JPS5817210B2 - Method for producing graft copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to so-called graft polymerization, in which a chain polymer compound is copolymerized with an unsaturated monomer in a branched manner.

Generally, unsaturated monomers are graft-polymerized onto fibers, threads, textiles, etc. to improve hygroscopicity, dyeability, texture, and antistatic properties. Improving the hygroscopicity of polymer powders for soil improvement, hygroscopic papers, absorbent cotton, etc. by graft polymerizing them onto powder, fibrous, or film-like polymer compound substrates using unsaturated monomers. The first objective is to increase the yield of the graft copolymer when graft polymerizing a water-soluble unsaturated monomer onto a substrate, and to obtain a homopolymer by polymerizing only the unsaturated monomer. The second purpose is to suppress production and enable continuous industrial production.

The first problem with conventional methods for producing graft copolymers is that the yield of the copolymer is extremely low because a homopolymer of unsaturated monomers is formed in the solvent. The problem with this is that it is not easy to separate the homopolymer from the copolymer.

For example, let us consider the case where a water-soluble unsaturated monomer M such as methacrylic acid is graft-polymerized onto a polymeric substrate A such as rayon based using an apparatus as shown in FIG.

Water W is used as the medium, and the substrate A is an unsaturated monomer M.
While passing through the aqueous solution, the monomer is absorbed and the graft polymerization bag is prepared under appropriate time and temperature conditions.

Radical catalysts for initiating polymerization include hydrogen peroxide and iron ions, but for practical purposes, even trace amounts of metal ions contained in water or other substances are sufficient.

In the figure, unsaturated monomer M is copolymerized with substrate A to produce graft polymer B, and is homopolymerized at a location other than substrate A in medium W, so a large amount of monomer M is required. On top of that, the concentration of the homopolymer in the medium W gradually increases, the viscosity becomes high and it loses its function as a medium, and at the same time, it prevents the diffusion and penetration of the monomer M into the substrate A, and the high viscosity increases in the next step. The separation of the kraft polymer from the homopolymer becomes cumbersome.

As a method to solve the above drawbacks,
No. 58 is known.

This method involves dissolving an inorganic neutral salt in an aqueous medium, causing the unsaturated monomer to undergo phase separation in the aqueous medium due to its salting-out effect, and allowing it to contact and permeate the substrate at a high concentration. It is made with a material with increased grafting efficiency.

However, even with this method, the water-soluble unsaturated monomer still dissolves in water, and a considerable amount of homopolymer is formed in water, reducing the yield of the graft copolymer and The disadvantage is that it is troublesome to separate the merging.

The present invention has solved the above problems, and as shown schematically in FIG. 2, a polymerizable water-soluble unsaturated monomer M is dissolved in a hydrophobic organic solvent C, and a hydroxyl group A polymeric substrate A having a hydrophilic group such as a carboxyl group, an acid amide group, or a nitrile group is impregnated with a small amount of water W, and the unsaturated monomer M is impregnated onto the substrate A by immersing it in the above solution. It is graft polymerized.

Examples of the water-soluble unsaturated monomer M used in the present invention include acrylic acid, methacrylic acid, dialkylamine ethyl methacrylate, hydroxyalkyl methacrylate, polyalkylene glycol monomethacrylate, polyalkylene glycol dimethacrylate, N-methylol acrylamide, and acrylamide. be.

Hydrophobic organic solvents C include petroleum ether, ligroin, petroleum naphtha such as cyclohexane, benzene,
Aromatic hydrocarbons such as toluene and xylene are most preferred, but other ethers1. Also ketones, esters, etc.

It is sufficient as long as it is insoluble in the aqueous medium.

Hydrophobic organic solvents generally dissolve water-soluble unsaturated monomers, but their homopolymers have the property of being poorly soluble or insoluble. Furthermore, as the polymer compound substrate A used in the present invention, nylon, vinylon, etc. , synthetic fibers such as acrylic, silk, cotton,
Natural fibers such as hemp and wool, regenerated fibers such as rayon and cupra, semi-synthetic fibers such as acetate, or powders such as starch, casein, polyacrylonitrile, polyacrylamide, nylon, and wood powder can be used, and film-like materials can also be used. Materials such as nylon, cellophane, poval, acetate, and semi-synthetic cellulose films can be used.

In other words, it has a shape with a large surface area and contains hydroxyl groups and
Any material may be used as long as it has a hydrophilic group such as a carboxyl group, an acid amide group, or a nitrile group, and has the property of absorbing water.

The following table shows the moisture content of some of the polymer compounds listed above, which indicates the degree to which they absorb water.

The water-absorbing polymer compound used in the present invention must have a moisture content of about 2.0 or more, and although polyester has hydrophilic groups, its moisture content is 0.4.
It is excluded from the present invention because it absorbs very little water.

Note that it can also be applied to sponge-like objects as special shapes.

As described above, the method of the present invention involves impregnating the polymer substrate A with a small amount of water W in advance and immersing it in a solution in which the water-soluble unsaturated monomer M is dissolved in a hydrophobic organic solvent C. Therefore, monomer M does not polymerize in organic solvent C, and only when it comes into contact with water W does polymerization start radically by metal ions present in extremely small amounts in water.

At this time, the monomer M is first incorporated into the substrate by dissolving in the water present in the substrate and on the surface of the substrate, and is transformed into a graft copolymer in the substrate at, for example, 80° C. for several hours.

Here, since the substrate has the property of absorbing water, the monomer M is easily incorporated into the substrate by the water absorbed by the substrate, but if it does not absorb water, the monomer M M is not easily incorporated into the substrate and graft copolymerization does not proceed.

This is the reason why polyester, which hardly absorbs water, was excluded as a polymer base.

As monomers change into copolymers in the aqueous phase, the monomer concentration equilibrium is broken near the boundary with the solvent phase, and the monomers migrate from the solvent phase to the aqueous phase.

So according to this method. The amount of monomer necessary for graft copolymerization with the polymeric substrate is replenished from the solvent phase, resulting in an extremely high graft polymerization rate.

For industrial mass production, it is desirable to use a suitable graft catalyst in order to shorten the time required for polymerization.

As the graft catalyst, it is necessary to use one that is insoluble in the hydrophobic organic solvent C and has water solubility.Hydrogen peroxide,
Peroxides such as potassium persulfate, or metal ions such as cerium ions, copper ions, iron ions, etc. can be used.

Figure 3 is a graph in which the horizontal axis shows the weight ratio of impregnated water to the substrate, that is, the water amount ratio, and the vertical axis shows the weight ratio of the grafted monomer to the substrate, that is, the weight increase rate. It is known that the weight increase rate has a peak value around the water ratio of 8.

This tendency is common regardless of the type of substrate, monomer, or presence or absence of a catalyst; if the amount of water is zero, no graft polymerization occurs at all, and the presence of a small amount of water is extremely important. I understand that.

At a water ratio of 8 or more, the weight increase rate decreases slowly, but
Since the grafting efficiency (copolymerized monomer weight/polymerized monomer weight) due to homopolymer production decreases rapidly,
The optimum value of the water ratio is within a very narrow range, and it has been experimentally found that a water ratio of 5 to 10 is a practically effective range.

According to the present invention, as described above, the water-soluble unsaturated monomer dissolved in the hydrophobic organic solvent does not come into contact with the catalyst (polymerization initiator), so it is difficult to cause thermal polymerization, and therefore the grafting efficiency is high and It is suitable for continuous production because there is no increase in viscosity due to homopolymer formation, and the amount of water that is pre-impregnated into the substrate only needs to be the amount required for graft copolymerization, and the organic solvent functions as a medium. Because I have Uke.

It is possible to minimize the formation of homopolymers,
In addition, the monomers are in an equilibrium state near the boundary between water and the organic solvent, and the monomers can be transferred to the water phase depending on the grafting reaction rate, so an appropriate amount of monomers is always involved in the copolymerization. By doing so, it is possible to prevent the formation of homopolymers.

Conventionally, graft copolymers have been obtained with many homopolymers attached, which makes it difficult to separate the homopolymer from the copolymer, and is hindered by the homopolymer on the surface of the substrate. Penetration of the monomer into the interior was inhibited, and for example, a weight increase rate of several tens of times or more could not be expected, but it is estimated that according to the present invention, a weight increase rate of several hundred times or more is possible.
Moreover, since the graft copolymer is obtained with almost no homopolymer attached, it is easy to separate in the next step, and since almost no water is used during polymerization, the water-soluble homopolymer is not attached to water. It has the advantage of being easily dissolved.

Further, since a small amount of the thermally polymerized homopolymer produced in the hydrophobic organic solvent becomes a fine powder precipitate, it can be easily filtered and separated.

In addition, a hydrophobic monomer that can be copolymerized with a water-soluble unsaturated monomer,
For example, it is also possible to use acrylates, methacrylates, styrene, etc. together with water-soluble unsaturated monomers.

Example 1 Approximately 0.4 g of polynosic cellulose fiber was placed in a 501 rL sealed tube, a predetermined amount of water shown in Table 1 was added, and after standing for approximately 20 minutes, 2 m13 of methacrylic acid as a water-soluble unsaturated monomer was added to the boiling point. Immerse in a solution dissolved in glue groin (hydrophobic organic solvent) at 105°C or higher, vacuum degas and replace with nitrogen in a system without adding a catalyst, shake at 85°C for 5 hours in a water bath, and graft polymerize. I did it.

After the reaction, the non-grafted methacrylic acid homopolymer was heated and dissolved and extracted three times using 200 times more methanol.

Completion of extraction of the homopolymer was confirmed by adding the extract into a large amount of benzene and checking that it did not become cloudy.

Example 2 Nylon filament (] 10d/28fil) 0.
Put 4g into a 50ml sealed tube, add 2ml of distilled water and let it stand for 30 minutes, then add 221ml of a solution consisting of 2ml of methacrylic acid and 20ml of toluene, vacuum degas, and replace with nitrogen at 85°C. , polymerization was carried out for 5 hours.

A methacrylic acid graft copolymerized nylon filament with a weight increase rate of 34% was obtained by the same post-treatment as in Example 1.

Example 3 Rayon thread (120d/26 fig) 2.02.9
1.5% distilled water containing 0.5% ammonium persulfate as catalyst
rrLl was placed in a 360 ml cider pin and soaked for 20 minutes, then a mixed solution of 15 mA of methacrylic acid dissolved in 100 mA of glue groin was added, and the atmosphere was replaced with nitrogen.
Polymerization was carried out at ℃ for 2 hours.

After polymerization, the nylon filament was filtered and boiled twice with 100 times methanol, and it was confirmed that there was no homopolymer in the methanol.The weight increase rate of the rayon thread remaining after the second extraction was 525%. So, the graft polymerization rate was 75.3%.
Met.

Example 4 30 wLA of distilled water containing 0.5% hydrogen peroxide was added to 461 g of benzalized polyvinyl alcohol fibers in a 3-l flask, and the mixture was left to stand for 15 minutes.
Take 3g of groin, add a mixed solution of 200ml of groin, and boil at 65°.
Polymerization was carried out at C for 1.5 hours.

The results are shown in Table 2.

Table 2 shows the weight increase rate of each fiber compared to other fibers when the same treatment as in Example 4 was performed.

It was found that when water-insoluble benzoyl peroxide was used as a catalyst instead of hydrogen peroxide used in Example 4, not only the weight increase rate but also the grafting efficiency decreased.

Example 5 5 g of polyacrylonitrile powder in a 1 liter flask,
Add 50 Tll of water and leave for 10 minutes, then add 3 liters of methacrylic acid.
A mixed solution of 0ml and 300mA of toluene was added, the air in the flask was replaced with nitrogen, and the reaction was carried out at 85°C for about 10 hours without stirring.

After 1 p, 28 g of mixed powder of graft copolymer and homopolymer was obtained.

The ammonium salt obtained by neutralizing this powder with ammonia showed a water absorption rate 110 times higher.

Example 6 A nylon film was slowly placed in a hot water bath containing 0.5% hydrogen peroxide and a 1:10 mixed solution bath (temperature 70°C) of methacrylic acid and groin (boiling point 105°C or higher) for 20 minutes each. A graft copolymer was obtained by passing through the mixture.

The weight increase rate was about 200%.

[Brief explanation of drawings]

FIG. 1 is a diagram of the principle of the conventional method, FIG. 2 is a diagram of the principle of the method of the present invention, and FIG. 3 is a graph showing the customization of the method of the present invention. A is a polymer compound base, B is a graft copolymer, C is a hydrophobic organic solvent, M is a water-soluble unsaturated monomer, and W is water.

Claims (1)

[Scope of Claims] 1 A polymerizable water-soluble unsaturated monomer is dissolved in a hydrophobic organic solvent and has a hydrophilic group such as a hydroxyl group, a carboxyl group, an acid amide group, or a nitrile group and absorbs water. A powder, fiber, or film-like substrate made of a polymeric compound is impregnated with water in a weight ratio of 5 to 10 to 1, and is immersed in the above solution to absorb the unsaturated monomer into the substrate. 1. A method for producing a graft copolymer, which comprises graft polymerization of a copolymer. 2. Claims characterized in that a radical catalyst such as hydrogen peroxide, potassium persulfate, etc., which is insoluble in the organic solvent and soluble in water, or a trace amount of a metal salt is added to the water with which the substrate is impregnated. A method for producing a graft copolymer according to item 1.