stabilizer

[0021] 0.01 to 3 parts of composite crosslinking agent.

[0022] The above-mentioned PVC slurry is prepared by stirring and mixing PVC paste resin, plasticizer, heat stabilizer and composite crosslinking agent evenly.

[0023] As a further preferred embodiment, the PVC slurry is prepared from the following components in parts by weight:

[0024] 100 parts of PVC paste resin

[0025] 55-80 parts of plasticizer

[0026] 2-4 parts heat stabilizer

[0027] 0.01 to 3 parts of composite crosslinking agent.

[0028] As a further preferred option, the amount of composite crosslinking agent added is 0.1 to 3 parts per 100 parts of PVC paste resin.

[0029] Preferably, the composite crosslinking agent includes a primary crosslinking agent and a secondary crosslinking agent; wherein the primary crosslinking agent is a mercaptosilane coupling agent and the secondary crosslinking agent is a peroxide.

[0030] As a further preferred embodiment, the main crosslinking agent is selected from one or more of (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, and 3-mercaptopropyl(dimethoxy)silane. Even more preferably, it is selected from one or two of (3-mercaptopropyl)trimethoxysilane and (3-mercaptopropyl)triethoxysilane.

[0031] As a further preferred embodiment, the crosslinking agent is selected from one or more of tert-butyl peroxide, dicumyl peroxide, and bis-tert-butyl peroxide. Even more preferably, it is selected from one or two of dicumyl peroxide and bis-tert-butyl peroxide.

[0032] As a further preferred embodiment, the mass ratio of the main crosslinking agent to the co-crosslinking agent in the composite crosslinking agent is 1:(0.01-2). More preferably, it is 1:(0.1-1.5). Even more preferably, it is 1:(0.5-1.2).

[0033] Preferably, the plasticizer is one or both of diisononyl phthalate and n-butyl phthalate.

[0034] Preferably, the heat stabilizer is a barium-zinc composite stabilizer.

[0035] In step (3) of the above preparation method:

[0036] Preferably, when coating both sides of the fabric, the coating amount is 50–150 g / m². 2 .

[0037] Specifically, PVC slurry is applied to both sides of the fabric by roller coating, with a coating amount of 50–150 g / m². 2 .

[0038] Preferably, plasticizing includes pre-baking and plasticizing. The pre-baking temperature is 120℃~150℃ and the pre-baking time is 2~10min; the plasticizing temperature is 160~200℃ and the plasticizing time is 3~8min.

[0039] As a further preferred option, the pre-drying temperature is 120℃~140℃, and the pre-drying temperature is preferably 3~10min.

[0040] As a further preferred option, the plasticizing temperature is 160–190℃ and the plasticizing time is 3–5 min.

[0041] The preparation method of this invention involves treating the fabric with a hydrophobic agent, followed by coating with PVC slurry to obtain a PVC building membrane structure material. A composite crosslinking agent, with mercaptosilane coupling agent as the main crosslinking agent and peroxide as the co-crosslinking agent, is added to the PVC slurry. The main component of the hydrophobic agent is a fluorinated acrylate copolymer containing active groups. In a humid and hot environment, the active free radicals generated by the co-crosslinking agent cause the fluorinated acrylate block copolymer to generate active free radicals (such as C=C and -OH), which then undergo multiple crosslinking reactions with the active free radicals (such as sulfhydryl groups and silanol groups) generated by the hydrolyzed main crosslinking agent in the PVC coating. Ultimately, a stable covalent crosslinking network is formed between the PVC and polyester fibers, thereby reducing the loss of mechanical properties of the building membrane structure material due to humid and hot aging.

[0042] A PVC building membrane structure material resistant to damp heat aging is prepared by any of the preparation methods described above. This PVC building membrane structure material exhibits excellent resistance to damp heat aging.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The present invention discloses a method for preparing a PVC building membrane structure material resistant to damp heat aging. This method involves treating the fabric with a fluorinated acrylate block copolymer to create a hydrophobic coating, while simultaneously adding a composite crosslinking agent composed of a mercaptosilane coupling agent and a peroxide to the coated PVC slurry. The method also utilizes a coating process to prepare the PVC membrane structure material, resulting in superior airtightness and hydrophobic properties.

[0045] In humid and hot environments, fluorinated block copolymers with active groups (-OH and C=C) can be easily activated by co-crosslinking agents and rapidly crosslink with the main crosslinking agent in the PVC coating, thereby forming a crosslinked network structure at the fiber-PVC resin interface. This effectively enhances peel performance while reducing the loss of tensile strength. Moreover, this preparation process is simple, the product has high applicability, and the processed product has excellent resistance to humid and hot aging.

[0046] In addition, the dense structure formed by the PVC slurry on the fabric surface through molecular entanglement and cross-linking can reduce the diffusion of moisture inside the composite material to a certain extent, effectively reduce the wicking effect caused by capillary action between fabric fibers, and reduce the mechanical loss of the product caused by humid and hot conditions. Attached Figure Description

[0047] Figure 1 The image shows an electron microscope image of the fabric surface after the PVC in the No. 6 membrane structure material of Example 1 has been dissolved in a solvent (THF). It can be clearly seen from the image that the surface is relatively smooth, which indicates that there is no cross-linking between the PVC resin and the fabric at this time.

[0048] Figure 2 The image shows an electron microscope (EMS) image of the fabric surface of the No. 6 membrane structure material in Example 1 after hygrothermal aging and PVC dissolution by a solvent (THF). The image shows that an organic film appeared on the surface, indicating that there is a cross-linking effect between the PVC resin and the fabric after hygrothermal aging; a large amount of organic film is visible. Detailed Implementation

[0049] In the following examples and comparative examples, the base fabric used is 2000D*2600D polyester plain weave woven fabric with a weight of 366 g / m².

[0050] The PVC paste resin used is CPM-31.

[0051] Example 1: Selection of the ratio of primary crosslinking agent to co-crosslinking agent in composite crosslinking agent

[0052] 1. Specific steps of the hydrophobic treatment process for the base fabric:

[0053] The base fabric is unwound and immersed in the tank for impregnation. The impregnation solution in the tank consists of deionized water and a hydrophobic agent in a volume ratio of 100:25. The hydrophobic agent is TG5673. After impregnation for 20 seconds, the fabric is taken out and placed in an oven for setting. The setting temperature is 170℃ and the setting time is 2 minutes.

[0054] 2. Specific steps for preparing PVC slurry:

[0055] The formula for PVC paste is as follows: 100g PVC paste resin, 60g plasticizer DINP, 3g barium zinc stabilizer, and 1.5g composite crosslinking agent. Stir and set aside.

[0056] Among them, the mass ratios of (3-mercaptopropyl)trimethoxysilane and dicumyl peroxide in the composite crosslinking agent were 1:0, 1:0.1, 1:0.3, 1:0.5, 1:0.8, 1:1, and 0:1, respectively, to prepare seven different PVC slurries, which were designated as slurries 1#, 2#, 3#, 4#, 5#, 6#, and 7#.

[0057] 3. Specific steps for the composite processing of base fabric and PVC slurry:

[0058] The PVC slurry prepared in step 2 is applied to the front side of the base fabric treated in step 1 by roller coating, with a coating amount of 100 g / m. 2 Then, the PVC slurry from step 2 is coated onto the other side of the base fabric using a roller coating method, with a coating amount of 100g / m². 2After pre-drying at 140℃ for 3 minutes, plasticizing at 180℃ for 5 minutes, and cooling, 7 corresponding PVC building membrane structure materials were obtained, which were labeled as membrane structure materials 1#, 2#, 3#, 4#, 5#, 6#, and 7# respectively.

[0059] Two samples of No. 6 membrane structure material were taken. One sample was subjected to a damp heat aging test (the sample was dried to constant weight and then added to distilled water at 70°C for a one-week accelerated damp heat aging test). After the test, the PVC matrix in both samples of No. 6 membrane structure material was dissolved in THF solvent and then placed under an electron microscope to observe the surface morphology of the fabric. Figure 1 This is a SEM image of the surface of a PET fabric that has not undergone damp heat aging. Figure 2 This is a SEM image of the fabric surface after humid heat aging.

[0060] from Figure 1 It is clearly visible that its surface is relatively smooth, indicating that there is no cross-linking between the PVC resin and the PET fabric at this point; from Figure 2 An organic film can be seen on its surface. This may be because, after being subjected to wet heat aging, the composite crosslinking agent reacted with the PVC resin and the hydrophobic agent on the fabric, respectively. This made it impossible for THF to dissolve and wash away the crosslinking substances. As a result, a large number of organic films can be clearly observed on the surface of the fabric under an electron microscope.

[0061] Example 2:

[0062] 1. Specific steps of the hydrophobic treatment process for the base fabric:

[0063] The base fabric is unwound and immersed in the tank for impregnation. The impregnation solution in the tank consists of deionized water and a hydrophobic agent in a volume ratio of 100:25. The hydrophobic agent is TG5673. After impregnation for 20 seconds, the fabric is taken out and placed in an oven for setting. The setting temperature is 170℃ and the setting time is 2 minutes.

[0064] 2. Specific steps for preparing PVC slurry:

[0065] The formula for PVC slurry is as follows: 100g PVC paste resin, 60g plasticizer DINP, 3g barium zinc stabilizer, and 1g composite crosslinking agent. Stir to obtain PVC slurry for later use, and label it as No. 8.

[0066] In the composite crosslinking agent, the mass ratio of (3-mercaptopropyl)trimethoxysilane to dicumyl peroxide is 1:1.

[0067] 3. Specific steps for the composite processing of base fabric and PVC slurry:

[0068] The PVC slurry prepared in step 2 is applied to the front side of the base fabric treated in step 1 by roller coating, with a coating amount of 100 g / m. 2Then, the PVC slurry from step 2 is coated onto the other side of the base fabric using a roller coating method, with a coating amount of 100g / m². 2 After pre-baking at 140℃ for 3 minutes, plasticizing at 180℃ for 5 minutes, and cooling, 5 corresponding PVC building membrane structure materials were obtained, which were respectively designated as No. 8 building membrane structure material.

[0069] Comparative Example 1: No hydrophobic treatment performed

[0070] 1. Specific steps of the hydrophobic treatment process for the base fabric:

[0071] The base fabric is unwound and immersed in a tank for immersion and rolling. The immersion solution in the tank is deionized water. After immersion for 20 seconds, it is taken out and placed in an oven for setting. The setting temperature is 170℃ and the setting time is 2 minutes.

[0072] 2. Specific steps for preparing PVC slurry:

[0073] The formula for PVC paste is as follows (parts by weight): 100g PVC paste resin, 60g plasticizer DINP, 3g barium zinc stabilizer, 1.5g composite crosslinking agent, stir and set aside.

[0074] In the composite crosslinking agent, the mass ratio of (3-mercaptopropyl)trimethoxysilane to dicumyl peroxide is 1:1, and PVC slurry is prepared, which is denoted as No. 9 slurry.

[0075] 3. Specific steps for the composite processing of base fabric and PVC slurry:

[0076] The PVC slurry prepared in step 2 is applied to the front side of the base fabric treated in step 1 by roller coating, with a coating amount of 100 g / m. 2 Then, the PVC slurry from step 2 is coated onto the other side of the base fabric using a roller coating method, with a coating amount of 100g / m². 2 After pre-baking at 140℃ for 3 minutes, plasticizing at 180℃ for 5 minutes, and cooling, PVC building membrane structure material is obtained, which is marked as No. 9 membrane structure material.

[0077] Comparative Example 2: No composite crosslinking agent added

[0078] 1. Specific steps of the hydrophobic treatment process for the base fabric:

[0079] The base fabric is unwound and immersed in the tank for impregnation. The impregnation solution in the tank consists of deionized water and a hydrophobic agent in a volume ratio of 100:25. The hydrophobic agent is TG5673. After impregnation for 20 seconds, the fabric is taken out and placed in an oven for setting. The setting temperature is 170℃ and the setting time is 2 minutes.

[0080] 2. Specific steps for preparing PVC slurry:

[0081] The formula for PVC slurry is as follows (parts by weight): 100g PVC paste resin, 60g plasticizer DINP, 3g barium zinc stabilizer, 0g composite crosslinking agent. Stir to obtain 10# PVC slurry for later use.

[0082] 3. Specific steps for the composite processing of base fabric and PVC slurry:

[0083] The PVC slurry prepared in step 2 is applied to the front side of the base fabric treated in step 1 by roller coating, with a coating amount of 100 g / m. 2 Then, the PVC slurry from step 2 is coated onto the other side of the base fabric using a roller coating method, with a coating amount of 100g / m². 2 After pre-baking at 140℃ for 3 minutes, plasticizing at 180℃ for 5 minutes, and cooling, 10# PVC building membrane structure material is obtained.

[0084] Performance testing:

[0085] The mechanical properties (tensile strength and peel strength) of the eight membrane structure materials prepared in Examples 1 and 2 and the 9# and 10# membrane structure materials prepared in Comparative Examples 1 and 2 before and after wet heat aging treatment were tested respectively, and the mechanical property loss rate of each membrane structure material after wet heat aging treatment was calculated. The results are shown in Table 1.

[0086] The specific operation of the damp heat aging treatment is as follows:

[0087] The sample was dried to constant weight and then added to distilled water at 70°C for accelerated wet heat aging. The sample was removed after one week and subsequent performance tests were conducted.

[0088] Tensile strength test method: GB / T 3923.1-2013 "Textiles - Tensile properties of fabrics - Part 1: Determination of breaking strength and elongation at break (strip method)".

[0089] Peel strength test method: FZ / T 60039-2013 "Test method for peel strength of coated fabrics for membrane structures".

[0090] Table 1. Performance test results of the membrane structure materials prepared in Examples 1-2 and Comparative Examples 1-2.

[0091]

[0092]

[0093] As can be seen from Table 1, compared with Comparative Example 1, the mechanical properties (tensile strength, peel strength) of the seven membrane structure materials in Example 1 are better than those in Comparative Example 1, which shows the importance of hydrophobic treatment in the preparation process of membrane structure materials.

[0094] Compared to Comparative Example 2, the tensile properties and peel strength of membrane structure materials #3 to #6 in Example 1 are superior to those in Comparative Example 2. While the tensile strength of membrane structure materials #1, #2, and #7 is slightly better than that in Comparative Example 2, their peel strength is inferior. This may be because the co-crosslinking agent can generate active free radicals in a humid and hot environment, which in turn stimulates the hydrophobic agent to generate active free radicals that react with the active free radicals generated after the hydrolysis of the main crosslinking agent, forming a stable crosslinked network between PVC and the fabric. This reduces the mechanical loss of the PVC membrane structure material in a humid and hot environment. The content of the co-crosslinking agent in the composite crosslinking agent used in membrane structure materials #3 to #6 gradually increases, which promotes better crosslinking reactions between the hydrophobic agent and the main crosslinking agent in a humid and hot environment, thus effectively improving the resistance of the membrane structure material to humid and hot aging. However, the crosslinking agents added to membrane structure materials #1 and #7 are single crosslinking agents (main crosslinking agent or co-crosslinking agent), which cannot undergo crosslinking reaction with hydrophobic agents under humid and hot conditions to form a network structure. The connection between PVC and fabric is poor, and the crosslinking agent itself has a certain water absorption, resulting in a serious decline in mechanical properties (especially peel performance). Although composite crosslinking agents (main crosslinking agent and co-crosslinking agent) are added to membrane structure material #2, the amount of co-crosslinking agent added is small, which still cannot enable the main crosslinking agent to undergo a good crosslinking reaction with the hydrophobic agent.

[0095] Among them, the peel strength of membrane structure materials #5 and #6 not only did not decrease but actually increased, and the loss of tensile strength was also negligible. This indicates that selecting an appropriate ratio of primary crosslinking agent and secondary crosslinking agent can enable PVC membrane structure materials to have excellent resistance to humid heat aging.

[0096] Compared to membrane structure materials using only the primary crosslinking agent (1#) or primary crosslinking agent (7#), the loss of mechanical properties (tensile strength, peel strength) in membrane structure materials using composite crosslinking agents decreases with increasing co-crosslinking agent content in the composite crosslinking agent. This may be because the co-crosslinking agent releases a large amount of active substances in a humid and hot environment, causing the hydrophobic agent and the primary crosslinking agent in PVC to undergo a crosslinking reaction at their interface, forming an organic network interlocking structure and preventing the delamination of fibers and PVC resin. When the ratio of primary crosslinking agent to co-crosslinking agent in the composite crosslinking agent is greater than 1:0.8, the changes in the mechanical properties of the membrane structure material basically tend to be balanced. This may be because the active groups in the hydrophobic agent are limited, and when the crosslinking reaction reaches saturation, the reaction tends to peak; that is, the tensile strength loss rate of the membrane structure material is less than or equal to 0.1%, which is almost negligible; while the peel strength of the membrane structure material not only does not suffer a loss but also increases by more than 5%.

[0097] Compared with the 6# membrane structure material prepared in Example 1, the tensile properties and peel strength of the 8# membrane structure material prepared in Example 2 are slightly inferior. This is because the amount of composite crosslinking agent added to the 8# membrane structure material is less, which results in it not being able to form a crosslinking network structure with the hydrophobic agent as well, thus affecting the mechanical properties of the membrane structure material.

Claims

1. A method for preparing a PVC building membrane structure material resistant to damp heat aging, characterized in that, Includes the following steps: (1) Use a hydrophobic agent to treat the fabric with hydrophobicity; (2) PVC paste is prepared using PVC paste resin, plasticizer, heat stabilizer and composite crosslinking agent as raw materials; (3) The PVC slurry is coated on both sides of the fabric that has been treated with hydrophobicity, and then plasticized to obtain the moisture-resistant and heat-aging-resistant PVC building membrane structure material. The hydrophobic agent is a fluorinated acrylate block copolymer; The composite crosslinking agent includes a primary crosslinking agent and a secondary crosslinking agent; wherein the primary crosslinking agent is a mercaptosilane coupling agent and the secondary crosslinking agent is a peroxide.

2. The method for preparing the PVC building membrane structure material resistant to damp heat aging according to claim 1, characterized in that, The PVC slurry is prepared from the following components in parts by weight: 80-100 parts of PVC paste resin 55-80 parts of plasticizer 2-4 parts heat stabilizer 0.01 to 3 parts of composite crosslinking agent.

3. The method for preparing the hygrothermal aging resistant PVC building membrane structure material according to claim 1, characterized in that, In the composite crosslinking agent, the mass ratio of the main crosslinking agent to the co-crosslinking agent is 1:(0.01~2).

4. The method for preparing the hygrothermal aging resistant PVC building membrane structure material according to claim 1, characterized in that, The plasticizer is one or both of diisononyl phthalate and n-butyl phthalate; The heat stabilizer is a barium-zinc composite stabilizer.

5. The method for preparing the PVC building membrane structure material resistant to damp heat aging according to claim 1, characterized in that, In step (3), when coating both sides of the fabric, the coating amount is 50~150 g / m². 2 .

6. The method for preparing the hygrothermal aging resistant PVC building membrane structure material according to claim 1, characterized in that, In step (1), the specific operation of hydrophobic treatment of the fabric is as follows: After mixing the hydrophobic agent with deionized water, the fabric is unrolled and immersed in the mixture. After impregnation and rolling, remove the product, dry and set its shape; The volume ratio of hydrophobic agent to deionized water is (10~40):100, the padding time is 10~120s, the setting temperature is 130~180℃, and the setting time is 1~10min.

7. The method for preparing the hygrothermal aging resistant PVC building membrane structure material according to claim 1, characterized in that, In step (3), plasticizing includes pre-baking and plasticizing. The pre-baking temperature is 120℃~150℃ and the pre-baking time is 2~10min; the plasticizing temperature is 160~200℃ and the plasticizing time is 3~8min.

8. A PVC building membrane structure material resistant to damp heat aging, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

Images