JPH0446963B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vinyl chloride polymer (hereinafter simply referred to as
This relates to a manufacturing method for PVC (abbreviated as PVC). In particular, the present invention relates to a method for producing impact-resistant PVC with significantly improved heat deformation resistance. PVC is cheaper than other resins and
Various molded products obtained from this resin have excellent physical properties and are therefore widely used as a highly versatile resin. However, as the uses of PVC expand, there is a strong demand for improved mechanical properties. In particular, PVC has poor impact resistance and heat modification resistance compared to other general-purpose resins, and various modification methods have been implemented to improve this. As a method for improving the impact resistance of PVC, methods such as blending a rubbery impact modifier and a modification method using graft copolymerization are generally employed. That is, methods of blending rubbery or elastic materials (methacrylate-butadiene-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, etc.) with PVC, thermoplastic resins (polyethylene, ethylene-vinyl acetate copolymers, etc.), , a method of graft polymerizing vinyl chloride monomer onto an elastic material such as ethylene-propylene copolymer, and a method of graft polymerizing the graft copolymer obtained above.
This includes methods of blending it into PVC. however,
The impact-resistant PVC obtained by these modification methods is
Other mechanical properties, such as tensile strength, heat distortion temperature, hardness, transparency, and weather resistance, have the disadvantage of being adversely affected by the contained rubber. Further, when the above-mentioned impact modifier is blended with PVC, the impact modifier is subject to certain restrictions regarding dispersibility in PVC. In other words, in order to have the desired impact properties,
Impact modifiers that are dispersed as a rubbery phase in a PVC phase must have their dispersion size carefully regulated. Furthermore, excellent adhesion between the PVC phase and the rubbery phase is required at the same time, and the blending technique is difficult. Therefore, the present inventors have conducted extensive research in order to obtain impact-resistant PVC that compensates for the above-mentioned defects. As a result, by performing gas phase polymerization of vinyl chloride monomer in the presence of a crosslinked polymer containing a radical polymerization initiator with controlled crosslinking density, impact-resistant PVC with significantly improved heat deformation resistance was produced. The present inventors have discovered that the present invention can be obtained, and have completed the present invention. That is, in the present invention, the obtained crosslinked polymer is slightly swollen or not dissolved in an organic solvent,
Radical polymerization is initiated by radically polymerizing a radically polymerizable monomer and a crosslinking agent in the presence of a radical polymerization initiator so as to maintain a crosslinking density that allows the resulting crosslinked polymer to swell into the vinyl chloride monomer. A crosslinked polymer containing a radical polymerization initiator is obtained, and then a vinyl chloride monomer or a copolymerizable vinyl monomer mainly composed of vinyl chloride monomer is obtained in the presence of a crosslinked polymer containing the radical polymerization initiator. This is a method for producing a vinyl chloride polymer, characterized in that the mixture is supplied at a pressure lower than the saturated vapor pressure of the vinyl chloride monomer and polymerized. The radically polymerizable monomer that can be used in the present invention is not particularly limited, and known monomers can be used. Generally, those having ethylenically unsaturated groups, such as olefin compounds such as ethylene and propylene; halogenated vinyl compounds such as vinyl chloride, vinyl bromide, and vinylidene chloride; vinyl esters such as vinyl acetate and vinyl propionate; acrylic acids and unsaturated monocarboxylic acids such as α-alkyl acrylic acid, and their alkyl esters, amides, i.e., alkyl acids, methacrylic acid, ethyl acrylate, methyl methacrylate, acrylic acid amide, methacrylic acid amide, etc.; Unsaturated nitriles such as acrylonitrile; unsaturated dicarboxylic acids such as maleic acid and fumaric acid, their alkyl esters, and their anhydrides; vinyl alkyl ethers such as vinyl methyl ether and vinyl ethyl ether; dienes such as butadiene and isoprene. styrene and styrene-substituted monomers; and various other known radically polymerizable monomers can be used. As the crosslinking agent used in the present invention, crosslinkable monomers having two or more radical reactive functional groups in one molecule or oligomers thereof can be suitably used. Commonly preferred examples include divinylbenzene, butadiene, triallyl cyanurate, dicyclopentadiene, vinyl methacrylate, vinyl crotonate, vinyl adipate, ethylidene norbornene, diallyl phthalate, diallyl maleate, etc. compounds, dimethacrylate compounds such as polyethylene glycol dimethacrylate or 1,3-butylene dimethacrylate, diacrylate compounds such as polyethylene glycol diacrylate or 1,3-butylene diacrylate, trimethylolpropane trimethacrylate or trimethylolpropane triacrylate, etc. or oligomers thereof, and polybutadienes such as 1,2-polybutadiene, epoxidized 1,2-polybutadiene, hydroxyl-terminated 1,2-polybutadiene, and carboxyl-terminated 1,2-polybutadiene. etc. Among these, the molecular weight of the oligomer is not limited, but it is preferably from 100 to 5,000.
In addition, the amount of crosslinking agent used is closely related to the crosslinking density of the crosslinked polymer, and is not necessarily limited.
Generally, it is desirable that the amount is in the range of 0.05 to 10.0% by weight, preferably 0.1 to 5.0% by weight, based on the radically polymerizable monomer. The organic solvent used in the present invention slightly inhibits the crosslinked polymer obtained by polymerizing the crosslinkable monomer or a mixture of the crosslinkable monomer and other copolymerizable monomers. Any material can be used without particular limitation as long as it swells or does not dissolve. Such organic solvents can generally be defined using the following scale. X=(Vs/RT)(δs−δp) ² ...(1) However, X is the Flory-Huggings interaction constant, which is a unique value between polymer and solvent (Journal of Chemical Physics). of
(chemical physics) Volume 9, pp. 440, 660 (1941),
Volume 10, page 51 (1942)). Vs is the molar volume of the solvent, R is the gas constant, and T is the absolute temperature. Furthermore, δs and δp
are the solubility parameters of the solvent and the polymer compound, respectively, and are derived from the Hilde-brand-Scatchard solution theory (JHHildebrand, “The Solubility of
Nonelectro−lytes.”3rd.ed., Reihhold
Publishing Corporation New York, 1979;G
Scatchard, Chemical Review
Review) vol. 8, p. 321 (1931)). However, it is very difficult to experimentally determine the solubility parameter of a polymer compound, so it can generally be calculated using the following formula proposed by Hoy (KLHoy, Journal of Paint Technology). off
paint technology) vol. 42, p. 76 (1970)). δs(orp)=ρ〓Fi/M (2) where ρ is the density, M is the molecular weight of the monomer, and is the value of the repeating unit in a polymer compound.
In addition, Fi is the molar attraction force for constituent groups such as atoms or atomic group bonds that make up the molecule. The solubility parameters of solvents and crosslinked polymers in the present invention can be found in the Polymer Handbook (John
Willey & Sons, New Yoke, 1975), and for those not mentioned above, (2)
Calculated from the formula. For example, homogeneity calculated from equation (2)
The solubility parameter of PVC is 9.54 (cal/mol) ^1/2
It was hot. When the crosslinked polymer is a copolymer, its solubility parameter can be calculated using equation (2) by determining the density of the copolymer and the composition ratio of monomers. 2) It can be calculated from formula. (1)
The smaller the value of X in the formula, the more easily the crosslinked polymer swells in the solvent. The solvent that can be used in the present invention is preferably a solvent that slightly swells or does not dissolve the crosslinked polymer, and it is preferable to confirm these properties in advance before use. Generally, for example, X in the above formula (1)
It is preferable to use an organic solvent having a value of 0.01 or more and 0.5 or less. In the present invention, typical organic solvents that are particularly preferably used include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and cyclohexanol; aliphatic solvents such as butane, pentane, heptane, and cyclohexane; Alicyclic carbons; ethers such as diethyl ether and methyl ethyl ether;
Fluorine-based organic solvents; etc. Of course, if the crosslinked polymer slightly swells or does not dissolve, for example, the value of X in the above formula (1) is 0.01 or more and 0.5.
A mixed solvent obtained by mixing two or more of the following solvents can also be used. The crosslinked polymer of the present invention is obtained by radical polymerization of a radically polymerizable monomer and a crosslinking agent so as to maintain a crosslinking density that allows swelling with vinyl chloride monomer. The crosslink density, when expressed as the equilibrium weight swelling degree, is the value of the equilibrium weight swelling degree with respect to vinyl chloride monomer under conditions where the measurement temperature is 30°C and the measurement pressure is the saturated vapor pressure of the vinyl chloride monomer. It is preferable to select a range of 1.01 to 10.0 or less. In general, when measuring the parallel impact weight swelling degree of a polymer compound, when the swelling solvent is a liquefied gas such as vinyl chloride monomer, a method is adopted in which the swelling equilibrium is reached in the vapor of the liquefied gas. Bye. In general, it may be determined using an equilibrium gravimetric swelling measurement device obtained by applying the measurement principle proposed by Jenkel. (Jenkel, E., kolloid-Zeitschrift, 127, 83
(1952)). The equilibrium weight swelling degree Q can be calculated as a value obtained by dividing the weight _W5 of the sample when swelling equilibrium is reached by the weight Wd of the sample when drying before swelling, and is expressed by equation (3). Q=Ws/Wd...(3) The crosslinked polymer whose equilibrium weight swelling degree is within the range of, for example, 1.01 to 10.0 under the above measurement conditions is the result of the addition of vinyl chloride monomer or Swells in a mixture of copolymerizable vinyl monomers, mainly vinyl chloride monomers. Therefore, the monomer penetrates into the inside of the particles of the crosslinked polymer, and the vinyl chloride monomer or copolymerizable vinyl mainly composed of vinyl chloride monomer is added to the network structure of the crosslinked polymer. Semi-Interpenetratng Polymer Networks are intricately intertwined polymer molecular chains obtained by polymerizing a mixture of monomers.
PVC formed by is obtained. PVC with such a structure has improved compatibility, dispersibility, and interfacial affinity between different types of polymers, so it has greater mechanical strength than PVC obtained by simple copolymerization or blending of polymers. Improvements in physical characteristics can be achieved. For the reasons mentioned above, the PVC obtained by carrying out the present invention has a transition region from glassy to rubbery over a wide temperature range, and has an improved elastic modulus in the rubbery region. It is an impact-resistant PVC with unique characteristics and has achieved remarkable improvement in heat deformation resistance. In the present invention, the polymerization conditions for obtaining a crosslinked polymer by polymerizing a radically polymerizable monomer and a crosslinking agent in an organic solvent in the presence of a radical polymerization initiator are not particularly limited and are selected from known polymerization conditions. Just do it. For example, generally, a radically polymerizable monomer and a crosslinking agent are dispersed or dissolved in an organic solvent, a radical polymerization initiator is added at the same time, and the temperature is raised to a predetermined polymerization temperature for polymerization. The above-mentioned polymerization temperature is not particularly limited and may be appropriately selected and determined from a known range. Generally, -30℃ to 150℃
Adopted from the range of ℃. Moreover, the polymerization time may be selected and determined as necessary from a range of several minutes to 30 hours. In the present invention, the radical polymerization initiator is not particularly limited, and known ones can be used. for example,
Organic peroxides such as lauroyl peroxide, tert-butyl peroxypivalate, benzoyl peroxide, isopropyldioxycarbonate; azobisisobutyronitrile, α,
Azo compounds such as α'-azobis-4-methoxy-2,4 dimethylvaleronitrile can be preferably used. The amount of the radical polymerization initiator used may be selected from the range of 0.01 to 5% by weight of the monomers used. Further, the radical polymerization initiator can be added either sequentially or in combination of two or more types. In the present invention, a crosslinked polymer containing a radical polymerization initiator is obtained through the above polymerization, and then, in the presence of the crosslinked polymer, vinyl chloride monomer or a vinyl monomer mainly composed of vinyl chloride monomer is The mixture of polymers is subjected to polymerization under the action of the radical polymerization initiator. A method of polymerizing by supplying the vinyl chloride monomer or a mixture of vinyl monomers mainly consisting of vinyl chloride monomer at a pressure lower than the saturated vapor pressure of the vinyl chloride monomer, As long as the polymer is polymerized in the gas phase, ie, at a pressure lower than the saturated vapor pressure of the vinyl chloride monomer, known polymerization techniques can be directly employed. For example, when performing gas-phase polymerization of vinyl chloride monomer, that is, polymerization while continuously supplying vinyl chloride monomer at a pressure lower than the saturated vapor pressure, generally 40°C to 80°C
A polymerization temperature of is preferably employed. Further, the polymerization time is generally preferably 1 hour to 10 hours.
Furthermore, the polymerization pressure for the gas phase polymerization of the present invention must be selected to be lower than the saturated vapor pressure of the vinyl chloride monomer to be polymerized. Generally, relative pressure (Pr) (pressure of vinyl chloride monomer in polymerization system/saturated vapor pressure of vinyl chloride monomer at polymerization temperature)
However, it is sufficient if the condition of 0.5<Pr<1.0 is satisfied. When an organic solvent is present in the polymerization system, a relative pressure below the saturated vapor pressure of the vinyl chloride monomer can be easily set based on the amount of the organic solvent and the vapor pressure at the polymerization temperature. In the present invention, the vinyl monomer copolymerizable with the vinyl chloride monomer is not limited, and known vinyl monomers can be used. Typical examples that can generally be suitably used include, for example, ethylene,
Olefins such as propylene; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethyl acrylate, methyl methacrylate, acrylic amide, and methacrylic amide; Alkyl esters and amides; unsaturated nitriles such as acrylonitrile; unsaturated dicarboxylic acids such as maleic acid and fumaric acid; alkyl esters thereof;
and anhydrous substances thereof; vinyl alkyl ethers such as vinyl methyl ether and vinyl ethyl ether; and the like. The PVC obtained by carrying out the present invention is a resin that has significantly improved heat deformation resistance than impact-resistant PVC obtained by conventional copolymerization methods or polymer blending methods. Although the cause of this is still not clear, the inventors of the present invention assume the following. That is, obtained by carrying out the present invention
PVC forms a semi-interpenetrating network structure in which the polymer molecular chains associated with the crosslinked structure are entangled, which improves the compatibility, dispersibility, and interfacial affinity between different types of polymers, and improves the rubber This is thought to work as an effect of increasing the glass transition temperature to a higher temperature side as well as increasing the elasticity. As a result, it is estimated that impact-resistant PVC with significantly improved heat deformation resistance and improved impact resistance than conventional PVC can be obtained. EXAMPLES In order to explain the present invention in more detail, Examples and Comparative Examples will be given below, but the present invention is not limited to these Examples. Furthermore, the measured values shown in Examples and Comparative Examples were based on the following measurement method. (1) Shalpy impact value Value measured at 23℃ according to JIS K-7111. (2) Vikatsu softening temperature According to JIS K-7206. (3) Equilibrium gravimetric swelling As mentioned above, the equilibrium gravimetric swelling measuring device proposed by Jenkel was used (Jenkel, E., kolloid Zeitschrift,
127, 83 (1952)). (4) Tensile strength After preheating the formed roll-formed sheet at 175℃ for 10 minutes and pressing it at 40Kg/ ^cm3 for 10 minutes, a 1mm-thick sheet was punched out into a No. 2 formed test piece, and JIS-
10mm/min at a temperature of 50℃ according to the method of K-7113
It was measured at a tensile speed of . (5) Particle size distribution PVC was sieved through a 16-mesh sieve (1000 μm) and a 42-mesh sieve (350 μm), and its weight was measured. Example 1 In a glass autoclave equipped with a stirrer, normal heptane, normal butyl acrylate, diallyl phthalate, tertiary butyl peroxy pivalate, and diisopropyl peroxy carbonate were charged in the proportions shown in Table 1 and polymerized at 45°C. A crosslinked polymer of n-butyl acrylate was obtained.
Next, after the apparently liquid normal heptane disappeared, the temperature of the autoclave was raised to 55℃, and 6.2
Kg/ ^cm3 pressure of gaseous vinyl chloride monomer is continuously supplied to increase the pressure inside the autoclave to 6.2~6.5Kg/cm3.
cm ³ and polymerized. Thereafter, the vinyl chloride polymer was collected and dried at 40°C for a day and a night. The results of the heat deformation resistance and impact resistance of the vinyl chloride polymer obtained in this way are determined by the softening temperature and tensile strength (at 50℃).
It is shown in Table 1 as the yalpy impact value. These physical property measurements were performed in the following manner. A mixed sample according to the lead hard compounding method shown in Table A was kneaded using a mixing roll at 170° C. for 5 minutes to obtain a roll-formed sheet with a thickness of about 1.2 mm.
The tensile strength was determined using this molded sheet based on the measurement method described above. In addition, the Vikatsu softening temperature and the Shalpy impact value were measured using the method described above using a 5 mm thick test piece obtained by stacking several molded sheets, preheating them at 180°C for 15 minutes, and pressing them at 200 kg/ ^cm2 for 15 minutes. It was decided based on.

[Table] Note that Table 1 Nos. 4 to 6 are comparative examples. No. 4 is a comparative example in which a crosslinked polymer was obtained without using an organic solvent, and No. 5 is a comparative example in which a crosslinking polymer was obtained without adding a crosslinking agent. Moreover, No. 6 is the measurement result of a vinyl chloride polymer obtained by carrying out only gas phase polymerization in the presence of normal peptane. The equilibrium weight swelling degrees of Examples 1, 2 and 3 were 8.3, 8.7 and 8.9, respectively, and those of Comparative Examples 4 and 5 were 14.3 and 28.5, respectively.

【table】

[Table] Example 2 In a glass autoclave equipped with a stirrer, normal-pentane, normal-butyl acrylate, ethylene glycol diacrylate, and tert-butyl peroxypivalate and diisopropyl peroxycarbonate were added in the proportions shown in Table 2. The mixture was charged and polymerized at 50°C to obtain a crosslinked polymer of n-butyl acrylate. Next, after the apparently liquid normal-pentane disappeared, the temperature of the autoclave was raised to 55°C, and gaseous vinyl chloride monomer at a pressure of 6.2 kg/cm ³ was continuously supplied to increase the pressure inside the autoclave to 6.2 kg/cm 3 . Polymerization was carried out while maintaining the pressure at ~6.5 Kg/cm ³ . Thereafter, the vinyl chloride monomer was collected and dried at 40°C for a day and a night. The heat deformation resistance and impact resistance of the vinyl chloride polymer thus obtained were measured in the same manner as in Example 1. The results are shown in Table 2.

【table】

[Table] Example 3 In a glass autoclave with a stirrer, 60 ml of normal pentane, 35 g of normal butyl acrylate,
1.4 g of ethylene glycol dimethacrylate and 0.7 g of tertiary butyl peroxypivalate,
0.4 g of diisopropyl peroxycarbonate was charged and polymerized at 50°C for 2.0 hours to obtain a crosslinked polymer of n-butyl acrylate. The equilibrium weight swelling degree of the crosslinked polymer was 2.4. Next, after the apparently liquid normal heptane disappeared, the temperature of the autoclave was raised to 55°C, and gaseous vinyl chloride monomer and vinyl acetate were continuously supplied at a pressure of 6.2 Kg/cm ³ to reduce the pressure inside the autoclave. 6.2~6.5Kg/
cm ³ and polymerized for 5.5 hours. The composition of the obtained PVC was 13% by weight of ethylene glycol dimethacrylate crosslinked polymer and 4% by weight of vinyl acetate. The Vikat softening temperature, tensile strength and Charpy impact value of the PVC thus obtained were 76.3℃ and 76.3℃, respectively.
432Kg/cm ³ and 19.9Kg-cm/cm ³ . Example 4 Into a glass autoclave equipped with a stirrer, 70 ml of n-pentane, 10 g of acrylonitrile, 25 g of butadiene, 0.9 g of diallyl phthalate, 0.7 g of tert-butyl peroxypivalate, and 0.3 g of diisopropyl peroxycarbonate were charged.
Polymerization was carried out at 55°C for 1.8 hours to obtain a crosslinked butadiene-acrylonitrile polymer. The equilibrium weight swelling degree of the crosslinked polymer was 9.1. Next, after the apparently liquid normal pentane disappeared, the temperature of the autoclave was raised to 60°C, and gaseous vinyl chloride monomer at a pressure of 7.1 Kg/cm ³ was continuously supplied to increase the pressure inside the autoclave to 7.1 ~ Maintain at 7.3Kg/ ^cm3 ,
Polymerization was carried out for 5.2 hours. The composition of the obtained PVC was 2.9% by weight of acrylonitrile and 7.0% by weight of butadiene. The Vikatsu softening temperature and tensile strength of the PVC thus obtained were 78.2℃, 495Kg/cm ² and
It became 22.3Kg-cm/ ^cm3 .

Claims (1)

[Claims] 1. In an organic solvent that slightly swells or does not dissolve the resulting crosslinked polymer, combine a radically polymerizable monomer and a crosslinking agent with a crosslinking density that allows the resulting crosslinked polymer to swell into vinyl chloride monomer. Radical polymerization is carried out in the presence of a radical polymerization initiator to obtain a crosslinked polymer containing a radical polymerization initiator, and then vinyl chloride monomer is added in the presence of the crosslinked polymer containing the radical polymerization initiator. A vinyl chloride polymer, which is characterized in that a mixture of copolymerizable vinyl monomers mainly consisting of vinyl chloride monomers or vinyl chloride monomers is supplied at a pressure lower than the saturated vapor pressure of the vinyl chloride monomers, and the mixture is polymerized. Method of manufacturing coalescence.