JPH0255442B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel polymer composition in which an inorganic compound and an organic polymer are strongly integrated. Regarding the polymerization of vinyl monomers, various polymerization methods such as radical polymerization, ionic polymerization, and coordination polymerization are known. There are not necessarily many polymerization methods that are industrially easy, such as those that require the blending of polymers or water management during ionic polymerization. In addition, although a few unique systems have been reported using non-catalytic polymerization methods that do not use a polymerization initiator, these methods have hardly been put to practical use from an industrial standpoint. For example, Journal of
Polymer Science (J.Polym.Sci.) Volume 40
179 pages (1959) and Journal of Polymer Science, Polymer Chemistry (J.Polym.Sci.
Polym.Chem.Ed) Vol. 14, p. 1811 (1976) reported a method for producing a polymer by aqueous polymerization of methyl methacrylate in the presence of sulfuric acid, but the polymerization activity was extremely low and a trace amount of polymer was produced. It has the fatal drawback that it can only be recovered. In view of the above-mentioned current situation, as a result of intensive studies, the present inventors have discovered that a vinyl monomer capable of radical polymerization in the presence of a specific inorganic acid is brought into contact with an inorganic compound as a third component. The present inventors have discovered that it is possible to obtain a novel polymer composition in which the polymerization activity of the polymer is significantly increased and the inorganic compound and organic polymer are strongly integrated, which cannot be obtained by conventional methods, and the present invention has been completed. Conventionally, the development of composite materials that mutually complement the properties of the constituent materials and create new effective functions by combining two or more types of materials has been actively conducted. Regarding combination with useful inorganic compound powder, for example, elastic modulus,
A wide range of performance improvements including heat distortion temperature and electrical properties have been reported. However, in this case, the properties of the composite materials are significantly different from each other, resulting in poor interfacial compatibility such as compatibility and adhesion, making it impossible to achieve a sufficient composite effect. It has an essential drawback that it cannot avoid deterioration of its original physical properties. To improve this point, a mechanochemical method involves grinding an inorganic compound in the presence of a reactive monomer to graft an organic polymer, and a radiation method involves irradiating an inorganic compound with high-energy radiation to graft an organic polymer. Attempts have been made to improve the interfacial affinity between organic polymeric substances and inorganic compounds using methods such as methods, but these require pulverization processes, radiation generation equipment, etc., resulting in complicated processes and a significant increase in manufacturing costs. There are major problems in terms of practicality. The present invention aims to solve the above problems by polymerizing vinyl monomers capable of radical polymerization in the presence of a specific inorganic acid and in a polymerization system in which an inorganic compound is dispersed. The present invention provides a method for producing a composition in which an inorganic compound and an organic polymer are strongly integrated. Generally, when vinyl monomers are simply polymerized in the presence of an acid under temperature conditions that do not cause a thermal polymerization reaction, the polymerization rate remains at an extremely low level even after several days of polymerization time. In contrast, according to the present invention, by adding an inorganic compound as a third component, a very specific polymerization activity is brought about, and a polymer with a high polymerization rate that is of practical value can be obtained in a few hours. . Furthermore, the present invention is characterized in that the interaction between the surface of the inorganic compound and the polymer applied by the method of the present invention is a strong bond that goes beyond adhesion in the sense of simple adsorption. The polymer has a significantly high molecular weight. In other words, when an inorganic material is combined with a material having a significantly different modulus of elasticity, such as a normal thermoplastic resin, the presence of the high molecular weight polymer having an elastic modulus intermediate between the two materials at the interface facilitates stress transmission. The present invention provides a polymer composition that exhibits excellent reinforcing properties. To give an example of an embodiment when carrying out the present invention, after suspending and dispersing an organic vinyl monomer and an inorganic compound in an aqueous medium under temperature conditions that do not cause a thermal polymerization reaction, a specific inorganic acid By adding and stirring, an aqueous heterogeneous polymerization reaction is caused, and the surface of the inorganic substance is uniformly and firmly fixed with the vinyl monomer polymer at a high polymerization rate over a predetermined polymerization time. be able to. At this time, it is an essential condition that the three components mentioned above are brought into contact with each other in coexistence, but it is not necessarily necessary to bring them into contact at the same time. That is, even if an inorganic compound pretreated with an inorganic acid is used, a similar polymer composition can be obtained by the method of the present invention without adding a new inorganic acid during monomer polymerization. The inorganic acid used in the present invention is selected from nitric acid, hydrochloric acid, and sulfuric acid, and when these acids are used, the polymerization activity is high, the obtained polymer has a high [η], and it is difficult to carry out gas phase polymerization. This is preferable because the resulting polymer particles undergo secondary aggregation to form appropriate particles without the generation of cullet. Among these, nitric acid and hydrochloric acid are preferred because they have extremely high polymerization activity. Inorganic compounds used in the present invention include oxides, hydroxides, chlorides, sulfates, sulfites, carbonates, phosphates, silicates, and Mixtures and complex salts of these are advantageous, but among them calcium sulfite, calcium sulfate, silicon dioxide, titanium oxide, antimony trioxide, talc, clay, aluminum oxide are useful for activating vinyl monomers and solidifying them with polymers. The coalescing effect is particularly remarkable, which is preferable. As the vinyl monomer used in the present invention, any ordinary vinyl monomer that can be radically polymerized can be used, but among them, methyl methacrylate has a particularly high polymerization activity, and is also highly compatible with the produced polymer and inorganic substances. It is particularly preferred because of its good coalescence properties. When using a mixture of two or more types of monomers, using methyl methacrylate as one component can be said to be a preferable application method, especially from the viewpoint of polymerization activity. According to the invention, the concentration of inorganic acid is about 0.05-100% by weight based on the total weight of inorganic compound and monomer;
Preferably 0.1 to 50% by weight, particularly preferably 0.5 to 50% by weight
Used in an amount of 30% by weight. In most cases, it is preferred to increase the amount of inorganic acid as the monomer content increases. The weight ratio of monomer or monomer mixture to inorganic compound used can vary within a wide range and is from about 500:1 to 1:5, preferably about
50:1 to about 1:1. The amount of water is about 1% to several hundred times, preferably about 10% to 10 times, based on the total weight of inorganic compounds and monomers. The reaction is preferably carried out at a temperature of about 10-100°C, preferably 20-80°C, under an atmosphere of an inert gas such as nitrogen.
It will be held in The specific reaction temperature here is selected as appropriate depending on the vinyl monomer used, but it is important to conduct the reaction at a temperature that suppresses thermal polymerization to a negligible degree, and not at a high temperature that would cause extremely thermal polymerization. When carried out, the integrity and homogeneity of the resulting complex is inhibited. Reaction time is 30 minutes to about 15 hours. The resulting complex is heated to about 10-300°C, preferably about
Can be dried at a temperature range of 50-200℃.
Note that the interaction between the surface of the inorganic compound and the polymer applied by the method of the present invention goes beyond adhesion in a physical sense due to simple adsorption or van der Waals forces, etc. This fact is clear from the fact that even after extraction treatment with a good solvent for vinyl polymers, a large amount of unextracted polymer is observed. Next, the present invention will be explained in more detail with reference to Examples. Example 1, Comparative Examples 1 to 4 38.7 g of calcium sulfite 1/2 hydrate as an inorganic compound was added to deionized water in a 500 ml four-necked flask equipped with a cooling tube, nitrogen introduction tube, stirring rod, and thermocouple for internal temperature detection. The mixture was suspended and dispersed in 280 ml and purged with nitrogen for 30 minutes. Next, 30.0 g of methyl methacrylate as a vinyl monomer was added under nitrogen flow and vigorous stirring. Next, the temperature of the reaction solution was raised to 50°C in a hot water bath, and after confirming that the added monomer was uniformly dispersed,
3.10 g of a wt % aqueous nitric acid solution was gradually added, and a polymerization reaction was carried out at the same temperature for 8 hours. After the polymerization was completed, about 2 g was sampled from the reaction solution, and the amount of remaining unreacted monomer was determined by gas chromatography using dioxane as an internal standard reagent to determine the polymerization rate. For comparison, the polymerization behavior when no inorganic compound was added and when no inorganic acid was added was also investigated by performing the same polymerization operation and post-polymerization evaluation. The results are shown in Table 1.

[Table] As is clear from Table 1, the system shown in Comparative Example 4 without the addition of an inorganic acid shows no polymerization activity at all, and the two-component system with different inorganic acids and vinyl monomers shows extremely low polymerization activity. In contrast, the monomer polymerization rate is significantly increased by the method of the present invention in which an inorganic compound is added as a third component, indicating that the practicality is dramatically improved. The polymerization situation of Example 1 was such that there was almost no cullet formation in the polymerization system, resulting in a clean polymerization form, and furthermore, the resulting polymer composition had excellent secondary flocculation performance and was a product that was extremely easy to wash and recover. was gotten. Comparative Example 5 Sulfite water (6%
The same procedure as in Example 1 was carried out except that 41 parts (aqueous solution, commercially available product) was used. Although the polymerization rate of MMA was as high as 79.8%, a large amount of cullet, which appeared to be due to gas phase polymerization, was produced and adhered to the walls of the polymerization vessel.
Furthermore, the resulting polymer composition did not undergo secondary aggregation and remained as ultrafine particles, making it difficult to wash and recover. Examples 2 to 3 Polymerization was carried out in the same manner as in Example 1 except that hydrochloric acid and sulfuric acid were used instead of nitric acid as the inorganic acid in Example 1, and the monomer polymerization rate was measured and evaluated. The comparison results are shown in Table 2.

[Table] As is clear from Table 2, the polymerization activity was extremely high for nitric acid and hydrochloric acid, and slightly lower for sulfuric acid. Approximately 10 g of the polymer composition obtained by the method of Examples 1 to 3 was weighed together with a cylindrical paper, and a 24-hour Soxhlet extraction test was conducted using benzene, which is a good solvent for methyl methacrylate polymer, as an extraction solvent. The polymer extraction rate and [η] of the extracted polymer of the composition were measured. For comparison, a composition coated with polymethyl methacrylate produced by kneading and dispersing inorganic powder (calcium sulfite) in a methylene chloride solution of polymethyl methacrylate and then evaporating the solvent (Comparative Example 6) Similar evaluations and studies were conducted on the compositions produced using a conventional radical polymerization catalyst (Comparative Examples 7 and 8). The results are shown in Table 3, and show that the polymer component in the composition shown in the comparative example was completely extracted in the 24-hour extraction test, whereas the polymer component in the composite obtained by the method of the present invention The extraction rate of components is small;
Most of it is not extracted and is strongly combined with calcium sulfite. Furthermore, it can be seen that this polymer has a significantly higher [η] than a polymer obtained by a conventional method.

【table】

[Table] Example 4 The reaction was carried out in the same manner as in Example 1 except that the type of inorganic compound was changed, and the results of evaluating the obtained composition are shown in Table 4.

[Table] As is clear from Table 4, although some inorganic selectivity with respect to polymerization activity is observed in the method of the present invention, the monomer polymerization rate is generally good. Example 5 The reaction was carried out in the same manner as in Example 1, except that one type of vinyl monomer or a mixture of two types shown in Table 5 was used instead of methyl methacrylate as the vinyl monomer, and the resulting composition was The evaluation results are shown in Table 5.

[Table] Methyl lylate Example 6 Into a Henschel mixer for powder kneading, 38.7 g of calcium sulfite and 3.10 g of a 61% by weight nitric acid aqueous solution were added, stirred thoroughly for 10 minutes, and then set in the same manner as in Example 1. The entire amount of the treated filler was suspended and dispersed in 280 ml of deionized water using a reactor, and nitrogen exchange was performed for 30 minutes. Next, 30.0 g of methyl methacrylate as a vinyl monomer was added under nitrogen flow and vigorous stirring. Next, the temperature of the reaction solution was raised to 50° C. in a hot water bath, and a polymerization reaction was carried out at the same temperature for 8 hours. After the polymerization was completed, the same evaluation as in Example 1 revealed that the monomer polymerization rate was 80.5%.
Moreover, the obtained composite was a composition in which the surface of the inorganic substance was uniformly and firmly fixed with the polymer of the vinyl monomer.

Claims (1)

[Claims] 1. At least one radically polymerizable vinyl monomer is polymerized in the presence of an inorganic acid selected from hydrochloric acid, nitric acid, and sulfuric acid in a polymerization system in which an inorganic compound is dispersed. A method for producing a polymer composition in which an inorganic compound and an organic polymer are strongly integrated. 2. The method for producing a polymer composition according to claim 1, wherein the main component of the vinyl monomer is methyl methacrylate. 3. Claim 1, wherein the inorganic compound is at least one selected from calcium sulfite, calcium sulfate, silicon dioxide, titanium oxide, antimony trioxide, talc, clay, and aluminum oxide.
A method for producing a polymer composition according to item 1 or 2.