CN113045696B

CN113045696B - Zero-additive low-odor polymer latex and preparation method thereof

Info

Publication number: CN113045696B
Application number: CN201911362090.8A
Authority: CN
Inventors: 贾贵玉; 马吉全; 韩强; 张伟辉; 麻宁; 纪学顺; 景传明
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2019-12-26
Filing date: 2019-12-26
Publication date: 2022-09-20
Anticipated expiration: 2039-12-26
Also published as: CN113045696A

Abstract

The invention provides a preparation method of a zero-additive low-odor polymer latex containing an ethyl acrylate monomer, which comprises a small amount of acetoacetate or acetoacetic acid amide functional group serving as a monomer or a non-polymeric additive, and a long EO number nonionic emulsifier is used in a matching manner.

Description

Zero-additive low-odor polymer latex and preparation method thereof

Technical Field

The invention belongs to the field of polymer chemistry, and particularly relates to a zero-additive low-odor polymer latex and a preparation method thereof.

Background

With the increasing requirements of people on health and environmental protection, the VOC content of the emulsion paint is more and more concerned by people, and the development of the emulsion paint with zero additive and low odor has good market prospect. The VOC substances in the latex paint have different chemical properties, and the sources of the VOC substances comprise residual monomers in raw material emulsion for preparing the latex paint, impurities in the monomers, VOC generated in the preparation process, and added film-forming auxiliary agents and antifreeze agents, so that the reduction of the content of the VOC substances is the key for reducing the VOC in the latex paint.

European patent EP1553106 discloses a low odor polymer dispersion containing styrene monomer which reduces the level of benzaldehyde in the dispersion primarily by using a deodorant comprising an amino alcohol, hydroxylamine and hydrazine, which has the advantage of significantly reducing the level of impurity benzaldehyde in the monomer, but the VOC generated during emulsion preparation and the added coalescents and anti-freeze agents remain the major contributors to odor.

Chinese patent CN104105728A discloses a polymer latex binder useful in zero or low VOC coating compositions, which mainly realizes excellent film forming property and low temperature stability without adding film forming aid and anti-freezing agent by blending hard phase polymer latex and soft phase polymer latex, but the emulsion has the disadvantages of VOC generated in the preparation process and complexity of the preparation process.

Residual monomers in the emulsion, impurities in the monomers and VOC generated in the preparation process can be eliminated by methods such as selection of raw materials, adjustment of polymerization reaction, steam stripping and the like, and the added film-forming assistant and antifreeze are closely related to the film-forming property and freeze-thaw stability of the emulsion paint prepared from the emulsion, so that the development of the emulsion paint which can enable the prepared emulsion paint to have good film-forming property and freeze-thaw stability on the premise of not adding the film-forming assistant and antifreeze is the difficulty for preparing the zero-added low-odor polymer latex.

In order to solve the difficult problems, the freeze-thaw stability of the polymer latex needs to be improved, and the traditional method for improving the freeze-thaw stability of the polymer latex is to add micromolecular antifreeze such as ethylene glycol, propylene glycol and the like, and the addition of the antifreeze obviously improves the content of VOC in the system. Under the condition of not adding an antifreeze agent, one method for realizing excellent freeze-thaw stability is to improve the glass transition temperature of the polymer and reduce the deformation fusion capacity of the emulsion particles in the freeze-thaw process, but the improvement of the glass transition temperature of the polymer increases the dosage of the film forming auxiliary agent in the film forming process of the emulsion paint; another method for improving the freeze-thaw stability of the polymer latex is to add more hydrophilic monomers and form a thicker hydration layer to wrap the latex particles, but increasing the amount of the hydrophilic monomers can improve the hydrophilicity of a paint film and inevitably can cause the scrubbing resistance and the stain resistance of the paint film to be reduced. In order to reduce the amount of the film-forming assistant, i.e. the paint film can be formed at a lower temperature, the polymer needs to be designed to have a lower glass transition temperature, but the lower glass transition temperature can greatly reduce the scrub resistance and freeze-thaw stability of the paint film, so that great contradictions exist among the low film-forming temperature, the excellent freeze-thaw stability and the high scrub resistance, and therefore, if the contradictions can be solved, zero-addition low-odor polymer latex which enables the prepared latex paint to have good film-forming property and freeze-thaw stability is developed, the development of the latex paint industry must bring great progress to the coating industry.

Disclosure of Invention

In view of the above problems of the prior art, the present invention provides a zero-additive low-odor polymer latex. By selecting specific polymeric monomers, emulsifying agents and other raw materials, the prepared polymer latex has excellent freeze-thaw stability at a lower glass transition temperature, and the prepared latex paint has excellent low-temperature film-forming performance and freeze-thaw stability, excellent scrub resistance and stain resistance and a function of decomposing free formaldehyde and other harmful gases in the air without adding an antifreezing agent and a film-forming aid.

In order to achieve the purpose, the invention adopts the following technical scheme:

a zero-added low odor polymer latex comprising in composition:

40 to 55% by weight of a vinyl copolymer, wherein the starting material for the vinyl copolymer comprises components (a) and (b):

(a) 65-90% ethyl acrylate, and

(b)0.1 to 15wt%, preferably 0.1 to 10% of an ethylenically unsaturated monomer having at least one acetoacetate functional group;

and, the polymer latex further comprises:

(c) 0-3 wt% of polymerizable nonionic emulsifier, preferably, the EO number of the emulsifier is 10-40;

(d)0 to 3wt% of a non-polymeric nonionic emulsifier, preferably the emulsifier EO number is 10 to 40,

wherein the sum of the contents of (c) and (d) is 0.2 to 3% based on the weight of the polymer latex.

The (b) ethylenically unsaturated monomer having at least one acetoacetate functional group is selected from at least one of allyl acetoacetate, acetoacetoxy acrylate, acetoacetoxy methacrylate, 2, 3-bis (acetoacetoxy) propyl methacrylate, preferably acetoacetoxy ethyl methacrylate (AAEM).

In a preferred embodiment, the polymer latex further comprises 0 to 15wt% of a non-polymeric compound (e) containing an acetoacetate or acetoacetamide functional group, and the sum of the contents of the monomer (b) and the compound (e) is 0.1 to 15wt% based on the weight of the vinyl copolymer. In a preferred embodiment, the weight ratio of (e) component to (b) component is from 0 to 0.4:1, preferably from 0.1 to 0.3: 1.

The non-polymeric compound containing the acetoacetate or the acetoacetamide functional group (e) is at least one selected from ethyl acetoacetate, acetoacetamide, N-acetoacetanilide, N- (acetoacetyl) sulfanilic acid potassium, diacetyl acetyl-2, 5-dimethyl p-phenylenediamine, diacetyl acetyl p-phenylenediamine and 2-methoxyethyl acetoacetate.

The non-polymeric compound (e) containing an acetoacetate or acetoacetamide functionality can act as an additive to synergistically act with the aldehyde removal of component (b).

The polymerizable nonionic emulsifier (c) is at least one of allyl polyoxyethylene ether, allyl nonylphenol polyoxyethylene ether, allyloxy polyoxyethylene ether, acrylamide polyoxyethylene ether, styrene polyoxyethylene ether, (meth) acrylic polyoxyethylene ether and maleate polyoxyethylene ether, and preferably allyl nonylphenol polyoxyethylene ether and/or styrene polyoxyethylene ether.

The non-polymeric nonionic emulsifier (d) is polyoxyethylene carboxylate, polyoxyethylene polyol carboxylate, C ₉ -C ₁₆ At least one of fatty alcohol-polyoxyethylene ether and aralkyl polyoxyethylene ether with 1-3 benzene rings, preferably C ₉ -C ₁₆ Fatty alcohol polyAt least one of an oxyethylene ether and an aralkyl polyoxyethylene ether having 1 to 3 benzene rings.

The sum of (c) and (d) is in the range of 0.2 to 3%, and in a preferred embodiment the effective mass ratio of the (c) and (d) components is 0.02-0.4:1, preferably 0.1-0.4: 1.

The zero-additive low-odor polymer latex is prepared from the raw materials including the components (a) to (e) and also comprises hard monomers, hydrophilic monomers and the like which are commonly used in the field.

The hard monomer comprises one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate and cyclohexyl methacrylate. The amount is 5 to 30% by weight, preferably 8 to 25% by weight, based on the weight of the vinyl copolymer.

The hydrophilic monomer is one or more of acrylic acid, methacrylic acid, itaconic acid, acrylamide, hydroxymethyl acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate, and the dosage of the hydrophilic monomer is 0.2-2.5%, preferably 0.5-2% of the weight of the vinyl copolymer.

The polymer latex with no addition and low odor also comprises an anionic emulsifier, an initiator, a pH regulator and a post-treatment agent, wherein the post-treatment agent comprises an oxidant and a reducing agent.

The initiator is one or more of sodium persulfate, potassium persulfate and ammonium persulfate. The amount is 0.1 to 0.8%, preferably 0.2 to 0.6% by weight of the vinyl copolymer.

The anionic emulsifier is selected from non-polymeric and polymerizable anionic emulsifiers, wherein the non-polymeric anionic emulsifier is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfonate, alcohol ether sulfosuccinate, alkyl alcohol ether sulfate and alkyl alcohol ether phosphate, and the polymerizable anionic emulsifier is one or more of sodium p-styrene sulfonate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and sodium vinyl sulfonate. The effective weight ratio of nonionic emulsifier (sum of c and d) to anionic emulsifier is from 0.5 to 6:1, preferably from 1.5 to 2.5: 1.

In a preferred embodiment, the anionic emulsifier comprises both non-polymeric and polymerizable anionic emulsifiers, wherein the effective weight ratio of non-polymeric anionic emulsifier to polymerizable anionic emulsifier is from 1 to 8:1, preferably from 2 to 6: 1.

In a more preferred embodiment, the emulsifier for preparing the polymer latex is composed of a non-polymeric nonionic emulsifier, a polymerizable nonionic emulsifier, a non-polymeric anionic emulsifier, and a polymerizable anionic emulsifier. The nonionic emulsifier with a special structure is adopted, so that the polymer latex has excellent electrolyte stability on one hand, and can be adsorbed on the surface of latex particles on the other hand, and the polymer has excellent freeze-thaw stability at a lower glass transition temperature; the non-polymeric anionic emulsifier is adopted, so that the surface of the emulsion particle is provided with a layer of negative charges, and the mechanical stability of the emulsion and the stability in the polymerization process can be effectively improved; by introducing the polymerizable anionic emulsifier, the polymerization stability is improved, and meanwhile, the migration from the interior of a paint film to the surface is avoided in the film forming process of the paint film, so that the water resistance and the gloss of the paint film can be effectively improved. When the four emulsifiers are mixed and used in the proportion, the prepared polymer latex can have more excellent freeze-thaw stability, mechanical stability and scrub resistance at a lower glass transition temperature, and the prepared latex paint has more excellent water resistance after being formed into a film.

The pH regulator is one or more of sodium hydroxide, potassium hydroxide, ammonia water, triethylamine, ethanolamine, dimethylethanolamine, diethanolamine and triethanolamine.

The oxidant is one or more of tert-butyl hydroperoxide, hydrogen peroxide, sodium persulfate, potassium persulfate and ammonium persulfate. The reducing agent is one or more of sodium bisulfite, sodium metabisulfite and vitamin C. The amount of the oxidizing agent and the reducing agent is 0.1 to 0.4% by weight, respectively, of the copolymer.

In the present invention, the raw material of the vinyl copolymer includes components (a), (b), a hard monomer, and a hydrophilic monomer.

The invention also relates to a preparation method of the zero-addition low-odor polymer latex, which adopts one of homogeneous emulsion polymerization or core-shell emulsion polymerization.

In a particular embodiment, the method comprises the following steps:

1) adding 90-98wt% of non-polymeric anionic emulsifier, all polymerizable nonionic emulsifier, 25-35% of deionized water, all ethyl acrylate, all acetoacetic ester functional group-containing ethylenically unsaturated monomers, all hard monomers and hydrophilic monomers into a pre-emulsifying kettle, and fully stirring for 10-20 minutes to prepare pre-emulsion;

2) adding 30-50% of initiator in the total amount of the initiator into deionized water in the total amount of 1-6% of deionized water to dissolve to obtain a dropwise added initiator;

3) adding the rest initiator into deionized water accounting for 1-6% of the total amount of the deionized water to dissolve to obtain a kettle bottom initiator solution;

4) adding the rest of the non-polymeric anionic emulsifier and the rest of the deionized water into a reaction kettle, fully stirring and dissolving, heating to 80-90 ℃, adding 1-8% of the pre-emulsion obtained in the step 1) into the reaction kettle, adding the initiator solution obtained in the step 3) into the reaction kettle after uniformly stirring, and reacting for 10-20 minutes to obtain a seed emulsion;

5) after the reaction in the step 4) is finished, controlling the reaction temperature to be 80-90 ℃, simultaneously dripping the residual pre-emulsion prepared in the step 1) and the dripping initiator in the step 2), wherein the dripping time is 3-4 h, and after the dripping is finished, keeping the temperature for 20-60 min;

6) and cooling the reaction kettle to 70-80 ℃, adding a pH regulator, and regulating the pH of the system to 7-9. Dropwise adding the post-treatment agent into the reaction kettle for 20-60 min, and preserving heat for 30-60 min after dropwise adding;

7) cooling to below 45 deg.C, adding non-polymeric nonionic emulsifier and non-polymeric compound containing acetoacetate or acetoacetic acid amine functional group;

8) optionally, the polymer latex is subjected to a stripping treatment, the discharge being filtered after the stripping has been completed.

In the present invention, the stripping treatment is a conventional process condition which may be the present invention, for example, preferably, the stripping treatment is performed under the following conditions: the polymer latex is stripped in a single stage, continuous stripping line with relative flow rates of air, steam and dispersion of 1:0.2 to 1:8 to 12.

Preferably, the stripping is such that the level of tert-butanol produced in the polymer latex is less than 25 ppm.

The polymer latex of the invention is not added with film forming auxiliary agent and antifreeze agent in the preparation process.

The polymer latices of the invention can be used for the preparation of latex paints.

The invention has the beneficial effects that:

1. the zero-addition low-odor polymer latex adopts a thermal initiation and oxygen-reduction initiation composite initiation system, so that the polymer latex does not contain or contains a very small amount of residual monomers after the polymerization is finished.

2. The zero-additive low-odor polymer latex adopts a stripping technology to remove micromolecule organic matters, particularly odorous micromolecule organic matters (such as tertiary butanol) in the polymer latex, so that the content of the micromolecule organic matters is extremely low.

3. The zero-additive low-odor polymer latex adopts polymerizable monomer ethyl acrylate, and a paint film has an excellent film forming effect under the condition of not adding a film forming auxiliary agent through the water absorption self-plasticization effect after the ethyl acrylate is polymerized.

4. The zero-addition low-odor polymer latex adopts the nonionic emulsifier with large EO number, and is adsorbed on the surface of the latex particle to form a steric hindrance effect on one hand, and on the other hand, the nonionic emulsifier combines a large amount of bound water to form a very thick hydration layer on the surface of the latex particle, so that the zero-addition low-odor polymer latex has excellent freeze-thaw stability without adding an antifreeze agent.

5. The synthesis process of the zero-additive low-odor polymer latex is simple, the operation is simple and convenient, the cost is lower, and the safety is high.

Detailed Description

The invention is further illustrated by the following specific examples, which are not to be construed as limiting the invention.

The raw materials used in the examples were as follows:

for short	Chinese chemical name	Purity/%)
			EA	Acrylic acid ethyl ester	＞99.5
BA	Acrylic acid butyl ester	＞99.5
			EHA	Acrylic acid isooctyl ester	＞99.5
MMA	Methacrylic acid methyl ester	＞99.5
			AA	Acrylic acid	＞99.5
AAEM	Acetoacetoxy ethyl methacrylate	＞99.5
			SDS	Sodium dodecyl sulfate	100
COPS-1	3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt	40
			ANPEO 10	Allyloxy nonyl phenol polyoxyethylene ether	100
3307	Isomeric tridecanol polyoxyethylene ether	70
			AAM	Acetoacetamide	97
APS	Ammonium persulfate	100
			MEA	Ethanolamine	100
t-BHP	Tert-butyl hydroperoxide	70
			NaHSO ₃	Sodium bisulfite	100

Calculation of the glass transition temperature of the polymer:

in the formula w ₁ ，w ₂ ，…w _n And T _g1 ，T _g2 …T _gn The mass fraction of each polymerized monomer in the total monomer and the vitrification temperature value are shown.

The following stripping treatment procedure was used:

the sample was preheated to 55 ℃ in a buffer vessel and then stripped once, twice, three times and four times through a single stage, continuous stripping line. The relative flow rates of air, steam and dispersion in the stripping were 1:0.5: 10.

Evaluation of odor: evaluation of odor was performed based on olfactory sensation, and 10 persons were selected to evaluate odor in the polymer latex tank. The evaluation results are graded in five grades of 1-5, and are as follows:

grade	Unpleasant odor
		5	Is free of
4	Light and slight
		3	Medium and high grade
2	High strength
		1	Severe severity of disease

Note: the unpleasant odor is from residual monomers, monomer impurities, film forming aids, anti-freeze agents and odorous substances formed in the reaction process.

Low Temperature Coalescence (LTC) evaluation: putty is applied to a high-density asbestos-free fiberboard A4, the substrate accords with NAF (non-asbestos) in JC/T412.1-2006, after drying, the putty is polished to be flat by sand paper, after a putty board with the size of A4 is subjected to film scraping by a 400-micron film making device, the putty board is immediately placed into a low-temperature box at the temperature of 3 ℃, and the cracking condition of the surface of a coating film is observed for comparison after 4 hours. The degree of cracking was rated on a scale of 1 to 5 as follows:

severe cracking 1 ═

2-medium cracking

Cracking of 3 ═ certain

Mild cracking of 4 ═

No cracking 5 ═

Evaluation of freeze-thaw stability: and (3) putting the paint sample into a 1L plastic container, sealing, putting into a low-temperature box at minus 7 ℃, taking out the container after 18 hours, placing in an environment with the standard temperature of 23 +/-2 and the relative humidity of 50 +/-5% for 6 hours, opening the container, fully stirring to observe whether hard blocks, agglomeration and separation phenomena exist, if so, ending the experiment, and recording the cycle number. If not, repeating the next cycle.

Evaluation of scrub resistance: the scrub resistance of the paint films was tested according to GB/T9266-2009.

Evaluation of polymerization stability: taking 1kg of polymer latex, filtering the polymer latex by using a 100-mesh filter screen and a 325-mesh filter screen in sequence, placing the filtered substance in an oven at 150 ℃, taking out and weighing the filtered substance after 20 minutes, wherein the heavier the filtered substance is, the higher the slag content is. When the 100 mesh slag contains less than 150ppm and the 325 mesh slag contains less than 200ppm, the polymerization stability is passed.

Evaluation of formaldehyde purification efficiency and durability: and testing the purification efficiency and the durability of the purification effect of the formaldehyde according to the standard JC/T1074-2008.

Example 1:

preparation of Polymer latex containing Ethyl Acrylate (EA)

A zero-addition polymer latex A is prepared by the following process:

1) 10g of sodium lauryl sulfate, 5g of COPS-1, 280g of deionized water, 145g of MMA, 800g of EA, 50g of AAEM and 5g of AA were mixed to obtain a pre-emulsion (ME).

2) 1.6g of APS and 40g of water were mixed to give a dropwise addition initiator solution.

3) 2.4g of APS and 24g of water were mixed to give a bottom initiator solution.

4) Adding 0.5g of sodium dodecyl sulfate and 500g of deionized water into a reaction kettle, fully stirring and dissolving, heating to 85 ℃ in a nitrogen environment, when the temperature in the reaction kettle is raised to 85 ℃, sequentially adding 50g of pre-emulsion (ME) and all kettle bottom initiator solutions, and keeping the temperature for 10 min.

5) Controlling the temperature to be 85 ℃, simultaneously dropwise adding the rest pre-emulsion (ME) and all the initiator solution, and preserving the temperature for 20min after the dropwise adding is finished for 3 h.

6) The temperature was reduced to 75 ℃ and MEA was added to neutralize the system to pH 8. 3g of t-BHP (70%) solution and 2g of NaHSO were added dropwise to the reactor over 30min ₃ (dissolved in 40g of deionized water) and incubated for a further 30 min.

7) Cooling to below 45 deg.C, adding 28.6g non-polymeric nonionic emulsifier 3307, filtering and discharging.

Comparative examples 1 to 2:

comparative examples 1-2 the same procedure as in example 1 was followed except that the amount and kind of raw materials were changed as shown in the following Table 1, wherein comparative examples 1 and 2 gave polymer latices B and C, respectively.

Table 1: comparative examples 1 to 2 raw Material amount (g) and kind

Example 2:

preparation of polymer latex containing polymerizable nonionic emulsifier ANPEO 10:

according to the procedure of example 1, a polymer latex D containing polymeric nonionic emulsifier ANPEO 10 was prepared, except that: the pre-emulsion (ME) was prepared by mixing 10g sodium dodecyl sulfate, 5g COPS-1, 20g ANPEO 10, 280g deionized water, 145g MMA, 800g EA, 50g AAEM, and 5g AA. In addition, when the temperature of the polymer latex in the step 7) is reduced to below 45 ℃, the non-polymeric nonionic emulsifier 3307 is not added.

Example 3:

preparation of COPS-1 Polymer latex without polymerizable anionic emulsifier:

COPS-1 Polymer latex E, which did not contain a polymerizable anionic emulsifier, was prepared according to the procedure of example 1 and Table 2.

Example 4:

preparation of a polymer latex containing four emulsifiers:

a polymer latex F containing two nonionic emulsifiers was prepared according to the procedure of example 1 and Table 2.

The amounts and types of the raw materials of examples 1 to 4 are shown in Table 2.

Table 2: EXAMPLES 1-4 amounts (g) and kinds of raw materials

Example 5:

preparation of a polymer latex of non-polymeric and polymerizable compounds containing acetoacetate or acetoacetate functionality:

a polymer latex G containing AAM and AAEM was prepared according to the procedure of example 4. Wherein AAM is added when the polymer latex of step 7) is cooled to below 45 ℃. The amounts and types of the raw materials of example 5 are shown in Table 3.

Table 3: EXAMPLE 5 amount (g) and kind of raw Material

The polymer latex samples A-G were evaluated for performance and the results are shown in Table 4:

TABLE 4

Latex A

Latex B

Latex C

Latex D

Latex E

Latex F

Latex G

Stability of polymerization

By passing

Failed through

By passing

Odor grade

3

-

3

Additional performance evaluations were performed on samples A-G according to the coating formulations shown in Table 5, with the results shown in Table 5:

table 5: coating Performance evaluation formulations and results prepared with Polymer latex samples A-G

From the test results of the latexes a, B, C, it is clear that excellent low temperature coalescence can be achieved with EA in case the polymers have the same Tg, while other esters do not achieve low temperature thick coating film, so EA has excellent low temperature film forming properties compared to EHA.

Example 6: stripping of the Polymer latex F

Sample H: sample F was subjected to a single stripping.

Sample I: sample F was twice stripped.

Sample J: sample F was stripped three times.

Sample K: sample F was stripped four times.

The tertiary butanol content and odor evaluation results of sample F, H, I, J, K are shown in Table 5.

Table 5:

sample (I)	tert-Butanol content/ppm	Olfactory sensation	Grade
				F	128	Medium and high grade	3
H	86	Medium grade	3
				I	54	Medium and high grade	3
J	35	Medium and high grade	3
				K	22	Light and slight	4

The resulting latex was used to make coatings according to the formulation shown in table 6 below:

the paint formulation was prepared using the sample a latex of example 1:

table 6:

evaluation formula	Amount of material (g)
		Water (W)	200
Hydroxyethyl cellulose ether	4
		NaOH aqueous solution (10%)	1
Wetting agent BD-109	2
		Dispersant SN-5040	5
Antifoam NXZ	2
		Titanium white powder	200
Ground calcium carbonate	50
		Kaolin clay	150
Diatomite	20
		Bactericide BIT	2
Freeze-thaw resistance agent FT100	5
		Polyurethane thickener U300	8
Water (W)	21
		Latex A	330
In total (g)	1000

The paint is detected, the performance of the paint meets the requirements of the national standard GB/T34676-:

table 7:

Claims

1. a zero-additive low-odor polymer latex, characterized in that the composition thereof comprises:

40-55% by weight of a vinyl copolymer;

wherein the raw material of the vinyl copolymer comprises components (a) and (b):

(a) 65-90% of ethyl acrylate,

(b)0.1 to 15wt% of an ethylenically unsaturated monomer having at least one acetoacetate functional group;

and, the polymer latex further comprises:

(c) 0-3 wt% of polymerizable nonionic emulsifier, wherein the EO number of the emulsifier is 10-40;

(d) 0-3 wt% of non-polymeric nonionic emulsifier, wherein the EO number of the emulsifier is 10-40;

wherein the sum of the amounts of (c) and (d) is 0.2 to 3%, the amounts of (c) and (d) being based on the weight of the polymer latex;

the polymer latex also comprises an anionic emulsifier, and the effective weight ratio of the nonionic emulsifier to the anionic emulsifier is 1.5-2.5: 1; the anionic emulsifier is selected from non-polymeric and polymerizable anionic emulsifiers, wherein the non-polymeric anionic emulsifier is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfonate, alcohol ether sulfosuccinate, alkyl alcohol ether sulfate and alkyl alcohol ether phosphate, and the polymerizable anionic emulsifier is one or more of sodium p-styrene sulfonate, 3-allyloxy-2-hydroxy-1-propanesulfonate sodium salt and sodium vinyl sulfonate;

the polymer latex is not added with an antifreezing agent and a film-forming auxiliary agent; the polymer latex adopts a composite initiation system of thermal initiation and oxidation-reduction initiation.

2. The polymer latex of claim 1, wherein the effective mass ratio of components (c) and (d) is from 0.02 to 0.4: 1.

3. The polymer latex of claim 1, wherein the effective mass ratio of (c) to (d) components is 0.1 to 0.4: 1.

4. The polymer latex according to claim 1, wherein the content of (b) in the raw material of the vinyl copolymer is 0.1 to 10%.

5. The polymer latex of claim 1, wherein the ethylenically unsaturated monomer having at least one acetoacetate functional group of component (b) is selected from at least one of allyl acetoacetate, acetoacetoxy acrylate, acetoacetoxy methacrylate, 2, 3-bis (acetoacetoxy) propyl methacrylate.

6. The polymer latex of claim 1, wherein component (b) is acetoacetoxy ethyl methacrylate.

7. The polymer latex according to any of claims 1 to 6, wherein the polymer latex starting material further comprises a non-polymeric compound (e) containing an acetoacetate or acetoacetamide functional group, and the sum of the amounts of monomer (b) and compound (e) is in the range of from 0.1 to 15wt%, based on the weight of the vinyl copolymer; (e) the weight ratio of the component (a) to the component (b) is 0-0.4: 1.

8. The polymer latex of claim 7, wherein the weight ratio of (e) component to (b) component is from 0.1 to 0.3: 1.

9. The polymer latex of claim 7, wherein (e) the non-polymeric compound having an acetoacetate or acetoacetamide functionality is selected from at least one of ethyl acetoacetate, acetoacetamide, acetoacetanilide, potassium N- (acetoacetyl) sulfa-mate, diacetyl-2, 5-dimethyl-p-phenylenediamine, diacetyl-p-phenylenediamine, and 2-methoxyethyl acetoacetate.

10. The polymer latex according to any of claims 1 to 6, wherein the starting material of the vinyl copolymer further comprises a hard monomer in an amount of 5 to 30% by weight based on the weight of the vinyl copolymer and a hydrophilic monomer in an amount of 0.2 to 2.5% by weight based on the weight of the vinyl copolymer.

11. The polymer latex of claim 10, wherein the hard monomer is present in an amount of 8 to 25% by weight of the vinyl copolymer and the hydrophilic monomer is present in an amount of 0.5 to 2% by weight of the vinyl copolymer.

12. The polymer latex of claim 10, wherein the hard monomer comprises one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate; the hydrophilic monomer is one or more of acrylic acid, methacrylic acid, itaconic acid, acrylamide, hydroxymethyl acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.

13. The polymer latex according to any one of claims 1 to 6, wherein said (c) polymerizable nonionic emulsifier is at least one member selected from the group consisting of allyl polyoxyethylene ether, allyl nonylphenol polyoxyethylene ether, allyloxy polyoxyethylene ether, acrylamide polyoxyethylene ether, styrene polyoxyethylene ether, (meth) acrylic polyoxyethylene ether, and maleate polyoxyethylene ether.

14. The polymer latex of claim 13, wherein (c) is selected from the group consisting of allylnonylphenol polyoxyethylene ether and/or styrene polyoxyethylene ether.

15. The polymer latex according to any one of claims 1 to 6 and 14, wherein said non-polymeric nonionic emulsifier (d) is polyoxyethylene carboxylate, polyoxyethylene polyol carboxylate, C ₉ -C ₁₆ At least one of fatty alcohol-polyoxyethylene ether and aralkyl polyoxyethylene ether with 1-3 benzene rings.

16. The polymer latex of claim 15, wherein (d) is selected from C ₉ -C ₁₆ At least one of fatty alcohol-polyoxyethylene ether and aralkyl polyoxyethylene ether with 1-3 benzene rings.

17. The polymer latex according to any of claims 1 to 6, wherein the effective weight ratio of non-polymeric anionic emulsifier to polymerizable anionic emulsifier in the anionic emulsifier is 1-8: 1.

18. The polymer latex of claim 17, wherein the effective weight ratio of non-polymeric anionic emulsifier to polymerizable anionic emulsifier in the anionic emulsifiers is from 2 to 6: 1.

19. A process for preparing the polymer latex of any one of claims 1 to 18, comprising:

1) adding 90-98wt% of non-polymeric anionic emulsifier, all polymerizable nonionic emulsifier, 25-35% of deionized water, all ethyl acrylate, all acetoacetic ester functional group-containing ethylenically unsaturated monomers, all hard monomers and hydrophilic monomers into a pre-emulsifying kettle, and fully stirring to prepare a pre-emulsion;

5) after the reaction in the step 4) is finished, controlling the reaction temperature to be 80-90 ℃, adding the residual pre-emulsion prepared in the step 1) and the dropwise adding initiator in the step 2) within 3-4 h, and keeping the temperature for 20-60 min;

6) cooling the reaction kettle to 70-80 ℃, adding a pH regulator, regulating the pH of the system to 7-9, adding a post-treatment agent into the reaction kettle within 20-60 min, and keeping the temperature for 30-60 min;

7) cooling to below 45 deg.C, adding non-polymeric nonionic emulsifier and non-polymeric compound containing acetoacetate or acetoacetamide functional group;