SK281537B6 - Polymeric water-soluble biodegradable material and method for its preparation - Google Patents

Abstract

The polymeric water-soluble biodegradable material consists of polyvinyl alcohol with a degree of hydrolysis of 70 to 99% and a viscosity of 3 to 35 mPas and natural oligomer to polymer with a relative average molecular weight of 3000 to 30000, filler and / or biologically active compounds in an amount of 85 to 5% by weight. . The process for preparing a polymeric water-soluble biodegradable material is to treat polyvinyl alcohol and / or partially saponified polyvinyl acetate by melting the mixture of components in solid form to form a homogeneous melt that can be directly formed into a finished product, such as water-soluble films, endless fibers or a water-soluble fusible granulate. The preparation of a polymeric water-soluble biodegradable material can also be accomplished by forming the components of the biodegradable material, after formulation and reacting in the form of an aqueous solution, sol or dispersion, directly or to be dried to form a fine, easy to apply material.

Description

Technical field

The invention relates to a polymeric water-soluble biodegradable material resulting from the mutual reaction of polyvinyl alcohol and / or partially saponified polyvinyl acetate and a natural oligomer by mixing them together in solution or by thermoplastic processing in an extruder. Depending on the ratio of polyvinyl alcohol and natural oligomer, the new material is suitable for the production of films, fibers, molded products for various applications as an additive serving as a carrier or encapsulant, especially in agriculture and consumer chemistry, for the production of environmental adhesives and the like. are characterized by improved ecological properties.

BACKGROUND OF THE INVENTION

Several types of water-soluble film-forming and fiber-forming materials based on polyvinyl alcohol (PVA) are known, which are used for various purposes in agriculture and for packaging various products intended to dissolve in water in consumer chemistry. Polyvinyl alcohol, produced by several world producers (Hoechst, Kuraray, Wacker, Rhône Poulang), needs additional treatment with low-molecular plasticisers, making it workable to the desired product.

A method for preparing films and other PVA products was among the first described in the patent literature of Tagikawa et al. (US Pat. 3607812) already wrecked in 1971. Recently, research has focused on the formation of compositions with other polymeric components while using several types of plasticizers.

An interesting water-soluble polymer blend for film preparation was presented by Wysang R.D. vUS Pat. The mixture consists of a low and medium molecular PVA and a copolymer of vinyl alcohol and an ethylenically unsaturated ester. Polyethylene glycol is used as plasticizer. The films are intended for packaging powdery materials so that they can be directly dissolved in water, eliminating the problems of contact and accurate weighing of the contents of the package.

Sonnenstein G. G. in US Pat. No. 4,692,494 discloses water-soluble films based on PVA and polyacrylic acid. The films of the blend of the two polymers dissolve rapidly in cold water, exhibiting high strength, transparency, non-tack, and environmental compatibility. Improvement of the properties was achieved by the addition of a plasticizer and an effective amount of the biocidal product was used for the products.

US Pat. No. 5,449,000 (Robertson L. M. et al.) Discloses extrudable PVA blends containing polyester-polyether block copolymers in an amount of 5 to 25 wt%, e.g. Polyethylene terephthalate block copolymer with polytetrahydrofuran. In particular, an improvement in toughness has been achieved.

Famili A. et al. in US Pat. No. 5,362,778 discloses an extrudable mixture of PVA with modified starches. The thermally modified starch composition is characterized by reduced water sensitivity, improved strength modulus and reduced deformability at relatively high air humidity. Emphasis is placed on the extrusion process, which requires the addition of sufficient energy to the composition to substantially eliminate crystallinity. At sufficient speed, when the PVA cannot decompose yet, the simultaneous energy must be eliminated.

US Pat. 5206278 relates to an extrudable mixture of PVA with a thermoplastic polyethylene oxide having a relative molar mass of 100000 to 2000000, represented in an amount of 5 to 95% by weight. The thermoplastic polyethylene oxide may be added to the PVA prior to homogenization.

As a rule, the extrudable PVA-based compositions do not have sufficiently balanced properties, such as rapid cold water solubility, high strength with high biodegradability, which is currently of particular environmental importance. Known and undoubtedly positive results are exploited and problems are solved by the new PVA-based material and natural oligomer, which is rapidly soluble in cold water and fully compatible with the bacterial flora of the soil, which rapidly biodegrades it.

SUMMARY OF THE INVENTION

The solution according to the invention is a polymeric water-soluble biodegradable material which is formed by the mutual reaction of polyvinyl alcohol and / or polyvinyl alcohol. a partially saponified polyvinyl acetate having a degree of hydrolysis of 70 to 99.5% and a viscosity of 4% aqueous solution at 20 ° C of 3 to 80 mPas and a natural oligomer with a relative average molecular weight of 3000 to 30000, with a nitrogen content of 2 to 16% by weight; prepared by hydrolysis of proteins, e.g. collagen according to the process described in CZ 280655. The material according to the invention can be prepared by reacting both components in an aqueous solution without heating or at elevated temperature and subsequent evaporation of water to form a polymer which can be further mixed with processing additives and fillers and subsequently processed which are commonly known for other polymers (injection molding, extrusion, blow molding, molding, etc.). The new material may also be formed in the melt by thermo-mechanical stress on the mechanical mixture of the two ingredients with the processing ingredients in an extruder with a compression ratio of 1: 2 to 1: 4 and an L / D ratio greater than 10. This produces a homogeneous melt of the new material. which can be directly formed at the outlet of the extruder into the final product (eg by extrusion to profiles, pipes, hoses - blowing on foils - injection molding to various moldings, etc.) or granulated and the resulting granulate used in another technological operation (eg pressing) .

A material having a natural oligomeric content of polyvinyl alcohol of from 1 to 99% can be prepared by both processes, with materials having a natural oligomer content of from 1 to 50% being more preferably prepared from dry blends in an extruder and materials containing an oligomeric component of 50 to 99% by weight. it is preferable to prepare in aqueous solution followed by evaporation of water.

The advantage of the material and the process for its preparation according to the invention is that it has excellent water solubility throughout the above-mentioned composition range, even at reduced temperatures, characterized by a much better biodegradability as pure polyvinyl alcohol or its modifications according to known solutions.

Materials prepared from mixtures having a natural oligomer content of from 1 to 40% by weight, preferably from 3 to 30% by weight, most preferably from 5 to 25% by weight. They are particularly suitable for the production of environmentally water-soluble biodegradable packaging films by blow molding, and the films of the invention have better mechanical properties, better solubility in cold water, much better biodegradability compared to the known polyvinyl alcohol-based film production materials. In addition, these films retain good mechanical properties even at reduced air humidity. These materials are particularly suitable due to the presence of organically bound

286 nitrogen for agricultural applications (packaging of fertilizers, plant protection agents, but in particular for strip seed packing) where they act as a nitrogen fertilizer donor.

Materials prepared from mixtures with a natural oligomer content exceeding 50% by weight. they are particularly suitable for the production of ecological adhesives of various kinds as additives to polymer and rubber mixtures, cements, plasters and as carriers of biologically active substances, e.g. in spray mixtures in agriculture and forestry and the like.

DETAILED DESCRIPTION OF THE INVENTION

Examples 1 to 5

Dry polyvinyl alcohol (PVA) mixtures, respectively, were prepared. partially saponified polyvinyl acetate, modified for thermoplastic treatment by the addition of glycerol as a plasticiser with a natural oligomer with a relative average molar mass of 12000, containing nitrogen

11.8% by weight, according to the procedures as well as the physicochemical and mechanical parameters presented in Table 1a.

Table la

no. Example % hydrolysis of PVA Viscosity of 4% PVA solution [mPas] glycerol content in PVA [wt%] oligomer content in mixture [wt%] Example 1 88 5 12 8 example 2 88 8 15 10 example 3 98 20 20 5 example 4 88 5 15 25 example 5 98 10 12 15

The blends of Examples 1-5 were prepared by blowing the film under the conditions of Table 1b.

Table 1b

no. Example L / D ratio extruder compression ratio foil thickness Example 1 25 1: 2 0,020 Example 2 25 1: 3 0,030 Example 3 30 1: 2 0,030 Example 4 28 1: 4 0,040 Example 5 30 1: 3 0,020

The prepared films had the properties listed in Table 1c.

Table lc

S. example Solubility in water at 10 ° C [• 1 water solubility | Tensile strength [MPa] Ductility [%] Biododegradability [%] 20 ° C 60 ° C Example 1 100 60 - 38 250 16 Example 2 250 120 - 35 200 21 Example 3 - - 60 40 150 10 Example 4 80 20 - 35 270 55 práddad 5 - - 35 37 200 32 PVA 1 230 170 - 37 150 3 PVA 2 300 180 - 35 150 5 PVA 3 - 60 38 100 2 PVA 4 - - 90 41 110 2

PVA films 1 to PVA 4 were prepared from PVA without the addition of an oligomer as reference samples to the films of Examples 1 to 5 as follows:

PVA 1 - to Examples 1 and 4, PVA 2 - to Example 2, PVA 3 - to Example 5 and PVA 4 - to Example 3.

The biodegradability expressed in% was determined respirometrically by a simulated soil incubation test: [(CO ₂ ) _raorka - (CO ₂ ) blank / TI1CO2 "orkaj"

Examples 6 to 8

Proceeding as in Example 1, only 5% of another natural polymeric component of hydrophobized starch, hydroxyethylcellulose and hydrolyzing lignin was added to the composition. The blends were prepared by blowing the film under the conditions set forth in Table 2a.

Table 2a

no. Example % component added 5 wt. ratio L / D extruder compression ratio foil thickness (mm) example 6 starch 25 1: 2 0,035 example 7 hydroxyethyl 25 1: 2 0,030 example 8 hydrolysis lignin 25 1: 2 0,040

The prepared films had the properties listed in Table 2b.

Table 2b

no. Example solubility in water at 10 ° C [si water solubility [s] at 20 ° C Tensile strength [MPa] Ductility 1%) Biodegradability [%] example 6 80 50 35 200 27 example 7 75 50 35 210 22 example 8 80 55 30 180 ¹⁹

Example 9

A dry blend of polyvinyl alcohol having a degree of hydrolysis of 88%, a viscosity of 4% of a 10 mPas solution and a partially saponified polyvinyl acetate with a degree of hydrolysis of 72.5 mol%, a polymerization degree of 700 and a viscosity of 4% of a 6.7 mPas solution was prepared. % of a partially saponified polyvinyl alcohol in a 1: 1 weight ratio of both polymers, adapted for thermoplastic treatment by the addition of 15 wt. % of ethylene glycol and 5 wt. polyethylene glycol 400 as a softening additive, with a natural oligomer having a relative average molecular weight of 12000, with a nitrogen content of 11.8% by weight, according to a process in which the L / D = 25 and the extrusion compression ratio of 1: 3 were prepared, 0,30 mm. The film had similar mechanical properties to the films prepared in Examples 1 to 5, the difference being in lower water solubility, which was 650 s at 10 ° C and 500 s at 20 ° C. The biodegradability of the films has changed only slightly.

Example 10

A 16 mm tape was made from the film prepared according to Example 1, in which radish seeds having a laboratory germination of 95% were placed at even intervals of 2 cm. After planting the seeds, the germination of the seeds was maintained at 95%, but seed emerging in the foil strips of Example 1 was accelerated by one day, more balanced, the plants were in better health condition and more evenly developed. After 14 days of vegetation, the mass of the aerial part of the plants was se

286 names sown in strips 14% larger than the mass of plants from loose seed.

Example 11

An aqueous solution of polyvinyl alcohol having a degree of hydrolysis of 88% and a viscosity of 4% of 8 mPas solution was prepared, which was mixed with a natural oligomer solution having a relative average molecular weight of 20000, with a nitrogen content of 13.5% by weight. such that the solids content of the solution was 40%, the polyvinyl alcohol to oligomer ratio being 1: 3. The prepared solution was heated to 80 ° C with stirring for 1 hour, then cooled and the resulting polymeric material was dried from the solution by spraying the solution through a nozzle into a stream of hot air. The prepared polymer was in the form of a fine powder. The prepared powder was subjected to a biodegradability test of 80%.

Example 12

An aqueous solution of polyvinyl alcohol, respectively, was prepared. % of a partially saponified polyvinyl acetate having a degree of hydrolysis of 88% and a viscosity of 4% of a 5 mPas solution mixed with a natural oligomer solution having a relative average molecular weight of 10,000, a nitrogen content of 11.5% by weight; such that the solids content of the solution was 20%, the polyvinyl alcohol to oligomer ratio being 7: 3. The resulting solution was heated to 80 ° C with stirring for 1 hour, then cooled. The film was then made from the viscous solution by casting. The film had the following properties: tensile strength - 42 MPa; elongation - 190%; water solubility at 10 ° C - 95 s; water solubility at 20 ° C to 50 s; biodegradability - 52%.

Example 13

Powdered PVA was added to a 30% natural oligomer solution in an amount such that the natural oligomer to pVA ratio was 9: 1. After drying the solution in a fluidized bed dryer, powdered material was obtained which was homogeneously mixed with gypsum in a weight ratio of 5 parts powder. 100 parts plaster. The resulting product was characterized by improved adhesion to substrates, uniform cure and extended cure time.

Example 14

The procedure was as in Example 9, except that the resultant ratio of the natural oligomer to PVA constituents was 19: 1. The solution was further diluted 1: 10 with water and admixed as a fungicide Ridomil 48 WP to a concentration of 0 , 25%. Such a preparation was applied as a vine spray in June. Said composition, compared to a spray prepared with only water, increased the adhesive properties of the spray, which resulted in the formation of a uniform film of the composition on the leaves. Compared to the control (spraying applied only with water as solvent), the protective effect lasted 7 days longer.

Example 15

Proceeding as in Example 9, only the resulting ratio of natural oligomer to PVA components was 1: 1. The viscous solution was diluted with an amount of water to give a total dry matter content of 10%, and such a solution was mixed with a starch adhesive solution for seed coating process. in a 1: 1 ratio. This preparation was applied sequentially by spraying onto sugar beet seed in the technological process of seed coating at a temperature of 20 ° C, while maintaining good seed coating quality. Subsequently, the vegetation tests showed a faster and more balanced germination of the plants derived from the coated seeds with the preparation used, compared to the plants which originated from the normally coated seeds. After 28 days of vegetation, the seeds of the seeds coated with the preparation according to the invention had a weight of the above-ground part of the plants 12% greater than the plants of the briefly coated seed.

Industrial usability

Polymeric water-soluble biodegradable material resulting from the interaction of polyvinyl alcohol and a natural oligomer with a content of up to 50% by weight. is particularly suitable for the production of environmentally water-soluble biodegradable packaging films by blowing, but also fibers, shaped articles for various applications or as an additive serving as a carrier or encapsulant. Materials with a natural oligomer content above 50% by weight. they are particularly suitable for the production of ecological adhesives of various kinds as additives for polymer and rubber mixtures, cements, plasters and as carriers of biologically active substances, e.g. in spray mixtures in agriculture and forestry and the like.

Claims (7)

PATENT CLAIMS Polymeric water-soluble biodegradable material based on a synthetic polymer and a natural oligomer to polymer or mixtures thereof with fillers and / or biologically active compounds, characterized in that the synthetic polymer comprises polyvinyl alcohol and / or partially saponified polyvinyl acetate having a degree of hydrolysis of 70 to 99.5 % mol and the viscosity of the aqueous solution and / or sol at 20 ° C of 3 to 80 mPas and the natural nitrogen-containing oligomer to polymer in an amount of 1 to 99 wt. % having a relative average molar mass of from 3000 to 30000 with a nitrogen content of from 2 to 16% by weight; or mixtures thereof with processing aids and fillers and / or biologically active compounds in an amount of from 85 to 5 wt. Water-soluble biodegradable material according to claim 1, characterized in that the natural oligomer to polymer consists of amino acid to polyamino acid oligomers such as partially hydrolysed or partially saponified collagen, sodium or ammonium oligomeric amino acid salts. Water-soluble biodegradable material according to claim 1 and 2, characterized in that the filler comprises polyvinyl alcohol plasticizers such as glycerol, ethylene glycol, polyethylene glycol and organic materials such as cellulose fibers, wood flour, natural or modified celluloses, starches, hemicelluloses and lignins. Water-soluble biodegradable material according to claims 1 to 3, characterized in that the biologically active substances are selected from pesticides, herbicides, insecticides, fongicides, growth regulators and fertilizers. Process for the preparation of a polymeric water-soluble biodegradable material according to claims 1 to 4, characterized in that polyvinyl alcohol and / or partially saponified polyvinyl acetate with a degree of hydrolysis of 70 to 99.5 mol% and a viscosity of the aqueous solution and / or sol with concentration of 4 wt. at a temperature of 20 ° C of 3 to 80 mPas of a natural nitrogen-containing oligomer to polymer having a relative average molecular weight of from 3000 to 30000, a nitrogen content of from 2 to 16% by weight, or mixtures thereof with fillers and / or bio4 logically active compounds from 85 to 5% by weight, at a temperature of 0 to 270 ° C, wherein the process takes place in at least one of the following forms: aqueous solution, sol, dispersion or melt mixture. Method for preparing a polymeric water-soluble biodegradable material according to claim 5, characterized in that after formulating the mixture of the components in solid form, it is melted to form a homogeneous melt which can be directly formed into a final product such as water-soluble films, filaments or water-soluble melt. granulate. Process for preparing a polymeric water-soluble biodegradable material according to claims 5 and 6, characterized in that the components of the biodegradable material, when formulated and reacted in the form of an aqueous solution, sol or dispersion, form a directly applicable system or are dried to form a fine, easy to apply material.