JPH05310882A - Method for molding polyurethane - Google Patents

Abstract

PURPOSE:To obtain a polyurethane molding which is free from bleeding of a plasticizer and is very soft (low in hardness) for its high strengths. CONSTITUTION:A polyol component, a polyisocyanate component, and a cross- linker (a chain extender) are reacted in the presence of a monofunctional compd. and cured in a mold to give a polyurethane molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane molding method, and more specifically, it is an object of the present invention to provide a polyurethane elastomer molding having a high strength even though it is soft (low hardness).

[0002]

2. Description of the Related Art Conventionally, a thermosetting polyurethane elastomer molded article is molded by a so-called casting method in which a polyol component and a polyisocyanate component are cured in a mold by a crosslinking agent. As a molding method, mainly the one-shot method and the prepolymer method are widely used. The method for casting a polyurethane elastomer as described above has an advantage that a molded product having excellent physical properties can be produced at low cost with simple equipment, and the molded product is, for example, a seal, a gasket, a belt, It is used in a wide range of applications such as bushes, packing, gears, shoe soles, sealing agents, printing rolls, paper feed rolls, and solid tires.

[0003]

The cast polyurethane elastomer moldings are used in a wide variety of applications as described above. For example, printing rolls of various printing machines, paper feed rollers of various copying machines and printers, etc. As described above, there is a problem in that sufficient strength cannot be obtained in applications requiring extremely soft physical properties. As a method for solving such a problem, the strength is increased by increasing the crosslink density or the ratio of hard segments during casting, while the DOP, DN
There is a method in which a relatively large amount of a plasticizer for vinyl chloride resins such as P and DBP is included to finish the molded product softly. In this case, however, various problems due to the use of the plasticizer, such as plasticizer Various problems such as contamination of contact materials due to bleed-out and volatilization and changes in hardness over time have occurred. As another method, there is also a method of reducing the amount of the crosslinking agent to reduce the amount of urethane bond or urea bond, but in this case, particularly the tensile strength and tear strength of the obtained molded product are There is a problem that is insufficient.
Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and despite its high strength, it is extremely soft (low hardness) and has no problem of plasticizer bleed-out. It is to provide a molded product.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention relates to a polyol component, a polyisocyanate component and a crosslinking agent (chain extender).
In the polyurethane molding method of reacting and curing in a mold, a monofunctional compound is present in addition to the above-mentioned components.

[0005]

[Function] When molding a polyurethane elastomer by casting, by adding a monofunctional compound to the casting material and casting, it is extremely soft (low hardness) despite its high strength, Further, it is possible to provide a polyurethane elastomer molded product that does not have the problem of bleeding out of the plasticizer. Such an action is considered to be because the monofunctional compound is bonded as a pendant to the polyurethane main chain or has the same properties as polyurethane and is sufficiently compatible with polyurethane.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. The molding method itself of the present invention is
It may be the same as the conventional casting method for polyurethane elastomers, and for example, both the one-shot method and the prepolymer method can be used as they are. Further, each reaction component which is the main raw material may be a conventionally known component. For example, as the polyol component constituting the soft segment of the polyurethane elastomer, polyester polyols such as PEA, PBA, PDEA, and PHA, or copolyesters of these adipates, and trifunctional or higher monomolecular molecules such as TMP are used. Examples thereof include polyester adipates branched with a polyol, and polyesters using an aromatic acid such as phthalic acid or a special dibasic acid such as succinic acid as an acid component. In addition, AA type polyester polyol such as PCL, polycarbonate polyester polyol and the like are also used.

Further, as the polyether polyol, P
PG, PTMG, EO / PO modified PTMG, etc. may be used, and a mixture of polyester polyol and polyether polyol, polyether ester polyol, polybutadiene polyol, etc. may also be used. On the other hand, as the polyisocyanate component, TDI, 4,4
′ -MDI, 1,5-NDI, 3,3′-TODI,
1,6-HDI, IPDI, XDI, PPDI, CHD
A general-purpose polyisocyanate such as I is used. As the cross-linking agent (chain extender), a monomolecular glycol such as 1,4-butanediol, a monomolecular polyol such as TMP, and a monomolecular polyol such as hydroquinone diethylol ether, preferably 3,3′- Dichloro-4,4'-
Polyamines such as diaminodiphenylmethane (MOCA), methylenedianiline / salt complex, 1,2-bis (2-aminophenylthio) ethane, trimethyleneglycol-di-p-aminobenzoate, di (methylthio) -toluenediamine are used. To be done.

The monofunctional compound used in the present invention and mainly characterizing the present invention is a monofunctional active hydrogen compound and / or a monoisocyanate. Examples of the former include alcohols and monoamines. ,
Butanol, pentanol, caproyl alcohol, caprylyl alcohol, nonyl alcohol, capryl alcohol, lauryl alcohol, myristyl alcohol,
Cetyl alcohol, stearyl alcohol, sec-butanol, pentan-2-ol, hexane-2-ol,
Heptane 2-ol, Octane 2-ol, Nonane 2-
Examples thereof include primary to tertiary alcohols having 4 or more carbon atoms such as all, decane 2-ol, undecane 2-ol, tridecane-2ol, tetradecane 2-ol, pentadecane-2-ol and hexadecane-2-ol. Monoamines include butylamine, pentylamine, hexylamine, isohexylamine, heptylamine, 2
-Heptylamine, octylamine, 2-octylamine, decylamine, undecylamine, laurylamine, cetylamine, dihexylamine, diheptylamine, dioctylamine, N-methylhexylamine, N
Examples include primary and secondary amines such as -methyloctylamine and N-methyllaurylamine. Further, one end-capped diol in which one hydroxyl group of the polymer diol is esterified with an arbitrary acid, polycaprolactone obtained by using a monoalcohol as a ring-opening polymerization initiator, and the like can also be used, and the molecular weight of these compounds is 500. It is preferably about 4,000.

The monoisocyanate compound is obtained by reacting the above-mentioned amine with isocyanate, or by reacting the above-mentioned polyisocyanate with the above-mentioned alcohol or amine,
Examples thereof include one having one isocyanate group. The above monofunctional compounds can be used alone or as a mixture, and the amount used is 5 to 50% by weight, preferably 5% by weight based on the total components of the cast elastomer.
~ 15% by weight. If the amount used is too small, the effect of the present invention, that is, softening is insufficient, while if the amount is too large, the strength of the obtained molded product decreases. In the case of the monofunctional compound as described above, when the cross-linking agent (or chain extender) is a diamine, it is preferable to use an alcohol (polyol having one OH at one end). When the extender) is a monomolecular polyol, it is preferable to use a monoisocyanate compound. With such a combination, the polyurethane can be softened without significantly lowering the urethane bond, urea bond, etc. in the obtained polyurethane.

The method of the present invention is characterized by using the above-mentioned respective components, and the molding method itself and the use ratios of the polyol, diisocyanate and crosslinking agent (chain extender) may be the same as those in the conventional molding method and compounding. .. For example, in the one-shot method, all the reaction raw materials are added to the mixer at once and mixed and stirred, and then poured into a mold to perform primary curing to almost complete the reaction, and then released from the mold. Secondary cure. When the prepolymer method is adopted, the polyol and diisocyanate are reacted in advance to form a prepolymer, and other insufficient raw materials are mixed with this prepolymer to finally complete the reaction curing. In this case, generally, a stoichiometrically excess diisocyanate and a polyol are reacted to synthesize an NCO-terminated prepolymer, and a crosslinking agent (or a chain extender) and the above monofunctional compound are added in the next step to react. It is preferably cured. In this prepolymer method, if the monofunctional compound is added during the production of the prepolymer, the reaction balance may be lost and the strength of the resulting molded article may be insufficient, which is not preferable. The cast polyurethane elastomer molded article of the present invention obtained as described above has sufficient strength and excellent flexibility (soft feeling), and is particularly used in applications requiring a soft feeling and durability, for example, It is useful for various sealing agents, printing rolls, paper feed rolls, etc.

[0011]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, unless otherwise specified, “parts” and “%” in the text are based on weight. Example 1 and Comparative Examples 1-2 In the composition of components shown in Table 1 below, polyester polyol and diisocyanate (NC) dehydrated and defoamed at 80 ° C were used.
O = 1.06) was mixed and reacted in a dry nitrogen atmosphere, the cross-linking agent (and the monofunctional compound) heated to 110 ° C. was added thereto while stirring, and the mixture was stirred and mixed for several minutes, and then 1
The reaction solution is poured into a mold treated with silicon at 00 to 130 ° C, aged at 100 to 130 ° C for about 20 minutes until the reaction solution becomes a stable rubber, and then secondary cured for 10 to 15 hours after mold release to crosslink. The reaction was completed to obtain polyurethane elastomer molded products of the present invention and comparative examples. The hardness (JISA), tensile strength (Kg / cm ² ) and elongation (%) of the obtained molded product are shown in Table 1 below.

[0012]

[Table 1] According to the results shown in Table 1 above, the molded product of the present invention (Example 1) shows that the hardness is significantly lower than that of Comparative Example 1, but the tensile strength is hardly reduced. Further, as compared with Comparative Example 2 in which the amount of the crosslinking agent used was small, the hardness was not changed, but the tensile strength was remarkably improved.

Example 2 and Comparative Example 3 Adiprene L-100 and MOCA (and a monofunctional compound) dehydrated and degassed at 80 ° C. were mixed and reacted in a dry nitrogen atmosphere in the composition shown in Table 2 below to obtain 100. ~
The reaction solution is poured into a mold treated with silicon at 130 ° C., the reaction solution is aged at 100 to 130 ° C. for about 20 minutes until it becomes a rubbery state, and after the mold is released, secondary curing is performed for 10 to 15 hours to perform a crosslinking reaction. Upon completion, polyurethane elastomer moldings of the present invention and comparative examples were obtained. The hardness of the obtained molded product (JIS
A), tensile strength (Kg / cm ² ), elongation (%) and tear strength (Kg / cm) are shown in Table 2 below.

[0014]

[Table 2] Adiprene L-100: Terminal NCO Prepolymer by Reaction of TDI and PTMG According to the results of Table 2 above, the molded product of the present invention (Example 2) has significantly decreased hardness as compared with Comparative Example 3. Nevertheless, there is little decrease in tensile strength.

Example 3 and Comparative Example 4 In the component composition shown in Table 3 below, NCO prepolymer preheated to 70 to 80 ° C. and MOCA heated to 110 ° C. were used.
(And monofunctional compound) are mixed and reacted in a dry nitrogen atmosphere, and after defoaming, the reaction solution is poured into a mold treated with silicon at 100 to 130 ° C. until the reaction solution becomes a stable rubber-like substance.
Aged at 00-130 ℃ for about 20 minutes, 10-15 after mold release
Secondary curing was carried out for a period of time to complete the crosslinking reaction, and the polyurethane elastomer molded products of the present invention and comparative examples were obtained. The hardness (JISA) and tensile strength (Kg / c) of the obtained molded product
m ² ), elongation (%) and tear strength (Kg / cm) are shown in Table 3 below.

[0016]

[Table 3] According to the results shown in Table 3 above, the molded product of the present invention (Example 3) shows less decrease in tensile strength than the comparative example 4, although the hardness is significantly decreased.

[0017]

[Effects] According to the present invention as described above, it is extremely soft (low hardness) despite its high strength, and the monofunctional compound used can bleed out from the surface of the molded product. No cast polyurethane elastomer moldings are provided.

Claims (2)

[Claims] 1. A polyurethane molding method comprising reacting and curing a polyol component, a polyisocyanate component and a crosslinking agent (chain extender) in a mold, wherein a monofunctional compound is present in addition to the above components. Molding method. 2. The polyurethane molding method according to claim 1, wherein the monofunctional compound is an active hydrogen-containing compound and / or a monoisocyanate compound.