JP5371264B2 - Sheet polyurethane foam - Google Patents

Description

  The present invention relates to a shock-absorbing sheet-like polyurethane foam, and more particularly to a thin sheet-like polyurethane foam useful as a shock-absorbing cushion material used in liquid crystal, plasma, organic EL display portions, hard disk drive gaskets, and the like. is there.

  Thin panels such as liquid crystal, plasma, and organic EL display panels are widely used in various applications such as televisions, personal computers, mobile phones, and car navigation systems. In particular, the demand for displays for mobile phones and small notebook computers is increasing year by year, and both high functionality, thinness, and light weight are required for carrying them. In these thin panels, a gasket is generally disposed as a shock absorbing cushion material on the periphery of a display screen such as a liquid crystal display. As electronic device products have been improved in performance and size in recent years, further improvement in performance has been demanded for gaskets.

An impact-absorbing cushion material that can be used as a gasket is required to be a thin sheet material that is excellent in dustproof property, light-shielding property, impact resistance (impact absorbability), low water absorption (water repellency), and the like. As a conventional gasket, generally, a sliced product obtained by slicing a flexible polyurethane slab foam to a thickness of about 0.5 to 10 mm has been used. However, the slab foam has a low density of usually 20 to 80 kg / m ³ (see, for example, Patent Documents 1 to 3), has a rough cell, and has a self-skin because it is a sliced product. It had the problem that it was inferior to dustproofness and light-shielding property.

In addition, the excellent impact resistance (impact absorbability) required for gaskets is achieved when the resilience to impact is slow (slow recovery), soft (low hardness), and less sag (low compression residual strain). However, it is difficult to provide a polyurethane foam in the form of a thin sheet that satisfies both the slow recovery property, low hardness, and low strain. For example, in order to impart softness, (1) the ratio of isocyanate groups that react with polyol (NCO Index) is decreased, (2) a plasticizer is added to increase the glass transition temperature and bring it closer to the operating temperature of polyurethane. (3) Adding a flexibility-imparting agent. However, since these methods delay or inhibit the urethane curing reaction, a reduction in mechanical properties including compression residual strain is inevitable. On the other hand, it was difficult to impart sufficient softness and slow recovery property while maintaining the mechanical characteristics. In addition, plasticizers and flexibility-imparting agents are often low molecular weight compounds and are not retained in the urethane structure even when added, so they will bleed out to the foam surface over time and contaminate the inside of the display panel and main device. There was a possibility.
JP 2006-282936 A JP 2005-264010 A JP 2006-89582 A

  The present invention has been developed in view of the above-mentioned problems of the background art, and has the softness (low hardness) required as a gasket for thin display panels such as liquid crystals and hard disk drives without deteriorating the compressive residual strain. An object of the present invention is to provide a thin sheet-like impact-absorbing polyurethane foam having a slow recovery property. Another object of the present invention is to provide a thin sheet-like impact-absorbing polyurethane foam having excellent dust resistance and light shielding properties in addition to the above characteristics.

  As a result of diligent research, the present inventors have achieved both a low resilience, low hardness and low strain in a thin sheet-like polyurethane foam having a thickness of 10 mm or less obtained by foam-curing a polyurethane raw material containing a monol and a crosslinking agent. Has been found to be realized, and the present invention has been completed.

That is, according to the present invention, in a sheet-like polyurethane foam obtained by reacting a polyurethane raw material containing a polyol, an isocyanate, a monol and a crosslinking agent, 1 to 7 parts by mass of the monool with respect to 100 parts by mass of the polyol, the crosslinking agent Is a sheet-like polyurethane foam having a density of 150 to 800 kg / m ³ and a thickness of 10 mm or less.

  In one embodiment of the present invention, the monool includes an aliphatic monool having 5 to 16 carbon atoms.

  In another embodiment of the present invention, a compound obtained by adding ethylene oxide and / or propylene oxide to trimethylolpropane is used as the crosslinking agent.

  In another embodiment of the present invention, the polyol includes a dimer acid polyester polyol.

  In another embodiment of the present invention, the sheet-like polyurethane foam has a self-skin layer on at least one side.

According to another aspect of the present invention, a sheet-like polyurethane foam having a density of 150 to 800 kg / m ³ and a thickness of 10 mm or less having a self-skin layer on at least one side is obtained.

According to another aspect of the present invention, a sheet-like polyurethane foam having a density of 150 to 800 kg / m ³ and a thickness of 10 mm or less is obtained in which a synthetic resin film is reactively bonded to at least one surface.

According to the present invention, there is provided a sheet-like polyurethane foam that simultaneously satisfies slow recovery, low hardness, and low strain, which are difficult to achieve in a thin sheet shape having a density of 150 to 800 kg / m ³ and a thickness of 10 mm or less. Thus, in addition to the above characteristics, a sheet-like polyurethane foam excellent in dust resistance and light shielding properties was provided. Therefore, according to the present invention, it has become possible to provide a sheet-like polyurethane foam that is useful as a thin display panel, a hard disk drive gasket, or the like that requires high performance and downsizing.

  The polyol used in the production of the sheet-like polyurethane foam of the present invention is not particularly limited, and polyester polyol, polyether polyol, castor oil and modified products thereof, polybutadiene-based polyol and Various polyols such as a water additive, a polyisoprene-based polyol and a water additive thereof can be used alone or as a mixture of two or more. For example, the polyester polyol includes dimer acid, adipic acid and the like as the acid component, and ethylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 2-methyl-1,3-propanediol, 1,4 as the glycol component. An esterified product obtained by addition polymerization of butanediol or the like can be used. Further, as the polyether polyol, an etherified product obtained by addition polymerization of an oxirane compound such as ethylene oxide, butylene oxide, and tetrahydrofuran using a low molecular weight polyol such as propylene glycol, glycerin, or trimethylolpropane as an initiator can be used.

  In the present invention, it is preferable to use a dimer acid polyester polyol in order to impart low water absorption performance (water repellency). As the dimer acid polyester polyol, an esterified product obtained by addition polymerization of dimer acid and a diol component such as the above-described glycol can be used.

  Next, the isocyanate compound will be described. Isocyanates that can be used in the present invention are not particularly limited, and isocyanate compounds that are commonly used in the art can be used. For example, aromatic or fatty acids having two or more isocyanate groups in one molecule. A cyclic or aliphatic isocyanate compound or a modified product thereof can be used alone or as a mixture of two or more. Specific examples include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI), xylylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI). . It is preferable that the blending ratio of the isocyanate is adjusted so that the isocyanate INDEX ((NCO / OH equivalent ratio) × 100) is 102 to 110.

  In the present invention, monool is further used to impart low hardness and slow recovery to the polyurethane foam. Although it does not specifically limit as monool, A C5-C16 aliphatic monool is used suitably. Specific examples include isononanol (manufactured by Kyowa Hakko Chemical Co., Ltd., trade name Oxocol 900, Mw = 144.3), 1-dodecanol (manufactured by Wako Pure Chemical Industries, Ltd., Mw = 186.34), 1-heptanol (Japanese Kojun Pharmaceutical Co., Ltd., Mw = 116.2), 4-methyl-2-pentanol (manufactured by Wako Pure Chemical Industries, Ltd., Mw = 102.17), 3-methyl-1-butanol (Wako Pure Chemical Industries, Ltd.) And Mw = 88.15).

  The compounding ratio of monool is 1.0 to 7.0 parts by mass, preferably 3.0 to 5.0 parts by mass with respect to 100 parts by mass of polyol. When the blending ratio exceeds 7.0 parts by mass, the compression residual strain tends to deteriorate, which is not preferable. On the other hand, if it is less than 1.0 part by mass, the tendency to reduce hiss is seen, which is not preferable.

  The sheet thickness required for the sheet-like polyurethane foam of the present invention used as a thin impact absorber such as a gasket is 10 mm or less, and is further reduced to 0.1 to 1.0 mm depending on applications. In the production of such a thin sheet-like polyurethane foam, it is difficult to produce a self-heating necessary for foam curing, so that it is usually difficult to produce a foam having little settling (ie, low distortion) and excellent durability. . In particular, in the present invention, since monool is used, the tendency becomes more remarkable. Therefore, in the present invention, a crosslinking agent is used as an essential auxiliary agent for the purpose of promoting the reaction of the polyurethane raw material containing monool, polyol and isocyanate.

  As the crosslinking agent, a compound obtained by adding ethylene oxide and / or propylene oxide to trimethylolpropane is particularly preferably used, and the same compound having a hydroxyl value of OHv = 850 to 1150 is more preferably used. The addition rate of a crosslinking agent is 0.5-3.0 mass parts with respect to 100 mass parts of polyols.

As described above, the polyurethane foam of the present invention is a thin sheet-like foam having a thickness of 10 mm or less obtained by reacting polyol and isocyanate, which are main components, with monool in the presence of a crosslinking agent and foaming and curing. . The production method can be produced by a known method such as a one-shot method or a prepolymer method. Unlike a conventional slab foam cut product, the sheet-like foam of the present invention has a high density and has a self-skin on at least one side, and thus has excellent dust resistance and light shielding properties. The density of the sheet-like polyurethane foam of the present invention is preferably 150 to 800 kg / m ³ . When the density is less than 150 kg / m ³ , the dustproof property and the light shielding property are not sufficient. On the other hand, when the density exceeds 800 kg / m ³ , the hardness becomes high and is not suitable as the shock absorbing cushion material used in the present invention.

  Moreover, the sheet-like polyurethane foam of this invention can take the form integrated with the synthetic resin film by carrying out the reaction adhesion of the synthetic resin film to at least one surface. When the film is reacted and bonded, the sheet-like polyurethane foam of the present invention is subjected to secondary processing and used as a display part or HDD gasket, so that an elongation preventing effect is exhibited and dimensional stability is improved, which is preferable.

  A synthetic resin film having a melting point of 150 ° C. or higher is preferably used. For example, PET, PBT, amide, nylon and the like are used, but PET and PBT are preferable. Moreover, in order to make these PET and PBT react and adhere more strongly to the polyurethane foam, those obtained by subjecting the reaction adhesion surface to chemical treatment such as corona discharge treatment, polyurethane resin or acrylic resin are preferably used.

In the present invention, auxiliary agents such as a foam stabilizer, a foaming agent, a catalyst, and a flame retardant are used as necessary.
As the foam stabilizer, silicone foam stabilizers and surfactants known in the art can be used. As the silicone foam stabilizer, one containing a reactive group that reacts with isocyanate is preferably used because it is incorporated into a urethane resin and suppresses bleat out and becomes a low water-absorbing polyurethane foam. Specifically, a silicone foam stabilizer containing a reactive group such as OH group, NH group, NH ₂ group, SH group, COOH group, CH ₂ OH group and the like is particularly preferable. Examples of the surfactant include diethylamino oleate, sorbitan monostearate, glycerin monooleate, vinyl pyrrolidone and the like.

  Examples of the blowing agent include water, an inert gas that is a gas at normal pressure (eg, nitrogen, carbon dioxide, air, etc.), a halogenated alkane (eg, monofluorinated trichloromethane, dichloromethane, etc.), or a low boiling point alkane (eg, , Butane, pentane, etc.), azobisisobutyl that generates cracked nitrogen gas, etc., and tolyl can be used in the art.

  As the catalyst, tin-based, titanium-based, bismuth-based, nickel-based organometallic catalysts, monoamines, diamines, triamines, cyclic amines, alcohol amines, ether amine-based amine catalysts, etc. Known catalysts can be used.

  As flame retardants, brominated flame retardants, chlorinated flame retardants, antimony oxide flame retardants, red phosphorus flame retardants, metal hydrates (metals: Al, Fe, Zn, Ca, Ba, Ni, etc.), thermal expansion Uses known flame retardants such as graphite, nitrogen compounds (eg, melamine, melamine cyanurate, etc.), phosphate flame retardants (eg, halogen-containing phosphate esters, phosphazene compounds, phosphate esters, polyphosphates, etc.) can do.

  EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. In the following, “part” means part by mass.

[Manufacture of specimens]
(1) Examples 1 to 6, 8, Comparative Examples 1 to 2 , Reference Example 1 (Isononanol (carbon number 9; melting point: −30 ° C. or lower))
Example 1
1. IR-94 (manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) with 100 parts of dimer acid ester, 1.0 part of isononanol (manufactured by Kyowa Hakko Chemical Co., Ltd.) as monool, and EO added to trimethylolpropane as a crosslinking agent. 0 parts, 0.35 parts of amine catalyst, 2.0 parts of pigment, 0.05 part of reactive silicone foam stabilizer having an OH group that reacts with isocyanate, 0.15 part of water and 20 parts of flame retardant are sufficient in a laboratory mixer Then, Cosmonate M200 (manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) (NCO = 31.4%) is added as an isocyanate component so that the NCO / OH ratio is 1.05, and further mixed. The resulting mixture is uniformly applied to the process paper release surface of the PET film that has been subjected to the release treatment using an application bar, and the process paper is then applied to the upper surface so that the release treatment surface is also on the heating oven (80 ° C. The polyurethane foam sheet (Example 1) which has a self-skin on both surfaces was hardened | cured by * 3 minutes +100 degreeC * 3 minutes). This foam sheet material was heated as a secondary cure in a heating oven at 70 to 120 ° C. for 6 to 22 hours to complete the urethane curing reaction.

Examples 2-6 , 8, Comparative Examples 1-2 , Reference Example 1
Each polyurethane foam (Examples 2-6 , 8, Comparative Examples 1-2 , Reference Example 1 ) was obtained in the same manner as in Example 1 except that the addition amount of isononanol was changed as shown in Table 1. .

In addition, the performance evaluation mentioned later measured with the test piece which aged the obtained foam sheet for 3 days at normal temperature.

(2) Examples 9 to 14 and Comparative Example 3 (1-dodecanol (carbon number 12; melting point 21 to 25 ° C.))
For Example 1, as monool, instead of isononanol, 1-dodecanol (manufactured by Wako Pure Chemical Industries, Ltd.) was used at the compounding ratio shown in Table 2-2 below, and the same as in Example 1 Test pieces (Examples 9 to 14 and Comparative Example 3) were produced under the conditions.

(3) Examples 15 to 20 and Comparative Example 4 (1-heptanol (carbon number 7; melting point −34 ° C.))
For Example 1, as monool, instead of isononanol, 1-heptanol (manufactured by Wako Pure Chemical Industries, Ltd.) was used in the same manner as in Example 1 except that it was used at the compounding ratio shown in Table 2-3 below. Test pieces (Examples 15 to 20, Comparative Example 4) were produced under the conditions.

(4) Examples 21 to 26, Comparative Example 5 (4-methyl-2-pentanol (carbon number 6; melting point −90 ° C.))
For Example 1, except that isononanol was used instead of isononanol and 4-methyl-2-pentanol (manufactured by Wako Pure Chemical Industries, Ltd.) was used at the blending ratio shown in Table 2-4 below. Test pieces (Examples 24 to 30) were prepared under the same conditions as in Example 1.

(5) Examples 27 to 32, Comparative Example 6 (3-methyl-1-butanol (5 carbon atoms; melting point: 117.2 ° C.))
For Example 1, except that isononanol was used instead of isononanol, and 3-methyl-1-butanol (manufactured by Wako Pure Chemical Industries, Ltd.) was used at the compounding ratio shown in Table 2-5 below. Test pieces (Examples 27 to 32, Comparative Example 6) were produced under the same conditions as in Example 1.

(6) Examples 33 to 36, Comparative Examples 7 to 10
Test pieces (Examples 33 to 36, Comparative Examples 7 to 10) were produced under the same conditions as in Example 1 except that the blending ratio of isononanol and the crosslinking agent was changed.

[Evaluation of performance, etc.]
The performance and characteristics of the obtained test piece were evaluated as follows.
-Foam density The volume and mass were measured by the method based on JIS K6400 using the test piece of length 100x width 100mm, and the foam density was computed. (Number of samples: n = 2))
-Sheet thickness The sheet thickness was measured according to JIS K6400. The test piece was punched out 100 × 100 mm in width, 9 points were measured with a dial gauge having an accuracy of 1/100 mm in the foaming direction, and the average value was taken as the sheet thickness.

-Hysteresis loss The hysteresis loss was measured according to JIS K6400. A test piece (length 30 mm x width 30 mm (n = 2)) in the center of a universal material testing machine (UCT-500 manufactured by ORIENTEC Co., Ltd.) that has an automatic recording device and can keep the compression speed constant. It was compressed so that the thickness was compressed by 25% at a compression speed of 50 mm / min. This behavior was recorded on chart paper using an automatic recording device, and the hysteresis loss was measured by the following equation from the behavior change at the time of compression and release.

Hysteresis loss (%) = {B / (A + B)} × 100
In formula, A and B represent each area in the compression hardness-compression ratio curve shown by FIG.

-25% compression residual strain The compression residual strain was measured by the method based on JISK6400 using the test piece of length 30mm x width 30mm. Using two flat metal plates for compression that do not easily deform, compress and fix in parallel to 25% of the thickness of the test piece, and hold it in an oven at a temperature of 70 ° C. for 22 hours. The thickness after taking out from 30 minutes and leaving it to stand at room temperature for 30 minutes was measured. The compressive residual strain was calculated from the following equation.

Compression residual strain (%) = {(Thickness before test−Thickness after test) / Thickness before test} × 100
・ 25% compression hardness A test piece is placed in the center of a universal material testing machine (UCT-500 manufactured by ORIENTEC Co., Ltd.) that has an automatic recording device and can keep the compression speed constant. Compressed and measured until the thickness was compressed by 25% in minutes. The test piece was used by laminating 30 mm length × 30 mm width to about 10 mm (n = 2).

-Water absorption rate A test piece (length 50 mm x width 50 mm, n = 2) was immersed for 24 hours under a water pressure of 100 mmAq, a change in mass of the test piece was measured, and a water absorption rate was calculated from the following equation. The mass (g) of water absorption was converted as 1 g = 1 cm ³ .

Water absorption rate (Vol%) = {(mass after water absorption (g) −mass before water absorption (g)) / volume of test piece (cm ³ )} × 100
The evaluation results are shown in Tables 2-1 to 2-6.

FIG. 1 shows an example of a compression hardness-compression rate curve based on JIS K6400.

Claims (3)

In a sheet-like polyurethane foam obtained by reacting a polyurethane raw material containing a dimer acid polyester polyol , an isocyanate, an aliphatic monool having 5 to 16 carbon atoms, and a compound obtained by adding ethylene oxide and / or propylene oxide to trimethylolpropane as a crosslinking agent the monol 1-7 parts by weight with respect to the polyol 100 parts by weight, the crosslinking agent is 0.5 to 3 parts by weight, a density 220 ~800kg / ^{m 3,} a thickness of 10mm or less of the sheet-like gasket High density polyurethane foam. The sheet-like high - density polyurethane foam for gaskets according to claim 1, which has a self-skin layer on at least one side. The sheet-like high - density polyurethane foam for gasket according to claim 1 or 2 , wherein a synthetic resin film is reactively bonded to at least one surface.

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