Novel lignin flame retardant, preparation method thereof and preparation method of modified PBT (Polybutylece Terephthalate) plastic

Abstract

The invention belongs to the technical field of high polymer materials, and particularly discloses a novel lignin flame retardant, a preparation method and a preparation method of modified PBT (polybutylene terephthalate) plastic. The preparation method of the novel lignin flame retardant comprises the following steps: dissolving sodium antimonate in tartaric acid to form a first solution; uniformly distributing the first solution in lignin powder to prepare an antimony-containing lignin flame-retardant synergist; the antimony-containing lignin flame retardant synergist and a brominated flame retardant are uniformly mixed to prepare the novel lignin flame retardant. Sodium antimonate is dissolved in tartaric acid, then lignin is added, a large number of active groups in lignin react with the tartaric acid, the flame retardant effect is improved, and the prepared antimony-containing lignin flame retardant synergist is high in flame retardance and high in preparation efficiency. Lignin is a natural polymer and is extremely low in utilization rate, and when the lignin is used as a flame retardant component to replace part of sodium antimonate, the lignin has a good environment-friendly effect and is relatively low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a new lignin flame retardant, a preparation method thereof, and a preparation method of modified PBT plastic. Background Art

[0002] PBT plastic refers to a type of plastic composed mainly of polybutylene terephthalate. PBT is one of the five major engineering plastics. Its English name is polybutylene terephthalate (PBT for short), which belongs to the polyester series. It is made by the polycondensation of 1,4-butanediol and terephthalic acid (PTA) or dimethyl terephthalate (DMT). PBT is a semi-crystalline thermoplastic polyester. It has high heat resistance, toughness, fatigue resistance, self-lubrication, low friction coefficient, is not resistant to strong acids and strong alkalis, is resistant to organic solvents, and is flammable and decomposes at high temperatures. It has been widely used in automobiles, mechanical equipment, precision instrument parts, electronic appliances, textiles and other fields.

[0003] During the PBT preparation process, we perform various modifications on it, adding various additives to prepare PBT materials with different properties to compensate for the performance deficiencies of the PBT material. This technology uses a new flame retardant formula to improve the flame retardancy of the PBT material without changing the other properties of the PBT material. The role of the flame retardant is to give flammable polymers a functional additive with flame retardancy, and is mainly designed for the flame retardancy of polymer materials. There are many types of flame retardants, which are divided into additive flame retardants and reactive flame retardants according to the method of use. They are generally divided into organic flame retardants and inorganic flame retardants. The present invention uses commonly used flame retardants in the laboratory to mix and prepare a new composite flame retardant to prepare a new PBT material with better flame retardancy.

[0004] Flame retardants primarily include organic and inorganic, halogen and non-halogen. Organic flame retardants are represented by bromine, nitrogen, red phosphorus, and their compounds, while inorganic flame retardants primarily include antimony trioxide, magnesium hydroxide, aluminum hydroxide, and silicon-based flame retardants. Generally speaking, organic flame retardants have excellent affinity for plastics, and brominated flame retardants hold a dominant position among organic flame retardant systems. Despite numerous environmental concerns, they remain difficult to replace with other flame retardant systems.

[0005] Therefore, existing flame retardants have disadvantages such as low flame retardancy, high cost, low preparation efficiency, and environmental pollution.

[0006] Based on the above problems, the present invention intends to provide a new lignin flame retardant, a preparation method and a preparation method of modified PBT plastic. Summary of the Invention

[0007] (1) Technical issues to be solved

[0008] The present application aims to provide a novel lignin flame retardant, a preparation method and a preparation method of modified PBT plastic, so as to solve the problems of low flame retardancy, low preparation efficiency, high cost and environmental pollution of the prior art.

[0009] (II) Technical scheme

[0010] To solve the above technical problems, the present application provides a novel lignin flame retardant, and the required raw materials are prepared according to the following weight parts:

[0011] The first brominated epoxy resin flame retardant: 2-3 parts;

[0012] The brominated polystyrene flame retardant: 2-3 parts;

[0013] The second brominated epoxy resin flame retardant: 2-3 parts;

[0014] The third brominated epoxy resin flame retardant: 2-3 parts;

[0015] Sodium antimonate: 2-3 parts;

[0016] Lignin: 10-15 parts.

[0017] On the other hand, a preparation method of a novel lignin flame retardant is provided, which comprises the following steps:

[0018] Dissolve sodium antimonate in tartaric acid to form a first solution;

[0019] Uniformly distribute the first solution in lignin powder to prepare a lignin flame-retardant synergist containing antimony;

[0020] Mix the lignin flame-retardant synergist containing antimony with the bromine-based flame retardant uniformly to prepare a novel lignin flame retardant.

[0021] Among them, the bromine-based flame retardant includes brominated epoxy resin flame retardant and brominated polystyrene flame retardant.

[0022] Among them, the brominated epoxy resin flame retardant includes the first brominated epoxy resin flame retardant, the second brominated epoxy resin flame retardant, the third brominated epoxy resin flame retardant, and the brominated polystyrene flame retardant is the brominated polystyrene flame retardant.

[0023] Among them, the required raw materials for preparing the novel lignin flame retardant are prepared according to the following weight parts:

[0024] The first brominated epoxy resin flame retardant: 2-3 parts;

[0025] The brominated polystyrene flame retardant: 2-3 parts;

[0026] The second brominated epoxy resin flame retardant: 2-3 parts;

[0027] Third brominated epoxy resin flame retardant: 2-3 parts;

[0028] Sodium antimonate: 2-3 parts;

[0029] Lignin: 10-15 parts.

[0030] The lignin is formed by three phenylpropane units being connected to each other by ether bonds and carbon-carbon bonds, the lignin has a three-dimensional network structure, and the lignin contains aromatic ring structures, aliphatic and aromatic hydroxyl groups, and active groups of quinone groups.

[0031] The raw materials required for preparing the novel lignin flame retardant are added into a mixing bag in a proportion by weight, and then uniformly mixed by using a high-speed mixer.

[0032] In another aspect, a preparation method of modified PBT plastic is provided, comprising the following steps:

[0033] The main material PBT and the toughening agent are added into a high-speed mixer for high-speed premixing by heating;

[0034] The novel lignin-based flame retardant according to claims 1-6 is fed into a double-screw extruder through a side feeder, and the premixed main material PBT and the toughening agent are simultaneously fed into the double-screw extruder;

[0035] Then, the mixed material of the main material PBT, the toughening agent and the novel lignin-based flame retardant is mixed by using a double-screw extruder;

[0036] The mixed material is subjected to mixing, shearing, dispersing and filtering to obtain the modified PBT plastic.

[0037] (III) Beneficial effects

[0038] The above technical solution of the present application has the following advantages:

[0039] In the present application, sodium antimonate is used as a flame-retardant synergist, is dissolved in tartaric acid to form a first solution, and the tartaric acid can undergo a metathesis reaction with the sodium antimonate to generate antimony acid and sodium tartrate, the first solution is uniformly distributed in the lignin powder, a novel antimony-containing flame-retardant synergist is prepared, and some functional groups in the lignin molecules can form a complex with antimony ions. This complexation can further change the existence state of the antimony ions in the solution, affect its chemical activity and solubility. In this way, the sodium antimonate is dissolved in the tartaric acid, and then the lignin is added, a large number of active groups in the lignin react with the sodium antimonate, so that the flame-retardant effect is increased, the prepared lignin flame-retardant synergist containing antimony has high flame-retardant property and high preparation efficiency. Moreover, the lignin is a natural polymer, and its utilization rate is extremely low. Using the lignin as a flame-retardant component to replace part of the sodium antimonate has good environmental protection effect and low cost. DETAILED DESCRIPTION

[0040] The technical solutions of the present application are described in further detail below. Those skilled in the art should understand that the specific embodiments are only to help understand the present application, and should not be considered as a specific limitation of the present application.

[0041] It should be noted that, if not specifically indicated, the technical means used in the following examples are conventional means known to those skilled in the art. When not specifically stated, the raw materials used in the present application are all commercially available conventional goods, which can be purchased.

[0042] The present application provides a new type of lignin flame retardant, the required raw materials are prepared according to the following weight parts:

[0043] CR-100K (first brominated epoxy resin flame retardant): 2-3 parts;

[0044] 7010 (brominated polystyrene flame retardant): 2-3 parts;

[0045] 225K (second brominated epoxy resin flame retardant): 2-3 parts;

[0046] CR-210K (third brominated epoxy resin flame retardant): 2-3 parts;

[0047] Sodium antimonate: 2-3 parts;

[0048] Lignin: 10-15 parts.

[0049] The preparation method of the new type of lignin flame retardant of the present application comprises the following steps:

[0050] Dissolve sodium antimonate in tartaric acid to form a first solution;

[0051] Uniformly distribute the first solution in lignin powder to prepare a sodium-containing lignin flame-retardant synergist;

[0052] Mix the sodium-containing lignin flame-retardant synergist with bromine-based flame retardant uniformly to prepare a new type of lignin flame retardant.

[0053] In the specific embodiments provided by the present application, sodium antimonate is dissolved in tartaric acid, and uniformly distributed in lignin powder to prepare a new type of sodium-containing flame-retardant synergist. In the blending system of PBT with brominated epoxy resin added in a certain proportion, the prepared modified PBT has no obvious influence on the uniform elongation at break, bending modulus, cantilever beam notched impact cantilever beam unnotched impact, shrinkage rate and other properties; the flame-retardant effect is similar to that of using a large amount of sodium-containing flame-retardant synergist. Among them, sodium antimonate is dissolved in tartaric acid, and then lignin is added. A large number of active groups in lignin react with it, so that the flame-retardant effect is increased.

[0054] In the present application, lignin is added to achieve the mechanism of flame-retardant replacement agent as follows:

[0055] (1) Formation of carbon layer

[0056] Mechanism explanation: During combustion, lignin undergoes thermal decomposition, which involves a series of chemical reactions such as dehydration and cross-linking, forming a dense carbon layer. This carbon layer acts as a physical barrier, preventing the transfer of heat, oxygen, and combustible gases, thereby slowing down the combustion rate.

[0057] (2) Release of non-combustible gases

[0058] Mechanism explanation: During pyrolysis, lignin releases some non-combustible gases such as carbon dioxide and water vapor. The release of these gases dilutes the concentration of combustible gases, reducing the intensity of the combustion reaction, and also carries away some heat, acting as a cooling effect.

[0059] (3) Capture of free radicals

[0060] Mechanism explanation: During combustion, a large number of free radicals are generated, which are active intermediates in the combustion reaction and can promote the progress of the combustion reaction. Some functional groups in lignin, such as phenolic hydroxyl groups and methoxyl groups, have the ability to capture free radicals, forming stable compounds through reaction with free radicals, thereby terminating the chain propagation of the combustion reaction.

[0061] (4) Promotion of carbonization reaction

[0062] Mechanism explanation: Lignin can synergize with other flame retardants or additives to promote the carbonization reaction of materials. For example, when lignin is used in combination with phosphorus-based flame retardants, the phosphorus-based flame retardants can promote the dehydration and carbonization of lignin, forming a more dense and stable carbon layer, thereby improving the flame retardant effect.

[0063] Based on the above mechanism, a certain amount of lignin is added in the PBT flame retardant modification to replace part of the traditional halogen-containing flame retardant system.

[0064] Specifically, the bromine-based flame retardant includes brominated epoxy resin flame retardant and brominated polystyrene flame retardant.

[0065] Specifically, the brominated epoxy resin flame retardant includes CR-100K, 225K, and CR-210K, and the brominated polystyrene flame retardant is 7010. CR-100K, 225K, and CR-210K are first, second, and third brominated epoxy resin flame retardants, respectively, all of which have good flame retardant properties.

[0066] The raw materials required for preparing the lignin-based novel flame retardant are prepared according to the following weight parts:

[0067] CR-100K: 2-3 parts;

[0068] 7010: 2-3 servings;

[0069] 225K: 2-3 servings;

[0070] CR-210K: 2-3 servings;

[0071] Sodium antimonate: 2-3 parts;

[0072] Lignin: 10-15 parts.

[0073] Among them, lignin is formed by three phenylpropane units connected to each other through ether bonds and carbon-carbon bonds. The lignin has a three-dimensional network structure and contains active groups such as aromatic ring structures, aliphatic and aromatic hydroxyl groups, and quinone groups.

[0074] The raw materials required for preparing the new lignin flame retardant are added into a mixing bag according to weight proportions and then mixed evenly using a high-speed mixer.

[0075] The present invention can use different brominated epoxy resins and lignin to replace part of the sodium antimonate to form a flame retardant.

[0076] In the technical solution of the above embodiment, regarding the principle of tartaric acid dissolving sodium antimonate:

[0077] Chemical Reaction Principle: Tartaric acid is an organic acid with a certain degree of acidity. Sodium antimonate is a weak acid salt. When tartaric acid and sodium antimonate come into contact, the acidity of tartaric acid is stronger than that of antimonic acid. Based on the principle of strong acid replacing weak acid, tartaric acid and sodium antimonate undergo a double decomposition reaction to form antimonic acid and sodium tartrate.

[0078] Analysis of the dissolution process: The generated antimonic acid has a certain solubility in water. At the same time, the change in the ionic state during the reaction also helps to destroy the original lattice structure of sodium antimonate, causing sodium antimonate to gradually dissolve in the tartaric acid solution.

[0079] Complexation after adding lignin: Certain functional groups in lignin molecules may form complexes with antimony ions. For example, hydroxyl groups in lignin can bind to antimony ions through coordination bonds, forming a relatively stable complex structure. This complexation can further alter the state of antimony ions in solution, affecting their chemical activity and solubility.

[0080] The dispersion and stabilization effect of lignin: Lignin's high molecular weight structure can act as a dispersant in solutions. It can adsorb onto the surface of particles of antimonic acid or other reaction products, preventing aggregation and precipitation, thereby improving solution stability. For example, in some colloidal systems, lignin can prevent particle collision and aggregation through steric hindrance, maintaining a uniform dispersion.

[0081] In the technical solution of the present invention, the preparation method of the modified PBT plastic comprises the following steps:

[0082] Add the main material PBT and toughening agent into the high-speed mixer and heat and pre-mix at high speed;

[0083] The above-mentioned new lignin flame retardant is fed into the twin-screw extruder through a side feeder, and the pre-mixed main material PBT and toughening agent are simultaneously fed into the twin-screw extruder;

[0084] Then the mixed material of main material PBT, toughening agent and new flame retardant based on lignin is extruded through a twin-screw extruder;

[0085] The mixed material is mixed, sheared, dispersed and filtered to obtain modified PBT plastic.

[0086] In the production process of PBT, the new lignin flame retardant is produced together with the main material PBT and toughening agent to prepare the finished PBT. The flame retardancy is greatly improved. While achieving the flame retardant effect efficiently, the original properties of PBT are not changed. The good plasticity can reduce the use rate of flame retardants and reduce costs.

[0087] In summary, the preparation method of the novel lignin flame retardant and the preparation method of the modified PBT plastic provided by the present invention have the following advantages.

[0088] 1. A new type of antimony-containing flame retardant synergist was prepared. When it was mixed with PBT in a certain proportion with brominated epoxy resin, the modified PBT had no significant effect on its uniform elongation at break, flexural modulus, notched Izod impact, unnotched Izod impact, shrinkage and other properties.

[0089] 2. Dissolve sodium antimonate in tartaric acid and then add lignin. The large number of active groups in the lignin react with it, increasing its flame retardant effect.

[0090] 3. The preparation method adopted by the invention is simple, has significantly improved flame retardant properties, and has the advantages of easy preparation, low cost, and high efficiency;

[0091] 4. The innovation of this invention is that the use of lignin as a flame retardant component improves the flame retardant properties of the flame retardant and enables other flame retardant components to perform better.

[0092] 5. Lignin is a natural polymer with extremely low utilization rate. Using it as a flame retardant component has good environmental protection effects and low cost.

[0093] The specific embodiments of the present application are described above. It needs to be understood that the present application is not limited to the specific embodiments described above, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be combined with each other at will without conflict.

Claims

1. A new lignin flame retardant, characterized in that: The required raw materials are prepared according to the following weight parts: First brominated epoxy resin flame retardant: 2-3 parts; Brominated polystyrene flame retardant: 2-3 parts; Second brominated epoxy resin flame retardant: 2-3 parts; Third brominated epoxy resin flame retardant: 2-3 parts; Sodium antimonate: 2-3 parts; Lignin: 10-15 parts.

2. A method for preparing a new lignin flame retardant, characterized in that: Including steps: dissolving sodium antimonate in tartaric acid to form a first solution; Evenly distributing the first solution in the lignin powder to prepare an antimony-containing lignin flame retardant synergist; The antimony-containing lignin flame retardant synergist and the brominated flame retardant are uniformly mixed to prepare a new lignin flame retardant.

3. The method for preparing the novel lignin flame retardant according to claim 2, wherein: The brominated flame retardants include brominated epoxy resin flame retardants and brominated polystyrene flame retardants.

4. The method for preparing the novel lignin flame retardant according to claim 3, characterized in that: The brominated epoxy resin flame retardant includes a first brominated epoxy resin flame retardant, a second brominated epoxy resin flame retardant, and a third brominated epoxy resin flame retardant.

5. The method for preparing the novel lignin flame retardant according to claim 4, characterized in that: The raw materials required for preparing the new lignin flame retardant are prepared according to the following weight parts: First brominated epoxy resin flame retardant: 2-3 parts; Brominated polystyrene flame retardant: 2-3 parts; Second brominated epoxy resin flame retardant: 2-3 parts; Third brominated epoxy resin flame retardant: 2-3 parts; Sodium antimonate: 2-3 parts; Lignin: 10-15 parts.

6. The method for preparing the novel lignin flame retardant according to claim 5, characterized in that: The lignin is formed by three phenylpropane units connected to each other through ether bonds and carbon-carbon bonds. The lignin has a three-dimensional network structure and contains active groups of aromatic ring structures, aliphatic and aromatic hydroxyl groups, and quinone groups.

7. The method for preparing the novel lignin flame retardant according to claim 6, characterized in that The raw materials required for preparing the new lignin flame retardant are added into a mixing bag according to weight proportions and then mixed evenly using a high-speed mixer.

8. A method for preparing modified PBT plastic, characterized in that: The following steps are involved: Add the main material PBT and toughening agent into the high-speed mixer and heat and pre-mix at high speed; The novel lignin-based flame retardant according to claims 1 to 6 is fed into a twin-screw extruder through a side feeder, and the pre-mixed main material PBT and toughening agent are simultaneously fed into the twin-screw extruder; Then the mixed material of main material PBT, toughening agent and new flame retardant based on lignin is extruded through a twin-screw extruder; The mixed material is mixed, sheared, dispersed and filtered to obtain modified PBT plastic.