TECHNICAL FIELD

The present disclosure generally relates to a method for producing an epoxy resin. The disclosure relates particularly, though not exclusively, to a method for producing an epoxy resin comprising mixing tall oil pitch with at least one epoxidized vegetable oil.

BACKGROUND

This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

Crude tall oil (CTO) is a by-product of pine wood pulping (Kraft process) used by paper mills. The pulpwood is chipped and boiled with an alkali solution to produce black liquor and pulp. The water from the black liquor is evaporated and the black liquor soap is skimmed off and acidulated to make CTO. Tall oil pitch (TOP) is obtained as a bottom fraction in the fractional vacuum distillation of crude tall oil. TOP typically consists of fatty acids and resin acids, alcohol esters of fatty acids and resin acids, oligomers of fatty acids and resin acids, phytosterols, hydrocarbons and numerous other components. Often the produced TOP is incinerated at the site for producing energy.

Instead of incinerating tall oil pitch, tall oil pitch is used in variety of applications, such as an emulsifier in styrene-butene-rubber (SBR) polymerization for fluidity increasing, as emulsifier for asphalt, as a binder in cement and as a sizing reagent for paperboard.

However, there is still a need for new methods for upgrading tall oil pitch and uses of tall oil pitch.

SUMMARY

The appended claims define the scope of protection. Any examples and technical descriptions of apparatuses, products and/or methods in the description and/or drawings not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention. In a first aspect the present invention provides a method for producing an epoxy resin comprising mixing tall oil pitch, modified tall oil pitch or a mixture thereof and at least one epoxidized vegetable oil for producing a mixture comprising the tall oil pitch, modified tall oil pitch or a mixture thereof and the at least one epoxidized vegetable oil; and curing the mixture, preferably curing thermally the mixture.

In a second aspect the present invention provides an epoxy resin, wherein the epoxy resin comprises essentially at least one epoxidized vegetable oil cross-linked essentially with modified tall oil pitch.

In a third aspect the present invention provides a use of the epoxy resin produced with the method according to the present invention or the epoxy resin according to the present invention as a tackifier in adhesive compositions or as an adhesive.

In a fourth aspect the present invention provides an article comprising a volume housing the epoxy resin produced with the method of the present invention or the epoxy resin of the present invention.

In a fifth aspect the present invention provides an article comprising a first volume housing the modified tall oil pitch and a separate second volume housing the epoxidized vegetable oil.

It has been surprisingly found that biobased epoxy resin can be produced by a simple method comprising mixing tall oil pitch, modified tall oil pitch or a mixture thereof with at least one epoxidized vegetable oil; and curing the obtained mixture.

It was found that the epoxy resin can be produced substantially with only one hardener, i.e. tall oil based hardener, such as tall oil pitch, modified tall oil pitch or a mixture thereof. Preferably the epoxy resin is substantially free, preferably free from other hardeners than the tall oil based hardener.

It was additionally surprisingly found that the epoxy resin can be used as a tackifier in adhesive compositions or as an adhesive.

It was also found that the properties of the epoxy resin can be adjusted in a simple way. The properties of the epoxy resin can be affected by adjusting ratio of the components, i.e. reagents in the method for producing the epoxy resin. The properties of the epoxy resin can also be adjusted by choice of the epoxidized vegetable oil and by adjusting the modification of the modified tall oil pitch. Additionally, the properties of the epoxy resin can be affected by adjusting degree of cross-linking of the epoxy resin.

Depending on said adjustment(s) the produced epoxy resin can be viscous or elastic. Without bounding to any theory, it is believed that the viscous epoxy resin can most suitably be used as a tackifier in adhesive compositions and the elastic epoxy resin can most suitably be used as an adhesive.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows comparison of viscosity and softening points of epoxy resins according to the present invention.

DETAILED DESCRIPTION

In a first aspect the present invention provides a method for producing an epoxy resin comprising mixing tall oil pitch, modified tall oil pitch or a mixture thereof and at least one epoxidized vegetable oil for producing a mixture comprising the tall oil pitch, modified tall oil pitch or a mixture thereof and the at least one epoxidized vegetable oil; and curing the mixture, preferably curing thermally the mixture.

In one embodiment the tall oil pitch is mixed with the epoxidized vegetable oil.

In one embodiment the modified tall oil pitch is mixed with the epoxidized vegetable oil.

In one embodiment a mixture of tall oil pitch and modified tall oil pitch is mixed with the epoxidized vegetable oil.

The mixing can be any suitable method known in the art that mixes tall oil pitch, modified tall oil pitch or a mixture thereof and epoxidized vegetable oil.

In one embodiment the tall oil pitch, the modified tall oil pitch or a mixture thereof and the at least one epoxidized vegetable oil are mixed under an inert atmosphere, preferably under nitrogen gas. In one embodiment the tall oil pitch, modified tall oil pitch or a mixture thereof and the at least one epoxidized vegetable oil are mixed in a liquid medium, preferably in melted tall oil pitch, melted modified tall oil pitch or a mixture thereof.

The curing can be any suitable method known in the art. During the curing the epoxidized vegetable oil cross-links with the tall oil pitch, modified tall oil pitch or a mixture thereof. In one embodiment the mixture is cured thermally, i.e. by applying heat to the mixture.

Tall oil pitch can be produced from crude tall oil with any suitable method known in the art. Tall oil pitch is also commercially available. The tall oil pitch can be any suitable tall oil pitch.

Modified tall oil pitch can be produced from tall oil pitch with any suitable method known in the art. Modified tall oil pitch are also commercially available. The modified tall oil pitch can be any suitable modified tall oil pitch.

In one embodiment the tall oil pitch is modified with at least one alpha-unsaturated carboxylic acid, at least one anhydride of alpha-unsaturated carboxylic acid, at least one anhydride of unsaturated dicarboxylic acid or a combination thereof.

In one embodiment the modified tall oil pitch is modified with acrylic acid, acrylic anhydride, maleic acid, maleic anhydride, fumaric acid, methacrylic acid, itaconic acid, itaconic anhydride, citraconic acid or a combination thereof.

The vegetable oil can be any suitable vegetable oil. Vegetable oils are commercially available.

In one embodiment the vegetable oil is unsaturated vegetable oil, preferably polyunsaturated vegetable oil.

In one embodiment the vegetable oil contains at least three double bonds in its molecule.

In one embodiment the vegetable oil comprises soybean oil, grape seed oil, grapefruit seed oil, linseed oil, canola oil, cottonseed oil, corn oil, olive oil, palm oil, peanut oil, sunflower oil, coconut oil, rapeseed oil, safflower oil, sesame oil, hazelnut oil, almond oil, cashew oil, hazelnut oil, pecan oil, pine nut oil, pistachio oil, walnut oil, pumpkin seed oil, lemon oil, orange oil, acai oil, watermelon seed oil or a mixture thereof. Epoxidized vegetable oils can be produced with any suitable method known in the art. Epoxidized vegetable oils are also commercially available. The epoxidized vegetable oil can be any suitable epoxidized vegetable oil.

In one embodiment the epoxidized vegetable oil comprises epoxidized vegetable oils containing at least two epoxy groups in its molecule.

In one embodiment the epoxidized vegetable oil comprises epoxidized soybean oil, epoxidized grape seed oil, epoxidized grapefruit seed oil, epoxidized linseed oil, epoxidized canola oil, epoxidized cottonseed oil, epoxidized corn oil, epoxidized olive oil, epoxidized palm oil, epoxidized peanut oil, epoxidized sunflower oil, epoxidized coconut oil, epoxidized rapeseed oil, epoxidized safflower oil, epoxidized sesame oil, epoxidized hazelnut oil, epoxidized almond oil, epoxidized cashew oil, epoxidized hazelnut oil, epoxidized pecan oil, epoxidized pine nut oil, epoxidized pistachio oil, epoxidized walnut oil, epoxidized pumpkin seed oil, epoxidized lemon oil, orange oil, epoxidized acai oil, epoxidized watermelon seed oil or a mixture there thereof.

Properties of the epoxy resin can be affected by adjusting ratio of the components, i.e. reagents in the method for producing the epoxy resin. The properties of the epoxy resin can also be adjusted by choice of the epoxidized vegetable oil and by adjusting the modification of the modified tall oil pitch. Additionally, the properties of the epoxy resin can be affected by adjusting degree of cross-linking of the epoxy resin.

The more modified tall oil pitch is used in relation of epoxidized vegetable oil, the higher is the softening point and viscosity of the epoxy resin.

An epoxy resin having low density of crosslinking has lower viscosity, lower softening point and higher solubility. Epoxy resin having high density of crosslinking has higher viscosity, higher softening point and lower solubility.

Without bounding to any theory, it is believed that an epoxy resin having lower viscosity, lower softening point, lower density of crosslinking and/or higher solubility (i.e. viscous epoxy resin) is suitable as a tackifier in an adhesive composition; and epoxy resin having higher viscosity, higher softening point, higher density of crosslinking and/or lower solubility (i.e. elastic epoxy resin) is suitable as an adhesive. In one embodiment weight amount of the modified tall oil pitch is in excess to weight amount of the at least one epoxidized vegetable oil.

In one embodiment ratio of wt-% amount of the modified tall oil pitch to wt-% amount of the at least one epoxidized vegetable oil is at least 1.1 , such as from 1.1 to 50, preferably at least 2, such as from 2 to 50, more preferably at least 4, such as from 4 to 50, even more preferably from 5 to 50, even further preferably from 10 to 50, such as from 10 to 45.

In one embodiment the ratio of wt-% amount of the modified tall oil pitch to wt-% amount of the at least one epoxidized vegetable oil is from 45 to 50.

In one embodiment the modified tall oil pitch is mixed with the at least one epoxidized vegetable oil for 30 min - 600 min, preferably 30 min - 480 min for producing the mixture comprising the tall oil pitch and the at least one epoxidized vegetable oil.

In one embodiment the modified tall oil pitch is mixed with the at least one epoxidized vegetable oil for 480 min - 600 min for producing the mixture comprising the tall oil pitch and the at least one epoxidized vegetable oil.

In one embodiment the modified tall oil pitch is mixed with the at least one epoxidized vegetable oil at 100 °C - 200 °C, preferably 120 °C - 180°C or 30 min - 600 min for producing the mixture comprising the tall oil pitch and the at least one epoxidized vegetable oil.

In one embodiment the modified tall oil pitch is mixed with the at least one epoxidized vegetable oil at 100 °C - 120 °C for producing the mixture comprising the tall oil pitch and the at least one epoxidized vegetable oil.

In a second aspect the present invention provides an epoxy resin, wherein the epoxy resin comprises essentially at least one epoxidized vegetable oil cross-linked essentially with modified tall oil pitch.

In one embodiment the epoxy resin comprises at least one epoxidized vegetable oil crosslinked with modified tall oil pitch.

In one embodiment the epoxy resin is at least one epoxidized vegetable oil cross-linked with modified tall oil pitch. In one embodiment the epoxy resin is formed by a method comprising mixing modified tall oil pitch and at least one epoxidized vegetable oil; and curing the obtained mixture, preferably curing thermally the obtained mixture.

In one embodiment the tall oil pitch is modified with at least one alpha-unsaturated carboxylic acid at least one anhydride of alpha-unsaturated carboxylic acid, at least one anhydride of unsaturated dicarboxylic acid or a combination thereof.

In one embodiment the tall oil pitch is modified with acrylic acid, acrylic anhydride, maleic acid, maleic anhydride, fumaric acid, methacrylic acid, itaconic acid, itaconic anhydride, citraconic acid or a combination thereof.

The vegetable oil can be any suitable vegetable oil. Vegetable oils are commercially available.

In one embodiment the vegetable oil is unsaturated vegetable oil, preferably polyunsaturated vegetable oil.

In one embodiment the vegetable oil contains at least three double bonds in its molecule.

In one embodiment the vegetable oil comprises soybean oil, grape seed oil, grapefruit seed oil, linseed oil, canola oil, cottonseed oil, corn oil, olive oil, palm oil, peanut oil, sunflower oil, coconut oil, rapeseed oil, epoxidized safflower oil, sesame oil, hazelnut oil, almond oil, cashew oil, hazelnut oil, pecan oil, pine nut oil, pistachio oil, walnut oil, pumpkin seed oil, lemon oil, orange oil, acai oil, watermelon seed oil or a mixture thereof.

Epoxidized vegetable oils can be produced with any suitable method known in the art. Epoxidized vegetable oils are also commercially available. The epoxidized vegetable oil can be any suitable epoxidized vegetable oil.

In one embodiment the epoxidized vegetable oil comprises epoxidized vegetable oils containing at least two epoxy groups in its molecule.

In one embodiment the epoxidized vegetable oil comprises epoxidized soybean oil, epoxidized grape seed oil, epoxidized grapefruit seed oil, epoxidized linseed oil, epoxidized canola oil, epoxidized cottonseed oil, epoxidized corn oil, epoxidized olive oil, epoxidized palm oil, epoxidized peanut oil, epoxidized sunflower oil, epoxidized coconut oil, epoxidized rapeseed oil, epoxidized safflower oil, epoxidized sesame oil, epoxidized hazelnut oil, epoxidized almond oil, epoxidized cashew oil, epoxidized hazelnut oil, epoxidized pecan oil, epoxidized pine nut oil, epoxidized pistachio oil, epoxidized walnut oil, epoxidized pumpkin seed oil, epoxidized lemon oil, orange oil, epoxidized acai oil, epoxidized watermelon seed oil or a mixture there thereof.

In one embodiment ratio of wt-% amount of the modified tall oil pitch to wt-% amount of the at least one epoxidized vegetable oil is from 45 to 50.

In one embodiment the epoxy resin is produced with the method of the present invention.

In a third aspect the present invention provides a use of the epoxy resin produced with the method according to the present invention or the epoxy resin according to the present invention as a tackifier in adhesive compositions or as an adhesive.

In a fourth aspect the present invention provides an article comprising a volume housing the epoxy resin produced with the method according to the present invention or the epoxy resin according to the present invention.

In one embodiment the article comprises means configured to push out the epoxy resin from the volume.

In a fifth aspect the present invention provides an article comprising a first volume housing the modified tall oil pitch defined in the foregoing and a separate second volume housing the epoxidized vegetable oil defined in the foregoing.

In one embodiment ratio of wt-% amount of the modified tall oil pitch to wt-% amount of the at least one epoxidized vegetable oil is at least 1.1 , such as from 1.1 to 50, preferably at least 2, such as from 2 to 50, more preferably at least 4, such as from 4 to 50, even more preferably from 5 to 50, even further preferably from 10 to 50, such as from 10 to 45.

In one embodiment the ratio of wt-% amount of the modified tall oil pitch to wt-% amount of the at least one epoxidized vegetable oil is from 45 to 50.

In one embodiment the article comprises means configured to push out, preferably push out simultaneously the modified tall oil pitch from the first volume and the epoxidized vegetable oil from the second volume. EXAMPLES

Example 1 - according to the present invention - Method for producing modified tall oil pitch

Tall oil pitch and calculated amount of maleic anhydride were added to a round bottom 2I reaction flask (magnetic stirrer, egg-shaped bar, nitrogen inlet, thermal probe). The resulted mixture was stirred for 1 h at 185°C and 2h at 195°C under N2. Table 1 shows reagents used in the method and the results.

Table 1. Reagents used in the method and the results.

** MMA = maleic anhydride

*** an average of 2 parallel HPLC analysis

Example 2 - according to the present invention - Method for producing an epoxy resin

Modified tall oil pitch produced according to example 1 was transferred to a 2I wide mouth glass reactor (mechanical agitator, thermal probe, nitrogen inlet) and calculated amount of epoxidized soybean oil (ESO, M= 975.41 g/mol, theoretical content of oxirane groups per molecule is 6 or epoxide number of ESO ~ 162.6g) was added. The resulting mixture was stirred under nitrogen at 160°C for 2,5h and for 1 h at 170°C. Sample 5 formed gel after 2h at 160°C, a curing process was stopped. Table 2 shows the reagents used for producing the epoxy resins (samples 1-5). Table 3 shows softening point (SP), ash content and viscosity of the epoxy resins (samples 1-5). Figure 1 shows comparison of viscosity and softening points of the epoxy resins, samples 1-5.

Table 2. The reagents used for producing the epoxy resins. *The percentage value in the parenthesis after the sample number means amount of maleic anhydride in the tall oil pitch (TOP), i.e. modified TOP.

Table 3. Properties of the epoxy resins, samples 1-5.

**The percentage value in the parenthesis after the sample number means amount of maleic anhydride in the tall oil pitch (TOP), i.e. modified TOP before reacting with ESO. ***Softening point measurements were done by means of Ring&Ball system.

****Shear rheological measurements were done by means of Cone&Plate system with spindle CP25-2 and starting shear rate 500 s’ ¹ . Various embodiments have been presented. It should be appreciated that in this document, words comprise, include, and contain are each used as open-ended expressions with no intended exclusivity.

The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention.

Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.