Polyisocyanurate Foam

Abstract

To provide a polyisocyanurate foam excellent in buckling performance, and having predetermined sound absorbency.SOLUTION: According to embodiments, a polyisocyanurate foam is provided. The polyisocyanurate foam is obtained by foaming in a reaction system containing a polyol, a polyisocyanate, a foam stabilizer, a catalyst and a blowing agent. The polyol has a weight average molecular weight in the range of 3000 to 12000 and contains a polyol A having an ethylene oxide content of 50 wt.% or more, and a polyol B having a weight average molecular weight of 1000 to 8000, and a content of the ethylene oxide of less than 20 wt.%. An isocyanate index in the reaction system is 200 or more and 350 or less. A hysterisis loss rate is 90% or more.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to polyisocyanurate foams. [Background technology]

[0002] Conventionally, shock absorbing materials have been installed inside automobile doors, around the ceiling, and inside the pillars to protect passengers from external shocks while in the automobile. Known shock absorbing materials include, for example, rigid polyurethane foam and foamed thermoplastic resin beads.

[0003] Shock absorbers installed in today's automobiles are required to have not only high shock absorption performance (buckling resistance), but also excellent sound absorption performance to increase the quietness of the vehicle interior. Rigid polyurethane foam and thermoplastic resin bead foams generally have a closed-cell structure, so even if they have a predetermined shock absorption performance, they may have poor sound absorption performance. While there is a known technique for increasing the open-cell structure to improve the sound absorption performance of foams, if the hardness of the foam is not properly adjusted at the same time as increasing the open-cell structure, the shock absorption performance may be poor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-047338 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-272806 [Patent Document 3] Patent No. 4461453 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyisocyanurate foam having excellent buckling properties and predetermined sound absorbing performance. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a polyisocyanurate foam. The polyisocyanurate foam is obtained by foaming in a reaction system containing a polyol, a polyisocyanate, a foam stabilizer, a catalyst, and a blowing agent. The polyol includes polyol A having a weight-average molecular weight in the range of 3,000 to 12,000 and an ethylene oxide content of 50% by weight or more, and polyol B having a weight-average molecular weight of 1,000 to 8,000 and an ethylene oxide content of less than 20% by weight. The weight ratio of polyol A to the total weight of polyol is within a range of 65% to 85% by weight, and the weight ratio of polyol B to the total weight of polyol is within a range of 15% to 35% by weight. The isocyanate index in the reaction system is 200 or more and 350 or less. The hysteresis loss rate is 90% or more. The hysteresis loss rate is measured by a method including cutting out a measurement sample having dimensions of 50 mm x 50 mm x 50 mm from the polyisocyanurate foam, compressing the measurement sample along the foam height direction of the polyisocyanurate foam to a reference thickness at which a load of 5 N is applied using an 80φ compression tool, compressing the measurement sample along the foam height direction at a rate of 50 mm / min until the thickness displacement from the reference thickness reaches 70%, and then immediately returning the measurement sample along the foam height direction at a rate of 50 mm / min until the thickness displacement from the reference thickness reaches 0%. [Effects of the Invention]

[0007] According to the present invention, a polyisocyanurate foam having excellent buckling properties and a predetermined sound absorption performance can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view schematically showing an example of a polyisocyanurate foam. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a cross section of the polyisocyanurate foam shown in FIG. 1 taken along line II-II. [Figure 3] FIG. 2 is a cross-sectional view schematically showing a cross section of the polyisocyanurate foam shown in FIG. 1 taken along line III-III. [Figure 4] Graph showing stress / displacement curves for polyisocyanurate foams according to examples. [Figure 5] Graph showing stress / displacement curves for polyisocyanurate foams according to examples. [Figure 6] Graph showing stress / displacement curves for polyisocyanurate foams according to examples. [Figure 7] Graph showing stress / displacement curves for polyisocyanurate foams according to examples. [Figure 8] Graph showing stress / displacement curves for polyisocyanurate foams according to examples. [Figure 9] 1 is a sound absorption coefficient graph showing the measurement results of normal incident sound absorption coefficient for polyisocyanurate foams according to Examples. [Figure 10] 1 is a sound absorption coefficient graph showing the measurement results of normal incident sound absorption coefficient for polyisocyanurate foams according to Examples. [Figure 11] 1 is a sound absorption coefficient graph showing the measurement results of normal incident sound absorption coefficient for polyisocyanurate foams according to Examples. [Figure 12] 1 is a sound absorption coefficient graph showing the measurement results of normal incident sound absorption coefficient for polyisocyanurate foams according to Examples. [Figure 13] 1 is a sound absorption coefficient graph showing the measurement results of normal incident sound absorption coefficient for polyisocyanurate foams according to Examples. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes the embodiments with reference to the drawings as appropriate. Note that common components throughout the embodiments are designated by the same reference numerals, and redundant explanations will be omitted. The drawings are schematic diagrams for explaining and facilitating understanding of the embodiments, and the shapes, dimensions, ratios, etc. may differ from those of actual devices. However, these can be appropriately modified in design, taking into consideration the following explanation and known techniques.

[0010] The impact absorption and sound absorption performance of polyisocyanurate foams vary depending on various factors, but to achieve both desired impact absorption and sound absorption performance, the polyisocyanurate foam must be made open-celled to a certain extent. As a result, sound waves are more easily propagated within the foam, and vibration energy is more easily converted into thermal energy, thereby improving sound absorption performance. If the degree of open celling is excessive or insufficient, the sound absorption performance of the polyisocyanurate foam will deviate from the sound absorption performance desired by the present invention. Furthermore, to achieve high impact absorption performance, the hardness, density, and open celling of the polyisocyanurate foam, which is a porous elastomer, must be well balanced.

[0011] The polyisocyanurate foam according to the present embodiment is obtained by foaming in a reaction system containing two polyols with different properties and exhibiting a relatively high isocyanate index of 200 to 350. When two polyols with different properties are reacted, the two polyols react randomly with the isocyanate. In this case, a uniform polyisocyanurate foam tends to be less formed than, for example, when a single polyol reacts with the isocyanate. Here, a uniform polyisocyanurate foam refers to a foam with many membranes. As numerous urethane bonds are formed, each of the two polyols acts as a factor that reduces the uniformity of the foam. In other words, when two polyols with different properties are reacted with the isocyanate, a more interconnected polyisocyanurate foam tends to be obtained.

[0012] By setting the isocyanate index in the reaction system within the range of 200 to 350, an excess amount of isocyanate will be present in the system. As a result, compared to when the amount of isocyanate is smaller, the remaining isocyanate will undergo nurate (trimerization) with itself, forming more nurate structures. A nurate structure is a cyclic structure formed by three isocyanate molecules. Therefore, the nurate structure also acts as a factor that reduces uniformity among the countless urethane bonds. As a result, the membrane in the polyisocyanurate foam will be reduced, resulting in the formation of a more interconnected foam.

[0013] Thus, the polyisocyanurate foam according to the embodiment is interconnected to a certain degree even when no separate interconnecting agent is added to the reaction system, and as a result, has a predetermined sound absorption performance. Adding no interconnecting agent to the reaction system is advantageous from the viewpoint of cost, and also has the advantage of facilitating handling of the polyol liquid during the production of the polyisocyanurate foam. Specifically, for example, if an interconnecting agent with poor hydrophilicity is used, it tends to be easily separated from other components, resulting in poor handling. However, it is also possible to add an interconnecting agent to the reaction system according to the embodiment.

[0014] Furthermore, since the isocyanate index in the reaction system is set within the range of 200 to 350, the resulting foam has many nurate structures, as described above. As the number of nurate structures increases, the polyisocyanurate foam becomes harder. A polyisocyanurate foam having a certain hardness in addition to an appropriate degree of interconnection can achieve excellent impact absorption performance, i.e., a high hysteresis loss rate (90% or higher). In other words, the polyisocyanurate foam according to the embodiment exhibits excellent buckling properties. An increase in the number of nurate structures is preferable because it also increases the flame resistance and heat resistance of the polyisocyanurate foam.

[0015] The hysteresis loss rate of the polyisocyanurate foam may be 92% or more, or may be 94% or more. In one example, the hysteresis loss rate is 99.0% or less. Although it cannot be determined solely from the hysteresis loss rate, if the hysteresis loss rate is excessively high, there is a possibility that the predetermined sound absorption performance cannot be achieved. Note that the predetermined sound absorption performance means that the polyisocyanurate foam in question has a normal incidence sound absorption rate of 40% or more over the entire frequency range of 1000 Hz to 3150 Hz in the normal incidence sound absorption rate measurement described below.

[0016] If the isocyanate index in the reaction system is less than 200, the nurate structure will be insufficient, and the hysteresis loss rate may be less than 90%. If the isocyanate index is more than 350, the moldability of the foam will decrease, and the desired sound absorption performance may not be achieved.

[0017] <Method for measuring hysteresis loss rate> The hysteresis loss rate of a polyisocyanurate foam can be measured by the following method.

[0018] First, a measurement sample having dimensions of 50 mm x 50 mm x 50 mm is cut out from the polyisocyanurate foam to be measured. This sample is compressed to a reference thickness position using an 80φ compression tool, where a load of 5 N is applied. The compression is performed along the foam height direction of the polyisocyanurate foam used as the measurement sample. Next, the measurement sample is compressed at a rate of 50 mm / min until the thickness displacement from this reference thickness reaches 70%. The position where the thickness displacement reaches 70% is, in other words, the position where the thickness of the measurement sample in the compressed portion is 30% of the reference thickness.

[0019] After compressing the sample until the thickness displacement reaches 70%, immediately release the pressure from the sample and return the sample to its original position at a speed of 50 mm / min until the thickness displacement from the reference thickness reaches 0%. In other words, the position where the thickness displacement reaches 0% is the position where the thickness of the sample becomes the same as the reference thickness.

[0020] The hysteresis loss rate is calculated according to the following formula 1. (S1-S2) / S1×100 (1) Here, S1 is the sum of stresses when compressing from the reference thickness to the position where the thickness displacement reaches 70%, and S2 is the sum of stresses when returning from the position where the thickness displacement reaches 70% to the reference thickness.

[0021] The polyisocyanurate foam according to the present invention is obtained by foaming a reaction system containing a polyol, a polyisocyanate, a foam stabilizer, a catalyst, and a blowing agent. The reaction system may further contain other additives such as an antioxidant and a plasticizer. The reaction system may consist only of a polyol, a polyisocyanate, a foam stabilizer, a catalyst, and a blowing agent. In this case, for example, the reaction system does not contain a connecting agent, but the connecting effect is achieved for the reasons described above. Furthermore, when the isocyanate index is set within the range of 200 to 350, the foam has many nurate structures, and the hysteresis loss rate of the polyisocyanurate foam can be 90% or more. From the viewpoint of realizing a three-dimensional shape and easily controlling the cell structure, molding, which can produce a three-dimensional shape with concave and convex shapes, is preferred as a production method.

[0022] Each raw material is described below.

[0023] (1) Polyol The polyol (also referred to as the polyol component) contains polyol A having a weight-average molecular weight in the range of 3,000 to 12,000 and an ethylene oxide content of 50% by weight or more, and polyol B having a weight-average molecular weight of 1,000 to 8,000 and an ethylene oxide content of less than 20% by weight. The polyol component may contain a polyol other than polyol A and polyol B. The polyol component may consist of only polyol A and polyol B.

[0024] Polyol A has a weight-average molecular weight in the range of 3,000 to 12,000 and an ethylene oxide content of 50% by weight or more. Since polyol A contains 50% by weight or more of ethylene oxide, it has high polarity and high hydrophilicity. On the other hand, polyol B has a weight-average molecular weight of 1,000 to 8,000 and an ethylene oxide content of less than 20% by weight. Polyol B, which has a low ethylene oxide content, has lower polarity than polyol A and therefore lower hydrophilicity. Polyol A and polyol B have different properties and therefore have low compatibility in the classification of polyols.

[0025] The weight-average molecular weight of polyol A is preferably in the range of 3000 to 9000, more preferably in the range of 7000 to 9000. If the weight-average molecular weight of polyol A is less than 3000, the polyisocyanurate foam will be highly brittle and may be unsuitable for use as a molded product. The ethylene oxide content of polyol A is preferably 60 to 90% by weight, more preferably 65 to 85% by weight. The hydroxyl value of polyol A is, for example, 18 to 52 mgKOH / g. Polyol A is, for example, a polyether polyol.

[0026] The weight ratio of polyol A to the weight of the polyol component is, for example, in the range of 50% by weight to 90% by weight. When this ratio is within this range, good moldability, sound absorption performance, and impact absorption performance can be achieved. A relatively high ratio of polyol A is preferred because the buckling resistance of the resulting polyisocyanurate foam tends to be increased, for example, the stress upon returning after compression tends to be small. The weight ratio of polyol A to the weight of the polyol component is preferably in the range of 65% by weight to 85% by weight, more preferably in the range of 70% by weight to 80% by weight.

[0027] The weight-average molecular weight of polyol B is preferably in the range of 2000 to 8000, more preferably in the range of 2500 to 7000. If the weight-average molecular weight of polyol B exceeds 8000, the hardness may be insufficient and the buckling resistance may be poor. The ethylene oxide content of polyol B may be 0% by weight or more. That is, the ethylene oxide content of polyol B may be 0% by weight or more and less than 20% by weight. Polyol B with a low ethylene oxide content has lower polarity than polyol A and therefore lower hydrophilicity. Polyol A and polyol B have different properties and therefore have low compatibility in the classification of polyols. If the ethylene oxide content of polyol B is 20% by weight or more, the compatibility with polyol A is high, so the degree of interconnection may be insufficient. The hydroxyl value of polyol B is, for example, 20 mgKOH / g to 90 mgKOH / g.

[0028] The weight ratio of polyol B to the weight of the polyol component is, for example, in the range of 10% by weight to 50% by weight. When this ratio is within this range, good moldability, sound absorption performance, and impact absorption performance can be achieved. The weight ratio of polyol B to the weight of the polyol component is preferably in the range of 15% by weight to 35% by weight, more preferably in the range of 20% by weight to 30% by weight.

[0029] The blending ratio of polyol A and polyol B in the polyol component can be determined by appropriately combining the above-mentioned multiple numerical ranges.

[0030] When the polyol component contains other polyols, the proportion of the total weight of polyol A and polyol B in the weight of the polyol component is preferably 80% by weight or more, and more preferably 90% by weight or more.

[0031] (2) Polyisocyanate As the polyisocyanate, it is preferable to use diphenylmethane diisocyanate (MDI: methylenediphenyl diisocyanate). Diphenylmethane diisocyanate may be monomeric MDI, polymeric MDI, or a mixture thereof. The polyisocyanate may contain only one type of MDI, or may contain two or more types. MDI has better curing properties than toluene diisocyanate (TDI: toluene diisocyanate), and is therefore superior in terms of molding.

[0032] (3) Foam stabilizer The type of foam stabilizer is not particularly limited as long as the hysteresis loss rate of the resulting polyisocyanurate foam is 90% or more, but it can be a silicone-based foam stabilizer. In this case, the increased foam stabilization makes it easier to retain the foaming gas generated by the reaction, thereby improving moldability.

[0033] The content of the foam stabilizer in the reaction system is, for example, in the range of 0.5 to 15 parts by weight per 100 parts by weight of the polyol component. If the content of the foam stabilizer in the reaction system is too low, it becomes difficult to retain the foaming gas that is generated, and moldability tends to deteriorate. If the content is too high, the foam stabilization power becomes too high, and sound absorption performance tends to deteriorate. The content of the foam stabilizer in the reaction system is preferably in the range of 1.0 to 3.0 parts by weight per 100 parts by weight of the polyol component.

[0034] (4) Catalyst As the catalyst, a resinification catalyst, an isocyanuration catalyst (trimerization catalyst), a surface modification catalyst, a foaming catalyst, etc. As each catalyst, a known catalyst used for the respective application can be used.

[0035] The resinification catalyst is used in an amount of, for example, 1 to 5 parts by weight relative to the weight of the polyol component. The isocyanuration catalyst is used in an amount of, for example, 1 to 5 parts by weight relative to the weight of the polyol component. The surface modification catalyst is used in an amount of, for example, 0.5 to 3 parts by weight relative to the weight of the polyol component. The foaming catalyst is used in an amount of, for example, 0.1 to 1 part by weight relative to the weight of the polyol component.

[0036] Diethanolamine (DEA) is preferably used as the surface modification catalyst. DEA has OH groups at both ends and a secondary amine in the center. These OH and NH groups crosslink with the NCO groups of the isocyanate, increasing the strength of the skeleton of the resulting polyisocyanurate foam, improving or stabilizing moldability and suppressing skin peeling.

[0037] (5) Foaming agent Any known blowing agent used in the production of general polyisocyanurate foams or polyurethane foams can be used. The blowing agent in the present invention is water. The content of the blowing agent in the reaction system is preferably within the range of 5 to 20 parts by weight per 100 parts by weight of the polyol component. In addition to water, a commonly used auxiliary blowing agent may also be added. Examples of auxiliary blowing agents include chlorofluorocarbons and dichloromethane.

[0038] (6) Other additives Other additives that can be added include, for example, plasticizers and antioxidants. The plasticizer can adjust the hardness and cell structure of the polyisocyanurate foam and improve moldability. The antioxidant can suppress scorch. The other additives are used in an amount of, for example, 3 to 30 parts by weight based on the weight of the polyol component. Any other additives that are commonly used in the production of polyisocyanurate foams or polyurethane foams can be used without limitation.

[0039] The density of polyisocyanurate foam is, for example, 50 kg / m 3 ~100kg / m 3 is within the range.

[0040] The compressive stress of polyisocyanurate foam at 10% deformation is, for example, 0.5 kgf / cm 2 ~4.0kgf / cm 2 is within the range.

[0041] In the present invention, the normal incidence sound absorption coefficient of the polyisocyanurate foam is preferably 40% or more, and more preferably 45% or more, across the entire frequency range of 1000 Hz to 3150 Hz. The normal incidence sound absorption coefficient serves as an index for evaluating sound absorption performance. For example, when the polyisocyanurate foam is used as a lower limb impact absorbing material for an automobile or the like, if the normal incidence sound absorption coefficient is within the above-mentioned range, the passengers of the automobile or the like are less likely to perceive noise in the low frequency range. Therefore, the passengers can enjoy a comfortable ride.

[0042] <Measurement of normal incident sound absorption coefficient> The normal incident sound absorption coefficient of the polyisocyanurate foam is measured by the following method. First, a cylindrical polyisocyanurate foam block having a diameter of 29 mm (29φ) and a thickness of 15 mm is prepared as the object for measuring the sound absorption coefficient. The block can be prepared, for example, using a punching machine equipped with a 29φ punching die. Five such blocks are prepared to calculate the average value of the sound absorption coefficient measurement results.

[0043] The sound absorption coefficient measurement device used is the Rion Co., Ltd. Acoustic Duct Transfer Function Method Normal Incidence Acoustic Measurement System Model 9301, or a device with equivalent functionality. The normal incidence acoustic measurement system applies sound perpendicularly to a sound-absorbing or sound-insulating material inside an acoustic tube (acoustic duct), capturing the reflected or transmitted sound and measuring the material's sound absorption coefficient, acoustic impedance-related items, and transmission loss. Start the normal incidence acoustic measurement system, calibrate the microphone, and complete preparations for sound absorption coefficient measurement.

[0044] The sound absorption coefficient is measured by placing the block at a predetermined position inside the duct so that sound is incident in a direction parallel to the thickness of the block. Sound absorption coefficient measurements are performed in accordance with JIS A 1405:1994. If the block has a decorative surface, the block is placed so that sound is incident on this decorative surface.

[0045] Then, the normal incidence sound absorption coefficients are measured for frequencies of 500 Hz, 630 Hz, 800 Hz, 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, and 6300 Hz. This measurement is performed on each of the five blocks, and the average normal incidence sound absorption coefficient at each frequency is calculated, thereby determining the normal incidence sound absorption coefficient at each frequency. Based on this measurement result, a line graph can be created, with frequency (Hz) on the horizontal axis and sound absorption coefficient (%) on the vertical axis. In this specification, this line graph is referred to as a "sound absorption coefficient graph." The sound absorption coefficient graphs in Figures 8 to 11, which will be described later, are logarithmic graphs.

[0046] In the above measurement, if the sound absorption coefficient is 40% or more at all frequencies of 1000Hz, 1250Hz, 1600Hz, 2000Hz, 2500Hz, and 3150Hz, it can be considered that the normal incident sound absorption coefficient is 40% or more over the entire frequency range of 1000Hz to 3150Hz.

[0047] The shape and dimensions of the polyisocyanurate foam according to the embodiment are not particularly limited. One example of the shape of the polyisocyanurate foam will be described with reference to FIGS.

[0048] Fig. 1 is a plan view schematically showing an example of a polyisocyanurate foam. Fig. 1 illustrates an example in which the polyisocyanurate foam is a lower limb impact absorbing material (foot panel). Fig. 2 is a cross-sectional view schematically showing a cross section of the polyisocyanurate foam shown in Fig. 1 taken along line II-II. Fig. 3 is a cross-sectional view schematically showing a cross section of the polyisocyanurate foam shown in Fig. 1 taken along line III-III.

[0049] The lower leg impact absorbing material 10 comprises a first portion 1, a second portion 2, and a thick portion 3. The first portion 1, the second portion 2, and the thick portion 3 are integrally molded using a single mold to form the lower leg impact absorbing material 10. The lower leg impact absorbing material 10 can be mounted, for example, on the floor of an automobile. A floor mat, for example, is laid on top of the lower leg impact absorbing material 10 mounted on the floor of the automobile, and the occupant's feet are placed on the lower leg impact absorbing material with the floor mat interposed between them.

[0050] The first portion 1 and the second portion 2 are thinner than the thick portion 3. The second portion 2 is roughly rectangular and has end faces defined by boundary portions 4. The first portion 1 and the thick portion 3 extend from the end faces of the second portion 2. The lower limb impact absorbing material 10 is curved so that the boundary portions 4 between the second portion 2 and the first portion 1 and the thick portion 3 form valleys. The boundary portions 4 form valleys on one side of the lower limb impact absorbing material 10, but form peaks on the other side.

[0051] The lower limb impact absorbing material 10 has a surface 5 where the second portion 2, the first portion 1, and the thick portion 3 form a valley. The lower limb impact absorbing material 10 has a back surface 6 where the second portion 2, the first portion 1, and the thick portion 3 form a peak. The thick portion 3 has a convex shape on the surface 5. In other words, the thick portion 3 has a structure where the surface 5 protrudes beyond the surface of the first portion 1, using the surface of the first portion 1 as a reference.

[0052] 1 to 3 illustrate an example in which the polyisocyanurate foam is used as a lower limb impact absorbing material, but the uses of the polyisocyanurate foam are not particularly limited, and it is suitable for uses requiring buckling resistance and sound absorption performance. The polyisocyanurate foam can be used, for example, as a door interior cushioning material, a head protection material, a floor raising material, a tool box, a luggage box, a ceiling material, a seat core material, a sun visor core material, a pillar core material, etc. The foam can be cut to obtain a polyisocyanurate foam of a desired shape.

[0053] [Example] Examples will be described below, but the embodiments are not limited to the examples described below.

[0054] Polyisocyanurate foams according to Examples 1 to 34 were produced by molding according to the formulations shown in Tables 1 and 2 below. In the tables, the blending ratio of each raw material is shown in parts by weight. However, the "isocyanate index" indicates the isocyanate group equivalent (concentration) in the polyisocyanate relative to the total of the active hydroxyl group equivalent (concentration) in the polyol, the hydroxyl group equivalent (concentration) of other materials containing an active hydroxyl group equivalent (concentration), and the hydroxyl group equivalent (concentration) of water.

[0055] Details of the "raw material names" listed in Tables 1 and 2 are as follows:

[0056] (1) QB8000: manufactured by Toho Chemical Industry Co., Ltd. (weight average molecular weight 8000, polyoxyethylene content 80% by weight, hydroxyl value 28) (2) T-3000S: Mitsui Chemicals SKC Polyurethanes Co., Ltd. (weight average molecular weight 3000, polyoxyethylene content 0% by weight, hydroxyl value 56) (3) V8010G: manufactured by Dow Chemical (weight average molecular weight 3000, polyoxyethylene content 9% by weight, hydroxyl value 56) (4) EP-901P: manufactured by Mitsui Chemicals SKC Polyurethanes Co., Ltd. (weight average molecular weight 7000, polyoxyethylene content 15% by weight, hydroxyl value 23) (5) CP1421: manufactured by Dow Chemical (weight average molecular weight 5000, polyoxyethylene content 75% by weight, hydroxyl value 33.5) (6) FA166: manufactured by Sanyo Chemical Industries, Ltd. (weight average molecular weight 6700, polyoxyethylene content 70% by weight, hydroxyl value 25) (7) T-5000D: manufactured by Mitsui Chemicals SKC Polyurethanes Co., Ltd. (weight average molecular weight 5000, polyoxyethylene content 0% by weight, hydroxyl value 33.7) (8) V4701: manufactured by Dow Chemical (weight average molecular weight 5000, polyoxyethylene content 10% to 12% by weight, hydroxyl value 33.7) (9) KC745: manufactured by Sanyo Chemical Industries, Ltd. (weight average molecular weight 5000, polyoxyethylene content 20% by weight to 25% by weight, hydroxyl value 33.7) (10) EP-505S: manufactured by Mitsui Chemicals SKC Polyurethanes Co., Ltd. (weight average molecular weight 3000, polyoxyethylene content 70% by weight to 75% by weight, hydroxyl value 51) (11) JEFFCAT DPA: Manufactured by Huntsman Japan Co., Ltd. Substance name: 1,1'-[[3-(dimethylamino)propyl]imino]bis(2-propanol) Application: Resinization catalyst (12) TMR7: Manufactured by Air Products Japan Co., Ltd. Application: trimerization catalyst (13) DEA: Diethanolamine Use: Surface modification catalyst (14) NE300: Evonik Japan Co., Ltd. Application: Foaming catalyst (15) Niax catalyst A-1: ​​Momentive Performance Materials, Inc. Application: Foaming catalyst (16) B8228: Evonik Japan Co., Ltd. (17) EM ALEX DEG-di-O: Nippon Nyukazai Co., Ltd. Substance name: Diethyl glycol dioleate (18) SF2962: Toray Dow Corning Co., Ltd. (19) VORASURF 1280: Manufactured by Toray Dow Corning Co., Ltd. (20) Irganox 1135: BASF Japan Ltd. Use: Antioxidant (21) Sumijul 44 V 20 L: manufactured by Sumika Covestro Urethane Co., Ltd.

[0057] [Table 1]

[0058] [Table 2]

[0059] (Example 1) A polyol-containing mixture was prepared in a disposable cup by blending raw materials other than polyisocyanate (i.e., polyol component, additives, catalyst, and blowing agent) according to the formulation shown in Table 1 (by hand foaming). The polyol component in Example 1 contained QB8000, which corresponds to polyol A, and T-3000S, which corresponds to polyol B. The resulting polyol-containing mixture was designated as Liquid A. Liquid A was temperature-controlled to 37°C ± 2°C. Polyisocyanate was also prepared as Liquid B, and its temperature was controlled to 37°C ± 2°C.

[0060] A sample production mold with inner dimensions of 350 mm width, 350 mm depth, and 70 mm height was prepared, and the mold was heated to a temperature range of 65°C to 70°C and maintained at that temperature. The temperature was measured using a surface thermometer. The mold consisted of a cylindrical lower mold with a bottom and an upper mold whose top surface was open, and the upper mold could be closed.

[0061] Next, Liquid B was added to Liquid A prepared in a disposable cup, and the mixture was stirred and mixed for 5 seconds to obtain a mixed solution. Here, assuming that the total weight of the polyol components was 100, the weight of Liquid A containing the polyol components was 120.5 parts by weight, and the weight of Liquid B was 77.3 parts by weight. The resulting mixed solution was immediately poured into the lower mold of a mold, and the upper surface of the lower mold was closed using the upper mold, followed by curing for 6 minutes. During this time, the surface temperature of the mold was maintained at 65°C to 70°C. The mixture was then demolded and allowed to stand at room temperature for 2 days to obtain a polyisocyanurate foam measuring 350mm x 350mm x 70mm.

[0062] (Examples 2 to 9) Polyisocyanurate foams were obtained in the same manner as in Example 1, except that the amount of polyisocyanate in the formulation was changed as shown in Table 1, and the isocyanate index was changed as shown in Table 1.

[0063] (Examples 10-20) Polyisocyanurate foams were obtained in the same manner as in Example 1, except that the blending ratio of QB8000 corresponding to polyol A and T-3000S corresponding to polyol B was changed as shown in Table 1.

[0064] (Examples 21-26) Polyisocyanurate foams were obtained in the same manner as in Example 1, except that the types and amounts of polyols used were changed as shown in Table 2.

[0065] (Examples 27-33) Polyisocyanurate foams were obtained in the same manner as in Example 1, except that the types of polyol and foam stabilizer used and the amounts thereof were changed as shown in Table 2.

[0066] (Example 34) A polyisocyanurate foam was obtained in the same manner as in Example 1, except that the formulation of solution A was changed as shown in Table 2 and the isocyanate index was changed to 150.

[0067] <Formability evaluation> The polyisocyanurate foams of each example were evaluated for moldability (cure property) by sensory evaluation. A foam in good condition when demolded was rated "○", a foam with a rough cell structure or underfilling was rated "△", and a polyisocyanurate foam that collapsed or was severely undercured was rated "×". Examples of reasons for an "×" rating include stringiness when demolding was attempted, a foam that was tattered and brittle, or cells inside the foam that collapsed and caved in.

[0068] <Hysteresis loss rate measurement> The hysteresis loss rate (%) of the polyisocyanurate foams according to each example was measured according to the method described in the embodiment. A hysteresis loss rate of 90% or more was marked "○", and a rate of less than 90% was marked "×". However, for those evaluated as "×" in the moldability evaluation, the hysteresis loss rate could not be measured properly, so no measurement was performed. In the "Hysteresis loss rate" row in Tables 1 and 2, examples for which measurement was not performed are indicated by "-".

[0069] <Sound absorption performance evaluation> The sound absorption performance of the polyisocyanurate foams according to each example was evaluated according to the method for measuring the normal incidence sound absorption coefficient described in the embodiments. A normal incidence sound absorption coefficient of 40% or more over the entire frequency range of 1000 Hz to 3150 Hz was evaluated as "○", and a normal incidence sound absorption coefficient of less than 40% over the frequency range of 1000 Hz to 3150 Hz was evaluated as "×". However, for those evaluated as "×" in the moldability evaluation, no evaluation was performed because the sound absorption performance could not be properly evaluated. In the "Sound absorption performance" row of Tables 1 and 2, examples for which no evaluation was performed are indicated by "-".

[0070] <Density measurement> The density of the polyisocyanurate foams according to each example was measured, and all were found to be 60 kg / m 3 The density was evaluated in accordance with the measurement method specified in JIS K 7222:2005.

[0071] As shown in Tables 1 and 2, the polyisocyanurate foams according to Examples 1 to 9, 14 to 22, and 26 to 34 had practical moldability. In other words, the moldability of these examples was evaluated as "good" or "fair," so various evaluations could be carried out.

[0072] 4 to 8 show stress / displacement curves for each example. In the stress / displacement curves shown in Figs. 4 to 8, the horizontal axis represents displacement (%) and the vertical axis represents stress (kgf / cm 2 ) are shown. The hysteresis loss rate was calculated from the obtained stress / displacement curve. Also, Figures 9 to 13 are sound absorption coefficient graphs showing the results of normal incidence sound absorption coefficient measurements for each example. In the sound absorption coefficient graphs, the horizontal axis shows frequency (Hz) and the vertical axis shows sound absorption coefficient (%).

[0073] FIG. 4 shows stress / displacement curves for Examples 1 to 9, each with a different isocyanate index. It can be seen that as the isocyanate index increases, the polyisocyanurate foam tends to become harder due to the increased number of nurate structures. In particular, Examples 4 to 6 exhibited low stress upon return and high impact absorption performance. FIG. 9 also shows a sound absorption graph for Examples 1 to 9. The polyisocyanurate foams of Examples 1 to 6 achieved a sound absorption coefficient of 40% or more across the entire frequency range of 1000 Hz to 3150 Hz. In Examples 1 to 6, the content of nurate structures was appropriate, and therefore the interconnectedness was also appropriate, achieving the sound absorption performance targeted by the present invention. It is believed that Examples 7 to 9 fell outside the desired sound absorption performance range due to the coarse cell structure and excessive interconnection.

[0074] FIG. 5 shows stress / displacement curves for Examples 14 to 20. Examples 14 to 20 show the results when the weight ratio of polyol A to polyol B was gradually changed. Examples with a low ratio of polyol A tended to have a low hysteresis loss rate. Examples 17 to 20, which have a hysteresis loss rate of over 90%, demonstrate excellent impact absorption performance. FIG. 10 shows a sound absorption coefficient graph for Examples 14 to 20. The polyisocyanurate foams of Examples 15 to 18 achieved a sound absorption coefficient of 40% or more over the entire frequency range of 1000 Hz to 3150 Hz. Examples 17 to 18, in which the proportion of polyol A in the polyol component was in the range of 70 to 80 parts by weight, showed excellent sound absorption coefficients even in the low frequency range.

[0075] Fig. 6 shows stress / displacement curves for examples in which the type of polyol used as the polyol component was varied. The polyisocyanurate foams of Examples 4, 21, 22, and 26, which were obtained using reaction systems containing polyol A and polyol B satisfying the specified weight-average molecular weight and ethylene oxide content, exhibited excellent moldability and a hysteresis loss rate of 90% or more. Fig. 11 shows sound absorption coefficient graphs for Examples 21, 22, and 26. Since all of these examples contained polyol A and polyol B satisfying the specified weight-average molecular weight and ethylene oxide content, they achieved a sound absorption coefficient of 40% or more over a wide frequency range, not just in the range of 1000 Hz to 3150 Hz.

[0076] FIG. 7 shows stress / displacement curves for examples in which the type of polyol used as the polyol component was varied. The polyisocyanurate foams of Examples 4, 27, 28, 30, 31, and 33, which were obtained using reaction systems containing polyol A and polyol B satisfying the specified weight-average molecular weight and ethylene oxide content, exhibited excellent moldability and hysteresis loss rates of 90% or more. FIG. 12 shows sound absorption graphs for Examples 4, 27, 28, 30, 31, and 33. Because all of these examples contained polyol A and polyol B satisfying the specified weight-average molecular weight and ethylene oxide content, they achieved sound absorption coefficients of 40% or more over a wide frequency range, not just in the range of 1000 Hz to 3150 Hz.

[0077] FIG. 8 shows a stress / displacement curve for Example 34. FIG. 13 shows a sound absorption coefficient graph for Example 34. For example, the following points can be read from Example 34. That is, even when a polyol component containing polyol A and polyol B satisfying predetermined weight-average molecular weights and ethylene oxide contents is used, if the isocyanate index is low and / or the types and quantities of other components contained in the reaction system are not appropriately controlled, the hysteresis loss rate will be less than 90%. However, as shown in FIG. 13, the polyisocyanurate foam of Example 34 achieved a sound absorption coefficient of 40% or more not only in the range of 1000 Hz to 3150 Hz but also over a wide frequency range.

[0078] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention. [Explanation of symbols]

[0079] 1...first part, 2...second part, 3...thick part, 4...boundary part, 5...surface, 6...back side, 10...lower limb shock absorbing material.

Claims

1. A polyisocyanurate foam obtained by foaming in a reaction system containing a polyol, a polyisocyanate, a foam stabilizer, a catalyst, and a blowing agent, The polyol includes polyol A having a weight average molecular weight in the range of 3,000 to 12,000 and an ethylene oxide content of 50% by weight or more, and polyol B having a weight average molecular weight of 1,000 to 8,000 and an ethylene oxide content of less than 20% by weight, the weight ratio of the polyol A to the weight of the polyol is in the range of 65% by weight to 85% by weight, and the weight ratio of the polyol B to the weight of the polyol is in the range of 15% by weight to 35% by weight; the isocyanate index in the reaction system is 200 or more and 350 or less, The hysteresis loss rate is 90% or more, The hysteresis loss rate is Cutting out a measurement sample having dimensions of 50 mm x 50 mm x 50 mm from the polyisocyanurate foam; Compressing the measurement sample along the foam height direction of the polyisocyanurate foam to a reference thickness at which a load of 5 N is applied using an 80φ compression tool; The measurement sample is compressed along the foam height direction at a speed of 50 mm / min until the thickness displacement from the reference thickness reaches 70%, and then the measurement sample is immediately returned along the foam height direction at a speed of 50 mm / min until the thickness displacement from the reference thickness reaches 0%. Polyisocyanurate foam measured by a method including:

2. 2. The polyisocyanurate foam according to claim 1, wherein the weight average molecular weight of the polyol A is in the range of 3,000 to 9,000.

3. The polyisocyanurate foam according to any one of claims 1 to 2, wherein the foam stabilizer is a silicone-based foam stabilizer.

4. The polyisocyanurate foam according to any one of claims 1 to 3, wherein the blowing agent is water.

5. The polyisocyanurate foam according to any one of claims 1 to 4, wherein the reaction system consists of only the polyol, the polyisocyanate, the foam stabilizer, the blowing agent, and the catalyst.

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