JP3345013B2 - Apparatus and method for producing fibrous starch raw material - Google Patents

Abstract

Process and device for the production of fibrous starch materials through extrusion of a dispersion or aqueous solution of starch material in a flow of saline coagulant, in which the dispersion or aqueous solution is extruded through a microporous tubular wall in a chamber circularly ringed with said microporous wall in such a way to obtain an extrusion flux of the starch material which surrounds the said tubular walls and the coagulation of the extrusion is carried out by feeding the flow of the coagulation agent in the annular chamber parallel to the extrusion surface. The said obtained fibres in particular have applications in the paper sector in substitution for or in combination with cellulose fibres.

Description

The present invention relates to an apparatus and a method for producing fibrous starch materials, especially those used in the production of paper and paperboard.

Typically 5 to 40% by weight of starch in anhydrous solid form
It is known that when an aqueous colloidal dispersion of starch containing a concentration of is contacted with a non-solvent (eg, a solution of ammonium sulfate in saline), it solidifies to form gel flakes.

U.S. Pat. No. 4,205,025 describes a method for producing fibrils using a film-forming polymer such as substantially water-soluble starch. This fibril is used as paper pulp. The term "fibrils" intends a material that exhibits a hybrid morphology between the film and the fibers. The film-forming polymer is dissolved in water to form a solution, which is then poured into a precipitation means, preferably an organic non-solvent, such as an alcohol or ketone, while applying a shear force to form fibrils; The fibrils are rendered more hydrophobic by subsequent treatment in an insolubilizing agent.

U.S. Pat. No. 4,340,442 discloses a saline solution, to improve the fibril hydrophobicity,
In particular, a method of making fibrils using a water-insoluble starch having a high amylose content (50-80% by weight) which solidifies in ammonium sulfate is described. The starch, which is substantially insoluble in water, requires a step of dissolving it in an alkaline solution, which involves various problems in the coagulation step and the sulfuric acid, different from the ammonium salt, produced in said step. This leads to problems with salt removal.

U.S. Pat. No. 4,139,699 describes a process for producing a product having a starch fiber morphology by extruding a colloidal starch dispersion having a high amylopectin content into a coagulant. If a starch having an amylopectin content of less than about 95% is used, it must be chemically modified to ensure that the starch is a colloidal dispersion in an aqueous system, or alternatively, the starch may be alkali-hydroxylated. Must be dissolved in the presence of the substance.

The use of alkali hydroxides, especially sodium hydroxide, precludes the above method in that ammonia is formed in the coagulation step performed with ammonium sulfate and large amounts of sodium sulfate are generated, preventing coagulation and causing disposal problems. It makes it difficult to apply industrially.

U.S. Pat. No. 4,243,480 describes a process for using the product produced by the process described in U.S. Pat. No. 4,139,699 for the production of paper or paperboard by conventional papermaking techniques. The product has the form of short fibers having a diameter of 10 to 500 microns and a length of 0.1 to 3 mm obtained by extruding a starch dispersion through a die into a moving coagulation bath.

U.S. Pat.No. 4,853,168 describes U.S. Pat.No. 4,139,699 wherein a colloidal starch dispersion adapted for extrusion is obtained by steaming an aqueous starch dispersion containing an aqueous salt solution for coagulation. Are described.

In the above-mentioned patent documents and practical experiments, various known devices, such as spray nozzles, ejectors, mixers with stirrers, for finely dividing the starch solution or dispersion and thereby promoting intimate contact with the coagulant , A spinneret or a syringe may be used. However,
It has been experimentally shown that the equipment used of this type strongly influences the final solidification product and its properties.
Devices that coagulate starch under highly turbulent conditions (e.g., ejectors) or devices that do not have an ordered velocity profile (e.g., mixers with stirrers) do not yield products having a fibrous structure and are flat-scale (wound together) rolled up)) or induces starch breakdown to some extent while forming three-dimensional aggregates.

The dimensions of these non-fibrous products vary with operating conditions and affect their properties. In the manufacturing process, fine particles are lost during separation, and they block the fabric, which slows down the filtration operation. When used in papermaking, these fine particles are not retained on flat fabrics with consequent loss of starch in the paper and increased COD in paper mill effluent. On the other hand, macroparticles cause drawbacks in papers made without integration with cellulose matrix fibers.

Another negative aspect identified for the fibrids obtained in the manner described above is the considerably higher water retention and solubility values.

Yet another product obtained from starch by a coagulation process but having a fibrous morphology is that it is easier to filter because of its increased affinity for cellulose fibers due to its fiber structure. The above disadvantages are overcome, if not completely, in that the water retention is reduced and the solubility is reduced due to the smaller specific surface area.

Therefore, the dimensions, size distribution and size, suitable for the production of paper and paperboard, and which can be obtained from low-cost starches such as starch from corn or potato without using the starch used as an alkaline solution It would be desirable to have a method for producing a product having a fiber morphology with physicochemical properties.

In view of such an object, an object of the present invention is a method for producing a fibrous starch material by extruding a dispersion or aqueous solution of a starch material into a stream of brine coagulant,
The following operations are performed:-the dispersion or aqueous solution is passed through the microporous tubular wall,
Extruding into an annular chamber coaxially arranged with the microporous wall; and- solidifying the extrudate by feeding a flow of coagulant into the annular chamber parallel to the extrusion surface. The above method is characterized by including the above.

Another object of the present invention is: a tubular body having a first inlet means for supplying a stream of starch material; a supply chamber of starch raw material connected to said first inlet means; An annular outlet chamber, arranged coaxially with said outlet chamber and interposed between said outlet chamber and said feed chamber; for passing various filaments of starch material around which an envelope is formed into a hole wall. A tubular element having a perforated wall adapted to extrude through said outlet chamber through:-second inlet means connected with said outlet chamber for supplying a flow of coagulant; and-of said annular outlet chamber This is a fiber production device, which includes a discharge means disposed downstream.

By using the method and apparatus of the present invention, 75
It has a shape with a specific narrow size distribution centered around ~ 100 microns and "Anthrone Tes
t) "(discussed below) and found to be possible to obtain a product having a water solubility of less than about 2% and a low water retention. Further advantages and features of the method, the device and the product obtained according to the invention are explained in more detail with reference to the accompanying drawings.

FIG. 1 shows a flowchart of a plant for carrying out the method of the present invention, FIG. 2 shows a cross-sectional view of a fiber manufacturing apparatus according to the present invention, FIG. 3 shows a cross-sectional view of another embodiment of the present fiber manufacturing apparatus,
FIG. 4 is an enlarged detailed view of a part of FIGS. 2 and 3.

In FIG. 1, 1 denotes a dispersion in a stirred state for producing a starch suspension in water having a dry weight of typically 5 to 50% by weight, preferably 10 to 40% by weight. The starch used for preparing the suspension is preferably a natural starch having an amylopectin content of 30 to 100%, such as starch from corn, rice, tapioca, potato. Particularly preferred are widely marketed corn starches having a typical amylopectin content of 64-80% by weight. Within the scope of the present invention, starches having a high amylose content, such as amylomises and chemically or physically modified starches, can be used.

Starch suspensions may also contain additives such as salts (e.g., salt coagulants as described in U.S. Patent No. 4,853,168), alkalis, organic bulking or minerals, crosslinkers, plasticizers, polyoxyethylene. , Polyvinyl alcohol, ionomeric polymers such as copolymers of ethylene and acrylic acid and / or maleic anhydride, polyacrylates, polyamides, lubricants such as lecithin, fatty acids, esters and amides of fatty acids.

The suspension held in the disperser, which is under agitation at ambient temperature, is then pumped via a gear pump 2 to a jet steamer (indicated by 3), where the desired steaming temperature is reached. In a co-current with steam in a suitable manner. Jet steaming is known per se and involves immediately heating an aqueous suspension with process steam and then holding the heated liquid for a predetermined period of time. Generally 90 to 180
A cooking temperature of ° C. is selected during this process depending on the particular starch used. Care should be taken to avoid excessively high temperatures that would cause the degradation of the starch material, especially while ensuring that the temperature, application shear time, and holding time are such that a dispersion close to full gelation can be obtained. Should.

At the outlet of the jet steamer, the starch dispersion or solution to be steamed is stirred in the aligned stirring reactor 4 and recovered in the casing at a temperature of about 100 ° C. while circulating water.
A flush is performed in this aligned tank to release excess water vapor and return to a starch / water concentration close to the initial concentration.

From the reactor 4, the starch is supplied to the heat exchanger 6 via the pump 5.
Pumped therein, where it is brought to a temperature of about 20-100 ° C, preferably 40-70 ° C. From the heat exchanger, the starch is fed to a fiber making device of the type shown in FIGS. 2 and 3 where the salt coagulant described below is also injected. Salts which can be used within the scope of the present invention are ammonium sulfate, magnesium sulfate, aluminum sulfate, ammonium phosphate, sodium chloride, sodium sulfate, sodium carbonate, sodium bicarbonate and ammonium chloride. A preferred aqueous salt solution is a saturated solution of ammonium sulfate, although it is not necessary to reach the saturation level of the above salts and it is equally possible to use concentrations below the saturation level.

The starch fibers obtained from the fiber production equipment are collected in a stirring reactor 8 for aging and subsequent decantation. After decantation, the clarified material is recirculated by pump 9 and mixed with a saturated salt aqueous solution of a coagulant before being reused to extract the starch.

The clarified material circulating in the apparatus as a coagulant contains aqueous salt solutions and fine fibers that are not decanted in the collection vessel due to their small size.

The fiber mass from reactor 8 is pumped onto filter 11
Pumped by 10. The fiber is then recovered in vessel 12 while the filtrate is fed to vessel 13 where it is mixed with the clarified material from pump 9 and then recirculated in an aqueous salt solution adapted to be fed to fiber making device 7 Add sulfate.

Appropriate number of aging and decanting reactors 8
The process according to the invention can be carried out continuously, whereby starch fibers are obtained which can be washed directly on the filter or which can be easily filtered and subsequently washed.

The fiber production device 7 in the embodiment of FIG. 2 comprises at least one inlet 15 used to supply the starch material under normal conditions, an inlet 16 for the purpose of supplying a coagulant, and a starch fiber produced after coagulation. Includes outlet 17 for discharge.

The starch material is introduced from the inlet 15 into a wall 19 with radial holes.
Is immersed in a tubular duct 18 provided halfway. The perforated wall member 19 acts as a distributor to direct the starch material stream in the direction of the supply chamber 21.

With reference to 22, there is shown a tubular element having microporous walls suitable for extruding the starch material from the feed chamber 21 into an annular chamber 23 coaxial therewith. Chamber 23 is between the radially outer surface of element 22 and the radially inner surface of member 14.

The tubular element 22 preferably has a pore size distribution of 10 to 500.
It can consist of a porous sintered metal material that is microns.

In another embodiment, the tubular element 22 is formed by machining and has a number of radially perforated metal having at least one narrow flow area with openings preferably having dimensions of 10 to 500 microns. It may be a material, for example, a member of stainless steel. Preferably, the radial holes have a narrow opening, typically an opening of 10 to 500 microns, an inlet portion 24 for the starch material and a larger sized opening, preferably 0.5 to 1.5.
It has a cross section as shown in FIG. 4 with an outlet part of the starch raw material with an opening of mm.

The orifice density on the extruded surface (intended as the surface of the tubular element in contact with the coagulant), expressed as a ratio of the number of pores to the surface area, is preferably between 4 and 0.05 pores / mm ² .

The coagulant supplied through the inlet opening 16 flows through an annular element 26 having a crown of an axial hole 27 acting as a distributor, and is defined by a tubular element coaxial with the wall 14 and the member 29 of the textile production apparatus. First annular chamber 28
Supplied inside. From chamber 28, the stream is fed to an annular chamber at outlet 23 parallel to the radially outer surface of microporous element 22, where the coagulant stream interacts with the extruded stream of starch material.

The starch material is extruded in the form of various filaments surrounding the extruded surface in the form of a tubular film.

Preferably, the flow rate of the brine coagulant in the annular section of the outlet chamber 23 is maintained at 1 to 15 m / s.

It is intended by the ratio of the flow rate of the coagulant in the annular section of the chamber 23 to the rate of the starch material at the outlet of the pores of the microporous wall (defined by the ratio of the flow rate of the starch material to the total area at the outlet hole). The draw ratio is generally 1 to 1000, preferably
100-1000. The axial length of the outlet chamber 23 is preferably such that a residence time of 5 to 15 milliseconds of starch material is obtained. In any case, the axial length of the chamber 23 in which the starch material is to be withdrawn must be such that the stretching of the starch material takes place and at the same time a complete phase change takes place.

At the outlet of the chamber 23, the extruded flow is supplied to the annular chamber 30 in a section which increases rapidly in the direction of flow.

In the embodiment of the fiber production apparatus shown in FIG. 3, a stream of starch material is supplied via an inlet 31 to an annular chamber 32 defined by the wall of the member 14 and the microporous wall-like tubular element 33. The flow of starch material flows radially inward through the walls of the element 33 into an annular outlet chamber 34 between the tube element 33 and a central core 35 coaxial with the body. The flow of coagulant is fed across an inlet 36 and into a pre-chamber 37 and across a hole 39 in an annular element 38 into a chamber 40 and from the chamber 40 to an outlet chamber 34 having a narrow cross section in a flow manner. You.

In this embodiment, the cross section of the holes of the microporous element 33 remains the same as in FIG. In this case, however, the flow of the starch material proceeds from a large cross section to a small cross section, causing an increase in the starch flow rate and necking down of the starch thread.
ing down). The material leaving the holes is solidified by the coagulant in the annular chamber. If the best conditions for coagulation are a draw ratio of preferably 1 to 150, the release rate of the starch material from the pores into the microporous wall 33 is preferably 0.1 to 1 m / s.

The fiber manufacturing apparatus that is one of the subjects of the present invention offers the following distinct advantages, for example: Providing a product with a fibrous structure through coagulation of the starch material.

Its structure with cylindrical symmetry ensures the homogeneity of the hydrodynamic conditions, thus eliminating possible border effects.

-Its dimensions are fully known, so the project evaluation criteria are valid.

-Knowledge of the above criteria can be scaled up.

Another advantage provided by using the above-described fiber manufacturing apparatus is emphasized by the following example.

Example 1 Using the plant shown in FIG. 1, corn starch fiber was obtained by operating under the following conditions.

-Starch concentration in the dispersion: 15% by weight (anhydrous starch)-maximum cooking temperature in a jet steamer: 115 ° C (preferable temperature range is 100-130 ° C)-starch temperature at the inlet of the fiber production equipment: 60 -Salt aqueous solution: ammonium sulfate: 41% by weight-Temperature of the salt aqueous solution at the inlet of the fiber manufacturing device: 21 ° C-Maximum speed of the salt aqueous solution at the outlet room of the fiber manufacturing device: 7
m / s-Flow rate of starch after steaming: 48 L / h-Fiber manufacturing apparatus as shown in Fig. 2 having an extruded sintered body made of a sintered metal having a porosity (average diameter of pores) of 40 microns- Length of outlet chamber (23, 24) of fiber manufacturing apparatus: 10 cm-Average aging time before filtration: 4 hours.

By carrying out the method according to the above conditions, starch fibers having the following size distribution (expressed in% by weight) measured according to the Bauer McNett apparatus were obtained.

595 μm (28 mesh)%: 0.3 297 μm (40 mesh)%: 3.1 149 μm (100 mesh)%: 68.5 74 μm (200 mesh)%: 21.3 min. 200 min × 100: 6.8 Solubility and characteristics of the obtained fiber The measurement was performed using the following method.

Washing of the filter panel from the plant; water (500 ml) by mechanically stirring 100 g of the filter cake with a glass anchor stirrer under the following conditions:
Disperse in.

Becker having a diameter of 10 cm and a height of 20 cm (Becke
r); mechanical glass anchor stirrer (length = 40cm; length 8c)
m, 8 cm high with stirring blades); temperature = 20 ° C .; stirring time 30 minutes; rotation speed 500 rpm).

The resulting dispersion was treated with a Bruckner (Br) having a diameter of 30 cm.
on a uckner) under a vacuum of 10 mm Hg in the presence of a paper filter.

Filter the liquid twice on the same panel. Then washed panel with H ₂ O in 500 ml. The ratio of starch to water in the wash is 1:10.

Solubility measurements are made on the filtered product to separate the product from water and washed to remove flocculants. The product is dispersed in water in a conventional laboratory pulper (dryness 0.2%, rotation speed 3000 rpm). Samples were removed after filtration in 4 hours and the 8 micron filter paper, measured using a reagent starch in solution "Anse Loan (ANTHRONE)" (0.2% ans loan solution in 96% H ₂ SO ₄₎ I do.

The solubility values determined according to the method described above on the filter panels obtained according to the examples are less than 1.5%.

 The morphological characteristics of the obtained fiber are shown in FIG.

Example 2 The test according to Example 1 was repeated with the only difference being the characteristics of the microporous sintered filter constituted in the case of a sintered metal tube with holes having an average diameter of 100 μm. Fibers having the following size distribution in% by weight were obtained:

595 μm (28 mesh)%: 0.3 297 μm (40 mesh)%: 0.9 149 μm (100 mesh)%: 63 74 μm (200 mesh)%: 25.2 Min. Over 200 mesh × 100: 10.6 This result indicates that the average diameter of the holes is This shows that the fiber distribution is not affected, that is, it is kept at 100 and 200 mesh.

The solubility values obtained by the method of Example 1 are again less than 1.5% as before.

Example 3 (Comparative) The characteristics of the fibers obtained from the test of Example 1 are compared with fibrids obtained with another fiber-making apparatus, in particular with an ejector and a spinneret.

 The process conditions are the same as in Example 1.

The first fiber manufacturing apparatus comprises an ejector having eight holes of 1 mm in diameter at a starch inlet having an inclination of 45 ° with respect to an ejector axis arranged in a groove. The velocity of the coagulant (ammonium sulphate) in the thinning zone is equal to 31 m / s and the withdrawal ratio (defined as the ratio of the maximum velocity of the sulphate to the maximum velocity of the starch leaving the pores) is equal to 47.

The second fiber production apparatus includes a spinneret having 113 holes having a diameter of 0.5 mm. The spinneret is placed in a circular (tubular) duct and supplies a coagulant, ammonium sulfate, to the annular crown between the outer surface of the spinneret and the inner wall of the tubular duct. The speed of the ammonium sulfate and the speed of the starch material exiting the hole are parallel. At the hole exit, the resulting suspension was then convergent (30 m / s
Having a minimum diameter of 4 mm, corresponding to the sulfate velocity of), where turbulence completes the solidification.

Table 1 reports a comparison of fiber distribution for the various products, as shown here, for the ejected fibers, there was a high percentage of fine particles (80%), which was passed through a spinneret or tubing. Decrease if The distribution curves also differ between these two types of fiber manufacturing equipment. In other words, it is very narrow (90%
Particle size of 100 to 200 mesh), and wider for spinneret.

In particle form (for example, in the case of tubing, similar to fibers with a pronounced form ratio; in the case of spinnerets, they have a high film content, similar to fibers that are curled and do not have preferential orientation) This size distribution combined with
It is the reason that these two products exhibit different fist movements when producing paper with cellulose fibers. In fact, the product obtained from the tubular fiber production equipment does not cause problems in the production of sheets in the laboratory (forming and drying problems), while using the product from the spinneret,
It has been experimentally confirmed that starting from a certain percentage it gives a sheet which has surface defects and which tends to stick on the sheet forming plate.

Table 2 shows paper made in a laboratory using a Rapid-Keothen apparatus after dispersing the cellulose-starch material paste (the latter 10%) in a pulper at 3000 rpm for 2 hours at ambient temperature. 5 reports the percentage of starch retained on the sheet. As shown here, the highest retention was achieved with articles obtained from tubular fiber manufacturing equipment.

Finally, Table 3 highlights the peculiarities of the two different products when filtered from the slurry after coagulation and washing until the ammonium sulfate has been eliminated (slurry concentration and aging time are equal). As noted, the product obtained from the tubular fiber production equipment shows twice the productivity as from the spinneret.

Still further, another object of the present invention has a solubility of less than 2% and a size such that 90% after classification with a Bauer-McNett device falls in the range of 100 to 200 mesh. It is a starch fiber obtainable by the above method, which is characterized by having a dimensional distribution.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Zanardi Gino, I-28067 Pernate, Italy, Strada Posescione, 45 (56) References JP-A-5-302297 (JP, A) JP-A-52-118034 (JP, A) JP-A-49-47609 (JP, A) JP-B-44-30451 (JP, B1) JP-B-49-41127 (JP, B1) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) D01D 5/06 103 D01F 9/00 D21H 13/30

Claims (13)

(57) [Claims] 1. A process for producing fibers of a starch material by extruding an aqueous dispersion or solution of a starch material into a stream of brine coagulant, comprising the steps of: Extruding through a microporous tubular wall into an annular chamber arranged coaxially with said microporous wall, by feeding a flow of coagulant parallel to the extrusion surface into said annular chamber, Performing the coagulation of the method. 2. The method of claim 1, wherein said microporous wall has a pore group having at least an area having an average diameter of 10 to 500 microns and an extruded surface pore density of 4 to 0.05 holes / mm ^2. the method of. 3. Extruding through the holes on the microporous wall from a narrow inlet section having an opening size of 10 to 500 microns to a larger outlet section having an opening size larger than the narrower section. 3. The method according to claim 2, wherein the method is performed at a draw ratio of from 1 to 1000. 4. Extrusion through the hole on the microporous wall from a relatively large inlet section to a narrow outlet section having an opening size of 10 to 500 microns and smaller than the opening of the large inlet section. 3. The method according to claim 2, wherein the method is performed at a draw ratio of 1 to 150. 5. The method according to claim 1, wherein the residence time of the starch material in the annular chamber is between 5 and 15 milliseconds. 6. A tubular member (14) having first inlet means (16, 31) for supplying a stream of starch material;-a supply chamber (21) for a starch material connected to said first inlet means. 32), an annular outlet chamber (23, 34) of the starch material, arranged coaxially with said outlet chamber (23, 34) and between said outlet chamber and the supply chamber (21, 32); A tubular element (22,33) having a perforated wall adapted to extrude various filaments of starch material into the outlet chamber; connecting with the outlet chamber for supplying a coagulant stream; An apparatus for producing fibers, comprising a second inlet means (16, 36) and a discharge means (17, 30) arranged downstream of and connected to the annular outlet chamber. 7. The tubular element (22,33) having a porous wall comprises:
7. The fiber producing apparatus according to claim 6, wherein the apparatus is made of a sintered metal having pores having a distribution of 0 to 500 microns. 8. The tubular element (22,33) having a hole wall is provided with 10
7. Fiber according to claim 6, characterized in that it is a cylindrical element with a bore wall having a plurality of radial through-holes (24,25) having at least one narrow part having a dimension of from .about.500 microns. manufacturing device. 9. The method as set forth in claim 1, wherein said holes are 4 to 0.05 holes / m on the extrusion surface.
device range paragraph 7 or paragraph 8, wherein claims having a surface density of m ^2. 10. Apparatus according to claim 8, wherein said annular outlet chamber (23) of starch material is coaxial with and radially outside said supply chamber (21). 11. A portion (24) in which said radial holes connect with a supply chamber (21) and have an opening size of 10 to 500 microns, and an opening in said portion (24) which connects with said outlet chamber. The part with the opening size larger than the size (2
11. The device according to claim 10, comprising 5). 12. The annular outlet chamber (34) is connected to the supply chamber (3).
9. Apparatus according to claim 8, coaxial with 2) and radially inside it. 13. The radial hole is connected to an outlet chamber (34) and has an opening size of 10 to 500 microns (24), and is connected to a supply chamber (32) and said part (2).
13. The device according to claim 12, comprising a portion (25) having an opening size larger than the opening size of 4).