FR2608961A1 - PROCESS FOR THE MANUFACTURE OF SHAPED ARTICLES FROM MATERIALS IN VEGETABLE PARTICLES - Google Patents

Abstract

PROCESS FOR THE PRODUCTION OF LEAVES OR OTHER SHAPED ARTICLES. THE PROCESS CONSISTS OF APPLYING A SOLUTION OR DISPERSION OF A URETHANE PREPOLYMER OF A HYDROPHILIC NATURE IN A LARGE EXCESS OF WATER POSSIBLY CONTAINING AN INERT BONDING POLYMER, ON PARTICLES OF PLANT MATERIALS, TO FORM THE MASS, ALLOW TO HARDEN AND DRY SHAPED ARTICLES.

Description

PROCESS FOR THE MANUFACTURE OF SHAPED ARTICLES FROM

OF MATERIALS IN PLANT PARTICLES

  The present invention relates to a process for the manufacture of flexible sheets or other articles of

  form from matter in vegetable particles.

  Japanese patent application (Kokai) No. 106932/1984 describes a process for the manufacture of sheets or other shaped articles of vegetable matter in particles bonded together by means of a resin binder, by coating

  particles with urethane prepolymers with iso- groups

  cyanate terminals or with polyisocyanate compounds, then cylindrical or otherwise shaped the resulting mass, under pressure. The urethane prepolymer

  or the polyisocyanate compound applied to the particles

  gender mutual crosslinking of individual particles-

  them, by chemical reaction of the isocyanate group with humi-

  atmospheric or with active sites presented by

  the particles. This process requires relative quantities-

  large prepolymer or binder compound and is not suitable for mass production of inexpensive items, such as planting pots. In

  furthermore, the relatively long curing time and immo-

  bilisation in the mold prevent the application of the process to the mass production of shaped articles on a

base continues.

  The subject of the present invention is a method which makes it possible to obtain flexible sheets or other articles,

economically.

  According to the present invention, a process for manufacturing sheets or other articles is obtained.

  form, including the operations of application to the par-

  ticles of plant material of an aqueous mixture containing a urethane prepolymer which has a plurality of free terminal isocyanate groups, formed by reaction of an excess

  of a polyisocyanate with a polyoxyalkylene polyol comprising

  both at least two terminal hydroxyl groups per molecule and a content of oxyethylene units of 10 to 90% by weight, this mixture containing a large excess of water; shaping the resulting mass; hardening and drying

  resulting articles. The aqueous mixture of said prepolymer-

  urethane re may optionally contain an inert polymeric binder

  you. The resulting article can further be compacted, by application of heat and pressure, to improve

  mechanical strength characteristics.

  The urethane prepolymer used in the present invention can be prepared in a known manner, by reaction

  of an excess of polyisocyanate type compound with a poly-

  oxyalkylene polyol having at least two hydro-

  xyl terminals per molecule and having an oxyethy-

  lene from 10 to 90% by weight. The polyol-type compound can itself be prepared by the addition reaction of a mixture of alkylene oxide with a hydrogen starting compound

  active. As examples of starting compounds with hydrogen

  tif, which must have at least two atoms of hydrogen

  tif per molecule, there may be mentioned: ethylene glycol, propylene glycol, hydroquinone, bisphenol A, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, alphamethylglycoside, sorbitol, sucrose,

  castor oil, ethylenediamine, diethylenetriamine, pipera-

  zine, methylamine, n-butylamine, aniline, xylylenediamine and others. As examples of alkylene oxides, mention may be made of: ethylene oxide, propylene oxide, butylene oxide,

  styrene oxide, tetrahydrofuran and the like. The proportion

  tion of ethylene oxide in the mixture of alkyl oxides

  The weight should be 10 to 90% by weight. The addition reaction

  can be carried out in a known manner. Poly- polyethers

  ols resulting have preferably a molecular weight su-

  less than 1000. The oxyethylene units present in

  each polyoxyalkylene chain can constitute a co-

  statistical lymer or a block copolymer. If the content of oxyethylene units is greater than 90%, for example%, polyether polyols are often present in

  solid form at room temperature, or prepoly-

  urethane mothers that derive from it harden too quickly to rigid states. Conversely, if the content of oxyethylene units in the polyether polyols is less than 10%, the urethane prepolymers derived therefrom tend to be

  less hydrophilic than would be desirable.

  As examples of compounds of polyisocyanate type, there may be mentioned: toluylènediisocyanate (purified or crude TDI),

  disphenylmethanediisocyanate (MDI), polyethylene polyphenyli-

  socyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, and mixtures thereof. The urethane prepolymer terminated with free isocyanate groups can be prepared by reacting the polyisocyanate compound and the polyether polyol in an NCO / OH ratio.

  equivalent from 1.5 to 100 and preferably from 2 to 20. The pre-

  resulting polymer can be easily dissolved or dispersed in a large excess of water, possibly at the same time

  than a polymer type binder, to constitute a li-

  what is the bond of vegetable matter in particles. The water

  acts as a chain extender for the urethane prepolymer.

  The liquid binder can optionally contain a solution.

  tion or an emulsion of inert binding polymers. As

  examples of water soluble bonding polymers used

  sands, there may be mentioned: polyvinyl alcohol, poly-

  acrylic, polyacrylamide, water-soluble maleic acid copolymers, etc. As examples of emulsions of binding polymers, mention may be made of natural or synthetic rubber latexes such as natural rubber, SBR, chloroprene rubber, acrylonitrile-butadiene rubber,

  acrylate-butadiene rubber, isoprene rubber, rubber

  butyl choux, ethylene-propylene rubber and the like.

  Emulsions of other polymers can also be used.

  bonding res such as polyvinyl acetate, chloride

  polyvinyl, polyvinylidene chloride, chlo- copolymer

  vinyl rure-vinyl acetate, ethylene copolymer-

  vinyl acetate, polyacrylate, aminoplast and resins

phenolic.

  The proportion of water in the liquid binder is preferably at least equal to the amount of solid matter

  combination of urethane prepolymer and bonding resin

  its inert, but less than 50 times this amount.

  As examples of vegetable matter in particular

  these include, but are not limited to: sawdust, wood fragments, cork powder, rice bran, oilseed meal, soybean meal, husk of rice or other cereals, straw,

  finely divided bark and others.

  In carrying out the process according to the present invention, the binder solution is first applied

  particles of plant matter, for example by spraying

  station. The resulting shaping compound is immediately spread on a carpet to form a sheet which is allowed to cure at room temperature or higher and which

  dried. Alternatively, this compound can be brought into a form

  sirée, by pressure molding. Instead of applying the premixed liquid binder, the plant material particles can be wetted with a large amount of water, then

  mix them with the other components.

  The shaping compound may contain other usual additives, such as solvents, plasticizers, agents

  anti-foaming, surfactants, dyes, fillers,

plug talysers and the like.

  We can compact sheets or other items

  resulting form, by hot pressing to increase

  core mechanical strength characteristics. This treat-

  The secondary ment is preferably carried out under a pressure of 200 to 10,000 kPa, and preferably from 1000 to 6000 kPa, and at a temperature of 70 to 200 C, and preferably from 100 to C. The present invention provides a process for the manufacture of sheets and other shaped articles having

  excellent flexibility and other qualities of resistance

  mechanical tance, from waste or lesser materials

value, economically.

  The examples below are given by way of illustration.

  lustration of the invention only. All parties

  and percentages are by weight, unless otherwise indicated

to milk.

EXAMPLE 1

  Preparation of urethane prepolymer Solutions of urethane prepolymer are prepared

  A, B and C, indicated in Table 1 (Page 12), by reaction

  tion of polyalkylene polyols and polyisocyanates listed in Table 1 and diluted with ethyl acetate to a concentration of 70%. The synthesis of polyalkylene polyols is carried out by the addition reaction of an oxide mixture

  ethylene (OE) and propylene oxide (OP) with a compound

  starting point to form a random copolymer.

EXAMPLE 2

  10 parts of solution A of prepolymer are mixed

  urethane of Example 1, with 300 parts of water. We sprayed

  mix the mixture on 50 parts of sawdust with a moisture content of 15%, in 20 seconds. The resulting mass is immediately spread out on a flat plate, to a thickness of approximately 8 mm, and it is left to harden at 22 C.

  curing is approximately 3 minutes after spraying.

  The resulting sheet is dried in a dryer at 80 ° C.

  within three hours, to obtain a flexible sheet of

  thickness of about 10 mm. This sheet can be used

  as a display panel, elastic floor covering, etc.

EXAMPLE 3

  10 parts of a 1: 1 mixture of the prepo-

  urethane A and B lymers of Example 1, with 357 parts of water. The mixture is sprayed on the same sawdust as in Example 2, in a ratio of 514 parts per 100 parts of sawdust. After spraying, the sawdust is immediately formed into a sheet with a thickness of about 1.5 mm that allowed to harden at 22 C and dried to obtain a

  thin flexible sheet. You can use this sheet

  packaging material for steel tubes and the like.

EXAMPLE 4

  We use cedar sawdust and cypress

  from sawmills, which has a moisture content of 5.9% and

  a particle size distribution of 20% passage to the mail-

  the of 0.246 mm, 6.7% of passage between 0.246 mm and 0.270 mm, 5.3% of passage between 0.270 and 0.295 mm and 68% of mesh retention of 0.295 mm. Sheets are prepared as in the previous examples, using 50 parts of this

  sawdust, 250 parts of water and a variable amount of solu-

  tion of prepolymer C of Example 1, 4, 5, 6, 7, 10, 15 and 20 parts respectively, and tests are carried out on the tensile strength of these sheets. The results obtained are illustrated in Figure 1. The tensile strength is substantially proportional to the amount of

urethane prepolymer.

EXAMPLE 5

  Sheets are prepared as in Example 4 using 50 parts of sawdust, 10 parts of urethane prepolymer solution C and an amount of water variable to 150,200, 250,300 and 400 parts, respectively and

  measures the tensile strength of the sheets. The results

  The states obtained are illustrated in Figure 2. The values show that an optimal range of the quantity of water is

  between 200 and 300 parts for 10 parts of pre-

  urethane polymer C and that the tensile strength

  minue if the amount of water is outside this range.

EXAMPLE 6

  Sheets are prepared as in Example 4, in

  using 50 parts of sawdust, 250 parts of water and 7 parts

  ties (series A) or 10 parts (series B) of prep solution

  urethane lymer C. In test (1), sawdust is used without sieving. In test (2) and test (3), we use

  sawdust retained through a sieve of 0.246 mm mail opening

  le and 0.370 mm respectively. The results obtained are

  shown in Figure 3. These results show that the re-

  particle size distribution of sawdust particles has little effect on tensile strength. However, since the sheet made from the sawdust retained in the 0.370 mm sieve has a reduced tensile strength, it may be preferable that the sawdust has a distribution

  relatively large particle size.

EXAMPLE 7

  Sheets are prepared as in Example 4, using 50 parts of sawdust, 7 parts of urethane prepolymer solution C and 250 parts of water, but the sawdust is mixed with short fibers (0.5-2 cm) or long fibers (3.0-6.0 cm) of cedar bark, in varying proportions. The results obtained are shown in Figure 4. Short fibers have no effect on

  tensile strength, which decreases when the propor-

  tion of fibers increases. Long fibers have a significant effect on the resistance but the fluidity of the compound

  shaping decreases too much for the manufacture of a sheet

  the, for the highest proportions.

EXAMPLE 8

  A shaping or molding compound is prepared

  lage, by spraying a mixture of 5 parts of solu-

  urethane C prepolymer of Example 1 and 250 par-

  water ties on 50 parts of sawdust used in Example 4. This compound is immediately compression molded in

  a mold under a pressure of 45 x 105 Pa for 2 minutes

  you remove it from the mold and dry it to obtain a planting pot with a length of 50 mm, a width

  150 mm, a depth of 100 mm and a thickness of pa-

  10 mm king. This planting pot is waterproof but breathable. Therefore, this pot is better suited for growing plants than the usual plastic pots.

EXAMPLE 9

  355 parts of an aqueous mixture of the urethane prepolymer used in Example 8 are sprayed on 100 parts of a powdery mixture of sawdust, rice bran,

  oilseed meal, soybean meal and poultry droppings.

  The resulting compound is immediately molded by compression.

  sion under a pressure of 35 x 105 Pa, removed from the mold and dried to obtain a planting pot. This pot is suitable

  particularly for agricultural uses since,

  young plants grown in this pot are Apparated

  tees as is, the pot is broken down by the action of water

into the soil and becomes a fertilizer.

EXAMPLE 10

  parts of a mixture of sawdust (Q.

  rerrata, Q. acutissima, etc.) and rice bran containing a small amount of Shiitake hypha (Lentinus edodes)

  are spray coated with 375 parts of a met

  diaper composed of 5 parts of solution of prepolymer of

  Rethane C from Example 1 and 250 parts of water. The resulting compound is compression molded in a mold, into a

  bar having a length of 150 cm and a cross section

  dirty square of 10 x 10 cm2, under a pressure of 42 x 105 Pa for 2 minutes. The formed bar is removed from the mold and then dried. We can use this bar for growing

  of Shiitake, replacing natural logs.

EXAMPLE 11

  parts of the sawdust used in Example 4

  are spray coated with a mixture of 7 parts

  urethane C prepolymer solution ties of the example

  1 and 250 parts of water containing a variable amount of e-

  polyvinyl acetate (PVAc) emulsion with 41% non-material

  volatile, at 0,1,5,7 and 10 parts respectively. We prepare

  re sheets from the respective compounds, they are se-

  che and measure their tensile strength. The results

  The results obtained are illustrated in FIG. 5. These results show that the tensile strength can be improved in proportion to the quantity of polyvinyl acetate emulsion. However, the sheet becomes more rigid and less flexible when the amount of acetate emulsion

of polyvinyl increases.

EXAMPLE 12

  The procedure of Example 11 is repeated, except that the polyvinyl acetate emulsion is replaced by an ethylene-vinyl acetate copolymer emulsion.

  (EVA) at 47% non-volatile matter.

  The results obtained are shown in the figure

  6. The effect of the EVA emulsion on the resistance to traction

  tion is not as sensitive as that of the emulsion of a-

  polyvinyl acetate, but the flexibility is enough

  preserved even for high proportions of EVA emulsion.

EXAMPLE 13

  The procedure of Example 11 is repeated except that the polyvinyl acetate emulsion is replaced by

  an emulsion of an ethylene-vinyl acetate copolymer

  vinyl versatate with 50% non-volatile matter.

  The results obtained are illustrated by the fig-

  re 7. The effect of adding the copolymer emulsion

  ethylene-vinyl acetate-vinyl versatate on the re-

  mechanical resistance is intermediate between those of emulsi-

sions of PVAc and EVA.

EXAMPLE 14

  Two formed sheets are obtained, obtained in Example 4 with an amount of coating of urethane prepolymer solution C of 20% and 30%, respectively, relative to the weight of sawdust, under a pressure of 50 x 105 Pa at 120 C for 5 minutes. The initial values

  tensile strength of 530 hPa and 1100 hPa are increased

  mapped at 1050 hPa and 2020 hPa, respectively.

EXAMPLE 15

  Two formed sheets are pressed, obtained in

  Example 13 by incorporation of an ethylene emulsion

  vinyl acetate-vinyl versatate at 5% and 10% respectively

  under pressure of 150 x 105 Pa at 120 C for minutes. The initial tensile strength values of 670 hPa and 875 hPa are increased to 1310 hPa and 1595

hPa, respectively.

EXAMPLE 16

  15 parts of prepolymer solution are mixed

  urethane A of Example 1 with 150 parts of water. To me-

  diaper is immediately mixed intimately with 100 parts

  rice husk, in 20 seconds. We spread the resulting mass

  te in a molding frame, 20 mm thick

  roughly, and let it harden at 22 C. The setting is finished

  in three minutes after mixing the prepolymer with water.

  After 24 hours of rest, the resulting sheet is pressed under a pressure of 20 x 105 Pa at 100 C for one minute, to obtain a flexible sheet having a

  thickness of 10 mm, a density of 0.50 g / cm3 and a resistance

flexural strength of 28 x 105 Pa.

  It is understood that modifications of detail can be made in the form and the implementation of the method according to the invention, without departing from the scope thereof.

TABLE 1

  Polyalkylene polyol Polyisocyanate Prepolymer Compound of PM Content Number Name Parts Ratio Starting content of atoms in average OE for 100 hydrogen equivaNCO (%) parts of slow active polyalkylè- NCO / OH ne polyol A Glycerin 3 80 7000 TDI 16.0 4 .0 5.0 B Propylene 2 50 4000 MDI 38.5 5.3 7.0 crude glycol C Sorbitol 6 70 8000 MDI 29.2 2.9 5.0 pure ro Co

Claims (10)

Claims   1. Process for manufacturing sheets or the like   shaped articles, characterized in that it consists of   pleating particulate plant materials with an aqueous mixture containing a urethane prepolymer which has a plurality of free terminal isocyanate groups, formed by   reaction of an excess of a polyisocyanate with a polyalkylè-   ne polyol having at least 2 terminal hydroxyl groups. per molecule and a content of oxyethylene units of 10 to 90% by weight, said mixture containing a large excess of water; shaping the resulting mass; to harden and dry the articles formed.   2. Method according to claim 1, characterized   in that the amount of said urethane prepolymer represents   te from 8 to 40% by weight of said vegetable matter in particular cules.   3. Process according to claim 1 or 2, charac-   terized in that the amount of water in said aqueous mixture of urethane prepolymer is at least equal to the amount of solids in said aqueous mixture but less than times this amount.   4. Method according to any one of the claims   1 to 3, characterized in that said polyoxyalkylene polyol and said polyisocyanate react, at a ratio NCO / OH equivalent from 1.5 to 100.   5. Method according to any one of the claims   1 to 4, characterized in that said aqueous mixture of urethane prepolymer further contains a polymer of inert bond.   6. Method according to claim 5, characterized   in that said binding polymer is poly- acetate   vinyl, an ethylene-vinyl acetate copolymer or a   ethylene-vinyl acetate-vinyl versatate copolymer.   7. Method according to any one of the preceding claims, characterized in that the said materials   particulate plants are selected from sawdust, frag-   wood, cork powder, rice bran, olive flour   gineux, soya flour, rice husk or other cereals,   finely divided straw or bark.   8. Process according to any one of the claims   tions, characterized in that the operation of   forming includes compression molding.   9. Process according to any one of the claims.   previous cations, characterized in that it comprises   in addition to the compacting operation of the articles formed,   tants, by application of heat and pressure.   10. Process according to claim 9, characterized in that the said compacting operation is carried out at a temperature of 70 to 200 C and under a pressure of 2 x 105 to x 105 Pa.