Method of quantifying the properties of paper

• US 5,680,321 A
• Filed: 05/18/1995
• Issued: 10/21/1997
• Est. Priority Date: 05/18/1994
• Status: Expired due to Term

• Current Assignee: EKA Chemicals AB (Nouryon BV)
• Original Assignee: Eka Nobel AB (Nouryon Coöperatief UA)
• Inventors: Renberg, Lars, Olsson, Ralf, Helmer, Ulla
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): KEMPER, MELANIE A
• Application Number:
  US08/443,667
• Time in Patent Office: 887 Days
• Field of Search: 364/499, 364/498, 364/497, 364/496, 364/471, 364/469.01, 364/469.02, 364/471.01, 364/471.02, 364/471.03, 162/49, 162/198, 210/745, 210/143
• US Class Current: 702/30
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 33/343 Paper pulp
• CPC Class Codes: G01N 33/346 Paper sheets

Abstract

A method for the quantification of the one or several of the physical properties selected from dry tensile strength, hydrophobicity, debonding energy, bursting strength, wettability and printability of pulp and/or paper which method comprises

(I) developing a calibration model by

(I.a) registering absorption, reflectance or emission spectra of reference samples of paper of known properties as defined above to develop learning sets;

(I.b) processing the spectral raw data, to reduce noise and adjust for drift and diffuse light scatter;

(I.c) performing a data analysis by applying chemometric techniques to the processed learning sets; and

(II) determining the unknown properties as defined above of pulp and/or paper by registering the absorption, reflectance or emission spectrum, in correspondence to (I.a), from the pulp and/or paper having unknown properties; processing the thereby obtained spectral raw data as according to (I.b); and applying the developed calibration model to the processed data.

Optionally, a data analysis step as according to (I.c) can also be applied to the processed spectral raw data from the paper having unknown properties.

Claims

1. A method for quantifying one or more physical properties of fluff pulp or paper treated with paper chemicals, which method comprises

(I) developing a calibration model by

(I.a) registering absorption, reflectance or emission spectral raw data of reference samples of paper of known properties to develop a learning set;

(I.b) processing the spectral raw data to reduce noise and adjust for drift and diffuse light scatter;

(I.c) performing a data analysis by applying chemometric techniques to the processed learning sets; and

(II) registering absorption, reflectance or emission spectral raw data of a sample of paper or fluff pulp having unknown properties;

processing the spectral raw data as according to (I.b); and

applying the developed calibration model on the processed spectral data in order to determine the unknown properties.

2. A method according to claim 1, wherein the recording of the absorption, reflectance or emission spectral raw data is performed in the wavelength of 200 nm to 400 μ

m.

3. A method according to claim 1, wherein the spectral data processing is performed using the Kubelka-Munk transform:

##EQU9## wherein R_ik is the apparent absorbance at the wavelength k, A_ik is the transformed absorbance at the wavelength k, and the index i represents the sample spectra available.

4. A method according to claim 1, wherein the spectral data processing is performed using the Multiplicative Scatter Correction:

##EQU10## wherein R_ik is the apparent absorbance at the wavelength k, A_ik is the transformed absorbance at the wavelength k, a_i is the least squares estimation of the intercept parameter, and b_i is the least squares estimation of the slope parameter, the index i representing the sample spectra available, and the index k representing the available wavelengths.

5. A method according to claim 1, wherein the spectral data processing is performed by use of the Fourier transformation.

6. A method according to claim 1, wherein the spectral data processing is performed by use of up to the fourth order derivatives.

7. A method according to claim 1, wherein the spectral data processing is performed by use of the Standard Normal Variate transformation.

8. A method of quality screening the properties of a paper using the method according to claim 1, wherein the data analysis is performed by the Discriminant Analysis.

9. A method according to claim 1, wherein the data analysis is performed by the use of the Multilinear Regression Analysis technique.

10. A method according to claim 1, wherein the data analysis is performed by the use of the Principal Component Analysis technique.

11. A method according to claim 1, wherein the the data analysis is performed by the use of the Principal Components Regression technique.

12. A method according to claim 1, wherein the the data analysis is performed by the use of the Partial Least Squares technique.

13. A method according to claim 1 for quantification of dry tensile strength.

14. A method according to claim 1 for quantification of hydrophobicity.

15. A method according to claim 1 for quantification of bursting strength and index.

16. A method according to claim 1 for quantification of debonding energy.

17. A method according to claim 1 for quantification of wettability.

18. A method according to claim 1 for quantification of printability.

19. A method for maintaining a process control program wherein the properties of a paper are quantified to detect any change thereof and provide control input, in order to assure optimum dosage levels for chemical additives, by the use of a method as defined in claim 1.

20. A method according to claim 1, wherein a data analysis of the process spectral data obtained from the fluff pulp or paper of the unknown property is performed by the use of the Multilinear Regression Analysis technique.

21. A method according to claim 1, wherein a data analysis of the processed spectral data obtained from the fluff pulp or paper of the unknown property is performed by the use of the Principal Component Analysis technique.

22. A method according to claim 1, wherein a data analysis of the processed spectral data obtained from the fluff pulp or paper of the unknown property is performed by the use of the Principal Components Regression technique.

23. A method according to claim 1, wherein a data analysis of the process spectral data obtained from the fluff pulp or paper of the unknown property is performed by the use of the Partial Least Squares technique.

24. A method according to claim 2, wherein the recording of the absorption, reflectance or emission spectral raw data is performed in the wavelength of 800 nm to 2500 nm.

25. A method according to claim 1, wherein one or more physical properties of paper containing wet strength agents, dry strength agents, starches, retention agents, sizing agents, or debonding agents are quantified.

26. A method according to claim 1, wherein the physical properties are selected from the group consisting of wet strength, dry tensile strength, hydrophobicity, debonding energy, bursting strength, wettability and printability.

27. A method according to claim 1, wherein the physical properties are selected from the group consisting of dry tensile strength, hydrophobicity, debonding energy, bursting strength, wettability and printability.

28. A method according to claim 1, wherein (I.c) the processed spectral data of the reference samples are transferred into latent variables based on principal component analysis, and chemometric techniques applied on the latent variables in order to find the mathematical expression of the calibration model;

and that in (II) the processed spectral data are transferred into latent variables as according to (I.c), and the developed calibration model applied on the latent variables in order to determine the unknown properties.