JPH10292016A - Vinyl chloride copolymer particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinyl chloride copolymer particle having excellent storage stability in the state of a plastisol or an organosol. SOLUTION: This vinyl chloride copolymer particle is prepared by copolymerizing vinyl chloride monomer M1 and another monomer M2 which can copolymerize with M1 with a copolymerization reactivity ratio r2 of 1 or more, and has a particle structure composed of an outer shell of a copolymer containing a small amount of the monomer M2 , or a homopolymer of vinyl chloride and an inner layer, formed inside the outer shell, containing the monomer M2 in a major amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vinyl chloride copolymer particles having excellent storage stability (having little change in viscosity) when formed into a plastisol or organosol.

[0002]

2. Description of the Related Art Vinyl chloride-based copolymer particles for so-called pastes, which are converted into plastisols or organosols, are a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith (hereinafter referred to as a vinyl chloride monomer mixture). ) Is emulsion-polymerized using a water-soluble polymerization initiator, or an oil-soluble polymerization initiator that is soluble in a vinyl chloride-based monomer mixture is added, and this is mechanically dispersed uniformly and finely in water. It is manufactured by a fine suspension polymerization method in which polymerization is carried out after (homogenization treatment). However, these methods usually involve adding a copolymerizable monomer (comonomer) to a polymerization system all at once before starting polymerization. Is often produced by the same method as that for producing vinyl chloride homopolymer. This is a comonomer,
Mainly copolymerization reactivity ratio r ₂ with vinyl chloride such as vinyl acetate is by also that were of less than 1.

[0003] The vinyl chloride-based copolymer particles for paste obtained in this manner are prepared by adding, for example, a plasticizer, a diluent, a stabilizer, and a pyrolytic organic foaming agent and a foaming agent depending on the use to the copolymer. Flooring, wallpaper, ceiling covering, leather, sealing, manufactured by mixing or kneading a foaming aid called "kicker" that lowers the decomposition temperature of the material, and then heating and gelling it through a so-called "plastisol" state. It is used in large quantities for materials and other applications.

[0004] These vinyl chloride-based copolymer particles generally have a characteristic of better melting property than vinyl chloride homopolymer particles, and are often used for applications utilizing this characteristic. Although the meltability is good, when this is mixed with a plasticizer to form a plastisol, the storage stability of the sol is inferior, so that the sol viscosity increases remarkably with time, and the handleability decreases, and further, as a sol, There was a problem that it could not be used. This tendency is the same in an organosol using a solvent as a dispersion medium.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide a vinyl chloride copolymer having excellent storage stability when formed into a plastisol or organosol. To provide coalesced particles.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have produced vinyl chloride copolymer particles having good storage stability in the form of a plastisol or organosol (hereinafter simply referred to as a plastisol) free from the above-mentioned disadvantages. As a result of intensive studies, the copolymerization reactivity ratio of M ₂ when the vinyl chloride monomer is defined as monomer 1 (M ₁ ) and the copolymerizable monomer is defined as monomer 2 (M ₂ ) is 1 or more. It has been found that copolymer particles obtained by adding the compound under specific conditions can achieve the object of the present invention without impairing properties such as meltability, and have completed the present invention.

However, the gist of the present invention is as follows.
A vinyl chloride-based copolymer particle produced by copolymerizing a vinyl chloride monomer M ₁ and a monomer M ₂ copolymerizable therewith and having a copolymerization reactivity ratio r ₂ of 1 or more. So,
The outer shell of the copolymer particles is a copolymer containing a small amount of the monomer M ₂ or a vinyl chloride homopolymer, and a layer of the monomer M ₂ rich copolymer is provided inside the outer shell. Are formed in the vinyl chloride copolymer particles having a particle structure formed by

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The vinyl chloride copolymer particles of the present invention are produced by the above-mentioned emulsion polymerization method or fine suspension polymerization method. The monomer (M ₂ ) used for the copolymerization is
For example, unsaturated nitriles such as acrylonitrile,
Methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate,
2-hydroxypropyl acrylate, methacrylic acid-
Acrylic acid such as 2-hydroxypropyl, esters of methacrylic acid, dimethyl itaconate, diethyl itaconate, diisopropyl itaconate, itaconic esters such as dioctyl itaconate, vinylidene chloride, aromatic vinyl compound, etc. Copolymerization reactivity ratio r ₂ ≧ 1
And a mixture of one or more of these monomers.

Monomer M copolymerizable with vinyl chloride_TwoIs r
_TwoLimited to the above if the condition of ≧ 1 is satisfied
But not particularly acrylates and methacrylates.
Lulic esters are preferred in view of the effect of modifying the melting property and the like.
Further, a copolymerizable monomer M _TwoContent of the copolymer
30% by weight or less, preferably in the range of 1 to 20% by weight.
It is preferably in the range of 2 to 10% by weight.

In the polymerization method of the present invention, as a polymerization initiator, for example, a water-soluble peroxide such as persulfate (sodium salt, potassium salt, ammonium salt, etc.), hydrogen peroxide or the like, or sodium sulfite, sulfite, A water-soluble redox initiator comprising a reducing agent such as ammonium sulfate, sodium bisulfite, ascorbic acid, sodium formaldehyde sulfoxylate, or azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, lauroyl par Known polymerization initiators comprising monomer-soluble (oil-soluble) initiators such as oxides and t-butyl peroxypivalate, and combinations of these with the above-described reducing agents for redox initiators are used.

The emulsifier used for the polymerization may be any one of known emulsifiers such as alkali metal salts or ammonium salts of higher alcohol sulfates, alkali metal salts or ammonium salts of alkylbenzenesulfonic acid, and alkali metal salts or ammonium salts of higher fatty acids. Or a combination of two or more. The amount of the emulsifier used is preferably 0.1 to 3 parts by weight, particularly preferably 0.3 to 1 part by weight.

In order to carry out the polymerization method of the present invention,
Emulsion polymerization reaction system or fine suspension polymerization reaction system comprising water, vinyl chloride monomer, emulsifier or dispersant, polymerization initiator, etc., is copolymerizable with the copolymerization reactivity ratio r ₂ ≧ 1 M ₂ was added to or continuously divided into two or more times,
This addition operation was performed after the start of the polymerization reaction, when the copolymerization conversion was 6%.
It must be completed before it exceeds 0%. Particularly, it is preferable to add continuously. Further, the timing of starting the addition of the monomer M ₂ is set until the polymerization conversion reaches 30%.
It is better to start by 20%. When the addition is completed, it is desirable that the copolymerization conversion rate exceeds 50%. Incidentally, the monomer M ₂ can also be the small amount of advance in addition to the emulsion or fine suspension before the start of polymerization, the addition of the remaining majority intermittently or continuously, also, add to it may be intermittently or continuously added after mixing with the vinyl chloride monomer M ₁ to. Upon the addition of the monomer M _2, although it is preferably performed according to the progress of the reaction of the vinyl chloride monomer is a matter of course, which detects the heat of reaction generated by the polymerization reaction, an index the value to to adjust the amount and rate of addition of the monomer M _2. The calorific value of the polymerization reaction can be estimated from the internal temperature of the reactor and the temperature of the inlet and outlet of cooling water such as a jacket. Furthermore, once the polymerization reaction is carried out, if the same method is employed in each step based on the results of the first time, the subsequent production can be easily carried out. After the polymerization reaction, drying is performed by a method such as spray drying or freeze drying to obtain vinyl chloride-based copolymer particles.

A copolymerizable monomer M ₂ such that r ₂ ≧ 1
It is not clear why the division, sequential or continuous addition of has the effect of improving the storage stability of the vinyl chloride copolymer particles in the sol state, but the composition of the vinyl chloride copolymer particles obtained by the polymerization reaction is not clear. Because there is a difference between the outermost shell and the inner layer part, the outer shell part is a vinyl chloride homopolymer or similar, so that the affinity for the plasticizer may be relatively lower than that of a homogeneous copolymer. Inferred. That is, the copolymerizable monomer M ₂ having r ₂ ≧ 1 has a high polymerization reaction due to its high reactivity, and is thus taken into the copolymer particles sequentially. Here, when the addition method as in the present invention is applied, the copolymer particles have a structure as if coated with a vinyl chloride homopolymer or a copolymer containing a small amount of M ₂ as described above. . It is considered that the stability of the viscosity (in the sol state) in the plasticizer is improved for such a reason. The reason why continuous addition is particularly effective is that
Compared to the case of the initial batch addition, the initial reaction copolymerizable monomer M ₂ can not be a thick shell of finally vinyl chloride homopolymer successively copolymerized with vinyl chloride, good meltability It is presumed that it will be. Co-polymerization conversion without particle structure causes generation as described above to continue the addition of copolymerizable monomer M ₂ to beyond 60%, rather the effect of the storage stability deteriorates.

The vinyl chloride copolymer particles of the present invention are mainly used as a plastisol or organosol for flooring, wallpaper,
Used for various applications such as ceiling covering materials, leather, sealing materials, steel sheet covering materials, gloves, etc. To prepare plastisols and organosols, the vinyl chloride-based copolymer particles of the present invention are used as a main resin component, and a plasticizer, a stabilizer, and other necessary antioxidants, ultraviolet absorbers, fillers, antistatic Additives such as a coloring agent, a colorant, an anti-fogging agent and a release agent are uniformly blended.

As the plasticizer, for example, di-n-phthalic acid
Butyl, di-n-octyl phthalate, di-2-phthalate
Ethylhexyl, diisooctyl phthalate, diisononyl phthalate, diisodecyl phthalate, octyldecyl phthalate, butylbenzyl phthalate, di-2 isophthalate
Phthalic acid-based plasticizers such as ethylhexyl, or phthalic acid esters of higher alcohols having about 11 to 13 carbon atoms;
Trimellitic acid plasticizers such as di-n-octyl-n-octyl trimellitate, tri-2-ethylhexyl trimellitate, triisodecyl trimellitate, and tri-n-octyl trimellitate; di-2-adipic acid Fatty acid ester plasticizers such as ethylhexyl, di-n-decyl adipate, diisodecyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, tributyl phosphate and tri-2 phosphate -Plastic ester plasticizers such as -ethylhexyl, 2-ethylhexyl diphenyl phosphate, tricresyl phosphate, etc .; epoxidized soybean oil, epoxidized linseed oil, epoxidized tall oil; and epoxy plasticizers such as fatty acid-2-ethylhexyl or liquid. Epoxy resin, etc.,
These may be used alone or in combination of two or more. The amount used is in the range of 30 to 200 parts by weight per 100 parts by weight of the resin component such as vinyl chloride copolymer particles.

The stabilizers include lead, barium-zinc, calcium-zinc, magnesium-zinc, and calcium-barium known as stabilizers for vinyl chloride resins.
Cadmium-barium, barium-zinc-tin, cadmium-barium-zinc, organic tin and other stabilizers can be used. The amount of the stabilizer used is 0.1 to 5 parts by weight, preferably 0.15 to 3 parts by weight, per 100 parts by weight of the resin component such as vinyl chloride-based copolymer particles.
Parts by weight. If the content is too small, the thermal stability is insufficient, and even if the content is more than a suitable amount, the effect corresponding to the added amount cannot be increased, which is not economical.

[0017]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. The “parts” and “%” described in the examples are based on weight. Table 1 shows the copolymerizable monomers (comonomer) used and the copolymerization reactivity ratios r ₁ and r ₂ .

<Evaluation method of formed vinyl chloride copolymer particles> Viscosity stability 100 parts of vinyl chloride copolymer and 60 parts of di-2-ethylhexyl phthalate (DOP) are mixed and made into a sol using a Hobart mixer. The obtained plastisol was used with a B8H type viscometer (Brookfield V) manufactured by Tokyo Keiki Co., Ltd.
The viscosity is measured at 50 rpm of an isometer.
The value is defined as B ₅₀ (init). This sol is stored in a constant temperature chamber at 40 ° C., and one week later, the viscosity is measured again, and the value is defined as B ₅₀ (1 w). The viscosity ratio B of these two
₅₀ (1w) / B ₅₀ (init) was converted to AI (Aging I)
ndex) was used as an index of viscosity stability. The smaller the value, the better the viscosity stability.

Melt physical properties 100 parts of vinyl chloride copolymer, 60 parts of DOP and Ca
3 parts of a Zn-based stabilizer are stirred and mixed with a chemi-stirrer, and coated on a glass plate so as to have a film thickness of 1 mm. This is held at 140 ° C. for 30 minutes to gel, and the test piece is punched into a dumbbell such that the cut portion has a width of 5 mm. With respect to the punched film, the breaking strength (TS) and the elongation at break (EL) were determined at a tensile speed of 200 mm / min with a tensile tester (manufactured by Instron), and these values were used as a measure of gelation / meltability. I do.

<Preparation of Seed Polymer-1> A 200-liter polymerization tank equipped with a stirrer was charged with 90 kg of deionized water at a temperature of 54 ° C., 10 g of potassium persulfate, and 50 g of sodium pyrosulfite. Stir for a minute to dissolve.
Next, the pressure inside the polymerization tank was reduced to 150 mmHg, and the temperature was kept at 55 ° C for 50 minutes. Next, 60 kg of a vinyl chloride monomer was charged into the polymerization tank, and the temperature in the tank was raised to 50 ° C. After 15 minutes from the charging of the monomer, a 0.2% aqueous potassium persulfate solution previously dissolved was gradually added at a rate of about 10 ml / min, and thereafter, a constant polymerization rate was maintained. The reaction was performed while controlling the rate of addition of the aqueous solution of potassium persulfate. When the polymerization rate reached about 15%, the addition of the separately dissolved aqueous solution of sodium lauryl sulfate was started, and the aqueous solution was added at about 80 ml / 10 minutes. At a rate of until the total amount of sodium lauryl sulfate added reached 360 g. The reaction was stopped when the pressure in the tank dropped 2.0 kg / cm ² from the saturation pressure of the vinyl chloride monomer at 50 ° C.,
The unreacted monomer was recovered to obtain a polymer latex. The latex was composed of monodispersed particles having a particle size of about 0.49 μ and had good stability.

Example 1 Deionized water 80 was added to a 200-liter polymerization tank equipped with a stirrer.
kg, 4.5 kg (in terms of solid content) of the seed polymer latex prepared in Preparation-1 of Seed Polymer, 70 g of sodium pyrosulfite, and 100 g of a 0.03% cupric chloride aqueous solution were charged and then degassed. Top, vinyl chloride monomer 1
6.5 kg was charged and heated to a temperature of 50 ° C. Thereafter, 10 liters of a total amount of 15 g of a 0.1% aqueous solution of ammonium persulfate is initially added continuously at a rate of 10 ml / min for 15 minutes, and then continuously while controlling the addition rate so as to maintain a constant polymerization rate. The polymerization method to be added was adopted. 4 kg (about 4.5 l) of the butyl acrylate monomer was added simultaneously with the addition of the aqueous solution of ammonium persulfate (at this time, the polymerization conversion was substantially 0%, excluding the conversion of the seed polymer. The same was applied.) 1000 ml / hr was continuously added. From the time the copolymerization conversion reached 10% to the end of the polymerization, 0.5 kg of sodium lauryl sulfate was converted into a 10% aqueous solution at a rate of 0.7 l / hr.
Further, 35 kg of vinyl chloride monomer was continuously added at a rate of 7 kg / hr. The point at which the internal pressure of the polymerization tank dropped 1.0 kg / cm ² from the saturation pressure of the vinyl chloride monomer at 50 ° C. was defined as the completion point of the polymerization.

The copolymerization conversion at the completion of comonomer addition calculated from the reaction time is 54%. The time required from the start of the polymerization to the completion of the polymerization was 6 hours and 50 minutes, and the copolymerization conversion of the vinyl chloride copolymer was calculated to be 82%.
After the completion of the polymerization, the unreacted monomer was recovered, and the latex was filtered through a 20-mesh wire gauze, then frozen in a dry ice-ethanol bath and vacuum-dried to obtain vinyl chloride copolymer particles. Table 1 shows the method of adding the comonomer, the copolymerization conversion at the end of the addition, the reaction time, the final copolymerization conversion, and the evaluation results of the copolymer particles (the same applies to the following Examples and Comparative Examples). .

Examples 2 and 3 Copolymer particles were produced in the same manner as in Example 1, except that the comonomer was changed to octyl acrylate and 2-hydroxypropyl acrylate. However,
In Example 3, the comonomer charge amount was adjusted to 3.2 kg, and the addition rate was adjusted to 610 ml / hr.

Example 4 Except that butyl acrylate was added to the polymerization system at a copolymerization conversion of 15, 30, 45 and 60% by intermittently press-fitting 1 kg each from a pressurized addition tank. In the same manner as in Example 1, copolymer particles were produced.

Comparative Example 1 Copolymer particles were produced in the same manner as in Example 1 except that 4 kg of butyl acrylate was initially added (just before the addition of the vinyl chloride monomer).

Comparative Example 2 In Example 1, copolymer particles were obtained by adding butyl acrylate to the polymerization system continuously at a rate of 700 ml / hr from when the polymerization conversion reached about 30%. Was. Immediately after the completion of the comonomer addition, the copolymerization conversion had already reached 77%, and the finally obtained copolymer particles had poor viscosity stability as is clear from Table 1.

Comparative Example 3 Copolymer particles were produced in the same manner as in Example 1 except that the comonomer was changed to a vinyl acetate monomer.

<Preparation of Seed Polymer-2> 100 kg of ion-exchanged water was placed in a 200-liter premixing tank equipped with a stirrer.
After adding 600 g of lauroyl peroxide, 400 g of sodium lauryl sulfate and 200 g of lauryl alcohol, the premixing tank was degassed and the vinyl chloride monomer 60 k
g was added and maintained at 35 ° C. with stirring. After uniformly stirring, a volume 2 equipped with a stirrer previously degassed while dispersing to a desired droplet diameter using an emulsifier (homogenizer).
It was transferred to a 00 l reaction tank. After the transfer of the dispersion was completed, the temperature of the reaction vessel was raised and polymerization was carried out by a known method. The average diameter of the seed polymer particles in the obtained latex was 0.55 μm.

Example 5 Using the seed polymer prepared in Preparation-2 of seed polymer, polymerization was carried out as follows. Volume 20 with stirrer
80 kg of deionized water, 5 kg of seed polymer latex (in terms of solid content), 200 g of 0.05% cupric chloride aqueous solution and 20 g of sodium hydrogen carbonate were charged into a 0 l polymerization tank, and then degassed and 20 kg of vinyl chloride monomer was charged. Was heated to a temperature of 47 ° C., and a 0.5% aqueous solution of sodium formaldehyde sulfoxylate previously dissolved therein was added little by little and a total of 5 l of a 0.02% aqueous cupric chloride solution in 15 m.
The polymerization was started by continuously adding the mixture at a rate of 1 / min to the polymerization tank. Thereafter, the addition amount of the aqueous sodium formaldehyde sulfoxylate solution was adjusted so as to have a constant polymerization reaction rate. After the start of the polymerization, when the polymerization conversion reaches about 8%, 35 kg of vinyl chloride monomer is added at a rate of 8 kg / hr, and at the same time, the total amount of butyl methacrylate is 5 k.
4 kg of this g was continuously added in proportion to the amount of heat generated by the polymerization until the conversion of copolymerization reached 45%, and the remaining 1 kg was continuously added until the conversion of polymerization reached 57% while keeping the amount of heat generated by polymerization constant. Further, when the copolymerization conversion reaches 10%,
Until the end of the polymerization, 5 l of an 8% sodium dodecylbenzenesulfonate aqueous solution separately prepared as an emulsifier was added to 1 l /
It was added continuously at the rate of hr. Polymerization tank pressure is 47 ° C
1.5kg / c from saturation pressure of vinyl chloride monomer
When m ² dropped, the polymerization was stopped and unreacted monomer was recovered. The average particle size of the obtained latex was 1.1 μ, and the stability of the latex was good. This was freeze-dried in the same manner as in Example 1 to obtain copolymer particles.

Examples 6 and 7 Copolymer particles were produced in the same manner as in Example 5 except that the comonomer was changed to methyl acrylate and butyl acrylate, respectively.

Comparative Example 4 Vinyl chloride copolymer particles were produced in the same manner as in Example 5 except that the comonomer was changed to vinyl acetate.

Comparative Example 5 The addition of 5 kg of butyl methacrylate was carried out at a polymerization conversion of about 30.
%, And the addition rate was adjusted in proportion to the amount of heat generated by the polymerization. However, it took a long time for the addition due to insufficient cooling, and the comonomer addition could be completed until the copolymerization conversion reached 60%. could not. As a result, the viscosity stability of the copolymer particles in the sol was poor. Copolymer conversion rate 60%
It can be seen that it is necessary to increase the cooling capacity in order to complete the addition of the comonomer before reaching.

[0033]

[Table 1]

[0034]

The vinyl chloride copolymer particles of the present invention are:
Particles in which the outer shell is a copolymer containing a small amount of monomer M ₂ or a vinyl chloride homopolymer, and a layer of a copolymer rich in monomer M ₂ is formed inside the outer shell. Since it has a structure, the gelling and melting properties of the resin are not impaired, and the sol composition such as plastisol or organosol using the resin particles has good storage stability.

Claims (1)

[Claims] 1. A vinyl chloride monomer produced by copolymerizing a vinyl chloride monomer M ₁ and a monomer M ₂ copolymerizable therewith and having a copolymerization reactivity ratio r ₂ of 1 or more. Copolymer particles whose outer shell is composed of monomer M ₂
The is a copolymer or a vinyl chloride homopolymer slight includes, characterized in that the internal layer of the monomer M ₂ rich copolymer is formed in the grain structure of the shell portion chloride Vinyl copolymer particles.