CN105693972A - Preparation method of antibacterial modification type soft polyurethane foam - Google Patents

Abstract

A preparation method of antibacterial modified polyurethane flexible foam, which is prepared by the following weight percent by prepolymer method, semi-prepolymer method or one-step method: polyisocyanate 25% to 40%; polyether polyol 50% 70%; antibacterial agent 0.01-5%; other additives 2-10%; other additives include catalysts, foaming agents, surfactants or cross-linking agents. The invention realizes the one-step completion of antibacterial modification and polyurethane synthesis, and the antibacterial modification is carried out in a chemical bonding manner, and the prepared antibacterial modified polyurethane soft foam has long-term antibacterial properties, fast sterilization rate, wide antibacterial range, and storage stability high.

Description

Preparation method of antibacterial modified polyurethane flexible foam

technical field

The invention relates to a polyurethane material, in particular to a preparation method of an antibacterial modified polyurethane flexible foam.

Background technique

Polyurethane material is a kind of multi-purpose synthetic resin with various product forms. It has rich varieties of raw materials, many formula combinations, and a wide range of product forms and application fields. The main product forms include soft and rigid foam plastics, elastomers, coatings, adhesives Agents, synthetic leather, waterproof materials and paving materials, etc.

Among polyurethane products, the product form with the largest output and usage is polyurethane flexible foam, which is a porous polyurethane material composed of a large number of microscopic pores and polyurethane resin pore walls. Low density, good elastic recovery, sound absorption, breathability, heat preservation and other properties, widely used in furniture cushions, vehicle seat cushions and various soft laminated composite cushions. In industry and civil use, soft foam is used as filter material, sound insulation material, shockproof material, decoration material, packaging material and heat insulation material.

During the preservation and use of polyurethane flexible foam, the growth and reproduction of microorganisms will cause certain damage to it. It is well known that microorganisms such as algae, bacteria, molds (fungi and yeast) and viruses can inhabit and survive on the surface of objects, especially when there are residual nutrients in dead corners, rough surfaces or micro crevices. The growth of microorganisms on polymer surfaces can not only cause discoloration, stains, odors, biodegradation and ultimately reduce mechanical strength, shorten product life, but more seriously, it can bring great harm to human health. The antibacterial modification of flexible polyurethane foam provides a new way to solve this problem.

Polyurethane soft foam can be mainly used in furniture and vehicle seat cushions. These materials often come into contact with large areas of the human body, are easily contaminated with sweat, and cause microbial growth. However, due to their large size, they are difficult to disassemble and clean, causing serious damage to the environment and human body. Health brings hidden dangers. Therefore, the antibacterial and antifungal modification of polyurethane flexible foam has important application value.

The antibacterial modification method of polymer materials is usually achieved by adding antibacterial agents to the system through simple blending technology. There are many kinds of antibacterial agents, which can be roughly divided into three categories according to their chemical composition: natural antibacterial agents, inorganic antibacterial agents and organic antibacterial agents. Among them, natural antibacterial agents are restricted by raw materials and processing conditions, and large-scale marketization has not yet been achieved.

Inorganic antibacterial agents are mainly silver-based antibacterial agents, which have the advantages of safety, heat resistance, and durability. The disadvantages are high price, easy discoloration, slow antibacterial efficiency, and poor compatibility with polymer materials. At this stage, the antibacterial modification methods of polyurethane flexible foam at home and abroad are mainly to directly add inorganic antibacterial agents to the polyurethane raw material system, so that they are physically blended in polyurethane to increase the antibacterial properties of the material. For example, in the patent application document "A Preparation Method for Antibacterial and Mold-proof MDI Memory Polyurethane Foam", Xu Minghong et al. first prepared silver-loaded muscovite powder antibacterial agent, and then added it to the polyurethane reaction system. The prepared polyurethane foam has good antibacterial properties. sex. In the patent application document "An Antibacterial Polyurethane Integral Skin Foam Composition for Seat Armrests", Xia Qingqing et al. used nano-copper as an antibacterial agent and added it to isocyanate to prepare a polyurethane self-skinning foam. The antibacterial rate of the composition reaches more than 95%.

This type of antibacterial polyurethane modified by adding an inorganic antibacterial agent has a large amount of antibacterial agent added, usually greater than 2%, so it has a greater impact on the foaming properties and physical properties of the product. Moreover, its modification method is physical blending, and the product often has the disadvantages of easy discoloration, slow antibacterial efficiency, unsustainable antibacterial property, and unstable release rate of antibacterial agents.

Organic antibacterial agents mainly include quaternary ammonium salts, quaternary phosphonium salts, guanidines, phenols, and pyridines. Organic antibacterial agents have the advantages of fast sterilization speed and wide antibacterial range, but they also have poor heat resistance, easy oozing, and dissolution issues such as toxicity. For example, in the patent application document "A polyurethane cushion material with antibacterial function and its preparation method and application", Li Zhaorong et al. used quinolone antibacterial agents to react with polyisocyanates, and then used modified polyisocyanates to react with polyols to prepare A car seat cushion material with good antibacterial properties. In the journal paper "Bactericidalpolyurethanefoammattresses: Microbiologicalcharacterization and effectiveness" (MaterialsScienceandEngineeringC, 2010, v30, n5, p705-708), V.S.Dagostin et al. added triclosan, isothiazolone, and zinc pyrithione as antibacterial agents to the polyurethane raw material system. , the results show that the addition of isothiazolone and zinc pyrithione modified polyurethane soft foam has better antibacterial properties, and it is found that for zinc pyrithione modified polyurethane, when the addition of zinc pyrithione is 0.50wt%, the polyurethane soft foam is at the same time It has excellent antibacterial properties and low biological toxicity.

However, the above inventions have not verified that the modification methods are simple physical blending, which will cause problems such as easy leakage of antibacterial agents and biological toxicity of materials, and it is difficult to solve the problem of persistence of antibacterial effects.

Contents of the invention

The purpose of the present invention is to solve the above problems by chemically bonding the guanidinium salt antibacterial agent on the polyurethane macromolecular chain to provide a new type of antibacterial polyurethane soft foam with long-lasting, broad-spectrum, high-efficiency, and safe and non-toxic to human health. Preparation.

In order to achieve the above object, the present invention adopts the following technical scheme: a preparation method of antibacterial modified polyurethane flexible foam, which is prepared by prepolymer method, semi-prepolymer method or one-step method from the following substances in weight percentage:

Polyisocyanate 25-40%;

Polyether polyol 50-70%;

Antibacterial agent 0.01~5%;

Other additives 2-10%;

The other auxiliary agents include catalysts, blowing agents, surfactants or crosslinking agents;

The antibacterial modified polyurethane flexible foam has the following structural formula:

where _R1 is

_R2 is

_R3 is

Described antibacterial agent is guanidinium salt oligomer, and its structural formula is:

The average degree of polymerization is n=2.0-80, and the number-average molecular weight is 3.5×10 ² to 1.0×10 ⁴ .

The antibacterial agent is selected from one or more compounds of polybutylguanidine hydrochloride, polyhexylguanidine hydrochloride, polyoctylguanidine hydrochloride or polydecylguanidine hydrochloride.

The polyisocyanate is selected from one of toluene diisocyanate, diphenylmethane diisocyanate or isophorone diisocyanate.

The polyether polyol is selected from one or several compoundings of polyoxypropylene diol, polyoxypropylene triether, high-activity polyether polyol, and polymer polyol.

The catalyst is a composite catalyst composed of a tertiary amine catalyst and an organic tin catalyst.

The tertiary amine catalyst is selected from one or more of triethylenediamine, triethanolamine, bis(dimethylaminoethyl) ether, dimethylcyclohexylamine, dimethylethanolamine; the organic The tin catalyst is selected from one or more of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate and dibutyltin dimaleate.

The foaming agent is deionized water.

The surfactant is selected from organic silicon surfactants containing repeated dimethylsiloxane chain units, oxyethylene chain units, and oxypropylene chain units.

The crosslinking agent is selected from one or more of diethanolamine, triethanolamine, and bis-2-(hydroxypropyl)aniline.

The antibacterial agent used in the present invention is a guanidinium salt oligomer, which is a macromolecular bactericide with high-efficiency broad-spectrum, antibacterial and anti-mildew, fast action speed, stable properties, safe for human body, and excellent performance of being easily soluble in water , is a widely used environment-friendly fungicide.

The terminal group of the guanidinium salt oligomer is a primary amino group (—NH ₂ ), which is easy to react with the isocyanate group (—NCO) of the main raw material polyisocyanate of polyurethane, so that it can be chemically bonded without destroying its antibacterial group guanidine group. Guanidine hydrochloride was introduced into the polyurethane polymer chain in a combined way to achieve the purpose of antibacterial modification.

Guanidine oligomers include the following species: polybutylguanidine hydrochloride (PBMG, x=4), polyhexylguanidine hydrochloride (PHMG, x=6), polyoctylguanidine hydrochloride (POMG, x=6) 8), polydecylguanidine hydrochloride (PDMG, x=10). Its antibacterial property and toxicological safety to human body are characterized by MIC (Minimum Inhibitory Concentration) and hemolytic activity HC ₅₀ (minimum concentration that dissolves 50% red blood cells). The smaller the MIC value, the better the antibacterial property, and the smaller the HC50 value, the greater the toxicity.

Comparing the MIC values of the above guanidine salt oligomers, we can get PBMG>PHMG>POMG, PDMA, and comparing the HC ₅₀ values, we can get PDMG>POMG>PHMG>PBMG. In specific applications, according to the application requirements and cost performance of the materials, a balance between good antibacterial properties and low biological toxicity can be sought, and a suitable guanidinium salt antibacterial agent can be selected.

The main raw materials for the synthesis of flexible polyurethane foam are polyisocyanate and polyether polyol, and the main reactions in the reaction process are as follows:

Reaction 1: Polyisocyanate reacts with polyether polyol to form polyurethane:

R ₁ —NCO+R ₂ —OH→R ₁ —NH—CO—O—R ₂

Reaction 2: Polyisocyanate reacts with water to form an unstable carbamate first, and then decomposes into amine and carbon dioxide, and the amine group further reacts with isocyanate group to form a polymer containing urea group:

R ₁ —NCO+H ₂ O→R ₁ —NH—COOH→R ₁ —NH ₂ +CO ₂ ↑

R ₁ —NCO+R ₁ —NH ₂ →R ₁ —NH—CO—NH—R ₁

where _R1 is _R2 is

Due to the activity of the isocyanate group (-NCO), it can not only react with polyols to form carbamates, but also react with other compounds with active hydrogen, such as with -OH groups (alcohols, phenols, Water, alcohol amines), -NH ₂ groups (amines, urethanes, ureas) and -SH groups (thiols) compounds react.

In the present invention, we use the chemical characteristics that the isocyanate group can react with the amine group, and introduce the antibacterial group guanidine group in the guanidinium salt antibacterial agent into the polyurethane polymer polymer chain in a chemically bonded manner, and carry out antibacterial modification of the polyurethane flexible foam. sex. Its reaction mechanism is as follows, and this reaction carries out simultaneously with above-mentioned reaction one, reaction two:

R ₁ —NCO+R ₃ —NH ₂ →R ₁ —NH—CO—NH—R ₃

Among them, _R3 is

The operation of the prepolymer method is as follows: first react polyether polyol with diisocyanate to generate a low-molecular polymer (prepolymer) with isocyanate groups at the end; The prepolymer is added under high-speed stirring, and the urea group is formed after the reaction, and the foaming reaction is carried out during the chain growth process, and finally the antibacterial modified polyurethane flexible foam is made.

The operation of the semi-prepolymer method is as follows: a part of polyether polyol is reacted with excess diisocyanate to generate a low-molecular-weight polymer with a certain viscosity, and then the remaining polyol in the formula is mixed with water, antibacterial agent, and other auxiliary agents. It is added into the prepolymer, and in the presence of catalyst and surfactant, it is mixed with high-speed stirring and then foamed to finally make antibacterial modified polyurethane soft foam.

The operation of the one-step method is as follows: add polyether polyol, antibacterial agent, deionized water and other additives into the reaction vessel, stir at high speed while adding materials, add polyisocyanate after stirring evenly, and stir again at high speed for foaming , finally made of antibacterial modified polyurethane soft foam.

The present invention has the following advantages and characteristics due to the adoption of the above technical scheme:

1. Antibacterial modification and polyurethane synthesis in one step

Most antibacterial modified polymers are synthesized and processed step by step. Antibacterial modification is carried out in the processing step. First, a large amount of antibacterial agent is mixed with the polymer to make a high-concentration antibacterial masterbatch, and then the antibacterial masterbatch is mixed with Polymers are mixed to produce antibacterial materials or articles.

However, for the preparation of flexible polyurethane foam materials, since the polymerization reaction and the foaming reaction proceed simultaneously, and the reaction is completed within a few minutes, it is difficult to use the masterbatch blending method to modify the antibacterial material. Therefore, the present invention adopts guanidinium salt oligomer as antibacterial agent, and completes antibacterial modification and polyurethane synthesis in one step at the same time, with fast reaction rate and simple operation.

2. Antibacterial modification by chemical bonding

There are few antibacterial researches on polyurethane flexible foam at home and abroad, and its antibacterial modification method is mainly physical blending of inorganic antibacterial agents, the product cannot have long-term antibacterial properties, and the bactericidal efficiency is difficult to control.

The present invention adopts guanidinium salt oligomer as antibacterial agent, makes it react with polyisocyanate in polyurethane raw materials, and introduces guanidinium salt antibacterial agent into polyurethane polymer chain by chemical bonding without destroying the guanidinium group of antibacterial group . And through infrared and ultraviolet spectroscopic tests, it is further confirmed that the modification method is chemical bonding. The prepared polyurethane flexible foam has long-acting antibacterial properties, fast sterilization rate, wide antibacterial range and high storage stability.

detailed description

Embodiment is given below, and following embodiment is only used for further explanation of the present invention, can not be interpreted as the limitation of protection scope of the present invention, the professional of this field can make some non-essential improvement and adjustment to the present invention according to above-mentioned content of the present invention. Because guanidinium salt oligomers of different types and molecular weights such as PBMG, PHMG, POMG, PDMA, etc., in the preparation process of antibacterial polyurethane soft foam, the process is basically the same, so in the following examples, we only use antibacterial activity. PHMG, which is good in human body safety, is the representative to explain.

One, embodiment 1～7 (the antimicrobial modified polyurethane soft foam of different PHMG addition amount):

(1) Preparation of PHMG (polyhexylguanidine hydrochloride) modified polyurethane flexible foam:

Dissolve PHMG in deionized water (foaming agent), mix with polyols, catalysts, foaming agents and other additives in proportion, and stir evenly at high speed. As material A, the amount of PHMG added is 0% of the total amount of PU. %, 0.01%, 0.50%, 1.00%, 2.00%, 3.00%, 5.00%. When stirring material A, the speed of the agitator is 1000-1500r/min. After stirring evenly, add polyisocyanate (material B), stir again at high speed for foaming, the speed of the stirrer is 1500-2000r/min, let stand for 3-5min, and the obtained product is antibacterial modified polyurethane flexible foam.

(2) Washing of PHMG modified polyurethane soft foam:

Wrap the polyurethane sample with filter paper and place it in a Soxhlet extractor, extract with deionized water as a solvent, and extract continuously for 48 hours to remove the unreacted PHMG in the polyurethane, then place the sample in a vacuum oven at 60°C to dry Dry.

(3) Infrared and ultraviolet tests of PHMG modified polyurethane flexible foam

After drying the polyurethane sample after Soxhlet extraction and washing, it was tested by decay total reflectance (ATR) to obtain an infrared spectrum.

A series of standard PHMG solutions with gradient concentrations were prepared, and tested by ultraviolet spectrum, and the ultraviolet absorption peak of PHMG was measured at 192nm ^-1 . Taking the PHMG concentration as the abscissa and the ultraviolet absorption intensity at 192nm ^-1 as the ordinate, a standard curve of the concentration of the PHMG solution and the intensity of the absorption peak can be obtained.

With the washing liquid obtained after washing in Example 1 as a reference solution, the washing liquid obtained after washing in Examples 2 to 7 is subjected to ultraviolet spectrum testing, and its absorption intensity at 192nm ⁻¹ is tested, and compared with the standard curve, The PHMG concentration of the washing solution can be obtained, and the PHMG bonding efficiency in the polyurethane can be obtained after calculation.

Two, embodiment 8～11 (preparation of the antibacterial modified polyurethane flexible foam of different guanidinium salt oligomers):

Dissolve guanidinium salt oligomers PBMG, PHMG, POMG, and PDMG in deionized water (foaming agent), and then mix them with polyols, catalysts, foaming agents and other additives in proportion, stir evenly at high speed, and use them as material A , The addition amount of four kinds of guanidinium salt oligomers is 1.00% of the total amount of PU. When stirring material A, the speed of the agitator is 1000-1500r/min, after stirring evenly, add polyisocyanate (material B), stir again at a high speed for foaming, the speed of the agitator is 1500-2000r/min, let stand for 3-5min, the obtained The product is an antibacterial modified polyurethane flexible foam.

Wrap the polyurethane sample with filter paper and place it in a Soxhlet extractor, extract with deionized water as a solvent, and extract continuously for 48 hours to remove the unreacted PHMG in the polyurethane, then place the sample in a vacuum oven at 60°C to dry Dry.

Three, embodiment 12～14 (the PHMG antibacterial modified polyurethane soft foam that different preparation methods prepare):

(1) Preparation of modified polyurethane by prepolymer method: first react polyether polyol with diisocyanate to generate a low-molecular polymer (prepolymer) with isocyanate groups at the end; The agent is added to the prepolymer under high-speed stirring, and after the reaction, urea groups are formed to form a high polymer, wherein the amount of PHMG added is 1.00% of the total PU.

(2) Preparation of modified polyurethane by semi-prepolymer method: react a part of polyether polyol with excess diisocyanate to form a low molecular weight polymer with a certain viscosity, and then mix the remaining polyol in the formula with water, antibacterial agent, etc. The auxiliary agent is added into the prepolymer, and in the presence of the catalyst and the surface active agent, foaming is carried out after being mixed by high-speed stirring, wherein the added amount of PHMG is 1.00% of the total amount of PU.

(3) One-step preparation of modified polyurethane: add polyether polyol, antibacterial agent, deionized water and other additives into the reaction vessel, stir at high speed while adding materials, add polyisocyanate after stirring evenly, and stir again at high speed for fermentation Foam, finally made into antibacterial modified polyurethane flexible foam, wherein the addition of PHMG is 1.00% of the total PU.

The reaction parameter summary result of embodiment 1～14 is as shown in table 1:

Table 1

testing method

In the embodiment of the present invention, adopted following test method:

Indentation hardness performance testing (load at 25% indentation, load at 65% indentation) refers to GB/T10807-2006.

The performance test result of embodiment 1-14 is summarized as shown in table 2:

Table 2

According to Examples 1-7, when PHMG is added in an amount of 0.01-5 wt%, polyurethane has good antibacterial properties. The addition of PHMG and the change of the amount of PHMG have no obvious effect on the mechanical properties of polyurethane such as density, tensile strength, tear strength, rebound rate, 25% indentation load, and 65% indentation load. Polyurethane still has good bacteriostasis after washing with water, which proves that PHMG is not simply dispersed in polyurethane soft foam by physical blending, but is grafted on the polyurethane polymer chain by chemical bonding.

Comparing the infrared spectra of Example 7 and Example 1, a new absorption peak appeared at 1640cm ^-1 , and 1640cm ^-1 is the stretching vibration absorption peak of the characteristic absorption peak C=N of guanidinium salt, which proves that PHMG has been grafted to polyurethane on the molecular chain.

The ultraviolet spectrum test was carried out on the water washing solution of the flexible polyurethane foam in Examples 2 to 7, and the calculated PHMG grafting efficiency was greater than 40%. When the PHMG addition was 1.0%, the grafting efficiency was the highest, which was 69.1%.

According to Examples 8-14, the antibacterial modified polyurethane soft foam prepared by different guanidinium salt oligomers and methods, its product density and tensile strength, tear strength, rebound rate, 25% indentation load, 65% indentation load The difference in mechanical properties such as sink load is not obvious. The introduction of the guanidinium salt antibacterial agent makes the polyurethane have excellent antibacterial performance, and when the content reaches 0.50wt%, the antibacterial rate reaches more than 99%.

Claims (10)

1. A preparation method for antibacterial modified polyurethane soft foam is characterized in that, it is prepared by prepolymer method, semi-prepolymer method or one-step method by the material of following weight percent: Polyisocyanate 25-40%; Polyether polyol 50-70%; Antibacterial agent 0.01~5%; Other additives 2-10%; The other auxiliary agents include catalysts, blowing agents, surfactants or crosslinking agents; The antibacterial modified polyurethane flexible foam has the following structural formula: where _R1 is _R2 is _R3 is 2. the preparation method of antibacterial modified polyurethane soft foam as claimed in claim 1, is characterized in that, described antibacterial agent is guanidinium salt oligomer, and its structural formula is: The average degree of polymerization is n=2.0-80, and the number-average molecular weight is 3.5×10 ² to 1.0×10 ⁴ . 3. the preparation method of antibacterial modified polyurethane flexible foam as claimed in claim 2, is characterized in that, described antibacterial agent is selected from polybutyl guanidine hydrochloride, polyhexyl guanidine hydrochloride, polyoctyl guanidine One or more compounds of hydrochloride or polydecylguanidine hydrochloride. 4. the preparation method of antibacterial modified polyurethane flexible foam as claimed in claim 1 is characterized in that: described polyisocyanate is selected from toluene diisocyanate, diphenylmethane diisocyanate or isophorone diisocyanate A sort of. 5. the preparation method of antibacterial modified polyurethane flexible foam as claimed in claim 1, is characterized in that: described polyether polyol is selected from polyoxypropylene diol, polyoxypropylene triether, highly reactive polyether polyol Alcohol, polymer polyol or one or several compounding. 6. The preparation method of antibacterial modified polyurethane flexible foam as claimed in claim 1, characterized in that: the catalyst is a composite catalyst formed by compounding a tertiary amine catalyst and an organotin catalyst. 7. the preparation method of antibacterial modified polyurethane soft foam as claimed in claim 6 is characterized in that: described tertiary amine catalyst is selected from triethylenediamine, triethanolamine, bis(dimethylaminoethyl) ) ether, dimethylcyclohexylamine, dimethylethanolamine; the organotin catalyst is selected from dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dibutyltin dimaleate One or more of butyltin. 8. The preparation method of the antibacterial modified polyurethane flexible foam as claimed in claim 1, characterized in that: the foaming agent is deionized water. 9. the preparation method of antibacterial modified polyurethane flexible foam as claimed in claim 1, is characterized in that: described tensio-active agent is selected for use and contains repeated dimethylsiloxane chain unit, oxyethylene chain unit, oxypropylene Chain-linked silicone surfactants. 10. the preparation method of antibacterial modified polyurethane soft foam as claimed in claim 1 is characterized in that: described linking agent is selected from diethanolamine, triethanolamine, two-2-(hydroxypropyl)aniline one or more.