Foam Control Agents for Paper and Pulp

Abstract

The present invention discloses a foam control agent and a method for controlling foam in paper or pulp production by using the foam control agent, wherein the foam control agent contains at least a branched alcohol.

Description

[0001] Embodiments are directed to foam control agents and methods of controlling foam for paper and pulp production, wherein the foam control agent comprises at least a branched alcohol. Background Art

[0002] In the paper and pulp industry, silicone-based foam control agents account for approximately one-third of the foam control market. Foam control agents are primarily used in the washing step of pulp processing to control foam generated by fatty acids in black liquor. Due to their low surface tension and unique chemistry, silicones are particularly suitable for this application. The silicone backbone resists degradation, resulting in longer persistence in these caustic systems, however, silicone-based foam control agents have deposition issues and provide lower knockdown performance.

[0003] For all of these reasons and others, there is a need for foam control agents and methods of controlling foam for pulp and paper. Summary of the invention

[0004] Embodiments are directed to foam control agents and methods of controlling foam for paper and pulp production, wherein the foam control agent comprises at least a branched alcohol. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Various embodiments are disclosed in the following detailed description and accompanying drawings:

[0006] Figure 1 This is a picture of the pump test components DETAILED DESCRIPTION

[0007] The present disclosure relates to foam control agents for paper and pulp production. The present disclosure details how branched alcohols unexpectedly show excellent foam control properties. The branched alcohols can be 2-alkyl-1-alkanols (also known as Guerbet alcohols), and are preferably 2-ethylhexanol (2-EH) and 2-propylheptanol (2-PH). These alcohols can be synthesized via aldol condensation of the corresponding aldehydes or by the Guerbet reaction of primary straight chain alcohols. Other production methods can also be used.

[0008] In the present invention, C9 to C12 beta-branched alcohols (C9-C12 Guerbet alcohols) were found to be surprisingly effective in reducing foam in black liquor for paper and pulp.Another benefit of branched alcohols is that they have good biodegradability.

[0009] The general structure of currently disclosed foam suppressors is as follows:

[0010]

[0011] wherein x is an integer from 2 to 8, and R is an alkyl group having 1 to 8 carbon atoms.

[0012] Foam control agents may also be described as 2-alkyl substituted alcohols consisting of C9-C12. These alcohols may be predominantly one isomer (>95 wt%) or a mixture of alcohols which may be produced by aldol condensation of a mixture of aldehydes or from a mixture of alcohols via a Guerbet reaction.

[0013] Preferred in some embodiments are C8-C32 Guerbet alcohols including 2-ethylhexanol and 2-propylheptanol, and mixtures of C8, C9, and C10 alcohols produced by the aldol condensation of butyraldehyde and valeraldehyde.

[0014] The concentration of the Guerbet alcohol in the formulated foam control agent ranges from 0.01% to 100%, preferably from 25% to 100% when used as an antifoam or defoamer. The Guerbet alcohol may be in the form of a solid or a liquid, with liquids being preferred. If the Guerbet alcohol is a solid, the material may be dissolved or dispersed in a solvent. The foam control agent may be an aqueous solution or an organic solvent-based solution. The dosage of the foam control agent for paper and pulp production varies between 0.01% and 5%, preferably in the range of 0.1% to 1% (50 ppm to 100 ppm).

[0015] Other foam control agents (e.g. random or block copolymers composed of ethylene oxide, propylene oxide and / or butylene oxide) or other hydrophobic materials (such as waxes, oils or silica) can also be added with the branched Guerbet alcohols. Siloxanes can be used with 2-alkyl alcohols. Surfactants, especially alkoxylates of alcohols, can also be used. The use of branched alcohols as foam control agents can be water-based or oil-based.

[0016] The novel foam control agent disclosed in the present invention can be in the form of a solid or a liquid. If it is a solid, the material can be dissolved or dispersed in a solvent before use as a foam control agent. The agent disclosed in the present invention is believed to work in the presence of all commonly used wastewater treatment processes.

[0017] Chemical agents can be used in antifoam or defoamer formulations. Antifoam formulations are obtained by mixtures of polyethylene glycols, esters, silicones, solvents, water and other chemicals that prevent foam formation at the gas-liquid interface of the gas bubbles. Other amphiphilic chemicals based on block copolymers can also be used. In the defoamer formulation, in addition to the products mentioned above, vegetable oils, mineral oils, waxes and other oily agents can also be used.

[0018] The optional surfactant or emulsifier included in the foam control agent is selected to improve the compatibility of the foam control agent with the raw materials or to form an emulsion with the branched alcohol composition. The amount of the optional surfactant or emulsifier is 0.1 wt % to 30 wt % of the branched alcohol composition.

[0019] The optional surfactant or emulsifier may be anionic, cationic or nonionic. Examples of suitable anionic surfactants or emulsifiers are alkali metal soaps, ammonium soaps and amine soaps; the fatty acid portion of such soaps preferably contains at least 10 carbon atoms. These soaps may also be formed "in situ"; in other words, the fatty acid may be added to the oil phase and the alkaline substance may be added to the water phase.

[0020] Other examples of suitable anionic surfactants or emulsifiers are alkali metal salts of alkyl-aryl sulfonic acids, sodium dialkyl sulfosuccinate, sulfated or sulfonated oils, such as sulfated castor oil; sulfonated tallow, and alkali metal salts of short-chain petroleum sulfonic acids.

[0021] Suitable cationic surfactants or emulsifiers are salts of long chain primary, secondary or tertiary amines, such as oleamide acetate, cetylamine acetate, didodecylamine lactate, aminoethyl-aminoethylstearamide acetate, dilauroyltriethylenetetramine diacetate, 1-aminoethyl-2-heptadecenylimidazolinium acetate; and quaternary ammonium salts, such as cetylpyridinium bromide, hexadecylethylmorpholinium chloride and diethyldi-dodecylammonium chloride.

[0022] Examples of suitable nonionic surfactants or emulsifiers are condensation products of higher fatty alcohols with ethylene oxide, such as the reaction product of oleyl alcohol with 10 ethylene oxide units; condensation products of alkylphenols with ethylene oxide, such as the reaction product of isooctylphenol with 12 ethylene oxide units; condensation products of higher fatty acid amides with 5 or more ethylene oxide units; polyethylene glycol esters of long-chain fatty acids, such as tetraethylene glycol monopalmitate, hexaethylene glycol monolaurate, nonanediol monostearate, nonanediol dioleate, tridecanediol monoarachidate, behenediol monobehenate; higher fatty acid esters of polyol moieties, such as sorbitan tristearate; higher polyol moieties of polyols, such as sorbitan tristearate; Ethylene oxide condensation products of fatty acid esters and their internal anhydrides (mannitol-anhydride, called mannose; sorbitol-anhydride, called sorbitan), such as glycerol monopalmitate reacted with 10 ethylene oxide molecules, pentaerythritol monooleate reacted with 12 ethylene oxide molecules, sorbitan monostearate reacted with 10 to 15 ethylene oxide molecules, mannose monopalmitate reacted with 10 to 15 ethylene oxide molecules; long-chain polyethylene glycol, in which one hydroxyl group is esterified with a higher fatty acid, and the other hydroxyl group is etherified with a low molecular alcohol, such as methoxy polyethylene glycol 550 monostearate (550 represents the average molecular weight of the polyethylene glycol ether). A combination of two or more of these surfactants can be used; for example, cations can be blended with nonions, or anions can be blended with nonions.

[0023] The foam control agent may also contain one or more additives. Examples of additives include ethylene oxide / propylene oxide block copolymers, butylene oxide / propylene oxide block copolymers, ethylene oxide / butylene oxide block copolymers, waxes or silicone-based materials. For other pulp and paper applications where surfactants cause foaming in the pulp production step, higher 2-alkyl substituted alcohols up to C32 may be used.

[0024] Example

[0025] Experiments to test the efficacy of the foam control agents disclosed herein and other foam control agents can be conducted as follows.

[0026] Material

[0027] Table 1: Raw materials used in the experiments

[0028]

[0029]

[0030] The Examples and Comparative Examples tested are shown in Table 2 below (the materials listed in Table 1 above are featured). The silicone antifoam was mixed with propylene glycol and then injected directly into the recycle stream using a positive displacement micropipette. The silicone emulsion was diluted in water and injected directly into the recycle stream using a positive displacement micropipette. To test the effect of propyl heptanol, it was injected directly into the recycle stream using a second micropipette, simultaneously with the silicone / propylene glycol mixture.

[0031] Table 2: Examples and Comparative Examples

[0032]

[0033]

[0034] Test Methodology

[0035] To test the foam control performance, a pump test was used. The pump test consisted of three components: a 2L clear jacketed glass open top glass column with a valve at the bottom. A battery heater that recirculated the silicone fluid through the jacket to maintain temperature. A centrifugal pump with its inlet connected to the bottom valve of the column and the outlet into the top of the open glass column to recirculate the foaming medium. Figure 1 is a picture of the pump test components.

[0036] To conduct a pump test with the above components, 800 mL of foaming medium (high, low foam or hardwood black liquor) was heated to 95°C in a 1L Erlenmeyer flask on a stirring hot plate. The top of the flask was loosely covered with a small lid to minimize evaporation. Once heated, the foaming medium was carefully poured into a 2L glass column preheated to 110°C. The foam suppressant was then loaded into a micropipette. The circulation pump was turned on and the foam was monitored until it reached 1700 mL in the column, and then the foam suppressant was injected directly into the circulation stream. The foam volume was monitored until the foam returned to the maximum 1700 mL level or ten minutes had passed, whichever came first.

[0037] result

[0038] As shown in Table 3 below, 0.5% (5000 ppm) 2-PH in high foaming black liquor had a significant improvement in foam knockdown compared to the silicone based foam control agent 3104. The 2-PH alcohol exhibited good persistence performance. Also shown in Table 3, 0.125% (1250 ppm) 2-PH in low foaming black liquor had better performance in knockdown performance and persistence performance similar to the baseline 3104. 2-EH alcohol comparative examples were also evaluated and as shown in Table 3, they were not as effective as 2-PH alcohol.

[0039] Table 3: Experimental results of single chemical as defoamer

[0040]

[0041]

[0042]

[0043] The mixtures of silicone 3073 and 2-PH mixture and the mixtures of ACP 1400 and 2-PH showed some surprisingly improved synergistic properties as shown in Table 4. Thus, the presence of 2-PH improved knockdown and persistence properties compared to the pure silicone foam control agent.

[0044] Table 4: Experimental results of foam control agent mixture

[0045]

[0046]

[0047]

Claims

1. A method for controlling foam in paper and pulp production by using a foam control agent, wherein the foam control agent comprises at least 2-propylheptanol, and wherein the use dosage of the foam control agent for paper and pulp production is in the range of 50 ppm to 100 ppm.

2. The method according to claim 1, wherein at least one other foam control agent or a hydrophobic material is added.

3. The method according to claim 1, wherein siloxane is also added.

4. The method according to claim 1, wherein the method is used in paper or pulp production.

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