JPH04292606A - Production of vinylidene chloride-based resin particle - Google Patents

Abstract

PURPOSE:To enable ready production of the subject amorphous partly cross- linked vinylidene chloride-based resin particle having a relatively large particle size and a spherical shape in a high yield and to enable control of the particle size distribution thereof. CONSTITUTION:An amorphous vinylidene-based resin particle is used as a seed particle and swallen with copolymerizable unsaturated monomers mainly composed of vinylidene chloride, a cross-linking agent and a radical polymerization initiator in the presence of a low molecular weight polyvinyl alcohol and a surfactant having <=10 HLB to <=a limited swelling index. Aqueous suspension polymerization is subsequently carried out in the presence of a suspension stabilizer.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a relatively large particle size,
Furthermore, the present invention provides a method for easily producing amorphous vinylidene chloride resin particles having a spherical shape at a high yield, and a method for controlling the particle size distribution. The partially crosslinked amorphous vinylidene chloride resin particles obtained by the present invention are particularly useful as raw material resin particles for producing an excellent vinylidene chloride resin foam molded article by a bead foaming method.

0002

[Prior Art] A foamed molded article made of vinylidene chloride resin with excellent heat insulation properties and heat resistance using a bead foaming method was disclosed in JP-A-63.
-170434, a method for producing a partially crosslinked amorphous vinylidene chloride resin is disclosed in JP-A-63-12713.
listed in the number. Partially crosslinked amorphous vinylidene chloride resin particles used in the bead foaming method are difficult to manufacture by once melting and extrusion granulation, so they are directly manufactured by suspension polymerization. Particle size distribution depends on the application, but
In general, the narrower the better. If the particle size distribution is wide, the amount of blowing agent impregnated into the resin will vary from particle to particle, which may deteriorate the physical properties of the foam molded product, give the molded product a poor appearance, and reduce its commercial value. be.

[0003] In the normal suspension polymerization method, since there is a flow energy distribution at each position in the stirring tank and a statistical probability distribution exists in the collision of droplets, monomers and monomers are It is difficult to avoid the occurrence of distribution in the dispersion and coalescence of the droplets of the coalesced mixture, and therefore the particle size distribution of the resulting resin particles becomes wide. In the field of manufacturing technology for styrene resins, vinyl chloride resins, methyl methacrylic resins, crystalline vinylidene chloride resins, etc., methods for manufacturing these resins by suspension polymerization are well known. In particular, in the field of styrenic resin manufacturing technology where foam moldings are frequently produced by bead foaming, styrenic resin particles with a desired center diameter and narrow particle size distribution are produced by suspension polymerization. Many methods have been proposed for producing it with good yield.

[0004] These are methods characterized by suspension agents as described in Japanese Patent Publications No. 45-39459 and Japanese Patent Publication No. 46-21449, etc., and methods characterized by suspension agents as described in Japanese Patent Publication No. 57-10610 etc. A method characterized by proceeding to suspension polymerization after bulk polymerization, Japanese Patent Publication No. 40-824, Japanese Patent Publication No. 1987-57-
As described in No. 70111, etc., the method can be broadly divided into methods characterized by dissolving a styrene monomer in a styrenic resin and then subjecting it to suspension polymerization. However, in all of these methods, it is difficult to avoid the existence of a distribution in the dispersion and coalescence of droplets, and the resulting resin particles have a wide particle size distribution, which is not satisfactory. The method described in Japanese Patent Publication No. 46-2987, Japanese Patent Publication No. 49-19111, etc. is an improved method of these, in which uncrosslinked styrene resin particles of uniform particle size are dispersed in water, and the resin particles swell therein. This method was proposed as a method characterized by carrying out suspension polymerization by continuously or continuously supplying a monomer mainly composed of styrene in an amount that does not dissolve. However, in this method, it is necessary to maintain the monomer in the polymerization system at a weight ratio of monomer + polymer of about 0.6 or less. Continuous or continuous supply of turbidity stabilizer, etc. is required, and this method is complicated in terms of management and equipment, and is not necessarily a satisfactory method.

[0005] The present inventors have already developed a method for producing amorphous vinylidene chloride resin particles as described in Japanese Patent Application Laid-Open No. 2-1539.
In No. 11, we proposed a method to control particle size distribution. In this method, it was discovered that partially crosslinked vinylidene chloride resin is swollen by a copolymerizable unsaturated monomer mainly composed of vinylidene chloride in an amount of 1 to 20 times the weight of the resin at room temperature to around the polymerization temperature. , which is an epoch-making method that utilizes this. However, as the scale of the polymerization increases, this method may not be able to reproducibly disperse the swollen beads individually after adding the suspension stabilizer. Furthermore, it is difficult to set conditions for individual dispersion.

[0006]

[Problems to be Solved by the Invention] The problem to be solved by the present inventors is that in the production of amorphous vinylidene chloride resin particles, the particle size is relatively large and the shape is spherical.
The present invention provides a method for stably producing resin particles with a controlled particle size distribution and a small amount of aggregates at a high yield without depending on scale.

[0007]

[Means for Solving the Problems] As a result of intensive research to solve the above problems, the present inventors have developed amorphous vinylidene chloride resin particles, which are copolymerizable unsaturated particles mainly composed of vinylidene chloride. We have discovered that stable beads with less aggregation can be obtained by aqueous suspension polymerization after swelling with a monomer, a crosslinking agent, and a polymerization initiator, and based on these findings, we completed the present invention. It happened.

That is, the present invention uses amorphous vinylidene chloride resin particles as seed particles, and copolymerizable unsaturated monomers mainly consisting of vinylidene chloride in an amount such that the degree of swelling is equal to or less than the limit swelling degree of the seed particles. The seed is swollen in the presence of a low polymerization degree polyvinyl alcohol and a surfactant having an HLB of 10 or less, and is subjected to aqueous suspension polymerization in the presence of a suspension stabilizer. This is a method for producing vinylidene chloride resin particles.

The amorphous vinylidene chloride resin particles (hereinafter referred to as seed particles) used as seed particles in the present invention contain vinylidene chloride, one or more copolymerizable unsaturated monomers, and one or more copolymerizable unsaturated monomers. Contains a compound having two or more copolymerizable double bonds in the molecule (hereinafter referred to as a crosslinking agent). A preferred method for producing such seed particles includes initiating radical polymerization of 30 parts to 85 parts of vinylidene chloride, 15 parts to 70 parts of one or more copolymerizable unsaturated monomers, and a crosslinking agent. Examples include a method of carrying out aqueous suspension polymerization by adding a known suspension stabilizer in the presence of a polymer.

Examples of copolymerizable unsaturated monomers include vinyl chloride, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, acrylic acid, methacrylic acid, acrylic acid alkyl esters, and methacrylic acid alkyl esters. , glycidyl acrylate,
Glycidyl methacrylate, N-phenylmaleimide,
Known monomers such as N-substituted maleimides such as N-cyclohexylmaleimide and N-2chlorophenylmaleimide can be mentioned.

Examples of the crosslinking agent include divinylbenzene, diacrylate esters of diols such as ethylene glycol, propylene glycol, 1.3 butylene glycol, 1.6 hexanediol, and neopentyl glycol;
Known copolymerizable crosslinking agents such as dimethacrylic acid esters can be mentioned. Since the gel fraction (described below) of the seed particles can be adjusted by adjusting the amount of the crosslinking agent, the amount of the crosslinking agent can be determined so that the gel fraction of the seed particles has a desired value. Known radical polymerization initiators and suspension polymerization stabilizers can be used.

[0012] The seed particles used in the present invention must have a limit swelling degree (hereinafter referred to as LSI) defined below or less. The seed particles need to be amorphous because crystallinity results in low LSI and is not preferred for the present invention. Generally, a resin containing 85% by weight or less of structural units derived from vinylidene chloride is amorphous. Amorphous means that it does not exhibit an endothermic peak due to crystal melting in differential thermal analysis (DSC), or does not exhibit a clear diffraction peak due to crystals in wide-angle X-ray diffraction. If the gel fraction exceeds 85%, the LSI will be low, which is undesirable, so it is preferably 85% or less.

[0013] The gel fraction refers to the ratio of 1 to 2 g of resin to 50
After immersing in twice the amount of tetrahydrofuran at 40°C for 1 hour with stirring, the soluble and insoluble components were separated by filtration, and the tetrahydrofuran was removed by evaporation. From the weight of the obtained tetrahydrofuran insoluble component, the value was determined by the following formula. It is. Gel fraction (%) = (weight of insoluble matter) x 100/(weight of added resin particles) In addition, the limit swelling degree (LSI) is the amount of monomer used in polymerization of 2 to 5 g of resin particles in excess. After soaking in a mixed solution of body composition for 1 hour under stirring at room temperature, it was filtered through a 200 mesh wire mesh.
The monomer remaining on the wire mesh was determined from the weight of the swollen resin particles using the following formula. Limit swelling degree (LSI) = (weight of resin particles in a state where the monomer is swollen) / (weight of resin particles before swelling) The monomers used in the production method of the present invention (hereinafter also referred to as seed polymerization) are: , radically polymerizable unsaturated monomers can be used,
In particular, the amount of vinylidene chloride is preferably 30 parts or more and 85 parts or less, and the amount of one or more copolymerizable unsaturated monomers is preferably 15 parts or more and 70 parts or less of mixed monomers. In the present invention, parts are expressed as a value based on 100 parts of the total weight of vinylidene chloride and one or more copolymerizable unsaturated monomers used.

If vinylidene chloride is less than 30 parts, the original properties of the resulting resin such as flame retardancy, gas barrier properties, and chemical resistance will deteriorate, and if it exceeds 85 parts, the resin will develop crystallinity and bead foaming will occur. The impregnability of the blowing agent decreases. As the copolymerizable unsaturated monomer and crosslinking agent used in the seed polymerization, the known ones mentioned in the explanation of the seed particles can be used.

As the radical polymerization initiator, known oil-based polymerization initiators such as lauryl peroxide and benzoyl peroxide can be used. As suspension stabilizers, hydroxypropyl methyl cellulose, partially saponified polyvinyl alcohol (polymerization degree of 1000 or more, saponification degree of 98
It is preferably less than mol%. A known water-soluble suspension stabilizer such as PVA (hereinafter abbreviated as PVA) can be used.

[0016] The low degree of polymerization polyvinyl alcohol added to the seed polymerization has a degree of polymerization of 500 or less and a degree of saponification of 95 mol%.
The following is required. Further, it is necessary that the surfactant added in combination has an HLB of 10 or less. Low polymerization degree polyvinyl alcohol and surfactant are first adsorbed on the surface of the unsaturated monomer, and when they are absorbed by the seed particles, they are adsorbed on the surface of the swollen particles, which has the effect of mitigating aggregation between the swollen particles. be. If the degree of polymerization of low-polymerization degree polyvinyl alcohol exceeds 500 or the surface active HLB exceeds 10, unsaturated monomers tend to be stabilized as oil droplets in the aqueous phase, which prevents them from swelling into seed particles. Generates fine particles. A similar effect is obtained when the amount added is large. Also,
If the amount added is small, the effect of reducing aggregated particles will be reduced. Therefore, the amount of low polymerization degree polyvinyl alcohol added is preferably 0.5 part to 0.001 part, and more preferably 0.05 part to 0.005 part. The amount of surfactant added is preferably 0.5 part to 0.001 part, more preferably 0.2 part to 0.01 part.

[0017] If low polymerization degree polyvinyl alcohol and a surfactant are not added, the swollen particles will strongly fuse with each other, so even if a suspension stabilizer is added, it will be difficult to disperse them as individual swollen particles. If the reaction continues as it is, several tens of percent of the particles will be generated as two or several aggregated particles. The surfactants used include polyoxyethylene glycols such as polyoxyethylene monooleate (7.9), sorbitan monolaurate (8.6), sorbitan monopalmitate (6.7), and sorbitan monooleate (7.9). Stearate (
4.7), sorbitan esters such as sorbitan monooleate (4.3), sorbitan sesquioleate (3.7), sorbitan trioleate (1.8), phosphate esters (6.9), diesters, etc. A phosphorus-based surfactant is most suitable. The value in parentheses is the manufacturer's HLB value. Note that HLB indicates the balance between hydrophilic groups and lipophilic groups of a surfactant.

Furthermore, when polyvinyl alcohol with a low degree of polymerization is used, swelling can proceed stably even in areas where the gel fraction is low. According to the seed polymerization of the present invention, the particle size distribution of the produced particles is determined by the particle size distribution of the seed particles and the degree of swelling (hereinafter referred to as
SI), the type and amount of suspension stabilizer,
The intensity of stirring is virtually unaffected.

[0019] In seed polymerization, SI is preferably less than LSI. This is because if it is less than LSI, substantially the entire amount of the swollen monomer will be polymerized within the seed particle. The average particle size can be approximately 1/3 (SI) times that of the seed particles. The particle size distribution is also (SI) 1/3
can be obtained by moving parallel to . When the LSI is exceeded, monomers that do not swell are present in the seed particles, which become fine particles through polymerization, making it impossible to control both the average particle size and particle size distribution.

The degree of swelling (SI) is a value determined from the weight of the seed particles (WS) and the weight of the monomer (WM) used in the seed polymerization method using the following formula. Swelling degree (SI) = (WS + WM ) / WS Swelling of the monomer, crosslinking agent, and radical polymerization initiator to the seed particles occurs when the seed particles are hydrated in the presence of low polymerization degree polyvinyl alcohol and a surfactant. This can be achieved by stirring and mixing the monomer, crosslinking agent, and radical polymerization initiator at a temperature below the polymerization initiation temperature. Next, by adding a suspension stabilizer and stirring, the seed particles swollen with monomers etc. are individually dispersed. Thereafter, desired resin particles can be obtained by raising the temperature to a predetermined temperature and conducting a reaction.

As explained above, in other words, the present invention is a polymerization method having a mechanism in which the monomer that causes the seed particles to swell and expand is substantially polymerized within the seed particles, and the particle size of the seed particles and the SI This is a polymerization method in which the particle size distribution can be controlled by selecting . Therefore, the type and amount of suspending agent,
The viscosity of the mixture of monomer and polymer, addition of a small amount of monomer, etc.
This polymerization method is completely different from conventional particle size control methods.

Furthermore, according to the method of the present invention, resin particles having a non-standard particle size can be used after changing to a particle size within the standard. In addition, when using the obtained particles in foam beads,
By selecting a surfactant, it is possible to improve the fluidity and fusion properties of beads.

[0023]

EXAMPLES The present invention will now be explained in more detail with reference to examples, but the invention is not limited to these examples. In addition, parts in Examples represent parts by weight. In addition, the particle size is displayed as follows. (Example) 0.1mm to 0.2mm: 0.1mm or more, 0.1mm to 0.2mm: 0.1mm or more, 0.
Less than 2mm

[0024]

[Examples 1 to 3] A reaction vessel was charged with a solution in which PVA was previously dissolved as a suspending agent in 100 parts of water, and then 7 parts of N-phenylmaleimide was mixed with 20 parts of acrylonitrile, 23 parts of styrene, and 1.6 hexanediol. Diacrylate 0.0
7 parts of the mixed solution, and then add 50 parts of vinylidene chloride.
0.8 parts of lauryl peroxide was charged as a radical initiator. After nitrogen replacement,
Stirring was started, the temperature was raised to 60° C., and the resulting resin particles were reacted for 26.5 hours, and the resulting resin particles were filtered, washed with water, and then dried. The residual monomer content in the obtained resin particles was all 0.5% or less, and the polymerization rate was 98% or more.

The gel fraction and critical swelling degree of the resin particles having a particle size of 0.1 to 0.3 mm obtained by sieving were as follows.
Content Gel fraction Limit swelling degree 0.1mm to 0.2mm: 31%
41% 11 0.2m
m~0.3mm: 69% 43%
11 Next, add a polymerization degree of 10 to 100 parts of water.
0, 0.005 part of low polymerization degree polyvinyl alcohol with saponification degree of 50 to 70 mol% was dissolved, and 20 parts of the above resin particles of 0.1 to 0.3 mm as seed particles and each interface shown in Table 1 were dissolved. Charge 0.05 parts of an activator into a reaction vessel, and add 7 parts of N-phenylmaleimide and 2 parts of acrylonitrile.
0 parts, 23 parts of styrene, 50 parts of vinylidene chloride, 1.6
A monomer mixture containing 0.065 parts of hexanediol diacrylate and 0.8 parts of lauryl peroxide were charged, followed by stirring for 1 hour. The degree of swelling is 6.

Next, an aqueous solution of 0.3 parts of PVA dissolved in 14 parts of water was added, and after stirring for 1 hour, the temperature was raised to 60°C.
．． The reaction took place for 5 hours. The results are shown in Table 1. HLB1.8,
4.3, 8.6, the content of less than 0.2 mm is 2-3%
showed a good value. Further, no aggregates were observed.

[0027]

[Example 4] Resin particles having a particle size of 0.2 to 0.3 mm obtained by sieving in the same manner as in Examples 1 to 3 were used as seed particles. Next, 20 parts of the above seed particles, 0.005 part of low polymerization degree polyvinyl alcohol (polymerization degree 100, saponification degree 50-70 mol%) and 0.05 part of sorbitan oleate as a surfactant were added to 100 parts of water. Prepared in the same manner as Examples 1 to 3, and further added 5 parts of N-phenylmaleimide, 30 parts of acrylonitrile, 15 parts of styrene, and 50 parts of vinylidene chloride.
parts, 1.6 hexanediol diacrylate 0.065
1 part of monomer mixture and 0.8 part of lauryl peroxide were added, and the mixture was stirred for 1 hour. The degree of swelling is 6.

Next, an aqueous solution of 0.3 parts of PVA dissolved in 14 parts of water was added, and after stirring for 1 hour, the temperature was raised to 60°C and the mixture was heated to 26°C.
．． The reaction took place for 5 hours. The results are shown in Table 2. The limit swelling degree is 1
It was 2. The content of particles less than 0.3 mm was 4%, and the content of aggregates was 0%, which were good values.

[0029]

[Example 5] A solution of 0.2 parts of hydroxypropyl methylcellulose as a suspension stabilizer dissolved in 120 parts of water was charged into a reaction vessel, and further 50 parts of methyl methacrylate,
Vinylidene chloride 50 parts, divinylbenzene 0.04 parts,
A mixed solution of 0.2 part of diisopropyl peroxydicarbonate was charged. After purging with nitrogen, stirring was started and the temperature was raised to 40°C, followed by reaction for 24 hours, and the resulting particles were separated by filtration, washed with water, and dried. The amount of residual monomer in the obtained resin particles was 0.5% or less. The polymerization rate was 98% or more. The gel fraction of the resin with a particle size of 0.2 to 0.4 mm obtained by sieving is 47%.
Met.

The obtained resin particles having a particle size of 0.2 to 0.4 mm were used as seed particles. Next, 100 parts of water and 20 parts of the above seed particles were charged into a reaction vessel in the same manner as in Example 4, and 50 parts of vinylidene chloride and 20 parts of acrylonitrile were added.
In the same manner as in Example 4, a monomer mixture consisting of 30 parts of styrene, 0.02 parts of divinylbenzene, and 0.8 parts of uralyl peroxide was charged. The degree of swelling is 6. The results are shown in Table 2. The limit swelling degree was 14. 0.3m
The content of less than m was 4%, and the content of aggregates was 2%, which was a good value.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

Effects of the Invention The present invention provides a method for easily producing partially crosslinked amorphous vinylidene chloride resin particles having a relatively large particle size and a spherical shape in a high yield, and also controls the particle size distribution. The present invention proposes a method to do this, and is useful as raw material resin particles for producing foamed molded products.

Claims (1)

[Claims] [Claim 1] A copolymerizable unsaturated monomer mainly composed of vinylidene chloride, a crosslinking agent, and an amount of amorphous vinylidene chloride-based resin particles as seed particles, the degree of swelling being equal to or less than the limit swelling degree of the sheet particles. and a radical polymerization initiator are swollen into the sheet in the presence of low polymerization degree polyvinyl alcohol and a surfactant having an HLB of 10 or less, and aqueous suspension polymerization is carried out in the presence of a suspension stabilizer. A method for producing partially crosslinked amorphous vinylidene chloride resin particles.