KR20230165034A - Prepolymer for preparing polyurethane foam, polyurethane foam and preparing method thereof - Google Patents

Abstract

A prepolymer for preparing a polyurethane foam according to an embodiment of the present invention is a prepolymer included in a composition for preparing a polyurethane foam, wherein the prepolymer has a linear long-chain form formed by reacting a short-chain first polyol with a first isocyanate, and the composition includes a second polyol and a second isocyanate. According to an embodiment of the present invention, a prepolymer capable of preparing a polyurethane foam having a high nucleation rate and a small pore size and a method for preparing the same are provided.

Description

Prepolymer for manufacturing polyurethane foam, polyurethane foam, and method for manufacturing the same {PREPOLYMER FOR PREPARING POLYURETHANE FOAM, POLYURETHANE FOAM AND PREPARING METHOD THEREOF}

The present invention relates to a prepolymer for producing polyurethane foam, a method for producing the same, and polyurethane foam.

Polyurethane foam is known as a material with excellent insulation properties, and is mainly used as an insulation material in refrigerators, freezer containers, and low-temperature warehouses that require high insulation properties. In particular, in the case of polyurethane foam insulation applied to storage tanks or LNG fuel tanks of LNG carriers, the higher the thermal conductivity of the insulation material, the higher the BOR (Boil-off Rate) due to LNG vaporization, resulting in large economic losses. Therefore, in order to reduce the boil-off rate (BOR) and maximize the remaining amount of LNG, an insulating material with superior insulating performance by further reducing thermal conductivity is required.

Since most heat transfer of polyurethane foam occurs through gas heat conduction, suppressing gas heat transfer is required to improve insulation performance. In this regard, polyurethane foam is known to have improved insulation performance as the pore size decreases.

In addition, when the pore size is reduced, the sound absorption performance of the polyurethane foam is also excellent, and the bending moment of the pore wall can be reduced, thereby improving the mechanical properties such as shock absorption and strength of the polyurethane foam.

Accordingly, in order to manufacture polyurethane foam with excellent thermal insulation performance and mechanical properties, there is a need for the development of polyurethane foam with a smaller pore size.

Republic of Korea Patent Publication No. 10-2009-0114962

One object of the present invention is to provide a prepolymer for producing polyurethane foam having improved thermal insulation performance, durability, etc., and a method for producing the same.

One object of the present invention is to provide polyurethane foam with superior insulation properties, durability, etc.

The prepolymer for producing polyurethane foam according to an embodiment of the present invention is a prepolymer included in a composition for producing polyurethane foam, and the prepolymer is a short-chain first polyol mixed with a first isocyanate. It is in a linear long-chain form formed by reacting with , and the composition includes a second polyol and a second isocyanate.

The prepolymer for producing polyurethane foam may have a different number average molecular weight depending on the composition of the composition for producing polyurethane foam.

The number average molecular weight of the prepolymer may be 10,000 to 150,000.

The prepolymer may be formed by reacting the first polyol and the first isocyanate at a molar ratio of 1:1 to 1.5.

The method for producing a pre-polymer for producing polyurethane foam according to an embodiment of the present invention is a method for producing a pre-polymer included in a composition for producing polyurethane foam, and includes first isocyanate and short-chain reacting the first polyol to form a linear long-chain prepolymer, wherein the composition includes a second isocyanate; and a second polyol.

In the method of producing the prepolymer for producing polyurethane foam, in the step of forming the prepolymer, the molecular weight of the prepolymer can be adjusted according to the composition of the composition for producing polyurethane foam.

Forming the prepolymer includes adding a catalyst to the first polyol and then stirring to remove moisture; Adding an anhydrous compound to the first polyol from which moisture has been removed in an inert gas atmosphere; And it may include adding the first isocyanate and reacting it with the first polyol.

The method for producing polyurethane foam according to an embodiment of the present invention can produce polyurethane foam using a composition for producing polyurethane foam containing the prepolymer.

The polyurethane foam according to one embodiment of the present invention is a polyurethane foam manufactured from a composition for producing polyurethane foam containing the above prepolymer, and has an apparent nucleation density (N _eff ) of 20,000 to 50,000/ according to Equation 1 below. It is mg.

[Equation 1]

In Equation 1, V _f corresponds to the reciprocal of the density (ρ _f ) of the polyurethane foam, and V _p is the average volume of pores of the polyurethane foam according to Equation 2 below.

[Equation 2]

In Equation 2 above, D is the pore diameter of the polyurethane foam.

The pore diameter (D) of the polyurethane foam may be 50 to 150 um.

According to one embodiment of the present invention, a prepolymer capable of producing polyurethane foam having a high nucleation rate and small pore size is provided.

According to one embodiment of the present invention, a prepolymer for manufacturing polyurethane foam is provided that can be directly applied to the existing polyurethane manufacturing process and thus ensures economic efficiency.

According to one embodiment of the present invention, a prepolymer for producing polyurethane foam that can be added under optimal conditions by appropriately adjusting the chain length and elongation viscosity depending on the composition of the polyurethane is provided.

According to one embodiment of the present invention, a prepolymer for producing polyurethane foam that has excellent compatibility with a composition for producing polyurethane foam and can control the pore size of polyurethane foam without problems such as dispersion is provided.

1 is a conceptual diagram showing a method for producing a prepolymer for producing polyurethane foam according to an embodiment of the present invention, conceptually showing a method for producing a linear long chain prepolymer by synthesizing a first polyol and a first isocyanate. This is the drawing shown.
Figure 2 is a view showing the results of observing polyurethane foam according to an example and a comparative example of the present invention using a scanning electron microscope (SEM).
Figure 3 is a diagram showing the effective nucleation density (N _eff ) of polyurethane foam according to an example and comparative example of the present invention.
Figure 4 is a diagram showing the pore size of polyurethane foam according to an example and comparative example of the present invention.
Figure 5 is a diagram showing the density of polyurethane foam according to an example and a comparative example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

As previously described, in order to manufacture polyurethane foam with better insulation performance, durability, etc., it is required to reduce the pore size of polyurethane foam. This means that the smaller the pore size, the more pores can be made into the areas between the pores, increasing the gas fraction of the polyurethane foam. The more pores serve as a barrier to prevent the diffusion of the foaming agent inside the polyurethane foam. This is believed to be because replacement with external air due to diffusion of the foaming agent can be delayed.

In this regard, one of the reasons why pores become larger when manufacturing polyurethane foam through foaming is suggested to be continuous growth of pores due to insufficient elongation viscosity and pore fusion due to destruction of pore walls.

Specifically, pores inside polyurethane foam are formed by nucleation. When individual pores formed at different locations meet each other as they expand, biaxial extensional flow occurs due to the difference in Laplace pressure between pores, and this phenomenon is called the foam drainage phenomenon. Also called Film Drainage. The degree of resistance to this elongation flow is called 'elongation viscosity', and the greater the elongation viscosity, the greater the force to resist elongation flow, which can inhibit the growth and fusion of pores. On the other hand, even if the elongation viscosity is sufficient, if the nucleation rate is not sufficient, there is a limit to controlling the growth of pores because foam drainage does not occur.

In addition, methods such as adding composites, blending, and crystallization have previously been used to control the pore size of polyurethane foam. However, composites and blending have poor compatibility with existing materials. There are limitations to its application due to dispersion problems, and in the case of crystallization, there are limitations due to the low crystallinity of polyurethane.

Accordingly, the inventors of the present invention confirmed that when adding a linear long-chain prepolymer to a composition for producing polyurethane foam, polyurethane foam with a high nucleation rate and small pore size can be produced, and the specific details thereof Implementations are described below with reference to FIGS. 1 to 5.

1 is a conceptual diagram showing a method for producing a prepolymer for producing polyurethane foam according to an embodiment of the present invention, conceptually showing a method for producing a linear long chain prepolymer by synthesizing a first polyol and a first isocyanate. This is the drawing shown.

Figure 2 is a view showing the results of observing polyurethane foam according to an example and a comparative example of the present invention using a scanning electron microscope (SEM).

Figure 3 is a diagram showing the effective nucleation density (N _eff ) of polyurethane foam according to an example and comparative example of the present invention.

Figure 4 is a diagram showing the pore size of polyurethane foam according to an example and comparative example of the present invention.

Figure 5 is a diagram showing the density of polyurethane foam according to an example and a comparative example of the present invention.

Prepolymer for manufacturing polyurethane foam

prepolymer

The prepolymer for producing polyurethane foam according to an embodiment of the present invention is a prepolymer included in a composition for producing polyurethane foam, and the prepolymer combines a short-chain first polyol with a first isocyanate. It is in a linear long-chain form formed by reaction, and the composition includes a second polyol and a second isocyanate.

A method of synthesizing a linear long-chain prepolymer according to the reaction of the first polyol and the first isocyanate is conceptually shown in FIG. 1. As shown in Figure 1, a linear long chain prepolymer can be produced by reacting a first polyol, a short-chain single molecule, with a first isocyanate to extend the chain connected by a urethane bond. there is.

The first polyol may be a single-molecule linear polyol in a short-chain form in which repeating units are combined into one chain. The first polyol may include polytetramethylene ether glycol (PTMEG), polypropylene glycol (PPG), and polyethylene glycol (PEG), and is preferably polyethylene glycol (PEG).

The number average molecular weight (M _n- ) of the first polyol may be 100 to 2000. Specifically, the number average molecular weight (M _n ) of the polyol may be 200 to 1000, or 300 to 500.

The hydroxyl value (OH value) of the first polyol may be 200 to 400. Specifically, the hydroxyl value of the second polyol may be 265 to 295.

The first polyol may react with the first isocyanate to form a urethane bond (-NHCOO-). The first isocyanate may be hexamethylene diisocyanate (HDI), polymethylene diphenyl diisocyanate (poly-MDI), toluene diisocyanate (TDI), etc., and preferably hexamethylene diisocyanate (HDI).

Specifically, when hexamethylene diisocyanate (HDI), rather than diisocyanate having a benzene ring, is used as the first isocyanate, it can be relatively easy to synthesize it by extending the chain length of the prepolymer. .

The first isocyanate preferably has an average NCO% of 40 to 50%.

The number average molecular weight of the prepolymer may vary depending on the composition of the composition for producing polyurethane foam. Specifically, the prepolymer is an additive to a composition for producing polyurethane foam, and the number average molecular weight can be adjusted differently by adjusting the prepolymer to have different chain lengths depending on the composition of the composition. Therefore, the number average molecular weight of the prepolymer can be adjusted differently depending on the composition of the composition for producing polyurethane foam, and the prepolymer with optimal conditions can be added to the composition.

The number average molecular weight (M _n ) of the prepolymer may be 10,000 to 150,000.

The viscosity (η) of the prepolymer may be 10 to 100 Pa·s.

In general, as the chain length of the prepolymer increases, the number average molecular weight and viscosity also increase, so the number average molecular weight and viscosity must be appropriately adjusted considering the pore size of the polyurethane foam to be ultimately manufactured and compatibility with other raw materials. It is desirable.

As the content of the first isocyanate relative to the first polyol decreases, the chain length of the linear long chain prepolymer may increase. Therefore, it is desirable to determine the input amounts of the first polyol and the first isocyanate and the chain length of the prepolymer in consideration of the characteristics of the prepolymer suitable for the composition of the composition for producing polyurethane foam to which the prepolymer is added.

The prepolymer may be formed by reacting the first polyol and the first isocyanate at a molar ratio of 1:1 to 1.5. If the molar ratio is less than 1:1, on the other hand, the prepolymer may be entangled due to an increase in chain length, which may reduce compatibility with other raw materials other than the prepolymer. If the molar ratio is greater than 1:1.5, the chain length of the prepolymer may become too short and the pore size reduction effect may be reduced.

Prepolymer manufacturing method

The method for producing a pre-polymer for producing polyurethane foam according to an embodiment of the present invention is a method for producing a pre-polymer included in a composition for producing polyurethane foam, wherein the first isocyanate and the short-chain reacting a first polyol to form a linear long-chain prepolymer, wherein the composition includes a second isocyanate; and a second polyol.

Detailed descriptions of the prepolymer, first polyol, first isocyanate, etc. are omitted since they overlap with the above description.

In the method for producing the prepolymer, the molecular weight of the prepolymer can be adjusted according to the composition of the composition for producing polyurethane foam in the step of forming the prepolymer.

Specifically, in the step of forming the prepolymer, the molecular weight can be adjusted differently by adjusting the prepolymer to have different chain lengths depending on the composition of the composition. In this case, the molecular weight of the prepolymer can be adjusted differently depending on the composition of the composition for producing polyurethane foam, and the prepolymer having optimal conditions can be added to the composition.

Forming the prepolymer includes adding a catalyst to the first polyol and then stirring to remove moisture; Adding an anhydrous compound to the first polyol from which moisture has been removed in an inert gas atmosphere; And it may include adding the first isocyanate and reacting it with the first polyol.

If moisture is substantially removed in the moisture removal step, side reactions rarely occur, so there can be a high degree of agreement between the trends in molecular weight and viscosity of the final synthesized prepolymer and the theoretically calculated values. Therefore, whether moisture has been substantially removed can be judged based on the degree to which the tendency between the molecular weight and viscosity of the final synthesized prepolymer matches the theoretically calculated value.

In the step of removing moisture by stirring after adding the catalyst to the first polyol, the stirring may be carried out in a vacuum of 50 to 200 ° C., specifically, in a vacuum of 60 to 100 ° C., and at 50 to 200 rpm. Speed, specifically, may be carried out at a speed of 80 to 120 rpm, and may be carried out for 0.5 to 5 hours, specifically, 1 to 3 hours. If stirring in the above step is carried out according to the above temperature, speed, and time, moisture in the first polyol can be removed more efficiently.

The inert gas may be one or more types of gas selected from nitrogen (N ₂ ) gas, argon (Ar) gas, and helium (He) gas. Specifically, the inert gas may be nitrogen (N ₂ ) gas. When the above-mentioned gas is applied as the inert gas, it is possible to effectively prevent moisture in the air from participating in the reaction.

When a catalyst is added in the step of forming the prepolymer, the reaction can proceed with excellent activity and the prepolymer can be synthesized. At this time, the catalyst may be dibutyltin dilaurate (DBTDL). When the above compounds are used as the catalyst, the activity of the catalyst is adequate, so side reactions occur less frequently during synthesis, and the storage stability of the synthesized resin can be excellent.

When an anhydrous compound is added to the first polyol in the step of forming the prepolymer, side reactions in which urea is formed due to the reaction between moisture and diisocyanate can be minimized. At this time, the anhydrous compound may be anhydrous dimethylformamide (DMF).

The step of adding the first isocyanate and reacting it with the first polyol may be performed with stirring. At this time, the stirring may be carried out at 50 to 200 ℃, specifically, 60 to 100 ℃, at a speed of 200 to 1,000 rpm, specifically, 300 to 700 rpm, and for 0.5 to 5 hours, specifically This may last for 1 to 3 hours. When the step of adding the first isocyanate and reacting it with the first polyol is carried out with stirring according to the above temperature, speed, and time, a prepolymer for producing polyurethane foam can be produced more efficiently.

The method for producing the prepolymer for producing polyurethane foam may further include the step of drying after a separate washing process after the reaction between the first polyol and the first isocyanate is completed. In this case, the prepolymer can be produced with better yield.

The washing process may be performed using a diethyl ether mixed solution. In this case, while the diethyl ether mixed solution cannot dissolve the product (prepolymer), it can dissolve the reactants (first polyol and first isocyanate), making it easier to remove unreacted products that did not produce a prepolymer. there is.

The drying may be carried out at 50 to 200 °C, specifically, 60 to 100 °C, and may be carried out for 12 to 60 hours, specifically, 18 to 36 hours.

The prepolymer is an additive to the composition for producing polyurethane foam and is manufactured as a main component of the composition for producing polyurethane foam, so it has excellent compatibility and does not have problems such as dispersion, and can be applied as is while maintaining the existing polyurethane production process. , the process can be upgraded to the next level without problems such as additional processes or excessive costs. In addition, a prepolymer having optimal conditions can be added depending on the composition of the composition, so it can be very useful as an additive for polyurethane foams of various compositions.

Composition for producing polyurethane foam

The composition for producing polyurethane foam according to an embodiment of the present invention may include the prepolymer, second polyol, and second isocyanate described above.

A detailed description of the prepolymer is omitted since it overlaps with the above description.

The second polyol may be a linear polyol in which repeating units are combined into one chain. Such linear polyols include polytetramethylene ether glycol (PTMEG), polypropylene glycol (PPG), and polyethylene glycol (PEG), and polyethylene glycol (PEG) is preferred.

The number average molecular weight (M _n ) of the second polyol may be 100 to 2,000. Specifically, the number average molecular weight of the second polyol may be 200 to 1,000, or 300 to 500.

The second polyol may be a compound substantially the same as the first polyol, or may be a different compound from each other.

The hydroxyl value (OH value) of the second polyol may be 350 to 550. Specifically, the hydroxyl value of the second polyol may be 400 to 500.

If the hydroxyl value of the second polyol is too low, the mechanical strength and low-temperature dimensional stability of the polyurethane foam may decrease, and if the hydroxyl value is excessively high, thermal conductivity may increase and cracking may occur. Therefore, if a second polyol having a hydroxyl value outside the above-described appropriate range is applied, it may cause defective products and reduce productivity.

The prepolymer may be included in an amount of 5 to 30 parts by weight, specifically, 7 to 15 parts by weight, based on 90 parts by weight of the second polyol. If the content of the prepolymer compared to the second polyol is too small, it is difficult to expect a substantial improvement in physical properties due to the addition of the prepolymer, and if the content is too high, the compatibility between the prepolymer and the second polyol may decrease. Therefore, when the prepolymer is included in the above amount, the effect of adding the prepolymer can be substantially obtained without compatibility problems with the second polyol.

The composition for producing polyurethane foam may further include an amine-based catalyst.

The amine-based catalyst is triethylamine, tripropylamine, triisopropanolamine, tributylamine, trioctylamine, hexadecyldimethylamine, N-methylmorpholine, N-ethylmorpholine, N-octadecylmorpholine, mono Ethanolamine, diethanolamine, dimethylethanolamine, triethanolamine, N-methyldiethanolamine, N,N-dimethylethanolamine, diethylenetriamine, N,N,N',N'-tetramethylbutanediamine, N ,N,N',N'-tetramethyl-1.3-butanediamine, N,N,N',N'-tetraethylhexamethylenediamine, bis[2-(N,N-dimethylamino)ethyl]ether, N ,N-dimethylbenzylamine, N,N-dimethylcyclohexylamine, N,N,N',N',n-pentamethyldiethylenetriamine, triethylenediamine, formic acid and other salts of triethylenediamine, No. 1 and oxyalkylene adducts with amino groups of secondary amines, azacyclic compounds such as N,N-dialkylpiperazines, and β of various N,N',N''-trialkylaminoalkylhexahydrotriazines. -It may be one or more amine-based urethanization catalysts selected from aminocarbonyl catalysts.

Specifically, the amine-based catalyst may be N,N-dimethylcyclohexylamine (PC-8). If the amine-based catalyst is like this, it can simultaneously promote gelation and foaming during the urethane reaction, and the activity of the catalyst can be appropriate to reduce side reactions during synthesis.

The amine-based catalyst may be included in an amount of 3 to 10 parts by weight based on 90 parts by weight of the second polyol. Specifically, the amine-based catalyst may be included in an amount of 3.5 to 5 parts by weight based on 90 parts by weight of the second polyol.

When the content of the amine-based catalyst is as above, the speed of the urethane reaction can be further increased to quickly promote the creation of fine-sized pores, and the pore size of the polyurethane foam can be further reduced.

The composition for producing polyurethane foam may further include a surfactant. Specifically, the composition for producing polyurethane foam may further include an organic silicon-based compound as a surfactant. The organic silicon-based compound may include a polyalkylene glycol silicone copolymer.

When the composition for producing polyurethane foam further includes such a surfactant, the pore size can be more easily adjusted and the pore structure can be further stabilized.

The surfactant may be included in an amount of 1 to 5 parts by weight based on 90 parts by weight of the second polyol. Specifically, the surfactant may be included in an amount of 1.5 to 3 parts by weight based on 90 parts by weight of polyol.

The composition for producing polyurethane foam may further include a blowing agent.

The foaming agent vaporizes and causes foaming due to the heat of reaction resulting from the urethane reaction between polyol and isocyanate, and can contribute to producing polyurethane foam, which is a foam.

The foaming agent may be an olefin-based foaming agent.

The olefin-based blowing agent is a hydrofluoro olefin (HFO)-based blowing agent, and may be one or more selected from HFO-1233zd, HFO-1234ze, and HFO-1234yf. Specifically, the olefin-based blowing agent may be HFO-1233zd.

Previously, hydrofluorocarbon (HFC)-based foaming agents have been widely used as foaming agents for polyurethane foam production, but their high GWP (Global Warming Potential) value causes ozone layer destruction and global warming. Due to environmental problems, its use is virtually prohibited. Therefore, when the above-mentioned olefin-based foaming agent is applied as a foaming agent for polyurethane foam production, not only can it have equivalent or higher foaming performance, but it can also have better usability because there are no restrictions due to environmental issues.

The olefin-based blowing agent may be included in an amount of 1 to 20 parts by weight based on 90 parts by weight of the second polyol. Specifically, the olefin-based blowing agent may be included in an amount of 5 to 10 parts by weight based on 90 parts by weight of the second polyol.

If the content of the olefin-based foaming agent is too small, the foaming phenomenon does not occur properly, making it difficult to form pores, and there may be difficulties in controlling the density of the polyurethane foam. On the other hand, if the content is too large, excessive formation of bubbles may promote coalescence of pores, increase pore size and nucleation rate, and reduce the insulation and durability of polyurethane foam. Therefore, when the content of the olefin-based blowing agent is adjusted within the range described above, pores with a small cell size can be easily formed, making it possible to manufacture polyurethane foam that is excellent in both heat insulation and durability.

The second isocyanate is a compound having two or more isocyanate groups (NCO) and may be hexamethylene diisocyanate (HDI), polymethylene diphenyl diisocyanate (poly-MDI), toluene diisocyanate (TDI), etc.

Specifically, the second isocyanate may be polymethylene diphenyl diisocyanate (Poly-MDI) having a functional group number of 2.6 to 3. The polymethylene diphenyl diisocyanate has a structure suitable for forming a polyurethane structure, and can contribute to manufacturing polyurethane foam more easily.

The second isocyanate may be a compound substantially the same as the first isocyanate, or may be a different compound from each other.

The second isocyanate preferably has an average NCO% of 29 to 32%.

If the NCO% of the second isocyanate component is less than 29%, the fluidity of the manufactured polyurethane foam may decrease, and if it exceeds 32%, low-temperature dimensional stability may decrease. Therefore, when the average NCO% of the second isocyanate is 29 to 32%, polyurethane foam with excellent fluidity and stability can be manufactured.

The composition for producing polyurethane foam may have an isocyanate index (NCO index) of 100 to 150. Specifically, the composition for producing polyurethane foam may have an isocyanate index (NCO index) of 110 to 130.

Depending on the isocyanate index value, the number of urethane bonds may vary, and there may also be differences in the physical properties of the polyurethane foam produced. In theory, the most ideal physical properties are shown when the isocyanate index value is 100, but when actually synthesizing polyurethane, isocyanate may be lost due to residual moisture in the polyol, so it is desirable to add isocyanate in an appropriate excess compared to the theoretical content. Therefore, when the isocyanate index value of the composition for producing polyurethane foam is as above, it is possible to manufacture polyurethane foam having ideal physical properties by having an isocyanate index value (100) in theory.

polyurethane foam

The polyurethane foam according to one embodiment of the present invention may have an effective nucleation density (N _eff ) of 20,000 to 50,000/mg according to Equation 1 below. Specifically, the polyurethane foam may have an effective nucleation density (N _eff ) of 25,000 to 40,000/mg.

[Equation 1]

In Equation 1, V _f corresponds to the reciprocal of the density (ρ _f ) of the polyurethane foam, and V _p is the average volume of pores of the polyurethane foam according to Equation 2 below.

[Equation 2]

In Equation 2 above, D is the pore diameter of the polyurethane foam.

The effective nucleation density (N _eff ) is a parameter that quantifies the nucleation rate of polyurethane foam and means the number of nuclei generated per unit mass (mg) of polyurethane foam. At this time, the V _f can be calculated by taking the reciprocal of the density (ρ _f ) of the polyurethane foam measured as the specific volume of the produced polyurethane foam, and the V _p is the polyurethane foam pores in the shape of a sphere. Assuming that it has , the volume of these spheres can be calculated through the measured pore diameter (D) of the polyurethane foam.

When the effective nucleation density (N _eff ) of the polyurethane foam is as described above, the polyurethane foam may have better insulation properties, durability, etc. due to the improved nucleation rate.

The density (ρ _f ) of the polyurethane foam may be 60 to 100 kg/m ³ . Specifically, the density (ρ _f ) of the polyurethane foam may be 60 to 70 kg/m ³ .

The pore diameter (D) of the polyurethane foam may be 50 to 150 um. Specifically, the pore diameter (D) of the polyurethane foam may be 70 to 120 um.

When the density (ρ _f ) and pore diameter (D) of the polyurethane foam are as described above, the nucleation rate of the polyurethane foam can be further improved, and polyurethane foam with more improved properties can be provided.

The polyurethane foam may be manufactured from a composition for producing polyurethane foam containing the prepolymer described above.

The method for producing polyurethane foam according to an embodiment of the present invention can produce polyurethane foam using a composition for producing polyurethane foam containing the prepolymer described above.

Hereinafter, the present invention will be described in more detail through examples. However, the following example shows an example of the present invention, and the present invention is not limited thereto.

Examples and Comparative Examples

1. Prepolymer for manufacturing polyurethane foam

1) Prepolymer synthesis

Add polyethylene glycol (PEG; Mn = 400) as a short-chain first polyol to a glass bottle, add dibutyltin dilaurate (DBTDL) catalyst to the glass bottle, and process in a vacuum at 80°C. The mixture was stirred for 2 hours at a stirring speed of 100 rpm to remove moisture. Afterwards, the inside of the glass bottle was created in a nitrogen environment and anhydrous dimethylformamide (DMF) was added. Afterwards, hexamethylene diisocyanate (HDI) was added as the first isocyanate, and urethane reaction was carried out for 2 hours while stirring at 500 rpm at a reaction temperature of 80 ° C to grow the chain length. After the reaction was completed, the washing process was repeated with the diethyl ether mixed solution, and then the remaining diethyl ether mixed solution was dried in an oven at 70 ° C. for 24 hours to obtain the prepolymers of Synthesis Examples 1 to 4. did. The molar ratio and weight ratio of the first polyol and first isocyanate added in Synthesis Examples 1 to 4 are shown in Table 1 below.

2) Evaluation of prepolymer physical properties

For the prepolymers of Synthesis Examples 1 to 4, the number average molecular weight (M _n ) value was measured using a MALDI TOF mass spectrometer, and the viscosity ([η]) was measured using a rheometer (MCR 302). The results are shown in Table 1 below. As a result of the measurement, it was confirmed that a prepolymer having a number average molecular weight of 10,000 to 150,000 and a viscosity of 10 to 100 Pa·s depending on the composition ratio of the reactant was synthesized.

It was confirmed through the molecular weight and viscosity data in Table 1 below that the chain length of the prepolymer varies depending on the composition ratio of the reactants used to prepare the prepolymers of Synthesis Examples 1 to 4, and the chain length of the prepolymer was adjusted by adjusting the composition ratio of the reactants. It was confirmed that control was possible.

prepolymer mole ratio (mol)
/ Weight ratio (g) NCO ratio Number average molecular weight (M _n ) Viscosity (η) Primary polyol: Primary isocyanate Synthesis Example 1 1: 1.40
/ 10: 5.89 1.4 11,231 16.1 Synthesis Example 2 1: 1.20
/ 10: 5.05 1.2 18,940 22.8 Synthesis Example 3 1: 1.10
/ 10: 4.63 1.1 41,176 43.6 Synthesis Example 4 1: 1.05
/ 10: 4.42 1.05 108,410 82.0

2. Polyurethane foam

1) Composition for manufacturing polyurethane foam and manufacturing polyurethane foam

Among the prepolymers of Synthesis Examples 1 to 4, the prepolymer of Synthesis Example 4, which had the longest chain length, was applied as the prepolymer of Example 1, and polyol (hydroxyl value (OH value): 425, number average molecular weight (M _{n- )} : 400), amine catalyst (Dimethyl cyclohexyl amine (DMCHA); PC-8), silicone surfactant (TEGOSTAB® B 8404), and HFO-1233zd as a blowing agent were mixed in the weight ratio shown in Table 2 to prepare solution A. did. Next, solution B was prepared by adding polymethylene diphenyl diisocyanate (poly-MDI; NCO %=31.4%) to solution A. At this time, the amount of isocyanate added was applied so that the final isocyanate index (NCO index) value was 120%. Afterwards, solution B was mixed and foamed for 10 to 15 seconds at a speed of 1400 rpm using an electric drill to prepare the polyurethane foam of Example 1 (please confirm).

Composition composition (parts by weight) secondary polyol 90 prepolymer 10 Amine-based catalyst 4 silicone surfactant 2.5 blowing agent 8 Secondary isocyanate* 121 Isocyanate index (NCO index; %) = 120

The other conditions as in Example 1 were the same, but instead of the prepolymer, polyethylene glycol (PEG), a linear polymer with a number average molecular weight of 4,000,000, was added in an amount of 3 parts by weight based on 90 parts by weight of the second polyol. Polyurethane foam was manufactured.

In addition, the polyurethane foam of Comparative Example 1 was manufactured under the same conditions as Example 1 except for adding the prepolymer.

2) Evaluation of physical properties of polyurethane foam

(1) Density (ρ _f ) measurement

After cutting the prepared polyurethane foam into a rectangular parallelepiped shape, the width, length, and height of the rectangular parallelepiped were measured to calculate the volume of the polyurethane foam of the rectangular parallelepiped shape. Afterwards, the mass of the rectangular polyurethane foam was measured using a scale, the final density value was calculated, and the results are shown in FIG. 5.

(2) Measurement of pore size (diameter; D)

After plating the sample with platinum to impart conductivity to the manufactured polyurethane foam, the cells were observed using a Hitachi S4800 scanning electron microscope (SEM) in a 10 kV environment, and the results are shown in Figure 2. In addition, more than 200 pore diameters of each polyurethane foam were measured, and their average values are shown in Figure 4.

(3) Effective nucleation density (N _eff ) calculate

The effective nucleation density (N _eff ) value was calculated according to Equations 1 and 2 below based on the density and pore size values measured for each polyurethane foam, and the results are shown in FIG. 3.

[Equation 1]

In Equation 1, V _f corresponds to the reciprocal of the density (ρ _f ) of the polyurethane foam, and V _p is the average volume of pores of the polyurethane foam according to Equation 2 below.

[Equation 2]

In Equation 2 above, D is the pore diameter of the polyurethane foam.

Referring to Table 2 and Figures 2 to 4, the polyurethane foam of Example 1 has smaller pore sizes and a higher nucleation density compared to Comparative Example 1 without the addition of a linear long-chain prepolymer. It was found that This is believed to be because the prepolymer suppresses the growth of nuclei formed during the foaming process and can also greatly suppress the occurrence of pore fusion (coalescence). In addition, Example 1, in which a prepolymer was added, was found to have physical properties within a substantially similar range to the polyurethane foam in Example 2, in which PEG, whose number average molecular weight was one order of magnitude higher than that of the prepolymer, was added. Therefore, it is believed that when the prepolymer of the present invention with a relatively low molecular weight is added as in Example 1, polyurethane foam with excellent physical properties can be manufactured more efficiently.

Considering the above, it is believed that polyurethane foam manufactured by adding a linear long chain prepolymer will have excellent thermal insulation performance due to its small pore size and large nucleation rate, and the prepolymer can be used as an additive. Because it is used, it is expected that the existing polyurethane manufacturing process can be maintained and economic feasibility can be secured. In addition, it is possible to appropriately control the chain length and elongation viscosity by adjusting the composition ratio of the reactants used to produce the prepolymer, so it is believed that it will be possible to add a prepolymer with optimal conditions to polyurethanes with different compositions. do.

Claims (10)

As a prepolymer contained in a composition for producing polyurethane foam,
The prepolymer is in a linear long-chain form formed by reacting a short-chain first polyol with a first isocyanate,
The composition includes a second polyol and a second isocyanate,
Prepolymer for manufacturing polyurethane foam.
According to paragraph 1,
The number average molecular weight is different depending on the composition of the composition for producing polyurethane foam,
Prepolymer for manufacturing polyurethane foam.
According to paragraph 1,
The number average molecular weight of the prepolymer is 10,000 to 150,000,
Prepolymer for manufacturing polyurethane foam.
According to paragraph 1,
The prepolymer is formed by reacting the first polyol and the first isocyanate at a molar ratio of 1: 1 to 1.5,
Prepolymer for manufacturing polyurethane foam.
A method for producing a pre-polymer contained in a composition for producing polyurethane foam,
Comprising the step of reacting a first isocyanate and a short-chain first polyol to form a linear long-chain prepolymer,
The composition includes a second isocyanate; And comprising a second polyol,
Method for producing prepolymer for producing polyurethane foam.
According to clause 5,
In the step of forming the prepolymer,
Adjusting the molecular weight of the prepolymer according to the composition of the composition for producing polyurethane foam,
Method for producing prepolymer for producing polyurethane foam.
According to clause 5,
The step of forming the prepolymer is,
Adding a catalyst to the first polyol and then stirring to remove moisture;
Adding an anhydrous compound to the first polyol from which moisture has been removed in an inert gas atmosphere; and
Comprising the step of adding the first isocyanate and reacting it with the first polyol,
Method for producing prepolymer for producing polyurethane foam.
Producing polyurethane foam with a composition for producing polyurethane foam containing the prepolymer according to any one of claims 1 to 4,
Polyurethane foam manufacturing method.
A polyurethane foam manufactured from a composition for producing polyurethane foam containing the prepolymer according to any one of claims 1 to 4,
The polyurethane foam,
The apparent nucleation density (N _eff ) according to Equation 1 below is 20,000 to 50,000/mg,
polyurethane foam;
[Equation 1]

In Equation 1, V _f corresponds to the reciprocal of the density (ρ _f ) of the polyurethane foam, and V _p is the average volume of pores of the polyurethane foam according to Equation 2 below;
[Equation 2]

In Equation 2 above, D is the pore diameter of the polyurethane foam.
According to clause 9,
The pore diameter (D) of the polyurethane foam is 50 to 150 um,
Polyurethane foam.