JPH0448809B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a highly reactive, low-odor SH group-containing polymer by removing coexisting low molecular weight SH group-containing compounds using a thin film evaporator. SH group-containing polymers have traditionally been widely used in adhesives, sealants, etc. by utilizing the reactivity of SH groups. SH group-containing polymers are produced by various methods, but one specific example is as described in U.S. Pat. It is produced by synthesizing and then reducing a portion of the -S-S- bonds of solid polysulfide with alkali hydrosulfide. However, the SH group-containing polymer produced by the above method has a considerable range in its molecular weight distribution, and various low molecular weight SH group-containing compounds are inevitably produced as by-products during the production process of the above polymer. To give a further example, SH as described in U.S. Pat.
There is a method for producing group-containing polymers, but in this production method, β, which is added to introduce SH groups,
It is impossible to completely react a low molecular weight SH group-containing compound such as β'-dimercapto diethyl ether from the viewpoint of reactivity, and some of the low molecular weight SH group-containing compound remains unreacted. Low molecular weight SH group-containing compounds that coexist in SH group-containing polymers that are by-produced or remain unreacted during the manufacturing process of these SH group-containing polymers are
This causes an intense and unpleasant odor characteristic of conventionally known SH group-containing polymers, and such unpleasant odor has been regarded as one of the major drawbacks. Furthermore, when SH group-containing polymers are used in adhesives, sealants, etc., low-molecular SH group-containing compounds not only act as impurities that do not contribute to performance such as mechanical strength, but also degrade the polymer.
During reactions such as crosslinking and curing that utilize SH groups, the SH groups of low molecular weight SH group-containing compounds are
Because the polymer reacts competitively with groups, it takes a long time for the polymer to develop sufficient properties as a crosslinked or cured product, resulting in the disadvantage that the reactivity of conventionally known SH group-containing polymers is low. was inviting. In particular, conventional one-component adhesives and sealants using SH group-containing polymers have extremely slow curing speeds. In addition, by the conventionally known manufacturing method as described above,
Substantially eliminates harmful low molecular weight SH group-containing compounds, i.e.
It is extremely difficult to synthesize SH group-free polymers that do not adversely affect the odor or reactivity of SH group-containing polymers;
Low molecular weight SH group-containing compounds that coexist in group-containing polymers generally have a high boiling point, and SH group-containing polymers have very high viscosity. It has been difficult to produce polymers containing SH groups. In view of the current situation, the present inventors have developed a conventional SH
As a result of extensive research to solve these problems with group-containing polymers, we have found that by removing the low molecular weight SH group-containing compounds that coexist in the polymer using a specific separation method, the unpleasant odor can be improved and the reactivity can be improved. The present inventors have discovered that a SH group-containing polymer with improved properties can be obtained, leading to the present invention. That is, the present invention
When producing polymers containing groups, low molecular weight SH group-containing compounds coexisting in the polymer are removed by distillation under vacuum conditions of 1.5 mmHg or less using a thin film evaporator equipped with a built-in condenser. The present invention provides a method for producing a low-odor SH group-containing polymer with high odour. The low molecular weight SH group-containing compound in the present invention is
In the manufacturing process of conventionally known SH group-containing polymers, one or more molecules remain as a by-product or unreacted.
It is a compound that has an SH group in its molecule and has a sufficiently low molecular weight to emit a bad odor and reduce the reactivity of SH group-containing polymers. The molecular weight range of low molecular weight SH group-containing compounds cannot be determined unambiguously because the upper limit of the molecular weight that no longer gives off a bad odor varies depending on the type of compound, but in general, SH group-containing compounds with a molecular weight of 300 or less, In the method of the invention, low molecular weight
It should be removed as a SH group-containing compound. Specific examples of low molecular weight SH group-containing compounds to be removed in the method of the present invention include 1,6-
dimercapto alkanes such as dimercaptohexane; dimercaptoaryl ethers such as p, p'-dimercaptomethyl diphenyl oxide;
Examples include dimercapto alkyl ethers such as β,β'-dimercapto diethyl ether, but the present invention is not limited to these specific examples. The thin film evaporator used in the present invention is a conventionally known device capable of forming a thin film on the evaporation surface using a wiper or the like and has a built-in condenser. In particular, when a high degree of vacuum of 1 mmHg or less is required, it is preferable to use a molecular distillation apparatus, which is a thin film evaporator having a built-in condenser. The thin film evaporator can be operated under any desired conditions, but preferably within a range that does not cause deterioration of the SH group-containing polymer. Heat and oxidation are thought to be the main causes of deterioration of SH group-containing polymers, but in the present invention, the inside of the thin film evaporator is
It is necessary to lower the evaporation temperature by reducing the pressure to below mmHg. At high pressures exceeding 1.5 mmHg, it is difficult to prevent deterioration of SH group-containing polymers. In addition, deterioration can be easily prevented by efficient methods such as water evaporation blowing or adding an azeotropic solvent to cause azeotropy. In addition, especially for oxidative deterioration, nitrogen,
This can be easily prevented by introducing a non-oxidizing gas such as carbon dioxide or helium. According to the method of the present invention, low molecular weight SH group-containing compounds, which cause the unpleasant odor of conventional SH group-containing polymers and the lack of curing reactivity when these polymers are used in adhesives and sealants, can be efficiently removed. can be removed, but the expensive low molecular weight removed
The SH group-containing compound can also be reused as a raw material for synthesizing SH group-containing polymers, and is also useful for reducing the manufacturing cost of SH group-containing polymers. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Example 1 An SH group-containing polymer was synthesized according to Examples 1 and 2 of Japanese Patent Application No. 129821/1982 (Japanese Unexamined Patent Publication No. 93907/1989). Analysis of the resulting SH group-containing polymer revealed that β,β'-dimercaptoethyl ether, a low molecular weight SH group-containing compound, was present in the polymer.
2.6% by weight, and the polymer had an unpleasant mercaptan odor. 120% of the polymer
℃, 1.5 mmHg using a thin film evaporator with a built-in condenser (manufactured by Shinko Feudler Co., Ltd. 2-03)
The SH group-containing polymer (hereinafter referred to as polymer (1)) was obtained. As a result of analyzing the obtained polymer (1), the content of β, β'-dimercapto diethyl ether in the polymer was reduced to 0.008% by weight,
The polymer had lost its unpleasant mercaptan odor. Example 2 A one-component sealant using the polymer (1) obtained in Example 1 was prepared as follows. Polymer (1) 100g dioctyl phthalate 140g,
A base paste was obtained by sufficiently kneading with 320 g of calcium carbonate and 25 g of titanium oxide. Separately, 0.1g of ferric dimethyldithiocarbamate, calcium carbonate
A curing accelerator paste was obtained by thoroughly kneading 4.0 g of the dioctyl phthalate and 3.0 g of dioctyl phthalate. Next, the obtained base paste and curing accelerator paste were sufficiently kneaded to prepare a one-component sealant (hereinafter referred to as sealant (1)). Comparative Example 1 A sealing material was formulated in the same manner as in Example 2, except that the SH group-containing polymer used in Example 1 before being injected into the thin film evaporator was used instead of polymer (1) in Example 2. A one-component sealant for comparison (hereinafter referred to as comparative sealant (1)) was prepared. Example 3 Thiokol LP-32, a SH group-containing polymer
Thiokol LP-32 (manufactured by Toray Thiokol Co., Ltd.) was injected into a thin film evaporator under conditions of 90°C and 0.01 mmHg while introducing nitrogen through a glass capillary to perform molecular distillation. The low molecular weight SH group-containing compound coexisting therein was removed to obtain an SH group-containing polymer (hereinafter referred to as polymer (2)) according to the method of the present invention. As a result of measuring the molecular weight distribution of the obtained polymer (2) by gel permeation chromatography, the content of low molecular weight SH group-containing compounds with a molecular weight of 300 or less in the polymer was found to be
0.005% by weight, and the unpleasant odor that the polymer had before molecular distillation had disappeared. The content of low molecular weight SH group-containing compounds with a molecular weight of 300 or less that coexisted in Thiokol LP-32 (manufactured by Toray Thiokol Co., Ltd.) before molecular distillation was 1.5% by weight. Example 4 A one-component sealant using the polymer (2) obtained in Example 3 was prepared as follows. A base paste was obtained by sufficiently kneading 100 g of polymer (2) with 37 g of octylbenzyl phthalate, 15 g of isodecyl adipate, 55 g of calcium carbonate, and 10 g of titanium oxide. To the obtained base paste, 12 g of strontium peroxide, 3 g of potassium fluoride, 0.5 g of 2-ethylhexane manganese, and 0.7 g of tetraethylthiuram sulfide were added under a nitrogen stream and thoroughly kneaded to obtain a one-component sealant ( A sealant (hereinafter referred to as sealant (2)) was prepared. Comparative Example 2 A sealing material was mixed in the same manner as in Example 4, except that Thiokol LP-32 (manufactured by Toray Thiokol Co., Ltd.) was used in place of polymer (2) in Example 4, and Comparative Example 1 was prepared in the same manner as in Example 4. A component type sealant (hereinafter referred to as comparative sealant (2)) was prepared. Example 5 The sealant (1), sealant (2), comparative sealant (1) and comparative sealant (2) obtained in Example 2, Example 4, Comparative Example 1 and Comparative Example 2 were Immediately after preparation, fill into an aluminum groove-shaped container with a length of 100 mm, width of 15 mm, and depth of 20 mm, and store at 20°C at 65%.
The sealant was left in an RH atmosphere to harden. Curing progresses from the surface of the sealant exposed to air, but if left for 1, 2, 5,
The curing reactivity of each sealant was evaluated by measuring the thickness of the cured film at each time point of 10, 20, and 30 days. The results are shown in Table 1. As is clear from Table 1, the curing reactivity of the sealing material (1) and the sealing material (2) using the SH group-containing polymer obtained by the method of the present invention is the same as that of the comparative sealing material (1) and the comparative sealing material, respectively. (2)
It can be seen that there is a significant improvement compared to .

[Table] Example 6 Sealing materials obtained in Example 4 and Comparative Example 2
(2) and comparative sealant (2) were injected into a 2 mm deep molding cell immediately after adjustment, at 20℃, 65%RH.
The sealant was left in an atmosphere for 2 to 50 days to cure the sealant, and a cured sheet with a thickness of 2 mm was created.
Dumbbell size 2 shapes were punched out from each cured sheet that had been left for 2, 5, 10, 20, 30, and 50 days, and these were used as test pieces to measure the tensile strength (100% modulus and Breaking strength)
was measured to evaluate the curing reactivity of the sealant. The results are shown in Table 2. As is clear from Table 2, the sealing material (2) using the SH group-containing polymer obtained by the method of the present invention has a
The development of 100 modulus and breaking strength is fast,
It can be seen that the curing reactivity is significantly improved.
In addition, when comparing the cured sheet of sealing material (2) after 10 days when the sealant is thought to have completely cured, and the cured sheet of comparative sealant (2) after 30 days, there is a difference between the two. Not only is there no difference in the tensile strength of the sealant (2), but the tensile strength of the sealant (2) has increased, and the polymer (2) obtained by the method of the present invention is not only not degraded but also has low molecular weight SH groups. It can be seen that since the contained compounds were removed, a sealing material with better physical properties of the cured product was obtained.

[Table] Comparative Example 3 30 g of the same SH group-containing polymer used in Example 1 was placed in a 250 ml eggplant-shaped flask and placed in a rotary evaporator (Yamato Scientific RE-51 model) consisting of a corrugated cooling tube and a liquid receiving flask. The eggplant-shaped flask was attached and evaporation was performed for 30 minutes at 120° C. and 1.5 mmHg to obtain a comparative SH group-containing primer. As a result of analysis of the comparison SH group-containing polymer obtained, the content of β,β'-dimercapto diethyl ether was reduced to only 0.2% by weight. Comparative Example 4 Thiokol LP-32 was heated to 0.01 at 170°C using the same rotary evaporator as used in Comparative Example 3.
Evaporation was performed for 30 minutes under mmHg conditions. As a result of analysis of the comparison SH group-containing polymer obtained, the content of the low molecular weight SH group-containing compound in the polymer was reduced to 0.01% by weight. Example 4 Using this comparative SH group-containing polymer
A one-component sealant was prepared in the same manner as in Example 6, and the tensile strength of the cured sheet was measured in the same manner as in Example 6. The results are shown in Table 3.

[Table] As is clear from Table 3, the tensile strength (100% modulus and breaking strength) of the one-component sealant obtained using the comparative SH group-containing polymer was significantly inferior. Comparative Example 5 Evaporation was carried out under the same conditions as in Example 1, except that the thin film evaporator was not equipped with a condenser. As a result of analysis of the comparison SH group-containing polymer obtained, the β,β'-dimercapto diethyl ether content was reduced to only 0.1% by weight, and an unpleasant mercaptan odor remained. Example 2 using this comparative SH group-containing polymer
Comparative sealing material (3) was prepared in the same manner as in Example 5, and the curing reactivity was measured in the same manner as in Example 5. The results are shown in Table 4. Comparative Example 6 The evaporation operation was carried out in the same manner as in Example 3 except that the thin film evaporator was operated under a vacuum condition of 3.0 mmHg. As a result of analyzing the comparative SH group-containing polymer obtained, it was found that the low molecular weight SH group-containing compound in the polymer was
The concentration decreased to only 0.12% by weight, and an unpleasant mercaptan odor remained. Example 4 Using this comparative SH group-containing polymer
Comparative sealing material (4) was prepared in the same manner as in Example 6, and the tensile strength of the cured sheet was measured in the same manner as in Example 6. The results are shown in Table 5. As is clear from Table 5, the tensile strength (100% modulus and breaking strength) of the one-component sealant obtained using the comparative SH group-containing polymer was significantly inferior.

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Claims (1)

[Claims] 1. When producing polymers containing SH groups, low molecular weight SH group-containing compounds coexisting in the polymer are evaporated using a thin film evaporator with a built-in condenser.
A method for producing a highly reactive, low-odor SH group-containing polymer, which comprises distilling and removing under vacuum conditions of 1.5 mmHg or less.