Alternatives to TOFA: a fatty acid feedstock selection framework

Choosing an alternative to TOFA resolves on three axes: acidity, rosin acid content and unsaturation. If you want no rosin acid, TOFA 185 (max 2%) is the target; if you tolerate it, rich distillate (total 20.4) or DTO (max 30%); if you want single-component unsaturation, oleic acid (C18:1 min 75.0%).

First the question: why do you want to switch?

The most frequently skipped step in a feedstock change is writing down the reason for it. In practice the real reason is usually one of three, and which one it is directly determines which alternative is even worth looking at.

• Specification mismatch: the current feedstock fails one parameter of the formulation (colour, rosin acid tolerance, unsaturation, unsaponifiable matter).
• Scale and packaging: the requirement does not fit an ISO tank load, or conversely bulk shipment is now needed.
• Documentation requirement: a buyer, an audit or a customer asks for a different identity or origin record for the feedstock.

If the reason is specification, the decision is made on technical axes. If the reason is scale, a different grade from the same family sometimes solves it with no chemical change at all. If the reason is documentation, the real cost of the change shows up in the quality file rather than in the lab. Conflating these three is the most common route to an unnecessary requalification.

The decision is made on three axes

Rather than memorising the differences product by product, it is enough to read three axes. They order the entire option set and determine where each product falls.

Axis 1: acidity

Acidity is what sets stoichiometry in esterification, saponification and neutralisation chemistry. Within the tall oil family the order is TOFA 185 at acid value min 185, TOFA 180 at min 180, rich distillate at a reported 178.5, DTO Mid-High at min 170 and DTO Industrial Grade at min 165. On the oleochemical side, Oleic Acid 75% sits at an acid value of 197-205 mg KOH/g, higher and narrower than anything in the tall oil family. Palm kernel oil (RBD) is not a fatty acid but an oil: it is defined by free fatty acid max 0.1% and is not used as a direct acid source.

Axis 2: rosin acid content

The second axis is the one that genuinely separates the alternatives. Rosin acid content is max 2% in TOFA 185 and max 3% in TOFA 180. In rich distillate, total rosin acids are reported at 20.4. In DTO Mid-High and DTO Premium it is max 30%, and in DTO Industrial Grade max 40%. Oleic acid and vegetable-derived feedstocks carry no rosin acid at all; there is no rosin fraction in them. If your formulation treats rosin acid as a defect you move down the axis; if it uses it as a contribution, you move up.

Axis 3: unsaturation

The third axis governs drying and oxidative crosslinking behaviour. Both TOFA 180 and TOFA 185 come with an iodine value of min 150. Oleic Acid 75% has an iodine value of min 90.0 g I2/100g, clearly lower, and its unsaturation is concentrated on a single double bond (C18:1 min 75.0%, C18:2 max 14.0%). Palm kernel oil (RBD) leaves the axis entirely at an iodine value of max 19. On rich distillate the profile concentrates on polyunsaturated rows: linoleic and its isomers 32.8 + 7.3, linolenic 6.2.

The option set in one table

The table below shows what each of the three axes amounts to for every option, together with what the move costs on the documentation side. Every row comes from the real specification of the relevant product:

The last row is deliberately without numbers. Synthetic and petrochemical-derived acids have no defined product row in this portfolio, so we state no specification value for them. What matters for the decision is not a number anyway but the categorical consequence: on that move, your renewable origin and by-product status argument disappears entirely.

What changes in your formulation when you switch?

The formulation impact of a feedstock change depends on how far you move on each of the three axes. Moves within the family are small; moves out of it are large.

1. TOFA 185 to TOFA 180: the acid value floor widens from 185 to 180, the rosin acid ceiling from 2% to 3% and the unsaponifiables ceiling from 4% to 6%. The iodine value floor (min 150) does not move. Recheck recipe stoichiometry against the acidity floor.
2. TOFA to rich distillate: acidity stays almost in place (178.5), but total rosin acids rise to 20.4. In systems that tolerate rosin acid this is a gain; in colour-sensitive systems, film colour must be reassessed.
3. TOFA to DTO: the rosin acid ceiling rises to max 30% or 40% and the acidity floor drops to min 170 or 165. This requires a serious recalculation of recipe ratios.
4. TOFA to oleic acid: acidity rises to 197-205 mg KOH/g, rosin acid goes to zero and the iodine value falls to min 90.0. Drying rate and crosslinking behaviour change, and low-temperature behaviour differs as well, with titre max 9.0 C and cloud point max 8.0 C.
5. TOFA to a vegetable oil: palm kernel oil (RBD), at iodine value max 19 and free fatty acid max 0.1%, is not an acid source. That move is not a substitution but a change of the process itself.

What changes in your documents when you switch?

Formulation impact is measurable and gets resolved in the lab. Documentation impact is frequently overlooked and costs time later. Within the family the chemical identity stays fixed: TOFA 180, TOFA 185 and rich distillate come with the same document set (KKDIK-registered, Turkish Safety Data Sheet, a certificate of analysis for every lot), and the TOFA grades are defined under the same CAS number (61790-12-3).

Once you leave the family the chemical identity changes, and that cascades through your file. Oleic Acid 75% carries CAS 112-80-1 and palm kernel oil (RBD) CAS 8023-79-8. A new CAS means a new Safety Data Sheet, a new qualification file and, where a recipe has been declared to a customer, a new notification. Your origin narrative changes too: tall oil is a by-product of kraft pulping, while vegetable-derived feedstocks come from a different feedstock pool.

• A move within the same CAS (between TOFA grades): the SDS stays the same, the CoA parameter lines change, the recipe is revalidated.
• A move within the family that keeps the identity stable (TOFA to rich distillate or DTO): the document set is the same, but your rosin acid and unsaponifiables tolerances must be updated in writing.
• A move out of the family (oleic acid, vegetable oil, synthetic acid): new CAS, new SDS, new qualification and, where required, customer notification.
• In every case: archive the per-lot certificate of analysis for the new feedstock from the first batch onward.

The selection flow, step by step

The flow below turns the three axes above into a decision order. At each step, if the answer is yes, the decision can be made without going further:

1. Does your formulation tolerate no rosin acid at all? If yes, TOFA 185 (max 2%); if there is some flexibility, TOFA 180 (max 3%).
2. Do you actually want rosin acid? If yes, rich distillate for a narrow target (total 20.4) or DTO for a wide window (max 30% or 40%).
3. Is drying and oxidative crosslinking critical? If yes, stay with the TOFA grades at iodine value min 150; oleic acid at min 90.0 serves this need less well.
4. Do you need a single-component, narrow unsaturation profile? If yes, Oleic Acid 75% (C18:1 min 75.0%, C18:2 max 14.0%).
5. Is low-temperature fluidity critical? Oleic acid is defined with titre max 9.0 C and cloud point max 8.0 C; on the TOFA side the storage condition is given as 20-40 C.
6. Is your requirement below one ISO tank load? If yes, rich distillate is also packed in IBC; TOFA 185 is ISO tank 20-22 MT net and TOFA 180 is ISO tank 20-24 MT net.
7. Do you need to preserve a renewable, by-product-derived feedstock statement? If yes, synthetic and petrochemical-derived options are eliminated.

The detail of the pairwise comparisons is outside the scope of this framework: TOFA against oleic acid, against distilled tall oil, against rosin acid and against vegetable fatty acids are each handled on their own pages. This page tells you which comparison to open; it does not repeat the comparison itself.