JP7119821B2 - Composition for rigid polyurethane foam and method for producing rigid polyurethane foam - Google Patents

Description

The present invention relates to a composition for rigid polyurethane foam and a method for producing rigid polyurethane foam.

BACKGROUND ART Rigid polyurethane foams are widely used as insulation materials for refrigerators, freezer warehouses, building materials, etc., and for spray applications because of their excellent thermal insulation performance, dimensional stability and workability.

On the other hand, it is known that the thermal conductivity of rigid polyurethane foam increases over time and the heat insulation performance decreases.

The thermal conductivity of the gas inside the cells increases as the thermal insulation gas inside the foam cells diffuses out of the system and air with higher thermal conductivity flows into the foam cells. caused by

Maintaining high thermal insulation performance over the entire life cycle of products is an important issue from the viewpoint of energy conservation, and the development of thermal insulation materials with little deterioration in thermal insulation performance over time is desired.

In particular, in a laminate board using a soft surface material having high air permeability, the rigid polyurethane foam itself is required to have high gas barrier properties.

In order to address the above problem, Patent Document 1 discloses a technique for improving the gas barrier properties of a bubble film by dispersing layered silicate in polyol on a nanoscale. However, solid additives accelerate the wear of equipment such as a mixing discharge head and a liquid feed pump in a foam production site, and place a heavy burden on the equipment, which is not preferable.

Further, Patent Literature 2 discloses a technique for increasing the number of barriers against invasion of air from the atmosphere and improving gas barrier properties by controlling the size and shape of foam cells. However, in order to control the cell shape, a method of applying a pressure higher than the foaming pressure for a certain period of time during the foaming process and then releasing the pressure is adopted, which complicates the foam manufacturing process.

Japanese Patent Application Laid-Open No. 2004-339437 Japanese Patent Application Laid-Open No. 2007-332203

The present invention has been made based on the above circumstances, and its object is to provide heat insulation performance over time that can be produced with general foam production equipment without including complicated processes in the production of rigid polyurethane foam. To obtain a rigid polyurethane foam with less deterioration.

As a result of repeated studies, the present inventors have found that the above problems can be solved by using a specific polyol composition and a specific isocyanate group-terminated prepolymer, and have completed the present invention.

That is, the present invention includes the following embodiments.

(1) A rigid polyurethane comprising a polyol composition (E) containing a polyol component (A), a catalyst (B), a foam stabilizer (C), and a blowing agent (D), and an isocyanate group-terminated prepolymer (F) A foam composition, wherein the polyol component (A) contains a phthalic acid-based polyester polyol having an average functionality of 2.0 to 2.5, and the isocyanate group-terminated prepolymer (F) is combined with the isocyanate composition (G). An isocyanate group-terminated prepolymer having a viscosity of 800 to 5000 mP s at 20 ° C. obtained from a polyol (H), the isocyanate composition (G) containing monomeric MDI and polymeric MDI, and having an average number of functional groups is 2.2 to 2.6, and the polyol (H) is a phthalate polyester diol.

(2) A rigid polyurethane foam obtained from the composition for rigid polyurethane foam described in (1) above.

(3) A method for producing a rigid polyurethane foam, comprising reacting and foaming the rigid polyurethane foam composition according to (1) above.

(4) A laminate board composed of the rigid polyurethane foam described in (2) above and a breathable soft surface material.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a rigid polyurethane foam that exhibits little deterioration in thermal insulation performance over time without including a complicated post-treatment step in the foam production process.

Embodiments of the present invention are described below.

The rigid polyurethane foam composition of the present invention comprises a polyol composition (E) and an isocyanate group-terminated prepolymer (F).

The polyol composition (E) in the present invention contains a polyol component (A), a catalyst (B), a foam stabilizer (C), and a foaming agent (D), and the isocyanate group-terminated prepolymer (F) is It is obtained from the isocyanate composition (G) and the polyol (H).

<Polyol component (A)>
The polyol component (A) contained in the polyol composition (E) of the present invention includes, for example, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, Pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α,β-diethyl Dicarboxylic acids such as succinic acid, maleic acid, fumaric acid, or one or more kinds of anhydrides thereof, and ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1, 3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol , 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A , bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, and other low molecular weight polyols having a molecular weight of 500 or less. It contains at least one of acid, isophthalic acid, terephthalic acid and anhydrides thereof as an acid component. The average functionality of the polyol component (A) is 2.0 to 2.5, preferably 2.0. If the average number of functional groups exceeds 2.5, the cross-linking point concentration in the composition for rigid polyurethane foam becomes excessive, so that the completion rate of the trimerization reaction of the isocyanate group is lowered, and the gas barrier properties of the cell membrane are lowered.

<Catalyst (B)>
As the catalyst (B), various urethanization catalysts, isocyanuration catalysts and the like known in the art can be used, and it is preferable to use a urethanization catalyst and an isocyanuration catalyst together.

Examples of urethanization catalysts include triethylenediamine, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, and N,N,N',N'',N''-pentamethyldiethylenetriamine. , N,N,N′,N″,N′″,N′″-hexamethyltriethylenetetramine, bis(dimethylaminoethyl) ether, 1,3,5-tris(N,N-dimethylamino propyl)hexahydro-S-triazine, 2,4,6-tris(dimethylaminomethyl)phenol, 2,4-bis(dimethylaminomethyl)phenol, N-dimethylaminoethyl-N'-methylpiperazine, N,N, amine compounds such as N',N'-tetramethylhexamethylenediamine, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, N,N-dimethylaminopropylamine, bis(dimethylaminopropyl)amine; N,N-dimethylaminoethanol, N,N,N'-trimethylaminoethylethanolamine, 2-(2-dimethylaminoethoxy)ethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether , N-(3-dimethylaminopropyl)-N,N-diisopropanolamine, N-(2-hydroxyethyl)-N'-methylpiperazine, N,N-dimethylaminohexanol, 5-dimethylamino-3-methyl Examples include alkanolamines such as -1-pentanol, etc. These urethanization catalysts may be used alone, or two or more of them may be used in combination.

Examples of isocyanurate-forming catalysts include quaternary ammonium salts, alkali metal salts of carboxylic acids having 2 to 12 carbon atoms, alkali metal salts of acetylacetone and salicylaldehyde, Lewis acid complex salts of amines, and metal catalysts. can be done.

The amount of the catalyst (B) added to the composition for rigid polyurethane foam of the present invention is 0.1 to 1.0% by mass for the urethanization catalyst and 0.1 to 2.0% by mass for the isocyanuration catalyst. % by mass is preferred.

<Foam stabilizer (C)>
Examples of the foam stabilizer (C) include commercially available foam stabilizers used for producing polyurethane foams. The foam stabilizer (C) is not particularly limited. system surfactants and the like. These surfactants are not particularly limited. , B8460, B8462, B8465, B8466, B8467, B8481, B8484, B8485, B8486, B8496, B8870, B8871, Dow Corning Toray SZ-1328, SZ-1642, SZ-1677, SH-193, Air Products DC-193, DC5598, etc. manufactured by K.K.

The amount of the foam stabilizer (C) to be added is preferably in the range of 0.1 to 5% by mass in the composition for rigid polyurethane foam of the present invention. If it is less than the lower limit, the cell structure and cell size may not be stable, and a uniform foam may not be obtained.

<Foaming agent (D)>
As the foaming agent (D), water as a chemical foaming agent and a physical foaming agent are used in combination. Water reacts with isocyanate groups to generate carbon dioxide gas, which can cause foaming.

Conventionally known physical foaming agents such as hydrocarbon compounds, HFCs, and HFOs can be used, but HFOs are particularly preferred from the viewpoint of environmental load and heat insulating performance. Examples of HFOs include HFO-1233zd, HFO-1336mzz and the like, each of which may be used alone or in combination.

The amount of the foaming agent added is preferably 0.8 to 1.5 mmol/g in the composition for rigid polyurethane foam as the total amount of water and physical foaming agent. It is preferred that the molar fraction is between 0.4 and 0.8.

In the present invention, plasticizers, flame retardants, colorants, etc., which are commonly used for polyurethane foams, can be used as additives as required.

<Isocyanate composition (G)>
The isocyanate composition (G) contained in the isocyanate-terminated prepolymer (F) contains monomeric MDI and polymeric MDI, and has an average functional group number of 2.2 to 2.6 as determined from the NCO content and number average molecular weight. is.

If the average number of functional groups is less than 2.2, the diameter of the cells in the foam will increase, resulting in an increase in the initial value of thermal conductivity due to increased radiation heat transfer and deterioration in gas barrier properties due to a decrease in the number of barriers.

If the average number of functional groups exceeds 2.6, the cross-linking point concentration in the composition for rigid polyurethane foam becomes excessive, so that the rate of completion of the trimerization reaction of the isocyanate groups decreases, resulting in a decrease in the gas barrier properties of the cell membrane.

<Polyol (H)>
The polyol (H) contained in the isocyanate group-terminated prepolymer (F) includes, for example, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, and pimelic acid. , suberic acid, glutaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α,β-diethylsuccinic acid , Maleic acid, fumaric acid and one or more of dicarboxylic acids or their anhydrides, and ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3- butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3 , 3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis A polyester diol having an average functionality of 2.0 obtained from a polycondensation reaction with one or more bifunctional low-molecular-weight polyols having a molecular weight of 500 or less, such as (β-hydroxyethyl)benzene and xylylene glycol, and phthalic acid. , isophthalic acid, terephthalic acid, or anhydrides thereof as an acid component.

The isocyanate group-terminated prepolymer (F) obtained from the isocyanate composition (G) and the polyol (H) as described above has a viscosity at 20° C. of 800 to 5000 mPa·s, preferably 1000 to 4000 mPa·s. . If the viscosity at 20° C. is less than 800 mPa·s, the diameter of the cells in the foam will increase, resulting in an increase in the initial value of thermal conductivity due to increased radiation heat transfer and deterioration in gas barrier properties due to a decrease in the number of barriers. On the other hand, when the viscosity exceeds 5000 mPa·s, the fluidity of the reaction liquid becomes insufficient, resulting in deterioration of filling properties.

Next, a method for producing a rigid polyurethane foam according to the present invention will be described.

The rigid polyurethane foam of the present invention can be obtained by reacting and foaming the composition for rigid polyurethane foam described above.

Specifically, the polyol composition (E) and the isocyanate group-terminated prepolymer (F) are stirred and mixed at a liquid temperature of, for example, 15 to 50° C., preferably 20 to 30° C., and then placed in a mold or the like. A rigid polyurethane foam can be obtained by the introduction.

At that time, the ratio of the isocyanate group (hereinafter also referred to as NCO group) of the isocyanate group-terminated prepolymer (F) to the active hydrogen group (hereinafter also referred to as OH group) of the polyol composition (E) is the NCO group and the OH The group equivalent ratio (NCO group/OH group) is preferably in the range of 1.5 to 4.0, particularly preferably in the range of 2.0 to 3.0.

Any device can be used for producing a rigid polyurethane foam as long as the raw material liquids can be uniformly mixed. For example, when manufacturing small mixers and general urethane foam, low-pressure or high-pressure foaming machines for injection foaming, low-pressure or high-pressure foaming machines for slab foaming, low-pressure or high-pressure foaming machines for continuous lines, and spraying work For example, a spray foaming machine can be used.

The method of adhering and providing the face material on both sides of the rigid polyurethane foam can be appropriately selected from conventionally known methods. For example, a rigid polyurethane foam may be obtained by die molding or the like, and face materials may be adhered to both surfaces of the obtained rigid polyurethane foam material by a press method. In addition, a so-called roll-to-roll method or a similar roll-to-roll method, which is commonly used, can be used.

In this roll-to-roll method or a roll-to-roll similar method, a raw material liquid of a rigid urethane foam material is supplied between a lower surface material and an upper surface material supplied from a lower winding roll and an upper winding roll, and foaming is performed. It is molded. Forming is a method of arranging a lower belt conveyor under the lower face member and an upper belt conveyor above the upper face member, respectively.

The rigid polyurethane foam sandwiched between the resulting facings may be wound at one end on a take-up roll, such as in a roll-to-roll system, if it is windable, or the resulting insulation may be sized immediately after molding. It may be cut to form a panel.

In the present invention, a soft surface material having high air permeability and moisture permeability can be preferably used. Examples of the soft surface material having high air permeability and moisture permeability include kraft paper, polyester nonwoven fabric, glass nonwoven fabric, and the like.

For example, the composition for rigid polyurethane foam is continuously discharged onto a breathable soft surface material installed on a lower conveyor with a width of 110 cm, which runs at 5 m / min, and the breathable flexible sheet installed at the bottom of the upper conveyor. A rigid polyurethane foam sandwiched between air-permeable soft surface materials can be obtained by foaming with the surface materials.

The rigid polyurethane foam of the present invention obtained in this way has excellent gas barrier properties of the foam itself, so even if the surface material has high air permeability, the gas composition inside the foam cells changes little over time. , it is possible to maintain high heat insulation performance for a long period of time.

Molded articles using the rigid polyurethane foam obtained by the present invention can be suitably used for roofs and walls of buildings, underground structures, floorboards of bridges, water tanks, tanks, and the like.

The present invention will be described in more detail with reference to Examples, but the present invention is not limited by these Examples. In the examples and comparative examples, all "%" means "% by mass" and all "parts" means "parts by mass".

<Preparation of isocyanate group-terminated prepolymer>
After purging a reactor equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a temperature controller, 80 g of MR-200, 20 g of Millionate NM, and 11.1 g of polyol a are charged and stirred at 70° C. for 3 hours. Thus, an isocyanate group-terminated prepolymer F-1 was obtained. Isocyanate group-terminated prepolymers F-2 to F-9 were prepared in the same manner as the isocyanate group-terminated prepolymer F-1 with the formulations shown in Table 1.

The raw materials used in Table 1 are shown below.
・ MR-200: Polymeric MDI isocyanate content 30.5%, average functional group number 2.73 (trade name, manufactured by Tosoh Corporation)
Millionate NM: Monomeric MDI isocyanate content 33.5%, average functional group number 2.0 (trade name, manufactured by Tosoh Corporation)
Polyol a: polyester polyol obtained from orthophthalic acid and terephthalic acid and ethylene glycol and diethylene glycol average functionality 2.0, hydroxylation 250 (mg KOH/g).

<Preparation of polyol composition>
After purging a reactor equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a cooling tube, 100 g of polyol a, 48 g of TMCPP, 3 parts of L-6643, 1.8 parts of DMCHA, and 4.8 of TRX. 4.8 parts of water and 34.6 parts of HFO-1233zd were added, and the mixture was stirred at 20° C. for 0.5 hour to obtain a polyol composition E-1. Polyol compositions E-2 to E-4 were also prepared in the same manner as polyol composition E-1 with the formulations shown in Table 2.

The raw materials used in Table 2 are shown below.
Polyol a: polyester polyol obtained from orthophthalic acid and terephthalic acid and ethylene glycol and diethylene glycol average functionality 2.0, hydroxylation 250 (mgKOH/g)
Polyol b: polyester polyol obtained from orthophthalic acid and terephthalic acid and ethylene glycol, diethylene glycol and glycerin average functionality 2.5, hydroxylation 350 (mgKOH/g)
- Polyol c: Polyether polyol obtained by adding propylene oxide to initiator glycerin Average functional group number = 3.0, hydroxylation 560 (mgKOH/g)
- Polyol d: Polyether polyol obtained by adding propylene oxide to propylene glycol as an initiator Average functional group number = 2.0, hydroxylation 280 (mgKOH/g)
- DMCHA: N,N'-dimethylcyclohexylamine (Kaolyzer No. 10 (trade name), manufactured by Kao Corporation)
・ TRX: quaternary ammonium salt (TOYOCAT-TRX (trade name), manufactured by Tosoh Corporation)
・ L-6643: Silicone foam stabilizer (trade name, manufactured by MOMENTIVE)
・TMCPP: tris(chloropropyl) phosphate (trade name, manufactured by Daihachi Chemical Co., Ltd.)
· HFO-1233zd: Hydrofluoroolefin (solsticeLBA (trade name), manufactured by Honeywell Japan).

<Examples 1 to 7, Comparative Examples 1 to 4>
An air-permeable soft glass nonwoven fabric surface material was attached in advance to the inner surface of an aluminum mold (height 250 mm, width 250 mm, thickness 50 mm) equipped with a lid, and the temperature was adjusted to 60°C in a constant temperature bath.

According to the formulation shown in Table 3, the polyol composition E-1 whose liquid temperature was adjusted to 20° C. and the isocyanate group-terminated prepolymer F-1 were stirred and mixed for 5 seconds at 6000 rpm using a lab mixer, and the foam density was 39 kg. /m ³ was injected into the mold, the lid was immediately closed, heat-cured for 20 minutes in a constant temperature bath at 60°C, and the mold was removed to obtain a laminate board with face material. The skin layer on the side surface of the resulting board was immediately cut off to a size of 200 mm×200 mm×50 mm, and a panel for thermal conductivity measurement of Example 1 was obtained. For Examples 2 to 7 and Comparative Examples 1 to 4, according to the formulations shown in Table 3, laminate boards with face materials for evaluation were similarly obtained.

<Evaluation method>
Each evaluation method in Table 3 is shown below.

[Viscosity of isocyanate group-terminated prepolymer]
The viscosity of the isocyanate group-terminated prepolymer at 20° C. was measured with a B-type rotational viscometer.

[Thermal conductivity]
Measurement was performed at an average temperature of 23° C. using Auto λHC-074/314 manufactured by Eiko Seiki Co., Ltd. according to the heat flow meter method specified in JIS A1412. The measured thickness was the thickness of the panel, and the thickness was measured with the upper and lower surface materials attached. The initial value of thermal conductivity was measured immediately after demolding. H. was stored in a constant temperature and humidity room for one year, and the thermal conductivity was measured after the lapse of time. If the rate of change in thermal conductivity after one year of aging is less than 10% of the initial value, it can be said to be good.

<Evaluation results>
- In Examples 1 to 7, the rate of change in thermal conductivity after one year of aging was less than 10% of the initial value, indicating good retention of heat insulation performance.
In Comparative Example 1, since the isocyanate group-terminated prepolymer viscosity was less than 800, the initial value of thermal conductivity was high, and the change in thermal conductivity over time was large.
In Comparative Example 2, since the number of functional groups of the isocyanate composition exceeded 2.6, although the initial value of thermal conductivity was low, the change in thermal conductivity over time increased.
In Comparative Example 3, since the number of functional groups of the isocyanate composition was less than 2.2, the initial value of thermal conductivity was high, and the change in thermal conductivity over time was large.
In Comparative Example 4, since the polyol component (A) contained in the polyol composition (E) was polyether-based, the gas barrier property was lowered and the thermal conductivity varied greatly over time.

Claims (4)

A composition for rigid polyurethane foam comprising a polyol composition (E) containing a polyol component (A), a catalyst (B), a foam stabilizer (C) and a foaming agent (D), and an isocyanate group-terminated prepolymer (F) wherein the polyol component (A) contains a phthalic acid-based polyester polyol having an average functionality of 2.0 to 2.5, and the isocyanate group-terminated prepolymer (F) is an isocyanate composition (G) and a polyol (H ) is an isocyanate group-terminated prepolymer having a viscosity of 800 to 5000 mP s at 20 ° C., the isocyanate composition (G) containing monomeric MDI and polymeric MDI, and having an average functional group number of 2. 2 to 2.6, and the polyol (H) is a phthalate-based polyester diol. A rigid polyurethane foam obtained from the rigid polyurethane foam composition according to claim 1 . A method for producing a rigid polyurethane foam, comprising reacting and foaming the rigid polyurethane foam composition according to claim 1 . A laminate board comprising the rigid polyurethane foam according to claim 2 and a breathable soft surface material.