SI9200419A - Vinyl chloride polymer - Google Patents

Abstract

The invention relates to a homo- or copolymer of vinyl chloride. The polymer contains 0.01 - 50 % of an oligomer of a C4-C20 alpha -olefin or of an internal olefin or of their mixtures.

Description

The present invention relates to a homo- or copolymer of vinyl chloride containing α-olefins.

Polyvinyl chloride (PVC) is a cost-effective thermoplastic suitable for many applications. In order to make PVC suitable for processing, various additives such as stabilizers, lubricants, pigments and / or modifiers are added to the resins obtained in the polymerization. The additives are generally mixed into the PVC polymer subsequently before use.

Methods are also known where, in connection with PVC polymerization, monomers or polymers are added to the polymerization reactor to improve the properties of the finished product or regulate the polymerization of vinyl chloride. Thus according to e.g. In US Patent 3560462, at least one C ₁₀ -C ₂₂ α-olefin, preferably hexadecene or octadecene, is added to the vinyl chloride polymerization reactor to prevent the self-accelerating polymerization reaction. The amount of α-olefin is 0.1-5 wt. %.

JP 61155401 discloses a suspension polymerization process wherein 0.1 - 5% by weight of C ₆ -C ₂₀ α-olefins are copolymerized with vinyl chloride. The polymer contains a residual monomer whose content is smaller than normal and whose polymer contains fewer fish eyes.

No. 4031299 discloses a vinyl chloride suspension polymerization process wherein a previously homogenized polyallyl compound and a propane oligomer, preferably a tetramer, are added to a polymerization reactor. The rheological properties can be improved by using a propylene oligomer.

In patent application JP 51059987, vinyl chloride is polymerized to reduce the amount of fish eyes that appear in the polymer in the presence of low molecular weight polyethylene and alkane and / or fatty acid esters.

According to the invention, it has been observed that improved homo- or copolymers of vinyl chloride are obtained if the polymer contains α-olefins with a longer carbon chain than oligomers. Thus, the homo- or copolymer of vinyl chloride of the invention is characterized in that it contains 0.01-50% by weight of the oligomer C ₄ -C ₂₀ α-olefin or internal olefin or mixtures thereof.

In the vinyl chloride polymer of the invention, the α-olefin oligomer apparently acts as an internal lubricant that reduces or eliminates the need to use other lubricants or lubricants commonly used.

The oligomer can be added to the polymerization reactor before the polymerization begins or later during the polymerization or after the polymerization reaction. For some applications, the oligomer may also be added to the final polymer by mixing, where it acts as a conventional lubricant.

When the oligomer in terms of ozum is added vinyl chloride polymer to the polymerization reactor during polymerization, it is easily dispersed uniformly in the polymer. This gives the product good performance and processing of polyvinyl chloride is possible without the addition of other lubricants or reduces the need for other lubricants. The need for other additives is also less and the mechanical properties of the pebbles are better than those of PVC prepared in the usual way. The polyvinyl chloride prepared according to the invention can be used for the same uses as the one prepared by conventional methods.

According to the present invention, the oligomer in the homo- or copolymer of vinyl chloride can be prepared from C 1 -C 4 -alpha-olefins or internal olefins or mixtures thereof. Thus, olefins are butenes, pentenes, hexenes, octenes, heptenes, decenes, etc .. Particularly suitable are C _g -C ₁₄ α-olefms and are particularly suitable decenes such as 1-decene, 1-dodecene, 1-hexadecene and 1-tetradecene.

The oligomer to be used in the polymers of the invention may be a dimer, trimmer, tetramer, pentamer or hexamer, or a mixture thereof, i.e., the carbon chain length may be preferably in the C 1 -C 6 range. The oligomers may contain reactive double bonds or may be hydrated. The use of the polymer is determined by the most suitable oligomemic type.

The polymerization is carried out using any conventional vinyl chloride polymerization process, but most commonly using suspension polymerization. The polymerization is carried out as a batch process in a reactor equipped with an agitator, and the contents of this reactor can be heated or cooled with water flowing in the reactor shell. The content of the polymerization mixture is typically as follows: 120200 parts by weight of water, 100 parts by weight of vinyl chloride monomer, 0.05 - 0.15 parts by weight of suspending agent and 0.03-0.07 parts by weight of vinyl chloride soluble initiator. Air was sucked out of the reactor containing components other than the monomer and vinyl chloride was added to the mixture. Due to its effective mixing, it is distributed into water as small droplets, whose diameter is 50 -150 μ-m. Suspending an agent such as polyvinyl alcohol stabilizes the mixture. The polymerization begins in monomial droplets when the temperature is increased to 50 ° C and then the temperature is adjusted to the desired value (5075 ° C). Transfer the batch to tanks for gas removal and expulsion. The remaining monomer is removed from the polymer particles by vapor expulsion. The mixture is centrifuged and the solid polymer is usually dried using a fluidized bed or drum process.

The molar mass of PVC is adjusted using polymerization temperature. As the temperature rises, the size of the polymer molecules decreases.

Similarly, particle porosity depends on temperature; as the temperature rises, the porosity decreases.

As initiators in the polymerization of vinyl chloride, azo ah peroxy compounds such as dicetyl peroxides, peroxide carbonates, alkyl peroxide esters or azodi-isobutyl nitrile are used. The degree of polymerization depends on the initiator. E.g. lauryl peroxide and azodiisobutylnitrile can best be used at higher polymerization temperatures, while easily degradable compounds such as acetyl cyclohexyl sulfonyl peroxide or di-2-ethylhexyl peroxide carbonate can be used at lower temperatures. In many cases, it is preferable to use a mixture of the two initiates. The total polymerization time is usually 4-10 hours.

Polyvinyl alcohol or cellulose derivatives such as methyl-, hydroxyethyl-, hydroxypropyl methyl- or hydroxypropyl cellulose or mixtures thereof are used as the suspending (dispersing) agent. A portion of the dispersant is often added later during polymerization.

Hydrochloric acid formed from vinyl chloride during polymerization, as well as acids formed from certain initiates, is neutralized with bases or buffer compounds such as sodium or magnesium hydroxide or carbonate.

The necessary additives are mixed with the polymer before processing.

The following non-limiting examples are shown to illustrate the invention.

Laboratory-scale polymerizations were performed in an autoclave-type polymerization reactor. Standard procedures were used for analyzing: volume mass: ISO R 60, viscosity number and K value: ISO R 174 and plasticizer absorption (DOP): ISO 4608.

Examples 1-4

To the polymerization reactor was added 10 kg of vinyl chloride monomer (VCM), 12 kg of water and 0.57 g of polyvinyl alcohol / kg of VCM as a dispersing agent. 0.7 g of dispersion agent / kg VCM was added during polymerization. Dicetyl peroxide carbonate is used as the initiator. The oligomer was added to the polymerization reactor at the beginning of the polymerization. As the oligomer, we use the decene oligomer containing double bonds, and this oligomer mainly contains a trimmer (C ^) and a tetramer (C ₄₀ ). The polymerization temperature is 57 ° C. The polymerization tests are shown in Table 1.

Table 1. Polymerizations

Example Oligomer g / kg VCM The initiator g / kg VCM Conversion % All the time polymerization, min 1 10 2.0 69.6 251 2 20 2.0 57,3 357 3 35 2.5 45,1 426 4 100 2.5 56.5 779

The properties of the polymer are shown in Table 2.

Table 2. Resin assays

Example Volume mass gA Granule size D50, / xm K value Viscosity DOP % 1 575 170 66,3 110 20 2 586 134 65,3 107 18 3 549 139 62,6 97.0 19.7 4 464 129 54.6 72.6 26,8

Examples 5 and 6

The polymerisations are carried out in a similar manner, but as the oligomer we use the hydrated decen oligomer, which mostly contains a tetramer (C ₄₀ ), but also a trimer (C ^) and a pentamer (C ₅₀ ). The amount of initiator used is 1.25 g / kg VCM. The polymerizations are shown in Table 3 and the resin analyzes in Table 4.

Table 3. Polymerizations

Example Oligomer g / kg VCM Conversion % Polymerization time min 5 10 67.6 261 6 15 59,0 255

Table 4. Resin assays

Example Volume mass g / i Granule size D50, μια DOP % 5 557 178 20,7 6 565 162 20.5

Examples 7-9

1450 g of vinyl chloride and 1740 g of water are dosed into the autoclave type of polymerization reactor. The polyvinyl alcohol dispersant is used together with 1.5 g / kg VCM. The initiator is dicetyl peroxide carbonate. The oligomer is a hydrated decen oligomer containing most of the tetramer (C ₄₀ ) and pentamer (C ₅₀ ). The polymerization conditions are shown in Table 5 and the resin analyzes in Table 6. Such polyvinyl chloride containing a large amount of oligomer can be used e.g. with a mixing device to adjust the lubrication rate of conventional PVC or PVC containing a low amount of oligomer.

Table 5. Polymerizations

Example Oligomer g / kg VCM The initiator g / kg VCM Conversion % All the time polymerization, min 7 200 1.8 88.5 305 8 300 1.8 84.1 480 9 500 1.5 78,7 480

Table 6. Resin assays

Example Volume mass g / i Granule size D50, μ, τα. DOP % 7 558 125 15.8 8 545 166 16.9 9 470 199 20.5

Examples 10 -14

The resins obtained in the polymerizations are prepared as stabilized mixtures. In all cases, 100 parts by weight of polyvinyl chloride, 1 part by weight of lead sulfate and 0.2 parts by weight of stearic acid were used. Thermal stability (Congo red) is determined according to the ISO R 182 procedure and the VICAT softening point using the ISO R 306 standard. MS pressure refers to a gelling test performed using a Maclow-Smith thermometer. The results are shown in Table 7.

Table 7. Properties of mixtures

Example Quantity oligomers g / kgVCM MS pressure kg / cm ² Congo red s VICAT ° c 10 - 182 100 84 11 10 161 180 79 12 20 110 180 78.5 13 30 100 210 77 14 100 42 280 76.5

The results clearly show that the addition of oligomers significantly improves thermal stability. The lubricating properties of the oligomer can be seen from MS pressure, i.e. the processing properties are better than with conventional PVC.

Examples 15 -19

13 kg of vinyl chloride monomer (VCM), 15.6 kg of water and a total of 1.4 kg of polyvinyl alcohol / kg of VCM are added to the polymerization reactor. Dicetyl peroxide carbonate 1.3 g / kg VCM was used as the initiator. The oligomer used is a hydrated decade oligomer containing tetramers (C ₄₀ ), pentamers (C ₅₀ ) and heptamers (C ^).

Add the oligomer:

Example 15: in the beginning of the polymerization reaction Example 16: during the reaction, 40 min after the start Example 17: during the reaction, before the release of pressure Example 18: to the suspension, after removal of the gas Example 19: reference, without oligomer

Table 8. Resin polymerizations and analyzes

Example Conversion % Polymerization time, min Volumska mass, g / l Size granules, / im DOP % 15 90 261 574 179 21.6 16 91 261 577 182 20.9 17 88 282 573 180 19,1 18 88 278 559 192 21.5 19 88 278 552 190 22.3

Example 20

The polymerization is carried out in the same manner as in Example 15, except that the oligomer used is made from a mixture of internal olefin containing 90% C ₁₅ olefin and 10% C ₁₆ olefin. The oligomer contains 48% dimers, 39% trimers and 13% tetramers. The polymerization results are:

Conversion 91 % Polymerization time 342 min Volume mass 548 Vkg Granule size, D50 182 / xm Softener absorption 20,8 %

For

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Claims (9)

1. Homo- or copolymer of vinyl chloride, characterized in that it contains 0.01 - 50% of the oligomer α-olefin or internal olefin or mixtures thereof. A polymer according to claim 1, characterized in that the oligomer is an oligomer C _{g 14} α-olefin. Polymer according to claim 1 or 2, characterized in that the oligomer contains dimers, trimers, tetramers, pentamers or hexamers or mixtures thereof. Polymer according to any one of the preceding claims, characterized in that the oligomer contains double bonds. 5. Polymer according to claim 4, characterized in that the double bonds of the oligomer are hydrated. Polymer according to any one of the preceding claims, characterized in that the polymer is prepared by the suspension polymerization process. Polymer according to any one of the preceding claims, characterized in that the oligomer is added to the polymerization reactor at the beginning of the polymerization or during polymerization. A polymer according to any one of claims 1-6, characterized in that the oligomer is added after polymerization. A polymer according to any one of the preceding claims, characterized in that α-olefin is 1-decene.