High flame-retardant low-smoke low-odor PVC ceiling membrane and preparation method thereof

Abstract

The application belongs to the technical field of PVC ceiling membranes, and particularly relates to a high-flame-retardant low-smoke low-odor PVC ceiling membrane and a preparation method thereof. The PVC ceiling membrane uses alkyl phosphate ester flame retardant, inorganic flame retardant, and liquid rubber with non-essential flame-retardant structure, significantly improves the flame-retardant and smoke-suppressing performance of the product, and meets the environmental protection requirements. In addition, the introduction of porous silicate substances plays a good deodorization effect, so that the prepared product has the comprehensive advantages of high flame retardancy, low smoke and low odor, and has good industrialization and popularization value.

Description

Technical Field

[0001] This invention belongs to the field of PVC ceiling film technology, specifically relating to a high flame retardant, low smoke, and low odor PVC ceiling film and its manufacturing method. Background Technology

[0002] Polyvinyl chloride (PVC) flexible films typically contain flammable plasticizers in their formulations, releasing large amounts of toxic fumes during combustion, posing a serious threat to people's escape in fire scenarios. As indoor environmental requirements for fire resistance and environmental standards continue to increase, PVC ceiling films used in decoration face multiple demands, including high flame retardancy, low smoke release, low odor, and environmental friendliness. The EU market, in particular, has stringent regulations on flame retardancy, explicitly requiring materials to significantly reduce the release of toxic and harmful fumes while achieving highly effective flame retardancy.

[0003] The odor of flame-retardant PVC film mainly comes from PVC raw materials and processing, such as volatile substances produced by the decomposition of flame retardants (e.g., organophosphorus flame retardants) and residual organic solvents in stabilizers. These substances release irritating odors that can affect indoor air quality and may cause respiratory discomfort, especially in sensitive places such as hospitals and hotels, where the harm is greater.

[0004] In the prior art, patent document CN117020780A discloses a PVC ceiling film that uses inorganic flame retardants such as antimony trioxide. However, it is known in the art that when flame retardants, especially halogenated flame retardants and antimony trioxide, are added to polymers, more smoke and toxic gases are produced during combustion. The hazards of smoke and toxic gases in a fire are greater than the high temperature itself. Patent document CN119955234A discloses a PVC rear projection film that uses specific phosphate ester flame retardants and inorganic flame retardants to achieve a synergistic flame retardant effect. However, phosphate ester flame retardants also have the problem of producing smoke and toxic and corrosive gases. Patent document CN113004640A discloses a PVC film and its preparation method. Through the synergistic effect of the compounding of flame retardant plasticizers (containing tri(2-chloropropyl) phosphate and isopropylated triphenyl phosphate) and nanofillers, and by precisely controlling the process temperature parameters, it successfully achieves the synergistic optimization of high flame retardancy and processing stability of flexible PVC film. However, the flame retardant triphenyl isopropyl phosphate (IPPP) used in this system has been classified as a Substance Subject to Authorization (SVHC) under the EU REACH regulation due to its environmental persistence, bioaccumulation, and ecotoxicity, and its use is strictly restricted. Furthermore, while the patent achieves a B1 flame retardant rating, the issue of unresolved concerns regarding the release of toxic fumes remains unresolved.

[0005] As the above analysis shows, it is extremely difficult for existing PVC membrane materials to achieve an effective balance between flame retardancy and low smoke and odor. Currently, very few PVC membrane materials can meet the flame retardancy requirement of Class B in EN13501-1:2018 while simultaneously achieving a smoke generation level of S2.

[0006] Organophosphate compounds, widely used as flame retardant materials in ceiling film systems, exhibit excellent char-forming properties. However, experimental studies have found that the formation of a high-quality char layer has limited effect on inhibiting smoke generation in flexible ceiling films. Compared to intumescent flame retardant systems, in PVC film systems, the sustained barrier properties of the char layer against flame smoke may actually lead to insufficient structural stability of the char layer. This instability exacerbates the incomplete combustion of volatile organic combustibles in flexible films, resulting in the generation of larger amounts of toxic smoke and significantly weakening the overall smoke suppression performance of ceiling film materials.

[0007] Therefore, obtaining a highly flame-retardant, low-smoke, low-odor, and environmentally friendly PVC ceiling film is of paramount importance in the development of new products in this field. Summary of the Invention

[0008] To address the above problems, the purpose of this invention is to provide a high flame-retardant, low-smoke, and low-odor PVC ceiling film and its manufacturing method. The solution of this invention is as follows:

[0009] A high flame-retardant, low-smoke, and low-odor PVC ceiling film is made from the following materials by weight: 100 parts PVC resin powder, 2-10 parts cold-resistant plasticizer, 15-45 parts environmentally friendly plasticizer, 8-45 parts composite flame retardant, 2-8 parts stabilizer, 0.5-5 parts epoxidized soybean oil, 0-40 parts inorganic filler, 5-20 parts titanium dioxide, 0.5-10 parts liquid rubber, 0.1-3 parts deodorizer, and 0.1-3 parts processing aid; the composite flame retardant is composed of alkyl phosphate flame retardants and inorganic flame retardants; the liquid rubber is a non-intrinsically flame-retardant liquid rubber. It is known in the art that intrinsic flame retardancy refers to the presence of flame-retardant atoms or groups (such as nitrogen, silicon, phosphorus, and halogens) in the polymer main chain or side chain. When the polymer material is heated and burns, these atoms undergo a chemical reaction to produce flame-retardant gases, thereby inhibiting the spread of fire. Therefore, the liquid rubber referred to in the term "liquid rubber with non-intrinsic flame-retardant structure" does not contain atoms or groups with flame-retardant effects (such as nitrogen, silicon, phosphorus and halogens).

[0010] Preferably, the liquid rubber with the non-intrinsic flame-retardant structure is selected from one or more of liquid hydroxyl-terminated polybutadiene rubber, liquid nitrile rubber, and liquid polyisoprene rubber.

[0011] Preferably, the alkyl phosphate flame retardant is selected from one or more of triethyl phosphate, tris(butoxyethyl) phosphate, tributyl phosphate, and dimethyl phosphate.

[0012] Preferably, the inorganic flame retardant is selected from one or more of antimony trioxide, talc, and zinc borate.

[0013] Preferably, the weight ratio of alkyl phosphate flame retardant to inorganic flame retardant in the composite flame retardant is (1~4):(1~3). More preferably, the weight ratio of alkyl phosphate flame retardant to inorganic flame retardant in the composite flame retardant is one of 1:1 or 4:3.

[0014] Preferably, the deodorizing agent is selected from one or more of diatomaceous earth (silicate), zeolite, and kaolin (aluminosilicate).

[0015] Preferably, the cold-resistant plasticizer is dioctyl adipate; the environmentally friendly plasticizer is dioctyl terephthalate.

[0016] Preferably, the inorganic filler is one or more of PVC-specific calcium, ultra-white calcium, and nano-calcium.

[0017] Preferably, the processing aid is selected from one or more acrylic processing aids, such as PA-40 and LP-40.

[0018] The present invention also provides a method for preparing the aforementioned PVC ceiling film, comprising the following steps: taking materials, mixing the materials as a premix, cooling, extruding, plasticizing, filtering, calendering, embossing, cooling again, cutting, and winding; the process temperature for mixing the materials is 90℃~120℃; the process temperature for extrusion is 175℃~210℃; the process temperature for plasticizing is 160℃-190℃; and the process temperature for calendering is 130℃~200℃.

[0019] Beneficial effects:

[0020] The beneficial effects of this invention are as follows: Addressing the difficulties encountered in the use of existing PVC ceiling films—such as environmental unfriendliness, flammability, high smoke production during combustion, and strong odor—this invention constructs a synergistic flame-retardant system combining alkyl phosphate organic flame retardants and inorganic flame retardants, and introduces elastic liquid rubber. The PVC ceiling film shrinks upon exposure to fire, significantly reducing fire spread and effectively decreasing the generation of toxic fumes. Furthermore, the addition of silicate-based deodorizing agents improves the odor problem of traditional ceiling films. This results in a ceiling film that possesses both flame-retardant properties and excellent smoke suppression and low odor effects, providing a safety guarantee for the application of ceiling films in the construction field. Detailed Implementation

[0021] The following detailed embodiments further illustrate the solution and effects of the present invention. It should be understood that these embodiments are merely for demonstrating the implementation and effects of the present invention and are not intended to limit the scope of the invention. After reading the contents of this invention, those skilled in the art can make various simple modifications or alterations to the invention without creative effort, and these equivalent / identical transformations also fall within the protection scope of this invention.

[0022] To ensure comparability between the experimental examples and Comparative Example 1, the PVC resin powder used in the following experimental examples and comparative examples was SG-5 type resin powder with a degree of polymerization of 1000; the environmentally friendly plasticizer was dioctyl terephthalate (DOTP) from the same commercial source; the cold-resistant plasticizer was dioctyl adipate (DOA) from the same commercial source; the titanium dioxide was rutile titanium dioxide from the same commercial source (residue ≤0.01% on a 45μm sieve); the inorganic filler was PVC-specific calcium (3000 mesh) from the same commercial source; the processing aid was acrylic processing aid (PA-40) from the same commercial source; and the talc was ultrafine talc (5000 mesh) from the same commercial source. Other materials with the same name were also from the same commercial source and of the same specification.

[0023] Example 1: Formulation and preparation of different PVC ceiling films

[0024] This embodiment demonstrates the formulation and preparation methods of various PVC ceiling films, including the ceiling film of the present invention (experimental example) and other ceiling films investigated during the exploration process (comparative examples). The formulations of different PVC ceiling films can be found in Tables 1 and 2.

[0025] Table 1. Ingredients of PVC Ceiling Film in Different Experimental Examples

[0026] Table 2. Ingredients of PVC Ceiling Films in Different Comparative Examples

[0027] Note: (1) The composition of the composite flame retardant in Experiments 1 to 6 in Table 1 (by weight) is as follows: 15 parts of triethyl phosphate + 10 parts of antimony trioxide + 5 parts of talc; 10 parts of tri(butoxyethyl) phosphate + 10 parts of triethyl phosphate + 12 parts of antimony trioxide + 3 parts of talc; 15 parts of triethyl phosphate + 5 parts of tri(butoxyethyl) phosphate + 15 parts of antimony trioxide + 5 parts of talc; 15 parts of triethyl phosphate + 5 parts of tri(butoxyethyl) phosphate + 12 parts of antimony trioxide + 8 parts of talc; 15 parts of triethyl phosphate + 5 parts of tri(butoxyethyl) phosphate + 15 parts of antimony trioxide + 5 parts of talc; 15 parts of triethyl phosphate + 5 parts of tri(butoxyethyl) phosphate + 20 parts of antimony trioxide.

[0028] (2) The flame retardant compositions (by weight) of Comparative Examples 1-5 in Table 2 are as follows: 30 parts of diphenyl toluene phosphate (a halogen-free aromatic phosphate liquid product, with a triphenyl phosphate content of up to 11.9%); 30 parts of tri-(1,3-dichloroisoethyl) phosphate; 10 parts of aluminum hydroxide + 16 parts of antimony trioxide + 7 parts of zinc borate + 7 parts of wollastonite; 30 parts of diphenyl toluene phosphate; 15 parts of triethyl phosphate + 5 parts of tri(butoxyethyl) phosphate + 20 parts of antimony trioxide.

[0029] (3) The elastic rubbers in Experimental Examples 1 to 6 and Comparative Example 5 in Tables 1 and 2 are liquid hydroxyl-terminated polybutadiene rubber, liquid nitrile rubber, liquid nitrile rubber, liquid hydroxyl-terminated polybutadiene rubber, liquid nitrile rubber, liquid hydroxyl-terminated polybutadiene rubber, and liquid silicone rubber, respectively.

[0030] (4) In Tables 1 and 2, “silicon” refers to diatomaceous earth, “boil” refers to zeolite, and “high” refers to kaolin.

[0031] The preparation methods of different PVC ceiling films in this study are as follows (when a certain material is lacking in the comparative example, the corresponding material addition step is omitted):

[0032] Sample preparation employed conventional techniques in the field. The overall preparation steps included: taking materials according to the proportions in Tables 1 and 2; mixing the materials as a premix; cooling; extrusion; plasticizing; filtering; calendering; embossing; re-cooling; cutting; and winding. The mixing temperature was 110℃. Cooling involved pre-impregnating the premix in a feeding hopper (at room temperature); then processing the cooled material in a planetary extruder at 180℃, followed by plasticizing in a rolling mill at 175℃, and filtering out impurities using a filter screen; finally, calendering in a calendering roller assembly; and re-cooling after embossing. The final product was then cut and wound to obtain the PVC ceiling film. The prepared ceiling film thickness was 0.20 mm.

[0033] Example 2: Performance Testing and Comparison of Different Ceiling Films

[0034] This embodiment is used to record and demonstrate the performance test results of different ceiling films in Example 1.

[0035] (1) Flame retardancy and smoke suppression test: The flame retardancy performance of the prepared PVC ceiling film was tested according to EN13501-1:2018 (Fireclassification of construction products and building elements - Part 1: Classification using data from reaction to fire tests); including EN13823 (Single ignition test of building materials or products, SBI) and EN ISO 11925-2 (Tests on flammability of building materials, Part 2: Single ignition source test). The EN13823 standard classifies building products into 7 main grades (A1, A2, B, C, D, E, F), with A1 having the highest fire resistance and F the lowest. Smoke generation rating (s1-s3) and burning droplet rating (d0-d2): can be obtained from the test data SMOGRA and TSP. 600s The flame retardant and smoke suppression properties of the prepared ceiling film are determined by: (SMOGRA - Smoke Generation Rate (m)) 2 / s 2 ), TSP 600s - Total flue gas production at 600 seconds (m³) 2 The EN13823 testing standard specifies S1 level: SMOGRA < 30m 2 / s 2 And TSP 600s <50m 2 S2 level: SMOGRA < 180m 2 / s 2 And TSP 600s <200m 2 。

[0036] (2) Odor irritation level test:

[0037] Odor testing was conducted using a blind method. Equal amounts of samples were treated in the same manner, and then five evaluators who were unaware of the grouping of the test samples scored the intensity of the odor (1-9 points: 1-3 points for mild; 4-6 points for strong; 7-9 points for pungent). The intensity of the odor for each sample was graded based on the average score of the five evaluators.

[0038] The odor characteristics of the ceiling film of this invention are tested using a high-temperature accelerated aging odor test method. The specific operation procedure is as follows: a quantitative sample of ceiling film is cut, sealed and wrapped with tin foil, and placed in an 80°C constant temperature oven for 2 hours of heat aging treatment. After the sample cools to room temperature, its odor intensity level is evaluated by sensory olfaction.

[0039] (3) Environmental Assessment: The environmental assessment standard is the REACH standard. A systematic verification of the product's environmental performance was conducted. Testing was performed according to the relevant requirements of the EU REACH regulation (Registration, Evaluation, Authorisation and Restriction of Chemicals), using the testing method referenced IEC 62321, to assess the chemical safety of the prepared ceiling film. The testing focused on confirming whether the sample contained any substances listed in the REACH Substances of Very High Concern (SVHC) candidate list, and whether the mass fraction of any single substance or similar substances exceeded the regulatory limit of 0.1%.

[0040] The test results for each sample are shown in Tables 3 and 4.

[0041] Table 3 Performance test results of experimental samples

[0042] Table 4 Performance test results of comparative samples

[0043] The main differences between the experimental and comparative samples in this study lie only in the deodorizer, flame retardant, and elastic rubber (liquid rubber). Table 3 shows that the experimental products meet the requirements for flame retardancy, odor irritation, and environmental friendliness, exhibiting advantages such as high flame retardancy, low smoke, and low odor. In contrast, the comparative products have poorer flame retardancy, and most have stronger odors or do not meet environmental requirements; their overall performance is inferior to that of the experimental samples.

[0044] Although Comparative Example 4 also used diatomaceous earth as an odor remover, its flame retardant and smoke suppression properties were poor. Comparative Example 5, while using elastic rubber, and although silicone rubber has some flame retardant properties, could not effectively synergize with the system of this ceiling film, resulting in flame retardant and smoke suppression properties far inferior to the ceiling film of this invention. Besides flame retardancy and smoke suppression, the choice of flame retardant also affects environmental friendliness (problems such as excessively high TPP content). It is evident that the selection of materials has complex implications for achieving high flame retardancy, low smoke, and low odor in PVC ceiling films.

[0045] Firstly, regarding flame retardancy and smoke suppression, the experimental samples, using a combination of specific phosphate ester organic flame retardants and inorganic flame retardants (i.e., using composite flame retardants), effectively improved flame retardancy, environmental friendliness, and low smoke performance. Composite flame retardants using alkyl phosphates (such as triethyl phosphate and tris(butoxyethyl) phosphate) and inorganic combustion improvers (such as antimony trioxide and ultrafine talc) showed good advantages in terms of environmental friendliness, flame retardancy, and low smoke. However, when elastic rubber (liquid rubber) is missing (as in Comparative Examples 1-4), the flame retardancy and smoke suppression performance of the products still decrease significantly. Even with elastic rubber (liquid rubber), difficult exploration is needed to obtain optimal material types to further significantly improve the flame retardancy and smoke suppression performance of the products (Experimental Example vs. Comparative Example 5). While the liquid silicone rubber in the elastic rubber (Comparative Example 5) possesses inherent flame retardancy, it is difficult to exert its full effect due to poor synergy with the system. Liquid elastic rubbers (liquid hydroxyl-terminated polybutadiene rubber, liquid nitrile rubber) that are not intrinsically flame-retardant are more likely to quickly block the spread of fire sources, significantly improving the flame-retardant and smoke-suppressing effects of the product.

[0046] As can be seen from Experiments 1-6, under the condition of constant addition of composite flame retardant, with the increase of the proportion of elastic rubber (liquid rubber), the smoke generation rate (SMOGRA) and the total smoke volume (TSP) during material combustion increase. 600s All showed a regular downward trend and were relatively stable. The flame torch test (using a flame torch to simulate actual combustion, with the sample surface ignited for 10 seconds to compare charring) also showed that the morphology of the char layer after combustion of the ceiling film of this invention exhibited a regular circular pore state. The film quickly burned through after encountering a flame source, forming a stable char layer around the flame. The synergistic effect of liquid rubber and alkyl phosphate esters induced directional shrinkage of the film through molecular chain rearrangement. The liquid rubber preferentially decomposed during combustion and rapidly participated in the combustion process, significantly reducing combustible residues. The synergistic effect of liquid rubber and phosphate esters enabled the PVC film to exhibit controllable shrinkage in the flame.

[0047] By comparing the experimental data of Example 6 and Comparative Example 5, it can be found that the total smoke volume (TSP) of PVC ceiling film using conventional flame-retardant liquid silicone rubber during combustion is significantly lower in 600 seconds. 600s The smoke generation rate increased significantly. This phenomenon can be attributed to the fact that its flame-retardant mechanism mainly relies on the formation of a condensed phase protective layer, and achieves flame-retardant performance through synergistic charring with the PVC matrix. However, while this charring mechanism prolongs the flame contact time, it also intensifies the continuous contact between the char layer and the flame, leading to a significant increase in the smoke generation rate. In contrast, the non-flame-retardant liquid hydroxyl-terminated polybutadiene rubber system used in Example 6 exhibits excellent smoke-suppressing properties. The experimental results provide strong support for the flame-retardant strategy proposed in this invention, which shrinks upon contact with fire, reduces the fire-exposed area, and thus significantly reduces the amount of smoke released.

[0048] Secondly, regarding environmental protection, the comparative analysis of the test data in Tables 3 and 4 shows that, compared with Comparative Examples 1 and 2, the raw materials used in this invention do not contain substances of very high concern. The ceiling film samples prepared in Examples 1-6 showed no detectable substances listed in the SVHC control list, and the measured mass fractions of each target substance were significantly lower than the regulatory threshold of 0.1%. This result indicates that the ceiling film described in this invention fully meets the REACH regulatory requirements in terms of chemical substance control, and has a significant advantage in environmental friendliness compared to traditional flame-retardant PVC ceiling films.

[0049] Finally, from an environmentally friendly perspective, controlling product odor is crucial for applications in interior decoration.

[0050] For ceiling film materials, significant odor is crucial, as it constitutes a core defect in their practical application. Based on the test data in Tables 3 and 4, it is evident that the samples in Comparative Examples 1 and 2, prepared using organophosphate flame retardants, all exhibited significant odor. The introduction of organophosphate flame retardants exacerbated the product odor problem. However, a comparison between the comparative examples and experimental cases shows that diatomaceous earth and its combinations with zeolite, kaolin, and other materials significantly contribute to reducing product odor. This invention uses diatomaceous earth (a porous silicate), which can effectively remove most odor molecules through a synergistic effect of physical adsorption and chemical decomposition. Comparing the odor test data of Example 1 and Comparative Example 4 shows that the porous silicate deodorizing functional additive diatomaceous earth has a good deodorizing effect. Furthermore, the verification results in Examples 1-6 demonstrate that the ceiling film samples with added porous silicate deodorizing agents exhibit superior odor control performance, significantly improving the overall product quality. Moreover, the prepared products showed no other quality problems, indicating that the deodorizing agent is well-suited to the flame retardant system and can synergistically optimize the environmental adaptability of the material.

Claims

1. A high flame-retardant, low-smoke, and low-odor PVC ceiling film, characterized in that, The PVC ceiling film, by weight, is made from the following materials: 100 parts PVC resin powder, 2-10 parts cold-resistant plasticizer, 15-45 parts environmentally friendly plasticizer, 8-45 parts composite flame retardant, 2-8 parts stabilizer, 0.5-5 parts epoxidized soybean oil, 0-40 parts inorganic filler, 5-20 parts titanium dioxide, 0.5-10 parts liquid rubber, 0.1-3 parts deodorizer, and 0.1-3 parts processing aid; the composite flame retardant is composed of alkyl phosphate flame retardant and inorganic flame retardant; the liquid rubber is selected from one or more of liquid hydroxyl-terminated polybutadiene rubber, liquid nitrile rubber, and liquid polyisoprene rubber; and the inorganic flame retardant is selected from one or more of antimony trioxide and talc.

2. The high flame retardant, low smoke, and low odor PVC ceiling film according to claim 1, characterized in that, The alkyl phosphate flame retardant is selected from one or more of triethyl phosphate, tris(butoxyethyl) phosphate, tributyl phosphate, and dimethyl phosphate.

3. The high flame retardant, low smoke, and low odor PVC ceiling film according to claim 1, characterized in that, The weight ratio of alkyl phosphate flame retardant to inorganic flame retardant in the composite flame retardant is (1~4):(1~3).

4. The high flame retardant, low smoke, and low odor PVC ceiling film according to claim 1, characterized in that, The deodorizing agent is selected from one or more of diatomaceous earth, zeolite, and kaolin.

5. The high flame retardant, low smoke, and low odor PVC ceiling film according to claim 1, characterized in that, The cold-resistant plasticizer is dioctyl adipate; the environmentally friendly plasticizer is dioctyl terephthalate.

6. The high flame retardant, low smoke, and low odor PVC ceiling film according to claim 1, characterized in that, The inorganic filler is one or more of the following: PVC-specific calcium, ultra-white-specific calcium, and nano-calcium.

7. The high flame retardant, low smoke, and low odor PVC ceiling film according to claim 1, characterized in that, The processing aid is selected from one or more of the acrylic processing aids PA-40 and LP-40.

8. A method for preparing a high flame-retardant, low-smoke, and low-odor PVC ceiling film according to any one of claims 1-7, comprising the following steps: taking materials, mixing the materials as a premix, cooling, extruding, plasticizing, filtering, calendering, embossing, re-cooling, cutting, and winding; wherein the process temperature for mixing the materials is 90℃~120℃; the process temperature for extrusion is 175℃~210℃; the process temperature for plasticizing is 160℃-190℃; and the process temperature for calendering is 130℃~200℃.

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