KR930010205B1 - Process for producting shaped articles from vegetable particulate materials - Google Patents

Abstract

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Description

Manufacturing method of form goods from plant particulate matter

1 is a graph showing the tensile strength test for the amount of variation of prepolymer C of the sheet of the present invention.

2 is a graph showing the tensile strength test for the amount of change of water in the sheet of the present invention.

3 is a graph showing the effect on the tensile strength according to the particle size distribution of the sawdust of the sheet of the present invention.

4 is a graph showing the effect on the tensile strength according to the bark fiber content of the sheet of the present invention.

5 is a graph showing the tensile strength test for the content of polyvinylacetate (PVAc) emulsion of the sheet of the present invention.

6 is a graph showing the tensile strength test for the content of the ethylene-vinyl acetate copolymer (EVA) emulsion of the sheet of the present invention.

7 is a graph showing the tensile strength test for the content of ethylene-vinylacetate vinyl beulate copolymer of the sheet of the present invention.

The present invention relates to a method for producing a flexible sheet or other form article from plant particulate matter.

Japanese Patent Application No. 106932/1984 describes sheets of plant particulate matter bound together with binder resins by rolling or otherwise shaping the resulting mass under pressure if the particles are covered with isocyanate terminated urethane prepolymers or polyisocyanate compounds; It specifies how to make other shaped articles. The urethane prepolymer or polyisocyanate compound applied to the particles crosslinks the individual particles together through a chemical reaction with the atmospheric moisture of the isocyanate groups or with the active sites of the particles. This method requires a relatively large amount of binder prepolymer or compound and is not suitable for mass production of inexpensive articles such as pollen. Moreover, the relatively long curing time and blocking for the molds prevents the method from being applied to the mass production of shaped articles on a continuous scale.

The method of the invention is distinguished from the prior art in providing a flexible sheet or article in a cost effective manner.

In summary, the present invention is as follows.

According to the present invention, urethane pres having a plurality of terminal free isocyanate groups formed by reacting an excess polyisocyanate with at least two terminal hydroxyl groups per molecule and a polyoxyalkylene polyol having an oxyethylene unit content of 10 to 90% by weight. An aqueous mixture comprising a polymer is applied to the plant particulate material, which contains excess water, followed by shaping the resulting mass and curing and drying the product. A method of making an article is provided. The aqueous mixture of urethane prepolymers may optionally comprise an inert binder polymer.

The resulting article can be hardened under heat pressurization to enhance rigidity.

Preferred specific examples are as follows.

The urethane prepolymers used in the present invention can be prepared by reacting an excess polyisocyanate compound with a polyoxyalkylene polyol having at least two terminal hydroxyl groups per molecule and an oxyethylene unit content of 10 to 90% by weight, as is known. Can be. Polyol compounds can in turn be prepared by addition reaction of an alkylene oxide mixture with a starting active hydrogen compound. Examples of starting active hydrogen compounds that should have at least two active hydrogens per molecule include ethylene glycol, propylene glycol, hydroquinone, bisphenol A, 1,6-hexanediol, neopentylglycol, glycerin, trimethylol propane, 1,2,6 -Hexanetriol, pentaerythritol, alpha-methylglycoside, sorbitol, sucrose, castor oil, ethylenediamine, diethylenetriamine, piperazine, methylamine, n-butylamine, aniline, xylylenediamine and the like do. Examples of ethylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, and the like. The proportion of ethylene oxide in the ethylene oxide mixture should be 10 to 90% by weight. The addition reaction can be carried out by air. The resulting polyether polyols preferably have a molecular weight greater than 1,000.

The oxyethylene units present in each polyoxyalkylene chain can form tandem or block copolymers. If the oxyethylene unit content is greater than 90%, for example 100%, the polyether polyols often occur as a solid at ambient temperature or the urethane prepolymer derived therefrom will cure too quickly to a solid state. Conversely, if less than 10% of the oxyethylene content in the polyether polyox, the urethane prepolymer derived therefrom tends to be less hydrophilic than desired.

Examples of polyisocyanate mixtures include toluylene diisocyanate (purified or crude TDI), disphenylmethane diisocyanate (MDI), polyethylene polyphenylisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, nattalene diisocyanate, iso Poron diisocyanate, and mixtures thereof. Urethane prepolymers with terminal free isocyanate groups can be prepared by reacting a polyisocyanate compound with a polyether polyol at a NOC / OH equivalent ratio of 1.5 to 100, preferably 2 to 20. The resulting prepolymer can optionally be combined with a binder polymer. It can be easily dissolved or dispersed in a large excess of water to form a binder liquid for binding plant particulates. Water acts as a chain extender for urethane prepolymers.

The binder liquid may optionally comprise a solution or emulsion of the inert binder polymer. Examples of water soluble binder polymers that can be used include polyvinyl alcohol, polyacrylic acid, polyacrylamide, water soluble maleic acid copolymers and the like. Examples of emulsions of binder polymers include natural or synthetic rubber latexes such as natural rubber, SBR, chloroprene rubber, acrylonitrile-butadiene rubber, acrylate-butadiene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, and the like. Polyvinylacetate, polyvinylchloride, polyvinylidene chloride, vinyl chloride-vinylacetate copolymer, ethylene-vinylacetate copolymer, polyacrylate, aminoplast and phenolic resin can also be used.

The proportion of water in the binder liquid is preferably at least equal to 50 times but less than the combined solids content of the urethane prepolymer and the inert binder resin.

Examples of plant particulates include sawdust, wood chips, cork powder, rice bran, rice flour, soy flour, rice or other grain husks, straw, and finely divided bark. It is not limited to them.

In carrying out the process of the invention, the plant particles are first applied in this way by spraying the binder solution. The resulting form and compound were soon spread on the mat to form a sheet and allowed to cure at room or room temperature and dried. Alternatively, the compound may be formed into a desired form by molding under pressure. Instead of applying the premixed binder liquid, the plant particulate material is dampened with a large amount of water and then mixed with the remaining ingredients.

The forming compound may comprise other conventional additives such as solvents, plasticizers, defoamers, surfactants, colorants, fillers, curing catalysts and the like.

The resulting sheet or other shaped article can be hardened by pressing under heating for further strength properties. This secondary processing is preferably carried out at a pressure of 2 to 200 kg / cm ² , more preferably of 10 to 60 kg / cm ² and at a temperature of 70 to 200 ° C., more preferably 100 to 170 ° C.

The present invention provides a method for producing expensive sheets and other shaped articles having excellent solubility and other stiffness in a cost effective manner starting from waste or valuable materials.

The following examples are provided for illustrative purposes only. All parts and percentages are by weight unless otherwise indicated.

Example 1

Preparation of Urethane Prepolymer

The urethane prepolymers A, B and C shown in Table 1 were prepared by reacting the polyalkylene polyols listed in Table 1 with polyisocyanates and diluting them to 70% concentration with ethyl acetate.

Polyalkylene polyols can be synthesized by addition reaction of a mixture of ethylene oxide (EO) and propylene oxide (PO) with a starting compound to form a random copolymer.

TABLE 1

Example 2

100 parts of the urethane prepolymer solution A of Example 1 were mixed with 300 parts of water. The mixture was sprayed in 20 seconds onto 50 parts of sawdust having a water content of 15%. The resulting mass was soon spread on a plate about 8 mm thick and left to cure at 22 ° C. Curing time was about 3 minutes after spraying. The resulting sheet was dried in a drier at 80 ° C. for 3 hours to obtain a flexible sheet having a thickness of about 8 mm. This sheet can be used as a billboard, flexible floor covering, etc.

Example 3

10 parts of the 1: 1 mixture of the urethane prepolymers A and B of Example 1 were mixed with 357 parts of water. The mixture was sprayed onto sawdust as used in Example 2 at a rate of 514 parts per 100 parts of sawdust. After spraying, the sawdust was immediately shaped into sheets having a thickness of about 1.5 mm, left to cure at 22 ° C. and dried to obtain a thin flexible sheet. This sheet can be used as a packaging material for steel pipes and the like.

Example 4

Sawdust of juniper and cypress from the mill with a water content of 5.9%, 60 mesh barrels 20%, 60-52 mesh barrels 6.7%, 52-48 mesh barrels 5.3% and 48 mesh barrels 68% Used. 50 parts of the sawdust, 250 parts of water and the prepolymer solution C of Example 1 were used in varying amounts of 4, 5, 6, 7, 10, 15 and 20 parts respectively to make sheets and tension as in the previous example Strength was tested. The results obtained are shown in FIG. Tensile strength was approximately proportional to the amount of urethane prepolymer.

Example 5

Sheets were made as in Example 4 and tested for tensile strength using 50 parts of sawdust, 10 parts of urethane prepolymer solution C, and water in varying amounts of 150, 200, 250, 300 and 400 parts, respectively. The results obtained are shown in FIG. The data indicate that the tensile strength decreases if the optimal range of water is between 200 and 300 parts per 10 parts of urethane prepolymer solution C and the amount of water is outside this range.

Example 6

The sheet was made as in Example 4 using 50 parts of sawdust, 250 parts of water, 7 parts of urethane prepolymer solution C (series A) or 10 parts (series B). Sawdust was used without sieving in (1) times. In (2) and (3), 60 mesh and 40 mesh passes were used, respectively. The results obtained are shown in FIG. The data indicate that the particle size distribution of sawdust has little effect on tensile strength. However, it may be desirable for the sawdust to have a relatively large particle size distribution, as the sheets made from 40 mesh pass through exhibited reduced tensile strength.

Example 7

50 parts of sawdust, 7 parts of urethane prepolymer solution C, and 250 parts of water were used to make the sheet as in Example 4, but sawdust was varied with short fibers (0.5-2 cm) or long fibers (3.0-6.0 cm). Mixed. The obtained result is shown in FIG. Short fibers decreased with increasing proportions and had no effect on tensile strength.

Long fibers have a significant effect on strength, but the flow of form and compound decreases too much to produce sheets at higher rates.

[Example 8]

Forms and compounds were prepared by spraying 5 parts of solution C and 250 parts of water of the urethane prepolymer of Example 1 onto 50 parts of sawdust used in Example 4. The compound was immediately press-molded in a mold for 2 minutes at a pressure of 45 kg / cm ² , removed from the mold and dried to obtain a flower pot having a length of 50 mm, a width of 150 mm, a depth of 100 mm and a wall thickness of 10 mm. This pollen was impermeable to water and permeable to air. Therefore, this pot is more suitable for growing plants than conventional plastic powder.

Example 9

355 parts of the aqueous mixture of the urethane prepolymer used in Example 8 were sprayed onto 100 parts of a powder mixture of sawdust, rice bran, rice flour, soy flour and poultry droppings. The resulting compound was immediately press molded at a pressure of 35 kg / cm ² , removed from the mold and dried to obtain a pollen. This pollen is particularly useful for agricultural purposes because it can be decomposed and fertilized by the action of water in the soil when the shoots grown in this pot are transferred.

[Example 10]

100 parts of a mixture of oak top bar (Q.rerrata, Q.acutissima, etc.) containing a small amount of shiitake mushroom mycelium (Shiitake hypha: Lentinus edodes) of the urethane prepolymer solution C of Example 1 and 5 parts of Spray-coated to 375 parts. The resulting compound was press-molded in a mold for 2 minutes at a pressure of 42 kg / cm ² to produce a bar 150 cm in length and 10 × 10 cm ² square area. The formed bar was removed from the mold and then dried. This bar can be used to cultivate shiitake mushrooms as a content for natural bed logs.

Example 11

The urethane prepolymer solution C of Example 1 comprising 50 parts of sawdust used in Example 4 in varying amounts of polyvinylacetate (PVAc) emulsion (41% nonvolatile) in 0, 1, 5, 7 and 10 parts respectively. Spray coating with a mixture of 7 parts and 250 parts of water. Sheets were made from each compound, dried and tested for tensile strength. The results obtained are shown in FIG. The data indicate that tensile strength can be increased proportionally to the amount of polyvinylacetate emulsion. However, the sheets are harder and less flexible with increasing polyvinylacetate emulsion.

Example 12

The method of Example 11 was repeated but the polyvinylacetate emulsion was replaced with an ethylene-vinylacetate copolymer (EVA) emulsion (47% nonvolatile). The results obtained are shown in FIG. The effect of EVA emulsion on tensile strength was not as important as polyvinylacetate emulsion, but the flexibility was well maintained even at higher proportions of EVA emulsion.

Example 13

The method of Example 11 was repeated but the polyvinyl acetate emulsion was replaced with an ethylene-vinylacetate-versatate copolymer (50% nonvolatile) emulsion.

The results obtained are shown in FIG. The additive effect of ethylene-vinylacetate-vinyl valtate copolymer emulsion on tensile strength was between PVAc and EVA emulsion.

Example 14

The two formed sheets obtained in Example 4 were pressed for 5 minutes at 120 ° C. at a pressure of 50 kg / cm ^{2 with} a coating amount of 20 and 30% sawdust urethane prepolymer solution C, respectively. Deogap initial tensile strength of 530g / cm ^2, and 1,100g / cm ² was increased in each 1,050g / cm ^2, and 2,020g / cm ^2.

Example 15

The two formed sheets obtained in Example 13 containing 5% and 10% ethylene-vinylacetate-vinyl berate acetate emulsion respectively were pressed at 120 ° C. at a pressure of 150 kg / cm ² for 5 minutes.

The initial tensile strength of 670g / cm ² to 875g / cm ² was increased by each 1,310g / cm ^2, and 1,595g / cm ^2.

[Example 16]

15 parts of the urethane prepolymer solution A of Example 1 were mixed with 150 parts of water. The mixture was immediately mixed well with 100 parts of rice husk within 20 seconds. The resulting mass was spread on a mold frame to a thickness of about 20 mm and allowed to cure at 22 ° C. Curing was completed within 3 minutes after mixing the prepolymer with water.

After standing for 24 hours, the resulting sheet was pressed for 1 minute at a pressure of 20 kg / cm ² at 100 ° C. to obtain an elastic sheet having a thickness of 10 mm, a density of 0.50 g / cm ³ , and a bending strength of 28 kg / cm ² .

Claims (10)

An aqueous mixture comprising a urethane prepolymer having a plurality of terminal free isocyanate groups formed by reacting excess polyisocyanate with at least two terminal hydroxyl groups per molecule and a polyalkylenepolyol having an oxyethylene unit content of 10 to 90% by weight. This mixture contains a large amount of water, which comprises applying it to the plant particulate material, shaping the resulting mass, and curing and drying the formed article. Manufacturing method. The method of claim 1, wherein the amount of the urethane prepolymer is 8 to 40% by weight of the plant particulate material. 2. A process according to claim 1 wherein the amount of water in said aqueous mixture of urethane prepolymer is at least equal to, but less than 50 times, the solids content of said aqueous mixture. The method of claim 1, wherein the polyoxyalkylene polyol and the polyisocyanate are reacted at a NOC / OH equivalent ratio of 1.5 to 100. The process of claim 1 wherein said aqueous mixture of urethane prepolymers additionally comprises an inert binder polymer. The method of claim 5, wherein the binder polymer is a polyvinylacetate, ethylene-vinylacetate copolymer or ethylene-vinylacetate-vinyl beolate copolymer. The method according to claim 1, wherein the plant particulate material is sawdust, wood chips, cork powder, rice bran, salt powder, soy flour, rice or other grain shells, straw or finely divided bark. The method of claim 1 wherein said shaping step comprises compression molding. The method according to claim 1, further comprising the step of solidifying the resultant form article under heating and pressurization. 10. The method according to claim 9, wherein the step of hardening is performed at a temperature of 70 to 200 ° C and a pressure of 2 to 200 kg / cm ² .

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