CA1104856A - Pulp refining element - Google Patents
Pulp refining elementInfo
- Publication number
- CA1104856A CA1104856A CA333,851A CA333851A CA1104856A CA 1104856 A CA1104856 A CA 1104856A CA 333851 A CA333851 A CA 333851A CA 1104856 A CA1104856 A CA 1104856A
- Authority
- CA
- Canada
- Prior art keywords
- pulp
- pulp refining
- resins
- synthetic polymer
- polymer resin
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D1/00—Methods of beating or refining; Beaters of the Hollander type
- D21D1/20—Methods of refining
- D21D1/30—Disc mills
- D21D1/306—Discs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C7/00—Crushing or disintegrating by disc mills
- B02C7/11—Details
- B02C7/12—Shape or construction of discs
Landscapes
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Paper (AREA)
- Polishing Bodies And Polishing Tools (AREA)
Abstract
PULP REFINING ELEMENT
ABSTRACT OF THE DISCLOSURE
A pulp refining element effective for producing a high quality of pulp with a low specific power consumption, is provided with a number of grooves extending from a feed end zone of the element to which a fibrous material is fed to a discharge end zone of the element from which a refined pulp is discharged, and a number of ribs defining the grooves therebetween, and is characterized in that the bottom of at least a discharge end portion of the grooves is covered with a layer of a synthetic polymer resin in such a manner that the distance from the outer surface of the resin layer to the level of the tips of the ribs is in a range of from 0 to 3 mm.
ABSTRACT OF THE DISCLOSURE
A pulp refining element effective for producing a high quality of pulp with a low specific power consumption, is provided with a number of grooves extending from a feed end zone of the element to which a fibrous material is fed to a discharge end zone of the element from which a refined pulp is discharged, and a number of ribs defining the grooves therebetween, and is characterized in that the bottom of at least a discharge end portion of the grooves is covered with a layer of a synthetic polymer resin in such a manner that the distance from the outer surface of the resin layer to the level of the tips of the ribs is in a range of from 0 to 3 mm.
Description
PULP REFINING ELEMENT
FIELD OF TI-IE INVENTION
The present invention rela-tes to pulp refining elements. More particularly, the present invention relates to a pair of elements for use in a refiner with a decreased consumption of energy and for producing cellulosic pwlp useful for making a high quality of paper.
BACKGROUND OF THE INVENTION
It is known that raw or mechanically, thermally and/or chemically treated cellulosic fibrous material, for example, wood chips, is conver-ted into pulp by means of a beating or refining process. The beating or refining process is an important process for producing pulp for making paper.
The beating process is usually applied to a chemically treated fibrous material suspended in a content of about 10% or less in water, by using a beater.
The refining process can be applied to any-of the raw and mechanically, thermally and/or chemically treated fibrous materials by using a refiner. This refining process is very effectlve for defibering the fibrous material into individual fibers and for the outer and inter fibrillations and the cutting of the individual fibers, so as to provide refined fibers having a proper thickness, llength and surface area~ and to enhance the swelling property and flexibility of the fibers. That is, the pulp useful for maklng a high quality of paper can be . ,~
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obtained only by using the re~ining process.
The refining process can be conducted by using a disc type refiner, conical type refiner or drum type refiner.
The disc type refiner is provided with a pair of refining elements (discs), each having a pulp refining surface facing and parallel to the other, and closely spaced from the other so as to form a very narrow gap bet~een the pulp refining surfaces. At least one of the elements is rotatable relative to the other. Each of -the pulp refining surfaces has a feed end zone to which the fibrous material to be refined is fed, and a discharge end zone from which the resultant refined pulp is discharged.
Also, each of the pulp refining surfaces of the disc type refiner is provided with a number of grooves extending from the feed end zone to the discharge end zone of the pulp refining surface, and a nlamber of ribs defining the grooves therebetween.
In the dlsc type refiner, either one or both of the elements are rotatable relative to the other. That is, in the former case, one of the elements is fixed and the other one is rotatable at a predetermined speed. In the later case, both the elements are rotatable in an opposite dlrection to each other. In the refining process, by using the disc type refiner, the fibrous material is fed to a portion of the gap between the pulp refining surfaces, correspondinq to the feed end Eones of the surfaces, travels through the gap while being refined, and then, is : ~ :
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discharged through a portion of the gap corresponding to the discharge end zones of the surfaces.
The conical type refiner is provided with a cone--shaped rotor element having a pulp refining outside surface, the rotor element being contained in a shell element having a cone-shaped pulp refining inside surface surrounding the outside surface of the rotor. Usually, the shell element is fixed unrotatably and the rotor element is rotatable. Each of the conical outside surfaces of the rotor element and the conical inside surfaces ~f the shell element has a feed end zone located in a small diameter portion of the conical surface, and a discharge end zone located in a large diameter portion of the conical surface. Also, each of the conical inside and outside surfaces of the rotor element and shell element, is provided with a number of grooves extencling in a straight line, or in a spiral configuration, from the feed end zone to the discharge end zone of each conical surface. In the refining process by using the conical type refiner, the fibrous material is fed into a feed end portion of the gap between the conical inside and outside surfaces, travels through the gap while being refined, and then, is discharged through a discharge end portion of the gap.
The drum type refiner is provided with a drum-shaped `~ :
rotor element having a drum-shaped outside peripheral ; surface, and an unrotatable shell element. The inside ~; peripheral surface of the shell element faces at least a part of the outside peripheral surface of the rotor element '. , . . `
, ` , ', , '' ' ' '. ' '' " ~ : ' ''`
. ' ` ' ' " '' ' ' ~ ` ' ' ' ,~ ' ' `, '' ` ' ' ' :, ~ ' _ a, --in a parallel relationship. The outside peripheral surface of the drum-shaped rotor element is provided with a number of -the grooves extending in a straight line, or in a spiral curve, from a feed end zone located on an end portion of the drum-shaped surface to a discharge end zone located on the opposite end portion of the drum~shaped surface, and a number of ribs defining the grooves there-between. The inside surface of the unrotatable sheel element may be made of an abrassive stone, such as basalt or lava. Otherwiser the inside surface of the shell may have a number of grooves and ribs extendiny in the same manner as that in the outside peripheral surface of the drum-shaped rotor element. In the refining operations, by using the drum type refiner, the fibrous material is forced to travel through the gap between the outside peripheral surface of the rotor element and the inside surface of the shell element from a feed end portion to a discharge end portion of the gap, by means of a pump, while being refined.
The refining process applied to the fibrous material is effective for enhancing the outer and inner fibrillations of the refined fibers. This is also effective for enhancing the swelling property and the flexibility of the fibers.
The above-mentioned refiners can be used for the purpose of beating the fibrous materials. Accordingly, the above-mentioned refining process and beating process can be involved in term "refining process" in a wide meaning.
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With respect to the reEining mechanism in the reiiner, it is recognized that the fibrous material is defibered when the fibrous material is brought into contact with the edges of the ribs, and -the defibered fibers are cut and/or compressed by the edges of the rotating ribs.
Also, it is recognized that, during the refining process the defibered fibers travel from the feed end zone to the discharge end zone through the grooves. That is, the function of the grooves is merely recognized as a path ~or the defibered fibers. For example, Goncharov, Bumazh Pro. No. 5, 12-14(1971), discloses that, when an unbleached sulfite pulp is refined with a disc type refiner, a very strong force is applied onto a part of a rib from a tip thereof to a level of 2.5 or 3 mm distant from the tip.
That is, when the refining operation is carried out under ordinary conditions, the force applied to the tip part of the rib is about 35 kg/cm2. This value of the force corresponds to about 13 times an average value of the force per unit area, cm2, applied to the entire outer area of the rib.
That is, the refining effect is attained mainly by the tip end portion of the rib, and the tip end portion is worn away during the refining process.
However, van der Akker (Fundamentals of Papermaking Fibres, Trans~ of the Symposium held at Cambridge, September, 1957, pages 435 through 446) states that about 99.9% of the energy applied to a refiner is spend for wearing away the ribs and converted to heat, and only about ~.1% of the , ~ . .
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applied energy is utilized to refine the fibrous material~
It is known that the specific power consurnption in the operation of the refining process for refining chemical pulp is about 200 to 800 kWh/T, the specific power consump-tion for producing mechanical pulp from a refiner mechanicalpulp (RMP) is about 1400 to 1800 kWh/T and that from a thermomechanical pulp (T~P) is about 2000 kWh/T or more.
That is, the power consumption necessary for refining -the fibrous ma-terial by using a conventional refiner is very large. Accordingly, it is strongly desirable to enhance the efficiency of the refiner, so as to decrease the consumption of enexgy necessary for refining the fibrous material.
In the field of various types of refiners, it is believed that the depth of the grooves in the pulp refining surface should be at least 4 mm, because a depth of less than 4 mm results in a poor flow of the ~ibrous material between the pulp refining surfaces under an ordinary pressure. For example, P. J. Leider and J. Rihs, Tappi, Vol. 60, No. 9tl977), pages 98 through 102, state that the decrease in the depth of the groove causes the throughput of the fibrous material to decrease and that, when the depth of the grooves is l/8 inch labout 3.2 mm), no flow of the fibrous material occurs. In order to force the fibrous matexial to flow through the groove having a depth less than 4 mm, it is necessary to increase the pressure applied to the fibrous mateial. The increase in the pressure results in an increase in the consumption of : -- . - . . . . . . :
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energy for refining the fibrous material.
However, grooves having a depth of 4 mm or more, cause a portion of the fibrous material fed into the refiner to ~e accumulated in the grooves. The accumulated fibrous material forms a thick ma-t which is fixed unmovably in the groove. The mat acts as a force absor~er when the fibrous material is exposed to the refining action of the pulp refining surfaces. Therefore, the formation of the mats in the grooves causes the efficiency of the refining process to decrease.
U.S. Patent 3,745,645 discloses a method for fabricat-ing and operating a pair of relatively rotatable elemen-ts having ribs and grooves formed between the ribs. The height of the ribs (the depth of the grooves) is in a range of from about 1.5 to about 5.0 times the width of the ribs at the tips thereof. The grooves are partly filled with a plastic filler material. When the tips of the ribs wear down during the refining process, the height of the filler material is reduced, so as to restore the unfilled por-tion of the grooves substantially to the original depth thereof. This U.S. patent discloses grooves having a depth of 12 mm and partly filled with the filler material having a height of 8 mm, so as to leave a 4 mm free space at the top of the grooves. That is, in the refiner of this U.S. patent, since the depth of the grooves filled with the filler material is 4 mm, the grooves cannot prevent the formation of the thick mat of the fibrous material. In other words, the refiner of the U.S.
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patent cannot decrease -the comsumption of energ~ for the refining process.
SUMMARY OF THE INVENl'ION
An object of the present invention is to provide a pulp refining element for the use in a pulp refiner, which element is effective for causing -the refiner to opera-te with a high efficiency and wit:h a low consumption of energy.
Another object of the present invention is to provide a pulp refining element for the use in a pulp refiner, which element is effective for producing a enhanced quality of pulp.
The above-mentioned objects can be a-ttained by the refining element of the present invention, which element has a pulp refining surface having a feed end zone thereof to which a fibrous material is fed and a discharge end zone thereof from which the refined pulp is discharged, the pulp refining surface being provided with a number of grooves extending from the feed end zone to the discharge end zone of the pulp refining surface and a number of ribs defining the grooves therebetween, and which element is characterized in that the bottom of at least a portion of the grooves, the portion being located in the discharge end zone of the pulp refining surface, is covered with a layer of a synthetic polymer resin in such a manner that the outer surface of the synthetic polymer resin layer in a groove is O to 3 mm distant : from the level of the tips of the ribs defining the groove ..
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therebetween toward -the bottom.
In the pulp refining element, it is important that the bottoms of at least por-tions of the grooves located in the discharge end zone of the pulp refining surEace be 5 covered with a layer of a synthetic polymer resin. Also, it is important that the distance from the outer surface of the synthetic polymer resin layer in a groove to the level of the tips of the ribs defining the groo~e there-between, that is, the depth of a free space above the synthetic polymer resin layer in a groove, be in a range of from 0 to 3 mm.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 is fragmentary plan view of an embodiment of the pulp refining surface of the element of the present invention for use in a disc type refiner;
Fig. 2 is a fragmentary perspective view of an embodiment of the pulp refinin~3 element of the present invention for use in a disc type refiner;
Fig. 3 is a cross-sectional view of a pair of pulp refining elements of the present invention for use in a ; conical type refiner;
Fig. 4 is a graph showing a relation between a weight percent of a fraction of a refined pulp remaining on a 24 mesh screen and an unscreened freeness of the ,~ 25 refined pulp;
Fig. 5 is a graph showing a relation between a breakiny length of a refined pulp and a screened freeness of the refined pulp;
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Fig. 6 is a yraph showing a relation between a tear factor of a refined pulp and a screened freeness of the refined pulp;
Fig. 7 is a graph showing a relation between a breaking length of a refined pulp and a specific power consumption in the production of the refined pulp;
Fig. 8 is a graph showing a relation between a scattering coefficiert of a refined pulp and a specific power consumption in the production of the xefined pulp;
Fig. 9 is a graph showing a relation between a -specific power consumption in the production of a refined pulp and an unscreened freeness of the refined pulp;
Fig. 1~ is a graph showing a breaking length of another refined pulp and a specific power consump-tion in the production of the refined pulp, and;
Fig. 11 is a graph showing a scattering coefficient of another refined pulp and a specific power consumption in the production of the refined pulp.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Fig. 1, a pulp refining element usable for a disc type refiner has a pulp refinlng surface 1.
The pulp refining surface 1 contains a feed end zone 2 to which a fibrous material is fed, a discharge end zone 3 from which the resultant refined pulp is discharged, and a middle zone 4 through which the fibrous material travels from the feed end zone 2 to the discharge end zone 3. The pulp refinin~ surface 1 is provided with a number of grooves 5 extending from the feed end zone 2 to the discharge - - .
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end zone 3 through the middle zone ~, and a number of ribs 6 deEining the grooves 5 therebetween.
Referring to Fig. 2, in a discharge end zone oE a pulp refining surface 1 of an element for the use in a disc type refiner, a number of grooves 5 defined by a number of ribs 6, are filled with a synthetic polymer resin. That is, the bottom of each groove 5 is covered with a layer 7 of the synthetic polymer resin.
In a conical type refiner, as illustrated in Fig. 3, a conical rotor 11 has a conical outside surface and a shell 12 has a conical inside surface. Each of the conical outside surface of the rotor 11 and the conical inside surface of the shell 12 is provided with a number of grooves 5, and a number of ribs 6 defining the grooves 5 therebetween. The bottom of each groove is covered with a layer 7 of a synthetic polymer resin.
~iIn the pulp refining element of the present invention, the bottoms o~ the grooves located in at least the discharge end zone of the pulp refining surface/ are each covered with a layer of a synthetic polymer resin. That is, the bottoms of all grooves in the pulp refining surface may be covered with the synthetic polymer resin layers. ~lso, only the bottoms of the grooves located in the discharge end zone may be covered with the synthetic polymer resin layers. Furthermore, the bottoms of the grooves located in the discharge end zone and at least a portion of the ~`~mlddle zone, and/or the feed end zone, may be covered with the syn~thetlc polymer resin~layers.
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The synthetic polymer rPsin usable ~or the present invention is not limited to a special type of polymer resin. That is, the synthetic: polymer resin may be selected from the group consisting of synthetic thermo-plastic polymer resi.ns and synthetic thermosetting polymerresins.
The thermoplastic polymer may be selected from -the group consisting of polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, polypropylene, poly-amides, polycarbonates, polyacetal, polyethersulfones,polyesters, polyphenyleneoxide, modified polyphenyleneoxide, polyimides, polyamideimide acrylonitrile-butadiene-styrene terpolymers, acrylic ester polymers, methacrylic ester polymers, polymethylpentene, polysulfone, polyphenylene sulfide, styrene-maleic anhydride-acrylic ester terpolymers and polytetrafluoroethylene. ~!lore preferable theromplastic polymers for the present invention are polyamides, for example, nylon 11 and nylon 66, polyethylene, especially, high density polyethylene, polypropylene, poly carbonate, polymethylpentene, polysulfones, polyesters, polyphenylene sulfide, polyphenyleneoxide, modified polyphenylene oxides, for example, a blend of poiyphenylene oxides with polystyrene.
The thermosettlng polymer may be selected from the group consisting of phenol resins, diallylphthalate resins, unsaturated polyester resins, alkid resins, epoxy resins, silicone resins, polyurethane resins, melamine resins and uFea resins. More preferable thermosetting . .
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polymers for the present invention are diallylph-thalate resins and epoxy resins.
The synthetic polymer resin layer may contain a large number of pores having a size of 200 microns or less. The pores may be either connected to each other or be independent from each other.
The synthetic polymer r~esin layer may contains one or more additives, for example, pigments, anti-oxidants, fillers and stabilizers. It is preferable that -the synthetic polymer resin be selected from the resins having high resistances to abrasion and deterioration during the refining process, and capable of being easily placed and solidified in the grooves, and readily cut in the preparation of the resin layer~
Moreover, the synthetic polymer resin layer may contain abrasive particles dispersed in at least the outer surface portion of the the synthetic polymer resin layer.
The abrasive particles are effective for promoting the defibering action of the pulp refining surface on the fibrous material and for decreasing the specific power consumption of the refining process.
For example~ when a fibrous material having a ; pulp consistency of 15% is refined by a refiner, it was found that the pressure applied to the surfaces of the grooves is in a range of from 1 to 4 kg/cm2. The surface of the synthetic polymer resin layer containing the abrasive particles can effectively defiber the fibrous -material, even under the above-mentioned low pressure of , ... , - , .. . . ~ , - -' . . ' : . : . - : ' ..
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from 1 to 4 kg/cm2.
The abrasive particles may be selected ~rom the group consistin~ of fine particles of alumina, sil:icon carbide, boron carbide, steel, chromium oxide, iron oxide, garnet, emery siliceous sand, cement, glass and ceramics.
The abrasive particles preferably have an average size of from 50 to 600 microns, and are preferably used in an amount of from 30 to 90% by we:ight.
~ he layer of the synthetic polymer resin may be formed in any conventional methods. For example, a powdered or pelletized thermoplastic polymer resin is placed in the grooves, and mel-ted at an elevated tempera-ture higher than the melting point of the polymer resin, and then, cooled to room temperature, so as to solidify the layers of the polymer resin melt in situ in the grooves. Otherwise, a melt of the thermoplastic polymer resin is poured into the grooves and, then, solidified in situ. In the case where a thermosetting resins is used, a liquid or powdered thermosetting resin precursor is placed into the grooves and heated to an elevated temperature, so as to thermoset the resin precursor in the grooves.
In the case where the abrasive particles are used, the abrasive particles may be uniforml~ mixed with the entire amount of the synthetic polymer resin. Otherwise, the resin layer containing the abrasive particles may be formed in such a manner that a lower half portion of the resin layer is made of a polymer resin containing no abrasive particles and an upper half portion of the resin , - : . ,. --: .
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layer is formed by a mixture of the polymer resin and the abrasive particles.
For example, a resin layer containing the abrasive particles ~ay be prepared by placing a mixture of 7 parts by weight of silicon carbide particles, having a grain size of 60, and 3 parts by weight of a powdered poly-carbonate, in the grooves, pressing the layers of the mixture so as to make the layer of the mixture dense~ and sintering the layer of the mi~ture at a temperature of 235C.
The bottom of the groove is covered with the synthetic polymer resin layer in such a manner that the outer surface of the synthetic polymer resin layer in each groove is 0 to 3 mm, preferably, 0 to 2.5 mm, more preferably, 0.5 to
FIELD OF TI-IE INVENTION
The present invention rela-tes to pulp refining elements. More particularly, the present invention relates to a pair of elements for use in a refiner with a decreased consumption of energy and for producing cellulosic pwlp useful for making a high quality of paper.
BACKGROUND OF THE INVENTION
It is known that raw or mechanically, thermally and/or chemically treated cellulosic fibrous material, for example, wood chips, is conver-ted into pulp by means of a beating or refining process. The beating or refining process is an important process for producing pulp for making paper.
The beating process is usually applied to a chemically treated fibrous material suspended in a content of about 10% or less in water, by using a beater.
The refining process can be applied to any-of the raw and mechanically, thermally and/or chemically treated fibrous materials by using a refiner. This refining process is very effectlve for defibering the fibrous material into individual fibers and for the outer and inter fibrillations and the cutting of the individual fibers, so as to provide refined fibers having a proper thickness, llength and surface area~ and to enhance the swelling property and flexibility of the fibers. That is, the pulp useful for maklng a high quality of paper can be . ,~
.
. ~ . . ..
.
.
. .
. :. ~ ., : . ' ' ~ ~ . : .- -. .. .
obtained only by using the re~ining process.
The refining process can be conducted by using a disc type refiner, conical type refiner or drum type refiner.
The disc type refiner is provided with a pair of refining elements (discs), each having a pulp refining surface facing and parallel to the other, and closely spaced from the other so as to form a very narrow gap bet~een the pulp refining surfaces. At least one of the elements is rotatable relative to the other. Each of -the pulp refining surfaces has a feed end zone to which the fibrous material to be refined is fed, and a discharge end zone from which the resultant refined pulp is discharged.
Also, each of the pulp refining surfaces of the disc type refiner is provided with a number of grooves extending from the feed end zone to the discharge end zone of the pulp refining surface, and a nlamber of ribs defining the grooves therebetween.
In the dlsc type refiner, either one or both of the elements are rotatable relative to the other. That is, in the former case, one of the elements is fixed and the other one is rotatable at a predetermined speed. In the later case, both the elements are rotatable in an opposite dlrection to each other. In the refining process, by using the disc type refiner, the fibrous material is fed to a portion of the gap between the pulp refining surfaces, correspondinq to the feed end Eones of the surfaces, travels through the gap while being refined, and then, is : ~ :
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discharged through a portion of the gap corresponding to the discharge end zones of the surfaces.
The conical type refiner is provided with a cone--shaped rotor element having a pulp refining outside surface, the rotor element being contained in a shell element having a cone-shaped pulp refining inside surface surrounding the outside surface of the rotor. Usually, the shell element is fixed unrotatably and the rotor element is rotatable. Each of the conical outside surfaces of the rotor element and the conical inside surfaces ~f the shell element has a feed end zone located in a small diameter portion of the conical surface, and a discharge end zone located in a large diameter portion of the conical surface. Also, each of the conical inside and outside surfaces of the rotor element and shell element, is provided with a number of grooves extencling in a straight line, or in a spiral configuration, from the feed end zone to the discharge end zone of each conical surface. In the refining process by using the conical type refiner, the fibrous material is fed into a feed end portion of the gap between the conical inside and outside surfaces, travels through the gap while being refined, and then, is discharged through a discharge end portion of the gap.
The drum type refiner is provided with a drum-shaped `~ :
rotor element having a drum-shaped outside peripheral ; surface, and an unrotatable shell element. The inside ~; peripheral surface of the shell element faces at least a part of the outside peripheral surface of the rotor element '. , . . `
, ` , ', , '' ' ' '. ' '' " ~ : ' ''`
. ' ` ' ' " '' ' ' ~ ` ' ' ' ,~ ' ' `, '' ` ' ' ' :, ~ ' _ a, --in a parallel relationship. The outside peripheral surface of the drum-shaped rotor element is provided with a number of -the grooves extending in a straight line, or in a spiral curve, from a feed end zone located on an end portion of the drum-shaped surface to a discharge end zone located on the opposite end portion of the drum~shaped surface, and a number of ribs defining the grooves there-between. The inside surface of the unrotatable sheel element may be made of an abrassive stone, such as basalt or lava. Otherwiser the inside surface of the shell may have a number of grooves and ribs extendiny in the same manner as that in the outside peripheral surface of the drum-shaped rotor element. In the refining operations, by using the drum type refiner, the fibrous material is forced to travel through the gap between the outside peripheral surface of the rotor element and the inside surface of the shell element from a feed end portion to a discharge end portion of the gap, by means of a pump, while being refined.
The refining process applied to the fibrous material is effective for enhancing the outer and inner fibrillations of the refined fibers. This is also effective for enhancing the swelling property and the flexibility of the fibers.
The above-mentioned refiners can be used for the purpose of beating the fibrous materials. Accordingly, the above-mentioned refining process and beating process can be involved in term "refining process" in a wide meaning.
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With respect to the reEining mechanism in the reiiner, it is recognized that the fibrous material is defibered when the fibrous material is brought into contact with the edges of the ribs, and -the defibered fibers are cut and/or compressed by the edges of the rotating ribs.
Also, it is recognized that, during the refining process the defibered fibers travel from the feed end zone to the discharge end zone through the grooves. That is, the function of the grooves is merely recognized as a path ~or the defibered fibers. For example, Goncharov, Bumazh Pro. No. 5, 12-14(1971), discloses that, when an unbleached sulfite pulp is refined with a disc type refiner, a very strong force is applied onto a part of a rib from a tip thereof to a level of 2.5 or 3 mm distant from the tip.
That is, when the refining operation is carried out under ordinary conditions, the force applied to the tip part of the rib is about 35 kg/cm2. This value of the force corresponds to about 13 times an average value of the force per unit area, cm2, applied to the entire outer area of the rib.
That is, the refining effect is attained mainly by the tip end portion of the rib, and the tip end portion is worn away during the refining process.
However, van der Akker (Fundamentals of Papermaking Fibres, Trans~ of the Symposium held at Cambridge, September, 1957, pages 435 through 446) states that about 99.9% of the energy applied to a refiner is spend for wearing away the ribs and converted to heat, and only about ~.1% of the , ~ . .
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' ~ :
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applied energy is utilized to refine the fibrous material~
It is known that the specific power consurnption in the operation of the refining process for refining chemical pulp is about 200 to 800 kWh/T, the specific power consump-tion for producing mechanical pulp from a refiner mechanicalpulp (RMP) is about 1400 to 1800 kWh/T and that from a thermomechanical pulp (T~P) is about 2000 kWh/T or more.
That is, the power consumption necessary for refining -the fibrous ma-terial by using a conventional refiner is very large. Accordingly, it is strongly desirable to enhance the efficiency of the refiner, so as to decrease the consumption of enexgy necessary for refining the fibrous material.
In the field of various types of refiners, it is believed that the depth of the grooves in the pulp refining surface should be at least 4 mm, because a depth of less than 4 mm results in a poor flow of the ~ibrous material between the pulp refining surfaces under an ordinary pressure. For example, P. J. Leider and J. Rihs, Tappi, Vol. 60, No. 9tl977), pages 98 through 102, state that the decrease in the depth of the groove causes the throughput of the fibrous material to decrease and that, when the depth of the grooves is l/8 inch labout 3.2 mm), no flow of the fibrous material occurs. In order to force the fibrous matexial to flow through the groove having a depth less than 4 mm, it is necessary to increase the pressure applied to the fibrous mateial. The increase in the pressure results in an increase in the consumption of : -- . - . . . . . . :
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energy for refining the fibrous material.
However, grooves having a depth of 4 mm or more, cause a portion of the fibrous material fed into the refiner to ~e accumulated in the grooves. The accumulated fibrous material forms a thick ma-t which is fixed unmovably in the groove. The mat acts as a force absor~er when the fibrous material is exposed to the refining action of the pulp refining surfaces. Therefore, the formation of the mats in the grooves causes the efficiency of the refining process to decrease.
U.S. Patent 3,745,645 discloses a method for fabricat-ing and operating a pair of relatively rotatable elemen-ts having ribs and grooves formed between the ribs. The height of the ribs (the depth of the grooves) is in a range of from about 1.5 to about 5.0 times the width of the ribs at the tips thereof. The grooves are partly filled with a plastic filler material. When the tips of the ribs wear down during the refining process, the height of the filler material is reduced, so as to restore the unfilled por-tion of the grooves substantially to the original depth thereof. This U.S. patent discloses grooves having a depth of 12 mm and partly filled with the filler material having a height of 8 mm, so as to leave a 4 mm free space at the top of the grooves. That is, in the refiner of this U.S. patent, since the depth of the grooves filled with the filler material is 4 mm, the grooves cannot prevent the formation of the thick mat of the fibrous material. In other words, the refiner of the U.S.
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patent cannot decrease -the comsumption of energ~ for the refining process.
SUMMARY OF THE INVENl'ION
An object of the present invention is to provide a pulp refining element for the use in a pulp refiner, which element is effective for causing -the refiner to opera-te with a high efficiency and wit:h a low consumption of energy.
Another object of the present invention is to provide a pulp refining element for the use in a pulp refiner, which element is effective for producing a enhanced quality of pulp.
The above-mentioned objects can be a-ttained by the refining element of the present invention, which element has a pulp refining surface having a feed end zone thereof to which a fibrous material is fed and a discharge end zone thereof from which the refined pulp is discharged, the pulp refining surface being provided with a number of grooves extending from the feed end zone to the discharge end zone of the pulp refining surface and a number of ribs defining the grooves therebetween, and which element is characterized in that the bottom of at least a portion of the grooves, the portion being located in the discharge end zone of the pulp refining surface, is covered with a layer of a synthetic polymer resin in such a manner that the outer surface of the synthetic polymer resin layer in a groove is O to 3 mm distant : from the level of the tips of the ribs defining the groove ..
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therebetween toward -the bottom.
In the pulp refining element, it is important that the bottoms of at least por-tions of the grooves located in the discharge end zone of the pulp refining surEace be 5 covered with a layer of a synthetic polymer resin. Also, it is important that the distance from the outer surface of the synthetic polymer resin layer in a groove to the level of the tips of the ribs defining the groo~e there-between, that is, the depth of a free space above the synthetic polymer resin layer in a groove, be in a range of from 0 to 3 mm.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 is fragmentary plan view of an embodiment of the pulp refining surface of the element of the present invention for use in a disc type refiner;
Fig. 2 is a fragmentary perspective view of an embodiment of the pulp refinin~3 element of the present invention for use in a disc type refiner;
Fig. 3 is a cross-sectional view of a pair of pulp refining elements of the present invention for use in a ; conical type refiner;
Fig. 4 is a graph showing a relation between a weight percent of a fraction of a refined pulp remaining on a 24 mesh screen and an unscreened freeness of the ,~ 25 refined pulp;
Fig. 5 is a graph showing a relation between a breakiny length of a refined pulp and a screened freeness of the refined pulp;
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Fig. 6 is a yraph showing a relation between a tear factor of a refined pulp and a screened freeness of the refined pulp;
Fig. 7 is a graph showing a relation between a breaking length of a refined pulp and a specific power consumption in the production of the refined pulp;
Fig. 8 is a graph showing a relation between a scattering coefficiert of a refined pulp and a specific power consumption in the production of the xefined pulp;
Fig. 9 is a graph showing a relation between a -specific power consumption in the production of a refined pulp and an unscreened freeness of the refined pulp;
Fig. 1~ is a graph showing a breaking length of another refined pulp and a specific power consump-tion in the production of the refined pulp, and;
Fig. 11 is a graph showing a scattering coefficient of another refined pulp and a specific power consumption in the production of the refined pulp.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Fig. 1, a pulp refining element usable for a disc type refiner has a pulp refinlng surface 1.
The pulp refining surface 1 contains a feed end zone 2 to which a fibrous material is fed, a discharge end zone 3 from which the resultant refined pulp is discharged, and a middle zone 4 through which the fibrous material travels from the feed end zone 2 to the discharge end zone 3. The pulp refinin~ surface 1 is provided with a number of grooves 5 extending from the feed end zone 2 to the discharge - - .
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end zone 3 through the middle zone ~, and a number of ribs 6 deEining the grooves 5 therebetween.
Referring to Fig. 2, in a discharge end zone oE a pulp refining surface 1 of an element for the use in a disc type refiner, a number of grooves 5 defined by a number of ribs 6, are filled with a synthetic polymer resin. That is, the bottom of each groove 5 is covered with a layer 7 of the synthetic polymer resin.
In a conical type refiner, as illustrated in Fig. 3, a conical rotor 11 has a conical outside surface and a shell 12 has a conical inside surface. Each of the conical outside surface of the rotor 11 and the conical inside surface of the shell 12 is provided with a number of grooves 5, and a number of ribs 6 defining the grooves 5 therebetween. The bottom of each groove is covered with a layer 7 of a synthetic polymer resin.
~iIn the pulp refining element of the present invention, the bottoms o~ the grooves located in at least the discharge end zone of the pulp refining surface/ are each covered with a layer of a synthetic polymer resin. That is, the bottoms of all grooves in the pulp refining surface may be covered with the synthetic polymer resin layers. ~lso, only the bottoms of the grooves located in the discharge end zone may be covered with the synthetic polymer resin layers. Furthermore, the bottoms of the grooves located in the discharge end zone and at least a portion of the ~`~mlddle zone, and/or the feed end zone, may be covered with the syn~thetlc polymer resin~layers.
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The synthetic polymer rPsin usable ~or the present invention is not limited to a special type of polymer resin. That is, the synthetic: polymer resin may be selected from the group consisting of synthetic thermo-plastic polymer resi.ns and synthetic thermosetting polymerresins.
The thermoplastic polymer may be selected from -the group consisting of polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, polypropylene, poly-amides, polycarbonates, polyacetal, polyethersulfones,polyesters, polyphenyleneoxide, modified polyphenyleneoxide, polyimides, polyamideimide acrylonitrile-butadiene-styrene terpolymers, acrylic ester polymers, methacrylic ester polymers, polymethylpentene, polysulfone, polyphenylene sulfide, styrene-maleic anhydride-acrylic ester terpolymers and polytetrafluoroethylene. ~!lore preferable theromplastic polymers for the present invention are polyamides, for example, nylon 11 and nylon 66, polyethylene, especially, high density polyethylene, polypropylene, poly carbonate, polymethylpentene, polysulfones, polyesters, polyphenylene sulfide, polyphenyleneoxide, modified polyphenylene oxides, for example, a blend of poiyphenylene oxides with polystyrene.
The thermosettlng polymer may be selected from the group consisting of phenol resins, diallylphthalate resins, unsaturated polyester resins, alkid resins, epoxy resins, silicone resins, polyurethane resins, melamine resins and uFea resins. More preferable thermosetting . .
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polymers for the present invention are diallylph-thalate resins and epoxy resins.
The synthetic polymer resin layer may contain a large number of pores having a size of 200 microns or less. The pores may be either connected to each other or be independent from each other.
The synthetic polymer r~esin layer may contains one or more additives, for example, pigments, anti-oxidants, fillers and stabilizers. It is preferable that -the synthetic polymer resin be selected from the resins having high resistances to abrasion and deterioration during the refining process, and capable of being easily placed and solidified in the grooves, and readily cut in the preparation of the resin layer~
Moreover, the synthetic polymer resin layer may contain abrasive particles dispersed in at least the outer surface portion of the the synthetic polymer resin layer.
The abrasive particles are effective for promoting the defibering action of the pulp refining surface on the fibrous material and for decreasing the specific power consumption of the refining process.
For example~ when a fibrous material having a ; pulp consistency of 15% is refined by a refiner, it was found that the pressure applied to the surfaces of the grooves is in a range of from 1 to 4 kg/cm2. The surface of the synthetic polymer resin layer containing the abrasive particles can effectively defiber the fibrous -material, even under the above-mentioned low pressure of , ... , - , .. . . ~ , - -' . . ' : . : . - : ' ..
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from 1 to 4 kg/cm2.
The abrasive particles may be selected ~rom the group consistin~ of fine particles of alumina, sil:icon carbide, boron carbide, steel, chromium oxide, iron oxide, garnet, emery siliceous sand, cement, glass and ceramics.
The abrasive particles preferably have an average size of from 50 to 600 microns, and are preferably used in an amount of from 30 to 90% by we:ight.
~ he layer of the synthetic polymer resin may be formed in any conventional methods. For example, a powdered or pelletized thermoplastic polymer resin is placed in the grooves, and mel-ted at an elevated tempera-ture higher than the melting point of the polymer resin, and then, cooled to room temperature, so as to solidify the layers of the polymer resin melt in situ in the grooves. Otherwise, a melt of the thermoplastic polymer resin is poured into the grooves and, then, solidified in situ. In the case where a thermosetting resins is used, a liquid or powdered thermosetting resin precursor is placed into the grooves and heated to an elevated temperature, so as to thermoset the resin precursor in the grooves.
In the case where the abrasive particles are used, the abrasive particles may be uniforml~ mixed with the entire amount of the synthetic polymer resin. Otherwise, the resin layer containing the abrasive particles may be formed in such a manner that a lower half portion of the resin layer is made of a polymer resin containing no abrasive particles and an upper half portion of the resin , - : . ,. --: .
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layer is formed by a mixture of the polymer resin and the abrasive particles.
For example, a resin layer containing the abrasive particles ~ay be prepared by placing a mixture of 7 parts by weight of silicon carbide particles, having a grain size of 60, and 3 parts by weight of a powdered poly-carbonate, in the grooves, pressing the layers of the mixture so as to make the layer of the mixture dense~ and sintering the layer of the mi~ture at a temperature of 235C.
The bottom of the groove is covered with the synthetic polymer resin layer in such a manner that the outer surface of the synthetic polymer resin layer in each groove is 0 to 3 mm, preferably, 0 to 2.5 mm, more preferably, 0.5 to
2.5 mm, distant from the level of the tips of the ribs defining the groove therebetwe~en toward the bottom. In other words, the depth of a free space above the synthetic polymer resin layer in each groove should be in a range of from 0 to 3 mm, preferably, 0 to 2.5 mm, more preferably, 0.5 to 2.5 mm.
It the synthetic polymer resin layer projects outward over the level of the tips of the ribs, this resin layer will hinder the refining action of the ribs. Also, if the distance between the outer surface of the resin layer and the level of the tips of the ribs is more than
It the synthetic polymer resin layer projects outward over the level of the tips of the ribs, this resin layer will hinder the refining action of the ribs. Also, if the distance between the outer surface of the resin layer and the level of the tips of the ribs is more than
3 mm, the decrease in the specific power consump-tion in the refining process will be poor.
The thickness of the synthetic polymer resin layer , :. ' : . . : - ': : ......... : ' , ' '~ ': ~
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- lG -ls no-t limited to a special range of value. However, the thickness of the synthetic polymer resin layer is preferably at least 1.0 mm, more preferably, in a ranye of from 1.5 to 4.0 mm. The outer surface of the synthetic polymer resin layer is either smooth or slightly rough and either flat or slightly concave or convex. In the case of a rough, concave or convex outer surface of the resin layer, the distance between a mean level of the outer surface and the level of the tips of the ribs should be in a range of from 0 to 3 mm. Also, the outer surface of the resin layer may be entirely or partly sloped in such a manner that the the closer to the discharge end of the pulp refining surface, the smaller the distance between the outer surface of the resin layer and the level of the tips of the ribs. In this case, in the grooves located in at least the discharge end zone, t:he largest distance between the outer surface of the resin layer and the level of the tips of the ribs should be in the range of Erom ~ to 3 mm.
The pulp refining element of the present invention can be used in any of the disc type refiners, selected from a single disc refiner, double disc refiner, floating disc refiner, conical type refiner and drum type refiner.
The pulp refining element of -the present invention can be utilized to refine a fibrous mateiral selected from wood chips; mechanically, thermally and/or chemically pretreated wood chips; mechanical pulp, such as ground wood pulp, refiner mechanical pulp and thermomechanical pulp; high yield pulps, such as chemiground pulp and .
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semichemical pulp; bleached or unbleached chemical pulp, such as ~raf-t pulp, sulfite pulp and soda pulp; oxyyen-pulped and bleache~ pulp, and; secondary fiber pulp. The pulp refining element of the presen-t invention can be utilized for refining non-ligno-cellulosic fibrous material, such as inorganic fiber material, synthetic fiber material and synthetic pulp.
Usually, the fibrous material is fed in the form of an aqueous suspension to the refiner. The pulp refining element of the present invention is effec-tive for refining the fibrous material in any content in the aqueous suspen-sion. That is, the content of the fibrous material in the aqueous suspension may be at a low level of less than 6%
by weihgt, a middle level of from 6 to 15% by weight, or a high level of more than 15%, by weight.
The features and advanta,ges o~ the pulp refining element of the present invention are explained in more detail in the following examples.
Examples 1 through 3_and Com~arison-Example 1 In each of the Examples 1, 2 and 3 and Comparison Example 1, a pulp refining plate, type 17804, which is a trademark of a pulp refining element made by SPRAUT WALDRON
COMPANY, and which is used in a 12 inch single disc refiner, was used. The pulp refining plate had a number of grooves having a width of 3 mm in the middle zone and 4 mm in the discharge end zone and a depth of 3.8 mm, and ribs each having a width of 3.1 mm in the middle zone and 3.8 mm in the discharge end zone. The grooves were filled with a : ~ .
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powdered nylon 11, so that the dep-th of each free space formed above the nylon 11 layer in each groove became zero (Exarnple 1), 1 mm (Example 2), 2 mm (Example 3) or 3.8 mm (Comparison Example 1).
The resultant pulp refining plate was placed in a 12 inch single disc refiner made by KUMAGAYA RIKI KOGYO
K. K., Japan.
An aqueous suspension of 6% or 15% by weight of a refiner mechanical pulp was sub~ected to a refining process by using the above-mentioned refiner.
The specific power consumption of the refining process, the breaking length, tear factor and scattering coefficient of the resultant pulp are shown in Figs. 4 through 8.
Fig. 4 shows relationships between the unscreened freenesses and the weight percent of fractions remaining on a 24 mesh screen, of the refined pulps of Examples 1 through 3 and Comparison Example 1, when the content of the refiner mechanical pulp was 6% by weight. In view of Fig. 4, it is clear that the weight percents of the fractions on the 2~ mesh screen of the refined pulps obtained by using the pulp refining elements of the present invention are larger than that obtained by using another pulp refining element which falls outside of the scope of the present invention.
Fig. 5 shows the relationships between the screened freenesses and the breaking lengths of the refined pulps of Examples 1 through 3 and Comparison Example 1, when the -' :; : ~ , ' - lg -concent o~ the refiner mechanical pulp was 6% by weight.
In view o~ Fig. 5, it is clear that -the breaking lenyths of the refined pulps o~ Example 1 through 3 are larger than that of Comparison Example 1, when the unscreened freenesses of the refined pulps are the same.
Fig. 6 shows a relationship between a screened freeness and a tear factor of the refined pulp of each of Example 1 through 3 and Comparison Example 1, when -the content of the refiner mechanical pulp was 6% by weight.
It is clear from Fig. 6 that the tear fac-tors of the refined pulps of Examples 1 through 3 are larger than that of Comparison Example 1, when the screenecl freenesses of the refined pulps are the same.
Fig. 7 shows a relationship between a specific power consumption of a refining process and a breaking length of a refined pulp of each! of Examples 1 through 3 and Comparison Example 1, when the content of the refiner mechanical pulp was 15~ by weight. In view of Fig. 7, it is evident that the breaking lengths oE the refined pulps of Examples 1 through 3 are larger than that of Comparison Example 1, when the specific power consumptions of the refining processes of all the exampls and comparison example are the same. Also, it is evident that the specifc power consumptions o~ the refining processes of Examples 1 through 3 are smaller than that of Comparison Example 1, when the breaking lengths of the resultant refined pulps of all the examples and comparison example are the same.
Fig. 8 shows a relationship between a specific ~: :
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power consumption of the refining process and a scattering coefficient of the refined pulp o:E each of Examples 1 through 3 and Comparison Example 1, when the content of the refiner mechanical pulp in the aqueous suspension was - 5 15~ by weigh-t. In view of Fi.g. 8, it is clear that the scattering coefficients of the refined pulps of Examples 1 through 3 are larger than that of Comparison Example 1, when all the specific power consumptions of the refining processes of the examples and comparison example are the same. Also, it is clear that the specific power consumpti.ons of the refining proceses of Examples 1, 2 and 3 are smaller than that of Comparison Example 1, when all the scattering coefficients of the refined pulps of the examples and comparison example are the same.
The same procedures as those mentioned above were repeated, except that the nylon 11 was replaced with polypropylene. The results were similar to those mentioned above.
Examples 4 and_5 In Example 4, procedures identical to those described in Example 2 were repeated, except that the nylon 11 was : replaced with polycarbonate and the content of the refiner ; mechanical pulp in the aqueous suspension was 15~ by weight. The polycarbonate layer was sintered at a temper-25 ature of 235''C for 40 minutes.
In Example 5, procedures identical to those described : in Example 4 were carried out, except that the polyca--bonate was replaced with a mixture of 7 parts by weight of silicon .
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carbide particles having a grain size of 60 and 3 parts by weiyht of polycarbonate.
Fig. 9 shows a relationship of the unscreened freeness of the refined pulp and the specific power consump-tion of the refining process of each of Examples ~ and 5.
In view of Fig. 9, it is clear that the specific power consumption of a refining process for producing a refined pulp having an unscreened freeness in Example 5, is about 2/3 times that for producing a refined pulp having the same unscreened freeness as that in Example 5 and Example ~.
Fig. 10 shows a relationship between a specific power consumption of a refining process and a breaking length of a refined pulp of each of Examples 4 and 5. In view of Fig. 10, it is clear that the abrasive particles in the resin layer are effec-tive for decreasing the specific power consumption of the refining process and for increasing the breaking length of the resultant refined pulp.
Fig. 11 shows a relationship between a specific power consumption o~ a refining process and a scattering coefficient of a refined pulp of each of Examples 4 and S.
In view of Fig. 11, it is evident that the abrasive particles in the resin layer are effective for increasing the scatter-ing coefficient of the resultant refined pulp.
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The thickness of the synthetic polymer resin layer , :. ' : . . : - ': : ......... : ' , ' '~ ': ~
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- lG -ls no-t limited to a special range of value. However, the thickness of the synthetic polymer resin layer is preferably at least 1.0 mm, more preferably, in a ranye of from 1.5 to 4.0 mm. The outer surface of the synthetic polymer resin layer is either smooth or slightly rough and either flat or slightly concave or convex. In the case of a rough, concave or convex outer surface of the resin layer, the distance between a mean level of the outer surface and the level of the tips of the ribs should be in a range of from 0 to 3 mm. Also, the outer surface of the resin layer may be entirely or partly sloped in such a manner that the the closer to the discharge end of the pulp refining surface, the smaller the distance between the outer surface of the resin layer and the level of the tips of the ribs. In this case, in the grooves located in at least the discharge end zone, t:he largest distance between the outer surface of the resin layer and the level of the tips of the ribs should be in the range of Erom ~ to 3 mm.
The pulp refining element of the present invention can be used in any of the disc type refiners, selected from a single disc refiner, double disc refiner, floating disc refiner, conical type refiner and drum type refiner.
The pulp refining element of -the present invention can be utilized to refine a fibrous mateiral selected from wood chips; mechanically, thermally and/or chemically pretreated wood chips; mechanical pulp, such as ground wood pulp, refiner mechanical pulp and thermomechanical pulp; high yield pulps, such as chemiground pulp and .
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semichemical pulp; bleached or unbleached chemical pulp, such as ~raf-t pulp, sulfite pulp and soda pulp; oxyyen-pulped and bleache~ pulp, and; secondary fiber pulp. The pulp refining element of the presen-t invention can be utilized for refining non-ligno-cellulosic fibrous material, such as inorganic fiber material, synthetic fiber material and synthetic pulp.
Usually, the fibrous material is fed in the form of an aqueous suspension to the refiner. The pulp refining element of the present invention is effec-tive for refining the fibrous material in any content in the aqueous suspen-sion. That is, the content of the fibrous material in the aqueous suspension may be at a low level of less than 6%
by weihgt, a middle level of from 6 to 15% by weight, or a high level of more than 15%, by weight.
The features and advanta,ges o~ the pulp refining element of the present invention are explained in more detail in the following examples.
Examples 1 through 3_and Com~arison-Example 1 In each of the Examples 1, 2 and 3 and Comparison Example 1, a pulp refining plate, type 17804, which is a trademark of a pulp refining element made by SPRAUT WALDRON
COMPANY, and which is used in a 12 inch single disc refiner, was used. The pulp refining plate had a number of grooves having a width of 3 mm in the middle zone and 4 mm in the discharge end zone and a depth of 3.8 mm, and ribs each having a width of 3.1 mm in the middle zone and 3.8 mm in the discharge end zone. The grooves were filled with a : ~ .
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powdered nylon 11, so that the dep-th of each free space formed above the nylon 11 layer in each groove became zero (Exarnple 1), 1 mm (Example 2), 2 mm (Example 3) or 3.8 mm (Comparison Example 1).
The resultant pulp refining plate was placed in a 12 inch single disc refiner made by KUMAGAYA RIKI KOGYO
K. K., Japan.
An aqueous suspension of 6% or 15% by weight of a refiner mechanical pulp was sub~ected to a refining process by using the above-mentioned refiner.
The specific power consumption of the refining process, the breaking length, tear factor and scattering coefficient of the resultant pulp are shown in Figs. 4 through 8.
Fig. 4 shows relationships between the unscreened freenesses and the weight percent of fractions remaining on a 24 mesh screen, of the refined pulps of Examples 1 through 3 and Comparison Example 1, when the content of the refiner mechanical pulp was 6% by weight. In view of Fig. 4, it is clear that the weight percents of the fractions on the 2~ mesh screen of the refined pulps obtained by using the pulp refining elements of the present invention are larger than that obtained by using another pulp refining element which falls outside of the scope of the present invention.
Fig. 5 shows the relationships between the screened freenesses and the breaking lengths of the refined pulps of Examples 1 through 3 and Comparison Example 1, when the -' :; : ~ , ' - lg -concent o~ the refiner mechanical pulp was 6% by weight.
In view o~ Fig. 5, it is clear that -the breaking lenyths of the refined pulps o~ Example 1 through 3 are larger than that of Comparison Example 1, when the unscreened freenesses of the refined pulps are the same.
Fig. 6 shows a relationship between a screened freeness and a tear factor of the refined pulp of each of Example 1 through 3 and Comparison Example 1, when -the content of the refiner mechanical pulp was 6% by weight.
It is clear from Fig. 6 that the tear fac-tors of the refined pulps of Examples 1 through 3 are larger than that of Comparison Example 1, when the screenecl freenesses of the refined pulps are the same.
Fig. 7 shows a relationship between a specific power consumption of a refining process and a breaking length of a refined pulp of each! of Examples 1 through 3 and Comparison Example 1, when the content of the refiner mechanical pulp was 15~ by weight. In view of Fig. 7, it is evident that the breaking lengths oE the refined pulps of Examples 1 through 3 are larger than that of Comparison Example 1, when the specific power consumptions of the refining processes of all the exampls and comparison example are the same. Also, it is evident that the specifc power consumptions o~ the refining processes of Examples 1 through 3 are smaller than that of Comparison Example 1, when the breaking lengths of the resultant refined pulps of all the examples and comparison example are the same.
Fig. 8 shows a relationship between a specific ~: :
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power consumption of the refining process and a scattering coefficient of the refined pulp o:E each of Examples 1 through 3 and Comparison Example 1, when the content of the refiner mechanical pulp in the aqueous suspension was - 5 15~ by weigh-t. In view of Fi.g. 8, it is clear that the scattering coefficients of the refined pulps of Examples 1 through 3 are larger than that of Comparison Example 1, when all the specific power consumptions of the refining processes of the examples and comparison example are the same. Also, it is clear that the specific power consumpti.ons of the refining proceses of Examples 1, 2 and 3 are smaller than that of Comparison Example 1, when all the scattering coefficients of the refined pulps of the examples and comparison example are the same.
The same procedures as those mentioned above were repeated, except that the nylon 11 was replaced with polypropylene. The results were similar to those mentioned above.
Examples 4 and_5 In Example 4, procedures identical to those described in Example 2 were repeated, except that the nylon 11 was : replaced with polycarbonate and the content of the refiner ; mechanical pulp in the aqueous suspension was 15~ by weight. The polycarbonate layer was sintered at a temper-25 ature of 235''C for 40 minutes.
In Example 5, procedures identical to those described : in Example 4 were carried out, except that the polyca--bonate was replaced with a mixture of 7 parts by weight of silicon .
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carbide particles having a grain size of 60 and 3 parts by weiyht of polycarbonate.
Fig. 9 shows a relationship of the unscreened freeness of the refined pulp and the specific power consump-tion of the refining process of each of Examples ~ and 5.
In view of Fig. 9, it is clear that the specific power consumption of a refining process for producing a refined pulp having an unscreened freeness in Example 5, is about 2/3 times that for producing a refined pulp having the same unscreened freeness as that in Example 5 and Example ~.
Fig. 10 shows a relationship between a specific power consumption of a refining process and a breaking length of a refined pulp of each of Examples 4 and 5. In view of Fig. 10, it is clear that the abrasive particles in the resin layer are effec-tive for decreasing the specific power consumption of the refining process and for increasing the breaking length of the resultant refined pulp.
Fig. 11 shows a relationship between a specific power consumption o~ a refining process and a scattering coefficient of a refined pulp of each of Examples 4 and S.
In view of Fig. 11, it is evident that the abrasive particles in the resin layer are effective for increasing the scatter-ing coefficient of the resultant refined pulp.
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Claims (11)
1. A pulp refining element for use in a pulp refiner, which element has a pulp refining surface having a feed end zone thereof to which a fibrous material is fed and a discharge end zone thereof from which the refined pulp is discharged, said pulp refining surface being provided with a number of grooves extending from said feed end zone to said discharge end zone of the pulp refining surface and a number of ribs defining the groove therebetween, and which element is characterized in that the bottom of at least a portion of said grooves, said portion being located in the discharge end zone of said pulp refining surface, is covered with a layer of a synthetic poly-mer resin in such a manner that the outer surface of said synthetic polymer resin layer in a groove is 0 to 3 mm distant from the level or the tips of the ribs defining the groove therebetween toward said bottom.
2. A pulp refining element as claimed in claim 1, wherein the thickness of said synthetic polymer resin layer is at least 1.0 mm.
3. A pulp refining element as claimed in claim 2, wherein said thickness of said synthetic polymer resin layer is in a range of from 1.5 to 4.0 mm.
4. A pulp refining element as claimed in claim 1, wherein said synthetic polymer resin layer comprises at least one thermoplastic polymer.
5. A pulp refining element as claimed in claim 4, wherein said thermoplastic polymer is selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, polystyrene, polyethylene, polypropylene, poly-amides, polycarbonates, polyacetal, polyethersulfones, polyesters, polyphenyleneoxide, modified polyphenyleneoxide, polyimides, polyamideimide, acrylonitrile-butadiene-styrene polymers, acrylic ester polymers, methacrylic ester polymers, polymethylpentene, polysulfones, polyphenylene sulfide, styrene-maleic anhydride-acrylic ester terpolymers and polytetrafluoroethylene.
6. A pulp refining element as claimed in claim 1, wherein said synthetic polymer resins layer comprises at least one thermosetting polymer.
7. A pulp refining element as claimed in claim 6, wherein said thermosetting polymer is selected from the group consisting of phenol resins, diallylphthalate resins, unsaturated polyester resins, alkid resins, epoxy resins, silicone resins, polyurethane resins, melamine resins and urea resins.
8. A pulp refining element as claimed in claim 1, wherein said synthetic polymer resin layer contains abrasive particles dispersed in a matrix consisting of said synthetic polymer resin.
9. A pulp refining element as claimed in claim 8, wherein said abrasive particles are dispersed in the outer surface portion of said synthetic polymer resin layer.
10. A pulp refining element as claimed in claim 8, wherein said abrasive particles are in an amount of from 30 to 90% by weight.
11. A pulp refining element as claimed in claim 8, wherein said abrasive particles comprise alumina, silicon carbide, boron carbide, steel, chromium oxide, iron oxide, garnet, emery, siliceous sand, cement, glass and ceramics.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP101458/78 | 1978-08-22 | ||
| JP10145878A JPS5530425A (en) | 1978-08-22 | 1978-08-22 | Refiner element |
| JP101457/78 | 1978-08-22 | ||
| JP10145778A JPS5530424A (en) | 1978-08-22 | 1978-08-22 | Refiner element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1104856A true CA1104856A (en) | 1981-07-14 |
Family
ID=26442331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA333,851A Expired CA1104856A (en) | 1978-08-22 | 1979-08-15 | Pulp refining element |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1104856A (en) |
| FI (1) | FI65100B (en) |
| SE (1) | SE445234B (en) |
| SU (1) | SU965363A3 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1989006718A1 (en) * | 1988-01-14 | 1989-07-27 | Robert Arthur Olson | Method of refining hardwoods to produce paper pulp |
| US4966651A (en) * | 1988-01-14 | 1990-10-30 | P.H. Glatfelter Company | Method of paper making using an abrasive refiner for refining bleached thermochemical hardwood pulp |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007121956A1 (en) * | 2006-04-26 | 2007-11-01 | Teijin Aramid B.V. | Process for yarn or sliver refining |
| US7896276B2 (en) * | 2007-02-02 | 2011-03-01 | Andritz Inc. | Refiner plates with high-strength high-performance bars |
-
1979
- 1979-08-15 SE SE7906818A patent/SE445234B/en not_active IP Right Cessation
- 1979-08-15 CA CA333,851A patent/CA1104856A/en not_active Expired
- 1979-08-21 SU SU792806449A patent/SU965363A3/en active
- 1979-08-22 FI FI792607A patent/FI65100B/en not_active Application Discontinuation
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1989006718A1 (en) * | 1988-01-14 | 1989-07-27 | Robert Arthur Olson | Method of refining hardwoods to produce paper pulp |
| GB2228498A (en) * | 1988-01-14 | 1990-08-29 | Robert Arthur Olson | Method of refining hardwoods to produce paper pulp |
| US4966651A (en) * | 1988-01-14 | 1990-10-30 | P.H. Glatfelter Company | Method of paper making using an abrasive refiner for refining bleached thermochemical hardwood pulp |
| GB2228498B (en) * | 1988-01-14 | 1992-01-22 | Robert Arthur Olson | An improved method of paper making |
Also Published As
| Publication number | Publication date |
|---|---|
| FI792607A (en) | 1980-02-23 |
| SE7906818L (en) | 1980-02-23 |
| FI65100B (en) | 1983-11-30 |
| SU965363A3 (en) | 1982-10-07 |
| SE445234B (en) | 1986-06-09 |
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| MKEX | Expiry |