JPS60133041A - Ethylene-vinyl acetate copolymer composition - Google Patents

Abstract

PURPOSE:To obtain titled composition of improved heat resistance without impairing the characteristics inherent in EVA, by incorporating EVA with a polymer derived from graft polymerization of an EVA-vinyl chloride system while being kept in a swelled state without dissolving the former in the latter. CONSTITUTION:The objective composition can be obtained by incorporating a blend of (A) 100pts.wt. of ethylene-vinyl acetate copolymer (EVA) with a vinyl acetate content 1-50wt% and (B) 100pts.wt. of another EVA with a vinyl acetate content 1-60(pref. 20-60)wt% with (C) 1-100(pref. 10-90)pts.wt. of a polymer derived from suspension graft polymerization of 5-200pts.wt. of vinyl chloride or a monomer mixture consisting mainly of the same in an aqueous medium while being kept in a swelled state without dissolving the same kinds of EVAs mentioned above in said monomer (mixture).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition (hereinafter abbreviated as BVA), and particularly to a composition with improved heat resistance and tensile strength of EVA.

Due to its excellent flexibility, processability, transparency, etc., EVA is widely used in the form of films and sheets, and is also applied as a raw material for hot melt adhesives and foamed products. However, since ethylene copolymers generally have poor heat resistance, it has been a long-standing technical challenge to improve heat resistance and increase the operating temperature without sacrificing the above-mentioned excellent properties.

One way to increase the heat resistance of EVA is to crosslink it. That is, 1CVA is mixed with an appropriate radical generator and crosslinked by heating.
This is a method to reduce thermal deformation at high temperatures. This method is
Although it is possible to improve the heat resistance of EVA without significantly impairing its flexibility and transparency, it is necessary to remove crosslinking after molding, which limits the applicable processing methods to only a few methods. There is. Furthermore, there is also the problem that the crosslinking reaction is complicated because it requires a high temperature and a long time.

Other ways to improve the heat resistance of BVA include mixing inorganic materials or glasstics with high heat resistance, but mixing these materials poses problems in terms of miscibility with EVA. EVA
No good material has been found so far because the good flexibility, transparency, processability, etc. of

As a result of intensive research into methods for increasing the heat resistance of EVA, the present inventors have developed a polymer obtained by graft polymerizing vinyl chloride to EVA without dissolving the EVA in the vinyl chloride and leaving it in a swollen state. By mixing with E V A, E
The present invention was achieved by discovering that heat resistance can be improved without impairing the good quality of VA. That is, the present invention provides (a) vinyl acetate-containing E of 1 to 50 commercially
100 parts by weight of VA and (b) vinyl acetate containing i1-603
The EVA is kept in a swollen state without being dissolved in vinyl chloride or a hexamer mixture mainly composed of vinyl chloride (hereinafter abbreviated as vinyl chloride, etc.), and the agglomerated vinyl in an aqueous medium is added to A small polymer obtained by suspension graft polymerization of 5 to 200 vertical axis parts (hereinafter referred to as B
VA, /VC graftomer) is a +6 VA composition consisting of 1 to 100 parts by weight.

The present invention will be explained in more detail below.

EV of 1 to 50 cm containing vinyl acetate used in the present invention
As A, those produced by a commonly commercially available high-pressure radical polymerization method can be used.

On the other hand, the E For example,
16346, Japanese Patent Application Laid-Open No. 53-97088, and Japanese Patent Application No. 58-91594 can be used. Polymers produced by kraft polymerization by dissolving EVA in vinyl chloride, etc. and suspending them in an aqueous medium not only do not have good transparency by themselves, but also have poor transparency when mixed with EVA. The transparency of the resulting composition deteriorates, making it impossible to obtain the effects of the present invention.

The EVA contained in the EVA/VC graftomer may be one containing vinyl acetate, preferably 1 to 60 densities, preferably 20 to 60 densities, and may be produced by high-pressure radical polymerization, emulsion polymerization, or solution polymerization. Commercially available EVA manufactured by et al. can be used. If the vinyl acetate content in BVA contained in the BVA/VC graftomer is less than 1 tl, the transparency of the composition obtained by mixing with EVA will be extremely poor, and the properties of EVA will be impaired, resulting in a light weight It's so cool.

In addition, when the vinyl acetate content exceeds 60% by weight: V
This is undesirable because the flexibility of the A/VC graftomer is significantly reduced, and handling of the EVA becomes troublesome.

When producing the EVA/VC graftomer, the comonomer used with vinyl chloride may be any monomer that polymerizes with a radical initiator, such as ethylene,
Examples include olefins such as propylene, styrene, vinyl monomers such as methyl methacrylate, vinyl acetate, vinylidene chloride, maleic anhydride, and the like.

These comonomers are used within a range that does not impair the effects of the present invention, but 10% by weight or less based on vinyl chloride is light.

The amount of reinforced vinyl etc. to be graft-polymerized to the above EVA is as follows:
The amount is 5 to 200 parts by weight per 100 parts by weight of EVA. If the amount of graft polymerization is less than 5 okitanbu, the heat resistance of the composition obtained by mixing with EVA will not be sufficiently improved, which is not preferable. When the amount of graft polymerization exceeds 200 parts by weight, the obtained EVA/VC graftomer and the EVA described below
This makes it difficult to blend evenly.

In the composition of the present invention, E V A 100 gi1
The amount of EVA/VC graftomer blended in part ii is:
The amount is 1 to 100 parts by weight, preferably 10 to 90 parts by weight. If the blending amount is less than 1 part by weight, the heat resistance of EVA cannot be sufficiently improved, and if it exceeds 100 parts by weight, the fluidity during processing deteriorates, significantly impairing the original characteristics of gVA. So it's not light or heavy.

Depending on the intended use, the composition of the present invention may contain EvA, stabilizers, lubricants, processing aids, and small amounts of plasticizers that are commonly added to vinyl chloride resins.

Mixing of these components can be easily carried out using a known method such as a Banbury mixer, a two-roll machine, or an extruder. EVA and EVA/VC graftomer can be mixed by putting them into a mixer at the same time, but EVA/V
Depending on the amount of C graftomer and i'i V A cage, it may be better to knead the EVA/■C graftomer with a stabilizer, etc. in advance, gel it sufficiently, and then add EVA and mix. be.

The composition of the present invention mixed in this manner not only has excellent transparency and flexibility, but also has excellent mechanical properties such as tensile strength, and has excellent fluidity during processing, so it has improved heat resistance. It can be expected to be used in a wide range of applications as EVA. .

Hereinafter, the present invention will be specifically explained with reference to Examples. In addition, physical property measurements in the following examples were performed as follows.

A combination E V A/V C Graftomer 100 parts I Organotin stabilizer: TVS #8831 (Nitto Kasei product) 2 #Lubricant: WaxOP (Hoechst product) 1 EVA specified ratio B of the measurement sample Preparation After mixing each component in the above-mentioned proportions, roll kneading was carried out at 130°C for 10 minutes, and then pressed at 150°C and a pressure of 1ooK4/i to prepare a sheet If.

C Physical property evaluation method Tensile Crab JISK6723 (K4/I-#Rigid elongation:
Same as above (Break point, Ch) Light transmittance: JIS K6714 (%) Torsional rigidity: JIS K6745 (V4/ctI) Melt index (MI): ASTMIN23B-75 (v/1o min) Heat resistance
2 Roll-pressed sheets with a length of 5 crn1
It was cut into pieces with a width of 16nm and a thickness of 4m and left in an oven maintained at 180°C for 30 minutes to check the degree of deformation. A is one that has a length of 46n or more and retains a tanzaku-shaped shape.
, Those that were not melted but had a length of less than IQ71 or did not retain their tanzaku shape were B1 melted, and those that retained their original shape and were the best were designated as C.

Reference example 1 Production of EVA/VC graftomer 4 parts pure water in 1 container made of 701 stainless steel vinyl chloride equipped with a stirring device
0 to 9, EVA (manufactured by Toyo Soda Kogyo ■, Ultrasen 75
0, vinyl acetate content is 32% by weight) 5 to 9. 15v of 2-mercaptoethanol as a chain transfer agent, 50v of partially saponified polyvinyl acetate as a suspending agent, and after closing the lid and purging with nitrogen, vacuum was applied to dissolve the vinyl chloride monomer.
．． 5 K9 was introduced.

Start raising the temperature without stirring, and when it reaches 60℃, 2.2
'-Azobis-2,4-dimethylvaleroni) IJle 5
v was added to start polymerization. Pressure 5 Ky/ct
Polymerization was carried out for 6 hours while introducing vinyl chloride monomer so as to keep the EVA 81. Off
An EvA/vC graftomer containing 4'% was obtained (abbreviated as graftomer ■). Similarly, Ultracene 750 was converted to 72.031 without using 2-mercaptoethanol.
EVA/VC graftomer containing J-3ii-% (abbreviated as graftomer=II) and EVA/V containing 453 double sweetened Ultracene 722 (vinyl acetate content 28% by weight)
Produce C graftomer (abbreviated as graftomer■),
It was used in the following examples.

Reference Example 2 Production of EVA/VC graftomer by dissolution method In a 701 stainless steel vinyl chloride polymerization vessel equipped with a stirring device, 27 Kf of pure water and EvA (manufactured by Toyo Soda Kogyo ■, Ultrasen 750, vinyl acetate content: 52% precious) were added. q
, o Kg, partially saponified polyvinyl acetate 502 was charged, the lid was closed, the atmosphere was replaced with nitrogen, and then vacuum was applied and 9 was introduced into the vinyl chloride monomer 9.0. The temperature was started to increase without stirring, and FiVA was dissolved in the vinyl chloride monomer at 60C for 3 hours.

Next, 5v of 2,2'-azobis-2,4-dimethylvaleroni) IJ was added to start polymerization, and the polymerization was carried out for 8 hours to produce IThVA containing 62.5% by weight of VA.
/VC Craftomer was obtained (abbreviated as Graftomer B)
.

Example 1 Ultracene 664 (vinyl acetate content = 26% by weight) 7
5v and the graftomer I25S' produced in Reference Example 1 were blended, and various properties were measured. The results are shown in Table 1 along with the properties of Ultracene 634.

Comparative Example 1 Graftomer B produced as shown in Reference Example 2 was used in place of the graftomer ① in Example 1, and the properties were measured in the same manner as in Example 1 and are shown in Table 1.

As is clear from Table 1, the composition of the present invention has superior tensile strength and heat resistance compared to EVA, and does not impair transparency, flexibility, or fluidity.
It can be seen that transparency and flexibility are impaired when VA/VC graftomer is used.

Examples 2 to 7 Types of Ultracene and B V produced in Reference Example 1
A/VC graftomers were blended with different types and mixing ratios, and various properties were measured.

The results are shown in Table 2 along with the properties of Ultracene used.

Claims (1)

[Claims] (1) (a) 100 parts by weight of an ethylene-vinyl acetate copolymer with a vinyl acetate content of 1 to 50% by weight;
The ethylene-vinyl acetate copolymer is maintained in a swollen state without being dissolved in vinyl chloride or a monomer mixture mainly composed of vinyl chloride in an aqueous medium in an aqueous medium. 5~
An ethylene-vinyl acetate copolymer composition comprising 1 to 100 parts by weight of a polymer obtained by suspension graft polymerization of 200 parts by weight.