JPS641485B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a block polymer having a polychloroprene unit and a polyether unit.
The present invention relates to a method for producing a block polymer by reacting a liquid chloroprene-based prepolymer having 3 isocyanate groups, a prepolymer obtained by reacting a polyether polyol with a polyisocyanate compound, and a low molecular weight active hydrogen crosslinking agent. Conventionally, methods for producing polyurethane include a method of reacting a polyol such as a polyether polyol or a polyester polyol with a polyisocyanate such as tolylene diisocyanate or diphenylmethane diisocyanate, and a method of reacting a terminal isocyanate obtained by reacting a polyol with a polyisocyanate. The prepolymer with groups is treated with a low molecular weight active hydrogen crosslinker, such as ethylene glycol,
Low molecular weight polyols such as 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, polyamines such as 3,3'-dichloro-4,4'-diaminodiphenylmethane, methylene dianiline, etc. There is a way to harden it. Polyurethane produced by these methods usually has extremely excellent physical properties such as high elastic modulus, heat resistance, and oil resistance. Poor hydrolysis resistance against acids, alkalis, etc.
There are practical problems in fields where these physical properties are required. The present inventor conducted various studies to improve the disadvantages of polyurethane and found that by using a specific mixed prepolymer, it was possible to significantly improve the conventional problems, leading to the present invention. . That is, the present invention has (a) at least two isocyanate groups in the molecule and a number average molecular weight of 500 to 10,000.
liquid chloroprene prepolymer and (b) a polyether polyol and a polyisocyanate compound having a number average molecular weight of 500 or more and having at least two isocyanate groups in the molecule.
4000 prepolymer and the weight ratio of (a)/(b) is 15/85/15, (c) a low molecular weight active hydrogen crosslinking agent capable of reacting with isocyanate groups is added and allowed to react. The present invention provides a method for producing a block polymer having a polychloroprelene unit and a polyether unit. The block polymer obtained by this production method has superior heat resistance and durability compared to conventional polyurethane. The liquid chloroprene prepolymer used in the present invention has at least two isocyanate groups in the molecule, and its number average molecular weight is limited to within the range of 500 to 10,000. The bonding position of the isocyanate group introduced into the liquid chloroprene prepolymer molecule may be at the end of the molecule or randomly located within the molecule, but at least one of the isocyanate groups may be bonded to the end of the molecule. is preferred. The optimum number of isocyanate groups to be introduced into the liquid chloroprene prepolymer molecules is 2 to 4; if the number is less than 2, a sufficient cured product will not be obtained, and if it exceeds 4, the Liquid chloroprene-based prepolymers are necessarily very expensive and are economically disadvantageous. If the number average molecular weight of the liquid chloroprene-based prepolymer is less than 500, the number of crosslinkable points in the polychloroprene will be extremely small, crosslinking of the prepolymer will hardly proceed, and the heat resistance and hydrolysis resistance of the resulting block polymer will deteriorate. If it is greater than 10,000, the viscosity of the prepolymer mixture becomes extremely high, impairing workability. The method for producing the liquid chloroprene-based prepolymer used in the present invention involves using a monomer containing chloroprene as the main component and the formula

[Formula] (In the formula, n is 1 or 2, R is 1 to 3 carbon atoms
is a hydrocarbon group. ) A method in which a liquid chloroprene copolymer produced by copolymerization with a hydroxyl group-containing monomer represented by Although preferred from the viewpoint of compatibility with the polymer, the method for producing the liquid chloroprene prepolymer is not limited to the above method. Prepolymer obtained from polyether polyol and polyisocyanate compound used in the present invention (hereinafter referred to as polyether prepolymer)
has at least two isocyanate groups in the molecule, and its number average molecular weight is limited to within the range of 500 to 4,000. The optimum number of isocyanate groups in the polyether prepolymer molecule is 2 to 4, and in particular, if it is less than 2, a sufficient cured product cannot be obtained, which is not preferred. When the number average molecular weight of the polyether prepolymer is less than 500, the number of urethane bonds or urea bonds in the resulting block polymer increases when the prepolymer mixture is cured, and the heat resistance and hydrolysis resistance of the block polymer decreases. If the viscosity of the prepolymer mixture cannot be sufficiently improved and is greater than 4000, the viscosity of the prepolymer mixture tends to increase significantly, impairing workability, or the compatibility with liquid chloroprene prepolymers decreases. There is. Examples of polyether polyols used to form the polyether prepolymer include, but are not limited to, polyethylene glycol, propylene glycol, polytetramethylene ether glycol, and polyoxytetramethylene ether glycol. It's not a thing. Examples of polyisocyanate compounds used to form the liquid chloroprene-based prepolymer and ether-based prepolymer used in the present invention include hexamethylene diisocyanate, cyclohexane diisocyanate, 2,4-tolylene diisocyanate, 2,6- Tolylene diisocyanate, 2 and 3 monomers of 2,4-tolylene diisocyanate, xylene diisocyanate, m-phenylene diisocyanate, 4,4'-
Diphenylmethane diisocyanate, 3,3'-ditoluene-4,4'-diisocyanate, dianisidine diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-
Examples include, but are not limited to, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and triphenylmethane triisocyanate. In the present invention, the low molecular weight active hydrogen crosslinking agent used as a curing agent for liquid chloroprene-based prepolymers and polyether-based prepolymers includes:
Those with a molecular weight of 500 or less are preferable, such as ethylene glycol, propylene glycol, 1,4
- Polyols such as butanediol, 2-ethyl-1,3-hexanediol, trimethylolpropane, or 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane , methylene diamine, o-, m- or p-phenylene diamine, but are not limited to these. In the method for producing a block polymer of the present invention, the weight ratio of liquid chloroprene prepolymer to polyether prepolymer is 15/85.
~85/15, and if the liquid chloroprene prepolymer is less than 15 parts by weight, the block polymer produced when it is cured will not have sufficient heat resistance and hydrolysis resistance, and the liquid chloroprene prepolymer will not have sufficient heat resistance and hydrolysis resistance. If the chloroprene-based prepolymer exceeds 85 parts by weight, the thermosetting properties peculiar to chloroprene-based rubber will be noticeable, so the hydrolysis resistance will be excellent, but the hardness will tend to increase strongly during heat aging, which is undesirable. . The properties of the block polymer produced by the method of the present invention depend on the weight mixing ratio of the liquid chloroprene prepolymer and the ether prepolymer, the molecular weight of the liquid chloroprene prepolymer and the ether prepolymer, and the type of crosslinking agent. greatly affected. For example, relatively low hardness,
When producing a low modulus block polymer, it is necessary to use relatively high molecular weight ones as the liquid chloroprene-based prepolymer and the polyether-based prepolymer, or to use the liquid chloroprene-based prepolymer at a high usage ratio. It is desirable to use polyols as a crosslinking agent, or to use them in combination, and to obtain a block polymer with relatively high hardness and high modulus, increase the number of urethane bonds or urea bonds in the cured product. It is necessary to use relatively low molecular weight ones as the liquid chloroprene-based prepolymer and the polyether-based prepolymer, or use the liquid chloroprene-based prepolymer at a low usage ratio, or use a polyamine-based prepolymer with a relatively low molecular weight. It is desirable to use a crosslinking agent or to use them in combination. In the method of the present invention, the curing reaction between the liquid chloroprene-based prepolymer and polyether-based prepolymer and the low molecular weight active hydrogen crosslinking agent is determined by the type of low molecular weight active hydrogen crosslinking agent used and the intended use of the polyurethane, that is, the block polymer. It can be carried out in a wide temperature range from low temperature to high temperature, although it varies depending on the temperature. For example, when manufacturing polyurethane molded bodies, it is usually 50 to 150
C., preferably in the range of 80 to 120.degree. C., but when used as a sealant or adhesive, it is usually carried out at a temperature around room temperature. In addition, to accelerate the curing speed, organic tin compounds such as dibutyltin dilaurate and tin octylate, tertiary amines such as triethylamine, triethyldiamine, and N-methylmorpholine, 1,8-diazabicyclo-(5,4 ,0)-
Cyclic amidine compounds such as undecene and its organic acid salts can be used as appropriate. When producing a block polymer by the method of the present invention, if you want to obtain one with particularly excellent heat resistance and hydrolysis resistance, it is necessary to use a vulcanization reaction based on the polychloroprene structure in the molecule and a combination of isocyanate groups in the prepolymer. Since it is advantageous to allow the curing reaction with the low molecular weight active hydrogen crosslinking agent to proceed simultaneously, it is preferable to use a vulcanization accelerator for polychloroprene of a type that has low reactivity with isocyanate groups or does not react at all with isocyanate groups. Examples of these accelerators include, but are not limited to, metal oxides such as zinc white, magnesia, litharge, red lead, zinc butylxanthate, and the like. According to the production method of the present invention, it is possible to produce a wide range of block polymers, from high modulus elastomers with excellent tensile strength, tear resistance, and tear resistance to relatively low modulus elastomers. This product has dramatically improved heat resistance (heat softening resistance) and hydrolysis resistance, which are difficult points, and is also practically sufficient in terms of weather resistance, ozone resistance, adhesion, and oil resistance. It can be used for various purposes because it has high resistance. For example, it is suitable for producing lining materials, potting materials, sealing materials, waterproof coating materials, adhesives, molded products by casting, sponge materials, and the like. In carrying out the present invention, if necessary, inorganic fillers such as titanium dioxide, calcium carbonate, and carbon black, which are common compound components,
Prepolymers include petroleum oils, softeners such as phthalate esters and tar, resins such as phenolic resins and coumaron/indene resins, bituminous substances such as straight asphalt and blown asphalt, and solvents as viscosity modifiers for compounds. It can be added to a mixture and reacted with a crosslinking agent. Next, examples of the present invention will be described, but the present invention is not limited thereto. All amounts used in the Examples and Comparative Examples are expressed by weight. Furthermore, the prepolymers used in Examples and Comparative Examples were manufactured as follows. (1) Polymerization According to the polymerization recipe listed in Table 1, the polymerization temperature is 40~
Polymerization was carried out at 55°C for 10 to 20 hours to produce a liquid chloroprene polymer.

[Table] (2) Purification and isolation of liquid chloroprene polymer After removing unreacted monomers from the polymerization solution in (1) above by vacuum distillation, the polymer was washed with a large excess of methanol and purified. Then, the polymer toluene solution was treated in a vacuum evaporator to isolate a liquid chloroprene polymer. (3) Prepolymer production Prepolymer by reacting the liquid chloroprene polymer or polypropylene glycol obtained in (2) above with 4,4'-diphenylmethane diisocyanate at a reaction temperature of 80 to 100°C for 1 to 2 hours. was manufactured. The amount of 4,4'-diphenylmethane diisocyanate used was 2.1 times the equivalent of the hydroxyl group in the liquid chloroprene polymer or polypropylene glycol. The properties of the obtained liquid chloroprene-based prepolymer and polypropylene glycol-based prepolymer are shown in Tables 2 and 3, respectively. (4) Analysis of prepolymers The molecular weights of these prepolymers were measured using an everiometer. Further, the isocyanate group content was determined by treating each prepolymer with dibutylamine and then back titrating the remaining dibutylamine with a hydrochloric acid solution.

【table】

[Table] Example 1 A compound was prepared by blending a liquid chloroprene prepolymer having an isocyanate group in the molecule and a polypropylene glycol prepolymer together with various curing agents in a paint mill according to the formulation shown in Table 4. 2mm thick coated with mold release agent
The mixture was poured into a mold and press cured at 120°C for 1 hour to obtain a cured sheet. The obtained cured sheet
After curing at 20°C for 7 days, the performance was evaluated according to JIS K6301, and the results are summarized in Table 4. Tests No. 3 and No. 4 are comparative examples in which the terminal isocyanate prepolymer used in the present invention is a liquid chloroprene prepolymer or a polypropylene glycol prepolymer, respectively. As is clear from these results, the block polymer (cured product) obtained by the method of the present invention has significantly improved heat resistance and hydrolysis resistance compared to the comparative example, and also has arbitrary properties ranging from low modulus to high modulus. It is possible to form polyurethanes with modulus.

[Table] A liquid chloroprene prepolymer having an isocyanate group in the molecule and a polypropylene glycol prepolymer were mixed in a paint mill with various curing agents according to the formulation shown in Table 5, and a compound was mixed with a mold release agent. The mixture was poured into a mold with a thickness of 2 mm, and press cured at 120°C for 1 hour to obtain a cured sheet. 20 pieces of the resulting cured sheet
After curing at ℃ for 7 days, the performance was evaluated according to JIS K6301, and the results are summarized in Table 5. Test No. 7 is a comparative example in which a liquid chloroprene-based prepolymer not based on the present invention was used. From these results, it is clear that the block polymer obtained by the method of the present invention has excellent mechanical strength, heat resistance, and hydrolysis resistance. In addition, the cured sheet obtained in the comparative example had a rough surface, was highly adhesive and poorly cured.

【table】

[Table] Example 3 A so-called prepolymer method in which a crosslinking agent (curing agent) and zinc white were blended into a liquid chloroprene prepolymer and a polypropylene glycol prepolymer having isocyanate groups in the molecule according to the present invention to cause crosslinking. Block polymer (cured product) (Test No. 8), liquid chloroprene prepolymer having a hydroxyl group in the molecule, polypropylene glycol, and 3,3'-dichloro-4,4'- as a low molecular weight substance containing an active hydrogen atom. Table 6 shows the physical properties of a block polymer (cured product) (Test No. 9, Comparative Example) produced by the so-called one-shot method, in which diaminodiphenylmethane was blended with polyisocyanate as a curing agent and zinc white and crosslinked.
The blending method, crosslinking conditions and evaluation method were carried out in accordance with Example 1.

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Claims (1)

[Scope of Claims] 1 (a) A liquid chloroprene prepolymer having at least two isocyanate groups in the molecule and having a number average molecular weight of 500 to 10,000 and (b) a polyether polyol and a polyisocyanate compound produced by the reaction of The resulting molecule contains a prepolymer with a number average molecular weight of 500 to 4000 having at least two isocyanate groups, and the weight ratio of (a)/(b) is 15/85 to
A method for producing a block polymer having polychloroprene units and polyether units, which comprises adding (c) a low molecular weight active hydrogen crosslinking agent capable of reacting with isocyanate groups to a 85/15 mixture and causing the reaction to occur. 2 A liquid chloroprene-based prepolymer is formed by combining a monomer mainly composed of chloroprene with the formula [formula] (where n is 1 or 2, and R is a carbon number of 1 to 3.
is a hydrocarbon group. Claim 1, which is a reaction product of a liquid copolymer with a hydroxyl group-containing monomer represented by
A method for producing a block polymer as described in Section 1. 3. The prepolymer (b) has a number average molecular weight of 500~
4000, a reaction product of polypropylene glycol or polytetramethylene ether glycol and a polyisocyanate compound.