Paper bio-sizing agents

01Overview and value chain

Markers: [EC: EU PPWR / Effluent Guidelines | OECD: Industrial biotechnology | Regulator: EPA (USA), REACH (EU)]

Paper bio-sizing agents are wet-end and surface chemicals of biological origin — pine-gum rosin, fatty-acid-derived alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA), plus high-biomass polymer and transparentizing agents — that orient a hydrophobic film around fibres so paper and board resist water, oil and print bleed. The renewable-carbon position differs sharply by chemistry, and the distinction matters commercially: rosin is a pine-tree exudate and therefore bio-based by nature, AKD is built from C16–C18 plant and tallow fatty acids, but standard ASA is made from fossil isomerised C16–C18 olefins and is bio-based only in the newer maleated-vegetable-oil grades now reaching commercial supply (Kemira’s Fennosize MO 30 is 30% renewable, the balance conventional ASA). Rosin and AKD are thus the segments where renewable carbon is the default feedstock rather than a retrofit; ASA is mid-transition. The global paper sizing agent market is about USD 1.2 billion in 2024 on track to roughly USD 1.8 billion by 2033–34 at near 5% CAGR, with AKD sizing alone growing about 2.8% a year through 2035 as packaging and paperboard premiumise and printing grades decline. The structural pull is plastic-free, recyclable fibre packaging: a well-sized AKD or rosin program lets a corrugated or folding-carton line meet both 2-minute and UN 30-minute Cobb water-resistance targets with a single product, while the neutral-to-alkaline pH (7.0–9.0) of AKD/ASA cuts machine corrosion and effluent load versus acidic rosin sizing (pH 4.5–6.0).

Key directions of paper bio-sizing agents:

1. Rosin sizing (Rosin Sizing): the original bio-based acidic size — pine-gum rosin saponified or fortified into a soap or cationic emulsion, dosed at acid pH; the chemistry China’s gum-rosin industry (Guangxi) supplies globally, and the FCN/FDA-listed food-contact rosin-size family.
2. AKD sizing (Alkyl Ketene Dimer): a neutral/alkaline reactive size synthesised from fatty-acid dimers, the dominant grade for packaging and board, with stronger and more stable water resistance than rosin and full compatibility with recycled fibre and calcium-carbonate fillers.
3. ASA sizing (Alkenyl Succinic Anhydride): a fast-curing neutral size from isomerised C16–C18 olefins and maleic anhydride, dosed as a cationic emulsion on high-speed packaging machines, where deposit control at the wet end is the key engineering problem. Conventionally fossil-based; the bio route maleates high-oleic sunflower or rapeseed oil in place of the olefin.
4. Biomass surface & transparentizing agents (Biomass Surface/Transparentizing): high-biomass surface sizes and transparentizing/barrier agents — pine-rosin and polymer-based, up to 85% biomass content and food-contact certified — that displace plastic films in fibre packaging and make selected paper areas transparent.

Sectoral value chain

[rosin / fatty acid] ──> [synthesis] ──> [emulsification] ──> [wet-end / size press]
                              │                                       │
                    (AKD / ASA / rosin)                       (form + dry)
                              │                                       │
                              ▼                                       ▼
[Cobb-sized paper] <─── [sizing development] <────────── [recycle loop]

Value chain levels

Cross-cutting technologies of the sector:

• Cationic rosin emulsion preparation (Cationic Rosin Emulsion): fine-particle cationic rosin sizes that run at near-neutral pH for food-contact grades.
• AKD wax emulsification & cationic stabilization (AKD Emulsification): starch-stabilized AKD dispersions tuned for alkaline high-speed machines.
• Size-press surface sizing (Size-Press Surface Sizing): polymer/rosin surface sizes (e.g. POLYMARON) applied at the size press for printability and surface strength.

02US

The US sizing market is concentrated in packaging and fine-paper mills running neutral AKD and ASA programs, where the drive is deposit-free high-speed operation and food-contact compliance.

packaging sizing, ASA-deposit control, food-contact rosin

• Solenis imPress SB-798 / Hercon 620: a surface sizing agent that lets packaging mills hit both 2-minute and UN 30-minute Cobb targets with one product and eliminate surface ASA altogether, for a cleaner-running wet end and size press; Hercon covers rosin/AKD emulsion sizing.
• FDA FCN-listed rosin sizing: rosin-size families cleared under FDA Food Contact Notifications enable food-contact folding cartons and greaseproof grades.
• EPA Effluent Guidelines & TSCA: acidic-rosin effluent and wet-end discharge rules push high-speed US machines toward neutral AKD/ASA programs with lower corrosivity and effluent load.

03CN

China is the world’s largest gum-rosin (松香) producer — the Guangxi/Wuzhou forest-chemistry belt supplies a large share of global pine rosin — so bio-based rosin sizing is a domestic specialty, feeding the world’s largest recycled-containerboard sector.

gum-rosin feedstock, rosin-sizing production, recycled packaging

• Gum-rosin feedstock base: Guangxi and Guangdong forest-chemistry clusters supply the pine rosin that underpins domestic fortified-rosin and cationic-rosin sizing emulsions for recycled liner and corrugated.
• Domestic sizing-agent supply: Chinese paper-chemicals producers turn that rosin into rosin soap, ASA and AKD emulsions for the recycled-packaging sector, though the specialist merchant picture is fragmented across forest-chemical and paper-chemical firms rather than concentrated in one named supplier.
• MARA & GB standards: national food-contact and industrial chemical-additive standards frame the rosin modification and emulsifier chemistry permitted in paper-contact grades.

04EU

The EU leads on the regulatory pull — plastic-free, recyclable fibre packaging under the PPWR — that makes bio-based sizing a strategic input for corrugated, folding carton and beverage board.

plastic-free packaging, AKD wax supply, biomass-balanced sizing

• Kemira Fennosize MO 30 renewable ASA: the clearest bio-substitution in the sizing line — maleated high-oleic sunflower oil replaces the fossil olefin, shipped commercially as a 30% renewable / 70% conventional ASA blend, with a 40% blend tested and 100% run on a pilot paper machine; MSOHO viscosity is the constraint on going higher. Kemira also supplies AKD wax and neutral-sizing emulsions for packaging and board (it moved AKD wax pricing 10–20% in 2026 along the fatty-acid value chain).
• REACH & PPWR: REACH chemical registration and the Packaging & Packaging Waste Regulation’s recyclability requirement are the twin drivers displacing fossil sizing and plastic-film barriers with rosin/AKD sizing and biomass barrier agents.
• Biomass-balanced carbon accounting: European sizing-chemistry houses evidence renewable content through biomass-balanced and rosin-based sizing lines compatible with the fibre-recycling loop.

05Leading companies and research institutes

06Tech stack and innovations

The bio-sizing stack is built on rosin chemistry, fatty-acid-derived reactive sizing (AKD/ASA) and high-biomass surface and barrier agents.

1. Rosin sizing (Rosin Sizing):
   • pine-gum rosin saponified or fortified into a soap or cationic emulsion dosed at acidic pH 4.5–6.0.
   • case: Harima Chemicals’ biomass transparentizing and barrier agents built from pine-derived rosin; FDA FCN-listed rosin-size families for food contact.
2. AKD & ASA neutral sizing (AKD/ASA Neutral Sizing):
   • fatty-acid-derived AKD and (conventionally fossil) olefin-derived ASA reactive sizes run at neutral/alkaline pH 7.0–9.0 for stronger, more stable water resistance and lower corrosion; the renewable ASA route swaps the olefin for maleated high-oleic vegetable oil.
   • case: Kemira Fennosize MO 30 (30% renewable ASA from high-oleic sunflower oil) plus AKD wax and neutral-sizing emulsions for packaging; Solenis imPress SB-798 surface size eliminating surface ASA and its deposits, and Hercon 620 fine-paper surface sizing.
3. Biomass surface & transparentizing agents (Biomass Surface/Transparentizing):
   • polymer and rosin-based surface sizes and high-biomass barrier/transparentizing agents that displace plastic films and make selected paper areas transparent.
   • case: Harima water-based barrier-coating agents with up to 85% pine-based biomass, food-contact certified; Arakawa POLYMARON surface sizing agent for acid-to-neutral grades.

07Value chains and production pipelines

Industrial pipeline of a bio sizing program (TAPPI T 441 Cobb / ISO 535)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. Rosin / fatty-acid feed│ ───> │ 2. Sizing-agent synthesis │
└───────────────────────────┘      └───────────────────────────┘
                                                  │
                                                  ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Wet-end / size-press   │ <─── │ 3. Emulsification         │
└───────────────────────────┘      └───────────────────────────┘
               │
               ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Forming & drying       │ ───> │ 6. Cobb QC & effluent     │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: Rosin / fatty-acid feed

Pine-gum rosin from forest-chemistry supply and C16–C18 fatty acids from plant oils and tallow are received as the bio-based feedstock for the sizing agent.

Stage 2: Sizing-agent synthesis

Rosin is fortified or saponified into a rosin size; fatty acids are dimerized to AKD wax; isomerised olefins — or, in the renewable grades, maleated high-oleic vegetable oil — are reacted with maleic anhydride to ASA.

Stage 3: Emulsification

The sizing agent is emulsified to a fine cationic or anionic dispersion (~0.6–0.8 µm particle size) stabilized with starch or cationic polymer for stable wet-end and size-press application.

Stage 4: Wet-end / size-press dosing

The emulsion is dosed to the stock at the wet end or applied at the size press at neutral/alkaline pH, retained on the fibres by charge control.

Stage 5: Forming & drying

The treated furnish is formed and pressed, and the sizing film develops as the web passes the drying cylinders, orienting the hydrophobic alkyl or rosin chains toward the fibre surface.

Stage 6: Cobb QC & effluent

Water resistance is verified by Cobb testing (2-minute and UN 30-minute, TAPPI T 441 / ISO 535), and the lower-corrosivity neutral AKD/ASA effluent is managed under EPA Effluent Guidelines and REACH.