Dewatering of foam-laid and water-laid structures and the formed web properties

Lehmonen, Jani; Retulainen, Elias; Paltakari, Jouni; Kinnunen-Raudaskoski, Karita; Koponen, Antti

doi:10.1007/s10570-019-02842-x

Cited by 20 publications

(21 citation statements)

References 29 publications

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“…In this case, the flow dynamics are reminiscent of foam flow through a fibrous porous medium. The flow of foam in the filtered sheet was studied by Lehmonen et al [86] with a vacuum-assisted sheet former. Figure 10a shows the dewatering time in this device as a function of vacuum level for water-laid and foam-laid forming.…”

Section: Flow Of Foam In Real Geometriesmentioning

confidence: 99%

“…Dewatering of wet foams: (a) Dewatering time in vacuum-assisted sheet forming as a function of vacuum level for water-laid and foam-laid forming. [86] (b) Foam flow in a fibrous porous material is a combination effect of bulk foam viscosity and bubble distortion. [88] Reprinted from Ref.…”

Section: Mixing Effects On Generated Foam Structurementioning

confidence: 99%

“…[88] Reprinted from Ref. [86] under the terms of the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).…”

Section: Mixing Effects On Generated Foam Structurementioning

confidence: 99%

“…Moreover, for the sheets containing stiff CTMP fibers, the simulated permeability varied systematically with mean bubble size (recall Figure 28b) as shown in Figure 32b. Lehmonen et al [86] made both types of sheets with a vacuum-assisted sheet former and compared the dry-sheet properties. Figure 32c shows the Bendtsen air permeability of the sheets at different SDS dosages.…”

Section: Structural Effects On Transport Propertiesmentioning

confidence: 99%

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Foam forming of fiber products: a review

Hjelt

Ketoja

Kiiskinen

et al. 2021

Journal of Dispersion Science and Technology

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Aqueous foam can be used as a transfer medium to form lightweight materials from natural and man-made fibers together with other types of raw materials. This review discusses mechanisms that underlie the forming process and thus influence physical properties of formed fiber networks such as microporous structure, strength behavior, and transport properties. Homogeneous fiber materials can be formed from versatile raw materials, which makes the technology suitable for a vast range of product applications. An intriguing feature of the method is that the wet foam characteristics provide an additional tool to tailor the performance of the dried material. Understanding foam rheology and how that is affected by added fibers is important in developing the forming process. We introduce both fundamental foam properties and practical forming methods, and show how the material properties are affected by the foam-fiber interaction. The basic features of an industrial production process are also described. The potential material properties are compared against key requirements in typical product applications.

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Section: Flow Of Foam In Real Geometriesmentioning

confidence: 99%

Section: Mixing Effects On Generated Foam Structurementioning

confidence: 99%

“…[88] Reprinted from Ref. [86] under the terms of the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).…”

Section: Mixing Effects On Generated Foam Structurementioning

confidence: 99%

Section: Structural Effects On Transport Propertiesmentioning

confidence: 99%

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Foam forming of fiber products: a review

Hjelt

Ketoja

Kiiskinen

et al. 2021

Journal of Dispersion Science and Technology

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“…8,9 Recently, several laboratory and pilot-scale investigations of using foam in the forming of conventional paper and board grades have been reported, the results highlighting excellent sheet formation that foam forming produces. 10,11 Also, foam has enabled the use of higher fiber consistencies with wood fibers and mixes of staple and wood fibers. 12 Similar advantages of foam are expected also when foam laying is used for making nonwovens from staple fibers.…”

Section: Introductionmentioning

confidence: 99%

Dispersion of 24-mm staple fibers with foam

Asikainen

Saharinen

Koponen

2020

Journal of Engineered Fibers and Fabrics

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In addition to carding and airlaid processes, nonwovens are produced from staple fibers by a wet-laid process. A drawback of this process is the necessity to use very dilute fiber suspensions to avoid fiber entanglement and consequent poor fiber web uniformity. As a result, flow volumes are very high and process speeds are rather low compared to water forming used in the paper and board industry. A promising option for making nonwovens is foam laying. The bubbles in foam keep the fibers apart until the foam is removed, and much higher fiber weight consistencies can be used compared to traditional wet laying. A key challenge in foam forming of nonwovens is to obtain uniform dispersion of the fibers in the foam. In this work, we studied this with 24-mm staple fibers, and analyzed the homogeneity of the obtained foams by making fibrous sheets from them in a laboratory sheet mold. We found that dispersion was highly dependent on the mixing conditions, such as mixing time, foam air content, and fiber weight consistency. Remarkably, excellent fiber disintegration and uniform sheets were obtained without mechanical pre-treatment of staple fibers, with fiber consistencies as high as 0.3%. By comparison, conventional wet-laid processes typically operate with fiber consistencies lower than 0.05%. Thus, at an industrial scale, foam forming promises production of uniform webs from stable fibers with clearly lower water volumes and possibly also higher machine speeds compared to conventional wet-laid forming.

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Air‐laid and foam‐laid nonwoven composites: The effect of carrier medium on mechanical properties

Paunonen,

Keränen,

Kamppuri

2024

J of Applied Polymer Sci

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Thermoplastic nonwoven composites were produced with the air‐laying and foam‐forming processes from cellulosic and plastic fibers. The two raw material combinations were (1) PP/PE (fiber length 3 mm), PP/PE (12 mm), fluff pulp fibers (2 mm) and (2) PP/PE (3 mm), fluff pulp fibers, viscose (10 mm). After forming, the fibrous sheets (400 gsm) were bonded with heat pressing (145°C). The effect of the carrier medium, air or aqueous foam, on the tensile and impact properties and sheet structure was explored. The air‐laids differed from the foam‐laids by sheet anisotropy, density, and the lack of an additional bonding regime between wood fibers due to the dry forming process. The PP/PE bonding fibers gave the air‐laids a good capacity to elongate compared to the foam‐laids. The advantage was lost when nonbonding viscose was added. The impact strength was dependent on the PP/PE dosage and the sheet density, rather than the moisture‐induced bonding between wood fibers. The changing long/short fiber ratios caused gradual shifts in sheet properties, usually a reduction in a mechanical property as the share of short fiber increased in the mix. Economic analysis revealed that increasing fluff content can reduce raw material costs, providing a possibility for cost optimization in total production costs.

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Dewatering of foam-laid and water-laid structures and the formed web properties

Cited by 20 publications

References 29 publications

Foam forming of fiber products: a review

Foam forming of fiber products: a review

Dispersion of 24-mm staple fibers with foam

Air‐laid and foam‐laid nonwoven composites: The effect of carrier medium on mechanical properties

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