Improved method for testing formaldehyde emission of core-board based on edge sealing control and uncertainty evaluation

Abstract

The invention discloses an improved core-board formaldehyde emission testing method based on edge sealing control and uncertainty evaluation, and belongs to the technical field of artificial board detection. Aiming at the problem that the edge sealing rule of the national standard GB / T 17657-2022 is not clear enough, the invention provides a zero end face edge sealing mode capable of stably reflecting the formaldehyde emission of the core-board, the edge sealing mode during sample detection is specified in detail, the edge sealing operation randomness is eliminated, and the reliability and comparability of a detection result are improved. On the basis, the invention develops a formaldehyde emission uncertainty evaluation method, the risk of a critical sample can be accurately prevented and controlled by introducing a parameter alpha and proposing the uncertainty of edge sealing influence contribution, and a'conditional qualification 'warning label is innovatively proposing, so that a consumer can be directly guided to safely select a product meeting the environmental protection requirement; and the indoor pollution risk is reduced from the source.

Description

Technical Field

[0001] This invention belongs to the field of engineered wood products testing technology, specifically involving an improved method for testing formaldehyde emission from plywood based on edge banding control and uncertainty assessment. Background Technology

[0002] According to the national standard GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels", 4.60 Formaldehyde Emission Determination—1m 3 The climate chamber method specifies that the specimen size for formaldehyde emission testing should be 1m in surface area. 2 The typical specimen dimensions are: length l = (500±5) mm; width b = (500±5) mm. Specific regulations are provided for specimen edge sealing: after balancing, formaldehyde-free aluminum tape is used for edge sealing, and the ratio of the unsealed length l to the specimen surface area is l / A = 1.5 m / m. 2 For a specimen with dimensions of 0.5m × 0.5m × plate thickness, the test requires two specimens, each with an unsealed edge length of l = 0.5m. 2 ×1.5m / m 2 =0.75m, meaning a 0.75m unsealed edge length is retained. However, the current national standard GB / T 17657-2022 does not explicitly specify the distribution ratio of this 0.75m unsealed edge length across the thickness surfaces in the length and width directions of the blockboard specimen. For engineered wood products with uniform structures, such as particleboard and fiberboard, the formaldehyde emission results are largely unaffected by the edge-sealing method. However, blockboard has a unique structure. It is an engineered wood product consisting of wood strips forming a core along the grain direction, glued to veneer or plywood on both sides. The glue density on the width side is much higher than that on the length side, making the unsealed edge surface a major channel for formaldehyde release.

[0003] The existing national standard GB / T 17657-2022, regarding edge sealing rules, is not sufficiently clear. The exposure of a 0.75m unsealed length on the specimen varies, leading to significant fluctuations in test results. Furthermore, the existing national standard testing methods do not consider the impact of edge sealing methods on test results, making it impossible to assess the confidence interval of the test results. Proposing more detailed testing standards can reduce result deviations caused by operational differences, allowing different testing personnel to obtain more consistent test results when operating according to national standards, thus making the test results more reliable and comparable. In addition, detailed testing standards enable consumers to better understand the formaldehyde release of engineered wood products, thereby choosing products that meet environmental protection requirements and reducing the harm to health caused by excessive formaldehyde, contributing to a safer indoor living environment for consumers. Summary of the Invention

[0004] In view of the above-mentioned prior art, the purpose of this invention is to provide an improved test method for formaldehyde emission of plywood based on edge banding control and uncertainty assessment. By precisely controlling the edge banding end face ratio and introducing an uncertainty calculation model, the test standard of GB / T 17657-2022 is refined, thereby improving the reliability and comparability of the test results.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an edge banding method for improving the stability of formaldehyde emission from plywood, the edge banding method being as follows:

[0007] According to the national standard GB / T 17657-2022, when testing the formaldehyde emission of plywood specimens, the edge banding ratio of the thickness surface in the width direction of the plywood specimen should be adjusted to 25%-100%. In practical applications, various edge banding methods can be obtained by adjusting the edge banding ratio of the thickness surface in the width direction of the plywood specimen.

[0008] For example, when the edge banding ratio of the thickness surface in the width direction is 25%, it is 1.5 end face edge banding; the 1.5 end face edge banding means that when testing the formaldehyde emission of plywood specimens according to the national standard GB / T 17657-2022, 1.5 thickness surfaces in the width direction of the plywood specimen are left unsealed, and the thickness surface in the length direction of the plywood specimen is edge-sealed.

[0009] When the edge banding ratio of the thickness surface in the width direction is 50%, it is called 1 end face edge banding; the 1 end face edge banding means that when testing the formaldehyde emission of plywood specimens according to the national standard GB / T 17657-2022, the plywood specimens are left unsealed on 1 width direction and 0.5 length direction thickness surfaces, and the remaining thickness surfaces are edge banded.

[0010] When the edge banding ratio of the thickness surface in the width direction is 75%, it is called 0.5 end face edge banding; the 0.5 end face edge banding means that when testing the formaldehyde emission of plywood specimens according to the national standard GB / T 17657-2022, 0.5 thickness surfaces in the width direction and 1 thickness surface in the length direction of the plywood specimen are left unsealed, and the remaining thickness surfaces are edge banded.

[0011] When the edge sealing ratio of the thickness surface in the width direction is 100%, it is called 0-end edge sealing; the 0-end edge sealing means that when testing the formaldehyde emission of plywood specimens according to the national standard GB / T 17657-2022, 1.5 thickness surfaces in the length direction of the plywood specimen are left unsealed, and the thickness surface in the width direction of the plywood specimen is sealed.

[0012] In this application, the term "end face" refers to the transverse section formed after the wooden board is cut and processed, which is a plane perpendicular to the direction of the wood grain. A blockboard specimen has two end faces, namely two thickness faces in the width direction.

[0013] Preferably, the 0-end-face edge sealing can completely eliminate the interference of the end-face glue seam and truly reflect the formaldehyde release characteristics of the board substrate. It is the only edge-sealing method that can stably reflect the formaldehyde release amount of blockboard.

[0014] The specifications of the blockboard are: length 2.44m × width 1.22m × board thickness; the specifications of the blockboard specimen are: length 0.5m × width 0.5m × board thickness.

[0015] In the second aspect of the present invention, a method for evaluating the uncertainty of formaldehyde release amount of the above-mentioned edge-sealing method is provided. The method for evaluating the uncertainty of formaldehyde release amount is specific for critical samples, and the method for evaluating the uncertainty of formaldehyde release amount includes the following steps:

[0016] (1) Critical sample triggering condition: 0.9L < Q0 ≤ 1.1L ………… (Ⅰ), where: Q0 is the measured value of formaldehyde release amount of 0-end-face edge sealing; L is the standard limit value of the formaldehyde release amount grade;

[0017] (2) Combined uncertainty model: Where: Q 1.5 is the measured value of formaldehyde release amount of 1.5-end-face edge sealing;

[0018] (3) Edge-sealing influence U (B) uncertainty component:

[0019] (4) Combined uncertainty: Where: U (Co) is the existing parameter formaldehyde collection process, U (Sc) is the existing parameter standard curve drawing, U (D) is the existing parameter formaldehyde concentration measurement, U (rep) is the existing parameter repeatability measurement.

[0020] In the third aspect of the present invention, a supporting warning label based on the above method for evaluating the uncertainty of formaldehyde release amount is provided, and the supporting warning label is a "conditionally qualified" warning label.

[0021] The method for generating the supporting warning label is: according to the combined uncertainty U C , obtain the expanded uncertainty U =

[0022] kU C Q0. When Q0 + U ≤ L, the product meets the quality requirements; when Q0 + U > L, generate a "conditionally qualified" warning label.

[0023] In the formula of the uncertainty U, k is the value at a 95% confidence probability, that is, k = 2.

[0024] Preferably, when Q0 > 1.1L or when Q0 ≤ 0.9L, the tested sample is a non-critical sample, and the above-mentioned uncertainty evaluation method for formaldehyde emission does not need to be used. Directly compare Q0 with the limit value L for determination: when Q0 < L, the product is qualified; when Q0 ≥ L, the product is unqualified.

[0025] When 0.9L < Q0 ≤ 1.1L, the detected sample is a critical sample, and the above-mentioned uncertainty evaluation method for formaldehyde emission needs to be used to determine whether the product is qualified: when Q0 + U ≤ L, the product is qualified and marked as "conditionally qualified"; when Q0 + U > L, a warning label is generated.

[0026] The edge-sealing method and the uncertainty evaluation method for formaldehyde emission proposed by the present invention are applicable not only to blockboards but also to blockboards with impregnated film-faced papers and other artificial boards based on blockboards.

[0027] Advantages of the present invention:

[0028] 1. Aiming at the problem that the edge-sealing rules in the national standard GB / T 17657-2022 are not clear enough, the present invention proposes a 0-end face edge-sealing method that can stably reflect the formaldehyde emission of blockboards, makes detailed regulations on the edge-sealing method during sample testing, eliminates the randomness of edge-sealing operations, and improves the reliability and comparability of test results.

[0029] 2. On the basis of making detailed regulations on the edge-sealing method, the present invention develops an uncertainty evaluation method for formaldehyde emission. By introducing the parameter α, the uncertainty of the contribution of edge-sealing is proposed, which can accurately prevent and control the risks of critical samples. And the innovative "conditionally qualified" warning label is proposed, which can directly guide consumers to safely select products that meet environmental protection requirements and reduce the indoor pollution risk from the source. Description of the drawings

[0030] Figure 1 It is a schematic diagram of different edge-sealing methods for blockboard specimens; among them, the vertical lines in the width direction of the blockboard specimens represent glue seams.

[0031] Figure 2 It is a schematic diagram of the blockboard structure. Detailed implementation manners

[0032] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanations of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0033] The specific embodiments of the present invention will be described in further detail below with reference to examples. The following detailed descriptions are illustrative and intended to provide further explanation of this application, rather than limiting the scope of the invention.

[0034] This invention relates to the formaldehyde emission detection method: Following the national standard GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels" 4.60 Formaldehyde Emission Determination—1m 3 Based on the climate chamber method, improvements are made to precisely control the edge sealing end face ratio and introduce an uncertainty calculation model to refine the testing standard of GB / T 17657-2022.

[0035] Example 1: Detection of the effect of edge sealing method on formaldehyde emission

[0036] Take four sets of plywood. Cut plywood specimens (2.44m long × 1.22m wide × thickness) into pieces 0.5m long × 0.5m wide × thickness, and label them as sample 1, sample 2, sample 3, and sample 4. Use formaldehyde-free aluminum tape, according to... Figure 1 The edge banding methods shown are 1.5mm, 1mm, 0.5mm, and 0mm, used to band the plywood specimens. After banding, the formaldehyde emission of the plywood samples with different edge banding methods was tested according to national standards. The test data are shown in Table 1.

[0037] Table 1: Formaldehyde emission test results for plywood with different edge banding methods

[0038]

[0039] Table 2: Comparison of the significant effects of different edge sealing methods on formaldehyde emission.

[0040]

[0041] Table 3: Sample Range Values

[0042]

[0043] Based on the test results, the average of the four data sets for all boards showed that the formaldehyde emission was lowest for the 0-side-band edge banding. The formaldehyde emission of all samples showed the following order: 1.5-side-band edge banding > 1-side-band edge banding > 0.5-side-band edge banding > 0-side-band edge banding (Table 1).

[0044] Table 2 shows that among all samples, the formaldehyde release from fully sealed (0-end face sealing) samples was significantly lower than that from 1.5-end face sealing (p<0.05). For 0.5-end face sealing, there was no significant difference between samples 2 and 4 and those with 1.5-end face sealing (p>0.05), which may be related to the core strip assembly process or the uniformity of adhesive application. It may also be related to the lower baseline formaldehyde release values ​​for samples 2 and 4. Therefore, because the adhesive seams are denser in the width direction and fewer in the length direction, and the national standard does not specify the exposure of the unsealed length (0.75m) on the sample, the number of exposed adhesive seams varies for the same sealing length, resulting in significant fluctuations in the test results. The higher the exposure ratio in the width direction, the greater the formaldehyde release.

[0045] As can be seen from the statistical results of the range values ​​in Table 3, when sealing the 0-end face, the detection data has high stability and low fluctuation.

[0046] Example 2: Formaldehyde Emission Test of Noncritical Samples

[0047] (1) Q0≤0.9L

[0048] Test subject: Plywood sample (E1 grade, standard limit L = 0.124 mg / m³) 3 )

[0049] Baseline test value (Q0): 0.08 mg / m³ 3 (0-end face sealing)

[0050] Critical threshold: Q0 ≤ (0.9L = 0.1116 mg / m³) 3 → No uncertainty assessment is required. Test data is output directly, and the sealing method is marked as 0-end sealing. The formaldehyde release of the sample is then deemed to be qualified.

[0051] (2) Q0 > 1.1L

[0052] Test subject: Plywood sample (E1 grade, standard limit L = 0.124 mg / m³) 3 )

[0053] Baseline test value (Q0): 0.57 mg / m³ 3 (0-end face sealing)

[0054] Critical threshold determination: Q0 > 1.1L (1.1L = 0.1364 mg / m³) 3 → No uncertainty assessment is required. Test data is output directly, and the sealing method is marked as 0 end face sealing. The formaldehyde release of the sample is determined to be unqualified.

[0055] Example 3: Critical Sample Formaldehyde Emission Test and Uncertainty Assessment

[0056] (1)Q0+U>L

[0057] Test subject: Plywood sample (E1 grade, standard limit L = 0.124 mg / m³) 3 )

[0058] Baseline test value (Q0): 0.112 mg / m³ 3 (0-end face sealing)

[0059] Critical threshold determination: (0.9L = 0.1116mg / m³) 3 ) <Q0≤(1.1L=0.1364mg / m 3 )…………(Ⅰ)→ Trigger uncertainty assessment.

[0060] The average formaldehyde release of samples from the same batch, when retaining a 1.5mm end face, was 0.130 mg / m³. 3 .

[0061] Right now:

[0062] Edge sealing affects U (B) Uncertainty components:

[0063] Sources of factors affecting the uncertainty in determining existing formaldehyde emission levels (U (Co) U (Sc) U (D) U (rep) The value of ).

[0064] Table 4: Determination of Factors Affecting Uncertainty Regarding Existing Formaldehyde Emission Rate

[0065] Sources of uncertainty relative uncertainty <![CDATA[Formaldehyde collection process U (Co) > 5.0×10-2 <![CDATA[Standard curve drawing U (Sc) > 2.4×10-2 <![CDATA[Formaldehyde concentration measurement U (D) > 3.8×10-3 <![CDATA[Repeated measurement U (rep) > 3.6×10-2

[0066]

[0067] At a 95% confidence probability and k = 2, the expanded uncertainty U = kU C Q0=2×0.116×0.112=0.026mg / m 3 That is: Q0 + U = 0.138 mg / m³ 3 >E1 level limit: 0.124 mg / m³ 3 The result does not meet the requirement of Q0+U≤L, and the product needs to be labeled with a "conditionally qualified" warning label, indicating that the end face must be sealed during use.

[0068] (2) Q0+U≤L

[0069] Test subject: Plywood sample (E1 grade, standard limit L = 0.124 mg / m³) 3 )

[0070] Basic test value (Q0): 0.113 mg / m 3 (0 end face edge sealing)

[0071] Critical determination: (0.9L = 0.1116 mg / m 3 ) < Q0 ≤ (1.1L = 0.1364 mg / m 3 )…………(Ⅰ) → Trigger uncertainty evaluation.

[0072] The average formaldehyde release amount of samples in the same batch when retaining 1.5 end faces is 0.119 mg / m 3 .

[0073] That is:

[0074] Edge sealing affects U (B) Uncertainty components:

[0075] Determine the sources of influencing factors for the uncertainty of the existing formaldehyde release amount (U (Co) , U (Sc) , U (D) , U (rep) ) values.

[0076] Table 5: Determination of the sources of influencing factors for the uncertainty of the existing formaldehyde release amount

[0077] Sources of uncertainty relative uncertainty <![CDATA[Formaldehyde collection process U (Co) > 1.5×10-2 <![CDATA[Standard curve drawing U (Sc) > 0.8×10-2 <![CDATA[Formaldehyde concentration measurement U (.D) > 1.2×10-3 <![CDATA[Repeated measurement U (rep) > 2.0×10-2

[0078]

[0079] At a 95% confidence probability and k = 2, the expanded uncertainty U = kU C Q0 = 2 × 0.040 × 0.113 = 0.009 mg / m 3 . That is: Q0 + U = 0.122 mg / m 3 <E1 grade limit 0.124 mg / m 3 , and this result meets Q0 + U ≤ L, and the product meets the standard requirements.

[0080] Example 4: Testing the formaldehyde release amount of impregnated veneer lumber and other wood-based panels with lumber core as the substrate

[0081] The detection method is the same as that of lumber core board.

[0082] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for edge banding to improve the stability of formaldehyde emission from plywood, characterized in that, The edge-sealing method is as follows: When detecting the formaldehyde emission of blockboard specimens according to the provisions of the national standard GB / T 17657-2022, adjust the edge-sealing ratio of the thickness surface in the width direction of the blockboard specimens to 25%-100%.

2. The edge sealing method according to claim 1, characterized in that, The edge-sealing method is as follows: When detecting the formaldehyde emission of blockboard specimens according to the provisions of the national standard GB / T 17657-2022, adjust the edge-sealing ratio of the thickness surface in the width direction of the blockboard specimens to 50%-100%.

3. The edge sealing method according to claim 1, characterized in that, The edge-sealing method is as follows: When detecting the formaldehyde emission of blockboard specimens according to the provisions of the national standard GB / T 17657-2022, adjust the edge-sealing ratio of the thickness surface in the width direction of the blockboard specimens to 100%.

4. The edge sealing method according to any one of claims 1-3, characterized in that, The specifications of the blockboard are: length 2.44m × width 1.22m × board thickness; the specifications of the blockboard specimens are: length 0.5m × width 0.5m × board thickness.

5. A method for evaluating the uncertainty of formaldehyde release in the sealing method described in claim 1, characterized in that, The formaldehyde emission uncertainty evaluation method is specific to critical samples, and the formaldehyde emission uncertainty evaluation method includes the following steps: (1) Critical sample trigger condition: 0.9L < Q0 ≤ 1.1L ………… (Ⅰ), where: Q0 is the test value of the formaldehyde emission with 0-end edge-sealing; L is the standard limit value of the formaldehyde emission grade. (2) Combined uncertainty model: Among them: Q 1.5 The formaldehyde emission value is for the 1.5mm end face edge sealing. (3) Edge sealing affects U (B) Uncertainty components: (4) Combined uncertainty: Among them: U (Co) For the existing parameters of the formaldehyde collection process, U (Sc) Plot the standard curve for the existing parameters, U (D) For the determination of formaldehyde concentration using existing parameters, U (rep) For repeatability measurements of existing parameters.

6. The method for assessing the uncertainty of formaldehyde release according to claim 5, characterized in that, In step (1), the 0-end edge-sealing means that when detecting the formaldehyde emission of blockboard specimens according to the provisions of the national standard GB / T 17657-2022, keep 1.5 thickness surfaces in the length direction of the blockboard specimens unsealed, and perform edge-sealing treatment on the thickness surface in the width direction of the blockboard specimens.

7. The method for assessing the uncertainty of formaldehyde release according to claim 5, characterized in that, In step (2), the 1.5-end edge-sealing means that when detecting the formaldehyde emission of blockboard specimens according to the provisions of the national standard GB / T 17657-2022, keep 1.5 thickness surfaces in the width direction of the blockboard specimens unsealed, and perform edge-sealing treatment on the thickness surface in the length direction of the blockboard specimens.

8. A supporting warning label for the formaldehyde emission uncertainty evaluation method according to claim 5, characterized in that, The supporting warning label is a "conditionally qualified" warning label.

9. The matching warning label according to claim 8, characterized in that, The method for generating the accompanying warning label is as follows: The combined uncertainty U generated according to claim 5 C The expanded uncertainty U = kU is obtained. C Q0, when Q0+U≤L, the product meets the quality requirements; when Q0+U>L, a "conditionally qualified" warning label is generated.

10. The matching warning label according to claim 9, characterized in that, In the uncertainty U formula, k is the value at a 95% confidence probability.

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