Foam control agents for paper and pulp

Abstract

A foam control agent and a method of using the foam control agent to control foam for paper and pulp production, wherein the agent comprises at least a branched alcohol.

Description

Technical Field

[0001] Embodiments relate to foam control agents and methods for controlling foam in paper and pulp production, the agent including at least a branched alcohol.

[0002] Introduction In the paper and pulp industry, silicone-based foam control agents account for about one-third of the foam control market. The foam control agents are mainly used during the washing process of pulp processing to control the foam generated from fatty acids into the black liquor. Silicones are particularly suitable for this application due to their low surface tension and unique chemical properties. The siloxane backbone is resistant to decomposition, leading to longer persistence in these caustic systems, but silicone-based foam control agents have concerns about deposition and provide lower knockdown performance.

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

Summary of the Invention

[0004] Embodiments relate to foam control agents and methods for controlling foam in paper and pulp production, the agent including at least a branched alcohol.

Brief Description of the Drawings

[0005] Various embodiments are disclosed in the following "Modes for Carrying Out the Invention" and the accompanying drawings. [Figure 1] It is a diagram of pump test components.

Modes for Carrying Out the Invention

[0006] This disclosure relates to foam control agents for paper and pulp production. This disclosure details how, unexpectedly, branched alcohols have been shown to have excellent foam control properties. The branched alcohols may be 2-alkyl-1-alkanols (also known as Guerbet alcohols), preferably 2-ethylhexanol (2-EH) and 2-propylheptanol (2-PH). These alcohols can be synthesized via aldol condensation of the corresponding aldehyde or from the Guerbet reaction of primary linear alcohols. Other production methods may also be available.

[0007] In this invention, C9-C12β-branched alcohols (C9-C12 Guerbet alcohols) have been found to be remarkably effective in reducing foam in black liquor for paper and pulp. Another advantage of branched alcohols is their excellent biodegradability.

[0008] The general structure of the currently disclosed antifoaming agent is as follows:

[0009] [ka] In the formula, x is an integer between 2 and 8, and R is an alkyl group having 1 to 8 carbon atoms.

[0010] The foam control agent may also be described as comprising a C9-C12 2-alkyl-substituted alcohol. The alcohol may be primarily a single isomer (>95% by weight), or a mixture of alcohols which may be generated by aldol condensation of a mixture of aldehydes, or generated from a mixture of alcohols via a Guerbet reaction.

[0011] In some embodiments, C8-C32 Guerbet alcohols containing 2-ethylhexanol and 2-propylheptanol, as well as mixtures of C8, C9, and C10 alcohols generated from the aldol condensation of butyraldehyde and varrealdehyde, are preferred.

[0012] The concentration of Guerbet alcohol in the formulated foam control agent is in the range of 0.01% to 100%, preferably 25% to 100%, when used as an antifoaming or defoaming agent. Guerbet alcohol may be in solid or liquid form, with liquid being preferred. If 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 amount of the foam control agent used for paper and pulp production varies from 0.01% to 5%, preferably in the range of 0.1% to 1% (50 to 100 ppm).

[0013] Other foam control agents (e.g., copolymers, random or block, composed of ethylene oxide, propylene oxide, and / or butylene oxide), or other hydrophobic materials such as waxes, oils, or silica may also be added with the branched Guerbet alcohol(s). Silicones can be used in combination with 2-alkyl alcohols. Surfactants, particularly alcohol alkoxylates, can also be used. The use of branched alcohols as foam control agents may be aqueous or oil-based.

[0014] The novel foam control agents currently disclosed may be in solid or liquid form. If solid, the material may be dissolved or dispersed in a solvent before being used as a foam control agent. The currently disclosed agents are expected to work in the presence of all commonly used wastewater treatment processes.

[0015] Chemical agents can be used in both antifoaming and defoaming formulations. Antifoaming formulations are obtained by a mixture of polyglycols, esters, silicones, solvents, water, and other chemicals at the gas-liquid interface of bubbles that prevent foam formation. Other amphiphilic chemicals of block copolymer systems can also be used. In defoaming formulations, in addition to the above products, vegetable oils, mineral oils, waxes, and other oily agents can be used.

[0016] Any surfactant or emulsifier contained in the foam control agent is selected to improve the compatibility of the foam control agent with the raw materials or to be suitable for forming an emulsion with the branched alcohol composition. The surfactant or emulsifier is present in an amount ranging from 0.1 to 30% by weight of the branched alcohol composition.

[0017] Any surfactant or emulsifier may be anionic, cationic, or nonionic. Suitable examples of anionic surfactants or emulsifiers are alkali metals, ammonium, and amine soaps, the fatty acid portion of such soaps preferably contains at least 10 carbon atoms. Soaps can also be formed "in situ," in other words, by adding fatty acids to the oil phase and alkaline materials to the aqueous phase.

[0018] Other suitable anionic surfactants or emulsifiers include alkali metal salts of alkyl-aryl sulfonic acids, sodium dialkyl sulfosuccinate, sulfated or sulfonated oils, such as sulfated castor oil, sulfonated animal fat, and alkali salts of short-chain petroleum sulfonic acids.

[0019] Suitable cationic surfactants or emulsifiers include salts of long-chain primary, secondary, or tertiary amines such as oleylamide acetate, cetylamine acetate, didodecylamine lactate, aminoethyl-aminoethyl stearamide acetate, dilauroyltriethylenetetramine diacetate, and 1-aminoethyl-2-heptadecenylimidazoline acetate; as well as quaternary salts such as cetylpyridinium bromide, hexadecylethylmorpholinium chloride, and diethyldidodecylammonium chloride.

[0020] Examples of suitable nonionic surfactants or emulsifiers include condensation products of higher aliphatic alcohols and ethylene oxide, such as the reaction product of oleyl alcohol and 10 ethylene oxide units; condensation products of alkylphenols and ethylene oxide, such as the reaction product of isooctylphenol and 12 ethylene oxide units; condensation products of higher fatty acid amides and 5 or more ethylene oxide units; polyethylene glycol esters of long-chain fatty acids such as tetraethylene glycol monopalmitate, hexaethylene glycol monolaurate, nonaethylene glycol monostearate, nonaethylene glycol dioleate, tridecaethylene glycol monoarachidate, tricosaethylene glycol monobehenate, and tricosaethylene glycol dibehenate; and polyhydric alcohols such as sorbitan tristearate. These are long-chain polyglycols in which one hydroxyl group is esterified with a higher fatty acid and the other hydroxyl groups are etherified with a low molecular weight alcohol, such as partially higher fatty acid esters, ethylene oxide condensation products of polyhydric alcohol partially higher fatty acid esters, and intramolecular anhydrides of glycerol monopalmitate reacted with 10 molecules of ethylene oxide, pentaerythritol monooleate reacted with 12 molecules of ethylene oxide, sorbitan monostearate reacted with 10-15 molecules of ethylene oxide, mannitane monopalmitate reacted with 10-15 molecules of ethylene oxide (mannitol anhydride called mannitane, sorbitol anhydride called sorbitan), and methoxypolyethylene glycol monostearate 550 (550 represents the average molecular weight of polyglycol ethers). Two or more combinations of these surfactants may be used; for example, cationic surfactants may be blended with nonionic surfactants, or anionic surfactants may be blended with nonionic surfactants.

[0021] The brewing control agent may further 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 substances. For other pulp and paper applications where surfactants cause foaming in the pulp production process, higher 2-alkyl-substituted alcohols up to C32 can be used.

Examples

[0022] Experiments for testing the effectiveness of brewing control agents such as those of the present disclosure can be conducted as follows.

[0023] Materials

[0024]

Table 1

[0025] The tested examples and comparative examples are shown in Table 2 below (characterized by the raw materials listed in Table 1 above). The silicone defoamer was mixed with propylene glycol and then directly injected into the recirculation flow using a volumetric micropipette. The silicone emulsion was diluted with water and directly injected into the recirculation flow using a volumetric micropipette. To test the effect of propyl heptanol, it was directly injected into the recirculation flow with a second micropipette simultaneously with the silicone / propylene glycol mixture.

[0026]

Table 2

[0027] Test method A pump test was used to test the foam control performance. The pump test consisted of three components: a 2L transparent jacketed glass open-top glass column with a valve at the bottom; a cell heater to recirculate the silicone fluid through the jacket to maintain temperature; and a centrifugal pump with an inlet attached to the valve at the bottom of the column and an outlet entering the top of the open glass column to recirculate the foaming medium. Figure 1 shows a diagram of the pump test components.

[0028] To perform the pump test with the above components, 800 mL of foaming medium (high-foaming, low-foaming, or hardwood black sap) was heated to 95°C in a 1 L Erlenmeyer flask on a stirring hot plate. The top of the flask was loosely covered with a small cap to minimize evaporation. After heating, the foaming medium was carefully poured into a 2 L glass column preheated to 110°C. The defoaming agent was then packed into a micropipette. The recirculation pump was activated, and the foam was monitored until it reached 1700 mL in the column, after which the defoaming agent was injected directly into the recirculation flow. The amount of foam was monitored until the foam returned to the maximum level of 1700 mL, or after 10 minutes, whichever came first.

[0029] result As shown in Table 3 below, 0.5% (5000 ppm) 2-PH in highly foaming black liquor shows a significant improvement in foam knockdown compared to the silicone-based foam control agent 3104. This 2-PH alcohol exhibits good sustained performance. Furthermore, as shown in Table 3, 0.125% (1250 ppm) 2-PH in low-foaming black liquor shows better performance in terms of knockdown performance and sustained performance similar to benchmark 3104. As shown in Table 3, comparative examples of 2-EH alcohol were also evaluated, and they were not as effective as 2-PH alcohol.

[0030] [Table 3-1]

[0031] [Table 3-2]

[0032] As shown in Table 4, the mixtures of silicone 3073 and 2-PH, and the mixtures of ACP1400 and 2-PH, showed, somewhat surprisingly, improved synergistic performance. Therefore, the presence of 2-PH improves both knockdown performance and persistence performance compared to pure silicone foam control agents.

[0033] [Table 4-1]

[0034] [Table 4-2]

Claims

1. A method for controlling foam for paper and pulp production by using a foam-controlling agent, wherein the agent comprises at least 2-propylheptanol.

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

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

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

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