WO1994007126A1 - A method and equipment for discerning inhomogeneity in the structure of paper - Google Patents
A method and equipment for discerning inhomogeneity in the structure of paper Download PDFInfo
- Publication number
- WO1994007126A1 WO1994007126A1 PCT/FI1993/000381 FI9300381W WO9407126A1 WO 1994007126 A1 WO1994007126 A1 WO 1994007126A1 FI 9300381 W FI9300381 W FI 9300381W WO 9407126 A1 WO9407126 A1 WO 9407126A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- paper
- sheet
- vacuum
- dry
- discerning
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 19
- 239000000126 substance Substances 0.000 claims abstract description 5
- 230000005855 radiation Effects 0.000 claims abstract description 3
- 238000001035 drying Methods 0.000 description 8
- 238000012360 testing method Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000013441 quality evaluation Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/34—Paper
- G01N33/346—Paper sheets
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/72—Investigating presence of flaws
Definitions
- the object of the invention is a method and equipment for discerning inhomogeneity, in which method a sheet of paper is examined on the basis of radiation directed towards it.
- the structure of the base of paper is formed in the wire section of the paper machine. There are always various unevennesses in the structure due to the operation of the wire section. These are measured by means of, among other methods, formation (small- scale base weight variation) and orientation (the average direction of the fibres of the paper) . Inhomogeneities in the structure of the paper appear as operational properties of the paper, causing problems in the further finishing of the paper and in its final use.
- Variation in the base weight of paper has been investigated by means of beta-radiation. Variation in the moisture content is then also present. Using present techniques, porosity and moisture must be measured as averages over large areas. Optical transmission gives a visual picture of the precise distribution of light penetrability. This does not necessarily correlate with beta-formation, especially in papers with additives.
- the aim of this invention is to create a new kind of method for discerning inhomogeneities in paper and the possibility of classifying examined paper samples on the basis of a new criteria.
- the characteristic features of the method in accordance with the invention are presented in the accompanying Patent Claim 1 and the characteristic features of corresponding equipment are presented in Patent Claim 4.
- the invention is to a large extent based on the observation that the inhomogeneities of paper appear indirectly.
- a vacuum is directed onto it to accelerate evaporation, which emphasizes possible temperature differences on the surface of the paper.
- the temperature distribution first of all indicates the distribution of the air penetrability of the paper, which further indicates the quantities actually under investigation such as, for example, local differences in base weight, porosity, and orientation. Even though these cannot be distinguished from one another by means of this method, it is in any event possible to classify the samples examined in a new way, which can form one part of the quality evaluation of paper.
- the sheet of paper 3 is placed on top of the vacuum box l, in which a vacuum of 3 - 20 kPa is created.
- the dry substance content of the paper is 40 - 50 %.
- the paper sample can be taken directly from the press. If the paper sample is dry, it is dampened to equilibrium moisture content e.g. between damp press-dry sheets of paper.
- the rate of drying of the paper at different places varies according to the local structure of the paper. Local unevennesses in drying are influenced by the structure of the paper, lumps of fibre, variations in porosity, unevenness in the distribution of fillers and fine substances, etc.. Due to these variations, the amount of water contained by the paper may vary locally. There may also be local variations in the ratio of free to bound water. Due to the aforementioned factors the rate of drying of the paper varies locally.
- thermograph 2 Due to different rates of drying, the surface temperature of the paper settles to a certain equilibrium temperature depending on the moisture content of the place in question. The development of temperature differences is now monitored during the drying process with the aid of thermograph 2. In tests carried out on newsprint temperature differences in the surface began to appear when the dry-substance content reached 70 % and were apparent until the paper was nearly dry. By means of the technique described it is possible to investigate inhomogenities in the structure of paper and local variations due to the them in the drying process of paper.
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Paper (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI924276A FI92438C (fi) | 1992-09-24 | 1992-09-24 | Menetelmä ja laitteisto paperin rakenteen epähomogeenisuuden havaitsemiseksi |
FI924276 | 1992-09-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1994007126A1 true WO1994007126A1 (en) | 1994-03-31 |
Family
ID=8535919
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI1993/000381 WO1994007126A1 (en) | 1992-09-24 | 1993-09-23 | A method and equipment for discerning inhomogeneity in the structure of paper |
Country Status (2)
Country | Link |
---|---|
FI (1) | FI92438C (fi) |
WO (1) | WO1994007126A1 (fi) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3483721A (en) * | 1966-12-30 | 1969-12-16 | Automation Ind Inc | Material tester |
US3494173A (en) * | 1967-10-20 | 1970-02-10 | Cons Paper Inc | Method and apparatus for testing printing paper for blistering |
US4246775A (en) * | 1979-06-08 | 1981-01-27 | Philip Morris Incorporated | Porosity measuring apparatus and perforating system using same |
US4602160A (en) * | 1983-09-28 | 1986-07-22 | Sentrol Systems Ltd. | Infrared constituent analyzer and control system |
US4823008A (en) * | 1987-11-05 | 1989-04-18 | Process Automation Business, Inc. | Apparatus and methods employing infrared absorption means to measure the moisture content of heavy grades of paper |
-
1992
- 1992-09-24 FI FI924276A patent/FI92438C/fi active
-
1993
- 1993-09-23 WO PCT/FI1993/000381 patent/WO1994007126A1/en active Application Filing
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3483721A (en) * | 1966-12-30 | 1969-12-16 | Automation Ind Inc | Material tester |
US3494173A (en) * | 1967-10-20 | 1970-02-10 | Cons Paper Inc | Method and apparatus for testing printing paper for blistering |
US4246775A (en) * | 1979-06-08 | 1981-01-27 | Philip Morris Incorporated | Porosity measuring apparatus and perforating system using same |
US4602160A (en) * | 1983-09-28 | 1986-07-22 | Sentrol Systems Ltd. | Infrared constituent analyzer and control system |
US4823008A (en) * | 1987-11-05 | 1989-04-18 | Process Automation Business, Inc. | Apparatus and methods employing infrared absorption means to measure the moisture content of heavy grades of paper |
Also Published As
Publication number | Publication date |
---|---|
FI924276A (fi) | 1994-03-25 |
FI924276A0 (fi) | 1992-09-24 |
FI92438C (fi) | 1994-11-10 |
FI92438B (fi) | 1994-07-29 |
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