A kind of method of on-line non-destructive testing paper
Technical field
The invention relates to and set up the various performance prediction models of paper, and utilize the method for this model determination paper performance.
Background technology
Along with the raising of the requirement of paper and cardboard consumption, the paper industry prods quality is had higher requirement.Require paper performance that good consistance is arranged.Owing to market wood chip shortage, the pulp mill has to select different wood chips to come slurrying now, and this makes pulp quality not quietly, finally causes the finished product paper quality not quietly.If every performance of energy fast measuring finished product paper, and feed back to machine hand's skill, can stablize paper performance greatly, improve paper quality.At present to the various performance detection of paper, all need to get a certain amount of paper, deliver to quality testing department with its performance of corresponding Instrument measuring, this need spend the long time, and be destructive the measurement, can not online dynamic continuous detecting, can't reflect paper quality fast, timely feedback quality problem, the defective that exists analysis result to lag behind.These are unfavorable for the quick quality analysis of paper, enhance productivity, and are not suitable for the needs of modern production development.Therefore, current press for research a kind of fast, efficiently, new analyzing detecting method accurately.
Near infrared light (Near Infrared, NIR) be electromagnetic wave between visible light (VIS) and mid-infrared light (MIR), the wavelength coverage in the near infrared spectrum district of ASTM definition be 780~2526nm (12820~3959cm-1), again the near-infrared region is divided near infrared shortwave (780~1100nm) and near infrared long wave (1100~2526nm) two zones traditionally.Near-infrared spectrum analysis is that spectral measurement methods, the stoichiometry of infrared range (800-2500nm) nearly learns a skill, computer technology and basic test technology are intersected the modern analytical technique that combines, and is mainly used in the direct express-analysis of complex sample.During the near-infrared analysis complex sample, usually at first need the near infrared spectrum of sample and measurement parameters such as structures of samples, composition or character (recording) with the reference method of standard or approval, it is in addition related to adopt stoichiometry to learn a skill, and sets up calibration model to be measured; Calibration model by the mensuration and the application of unknown sample spectrum have been set up comes the fast prediction sample to be measured then.In recent years, to be applied to paper industry mainly be aspect the chemical composition mensuration of raw material near infrared technology and measure slurry Kappa number etc.
Show from the retrieval of China Intellectual Property Office's patent retrieval database, have only and utilize moisture and quantitative (CN 100501374C) infrared or near infrared technology mensuration paper, do not utilize near infrared online to measure patents such as paper whiteness, tensile strength, tear strength, pop strength, folding strength, smoothness, degree of sizing, transparency.In addition, report is arranged abroad, predict that the freedom of paper pulp, slurry are dense, tear index, tensile index and light scattering property by measuring the near infrared spectrogram of mechanical pulp production line spreading mass.And not about predict every index of paper by the near infrared light spectrogram of paper.
Summary of the invention
The method that the purpose of this invention is to provide a kind of non-destructive testing paper physical property based on near-infrared spectrum technique adopts near-infrared spectrum technique, compares with traditional means of testing, has fast, saves time, laborsaving and advantage such as can onlinely detect.
For achieving the above object, the technical solution used in the present invention step is as follows: a, a certain amount of representative outturn is got in not timing on the paper machine.B, employing near infrared spectrometer measuring samples are at 12000cm
-1-4000cm
-1Diffuse reflection spectrum or the projection spectrum, instrumental resolution is 2-128cm
-1, scanning 1-128 time on average becomes a spectroscopic data.C, the present conventional method of employing are measured every index of outturn.D, spectroscopic data is proofreaied and correct and pre-service, set up near-infrared spectrum analysis mathematical model between spectroscopic data and the pulpability, and it is deposited in the storer with modern multiple regression algorithm.E, with the paper of unknown sample set by step the method for b obtain its spectroscopic data, after the preprocess method of the spectroscopic data of unknown sample in steps d handled, spectrum characteristics is sent into calibration model, can measure the paper performance of unknown sample.Described paper performance comprises whiteness, tensile strength, tear strength, pop strength, folding strength, smoothness, degree of sizing, transparency etc.Accompanying drawing 1 shown device is set up the device of model for the present invention.
The present invention has the following advantages:
1. use the quantitative of near-infrared method on-line measurement paper, can realize the in good time detection of production line paper physical property.
2. realized the mensuration of multiple performance with an equipment, and whole process time is short, speed is fast, has improved work efficiency, has reduced equipment cost.
Embodiment
The present invention typically measures the example of fibrous material pulping yield and Kappa number method
(1) sample is selected; At first select acacia rachii 16 strains of the representative different strains and the different age of trees, get a disk every 1.5m, get 4-6 disk according to different every the trees of the height of tree along height of tree direction.From disk being got the wood particle of one 3cm * 3cm * 3cm, require the wood particle smooth surface clean and tidy, roughness is always.Get a certain amount of wood shavings, wear into wood powder.Remaining is processed into the wood chip of 20mm (length) * 10mm (wide) * 3mm (height).
(2) scanning spectrogram; In 4000cm-1-12000cm-1 spectrum district, scanning 64 times on average becomes a spectroscopic data, resolution 8cm with sample
-1, adopt universal stage to increase sampling area, gather the diffuse reflection spectrum of wood powder, wood shavings and wooden unit.
(3) pulpability; The wood chip that makes is carried out cooking test, measure pulping yield and slurry Kappa number with the method in the GB.
(4) spectrum pre-service; Obtain behind the sample spectrum spectroscopic data to be carried out the spectrum pre-service.
(5) foundation of model; Utilize the partial least square method in the multivariate analysis software, between the spectroscopic data that handled the pulpability of measuring and above-mentioned (4), set up the model of pulpability in above-mentioned (3).
(6) prediction pulpability; At first scan sample to be tested and obtain spectrogram, the measuring method that is adopted when obtaining their spectrogram, the measuring method that must be adopted with obtain reference sample the time is consistent, such as the method for sampling, rate, sweep time etc., parameter should be consistent respectively.The spectral signature parameter of unknown kind sample is sent into the pulpability that calibration model can be measured unknown sample.
Model by the method foundation, can predict the pulping yield and the Kappa number of plant material at short notice, the guidance of science can be provided for the directed genetic breeding of forest, also can instruct the pulp mill to change conditions of cooking according to the Kappa number of prediction according to different raw materials.
Description of drawings:
Fig. 1 is set up model near infrared detection system by the present invention.
Fig. 2 is the result who utilizes model determination paper tensile index of the present invention
Fig. 3 is the result who utilizes model determination paper whiteness of the present invention
Embodiment
Exemplary embodiments one of the present invention: the tensile index of measuring paper
(1) sample is selected; The paper that the representative raw material of at first selecting the different places of production (as Guangxi, Guangdong, Fujian), different strain (as Chinese white poplar, yearning between lovers wood, Eucalyptus, American-European poplar), different technology conditions (as different digestion times or temperature), difference to cut down trees season (as summer, winter) is produced.Generally get 50 parts at least, in practice can be according to the scope of application of calibration model, its quantity can constantly increase.This experiment is taken a sample 73 altogether.
(2) scanning spectrogram; In 4000cm-1-12000cm-1 spectrum district, is 8cm in resolution with sample
-1Down, scanning 64 times on average becomes a spectroscopic data.
(3) paper performance; Scanned the tensile index of spectrogram paper at experimental determination.
(4) spectrum pre-service; Obtain with eliminating constant offset spectroscopic data to be carried out the spectrum pre-service behind the sample spectrum.
(5) foundation of model; At 11995.6cm
-1-6098.1cm
-1And 5450.1cm
-1-4597.7cm
-1The spectrum district utilizes the partial least square method in the multivariate analysis software, between the spectroscopic data that handled the tensile index of measuring in above-mentioned (3) and above-mentioned (4), sets up the model of tensile index
(6) prediction tensile index; At first scan sample to be tested and obtain spectrogram, the measuring method that is adopted when obtaining their spectrogram, the measuring method that must be adopted with obtain reference sample the time is consistent, such as the method for sampling, rate, sweep time etc., parameter should be consistent respectively.The spectral signature parameter of unknown kind sample is sent into the tensile index that calibration model can be measured unknown sample.
By the model that the method is set up, can predict the tensile index of paper at short notice,
Exemplary embodiments two of the present invention: measure paper of whiteness
In the present embodiment, get the paper that has scanned spectrogram and measure its whiteness, spectrogram is carried out pre-service, select 11995.6cm-1-6098.1cm-1 and 5450.1cm-1-4246.7cm-1 spectrum district with first order derivative+vector normalization with the whiteness instrument.Additive method is identical with embodiment one.