TWI759819B - Polyvinyl alcohol and protective solution and polyvinyl acetate emulsion comprising the same - Google Patents

Abstract

The instant disclosure relates to a polyvinyl alcohol (PVA) and a protective solution and polyvinyl acetate emulsion comprising the same. The polyvinyl alcohol having a ratio (B) = g ⁽²⁾-1(τ=100μs) / g ⁽²⁾-1(τ = 0.5 μs), which is obtained by measuring 6.4 wt% PVA solution via dynamic light scattering (DLS) analyzer, wherein the range of the ratio (B) is 0 ＜ (B) ＜ 0.38. The PVA of the present invention can have better protective colloid effect, can reduce the amount of PVA used, and has a more stable emulsion viscosity.

Description

Polyvinyl alcohol and protective solutions and polyvinyl acetate emulsions containing the same

The present invention relates to a block polymer suitable as a dispersant for protective colloid solutions, in particular a polyvinyl alcohol as a protective colloid, and protective solutions and emulsions containing the same.

Polyvinyl alcohol (POLYVINYL ALCOHOL, PVA) is a white or slightly yellow granular or powdery substance, which is a stable, non-toxic water-soluble polymer. Polyvinyl alcohol has good film-forming properties, and the formed film has excellent adhesion, solvent resistance, abrasion resistance, tensile strength and oxygen barrier properties, etc., so it is widely used in product applications, such as: warp yarn sizing agent , resin finishing and processing, temporary adhesives for printing machines, and protective colloids and suspension stabilizers for latexes such as polyvinyl acetate (PVAc), polyvinyl chloride (PVC), and polystyrene (PS).

Polyvinyl alcohol has both hydrophilic and hydrophobic functional groups, so polyvinyl alcohol has the properties of interfacial activity, so it can be used as a protective colloid for polymer emulsification and suspension polymerization, which can delay or prevent particles in liquid-repellent dispersions. aggregation. Suspension polymerization usually involves dispersing a target monomer (eg, PVAc, PVC or PS, etc.) in an aqueous medium in the presence of polyvinyl alcohol as a dispersant. The properties of polyvinyl alcohol have a considerable impact on the quality of the product made from the target monomer, such as whether PVC can produce the desired particle size and particle size distribution, or whether PVAc can produce the required emulsion viscosity and viscosity stability Wait.

When analyzing the conventional polyvinyl alcohol aqueous solution by dynamic light scattering particle size analyzer (DLS), it was observed that some polyvinyl alcohol molecular chains will aggregate, and this aggregation phenomenon will reduce the characteristics of the emulsion .

The present invention finds that whether polyvinyl alcohol produces larger particle aggregation in aqueous solution is related to the block length and branching degree, and this aggregation phenomenon will further affect the emulsion stability and protective colloid. Therefore, the present invention obtains polyvinyl alcohol with high protective colloid properties by controlling the polyvinyl alcohol polymer and the alkalizing conditions so that the polyvinyl alcohol has a specific particle size ratio range.

In view of this, the main purpose of the present invention is to provide a polyvinyl alcohol, characterized in that, the polyvinyl alcohol has a ratio (B), the ratio (B)=g ⁽²⁾ -1(τ=100μs)/g ⁽²⁾ -1(τ = 0.5 μs), g ⁽²⁾ is the autocorrelation function at the selected angle, τ is the delay time, I is the signal strength, derived from g ^2(q;τ) = {I( q,t)I(q,t+τ)}/{I(q,t)} ² , q is the scattering vector and t is the time, which is determined by dynamic light scattering (DLS) ) measured in 6.4 wt% polyvinyl alcohol solution, wherein the ratio (B) is in the range of 0 < (B) < 0.38.

In a preferred embodiment, the polyvinyl alcohol further has a block index (η), and the block index (η) is in the range of 0.4 < η < 1.

In a preferred embodiment, the polyvinyl alcohol further has a 4% aqueous solution transparency (%), and the 4% aqueous solution transparency (%) is greater than 98%.

In a preferred embodiment, the polyvinyl alcohol further has a branching index (BI), and the branching index (BI) ≦ 0.9.

In a preferred embodiment, the polyvinyl alcohol further has a number-average molecular weight (Mn) analyzed by water-phase GPC, and the number-average molecular weight (Mn) ≤ 12800.

In a preferred embodiment, the polyvinyl alcohol further has a degree of hydrolysis, and the degree of hydrolysis ranges from 86 to 89 mole%.

In a preferred embodiment, the polyvinyl alcohol further has a crystallization temperature (Tc), and the crystallization temperature (Tc) ranges from 135°C to 138°C.

Another object of the present invention is to provide a protective solution characterized in that it comprises the aforementioned polyvinyl alcohol as a dispersant.

Another object of the present invention is to provide a polyvinyl acetate emulsion, which is characterized in that the polyvinyl acetate emulsion is synthesized through the aforementioned protective solution.

In a preferred embodiment, after the polyvinyl acetate emulsion is placed at 60°C for 2 months, the viscosity is measured at room temperature (25°C), and there is basically no delamination or the viscosity change value does not exceed 20,000. (cp).

In the present invention, the PVA obtained by controlling the alkalizing conditions, block length and degree of branching has a particle size ratio (B) in a specific range, and the PVA can be used as a dispersant to further obtain a stable PVA solution of protective colloid, Has suitable viscosity stability. Therefore, the PVA of the present invention can have a better protective colloid effect, can reduce the amount of polyvinyl alcohol used, and has relatively stable emulsion viscosity and other advantageous effects.

The above summary is not intended to present all embodiments or all aspects of the invention, but merely to provide examples of some of the novel aspects and features set forth herein. Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate various features of embodiments of the present invention.

The detailed description and technical content of the present invention are described below with reference to the drawings. Furthermore, the drawings in the present invention are not necessarily drawn according to the actual scale for the convenience of description, and the drawings and their proportions are not intended to limit the scope of the present invention. It should be understood that aspects of the present invention are not limited to the configurations, means and characteristics shown in the accompanying drawings, which are described in advance.

As used herein, "or" means "and/or" unless otherwise stated. Reference herein to "comprising or including" means not excluding the presence or addition of one or more other components, steps, operations and/or elements to the described components, steps, operations and/or elements. The terms "comprising", "including", "including", "including" and "having" described herein can also be substituted for each other without limitation.

"A" as used herein means that the grammatical object of the thing is one or more than one (ie, at least one). Similarly, the singular forms "a," "an," "an," and "the" described herein and within the scope of the claims include plural references.

Except in the working examples or where otherwise indicated, all numbers indicating amounts of ingredients and/or reaction conditions may in all cases be modified using the term "about", meaning within ±5% of the indicated number . As used herein, the terms "substantially free" or "substantially free" refer to less than about 2% of a particular characteristic. All elements or features expressly stated herein may be negatively excluded from the scope of the claim.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by one of ordinary skill in the art to which this invention belongs. In addition, the following terms used in this application have the following meanings.

The present invention relates to a polyvinyl alcohol, which is characterized by comprising: a ratio (B), the ratio (B)=g ⁽²⁾ -1(τ=100μs)/g ⁽²⁾ -1(τ=0.5μs ), which is obtained by measuring a 6.4 wt% polyvinyl alcohol solution by a dynamic light scattering particle size analyzer, wherein the ratio (B) is in the range of about 0<(B)<0.38.

In one aspect, the present invention provides a protective solution, which is characterized by comprising the aforementioned polyvinyl alcohol as a dispersant. On the other hand, the present invention provides a polyvinyl acetate emulsion, which is characterized in that the polyvinyl acetate emulsion is synthesized through the aforementioned protective solution.

The "dynamic light scattering particle size analyzer (DLS)" described in this paper observes the fluctuation data of scattered light intensity with time at a specific angle, as shown in Figure 1(a) and (b), while the particles are In the solvent, the Brownian motion is carried out by the collision of the solvent molecules, and the numerical value is changed. g ⁽²⁾ (τ) is the autocorrelation function at the selected angle, τ is the delay time, I is the strength of the signal, the autocorrelation function has the characteristic of decay with time, the stability of the aqueous solution is low, the slower the decay rate, the longer the decay time . The higher the stability of the aqueous solution (the smaller the degree of aggregation), the faster the decay rate and the shorter the decay time. As shown in Figure 2, the ratio of the value of g ⁽²⁾ -1 at a specific decay time range (τ=100μs) to the value of g ⁽²⁾ -1 at the beginning (τ=0.5μs) is referred to herein as The ratio (B) is an indicator of the decay rate. The smaller the ratio g ⁽²⁾ -1(τ=100μs)/g ⁽²⁾ -1(τ=0.5μs), the faster the decay rate and the higher the stability of the aqueous solution. After 100 μs, it corresponds to the contribution of the particles formed by the aggregation of multiple PVA molecular chains. In a preferred embodiment, the ratio (B) of the PVA of the present invention obtained by measuring the 6.4wt% polyvinyl alcohol solution by DLS is in the range of about 0<(B)<0.38. In a preferred embodiment, the ratio (B) of the PVA of the present invention obtained by measuring 6.4wt% polyvinyl alcohol solution by DLS, the ratio (B) is lower than 0.38, such as but not limited to: lower than 0.38, Below 0.37, Below 0.36, Below 0.35, Below 0.34, Below 0.33, Below 0.32, Below 0.31, Below 0.3, Below 0.29, Below 0.28, Below 0.27, Below 0.26, Below 0.25, below 0.24, below 0.23, below 0.22, below 0.21, below 0.2, below 0.19, below 0.18, below 0.17, below 0.16, below 0.15, below 0.14, below 0.13, Below 0.12, below 0.11, below 0.1, below 0.09, below 0.08, below 0.07, below 0.06, below 0.05, below 0.04, below 0.03, below 0.02 or below 0.01. In a preferred embodiment, the ratio (B) of the PVA of the present invention obtained by measuring 6.4wt% polyvinyl alcohol solution by DLS is in the range of about 0.1≦(B)≦0.3, such as but not limited to: 0.11 , 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, or a range between any two of the preceding values. In a preferred embodiment, the ratio (B) of the PVA of the present invention obtained by measuring 6.4wt% polyvinyl alcohol solution by DLS is about 0.11, 0.189, 0.225, 0.231, 0.254 or 0.298 .

The "polyvinyl alcohol (POLYVINYL ALCOHOL, PVA)" described in this article is a water-soluble polymer with good film-forming properties. The formed film has excellent adhesion, solvent resistance, abrasion resistance, tensile strength and Oxygen Barrier. Polyvinyl alcohol has both hydrophilic and hydrophobic functional groups, as shown in the molecular structure of the following formula (I). Therefore, polyvinyl alcohol has the property of interface activity, and can also be used as a protective colloid for polymer emulsification and suspension polymerization. .

式(I)中， O示意表示親水基結構，C示意表示疏水基結構； n表示親水基結構莫耳數，m表示疏水基結構莫耳數。

In formula (I), O represents a hydrophilic group structure, C represents a hydrophobic group structure; n represents the molar number of the hydrophilic group structure, and m represents the molar number of the hydrophobic group structure.

The "degree of alkalinity/degree of hydrolysis" mentioned herein is the degree to which the hydrophobic acetate group is substituted by the hydrophilic group, expressed as n/(n+m), where n and m are the molar number of the hydrophilic group structure in the PVA molecule and The molar number of the hydrophobic group structure, namely n and m in formula (I). The degree of alkalinity is also referred to herein as the degree of hydrolysis, and the higher the value, the higher the affinity for hydrophilic substances. The present invention finds that the degree of alkalinity can affect the aggregation of PVA molecular chains in aqueous solution. In a preferred embodiment, the range of the degree of hydrolysis of the PVA of the present invention is about 86 to 89 mole%, such as but not limited to: 86 mole%, 86.1 mole%, 86.2 mole%, 86.3 mole%, 86.4 mole%, 86.5 mole% 86.6 mole%, 86.7 mole%, 86.8 mole%, 86.9 mole%, 87 mole%, 87.1 mole%, 87.2 mole%, 87.3 mole%, 87.4 mole%, 87.5 mole%, 87.6 mole%, 87.7% , 87.8 mole%, 87.9 mole%, 88 mole%, 88.1 mole%, 88.2 mole%, 88.3 mole%, 88.4 mole%, 88.5 mole%, 88.6 mole%, 88.7 mole%, 88.8 mole%, 88.9 mole%, 89 mole% or a range between any two of the preceding values. In a preferred embodiment, the hydrolysis degree range of the PVA of the present invention is about 87 to 88 mole%, such as but not limited to: 87 mole%, 87.1 mole%, 87.15 mole%, 87.2 mole%, 87.25 mole%, 87.3 mole%, 87.35 mole%, 87.4 mole%, 87.45 mole%, 87.5 mole%, 87.555 mole%, 87.6 mole%, 87.65 mole%, 87.7 mole%, 87.75 mole%, 87.8 mole%, 87.85 mole%, 87.9 mole% %, 87.95 mole%, 88 mole%, or a range between any two of the preceding values. In a more preferred embodiment, the hydrolysis degree of the PVA of the present invention ranges from 87.09 to 87.88 mole%, such as but not limited to: 87.09 mole%, 87.17 mole%, 87.58 mole%, 87.81 mole%, 87.86 mole% or 87.88 mole% mole%.

其中，I是訊號強度。 嵌段指數 (η) ：

The "blockiness index (n)" described herein refers to the blockiness of the PVA molecule. The higher the blockiness, the longer the crystalline segment, that is, the formula (I) is schematically represented as hydrophilic. The longer the "O" of the base structure. NMR is a powerful tool for measuring the microstructure of polymers. The block index (η) described in this paper can be measured using a carbon 13 nuclear magnetic resonance apparatus ( ¹³ C NMR), and the chemical potential δ = 38~46ppm. , there are three obvious resonance peaks, from right to left are the resonance peaks of VAc-VAc, VOH-VAc, VOH-VOHdiad. The following equations ( VAc , VAc ), ( VOH , VAc ) and ( VOH , VOH ) are the area percentages of the resonance peaks of δ=39ppm, δ=42ppm and δ=45ppm, respectively. Dyad composition :

where I is the signal strength. Block index (η) :

The calculated block index (block character, η), when 0 ≦ η < 1, represents a polymer with partial block characteristics; η = 0, represents the copolymer sample is a block copolymer (block copolymer); when η =1 is a complete random copolymer; when 1<η≦2, the sample is more inclined to the structural composition of an alternate copolymer. In other words, the lower n, the higher the blockiness. The present invention finds that the degree of block can affect the aggregation of PVA molecular chains in aqueous solution. In a preferred embodiment, the range of the block index (η) of the PVA of the present invention is about 0.4 <η<1 to obtain aqueous solution stability, such as but not limited to: 0.4 <η≦ 0.95, 0.4 <η≦ 0.9, 0.4 ＜η≦ 0.85, 0.4 ＜η≦ 0.8, 0.4 ＜η≦ 0.75, 0.4 ＜η≦ 0.7, 0.4 ＜η≦ 0.65, 0.4 ＜η≦ 0.6, 0.4 ＜η≦ 0.55, 0.4 ＜η≦ 0.5, 0.45≦η＜ 1, 0.5≦η＜ 1, 0.55≦η＜ 1, 0.6≦η＜ 1, 0.65≦η＜ 1, 0.7≦η＜ 1, 0.75≦η＜ 1, 0.8≦η＜ 1, 0.85≦ η < 1, 0.9≦η < 1 or 0.95≦η < 1, η less than 0.4 will result in poor stability of the aqueous solution, and η greater than 1 will become block polymer and alternating polymer, which is not suitable for the stability control of aqueous solution . In a preferred embodiment, the range of the block index (η) of the PVA of the present invention is about 0.4 <η≦0.5; for example but not limited to: 0.401, 0.405, 0.41, 0.415, 0.42, 0.425, 0.43, 0.435 , 0.44, 0.445, 0.45, 0.455, 0.46, 0.465, 0.47, 0.475, 0.48, 0.485, 0.49, 0.495, 0.50, or a range between any two of the foregoing.

，其比率過高，則分支程度越低，將不利於水溶液的穩定性。於一較佳實施態樣中，本發明之PVA的分支指數(BI) ≦ 0.9；例如但不限於：0.9、0.85、0.8、0.75、0.7、0.65、0.6、0.55、0.5、0.45、0.4、0.35、0.3、0.25、0.2、0.15、0.1、0.05或介於前述任兩個值之間的範圍。於一較佳實施態樣中，本發明之PVA的分支指數(BI)係介於0.7至0.9之間；例如但不限於：0.7、0.71、0.72、0.73、0.74、0.75、0.76、0.77、0.78、0.79、0.80、0.81、0.82、0.83、0.84、0.85、0.86、0.87、0.88、0.89、0.9或介於前述任兩個值之間的範圍。 The "branching index (BI)" described in this paper is used to express the degree of branching of the PVA molecular structure, as shown in Figure 3, which refers to the transfer of the radical chain to the C on the OH group (Figure 3(a) red circle), the resulting non-alkalizable branch (blue circle in Fig. 3(a)). The branching index described herein can be measured using ¹³ C NMR, as shown in Figure 3(b), CH ₂ with chemical shifts in the range of 40 to 50 ppm and CH signals in the range of 65 to 70 ppm can be used for Quantitative branching degree, that is, BI =

, the ratio is too high, the lower the degree of branching, it will be detrimental to the stability of the aqueous solution. In a preferred embodiment, the branching index (BI) of the PVA of the present invention is less than or equal to 0.9; for example, but not limited to: 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35 , 0.3, 0.25, 0.2, 0.15, 0.1, 0.05, or a range between any two of the foregoing. In a preferred embodiment, the branching index (BI) of the PVA of the present invention is between 0.7 and 0.9; for example but not limited to: 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78 , 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, or a range between any two of the foregoing.

The polyvinyl alcohol of the present invention has an excellent transparency. In a preferred embodiment, the transparency (%) of the polyvinyl alcohol of the present invention in a 4% aqueous solution is greater than 98%, such as but not limited to: 98.1%, 98.2%, 98.3%, 98.4%, 98.5%, 98.6% , 98.7%, 98.8%, 98.9%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or 100%.

In a preferred embodiment, the polyvinyl alcohol of the present invention has a number average molecular weight (Mn) < 12815, which is obtained by GPC analysis of the aqueous phase. In a preferred embodiment, the Mn of the polyvinyl alcohol of the present invention is ≤ 12800. In a more preferred embodiment, the Mn of the polyvinyl alcohol of the present invention is between 12600 and 12850, such as but not limited to: 12700, 12710, 12720, 12730, 12740, 12750, 12760, 12770, 12780, 12790, 12800, 12810, 12820, 12830, 12840, 12849, or a range between any of the preceding values.

In a preferred embodiment, the crystallization temperature (Tc) of the polyvinyl alcohol of the present invention ranges from 135 to 138°C, such as but not limited to: 135°C, 135.1°C, 135.2°C, 135.3°C, 135.4°C, 135.5°C 、135.6℃、135.7℃、135.8℃、135.9℃、136℃、136.1℃、136.2℃、136.3℃、136.4℃、136.5℃、136.6℃、136.7℃、136.8℃、136.9℃、137℃、137.1℃ °C, 137.3°C, 137.4°C, 137.5°C, 137.6°C, 137.7°C, 137.8°C, 137.9°C, 138°C, or a range between any two of the foregoing.

The polyvinyl acetate emulsion of the present invention has good viscosity stability, for example, after being placed at 60°C for 2 months, and then measured at normal temperature (25°C), there is basically no delamination or the viscosity change value does not exceed 20,000 (cp); the aforementioned viscosity change values such as but not limited to: not more than 20,000 (cp), not more than 19,000 (cp), not more than 18,000 (cp), not more than 17,000 (cp), not more than 16,000 (cp), not more than 16,000 (cp) over 15,000 (cp), up to 14,000 (cp), up to 13,000 (cp), up to 12,000 (cp), up to 11,000 (cp), up to 10,000 (cp), up to 9,000 (cp), up to 8,000 (cp), up to 7,000 (cp), up to 6,000 (cp), up to 5,000 (cp), up to 4,000 (cp), up to 3,000 (cp), up to 2,000 (cp), up to 1,000 (cp). Example

The following non-limiting examples of aspects of the invention are provided primarily to illustrate the aspects of the invention and the benefits achieved.

According to the present invention, PVA is prepared by controlling alkalinity, block degree and branching degree, and it is formulated into PVA aqueous solutions Examples 1 to 6 and Comparative Examples 1 to 5,

A. Characteristic Analysis

DLS analysis: The device uses a nanoparticle size and potential analyzer (Zetasizer Nano ZS); the scattering angle is 173∘; the PVA RI is 1.479; the PVA absorbance coefficient is 0; the solvent viscosity (water) is 0.8872 cp; ) was 1.33; the temperature was 25 °C; the equilibration time was 0 seconds; the analysis tank used a disposable spectroscopic liquid tank (cuvettes, DTS0012); the number of runs was 11; the running time was 10 seconds; the number of measurements was 3; the measurement The delay between is 0 seconds. The experimental data is the average of three sets of measurements.

6.4 wt% PVA aqueous solution preparation: prepare 6.4 wt% PVA/deionized aqueous solution at 70 °C, stir for 12 to 15 hours, and perform DLS analysis immediately after preparation without additional filter membrane filtration.

Crystallization temperature measurement: The equipment uses a DSC 25 differential scanning calorimeter (DSC) from TA Instruments; the experimental temperature range is 30°C to 250°C, and the temperature is maintained at 30°C and 250°C for 1 minute each. ; The rate of temperature rise and fall was 10℃/min.; The crystallization temperature (Tc) was recorded at 1 ^st cooling.

Block index measurement: the experimental temperature was 27 °C; 80 mg of PVA was dissolved in 1 mL of D ₂ O to prepare a sample; the magnetic field frequency was 500 MHz.

Branch index measurement: the experimental temperature was 27 °C; 15 mg of PVA was dissolved in 1 mL of DMSO to prepare a sample; the magnetic field frequency was 500 MHz.

Transparency measurement of 4 % aqueous solution: the experimental temperature is room temperature; the sample holder: quartz cell, the optical path is 20 mm; the transparency is measured at 430 nm with a spectrophotometer.

Viscosity Determination: Viscosity was measured at various shear rates using a Brookfield LVT viscometer with #4 shaft at 6 rpm/30 degrees/1 atm, followed by measurements of increased shear at less than 1 minute intervals Measurement.

B. Preparation of Emulsion

In a 2L reaction kettle, add 360 g of deionized water, keep the temperature below 30 °C, turn on the mixer, and pour 52 g of PVA into it. After stirring for 15 minutes, raise the temperature to 80 °C and continue stirring until the PVA is completely dissolved. . After the PVA was dissolved, 0.5 g of sodium bicarbonate and 0.5 g of ammonium sulfate were added until completely dissolved. Keep the temperature at 80 degrees, dissolve 0.48g of Ammonium Sulfate in 23g of water, and add it into the reaction kettle at one time. Then, 495 g of vinyl acetate was dropped into the reaction kettle for reaction within 6 hours. After the above reaction time was over, 0.24 g of Ammonium Sulfate was dissolved in 11 g of water, then added to the reaction kettle, and the reaction temperature was raised to 85 degrees, and the reaction was continued for 90 minutes. After the completion of the reaction, cooling was performed to obtain a PVAc emulsion.

C. Results

The dynamic light scattering patterns of Exemplary Examples 1 to 4 and Comparative Examples 1 and 2 according to the present invention are shown in FIG. 4 . The characteristics and experimental conditions of Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1, wherein the ratio (B)=g ⁽²⁾ -1(100)/g ⁽²⁾ -1(0.5); stability In the column: O means homogeneous; x means stratified.

Table 1 Experimental conditions characteristic Alkalized solid content (%) Alkalization temperature (℃) Polymerization conversion rate (%) 4 % aqueous solution transparency (%) 4 % aqueous solution viscosity (cp) Mn Mw Tc (°C) BI n Alkalinity (mole%) Ratio (B) 46.5 42.5 89.88 99.1 5.42 12700 26900 136.5 0.88 0.47 87.86 0.254 1 Example 46.4 42.4 88.59 99.2 5.43 12735 27010 135.8 0.9 0.46 87.58 0.189 2 46.3 42.1 88.9 99.1 5.57 12750 27100 137.1 0.89 0.43 87.81 0.231 3 46.3 41.9 90.12 98.7 5.52 12691 26935 135.5 0.77 0.43 87.17 0.225 4 46.2 42 90.21 99.3 5.44 12750 27110 137.5 0.75 0.42 87.09 0.11 5 46 41.9 88.65 98.1 5.76 12800 27150 137.5 0.9 0.41 87.88 0.298 6 45.4 39.5 86.35 98.0 5.58 12850 27110 140.2 0.98 0.39 87.26 0.38 1 Comparative example 45.1 39.7 86.97 97.8 5.58 12850 27150 139.4 0.93 0.4 87.03 0.38 2 45.7 39.2 86.5 97.5 5.48 12840 27120 140.9 0.96 0.38 87.82 0.431 3 45.3 39.6 86.3 97.6 5.35 12815 27115 140.3 0.94 0.39 87.43 0.431 4 45.1 42.2 80.1 97.9 9.36 25010 58120 137.1 0.9 0.42 87.28 0.38 5

Table 1 - Continued PVAc properties stability PVAc emulsion viscosity (cp) after 2 months at 60°C PVAc solid content (wt%) PVAc emulsion viscosity (cp) O 78,520 59.15 69,700 1 Example O 75,350 59.22 64,500 2 O 64,380 59.18 59,000 3 O 91,000 59.25 78,000 4 O 68,900 59.18 54,200 5 O 58,200 59.22 48,000 6 X Layered 59.19 21,100 1 Comparative example X Layered 59.19 18,890 2 X Layered 59.24 20,010 3 X Layered 59.08 30,320 4 X Layered 59.22 23,800 5

Examples 1 to 6 show that, with g ⁽²⁾ -1 ratios at specific decay times, specific block lengths and degree of branching, block length and degree of branching were found to correlate with whether PVA produces larger particle aggregation in aqueous solutions , the aggregation will further affect the emulsion stability and protective colloid properties, so the present invention can obtain PVA with high protective colloid properties by controlling the PVA polymerization and alkalizing conditions.

In contrast, the comparative example is more likely to form intermolecular aggregation in the aqueous state, resulting in a lower g ⁽²⁾ -1(τ) decay rate, and correspondingly, the emulsion viscosity is relatively unstable. When the η block degree is less than 0.4, the higher the block property (more block), the longer the crystalline segment, and the lower the aqueous solution stability. When the branching index is greater than 0.9, the lower the degree of branching, the lower the stability of the aqueous solution.

To sum up, the PVA of the present invention achieves appropriate viscosity stability through appropriate alkalization conditions, appropriate block length and branching degree, and the PVA aqueous solution as a protective colloid can have better protective colloid effect, and It can reduce the amount of polyvinyl alcohol used, and has the advantages of relatively stable emulsion viscosity.

All ranges provided herein are intended to include each specific range within the given range and combinations of subranges between the given ranges. Furthermore, unless otherwise indicated, all ranges provided herein are inclusive of the endpoints of the range, eg, between 1-5 and both inclusive. Thus, the range 1-5 specifically includes 1, 2, 3, 4, and 5, as well as subranges such as 2-5, 3-5, 2-3, 2-4, 1-4, and the like.

All publications and patent applications cited in this specification are incorporated herein by reference, and each individual publication or patent application is expressly and individually indicated to be incorporated by reference for any and all purposes. In the event of inconsistency between this document and any publication or patent application incorporated herein by reference, this document controls.

none.

Implementations of the present techniques will now be described, by way of example only, with reference to the accompanying drawings, in which:

1 is a schematic diagram illustrating the dynamic light scattering: (a) is a schematic diagram of the dynamic light scattering measurement state; (b) is a schematic diagram of the particle size distribution of large particles and small particles.

Figure 2 is an autocorrelation function map of dynamic light scattering.

Figure 3 is an illustration of the degree of branching of an exemplary PVA of the present invention: (a) a schematic diagram of radical chain transfer resulting in branching; (b) a carbon 13 nuclear magnetic resonance spectrum.

4 shows the dynamic light scattering spectra of the exemplary embodiments 1 to 4 and comparative examples 1 and 2 according to the present invention. When τ is 100 μs, the y-axis of the examples is all less than 0.2, and the comparative examples are all greater than 0.2.

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none.

Claims (10)

A kind of polyvinyl alcohol, it is characterized in that, this polyvinyl alcohol has a ratio (B), this ratio (B)=g ⁽²⁾ -1(τ=100 μs)/g ⁽²⁾ -1(τ=0.5 μs ), which was obtained by measuring a 6.4 wt% polyvinyl alcohol solution by dynamic light scattering (DLS), wherein the ratio (B) was in the range of 0 < (B) < 0.38. The polyvinyl alcohol according to claim 1, wherein the polyvinyl alcohol further has a block index (η), and the block index (η) is in the range of 0.4 < η < 1. The polyvinyl alcohol as described in claim 1, wherein the polyvinyl alcohol further has a 4% aqueous solution transparency (%), and the 4% aqueous solution transparency (%) is greater than 98%. The polyvinyl alcohol of claim 1, wherein the polyvinyl alcohol further has a branching index (BI), and the branching index (BI) ≦ 0.9. The polyvinyl alcohol according to item 1 of the claimed scope, wherein the polyvinyl alcohol further has a number average molecular weight (Mn), and the number average molecular weight (Mn) ≦ 12800. The polyvinyl alcohol as described in claim 5, wherein the polyvinyl alcohol further has a degree of hydrolysis, and the degree of hydrolysis is in the range of 86 to 89 mole%. The polyvinyl alcohol as described in claim 1, wherein the polyvinyl alcohol further has a crystallization temperature (Tc), and the crystallization temperature (Tc) ranges from 135°C to 138°C. A protective solution is characterized in that, it comprises the polyvinyl alcohol as described in any one of the first to seventh patent application scope as a dispersant. A polyvinyl acetate emulsion, characterized in that, the polyvinyl acetate emulsion is synthesized through the protection solution as described in item 8 of the patent application scope. The polyvinyl acetate emulsion as described in item 9 of the claimed scope, wherein the polyvinyl acetate emulsion basically does not produce delamination or the viscosity change value does not exceed 20,000 (cp) after being placed at 60° C. for 2 months.

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