Modified PVC sheet reaching UL94-5VA flame retardant level and preparation method and application thereof

Abstract

The invention relates to the technical field of composite materials, and provides a PVC sheet reaching the UL94-5VA flame retardant level and a preparation method and application thereof. The thickness of the PVC sheet is smaller than or equal to 8 mm, and raw materials for preparing the modified PVC sheet are mainly composed of PVC and a flame retardant. The flame retardant accounts for more than 10% of the total mass of the flame retardant and PVC, and the flame retardant comprises one or a combination of more than two of a flame retardant X, a flame retardant Y and a ceramic forming agent; pVC is modified through a specific flame retardant, the flame retardant property of the modified PVC can reach the UL94-5VA flame retardant level, and the granules can be directly molded to obtain sheets through a plastic uptake processing technology, are used in the fields of refrigerator inclined plates and the like, and are high in production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a modified PVC sheet reaching the UL94-5VA flame retardant grade, a preparation method and applications thereof. Background Art

[0002] Different fields have different requirements for the flame retardant grade of polymer plastics. In the fields of electronic appliances, wires and cables, and automobiles, polymer plastics are usually required to have a flame retardant grade that reaches the highest UL94-5VA, rather than just passing the UL94 V0 level. Moreover, the UL94-5VA test is conducted by directly burning along the thickness direction of the sample, so the thinner the plastic, the more difficult it is to pass the UL94-5VA test. The national standard GB4076 requires that the flame retardant grade of the material in contact with the foaming material, that is, the compressor compartment, should also reach the UL94-5VA flame retardant grade. However, the current refrigerator ramp is made of metal and PP hollow board, such as Figure 6 As shown, the flame retardancy rating of PP hollow board cannot reach 5VA, which does not meet the national standard. PVC has excellent insulation, mechanical properties, and processing properties, and is widely used in artificial leather, electronic appliances, wire and cable, building materials, and textiles. Due to the high melting point and poor melt fluidity of PVC resin, it is difficult to process and form, and usually requires the addition of plasticizers. PVC plastic containing large amounts of plasticizers significantly reduces its flame retardancy, making it difficult to achieve the UL94-5VA flame retardancy rating. Summary of the Invention

[0003] The present invention provides a modified PVC sheet that achieves UL94-5VA flame retardancy, as well as its preparation method and application. This allows thinner refrigerator parts to be produced through vacuum molding, ensuring the flame retardancy reaches UL94-5VA. This improves component molding efficiency while ensuring that the components meet national flame retardancy standards.

[0004] In a first aspect, the present invention provides a modified PVC sheet having a flame retardant rating of UL94-5VA, wherein the thickness of the modified PVC sheet is less than or equal to 8 mm; the raw materials for preparing the modified PVC sheet are mainly composed of PVC and a flame retardant;

[0005] The flame retardant includes one or a combination of two or more of flame retardant X, flame retardant Y, and porcelain-forming agent;

[0006] The flame retardant X includes one or a combination of two or more of ammonium polyphosphate, decabromodiphenylethane, aluminum hypophosphite, diethyl aluminum hypophosphite, and a carbonizing agent;

[0007] The flame retardant Y comprises one or a combination of two or more of antimony trioxide, magnesium hydroxide, aluminum hydroxide or metal phosphate compounds;

[0008] The porcelain-forming agent comprises one or a combination of two or more of low-melting-point glass powder, chopped glass fiber, mica flakes, kaolin and zinc borate.

[0009] According to the modified PVC sheet that reaches UL94-5VA flame retardancy provided by the present invention, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the flame retardant X accounts for less than 20% of the sum of the mass of the flame retardant and the PVC;

[0010] Alternatively, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the flame retardant Y accounts for less than 30% of the sum of the mass of the flame retardant and the PVC;

[0011] Alternatively, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the porcelain-forming agent accounts for less than 20% of the total mass of the flame retardant and the PVC.

[0012] According to the modified PVC sheet that reaches the UL94-5VA flame retardant grade provided by the present invention, when the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, the flame retardant accounts for more than 30% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide in a mass ratio of 6.5-7.5:1.5-2.5:0.5-1.5.

[0013] According to the modified PVC sheet that reaches the UL94-5VA flame retardant grade provided by the present invention, when the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, the flame retardant further includes a flame retardant X mainly composed of aluminum hypophosphite and decabromodiphenylethane; preferably, the mass ratio of the flame retardant Y to the flame retardant X is 3.5-4.5:0.5-1.5.

[0014] According to the modified PVC sheet that reaches the UL94-5VA flame retardant grade provided by the present invention, when the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate in a mass ratio of 1.5-2.5:6.5-7.5:0.5-1.5.

[0015] According to the modified PVC sheet material that reaches the UL94-5VA flame retardant grade provided by the present invention, when the flame retardant is mainly composed of chopped glass fibers, low-melting point glass powder and mica flakes, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of chopped glass fibers, low-melting point glass powder and mica flakes in a mass ratio of 4-4.5:4.5-3.5:0.5-1.

[0016] According to the modified PVC sheet material reaching the UL94-5VA flame retardant grade provided by the present invention, the flame retardant comprises 2 to 10 parts of flame retardant X, 0 to 14 parts of flame retardant Y and 0 to 10 parts of porcelain-forming agent, and the flame retardant Y and the porcelain-forming agent are not both 0;

[0017] Preferably, the flame retardant X is mainly composed of ammonium polyphosphate and a char-forming agent, or the flame retardant X is mainly composed of aluminum hypophosphite and decabromodiphenylethane; further preferably, the flame retardant X is mainly composed of aluminum hypophosphite and decabromodiphenylethane in a mass ratio of 7 to 9:3 to 1, or the flame retardant X is mainly composed of ammonium polyphosphate and a char-forming agent in a mass ratio of 8 to 9:2 to 1;

[0018] The porcelain-forming agent is mainly composed of chopped glass fibers and low-melting-point glass powder, or the porcelain-forming agent is mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes; further preferably, the porcelain-forming agent is mainly composed of chopped glass fibers and low-melting-point glass powder in a mass ratio of 7-9:3-1, or the porcelain-forming agent is mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes in a mass ratio of 4-4.5:4.5-3.5:0.5-1;

[0019] The flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, or the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate; further preferably, the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide in a mass ratio of 6.5-7.5:1.5-2.5:0.5-1.5, or the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate in a mass ratio of 1.5-2.5:6.5-7.5:0.5-1.5.

[0020] According to the modified PVC sheet material reaching the UL94-5VA flame retardant grade provided by the present invention, the flame retardant is mainly composed of the following components:

[0021] A flame retardant X mainly composed of ammonium polyphosphate and a carbon former, a flame retardant Y mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, and a porcelain former mainly composed of chopped glass fibers and low-melting-point glass powder; the mass ratio of the flame retardant X, the flame retardant Y and the porcelain former is 7.5-8.5:11.5-12.5:4.5-5.5; preferably, the flame retardant accounts for more than 25% of the total mass of the flame retardant and the PVC;

[0022] Alternatively, the flame retardant is mainly composed of the following components:

[0023] A flame retardant X mainly composed of ammonium polyphosphate and a carbon former, a flame retardant Y mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, and a ceramic former mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes; the mass ratio of the flame retardant X, the flame retardant Y and the ceramic former is 3.5-4.5:7.5-8.5:2.5-3.5; preferably, the flame retardant accounts for more than 20% of the total mass of the flame retardant and the PVC;

[0024] In a second aspect, the present invention further provides a method for preparing the modified PVC sheet having a flame retardant grade of UL94-5VA as described above.

[0025] In a third aspect, the present invention further provides an application of the modified PVC sheet having the UL94-5VA flame retardant grade as described above in the fields of microelectronics, electronic appliances, wires and cables, and automobiles.

[0026] The present invention provides a modified PVC sheet that reaches the UL94-5VA flame retardancy level, as well as a preparation method and application thereof. PVC is modified by a specific flame retardant so that its flame retardancy reaches the UL94-5VA flame retardancy level after modification. The pellets can be directly formed into sheets through a vacuum forming process, and are used in fields such as refrigerator ramps, with high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a sample photo of the modified PVC sheet obtained in Examples 1, 3 to 6 provided by the present invention after being subjected to UL94-5VA flame retardancy test;

[0029] Figure 2 This is a sample photo of the modified PVC sheet obtained in Examples 7, 9 and 10 provided by the present invention after being subjected to UL94-5VA flame retardancy test;

[0030] Figure 3 This is a sample photo of the modified PVC sheet obtained in Examples 12 to 15 provided by the present invention after being subjected to UL94-5VA flame retardancy test;

[0031] Figure 4 This is a sample photo of the modified PVC sheet obtained in Examples 18 to 21 provided by the present invention after being subjected to UL94-5VA flame retardancy test;

[0032] Figure 5This is a sample photo of the modified PVC sheet obtained in Examples 23 to 26 provided by the present invention after being subjected to UL94-5VA flame retardancy test;

[0033] Figure 6 This is a photo of a refrigerator inclined plate made of galvanized steel plate and PP hollow plate in the prior art;

[0034] Figure 7 This is a photograph of the modified PVC sheet obtained in Example 25 of the present invention being applied to a refrigerator inclined plate after being vacuum-formed;

[0035] Reference numerals: 1- galvanized steel plate, 2- PP hollow plate. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0037] The following combination Figure 1-Figure 7 The invention describes a modified PVC sheet material having a flame retardant grade of UL94-5VA, a preparation method thereof and an application thereof.

[0038] Specifically, an embodiment of the present invention provides a modified PVC sheet that reaches the UL94-5VA flame retardant level, wherein the thickness of the modified PVC sheet is less than or equal to 8 mm; the raw materials for preparing the modified PVC sheet are mainly composed of PVC and a flame retardant;

[0039] The flame retardant includes one or a combination of two or more of flame retardant X, flame retardant Y, and a ceramic-forming agent; when the flame retardant is a combination of two substances, it can generally be called a compound flame retardant;

[0040] The flame retardant X comprises one or a combination of two or more of ammonium polyphosphate, decabromodiphenylethane, aluminum hypophosphite, diethyl aluminum hypophosphite, and a carbon-forming agent; preferably, the flame retardant X comprises one or two of ammonium polyphosphate and a carbon-forming agent; more preferably, a mixture of the two;

[0041] The flame retardant Y includes one or a combination of two or more of antimony trioxide, magnesium hydroxide, aluminum hydroxide or metal phosphate compounds; preferably, the flame retardant Y includes one or a combination of two or more of antimony trioxide, magnesium hydroxide, aluminum hydroxide and zirconium phosphate; further preferably, the flame retardant Y includes magnesium hydroxide and aluminum hydroxide;

[0042] The porcelain-forming agent includes one or a combination of two or more of low-melting-point glass powder, chopped glass fibers, mica flakes, kaolin and zinc borate; the melting point of the low-melting-point glass powder is 300-600°C; preferably, the porcelain-forming agent includes one or a combination of two or more of low-melting-point glass powder, chopped glass fibers and mica flakes; further preferably, the porcelain-forming agent includes one or two of chopped glass fibers and low-melting-point glass powder.

[0043] The lower the content of the flame retardant in the present invention, the lower the preparation cost of the obtained modified PVC sheet, and the processing performance of the modified PVC sheet is easier to control.

[0044] In some embodiments, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the flame retardant X accounts for less than 20% of the sum of the mass of the flame retardant and the PVC;

[0045] In some embodiments, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the flame retardant Y accounts for less than 30% of the sum of the mass of the flame retardant and the PVC;

[0046] In some embodiments, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the porcelain-forming agent accounts for less than 20% of the total mass of the flame retardant and the PVC.

[0047] In some embodiments, when the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, the flame retardant accounts for more than 30% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide in a mass ratio of 6.5-7.5:1.5-2.5:0.5-1.5.

[0048] In some embodiments, when the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, the flame retardant further includes a flame retardant X mainly composed of aluminum hypophosphite and decabromodiphenylethane; preferably, the mass ratio of the flame retardant Y to the flame retardant X is 3.5-4.5:0.5-1.5.

[0049] In some embodiments, when the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate in a mass ratio of 1.5-2.5:6.5-7.5:0.5-1.5.

[0050] In some embodiments, when the flame retardant is mainly composed of chopped glass fibers, low-melting point glass powder and mica flakes, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of chopped glass fibers, low-melting point glass powder and mica flakes in a mass ratio of 4 to 4.5:4.5 to 3.5:0.5 to 1.

[0051] In some embodiments, the flame retardant comprises 2 to 10 parts of flame retardant X, 0 to 14 parts of flame retardant Y, and 0 to 10 parts of a ceramic forming agent, and the flame retardant Y and the ceramic forming agent are not both 0;

[0052] Preferably, the flame retardant X is mainly composed of ammonium polyphosphate and a char-forming agent, or the flame retardant X is mainly composed of aluminum hypophosphite and decabromodiphenylethane; further preferably, the flame retardant X is mainly composed of aluminum hypophosphite and decabromodiphenylethane in a mass ratio of 7 to 9:3 to 1, or the flame retardant X is mainly composed of ammonium polyphosphate and a char-forming agent in a mass ratio of 8 to 9:2 to 1;

[0053] The porcelain-forming agent is mainly composed of chopped glass fibers and low-melting-point glass powder, or the porcelain-forming agent is mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes; further preferably, the porcelain-forming agent is mainly composed of chopped glass fibers and low-melting-point glass powder in a mass ratio of 7-9:3-1, or the porcelain-forming agent is mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes in a mass ratio of 4-4.5:4.5-3.5:0.5-1;

[0054] The flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, or the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate; further preferably, the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide in a mass ratio of 6.5-7.5:1.5-2.5:0.5-1.5, or the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate in a mass ratio of 1.5-2.5:6.5-7.5:0.5-1.5.

[0055] In some embodiments, the flame retardant is mainly composed of the following components:

[0056] A flame retardant X mainly composed of ammonium polyphosphate and a carbon former, a flame retardant Y mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, and a porcelain former mainly composed of chopped glass fibers and low-melting-point glass powder; the mass ratio of the flame retardant X, the flame retardant Y and the porcelain former is 7.5-8.5:11.5-12.5:4.5-5.5; preferably, the flame retardant accounts for more than 25% of the total mass of the flame retardant and the PVC;

[0057] In some embodiments, the flame retardant is mainly composed of the following components:

[0058] A flame retardant X mainly composed of ammonium polyphosphate and a carbon former, a flame retardant Y mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, and a ceramic former mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes; the mass ratio of the flame retardant X, the flame retardant Y and the ceramic former is 3.5-4.5:7.5-8.5:2.5-3.5; preferably, the flame retardant accounts for more than 20% of the total mass of the flame retardant and the PVC;

[0059] In some embodiments, the present invention further provides a method for preparing the modified PVC sheet having a flame retardant rating of UL94-5VA as described above.

[0060] Preferably, the preparation method comprises:

[0061] (1) Prepare the raw materials in proportion and mix them for the first time at a mixing speed of 1000-1500 rpm;

[0062] (2) The modified PVC pellets are obtained by melting, mixing, extruding, cooling, drying and pelletizing through a twin-screw extruder, wherein the temperature of each zone of the twin-screw extruder barrel is maintained between 200 and 250°C.

[0063] (3) Taking a certain amount of extruded PVC pellets, using a flat-plate vulcanizer to press into a PVC sheet of a certain thickness, wherein the upper and lower plates of the flat-plate vulcanizer are set at a temperature of 95°C, the pressing time is 1 to 10 minutes, and the speed of the twin-screw extruder is 100 to 200 rpm.

[0064] In some embodiments, the present invention also provides a modified PVC sheet material having a flame retardant grade of UL94-5VA as described above for use in the fields of microelectronics, electronic appliances, wires and cables, and automobiles. Figure 7 The inclined plate is directly formed from the modified PVC sheet through a vacuum forming process.

[0065] The following describes the method for preparing the modified PVC sheet material having a flame retardant grade of UL94-5VA according to the present invention with reference to specific implementation cases.

[0066] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0067] Among them, the low-melting-point glass powder has a melting point of 300-600°C and a mesh size of 2000 mesh or more;

[0068] The monofilament diameter of short glass fiber is 9 to 13 μm and the length is 6 to 30 mm;

[0069] The diameter-to-thickness ratio of the mica sheet is greater than 80, and the mesh size is 100 mesh or above;

[0070] The PVC powder used in the examples of this invention was provided by Hefei Chenle Plastic Co., Ltd., under the brand name CL510. CL510 is made from Yinglite SG-5 PVC by adding plasticizers, stabilizers, impact modifiers, and other additives. Compared to Yinglite SG-5, CL510 has an improved tensile strength of approximately 15 MPa, while maintaining similar flame retardancy.

[0071] Examples 1 to 6

[0072] A method for preparing a modified PVC sheet, comprising the following steps:

[0073] (1) Prepare the materials according to Table 1 below.

[0074] (2) Add PVC powder and other additives into a high-speed mixer according to the proportions in Table 1 below, mix them evenly at a speed of 1200 rpm, and then melt, mix, extrude, cool, dry and pelletize them through a twin-screw extruder to obtain modified PVC pellets.

[0075] (3) Using the modified PVC pellets obtained in step (2) as raw materials, the modified PVC sheets were pressed and formed on a flat-plate vulcanizing press to obtain modified PVC sheets having a thickness of approximately 8 mm, a length of 125 mm, and a width of 130 mm. During the pressing process, the upper and lower plates were set at a temperature of 95° C., and the pressing time was 1 minute.

[0076] The obtained modified PVC sheet was tested to see if it passed the UL94-5VA flame retardancy rating. The test results are shown in Table 1.

[0077] Table 1

[0078]

[0079]

[0080] As can be seen from Table 1, the mass proportion of PVC powder in Examples 1 to 5 is 80%, and the total mass proportion of the flame retardant additives is 20%. The mass proportion of PVC powder in Example 6 is 70%, and the total mass proportion of the flame retardant additives is 30%. The test results show that adding only 20% of the auxiliary flame retardant C (Example 2) is not enough to make the sheet reach the UL94-5VA flame retardant level. It can only pass when the proportion of the auxiliary flame retardant C is increased to 30% (Example 6). Adding only 20% of the auxiliary flame retardant D (Example 3) can make the sheet reach the UL94-5VA flame retardant level. Therefore, the auxiliary flame retardant C is better than the auxiliary flame retardant D in the composite system of the present invention.

[0081] Collect photos of samples after UL94-5VA flame retardancy test of Examples 1, 3 to 6, as shown in the figure. Figure 1 As shown, from Figure 1 It can be seen that Examples 1 and 3 to 6 all form extremely dense carbon layers.

[0082] Examples 7 to 11

[0083] A method for preparing a modified PVC sheet, the steps of which are substantially the same as those of Example 1, except that the formulations of Examples 7 to 11 are different, as shown in Table 2, and the test results are shown in Table 2.

[0084] Table 2

[0085]

[0086]

[0087] As can be seen from Table 2, the mass proportion of PVC powder in Examples 7 to 11 is 90%, and the total mass proportion of flame retardant additives is 10%. The test results show that although the content of the compounded flame retardant in Examples 7, 9, and 10 is only half (only 10 wt%) compared to Examples 1, 3, and 4, the modified PVC sheets obtained can all achieve the UL94-5VA flame retardancy rating.

[0088] Collect samples of Examples 7, 9 and 10 after UL94-5VA flame retardancy test, as shown in the following figure: Figure 2 As shown. Figure 2 It can be seen that Examples 7, 9, and 10 all formed extremely dense char layers, and achieved results substantially equivalent to those of Examples 1 and 3 to 6. This indicates that the addition of only 10 parts of the corresponding compounded flame retardants can achieve a UL94-5VA flame retardancy rating for a modified PVC sheet with a thickness of 8 mm.

[0089] Examples 12 to 15

[0090] A method for preparing a modified PVC sheet, the steps of which are substantially the same as those of Example 1, except that the formulations of Examples 12 to 15 are different, as shown in Table 3. The dimensions of the resulting modified PVC sheet are approximately 6 mm thick, 125 mm long, and 130 mm wide. The test results of the corresponding sheets are shown in Table 3.

[0091] Table 3

[0092]

[0093]

[0094] As can be seen from Table 3, the mass proportion of PVC powder in Examples 12 to 15 is 90%, and the total mass proportion of the flame retardant additives is 10%. The test results show that compared with Example 7, although the content of the compound flame retardant in Examples 12 to 15 is still 10wt%, the content of the more expensive main flame retardant A is reduced, and the thickness of the obtained PVC sheet is reduced from 8mm to 6mm. The content of the main flame retardant A in Examples 12 to 15 is controlled at 4wt%, the content of the porcelain-forming agent B or the porcelain-forming agent E is 2wt%, and the content of the auxiliary flame retardant C or the auxiliary flame retardant D is 4wt%. The study found that the modified PVC sheets can still reach the UL94-5VA flame retardant level. This shows that only 4wt% of the main flame retardant A, combined with 2wt% of the above-mentioned porcelain-forming agent and 4wt% of the above-mentioned auxiliary flame retardant, can achieve a good flame retardant effect.

[0095] Collect samples of Examples 12 to 15 after UL94-5VA flame retardancy test, as shown in the following figure: Figure 3 As shown. Figure 3 It can be seen that Examples 12 to 15 all formed extremely dense carbon layers.

[0096] Examples 16-17

[0097] A method for preparing a modified PVC sheet, the steps of which are basically the same as those of Example 12, except that the formulas of Examples 16 to 17 are different, as shown in Table 4, and the test results of the corresponding sheets are shown in Table 4.

[0098] Table 4

[0099]

[0100]

[0101] As can be seen from Table 4, in Examples 16-17, the weight percentage of PVC powder is 90%, and the total weight percentage of flame-retardant additives is 10%. Test results show that compared to Examples 12 and 14, Examples 16 and 17 further reduce the content of the more expensive main flame retardant A (from 4 wt% to 2 wt%), and the resulting modified PVC sheets still achieve a UL95-5VA flame retardancy rating.

[0102] Examples 18 to 22

[0103] A method for preparing a modified PVC sheet, the steps of which are substantially the same as those of Example 12, except that the formulations of Examples 18 to 22 are different, as specifically shown in Table 5, and the dimensions of the resulting modified PVC sheet are approximately 5 mm thick, 125 mm long, and 130 mm wide. The test results of the corresponding sheets are shown in Table 5.

[0104] Table 5

[0105]

[0106]

[0107] As can be seen from Table 5, compared to Examples 12 to 15, the thickness of the modified PVC obtained in Examples 18 to 22 was reduced from 6 mm to 5 mm. Maintaining the main flame retardant A content at 4 wt%, the compounded flame retardant content in Examples 18 and 19 was increased from 10 wt% to 15 wt%, and in Examples 20 and 21 from 10 wt% to 20 wt%. Even with a reduced sheet thickness, when the flame retardant content was slightly increased, the resulting modified PVC sheet still achieved a UL94-5VA flame retardancy rating. Furthermore, from a cost perspective, the formulation used in Example 22 was the most economical.

[0108] Collect samples of Examples 18 to 21 after UL94-5VA flame retardancy test, as shown in the following figure: Figure 4 As shown. Figure 4 It can be seen that when the thickness of the modified PVC is reduced from 6 mm to 5 mm, samples No. 18 to 22 of Examples prepared by compounding the flame retardant can all pass the UL94-5VA test, achieving the result that the flame does not burn through.

[0109] Examples 23 to 26

[0110] A method for preparing a modified PVC sheet, the steps of which are basically the same as those of Examples 18 to 22, except that the formulations of Examples 23 to 26 are different, as shown in Table 6, and the thickness of the resulting modified PVC sheets is different (see Table 6 for details). The test results of the corresponding sheets are shown in Table 6.

[0111] Table 6

[0112]

[0113]

[0114] As can be seen from Table 6, compared to Examples 18 to 22, the thickness of the modified PVC sheets obtained in Examples 23 to 26 was reduced by approximately 2 mm from 5 mm. The reduction in thickness greatly increases the difficulty of flame retardancy. PVC sheets with a thickness of about 2 mm on the market are difficult to achieve the UL94-5VA flame retardancy level. Examples 23 and 24 have the same formulations as Examples 20 and 21, respectively. Examples 25 and 26 increase the content of the compounded flame retardant from 20 wt% to 25 wt%, respectively, based on Examples 23 and 24. The study found that Examples 23, 24, and 26 all failed to pass the UL94-5VA flame retardancy test, while the modified PVC sheet in Example 25 successfully passed the UL94-5VA test. It shows that the compound flame retardant provided by the present invention can achieve the UL94-5VA flame retardancy level for a PVC sheet of about 2 mm with an addition amount of only 25 wt% (8 wt% of main flame retardant A, 5 wt% of ceramic agent B and 12 wt% of auxiliary flame retardant C), which exceeds the effect brought by most compound flame retardants for PVC on the market.

[0115] Collect photos of samples after UL94-5VA flame retardancy test of Examples 23 to 26, as shown in the figure. Figure 5 As shown. Figure 5 It can be seen that the sheets obtained in Example 23 and Example 24 were both burned through by the flame. The burning resistance of the sheet obtained in Example 26 was improved to a certain extent compared with that of the sheet obtained in Example 23 and Example 24, but still could not pass the UL 94-5VA test. Only the sheet obtained in Example 25 had a high flame retardant efficiency and passed the UL 94-5VA test.

[0116] The present invention also tested the mechanical properties of the modified PVC sheets obtained in Examples 1 to 26 above, which achieved a UL94-5VA flame retardant rating. The results are as follows:

[0117] Table 7

[0118]

[0119]

[0120] The mechanical, cold-resistant, and heat-resistant properties of the modified PVC sheets prepared in Examples 1 to 26 all met the data requirements in Table 7. As the amount of the compounded flame retardant increased, the tensile strength and elongation at break parameters decreased slightly, but remained within the required range for the application. All of the samples in the examples passed the cold-resistant, high and low temperature resistance, frozen ball impact, and heat resistance tests.

[0121] In summary, the innovation of the present invention lies in the use of environmentally friendly flame retardants, which will not cause environmental pollution. More importantly, the composition and ratio of the components of the compound flame retardant described in the present invention are reasonably selected, and the synergistic mechanism between the components is obvious, which greatly improves the fire resistance of the modified PVC sheet. Only 25wt% addition can make a 2mm PVC sheet pass the UL94-5VA test. Compared with traditional PVC sheets, the modified PVC sheet provided by the present invention passes the highest 5VA level in the UL94 flame retardant level test, showing excellent flame retardancy.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A modified PVC sheet that reaches UL94-5VA flame retardant grade, wherein the thickness of the modified PVC sheet is less than or equal to 8 mm; characterized in that: The raw materials for preparing the modified PVC sheet are mainly composed of PVC and flame retardant; The flame retardant includes one or a combination of two or more of flame retardant X, flame retardant Y, and porcelain-forming agent; The flame retardant X comprises one or a combination of two or more of ammonium polyphosphate, decabromodiphenylethane, aluminum hypophosphite, diethyl aluminum hypophosphite, and a carbonizing agent; The flame retardant Y comprises one or a combination of two or more of antimony trioxide, magnesium hydroxide, aluminum hydroxide or metal phosphate compounds; The porcelain-forming agent comprises one or a combination of two or more of low-melting-point glass powder, chopped glass fiber, mica flakes, kaolin and zinc borate.

2. The modified PVC sheet material having a flame retardant grade of UL94-5VA according to claim 1, characterized in that: The flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the flame retardant X accounts for less than 20% of the sum of the mass of the flame retardant and the PVC; Alternatively, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the flame retardant Y accounts for less than 30% of the sum of the mass of the flame retardant and the PVC; Alternatively, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC, and the porcelain-forming agent accounts for less than 20% of the total mass of the flame retardant and the PVC.

3. The modified PVC sheet having a flame retardant grade of UL94-5VA according to claim 1 or 2, characterized in that: When the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, the flame retardant accounts for more than 30% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide in a mass ratio of 6.5-7.5:1.5-2.5:0.5-1.

5.

4. The modified PVC sheet having a flame retardant grade of UL94-5VA according to claim 1 or 2, characterized in that: When the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, the flame retardant further includes a flame retardant X mainly composed of aluminum hypophosphite and decabromodiphenylethane; preferably, the mass ratio of the flame retardant Y to the flame retardant X is 3.5-4.5:0.5-1.

5.

5. The modified PVC sheet having a flame retardant grade of UL94-5VA according to claim 1 or 2, characterized in that: When the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate, the flame retardant accounts for more than 10% of the total mass of the flame retardant and the PVC; preferably, the flame retardant is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate in a mass ratio of 1.5-2.5:6.5-7.5:0.5-1.

5.

6. The modified PVC sheet having a flame retardant grade of UL94-5VA according to claim 1 or 2, characterized in that: When the flame retardant is mainly composed of chopped glass fibers, low-melting point glass powder and mica flakes, the flame retardant accounts for more than 10% of the total mass of the flame retardant and PVC; preferably, the flame retardant is mainly composed of chopped glass fibers, low-melting point glass powder and mica flakes in a mass ratio of 4-4.5:4.5-3.5:0.5-1.

7. The modified PVC sheet having a flame retardant grade of UL94-5VA according to claim 1 or 2, characterized in that: The flame retardant comprises 2 to 10 parts of flame retardant X, 0 to 14 parts of flame retardant Y and 0 to 10 parts of porcelain-forming agent, and the flame retardant Y and the porcelain-forming agent are not both 0; Preferably, the flame retardant X is mainly composed of ammonium polyphosphate and a char-forming agent, or the flame retardant X is mainly composed of aluminum hypophosphite and decabromodiphenylethane; further preferably, the flame retardant X is mainly composed of aluminum hypophosphite and decabromodiphenylethane in a mass ratio of 7 to 9:3 to 1, or the flame retardant X is mainly composed of ammonium polyphosphate and a char-forming agent in a mass ratio of 8 to 9:2 to 1; The porcelain-forming agent is mainly composed of chopped glass fibers and low-melting-point glass powder, or the porcelain-forming agent is mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes; further preferably, the porcelain-forming agent is mainly composed of chopped glass fibers and low-melting-point glass powder in a mass ratio of 7-9:3-1, or the porcelain-forming agent is mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes in a mass ratio of 4-4.5:4.5-3.5:0.5-1; The flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, or the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate; further preferably, the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide in a mass ratio of 6.5-7.5:1.5-2.5:0.5-1.5, or the flame retardant Y is mainly composed of magnesium hydroxide, aluminum hydroxide and zirconium phosphate in a mass ratio of 1.5-2.5:6.5-7.5:0.5-1.

5.

8. The modified PVC sheet having a flame retardant grade of UL94-5VA according to claim 1 or 2, characterized in that: The flame retardant is mainly composed of the following components: A flame retardant X mainly composed of ammonium polyphosphate and a carbon former, a flame retardant Y mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, and a porcelain former mainly composed of chopped glass fibers and low-melting-point glass powder; the mass ratio of the flame retardant X, the flame retardant Y and the porcelain former is 7.5-8.5:11.5-12.5:4.5-5.5; preferably, the flame retardant accounts for more than 25% of the total mass of the flame retardant and the PVC; Alternatively, the flame retardant is mainly composed of the following components: A flame retardant X mainly composed of ammonium polyphosphate and a carbon-forming agent, a flame retardant Y mainly composed of magnesium hydroxide, aluminum hydroxide and antimony trioxide, and a porcelain-forming agent mainly composed of chopped glass fibers, low-melting-point glass powder and mica flakes; the mass ratio of the flame retardant X, the flame retardant Y and the porcelain-forming agent is 3.5-4.5:7.5-8.5:2.5-3.5; preferably, the flame retardant accounts for more than 20% of the total mass of the flame retardant and the PVC.

9. A method for preparing the modified PVC sheet having a flame retardant grade of UL94-5VA as claimed in any one of claims 1 to 8.

10. Use of the modified PVC sheet having a flame retardancy of UL94-5VA according to any one of claims 1 to 8 in the fields of microelectronics, electronic appliances, wires and cables, and automobiles.

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