JP6932038B2 - Flexible polyurethane resin, flexible polyurethane resin member with excellent vibration isolation, vibration damping and shock absorption using it - Google Patents

Description

The present invention relates to a flexible polyurethane resin having a rubber hardness of 50 or less but excellent in compression set and compression creep, and a flexible polyurethane resin member using the same which is excellent in vibration isolation, vibration damping and shock absorption.

Conventionally, there are known vibration-proof materials, vibration-damping materials, shock-absorbing materials, etc. that obtain a soft polyurethane resin having a low rubber hardness and utilize these vibration-proofing and shock-absorbing properties (Patent Documents 1 and 2).
However, lowering the rubber hardness has a problem that the compression set and the compression creep characteristics are lowered at the same time.

By the way, a flexible polyurethane resin having a rubber hardness of 50 or less and excellent in compression set and compression creep has not been proposed so far, and is used as a substitute for highly functional elastomers and rubber. The emergence of these flexible polyurethane resins as materials, new materials for cushioning, etc. was strongly expected from various industrial fields.

Japanese Unexamined Patent Publication No. 2001-316448 Japanese Unexamined Patent Publication No. 5-310878

The polyurethane resin used as the anti-vibration member deforms when it receives a load, and the amount of deformation increases with the passage of time.
Therefore, an object of the present invention is based on the finding that if a flexible polyurethane resin having excellent compression set and compressive creep property is used in a place where it is used under a load for a long period of time, it is extremely convenient as a cushioning material. It is an object of the present invention to provide a flexible polyurethane resin having excellent vibration property, shock absorption property and vibration isolation property.
Another object of the present invention is to solve the conventional problems, to have the same anti-vibration characteristics as the conventional product while having a rubber hardness of 50 or less, and to have excellent compression set and compression creep property. It is to provide a flexible polyurethane resin.
Further, another object of the present invention is to provide a flexible polyurethane resin member having excellent vibration isolation, vibration damping and shock absorption using the above-mentioned flexible polyurethane resin.

As a result of intensive studies in view of the above points, the present inventors have reacted a specific polyol with a prepolymer having an active isocyanate group at the terminal obtained from the reaction of a specific polyol oligomer and a polyisocyanate compound. The present invention has been made by finding that the urethane resin is a flexible polyurethane resin having a rubber hardness of 50 or less, excellent anti-vibration properties, and excellent compressive permanent strain and compressive creep properties. That is,
(1) The flexible polyurethane resin of the present invention is
A flexible polyurethane resin having a rubber hardness of 50 or less and excellent in compression permanent strain and compression creep, which is produced from a composition obtained by reacting the following (A) polyol component and (B) polyisocyanate component.
(A) The polyol component is
(A-1) A polyol having a functional group number of 2.5 to 3.5 and a molecular weight of 4,000 to 7,000 and having an active hydroxyl group at the end,
(A-2) A hyper-branched polymer having an active hydroxyl group at the end,
Consists of a mixture of
(B) The polyisocyanate component is
It is characterized by being composed of a prepolymer having an active isocyanate group at the terminal obtained by a reaction of a polyoxypolypropylene polyol having a number of functional groups of 2.3 to 3.5 and a polyisocyanate compound.
(2) The flexible polyurethane resin of the present invention is used in the above (1).
The hyper-branched polymer having an active hydroxyl group at the (A-2) end is
It is characterized by being a compound obtained by self-condensation of dimethanol-fatty acid.
(3) The flexible polyurethane resin of the present invention is used in the above (1) or (2).
The hyper-branched polymer having an active hydroxyl group at the (A-2) end is
It is characterized in that it is a compound (n = 1, 2, 3 ...) obtained by reacting {(Σ2 ⁿ ) -1} mol of ^{diisocyanate with triol (Σ2 n) mol.}
(4) The flexible polyurethane resin member of the present invention is characterized by being excellent in vibration isolation, vibration damping and shock absorption using the flexible polyurethane resin according to any one of (1) to (3) above. And.

The flexible polyurethane resin of the present invention deforms when it receives a load, and the amount of deformation increases with the passage of time, so that it is excellent in compression set and compression creep property. If it is used in a place where it is used under a load for a long time, it is excellent as a cushioning member, and can be used as a shock absorbing member, a vibration isolating member, or the like.

Further, for example, in a house having two or more floors, if the flexible polyurethane resin of the present invention is placed as a cushioning material between the beam supporting the floor and the floor, noise can be suppressed because floor vibration and impact on the floor can be suppressed. It also exerts an excellent effect as a suppressing member.

In order to achieve the above-mentioned object, the flexible polyurethane resin of the present invention is used.
It is characterized by being excellent in compression set and compression creepability with a rubber hardness of 50 or less, which is composed of a polyurethane resin obtained by reacting a polyol component (A) and a polyisocyanate component (B).
Here, the (A) polyol component is
(A-1) A polyol having a functional group number of 2.5 to 3.5 and a molecular weight of 4,000 to 7,000 and having an active hydroxyl group at the end,
(A-2) Consists of a mixture with a hyper-branched polymer (multi-branched polymer: HBP) having an active hydroxyl group at the end.
(B) The polyisocyanate component is
It is composed of a prepolymer having an active isocyanate group at the terminal obtained by reacting a polyoxypolypropylene polyol having a number of functional groups of 2.3 to 3.5 with a polyisocyanate compound.

The polyol (A-1), which is one of the (A) polyol components used in the present invention, is
It is necessary to have an active hydroxyl group at the terminal with a functional group number of 2.5 to 3.5 and a molecular weight of 4,000 to 7,000.
When the number of functional groups is less than 2.5, the resin tends to be an uncured composition, and when the number of functional groups is larger than 3.5, the rubber hardness becomes larger than 50, which is not preferable.
If the molecular weight is less than 4,000, the rubber hardness becomes larger than 50, which is not preferable, and if the molecular weight is more than 7,000, the degree of unsaturation of the polyol terminal becomes high, which causes reaction inhibition, which is not preferable.
The type of the terminal of the polyol is not particularly limited, but it is preferable to have a primary hydroxyl group or a primary hydroxyl group at least partially in order to surely proceed with the resinification of polyurethane.

Specific examples of the polyol (A-1) used in the present embodiment in order to achieve the above-mentioned object are known polyoxys from the viewpoint of liquid viscosity, price, ease of adjusting molecular weight and number of functional groups, and the like. Polyalkylene polyols are preferred.

As the polyoxypolyalkylene polyol, a known compound obtained by ring-opening addition polymerization of an alkylene oxide using a low molecular weight active hydrogen compound as an initiator can be used.
The low molecular weight active hydrogen compound referred to here is water, ethylene glycol, propylene glycol, diethylene glycol, butanediol, hexanediol, glycerin, trimethylolpropane, or a polyhydric alcohol using a mixture of two or more of these. Can be mentioned.

As a typical example of the polyoxypolyalkylene polyol, in addition to the polyoxypolyalkylene polyol using the above-mentioned initiator, a polyol blended with an acrylic polymer can also be preferably used.

Specific trade names of the polyoxypolyalkylene polyol include, for example, Exenol 837, 840, 850, or Exenol 911, 910, 940, which is a polyol blended with an acrylic polymer, and Preminol PML-7001, PML-7003, PML-. 7005 etc. (all manufactured by Asahi Glass Co., Ltd.) and the like can be mentioned. It is also possible to use a mixture of two or more of these.

Further, as long as there is no problem, known castor oil-based polyols, ε-caprolactone-based polyols, polytetramethylene polyoxyglycols, β-methyl-δ-valerolactone-based polyols, carbonate-based polyols and the like may be used. Two or more types can be used together.

The other polyol (A-2) used in the present invention is a hyper-branched polymer (multi-branched polymer) having an active hydroxyl group at the terminal, and is an AB _{type 2} monomer. Examples of the polycondensation system of the above include compounds obtained by self-condensation of dimethylol fatty acids.
Further, mention may be made of polyaddition with a compound of the diisocyanate with a triol as polyaddition system A ₂ B ₃ type monomer.
Polycondensation or polyaddition hyperbranched polymers (HBPs) are synthesized in one step by selecting an appropriate monomer to give a spherical-like molecular-shaped compound with no intramolecular pores (references below). See 1 and 2).
(Reference 1: Yang, G; M. Macromolecules, 32, 2215 (1999))
(Reference 2: Jikei, M .; Chon, S .; Kakimoto, M .; Kawauchi, S .; Imase, T .; Watanabe, J .; Macromolecules, 32,2061 (1999))

AB type _{2 monomer} Hyper branch polymer (HBP) having an active hydroxyl group at the end of the polycondensation system as dimethylol fatty, for example, compounds according to the self-condensation of such dimethylol propionic acid or dimethylol butanoic acid.
Specific trade names of this hyper-branched polymer (HBP) include, for example, Bolton H311, P500 (manufactured by Perstop).

The hyper branch polymer having terminal active hydroxyl groups of the polyaddition type of _A 2 _{B 3} type monomer (HBP) is a diisocyanate {(Σ2 ⁿ⁾ -1} moles triol (.SIGMA.2 ⁿ⁾ compounds reacting molar (N = 1, 2, 3 ...).
In this synthesis, ^{100 parts by mass of the total amount of {(Σ2 n} ) -1} mol of ^{diisocyanate and 100 parts by mass of triol (Σ2 n} ) mol was charged, and 100 parts by mass of toluene or methyl ethyl ketone was charged as a solvent, and the mixture was slowly refluxed at room temperature for 4 hours. After proceeding with the reaction, 0.0025 parts by mass of dibutyl-tin-laurate was charged into the reaction vessel and reflux-reacted at 80 ° C. for 4 hours, and then the reaction solution was desolvated at 80 ° C. under vacuum with an evaporator. Obtained by doing.

In the flexible polyurethane resin of the present invention,
(A) A polyol having an active hydroxyl group at the end having a number of functional groups of 2.5 to 3.5 and a molecular weight of 4,000 to 7,000, which constitute the polyol component, and
(A-2) The mixing ratio of the hyper-branched polymer (HBP) having an active hydroxyl group at the terminal is
When the total amount of (A-1) polyol and (A-2) polyol is 100 parts by mass,
That is, the (A-1) polyol / (A-2) polyol is 95 / 5-99.7 / 0.3. It is preferably 99/1 to 97/3.
If the amount of the (A-2) polyol exceeds 5, it is not preferable because the rubber hardness becomes high, and if it is less than 0.3, no effect on the compression set and the compression creep deformation amount is observed.

Examples of the diisocyanate include isophorone-diisocyanate (IPDI), diphenyl-methane-diisocyanate (MDI), tolylen-diisocyanate (TDI), hydrogenated MDI, and the like, and IPDI having a hard skeleton is preferable.
Examples of the above-mentioned triol include glycerin, trimethylol-propane and the like.

The polyisocyanate component (B) used in the present invention is obtained by reacting a polyoxypolypropylene polyol having 2.3 to 3.5 functional groups, which is less than the theoretical amount, with a polyisocyanate compound using a known technique, and having an active isocyanate group at the terminal. Those having a remaining amount of 2 to 15% by mass, preferably 2 to 9% by mass are preferable.
If the remaining amount of the active isocyanate group exceeds 15% by mass, the hardness of the obtained flexible polyurethane resin increases and the elongation decreases, which is not preferable. If it is less than 2% by mass, the viscosity of the prepolymer increases. It interferes with the production of flexible polyurethane resin.

As the polyisocyanate compound, an organic compound having two or more isocyanate groups in one molecule and having a reactive isocyanate group for the active hydrogen-containing functional group of the polyol is used. As an example of the polyisocyanate compound, general aromatic, aliphatic and alicyclic compounds can be used. For example, toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI). There are diphenylmethane diisocyanate (MDI), liquid modified MDI, xylylene diisocyanate, cyclohexyl diisocyanate, isophorone diisocyanate and the like, and TDI and MDI are particularly preferable. These polyisocyanate compounds can be used alone or in combination of two or more.

In the present invention, the reaction ratio of the (B) isocyanate component composed of the prepolymer having an active isocyanate group at the terminal to the (A) polyol component is the isocyanate group (NCO) of the prepolymer with respect to the hydroxyl group (OH) of the polyol. The equivalent ratio, that is, the NCO / OH ratio is 0.9 to 1.1, preferably 1.03 to 1.05.
If this equivalent ratio exceeds 1.1, it is not preferable because it tends to foam in the reaction process, and if it is less than 0.9, it is not preferable because the compression set and the amount of compression creep deformation become large. ..
The smaller the equivalent ratio, the lower the hardness of the obtained flexible polyurethane resin.

Here, an appropriate urethanization catalyst can be used in carrying out the urethanization reaction between the (B) isocyanate component and the (A) polyol component. As the urethanization catalyst, a known catalyst such as a tertiary amine compound or an organometallic compound can be used. For example, triethylenediamine, N, N-dimethylhexamethylenediamine, N, N-dimethylbutanediamine, diazabicyclo (5,4,0) undecene-7 (DBU) and DBU salt, bismuth tris (2-ethylhexanoate). , Titanium diisopropoxybis (ethylacetoacetate), lead octylate, dibutyltin laurate, etc. are suitable. However, the use of this urethanization catalyst is not an essential requirement of the present invention.

Further, although the polyurethane resin as an essential component according to the present invention can be used as a simple substance, the following components can be added.
First, a plasticizer can be added. This plasticizer can be mixed in an amount of less than 24% by mass based on the total amount of the (B) isocyanate component and (A) polyol component as main components (30 in the DINP column of Tables 1 and 2). Described as parts by mass).
When this plasticizer is added, the hardness of the obtained flexible polyurethane resin decreases as the amount of the plasticizer added increases, and the anti-vibration property (tan δ) increases, which is preferable in terms of anti-vibration performance. Therefore, the addition of this plasticizer makes it possible to control the hardness of the composition resin to some extent.
However, when the plasticizer is added in an amount of 24% by mass or more, the mechanical properties of the composition resin are significantly impaired, the hardness is lowered, the compression set is increased, and the amount of compression creep deformation is increased. In addition, bleeding due to the plasticizer is likely to occur.
Applicable types of plasticizers include ordinary plasticizers for polyurethane resins such as diethylhexyl phthalate, diisononyl phthalate (DINP), dibutyl phthalate, trischloroethyl phthalate, trischloropropyl phthalate (TMCPP), etc. Hexamol dinch (manufactured by BASF) (DINCH) and the like can be mentioned.

In addition, in order to improve the durability and stability of the resin, heat stabilizers, antioxidants, UV absorbers, UV stabilizers, fillers, etc. may be used as stabilizers as long as there is no problem. Two or more kinds can be mixed and used. Further, in addition to the above-mentioned ones, pigments, dyes, flame retardants, antifoaming agents, dispersants, surface modifiers, moisture adsorbents and the like can be appropriately added.

Thus, the (A) polyol component and the (B) polyisocyanate component used as raw materials are mixed at room temperature or in a heated state, respectively.
When the additive is mixed, it may be mixed with the polyol in advance, or it may be added at the time of mixing the main component.

After sufficiently mixing each of the above-mentioned components, defoaming is performed under vacuum, and the mixture is poured into a mold at room temperature to 120 ° C. to cause a urethanization reaction at room temperature to 120 ° C. for 2 days to 2 hours.
After that, a flexible polyurethane resin can be obtained by removing it from the mold.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
[Polyaddition-based hyper branch polymer _A 2 _{B 3} type monomer (HBP) Synthesis
In a four-necked separable flask equipped with a stirring blade, a reflux device, and a thermometer, 500 g of methyl ethyl ketone (MEK) was charged under a nitrogen gas atmosphere, and then 577 g (2.6 mol) of isophorone-diisocyanate was charged. ..
Next, a solution of 423 g of glycerin and 500 g of MEK was dropleted at room temperature with stirring, and the reaction was carried out for 4 hours while maintaining the temperature of the reaction solution at 40 ° C. or lower.
Next, 0.025 parts by mass of dibutyl-tin-laurate was charged into the reaction vessel as a reaction catalyst, and the mixture was reflux-reacted at 80 ° C. for 4 hours.
After completion of the reaction, the reaction solution was placed in an eggplant-shaped flask, and then deMEK was performed at 80 ° C. under vacuum using an evaporator. The obtained HBP had a viscosity of 56 Pa. At 25 ° C. It was a viscous liquid of s and had 4 functional groups. This is indicated by the symbol _{"A 2} B _{3 HBP".}

Hereinafter, Examples 1 to 9 of the present invention are shown in Tables 1 to 2. A comparative example will be specifically described with reference to Table 2. The materials shown in Tables 1 and 2 are as follows.

In the table, polyol 1 is a mixture of polyoxypolypropylene (terminal part ethylene) triol and an acrylic resin (number of functional groups 3, average molecular weight 6,010), and polyol 2 is polyoxypolypropylene (terminal part ethylene). ) Triol (3 functional groups, 6,500 molecular weight).
_Then, AB 2 HBP is a hyper branch polymer which is a self-condensation product of dimethylol propionic acid having terminal active hydrogen groups (Boltorn P-500, Perstorp _Co.), A ₂ B 3 HBP is terminated It is a hyper-branched polymer (4 functional groups) that is a polyaddition of isophoron-diisocyanate having an active hydrogen group and glycerin.
DINP is diisononyl phthalate (plasticizer).
Isocyanate 1 is a prepolymer (remaining amount of terminal active isocyanate group 9.1% by mass) obtained by reacting liquid diphenylmethane diisocyanate with polyoxypolypropylene triol (molecular weight 5,000) having 2.7 functional groups, and isocyanate 2. Is a prepolymer (remaining amount of terminal active isocyanate group 9.0% by mass) obtained by reacting diphenylmethanediisocyanate with polyoxypolypropylene triol (molecular weight 5,000) having 2.8 functional groups.
DBTL is dibutyl tin laurylate (catalyst).

The reaction is started by mixing the above materials with a homogenizer (3000 rpm / min) for 60 seconds according to the formulation shown in the table, the mixture is defoamed in vacuum, and the mixture is further prepared to have a thickness of 200 × 200 mm and a thickness of 20 mm. A sheet-like flexible polyurethane resin with a thickness of 200 x 200 mm and a thickness of 5 mm is formed by casting into an open silicone mold, continuing the reaction at a temperature of 100 ° C. for 2 hours, then removing the mold, and then curing at room temperature for 7 days. Got

Then, the following experiments were carried out on this sheet-shaped flexible polyurethane resin, and the results are shown in Tables 1 and 2.
Examples 1 to 9 of the present invention are shown in Tables 1 to 2, and Comparative Examples 1 to 3 are shown in Table 2.

In the table, the numerical unit in the columns of "Polyol 1", "Polyol 2", "Isocyanate 1", "Isocyanate 2", "Plasticizer (DINP)", and "Catalyst (DBTL)" indicates the number of parts by mass. ..
The OH / NCO equivalent ratio in the table indicates the reaction ratio between the (B) isocyanate component and the (A) polyol component.

The "rubber hardness" is a numerical value as a result of measurement using a spring-type rubber hardness tester (A type) according to JIS K6301.
Further, "compression permanent strain (evaluation)" is measured according to JIS K6301 (compression rate 50%, 70 ° C., 24 hours) and displayed as a permanent strain amount (%) with respect to the compression deformation length.
Here, the meanings of ◎, ○, ×, and XX shown as the evaluation of the compression set are ◎ for those with a permanent strain of 5% or less, and ○ for those with a range of more than 5% and 10% or less. Those in the range of more than% and 20% or less were designated as x, and those exceeding 20% were designated as XX.
The natural rubber used as the anti-vibration material was 30 to 50% (evaluation XX).

The "vibration-proof property (tan δ)" was measured by a dynamic bending test (viscoelastic analyzer RSA-II, Rheometric, Inc.) using the obtained flexible polyurethane resin as a test piece having a thickness of 50 mm × 10 mm × 2 mm. It is a numerical value of the measurement result at 23 ° C.
The meanings of ◎, ○, △, and × shown as the evaluation of anti-vibration property (tan δ) are that those whose measured values are 0.3 or more are ◎, and those whose measured value is less than 0.3 and 0.2 or more are ○. Those having a range of less than 0.2 and 0.1 or more were evaluated as Δ, and those having a range of less than 0.1 were evaluated as ×.
The value of natural rubber for anti-vibration material was about 0.1 (evaluation Δ to ×).

Further, "15% strain compressive strength" was shown by a numerical value ^{of stress (unit: kg / cm 2} ) at the time of 15% strain after performing a compression test according to JIS K6911.

Then, for the obtained flexible polyurethane resins of "Example 1", "Example 2", and "Comparative Example 1", a "compression creep test" was performed ^{to accelerate the compression stress at 4.1 kg / cm 2} and the atmospheric temperature at 70 ° C. The measurement results were shown in Table 3.
The load of the compressive stress of 4.1 kg / cm ² used in the compressive creep test was set to a stress equivalent to the deformation of the test piece to be tested by about 20% at the initial stage of the load (instantaneous elastic deformation).

The numerical values in the table are the dimensional thickness (mm) of the test piece when creep deformed after a predetermined time elapses, the numerical value (before the test) is the product thickness, and the numerical value of (instantaneous elastic deformation) applies a load. It is the thickness of the test piece at the moment.

From the results of Tables 1 and 2, the flexible polyurethane resin of each example according to the present invention is maintained with a small change in hardness and compressive strength, and has excellent anti-vibration performance (tan δ) (anti-vibration rubber 2). ~ 3 times), it can be seen that it is extremely excellent in compressive permanent strain.
On the other hand, in Comparative Examples 1 to 3 in which the hyper-branched polymer (HBP) is not included in the formulation, it can be seen that the vibration isolation performance (tan δ) is excellent but the compression set is inferior.
From the results in Table 3, it can be seen that the flexible polyurethane resins of Examples 1 and 2 are superior in compression creep characteristics over a long period of time as compared with the resin of Comparative Example 1.

The flexible polyurethane resin of the present invention can be provided as a vibration-damping member, a vibration-damping member, a shock-absorbing member, etc., which are excellent in vibration-proofing characteristics, compression set, and compression creepability.
For example, the flexible polyurethane resin of the present invention is suitably used as an anti-vibration member because the amount of deformation increases with the passage of time under a load, and even if a load is applied for a long period of time, compression set and compression creep Since it has excellent properties, it is suitable as a cushioning member when used in a place in such an environment.
In addition, as another application, for example, in a house with two or more floors, if the soft polyurethane resin is placed as a cushioning material between the beam supporting the floor and the floor, floor vibration and impact on the floor can be suppressed. It can be suitably used as a noise suppressing member, and has extremely high industrial utility.

Claims (1)

A rubber hardness 30 to 50 (based on JIS K6301), compression set 1 .7 to 6.8% (measured value at a compression ratio of 50%, 70 ° C., after 24 hours based on JIS K6301), a flexible polyurethane resin sheet.
here,
The polyol component (A)
(A-1) number of functional groups of 2.5 to 3.5, polyoxyalkylene polyalkylene polyols having terminal active hydroxyl groups of the molecular weight 4,000～7,000 or the polyoxyalkylene polyalkylene polyol obtained by blending an acrylic polymer (However, the compound of A-2 below is excluded),
(A-2) A hyper-branched polymer having an active hydroxyl group at the end,
Is a mixture of
(B) the polyisocyanate component, the functionality from 2.3 to 3.5, a prepolymer having a terminal active isocyanate group obtained from the reaction of a polyoxyethylene polypropylene polyol with a polyisocyanate compound,
The hyper-branched polymer (A-2) is a compound obtained by self-condensation of a dimethylol fatty acid .