JP2012072257A - Hollow vinyl chloride resin particles, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide hollow PVC particles having a sharp particle size distribution and a porosity of 38 volume% or more.SOLUTION: The hollow vinyl chloride resin particles have: a passing ratio of a 60 mesh sieve of 95 wt% or more; a passing ratio of a 200 mesh sieve of 5 wt% or less; and the porosity of 38 volume% or more. In the method for producing the hollow vinyl chloride resin particles, they are produced by suspension polymerization in a system including monomer components including vinyl chloride as a principal component and a polyfunctional monomer, a polymerization initiator, a dispersant, and an emulsifying agent. In this process, as the emulsifying agent component, 10,000-20,000 ppm of higher fatty acid ester is added based on the all monomers. The particles can be produced in a high yield (a polymerization yield: 80% or more) without producing a scale.

Description

  The present invention provides a high yield (polymerization yield: 80%) of hollow vinyl chloride resin particles having high voids (porosity: 38% by volume or more) and sharp particle size distribution without generating scale. % Or more).

Conventionally, vinyl chloride resin (hereinafter abbreviated as PVC) has excellent physical and chemical properties and is used in a wide range of molded products because it is cheaper than other resins.
However, PVC has a large specific gravity of 1.4 and is disadvantageous in that it is heavier than other resins, and various attempts have been made to reduce the weight.
In order to lower the specific gravity, a method of introducing voids into the resin is generally taken.
Examples of methods aimed at increasing the porosity in PVC include a method of adding a higher fatty acid ester as an emulsifier (Patent Document 1) and a method of forcibly discharging a vinyl chloride monomer component during polymerization (Patent Document 2).

JP-A-11-171905 JP-A-11-228606

However, each of these conventional inventions has the following problems.
The invention described in Patent Document 1 aims at high voids and a high polymerization yield, and improves voids in the PVC particles by using an emulsifier.
However, because of the stability of the particles during polymerization, the allowable upper limit of the emulsifier is as small as 5,000 ppm, and scales are generated when the allowable upper limit is exceeded, so the void ratio of the resulting hollow PVC particles is also 36 volumes. % Is the limit, and a high porosity has not been achieved.

The invention described in Patent Document 2 is a method for forcibly discharging 5 to 20% of a raw material vinyl chloride monomer in the weight ratio of vinyl chloride monomer remaining in the reaction system at the time of polymerization, thereby scaling to the inner wall of the polymerization vessel. An object of the present invention is to obtain PVC particles without a skin layer that suppress adhesion and show a sharp particle size distribution with high voids.
In the method of Patent Document 1, the voids between the primary particles are increased, whereas in the method of Patent Document 2, the voids in the primary particles are further increased.
Since Patent Documents 1 and 2 are different in the place where voids are formed, Patent Document 2 is expected to have an additive effect, but it is forcibly discharged up to 20% of the vinyl chloride monomer remaining during the polymerization. Therefore, when the particle skeleton is formed, the amount of residual monomer is small, and the void ratio of the hollow PVC particles obtained as confirmed in the examples is limited to 35% by volume. Remains in trace amounts.

Under such circumstances, an object of the present invention is to provide hollow PVC particles having a sharp particle size distribution and a porosity of 38% by volume or more.

  As a result of intensive studies to solve the above problems, the present inventors have added a higher fatty acid ester, which is an emulsifier, in the presence of a polyfunctional monomer in the presence of a polyfunctional monomer at 10,000 to 20,000 ppm based on the total monomer. The inventors have found that the above-mentioned problems can be achieved, and have come to accomplish the present invention based on this finding.

That is, in the first invention of the present invention, the hollow chlorination in which the passing rate of the 60 mesh sieve is 95% by weight or more, the passing rate of the 200 mesh sieve is 5% by weight or less, and the porosity is 38% by volume or more. Vinyl resin particles are shown.
10% or more higher than that of the prior art, which shows a sharp particle size distribution that gives good molding responsiveness of the obtained PVC particles and also reduces the specific gravity of the molded product using the particles. It has a porosity.
When the porosity is less than 38% by volume, the effect of weight reduction using the particles is reduced, which is not preferable.

The sieve shown here refers to a JIS test sieve.
The particle size distribution is determined by the passing rate of the sieve, and the obtained polyvinyl chloride particles are fractionated according to JIS Z 8801, and the weight of the passing amount is measured to determine the passing rate and the particle size of each sieve. Distribution was calculated.
The sharpness of the particle size distribution shown here determines that the particle size distribution is sharp if the 60 mesh passage in the particle size distribution is 95% by weight or more and the 200 mesh passage is 5% by weight or less.

The porosity shown here represents the volume of the hollow portion in the entire volume of the hollow PVC particles expressed as a percentage (%). For example, the condition of the enclosed mercury pressure of 2000 kg / cm 2 using an AMCO Porosimeter 2000, etc. And can be measured by the following formula.
Porosity (%) = (V2 / V1) × 100
V1: Bulk volume of hollow particles before mercury is injected. V2: Hollow particle pore volume at an enclosed mercury pressure of 2000 kg / cm @ 2.

According to the second invention of the present invention, a vinyl chloride resin is obtained by suspension polymerization in a system comprising a monomer component containing vinyl chloride as a main component and a polyfunctional monomer, and a polymerization initiator, a dispersant and an emulsifier. When particles are produced, a higher fatty acid ester is used as the emulsifier component, and the same component is added to 10,000 to 20,000 ppm with respect to all monomers, so that the polymerization yield of the hollow PVC particles can be reduced without generating scale. It is possible to obtain the particles of the first invention while ensuring a rate: 80% or more.

The polyfunctional monomer shown here is a monomer having two or more functional groups capable of reacting with a vinyl group in the molecule.
There exists an effect | action which raises the bridge | crosslinking degree of PVC, and since PVC particle | grains are hard and stabilized, there exists an effect which prevents the compression resistance strength improvement, the sharpening of a particle size distribution, and scale adhesion.
For example, di (meth) acrylate such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane di (meth) acrylate, etc. (Meth) acrylate; tri (meth) acrylate such as trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate; pentaerythritol tetra (meth) acrylate, Di or tria such as dipentaerystol hexa (meth) acrylate, diallyl phthalate, diallyl malate, diallyl fumarate, diallyl succinate, triallyl isocyanurate Le compounds; divinyl benzene, divinyl compounds such as butadiene and the like.

These may be used alone or in combination of two or more.
Although these compounding quantities are not specifically limited, A preferable minimum is 0.1 weight% and a more preferable minimum is 0.3 weight%.
If it is less than 0.1% by weight, the resulting hollow PVC particles have insufficient compressive strength, which may cause broadening of the particle size distribution and increase in scale.
On the other hand, the preferable upper limit is 50% by weight, more preferably 30% by weight or less.
As the amount of polyfunctional monomer increases, the amount of vinyl chloride monomer relatively decreases, and the amount of vinyl chloride component that forms voids with the emulsifier decreases, so the amount of voids decreases, and high voids can be achieved. Absent.
Moreover, there exists a possibility that the characteristics as vinyl chloride, such as a flame retardance, cannot be exhibited.

The polymerization initiator shown here decomposes upon receipt of external energy such as heat and light to generate radicals that are the starting point of polymerization, and is soluble in the monomer component containing the above-mentioned vinyl chloride and polyfunctional monomer. It is oil-soluble.
In general, known radical polymerization initiators and the like used for polymerization of PVC are preferably used.
The radical polymerization initiator is not particularly limited, and examples thereof include t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-hexylperoxypivalate, and α-cumylperoxyneodecano. Perester compounds such as diates, t-hexyl neohexanoate, 2,4,4-trimethylpentyl-2-peroxy-2-neodecanoate; diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di- Percarbonate compounds such as 2-ethoxyethyl peroxydicarbonate and dimethoxyisopropylperoxydicarbonate; decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide Peroxide compounds such as 2,4-dichlorobenzoyl peroxide, p-menthane hydroperoxide, 3,5,5-trimethylhexanoyl peroxide, isobutyl peroxide; α, α′-azobisisobutyronitrile, α, Examples thereof include azo compounds such as α′-azobis (dimethylvaleronitrile) and α, α′-azobis (4-methoxy-2,4-dimethylvaleronitrile).

These may be used alone or in combination of two or more.
Although these compounding quantities are not specifically limited, Generally it is 0.001-2 weight part with respect to 100 weight part of monomer components containing a vinyl chloride and a polyfunctional monomer.

The dispersant shown here is a surfactant having a high physical adsorptivity.
Since it has high adsorptivity, it has the effect of promoting the dispersion of the monomer droplets and making the particles uniform.
For use in suspension polymerization, water-soluble ones are used, for example, partially saponified polyvinyl alcohol, cellulose derivatives such as methylcellulose, silica, calcium phosphate, magnesium hydroxide, aluminum hydroxide, ferric hydroxide, barium sulfate. , Calcium sulfate, sodium sulfate, calcium oxalate, calcium carbonate, barium carbonate, magnesium carbonate and the like.

These may be used alone or in combination of two or more.
Although these compounding quantities are not specifically limited, It is preferable to use in the ratio of 0.1 weight part-20 weight part with respect to 100 weight part of monomer components containing the said vinyl chloride and a polyfunctional monomer.

The emulsifier shown here is a surfactant having a function of reducing the interfacial tension between the monomer and the solvent.
The higher the function of lowering the surface active tension, the smaller the primary particles can be made in the monomer droplet.
When the primary particles are vigorously dispersed and united during polymerization during polymerization, the primary particles can be coalesced so as not to be densely packed together, and voids inside the particles can be increased.
Examples thereof include sorbitan monolaurate sorbitan monomyristate, sorbitan monopalmitate, sorbitan monostearate sorbitan distearate sorbitan tristearate and other sorbitan saturated higher fatty acid esters, and unsaturated higher fatty acid esters.

These may be used alone or in combination of two or more.
Although these compounding quantities are not specifically limited, Addition of 10,000-20,000 ppm is preferable with respect to the monomer component containing the said vinyl chloride and a polyfunctional monomer.
If it is less than 10,000 ppm, the improvement of the porosity is low and it is impossible to achieve a high yield. If it exceeds 20,000 ppm, the oil droplets of the monomer components become unstable, and the resin scale adheres to the inner wall of the polymerization vessel. There is a fear.

In Patent Documents 1 and 2, the addition of higher fatty acid esters of 10,000 ppm or more was supposed to deteriorate the particle size distribution and increase the scale. In the present invention, by using a polyfunctional monomer in combination, Since the particles harden, it becomes difficult to unite even if the particles collide during polymerization, and even if the amount of the higher fatty acid ester is increased, a sharp particle size distribution and scale adhesion can be prevented.

The amount of scale adhering to the inner wall of the polymerization vessel shown here is to measure the weight of the non-passing amount by separating the obtained PVC particles using a 19-mesh sieve according to JIS Z8801.
If the amount of scale adhesion to the polymerization inner wall is large, there is a risk that the polymer existing as particles will decrease, such as blocking due to coalescence of particles.
As an evaluation of the scale amount, it is measured as a proportion of the scale in the total yield, and less than 5% by weight is represented by ◯, and 5% by weight or more is represented by x.

The suspension polymerization shown here refers to a monomer component containing the above vinyl chloride and a polyfunctional monomer, and a water-soluble polymer compound having a functional group that can be crosslinked with the monomer component by a polymerization initiator and a crosslinking agent. The polymerization is not particularly limited as long as it is a method for preparing a polymerization in a suspension state in a polar medium containing, for example, a monomer solution in which a monomer component and a polymerization initiator are dissolved is prepared in advance, and this is dissolved in the above water-soluble solution. For example, a method of adding to a polar medium containing a conductive polymer compound and dispersing in oil droplets by stirring. Since the particle diameter of the obtained hollow PVC particles depends on the oil droplet diameter in the suspension, it can be easily controlled by the type and amount of the dispersion stabilizer, the stirring method and strength, and the like.

The temperature at which the monomer component is polymerized is appropriately determined depending on the composition and molecular weight of the monomer component to be used, the type and amount of the polymerization initiator, etc., but is usually in the range of 30 to 70 ° C.

After the completion of the polymerization reaction, for example, the target hollow PVC particles can be obtained by heating the resin with steam, hot air or the like, or placing the resin under reduced pressure conditions.

The polymerization yield shown here represents how much all monomers charged into the polymerization vessel have been polymerized, and is represented by the following formula.
Polymerization yield (%) = Polymer weight (g) obtained by polymerization / Total monomer weight (g) charged into the polymerization vessel

As shown in Tables 1 and 2, according to the present invention, the formation of PVC particles while ensuring a polymerization yield of the hollow PVC particles: 80% or more without generating a scale in order to increase the yield. Hollow PVC particles having a sharp particle size distribution with good responsiveness and a porosity of 38% by volume or more can be obtained.

An embodiment of the present invention will be described based on Example 1 below.
A schematic flow of the reaction process is shown in FIG.

Example 1: Production of vinyl chloride-based hollow particles In a 25 L pressure-resistant polymerization vessel equipped with a stirring blade inside and a jacket for heating and cooling on the outer periphery,
Ion-exchanged water: When 8.78 kg was charged,
Multifunctional monomer: Trimethylolpropane trimethacrylate: 0.92 kg,
Dispersant: Polyvinyl alcohol is added in the form of a 10% aqueous solution as a polyvinyl alcohol component so as to be 1.5 parts by weight with respect to 100 parts by weight of the total of vinyl chloride monomer and polyfunctional monomer,
Emulsifier: Add sorbitan fatty acid ester in the form of a 16% aqueous solution as a sorbitan fatty acid ester component so that the total amount of vinyl chloride monomer and polyfunctional monomer is 10,000 ppm.
Oil-soluble radical initiator: di-sec butyl peroxydicarbonate: 3.7 g and α-cumyl peroxyneodecanoate: 5.5 g
Was introduced.
After the polymerization vessel was sealed and the air inside the vessel was deaerated, 2.76 kg of vinyl chloride monomer was injected, and then stirring was started and suspended for 10 minutes.
Thereafter, the temperature was raised to 54 ° C. with stirring, and water suspension polymerization was performed while maintaining the temperature in the polymerization vessel at 54 ° C.
When the internal pressure dropped to 0.4 MPa, cooling water was passed through the jacket to 30 ° C., and then the polymerization slurry was taken out, dehydrated with a dehydrator, and vacuum dried to obtain porous hollow resin particles. The polymerization yield was 80%.

Example 2: Production of vinyl chloride hollow particles Emulsifier: The same procedure as in Example 1 except that the amount of sorbitan fatty acid ester was changed to 20,000 ppm.

Comparative Example 1: Production of vinyl chloride hollow particles The same procedure as in Example 1 was conducted except that the amount of emulsifier: sorbitan fatty acid ester was changed to 5,000 ppm.

Comparative Example 2: Production of vinyl chloride-based hollow particles The same procedure as in Example 1 was conducted except that the amount of emulsifier: sorbitan fatty acid ester was changed to 25,000 ppm.

Comparative Example 3: Production of vinyl chloride hollow particles based on Example 1 in Japanese Patent Application Laid-Open No. 11-171905 In a polymerizer (pressure autoclave) having an internal volume of about 100 liters,
Add 45 kg of deionized water, and, with respect to the weight of the vinyl chloride monomer component,
350 ppm of partially saponified polyvinyl acetate having a mercapto group at the molecular chain end (saponification degree 75 mol%, average polymerization degree 500),
Sorbitan monolaurate (HLB = 8.6) 1,000 ppm,
1,000 ppm of lauric acid,
Polyacrylamide (average molecular weight 12 million to 14 million, 51 cP / 0.1% aqueous solution) 100 ppm,
t-Butylperoxyneodecanoate 500ppm
Was introduced.
Next, after degassing the inside of the polymerization vessel to 40 mmHg, 45 kg of a vinyl chloride monomer component was charged and stirring was started. The polymerization temperature was 57 ° C., and this temperature was maintained until the polymerization was completed.
When the polymerization conversion rate reached 95%, the reaction was terminated, and after recovering the unreacted vinyl chloride monomer component in the polymerization vessel, the polymer was taken out of the system in a slurry state, dehydrated and dried to obtain the desired PVC. .

Comparative Example 4: Production of vinyl chloride hollow particles based on Example 1 in JP-A-11-228606, into a polymerizer (pressure-resistant autoclave) having an internal volume of about 100 liters, 45 kg of deionized water, To the weight of the vinyl chloride monomer component
Partially saponified polyvinyl acetate (saponification degree 72 mol%, average polymerization degree 700) 500 ppm,
Sorbitan monolaurate (HLB = 8.6) 1,400 ppm,
1,400 ppm lauric acid,
Polyethylene oxide (average molecular weight, 4.3 million to 4.8 million, 12 cP / 0.1% aqueous solution) 100 ppm,
t-Butylperoxyneodecanoate 500ppm
Was introduced.
Next, after degassing the inside of the polymerization vessel to 40 mmHg, 45 kg of a vinyl chloride monomer component was charged and stirring was started. The polymerization temperature was 57 ° C., and this temperature was maintained until the polymerization was completed.
After the polymerization temperature reaches a constant temperature, when about 31 kg of the vinyl monomer component is consumed by polymerization (monomer / aqueous medium = about 0.3), about 1.5 kg of the vinyl chloride monomer component (residual monomer in the polymerization vessel) (Corresponding to about 0.1 by weight with respect to 1) was removed from the system by exhaust gas operation and led to a vinyl chloride monomer component recovery device. The polymerization was further continued, and the reaction was terminated when the polymerization conversion rate reached 95%. After recovering the unreacted vinyl chloride monomer component in the polymerization vessel, the polymer was taken out of the system in a slurry state, dehydrated and dried, The desired PVC was obtained.

Comparative Example 5:
The same procedure as in Example 1 was carried out except that no polyfunctional monomer was added.

The results are shown in Tables 1 and 2.

It is an example of the reaction process schematic flow of this invention.

Claims (2)

Hollow vinyl chloride resin particles in which the passing rate of a 60 mesh sieve is 95% by weight or more, the passing rate of a 200 mesh sieve is 5% by weight or less, and the porosity is 38% by volume or more.
  When producing vinyl chloride resin particles by suspension polymerization in a system containing a monomer component containing vinyl chloride as a main component and a polyfunctional monomer, and a polymerization initiator, a dispersant and an emulsifier, the emulsifier component The method for producing hollow vinyl chloride resin particles according to claim 1, wherein the higher fatty acid ester is added in an amount of 10,000 to 20,000 ppm based on all monomers.

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