CN104693478A - Polyvinyl alcohol sponge and preparation method thereof - Google Patents

Abstract

The invention discloses a polyvinyl alcohol foaming material and a preparation method thereof. According to the method, the foaming technological process is optimized, so that the product technological stability of the polyvinyl alcohol sponge foaming process is effectively improved, the product service life is effectively prolonged, the problems that the polyvinyl alcohol sponge becomes yellow and is aged when used for a long time on the specific condition are solved, the product quality of the polyvinyl alcohol sponge is improved, and the obtained polyvinyl alcohol sponge has higher application value.

Description

A kind of polyvinylalcohol sponge and preparation method thereof

Technical field

The present invention relates to polyvinylalcohol sponge and preparation method thereof.Industry cleaning link, fast local hemostasis, medical carrier and cold compress and hot compress polyvinyl formal sponge can be widely used in

Background technology

Polyvinyl alcohol (hereinafter referred to as PVA) acetals high-absorbent material has excellent absorbent function, there is good heat-resisting, wear resisting property, obtain in fields such as electronic industry, daily cleaning, health care, material of construction and applied comparatively widely, product has excellent chemical stability, acid-fast alkali-proof performance; Product has high water absorbing capacity and water retention property, and rate of water absorption is fast, and liquid absorbency rate is high, soft fine and smooth after water suction.Because itself should not bacterial growth, after water suction, quality is soft, with normal gauze class, absorbent cotton class, gelatin class hemostatic material by comparison, its hemostasis, to expand and comfort property etc. has a clear superiority in, receive much concern in field of medical materials, market potential is huge.

At present disclosed polyvinyl formal sponge preparation method comprises: pore former foaming, foaming agent foam method, machinery are got blisters method.

Pore former foaming, in polyvinyl alcohol solution, first add pore former, then add tensio-active agent, formaldehyde, acid etc., pore former plays supporting core effect, polyvinyl alcohol is acetalation around pore former, then along with pore former obtains polyethylene foamed alcohol material from removing system.When adopting pore former foaming, also need to add tensio-active agent, to reduce the surface tension of solution, promote the dispersion of pore former between each phase.The kind porous plastics that obtain different pore size and hole count different from consumption of pore former.Starch is conventional pore former, if patent publication No. is in the polyvinyl formal foam preparation processes of CN101508747 and CN101508814, all using kind starch granuless such as tapioca (flour), yam starch, W-Gums as pore former thing, after polyvinyl alcohol curing molding, re-use large water gaging starch wash is fallen.Use the product that this kind of technical matters is produced, starch is more difficult to be cleaned up completely, and residual starch is understood mould growth and causes product to go bad, and limits product application scope.And in this kind of technical matters, starch utility value is low, water loss is large, and starch and acid catalyst can not be recycled, and are unfavorable for economizing on resources and cutting down cost.

Foaming agent foam method, in polyvinyl alcohol water solution, adds tensio-active agent, whipping agent, formaldehyde, acid catalyst etc., after whipping agent and acid catalyst react, produces a large amount of bubble, be dispersed in resin solution.Along with the generation of resin aldolization and crosslinking reaction, obtain polyvinylalcohol sponge.Major part whipping agent adopts carbonate or supercarbonate, and if patent publication No. is adopt sodium bicarbonate to be whipping agent in CN1557872 and CN1095387, but foaming products obtained therefrom sponge foaming bore dia is comparatively large, and is difficult to control evenly.Rapid because of the material such as sodium carbonate or sodium bicarbonate and inorganic acid strong reaction, abrupt release goes out a large amount of gas, and escape of gas is serious, thus sodium carbonate and sodium bicarbonate addition larger, also consume more acid catalyst, this kind of method is higher to processing requirement in suitability for industrialized production simultaneously.

Machinery is got blisters method, when polyvinyl alcohol water solution is cooled to certain temperature, adds tensio-active agent, formaldehyde, acid catalyst etc., high-speed stirring is utilized to be brought in polyvinyl alcohol water solution by air, until volume reach relatively stable after, pour mixed liquor into mould, curing molding.Along with polyvinyl alcohol foam dehydration, sclerosis, form the foam of gas dispersion in polyvinyl formal solid gradually.Machinery method of getting blisters uses reagent less in theory; in field of medical materials, there is larger market potential; but machinery is got blisters, method is higher to processing requirement, and to foaming condition sensitive in amplification process, the constant product quality of its large-scale production process is rich in challenge.

On the one hand, in preparation process, also often occur in polyvinyl alcohol foam process that operating procedure is unstable, such as, because the autoxidation of reaction raw materials makes organic acid content significantly raise in reaction process, polyvinylalcohol sponge quality product will be made to change, cause occurring certain aberration, and even the phenomenon turned yellow, thus reduce sponge yield rate, improve production cost.On the other hand, in polyvinylalcohol sponge product application process, the flavescence of long-time use polyvinylalcohol sponge, problem of aging under also appearing in comparatively high temps, humidity condition.In order to improve polyvinylalcohol sponge production stability further, improve yield rate, reduce production cost, produce the polyvinylalcohol sponge product that quality is more stable, the present invention, by the optimization to production technique, provides a kind of polyvinyl formal sponge material and preparation method thereof.

Summary of the invention

In order to solve polyvinyl alcohol foam material technology stability, and improve product life cycle problem, to in the stability analysis process of polyvinyl alcohol foam, find that pH value has larger impact for polyvinylalcohol sponge foaming process, acid residual in system is under high temperature, super-humid conditions, product can be caused to turn yellow, even cause sponge material sex change, cause sponge performance obviously to decline, reduce the product life of sponge.It is worth mentioning that in foaming process, acetalation is wherein important step, namely under an acidic catalyst existent condition, aqueous temperature control 40-80 DEG C, utilize other material occupy-places, make polyvinyl alcohol crosslinked formation pore space structure by aldehyde (mainly formaldehyde), prepare porous material.But under this condition, aldehydes generation side reaction, obtains acid, peroxy acid etc. are a series of has corrosive impurity.Cause on the one hand, in process of production, as: in aldolization, curing molding, foam material post-treating and other steps, impurity destroys polyvinyl alcohol original structure under the aqueous conditions of certain temperature, make product variable color, cause the quality of polyvinylalcohol sponge product unstable, fraction defective improves, and virtually adds production cost.On the other hand, because the affinity of such material and polyvinyl alcohol material is stronger, even can with polyvinyl alcohol generation bonding action, even if a large amount of water washings is more difficult removing also, this will directly cause polyvinylalcohol sponge bad stability in the process used, variable color, aging, reduction of service life.For solving the problem, the invention provides a kind of optimization method preparing polyvinyl alcohol foam material, and a kind of stable polyvinyl alcohol foam material utilizing the method to obtain.

Preparation method provided by the invention comprises: (a) prepares polyvinyl alcohol solution; (b) configuration frothing solution; (c) aldolization; (d) curing molding; E the aftertreatment of () foam material, comprises the demoulding; Washing; Extrusion dehydration; Dry; The steps such as machine-shaping, its feature is, in the process of preparation, (a) to (e) one or more step is carried out in shielding gas atmosphere.

Preferably, described preparation method, is characterized in that, describedly configures frothing solution at (b); (c) aldolization; (d) curing molding; E, in () foam material post-processing step, at least one step is carried out in shielding gas atmosphere.

Preferably, described preparation method, is characterized in that, preheats described shielding gas.

Preferably, described preparation method, is characterized in that, describedly configures frothing solution step at (b) and carries out in shielding gas atmosphere.

Preferably, described preparation method, is characterized in that, replaces after (a) prepares polyvinyl alcohol solution with shielding gas to reaction system.

Preferably, described preparation method, is characterized in that, described (b) configure frothing solution at least comprise mechanical foaming and/or pore former foaming in one or more combination.

Preferably, described preparation method, is characterized in that, described shielding gas be selected from nitrogen, carbon dioxide, argon gas, helium, oxygen-denuded air, water vapour, other not with system reactant gases etc.

Preferably, described preparation method, is characterized in that, described shielding gas adopts Bubbling method, sweeping method, paddling process to enter reactive system.

Stable polyvinyl alcohol foam material provided by the invention, is characterized in that, described sponge organic acid content amount is less than 100mg/100g, is greater than 0.01mg/100g; Preferred organic acid content is less than 80mg/100g, is greater than 0.05mg/100g; Preferred organic acid content is less than 50mg/100g, is greater than 0.1mg/100g; Preferred organic acid content is less than 10mg/100g, is greater than 0.5mg/100g; Preferred organic acid content is less than 5mg/100g, is greater than 0.5mg/100g; Preferred organic acid content is less than 5mg/100g, is greater than 1mg/100g.

Preferably, described polyvinyl alcohol foam material, is characterized in that organic acid be organic acid is formic acid, acetic acid, peroxyformic acid, Peracetic Acid and composition thereof.

The beneficial effect of the invention

The invention provides a kind of preparation method of polyvinylalcohol sponge, the generation of side reaction in effective inhibition system, reduce the residual of corrosives, make operating procedure more stable, further raising polyvinylalcohol sponge products production stability, improve yield rate, effectively reduce production cost, the polyvinylalcohol sponge product that quality is more excellent can be produced.Sponge material uniform pore diameter, the feel of preparation are fine and smooth, have longer work-ing life, have higher using value under relative exacting terms.

Embodiment:

Below in conjunction with embodiment, embodiment of the present invention are described in detail, but it will be understood to those of skill in the art that the following example only for illustration of the present invention, and should not be considered as limiting scope of the present invention.Unreceipted actual conditions person in embodiment, the condition of conveniently conditioned disjunction manufacturers suggestion is carried out.Agents useful for same or the unreceipted production firm person of instrument, being can by the conventional products of commercial acquisition.

The various term used in invention and phrase have and well known to a person skilled in the art general sense, but have special definition in this article, are as the criterion with implication as defined herein.

After " pending foam material " refers to curing molding, until before completing and being packaged into qualified foamed products for sale, the intermediates of each aftertreatment link.

" oxygen-denuded air " is by relative inertness such as nitrogen, carbon dioxide, argon gas, helium, water vapour, joins in air on the less gas of reaction system impact, the mixed gas obtained.Object mainly reduces the oxygen content in air, reduces the generation of side reaction, improves the quality of products.Generally control oxygen content between 0.1-15% (volume).

" foam material aftertreatment " generally comprises the demoulding; Washing; Extrusion dehydration; Dry; The steps such as machine-shaping, also can increase certain operation steps according to product applications difference, as: dry; Freeze-drying; Sterilizing; Packaging; The middle-chain such as to soak into.

" composite foamable agent " had both comprised the combination of two or more whipping agent, also comprised based on one or more Blowing agent composition, by adding other components, and the composite foamable agent playing enhanced foaming effect, improve bubbling efficiency, reduce the performances such as blowing temperature.

" water-intake rate " method of calculation, measure the foam materials initial weight (A) of certain specification, this foam sample is placed in distilled water to be dipped to saturated, place after taking out from water and within 30 seconds, weigh (B), with formulae discovery the following: water-intake rate (%)=(B-A)/A × 100%.Replicate measurement 3 times, averages.

Formic acid detection method: the formic acid detection method for trace is more, representative as CN101324515A; CN101324516A; CN102305835B " Journal of ChromatographyB ", the 1999,734th volume, 155-162; CN202903734U; CN103743729A; CN103954523A etc.

Polyvinylalcohol sponge hot water stability tests: get a certain amount of polyvinyl sponge sample, be positioned in 60-100 DEG C of distilled water, keep this temperature, places certain hour.Contrast with the standard model of 60 DEG C of distilled water immersions.

Concrete operations are as follows:

A () prepares polyvinyl alcohol solution: get a certain amount of polyvinyl alcohol and mix with water, under churned mechanically condition, system temperature is risen to suitable temperature, polyvinyl alcohol is fully dissolved, stirs into solution;

(b) configuration frothing solution: proportionally get polyvinyl alcohol solution prepared by step (a); shielding gas is passed in system; removing residual air; control stirring velocity, according to the concrete foaming method adopted, select suitable stirring velocity; suitable mixing temperature; select to add appropriate whipping agent and/or pore former, and dispersion agent etc., be stirred to system even.

C () aldolization: under the condition of gas shield, in the dispersed system that step (b) obtains, proportionally adds catalyzer, linking agent respectively, can select suitable to add suds-stabilizing agent, stirs 2-20 minute.

(d) curing molding: under the condition of gas shield, slip step (c) be stirred pours in mould, control temperature 50-80 DEG C, insulation 2-20 hour;

E () foam material aftertreatment: under the condition of gas shield, removes after foam material being down to room temperature from mould; Wash with water; And then by dehydration; Dry; Machine-shaping; Degerming sterilization; The steps such as encapsulation storage obtain target product.

In step (a) to (e) process, concrete technology parameter is as follows:

In order to obtain in best mixing effect step (a) to (e) process, multi-layer oar blade can be adopted to stir, the whipping appts of preferably 2 layers, more than 3 layers or 3 layers; Rotating speed adjusts according to concrete steps processing parameter demand, generally selects between 100-1500 rev/min.

In step (a) to (e) process, heating can adopt the type of heating such as oil bath, steam, heating jacket, heating pipeline.

In step (a) to (e) process, shielding gas is selected from nitrogen, carbon dioxide, argon gas, helium, oxygen-denuded air, other rare gas elementes etc.

In step (a) to (e) process, preferred gas shield scheme is, shielding gas can, according to the needs of different step, adopt Bubbling method, sweeping method, paddling process to enter system.First conversion unit is carried out to the displacement of shielding gas and air in the ordinary course of things, to ensure that foaming system is under the atmosphere of sufficient shielding gas, for the production unit of different scales, the protected mode selected slightly affects for quality product.Find in experimentation, the more long-acting fruit of time swap is better, but the long time is not suitable for products production, and generally the selective cementation time is as required: 0.5-30 minute, and the preferred time is 1-20 minute, and more preferably the time is 5-10 minute.

In described step (a), preparing in polyvinyl alcohol solution process and can selecting gas shield, in the process adding polyvinyl alcohol, with the air in protective gas displacement container, the method for bubbling can be adopted to be punched in solution by shielding gas.

In described step (a), preparing in polyvinyl alcohol solution process, also directly can utilize shielding gas liquid purge solution surface, in the process of the mixing of stirring, along with shielding gas is brought in solution by churned mechanically carrying out.

In described step (a); when the shielding gas Bubbling method of lesser temps is passed into aqueous systems; the dissolution time needing more to grow of polyvinyl alcohol or higher stirring velocity; when not changing stirring velocity and time, polyvinyl alcohol mixing even results has decline to a certain degree to cause the degree of uniformity of polyvinylalcohol sponge to decline to some extent.Preferably protection scheme preheats shielding gas, and the temperature of shielding gas controls at 50-100 DEG C, and preferable temperature is 60-95 DEG C, and preferable temperature is 70-90 DEG C.In described step (a), according to the solubility property of the different polyvinyl alcohol raw material of raw material, stirring velocity required for dissolving and dissolution time slightly difference, stirring velocity can be selected in 500-1200 rev/min, preferred stirring velocity is 600-800 rev/min, but for easily producing the material system of bubble, suitably should reduce stirring velocity, preferred stirring velocity control 100-300 rev/min, preferred stirring velocity control 100-200 rev/min.Along with the raising of stirring velocity and solvent temperature, dissolution rate is very fast, generally can form solution at 30-120 minute.

In described step (a), polyvinyl alcohol can be selected between mean polymerisation degree 400-3000, and alcoholysis degree is between 60-100%, and the scope of molecular weight is at 3-25 ten thousand.The preferably polyethylene alcohol polymerization degree is 400-600, and alcoholysis degree is between 60-90%, and molecular weight is 1-6 ten thousand.The preferably polyethylene alcohol polymerization degree is 800-2000, and alcoholysis degree is between 60-98%, and molecular weight is 3-20 ten thousand.

In described step (a), the weight ratio that material polyethylene alcohol mixes with water controls at 5-20%.

In described step (a), adopt the mode of water vapour heating, also can adopt the type of heating such as oil bath heating.In described step (a), according to material polyethylene alcohol molecular weight, and alcoholysis degree difference can select different solvent temperatures, solvent temperature can control at 60-100 DEG C, preferable temperature is 60-95 DEG C, preferable temperature is 70-90 DEG C, for special polyvinyl alcohol raw material also can be preferably higher temperature as 95-100 DEG C.

In described step (b); before getting polyvinyl alcohol solution; shielding gas is utilized to purge reactor; air in replacement reaction kettle; after 1-30 minute; add polyvinyl alcohol solution, and carry out follow-up mechanical foaming under shielding gas existent condition, and/or add the operations such as corresponding pore former, whipping agent, auxiliary foaming additive.

In described step (b); when the protection gas of lesser temps is passed into foaming system; the cryogenic gas degree of uniformity of sponge after the foaming that makes that contacts with the polyvinyl alcohol water solution of temperature comparatively high temps declines to some extent; affect degree of crosslinking to a certain extent simultaneously; apparent density is relatively low; this phenomenon is at foaming agent foam, and comparatively obvious in pore former foaming process.Preferably protection scheme preheats shielding gas, and the temperature of shielding gas controls can control at 30-90 DEG C in solvent temperature; Preferable temperature is 40-80 DEG C.

In described step (b), system temperature controls at 30-90 DEG C; Preferable temperature is 40-80 DEG C.

In described step (b), if adopt mechanical foaming method, higher stirring velocity can be selected, 500-1500 rev/min; Preferred stirring velocity is 700-1400 rev/min; Preferred stirring velocity is 800-1300 rev/min, selects suitable stirring velocity to be conducive to foam material pore even, thus the foaming effect that impact is overall.

In described step (b), also can select the method adopting mechanical foaming method to combine with foaming agent foam method, control stirring velocity, 500-1200 rev/min; Preferred stirring velocity is 600-1000 rev/min; Preferred stirring velocity is 700-900 rev/min.

In described step (b), mechanical foaming method is by high-speed stirring time controling at 5-60 minute, and the preferred time is 10-30 minute, and system has larger viscosity, and churning time is too short will affect distributed effect.

In described step (b), also can select the method adopting mechanical foaming method to combine with foam agent foaming method, control stirring velocity, 500-1200 rev/min; Preferred stirring velocity is 600-1000 rev/min; Preferred stirring velocity is 700-900 rev/min.

In described step (b), also can select, in the technical scheme adopting mechanical foaming method to combine with foaming agent foam and/or foam agent foaming method, can select under stirring at low speed condition, after adding whipping agent and/or foam agent, improve stirring velocity, stir 2-30 minute.

In described step (b), also can select, in the technical scheme adopting mechanical foaming method to combine with foaming agent foam and/or foam agent foaming method, preferably under high-speed stirring condition, to add whipping agent and/or foam agent.

In described step (b), whipping agent can select inorganic foaming agent, one or more as salt of wormwood, in saleratus, calcium carbonate, Calcium hydrogen carbonate, sodium carbonate and sodium bicarbonate.

In described step (b), due to will an acidic catalyst be selected in follow-up aldolization, therefore alkaline whipping agent will consume a certain amount of acid catalyst, affect subsequent reactions effect, simultaneously due to neutralization of acid with base, make whipping agent discharge more gas at short notice at higher temperature, thus affect foaming effect, technology controlling and process is comparatively complicated, and therefore preferably whipping agent is non-alkaline whipping agent.

In described step (b), organic blowing agent Cellmic C 121 (AC), Diisopropyl azodicarboxylate (AI BN), dinitrosopentamethylene tetramine (DPT), dinitroso pentamethylene tetramine, nitroso-group trimethylene tricrotonylidene tetramine, benzol sulfohydrazide, 4 can be selected, one or more in 4 '-OBSH (OBSH), p-toluene sulfonyl hydrazide (TSH), disulfonyl hydrazide sulfobenzide, benzene disulfohydrazide, p-toluene sulfonylsemicarbazide and phenylsulfonamido urea; The whipping agent that preferably can use at a lower temperature, as: one or more in Cellmic C 121 (AC), p-toluene sulfonyl hydrazide (TSH), Diisopropyl azodicarboxylate (AI BN), and its composite foamable agent.

In described step (b), common pore former can be selected, as the natural origin such as starch, polysaccharide pore former, but in view of the pore formers such as starch exist certain defect, pore former can select the pore former being not suitable for bacterial growth or having certain bacteriostatic action, as organic pore former, as propyl alcohol, Virahol, glycerol, ethylene glycol, polyoxyethylene glycol, ethyl acetate, ethyl propionate, polyvinylpyrrolidone, polyacrylamide, sodium cellulosate, tetrahydrofuran (THF), kerosene, whiteruss, hexane, pentane, sherwood oil and methylethylketone etc.

In described step (b), system, except adding appropriate whipping agent and/or foam agent, can be selected to add dispersion agent, and raising whipping agent and/or foam agent, at the dispersity of system, improve the foaming effect of product.Dispersion agent sodium lauryl sulphate, Sodium dodecylbenzene sulfonate, silicone oil, stearic acid, Yelkin TTS, glycerin fatty acid ester, lipid acid sorb are smooth, one or more in polysorbate, sulfated castor oil, dioctyl succinate disulfonate acid and benzalkonium chloride.

In described step (b), add whipping agent after can selecting first to add dispersion agent again or add dispersion agent again after adding whipping agent, after preferably adding whipping agent, after stirring 1-20 minute, adding dispersion agent.

In described step (b), can select first to add emulsifying agent, emulsifying agent is one or more in soap, gum arabic, sodium alkyl benzene sulfonate, ethoxylated dodecyl alcohol, polyoxyethylene stearic acid ester, Glycerol dimer polypropylene glycol ether, di-isopropyl sodium naphthalene sulfonate, spermaceti alcohol radical sodium sulfate and polyoxyethylene carboxylate phosphoric acid salt.

In described step (b), reinforced weight ratio is: PVA solution/whipping agent/dispersion agent=100/0.01-0.5/0-2.5.

In described step (b), reinforced weight ratio is: PVA solution/pore former/dispersion agent=100/0.01-0.5/0-2.5.

In described step (c), in view of system in (b) step is under the atmosphere of shielding gas, and be full of by protective gas in solution system, what this step can not be extra carries out shielding gas process.But; for preventing in heat-processed because temperature fluctuation causes respiration to cause system to be mixed into other materials; preferred in reinforced process; and in cross-linking process, utilize shielding gas to purge system; or selective system reacts under shielding gas atmosphere, be placed in shielding gas atmosphere by reaction system surface.The shielding gas temperature preferably selected controls at 30-90 DEG C; Preferable temperature is 40-80 DEG C.

In described step (c), the weight ratio that emulsifying agent feeds in raw material is: PVA solution/emulsifying agent=100/0-10.

In described step (c), reinforced weight ratio is: PVA solution/linking agent/catalyzer=100/1-15/1-25; Preferred proportion is: PVA solution/linking agent/catalyzer=100/3-12/5-20; Preferred proportion is: PVA solution/linking agent/catalyzer=100/6-10/10-15.

In described step (c), described linking agent is formaldehyde, paraformaldehyde or formaldehyde solution, acetaldehyde, oxalic dialdehyde, propionic aldehyde, butyraldehyde, suceinic aldehyde, glutaraldehyde, lauryl aldehyde (lauric aldehyde), tridecyl aldehyde, myristic aldehyde (tetradecyl aldehyde), methylhexyl acetaldehyde, methyl octyl acetaldehyde, methyl nonyl acetaldehyde, trimethylammonium hexanal, phenyl aldehyde, phenylacetic aldehyde, phenylpropyl aldehyde, cinnamic aldehyde, α-methyl-p-tert.-butyl phenylpropionaldehyde, vanillin food grade,1000.000000ine mesh, one or more mixing in vanirone.

In described step (c), described catalyzer is one or more in hydrochloric acid, phosphoric acid, nitric acid, sulfuric acid.

In described step (c), because polyvinyl alcohol solution itself has surfactivity, under the condition such as adding suds-stabilizing agent, still can form comparatively stable foamy structure, therefore can select in system not add suds-stabilizing agent.Can need to add suds-stabilizing agent according to foam process to better regulate and control foamy structure, suds-stabilizing agent can select in polyacrylamide, albumen, polypeptide, starch, Mierocrystalline cellulose, dimethyl dodecyl amine oxide, polyoxyethylene glycol, monoethanolamine, diethanolamine one or more.

In described step (c), the weight ratio that suds-stabilizing agent feeds in raw material is: PVA solution/suds-stabilizing agent=100/0-10.

In described step (c), after step (b) system is uniformly dispersed, stirring velocity can be selected in 500-1500 rev/min; Preferred stirring velocity is 800-1200 rev/min.Adding catalyzer, after linking agent, reduce stirring velocity to 300-800 rev/min, preferred stirring velocity is 400-600 rev/min, finally add suds-stabilizing agent, stir 5-20 minute, and progressively reduce stirring velocity, stop until stirring, standing preparation is transferred to mould thus carries out step (d) curing molding.

In described step (d), in view of system in step before has taked gas shield measure, and under most of system has been in the atmosphere of shielding gas, this step additionally can not carry out shielding gas conservation treatment.But, for preventing system in transfer process to be mixed into other materials, preferably in material transfer process; shielding gas is utilized to purge mould; 5-10 minute, and with shielding gas, mould and corresponding heating installation thereof are carried out processing, filling, be full of with shielding gas after purging.System in curing molding process is in shielding gas atmosphere as much as possible.Simultaneously due to transfer and heat curing process that step (d) is thermal material, shielding gas still has necessity of preheating, and during preferred operation, shielding gas is preheated 50-80 DEG C, preferable temperature is 60-70 DEG C.

In described step (d), curing molding temperature controls at 50-80 DEG C, and preferable temperature is 60-70 DEG C.

In described step (d), solidified forming time 2-20 hour, the preferred time is 5-10 hour.

In described step (d), can select to carry out in confined conditions, also can select in unlimited system.

In described step (e), heating systems progressively can be down to room temperature, can select to be quickly cooled to room temperature simultaneously.

In described step (e), can select in temperature-fall period under shielding gas existent condition, cooling process is carried out to system.

In described step (e), after foam material can place for some time in a mold, then remove from mould.

In described step (e), foam material remove from mould rear need with a large amount of water cleaning, can by measure elutant pH value, measure organic content determine clean whether meet the requirements.Can think that after massive laundering foam material is in steady state substantially, the chance of follow-up generation side reaction is less, can select to remove gas shield.

In described step (e), in the product obtained after cleaning, absorb a large amount of moisture, can take to extrude, centrifugal, freeze-drying, the moisture that comprises in oven dry or its method removing sponge combined.

In experimentation, when finding that relatively low temperate protective gas enters foaming system, there is impact in various degree for foaming process.In step (a) to (e) process; preferred gas shield scheme is; preheat shielding gas before shielding gas is introduced foaming system, pre-heating temperature controls in the corresponding temperature range of this step, or controls in the temperature a little less than this step.As: in (a) step; the temperature of the aqueous solution controls at 60-100 DEG C; shielding gas temperature controls between 50-100 DEG C less on the impact in system, and preferable temperature can control at 60-90 DEG C, and namely preheating temperature controls in foaming system temperature ± 10 DEG C is more rational scope.

Embodiment 1

A () prepares polyvinyl alcohol solution, be carry out stirring into polyvinyl alcohol solution in the water of 60-80 DEG C by the polyvinyl alcohol of 15 parts 200 parts of (weight) temperature;

(b) configuration frothing solution: get the polyvinyl alcohol solution 100g that step (a) configures, blast carbon dioxide in system, 5-10 minute, keep carbon dioxide atmosphere, be heated to 40-50 DEG C, control stirring velocity 1000-1300 rev/min, stir 20-30 minute;

(c) aldolization, keep carbon dioxide atmosphere, control stirring velocity 800-900 rev/min, add hydrochloric acid 15g, stir 10-20 minute, add formaldehyde 15g, reduce stirring velocity to 700-800 rev/min, stir 10-30 minute, add 0.3g suds-stabilizing agent OP-10, and progressively reduce stirring velocity, stop until stirring, process is about 5-10 minute.

D () curing molding: the slip (c) be stirred is circulated in the mould after carbon dioxide replacement, control temperature 60-80 DEG C, was incubated after 3-5 hour.

(e) foam material aftertreatment: foam material is removed from mould; With a large amount of water washings; Foam material dewaters; Dry; Machine-shaping obtains foamed products Y1.

Embodiment 2

A () prepares polyvinyl alcohol solution, under the condition of nitrogen protection, be in the water of 60-80 DEG C, stir into polyvinyl alcohol solution by the polyvinyl alcohol of 10 parts 200 parts of (weight) temperature;

(b) configuration frothing solution: get the polyvinyl alcohol solution 100kg that step (a) configures, join and be full of in the reactor of nitrogen, be heated to 40-50 DEG C, control stirring velocity 600-700 rev/min, add blowing agent AC (Cellmic C 121) 0.5kg, stir 5-10 minute, add dispersion agent 1kg; Stir 5-20 minute;

(c) aldolization, in nitrogen atmosphere, control stirring velocity 700-1200 rev/min, add hydrochloric acid 10kg, stir 10-20 minute, add formaldehyde 12kg, reduce stirring velocity to 400-500 rev/min, stir 10-30 minute, add 0.3kg suds-stabilizing agent OP-10, and progressively reduce stirring velocity, stop until stirring, process is about 5-20 minute.

D shaping slurry to be solidified is transferred in mould by (), be warming up to 90 DEG C, and keeps this temperature 5 hours.

(e) foam material aftertreatment: after curing molding, foaming system is down to room temperature, foam material is removed from mould; Washing; Extrusion dehydration; Dry; Machine-shaping obtains foamed products Y2.

Embodiment 3

A () prepares polyvinyl alcohol solution, under the condition of nitrogen protection, be in the water of 70-90 DEG C, stir into polyvinyl alcohol solution by the polyvinyl alcohol of 20 parts 200 parts of (weight) temperature;

(b) configuration frothing solution: get the polyvinyl alcohol solution 100kg that step (a) configures, join in reactor, be heated to 40-50 DEG C, control stirring velocity 700-800 rev/min, add blowing agent AC (Cellmic C 121) 0.5kg, stir 5-10 minute, add dispersion agent 1kg; Stir 5-20 minute;

(c) aldolization, in the atmosphere of oxygen-denuded air (air and nitrogen 1/1 volume mixture), control stirring velocity 700-1200 rev/min, add hydrochloric acid 10kg, stir 10-20 minute, add formaldehyde 12kg, reduce stirring velocity to 400-500 rev/min, stir 10-30 minute, add 0.3kg suds-stabilizing agent OP-10, and progressively reduce stirring velocity, stop until stirring, process is about 5-20 minute.

D shaping slurry to be solidified is transferred in mould by (), be warming up to 90 DEG C, and keeps this temperature 10 hours.

(e) foam material aftertreatment: after curing molding, foaming system is down to room temperature, foam material is removed from mould; Washing; Extrusion dehydration; Dry; Machine-shaping obtains foamed products Y3.

Embodiment 4

A () prepares polyvinyl alcohol solution, under the condition of nitrogen protection, be in the water of 70-90 DEG C, stir into polyvinyl alcohol solution by the polyvinyl alcohol of 20 parts 200 parts of (weight) temperature;

(b) configuration frothing solution: get the polyvinyl alcohol solution 100kg that step (a) configures, join in the reactor being full of oxygen-denuded air (air and nitrogen 1/2 volume mixture), be heated to 40-50 DEG C, control stirring velocity 700-800 rev/min, add blowing agent AC (Cellmic C 121) 0.5kg, stir 5-10 minute, add dispersion agent 1kg; Stir 5-20 minute;

(c) aldolization, in the atmosphere of oxygen-denuded air (air and nitrogen 1/2 volume mixture), control stirring velocity 700-1200 rev/min, add hydrochloric acid 10kg, stir 10-20 minute, add formaldehyde 12kg, reduce stirring velocity to 400-500 rev/min, stir 10-30 minute, add 0.3kg suds-stabilizing agent OP-10, and progressively reduce stirring velocity, stop until stirring, process is about 5-20 minute.

D shaping slurry to be solidified is transferred in the mould that oxygen-denuded air (air and nitrogen 1/2 volume mixture) replaces by (), be warming up to 90 DEG C, and keep this temperature 10 hours.

(e) foam material aftertreatment: after curing molding, foaming system is down to room temperature, foam material is removed from mould; Washing; Extrusion dehydration; Dry; Machine-shaping obtains foamed products Y4.

Comparative example

Comparative example operation is identical with embodiment 1, but does not carry out gas shield process to systems equipment.

A () prepares polyvinyl alcohol solution, be carry out stirring into polyvinyl alcohol solution in the water of 60-80 DEG C by the polyvinyl alcohol of 15 parts 200 parts of temperature;

(b) configuration frothing solution: get the polyvinyl alcohol solution 100g that step (a) configures, be heated to 40-50 DEG C, control stirring velocity 1000-1300 rev/min, stir 20-30 minute;

(c) aldolization, control stirring velocity 800-900 rev/min, add hydrochloric acid 15g, stir 10-20 minute, add formaldehyde 15g, reduce stirring velocity to 700-800 rev/min, stir 10-30 minute, add 0.3g suds-stabilizing agent OP-10, and progressively reduce stirring velocity, stop until stirring, process is about 5-10 minute.

D () curing molding: the slip (c) be stirred is circulated in mould, control temperature 60-80 DEG C, was incubated after 3-5 hour.

(e) foam material aftertreatment: foam material is removed from mould; With a large amount of water washings; Foam material dewaters; Dry; Machine-shaping obtains foamed products Y0.

Formic acid detects

Sample configures

Get 100g polyethylene foamed alcohol material sample, in the 200mL NaOH aqueous solution (1M), filter after soaking 30mi n, water intaking is concentrated into 10-20mL mutually, detects after getting appropriate amount of sample adjust ph 2-3.

GC chromatographic instrument is analyzed:

Detector is thermal conductivity detector; Chromatographic column is: 1.5m*3mm stainless steel tube; Weighting material, stationary phase: sebacic acid, carrier: GDX-10360-80 order; Analytical procedure, vaporizer temperature: 150 DEG C, sensing chamber's temperature: 150 DEG C, post case temperature: 110 DEG C, bridge electric current: 135mA, flow rate of carrier gas: 50mL/mi n.Adopt ethyl acetate marker method.Retention time is, 0.8mi n, and ethyl acetate retention time is 1.5min.According to formic acid and interior mark peak area, and interior mark addition, conversion formic acid samples contg.

Table 1 foam material Y performance comparison

Claims (10)

1. polyvinylalcohol sponge preparation method, comprising: (a) prepares polyvinyl alcohol solution; (b) configuration frothing solution; (c) aldolization; (d) curing molding; E the aftertreatment of () foam material, its feature is, carries out in shielding gas atmosphere in (a) to (e) one or more step.

2. preparation method according to claim 1, is characterized in that, describedly configures frothing solution at (b); (c) aldolization; (d) curing molding; E, in () foam material post-processing step, at least one step is carried out in shielding gas atmosphere.

3. preparation method according to claim 1, is characterized in that, preheats described shielding gas.

4. preparation method according to claim 1, is characterized in that, described (b) configure frothing solution at least comprise mechanical foaming and/or pore former foaming in one or more combine.

5. the preparation method described in any one of claim 1-4, is characterized in that, described shielding gas is selected from nitrogen, carbon dioxide, argon gas, helium, oxygen-denuded air, water vapour.

6. the preparation method described in claim 1-4, is characterized in that, described shielding gas adopts Bubbling method, sweeping method, paddling process at least one to enter reactive system.

7. a polyvinylalcohol sponge, is characterized in that, described sponge organic acid content is less than 100mg/100g, is greater than 0.01mg/100g.

8. polyvinylalcohol sponge according to claim 7, is characterized in that, described organic acid content is less than 50mg/100g, is greater than 0.05mg/100g.

9. polyvinylalcohol sponge according to claim 8, is characterized in that, described organic acid content is less than 10mg/100g, is greater than 0.05mg/100g; Preferred described organic acid content is less than 10mg/100g, is greater than 0.5mg/100g; More preferably organic acid content is less than 5mg/100g, is greater than 0.5mg/100g; More preferably organic acid content is less than 5mg/100g, is greater than 1mg/100g.

10. polyvinylalcohol sponge according to claim 8, is characterized in that, described organic acid is formic acid, acetic acid, peroxyformic acid, Peracetic Acid mixture.