JP2007277390A - Curable composition which is cured to give low hardness urethane elastomer gel material and low hardness urethane elastomer gel material obtained by curing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low hardness urethane elastomer gel material which has a high impact-absorbing property, a low staining property, and excellent heat resistance, little affects environments, and has flame retardancy, especially flame retardancy compatible with 94V-0 standard regulated in UL-94, and to provide a composition which is cured to give the low hardness urethane elastomer gel material. <P>SOLUTION: (I) This curable composition which is cured to give the low hardness urethane elastomer gel material comprises (A) a compound derived from a hydroxy group-containing higher fatty acid and having 1.9 to 2.0 hydroxy groups per molecule on the average, (B) an isocyanate compound having 2.0 to 3.0 isocyanate groups on the average or its diol derivative, and (C) a higher fatty acid triglyceride whose intramolecular hydroxy groups are modified, or (II) the curable composition which is the same as the composition (I) except that the component (A) has 1.7 to less than 1.9 hydroxy groups on the average and the component (C) is substantially not contained. The urethane elastomer gel material obtained by curing (I) or (II). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a curable composition derived from a hydroxyl group-containing higher fatty acid and cured to give a low-hardness urethane elastomer gel material. The present invention also relates to a low-hardness polyurethane elastomer gel material obtained by curing it. In particular, the present invention is cured, does not contain a halogen-based or phosphorus-based flame retardant, has flame retardancy according to UL94 flame retardancy standard of 94V-0, and has shock absorption, heat resistance and adhesiveness. The present invention relates to a curable composition that provides a low-hardness urethane elastomer / gel material, and a low-hardness polyurethane elastomer / gel material obtained by curing the composition.

  In recent years, HDDs that store large volumes of data have been increasingly used for mobile products, with the drawback of being easily broken when subjected to an impact. For the purpose of absorbing the impact and protecting the HDD, it is considered to apply an elastomer gel material having a low hardness and shock absorption to the HDD, particularly a portion that is easily damaged by the impact. Yes. Such low-hardness elastomers are required to have low pollution, flame retardancy, and various properties that meet environmental considerations in addition to the above-described impact absorption. In particular, electronics-related products are required to conform to flame retardant standards such as UL-94. Therefore, if a plasticizer is used to obtain flexibility, there is a dilemma that such flame retardant properties cannot be obtained. is there.

  In order to make such a low-hardness elastomer flame-retardant, a halogen-based flame retardant (Patent Literature 1) or a red phosphorus flame retardant (Patent Literature 2) is blended. However, halogen-based and phosphorus-based flame retardants cause environmental pollution and circuit failure, and many of these are liquids. Flame retardants can cause bloom and bleed and foul surrounding parts. Many of the phosphate ester flame retardants having a halogen atom in the molecule suppress the urethanization reaction to lower the productivity, and promote the deterioration of the low-hardness elastomer / gel material.

  On the other hand, blending a metal hydroxide such as aluminum hydroxide (Patent Documents 3 and 4) as a flame retardant has also been proposed. However, the metal hydroxide is solid, and in order to satisfy the required flame retardance, a large amount of metal hydroxide needs to be blended, so that the hardness of the elastomer is increased. Therefore, it is not possible to obtain a low-hardness elastomer gel material having satisfactory flame retardancy.

  Therefore, an elastomer gel material having low hardness, impact absorption, no contamination, and necessary flame retardancy has not been obtained.

JP 2000-143994 A JP 2000-204266 A JP 58-138724 A JP-A-2005-171102

  The object of the present invention is high impact absorption, low contamination, excellent heat resistance, little impact on the environment, and flame retardancy, especially conforms to the 94V-0 standard defined in UL-94 It is an object of the present invention to provide a low-hardness elastomer gel material having flame retardancy, and a composition that cures to give such a low-hardness elastomer gel material.

  As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors have obtained a diol derived from a hydroxyl group-containing higher fatty acid such as castor oil fatty acid and having two hydroxyl groups per molecule per molecule. A low-hardness elastomer gel material obtained by reacting with an isocyanate compound having an average of 2.0 to 3.0 isocyanato groups or a diol derivative thereof uses a higher fatty acid glyceride as a plasticizer. The inventors have found that the present invention has various characteristics and have completed the present invention.

That is, the present invention
(A) a hydroxyl group-containing compound derived from a higher fatty acid containing one hydroxyl group and having 1.9 to 2.0 hydroxyl groups per molecule and having a number average molecular weight of 600 or more;
(B) an isocyanate compound having an average of 2.0 to 3.0 isocyanato groups per molecule or a diol derivative thereof;
(C) a higher fatty acid glyceride, wherein the hydroxyl group remaining in the glycerin moiety and the hydroxyl group of the higher fatty acid in which the higher fatty acid has a hydroxyl group in the carbon chain are modified to be cured and have a low hardness urethane elastomer / gel material It relates to a curable composition which gives
The present invention also provides
(A) a hydroxyl group-containing compound which is derived from a higher fatty acid containing one hydroxyl group and has 1.7 or more and less than 1.9 hydroxyl groups per molecule and a number average molecular weight of 600 or more; ) Isocyanate compounds having an average of 2.0 to 3.0 isocyanato groups per molecule or diol derivatives thereof;
It is related with the curable composition which hardens | cures and gives a low-hardness urethane elastomer gel material which does not contain said (C) substantially.
The present invention further relates to a low-hardness polyurethane elastomer gel material obtained by curing any of the above compositions.

  The low-hardness urethane elastomer gel material obtained by the present invention uses (A) a diol derived from a hydroxyl group-containing higher fatty acid as the diol, thereby providing high impact absorption, low bleeding, excellent heat resistance and hot water resistance. Has little impact on the environment. Moreover, by using monool together or by using (C) a higher fatty acid glyceride that does not contain a hydroxyl group in the carbon chain as a plasticizer, the polyurethane obtained by curing has a low crosslink density, and is halogen-based or phosphorus-based. Excellent flame retardancy can be obtained without using a flame retardant.

  The component (A) used in the present invention is a hydroxyl group-containing compound having a diol compound derived from a higher fatty acid containing one hydroxyl group as a main component and having 1.7 to 2.0 hydroxyl groups per molecule. is there. Among the components (A), the compound having two hydroxyl groups per molecule is, for example, a hydroxyl group-containing higher fatty acid obtained from a higher fatty acid glyceride containing one corresponding hydroxyl group or two lower alkyl esters thereof as glycols. Or obtained by diesterification with a polymeric diol such as polyether diol or polyester diol, or by a transesterification reaction of the glyceride, and in the higher fatty acid moieties present at both ends of the molecule, the molecule of component (A) Contains a total of two hydroxyl groups. Examples of the above-mentioned hydroxyl-containing higher fatty acid include hydroxycapric acid, hydroxylauric acid, hydroxymyristic acid, hydroxyhexadecenoic acid, hydroxystearic acid, ricinoleic acid, hydroxybehenic acid, hydroxylignoceric acid, and the like. As long as these hydroxyl groups do not depart from the above range, higher fatty acids containing a plurality of hydroxyl groups, such as dihydroxy stearic acid, dihydroxy arachidic acid and trihydroxy stearic acid, may be used. It is derived from natural fats and oils containing hydroxyl group-containing higher fatty acid glycerides such as ricinoleic acid and 12-hydroxystearic acid, such as castor oil and hydrogenated castor oil, and hydrogenated products thereof. You may use the acid mixture which contains the fatty acid which does not contain such a hydroxyl group as an impurity as it is. An epoxidized fatty acid obtained by hydrolyzing an epoxidized unsaturated oil such as epoxidized soybean oil, epoxidized linseed oil, or epoxidized castor oil may be opened and used as a hydroxycarboxylic acid.

  In order to lower the crosslinking density and lower the hardness of the elastomer gel by lowering the average number of hydroxyl groups of component (A), that is, functionality, as part of component (A), stearic acid, oleic acid, linoleic acid By using a higher fatty acid containing no hydroxyl group as a part of the raw material, a hydroxyl group-containing compound having a hydroxyl group only in one higher fatty acid portion may be mixed as a part of the component (A) molecule. In this case, since there exists a part which does not contain a hydroxyl group as the higher fatty acid part of the component (A), the hydroxyl group-containing compound contains a small amount of monool. As the higher fatty acid moiety, ricinoleic acid, castor oil fatty acid or hydrogenated fatty acid thereof is particularly preferred because it can be easily obtained and can form an elastomer gel having excellent physical properties.

  As another method for lowering the average number of hydroxyl groups in component (A), the above-mentioned hydroxyl group-containing higher fatty acid such as ricinoleic acid or hydroxystearic acid; or a naturally occurring higher fatty acid mixture containing them, such as castor oil fatty acid or hydrogenated A castor oil aliphatic ester may be esterified with a monohydric alcohol and used in combination with the above-mentioned diol compound as a monool compound. Examples of the monool compound include methyl ester, ethyl ester and isopropyl ester of the above hydroxyl group-containing higher fatty acid.

  Examples of raw material diols connecting the above two higher fatty acid moieties include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 2-methyl- Glycols such as 1,5-pentanediol, 1,6-hexanediol, hydrogenated dimer diol; ether glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol; polyethylene glycol Polyether diols such as polypropylene glycol and oxyethylene / oxyethylene copolymer glycol; such as polycaprolactone diol and copolymer diol of adipic acid and 1,4-butanediol Li ester diols; polybisphenol A carbonate diol, poly (1,4-butylene) diol, polycarbonate diols such as poly (1,6-hexylene) carbonate diol; polybutadiene diol are exemplified.

  The number of hydroxyl groups in component (A) is an average of 1.7 to 2.0 per molecule as described above. If it is less than 1.7, it cannot be cured to form an elastomer gel material. Moreover, when it exceeds 2.0, the obtained hardened | cured material will not only become hard but satisfactory flame retardance will not be obtained.

  When the number of hydroxyl groups per molecule of the component (A) is in the range of 1.9 to 2.0, by blending the component (C) described later as a plasticizer, it is flexible, heat resistant and flame retardant. An excellent gel is obtained. On the other hand, when the number of hydroxyl groups is 1.7 or more and less than 1.9, the degree of crosslinking of the cured product is lowered by lowering the number of hydroxyl groups in this way. Since the component (C) lowers the flame retardancy, the composition contains substantially no component (C) in order to obtain satisfactory flame retardancy.

  (A) The number average molecular weight of a component is 600 or more, Preferably it is 800-3,000. When the number average molecular weight is less than 600, the crosslinking density becomes high, and a gel-like polyurethane having low hardness cannot be obtained.

  (B) component used for this invention reacts with (A) component, and forms a polyurethane. Isocyanate compounds include p- or m-phenylene diisocyanate, 2,4- or 2,6-toluene diisocyanate, a mixture of both, m-xylene diisocyanate, p-xylene diisocyanate, tetramethyl m-xylene diisocyanate, 1,5- Aromatic diisocyanates such as naphthalene diisocyanate, 4,4′- or 2,4′-diphenylmethane diisocyanate, mixtures of both, polycondensates (polymeric MDI); and tetramethylene diisocyanate, hexamethylene diisocyanate, 2,2,4- Or aliphatic such as 2,4,4-trimethylhexamethylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate Isocyanates are exemplified, (A) as component of the hydroxyl groups react even secondary progresses more reactive diphenylmethane-4,4'-diisocyanate are preferred. An oligomer such as isocyanurate body, allophanate body, biuret body and the like mixed in the synthesis of these isocyanate compounds may be present in a slight amount, but in order to impart flame retardancy to the resulting polyurethane, (B ) The content of these oligomers is constrained to have an average of 2.0 to 3.0, preferably an average of 2.0 to 2.5, isocyanato groups or groups derived therefrom per component molecule. Further, these isocyanate compounds may be used in the form of a diol derivative obtained by reacting with a diol such as polypropylene glycol.

  The blending amount of the component (B) is such that the unreacted isocyanato group remains and does not hinder the polymerization, and the unreacted component (A) does not bleed out from the obtained gel material. The molar ratio of the isocyanate group of the component to the hydroxyl group of (A), that is, the range where the isocyanate index is from 0.85 to 1.20 is preferred, and the range from 0.95 to 1.10.

  The component (C) used in the present invention is a plasticizer for making the polyurethane formed by reacting the components (A) and (B) more flexible. As the component (C), a glyceride of a higher fatty acid, preferably a triglyceride, is used, and the hydroxyl group remaining in the glycerin moiety is modified in advance so that the component (C) itself does not react with the component (B). Used. When a hydroxyl group is present in the higher fatty acid moiety, the hydroxyl group is similarly modified. Examples of higher fatty acids include saturated fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid; unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid; Higher fatty acids are exemplified. As glycerides, natural fats and oils containing such higher fatty acids, such as olive oil, cottonseed oil, soybean oil, peanut oil, rapeseed oil and the like may be used.

  In order to prevent bleeding out of the component (C), a higher fatty acid glyceride modified with a hydroxyl group of the hydroxyl group-containing higher fatty acid is preferred from the viewpoint of compatibility with the component (A), and the same hydroxyl group-containing higher glyceride as the higher fatty acid part of the component (A). Triglycerides in which the hydroxyl group of the fatty acid is modified are more preferred. Examples of such higher fatty acids include ricinoleic acid and hydroxystearic acid, and are derived from natural fats and oils containing hydroxyl group-containing higher fatty acid glycerides as the main components, such as castor oil and hydrogenated castor oil, and stearin. You may use the acid mixture which contains the fatty acid which does not contain a hydroxyl group like an acid, linoleic acid, and oleic acid as an impurity.

  The modification of the hydroxyl group includes methods such as acetylation, benzyl etherification, and t-butyldimethylsilylation. The modifying agent is inexpensive and readily available, and easy to handle, regardless of the position of the secondary hydroxyl group. Acetylation is preferred because it is easily modified and not demodified under normal conditions. The component (C) preferably has a number average molecular weight of 800 or more because it does not bleed out from the resulting gel and does not adversely affect its flame retardancy. In total, the component (C) is most preferably acetylated ricinoleic acid triglyceride.

  The blending amount of the component (C) is preferably 45% by weight or less based on the total amount of (A), (B), and (C) because it does not bleed out from the gel material obtained by crosslinking. In addition, as above-mentioned, when the hydroxyl group per molecule of the (A) component to be used is less than 1.9, (C) component is not mix | blended substantially. Here, the fact that the component (C) is not substantially blended means that even if the component (C) is present, the amount thereof is less than 1% by weight with respect to the total amount of (A) and (B). means.

  In order to accelerate the reaction between the component (A) and the component (B), a catalyst can be blended in the composition of the present invention. Such catalysts include triethylamine, triethylenediamine, 2-methyltriethylenediamine, N, N, N′N′-tetramethylethylenediamine, N, N, N′N′-tetramethyltetramethylenediamine, N, N, N′N′-tetramethylhexamethylenediamine, bis (2-ethylaminoethyl) ether, N, N, N′-trimethylaminoethylethanolamine, N, N-dimethylcyclohexylamine, 1,4-diaza [2. 2.2] bicyclooctane, 1,8-diazabicyclo [5.4.0] undecene-7, N-methylmorpholine, N-ethylmorpholine, N, N-dimethylaminoethylmorpholine, 1-isobutyl-2-methylimidazole , Amines such as 1- (2-hydroxypropyl) imidazole; These partial ammonium salts; metal organic acid salts such as tin octoate, tin naphthenate, tin oleate, zinc octoate, zinc naphthenate; dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dibutyltin Examples include organotin compounds such as thiocarboxylate; metal chelate compounds such as acetylacetonatoiron. These catalysts may be used alone or in combination of two or more. When an elastomer gel having a low hardness is used as in the present invention, 1,8-diazabicyclo [5.4. 0] It is preferable to use one or more selected from undecene-7, organotin compounds and acetylacetonatoiron. The amount of catalyst used varies depending on the type of catalyst and is selected so as to complete the urethanization reaction under desired conditions.

  In addition to the components (A) and (B), and the component (C) and a catalyst used as necessary, the composition of the present invention includes a filler, an antifoaming agent, a dehydrating agent, an ultraviolet ray as necessary. Various additives such as an absorber, a light stabilizer, and an antioxidant can be blended.

  The curable composition of the present invention is usually prepared by mixing the component (B) in a premix containing the component (A) and the component (C) as necessary, and further mixing other components as necessary. can do. (B) Reaction progresses with the mixing | blending of a component, and a gel is formed.

  Preparation of the composition is accomplished by mixing uniformly by mixing means such as a stirrer, mixer, mixing head of urethane injector.

  The composition thus prepared is molded by a method such as casting, injection molding, transfer molding or compression molding, and is usually cured by heating to 60 to 110 ° C. to produce a low-hardness polyurethane elastomer gel. be able to. Polyurethane elastomer gel is required to have excellent impact absorbability in applications that protect light parts such as HDDs, and the hardness according to Asker CsC2 hardness meter is 1 or more, and the hardness according to JIS K7312 is According to a type C hardness tester (hereinafter simply referred to as “type C hardness”), it is preferably 40 or less, and generally in the range of type C hardness 1 to 30 is more preferable, but for shock absorption type C hardness A range of 1 to 20 is particularly preferred. On the other hand, in applications such as spacers, the optimum range varies depending on the application, such as the range of type C hardness 20 to 40 is particularly preferred from the viewpoint of workability.

  Hereinafter, the present invention will be described in more detail by way of examples. In these examples, unless otherwise specified, parts are parts by weight. However, the compounding quantity of (B) component is shown by the isocyanate index, ie, the number of isocyanate groups of (B) component with respect to the number of hydroxyl groups in (A) component. The present invention is not limited by these examples.

In the examples and comparative examples, the following components (A), (B), (C), their contrast materials and catalysts were used.
A-1: Castor oil-based polyester polyol (bifunctional, number average molecular weight 2,500, hydroxyl value 45);
A-2: Castor oil fatty acid methyl ester (monofunctional, number average molecular weight 350, hydroxyl value 164);
A-3: Polypropylene glycol (bifunctional, number average molecular weight 2,500, hydroxyl value 45);
A-4: Glycerin ester mixture of ricinoleic acid (trifunctional, number average molecular weight 900, hydroxyl value 95);
B-1: isocyanato group-containing part derived from diphenylmethane-4,4′-diisocyanate at the molecular end and a prepolymer having a polyoxypropylene chain (average functional group number 2.3, NCO 23%);
B-2: Polymeric MDI (average functional group number 2.9, NCO 29.6%)
C-1: acetylated ricinoleic acid triglyceride (molecular weight 1,000);
C-2: Olive oil;
C-3: soybean oil;
C-4: peanut oil;
C-5: bis (2-ethylhexyl) phthalate;
C-6: diisononyl phthalate;
C-7: acetylated butyl ricinoleate;
C-8: Tris-trimellitic acid tris (2-ethylhexyl);
T-1: Dibutyltin dilaurate

Preparation of composition and preparation of sample Premix was prepared by mix | blending (A) component, (C) component, and a catalyst with the mixture ratio of a composition table | surface, and mixing using a stirrer. (B) component was mix | blended with this and it mixed until it became uniform, and obtained the composition sample. After defoaming with a vacuum pump, sandwiched in a polyethylene terephthalate film with peelability, put into a 70 ° C hot air heating furnace and heated for 60 minutes to crosslink, and test the thickness according to the evaluation method A piece was made.

Evaluation method Surface hardness:
A sample having a thickness of 5 mm was measured for hardness by a type C hardness tester according to JIS K7312. Moreover, about the soft sample which cannot obtain an exact measured value with a type C hardness tester, hardness was measured with the CsC2 type hardness meter by an Asker company.
Non-contaminating:
The sample having a thickness of 5 mm was evaluated for the presence or absence of bleeding according to JIS K6267. That is, the sample was sandwiched between medicine wrapping papers and left in a constant temperature bath at 70 ° C. for 24 hours while applying a load of 7 pKa using a weight. The surface of the drug-wrapping paper in contact with the sample was observed for the presence or absence of bleeding from the sample, and evaluated as follows.
○: No bleed (medicine wrapping paper is not wet)
×: Bleed (medicine wrapping paper is wet)
Heat-resistant:
A sample having a size of 50 × 50 mm and a thickness of 1 mm was left in a constant temperature bath at 80 ° C. for 24 hours, and the appearance of the test piece was observed and evaluated as follows.
○: No deformation and melting ×: Flame resistance with deformation and / or melting Flame resistance of a sample having a thickness of 1 mm was evaluated by the UL-94 V-0 test method.

Examples 1 and 2 and Comparative Examples 1 to 4
Examples 1, 2 and Comparative Example 1 using A-1 which is a castor oil-modified diol corresponding to the component (A) of the present invention, and Comparative Examples 2 to 4 using A-3 which is a polyether diol. Compared. The experimental results are shown in Table 1. In addition, Comparative Examples 1 and 2 are examples in which the component (C) was not blended as a plasticizer, and the others were examples in which C-1 corresponding to the component (C) of the present invention was blended.

Comparative Examples 5-8
The compositions of Comparative Examples 5 to 8 were prepared using the bifunctional A-1 and the trifunctional A-4 in combination, and the same evaluation was performed. Table 2 shows the composition, the average number of functional groups of the hydroxyl group-containing compound, and the experimental results.

Examples 3-5, Comparative Examples 9-12
Experiments of Examples 3 to 5 in which A-1 and vegetable oil are combined, and Comparative Examples 9 to 12 in which A-1 is combined with C-3 to 8 which is a plasticizer not belonging to the component (C) of the present invention. The results are shown in Table 3.

Example 6, Comparative Examples 13-15
Bifunctional A-1 and monofunctional A-2 were used in combination as component (A), and the compositions of Example 6 and Comparative Examples 13 to 15 were prepared and evaluated in the same manner. Table 4 shows the composition, the average number of functional groups of component (A), and the experimental results.

  The bifunctional A-1 is used as the component (A), B-1 and B-2 are used in combination as the component (B), or B-2 is used alone, and the average functional group number of the component (B) is 2. The same experiment was conducted at 5 to 2.9. Table 5 shows the composition, the average number of functional groups of the component (B), and the experimental results.

  As shown in Tables 1, 3 and 5, the polyurethane elastomer gels obtained from the compositions of Examples 1 to 3 using the components (A), (B) and (C) of the present invention were excellent. It exhibited flexibility, non-contamination and heat resistance, and also exhibited flame retardancy satisfying V-0 according to UL-94. Further, as shown in Table 4, when the average functional group number is 1.8 using a bifunctional and monofunctional hydroxyl group-containing compound as the component (A), an excellent polyurethane elastomer / gel material is obtained. It was. With an average functional group number of 1.6, the desired elastomer gel was not obtained. On the other hand, the polyurethane elastomer gels obtained from the compositions of Comparative Examples 2 to 4 that did not use the component (A) were insufficient in non-staining properties and heat resistance.

  In addition, in spite of using the components (A), (B) and (C) of the present invention, the compositions of Comparative Examples 5 to 8 having a high average functional group number of the polyol in combination with the trifunctional polyol. As shown in Table 2, the cured product obtained from No. 1 did not have satisfactory flame retardancy, and the surface hardness increased according to the amount of trifunctional polyol.

  With regard to the plasticizer, when the number of hydroxyl groups in the component (A) is 2.0 per molecule, the cured products obtained from the compositions of Comparative Examples 1, 2, and 5 that do not use the plasticizer all have surface hardness. The polyurethane elastomer gel obtained from the compositions of Comparative Examples 9 to 12 using a plasticizer other than the component (C) of the present invention has high flame resistance and satisfactory flexibility. In Comparative Examples 9 and 10 using phthalic acid ester, contamination by bleed was observed.

  When the average number of hydroxyl groups per molecule of the component (A) is 1.8, it is appropriate to use Example 6 in Table 4 as compared with Comparative Example 1 in Table 1 without using the component (C). A polyurethane elastomer gel having a surface hardness was obtained. In the case of such a component (A), when the component (C) is used, heat resistance and flame retardancy are lowered.

  The polyurethane elastomer gel obtained from the composition of the present invention has excellent flame retardancy without using a halogen-based or phosphorus-based flame retardant, and has excellent flexibility, non-contamination and heat resistance. Therefore, it can be widely used in the electronics field, and is particularly suitable as an impact protection material for HDDs.

Claims (13)

(A) a hydroxyl group-containing compound derived from a higher fatty acid containing one hydroxyl group and having an average of 1.9 to 2.0 hydroxyl groups per molecule and a number average molecular weight of 600 or more;
(B) an isocyanate compound having an average of 2.0 to 3.0 isocyanato groups per molecule or a diol derivative thereof; and (C) a higher fatty acid glyceride, provided that the hydroxyl group remaining in the glycerin moiety and the higher fatty acid is carbon A curable composition containing a modified hydroxyl group of a higher fatty acid having a hydroxyl group in a chain to give a low-hardness urethane elastomer / gel material.   The composition according to claim 1, wherein (A) is a diol derived from castor oil fatty acid or hydrogenated castor oil fatty acid. (A) a hydroxyl group-containing compound derived from a higher fatty acid containing one hydroxyl group and having an average of 1.7 or more and less than 1.9 hydroxyl groups per molecule and a number average molecular weight of 600 or more; B) Isocyanate compounds having an average of 2.0 to 3.0 isocyanato groups per molecule or diol derivatives thereof;
And a curable composition which is substantially free of the above (C) and gives a low-hardness urethane elastomer gel material.   The composition according to claim 3, wherein (A) is a hydroxyl group-containing compound derived from castor oil fatty acid or hydrogenated castor oil fatty acid.   The composition according to claim 1, wherein (B) has an average of 2.0 to 2.5 isocyanato groups in the molecule.   The composition according to claim 5, wherein (B) is diphenylmethane-4,4'-diisocyanate or a diol derivative thereof.   The composition of any one of Claims 1-6 whose molar ratio of the isocyanate group of (B) and the hydroxyl group of (A) is 0.95-1.10.   The composition according to any one of claims 1 to 7, wherein (C) is an acetylated hydroxyl group-containing higher fatty acid glyceride.   The composition according to claim 8, wherein (C) is acetylated ricinoleic acid triglyceride.   Furthermore, the composition of any one of Claims 1-9 containing 1 or more types of a catalytic amount of amines, carboxylic acid metal salt, an organotin compound, or a metal chelate compound.   A low-hardness polyurethane elastomer gel material obtained by curing the composition according to any one of claims 1 to 10.   The elastomer gel material according to claim 9, wherein the hardness according to Asker CsC2 hardness meter is 1 or more, and the hardness according to JIS K7312 is 40 or less according to a type C hardness tester.   The elastomer gel material according to claim 11 or 12, which does not contain a halogen-based or phosphorus-based flame retardant and has a flame retardancy of 94V-0 according to UL94 flame retardant standards.