A flame-retardant and antibacterial polypropylene composition, polypropylene foamed beads, a preparation method thereof, and a molded article

Abstract

The present invention relates to a flame-retardant and antibacterial polypropylene composition, polypropylene foam beads, a preparation method thereof, and a polypropylene foam bead molded body in the field of foamed polypropylene. The flame-retardant and antibacterial polypropylene composition comprises the following components in parts by weight: 100 parts of a polypropylene base resin; 0.05 to 4.0 parts of a flame-retardant and antibacterial agent; 0.03 to 0.2 parts of a nucleating agent; the polypropylene base resin is a random copolymer polypropylene; the flame-retardant and antibacterial agent is a polymer microsphere grafted with guanidine salt on the surface, and the polymer microsphere comprises a crosslinked structure composed of a structural unit A derived from maleic anhydride, a structural unit B derived from a monomer M, and a structural unit C derived from a crosslinking agent; the monomer M is selected from C4-C9 aliphatic olefins and mixtures thereof; and the guanidine salt comprises at least one guanidine salt having flame retardancy; the foam beads have both good antibacterial effect and good flame retardancy, and have a denser and more uniform cell structure.

Description

Technical Field

[0001] The present invention relates to the field of foamed polypropylene, and particularly to a flame-retardant and antibacterial polypropylene composition, polypropylene foamed beads, a preparation method thereof, and a polypropylene foamed bead molded body. Background Art

[0002] EPP foamed beads are flammable. Polypropylene is a flammable substance. When burning, it generates a large amount of heat and is accompanied by molten droplets, which are extremely likely to spread the flame. In addition, EPP beads have a cellular structure, and their own flame-retardant performance is even worse. At present, most EPP beads cannot achieve the flame-retardant function, which limits their application in fields with high requirements for flame retardancy. Currently, in the domestic market, halogen-containing organic compounds and antimony trioxide are mainly used in combination as flame retardants to produce flame-retardant PP. When plastic products containing halogen flame retardants burn, they will generate toxic, corrosive gases and a large amount of smoke, causing great harm to the environment. In recent years, halogen flame-retardant materials have been pointed out in many environmental assessment reports that they will release highly toxic carcinogenic substances such as benzofuran and dioxin during the processing, combustion, and recycling processes, seriously endangering the environment and human health. In February 2003, the European Union took the lead in announcing the ROHS directive (Restriction of Hazardous Substances in Electrical and Electronic Equipment), and Germany, the United States, Japan, China, etc. have also successively introduced relevant environmental laws and regulations.

[0003] Currently, relatively mature halogen-free flame retardants for polypropylene include hydroxides, phosphorus-based, nitrogen-based, and their combinations. Hydroxide flame retardants represented by magnesium hydroxide and aluminum hydroxide often require an addition amount of more than 60 wt% to make polypropylene reach the UL94 V0 flame-retardant grade required for insulating sheets, but this also leads to difficult processing of flame-retardant polypropylene. Phosphorus-based flame retardants represented by red phosphorus and organophosphoric esters have a lower addition amount than hydroxides, but the insulation grade of polypropylene sheets is reduced due to the high water absorption rate and exudation rate of the products. Nitrogen-based flame retardants represented by melamine and triazine cannot make the products reach a high flame-retardant grade when the thickness of the molded body or sheet is in the range of 0.125 - 0.75 mm. Therefore, it has very important practical significance to develop a low-smoke and environmentally friendly flame-retardant PP composite material. In addition, by introducing polymer microspheres, the addition amount of the flame retardant can be effectively reduced, which is beneficial to the improvement of the cellular structure of polypropylene foamed beads and the mechanical properties of the foamed molded body. Currently, environmentally friendly flame retardants refer to those with low halogen content, meeting the requirements of IEC (International Electrotechnical Commission) 61249-2-21, and are called environmentally friendly flame-retardant systems.

[0004] In recent years, with the improvement of people's living standards and the enhancement of health awareness, the demand for various antibacterial material products has been increasing continuously. Among them, antibacterial plastic products account for a large proportion. A variety of daily products, including refrigerators, air conditioners, various food containers, packaging bags, washing machines, toy products, vacuum cleaners, etc., all use various thermoplastic antibacterial plastics. There are also relatively high requirements for the antibacterial level of PP foamed products. The preparation of antibacterial plastics is mainly achieved by adding a certain amount of antibacterial agents during the plastic granulation process. There are many types of antibacterial agents, including inorganic antibacterial agents and organic antibacterial agents. Inorganic antibacterial agents include Ag, Zn-zeolite, Ag, Zn-zirconium phosphate salts, Ag, Zn-water-soluble glass, etc., and organic antibacterial agents include quaternary ammonium salts, quaternary phosphonium salts, imidazoles, pyridines, organometallic compounds, etc. Inorganic antibacterial agents and organic antibacterial agents each have their own advantages and disadvantages. Inorganic antibacterial agents have relatively high heat resistance, but there are disadvantages such as the easy discoloration of Ag-based antibacterial agents, and relatively large usage amounts and high costs; organic antibacterial agents have relatively high bactericidal efficiency and less addition amounts, but there are disadvantages such as poor heat resistance, easy precipitation, and low safety. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, such as poor flame retardancy and antibacterial performance of foamed bead formed bodies, high addition amounts of flame retardants, and damage to the cell structure, the present invention provides a flame retardant and antibacterial polypropylene composition, specifically a flame retardant and antibacterial polypropylene composition, polypropylene foamed beads, a preparation method thereof, and a formed body of polypropylene foamed beads.

[0006] One of the purposes of the present invention is to provide a flame retardant and antibacterial polypropylene composition, which may comprise the following components in parts by weight:

[0007] 100 parts of polypropylene base resin;

[0008] 0.05 - 4.0 parts of a flame retardant and antibacterial agent, preferably 0.1 - 2.8 parts, more preferably 0.5 - 2 parts;

[0009] 0.03 - 0.2 parts of a nucleating agent; preferably 0.04 - 0.1 parts;

[0010] The polypropylene base resin is random copolymer polypropylene;

[0011] In the specific implementation of the present application,

[0012] The random copolymer polypropylene has the following characteristics: the melt flow index MFR is 5 - 9 g / 10 min, and the molecular weight distribution M w / M n = 6 - 20; preferably, the random copolymer polypropylene can be selected from at least one of ethylene-propylene random copolymer polypropylene, propylene-butylene random copolymer polypropylene, and ethylene-propylene-butylene random copolymer polypropylene.

[0013] The nucleating agent is a crystallization nucleating agent, and specifically can be selected from cyclo dicarboxylates or substituted aryl heterocyclic phosphates (alpha nucleating agent); preferably selected from disodium bicyclo[2,2,2]octane-2,3-dicarboxylate and / or sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate.

[0014] The flame retardant and antibacterial agent is polymer microspheres grafted with guanidine salts on the surface. The polymer microspheres comprise a crosslinked structure composed of structural unit A derived from maleic anhydride, structural unit B derived from monomer M, and structural unit C derived from a crosslinking agent; the monomer M is selected from C4-C9 aliphatic olefins and mixtures thereof; and, the guanidine salt comprises at least one guanidine salt with flame retardancy.

[0015] As used herein, the "polymer microspheres" refer to polymer particles with a diameter ranging from nanometers to micrometers and a spherical or quasi-spherical shape.

[0016] The average particle size of the polymer microspheres grafted with guanidine salts is preferably 200-2000 nm. (Such as 200 nm, 250 nm, 350 nm, 450 nm, 550 nm, 650 nm, 750 nm, 850 nm, 950 nm, 1050 nm, 1150 nm, 1250 nm, 1350 nm, 1450 nm, 1550 nm, 1650 nm, 1750 nm, 1850 nm, 2000 nm or any value between the above values). The average particle size is characterized by the number average particle size and is measured by means of a scanning electron microscope.

[0017] The polymer microspheres are preferably monodisperse, that is, polymer microspheres with uniform particle sizes.

[0018] Preferably, the polymer microspheres used as the grafting substrate comprise a crosslinked alternating copolymer structure formed by maleic anhydride, monomer M, and a crosslinking agent. Using such microspheres can advantageously improve the grafting efficiency of guanidine salts and is beneficial to the uniform distribution of the grafted guanidine salts in the resin matrix and the final product; due to the increased content and uniform distribution of maleic anhydride monomer units, this is also beneficial to the uniform distribution and dispersion of the flame retardant and antibacterial agent microspheres in the resin matrix and the final product, and even additional compatibilizers may not be required.

[0019] As used herein, the structural unit formed after polymerizing maleic anhydride is called structural unit A, the structural unit formed after polymerizing monomer M is called structural unit B, and the structural unit formed after polymerizing the crosslinking agent (or called crosslinking monomer) is called structural unit C.

[0020] In this text, the monomer M is selected from C4-C9 aliphatic olefins and mixtures thereof, preferably C4 and / or C5-aliphatic monoolefins or diolefins or mixtures of their isomers or mixtures of monoolefins and diolefins, such as trans-2-butene, cis-2-butene, n-butene, isobutene or mixtures thereof, or isoprene, cyclopentadiene, 1,4-pentadiene, piperylene, 1-pentene, 2-pentene, cyclopentene, 2-methyl-1-butene, 2-methyl-2-butene or mixtures thereof.

[0021] As the monomer M, C4 and / or C5 fractions from the refining or ethylene industry can be used, preferably C4 and / or C5 fractions obtained from ethylene cracking in the petrochemical industry. The C4 fraction obtained from ethylene cracking may include trans-2-butene, cis-2-butene, n-butane, n-butene, isobutene and other substances. The C5 fraction obtained from ethylene cracking may include diolefins (isoprene, cyclopentadiene, 1,4-pentadiene, piperylene), monoolefins (1-pentene, 2-pentene, cyclopentene, 2-methyl-1-butene, 2-methyl-2-butene), alkanes (n-pentane, isopentane, cyclopentane, 2-methylbutane), alkynes (butyne-2, 3-penten-1-yne) and other substances. The C4 and C5 fractions as ethylene cracking products are readily available. Using such a mixed monomer to prepare polymer microspheres can help improve the added value of C4 and C5 fractions and reduce the cost of the method of the present invention.

[0022] The crosslinking degree of the polymer microspheres grafted with guanidine salts can be ≥50% (such as 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or any value between the above values), preferably ≥70%, more preferably ≥90%. The crosslinking degree of the flame retardant and antibacterial agent represents the gel content and is measured by a solvent extraction method. The polymer microspheres have a dissolution product of ≤8 wt% (such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5.5 wt%, 6.5 wt%, 7.5 wt%, 8 wt% or any value between the above values) in 5 times the weight of acetone at 50 °C for 30 min; correspondingly, the crosslinking degree is preferably ≥92%.

[0023] The flame retardant and antibacterial polymer microspheres grafted with guanidine salts have a shell crosslinked structure, and thus have better solvent resistance and thermal stability.

[0024] Preferably,

[0025] The molar ratio range of the structural unit A and the structural unit B can be (0.5:1) to (1:0.5), preferably (0.75:1) to (1:0.75).

[0026] As the crosslinking agent, also known as the crosslinking monomer, any suitable crosslinking monomer can be used, preferably a vinyl-containing monomer with difunctional or more functionality that can undergo free radical polymerization. Preferably, the crosslinking agent can be at least one of divinylbenzene and an acrylate crosslinking agent containing at least two acrylate groups; the acrylate group preferably has the structural formula: -O-C(O)-C(R')=CH2, where R' is H or an alkyl group with 1 to 4 carbon atoms (such as methyl); more preferably, the acrylate group is an acrylate group and / or a methacrylate group.

[0027] More preferably, the crosslinking agent can be selected from one or more of divinylbenzene, propylene glycol bis(meth)acrylate, ethylene glycol bis(meth)acrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane tetraacrylate, trimethylolpropane tetramethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethylene glycol phthalate diacrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ethoxylated polyfunctional acrylates, etc.; more preferably,

[0028] The propylene glycol bis(meth)acrylate can be selected from one or more of 1,3-propylene glycol dimethacrylate, 1,2-propylene glycol dimethacrylate, 1,3-propylene glycol diacrylate, 1,2-propylene glycol diacrylate, etc.; the ethylene glycol bis(meth)acrylate can be selected from one or more of ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, etc.

[0029] In this article, the expression "(meth)acrylate" includes acrylate, methacrylate, and their mixtures.

[0030] The guanidine salt can be selected from one or more of small molecule guanidine salts and guanidine salt polymers. Preferably, the guanidine salt contains at least one small molecule guanidine salt and at least one guanidine salt polymer; more preferably, both the small molecule guanidine salt and the guanidine salt polymer are guanidine salts with flame retardancy.

[0031] The small molecule guanidine salts described above may be selected from guanidine phosphate, guanidine hydrochloride, guanidine nitrate, guanidine hydrobromide, guanidine oxalate, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, and amino guanidine salts such as inorganic and organic salts of monoamino guanidine, diamino guanidine, and triamino guanidine, such as carbonates, nitrates, phosphates, oxalates, hydrochlorides, hydrobromides, and sulfonates. More preferably, the small molecule guanidine salts are selected from one or more of guanidine phosphate, guanidine hydrochloride, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, and nitrates, phosphates, hydrochlorides, hydrobromides, and sulfonates of monoamino guanidine, diamino guanidine, and triamino guanidine, etc.; the small molecule guanidine salts are even more preferably one or more of guanidine phosphate, guanidine hydrochloride, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, guanidine hydrobromide, triamino guanidine nitrate, monoamino guanidine nitrate, triamino guanidine phosphate, triamino guanidine hydrochloride, triamino guanidine hydrobromide, and triamino guanidine sulfonate.

[0032] The guanidine salt polymers described above are preferably selected from at least one of the following substances: inorganic and organic salts of polyhexamethylene (bis)guanidine, such as polyhexamethylene (bis)guanidine hydrochloride, polyhexamethylene (bis)guanidine phosphate, polyhexamethylene (bis)guanidine acetate, polyhexamethylene (bis)guanidine oxalate, polyhexamethylene (bis)guanidine stearate, polyhexamethylene (bis)guanidine laurate, polyhexamethylene (bis)guanidine benzoate, polyhexamethylene (bis)guanidine sulfonate, and other inorganic or organic salts of polyhexamethylene (bis)guanidine and one or more of polyoxyethylene guanidine salts; more preferably, the guanidine salt polymers may be selected from one or more of polyhexamethylene (bis)guanidine hydrochloride, polyhexamethylene (bis)guanidine phosphate, polyhexamethylene (bis)guanidine sulfonate, and polyhexamethylene (bis)guanidine oxalate.

[0033] The guanidine salts grafted onto the polymer microspheres according to the present invention contain at least one guanidine salt with flame retardancy, thereby realizing polymer microspheres with both antibacterial and flame retardant properties. The guanidine salt with flame retardancy contains flame retardant elements, preferably may contain phosphorus, halogen, and / or nitrogen atoms other than the nitrogen atoms of the guanidine group. Preferably, the guanidine salt with flame retardancy is selected from at least one of guanidine phosphate, guanidine hydrochloride, guanidine hydrobromide, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, and phosphates, hydrochlorides, hydrobromides, nitrates, carbonates, oxalates, sulfonates of amino guanidine, and polymers of the above guanidine salts; more preferably, at least one of guanidine phosphate, guanidine hydrochloride, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, guanidine hydrobromide, phosphates, hydrochlorides, hydrobromides, nitrates, sulfonates of amino guanidine, polyhexamethylene (bis)guanidine hydrochloride, and polyhexamethylene (bis)guanidine phosphate. Among them, the amino guanidine may be selected from at least one of monoamino guanidine, diamino guanidine, and triamino guanidine.

[0034] The above-mentioned polyhexamethylene (bis)guanidine hydrochloride refers to polyhexamethylene guanidine hydrochloride and / or polyhexamethylene bisguanidine hydrochloride, and the names of other similar substances are analogized.

[0035] The guanidine salt with flame retardancy may account for 30-100 wt% of the total weight of the guanidine salt; preferably 50-100 wt%; more preferably 80-100 wt%; for example, specifically it can be: 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 100% (by weight).

[0036] The flame retardant and antibacterial agent prepared and used in the present invention is described in the patent application No. 201911042238X, and the entire content of this patent application can be referred to here.

[0037] In some specific embodiments of the present application,

[0038] The flame retardant and antibacterial polypropylene composition preferably further comprises an aluminum hypophosphite-based flame retardant and / or a halogen-containing flame retardant. A synergistic effect is generated between the flame retardant and antibacterial microspheres of the present invention and the aluminum hypophosphite-based flame retardant and / or the halogen-containing flame retardant, and the total addition amount of the flame retardant can be significantly reduced under the condition of achieving the same flame retardant effect.

[0039] The aluminum hypophosphite-based flame retardant may be selected from inorganic aluminum hypophosphite and aluminum alkyl phosphinates (such as at least one of aluminum diethyl phosphinate, aluminum dipropyl phosphinate, aluminum phenyl phosphinate, etc.) and their combinations; preferably selected from inorganic aluminum hypophosphite and / or aluminum diethyl phosphinate. Based on 100 parts by weight of the polypropylene base resin, the addition amount of the aluminum hypophosphite-based flame retardant can be 0-2.0 parts by weight, preferably 0.1-1.2 parts by weight, more preferably 0.1-0.6 parts by weight. The halogen-containing flame retardant is preferably melamine hydrohalide, more preferably melamine hydrobromide (MHB); based on 100 parts by weight of the polypropylene base resin, the addition amount of the halogen-containing flame retardant can be 0-2.0 parts by weight, preferably 0.1-1.2 parts by weight, more preferably 0.1-0.8 parts by weight.

[0040] The flame retardant and antibacterial thermoplastic resin composition preferably further comprises a flame retardant synergist and / or a mildew-proof agent. The addition of the flame retardant synergist can further improve the flame retardancy efficiency, and the addition of the mildew-proof agent can further improve the antibacterial efficiency. Thus, under the condition of achieving the same flame retardant or antibacterial effect, the total addition amount of the flame retardant or antibacterial agent can be reduced.

[0041] The flame retardant synergist may be selected from at least one of 2,3-dimethyl-2,3-diphenylbutane (DMDPB, abbreviated as diisopropylbenzene dimer) and p-cumene polymer (poly diisopropylbenzene dimer). Based on 100 parts by weight of the polypropylene base resin, the addition amount of the flame retardant synergist can be 0-1.0 parts by weight, preferably 0.05-1 part by weight, more preferably 0.05-0.6 parts by weight.

[0042] The mildew-proof agent described above can be selected from at least one of pyrithione-based, isothiazolinone-based, 10,10'-oxybisphenoxazine (OBPA), 3-iodo-2-propynyl butylcarbamate (IPBC), 2,4,4'-trichloro-2'-hydroxydiphenyl ether (triclosan), 2-(thiazol-4-yl)benzimidazole (thiabendazole), etc., which have good mildew-proof effects. The pyrithione-based can be selected from at least one of zinc pyrithione, copper pyrithione, bispyrithione, etc. The isothiazolinone-based can be selected from at least one of 2-methyl-1-isothiazolin-3-one (MIT), 5-chloro-2-methyl-1-isothiazolin-3-one (CMIT), 2-n-octyl-4-isothiazolin-3-one (OIT), 4,5-dichloro-2-n-octyl-3-isothiazolinone (DCOIT), 1,2-benzisothiazolin-3-one (BIT), 4-methyl-1,2-benzisothiazolin-3-one (MBIT), 4-n-butyl-1,2-benzisothiazolin-3-one (BBIT), etc.

[0043] Based on the amount of the polypropylene base resin being 100 parts by weight, the amount of the mildew-proof agent can be 0 to 5.0 parts by weight, preferably 0.05 to 4.0 parts by weight, and more preferably 0.1 to 3.6 parts by weight.

[0044] In some specific embodiments of the present application,

[0045] The flame-retardant and antibacterial polypropylene composition described above may contain a slip agent;

[0046] Based on the weight of the polypropylene base resin being 100 parts by weight, the amount of the slip agent can be 0.01 to 0.25 parts by weight, preferably 0.02 to 0.2 parts by weight.

[0047] The slip agent can be selected from stearates and / or organic carboxylic acid amides. Among them, the stearates can be selected from calcium stearate, etc., and the organic carboxylic acid amides can be selected from at least one of erucic acid amide, oleic acid amide, stearic acid stearamide, N,N'-ethylene bisstearamide, preferably N,N'-ethylene bisstearamide.

[0048] In some specific embodiments, the flame-retardant and antibacterial polypropylene composition may further contain glycerol monostearate, and the molecular formula is: C 21 H 42 O4. This substance can be dispersed into polypropylene during the processing; preferably, the addition amount of the glycerol monostearate can be 0.1 to 1% of the weight parts of the flame-retardant and antibacterial agent.

[0049] In specific use, other functional additives can also be added. Taking the thermoplastic resin as 100 parts by weight, the dosage of other functional additives can be 0.1 to 100 parts by weight, and the specific dosage can be adjusted according to needs. The other functional additives may include at least one of antioxidants, light stabilizers, toughening agents, compatibilizers, pigments, dispersants, etc.

[0050] The second object of the present invention is to provide a method for preparing the flame-retardant and antibacterial polypropylene composition, which may include the following steps:

[0051] (a) Mix the components including the polypropylene base resin, the flame-retardant and antibacterial agent, and the nucleating agent to obtain a blend; commonly used stirring and mixing equipment in the art can be used;

[0052] (b) Add the blend into an extruder for extrusion and pelletizing;

[0053] Preferably, in step (b), the extrusion temperature is 180 - 230 °C.

[0054] Preferably, the method for preparing the flame-retardant and antibacterial polypropylene composition includes:

[0055] (1) Weigh the components of the flame-retardant and antibacterial polypropylene composition according to the ratio described in the first object of the present invention and put them into a high-speed mixer for mixing to obtain a blend. Preferably, the components including polypropylene, flame-retardant and antibacterial agent, flame retardant, flame-retardant synergist, nucleating agent and other additives are put into a high-speed mixer for mixing to obtain a blend.

[0056] (2) Extrude the above blend (for example, it can be added into a twin-screw extruder, and the extrusion temperature can be 180 - 230 °C), pelletize and inject mold. The flame-retardant and antibacterial polypropylene resin pellets are prepared by the above method.

[0057] The composition containing polymer microspheres and flame retardants according to the present invention helps to improve the antibacterial and flame-retardant properties of polypropylene, and at the same time, the use of conventional cell nucleating agents such as talcum powder, silica, calcium carbonate and the like can be omitted.

[0058] Among them,

[0059] The preparation method of the flame-retardant and antibacterial agent may include the following steps:

[0060] Polymer microspheres are prepared by crosslinking copolymerization reaction of components including maleic anhydride, the monomer M and the crosslinking agent in the presence of an initiator, and then the polymer microspheres are contacted with guanidine salt to graft the guanidine salt onto the polymer microspheres, thereby obtaining the flame-retardant and antibacterial agent;

[0061] The polymer microspheres are preferably prepared by a self-stabilized precipitation polymerization method. The self-stabilized precipitation polymerization is a reaction method for preparing monodisperse polymer microspheres without adding any auxiliaries such as stabilizers or dispersants. It can generate polymer microspheres in one step. The obtained polymer microspheres have uniform, regular morphology and size, controllable structure, adjustable particle size, and can use ester solvents with relatively low toxicity. The obtained polymer system has the characteristic of self-stabilization. The flame retardant and antibacterial agent obtained by using such polymer microspheres has good dispersibility in the matrix resin, and can achieve better and more uniform distribution of grafted guanidine salts, thus helping to improve the flame retardant and antibacterial effects of the flame retardant and antibacterial agent.

[0062] Specifically,

[0063] The preparation method of the flame retardant and antibacterial agent may include the following steps:

[0064] (1) In an organic solvent, in the presence of a first part of initiator, maleic anhydride and a first part of monomer M are contacted for reaction, and then a feed containing a crosslinking agent (preferably a solution containing a crosslinking agent) is introduced and the reaction is continued; during the continued reaction process, the reaction system contains maleic anhydride, monomer M and a crosslinking agent; wherein, the feed containing a crosslinking agent contains a crosslinking agent, an optional second part of monomer M, an optional second part of initiator and an optional solvent;

[0065] (2) Guanidine salt is added to the product obtained in step (1), preferably a guanidine salt solution, and the reaction is continued to graft the guanidine salt on the surface of the product obtained in step (1).

[0066] In the above step (1),

[0067] The dosage ratio of maleic anhydride to monomer M can be a conventional choice. However, in the preferred embodiment of the present invention, relative to 100 mol of the maleic anhydride, the total amount of monomer M (the total amount of the first part of monomer M and the second part of monomer M calculated as terminal olefins) can be 50 - 150 mol, more preferably 75 - 100 mol.

[0068] In the above step (1), monomer M can be fed in one step (i.e., the amount of the second part of monomer M can be zero), or can be fed in two parts (i.e., divided into the first part of monomer M and the second part of monomer M, and the amount of the second part of monomer M is greater than 0). According to the embodiment of the present invention, the molar ratio between the second part of monomer M and the first part of monomer M can be (0 - 100):100 (such as 0, 1:100, 5:100, 15:100, 25:100, 30:100, 45:100, 50:100, 60:100, 70:100, 80:100, 90:100, 100:100 or any value between the above values).

[0069] In the preparation method of the guanidine salt flame retardant and antibacterial microspheres, the amount of the organic solvent can be a conventional choice as long as it provides a suitable medium for the reaction in step (1). Preferably, relative to 100 mol of maleic anhydride, the amount of the organic solvent can be 50 - 150 L.

[0070] Preferably, the organic solvent can be a solvent commonly used in various solution polymerization reactions. For example, the organic solvent includes alkyl organic acid esters, that is, the organic solvent can be selected from alkyl organic acid esters, or a mixture of alkyl organic acid esters and alkanes, or a mixture of alkyl organic acid esters and aromatic hydrocarbons; wherein, the alkyl organic acid esters include, but are not limited to: methyl formate, ethyl formate, propyl formate, butyl formate, isobutyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, pentyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isobutyl butyrate, isoamyl butyrate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, ethyl phenylacetate, etc., at least one of them; the alkanes include, but are not limited to: n-hexane and / or n-heptane. The aromatic hydrocarbons include, but are not limited to: at least one of benzene, toluene and xylene.

[0071] and / or,

[0072] In the said step (1),

[0073] In the preparation method of the flame retardant and antibacterial agent, there is no special requirement for the amount of the initiator. Preferably, relative to 100 mol of maleic anhydride, the total amount of the initiator (the total amount of the first part of the initiator and the second part of the initiator) can be 0.05 - 10 mol, preferably 0.5 - 5 mol, more preferably 0.8 - 1.5 mol.

[0074] In the said step (1), the initiator can be fed in one step (that is, the amount of the second part of the initiator can be zero), or can be fed in two parts (that is, divided into the first part of the initiator and the second part of the initiator, and the amount of the second part of the initiator is greater than 0). According to the embodiments of the present invention, the molar ratio between the second part of the initiator and the first part of the initiator can be (0 - 100):100 (such as 0, 1:100, 5:100, 15:100, 25:100, 30:100, 45:100, 50:100, 60:100, 70:100, 80:100, 90:100, 100:100 or any value between the above values).

[0075] The initiator can be a reagent commonly used in the field for initiating the polymerization reaction of maleic anhydride and olefins, and can be a thermal decomposition initiator. Preferably, the initiator can be selected from at least one of benzoyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, and azobisisoheptonitrile.

[0076] In the preparation method of the flame retardant and antibacterial agent, there is no particular limitation on the dosage of the crosslinking agent, as long as the required degree of crosslinking can be achieved. Preferably, relative to 100 mol of maleic anhydride, the dosage of the crosslinking agent can be 1 to 40 mol, preferably 6 to 20 mol.

[0077] The type of the crosslinking agent is as described above.

[0078] The feed of the crosslinking agent can contain the crosslinking agent, optionally the remaining second part of monomer M, optionally the remaining second part of initiator, and optionally a solvent, preferably in the form of a solution containing a solvent. There is no particular requirement for the type and content of the solvent in the solution containing the crosslinking agent, as long as the solute therein is fully dissolved. Generally, the type of the solvent in the solution containing the crosslinking agent can be the same as the organic solvent in the polymerization reaction (i.e., including alkyl organic acid esters as described above), and the content of the crosslinking agent in the solution containing the crosslinking agent can be 0.2 to 3 mol / L.

[0079] and / or,

[0080] In the step (1), maleic anhydride first contacts monomer M to carry out a partial reaction, that is, maleic anhydride and monomer M do not react completely, and only partially carry out a polymerization reaction in the presence of an initiator, so that the unreacted maleic anhydride and monomer M react with the crosslinking agent subsequently. The conditions for the reaction of maleic anhydride and monomer M can be conventional conditions, as long as it is controlled that only a partial polymerization reaction occurs between maleic anhydride and monomer M. Preferably, the conditions for the reaction of maleic anhydride and the first part of monomer M include: an inert atmosphere (such as nitrogen), the temperature can be 50 to 90 °C (more preferably 60 to 70 °C), the pressure (gauge pressure or relative pressure) can be 0.3 to 1 MPa (more preferably 0.4 to 0.5 MPa), and the time can be 0.5 to 4 h (more preferably 0.5 to 2 h).

[0081] In step (1), after maleic anhydride is contacted with monomer M for a partial reaction, a feed containing a crosslinking agent (preferably a solution) is introduced to continue the reaction, which is particularly conducive to the formation of a shell crosslinked structure. The conditions for the continued reaction can be conventional conditions as long as each substrate can participate in the reaction as much as possible. Preferably, the conditions for the continued reaction can include: the temperature can be 50-90°C, the pressure can be 0.3-1 MPa, and the time can be 1-15 h. The temperature and pressure for the continued reaction can be the same as or different from the temperature and pressure for the reaction of maleic anhydride with monomer M described above. According to a more preferred embodiment of the present invention, the manner of introducing the solution containing the crosslinking agent to continue the reaction is: at 50-90°C (more preferably 60-70°C), the solution containing the crosslinking agent is added dropwise to the product obtained in step (1) within 1-3 h, and then the reaction is continued under heat preservation for 1-4 h.

[0082] In step (2),

[0083] The guanidine salt (preferably a guanidine salt solution, more preferably an aqueous solution) is added to the product (suspension) obtained in step (1), and the reaction is carried out with rapid stirring; the amount of the guanidine salt can be a conventional selection. Preferably, relative to 1000 g of maleic anhydride, the amount of the guanidine salt can be 5 g-5000 g, preferably 20 g-3000 g, more preferably 100 g-2000 g. Relative to 1000 g of maleic anhydride, the amount of the guanidine salt solution can be 500-10000 g, preferably 1000-8000 g, more preferably 1000-6000 g. The concentration of the guanidine salt solution can be 0.5-50 wt%, preferably 1-30 wt%, more preferably 1-20 wt%.

[0084] and / or,

[0085] In step (2),

[0086] The grafting reaction can be carried out under conventional conditions. For example, the conditions for the grafting reaction can include: the temperature is 0-100°C, preferably 2.5-90°C, more preferably 5-80°C, further preferably 30-80°C; the reaction time can be 0.5-10 h, preferably 0.5-8 h, more preferably 0.5-6 h; the stirring speed can be 50-1000 rpm, preferably 50-500 rpm, more preferably 100-500 rpm.

[0087] In step (2), the product (suspension) obtained in step (1) can also be subjected to post-treatment (separation, washing and drying) and then subjected to grafting reaction. The product obtained after drying is directly added to a guanidine salt solution (preferably an aqueous solution) for reaction. The washing can use conventional washing solvents, for example, at least one of n-hexane, isohexane, cyclohexane, n-heptane, n-octane, isooctane, methanol, ethanol, propanol, isopropanol, ether, isopropyl ether and methyl tert-butyl ether. The concentration of the aqueous guanidine salt solution can be 0.5-50 wt%, preferably 1-30 wt%.

[0088] The final product obtained in step (2) can be obtained as a guanidine salt flame retardant and antibacterial microsphere product grafted with guanidine salt through further separation treatment. For example, the separation treatment can be carried out in the following manner: centrifugal separation, washing with water, washing with an organic solvent (the washing solvents described above can be used, that is, at least one of n-hexane, isohexane, cyclohexane, n-heptane, n-octane, isooctane, methanol, ethanol, propanol, isopropanol, ether, isopropyl ether and methyl tert-butyl ether), centrifugal separation, drying (such as vacuum drying).

[0089] The inventors of the present invention found in the research that in step (2), the suspension obtained in step (1) can be directly subjected to grafting reaction with a guanidine salt solution (preferably an aqueous solution) without performing the step of removing the organic solvent, and the guanidine salt flame retardant and antibacterial microsphere product of the present invention can also be effectively prepared. Therefore, according to a preferred embodiment of the present invention, in step (2), the product (suspension) obtained in step (1) can be directly reacted with a guanidine salt solution (one-pot method). In this way, a mixed system containing guanidine salt flame retardant and antibacterial microspheres is obtained. The mixed system can be obtained as a guanidine salt flame retardant and antibacterial microsphere product through further separation treatment. For example, the separation treatment can be carried out in the following manner: standing for layering, the organic phase is used for recycling, and the heavy phase is centrifuged, washed with water - centrifuged, and dried (such as vacuum drying) to obtain guanidine salt flame retardant and antibacterial microspheres. This preferred method adopts a one-pot process. The post-treatment of the product only requires one liquid-liquid separation, solid-liquid separation, washing and drying, which can effectively shorten the time-consuming of a single batch, simplify the process flow, reduce the unit equipment, and effectively reduce the energy consumption; this process only requires one organic solvent as the reaction medium, and the solvent only needs to be layered and dried to be recycled, and no special water separation device is required. Layering can be achieved in the reactor, and the solvent can be recycled without distillation and purification, saving energy and reducing consumption, and effectively reducing the environmental pollution caused by the use of organic solvents.

[0090] The flame retardant and antibacterial agent (i.e., guanidine salt flame retardant and antibacterial microspheres) according to the present invention has both good flame retardant and antibacterial effects, and is an effective single-component flame retardant and antibacterial multifunctional auxiliary agent. Compared with the current method of separately adding a flame retardant and an antibacterial agent, the guanidine salt microspheres are more easily dispersed in the thermoplastic resin matrix, thereby effectively improving the flame retardant and antibacterial efficiency.

[0091] The microspheres can be prepared using C4 and C5 fractions from the oil refining or ethylene industries, especially C4 and C5 fractions obtained as ethylene cracking products in the petrochemical industry, providing a new solution for the utilization of mixed olefin resources in the petrochemical industry and helping to improve the added value of its products.

[0092] A third object of the present invention is to provide a flame-retardant and antibacterial polypropylene foamed bead, which is prepared from the flame-retardant and antibacterial polypropylene composition described above;

[0093] Preferably, the density of the polypropylene foamed beads is less than 0.9 g / cm 3 , for example, it can be 0.01 - 0.49 g / cm 3 . The polypropylene foamed beads have dense cell structure, uniform pore size, complete morphology without rupture, and relatively low density.

[0094] A fourth object of the present invention is to provide a method for preparing the flame-retardant and antibacterial polypropylene foamed beads, which may include the following steps:

[0095] Granulating and cutting the flame-retardant and antibacterial polypropylene composition to obtain polypropylene resin microparticles; and foaming the obtained polypropylene resin microparticles.

[0096] Preferably, the foaming method can be the reaction kettle impregnation foaming method.

[0097] According to the method for preparing polypropylene foamed beads described in the present invention, the granulation can be carried out in various existing ways. For example, the polypropylene composition can be extruded through one or more dies of a twin-screw or single-screw extruder into wire rods and cut to obtain polypropylene microparticles, or an underwater micro-particle pelletizing system can be used. The specific operation process is well-known to those skilled in the art.

[0098] According to a specific embodiment of the method for preparing polypropylene foamed beads described in the present invention, the granulation process includes:

[0099] (a) Adding the above polypropylene composition and optional other additives in a certain proportion to a high-speed mixer and mixing evenly;

[0100] (b) Extruding the above mixture through a twin-screw extruder, cutting it hot, and introducing it into water at a temperature below 75°C, preferably below 70°C, more preferably 55 - 65°C for micro-particle cutting, so that the length / diameter ratio of each particle is 0.5 - 2.0, preferably 0.8 - 1.3, more preferably 0.9 - 1.1, and the average weight is 0.1 - 20 mg, preferably 0.2 - 10 mg, more preferably 1 - 3 mg. The length / diameter ratio described here is the average value of 200 randomly selected polypropylene composition particles.

[0101] The steps of the granulation method can be adjusted according to the actual situation.

[0102] According to the method for preparing polypropylene foamed beads of the present invention, the foaming can also be carried out by various existing methods. For example, it can be carried out by extrusion foaming method or by reaction kettle impregnation foaming method. Preferably, it is carried out by reaction kettle impregnation foaming method. The foamed beads obtained in this way are non-crosslinked structures, so they can be recycled according to the polypropylene modified material without causing secondary pollution, meeting the requirements of circular economy.

[0103] According to the method for preparing polypropylene foamed beads of the present invention, preferably, the foaming is carried out by reaction kettle impregnation foaming method. More preferably, the reaction kettle impregnation foaming method includes the following steps:

[0104] (1) In an autoclave, mix polypropylene resin microparticles evenly with auxiliaries such as a dispersion medium, a surfactant, a dispersant, and a dispersion enhancer.

[0105] (2) First, tighten the autoclave lid, use the air exhaust method, that is, use a foaming agent to exhaust the residual air in the autoclave, then continue to feed the foaming agent into the autoclave, start heating and initially adjust the pressure until it is stable. Subsequently, stir the autoclave at a stirring speed of 50 - 150 rmp, preferably 90 - 110 rmp, and heat it uniformly to a temperature 0.1 - 5 °C lower, preferably 0.5 - 1 °C lower, than the expansion stability temperature.

[0106] (3) Adjust the pressure in the autoclave to reach the pressure required for foaming. This pressure (gauge pressure) is 1 - 10 MPa, preferably 3 - 5 MPa. Raise the temperature to the foaming temperature at an average heating rate of 0.1 °C / minute. The foaming temperature is 0.1 - 5 °C lower, preferably 0.5 - 1 °C lower, than the melting temperature of the microparticles. Under the foaming temperature and pressure conditions, continuously stir for 0.1 - 2 hours, preferably 0.25 - 0.5 hours.

[0107] (4) Open the discharge port of the autoclave to discharge the material in the autoclave into a collection tank to obtain polypropylene foamed beads. While discharging, feed carbon dioxide gas so that the pressure in the autoclave is maintained near the foaming pressure before all the particles are completely foamed and enter the collection tank.

[0108] The steps of the foaming method can be adjusted according to the actual situation.

[0109] According to the method for preparing polypropylene foamed beads of the present invention, the dispersion medium can be various existing dispersion media that can disperse polypropylene resin microparticles therein without dissolving their components. For example, it can be at least one of water, ethylene glycol, glycerol, methanol, ethanol, etc., and water is particularly preferred. Preferably, relative to 100 parts by weight of the polypropylene resin microparticles, the amount of the dispersion medium used is 1000 - 5000 parts by weight, preferably 2500 - 3500 parts by weight.

[0110] According to the method for preparing polypropylene foamed beads of the present invention, the surfactant can be various existing components that can promote the dispersion of polypropylene resin microparticles in the dispersion medium. For example, it can be at least one of stearic acid, sodium dodecylbenzenesulfonate, quaternary ammonium compounds, lecithin, amino acids, betaines, fatty acid glycerides, sorbitan fatty acids, polysorbates, etc., and sodium dodecylbenzenesulfonate is particularly preferred. Preferably, relative to 100 parts by weight of the polypropylene resin microparticles, the amount of the surfactant used is 0.001 - 10 parts by weight, preferably 0.01 - 5 parts by weight, and more preferably 0.1 - 0.5 parts by weight.

[0111] According to the method for preparing polypropylene foamed beads of the present invention, the dispersant can be an organic dispersant or an inorganic dispersant, and an inorganic dispersant is preferred. The inorganic dispersant can be at least one of natural or synthetic clay minerals (such as kaolin, mica, garnet, clay, etc.), bauxite, titanium dioxide, basic magnesium carbonate, basic zinc carbonate, calcium carbonate, silicon dioxide, zinc borate, and iron oxide, etc., and kaolin is particularly preferred. In order to effectively prevent the polypropylene resin microparticles from melting and bonding to each other during foaming, preferably, relative to 100 parts by weight of the polypropylene resin microparticles, the amount of the dispersant used is 0.01 - 20 parts by weight, preferably 0.1 - 10 parts by weight, and more preferably 0.5 - 5 parts by weight.

[0112] According to the method for preparing polypropylene foamed beads of the present invention, the purpose of adding the dispersion enhancer is to improve the dispersion efficiency of the dispersant, that is, while reducing the amount of the dispersant used, retaining its function of preventing the melting and bonding between particles. The dispersion enhancer can be various existing inorganic compounds with a solubility of 1 mg in 100 mL of water at 40 °C and providing divalent or trivalent anions or cations. Examples of the dispersion enhancer include, but are not limited to, at least one of magnesium nitride, magnesium nitrate, aluminum phosphate, magnesium sulfate, aluminum nitride, aluminum nitrate, aluminum sulfate, ferric chloride, ferric sulfate, and ferric nitrate, etc., and aluminum sulfate is preferred. In order to obtain polypropylene foamed beads with an apparent density of 100 g / L or more, preferably, relative to 100 parts by weight of the polypropylene composition particles, the amount of the dispersion enhancer used is 0.0001 - 1 part by weight, preferably 0.01 - 0.2 part by weight.

[0113] According to the method for preparing polypropylene foamed beads of the present invention, the foaming agent can be an organic physical foaming agent or an inorganic physical foaming agent. Among them, examples of the organic physical foaming agent include but are not limited to aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane, alicyclic hydrocarbons such as cyclobutane and cyclohexane, and halogenated hydrocarbons such as chlorofluoromethane, trifluoromethane, 1,2-difluoroethane, 1,2,2,2-tetrafluoroethane, methyl chloride, ethyl chloride, and dichloromethane, etc. at least one. Examples of the inorganic physical foaming agent include but are not limited to at least one of air, nitrogen, carbon dioxide, oxygen, and water. In order to ensure good stability (uniformity), low cost, and environmental friendliness of the apparent density of the obtained polypropylene foamed beads, the foaming agent is preferably carbon dioxide and / or nitrogen, and particularly preferably carbon dioxide. In addition, the dosage of the foaming agent can be determined according to the specific type of the foaming agent, the foaming temperature, and the apparent density of the polypropylene foamed beads to be produced. For example, when nitrogen is used as the foaming agent and water is used as the dispersion medium, the pressure in the closed container when the foaming device relieves pressure (i.e., the pressure in the upper space of the closed container (gauge pressure)) is controlled at 1-12 MPa; when carbon dioxide is used as the foaming agent, the above gauge pressure is controlled at 1-7 MPa. Generally speaking, the ideal pressure in the upper space of the closed container increases as the apparent density of the polypropylene composition particles to be obtained decreases.

[0114] The fifth object of the present invention is to provide an application of the flame-retardant and antibacterial polypropylene composition or the flame-retardant and antibacterial polypropylene foamed beads.

[0115] The sixth object of the present invention is to provide a flame-retardant and antibacterial polypropylene foamed bead molded body, which is obtained by molding a product prepared according to the flame-retardant and antibacterial polypropylene foamed beads and / or according to the method of the flame-retardant and antibacterial polypropylene foamed beads.

[0116] According to the present invention, the molding can be carried out in various existing molding machines, and the molding conditions can all be conventional selections in the art. Those skilled in the art can all know this and will not be elaborated here.

[0117] Through the above technical solution, the present invention provides a polypropylene composition containing a flame retardant metal salt as a cell nucleating agent, which can be further made into flame retardant and antibacterial polypropylene foamed beads. These beads have a denser and more uniform cell structure, with uniform pore sizes, complete and unbroken morphology, and a lower density. In addition, the foamed beads have a non-crosslinked structure, so they can be recycled without causing secondary pollution, meeting the requirements of circular economy. Moreover, the molded product made from the foamed beads of the present invention has higher flame retardant and antibacterial properties and a lower flame retardant addition amount. It has both good antibacterial effects and good flame retardancy, and is particularly suitable for manufacturing in crowded places such as schools, hospitals, and hotels, as well as emerging fields such as smart home appliances and new energy vehicles. Description of the Drawings

[0118] Figure 1 It is a cross-sectional photograph of the foamed beads prepared in Example 5;

[0119] Figure 2 It is a cross-sectional photograph of the foamed beads prepared in Comparative Example 5. Detailed Description of the Invention

[0120] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0121] The endpoints and any values disclosed in the ranges in this article are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0122] The present invention will be described in detail below through embodiments.

[0123] In the following embodiments and comparative examples, the relevant data was obtained according to the following test methods:

[0124] (1) Melt Index MI: It was measured according to the method specified in GB / T3682-2000, where the test temperature was 230°C and the load was 2.16 kg.

[0125] (2) Density of polypropylene and the composition: It was measured according to the method specified in GB / T1033.2-2010 and using the density gradient column method; the density of the foamed polypropylene beads was measured according to ASTM D792.

[0126] (3) Surface resistivity of the foamed bead molding: GB / T1410-2006.

[0127] (4) The cell density is tested according to the following method:

[0128] First, observe the cross-section of polypropylene foamed beads using a scanning electron microscope. Select a certain area from the obtained electron microscope photos to obtain information such as the area of this area and the number of cells. The cell density of the beads can be obtained using the following formula:

[0129]

[0130] where: n is the number of cells in the scanning electron microscope photo, M is the magnification, and A is the area of the selected area on the SEM photo (unit: cm 2 ), is the foaming ratio of the polypropylene foamed beads.

[0131] (5) Antibacterial test: It is determined according to the method specified in GB / T 31402-2015.

[0132] (6) Compressive strength test of the molded body: Cut out specimens of 50×50×25mm from the foamed bead molding. Based on the American ASTM standard D3575-08, conduct a compressive strength test, and use a compression speed of 10mm / min for the compression test to obtain the compressive strength when the molding is compressed by 50%.

[0133] (7) Horizontal burning test of the foam material: UL94, flammability test of equipment and appliance component materials.

[0134] Raw material source

[0135] All the raw materials described in this application are commercially available.

[0136] Glycerol monostearate is purchased from Croda, ATMER129V.

[0137] Random copolymer polypropylene 4908: Purchased from Sinopec Yanshan Company. The melt flow rate is 8±0.5g / 10min (230°C, 2.16kg).

[0138] Random copolymer polypropylene E680E: Purchased from Sinopec Shanghai Company. The melt flow rate is 6.8±0.5g / 10min (230°C, 2.16kg).

[0139] Random copolymer polypropylene 5608: Purchased from Sinopec Yanshan Company. The melt flow rate is 8±0.5g / 10min (230°C, 2.16kg).

[0140] Preparation of Flame Retardant and Antibacterial Agent

[0141] XQ101:

[0142] (1) The composition of the mixed butene gas is as follows: trans-2-butene, 40.83 wt%; cis-2-butene, 18.18 wt%; n-butane, 24.29 wt%; 1-butene, 9.52 wt%; isobutene, 2.78 wt%; others, 4.4 wt%. In an autoclave, 100 g of maleic anhydride and 2 g of azobisisobutyronitrile are dissolved in 800 mL of isoamyl acetate to form Solution 1. The measured mixed butene is introduced (the molar ratio of maleic anhydride to the effective component (terminal olefin) in the mixed olefin is 1:1). Under a nitrogen atmosphere, the reaction is carried out at 70 °C and 0.5 MPa for 1 hour;

[0143] (2) 25 g of divinylbenzene is dissolved in 200 mL of isoamyl acetate to form Solution 2. Solution 2 is added to the reaction system by a piston pump and added dropwise for 2 hours. After the addition is completed, the reaction system continues to be kept warm and react for 3 hours.

[0144] (3) After the reaction, the pressure is released, and 200 g of each of the aqueous solutions of guanidine dihydrogen phosphate (15 wt%) and polyhexamethylene biguanide hydrochloride (15 wt%) are added, and the reaction is carried out at 80 °C for 3 hours. The reaction system is allowed to stand and separate into layers. The heavy phase is centrifuged at 5000 rad / min for 20 minutes by a centrifuge. The obtained solid is stirred and washed with 4 L of water, centrifuged at 5000 rad / min for 20 minutes by a centrifuge, the obtained solid is again stirred and washed with 4 L of water, centrifuged at 5000 rad / min for 20 minutes by a centrifuge, and the obtained solid is dried in vacuo to obtain the flame retardant and antibacterial agent, namely polymer microspheres 1# grafted with guanidine salt on the surface. The average particle size of the obtained polymer microspheres is 1280 nm. The weight percentage of the eluate of the obtained polymer microspheres in 5 times the weight of acetone at 50 °C for 30 min is 5.5%.

[0145] XQ102:

[0146] Prepare the flame retardant and antibacterial agent according to the method of Example 1, except that the system after the reaction in step (2) is centrifuged at 5000 rad / min for 30 minutes by a centrifuge to obtain crosslinked mixed butene / maleic anhydride polymer microspheres, which are washed and purified with n-hexane and dried in vacuum. Then, the dried crosslinked mixed butene / maleic anhydride polymer microspheres are added to 400 g of an aqueous solution mixture of guanidine dihydrogen phosphate (20 wt%) and polyhexamethylene biguanide hydrochloride (20 wt%), and reacted at 80 °C for 3 hours. The reaction system is centrifuged at 5000 rad / min for 20 minutes by a centrifuge, the obtained solid is stirred and washed with 4 L of water, centrifuged at 5000 rad / min for 20 minutes by a centrifuge, the obtained solid is stirred and washed with 4 L of water again, centrifuged at 5000 rad / min for 20 minutes by a centrifuge, and the obtained solid is dried in vacuum to obtain the flame retardant and antibacterial agent, namely polymer microspheres 2# grafted with guanidine salt on the surface. The average particle size of the obtained polymer microspheres is 1310 nm. The weight percentage of the dissolution product of the obtained polymer microspheres in 5 times the weight of acetone at 50 °C for 30 min is 5.6%.

[0147] XQ103:

[0148] (1) Dissolve 100 g of maleic anhydride and 2 g of azobisisobutyronitrile in 800 mL of isopentyl acetate in an autoclave to form Solution 1, introduce the measured mixed butene (the composition is the same as that in Example 1, and the molar ratio of maleic anhydride to the effective component (terminal olefin) in the mixed olefin is 1:1), and react at 70 °C and 0.4 MPa for 2 hours under a nitrogen atmosphere;

[0149] (2) Dissolve 15 g of divinylbenzene in 200 mL of isopentyl acetate to form Solution 2, add Solution 2 to the reaction system by a piston pump, dropwise add for 2 hours, and after the dropwise addition, the reaction system continues to be kept warm and react for 3 hours.

[0150] (3) After the reaction, release the pressure of the autoclave, add 200 g of an aqueous solution of guanidine hydrobromide (20 wt%) and 200 g of an aqueous solution of polyhexamethylene guanidine phosphate (20 wt%) respectively, and react at 60 °C for 7 hours. The reaction system is allowed to stand and separate into layers, the heavy phase is centrifuged at 5000 rad / min for 20 minutes by a centrifuge, the obtained solid is stirred and washed with 4 L of water, centrifuged at 5000 rad / min for 20 minutes by a centrifuge, the obtained solid is stirred and washed with 4 L of water again, centrifuged at 5000 rad / min for 20 minutes by a centrifuge, and the obtained solid is dried in vacuum to obtain the flame retardant and antibacterial agent, namely polymer microspheres 3# grafted with guanidine salt on the surface. The average particle size of the obtained polymer microspheres is 1210 nm. The weight percentage of the dissolution product of the obtained polymer microspheres in 5 times the weight of acetone at 50 °C for 30 min is 6.5%.

[0151] XQ104:

[0152] (1) Dissolve 100 g of maleic anhydride and 1.5 g of azobisisobutyronitrile in 800 mL of isopentyl acetate in an autoclave to form Solution 1. Introduce the measured mixed butene (with the same composition as in Example 1, and the molar ratio of maleic anhydride to the effective component (terminal olefin) in the mixed olefins is 1:0.75). Under a nitrogen atmosphere, react at 70 °C and 0.5 MPa for 1 hour;

[0153] (2) Dissolve 0.5 g of azobisisobutyronitrile and 18 g of divinylbenzene in 200 mL of isopentyl acetate to form Solution 2. Add Solution 2 to the reaction system by a plunger pump and dropwise add it for 2 hours. After the dropwise addition is completed, the reaction system continues to be kept warm and react for 3 hours.

[0154] (3) After the reaction, release the pressure of the autoclave, and add 200 g of an aqueous solution of guanidine dihydrogen phosphate (20 wt%), 200 g of an aqueous solution of guanidine hydrobromide (20 wt%), and 200 g of an aqueous solution of polyhexamethylene guanidine phosphate (20 wt%) respectively, and react at 60 °C for 10 hours. Let the reaction system stand and separate into layers. The heavy phase is centrifuged at 5000 rad / min for 20 minutes by a centrifuge. Add 4 L of water to the obtained solid, stir and wash it, then centrifuge it at 5000 rad / min for 20 minutes by a centrifuge. Again, add 4 L of water to the obtained solid, stir and wash it, and centrifuge it at 5000 rad / min for 20 minutes by a centrifuge. Vacuum dry the obtained solid to obtain the flame retardant and antibacterial agent, that is, the polymer microspheres 4# grafted with guanidine salt on the surface. The average particle size of the obtained polymer microspheres is 1510 nm. The weight percentage of the dissolution product of the obtained polymer microspheres in 5 times the weight of acetone at 50 °C for 30 minutes is 5.8%.

[0155] Examples 1-9 and Comparative Examples 1-4

[0156] Take the flame retardant and antibacterial agent, flame retardant, flame retardant synergist, mildew preventive, nucleating agent, antioxidant (hindered phenol antioxidant 1010: phosphite antioxidant 168 = 1:1 (weight ratio), and the dosage of the antioxidant is 0.1 part by weight (relative to 100 parts by weight of the basic resin)), glycerol monostearate (Croda, ATMER 129V; its dosage is five-thousandths of the weight of the used flame retardant and antibacterial agent), and mix them according to the ratio in Table 1, and use a dry powder machine to stir to obtain a uniformly mixed powder; add the above mixed powder and polypropylene to a high-speed mixer according to the ratio in Table 1; put the mixed material into a twin-screw extruder, extrude and pelletize at 195 - 210 °C, and dry to obtain flame retardant and antibacterial polypropylene resin pellets. Put some of the obtained pellets into an injection molding machine to inject and obtain a heat distortion spline, and the performance test is shown in Table 2.

[0157] Put 100 parts by weight of flame-retardant and antibacterial polypropylene resin pellets (containing polymer microspheres and flame retardants) into a high-speed mixer and mix at high speed for 30 seconds. Then add it to the LabLine100 microparticle preparation system, control the torque at about 65%, the rotation speed at 300 rpm, and perform underwater pelletizing to obtain polypropylene resin microparticles. The average length / diameter ratio of the microparticles is 0.9.

[0158] First, in an autoclave, add 100 parts by weight of polypropylene resin microparticles, 3000 parts by weight of a dispersion medium (deionized water), 0.3 parts by weight of a surfactant (sodium dodecylbenzenesulfonate), 3 parts by weight of a dispersant (kaolin), and 0.2 parts by weight of a dispersion enhancer (aluminum sulfate) into the autoclave all at once and mix them. Second, tightly close the autoclave lid, use an inert foaming agent (CO2 or nitrogen, see Table 2) to discharge the residual air in the reaction kettle through the exhaust valve and pipeline to remove the air in the reaction kettle. Feed the inert foaming agent into the autoclave and initially adjust the pressure until it stabilizes. Subsequently, stir the dispersion in the autoclave and heat it at a uniform speed to a temperature 0.5 - 1 °C lower than the expansion temperature. Then, adjust the pressure in the autoclave to reach the pressure required for foaming; increase the temperature to the foaming temperature at an average heating rate of 0.1 °C / minute. The foaming temperature is 0.5 - 1 °C lower than the melting temperature of the microparticles. Under the conditions of foaming temperature and pressure, continuously stir for 0.25 - 0.5 hours. Finally, open the discharge port of the autoclave to discharge the materials in the reaction kettle into a collection tank to obtain polypropylene foamed beads; feed carbon dioxide gas while discharging to keep the pressure in the autoclave near the foaming pressure before all the particles are completely foamed and enter the collection tank. The density of the obtained foamed beads is measured according to ASTM D792, and the specific data are shown in Table 2.

[0159] Table 1 Formulation of antibacterial and flame-retardant PP composition (the amounts in the table are all in parts by weight)

[0160]

[0161]

[0162] Table 2

[0163]

[0164]

[0165] As can be seen from Table 2, the foamed beads prepared in Examples 1 - 9 have good antibacterial and flame-retardant properties while having good mechanical properties.

[0166] As can be seen from the comparison between Example 1 and Comparative Example 3, the antibacterial and flame retardant properties of the foamed molded article of the polypropylene composition using polyhexamethylene biguanide hydrochloride as the antibacterial agent are poor. At the same addition amount, the compression properties, antibacterial and flame retardant properties of the polypropylene foamed bead molded article of the present invention are better. It was found from the comparison between Example 5 and Comparative Example 4 that the compression strength increased to a certain extent after adding the nucleating agent.

[0167] It can be seen from the cross-sectional photos of the foamed beads of Example 5 and Comparative Example 4 (see Figure 1 , Figure 2 ), that after adding the nucleating agent, the obtained foamed beads have more uniform cell structure and better cell morphology.

[0168] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A flame-retardant and antibacterial polypropylene composition, comprising the following components in parts by weight: 100 parts of polypropylene base resin; 0.05 - 4.0 parts of flame-retardant antibacterial agent; 0.03 - 0.2 parts of nucleating agent; The polypropylene base resin is random copolymer polypropylene; the random copolymer polypropylene is selected from at least one of ethylene-propylene random copolymer polypropylene, propylene-butylene random copolymer polypropylene, and ethylene-propylene-butylene random copolymer polypropylene; The flame-retardant antibacterial agent is polymer microspheres grafted with guanidine salt on the surface, and the polymer microspheres comprise a crosslinked structure composed of structural unit A derived from maleic anhydride, structural unit B derived from monomer M, and structural unit C derived from a crosslinking agent; The monomer M is an aliphatic monoolefin or diolefin of C4 and / or C5 or a mixture of its isomers or a mixture of monoolefin and diolefin; and The flame-retardant guanidine salt accounts for 30 - 100 wt% of the total weight of the guanidine salt; The guanidine salt comprises at least one small molecule guanidine salt and at least one guanidine salt polymer; both the small molecule guanidine salt and the guanidine salt polymer are flame-retardant guanidine salts; The average particle size of the polymer microspheres grafted with guanidine salt on the surface is 200 - 2000 nm; The polymer microspheres as the grafting substrate comprise a crosslinked alternating copolymer structure formed by maleic anhydride, monomer M, and a crosslinking agent.

2. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: Based on 100 parts by weight of the polypropylene base resin, the amount of the flame-retardant antibacterial agent is 0.1 - 2.8 parts by weight.

3. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: Based on 100 parts by weight of the polypropylene base resin, the amount of the nucleating agent is 0.04 - 0.1 parts by weight.

4. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: The melt flow rate MFR of the random copolymer polypropylene is 5 - 9 g / 10 min.

5. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: The nucleating agent is selected from cyclo-dicarboxylates or substituted aryl heterocyclic phosphates.

6. The flame-retardant and antibacterial polypropylene composition according to claim 5, wherein: The nucleating agent is selected from disodium bicyclo[2,2,2]octane-2,3-dicarboxylate and / or sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate.

7. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: The polymer microspheres grafted with guanidine salt on the surface have a dissolution product ≤ 8 wt% in 5 times the weight of acetone under the conditions of 50 °C and 30 min; and / or, The crosslinking degree of the polymer microspheres grafted with guanidine salt on the surface ≥ 50%, measured by the solvent extraction method.

8. The flame-retardant and antibacterial polypropylene composition according to claim 7, wherein: The crosslinking degree of the polymer microspheres grafted with guanidine salt on the surface ≥ 70%.

9. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: The monomer M is a C4 and / or C5 fraction.

10. The flame-retardant and antibacterial polypropylene composition according to claim 9, wherein: The monomer M is a C4 and / or C5 fraction obtained from an ethylene cracking process.

11. The flame-retardant and antibacterial polypropylene composition according to claim 1, characterized in that: The molar ratio range of the structural unit A and the structural unit B is (0.5:1) to (1:0.5).

12. The flame-retardant and antibacterial polypropylene composition according to claim 11, characterized in that: The molar ratio range of the structural unit A and the structural unit B is (0.75:1) to (1:0.75).

13. The flame-retardant and antibacterial polypropylene composition according to claim 1, characterized in that: The crosslinking agent is selected from vinyl-containing monomers with bifunctional or more functionalities that can undergo free radical polymerization.

14. The flame-retardant and antibacterial polypropylene composition according to claim 13, characterized in that: The crosslinking agent is selected from at least one of divinylbenzene and acrylate crosslinking agents containing at least two acrylate groups.

15. The flame-retardant and antibacterial polypropylene composition according to claim 14, characterized in that: The structural formula of the acrylate group is: -O-C(O)-C(R')=CH2, where R' is H or an alkyl group with 1 to 4 carbon atoms.

16. The flame-retardant and antibacterial polypropylene composition according to claim 15, characterized in that: The acrylate group is an acrylate group and / or a methacrylate group.

17. The flame-retardant and antibacterial polypropylene composition according to claim 14, characterized in that: The crosslinking agent is selected from one or more of divinylbenzene, bis(meth)acrylates of propylene glycol, bis(meth)acrylates of ethylene glycol, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, bis-trimethylolpropane tetraacrylate, bis-trimethylolpropane tetramethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethylene glycol diacrylate phthalate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ethoxylated polyfunctional acrylates.

18. The flame-retardant and antibacterial polypropylene composition according to claim 17, characterized in that: The bis(meth)acrylates of propylene glycol are selected from one or more of 1,3-propylene glycol dimethacrylate, 1,2-propylene glycol dimethacrylate, 1,3-propylene glycol diacrylate, and 1,2-propylene glycol diacrylate; the bis(meth)acrylates of ethylene glycol are selected from one or more of ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, and tetraethylene glycol diacrylate.

19. The flame-retardant and antibacterial polypropylene composition according to claim 1, characterized in that: The small molecule guanidine salts are selected from one or more of guanidine phosphate, guanidine hydrochloride, guanidine nitrate, guanidine hydrobromide, guanidine oxalate, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, and inorganic and organic salts of amino guanidine salts.

20. The flame-retardant and antibacterial polypropylene composition according to claim 19, wherein: The amino guanidine salts are selected from at least one of monoamino guanidine, diamino guanidine, and triamino guanidine; the inorganic acid salts are selected from at least one of the following substances: carbonate, nitrate, phosphate, hydrochloride; the organic acid salts are selected from at least one of oxalate, hydrobromide, and sulfonate.

21. The flame-retardant and antibacterial polypropylene composition according to claim 19, wherein: The small molecule guanidine salts are selected from one or more of guanidine phosphate, guanidine hydrochloride, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, and the nitrates, phosphates, hydrochlorides, hydrobromides, and sulfonates of monoamino guanidine, diamino guanidine, and triamino guanidine.

22. The flame-retardant and antibacterial polypropylene composition according to claim 19, wherein: The small molecule guanidine salts are selected from one or more of guanidine phosphate, guanidine hydrochloride, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, guanidine hydrobromide, triamino guanidine nitrate, monoamino guanidine nitrate, triamino guanidine phosphate, triamino guanidine hydrochloride, triamino guanidine hydrobromide, and triamino guanidine sulfonate.

23. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: The guanidine salt polymers are selected from at least one of the following substances: inorganic acid salts and organic acid salts of polyhexamethylene (bis) guanidine.

24. The flame-retardant and antibacterial polypropylene composition according to claim 23, wherein: The guanidine salt polymers are selected from at least one of the following substances: polyhexamethylene (bis) guanidine hydrochloride, polyhexamethylene (bis) guanidine phosphate, polyhexamethylene (bis) guanidine acetate, polyhexamethylene (bis) guanidine oxalate, polyhexamethylene (bis) guanidine stearate, polyhexamethylene (bis) guanidine laurate, polyhexamethylene (bis) guanidine benzoate, polyhexamethylene (bis) guanidine sulfonate, and polyoxyethylene guanidine salt.

25. The flame-retardant and antibacterial polypropylene composition according to claim 24, wherein: The guanidine salt polymers are selected from one or more of polyhexamethylene (bis) guanidine hydrochloride, polyhexamethylene (bis) guanidine phosphate, polyhexamethylene (bis) guanidine sulfonate, and polyhexamethylene (bis) guanidine oxalate.

26. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: The guanidine salt with flame retardancy contains flame-retardant elements.

27. The flame-retardant and antibacterial polypropylene composition according to claim 26, wherein: The guanidine salt with flame retardancy contains phosphorus atoms, halogen atoms, and / or nitrogen atoms other than the nitrogen atoms in the guanidine group.

28. The flame-retardant and antibacterial polypropylene composition according to claim 27, wherein: The guanidine salt with flame retardancy is selected from at least one of guanidine phosphate, guanidine hydrochloride, guanidine hydrobromide, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, and the phosphates, hydrochlorides, hydrobromides, nitrates, carbonates, oxalates, sulfonates of amino guanidine, and the polymers of the above guanidine salts.

29. The flame-retardant and antibacterial polypropylene composition according to claim 28, wherein: The guanidine salts with flame retardancy are selected from at least one of guanidine phosphate, guanidine hydrochloride, guanidine dihydrogen phosphate, guanidine hydrogen phosphate, guanidine hydrobromide, phosphate, hydrochloride, hydrobromide, nitrate, sulfonate of amino guanidine, polyhexamethylene (bis) guanidine hydrochloride, and polyhexamethylene (bis) guanidine phosphate.

30. The flame-retardant and antibacterial polypropylene composition according to claim 28, wherein: The amino guanidine is selected from at least one of monoamino guanidine, diamino guanidine, and triamino guanidine.

31. The flame-retardant and antibacterial polypropylene composition according to claim 1, wherein: The guanidine salts with flame retardancy account for 50 - 100 wt% of the total weight of the guanidine salts.

32. The flame-retardant and antibacterial polypropylene composition according to claim 31, wherein: The guanidine salts with flame retardancy account for 80 - 100 wt% of the total weight of the guanidine salts.

33. The flame-retardant and antibacterial polypropylene composition according to any one of claims 1 to 32, characterized in that It contains aluminum hypophosphite-based flame retardants and / or halogen-containing flame retardants.

34. The flame-retardant and antibacterial polypropylene composition according to claim 33, wherein: The aluminum hypophosphite-based flame retardants are selected from at least one of inorganic aluminum hypophosphite, alkyl aluminum phosphinate, and phenyl aluminum phosphinate.

35. The flame-retardant and antibacterial polypropylene composition according to claim 34, wherein: The alkyl aluminum phosphinate is selected from at least one of aluminum diethyl phosphinate and aluminum dipropyl phosphinate.

36. The flame-retardant and antibacterial polypropylene composition according to claim 33, wherein: The aluminum hypophosphite-based flame retardants are selected from at least one of inorganic aluminum hypophosphite and aluminum diethyl phosphinate.

37. The flame-retardant and antibacterial polypropylene composition according to claim 33, wherein: Based on 100 parts by weight of the polypropylene base resin, the dosage of the aluminum hypophosphite-based flame retardant is 0 - 2.0 parts by weight.

38. The flame-retardant and antibacterial polypropylene composition according to claim 33, wherein: Based on 100 parts by weight of the polypropylene base resin, the dosage of the aluminum hypophosphite-based flame retardant is 0.1 - 1.2 parts by weight.

39. The flame-retardant and antibacterial polypropylene composition according to claim 33, wherein: The halogen-containing flame retardant is melamine hydrohalide.

40. The flame-retardant and antibacterial polypropylene composition according to claim 39, wherein: The halogen-containing flame retardant is melamine hydrobromide.

41. The flame-retardant and antibacterial polypropylene composition according to claim 33, wherein: Based on 100 parts by weight of the polypropylene base resin, the dosage of the halogen-containing flame retardant is 0 - 2.0 parts by weight.

42. The flame-retardant and antibacterial polypropylene composition according to claim 41, wherein: Based on 100 parts by weight of the polypropylene base resin, the dosage of the halogen-containing flame retardant is 0.1 - 1.2 parts by weight.

43. The flame-retardant and antibacterial polypropylene composition according to any one of claims 1 to 32, characterized in that It contains a flame retardant synergist; Based on 100 parts by weight of the polypropylene base resin, the dosage of the flame retardant synergist is 0 - 1.0 part by weight.

44. The flame-retardant and antibacterial polypropylene composition according to claim 43, wherein: Based on 100 parts by weight of the polypropylene base resin, the dosage of the flame retardant synergist is 0.05 - 1 part by weight.

45. The flame-retardant and antibacterial polypropylene composition according to claim 43, wherein: The flame-retardant synergist is selected from at least one of 2,3-dimethyl-2,3-diphenylbutane (DMDPB) and cumene polymer (polydiisopropylbenzene).

46. The flame-retardant and antibacterial polypropylene composition according to any one of claims 1 to 32, characterized in that It contains a slip agent; Based on 100 parts by weight of the polypropylene base resin, The dosage of the slip agent is 0.01-0.25 parts by weight; The slip agent is selected from stearates and / or organic carboxylic acid amides.

47. The flame-retardant and antibacterial polypropylene composition according to claim 46, wherein: Based on 100 parts by weight of the polypropylene base resin, The dosage of the slip agent is 0.02-0.2 parts by weight.

48. The flame-retardant and antibacterial polypropylene composition according to claim 46, wherein: The stearate is selected from calcium stearate, and the organic carboxylic acid amide is selected from at least one of erucamide, oleamide, stearyl stearamide, and N,N'-ethylenebisstearamide.

49. The flame-retardant and antibacterial polypropylene composition according to claim 48, wherein: The stearate is selected from N,N'-ethylenebisstearamide.

50. The flame-retardant and antibacterial polypropylene composition according to any one of claims 1 to 32, characterized in that It contains a mildew-proof agent; The mildew-proof agent is selected from at least one of pyrithiones, isothiazolinones, 10,10'-oxybisphenoxazine (OBPA), 3-iodo-2-propynyl butylcarbamate (IPBC), 2,4,4'-trichloro-2'-hydroxydiphenyl ether (triclosan), and 2-(thiazol-4-yl)benzimidazole (thiabendazole).

51. The flame-retardant and antibacterial polypropylene composition according to claim 50, wherein: The pyrithiones are selected from at least one of zinc pyrithione, copper pyrithione, and bispyrithione; the isothiazolinones are selected from at least one of 2-methyl-1-isothiazolin-3-one (MIT), 5-chloro-2-methyl-1-isothiazolin-3-one (CMIT), 2-n-octyl-4-isothiazolin-3-one (OIT), 4,5-dichloro-2-n-octyl-3-isothiazolinone (DCOIT), 1,2-benzisothiazolin-3-one (BIT), 4-methyl-1,2-benzisothiazolin-3-one (MBIT), and 4-n-butyl-1,2-benzisothiazolin-3-one (BBIT).

52. The flame-retardant and antibacterial polypropylene composition according to claim 50, wherein: Based on 100 parts by weight of the polypropylene base resin, the dosage of the mildew-proof agent is 0-5.0 parts by weight.

53. The flame-retardant and antibacterial polypropylene composition according to claim 52, wherein: Based on 100 parts by weight of the polypropylene base resin, the dosage of the mildew-proof agent is 0.05-4.0 parts by weight.

54. The preparation method of the flame-retardant and antibacterial polypropylene composition according to any one of claims 1 to 53, characterized in that It includes the following steps: (a) Mixing the components including the polypropylene base resin, the flame-retardant and antibacterial agent, and the nucleating agent to obtain a blend; (b) Extruding and pelletizing the blend.

55. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 54, wherein: In step (b), the extrusion temperature is 180~230 °C.

56. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 54, characterized in that: The preparation method of the flame-retardant and antibacterial agent comprises the following steps: In the presence of an initiator, polymer microspheres are obtained by crosslinking copolymerization of components including maleic anhydride, the monomer M, and the crosslinking agent, and then the polymer microspheres are contacted with a guanidine salt to graft the guanidine salt onto the polymer microspheres, thereby obtaining the flame-retardant and antibacterial agent.

57. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 56, characterized in that: The polymer microspheres serving as the grafting substrate are prepared by a self-stabilizing precipitation polymerization method.

58. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 56, characterized in that: The preparation method of the flame-retardant and antibacterial agent comprises the following steps: (1) In an organic solvent, in the presence of a first part of the initiator, maleic anhydride and a first part of the monomer M are contacted for reaction, and then a feed containing a crosslinking agent is introduced to continue the reaction; wherein, the feed containing the crosslinking agent contains a crosslinking agent, an optional second part of the monomer M, an optional second part of the initiator, and an optional solvent; (2) A guanidine salt is added to the product obtained in step (1), and the reaction is continued to graft the guanidine salt onto the surface of the product obtained in step (1).

59. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 58, characterized in that: In the said step (1), Relative to 100 mol of the maleic anhydride, the total amount of the first part of the monomer M and the second part of the monomer M in terms of terminal olefins is 50~150 mol; In the said step (1), The molar ratio between the second part of the monomer M and the first part of the monomer M is (0~100):100; And / or, Relative to 100 mol of maleic anhydride, the amount of the crosslinking agent used is 1~40 mol.

60. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 59, characterized in that: In the said step (1), Relative to 100 mol of the maleic anhydride, the total amount of the first part of the monomer M and the second part of the monomer M in terms of terminal olefins is 75~100 mol.

61. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 56, characterized in that: Relative to 100 mol of maleic anhydride, the amount of the crosslinking agent used is 6~20 mol.

62. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 58, characterized in that: In the said step (1), Relative to 100 mol of maleic anhydride, the total amount of the first part of the initiator and the second part of the initiator used is 0.05~10 mol; and / or, The molar ratio between the second part of the initiator and the first part of the initiator can be (0~100):100; And / or, The initiator is selected from at least one of benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, and azobisisoheptonitrile.

63. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 62, characterized in that: In the step (1), Relative to 100 mol of maleic anhydride, the total amount of the first part of the initiator and the second part of the initiator is 0.5 to 5 mol.

64. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 58, characterized in that: In the step (1), The organic solvent is selected from alkyl organic acid esters, or a mixture of alkyl organic acid esters and alkanes, or a mixture of alkyl organic acid esters and aromatic hydrocarbons.

65. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 64, characterized in that: The alkyl organic acid esters are selected from at least one of methyl formate, ethyl formate, propyl methyl ester, butyl methyl ester, isobutyl methyl ester, amyl methyl ester, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isobutyl butyrate, isoamyl butyrate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, and ethyl phenylacetate; the alkanes are selected from n-hexane and / or n-heptane; the aromatic hydrocarbons are selected from at least one of benzene, toluene, and xylene.

66. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 64, characterized in that: Relative to 100 mol of maleic anhydride, the amount of the organic solvent used can be 50 to 150 L.

67. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 58, characterized in that: In the step (1), The conditions for the reaction of maleic anhydride with the first part of monomer M include: an inert atmosphere, a temperature of 50 to 90 °C, a pressure of 0.3 to 1 MPa, and a time of 0.5 to 4 h; and / or, The conditions for the subsequent reaction include: a temperature of 50 to 90 °C, a pressure of 0.3 to 1 MPa, and a time of 1 to 15 h.

68. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 58, characterized in that: In the step (2), Relative to 1000 g of maleic anhydride, the amount of the guanidine salt used is 5 g to 5000 g; and / or, In the step (2), The conditions for the grafting reaction include: a temperature of 0 to 100 °C.

69. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 68, characterized in that: In the step (2), Relative to 1000 g of maleic anhydride, the amount of the guanidine salt used is 20 g to 3000 g; The guanidine salt is added in the form of a solution.

70. The preparation method of the flame-retardant and antibacterial polypropylene composition according to claim 68, wherein: In the step (2), the guanidine salt is added in the form of an aqueous solution; and / or, In the step (2), the conditions of the graft reaction include: the temperature is 2.5 to 90 °C.

71. A flame-retardant and antibacterial polypropylene foamed bead, which is prepared from the flame-retardant and antibacterial polypropylene composition according to any one of claims 1 to 53 or from the polypropylene composition prepared by the method according to any one of claims 54 to 70.

72. The flame-retardant and antibacterial polypropylene foamed bead according to claim 71, wherein: The density of the polypropylene foam beads is less than 0.9 g / cm 3 .

73. The flame-retardant and antibacterial polypropylene foamed bead according to claim 72, wherein: The density of the polypropylene foamed beads is 0.01~0.49 g / cm 3 .

74. The preparation method of the flame-retardant and antibacterial polypropylene foamed bead according to any one of claims 71 to 73, comprising the following steps: Granulating and cutting the flame-retardant and antibacterial polypropylene composition to obtain polypropylene resin microparticles; Foaming the obtained polypropylene resin microparticles.

75. The preparation method of the flame-retardant and antibacterial polypropylene foamed bead according to claim 74, wherein: The foaming method is the reaction kettle impregnation foaming method.

76. The application of the flame-retardant and antibacterial polypropylene composition according to any one of claims 1 to 53 or the flame-retardant and antibacterial polypropylene foamed bead according to any one of claims 71 to 73.

77. A flame-retardant and antibacterial polypropylene foamed bead molded body, which is obtained by molding the flame-retardant and antibacterial polypropylene foamed bead according to any one of claims 71 to 73 or the flame-retardant and antibacterial polypropylene foamed bead prepared by the method according to claim 74 or 75.

Images