JPH11310665A - Thermoplastic elastomer and its composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an easily recyclable thermoplastic elastomer having organic salt structure so as to reversibly cause formation and destruction of pseudocrosslinked structure, through temperature change, with high heat resistance and low cold flowability. SOLUTION: This thermoplastic elastomer has an organic salt structure (pref. an onium salt structure bearing >=6C straight-chain alkyl group, esp. an organic salt structure consisting of a combination of ammonium and carboxylate anion). This elastomer is obtained, pref. by reaction between a raw material elastomer bearing reaction site capable of producing either cation or anion and a compound bearing reaction site capable of producing the other; wherein the raw material elastomer is pref. a highly carboxyl-modified liquid isoprene rubber in view of high dependency of its viscosity on temperature; the compound bearing reaction site capable of producing cation is pref. a straight-chain-bearing methylamine, however, for the highly carboxyl-modified liquid isoprene, stearylamine is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastomer having an organic salt structure, and more particularly, to a thermoplastic elastomer capable of reversibly forming and collapsing a pseudo-crosslinked structure by a change in temperature, and further contains the elastomer. The present invention relates to an elastomer composition for adhesives having excellent heat resistance.

[0002]

BACKGROUND OF THE INVENTION It has recently been discovered that when polyallylamine and long-chain alkyl acids are mixed, a salt is formed to form a thermotropic liquid crystal. It is believed that this is because polyallylamine and long-chain alkyl acids form a salt in a certain temperature range, and the salt acts as a mesogen (Ujiie et al., 1997 Liquid Crystal Symposium). Low molecular onium salts are
Antistatic agent, antibacterial agent (JP-A-9-111129), gelling agent (Japanese Patent No. 2700377), surfactant (JP-A-10-8041), latent polymerization initiator (JP-A-9-11041). 328507, Patent No. 2644
No. 301), an energy-sensitive acid generator (Japanese Patent Application Laid-Open No.
No. 202873)). Examples of the polymerizable compound having an onium salt and a polymer thereof include a pyridinium salt type (Japanese Patent Application Laid-Open No. 9-324015), an ammonium salt type (Japanese Patent Application Laid-Open No. 10-87741, and Japanese Patent No. 2668260), and phosphor. Ammonium salt type antibacterial agent (JP-A-10-81854), soap-free polymerization monomer (JP-A-2668260), antistatic agent (JP-A-10-7822, JP-A-9-328597), coating Formed antiperspirant polymer (Japanese Patent Application Laid-Open No. 10-500711), water-soluble resin (Japanese Patent No. 2641955), crosslinked polymeric ammonium salt (Japanese Patent Application Laid-Open No. 9-507687), and detergent (Japanese Patent Application Laid-Open No. Hei 9-507687). 235369). As an elastomer having an ionic bond formed by a metal ion, an ionomer is widely known. However, a thermoplastic elastomer in which an onium salt structure is introduced into a side chain of the elastomer to form a pseudo-crosslinked structure is not known.

[0003]

DISCLOSURE OF THE INVENTION The present invention relates to an elastomer which is capable of reversibly forming and collapsing a pseudo-crosslinked structure by a change in temperature, has excellent heat resistance, low cold flow property, and is easy to recycle. It is an object of the present invention to provide an elastomer composition for adhesives having excellent heat resistance.

[0004]

That is, the present invention provides an elastomer having an organic salt structure.

[0005] Preferably, the organic salt structure is on a side chain of the elastomer.

Preferably, the organic salt structure is an onium salt structure.

It is preferable that the organic salt structure has a hydrocarbon group.

It is preferred that the hydrocarbon group is an alkyl group.

It is preferable that the alkyl group is a linear alkyl group.

It is preferred that the alkyl group is an alkyl group having 6 or more carbon atoms.

[0011] The present invention also provides an elastomer composition for an adhesive containing any of the above elastomers.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0013] The present invention is an elastomer having an organic salt structure. In the present invention, the organic salt structure refers to an ion-bonded portion (mo) in which a functional group-modified product of a polymer constituting an elastomer and a functional group of a compound are bonded through an ionic bond.
ie, a structure having a non-metal ion in the ionic bond. Ionic bonds refer to bonds formed by electrostatic attraction between cations and anions. Therefore, the organic salt structure is formed by cations and anions other than metal ions.

Cations forming the organic salt structure include:
There is no particular limitation as long as it is other than a metal ion.
Nium ions are preferred. Onium ions are non-shared
Proton or cation type reagent
Generated by coordination, for example, ammonium
([R_ThreeNR ']⁺, R is a proton or other cation
(The same applies hereinafter)), phosphonium ([R_ThreePR ']⁺),
Arsonium ([R_ThreeAsR ']⁺), Stibonium
([R_ThreeSbR ']⁺), Oxonium ([R_TwoO
R ']⁺), Sulfonium ([R_TwoSR ']⁺), Sele
Nonium ([R_TwoSeR '] ⁺), Stanonium ([R
_TwoSnR ']⁺), Iodonium ([RIR ']⁺)But
No.

The anions forming the organic salt structure include:
Although not particularly limited, examples include a halide ion, a carboxylate anion, an alcoholate anion, a phenolate anion, a thiocarboxylate anion, and a sulfonate anion.

In the present invention, the structure of the organic salt is not particularly limited, and can be appropriately selected from the above-mentioned cations and anions. The structure in which the cation is the above-described onium ion, that is, , An onium salt structure is preferred, and an organic salt structure comprising a combination of ammonium and a carboxylate anion is particularly preferred.

The elastomer having an organic salt structure of the present invention comprises a raw material elastomer having a reactive site capable of forming an ionic bond and a compound having a reactive site capable of forming an ionic bond with the reactive site of the raw material elastomer. Combined via a bond. That is, the elastomer of the present invention comprises a raw material elastomer having a reactive site capable of generating one of a cation and an anion, and a compound having a reactive site capable of generating the other. The reaction site capable of generating a cation is not particularly limited, but includes, for example, an amino group,
Examples include a site containing an atom having an unshared electron pair such as an imino group. The reaction site that can generate an anion is not particularly limited. Examples thereof include halides (fluoride, chloride, bromide, iodide, and astatine), carboxyl groups, hydroxyl groups, phenoxy groups, thiocarboxyl groups, sulfonyl groups, and substituted products thereof.

The raw material elastomer having a reactive site capable of forming an ionic bond used in the present invention is modified or synthesized so as to have a reactive site capable of generating a cation or a reactive site capable of generating an anion. Elastomers can be used. Elastomers undergoing modification include ordinary rubber (including liquid rubber), thermoplastic elastomers, and thermosetting elastomers. Specifically, as the rubber, isoprene rubber, butadiene rubber,
1,2-polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, urethane rubber Liquid polyisoprene, liquid polybutadiene, liquid 1,2-polybutadiene, liquid styrene-butadiene rubber, liquid polychloroprene, liquid silicone rubber, liquid fluorine rubber, and the like. As the thermoplastic elastomer, polystyrene (for example, styrene-butadiene-
Styrene block copolymer, styrene-isoprene-
Styrene block copolymer, styrene-ethylenebutylene-styrene block copolymer), polyolefin, polyurethane, polyester, polyamide,
Examples thereof include polyvinyl chloride type. Examples of the thermosetting elastomer include a urethane type and a silicone type.

Examples of the elastomer modified so as to have a reaction site capable of generating an anion include a low carboxyl-modified liquid isoprene rubber, a high carboxyl-modified liquid isoprene rubber, a carboxyl-terminated butadiene rubber, a carboxyl-terminated nitrile rubber, a carboxyl-modified polybutane, and a carboxyl-modified polybutane. Highly reactive polybutene, ethylene-acrylic acid copolymer and the like can be mentioned. Among them, highly carboxyl-modified liquid isoprene rubber is preferred because its viscosity has a high temperature dependency. As a method for synthesizing the above-mentioned carboxyl group-containing elastomer, for example, a toluene solution containing a diene rubber such as butadiene rubber and mercaptoacetic acid is stirred at room temperature under a nitrogen atmosphere for 1 hour, the reaction mixture is precipitated in methanol, and the pressure is reduced. By drying, a diene rubber having a carboxyl group can be obtained.

The raw elastomer is preferably liquid at room temperature. This is because the elastomer of the present invention is easily mixed at the time of synthesis and has excellent workability.

As the compound having a reactive site capable of forming an ionic bond, the above-described compound having a reactive site capable of generating a cation or a reactive site capable of generating an anion can be used.

In the present invention, the organic salt structure is preferably an organic salt structure having a hydrocarbon group. That is, the compound having a reactive site capable of forming an ionic bond preferably has a hydrocarbon group at the reactive site capable of generating a cation or an anion. Here, the hydrocarbon group generally refers to a group consisting only of carbon and hydrogen, but in the present invention, those containing an oxygen atom in the form of ether, carbonyl, ester and the like are also included. Among the hydrocarbon groups, an alkyl group, particularly a linear alkyl group, is preferable, and an alkyl group having 6 or more carbon atoms is more preferable. This is because, at room temperature, the alkyl chains are liable to form a pseudo-crosslinked structure by ion-bonding with the raw material elastomer at room temperature, thereby easily becoming a rubber-like structure. As the compound having a reactive site capable of generating a cation, a primary amine is preferable, and a methylamine having a linear alkyl group, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine,
Decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, cetylamine, stearylamine and the like can be suitably used.

Preferred specific examples of the combination of the raw material elastomer and the compound include carboxyl-modified liquid isoprene rubber and stearylamine.

The ratio of the raw material elastomer to the compound in the elastomer of the present invention is such that the reaction site capable of forming an ionic bond in the compound is 0.1 to 1 equivalent of the reactive site capable of forming an ionic bond in the raw material elastomer. It is preferably 5 equivalents, more preferably 0.5 to 1.5 equivalents. If it exceeds 5 equivalents, or if it is less than 0.1 equivalent, the number of reaction sites not involved in ionic bonding increases, and the crosslinking efficiency deteriorates.

In the elastomer of the present invention, other additives such as various stabilizers, flame retardants, antistatic agents, coloring agents, fillers and the like are produced during or during the production without impairing the object of the present invention. It can be added later.

The method for producing the elastomer of the present invention is not particularly limited. For example, the raw material elastomer, the compound and, if necessary, other additives and a twin-screw extruder, a Banbury mixer, a kneader, or the like, are heated to about 120 ° C. A method of producing by melting and kneading under heating can be used.

The elastomer of the present invention has an organic salt structure, that is, a raw material elastomer and a compound are bonded through an ionic bond, and a pseudo-crosslinked structure is formed between molecules of the compound at room temperature. By heating to 100 ° C. or more, the pseudo-crosslinked structure collapses (a schematic diagram is shown in FIG. 1). The formation of a pseudo-crosslinked structure is observed as an increase in viscosity (decrease in fluidity). Further, the collapse of the pseudo-crosslinked structure is observed as a decrease in viscosity (increase in fluidity) or a decrease in hardness. This phenomenon is reversible, can be repeated any number of times, and is thermoplastic. Since the pseudo-crosslinked structure is thus formed, the elastomer of the present invention has higher heat resistance and lower cold flow property than the original raw material elastomer. Further, the elastomer of the present invention has a large fluidity at, for example, 100 ° C. or higher, and becomes extremely soft by heat, so that it can be recycled. Also,
When the elastomer of the present invention is blended with a resin or rubber that causes a cold flow at room temperature, it is possible to prevent the flow during extrusion and the cold flow. Therefore, the elastomer of the present invention can be suitably used as a flow inhibitor for resin or rubber, and is useful as a modifier for an adhesive.
Further, the adhesive containing the elastomer of the present invention as a modifier has excellent heat resistance and is useful. Examples of the adhesive include various hot melt adhesives. The content of the elastomer of the present invention is 9 parts with respect to 100 parts by weight of the total amount of the adhesive.
0 to 10 parts by weight is preferred.

[0028]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Preparation of Elastomer (Example 1) 5.07 g of stearylamine was added to carboxylic acid-modified liquid isoprene rubber 1 (Kuraprene LIR-410, manufactured by Kuraray Co., Ltd., having a carboxyl group content of about 5% by weight).
(18.8 mmol) was added, and the mixture was heated and stirred at 100 ° C. for 2 hours. After it was confirmed that a homogeneous solution was obtained, the mixture was allowed to stand for 24 hours to obtain an elastomer 1. The obtained elastomer 1 is rubbery at room temperature and heated to 100 ° C.
In the cases described above, fluidity was exhibited. This property change could be reversibly repeated by heating and cooling. (Comparative Example 1) Liquid isoprene rubber 2 having no carboxyl group instead of carboxylic acid-modified liquid isoprene rubber 1
Elastomer 2 was obtained in the same manner as in Example 1 except that (Claprene LIR-30, manufactured by Kuraray Co., Ltd.) was used.

[0029] ¹ H NMR measurement carboxylic acid-modified liquid isoprene rubber 1 of the spectrum, the stearylamine and elastomer 1 was analyzed by ¹ H NMR spectra. Measurement of IR Spectrum The IR spectrum of the carboxylic acid-modified liquid isoprene rubber 1 and the elastomer 1 was measured. Dynamic Viscoelasticity Measurement (DMA) The dynamic viscoelasticity measurement (DM ) of carboxylic acid-modified liquid isoprene rubber 1, elastomer 1, liquid isoprene rubber 2 having no carboxyl group and elastomer 2 was carried out.
A) was performed to measure the dynamic storage modulus (G ′), the dynamic loss modulus (G ″), and the loss tangent (tan δ) .The dynamic viscoelasticity measurement (DMA) was performed using a parallel cone (25 mm).
Torsion angle: 10 (rad / s), strain: 3
%, Load: 2 g.

FIG. 2 shows the measurement results of the ¹ H NMR spectrum.
4 to FIG. A signal derived from an amino group (δ = 2.6 to
2.7 (ppm)) was found only in stearylamine. This indicates that the amino group disappeared in the process of forming the elastomer 1. As a result of the IR spectrum measurement, the peak derived from the amino group of stearylamine was 16
06 cm ⁻¹ , peak attributable to the ammonium salt of elastomer 1 is 3436 cm ⁻¹ , 1580 to 1680 cm ⁻¹
Was observed. This suggests that, during the process of forming the elastomer 1, the amino group is ionized to form an ammonium salt. As described above, in the process of forming the elastomer 1, the carboxyl group of the carboxylic acid-modified liquid isoprene rubber 1 is ionized to generate a carboxylate anion, and the amino group of stearylamine is ionized to generate an ammonium salt. Can be estimated to be ion-bonded (Equation 1).

[0031]

Embedded image

FIG. 5 shows the results of the dynamic viscoelasticity measurement (DMA). In FIG. 5, the dynamic storage modulus of the carboxylic acid-modified liquid isoprene rubber 1 is G ′ ₁ , and the dynamic storage modulus, dynamic loss modulus, and loss tangent of the elastomer 1 are G ′, respectively.
₂ , G ″ ₂ and tan δ _{2. As} can be seen from FIG. 5, the inflection point of the dynamic storage modulus (G ′) of the elastomer 1 is higher than that of the carboxylic acid-modified liquid isoprene rubber 1 toward the high temperature side. Thus, it was confirmed that a pseudo-crosslinked structure was formed.
As compared with the liquid isoprene rubber 2 having no carboxyl group, a phenomenon in which the inflection point of the dynamic storage modulus (G ') was shifted did not occur.

[0033]

The elastomer of the present invention has a high heat resistance, a low cold flow property, a large fluidity at 100 ° C. or higher, and becomes extremely soft by heat.
It has the feature that it can be recycled. Therefore,
By blending the elastomer of the present invention with various thermoplastic elastomers and hot melt adhesives, it imparts properties such as being flexible at room temperature but having heat resistance, the ability to stop the flow during extrusion quickly, and being semi-permanently recyclable. It is useful because it can. Further, the elastomer composition for an adhesive containing the elastomer of the present invention has excellent heat resistance and is useful.

[Brief description of the drawings]

FIG. 1 shows a pseudo-crosslinked structure formed between molecules of a compound at room temperature in an elastomer 1 formed by forming an ionic bond between a raw material elastomer and a compound.
It is a schematic diagram showing how pseudo bridge | crosslinking collapses by heating above.

FIG. 2 ¹ H of carboxylic acid-modified liquid isoprene rubber 1
It is a figure which shows an NMR spectrum.

FIG. 3 is a chart showing a ¹ H NMR spectrum of stearylamine.

FIG. 4 is a view showing a ¹ H NMR spectrum of Elastomer 1.

FIG. 5: Dynamic storage modulus (G ′) of carboxylic acid-modified liquid isoprene rubber 1 and dynamic storage modulus (G ′), dynamic loss modulus (G ″) and loss tangent (tan δ) of elastomer 1 4 is a graph showing the temperature dependence of the present invention.

Claims (8)

[Claims] 1. An elastomer having an organic salt structure. 2. The elastomer according to claim 1, which has an organic salt structure in a side chain. 3. The elastomer according to claim 1, wherein the organic salt structure is an onium salt structure. 4. The elastomer according to claim 1, wherein said organic salt structure is an organic salt structure having a hydrocarbon group. 5. The elastomer according to claim 4, wherein said hydrocarbon group is an alkyl group. 6. The elastomer according to claim 5, wherein said alkyl group is a linear alkyl group. 7. The elastomer according to claim 5, wherein the alkyl group is an alkyl group having 6 or more carbon atoms. 8. An elastomer composition for an adhesive, comprising the elastomer according to claim 1.