KR900003911B1 - Anti-impactness and high intensity polychloride vinyl resin - Google Patents

Abstract

Anti-impact high intensity PVC resin is prepd. by graft copolymerizing (A) vinyl chloride monomer alone, or the mixt. comprising of vinyl chloride monomer and acrylic acid or methacrylic acid ester monomer of C1-18 primary alcohol; with (B) atactic polypropylene (APP). The APP has ave. Mw of 1000-30000 and is a byproduct in the isotactic polyupropylene (IPP) prodn.. The VCM alone is used in amt. of 2.0-2000 times wt. w.r.t. the APP, or the acrylic acid or methacrylic acid ester monomer is used in amt. of 2.20 wt.% w.r.t. VCM.

Description

Method for producing high impact polyvinyl chloride resin

The present invention relates to a method for producing an impact resistant high strength polyvinyl chloride resin for improving polyvinyl chloride resin (PVC) physical properties.

To explain this in detail, impact modifiers such as chlorinated polyethylene (CPE), methyl methacrylate-butadiene-styrene (MBS), acrylonitrile-butadiene rubber (NBR), urethane rubber (PUR), etc. The present invention relates to a method for producing a PVC resin having excellent mechanical strength, impact resistance and excellent process formability even if no additive is added.

PVC has a mechanical modifier due to stiffness of molecular movement due to chlorine atom, but it has excellent mechanical properties, but it must be added to a rubber modifier for applications that are too hard and require impact resistance. However, these modified PVC products have the drawback of lowering the mechanical strength such as tensile strength and modulus due to the addition of the modifier and increasing the product cost due to the expensive modifier.

These drawbacks required the development of impact-resistant high strength PVC resins by chemical reactions, not by external modifiers.

The impact-resistant high strength PVC resin developed on the background of this is an APP obtained by graft polymerization of vinyl chloride unit (VCM) on amorphous and flexible atactic polypropylene (APP) which is a by-product of isotactic polypropylene (IPP) production. -PVC graft copolymer resin. This graft copolymer resin imparts impact resistance to hard PVC resins by providing a soft polymer chain of the medium molecule APP chain, and can further improve the physical properties caused by the addition of external modifiers. However, rubbers, except for APP, could not obtain good physical properties because the solubility was a problem and the impact resistance was required by the chemical reaction method.

In this regard, methods for graft copolymerization of VCM on various rubbers have been published to preserve the mechanical strength in PVC resins and to improve impact resistance. These rubbers are more expensive than APP and have problems in economical efficiency. PVC graft copolymers were less reactive than APP-PVC graft copolymers, and thus exhibited poor impact resistance.

Meanwhile, additive methods for improving impact resistance of PVC resins have been developed and are still in use. However, as the amount of additives increases, the tensile strength and modulus decrease, and there is a problem in compatibility due to the addition of external additives. There is a flaw.

It is an object of the present invention to graft copolymerize a mixture of monomers mainly composed of VCM to APP of heavy molecules produced as by-products during IPP manufacturing to make PVC resins for impact resistance, and without much lowering the mechanical properties such as tensile strength and modulus. To achieve mechanical resistance and impact resistance.

This object is achieved by graft copolymerization of a mixture of vinyl units, predominantly VCM, in pure medium molecule APP.

The present invention will be described in more detail. By selecting and extracting APP, which is a by-product of an IPP manufacturing plant, as a solvent of ethers, only pure APP is obtained, dissolved in a vinyl body mainly composed of VCM, polymerized by adding a radical initiator, and excellent in mechanical strength and impact resistance. Method for preparing an APP-PVC graft copolymer.

APP used in the present invention has an average molecular weight of 1000 to 30000 and is 0.5 to 30% by weight of the composition of the produced copolymer. If APP content is less than 0.5% by weight, there is little change in physical properties. If it exceeds 30% by weight, the cross-linking degree of APP-VCM graft copolymer is large, making it impossible to process. If the molecular weight of APP is 30,000 or more, the mechanical strength of the graft copolymer increases, but the solubility is poor, resulting in side reactions such as keto-allyl structure, resulting in poor thermal stability. The strength is reduced.

In the present invention, the VCM to be grafted to the APP may be added at a weight ratio of 2.0 to 200 times with respect to the APP. In other words, when the amount of VCM is increased, the flexibility of the obtained graft copolymer decreases, and instead, the tensile strength is increased. However, in this case, if the VCM is maintained at 2.0 times or less, the solubility is low, resulting in a non-uniform reaction, and crosslinking by APP also occurs, resulting in a partially crosslinked PVC resin, resulting in a gel (Gel) fraction, resulting in poor solubility and processability. Therefore, the APP-PVC graft copolymer is made hard by grafting a lot of VCM. In order to obtain a soft APP-PVC graft copolymer having a VCM content of less than 2.0 times, the amount of solvent is particularly large and the graph is grafted in a uniform dilution solution. Must be copolymerized.

The main vinyl units used in the present invention are vinyl chloride units (VCM), and vinylidene chloride units (VDCM), acrylonitrile units (ANM), etc., are used to increase the strength as the second vinyl units. To increase, acrylic acid or methacrylic acid esters of monohydric alcohols having 1 to 18 carbon atoms may be used, for example ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, methyl acrylate, cyclo Acrylic acid ester such as hexyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, lauryl acrylate, palmityl acrylate, oleyl acrylate, stearyl acrylate, decyl acrylate And methyl methacrylate, ethyl methacrylate, mn-propyl methacrylate, isopropyl methacrylate Methacrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, oleyl methacrylate, n-octyl methacrylate , Lauryl methacrylate, palmityl methacrylate, stearyl methacrylate, decyl methacrylate and the like. It is preferable to add 2 to 20 wt% of VCM, but less than 2 wt% does not affect plasticity improvement of APP-PVC graft polymer. If it exceeds 20 wt%, mechanical properties such as tensile strength and modulus will be degraded. . That is, graft polymerization of APP alone or in combination with vinyl units giving plasticity results in graft polymers having different impact resistance and fluidity depending on the composition and content of the monomers used.

Since the method of the present invention is radical graft polymerization, benzoyl peroxide, metadichlorobenzoyl, methyl ethyl ketone peroxide, cumene hydroperoxide, di-t-butyl peroxide, diisopropyl carbonate, sodium persulfate and potassium persulfate are used as radical initiators. Peroxide initiators such as ammonium persulfate and azo radical initiators such as bisazisoisovaleronitrile can be used, but among these catalysts, peroxides react easily with the APP polymer molecule to easily liberate hydrogen proton radicals, making the graft reaction point easier. System catalysts are more useful.

The method of the present invention is radical graft polymerization. The polymerization method may be any of suspension polymerization, emulsion polymerization, solution polymerization and bulk polymerization, but is particularly useful industrially for suspension polymerization and emulsion polymerization. As the suspending agent in the suspension polymerization of the present invention, methylcellulose, partially plasticized polyvinyl alcohol, polyvinylpyrrolidone or a mixture thereof is used. The usage-amount is 0.01-4.0 weight% with respect to the obtained graft polymer, and 0.1-2.0 weight% is especially preferable. The emulsifier for emulsion polymerization may be added 0.1 to 2.0% by weight of a surfactant such as sodium lauryl acid or dodecylbenzenesulfonate, or an ethylene oxide nonionic surfactant.

Since emulsion polymerization and suspension polymerization are performed in aqueous dispersion, graft polymerization takes place in aqueous dispersion, and the ratio of water and organic matter is preferably 0.5 to 15% by weight. If less than 0.5 weight ratio of water is added, the viscosity becomes too high to obtain a uniform dispersion, and if more than 15 weight ratio is added, the productivity is lowered and the water is heated too much, resulting in excessive energy consumption.

The temperature of the graft polymerization reaction of the method of the present invention is suitable to 40 ~ 80 ℃ as in the normal radical initiation polymerization, the exact reaction temperature will vary slightly depending on the decomposition temperature and half-life of the radical initiator and the mechanism of the graft copolymerization reaction.

The APP-PVC graft polymer obtained according to the present invention described above satisfies both tensile strength and impact resistance at the same time, so that a pipe or sheet requiring high strength and impact resistance without adding CPE, MBS, NBR, PUR, etc. It can be used for products such as corrugated paper, and because the tensile strength of VCM is higher than that of a single polymerized PVC resin at the same temperature, more impact-resistant supplements can be mixed while maintaining the strength, so that impact reinforcing materials such as CPE, MBS, NBR, and PUR When added, the impact resistance is greatly increased. In addition, all of the impact modifiers for mixing are expensive, but the APP modifier is a by-product of the IPP plant, which is used as a raw material for some adhesives and as a plasticizer, but has an advantage of being inexpensive compared to the mixing modifiers. In addition, since these graft polymers are chemical reactions, they are homogeneous and unlike other impact modifiers for mixing with PVC, which increases their compatibility with homopolymerized PVC resins. . In addition, the polymerization method may be any of suspension polymerization, emulsion polymerization, solution polymerization, and bulk polymerization, and has the advantage of using the existing polymerizer as it is in the case of suspension polymerization which is applied to the production of PVC homopolymer on a large scale.

Now, the suspension polymerization method of the present invention will be described. In a high pressure reactor equipped with a stirrer, a predetermined amount of water, APP, initiator, VCM, the second vinyl unit and the suspending agent are added and stirred at room temperature to obtain a uniform aqueous dispersion, and then heated to raise the temperature to 40 to 80 ℃. The polymerization is continued while heating and stirring at this polymerization temperature for 3 to 20 hours. After the polymerization is completed, the reaction contents may be filtered or centrifuged to separate and graft the polymer. In the case of emulsion polymerization, an emulsifier may be added instead of a suspending agent in the above-described method, and a water-soluble initiator may be added as an initiator. In the case of emulsion polymerization, spray drying or conventional sedimentation may be used to separate the graft polymer instead of filtration or centrifugation.

The implementation method will be described in detail through the following examples. However, the contents of the present invention are not limited to these examples.

[Examples 1-16, Comparative Examples 1-9]

Purified atactic polypropylene (APP), vinyl chloride unit (VCM) and acryl unit were added to a high pressure reactor equipped with a stirrer, and 0.3 wt% of benzoyl peroxide (BPO) was used as a polymerization initiator. The number (α value) was 2.0 and 2% methylcellulose was used as a dispersant.

After the polymerization reaction was stirred for 30 minutes, the reaction temperature was raised to 60 ° C., and the polymerization reaction product produced by polymerization for 10 hours was filtered and washed with a sieve of 150 to 250 mesh, and the resultant was air-dried at 40 ° C. for 10 hours. White graft copolymers were obtained as examples and comparative examples with the composition as shown in Fig. 2.

Organometal stabilizers are mixed with these graft copolymer resins and kneaded at 170 ° C. for 10 minutes to prepare test pieces of each composition, and properties such as tensile strength, modulus and elongation, impact strength and hardness as shown in Tables 3 and 4 are shown. Obtained in comparison with the comparative examples showed a relatively good physical properties.

TABLE 1

* Chlorinated polyethylene uses 36% by weight of chlorine.

TABLE 2

TABLE 3

1) ASTM D638

2) Izod, Notched (ASTM D256)

3) Hardness Shore D

TABLE 4

1) ASTM D638

2) Izod, Notched (ASTM D256)

3) Hardness Shore D

Claims (2)

To prepare a shock-resistant high-strength polyvinyl chloride resin obtained by graft copolymerization of vinyl chloride units alone or various mixtures of acrylic acid or methacrylic acid ester units of monohydric alcohols having 1 to 18 carbon atoms and vinyl chloride units with APP Way. APP is a by-product of the IPP plant, which is selectively extracted and purified on ethers, and has an average molecular weight of 1000 to 30000. The vinyl chloride unit alone uses a weight ratio of 2.0 to 2000 times with respect to APP, or has 1 to 1 carbon atoms. The method of Claim 1 which uses together 2-20 weight% of acrylic acid or methacrylic acid ester units of 18 monohydric alcohols with respect to a vinyl chloride unit.