JPS60240716A - Production of polymer polyol - Google Patents

Abstract

PURPOSE:To obtain a modified polymer polyol of good long-term storage stability effectively, by reacting styrene in the presence of a polyol by using a specified organic peroxide as a radical polymerization initiator. CONSTITUTION:Styrene, alone or a mixture of 80wt% or above styrene with a comonomer, is reacted in the presence of a polyol by using an organic peroxide of the formula as a radical polymerization initiator. In the formula, R1 is t-butyl or t-amyl, and R2 is a 3-8C linear or branched alkyl. The polyol, having an MW in the range of 500-7,000 is preferable. The reaction temperature should be 80-160 deg.C. When it is below 80 deg.C, the conversion of monomers, especially, styrene, is poor and unreacted matter increases. The organic peroxide as an effective radical polymerization initiator is represented by t-butylperoxy isopropyl carbonate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing modified polymer polyols for use in the production of polyurethanes, particularly polyurethane foams.

More specifically, as a radical polymerization initiator, the general formula, R
100'(C-o)0R2 (wherein R1 represents a t-butyl and t-amyl group, R2 represents a straight-chain or branched alkyl group having 3 to 8 carbon atoms) A method for effectively producing a modified polymer polyol with good long-term storage stability by polymerizing styrene alone or a mixture of comonomers having a styrene content of at least 80% in a polyol in the presence of peroxide. It provides:

Conventionally, compounds and mixtures obtained by polymerizing vinyl monomers in polyether polyols and polyester polyols are called polymer polyols, and it is well known that they have been used as raw materials for polyurethane foams, polyurethane distomers, etc. The purpose of such polyol modification is to improve the physical properties of the polyurethane foam when it is foamed, that is, the durability represented by compression set and the operability during foaming.

It is said that these polymer polyols mainly contain a mixture of vinyl monomer polymers in the polyol, and some of these polymers are chemically bonded to the polyol to form a graft polymer. However, in reality, most vinyl polymers are thought to be dispersed in polyols, and as a result, the uniform dispersion and stabilization of vinyl polymers in polymers is important for the quality of polymer polyols. This will determine long-term storage stability.

In fact, poor dispersion stability of polymer polyols causes various disadvantages in the production of polyurethane foams.

It is known that the dispersion stability of polymer polyols is affected by the type of vinyl monomer used, and if the vinyl polymer and BoIJol have poor affinity, they will easily separate. Among the many radically polymerizable vinyl monomers, the monomer that exhibits particularly good stability is acrylonitrile, and conventionally commercially available polymer polyols are modified with acrylonitrile alone or a mixture of acrylonitrile and styrene as monomers. there were.

However, in polymer polyols produced using acrylonitrile and styrene as monomers, as the proportion of styrene increases, the affinity with the polyol decreases, resulting in an extremely low dispersion stability. It has been said that this causes a fraction II (solid-liquid) phenomenon. In fact, to date, there have been hardly any examples of modified polymer polyols made of styrene alone that have low viscosity and good dispersion stability.

However, sometimes there are polymerizable double bonds in the polyol chain,
Some methods have been devised to introduce reactive active groups in advance and use them to modify the polyol relatively easily, but this method has the disadvantage of complicating the process. Up to now, no method has been proposed for producing a modified polymer polyol with excellent dispersion stability by polymerizing styrene alone in a polyol that does not contain active groups such as polymerizable double bonds in the chain. is the current situation.

On the other hand, due to the toxicity of acrylonitrile itself,
There is a tendency to refrain from using it as a monomer,
Furthermore, it has been widely used as a radical polymerization initiator.
Azobisisobutyronitrile (AIB), an azo compound
The reality is that N) is also less likely to be used due to its own toxicity.

Under these circumstances, the present inventors homopolymerized styrene in advance in a polyol that does not contain active hydrogen or polymerizable double bonds, with the aim of stabilizing the dispersion of the overlapping mer. As a result of intensive research into a large number of organic peroxides as radical polymerization initiators, they discovered a surprising fact.

This excellent and effective organic peroxide is represented by t-butylbaroxyisopropyl carbonate, which has a half-life of 10 hours at 97°C, and has the following general formula R.
, -00(C=0)-OR2, and was found to provide good long-term storage stability of modified polymer polyols. (In the above general formula, R□ represents a t-butyl and t-amyl group, and □ represents a straight-chain or branched alkyl group having 3 to 8 carbon atoms).

Conventionally, azo compounds such as AIBN and organic peroxides such as dibenzoyl peroxide (BPO) are well known and common as radical generators, but when used only as radical generators. This seems to have been a choice made from the viewpoint of However, the efficiency of the initiator is clearly poor, and as a result, after the reaction is complete, a step must be included to remove a considerable amount of residual unreacted monomer under reduced pressure.

The method for producing a highly stable polymer polyol of the present invention solves these problems and improves both the equipment and the economy.

The polyol used in the present invention may be of any type as long as it is commercially available for urethane foam, but for example, one or two of propylene oxide or ethylene oxide may be used in water or a polyhydric alcohol. It is a common polyether polyol obtained by reacting seeds. Further, those having a molecular weight in the range of 500 to 7,000 are preferably used. Examples of commercially available products include San-X FA-703 (Sanyo Chemical Industries) and Hyflex 443 (Dai-Kogyo Pharmaceutical).

The polymerizable vinyl monomer used in the present invention is mainly styrene, but may also be any two-component mixture of, for example, acrylonitrile and styrene. It goes without saying that the compound may be any compound selected from many radically polymerizable vinyl monomers, and is not limited to styrene alone. Furthermore, the organic peroxide represented by the general formula R, -00(C=O)-0R2 used in the present invention is effective when used in a mixture with a comonomer having a styrene content of at least 80%. It is. The total amount of monomers used is 5 to 50 parts per 100 parts of polyol. However, it is desirable to use an appropriate amount depending on the purpose of use.

The reaction temperature in the present invention is 80 to 160°C, preferably 90 to 150°C. If the reaction temperature is 80° C. or lower, the reaction rate of monomers, especially styrene, will be poor and unreacted substances will increase. Furthermore, if an attempt is made to increase the reaction rate to a certain extent, the reaction time becomes longer, making it uneconomical. The reaction time, including the time for dropping monomers, polyols and organic peroxides, does not need to exceed 3 hours, and the step of removing unreacted substances by reducing the pressure after the completion of the reaction does not need to exceed 30 minutes.

This is because, in the present invention, the reaction rate is extremely high and the amount of residual monomer is extremely reduced, so that this post-treatment step may be omitted in some cases.

Organic peroxides as radical polymerization initiators that are effective in the present invention are typically synthesized by the general formula %, represented by t-butylperoxyiso-propyl carbonate, by the reaction of hydroperoxide and chloroformate. However, depending on the combination of R1 and R9 in the general formula, the following t-butylperoxy n-
Propyl carbonate, t-butylperoxy 1so-
Butyl carbonate, t-butyl peroxy mebutyl carbonate, t-butyl peroxy 5eC-butyl carbonate, t-butyl peroxy 3-methoxybutyl carbonate, t-butyl peroxy 2-ethylhexyl carbonate, t-amyl peroxy 1so-propyl carbonate, t-amylperoxy n-propyl carbonate, -amylperoxy 1so-7'' thyl carbonate, t-amylperoxy n-butyl carbonate, t-amylperoxy 5ec-butyl carbonate, t-amyl Examples include, but are not limited to, peroxy 3-methoxybutyl carbonate and t-amyl peroxy 2-ethylhexyl carbonate.The amount of this organic peroxide added is 0.00 parts per 100 parts of the total amount of monomers. The amount is 5. to 15 parts, preferably 1 to 10 parts.The radical polymerization initiator is not limited to the use of only one component represented by the above general formula R100(C-o)OR2. It is also possible to use it in combination with other low temperature active initiators.

The reaction format in the present invention may be a continuous type, a semi-batch type, or a batch type, and is not particularly limited. In the reactor, the polyol, monomer,
An example is a method in which the radical initiators are added separately or a mixture thereof is added dropwise.

The modified polymer polyol of the present invention can be used as a raw material for not only polyurethane foam, but also polyurethane distomers, adhesives, paints, sealants, etc., and can be applied to the same uses as ordinary polymer polyols. .

This will be further explained using an example below.

Examples 1 to 10 and Comparative Examples 1 to 3 A predetermined amount of polyol was filled in advance into an IJ glass flask equipped with a thermometer, stirring rod, dropping funnel, and nitrogen introduction tube, and the inside of the flask was filled with dry nitrogen. Replace several times.

The internal temperature of the flask is raised to a predetermined temperature while stirring. After the internal temperature reached a predetermined temperature, the radical polymerization initiator, monomer, and remaining polyol were added dropwise from the Ω-t within a predetermined time while stirring. After the addition was completed, the reaction was continued under stirring for a predetermined time, and then a vacuum treatment was performed at 5 mmHg for a predetermined time to remove unreacted residual monomers, decomposition products of the initiator, and the like.

Table 1 shows the results of Examples (1 to 10) and Comparative Examples (1 to 3) under each condition. As can be seen from this table, it is surprising that the initiators I, II, and m, that is, the organic peroxide represented by R□-0O(C=0)-0&, have relatively low viscosity and stable dispersion It has been found that a homogeneous modified polymer polyol with good properties can be obtained. Such a polymer polyolefin having an almost transparent appearance and excellent uniform dispersion could never be obtained by using AIBN or BPO (Comparative Example 1.2). What is further noteworthy is that there is no difference in the stability of the modified polymer polyol of the present invention, regardless of whether or not a residue removal step is performed by vacuum treatment in the final step. In conventional polyol modification using conventional AIBN, a step for removing unreacted residues is essential. Therefore, according to the present invention, post-treatment steps after polymerization are omitted, indicating the fact that the manufacturing time is shortened.

Claims (1)

[Claims] General formula, Rloo (c=o) 0R2 (wherein, R1 is t
- butyl and t-amyl groups, R2 represents a straight-chain or branched alkyl group having 3 to 8 carbon atoms) are used as radical polymerization initiators, in the presence of a polyol. A method for producing a polymer polyol, which comprises reacting styrene alone or a mixture with a comonomer having a styrene content of at least 80% or more.