JPH09208631A - Vinyl chloride polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vinyl chloride polymer which has excellent balanced elongation properties in forming such as vacuum forming by specifying the degree of polymerization and mol.wt. distribution of a vinyl chloride polymer. SOLUTION: This vinyl chloride polymer has an average mol.wt. of 600 to 1,400 and meets a relationship represented by the fromula: 2.15<=Mw/Mn<=5; and 1.75<=Mz/Mw<=5 wherein Mn represents the no. average mol.wt., Mw represents the wt. average mol.wt., and Mz represents the average mol.wt. It is prepd. by adding a compd. having in its molecule at least two ethylenically unsatd. double bond in an amt. of 0.01 to 1wt.%, based on a vinyl chloride monomer, in the suspension polymn. of a vinyl chloride monomer or a copolymerizable monomer mixture composed mainly of a vinyl chloride monomer in an aq. medium in the presence of an oil-soluble initiator. This vinyl chloride polymer has good melt properties at a temp. comonly used in vacuum forming (150 to 230 deg.C) and good conformability of the corner portion of a molding to a mold, rendering the thickness of the resultant molding even.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vinyl chloride polymer having excellent processing characteristics. More particularly, it relates to a vinyl chloride polymer having an excellent balance of elongation properties during secondary processing such as vacuum forming, and a method for producing the same.

[0002]

2. Description of the Related Art Vinyl chloride polymers are excellent in physical properties.
It is a resin with mechanical properties and is widely used for molded products such as hard and soft. In addition, by adding processing aids such as modifiers and lubricants, plasticizers, and heat stabilizers together with the vinyl chloride polymer, the processability and product quality can be adjusted in various ways. It is used in large quantities as a material that can be used for various purposes.

Films, sheets, plates and the like made of vinyl chloride type polymers are used for industrial parts, for example, by vacuum forming.
It is processed into parts for home electric appliances and computers, molded products such as daily sundries and toiletries, and is used in each field, but large size of molded products, high-speed production to improve production efficiency and simultaneous molding of many molded products. With the progress of production (so-called “multi-cavity production”), vinyl chloride-based polymers capable of meeting such molding conditions have been desired.

[0004]

DISCLOSURE OF THE INVENTION In vacuum forming,
It is said that the melting characteristics at around 150 to 230 ° C., which is a commonly used molding temperature, are important. If the melting characteristics in this temperature range are inappropriate, the corners (corners) of the molded product may not be molded as the mold, and the product may have an uneven wall thickness. There is.

As the processing characteristics, particularly the elongation characteristics, required for the raw material sheet for performing this vacuum forming satisfactorily, the sheet uniformly expands with a low stress at the time of low strain in the initial stage of molding (that is, the elongation viscosity is low), and The stress of the sheet is high (that is, the extension viscosity is high) at the time of high strain (at the time of thinning) in the latter stage of molding. Conventionally, in order to improve the above-mentioned molding processability in a polyvinyl chloride-based sheet, a low stress is maintained at a low strain by selecting the polymerization degree of the vinyl chloride-based polymer and a high molecular weight acrylic copolymer is mainly used. The major improvements were made in terms of compounding, such as improving the stress at high strains by adding the modifier. However, the method of improving the elongation property by using a processing aid such as a modifier has problems such as an increase in compounding cost due to the addition of the additive, complication of the compounding, and an increase in viscosity at low strain due to the added additive. There was not always enough.

[0006]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies for the purpose of solving the above problems by improving the vinyl chloride polymer itself, and as a result, have found that the specific degree of polymerization and the molecular weight distribution It was found that the vinyl chloride-based polymer having γ satisfies the above-mentioned various properties. That is, the gist of the present invention is that the average degree of polymerization is 600 to 1400, and the number average molecular weight (“M
n ”), the weight average molecular weight (denoted as“ Mw ”), and the Z average molecular weight (denoted as“ Mz ”) of the vinyl chloride polymer.

[0007]

## EQU5 ## 2.15 ≦ Mw / Mn ≦ 5

[0008]

(6) 1.75 ≦ Mz / Mw ≦ 5

The gist of the present invention is that the average degree of polymerization is 650.
To 1100, and the vinyl chloride polymer having the following relationship among the number average molecular weight, the weight average molecular weight and the Z average molecular weight.

[0010]

## EQU7 ## 2.15 ≦ Mw / Mn ≦ 3.5

[0011]

## EQU00008 ## 1.75 ≦ Mz / Mw ≦ 3.5

Another subject matter of the present invention resides in the above-mentioned polymer for vacuum forming, and another subject matter of the present invention is a vinyl chloride monomer or a copolymer mainly comprising vinyl chloride monomer. When a mixture of various monomers (hereinafter collectively referred to as “vinyl chloride-based monomer”) is subjected to suspension polymerization in an aqueous medium using an oil-soluble polymerization initiator, two or more are included in the molecule. The method for producing a vinyl chloride-based polymer, wherein the compound having an ethylenic double bond is added in an amount of 0.01 to 1% by weight with respect to the vinyl chloride-based monomer, and two or more ethylenic diesters in the molecule The method for producing a vinyl chloride polymer described above also uses diallyl phthalate as a compound having a heavy bond.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. <Average degree of polymerization> The term “average degree of polymerization” as used in the present invention means JI
It is the viscosity average degree of polymerization specified in SK-6721. If this average degree of polymerization is too low, such as less than 600, the strength of the product will be reduced, or the stress at high strain will be insufficient, causing defective molding of the corners of the molded product. In addition, the sheet or the like may soften and hang down during preheating before molding, which may cause wrinkles or the like on the molded product. On the other hand, when the average degree of polymerization exceeds 1400 and becomes high, the viscosity at low strain during vacuum forming becomes high, which makes it difficult to uniformly spread and also deteriorates the surface appearance of the molded product or a sheet which is a raw material for vacuum forming. The kneading torque becomes high at the time of manufacturing, or the kneading takes a long time. Average degree of polymerization is 6
It is more preferably in the range of 50 to 1100.

<Molecular Weight Distribution> The molecular weight distribution of the present invention can be measured by a gel permeation chromatography method using tetrahydrofuran (THF) as an eluent. Mw / Mn and Mz / Mw are 2.15 respectively
If it is less than the preferred range of the present invention, such as less than less than or less than 1.75, the stress at high strain of the softened sheet at the time of vacuum forming becomes low, so that the wall thickness of the molded product tends to become uneven, while these values are If both are higher than 5, the elongation at the time of molding tends to be insufficient. Mw / M
n is 2.15 or more and 3.5 or less, and Mz / Mw is 1.
It is more preferably 75 or more and 3.5 or less from the viewpoint of vacuum formability.

<Use of the Vinyl Chloride-Based Polymer of the Present Invention> The vinyl chloride-based polymer of the present invention can be processed by a calendering method, an extrusion-molding method, an injection-molding method or the like, like the general vinyl chloride-based polymer. It can be used for a wide range of applications from hard to soft, but especially after once being formed into a sheet or film, these sheets etc. are secondary processed by vacuum forming method or blow molding method etc. It can be said that this is a preferable application because the good elongation property is sufficiently exhibited when it is used for such a purpose.

<Production Method of Vinyl Chloride-Based Polymer of the Present Invention> The production method of the vinyl chloride-based polymer of the present invention is not particularly limited. When suspension polymerization is performed in an aqueous medium using an agent, a compound having two or more ethylenic double bonds in the molecule (hereinafter sometimes referred to as “crosslinking agent”) is added to the vinyl chloride-based monomer. It can be suitably manufactured by a method of adding 0.01 to 1% by weight.

The compound having two or more ethylenic double bonds in the molecule used in the method of the present invention is
For example, allyl esters of polyvalent organic acids such as diallyl phthalate, diallyl malate, diallyl succinate, triallyl cyanurate, and triallyl isocyanurate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, bisphenol A-modified dimethacrylate, and triaryl methacrylate. (Meth) acrylic acid esters of polyhydric alcohols such as methylolpropane triacrylate, or divinylbenzene can be used. Among them, diallyl esters and triallyls of polyvalent organic acids such as diallyl phthalate and triallyl isocyanurate. Ester is preferable because it has moderate reactivity with the vinyl chloride monomer and good reaction controllability. In particular, diallyl phthalate is suitable for the purpose of the present invention because it can suppress the formation of a gel component described below by selecting the addition amount and reaction conditions.

The compounds having two or more ethylenic double bonds in the molecule can be used alone or in combination of two or more kinds. The addition amount thereof is usually 0.01 to 2 parts by weight, preferably 0.05 to 0.5 parts by weight, per 100 parts by weight of the vinyl chloride-based monomer. When a compound (crosslinking agent) having two or more ethylenic double bonds in the molecule is added, a crosslinked product (gel component) which is not dissolved in tetrahydrofuran (THF) may be produced. If such a gel content is present in a large amount in the polymer, the elongation at the time of forming the vacuum formed sheet becomes insufficient,
The gel content is preferably 5% by weight or less in the polymer because molding defects such as holes may occur. The gel content can be adjusted by the type and amount of the compound having an ethylenic double bond in the molecule, the addition method (collective addition, sequential (divided) addition, continuous addition), addition time (before polymerization start, during polymerization). It is possible by experimentally selecting (specific polymerization conversion rate) and the like.

The gel content in the polymer can be measured, for example, as the content of insoluble matter obtained by stirring and dissolving 2 g of vinyl chloride polymer in 30 ml of THF, allowing to stand overnight, centrifuging and drying. . In the present invention, the values obtained for the THF-soluble component in the polymer are used as the average polymerization degree and the value of the molecular weight distribution when there is a gel component.

In carrying out the above method, for example, trichloroethylene, 2-mercaptoethanol,
A chain transfer agent such as 2-pentene or isopropyl alcohol is added in an amount of 0.001 per 100 parts by weight of the vinyl chloride monomer.
Addition of 0.1 to 0.1 parts by weight is preferable because the control range of the molecular weight distribution is widened.

The vinyl chloride monomer used in the present invention includes vinyl chloride monomer alone and a mixture of copolymerizable monomers mainly composed of vinyl chloride monomer. Other monomers copolymerizable with the vinyl chloride monomer include those conventionally used in the polymerization of vinyl chloride monomers, for example, vinyl esters such as vinyl acetate and vinyl propionate, octyl. Alkyl vinyl ethers such as vinyl ether and cetyl vinyl ether, α-olefins such as ethylene and propylene, (meth) acrylic acid alkyl esters such as methyl acrylate and methyl methacrylate, or vinylidene compounds such as vinylidene chloride can be used. Well, it is not particularly limited. These other monomers are usually used in a proportion of 20% or less with respect to the vinyl chloride monomer.

In the suspension polymerization of the above vinyl chloride-based monomer, as a dispersant, for example, partially saponified polyvinyl acetate (so-called polyvinyl alcohol), a cellulose derivative such as hydroxypropylmethyl cellulose, a water-soluble polymer such as gelatin, etc. Is a vinyl chloride monomer 1
It is preferable to use 0.001 to 0.15 parts by weight per 00 parts by weight.

Examples of the polymerization initiator include t-butylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxypivalate and t.
-Hexyl peroxy neodecanoate, perester compounds such as α-cumyl peroxy neodecanoate,
Peroxide compounds such as dilauroyl peroxide,
Percarbonate compounds such as diisopropyl peroxydicarbonate and di-2-ethylhexyl peroxydicarbonate, azo compounds such as azobis (2,4-dimethylvaleronitrile) and azobisisobutyronitrile, etc., and vinyl chloride monomer 100 weight 0.01 per copy
-1 part by weight may be used.

Further, in the method of the present invention, various polymerization aids such as an antioxidant, a pH adjuster, and a scale adhesion preventive agent, which are used for suspension polymerization of vinyl chloride-based monomers, may be used, if necessary. They can be used, and the addition amount and addition method of each of these components may be the general conditions conventionally used for polymerization of vinyl chloride monomers.

<Compounding agent at the time of molding / processing> When molding / processing the vinyl chloride polymer of the present invention, a plasticizer, a heat stabilizer, which is usually used at the time of molding / processing the vinyl chloride polymer, Fillers, processing aids (lubricants, modifiers, etc.), pigments,
Weather resistance improver, antifogging agent, antistatic agent and other additives,
It can be used by mixing depending on its purpose and use.

[0026]

EXAMPLES Next, the specific contents of the method of the present invention will be explained using examples, but the present invention is not limited as long as the gist thereof is not exceeded.
It is not limited by the following examples. <Physical property measuring method> The physical properties of the obtained vinyl chloride polymer were evaluated by the following physical property measuring methods. Average degree of polymerization Measured according to the method shown in JIS K6721. Molecular weight distribution (number average molecular weight, weight average molecular weight, Z average molecular weight) It was measured under the following conditions using a gel permeation chromatograph.

[0027]

[Table 1] Device: Tosoh Corp. HLC-8020 type column: Tosoh G6000HXL, G5000HXL G4000HXL, G3000HXL Column size: Diameter 7.8 mm x length 300 mm x 4 Measurement temperature (column chamber): 30 ° C (injection port) ): 38 ° C. (detector): 38 ° C. Eluent: Tetrahydrofuran (first-grade reagent, containing BHT), 0.8 ml / min Detector: RI (differential refractive index type) Sample concentration: 0.2 wt% Sample injection amount : 200 μl Sample preparation: 5 g of a vinyl chloride polymer was dissolved in 100 ml of the above THF, and the solution was left for one day and one night (the gel-containing one was filtered off) to give a sample solution.

Elongational Viscosity 100 parts by weight of the obtained vinyl chloride polymer was mixed with 3.5 parts by weight of a maleate polymer tin stabilizer and 0.1 part by weight of a polyethylene wax, and this was mixed with a twin-screw extruder ( 2D25S type full flight manufactured by Toyo Seiki Co., Ltd. is used as an extrusion molding condition and a predetermined cylinder temperature (C1: 170 ° C.,
C2: 180 ° C., C3: 190 ° C., D: 200 ° C.) and screw rotation speed (50 rpm), extrusion rate 5 kg /
As h, a strand having a diameter of 4 mm was extruded by a strand die. The extensional viscosity of this strand was measured by the following method.

[0029]

[Table 2] Equipment: Toyo Seiki Seisakusho Co., Ltd. Melten Rheometer HW Measurement mode: Constant strain rate measurement Measurement temperature: 190 ° C (oil constant temperature bath temperature) Set strain rate: 0.01 / 0.03 / 0. 3 (sec-1) Preheating time: 10 minutes

<Example 1> In a stainless steel polymerization vessel equipped with a stirrer and a jacket having an internal volume of 400 liters, 160 kg of deionized water and 90 parts of a partially saponified water-soluble polyvinyl acetate were added.
g and 130 g of diallyl phthalate (0.1 part by weight per 100 parts by weight of vinyl chloride monomer) as a cross-linking agent were charged and degassed by suction with a vacuum pump. Next, 130 kg of vinyl chloride monomer and 65 g of a polymerization initiator (t-butylperoxypivalate) were charged, and polymerization was carried out at a reaction temperature of 67 ° C.

When the internal pressure of the reactor was lower than the saturated vapor pressure of the vinyl chloride monomer at that temperature by 3 kg / cm 2, the unreacted monomer was recovered and the polymerization was terminated. The resulting slurry was centrifugally dehydrated and then dried to obtain a vinyl chloride polymer. Using this polymer, the average degree of polymerization, the molecular weight distribution and the extensional viscosity were measured according to the methods described above. The results are shown in the table.

Example 2 The amount of diallyl phthalate used was 260 g (0.2 per 100 parts by weight of vinyl chloride monomer).
Parts by weight), and polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was 70 ° C. to obtain a vinyl chloride-based polymer, and the same evaluation was applied thereto. The results are shown in the table.

<Example 3> In Example 2, the polymerization temperature was set to 68 ° C and the polymerization was initiated. When the reaction rate reached 20%, 2-mercaptoethanol 6 as a chain transfer agent was used.
Polymerization was carried out in the same manner as in Example 2 except that 5 g (0.05 parts by weight per 100 parts by weight of vinyl chloride monomer) was added. The obtained vinyl chloride polymer was evaluated in the same manner. The results are shown in the table.

Example 4 In place of 130 g of diallyl phthalate in Example 1, 65 g of triallyl isocyanurate (0.05 g per 100 parts by weight of vinyl chloride monomer) was used.
Polymerization / evaluation was carried out in the same manner as in Example 1 except that the polymerization temperature was 67 ° C. The results are shown in the table.

<Example 5> In Example 4, the polymerization temperature was set to 67 ° C, and the amount of triallyl isocyanurate was set to 78 g.
Example 4 except that (0.06 parts by weight per 100 parts by weight of vinyl chloride monomer) was used and the polymerization temperature was 68 ° C.
Polymerization and evaluation were carried out in the same manner as. The results are shown in the table.

Comparative Example 1 Polymerization and evaluation were carried out in the same manner as in Example 1 except that diallyl phthalate was not used and the polymerization temperature was 65 ° C. The results are shown in the table.

Example 6 In Example 1, the polymerization temperature was set to 61 ° C., and the amount of diallyl phthalate added was 130 g.
(0.1 parts by weight per 100 parts by weight of vinyl chloride monomer)
Polymerization and evaluation were performed in the same manner as in Example 1 except that the above was adopted. The results are shown in the table.

Comparative Example 2 Polymerization and evaluation were carried out in the same manner as in Example 6 except that diallyl phthalate was not used and the polymerization temperature was 58 ° C. The results are shown in the table.

[0039]

[Table 3]

<Evaluation of Results> As shown in the table, the vinyl chloride polymer of the present invention has the following characteristics and is particularly suitable for vacuum forming into a film or sheet form. (1) When the strain is low (typically represented by the extensional viscosity at point A in the figures and table): It is equivalent to a general-purpose vinyl chloride resin that is often used for vacuum forming, and uniform elongation is secured at the initial stage of forming. (2) High strain (time required to reach point B in the figure and table and B
(Extension viscosity at point): Since point B is reached in a short time, it quickly reaches a high viscosity region in the process of thinning, and the extension viscosity at that time is also high. That is, even when the elongation is large, the risk of uneven thickness (local thinning) is reduced. Moreover, since the stress at the time of breaking is large, the possibility of perforation and breaking can be reduced.

[0041]

The vinyl chloride polymer of the present invention has a molding temperature (150 to 230) generally used in vacuum molding.
The melting characteristics at (° C.) are good, the mold followability of the corners (corners) of the molded product is good, and the thickness of the obtained product is uniform.

[Brief description of drawings]

FIG. 1 shows a logarithmic log graph (vertical axis: extensional viscosity, horizontal axis: time) of extensional viscosity measurement results (Example 2).

FIG. 2 shows a logarithmic log graph (vertical axis: extensional viscosity, horizontal axis: time) of extensional viscosity measurement results (Comparative Example 1).

[Explanation of symbols]

 Point A: Point 1 second after the start of measurement Point B: Boundary point between linear and non-linear regions on the figure Point C: Break point

Claims (6)

[Claims] 1. An average degree of polymerization of 600 to 1400, a number average molecular weight (referred to as "Mn"), a weight average molecular weight ("M").
a vinyl chloride polymer such that the following relationship is established between the "w") and the Z average molecular weight ("Mz"). ## EQU1 ## 2.15≤Mw / Mn≤5 ## EQU2 ## 1.75≤Mz / Mw≤5 2. The vinyl chloride polymer according to claim 1, which has an average degree of polymerization of 650 to 1100. 3. The vinyl chloride polymer according to claim 1, wherein the following relationship is established among the number average molecular weight, the weight average molecular weight and the Z average molecular weight. (3) 2.15 ≦ Mw / Mn ≦ 3.5 (4) 1.75 ≦ Mz / Mw ≦ 3.5 4. The vinyl chloride polymer for vacuum forming according to claim 1. 5. An oil-soluble vinyl chloride monomer or a mixture of copolymerizable monomers mainly composed of vinyl chloride monomer (hereinafter collectively referred to as “vinyl chloride-based monomer”). When suspension polymerization is carried out in an aqueous medium using a polymerization initiator, a compound having two or more ethylenic double bonds in the molecule is added in an amount of 0.01 to 1% by weight based on the vinyl chloride-based monomer.
The method for producing the vinyl chloride polymer according to any one of claims 1 to 4, wherein the vinyl chloride polymer is added. 6. The method for producing a vinyl chloride polymer according to claim 5, wherein diallyl phthalate is used as the compound having two or more ethylenic double bonds in the molecule.