KR101831737B1 - Rigid polyurethane foam and preparation method thereof - Google Patents

Abstract

A hard polyurethane foam which is a polymerization product of a composition comprising a polyol and an isocyanate, and a process for producing the same.

Description

TECHNICAL FIELD The present invention relates to a rigid polyurethane foam and a preparation method thereof,

Rigid polyurethane foam and a process for producing the same.

As fossil resources such as petroleum and coal as industrial raw materials are expected to be depleted, interest in biomass that can be used permanently is increasing. Among biomass, woody biomass is highly utilized because there is no other competitive use such as food resources. Woody biomass consists of carbohydrates such as cellulose and lignin. Lignin is a natural phenolic polymer accounting for 15 to 20% of woody biomass.

On the other hand, rigid polyurethane foam has excellent heat insulating properties and flame retardancy. Therefore, it is widely used in refrigerators, freezers, insulation materials for general buildings, and insulation panels. Rigid polyurethane foams can generally be prepared by reacting a polyol with an isocyanate under a catalyst.

Recently, attempts have been made to use lignin derived from biomass in the production of rigid polyurethane foam. For example, the lignin sulfonate obtained in the sulfite pulping process, the alkali lignin obtained in the soda pulping process, and the kraft lignin obtained in the kraft paper production process can be used.

However, the lignins are difficult to dissolve in the polyol, or cause excessive crosslinking to lower the physical properties of the rigid polyurethane foam. In order to solve this problem, it has been used in the manufacture of polyurethanes by lowering the hydroxyl value of lignin through chemical modification such as acetylation or esterification. Thus, it is possible to replace rigid poly Urethane foam is required.

The present invention provides a novel rigid polyurethane foam and a process for producing the same.

According to one aspect,

There is provided an article comprising a rigid polyurethane foam and a rigid polyurethane foam which is a polymerization product of a composition comprising a polyol and an isocyanate.

According to another aspect,

And reacting the polyol and the isocyanate in the presence of a foam stabilizer, a catalyst and a foaming agent, to prepare a rigid polyurethane foam.

Rigid polyurethane foam having excellent physical properties can be produced without additional chemical modification by using lignin as a material derived from biomass.

Hereinafter, rigid polyurethane foam according to an exemplary embodiment and a method for producing the same will be described in more detail.

A rigid polyurethane foam according to one embodiment is a polymerization product obtained by reacting a composition comprising lignin strongly acidified with polyol and isocyanate. The rigid polyurethane foam can be produced by using ordinary lignin to produce rigid polyurethane foam of excellent physical properties without additional chemical modification that was required in producing rigid polyurethane foam. In particular, the hard polyurethane foam using the lignin strong acid can shorten the manufacturing process and improve the density, the compressive strength, the flame retardancy, and the like, as compared with the rigid polyurethane foam produced by using other conventional lignin .

The lignin strong acid used in the rigid polyurethane foam means lignin separated from the hydrolyzate obtained by hydrolyzing woody biomass into strong acid. For example, the lignin strong acid can be prepared in the following manner. First, woody biomass is mixed with strong acid. Subsequently, an excess amount of water is added to the mixture to dilute, and the residue is filtered. The residue is then washed with water to obtain a residue which is neutral in pH. The neutral residue is dried to give a lignin-dried powder.

For example, the pH of the lignin acid obtained in the form of a dry powder may be 4 to 7. By using lignin strong acid having a pH in the above range, a rigid polyurethane foam having improved physical properties can be obtained. If the pH of the strong acid lignin is less than 3, there may be corrosion problems when the prepared rigid polyurethane foam is used for reinforcing steel protection.

The strong acid used in the production of the lignin strongly acid may be hydrochloric acid, but it is not limited thereto and other acid such as sulfuric acid, nitric acid, phosphoric acid and Lewis acid can be used in the technical field to lower the physical properties of the hard polyurethane foam If not, it is all possible.

The content of lignin acid used in the preparation of the rigid polyurethane foam may be 1 wt% to 40 wt% based on the total weight of the polyol and the lignan lignin mixture to be added. Specifically, the content of the lignin strongly acidic in the mixture of the polyol and the lignan lignin may be 10 wt% to 35 wt% of the total weight of the mixture of the polyol and the lignan lignin. More specifically, the content of the lignin strongly acidic in the mixture of the polyol and the lignan lignin may be 10% to 30% by weight of the total weight of the mixture of the polyol and the lignan strong acid. More particularly, the content of lignin-rich acid in the mixture of polyol and lignan lignin may be 10% to 20% by weight of the total weight of the mixture of polyol and lignan lignin. If the content of the lignin strong acid exceeds 40% by weight, the viscosity of the mixture of the polyol and the strong lignin is excessively increased and hardened, so that it may be difficult to produce the rigid polyurethane foam.

The hydroxyl value of the strong acid lignin used in the rigid polyurethane foam may be included in the hydroxyl value range of the polyol. That is, the lignin strong acid may have a hydroxyl value in the same range as that of the polyol used in the production of the rigid polyurethane foam. Since the lignin strong acid has a hydroxyl value in the same range as that of the polyol, it is possible to prevent deterioration of the physical properties of the rigid polyurethane foam due to the use of lignin strongly acidic.

The hydroxyl value of the strong lignin used in the rigid polyurethane foam may be 500 mg KOH / g or less. Specifically, the hydroxyl value of the lignin strong acid used in the rigid polyurethane foam may be 300 mg KOH / g to 500 mg KOH / g. If the hydroxyl value of the lignin strong acid is less than 300 mg KOH / g, the viscosity of the mixture of the lignin strong acid and the polyol may be excessively increased or the mechanical strength of the rigid polyurethane foam may be lowered. When the hydroxyl value of the lignin strong acid is more than 500 mg KOH / g, the unreacted alcohol has a high molecular weight distribution, so that the brittleness of the polyurethane is weakened and the amount of isocyanate reacting with the mixture of lignin with polyol increases, The molar ratio of tate may exceed the appropriate range.

For example, the density of the rigid polyurethane foam produced using the lignin strongly acidic, polyol and isocyanate may be greater than 25.0 kg / m < ³ >. For example, the density of the rigid polyurethane foam may be 25.0 kg / m ³ to 70 kg / m ³ . If the density of the rigid polyurethane foam is less than 25.0 kg / m ^3, flame retardancy or mechanical strength may be lowered. If the density of the rigid polyurethane foam is 70 kg / m < ³ > or more, the cost may be excessively increased.

The compressive strength of the rigid polyurethane foam produced using the composition comprising the lignin strong acid, polyol and isocyanate may be greater than or equal to 0.005 kgf / mm ² . Preferably 0.005 kgf / mm ² to 0.05 kgf / mm ² . If the compressive strength of the hard polyurethane foam is less than 0.005 kgf / mm ^2, flame retardancy or mechanical strength may be lowered. If the compressive strength of the rigid polyurethane foam exceeds 0.05 kgf / mm ^{2, the} cost may be excessively increased.

An article comprising the rigid polyurethane foam according to another embodiment is provided. The article may be a polyurethane foamed molded article. The molded article can be used for various parts such as automobile parts, machine parts, industrial parts, electric wires, cables, rolls, hoses, tubes, belts, films, sheets, laminates, coatings, adhesives, Nursing articles, housing articles, medical care, construction materials, civil engineering, waterproofing materials, packaging materials, insulating materials, insulation materials, and slush powders. In addition, a suitable face material may be provided on one or both sides of the polyurethane foam. The face plate can be, for example, paper, wood, gypsum board, resin, aluminum foil, steel plate, and the like.

According to another embodiment, a method of producing a rigid polyurethane foam comprises reacting strongly acidic lignin, a polyol and an isocyanate in the presence of a foam stabilizer, a catalyst and a foaming agent. By the above production method, rigid polyurethane foam having physical properties such as improved density and compressive strength can be produced.

Preparing a pre-mix comprising lignin stronginic acid, a polyol, a foam stabilizer, a catalyst, and a foaming agent, wherein the step of reacting the lignin strong acid, the polyol and the isocyanate in the above- And reacting the premix with isocyanate.

The preparation method may further include preparing a mixture by mixing the lignin strong acid and the polyol before preparing the premix.

In the above production process, the mixing of the polyol with the strong acid lignin can be carried out at a temperature of 50 ° C to 85 ° C for 0.5 to 2 hours. By mixing at the above-mentioned temperature, the viscosity of the polyol is decreased, so that the mixing of the polyol with the lignin strong acid can be facilitated. After the strong acid lignin and polyol are completely mixed, they can be cooled to below 45 ° C to inhibit the volatilization of other materials added.

In the above production method, the content of lignin strong acid is as described above.

The polyol used in the above production method may be, but is not necessarily limited to, a polyether polyol, a polyester polyol, a polyolefin polyol, a low molecular polyol, a flame retardant polyol, an acrylic polyol, Any that can be used in the production of the foam is possible.

For example, as the polyether polyol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and the like can be used. For example, as polyester polyol, adipate-based polyol, polycaprolactone polyol, aromatic polyester polyol, polycarbonate diol and the like can be used. Examples of the adipate-based polyol include ethylene glycol adipate, diethylene adipate glycol, butylene glycol adipate, trimethylolpropane / diethylene glycol adipate, and the like. For example, a polybutadiene polyol, a hydrogenated polybutadiene polyol, a hydrogenated isoprene polyol, or the like can be used as the polyolefin-based polyol. As low-molecular polyols, 1,4-butanediol, 1,6-hexanediol, 1,3-propanediol, 2-methyl-propanediol and the like can be used. As the flame-retardant polyol, a phosphorus-containing polyol, a halogen-containing polyol, a phenol-based polyol and the like can be used. As the plant-derived polyol, polyols derived from castor oil, soybean oil, palm oil and the like can be used. The polyol may be used alone or in a mixture of two or more.

The molecular weight of the polyol may range from 400 to 8000. Specifically, the molecular weight of the polyol may be 450 to 5000. More specifically, the molecular weight of the polyol may be 500-3000. If the molecular weight of the polyol is less than 400, the flexibility and heat resistance of the polyurethane may be deteriorated. When the molecular weight of the polyol is more than 8000, compatibility with other polyols or isocyanates is lowered, and uniform polyurethane can not be obtained.

The hydroxyl value of the polyol may be 20 to 500 mgKOH / g, and the number of functional groups per molecule of the polyol may be 2.0 to 8.0.

The isocyanate index of the isocyanate may be from 50 to 500 in the above production process.

Isocyanate Index = 100 x (actual NCO content used) / (theoretical NCO content required)

Specifically, it may be 50 to 300. [ And more preferably from 50 to 200. [ If the index exceeds 500, the hardness of the rigid polyurethane foam increases and the adhesive strength may be lowered. If the index is less than 50, the flame retardancy and compressive strength of the rigid polyurethane may be lowered.

The isocyanate used in the above production method is not particularly limited as long as it is a polyisocyanate having two or more isocyanate groups in one molecule. For example, the polyisocyanate may be an aliphatic isocyanate, an alicyclic isocyanate, an aromatic isocyanate, or a modified product thereof. As the aliphatic isocyanate, for example, hexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate can be used. As the alicyclic isocyanate, for example, isophorone diisocyanate can be used. As aromatic isocyanates, for example, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, triphenylmethane triisocyanate, tris (isocyanate phenyl) thiophosphate and the like can be used have. As the isocyanate-modified product, for example, urethane prepolymer, hexamethylene diisocyanate buret, hexamethylene diisocyanate trimer, isophorone diisocyanate trimmer and the like can be used. Plant-derived isocyanates such as castor oil can also be used. The isocyanate may be used alone or in a mixture of two or more.

The catalyst used in the process may be a tertiary amine as an urethane catalyst. As the trimerization reaction accelerating catalyst, a metal salt and / or a quaternary ammonium salt may be used. When an isocyanate is used, an urethanation catalyst and a trimerization promoting catalyst may be used in combination. For example, a tertiary amine and a metal salt and / or a quaternary ammonium salt may be used in combination.

As tertiary amines there may be mentioned N, N, N ', N'-tetramethylethylenediamine, N, N, N' N, N ', N' '- N'-pentamethyldiethylenetriamine, N, N, N' Tri (N, N-dimethylaminopropyl) hexahydro-s-triazine, 1,8-diazabicyclo [ 5.4.0] undecene-7, triethylenediamine, N, N, N ', N'-tetramethylhexamethylenediamine, N, N'-dimethylpiperazine, dimethylcyclohexylamine, N-methylmorpholine, N -Ethylmorpholine, bis (2-dimethylaminoethyl) ether, 1-methylimidazole, 1,2-dimethylimidazole, 1- Sol, N-methyl-N- (N, N-dimethylaminoethyl) ethanolamine, and the like. However, the present invention is not limited to these, and any of them can be used as an amine catalyst in the art.

As the metal salt, potassium salt, tin salt, lead salt and the like can be used. For example, potassium acetate, potassium 2-ethylhexanoate, dibutyltin dilaurate, tin octylate, lead octylate, and bismuth 2-ethylhexanoate may be used. However, the present invention is not limited to these, and any metal catalyst can be used in the art.

Examples of the quaternary ammonium salt include tetraalkylammonium halides such as tetramethylammonium chloride; Tetraalkylammonium hydroxides such as tetramethylammonium hydroxide; Tetraalkylammonium organic acid salts such as tetramethylammonium 2-ethylhexanoate, 2-hydroxypropyltrimethylammonium formate and 2-hydroxypropyltrimethylammonium 2-ethylhexanoate; A quaternary ammonium compound obtained by subjecting a quaternary ammonium carbonate obtained by the reaction of a tertiary amine such as N, N, N'N'-tetramethylethylenediamine and a carbonic acid diester to a reaction with 2-ethylhexane is used .

The amount of the catalyst to be used may be 0.1 to 5 parts by weight based on 100 parts by weight of the mixture of lignin-strong acid and polyol, but is not limited thereto and may be suitably adjusted within a range that can produce a rigid polyurethane foam having improved physical properties. Depending on the amount of the catalyst used, the reactivity of the mixture of lignin with polyol and isocyanate can be controlled. That is, the time from the start of mixing to the end of foaming by the naked eye can be controlled.

Examples of the foaming agent used in the production method include HCFC-based foaming agents such as HCFC-141b, HCFC-142b, HCFC-124 and HCFC-22; 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3-pentafluoro Tetrafluoroethyldifluoromethyl ether (HFE-236pc), 1,1,2,2-tetrafluoroethyl methyl ether (HFE-254pc), 1,1,2,2- , And 1,1,1,2,2,3,3-heptafluoropropyl methyl ether (HFE-347mcc); Hydrocarbon-based foaming agents such as butane, hexane, cyclohexane, n-pentane, iso-pentane and cyclopentane; water; Inert gas such as air, nitrogen, carbon dioxide gas, or the like. However, the present invention is not limited thereto, and any of them can be used as a blowing agent in the technical field. The addition state of the inert gas may be any of liquid state, supercritical state and subcritical state. When a blowing agent other than water is used, they may be used alone or in combination of two or more.

When water is used as the blowing agent, the content of water may be 0.5 to 10 parts by weight based on 100 parts by weight of the mixture of the lignin-strong acid and the polyol. Specifically, it may be 0.5 to 7 parts by weight. When the pentane (n-pentane, isopentane, and / or cyclopentane) is used as the foaming agent, the content of pentane (n-pentane, isopentane, and / or cyclopentane) 0.5 to 60 parts by weight. Specifically, it may be 0.5 to 50 parts by weight.

As the foaming agent (surfactant) used in the above-mentioned production method, for example, a silicon foaming agent, a fluorinated compound-based foaming agent and the like can be used. However, the present invention is not limited to these, and any of them can be used as the foam stabilizer in the technical field. Specifically, a silicone foam stabilizer can be used to form a good foam.

As the silicone foam former, a compound containing a block copolymer of dimethylpolysiloxane and polyether can be used. Examples thereof include L-6884, L-5440 and L-5420 manufactured by Momentive such as SZ-1671, SZ-1718, SH-193 and SZ-1642 manufactured by Toray-Dow Corning, , B8490, B8460, and the like can be used.

The content of the foaming agent may be 0.1 to 10 parts by weight based on 100 parts by weight of the mixture of the lignin-strong acid and the polyol. For example, the amount of the stabilizer may be 0.3 to 5 parts by weight based on 100 parts by weight of the mixture of lignin and polyol.

In the above production method, a flame retardant may be selectively used.

Examples of the flame retardant to be used include phosphate esters such as triethyl phosphate, tributyl phosphate, tris chloroethyl phosphate, tris chloropropyl phosphate (abbreviated as TCPP), triphenyl phosphate, tricresyl phosphate and polyphosphoric acid, Of phosphoric acid compounds, chlorinated paraffin, and the like.

The amount of the flame retardant to be used may be 10 to 60 parts by weight based on 100 parts by weight of the mixture of lignin and polyol so as to ensure both excellent mechanical properties and flame retardancy in the obtained rigid foam. For example, the content of the flame retardant may be 20 to 40 parts by weight based on 100 parts by weight of the mixture of the lignin-strong acid and the polyol.

In the above production method, other compounding agents may be additionally used.

In the above-mentioned production method, lignin strong acid, a polyol, an isocyanate, a catalyst, a foaming agent, a foam stabilizer and an optional compounding agent may be additionally used. A filler such as calcium carbonate and barium sulfate as a compounding agent; Antioxidants such as antioxidants and ultraviolet absorbers; A plasticizer, a colorant, an antifungal agent, a spreading agent, a dispersant, and a discoloration inhibitor.

The present invention will be described in more detail by way of the following examples and comparative examples. However, the examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

(Preparation of Rigid Polyurethane Foam)

Example  1: Pine Origin Strong acid lignin

(Preparation of lignin strongly acidic)

Pine trees were used as lignocellulosic biomass. 42% hydrochloric acid was mixed at a weight ratio of 1: 5 (w / v) to the raw material crushed to a diameter of 0.8 mm or less and agitated at 20 ° C for 5 hours, and then an excess amount of water was added to dilute the hydrochloric acid. Subsequently, the diluted solution was filtered using a stainless steel sieve (325-ASTM). The filtered residue was washed with water until pH of 4 or more was neutral, and then dried in an oven at 70 ° C to obtain hydrochloric acid-hydrolytic lignin. The sugar component contained in the lignin hydrochloride was less than 5% by weight, and the chlorine content was 1% by weight or less.

(Manufacture of premix)

10 g of the above prepared lignin lignin and 90 g of a commercial liquid polyol (Lupranol ^® 3422, polypropylene glycol, Mw = 600, BASF) were fed into the reactor. The above lignin strong acid and the common polyol were stirred at 85 rpm for 1 hour at 300 rpm to prepare a mixture of lignin-strong acid and polyol. The temperature of the mixture was cooled to 45 占 폚. 1.5 g of a silicone foam stabilizer (TEGOSTAB ^® B-8409, Evonik Industries), 2.0 g of an amine catalyst (Dabco ^® 33-LV, Air Products and Chemicals, Inc.) as a main catalyst, DBTDL, dibutyltin dilaurate, Sigma), and 28.5 g of n-pentane as a blowing agent was added to prepare a premix. The specific composition thereof is shown in Table 1 below.

(Preparation of Rigid Polyurethane Foam)

119 g of isocyanate (polymeric MDI, Suprasec 5005, NISCHEM) was added to the premix to prepare a rigid polyurethane foam. The addition amount of isocyanate was determined according to the addition amount of the hydroxyl group of the premix and the foaming agent so that the isocyanate index was 100.

The premix and isocyanate were rapidly charged into a polyethylene container at room temperature, stirred at 3,000 rpm for 3 seconds, and foamed in a 1 L container to prepare a rigid polyurethane foam.

Example  2 to 10

A rigid polyurethane foam was prepared in the same manner as in Example 1, except that the composition of the components used in the rigid polyurethane foam was changed. The specific composition is shown in Table 1 below.

Comparative Example  One

A rigid polyurethane foam was prepared in the same manner as in Example 1, except that 100 g of a commercial liquid polyol was used instead of the lignin strong acid.

Comparative Example  2

A rigid polyurethane foam was prepared in the same manner as in Example 1, except that the content of lignin acid was changed to 50 g.

Commercial polyol Lignin Foaming agent catalyst blowing agent Isocyanate Example 1 90 10 1.5 2.3 28.5 119 Example 2 90 10 1.5 2.3 47.0 119 Example 3 90 10 1.5 2.3 1.0 (water) 134 Example 4 80 20 1.5 2.3 28.5 115 Example 5 70 30 1.5 2.3 28.5 112 Example 6 70 30 1.5 2.3 47.0 112 Example 7 70 30 1.5 2.3 1.0 (water) 127 Example 8 60 40 1.5 2.3 28.5 108 Example 9 60 40 1.5 2.3 47.0 108 Example 10 60 40 1.5 2.3 1.0 (water) 124 Comparative Example 1 100 0 1.5 2.3 28.5 122 Comparative Example 2 50 50 1.5 2.3 28.5 105

In Table 1, the unit of each component is g. In Examples 3, 7 and 10, water was used instead of n-pentane as a foaming agent.

Evaluation example  1: Measurement of hydroxyl value

The hydroxyl groups of lignin strongly acid were measured according to ASTM D-4274-99. The hydroxyl value is defined as the weight of KOH (mgKOH / g) required to neutralize the acetic acid bound to the acetyl compound obtained from 1 g of polyol.

0.2 g of lignin strong acid and 10 ml of pyridine and 1.3 ml of acetic anhydride were added to a blank and reacted in a water bath at 98 ± 2 ° C for 2 hours and then cooled to room temperature. The reaction solution was transferred to a conical tube while adding distilled water (30 ml), and 45.5 ml of distilled water was added again. The supernatant was recovered. 40 ml of distilled water was added to the precipitate and centrifuged to recover the supernatant. And collected the recovered supernatant. To the supernatant was added 1 ml of 1% phenolphthalein drug, and the amount of NaOH added until it became a pale pink of the solution was measured while stirring with 0.5 N NaOH solution while stirring. From the added amount of NaOH, hydroxyl value was calculated using the following formula (2).

&Quot; (2) "

(MgKOH / g) = [(NaOH input amount of blank (ml) - NaOH input amount of lignin (ml)) × concentration of NaOH solution (N) × 56.1] / amount of lignin added (g)

The hydroxyl value of the lignin-derived lignin of pine of Example 1 was 350 mgKOH / g and the hydroxyl value of the acacia-derived lignin of Example 13 was 419 mgKOH / g. The hydroxyl value of the commercial polyol used in the production of the rigid polyurethane foam is in the range of 350-560 mgKOH / g, and the hydroxyl value of the lignin of the strong acid is within the hydroxyl value of the commercial polyol.

Evaluation example  2: Reactivity

The mixing start time of the premix and isocyanate was set to 0 seconds, and the time until the foaming starts to occur in the foaming stock solution composition was determined as a cream time. The time when the foaming stock solution composition started foaming and the rise of the hard foam was stopped Was defined as the gel time. The measurement results are shown in Table 2 below. The shorter the cream time and the gel time, the better the reactivity.

Evaluation example  3: Density (Cup free  Density) measurement

The core of the obtained rigid foam was cut into cubes having a length of 70 mm, a width of 70 mm and a thickness of 70 mm, and the density (unit: kg / m ³ ) was calculated from the weight and the volume.

Evaluation example  4: Compressive strength measurement

It was measured by the method according to JIS K-6400, and the value at the time when the thickness of the test piece was compressed by 25% was shown.

Reactivity
density
[kg / m ³ ]
Compressive strength
[kgf / mm ² ] Cream time
[second] Gel time
[second] Example 1 65 200 26.4 0.013 Example 5 60 190 25.8 0.011 Example 8 60 190 25.5 0.009 Comparative Example 1 65 200 27.6 0.013 Comparative Example 2 - - - -

As shown in Table 2, the rigid polyurethane foam of the Example exhibited similar physical properties to the rigid polyurethane foam not containing the lignin of Comparative Example 1, and the reactivity was improved.

In Comparative Example 2, the viscosity of the premix was increased and the rigid polyurethane foam was not properly formed.

Thus, it was confirmed that a rigid polyurethane foam can be prepared by replacing a part of the polyol without additional chemical modification to the lignin strong acid.

Claims (11)

Hydrolyzing the woody biomass into a strong acid;
Washing the hydrolyzate so that the pH of the hydrolyzate is 4 to 7, and then drying to prepare a dry powder of lignin strongly acidic at a pH of 4 to 7; And
Reacting the strongly acidic lignin powder, the polyol and the isocyanate at a pH of 4 to 7 in the presence of a foam stabilizer, a catalyst and a foaming agent,
Wherein the content of the lignin strongly acidic is 1 wt% to 40 wt% of the total weight of the mixture of the polyol and the lignan strong acid. The method according to claim 1,
The step of reacting the strong lignin, polyol and isocyanate,
Preparing a premix comprising a strong acid lignin, a polyol, a foam stabilizer, a catalyst and a foaming agent; And
And reacting the premix with isocyanate to produce a rigid polyurethane foam. 3. The method of claim 2,
Before preparing the premix
Further comprising the step of preparing a mixture by mixing the polyol with the strong acid lignin. The method of claim 3,
Wherein the mixing of the polyol with the strong acid lignin is carried out at a temperature of from 50 캜 to 85 캜 for 0.5 to 2 hours. A hard polyurethane foam produced by the process according to any one of claims 1 to 4. A hard polyurethane foam which is a polymerization product of a composition comprising a strong acid lignin powder having a pH of 4 to 7, a polyol and an isocyanate,
The lignin strong acid is lignin separated from the hydrolyzate obtained by hydrolyzing woody biomass into strong acid,
Wherein the content of the lignin strongly acidic is 1 wt% to 40 wt% of the total weight of the mixture of the polyol and the lignan strong acid. The rigid polyurethane foam according to claim 6, wherein the strong acid is selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and Lewis acid. The rigid polyurethane foam according to claim 6, wherein the content of the lignin strongly acidic is 10% by weight to 30% by weight of the total weight of the mixture of the polyol and the strong lignin. 7. The rigid polyurethane foam according to claim 6, wherein the hydroxyl value of the lignin strongly acid is included in the hydroxyl value range of the polyol. The rigid polyurethane foam according to claim 6, wherein the hydroxyl value of the lignin strongly acid is 300 mg KOH / g to 500 mg KOH / g. An article comprising a rigid polyurethane foam according to any one of claims 6 to 10.