JPH0337217A - Ultrasoft elastomer composition - Google Patents

Abstract

PURPOSE:To obtain an ultrasoft polyurethane elastomer excellent in the susceptibility to changes and useful for a vibration-damping material or a shock- absorbing material by mixing an isocyanate-terminated prepolymer with a lactone polyol as a crosslinking agent. CONSTITUTION:An NCO-terminated prepolymer (A) (of an NCO content of 2-15wt.%) is mixed with a lactone polyol crosslinking agent (B) (a ring-opening polymer of beta-methyl-delta-valerolactone or epsilon-caprolactone of a number-average mol.wt. of 300-3000) and a diluent (C) in an amount of at most 200 pts.wt. per 100 pts.wt. total of components A and B to obtain a composition which can give an ultrasoft elastomer of a tensile elongation >=500% and a resilience <=50% within the range of Shore A hardness of 30-0. Component A is obtained by reacting an active hydrogen compound (e.g. castor oil polyol of a number- average mol.wt. of 700-3000 and an average functionality of 2.0-2.3) with an organic polyisocyanate such as tolylene diisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to elastomer compositions. Specifically, the present invention relates to an ultra-soft shock-absorbing composition having a low impact modulus, and an elastomer composition having extremely excellent mechanical properties, especially change followability.

[Problems to be solved by conventional technology and invention]

Polyurethane elastomer has superior mechanical strength and abrasion resistance compared to rubber, and has good weather resistance and chemical resistance, and can withstand long-term use. It has also been widely used in medical applications, printing rolls, seal materials, etc.

Recently, we have been making use of the flexibility of polyurethane elastomers.
It began to be used in a variety of ways, including as shock absorbers and vibration isolators.

Elastomers used for such purposes are required to have particularly flexible physical properties, and their hardness must be lowered to the edge of the barrel.

One of the known methods for producing such super-soft polyurethane elastomers uses a polymeric polyether diol to produce a theoretically compatible amount of 0. This is a method in which an amount of polyisocyanate compound corresponding to 2 to 0.8 is reacted.

In the ultra-soft composition produced by such a method, polymer chains are not sufficiently formed because the amount of the isothiaphor 1 compound is insufficient. Therefore, although it retains its own shape at room temperature, its surface is highly adhesive, which severely limits its use, and recovery from impact-induced displacement is slow.
The drawback was that it lacked heat resistance.

Another method is to obtain an ultra-soft composition by incorporating a large amount of a diluent into the polyurethane elastomer composition. However, the ultra-soft composition obtained by such a method significantly deteriorated the mechanical properties characteristic of general polyurethane elastomers, particularly the displacement followability, and could not withstand use. In addition, incorporating a large amount of diluent into the polyurethane elastomer composition may cause problems with the compatibility of the mixed components, separation may easily occur, making it difficult to obtain a uniform elastomer composition, and dilution of the elastomer composition. The drawback was that bleeding due to the agent was likely to occur.

[Means for solving problems]

An object of the present invention is to eliminate such drawbacks and provide an ultra-soft elastomer composition that has excellent mechanical properties, particularly excellent displacement followability.

The inventor of the present invention has conducted intensive research based on the above-mentioned objectives, and has found that in order to produce a polyurethane elastomer, a prepolymer having terminal isocyanate groups obtained by reacting a castor polyol with an organic polyisocyanate is used. It has been found that a homogeneous ultra-soft composition which has excellent compatibility with a diluent and a crosslinking agent and is reproducible without being influenced by moisture in the air can be obtained.

Furthermore, we have discovered that by using a lactone polyol as a crosslinking agent, it is possible to obtain a soft elastomer composition that has excellent mechanical properties, particularly displacement followability (tensile elongation), and that cannot be obtained using conventional crosslinking agents.

The present invention was completed based on this knowledge. That is, in producing a polyurethane elastomer, the present invention provides (a) a prepolymer having terminal isocyanate groups obtained by reacting an active hydrogen-containing compound and an organic polyisocyanate (bl lactone polyol crosslinking agent (C) (a) , (b) in an amount of not more than 200 coulometric parts per 11,100 parts by weight of the diluent.The present invention will be described in detail below.

The active hydrogen-containing compound used in the present invention to obtain the prepolymer having terminal isocyanate groups has an average functional group number of 2.0 to 2.3, preferably 2.0, and a number average molecular weight of 700 to 3,000, preferably 1.000~2.
000 castor oil-based polyol, which is generally commercially available, such as the trade name URECH,Y ((J Fuji Oil Co., Ltd.)).

Note that the average number of functional groups is 2. If it is smaller than 0, a sufficiently polymerized elastomer composition cannot be obtained, and 2.3
If it exceeds the desired content of isocyanate groups of 15% or less, a prepolymer having a desired isocyanate group content of 15% or less is undesirable due to gelation and increased viscosity.

In addition, if the number average molecular weight is less than 700, the hardness of the obtained elastomer composition will increase, which is undesirable.
,000 is not preferable because the reactivity of the prepolymer decreases.

Furthermore, as the active hydrogen-containing compound, polyols other than those mentioned above may be used in combination with the castor oil polyol as needed, within a range that does not cause any problem.

The organic polyisocyanate used in the present invention is an organic compound having two or more isocyanate groups in one molecule, and in the present invention, TDI, MDI,
It is necessary that it is at least one type selected from the group of liquid MDI.

In addition, as the organic polyisocyanate, isocyanate compounds other than those mentioned above may be used in combination with the isocyanate compound E as necessary within a range that does not cause any problem.

The prepolymer having a terminal isocyanate group used in the present invention is produced by reacting the active hydrogen compound and an organic polyisocyanate at 80 to 120° C. for several hours while stirring in a nitrogen stream. The obtained prepolymer has an isocyanate content of 2 to 15% by weight, preferably 3%.
Adjust the raw material ratio so that it becomes ~10% by weight. If the isocyanate content is less than 2% by weight, the viscosity of the prepolymer becomes high, which hinders the production of the elastomer composition. If the isocyanate content exceeds 115% by weight, the hardness of the resulting elastomer composition will increase or the tensile elongation rate will decrease, which is not preferred. The prepolymer may be one that is generally commercially available, for example, under the trade name U.
RtCN (Ito Oil Co., Ltd.) is mentioned.

In the present invention, it is necessary to use a lactone polyol as a crosslinking agent.

Here, the lactone polyol is obtained by ring-opening polymerization of β-methyl δ-valerolactone or ε-caprolactone using an active hydrogen compound as an initiator, and has a number average molecular weight of 300 to
3,000. Preferably it is a polyol of 500 to 1.500. If the number average molecular weight exceeds 3.000, sufficient reaction will not be obtained and the resulting composition will be difficult to cure, which is undesirable, while if it is less than 300, the resulting composition will have high hardness, which is undesirable.

The lactone-based polyol may be one that is generally commercially available, and for example, the trade names such as Plaxel (Daicel Chemical Industries, Ltd.) and Crapol P, L (Clar Corporation) can be used.

In addition, as the crosslinking agent, a known crosslinking agent for polyurethane resins or polyols may be used in combination with the lactone polyol as necessary within a range that does not cause any problems.

There is no particular restriction on the blending ratio of the above crosslinking agent and prepolymer, but usually the hydroxyl group of the lactone polyol (crosslinking agent)
prepolymer incyanate X (N
GO) molar ratio, that is, N GO/' OH, is 0.
7-1. 5, preferably 0°9 to 1.2, more preferably 0.95 to 1.05. If this molar ratio is outside the above range, the resulting elastomer composition will be difficult to cure.
Further, even if cured, the composition becomes a composition with poor mechanical properties, which is not preferable.

In the present invention, a diluent is used as a component of the composition in an amount of 200 parts per 100 parts by weight of the prepolymer and crosslinking agent.
It is necessary to use ~0 parts by weight, preferably 100-30 parts by weight. If the amount exceeds 200 parts by weight, it is not preferable because bleeding due to time-dependent transfer of the diluent mixed into the elastomer composition tends to occur.

Here, the diluent includes common diluents for polyurethane resins, such as tricresyl phosphate,
Tris(2-chloroethyl)phosphor) (TCEP
), tris(2,3-dichloropropyl) phosphate, tris(2,3-diglomobu-ovir) phosphate, dioctyl adipate, dibutyl sebacate, dibutyl phthalate) (DBP), dioctyl phthalate (DOP)
'J-, among others, TCEP, DBP, etc. are preferred. These diluents are used in combination with aiIA or 2N or more.

In the present invention, the mechanical properties of the composition, particularly the bow tensile strength,
Various organic and inorganic fillers can be used as desired to increase tensile elongation.

Among these, examples of inorganic substances include calcium carbonate,
Talc, clay, mica, graphite, aluminum hydroxide, calcium hydroxide, water rt/magnesium monide, @calcium acid, zinc oxide, aluminum oxide, titanium oxide, iron oxide, silicic anhydride, glass flakes, carbon black, silica stone, There is rock wool, etc. These shapes are powdery, scaly, and fibrous, and can be used as is, but the physical properties of the elastomer composition can be improved by subjecting the surface to titanium treatment, silicone treatment, etc. in advance.

Organic materials include debris, pine resin, resin powder, wood flour, animal and plant fibers, and artificial fibers.

In addition to the above, other materials such as minute hollow spheres can be used.

In carrying out the present invention, known urethanization catalysts such as tertiary amine compounds and organometallic compounds are used as necessary, such as triethylenediamine, 1,4-hexamethylenediamine, 1,4-butaneamine, octyl Examples include lead acid, dibutyltin uracrylate, and the like.

In addition, in the present invention, in order to increase the durability of the composition,
As the stabilizer, one or more of phase stabilizers, antioxidants, ultraviolet absorbers, and ultraviolet stabilizers may be used as required.

As the heat stabilizer, tetramethyl-thiuram disulfide, copper dimethyl-dithiocarbamate, etc. are used.

Positionally hindered phenols are used as antioxidants,
For example, product names Irganox 1010°1076 (manufactured by Ciba Geigy) and Yoshinox BHT, BB
(manufactured by Yoshitomi Pharmaceutical ■) is an example of this.

As the ultraviolet absorber, for example, the trade name Tinuvin P132
Benzotriazoles such as 7.328 (manufactured by Ciba Geigy ■) or benzophenones such as Tomisorb 800 (trade name, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) may be used.

In addition, as an ultraviolet stabilizer, for example, the product name Nanol LS
770.774, Tinuvin 144 (manufactured by Ciba Geigy Mari)
Preferably, positionally hindered amines such as

In addition to the various additives mentioned above, pigments, dyes, flame retardants, antifoaming agents, dispersants, surface modifiers, etc. can also be added as necessary.

In the ultra-soft elastomer composition of the present invention, the prepolymer, lactone polyol, and diluent may be stored separately until just before use, or the diluent may be mixed with the polyol, and they are mixed at the time of use.

When adding other substances, they may be added at the time of use, or may be mixed with the polyol mixture.

Thoroughly mix each component and mix at a temperature of preferably ~70°C.

Alternatively, pour into a mold at 40 to 60°C, and keep at room temperature -120°C, preferably 60 to 80°C, for 30 minutes to 1 day, preferably 3 to 80°C.
Reacted for 6 hours, fI! ! Super soft elastomer
Remove the composition from the mold.

The demolded elastomer composition product may be used as is, but it should be kept at room temperature to 80°C, preferably 40 to 60°C, for at least 1 day, preferably for at least 3 days, and more preferably for at least 7 days. is preferred.

[Action and effect]

The obtained elastomer composition had a uniform appearance, showed no surface tackiness due to phase separation of each component, and had a hardness (J
IS Z2246) A-0 to A-30 extremely flexible ultra-soft elastomer compositions. In addition, the rebound modulus (
JIS K6301 test thickness 10mm) is 0-50%
and a low shock absorbing composition. The mechanical property test values show extremely excellent displacement followability, with a tensile strength of 9.5 to 22 kg/Ci and a maximum tensile elongation of 500% or more in a tensile test (JIS K6301 B type dumbbell test piece).

The elastomer composition of the present invention changes with little stress due to its unique ultra-softness, has excellent displacement followability, and generates extremely little stress even when subjected to displacement, so it can be used as a vibration damping material, shock absorbing material, medical material, etc. sealing materials, gaskets,
Can be used as packing, soft adhesive, etc.

However, the uses are not limited to these.

[Example] The present invention will be described in more detail with reference to Examples below.

Examples 1 to 5 and Comparative Examples 1 to 6 The ingredients shown in Tables 1 to 2 (unit: parts by weight) other than the prepolymer components were mixed, then the prepolymer components were mixed, and this was mixed into a 200 mm x 200 mm x 3 mm thick It was poured into a silicone oven mold.

The mold was left as it was at room temperature for 2 days, and then cured at room temperature for 7 days to obtain a polyurethane elastomer composition.

Performance was evaluated using the following method. The results are shown in Examples 1-
2 and Comparative Examples 1 to 4 are shown in Table 1 Table 1 Table 2 Table 2 is for Examples 3 to 5 and Comparative Examples 5 to 6
are shown respectively.

The performance evaluation method is as follows.

Stability of O Mixed Components The oral stability of a mixed solution of crosslinking agent and diluent is determined by the presence or absence of separation of each component, and when there is no separation, it is marked as (good), and when there is separation, it is marked as (poor).

○Surface tackiness of the composition The compatibility after mixing the crosslinking agent, diluent, and prepolymer components is determined by whether the surface condition of the open side of the demolded elastomer composition is the same as that of the bottom side, or whether the tackiness is significantly stronger. If they are the same, it is marked as (good), and when the adhesiveness is strong, it is marked as (bad).

o Stability of the composition over time The presence or absence of diluent bleed after 30 days of the elastomer composition is determined, and when there is no bleed, it is marked as (good), and when there is bleed, it is marked as (poor).

0 hardness durometer - Hardness test method, measured using Nyoar hardness (Type A tester).

Impact modulus of O composition The rebound modulus is measured according to JTS K6301.

○Mechanical property test of composition The tensile strength and tensile elongation rate are measured using a B-type dumbbell test piece according to JIS K6301.

○Composition components Crosslinking agent 1: Kuraball L-1010 (Kuraray Co., Ltd.) Crosslinking agent 2: 1.4 butanediol crosslinking agent 3
: Ethylene glycol crosslinking agent 4: Plaxel 208AT, (Daicel Chemical Industries, Ltd.) TMHDA : Tetramethylhexanediamine DBTL Dibutyltin dilaurate Prepolymer A Nuric N-2024 (Ito Oil Co., Ltd.) Prepolymer B Nuric N-1002 (Ito Oil Co., Ltd.) Prepolymer C: A compound with a terminal isocyanate content of 991% obtained by reacting MDI with a polyol (polyoxypolypropylene glycol with 2 functional groups and 12,000 molecules).

(that's all margin)

Claims (1)

[Claims] (1) When producing a polyurethane elastomer, (
a) A prepolymer having terminal isocyanate groups obtained by reacting an active hydrogen-containing compound and an organic polyisocyanate (b) A lactone polyol crosslinking agent (c) 20 parts per 100 parts by weight of the total amount of (a) and (b)
An ultra-soft elastomer composition comprising 0 parts by weight or less of a diluent. (2) The active hydrogen-containing compound has an average functional group number of 2.0 to 2.
．． 3. The ultra-soft elastomer composition according to claim 1, which is a castor oil-based polyol having a number average molecular weight of 700 to 3,000. (3) The organic polyisocyanate is tolylene diisocyanate (TDI). , diphenylmethane diisocyanate (MDI), and liquid modified diphenylmethane diisocyanate (liquid MDI).
The ultra-soft elastomer composition described in . (4) The ultra-soft elastomer composition according to claim 1, wherein the prepolymer having terminal isocyanate groups has an isocyanate group content of 2 to 15% by weight. (5) The lactone polyol has a number average molecular weight of 300 obtained by ring-opening polymerization of β-methyl δ-valerolactone or ε-caprolactone using an active hydrogen-containing compound as an initiator.
3,000 to 3,000. (6) The urethane elastomer has a Shore A hardness of 30 to 0.
The ultra-soft elastomer composition according to claim 1, which has a tensile elongation of 500% or more in the range of . (7) The ultra-soft elastomer composition according to claim 1, wherein the urethane elastomer is a shock absorbing composition having a rebound modulus of 50% or less.